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Biomedical subjects

P Stewart

Publications and source records attributed to P Stewart.

At least 37 records · Page 2Linked to original sources
PubMed2000

Costs and effectiveness of community postnatal support workers: randomised controlled trial.

OBJECTIVES: To establish the relative cost effectiveness of postnatal support in the community in addition to the usual care provided by community midwives. DESIGN: Randomised controlled trial with six month follow up. SETTING: Recruitment in a university teaching hospital and care provided in women's homes. PARTICIPANTS: 623 postnatal women allocated at random to intervention (311) or control (312) group. INTERVENTION: Up to 10 home visits in the first postnatal month of up to three hours duration by a community postnatal support worker. MAIN OUTCOME MEASURE: General health status as measured by the SF-36 and risk of postnatal depression. Breast feeding rates, satisfaction with care, use of services, and personal costs. RESULTS: At six weeks there was no significant improvement in health status among the women in the intervention group. At six weeks the mean total NHS costs were pound 635 for the intervention group and pound 456 for the control group (P=0.001). At six months figures were pound 815 and pound 639 (P=0.001). There were no differences between the groups in use of social services or personal costs. The women in the intervention group were very satisfied with the support worker visits. CONCLUSIONS: There was no health benefit of additional home visits by community postnatal support workers compared with traditional community midwifery visiting as measured by the SF-36. There were no savings to the NHS over six months after the introduction of the community postnatal support worker service.

Adolescent↗
PubMed2000

Effects of Great Lakes fish consumption on brain PCB pattern, concentration, and progressive-ratio performance.

This study investigated the effects of consumption of Great Lakes fish on progressive ratio performance, and on the pattern and concentrations of brain polychlorinated biphenyls (PCBs), dichlorodiphenyldichloroethene (DDE), and mirex in the rat. Adult, male Sprague-Dawley rats were fed a 30% diet of either Lake Ontario salmon (LAKE), Pacific Ocean salmon, or lab chow control for 20 or 65 days. Following the treatment regimen, half the rats from each group were sacrificed immediately for gas chromatographic analysis of organochlorine contaminants, and the other half were tested on a multiple fixed-ratio-progressive-ratio reinforcement schedule and then sacrificed for analysis. Consumption of Lake Ontario fish resulted in significantly higher levels of brain PCBs, DDE, and mirex relative to controls, but still well within human exposure ranges (<1 microg/g fat). Consumption of Lake Ontario fish for 20 or 65 days produced an average brain PCB concentration of 457 and 934 ng/g fat, respectively. Consumption of laboratory rat chow or Pacific Ocean salmon for 20 or 65 days produced an average brain PCB concentration of 240, 464, and 441 ng/g fat, respectively. Moreover, both LAKE-fed groups showed a much more heavily chlorinated pattern of brain PCBs than all control groups, as evidenced by both significant increases in the most heavily chlorinated PCB congeners and significant increases in the average chlorine biphenyl. All LAKE brains contained significant concentrations of DDE and mirex, whereas no control brains contained any detectable quantities. Analysis of progressive-ratio performance indicated that LAKE rats responded normally during fixed-ratio schedules but quit significantly sooner than control rats on a progressive-ratio 5 (PR5) schedule, indicating reduced persistence on progressively leaner reinforcement schedules. Analysis of brain PCBs indicated that total PCBs were most strongly related to PR5 performance. These data indicate that consumption by rats of contaminated Lake Ontario fish produces (1) increased concentrations of PCBs, DDE, and mirex in the brain, (2) a more heavily chlorinated distribution of PCBs in the brain, and (3) reduced persistence of progressive-ratio reinforcement schedules. While these behavioral changes are related to brain PCB level, more work is necessary before the effects can be directly attributed to PCBs.

Adult↗
PubMed2000

Biofeedback for fecal incontinence using transanal ultrasonography: novel approach.

