text:
An implementation of Vincent Thiernesse's Efficient Power Supply

In Linear Audio Vol 12, Vincent Thiernesse proposed Efficient, unity power-factor, low cost audio power amp supplies. The article discussed the concepts and a general imnplementation. Vincent also wrote about this in the AudioXpress June 2016 issue: You can diy an ecological power supply for power amplifiers. That article describes a practical implementation. The folks at AudioXpress kindly placed it online; it nicely complements the L|A article. Recommended reading.

Building notes for Hannes Almaier High Octane phono preamp (Vol 6)

Hannes collected some practical building notes for his High octane preamp, including a parts list.

You can download the PDF here.

Thermal transient variation of power amp quiescent current

For a limited time I offer my Vol 9 article Thermal transient variation of power amp quiescent current - Instrumentation and findings for free download. Enjoy!

Appendices for Burkhard Vogel's Challenging BJT noise in Vol 13

Mr. Vogel provided several appendices for his article that did not make it into the printed Volume 13. They are downloadable here; with thanks to author Vogel.

M-files for the electro-acoustic test system by VanderKooy and Mann in Vol 13

The article in Vol 13 describes the hardware and software setup for an electro-acoustic measurement system based on a soundcard driven by a MathLab / Octave compatible collection of test routines. You can develop your own test routines for your own specific test needs, but the authors have kindly provided a set of test scripts to get you going. Each set of scripts also has a readme file to explain the flow and use.

M-files & readme for part1     M-files & readme for part 2

Design data package for Marcel van de Gevel's Valve DAC from Vol 13

Although Marcel's article in Vol 13 is very complete, some of the more practical desing information like FPGA code and PCB layouts didn't make it into the printed version. Marcel has graciously agreed to make the complete Tube Dac data package available here. This has everything needed for adventurous builders to replicate this design.

Update January 16, 2018: updated version 2.1 from previous version 2: following discussions at, Marcel made some changes to his tube DAC. The zip file contains version 2.1 of the Verilog code and user constraints file for the valve DAC, as well as an MCS file that can be directly programmed into the flash memory of the FPGA module. Use the MCS file if you want to use the code as-is, the Verilog and UCF files are only needed for those who want to change the code themselves.
Compared to version 1, version 2.1 adds an I2S input on the extension connector. This input (which supports 2.8224 MHz DSD64 over DoP) can also be switched to a raw DSD mode, in which it supports 2.8224 MHz DSD64 and 5.6448 MHz DSD128. For PCM, the extra I2S input supports sample rates from 12.5 kHz up to 216 kHz and word lengths from 8 up to and including 32 bits. The I2S input can only operate in slave mode.
Compared to version 2, version 2.1 fixes a bug that could bring the DSD FIR filters into an undefined state.
For completeness' sake, this zip archive also contains the missing Gerber file for a backside legend layer for the main PCB, KiCadtop-B.SilkS.gbo. The original design data package had no backside legend because the Eurocircuits PCBproto process by default has no backside legend. However, the extra costs for adding a backside legend are only 0 euros, which is negligible compared to the total costs of the project. Besides, people may want to use other PCB manufacturers.
With one exception, the generated FIR filters and FIFOs used in version 2.1 of the valveDAC Verilog code are exactly the same as those used in version 1. See the documentation of version 1 to see how to generate them. (Again this is only relevant if you want to change something and, hence, can't use the MCS file.)
The exception is the filter type firdsd6 that is used at two places in module prefilter.v. These are generated by the Xilinx FIR compiler version 5.0 with exactly the same settings, coefficient file et cetera as the original firdsd filters (used in version 1 of the valveDAC Verilog code, see the documentation of version 1), except that the input word length is changed from 2 bits to 6 bits. (This automatically also results in a four bits longer output word length.)
The extra I2S input is mapped to these extension connector pins:

P9 pin 1: sel4192in, 0 selects the I2S (or raw DSD) input, 1 selects the DIX4192 S/PDIF interface. Debounced input with internal pull-up that can be connected to a fifth contact of the source selection switch.

P9 pin 3: mutei2sin, 1 mutes the sound when it comes from the I2S input.

P9 pin 5: datai2sin, I2S audio data input or raw DSD left audio data input.

P9 pin 7: deemni2sin, low level activates 50 us/15 us de-emphasis when the I2S input is active.

P9 pin 9: bcki2sin, bit clock for the I2S or raw DSD input.

P9 pin 11: lrcki2sin, word clock for the I2S input or right channel raw DSD data.

P9 pin 13: dsd64_128, must be 0 for DSD64 and 1 for DSD128 when the raw DSD interface is used.

P9 pin 15: dsdon, must be 0 for PCM or DoP, 1 for raw DSD.

P9 pins 2, 4, 6, 8, 10, 12, 14, 16: ground

P9 pins 17, 18, 19, 20: 3.3 V supply pins, see the schematic.

All inputs have internal pull-ups except dsdon and dsd64_128, which have internal pull-downs. The extension connector can be left unconnected when the I2S input isn't needed.
The logic high level is nominally 3.3 V. The logic high level can be reduced if needed by changing the power supply voltage of FPGA I/O bank 0. In principle the levels in the UCF file then have to be updated and everything has to be re-synthesized and re-implemented, but if you are lucky it might work without that.

A .zip with all modified files can be downloaded for free.

Appendices for Rudolf Moers' V13 article An investigation into the screen tap

Rudolf has published earlier articles in Linear Audio related to finding the lowest distortion solution for an ultra-linear circuit. However, on closer examination it turned out that his solution provided the most linear anode characteristic, which is not the same as lowest THD. In this article the author leads you through his investigation and the hidden arguments why the lowest THD is achieved at a certain screen grid tap. Not all material could be published in the article, and Rudolf added several Appandices which are posted here as PDF. Recommended reading!

Addendums to Ian Hegglun's CubeA and Current Source Driven output stage amplifiers (Vol 8 & Vol 13)

Ian Hegglun has published his Cube Law amplifier in Volume 8 and returned in Volume 13 with a CSD (Current Source Driven) output stage. Ian builds on several earlier publications to improve on the concept. He maintains a PDF addendum to his article(s) documenting his progress on further developments, insights and measurements. Please see also the Oops section on any corrections to the original article.

There is also a discussion thread on this subject at

This is one of those very rare occasions when something really new is proposed for audio power amplification - thank you Ian!

Hans Polak Non-plus-ultra Phono pre Vol 12

Linear Audio Vol 12 contains an article by Hans Polak on the design of a 'non-plus ultra' phono preamp. Hans has kindly agreed to make the PCB layout Gerber files available for interested readers.

Update: after several requests for an MM-version, Hans has worked out some changes to the original design to make it a better fit for MM cartridges. Here are the changes, which only affect the input stage:

  • 2x AD797 to be replaced by  2x OPA1641, matching these op-amps is not necessary;
  • R3 becomes 165 Ohm instead of 15 Ohm;
  • R4 becomes 47K instead of 1K;
  • R8 becomes 47pF instead of 111Ohm, which may be a better value for optimum damping of your cartridge, but you may have to adjust it to your cartridge;
  • R7 becomes 100pF, for the same reason as above;
  • C32 and C33 change from 220pF to 120pF, or possibly lower depending on the required capacity for your MM cartridge and the tonearm cable;
  • C21 & C22 (both 47pF) are no longer required.

With these changes, the SNR figures are:

  • Input shorted: 80.7 dBA ref 5mv @5cm/sec;
  • With cartridge connected: 76.5 dBA ref 5mv @5cm/sec.

PCB for Bob Cordell´s KT88 tube amp from Vol 2

Bob Coldell´s high quality KT88 tube amp article in Vol 2 generated quite some interest. In fact, I had a friend build one for myself! I designed a small PCB to hold the input and driver stages, to keep te construction clean and repeatable. For those who want to build it too, here are the particulars of the PCB and the circuit it holds:

Input and driver stages

PCB layout and stuffing

PCB Gerbers

Finally, here is the complete article.

Note: one reader has produced a few PCBs; if you are interested, let me know.

Worksheets and simulation files for Chris Paul's What's Mu with you? Volume 12

Chris Paul's article looked in much detail into the aspects of Mu followers and related circuitry. Chris developed a spreadsheet and an LTspice file that enabled him (and you) to explore the impact of various variables as explained in the article.

The spreadsheet and LTspice file and instructions can be downloaded here for personal use. Enjoy!

Exploration spreadsheet

LTspice simulations

LTspice simulation instructions

Thermal spreadsheet for John Escallier's Volume 9 article

The article by John Escalier in Volume 9 'Semiconductor junction dissipation and temperature -  theory and practice' discussed a spreadheet, developed by John, to facilitate calculating the various parameters for thermal management.

John has been so kind to make the spreadsheet available for L|A readers. It can be downloaded here.

Effective tip mass for record replay cartridges

Follwing the publication of Volume 10 which contained several articles concerning record replay, John Jones send author Hannes Allmaier and yours truly a long list of effective tip mass data for many well-known cartridges. I reproduce the list here, with thanks to John!

Any additional data would be quite welcome!

6.000mg ELAC STS-200 (1958, first stereo MM pickup?? 4-6g VTF)
6.000mg GE VR-II (1955, mono, variable reluctance, 4-7g VTF)
4.500mg Sonotone 9T (1960, stereo, ceramic)
3.000mg Philips GP316 (1958, crystal, mono, 5-7g VTF)
1.400mg Philips GP380/GP390 (1968, high fidelity ceramic cartridge)
1.200mg Shure V15 first generation (MM)
1.000mg Ortofon SPU (all classic and 'mono' models)
0.970mg Shure "bi-radial" (0.4x0.7mil, MM)
0.800mg (less than) Philips GP400, 401 1st gen (MM)
0.750mg Ortofon X1-MCP (p-mount, high output MC)
0.600mg Nagaoka JT-555 (pseudo "carbon fiber" cantilever)
0.600mg (less than) Philips GP412 1st gen (MM)
0.500mg Ortofon OM10 stylus (bushed elliptical, MI)
0.500mg Philips GP922 (high end MC)
0.450mg Shure V15-II (MM)
0.400mg Ortofon OM20 stylus (nude elliptical, MI)
0.700mg Ortofon X5-MC (HOMC, nude FG)
0.370mg Shure Elliptical (0.2x0.7mil, MM)
0.330mg Shure bi-radial on V15-III (MM) (berillium control rod)
0.300mg Ortofon OM30 stylus (nude Fine Line), OM40 (nude FG), MI
0.290mg Technics EPC-P202C (p-mount, MM, boron cant)
0.290mg Shure HE on V15-IV (MM) ("telescopic shank")
0.270mg Denon DL-301 (MC)
0.250mg Denon DL-207 (MC)
0.240mg Van den Hul Colibri (MC)
0.230mg Technics EPC-P310MC (p-mount, MC, boron cant)
0.230mg Technics EPC-100CMK2 (MM, boron pipe)
0.220mg Ortofon Jubilee (MC)
0.200mg Empire 2000-Z (shielded moving iron, stylus 0.2 mil x 0.7 mil diamond)
0.180mg Denon DL-303 (MC)
0.170mg Shure Micro-Ridge (0.15x3.00mil, MM, beryllium cant)
0.168mg Denon DL-305
0.149mg Technics EPC-(P)205CMK3 (MM, boron pipe)
0.139mg Technics EPC-P310MC2 (MC, boron pipe)
0.109mg Technics EPC-(P)205CMK4 (0.2x0.7mil, MM, boron pipe)
0.098mg Technics EPC-100CMK3 (MM, boron pipe)
0.077mg Denon DL1000 (MC, boron cant.)
0.055mg Technics EPC-(P)100CMK4 (MM, boron pipe cant.)

