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Biomedical subjects

M Steiner

Publications and source records attributed to M Steiner.

At least 487 records · Page 27Linked to original sources
PubMed1976

Isolation of platelet microtubule protein by an immunosorptive method.

A rapid and highly specific method for the isolation of human platelet tubulin by immunosorption was developed. Platelet tubulin isolated by successive cycles of polymerization was used as antigen. Densitometric quantification of the antigen subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed 96% tubulin of molecular weight 55,000 and 4% high molecular weight proteins (mr = 240,000 to 250,000) which co-purified with platelet micrtobule protein. Platelet tubulin bound 0.57 mumol of colchicine/100 mg of protein. Monospecific antibody of human platelet tubulin was prepared in rabbits. After absorption with tubulin co-purifying high molecular weight proteins, and serum proteins, the rabbit anti-tubulin serum gave a single precipitin line on double immunodiffusion against platelet tubulin and the high speed supernatant of a platelet sonicate (platelet extract). The antiserum precipitated the colchicine-binding activity of platelet extracts. The gamma-globulin fraction of the absorbed antiserum was linked to an agarose matrix. Platelet extracts applied to such immunosorptive columns showed the disappearance of a single protein which was eluted with 0.5 g/liter of Triton X-100 and identified as platelet tubulin. Its colchicine-binding activity was retained in full. Electron microscopic examination revealed that the ability of platelet tubulin to polymerize and form tubules was not impaired in the presence of 0.5 g/liter of Triton X-100. This simple isolation procedure of platelet tubulin has great advantages in terms of purity and yield and can readily be adapted for use with other cell systems.

Binding Sites↗
PubMed1976

Effect of thrombin on phosphorylation of platelet membrane proteins.

The effect of thrombin on the phosphorylating activity of platelet membranes was compared to that of trypsin. Preincubation of non-32P phosphorylated platelet membranes with or without either of these two enzymes resulted in a considerable loss of membrane protein kinase activity which was most severe when trypsin was used. Protein kinase activity and endogenous protein acceptors decreased in parallel. 32P-phosphorylated membranes showed a slow but progressive loss of label which was accelerated by trypsin. Thrombin under these conditions prevented the loss of 32P-phosphate. These results are interpreted to indicate a thrombin-induced destruction of a phosphoprotein phosphatase. The protein kinase activity of phosphorylated platelet membranes using endogenous or exogenous protein substrates showed a significant reduction compared to non-phosphorylated membranes suggesting a deactivation of protein kinase by phosphorylation of platelet membranes. Neither thrombin nor trypsin caused a qualitative change in the membrane polypeptides accepting 32P-phosphate but resulted in quantitative alterations of their ability to become phosphorylated.

Blood Platelets↗
PubMed1976

Distribution of free sulfhydryl and disulfide groups among platelet membrane proteins.

Reactive sulfhydryl and disulfide groups were identified in platelet membrane proteins resolved by sodium dodecyl sulfate-polycrylamide gel electrophoresis. Platelet membranes treated with N-ethyl(1-14C)maleimide, phenyl(203Hg)mercuric acetate and p-chloro(203Hg)mercuribenzoate showed similar patterns of distribution of sulfhydryl groups among the sodium dodecyl sulfate-solubilized membrane proteins. Four major and two minor polypeptides ranging in molecular weight from greater than 200 000 to 20 000 were found to have reactive SH groups. Reduction of membrane proteins by sulfite coupled with subsequent mercaptide formation of the resultant monothiols led to the identification of four polypeptides with disulfide bonds. Reaction of platelet membranes with 14C-labeled 5,5'-dithio-bis(2-nitrobenzoic acid) resulted changes in the distribution profile of the solubilized membrane proteins suggestive of a polymerization process dependent upon, 5,5'-dithio-bis(2-nitrobenzoic acid)-induced intermolecular disulfide interchange.

Binding Sites↗
PubMed1976

Vitamin E. An inhibitor of the platelet release reaction.

Formation of lipid peroxides rises sharply when platelets undergo the release reaction. In this study the in vitro effect of vitamin E on platelet aggregation was investigated. alpha-Tocopherol, an anitoxidant of known inhibitory action on lipid peroxidation, was added to platelet suspensions in concentrations up to 1.5 mM. A dose-dependent reduction in platelet aggregation was observed, with complete inhibition of the secondary wave of aggregation at greater than or equal to 0.9 mM alpha-tocopherol. The inhibitory effect of alpha-tocopherol on the platelet release reaction was further documented by the decrease in aggregation-induced release of [14C]5-hydroxytryptamine from prelabeled platelets and by the reduction of N-acetylglucosaminidase activity released into the medium. The sharp rise in lipid peroxides normally associated with platelet aggregation was markedly reduced by alpha-tocopherol and also by acetylsalicylic acid, a known inhibitor of the platelet release reaction. In vivo studies examined the effect of oral vitamin E administration (1,200-2,400 IU daily) on plasma and platelet levels of alpha-tocopherol. Up to 1,800 IU daily, increasing dosages of vitamin E resulted in increasing concentrations of alpha-tocopherol in plasma and platelets, but intake of vitamin E in excess of this dosage failed to show any further increase in plasma or platelet levels.

