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Biomedical subjects

H Taylor

Publications and source records attributed to H Taylor.

At least 73 records · Page 4Linked to original sources
PubMed1996

Ischemic, hemodynamic, and neurohormonal responses to mental and exercise stress. Experience from the Psychophysiological Investigations of Myocardial Ischemia Study (PIMI).

BACKGROUND: The pathophysiology of mental stress-induced myocardial ischemia, which occurs at lower heart rates than during physical stress, is not well understood. METHODS AND RESULTS: The Psychophysiological Investigations of Myocardial Ischemia Study (PIMI) evaluated the physiological and neuroendocrine functioning in unmedicated patients with stable coronary artery disease and exercise-induced ischemia. Hemodynamic and neurohormonal responses to bicycle exercise, public speaking, and the Stroop test were measured by radionuclide ventriculography, ECG, and blood pressure and catecholamine monitoring. With mental stress, there were increases in heart rate, systolic blood pressure, cardiac output, and systemic vascular resistance that were correlated with increases in plasma epinephrine. During exercise, systemic vascular resistance fell, and there was no relationship between the hemodynamic changes and epinephrine levels. The fall in ejection fraction was greater with mental stress than exercise. During mental stress, the changes in ejection fraction were inversely correlated with the changes in systemic vascular resistance. Evidence for myocardial ischemia was present in 92% of patients during bicycle exercise and in 58% of patients during mental stress. Greater increases in plasma epinephrine and norepinephrine occurred with ischemia during exercise, and greater increases in systemic vascular resistance occurred with ischemia during mental stress. CONCLUSIONS: Mental stress-induced myocardial ischemia is associated with a significant increase in systemic vascular resistance and a relatively minor increase in heart rate and rate-pressure product compared with ischemia induced by exercise. These hemodynamic responses to mental stress can be mediated by the adrenal secretion of epinephrine. The pathophysiological mechanism involved are important in the understanding of the etiology of myocardial ischemia and perhaps in the selection of appropriate anti-ischemic therapy.

Adult↗
PubMed1996

Extra-articular features of benign joint hypermobility syndrome.

To define the phenotype of patients with benign joint hypermobility syndrome (BJHS), we studied 58 consecutive patients (mean age 37 yr) presenting to a rheumatology clinic and 30 controls. Patients underwent rheumatological and ophthalmic examination, hypermobility scoring, echocardiography, measurement of bone mineral density (BMD), and skin thickness, elasticity and light transmissibility. The median hypermobility score was 5/9 Beighton and 31/56 Contompasis. Eighteen (31%) patients complained of significant arthralgia. Six (10%) patients and two (7%) controls had mitral valve prolapse (MVP) (chi(2) = 0.27, P = NS). Neither MVP nor aortic diameters showed a correlation with hypermobility score. There was no significant reduction in BMD. There was a significant correlation between hypermobility and light transmissibility of the skin (r = 0.71, P < 0.0001 Contompasis; r = 0.47, P < 0.05 Beighton) and skin stretchiness (r = 0.49, P < 0.05 Contompasis; r = 0.39, P < 0.05 Beighton). On ophthalmic examination, 14 (41%) patients had upper eyelid laxity. Thus, patients with BJHS do not have an increased prevalence of significant cardiac, bone, skin or eye abnormalities, helping differentiate BJHS from other more serious hereditary disorders of connective tissue.

Adolescent↗
PubMed1996

Tracking consumers' reactions to the changing health care system: early indicators.

A survey in fifteen communities and nationwide of consumers' opinions about changes in their local health care system reveals that Americans are surprisingly positive about recent changes in their personal access to and quality of care and consistently negative about changes in the cost of care. Although many consumers think that changes in the system are making things worse, they are optimistic about the trend toward managed care. Subgroup analysis shows that uninsured persons and persons with health problems reported high rates of concern about many of the health system issues we explored, while Medicaid recipients, Hispanics, and African Americans reported positive changes in their access to and quality of care.

Adult↗
PubMed1996

All payer, single payer, managed care, no payer: patients' perspectives in three nations.

