Search PubMed⌕ Search

Biomedical subjects

D J Wright

Publications and source records attributed to D J Wright.

At least 55 records · Page 3Linked to original sources
PubMed2001

Cyt1Aa from Bacillus thuringiensis subsp. israelensis is toxic to the diamondback moth, Plutella xylostella, and synergizes the activity of Cry1Ac towards a resistant strain.

The Bacillus thuringiensis subsp. israelensis cytolytic protein Cyt1Aa was found to be toxic to an insecticide-susceptible laboratory population of Plutella xylostella. Cry1Ac-resistant populations of P. xylostella showed various degrees of resistance to Cyt1Aa. Cyt1Aa/Cry1Ac mixtures showed a marked level of synergism in the Cry1Ac-resistant populations.

Animals↗
PubMed2001

Susceptibility of a field-derived, Bacillus thuringiensis-resistant strain of diamondback moth to in vitro-activated Cry1Ac toxin.

Resistant and susceptible populations of the diamondback moth (Plutella xylostella) were tested with crystalline, solubilized, and partially and fully activated forms of the Bacillus thuringiensis Cry1Ac delta-endotoxin. Fully activated toxin greatly reduced the resistance ratio (ratio of the 50% lethal concentration for the resistant population to that for the susceptible population) of the resistant population, suggesting that a defect in toxin activation is a major resistance mechanism.

Animals↗
PubMed2001

Assessment of a low-intensity cardiac rehabilitation programme using the six-minute walk test.

OBJECTIVE: To examine the utility of the six-minute walk test (6'WT), in assessing the effectiveness of a six-week cardiac rehabilitation programme, of which exercise training was an integral part. SETTING: Royal Liverpool and Broad Green Hospitals Rehabilitation Unit. DESIGN: Two hundred and thirty-nine consecutive patients referred for cardiac rehabilitation were allocated to one of two groups. In group A 209 entered and 159 completed the usual rehabilitation programme whilst group B patients (n = 30) acted as a control by deferring entry to the programme for six weeks, continuing only activities of daily living. OUTCOME MEASURES: Both groups were assessed using the 6'WT, peak expiratory flow rate (PEFR) and isometric grip strength at enrolment and six weeks. RESULTS: At baseline, groups A and B were demographically identical without significant differences in terms of 6'WT, PEFR or grip strength. Following the study period, group A showed a significant increase in 6'WT from 314.7 +/- 76.2 to 377.3 +/- 78.6 m, in PEFR from 406.9 +/- 115.9 to 437.8 +/- 118.6 litres per minute and in grip strength from 28.8 +/- 9.31 to 30.3 +/- 8.93 kg, all p < 0.001. There were no significant changes in group B. CONCLUSIONS: The 6'WT proved to be a simple and effective measurement of functional capacity in patients performing cardiac rehabilitation. The clinical programme investigated successfully increased patients' functional capacity as assessed by the 6'WT. Significant improvement in PEFR and grip strength was also demonstrated, compared with a control population.

Aged↗
PubMed2000

Effect of menstrual cycle on HIV-1 levels in the peripheral blood and genital tract. WHS 001 Study Team.

OBJECTIVE: To assess the variation in HIV-1 over the menstrual cycle, including RNA levels in the female genital tract, plasma HIV-1-RNA levels, CD4 cell counts, and culturable virus. DESIGN: A prospective analysis of 55 HIV-1-infected women. METHODS: Blood and genital tract specimens were collected weekly over 8 weeks, spanning two complete menstrual cycles. Applying repeated-measures models that used menses as the reference level, the variation in viral RNA levels was compared in endocervical canal fluid and cells (collected by Sno-strips and cytobrush, respectively) and ectocervicovaginal lavage (CVL) fluid. Repeated-measures models were also used to assess the variation in plasma CD4 cell counts and viral load. RESULTS: Shedding patterns differed among the three sampling methods, independent of genital tract co-infections. Genital tract HIV-1-RNA levels from CVL fluid and endocervical canal cytobrush specimens were highest during menses and lowest immediately thereafter (P = 0.001 and P = 0.04). The HIV-1-RNA level in endocervical canal fluid was highest in the week preceding menses (P = 0.003). The menstrual cycle had no effect on blood levels of RNA (P = 0.62), culturable virus (P = 0.34), or CD4 cell counts (P = 0.55). HIV-1-RNA levels were higher in endocervical canal fluid than in peripheral blood plasma during the late luteal phase (P = 0.03). CONCLUSION: HIV-1-RNA levels vary with the menstrual cycle in the female genital tract but not the blood compartment. HIV-1-RNA levels are higher in endocervical canal fluid than in blood plasma. These findings may have important implications for sex-specific pathogenesis, heterosexual transmission, and contraceptive hormone interventions in HIV-1-infected women.

