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Biomedical subjects

P Brassard

Publications and source records attributed to P Brassard.

At least 19 recordsLinked to original sources
PubMed2006

The use of environmental factors as adjuncts to traditional tuberculosis contact investigation.

SETTING: A 25-year-old university student was diagnosed with cavitary pulmonary and laryngeal tuberculosis following symptoms of underlying cough of 6 months' duration. OBJECTIVES: To estimate the hourly risk of infection (HRI) and examine the role of environmental factors, including room size and ventilation, in modulating this risk. METHODS: Contact investigation. RESULTS: Of 1100 contacts identified, 78.3% (n = 896) received a tuberculin skin test (TST), of whom 27.5% had a positive result. Among 634 Canadian-born contacts tested, 22.7% had a positive TST. The independent risk factors for a positive TST among Canadian-born university students were: > 35 h spent with the index case (adjusted OR 6.6, 95% CI 1.0-44.9) and smaller classroom size (aOR 5.0, 95% CI 1.4-10.0). In the first school term, the HRI among Canadian-born student contacts was 0.9%; in the second term, it was 1.6%. CONCLUSION: There are inherent limitations in generalising findings from an outbreak investigation, due to the considerable variation in the infectiousness of cases. Nevertheless, in situations where the index case has a high degree of infectiousness, and there are numerous contacts with low expected prevalence of infection, the HRI can, together with ventilation measurements, be useful in guiding the extent of contact investigation needed.

Adult↗
PubMed2005

Tuberculosis surveillance among new immigrants in Montreal.

SETTING: Foreign-born persons account for over 60% of Canadian tuberculosis (TB) incidence; immigrants with TB-related lung scarring ('inactive TB') are at particularly high risk, and represent an important target for preventive efforts. OBJECTIVE: To document the performance of the immigrant surveillance programme for inactive TB in Montreal. DESIGN: All immigrants arriving with inactive TB are referred by the public health department to the Montreal Chest Institute. We prospectively recorded clinical and radiographic data for those evaluated in 1999 and 2000. We examined physicians' adherence to Canadian guidelines. We also evaluated concordance of chest radiographic interpretation. RESULTS: Of 1444 immigrants notified, 792 (55%) were sent referral letters. Most of the others lacked valid addresses. Of the 654 (45%) who were examined, 322 (22%) were diagnosed with untreated latent TB, 215 (15%) were recommended therapy, and 156 (11%) completed it. Of 388 potential candidates for treatment of latent TB, 274 (71%) underwent tuberculin tests. Treatment decisions followed guidelines for 87% of patients with full testing. Agreement between clinicians and chest radiologists as to TB-related radiographic abnormalities was frequent (K 0.63). Six 'high volume' clinicians performed better than others with respect to management and radiographic interpretation. CONCLUSION: Centralised post-immigration surveillance requires more accurate referrals, and more consistent provider performance.

Adult↗
PubMed2004

Acceptance of screening and completion of treatment for latent tuberculosis infection among refugee claimants in Canada.

SETTING: Primary care clinic for refugee claimants, Montreal, Canada. OBJECTIVES: To identify factors linked to the acceptance of the tuberculin skin test (TST), and assess completion of treatment for latent tuberculosis infection (LTBI). DESIGN: Asylum seekers consulting for a medical complaint or medical immigration examination between February and October 1999 were assessed for eligibility. Personal and clinical information was gathered prospectively by questionnaire. Hospital files were reviewed to assess completion of LTBI treatment. RESULTS: In our study, 296 subjects (72.4% of 409 eligible) were offered TST, of whom 227 accepted (76.7%). Of these, 49 (24.9%) had a TST > or = 10 mm and 24 (49%) completed 6 months of LTBI treatment. Logistic regression models showed that patients who had never had a TST (OR 3.2, 95%CI 1.34-7.6) or had no temporary exclusion criteria (OR 4.0, 95%CI 1.6-9.9) were more likely to accept TST. Perceiving tuberculosis as a severe disease (OR 0.29, 95%CI 0.09-0.91) and consulting for an immigration examination (OR 0.42, 95%CI 0.18-0.98) was associated with refusal of TST. Increasing age was found to be independently associated with a positive TST (OR 1.06, 95%CI 1.01-1.12). Variability in the proportion of positive results was found between TST readers. CONCLUSION: This study supports the feasibility of screening refugee claimants for LTBI during medical consultation and of developing organizational links to ensure completion of LTBI treatment.

