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Biomedical subjects

I Broder

Publications and source records attributed to I Broder.

At least 19 recordsLinked to original sources
PubMed2001

The role of symptomatic colds in asthma exacerbations: Influence of outdoor allergens and air pollutants.

BACKGROUND: Both air pollutants and respiratory viral infections have been recognized to be important triggers of asthma exacerbations, but the possible interaction of these has not been assessed in an epidemiologic study. OBJECTIVE: In this study, we aimed to assess the possible associations of symptomatic colds with outdoor allergens and air pollutants in exacerbating asthma. METHODS: A total of 57 adults and children with asthma participated in a 1-year study in Vancouver, British Columbia. Diary cards recording symptoms of asthma and colds, medication usage, and peak expiratory flow rates were completed twice daily. Outdoor air pollutant levels and levels of pollen and fungal spores were measured. Levels were examined for associations with exacerbations of asthma with symptoms of a cold, as compared with asthma exacerbations with no cold symptoms and colds in the absence of asthma exacerbations. RESULTS: Of 130 asthma exacerbations, 47% were associated with cold symptoms (accounting for 44% of episodes of colds). Asthma exacerbations with colds were associated with higher levels of sulfur dioxide, and nitric oxide during March to November in comparison with asthma exacerbations without cold symptoms (P <.018). Cold-symptom days overall were more common in winter and were significantly associated with lower temperatures, lower ozone levels, and higher sulfur dioxide, nitrogen dioxide, nitrogen oxide (NO and NO(x)), and carbon monoxide levels. CONCLUSIONS: Asthma exacerbations are commonly associated with cold symptoms. These episodes are associated with higher levels of sulfur dioxide and nitrogen oxides from March to November in comparison with asthma exacerbations without cold symptoms.

Adolescent↗
PubMed2000

Asthmatic subjects symptomatically worse at work: prevalence and characterization among a general asthma clinic population.

STUDY OBJECTIVES: To assess the prevalence of a historical occupational component to asthma in an adult asthma clinic and to compare characteristics of asthmatic subjects with and without work-attributed symptoms. DESIGN: A retrospective review of data obtained from a physician-administered questionnaire, answers to which were obtained at the initial patient visit of asthmatic subjects, and which included specific questions regarding the relationship of work to symptoms. Chart review data were used to supplement information on workplace exposures and investigations. SETTING: A university-based secondary- and tertiary-referral asthma clinic. PATIENTS: Seven hundred thirty-one adult asthmatic subjects who were referred for assessment and management of asthma. INTERVENTIONS: Statistical analyses of asthmatic subjects with and without work-attributed symptoms and a determination, from chart review, of the likelihood of causes for symptomatic worsening of asthma at work. MEASUREMENTS AND RESULTS: Sixty percent of the patients (435) had adult onset of asthma, among whom 310 patients (71%) were employed at the time of their visit. Fifty-one patients reported their asthma to be worse at work (ie, 16% of adult-onset working asthmatic subjects). Sixteen of these patients (31%) had likely or possible sensitizer-induced occupational asthma (OA), and 49% likely had aggravation of underlying asthma. The other 20% of patients had possible OA or aggravation of underlying asthma at work. CONCLUSIONS: Adult-onset asthmatic subjects commonly report a worsening of asthma at work, more commonly on the basis of likely aggravation of underlying asthma than on the basis of likely or possible OA.

Adolescent↗
PubMed1999

The outcome of asthma related to workplace irritant exposures: a comparison of irritant-induced asthma and irritant aggravation of asthma.

STUDY OBJECTIVES: (1) To characterize workers' compensation claims accepted on the basis of new-onset asthma associated with accidental high respiratory irritant exposure at work; (2) to compare the frequency, characteristics, and outcomes in this group of workers to workers who were compensated for an exacerbation of preexisting asthma associated with accidental high respiratory irritant exposure at work. DESIGN: A retrospective review was performed of 469 asthma claims accepted by the Ontario Workers' Compensation Board (WCB) between 1984 and 1988. Among these, claims attributed to an accidental high respiratory irritant exposure at work were classified into two groups: one group with reported preexisting asthma prior to the exposure (accidental aggravation of asthma [AAA]) and another group with no previous history of asthma (irritant-induced asthma [IIA]). RESULTS: Of the 469 claims, 89 subjects (19%) had symptoms related to accidental high respiratory irritant exposure in the workplace; of these, 68 subjects (76%) had AAA, 12 subjects (13%) had IIA, and 9 subjects (10%) had possible IIA but were excluded from the analysis because of insufficient data. Those with IIA had a longer duration of work-attributed symptoms (mean, 219 +/- 208 days) than the subjects with AAA (mean, 32 +/- 38 days; p < 0.001). Nine subjects (75%) with IIA were no longer in the same work environment, while 47 subjects in the AAA group (71%) were still in the same work environment (p < 0.001). The most common triggering agent for subjects with IIA was an isocyanate spill; for those with AAA, the most common triggering agent was paint. CONCLUSIONS: The WCB-accepted claims related to accidental, high respiratory irritant exposure at work are more commonly assigned to the category of AAA than to IIA. IIA patients in this claimant group had a longer mean duration of work-attributed respiratory symptoms, perhaps due to a need for a larger (and thus less common) irritant exposure to induce asthma in previously normal subjects.

