EXPOSICAO DE CIRURGIOES-DENTISTAS AO MERCURIO

The professional exposure of dental surgeons to mercury has attracted a great deal of attention from governmental organs and institutions in different countries. Considering that the normal ratio is 10 μg/1000 ml of urine, it was verified from tests that 72.7% of the professionals working in the dental practice in the city of Araraquara (SP) Brazil, show mercury levels above this limit. These results demonstrated the almost complete unawareness of many dentists to mercury and, consequently, precautionary measures were almost nonexistent.

Interaction between areas of the central nervous system in the control of water intake and arterial pressure in rats

1. Water intake induced by injection of 0.2 M-NaCl into the lateral preoptic area was increased by the injection of angiotensin II into the subfornical organ of rats. The injection of hypertonic saline solution into the subfornical organ increased water intake. However, the increase was lower than when the solution was injected into the lateral preoptic area. The injection of 4 μg angiotensin II into the lateral preoptic area further augmented this effect. 2. Injection of angiotensin II into the subfornical organ caused a rise in blood pressure which preceded the thirst-inducing effect. The injection of 0.2 M NaCl into the subfornical organ caused no changes in blood pressure, whereas the injection of angiotensin II into the lateral preoptic area caused some increase. 3. Dehydration of the lateral preoptic area by means of 0.2 M NaCl in combination with intravenous infusion of angiotensin II caused a summation of effects in terms of the water intake, without changing cardiovascular alterations induced by the infusion of angiotensin II. A summation of effects in the water intake, but not in blood pressure, was also observed when 0.5 M NaCl was infused intravenously in combination with the injection of angiotensin II into the subfornical organ and into the lateral preoptic area. 4. The results indicate that there are interactions between the subfornical organ and lateral preoptic area in the regulation of cardiovascular and thirst mechanisms.

Effect of cholinergic and adrenergic stimulation of the subfornical organ on water intake

Cholinergic and adrenergic agonists and antagonists were injected directly into the subfornical organ (SFO), via implanted cannulae, and the volume of water ingested was recorded over a period of 1 hour after injection. Application of 2 nmol carbachol caused intense water intake in 100% of the animals (8.78±0.61 ml), with a very short intake latency. When the 2 nmol carbachol dose was preceded by increased doses of atropine, a progressive reduction in water intake was observed, with complete blockage of the thirst-inducing response to carbachol at the 20 nmol dose level with atropine. Followed by several doses of hexamethonium, the water intake caused by application of 2 nmol carbachol was reduced, although the response was not totally blocked. Injection of 80 nmol of nicotine had a significant thirst-inducing inducing effect in 50% of the animals studied (1.06±0.18 ml) and increase in water intake was further reduced by application of increased doses of hexamethonium. Raising the dose levels of noradrenaline into th SFO caused an increase in water intake although to a lesser degree than was observed after carbachol injection. When the 40 nmol dose of noradrenaline was preceded by increased doses of propranolol (5 to 40 nmol), there was a gradual reduction in water intake, with total blockage at the 40 nmol dose. Application of phentolamine in doses of 10 to 80 nmol caused no reduction in water intake after 40 nmol of noradrenaline. Application of isoproterenol at doses from 20 to 160 nmol into the SFO caused a dosedependent increase in water intake which was blocked by previous applications of propranolol. These results support the hypothesis that the water intake caused by chemical stimulation of the SFO is mainly due to muscarinic cholinergic receptors, although the influence of nicotinic receptors or participation of adrenergic mediation should not be ruled out. © 1984.

The effect of Ketoconazole on experimental paracoccidioidomycosis in the Syrian hamster: immunological and histopathological study

The effect of Ketoconazole (KTZ) on the hamster experimental intratesticular paracoccidioidomycosis was studied employing different treatment schedules. KTZ long course treatment beginning at an early stage of the infection was effective in preventing fungal proliferation, dissemination to lymph nodes, spleen and kidneys, and in maintaining low levels of humoral and cellular specific immune responses. KTZ short course treatment starting at an advanced stage of disease resulted in a more severe histopathological picture without significant changes in the immunological profile. The drug prolonged the life span of hamsters infected with Paracoccidioides brasiliensis, but did not prevent mortality. Toxic necrosis of the bone marrow occurred in normal animals receiving 120 mg/kg/day of KTZ but with lower doses no morphologic alterations were observed in heart, lungs, kidneys, adrenals, spleen, liver, intestine or bone marrow. © 1984 Dr W. Junk Publishers.