UNITY: A low-field magnetic resonance neuroimaging initiative to characterize neurodevelopment in low and middle-income settings.

Measures of physical growth, such as weight and height have long been the predominant outcomes for monitoring child health and evaluating interventional outcomes in public health studies, including those that may impact neurodevelopment. While physical growth generally reflects overall health and nutritional status, it lacks sensitivity and specificity to brain growth and developing cognitive skills and abilities. Psychometric tools, e.g., the Bayley Scales of Infant and Toddler Development, may afford more direct assessment of cognitive development but they require language translation, cultural adaptation, and population norming. Further, they are not always reliable predictors of future outcomes when assessed within the first 12-18 months of a child's life. Neuroimaging may provide more objective, sensitive, and predictive measures of neurodevelopment but tools such as magnetic resonance (MR) imaging are not readily available in many low and middle-income countries (LMICs). MRI systems that operate at lower magnetic fields (< 100mT) may offer increased accessibility, but their use for global health studies remains nascent. The UNITY project is envisaged as a global partnership to advance neuroimaging in global health studies. Here we describe the UNITY project, its goals, methods, operating procedures, and expected outcomes in characterizing neurodevelopment in sub-Saharan Africa and South Asia.

Validation and applications of indexed aortic prosthetic valve areas calculated by Doppler echocardiography.

Doppler echocardiographic evaluation of aortic valve prostheses is based on the use of variables heretofore validated mostly for native valves. Accordingly, this study examined the validity and relative usefulness of the Doppler valve gradient and area measurements in 31 patients (mean age 69 +/- 10 years) 20 +/- 4 months after implantation of a given type of aortic bioprosthesis ranging in size from 19 to 29 mm. Valve area data obtained with both the standard and simplified continuity equations were compared with known in vitro prosthetic valve area measurements and an excellent correlation was obtained between the standard and simplified continuity equations (r = 0.98, SEE +/- 0.07 cm2, p less than 0.0005) and between in vivo and known in vitro prosthetic valve areas (r = 0.86, SEE +/- 0.16 cm2, p less than 0.0005). Peak gradient ranged from 10.8 to 75.0 mm Hg (mean 35 +/- 16) and mean gradient from 7.6 to 43.7 mm Hg (mean 20.5 +/- 9.5). The correlations between prosthetic valve gradient and in vivo area were r = -0.53, SEE +/- 14 mm Hg and r = -0.49, SEE +/- 8.63 mm Hg for peak and mean gradient, respectively. These relations were improved by indexing valve area by body surface area. The best correlations were obtained between indexed valve area and a quadratic function of the gradient (r = -0.72, SEE +/- 11.72 mm Hg and r = -0.70, SEE +/- 7.28 mm Hg for peak and mean gradient, respectively), reflecting a curvilinear relation.(ABSTRACT TRUNCATED AT 250 WORDS)

Validation and applications of mitral prosthetic valvular areas calculated by Doppler echocardiography.

Doppler echocardiography is used in the noninvasive evaluation of mitral valve prostheses using parameters heretofore validated primarily for native valves. Accordingly, this study was designed to examine the validity and relative usefulness of valve gradient and area measurements in a group of 26 patients (17 women, 9 men, mean age 62 +/- 8 years), 19 +/- 4 months after implantation of different sizes (25 to 31 mm) of a given type of bioprosthesis. Areas obtained with both the continuity equation, using stroke volume measured in the left ventricular outflow tract, and the pressure half-time method are compared to known prosthetic areas derived from an in vitro hydraulic model. Areas calculated by the continuity equation correlate well with in vitro areas (r = 0.82, standard error of the y estimate = 0.1 cm2, p less than 0.001), and are within the range of predicted in vitro values in 92% of cases. Areas derived by the pressure half-time method do not correlate with in vitro areas (r = 0.15, p greater than 0.3) or continuity equation areas (r = 0.23, p greater than 0.2), and are above the range of predicted values in 69% of cases. Correlations are also found between continuity equation areas and the peak and mean valvular gradients (r = 0.59, p less than 0.005 and r = -0.63, p less than 0.0005, respectively). Taking the effect of cardiac output on gradients into account results in projected relations between indexed prosthetic areas and the pressure gradients at rest and during exercise.(ABSTRACT TRUNCATED AT 250 WORDS)

Hepatitis A vaccination during an outbreak among gay men in Montréal, Canada, 1995-1997.

STUDY OBJECTIVE: To evaluate an intervention designed to curtail an outbreak of hepatitis A among gay men, especially the young and sexually active, by promoting their free vaccination. DESIGN: The study analysed routine passive surveillance data, carried out questionnaire and serological surveys of vaccinees, and surveys among the target population in non-clinical venues. SETTING AND INTERVENTION: 15 000 free doses of hepatitis A vaccine were made available through clinics with large gay clienteles, or at gay events, and advertised by various means, in Montréal, Canada, from August 1996 to November 1997. Simultaneous vaccination against hepatitis B (always free for gay men) was also encouraged. PARTICIPANTS: Information was obtained from persons with the disease during the epidemic period, a sample of men requesting vaccination, and five community samples of gay men. MAIN RESULTS: The outbreak involved 376 gay men and the vaccine was distributed to approximately 10 000. Vaccinees were older than cases, but had many sex partners and comprised more food handlers. Special vaccination clinics at gay events were well attended but did not reach more high risk men than regular medical venues. A self reported vaccine coverage of 49% was achieved, but 26% of vaccinees already had anti-HAV antibodies. Disease incidence declined rapidly during the campaign. CONCLUSIONS: The intervention nearly tripled self reported hepatitis A vaccine coverage but its late start precludes proving that it caused the subsequent drop in incidence. However, it also increased hepatitis B vaccination and it is believed it improved links between gay men, public health, clinicians and community groups.

