Biomedical subjects
Publications and source records attributed to H Davis.
We discuss some of the issues that have arisen during the development and introduction into practice of information materials for health professionals and patients that aim to promote clinical effectiveness and informed patient participation in clinical decision making.
OBJECTIVE: To examine the impact of central adiposity upon hemodynamic functioning at rest and during stress in adolescents. DESIGN: Cross-sectional, correlational study. SUBJECTS: 46 White and 49 Black normotensive adolescents with family histories of essential hypertension. MEASUREMENTS: Systolic and diastolic blood pressure (SBP, DBP), cardiac output and total peripheral resistance responses were assessed at rest, during postural change, video game challenge and forehead cold stimulation. Specific lower and higher waist-to-hip ratio (WHR) tertiles were created for each gender and then integrated for analyses. This resulted in a lower WHR tertile of 11 Whites and 21 Blacks and an upper WHR tertile of 15 Whites and 17 Blacks. RESULTS: No differences in age, gender or ethnicity proportions were found between tertile groups (all P > 0.21). The upper WHR group showed greater body weight, waist and hip circumferences, body mass index (BMI), triceps skinfold and body surface area (all P < 0.001). Controlling for peripheral (that is, triceps skinfold) and overall (that is, BMI) adiposity, the upper WHR group exhibited greater SBP (that is, peak response minus mean pre-stressor level) to all three stressors and greater DBP reactivity to postural change and cold pressor (all P < 0.05). CONCLUSION: Central adiposity appears to adversely influence hemodynamic functioning during adolescence. Underlying mechanisms responsible for these associations require exploration.
The Community Child and Family Service is a primary care and community-based child mental health service working in a socio-economically disadvantaged area of inner London. This paper outlines the strategic framework and value base from which the service has developed. The clinical projects set up by the service in general practice, community and education settings are described, as are the training and supervision programmes that have been undertaken. The framework for evaluating the clinical and economic outcomes of the projects is outlined. There has been a positive response from purchasers, providers and clients to the introduction of this Service. The relationship between community- and hospital-based child mental health services is discussed, as is the future direction of the Service.
To determine predictors of left ventricular mass (LVM) and hypertrophy (LVH), 56 black and 30 white normotensive healthy youths (mean age 12.6 +/- 2.3 years at initial visit) were studied twice, 2.5 years apart. During the initial visit, anthropometric variables and hemodynamics were measured at rest and before, during, and after 4 physical and behavioral stressors. 2-D directed M-mode echocardiography was performed to derive LVM. Hierarchical multiple regression analyses indicated that follow-up LVM was predicted by initial LVM, weight, height (ht), and gender (males > females; total model R2 = 0.77, P < 0.0001). Predictors of LVM/ht2.7 were initial LVM/ht2.7, weight, ethnicity (blacks > whites), and the aggregate index of blood pressure reactivity (total model R2 = 0.66, P < 0.0001). Youth with LVH at follow-up were taller, heavier, and exhibited greater blood pressure reactivity at initial evaluation. These findings are important since interventional strategies can be developed that target obesity and exaggerated reactivity to stress.
STUDY OBJECTIVES: Methods used to express the severity of oxygen desaturation during polysomnography include the average oxygen saturation (AO2), lowest oxygen saturation (LO2), and the percent of the total time with oxygen saturation level lower than 90% (T<90%). We wanted to determine which one of these methods is least variable during different hours of monitoring. DESIGN: Prospective, observational study. SETTING: Sleep center at a medical university. PATIENTS: One hundred fifty patients with apnea-hypopnea index from 5 to 130. MEASUREMENTS: AO2, LO2, and T<90% were calculated during each of the 8 h of polysomnography. Data for each hour were compared and the Cronbach alpha coefficients were calculated. RESULTS: There was a high degree of correlation among the three methods as well as between each method and the severity of sleep apnea. The mean+/-SD values for each method were as follows: AO2, 92.7+/-5.6; LO2, 68.5+/-19.3; and T<90%, 15.7+/-24.2. The alpha coefficients for these methods were AO2, 0.98; LO2, 0.88; and T<90%, 0.98. In all methods, the data of the first hour were significantly different from the data of the subsequent hours. CONCLUSION: Both AO2 and T<90% methods show less hour to hour variability compared with LO2, and there is more variability in the first hour. Since the AO2 values >90% may not convey the severity of O2 desaturation, T<90% may be the best method of expressing oxygen saturation changes during polysomnography.
