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Biomedical subjects

B N Joshi

Publications and source records attributed to B N Joshi.

At least 37 records · Page 2Linked to original sources
PubMed1986

Adrenal-mediated depression of N-acetyltransferase activity and melatonin levels in the rat pineal gland.

N-acetyltransferase (NAT) is believed to be the rate-limiting enzyme in the synthesis of melatonin from serotonin in the pineal gland. Norepinephrine released from sympathetic nerve endings within the pineal gland stimulates NAT activity and, therefore, melatonin synthesis. When an animal is subjected to a stressful stimulus, it would be expected that the increase in plasma stimulus, it would be expected that the increase in plasma catecholamines originating from the adrenal medulla and/or the sympathetic nervous system would result in a stimulation of pineal NAT activity. Adult male rats were given a 1.5cc injection of physiological saline subcutaneously into the back leg. Compared to non-injected controls, animals stressed in this manner were shown to have significantly lower pineal melatonin content 10 min after the saline injection late in the light phase of the light/dark cycle (at 18.30 h-lights on at 07.00 h). To test this more thoroughly, a time course study was conducted during the dark phase (at 02.00 h-5 hours after lights out) when pineal NAT activity and melatonin levels are either increasing or elevated. NAT activity and melatonin levels in the pineal were significantly depressed in stressed animals as compared to controls by 10 min after the saline injection, and remained so until 60 min after injection. By 90 min they had returned to control values. In the next study the nighttime response of the pineal to stress was compared in intact and adrenalectomized rats. Adrenalectomy prevented the changes in NAT activity and melatonin content associated with the saline injection. Some factor, such as a catecholamine or corticosterone from the adrenal, seems to be eliciting the response in the pineal to the saline injection. It is not known if the factor is acting centrally or directly on the pineal gland.

Acetyltransferases↗
PubMed1986

A single 1- or 5-second light pulse at night inhibits hamster pineal melatonin.

Adult male Syrian hamsters maintained under 6-h light, 18-h dark cycles (lights out daily from 1200-0600 h) were exposed to either 1 or 5 sec light either 8 h (at 2000 h) or 12 h (at 2400 h) into the dark phase. The light had an irradiance of 32,000 microW/cm2. With both light pulse durations and at both times, melatonin levels were depressed to daytime values 30 min after the onset of the light pulse. Whereas pineal melatonin production eventually increased to high nighttime values in hamsters exposed to 1 sec light at either 2000 or 2400 h and in animals receiving a 5-sec light pulse at 2000 h, when the 5-sec light occurred at 2400 h, pineal melatonin levels remained low for the remainder of the night. Thus, both the placement and the duration of light exposure appear to be important in determining the ability of light to depress melatonin production in the Syrian hamster.

Animals↗
PubMed1986

Toxoplasma antibodies in local domestic animals.

211 sera obtained from domestic animals generally used for human consumption in this area, were tested for Toxoplasma antibodies by the Indirect Haemagglutination Test (IHA). Goat (34.4%) and pig sera (26.6%) showed a higher prevalence as compared to cattle (16.6%) and sheep (7.4%). Obviously, proper precautions at every stage of the preparation of a meat dish are necessary to avoid Toxoplasma infection.

Animals↗
PubMed1985

Superior cervical ganglionectomy results in the loss of pineal concretions in the adult male gerbil (Meriones unguiculatus).

Twelve weeks after bilateral superior cervical ganglionectomy, the number of pineal concretions in adult male gerbils was drastically decreased irrespective of photoperiodic treatment. These findings present further evidence that pineal concretions may be related to the metabolic activity of the gland. It is suggested that the pineal concretions of the gerbil are associated, in a yet unknown way, to the metabolism of the gland and that an active pineal is essential to maintain the large number of concretions seen in the normal state.

Animals↗
PubMed1985

Responsiveness of pineal N-acetyltransferase and melatonin in the cotton rat exposed to either artificial or natural light at night.

In three separate experiments, the effect of acute exposure to either artificial or natural light during darkness of pineal N-acetyltransferase (NAT) activity and melatonin content was studied in the cotton rat (Sigmodon hispidus). The exposure of animals to an artificial-light irradiance of 160,000 microW/cm2 during darkness for either 1 s, 5 s, or 30 min was followed by a precipitous decline in pineal NAT activity and melatonin content when measured at either 15 or 30 min after light onset. When cotton rats were acutely exposed to light at night for 5 s, irradiances of either 3.2, 32, 320, and 3,200 did not suppress either pineal NAT or melatonin 30 min later; however, if the 5-s exposure had an irradiance of either 32,000 or 160,000 microW/cm2, the pineal enzyme activity and indole content were depressed. Moonlight, which had a maximal irradiance of 0.32 microW/cm2, was unable to suppress pineal NAT activity and melatonin content even when the animals were exposed to the moonlight for 30 min. The treatment of cotton rats with either norepinephrine or its agonist, isoproterenol, before their exposure to light at night retarded slightly the suppressive effect of light on the pineal constituents measured. Also, these drug treatments suppressed the pre-exposure levels of both NAT activity and melatonin content in the cotton rat pineal gland.

