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Biomedical subjects

J F Wilson

Publications and source records attributed to J F Wilson.

At least 19 recordsLinked to original sources
PubMed1999

Endothelial function in Marfan syndrome: selective impairment of flow-mediated vasodilation.

BACKGROUND: The cardiovascular complications of Marfan syndrome arise due to alterations in the structural and functional properties of fibrillin, a constituent of vascular connective tissues. Fibrillin-containing microfibrils are closely associated with arterial endothelial cells, indicating a possible functional role for fibrillin in the endothelium. Plasma concentrations of endothelial cell products are elevated in Marfan subjects, which indirectly indicates endothelial dysfunction. This study directly assessed flow- and agonist-mediated endothelium-dependent brachial artery reactivity in Marfan subjects. METHODS AND RESULTS: In 20 Marfan and 20 control subjects, brachial artery diameter, blood flow, and blood pressure were measured by ultrasonic wall tracking, Doppler ultrasound, and photoplethysmography, respectively. Measurements were taken during hand hyperemia (a stimulus for endothelium-derived nitric oxide [NO] release in the upstream brachial artery) and after sublingual administration of the endothelium-independent vasodilator nitroglycerin. In 9 Marfan and 6 control subjects, the above parameters were also assessed during intra-arterial infusions of acetylcholine and bradykinin (agonists that stimulate NO production) and NG-monomethyl-L-arginine (L-NMMA, an inhibitor of NO production). Flow-mediated responses differed markedly between Marfan and control subjects (-1.6+/-3.5% versus 6. 50+/-4.1%, respectively; P<0.0001), whereas nitroglycerin produced similar vasodilation (14.2+/-5.7% versus 15.2+/-7.8%; P=NS). Agonist-induced vasodilation to incremental intra-arterial infusions of acetylcholine and bradykinin were not significantly different between Marfan and control subjects, and intra-arterial L-NMMA produced similar reductions in brachial artery diameter in both groups. CONCLUSIONS: These data demonstrate impaired flow-mediated but preserved agonist-mediated endothelium-dependent vasodilation in Marfan subjects and suggest preservation of basal NO release. Selective loss of flow-mediated dilation suggests a role for fibrillin in endothelial cell mechanotransduction.

Acetylcholine↗
PubMed1999

Housestaff workload and procedure frequency in the neonatal intensive care unit.

OBJECTIVE: To investigate the association of clinical workload and the decision to perform procedures on infants in the neonatal intensive care unit (NICU). DESIGN: Prospective cohort study over one academic year, observing infants exposed to housestaff working under various levels of clinical workload. SUBJECTS: All 31 housestaff rotating on the NICU service during the academic year 1993 to 1994 were observed. A total of 785 infants were admitted to these housestaff. SETTING: One academic Level III intensive care nursery. MEASUREMENTS AND MAIN RESULTS: Clinical workload was operationalized as number of NICU infants cared for by the individual houseofficer on-call each night. The procedures of interest were number of umbilical artery catheters (UACs), intubations, lumbar punctures (LPs), and peripheral phlebotomy performed by the houseofficer on-call. Using multiple linear regression approaches, controlling for the average severity-of-illness of each of the NICU infants, the experience and residency program of the houseofficer on-call, and the individual attending, we found that increased clinical workload (number of NICU infants) resulted in a significantly greater probability that an admitted infant received an umbilical artery catheter (p = .02), but resulted in less probability that any NICU infant received a lumbar puncture (p = .0001) or peripheral phlebotomy (p = .0002). The decision to intubate an infant was not affected by the workload in the NICU. CONCLUSIONS: The clinical workload of housestaff in the NICU can affect decisions to perform procedures on infants in the NICU. For equivalently severely ill infants, there is a greater chance of receiving a UAC and less chance of being phlebotomized or receiving an LP when workload is high. Attending neonatologists need to be sensitive to possible effects of workload on patient care in the NICU.

Analysis of Variance↗
PubMed1999

Precision and accuracy of the measurement of antiepileptic drugs in South Africa.

