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Biomedical subjects

D J Wright

Publications and source records attributed to D J Wright.

At least 37 records · Page 2Linked to original sources
PubMed2002

Effect of cabbage cultivars with varying levels of resistance to aphids on the performance of the parasitoid, Aphidius colemani (Hymenoptera: Braconidae).

The effect of aphid resistance in plant cultivars on parasitism of Myzus persicae (Sulzer) and Brevicoryne brassicae (Linnaeus) by Aphidius colemani Viereck was investigated under laboratory conditions using three cultivars of common cabbage, Brassica oleracea var. capitata. Significantly greater aphid populations were found on cv. Derby Day (green-leaved, susceptible to both aphid species), regardless of the presence or absence of parasitoids, compared with cv. Minicole (green-leaved, partially resistant with antibiosis factors for B. brassicae) or cv. Ruby Ball (red-leaved, partially resistant with antixenosis factors for B. brassicae). Minicole had the greatest proportion of parasitized aphids and Derby Day the least. A significantly lower percentage of emerged parasitoids were recorded on Minicole for both aphid species compared with Derby Day and Ruby Ball. The implication of the results are discussed in relation to the integrated control of aphids.

Animals↗
PubMed2002

Tritrophic interactions between cabbage cultivars with different resistance and fertilizer levels, cruciferous aphids and parasitoids under field conditions.

Tritrophic interactions involving cabbage Brassica oleracea var. capitata cultivars +/- fertilizer, Brevicoryne brassicae (Linnaeus) and Myzus persicae (Sulzer), and the parasitoids Diaeretiella rapae (M'cIntosh) and Aphidius sp. were conducted in 1998 and 1999. Brevicorne brassicae was the dominant aphid species on all cultivars +/- fertilizer, except for some treatments in late season 1998. Ruby Ball (red-leaved with antixenosis factors for B. brassicae alates) +/- fertilizer was consistently less colonized by aphids in early stages of plant growth, although only significantly so compared with Derby Day (green-leaved, susceptible to aphids) without fertilizer for B. brassicae and Minicole (green-leaved with antibiosis factors for B. brassicae) with fertilizer for M. persicae. In early 1999, only B. brassicae was present and no significant differences between cultivars were seen. In the mid to late season 1998, the highest aphid infestations were usually found on Derby Day, although only significantly so for B. brassicae, in some treatments. In 1999, higher aphid infestations were observed on Derby Day in mid to late season and some significant differences were found for M. persicae as well as for B. brassicae. In both years, Ruby Ball had the greatest mummy:aphid ratios early season, with no consistent difference between the other cultivars. Later in the season, mummy:aphid ratios were generally highest on Minicole. Parasitism differed in seasonal occurrence and relative abundance. Diaeretiella rapae mummies were found earlier than Aphidius sp. There was evidence of a beneficial interaction between the degree of plant resistance and biological control in early to mid season.

Animals↗
PubMed2001

Determinants of HIV-1 shedding in the genital tract of women.

BACKGROUND: Plasma HIV-1 RNA concentration has been the best predictor for risk of heterosexual and perinatal transmission. However, direct contact with HIV-1 present locally in the genital tract might be necessary for transmission. We aimed to assess the relation between HIV-1 shedding (RNA or culturable virus) in female genital secretions and other factors that might affect HIV-1 shedding. METHODS: This was a cross-sectional study within the Women's Interagency HIV Study (WIHS), a prospective longitudinal cohort study of HIV-infected women. We enrolled 311 HIV positive women from Jan 30, 1997 to July 1, 1998. We did clinical assessments, cultured HIV-1, and measured RNA in peripheral blood mononuclear cells (PBMC) and genital secretions. We compared the results with univariate and multivariate analyses. Presence of HIV-1 RNA or culturable virus in genital secretions was defined as HIV-1 shedding. FINDINGS: HIV-1 RNA was present in genital secretions of 57% (152/268) of women whereas infectious virus was detected only in 6% (17/271). Genital tract HIV-1 shedding was found in 80% (130/163) of women with detectable plasma RNA and 78% (116/148) of women with positive PBMC cultures. 33% (27/83) of women with less than 500 copies/mL plasma RNA and 39% (35/90) of those with negative PBMC cultures also had genital tract shedding. INTERPRETATION: Plasma RNA concentration, both qualitatively and quantitatively, was the most important factor in predicting genital HIV-1 shedding, even among women receiving potent antiretroviral therapy. However, HIV-1 shedding did occur in women with less than 500 copies/mL plasma HIV-1 RNA. This finding suggests that a separate reservoir of HIV-1 replication may exist in some women.

