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Biomedical subjects

J Raven

Publications and source records attributed to J Raven.

30 records · Page 2Linked to original sources
PubMed1997

Absence of genetic linkage of chromosome 5q31 with asthma and atopy in the general population.

BACKGROUND: Clinical asthma is associated with increased serum total immunoglobulin E (IgE), atopy (skin prick test positivity to common aeroallergens), and bronchial hyperreactivity (BHR) to non-specific stimuli (positive methacholine challenge test). A region on chromosome 5q31-33 has been linked with increased total serum IgE and BHR. A study of the genetic linkage of this region with clinical asthma and atopy was therefore undertaken. METHODS: A polymorphic microsatellite marker in chromosome 5q31 (D5S399) was studied in 119 sibling pairs recruited from the general population who shared asthma, atopy, and/or BHR. Based on our population distribution of 13 different alleles, it was expected that by chance alone sibling pairs would share on average 1.24 alleles and that a significant excess would indicate genetic linkage. RESULTS: No evidence of linkage was found in 45 siblings concordant for asthma (shared alleles = 1.09, p = 0.95), in 103 sibling pairs with atopy (shared alleles = 1.18, p = 0.82), in 51 sibling pairs with BHR (shared alleles = 1.22, p = 0.62), or in 68 sibling pairs who shared atopy in the absence of BHR (shared alleles = 1.22, p = 0.61). A slight non-significant excess of shared alleles (1.44, p = 0.11) was observed in siblings who shared BHR without atopy. CONCLUSIONS: No evidence of genetic linkage of chromosome 5q31 with either clinical asthma or atopy was therefore detected in the population studied. Linkage between chromosome 5q and BHR needs further investigation.

Adult↗
PubMed1997

The effects on asthmatics of exposure to a conventional water-based and a volatile organic compound-free paint.

The water-based paints now frequently used for house painting still contain small amounts of volatile organic compounds (VOCs), with the potential to exacerbate symptoms of asthma. Because of these potential problems and environmental concerns, some manufacturers have produced paints with no VOC content. We wished to compare the effects on asthmatics of conventional water-based paint and the new VOC-free paint. Seventeen asthmatics were recruited on the basis of having previously reported exacerbation of symptoms by paint or other odours. Each undertook a standard painting task with identically coloured conventional acrylic and VOC-free paints in a double-blind, crossover study. Respiratory symptoms, lung function, and airway responsiveness were measured at each visit. A significant increase in reported "wheeze" was detected during use of conventional paint (p<0.01), but not with the new paint. There was also a significantly greater increase in reported "breathlessness" whilst using conventional paint than with the new paint (p<0.05). In contrast, lung function measurements showed a small but significant increase during the use of both paints (p<0.05). There was no significant change in airway responsiveness after use of either paint. The new paint appears to be less likely to cause a worsening of respiratory symptoms than conventional acrylic paint, although this difference is not reflected in measurements of lung function or airway responsiveness. Although the benefit conferred in the majority of asthmatics is probably modest, there may be some patients with an increased sensitivity to paint odour, who would derive a useful symptomatic benefit from using the VOC-free paint.

Adult↗
PubMed1996

Risk factors for asthma among young adults in Melbourne, Australia.

Asthma is more prevalent in Australia than in Europe or North America. As part of the European Community Respiratory Health Survey (ECRHS), we investigated exposure to risk factors for asthma among young adults in Melbourne. During this study, 553 randomly selected and 204 symptomatic participants aged between 20 and 44 years completed a detailed respiratory questionnaire, of whom 675 underwent measurement of bronchial hyperreactivity (BHR) by methacholine challenge and 745 had skin prick tests for atopy. Current asthma, defined as BHR and wheeze in the preceding 12 months, was present in 25.5% of those tested. A family history of asthma was a risk factor for current asthma (maternal asthma odds ratio [OR] 2.4, paternal asthma OR 2.1). Current smokers were 1.7 times more likely to have current asthma. A serious respiratory infection before 5 years of age increased the risk of current asthma 2.3-fold. Atopy on skin testing was also strongly associated with current asthma (OR 5.9). The greatest risks were associated with positive skin tests to Cladosporium, house dust mite, cat and rye grass pollen. We conclude that female gender, maternal asthma, smoking, hayfever, early respiratory infection, occupational exposure and atopy are important risk factors for asthma in young adults.

