Search PubMed⌕ Search

Biomedical subjects

M Haas

Publications and source records attributed to M Haas.

At least 235 records · Page 13Linked to original sources
PubMed1989

Stimulation of K-C1 cotransport in rat red cells by a hemolytic anemia-producing metabolite of dapsone.

Dapsone, a sulfone compound used in the treatment of leprosy and, more recently, Pneumocystis carinii pneumonia, produces as a major side effect a hemolytic anemia. This anemia is characterized by oxidation of hemoglobin to methemoglobin and increased splenic uptake of red blood cells. Using a rat model, Grossman and Jollow (J. Pharmacol. Exp. Ther. 244: 118-125, 1988) found that dapsone hydroxylamine (DDS-NOH), a dapsone metabolite, is responsible for its hemolytic effect in vivo. DDS-NOH also promotes hemoglobin binding to SH groups on rat red cell membrane proteins (Budinsky et al., FASEB J. 2: A801, 1988). Since the binding of hemoglobin and other reagents (e.g., N-ethylmaleimide) to membrane SH groups has been associated with increased K transport in red blood cells, we examined the effect of DDS-NOH on K efflux from rat red blood cells in vitro. Cells shrink when exposed to DDS-NOH (100 microM) in media with plasma-like ionic composition. This shrinkage is prevented if extracellular K is raised to 110 mM or if intra- and extracellular Cl are replaced by methylsulfate (MeSO4), suggesting involvement of a K-Cl cotransport pathway. Indeed, 100 microM DDS-NOH produces a 4- to 5-fold increase in K efflux in cells containing Cl but less than a 2-fold increase in cells containing MeSO4. This stimulatory effect is specific for K; Na efflux is slightly inhibited by 100 microM DDS-NOH. The concentrations of DDS-NOH required for half-maximal stimulation of Cl-dependent K efflux (53 microM) is similar to its half-maximal hemolytic concentration in rats (approximately 100 microM). Furthermore, the stimulation of Cl-dependent K efflux by DDS-NOH is greater than 80% reversed by subsequent treatment of the cells with dithiothreitol, suggesting involvement of SH groups. Our results indicate that DDS-NOH exposure stimulates an apparent K-Cl cotransport in rat red blood cells, resulting in cell shrinkage under physiological ionic conditions. Since shrinkage of red blood cells renders them less deformable (Mohandas et al., J. Clin. Invest. 66: 563-573, 1980), this suggests a pathophysiological mechanism whereby DDS-NOH exposure in vivo could promote increased splenic uptake of red blood cells and hemolytic anemia.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗
PubMed1989

[Periodontal aspects of care of partially edentulous jaws].

After an initial periodontal therapy to reduce bleeding a pocket depth and after reaching an AOI below 30% it is possible to make an apical reposition-flap. It is apt to supragingivalize the margins of restorations of fractured teeth or in case of subgingival lesions or preparation margins. In combination with a good recall-system thus the prognosis of periodontal treatment can be optimized.

Denture, Partial, Removable↗
PubMed1989

[Bonded porcelain laminates--an alternative to anterior porcelain crowns].

The trend towards esthetic dentistry, which originates in the USA, has added new dimensions to the treatment of anterior teeth. One of it is the porcelain laminate technique. Using composites, extremely thin, manually prepared porcelain laminates with a thickness of 0.3 to 0.5 mm are bounded to the labial aspect of front teeth or laterals. On account of the low laminate thickness very little enamel preparation is needed. The residual enamel mass and the translucency of the ceramic material produce a natural appearance and optimal cosmetic results. This technique enables the dentist to restore the shape and color of esthetically compromised teeth.

Composite Resins↗
PubMed1989

[Periodontal aspects of removable partial dentures].

Periodontal pre-treatment of patients receiving partial dentures should involve three phases: initial therapy; periodontal surgery; home care. For periodontal surgery and/or prosthodontic treatment using precision materials, e.g. telescope retainers, the API (approximal plaque index) should not exceed 30%. To prevent further loss of gingival attachment due to iatrogenic irritation by the dentures preparation of abutments should consistently the para- or supragingival. In patients with few residual teeth telescope retainers, which can be cemented for definitive fit if indicated, are the treatment of choice.

Dental Abutments↗
PubMed1988

Photoaffinity labelling of a 150 kDa (Na + K + Cl)-cotransport protein from duck red cells with an analog of bumetanide.