HIV status of sexual partners is more important than antiretroviral treatment related perceptions for risk taking by HIV positive MSM in Montreal, Canada.

OBJECTIVE: To examine the role of antiretroviral treatment related perceptions relative to other clinical and psychosocial factors associated with sexual risk taking in HIV positive men who have sex with men (MSM). METHODS: Participants were recruited from ambulatory HIV clinics in Montreal. Information on sociodemographic factors, health status, antiretroviral treatment related perceptions, and sexual behaviours was collected using a self administered questionnaire. At-risk sexual behaviour was defined as at least one occurrence of unprotected insertive or receptive anal intercourse in the past 6 months. Multivariate logistic regression was performed to evaluate the associations between at-risk sexual behaviour and covariates. RESULTS: 346 subjects participated in the study. Overall, 34% of subjects were considered at risk; 43% of sexually active subjects (n=274). At-risk sexual behaviour was associated with two antiretroviral treatment related perceptions: (1) taking antiretroviral treatment reduces the risk of transmitting HIV (adjusted odds ratio (OR), 2.10; 95% confidence interval (CI), 1.16 to 3.80); and (2) there is less safer sex practised by MSM because of HIV treatment advances (OR, 1.82; CI, 1.14 to 2.90). Other factors, however, were more strongly associated with risk. These were: (1) safer sex fatigue (OR, 3.23; CI, 1.81 to 5.78); (2) use of "poppers" during sexual intercourse (OR, 6.28; CI, 2.43 to 16.21); and (3) reporting a greater proportion of HIV positive anal sex partners, compared with reporting no HIV positive anal sex partners: (a) <50% HIV positive (OR, 16.79; CI, 4.70 to 59.98); (b) > or =50% HIV positive (OR, 67.67; CI, 15.43 to 296.90). CONCLUSION: Despite much emphasis on HIV treatment related beliefs as an explanation for sexual risk taking in MSM, this concern may play a relatively minor part in the negotiation of risk by HIV positive MSM. Serosorting, safer sex fatigue, and the use of poppers appear to be more important considerations in understanding the sexual risk behaviours of HIV positive MSM.

Practice settings and prescribing profiles: the simulation of tension headaches to general practitioners working in different practice settings in the Montreal area.

The purpose of this study was to determine whether physicians practicing in one type of setting manage a medical problem differently than those practicing in another type of setting. The investigation took the form of presenting physicians with a simulated case of tension headache with a history going back three years, for which diazepam had been taken daily for the past year. Four simulated patients (aged 20-23) visited a stratified random sample of 111 general practitioners practicing in health centers funded by government (CLSCs) and in private group practice clinics in the Montreal area. Fifty-one per cent of group practice physicians recommended therapy rated as "inadequate" compared to 25 per cent in CLSCs; in addition, the data show significant differences between CLSC and group practice physicians in performing various aspects of the clinical examination. Alternative explanations for the observed differences are discussed.

[Potentially inappropriate benzodiazepine prescriptions in elderly nursing home patients]. / Prescriptions potentiellement inappropriées de benzodiazépines chez les personnes âgées en centre d'accueil.

OBJECTIVE: To evaluate the incidence of benzodiazepine overprescription as a cause of benzodiazepine overuse in nursing homes. DESIGN AND SETTING: Physicians were asked to complete a multiple-choice questionnaire for patients receiving at least one benzodiazepine and to indicate the reason for the prescription. To control for social desirability bias, two fictitious cases were submitted to each physician. Overprescription was defined as a prescription for benzodiazepine that differed from the indications given in the product monograph. PARTICIPANTS: Family physicians of patients living in three nursing homes in the Quebec City area were solicited by mail to take part in the survey. RESULTS: Fifteen physicians treating 152 patients, whose average age was 82.1 years (range 50 to 100 years), agreed to take part in the study. It was found that 77.1% of the patients had been taking a benzodiazepine for more than a year. For 14.5% of the prescriptions, there was no official indication. The reasons most frequently cited for these prescriptions were that the physician was renewing a prescription given before he took charge of the patient, the patient's refusal to discontinue use of the medication, pressure from the nursing staff, and the fact that the patient was causing a disturbance. In 4% of the cases (6 answers), the physician acknowledged that there was no indication for prescribing a benzodiazepine. CONCLUSION: This study shows that, in 14.5% of cases, overprescription could be a cause of benzodiazepine overuse in nursing homes.