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Biomedical subjects

E Roy

Publications and source records attributed to E Roy.

At least 19 recordsLinked to original sources
PubMed2005

[Pulmonary bilharziosis due to Schistosoma haematobium: pitfalls of species diagnosis. A case report from Libreville, Gabon].

The purpose of this report is to describe a case of pulmonary schistosomiasis treated at la Fondation Jeanne Ebori in Libreville, Gabon. This case is exceptional due to the rarity of the disease and the schistosomiasis agent involved. The patient was a 47-year-old woman who presented with recurrent right-sided pneumonia 6 months after initial hospitalization and nonspecific antimicrobial therapy. Her general status was altered by hyperthermia, right chest pain, and repetitive bouts of hemoptysia. Because etiological diagnosis could not be achieved and clinical condition was deteriorating, the decision was taken to perform exploratory thoracotomy. Based on operative findings, medial and lower lobectomy was performed. Histological examination demonstrated granulomatous inflammatory lesions due to bilharziosis. Infection was attributed to Schistosoma haematobium that is the most common agent in pulmonary localizations. However Ziehl coloration raised the possibility of involvement of Schistosoma intercalatum that has never been observed in the lung and of a hybrid species. Natural hybridization between S. haematobium and S. intercalatum and the presence of active transmission of the Schistosoma hybrid has been suspected in Gabon.

Animals↗
PubMed2004

Characteristics of adolescent street youth with a history of pregnancy.

UNLABELLED: This study examines characteristics of adolescent street youth with histories of pregnancy and documents important factors that merit consideration when providing global sexual health care. STUDY OBJECTIVE: To determine social and behavioral factors associated with a history of pregnancy among adolescent street youth. DESIGN, SETTING, PARTICIPANTS: In a prospective cohort study, female adolescent street youth (14-19 years) ever pregnant (AEP) were compared with adolescents never pregnant (ANP) using data from baseline questionnaires. RESULTS: Among the 225 participants, 41.8% were ever pregnant. Both groups were similar with respect to age (mean 17.8 years) and other socio-economic characteristics. However, AEP were more likely to have been kicked out of home (62.8% vs. 47.3%, P=0.022) and to have run away (78.7% vs. 64.9%, P=0.025) and were homeless younger (mean age: 13.9 vs. 14.7 years, P=0.011) and since a longer period (mean: 4.0 vs. 3.0 years, P=0.001). Both groups had problematic alcohol and drug use: 31.3% had a CAGE score >2; 72.2% had a DAST score >6. Almost half (44.0%) had ever injected drugs and AEP were younger at initiation into drug injection (15.2 years vs. 16.0 years, P=0.049). More AEP had experienced intra-familial or extra-familial sexual abuse (71.3% vs. 56.5%, P=0.024), and had had more than one abuser (71.6% vs. 50.0%, P=0.009). Among those abused by family members, abuse occurred at an earlier age for AEP (mean age: 7.4 vs. 8.9 years, P=0.090) and more AEP reported severe abuse: vaginal penetration (62.2% vs. 26.7%, P=0.004) and anal penetration (29.7% vs. 3.3%, P=0.005). CONCLUSIONS: Histories of severe sexual abuse and early injection drug use are extremely frequent in ever pregnant street adolescents. These factors need to be addressed when planning global health care and sexual health education.

Adolescent↗
PubMed2004

HIV risk profile of male street youth involved in survival sex.

OBJECTIVES: To compare HIV risk factors of male street youth involved in survival sex with those of their never involved peers and to describe the sexual activities of the involved youths. METHODS: From 2001 to 2003, street youth aged 14-23 years were recruited from street youth agencies in Montreal, Canada. Information was collected on sociodemographic characteristics, substance use, and sexual behaviours. Involvement in survival sex was defined as having ever exchanged sex for money, gifts, drugs, shelter, or other needs. Logistic regression was used to identify HIV risk factors associated with involvement in survival sex. RESULTS: Among the 542 male participants recruited, 27.7% reported involvement in survival sex. HIV risk factors independently associated with such involvement were injection drug using partners (modulated by length of homelessness), unprotected oral sex with male partners, steroid injection, history of sexual abuse, and drug injection. Among involved youths, 32.0% had only female clients, 41.3% only male clients, and 26.7% had clients of both sexes. Unprotected sexual activities were common with clients. However, even more risks were taken with non-commercial sexual partners. CONCLUSIONS: Male street youth involved in survival sex are at higher risk for HIV than their non-involved peers not only because of their unprotected commercial sexual activities. They have multiple other HIV risks related to non-commercial sexual activities, drug injection, and sexual abuse. All these risks need to be addressed when providing sexual health interventions for this population.

Adolescent↗
PubMed2002

Quantitative comparison of radial cell columns in children with Down's syndrome and controls.