Adult↗
PubMed2000

Trends in incidence and prevalence of major transfusion-transmissible viral infections in US blood donors, 1991 to 1996. Retrovirus Epidemiology Donor Study (REDS)

CONTEXT: Evaluating trends in blood donor infectious disease rates is essential for monitoring blood supply safety and donor screening effectiveness. OBJECTIVE: To determine changes over time in blood donor population infection rates of human immunodeficiency virus (HIV), human T-lymphotropic virus (HTLV), hepatitis C virus (HCV), and hepatitis B virus (HBV). DESIGN: Cross-sectional survey data from the National Heart, Lung, and Blood Institute-sponsored Retrovirus Epidemiology Donor Study. SETTING: Five blood centers in different regions of the United States. PARTICIPANTS: A total of 1.9 million volunteer blood donors with 1 or more nonautologous donations from January 1991 to December 1996. MAIN OUTCOME MEASURES: Changes in rates of HIV, HTLV, HCV, and HBV infections were evaluated by comparing yearly prevalence estimates (per 100,000 donations) for first-time allogeneic donors and period-specific incidence rates (IRs) (per 100,000 person-years) for repeat allogeneic donors between 1991 and 1996 (for HCV, from about March 1992 to June 1996). RESULTS: Prevalence of HIV decreased in first-time donors from 0.030% to 0.015% (P=.006) and HCV prevalence decreased from 0.63% to 0.40% (P<.001). Trends were not statistically significant for the proportion of first-time donors with hepatitis B surface antigen (HBsAg) or HTLV. For repeat donors, IRs did not change significantly, indicating a stable but low level of seroconversion. The overall IRs (95% confidence intervals) per 100,000 person-years were 2.92 (2.26-3.70) for HIV, 1.59 (1.12-2.19) for HTLV, 3.25 (2.36-4.36) for HCV, and an estimated 10.43 (7.99-13. 37) for HBV (based on an HBsAg rate of 2.66 [2.04-3.41] with presumed false-positive results considered negative). The HBV IR estimate with presumed false-positive results considered positive (for comparability to previous analyses) was 17.83 (14.60-21.56). CONCLUSION: The decrease in HIV and HCV prevalence rates, combined with the previously documented lower rates of infection in first-time donors compared with the general population, suggests the continued benefit of behavioral risk factor screening. JAMA. 2000;284:229-235

Blood Banks↗
PubMed2000

Human factors and cardiac surgery: a multicenter study.

OBJECTIVE: To study the role of human factors on surgical outcomes, with a series of 243 arterial switch operations performed by 21 surgeons taken as a model. METHODS: The following data were collected: patient-specific and procedural variables, self-assessment questionnaires, and a written report from a human factors researcher who observed the operation. The relationship of patient-specific variables to outcomes (death and death and/or near miss) was used to develop a multivariable baseline model to analyze the role of human factors after adjustment for these variables. RESULTS: The overall mortality was 6.6% with 24.3% of cases resulting in death and death and/or near misses. The self-assessment questionnaires were found to be unhelpful. Major and minor human failures were extracted from the written report. Major negative events were potentially life-threatening failures, whereas minor events were failures that, in isolation, were not expected to have serious consequences. Major events were closely related to death (P <.001) and death and/or near misses (P <.001). Appropriate compensation, however, sharply reduced the risk of death (P =.003). The total number of minor events was also closely related to both death and death and/or near misses (P <.001). CONCLUSION: The study highlights the role of human factors in negative surgical outcomes. Even in the most eventful circumstances, however, appropriate human factors defense mechanisms can lead to a successful outcome.