Mentally tough' athletes show resilience and an ability to compete during adverse conditions. The present study investigated mental toughness and assessed causal explanations for positive and negative reactions to imagined events using Seligman's Attributional Style Questionnaire. Pessimistic Explanatory style on this scale is a risk factor for negative affect and behavior following negative events. 38 elite athletes in ice hockey were rated for mental toughness by the National Hockey League's scouts on consensually derived criteria. The comparison of players above and below the median split on mental toughness showed composite explanations for negative events that were more internal, stable and global for players above the median. Contrary to predictions, these results suggest that a Pessimistic Explanatory style may benefit hockey performance.
Short courses of oral corticosteroids are widely used to treat asthma. The objective of this study was to assess if one course of oral corticosteroids increases asthmatic children's risk for infections treated with outpatient antibiotics. Using New York State Medicaid claims data on asthmatic children 2-15 years old, we made cohorts of oral corticosteroid users and nonusers. We determined the percentage of children who filled antibiotic prescriptions in the 30 days after index dates. Index dates were dates oral steroids were started (for steroid users) or matched dates (for nonusers). Odds ratios were adjusted for age, month of index date, and prior antibiotic use. Among children not receiving antibiotics on index dates, antibiotic prescriptions were filled in the next 30 days for 438 (20%) of 2145 steroid nonusers and 130 (19%) of 698 steroid users (p=0.30); compared to nonusers, steroid users had an adjusted odds ratio of subsequent antibiotic use of 0.92 (95% confidence interval [CI] 0.73-1.15). Among children receiving antibiotics on index dates, antibiotic prescriptions were filled in the next 30 days for 116 (26%) of 451 steroid nonusers and 50 (19%) of 260 steroid users (p=0.05); compared to nonusers, steroid users had an adjusted odds ratio of subsequent antibiotic use of 0.65 (95% CI 0.53-0.97). We conclude that one course of oral corticosteroids does not increase asthmatic children's risk for infections treated with outpatient antibiotics.
A cultural feasibility study is defined as one that investigates scientific as well as ethical, behavioral, and social issues in the design of clinical trials. The value of such a broadly defined assessment is illustrated through the presentation of two case studies conducted to prepare for clinical trials to reduce maternal-infant HIV transmission on Cité Soleil, Haiti. The first study addressed issues surrounding a trial of breast-feeding and exclusive bottle-feeding among HIV seropositive mothers. The second study focused on the implementation of a double-blind trial of HIV immune globulin and standard immune globulin to be administered to infants of seropositive mothers shortly after birth. Both cases used focus group interviews with mothers and in-depth interviews with key informants to investigate AIDS-related beliefs, acceptability of trial participation, risks to subjects, and community reactions and repercussions to the trial. Findings point to the difficulties posed by attempts to conduct trial involving complex research designs in socially disadvantaged populations. Recommendations highlight the need to consider the community-wide impact of a trial, and the need to undertake extensive educational preparation of participants to ensure informed consent and adherence to protocols.
Hazardous materials used occupationally in Canada are subject to the legislated requirements of the Workplace Hazardous Materials Information System (WHMIS). This paper describes the administrative framework of WHMIS and how toxicological data are evaluated to determine if a substance triggers WHMIS classification for the toxicological endpoints of acute toxicity, skin irritation, eye irritation, corrosion, dermal sensitization, respiratory sensitization, chronic toxicity, mutagenicity, teratogenicity/embryotoxicity, and carcinogenicity. Problems encountered with the information on material safety data sheets are also discussed for each of the toxicological endpoints.
Health visitors and Clinical Medical Officers (CMOs) were trained in parent counselling and worked at home in a highly deprived area with parents of pre-school children with multiple psychosocial problems. Their basic aims were to establish a mutually respectful partnership and to support parents in managing their diverse problems. Detailed evaluation indicated that the Service was highly valued by both parents and referrers, and suggested significant changes, including: improvements in the severity of problems; increased parental self-esteem; decreased levels of parental stress and emotional difficulties; more positive constructions of their children; improvements in the home environment; and decreased child behavioural problems.
