Biomedical subjects
A Mitchell
Publications and source records attributed to A Mitchell.
Use of massive blood transfusions.
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Pentagonal aggregation of virus particles.
Virus aggregates with a unique fivefotd axis have been observed in the electron microscope.
Effect of meconium on the hemoglobin-oxygen association curve.
OBJECTIVE: Our purpose was to determine the effect of meconium-stained amniotic fluid on the hemoglobin-oxygen association curve of maternal whole blood. METHODS: Whole blood was obtained from term gravidas in active labor. Hemoglobin-oxygen association curves were generated for blood incubated with meconium vs. controls. Oxygen association curves were determined at pH 7.4 and 37 degrees C utilizing an automated device consisting of a spectrophotometer cuvette fitted with a magnetic stirrer, gas exchange line, and a Clark oxygen electrode. The samples were deoxygenated with nitrogen and association curves recorded while reoxygenating. Data was analyzed with Sigma Plot and Sigma Stat software. Analysis included log transformation, linear regression, and paired t-test. RESULTS: Twenty-eight hemoglobin oxygen association curves were generated. In all 14 pairs, meconium shifted the hemoglobin-oxygen association curve to the right. Partial pressures of oxygen required for various degrees of hemoglobin saturation were higher in meconium-exposed samples; P50 (30.1+/-0.6 vs. 27.8+/-0.4 mmHg, P < 0.01); P75 (46.9+/-0.6 vs. 43.1+/-0.5 mmHg, P < .001); P90 (69.2+/-1 vs. 63.3+/-1 mmHg, P < 0.01). CONCLUSIONS: Meconium-stained amniotic fluid causes a statistically significant, but clinically small, right shift in the hemoglobin-oxygen association curve.
The likelihood of remaining normotensive following antihypertensive drug withdrawal.
OBJECTIVE: To determine the proportion and characteristics of mild hypertensives who remain normotensive after withdrawal from drug treatment. DESIGN: Longitudinal descriptive study. SETTING: A university family practice unit (FPU) and a large steel company (DOFASCO) in Hamilton, Ontario. PATIENTS: Participants were 107 of 125 (86%) eligible hypertensives at the two sites; 103 (96%) subjects completed the study. INTERVENTION: Subjects discontinued antihypertensive medication and were followed until blood pressure (BP) became elevated or for 12 months, whichever was shorter. MEASUREMENTS AND MAIN RESULTS: BPs were monitored according to a predefined schedule and before, during, and after mental and physical stress tests. Thirty-eight (37%, 95% confidence interval [CI] 27-46%) subjects remained normotensive at 12 months. Predictors of remaining normotensive included lower medicated standing diastolic blood pressure (DBP) (87.6 versus 91.8 mm Hg, 95% CI for the difference 2.2-6.2, p less than 0.001) and longer duration of normotension on drugs (12.6 months versus 8.7, 95% CI for the difference 0.9-6.9, p = 0.012). There was no significant relationship between maintenance of normotension and age, medication potency, duration of hypertension, weight, lying BP, change in heart rate, or BP during mental or physical stress tests; the power to detect a clinically important difference in lying DBP was 99% but for other variables was lower (21-75%). CONCLUSIONS: The probability of hypertensives' remaining normotensive for one year after drug withdrawal increases as the medicated standing DBP decreases and as the number of months of BP control while on medication increases. Studies with larger sample sizes are warranted to determine whether other variables may be significant predictors.
Lipoprotein(a) and accelerated coronary artery disease in cardiac transplant recipients.
High concentrations of serum lipoprotein(a) (Lp(a)) are associated with an increased risk of atherosclerotic vascular disease in the nontransplanted population. However, its relation with accelerated coronary artery disease (CAD) in cardiac transplant recipients has not been reported. We measured serum Lp(a) in 130 cardiac transplant recipients undergoing routine follow-up, which included annual coronary angiography. The median Lp(a) concentration in 33 patients with CAD was 71 mg/dl, which was significantly higher than the corresponding value of 22 mg/dL in the 97 patients without CAD (p = 0.0006). Multivariant analysis showed the serum Lp(a) value to be a higher significant risk factor for CAD irrespective of the other factors included in the regression analysis. Thus a high concentration of serum Lp(a) is an important, independent risk factor for the development of accelerated CAD in transplant recipients.
Coronary calcification detected by ultrafast computed tomography is a predictor of cardiac events in heart transplant recipients.
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Long-term results of heart-lung transplantation for pulmonary hypertension.
