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Biomedical subjects

R B Williams

Publications and source records attributed to R B Williams.

At least 19 recordsLinked to original sources
PubMed1992

Hostility during late adolescence predicts coronary risk factors at mid-life.

Hostility, as measured by the Cook-Medley Hostility Scale of the Minnesota Multiphasic Personality Inventory, has been found to predict higher rates of both coronary heart disease and all-cause mortality. To evaluate one mechanism whereby hostility might contribute to health problems, the authors used regression models to determine whether hostility measured in college (1964-1966) predicted coronary risk factors assessed 21-23 years later (1987-1990) in 4,710 men and women. Of this group, 828 had lipids measured (1988-1991). Persons with higher hostility scores in college were significantly more likely at follow-up to consume more caffeine (r = 0.043), to have a larger body mass index (r = 0.055), to have higher lipid ratios (r = 0.092), and to be current smokers (r = 0.069) than those with lower hostility scores during college. Cross-sectional analyses found significant associations of contemporaneous hostility scores with the same four risk factors, as well as with alcohol consumption and hypertension (rs ranging from 0.043 to 0.117). These associations are large enough to have possible public health significance. We conclude that hostility may contribute to health problems through its influences on several coronary risk factors across the adult life span.

Adult↗
PubMed1992

Differences between the anticoccidial potencies of monensin in maize-based or wheat-based chicken diets.

Experiments were carried out to investigate why the anticoccidial ionophore monensin is more potent against the coccidium Eimeria tenella in chickens fed on a maize-based diet (as in the USA) than in chickens fed on a wheat-based diet (as in the UK). The explanation seems to be that the pathogenicity of E. tenella is lower in maize-fed chickens than in wheat-fed chickens, whether monensin is present in the diet or not. Possible reasons for this are suggested. The better survival of maize-fed birds may be partly due to protective effects of the higher concentrations of vitamins A and E derived from their diet. Furthermore, the higher concentrations of niacin and riboflavin in wheat than in maize may enhance coccidial pathogenicity. These opposing factors might combine to cause equivalent infection levels to produce more severe coccidiosis in chickens fed on a wheat-based diet than on a maize-based diet.

Animal Feed↗
PubMed1992

Triaxial force transducer for investigating stresses at the stump/socket interface.

Although normal pressures at the stump socket interface of the lower-limb amputee have been investigated, little is known about the shear stresses that also occur. Studies suggest that the combination of both shear and normal stresses significantly exacerbates discomfort and vascular and tissue damage. A means of simultaneously measuring normal and shear stresses will aid in the investigation and improvement of prosthetic fit. A miniature triaxial force transducer (4.9 x 16 mm diameter) has been developed which can be recessed into the socket wall. The principle of operation, construction, performance and limitations of the device are described. Preliminary measurements of the interface stress variations over the gait cycle in a supra-condylar PTB socket are presented. These show clear differences in the stress patterns present when two different prosthetic feet are used.

Amputation Stumps↗
PubMed1992

Method for in-shoe shear stress measurement.

A methodology is described for use of a shear transducer, based on a magneto-resistive principle, to measure stresses under the plantar surface of the foot in-shoe during walking. Particular attention is paid to a projected application for study of diabetic plantar ulceration and its management by footwear. The transducer has a disc construction, approximately 4 mm thick by 16 mm diameter, and measures two orthogonal axes of shear simultaneously; this disc is mounted into an inlay that can be inserted into any stock orthopaedic shoe of the type commonly prescribed for diabetic foot problems. The transducer is located in the metatarsal head region of the inlay; exact placement of the transducer is determined by reference to the direct pressure distribution, the common method of palpation shown to be imprecise. Pilot trials on normal subjects are presented to evaluate the method.

Diabetic Neuropathies↗
PubMed1992

Using college alumni populations in epidemiologic research: the UNC Alumni Heart Study.

The UNC Alumni Heart Study (UNCAHS) is a prospective study of the role of psychosocial factors, in particular hostility, in the development of coronary heart disease. The target population is composed of persons who completed the Minnesota Multiphasic Personality Inventory while attending the University of North Carolina in the mid-1960s. Logistic regression analyses were used to determine whether hostility, demographic and other variables were significant determinants of the subjects' locatability and participation. It was found that MMPI hostility scores at initial testing were unrelated to either potential or actual locatability or participation. Thus there is no evidence that hostility is the source of selection bias in the UNCAHS. Selection into the study was predicted by age, sex, degree status and variables concerned with the conditions under which the MMPI was administered. It is concluded that follow-up studies of college cohorts may have study-specific sources of selection bias.

