Biomedical subjects

W Riley

Publications and source records attributed to W Riley.

At least 19 recordsLinked to original sources

PubMed2004

Avian mortality events in the United States caused by anticholinesterase pesticides: a retrospective summary of National Wildlife Health Center records from 1980 to 2000.

We reviewed the U.S. Geological Survey National Wildlife Health Center (NWHC) mortality database from 1980 to 2000 to identify cases of poisoning caused by organophosphorus and carbamate pesticides. From the 35,022 cases from which one or more avian carcasses were submitted to the NWHC for necropsy, we identified 335 mortality events attributed to anticholinesterase poisoning, 119 of which have been included in earlier reports. Poisoning events were classified as confirmed (n = 205) when supported by findings of > or =50% inhibition of cholinesterase (ChE) activity in brain tissue and the detection of a specific pesticide in the gastrointestinal contents of one or more carcasses. Suspected poisonings (n = 130) were defined as cases where brain ChE activity was > or =50% inhibited or a specific pesticide was identified in gastrointestinal contents. The 335 avian mortality events occurred in 42 states. Washington, Virginia, and Ohio had the highest frequency of events, with 24 (7.2%), 21 (6.3%), and 20 (6.0%) events, respectively. A total of 8877 carcasses of 103 avian species in 12 orders was recovered. Because carcass counts underestimate total mortality, this represents the minimum actual mortality. Of 24 different pesticides identified, the most frequent were famphur (n = 59: 18%), carbofuran (n = 52; 15%), diazinon (n = 40; 12%), and fenthion (n = 17; 5.1%). Falconiformes were reported killed most frequently (49% of all die-offs) but Anseriformes were found dead in the greatest numbers (64% of 8877 found dead). The majority of birds reported killed by famphur were Passeriformes and Falconiformes, with the latter found dead in 90% of famphur-related poisoning events. Carbofuran and famphur were involved in mortality of the greatest variety of species (45 and 33, respectively). Most of the mortality events caused by diazinon involved waterfowl.

Acetylcholinesterase↗

PubMed2002

Efficacy and safety of valdecoxib in treating the signs and symptoms of rheumatoid arthritis: a randomized, controlled comparison with placebo and naproxen.

OBJECTIVE: To compare the efficacy of the COX-2 specific inhibitor valdecoxib with the conventional NSAID naproxen and placebo in treating rheumatoid arthritis (RA). METHODS: This multi-centre, randomized, double-blind, placebo-controlled trial compared the efficacy and safety of valdecoxib 10 mg (n=209), 20 mg (n=212) or 40 mg once daily (q.d.) (n=221) with naproxen 500 mg b.i.d. (n=226) or placebo (n=222), in treating the signs and symptoms of RA. Efficacy was assessed by the number of patients responding to treatment according to the American College of Rheumatology-Responder Index (ACR-20). RESULTS: ACR-20 response was recorded for all randomized patients who received a single dose of study medication (above). Valdecoxib, at all administered doses, produced significant improvements in the ACR-20 Responder Index at weeks 2, 6 and 12 compared with placebo (P<or=0.01). Valdecoxib and naproxen did not differ in terms of ACR-20 response rate and the three doses of valdecoxib were similar to one another. All three doses of valdecoxib were well tolerated. CONCLUSIONS: Single daily doses of valdecoxib 10, 20 and 40 mg demonstrated efficacy that was superior to placebo and similar to naproxen in treating the signs and symptoms of RA. All three doses provided similar levels of efficacy.

Administration, Oral↗

PubMed2001

Effects of ramipril and vitamin E on atherosclerosis: the study to evaluate carotid ultrasound changes in patients treated with ramipril and vitamin E (SECURE).

