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Biomedical subjects

M E McKinney

Publications and source records attributed to M E McKinney.

14 recordsLinked to original sources
PubMed1990

Cardiovascular reactivity to stress: an examination of familial trends.

Mental stress elicits changes in cardiovascular functioning such as increases in blood pressure and heart rate and leads to biochemical changes which may facilitate the development of cardiovascular disease. This study examined the correlations between levels of cardiovascular change seen in healthy fathers and their sons who underwent stress testing (cold pressor test and mental arithmetic). No correlation between fathers' and sons' levels of reactivity were found. Certain personality traits such as hostility and anger directed inward have previously been shown to correlate with both reactivity and presence of arterial disease. In this study, hostility levels and assertiveness levels were measured and were found to correlate modestly with reactivity in the fathers but not in the sons. Sons showed less assertiveness and greater hostility overall; thus, restriction of the range of these variables may limit potential correlations with physiological measures in this group. Finally, although no family trends were observed, several of the adolescents did show extreme changes under stress, suggesting reactivity is a trait which is expressed early in life.

Adolescent↗
PubMed1990

Effects of exercise and exercise conditioning on blood platelet function.

The effects of exercise and exercise conditioning on blood platelet function were investigated in six healthy individuals who had not engaged in regular exercise for at least 1 yr prior to the study. The subjects (three men and three women) had a mean age of 28 (range 23-32) and participated in a supervised program of treadmill exercise. Subjects exercised for 20 min, three times weekly, for 12 wk at 70-80% of estimated maximum heart rate. Samples for platelet counts, platelet aggregation, and plasma beta-thromboglobulin (beta-TG) were obtained prior to training and after 6 and 12 wk of training. All subjects responded with an increase in aerobic capacity during training. Resting mean systolic and diastolic blood pressures decreased after training (P less than 0.05). Platelet counts increased after exercise, and the increment in week 12 exceeded that in the 1st wk by 57%. Platelet aggregation studies in platelet rich plasma (PRP) showed an increase in slope after exercise (week 1, P less than 0.05) which decreased with training (week 1 vs week 12, P less than 0.01). Aggregation studies utilizing impedance aggregometry in diluted native whole blood showed an acceleration of both spontaneous aggregation (P less than 0.01 weeks 6 and 12) and aggregation using epinephrine as an agonist (P less than 0.05) following exercise. Plasma beta-TG levels did not increase significantly after exercise; however, resting concentrations of beta-TG decreased with training (P less than 0.03).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

Physician awareness of elevated cholesterol.

Recent studies suggest a heightened awareness of the association between elevated cholesterol and heart disease. Physician awareness of an elevated cholesterol level was investigated at a university-affiliated, 200-bed community hospital. All cholesterol levels greater than 240 mg/dL on a multichemistry profile were evaluated regarding physician awareness. Criteria for awareness included any notation in the patient's chart indicating the physician's recognition of the abnormal cholesterol level or therapeutic intervention (dietary or pharmacologic). During March 1986, an awareness level of 20% was found. A similar review in March 1988 revealed no change despite a redefinition of the normal laboratory range of serum cholesterol from 133 to 298 mg/dL to 130 to 240 mg/dL. On April 12, 1988, a 1-hour lecture sponsored by the Physician Cholesterol Education Program was presented at a hospital general staff meeting. Physician cholesterol awareness rose to 51.6% for the remainder of April through May 1988, and was 48.3% at 6-month post-CME follow-up. Chart reviews showed no heightened physician awareness related to the patient's age, sex, or diseases secondarily associated with increased cholesterol; however, increased physician awareness was associated with the primary diagnosis of atherosclerotic vascular disease and severity of hypercholesterolemia. Physician awareness of an elevated serum cholesterol level was poor during two retrospective prevalence surveys but improved considerably after delivery of an educational program.

Awareness↗
PubMed1987

Cardiovascular changes during mental stress: correlations with presence of coronary risk factors and cardiovascular disease in physicians and dentists.

