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Biomedical subjects

L J Wright

Publications and source records attributed to L J Wright.

At least 19 recordsLinked to original sources
PubMed2004

Application of TAML catalysts to remove colour from pulp and paper mill effluents.

A TAML catalyst (0.5 microM, 0.23 mg/L of effluent) combined with hydrogen peroxide (6.5 mM, 0.19 g/L of effluent) were capable of permanently removing 46% of the colour from bleach plant effluent (Eop, pine-derived) in one hour at 5,000 L effluent per day. Increasing concentrations to 2 microM catalyst (0.9 mg/L of effluent) and 22 mM peroxide (0.75 g/L of effluent), resulted in removal of 78% of the colour. In addition, 29% of the chlorinated organic material (AOX) was also removed. A laboratory investigation indicated that the oxidative process predominantly removed phenolic structures. The low aromatic content of the effluent meant that the majority of the organic material was not substantially altered during treatment. Thus chemical oxygen demand was essentially unchanged. This technology was able to remediate colour from effluents derived from both softwood (pine) and hardwood (eucalypt). Laboratory studies on catalyst life-time during effluent treatment, demonstrated that activity was maintained for a sufficient period to eliminate all the chromophore available to the active species, but that the catalyst did not survive long enough to be discharged into the receiving environment. Microtox tests showed that catalyst degradation products were not toxic to the receiving environment.

Catalysis↗
PubMed2002

An audit of Territorial Army Medical Grades on presentation for mobilisation and full time reserve service at RTMC Chilwell.

An audit was carried out on a cohort of Territorial Army (TA) personnel passing through RTMC in order to assess the quality of their previous medical assessments compared to that undertaken at the time of their mobilisation. The results confirmed the high downgrading rate (18%) amongst TA personnel compared to previous studies that identified grading error rates of 6-6.5% amongst Regular Army personnel. Errors in the entry medical assessments for TA personnel were also identified in nearly half (44%) of records examined. Possible solutions are identified through improved education of examining medical officers and by increasing the pre-deployment time available to obtain specialist referrals. A case is also made for having improved access to previous medical information, both to improve the quality of the pre-deployment medical screening and to ensure appropriate continuity of care for deployed TA personnel.

Adult↗
PubMed1998

Optimal recovery of cytomegalovirus from urine as a function of specimen preparation.

Cytomegalovirus (CMV) is a significant pathogen among immunocompromised patients. We compared supernatant and sediment fractions of centrifuged urine for the optimal recovery of CMV by shell vial culture and polymerase chain reaction (PCR). Of 336 urine specimens, 31 (9.23%) were positive by shell vial culture; of these 29 (93.5%) were identified using the sediment fraction and 17 (54.8%) using the supernatant fraction (p = 0.001, chi2). Of the 29 positive sediment fraction specimens, 24 (82.8%) were identified as CMV positive at 24 h and 5 (17.2%) were identified as positive at 48 h. Two (0.064%) of the total 31 positive specimens were lost to microbial contamination in the sediment inoculated cultures. Of the 17 supernatant fraction specimens, 9 (53.9%) were identified as CMV positive at 24 h and 8 (47.1%) were identified as positive at 48 h. Fourteen (45.2%) of the total 31 positive specimens were lost to either toxicity or microbial contamination in the sediment-inoculated cultures. Thirty-four CMV culture-positive specimens were tested by PCR; 5 of these specimens (14.7%) were PCR negative for both sediment and supernatant fractions; 26 (76.5%) were found to be positive using the sediment fraction and negative using the supernatant; 3 (8.8%) were PCR positive for both the sediment and the supernatant. None of the 34 was identified as positive using the supernatant fraction only (p = 0.001, chi2). These findings demonstrate that the method of specimen preparation can significantly affect the outcome of diagnostic testing for CMV from urine specimens.

Antigens, Viral↗
PubMed1997

Delayed xenograft rejection of pig-to-baboon cardiac transplants after cobra venom factor therapy.

