Biomedical subjects

I Markus

Publications and source records attributed to I Markus.

4 recordsLinked to original sources

PubMed1995

Measurement of growth hormone-binding protein in the rat by a ligand immunofunctional assay.

We have developed a ligand immunofunctional assay (LIFA) for quantifying the circulating functional GH-binding protein (GHBP) in the rat. This two-site solid-phase assay uses a capture monoclonal antibody (4.3) specific to the hydrophilic C-terminal segment of rat GHBP (rGHBP), saturation of binding with human GH, and a detection system of rabbit antihuman GH polyclonal antibody and peroxidase-conjugated antirabbit immunoglobulin G antibody. Results were compared with Scatchard estimates derived by immuno-precipitation with monoclonal antibody 4.3. This assay was used to determine the GHBP levels in male and female rats and to investigate the diurnal properties and dynamics of GH and GHBP interaction in 15-min blood sampling over a 6-h period. The dynamic range of the rLIFA was 0.15-20.0 nM recombinant rGHBP, with intraassay and interassay coefficients of variation of 10.5% (n = 20) and 12.9% (n = 12), respectively. Serum GHBP levels determined by the rLIFA and those derived from Scatchard estimates were strongly correlated (n = 8; beta = 0.55; r2 = 0.89; P = 0.0005). Male rats had lower GHBP levels (6.5 +/- 0.7 nM; mean +/- SE; n = 14) than female rats (35.4 +/- 2.7 nM; n = 15; P = 0.0001). In the diurnal study, male rats had higher GH peaks (312.5 +/- 121.6 ng/ml; n = 7) than female rats (96.5 +/- 15.4 ng/ml; n = 9; P < 0.0001). In contrast to the pulsatile secretion of GH, GHBP levels in both sexes remained stable and showed no relationship to secretory pulses of GH. However, the GH bursts significantly altered the distribution of the GH-GHBP complex in male rats. By saturation and mass analysis, the greater GH pulsatile secretion in male rats resulted in occupancy of GHBP from less than 5% at nadir to about 80% at secretory peaks, in contrast to the less than 5-15% range of GHBP occupancy in female rats. In male rats, greater than 80% of GH at secretory peaks existed in the free form, whereas in female rats, 16-23% of GH existed in the free form during pulsatile secretion. In summary, the rLIFA shows good correlation to Scatchard analysis using an identical antibody. We conclude that this assay provides a rapid, sensitive, and accurate measurement of the circulating functional GHBP in the rat, and that it facilitates the study of GH and GHBP dynamics under a range of physiological conditions.

Animals↗

PubMed1993

Diethylnitrosamine- and partial hepatectomy-induced decrease in alpha 2u-globulin mRNA level in the rat liver.

Changes in gene expression in the rat liver were investigated by analyzing cDNA libraries for liver mRNAs from adult male rats injected with a chemical carcinogen diethylnitrosamine (DEN). Differential screening using normal and DEN-treated liver cDNAs as probes demonstrated that some of the mRNA species had noticeably lower abundance in the DEN-treated liver than in the untreated liver. Surprisingly, most of those clones were found to code for alpha 2u-globulin (A2uG), an abundant protein in the male rat liver. Further analysis by in situ hybridization revealed that the decrease in the A2uG mRNA level occurred in the area where liver cells were proliferating due to DEN treatment and/or partial hepatectomy (PH). The findings indicate coincidence of cell proliferation with a decrease in the A2uG gene expression in the adult male rat liver, implying that the A2uG-related change favors chemical carcinogen-induced cell growth.

Alpha-Globulins↗

PubMed1990

Enhanced invasiveness and metastatic potential of epithelial cell lines cultured in the presence of dimethyl sulphoxide.

Several passage cycles of poorly metastatic malignant epithelial cells through immunosuppressed mice failed to induce enhanced metastasis-forming ability of cells derived from either the primary subcutaneous tumours or the resultant lung metastases. In vitro treatment of cultured malignant cells with dimethyl sulphoxide (DMSO) induced a reversible change in phenotype towards increased invasiveness but did not significantly increase metastasis formation. A cloned-cell line from a spontaneous in vitro transformant in the presence of DMSO was highly invasive and highly metastatic. In vitro treatment of cultured cells with 2% (v/v) DMSO produced alterations in morphology with decreased growth rate of all cell lines and decreased anchorage-independent colony formation in several malignant cell lines. All in vitro and in vivo effects were reversible following both short- and long-term (1 year) culture of cells in the presence of DMSO, suggesting epigenetic effects. These data support the concept of independent genetic controls for the invasiveness of tumours and the ability to form metastases.

Animals↗

PubMed1990

Cytogenetic profile of in vitro spontaneously transformed and chemical tumor-derived cell lines related to the mouse lung alveologenic carcinoma.

The karyotypes for a unique series of cloned untransformed and spontaneously and urethan-transformed mouse lung alveologenic carcinoma cell lines were compared by G-banding. All cell lines exhibited altered chromosome number accompanied by chromosomal aberrations. Both spontaneously and chemically transformed lines contained a higher proportion of cells carrying double minutes, short-arm chromosomes with no distinct banding pattern, and Robertsonian translocations between a variety of chromosomes. No common karyotypic abnormalities were observed among any of the transformed lines. These data suggest that enhanced genomic instability may lead to a critical subchromosomal molecular event(s) in generation of both spontaneously and chemically derived mouse lung alveologenic carcinoma.

Adenocarcinoma, Bronchiolo-Alveolar↗