Adult↗
PubMed1997

Outcome determinants for isocyanate induced occupational asthma among compensation claimants.

OBJECTIVES: To compare the outcome of occupational asthma (OA) induced by isocyanates in Ontario (where a surveillance programme for exposed workers has been in place for over 15 years), with the outcome of OA induced by other work agents. METHODS: Compensated OA claims during the period 1984-88 in Ontario were retrospectively reviewed in a standardised way. RESULTS: 136/235 compensated claims were attributed to isocyanates. Compared with other causes of OA, those attributed to isocyanates had a shorter latent period before onset (5.9 v 7.9 years, P < 0.05), shorter duration of symptoms before diagnosis (2.0 v 3.0 years, P < 0.05), and less associated atopy (43% v 58%, P < 0.05). Outcome at a mean of 1.9 years after initial assessment was significantly better in those with OA induced by isocyanates; 73% cleared or improved v 56% with other causes of OA (P < 0.05). Ten subjects with OA induced by isocyanates stayed at the same work; none cleared and four had worsened at follow up. A better outcome in OA induced by isocyanates was associated with early diagnosis (P < 0.05), and early removal from isocyanates after the onset of asthma. CONCLUSIONS: The outcome in the group with OA induced by isocyanates is similar to previous follow up studies. However, it is better than the outcome in our comparison group with OA due to other causes, perhaps because of earlier diagnosis in the group with OA induced by isocyanates. This may be attributable to the medical surveillance of workers exposed to isocyanates in Ontario, either directly from the surveillance assessments, or indirectly by increasing awareness of the condition.

Adult↗
PubMed1996

Recommendations for reducing the effect of grain dust on the lungs. Canadian Thoracic Society Standards Committee.

OBJECTIVE: To assess the appropriateness of the current Canadian standards for exposure to grain dust in the workplace. OPTIONS: The current permissible exposure limit of 10 mg of total grain dust per cubic metre of air (expressed as mg/m3) as an 8-hour time-weighted average exposure, or a lower permissible exposure limit. OUTCOMES: Acute symptoms of grain-dust exposure, such as cough, phlegm production, wheezing and dyspnea, similar chronic symptoms, and spirometric deficits revealing obstructive or restrictive disease. EVIDENCE: Articles published from 1924 to December 1993 were identified from Index Medicus and the bibliographies of pertinent articles. Subsequent articles published from 1994 (when the recommendations were approved by the Canadian Thoracic Society Standards Committee) to June 1996 were retrieved through a search of MEDLINE, and modification of the recommendations was not found to be necessary. Studies of interest were those that linked measurements of total grain dust levels to the development of acute and chronic respiratory symptoms and changes in lung function in exposed workers. Papers on the effects of grain dust on workers in feed mills were not included because other nutrients such as animal products may have been added to the grain. Unpublished reports (e.g., to Labour Canada) were included as sources of information. VALUES: A high value was placed on minimizing the biological harm that grain dust has on the lungs of grain workers. BENEFITS, HARMS AND COSTS: A permissible exposure limit of 5 mg/m3 would control the short-term effects of exposure to grain dust on workers. Evidence is insufficient to determine what level is needed to prevent long-term effects. The economic implications of implementing a lower permissible exposure limit have not been evaluated. RECOMMENDATIONS: The current Canadian standards for grain-dust exposure should be reviewed by Labour Canada and the grain industry. A permissible exposure level of 5 mg/m3 is recommended to control short-term effects. Further measurements that link the levels of exposure to respiratory health effects in workers across Canada should be collected to establish an exposure-response relation and possible regional differences in the effects of grain dust. VALIDATION: There has been no external review of these recommendations. However, the American Conference of Governmental Industrial Hygienists has recommended an 8-hour average exposure limit of 4 mg/m3 for wheat, oats and barley.

