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Biomedical subjects

D Smith

Publications and source records attributed to D Smith.

At least 1,027 records · Page 57Linked to original sources
PubMed1984

Platelet adherence to bioprosthetic cardiac valves.

Tissue from porcine aortic bioprosthetic valves (Hancock) and bovine pericardial valves (Ionescu-Shiley) were incubated with platelets tagged with chromium-51. There was a significantly decreased platelet-collagen adhesion reaction in both porcine and bovine glutaraldehyde-treated valves compared with reactions in fresh porcine aortic valve and fresh bovine pericardium (p less than 0.001). There was no significant difference in the platelet-collagen reaction between porcine aortic valve and bovine pericardium, whether treated with glutaraldehyde or in the fresh state (p greater than 0.05). The addition of aspirin did not significantly decrease the platelet-collagen reaction on glutaraldehyde-treated or fresh valves (p greater than 0.05). Rinsing fresh valves in plasma appeared to offer more protection against platelet adhesion than rinsing them in saline solution (p less than 0.01). It is concluded that there is no difference in platelet adherence to porcine aortic valve or bovine pericardium and that glutaraldehyde, and perhaps plasma, offers a protective effect against platelet adhesion.

Animals↗
PubMed1984

Binding of sulfadimethoxine to isolated human blood protein fractions.

The binding of sulfadimethoxine to selected human blood protein fractions and to fresh serum has been examined by means of a new equilibrium dialysis technique which minimizes experimental error and permits the evaluation of low-level binding. Certain alpha-globulin fractions, containing mixtures of proteins, were found to bind the drug. Scatchard analysis of the binding of sulfadimethoxine to fresh serum, calculated as though all of the binding is due to albumin, gives a different result from that obtained with isolated albumin. This may be a reflection of the contribution of the alpha-globulins to the overall binding of sulfadimethoxine in fresh serum. Although sulfadimethoxine is amphoteric, it did not bind to the alpha 1-acid glycoprotein. The drug behaves as an acidic compound when binding to the blood proteins.

Alpha-Globulins↗
PubMed1984

An improved traction system for fragile bones.

The problems of transcutaneous tibial pins for skeletal traction in elderly patients are considered, and the reasons behind loosening of the pin are discussed. A novel method of skeletal traction using two pins is proposed.

Aged↗
PubMed1984

A radioassay for angiotensin converting enzyme.

Current methods for measuring angiotensin converting enzyme activity (EC 3.4.15.1, ACE) are somewhat cumbersome and have limited the general availability of the test. We describe here a simple four-step radioassay for ACE which uses the substrate 14C-Hippurate-L-Histidyl-L-Leucine and measures the product, 14C-Hippurate. We found that incubation at pH 7.0 (Hepes buffer) increased the sensitivity of the test by 50 percent when compared to results obtained with the pH 8.0 buffer normally used for ACE assays. A split sample comparison study between the radioassay and the spectrophotometric method showed good correlation (n = 47; mean, spectrophotometric, 26.0 U/mL; mean, radioassay, 26.1 U/mL; m = 0.86; b = 3.9; r = 0.868). We found that there was no significant difference between the spectrophotometric, kinetic and radioassay (Newman-Keuls multiple range test), but the liquid chromatographic method gave results significantly different from the other methods. The assay for ACE described here combines enhanced technical ease with the sensitivity of a radioassay.

Carbon Radioisotopes↗
PubMed1984

Mechanical vibration transmission characteristics of the left ventricle: implications with regard to auscultation and phonocardiography.

Systolic-diastolic phasic alteration of left ventricular mechanical vibration transmissibility was studied in an open chest canine preparation. A continuous vibratory tone was applied to the base of the heart, and a miniature heart surface vibration sensor applied to the epicardium near the ventricular apex. This allowed the detection of the percent of the vibration that was transmitted from source to sensor. These data were compared with those from intracardiac phonocardiograms obtained using a micromanometer-tipped catheter. It was found that in systole, the ventricle transmitted a vibratory tone from the cardiac base to the apex so that it was readily detected by the heart surface sensor. In marked contrast, during diastole the relaxed ventricle failed almost completely to transmit the vibration to the apical position. When the dog experienced heart failure during hypoxia, the ventricular diastolic vibration transmissibility was found to equal or exceed that of the systolic phase.

Animals↗
PubMed1984

Infectious mononucleosis: a polyclonal B cell transformation in vivo.

We obtained spontaneous formation of Epstein-Barr virus-transformed B lymphocyte colonies from the blood of four patients with mononucleosis with the use of soft-agar medium. The colonies were propagated into separate cell lines and analyzed for their immunoglobulin secretion. Of 52 such lines, 44 produced immunoglobulin composed of a single class of heavy chain and single type of light chain. Among these clonal transformants, 27 (62%) of 44 produced mu-chain, 13 (29%) of 44 produced gamma-chain, and 4 (9%) of 44 produced alpha-chain. Analysis of light-chain secretion revealed that of the 44 cell clones secreting complete, monoclonal immunoglobulin products, 31 produced kappa-chain and 13 produced gamma-chain. One clone secreted mu-heavy chain and no light chain, an observation suggesting the clone is a pre-B cell phenotype. Seven lines derived from clones had aberrant patterns of immunoglobulin secretion that produced either two heavy chains or two light chains. B lymphocytes in different states of immunoglobulin gene expression are, therefore, transformed in vivo by Epstein-Barr virus.