No one has examined the configuration of the minicolumns in Down's syndrome (DS) brains even though these are a basic functional unit of the cortex. In the present study, the authors used computerized imaging to examine minicolumns in the posterior superior temporal gyrus in both the brains of patients with DS and normal controls. They compared the brains of children aged 4 and 6 years with those of adults for both people with DS and the normal population. Columns in the brains of two DS children aged 4 and 6 years were almost the same size as those of the adults with DS. The neuropil space in the periphery of the columns was also considerably wider. In contrast, minicolumns in aged-matched control children were smaller, both relatively and absolutely, when compared to the mean size of adult columns. The size of the minicolumns in the normal children apparently corresponded to the overall brain size, whereas the large columns in children with DS appeared to be independent of brain size, at least in area Tpt. This seems to reflect a rapid ageing process that is striking when compared to normal controls. Columns in adults with DS were large and less cell dense, while brain volumes were significantly smaller than in controls. This combination suggests reduced neuronal complexity based on a decrease in processing units, which supports previous findings of decreased cell numbers and synaptic diminution in DS brains.

Adolescent↗
PubMed2002

Risk behaviours and prevalence of Chlamydia trachomatis and Neisseria gonorrhoeae genital infections among Montreal street youth.

We estimated the prevalence of Chlamydia trachomatis and Neisseria gonorrhoeae genital tract infections among 302 Montreal street youth (223 boys) and identified associated risk factors. Study participants, 14-25 years old (average 20.9 years), meeting specific criteria for homelessness, were recruited in street youth agencies. Participation included a structured interview and provision of a urine specimen. Among sexually active youth, (n = 300) 30.0% had more than five heterosexual partners and 13.0% had at least one homosexual partner (last year), 10.7% had received money in exchange for sex (last six months) and 47.0% reported sexual relations resulting in pregnancy (lifetime). Among all youths, 82.1% had used at least one type of illicit drug, and 30.1% injected drugs at least once (last six months). The prevalence of C. trachomatis infection was 6.6% (95% CI 4.1-10.0%). Prevalence did not vary significantly by sex, age or any other variable, except history of pregnancy (10.4% among youth with history of pregnancy vs 3.6% among others, P = 0.02). No cases of N. gonorrhoeae infection were found.

Adolescent↗
PubMed2001

Risk factors for hepatitis C virus infection among street youths.

BACKGROUND: The relative contributions to risk of hepatitis C virus (HCV) infection resulting from unsafe sexual behaviours and exposures to blood (e.g., tattooing, body piercing and injection drug use) among youths at risk are not well known. We interviewed street youths about risk factors for HCV infection and documented their HCV antibody status. METHODS: From December 1995 to September 1996 we recruited 437 youths aged 14 to 25 years who met specific criteria for itinerancy. Data on sociodemographic characteristics and lifetime risk factors were obtained during a structured interview, and a venous blood sample was taken for HCV antibody testing. RESULTS: Many of the subjects reported behaviours that put them at risk for blood-borne diseases: 45.8% had injected drugs, 56.5% had at least 1 tattoo, and 78.3% had body piercing. The overall prevalence of HCV infection was 12.6% (95% confidence interval [CI] 9.7%-15.9%). In a multivariate logistic regression analysis, injecting drugs (adjusted odds ratio [OR] 28.4 [95% CI 6.6-121.4]), being over 18 years of age (adjusted OR 3.3 [95% CI 1.6-7.0]) and using crack cocaine (adjusted OR 2.3 [95% CI 1.0-5.3]) were independent risk factors for HCV infection. Having more than 1 tattoo (adjusted OR 1.8 [95% CI 0.95-3.6]) was marginally associated with HCV infection, and body piercing was not. INTERPRETATION: Drug injection was the factor most strongly associated with HCV infection among street youths. Given that injection drug users are the driving force of the HCV infection epidemic in Canada, increased intervention efforts to prevent initiation of drug injection are urgently needed to curb the epidemic.

Adolescent↗
PubMed2001

Morphological differences between minicolumns in human and nonhuman primate cortex.

Our study performed a quantitative investigation of minicolumns in the planum temporale (PT) of human, chimpanzee, and rhesus monkey brains. This analysis distinguished minicolumns in the human cortex from those of the other nonhuman primates. Human cell columns are larger, contain more neuropil space, and pack more cells into the core area of the column than those of the other primates tested. Because the minicolumn is a basic anatomical and functional unit of the cortex, this strong evidence showed reorganization in this area of the human brain. The relationship between the minicolumn and cortical volume is also discussed.

Adaptation, Physiological↗
PubMed2001

New method of cardiac output measurement using ultrasound velocity dilution in rats.