We present data on patients' experiences with access to and cost and quality of health services in the United States, Canada, and Germany. In general, patients report favorably about their care. U.S. respondents report more problems with access to care, even controlling for the severe problems of the uninsured. Differences in managed care versus fee-for-service plans in the United States mirror some of the problems observed in international comparisons--access to specialists and tests and waiting times for and quality of some services. Different cost containment strategies have measurable effects on patients' perspectives, particularly among patients who are sicker.

Adult↗
PubMed1996

Organ specificity of antihypertensive therapy on ocular albumin vascular clearance and albuminuria in the hypertensive diabetic rat.

PURPOSE: The contributions of hypertension and diabetes to microvascular dysfunction in the kidney and eye were investigated. Two indices of microvascular dysfunction, urinary albumin excretion rate (AER) and albumin vascular clearance (AVC) in the eye, were studied in control and streptozocin diabetic Wistar Kyoto (WKY) and spontaneously hypertensive rats (SHR). METHODS: Studies were performed on four groups of untreated rats--nondiabetic and diabetic WKY and nondiabetic and diabetic SHR--and on three groups of diabetic SHR treated with a converting enzyme inhibitor (perindopril), a calcium-channel blocker (lacidipine), or triple therapy (hydrochlorothiazide, reserpine, and hydralazine). In all rats, AER and AVC were measured at 16 weeks. RESULTS: There was a progressive increase in both parameters in the order WKY, diabetic WKY, SHR, and diabetic SHR. When compared with nondiabetic WKY, diabetic SHR showed an approximately 30-fold increase in AER and an approximately threefold increase in AVC. Treatment of diabetic SHR with perindopril or triple therapy normalized AER compared to an equihypotensive dose of lacidipine, which had no effect. By contrast, the three antihypertensive regimens showed a different order of efficacy in preventing increases in ocular AVC. In diabetic SHR, the increase in retinal AVC was prevented largely by lacidipine, whereas the other two antihypertensive regimens showed lesser effects [AVC expressed as percentage nondiabetic WKY: untreated diabetic SHR 278% +/- 47%, lacidipine 93% +/- 10% (P < 0.001), triple therapy 132% +/- 37% (P < 0.05), and perindopril 167% +/- 9% (P < 0.05)]. Lacidipine also prevented the increase in AVC of the anterior and posterior uvea. By contrast, increases in AVC observed in the diabetic SHR were not prevented by perindopril in the posterior uvea or by triple therapy in the anterior uvea. Thus, hypertension and diabetes increased ocular AVC and AER, and effective antihypertensive therapy substantially prevented changes in both parameters. However, despite equivalent levels of blood pressure control for each regimen, discordant effects were noted on AVC and AER. Perindopril was associated with significantly lower AER than lacidipine, whereas lacidipine was more potent in preventing increases in ocular AVC. CONCLUSIONS: Results of this study suggest that different antihypertensive regimens in the diabetic rat may exert organ-specific effects on the retina and kidney despite equivalent effects on systemic blood pressure. These data also raise the possibility that retinal microvascular dysfunction in diabetes is ameliorated more readily by calcium-channel blockade than by converting-enzyme inhibition, whereas the reverse applies to renal microvascular dysfunction, as reflected by albuminuria.

Albuminuria↗
PubMed1995

Diminished expression of cell-surface complement regulatory proteins in HIV-infected children and with HIV infection of peripheral blood mononuclear cells in vitro.

Experimental data have established that HIV-infected lymphocytes activate the complement system. However, because mammalian lymphocytes possess a series of cell-surface complement regulators that inhibit amplification on autologous cells, complement-mediated destruction of host cells is usually inhibited. These studies were performed to examine whether alterations in the cell-surface complement regulatory proteins decay-accelerating factor (DAF, CD55) and membrane cofactor protein (MCP, CD46) may occur during HIV infection in vitro or in vivo. The physiologic significance of these alterations were assessed by radiolabeled chromium release experiments. We show that MCP fluorescent intensity is significantly lessened in HIV-infected children and that DAF intensity is similarly lessened in infected children with advanced disease. These findings could be duplicated with HIV infection of peripheral blood mononuclear cells in vitro.