Test waveforms for Scott Wurcer's digital RIAA article in Volume 10

The following collection of test- and source files was submitted by Scott Wurcer to complement his article on Volume 10 on digital RIAA correction.

For those of you who wish to download the material, there is a pair of .zip files at the end which contain all the files and matrial posted here.

FIR Filters for RIAA

There are several sets of files containing minimum phase FIR filter coefficients for RIAA equalization in both text and wav format. There are files for 48K, 96K and 192K sampling rates as well as duplicates employing the extra 50K time constant that some recommend to compensate for cutter head roll-off/phase. The text files are in the SoX .dat format as shown below.

; Sample Rate 48000
; Channels 1
0.000000000e+00 5.966590663e-08
2.083333333e-05 -5.982466236e-08
4.166666667e-05 5.998405294e-08
6.250000000e-05 -6.014408199e-08

Here the first two lines contain the sample rate and the number of channels and each subsequent line contains the sample time and value at that time. Excel can be set to import just the second column skipping the first two lines from its import dialog so a simple text file of just the coefficients can be easily created. The files all have the peak value and hence the processing delay at different points, in general a slight delay which is equal in both channels does not matter for the purpose of simply listening. The text version of the files are all normalized to 1.0 so the peak can be found by a simple search in the second column if this is important in a particular application.

SoX Batch Files

It’s very easy to create a drag and drop .bat file to facilitate file conversions and other signal processing in SoX. It only requires an awareness of a small subset of DOS batch file commands and syntax. For instance, to convert a .wav file to a .dat (plain text) file one would do this…

cd %~dp0
FOR %%A IN (%*) DO sox -D %%A %%~nA.dat

When you drag a set of files onto this batch file ~dp0 contains the directory that the batch file is in and you cd to that directory first. Then for each file in all the files dropped run sox with no dither (-D) and save the result in this directory as a .datfile with the same name. Whenever possible SoX uses the file extension to figure out the “right thing” to do so dropping a .wav file results in the simple translation of .wav to .dat with no dither. There are many web resources for translating the sometimes cryptic batch file syntax, and the SoX manual describes building a command line which can include both IIR and FIR filters as well as several options for adjusting gain or normalization of the output. The reverse process…

cd %~dp0
FOR %%A IN (%*) DO sox -D %%A -e signed -b32 %%~nA.wav gain -2

Here we read a .dat file and set the output format to 32bit signed integers, the highest resolution 32 bit format. I have set the gain to 2dB below full scale for .wav files because I have run across some low cost sound cards that clip internally with files that go to full scale. For both of these SoX has to be in your $path or the same folder as the batch file.

min_phase_FIR_RIAA_48k.dat    min_phase_FIR_RIAA_96k.dat   min_phase_FIR_RIAA_192k.dat

min_phase_FIR_RIAA_48k.wav   min_phase_FIR_RIAA_96k.wav   min_phase_FIR_RIAA_192k.wav

min_phase_FIR_RIAAp50_192k.dat   min_phase_FIR_RIAAp50_96k.dat   min_phase_FIR_RIAAp50_48k.dat

min_phase_FIR_RIAAp50_48k.wav   min_phase_FIR_RIAAp50_96k.wav   min_phase_FIR_RIAAp50_192k.wav

The following two batch files facilitate conversion of one file type to the other:  dattowav.bat      wavtodat.bat

Test Waveforms

These folders contain test waveforms (all in .wav format) with several possible uses. All files come in both a 48kHz and 96kHz versions. They are based on the concept of spectral contamination in the presence of a noise or music like stimulus. The first set consists of four multi-tone files where there are 30 tones at 1/3 octave spacing with random phases. In the time domain it sounds a little like one big 6 handed chord. There are both a general use, flat, version and a version with RIAA pre-emphasis applied which can be used as a simple test for RIAA conformance. The numerical noise filling the space between the tones is below the noise floor of a 24 bit DAC so any imperfections in the signal path will fill the space between the tones with IM/THD components. The files with a flat spectrum are generally useful for DAC/ADC testing as well as any amplifier/speaker chain. It may be difficult to find a DAC or ADC to reproduce these without excessive spectral contamination of their own, in that case a comparative analysis might be useful. These file are designed to be analyzed with a 65536 point FFT and with no (rectangular) windowing though some window functions have low enough leakage to still be useful. With any other length FFT the relationship of the tones to the FFT bins is lost. The next two folders contain pseudo-random noise waveforms containing equal energy at every FFT bin but again with random phase so the resulting time domain waveform looks and sounds like random noise. Each waveform comes in versions with all tones and with four logarithmically spaced gaps to again do the spectral contamination test, and with or without RIAA pre-emphasis for a total of eight files. Since the RIAA pre-emphasized files see the full 40dB of the RIAA curve and do not take into account that the spectral content of most music rolls off with frequency, they are an extreme test of your signal path.

30 tone multitone test files:                30multitone_IRIAA_96.wav   30multitone_flat_96.wav             30multitone_IRIAA_48.wav   30multitone_flat_48.wav

pseudo-noise flat test files:                  psrnoise_flat_48.wav            psrnoise_flat_48_holes.wav        psrnoise_flat_96.wav            psrnoise_flat_96_holes.wav

pseudo-noise_inverse RIAA test files:  psrnoise_IRIAA_48.wav        psrnoise_IRIAA_48_holes.wav    psrnoise_IRIAA_96.wav       psrnoise_IRIAA_96_holes.wav

Coefficient tables

To close this section, here are the tables with filter coefficients as shown in the Article Appendix. If you want to play with them you can cut-'n-paste from these files:

v10 sw appendix a tables      v10 sw appendix b tables

Python functions and filter Optimizer

This is a very basic example of using scipy’s brute force optimizer to optimize the z domain poles and zeros to match an s domain prototype filter. Since the optimizer starts by doing an exhaustive search over a range of values for any number of variables, this becomes very slow rapidly as the number of variables or fineness of the search grid grows. This example is set up for a peaking equalizer where the gain , Q, and frequency of interest (fo) are specified. I suggest the reader familiarize themselves with the optimizer by reading the online description as well as The Audio EQ Cookbook.
The function fun(x) is minimized by the optimizer via the array (x) of variables. Here x[0] is fo, x[1] is A (gain), and x[2] is Q. The poles and zeros are extracted as the roots of the characteristic polynomial and the peak to peak error between the z domain response and the s domain response is returned.
The values in the body of the routine will need to be edited for different frequencies, other parameters, and different types of filters. Start and stop give a range of frequencies over which to optimize. The ranges are the set of ranges for the array of variables (x) passed by the optimizer (brute()). I use these to multiply the filter parameters so (.8, 1.2) is an ~ +- 20% range while the variable Ns is the fineness of the search. There is lots of room for experimentation with the values that are left up to the user.
The optimizer returns the optimized values for the x array which are then used to compute the optimized poles and zeros and the coefficients for the IIR filter which are printed out at the end.
This example is for a 5dB, 10kHz peaking filter with a Q of .5 and a sampling frequency of 48kHz. I chose to optimize only to 12kHz because increasing this rapidly degrades the fit due to the frequency warping. In fact it is easy to get no better a fit than by simply using the suggested “tweek” to the Q mentioned in the main article. Running the script generates output which consists of the poles and zeros of the prototype followed by the optimum z domain poles and zeros with the computed IIR filter coefficients. note: rename to to run!

Python functions library

These are the basic functions that I use to go back and forth between the s and z domain, compute IIR coefficients and plot phase and frequency responses. As mentioned in the article I am not a programmer by trade and there are probably many improvements possible here. It is easy with Python to get a little confused around arrays, lists, and other ways of packing and unpacking data. Usually what seems obvious works but there are times when an explicit declaration is necessary. Also there is not thorough checking for bad inputs so they will simply fail or give a bad output. As noted also I use positive frequency for both the s and z domain in my computations, the built-in roots() function returns negative values as it should and they are inverted as necessary in my code.

dB(x) - Returns 20*log10(abs(x)) for any length argument.

f_warp(f, fs) – Returns the “warped” frequency of interest (f) for IIR filter coefficients. Fs is the sampling frequency.

f_from_z(z, fs) – Returns a frequency from the point z inside the unit circle.

z_from_f(f, fs) – Returns the point z inside the unit circle corresponding to frequency f.

Fs_at_f(Poles, Zeros, f, norm = 0) – Returns the complex value/s for s domain frequency response at list of frequencies f. The transfer function is described by its poles and zeros. If norm is true (1) the output is normalized to 1 at the maximum value.

Fz_at_f(Poles, Zeros , f, fs, norm = 0) – Returns the same for the z domain poles and zeros (here fs is needed also). The pole and zero frequencies are those that would be returned from f_from_z(z, fs).

z_coeff(Poles, Zeros, fs, g, fg, fo = 'none') – Returns the a and b coefficients of the IIR filter defined by the poles and zeros. G and fg are the gain in db and frequency at which that gain is set. Fo is the frequency of interest, that is, for a peaking filter fo would be the peak while for a low pass or high pass filter it would be the break point. If ‘none’ or not specified there is no frequency warping and all mapping is simply by the bilinear transform.

biquad_filter(xin, z_coeff) – Returns xin filtered by the biquad filter defined by the z domain coefficients, [[a0, a1, a2] ,[ b0,b1,b2]]. By convention the b coefficients are the numerator and the a are the denominator with a0 = 1.

write_txt(filename, y) – Writes a simple text file of the values of the array y.

read_txt(filename) – Returns an array from the values in a text file.

read_dat(filename) – Returns a mono or stereo file in the SoX .dat format.

write_dat(filename, sr, left, right='none') – Writes a file in the SoX .dat format. Sr = the sample rate. Left and right are equal sized arrays of time samples.

plot_fft_log(fs, data, diff = 'none', start = 0,stop = 0, delay = 0) – Plots the FFT of a time domain waveform. Fs is the sampling frequency and data are the samples. If diff is specified the difference between data and diff is plotted. Start and stop are the start and stop frequencies for the plot, 20Hz and 20kHz are the defaults. A delay in samples is specified to compensate for phase wrapping, the default is 0. This function compensates for actual bin frequencies so, for example, a 65536 point FFT of a waveform sampled at 48kHz gives the right frequencies.

plot_fft_lin(fs, data,diff = 'none', start = 0, stop = 0, delay = 0) – Same function for a linear with frequency plot.

plot_dat(sound) – Plots a sound file read by read_dat() or in the .dat format.

plot_gain_phase(Poles, Zeros, zPoles = [], zZeros = [], fs = 48000.,fo = 1000. ,start = 20, stop = 20000,style = 0) – Plots the gain and phase vs frequency of a frequency response defined by a set of Poles and Zeros. If zPoles and zZeros are specified it becomes a comparison between the s and z domain with fs being the sampling frequency. Fo is the frequency where both responses are equalized. Start and stop are again the limits on the plot while style = 1 is a difference plot and style = 0 is a plot of both responses on the same axes.

min_phase_FIR(Poles, Zeros, fs, outfile, plot = 0) – Generates a minimum phase FIR filter in mono .dat format from the s domain poles and zeros at a sampling frequency fs. The output is written to ‘outfile’ and it expects a HOME directory to exist. You can change the code to output to whatever you want. Plot = 1 plots the result so you can examine it. note: rename to to run!

