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M Haas

Publications and source records attributed to M Haas.

At least 253 records · Page 14Linked to original sources
PubMed1987

Physiology and biophysics of chloride and cation cotransport across cell membranes.

Many important questions remain to be answered about the mechanism that mediates coupled Na,K,Cl cotransport. We still do not know what the ATP requirement involves. Is ATP the direct energy source? Such an energy source does not seem to be necessary, inasmuch as the net free energy in the combined transmembrane chemical gradients of Na, K, and Cl is quite sufficient to maintain the observed high Cl(i). Could a protein kinase-mediated mechanism be responsible for the ATP requirement? How does reducing Cl(i) stimulate the transporter? What are the kinetic relationships for the co-ions at the outward- and inward-facing transport sites? Are they symmetrical? Can the squid axon regulate its cell volume? If so, is the Na,K,Cl transporter directly involved? Thus, the squid axon remains a fruitful preparation to study a transport mechanism similar to that found in a variety of cells. Its large size confers unique experimental advantages that should help us in our quest to understand this widely distributed transport mechanism.

Animals↗
PubMed1987

Radiation leukemia virus and X-irradiation induce in C57BL/6 mice two distinct T-cell neoplasms: a growth factor-dependent lymphoma and a growth factor-independent lymphoma.

Two different classes of neoplastic T cells were isolated from radiation leukemia virus (RadLV)-inoculated and from X-ray-treated C57BL/6 mice. One consisted of growth factor-dependent T-cell lymphoma (FD-TCL) lines which were established from the spleens and thymuses of treated mice within a day of lymphoma detection. FD-TCL cells were often eudiploid and could be grown in pure culture only at high concentrations, or on stromal feeder layers. Non-thymic, factor-dependent TCL cells produced interleukin-2 upon lectin stimulation, and were autostimulatory because they secreted growth factor(s) constitutively. Single cell cloning of FD-TCL cells in semisolid medium required the addition of exogenous conditioned medium. In vivo, FD-TCL cells that were injected intraperitoneally or intravenously homed to the spleen, proliferated in it and killed the injected mice. FD-TCL cells did not produce local tumors at the site of subcutaneous injection. The isolation and study of FD-TCL cells was facilitated by their cultivation on stromal hematopoietic monolayers in supplemented "lymphocyte medium", until an autostimulating, self-sustaining concentration of FD-TCL cells was obtained. FD-TCL cells could not be grown from lymphoid tissue of normal, control mice. In contrast, T-cell lymphoma (TCL) lines, which were established from virus-induced thymomas which had been kept in situ for 4-6 weeks after detection, consisted of factor-independent cells that possessed an aneuploid karyotype (in some cases trisomic for chromosome No. 15), and produced local tumors at the site of subcutaneous injection. These cells could be cloned in semisolid medium without addition of exogenous factor(s). The phenotypic markers of TCL cells differed from those of FD-TCL cells, suggesting heterogeneity in the stages of differentiation at which cells can give rise to growth factor-independent (TCL) and to growth factor-dependent (FD-TCL) lines.

Animals↗
PubMed1987

Dynamic and kinetic differences of the vascular and myocardial effects of calcium antagonists in the rat heart.

We studied the effects of nifedipine, nimodipine, verapamil, D600 (gallopamil), D888 (desmethoxyverapamil), D890 (quaternized verapamil), bepridil, and diltiazem on the coronary flow and the left ventricular pressure in the retrogradely perfused paced rat heart; in addition, we investigated the time course of onset and recovery of these effects. We found a clear difference in potency order for the vascular and cardiac effects as well as widely different kinetics of coronary flow increase and negative inotropic activity. Furthermore, positive inotropism at low doses of some calcium antagonists seemed to be related to the vascular effects of these compounds. We conclude that the rat heart contains a hydrophylic and readily accessible, vascular "dihydropyridine" site and a more hydrophobic, possibly intramembraneous or intracellular, myocardial "verapamil" site with a lower accessibility for verapamil derivatives and bepridil.