PURPOSE: Neosphincter procedures may prove to be the treatment of choice for patients with neuropathic fecal incontinence but are rarely proposed for milder forms of the disease. Biofeedback may prove beneficial to these patients but is yet unproven. The objectives of this study were to develop a method of performing biofeedback using transanal ultrasound to teach the patient to contract repetitively and to determine biologic measures of sphincter function using transanal ultrasound in healthy and incontinent patients. METHODS: Initial uncontrolled studies were performed to determine the compliance, normal values, biologic measures of external sphincter strength (isotonic and isometric fatigue times), and early efficacy data using continence scores and visual analog scale scores. RESULTS: Forty-four patients were assessed during three months, with relative improvements in continence scores (St. Mark's Hospital, 40 percent; Pescatori, 20 percent) and patient and investigator visual analog scale scores (38 percent for both) and measurable increase in biologic fatigue times measured by transanal ultrasound. CONCLUSIONS: Transanal ultrasound seems to be a method of teaching external sphincter contraction and measuring sphincter strength with good initial compliance. Clinically and statistically significant improvements in incontinence scores, visual analog scale scores, and biologic strength of the external sphincter were detected in the short-term follow-up with uncontrolled data. The randomized, controlled trial that we have begun will either confirm or refute these results.

Adult↗
PubMed2000

A novel mutation in a family with non-erythroid variant form of acute intermittent porphyria.

Acute intermittent porphyria (AIP), an autosomal dominant disorder, is divided into two forms, the classical form (more than 95%) and the non-erythroid variant form, according to erythroid porphobilinogen deaminase (PBGD) activity. In the variant form, the PBGD activity is essentially normal. Detection of presymptomatic mutation carriers relies on a DNA test. This variant form of AIP is very rare, with only nine families carrying five different mutations reported in the literature. Here we report a novel G-to-T transversion in the first position of intron 1 of the PBGD gene in a family with this variant form of AIP. We also review all previously reported cases and propose an effective diagnostic approach.

Adult↗
PubMed2000

Factors affecting environmental awareness among Head Start families in Mississippi.

BACKGROUND: Socioeconomic and racial/ethnic disparities in health status in the United States may be attributed in part to environmental injustice and differential exposure to environmental hazards among low-income and/or minority populations. However, the environmental justice movement has historically focused on equity in the siting of point-source polluting facilities, giving little attention to environmental hazards and environmental awareness at the level of the individual household. METHODS: Heads of 763 low-income households participating in Head Start programs in 20 counties of the Mississippi Delta region were surveyed regarding their education, the physical environment of their home and workplace, sources of food and water, awareness of local polluting sites/facilities, knowledge of government agencies, and behaviors that may affect their health or impact their local environment. Survey results were compared to demographic, socioeconomic, and environmental quality indicators. RESULTS: Significant associations existed between both education and race/ethnicity and the responses of survey participants. Being African American was more commonly associated with poor quality-of-life indicators such as renting substandard older homes and living in close proximity to areas of unfavorable watershed quality. Higher education was more commonly and positively associated with indicators of heightened environmental awareness and increased political empowerment. No association was observed between race/ethnicity and the prevalence of polluting facilities. However, a significant association existed between race/ethnicity and indicators of environmental quality/integrity. CONCLUSIONS: Environmental health education interventions that target individual households may be a useful mechanism for increasing the access of low-income communities to government health resources and reducing adverse health effects from the environment. However, racial/ethnic disparities in education and health remain an important consideration.

Awareness↗
PubMed2000

Tick bite and Lyme borreliosis risk at a recreational site in England.

The risk of tick bite and Lyme borreliosis in a forested area in England with public access was studied over a two-year period. Tick infestation levels were high with more than 1000 members of the public reporting for tick removal at a local clinic. Most of the attached ticks were nymphs (82%) and distinct differences in anatomical sites of attachment were observed in children and adults. Children sustained nymphal bites to the head, neck and axilla region much more frequently than adults (48 vs. 10%), whereas adults were bitten on the lower legs more frequently than children (46 vs. 9%). The vegetation was heavily infested with ticks and high numbers were particularly associated with areas used by deer. The average density of nymphs collected from the vegetation was 14.1 per 10 m2 (range 5.1-43.6). Infection rates of these nymphs determined by PCR and indirect IFA ranged from 5.2-17.0%, and the genospecies Borrelia valaisiana and B. garinii were detected, suggesting that birds may be important reservoir hosts in this area. It is estimated that, at the level of tick challenge observed here, at least 50 persons per year may be bitten by infected ticks at this site. However, no cases of Lyme borreliosis have been reported through the clinic follow-up procedure, and sera from 19 forest workers were negative for antibody to B. burgdorferi sensu lato. Despite the high challenge from tick bites, this particular recreational forest site poses a low risk of infection to the general public, and prophylactic antibiotic treatment or serological testing following a bite is not justified.