Adult↗
PubMed1995

Linkage of high-affinity IgE receptor gene with bronchial hyperreactivity, even in absence of atopy.

Asthma is a manifestation of bronchial hyperreactivity (BHR) and forms part of the spectrum of atopic disease. Some pedigree studies of atopy have suggested linkage with the high-affinity IgE receptor (Fc epsilon RI beta) gene on chromosome 11q13, but others find no linkage. The molecular genetics of asthma and BHR have not been studied in the general population. We examined the genetic linkage of the Fc epsilon RI beta gene with clinical asthma and the underlying phenotypes of BHR (to methacholine) and atopy (defined by skinprick testing) in 123 affected sibling-pairs recruited from the general population. We found evidence of significant linkage of a highly polymorphic microsatellite marker in the fifth intron of the Fc epsilon RI beta gene to a diagnosis of asthma (18.0% excess of shared alleles, p = 0.002) and to BHR (21.7% excess of shared alleles, p = 0.001). Significant linkage was also observed in siblings sharing BHR when those with atopy were excluded (32.8% excess of shared alleles, p = 0.004). Atopy in the absence of BHR did not show significant linkage to the Fc epsilon RI beta gene (7.2% excess of shared alleles, p = 0.124). These findings suggest that mutations in the Fc epsilon RI beta gene or a closely linked gene influence the BHR underlying asthma, even in the absence of atopy.

Adult↗
PubMed1995

Gender differences in lung growth.

Annual measurements of lung volumes and forced expiratory flows were made in 281 boys and girls from 8 to 12 years and in another cohort of 287 from 12 to 20 years to measure longitudinal lung growth. Gender differences in growth of lung function were documented, with girls generating greater volume-standardized maximal expiratory flows until age 18.5 years. Beyond that age boys generated higher expiratory flows in proportion to total lung capacity (TLC). There was a time lag of up to 1 year between the age of peak growth velocity in lung volume and peak growth velocity in height. Age at peak growth in flow lagged another year behind that in volume. This was noted more in boys than girls. Dysanaptic lung growth was found with differing rates of growth of maximal expiratory flow compared with TLC or vital capacity (VC).

Adolescent↗
PubMed1992

The influence of the stomach on crop function and feeding behavior in domestic turkeys.

We tested the hypotheses that motility of the crop and muscular stomach are coordinated and that the stomach exerts primary control over crop filling and emptying in domestic turkeys. Simultaneous recordings of motility of the crop, esophagus, and stomach with implanted strain gauge transducers and visual observations of food passage using image intensification radiography revealed an inverse relationship between the frequency of stomach and crop contractions. Artificially filling the stomach of a fasted turkey with a food slurry prior to feeding did not increase crop filling during the first morning meal, but it did inhibit crop emptying in fasted turkeys by markedly reducing the number of crop contractions. Artificially filling the crop of fasted turkeys prior to the first morning meal did not decrease the amount of feeding activity or the total amount of food consumed during that meal. It is suggested that meal termination is associated with the degree of inhibition of esophageal peristalsis.

Animals↗
PubMed1991

Outcome to 8 years of infants less than 1000 g birthweight: relationship with neonatal ventilator and oxygen therapy.

