Biomedical subjects

R Thompson

Publications and source records attributed to R Thompson.

At least 55 records · Page 3Linked to original sources

PubMed2001

Analyzing variety by environment data using multiplicative mixed models and adjustments for spatial field trend.

The recommendation of new plant varieties for commercial use requires reliable and accurate predictions of the average yield of each variety across a range of target environments and knowledge of important interactions with the environment. This information is obtained from series of plant variety trials, also known as multi-environment trials (MET). Cullis, Gogel, Verbyla, and Thompson (1998) presented a spatial mixed model approach for the analysis of MET data. In this paper we extend the analysis to include multiplicative models for the variety effects in each environment. The multiplicative model corresponds to that used in the multivariate technique of factor analysis. It allows a separate genetic variance for each environment and provides a parsimonious and interpretable model for the genetic covariances between environments. The model can be regarded as a random effects analogue of AMMI (additive main effects and multiplicative interactions). We illustrate the method using a large set of MET data from a South Australian barley breeding program.

Analysis of Variance↗

PubMed2001

Spontaneous bacterial peritonitis--in-hospital mortality, predictors of survival, and health care costs from 1988 to 1998.

OBJECTIVES: Spontaneous bacterial peritonitis (SBP) is a complication of end-stage liver disease with a reported mortality of 30-50%. In this study, we investigated the outcome of all patients admitted to Maryland hospitals with SBP from 1988 to 1998. Main outcomes considered included trends in survival rates over time, changes in the length of stay, total health care costs, and variables that predicted survival rates. METHODS: We used the Maryland Health Services Cost Review database of all patients admitted to Maryland hospitals with an International Classification of Diseases (Ninth Revision) code for both peritonitis and cirrhosis from 1988 to 1998. RESULTS: A total of 348 patients were admitted with an in-hospital mortality of 32.6%; there was no significant change in mortality rate during this period. The survival rate was similar in the university and community hospitals. In the logistic regression analysis, age (p = 0.001) and intensive care unit stay (p = 0.0001) were found to significantly influence the survival rates; those patients who had an intensive care unit stay were 2.8 times more likely to die than those who did not have an intensive care unit stay, controlling for age. The average length of hospital stay remained unchanged (13.5 +/- 12.7 days) during the study period. Although the median hospital charge (excluding professional fees) remained unchanged, mean inflation-adjusted charges increased from $7,897 in 1988 to $25,902 in CONCLUSIONS: The mortality rate associated with SBP has remained unchanged over an 11-yr period from 1988 to 1998. The mortality showed a strong correlation with age and intensive care unit stay. The median hospital stay and median charges remained unchanged during this period, but mean costs increased significantly because of increased use of resources by a few patients.

Adult↗

PubMed2001

Ventricular enlargement in adults with profound mental retardation who demonstrate violent/destructive behaviors.

The authors determined brain ventricular size (ventricular brain ratio [VBR]) in 39 ambulatory adult mentally retarded individuals who did or did not require psychotropic medication for violent/destructive behavior. The mean VBR of mentally retarded patients who required psychotropic medication was significantly greater than the VBR of those who did not require such medication.

Adolescent↗

PubMed2001

Untangling the impact of sexual abuse on HIV risk behaviors among youths in foster care.

This study investigates the interrelationships among childhood sexual abuse, other types of child maltreatment, emotional and behavioral problems, and HIV risk behaviors in a sample of 167 adolescents, aged 15-19, participating in an independent living preparation program in one midwestern county. Thirty-three percent of the youths identified as white and 67% as youths of color. The sample was almost evenly split by gender (51% male and 49% female). Thirty-five percent of the youths (n = 59) reported some form of sexual abuse; 21 reported unwanted touching, with no unwanted intercourse, and 38 reported unwanted intercourse. Multivariate analyses demonstrated a significant relationship between the severity of sexual abuse and youths' recent HIV risk behaviors, after accounting for the contribution of other childhood trauma and emotional and behavioral problems. The findings support the need for HIV prevention programs targeting sexually abused youths.

Adolescent↗

PubMed2001

In vitro high throughput screening of compounds for favorable metabolic properties in drug discovery.

