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Biomedical subjects

M Steiner

Publications and source records attributed to M Steiner.

At least 397 records · Page 22Linked to original sources
PubMed1983

Effect of alpha-tocopherol administration on platelet function in man.

The effect of vitamin E administration on platelet function was evaluated in a group of normal, healthy volunteers. Platelet aggregation induced by collagen, ADP and epinephrine and platelet adhesion to collagen were measured at weekly intervals in 20 men and 27 women divided into 3 experimental groups of 12 individuals each and one control group of 5 men and 6 women. One experimental group was on a 6-week regimen of vitamin E in increasing dosages (400 I. U.--1,200 I. U.), the second group received aspirin, 300 mg every other day, and the third group was on a combination of vitamin E and aspirin. In the control group, platelet function was measured at weekly intervals. In women, vitamin E by itself produced a small but significant reduction of collagen-induced platelet aggregation. A similar trend was seen in men. However, the reduction never reached statistical significance. Adhesiveness to collagen was not affected by aspirin ingestion but showed a highly significant reduction in vitamin E and vitamin E + aspirin treated individuals. These results suggest that vitamin E administration could have a beneficial effect in patients suffering from arterial thromboembolic diseases.

Adult↗
PubMed1983

Membrane-bound tubulin in human platelets.

Platelet membranes contain colchicine-binding activity which is not due to cytoplasmic contamination. This activity could be solubilized, at least partially, by Triton X-100 and to a lesser degree by Lubrol PX. Nonidet P-40 solubilized more colchicine-binding activity than was apparent in the intact, non-detergent-treated membranes, indicating that some of the protein was available for binding in the latter. Normal membranes had a far higher binding capacity for the alkaloid vinblastine than for colchicine, both of which were measured under equilibrium conditions. Membrane tubulin was also identified by acrylamide gel electrophoresis and immunologic precipitation. The protein had characteristics similar to the cytoplasmic form but was found to be more heat resistant. These findings establish with a high degree of certainty the presence of tubulin in the platelet membrane.

Binding Sites↗
PubMed1983

Purulent mediastinal abscess secondary to Ludwig's angina.

A case of Ludwig's angina dissected along deep cervical fascial planes into the mediastinum caused a virulent mediastinitis and abscess. Computed tomography precisely delineated the extent of the infection. Incomplete débridement resulted in a residual abscess and persistent systemic sepsis that culminated in the patient's death. Aggressive antibiotic treatment of the orofacial cellulitis along with complete mediastinal drainage are recommended for optimal outcome.

Abscess↗
PubMed1983

Isolation and properties of the native chromoprotein halorhodopsin.

The native chromoprotein of the light-driven chloride pump halorhodopsin (HR) was isolated from Halobacterium halobium strain L-33 which lacks bacteriorhodopsin but contains 'slow cycling rhodopsin-like pigment' (SR). A membrane fraction was prepared in low salt and dissolved in a high salt medium by the detergents Lubrol PX or octylglucoside. These conditions destroyed the chromophore of SR but not the HR pigment. Chromatography on phenyl-Sepharose and hydroxylapatite produced, in 60% yield, a 230-fold enriched monomeric chromoprotein with an apparent mol. wt. of 20,000. The chromoprotein was stable in 1 M NaCl and 1% octylglucoside and remained stable upon removal of detergent. It reacted with borohydride in the dark and with hydroxylamine in the light. The absorption maximum of the light-adapted state is at 580 + 2 nm and its molar extinction approximately 50,000/M/cm. Upon illumination in the presence of detergent it was converted into a 410 nm absorbing species with concomitant release of protons. A thermal reconversion to the 580 nm species occurred with a half time of 76 s at -6 degrees C. Blue light absorbed by the photoproduct accelerated the re-conversion as well as the re-uptake of protons. Removal of the detergent prevented the light-induced formation of the 410 nm species. Under these conditions a photochemical behaviour similar to that in intact cells and cell vesicles, i.e., a photocycle in the 10-20 ms range was observed. These findings form the basis for functional reconstitution of HR.

Bacteriorhodopsins↗
PubMed1983

The differentiation of malignant lymphoma from anaplastic seminoma in a patient presenting with testicular and jaw swelling.

