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Biomedical subjects

G Klein

Publications and source records attributed to G Klein.

At least 451 records · Page 25Linked to original sources
PubMed1990

Differential expression of laminin A and B chains during development of embryonic mouse organs.

Laminin is a large glycoprotein of basement membranes. The best described laminin from a mouse tumor contains three polypeptide chains (A, B1 and B2), but there is recent evidence that some cell types produce laminin isoforms lacking the A chain. We have here studied the occurrence of the isoforms during mouse organogenesis. In all tissues studied, the A chain mRNA and polypeptide were more weakly expressed than those of the B chains. Laminin A chain polypeptides showed a much more restricted tissue distribution than the B chains. Laminin A chain polypeptide was mainly detected in basement membranes of epithelial cells, suggesting that this chain is important for morphogenesis of epithelial sheets. Most endothelial basement membranes and all embryonic mesenchyme matrices studied seemed to lack the A chain even though they contained B chains. Several of the cells producing laminin devoid of A chain seem to produce other polypeptides that become complexed to the B chains. With an anti-laminin antiserum, which in immunoblots reacts only with A and B polypeptide chains, additional polypeptides of 160 and 190 x 10(3) Mr were co-precipitated from all tissues studied. In developing heart, a polypeptide of 300 x 10(3) Mr was co-precipitated in addition. Our data suggest that these laminin-associated polypeptides are not formed by a differential splicing of the known A chain mRNA. Northern blotting of poly (A)+ RNA showed only 10kb A chain transcripts but no truncated forms. We conclude that several cell types in the mouse embryo produce laminin variants that lack the 400 x 10(3) Mr A chain. Since a major cell binding site of laminin contains parts of the A chain, the variants should differ in biological function from laminin containing this A chain.

Animals↗
PubMed1990

[Molecular analysis of relationship between oncogene (N-myc and c-src) expression and major histocompatibility complex antigen gene expression in mouse neuroblastoma lines].

The authors have investigated the relationship between oncogene (N-myc and c-src) expression and major histocompatibility complex (H-2 in the mouse) antigen gene expression at the molecular levels, by using mouse neuroblastoma sublines (NB-1 and NB-V). Fluorescence-activated cell sorter analysis showed that NB-1 cells exhibited positive expression to H-2 Kk, H-2 Dd, and beta-2-microglobulin, while NB-V cells were negative to all three antigens. It was found that dimethyl sulfoxide (DMSO) had a capacity to increase an H-2 class I antigen expression on NB-1 cells, whereas no change was observed on NB-V cells after DMSO treatment. Molecular analysis with deoxyribonucleic and ribonucleic acid (RNA) blot hybridization and immunoprecipitation revealed that the enhancement of H-2 antigen expression on NB-1 cells was modulated at the transcriptional control of the H-2 gene. In contrast, negative H-2 antigen expression on NB-V cells was caused by block at the level of glycosylation of the H-2 heavy chain, although an increase in messenger RNA of the H-2 gene was induced after DMSO treatment. There was neither amplification nor rearrangement of N-myc and c-src oncogenes in either neuroblastoma subline. Nuclear run-on transcription assay revealed that the N-myc gene was post-transcriptionally down-modulated by DMSO, whereas the c-src gene was transcriptionally up-regulated. It was thus suspected that N-myc and c-src might be directly associated with cellular proliferation and differentiation in neuronal tumors and that in vivo tumorigenicity could be regulated by the control mechanism of oncogene expression in relation to H-2 gene expression on tumor cells.

Animals↗
PubMed1990

[Cytotoxic effector mechanism and genetic control of non-immunized hybrid resistance to mouse T cell lymphoma transplanted outside and inside the brain].

