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H L Taylor

Publications and source records attributed to H L Taylor.

At least 19 recordsLinked to original sources
PubMed2005

Interlaboratory comparison of red-cell ATP, 2,3-diphosphoglycerate and haemolysis measurements.

BACKGROUND AND OBJECTIVES: Red blood cell (RBC) storage systems are licensed based on their ability to prevent haemolysis and maintain RBC 24-h in vivo recovery. Preclinical testing includes measurement of RBC ATP as a surrogate for recovery, 2,3-diphosphoglycerate (DPG) as a surrogate for oxygen affinity, and free haemoglobin, which is indicative of red cell lysis. The reproducibility of RBC ATP, DPG and haemolysis measurements between centres was investigated. MATERIALS AND METHODS: Five, 4-day-old leucoreduced AS-1 RBC units were pooled, aliquotted and shipped on ice to 14 laboratories in the USA and European Union (EU). Each laboratory was to sample the bag twice on day 7 and measure RBC ATP, DPG, haemoglobin and haemolysis levels in triplicate on each sample. The variability of results was assessed by using coefficients of variation (CV) and analysis of variance. RESULTS: Measurements were highly reproducible at the individual sites. Between sites, the CV was 16% for ATP, 35% for DPG, 2% for total haemoglobin and 54% for haemolysis. For ATP and total haemoglobin, 94 and 80% of the variance in measurements was contributed by differences between sites, and more than 80% of the variance for DPG and haemolysis measurements came from markedly discordant results from three sites and one site, respectively. In descending order, mathematical errors, unvalidated analytical methods, a lack of shared standards and fluid handling errors contributed to the variability in measurements from different sites. CONCLUSIONS: While the methods used by laboratories engaged in RBC storage system clinical trials demonstrated good precision, differences in results between laboratories may hinder comparative analysis. Efforts to improve performance should focus on developing robust methods, especially for measuring RBC ATP.

2,3-Diphosphoglycerate↗
PubMed1993

Quasi-transfer as a predictor of transfer from simulator to airplane.

Simulators have emerged as important components of flight-training programs. Nevertheless, the development of design principles that can maximize training transfer and cost-benefit trade-offs are not well established. The most significant challenge to research that would bear on simulator design principles is the difficulty and expense of flight transfer experiments. This difficulty and expense can be reduced by the use of an insimulator transfer design, designated here as a quasi-transfer study, in which transfer is to a high-fidelity configuration of a simulator. Of primary concern for such studies is whether the implied assumption of correspondence between quasi-transfer and transfer effects is well founded. In this article, we review evidence that bears on this issue. The evidence is not entirely supportive but does indicate some correspondence between quasi-transfer and transfer.

Aircraft↗
PubMed1993

The effects of wearing protective chemical warfare combat clothing on human performance.

U.S. Department of Defense studies to measure performance decrements associated with wearing chemical warfare (CW) protective combat clothing indicate that heat stress seriously degrades human performance. Even when heat stress is not a significant factor, performance of many combat, combat support, and combat service support tasks is degraded. In most field studies, many crews of combat units became operationally ineffective due to voluntary withdrawal of individual crewmembers. Many combined arms, field studies, and laboratory studies indicate that when CW-protective combat clothing is worn performance is seriously degraded for the detection of targets, engagement time, accuracy of fire, and manual dexterity tasks; and that a variety of psychological effects are created. Further, the degree of performance degradation varied with the tasks performed. Training in CW-protective combat clothing permits learning to modify procedures and consequently reduce negative effects, provided heat stress is not a significant factor. A growing body of evidence indicates there is inadequate training in the use of CW-protective combat clothing. A critical need exists for more and better training of skills needed under CW-conditions.

Chemical Warfare↗
PubMed1989

HIV infection in England and Wales: a changing pattern.