Adult↗
PubMed1995

Complement activation and immune complexes in early congenital HIV infection.

Previous reports from our laboratory have shown that complement activation and the presence of circulating immune complexes are features of congenital human immunodeficiency virus (HIV) infection as they are in HIV-infected adults. The studies reported here were undertaken to (a) define whether complement activation is congenitally infected infants and children involves classic, alternative, or both pathways; (b) investigate the relationship between complement activation and circulating immune complexes; and (c) determine how early in congenital HIV infection complement activation and immune complexes can be found. We report that classic complement pathway activation and C1q-binding immune complexes can be found within the first 4 months of congenital HIV infection. However, the association between classic pathway activation and immune complexes before age 10 months was weak. These data raise interesting questions about complement-mediated immune complex processing in HIV-infected infants and young children.

Age Factors↗
PubMed1995

Ontogeny of rat myocardial A1 adenosine receptors.

Adenosine functions as a counterregulatory hormone in the myocardium by decreasing work and thereby protecting the myocardium against ischemia. Functional adenosine A1 receptors could serve as an important regulatory system in the developing preinnervated heart by balancing the humoral sympathetic input to the heart. The aims of this study were to determine if A1 adenosine receptors were functionally coupled to their Gi protein in the immature preinnervated heart and to determine if A1 adenosine receptors were present in greater numbers in the immature heart. One- to 3-day-old rat ventricular cardiomyocyte cultures were exposed to (1) control conditions; (2) isoproterenol, a beta-receptor agonist, (3) R-PIA, an A1 agonist, or (4) isoproterenol and R-PIA, cAMP levels were determined by RIA in each group. Adenosine A1 receptor density and the equilibrium dissociation constant were determined by binding of an adenosine A1 receptor antagonist in newborn, 1-week-old, 2-week-old, and adult rat hearts. A1 stimulation decreased the isoproterenol-induced increase in cAMP by 30%, demonstrating functional A1 receptors in immature preinnervated myocytes. The A1 receptor density in the newborn age group was twice the adult and 2-week-old level. We conclude that A1 receptors in the immature heart are functionally coupled to their effector and that A1 receptors are present in greater numbers in the immature heart.

Adrenergic beta-Agonists↗
PubMed1995

Recruiting for success--the potential for using occupational personality questionnaires for the assessment of doctors.

OBJECTIVES: to evaluate the Saville and Holdsworth Occupational Personality Questionnaire (OPQ) to assess its potential and validity as a tool in the recruitment of doctors. To determine the range of personality characteristics in a group of general practitioners. DESIGN: an administered commercially available questionnaire. SETTING: general practitioners in North and Mid. Stafftordshire. SUBJECTS: 133 general practitioners or trainees. RESULTS: 44% of general practitioners agreed to participate. The majority found it useful and recognised its potential to increase self-awareness, highlight weaknesses that might be improved and for future recruitment of others to their teams. Doctors' personality traits were similar to those of managerial/professional norms. The validity of the OPQ was supported by (a) significant associations with subjects' previously reported mental health problems and (b) 83% of respondents confirming that their reports correctly described their personalities at work. CONCLUSIONS: OPQs have a place in the recruitment of doctors by identifying appropriate people to strengthen the team.