Cardiac Surgical Procedures↗
PubMed2000

The impact of the ovulatory cycle on cytokine production: evaluation of systemic, cervicovaginal, and salivary compartments.

To understand the impact of the menstrual cycle on immunologic parameters, we measured the level of cytokines and chemokines from plasma, cervicovaginal lavage (CVL), and saliva samples of 6 premenopausal women during the follicular and luteal phases of the ovulatory cycle. We demonstrate that the level of plasma interleukin-8 (IL-8) was 4-fold higher during the follicular phase than the luteal phase (p = 0.004), whereas plasma IL-1beta, IL-4, IL-6, IL-10, interferon-gamma (IFN-gamma), transforming growth factor-beta (TGF-beta), tumor necrosis factor-alpha (TNF-alpha), macrophage inflammatory protein-1alpha (MIP-1alpha), and TNF receptor II (TNFR II) were not altered during the ovulatory cycle. In the vaginal compartment, as measured from CVL samples, the levels of IL-6 and IL-1beta were both 5-fold higher in the follicular than the luteal phase (p = 0.0002 and 0.03, respectively). Salivary cytokine and chemokine samples were similar when measured during the luteal and the follicular phases. Additional analysis of lymphocyte subsets for phenotypic and functional markers indicated that they were not influenced by the ovulatory cycle. Collectively, these data suggest that IL-6, IL-8, and IL-1beta are differentially regulated during the ovulatory cycle.

Adolescent↗
PubMed2000

Hormonal levels among HIV-1-seropositive women compared with high-risk HIV-seronegative women during the menstrual cycle. Women's Health Study (WHS) 001 and WHS 001a Study Team.

There is a paucity of normative data on hormonal levels among HIV-infected women. Hormonal levels may influence fertility and HIV-related immunological and virological factors. The objective of this study was to determine progesterone and estradiol levels during the menstrual cycle in HIV-seropositive women compared with high-risk seronegative women. The study enrolled 55 HIV-infected and 10 high-risk uninfected women with self-reported regular menstrual cycles (25-30-day cycles). Progesterone and estradiol levels were determined on a weekly basis for 8 weeks. The analysis included evaluations from the first complete menstrual cycle for the 54 HIV-infected and 9 uninfected women who had at least one complete cycle. The median age was 35 years for HIV-infected women and 36 years for uninfected women. The median CD4+ count for HIV-seropositive women was 210 cells/mm3. The median menstrual cycle length was 28 days (range 22-49 days) for HIV-infected women and 25 days (range 24-44 days) for uninfected women. The maximum progesterone level during the luteal phase was normal (>3.0 ng/ml) for 52 (96%) of 54 HIV-seropositive women and 7 (78%) of 9 HIV-seronegative women (p = 0.09, Fisher's exact test). The median maximum progesterone level was 12.2 ng/ml in HIV-seropositive women and 7.2 ng/ml in HIV-seronegative women (p = 0.07, Wilcoxon test). The median maximum estradiol value during the follicular phase was 148 pg/ml for HIV-seropositive women and 111 pg/ml for HIV-seronegative women (p = 0.04, Wilcoxon test). Among HIV-infected women, there were no significant differences in progesterone and estradiol levels by antiretroviral therapy, baseline plasma viral load, or median CD4+ cell count. We conclude that HIV-infected women with self-reported normal menstrual cycles have normal levels of progesterone and estradiol during the menstrual cycle.

Adult↗
PubMed2000

Genetic and biochemical approach for characterization of resistance to Bacillus thuringiensis toxin Cry1Ac in a field population of the diamondback moth, Plutella xylostella.