Drug metabolism can have profound effects on the pharmacological and toxicological profile of therapeutic agents. In the pharmaceutical industry, many in vitro techniques are in place or under development to screen and optimize compounds for favorable metabolic properties in the drug discovery phase. These in vitro technologies are meant to address important issues such as: (1) is the compound a potent inhibitor of drug metabolising enzymes (DMEs)? (2) does the compound induce the expression of DMEs? (3) how labile is the compound to metabolic degradation? (4) which specific enzyme(s) is responsible for the compound's biotransformation? and (5) to which metabolites is the compound metabolized? Answers to these questions provide a basis for judging whether a compound is likely to have acceptable pharmacokinetic properties in vivo. To address these issues on the increasing number of compounds inundating the drug discovery programs, high throughput assays are essential. A combination of biochemical advances in the understanding of the function and regulation of DMEs (in particular, cytochromes P450, CYPs) and automated analytical technologies are revolutionizing drug metabolism research. Automated LC-MS based metabolic stability, fluorescence, radiometric and LC-MS based CYP inhibition assays are now in routine use. Automatible models for studying CYP induction based on enzyme activity, quantitative RT-PCR and reporter gene systems are being developed. We will review the utility and limitations of these HTS approaches and highlight on-going developments and emerging technologies to answer metabolism questions at the different stages of the drug discovery process.

Animals↗

PubMed2001

Synthesis of direct and maternal genetic components of economically important traits from beef breed-cross evaluations.

Published information on relative performance of beef breed crosses was used to derive combined estimates of purebred breed values for predominant temperate beef breeds. The sources of information were largely from the United States, Canada, and New Zealand, although some European estimates were also included. Emphasis was on maternal traits of potential economic importance to the suckler beef production system, but some postweaning traits were also considered. The estimates were taken from comparison studies undertaken in the 1970s, 1980s and 1990s, each with representative samples of beef breeds used in temperate agriculture. Weighting factors for breed-cross estimates were derived using the number of sires and offspring that contributed to that estimate. These weights were then used in a weighted multiple regression analysis to obtain single purebred breed effects. Both direct additive and maternal additive genetic effects were estimated for preweaning traits. Important genetic differences between the breeds were shown for many of the traits. Significant regression coefficients were estimated for the effect of mature weight on calving ease, both maternal and direct additive genetic, survival to weaning direct, and birth weight direct. The breeds with greater mature weight were found to have greater maternal genetic effects for calving ease but negative direct genetic effects on calving ease. A negative effect of mature weight on the direct genetic effect of survival to weaning was observed. A cluster analysis was done using 17 breeds for which information existed on nine maternal traits. Regression was used to predict breed-cross-specific heterosis using genetic distance. Only five traits, birth weight, survival to weaning, cow fertility, and preweaning and postweaning growth rate had enough breed-cross-specific heterosis estimates to develop a prediction model. The breed biological values estimated provide a basis to predict the biological value of crossbred suckler cows and their offspring.

Animals↗

PubMed2001

Effect of aprotinin (trasylol) on the inflammatory and thrombotic complications of conventional cardiopulmonary bypass surgery.

Before the discovery of its hemostatic properties, aprotinin was thought of as a potential anti-inflammatory agent. Its clinical introduction in 1987 to prevent blood loss during cardiac surgery [Royston 1987, van Oeveren 1987] led to its anti-inflammatory benefits being largely overlooked in favor of a vigorous debate centering on whether aprotinin may be pro-thrombotic when given to patients. In this article, we summarize evidence for the anti-inflammatory activity of aprotinin and discuss our recent contributions in this area. We also summarize the state of the thrombosis debate and discuss our recent evidence from purified platelets which shows that aprotinin is simultaneously hemostatic yet anti-thrombotic.

Animals↗

PubMed2001

Validity and efficiency of screening for history of depression by self-report.

Because of the recurrent nature of depression, there is a need for a rapid means of screening for history of depression that is either valid in itself or an efficient means of identifying respondents needing further assessment. This study examined the validity and efficiency of assessment of lifetime history of depression by self-report screening questions in comparison with the results of a structured interview assessment conducted a year earlier. Self-reported lifetime 2-week mood disturbance was unrelated to the results of the earlier interview. Self-report of treated episodes of mood disturbance were related to interview-assessed history of depression, but too modestly for practical applications. Self-report of past depression was more strongly related to concurrent distress than to the earlier interview assessment of history of depression. Implications of these findings for screening and assessment of history of depression are discussed.

Adult↗

PubMed2000

The intrinsic function of a motor system--from ion channels to networks and behavior.

The forebrain, brainstem and spinal cord contribution to the control of locomotion is reviewed in this article. The lamprey is used as an experimental model since it allows a detailed cellular analysis of the neuronal network underlying locomotion. The focus is on cellular mechanisms that are important for the pattern generation, as well as different types of pre- and postsynaptic modulation. This experimental model is bridging the gap between the molecular and cellular level to the network and behavioral level.

Animals↗

PubMed2000

Release of synaptic zinc is substantially depressed by conventional brain slice preparations.