England↗
PubMed1995

Regulatory responses of the coxal organs and the anal excretory system to dehydration and feeding in the spider Porrhothele antipodiana (Mygalomorpha: Dipluridae)

The roles of coxal and anal excretion in the regulation of haemolymph osmolality, [Na+] and [K+] were studied in the mygalomorph spider Porrhothele antipodiana (mass 0.7&shy;1.0 g) under differing conditions of feeding and hydration state. Dehydration of starved spiders by removal of drinking water caused progressive mass loss at a rate of about 2.5 % of initial body mass per day and was associated with increases in the whole-body [Na+] and [K+] and in the osmolality, [Na+] and [K+] of the haemolymph. On provision of prey, feeding partially restored this mass loss but further elevated body and haemolymph ion concentrations. Dehydration reduced fluid excretion by the anal excretory system and the four coxal organs in both starved and feeding spiders. Starved hydrated spiders initially produced anal urine at 5 &micro;l day-1 and this was progressively reduced to zero after 4 days of water deprivation. Spiders dehydrated to less than 12 % mass loss would nevertheless feed and this initiated a small post-prandial anal diuresis (<5 &micro;l day-1 compared with >30 &micro;l day-1 in fed hydrated spiders). Coxal fluid was produced by dehydrated spiders only during feeding and was delivered into the prey, the rate of production by single organs decreasing from about 19 &micro;l h-1 g-1 body mass in hydrated spiders to about 4 &micro;l h-1 g-1 body mass in spiders dehydrated to 11 % mass loss. There was an increase in urine [K+] and in the rate of anal K+ excretion associated with ad libitum feeding in dehydrated spiders. However, urine [Na+] and the rate of anal excretion of Na+ were not increased by feeding. This was associated with an increase in [K+] of the stercoral fluid above that observed in either fed or starved hydrated spiders, but no significant change in [Na+]. Conversely, [Na+] of the coxal fluid produced during feeding was increased by dehydration whereas [K+] was not. These observations are consistent with the previously postulated roles of the coxal organs (Na+) and anal system (K+) in the excretion of ions ingested with the prey. Full elimination of the prey ions was accomplished only after drinking water was resupplied, which initiated further anal and coxal diureses. Smaller anal and coxal diureses also occurred on rehydration of unfed spiders. The production of coxal fluid in the absence of prey is further evidence that the coxal organs have a true excretory function besides, presumably, assisting ingestion. During dehydration and feeding, P. antipodiana, unlike many insects, is unable simultaneously to conserve water and to eliminate ions by production of a highly concentrated excretory fluid. Both coxal fluid and anal urine were approximately iso-osmotic to the haemolymph and the urine was markedly hypo-ionic.

Journal Article↗
PubMed1995

Who has the best health care system? A second look.

A 1994 opinion survey again shows Americans less satisfied with their health care system than Canadians and (West) Germans are with theirs. Americans also report more problems in paying for care and receiving needed services. However, overall satisfaction in Canada and Germany has fallen. Important cultural differences between the countries were identified. Americans have higher expectations for medicine and a stronger preference for spending more nationally on health care. The most dramatic difference is Americans' antipathy to government. Public confidence in heads of U.S. federal health agencies is the lowest of any institution or agency in the three countries.

Budgets↗
PubMed1994

Hemodynamic and metabolic correlates of dipyridamole-induced myocardial thallium-201 perfusion abnormalities in multivessel coronary artery disease.

The mechanisms responsible for the development of reversible thallium-201 (TI-201) defects with dipyridamole stress in patients with coronary artery disease (CAD) is not well understood. Previous experimental animal studies have demonstrated coronary steal characterized by an absolute decrease in subendocardial flow distal to a stenosis in response to dipyridamole infusion. Accordingly, the purpose of this study was to determine if reversible TI-201 defects in response to dipyridamole infusion are reflective of myocardial ischemia or secondary to regional differences in flow reserve. Dipyridamole (0.56 mg/kg) TI-201 imaging was performed in 23 patients in whom serial electrocardiographic, hemodynamic, aortic and coronary sinus lactate, and coronary sinus adenosine measurements were obtained. All patients with CAD had TI-201 redistribution (3.8 +/- 2.0 defects/patient), and all patients without CAD had normal scans. Mean aortic pressure was similar in both groups and did not change in response to dipyridamole (non-CAD 103 +/- 11 vs CAD 99 +/- 15 mm Hg, p = NS). Pulmonary capillary wedge pressure was similar at baseline (non-CAD 11 +/- 4 vs CAD 13 +/- 5 mm Hg, p = NS) and did not change in response to the drug (non-CAD 14 +/- 3 vs CAD 15 +/- 7 mm Hg, p = NS). Lactate extraction fraction was similar at baseline (non-CAD 0.22 +/- 0.09 vs CAD 0.17 +/- 0.14, p = NS) and decreased similarly in both groups (non-CAD 0.08 +/- 0.06 vs CAD 0.05 +/- 0.12, p = NS).(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine↗
PubMed1994

Diagnoses, symptoms, and attribution of symptoms among black and white inpatients admitted for coronary heart disease.

