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Biomedical subjects

M Steiner

Publications and source records attributed to M Steiner.

At least 19 recordsLinked to original sources
PubMed1992

Embryonic development of the CNS microvasculature in the mouse: new insights into the structural mechanisms of early angiogenesis.

Vascularization and expression of blood-brain barrier (bbb) associated morphological characteristics were studied by ultrastructural analysis during the embryonic development of the mouse CNS. At day 9 (E9) capillaries were only found in the perineural mesenchymal tissue exhibiting fenestrations and loosely attached pericytes. At E10 endothelial cells (EC) together with pericytes and other mesenchymal cells invaded the intraneural domain. The immigrating EC showed numerous protrusions and lost their fenestrations as soon as the new intraneural capillaries were formed. Intraneural EC showed prominent nuclei, many pinocytotic vesicles and junctional complexes which appeared tight in some places. These results indicate that from the first day of intraneural vascularization onwards, the morphological properties of the bbb are present in the early embryonic mouse cerebral cortex.

Animals↗
PubMed1992

Radiosurgery.

Explore the source record for details and available documents.

Adolescent↗
PubMed1992

Study to determine the correlation between condom breakage in human use and laboratory test results.

The present study examined the value of laboratory tests in predicting condom breakage for 20 lots of latex condoms which differed in age, storage history and laboratory test performance. Two-hundred-sixty-two participating U.S. couples used a total of 4589 latex condoms (mean = 229 condoms per lot, range 224-235). Breakage rates ranged from 3.5 percent for a brand new condom lot to 18.6 percent for a lot that was 81 months old at the time of the study. The statistical predictor models, separately using ultimate elongation from the tensile test, the Condom Quality Index from the airburst volume test, and the percent of condoms failing the airburst volume test as the independent variables and the condom breakage rate as the dependent variable, all appear to have a high level of accuracy in predicting condom breakage in use. The three models had correlation coefficients (R2s) of 0.81, 0.74 and 0.69, respectively. Perhaps the most unexpected result was that the age of the condom lot was the best predictor of condom breakage during use (correlation coefficient (R2) = 0.92). Although the present investigation does not provide sufficient justification to use age as the only factor for decisions on condom lot disposition, it does provide some guidance.

Adult↗
PubMed1992

Platelet alpha 2-adrenergic receptors in depressed patients and healthy volunteers: the effects of desipramine.

Binding parameters (Bmax and Kd) of alpha 2-adrenergic receptors were studied in platelets from 14 depressed patients and 18 control subjects. Using 3H-clonidine (a partial alpha 2-adrenergic agonist) as the ligand and membranes, prepared from platelets isolated under physiological conditions, we found no significant differences in Bmax and Kd between medication free patients and control subjects. Platelet binding parameters in the depressed patients did not correlate with plasma levels of norepinephrine, epinephrine or MHPG. Age had a significant positive effect on platelet alpha 2-adrenergic receptor Bmax in both groups, and may have masked the patient-control differences. Treatment with desipramine for 28 days had no effect on the binding parameters in depressed patients when compared to pretreatment values. Adding desipramine to platelets of control subjects 'in vitro' did also not affect binding parameters. Our findings suggest that receptor binding studies with a partial alpha 2-adrenergic agonist in platelet membranes are not a useful model to test the hypothesis of a central supersensitive adrenergic system in depression.

Analysis of Variance↗
PubMed1992

Female-specific mood disorders.

Hormones are partial determinants of certain sexually dimorphic behaviors and interact with psychosocial, environmental, and other physiologic factors. The part played by sex hormones in the direct control of overt human behavior is, compared with that found in lower animals, slight and less readily definable. In humans, these hormones, although necessary for maintenance of libido and sexual behavior, seem to control the intensity of such behavior rather than its direction. In most women of reproductive age, the different phases of the menstrual cycle are not associated with major physical or psychologic discomfort. Some women actually report positive changes during the premenstrual period. Only 5-10% of women in this age group have changes in mood, sleep, eating habits, level of energy, and physical symptoms that appear to be linked temporally to the late-luteal phase of the cycle. It is plausible to assume that women with LLPDD are vulnerable to the menstrual cycle as a Zeitgeber. In these women, a cascade of events triggered originally along the HPG axis brings about the shift from an existing vulnerability to the actual manifestations of LLPDD and other forms of female-specific mood disorders. The degree of vulnerability becomes apparent at puberty when girls are exposed to increasing estrogenic influences. Particularly vulnerable times are the periods that mark shifts in the reproductive stages (menarche, the premenstruum, puerperium, and menopause), periods associated with major hormonal turmoil and psychosocial stresses. A conditioning-sensitization model has been described to explain the longitudinal course of affective disorders, and it also has been proposed for PMS. According to this model, even low levels of psychosocial stress are capable of triggering episodes of dysphoria in vulnerable previously sensitized subjects. LLPDD is associated strongly with a lifetime diagnosis of major depression, and the concurrent comorbidity in these women is also high. Future epidemiologic studies on depression should consider the effects of female-specific Zeitgeber on mood disorders in the populations studied.

Female↗
PubMed1992

Dental predictors of high caries increment in children.