Adolescent↗
PubMed1992

Measures of neuroticism and disease status in coronary angiography patients.

A high percentage of patients who undergo diagnostic angiography because they have chest pain are found to be free of significant coronary artery disease. To examine the psychological characteristics of these patients, we used several Minnesota Multiphasic Personality Inventory (MMPI; Hathaway & McKinley, 1943) measures to assess the relationships between different aspects of neuroticism and coronary artery disease severity (CADSEV) in a sample of 1,462 angiography patients. The Conversion V profile was inversely and most strongly related to CADSEV. Single high scores on hypochondriasis or hysteria were also inversely related to CADSEV, but psychasthenia and Taylor Manifest Anxiety Scale (TMA; Taylor, 1953) scores were not. Using measures derived by a factor analysis of the MMPI, items relating somatic complaints were inversely related to CADSEV, but a measure of general neuroticism was not. These results support the hypothesis that the association between neuroticism and angiographic findings may be specific to a particular aspect of neuroticism, somatic preoccupation. The implications for neuroticism measurement and clinical practice are discussed.

Coronary Angiography↗
PubMed1992

Alpha-tocopherol, lipids and lipoproteins in knee-joint synovial fluid and serum from patients with inflammatory joint disease.

1. We have determined the antioxidant status of synovial fluid and serum of patients with inflammatory joint disease in terms of the biologically active lipid-soluble antioxidant, alpha-tocopherol. Synovial fluid concentrations of alpha-tocopherol were significantly lower relative to those of paired serum samples (P < 0.001). Serum levels of alpha-tocopherol in these patients did not differ significantly from those in control serum. 2. Lower concentrations of cholesterol, triacylglycerol and low-density lipoprotein were also observed in patients' synovial fluid compared with matched serum samples. However, multiple regression analysis of the data indicated that there remained a significant depletion of alpha-tocopherol, which was largely independent of these co-variables, in inflammatory synovial fluid. These findings are consistent with the consumption of alpha-tocopherol within the inflamed joint via its role in terminating the process of lipid peroxidation. 3. Nuclear magnetic resonance spectroscopic analysis of matched inflammatory synovial fluid and serum confirmed lower concentrations of triacylglycerol in synovial fluid together with evidence of a shortened mean triacylglycerol chain length. The latter metabolic difference suggests an increased utilization of triacylglycerols for energy within the inflamed joint.

Arthritis↗
PubMed1992

Exercise induced release of von Willebrand factor: evidence for hypoxic reperfusion microvascular injury in rheumatoid arthritis.

Experimental evidence suggests that rheumatoid synovitis may be perpetuated by the generation of reactive oxygen species during hypoxic reperfusion injury. The latter occurs because increased intra-articular pressure during exercise exceeds synovial capillary perfusion pressure, impairing blood flow. The object of this study was to establish a marker for and the mechanism of synovial hypoxic reperfusion injury. Von Willebrand factor (vWF) is only released from endothelial cells and platelets and is an in vivo and in vitro marker of endothelial injury. In vivo exercise induced changes in plasma vWF were therefore investigated in patients with rheumatoid arthritis (RA) compared with controls and in vitro vWF release by human umbilical vein endothelial cells subjected to hypoxia reperfusion. Pre-exercise plasma vWF levels were 1001 and 817 IU/l, increasing after exercise to 1658 and 845 IU/l in patients with RA and controls respectively. Von Willebrand factor release from human umbilical vein endothelial cells followed a biphasic pattern, occurring during both hypoxia and reperfusion. Hypoxia reperfusion induced vWF release by human umbilical vein endothelial cells in vitro suggests that exercise induced vWF release in patients with RA is best explained by synovial hypoxic reperfusion injury. This study supports evidence that generation of reactive oxygen species plays a principal part in synovial hypoxic reperfusion injury and suggests vWF as a useful marker of this phenomenon.

Adult↗
PubMed1992

Accentuated vagal antagonism of beta-adrenergic effects on ventricular repolarization. Evidence of weaker antagonism in hostile type A men.

