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Biomedical subjects

S W Sharkey

Publications and source records attributed to S W Sharkey.

53 records · Page 3Linked to original sources
PubMed1986

Two-dimensional echocardiographic detection of left ventricular posterior wall motion abnormalities using an inferior angulation view.

Two-dimensional echocardiography is frequently used to detect left ventricular (LV) wall motion abnormalities. Modification of the apical 4-chamber view by inferior angulation of the transducer provides a superior image for detection of regional wall motion abnormalities of the LV posterior wall. The inferior angulation image was prospectively compared with the standard parasternal short-axis image for detection of posterior LV wall motion abnormalities as defined by contrast left ventriculography in 63 consecutive patients. Posterior wall akinesia was present on the contrast left ventriculogram in 22 of the 63 patients. The parasternal short-axis image was judged technically inadequate for interpretation in 7 patients (11%). The inferior angulation image was technically adequate for interpretation in all patients. The sensitivity, specificity and accuracy of the inferior angulation image for detection of LV posterior wall motion abnormality was 91%, 80% and 84%, respectively, vs 67%, 71% and 70% for the parasternal short-axis image. The differences between the sensitivity, specificity and accuracy for the 2 views were not statistically significant. These observations indicate that the inferior angulation image provides a useful plane for routine echocardiographic analysis of regional LV wall motion either as a primary method to detect posterior wall motion abnormality or as a confirmatory view to document posterior wall motion abnormality.

Adolescent↗
PubMed1985

M-mode and two-dimensional echocardiographic analysis of the septum in experimental right ventricular infarction: correlation with hemodynamic alterations.

We investigated the changes that occur in the shape and the motion of the ventricular septum in experimental right ventricular (RV) infarction with M-mode and two-dimensional echocardiography. The echocardiographic findings were correlated with the hemodynamic alterations. Right ventricular infarction was produced by mercury embolization of the right coronary artery in five anesthetized closed-chest dogs. After embolization, the transseptal end-diastolic left-right ventricular pressure gradient reversed (3 +/- 1) to -1 +/- 1 mm Hg, p less than 0.001). The septal shape was altered by the flattening of the septum at end-diastole and a return to the normal septal shape during systole. Systolic septal motion was reversed after embolization (1 mm toward the left ventricle before embolization to 3 mm toward the RV after embolization, p less than 0.01). Septal thickening was not altered. We concluded that isolated RV free wall infarction results in the reversal of the transseptal end-diastolic pressure gradient and is associated with the flattening of the septum at end-diastole. During systole, the septum returns to its normal shape and moves toward the RV. In addition, systolic septal thickening is preserved. The motion of the septum toward the RV, together with normal septal thickening, may provide mechanical assistance to RV ejection with RV free wall infarction.

Animals↗
PubMed1984

Hemodynamic and clinical response to enalapril, a long-acting converting-enzyme inhibitor, in patients with congestive heart failure.

Enalapril, a new oral angiotensin converting-enzyme inhibitor, was administered to nine patients with severe congestive heart failure. Short-term hemodynamic response was noted within 2 hr and persisted for up to 24 hr. At peak effect mean arterial pressure fell from 83.4 +/- 10(SD) to 72.1 +/- 16.2 mm Hg (p less than .01), right atrial pressure from 13.6 +/- 6.0 to 10.4 +/- 7.5 mm Hg (p less than .01), pulmonary arterial pressure from 38.9 +/- 4.8 to 31.9 +/- 4.8 mm Hg (p less than .01), pulmonary capillary wedge pressure from 28.2 +/- 3.5 to 22.1 +/- 5.1 mm Hg (p less than .01), and total pulmonary resistance from 875 +/- 304 to 697 +/- 291 dynes-sec-cm-5 (p less than .05). Cardiac index was not changed, but there was a significant redistribution of regional blood flow with an increase of renal blood flow after enalapril. Plasma renin activity rose significantly from 6.2 to 28.6 ng/ml/hr, whereas plasma norepinephrine did not change after enalapril. Seven patients were treated with enalapril for 4 weeks. Five patients reported symptomatic improvement. Five of six patients tested had an increase in both exercise time (NS) and maximum oxygen consumption (NS). Repeat hemodynamic evaluation in six patients after long-term enalapril therapy showed a persistent effect with significant reductions in right atrial pressure from 13.8 +/- 7.2 to 7.1 +/- 4.7 mm Hg and in mean arterial pressure from 82.5 +/- 10.4 to 76.6 +/- 5.3 mm Hg and a significant increase in cardiac index from 2.1 +/- 0.5 to 2.5 +/- 0.5 l/min/m2 (all p less than .05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMedDate not supplied

Investigation of human enamel wear against four dental ceramics and gold.

