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Biomedical subjects

M Whitman

Publications and source records attributed to M Whitman.

At least 73 records · Page 4Linked to original sources
PubMed1986

Retrovirus shuttle vector for study of kinase activities of pp60c-src synthesized in vitro and overproduced in vivo.

We have constructed a recombinant murine retrovirus which efficiently transduces avian pp60c-src into murine cells and which is easily rescued from infected cells in plasmid form. To characterize the virus, several randomly selected NIH 3T3 lines were isolated after infection with recombinant retroviral stocks. All lines overproduced avian pp60c-src and appeared morphologically normal. Immunoprecipitates made from these lines with antisera specific for pp60c-src were tested for their kinase activities in vitro. We find that both autokinase and enolase kinase activities increase proportionately with the level of pp60c-src in the immunoprecipitates. To further test the authenticity of the pp60c-src encoded by the retroviral vector, these analyses were repeated in the presence of polyomavirus middle T antigen. Avian pp60c-src was activated as a protein kinase, indicating that the virally encoded pp60c-src interacts normally with middle T antigen. Interestingly, by increasing the intracellular levels of pp60c-src 15-fold over normal endogenous levels, we were unable to obtain a proportionate increase in the amount of middle-T-antigen-pp60c-src complex. Finally, using the shuttle features designed into the vector, we have isolated the first fully processed cDNA encoding functional avian pp60c-src X pp60c-src synthesized in vitro with this cDNA had intrinsic protein kinase activity and no detectable phosphatidylinositol kinase activity.

Animals↗
PubMed1986

Phosphatidylinositol kinases and cell transformation.

Products of phosphatidylinositol (PI) turnover have recently been implicated as regulators of cell growth and differentiation. Transformation of cells in culture by infection with certain viruses (Rous sarcoma virus, Kirsten sarcoma virus, and polyoma virus) or by transfection with the oncogenes carried by these viruses affect the steady-state level of intermediates in the PI turnover pathway. In addition, immunoprecipitates of the transforming gene products of Rous sarcoma virus and polyoma virus contain activities of certain enzymes in the PI turnover pathway. We have previously reported that polyoma middle T immunoprecipitates can catalyze phosphorylation of PI to phosphatidylinositol-4-phosphate (PIP). This activity is not intrinsic to middle T or pp60c-src but is due to a cellular enzyme that specifically associates with the middle T/pp60c-src complex. The PI kinase is found in immunoprecipitates of the middle t protein from polyoma viruses that are capable of cell transformation but does not associate with mutants of middle t defective in transformation, suggesting that this association may be important for transformation. Two PI kinases from fibroblasts (type I and type II) that are separable by anion exchange chromatography have been partially purified and characterized. These enzymes differ in their Km for ATP as well as their Ki for adenosine and ADP. Only the type I PI kinase specifically associates with the transformation-competent mutants of middle T.

1-Phosphatidylinositol 4-Kinase↗
PubMed1986

Vascular vasopressin receptors mediate inhibition of beta adrenergic receptor-induced cyclic AMP accumulation.

Beta adrenergic receptor agonists and forskolin stimulated cyclic AMP (cAMP) accumulation in cultured rat aortic smooth muscle cells (A-10). Furthermore, these cells display a high density of vasopressin receptors of the vascular (V1) subtype. Addition of vasopressin to these cells inhibited beta adrenergic agonist- and forskolin-stimulated cAMP accumulation by 30 to 40% and by 25 to 35%, respectively. The extent of inhibition was dependent on the concentration of vasopressin used. Half-maximal inhibition of cAMP accumulation by isoproterenol occurred at 8 X 10(-10) M vasopressin. Basal cAMP levels were not affected. The inhibition by arginine vasopressin was mediated by V1 receptors because the V2 renal receptor subtype selective agonists (1-deamino, 8-D-arginine)vasopressin and (1-deamino,4-valine,8-D-arginine)vasopressin were ineffective. Of the antagonists tested, the V1-selective antagonist [1-(beta-mercapto-beta,beta-cyclopentamethylenepropionic acid),2-(O-methyl)tyrosine,8-arginine]vasopressin was more potent than the mixed V1/V2 antagonist [1-beta-mercapto--beta, beta-cyclopentamethylenepropionic acid), 2-D-(O-ethyl)tyrosine,4-valine 8-arginine]vasopressin. The V2-selective antagonist [1-(beta-mercapto-beta,beta-cyclopentamethylenepropionic acid),2-D-isoleucine,4-valine,8-arginine]vasopressin displayed minimal ability to block the vasopressin-mediated inhibitory effect. These data demonstrate that in rat aortic smooth muscle cells V1 receptors are negatively coupled to adenylate cyclase. The studies presented suggest that the vasoconstrictor activity of vasopressin might involve inhibition of beta adrenergic receptor-mediated vascular relaxation through inhibition of cAMP accumulation.

Animals↗
PubMed1986

Phosphoinositide kinase activity and transformation.

We have used the DNA tumor virus polyoma as a model system to examine whether the phosphatidylinositol (PI) turnover pathway is a critical target for transforming gene products. Polyoma-infected cells show elevated levels of polyphosphoinositides and polyphosphoinositols, and a PI kinase activity is associated with middle T antigen, a transforming gene product of polyoma virus. In anti-T immunoprecipitates from polyoma-infected or -transformed cells, comparisons of wild-type and polyoma mutants defective for transformation show a strong correlation between middle T-associated PI kinase activity and transforming ability. Middle T has previously been found to associate at the plasma membrane with pp60 c-src and to activate it as a tyrosine kinase. c-src itself does not appear to phosphorylate PI; however, the middle T/pp60 c-src tyrosine kinase activity may be important for activation of PI kinase. Ammonium orthovanadate, a tyrosine phosphatase inhibitor, elevates the middle T/pp60 c-src-associated PI kinase activity. We propose that middle T/pp60 c-src activates a PI kinase and modulates PI turnover in vivo by tyrosine phosphorylation.