Four subpopulations of a Plutella xylostella (L.) strain from Malaysia (F(4) to F(8)) were selected with Bacillus thuringiensis subsp. kurstaki HD-1, Bacillus thuringiensis subsp. aizawai, Cry1Ab, and Cry1Ac, respectively, while a fifth subpopulation was left as unselected (UNSEL-MEL). Bioassays at F(9) found that selection with Cry1Ac, Cry1Ab, B. thuringiensis subsp. kurstaki, and B. thuringiensis subsp. aizawai gave resistance ratios of >95, 10, 7, and 3, respectively, compared with UNSEL-MEL (>10,500, 500, >100, and 26, respectively, compared with a susceptible population, ROTH). Resistance to Cry1Ac, Cry1Ab, B. thuringiensis subsp. kurstaki, and B. thuringiensis subsp. aizawai in UNSEL-MEL declined significantly by F(9). The Cry1Ac-selected population showed very little cross-resistance to Cry1Ab, B. thuringiensis subsp. kurstaki, and B. thuringiensis subsp. aizawai (5-, 1-, and 4-fold compared with UNSEL-MEL), whereas the Cry1Ab-, B. thuringiensis subsp. kurstaki-, and B. thuringiensis subsp. aizawai-selected populations showed high cross-resistance to Cry1Ac (60-, 100-, and 70-fold). The Cry1Ac-selected population was reselected (F(9) to F(13)) to give a resistance ratio of >2,400 compared with UNSEL-MEL. Binding studies with (125)I-labeled Cry1Ab and Cry1Ac revealed complete lack of binding to brush border membrane vesicles prepared from Cry1Ac-selected larvae (F(15)). Binding was also reduced, although less drastically, in the revertant population, which indicates that a modification in the common binding site of these two toxins was involved in the resistance mechanism in the original population. Reciprocal genetic crosses between Cry1Ac-reselected and ROTH insects indicated that resistance was autosomal and showed incomplete dominance. At the highest dose of Cry1Ac tested, resistance was recessive while at the lowest dose it was almost completely dominant. The F(2) progeny from a backcross of F(1) progeny with ROTH was tested with a concentration of Cry1Ac which would kill 100% of ROTH moths. Eight of the 12 families tested had 60 to 90% mortality, which indicated that more than one allele on separate loci was responsible for resistance to Cry1Ac.

Animals↗
PubMed2000

Engineering desiccation tolerance in Escherichia coli.

Recombinant sucrose-6-phosphate synthase (SpsA) was synthesized in Escherichia coli BL21DE3 by using the spsA gene of the cyanobacterium Synechocystis sp. strain PCC 6803. Transformants exhibited a 10,000-fold increase in survival compared to wild-type cells following either freeze-drying, air drying, or desiccation over phosphorus pentoxide. The phase transition temperatures and vibration frequencies (P==O stretch) in phospholipids suggested that sucrose maintained membrane fluidity during cell dehydration.

Cyanobacteria↗
PubMed2000

Active Fe-containing superoxide dismutase and abundant sodF mRNA in Nostoc commune (Cyanobacteria) after years of desiccation.

Active Fe-superoxide dismutase (SodF) was the third most abundant soluble protein in cells of Nostoc commune CHEN/1986 after prolonged (13 years) storage in the desiccated state. Upon rehydration, Fe-containing superoxide disumutase (Fe-SOD) was released and the activity was distributed between rehydrating cells and the extracellular fluid. The 21-kDa Fe-SOD polypeptide was purified, the N terminus was sequenced, and the data were used to isolate sodF from the clonal isolate N. commune DRH1. sodF encodes an open reading frame of 200 codons and is expressed as a monocistronic transcript (of approximately 750 bases) from a region of the genome which includes genes involved in nucleic acid synthesis and repair, including dipyrimidine photolyase (phr) and cytidylate monophosphate kinase (panC). sodF mRNA was abundant and stable in cells after long-term desiccation. Upon rehydration of desiccated cells, there was a turnover of sodF mRNA within 15 min and then a rise in the mRNA pool to control levels (quantity of sodF mRNA in cells in late logarithmic phase of growth) over approximately 24 h. The extensive extracellular polysaccharide (glycan) of N. commune DRH1 generated superoxide radicals upon exposure to UV-A or -B irradiation, and these were scavenged by SOD. Despite demonstrated roles for the glycan in the desiccation tolerance of N. commune, it may in fact be a significant source of damaging free radicals in vivo. It is proposed that the high levels of SodF in N. commune, and release of the enzyme from dried cells upon rehydration, counter the effects of oxidative stress imposed by multiple cycles of desiccation and rehydration during UV-A or -B irradiation in situ.