The histologic differentiation of anaplastic seminoma from lymphoma is often difficult. In the case presented, a malignant lymphoma showing prominent testicular and jaw involvement was initially interpreted as seminoma. The histologic and ultrastructural criteria for differentiation, as well as a comparison of the clinical and epidemiologic characteristics of these tumors, are discussed. A reassessment of previously reported cases of seminoma metastatic to the jaws/antrum, made relative to these data, suggests that in most cases the tumors may actually be lymphomas.

Diagnosis, Differential↗
PubMed1983

Biochemical interaction of arachidonic acid and vitamin E in human platelets.

The effect of alpha-tocopherol on the oxidative transformation of arachidonic acid was investigated in human platelets. The major products of lipoxygenase and cyclo-oxygenase pathways were separated by high performance liquid chromatography (HPLC) and thin layer chromatography (TLC) evaluated by scanning the radiochromatograms. This study differs from others in the vitamin E field in important aspects of its experimental design: the prelabeling of platelets with non-aggregating concentrations of 14C-arachidonic acid, and the addition of alpha-tocopherol as a colloidal suspension rather than as an ethanolic solution. A moderately potent but consistent reduction of apparent cyclo-oxygenase activity by alpha-tocopherol could be demonstrated by TLC and HPLC. This effect was best shown by the change of the HETE/HHT ratio which increased significantly in vitamin E-treated platelets. It was found to be dose-dependent up to 1 microM alpha-tocopherol, the maximal concentration tested in this study. Alpha-tocopherol quinone was equally effective in this action.

Arachidonate Lipoxygenases↗
PubMed1983

Effect of eicosatetraenyl (3-aminopropyl) phosphonate (URI-73A) on platelet aggregation and arachidonic acid metabolism.

Eicosatetraenyl (3-aminopropyl) phosphonate (URI-73A), an experimental anti-hypertensive drug, when tested in vitro, inhibits platelet aggregation especially that induced by arachidonic acid (AA) and to a lesser degree by epinephrine. Preincubation of human platelets with this compound in the majority of individuals resulted in a dose-dependent inhibition of the platelet response to AA, mostly in the form of a delay and a reduction of maximal aggregation. Platelets from two smaller groups of donors either exhibited full aggregation or no aggregation. Both the prelabel and pulse label techniques used to study arachidonic acid metabolism yielded complementary results. Production of thromboxane and hydroxy fatty acids was reduced in thrombin-aggregated washed platelets preincubated with URI-73A. In addition, the release of AA from phospholipids was inhibited. Its complex effects on human platelets suggest that URI-73A may, as an AA analog, depress cyclooxygenase and lipoxygenase, and as a phospholipid analog inhibit phospholipase activity.

Adenosine Diphosphate↗
PubMed1983

A continuing study of primary drug-resistant tuberculosis among children observed at the Kings County Hospital Medical Center between the years 1961 and 1980.

A 20-yr prospective study of the incidence of primary drug-resistant tuberculosis among children treated at the Kings County Medical Center was undertaken in January 1961 and extended through December 1980. There were 355 strains of Mycobacterium tuberculosis isolated during this time, 56 of which were found to be primarily resistant to one or more antituberculosis drugs, giving an overall resistance rate of 15.8%. The study was divided into five 4-yr periods. The resistance rate to isoniazid was 9.9%, varying from a peak of 15.2% in the third period of study (1969 to 1972) to 4.5% in the last period of study. The changes in the rate were not significant. The overall resistance rate for streptomycin was 9.2%. There were significant increases in the resistance rate in the second (1965 to 1968) and third (1969 to 1972) periods of study, but not in the last 2 periods. The rates for PAS (3.4%), rifampin (1%), and ethambutol (0.7%) were low. The type and severity of disease among those infected with a resistant strain were no different from those infected with a susceptible strain. Life-threatening disease was found in 10 of the 56 patients infected with a drug-resistant strain. There was one fatality in a child with meningitis who was treated early in the study. Our experience suggests that rifampin and ethambutol be included in the initial treatment regimen of all children with a life-threatening form of tuberculosis until the susceptibility pattern of the infecting strain is determined, after which the drug regimen can be modified if necessary.

Aminosalicylic Acid↗
PubMed1982

Inhibition of thrombin-neutralizing activity of antithrombin III by steroid hormones.