Research on synaptically-released zinc is frequently done in vitro with acute brain slice preparations. We show here the in vitro hippocampal slice preparation has two major pitfalls for zinc research. First, up to 50% of the synaptic zinc is lost during slice cutting and/or the first 10 min of slice incubation, with the losses being most pronounced on the edges of the slice. Second, the release of the remaining zinc from a slice is substantially depressed (up to 50%) at the low temperatures (32 degrees C) typically used for brain slice studies. In concert, these effects reduce zinc release about 75% in vitro, compared to in vivo. Implications for research on synaptically-released zinc are discussed.

Animals↗

PubMed2000

Workforce planning. Remote control.

The current system of medical manpower planning fails to balance doctors' training requirements with the demands of the NHS. Urgent action is needed to avoid a manpower crisis. Specialist registrars regularly have to leave their hospitals for training sessions, forcing the cancellation of sessional work. Hospital medicine is relying heavily on locums and doctors from abroad. Consultants should be given the junior support they need in order to provide a proper service, possibly through increasing the time spent at senior house officer level.

Consultants↗

PubMed2000

The effect of orthodontic referral guidelines: a randomised controlled trial.

OBJECTIVE: To develop and evaluate the effectiveness of referral guidelines for the referral of orthodontic patients to consultant and specialist practitioner orthodontists. DESIGN: Single centre randomised controlled trial with random allocation of referral guidelines for orthodontic treatment to general dental practitioners. SETTING: Hospital orthodontic departments and specialist orthodontic practices in Manchester and Stockport. SUBJECTS: General dental practitioners and the patients they referred for orthodontic treatment. MAIN OUTCOME MEASURE: Appropriateness of referral, defined as whether the patient was accepted for orthodontic treatment. RESULTS: The referral guidelines did not reduce the number of inappropriate referrals. CONCLUSIONS: Referral guidelines for orthodontic referrals did not influence the behaviour of the general dental practitioners. More research into the optimum methods of dissemination and implementation of referral guidelines for use in the general dental service is needed.

Adolescent↗

PubMed2000

Chromatographic separation of 3,4-difluorophenylacetic acid and its positional isomers using five different techniques.

The separation of five positional isomers from 3,4-difluorophenylacetic acid was investigated using normal- and reversed-phase high-performance liquid chromatography, capillary zone electrophoresis, gas chromatography and supercritical fluid chromatography. Operating parameters of each technique, such as temperature, type of stationary phase, mobile phase pH, ionic strength, organic modifiers and additives were varied in order to elucidate the separation mechanisms. Based on the advantages and disadvantages of each methodology, a simple and practical RPLC method was selected. The method was validated in terms of linearity, limit of detection, accuracy, recovery, ruggedness and precision.

Acetates↗

PubMed2000

Helmets for preventing head and facial injuries in bicyclists.

BACKGROUND: Each year, in the United states, approximately 900 persons die from injuries due to bicycle crashes and over 500,000 persons are treated in emergency departments. Head injury is by far the greatest risk posed to bicyclists, comprising one-third of emergency department visits, two-thirds of hospital admissions, and three-fourths of deaths. Facial injuries to cyclists occur at a rate nearly identical to that of head injuries. Although it makes inherent sense that helmets would be protective against head injury, establishing the real-world effectiveness of helmets is important. A number of case-control studies have been conducted demonstrating the effectiveness of bicycle helmets. Because of the magnitude of the problem and the potential effectiveness of bicycle helmets, the objective of this review is to determine whether bicycle helmets reduce head, brain and facial injury for bicyclists of all ages involved in a bicycle crash or fall. OBJECTIVES: To determine whether bicycle helmets reduce head, brain and facial injury for bicyclists of all ages involved in a bicycle crash or fall. SEARCH STRATEGY: We searched The Cochrane Controlled Trials Register, MEDLINE, EMBASE, Sport, ERIC, NTIS, Expanded Academic Index, CINAHL, PsycINFO, Occupational Safety and Health, and Dissertations Abstracts. We checked reference lists of past reviews and review articles, studies from government agencies in the United States, Europe and Australia, and contacted colleagues from the International Society for Child and Adolescent Injury Prevention, World Injury Network, CDC funded Injury Control and Research Centers, and staff in injury research agencies around the world. SELECTION CRITERIA: Controlled studies that evaluated the effect of helmet use in a population of bicyclists who had experienced a crash. We required that studies have complete outcome ascertainment, accurate exposure measurement, appropriate selection of the comparison group and elimination or control of factors such as selection bias, observation bias and confounding. DATA COLLECTION AND ANALYSIS: Five published studies met the selection criteria. Two abstractors using a standard abstraction form independently abstracted data. Odds ratios with 95% CI were calculated for the protective effect of helmet for head and facial injuries. Study results are presented individually. Head and brain injury results were also summarized using meta-analysis techniques. MAIN RESULTS: No randomized controlled trials were found. This review identified five well conducted case control studies which met our selection criteria. Helmets provide a 63%-88% reduction in the risk of head, brain and severe brain injury for all ages of bicyclists. Helmets provide equal levels of protection for crashes involving motor vehicles (69%) and crashes from all other causes (68%). Injuries to the upper and mid facial areas are reduced 65%. REVIEWER'S CONCLUSIONS: Helmets reduce bicycle-related head and facial injuries for bicyclists of all ages involved in all types of crashes including those involving motor vehicles.