BACKGROUND: This study sought to (i) investigate the efficacy of cobra venom factor (CVF) in preventing hyperacute rejection (HAR) after pig-to-baboon heart transplantation, (ii) examine the effect of additional splenectomy (Spx) and pharmacologic immunosuppression (IS), and (iii) study delayed graft rejection when HAR is avoided by complement depletion. METHODS: Eleven recipient baboons received heterotopic pig heart transplants. Three received either no therapy or IS (cyclosporine + methylprednisolone +/- cyclophosphamide +/- methotrexate) at clinically well-tolerated doses, with graft survival for only 40, 32, and 15 min, respectively. Two received CVF+/-Spx, which extended survival to 5 and 6 days, respectively. Six underwent Spx + CVF therapy + IS; graft survival was 3 hr (technical complication), 6 days (death from sepsis), 10, 12, and 22 days (vascular rejection), and <25 days (euthanized for viral pneumonia with a functioning graft that showed histopathologic features of vascular rejection). RESULTS: Dense deposition of IgM and, to a lesser extent, IgG and IgA were seen on the endothelial cells within 1 hr of transplantation, but only trace levels of complement deposition were present in CVF-treated recipients. Within approximately 5-12 days, cardiac xenografts showed progressive infiltration by mononuclear cells, consisting primarily of activated macrophages producing tumor necrosis factor-alpha and small numbers of natural killer cells; T and B cells were absent. CONCLUSIONS: We conclude that (i) CVF prevents HAR, (ii) the addition of Spx + IS delays rejection, but (iii) the early deposition of antibody leads to progressive graft injury, resulting in (iv) delayed vascular rejection. Our findings indicate that the features of delayed xenograft rejection described in small animal models also occur in the pig-to-baboon model, and that rejection may occur in a complement-independent manner from the effects of antibody and/or host macrophages.

Acute Disease↗
PubMed1995

Specimen type as a source of variability in the reproducibility and timing of cytomegalovirus identification by culture.

Cytomegalovirus (CMV) is a significant contributor to morbidity and mortality among immunocompromised individuals; therefore, rapid and accurate diagnosis is essential. We compared positive cultures (n = 147) from different specimen types as to (a) the incubation time to a positive result and (b) the reproducibility of positive findings in replicate cultures. Five replicate shell vials were inoculated from each specimen: Two vials were stained at 24 h, two at 48 h, and one held and observed for a maximum of 30 days. Positive cultures from tissue biopsy specimens required the shortest incubation (mean = 1.9 days) and urine specimens the longest (mean = 3.9 days) (P < .005). Tissue biopsy specimens were the most reproducible (48.4% of specimens were positive in five of five replicates) and urine specimens the least (no specimens were positive in five of five replicate vials) (P < = .0002). The observed interspecimen variability is important because failure to understand and adjust for these differences could negatively influence the ability to identify CMV in culture.

Culture Media↗
PubMed1994

Measles immunity in employees of a multihospital healthcare provider.

OBJECTIVE: To assess the potential for nosocomial measles transmission by measuring seropositivity among healthcare workers in Utah. DESIGN: Blood specimens were collected for measurement of measles IgG antibody by enzyme immunoassay (EIA). Individuals with undetectable or equivocal antibody levels were considered at risk for infection. Employees were grouped according to the decade of their birth, and analyses of serological findings were done by the Mantel-Haenszel chi-square test for trend. SETTING: The study was performed in a healthcare organization comprised of six urban and 10 rural hospitals. PARTICIPANTS: Employees (n = 5825) were tested regardless of age, history of disease, or immunization. RESULTS: There were 599 employees (10.3%) who were nonimmune. A trend showing age-related differences in immunity was not noted among employees born prior to 1957 (4.7% nonimmune). However, for employees born after that time, there was a significant age-associated increase in the percentage of susceptible individuals (P = 0.00001). The rate of susceptibility was 8.1% for individuals born between 1957 and 1959, 16.3% for individuals born during the 1960s, and 33.7% for those born in the 1970s. CONCLUSIONS: We concluded that employees born after 1960 represent a material risk for transmission of measles in the hospital setting. Despite the low percentage of susceptibility among those born before 1957, the 144 susceptible individuals in this group also are at risk for measles transmission. Thus, during periods of increased measles prevalence, we would recommend screening all healthcare workers regardless of age and vaccinating those who are susceptible.