Two hundred sixty-eight African-American and white children and their biological mothers participated in the study. The purpose of the study was to examine the potential collective impact of maternal hostile coping styles and perceptions of family functioning upon youths' cardiovascular (CV) functioning 2.4 years later, within the context of SES and ethnicity. The mother completed a set of questionnaires that included the Cook-Medley Hostility Scale and three scales from the Family Environment Scale (FES). Childrens' systolic and diastolic blood pressure (SBP and DBP) and impedance cardiography derived total peripheral resistance (TPR) was measured at rest two years later. Mothers with lower SES and African-American mothers reported higher levels of hostility compared to those with higher SES and white mothers, respectively. Lower SES mothers reported lower levels of family cohesion and expressiveness than higher SES mothers. Whites reported more family conflict and expressiveness than African Americans. African-American and lower SES youth exhibited higher SBP and DBP values than whites and higher SES youth. Among lower SES African-American youth, CV functioning tended to be impacted negatively when their mothers rated themselves high in hostility. Findings suggest that ethnicity and SES may have independent as well as interactive impacts on the influence of maternal coping styles on the CV functioning of their children, particularly those from lower SES backgrounds.
Resting cardiovascular parameters were predicted from anthropometric data, resting baseline cardiovascular data, and cardiovascular responses to three laboratory stressors completed 1 year earlier. Subjects were 106 male and female children (72 Whites, 34 Blacks) aged 6-7 years at the initial evaluation. During initial testing, blood pressure, heart rate, cardiac output, and total peripheral resistance were assessed at rest and also during a forehead cold pressor task, postural change, and treadmill exercise. The same cardiovascular parameters were then assessed at rest 1 year later. After controlling for significant anthropometric measures and the pertinent previous year's resting data, systolic and diastolic responses to the cold pressor were predictive of respective follow-up resting levels. Postural change heart rate responses were predictive of follow-up resting heart rate after controlling for initial resting levels. Exercise cardiac index reactivity predicted follow-up cardiac index after controlling for earlier resting levels and adiposity. Follow-up total peripheral resistance index was predicted by earlier resting levels.
Obesity occurs whenever energy intake exceeds energy expenditure. The ob gene product leptin is a potent anorectic agent when administered to ob/ob mice, but its effects on energy expenditure have not been investigated in detail. The present study was designed to analyze the acute metabolic effects of leptin in vivo. Analysis of oxygen consumption in ob/ob mice demonstrated a reduction in energy expenditure compared with lean controls; this reduction showed a diurnal fluctuation and was most evident during the light cycle. A single intraperitoneal dose of leptin increased oxygen consumption during the light cycle in ob/ob mice, ablating the circadian fluctuation in this parameter. In addition, leptin had a profound effect on fuel selection: the respiratory quotient was markedly reduced, indicating a reduction in carbohydrate oxidation and an increase in fat oxidation. These acute effects of leptin on metabolic parameters are consistent with the selective loss of body fat observed on chronic leptin treatment and suggest that increased energy utilization plays an important role in the anti-obese actions of leptin.
Two hundred forty-six children (96 Whites, of whom 51 were males; 150 African- Americans, of whom 69 were males) with a familial history of essential hypertension (EH) were re-evaluated 5 years after an initial evaluation. During the initial visit anthropometric, demographic, and resting cardiovascular (CV) parameters (designated initial baseline levels) were assessed. These CV parameters (systolic and diastolic blood pressure [BP], heart rate, cardiac output index [CI], and total peripheral resistance index [TPRI] were also measured during postural challenge, a video game challenge, and a cold pressor task. At follow-up, resting CV parameters were again evaluated, and designated as follow-up resting levels. Moderate temporal stability (r range = .43-.56) was observed for all resting CV parameters. Mean stress responses for each CV parameter for all 3 stressors during the initial visit were positively related to the respective CV follow-up resting level. BP stress responses to postural change and video game challenge to be significant independent predictors of future resting BP after controlling for standard EH risk factors. Follow-up resting CI was not predicted by any stress responses, whereas follow-up resting TPRI was predicted by TPRI responses to the video game after controlling for standard Eh risk factors. These results contrast with those from an earlier 1-year follow-up, where stress responses for neither CI nor TPRI predicted follow-up resting levels. It appears that, as children get older, TPRI stress responses play a stronger role in vasoconstrictive function.
OBJECTIVES: This paper describes national trends in mortality of children with sickle cell disease and the settings in which death occurred. METHODS: United States death certificate data from 1968 through 1992 were used to calculate mortality rates of Black children with sickle cell disease 1 to 14 years old. Deaths from trauma, congenital anomalies, and perinatal conditions were excluded. RESULTS: Between 1968 and 1992, mortality rates of Black children with sickle cell disease decreased 41% for 1- to 4-year-olds, 47% for 5- to 9-year-olds, and 53% for 10- to 14-year-olds. During 1986 through 1992, children who died before hospital admission accounted for 41% of deaths among 1- to 4-year-olds, 27% among 5- to 9-year-olds, and 12% among 10- to 14-year-olds. CONCLUSIONS: Survival of Black children with sickle cell disease has improved markedly since 1968. A substantial proportion of deaths continue to occur prior to hospital admission. Trends in sickle cell mortality can be monitored inexpensively with death-certificate data.
