Subsite mapping of enzymes. Double inhibition studies

Our earlier subsite mapping studies led us to believe that ground state distortion occurred when a glucopyranoside ring filled the site which held the substrate monomer unit transferred to water during hydrolysis. We tested this hypothesis by performing double inhibitor studies on two amylases (EC 3.2.1.1) of bacterial origin. A general theory for multiple inhibition of this type is developed and applied to these two enzymes. Our data are consistent with the hypothesis that ground state strain occurs when substrates are bound to carbohydrates. An explanation is offered to account for the fact that monomers give strictly competitive inhibition patterns. The subsite model predicts that noncompetitive or mixed inhibition patterns can occur.     

Influence of long-term low direct current on rat ischiadic nerves

The effects of a low direct current on peripheral nerves and electrodes on the ischiadic nerve were investigated, and a constant direct current was applied for various time periods. Afterwards clinicophysiological tests and histological evaluations were performed. The muscles of 55 rats could be stimulated by external stimulation during the follow-up examinations, but 90% of all animals showed microscopically visible nerve tissue alterations which might have been caused by mechanical rather than electrolytic factors.     

Drastic increase in the prevalence of Echinococcus multilocularis in foxes (Vulpes vulpes) in southern Bavaria, Germany

A survey on the prevalence of Echinococcus multilocularis in foxes was conducted in the administrative district of Starnberg (federal state of Bavaria, Germany) and some adjacent municipalities from October 2002 to March 2003. The background to the study was the scarcity of recent data for Bavaria, where, in contrast to neighbouring regions, a general increase in the prevalence of the parasite has not yet been demonstrated. To estimate the current infection rate, a total of 268 shot foxes were examined using the intestinal scraping technique, resulting in an overall prevalence of 51%. This was compared with retrospective data collected during the period from 1989 to 2001. For the corresponding area and season, the retrospective prevalence was estimated at 32%, based on 222 shot foxes. The prevalence and its temporal development differ considerably on small spatial scales. The most conspicuous change has taken place in the western part of the study area, where a previous prevalence of 35% has increased to 80% in 2002/2003.     

Models for deploymerizing enzymes: criteria for discrimination of models

Several models for the action of alpha amylase have been proposed to account for the nonrandom distribution of oligosaccharides in the amylase digests of polysaccharides. The preferred-attack model attempts to account for the nonrandom distribution by assuming that the probability for bond cleavage depends upon the position of the bond in the chain. The repetitive, or multiple-attack, model suggests that the nonrandom distribution of oligosaccharides arises because an amylase can form a cage-like complex with a substrate and attack it several times during a single encounter. The multiple-enzyme or dual-site model suggests that the nonrandom yield of oligosaccharides arises from the combined action of exo- and endo-enzymes. The effects of pH, inhibitors, and substrate chain-length on enzyme action have been studied in several laboratories to determine which of the three action-patterns best describes the action of alpha amylase. The influence of these variables on product distributions or enzyme action-patterns are mathematically modeled in the Appendix. The experimental data on porcine-pancreatic alpha amylase are discussed in the light of the derivations.     

New evidence for the polycentric evolution of Homo sapiens

The present author published, in 1962 and 1964, a hypothesis according to which modern-type man came into existence independently, in that least three separate geographic centres, during the Upper Pleistocene. New fossil finds corroborate two statements made in previously published papers: (a) Djebel Sahaba shows that recent negroids are modified ancient europoids, and (b) the Palaeosiberian affinities of Wadi-el-Amud indicate the early separation of mongoloid race ancestors at the Palaeanthropic phase.