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Biomedical subjects

B E Hayes

Publications and source records attributed to B E Hayes.

14 recordsLinked to original sources
PubMed2003

Gender difference in vascular and platelet reactivity to thromboxane A(2)-mimetic U46619 and to endothelial dependent vasodilation in Zucker fatty (hypertensive, hyperinsulinemic) diabetic rats.

We examined the hypothesis that gender differences exist in platelet and vascular reactivity in type-2 diabetes mellitus, using Zucker fatty diabetic rats of both sexes and their lean littermates. Type-2 diabetes is characterized by excessive platelet production of TXA(2), which is thrombogenic. Testosterone up-regulates platelet TXA(2) receptors and the aggregation response to thromboxane mimetics. Conversely, estrogen increases vascular nitric oxide (NO) production and inhibits platelet aggregation. Hemodynamic studies were undertaken with the determination of dose-response curve for MAP and renal cortical blood flow (RCF) in response to U46619, angiotensin-II, phenylephrine and endothelin-1, as well as the systemic hemodynamic response to acetylcholine and L-NG nitro-arginine methylester (L-NAME). Platelet aggregation response was evaluated using whole blood impedance aggregometry. There were significant gender differences in the systemic blood pressure and RCF response to TXA(2)-mimetic U46619 and angiotensin-II (P<0.02, ANOVA) but not to phenylephrine or endothelin-1. Male rats exhibited a paradoxical hypotensive response to U46619 (-18+/-11 mmHg) compared with a peak pressor response of +6+/-1 mmHg in female rats (P<0.01, ANOVA). The male rats exhibited an attenuated systemic vasodilator response (P<0.001, ANOVA) to acetylcholine (fall in MAP in male diabetic rats being -24+/-8 mmHg, compared with a fall of -50+/-8 mmHg in females), but a greater rise in the renal cortical resistance in response to NO inhibition by L-NAME (P<0.03) compared with the female rats. Both the slope (46+/-2) and the peak magnitude of the U46619-induced whole blood platelet aggregation (13+/-1) ohms were significantly higher (P<0.01, ANOVA) in male (n=10) compared with female diabetic rats (n=8) (29+/-0.8 slope, 10.0+/-0.8 ohms, respectively). Thus, the male diabetic Zucker rats exhibited an impaired response to vasoconstrictors (U46619 and angiotensin-II) and to endothelial (NO)-mediated vasodilation. The male gender may therefore be associated with the greater prothrombotic activity and a worse impairment of endothelial reactivity in the type-2 diabetic state.

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗
PubMed2000

Butyrate inhibits proliferation-induced proliferating cell nuclear antigen expression (PCNA) in rat vascular smooth muscle cells.

Arterial injury-induced vascular smooth muscle cell (VSMC) proliferation in intima is the important etiologic factor in vascular proliferative disorders such as atherosclerosis, hypertension and restenosis after balloon angioplasty. Butyrate, a naturally occurring short chain fatty acid, is produced by bacterial fermentation of dietary fiber and by mammary glands of certain mammals. Studies have shown that butyrate at millimolar concentrations, which are physiological, induces growth arrest, differentiation and apoptosis. We examined the effect of physiological concentrations of butyrate on rat VSMC proliferation and proliferation-induced PCNA expression to determine anti-atherogenic potential of butyrate. Butyrate concentrations, closer to physiological range, exhibited antiproliferative effects on both serum-induced proliferation of serum-starved quiescent VSMCs and actively proliferating non-confluent VSMCs. Treatment of serum-starved quiescent VSMCs with 1-8 mmol/l concentration of butyrate caused a concentration-dependent decrease in serum-induced VSMC proliferation and cell proliferation-associated increase in total cellular proteins and RNA levels. Similarly, exposure of actively growing VSMCs to 5 mmol/l butyrate resulted in the inhibition of cell proliferation and proliferation-induced increase in cellular proteins and RNA levels. Furthermore, cellular morphology was significantly altered. Analysis of cell cycle regulatory proteins indicated that levels of PCNA, an excellent marker for cell proliferation, was significantly altered by butyrate both in actively proliferating and serum-induced quiescent VSMCs. These observations suggest that butyrate exhibits potential antiatherogenic capability by inhibiting VSMC proliferation and proliferation-associated increase in PCNA expression and thus merits further investigations regarding therapeutic significance of butyrate in vascular proliferative disorders.