The accuracy and the precision with which a drug concentration is quantified in the blood has a significant impact on the therapeutic drug monitoring (TDM) of the drug. In the absence of a system of accreditation of laboratories in South Africa, this study was designed to compare the accuracy and the precision of the measurement of antiepileptic drugs by 24 South African laboratories with those of non-South African laboratories that participate in the United Kingdom National External Quality Assessment Scheme (UKNEQAS). Three test samples, containing a range of concentrations of phenytoin, valproate, carbamazepine, and phenobarbitone spiked into newborn calf serum were distributed to participating laboratories, which were asked to measure the serum concentrations using their routine assay method. Coefficients of variation were used to assess precision of measurements, and the percentage difference of the consensus mean from the spike value was used as an assessment of accuracy. There was comparable precision in the measurements for both the South African and the non-South African groups. However, there appeared to be a difference in the accuracy of measurement between the two groups. It was noted that the majority (77%) of the South African laboratories used the Abbott fluorescence polarization immunoassay (FPIA) with TDx analyzers (Abbott Laboratories, Abbott Park, IL, USA). Further analysis of the results of the South African and UKNEQAS subgroups using the FPIA technique showed a reduction in statistic bias, suggesting that part of the explanation for the statistic difference in the accuracy may be an intertechnique bias related to the use of a nonhuman matrix for sample preparation. Additional studies are required to determine other causes for the statistic differences in accuracy. However, the differences in accuracy are unlikely to be of clinical significance.

Animals↗
PubMed1999

Sex differences in route learning by children.

Differences between men and women have been reported with respect to route-learning, but sex differences in children on these and related tasks have not been found. In this study, 51 children ages 5 to 12 years were required to learn a route on a map to criterion and then asked to recall landmarks on that route. Boys made significantly fewer errors and took less time and fewer trials to reach criterion in learning the route, and girls recalled more landmarks than boys. Significant main effects for age were also noted on all measures of route learning and landmark recall. These results suggest that the patterns of route learning that have been ascribed to women and men are present in girls and boys.

Age Factors↗
PubMed1998

Nitric oxide enhances the inotropic response to beta-adrenergic stimulation in the isolated guinea-pig heart.

Nitric oxide (NO) exerts several effects on myocardial contraction, including enhancement of relaxation and diastolic function, modulation of beta-adrenergic inotropic responses, and inotropic effects in the absence of agonist pre-stimulation. Different effects have been observed in different species and preparations, and it is unclear whether they are species- or preparation-specific, or whether they represent a range of responses that can manifest in most mammalian species. We therefore examined the effects of NO on the inotropic response to beta-adrenergic stimulation in the isolated guinea-pig heart, a species in which we have previously shown that NO enhances basal left ventricular (LV) relaxation and modulates the Frank-Starling response. Isolated ejecting hearts were perfused with Krebs buffer at constant placed heart rate (1 microM) indomethacin, 37 degrees C, constant loading conditions), and high fidelity LV pressure was monitored by an apical 2 F Millar catheter. All hearts were initially treated with dobutamine (0.1 microM) and then, once the peak inotropic and chronotropic response had been established, with either (a) no further treatment (n = 6), (b) the NO donor sodium nitroprusside (1 microM, n = 6; 10 microM, n = 6), or (c) the specific agonist for NO release, substance P (0.1 microM, n = 6). Dobutamine (0.1 microM) produced a rapid positive inotropic and chronotropic response, associated with a fall in LV end-diastolic pressure (LVEDP) and a rise in coronary flow. The positive inotropic effect of dobutamine declined over 20-28 minutes, while the chronotropic response persisted over this period. Low dose sodium nitroprusside (1 microM) delayed the decline in the inotropic response to dobutamine and exaggerated the fall in LVEDP. Similar effects were observed with substance P (0.1 microM). In contrast, a higher dose of sodium nitroprusside (10 microM) did not alter the response to dobutamine. These data indicate that "low dose" NO augments the inotropic response to beta-adrenergic stimulation in the isolated ejecting guinea-pig heart, in addition to its previously reported effects on basal LV relaxation in the same preparation.

Adrenergic beta-Agonists↗
PubMed1998

Personality and social competency following unilateral stroke.

