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Biomedical subjects

G W Evans

Publications and source records attributed to G W Evans.

At least 19 recordsLinked to original sources
PubMed1992

Rapid intravenous infusion of amphotericin B: a pilot study.

PURPOSE: The administration of amphotericin B in the conventional prolonged infusion over 4 to 6 hours is complicated by the acute toxicities of fevers and chills in 50% to 90% of patients and the chronic toxicities of increased creatinine levels and hypokalemia in 60% to 80% of patients. To determine the safety and toxicity of rapid infusions, we conducted a prospective, nonrandomized study in patients with clinical indications for antifungal therapy. PATIENTS AND METHODS: Twenty-five granulocytopenic adults with acute leukemia and myelodysplastic syndromes were enrolled in a phase I trial using four sequentially shorter infusion durations: a standard infusion over 4 hours (n = 3) and shortened infusion durations at 3 hours (n = 3), 2 hours (n = 4), and 1 hour (n = 15). Toxicity was assessed by daily examinations of study subjects by one of the study investigators, by documentation of all infusion-related fevers and chills, and by daily monitoring of serum levels of creatinine, potassium, magnesium, and aspartate aminotransferase. RESULTS: Temperatures greater than 38 degrees C occurred in 16 of 25 (64%) patients, but only two had temperatures exceeding 40 degrees C. Chills were observed in 13 of 25 (56%) patients, but only one had severe symptoms. Serum creatinine increased more than 0.5 mg/dL (44.20 mumol/L) above the pretreatment baseline in 17 of 25 (68%) patients, and the absolute creatinine level was greater than or equal to 2.0 mg/dL (176.8 mumol/L) in 10 of 25 (40%) patients. Serum potassium levels dropped below the normal limit of 3.5 mEq/L (3.5 mmol/L) in all patients, but no patient had potassium levels below 2.5 mEq/L (2.5 mmol/L). Intravenous potassium supplementation was administered to all patients and exceeded 100 mEq/d in 12 of 25 (48%) patients. CONCLUSIONS: Rapid infusions of amphotericin B are safe, are associated with similar toxicity as prolonged infusions, and facilitate inpatient care by decreasing nursing time needed for administration and minimizing scheduling conflicts with other necessary intravenous medications. Shorter infusions also facilitate outpatient and home administration of amphotericin B.

Aged↗
PubMed1992

Chromium picolinate increases membrane fluidity and rate of insulin internalization.

The effects of chromium chloride, chromium nicotinate, and chromium picolinate on insulin internalization in cultured rat skeletal muscle cells was examined. Insulin internalization was markedly increased in cells cultured in a medium that contained chromium picolinate and the increased internalization rate was accompanied by a marked increase in the uptake of both glucose and leucine. The effect was specific for chromium picolinate since neither zinc picolinate nor any of the other forms of chromium tested was effective. The increased insulin internalization rate may result from an increase in membrane fluidity since chromium picolinate and to a lesser extent, chromium nicotinate, increased the membrane fluidity of synthetic liposomal membranes.

Animals↗
PubMed1992

Ultrasonic measurement of the elastic modulus of the common carotid artery. The Atherosclerosis Risk in Communities (ARIC) Study.

BACKGROUND AND PURPOSE: The Atherosclerosis Risk in Communities Study is a prospective investigation of the etiology and natural history of atherosclerosis and the etiology of clinical disease in four US communities. METHODS: Noninvasive ultrasonic methods were used to determine mean wall thickness (WT), radius (R), and circumferential arterial strain (CAS) in the left common carotid artery of 3,321 white male and female study participants between the ages of 45 and 64 years. The mean and standard deviation of Young's elastic modulus (Y) in 5-year age groups were determined for each sex by combining the ultrasonic data with concurrent noninvasive measurements of pulse pressure (PP) in the right brachial artery using the equation Y = (R/WT) x (PP/CAS). RESULTS: Significant (p = 0.0001) age group differences in Y were observed in both sexes, with the mean value increasing from 701 kPa in women and 771 kPa in men in the 45-49-year-old age group to 965 and 983 kPa, respectively, in the 60-64-year-old age group. Significant (p = 0.0001) age group differences were also observed for WT, the WT/R ratio, PP, CAS, and the PP/CAS ratio in both sexes. A sex difference in Y was detected (male greater than female, p = 0.0006) only in the 45-49-year-old age group. Significant (p less than 0.0001) sex differences were found, with men having a greater lumen diameter calculated as 2 x (R - WT), a greater WT, and a greater 2R in all age groups. The WT/R ratio did not differ in both sexes in all age groups. CONCLUSIONS: Knowledge of the arterial wall elastic modulus and the parameters required for its determination can provide important insight into structural changes occurring within the arterial wall with age and sex, and possibly with the onset of very early arterial disease.

