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Biomedical subjects

J Law

Publications and source records attributed to J Law.

At least 127 records · Page 7Linked to original sources
PubMed1986

Production of a monoclonal antibody specific for seminomas and dysgerminomas.

A monoclonal antibody (M2A, IgG2a) was produced against a cultured human ovarian epithelial adenocarcinoma cell line, HEY. Monoclonal antibody M2A reacted with a glycoprotein of molecular weight 40,000 on the surface of HEY cells. The affinity constant of the monoclonal antibody M2A for HEY cells was 10(9) M-1, and the number of binding sites on HEY cells was 2 X 10(4) per cell. The monoclonal antibody produced positive immunoperoxidase staining of fetal (but not adult) testis and of seminomas and dysgerminomas but did not stain various normal adult tissues or other gonadal or extragonadal tumors. Monoclonal antibody M2A may be useful for confirming a histological diagnosis of seminoma and dysgerminoma.

Antibodies, Monoclonal↗
PubMed1986

Monoclonal antibodies to an epithelial ovarian adenocarcinoma: distinctive reactivity with xenografts of the original tumor and a cultured cell line.

Four monoclonal antibodies (mAb) (8C, 10B, M2A, and M2D) were produced against the human epithelial ovarian adenocarcinoma cell line, HEY. The affinity constants of binding of the mAb to cultured HEY cells were 8 X 10(8) M-1 (M2D) and 10(9) M-1 (8C and 10B). mAb 8C reacted with a major glycoprotein of Mr 90,000 on the surface of HEY cells. The four mAb differed from previously reported mAb to epithelial ovarian adenocarcinomas on the basis of their reactivity with cultured ovarian adenocarcinoma cell lines using a cell-binding radioimmunoassay, and their staining of cryostat sections of various human normal and tumor tissues using an immunoperoxidase reaction. All four mAb reacted with s.c. tumors derived by injecting cultured HEY cells into thymectomized CBA/CJ mice. However, only two of the four mAb (8C and 10B) also reacted with s.c. tumors of the original HEY xenograft from which the cultured cell line was derived. In addition, mAb 8C and 10B reacted by immunoperoxidase staining with 2 and 4 different cases, respectively, of 11 epithelial ovarian adenocarcinomas examined. Cultured HEY cells were adapted to grow i.p. in BALB/c-nu/nu mice and the i.p. tumors retained their reactivity with the monoclonal antibodies. These tumor-bearing mice offer a useful model system for studying the potential of mAb, especially 8C and 10B, for the diagnosis and treatment of patients with peritoneal extension of epithelial ovarian adenocarcinomas.

Adenocarcinoma↗
PubMed1985

Selective inhibition of cardiac cyclic nucleotide phosphodiesterases by doxorubicin and daunorubicin.

Doxorubicin and daunorubicin, the anthracycline antitumor agents, were evaluated for their in vitro and in vivo effect on phosphodiesterase (PDE) activity in mouse tissues. Doxorubicin at a concentration of 10(-4)M inhibited cardiac c-AMP (adenosine 3',5', monophosphate) PDE activity 50% of the control whereas in lungs and spleen, the activity was inhibited only 20%. On the contrary no effect was seen in kidney and liver. In addition, cardiac c-GMP (guanosine 3',5' monophosphate) PDE appeared less sensitive to doxorubicin than c-AMP PDE though inhibition in heart was more pronounced than in any other tissue. It appears that daunorubicin inhibits c-AMP PDE activity in heart markedly less than doxorubicin. Kinetic studies indicate that both inhibitions of c-AMP and c-GMP PDE by doxorubicin were non-competitive with substrate. Intravenous administration of 20 and 30 mg/kg of free doxorubicin to CDF1 mice resulted in 33 and 39% decreases in cardiac c-AMP PDE activity respectively by 72 hrs. In contrast, similar intravenous injections of same doses of doxorubicin entrapped in cardiolipin liposomes had no effect on c-AMP PDE activity in any tissues. These studies demonstrate the relative selectivity of the cardiac cyclic nucleotide PDE inhibitory effect of doxorubicin suggesting that this inhibition might be one aspect of the mechanism of anthracycline-induced cardiotoxicity.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1985

Problems associated with iridium-192 wire implants.

Three incidents are reported, from different radiotherapy centres, in which an implanted iridium-192 wire remained in the tissues of a patient after withdrawal of the plastic tubing in which it was contained. In each case the instrument used to cut the wire had probably formed a hook on the end of the wire which caused it to catch in the tissues. Detailed recommendations are made for avoiding such incidents in the future, the most important of which is that the patient should be effectively monitored after the supposed removal of all radioactive sources.

Aged↗
PubMed1985

Intramuscular triamcinolone acetonide in chronic severe asthma.

Seventeen subjects with chronic severe asthma completed a 48 week prospective, double blind study with crossover of treatment at 24 weeks, in which triamcinolone acetonide 80 mg intramuscularly every four weeks was compared with oral prednisolone 10 mg daily. Spirometry, twice daily measurements of peak expiratory flow rate, and self assessment of asthma symptom scores showed significant improvement during triamcinolone treatment; less extra prednisolone was required and there was significant weight loss. Two patients withdrew, one because of dissatisfaction with prednisolone and one because of side effects while taking triamcinolone. Three were withdrawn, one with proximal muscle weakness and two because of intercurrent illness. Adrenal suppression, bruising, and hirsuitism were worse with triamcinolone, other side effects being comparable. On completion of the study 16 of the 17 patients opted to continue taking triamcinolone acetonide. This treatment is an important addition to the therapeutic options available for chronic severe asthma.

