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Biomedical subjects

W Green

Publications and source records attributed to W Green.

At least 19 recordsLinked to original sources
PubMed1995

The effect of changes in house dust mite allergen exposure on the severity of asthma.

To measure the association between changes in house dust mite (HDM) allergen Der p I exposure and changes in the severity of asthma, we re-analysed data from a clinical trial in which 34 HDM-allergic subjects with asthma (18 women, mean age 35 years) were followed for between 3 and 12 months. The concentration of Der p I in fine dust from the bed, the bedroom floor and the living room floor was measured at 3-monthly intervals along with assessment of subjects' spirometric function and airway hyperresponsiveness (AHR, measured by histamine inhalation test). Daily symptom scores, morning peak expiratory flow rate and peak flow variability were measured throughout the study period. The mean Der p I concentration in the bed at baseline was 25.4 micrograms/g (95% CI: 15.8-40.6). During the course of the study large within-subject fluctuations were observed in allergen concentrations and in the measurements of the severity of asthma. Changes in allergen concentration in the bed were significantly correlated with changes in AHR (P = 0.003) and symptom score (P = 0.04). Changes in allergen concentration in the living room floor were correlated with changes in symptom scores (P = 0.01). Although these correlations were significant the magnitude of the effect was relatively modest. We conclude that a large reduction in HDM allergen concentration, particularly in the bed, results in a modest reduction in AHR and improvement in symptoms in HDM-allergic subjects with asthma.

Adolescent↗
PubMed1994

House dust mite allergen avoidance: a randomized controlled trial of surface chemical treatment and encasement of bedding.

To test the effectiveness of a house dust mite (HDM) allergen avoidance strategy we conducted a randomized controlled trial in 35 atopic subjects with asthma, aged 13 to 60 living in Sydney - a high HDM allergen environment. After a 3 month run-in period, subjects were randomized to active allergen avoidance treatment (n = 17) or placebo (n = 18) groups and followed for 6 months. The active treatment involved placing impermeable covers over the mattress, pillows and duvet and spraying the remaining bedding, as well as the carpets and furniture, with a tannic acid/acaricidal spray. Subjects kept a daily record of symptoms and peak expiratory flow rates and had 3 monthly assessments of lung function and airway hyperresponsiveness (AHR). Dust samples were collected from the bed, the bedroom floor and the living room floor at 3 monthly intervals and 2 weeks after the treatment. Mean HDM allergen levels at baseline at these sites were, in the active group, 15.5, 9.6 and 10.2 micrograms Der p I/g of fine dust, and, in the placebo group 25.7, 11.8 and 6.3 micrograms/g. Two weeks after the allergen avoidance treatment the HDM allergen level in the beds was reduced to 29% of baseline (95% CI 16-50%, P = 0.038 compared with placebo), but was not significantly different at 3 or 6 months. There was also no significant effect of the allergen avoidance treatment on symptom scores, peak flow variability, lung function or AHR P > 0.1).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1994

Distribution of cytokine proteins within epiretinal membranes in proliferative vitreoretinopathy.

This study reports on the immunohistochemical staining for cytokine proteins of 26 epiretinal membranes obtained from eyes undergoing surgery for the treatment of proliferative vitreoretinopathy. All specimens were investigated for the distribution of staining for interleukin-1 alpha (IL-1 alpha), interleukin-1 beta (IL-1 beta), interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF alpha), interferon-gamma (IFN gamma) and interleukin-2 (IL-2). The results showed that 22 of the membranes (85%) stained for TNF alpha not only intracellularly but also in the extracellular matrix. This contrasts with the findings that only 2 membranes stained for IL-1 alpha and that another 3 were positive for IL-1 beta. Staining for the cytokines IL-6 and IFN gamma was also observed in 9 and 7 membranes respectively. None of the specimens investigated stained with antibodies to IL-2 or control antibodies, and none of three normal retinas stained with any of the antibodies used. Pre-absorption of anti-cytokine antibodies with the corresponding human recombinant cytokines abolished staining of cells and extracellular matrix. The present findings support growing evidence that cytokine-mediated pathways of inflammation are involved in the pathogenesis of proliferative vitreoretinopathy, and draw attention to the possibility that interaction between extracellular matrix-bound cytokine and inflammatory leucocytes or resident cells of the retina may promote the development and perpetuation of this condition.