Adolescent↗
PubMed1992

Immunofluorescent localization of pig complement component 3, regardless of the presence or absence of detectable immunoglobulins, in hyperacutely rejected heart xenografts.

Rabbit heart xenografts transplanted into the neck of newborn pigs were all hyperacutely rejected within two hours regardless of the presence or absence of detectable endogenous immunoglobulins (Ig). Cryostat tissue sections were prepared from the rejected rabbit hearts and incubated with sheep polyclonal antibodies against pig complement component 3 (C3), pig IgG and pig IgM. Specific immunoreaction was visualized by fluorescein-conjugated antibodies to sheep IgG. C3 was localized mainly on the surfaces of vascular endothelial as well as myocardial cells, and the localization was not dependent upon the presence of pig immunoglobulins within the same tissue. Both pig IgG and IgM were detected only in the heart xenografts transplanted into suckled pigs, whereas no trace of immunoglobulin was found in those transplanted into circulating antibody-free presuckled pigs. Treatment with cobra venom factor (which inhibits complement activity) prior to transplantation prolonged xenograft survival and completely abolished C3 immunostaining. The results provide new evidence at the histochemical level that the alternative pathway of complement is involved in hyperacute xenograft rejection of the species combination (rabbit to pig) used in this study.

Animals↗
PubMed1992

Discordant xenograft rejection in an antibody-free model.

Newborn pigs prevented from suckling colostrum were shown to have less than 0.05 micrograms/ml total immunoglobulin present in their serum. Rabbit heart xenografts transplanted heterotopically into the neck of such pigs were hyperacutely rejected, with a mean survival time of 92 +/- 14 min (mean +/- SD). Pigs which had been allowed to suckle and whose serum contained 10-15 mg/ml maternal immunoglobulin hyperacutely rejected rabbit heart xenografts in 109 +/- 62 min. Histological studies showed no Ig binding but complement component 3 (C3) binding to rabbit hearts placed in immunoglobulin-negative pigs. Prolongation of rabbit heart xenograft survival was achieved by administering cobra venom factor (1 mg/kg) to the pigs pretransplant. These data show hyperacute xenograft rejection in the absence of antibody and suggest that its cause is activation of complement by the alternative pathway.

Animals↗
PubMed1991

Presence of human chromosome 1 with expression of human decay-accelerating factor (DAF) prevents lysis of mouse/human hybrid cells by human complement.

Xenogeneic organs transplanted to phylogenetically distant species are subject to rapid destruction mediated by complement. In humans, the complement activation is regulated by several proteins encoded by a series of closely linked genes (RCA locus) located on chromosome 1. The mouse/human hybrid cell line B10 was found to have retained human chromosome 1. FACS analysis confirmed that RCA products such as decay-accelerating factor (DAF) were expressed on the membrane surface of B10 cells. When exposed to human or rabbit complement in the presence of 'naturally occurring' human anti-mouse antibodies these cells were not lysed by human complement but were killed by rabbit complement. This effect could be abrogated by addition of anti-DAF monoclonal antibody (IC6). The results offer potential for genetic manipulation of the human complement regulatory products in animals to overcome xenograft hyperacute rejection.

Animals↗
PubMed1990

Review of the teaching of medical ethics in London medical schools.

The study examined the influence of the Pond Report on the teaching of medical ethics in the London medical schools. A questionnaire was given to both medical students and college officers. All medical colleges reported that ethics was included in the curriculum. However, from students' replies, it seems that attendance of optional courses is low and that not all current final year medical students have had any formal teaching in medical ethics. Stronger guidelines are necessary to ensure appropriate ethical training in London medical schools.

Curriculum↗