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Biomedical subjects

M Steiner

Publications and source records attributed to M Steiner.

At least 451 records · Page 25Linked to original sources
PubMed1980

Fluorescence microphotometric studies of the transferrin receptor in human erythroid precursor cells.

The receptor site for transferrin in normal human erythroid precursor cells was studied by fluorescence microscopy. F-transferrin saturated with iron was used as probe of the available receptor sites on reticulocytes and nucleated red cells. In a series of experiments specificity and certain structural details of the ligand site were evaluated. Hydrolytic cleavage of exposed carbohydrate moieties by purified glycosidases revealed increased fluorescence after treatment of fixed cells by neuramindase, no perceptible change after N-acetylhexosaminidase treatment, but a pronounced decrease after exposure to beta-galactosidase. Inhibitor studies with monosaccharides and tryptic glycopeptides of normal reticulocytes complemented and amplified the results obtained with enzymes. The data suggest that an oligosaccharide chain is essential for specific transferrin binding to erythroid precursors. N-acetyl-neuraminic acid, galactose, N-acetylgalactosamine, and fucose appear to be saccharides on the receptor. These studies also demonstrate the applicability of fluorescence microscopic methods to qualitative structural analysis of receptor biochemistry.

Binding Sites↗
PubMed1980

Computers in preventive dentistry.

In the course of the past 20 years, an astonishingly rapid development of modern programmable computers has taken place. Electronic data processing (EDP) has therefore become very cheap. EDP may be used in all types of research; however, this paper deals specifically with applications in preventive cariology and periodontology. The use of punch cards and magnetic tape for storing of dental data is discussed. The principle of error testing of dental caries data is exemplified. A simple program which performs DMF counts is presented and explained. Some principles for longitudinal caries studies are elucidated. The use of large computing centres for processing extramural clinical studies is discussed. Some examples of progress due to utilization of EDP systems are given. The advantages of small computers on one hand and of large computers on the other hand are illustrated using the problem of DMF statistics. Some other applications of EDP are mentioned.

Computers↗
PubMed1980

Platelet antibody in idiopathic thrombocytopenic purpura and other thrombocytopenias. A quantitative, sensitive, and rapid assay.

Platelet-associated immunoiglobulin weas measured by the use of fluorescent anti-IgG antibody. The method is simple, rapid, and sensitive and provides a precise quantitative assay of bound (direct) and free (indirect) IgG with platelet specificity. We have evaluated this test in 30 normal volunteers and in 50 patients with immune and nonimmune, treated and untreated thrombocytopenias. All patients with immune thrombocytopenias (acute and chronic idiopathic thrombocytopenic purpura and systemic lupus etythematosus) having platelet counts < 100,000/microliter had elevated levels of platelet-bound IgG, and 86% had also positive results in the indirect assay. All patients with nonimmunological thrombocytopenias showed normal results in the direct and indirect assay of platelet-associated immunoglobulin. In patients studied repeatedly during the course of their illness, an inverse relation was found between platelet count and level of platelet-bound IgG. Patients with systemic lupus erythematosus presented clear exceptions to this rule. Investigations of the absorbability of platelet autoantibodies and alloantibodies showed that this assay can readily differentiate between these two antibody species and can also identify specificities of alloantibodies.

Adolescent↗
PubMed1980

Severe premenstrual tension: delineation of the syndrome.

Forty-two women with severe premenstrual tension syndrome (PMTS) were studied to define the clinical phenomenology and examine its resemblance to common psychiatric disorders. They were mature, adult women suffering severe emotional and physical symptoms in the premestruum but well at other times. Their mean premenstrual score on the Menstrual Distress Questionnaire (MDQ) was twice as high as in the study of Moos. Symptoms showed a marked On--Off phenomenon between premenstrual and follicular evaluations with all rating instruments (p less than 0.001). Existing scales for depression, anxiety, and hostility did not demonstrate that the core disturbance of PMTS is any of these dimensions alone. Item analysis of the MDQ revealed that irritability, mood lability, tension, and restlessness were the most prominent emotional descriptors of this specific syndrome. Several indicators of impaired intellectual and physical functioning were also noted. In most of these women PMTS occurred in the absence of other psychopathology. Subclinical characterological and neurotic disturbances when present were probably exacerbated in the premenstrual period. PMTS is not a clinical model for recurrent affective disorders.

Adult↗
PubMed1980

Platelets as a source of growth-promoting factor(s) for tumor cells.

Human platelet lysate was shown to contain growth-promoting activity for four well-established malignant cell lines. Platelet lysate was able to support their cell proliferation without plasma or serum, indicating that platelets contained "survival factor" as well as mitogenic factor for these tumor cells. The growth-promoting activity was nondialyzable, heat stable up to 56 degrees, and partially trypsin labile, but it was completely destroyed by periodate oxidation, suggesting that a glycoprotein or glycopeptide may be the active principle. The activity was released from platelets aggregated by thrombin or collagen but not by adenosine diphosphate. This suggests that alpha-granules may be the principle storage site for growth-promoting activity.

Animals↗
PubMed1980

Characterization of the platelet-aggregating activity of tumor cells.

Two lines of mouse tumor cells were shown to be capable of aggregating mouse and rabbit platelets in vitro. This process required higher Mg2+ concentrations than were needed by other commonly used platelet-aggregating agents. Platelet-aggregating activity was also found in tumor cell membrane fragments. This membrane-bound platelet-aggregating material contained protein, lipid, and carbohydrate moieties. The presence of all three appeared to be essential for stimulating platelet aggregation. Destruction of any component abolished its activity: protein by trypsin; lipid by phospholipase A2 and non-ionic detergents; and sialic acid by neuraminidase. Platelet aggregation induced by tumor cell membrane fragments was associated with a secretory release reaction. In this process, growth-promoting activity for tumor cells was also released from platelets. These results underline the importance of platelets in establishing tumor metastases.

