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Biomedical subjects

M D Smith

Publications and source records attributed to M D Smith.

At least 379 records · Page 21Linked to original sources
PubMed1991

Evaluation of valvular regurgitation by Doppler echocardiography.

Although most clinical decisions about timing of intervention remain based on symptoms or evidence of progressive ventricular dysfunction in valvular regurgitation, several available Doppler techniques can give confirmation of the presence of significant insufficiency. For these reasons, the 2D echocardiographic and Doppler evaluation has become an integral part of the diagnostic and clinical management of these patients. These imaging techniques are still in their infancy, however, and the exact relationship between jet appearance and clinical and hemodynamic implications remains to be defined. Newer approaches to color flow display of Doppler velocity information, such as power mode, quantification of jet momentum, and kinetic energy mapping may provide a better understanding of the dynamic nature of valvular regurgitation. In the future, Doppler recordings may provide the basis for a more sophisticated understanding of the hydrodynamics of valve dysfunction.

Echocardiography, Doppler↗
PubMed1990

Effect of isometric exercise on mitral and aortic regurgitation as assessed by color Doppler flow imaging.

Isometric exercise produces well-defined hemodynamic changes in normal and diseased states. However, the effect of isometrics on the degree of valvular regurgitation recorded by color Doppler flow imaging (CDFI) has not been reported. CDFI was therefore used to evaluate changes in valvular regurgitation in 34 patients, mean age 53 +/- 16 years. Data were collected for 43 regurgitant lesions including 20 cases of aortic regurgitation and 23 cases of mitral regurgitation. Isometrics produced a significant increase in heart rate (71 to 83 beats/min) and blood pressure (132/64 to 153/70 mm Hg) in all patients (p less than 0.0001). Regurgitant jet area by CDFI increased significantly in both aortic regurgitation (4.5 to 6.2 cm2, p less than 0.0001) and mitral regurgitation (6.2 to 8.2 cm2, p less than 0.001). Patients taking concurrent vasodilator or angiotensin-converting enzyme inhibitor therapy had similar responses to those not receiving long-term therapy. Thus, CDFI detects an increase in aortic and mitral regurgitant jet area induced by isometric exertion. The change in CDFI jet area with handgrip demonstrates the influence of loading conditions on the size of a regurgitant jet area, and suggests that isometric exertion may increase the magnitude of mitral and aortic regurgitation.

Aortic Valve Insufficiency↗
PubMed1990

Polymorphism and expression of the galactosyltransferase-associated protein kinase gene in normal individuals and galactosylation-defective rheumatoid arthritis patients.

We used restriction endonuclease digestion of leukocyte DNA to assess the structural integrity of an N-acetylglucosamine beta 1----4 galactosyltransferase (GalTase)-associated (GTA) protein kinase gene in rheumatoid arthritis (RA) patients. This analysis provides evidence that the gross structure of the GTA protein kinase gene locus remains intact in patients with defective galactosylation and that this gene locus is polymorphic both in normal individuals and in patients with RA, although no polymorphisms unique to RA patients were observed. Initial data on the expression of this gene indicate that comparable levels of GTA protein kinase messenger RNA are present in the lymphocytes of normal individuals and RA patients, irrespective of whether lymphocytes were obtained from patients with decreased or normal levels of galactosylation.

Acetylglucosamine↗
PubMed1990

Gas chromatography/negative ion chemical ionization/tandem mass spectrometric quantification of indomethacin in plasma and synovial fluid.

A procedure for the quantification of sub-nanogram per millilitre concentrations of indomethacin in plasma and synovial fluid has been developed using gas chromatography/negative ion chemical ionization/tandem mass spectrometry. The procedure is based on selected ion monitoring of the daughter ion at m/z 312 generated following decarboxylation of the 35Cl isotope peak of the indomethacin anion (m/z 356) formed from the pentafluorobenzyl ester of indomethacin in the ion source of the mass spectrometer. The internal standard, d2-indomethacin, has a daughter ion at m/z 316 formed from the corresponding 37Cl isotope peak. The limit of quantification was 0.1 ng ml-1 for both plasma and synovial fluid.