Adult↗
PubMed2001

Variation of human immunodeficiency virus type 1 viral RNA levels in the female genital tract: implications for applying measurements to individual women.

The short-term detection and variability of human immunodeficiency virus type 1 (HIV-1) RNA level was assessed in the blood plasma and genital tracts of 55 HIV-1-infected women. Specimens were collected weekly for 8 weeks from the endocervical canal with wicks and cytobrushes and from the ectocervix and vagina with cervicovaginal lavage. In all, 48 women (87.3%) had detectable genital tract HIV-1 RNA at > or =1 collection times. HIV-1 RNA levels varied least in specimens from endocervical canal wick and most in cervicovaginal lavage samples. The within-subject variation for genital-tract virus level was greater than that for blood. Overall, the odds for viral RNA detection in the genital tract approximately tripled for each 10-fold increase in plasma viral RNA concentration (P<.001) or with concomitant genital tract infection (P=.003). Endocervical canal wicks should be considered as an adjunct to cervicovaginal lavage, to improve the sensitivity and precision of HIV-1 RNA detection.

Cervix Uteri↗
PubMed2001

Delayed hypersensitivity skin testing to mumps and Candida albicans antigens is normal in middle-aged HTLV-I- and-II-infected U.S. cohorts.

It has been reported that human T cell lymphotropic virus (HTLV)-I-infected persons in Japan have decreased delayed hypersensitivity skin test reactivity to tuberculin purified protein derivative (PPD), but HTLV-I- or -II-infected persons do not generally develop opportunistic infections. We administered standardized intradermal testing with PPD, mumps, and Candida albicans antigens to 31 HTLV-I, 48 HTLV-II, and 143 seronegative subjects in the United States. Reactivity at 48 hr was compared among the three groups. Response rates to PPD were very low in all subjects. Fifty-five percent of seronegative subjects did not react to mumps antigen, compared with 55% of HTLV-I [adjusted odds ratio (OR) = 0.79, 95% confidence interval (CI) 0.27-2.33] and 38% of HTLV-II (OR = 0.73, 95% CI 0.33-1.64). Fifty-one percent of seronegatives did not react to Candida albicans antigen, compared with 34% of HTLV-I (OR = 0.37, 95% CI 0.15-0.93) and 46% of HTLV-II (OR = 0.71, 95% CI 0.34-1.52). Anergy was present in 33% of seronegatives, 28% of HTLV-I (OR = 0.60, 95% CI 0.20-1.78), and 19% of HTLV-II (OR = 0.56, 95% CI 0.22-1.44). HTLV-I- and -II-infected persons appear to have intact delayed hypersensitivity skin test responses to mumps and Candida albicans antigens.

Adult↗
PubMed2001

A menstrual cycle pattern for cytokine levels exists in HIV-positive women: implication for HIV vaginal and plasma shedding.

OBJECTIVES: To evaluate the effect of the menstrual cycle in HIV-positive women on plasma and genital cytokine levels, interrelationships between vaginal and plasma cytokines, CD4 and CD8 T cell fluctuations, and genital and plasma viral loads. METHODS: Plasma and cervicovaginal lavage specimens were collected from 55 HIV-positive women with CD4 cell counts < 350 cells/microl during phases of the menstrual cycle. Samples were assayed for IL-1beta, IL-6, IL-4, IL-8, IL-10, TGFbeta, TNFalpha, INFgamma, MIP1alpha, MIP1beta, RANTES, and TNFR-II using enzyme-linked immunosorbent assays. CD4 and CD8 T cell expression was evaluated by flow cytometry. Repeated measures regression models were used to assess the effect of the menstrual cycle on cytokines and viral load. Multivariate repeated regression models were used to assess the correlation among selected cytokines and between selected cytokines and HIV viral load. RESULTS: Vaginal IL-1beta, IL-4, IL-6, IL-8, IL-10, MIP1beta, RANTES, TGFbeta, and TNFR-II were significantly elevated during menses but were not altered during other phases. Plasma cytokine levels were not altered during the menstrual cycle. A positive Candida culture increased vaginal IL-8 during menses, whereas vaginal discharge was associated with a reduction in vaginal IL-4, IL-10, and RANTES. CD4 and CD8 cell numbers did not vary with the menstrual cycle. Vaginal cytokine levels correlated only with vaginal viral load, in a sampling method-dependent manner. CONCLUSION: We provide evidence of elevated vaginal cytokine levels during menses, which appear to regulate vaginal and not plasma HIV shedding, suggesting that a menstrual cycle pattern exists for cytokine production in HIV-positive women impacting vaginal shedding of HIV.