Antibodies, Viral↗
PubMed1984

Dermatomal somatosensory evoked potentials: their use in lumbar radiculopathy.

The accurate diagnosis of lumbar radiculopathy secondary to intervertebral disc herniation or spinal stenosis remains a significant problem. Studies have stressed that misdiagnosis of root entrapment significantly contributes to the incidence of failed back syndrome. In an attempt to aid the proper selection of surgical candidates, dermatomal somatosensory evoked potentials ( DSSEP ) have been used in conjunction with standard diagnostic techniques to evaluate our patients. The advantage of this technique lies in the root specificity. The authors studied the DSSEP using two methods. In Method 1, using myelograms as the standard, the accuracy was 85.7%. In Method II, using surgical outcome as the standard, the accuracy was 87.5%. As a result, the authors have found the noninvasive, relatively inexpensive DSSEP to be a useful adjunct in the selection of patients undergoing lumbar spine surgery.

Afferent Pathways↗
PubMed1984

Insulin-mediated potassium uptake is normal in uremic and healthy subjects.

We examined the ability of physiological hyperinsulinemia to enhance potassium and glucose uptake by splanchnic and peripheral tissues in 12 chronically uremic subjects by using the euglycemic insulin clamp technique in combination with hepatic and femoral venous catheterization. In control subjects, the decline in plasma potassium concentration averaged 0.95 +/- 0.05 meq/liter. Splanchnic (67 +/- 10.3 mu eq/min) and leg (22.2 +/- 1.4 mu eq/min) potassium uptake accounted for 43 and 59%, respectively, of the total amount of potassium that was translocated from the extracellular to intracellular fluid compartment. In uremic individuals, the decline in plasma potassium concentration (0.98 +/- 0.10) was similar to controls. Likewise, the mean splanchnic (66.6 +/- 6.1 mu eq/min) and leg (22.4 +/- 1.6 mu eq/min) potassium uptakes were similar to controls. These results indicate that insulin-mediated potassium uptake is not altered by uremia. In contrast, insulin-mediated glucose uptake is markedly impaired. These observations suggest that the various actions of insulin can be differentially impaired by uremia and that steps distal to the insulin receptor must be responsible for the insulin resistance.

Adult↗
PubMed1984

An investigation of role-taking in histrionic personalities.

Gough's theory that psychopathy stems from a deficiency in role taking, the ability to perceive and evaluate one's own behaviour as it is perceived and evaluated by others in the same culture, was tested. The Socialization scale, developed by Gough to assess role taking, was administered to a group of 20 female psychiatric patients with histrionic personality disorders, and a control group of female depressives of similar age and intelligence. Socialization scores of the histrionic personalities were significantly lower, indicating impaired role taking, and this difference was not attributable to depression of mood. The Socialization scale was a better discriminator between the groups than the scales of two other personality inventories or a test to elicit meta-impressions.

Adult↗
PubMed1984

Specific insulin binding sites in human ovary.

The strong association between hyperinsulinemic states of insulin resistance and ovarian hyperandrogenism has led to the suggestion that insulin might directly influence the function of the ovary. To assess this possibility, we have attempted to directly measure insulin receptors in the ovarian stroma of three patients who were operated upon for polycystic ovarian disease. 125I-insulin binding was easily detectable in fragments of ovarian stroma in each case. Specific binding was totally inhibited by pre-treatment with serum containing specific anti-insulin receptor autoantibodies (B-2). These data are consistent with the hypothesis that insulin can directly influence ovarian function. Further studies of insulin receptors and insulin action in human ovarian tissue could lead to a better understanding of the link between insulin resistant states and ovarian hyperfunction.

Adult↗
PubMed1984

Mechanism of improvement in glucose metabolism after chronic glyburide therapy.

The effect of glyburide on glucose metabolism was examined in 10 non-insulin-dependent diabetic subjects (NIDDM) and 7 young, control subjects. After 3 mo of glyburide treatment in NIDDM, fasting plasma glucose declined from 198 to 141 mg/dl (P less than 0.01) without change in fasting insulin levels. Basal hepatic glucose production (HGP) was slightly elevated in NIDDM versus controls (2.35 versus 2.18 mg/kg X min, P = NS) and was positively correlated with the fasting glucose concentration (r = 0.93, P less than 0.001). With chronic glyburide therapy, HGP declined to 1.72 mg/kg X min (P less than 0.01 versus preglyburide) and remained highly correlated with the fasting glucose concentration (r = 0.85, P less than 0.005). Basal glucose clearance in NIDDM was reduced by 48% compared with age-matched controls (1.22 versus 2.32 ml/kg X min, P less than 0.001) and was unchanged after 3 mo of glyburide. Thus, the most important factor responsible for the decline in fasting plasma glucose concentration was an inhibition of hepatic glucose output. The decrease in basal hepatic glucose production and fasting plasma glucose concentration occurred without any change in fasting plasma insulin or C-peptide concentration. Insulin-mediated glucose metabolism (insulin clamp technique) was reduced by 55% in NIDDM (2.91 versus 6.39 mg/kg X min, P less than 0.001). After glyburide, insulin-mediated glucose metabolism increased by 26% to 3.67 mg/kg X min (P less than 0.01). This increase in tissue sensitivity to insulin was unassociated with any change in insulin binding to monocytes.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