Chlorine↗
PubMed1990

Removal of retained intracoronary percutaneous transluminal coronary angioplasty equipment by a percutaneous twin guidewire method.

Balloon rupture during percutaneous transluminal coronary angioplasty (PTCA) resulted in embolization of a guidewire-balloon fragment into the distal circumflex artery. Access to the circumflex was technically difficult because of aortic root dilation. The fragment was removed by inserting two PTCA guidewires into the artery and twisting them together to produce a helix. The helix propagated distally, entrapping the embolized fragment for removal. This report describes an unusual mode of failure for a balloon-on-a-wire dilating catheter and a new percutaneous removal technique that may be applied to retained catheter debris in small, inaccessible vessels.

Angioplasty, Balloon, Coronary↗
PubMed1990

Methanol is a potent inhibitor of the metabolism of endogenous arachidonic acid by elicited rat peritoneal leukocytes.

The effect of methanol on the ability of elicited rat peritoneal leukocytes to metabolise endogenous and exogenous arachidonic acid was studied using 2H8-arachidonic acid as the source of exogenous arachidonic acid and calcium ionophore A23187 as the lipoxygenase stimulus. As the methanol concentration increased from 0 to 992 mM there was a slight decrease in the total amount of LTB4 and related compounds formed, however examination of the ratio of undeuterated to deuterated LTB4 formed revealed that as the methanol concentration increased from 0 to 992 mM, the percentage of undeuterated LTB4 present decreased significantly from 57 +/- 9% to 2 +/- 1%. Methanol interferes with the ability of these cells to utilise endogenous arachidonic acid even in the presence of the powerful stimulus calcium ionophore A23187 thus allowing the facile biosynthesis of a range of deuterium labelled arachidonic acid metabolites.

Animals↗
PubMed1990

Relation of echocardiographic morphology of the mitral apparatus to mitral regurgitation in mitral valve prolapse: assessment by Doppler color flow imaging.

Few data exist regarding the relationship of valvular anatomy and coaptation to the presence of mitral regurgitation (MR) in patients with mitral valve prolapse (MVP). Therefore this study was undertaken to assess the ability of two-dimensional echocardiographic features of mitral valve morphology to predict the presence, direction, and magnitude of MR as assessed by color Doppler flow imaging. MR was present in 21 of 46 patients with MVP on two-dimensional echocardiography. Echocardiograms were specifically evaluated for leaflet apposition, leaflet morphology, and mitral anulus diameter. Color flow images were analyzed for presence of MR, direction of the regurgitant jet, and area encompassing the largest jet visible in any view. Abnormal mitral leaflet coaptation on two-dimensional echocardiography was strongly associated with the presence of MR (p = 0.003), being present in 15 of 21 patients with as compared with 5 of 25 patients without MR. Similarly, mitral leaflet thickness and MR were closely associated (p = 0.0035), with the latter being present in 9 of 30 patients with normal and 12 of 16 patients with excessive leaflet thickness. MR jet direction tended to be anterior to central with posterior leaflet prolapse and posterior or central with anterior leaflet prolapse (p = 0.02). Maximal jet area of MR tended to be larger in patients with compared with those without mitral annular dilatation (5.4 +/- 2.3 versus 2.1 +/- 1.9 cm2, p = 0.001), and in those with abnormal rather than normal leaflet thickness (4.5 +/- 2.7 versus 2.0 +/- 1.6 cm2, p = 0.009). Thus the presence, direction, and size of MR jets in MVP are related to structural abnormality of the mitral apparatus on echocardiography.

Adolescent↗
PubMed1990

T gamma delta-cell subsets in cord and adult blood.

A minor population of T cells expresses a heterodimeric antigen receptor composed of gamma and delta chains (TcR-1). In blood from adults, two subsets of T gamma delta cells can be identified by the monoclonal antibodies (MoAb) BB3 and A13. Little is known about the distribution and markers of these subsets early in life. We have therefore examined both the frequencies of these cells in cord blood and their expression of the cytotoxicity-associated marker serine esterase (SE), using immunocytochemical techniques. Our data show lower percentages of TcR-1+ cells in the blood of newborns compared with that in adults. However, the ratio of the A13+/BB3+ cells was significantly higher in cord than in adult blood. Whereas virtually all the adult TcR-1+ cells in blood were SE-positive, only a small proportion of the cord blood cells carried this enzyme. This was restricted to the BB3+ T gamma delta-cell subset in the cord. Our data suggest different characteristics of the TcR-1+ cells in blood from newborns compared with adult blood, and study of the functions of the different subsets, e.g. cytotoxicity, will be important in understanding their particular role in immunity.