OBJECTIVES: This in vitro study compared the wear of enamel against aluminous porcelin, bonded porcelain, low fusing hydrothermal ceramic, feldspathic machinable ceramic, and cast gold. METHODS: Fifty pairs of tooth-material specimens were tested in a dental wear machine, under a standard load (40 N), rate (80 cycles min-1) and for 25,000 cycles in distilled water. The amount of wear was determined by measuring the height loss of the tooth, and the depth of wear track of the restorative materials. RESULTS: There was a significant difference in wear among the groups for both enamel and materials (p < 0.001). Follow-up comparisons (95% CI significance level) showed that gold caused significantly less enamel wear than all ceramics tested. The amount of enamel wear in the aluminous and bonded porcelain groups was significantly higher than with the hydrothermal and machinable ceramic groups. There was no significant difference between the amount of enamel wear produced by the aluminous and bonded porcelains nor between that produced by the hydrothermal and machinable ceramics. Furthermore, the wear of the aluminous and bonded porcelains was significantly greater than that of the hydrothermal ceramic, the machinable ceramics and gold. No significant difference in wear was found between aluminous and bonded porcelains, hydrothermal and machinable ceramics, or between machinable ceramic and gold. However, the hydrothermal ceramic had significantly greater wear than gold. CONCLUSIONS: It was concluded that the hydrothermal and the machinable ceramics were significantly less abrasive and more resistant to wear than the conventional aluminous and bonded porcelains. Gold was the least abrasive material and most resistant to wear, although the difference in wear between the machinable ceramic and gold was not statistically significant.

Aluminum Oxide↗
PubMedDate not supplied

An evaluation of the T-Scan computerised occlusal analysis system.

A computerised system has recently become available to assist in occlusal analysis. An evaluation of this system is described, with particular emphasis on the measurement of bite force. A hand-held testing device and a Nene universal testing machine were used to apply force. A limited clinical trial was carried out on two volunteers with known occlusal interferences present. It was concluded that the system does not measure bite force accurately, but is useful as a clinical tool if used with care.

Bite Force↗
PubMedDate not supplied

Effect of water temperature on the accuracy of stone casts recovered from addition-reaction elastomeric impression materials.

This study investigated the accuracy of casts produced by mixing dental stone with water at different temperatures. Consecutive impressions of an acrylic resin model of the mandibular arch, on which the occlusal surfaces of three teeth had been indented with reference points, were made in two poly(vinyl siloxane) impression materials using a one-stage technique. After 1 hour these were cast in one of two stones using water at temperatures of 18 degrees C, 20 degrees C, or 24 degrees C. Five impressions were cast for each material at each temperature. The distances between the points were measured using a reflex microscope, and the difference between each cast and the model was calculated. Analysis of variance of the mean differences showed that there was no significant interaction between the temperature of the water and the accuracy of casts (P greater than 0.05).

Calcium Sulfate↗
PubMedDate not supplied

An in-vitro investigation of microleakage and gap size of glass ionomer/composite resin "sandwich" restorations in primary teeth.

Eighty extracted primary molars were divided into four groups of twenty teeth. Class II cavities were prepared in all teeth with equal numbers of proximal boxes having cavosurface margins either in enamel, or dentin/cementum. Each group was allocated to an open or closed sandwich technique using glass ionomer as a lining. Following the placement of the composite resin restorations, the gap size measured at the proximal box was greatest for the closed sandwich group with the cavosurface margin on enamel (0.203 microns) or dentin/cementum (0.174 microns). Microleakage scores were measured at the proximal box and were greatest for the closed sandwich group with the cavosurface margin on dentin/cementum. The best result was obtained for the open sandwich group with the cavosurface margin on enamel.

Analysis of Variance↗
PubMedDate not supplied

The abrasive effect of glazed, unglazed, and polished porcelain on the wear of human enamel, and the influence of carbonated soft drinks on the rate of wear.

The abrasive effect of various porcelain surfaces on human enamel was studied in vitro. Sixty pairs of tooth-porcelain specimens were tested under a standard load and rate in distilled water and with and without intermittent exposure to a carbonated beverage. The amount of wear of enamel and porcelain specimens was determined after 5,000, 15,000, and 25,000 cycles. After 25,000 cycles there was no significant difference in the enamel wear between glazed and polished groups, but wear produced by the unglazed groups was significantly higher (P < .05). Overall, exposure to a carbonated beverage significantly increased the amount of enamel wear produced by all porcelain surfaces (P < .001). The finish of the porcelain surface did not influence its wear.

Aluminum Oxide↗