Adult↗
PubMed2000

Exposure assessment in the occupational setting.

Exposure assessment, the first step in risk assessment, has traditionally been performed for a variety of purposes. These include compliance determinations; management of specific programs that are implemented by comparison with an occupational exposure limit (such as medical surveillance, training, and respiratory protection programs); task/source investigations for determination of exposure control strategies; epidemiologic studies; worker compensation/toxic tort cases; health complaint or problem investigations; risk assessment and management; and evaluation of future changes in the workplace (e.g., introduction of a new chemical). Each purpose requires slightly different approaches, but there are also many similarities. The goal of this paper is to identify a general approach to assessing exposures that can be used for all purposes with only slight modifications. Five components of exposure assessments are identified: collection of data, identification of the hazard, selection of exposure metrics, definition of exposure groups and estimation of the exposures. The characteristics of these components for each type of assessment are discussed. From this review, it is clear that there is substantial overlap across the types of assessment. A single exposure assessment program is suggested that encompasses all the needs of these assessments and incorporates assessment of exposures for an entire workforce at a site at minimal cost by using prediction models and validation with measurements.

Hazardous Substances↗
PubMed2000

A homokaryotic derivative of a Phanerochaete chrysosporium strain and its use in genomic analysis of repetitive elements.

Analysis of complex gene families in the lignin-degrading basidiomycete Phanerochaete chrysosporium has been hampered by the dikaryotic nuclear condition. To facilitate genetic investigations in P. chrysosporium strain BKM-F-1767, we isolated a homokaryon from regenerated protoplasts. The nuclear condition was established by PCR amplification of five unlinked genes followed by probing with allele-specific oligonucleotides. Under standard nitrogen-limited culture conditions, lignin peroxidase, manganese peroxidase, and glyoxal oxidase activities of the homokaryon were equivalent to those of the parental dikaryon. We used the homokaryon to determine the genomic organization and to assess transcriptional effects of a family of repetitive elements. Previous studies had identified an insertional mutation, Pce1, within lignin peroxidase allele lipI2. The element resembled nonautonomous class II transposons and was present in multiple copies in strain BKM-F-1767. In the present study, three additional copies of the Pce1-like element were cloned and sequenced. The distribution of elements was nonrandom; all localized to the same 3.7-Mb chromosome, as assessed by segregation analysis and Southern blot analysis of the homokaryon. Reverse transcription-PCR (RT-PCR) showed that Pce1 was not spliced from the lipI2 transcript in either the homokaryon or the parental dikaryon. However, both strains had equivalent lignin peroxidase activity, suggesting that some lip genes may be redundant.

Chromosome Mapping↗
PubMed2000

Altered stationary-phase response in a Borrelia burgdorferi rpoS mutant.

The homolog of the chromosomally encoded stationary-phase sigma factor RpoS in Borrelia burgdorferi was inactivated using gyrB(r) as a selectable marker. Two-dimensional nonequilibrium pH gradient electrophoresis of stationary-phase cell lysates identified at least 11 differences between the protein profiles of the rpoS mutant and wild-type organisms. Wild-type B. burgdorferi had a growth phase-dependent resistance to 1 N NaCl, similar to the stationary-phase response reported for other bacteria. The B. burgdorferi rpoS mutant strain was less resistant to osmotic stress in stationary phase than the isogenic rpoS wild-type organism. The results indicate that the B. burgdorferi rpoS homolog influences protein composition and participates in stationary-phase-dependent osmotic resistance. This rpoS mutant will be useful for studying regulation of gene expression in response to changing environmental conditions.

Bacterial Proteins↗
PubMed2000

Costs and benefits of community postnatal support workers: a randomised controlled trial.