Adolescent↗
PubMed2004

Yield of tuberculin screening among injection drug users.

BACKGROUND: Regardless of their HIV status, injection drug users (IDUs) are at increased risk of developing active tuberculosis (TB) if they have latent TB infection (LTBI). We quantified the prevalence and predictors of LTBI and level of adherence to medical evaluation in a population of IDUs in Montreal. METHODS: Participants were recruited from an ongoing dynamic cohort of IDUs followed for HIV seroconversion risk behaviour. Subjects with a tuberculin skin test (TST) of > or =5 mm were referred to designated TB clinics for medical evaluation. A financial incentive was provided for TST readings. RESULTS: Of the 262 subjects tested, 246 (94%) returned for TST reading. The overall prevalence of positive TSTs was 22% (5% in HIV-positive, 28% in HIV-negative participants). Older age at first injection drug use (OR per 10 year increase in age 1.4, 95%CI 1.2-1.8), duration of injection drug use (OR per 10 year increase 1.6, 9.5%CI 1.5-2.2) and negative HIV status (OR 11.2, 95%CI 3.2-4.0) were independent predictors of a positive TST. Nine per cent of all TST-positive participants completed LTBI treatment. CONCLUSION: TB screening activities with incentives can be successful in detecting TST-positive individuals, but better strategies are needed for medical follow-up in this high-risk group.

Adult↗
PubMed2001

Iron promotes cadmium binding to citrate.

Iron-cadmium interactions are important in cadmium toxicity. Dietary iron supplements may decrease cadmium retention after oral cadmium exposure but the underlying mechanism is not known. Using a CdS/AgS ion selective electrode to measure [Cd2+] in physiological saline solution at pH 7.4, we show that Fe2+ promotes Cd2+ binding to citrate thereby decreasing the availability of free Cd2+. This suggests the formation of high molecular weight Cd2+-Fe2+-citrate complexes. We confirm this suggestion by showing that 109Cd2+ is retained by 1 kDa cut off filters when present with total 50 microM Fe2+ plus 1 mM citrate but not when present with citrate alone. The formation of high molecular weight complexes may prevent Cd2+ absorption. As citrate is part of the diet, we suggest that these iron-cadmium interactions may contribute to the protective effect of iron against cadmium toxicity.

Binding, Competitive↗
PubMed2001

Calcific shoulder tendinitis: treatment with modified US-guided fine-needle technique.

PURPOSE: To evaluate clinical response to treatment of calcified tendinitis of the shoulder by using a modified percutaneous ultrasonography (US)-guided fine-needle technique. MATERIALS AND METHODS: Thirty shoulders of 30 consecutive patients (23 women, seven men; mean age, 47.4 years) with chronic shoulder pain (average duration, 43.1 months) refractory to medical treatment were treated percutaneously by using a fine needle and US guidance. Patients were prospectively evaluated by using a shoulder pain and disability index consisting of 13 items and divided into two subcategories: pain and disability. The patient completed the questionnaire before the procedure and during the follow-up visit approximately 1 month later. A diagnostic US examination was also performed at that time. RESULTS: There was a statistically significant improvement in the shoulder pain and disability index total score (27.0%) and the pain (30.5%) and disability (23.9%) scores. According to the index, these results indicate a significant clinical response. CONCLUSION: This modified US-guided fine-needle technique for calcified tendinitis of the shoulder appears to be an effective therapy and was less aggressive than previously described percutaneous techniques.

Adult↗
PubMed2000

Atovaquone and azithromycin for the treatment of babesiosis.

