The vanishing gender?

The literature data indicating a significant impairment of the basic parameters of male reproductive function in the last decades are analyzed and summarized. This impairment is expressed in the reduction of spermatogenic activity, increased incidence of genital malformations and testicular tumors. The listed changes are reviewed in comparative aspect and include examples of some species of wild animals. The data on the factors responsible for occurrence of pathological changes in male reproductive system are analyzed.     

Relationship between various clinical parameters and duration and variability of Q-T and R-R intervals in ECG (an epidemiological population study)

AIM: To study the relationship between clinical values of a standard epidemiological study of a male population and the length and variability of Q-T and R-R intervals. MATERIAL AND METHODS: A representative sampling from a male population (2184 subjects aged 25-64 years) in Novosibirsk was examined using standard epidemiological methods. Later 251 men were excluded from the study because of impossibility of correct analysis of ECG. The length and dispersion of Q-T interval and time parameters of variability of R-R interval were evaluated. RESULTS: The size and variability of Q-T and R-R intervals are associated with age and AP irrespective of other clinical parameters of a simultaneous epidemiological study. The length of R-R interval is independently related to body weight index, tobacco smoking, and plasma triglyceride level. R-R variability parameters are associated with coronary disease irrespective of the risk factors. CONCLUSION: Scanning studies with complex analysis of Q-T and R-R interval duration and variability effectively detect subjects at a high risk of arrhythmias and fatal events.     

Selective Effects of an NMDA Glutamate Receptor Antagonist on the Sensory Input from Chemoreceptors in the Snail's Head during Acquisition of Nociceptive Sensitization

Experiments on semi-intact preparations from common snails were used to study the characteristics of the actions of MK-801, an antagonist of NMDA glutamate receptors, on the plasticity of various sensory inputs to defensive behavior command neurons LPl1 and RPl1 during acquisition of nociceptive sensitization. Application of sensitizing stimuli to the head or foot of control snails led to depression of neuron responses to tactile and chemical sensory stimulation during the short-term stage and marked facilitation of these responses during the long-term stage of sensitization. Application of sensitizing stimuli to the snail's head during administration of MK-801 led to marked depression of responses to chemical stimulation of the head in both the short-term and long-term stages of sensitization. In addition, blockade of NMDA receptors during application of sensitizing stimuli to the foot or head had no effect on changes in neuron responses elicited by chemical stimulation of the snail's foot and by tactile stimulation of the foot or head. It is suggested that NMDA-like glutamate receptors are selectively involved in the mechanism of induction of plasticity of synaptic inputs to command neurons LPl1 and RPl1, excited by chemical sensory stimulation of the head – a skin receptor zone specific for these neurons.     

Ecological factors that influence the dynamics of the total store of Daursk suslik fleas in the Transbaikal natural focus of plague

Based on 20-year (1967-1987) studies of the dynamic of the total store of the imago of Daursk souslik fleas in the Transbaikal natural focus of plague and of changes in the abiotic and biotic parameters of the environment, the authors have identified factors that statistically significantly influence the study processes. The analysis was made by the nonlinear multiple regression test. One to three predictors of flea abundance have been detected for each month from May to April inclusive.     

Search for substances with antioxidant and antiamnestic activities among 2-substituted 4-(3H)-quinazolones

We have synthesised some of 2-substituted 4-(3H)-quinazolones by the reaction with benzaldehyde and cinnamic aldehyde and their derivatives. It is shown that the intensity of the reaction depends on electrophilic properties of carbonyl compounds and steric factors. The elemental analysis, ultraviolet (UV), infrared (IR) and nuclear magnetic resonance (NMR) spectroscopy confirmed the structure of synthesised compounds, their individuality being checked by thin-layer chromatography. The results of biological experiments show that the synthesised 2-substituted 4-(3H)-quinazolones have an expressed antioxidant and antiamnestic activity and are prospective for further research of their nootropic activity.     

Properties of derived cochlear action potentials in forward tonal masking in guinea pigs

Chronic experiments on guinea pigs were used to study the characteristics of cochlear nerve action potentials and the derived potential in conditions of forward masking. The auditory nerve action potential was recorded from the round window of the cochlea. The derived potential was obtained by subtracting the action potential recorded with masking from the response obtained in silence. These studies showed that the derived potential showed higher sensitivity to masking than the traditional measure of masking, i.e., the decrement in the amplitude of the auditory nerve action potential. The derived potential reflects not only changes in the action potential during masking, but also changes in its shape. Differences between the derived potential and the action potential decrement provide evidence that the amplitude and time changes in the derived potential provide more complete information on the nature of activity in the auditory fibers. Translated from Rossiiskii Fiziologicheskii Zhurnal imeni I. M. Sechenova, Vol. 85, No. 6, pp. 751–766, June, 1999.