The aim of this study was to validate a new technique for the measurement of cardiac output (CO) based on ultrasound and dilution (COUD) in anesthetized rats. A transit time ultrasound (TTU) probe was placed around the rat carotid artery, and ultrasound velocity dilution curves were generated on intravenous injections of saline. CO by COUD were calculated from the dilution curves for normal and portal hypertensive rats in which CO was known to be increased. COUD was compared with the radiolabeled microsphere method and with direct aortic TTU flowmetry for baseline CO and drug-induced CO variations. CO in direct aortic TTU flowmetry was the ascending aorta blood flow measured directly by TTU probe (normal use of TTU flowmetry). The reproducibility of COUD within the same animal was also determined under baseline conditions. COUD detected the known CO increase in portal hypertensive rats compared with normal rats. CO values by COUD were correlated with those provided by microsphere technique or direct aortic TTU flowmetry (adjusted r = 0.76, P < 10(-4) and r = 0.79, P < 0.05, respectively). Baseline CO values and terlipressin-induced CO variations were detected by COUD and the other techniques. Intra- and interobserver agreements for COUD were excellent (intraclass r = 0.99 and 0.98, respectively). COUD was reproducible at least 10 times in 20 min. COUD is an accurate and reproducible method providing low-cost, repetitive CO measurements without open-chest surgery. It can be used in rats as an alternative to the microsphere method and to direct aortic flowmetry.

Animals↗
PubMed2001

Lateralization of minicolumns in human planum temporale is absent in nonhuman primate cortex.

Gross analyses of large brain areas, as in MRI studies of macroanatomical structures, average subtle alterations in small regions, inadvertently missing significant anomalies. We developed a computerized imaging program to microscopically examine minicolumns and used it to study Nissl-stained slides of normal human, chimpanzee, and rhesus monkey brains in a region of the planum temporale. With this method, we measured the width of cell columns, the peripheral neuropil space, the spacing density of neurons within columns, and the Gray Level index per minicolumn. Only human brain tissue revealed robust asymmetry in two aspects of minicolumn morphology: wider columns and more neuropil space on the left side. This asymmetry was absent in chimpanzee and rhesus monkey brains.

Algorithms↗
PubMed2001

Electrochemical synthesis of antimony nanowires and analysis of diffusion layers.

Synthesis of an array of antimony nanowires was performed by electrodeposition within a porous polycarbonate membrane. The sizes of pores range from 30 to 400 nm in diameter and their densities vary from 2 x 10(+6) to 2 x 10(+9) pores/cm2. To obtain optimal conditions for nanowire preparation, plating behavior was investigated by a potentiostatic method with two types (continued or pulsed) of polarization. The chronoamperometry revealed that responses depend on the type of polarization and on the pore density of the membrane. With high-density membranes, the diffusion layers of each individual pore immediately overlap when they reach the external part of the membrane. This leads to an abrupt decrease of current intensity. This phenomenon is not observed with low-density membranes because of the greater distance between pores. This mechanism, which was investigated in antimony nanowire plating, is applicable to electrodeposition of other types of materials.

Antimony↗
PubMed2000

Quantitative analysis of cell columns in the cerebral cortex.

We present a quantified imaging method that describes the cell column in mammalian cortex. The minicolumn is an ideal template with which to examine cortical organization because it is a basic unit of function, complete in itself, which interacts with adjacent and distance columns to form more complex levels of organization. The subtle details of columnar anatomy should reflect physiological changes that have occurred in evolution as well as those that might be caused by pathologies in the brain. In this semiautomatic method, images of Nissl-stained tissue are digitized or scanned into a computer imaging system. The software detects the presence of cell columns and describes details of their morphology and of the surrounding space. Columns are detected automatically on the basis of cell-poor and cell-rich areas using a Gaussian distribution. A line is fit to the cell centers by least squares analysis. The line becomes the center of the column from which the precise location of every cell can be measured. On this basis several algorithms describe the distribution of cells from the center line and in relation to the available surrounding space. Other algorithms use cluster analyses to determine the spatial orientation of every column.

Algorithms↗
PubMed2000

Comparison of time-frequency estimators for peripheral embolus detection.

Recently, a time-frequency processing of peripheral arterial Doppler signals, based on the spectrogram, was proposed to detect automatically high-intensity transient signal. Three time-frequency representations, the smooth-pseudo-Wigner-Ville, the Choï-Williams and the cone-kernel distributions were compared with the spectrogram, following the detection scheme previously reported. The results showed that the spectrogram provided the best compromises between false-detection and no-detection compared with the other time-frequency representations.

Embolism↗
PubMed2000

Stability study of W/O/W viscosified multiple emulsions.

