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Biomedical subjects

G Schumann

Publications and source records attributed to G Schumann.

At least 127 records · Page 7Linked to original sources
PubMed1978

Immunosuppressive activity of antibody directed against endogenous C-type virus interferes with early events of the immune response.

We have analyzed the effects of an antiserum prepared against BALB/c endogenous xenotropic C-type virus on the humoral immune response of mice. Both in vivo and in vitro, this serum suppresses the response to sheep red blood cells, an effect that can be absorbed out by purified BALB/c xenotropic C-type virus or Friend leukemia virus, but not by Rous sarcoma virus. The serum produces its maximum effect when administered together with or before the antigen, but not 24 hr later. This suggests that it acts on an early event of the immune response. Evidence is presented to show that the critical viral antigen is expressed before the spleen cells are experimentally stimulated by antigen. The same immunosuppressive effect was observed in a variety of mouse strains, including the high-leukemia incidence AKR strain and virus-free 129/J mice, indicating that it is independent of the expression of endogenous virus. The finding that a viral antigen is involved in the transition from a resting to a dividing lymphocyte is discussed with respect to viral involvement in leukemia.

Animals↗
PubMed1978

[Insulin and pro-insulin secretion following intravenous administration of tolbutamide, glisoxepide and glibenclamide].

12 metabolically healthy subjects were i.v. administered equipotent doses (ED30) of tolbutamide (7.5 mg/kg), glisoxepide (0.02 mg/kg) and glibenclamide (0.006 mg/kg). Prior to and 2, 5, 8, 10, 20, 40, 60 and 120 min after the injection the following serum parameters were determined: blood glucose, immunologically measurable insulin (IMI) with the double-antibody method (Hales and Randle) and proinsulin (IMP) enzymatically (ISP-method). The maximum level of insulin follows the injection of tolbutamide with a value of 70.5 micronU/ml after 2 min, of glisoxepide after 5 min (67.0 micronU/ml) and of glibenclamide after 20 min (32.3 micronU/ml). The proinsulin fraction of the total insulin shows a level of 12.5 micronU/ml before the test. After the administration of the three compounds proinsulin increases, too, but reaches only 20-40% of the total immunoreactive insulin. The amount of secreted insulin and proinsulin during the 120-min test is rather the same for the three substances. The average increase of insulin is nearly identical for tolbutamide and glisoxepide, whereas it is less for glibenclamide. Both the mean blood sugar depression and the highest mean increase of proinsulin is reached after glisoxepide. The significance of the one-chain precursor of insulin as a part of the sulfonylurea stimulated total insulin for glucose depression is discussed.

Blood Glucose↗
PubMed1978

[Frequency of diabetes mellitus and nature of treatment in urologic diseases].

In a comparative period of 20 years is reported on the frequency of diabetes mellitus in urological diseases. It was found that 0.87% of the patients suffer from a concomitant diabetes. The peak of the disease is between the 60th and 70th year. As to the distribution of sex was established that the concomitant diabetes is to be found more frequently in males (ratio 2.4: 1). The lethality in diabetics with a urological disease is with 9.4% more than twice as high as in the other urological patients (4.3%). At the top of the immediate causes of death is the cardiovascular failure (30.7%), followed by the pulmonary blood clot embolism and the uraemic coma with 15.4% each. A diabetic coma never appeared. In the analysis of the urological diseases with concomitant diabetes the lithiasis (34.4%) is in the first place; then follow the adenoma of the vesical cervix (32.4%), the chronic relapsing pyelonephritis (12.9%), and the malignant tumours (7.1%). Many urological forms of diseases appeared combined. In the investigation of the complications without lethal exitus which appeared in 25.1% of all cases with concomitant diabetes the cardiovascular failure is again in the first place, then follow thrombotic diseases, urea-nitrogen disturbances. Peculiarities in conduction and treatment of the diabetes mellitus are shown and a close collaboration between several specialities is considered necessary.

Adult↗
PubMed1978

[Inhibition of rat liver delta 4-3-ketosteroid-5 alpha-reductase by steroids in vitro].

The inhibition of the hydrogenation of testerone to 5alpha-dihydrotestosterone in microsomes of female rat liver has been studied by progesterone-, testosterone- and estradiol derivatives. In the pregnane series, progesterone, 17alpha-OH-progesterone and its acetate were the strongest inhibitors. In the estradiol series, 3-hydroxy-compounds with a CH2X-substituent at 17alpha-position were stronger inhibitors than the respective 3-methoxy derivatives. The most potent inhibitor till now is an estradiol derivative with a SeCN group in 16alpha-position.