Of 32,983 specimens from 307 sources in England and Wales tested in the Virus Reference Laboratory for anti-HIV between 1984 and 1987, 6491 (20%) were positive. Ninety-five per cent of the positive subjects were male and 44% of them were from three London genito-urinary medicine clinics. In 1987 the numbers of newly diagnosed HIV infections decreased in homosexual men and haemophiliacs and increased in injecting drug abusers; 148/1199 (12%) of all the positive findings in 1987 were in females. Between 1984 and 1987 the proportion of anti-HIV positive individuals who were asymptomatic fell by nearly 10% and the proportion with AIDS/ARC rose by nearly 10%. Of the requests leading to positive results 1280 (20%) were recognized as duplicates of previous positive results, while for 34% of the requests no clinical information was provided. These deficiencies in the data compromise HIV surveillance based on diagnostic testing, and supplementary bias-free data are needed.

Adolescent↗
PubMed1989

Leukaemia and residence near electricity transmission equipment: a case-control study.

A population-based case-control study of leukaemia and residential proximity to electricity supply equipment has been carried out in south-east England. A total of 771 leukaemias was studied, matched for age, sex, year of diagnosis and district of residence to 1,432 controls registered with a solid tumour excluding lymphoma; 231 general population controls aged 18 and over from one part of the study area were also used. The potential for residential exposure to power frequency magnetic fields from power-lines and transformer substations was assessed indirectly from the distance, type and loading of the equipment near each subject's residence. Only 0.6% of subjects lived within 100 m of an overhead power-line, and the risk of leukaemia relative to cancer controls for residence within 100 m was 1.45 (95% confidence interval (CI) 0.54-3.88); within 50 m the relative risk was 2.0 but with a wider confidence interval (95% CI 0.4-9.0). Over 40% of subjects lived within 100 m of a substation, for which the relative risk of leukaemia was 0.99. Residence within 25 m carried a risk of 1.3 (95% CI 0.8-2.0). Weighted exposure indices incorporating measures of the current load carried by the substations did not materially alter these risks estimates. For persons aged less than 18 the relative risk of leukaemia from residence within 50 m of a substation was higher than in adults (PR = 1.5, 95% CI 0.7-3.4).

Electromagnetic Fields↗
PubMed1988

Instrument flight performance under the influence of certain combinations of antiemetic drugs.

Two different combinations of antiemetic drugs were evaluated using a digital flight simulator. Drug treatments consisted of a lactose placebo, a combination of thiethylperazine (10 mg) and cimetidine (300 mg), and a combination which added promethazine (25 mg) to the two-drug combination. The performance effects of these combinations were evaluated on both a dual task (instrument flight task with the Sternberg Memory Scanning task) and a single task condition (Sternberg task only) for 3 h post drug ingestion. Analysis indicated a significant treatment effect on three of the six flight performance variables and that the three-drug combination, containing promethazine, was primarily responsible for the decrease in performance. Implications for operation in a radiation environment are that thiethylperazine and cimetidine will not cause significant performance decrements, but the addition of promethazine to those two drugs will significantly impair performance. The Sternberg task was sensitive to changes in workload.

Adult↗
PubMed1987

Atropine sulfate effects on aviator performance and on respiratory-heart period interactions.

In this study, 20 human volunteers received a placebo and atropine doses of 0.5, 1.0, 2.0, and 4.0 mg X 75 kg-1 in a Latin Square double blind design, and effects were monitored for 3 h postinjection. The 2.0 mg and the 4.0 mg doses resulted in significant flight simulator performance decrements beginning at 1 h postinjection with only minimal recovery by 3 h postinjection. Electrocardiogram data were used to estimate the amplitude of respiratory sinus arrhythmia (RSA) which was more sensitive than mean heart period or mean heart period variance to the effects of atropine. These parasympathetic effects were relatively rapid in onset and peaked within the first 40-min period for the 2.0 and 4.0 mg doses. The onset of performance effects were delayed 1 h 40 min for the 2.0 mg and 1 h 00 min for the 4.0 mg treatment.

Adult↗
PubMed1986

Comparison of the effects of atropine sulfate and ethanol on performance.

