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Biomedical subjects

D Smith

Publications and source records attributed to D Smith.

At least 865 records · Page 48Linked to original sources

Uniform field flicker: masking and facilitation.

The influence of uniform field flicker (UFF) on the contrast threshold for stationary sinusoidal gratings was measured as a function of flicker depth. Changing from no flicker to a flicker depth of 10% produces reliable differences in threshold. Further increases in flicker depth to 60% had little additional influence. The presence of UFF produces masking with low spatial frequency stimuli as expected but at higher spatial frequencies facilitation is obtained. The results are discussed in the context of the distinction between primate Magnocellular and Parvocellular pathways.

Adult↗

In vivo method for the assessment of platelet accumulation.

Platelets labeled with 111Indium have been injected intravenously into anesthetised guinea pigs, and intrathoracic content of 111Indium-labeled platelets has been monitored continuously using a microcomputer-based system (AIMSplus). Dose-effect relationships have been described for ADP, collagen, and PAF, and effects of drugs upon selected responses illustrate the potential of this test system for routine in vivo screening of agents that may inhibit aggregation of platelets.

Adenosine Diphosphate↗

Homodigital neurovascular island flaps for digital pulp loss.

Terminal amputations with loss of the distal pulp are common injuries. This report analyses 64 consecutive cases of advanced or exchanged homodigital neurovascular island flaps operated on by one surgeon between 1981-1986. The surgical technique, indications, contra-indications and five year results are evaluated. Overall, these flaps provide reliable vascularity as well as normal sensibility at the distal end of the finger where high quality perception is required.

Adolescent↗

Blood coagulation profile in long-term hormone replacement therapy with mestranol.

The coagulation profile of oophorectomised women on long-term (15 yr) hormone replacement therapy with mestranol (30 micrograms/day) is compared to that of women on long-term placebo. Analysis of these data showed no significant difference in prothrombin time, partial thromboplastin time or in anti-thrombin III level in these groups.

Adult↗

Regional and physical mapping studies characterizing the Greig polysyndactyly 3;7 chromosome translocation, t(3;7)(p21.1;p13).

The Greig polysyndactyly-craniofacial anomalies syndrome is an autosomal dominant disorder involving a gene(s) located in band 7p13. We have isolated and characterized a reciprocal 3;7 chromosome translocation that resulted in the syndrome. We have identified two closely linked (0 cM) conserved DNA sequences (P137/p944B) that flank the translocation breakpoint. A pulsed-filed analysis combined with available genetic linkage information demonstrates that the disorder is linked (2 cM) to the T-gamma receptor locus, lending considerable support to the hypothesis that the mouse mutant extra-toes is the counterpart of the Greig syndrome. We have found no evidence that physically links the EGF receptor to the P137/p944B region, again compatible with mouse linkage relationships. The isolation of the der(3) chromosome from the 3;7 translocation has allowed us to regionally localize probes within the 3p21.1 band. For three probes commonly used in heterozygosity experiments with human cancers involving chromosome 3, we have determined that the order from centromere to telomere is D3S3, D3S2, and DNF15S2. Our pulsed-field studies also demonstrate the utility of band density differences combined with partial digests in evaluating linkage relationships. The P137/p944B probes should be useful in examining other hereditary disorders with phenotypic similarities to the Greig syndrome.

Animals↗

The Complex Carbohydrate Structure Database.

The Complex Carbohydrate Structure Database (CCSD) and CarbBank, an IBM PC/AT (or compatible) database management system, were created to provide an information system to meet the needs of people interested in carbohydrate science. The CCSD, which presently contains more than 2000 citations, is expected to double in size in the next two years and to include, soon thereafter, all of the published structures of carbohydrates larger than disaccharides.

Carbohydrates↗

tRNA-tRNA interactions within cellular ribosomes.

