Kukuh Noertjojo

T-lymphocyte responses to plicatic acid-human serum albumin conjugate in occupational asthma caused by western red cedar

BACKGROUND T cells are known to play a major role in the pathogenesis of atopic allergic asthma, but it is less clear whether they are involved in occupational asthma caused by low molecular weight chemicals such as plicatic acid. OBJECTIVES We sought to determine whether peripheral blood T cells from patients with western red cedar asthma (WRCA) recognize plicatic acid (PA) conjugated to human serum albumin (HSA) as judged by proliferation or cytokine production and to analyze the response to PA inhalation with flow cytometry. RESULTS Significant proliferative responses to PA-HSA were observed in eight of 33 patients with WRCA, none of 10 exposed nonasthmatic cedar workers, and one of 18 nonasthmatic control subjects. Two of 25 patients with WRCA also showed proliferative responses to unconjugated PA. All the WRCA responders were either currently exposed to cedar or had ceased exposure within the preceding 2 years. None of the four patients receiving oral steroids responded, but inhaled steroids did not seem to influence responsiveness. No correlations were found between the maximum stimulation response and any of the current FEV1 values, the current PC20 methacholine values, or the magnitude of the late asthmatic response to PA. Peripheral blood T-cell subset proportions and their degree of activation were similar in patients with WRCA and exposed control subjects. There was no change in T-cell phenotypes or their activation markers after PA inhalation challenge. In vitro, PA-HSA stimulation did not affect subset ratios but led to release of small amounts of IL-5 and IFN-gamma, with no detectable increase in IL-4. CONCLUSIONS PA-HSA-specific T lymphocytes seem to be present in small numbers in the peripheral blood of patients with WRCA and may respond to antigenic exposure by producing IFN-gamma and IL-5. However, the proportion of responding cells would appear to be lower than in comparable studies of atopic asthma.

Exposure and sensitization to cat dander: Asthma and asthma-like symptoms among adults☆☆☆★

BACKGROUND Several pets, such as cats, dogs, and rodents, are known to produce allergens. Despite the clinical and laboratory evidence that exposure to pets can cause bronchoconstriction in sensitized subjects, the results of population studies have been contradictory. OBJECTIVES The purpose of this study was to investigate the relationship between cat ownership and the prevalence of asthma, asthma-like symptoms, and bronchitic symptoms among subjects 20 to 44 years of age in Vancouver, Canada and to determine whether sensitization is responsible for such an association. METHODS Two thousand nine hundred ninety-nine (88%) randomly selected subjects responded to a mail questionnaire. Of these, 504 participated in laboratory examination, including allergy skin testing. RESULTS One thousand nineteen study responders (34%) were pet owners at the time of the study (current owners). Current pet owners were found to have a higher prevalence of current asthma, asthma-like symptoms, and bronchitic symptoms compared with those without pets. Cat owners had significantly higher risk of having current asthma and asthma-like symptoms. In the subset who had allergic skin tests, we found that those who were allergic to cat dander had a significantly higher risk of current asthma than those not allergic to cat dander and not owning a cat. CONCLUSION This study provides evidence that sensitization to cat dander is a more important risk factor for current asthma and asthma-like symptoms than cat ownership itself.

In vitro T-lymphocyte response and house dust mite–induced bronchoconstriction

BACKGROUND There is considerable evidence that T cells may play an important role in asthma. The purpose of this study was to determine whether the responsiveness of T lymphocytes to mite allergen stimulation in vitro is a determinant of bronchial response to house dust mite (HDM) allergen challenge in subjects who are allergic to HDM. METHODS Peripheral blood was taken from seven healthy nonatopic subjects and 23 subjects with positive skin test reactions to HDM. Of the subjects in the latter group, 16 had an asthmatic reaction on inhalation challenge with HDM extract (HDM-responders), whereas the remaining seven had a negative reaction (HDM allergic). The proportion of subsets of T lymphocytes and their activation and the amount of IL-2, IL-4, IL-5, and interferon-gamma released in the supernatants with and without stimulation with the HDM extract were determined. RESULTS Without stimulation, the proportions of subsets of T lymphocytes and their activation were similar between groups. When stimulated with the HDM allergen, the proportion of CD4+CD25+ cells from HDM responders was significantly higher than those in the control group. Comparison within groups of cell cultures with and without stimulation with the mite allergen showed that the proportion of CD4+, CD4+CD25+, CD4+/CD8+, and CD3+HLADR+ cells were significantly increased in HDM responders with stimulation; there was a trend for CD4+CD25+ cells to be increased in the HDM-allergic subjects; no increase in any T-lymphocyte subsets was found in the control subjects. The release of IL-5 was significantly greater in HDM responsers than in the other two groups. The severity of the immediate asthmatic reaction was significantly associated with the degree of nonallergic bronchial hyperresponsiveness and the amount of IL-5 released but not with the level of specific IgE to the mite allergen or subsets of T lymphocytes with and without stimulation. CONCLUSION The findings suggest that responsiveness of T lymphocytes to allergen challenge in vitro may play a role in determining the bronchial response to the allergen in vivo.