A comprehensive set of dental variables was investigated to find the "best" combination of predictors for high caries increment in 7/8-year-old and 10/11-year-old children. Four populations with widely different caries prevalence were studied. Logistic regression analysis supplied multiple-input models by stepwise selection of predictors. A "low number of sound primary molars" was the best and most consistent predictor of high caries increment. The second best predictors were "high numbers of pre-cavity lesions on permanent first molars" (discolored pits and fissures in the younger age group and white spots on the smooth parts of buccolingual surfaces in the older age group). Inclusion of radiological variables did not substantially increase the quality of prediction. For practical application, models with various multiple inputs selected by stepwise procedures were compared with "fixed" three-input models. These three-input models resulted in predictive quality nearly equal to those of the multiple models. Traditional one-input models, containing DMFT or dmft, were inferior to the three-input models, particularly in the older age class. The lower the caries prevalence of the source data, the better was the prediction. As a summary measure characterizing the predictive performance of a model, we used the index "area under the receiver operating characteristic curve" A. For the 1984 data and the three-input models, the area was approximately 80%, and for the 1972 data, the area was 65-70%.

Age Factors↗
PubMed1992

Depression in elderly persons and its correlates in family practice: a Canadian study.

Depression was studied in a Canadian community sample of 582 men and 906 women over the age of 65 years. The Center for Epidemiological Studies Depression Scale (CES-D) provided the measure of depressive symptomatology. The Diagnostic Interview Schedule was used to confirm clinical diagnosis. A total of 8% of the sample (4.3% of men and 10.4% of women) were at or above the cut-off point of 16 on the Depression Scale. Significant Pearson correlations with depression were found for gender and education. The married and never married persons showed low depression while the widowed, separated, or divorced appeared to be at high risk. The relationship of marital status to depression is primarily a woman's issue as most elderly men are married. This finding may have implications for policy and program planning for this population.

Aged↗
PubMed1992

Clinical outcome of radiosurgery for cerebral arteriovenous malformations.

The clinical outcomes are described for 247 consecutive cases of arteriovenous malformation (AVM) treated with the gamma knife between April, 1970, and December 31, 1983. Headache resolved in 65 (66.3%) of the 98 patients presenting with this symptom and improved in an additional nine (9.2%). Of 59 patients admitted with seizures, 11 (18.6%) became seizure-free without anticonvulsant medication and an additional 30 patients (50.8%) became seizure-free with anticonvulsant medication. Pre-existing neurological deficits improved or totally disappeared following radiosurgery in 56.7% of affected cases. This improvement presumably occurred within the frame of the natural history. The protective effect of the ionizing beams against hemorrhage in incompletely obliterated AVM's is analyzed. To assess the rate of rebleeding, probability estimates were calculated using both the person-year method and the Kaplan-Meier life table. With the person-year method the actual rebleed rate is not too different from the values observed in the natural history of the disease (2% to 3%/yr). Analysis by Kaplan-Meier life-table estimates demonstrated a risk of nearly 3.7%/yr until 60 months after radiosurgery. Five years following treatment, the life table ends in a plateau which could be interpreted as an indication of decrease in the risk of hemorrhage. However, long flat regions at the right end of the life table do not imply that the real risk of rebleeding is negligible unless a large number of patients have been followed well into or beyond the flat region.

Cerebral Hemorrhage↗
PubMed1992

Alpha-tocopherol: a potent inhibitor of platelet adhesion.

Administration of vitamin E in doses of 400 IU/day exerts a potent inhibition of platelet adhesion as measured in a laminar flow chamber. Adhesion to all surfaces tested was reduced and appeared to be related to a limited pseudopodia formation in alpha-tocopherol-enriched platelets.

Adult↗
PubMed1992

Applying psychometric criteria to functional assessment in medical rehabilitation: III. Construct validity and predicting level of care.

A discriminant analysis was performed using Rasch ability estimates derived from four Patient Evaluation and Conference System (PECS) subscales, to distinguish among the functional independence and impairment profiles exhibited by patients admitted into any of three levels of medical rehabilitation delineated by the National Association of Rehabilitation Facilities (NARF): (1) inpatient hospital, (2) atypical nursing home (intermediate), or (3) day program. Two discriminant functions accounted for 91% and 9% of the between-group variance, respectively. Cross-validated classification of patients into one of the three levels of care, based on discriminant function scores, produced 75% correct classification; a 66% improvement over the percentage of correct classification likely by chance alone. Results support the construct validity of the PECS subscales and indicate they may be useful in validating clinically-based admission decisions among three of the levels of care promulgated by NARF.

Activities of Daily Living↗
PubMed1992

[Caries prevention among the schoolchildren of Wil, SG 1963 to 1990 and the caries statistical results].

In 1963, a school-based preventive programme was organized in the community of Wil. Supervised toothbrushing with fluoride preparations 12 times per year was coordinated with an improvement of the quality of the between-meal snacks. In 1979, 1985 and 1990 fourteen-year-old pupils were dentally examined in Wil. There was a caries decrease between 1979 and 1985 as well as between 1985 and 1990, after the daily distribution of fluoride tablets was stopped in 1983 and the fluoride content of salt raised from 0.009 to 0.025%. Between 1979 and 1985 the fourteen-year-olds of Wil had fewer lesions than the pupils of Zurich and Glarus and between 1987 and 1990 caries prevalence in pupils of this age in the three areas mentioned ranged between 2.2 to 3.4 DMFT. In 1990 caries prevalence at the ages of 8 and 12 was also assessed in Wil. Prevalence levels were as low as in the cantons of Zurich (organized prevention at school since 1964) and Glarus (fluoridated salt, 250 ppm F, for households and bakeries since 1976) in 1987/88.

Adolescent↗
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↗