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Biomedical subjects

R Arndt

Publications and source records attributed to R Arndt.

At least 109 records · Page 6Linked to original sources
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

Pancreatic oncofetal antigen in pancreatic juices. Partial chemical characterization and diagnostic application of a pancreatic cancer-associated antigen.

Antisera were raised in rabbits to an antigenic structure present in fetal pancreas tissue, pancreatic tumor tissue, and pancreatic juices and in sera obtained from pancreatic cancer patients. The first chemical data indicate that this pancreatic oncofetal antigen is distinct from CEA, NCA, and NCA2 and is not glycolipid in nature. Immunoelectrophoretic analyses demonstrate that pancreatic oncofetal antigen is a protein or a glycoprotein, which displays microheterogeneity. The apparent molecular weight of the basic unit of pancreatic oncofetal antigen is estimated to about 40 K. So far 234 pancreatic juices have been investigated for pancreatic oncofetal antigen. Pancreatic oncofetal antigen was detected within the pancreatic juices from 59 of 74 (80%) pancreatic carcinoma patients but could be traced in only 16%-26% of samples obtained from patients with other diseases.

Adult↗
PubMed1980

Isolation and characterization of the thymus-brain antigen (analogous to thy-1 antigen) from human brain.

1. The human thymus-brain antigen, which corresponds to the murine (mouse or rat) Thy-1 antigen complex, was isolated from brain after solubilization in deoxycholate by gel-permeation chromatography, wheat-germ-lectin affinity chromatography and ion-exchange chromatography. 2. The isolated antigen is a glycoprotein displaying an apparent molecular weight of 26 000-29 000 in sodium dodecyl sulphate/polyacrylamide-gel electrophoresis. 3. No antigen activity was found with the lipid fraction from human brain. 4. The protein has a tendency for spontaneous self-association (dimerization), leading to aggregates resistant to dissociating and reducing agents on prolonged storage. 5. The antigen is microheterogeneous with respect to size, charge (approximate isoelectric points of the monomer 7.7, 7.0 and 6.5) and to lectin-binding affinity. 6. The antigen can be reconstituted to protein-lipid vesicles. The antigen activity of solubilized antigen is strongly increased by reconstitution and that of membranes decreased by solubilization with detergent.

Antigens↗
PubMed1980

Gangliotetraosyl-ceramide, the rat T lymphocyte-macrophage-associated antigen: chemical detection and cellular distribution.

The presence of gangliotetraosyl-ceramide, i.e., Gal beta 1 leads to 3GalNAc beta 1 leads to 4Gal beta 1 leads to 4Glc beta 1 leads to Cer, the T lymphocyte-macrophage-associated antigen, on lymph node cells, thymic lymphocytes, and peritoneal exudate cells of the rat was established. For this, the glycosphingo-lipids of the cells were extracted and isolated by a microseparation and detection method. In contrast to immunoglobulin-negative rat lymph node cells, immunoglobulin-bearing lymph node cells showed no detectable gangliotetraosyl-ceramide.

Animals↗
PubMed1979

Detection and partial characterization of a new murine T-lineage antigen: evidence for its enzymatic modulation.

A molecule with an apparent molecular weight of 21,000 daltons was found to be a predominating differentiation antigen of peripheral rat T lymphocytes. This antigen is also expressed on the cell surface of thymus lymphocytes though partially in masked form. The observation that these determinants could be unmasked by neuraminidase treatment in vitro suggests that enzymatic processes may play an important role in antigenic transformation along the differentiation pathway of T axis lymphocytes. Since this structure was found to be displayed also by peritoneal exudate macrophages, it is referred to as T lymphocyte-macrophage antigen. The finding that an identical antigen could be identified in the mouse suggests its more common biological significance.

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↗
PubMed1979

[Common ALL-associated antigen on cells and in the serum of common ALL patients: clinical relevance and biochemical characterization (author's transl)].

The clinical application of an antiserum recognizing common ALL associated antigen (cALL-AG) is very useful in classifying leukemias and diagnosing bone marrow relapse as well as CNS-leukemia. We could demonstrate that sera of common ALL (cALL) patients contain cALL-AG; its partial biochemical characterization is described. The anti cALL serum (cALL-AS) was raised in rabbits with cALL-cells precoated with rabbit antiserum against normal human lymphocytes. After appropriate absorbtion the cALL-AS was highly specific for cALL cells. The isolation of serum cALL-AG was performed by ammoniumsulfat precipitation, gel chromatography and affinity chromatography on agarose lens culinaris hemagglutinin A (lentil lectin). The apparent molecular-weight of the serum glycoprotein is 125 000. Two cALL-AG active structures could be solubilized from cALL cell membrane. The apparent molecular-weights were calculated to be 55 000 and 110 000.

Antigens, Neoplasm↗
PubMed1979

[Electroencephalographic problems in newborn infants].

The authors present the results of electroencephalographic examinations performed at random in a group of 100 newborn "risk infants". Ordinary electroencephalograms were compared with those obtained by long-time polygraphic recording. It was found that ordinary electroencephalography was quite acceptable for the basic diagnosis of neurological diseases. The number of pathological curves on the electroencephalograms after the polygraphic recording was not greater than on ordinary encephalograms.

Birth Injuries↗
PubMed1979

[Treatment of epilepsy with clonazepam (Antelepsin)].

Clonazepam (Antelepsin) was tested on 179 patients in 8 institutions during a period of 180 days. 169 patients had been unsuccessfully treated with the usual standard medication and were additionally given Antelepsin. Typical absences and attacks of the West and Lennox syndromes yielded best to treatment with the drug, with favorable effects also being produced in cases of partial or focal epilepsy. The most important side-effect was tiredness, other collateral effects being balance disorders, sensations of dizziness, and musuclar weakness. The frequency of side-effects decreased in the course of therapy. In the electroencephalogram there was observed a significant increase in beta waves and a significant decrease in 3 Hz spike and wave complexes.

Benzodiazepinones↗
PubMed1978

Chromatographic study on the specificity of bis-p-nitrophenylphosphate in vivo. Identification of labelled proteins of rat liver after intravenous injection of bis-p-nitro[14C]phenylphosphate as carboxylesterases and amidases.

The procedure established to isolate the carboxylesterases E1, E2 and EA from rat liver (Arndt, R. and Krisch, K. (1972) Hoppe-Seyler's Z. Physiol. Chem. 353, 589-598) was applied to characterize in vivo bis-p-nitro[14C]-phenyl-P-labelled proteins. The peaks of radioactivity and of residual enzyme activities (hydrolysing methylbutyrate, p-nitrophenylacetate and acetanilide) were found in the same peaks after column chromatography and could be related to the well-defined esterases E1, E2 and EA. There is no indication of a nonspecific binding of bis-p-nitrophenyl-P or of one of its metabolites. The relative quantitative amounts of E1, E2 and EA were calculated to represent 40, 14 and 46%, respectively, of the total carboxylesterase content of rat liver. The relative amount of bound (not dialysable) radioactivity in rat liver depended on the survival time. During purification, the yield of enzyme activities corresponded to that of bound radioactivity, confirming the specificity of bis-p-nitrophenyl-P in vivo. Hence the radioactive metabolites of the inhibitor obviously do not possess binding affinities of quantitative importance to the rat liver proteins.

Amidohydrolases↗