All test- and data waveform files                     All Python optimizer example&source files

Design considerations for a class A enclosure.

EUVL's class A enclosure

Patrick K. (aka EUVL) wrote an interesting article for Vol 3, "Design Considerations for a Class A Amplifier Enclosure". This is an subject that is very rarely treated at all. The article gives a complete treatment of all involved issues and can be used as a procedure to calculate the required heatsink capacity for a project, as well as selecting a suitable product to mee those requirements. Therefor, Patrick and I have agreed to place it online for further dissemination.

'The LTspice IV Simulator' by Gilles Brocard, reviewed by Bob Cordell

Linear Technoloy's LTspice simulator is a free, very high performance Spice simulator that is very much appreciated by professional designers and serious hobbyists alike. Gilles Brocart has written an extensive book with reference material, applications information and simulation methods. The book has a preface by LTspice's development manager Mike Engelhardt.

Bob Cordell, an avid LTspice user himself, has reviewed this book for Linear Audio Volume 9.

The review is available for download free of charge. The book itself is published by Würth Electronic but they have agreed to make it available for Linear Audio readers in an English and a German version. You can get it in our store for slightly less than at the other places... ;-) .

PCBs for Stuart Yaniger's Equal Opportunity phono preamp / gain block

In his Volume 7 article Staurt presented a universal gain block, with a particular application to phono preamps. Because it uses JFETs, tubes, MOSFETs and IC regulators, it was baptised 'The Equal Opportunity gain block'.

I designed a PCB layout for the gain block with positions for RIAA corrction components, and the board files and relevant schematics are available here for anyone whoi want to buiild it, as long as it is not for a commercial purpose. If you want to commercialise it, please check with Stuart for license arrangements.

Main schematic

Power Supply

Stuffing Guide

PCB Gerbers

Additional material for Hegglun Cube Law power amp

In his Volume 8 article on Cube Law power amplifiers Ian Hegglun mentions that he has a lot of additional information available on the subjet. This additional info can be accessed on line courtesy of Mason Green. There's even more info and also the possibility to get additional PCBs from Mason at his own site.

As if that is not enough, there's more interesting info Ian collected including simulation models and files to simulate his amp with LTspice...

Appendices Audio Equalisation

In his article on Audio Equalisation in Volume 7, Malcolm Hawksford provided three Appendices. These contain Matlab scripts that can be used to explore the various circuit concepts described in the article.

Those Appendices can be downloaded in text format for immediate use in Matlab or any of it's equivalent applications.

Testing One, Two, Three...

Stuart Yanigers' Linear Audio Volume 2 article with this title has drawn considerable interest from both audio professionals as well as serious amateurs and hobbyists.

Many readers requested to make it available on line, so here it is.

LSJ74B preliminary data sheet

Linear Systems has send me the preliminary data sheet for the LSJ74B, the long-awaited replacement for the discontinued Toshiba 2SJ74B. This is posted here for the benefit of those who purchased Linear Audio Vol 6 asnd received a free LSJ74B and LSK170B.

Power Supply for Gary Galo's Archival Phono Preamp

Gary Galo's article in Vol 5, "An Archival Phono Preamp" mentioned that a suitable power supply would be posted online - here it is.

It is based on the Jung/Didden regulator published in Audio Amateur in 1995, amended by Walt Jung's article in issue 4/2000 in Audio Xpress. The original articles can be downloaded from Walt's web site.

Gerbers and PCB layout for Bruno Putzeys' article in Vol 5

The article from Bruno Putzeys in Vol 5 'The G-word, or, how to get your audio off the ground' is accompanied by a complimentary PCB for the demo project (courtesy It's a busy PCB and to help with parts placement, a larger version of the stuffing guide, the top layer and the bottom layer is available here. The Gerbers can also be downloaded if you want to make your own.

Color graphs for Jack Walton's regulator article in Vol 4

Linear Audio Volume 4 has a long-awaited article by Jack Walton, comparing a large number of low power supply regulators. Comparison includes measurements and controlled listening tests by the New Jersey Audio Club.

The article has a several rather busy graphs with curves in various shades of grey. The readability could be better, so I regenerated those graphs in color and posted them here on-line.

Fig 5, positive regulators Line Rejection

Fig 6, negative regulators Line Rejection

Fig 7, positive regulators Output Noise

Fig 8, positive regulators Output Impedance

Fig 9, negative regulator Output Impedance

MathCad resources for the audio enthousiast

Update 5 July 2012: Mason Green send me some info on an alternative to MathCad/MatLab: Scientific Python. He included a link to an excellent tutorial on Scientific Python. For an example of a practical application of Scientific Python, see Mason's PORC (Python Open Room Correction) project. Thank you Mason!

There have been several articles in Linear Audio supported by MathCad calculations and graphs; Burkhard Vogel's articles come to mind. If you are the curious type you probably discovered that a MathCad license can set you back $ 1500 or so. Not really DIY territory. However, here's a well kept secret: the student/educational version of MathCad is available for less than $ 100 and is identical to the expensive version, the only difference being that you don't get on-line support. And you need a professor- or student ID to be able to buy that version.

But it gets still better: if you buy Brent Maxfields'book Essential MathCad for Engineering, Science and Math for less than $ 50 you get an included MathCad 15 one-year student license for free. And the book is a great reference to the application so you can do without the on-line support. For beginners, I recommend Stephen P. Tubbs' MathCad for Electrical Engineers and Technologists. This last book takes you in slowly with calculating and graphing things like the current in a C-R circuit, for example. Both books are highly recommended! Note: the Maxfield book was published in 2009 so I don't know how many copies are still on offer.

Audio files for Wurcer mic preamp article V1, V3.

The mic preamp Scott Wurcer developed in his articles in Vol 1 (Part I) and Vol 3 (Part II) were used to record a live concert at Stuart Yaniger's residence in Austin, TX in Nov 2011. I have placed two files online, and you can download them to listen to: the song 'An Army of Kittens' (a 15Mb (!) .flac) and a section of the subsequent applause (.wav). These are uncompressed files recorded in 24 bit / 96kHz.

These are excellent examples of the incredible realistic recordings that can be made with relatively simple means, with enough attention to detail. Files are reproduced here with kind permission from the artist, Southpaw Jones.

Zen > Cen > Sen - Evolution of a Minimalistic IV Conversion Circuit

This is the online version of Patrick K (alias EUVL) article in Linear Audio Vol 2. This article has generated considerable interest at diyaudio and with the publication of Vol 3 I have decided to place this article online for free download. For further details and building experiences, see the diyaudio thread.

Everything about record replay characteristics, recording speeds and such.

This is not an article that has been published in Linear Audio, but I believe the data in the linked table is of importance to anyone seriously involved with record replay and reproduction, especially historical records.

The first reference is a comprehensive list of record manufacturers and speed formats and the pre-emphasis that has been used in producing the recording. It is clear that the ubiquitous RIAA pre-emphasis/ de-emphasis standard isn't really a standard, at least not in the early days of records.

The list has been compiled by Katsuyoshi Miguchi, the owner of SoundBox, an Antique Audio shop in Tokyo. It was originally published in Radio Technology magazine in Japan in October 2011. Reproduced here by kind permission of the Author and the Editor of RT magazine. I am indebted to Mr. Nakamura for arranging the permissions and for providing the English language translation.

If you have any additions and/or corrections to this table I would very much like to receive these, and I will update the list as needed. The last update will be noted at the end of the list.

The second reference is an article by Linear Audio author Gary Galo, who taught audio engineering at the Crane School of Music at SUNY, Potsdam. Gary wrote an article for the Association for Recorded Sound Collections (ASRC) on the Columbia replay equalisation curve.

The Association kindly agreed to place this article online. The powerpoint slides Gary uses for his presentations on the subject is also attached.

The F-Word - or, why there is no such thing as too much feedback

In Linear Audio Volume 1, Bruno Putzeys wrote  The F-word - or, why there is no such thing as too much feedback. He addresses many issues related to the use of feedback in audio, as well as several misconceptions. The section on 'slow' and 'fast' amplifiers will be an eyeopener for many. He also traces historical events that puts us in the situation we are now. A critical attitude towards negative feedback is certainly healthy, and Bruno gives us the information to base our opinion on.

The Arch Nemesis

The first issue of Linear Audio had an article by Nelson Pass inspired by a vintage Western Electric design, later revived by Jean Hiraga in the French journal L'Audiophile. It's a model of minimalistic design and I placed it on-line for you to read and/or build. Nelson Pass - The Arch Nemesis (Vol 0)


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text:
Routing-based navigation of dense mobile robots

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In the future, many teams of robots will navigate in home or office environments, similar to dense crowds operating currently in different scenarios. The paper aims to route a large number of robots so as to avoid build-up of congestions, similar to the problem of route planning of traffic systems. In this paper, first probabilistic roadmap approach is used to get a roadmap for online motion planning of robots. A graph search-based technique is used for motion planning. In the literature, typically the search algorithms consider only the static obstacles during this stage, which results in too many robots being scheduled on popular/shorter routes. The algorithm used here therefore penalizes roadmap edges that lie in regions with large robot densities so as to judiciously route the robots. This planning is done continuously to adapt the path to changing robotic densities. The search returns a deliberative trajectory to act as a guide for the navigation of the robot. A point at a distant of the deliberative path becomes the immediate goal of the reactive system. A ‘centre of area’-based reactive navigation technique is used to reactively avoid robots and other dynamic obstacles. In order to avoid two robots blocking each other and causing a deadlock, a deadlock avoidance scheme is designed that detects deadlocks, makes the robots wait for a random time and then allows them to make a few random steps. Experimental results show efficient navigation of a large number of robots. Further, routing results in effectively managing the robot densities so as to enable an efficient navigation.

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  1. 1.

    Choset H, Lynch KM, Hutchinson S, Kantor GA, Burgard W, Kavraki LE, Thrun S (2005) Principles of robot motion: theory, algorithms, and implementations. MIT Press, Cambridge

  2. 2.

    Tiwari R, Shukla A, Kala R (2013) Intelligent planning for mobile robotics. IGI Global Publishers, Hershey

  3. 3.

    Chand P, Carnegie DA (2012) A two-tiered global path planning strategy for limited memory mobile robots. Robot Auton Syst 60(3):309–321

  4. 4.

    Kala R, Shukla A, Tiwari R (2010) Fusion of probabilistic \(\text{ A }^{*}\) algorithm and fuzzy inference system for robotic path planning. Artif Intel Rev 33(4):275–306

  5. 5.