A Moloney virus-induced T cell lymphoma, YAC-1, derived from A/Sn (H-2a) inbred mouse origin, was tested for hybrid resistance (HyR) after subcutaneous (s.c.) or intracerebral (i.c.) tumor cell inoculation into syngeneic and semi-syngeneic mice. The F1 hybrids (H-2a/b) between A/Sn and C57BL/6 mice more strongly resisted the s.c. inoculation of 10(6) and 5 x 10(5) cells than did syngeneic recipients. In contrast, no HyR to the i.c. inoculation of 10(4) and 10(3) cells was seen in the F1 hybrid mice. Natural killer (NK) cell activity was much higher in F1 hybrids than in syngeneic mice. 125I-iododeoxyuridine-labeled YAC-1 cells were more efficiently eliminated from the highly resistant F1 hybrids than from the parental strain in both 4 and 18 hour in vivo rejection assays via intravenous (i.v.) and s.c. injection, respectively. The remaining radioactivity of the brain, however, did not differ between these mice. Thus, there was a correlation between the in vivo resistance of F1 hybrid mice to challenge s.c. inoculation of parental tumors and their expression of lymphocyte-mediated natural cytotoxicity in vitro against those tumors. T cell depletion by thymectomy followed by irradiation and fetal liver reconstitution did not abrogate the s.c. HyR against YAC-1, whereas NK cell depletion by i.v. administration of anti-asialo-GM1 antibodies resulted in the disappearance of the resistance. Furthermore, genotypic study segregating (A/Sn x C57BL/6) F1 x A/Sn backcross mice indicated that the s.c. HyR might be attributable primarily to heterozygosity within the H-2 complex.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Expression of the RB gene under the control of MuLV-LTR suppresses tumorigenicity of WERI-Rb-27 retinoblastoma cells in immunodefective mice.

Retinoblastomas arise by the loss of the retinoblastoma (RB) gene. The isolation of the RB gene and its expression in RB protein defective tumor cells permits direct tests of the ability of the protein to act as a tumor suppressor. We demonstrate that a functional RB gene introduced into WERI-Rb-27 retinoblastoma cells by retrovirally mediated gene transfer can suppress their tumorigenicity in immunodefective mice.

Animals↗
PubMed1990

Recombinant plasmid expressing the entire coding region of the Bmyc putative protein.

An expression vector with the entire coding region of Bmyc oncogene was constructed. The longest predicted open reading frame of Bmyc (178 amino acid residues) was expressed as a fusion protein with the trpE protein (308 amino acid residues) in transformed bacteria. The newly synthesized 58 Kd protein reacted with an anti pan-myc serum. The fusion protein isolated from a preparative Western blot was used as immunogen to generate rabbit anti myc specific immune sera.

Animals↗
PubMed1990

[Acute and long-term effects of chronic obstructive lung diseases].

In patients with chronic obstructive pulmonary diseases and cor pulmonale, long-term treatment with oxygen leads to a reduction in pulmonary arterial pressure. The aim of this study was investigate the question as to the extent to which pulmonary arterial pressure reduction in response to acute administration of oxygen differed from the long-term effect of oxygen treatment, and whether it was possible to determine prognostic factors that would identify the patients who would obtain particular benefit from long-term oxygen therapy. Twenty patients suffering from severe obstruction, global respiratory failure and precapillary hypertension, were treated with oxygen for a period of 20 +/- 6 months. At the beginning of the treatment, the acute oxygen-induced reversibility of pulmonary hypertension with an FIO2 of 80% was established. After an average of 20 months, catheter examination was repeated. A comparison was made between reversibility with acute oxygen and the long-term effects of oxygen. Long-term treatment with oxygen led to a reduction in pulmonary arterial pressure (18%), which was comparable to the reversibility established for acute oxygen inspiration (20%). While, over the long-term, a reduction in pulmonary arterial pressure was caused solely by a drop in pulmonary vessel resistance, acute application of oxygen resulted in an approximately equal decrease in pulmonary vessel resistance and cardiac output. The more pronounced the pulmonary hypertension prior to treatment the greater the pressure reduction achieved with long-term oxygen treatment. Patients with a particularly marked acute oxygen reversibility also had greater long-term benefit, in the sense that, in these cases, the decrease in pulmonary arterial pressure was more substantial than in patients with smaller acute reversibility.

Arrhythmias, Cardiac↗
PubMed1990

Influence of lornoxicam on serum pepsinogen levels.

