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Biomedical subjects

L M Fink

Publications and source records attributed to L M Fink.

At least 73 records · Page 4Linked to original sources
PubMed1977

Studies on the iodinated surface membrane proteins and concanavalin A agglutination of transformed Syrian hamster cells.

Chemically transformed Syrian hamster cells exhibit marked agglutination in the presence of the plant lectin, concanavalin A. In this report, we describe conditions which can alter this concanavalin A agglutinability, and compare the surface proteins from transformed cells which express different degrees of agglutinability. Lactoperoxidase-catalyzed iodination of tertiary Syrian hamster cells reveals the major iodinatable protein to be approximately 220 000 daltons. The transformed Syrian hamster cells do not contain this protein in an iodinatable form. Analyses of the transformed cells grown under conditions which decrease the concanavalin A agglutinability do not demonstrate any iodination of the 220 000 mol. wt. protein. These results depict the effects of growth and dibutyryl cyclic AMP on the iodinatable cell surface proteins of transformed cells and indicate that the absence of the I-220 000 mol. wt. protein is probably not a major determinant of concanavalin A agglutination.

Animals↗
PubMed1977

Identification of transmembrane bridging proteins in the plasma membrane of cultured mouse L cells.

Studies were carried out to identify transmembrane bridging proteins in the plasma membrane of mouse L-929 cells. Cells grown in suspension culture were 125I-labeled by lactoperoxidase and allowed to ingest latex particles to produce inside-out membrane phagosome preparations. Phagosomes were isolated and the inner membrane surface was labeled with N-(5'-aminopentyl)-5-dimethylamino-1-naphthalenesulfonamide (dansylcadavarine) by a transglutaminase-catalyzed reaction. The phagosome membrane proteins were solubilized and dansylcadavarine-labeled proteins were isolated by anti-dansyl immunoadsorbent affinity chromatography. Dansylcadavarine-labeled proteins were analyzed by sodium dodecyl sulfate/polyacrylamide gel electrophoresis and autoradiography for the presence of 125I-labeled material. By this technique, two iodinated proteins with molecular weights of approximately 50,000 and 80,000 appear to be selectively retained by the anti-dansyl immunoadsorbent, suggesting that these proteins span the plasma membrane.

Cadaverine↗
PubMed1977

The effects of specific antibody-complement-mediated cytotoxicity on transformed and untransformed Syrian hamster cells.

Antibodies were produced against 220,000-molecular-weight proteins of Syrian hamster embryo cells. The antiserum containing these antibodies is capable of immunologically staining the surfaces and a fibrillar network around untransformed Syrian hamster embryo cells. The staining is removed by adsorption of the antiserum with Syrian hamster embryo cells and by mild trypsin treatment. Several lines of neoplastically transformed Syrian hamster embryo cells isolated and cloned after treatment with chemical carcinogens show little or no immune staining. Adsorption of the antiserum with certain transformed cells does not significantly reduce the immune staining of untransformed Syrian hamster embryo cells. The immune antiserum, in the presence of complement, is selectively cytotoxic to the untransformed Syrian hamster embryo cells. However, the transformed lines show resistance to this treatment. Analysis of the lactoperoxidase-catalyzed, iodinated cell surface proteins by sodium dodecyl sulfate-polyacrylamide gel electrophoresis reveals that the transformed lines have either no detectable labeling or a marked reduction in the labeling of 220,000-molecular-weight proteins that are major iodinatable cell surface proteins on untransformed Syrian hamster embryo cells.

Antibodies↗
PubMed1976

In vitro correlates of transformation in C3H/10T1/2 clone 8 mouse cells.

Various potential in vitro correlates of malignancy were studied in four chemically transformed C3H/10T1/2 Clone 8 mouse cell lines and were compared with controls cells. The degree of tumorigenicity was best predicted by the relative plating efficiencies of the morphologically transformed cells in soft agar. All transformed cells also showed an increase in extracellular fibrinolytic activity which may be an additional marker for transformation. Intracellular fibrinolytic activity and loss of 125I-labeled cell surface protein (M.W. 250,000) were not correlated with morphological transformation or tumorigenicity in these cells.

