Effects of unilateral cochlea removal on anteroventral cochlear nucleus neurons in developing gerbils

Afferent regulation of neurons in the cochlear nucleus as a function of age was investigated at the light microscope level. Unilateral cochlea removal was performed on Mongolian gerbils of three age groups: 1, 8, and 20 weeks postnatal. Animals survived for either 2 days or 2 weeks. An additional group of neonatally operated animals had a prolonged survival of 9 weeks. The number of neurons in anteroventral cochlear nucleus (AVCN) was counted, and cross-sectional area measurements of large spherical cells in AVCN were made. In animals 1 week old at the time of surgery, there was a 35% reduction in neuron number in AVCN after 2 days, a 58% reduction after 2 weeks, and a 59% reduction 9 weeks after inner ear destruction. However, in animals 20 weeks old at the time of surgery, there was no cell loss in AVCN either 2 days or 2 weeks after surgery. Animals in each age group showed a reduction in cross-sectional area of large spherical cells in AVCN after cochlea ablation. The gerbils that underwent cochlea removal at 8 and 20 weeks showed an average decrease of 14-18%. This effect was seen as early as 2 days after cochlea removal. Animals that underwent cochlea removal at 1 week exhibited the greatest change; a 25% decrease at 2 days progressed to 38% at 2 weeks following cochlea removal. No appreciable further changes were seen at 9 weeks after neonatal cochlea removal. The results indicate greater susceptibility of 1-week-old gerbil cochlear nucleus neurons to peripheral loss than found in older animals.(ABSTRACT TRUNCATED AT 250 WORDS)     

Prevalence of anticardiolipin antibodies in the elderly British population

In a cross-sectional study of 100 healthy elderly individuals, anticardiolipin antibodies (aCL) were measured using an ELISA technique. aCL were not detected in the majority of subjects (63%), and in the remaining 37% titres were within the laboratory reference range (mean +5 standard deviations) previously determined for adults of all ages. In contrast, significant titres of IgM rheumatoid factor were found in 10%, antimitochondrial antibody in 13%, antinuclear factor in 5%, anti-smooth muscle antibody in 18%, antiparietal cell antibody in 10%, and antireticulin antibody in 1%. Antibodies to single or double-stranded DNA were not detected in any subject. We conclude that, although other auto-antibodies may be present in the healthy aging population in Britain, abnormally elevated levels of aCL antibody do not occur, and when present may be an indicator of autoimmune-mediated pathology.     

Toxicity of tomato red, a popular food dye blend on male albino mice

Colour in food is an integral part of our culture and is also indispensable to the modern day consumer. During the past several decades, the technology of food processing has changed dramatically and the growth in the use of synthetic food colours as an individual dye or in the form of blends has increased enormously. In the present investigation, an attempt has been made to evaluate the toxic effects of a commonly used dye blend, tomato red on male Swiss albino mice. The mice were treated orally with 2 and 6g/kg body weight/day for 42 days. The present study revealed an increase in the body weight and liver weight. However, a decrease was recorded in the weights of kidneys and testes. Histopathological study revealed severe degenerative changes in the liver, kidney and testes. In conclusion, the use of the dye blend in various food items has adverse effect on the vital organs.     

Mechanosensory projections to cerebral cortex of sheep

This study mapped the mechanosensory projections to cerebral cortex of sheep, to complete earlier partial maps and to relate cortical projections to the organization previously determined in ventrobasal thalamus. Tungsten microelectrodes were used to explore thoroughly the walls and depths of cortical sulci as well as the previously studied gyral crowns, for regions responsive to mechanical stimulation of peripheral receptors, in sheep anesthetized with Dialurethane or nitrous oxide with either halothane or methoxyflurane. Earlier findings of a large projection from the ipsilateral mouth, lips and nose were confirmed. In addition, a small representation of the contralateral body and limbs was found which corresponds in most respects to the “second” sensory area (SII) of other mammals. In the primary (SI) sensory cortex, representations of the body and limbs were not found despite thorough fine-grain mapping. Responses possibly representing a vestige of primary sensory cortex, and mechanosensory responses in claustro-cortex, were also observed.     

Reversible blockade of vestibular evoked activity in the chick

Vestibular evoked potentials (VsEP) were recorded from young chickens following bilateral intralabyrinthine injections of Tetrodotoxin (TTX). The purpose of this study was to document the long term effects of TTX on the electrophysiological activity of the vestibular system. VsEP components were eliminated within 30 min of TTX injections. Twelve hours post-treatment the early waves of the response began to emerge from the background noise. Recordings completed 24 h after the manipulation were not different from baseline responses. Our results indicate that TTX is a useful substance for reversibly blocking vestibular afferent pathways without permanently damaging the labyrinth or neural components. In addition, VsEP is an appropriate tool to objectively evaluate vestibular system function. Their combination can be applied to study the significance of afferent influences on the development and function of vestibular nuclei.     

Action of delta-9-tetrahydrocannabinol on the binding of estradiol to uterine and other tissues in rats

In the present paper three binding studies have been done to evaluate any possible interaction of delta-9-tetrahydrocannabinol (delta-9-THC) with estrogen in adult female rats. (1) Treatment with THC for 10 consecutive days and eventual binding studies with the uterine cytosol receptors in the presence of estradiol indicate that the drug has almost no effect on the binding affinity of the hormone. (2) In vitro incubation of cytosol receptors in the presence of different concentrations of THC further shows that there is no change in binding affinity to estradiol as well. (3) Treatment of ovariectomised rats with delta-9-THC and subsequently with radioactive estradiol indicates that binding of estradiol in most organs (viz. the uterus, vagina, liver, hypothalamus, pituitary, fallopian tube, kidney and adrenal) remains unaffected. The present paper therefore shows that delta-9-THC does not appear to alter the binding of estradiol to its receptors in any way. Hence, the antiestrogenic action previously reported to be exerted by the drug may be due to its direct action on the hypothalamo-pituitary-gonadal axis and not due to any inhibitory action at the steroid receptor level.