    Kavraki LE, Svestka P, Latombe JC, Overmars MH (1996) Probabilistic roadmaps for path planning in high-dimensional configuration spaces. IEEE Trans Robot Autom 12(4):566–580

  6. 6.

    Bohlin R, Kavraki LE (2000) Path planning using lazy PRM. In: Proceedings of the IEEE international conference on robotics and automation, pp 521–528

  7. 7.

    Claes R, Holvoet T, Weyns D (2011) A decentralized approach for anticipatory vehicle routing using delegate multiagent systems. IEEE Trans Intell Transp Syst 12(2):64–373

  8. 8.

    Kala R, Warwick K (2015) Congestion avoidance in city traffic. J Adv Transp 49(4):581–595

  9. 9.

    Spears WM, Spears DF, Hamann JC, Heil R (2004) Distributed, physics-based control of swarms of vehicles. Auton Robot 17(2–3):137–162

  10. 10.

    Pelechano N, Allbeck JM, Badler NI (2007) Controlling individual agents in high-density crowd simulation, In: Proceedings of the 2007 ACM SIGGRAPH/Eurographics symposium on Computer animation, pp 99–108

  11. 11.

    Musse SR, Thalmann D (2001) Hierarchical model for real time simulation of virtual human crowds. IEEE Trans Virtual Comput Graph 7(2):152–164

  12. 12.

    Curtis S, Best AP, Manocha D (2016) Menge: a modular framework for simulating crowd movement. Collect Dyn 1(A1):1–40

  13. 13.

    Gu Q, Deng Z (2011) Context-aware motion diversification for crowd simulation. IEEE Comput Graph Appl 31(5):54–65

  14. 14.

    Kountouriotis V, Thomopoulos SCA, Papelis Y (2014) An agent-based crowd behaviour model for real time crowd behavior simulation. Pattern Recogn Lett 44:30–38

  15. 15.

    Han Y, Liu H, Moore P (2017) Extended route choice model based on available evacuation route set and its application in crowd evacuation simulation. Simul Model Pract Theory 75:1–16

  16. 16.

    Golas A, Narain R, Curtis S, Lin MC (2014) Hybrid long-range collision avoidance for crowd simulation. IEEE Trans Vis Comput Graph 20(7):1022–1034

  17. 17.

    Cowlagi RV, Tsiotras P (2012) Hierarchical motion planning with dynamical feasibility guarantees for mobile robotic vehicles. IEEE Trans Robot 28(2):379–395

  18. 18.

    Sgorbissa A, Zaccaria R (2012) Planning and obstacle avoidance in mobile robotics. Robot Auton Syst 60(4):628–638

  19. 19.

    Chang YC, Yamamoto Y (2009) Path planning of wheeled mobile robot with simultaneous free space locating capability. Intell Serv Robot 2(1):9–22

  20. 20.

    Yao Z, Gupta K (2011) Distributed roadmaps for robot navigation in sensor networks. IEEE Trans Robot 27(5):997–1004

  21. 21.

    Clark CM (2005) Probabilistic road map sampling strategies for multi-robot motion planning. Robot Auton Syst 53:244–264

  22. 22.

    Chai R, Su J (2013) Motion planning for multi-robot coordination. In: 13th IFAC symposium on large scale complex systems: theory and applications, Shanghai, China, pp 129–134

  23. 23.

    Alvarez-Sanchez JR, de la Paz Lopez F, Troncoso JMC, de Santos Sierra D (2010) Reactive navigation in real environments using partial center of area method. Robot Auton Syst 58(12):1231–1237

  24. 24.

    Sezer V, Gokasan M (2012) A novel obstacle avoidance algorithm: follow the gap method. Robot Auton Syst 60(9):1123–1134

  25. 25.

    Kim Y, Kwon SJ (2015) A heuristic obstacle avoidance algorithm using vanishing point and obstacle angle. Intell Serv Robot 8(3):175–183

  26. 26.

    Fiorini P, Shiller Z (1998) Motion planning in dynamic environments using velocity obstacles. Int J Robot Res 17(7):760–772

  27. 27.

    Snape J, van den Berg J, Guy SJ, Manocha D (2011) The hybrid reciprocal velocity obstacle. IEEE Trans Robot 27(4):696–706

  28. 28.

    Rashid AT, Ali AA, Frasca M, Fortuna L (2012) Multi-robot collision-free navigation based on reciprocal orientation. Robot Auton Syst 60(10):1221–1230

  29. 29.

    Karagoz CS, Bozma HI, Koditschek DE (2014) Coordinated navigation of multiple independent disk-shaped robots. IEEE Trans Robot 30(6):1289–1304

  30. 30.

    Zhong J, Cai W, Lees M, Luo L (2017) Automatic model construction for the behaviour of human crowds. Appl Soft Comput.

  31. 31.

    Patil S, van den Berg J, Curtis S, Lin MC, Manocha D (2011) Directing crowd simulations using navigation fields. IEEE Trans Vis Comput Graph 17(2):244–254

  32. 32.

    Hsu D, Sanchez-Ante G, Sun Z (2005) Hybrid PRM sampling with a cost-sensitive adaptive strategy. In: Proceedings of the 2005 IEEE international conference on robotics and automation, Barcelona, Spain, pp 3874–3880

  33. 33.

    Rodriguez S, Thomas S, Pearce R, Amato NM (2008) RESAMPL: a region-sensitive adaptive motion planner. In: Algorithmic Foundation of Robotics VII, Springer Tracts in Advanced Robotics. Springer, Berlin, pp 285–300

  34. 34.

    Morales M, Tapia L, Pearce R, Rodriguez S, Amat NM (2005) A machine learning approach for feature-sensitive motion planning. In: Algorithmic Foundations of Robotics VI, Springer Tracts in Advanced Robotics, Springer, Berlin, vol 17, pp 361–376

  35. 35.

    Kala R (2016) Homotopy conscious roadmap construction by fast sampling of narrow corridors. Appl Intell 45(4):1089–1102

  36. 36.

    Hsu D, Jiang T, Reif J, Sun Z (2003) The bridge test for sampling narrow passages with probabilistic roadmap planners. In: Proceedings of the 2003 IEEE international conference on robotics and automation, vol 3, pp 4420–4426

  37. 37.

    Amato NM, Bayazit OB, Dale LK, Jones C, Vallejo D (1998) Obprm: an obstacle-based prm for 3d workspaces. In: Agarwal P, Kavraki LE, Mason M (eds) Robotics: the algorithmic perspective. A.K. Peters, Natick, pp 155–168

  38. 38.

    La Valle SM, Kuffner JJ (2001) Randomized kinodynamic planning. Int J Robot Res 20(5):378–400

  39. 39.

    Kuffner JJ, LaValle SM (2000) RRT-connect: an efficient approach to single-query path planning. In: Proceedings of the IEEE international conference on robotics and automation, pp 995–1001

  40. 40.

    Russell S, Norvig P (2010) Artificial intelligence: a modern approach, 3rd edn. Pearson, Harlow

  41. 41.

    Helbing D, Molnar P (1995) Social force model for pedestrians dynamics. Phy Rev E 51(5):42–82

  42. 42.

    Martinez-Garcia E, Torres-Cordoba R (2012) Exponential fields formulation for WMR navigation. J Appl Bion Biomech 9(4):375–397

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Correspondence to Rahul Kala.

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Kala, R. Routing-based navigation of dense mobile robots. Intel Serv Robotics 11, 25–39 (2018) doi:10.1007/s11370-017-0243-8

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  • Motion planning
  • Navigation
  • Swarm robotics
  • Multi-agent systems
  • Routing
  • Probabilistic roadmap


text:
Overexpression of mitochondrial creatine kinase preserves cardiac energetics without ameliorating murine chronic heart failure

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Mitochondrial creatine kinase (Mt-CK) is a major determinant of cardiac energetic status and is down-regulated in chronic heart failure, which may contribute to disease progression. We hypothesised that cardiomyocyte-specific overexpression of Mt-CK would mitigate against these changes and thereby preserve cardiac function. Male Mt-CK overexpressing mice (OE) and WT littermates were subjected to transverse aortic constriction (TAC) or sham surgery and assessed by echocardiography at 0, 3 and 6 weeks alongside a final LV haemodynamic assessment. Regardless of genotype, TAC mice developed progressive LV hypertrophy, dilatation and contractile dysfunction commensurate with pressure overload-induced chronic heart failure. There was a trend for improved survival in OE-TAC mice (90% vs 73%, P = 0.08), however, OE-TAC mice exhibited greater LV dilatation compared to WT and no functional parameters were significantly different under baseline conditions or during dobutamine stress test. CK activity was 37% higher in OE-sham versus WT-sham hearts and reduced in both TAC groups, but was maintained above normal values in the OE-TAC hearts. A separate cohort of mice received in vivo cardiac 31P-MRS to measure high-energy phosphates. There was no difference in the ratio of phosphocreatine-to-ATP in the sham mice, however, PCr/ATP was reduced in WT-TAC but preserved in OE-TAC (1.04 ± 0.10 vs 2.04 ± 0.22; P = 0.007). In conclusion, overexpression of Mt-CK activity prevented the changes in cardiac energetics that are considered hallmarks of a failing heart. This had a positive effect on early survival but was not associated with improved LV remodelling or function during the development of chronic heart failure.

Effective treatments for chronic heart failure often act to reduce cardiac energy demand by lowering afterload and/or heart rate (e.g. β-adrenergic antagonists, ACE inhibitors and diuretics). However, this approach is limited by the risk of bradycardia and hypotension, and an attractive alternative for new heart failure therapies is therefore to also improve myocardial energy supply [12, 34].

The creatine kinase (CK) phosphagen system has a central role in matching energy supply to energy demand and represents a potential target for therapeutic intervention. The mitochondrial isoform of CK (Mt-CK) is located within the mitochondrial intermembrane space, where it is functionally coupled to ATP production via the adenine nucleotide translocase (ANT). Mt-CK catalyses the transfer of a phosphoryl group from the newly generated ATP onto creatine to form phosphocreatine (PCr) and ADP (which stimulates further oxidative phosphorylation) [40]. PCr is relatively smaller and less polar than ATP allowing it to accumulate to higher levels and act as an energy transport and buffering system, capable of regenerating ATP when demand outstrips supply. This reaction is catalysed by cytosolic CK isoforms, such as muscle (M-CK), that are often functionally coupled to major ATP-using enzymes (e.g. myosin ATPase, SERCA) [40].

A substantial body of observational data in patients and animal models has implicated an impaired CK system in the pathophysiology of chronic heart failure (CHF) [15, 22], with both total creatine levels and CK activity reduced commensurate with disease severity (reviewed in [34]). This is most commonly observed in vivo as a fall in the PCr/ATP ratio using 31phosphorus-magnetic resonance spectroscopy (31P-MRS). For example, in patients with dilated cardiomyopathy, a low PCr/ATP was associated with higher mortality and correlated with New York Heart Association class and ejection fraction [35, 36].

However, whether loss of CK function has a causative role in the pathophysiology of CHF has yet to be proven. Genetic knockout studies in mice have suggested only mild or ambiguous effects on cardiac function, suggesting that a dysfunctional CK system, in itself, is usually insufficient to cause heart failure [5, 23, 24]. Even when loss of function has been superimposed on surgical models of CHF, the expected detrimental effects have not been obvious [13, 20, 32].

