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Biomedical subjects

M Shearer

Publications and source records attributed to M Shearer.

At least 37 records · Page 2Linked to original sources
PubMed1991

Efficient immortalization of luminal epithelial cells from human mammary gland by introduction of simian virus 40 large tumor antigen with a recombinant retrovirus.

When defined in terms of markers for normal cell lineages, most invasive breast cancer cells correspond to the phenotype of the common luminal epithelial cell found in the terminal ductal lobular units. Luminal epithelial cells cultured from milk, which have limited proliferative potential, have now been immortalized by introducing the gene encoding simian virus 40 large tumor (T) antigen. Infection with a recombinant retrovirus proved to be 50-100 times more efficient than calcium phosphate transfection, and of the 17 cell lines isolated, only 5 passed through a crisis period as characterized by cessation of growth. When characterized by immunohistochemical staining with monoclonal antibodies, 14 lines showed features of luminal epithelial cells and of these, 7 resembled the common luminal epithelial cell type in the profile of keratins expressed. These cells express keratins 7, 8, 18, and 19 homogeneously and do not express keratin 14 or vimentin; a polymorphic epithelial mucin produced in vivo by luminal cells is expressed heterogeneously and the pattern of fibronectin staining is punctate. Although the cell lines have a reduced requirement for added growth factors, they do not grow in agar or produce tumors in the nude mouse. When the v-Ha-ras oncogene was introduced into two of the cell lines by using a recombinant retrovirus, most of the selected clones senesced, but one entered crisis and emerged after 3 months as a tumorigenic cell line.

Animals↗
PubMed1991

Relationship between outlet obstruction constipation and obstructed urinary flow.

Ten women with symptoms and radiological features of outlet obstruction constipation underwent urodynamic bladder studies. The results were compared with ten age- and sex-matched controls. The mean (s.e.m.) peak flow rate for patients was 19.4 (6.4) ml/s compared with 32.1 (7.2) ml/s for controls (P less than 0.05). The mean (s.e.m.) voiding time for patients was 62.9 (23.7) s against a corresponding value of 15.6 (6) for controls (P less than 0.05). The mean (s.e.m.) bladder volume in patients was 482 (80) ml compared with a control value of 254 (112) ml (P less than 0.03). The mean (s.e.m.) detrusor pressure during the voiding phase was 53.3 (12) cmH2O. These results demonstrate that patients with outlet obstruction constipation have a generalized pelvic floor disorder resulting in obstructed urinary flow.

Constipation↗
PubMed1989

Use of a selectable marker regulated by alpha interferon to obtain mutations in the signaling pathway.

We have selected mutations in genes encoding components of the signaling pathway for alpha interferon (IFN-alpha) by using a specially constructed cell line. The upstream region of the IFN-regulated human gene 6-16 was fused to the Escherichia coli guanine phosphoribosyltransferase (gpt) gene and transfected into hypoxanthine-guanine phosphoribosyltransferase-negative human cells. These cells express gpt only in the presence of IFN-alpha. They grow in medium containing hypoxanthine, aminopterin, and thymidine plus IFN and are killed by 6-thioguanine plus IFN. Two different types of mutants were obtained after treating the cells with mutagens. A recessive mutant, selected in 6-thioguanine plus IFN, was completely resistant to IFN-alpha but responded normally to IFN-gamma and, unexpectedly, partially to IFN-beta. A constitutive mutant, selected in hypoxanthine-aminopterin-thymidine alone, was abnormal in expressing endogenous genes in the absence of IFN. Both types revert infrequently, allowing selection for complementation of the defects by transfection.

Blotting, Northern↗
PubMed1988

The development of hypoprothrombinaemia following antibiotic therapy in malnourished patients with low serum vitamin K1 levels.

A group of nine well-nourished patients, with normal serum vitamin K1 levels (mean 546, range 310-1350 pg/ml), maintained normal prothrombin times (PTs) and factor VII clotting activities throughout a 7 d course of i.v. cefotetan disodium, an N-methyl-thiotetrazole (NMTT) containing cephalosporin antibiotic. However, 11 of 20 patients, with acute intra-abdominal sepsis and initially normal PTs who underwent emergency surgery, developed prolonged PTs (INR 1.4-3.1) associated with reduction in factor VII activities (0.74-0.38 u/ml) after 3-7 d of antibiotic therapy. Nine of these 11 patients had clinical evidence of malnutrition and nine had subnormal serum vitamin K1 levels (mean 119, range 43-354 pg/ml) on admission. Seven received cefotetan but four were treated with a non-NMTT-containing cephalosporin or antibiotics belonging to other groups. The nine patients who maintained normal PTs all had normal nutritional status and normal serum vitamin K1 levels (mean 279, range 103-915 pg/ml) at presentation. The PT is a relatively insensitive indicator of vitamin K stores, and malnourished patients with low serum vitamin K1 levels are at risk of developing hypoprothrombinaemia following intravenous antibiotic therapy.

Adult↗
PubMed1987

Epitopes of human interferon-alpha defined by the reaction of monoclonal antibodies with alpha interferons and interferon analogues.