OBJECTIVES: This study examined health care-seeking behaviors to elucidate factors that contribute to differences in patterns of coronary heart disease between African Americans and Whites. The prevalence of diagnosed coronary heart disease, patients' perceptions of symptoms and attribution of symptoms, and predictors of painful symptoms and attribution of cardiac symptoms were examined. METHODS: The study involved 2416 patients admitted with diagnoses of coronary artery disease, ischemic heart disease, or myocardial infarction or to rule out myocardial infarction. Structured interview questions were used to obtain demographic information, symptoms precipitating admission, and patients' attribution of their symptoms. Discharge diagnoses were obtained from hospital records. RESULTS: Acute myocardial infarction, unstable angina, nonacute ischemic heart disease, and atherosclerosis were more frequent in White patients. For Blacks, the odds of reporting painful symptoms were only 64% of the odds found for Whites when other factors were controlled, and the odds of attributing symptoms to cardiac origins were almost 50% lower for Blacks than for Whites. CONCLUSIONS: The tendency of Blacks to report fewer painful symptoms and to attribute their symptoms to noncardiac origins may contribute to differences in care-seeking and in medical management of heart disease in Blacks.

Black or African American↗
PubMed1994

Complement activation and immune complexes in children with polyarticular juvenile rheumatoid arthritis: a longitudinal study.

OBJECTIVE: To determine whether levels of either circulating immune complexes (IC) or complement activation fragments change as disease activity changes in children with polyarticular juvenile rheumatoid arthritis (JRA). METHODS: Twenty-six children with polyarticular JRA were examined over a time course of 4-21 months. Plasma complement activation fragments and IC were measured by commercially available enzyme linked immunoabsorbant assays. RESULTS: Both complement activation fragments and IC levels were lower in individual children when their articular disease was inactive. Children with persistently active disease had no change in any of these measures. CONCLUSION: Elevated levels of plasma IC and complement activation fragments are features of active polyarticular JRA. We believe our data support a role for the complement system in the pathophysiology of polyarticular JRA.

Adolescent↗
PubMed1993

Rheumatoid factor expression and complement activation in children congenitally infected with human immunodeficiency virus.

Rheumatic disease manifestations and autoimmune phenomena are common in adults infected with human immunodeficiency virus (HIV). On the other hand, rheumatic disease manifestations are rare in children congenitally infected with HIV. We studied the relationship between autoimmune phenomena and rheumatic diseases by examining HIV-infected children for the presence of rheumatoid factors (RFs), immune complexes, and complement activation fragments. RFs (principally IgA) were detected in 12 of the 24 HIV-infected patients (50%) and in none of the uninfected (HIV-exposed, seroreverted) controls (n = 22). Mean levels of complement activation fragments C3a and Bb were elevated in the HIV-infected children compared with the controls. A correlation was seen between the presence of IgA RF and alternative complement pathway activation as measured by plasma levels of Bb. None of the children had clinical or laboratory evidence of rheumatic disease.

Antigen-Antibody Complex↗
PubMed1993

A new community mental health team based in primary care. A description of the service and its effect on service use in the first year.

A new community multidisciplinary team based in primary care is described and the experience of the first year discussed. The effect the team has had on the use of psychiatric services in its first year was studied. There was a threefold increase in the rate of inception to care, leading to a doubling in the prevalence of treated psychiatric disorder. There has been a reduction in the demands made on the hospital out-patient services, but no change in the use of in-patient resources or emergency contacts.

Adult↗