Aging↗
PubMed1991

Daily hassles and chronic strains: a hierarchy of stressors?

Among 105 poor, male heads of household in an urban center of India, common daily hassles were similar to those experienced by individuals from economically advantaged, western countries. However, we did not replicate the correlation between hassle frequency and mental health problems that has been previously found in a middle-class, western sample. In contrast to daily hassles, which include low-intensity, relatively discrete stressors (e.g. disagreement with spouse, missing a bus), chronic strains include ongoing social and environmental conditions that represent high-intensity stressors (e.g. substandard housing, inadequate access to water) that threaten survival. We found that chronic strains were associated with greater levels of psychosomatic symptomatology, as well as lower perceived social support. Furthermore, the correlation between chronic strains and psychosomatic symptoms increased when the effects of income were statistically controlled, suggesting that income attenuates the effects of chronic strains and that chronic strains affect symptoms independent of income. In sum, chronic strains may be a more valid and potent stressor than daily hassles in poor, urban populations in developing countries.

Adult↗
PubMed1991

Dynamic role of social support in the link between chronic stress and psychological distress.

How a chronic environmental stressor can interfere with the buffering effects of social support by eroding social support was analyzed in this prospective, longitudinal study. A classic buffering effect of support was found after 2 months of exposure to the stressor, household crowding. Crowded residents with low perceived support had greater increases in psychological distress than did crowded residents with high perceived support. However, after 8 months exposure the buffering effect disappeared. Moreover, greater crowding had become directly associated with lower support, which in turn was associated with greater increases in psychological distress. All analyses controlled for prior distress. Under some types of chronic stress, the buffering effects of social support may be short-lived because the stressor eventually erodes social support.

Adaptation, Psychological↗
PubMed1991

Traffic congestion, perceived control, and psychophysiological stress among urban bus drivers.

The operation of public transit vehicles in urban centers is a highly stressful job. There has been, however, little detailed analysis of what specific characteristics of the psychosocial or physical job environmental of public transit operators contribute to the high levels of job stress associated with this occupation. In the present study, we show a high degree of association between exposure to peak traffic conditions and on-the-job elevations of urinary catecholamines. These significant relations remain after incorporating various controls for possible selection factors (e.g., job seniority) and health-relevant parameters (e.g., age, smoking). Furthermore, we show that reductions in perceived control on the job partially account for the linkages between traffic congestion and psychophysiological stress.

Adult↗
PubMed1991

Relationship of hospitalized stroke rate and in-hospital mortality to the decline in US stroke mortality.

Data from the National Hospital Discharge Survey was used to estimate the admission rate and in-hospital mortality for US stroke patients from 1970 to 1987. Over this period the hospital admission rate increased from 5.0 per 1,000 population to 5.5 per 1,000, while the in-hospital mortality fell from 18.6 to 10.0% of discharges. When patients experiencing general or late effects or transient ischemic attacks were excluded, the hospital admission rate increased from 2.8 to 4.8 per 1,000 and in-hospital mortality fell from 26 to 12% of discharges. Admission rates increased from 1970 to 1987 for both hemorrhagic strokes and cerebral infarctions, but fell for ill-defined cerebrovascular events, presumably reflecting increased use of computed tomography and magnetic resonance imaging during this period. Mortality for hemorrhagic strokes decreased from 45 to 30% of discharges, mortality for infarctions decreased from 24 to 13% and mortality for ill-defined events fell from 24 to 17%. There are several limitations with the use of the National Hospital Discharge Survey data to estimate changes in hospital admission rates and in-hospital mortality. However, these data suggest a greater role for decreasing case fatality in explaining nationwide declines in stroke mortality rates than has generally been acknowledged.