A complementary approach is to ask whether preventing energetic remodelling via augmentation of the CK system would be beneficial. Increasing myocardial levels of creatine protected against ischaemia–reperfusion injury (I/R), but did not improve outcomes in the setting of CHF [6, 21]. However, seminal evidence comes from overexpression of M-CK in mouse heart, which improved survival and contractile function in a model of pressure overload-induced CHF. Most convincingly, this was associated with preservation of ATP production via the CK reaction (CK flux), and protection was lost in a sub-group of mice where the transgene was turned off partway through the protocol [9].

The therapeutic potential for augmentation of Mt-CK in CHF has yet to be tested and, quite apart from it being a major determinant of PCr/ATP [49], there are good reasons to think that this approach may also be beneficial. Not least, is an effect to reduce opening probability of the mitochondrial permeability transition pore (mPTP), thereby preventing cardiomyocyte death [48, 50]. This is a key event governing I/R injury where Mt-CK overexpression has already been shown to be cardioprotective [48], and it is also thought to contribute to cellular loss in the chronically failing heart. Preserving mitochondrial health is an important goal in heart failure, and the close functional coupling between Mt-CK and oxidative phosphorylation is thought to promote this. A further contributory factor is likely the role of Mt-CK in promoting mitochondrial structural integrity by forming contact sites between the inner and outer membranes [40]. Finally, Mt-CK is particularly vulnerable to deactivation via reactive oxygen species [47], which are known to be elevated in the failing heart. Replacement of affected protein could prove beneficial, especially since Mt-CK activity closely correlates with recovery of LV function in post-ischaemic myocardium [2].

For the reasons outlined above, we hypothesised that overexpression of Mt-CK would be beneficial in terms of cardiac energetics, function and structural remodelling in a mouse model of pressure overload CHF. We utilised an existing strain of cardiac-specific Mt-CK-OE under control of the α-MHC promoter that was generated in our laboratory [48]. This used a cautious transgenic approach to increase myocardial Mt-CK activity by 25–30%, which had no measureable effect on baseline mitochondrial function, but was sufficient to provide protection against I/R injury.

Ethics statement and colony maintenance

All animal experiments were approved by the Committee for Animal Care and Ethical Review at the University of Oxford, and comply with Home Office Regulations incorporating the Animals (Scientific Procedures) Act of 1986 and Directive 2010/63/EU of the European Parliament (project licence number 30/3314). Mice were maintained in individually ventilated cages on a 12 h night/day cycle with controlled temperature (21 °C) and humidity. Mice were fed irradiated Global Diet 2916 (Envigo, Huntingdon, UK) and water ad libitum and housed with littermates in specific pathogen-free conditions. Creation of the cardiac-specific transgenic CK-Mt-OE line and genotyping protocol has been described previously [48]. This strain has been backcrossed for > 10 generations using C57BL/6JOlaHsd mice obtained from Envigo, Huntingdon, UK (formerly known as Harlan). For all experiments, transgenic mice were homozygote for CK-Mt overexpression and wild-type (WT) were non-transgenic littermates bred in our establishment.

Study design

Male WT and overexpressing (OE) mice aged 15 ± 3 weeks were randomly assigned to either transverse aortic constriction (TAC) or sham surgery to create four experimental groups: WT-Sham, OE-Sham, WT-TAC, and OE-TAC. All mice had an echocardiogram a few days before surgery (week 0) and at week 3 and week 6 post-surgery to assess onset of chronic heart failure. Left ventricular (LV) haemodynamics were assessed 2–3 days after the final echocardiogram, after which animals were killed by removal of the heart under terminal anaesthesia. LV tissue was washed briefly in physiological saline, blotted and weighed, then snap frozen using Wollenberger tongs in liquid nitrogen and stored at − 80 °C until use. An independent cohort of mice received TAC or sham surgery and were subjected to 31P-MRS for analysis of in vivo PCr/ATP ratio at 6 weeks post-surgery. Supplementary Table 1 shows animal numbers and fate for all experimental steps.

TAC surgery was performed aseptically as described previously under isoflurane general anaesthesia (2% in medical oxygen with anaesthetic depth assessed by loss of pedal reflex) [18, 27]. Buprenorphine analgesia was given subcutaneously immediately prior to surgery (0.8 mg/Kg) and again the morning after surgery (0.4 mg/Kg).

Echocardiography and haemodynamics

Mice were maintained on isoflurane anaesthesia (1.0–1.5% in medical O2), placed on a homeothermic table and parasternal short-axis B-mode views obtained at the level of the papillary muscles using a Visualsonics Vevo 2100 ultrasound system with 22–55 MHz transducer (MS 550D). Data analysis was performed by a single operator blinded to genotype using Vevo Lab, Edition 1.7.1 (Visualsonics, Toronto, Canada). Measurements were made directly from the 2-D images and are therefore expressed as areas.

Retrograde LV cannulation was performed under isoflurane anaesthesia via the right carotid artery using a 1.4F solid-state pressure catheter (SPR-839, Millar Instruments, Texas, USA) as described previously [5]. The jugular vein was cannulated using flame-stretch polyethylene tubing (Portex 0.96 mm OD, 800/100/200, Smiths Medical, UK) for administration of dobutamine hydrochloride at 16 ng/g BWt/min. Mice were killed at the end of the experiment by overdose of pentobarbitone.

Frozen LV tissue was powdered and total creatine (i.e. the sum of free creatine and phosphocreatine (PCr)) was quantified by HPLC [43]. Total creatine kinase (CK) and citrate synthase activities were quantified under saturating conditions using standard spectrophotometric techniques and relative CK isoenzyme activities via the SAS-1 gel electrophoresis system (Helena Biosciences, UK). Values were normalised to protein content measured by the Lowry method, as described previously [48]. The relative maximal velocity of the CK reaction was estimated by the product of enzyme activity and total creatine concentration, since these two parameters represent the numerators of the rate equation that vary the most under disease conditions and are therefore the primary determinants [14].

In vivo 31P-MRS

General anaesthesia was maintained using 1.5–2.0% isoflurane in oxygen with mice placed prone in a heated cradle with the heart directly over the surface coil array and ECG and respiratory gating [4]. All 31P-MRS data were acquired utilising a horizontal 9.4 T magnetic resonance system equipped with a Direct Drive2 console and 120 mm i.d., 0.6 T/m, shielded gradient set (Agilent Technologies, USA) operating at 400 MHz frequency for 1H and 168 MHz for 31P measurements. Images were acquired using a linear double-tuned, actively decoupled, 1H/31P 39 mm birdcage resonator (i.d. 39 mm) and a 14 mm actively decoupled quadrature surface coil array for 31P signal reception (Rapid Biomedical, Germany). Anatomical scout images were acquired using the 1H channel of the birdcage resonator for both transmit and receive.

Two-dimensional, density-weighted, 31P chemical shift imaging (2D-CSI) was used in short-axis orientation to acquire spectroscopic measurements in vivo (FOV 30 × 30 mm2, 16 × 16 PE steps, 5 mm slice thickness, threefold undersampled, 2600 FIDs, 60° flip angle, cardiac triggered, TR ≈ 250 ms [i.e. two cardiac cycles], total acquisition time ~ 25 min); the resulting spatial resolution was approximately 1.9 × 1.9 × 5.0 mm (voxel volume of 17.6 μL). Prior to Fourier transform, the data were zero-filled to 64 × 64 PE steps to improve the apparent spatial resolution of the images, and a line broadening of 60 Hz was applied to improve the SNR of the resulting spectra.

The data were reconstructed using IDL 8.2 (Harris Geospatial Solutions, USA) and spectra corresponding to voxels placed in the myocardium and blood were fitted in the time domain using in-house software [28]. Correction for myocardial signal contamination from blood, and T1 saturation effects was carried out in Excel 2014 (Microsoft Corporation, USA); T1 values for PCr and ATP in the mouse myocardium at 9.4 T were taken from the literature [7].

Analysis and statistics

Researchers were blinded to experimental groups for all data analysis. A log-rank (Mantel–Cox) test was used to determine whether Kaplan–Meier survival curves were significantly different. Echocardiography data were analysed by two-way repeated-measures ANOVA with Tukey’s multiple comparison test. Haemodynamic, organ weights and biochemistry data were checked for normality using a D’Agostino–Pearson (K2) test and analysed by one-way ANOVA with Sidak’s multiple comparison test if normally distributed, or, by nonparametric Kruskal–Wallis test with Dunn’s correction if not. Four comparisons were predetermined to be made for all analyses: WT-Sham vs. OE-Sham; WT-Sham vs. WT-TAC; OE-Sham vs. OE-TAC; WT-TAC vs. OE-TAC.

The total number of animals entering the study and their subsequent fate are detailed in Supplementary Table 1. The Kaplan–Meier survival curves for the TAC surgery groups (Fig. 1) show a strong trend for improved survival in the OE mice compared to WT (3 deaths from n = 30 OE mice vs. 9 deaths from n = 33 WT, P = 0.08), in particular, within the first 10 days post-surgery. An analysis of the causes of death (Supplementary Table 2) indicates that WT-TAC mice had more incidence of acute and chronic heart failure during that period. Deaths during haemodynamic examination were spontaneous rather than due to surgical error and affected more in the OE group.

Fig. 1

Survival and echocardiographic parameters in sham and transverse aortic constriction (TAC) operated mice. a Kaplan–Meier survival curve for wild-type (WT, n = 33) and Mt-CK overexpressing (OE, n = 30) mice following TAC surgery for the main study and MRS sub-study combined. Sham groups are not shown since there were no procedural deaths. bf Echocardiography parameters derived from 2-D parasternal short-axis views and therefore expressed as areas. The legend and numbers given in (b) apply to all panels: WT-Sham n = 10, OE-Sham n = 12, WT-TAC n = 16; OE-TAC n = 20. There were no significant differences between sham groups for any parameter at any time point. Both TAC groups showed a progressive LV dilation compared to shams during diastole (c) and systole (d) and was significantly more pronounced in the OE mice. e This manifested as a greatly reduced contractile function in both TAC groups compared to sham controls, but to a broadly similar extent. f shows myocardial cross-sectional area as an indicator of LV hypertrophy, which was highly significant in both TAC group irrespective of genotype. Data shown are mean ± standard error with analysis by two-way repeated measures ANOVA with Tukey’s multiple comparison test, *P < 0.05 for OE-Sham versus OE-TAC; #P < 0.05 and $P < 0.001 for both sham groups versus their respective controls

LV remodelling and function

No differences in echocardiographic parameters were evident between WT and Mt-CK-OE animals prior to surgery (week 0) or between sham-operated groups at any time point (Fig. 1). Both TAC groups exhibited overt LV dilatation, contractile dysfunction and LV hypertrophy compared to their sham controls (Fig. 1b–f and representative images in Fig. 2). By 6 weeks post-surgery, the hearts from OE-TAC mice were significantly more dilated than WT-TAC, with a trend towards impaired contractility (Fig. 1e), but with no differences in hypertrophic response (Fig. 1f and confirmed at post-mortem Fig. 3g).