1-Phosphatidylinositol 4-Kinase↗
PubMed1986

Modulation of the antitumor and biochemical properties of bis(diphenylphosphine)ethane with metals.

Bis(diphenylphosphine)ethane (DPPE) and its bis[chlorogold(I)] [DPPE(Au2Cl2)], and bis[trichlorogold(III)] [DPPE(Au2Cl6)], complexes have in vivo antitumor activity. To determine if interaction with metals in situ can play a role in the antitumor activity of DPPE, we have studied the effects of DPPE, DPPE(Au2Cl2), DPPE(Au2Cl6) and mixtures of DPPE with metal salts on in vitro and in vivo biological systems. The in vitro cytotoxic potencies of the two DPPE-gold complexes were approximately 10-fold greater than that of DPPE. In addition, the cytotoxic potency of DPPE was increased when incubated with cells in the presence of Au(III) and Cu(II) salts, whereas Mg(II), Zn(II), Mn(II), Fe(II), Co(II), and Cd(II) had no effect. The effects of DPPE, DPPE(Au2Cl2) and mixtures of DPPE and metal salts on the activity of a model enzyme system, DNA polymerase alpha were measured. While DPPE did not inhibit the activity of DNA polymerase alpha, the DPPE(Au2Cl2) complex and mixtures of DPPE and Cu(II) salts inhibited the activity of the enzyme. Consistent with the effects observed in vitro, coadministration of Cu(II) or Au(III) increased the in vivo potency of DPPE in mice bearing i.p. P388 leukemia. Fifteen other DPPE analogues were evaluated for in vivo antitumor activity and for the effect of Cu(II) on their in vitro cytotoxic potency; there was a relationship between the ability of Cu(II) to potentiate the cytotoxic activities of DPPE analogues and their having in vivo antitumor activity.

Animals↗
PubMed1984

Evidence that the Rous sarcoma virus transforming gene product phosphorylates phosphatidylinositol and diacylglycerol.

The ability of purified Rous sarcoma virus transforming gene product, pp60v-src, to phosphorylate phosphatidylinositol and diacylglycerol was investigated. Phosphatidylinositol was phosphorylated to form both mono- and diphosphorylated derivatives. 1,2-Diacylglycerol was phosphorylated to form phosphatidic acid. These activities showed the same thermolability and the same sensitivity to inhibitors as shown by the casein kinase activity of pp60v-src. In addition, when serum-starved chicken embryo fibroblasts transformed by a virus mutant temperature-sensitive for transformation were shifted from the nonpermissive to permissive temperature, an increase of 50-100% in the labeling of phosphatidylinositol 4-phosphate, phosphatidylinositol 4,5-bisphosphate, and phosphatidic acid was observed, as compared to uninfected cells.

Animals↗
PubMed1981

Maternal and personality determinants of adolescent smoking behavior.

This study examined the interconnection of maternal determinants and personality attributes of adolescent male tobacco users. The 39 mothers and their 39 sons were interviewed separately about their attitudes and the mother's child-rearing practices. The sons also responded to questions concerning their personality characteristics. In general, the findings indicated that adolescent tobacco use depends on the coexistence of certain personality predispositions and maternal conditions. Thus, with regard to personality factors, male smokers tended to be less in control of their impulses, less responsible and autonomous, more rebellious, and more likely to engage in interpersonal aggression. With respect to the coexisting maternal conditions, the mothers of smokers tended to be less traditional and affectionate, and less likely to serve as models for their sons.

Adolescent↗
PubMedDate not supplied

Association of phosphatidylinositol kinase activity with polyoma middle-T competent for transformation.

Polyoma middle-T antigen is required for viral transformation of cultured cells and for tumorigenesis in animals. Like many other transforming gene products, middle-T is bound to the membrane and has an associated tyrosine kinase activity in vitro. This activity seems to result from the interaction of middle-T with pp60c-src, the cellular homologue of the transforming gene product of the Rous sarcoma virus, pp60v-src (refs 3-5). Both pp60v-src (ref. 6) and another retrovirus transforming gene product, pp68v-ros (ref. 7) were shown recently to have an associated phosphatidylinositol (PI) kinase activity in vitro and to increase PI turnover in vivo. These results suggest that viral transformation may be directly connected to a complex network of second messengers generated from PI turnover. Here, we assayed for PI kinase activity in immunoprecipitates made with middle-T- or pp60c-src-specific antisera of cells infected with polyoma virus. A PI kinase activity was detected in those immunoprecipitates which contained middle-T. Studies of mutants of middle-T defective in transformation indicate a close correlation between PI kinase activity and transformation.

1-Phosphatidylinositol 4-Kinase↗
PubMedDate not supplied

Understanding the perceived need for complementary and alternative nutraceuticals: lifestyle issues.

Nutraceuticals are biological therapies used to promote wellness, prevent malignant processes, and control symptoms. The use of complementary and alternative nutraceuticals increased dramatically after passage of the Dietary Supplement and Health Education Act of 1994. Motivations for use of these products include changes in eating patterns, concerns about adequacy of consumer food supply, and interactions with conventional healthcare providers that are perceived to be insensitive, too brief, or uncaring. By becoming knowledgeable about complementary and alternative nutraceuticals and the nutritional needs of people with cancer, communicating with empathy and patience, and involving dietitians, pharmacist, and other professional providers as needed, oncology nurses can provide accurate information and support for people with cancer and their families.

Complementary Therapies↗