[Implantation of flakes of castor oil resin in rat dental alveolus]. / Implante de um floculado de resina de mamona em alvéolo dental de rato.

The purposes of the present study were: 1) to investigate the biocompatibility of a natural resin (made of fatty acids extracted from Ricinus communis) implanted in the dental alveolus of rats and 2) to verify any possible interference of that material in the osseous healing following tooth extraction. The resin (AUG-EX, Poliquil Araraquara Polímeros Químicos LTDA, Araraquara--SP) was placed inside de alveoli immediately after extraction of the upper right incisors. The animals were sacrificed 1, 2, 3 and 6 weeks after extraction or extraction + implantation. The hemi-maxillae were decalcified and processed for paraffin embedding. Longitudinal 6-micrometer-thick semi-serial sections stained with hematoxylin and eosin were obtained. Histologic examination showed particles of irregular shape and variable size (700-1200 microns) localized in the medium/cervical alveolar thirds, with a scanty but persistent foreign body reaction. From the second week on, as the relative volume of bone trabeculae increased, it was seen in close contact with the surface of the implanted material in some regions. Histometric analysis (differential point counting method), used to quantify the healing process in the apical third, showed a small but significant decrease (13%-20%) in new bone formation in the implanted rats. In conclusion, the results show that, in spite of its biocompatible nature, the studied resin hinders the post-extration healing process.

The importance of glucose for the freezing tolerence/intolerence of the anuran amphibians Rana catesbeiana and Bufo paracnemis

Several species of terrestrially hibernating frogs, turtles and inserts have developed mechanisms, such as increased plasma glucose, anti-freeze proteins and antioxidant enzymes that resist to freezing, for survival at subzero temperatures. In the present study, we assessed the importance of glucose to cryoresistance of two anuran amphibians: the frog Rana catesbeiana and the toad Bufo paracnemis. Both animals were exposed to -2 degrees Celsius for measurements of plasma glucose levels, liver and muscle glycogen content, haematocrit and red blood cell volume. Frogs survived cold exposure but toads did not. Blood glucose concentration increased from 40.35 + 7.25 to 131.87 + 20.72 mg/dl (P < 0.01) when the frogs were transferred from 20 to -2 degrees Celsius. Glucose accumulation in response to cold exposition in the frogs was accompanied by a decrease (P < 0.05) in liver glycogen content from 3.94 + 0.42 to 1.33 + 0.36 mg/100 mg tissue, indicating that liver carbohydrate reserves were probably the primary carbon source of glucose synthesis whereas muscle carbohydrate seems unimportant. In the toads, the cold-induced hyperglycaemia was less (P < 0.05) pronounced (from 27.25 + 1.14 to 73.72 + 13.50 mg/dl) and no significant change could be measured in liver or muscle glycogen. Cold exposition had no effect on the haematocrit of the frogs but significantly reduced (P < 0.01) the haematocrit of toads from 20.0 + 2.1 per cent to 5.8 + 1.7 per cent due to a decreased red blood cell volume (from 1532 + 63 70 728 + 87 mm3). When toads were injected with glucose, blood glucose increased to levels similar to those of frogs and haematocrit did not change, but this failed to make them cryoresistent. In conclusion, the lack of cold-induced glucose catabolism may not be the only mechanism responsible for the freeze intolerance of Bufo paracnemis, a freeze-intolerant species.

Clinical and histological evaluation of granuloma gravidarum: case report.

Granuloma gravidarum is a benign lesion of the oral mucosa which occurs during pregnancy. This case report presents the clinical and histological evaluation and treatment of a granuloma gravidarum in a patient in the 9th month of pregnancy.

Histologic and histometric evaluation of rat alveolar wound healing around polyurethane resin implants.

The biocompatibility of polyurethane resin-implants derived from castor bean (Ricinus communis) was analyzed in the rat dental alveolus. Histometric evaluation of trial areas adjacent to the implants showed, by week 1, the polymer granules encircled by a conspicuous capsule and surrounded by immature connective tissue. By weeks 2 and 3, the implants were surrounded by less prominent fibrous capsules and most of the tested area was occupied by mature trabecular bone. By week 6, the fibrous capsule was thinner and the tested area was almost totally covered with bone, which in several places was in close contact with the implants. The results suggest that the material is compatible, as it was progressively integrated into alveolar bone in the wound-healing process.

Light and scanning electron microscopic study of the digestive tract in the catfish Pseudoplatystoma Corruscans Agassiz, 1829 (Pisces, Pimelodidae)

O trato digestivo do surubin Pseudoplatystoma corruscans foi estudado morfologicamente utilizando a microscopia de luz e eletrônica de varredura (MEV), além de técnicas histoquímicas. O epitélio estratificado do palato e faringe está constituído de uma camada basal com células indiferenciadas de núcleos elípticos de posiçäo central; uma camada média constituída de células intermediárias indiferenciadas, células gigantes acidófilas e células mucosas; e uma camada superficial de células achatadas. O esôfago apresenta estrutura semelhante, com células gigantes acidóficas menos numerosas e células poilimorfonucleares entre as células da camada basal, ao MEV, o palato evidenciou vários sulcos, sendo que a porçäo superficial está constituída de células hexagonais ou poligonais, em cuja área apical está presente as microcristas. A parte superficial da faringe apresenta células com microcristas dispostas concentricamente. O esôfago mostrou pregas longitudinais complexas, um epitélio estratificado cujas células apresentam microcristas irregulares. Os carbohidratos presentes nas células do tracto digestivo foram identificados como sendo mucosubstâncias neutras e ácidas

[Hemangioendothelioma of the lip]. / Hemangioendotelioma do lábio.

Hemangioendothelioma is a relatively uncommon tumor of the oral cavity. This article reviews the literature on hemangioendothelioma and presents one additional case of this neoplasm found on the lip.