Acetylglucosaminidase↗
PubMed1976

Transport kinetics for the uptake of (3H)glycine and (3H)L-glutamate into dorsal and ventral slices of rat spinal cord.

The uptake of [3H]glycine and [3H]L-glutamate into slices of the dorsal and ventral halves of rat spinal cord taken from the thoracal (T3-9) and lumbar (L1-6) regions was determined in the concentration range 2 - 1 000muM. For both amino acids and in all four tissue pieces (thoracal dorsal and ventral, lumbar dorsal and ventral) biphasic linear regressions were obtained from the Lineweaver-Burk plots, demonstrating saturable transport mechanisms both in the high-affinity and in the low-affinity range. No significant dorsal-ventral or lumbar-thoracal differences were found for the transport constants Km of both amino acids. For the maximum velocity V similar dorsal-ventral and lumbar-thoracal gradients were found for both glycine and L-glutamate. These results, which are not entirely in agreement with the distribution of the endogenous pools of these amino acids, are critically discussed in view of the proposed function of high affinity uptake at the synapse.

Animals↗
PubMed1976

An extractable nuclear antigen not attaching to tannic acid-treated erythrocytes.

One of the antigens present in isotonic phosphate buffer extract of calf thymus nuclei against which antibodies are produced in collagen diseases, was shown not to attach to tanned sheep erythrocytes. It is, however, well exposed on slides coated with smears of ENA-extract and fixed with methanol-acetone. Reactions with the antigen can be demonstrated by the mixed haemadsorption technique. Preliminary results suggest that it may be a ribonucloprotein closely related to the 'soluble ribonucleoprotein" (sRNP) attachable to tanned erythrocytes. It may also have a similar relationship to clinical symptoms.

Animals↗
PubMed1975

Chronic eosinophilic pneumonia in a one-year-old child.

Although the literature well describes chronic eosinophilic pneumonia in the adult, there are no reports of this entity in the pediatric age group. We describe a child with chronic eosinophilic pneumonia, emphasizing the specific radiologic features, common conditions in the differential diagnosis, and dramatic response in corticosteroid administration, which is a unique feature of this entity.

Adrenal Cortex Hormones↗
PubMed1974

Human leukemia-associated anti-nuclear reactivity.

A brilliant, coarsely granular nuclear antigen was detected by anti-complement immunofluorescence in the nuclei of acute myeloid leukemia myeloblasts. Designated as LANA (leukemia-associated nuclear antigen), the reactivity differs from that of the Epstein-Barr-virus-determined nuclear antigen (EBNA) in immunological specificity and morphological appearance, although it is visualized by the same method. Serum from acute myeloid leukemia patients gave positive reactions in 73% of the cases. In acute lymphatic leukemia, chronic myeloid leukemia, chronic lymphatic leukemia, and Burkitt's lymphoma the sera were positive in 35, 14, 19, and 24%, respectively. Two of five polycythemia and two of eleven myeloma sera were also positive. Among 61 healthy controls, 58 were negative, whereas three showed a diffuse nuclear staining with a different pattern. Among 24 carcinoma patients, 18 were negative, whereas six gave a nuclear staining with a different, diffuse pattern. Sera from 20 patients who had recovered from infectious mononucleosis were all negative. In addition to the blasts of acute myeloid leukemia, a similar reactivity was seen with two Epstein-Barr virus DNA and EBNA-negative African lymphoma biopsies and in a short-lived tissue culture line derived from one of them. LANA could be a fetal or tissue-specific antigen, a virally determined antigen, or a specific form of anti-nuclear reactivity.

Antibodies, Antinuclear↗
PubMed1974

Direct method for continuous determination of iron oxidation by autotrophic bacteria.

A method for direct, continuous determination of ferric ions produced in autotrophic iron oxidation, which depends upon the measurement of ferric ion absorbance at 304 nm, is described. The use of initial rates is shown to compensate for such changes in extinction during oxidation, which are due to dependence of the extinction coefficient on the ratio of complexing anions to ferric ions. A graphical method and a computer method are given for determination of absolute ferric ion concentration, at any time interval, in reaction mixtures containing Thiobacillus ferrooxidans and ferrous ions at known levels of SO(4) (2+) and hydrogen ion concentrations. Some examples are discussed of the applicability of these methods to study of the rates of ferrous ion oxidation related to sulfate concentration.

Hydrogen Peroxide↗