Evidence for the presence of osmoreceptors in medulla of the dog

Hypertonic solutions of different substances were injected into the vertebral artery of dogs anesthetized with chloralose, preventing their access to the hypothalamic osmoreceptors by ligating the basilar artery and both the external carotid arteries. The hypertonic solution of sodium chloride produced graded inhibition of water diuresis and a concomitant rise in plasma antidiuretic hormone (ADH) level; hypertonic solution of glucose produced lesser effect. Hypertonic urea solution, on the other hand, did not alter the course of water diuresis. It was concluded that osmoreceptors are also present in the medulla which sense the changes in blood osmolarity and accordingly modify the ADH release.     

Central cholinergic and adrenergic mechanisms in the release of antidiuretic hormone

1. Studies on the urine outflow, blood ADH concentration and electrolyte excretion were carried out in alpha-chloralose anaesthetized hydrated dogs; the agonists and antagonists of specific cholinoceptors and adrenoceptors were injected by the intracerebroventricular technique, to delineate the role of the C.N.S. receptors in the control of ADH secretion.2. Central injection of acetylcholine elicited a dose-dependent antidiuretic response which was associated with an increase in the blood ADH titre. Central atropinization partially blocked the antidiuretic response. The remaining antidiuretic response was reversed to a diuretic one by further pretreatment with phenoxybenzamine. The diuretic response thus obtained could be blocked by propranolol.3. The alpha-adrenoceptor agonists, phenylephrine and noradrenaline, induced dose-dependent antidiuretic responses with a concomitant rise in blood ADH concentration. Their effect could be blocked by pretreatment centrally with phenoxybenzamine. Low doses of adrenaline induced a diuretic response and a decrease in blood ADH concentration, higher doses elicited a dose-dependent antidiuretic response and increase in the titre of ADH in blood. Central phenoxybenzamine pretreatment reversed the antidiuretic effect of high doses of adrenaline to a diuretic effect which could be blocked by propranolol.4. Isoprenaline elicited a dose-dependent diuretic response and a decrease in blood ADH titre and propranolol competitively blocked the effect of isoprenaline.5. It is concluded that central muscarinic cholinoceptors and the alpha-adrenoceptors are concerned in the release of ADH, whereas the beta-adrenoceptors are concerned with inhibition of ADH release.     

An experimental investigation of dependence liability of methaqualone in rats

In the present study, rats were kept on a semifluid diet, and methaqualone and phenobarbitone were added to the diet of different groups of animals. Every week the doses of the drugs were increased and daily records of body weight, mean rectal temperature and spontaneous motor activity were maintained. Tolerance to both the drugs was discernible in the first and second week, when the animals received 138.3 and 284.4 mg/kg/day of methaqualone and 96.8 and 178.6 mg/kg/day of phenobarbitone, respectively. In the third week the doses were further increased to 392.6 mg/kg/day of methaqualone and 235.9 mg/kg/day of phenobarbitone and at the end of this week although there was gradual and partial recovery, statistically significant (P<0.05) lowering of mean rectal temperature, body weight and spontaneous motor activity was observed in comparison to a control group of rats. After the third week when the drugs were withdrawn from the diet methaqualone treated rats exhibited increased susceptibility to audiogenic stimuli. Rats similarly treated with phenobarbitone showed a greater susceptibility to audiogenic stimuli, and in addition exhibited increased motor activity and a precipitous decrease in body weight. The results of this study are suggestive of a milder degree of dependence liability in methaqualone as compared with barbiturates.     

Persistence and Transformation of Thiamethoxam, a Neonicotinoid Insecticide, in Soil of Different Agroclimatic Zones of India

No abstract available.     

A Case of Branch Retinal Artery Occlusion following Uneventful Phacoemulsification

We would like to present a case of branch retinal artery occlusion following uneventful phacoemulsification, possibly caused by sub-Tenon''s anaesthesia. There were no predisposing general health problems. There are two possible mechanisms: (1) mechanical effect of the bolus anaesthetic; (2) pharmacologically mediated changes in the vascular calibre. The latter mechanism is much more probable, because of the vasoconstrictive properties of both medications used. This is the first reported case of branch retinal artery occlusion after sub-Tenon''s anaesthesia with preservative-free medications.Key words: Phacoemulsification, Sub-Tenon''s anaesthesia, Branch retinal artery occlusion     

Dietary factors that promote or retard inflammation

Inflammation plays a pivotal role in all stages of atherosclerosis. Cardiovascular risk factors and metabolic syndrome are typified by low-grade inflammation. Intervention trials convincingly demonstrate that weight loss reduces biomarkers of inflammation, such as C-reactive protein (CRP) and interleukin (IL)-6. Limited studies have shown that certain dietary factors; oleic acid, alpha-linolenic acid, and antioxidants RRR-alpha-alpha tocopherol, reduce biomarkers of inflammation. Most of the studies with fish oil supplementation have shown null effects, and conflicting results have been reported with saturated and trans fatty acids, cholesterol, and soy intake. Much further research is needed to define the role of individual dietary factors on the biomarkers of inflammation and the mechanism of the anti-inflammatory effects of weight loss.     

Clustered functional MRI of overt speech production

To investigate the neural network of overt speech production, event-related fMRI was performed in 9 young healthy adult volunteers. A clustered image acquisition technique was chosen to minimize speech-related movement artifacts. Functional images were acquired during the production of oral movements and of speech of increasing complexity (isolated vowel as well as monosyllabic and trisyllabic utterances). This imaging technique and behavioral task enabled depiction of the articulo-phonologic network of speech production from the supplementary motor area at the cranial end to the red nucleus at the caudal end. Speaking a single vowel and performing simple oral movements involved very similar activation of the cortical and subcortical motor systems. More complex, polysyllabic utterances were associated with additional activation in the bilateral cerebellum, reflecting increased demand on speech motor control, and additional activation in the bilateral temporal cortex, reflecting the stronger involvement of phonologic processing.