Agar↗
PubMed1976

Removal of basement membrane in the involuting breast.

Morphologic and immunohistochemical studies by light and electron microscopy indicated that basement membrane was removed during the process of involution of the murine breast. Removal of the basement membrane started 2 days postweaning, was maximal at 4 days, and correlated with degeneration of epithelial cells. There was no evidence of phagocytosis of basement membrane, so the removal of this antigen was attributed to enzymatic hydrolysis. To determine the activity of breast homogenate on the specific basement membrane antigen, insoluble basement membrane embedded in agarose gels was incubated with breast liver and kidney homogenates. When basement membrane antigen was demonstrated by the specific antibody, it was found that breast homogenate solubilized basement membrane but liver and kidney failed to solubilize basement membrane. To quantify the reaction and determine some of the characteristics of the responsible enzyme(s), insoluble basement membrane was labeled with 125I and the release of radioactivity into the supernatant following incubation with extracts of involuting breast indicated hydrolysis of basement membrane. Extracts of breast homogenate extensively hydrolyzed labeled basement membrane if naturally occurring inhibitors were removed by previous washing, whereas liver or kidney extracts prepared in a similar manner were devoid of activity. The hydrolysis of basement membrane was time and concentration dependent and had a pH optimum. The reaction was blocked by prior heating of the extract at 100 degrees C. for 30 minutes, removal of divalent cations, and presence of diisopropylfluorophosphate (a specific serine esterase inhibitor); prolonged dialysis failed to remove the hydrolytic activity. It is concluded that an enzyme system present in the involuting breast is capable of basement membrane hydrolysis

Animals↗
PubMed1975

The effect of modification of T7 DNA by the carcinogen N-1-acetylaminofluorene: termination of transcription in vitro.

To study the effects of N-2-acetylaminofluorene (AAF) modification of DNA on transcription, purified DNA from bacteriophage T7 was modified in vitro to varying extent with AAF and transcribed by DNA-dependent RNA polymerase from Escherichia coli. The main effects of AAF modification on transcription are a marked inhibition of the rate and extent of trna synthesis with relatively little effect on initiation except at very high AAF doses. Calibration of the percent modification with [14-C]AAF and analysis of the size of the RNA product by double isotope labeling and polyacrylamide gel electrophoresis support the following mechanism of transcription inhibition: most of the AAF residues bound to the coding strand of the DNA cause premature termination of transcription, at or near the site of modification, with release of RNA polymerase. This results in the production of shorter RNA chains with increasing amounts of bound carcinogen. The data are consistent with there being no reinitiation and/or synthesis of RNA distal to the AAF-modification site.

Carcinogens↗
PubMedDate not supplied

Effect of troglitazone on fibrinolysis and activated coagulation in patients with non-insulin-dependent diabetes mellitus.

The objective of this study was to determine if treatment of non-insulin-dependent diabetes mellitus (NIDDM) patients with the "insulin sensitizer" troglitazone, both as monotherapy and in combination with insulin, corrects the impaired fibrinolysis and activated coagulation associated with NIDDM. Patients participating in two clinical trials comparing troglitazone and placebo in patients with NIDDM were studied at the time of randomization and after 26 weeks of treatment. Eighteen patients were treated with troglitazone (ten in combination with insulin and eight as monotherapy) and eight were treated with placebo (four in each trial). Plasma concentrations of plasminogen activator inhibitor (PAI-1), prothrombin fragment F1+2, fibrinogen, and von Willebrand Factor (vWF) activity were measured. Plasma PAI-1 concentrations fell significantly from a mean of 68.8 +/- 32.3 ng/mL to 40.4 +/- 20.4 in the troglitazone treated group, but did not change significantly in the placebo treated group. Plasma PAI-1 concentrations were elevated in 15 patients treated with troglitazone and fell to normal in eight of them. There was no significant change in plasma F1+2, vWF, and fibrinogen, but plasma C-peptide and triglyceride concentrations fell significantly with troglitazone. This study demonstrates that troglitazone treatment is associated with a significant fall in plasma PAI-1 antigen concentrations in patients with NIDDM and, therefore, may have a beneficial effect on fibrinolysis.