Fig. 2

Representative echocardiograms obtained 6 weeks after transverse aortic constriction (TAC) or sham surgery. a Shows M-mode images from the parasternal short-axis view from all four experimental groups, representing wild-type (WT) and Mt-CK overexpressing mice (OE). b Shows sagittal views through the aortic arch with the aortic root in the upper left of each image. The upper and middle images are from a sham-operated mouse shown with and without colour Doppler for anatomical reference. The lower image illustrates the severe aortic stenosis that was observed in all TAC operated mice

Fig. 3

Left ventricular haemodynamics and organ weights obtained 6 weeks after sham or transverse aortic constriction (TAC). a Heart rate, b LV end-systolic pressure, c LV end-diastolic pressure, d isovolumetric constant of relaxation, tau, as a measure of relaxation, e the rate of pressure rise maximum (dP/dtmax) as a measure of contractility, f dP/dtmax during IV infusion with dobutamine at 16 ng/g BW/min as a measure of contractile reserve. Organ weights were obtained post-mortem and normalised to tibial length for g left ventricle, h right ventricle and i lung weight. Directional changes for all parameters are consistent with severe LV hypertrophy and subsequent development of a heart failure phenotype in TAC animals, which was not affected by genetic modification. Data shown are mean ± standard error for WT-Sham n = 10, OE-Sham n = 12, WT-TAC n = 14; OE-TAC n = 19. Analysis by one-way ANOVA with Sidek’s multiple comparison test, except for data shown in panels b, f, h, and i, which failed the normality test and were analysed by Kruskal–Wallis with Dunn’s correction

A similar pattern was observed for the LV haemodynamic data. There were no significant differences between WT and OE-sham groups, while both TAC groups had significantly impaired LV function compared to their respective sham controls, indicative of chronic heart failure (Fig. 3 and Supplementary Table 3). In both TAC groups, a similar proportion of mice had signs of pulmonary congestion, as evidenced by elevated RV and lung weights at post-mortem (Fig. 3h, i). Mt-CK overexpression did not significantly alter any of these parameters.

Cardiac energetics

Total creatine kinase activity was 37% higher in OE-sham compared to WT-sham hearts (Table 1). As expected, values were lower in both TAC groups, but only in OE hearts was total CK activity maintained above normal WT levels despite the development of heart failure. In OE-sham hearts the relative content of MM-CK isoforms was paradoxically higher, but this was normalised in the OE-TAC hearts, where higher Mt-CK activity made the largest contribution to maintaining total CK activity. No differences in total creatine levels or citrate synthase activity were detected between any groups.

Table 1 LV myocardial enzyme activities and creatine levels

To provide a more sensitive indicator of CK activity, an estimate of relative reaction velocity through Mt-CK was calculated by multiplying by the total creatine concentration (as per [45]). This confirmed that Mt-CK reaction velocity was elevated in OE-sham hearts and was lower in TAC failing hearts, but was nevertheless maintained at supra-normal levels in OE-TAC (Fig. 4).

Fig. 4

Cardiac energetics 6 weeks after sham or transverse aortic constriction (TAC). a Estimate of maximal Mt-CK reaction velocity calculated as product of Mt-CK activity and creatine concentration in ex vivo LV tissue. Mean ± standard error from WT-Sham n = 8, OE-Sham n = 11, WT-TAC n = 16; OE-TAC n = 15, with one-way ANOVA and Sidek’s multiple comparison test *P = 0.03. b Ratio of phosphocreatine (PCr) to γATP peak measured in vivo by 31P-MRS. Mean ± standard error from WT-Sham n = 6, OE-Sham n = 4, WT-TAC n = 6; OE-TAC n = 7, with one-way ANOVA and Dunn's correction, **P = 0.007. cf Representative myocardial spectra from each of the four experimental groups showing peaks for 2,3-Diphosphoglycerate (DPG), PCr and the γ, α, and β phosphoryl groups of ATP alongside corresponding short-axis scout image

The ratio of phosphocreatine to ATP was measured in vivo in a separate cohort of mice and representative scouting image and spectra are shown in Fig. 4. There was no difference in PCr/ATP between sham groups, but the clear trend for lower PCr/ATP in WT-TAC hearts was completely prevented by Mt-CK-OE, such that PCr/ATP was significantly higher in OE-TAC versus WT-TAC hearts (P = 0.007) thereby maintaining normal baseline levels (Fig. 4b).

Here we demonstrate for the first time that overexpression of the mitochondrial isoform of CK preserves normal levels of Mt-CK activity and PCr/ATP ratio in the chronically failing mouse heart. The consequences proved nuanced, since although more Mt-CK-OE mice survived the acute compensatory stage following TAC surgery, they were not subsequently protected from adverse LV remodelling or contractile dysfunction measured at later time points.

There was a clear trend towards improved early survival in the Mt-CK-OE mice (90% vs. 73% for WT), which can be attributed to a higher incidence of heart failure in WT during the first 10 days. This did not quite reach statistical significance, in part, because mortality in the WT group was relatively low (cf. [9]), which inevitably limits the potential effect size and therefore the power of the study to detect it. It is therefore possible and plausible that OE mice are partially protected during the early period of adaptation to acute pressure overload, since workload, and therefore energetic requirements, are high while compensatory adaptations are still developing. This would not be detected by our in vivo assessments at 3 and 6 weeks and therefore further studies of this early response are merited.

We cannot rule out that survival bias may have influenced the later time points. For instance, if mice survived that would otherwise have died during the acute phase, then we would expect them to show more severe indices of heart failure. This could explain why Mt-CK-OE hearts exhibited greater LV dilatation and were more likely to spontaneously stop beating during the stress of haemodynamic assessment.

In all chronic heart failure studies of this type, these is a trade-off between animal welfare and the length of follow-up. It could be argued that the extent of heart failure was not severe enough or sufficiently prolonged, since we did not observe high mortality or large falls in total CK activity or in myocardial creatine levels [Cr]. In this context, was the energetic deficit too mild to demonstrate a rescue? One consideration is the presence of a missense mutation in nicotinamide nucleotide transhydrogenase (Nnt) in the C57BL/6J strain, which has been shown to reduce oxidative stress and ameliorate heart failure induced by TAC [37]. However, this is not a factor here, since our transgenic mice and controls were created from the C57BL/6JOlaHsd substrain, which does not harbour the Nnt mutation [8]. Our previous experience of the TAC model has shown that CK system changes only occur in the most severely affected mice, i.e. those with evidence of pulmonary congestion [22]. Even then we only observed a relatively modest 11% fall in total [Cr], which appears to reflect the lower starting values in this species. In the current study we observe a sizeable subset of animals with elevated lung weights suggesting pulmonary congestion and elevated RV weights indicating prolonged elevation of LV diastolic pressures. Indeed, the values for haemodynamic and echocardiographic parameters are comparable to our previous findings suggesting that we do have an effective heart failure model [22]. It is probably fair to say that ex vivo enzyme activities and substrate pools are the least sensitive measures of energetic status [25].

For this reason, we also estimated maximal reaction velocity by multiplying CK activity by total [Cr], which takes into account changes in both enzyme and substrate, since these are the major determinants of the rate equation [14, 45]. The expected drop in reaction velocity following TAC was observed in both genotypes, but absolute values remained supra-physiological in Mt-CK-OE hearts. In an independent experiment, we also performed in vivo 31P-MRS in these transgenic mice for the first time and showed that PCr/ATP ratio was not altered in the sham animals, but that Mt-CK-OE completely prevented the fall in PCr/ATP commonly observed in the failing heart. The absolute values obtained and the size of PCr/ATP reduction is comparable to other published values for pressure overload in human and mouse [10, 11, 29, 30].

A key question arising from this study is why improved energetics did not translate into improved cardiac function? One possibility is that overexpression of Mt-CK-OE had unknown confounding effects on mitochondria that an improvement in energetics could not overcome. Although we cannot rule this out, it seems unlikely, since we have previously shown that Mt-CK-OE does not affect mitochondrial cell density, citrate synthase activity, or mitochondrial respiration. Metabolomics indicated normal cellular metabolism and expression of closely associated proteins, ANT, VDAC, and BCL-2 were not significantly altered [48]. However, since Mt-CK-OE inhibits mPTP opening, our data raise the possibility that prolonged inhibition might be deleterious in the TAC model.

Similarly, Mt-CK could have increased reactive oxygen species (ROS) or provided a target for oxidative damage that added to the cumulative burden. It is a limitation of our study that we did not quantify the effects of Mt-CK-OE on oxidative stress, however, we have previously found no difference in mitochondrial proton leak and uncoupling, which suggests the major source of cellular ROS is unlikely to be different [48]. Mt-CK has also been found to reduce (rather than increase) ROS formation under stress conditions [31]. Furthermore, Mt-CK protein is very sensitive to oxidative damage and this is reflected in reduced Mt-CK activity [42], yet in the current study, the Mt-CK activity compared to sham was 0.46 IU/mg lower in WT compared to 0.44 IU/mg in Mt-CK-OE hearts. This suggests that mitochondrial exposure to ROS was similar in both heart failure groups.

There is no doubt that PCr/ATP is an important biomarker for the energetic status of the heart. Multiple studies across species and aetiologies have demonstrated that PCr/ATP correlates with measures of cardiac workload, e.g. ejection fraction and wall stress [16, 30, 33, 35]. Improvement in clinical condition is also often tracked by improvement in PCr/ATP [29, 33, 36].

However, PCr/ATP simply reflects relative metabolite pools and is not a specific marker. For example, the fall in this ratio is underestimated in advanced heart failure if both PCr and ATP levels are reduced [25]. PCr/ATP levels are affected by multiple conditions, often before overt contractile dysfunction is evident, e.g. in type 2 diabetes [39], hypertension [16], and obesity [38]. PCr/ATP may also change acutely, e.g. falling in response to increased workload in hearts with pre-existing disease [38].

It should, therefore, not come as a surprise that we occasionally observe a large disconnect between PCr/ATP levels and outcomes. For example, in pressure overload mice (TAC model) a maximal reduction in PCr/ATP was already observed at 3 weeks, but contractile function continued to decline and only correlated with PCr/ATP at 6 weeks [30]. Conversely, in the same TAC model by a different group, contractile dysfunction preceded the fall in PCr/ATP by 11 weeks [1]. Perhaps the most egregious example is in mice null for the GLUT4 transporter, which develop LV hypertrophy and depressed ejection fraction despite myocardial PCr/ATP that is 60% higher [46].

It is also notable that low PCr/ATP does not per se result in contractile dysfunction. Mice fed a high-fat, high-sucrose diet had a 30% reduction in PCr/ATP, but this did not adversely affect function under resting conditions [17]. Similarly, diabetic db/db mice were shown to have a low PCr/ATP early on when cardiac function was normal, but 11 weeks later, function had deteriorated at a time when PCr/ATP improved [1, 19].

It is a strength of our study that 31P-MRS was performed in vivo at physiological workloads, but ideally we would have liked to measure CK flux by saturation transfer, since this is considered a more sensitive indicator than PCr/ATP in chronic heart failure [3, 25]. However, the technical capability in murine heart was not available to us at the time of this study and there are very few groups worldwide that can. Nevertheless, our study shows for the first time that a metabolic intervention effective at preserving PCr/ATP is not sufficient in itself to protect the pressure-overloaded heart from developing CHF. The sole use of PCr/ATP to identify potential new therapeutic agents should therefore be approached with caution.

