PubMed Health⌕ Search

Biomedical subjects

A Raedler

Publications and source records attributed to A Raedler.

90 records · Page 5Linked to original sources
PubMed1982

Differences of glycoconjugates exposed on hypernephroma and normal kidney cells.

We analyzed the outer cell membranes of normal kidney cells, hypernephroma cells, nude mouse transplants of hypernephroma tissue, and cell lines derived from hypernephroma using horseradish peroxidase-coupled lectins of different specificity, in order to investigate their binding to cryostat sections or the cell surfaces of suspended single cells. We showed that hypernephroma cells express higher amounts of receptors for Robinia pseudoacacia lectin, soy bean lectin and Phaseolus vulgaris lectin compared to those prepared from normal kidneys. In contrast, Helix pomatia lectin is bound to connective tissue elements of both malignant and non-malignant tissue exclusively. L-fucose and D-galactose residues are detectable on malignant cells, but not on their non-malignant counterparts. However, the expression of the latter varies considerably among cells from different hypernephromas. No significant difference could be demonstrated between hypernephroma, hypernephroma cell lines and hypernephroma transplants in regard to the carbohydrate profile on the cell surfaces.

Acetylgalactosamine↗
PubMed1982

[Are Crohn disease and ulcerative colitis the results of an immunoregulatory disturbance?].

The increasing knowledge regarding the regulation of immunological processes has stimulated different approaches to the analysis of chronic inflammatory bowel diseases. The well documented independence of the mucosa-associated immune system favours data obtained analysing immunological reactions within the mucosa. Thus lymphocytes and antibodies isolated from the mucosa are consequently used instead of those obtained from peripheral blood. Despite of an initiation by exogenic agents such as allergenic food constituents for microorganisms there is a growing body of evidence pointing to an immunoregulatory disturbance as underlying pathogenic mechanism for these diseases. This hypothesis is discussed regarding recent observations of a contrasuppressive circuit of regulatory lymphocytes in the murine intestine.

Animals↗
PubMed1982

Subcapsular thymic lymphoblasts expose receptors for soy bean lectin.

In the course of analysing thymic cellular constituents concerning the expression of lectin receptors and defined lymphocyte differentiation antigens, respectively, a subpopulation of thymic lymphocytes was detected exposing both peanut lectin (PNL) and soy bean lectin (SBL) receptors on their surfaces, while the majority of cortical thymic lymphocytes were found to be PNL positive, but SBL negative. This subset of SBL+PNL+thymic lymphocytes in the adult populates the area beneath the thymic capsule, forming a narrow rim only, while in perinatal thymus a corresponding subcapsular cell layer comprises almost one third of the thymic tissue and in early ontogenesis the vast majority of thymic lymphoid cells are PNL+SBL+. By ultrastructural analysis of double labelled cell suspensions as well as of cells separated by affinity chromatography, it could be shown that PNL/SBL+ cells frequently exhibit morphological features of lymphoblastic cells. Thus this subcapsularly located subset seems to represent a compartment of proliferating immature cells, descended from bone marrow and foetal liver prethymic cells, respectively, and giving rise to PNL/SBL- cortical thymic lymphocytes.

Animals↗
PubMed1981

Studies on the nature and cellular distribution of TLMA--a major rat T axis differentiation antigen. Identification as the glycosphingolipid GgOse4Cer (asialo GM1).

The recently detected T axis differentiation antigen, which was provisionally designated as T-lymphocyte-macrophage-associated antigen (TLMA) could now be identified as the neutral glycosphingolipid GgOse4Cer (asialo-GM1). TLMA is not only expressed on lymphocytes on the T lineage and on macrophages of the rat, but also on eosinophilic cells. On erythrocytes, the determinants are only detectable after neuraminidase treatment. Within the cell surface of thymic lymphocytes, the antigen determinant is partly masked by sialic acid residues. Presently, it cannot be decided whether the masking effect is brought about by sialic acid residues of adjacent glycolipid molecules or whether a nonreactive sialylated precursor molecule exists.

Absorption↗
PubMed1981

Terminal galactosyl residues of cell-surface glycoconjugates exposed on both human and murine immature T- and B-cells.