Animals↗
PubMed1994

Use of the theory of reasoned action to predict drug and alcohol use.

The present study examines the role of self-esteem (SE) in the prediction of drug and alcohol use. Consistent with research on the theory of reasoned action, we suggest that alcohol and drug attitudes and subjective norms are more useful in the prediction of self-reported drug and alcohol consumption than SE. In the present study, measures of SE, drug attitudes, subjective norms, and drug use behaviors were collected from 2,074 high school and college students. Results indicate that drug attitudes and subjective norms do predict drug and alcohol use, but that SE does not add significantly to the prediction of the drug and alcohol behaviors.

Adolescent↗
PubMed1993

Satisfaction with health-related educational workshops: the role of environmental and logistical factors.

The present study examined correlates of the perceived quality of four educational conferences. Specifically, the study examined the relationships of ratings of subjective overall conference quality with environmental and logistical aspects of the conferences. The results showed that ratings of room quality as well as ratings of meeting structure were significantly related to ratings of overall conference quality. Follow-up coverall conference ratings, measured up to one year after the conferences, were predicted by initial ratings of food quality.

Adolescent↗
PubMed1993

Measuring intramedullary nails.

Determining the length of nail needed for intramedullary nailing can sometimes be difficult. This article describes a simple procedure for taking this important measurement.

Bone Nails↗
PubMed1992

How to weigh a patient who is over 350 pounds.

Every so often a physician needs to weigh someone who exceeds the weight limit of the standard office scale. This short tip describes an easy and quick method of obtaining the weight of someone who is over 350 pounds.

Anthropometry↗
PubMed1990

Semicarbazide-sensitive amine oxidase activity in streptozotocin diabetic rats.

Semicarbazide-sensitive amine oxidase (SSAO) activity was investigated in serum and tissues of streptozotocin diabetic rats. Diabetes was induced by a single intraperitoneal injection of streptozotocin (STZ, 60 mg/kg) and rats were killed at 1, 3, 7, 9, 14, 28 and 56 days after treatment. STZ increased serum glucose and serum SSAO activity at all time points with a maximal increase (2 to 3 fold) at day 7. Kidney SSAO activity showed significant increases on days 9 and 14 (2.5 and 4 fold, respectively). SSAO activity of aorta, lung and pancreas was not changed significantly. Kinetic analysis showed that the elevation in both serum and kidney SSAO activity was due to an increased Vmax with no change in Km. SSAO activity appears to be selectively increased in the serum and kidney of STZ diabetic rats which may be indicative of a relationship between serum SSAO and early renovascular damage in this animal model of diabetes mellitus.

Amine Oxidase (Copper-Containing)↗
PubMed1985

Benzylamine oxidase activity in spontaneously hypertensive rats.

Benzylamine oxidase (BzAO) activity was assayed in aorta, atria and serum from 20 week old spontaneously hypertensive (SH) rats and Wistar Kyoto (WKY) control rats. Atrial BzAO activity was reduced by 50% in SH rats compared with WKY control. Aorta and serum BzAO activity did not differ significantly between the two groups. Thus, BzAO activity of serum and cardiovascular tissues appears unrelated to pressure-induced changes in connective tissue production.

Animals↗
PubMed1984

Limitations of thermodilution cardiac output measurements in the rat.