Our findings are in contrast to transgenic mice overexpressing the muscle isoform of CK in the heart (M-CK), which were shown to have reduced mortality and improved systolic function in the TAC model [9]. This was associated with relative preservation of PCr/ATP levels and CK flux that was maintained at control levels. The reasons for this are not immediately apparent, it is notable that protein expression of Mt-CK was found to be the main determinant of PCr/ATP and of CK flux in a porcine model of pressure overload [49]. This is supported by our own findings and we would therefore expect augmentation of Mt-CK to be a particularly attractive strategy. Perhaps the simplest explanation is one of gene dosing, the M-CK-OE model had ~ 70% increase in total CK activity, whereas it was only 37% higher in our Mt-CK-OE mouse hearts. This was a deliberate strategy on our part, since we were concerned at the potential detrimental effects of expressing too much transgenic protein within a small cellular compartment. However, while we cannot rule out that greater Mt-CK expression would bring benefits, this seems unlikely given that we successfully maintained PCr/ATP and CK reaction velocity at normal levels and this level of Mt-CK overexpression is sufficient to protect against I/R injury [48]. It is possible that the key difference relates to how well ADP is buffered at the myofilaments, since this depends on the activity of cytosolic creatine kinases (predominantly M-CK), which are typically impaired in heart failure and would not be improved by Mt-CK overexpression. ADP levels are not readily detectable by in vivo 31P-MRS, but experiments ex vivo have shown that elevated ADP is enough to cause diastolic dysfunction, particularly in the presence of Ca2+ overload [41, 44]. It may therefore be insufficient to only correct PCr/ATP and there may be synergy in increasing activity of both mitochondrial- and M- CK isoforms together.

Our findings add to the debate on whether impairment of the CK system has a causative role in heart failure progression, which we have previously reviewed in detail [26]. The fact that preventing these changes did not positively influence pathophysiology argues against causation, which is in agreement with our previous studies in several knockout models [5, 20, 23].

In conclusion, overexpression of Mt-CK in the heart successfully maintained key markers of cardiac energetics at or above normal control values. That this was insufficient to improve LV remodelling or function during the development of chronic heart failure shows that normalisation of PCr/ATP and mitochondrial creatine kinase levels are not in themselves curative. Nevertheless, we observed a trend for improved survival during the acute compensatory phase, which suggests a focus for future study.

  1. 1.

    Abdurrachim D, Nabben M, Hoerr V, Kuhlmann MT, Bovenkamp P, Ciapaite J, Geraets IME, Coumans W, Luiken J, Glatz JFC, Schafers M, Nicolay K, Faber C, Hermann S, Prompers JJ (2017) Diabetic db/db mice do not develop heart failure upon pressure overload: a longitudinal in vivo PET, MRI, and MRS study on cardiac metabolic, structural, and functional adaptations. Cardiovasc Res 113:1147–1159.

  2. 2.

    Bittl JA, Weisfeldt ML, Jacobus WE (1985) Creatine kinase of heart mitochondria. The progressive loss of enzyme activity during in vivo ischemia and its correlation to depressed myocardial function. J Biol Chem 260:208–214

  3. 3.

    Bottomley PA, Panjrath GS, Lai S, Hirsch GA, Wu K, Najjar SS, Steinberg A, Gerstenblith G, Weiss RG (2013) Metabolic rates of ATP transfer through creatine kinase (CK Flux) predict clinical heart failure events and death. Sci Transl Med 5:215re213.

  4. 4.

    Cassidy PJ, Schneider JE, Grieve SM, Lygate C, Neubauer S, Clarke K (2004) Assessment of motion gating strategies for mouse magnetic resonance at high magnetic fields. J Magn Reson Imaging 19:229–237.

  5. 5.

    Faller KME, Atzler D, McAndrew DJ, Zervou S, Whittington HJ, Simon JN, Aksentijevic D, Ten Hove M, Choe CU, Isbrandt D, Casadei B, Schneider JE, Neubauer S, Lygate CA (2018) Impaired cardiac contractile function in arginine:glycine amidinotransferase knockout mice devoid of creatine is rescued by homoarginine but not creatine. Cardiovasc Res 114:417–430.

  6. 6.

    Faller KME, Medway DJ, Aksentijevic D, Sebag-Montefiore L, Schneider JE, Lygate CA, Neubauer S (2013) Ribose supplementation alone or with elevated creatine does not preserve high energy nucleotides or cardiac function in the failing mouse heart. PLoS ONE 8:e66461.

  7. 7.

    Flogel U, Jacoby C, Godecke A, Schrader J (2007) In vivo 2D mapping of impaired murine cardiac energetics in NO-induced heart failure. Magn Reson Med 57:50–58.

  8. 8.

    Fontaine DA, Davis DB (2016) Attention to background strain is essential for metabolic research: C57BL/6 and the international knockout mouse consortium. Diabetes 65:25–33.

  9. 9.

    Gupta A, Akki A, Wang Y, Leppo MK, Chacko VP, Foster DB, Caceres V, Shi S, Kirk JA, Su J, Lai S, Paolocci N, Steenbergen C, Gerstenblith G, Weiss RG (2012) Creatine kinase-mediated improvement of function in failing mouse hearts provides causal evidence the failing heart is energy starved. J Clin Invest 122:291–302.

  10. 10.

    Gupta A, Chacko VP, Schar M, Akki A, Weiss RG (2011) Impaired ATP kinetics in failing in vivo mouse heart. Circ Cardiovasc Imaging 4:42–50.

  11. 11.

    Gupta A, Chacko VP, Weiss RG (2009) Abnormal energetics and ATP depletion in pressure-overload mouse hearts: in vivo high-energy phosphate concentration measures by noninvasive magnetic resonance. Am J Physiol-Heart C 297:H59–H64.

  12. 12.

    Heusch G, Libby P, Gersh B, Yellon D, Böhm M, Lopaschuk G, Opie L (2014) Cardiovascular remodelling in coronary artery disease and heart failure. The Lancet 383:1933–1943.

  13. 13.

    Horn M, Remkes H, Stromer H, Dienesch C, Neubauer S (2001) Chronic phosphocreatine depletion by the creatine analogue beta-guanidinopropionate is associated with increased mortality and loss of ATP in rats after myocardial infarction. Circulation 104:1844–1849.

  14. 14.

    Ingwall JS (1998) Energetics of the normal and failing human heart: focus on the creatine kinase reaction. In: Bittar EE, Altschuld RA, Haworth RA (eds) Advances in organ biology. Elsevier, Netherlands, pp 117–141.

  15. 15.

    Ingwall JS, Kramer MF, Fifer MA, Lorell BH, Shemin R, Grossman W, Allen PD (1985) The creatine kinase system in normal and diseased human myocardium. New Engl J Med 313:1050–1054.

  16. 16.

    Lamb HJ, Beyerbacht HP, van der Laarse A, Stoel BC, Doornbos J, van der Wall EE, de Roos A (1999) Diastolic dysfunction in hypertensive heart disease is associated with altered myocardial metabolism. Circulation 99:2261–2267.

  17. 17.

    Luptak I, Sverdlov AL, Panagia M, Qin F, Pimentel DR, Croteau D, Siwik DA, Ingwall JS, Bachschmid MM, Balschi JA, Colucci WS (2018) Decreased ATP production and myocardial contractile reserve in metabolic heart disease. J Mol Cell Cardiol 116:106–114.

  18. 18.

    Lygate C (2006) Surgical models of hypertrophy and heart failure: Myocardial infarction and transverse aortic constriction. Drug Disc Today Dis Models 3:283–290.

  19. 19.

    Lygate CA (2017) Metabolic arithmetic: do two wrongs make a right? Cardiovasc Res 113:1093–1095.

  20. 20.

    Lygate CA, Aksentijevic D, Dawson D, Ten Hove M, Phillips D, de Bono JP, Medway DJ, Sebag-Montefiore L, Hunyor I, Channon KM, Clarke K, Zervou S, Watkins H, Balaban RS, Neubauer S (2013) Living without creatine: unchanged exercise capacity and response to chronic myocardial infarction in creatine-deficient mice. Circ Res 112:945–955.

  21. 21.

    Lygate CA, Bohl S, ten Hove M, Faller KM, Ostrowski PJ, Zervou S, Medway DJ, Aksentijevic D, Sebag-Montefiore L, Wallis J, Clarke K, Watkins H, Schneider JE, Neubauer S (2012) Moderate elevation of intracellular creatine by targeting the creatine transporter protects mice from acute myocardial infarction. Cardiovasc Res 96:466–475.

  22. 22.

    Lygate CA, Fischer A, Sebag-Montefiore L, Wallis J, Ten Hove M, Neubauer S (2007) The creatine kinase energy transport system in the failing mouse heart. J Mol Cell Cardiol 42:1129–1136.

  23. 23.

    Lygate CA, Hunyor I, Medway D, de Bono JP, Dawson D, Wallis J, Sebag-Montefiore L, Neubauer S (2009) Cardiac phenotype of mitochondrial creatine kinase knockout mice is modified on a pure C57BL/6 genetic background. J Mol Cell Cardiol 46:93–99.

  24. 24.

    Lygate CA, Medway DJ, Ostrowski PJ, Aksentijevic D, Sebag-Montefiore L, Hunyor I, Zervou S, Schneider JE, Neubauer S (2012) Chronic creatine kinase deficiency eventually leads to congestive heart failure, but severity is dependent on genetic background, gender and age. Basic Res Cardiol 107:276.

  25. 25.

    Lygate CA, Neubauer S (2014) Metabolic flux as a predictor of heart failure prognosis. Circ Res 114:1228–1230.

  26. 26.

    Lygate CA, Neubauer S (2014) The myocardial creatine kinase system in the normal, ischaemic and failing heart. In: Lopaschuk GD, Dhalla NS (eds) Cardiac energy metabolism in health and disease. Springer-Verlag, New York, pp 155–168.

  27. 27.

    Lygate CA, Schneider JE, Hulbert K, Ten Hove M, Sebag-Montefiore LM, Cassidy PJ, Clarke K, Neubauer S (2006) Serial high resolution 3D-MRI after aortic banding in mice: band internalization is a source of variability in the hypertrophic response. Basic Res Cardiol 101:8–16.

  28. 28.

    Maguire ML, Geethanath S, Lygate CA, Kodibagkar VD, Schneider JE (2015) Compressed sensing to accelerate magnetic resonance spectroscopic imaging: evaluation and application to 23Na-imaging of mouse hearts. J Cardiovasc Magn Reson 17:45.

  29. 29.

    Mahmod M, Francis JM, Pal N, Lewis A, Dass S, De Silva R, Petrou M, Sayeed R, Westaby S, Robson MD, Ashrafian H, Neubauer S, Karamitsos TD (2014) Myocardial perfusion and oxygenation are impaired during stress in severe aortic stenosis and correlate with impaired energetics and subclinical left ventricular dysfunction. J Cardiovasc Magn Reson 16:29.

  30. 30.