The study involved a cohort of 59 consecutive survivors with birthweights less than 1000 g, born between 1977 and 1980, to 8 years of age. The aim of the report was to determine if those survivors who had received more oxygen and ventilator therapy differed in their outcome compared with those who had received less oxygen and ventilation. Children were graded into four groups, characterized by decreasing durations of oxygen and ventilation. Children who had received less oxygen and ventilation were more likely to be below the third percentile for weight at 2, 5 and 8 years but the trends were significant only at 2 and 5 years (P = 0.006, P = 0.013 and P = 0.19 respectively). The rate of cerebral palsy was 8% at 8 years; the only children with severe or moderate disabilities from their cerebral palsy were in the lowest oxygen and ventilation group (n = 4, P less than 0.02). The frequency of hospital re-admission and the duration of re-hospitalization did not vary significantly between the four groups at any age. The rates of recurrent wheezing episodes or asthma did not vary significantly between the groups. Although the cohort as a whole had some impairment of lung function compared with healthy full-term controls, there was no significant difference between the four groups. Contrary to expectations, our findings suggest lower rates of poor growth and adverse neurological outcomes with increasing durations of oxygen and ventilation in the newborn period.

Birth Weight↗
PubMed1988

Relation of armspan to height and the prediction of lung function.

Height and armspan were measured in healthy 8-18 year old boys and girls to assess the appropriate correction factor to be applied when height cannot be measured easily. No correction factor was found necessary, height being directly estimated from armspan.

Adolescent↗
PubMed1988

Childhood asthma and adult lung function.

An age-matched group of 247 subjects who had had asthma as children and 39 control subjects were studied with lung function and bronchial reactivity testing at the age of 28 years. Lung function of those who had ceased wheezing was essentially normal, but lung function was increasingly abnormal in those who continued to wheeze. Those with frequent wheezing at 28 demonstrated a greater decline in their respiratory function since the age of 7 years than the other groups. Methacholine provocation testing was performed in 91% of the group and was associated with frequency of wheezing and evidence of small airways obstruction. No association was found between reactivity and loss of ventilatory capacity since 21 years of age.

Adult↗
PubMed1977

Glutamate transport driven by an electrochemical gradient of sodium ions in Escherichia coli.

The role of Na+ in glutamate transport was studied in Escherichia coli B, strain 29-78, which possesses a very high activity of glutamate transport (L. Frank and I. Hopkins, J. Bacteriol., 1969). Energy-depleted cells were exposed to radioactive glutamate in the presence of a sodium gradient, a membrane potential, or both. One hundred- to 200-fold accumulation of the amino acid was attained in the presence of both electrical and chemical driving forces for the sodium ion. Somewhat lower accumulation values were obtained when either chemical or electrical driving forces were applied separately. A chemical driving force was produced by the addition of external Na+ to Na+-free cells. A membrane potential was established by a diffusion potential either of H+ in the presence of carbonyl cyanide p-trifluoromethoxyphenylhydrazone or of SCN-. These results support the hypothesis of a Na+-glutamate cotransport. Na+-driven glutamate transport was also observed in wild-type E. coli B but not in a strain of K-12.

Biological Transport, Active↗
PubMedDate not supplied

Asthma management: how effective is it in the community?

BACKGROUND: The National Asthma Campaign (NAC) was launched in Australia in 1989 with the major objective of improving asthma management through the implementation of a six-step asthma management plan. AIM: The objective of the present study was to analyse the management of asthma in a cohort of adults with self-reported asthma 10 years after the commencement of the NAC. METHODS: The subjects were participants in the laboratory phase of a cross-sectional epidemiological study conducted in Melbourne in 1999-2000. Participants completed the detailed European Community Respiratory Health Survey, which included specific questions about their asthma management. Participants were included in this analysis if they had a positive response to the question 'Have you ever had asthma?'. This resulted in a total of 435 subjects. RESULTS: Of the subjects with self-reported asthma, over half of the participants reported that a doctor had ever measured their breathing (52.9%). However, only 10.1% of participants reported that they owned a peakflow meter (PFM) and only 13.3% reported that they had ever been given a written action plan. In comparison with data reported from 1993, doctor measurement of lung function has decreased significantly (P < 0.000 1), as has PFM ownership (P < 0.0001) and, importantly, possession of a written action plan (P = 0.0004). CONCLUSIONS: Asthma management among adults still falls well short of NAC guidelines. The decline in some key features over recent years suggests that new management and dissemination strategies are required.

Adult↗