Stress may play a role in the etiology of cardiovascular disease. Research showing that mental stress administered in laboratory settings causes great change in cardiovascular and hemodynamic functioning supports this hypothesis. In a small sample of physicians and dentists, those who showed greater cardiovascular reactivity (hot reactors) to stress were more likely to be hyperlipidemic or to have had a myocardial infarction or coronary bypass surgery. In addition, some of the nonreactive group were hypertensives taking medication, which may have blunted their response to stress. Persons with higher cholesterol, higher triglyceride levels, and lower HDL levels all showed greater increases in blood pressure (BP) in response to stress. Also, the reactive group reported less emotional support and experienced greater numbers of family-related stressful events in the previous year. The degree of aerobic fitness influenced resting hemodynamics and percentage of body fat but not reactivity to stress. Likewise, smoking did not affect reactivity, but former smokers did have a significantly elevated total systemic resistance at rest. While it is impossible to say whether reactivity causes disease, is the result of the presence of risk factors and disease, or is caused by some other factor which also contributes to disease, these results suggest that the presence of cardiovascular reactivity to mental stress is a sign of potential illness and indicates the need for further medical and risk factor study of the patient.

Adult↗
PubMed1985

Elevated static pressure and pregnancy well-being.

Static pressure is defined as the pressure existing at all points in the circulation when the heart is stopped and is a determinant of cardiac output and blood pressure. By using the proposed relationship that static pressure = cardiac output X "resistance to venous return," estimates were made of peripheral static pressure in pregnant women. Measurements of cardiac output and venous resistance were accomplished with indirect plethysmographic techniques. Approximately 65% of pregnant women with complications had elevated values for their estimated peripheral static pressure. It is proposed that estimation of peripheral static pressure has both diagnostic and therapeutic applications in women with complications of pregnancy.

Blood Pressure↗
PubMed1985

Adrenergic innervation in the microcirculation of the bat wing.

The distribution of adrenergic nerves to the microcirculation of the wing web of the bat was studied in whole-mount preparations employing glyoxylic acid fluorescence histochemistry. A dense perivascular adrenergic nerve plexus consisting of various-sized nerve bundles surrounded the arteries. The accompanying veins were sparsely innervated by small nerve bundles or single axons. Arterioles also possessed a dense perivascular plexus comprised of a loose network of small axon bundles. Muscular venules accompanying most arterioles were supplied by a small number of varicose axons which surrounded these vessels in a loose network. The majority of the terminal arterioles were devoid of any direct innervation. The proximal segment of some terminal arterioles was innervated by one or two axons which were observed to diverge from the vessels and terminate in the tissue. The true capillaries, postcapillary venules, and lymphatics possessed no direct adrenergic innervation. Surgical sectioning of the appropriate nerve trunks or administration of 6-hydroxydopamine caused complete disappearance of all fluorescent adrenergic axons in the wing web. Faint acetylcholinesterase-positive staining was observed in a perivascular plexus surrounding the arteries and arterioles. A much diminished acetylcholinesterase activity was observed after treatment with 6-hydroxydopamine which implies that this enzymatic activity resides in the adrenergic nerves.

Animals↗
PubMedDate not supplied

Application of the MRFIT smoking cessation program to a healthy, mixed-sex sample.

The Multiple Risk Factor Intervention Trial (MRFIT) included a smoking cessation program that was highly successful (40.3% abstinence prevalence rate at 48-month follow-up) when used with other interventions for a male, middle-aged population at high risk for coronary heart disease (CHD). Our study employed the MRFIT cessation program alone with a mixed-sex, mixed-age, healthy population. We wished to determine its effectiveness when applied in a manner similar to other smoking cessation programs. Fifty-six subjects participated in a 10-week intervention followed by maintenance or extended intervention programs. The 52% abstinence prevalence rate at the end of the 10-week intervention dropped to 32% after four months, 25% at eight months, 25% at 12 months, and 27% at 16 months. The higher cessation rates of the original MRFIT study may be related to motivation and other characteristics of the high-risk population and to the combination of the smoking component with other interventions for CHD, rather than to the characteristics of the smoking intervention itself. Although the MRFIT program is comprehensive and includes vigorous maintenance activities, it is also expensive and may not be cost-effective or as desirable as programs with slightly lower cessation rates.

Adult↗