Adolescent↗
PubMed2001

Herpes simplex virus shedding and plasma human immunodeficiency virus RNA levels in coinfected women.

Asymptomatic herpes simplex virus (HSV) shedding was described in a cohort of human immunodeficiency virus (HIV)-infected women, and the association of HSV shedding with changes in plasma HIV RNA load was investigated. Genital, rectal, and oral swabs were obtained daily during a 4-week period for polymerase chain reaction and culture, and concomitant plasma specimens were drawn 3 times weekly for determination of HIV RNA load. During the study, 70% and 79% of subjects shed HSV from the oral cavity and genital area, respectively. Shedding of HSV occurred for a mean of 3.2 days for oral shedding and 5.4 days for genital shedding. Mean plasma HIV RNA loads during periods of HSV shedding and nonshedding and for periods 3 days after the cessation of shedding were compared; no significant differences were found (P=.74). In women who shed HSV, as evaluated by detection of virus, plasma HIV RNA load did not fluctuate with HSV shedding.

Case-Control Studies↗
PubMed2001

Cross-resistance and inheritance of resistance to Bacillus thuringiensis toxin Cry1Ac in diamondback moth (Plutella xylostella L) from lowland Malaysia.

A field population of Plutella xylostella from Malaysia (SERD4) was divided into five sub-populations and four were selected (G2-G5) with the Bacillus thuringiensis insecticidal crystal (Cry) toxins Cry1Ac, Cry1Ab, Cry1Ca and Cry1Da. Bioassay at G6 gave resistance ratios of 88, 5, 2 and 3 for Cry1Ac, Cry1Ab, Cry1Ca and Cry1Da respectively compared with the unselected sub-population (UNSEL-SERD4). The Cry1Ac-selected population showed little cross-resistance to Cry1Ab, Cry1Ca and Cry1Da, (3-, 2- and 3-fold compared with UNSEL-SERD4), whereas the Cry1Ab-SEL sub-population showed marked cross-resistance to Cry1Ac (40-fold), much greater than Cry1Ab itself. In contrast, the Cry1Ca- and Cry1Da-SEL sub-population showed little if any cross-resistance to Cry1Ac and Cry1Ab. The mode of inheritance of resistance to Cry1Ac was examined in Cry1Ac-selected SERD4 by standard reciprocal crosses and back-crosses using a laboratory insecticide-susceptible population (ROTH). Logit regression analysis of F1 reciprocal crosses indicated that resistance to Cry1Ac was inherited as an incompletely dominant trait. At the highest dose of Cry1Ac tested, resistance was recessive, while at the lowest dose it was almost completely dominant. The F2 progeny from a back-cross of F1 progeny with ROTH were tested with a concentration of Cry1Ac that would kill 100% of ROTH. The mortality ranged between 50 and 95% in seven families of back-cross progeny, which indicated that more than one allele on separate loci were responsible for resistance to Cry1Ac.

Animals↗
PubMed2001

Disparate results of ACE inhibitor dosage on exercise capacity in heart failure: a reappraisal of vasodilator therapy and study design.