Estrogens in high doses have been shown to inhibit, in vitro, the thrombin-neutralizing action of antithrombin III (AT III). In this study we investigate the effect of estrogens on AT III in greater detail. To increase the sensitivity of measurement of AT III activity in the absence of heparin, we have developed an assay system utilizing human platelets, AT III and thrombin. The two proteins derived from human plasma were prepared in high purity. Platelet aggregation was induced by approximately 0.02 NIH U of thrombin. AT III was added in amounts that suppressed 95% of the aggregation-inducing effect of thrombin. Estrogens blocked the thrombin-neutralizing effect of AT III in dose-dependent manner. This effect was shown to be specific for AT III. Neither aggregability of platelets nor aggregating effect of thrombin were affected by the steroid hormone. Evidence for binding of estrogen to AT III was obtained from changes in intrinsic fluorescence of AT III. ACtivity of AT III was also reduced in increasing order of effectiveness by cholesterol, cortisone, testosterone and progesterone. Our studies suggest a direct effect of estrogens and other steroids on AT III, altering its specific neutralization of thrombin.

Antithrombin III↗
PubMed1982

Isolation and characterization of the retinal-binding component of halorhodopsin.

Halorhodopsin (HR) was reconstituted in cell vesicles prepared from Halobacterium halobium strain L-07 by addition of tritium-labelled retinal and subsequently reduced with cyanoborohydride. Lysis of the labelled vesicles in water and dissolution of the cell membranes with 4% SDS allowed the purification of the retinyl protein (RP) by a 3-step procedure. Gel filtration on AcA-44 ultrogel was followed by chromatography on hydroxylapatite and preparative SDS-polyacrylamide gel electrophoresis. This procedure yielded material which migrated as a single band of an apparent mol. wt. of 25 000 on analytical SDS-polyacrylamide gels. The purification was 400-fold with an overall yield of 15%. Not only the mol. wts. but also the amino acid compositions of the RPs from bacteriorhodopsin (BR) and HR are very similar. Polyclonal antibodies against BR and HR did not, however, crossreact. When the two RPs were partially digested with staphylococcal V8 protease the proteolytic pattern of the retinyl peptides was similar, but not identical: two extra peptides are present in BR. The same kind of differences were found in the h.p.l.c. elution profiles of retinyl peptides produced by subtilisin digestion. Therefore, the two proteins must be different gene products and not modification products of one and the same protein.

Journal Article↗
PubMed1982

BCG-induced orchitis: structural changes during the degeneration of seminiferous tubules of rats and rabbits.

The effect of BCG-induced orchitis on the structure of the seminiferous tubules in rats and rabbits was investigated by light and electron microscopy. The formation of cavities between Sertoli cells and the displacement of the cells of the spermatogenic cycle are the earliest changes to be observed. Individual Sertoli cells and the displacement of the cells of the spermatogenic cycle are the earliest changes to be observed. Individual Sertoli cells degenerate and separate from spermatocytes and spermatids. The latter form multinuclear complexes by a broadening of the intercellular bridges. The nuclei of spermatids undergo ring-like chromatin condensation in the rat and swelling in the rabbit. After the loss of spermatocytes and spermatids from the germinal epithelium, the remaining Sertoli cells have a very irregular shape and contain many residual bodies, which are probably derived from previously phagocytosed spermatids. They often contain crystalline inclusions. The nuclei of Sertoli cells show small chromatin condensations. In the rabbit, the tubular wall increases considerably in diameter. In the vicinity of a granuloma in the interstitium caused by BCG inflammatory cells accumulate around the wall of the seminiferous tubules. Although the basal lamina seems to be an obstacle, penetration of macrophages into the tubular lumen could be observed. However, this occurred only after the degeneration of the germinal epithelium.

Animals↗
PubMed1982

Biomechanics of tendon healing.

The biomechanics of tendon healing was investigated with unsutured rat achilles tendons. After two, three, and four weeks of healing tensile parameters were assayed with a bone-muscle-tendon-bone preparation elongated to failure at a controlled physiological strain rate. In the third week of healing, stiffness, strength, and energy absorbing capacity all increased approximately 50%. These changes correlated with early fibroplasia. In the fourth week of healing, strength, energy absorbing capacity and elongation to failure all increased relatively more than stiffness. Histologically, larger fibers with better longitudinal alignment developed during this period. At the end of four weeks the tendon's strength was approximately 25% of normal. To summarize, the return of stiffness in a healing tendon preparation correlated with the presence of fibroplasia and the return of other tensile parameters was a function of the amount and organization of the fibroplasia.

Achilles Tendon↗