Antibodies, Monoclonal↗
PubMed1992

T-lymphocyte proliferation: tyrosine kinases in interleukin 2 signal transduction.

Interleukin 2 (IL-2)-induced tyrosine phosphorylation appears to play a major role in IL-2-induced cellular proliferation. Several intracellular substrates including the beta chain of the IL-2 receptor complex (IL-2R beta), raf, MAP2 kinase, the regulatory 83 kDa subunit of phosphatidylinositol-3 kinase and S6 kinases are substrates for the IL-2 receptor activated kinase(s). However, none of the identified members of the IL-2 receptor complex exhibits intrinsic tyrosine kinase activity. Therefore, the IL-2R complex must activate intracellular tyrosine kinases. We have demonstrated that specific tyrosine and serine/threonine kinases are coprecipitated with IL-2 receptor constructs that mediate IL-2-induced cell proliferation but not with those that do not. The IL-2-activated tyrosine kinase appears to be associated with a serine and proline rich intracellular domain which is highly conserved between IL-2R beta and the erythropoietin receptor. Although the responsible kinase has not been identified, lck, fyn, fgr, ltk, hck and lyn can be ruled out as obligatory mediators. Using methods to clone tyrosine kinases from T cells, we have identified potential candidate kinases, including several which had not been known to be expressed by T lymphocytes as well as several unique kinases which had not been previously identified in any cell type.

Amino Acid Sequence↗
PubMed1992

Autopsy findings in HIV-infected inner-city patients.

To assess the importance of the autopsy in HIV-1 infection, we retrospectively reviewed the autopsy reports of 70 HIV-1-seropositive patients at Howard University Hospital. Of the 58 patients with AIDS, the diagnosis of AIDS was made after autopsy in 24 (41%) cases. The lung was the most common site of AIDS-diagnostic diseases, and was affected in 90% of patients. Pneumocystis carinii infection was the most common AIDS-diagnostic disease, and was present in 50% of the AIDS patients. Thirty-eight percent of AIDS diagnostic diseases were diagnosed antemortem, including 15 of the 29 Pneumocystis carinii infections. Most of the AIDS-diagnostic diseases were disseminated at autopsy and two or more diseases were found in some organs. Overall, Pneumocystis carinii pneumonia was the most common cause of death, accounting for a mortality of 43% among AIDS patients. Bacterial infections were common and contributed to the mortality and morbidity of both AIDS and non-AIDS patients. Bacterial infection was the cause of death in 15 AIDS and 9 non-AIDS patients. The clinical cause of death concurred with the pathological cause in 53% of our cases.

Adult↗
PubMed1991

Hemodialysis with cuprophane membrane modulates interleukin-2 receptor expression.

Chronic dialysis patients have several indices of immune deficiency. We examined the hypothesis that the biocompatibility of dialysis membranes may influence the ability of lymphocytes to express interleukin-2 (IL-2) receptors on their surface, a key event in cellular immune response. We investigated the potential role of the dialysis membrane in eight chronic hemodialysis patients. The study design was a cross-over study using cuprophane and polymethylmethacrylate (PMMA) membranes. Chronic dialysis with new cuprophane membrane leads to an increase in baseline expression of the two subunits of IL-2 receptors. IL2R alpha (p55, CD25) and IL-2R beta (p70), in peripheral blood mononuclear cell (PBMC). However, Phytohemagglutinin (PHA) stimulation of PBMC harvested after two weeks of dialysis with cuprophane membrane showed a markedly decreased expression of high affinity IL-2 receptors. These findings are reversed when patients were dialyzed with a PMMA membrane which is also associated with minimal complement activation. The increased expression of IL-2 receptor subunits are reproduced in vitro by direct contact of PBMC with cuprophane membrane and by the addition of the anaphylatoxin C5a. This study confirms the participation of lymphocytes in the complex blood-membrane interactions that occurs during dialysis; the results may be relevant to observations of immune deficiency in dialysis patients.