Air Pollutants, Occupational↗
PubMed1995

Assessment of ozone exposures in the greater metropolitan Toronto area.

An ozone (O3) exposure assessment study was conducted in Toronto, Ontario, Canada during the winter and summer of 1992. A new passive O3 sampler developed by Harvard was used to measure indoor, outdoor, and personal O3 concentrations. Measurements were taken weekly and daily during the winter and summer, respectively. Indoor samples were collected at a total of 50 homes and workplaces of study participants. Outdoor O3 concentrations were measured both at home sites using the passive sampler and at 20 ambient monitoring sites with continuous monitors. Personal O3 measurements were collected from 123 participants, who also completed detailed time-activity diaries. A total of 2,274 O3 samples were collected. In addition, weekly air exchange rates of homes were measured.

Adolescent↗
PubMed1995

House dust mite allergen levels in two cities in Canada: effects of season, humidity, city and home characteristics.

The homes of 120 patients with asthma, 57 in Vancouver and 63 in Winnipeg, were studied. The characteristics of the homes were assessed by a questionnaire. Dust samples were collected and the indoor relative humidity was measured four times during the year covering all four seasons in both cities. Mite allergen levels were determined using monoclonal antibodies against Der p I and Der f I by the ELISA method. The mean levels of both mite allergens in mattress and floor samples in the homes in Vancouver and in Winnipeg were relatively low for all seasons. Mite allergen levels were found to be associated with city, season and individual home differences. They were significantly higher in Vancouver than in Winnipeg. Der p I and Der f I in mattress samples in both cities and Der f I in floor samples in Vancouver, varied by season. The indoor relative humidity level in the homes in Vancouver were also significantly higher than those in Winnipeg. There was, however, no significant association between the levels of indoor relative humidity and the levels of mite allergens after adjusting for variations in city, season and individual home. Although individual home differences were highly associated with mite allergen levels, only a few home characteristics were found to be related to mite allergen levels such as the type and the age of the home, the type of heating, the use of feather pillows and the number of occupants in the homes. Whether low levels of mite allergens are partially responsible for the relatively low prevalence of childhood asthma in Canada remains to be investigated.

Allergens↗
PubMed1995

Mite and cat allergen levels in homes and severity of asthma.

The relationships between mite and cat allergen levels in the home, skin test reactivity, and severity of asthma were explored in 120 asthmatic subjects, 57 in Vancouver and 63 in Winnipeg. Patients in the two cities were similar in age, gender distribution, and severity of asthma. Skin tests were performed using 13 common allergens, including D. pteronyssinus, D. farinae, and cat dander, as well as control subjects. Patients recorded their asthma symptoms, medication requirement, and twice daily peak expiratory flow rate for 1 yr. Dust samples were collected every 3 mo during each season of 1992 through 1993 in both cities. Mite and cat allergen levels were determined with an ELISA using monoclonal antibodies against Der p I, Der f I, and Fel d I. There was no relationship between skin test reactivity and levels of mite and cat allergens. In children with positive skin tests to either mite allergen, total mite (sum of Der p I and Der f I) allergen level was positively related to the mean daily symptom score and negatively related to the daily mean PEF (% of predicted). There was no such relationship among adult asthmatic patients with positive skin tests to either mite allergen. No relationship was found between cat allergen level and the severity of asthma.

Adult↗
PubMed1995

A workers' compensation claim population for occupational asthma. Comparison of subgroups.

STUDY OBJECTIVE: (1) To compare patients with claims submitted to the Ontario Workers' Compensation Board (WCB) for occupational asthma, in relation to the WCB decisions reached of occupational asthma (OA); aggravation of asthma from irritant exposures (AA); unrelated asthma; no asthma; and (2) to assess determinants of outcome of WCB accepted claims at permanent disability assessments. DESIGN: A retrospective review of 609 claims submitted to the WCB 1984 to 1988. RESULTS: The WCB decision reached was OA in 39% of claims, mostly attributed to isocyanates (57% of these). A further 39% were accepted for AA. Exposure to a known sensitizer occurred in 91% with OA and to an irritant in 67% with AA. Forty percent with AA were attributed to a spill or accidental exposure and 68% had preceding asthma. Those with AA were more likely to have clearing of symptoms by the time of their main assessment (43% vs 20% with OA) and were more likely to have remained in the same work (35% vs 20% with OA). Of 200 OA accepted claims reviewed at a mean of 1.9 years later, clearing of asthma occurred in 19% and milder asthma in 47%. Outcome was best with early diagnosis (p < 0.05), and milder impairment of pulmonary function at initial assessment (p < 0.05). CONCLUSIONS: Patients with asthma induced by a workplace sensitizer demonstrate some differences from those related to workplace irritants. Accurate categorization and early removal of those with OA offers the best prognosis.