Exposure of terminal galactosyl residues on cell-surface molecules as detected by their ability to bind peanut lectin (PNL) is found to be characteristic for immature cortical human and murine thymic lymphocytes. While in prenatal mice PNL staining is found to be uniformly distributed among all thymic lymphocytes, in adult thymic a cortico-medullary gradient is detectable concerning the PNL-binding capacity of thymic cortical lymphocytes, a phenomenon that appears to be correlated to their maturational degree. In secondary lymphatic tissue, i.e. lymph nodes and spleen of man, mouse and rat, strongly labeled cells are found exclusively in germinal centers. Ultrastructurally, these cells could be identified as centrocytes and centroblasts. These observations suggest that exposed galactosyl moieties of cell-surface glycoconjugates are expressed by undifferentiated lymphocytes of both T- and B-cell lineage. Furthermore, it could be shown that PNL-binding properties of immature cells are not restricted to lymphatic tissue but can also be demonstrated on various embryonic cells of non-lymphatic origin in distinct developmental stages. Thus, they might have a fundamental significance in the course of maturation processes.

Animals↗
PubMed1981

Varying expressions of lectin receptors within embryonic cell layers of murine cerebral cortex.

The ability of prenatal cerebral tissue to bind different lectins was analyzed using cryostat sections of mouse brains. It was shown that the immature cells within the embryonic cell layers possess receptors for different lectins in varying amounts. Of all lectins tested, only PNL, RCL and LPL were bound on the outer cell membranes to a considerable degree. Although the labeling patterns of PNL and RCL are similar, the latter is additionally well detectable on the wall of cerebral blood vessels. Cells of the ventricular layer are moderately labeled by PNL, which recognizes beta-D-galactosyl (1-3)-N-acetyl-D-galactosamine, but heavily labeled by LPL which binds to terminal sialic acid residues. Cells of the intermediate layer, on the other hand, are heavily stained PNL and only faintly by LPL. Hence it is suggested that the process of migration might be correlated to the removal of terminal sialic acid moieties from cell surface glycoconjugates, resulting in an exposure of the penultimate galactosyl residues.

Animals↗
PubMed1981

Prenatal differentiation of colliculus superior in the rat.

Up till emybryonic day (ED) the 13 the prenatal histogenesis of rat mesencephalic roof is characterized by an exclusive proliferation of ventricular cells. Then the first differentiating postmitotic cells are found above the ventricular layer, so that proliferation and differentiation occur simultaneously. On ED 15 a lamination typical for embyronic CNS with ventricular, subventricular, intermediate layers and stratum zonale can be observed in the area of presumptive colliculus superior. A definite demarcation between ventricular and subventricular layers, however, is only possible by means of autoradiograpahic methods. At the end of gestation the lamination of adult colliculus superior is already noticeable. During early prenatal development, cells which originate on one single day can autoradiographically be demonstrated in different cell layers and particularly over the whole width of the intermediate layer, while towards the end of gestation time of cell origin and location inside the mesencephalic roofs are closely correlated: cells that originate on ED 13 can be found predominantly in deeper cell layers (stratum griseum profundum, lower stratum griseum intermedium), while cells originating on EDs 15 and 17 are on ED 21 situated in the upper cell layers (upper stratum griseum intermedium, stratum griseum superficiale). This results in an inside-outside gradient of cell origin, which corresponds to an inside-outside gradient of cell differentiation. Besides, a rostro-caudal and a lateromedial gradient can be observed. On ED 13 a median ventriculaar formation (MVF) can be distinguished displaying a significantly lower mitotic activity than the cells of the neighbouring ventricular layer as could be demonstrated by autoradiographic investigation. This difference is even more pronounced in latter embryonic stages. From ED 17 on the cells of this particular structure are arranged in a typical onion-like pattern. Towards the end of gestation the MVF expands considerably as compared with the surrounding ventricular layer. As long-time experiments with 3H-thymidine reveala this increase in area is brought about by the immigration of numerous ventricular cells which originated on earlier embryonic days. The apical processes of the cells of the MVF form a thick fibre bundle which can be followed upwards to the stratum zonale. Ulstructurally these strictly parallel arranged fibers mainly resembly astroglial processes, but possess, in contrast to the latter, numerous microtubules. Because of their morphological characteristics a classification of these cells as tanycytes appears justified. The MVF is compared with similar structures in other regions of the CNS and its possible function as a guide for migrating preneurons is discussed.

Animals↗
PubMed1979

Evidence for the expression of Thy-l-analogous structures on human thymic epithelial cells.

Cultured human thymic tissue was examined electron microscopically and analysed for the expression of the Thy-l-analogous antigen. It was found that almost all cultured cells were of epithelial appearance, exhibiting both tonofibrils and well-developed demosomes. Absorption of an anti-human brain serum highly purified for antibodies directed against the non-species-specific determinant of the Thy-l-analogous antigen with these cultured cells revealed its presence on thymic epithelial cells. Using the indirect peroxidase-labelled antibody technique, this molecule could be localized on the non-attached cell surface of human thymic epithelial cells with the preference of their cell processes. The biological significance of the expression of this antigen on the thymic epithelial cells of various species for cellular interaction within the thymus is discussed.

