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J M Stevenson

Publications and source records attributed to J M Stevenson.

At least 37 records · Page 2Linked to original sources
PubMed1994

High-performance liquid chromatography and photoaffinity crosslinking to explore the binding environment of nevirapine to reverse transcriptase of human immunodeficiency virus.

Nevirapine (BI-RG-587) is a potent inhibitor of the polymerase activity of reverse transcriptase of human immunodeficiency virus type-1. Nevirapine, as well as several other non-nucleoside compounds of various structural classes, bind strongly at a site which includes tyrosines 181 and 188 of the p66 subunit of reverse transcriptase. The chromatography which was utilized to explore this binding site is described. BI-RH-448 and BI-RJ-70, two tritiated photoaffinity azido analogues of nevirapine, are each crosslinked to reverse transcriptase. The use of several HPLC-based techniques employing different modes of detection makes it possible to demonstrate a dramatic difference between the two azido analogues in crosslinking behavior. In particular, by comparing HPLC tryptic peptide maps of the photoadducts formed between reverse transcriptase and each azido analogue, it can be shown that crosslinking with BI-RJ-70 but not with BI-RH-448 is more localized, stable, and hence exploitable for the identification of the specifically bonded amino acid residue(s). In addition, comparison of the tryptic maps also makes it feasible to assess which rings of the nevirapine structure are proximal or distal to amino acid side chains of reverse transcriptase. Finally, another feature of the HPLC peptide maps is the application of on-line detection by second order derivative UV absorbance spectroscopy to identify the crosslinked amino acid residue.

Affinity Labels↗
PubMed1994

The use of the Nordic questionnaire in an industrial setting: a case study.

The aims of this study were to identify: (1) whether patterns of reported injury are differentially affected by the structure of the interview and qualifications of the interviewer; and (2) whether the Nordic Questionnaire is sensitive enough to identify different patterns of reported injuries across two different workstations. To accomplish this the Standardized Nordic Questionnaire was administered by both a physiotherapist and an ergonomist to two similar but separate workstations of a manufacturing plant. Analysis of the injury-reporting frequencies produced results indicating increased reporting to the ergonomist in two of five upper limb and trunk body regions considered at one workstation and in one region at the other. Differences in reporting frequencies between workstations were also found. Physical demands analyses performed in each area confirmed that differing job requirements existed in the two workstations under consideration. Early identification of potential job-specific injuries by an in-house ergonomist can initiate appropriate intervention strategies prior to the onset of chronic injuries.

Journal Article↗
PubMed1994

Development of physical fitness standards for Canadian Armed Forces older personnel.

The purpose of the study was to develop a minimum physical fitness standard for Canadian Forces personnel, 35 years and older, based on common criteria for physically demanding tasks. A random sample of 100 men and 76 women performed the Exercise Prescription (EXPRES) test and five physically demanding tasks that simulate common military tasks, while restricted, for safety reasons, to 90% maximal predicted heart rate. Results indicated poor predictive power, as variances ranged from 5 to 55% between EXPRES fitness scores and task performance. With approval from an expert panel, the 75th percentile score for each task was selected as the cutting criterion. The passing-group data were converted to Z-scores in order to determine the 5th percentile from each EXPRES item: these scores became the EXPRES fitness standard. The minimum fitness standard had a greater impact on women than on men but was representative of the passing groups for both sexes.

Adult↗
PubMed1993

Methods for analysing county-level mortality rates.

The identification of counties burdened by exceptionally high rates of mortality is a fundamental step in the development of state-based intervention and prevention strategies. However, the estimation of rates from small geographic areas presents special problems, especially for rare events. This paper compares the use of crude and age-standardized rates to the use of Poisson regression models and empirical Bayes models for analysing county-level mortality rates. The results demonstrate both practical and heuristic advantages of the empirical Bayes models. Age-standardized rates adjust for differences in age structure among countries but are vulnerable to extreme variability in county age-specific rates. In our example--an analysis of diabetes mortality rates--Poisson regression did not improve the variability of estimated county-level rates. Adjusted empirical Bayes estimates dramatically shrink the observed rates while preserving some separation of the counties with extreme rates. Also, empirical Bayes estimates of rates for countries with no observed deaths are shrunk close to the prior mean.

Adolescent↗
PubMed1993

Risk factors for coronary heart disease mortality among persons with diabetes.

