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Biomedical subjects

M Lemay

Publications and source records attributed to M Lemay.

At least 19 recordsLinked to original sources
PubMed2005

Sensorimotor mapping affects movement correction deficits in early Huntington's disease.

Huntington's disease (HD) is associated with early voluntary movement problems linked to striatal dysfunction. In pointing movements, HD increases the irregularity of the terminal part of movements, suggesting a dysfunction in error feedback control. We tested this hypothesis in movements requiring continuous feedback control. Patients in the early stages of HD and controls traced as fast and accurately as possible circles within a 5-mm annulus on a digitizing tablet when visual feedback of the hand and the circle was direct or indirect (through a monitor). Patients deviated more often from the annulus and showed larger corrections toward the circle than controls when using indirect visual feedback but not with direct visual feedback. When velocity requirements were removed, patients showed little change in these control problems. These results suggest that HD does not affect error feedback control in all movements and that the striatal contribution to voluntary movement is sensitive to sensorimotor mapping.

Adult↗
PubMed2001

A randomized clinical trial of care for women with preterm labour: home management versus hospital management.

BACKGROUND: Preterm labour occurs in about 10% of all pregnancies and is the most important cause of premature birth. Women with preterm labour are admitted to hospital to have the contractions stopped. Thereafter, many women remain in hospital until delivery. We conducted a randomized clinical trial to compare hospital care with home care of women who had been admitted to hospital for preterm labour. METHODS: After they had received treatment for an acute episode of premature labour, women at 2 regional perinatal centres associated with teaching hospitals were randomly assigned to home care or hospital care. Eligible women (n = 250) were aged 18 years or older, lived within 50 km of the hospital, had a gestational age between 20 and 35 weeks, had no prior preterm delivery and were experiencing their first episode of preterm labour and first admission to hospital for preterm labour. Analysis was by intention to treat. RESULTS: There were no significant differences between the 2 groups in mean gestational age at delivery (home: 37.52 weeks, hospital: 37.50 weeks) or in mean birth weight (home: 2974 g, hospital: 3020 g). There were no significant differences between the 2 groups with respect to the proportions of babies born before term or the mean duration of neonatal hospital stay, neonatal intensive care unit stay and intermediate care nursery stay. The mean duration of the first stay in hospital for the women in the home group (3.8 days) was significantly shorter than the mean duration for women in the hospital group (6.1 days). In addition, the mean duration of all maternal stays in hospital was significantly shorter for the women in the home group (3.7 days) than in the hospital group (5.0 days). INTERPRETATION: Home care management is an efficient and acceptable alternative to hospital care for women experiencing preterm labour.

Adolescent↗
PubMed2001

A distance effect in a manual aiming task to remembered targets: a test of three hypotheses.

It has been noted that manual aiming error and variability when pointing to remembered targets increase as a function of target eccentricity. In the present study we evaluated which one of three hypotheses (target localization, motor, or movement duration) best explains this 'distance effect'. In experiment 1, older and younger participants aimed with their unseen hand at the remembered location of targets distributed between 129 and 309 mm from the starting base. Target presentation time was of either 50 or 500 ms and aiming movements could be initiated following either a 100- or a 10,000-ms recall delay. Participants had either no constraints concerning movement time or were asked to reach the near target in a longer movement time than the farther targets. The results revealed a significant distance effect when no time constraints were imposed but showed a significantly reversed distance effect when the instructions were to reach the near targets in a longer movement time than the far targets. The same results were obtained regardless of target presentation time, recall delay, or age of the participants. These results supported a movement duration interpretation of the distance effect. In experiment 2, a distance effect was replicated when pointing with one's unseen hand toward a remembered target but did not take place when pointing to visible targets. Taken together these results suggest that prolonged movement execution interferes with the stored egocentric target representation.

Adult↗
PubMed1999

Mitochondrial peripheral-type benzodiazepine receptor expression. Correlation with gonadotropin-releasing hormone (GnRH) agonist-induced apoptosis in the corpus luteum.