Animals↗
PubMed1987

Photolabeling of a 150-kDa (Na + K + Cl) cotransport protein from dog kidney with a bumetanide analogue.

(Na + K + Cl) cotransport is the major mechanism of salt transport across the apical membrane of the epithelial cells of the thick ascending limb of Henle's loop of mammalian kidney and the site of action of "loop" diuretics such as furosemide and bumetanide. We have identified a 150-kDa protein in membranes from dog kidney cortex that is photolabeled by a radiolabeled, benzophenone analogue of bumetanide, [3H]4-benzoyl-5-sulfamoyl-3-(3-thenyloxy)benzoic acid ([3H]BSTBA). Several pieces of evidence strongly suggest that this 150-kDa protein is at least part of the (Na + K + Cl) cotransport system. 1) Photoincorporation of [3H]BSTBA into this protein is completely blocked by inclusion of 10 microM unlabeled bumetanide in the photolysis medium. 2) Photoincorporation of [3H]BSTBA into this protein shows a saturable dependence on [3H]BSTBA concentration, with a K 1/2 (approximately 0.1 microM) very similar to that for reversible [3H]BSTBA binding to kidney membranes. 3) Photolabeling of this protein by [3H]BSTBA requires the simultaneous presence of Na, K, and Cl in the photolysis medium. 4) When crude membranes from dog kidney cortex are centrifuged on sucrose density gradients, saturable [3H]bumetanide binding and photoincorporation of [3H]BSTBA in the 150-kDa region show a very similar distribution among the 15 gradient fractions collected. [3H]BSTBA is also photoincorporated into at least two lower molecular mass proteins, the largest of which is approximately 50 kDa.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

The induction of growth factor-independence in murine myelocytes by oncogenes results in monoclonal cell lines and is correlated with cell crisis and karyotypic instability.

Infection of established (IL-3)-dependent hematopoietic cell lines with Abelson murine leukemia virus (A-MLV) abrogates their requirement for IL-3 and leads to non-autocrine growth factor-independent cells. We were interested to determine whether A-MLV can induce IL-3 independence also in non-established cells. To obtain long-term cultures of diploid myelocytes, splenic hematopoietic cells were first infected with MMCV, a murine retrovirus carrying the avian v-myc oncogene. These cultures were superinfected with A-MLV. In three independent experiments, the first growth factor-independent cells appeared between 18 and 43 days after superinfection with A-MLV and represented .02-1% of the population. Furthermore, the cultures that became growth factor-independent were monoclonal for integration of the v-abl gene. These results indicate that the acquisition of growth factor-independence after superinfection of v-myc-expressing cells with A-MLV is a rare event. The low frequency of growth factor-independent cells was not due to a low percentage of infected cells, since 15-25% of the cells were infected with A-MLV after 7 days. The first appearance of growth factor-independent cells coincided with crisis in the cultures, as indicated by a high incidence of cell death and a reduced overall growth rate of the cell populations. These growth factor-independent cells exhibited variable karyotypes, including many that were near-triploid to near-tetraploid. In summary, growth factor-independence induced by super-infection with A-MLV, like that induced by double-infection with v-myc- and v-H-ras-containing viruses, is associated with unstable karyotypes. The growth factor-independent cells show variable ploidy characteristic of cells which survived crisis.

Animals↗
PubMed1987

Evidence against ras activation in human ovarian carcinomas.

Activation of ras genes in human ovarian carcinomas and ovarian carcinoma cell lines was tested by transfection of NIH 3T3 cells with high molecular weight DNA extracted from fresh tumors or from cell lines. Of 18 ovarian tumors and tumor cell lines that were exhaustively tested, only one yielded DNA active in focus-induction in this assay. Southern blot analysis of DNA in serially transformed NIH 3T3 foci revealed restriction fragments that hybridized with a probe specific for the human N-ras oncogene and with human repetitive (Alu) sequences. Individually transformed foci contained N-ras hybridizing fragments of different sizes. Northern blots of RNA extracted from different transformants revealed the expression of different transcripts hybridizing with the N-ras probe. The transformants also expressed a 700 base RNA that hybridized with a human B-lym probe. The low prevalence of ras activation in ovarian tumors as measured by transforming capability suggests that ras activation does not play an important role in the development of most human ovarian tumors.