BACKGROUND: Babesiosis is a tick-borne, malaria-like illness known to be enzootic in southern New England. A course of clindamycin and quinine is the standard treatment, but this regimen frequently causes adverse reactions and occasionally fails. A promising alternative treatment is atovaquone plus azithromycin. METHODS: We conducted a prospective, nonblinded, randomized trial of the two regimens in 58 subjects with non-life-threatening babesiosis on Nantucket, on Block Island, and in southern Connecticut. The subjects were assigned to receive either atovaquone (750 mg every 12 hours) and azithromycin (500 mg on day 1 and 250 mg per day thereafter) for seven days (40 subjects) or clindamycin (600 mg every 8 hours) and quinine (650 mg every 8 hours) for seven days (18 subjects). RESULTS: Adverse effects were reported by 15 percent of the subjects who received atovaquone and azithromycin, as compared with 72 percent of those who received clindamycin and quinine (P<0.001). The most common adverse effects with atovaquone and azithromycin were diarrhea and rash (each in 8 percent of the subjects); with clindamycin and quinine the most common adverse effects were tinnitus (39 percent), diarrhea (33 percent), and decreased hearing (28 percent). Symptoms had resolved three months after the start of therapy in 65 percent of those who received atovaquone and azithromycin and 73 percent of those who received clindamycin and quinine (P=0.66), and after six months no patient in either group had symptoms. Three months after the completion of the assigned regimen, no parasites could be seen on microscopy, and no Babesia microti DNA was detected in the blood of any subject. CONCLUSIONS: For the treatment of babesiosis, a regimen of atovaquone and azithromycin is as effective as a regimen of clindamycin and quinine and is associated with fewer adverse reactions.

Adult↗
PubMed2000

On the Ca2+ dependence of non-transferrin-bound iron uptake in PC12 cells.

Non-transferrin-bound iron (NTBI) uptake has been reported to follow two pathways, Ca(2+)-dependent and Ca(2+)-independent (Wright, T. L., Brissot, P., Ma, W. L., and Weisiger, R. A. (1986) J. Biol. Chem. 261, 10909-10914; Sturrock, A., Alexander, J., Lamb, J., Craven, C. M., and Kaplan, J. (1990) J. Biol. Chem. 265, 3139-3145). Studies reporting the two pathways have ignored the weak interactions of Ca(2+) with the chelator nitrilotriacetate (NTA) and the reducing agent ascorbate. These studies used a constant ratio of total Fe(2+) to NTA with and without Ca(2+). We observed Ca(2+) activation of NTBI uptake in PC12 cells with the characteristics reported for other cells upon using 1 mm ascorbate and a constant ratio of total Fe(2+) to NTA with or without Ca(2+). However, Ca(2+) did not affect NTBI uptake in solutions without NTA. We then determined conditional stability constants for NTA binding to Ca(2+) and Fe(2+) by potentiometry under conditions of NTBI uptake experiments (pH, ionic strength, temperature, ascorbate, total Fe(2+), and total Ca(2+) concentrations). In solutions based on these constants and taking Ca(2+) chelation into account, Ca(2+) did not affect NTBI uptake over a range of free Fe(2+) concentrations. Thus, the Ca(2+) activation of NTBI uptake observed using the constant total Fe(2+) to NTA ratio was because of Ca(2+)-NTA chelation rather than an activation of the NTBI transporter itself. It is suggested that the previously reported Ca(2+) dependence of NTBI uptake be re-evaluated.

Animals↗
PubMed2000

Evaluation of Mycobacterium tuberculosis transmission from a pediatrician and initial compliance to prophylaxis of contacts in an outpatient pediatric clinic.

OBJECTIVE: The risk that latent infection will progress to active tuberculosis is greater in infants and children than for most other age groups. We set out to determine the rate of transmission of Mycobacterium tuberculosis to pediatric patients exposed to a pediatrician with smear-negative and culture-positive pulmonary tuberculosis. We also explored factors associated with compliance to prophylaxis. METHODS: Clinic and hospital billing records were used to identify patients age 5 or less who were seen during the pediatrician's potential contagious period. Patient were notified by registered mail of their putative exposure and were offered a tuberculin skin test screening with 5 tuberculin units of purified protein derivative (Tubersol, Connaught) and chest radiography of children with a tuberculin skin test > or =5 mm. RESULTS: A total of 456 patients were identified as exposed; 140 contacts never responded for evaluation and 93 letters were not delivered because of incorrect mailing addresses. Of the 223 who completed screening 1 (0,4%) had a initial skin test result of 8 mm. The remaining 222 contacts had repeated negative test results. The only positive child (15 months old) was born in Honduras and had received Calmette-Guerin bacillus at birth. No active tuberculosis cases were identified in the 456 contacts up to 2 years after exposure. Compliance with prophylaxis was associated with having two or less children in the household (odds ratio, 2.5; 95% confidence interval, 1.1 to 5.9). CONCLUSION: We found no evidence of transmission of M. tuberculosis in an outpatient pediatric setting. Only 43% of exposed children completed screening, and 38% of those offered prophylaxis completed their initial 3 months of therapy.