BACKGROUND: Activation of the renin-angiotensin-aldosterone system and oxidative modification of LDL cholesterol play important roles in atherosclerosis. The Study to Evaluate Carotid Ultrasound changes in patients treated with Ramipril and vitamin E (SECURE), a substudy of the Heart Outcomes Prevention Evaluation (HOPE) trial, was a prospective, double-blind, 3x2 factorial design trial that evaluated the effects of long-term treatment with the angiotensin-converting enzyme inhibitor ramipril and vitamin E on atherosclerosis progression in high-risk patients. METHODS AND RESULTS: A total of 732 patients >/=55 years of age who had vascular disease or diabetes and at least one other risk factor and who did not have heart failure or a low left ventricular ejection fraction were randomly assigned to receive ramipril 2.5 mg/d or 10 mg/d and vitamin E (RRR-alpha-tocopheryl acetate) 400 IU/d or their matching placebos. Average follow-up was 4.5 years. Atherosclerosis progression was evaluated by B-mode carotid ultrasound. The progression slope of the mean maximum carotid intimal medial thickness was 0.0217 mm/year in the placebo group, 0.0180 mm/year in the ramipril 2.5 mg/d group, and 0.0137 mm/year in the ramipril 10 mg/d group (P=0.033). There were no differences in atherosclerosis progression rates between patients on vitamin E and those on placebo. CONCLUSIONS: Long-term treatment with ramipril had a beneficial effect on atherosclerosis progression. Vitamin E had a neutral effect on atherosclerosis progression.

Aged↗

PubMed2001

An adaptive template-matching method and its application to the boundary detection of brachial artery ultrasound scans.

We developed an adaptive template-matching method for vessel wall boundary detection in brachial artery ultrasound (US) scans. The computer-aided identification of lumen-intima and media-adventitia boundaries of the brachial artery US scan is a critical step for flow-mediated vasodilator response measurement, which has become an increasingly important tool in both clinical and research applications. The adaptive template we propose in this paper is a combination of two parameterized Gaussian envelopes that approximates the US pulse envelope. The algorithm for template matching is cast as a constrained nonlinear least squares problem. A best match between the template and the observed US scan line signal results in a set of optimum parameters of the adaptive template, and the location of the boundaries is directly computed from these parameters. We present the results of applying our method to synthetic and clinical data, showing that the adaptive template-matching method provides superior accuracy in detecting the media-adventitia boundaries of both the near wall and the far wall of the vessel to that of conventional edge-detection methods.

Algorithms↗

PubMed2000

Effect of amlodipine on the progression of atherosclerosis and the occurrence of clinical events. PREVENT Investigators.

BACKGROUND: The results of angiographic studies have suggested that calcium channel-blocking agents may prevent new coronary lesion formation, the progression of minimal lesions, or both. METHODS AND RESULTS: The Prospective Randomized Evaluation of the Vascular Effects of Norvasc Trial (PREVENT) was a multicenter, randomized, placebo-controlled, double-masked clinical trial designed to test whether amlodipine would slow the progression of early coronary atherosclerosis in 825 patients with angiographically documented coronary artery disease. The primary outcome was the average 36-month angiographic change in mean minimal diameters of segments with a baseline diameter stenosis of 30%. A secondary hypothesis was whether amlodipine would reduce the rate of atherosclerosis in the carotid arteries as assessed with B-mode ultrasonography, which measured intimal-medial thicknesses (IMT). The rates of clinical events were also monitored. The placebo and amlodipine groups had nearly identical average 36-month reductions in the minimal diameter: 0.084 versus 0.095 mm, respectively (P:=0.38). In contrast, amlodipine had a significant effect in slowing the 36-month progression of carotid artery atherosclerosis: the placebo group experienced a 0.033-mm increase in IMT, whereas there was a 0. 0126-mm decrease in the amlodipine group (P:=0.007). There was no treatment difference in the rates of all-cause mortality or major cardiovascular events, although amlodipine use was associated with fewer cases of unstable angina and coronary revascularization. CONCLUSIONS: Amlodipine has no demonstrable effect on angiographic progression of coronary atherosclerosis or the risk of major cardiovascular events but is associated with fewer hospitalizations for unstable angina and revascularization.

Aged↗

PubMed2000

Hypertension and arterial stiffness: the Atherosclerosis Risk in Communities Study. ARIC Investigators.