We have demonstrated that continuous administration of a gonadotropin-releasing hormone agonist (GnRH-Ag) decreases the expression of the mitochondrial peripheral-type benzodiazepine receptor (PBR) and increases the rate of DNA degradation in a time-dependent manner in the corpora lutea of pregnant rats. In the present study, we show in situ the GnRH-Ag-induced DNA fragmentation and correlate the increase of the rate of DNA degradation with the decrease in mitochondrial PBR ligand binding (r = 0.89). The GnRH-Ag-induced decrease in the 18-kDa PBR protein also correlated with the reduction in the Bcl-X(L), but not Bcl-2 (cell survival), gene product levels and the increase in the Bax (cell death) gene product expression in the luteal mitochondrial preparations. Considering the function of PBR in cholesterol uptake and intramitochondrial movement, we propose that decreased PBR expression may lead to reduced levels of mitochondrial membrane cholesterol, which, together with the ability of Bcl-X(L) and Bax to form ion channels, produces breaks in the outer membranes allowing the exit of cytochrome c, thus triggering apoptosis. Alternatively, PBR may exert an as yet unidentified anti-apoptotic function.

Animals↗
PubMed1999

Juvenile xanthogranuloma presenting as obstructive jaundice.

The authors report the case of a 9-month-old infant presenting with obstructive jaundice. Preoperative investigation findings showed distension of the extrahepatic biliary tract. Urine analysis result was positive for cytomegalovirus. At laparotomy, a 1-cm round mass was found within the head of the pancreas, near its upper border and in the course of the common bile duct. Findings on frozen sections could not rule out a malignant process and an hepaticoduodenostomy was constructed. Final diagnosis was juvenile xanthogranuloma. An association between cytomegalovirus and juvenile xanthogranuloma has been reported previously in the literature.

Cholecystectomy↗
PubMed1999

Increased cortisol levels and impaired cognition in human aging: implication for depression and dementia in later life.

Perhaps the most prominent feature of human aging is the variability in decline of intellectual processes. Although many research avenues have been used to study the origin of such an increased variability with aging, new studies show that some biological factors may be associated with normal and pathological cognitive aging. One biological parameter that came under scrutiny in the past few years is the hypothalamic-pituitary-adrenal (HPA) axis, an endocrine closed-loop system controlling the secretion of stress hormones (glucocorticoids). In this review, we summarize data obtained in both animals and humans suggesting that cumulative exposure to high levels of glucocorticoids can be particularly detrimental for the aged hippocampus, a brain structure involved in learning and memory in both animals and humans. We then analyze the implication of these data for the study of dementia and depression in later life, two disorders characterized by increased glucocorticoid secretion in a significant proportion of patients. Finally, we suggest various factors that could explain the development of glucocorticoid hypersecretion in later life.

Aging↗
PubMed1999

Detection of DNA damage and identification of UV-induced photoproducts using the CometAssay kit.

We introduce the first commercially available comet assay for the detection and quantification of DNA damage in individual eukaryotic cells. The major difficulty of the comet assay is the preparation of the slides needed to immobilize the samples throughout the lysis and electrophoretic procedures. The CometAssay kit uses a proprietary technology to precoat glass microscope slides to allow direct application of the agarose embedded sample without any additional slide treatment. In this report, we discuss the detection of DNA damage in individual cells exposed to ultraviolet irradiation using the new CometSlides and their cost compared to traditional slides.

Animals↗
PubMed1998

Cycling activity of benign prostatic epithelial cells during long-term androgen blockade: evidence for self-renewal of luminal cells.