Cell Membrane↗
PubMed1978

Autoradiographic study of early neurogenesis in rat neocortex.

The early neurogenesis of rat neocortex was analysed by means of light and electron microscopic autoradiography. It was found that the very first preneurons originate probably as early as ED 11. They are the horizontal cells of Cajal-Retzius. The peak of their formation is on ED 13 (surface index estimated on ED 17 after injection of 3H-thymidine on ED 13:21, after injection on ED 12:4, after injection on ED 15:5), WHereas no Cajal-Retzius cells could be found to have originated after ED 15. Theses cells are the developmentally most advanced of the neocortex. The cells second in date of origin and maturation are preneurons which presumably correspond to the presumptive neurons of Layer VII (VI b), and begin to originate on ED 12. The end of their formation could not be defined owing to a lack of ultrastructural differences to other, younger preneurons in later gestational stages. These two cell types are the first cellular components of the primordial plexiform layer (Marin-Padilla, 1978) or pallial anlage (Rickmann, 1977), demonstrating an outside-in gradient within this layer, and are separated by the formation of the cortical plate. This could be proven by their simultaneous labelling above and below the cortical plate after administration of 3H-thymidine before ED 15. These results confirm the hypothesis of a dual origin of the mammalian neocortex (Marin-Padilla, 1978).

Animals↗
PubMed1978

Evidence for the presence of Thy-1 on cultured thymic epithelial cells of mice and rats.

Thymic tissue of C57BL/6 mice and DA rats was cultured. After 6--8 weeks, cultures were analyzed for their capacity to absorb anti-Thy-1 serum, and for the expression of Thy-1 on the surface of different cell types by means of the indirect peroxidase labeling method. Three main cell types were identified: epithelium-like cells, fibrocyte-like cells and macrophages, but no lymphocytes were found. The presence of Thy-1 on cultured nonlymphocytic thymus-derived cells was demonstrated by their ability to absorb the cytotoxic activity of the appropriate anti-Thy-1 sera. Electron microscopical analyses of labeling experiments revealed that Thy-1 was predominantly expressed on epithelium-like cells with preference for their cell protrusions. The possible role of Thy-1 expression, both on thymocytes and thymus epithelium for cellular interaction, is discussed.

Animals↗
PubMedDate not supplied

N alpha-carboxyacyl analogues of CCK with a substituted Gly: interaction with pancreatic and gallbladder CCK receptors.

It has been reported that certain N alpha-carboxyacyl analogues of CCK-8 and of CCK-7 with a substituted Gly in position 3 or 4 of the peptide possess higher potencies at stimulating pancreatic enzyme secretion than at stimulating gallbladder contraction, suggesting that these analogues are able to differentiate subtypes of CCKA receptors. However, no studies examined directly the interaction of these peptides with the CCK receptors in both tissues. In the present study, CCK-8 and various N alpha-carboxyacyl analogues of CCK-7 and of CCK-8 were prepared by solid phase synthesis using Fmoc chemistry and were purified by HPLC; molecular weight and sufficient sulfation were determined by mass spectrometry. [125I]Bolton-Hunter(BH)-CCK-8 binding to sections of the guinea pig pancreas and gallbladder was determined under identical conditions; amylase release from pancreatic acini and contraction of gallbladder muscle strips were measured in vitro. Each peptide stimulated amylase release (EC50): CCK-8 (0.09 nM) > Suc[Sar3]CCK-7 (0.23 nM) > des(SO3)CCK-8 (28 nM) > Suc[D-Trp4]CCK-8 (32 nM) > Suc[D-Trp3]CCK-7 (53 nM) > Pht[D-Trp3]CCK-7 (180 nM) > Glt[D-Trp3]CCK-7 (220 nM). The same relative potencies were found for stimulation of gallbladder contraction, and for the inhibition of [125I]BH-CCK-8 binding to pancreas and gallbladder sections. These data demonstrate that the CCKA receptors in the pancreas and on gallbladder smooth muscle possess similar affinities for the various N alpha-carboxyacyl analogues of CCK-7 and CCK-8 with a substituted Gly and provide further evidence that the CCKA receptors in gallbladder and pancreas cannot be distinguished pharmacologically.

Amylases↗