5-alpha Reductase Inhibitors↗
PubMed1976

Mitogen induction of murine C-type viruses. I. Analysis of lymphoid cell subpopulations.

We reported previously in vitro induction of endogenous C-type viruses from normal mouse spleen cells by lipopolysaccharide (LPS) as well as by combination treatment with concanabalin A and 5-bromo-2'-deoxyuridine (Con A/BrdU). To identify the cell types sensitive to virus induction and to study the relationship of mitogenicity to virus induction we have compared T cell populations (BALB/c thymus cells and cortisone-resistant thymus cells), B cell populations (nu/nu spleen cells and lymph node cells), adherent BALB/c peritoneal cells and mixed populations (BALB/c spleen cells, macrophage-depleted BALB/c spleen cells, and lymph node cells). LPS-induction occurred only in B cell-containing populations. In contrast, induction by Con A/BrdU depended on the presence of both T and B cells. In both instances, neither macrophages nor hemopoietic cells appeared to be a major source of virus. Treatment with anti-Ig serum and complement reduced virus induction by LPS/BrdU but not by Con A/BrdU suggesting that different cell populations produce virus after stimulation with these two different mitogens.

Animals↗
PubMed1975

Induction of endogenous murine C-type virus in spleen cell cultures treated with mitogens and 5-bromo-2'-deoxyuridine.

In short-term cultures of BALB/c spleen cells, treatment with a combination of 5-bromo-2'-deoxyuridine (BrdU) and either lipopolysaccharide W. Escherichia coli or concanavalin A resulted in release of C-type virus into the medium. Only lipopolysaccharide induced virus release when given alone. This could be potentiated by a combined treatment with BrdU. In contrast, phytohemagglutinin at mitogenic concentration had no effect with or without BrdU, suggesting that inducibility may vary between various mitogen-responsive spleen cell populations. In AKR mice, spontaneous virus release was detectable in nonstimulated spleen cell cultures. This could be potentiated by lipopolysaccharide, whereas no further increase occurred upon additional BrdU treatment. The induced viruses had C-type characteristics in that they contained reverse transcriptase that could be distinguished from cellular enzymes by template-primer preference experiments. Furthermore, the enzyme activities were particle-associated, banding in isopycnic sucrose gradients at 1.15-1.17 g/cm-3. The presence of C-type viruses was confirmed by electron microscopy.

Animals↗
PubMed1974

Complement-dependent B-cell activation by cobra venom factor and other mitogens?

It has been proposed that two distinct signals are required for the triggering of the precursors of antibody-forming bone marrow-derived cells (B cells): (a) the binding of antigen or of a mitogen to the corresponding receptor sites on B-cell membranes and (b) the interaction of activated C3 with the C3 receptor of B lymphocytes. There is growing evidence that B-cell mitogens and T (thymus-derived cell)-independent antigens are capable of activating the alternate pathway of the complement system (bypass). Therefore, the effect of another potent bypass inducer was investigated with regard to B-cell activation and the role of C3. Purified, pyrogen-free cobra venom factor was mitogenic for both T and B lymphocytes (cortisone-resistant mouse thymus cells and lymph node lymphocytes from congenitally athymic mice). Venom factor could substitute for T cells by restoring the potential of antibody formation to sheep red blood cells in mouse B-cell cultures supplemented with macrophages or 2-mercaptoethanol. Venom factor may be capable of conferring activated C3 to the C3 receptor of B lymphocytes: preincubation of lymphoid cells with homologous serum or plasma, 10 mM EDTA, and sepharose-coupled venom factor converted with serum to an enzyme active against C3, inhibited their capacity to subsequently form rosettes with sheep erythrocytes sensitized with amboceptor and C5-deficient mouse complement. In the absence of EDTA, preincubation of freshly prepared B-cell suspensions with C3-sufficient homologous serum also blocked their subsequent interaction with complement-sensitized erythrocytes and at the same time rendered them reactive to an otherwise T-cell-specific mitogen. Moreover, mitogen induced B-cell proliferation in lymph node (but not in spleen) cell cultures, appeared to depend on the availability of exogenous C3: zymosan-absorbed fetal bovine serum (only 8.3% site-forming units remaining) supported T-cell activation by phytohemagglutinin, concanavalin A, and venom factor, but failed to sustain B-cell stimulation by pokeweed mitogen, lipopolysaccharide, and venom factor. T-cell-dependent antibody formation in composite cultures containing T cells or T-cell-substituting B-cell mitogens, B cells, and macrophages, always required the presence of C3-sufficient serum.

Animals↗