Despite manifest benefits of angiotensin converting enzyme (ACE) inhibitors on the prognosis of patients with heart failure, there is a lack of consistency in the results of trials investigating the effects of ACE inhibitors on exercise capacity. The inconsistencies cannot be readily explained by variations in effects on known neurohumoral or conventional haemodynamic factors. Drawing on insights from physiology of pump-load interactions, in a normal circulation there is an optimal extent of systemic vasodilation at which the delivery of hydraulic energy from the cardiac pump is maximal (the 'impedance matchpoint'). In heart failure, the vasoconstrictive effects shift the operating point towards mismatch at higher resistances, and optimal vasodilatory therapy would reshift the operating point to the matchpoint. Excessive dosage, however, would cause overvasodilatation leading to a reduction in cardiac power output and consequently compromising exercise ability. High levels of ACE inhibitors may not therefore improve exercise ability. Another potential reason for the observed inconsistencies is that the often used parallel-group study design (ideal for mortality studies) may not be suitable for investigating drug effects on exercise capacity because dropouts from such studies would introduce occult selection biases, thereby confounding treatment effects. In conclusion, this reappraisal of the conflicting observations reported on ACE inhibitor effects on exercise capacity has highlighted a proposition that there is an optimal dosage of ACE inhibitors which will most enhance exercise capacity, and this will require further well designed cross-over studies to elucidate.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed2001

The impact of the pharmacist on an elective general surgery pre-admission clinic.

OBJECTIVE: A traditional clinical pharmacy service for surgical patients involves a ward visit that identifies and responds to issues after prescribing has taken place. It was hypothesised that pharmacist involvement in a general surgery pre-admission clinic (PAC) would provide elective patients with significantly better pharmaceutical care than ward visits alone. METHOD: 100 elective general surgery patients were recruited into 2 groups as part of a non-randomised controlled trial. The groups were comparable in terms of age, surgical procedure and use of medicines. The control group received standard ward visits. The intervention group had pharmaceutical assessment in a pre-admission clinic. This assessment incorporated pharmacist-led drug history taking and prescription transcription. OUTCOME MEASURES: Number, classification and clinical significance of pharmaceutical interventions. RESULTS: A pharmacist made 76 interventions in the PAC group and 79 interventions in the ward group. No prescribing errors and omissions were made in the PAC group. The clinical significance of PAC interventions was rated more highly than ward interventions on two scales. Involvement in the PAC increased the pharmacist's workload, but saved time for surgical and nursing staff. Surgical and nursing staff identified writing discharge prescriptions as the most valuable service provided by the PAC pharmacist. CONCLUSION: By ensuring safe prescribing in the PAC group, the pharmacist was able to become more involved in clinical issues. Pharmacist involvement in PACs presents a useful opportunity for expansion of pharmacy services. However, extra resources would be needed in order to provide these services fully.

Aged↗
PubMed2001

First-time blood donors: demographic trends.

BACKGROUND: With changing demographics of the United States population and the continuous need to recruit new donors, it is important to monitor the demographic profile of first-time donors and to evaluate changes in the donor pool to improve recruitment targeting. STUDY DESIGN AND METHODS: First-time whole blood (n = 901,862) donors at five United States blood centers between 1991 and 1996 were analyzed. RESULTS: The total number of first-time donors appears to be decreasing. Over the 6-year period, there was an overall increase in the proportion of Hispanic and other minority first-time donors and a concurrent decrease in the proportion of white donors at Retrovirus Epidemiology Donor Study centers. Other variables, including age, sex, and education, did not show a consistent trend. CONCLUSION: The demographic profile of first-time donors is changing. These data highlight the importance for blood centers to continuously monitor the donor population. A better understanding of the donor population may help blood centers adjust their donor outreach, recruitment, and retention programs. New recruitment efforts appear needed to counter general apathy toward donating blood, and minority groups appear to be receptive to becoming blood donors.

Blood Donors↗
PubMed2001

Incidence rates of viral infections among repeat donors:are frequent donors safer?