Our objective was to describe the relationship of arterial stiffness and hypertension in a large, population-based sample of men and women. Hypertension-related increases in arterial stiffness may reflect the distending pressure and/or structural alterations in the artery. Included were 10,712 participants, ages 45 to 64 years, of the Atherosclerosis Risk in Communities Study, free of prevalent cardiovascular disease. Hypertension was classified as systolic or diastolic blood pressure (BP) > or =140/90 mm Hg, respectively, or the current use of antihypertensive medications. Common carotid arterial diameter change was measured using B-mode ultrasound and an electronic device that utilized radio frequency signals to track the motion of the arterial walls. Using statistical models to control for diastolic BP and pulse pressure, arterial diameter change was calculated separately in normotensive/ nonmedicated and medicated hypertensives. Hypertension was associated with a smaller adjusted diameter change (ie, greater stiffness) in comparison to optimal blood pressure (BP < 120/80 mm Hg): normotensive/nonmedicated men, 0.33 versus 0.43 mm (P < 0.001); medicated men, 0.34 versus 0.42 mm (P < 0.001); normotensive/ nonmedicated women, 0.34 versus 0.40 mm (P < 0.001), and medicated women, 0.33 versus 0.40 mm (P < 0.001). The relationship between pulse pressure and diameter change (ie, the slope of pulse pressure and diameter change) did not differ between hypertensives and normotensives. These cross-sectional data suggest that hypertension is associated with carotid arterial stiffness; however, these differences in the calculated stiffness appear to be the effect of distending pressure rather than structural changes in the carotid artery.

Age Distribution↗

PubMed2000

Training in assessment and appraisal: who needs it?

The aim of this project was to develop a training programme to help consultants supervising postgraduate medical trainees to fulfil their role as Educational Supervisors. A training needs analysis was conducted which revealed that consultants did not appreciate the importance of some of their new duties. This was mainly because of the lack of clear perception of their new roles. Hence training needs to be provided.

Education, Medical, Graduate↗

PubMed2000

Duplication of the hypophysis.

The authors describe an 11-year-old girl with duplication of a pituitary gland and hypertelorism. Of the 14 cases described to date, only 2 others have lacked associated major facial or oral anomalies. Two separate glands, respective stalks and hypothalamic enlargement were incidentally found on MR imaging performed to evaluate the patient's complaint of anosmia. A tortuous fusiform dilatation of one pericallosal artery was also discovered. A review of hypophyseal embryogenesis is presented. It is now evident that duplication of the pituitary can occur without other major dysmorphias. This may infer that notochord/prochordal plate deficits are not a prerequisite for hypophyseal duplication.

Cerebral Angiography↗

PubMed2000

Interactive multimedia preventive alcohol education: a technology application in higher education.

This article summarizes the process of implementation and short-term impact on knowledge and attitudes of an interactive multimedia software program on preventive alcohol education for young adults. The three factors related to behavioral change addressed in the software are self-efficacy in maintaining personal control and safety while using alcohol, attitudes and related expectations regarding the physiological and behavioral consequences of alcohol consumption, and peer norms regarding alcohol consumption. As compared to alternative alcohol education and a no-alcohol education groups, students using the interactive computer lesson reported learning more about dose-response and ways to intervene with friends in peril. The article concludes with consideration of the import of this technology for informing students about the consequences of alcohol use, and the utility to higher education institutions of using this technology in an era when pressures increase for due diligence around student safety but with few additional institutional resources.

Adaptation, Psychological↗

PubMed1999

Variability in ultrasonic measurements of arterial stiffness in the Atherosclerosis Risk in Communities study.

Arterial stiffness is emerging as an important risk marker for cardiovascular disease. Ultrasound-based measurements of arterial stiffness are in use by several large epidemiological studies. The reliability of ultrasonic measurements of arterial stiffness was assessed as part of one of these, the Atherosclerosis Risk in Communities (ARIC) study. ARIC, a prospective, four-center epidemiological study, used B-mode ultrasound with an electronic tracking device to measure arterial stiffness of the carotid artery. Oscillometric blood pressure measures were obtained before and after the arterial wall tracking. Measurement variability was estimated in 36 volunteers who were scanned at three visits conducted at 7- to 14-day intervals. Between- and within-person components of variation were estimated for arterial diameter and blood-pressure measurements. The correlation (R) between repeated measurements for pulse pressure, the percent change in arterial diameter (strain), and the percent and absolute change in the arterial area were 0.69, 0.67, 0.66 and 0.81, respectively. The R for the stress-strain elastic modulus (Ep), arterial distensibility, and arterial compliance were 0.66, 0.67, and 0.77, respectively. The R for the pressure-adjusted diameter change (i.e., diameter change adjusted for diastolic and pulse pressures) was 0.75. In summary, the ultrasonic measurements of arterial stiffness employed in the ARIC study demonstrate excellent short-term repeatability, demonstrating their utility in field settings.