Adult↗
PubMed1992

Sustained improvement in asthma with long-term use of formoterol fumarate.

Inhaled formoterol fumarate, a long acting beta 2 agonist, produces bronchodilatation that is sustained for approximately 12 hours. To determine whether such bronchodilator effects are maintained and asthma control sustained during chronic administration, we monitored airflow indices and clinical control in 112 asthmatic patients who self administered formoterol twice daily for periods ranging from 9 to 12 months. Subjects were recruited immediately following completion of a 3-month double-blind comparison of formoterol, 12 micrograms, bid versus salbutamol, 200 micrograms, qid. Assessments were conducted at baseline, 3, 6, and 9 months, where baseline represents the final visit of the 3-month comparative study. Patients were asked to complete diary cards and twice daily PEFR for a 2-week period before each assessment. Throughout the follow-up study, there was no indication of worsening of asthma control or deteriorating lung function. For the patients who continued to receive formoterol, the previous improvement in asthma control and lung function was maintained at the level reached in the 3-month study. There was an improvement in flow rates and asthma symptoms in the group switched from salbutamol to formoterol by the first clinic visit. This improvement in asthma control and lung function was maintained over the subsequent 6 months. Formoterol was well tolerated during the study period. We conclude that prolonged use of formoterol fumarate twice daily results in sustained improvement in symptoms and flow rates in asthma with no evidence of tachyphylaxis.

Adolescent↗
PubMed1991

A three-month comparison of twice daily inhaled formoterol versus four times daily inhaled albuterol in the management of stable asthma.

We compared the efficacy of inhaled formoterol, a long-acting beta 2-agonist, with inhaled albuterol in 145 stable adult asthmatics in a 12-wk multicenter trial. Patients were allocated in randomized double-blind fashion to maintenance therapy with either formoterol 12 micrograms twice a day or albuterol 200 micrograms four times a day in addition to their other asthma medications. Patients were allowed to use "rescue" 100-micrograms albuterol puffs on an as-needed basis. Mean baseline FEV, in the morning before bronchodilator was 2.14 +/- 0.76 L and 1.98 +/- 0.71 L for the formoterol and albuterol groups, respectively, these values being used as baseline covariates in subsequent analysis of predrug and postdrug FEV1. Measured at each clinic visit, morning predrug FEV1 rose significantly with formoterol treatment and was significantly greater at all visits than in the albuterol group, the greatest difference being in Week 8 (2.40 +/- 0.77 versus 1.92 +/- 0.66 L, p less than 0.001). Morning FEV1 30 min postdrug was significantly higher in the formoterol group at Weeks 2 and 8, the trend not reaching statistical significance at other times. Diurnal variation in prebronchodilator peak flow rates was significantly reduced in the formoterol group throughout the trial (17 versus 42 L/min at Week 12, p less than 0.0001). The number of asthma episodes per week was significantly less in the formoterol group during Weeks 4, 8, and 12 as were the number of sleep disruptions during Weeks 2, 4, 6, 8, and 12. Significantly more rescue albuterol was required in the albuterol group by Week 2 and throughout the remainder of the study.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Inhalation↗
PubMed1991

Formaldehyde exposure and health status in households.

This report describes a case study concerned with acute and subacute health effects of formaldehyde in the indoor air, which is based on a large group of control houses and houses retroinsulated 4 to 5 years earlier with urea formaldehyde foam insulation (UFFI). Both groups underwent an environmental and health assessment on two occasions separated by an interval of 12 months, during which about one-half of the UFFI group performed remedial work on their houses. The results show that in the first survey of the study population, before remedial work, there was a moderate excess of many adverse health status indicators among the UFFI subset relative to the controls. This was associated with the presence of direct exposure-response relationships between formaldehyde levels in the UFFI houses and the prevalence of a number of symptoms. No comparable relationships were seen among the controls. At the second survey, performed following the removal of the UFFI, there was an appreciable reduction in the excess of most adverse health status indicators among the UFFI subjects. This improvement in health status among the UFFI removal subset was not associated with any significant diminution of formaldehyde exposures, although the previously observed exposure-response relationships had vanished. These observations imply that the findings obtained in the preremedial stage of the study cannot be explained by formaldehyde exposure alone.