Although coronary heart disease is a leading cause of morbidity and mortality among persons with diabetes, the risk factors for coronary heart disease have not been well established for this population. The authors performed a case-control analysis by using data from two large population-based surveys. Cases of persons who died of coronary heart disease were identified from the 1986 National Mortality Followback Survey, and controls were taken from behavioral risk factor surveys conducted in 35 states in 1988. Diabetic women younger than 55 years with no other risk factors for coronary heart disease had a 16-fold higher risk of dying from coronary heart disease than did women without diabetes. About one-third of younger women who died of coronary heart disease had diabetes. Diabetic men less than 45 years old with no other risk factors for coronary heart disease had an eightfold higher risk of coronary heart disease mortality. Among older white men and women, diabetes increased the risk of mortality from coronary heart disease about twofold. In younger diabetics, current cigarette smoking was associated with a 50% increase in risk, and high blood pressure increased the risk more than threefold. In the older age group, risk factors for coronary heart disease mortality were similar among those with and those without diabetes: Cigarette smoking and high blood pressure each were associated with about a twofold increase in risk. Diabetes is a particularly strong risk factor for mortality from coronary heart disease in young adults. Smoking and blood pressure control represent major opportunities to reduce the risk of coronary heart disease among persons with diabetes.

Adult↗
PubMed1992

Frequency of recording of diabetes on U.S. death certificates: analysis of the 1986 National Mortality Followback Survey.

We used data from the 1986 National Mortality Followback Survey to estimate the frequency of recording of diabetes on death certificates and to determine factors associated with recording of diabetes among decedents aged 25 years and older who died in the U.S. in 1986. Among 2766 decedents for whom a history of diabetes was provided by a personal informant, diabetes was recorded on an estimated 38.2% of death certificates and was listed as the underlying cause of death on an estimated 9.6%. The frequency of recording of diabetes was strongly related to age and duration of diabetes--among those aged 25-44 years who had had diabetes for 15 or more years, the frequency of recording was 71.9%. When other listed causes of death included conditions that may have been related to diabetes, such as cardiovascular disease, diabetes was recorded between 45 and 70% of the time, depending on the other causes. Diabetes is usually not recorded on death certificates, and the likelihood of recording is related to decedent characteristics, particularly age, duration of diabetes, and co-morbidity.

Adult↗
PubMed1992

Stages 1 and 2 epidermoid carcinoma of the glottic larynx: involvement of the anterior commissure.

Data on 55 patients with stages 1 and 2 epidermoid carcinoma of the glottic larynx treated from 1978 to 1988 were retrospectively reviewed. Twenty-six patients had involvement of the anterior commissure (AC). Local and ultimate local control rates achieved, respectively, with mean follow-up of 41 months (range, 6-120 months), were as follows: 92% and 100% for patients without AC involvement and stage T1a lesions, 60% and 80% for patients without AC involvement and stage T2 lesions, 100% and 100% for patients with AC involvement and stage T1a lesions, 100% and 100% for patients with AC involvement and stage T1b lesions, and 75% and 100% for patients with AC involvement and stage T2 lesions. There was no correlation between the degree of response at completion of treatment and local control. There was no difference in the local control rate of patients with and without involvement of the AC. Factors associated with a decreased local control rate include extensive subglottic extension and use of a single lateral field technique. Surgical salvage after failure of radiation therapy is effective and can be performed with acceptable morbidity.

Carcinoma, Squamous Cell↗
PubMed1992

Trends in diabetes and diabetic complications, 1980-1987.

OBJECTIVE: Although diabetes is a major source of morbidity and mortality in the United States, only recently has a unified national surveillance system begun to monitor trends in diabetes and diabetic complications. RESEARCH DESIGN AND METHODS: We established a diabetes surveillance system using data for 1980-1987 from vital records, the National Health Interview Survey, the National Hospital Discharge Survey, and the Health Care Financing Administration's records to examine trends in the prevalence and incidence of diabetes, diabetes mortality, hospitalizations, and diabetic complications. RESULTS: From 1980 through 1987, the number of individuals known to have diabetes increased by 1 million--to 6.82 million. Age-standardized prevalence for diabetes increased 9% during this period, from 25.4 to 27.6/1000 U.S. residents (P = 0.03). The incidence of diabetes increased among women (P = 0.003), particularly among those greater than 65 yr old (P = 0.02). Age-standardized mortality rates (for diabetes as either an underlying or contributing cause) per 100,000 individuals with diabetes declined 12%, from 2350 to 2066. Annual mortality rates from stroke (as an underlying cause and diabetes as a contributing cause) and diabetic ketoacidosis declined 29% (P = 0.003) and 22% (P less than 0.001), respectively. During these 8 yr, hospitalization rates for major CVD and stroke (as the primary diagnoses and diabetes as a secondary diagnosis) increased 34% (P = 0.006) and 38% (P = 0.01), respectively. Also during this period, hospitalization rates increased 21% for diabetic ketoacidosis (P = 0.01) and 29% for lower-extremity amputations (P = 0.06). From 1982 through 1986, treatment for end-stage renal disease related to diabetes increased greater than 10% each year (P less than 0.001). The prevalence of diagnosed diabetes was nearly twice as high in blacks as in whites (P = 0.04). Blacks also had increased rates of lower-extremity amputation (P = 0.02), diabetic ketoacidosis (P less than 0.001), and end-stage renal disease (P = 0.01). CONCLUSIONS: Diabetes surveillance data will be useful in planning, targeting, and evaluating public health efforts designed to prevent and control diabetes and its complications.