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Influence of donor/recipient phenotype and degree of HLA mismatch on the development of transplant-associated coronary artery disease in heart transplant patients.
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Some determinants of attrition in prospective studies on aging.
Demographic measures, psychosocial variables, and objective and subjective measures of physical impairment were assessed in elderly men twice at intervals of 12 to 18 months. Canonical discriminant function analysis of the relationship between these predictor variables on the first testing and whether participants (a) returned for retesting, (b) did not return because of apparent disinterest, or (c) did not return because of illness or death, revealed two significant canonical variates. The first, characterized by decreased mental and physical capacity, discriminated between the deceased/ill group and the other two groups. The second was characterized by decreased social interaction and life satisfaction, and increased life events, and distinguished between the disinterested group and the other two groups. However, both groups that failed to return for retesting showed evidence of impaired physical health and a general disengagement from social and personal activities, compared to the retested group.
Tics, Tourette's, and attention deficit hyperactivity disorders: connections and treatment.
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Group B streptococcus and pregnancy: update and recommendations.
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Neonatal group B streptococcal disease.
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Mothers, infants, and DHA. Implications for nursing practice.
The purpose of this article is to describe the professional literature and current controversies concerning the relationship between essential fatty acids, especially Docohexaenoic Acid (DHA), and neurologic function. Although there is debate in the literature concerning just how much DHA is required for optimal neurologic functioning of infants, it is known that adequate DHA levels are dependent on an adequate dietary intake. However, common dietary practices today may not provide enough DHA. Because pregnancy and lactation are key times of rapid brain growth for the developing fetus and infant, nurses can be instrumental in teaching pregnant and lactating women diet-related information and promoting practices that help increase DHA levels. By understanding the importance of DHA in pregnancy and infancy, the nurse can take a more active role in essential health education.
Learner-centered group practice as a teaching model.
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Behavioral and physiological effects of a beta blocker and relaxation therapy on mild hypertensives.
In this industrial-based study we compared the blood pressure (BP)-lowering effectiveness of relaxation, a beta blocker, and the combined use of these two treatments in 47 untreated, mildly hypertensive blue collar steel workers. Using a randomized two by two factorial design, patients received either nadolol or placebo drug daily, and either a relaxation training or an education program, each lasting 8 weeks. A pre-intervention and post-intervention stress test measured response of heart rate and BP to mental and physical tasks. BP assessments were done at baseline, post-intervention, 1 month, and 3 month follow-up. Change in several self-report measures was determined. Results showed that beta blocker was more effective in lowering BP than placebo, but relaxation was not more effective in lowering BP than health education. The combined effect of beta blocker and relaxation was not superior to beta blocker alone. Compliance with relaxation practice was not superior to compliance with medication. We conclude that pharmacologic treatment is superior to the relaxation therapy tested.
Regulation of hepatic high density lipoprotein binding proteins after administration of simvastatin and cholestyramine to rats.
We investigated the regulation of putative high density lipoprotein (HDL) receptors in rat liver after cholesterol feeding and the administration of cholesterol-lowering drugs to rats. The expression of two plasma membrane HDL binding proteins (HB1 and HB2) were compared in control and treated livers by first separating membrane proteins on sodium dodecyl sulfate-polyacrylamide gels and quantitating HB1 and HB2 levels with a specific ligand blot assay. Of the various treatments used, only simvastatin or simvastatin plus cholestyramine produced significant changes, with reductions of up to 40% and 60%, respectively, for HB1 and HB2. The effect on the binding proteins was not associated with changes in serum cholesterol concentrations, which did not change significantly after either treatment, although a marked rise in liver cholesterol concentration after cholesterol was associated with a moderate increase in HB2 expression. We show evidence for regulation of the levels of hepatic HDL binding proteins and provide another important criterion for the acceptance of HB1 and HB2 as components of a functional HDL receptor.
Managed care and psychiatric-mental health nursing services: implications for practice.
Our current health care system is in a period of major change. To help control rising costs and improve management, health care reforms have been proposed, prompting the rapid development of managed care. The impact of managed care on the psychiatric-mental health system has become quite evident over the past few years with a resultant restriction of services, closing of inpatient units, and shift from inpatient to outpatient care. These cost control measures raise serious concerns regarding the quality and availability of necessary services. Managed care could have a devastating effect on the progress made in mental health treatment over the last 40 years if these issues are not addressed and remedied. The issue of how managed care influences mental health services is addressed, and implications for practice are presented.