Ibotenate lesion of the medial hypothalamus alters the salt intake and pressor responses to activation of the median preoptic nucleus in rats.

We investigated the influence of ibotenic acid lesions of the medial hypothalamus (MH) on salt appetite and arterial blood pressure responses induced by angiotensinergic and adrenergic stimulation of the median preoptic nucleus (MnPO) of rats. Previous injection of the adrenergic agonists norepinephrine, clonidine, phenylephrine, and isoproterenol into the MnPO of sham MH-lesioned rats caused no change in the sodium intake induced by ANG II. ANG II injected into the MnPO of MH-lesioned rats increased sodium intake compared with sham-lesioned rats. Previous injection of clonidine and isoproterenol increased, whereas phenylephrine abolished the salt intake induced by ANG II into the MnPO of MH-lesioned rats. Previous injection of norepinephrine and clonidine into the MnPO of sham MH-lesioned rats caused no change in the mean arterial pressure (MAP) induced by ANG II. Under the same conditions, previous injection of phenylephrine increased, whereas isoproterenol reversed the increase in MAP induced by angiotensin II (ANG II). ANG II injected into the MnPO of MH-lesioned rats induce a decrease in MAP compared with sham-lesioned rats. Previous injection of phenylephrine or norepinephrine into the MnPO of MH-lesioned rats induced a negative MAP, whereas pretreatment with clonidine or isoproterenol increased the MAP produced by ANG II injected into the MnPO of sham- or MH-lesioned rats. These data show that ibotenic acid lesion of the MH increases the sodium intake and pressor responses induced by the concomitant angiotensinergic, alpha 2 and beta adrenergic activation of the MnPO, whereas alpha 1 activation may have opposite effects. MH involvement in excitatory and inhibitory mechanisms related to sodium intake and MAP control is suggested.

Effect of alpha, alpha'-dipyridyl on the basement membrane of tooth germs in vitro.

Dipyridyl inhibits the morphogenesis of tooth germs, but the germs recover when transferred to control medium. In this study, the effect of dipyridyl on basement membrane was investigated in vitro. The basal lamina was always present, but the subjacent collagen fibrils disappeared in the presence of dipyridyl and reappeared during recovery in control medium.

Biocompatibility testing of a posterior composite and dental cements using a new organ culture model.

Mandibular first molars from day 14 and 17 mouse embryos were cultured in vitro for 7 days in chemically defined Pratt's medium in a submerged culture system. Ameloblast and odontoblast polarization and morphogenesis occurred in the control tooth germs. Discs of Occlusin, Silicate, ChemFil, IRM and Dycal were exposed to the culture system as either fresh material, leached discs (by pre-incubation in media) or the leachate from the incubated discs. Their effects on dental differentiation were assessed histologically. Day 17 tooth germs were slightly more sensitive to the effects of the exogenous agents than day 14 tooth germs. In general, silicate and ChemFil were toxic, IRM was slightly less toxic and the major effect was from the leachate. Dycal was toxic but most of this effect resulted from pH changes in the leachate. Occlusin was the most biocompatible material tested. Only a very mild adverse effect was detected, and this appeared to be caused by an agent (not a pH change) released into the leachate.

Imaging of infections and inflammatory conditions of the spine.

The lack of specific clinical, laboratory, and radiologic findings in patients with a disease as potentially debilitating as infectious spondylitis is challenging. Biopsy will frequently need to be performed but is itself often nondiagnostic and is not without risk. Therefore, identification of findings, often subtle, that strongly favor other entities in the differential may be of just as much clinical import as identifying findings worrisome for infection, particularly in the subset of patients who otherwise are felt unlikely to have a disc space infection. Radiography and magnetic resonance (MR) imaging are complementary imaging techniques and both should be performed. The pertinent vascular anatomy of the spine; the epidemiologic, microbiologic, and clinical features of infectious spondylitis; and the role of imaging are reviewed in this article. Particular emphasis is placed on imaging differentiation of the various discovertebral disease processes.

[Effect of cyclophosphamide on the development of tooth germs transplanted to the anterior eye chamber of mice]. / Efeito da ciclofosfamida sobre o desenvolvimento de germes dentais de molares transplantados para a câmara anterior do olho de camundongos.

Mice foetus were killed between 13 and 16 days of the gestational period and their molar tooth germs grafted into the anterior chamber of the eye. The hosts were injected either with 6.25 mg/Kg or with 125 mg/Kg of cyclophosphamide and killed 15 days later. The cyclophosphamide irreversibly, interferes on tooth germ development causing either its total degeneration or an alteration on its morphology forming hypodeveloped tooth germs; its action is directly proportional to the foetus age and to the dose used; it does not induce the formation of osteodentin while some predentin partial cell inclusion may occur.

[Effect of cyclophosphamide on the development of incisor tooth germs in mice]. / Efeito da ciclofosfamida sobre o desenvolvimento de germe dental do incisivo do camundongo.

Thirty six female mice were injected on the 12th day of the gestational period with 0.2 ml of distilled water (control group) or of an acqueous solution containing either 30 mg/Kg or 50 mg/Kg of body weight of cyclophosphamide (treated group). The animal were killed at 24, 48, 72, 96 and 120 hours after the injection and 3 days after birth. It was verified that cyclophosphamide interferes on the tooth germ development and that this effect is in directly ratio of the doses used.