    Maslov MY, Chacko VP, Stuber M, Moens AL, Kass DA, Champion HC, Weiss RG (2007) Altered high-energy phosphate metabolism predicts contractile dysfunction and subsequent ventricular remodeling in pressure-overload hypertrophy mice. Am J Physiol Heart Circ Physiol 292:H387–391.

  31. 31.

    Meyer LE, Machado LB, Santiago AP, da-Silva WS, De Felice FG, Holub O, Oliveira MF, Galina A (2006) Mitochondrial creatine kinase activity prevents reactive oxygen species generation: antioxidant role of mitochondrial kinase-dependent ADP re-cycling activity. J Biol Chem 281:37361–37371

  32. 32.

    Nahrendorf M, Spindler M, Hu K, Bauer L, Ritter O, Nordbeck P, Quaschning T, Hiller KH, Wallis J, Ertl G, Bauer WR, Neubauer S (2005) Creatine kinase knockout mice show left ventricular hypertrophy and dilatation, but unaltered remodeling post-myocardial infarction. Cardiovasc Res 65:419–427.

  33. 33.

    Naumova AV, Chacko VP, Ouwerkerk R, Stull L, Marban E, Weiss RG (2006) Xanthine oxidase inhibitors improve energetics and function after infarction in failing mouse hearts. Am J Physiol Heart Circ Physiol 290:H837–843.

  34. 34.

    Neubauer S (2007) The failing heart–an engine out of fuel. New Engl J Med 356:1140–1151.

  35. 35.

    Neubauer S, Horn M, Pabst T, Gödde M, Lübke D, Jilling B, Hahn D, Ertl G (1995) Contributions of 31P-magnetic resonance spectroscopy to the understanding of dilated heart muscle disease. Eur Heart J 16:115–118.

  36. 36.

    Neubauer S, Krahe T, Schindler R, Horn M, Hillenbrand H, Entzeroth C, Mader H, Kromer EP, Riegger GA, Lackner K, Ertl G (1992) 31P magnetic resonance spectroscopy in dilated cardiomyopathy and coronary artery disease. Altered cardiac high-energy phosphate metabolism in heart failure. Circulation 86:1810–1818.

  37. 37.

    Nickel Alexander G, von Hardenberg A, Hohl M, Löffler RJ, Kohlhaas M, Becker J, Reil J-C, Kazakov A, Bonnekoh J, Stadelmaier M, Puhl S-L, Wagner M, Bogeski I, Cortassa S, Kappl R, Pasieka B, Lafontaine M, Lancaster C, Roy D, Blacker TS, Hall AR, Duchen MR, Kästner L, Lipp P, Zeller T, Müller C, Knopp A, Laufs U, Böhm M, Hoth M, Maack C (2015) Reversal of mitochondrial transhydrogenase causes oxidative stress in heart failure. Cell Metab 22:472–484.

  38. 38.

    Rider OJ, Francis JM, Ali MK, Holloway C, Pegg T, Robson MD, Tyler D, Byrne J, Clarke K, Neubauer S (2012) Effects of catecholamine stress on diastolic function and myocardial energetics in obesity/clinical perspective. Circulation 125:1511–1519.

  39. 39.

    Scheuermann-Freestone M, Madsen PL, Manners D, Blamire AM, Buckingham RE, Styles P, Radda GK, Neubauer S, Clarke K (2003) Abnormal cardiac and skeletal muscle energy metabolism in patients with type 2 diabetes. Circulation 107:3040–3046.

  40. 40.

    Schlattner U, Tokarska-Schlattner M, Wallimann T (2006) Mitochondrial creatine kinase in human health and disease. Biochim Biophys Acta 1762:164–180.

  41. 41.

    Sequeira V, Najafi A, McConnell M, Fowler ED, Bollen IAE, Wüst RCI, dos Remedios C, Helmes M, White E, Stienen GJM, Tardiff J, Kuster DWD, van der Velden J (2015) Synergistic role of ADP and Ca2+ in diastolic myocardial stiffness. J Physiol 593:3899–3916.

  42. 42.

    Soboll S, Brdiczka D, Jahnke D, Schmidt A, Schlattner U, Wendt S, Wyss M, Wallimann T (1999) Octamer-dimer transitions of mitochondrial creatine kinase in heart disease. J Mol Cell Cardiol 31:857–866.

  43. 43.

    Teerlink T, Hennekes M, Bussemaker J, Groeneveld J (1993) Simultaneous determination of creatine compounds and adenine nucleotides in myocardial tissue by high-performance liquid chromatography. Anal Biochem 214:278–283.

  44. 44.

    Tian R, Christe ME, Spindler M, Hopkins JC, Halow JM, Camacho SA, Ingwall JS (1997) Role of MgADP in the development of diastolic dysfunction in the intact beating rat heart. J Clin Invest 99:745–751.

  45. 45.

    Tian R, Nascimben L, Kaddurah-Daouk R, Ingwall JS (1996) Depletion of energy reserve via the creatine kinase reaction during the evolution of heart failure in cardiomyopathic hamsters. J Mol Cell Cardiol 28:755–765.

  46. 46.

    Weiss RG, Chatham JC, Georgakopolous D, Charron MJ, Wallimann T, Kay L, Walzel B, Wang Y, Kass DA, Gerstenblith G, Chacko VP (2002) An increase in the myocardial PCr/ATP ratio in GLUT4 null mice. FASEB J 16:613–615.

  47. 47.

    Wendt S, Schlattner U, Wallimann T (2003) Differential effects of peroxynitrite on human mitochondrial creatine kinase isoenzymes: inactivation, octamer destabilization, and identification of involved residues. J Biol Chem 278:1125–1130.

  48. 48.

    Whittington HJ, Ostrowski PJ, McAndrew DJ, Cao F, Shaw A, Eykyn TR, Lake HA, Tyler J, Schneider JE, Neubauer S, Zervou S, Lygate CA (2018) Over-expression of mitochondrial creatine kinase in the murine heart improves functional recovery and protects against injury following ischaemia–reperfusion. Cardiovasc Res 114:858–869.

  49. 49.

    Ye Y, Gong G, Ochiai K, Liu J, Zhang J (2001) High-energy phosphate metabolism and creatine kinase in failing hearts: a new porcine model. Circulation 103:1570–1576.

  50. 50.

    Zervou S, Whittington HJ, Ostrowski PJ, Cao F, Tyler J, Lake HA, Neubauer S, Lygate CA (2017) Increasing creatine kinase activity protects against hypoxia/reoxygenation injury but not against anthracycline toxicity in vitro. PLoS ONE 12:e0182994.

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This study was funded by British Heart Foundation Programme Grants (RG/13/8/30266, RG/18/12/34040); a Rhodes Scholarship to FC; and core support from the Oxford British Heart Foundation Centre of Research Excellence (RE/13/1/30181), and Wellcome Trust Core Award (Grant Number 203141/Z/16/Z).

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Cao, F., Maguire, M.L., McAndrew, D.J. et al. Overexpression of mitochondrial creatine kinase preserves cardiac energetics without ameliorating murine chronic heart failure. Basic Res Cardiol 115, 12 (2020) doi:10.1007/s00395-020-0777-3

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  • Cardiac energetics
  • Metabolism
  • Creatine kinase
  • Heart failure
  • Transgenic


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Pro PayPal E-Commerce contains the most comprehensive collection of information on PayPal technologies. It takes the approach of PayPal as a digital money platform, and shows how its a dynamic service that offers far more than just payment processing.

With its breadth of technologies and APIs, the PayPal platform is a basis for development and innovation for an unlimited number of possibilities. It offers a wide range of payment technologies, but its not always easy to decipher which technology is the best choice for a web site. This book gets under the hood to show you how the different technologies work, how to choose the right solution, and how to implement the solutioncomplete with real-world PayPal success stories.

Youll learn how to integrate PayPal directly into web sites to make use of its payment technologies. This allows you, no matter what language you program in, to build shopping carts or similar channel products with PayPal as a payment option. You can also use this book to learn about the basics of e-commerce, where PayPal fits in, and how you can meet your own e-commerce needs. This book covers

  • How PayPal works
  • Using the PayPal API
  • Website Payments Standard
  • Website Payments Pro
  • Instant Payment Notification
  • Payment Data Transfer
  • Encrypted Website Payments
  • Administration
  • Reporting
  • Fraud protection
  • Payflow Gateway

E-Commerce PayPal Web Web Services development language

Bibliographic information


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About the Film

Linotype: The Film is a feature-length documentary centered around the Linotype type casting machine. Called the "Eighth Wonder of the World" by Thomas Edison, it revolutionized printing and society. The film tells the charming and emotional story of the people connected to the Linotype and how it impacted the world.

The Linotype (pronounced "line-o-type") completely transformed the communication of information similarly to how the internet is now changing communication again. Although these machines were revolutionary, technology began to supersede the Linotype and they were scrapped and melted-down by the thousands. Today, very few machines are still in existence.

About Exclamation

The highly-skilled operators of the Linotype are in a battle against time. If their skills are not passed along to a new generation of operators, the machine will die completely. There is a small group of former operators that want to save the Linotype from the scrap yard, but some see this as a fruitless endeavor.

What place does the Linotype have in the age of new technology? Should the machine be shoved into a museum and left to rust? Why should anyone care about typography or the technology of communication? The film seeks to answer these questions.

Production and Release

Production started in August of 2010 and the world premiere was in New York City at the SVA Theatre on February 3, 2012. The film was released digitally and on DVD/Blu-ray on October 16, 2012. You can purchase the film here.

About the Filmmakers

Doug Wilson – Director & Producer

Doug comes to the film from a background of graphic design and letterpress printing. Born and raised in the Midwest, he has travel in his blood and has visited five continents.

He has a BFA in Graphic Design and Art History. In 2008, he spent a summer as an artist in residence at l'Association pour le Patrimoine Industriel in Geneva, Switzerland. He also has worked at an advertising agency and taught typography as an adjunct professor.

When not editing the film, he enjoys the great outdoors with his wife, Allison.

Fun Fact: Doug loves olive oil, but really can't stand the taste of olives.

Brandon Goodwin – Director of Photography and Editor

Brandon bought a video camera and an Apple Powerbook his senior year of high school (the same year his green 1992 Camaro was stolen on his way to homecoming). He has been working as a freelance producer, director, videographer, and writer ever since.

He runs Goodwin Films, a video production company in Springfield, Missouri that has produced videos for Warner Bros. Records, Virgin Records, and PepsiCo.

He believes in the power of a good story and that Peanut Butter Captain Crunch is the greatest cereal ever created.

Fun Fact: Brandon secretly wants to be Anderson Cooper.

Jess Heugel – Audio & Sound Design

When Jess was 15 he moved with his family to Kenya and spent his high-school years amazed by the beauty, sorrow, and humor of East Africa. In Kenya, Jess started shooting pictures in an attempt to process the world around him.

After completing a degree in journalism, Jess spent a few years as a newspaper photojournalist. Since 2008, he has been working as a freelance media producer.

Jess fills his time playing music, writing, and university teaching. He keeps busy, but is always ready to call it a day and go home to his wife, Kelly.

Fun Fact: Jess flew in an airplane with Doug at the controls. He was scared.