Acute Disease↗
PubMed1991

Cerebral infarction verified by cranial computed tomography and prognosis for survival following transient ischemic attack.

Of 564 consecutive patients with transient ischemic attack, 350 (62%) had cranial computed tomography performed. Except for date of admission and smoking history, there were few differences between the patients evaluated with computed tomography and the 214 who were not. Cerebral infarcts were found in 59 (17%) of the 350 tomographic evaluations. Previous clinically diagnosed stroke, older age, and male sex were all significantly associated with the occurrence of tomographically verified infarcts (p less than 0.05). After controlling for stroke history and other important covariates, patients with tomographically verified infarcts had significantly shorter survival times than did patients without evidence of infarction on computed tomography (p = 0.035). Thus, cranial computed tomography findings appear to have important prognostic value for estimating survival following transient ischemic attack.

Cerebral Angiography↗
PubMed1991

Reevaluation of transient ischemic attacks as a risk factor for early mortality.

The prevailing belief that transient ischemic attack is a risk factor for cardiovascular morbidity and mortality is based primarily on comparisons of survival of patients after transient ischemic attacks to that of an age-, race-, and sex-adjusted general population. Concomitant conditions that carry a high risk of premature mortality or morbidity, such as ischemic heart disease, hypertension, and diabetes, are very prevalent among patients with transient ischemic attacks. Hence, the poor prognosis of such patients may be attributable to these factors rather than their transient ischemic attack per se, which may only serve to bring patients into the medical system. We compared the survival of 336 patients after transient ischemic attack to that of a control group with a similar risk factor profile consisting of 6,710 patients evaluated for cardiac catheterization. Survival estimates, both unadjusted and adjusted for risk factors, did not differ between the two groups. Three-year survival estimates, after adjustment to the mean value of covariates, were 94% for the patients with transient ischemic attacks and 91% for the controls. These results suggest that the transient ischemic attack may not be an independent risk factor for mortality, although it may identify patients already at increased risk from coexisting conditions.

Cardiac Catheterization↗
PubMed1991

Social hassles and psychological health in the context of chronic crowding.

Data are presented on the interactive effects of an enduring environmental stressor with acute, daily social stressors on psychological distress. A cross-sectional study of males in urban India and a longitudinal study of male and female American college students examined the interplay of these two types of stressors. In India, social hassles in the home predicted psychological symptoms only among residents of crowded homes, after statistically adjusting for income. In America, the interaction between social hassles and crowding was replicated in analyses adjusting for prior psychological symptoms, prior social acquaintanceship with housemates, and income. A six-month follow-up study with the American sample replicated the interaction. In all three analyses of the social hassle-crowding interaction, there was a main effect of crowding but no main effect of social hassles on psychological symptoms. These findings suggest that some chronic environmental stressors may increase the impact of acute social stressors, and highlight the importance of examining contextual factors in the stress and health process.

Adult↗
PubMed1990

Characteristics of stroke victims associated with early cardiovascular mortality in their children.

We assessed the relationship between characteristics of stroke victims and the risk of early death from coronary or cerebrovascular disease (CCVD) among their children. For each of 55 stroke patients selected from a registry which enrolled patients between 1969 and 1973, an index of their progeny's survival was calculated using the age in 1987 of 197 surviving children, and the age at and cause of death for 55 deceased children. Increased risk of CCVD death within families was significantly related to parental age at the time of first stroke, and with the parental history of diabetes mellitus. No significant relationship was found between the children's risk of CCVD death and the stroke patient/parent's sex, race, history of hypertension or cardiac disease, stroke diagnosis (infarction vs hemorrhage), or severity upon admission. These results suggest that family histories of cerebrovascular disease may impart differential risks, depending upon a family history of diabetes, and perhaps, the ages at which ancestral strokes first occurred.

Adolescent↗
PubMed1990

The Peterborough lorry explosion, 22 March 1989: an analysis of the hospital response.

As a result of the lorry explosion on the Fengate Industrial Estate, Peterborough on 22nd March 1989, 82 casualties arrived at Peterborough District Hospital. Despite the fact that casualties arrived at the A&E Department in large numbers before the Major Accident Plan could be implemented, all of the casualties had been assessed and either admitted or sent home within 3 h of the explosion. In the process several valuable lessons were learned, and their implications are discussed in this paper.

