Interference by cellular phones with permanent implanted pacemakers: an update.

AIMS: The aim of this study was to test pacemakers with feedthru filters for interference with a digital cellular telephone. METHODS: The study comprised 100 patients having their first pacemaker implantation between January 2001 and May 2003. A GSM-standard cellular phone was tested in the standby, dialing and operating mode against 23 single-chamber and 77 dual-chamber pacemakers. Continuous surface electrocardiograms, intracardiac electrograms, and marker channels were recorded when calls were made by a land phone to the cellular phone. RESULTS: In 2 patients we observed pacing inhibition with the cellular phone positioned directly above the pacemaker pocket. The unipolar and bipolar ventricular sensitivity setting was 0.25 mV in one dual-chamber pacemaker, and when we changed the sensitivity to 0.50 mV and higher no interference could be detected. The second inhibition occurred in a single-chamber pacemaker with unipolar and bipolar ventricular sensitivity setting of 0.5 mV, where a sensitivity change to 1.0 mV eliminated the interference. CONCLUSION: Anticipating a correct setting of ventricular sensitivity, currently available pacemakers equipped with feedthru filters do not show any interference with cellular phones. Since interference was only observed with sensitivity settings below 0.50 mV, we recommend that permanent programming of ventricular sensitivity should be set at 2.0 mV and higher.

Synthesis and properties of the first all-aza analogue of a biologically active peptide.

The synthesis of the first all-aza-amino acid analogue (2) of a peptidic renin inhibitor is described. The X-ray structural analysis and molecular modelling investigations of this novel compound reveal interesting conformational features which have a significant impact on its biological activity. In addition, insight into conformational features of azapeptides in general in comparison with the corresponding purely peptidic compounds is given.

Anaerobic Degradation of Carrageenan from the Red Macroalga Eucheuma cottonii.

Anaerobic degradation of the sulfated polysaccharide carrageenan was investigated by batch digestion of the red macroalga Eucheuma cottonii. During a 10-week incubation, ca. 60% of the starting E. cottonii biomass was fermented to CO(2), methane, and volatile fatty acids (predominantly acetate). Carrageenan degradation paralleled the loss of total biomass, suggesting no preferential degradation or preservation. After 10 weeks of incubation, the carrageenan content of the remaining biomass was 51%, as opposed to 61% of the original E. cottonii biomass. Carrageenan recovered after 10 weeks of digestion had a lower average molecular weight (319,000 versus 510,000) and formed solutions with considerably lower viscosities than did intact carrageenan. The percent C and percent N content of the particulate material in the digestors increased over time, probably as a result of microbial growth. In contrast, the percent S content decreased continuously; the loss of sulfur was most likely a result of the hydrolysis of carrageenan. Results from this study indicate that it is not economically viable to process E. cottonii simultaneously for hydrocolloids and methane.