OBJECTIVES: This study aimed to measure the effect and the total cost per woman of providing postnatal support at home, based on a Dutch model. The research hypothesis was furnished by some existing evidence that postnatal support could reduce the risk of postnatal depression and encourage breastfeeding. DESIGN: The randomised controlled trial aimed to measure differences in health status in a group of women who were offered postnatal support from a community midwifery support worker (SW) compared with a control group of women who were not offered this support. Women were followed-up by postal questionnaire at 6 weeks and 6 months postnatally. SETTING AND SUBJECTS: All women who delivered a baby at the recruiting hospital were eligible to take part in the trial if they lived within the study area, were aged 17 years or over, and could understand English. INTERVENTION: The intervention consisted of the SW offering practical and emotional support and to help women rest and recover after childbirth. The SW offered ten visits in the first 28 days postnatally, for up to 3 hours per day. The SW's activities included housework, talking with the mother, and care for the baby or other siblings. The service was provided in addition to routine visits by the community midwife. MAIN OUTCOME MEASURES: The primary outcome was the general health perception domain of the Short Form-36 at 6 weeks. Secondary outcomes were mean Edinburgh Postnatal Depression Scale (EPDS), Duke Functional Social Support (DUFSS) scores and breastfeeding rates. RESULTS: The 623 randomised women were well-matched by group with a good response to follow-up. At 6 weeks there was no evidence of a significant difference between the two groups for the primary outcome. There was a non-significant trend for the control group to have better mean DUFSS and EPDS scores at 6 weeks. Breastfeeding rates were not significantly different at follow-up. At 6 months, both groups had similar health status. Satisfaction with the service was higher than for all other services received. The incremental cost of introducing the service comprised setting up and running the service. There were no differences between the groups in other resource use (general practitioner contacts, hospital services, prescriptions or medicines bought for mothers and babies) to 6-month follow-up. The total mean NHS cost to 6-month follow-up for the intervention group was pound180 per woman greater than for the control group (confidence interval, pound79.60, pound272.40). CONCLUSIONS: Although women valued the service, there was no evidence of any health benefit at the 6-week or 6-month follow-up, no difference in use of NHS services, and the additional cost of the service provision would be around pound 180 per woman.

Adolescent↗
PubMed2000

Canadian national high blood pressure prevention and control strategy.

Despite major efforts to prevent and control high blood pressure, it is one of the most common and important health problems facing Canadians. To address this issue, Health Canada, in collaboration with the Canadian Coalition for High Blood Pressure Prevention and Control, established an Expert Working Group to prepare a national strategy. The present report outlines a strategy to prevent and control high blood pressure. It is directed at policy makers at the local, provincial, and/or territorial and national levels in both the health and nonhealth sectors. The strategy is based on current research and expertise. A multifaceted, comprehensive approach is proposed because there is no one intervention that will accomplish the goal of improving the health of Canadians through high blood pressure prevention and control. The present report focuses on the general population. It does not address the unique needs of children, pregnant women or aboriginal peoples. Each of these groups needs to be studied in its own right, and, in particular, with the involvement of aboriginal people themselves. An implementation committee has been established to realize this strategy, and the Canadian Hypertension Society is a key stakeholder in this effort. Several initiatives are underway. Strong advocates are necessary to increase public awareness and to support the system changes required for a successful public health approach to reduce the prevalence of hypertension and its complications.

Adult↗
PubMed2000

DNA exchange and insertional inactivation in spirochetes.

Spirochetes have complex life cycles and are associated with a number of diseases in humans and animals. Despite their significance as pathogens, spirochete genetics are in their early stages. However, gene inactivation has been achieved in Borrelia burgdorferi, Brachyspira hyodysenteriae, and Treponema denticola. Here, we review methods that have been used in spirochetes for gene inactivation and DNA exchange, with a primary focus on B. burgdorferi. We also describe factors influencing electrotransformation in B. burgdorferi. In summary, optimal transformation frequencies are obtained with log phase bacteria, large amounts of DNA (up to 50 microg per transformation), and high field strength (12.5-37.5 kV/cm). Infectious B. burgdorferi isolates transform with frequencies 100-fold lower than those found for high passage, non-infectious strains. Surface characteristics of the bacteria, which often correlate with infectivity, are among the obstacles to effective transformation by electroporation.

Animals↗
PubMed2000

Prenatal exposure to PCBs and infant performance on the fagan test of infant intelligence.

