The South African journal of medical sciences最新文献

Techniques used in the research laboratory for the microbiological diagnosis of infantile gastroenteritis are described. These techniques are in essence experimental models of the three pathogenetic mechanisms of bacterial diarrhoea. From the clinical bacteriological standpoint, although there is little difficulty with the identification of enteropathic bacteria such as Salmonella and Shigella, the differentiation of enteropathic strains of Escherichia coli from commensal strains is not possible with present routine bacteriological procedures. Possible adaptations of these experimental techniques to the routine laboratory are discussed. At present, negative-staining electron microscopy is the only way in which reoviruslike particles, the most important viral pathogen in infantile gastroenteritis, may be detected. Because of its relative simplicity this examination is strongly recommended in all cases of infantile gastroenteritis.

Comparative polyacrylamide electrophoretic studies were done on the cerebrospinal fluid (CSF) of rabbits, pigeons, frogs and snakes. The results are compared to the pattern of normal human CSF and it is suggested that significant differences between the human and lower animals might exist.

The diencephalon of the vervet monkey (Cercopithecus aethiops) is described and compared with that of other primates, particularly the macaque monkey (Macaca mulatta). In the vervet monkey, the thalamus is divided into six nuclear groups: anterior, midline, medial, dorsolateral, ventrolateral and posterior. The anterior nuclear group shows a regressive nucleus anterodorsalis and a poorly defined demarcation between the nuclei anteromedialis and anteroventralis. There is a large interthalamic adhesion in which the ventral region containing nuclei centralis medialis, interventralis and reuniens, shows more regression than the dorsal region consisting of nuclei parataenialis and paraventralis. As the nucleus medialis ventralis is not present, the nucleus medialis dorsalis is described as the nucleus medialis; this is clearly differentiated into three parts, each part showing different cytological and architectonic features. The nucleus centrum medianum is larger and better developed than that of lower primates but is not entirely demarcated from the nucleus parafascicularis. The pulvinar is an enormous outgrowth from the dorsolateral thalamic nuclei. The ventrolateral thalamic nuclei are well differentiated from one another: a distinct nucleus ventralis dorsomedialis is present and appears to possess definite topographical and cytological differences from those of the other ventrolateral nuclei. The nucleus ventralis posteromedialis is further differentiated into a magno- and a parvocellular part. The nucleus ventralis posteroinferioris is a distinct entity. The lateral geniculate body shows a definite differentiation into two nuclei: pregeniculate and lateral geniculate nuclei. The lateral geniculate nucleus is a six-layered structure which is of the inverted type; it has undergone a lateral rotation through an anteroposterior axis from a dorsal position in the prosimian thalamus to its present ventral position in the higher primate thalamus. The medial geniculate body is not laminated as is the lateral geniculate nucleus; it consists of a small dorsomedial magnocellular and a large ventrolateral parvocellular part.

The surfaces of the developing secondary palatal shelves and palate, in Wistar strain albino rats, were examined using scanning electron microscopy. Beginning on the 16th day after insemination there was a progressive degeneration of the cell surfaces on the medial aspect of the shelves. This took the form of a loss of surface microvilli and intercellular boundaries accompanied by the appearance of clefts between the cells. Fusion of the palate was complete by the 18th day and two epithelial zones could be recognized in the soft palate. The cell surface degeneration is possibly an essential change prior to shelf fusion.

1-beta-D Arabinofuranosylcytosine (ara-C) has been shown to strongly inhibit the uptake of [13h] thymidine into hamster embryo fibroblasts and transformed hamster embryo cells.

Serum immunoglobulin G, M and A levels were measured in 106 White patients with acute virus-A (hepatitis-B surface antigen-negative) hepatitis and 27 White patients with acute virus-B (hepatitis-B surface antigen-positive) hepatitis and compared with the values previously obtained in Black patients with these diseases. The mean serum IgM level in the White patients with virus-A hepatitis was significantly higher than that in virus-B hepatitis (p less than 0,001). This difference was much more obvious than that in Black patients, mainly due to a much lower mean serum IgM response in Black patients with virus-A hepatitis. The reason for the blunted IgM response in Black patients with virus-A hepatitis is not known, but it may be related to a difference in the reaction against altered host tissues rather than any difference in antibody production against the virus per se. The mean serum IgG and IgA levels were not significantly different in the White patients with virus-A and virus-B hepatitis and they were lower than the corresponding figures in Blacks.

Inactive endometrial patterns occur frequently in the post-partum period and their occurrence is modified by the breast-feeding practice. An abnormal endometrium pattern, viz., cystic hyperplasia, may occur more frequently in non-lactating women and in patients using oestrogens, especially long-acting preparations, for lactation suppression. Post-ovulatory endometrial patterns in lactating women occur infrequently during the puerperium. The implications of these findings are discussed.

The presence of fast-migrating, low-molecular weight components in normal rat thyroglobulin, iodine-poor rat thyroglobulin and normal bovine thyroglobulin was investigated by polyacrylamide gel electrophoresis in sodium dodecyl sulfate. When normal and iodine-poor rat thyroglobulin were extracted in the presence of phenylmethanesulfonyl fluoride, a serine protease inhibitor, very few components migrating faster than the 12S half-molecule were found. In normal bovine thyroglobulin no effect of the protease inhibitor on the formation of fast-moving components was found; however, prior freezing of the glands greatly influenced the presence of these components. Thyroglobulin obtained from bovine glands without any prior freezing, contained no noncovalently-bound band migrating faster than 12S.

Extirpation of the endolymphatic anlage of the ear vesicle or that part of the ear placode which develops into the endolymphatic anlage in chick embryos, resulted in the absence of the endolymphatic system. In specimens of which the endolymphatic anlage was removed on the fourth day, healing of the wound was completed soon after the fifth day of incubation. Most of these experimental animals developed endolymphatic hydrops at a later stage. However, where healing was delayed after the fifth day, the open wound acted as an escape route for the endolymph (thus preventing further closure) which at that stage (or soon after) reached an appreciable volume.

An electrical apparatus was designed to record continuously the feeding activity of either a colony of 30 fruit bats (Rousettus aegyptiacus) or single bats in captivity. The endogenous feeding activity rhythm was synchronized by change in the external light-dark cycle. During June to August (winter), the bats consumed an average of 96 g sliced banana, equal to 76 g wet weight/100 g body weight per 24 hours or 15 g dry weight/100 g body weight per 24 hours. The feeding period began shortly after sunset and continued for 10,6 h. Feeding consisted of 6-14 separate small meals. The mean or overall feeding rate was 9,1 g banana/h, and the feeding rate during the first 3 h, 13,1 g/h. The bat regulated its food intake by varying the rate of food consumption and not by changing the duration of the feeding period. It is suggested that clustering of the bats may influence the caloric intake by reducing the energetic cost of thermoregulation.