We have used a radiolabelled, benzophenone analog of bumetanide, 4-[3H]benzoyl-5-sulfamoyl-3-(3-thenyloxy)benzoic acid ([3H]BSTBA) to photolabel plasma membranes from duck red blood cells. BSTBA, like bumetanide, is a loop diuretic and a potent inhibitor of (Na + K + Cl) cotransport, and [3H]BSTBA binds to intact duck red cells with a high affinity similar to that of [3H]bumetanide (K 1/2 congruent to 0.1 microM). We incubated duck red cells with [3H]BSTBA, then lysed the cells and exposed the ghosts to ultraviolet light. The ghosting and photolysis was done at 0 degree C to prevent dissociation of the [3H]BSTBA. The ghosts were then sonicated to remove the nuclei and run on SDS-polyacrylamide gels. Analysis of H2O2-digested gel slices revealed [3H]BSTBA to be incorporated into a protein of approx. 150 kDa. This is the same molecular weight we obtain for a protein from dog kidney membranes which is photolabelled by [3H]BSTBA in a manner highly consistent with labelling of the (Na + K + Cl) cotransporter (Haas and Forbush (1987) Am. J. Physiol. 253, C243-C252). Several lines of evidence strongly suggest that the 150 kDa protein from duck red cell membranes is an integral component of the (Na + K + Cl)-cotransport system in these cells: (1) Photolabelling of this protein by [3H]BSTBA is blocked when 10 microM unlabelled bumetanide is included in the initial incubation medium with [3H]BSTBA; (2) Photoincorporation of [3H]BSTBA into the 150 kDa protein is markedly increased when the initial incubation medium is hypertonic or contains norepinephrine, conditions which similarly stimulate both (Na + K + Cl) cotransport and saturable [3H]bumetanide binding in duck red cells; (3) The photolabelling of this protein shows a saturable dependence on [3H]BSTBA concentration, with a K1/2 (0.06 microM) similar to that for the reversible, saturable binding of [3H]BSTBA and [3H]bumetanide to duck red cells; and (4) [3H]BSTBA photoincorporation into the 150 kDa protein, like saturable [3H]bumetanide binding to intact cells, requires the simultaneous presence of Na+, K+, and Cl- in the medium containing the radiolabelled diuretic.

Affinity Labels↗
PubMed1988

Food intake, neuroendocrine and temperature effects of 8-OHDPAT in the rat.

Administration of 8-hydroxy-2(di-n-propylamino)tetralin (8-OHDPAT) to rats produced dose-dependent decreases in food intake and hypothermia, increases in plasma prolactin and corticosterone, and a decrease in plasma growth hormone. 8-OHDPAT administration also induced the serotonin behavioral syndrome at all doses. Pretreatment with metergoline did not affect the 8-OHDPAT-induced behavioral syndrome or decrease in food intake but attenuated the prolactin increase and, furthermore, potentiated 8-OHDPAT-induced hypothermia. Pretreatment with ritanserin or naloxone did not modify 8-OHDPAT-induced changes in food intake, temperature or prolactin. Similarly, pretreatment with phenoxybenzamine, propranolol, clonidine, haloperidol and methiothepin also did not attenuate 8-OHDPAT-induced decreases in food intake. Administration of pindolol alone produced hyperthermia, decreased food intake and enhanced prolactin secretion. Pindolol thus appears to act as a partial 5-HT agonist in addition to being an antagonist at central 5-HT receptors.

8-Hydroxy-2-(di-n-propylamino)tetralin↗
PubMed1988

Positive inotropic effects of calcium channel antagonists are not necessarily caused by partial calcium channel agonism.

Recently it has been reported that some dihydropyridine calcium channel antagonists (nifedipine, nimodipine, nitrendipine) are able to produce positive inotropic effects in isolated perfused guinea pig hearts. We studied the effects of nifedipine in isolated perfused paced rat hearts under constant pressure and constant flow perfusion conditions. We found that nifedipine is able to produce a positive inotropic effect under constant pressure conditions but not under constant flow conditions. We conclude that nifedipine does not have partial calcium channel agonistic properties and that the positive inotropic effect seen under constant pressure conditions is a result of the vasodilating properties of the drug. Positive inotropic effects caused by vasodilatation can be explained by the "garden-hose-effect".

Animals↗
PubMed1988

Malignant mixed müllerian tumor of the uterus arising in association with a viable gestation.

Malignant mixed müllerian tumors of the uterus are rare neoplasms occurring predominantly in postmenopausal women. We report the prenatal course and diagnosis of a stage III malignant mixed müllerian tumor at cesarean section in a 35-year-old woman. Despite aggressive radiation and chemotherapy, the patient died 14 weeks after diagnosis and initial surgical therapy. The premature infant had an uneventful course.

Adult↗
PubMed1988

cDNA clones from autocrine thymic lymphoma cells encode two mitogenic proteins, a serine protease and a truncated T-cell receptor beta-chain.

Cell lines derived from primary X-ray induced T cell lymphomas (PXTL) of C57BL/6 mice secrete into the medium factor(s) required for their growth. These autocrine factor(s) are distinct from previously described growth factors. cDNA cloning experiments were performed in an attempt to identify these autocrine factor(s). cDNA clones were selected by mRNA size, differential expression, and mitogenic activity of their translation products (Xenopus expression system) on PXTL cells. Two different cDNA clones yielded distinct mitogenic proteins. One clone encodes an altered form of the T cell receptor beta-chain which is truncated at the N-terminus to amino acid 49 of the constant region beta 2. The second clone encodes a serine protease which is identical to factor H or granzyme A from cytotoxic T cells. The 5' portion of the cDNA encoding the serine protease derived from PXTL cells differs from that derived from cytotoxic T cells. This difference results in distinct signal peptides. Unlike cytotoxic T cells, PXTL cells do not store the serine protease intracellularly but secrete it.

Amino Acid Sequence↗