Ambulatory Care Facilities↗
PubMed2000

Comparison of cost-effectiveness of tuberculosis screening of close contacts and foreign-born populations.

Although tuberculosis (TB) screening of immigrants has been conducted for over 50 yr in many industrialized countries, its cost- effectiveness has never been evaluated. We prospectively compared the yield and cost-effectiveness of two immigrant TB screening programs, using close-contact investigation and passive case detection. Study subjects included all immigration applicants undergoing radiographic screening, already arrived immigrants requiring surveillance for inactive TB, and close contacts of active cases resident in Montreal, Quebec, Canada, who were referred from June 1996 to June 1997 to the Montreal Chest Institute (MCI), a referral center specializing in respiratory diseases. For all subjects seen, demographic data, investigations, diagnoses, and therapy were abstracted from administrative data bases and medical charts. Estimated costs of detecting and treating each prevalent active case and preventing future active cases, based on federal and provincial health reimbursement schedules, were compared with the costs for passively diagnosed cases of active TB. Over a period of 1 yr, the three programs detected 27 cases of prevalent active TB and prevented 14 future cases. As compared with passive case detection, close-contact investigation resulted in net savings of $815 for each prevalent active case detected and treated and of $2,186 for each future active case prevented. The incremental cost to treat each case of prevalent active TB was $39,409 for applicant screening and $24,225 for surveillance, and the cost of preventing each case was $33,275 for applicants and $65,126 for surveillance. Close-contact investigation was highly cost effective and resulted in net savings. Immigrant applicant screening and surveillance programs had a significant impact but were much less cost effective, in large part because of substantial operational problems.

Cohort Studies↗
PubMed2000

Tuberculosis infection in an Aboriginal (First Nations) population of Canada.

BACKGROUND: The incidence of active tuberculosis (TB) among the Cree, an Aboriginal population of Canada, is dropping, but it remains three times that of the general population. We analyzed data from tuberculin skin test (TST) surveys to determine estimates of prevalence of infection and annual risk of infection (ARI) in this population. METHODS: TST surveys targeting 12-year-old students were conducted annually from 1993 to 1998. Students with no record of previous positive TST (> or = 10 mm) were offered TST (5 TU PPD-T). Data collected included result of previous TST reading for all students, readings of TSTs performed (mm induration) and BCG (bacille Calmette-Guérin) vaccination status for those positive on TST. RESULTS: A total of 1274 children were screened (participation rate 94%). TST reaction size frequency distribution plots a bimodal curve. The prevalence of infection among 12 year olds was 15.3% over this period. ARI estimates range from 0.6 to 2.4% (average ARI 1.4%). A significant downward linear trend in ARI was observed over the period (P < 0.001). DISCUSSION: Calculated ARI may be over-estimated due to prior BCG vaccination; however, the trend in ARI confirms decreasing transmission of TB infection. Better knowledge of human immunodeficiency virus seroprevalence among pregnant women is needed to complete the evaluation of the BCG program.

BCG Vaccine↗
PubMed1999

Incidence of tuberculosis among reported AIDS cases in Quebec from 1979 to 1996.