Stable multiple emulsions with a small proportion of primary emulsion containing different viscosifying agents in the outer aqueous phase were formulated. The multiple systems were assessed by evaluating several parameters, such as the macroscopic aspect, droplet size, release rate, and accelerated stability under elevated temperatures. The effect of different viscosifying agents at different concentrations on the stability and the multiplicity of the multiple emulsions was examined. The viscosity increased by increasing the concentration of the viscosifying agents. It also appeared that the viscosifying agents increased the temperature stability of the multiple emulsions. As a result, the formulation viscosified with Klucel was more stable, while the one prepared with carbomer viscosified the outer phase at much lower concentrations with much better skin feel.

Chemistry, Pharmaceutical↗
PubMed2000

Prevalence of HIV infection and risk behaviours among Montreal street youth.

We aim to estimate HIV prevalence and associated risk factors among street youth in Montreal, Canada. We conducted a one-year cross-sectional anonymous study in 1995. We recruited youth aged 13-25 years meeting specific criteria for itinerancy through the 20 major Montreal street youth agencies. Participation included a structured interview and provision of an oral specimen for HIV testing. Among the 909 subjects studied, 99.3% had been sexually active, 25.9% had exchanged sex for money, gifts, drugs, a place to sleep, or other things; 31.8% reported anal sex; and 36.4% reported having ever injected drugs. Overall, HIV prevalence was 1.9% (1.1% in girls and 2.2% in boys). Multivariate logistic regression showed that being over 20 years of age (adjusted odds ratio (AOR) 7.09), having injected drugs (AOR 4.48), having engaged in prostitution (AOR 3.32), and being born outside Canada (AOR 4.41) were all independently associated with HIV infection.

Adolescent↗
PubMed1999

Hepatitis B virus infection among street youths in Montreal.

BACKGROUND: Street youths are at high risk for many health problems, including sexually transmitted diseases and bloodborne infections. The authors conducted a cross-sectional anonymous study from December 1995 to September 1996 involving street youths in Montreal to estimate the prevalence of risk behaviours for hepatitis B virus (HBV) infection and of markers of past and present HBV infection. METHODS: Participants were 437 youths aged 14 to 25 meeting specific criteria for itinerancy who were recruited in collaboration with the 20 major street youth agencies in Montreal. Sociodemographic and lifetime risk factor data were obtained during a structured interview, and a blood sample was taken to test for HBV markers (hepatitis B surface antigen and antibodies to the hepatitis B core antigen). Univariate analyses and multivariate logistic regressions were conducted. RESULTS: The mean age of the subjects was 19.5 years; 69.3% (303/437) were males. Many subjects had high-risk behaviours: 45.8% (200/437) had injected drugs, 24.5% (107/436) had engaged in prostitution, and 8.7% (38/437) reported having a sexual partner with a history of unspecified hepatitis. The prevalence rate for one or both HBV markers was 9.2% (40/434) (95% confidence interval [CI] 6.7%-12.3%). Multivariate logistic regression analysis showed that being over 18 years of age (adjusted odds ratio [OR] 4.5, 95% CI 1.8-11.7), having injected drugs (adjusted OR 3.5, 95% CI 1.5-8.3) and having had a sexual partner who had unspecified hepatitis (adjusted OR 3.2, 95% CI 1.3-7.5) were all associated with HBV infection. INTERPRETATION: Street youths are at high risk for HBV infection. Early and complete HBV vaccination among this vulnerable population is urgently needed.

Adolescent↗
PubMed1999

Spectrogram analysis of arterial Doppler signals for off-line automated hits detection.

Recently, a time processing of arterial Doppler signals was proposed to detect automatically high-intensity transient signals (HITS). This technique provided satisfactory detection results, but was not always constantly accurate, particularly with high-resistance blood velocity profiles. A time-frequency processing, based on the spectrogram, is presented to detect the presence of emboli in the arterial Doppler signals. The method uses the narrow-band hypothesis and extracts the detection criterion from the time-frequency representation (TFR). A first database of 560 peripheral arterial Doppler HITS was created to study microemboli and to define the normal limits to be used in our method. A threshold was experimentally defined using this database, and then applied to 38 recordings from 12 patients. Using another database, 6 human expert Doppler users reported 140, 176, 155, 161, 161 and 146 HITS, corresponding to a total of 197 different observed HITS. When an event was detected by at least 6, 5, 4, 3, 2 and 1 of the observers, sensitivity of the automatic detection was 93.9, 91.7, 89.6, 88.7, 84.7 and 73.1%, respectively. The sensitivity of our automatic detection is, thus, highly associated with the number of observers in agreement. A preliminary experiment has been performed to test the method in the case of long recording duration. In 15 patients, 6 h 24 min of recordings have been analyzed. The proposed automated processing provided an overall sensibility of 91.5%. The present work shows that this detection scheme preserves good sensibility and improves the positive predictive value compared with the time-processing recently proposed.

Arteries↗