The flight simulator performance decrements resulting from atropine injections were compared to similar decrements resulting from ethanol toxicosis. There were 20 volunteers that received 0.0, 0.5, 1.0, 2.0, and 4.0 X 75 kg-1 of atropine sulfate under double-blind conditions. The performance decrements at each atropine sulfate treatment level for each subject were determined by computing root mean square (RMS) deviations for five flight performance variables. The data set from a previous study concerned with the effects of ethanol on pilot performance was reanalyzed, and the decrements for the five variables at the 0.082% blood alcohol level (BAL) were computed. Probit analysis was used to estimate the effective dose (ED50) at which 50% of the subjects in the atropine sulfate experiment were expected to display decrements in excess of those observed for the 0.082% BAL. The ED50 was 3.12 mg of atropine sulfate.

Adult↗
PubMed1985

Leisure time physical activity and its relationship to coronary risk factors in a population-based sample. The Minnesota Heart Survey.

Energy expenditure in leisure time physical activity was measured using the Minnesota Leisure Time Physical Activity Questionnaire in a probability sample of 25- to 74-year-old residents of the seven-county metropolitan area of Minneapolis-St. Paul, Minnesota. Geometric mean estimates of leisure time physical energy expenditure were 193 kcal per day for men and 111 kcal per day for women. Only 34% of men and 17% of women expended 2,000 kcal or more per week in leisure time physical activity. Energy expenditure, especially in heavy intensity activities, declined with age, more so for women than men. Significant associations were observed between leisure time physical activity, particularly heavy intensity activity, and other coronary heart disease risk factors. Greater heavy intensity activity was associated with higher education (r = 0.14 to 0.26), greater Type A behavior (r = 0.14 to 0.15), higher serum high density lipoprotein (HDL) cholesterol levels (r = 0.09 to 0.10), lower serum thiocyanate (r = 0.10 to -0.14), lower body mass index (r = -0.10 to -0.11), lower heart rate (r = -0.07 to -0.10), and lower systolic blood pressure (r = -0.06 to -0.09). Thus, although energy expenditure was generally low in this population, greater leisure time physical activity for the most part was associated with lower coronary risk factors.

Adult↗
PubMed1985

Measuring the effects of neurotoxicants on flight simulator performance.

The Aviation Research Laboratory has developed a methodology for evaluating toxicant effects on pilot performance. Flight data are collected using a digital flight simulator, the ILLIMAC (ILLInois Micro Aviation Computer), during holding patterns and instrument landing system approaches. The flight data are recorded by a separate microcomputer, which also presents the Sternberg memory searching task. A preliminary study examined pilot performance in the simulator and cholinesterase inhibition by insecticides in agricultural pilots. The correlation between the physiological parameters and the pilot performance data was determined. Experiments are planned to determine the effects of a variety of drugs on pilot performance. Neurotoxicants to be studied include ethanol, three antiemetic drugs, and atropine sulfate.

Accidents, Aviation↗
PubMed1984

The effect of "usual care" on cardiovascular risk factors in a clinical trial.

The use of referral to "usual care" (UC) for participants in randomized clinical trials satisfies the need for a control group who receive medical attention at the level of community standards. However, it has been suggested that this method, which may include follow-up with multiple examinations to collect trial information, may actually enhance quality of care. To determine the effect of this UC status, 64 UC men from the Multiple Risk Factor Intervention Trial (MRFIT) were matched on serum cholesterol (SC), diastolic blood pressure (DBP), and age with men who had similar characteristics at the initial recruitment screening but were not selected for the trial. Both groups were remeasured an average of 45 months after the initial recruitment. DBP at the second measurement was lower in both groups (11 mm Hg) and did not differ between groups. The percentage taking blood pressure medications was similar. SC was unchanged in either group. Reduction in risk observed in this MRFIT usual care group appears to be related to improved preventive practice in the community, specifically in blood pressure treatment. The additional effect of participation in a clinical trial as a control subject appears minimal for these risk characteristics.

Adult↗
PubMed1984

Dietary measures of physical activity.