We describe an assay that converts the effects of tRNA-tRNA contacts at two particular codons into a quantitative effect on beta-galactosidase level. The assay measures the separate and combined efficiency of suppression at adjacent nonsense codons in vivo using a set of specially created homologous messages. In a survey of distal anticodon arm substitutions, we find that particular mutant tRNAs occupying the P-site reduce the apparent efficiency of the suppressor tRNA reading the A-site codon by factors of 2-170. By using measured tRNA-tRNA distances and the crystallographic tRNA structure, we propose a model of the tRNA-tRNA-mRNA complex. In the model, the anticodon loops of the P-site and A-site tRNAs contact one another in a way that is consistent with our combined tRNA efficiency data. These results suggest that tRNA-tRNA interactions that modulate tRNA action are an inevitable feature of translation.

Anticodon↗

Attitudes of psychiatrists toward diagnostic options and issues.

Debate regarding the control of mental health services has marked the mental health scene for several decades. The debate continued and broadened, however, with the publication of DSM-III. The ubiquitous use of that diagnostic system for third-party reimbursement led some mental health professionals to call attention to the likely possibility that whoever controls diagnosis will also control mental health (O'Keefe 1980). This study sought to gather attitudinal information on psychiatrists' views regarding DSM-III, alternative nosological models, selected adjunct issues related to the medical model and mental illness concepts, and other professional concerns.

Adult↗

Psychosocioeconomic predictors of treatment success/failure in chronic low-back pain patients.

The present study evaluated various psychosocioeconomic variables in chronic low-back pain (CLBP) patients being treated in a functional restoration rehabilitation program. The purpose of the study was to identify those factors that may have predictive value with respect to treatment outcome. Three groups of patients (Success, Failure, Dropout) were examined based on outcome and follow-up data 1 and 2 years after program completion. Once group assignment was made based on outcome, a variety of psychologic, socioeconomic, and demographic data obtained at the time of program admission was analyzed to determine if there were differences among the groups. Several factors were found to distinguish among the groups, including Minnesota Multiphasic Personality Inventory (MMPI) and Millon Behavioral Health Inventory (MBHI) scale scores, prior surgical history, level of worker compensation, and pain intensity ratings. These results confirm the presence of psychosocioeconomic differences among CLBP patients and suggest the need for continued research in this area to improve treatment efficacy in these patients.

Adult↗

Black and white adolescents' perceptions of their weight.

Black and white adolescents' perceptions of their weight were examined in this study. A 22-item questionnaire on weight perceptions and weight control was administered to 341 adolescents from two inner city schools in the midwest (138 black and 193 white students). Students were classified as thin, normal, or heavy based on National Health Survey data on height and weight measurements for youth ages 12-17. Significant differences (p less than .05) occurred in how the heavy black and white males and females perceived their weight in comparison to actual weight. All heavy white females perceived they were heavy, in comparison to only 40% of heavy black females; 78% of heavy white males labeled themselves heavy vs. 36% of heavy black males. Thin black and white females were dieting and exercising to lose weight and thin white males were exercising to lose weight. Black males were significantly more likely to believe emotions did not affect their weight when compared to white males. Black females believed exercise levels accounted for their weight, while white females attributed their weight to eating habits. Beliefs about exercise and eating contributed 23% to the variance found in perceived weight status of black males. White males believed access to food and their emotions accounted for their perceived weight. Leading sources of weight control information regardless of ethnicity were television, family members, friends and magazines for females; males used TV, family members, and athletic coaches.

Adolescent↗

Federal programs affecting rural perinatal health care.

Access to perinatal health care in rural communities often depends on such factors as the availability, cost, and acceptability of services. The federal government has been providing rural perinatal health care both directly and indirectly, through grants for service delivery or research and through direct payment for service. The various federal programs supporting perinatal health care in rural communities are described, and what may need to be done in the future is discussed.

Female↗

Capillary and size interrelationships in developing rat diaphragm, EDL, and soleus muscle fiber types.