Combined androgen blockade (CAB) therapy (LHRH agonist and flutamide) for 6 months leads to marked regressive changes of the prostate gland. This is associated with a reduction in the ratio of luminal to basal cells in the peripheral zone (PZ) in hyperplastic glands of the transitional zone (TZ). To examine the cycling activity of luminal and basal cells, double immunostaining was performed. For precise definition of basal cells, the basal cell-specific antibody 34 beta E12 was used, while cycling cells were identified by the MIB-1 antibody. In 6-month-treated specimens, the fraction of cycling luminal cells increased from 0.3 to 2.5 per cent in the PZ and from 0.2 to 3.9 per cent in the TZ. This was associated with an inversion of the ratio of MIB-1-labelled luminal to basal cells, with values of 5.7:1 (PZ) and 3.9:1 (TZ), compared with 1:4 (PZ) and 1:5 (TZ) in untreated specimens. The predominance continued for at least 11 years of CAB. The findings strongly suggest that luminal cells are capable of self-renewal under conditions of low androgen levels. The substantial decrease of prostatic volume on long-term CAB implies that cell loss outweighs cell proliferation.

Androgen Antagonists↗
PubMed1997

Beneficial effect of combination hormonal therapy administered prior and following external beam radiation therapy in localized prostate cancer.

PURPOSE: The aim of the present study is to investigate whether combined androgen blockade associated with radiation therapy for localized prostate cancer decreases at 12 and 24 months the rate of positive follow-up biopsies and serum PSA compared to radiation therapy alone. This is the report of an interim analysis. METHODS AND MATERIALS: One hundred and twenty patients with clinical Stage B1-T2a, B2-T2b/T2c, and C-T3/T4, adenocarcinoma of the prostate were entered in a prospective randomized study. After written informed consent, the subjects were randomly allocated between external beam radiation therapy (EBRT) alone (group 1), 3 months of neoadjuvant combination therapy (LHRH-agonist + Flutamide) prior to EBRT (group 2), and a third group receiving combination therapy 3 months before, during, and 6 months after EBRT. There is no significant difference between the three groups concerning age, stage of disease, grade of tumor, and pretreatment PSA levels. Control transrectal ultrasound (TRUS)-guided needle biopsies (one core was taken from the initial cancer site regardless of the presence or absence of TRUS abnormalities) were done 12 and 24 months after the end of EBRT. Serum PSA measurements were done on schedule visits. RESULTS: Ninety-two and 68 patients underwent biopsies at 12 and 24 months, respectively, after the end of radiation therapy. While 62% of control patients at 12 months in Group 1 disclosed residual neoplasm, only 30% and 4% showed residual disease in groups 2 and 3, respectively (p = 0.00005). When looking at 24 months, 65, 28, and 5% showed residual cancer for groups 1, 2, and 3, respectively (p = 0.00001). The PSA measurements indicate also at 12 months a difference between the three groups (p < 0.0001), except at 24 months, the difference between the group 2 and 3 is no longer significant. CONCLUSION: The preliminary analysis of this clinical trial indicates that patients treated with radiation therapy alone show a significantly higher rate of positive biopsies at 12 and 24 months after the end of radiation therapy as compared with those treated with total antiandrogen blockade (TAB) and radiation therapy. When analyzing the median PSA serum levels, we found the same advantage at 12 months, but, at the time of the analysis at 24 months, the PSA levels are not different between groups 2 and 3.

Aged↗
PubMed1997

Placenta percreta: balloon occlusion and embolization of the internal iliac arteries to reduce intraoperative blood losses.

Obstetric hemorrhage is still a potential cause of maternal mortality and morbidity. Angiographic embolization techniques have been described in cases of postcesarean bleeding, vaginal wall hematomas, cervical ectopic pregnancies, and postpartum bleeding to control persistent bleeding from pelvic vessels. We describe two cases of pregnancy complicated with placenta percreta. Balloon occlusion and embolization of the hypogastric arteries were performed during the cesarean section and hysterectomy, resulting in a remarkable reduction in intraoperative blood loss. Balloon occlusion and embolization of the internal iliac arteries significantly reduce intraoperative blood losses.

Adult↗
PubMed1997

Neoadjuvant hormonal therapy: the Canadian experience.