Amino Acid Sequence↗
PubMed2000

Ability of induced corpora lutea to maintain pregnancy in beef cows.

Experiments were conducted in beef cows without a primary CL, in which pregnancy had been maintained with exogenous progestogen. In preliminary trials, replacement CL induced ipsilateral to the embryo and after, rather than before, d 36 of pregnancy, maintained more pregnancies after withdrawal of exogenous progestogen (13/13 vs 2/6; P < 0.05). In Exp. 1, in cows with replacement CL induced by treatment with hCG on d 28 of pregnancy, treatment with flunixin meglumine on d 31 through 37 did not increase maintenance of pregnancy. Experiment 2 was conducted to evaluate directly the effects of concentrations of PGF2alpha and estradiol-17beta during d 31 through 35 of pregnancy on maintenance of pregnancy by replacement CL induced between d 28 and 31. In cows that maintained pregnancy while progestogen was provided, maintenance of pregnancy after withdrawal of exogenous progestogen tended to be greater with high (5/5) than with low (2/6; P < 0.10) concentrations of PGF2alpha and greater with low (6/7) than with high (2/6; P = 0.10) concentrations of estradiol-17beta. Secretion of progesterone by replacement CL was greater (P < 0.05) in cows with high than in those with low concentrations of PGF2, during d 31 through 35. Prostaglandin F2alpha may facilitate attachment of the bovine embryo (d 30 to 40) in a manner similar to that reported for implantation in other species. Cows that did not form CL in response to hCG on d 28 to 31 responded well when retreated after d 36. Again, maintenance of pregnancy was greater when replacement CL were induced after (9/9) rather than before d 36 (8/16; P < 0.05).

Animals↗
PubMed2000

Laboratory abnormalities in former blood donors seropositive for human T-lymphotropic virus types 1 and 2: a prospective analysis.

CONTEXT: The human T-lymphotropic viruses types 1 and 2 (HTLV-1 and HTLV-2) are highly prevalent among injection drug users in the United States. However, the clinical course of infection has not been well characterized. OBJECTIVE: To understand HTLV-1-and HTLV-2-associated laboratory abnormalities, which may provide insights into their underlying pathophysiology. DESIGN: Cohort study. SETTING: Five US blood centers. PARTICIPANTS: A total of 133 HTLV-1-and 332 HTLV-2-seropositive former blood donors and 717 HTLV-seronegative donors followed up prospectively since 1991. MAIN OUTCOME MEASURES: Selected serum chemistry tests and complete blood cell counts were analyzed at enrollment and approximately 2 years later in participants. Repeated-measures analyses were conducted to evaluate the effect of HTLV infection on laboratory measures. RESULTS: Compared with seronegative subjects, HTLV-1-seropositive subjects had 13% higher creatine kinase (P =.02) and slightly elevated lactate dehydrogenase (P =.03) levels at follow-up. The HTLV-2-seropositive participants had 11% higher absolute lymphocyte counts than seronegative subjects (P =.0001). Infection with HTLV-2 also appeared to be associated with slightly higher hemoglobin levels (P =.03) and hematocrit (P =.03) and with lower albumin levels (P =.01). CONCLUSIONS: These results further our understanding of the biological mechanisms underlying HTLV and suggest that HTLV-associated laboratory changes are unlikely to alter clinical evaluation or counseling of otherwise healthy HTLV-infected subjects.

Blood Banks↗
PubMed2000

Classification and analysis of incidents in complex medical environments.

Risk management in medicine is often seen as lagging behind other safety-critical domains where there has been considerable research into incident causation models. In this article, incident analysis theory and methodology from fields other than medicine are applied to an incident reporting scheme in an Edinburgh Intensive Care Unit. The incident analysis model used emphasizes the importance of latent organizational factors and complex, multilayered incident causation. It also takes the role of cognitive performance-shaping factors into account. This provides an analytical framework that integrates the identification of distal causal factors and a mechanism for comparing alternative causal hypotheses.

Intensive Care Units↗