Bicycling↗

PubMed2000

Anti-VEGF antibody suppresses primary tumor growth and metastasis in an experimental model of Wilms' tumor.

BACKGROUND/PURPOSE: Vascular endothelial growth factor (VEGF) has been shown previously to correlate with tumor growth and metastasis in an experimental model of anaplastic Wilms' tumor. The authors hypothesized that treatment with anti-VEGF antibodies would suppress both primary tumor growth and metastasis in this model. METHODS: Tumors were induced in the right kidneys of nude mice by the injection of cultured Wilms' tumor cells. After 1 week, anti-VEGF treatment was begun with injection of either vehicle or an anti-VEGF antibody intraperitoneally. Mice were killed after 4.5 weeks of treatment and tumor weights and the incidence of metastases evaluated. RESULTS: Anti-VEGF treatment resulted in a greater than 95% reduction in tumor weight (P < .0001). Anti-VEGF treatment also abolished the establishment of lung metastases (40% in control animals, P < .003). Cessation of treatment resulted in rebound tumor growth. CONCLUSION: Anti-VEGF therapy can suppress both primary tumor growth and the establishment of metastases in experimental anaplastic Wilms' tumor.

Animals↗

PubMed2000

Inherited disorders of transport in the liver.

There has been a recent explosion in our understanding of hepatic transport processes. Much of this has resulted from the investigation of human diseases involving the liver and the use of animal models. The physiological roles of many of these transporters have been well characterised previously but have, until now, been resistant to molecular cloning.

ATP-Binding Cassette Transporters↗

PubMed2000

Marker-assisted selection using ridge regression.

In cross between inbred lines, linear regression can be used to estimate the correlation of markers with a trait of interest; these marker effects then allow marker assisted selection (MAS) for quantitative traits. Usually a subset of markers to include in the model must be selected: no completely satisfactory method of doing this exists. We show that replacing this selection of markers by ridge regression can improve the mean response to selection and reduce the variability of selection response.

Genetic Markers↗

PubMed2000

Anopheles arabiensis and An. funestus are equally important vectors of malaria in Matola coastal suburb of Maputo, southern Mozambique.

Transmission characteristics of malaria were studied in Matola, a coastal suburb of Maputo, the capital City, in southern Mozambique, from November 1994 to April 1996. The local climate alternates between cool dry season (May-October) and hot rainy season (November-April) with mean annual rainfall 650-850 mm. Saltmarsh and freshwater pools provide mosquito breeding sites in Matola. Malaria prevalence reached approximately 60% among people living nearest to the main breeding sites of the vectors. Plasmodium falciparum caused 97% of malaria cases, others being P. malariae and P. ovale. Potential malaria vector mosquitoes (Diptera: Culicidae) collected at Matola during daytime indoor-resting (n = 1021) and on human bait at night (n = 5893) comprised 12% Anopheles coustani Laveran (93% biting outdoors), 46% An. funestus Giles (68% biting indoors) and 42% An. gambiae Giles sensu lato (60% biting outdoors). All 215 specimens of An. gambiae s.l. identified genetically were An. arabiensis Patton. Anopheles funestus populations remained stable throughout the year, whereas densities of the An. gambiae complex fluctuated considerably, with An. arabiensis peaking during the rainy season. No concomitant rise in malaria incidence was observed. Human landing indices of An. funestus and An. arabiensis averaged 1.8 and 3.8 per man-night, respectively. Overall Plasmodium sporozoite rates were 2.42+/-1.24% in 2181 An. funestus and 1.11+/-1.25% in 1689 An. arabiensis dissected and examined microscopically. Mean daily survival rates were 0.79 for both vector species. Estimated infective bites/person/year were 15 An. funestus and 12 An. arabiensis. Biting rates were greatest at 2100-24.00 hours for An. funestus (68% endophagic) and 21.00-03.00 hours for An. arabiensis (40% endophagic). The entomological inoculation rate (EIR) declined sharply over very short distances (50% per 90m) away from breeding-sites of the vectors. Consequently, P. falciparum prevalence among Matola residents was halved 350 m within the town. Implications for the protective effectiveness of a 'cordon sanitaire' by residual house-spraying and/or the use of insecticide-treated bednets are discussed.

Animals↗