Serum pepsinogen I was determined radioimmunologically in 18 patients suffering from lumbar backache syndromes. These patients were then treated with lornoxicam 4 mg twice daily over a period of 2 weeks. No significant increase in the serum pepsinogen I level was found in 17 (94.4%) of cases. Using the serum pepsinogen I as a parameter for the integrity of the gastric mucosa, this suggests good gastric tolerance of lornoxicam.

Adult↗
PubMed1990

The effect of myc proteins on SV40 replication in human lymphoid cells.

We have previously demonstrated that over-expression of c-myc facilitates the replication of SV40 DNA in human Burkitt lymphoma cells (BL). In this paper we investigated the ability of N-myc and L-myc to substitute for c-myc in promoting SV40 DNA replication. Vectors expressing either a chimeric N-myc/c-myc, N-myc or L-myc gene were constructed and co-transfected with a plasmid containing the SV40 origin of replication and the early genes encoding SV40 T antigens (Tag). The chimeric N-myc/c-myc and the N-myc proteins enhance SV40 replication in the human lymphoma line BJAB at levels comparable to c-myc. The stimulative effect of N-myc is also evident in the BL cell line RAMOS. However, L-myc stimulated SV40 replication only in RAMOS cells.

DNA Replication↗
PubMed1990

[Experimental analysis of anti-tumor cytotoxic mechanism for hybrid resistance to mouse neuroblastoma].

A spontaneous neuroblastoma (NB-85, H-2a/a) was tested for hybrid resistance (HyR) after subcutaneous (s.c.) inoculation into syngeneic and semisyngeneic mice. The hybrids (F1) (H-2a/b) between A/Sn and Leaden mice and the F1 between A/Sn X C57BL/6 mice were more resistant to the s.c. inocula of 10(6) to 5 X 10(5) cells than syngeneic recipients. Thymectomy, followed by irradiation and fetal liver reconstitution, abrogated the HyR against NB-85, whereas intravenous (i.v.) administration of anti-asialo-GM1 antibodies had no influence on the resistance. Surface phenotypic analysis revealed that NB-85 expressed H-2 Kk (-), Dd (+) and beta 2-microglobulin (-), showing a dissociation of the cell surface. Anti-H-2a-specific cytotoxic T lymphocytes exhibited a significant lytic activity against NB-85, while NB-85 was highly refractory to natural killer cell (NK)-mediated lysis. In vivo NK-mediated rejection assays showed that 125I-iododeoxyuridine (IUdR) labeled NB-85 cells were not eliminated more efficiently from the highly resistant F1 hybrids than from the parental strain. Furthermore, genotypic study with segregating (A/Sn X Leaden) F1 X A/Sn backcross mice showed that the HyR was attributable primarily to heterozygosity within the H-2 complex. Taken together, it was suggested that the HyR to an NK-resistant mouse NB-85 neuroblastoma might involve a T cell-dependent immunosurveillance with H-2 genetic control.

Animals↗
PubMed1990

Length of hospital stay in veteran surgical service patients with nosocomial infections.

Four hundred ninety-nine nosocomial infections (with 657 isolates) in 288 Surgical Service patients were monitored from February 1986 to June 1987 (17 months) to determine the influence that pathogen or site of infection had on the length of hospital stay. Patients with upper respiratory and skin infections were more likely to have significantly longer length of stay than those with infections in other sites. Infections with Haemophilus influenzae and Pseudomonas aeruginosa were more likely to yield longer culture to discharge periods than other organisms in certain settings. Extended lengths of stay were common in patients with nosocomial infections.

Cross Infection↗
PubMed1989

NK sensitivity and lung clearance of MHC-class-I-deficient cells within a heterogeneous fibrosarcoma.

