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Biomedical subjects

L Wright

Publications and source records attributed to L Wright.

At least 19 recordsLinked to original sources
PubMed1992

Effect of serotonin and thromboxane A2 on blood flow through moderately well developed coronary collateral vessels.

This study was performed to determine whether thromboxane A2 (as the analogue U46619) and serotonin can cause vasoconstriction of moderately well developed coronary collateral vessels. Studies were carried out in seven adult mongrel dogs 2 to 4 months after embolic occlusion of the left anterior descending coronary artery had been performed to stimulate collateral vessel growth. At the time of study this artery was cannulated to determine interarterial collateral flow from measurements of retrograde blood flow. Radioactive microspheres were administered during retrograde flow collection to determine continuing tissue flow for evaluation of microvascular collateral communications. Serotonin (50 micrograms/min) resulted in a 48 +/- 11% decrease in retrograde flow (p less than 0.01), with a 36 +/- 10% decrease in total collateral blood flow (p less than 0.02). Infusion of U46619 (0.01 microgram/kg per min) caused a 38 +/- 13% decrease in retrograde blood flow (p less than 0.01), with a 34 +/- 13% decrease in total collateral flow (p less than 0.05). Serotonin caused a significant increase in tissue flow to the subepicardium of the collateral-dependent region, whereas U46619 caused no change in tissue blood flow. These data demonstrate that both serotonin and thromboxane A2 can cause vasoconstriction of interarterial coronary collateral vessels. The findings suggest that platelet activation in coronary arteries from which collateral vessels originate has potential for causing collateral vasoconstriction, thereby compromising blood flow to the dependent myocardium.

Animals↗
PubMed1992

A factor analytic study of physical risk variables for CHD.

The scores of 40 hospitalized male coronary heart disease (CHD) patients, for seven traditionally employed physical CHD risk factors, were subjected to a confirmatory factor analysis that employed a LISREL program. An attempt was made to confirm a two-factor solution that involved family history as one factor, and smoking, serum cholesterol level, blood pressure, physical exercise, diet, and weight control as the second. The obtained goodness-of-fit index (.84) suggests that the two-factor solution is a moderately valid one. These findings raise the question whether many of the physical risk factors for CHD simply may be manifestations of a single behavioral characteristic, perhaps best described as "lack of self-control."

Adult↗
PubMed1992

Are the physical and TABP risk factors for heart disease unique to CHD?

Scores of 40 hospitalized CHD patients on 11 Type A-related and 7 physical CHD risk factors were compared to those of 40 hospitalized non-CHD patients. Family history for CHD was the only physical risk factor for which a significant difference was found. CHD patients scored significantly higher on all seven interview-measured Type A and Type A subcomponent variables. Only two of the four Jenkins Activity Survey-measured Type A variables produced significant differences, with one higher for non-CHD subjects. It was concluded that some CHD risk scores also may be associated with other diseases, to the experience of being seriously ill, and/or to the experience of hospitalization.

Adult↗
PubMed1992

On the validity of an Augmented Structured Interview for measuring subcomponents of the Type A behavior pattern.

This study was designed to provide validity data for the Augmented Structured Interview (ASI), which has been developed to measure subcomponents (as opposed to the global) Type A behavior pattern (TABP). Eighty subjects from a large private southwestern medical center were administered a self-report measure of the TABP (the Jenkins Activity Survey--JAS) and the ASI. Forty of the subjects were being treated for post-infarction coronary heart disease (CHD). The remaining forty subjects did not possess documented CHD. The obtained ratings for all the six ASI-measured Type A subcomponents were significantly higher for the CHD than for the non-CHD group. A discriminant functions analysis revealed that the ASI was superior to the JAS in correctly classifying CHD and non-CHD subjects. These outcomes are interpreted as providing initial support for the validity of the ASI.

Adult↗
PubMed1992

The OPQ: a proposed instrument for predicting poisoning accident recurrence in young children.

A 26-item self-report questionnaire for parents/guardians was constructed for potential use with first-exposure childhood poisoning victims to predict high risk for subsequent poisoning episodes. Data were obtained from 185 subjects served by 1 of 5 US regional poison control centers. The resulting device was labeled the OPQ. Its retrospective validity (R = 0.71) and test-retest reliability (0.81) are viewed as sufficient. The test itself, with accompanying scoring key and norms, are provided here in the hope that other clinicians and researchers will join in subjecting the OPQ to prospective validity studies and other forms of Scale refinement.

Child, Preschool↗
PubMed1992

Macular disease in an elderly population.