Neuropsychological research indicates that the left hemisphere plays a dominant role in verbal production and processing, while the right hemisphere plays a dominant role in nonverbal production and processing. This study sought to examine the effects of such differential hemispheric specialization on personality and social competency. Ten left hemisphere damaged (LHD) stroke patients, 11 right hemisphere damaged (RHD) stroke patients, and 7 neurologically normal (NHD) patients were videotaped while engaging in social interaction with their spouse and an interviewer. Segments of the interactions were independently coded by two observers. Patients and spouses were rated with respect to their level of social competency and the extent to which they were characterized by 10 personality adjectives (e.g., outgoing, warm). Ratings for the personality items were summed to create an aggregate score. Analysis of these scores revealed both LHD and RHD patients to have lower (i.e., more negative) mean scores than NHD patients, suggesting that stroke patients as a whole were seen as socially impaired. Analysis of the socially competent item revealed particular LHD deficits; LHD patients were seen as less socially competent than both RHD and NHD patients. Spouses of LHD, RHD, and NHD patients, in contrast, did not differ in observer-rated social behavior.

Cerebrovascular Disorders↗
PubMed1998

Physical symptoms, distress, and breast cancer risk perceptions in women with benign breast problems.

Physical symptoms, general and breast cancer-specific distress, and perceived breast cancer risk were assessed in 66 women with benign breast problems (BBP) and 66 age-matched healthy comparison (HC) women. BBP women reported significantly greater worry about breast cancer than HC women. Breast symptom incidence and breast cancer risk perceptions were found to mediate group differences in breast cancer worry. Hierarchical regression analyses indicated that perceptions of control over a potential breast cancer prognosis moderate the impact of breast symptoms on reports of breast cancer worry. Implications for risk counseling with BBP women are discussed.

Adult↗
PubMed1998

Comparing fourth-year medical students with faculty in the teaching of physical examination skills to first-year students.

PURPOSE: To see whether fourth-year medical students can teach the physical examination to first-year students as effectively as can faculty preceptors. METHOD: Ninety-three first-year students studying the physical examination were randomly assigned to one of ten fourth-year student preceptors or one of 15 faculty preceptors. Test results and course evaluations were compared by type of preceptor. Fourth-year student preceptors were surveyed regarding their experience. RESULTS: The mean test scores did not differ between the first-year students with fourth-year student preceptors and those with faculty preceptors. The first-year students rated the fourth-year student preceptors higher than they did the faculty preceptors. The fourth-year students rated their experience favorably. CONCLUSION: A select group of fourth-year medical students provides a successful alternative to faculty in the teaching of the physical examination to first-year students.

Attitude↗
PubMed1998

The effect at one teaching hospital of interns' workloads on the satisfaction of their patients.

PURPOSE: To explore whether the amount of workload of first-year residents (interns) affects the satisfaction of their patients. METHOD: The authors collected data from January through May 1995 for 145 patients admitted to Lexinton Veterans Affairs Medical Center with the primary diagnosis of chronic obstructive pulmonary disease (COPD) or congestive heart failure (CHF). Workload was measured as the number of other patients for whom the intern had primary responsibility on the day of the studied patient's admission. A questionnaire measured the patients' satisfaction on the day of discharge. The authors analyzed the data using Pearson correlation and multiple linear regression. RESULTS: For the 89 patients with COPD (controlling for patient age, severity of illness, and sex of intern), greater workloads for their interns was a significant predictor of decreased patients' satisfaction (p = .001). No association was found for the 56 patients with CHF. CONCLUSION: Interns' workloads on the day their patients are admitted can influence their patients' subsequent satisfaction.

APACHE↗
PubMed1998

An audit of therapeutic drug monitoring service provision by laboratories participating in an external quality assessment scheme.