OBJECTIVE: To assess the effect of neoadjuvant combination therapy with the antiandrogen flutamide and a luteinizing-hormone-releasing hormone (LHRH) agonist administered for 3 months before radical prostatectomy, compared with surgery alone in early stage prostate cancer on histopathologic findings at surgery and serum prostate-specific antigen (PSA). METHODS: A sample of 161 randomly screened patients diagnosed as having stage B (134 patients) or C (27 patients) prostate cancer were randomly assigned to radical prostatectomy alone or to 3 months of neoadjuvant combination therapy with the antiandrogen flutamide and an LHRH agonist before radical prostatectomy. RESULTS: Neoadjuvant combination therapy before radical prostatectomy decreased cancer-positive surgical margins from 33.8% in the control group to only 7.8%, thus leaving 92.2% of patients with negative margins at surgery. A net 54% improvement of staging was observed in favor of combination therapy. Organ-confined disease, on the other hand, increased from 49.3% to 77.8% of patients after 3 months of combination therapy, for a 57.8% increase in the incidence of organ-confined disease. No cancer was found in 6 (6.7%) prostatectomy specimens from the treated group. A close correlation was found between serum PSA at diagnosis and the stage of the disease at surgery. Upstaging increased from 30% at serum PSA values of 0 to 3.0 ng/mL up to 100% at serum PSA values above 15 ng/mL. CONCLUSIONS: Although long-term follow-up of these patients is required to determine the impact on survival, the marked influence of neoadjuvant combination therapy on the stage of the disease suggests the possibility of a major improvement in the morbidity and mortality from prostate cancer.

Adenocarcinoma↗
PubMed1997

Speech perception abilities of adult and pediatric Nucleus implant recipients using the Spectral Peak (SPEAK) coding strategy.

A series of 73 postlinguistically deafened adults and 34 prelinguistically deafened children were evaluated with the Spectral Peak (SPEAK) coding strategy of the Nucleus 22-channel cochlear implant. The adults who received consecutive implants demonstrated rapid acquisition of open-set speech recognition skills in the initial postoperative period. Group mean sentence recognition improved to 53.5% (n = 52) after 2 weeks, 62.1% (n = 55) after 1 month, 69.8% (n = 57) after 3 months, and 74.4% (n = 42) after 6 months of use. At the 6-month evaluation interval, 43% of subjects scored greater than 90% on sound-alone sentence recognition in quiet and only one patient (2.4%) scored less than 10%. Mean monosyllabic word recognition was 35.6% after 6 months of use. The 34 prelinguistically deafened children were converted from the Multipeak strategy to Spectral Peak strategy at four large pediatric implant centers. After 6 months of using the new coding strategy, the children demonstrated significant improvements in their speech perception abilities.

Adult↗
PubMed1996

Kallikreins expression in a mature cystic ovarian teratoma.

We report an example of benign cystic ovarian teratoma that was incidentally discovered in a nulliparous 24-year-old woman taking contraceptive pills. Histological examination of the cyst revealed the presence of prostatelike tissue in association with a wide variety of other tissues. The use of highly specific monoclonal antibodies developed against the two prostate-specific kallikreins (hK2 and hK3) in humans allowed the demonstration that the multiple islets of epithelial cells were prostatic tissue in nature and that only part of these cells had conserved their intrinsic property of producing kallikreins.

Adult↗
PubMed1996

Diagnosis of advanced or noncurable prostate cancer can be practically eliminated by prostate-specific antigen.

OBJECTIVES: To determine the percentage of localized and potentially curable prostate cancers diagnosed at follow-up screening visits compared with the first screening visit. METHODS: Within the context of a prospective screening study performed in randomly chosen men aged between 45 and 80 years, up to 6-year follow-up screening visits have been performed with serum prostate-specific antigen (PSA) measurement and digital rectal examination (DRE) followed by transrectal ultrasonography of the prostate when PSA or DRE is abnormal. RESULTS: Of the 117 prostate cancers diagnosed at 14,554 annual follow-up visits, only 1 cancer (0.9%) was metastatic compared with 8% (26/322) at 8029 first visits. Moreover, 97% of the cancers detected at follow-up visits could be identified by PSA alone compared with 86% at first visit. The incidence of 0.8% per year during 15 years of screening between the ages of 55 and 70 years would diagnose localized prostate cancer in 12% of the population, a value not too different from the 10% diagnosed with prostate cancer during life-time in the absence of screening. CONCLUSIONS: The present data show that annual screening with PSA diagnoses clinically localized prostate cancer in more than 95% of cases, thus almost completely eliminating the diagnosis of metastatic prostate cancer. Moreover, the number of prostate cancers diagnosed is not significantly increased by screening.