Amputation, Surgical↗
PubMed1992

Seasonal variation in venison quality of mature, farmed red deer stags in New Zealand.

Two studies involving 20 red deer (Cervus elaphus) stags were conducted to determine the effects of season on venison quality. In each study, five sexually mature red deer stags were slaughtered immediately preceding the rut (autumn) and five were slaughtered after the rut. Stags slaughtered postrut had lower carcass weights (25 to 30%) than those slaughtered prerut. Average bodywall thickness measurements above the 12th rib (an indicator of fat thickness) were approximately 31 mm prerut compared with 3 to 7 mm postrut. Individual muscles and retail cuts (which included subcutaneous and intermuscular fat) were heavier in prerut carcasses. There were significant decreases in intramuscular fat in both the longissimus muscle and the semimembranosus muscle. Postrut longissimus muscle steaks appeared brighter and(or) fresher than the other groups; color acceptability was negatively correlated (P less than .05) with fat content. Prerut streaks from both muscles were more tender than postrut steaks from those muscles. Overall desirability and tenderness were highly correlated (r = .94 and .82 for longissimus muscle and semimembranosus muscle, respectively).

Animals↗
PubMed1992

Development of physical fitness standards for Canadian Armed Forces younger personnel.

The purpose of this study was to develop minimum physical fitness standards based on common task criteria for personnel younger than 35 years of age in the Canadian Armed Forces. A random sample of 66 men and 144 women performed the Exercise Prescription (EXPRES) test and five physically demanding tasks that simulated common military tasks. Common cutting scores were selected as the point at which 75% of the total weighted sample passed each task. Since there were significant differences between the sexes in task performance and technique execution, the groups were analyzed separately. Results indicated a range in variance of 14 to 48% between military task performance and physical fitness test score, thus suggesting that fitness measures are a poor predictor of task performance. Because of the low variance observed the passing group of each task was treated as a representative sample of subjects whose fitness profiles were indicative of those able to meet task criteria. The 5th percentile fitness scores of the passing group were proposed as the minimum fitness standard. These conditions resulted in fitness standards that were physically more demanding for women than for men.

Adult↗
PubMed1991

A family study of Gilles de la Tourette syndrome.

Previous studies have demonstrated that Gilles de la Tourette syndrome (TS) is a familial disorder and that chronic tics (CT) and obsessive compulsive disorder (OCD) appear to be etiologically related to the syndrome. In the present study we report the results from a study of 338 biological relatives of 86 TS probands, 21 biologically unrelated relatives of adopted TS probands, and 22 relatives of normal subjects. The 43 first-degree relatives of the adopted TS and normal probands constituted a control sample. The rates of TS, CT, and OCD in the total sample of biological relatives of TS probands were significantly greater than in the relatives of controls. In addition, the morbid risks of TS, OCD, and CT were not significantly different in families of probands with OCD when compared to relatives of probands without OCD. These findings provide further evidence that OCD is etiologically related to TS.

Humans↗
PubMed1991

Stairclimbing kinematics on stairs of differing dimensions.

The purpose of this study was to provide a kinematic description of the task of stair ascent and descent. Fifteen women were divided into short, medium, and tall subject groups. Three testing staircases of different riser and tread dimensions were used. Temporal and cinematographic data were collected simultaneously via switchmats and a high-speed camera, respectively. Measures of stairclimbing gait cycle duration, swing and stance phase durations, cadence, and velocity appeared to be systematically related to subject height. Stance (19% to 64%) and swing (36% to 81%) phase durations varied considerably depending on stair dimensions during stair descent. Less variation was observed in stance (50% to 60%) and swing (40% to 50%) values during tasks of stair ascent. Individuals appeared to adjust to stair dimensions by varying the flexion/extension patterns of the knee rather than those of the ankle or hip. Depending on the staircase climbed, knee flexion angles ranging from 83 degrees to 105 degrees were required. Stair dimensions, therefore, appeared to influence the temporal and angular kinematics of the lower limb during stairclimbing.