The new MCMI-III Posttraumatic Stress Disorder (PTSD) scale was validated on 104 combat veterans who were divided into two groups, PTSD Treatment Group and Non-PTSD Treatment Group. PTSD status was carefully determined by clinical interview and therapists' reports. The Combat Exposure Scale, the Mississippi Scale for Combat-related PTSD, and the Impact of Events Scale were also given. Analysis showed that the MCMI-III PTSD scale had a low internal consistency, but that it significantly differentiated the two groups and significantly correlated to those on other PTSD self-report scales. This scale appeared to be influenced by an acquiescent response style. Further validation studies are needed.
The systemic toxicity of benzothiophene, a sulfur-containing heterocyclic present in petroleum, coal, and their derived products, was studied in male rats following short-term oral exposure. Male Sprague-Dawley rats (130 +/- 20 g) (n = 5 per dose group) were treated with benzothiophene by gavage at dosages of 0, 2, 20 or 200 mg/kg/d for 21 d. In another study, male rats were treated with 0, 100, or 500 ppm benzothiophene via the diet for 28 d. In the gavage study, the 200 mg/kg/d rats showed depressed weight gain, increased relative liver and kidney weights, decreased relative thymus weights, and elevated levels of serum gamma-glutamyltransferase (gamma-GT), hepatic aniline hydroxylase (AH), aminopyrine N-demethylase (APDM), pentoxyresorufin O-dealkylase (PROD), glutathione S-transferase (GST), and UDP-glucuronosyltransferase (UDPGT) activities. A 4.5-fold increase in urine volume on d 14-21 and a transient, 4-fold increase in urinary ascorbic acid on d 1 were also detected. No treatment related changes in urinary N-acetylglucosaminidase (NAGA) activity were observed. Benzothiophene residues were not detected in adipose tissue, liver, and serum of rats in the 200 mg/kg rats, but a small quantity was detected in the urine. In the diet study, animals fed the 500 ppm diet had increased absolute and relative liver weights, elevated AH, APDM, and GST activities, decreased red blood cell count, and minor increases in serum urea nitrogen and glucose. In summary, benzothiophene produced adverse effects in male rats that included increased relative liver and kidney weights and increased urine output. Benzothiophene also caused increases in hepatic drug metabolizing enzyme activities of a phenobarbital type and a transient elevation in urinary ascorbic acid.
Left ventricular (LV) mass is a strong independent predictor of cardiovascular morbidity and mortality. Few longitudinal studies have examined predictors of LV mass in children. This study assessed the contributions of anthropometric, demographic, and cardiovascular parameters (at rest and after exposure to laboratory stressors) as predictors of LV mass 3.6 years after the initial examination in a sample of 68 Caucasian and African-American children 7.9 +/- 0.7 years old. At the initial examination, all subjects had standard anthropometrics measured and hemodynamics assessed at rest and during 3 stressors: postural change, forehead cold stimulation, and treadmill exercise. On the follow-up examination 3 to 4 years later, echocardiographic evaluations were conducted to estimate LV mass and related LV geometry. LV mass and LV internal diameter in diastole were adjusted for linear growth (LV mass/height2.7 and LV internal dimension during diastole/height0.80, respectively). Hierarchical stepwise multiple regression analyses were conducted using parameters significant in univariate comparisons (p < 0.05). Initial weight (R2 = 0.38), height (R2 = 0.42), and cardiac output reactivity to standing and treadmill exercise (final model R2 = 0.55) were significant predictors of LV mass, whereas LV mass/height2.7 was predicted by initial adiposity (R2 = 0.07) and cardiac output and systolic pressure reactivity to postural change (final model R2 = 0.25). Follow-up relative wall thickness was significantly predicted by ethnicity (African-Americans greater than Caucasians, R2 = 0.15), adiposity (R2 = 0.20), and systolic pressure reactivity to postural change (final model R2 = 0.28). These findings suggest the potential benefit of weight control in childhood as a primary prevention for later onset of cardiovascular disease.