Aged↗
PubMed1990

Oral intubation in the multiply injured patient: the risk of exacerbating spinal cord damage.

The use of oral intubation during the resuscitation of seriously injured patients has been discouraged because of the fear that this technique may lead to cervical cord damage. We report a retrospective study of the 18-month experience of an emergency department in which oral intubation was the usual method of airway control for victims of blunt trauma. There were 237 injured patients intubated in the ED; 21 patients (8.9%) had cervical cord or bone injury. There were no patients in whom a neurologic loss followed an airway maneuver. Oral intubation was the definitive airway maneuver in 213 patients. There was no statistically significant difference in the type of definitive airway maneuver used (eg, oral intubation, nasal intubation, or cricothyrotomy-tracheotomy) between patients with cervical injuries and patients without such injuries. The risk of spinal cord injury secondary to oral intubation in the seriously injured patient was low in our population. Selection of the method for definitive airway control should be based primarily on the operator's skills and experience rather than the fear of inflicting cervical cord damage.

Adult↗
PubMed1989

Evidence for thyroid hormone deficiency in iron-deficient anemic rats.

Iron-deficient anemic rats have previously been shown to have low plasma levels of thyroid hormone and a poor plasma thyroid hormone response to acute cold exposure. As an initial exploration, we examined thyroid hormone metabolism during iron deficiency in age-matched rats from three aspects: 1) plasma TSH (thyrotropin, thyroid stimulating hormone), T4 (thyroxine) and T3 (triiodothyronine) responses to graded doses of exogenous TRH (thyrotropin releasing hormone), 2) plasma T3 kinetics, and 3) rates of hepatic T3 production. Iron-deficient anemic rats had lower basal TSH values and blunted TSH responses to intravenous TRH injection at three different doses (10, 25 and 50 ng TRH/100 g body wt). Iron-deficient anemic rats also had a significant decrease in plasma T3 turnover (42 vs. 88 ng/h in controls), and significantly lower hepatic T4-5'-deiodinase activities than controls [26 vs. 44.0 ng T3/(mg protein.20 min)]. Thus, decreased rates of T3 production in iron-deficient anemic rats, as documented by turnover studies, may be related to decreased deiodinase activity and reduced peripheral formation of T3. The dampened TSH responses to TRH further facilitate or perpetuate this T3 deficiency. We propose that this abnormal thyroid state is partially responsible for impaired thermogenesis in iron-deficiency anemia.

Anemia, Hypochromic↗
PubMed1989

Asthma and chronic airflow limitation in the highlands of Papua New Guinea: low prevalence of asthma in the Asaro Valley.

The prevalence of asthma in the South Fore region of Papua New Guinea was found to be 7.3%, which is thought exceptionally high for highland areas in this country. To investigate the prevalence of asthma and of chronic airflow limitation in a different highland region with similar living conditions, adults and children from 7 villages in the Asaro Valley were interviewed. Questions were asked about smoking history and about past and present symptoms of cough, of shortness of breath, of chest tightness and of asthma. Of 743 adults interviewed, 206 underwent a clinical study with measurements of lung function, bronchial responsiveness and skin prick tests. Dust was collected from the floors and blankets of 36 houses for counts of house dust mites. We did not find any children with symptoms of asthma. Only 2 adults (0.3%) had symptoms consistent with asthma, and a further 6.2% had symptoms and/or lung function consistent with chronic airflow limitation. Most bronchial hyperresponsiveness was associated with asthma or with chronic airflow limitation. The prevalence of atopy was similar in the Asaro and South Fore populations, but the South Fore had higher house dust mite counts in blanket dust. The low prevalence of asthma in the Asaro Valley is unexplained in terms of factors normally associated with asthma. Because asthma in this area does not appear in childhood and only develops in a small proportion of adults, it may be of different aetiology to asthma in Caucasian populations.

Adult↗