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Biomedical subjects

A Peters

Publications and source records attributed to A Peters.

At least 289 records · Page 16Linked to original sources
PubMed1979

[Epidemiology of hepatitis A: serological study among a French population (author's transl)].

To investigate the prevalence and distribution of antibodies to hepatitis A antigen (anti HAV Ab) we tested 848 French people living mainly but not exclusively in Franche-Comté (East of France). In Franche-Comté, 76 per cent of all the subjects studied were found to be anti-Hav ab positive, as determined by specific radio-immuno-assay. The rate of antibody detection was correlated with age; the prevalence was low (38 per cent) in childhood and adolescence, gradually increasing throught adulthood, and reaching its peak level (greater than 95 per cent) in people aged 40 and above. Anti-HAV Ab was detected more frequently in farmers (89 per cent), factory workers (87 per cent) and office employees (80 per cent) than in hospital personnel (53 per cent). Socioeconomic differences were found to be important in young people but tended to disappear at about 40 years of age. No difference was found in the prevalence of anti-HAV Ab between national servicemen from Franche-Comté and those from other regions. In 3 per cent of cases anti-HBs Ab was associated with the presence of anti HAV Ab. The subject possessing anti HBS Ab had the same prevalence of anti-HAV Ab (75 per cent) as those without (76 per cent).

Adolescent↗
PubMed1979

The bilaminar and banded distribution of the callosal terminals in the posterior neocortex of the rat.

After callosal sectioning, the callosal connections of the posterior neocortex of the rat cerebral hemisphere were demonstrated using the Fink-Heimer technique. Serial frozen sections of the whole brains were cut in transverse, horizontal, and tangential planes. In tissue sections, degenerating terminals were concentrated in two distinct laminae within the depth of the cortex. In addition the terminals had a patchy distribution. The degeneration was marked on projection drawings of serially arranged sections, and subsequent reconstruction showed the terminal degeneration to be distributed in bands. Five dorsoventrally oriented bands of terminals were present in areas 39, 41 and 36 collectively, and a rostrocaudal band in area 20. In area 17 terminations were apparently absent except at its borders with areas 18, 18a and 7. The degenerating callosal terminals within these areas produced a circumferential band around area 17. The findings are discussed with respect to the significance of these patterns of corticocortical connections.

Afferent Pathways↗
PubMed1979

The choroid plexus of the mature and aging rat: the choroidal epithelium.

The choroid plexus of mature and old rats has been examined by both scanning and transmission electron microscopy. It has been shown that the macrophages lying upon the ventricular surface of the choroid plexus have a close association with burr-like protrusions that extend from the apical surfaces of the choroidal epithelial cells. These protrusions have a dark cytoplasm filled with vesicles and tubules, and projecting from them are thin, shrunken microvilli. It is suggested that these protrusions are phagocytosed by the macrophages and that they are the source of some of the inclusions which become increasingly common within the cytoplasm of macrophages in older rats. The lateral surfaces of the choroidal epithelial cells have also been examined in the scanning electron microscope after exposure of the surfaces by dissection. In such preparations it is apparent that the elaborate interdigitations between adjacent cells are effected by irregular and vertically arranged folds confined to the basal portions of the lateral cell surfaces. Lastly, it has been shown that at the junction between the choroid plexus and the ependyma in the lateral ventricle, there are two modes of transition between the choroidal and ependymal epithelia. In one, typical choroidal and ependymal epithelial cells lie next to each other to produce a distinct and continuous bondary. In the other mode the boundary is also continuous, but there are modified ependymal cells present. These modified cells have short, relatively sparsely distributed microvilli and not more than one or two cilia.

Aging↗
PubMed1979

The projection of the lateral geniculate nucleus to area 17 of the rat cerebral cortex. V. Degenerating axon terminals synapsing with Golgi impregnated neurons.

The sites of termination of afferents from the lateral geniculate nucleus to layer IV and lower layer III in area 17 of the rat visual cortex have been determined by use of a combined degeneration--Golgi/EM technique. Degeneration of geniculocortical axon terminals was produced by making lesions in the lateral geniculate body. After the animals had been allowed to survive for two days, the ipsilateral visual cortex was removed and impregnated by the Golgi technique. Suitably impregnated neurons and their processes in layer IV and lower layer III were then gold-toned and deimpregnated for examination in the electron microscope. A search was made for synapses between degenerating axon terminals and the gold-labelled postsynaptic neurons. Geniculocortical synapses were found to involve: (1) the spines of basal dendrites as well as those of proximal shafts and collaterals of apical dendrites of layer III pyramidal neurons; (2) the spines of the apical dendritic shafts and collaterals of layer V pyramidal neurons; (3) the perikaryon and dendritic spines of a sparsely-spined stellate cell; and (4) the perikaryon and dendrites of a smooth, bitufted stellate cell. In view of this variety of postsynaptic elements it is suggested that all parts of the perikarya and dendrites of neurons contained in layer IV and lower layer III which are capable of forming asymmetric synapses can be postsynaptic to the thalamic input. Finally, an analysis of the known neuronal interrelations within the rat visual cortex is presented.