Arteriosclerosis↗

PubMed1998

Neuroacanthocytosis and aprebetalipoproteinemia.

A 30-year-old woman presented with a progressive neurologic disorder characterized by seizures, buccolingual dyskinesias, orofacial tics, choreiform movements, atrophy, and areflexia. Investigations revealed normal lipid profile except for aprebetalipoproteinemia. Phase-contrast and electron microscopy showed 35 to 40% acanthocytes. MRI and 18fluorodeoxyglucose-PET studies showed caudate atrophy and hypometabolism. The phenotype of this patient is neuroacanthocytosis and its association with aprebetalipoproteinemia may represent a new subentity of the disorder.

Acanthocytes↗

PubMed1997

Rationale, design, and baseline characteristics of the Prospective Randomized Evaluation of the Vascular Effects of Norvasc Trial (PREVENT).

The Prospective Randomized Evaluation of the Vascular Effects of Norvasc Trial is the first angiographic clinical trial to be designed to test whether an agent can slow or even reverse the progression of early coronary atherosclerosis in patients with documented disease. In addition, a subset of patients are undergoing carotid ultrasound examinations, providing a unique opportunity to assess and correlate disease progression in 2 arterial beds.

Aged↗

PubMed1996

Risk factors and segment-specific carotid arterial enlargement in the Atherosclerosis Risk in Communities (ARIC) cohort.

BACKGROUND AND PURPOSE: B-mode ultrasound imaging affords the opportunity to quantify both intimal-medial thickness (IMT) and lumen diameter of extracranial carotid arteries in ambulatory populations. Since the relation of IMT to lumen diameter may be complex, we asked whether cardiovascular disease risk factors (previously shown to be associated with greater arterial IMT) are related to smaller lumen diameters. METHODS: We used B-mode ultrasound to quantify lumen diameter, interadventitial diameter, and IMT of the extracranial carotid arteries and assessed the relationship of these measures to body mass index, smoking, low-density lipoprotein (LDL) and high-density lipoprotein cholesterol, hypertension, and diabetes in 6088 male and 7493 female participants in the Atherosclerosis Risk in Communities (ARIC) cohort. RESULTS: Smoking, hypertension, and LDL cholesterol were consistently related to greater IMT in the common and internal carotid arteries of men and women, as has been previously reported. In the internal carotid artery, smoking, hypertension, and LDL cholesterol were consistently related to smaller lumens. In the common carotid artery, body mass index, smoking, and hypertension were related to significantly larger, and LDL cholesterol to smaller, lumens. Thus, only LDL cholesterol was consistently associated with smaller lumens in both the common and internal carotid arteries. CONCLUSIONS: Risk factors relate positively to IMT in both the common and internal carotid arteries and inversely with lumen diameter in the internal carotid artery, in parallel with their relation to clinical events. However, their association with lumen diameters of the common carotid artery in population-based samples is more complex, and in some cases adverse levels of risk factors may be associated with larger lumens.

Arteriosclerosis↗

PubMed1996

Factor structure of the 28-item general health questionnaire in a sample of antenatal women.

OBJECTIVE: The factor structure of responses to the twenty-eight-item General Health Questionnaire (GHQ-28) in a sample of 277 Nigerian antenatal women was examined. METHOD: Principal Component Analysis (PCA) and Varimax rotation were used. RESULTS: A four factor structure interpretable as social dysfunction, somatic-anxiety, depression-anxiety, and severe depression was obtained. CONCLUSION: Although the factor structure in this sample is similar to that previously reported with this instrument, the factor loadings particularly for the anxiety subscale differed. Thus, the factor structures of the GHQ may differ depending on the cultural background of the sample.