Disaster Planning↗
PubMed1990

Weight changes in women with metastatic breast cancer treated with megestrol acetate: a comparison of standard versus high-dose therapy.

One hundred seventy-two patients with advanced breast cancer were randomized to receive 160 or 800 mg megestrol acetate per day. Patients were monitored monthly for weight, blood pressure, performance status, edema, measurement of clinically evident lesions, and toxicities. Pretreatment characteristics were similar in both arms. Weight gain was the most commonly seen side effect, with 52% of patients gaining in excess of 10 lb and 28% gaining more than 20 lb. Median weight gain for standard-dose treatment was 5 lb compared with 18 lb for high-dose treatment. There was no dose modification for excessive weight gain in any of the patients receiving the standard dose but doses were modified in 15% of those receiving high-dose megestrol acetate. Weight gains for both groups were analyzed at 30, 90, and 180 days after study entry. Treatment arm, age, prior therapy, response to prior endocrine therapy, race, performance status, dominant disease site, and number of disease sites were included in the analysis. At 30 days, patients taking high-dose megestrol acetate had a mean weight gain of 2.5 lb whereas patients taking the standard dose had stable weights. Factors predictive of weight gain were younger age (P = .0012) and fewer disease sites (P = .017). At 90 and 180 days, patients taking high-dose megestrol acetate had consistently gained more weight than those taking the standard dose (9.0 and 16.0 lb v 2.5 and 9.0 lb, respectively). Significant covariables were treatment arm (P = .0006) and younger age (P = .0211). Probability of gaining 20 lb was dependent only on treatment dose (P = .0002), and median time to a 20-lb weight gain was 217 days. Increases in systolic and diastolic blood pressures were seen in both groups, but the differences were not significant. Megestrol acetate is associated with weight gain in women with advanced breast cancer, and the amount of weight gained correlates directly with dose of megestrol acetate, length of treatment, and age of patient.

Blood Pressure↗
PubMed1990

The effect of chromium picolinate on serum cholesterol and apolipoprotein fractions in human subjects.

Chromium has been implicated as a cofactor in the maintenance of normal lipid and carbohydrate metabolism. A deficiency of chromium results from diets low in biologically available chromium. Picolinic acid, a metabolite of tryptophan, forms stable complexes with transitional metal ions, which results in an improved bioavailability of the metal ion chromium. To determine whether or not chromium picolinate is effective in humans, 28 volunteer subjects were given either chromium tripicolinate (3.8 micromol [200 micrograms] chromium) or a placebo daily for 42 days in a double-blind crossover study. A 14-day period off capsules was used between treatments. Levels of total cholesterol, low-density lipoprotein (LDL) cholesterol, and apolipoprotein B, the principal protein of the LDL fraction, decreased significantly while the subjects were ingesting chromium picolinate. The concentration of apolipoprotein A-I, the principal protein of the high-density lipoprotein (HDL) fraction, increased substantially during treatment with chromium picolinate. The HDL-cholesterol level was elevated slightly but not significantly during ingestion of chromium picolinate. Only apolipoprotein B, of the variables measured, was altered significantly during supplementation with the placebo. These observations show that chromium picolinate is efficacious in lowering blood lipids in humans.

Adult↗
PubMed1989

Cerebral infarction in patients with transient ischemic attacks.

Cranial computed tomography of 284 patients with transient ischemic attacks (TIAs) and without previous stroke was evaluated. The sample population included patients with carotid and/or vertebrobasilar TIAs. Computed tomography revealed cerebral infarction in 34 patients, including 5 with multiple infarctions. The lesion location was consistent with TIA symptoms in 16 patients. In another 16 patients, however, the lesion location did not correspond to the TIA symptoms; these lesions were attributed to previous silent infarctions. Two patients with multiple infarctions had both symptomatic and asymptomatic lesions. Age and carotid stenosis were each significantly related to an increased chance of detecting cerebral infarction (either symptomatic or asymptomatic). No significant relationship between race, gender, hypertension, diabetes, cardiac disease, or smoking and the incidence of infarction was found by either univariate or multivariate analyses.

Aged↗