The evaluation and prognosis of the psychophysiological status of a human operator

In experiments on 56 healthy subjects (18-20 years old) the quality of their activity was determined during compensatory watching the mark at complicating regimes of work. Depending on the difficulty of the task five groups of subjects were singled out with optimum working capacity in one of four working conditions: normal, ordinary and strenuous work, model of stress situation. It is established that the change of the number of significant correlative connections between main parameters of psychophysiological state of man-operator reflects the condition of his functional systems. On the basis of computation of total range of organization values of both R-R intervals of the ECG and duration of expiration, the success of the man-operator work in complex conditions of activity is predicted.     

Energy metabolism and lipid peroxidation of human erythrocytes as a function of increased oxidative stress.

To study the influence of oxidative stress on energy metabolism and lipid peroxidation in erythrocytes, cells were incubated with increasing concentrations (0.5-10 mM) of hydrogen peroxide for 1 h at 37 degrees C and the main substances of energy metabolism (ATP, AMP, GTP and IMP) and one index of lipid peroxidation (malondialdehyde) were determined by HPLC on cell extracts. Using the same incubation conditions, the activity of AMP-deaminase was also determined. Under nonhaemolysing conditions (at up to 4 mM H2O2), oxidative stress produced, starting from 1 mM H2O2, progressive ATP depletion and a net decrease in the intracellular sum of adenine nucleotides (ATP + ADP + AMP), which were not paralleled by AMP formation. Concomitantly, the IMP level increased by up to 20-fold with respect to the value determined in control erythrocytes, when cells were challenged with the highest nonhaemolysing H2O2 concentration (4 mM). Efflux of inosine, hypoxanthine, xanthine and uric acid towards the extracellular medium was observed. The metabolic imbalance of erythrocytes following oxidative stress was due to a dramatic and unexpected activation of AMP-deaminase (a twofold increase of activity with respect to controls) that was already evident at the lowest dose of H2O2 used; this enzymatic activity increased with increasing H2O2 in the medium, and reached its maximum at 4 mM H2O2-treated erythrocytes (10-fold higher activity than controls). Generation of malondialdehyde was strictly related to the dose of H2O2, being detectable at the lowest H2O2 concentration and increasing without appreciable haemolysis up to 4 mM H2O2. Besides demonstrating a close relationship between lipid peroxidation and haemolysis, these data suggest that glycolytic enzymes are moderately affected by oxygen radical action and strongly indicate, in the change of AMP-deaminase activity, a highly sensitive enzymatic site responsible for a profound modification of erythrocyte energy metabolism during oxidative stress.     

D-glucosamine propanedithioacetal, an efficient chiral auxiliary in beta-lactam chemistry.

The synthesis of some monocyclic beta-lactams (monobactams) by the Staudinger reaction using D-glucosamine propanedithioacetal as chiral auxiliary is reported. The influence of several radicals at C3, C4, and C1' (sugar moiety) as well as other structural aspects are considered in relation to the antielastase activity.     

Population structure of the intertidal copepod Tigriopus californicus as revealed by field manipulation of allele frequencies

Summary Allele frequencies in natural T. californicus populations were perturbed by introduction of copepods from neighboring differentiated populations. In five experiments, the Gpt ^F allele was introduced into single recipient pools at a frequency of approximately 20%. In each case, the introduced allele declined to low frequencies (<3%) in less than one month, apparently due to dilution by residents of other pools on the same outcrop. In a larger scale experiment, the Pgi ^F was introduced into four pools on a single small rock outcrop; all pools on the outcrop were subsequently monitored. While the allele frequency fell from approximately 40% to 10% during the first six weeks after the transplant, no further change in frequency was observed for the duration of the experiment (16 months). Within six weeks some spread of the allele to non-recipient pools on the same outcrop was observed; by eight months, allele frequencies in all pools on the outcrop were similar. Hence, despite the extensive turnover of subpopulations as single pools evaporate or are washed out, genetic homogeneity and stability of entire outcrops are maintained via extensive inter-pool gene flow; this contrasts sharply with the highly restricted levels of inter-outcrop gene flow.