Adult↗

PubMed1995

Non-insulin-dependent diabetes mellitus and fasting glucose and insulin concentrations are associated with arterial stiffness indexes. The ARIC Study. Atherosclerosis Risk in Communities Study.

BACKGROUND: Cardiovascular diseases are the most common cause of disability and death among subjects with non-insulin-dependent diabetes mellitus (NIDDM). The atherosclerotic process begins during the prediabetic phase characterized by impaired glucose tolerance, hyperinsulinemia, and insulin resistance. In vitro studies have suggested that glucose and insulin can substantially alter the structure and function of the arterial wall and affect the development of atherosclerosis. METHODS AND RESULTS: We performed a cross-sectional study of the relation of arterial stiffness indexes with glucose tolerance and serum insulin concentrations. Several indexes of common carotid artery stiffness were assessed with noninvasive ultrasound methods in a biracial sample of 4701 men and women 45 to 64 years of age in the Atherosclerosis Risk in Communities (ARIC) Study. Arterial compliance (AC), stiffness index (SI), pressure-strain elastic modulus (Ep), and Young's elastic modulus (YEM) were calculated. YEM includes wall (intima-media) thickness and thus gives an estimate of arterial stiffness controlling for wall thickness. All indexes of arterial stiffness were higher with increasing concentrations of fasting glucose. This finding was consistent in both black and white examines and in both sexes. A 25% increase in fasting glucose (approximately 1 SD) was associated in nondiabetic white men with a 5.8% (95% CI, -9.6% to -1.9%; P = .004) decrease in AC and increases of 5.8% (95% CI, 2.0% to 9.7%; P = .002) in SI, 11.3% (95% CI, 6.9% to 15.9%; P < .001) in Ep, and 11.2% (95% CI, 6.2% to 16.6%; P < .001) in YEM. In nondiabetic white women, the corresponding predicted changes were a decrease of 15.0% (95% CI, -18.2% to -11.7%; P < .001) in AC and increases of 16.6% (95% CI, 12.5% to 20.8%; P < .001) in SI, 23.2% (95% CI, 18.4% to 28.2%; P < .001) in Ep, and 19.2% (95% CI, 14.0% to 24.7%; P < .001) in YEM. Glucose and insulin contributed synergistically to the increase in stiffness indexes. Insulin and triglycerides also had a synergistic association with stiffness indexes. CONCLUSIONS: Our findings are compatible with the view that persons with NIDDM or borderline glucose intolerance have stiffer arteries than their counterparts with normal glucose tolerance and that the decreased elasticity is independent of artery wall thickness. The joint effect of elevated glucose, insulin, and triglycerides can have a considerable impact on arterial stiffness and play an important role in the early pathophysiology of macrovascular disease in NIDDM.

Arteriosclerosis↗

PubMed1994

Arterial enlargement in the atherosclerosis risk in communities (ARIC) cohort. In vivo quantification of carotid arterial enlargement. The ARIC Investigators.

BACKGROUND AND PURPOSE: The relation between arterial wall (intimal-medial) thickness and lumen narrowing is complex and has previously been studied predominantly at autopsy. B-mode ultrasound affords the opportunity to visualize both wall and lumen of the extracranial carotid arteries in vivo. Several studies have quantified the relation of various independent variables to wall thickness of carotid arteries in population-based samples, but the relation of age and wall thickness to interadventitial and lumen diameter has not previously been investigated in these samples. METHODS: We used B-mode ultrasound to quantify the relation of arterial lumen diameter to age, arterial wall thickness, and arterial size (interadventitial diameter) of the extracranial carotid artery in 13,711 members of the Atherosclerosis Risk in Communities (ARIC) cohort. RESULTS: Men had greater interadventitial diameters, thicker walls, and wider lumens than women. Wall thicknesses of the common carotid artery were greater by 21% in men and 22% in women aged 60 to 64 years compared with those aged 45 to 49 years (P < .001). However, lumen diameters were also greater in older individuals because interadventitial diameters were greater. Wall thickness of the internal carotid artery was also associated positively with age, but the lumen diameter of the internal carotid artery was smaller in older individuals. Diameters of the carotid artery segments also differed in their relation to arterial wall thickening. The lumen of the internal carotid artery was uniformly progressively narrower with increasing wall thickness. For the common carotid artery greater wall thickness bore only a small correlation with narrower lumen diameter for thickening of the arterial wall up to 1.2 mm, but the association was more marked for the range of thicknesses between 1.2 mm and 2.5 mm. CONCLUSIONS: When arterial enlargement accompanies increased wall thickness, less lumen constriction results than expected. Quantification of these complex relations in vivo may provide new insight into the pathogenesis of symptoms related to vascular disease. Narrowing of the internal carotid artery lumen associated with thicker walls is consistent with the observation that stenosis develops in this region and often leads to symptoms.