Adult↗
PubMed1990

Single camera photogrammetric technique for restricted 3D motion analysis.

The purpose of this study was to use a single camera to determine the true elbow flexion angle with the arm plane oriented arbitrarily with respect to the camera. A mathematical theory was developed and a mechanical arm model was constructed to validate the theory. A static weightlifting skill was analysed to investigate the viability of the technique on the human subject. The validation of the theory showed the error associated with the elbow flexion angle was reduced from as high as 108 degrees when uncorrected to within 3 degrees when corrected by the technique. The elbow flexion angle of the human arm can be calculated to within 6 degrees of error for static weightlifting skill analysis.

Algorithms↗
PubMed1989

The relationship between eggshell porosity and air space gas tensions measured before and during the parafoetal period and their effects on the hatching process in the domestic fowl.

The partial pressure of gases in the air space were measured before and during the parafoetal period for domestic fowl eggs of the same initial weight but varying in eggshell conductance. Embryos developed and hatched normally from eggs with a wide range of shell conductance and resultant air space gas partial pressures. Air space PO2 levels measured just before pipping ranged from 55 to 65 mm Hg in low and high conductance eggs, respectively, whilst PCO2 levels ranged from 75 to 55 mm Hg. With increasing shell conductance embryos membrane-penetrated and pipped the shell later, but hatch time was unaffected. Membrane penetration and external pipping appeared to occur in response to the partial pressures of gas in the air space but not in response to one particular level of air space PO2 or PCO2. During the parafoetal stage air space PO2 decreased at about 3.8 mm Hg/h and air space PCO2 increased at about 1.8 mm Hg/h and these rates of change were unaffected by eggshell conductance.

Animals↗
PubMed1989

Isoinertial tests to predict lifting performance.

Previous research has found isoinertial strength testing to be superior to isometric and isokinetic strength testing for prediction of task performance. The purpose of this study was to investigate tests on an isoinertial lifting machine (ILM) and their ability to predict performance on actual lifting tasks. Sixteen male subjects performed two lifting tasks: maximum box lift to truck-bed height of 1.35 m; and 'speed lifts' of 60 concrete blocks (each 22.7 kg) to the same height. These performance tests were compared to three ILM tests: a maximal lift to 1.83 m, a second maximal lift to 1.52 m, and an endurance test that entailed 60 timed ILM lifts of 22.7 kg to 1.83 m. Pearson product-moment correlations between ILM tests and performance tasks varied from r = 0.55 to 0.71. Therefore, the isoinertial test protocols employed in this study were able to account for only 30% to 50% of the variance in the performance of maximal lifting and endurance tasks. In was concluded that prediction of maximal lifting ability or endurance ability using an ILM might be enhanced by closer approximation of specific task variables, or by inclusion of dynamic parameters to measure technique.

Adult↗
PubMed1989

An examination of social typologies in autism.

A system proposed by Wing and coworkers for subtyping autistic individuals on the basis of social interaction is examined in 78 autistic, 39 atypical, and 32 nonautistic, developmentally disordered individuals. Clinical ratings and questionnaire data based on the proposed subtypology were employed. Clinicians were able to reliably group both autistic and nonautistic cases into the three subtypes; these subtypes were strongly related to IQ. Issues relating to the validity and utility of this subtypology are discussed.

Adolescent↗
PubMed1989

Method for determining vertebral body positions in the sagittal plane using skin markers.

A method by which the location of vertebral bodies can be estimated from the external profile of the spine in the sagittal plane is described. The technique involves a normalization of the curve from T1 to L5 and approximation using a cubic spline. Mapping functions are developed that enable the transformation of a skin profile to a vertebral centroid curve. Data were obtained for 13 subjects between the ages of 13 and 17 who had undergone lateral spinal radiographs with radiopaque skin markers over the vertebral spinal processes. Results suggested that vertebral body centroids could be estimated from the skin profile to a precision having a standard error of the estimate of 0.4 cm. This was improved to 0.2 cm if the lumbar curve were considered separately.

Humans↗