Adenocarcinoma↗
PubMed1980

Normalization of dexamethasone suppression test: a laboratory index of recovery from endogenous depression.

Carroll et al. reported that an abnormal dexamethasone suppression test (DST) may identify approximately 50% of endogenous depressives and that normalization of the test occurs with clinical recovery. Brown et al. and Schlesser et al. have confirmed the diagnostic utility of the test. A preliminary study suggested that when the DST failed to normalize at discharge, patients were at high risk for early relapse. In this study, we compared ten unipolar or bipolar endogenous depressives who had an abnormal DST on admission and a normal DST at discharge, with four patients whose abnormal DST on admission failed to convert at discharge. On all measures, those whose DST fail to convert showed substantially less improvement. Patients whose DST fail to normalize may have incomplete resolution of their underlying depressive process. Despite clinical judgment that discharge may be appropriate these patients may require further active treatment. Use of the DST prior to discharge may help discriminate between patients whose remaining symptoms reflect situational or psychosocial problems and those with a continuing endogenomorphic process.

Adult↗
PubMed1979

Phosphylation and protein kinase activity of platelet tubulin.

Platelet tubulin isolated by two successive cycles of polymerization-depolymerization was shown to contain protein kinase activity. The phosphorylating activity measured by incorporation of [32P]phosphate from [gamma-32P]ATP was cAMP-independent and behaved with respect to substrate specificity, cation requirement, and maximum incorporation of phosphate similarly to tubulin of brain. Contrary to tubulin from that source, however, platelet tubulin itself, not one of its co-purifying proteins appeared to be the source of the protein kinase activity. This was suggested by assays of tubulin freed from its associated proteins by chromatography on DEAE-Sephadex and on immunosorbent columns containing monospecific antibody to human platelet tubulin. Further corroboration was obtained from experiments in which tubulin was applied to casein affinity columns. No separation of protein kinase from colchicine binding activity could be obtained. Gel filtration showed that all of the in vitro phosphorylated tubulin was aggregated. Tryptic peptide patterns of 32P-labeled alpha- and beta-tubulin subunits were analyzed by ion exchange chromatography. Multiple peptides in both tubulin subunits were identified as acceptors of [32P]phosphate. In vivo phosphorylated tubulin was demonstrated to contain an average of 5 phosphoserine residues/monomer.

Alkaline Phosphatase↗
PubMed1979

Psychobiology of mental disorders associated with childbearing. An overview.

The diagnostic issues, classification, incidence, genetic factors, and theories of etiology of psychiatric illness associated with childbirth are reviewed. Psychologic influences, psychosocial factors and the concept of biologic maladaptation associated with prospective motherhood are discussed. Postpartum mental distress is not a unitary phenomenon. The physiology of the puerperium is thus not a cause in itself of any of the symptoms, but rather must be regarded as a contributing or triggering factor acting upon an underlying predisposition. Clinical research of postpartum psychiatric syndromes (PPS) and animal behavior studies are inconclusive. It is suggested that major neuroendocrine research strategies currently used in studying affective disorders and schizophrenia should be applied in studying PPS.

Adrenal Cortex Hormones↗
PubMed1979

Primary drug resistance in children. Drug susceptibility of strains of Mycobacterium tuberculosis isolated from children during the years 1973 through 1977 at the Kings County Hospital Center of Brooklyn.

A continuing study of the frequency of primary drug resistance among children treated at the Kings County Hospital Center of Brooklyn during the years 1973 through 1977 showed a high incidence of primary drug resistance to isoniazid (8.8 per cent) and to streptomycin (12.3 per cent). In contrast, there were no strains resistant to cycloserine, viomycin, ethambutol, or rifampin, and only one of 57 strains (1.8 per cent) was resistant to ethionamide, and one (1.8 per cent) was resistant to para-aminosalicylic acid. Comparison with previous studies begun in 1961 showed no significant increase in resistance to isoniazid during 3 prior periods of study and no increase in resistance to streptomycin during the last 2 periods of study. It must be emphasized that these findings relate only to the children of a local community, and do not reflect the prevalence of primary drug resistance elsewhere in this country or among different age groups.

Adolescent↗
PubMed1979

Quantitative assessment of polymerized and depolymerized platelet microtubules. Changes caused by aggregating agents.

The equilibrium between assembled and disassembled microtubules was studied in human platelets exposed to aggregating agents. Soluble and insoluble tubulin were "frozen" by addition of a glycerol-dimethyl sulfoxide-containing medium. The two pools were estimated by measuring the colchicine binding activities of total and polymerized tubulin. Resting platelets were found to contain an average of 56.2 mug tubulin/1 x 10(9) cells of which 56.7% was in polymerized form. Platelet aggregation induced by thrombin, ADP, epinephrine, or collagen produced a transient decrease in the pool of polymerized tubulin which was evident within 15 s after addition of the aggregating agent. A return to base-line values occurred within 1-4 min depending upon the specific aggregating agent used. Neither secretory release nor aggregation of platelets were found to be prerequisites for the temporary disturbance of the equilibrium between soluble and polymerized tubulin. With thrombin as the aggregating agent a clear threshold concentration could be demonstrated above with a dose-dependent dissociation response of microtubules was evident. We conclude that microtubules exist in a dynamic equilibrium between polymerized and depolymerized forms in human platelets, which is transiently disturbed by their interaction with aggregating agents.

Blood Platelets↗