Adult↗
PubMed1991

Outcome of assessments for occupational asthma.

Among 154 referrals to a university hospital clinic for assessment of possible occupational asthma, the feasibility and results of different investigations were assessed using a consistent approach to all patients. A positive skin test to a workplace allergen (14 percent of all subjects), positive peak flow workplace changes (12 percent), improvement in methacholine response on holiday (9 percent), and/or positive specific challenge testing (14 percent) supported the diagnosis of occupational asthma in 61 subjects (39 percent of the total referrals). Fifty-one of these were related to a workplace sensitizer and ten to a presumed irritant. Occupational asthma was excluded in 48 subjects (31 percent) who had normal methacholine responsiveness within 24 hours of work (22 percent of the 154 subjects), peak flow readings no worse at work than on holidays (14 percent of the total referrals) and/or negative specific challenge testing (10 percent of the total referrals). Insufficient information could be obtained for a diagnosis in the remaining 45 subjects (28 percent). No single investigation was considered diagnostic in this study, as each could be positive or negative for other reasons.

Adult↗
PubMed1989

Irritant-induced occupational asthma.

A retrospective review was performed on the files of 154 consecutive workers assessed for occupational asthma to clarify the relative frequency of asthma induced by irritants in the workplace and to determine whether such asthma was clearly distinguishable from other forms of occupational asthma. Fifty-nine workers were considered to have occupational asthma. A subset of ten had a history consistent with asthma initiated by exposure to high concentrations of an irritant, had persistent symptoms for an average of five years when seen, demonstrated increased reactivity to methacholine, and gave no prior history of pulmonary complaints. These ten had a lower incidence of atopy (20 percent vs 58 percent) and a more frequent history of smoking (80 percent vs 38 percent) than the other subjects with occupational asthma but did not differ in average latency (5.9 years vs 5.7 years). Our findings suggest that irritant-induced asthma is not uncommon, and those affected may have different baseline characteristics from others with occupational asthma.

Adult↗
PubMed1989

Health status and sulfur dioxide exposure of nickel smelter workers and civic laborers.

We examined a group of 143 nickel smelter workers who processed a high sulfide ore, and compared their health status with that of 117 civic laborers. All subjects were studied over the first four days of a week of work, administering a health questionnaire on day 1, measuring their pulmonary function on the morning of day 1 and day 4, and monitoring their personal exposure to SO2 and particulates over the same period. The smelter workers were exposed to an average of 0.374 mg/m3 of respirable particulates, a threefold higher level than the controls, and to 0.67 ppm of sulfur dioxide, a 40-fold greater amount than the controls, but were found to show no excess of chronic respiratory symptoms and did not differ from the controls either in their baseline pulmonary function or in their change from the morning of day 1 to day 4. However, there were several indicators of a healthy worker effect in the smelter worker group.

Air Pollutants, Occupational↗
PubMed1988

Grain dust contains a tannin-like material which fixes complement.

Grain dust extract has been found to activate complement. We investigated the possibility that this activity was due to tannin by comparing the characteristics of grain dust extract with those of tannic acid. The properties that were studied were the interaction with albumin and immunoglobulin G, the stability to heat, and the adsorption to polyvinylpolypyrrolidone and hide powder. Grain dust extract was found to show similarities with tannic acid which were consistent with the presence of tannin accounting for most of its complement fixing activity.

Complement Fixation Tests↗
PubMed1988

Comparison of health of occupants and characteristics of houses among control homes and homes insulated with urea formaldehyde foam. I. Methodology.

The methodology of a study in which a comparison is made of the health and house characteristics of the occupants of 231 control homes and 571 houses containing urea formaldehyde foam insulation (UFFI) is described. All homes and occupants were examined on two occasions separated by an interval of 12 months, during which two-thirds of the UFFI houses performed remedial work. The occupants were examined using a health questionnaire and a series of objective tests including pulmonary function, nasal airway resistance, sense of smell, nasal surface cytology, and patch tests. The houses were assessed using a questionnaire and measurements of indoor formaldehyde and carbon dioxide levels. No obvious bias has been identified in this survey with respect to the representativeness of the population studied, the classification of the UFFI and control groups, and the input from both the respondents and observers. The symptom responses made by individuals within the same households were not correlated. Quality control assessment of the objective health tests and formaldehyde sampling and assays demonstrated that these procedures remained stable over the two phases of the study, with the exception of the expected decrease in the pulmonary flow rates over 1 year and a small unexpected increase in the forced vital capacity and the forced expiratory volume in 1 s.

Airway Resistance↗