In order to obtain more accurate information concerning the prevalence of macular diseases in an elderly population, a clinical study was undertaken on a sample of 430 members of the general population over the age of 65 years in London. Degenerative age-related macular changes were clinically visible in about 25%, and 2.8% had a lesion causing loss of visual acuity due to macular disease. Age was the only risk factor identified for age-related changes. No correlation was identified with the prevalence of hypertension, smoking, or diabetes mellitus between groups. In addition, symmetry was shown in the number of drusen, as well as their size, density and fluorescence in the central and peripheral areas between the eyes of affected subjects. The prevalence data from this study represent a baseline for the interpretation of hospital-based data and for the planning of health care.

Aged↗
PubMed1992

Newborn screening: the miracle and the challenge.

Modern newborn screening programs are coordinated multi-disorder systems for prevention of infant death and disability, which include statewide infant screening, rapid retrieval, early intervention, and long-term follow-up. Screening programs are dynamic, with new tests being evaluated and added. Because nurses are actively involved in all phases of newborn screening, they must be knowledgeable about each disorder and changing screening requirements. This article reviews basic defects, genetics, incidence, symptoms, treatment, and specific newborn screening requirements for the eight disorders most widely incorporated into statewide newborn screening programs, and discusses practical nursing interventions.

Anemia, Sickle Cell↗
PubMed1991

Induction of long-term survival of hamster heart xenografts in rats.

The aim of this study was to determine the mechanisms responsible for concordant xenograft rejection using the hamster-to-rat heart graft model. Even though it was known that rat CD4 positive T cells proliferated to hamster stimulators in mixed lymphocyte reactions, the depletion of CD4 positive T cells in rat recipients did not lead to an extension of xenograft survival. Suppression of T cell immunity using other monoclonal antibodies or cyclosporine also failed to improve survival. Only by depleting complement with cobra-venom factor could hamster xenograft survival be prolonged, and long-term survival was achieved by combining CsA with COF. High-antibody titers to hamster cells were found after transplantation of hamster hearts, and evidence is presented that rejection of these "concordant" xenografts is mediated primarily by antibody-complement mechanisms. The antihamster antibodies were produced in the absence of T cell help, which suggests that antibody-mediated graft destruction cannot be inhibited by suppression or depletion of T cells. Pharmacologic depletion of complement for the clinical application of concordant xenografts is a promising avenue of future research.

Animals↗
PubMed1991

Changes in hepatic glutathione metabolism in diabetes.

Glutathione is important in the regulation of the redox state, and a decline in its tissue level has often been considered to be indicative of increased oxidative stress in diabetes. In this study of diabetic rats, the level of hepatic glutathione was normal unless food intake was restricted. Thus, the previous report of a reduction in hepatic glutathione in diabetes is likely to be the result of food deprivation rather than diabetes alone. In contrast to changes characteristic of oxidative stress, the efflux of glutathione in bile from diabetic animals was significantly decreased, whereas hepatic mixed disulfides were unchanged, and the hepatic gamma-glutamyltransferase activity was considerably increased. These changes were not reproduced by food deprivation. The decrease in biliary excretion of glutathione in diabetes may reflect an attempt to conserve glutathione by activation of the hepatic gamma-glutamyl cycle. We conclude that the disturbances of glutathione metabolism in diabetes are not typical of those seen in oxidative stress or food restriction.

Animals↗
PubMed1991

Very low birth weight outcomes of the National Institute of Child Health and Human Development Neonatal Network.

This report describes the neonatal outcomes of 1765 very low birth weight (less than 1500 g) infants delivered from November 1987 through October 1988 at the seven participating centers of the National Institute of Child Health and Human Development Neonatal Intensive Care Network. Survival was 34% at less than 751 g birth weight (range between centers 20% to 55%), 66% at 751 through 1000 g (range 42% to 75%), 87% at 1001 through 1250 g (range 84% to 91%), and 93% at 1251 through 1500 g (range 89% to 98%). By obstetric measures of gestation, survival was 23% at 23 weeks (range 0% to 33%), 34% at 24 weeks (range 10% to 57%), and 54% at 25 weeks (range 30% to 72%). Neonatal morbidity included respiratory distress (67%), symptomatic patent ductus arteriosus (25%), necrotizing enterocolitis (6%), septicemia (17%), meningitis (2%), urinary tract infection (4%), and intraventricular hemorrhage (45%, 18% grade III and IV). Morbidity increased with decreasing birth weight. Oxygen was administered for greater than or equal to 28 days to 79% of less than 751-g birth weight infants (range between centers 67% to 100%), 45% of 751- through 1000-g infants (range 20% to 68%), and 13% of 1001- through 1500-g infants (range 5% to 23%). Ventilator support for greater than or equal to 28 days was given to 68% of infants at less than 751 g, 29% at 751 through 1000 g, and 4% at greater than 1000 g. Hospital stay was 59 days for survivors vs 15 days for infants who died. Sixty-nine percent of survivors had subnormal (less than 10th percentile) weight at discharge. The data demonstrate important intercenter variation of current neonatal outcomes, as well as differences in philosophy of care and definition and prevalence of morbidity.

Gestational Age↗