Aged↗
PubMed1996

Tendon transfers and functional electrical stimulation for restoration of hand function in spinal cord injury.

Spinal cord injury at the C5 and C6 level results in loss of hand function. Electrical stimulation of paralyzed muscles is one approach that has demonstrated significant capacity for restoring grasp and release function. One potential limitation of this approach is that key muscles for stimulation may have lower motor neuron damage, rendering the muscles unexcitable. We have used surgical modification of the biomechanics of the hand to overcome this limitation. Tendon transfer of paralyzed but lower motor neuron intact muscles can compensate for potential function lost owing to muscles with lower motor neuron damage. Such procedures have been performed to provide finger extension, thumb extension, finger flexion, and wrist extension. Additional surgical procedures have been performed to enhance the function provided with electrical stimulation. These are side-to-side synchronization of the finger flexor and extensor tendons, the flexor digitorium superficialis Zancolli-lasso procedure, and thumb interphalangeal joint arthrodesis. These procedures have been performed in 11 patients with C5 and C6 level spinal injuries and functional electrical stimulation neuroprostheses. In these patients, 41 different functional electrical stimulation-related procedures were performed and 38 gave the desired result after surgery. One procedure resulted in no increase or decrease in function or muscle output, and two procedures resulted in a decrease in muscle force or joint range of motion. The issues that must be considered in performing functional electrical stimulation-related tendon transfers are discussed.

Electric Stimulation Therapy↗
PubMed1995

Downstaging by combination therapy with flutamide and an LHRH agonist before radical prostatectomy.

A total of 161 patients diagnosed as having stage B (134 patients) or C (27 patients) prostate cancer were randomly assigned to radical prostatectomy alone or to 3 months of neoadjuvant combination therapy with the anti-androgen flutamide and an LHRH agonist before radical prostatectomy. Neoadjuvant combination therapy before radical prostatectomy decreased cancer positive surgical margins from 33.8% in the control group to only 7.8%, thus leaving 92.2% of patients with negative margins at surgery for a 39.2% increase in specimen confined disease. Although on average the final stage determined at histopathological examination of the surgical specimen was more advanced than predicted at initial diagnosis in 33.8% of control patients, an opposite observation was made in the group of men who received the 3 month neoadjuvant combination therapy where the final stage, instead of being more advanced, was less advanced than at diagnosis in an average of 21.1% of men for a net 54.9% improvement of staging in favour of combination therapy. On the other hand, organ confined disease increased from 49.3% to 77.8% of patients after 3 months of combination therapy, for a 57.9% increase in the incidence of organ confined disease. Although long term follow up of these patients is required to determine the impact on survival, the marked influence of neoadjuvant combination therapy on the stage of the disease suggests the possibility of a major improvement in the morbidity and mortality from prostate cancer.

Aged↗
PubMed1994

Metastatic prostate cancer pulmonary nodules: beneficial effects of combination therapy and subsequent withdrawal of flutamide.

A case is presented of a middle-aged man suffering from stage D2 prostate cancer with pulmonary metastases who responded favorably, first, to endocrine combination therapy with the antiandrogen flutamide and an LHRH agonist for 5.5 years, and, second, to the subsequent withdrawal of Flutamide at the time of the progression of the disease. This case has several exceptional features: absence of bone metastases, pulmonary metastatic nodules characterized as focal neuroendocrine differentiation, and a positive response to antiandrogen withdrawal upon relapse of metastases after initial positive response. The concept of escape to androgen blockade and development of androgenic hypersensitivity is discussed.

Acid Phosphatase↗