BACKGROUND: Incidence rates (IRs) for viral infections may vary with the frequency of donation among repeat, community, whole-blood (WB) donors, with IRs thought to be lower among donors with higher frequency of donation. STUDY DESIGN AND METHODS: IRs for HIV, HTLV, HCV, and HBV infection were stratified by frequency of donation among 868,403 repeat WB donors who gave approximately 4 million donations at five United States blood centers from 1991 through 96. All donors had given at least 2 donations during those years, with the first donation being nonreactive on confirmatory testing. Frequency of donation was measured in three ways: by the number of donations per year; at the time of donation, by the number of donations given within the preceding 2-year period; and by the number of donations given from 1991 through 1993. RESULTS: The IRs for HIV, HCV, and HBV infection did not appear to differ among donors with lower or higher numbers of donation per year. However, the IR for HTLV infection decreased as the number of donations per year increased (p = 0.0004). IRs for all viral markers remained stable, regardless of the number of donations given within the 2-year period before the donation. Although IRs for HIV, HTLV, and HCV infection did not vary by the number of donations given in 1991 through 1993, the IR for HBV infection appeared to be lower in donors who gave more donations in that period (p = 0.01). CONCLUSION: These findings do not provide evidence of a lower IR for transfusion-transmissible viral infections among repeat WB donors who give more frequently. Abbreviated screening histories for frequent repeat donors might not be advisable.

Adult↗
PubMed2001

Peak exercise cardiac power output; a direct indicator of cardiac function strongly predictive of prognosis in chronic heart failure.

OBJECTIVES: This study assessed the prognostic value of peak cardiac power output, measured non-invasively during maximal cardiopulmonary exercise testing, against other exercise-derived haemodynamic variables in patients with chronic congestive heart failure. METHOD AND RESULTS: Two hundred and nineteen unselected, consecutive patients with congestive heart failure (166 men, mean (+/-SD) age of 56+/-13 years) who underwent maximal symptom limited cardiopulmonary treadmill exercise testing with non-invasive estimation of cardiac output using carbon dioxide re-breathing techniques, were followed-up for a mean period of 4.64 (4.47--4.82, 95% CI) years. Cardiac power output was calculated from the product of cardiac output and mean arterial blood pressure. All cause mortality was 12.3% (27 deaths). Peak and resting cardiac power output, peak mean arterial blood pressure, peak and resting cardiac output and peak VO(2)were all predictive of outcome on univariate analyses. Peak cardiac power output, either entered continuously or categorically with a cut-off value of 1.96 watts, was the only independent predictor of mortality (P=0.0004 for values < or >1.96 watts and P=0.001 for continuous values) using multivariate analysis. A relative risk ratio of 5.08 (1.94-13.3, 95% CI) was obtained for a cardiac power output <1.96 watts. CONCLUSION: Peak cardiac power output is an independent predictor of mortality that can be measured non-invasively using cardiopulmonary exercise testing. It can give further prognostic power to a peak VO(2)in the assessment of patients with congestive heart failure.

Adult↗
PubMed2001

New mutations in pncA of in vitro selected pyrazinamide-resistant strains of Mycobacterium tuberculosis.

Mutations within the pncA gene can cause pyrazinamide (PZA) resistance in Mycobacterium tuberculosis. To study further the mutational events leading to PZA resistance, a H37Rv PZA-susceptible strain was used to derive PZA-resistant mutants in vitro. This parental strain was grown at gradually increased concentrations of PZA (from 200 up to 500 microg/ml). A total of eight variant strains were selected for further study. PZA resistance was selected at 250 microg/ml or higher. Seven of them lost PZase activity and hence were PZA resistant. The remaining strain has shown a functional PZase and hence was sensitive to PZA after being exposed to 200 microg/ml PZA. Sequence analysis shows different novel mutations within the pncA gene of these variants. Two silent mutations at nucleotide 6 (G --> A) and 300 (C --> T) were found in the PZA-sensitive variant. Among the seven PZA-resistant variants, there were three deletion mutations found at nucleotide 78 (G), 79 (A), and 143 (A), all resulting in a frameshift, and one nonsense mutation at nucleotide 102 (C --> G), creating a stop codon TAG. It was observed that the mutations found in the pncA gene of these PZA-resistant mutants show a distinctive pattern: mutation positions moved toward the beginning of the open reading frame correlating with the increase in PZA concentration, suggesting a possible relationship between the increase of PZA concentration and the early occurrence of mutations on the pncA gene.

Amidohydrolases↗
PubMed2001

Hospice nursing: the specialty.