The relationships between cardiovascular fitness, body fatness, and the number of calories required to maintain stable body weight over a baseline period of three weeks were studied in 21 healthy obese males aged 20-44 years who participated in a controlled feeding experiment at the Division of Epidemiology (formerly the Laboratory of Physiological Hygiene) of the School of Public Health, University of Minnesota, in August 1980-June 1981. statistically significant relationships were found between the number of calories actually consumed per kg of body weight (kcal/kg) and body fatness (r = -0.79, p = 0.001), and number of calories consumer per kg of body weight and physical work capacity (VO2 max) (r = 0.76, p = 0.001). Using body fatness quartiles, the caloric intake per kg of body weight and VO2 max decreased progressively as body fatness increased through its four quartiles. These relationships were also seen when reported caloric intake from a three-day food record was used; however, the magnitude was attenuated. On the other hand, caloric intake unadjusted for body weight, whether actual or reported, was unrelated to both body fatness and VO2 max. To determine whether these relationships hold true for less obese subjects, the authors have also analyzed and compared their results with the data from previously reported feeding experiments done at the University of Minnesota. Correlations between body fat indices and actual caloric intake were similar for both studies. Therefore, the authors conclude that in these relatively young, healthy, and sedentary males with a wide range of body fatness and body weight, the observed relationships between caloric intake adjusted for body weight, body fatness and VO2 max reflect habitual physical activity. These data confirm epidemiologic observations of an inverse relationship between caloric intake per kg of body weight and body fatness, and provide a rationale for using caloric intake adjusted for body weight as a measure of long-term habitual physical activity. Thus, these data bolster the interpretation that an inverse relationship between caloric intake per kg of body weight and mortality reflects a positive health effect of long-term physical activity. This index may be particularly useful in large population studies.

Adult↗
PubMed1984

Prevalence of overweight and weight loss behavior in a metropolitan adult population: the Minnesota Heart Survey experience.

Data from two major surveys, conducted in the Minneapolis-St. Paul metropolitan area in 1973-74 and 1980-81, were used to estimate the prevalence of overweight. In 1980-81, weight history and the prevalence of dieting behaviors were also obtained. The prevalence of overweight was greater in the 1980-81 survey than in 1973-74. Increases were observed in all ages in women, but only in the 40-59 year age ranges in men. In 1980-81, dieting to control weight was widely reported by both sexes, even among those who had never been overweight. Of those who reported having been overweight, approximately one-third reported they had successfully reduced. More men than women reported having been overweight, but more women reported having dieted to lose weight. Formal weight reduction programs were used much more by women than men. Although most dieting attempts consisted of balanced, reduced calorie regimens, a significant percentage were "fad" types, whose nutritional safety may be questioned. Overall, contrary to findings based on clinical populations, weight reducing efforts often appear to be successful. Nevertheless, overweight remains a significant public health problem in this community.

Adult↗
PubMed1983

Sudden death and acute myocardial infarction in a metropolitan area, 1970-1980. The Minnesota Heart Survey.

To determine the causes of the nationwide decline in deaths due to coronary heart disease, the Minnesota Heart Survey enumerated coronary deaths among persons 30 to 74 years old in Minneapolis-St. Paul. The survey also ascertained rates of hospitalization and case fatality during hospitalization for acute myocardial infarction. For deaths occurring between 1970 and 1978 that were due to coronary heart disease, the rates outside the hospital declined by 43 per cent in men and 40 per cent in women, and the rates in hospital emergency rooms increased by 311 per cent in men and 200 per cent in women. In both these years about two thirds of all such deaths occurred outside hospital wards. Between 1970 and 1980, hospitalization rates for acute infarction in persons 30 to 74 years old declined 8 per cent among men and 26 per cent among women, and case fatality in the hospital in persons 45 to 74 years old declined 29 per cent in men and 27 per cent in women. These changes are probably due to the combined influence of changes in risk factors in the population and improved care of patients with acute myocardial infarction before and during hospitalization.

Adult↗