Changes in blindness prevalence over 16 years in Malawi: reduced prevalence but increased numbers of blind

Background/aims: In the coming two decades significant increases in the burden of blindness are anticipated unless concerted efforts are made to improve eye care in developing countries. Evidence of changing prevalence rates or numbers of blind people are few. The change in blindness prevalence and the number of blind people in an adult population of Malawi was measured over a 16 year period. Methods: In 1999 a population based survey of blindness in adults (age 50+) was conducted in Chikwawa district of Malawi. Visual acuity and cause of vision loss were recorded for each eye independently. Blindness was defined as presenting better eye vision of <6/60. Findings from a 1983 survey of blindness in the same district (using similar methods) were re-analysed to be comparable with the survey conducted in 1999. Results: Among 1630 enumerated adults 89% were examined. The age adjusted prevalence of blindness in the adult population was 5.4% and more common in women than men. In each age group the prevalence of blindness was lower in 1999 than in 1983; the overall reduction in blindness was 31%. During this period the 50+ population in Malawi increased almost twofold. Extrapolating the Chikwawa district data to the Malawi population reveals that the number of blind people has increased by 24%; the increase is primarily because of the large increase in the size of the most elderly group, aged 70 and above. Conclusion: The majority of blind people in Chikwawa (1983 and 1999) are in the age group 70 and over. This group has had the largest proportional increase in population size in this time. Services in this population have improved in the intervening 16 years and yet there was still an increase in the number of blind people. There was little change in excess blindness in women, suggesting that the same barriers that prevented utilisation of services in 1983 probably persist in 1999. Efforts to reach the most elderly and to reach women are needed to lead to a reduction in blind people in settings such as rural Malawi.

Effect of Application of Benzyl Benzoate on House Dust Mite Allergen Levels

BACKGROUND Several acaricides have become available for reducing house dust mite allergen levels. OBJECTIVE The purpose of this study was to assess whether the use of benzyl benzoate (Acarosan) provides additional benefit to the usual mite control measures including encasement of mattress and pillows with vinyl covers. METHODS A randomized controlled trial was carried out in 26 homes (14 control versus 12 treatment) of asthmatic patients in two cities (Vancouver and Winnipeg). The control group had the usual house dust mite control measures including the use of vinyl covers for mattresses and pillows while the treatment group had application of benzyl benzoate to mattresses and carpets in the bedroom and the most commonly used room, in addition to the above control measures. Mite allergen levels were measured 3 months and immediately before, 1 week, and 1 and 3 months after the application of house dust mite control measures. Patients kept diary cards on asthma symptoms and peak expiratory flow rates morning and evening one month before and three months after the onset of mite allergen control measures. RESULTS A reduction of mite allergen level was found in mattress samples in both groups, statistically significant at all times in the treatment group and at one and three months in the control group. Mite allergen levels on floor carpets also showed progressive reduction in both groups, but were significantly different in the treatment group (compared with controls) at 1 week, and were lower compared with baseline in the treatment group up to 3 months. No significant changes in asthma symptoms, peak expiratory flow rates, spirometric measurements, or bronchial hyperresponsiveness were observed among treatment or control group subjects. CONCLUSION The addition of benzyl benzoate to conventional house dust mite control measures resulted in a significant reduction in floor carpet dust mite levels that persisted for 3 months. The results of this study should be confirmed in a larger and longer study.

Cataract surgical outcome at the Vancouver Eye Care Centre: can it be predicted using current data?

BACKGROUND Patients selected for cataract surgery have an increasingly wider range of coexisting ocular and systemic diseases. The aim of this study was to determine whether preoperative patient characteristics can assist surgeons in identifying patients who are at increased risk of having little or no improvement in visual outcome after cataract surgery. METHODS We prospectively studied a randomly selected subset (20%) of patients with cataract undergoing cataract extraction at a tertiary centre in Vancouver. There were no patient exclusion criteria. Pre-, intra- and postoperative clinical data were collected from medical records. RESULTS We studied 1329 cataract surgical procedures from March 1999 to December 2000. Of the 1329, 851 had complete pre- and postoperative visual acuity data. The mean age of the 851 patients was 73.2 (standard deviation 10.6) years, 575 (67.6%) were women, and 472 procedures (55.5%) were first-eye procedures. Preoperatively, the best-corrected visual acuity was 20/40 or better in 146 eyes (17.2%), 20/50 in 173 (20.3%), 20/60 to 20/70 in 248 (29.1%), and 20/80 or worse in 284 (33.4%). Almost half of the patients (419 [49.2%]) had at least one coexisting eye disease in the operated eye. At about 3 months postoperatively, the best-corrected visual acuity had improved in 786 eyes (92.4%), remained the same in 42 (4.9%) and had worsened in 23 (2.7%). Of the 23 eyes with worse visual acuity, half had preoperative visual acuity of 20/40 or better; most of the remaining eyes had preoperative vision of 20/50 to 20/70. Of the 42 eyes with unchanged vision, 22 (52%) had preoperative visual acuity worse than 20/100; the remaining eyes were distributed across the visual acuity range. An increase of 1 year of age increased the odds of having a poor visual acuity outcome by 2% to 4%. Worse preoperative visual acuity predicted an increased likelihood of a poor outcome; this effect increased sharply for eyes with preoperative visual acuity of 20/80 or worse. After adjustment for age and preoperative visual acuity, patients with three or more coexisting eye diseases in the operated eye were 10 to 24 times more likely to have the worst postoperative visual acuity. INTERPRETATION The presence and number of coexisting ocular diseases, increased age and poor preoperative visual acuity predicted an unchanged or worse visual acuity after cataract surgery.