Adult↗
PubMed1990

T gamma delta cells and their subsets in blood and synovial tissue from rheumatoid arthritis patients.

We have examined the frequencies of T gamma delta cells in blood, synovial fluids, and synovial membranes of patients with rheumatoid arthritis (RA) and in blood from age-matched controls. Immunocytochemical and immunohistochemical techniques were used with monoclonal antibodies BB3 and A13 to define a major and minor blood subset of T gamma delta cells respectively. Together, these antibodies identify the majority (if not all) of the peripheral blood T gamma delta cells. Significantly lower levels of T gamma delta cells were found in the blood of RA patients compared with controls, whilst higher but not significant numbers were found in the synovial fluids of paired samples. Scattered T gamma delta cells were found only in some synovial membranes with a distribution similar to the T alpha beta cells. Analysis of the two different T gamma delta-cell subsets indicated a ratio of BB3 to A13 of about 5:1 in control and RA blood. However, this ratio was less than 1:1 in the RA synovial fluids and membranes. The migratory nature of the A13+ cells could account for their predominance in these sites. The possible pathological significance of these cells in the rheumatoid synovial fluid and synovial membranes is discussed.

Adult↗
PubMed1990

Lymphocyte surface marker expression in rheumatic diseases: evidence for prior activation of lymphocytes in vivo.

Expression of major histocompatibility complex (MHC) class II and other lymphocyte activation markers on peripheral blood and synovial fluid T lymphocytes from patients with rheumatoid arthritis (RA), psoriatic arthritis, and Reiter's syndrome were measured and the mean fluorescence intensities of these antigens were assessed. Increased expression of MHC class II antigens of synovial fluid T lymphocytes is not unique to RA, though it is quantitatively greater on RA synovial fluid T cells. There was less expression of other lymphocyte activation markers (4F2, transferin receptor) and a marked discordance between the expression of these markers and the interleukin 2 receptor (IL2r). Synovial fluid T lymphocytes contain a subpopulation of larger cells expressing MHC class II and other lymphocyte activation antigens with the exception of the IL2r. Mean fluorescence intensity of CD3 and CD4 antigens on synovial fluid T lymphocytes was decreased in all three patient groups, suggesting prior in vivo exposure of synovial fluid T lymphocytes to an unknown antigen.

Aged↗
PubMed1990

Does steroid pulsing influence the efficacy and toxicity of chrysotherapy? A double blind, placebo controlled study.

To test the hypothesis that early steroid pulsing augments the efficacy and decreases the toxicity of chrysotherapy 40 patients with rheumatoid arthritis were studied in a double blind, placebo controlled study. During the first three months of gold treatment group 1 received monthly intravenous methylprednisolone pulsing (steroid group) while group 2 received placebo (placebo group). All patients were assessed clinically and serologically over a 24 week period. Twelve patients were withdrawn before completion of the study and all but one of the remaining 28 patients reported clinical and serological improvements. Two patients in the steroid group were withdrawn owing to gold induced side effects while four were withdrawn in the placebo group. These small numbers were not significantly different. Minor side effects occurred more commonly in the placebo group. The clinical response was clearly better in the steroid group with statistical significance almost being achieved. In an endeavour to obtain a significant conclusion further patients will now be entered into this study.

Aged↗
PubMed1990

Patriarchal ideology and wife beating: a test of a feminist hypothesis.

Feminist theory suggests that husbands who adhere to an ideology of familial patriarchy are more likely to beat their wives than husbands who do not adhere to such an ideology. This research provides quantitative data from a representative sample survey of women in the general population that support the feminist thesis. The results also indicate that husbands with relatively low incomes, low educational attainment, and low-status jobs were significantly more likely than higher status husbands to espouse such an ideology.

Adolescent↗