Therapeutic drug monitoring services were investigated in a questionnaire sent to all subscribers to the United Kingdom National External Quality Assessment Scheme for Therapeutic Drug Assays. Questions were posed on assay availability and use, target ranges, and reporting procedures for digoxin, lithium, phenytoin, phenobarbitone, carbamazepine, theophylline, and valproic acid. One hundred fifty-seven laboratories replied and, except for lithium, 45% reported in mass units, 34% in molar units, and 22% a mixture of mass and molar units. Target ranges for lithium, digoxin, carbamazepine, and phenobarbitone were highly variable but ranges for phenytoin, theophylline, and valproic acid were more consistent. Immunoassay was the most popular methodology although high-performance liquid chromatography was commonly used for anticonvulsants. Paper copies of results were provided by 93% of laboratories, 40% reported by telephone, 12% by fax, and 28% by computer. Additional data, mainly dose, time of last dose, and duration of therapy were requested by 55% to 67% of laboratories. Grades of staff authorizing results ranged from nurses to senior consultants, and collaboration with pharmacists occurred in 26% of laboratories. Most laboratories provided a daily analytical service and 73% offered a 24-hour emergency service. This audit unexpectedly identified use of a wide range of target concentrations, particularly for digoxin and lithium.

Drug Monitoring↗
PubMed1998

A randomized trial of providing house staff with patient social history information. Effect on patient outcomes.

The purpose of this project was to assess if providing physicians (house staff) with routine comprehensive social history information on their patients will improve patient outcomes. Comprehensive social history information was gathered over a 5-month period on 134 consecutive patients. Patients were randomized to have social history information provided or not provided to the resident physician caring for them. Outcomes of interest were: patient satisfaction, length of stay, and early unplanned readmission. Analysis was with analysis of covariance, controlling for patient severity of illness and amount of social history information documented by the house officer. Outcomes were the same for patients for whom house staff were provided social history information versus those for whom the information was not provided. The authors conclude that providing house staff with routine comprehensive social history information did not influence patient outcomes.

Aged↗
PubMed1998

Quantitation of carboxyhaemoglobin in blood: external quality assessment of techniques.

The performance of four dedicated carbon monoxide (CO)-oximeters (AVL, Chiron, IL, Radiometer), spectrophotometry with and without dithionite, spectrophotometry by second derivative, and the Whitehead and Worthington precipitation technique for the measurement of carboxyhaemoglobin in blood was compared by a mean of 136 participants in the United Kingdom National External Quality Assessment Scheme in 21 samples formulated to contain from 4% to 48% carboxyhaemoglobin. The dedicated instruments and spectrophotometry by second derivative were of significantly higher precision than the other techniques, producing fewer measurements rejected as being > 3 standard deviations from the sample mean and having a lower standard deviation for non-rejected measurements. The AVL instrument and spectrophotometry by second derivative had a significant positive bias compared to the other techniques. The Whitehead and Worthington method was of an unacceptably low precision.

Carbon Monoxide Poisoning↗
PubMed1998

Sexing of human and other primate DNA.

We present a rapid and simple method for the sexing of human and other primate DNA. Homologous introns from the X- and Y-linked zinc finger protein genes (ZFX and ZFY) are PCR amplified with one primer pair. An Alu element insertion in the ZFX intron results in a size difference in the amplicons which is resolved by agarose gel electrophoresis.

Animals↗
PubMed1997

Hair analysis as a potential index of therapeutic compliance in the treatment of epilepsy.

Twenty-three patients resident at the Chalfont Centre for Epilepsy, who have been prescribed carbamazepine either as monotherapy or in combination with other antiepileptic drugs have been monitored for a period of 6 months. Monthly hair samples along with concomitant plasma samples have been collected over this period and the 1 cm from scalp hair sections and the plasma concentrations of carbamazepine measured. The relationship between dose, hair and plasma concentrations have been assessed as well as the monthly variability in the concentration of carbamazepine in both matrices.

Anticonvulsants↗
PubMed1997

Clinical indications for brachytherapy.

Brachytherapy, or placing radioactive sources either temporarily or permanently into or near a malignant tumor, is a long-established cancer treatment method. During the past 25 years, brachytherapy has become safer and more versatile than earlier radium therapy, and its indications have increased dramatically during this period. One estimate is that at least 5-10% of all patients needing radiation therapy require brachytherapy. The site-specific clinical indications and methods for brachytherapy implementation are described.

Biliary Tract Neoplasms↗