Adult↗
PubMedDate not supplied

Plasma homocysteine concentrations in type II diabetic patients in India: relationship to body weight.

Hyperhomocysteinemia has been established as a risk factor for cardiovascular disease and occurs with a high prevalence in patients with type II diabetes and microvascular disease. In order to determine whether plasma homocysteine concentrations vary with body-mass index in patients with type II diabetes, we measured plasma homocysteine in lean, normal weight, and overweight subjects living in India. Plasma homocysteine concentrations were significantly lower in the lean persons with diabetes when compared to those who were obese and compared to control subjects (p < 0.02). We conclude that plasma homocysteine concentrations are lower in lean persons with type II diabetes and that this efficiency in homocysteine metabolism may contribute towards protection from cardiovascular disease in this population.

Adult↗
PubMedDate not supplied

Effects of perfluorochemical on phagocytic function of leukocytes.

Oxygen-carrying perfluorochemical emulsions may become useful for transfusions when red cells cannot be used. Since accumulation of perfluorochemicals in reticuloendothelial cells has been demonstrated, we tested the phagocytic function of monocytes and neutrophils in rabbit and human blood exposed in vivo and in vitro, respectively, to perfluorotributylamine (Oxypherol) a perfluorochemical blood substitute. Neutrophil and monocyte phagocytosis was assessed by determining the uptake of serum-coated fluorescent beads by monocytes and neutrophils in whole blood. Morphologic changes were assessed by electron microscopy. The phagocytic activity of monocytes and neutrophils in the blood of four rabbits injected 4 hours earlier with 70 to 85 ml of Oxypherol (28 ml/kg) was depressed by 87 +/- 1.0 percent. Neutrophils in this blood showed morphological alterations characterized by swelling and extensive vacuole formation. Similar changes were found in neutrophils and monocytes of human blood incubated with Oxypherol (10-50%, V/V) at 37 degrees C for 1 hour. The phagocytic activity of human neutrophils and monocytes exposed to 20 percent, V/V Oxypherol was depressed by 35 +/- 9.9 percent. We conclude that caution should be exercised when administering perfluorochemical blood substitutes in patients exposed or at risk of infection.

Animals↗
PubMedDate not supplied

Effect of perfluorochemical blood substitutes on human neutrophil function.

This investigation was undertaken to determine the influence of perfluorochemical blood substitutes (PFCs) on human neutrophil function. Neutrophils isolated from blood of healthy donors were incubated at 37 degrees C for 1 hour with 25 percent Oxypherol (perfluorotributylamine) or Fluosol-DA (perfluorodecalin and perfluorotripropylamine) in the presence of fresh autologous serum. In comparison to cells incubated with Hank's balanced salt solution (buffer), neutrophils exposed to PFCs were markedly inhibited in their chemotactic and phagocytic responses. With 25 percent PFCs, chemotaxis to zymosan-activated serum was inhibited to approximately 25 percent of control by Fluosol-DA and 11 percent by Oxypherol. Phagocytosis of polystyrene beads in the presence of fresh serum was decreased to 52 and 50 percent of control by both Oxypherol and Fluosol-DA, respectively. Neutrophils exposed to PFCs aggregated slower and with an extended activation time upon addition of phorbol myristate acetate (PMA). When activated with n-formyl-methionyl-leucyl-phenylalanine (FMLP), neutrophils exposed to PFCs aggregated at a faster rate but with a longer lag phase in comparison to control cells. Neutrophil superoxide (O-2) release stimulated by PMA also was depressed by prior exposure of cells to Oxypherol (6 nmoles O-2/1.5 X 10(6) neutrophils) compared to buffer (32 nmoles O-2/1.5 X 10(6) neutrophils). PMA-stimulated neutrophil adherence was depressed significantly by prior exposure to Fluosol-DA compared to control. In contrast, Oxypherol had insignificant influence on stimulated adherence. Since PFCs have a profound influence on several important neutrophil functions, patients receiving PFC should be monitored closely for possible infectious complications.

Blood Substitutes↗