Administration, Oral↗
PubMed1983

The synthesis of the brain specific S100 protein in colcemid resistant mutants of rat glial cells.

We have isolated two colcemid-resistant mutant sublines, CMR (7A) and CMR (7B), from rat glial cells, C6, using multiple consecutive selections with increasing concentrations of colcemid. The mutant sublines show a decreased uptake of [3H]colchicine but have no apparent defect in the cytoplasmic binding of the drug. The synthesis of the brain-specific S100 protein is less sensitive to colcemid inhibition in the mutant cell lines than in parental C6 cells, suggesting that colcemid must enter the cell to inhibit S100 protein synthesis.

Animals↗
PubMed1983

The structural conservation of S100 protein during evolution: analysis by reactivity with a monoclonal antibody.

A hybridoma cell line producing a monoclonal antibody (A4) against bovine S100 protein has been produced by fusing mouse myeloma P3X63/Ag8 cells with spleen cells from a BALB/c mouse immunized with bovine S100 protein. A4 is of the IgG2b subclass and was purified by affinity chromatography on a protein A-Sepharose column. Brain extracts from several mammalian and one avian species reacted both with polyclonal rabbit anti-S100 protein antiserum and with A4 in a radioimmunoassay. Brain extract from dog was a notable exception. It reacted with the rabbit antiserum but not with A4. Therefore A4 reacts with a common epitope that is present on S100 proteins from different vertebrate species but is absent on dog S100 protein.

Animals↗
PubMed1982

Binding of 2',5'-dideoxyadenosine to brain membranes. Comparison to P-site inhibition of adenylate cyclase.

Membranes from rat cerebral cortex and striatum contain a relatively large number of high-affinity binding sites for [3H]2',5'-dideoxyadenosine, [3H]adenine arabinoside, and [3H]adenosine. The binding of [3H]2',5'-dideoxyadenosine and [3H]adenine arabinoside was virtually unaffected by relatively specific agonists and antagonists for adenosine receptors, such as 2-chloroadenosine, N6-phenylisopropyladenosine or theophylline. Binding of [3H]adenosine was partially blocked by such receptor ligands. The specific binding of all three ligands was antagonized by a variety of adenosine analogs which inhibit adenylate cyclase by interaction with the so-called P-site associated with this enzyme. However, potencies of adenosine analogs as P-site inhibitors of adenylate cyclase and as antagonists of binding do not correlate well. 5'-Methylthioadenosine had high potency and efficacy versus binding of [3H]2',5'-dideoxyadenosine but had virtually no effect on activity of adenylate cyclase. 2-Fluoroadenosine was less potent than adenosine as an antagonist of specific binding of [3H]2',5'-dideoxyadenosine, while 2-fluoroderivatives of adenosine, adenine arabinoside and adenine xylofuranoside were more potent than the parent compounds as P-site inhibitors. The significance of the binding sites for [3H]2',5'-dideoxyadenosine remains unclear, but their presence complicates the use of [3H]adenosine and certain analogs as ligands for adenosine membrane sites associated with adenylate cyclase.

Adenosine↗
PubMed1981

Inhibition of fusion of embryonic muscle cells in culture by tunicamycin is prevented by leupeptin.

The carbohydrate requirement for alignment and fusion of embryonic quail muscle cells has been examined in tissue culture by use of tunicamycin (TM). The mononucleated, spindle-shaped proliferating myoblasts were treated with TM at various times before fusion and differentiation into multinucleated muscle fibers capable of spontaneous contraction. Tm blocked protein glycosylation and expression of glycoproteins on the cell surface, and strongly inhibited fusion when added to cultures of differentiating muscle cells before the fusion "burst," but had no apparent effect on cell alignment. The inhibition of fusion was partially prevented when TM was administered in the presence of protease inhibitors such as leupeptin and pepstatin, but the inhibition of glycosylation was not prevented. Both glycosylation and fusion were completely restored to normal by the removal of the antibiotic from the medium. These studies provide strong support for the idea that myoblast fusion is partially mediated by glycoproteins with asparagine-linked oligosaccharides. However, the requirement for the carbohydrate portion of the glycoprotein appears to be indirect in that it acts to stabilize the protein moiety against proteolytic degradation. Our findings do not rule out the possibility that oligosaccharide units of surface glycolipids have some role in myoblast fusion.

Animals↗
PubMed1980

Selective action of colchicine on protein synthesis and release in a clonal line of rat glial cells.

The effect of colchicine on protein synthesis and secretion in stationary cultures of clonal rat glial cells C6 was examined. Colchicine inhibited the synthesis of the brain specific S100 protein in intact cells but not in a cell-free protein synthesizing system derived from these cells. There was no demonstrable effect of the drug on the synthesis of any of the several hundred proteins resolved by a two-dimensional electrophoretic analysis. However, colchicine specifically enhanced the secretion of several proteins of molecular weighs of 30,000 and of 200-300,000 into the medium. Two of the high molecular weight proteins were apparently membrane proteins whose release into the medium was stimulated by the drug.

Animals↗
PubMed1979

Monitoring visual evoked response during craniofacial surgery.

A case is presented in which intraoperative visual evoked response (VER) monitoring was employed during correction of orbital hypertelorism. This procedure is noninvasive and does not interfere with the execution of the operation. The operative time is prolonged only a few minutes to record the VER. This technique is a simple and safe method for detecting intraoperative damage to the optic nerve and chiasm, and may prove useful in avoiding damage to these critical structures during craniofacial surgical procedures.

Child↗