Zinc feeding and fertility of male rats

Supplementation of the diet of adult male rats with 4,000 ppm zinc as ZnSO4 for 30 to 32 days increased the zinc content in the testis and sperm by 25 and 18 per cent respectively, but did not change the same in accessory reproductive tissues, e.g. epididymis, seminal vesicle and prostate. The incidence of conception from mating between normal females and zinc fed males was lower as compared to mating between normal females and control males. This observation indicated reduced fertility of the males resulting from additional zinc ingestion. Motility of the sperm collected from the epididymis (tail) of the zinc treated rats was found to be inhibited. It has been suggested that excess zinc in the sperm was responsible for their poor motility and hence a reduced fertilising capacity.     

Production of elastase and other exoproducts by environmental isolates of Pseudomonas aeruginosa.

Pseudomonas aeruginosa isolates from environmental sources and bacteremic patients were compared for their levels of elastolytic activity. No significant differences were found. The incidence of production of toxin A, phospholipase C, alkaline protease, and elastase among the environmental strains was also as high as that previously reported for clinical isolates.     

An unusual case of cutaneous listeriosis.

Listeria monocytogenes was identified as the etiological agent in the cutaneous and febrile illness of a 64-year-old male who acquired the organism as a result of contact with the genital tract of a cow while assisting in the delivery of a stillborn calf.     

Methodological problems in the study of classical aversive conditioning of adrenocortical responses

The present studies were conducted to demonstrate classical aversive conditioning of a corticosterone stress response in male rats. In the first experiment animals exposed to an odor which had previously preceded tube restraint stress had significantly higher plasma corticosterone levels than animals which were probed with a novel odor, or animals in which stress was followed, rather than preceded, by the odor. Careful consideration of corticosterone responses obtained on different days during training made it impossible to conclude unequivocally that learning had occurred. A second experiment was designed specifically to deal with the problems raised by the first, but we were again unable to show rigorously that learning had taken place. However, with data and paradigms comparable to our own, other researchers have prematurely concluded that aversive visceral conditioning can occur. It is suggested that the methodological considerations raised in the present studies could also be important for interpreting other experiments. Given the classical importance ascribed to learning components in many psychosomatic pathologies, future experiments are necessary to determine if stress responses can be classically conditioned, but they must be more rigorously designed than in the past.     

Structure of receptive fields of visually sensitive neurons of the cat hippocampus

Structure of receptive fields of visually sensitive neurons in areas CA1 and CA3 of the dorsal hippocampus was investigated in alert cats with the brain-stem pretrigeminal section. The receptive field (RF) structure of 76 hippocampal neurons was analyzed by methods of scanning the RF by moving stimuli and mapping all their surface by a stationary flashing spot. According to presented data the neurons were classified into three groups: neurons with homogeneous structure of the RF (54%), with nonhomogeneous (28%) and neurons more sensitive to stimulus motion (18%) than to a stationary flashing light. Experiments have shown that responses of hippocampal neurons are highly specific ones. Thus, 9% of neurons with the nonhomogeneous RF structure have shown specific responses to variation of the contrast and contours of moving stimuli. The presented results show that hippocampal visually driven neurons have well developed mechanism for processing visual sensory information and apparently this quality ensures participation of the limbic system in visually controlled behavior of the animal.     

Paranoid and aggressive behavior in two obsessive-compulsive adolescents treated with clomipramine.

Obsessive-compulsive disorder is increasingly recognized in patients of different age groups. Serotonergic agents, such as clomipramine, have been recently found to be useful in the management of this condition. However, unexpected side effects, such as dysphoria, aggressiveness, and paranoid ideation, may occur with therapeutic doses of this compound, as evidenced in the cases of two male adolescents presented here. Possible pathogenetic factors, involving serotonin and serotonin-receptor abnormalities are discussed. Management of these side effects is based on adequate dose reduction and monitorization.     

In vivo effect of prothymosin-alpha 1 on humoral and cell-mediated immune responses in the young rat.

There is a large body of evidence for the role of thymosin peptides in immunogenesis and immunity. In this paper we report on the influence of prothymosin alpha 1 (ProT-alpha 1), a hormone-like peptide derived from the calf thymus, on humoral and cellular immune reactions in the rat. Young adults received intraperitoneal injections of ProT-alpha 1 in the periods before and after immunization with cellular and soluble antigens. ProT-alpha-treatment produced a dose-dependent increase of both humoral and cell-mediated immune responses. The thymus weight increased but not that of spleen. Treatment of nonimmunized rats with this polypeptide significantly elevated the number of CD4+ and decreased the number of CD8+ cells in the peripheral blood. The results suggest a potent immunostimulatory activity of ProT-alpha 1 and imply direct action of this polypeptide on T lymphocytes.