Heat loss from the vascular system could introduce an error in thermodilution cardiac output determinations. Cardiac output measured in the rat via the thermodilution technique following right atrial injection yielded different values (P less than 0.001), depending whether sampling was from the pulmonary artery (460 +/- 31 ml X min-1 X kg-1), right ventricle (311 +/- 19), or thoracic aorta (245 +/- 15). Recirculation errors could not account for the differences. Heat loss from the vascular system was measured from extravascular thermistors within both the thorax and the abdomen. These dilutions were 22-57% in peak height of aortic curves recorded at approximately the same location. Differences in calculated cardiac output between sampling sites could be attributed to rapid heat conduction directly from the right atrium and inferior vena cava to the thoracic aorta with progressive loss of indicator from both the right ventricle and pulmonary artery.

Animals↗
PubMed1983

Benzylamine oxidase in normal and atherosclerotic human aortae.

Assays of serum benzylamine oxidase (BzAO) have led some workers to postulate a relationship between elevated BzAO activity and diseases characterized by proliferating connective tissue. The present study was designed to determine whether BzAO activity of a cellular tissue is also affected. BzAO was assayed in homogenates of normal and atherosclerotic human aortae. Characterization done in normal aortae showed that BzAO is not a classical monoamine, diamine, polyamine, or lysyl oxidase, nor is it a ceruloplasmin. The enzyme is heat stable at 60 degrees C and is associated primarily with the microsomal fraction on density centrifugation. Compared with phenylethylamines and indoleamines, benzylamine is the best substrate. BzAO is sensitive to inhibition by hydrazines and chymotrypsin but not trypsin, and is insensitive to Triton X-100 and sulfhydryl-group blockade. BzAO activity of atherosclerotic plaque (expressed per gram wet weight or per milligram protein) was decreased markedly compared to that in adjacent, nonplaque regions and in normal aortae. However, on a per milligram DNA basis, the BzAO activity of plaque did not differ from that of nonplaque tissue. We conclude that there is a decreased cell population density in plaque, a contention supported by kinetic analysis. Plaque BzAO showed a decreased Vmax with no change in the Km of benzylamine compared with nonplaque tissue. Thus, if a relationship exists between BzAO activity and proliferating connective tissue, it is not apparent at the level of the cellular enzyme in atherosclerotic aortae of man.

Adolescent↗
PubMed1983

Effect of ovariectomy and estrogen treatment on uterine benzylamine oxidase and monoamine oxidase type A.

The activity of monoamine oxidase type A (MAO-A) of rat uteri is known to be modulated by sex steroids but no information is available with regard to benzylamine oxidase (BzAO). Thus, uterine MAO-A and BzAO activities were assayed in ovariectomized (3 weeks) and ovariectomized plus estrogen treated rats (17 beta-estradiol, 10 micrograms/kg/day, i.p. for three days). Compared with sham operated controls, MAO-A activity (total and specific) was decreased by ovariectomy and restored partially by estrogen treatment. In contrast, BzAO activity was not influenced selectively. Total BzAO activity followed changes in uterine weight such that the specific activity of BzAO, per mg tissue, was not statistically different between the three experimental groups. Although changes in the specific activity of BzAO were found on a protein and DNA basis, these changes reflect primarily alterations in protein and DNA contents and not BzAO activity. Since BzAO appears to be insensitive to direct modulation by sex steroids and may be located predominantly in uterine blood vessels, it is speculated that the enzyme may serve as a marker for hormonal influences on the vascularity and structure of the uterine vascular bed.

Animals↗
PubMed1978

Pulmonary artery catheterization in the rat.

A method of pulmonary artery (PA) catheterization in the closed-chest rat is described. This catheterization is best accomplished with teflon catheters having a "shepherd's crook" tip. Catheter preparation is detailed. The functional advantages of such a PA catheter are: 1) the tip can remain free within the right ventricle (RV) without becoming occluded by contact with the ventricular wall, and 2) entry into the PA is simple and reproducible. Dual catheterization of the RVand PA produced only a small systolic gradient (3 mmHg) across the pulmonic valve. We concluded that the PA catheter does not unduly obstruct blood flow through this valve.

Animals↗