BACKGROUND: Prior research has suggested a weaker parasympathetic antagonism of sympathetic effects on the heart in type A (coronary-prone) men. To confirm this phenomenon and extend our understanding of it, we investigated the effects of prior muscarinic blockade on the electrocardiogram T wave and other cardiovascular and neuroendocrine responses to isoproterenol in type A and type B (non-coronary-prone) men. METHODS AND RESULTS: Responses to two 5-minute intravenous isoproterenol infusions (0.01 micrograms/kg/min and 0.02 micrograms/kg/min) were evaluated in six type A and six type B men after pretreatment with either dextrose placebo or atropine (1.2 mg). Atropine significantly potentiated T wave attenuation in the recovery period after isoproterenol infusion (0.30 +/- 0.07 mV) compared with placebo (0.54 +/- 0.09 mV, p less than 0.001). Atropine also potentiated the heart rate increase to isoproterenol (39 +/- 3 beats per minute versus 20 +/- 2 beats per minute after placebo). Atropine enhanced decreases in systolic, diastolic, and mean arterial pressures as well as pulse pressure to isoproterenol. Atropine enhancement of many of these responses was increased among subjects with high scores on various hostility/anger scales. Isoproterenol alone produced greater T wave attenuation in type A than in type B men. However, atropine enhancement of T wave attenuation and blood pressure falls by isoproterenol was present only in type B men. CONCLUSIONS: These findings indicate that there is accentuated parasympathetic antagonism of T wave attenuation and blood pressure responses induced by beta-adrenergic stimulation. Relative weakness of this antagonism of sympathetic effects on the heart in hostile type A individuals may contribute to their higher coronary disease risk.

Adult↗
PubMed1992

Identification of patients with coronary disease at high risk for loss of employment. A prospective validation study.

BACKGROUND: Work disability is common in patients with coronary artery disease and adversely affects both economic well-being and quality of life. The purpose of this study was to construct a model to predict premature departure from the work force of patients with coronary disease and to validate this model prospectively in an independent cohort of patients. METHODS AND RESULTS: We enrolled 1,252 coronary disease patients referred for diagnostic cardiac catheterization who were less than age 65, employed, and without prior coronary angioplasty or coronary bypass surgery. Medical, functional, psychological, economic, and job-related variables were measured at the time of baseline diagnostic cardiac catheterization, and all patients were followed for 1 year. Three hundred twelve patients underwent percutaneous transluminal coronary angioplasty (PTCA) within 60 days of catheterization, and 449 had coronary artery bypass graft surgery (CABG) within 60 days of catheterization. The remaining 491 patients were treated with initial medical therapy. Logistic regression was used to develop a multivariable model for predicting 1-year work status in the training sample patients (872 patients enrolled between March 1986 and February 1989). This model was then validated in the independent prospective test sample (380 patients enrolled between March 1989 and June 1990). Eight factors were independent predictors of departure from the work force: lower initial functional status (as assessed by the Duke Activity Status Index), followed by older age, black race, presence of congestive heart failure, lower education level, presence of extracardiac vascular disease, poorer psychological status, and lower job classification. Standard clinical variables provided only 20% of the total predictive information available from the model about follow-up work outcomes, whereas functional measures provided 27%, and demographic and socioeconomic measures provided 45%. In the test sample, the area under the receiver operating characteristic curve for the model predictions was 0.74, compared with 0.80 in the training sample, and model predictions agreed well with observed prevalences of return to work. After adjustment for baseline imbalances, there was no significant difference in 1-year return-to-work rates among the patients receiving initial PTCA or CABG therapy versus initial medical therapy. CONCLUSIONS: Patients with coronary disease who are at high risk for premature departure from the work force can be accurately identified from a combination of medical and nonmedical risk factors. The model developed in this study provides a tool to identify patients at high risk for premature loss from the work force. Such patients may benefit from special multidimensional intervention programs designed to preserve work status. Our data show that revascularization with either PTCA or CABG is not, by itself, sufficient to accomplish this goal.

Angioplasty, Balloon, Coronary↗
PubMed1992

Reassessing the membership structure of ASHP.

In this discussion paper, the ASHP Board of Directors suggests that it is time for the American Society of Hospital Pharmacists to move to another stage in the development of its membership structure. In 1975, ASHP broadened its purview to represent pharmacists who practice in all types of organized health-care settings. The Board has observed that ASHP members today often identify more strongly with their specific practice type or specialty than with "hospital pharmacy" or "pharmacy practice in organized health-care settings." Further, such members prefer to engage in organizational activities with peers from their specific area of practice. This has led the Board to examine the membership structure of the Society in an effort to improve ASHP's effectiveness in exercising leadership for pharmacy practice in organized health-care settings. The Board suggests for consideration by ASHP members two types of changes in membership structure: (1) the creation of sections and (2) the establishment of affiliation arrangements with national organizations that share ASHP's orientation toward pharmacy practice in organized health-care settings. The Board recognizes that membership sections would have to be given substantial autonomy for them to be effective. The Board believes that a pilot or experimental approach should be used in making changes in membership structure, with explicit evaluation after a period of time. The Specialty Practice Group and Practice Management Group programs are also being reassessed by the Board. Finally, the full name of ASHP will be reconsidered.

Humans↗