BACKGROUND: The impact of HIV infection on tuberculosis (TB) rates in Quebec has not been fully established. Because concurrent HIV infection is the single most important factor in TB reactivation, the authors used Quebec AIDS surveillance data to quantify the extent of TB among reported AIDS cases and to identify the characteristics of AIDS patients with TB. METHODS: The study population comprised people aged 15 years and over with AIDS diagnosed between Jan. 1, 1979, and Dec. 31, 1996, and reported by Mar. 13, 1997. Patients with TB (all forms) and those without TB were compared. Multivariate logistic regression analysis was used to examine the independent effect of each variable on the AIDS-TB cases. The authors also compared the number of AIDS-TB cases with the number of TB cases to estimate the effect of HIV infection on TB incidence. RESULTS: Of the 4684 people with AIDS reported in Quebec, 242 (5.2%) had active TB at some point during the course of their illness. During 1992-1995, 9.6% of the people with TB in Montreal, and 5.8% in the province of Quebec, also had HIV infection. Those with AIDS and TB were predominantly male (75.2%), manual workers (40.1%) and residents of Montreal (86.4%) and were born in an HIV-endemic country (63.8%). The multivariate analysis indicated that AIDS patients who were born in HIV-endemic countries in the Caribbean, sub-Saharan Africa or other developing regions were 21.8 times (95% confidence interval [CI] 19.5-28.5), 17.9 times (95% CI 12.7-27.1) and 4.9 times (95% CI 3.5-7.0) more likely to have TB than those born in Canada; manual workers and unemployed people with AIDS were 1.6 times (95% CI 1.3-2.0) and 2.0 times (95% CI 1.5-2.6) more likely to have TB than professional workers; and people who acquired HIV infection through heterosexual contact were 2.1 times (95% CI 1.6-3.1) more likely to have TB than men who acquired it through sexual contact with other men. INTERPRETATION: AIDS seems to contribute significantly to the number of TB cases. The results of this study reinforce the importance of offering HIV testing to people in high-risk groups, such as those born in a country where HIV and TB is endemic.

Adolescent↗
PubMed1999

Testing for HIV among patients with tuberculosis in Montreal.

OBJECTIVE: To determine the rate of HIV testing among patients with tuberculosis (TB) in Montreal, and to identify patient characteristics associated with physician screening patterns. Knowledge of local patterns of HIV testing among patients with TB could be used to facilitate the development of strategies to improve compliance with recommendations that all patients with TB be screened for HIV. DESIGN: Retrospective chart review. PATIENTS: All patients with TB reported to the Montreal Public Health Unit from 1992 to 1994 (ages 19 to 50) and from 1992 to 1995 (ages 18 and under) and for whom a chart could be reviewed. OUTCOME MEASURES: Patients with TB screened versus not screened for HIV infection, analyzed to determine which variables independently predict the likelihood of screening for HIV infection. RESULTS: Of the 376 patients with TB for whom data were available, 192 (51%) were screened for HIV. Of those, 33 (17%) had been tested before having received the diagnosis of TB. Multivariate analysis revealed that patients with TB who were male, aged 30 to 39, had a positive sputum smear, displayed at least 1 clinical symptom, received the TB diagnosis from a microbiologist or infectious disease specialist, or reported 1 or more HIV risk factors were more likely to be screened for HIV. CONCLUSIONS: HIV screening of patients with TB is selective, depending on both patient and physician characteristics. Physicians' awareness of recommendations needs to be increased to improve the diagnosis and treatment of TB/HIV co-infection.

Adolescent↗
PubMed1998

Persistent parasitemia after acute babesiosis.

BACKGROUND: Babesiosis, a zoonosis caused by the protozoan Babesia microti, is usually not treated when the symptoms are mild, because the parasitemia appears to be transient. However, the microscopical methods used to diagnose this infection are insensitive, and few infected people have been followed longitudinally. We compared the duration of parasitemia in people who had received specific antibabesial therapy with that in silently infected people who had not been treated. METHODS: Forty-six babesia-infected subjects were identified from 1991 through 1996 in a prospective, community-based study designed to detect episodes of illness and of seroconversion among the residents of southeastern Connecticut and Block Island, Rhode Island. Subjects with acute babesial illness were monitored every 3 months for up to 27 months by means of thin blood smears, Bab. microti polymerase-chain-reaction assays, serologic tests, and questionnaires. RESULTS: Babesial DNA persisted in the blood for a mean of 82 days in 24 infected subjects without specific symptoms who received no specific therapy. Babesial DNA persisted for 16 days in 22 acutely ill subjects who received clindamycin and quinine therapy (P=0.03), of whom 9 had side effects from the treatment. Among the subjects who did not receive specific therapy, symptoms of babesiosis persisted for a mean of 114 days in five subjects with babesial DNA present for 3 or more months and for only 15 days in seven others in whom the DNA was detectable for less than 3 months (P<0.05); one subject had recrudescent disease after two years. CONCLUSIONS: When left untreated, silent babesial infection may persist for months or even years. Although treatment with clindamycin and quinine reduces the duration of parasitemia, infection may still persist and recrudesce and side effects are common. Improved treatments are needed.