A sample of infants was examined at conceptual age 67 weeks (6-month testing, N=230), and again at conceptual age 92 weeks (12-month testing, N=216) using the Fagan Test of Infant Intelligence (FTII). Analysis of the results revealed a dose-dependent relationship between total umbilical cord-blood PCB levels and poorer FTII performance at both ages. A similar relationship was observed using a subset of the persistent and heavily chlorinated PCB congeners associated with Lake Ontario fish consumption (septa-, octa-, and nonachlorinated biphenyls) in children tested at 12-months but not at 6-months. These data replicate previous research (Jacobson et al., 1985) which demonstrated a dose-dependent relationship between prenatal PCB exposure and FTII performance in infants of Lake Michigan fisheaters. Analyses of FTII scores with cord-blood DDE and maternal hair methylmercury (MeHg) revealed no significant associations between FTII performance and either of these toxicants. The latter results replicate those of Myers et al., (1995) who found no effect of MeHg on FTII performance in Seychellois infants.

Adult↗
PubMed1999

The impact of obesity and disease on busulfan oral clearance in adults.

The apparent oral clearance (CL/F, mL/min) of busulfan was measured in 279 adolescent and adult patients. Significant (P <.05) determinants of CL/F by linear regression were: actual body weight (BW; r2 = 0.300), body surface area (BSA; r2 = 0.277), adjusted ideal body weight (AIBW; r2 = 0.265), and ideal body weight (IBW; r2 = 0.173); whereas body mass index (BMI), height, age, gender, and disease were less important predictors. CL/F (mL/min) for normal weight patients (BMI, 18 to 27 kg/m2) was 16.2% lower (P <.001) than for obese patients (BMI, 27 to 35 kg/m2). Thus, expressing CL/F relative to BW did not eliminate statistically significant differences between normal and obese patients. However, busulfan CL/F expressed relative to BSA (110 +/- 24 v 110 +/- 24 mL/min/m2, P = 1.0) or AIBW (3.04 +/- 0.65 v 3.19 +/- 0.67 mL/min/kg, P =.597) were similar in normal and obese patients. Non-Hodgkin's lymphoma patients (n = 10) had approximately 32% lower mean busulfan CL/F expressed relative to BW, BSA, or AIBW compared with patients with chronic myelogenous leukemia (n = 73). Routine dosing on the basis of BSA or AIBW in adults and adolescents does not require a specific accommodation for the obese. However, dosing based on BSA may be improved by considering CL/F differences in certain diseases. Adjusting dose for body size or disease does not diminish interpatient variability sufficiently to obviate plasma level monitoring in many indications.

Administration, Oral↗
PubMed1999

Assessment of prenatal exposure to PCBs from maternal consumption of Great Lakes fish: an analysis of PCB pattern and concentration.

The current study was designed to assess the pattern and concentration of prenatal PCB exposure in the newborns of women who consumed Great Lakes fish. We compared the pattern and concentration of umbilical cord blood PCBs of 145 women who reported never having consumed Great Lakes fish to 134 women who reported consuming at least 40 PCB-equivalent fish lbs of Great Lakes fish in their lifetime (Lonky et al., 1996). Although the average levels of total PCBs in cord blood were exceedingly low (approximately 1.0 ppb), the data clearly indicated that both the proportion (mol%) and the absolute concentration (ppb) of the most heavily chlorinated and persistent PCB homologues (homologues C17-C19) were markedly elevated in the cord blood of fish eaters. This effect grew markedly as a function of the total PCBs detected in the sample. Moreover, the concentration of the most heavily chlorinated PCB homologues was significantly dependent on how recently the fish were consumed relative to pregnancy. The order of highly chlorinated PCB concentration was consumed fish throughout pregnancy > consumed fish up until pregnancy > stopped consuming fish in 1984 > never consumed Lake Ontario fish. In contrast, PCB homologues of light (Cl1-Cl3) or moderate (Cl4-Cl6) chlorination were unrelated to fish consumption. Analysis of the relationship between the PCB homologues in cord blood and their homologues in breast milk provided further converging evidence of these findings. While PCB homologues of light (Cl1-Cl3) or moderate (Cl4-Cl6) chlorination did not correlate with their breast milk homologues, the most persistent and heavily chlorinated PCB homologues (Cl7-Cl9) were significantly and positively correlated with breast milk levels. These data indicate that the most heavily chlorinated PCBs provide valid and reliable exposure information in a lean medium such as cord blood. We conclude that maternal consumption of Great Lakes fish increases the risk of prenatal exposure to the most heavily chlorinated PCB homologues.

Adult↗