Age Factors↗

PubMed1994

Relations of intimal-medial thickness among sites within the carotid artery as evaluated by B-mode ultrasound. ARIC Investigators. Atherosclerosis Risk in Communities.

BACKGROUND AND PURPOSE: B-mode ultrasound is a widely used technique for the clinical and epidemiological assessment of carotid atherosclerosis. This article describes the relation between arterial intimal-medial thickness (IMT) at different sites within the extracranial carotid artery. METHODS: IMT was measured by B-mode real-time ultrasound as an index of atherosclerotic involvement in the extracranial carotid arteries as part of the population-based Atherosclerosis Risk in Communities (ARIC) study. The relation between IMT at different sites was described by correlation coefficients and percentile regression techniques based on between 4034 and 9386 pairs of measurements (variation in sample size depending on the paired sites). RESULTS: Increased IMT at one site was associated with increased IMT at other sites. The correlation between right and left IMT at the same anatomic location in the carotid artery ranged from .34 to .49; the correlation at different anatomic locations in the carotid artery on the same side ranged from .25 to .43. The distribution of IMT, described by the percentiles of IMT at the inference site as a function of IMT at the index site, showed constricted percentiles of IMT at the inference site for small IMT at the index site and an increase in the spread of percentiles with increasing IMT. CONCLUSIONS: Although increased carotid IMT at one site is positively associated with thickened walls at other carotid sites, the ability to accurately predict wall thickness at a site given the wall thickness at other sites is modest. The general association between sites supports the systemic nature of atherosclerosis, while the lack of tight agreement between sites supports the focal nature of the atherosclerotic process.

Arteriosclerosis↗

PubMed1994

Islet cell antibodies predict insulin-dependent diabetes in United States school age children as powerfully as in unaffected relatives.

Islet cell antibodies (ICA) in the sera of nondiabetic relatives of patients with insulin-dependent diabetes (IDD) are predictive of the disease, a finding that permits the design of intervention strategies to prevent it. However, 85% or more of patients with new onset IDD have no affected relative. We therefore screened 9,696 schoolchildren between the ages of 5 and 18 yr (mean age 10.7 yr) in Pasco County, Florida for ICA in three surveys during 1984/5, 1987/8, and 1990/1 and have followed them prospectively. Approximately 4,000 of these children have been followed for nearly 8 yr. ICA titers > or = 10 Juvenile Diabetes Foundation units on replicate tests were detected in 57 of the children (0.59%). 10 children have developed diabetes so far, and all had ICA detected beforehand. The likelihood of developing IDD among the ICA-positive children was compared with 2,959 age-matched nondiabetic first degree relatives of IDD probands who were screened for ICA by our laboratory during the same time period and also followed prospectively. Of 103 (3.5%) ICA-positive relatives, 31 have developed IDD. Life table analysis reveals no statistically significant differences in the probability of developing IDD between the ICA-positive schoolchildren and ICA-positive first degree relatives (P = 0.3). The estimated risk of developing IDD by 7 yr in the ICA-positive schoolchildren was 45% (95% confidence interval 15-74%) compared with 43% (confidence interval 22-63%) in the relatives. We conclude that ICA appear to be as predictive of IDD in low-risk schoolchildren as they are in high-risk relatives. These data suggest that it is feasible to predict IDD by screening a general population of schoolchildren for ICA and that those found to be positive could be considered, in addition to relatives, for intervention protocols to prevent the disease.

Adolescent↗