Five monoclonal antibodies reactive with human interferon (HuIFN)-alpha 2, but not with HuIFN-alpha 1, have been analyzed for their reaction with a series of IFN analogues and hybrid IFN molecules. Using analogues containing alpha 1 or gamma substitutions, it was shown that amino acids in the 107 to 113 region are implicated in the epitopes recognized by four of the five antibodies tested. Surprisingly, two of the antibodies that did not react with [alpha 1(113 to 114)112 to 113]alpha 2 also did not react with a truncated IFN-alpha 2(4 to 155). The presence of an epitope determined by amino acids at 112 and 113 and by the amino and carboxyl ends of the molecule supports a model for IFN where the carboxyl- and amino-terminals are adjacent to the proposed reverse turn around amino acid 110 to 115. The fifth alpha 2 specific antibody whose reaction with HuIFN-alpha 2 is not affected by the above substitutions and truncations recognizes IFN or IFN hybrids that, like alpha 2, have arginine at position 120, but does not react with IFN that, like alpha 1, have lysine at position 120. Amino acids 107 to 113 and 120 lie in regions of the molecule that have high hydrophilicity and are probably structurally involved in the epitopes recognized by the antibodies. Under conditions of antibody excess, the antibodies described here inhibit binding of HuIFN-alpha 2 to both human and bovine cells.

Animals↗
PubMed1987

Regulation of cell growth by interferon.

Interferons can regulate growth and differentiation in a wide range of cell types. These mechanisms are currently being examined. Interferons inhibit the growth of tumour cells and are thus potential anti-cancer agents. They can also inhibit normal cell growth in vitro, and stimulate tumour cell growth in vitro. They may also be involved in some autoimmune diseases. This review examines the effect of interferons on cell proliferation, function, and growth, focusing primarily on in vitro cell systems.

Animals↗
PubMed1987

The effects of cefotetan disodium on haemostasis.

A 7-day course of intravenous cefotetan disodium was given to nine patients. No significant changes were observed in haematological or biochemical parameters and serum vitamin K1 levels, prothrombin times, factor VII levels, thrombin times and activated partial thromboplastin times remained within the normal ranges throughout the treatment period in all patients. There was no evidence of clinical bleeding in any patient although in two the bleeding time was prolonged up to 13.0 min after 7 days' therapy. Notably, adenosine-5-diphosphate (ADP)-induced platelet aggregation responses were significantly increased (P less than 0.05) at the end of the treatment period. These data indicate that cefotetan disodium at a dose of up to 4 g daily can be used without risk of a bleeding diathesis. In situations associated with vitamin K1 deficiency, potential prolongation of the prothrombin time should be avoided by prophylactic vitamin K1 administration.

Adult↗
PubMed1987

Vitamin K1 content of maternal milk: influence of the stage of lactation, lipid composition, and vitamin K1 supplements given to the mother.

Using a sensitive electrochemical assay for vitamin K1 and standardized techniques for breast-milk collection, we studied the vitamin K1 content of human milk during the first 5 wk of lactation with respect to 1) individual and interindividual differences, 2) the relationship of vitamin K1 to other lipids, and 3) the influence of oral supplements of vitamin K1 on breast milk concentrations. Comparison of fore and hind milk from the mothers revealed higher vitamin K1 concentrations in hindmilks, suggesting that the lipid content influences the vitamin K1 concentration in maternal milk. Samples of maternal milk from nine mothers collected from day 1 to day 36 of lactation showed significantly higher vitamin K1 concentrations in colostral milk than in mature milk. For colostral milk there was a significant correlation of vitamin K1 to cholesterol (r = 0.62) but not to total lipid or phospholipid suggesting a role for cholesterol in the secretion of vitamin K1 into colostral milk. For mature milk correlation coefficients of vitamin K1 with all lipids were low (r = 0.29-0.37) suggesting that at later stages of lactation dietary fluctuations of vitamin K1 may be a more important determinant of the vitamin K1 content of breast milk than the lipid composition. To test the influence of diet, mothers were given oral supplements of vitamin K1.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1986

Effects of N-methyl-thiotetrazole cephalosporin on haemostasis in patients with reduced serum vitamin K1 concentrations.

Two patients with low random serum vitamin K1 concentrations but with normal prothrombin times and normal biological assays of the vitamin K dependent coagulation proteins were treated with an N-methyl-thiotetrazole cephalosporin (cefotetan) postoperatively. Four to six days later both patients developed a prolonged prothrombin time and a noticeable and specific lowering of the clotting activities of factors II, VII, IX and X, though the serum vitamin K1 concentrations remained unchanged. Crossed immunoelectrophoresis of prothrombin showed the appearance of a second peak corresponding to descarboxyprothrombin (PIVKA II). These abnormalities corrected after vitamin K administration. These data are consistent with the hypothesis that cephalosporins with an N-methyl-thiotetrazole side chain inhibit the hepatic utilisation of vitamin K but that this only causes hypoprothrombinaemia when liver reserves of vitamin K are low.

Aged↗
PubMed1986

Localization of interferons and interleukin 2 in polymyositis and muscular dystrophy.

Muscle biopsies from nine patients with polymyositis, six with muscular dystrophy, six with other muscle diseases and three controls have been studied with a panel of 10 monoclonal antibodies (MoAb) identifying T lymphocytes, HLA-class I antigens, alpha, beta and gamma interferons and interleukin 2 (IL-2). The result confirm that the staining of the sarcolemma with anti-HLA class I antibody is weak or negative, except in areas adjacent to infiltrating leucocytes or where muscle fibre damage is evident. The very similar tissue distribution of alpha, beta and gamma interferons in the polymyositis biopsies supports the hypothesis that interferons are released by the inflammatory infiltrate and induce the class I antigen expression. In contrast, little interferon was demonstrated in the dystrophic muscle implying that class I expression in these disorders must occur by a different mechanism. Little IL-2 was demonstrated in any of the biopsies though some unexplained small dense accumulations were identified by one of the anti IL-2 MoAb.

Adult↗