Animals↗
PubMed1987

[Fibroscopy].

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Disinfection↗
PubMed1986

Specific sequences of the env gene determine the host range of two XC-negative viruses of the Rauscher virus complex.

Two viruses which do not give rise to XC plaques in the standard XC assay (XC-negative) have been isolated from the Rauscher virus (RV) complex. These viruses differ in their host range. One, R-MCF-1, is dualtropic and will therefore infect both murine and non-murine cells. However, unlike other mink cell focus-inducing (MCF) viruses, it cannot infect NIH 3T3 cells. The other, R-XC-, is ecotropic. It will infect murine cells, including NIH 3T3 cells, but does not infect mink lung cells. Analysis of hybrid viruses, in which homologous regions of the genomes of R-MCF-1 and R-XC- virus were exchanged, indicated that the NH2-terminal portion of the gp70 is responsible for the particular host ranges of these viruses. The nucleotide sequence of the env gene of R-XC- virus was therefore determined and compared with the known env sequences of ecotropic MLVs and dualtropic MCF viruses of the Rauscher and Friend virus complexes. R-XC- virus was found to be a recombinant virus. Its env gene contained sequences derived from an endogenous env gene which were closely related to those of the MCF viruses but differed from any previously described sequences. The particular properties of R-MCF-1 and R-XC- virus suggest that the two viruses arose by recombination between R-MLV and two endogenous env sequences which differ from those of the known MCF viruses. If so, this suggests that the mouse genome contains at least five env sequences which can give rise to MCF-like viruses. In addition, since the host range and interference properties of R-XC- virus are very similar to those of the previously described ecotropic recombinant viruses, it may be that the ecotropic recombinant viruses arose by recombination with the same endogenous env sequences as did R-XC- virus.

Animals↗
PubMed1986

[3H]bumetanide binding to duck red cells. Correlation with inhibition of (Na + K + 2Cl) co-transport.

Bumetanide is a potent inhibitor of cation-chloride co-transport systems in many cell types, including duck red cells. We studied equilibrium binding of [3H]bumetanide to intact duck red cells under a number of conditions known to affect (Na + K + 2Cl) co-transport in these cells. Saturable [3H]bumetanide binding to duck red cells is markedly stimulated by addition of norepinephrine or cell shrinkage, conditions which similarly stimulate co-transport. In the presence of norepinephrine and saturating concentrations of extracellular sodium, potassium, and chloride for the co-transporter, we found approximately 1000 [3H]bumetanide-binding sites/red cell, and measurement of 24Na+ influx on the same cells yielded a turnover number of approximately 4000/s for the co-transporter. 24Na+ influx was negatively correlated with the amount of bound [3H]bumetanide, and both saturable binding and inhibition of influx were half-maximal at approximately 10(-7) M [3H]bumetanide. Binding of [3H]bumetanide to duck red cells is stimulated in a saturable manner by increasing extracellular sodium and potassium. Chloride has a biphasic effect on [3H]bumetanide binding; increasing [Cl-]o (by replacement of methylsulfate) from 0 to 32 mM markedly enhances binding, whereas further increasing [Cl-]o to 160 mM inhibits binding. This behavior is similar to that reported for bumetanide inhibition of duck red cell (Na + K + 2Cl) co-transport (Haas, M., and McManus, T. J. (1983) Am. J. Physiol. 245, C235-C240; Haas, M., and McManus, T. J. (1982) Biophys. J. 37, 214a) and [3H]bumetanide binding to membranes from dog kidney outer medulla (Forbush, B. III, and Palfrey, H. C. (1983) J. Biol. Chem. 258, 11787-11792).

Acetates↗