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1. Ischaemia was applied for 30 min to the liver of Wistar rats and of gsd/gsd rats, which have a genetic deficiency of phosphorylase kinase. The rate of glycogenolysis corresponded closely to the concentration of phosphorylase a. The loss of glycogen from Wistar livers was accounted for by the intrahepatic increase in glucose plus lactate. Further, the accumulation of oligosaccharides was negligible in the gsd/gsd liver. 2. Isolated hepatocytes from Wistar and gsd/gsd rats were incubated for 40 min in the presence of either KCN or glucagon. Again, the production of glucose plus lactate was strictly dependent on the presence of phosphorylase a. However, the catalytic efficiency of phosphorylase a was about 2-fold higher in the presence of KCN. 3. We conclude that the hepatic glycogenolysis induced by anoxia and by KCN is solely mediated by phosphorylase a. The higher catalytic activity of phosphorylase a under these circumstances could be due to an increased concentration of the substrate Pi.

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In this paper, a 6-bit CMOS analog-to-digital converter (An>) with a maximum acquisition speed of 1 GHz is presented. The problem of meta-stability has got special attention in this design, since this problem degrades the Spurious-Free Dynamic Range (SFDR) at high sampling frequencies. Measured SNDR (Signal to noise plus distortion) is over 30 dB at SOOMHz clock and f,N = 141 kHz. The measured SFDR for input frequencies up to 250 MHz is over 3OdB. The chip has been processed in a standard 0.35pm CMOS technology with double poly and occupies an active area of 0.8 mm2. IntroductionHigh-speed A/D converters used in automated test equipment, oscilloscopes and in digital data reading (e.g. hard disk drives and DVD) require very high sampling speeds, whereas resolutions as low as 6 bit are sufficient. Also, the enhanced capability of digital signal processing (DSP) circuits pushes the design of A/D converters towards ever-increasing sampling speeds. Not only the sampling speed is going up, also the maximum input frequency which has to be converted increases. Therefore, bandwidth-, distortion-and error rate-specifications are of utmost importance. Error rate is an aspect in the design of high-speed A/D converters which is often overlooked or underestimated. When the error rate is extremely high, the digitized waveform appears to disintegrate and the signalto-noise ratio (SNR) deteriorates rapidly. Since the error rate increases exponentially with the acquisition frequency, the metastability errors might increase by orders of magnitude for very high speed converters. Therefore, to achieve a good performance at high frequencies the problem of metastability must be tackled. Flash-type architectures are typically the simplest and fastest structures that can be used to implement these very