The effects of maturation on the interrelationship between skeletal muscle fiber area and capillarization was investigated in specific fiber types (I, IIa, IIb, IIc) of male Wistar rats at seven developmental periods ranging from 8 to 85 days postnatal. Fiber type specific developmental properties were compared in three different muscles, the diaphragm (DIA), extensor digitorum longus (EDL), and soleus (SOL), which are known to differ widely in function. All fiber types in each of the three muscles examined exhibited large increases in area (FA), the magnitude and time course of the increase being related to both the type of fiber and the muscle in which the fiber was located. For type I fibers, areas increased from 3- to 18-fold (SOL greater than EDL greater than DIA), whereas in type IIa fibers, area increased ranged between 5- to 11-fold (SOL greater than EDL greater than DIA). Growth rates in IIb fibers were more homogeneous between muscles ranging from 11- to 14-fold. Capillarization, as indicated by the capillary contacts per fiber (CC), increased in all fiber types regardless of muscle origin. These increases ranged between 1.7- and 2.2-fold for type I fibers, between 2.4- and 2.5-fold for type IIa fibers, and between 2.0- and 3.0-fold for type IIb fibers. In general, capillary density expressed as the ratio of the number of capillary contacts divided by the fiber area (CC/FA) progressively declined in all fiber types with age. The rate of the decline in CC/FA was mediated in large part by the changes in fiber area.(ABSTRACT TRUNCATED AT 250 WORDS)

Aging↗

Periovulatory follicular fluid hormone levels in spontaneous human cycles.

We measured follicular fluid hormone levels in 48 normally cycling infertile women who underwent follicle puncture and oocyte retrieval during diagnostic laparoscopy at time-bracketed intervals after an endogenous LH surge. Follicular fluid LH, FSH, PRL, estrone (E1), estradiol (E2), progesterone (P), androstenedione (A), and testosterone (T) concentrations and P/E2 and A/E2 ratios were determined. Oocytes were classified as germinal vesicle (gv), metaphase I (mI), metaphase II (mII), or degenerating (dg). Follicular fluid (ff) hormone levels then were correlated with the stage of oocyte maturation. There were no differences in ff E1 or E2 levels at any stage of oocyte maturation, except that the mean ff E2 concentration was significantly (P less than 0.05) lower in ff containing dg oocytes [2,474 +/- 1,435 (+/- SE) nmol/L] than in those containing the other oocyte stages. The mean P levels were significantly (P less than 0.0001) higher in ff containing mI (48,781 +/- 10,240 nmol/L) and mII (41,801 +/- 11,098 nmol/L) oocytes than in ff containing gv oocytes (1371 +/- 696 nmol/L). The mean A level was highest (P less than 0.01) in dg-associated ff. Similarly, T was highest (P less than 0.05) in ff containing dg (52 +/- 14 nmol/L) oocytes than in ff containing mI (10.7 +/- 10.1 nmol/L) or mII (10.1 +/- 4 nmol/L) oocytes, and it was also elevated (P less than 0.05) in gv ff (72 +/- 33 nmol/L) compared to mII ff. The above differences also were reflected in the P/E2 ratio, which was significantly higher (P less than 0.05) in mI and mII ff, as well as in the A/E2 ratio, which was higher (P less than 0.05) in ff containing mI and mII oocytes compared to ff containing gv or dg oocytes. These data define the evolving changes in the microenvironment of the follicular fluid of preovulatory follicles of normally cycling women. They also provide reference points for analysis of ff obtained from women during stimulated cycles intended for in vitro fertilization.

Adult↗

The effect of prophylactic anti-asthma drugs on PAF-induced airway hyperreactivity.

Intravenous injection of platelet activating factor (PAF) in anesthetized guinea pigs induces non-selective airway hyperreactivity. This response to PAF was reduced in a dose-dependent manner by systemic administration of established prophylactic anti-asthma drugs (ketotifen, cromoglycate, aminophylline and glucocorticosteroids) and by competitive antagonists of PAF. These inhibitory effects could not be accounted for by antagonism of histamine (H1), serotonin or peptidoleukotrienes receptors; parasympatholytic activity; cyclo-oxygenase or lipoxygenase inhibition; mast cell stabilization; or bronchodilatation. Infusion or injection of PAF to induce airway hyperreactivity in the guinea pig may provide a prospective test for prophylactic anti-asthma drugs.

Animals↗