The present study examines clonal variations in NK sensitivity in a methylcholanthrene-induced fibrosarcoma. Previous studies of clones from this tumor have shown considerable heterogeneity in H-2 expression, and an association between deleted or low levels of class-I products and increased tumorigenicity after subcutaneous implantation in immunocompetent syngeneic mice. Here, fibrosarcoma clones with no or low expression of MHC-class-I products were found to be sensitive to NK-mediated lysis, while clones with high levels of MHC-class-I expression were relatively resistant. One H-2+ (G2) and one H-2- (B9) clone were chosen for more detailed studies. Cold-target competition assays and conjugate cytotoxicity assays in agarose showed that splenic effector cells bound equally well to the H-2+ and H-2- tumor clone, although only the latter was sensitive to NK cell lysis. Treatment with 50 U/ml of rIFN-gamma for 48 hr increased the levels of H-2 expression and made both clones more resistant to NK-mediated lysis. In vivo studies with radiolabelled tumor cells showed that cells from the H-2+ clone survived better than cells from the H-2- clone in the pulmonary capillary bed after i.v. inoculation. This difference disappeared in mice treated with anti-asialo GM1 serum, known to deplete NK cell activity.

Animals↗
PubMed1989

Long-range restriction enzyme maps of DNF15S2, D3S2, and c-raf1 loci on the short arm of human chromosome 3.

Physical maps have been constructed around loci DNF15S2, D3S2, and c-raf1 on the short arm of human chromosome 3 using pulsed field gradient gel electrophoresis. The normal restriction pattern has not been altered by a t(3;8)(p14.2;q24.1) characteristic for a hereditary form of renal cell carcinoma, indicating that the breakpoint itself is not included in any of the mapped areas. We have found a CpG island within the DNF15S2 locus, suggesting the presence of a functional gene in the region.

Blotting, Southern↗
PubMed1989

Lysis of P3HR-1 cells induced to enter the viral cycle by antibody-dependent and independent immunological mechanisms.

The P3HR-1 Burkitt lymphoma line carries the Epstein-Barr virus (EBV) genome and a small proportion of the cells (1-3%) enter the lytic cycle spontaneously. Treatment with TPA and n-butyrate elevates considerably the number of virus-producing cells (25-35%). Cells which enter the lytic cycle express the EBV early antigen EA, the viral capsid antigen VCA, and the membrane antigen MA. Antibodies against these antigens are present in EBV-immune human sera. The expression of virus envelope protein on the plasma membrane renders the cells sensitive to immune effector mechanisms. These were shown to be initiated by the alternative complement pathway (ACP)-activating capacity of the cells and by their reactivity with antibodies directed to the MA. When incubated with EBV-immune or nonimmune human serum, the induced (P3HR-1-V) cells activated C3 through ACP and fixed the generated C3 fragments. The efficiency of opsonization was higher in immune serum. By varying the experimental conditions we showed the damage of the induced cells by the complement system and by blood lymphocytes, and analysed the involvement of antibodies and the activated C3 fragments in the lymphocyte-mediated lysis. P3HR-1-V cells were lysed by immune serum and also by nonimmune serum though with lower efficiency. The induced cells had elevated sensitivity to the NK effect which was potentiated if the conditions allowed their opsonization. In the presence of antibodies the lymphocyte-mediated lysis was considerably higher and the ADCC mechanism was also potentiated by opsonization. These experiments suggest that B cells which enter the virus-producing cycle may be eliminated in EBV nonimmune host by NK cells. After the antibody response against the virus develops, the attack on these cells is more efficient through complement and lymphocyte-mediated antibody-dependent mechanisms. These effector mechanisms are enhanced by opsonization which is the consequence of the C3-activating capacity of the cells. The multiple ways of the immune attack on the B cells prepared to produce EBV may explain the absence of EA and VCA positive B cells in tumor cell populations and during the acute phase of infectious mononucleosis.

Antibodies, Monoclonal↗
PubMed1989

Efficient retroviral transfer of a mouse c-myc construct into HL60.

We introduced an LTR-driven mouse c-myc second and third exon, Tn5Neo gene construct into the inducible human leukemia line HL60 using an amphotropic retroviral vector system. Over 90% of the cells became neo-resistant and the transfected myc gene was transcribed in several neomycin resistant clones. Making use of the simultaneous presence of the different myc genes in the same cell, we compared expression of the corresponding mRNAs after differentiation and their decay mechanisms.

Animals↗