Acetyltransferases↗
PubMed1985

Diurnal sensitivity of the neuroendocrine-reproductive axis to the antigonadotrophic influence of melatonin in male Syrian hamsters with experimentally altered cortisol rhythms.

Two different experimental models were used to test if a temporal relationship exists between the rhythm of adrenal steroid secretion and the vulnerability of the hamster reproductive system to short photoperiod exposure or to the daily afternoon injection of melatonin. In the first experiment adrenalectomized hamsters were implanted with a cortisol pellet to provide a sustained, rather than rhythmic, level of the hormone. The animals were either placed in short photoperiod or given a daily afternoon melatonin injection. In both cases the gonads underwent atrophy. In the second experiment adrenalectomized hamsters were given a cortisol injection either in the morning (approx. 8 hr before the subsequent afternoon injection of melatonin) or in the afternoon (approx. 1 hr before the subsequent melatonin injection). Measurements of testicular and accessory organ weights 7 weeks later indicated regression of the reproductive system in both the groups when compared with their appropriate controls. Depressed levels of plasma LH, PRL, testosterone and thyroxine (T4) in these animals confirmed the melatonin induced gonadal collapse. The results suggest that apparently there is no temporal correlation between the rhythm of secretion of the adrenal steroids and the responsiveness of the reproductive system to late afternoon injection of melatonin. Interestingly, all the adrenalectomized cortisol injected control animals (not receiving melatonin) had depressed plasma LH and PRL while the testicular weights and plasma testosterone titers remain unaffected.

Adrenalectomy↗
PubMed1983

Assessment of burn wound sepsis by swab, full thickness biopsy culture and blood culture--a comparative study.

Fifty patients with burns ranging from 30 to 50 per cent of their body surface area were monitored for sepsis throughout their hospital stay using swab, blood and full thickness biopsy culture techniques. The relative merits of these techniques in the diagnosis of burn wound sepsis were evaluated. Only 62.5 per cent of the patients with a positive surface culture showed signs of clinical sepsis, while 87.5 per cent of the patients with significant bacterial count on biopsy culture showed signs of clinical sepsis. A decrease in bacterial count on follow up correlated with clinical improvement while a count of 10(8) orgs/gm indicated a bad prognosis. Wound surface cultures, though the simplest method gave poor indication of the organisms invading into the burn wound. Blood cultures were of only prognostic value. Full thickness biopsy culture and quantification of the number of bacteria in the burn wound was felt to be the best method for rapid diagnosis and for assessing the progress of burn wound infection.

Bacteriological Techniques↗
PubMed1983

Investigation report of an epidemic of typhoid fever.

An explosive common-source epidemic of typhoid fever, probably the world's biggest, occurred in Sangli Town (Maharashtra State), India, between December 1975 and February 1976 when, with the incidence rate of 6.59% over this 12-week period, probably more than 9000 cases occurred in a population of about 135 000. Faecal contamination of municipal water supply, which was receiving unsatisfactory and inadequate chlorine treatment, was responsible for the epidemic. Contamination at suitable intervals resulted in a heavy build-up of S. typhi in the population. Massive central contamination of the ill-maintained municipal water-supply system with faecally-contaminated waste-water from a population of about 37 000, in which there were thought to be over 250 typhoid cases, ultimately resulted in the explosive epidemic. The episode underlines the importance of proper maintenance of water supply and excreta disposal systems.

Adolescent↗
PubMed1980

A histochemical study on the adrenal components of the teleost Cirrhinus mrigala (Ham.).

The adrenal components of C. mrigala are embedded in the pronephric cephalic kidney around the post cardinal vein. The cortical cells responded positively to the lipids, ascorbic acid, delta 5-3 beta-HSD, G-6-PD, MAO, acid and alkaline phosphatase tests. The presence of intense MAO activity may suggest the possible involvement of monoamines in the adrenocortical function. Localization of lipids and delta 5-3 beta-HSD show the sites of corticosteroid synthesis. In the chromaffin cells, MAO, acid and alkaline phosphatase activity was moderate whereas they gave a strong reaction to ascorbic acid test in comparison to the cortical cells. Noradrenaline (NA) and adrenaline (A) storing cells were differentiated adopting glutaraldehyde silver, dichromate and iodate techniques. NA and A storing cells are almost totally depleted of their contents after reserpine treatment. The histochemical response of the adrenal gland of this species is largely comparable to that of higher vertebrates.

Adrenal Glands↗