The purpose of this study was to identify and delineate what experienced hospice nurses perceive as the knowledge and skills base essential to their practice of hospice nursing as a specialty. Little of this specialty is taught in basic nursing programs, so another purpose was to determine the methods hospice nurses use for knowledge and skills acquisition. The qualitative study method of focused ethnography was used. This method allowed the researcher to examine hospice nurses in the context of their own community-based agency, enter the research arena with specific questions, describe the topic from the viewpoint of the participants, use multiple data sources, and begin data analysis concurrently with data collection, which continued until saturation was reached. During data analysis, 11 categories emerged. Four of these categories involved skills: (a) assessment skills, (b) communication skills, (c) technical skills, and (d) management skills; and seven categories primarily involved knowledge: (a) end-stage disease process, (b) signs of impending death, (c) palliative therapeutics, (d) collaboration between disciplines, (e) advocacy, (f) philosophy and ethics of hospice care, and (g) family dynamics. Of these 11 categories, the one discussed and observed most often was that of assessment skills. It was found that the hospice nurses learned their specialty by doing it. However, the need for graduate education in hospice nursing became apparent.

Anthropology, Cultural↗
PubMed2001

Assessment of adenosine, arbutamine and dobutamine as pharmacological stress agents during (99m)Tc-tetrofosmin SPECT imaging: a randomized study.

We evaluated the use of adenosine, dobutamine and arbutamine with (99m)Tc-tetrofosmin myocardial perfusion imaging. Forty patients under investigation for suspected coronary artery disease were recruited. Each had a resting scan and two separate stress scans on different days, in a randomized cross-over study. Resultant images were blindly reported in 13 segments per scan as normal, reversible or fixed defects. A score was given (0-3) for segmental defect severity. Haemodynamic responses were as expected for each agent. Subjective side effect scores did not differ overall between agents. Adenosine caused a significantly higher incidence of abnormal taste (54%) than dobutamine and arbutamine (both 23%) and a lower incidence of palpitations (25% vs 69% and 54%, respectively), all P<0.05. Arbutamine caused significantly more chest pain than adenosine (77% vs 46%) though less flushing (35% vs 68%), both P<0.05. Comparison of the results obtained showed highly significant levels of segmental agreement for visual and semi-quantitative analysis between adenosine and arbutamine, kappa value and correlation coefficient of 0.78 and 0.86, respectively, dobutamine and adenosine 0.69 and 0.78, and arbutamine and dobutamine 0.75 and 0.78, all P<0.0001. Adenosine, arbutamine and dobutamine differ in their haemodynamic response and side effect profile but provide highly comparable results during (99m)Tc SPECT imaging.

Adenosine↗
PubMed2001

Variation in susceptibility to Bacillus thuringiensis toxins among unselected strains of Plutella xylostella.

So far, the only insect that has evolved resistance in the field to Bacillus thuringiensis toxins is the diamondback moth (Plutella xylostella). Documentation and analysis of resistant strains rely on comparisons with laboratory strains that have not been exposed to B. thuringiensis toxins. Previously published reports show considerable variation among laboratories in responses of unselected laboratory strains to B. thuringiensis toxins. Because different laboratories have used different unselected strains, such variation could be caused by differences in bioassay methods among laboratories, genetic differences among unselected strains, or both. Here we tested three unselected strains against five B. thuringiensis toxins (Cry1Aa, Cry1Ab, Cry1Ac, Cry1Ca, and Cry1Da) using two bioassay methods. Tests of the LAB-V strain from The Netherlands in different laboratories using different bioassay methods yielded only minor differences in results. In contrast, side-by-side comparisons revealed major genetic differences in susceptibility between strains. Compared with the LAB-V strain, the ROTH strain from England was 17- to 170-fold more susceptible to Cry1Aa and Cry1Ac, respectively, whereas the LAB-PS strain from Hawaii was 8-fold more susceptible to Cry1Ab and 13-fold more susceptible to Cry1Da and did not differ significantly from the LAB-V strain in response to Cry1Aa, Cry1Ac, or Cry1Ca. The relative potencies of toxins were similar among LAB-V, ROTH, and LAB-PS, with Cry1Ab and Cry1Ac being most toxic and Cry1Da being least toxic. Therefore, before choosing a standard reference strain upon which to base comparisons, it is highly advisable to perform an analysis of variation in susceptibility among field and laboratory populations.

Animals↗