Afferent Pathways↗
PubMed1979

Binding of bovine immunoglobulins to pituitary intermediate lobe cells.

Basophilic granular cells of the bovine pituitary intermediate lobe and intraglandular colloid show an affinity for immunoglobulin IgG, IgA, and IgM. The cells were identified by direct and indirect fluorescent staining methods using blocking tests as controls. It is suggested that these cells may play some role in the synthesis and release of immunoglobulins or their determinants to the intact Ig molecule.

Animals↗
PubMed1978

The forms of non-pyramidal neurons in the visual cortex of the rat.

Rapid Golgi preparations from area 17 of young adult rats have been studied to determine the morphology and distribution of non-pyramidal neurons. Such cells were observed in all of the cellular laminae of the cortex, but were particularly prevalent in layers IV and V. Non-pyramidal neurons were categorized according to two features: (1) dendritic projection pattern, and (2) abundance of dendritic spines. Dendritic patterns were classified as multipolar, bitufted, and bipolar, and spine patterns as spinous, sparsely spinous, and spine-free. Spinous dendrites were associated only with multipolar neurons, while sparsely spinous and spine-free dendrites were each associated with cells of all three non-pyramidal dendritic patterns. The most frequently observed non-pyramidal cell types were multipolar cells of the spine-free and sparsely spinous varieties. All of the general cell types encountered have been described in the literature on non-pyramidal neurons, indicating the lack of any unique forms in rat area 17. An analysis of the dendritic projections of individual non-pyramidal neurons through particular cortical laminae made possible an evaluation of common sources of dendrites present in the neuropil of each layer. Non-pyramidal cell axons were impregnated only in small numbers. Spinous multipolar axons invariably exhibited a descending main branch, while the axons of bipolar neurons were distributed in a narrow vertical field. Axonal patterns of remaining cell types, including Golgi type II arborizations, did not appear to correlate consistently with dendritic morphology. Axons of the basket cell type and "horsetail" axons associated with double bouquet cells of Cajal's original type were not impregnated.

Animals↗
PubMed1978

Application of cell electrophoretic methods (preparative and analytical) in demonstrating the surface heterogeneity of T-lymphocytes in man.

The preparative electrophoretic method allows separation of several cell populations, which can be characterized by the usual membrane markers. This qualitative study shows a heterogeneous distribution of the T-lymphocytes from the most rapid to the slowest migration zones. The electrophoretic mobility (E.M.) of each fraction has been studied by analytical electrophoresis, which confirms the heterogeneity of T-cells. The experiments used total blood lymphocytes and rosette-forming cells with sheep red blood cells. The results obtained with the two methods were well correlated. The average migration speed of the separated populations showed a regular variation from one extreme fraction to the other. The E.M. speeds that characterize the main populations are--0.90 micrometer.sec.--1v.--1cm for the B-lymphocytes; for the T-lymphocytes,--1.10 (previously identified as the "low affinity" E-rosette FC),--1.20 and a small population centered around--1.35 (corresponding to active E rosette FC). In the T-lymphocytes separated after E-rosetting, the progresssive variation in the mean E.M. of each fraction is confirmed, as well as the existence of the previous 3 T-cell populations. Further studies have to be done, to show that each separated population does correspond with a functional differentiation.

Cell Membrane↗
PubMed1978

Antigenic activity and mobility of bovine pituitary hormones.

The antigenic activity and mobility of bovine pituitary hormones; follicle stimulating hormone (FSH), growth hormone (GH), luteinizing hormone (LH), thyroid stimulating hormone (TSH), adrenocorticotropic hormone (ACTH) and melanophore stimulating hormone (MSH) were studied with the aid of agar gel diffusion and electrophoresis. MSH and ACTH were the only hormones not demonstrating antigenicity. Tests by electrophoresis showed "gamma" mobility of the pituitary hormones exhibiting antigenic activity. The observation of antigenic determinants exhibiting identity with immunoglobulins suggests that the bovine pituitary gland houses immunoglobulin molecule and the various pituitary hormones.

Adrenocorticotropic Hormone↗
PubMed1977

A new procedure for examining Golgi impregnated neurons by light and electron microscopy.

A procedure is described by which neurons impregnated by the rapid Golgi method can be de-impregnated and their fine structure studied in the electron microscope, Brains are fixed by perfusion with buffered solutions containing formaldehyde and glutaraldehyde, and pieces are then impregnated by a rapid Golgi method. Sections, 150-200 micron thick, are cut from the impregnated blocks and immersed in glycerol so that sections containing suitably impregnated neurons can be selected under the light microscope. Such sections are immersed in gold chloride followed by oxalic acid. The original impregnation deposit of silver chromate is then removed with sodium thiosulphate. This process of de-impregnation leaves the originally impregnated neurons still visible in the light microscope for they now contain a deposit of gold. In the electron microscope this deposit is apparent as fine particles that mark the profiles of the de-impregnated neurons, but the deposit is such that it does not interfere with the fine structure which is remarkably well preserved. Thus, the cytological details of the de-impregnated neurons can be discerned and their synaptic relationships can be determined.

Animals↗