Animals↗
PubMed1996

Concurrent Lyme disease and babesiosis. Evidence for increased severity and duration of illness.

OBJECTIVE: To determine whether patients coinfected with Lyme disease and babesiosis in sites where both diseases are zoonotic experience a greater number of symptoms for a longer period of time than those with either infection alone. DESIGN: Community-based, yearly serosurvey and clinic-based cohort study. SETTING: Island community in Rhode Island and 2 Connecticut medical clinics from 1990 to 1994. STUDY PARTICIPANTS: Long-term residents of the island community and patients seeking treatment at the clinics. MAIN OUTCOME MEASURES: Seroreactivity to the agents of Lyme disease and babesiosis and number and duration of symptoms. RESULTS: Of 1156 serosurvey subjects, 97 (8.4%) were seroreactive against Lyme disease spirochete antigen, of whom 14 (14%) also were seroreactive against babesial antigen. Of 240 patients diagnosed with Lyme disease, 26 (11%) were coinfected with babesiosis. Coinfected patients experienced fatigue (P = .002), headache (P < .001), sweats (P < .001), chills (P = .03), anorexia (P = .04), emotional lability (P = .02), nausea (P = .004), conjunctivitis (P = .04), and splenomegaly (P = .01) more frequently than those with Lyme disease alone. Thirteen (50%) of 26 coinfected patients were symptomatic for 3 months or longer compared with 7 (4%) of the 184 patients with Lyme disease alone from whom follow-up data were available (P < .001). Patients coinfected with Lyme disease experienced more symptoms and a more persistent episode of illness than did those (n = 10) experiencing babesial infection alone. Circulating spirochetal DNA was detected more than 3 times as often in coinfected patients as in those with Lyme disease alone (P = .06). CONCLUSIONS: Approximately 10% of patients with Lyme disease in southern New England are coinfected with babesiosis in sites where both diseases are zoonotic. The number of symptoms and duration of illness in patients with concurrent Lyme disease and babesiosis are greater than in patients with either infection alone. In areas where both Lyme disease and babesiosis have been reported, the possibility of concomitant babesial infection should be considered when moderate to severe Lyme disease has been diagnosed.

Adolescent↗
PubMed1996

Needs assessment for an urban native HIV and AIDS prevention program.

At the request of Native community-based organizations in Montreal, a needs assessment for an HIV and AIDS education and prevention program for urban Natives was initiated. A five-session focus group concerning HIV and AIDS was attended by nine Native persons over a 2-month period. Data was collected using the guidelines of the HIV/AIDS Rapid Anthropological Assessment Procedures (AIDS RAP) developed by the Social and Behavioural Research Unit of the World Health Organization's Global Programme on AIDS. We followed these up with in-depth semistructured interviews with five different members of the Montreal Native community. The data were reviewed by a steering committee to ensure validity. Findings highlight the potential explosive route of transmission of HIV along networks of sexual interaction between persons in urban areas and then to rural partners. Maintaining control over the AIDS program planning within the community permits issues such as traditional values and healing practices to be discussed and taken into account.

Acquired Immunodeficiency Syndrome↗
PubMed1995

Factors associated with glycemia and microvascular complications among James Bay Cree Indian diabetics of Quebec.

We conducted a chart review of physician diagnosed diabetics to obtain plasma glucose levels (fasting plasma glucose and glycosylated hemoglobin) over a retrospective 30 month time span and data on the presence or absence of current renal or ophthalmic microvascular complications. Multiple logistic regression was used to determine factors associated with the presence of microvascular complications. Poor glycemic control reflected by a need of insulin therapy (odds ratio (OR) = 2.7, confidence internal (CI): 1.1, 6.7), increased serum triglyceride levels (OR = 4.5, CI: 2.0, 9.9) and duration of illness of more than five years (OR = 3.0, CI: 1.2, 7.8) were found to be associated with the presence of microangiopathies. Process of care and temporary reversion to traditional lifestyle and diet did not influence glycemic control. Our results points towards a need for an increased awareness of lipid disorders in diabetic patients and a better understanding of how social and psychological factors are related to metabolic outcomes.

Adult↗