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Biomedical subjects

M Gosselin

Publications and source records attributed to M Gosselin.

125 records · Page 7Linked to original sources
PubMedDate not supplied

Simulation of ozone depletion using ambient irradiance supplemented with UV lamps.

In studies of the biological effects of UV radiation, ozone depletion can be mimicked by performing the study under ambient conditions and adding radiation with UV-B lamps. We evaluated this methodology at three different locations along a latitudinal gradient: Rimouski (Canada), Ubatuba (Brazil) and Ushuaia (Argentina). Experiments of the effect of potential ozone depletion on marine ecosystems were carried out in large outdoor enclosures (mesocosms). In all locations we simulated irradiances corresponding to 60% ozone depletion, which may produce a 130-1900% increase in 305 nm irradiance at noon, depending on site and season. Supplementation with a fixed percentage of ambient irradiance provides a better simulation of irradiance increase due to ozone depletion than supplementation with a fixed irradiance value, particularly near sunrise and sunset or under cloudy skies. Calculations performed for Ushuaia showed that, on very cloudy days, supplementation by the square-wave method may produce unrealistic irradiances. Differences between the spectra of the calculated supplementing irradiance and the lamp for a given site and date will be a function of the time of day and may become more or less pronounced according to the biological weighting function of the effect under study.

Canada↗
PubMedDate not supplied

Quantitation of chemokines (MDC, TARC) expression in mucosa from Crohn's disease and ulcerative colitis.

Chemokines and their receptors are involved in the migration of different mononuclear cells. Among them macrophages-derived chemokines (MDC) and thymus-and activation regulated chemokine (TARC) belong to a new cluster of genes involve in Th2 lymphocytes homing. Cytokines appear to play a significant role in pathogenesis of inflammatory bowel diseases with an excessive Th1 response in chronic lesions of Crohn's disease (CD) and a Th2 pattern in both earlier mucosal CD lesions and in mucosa of ulcerative colitis (UC). Here we demonstrate that RNAm coding for MDC and TARC are expressed in mucosa from CD and UC patients. Using real-time fluorescent RT-PCR, MDC and TARC mRNA were increased in CD inflamed mucosa. Moreover MDC and TARC transcripts were increased in inflamed CD specimen compared to non-involved CD mucosa. These differences both discriminate CD from UC patients. Additionally, MDC protein was produced in isolated mononuclear cells from peripheral blood (PBMC) or mucosa (LPMC) from UC and CD patients: spontaneously, MDC production from PBMC was increased in CD compared to UC patients. MDC production from CD PBMC was also higher than that found in healthy controls. Together, these data indicate that MDC should be involved in the lymphocytes homing in mucosa from CD patients.

Adolescent↗
PubMedDate not supplied

[Gastroduodenal ulcer and psychology].

Ulcers do not necessarily and uniquely constitute a psychogenic disease. Life events may play a role in certain subjects but their occurrence is neither necessary (absence in numerous ulcerous patients) nor sufficient (presence in controls) for triggering ulcerous development. While the actual experiences involved are important, there is no personality type linked to development of ulcers. Some specialists call attention to a tendency to react to conflicts according to a particular pattern (dependence-independence, passivity-hyperactivity); others refer to various modes of personality breakdown ot to the accentuation of certain personality traits. At the present time there is no satisfactory explanation of the mechanism governing the links between psychological disturbances and gastroduodenal anatomical lesions. The role of psychotherapy in the treatment of ulcers is poorly understood.

Duodenal Ulcer↗
PubMedDate not supplied

[Manometric effects of metopimazine on the lower esophageal sphincter (author's transl)].

The effects of metopimazine on gastric, jejunal and colonic motility were recently described. The purpose of this study is to evaluate the action of a bolus injection of metopimazine (10 mg IV) on lower esophageal sphincter pressure with continuously perfused catheters. Significative increase (p less than 0,05) of lower esophageal sphincter pressure is always observed in 10 normal subjects and 5 patients with symptomatic gastro-esophageal reflux. The rate of lower esophageal sphincter pressure increase is significantly (p less than 0,05) more important in the symptomatic patients (160 +/- 19) than in controls (134 +/- 20). Further clinical study will be required to confirm these first data before proposing metopimazine as treatment of lower esophageal sphincter incompetence with gastro-oesophageal reflux.

Adult↗
PubMedDate not supplied

Caroli's disease: a surgical dilemma.

We report the case of a 31-year-old male patient with a diffuse form of Caroli's disease presenting as recurring bouts of biliary pancreatitis. Following sphincterotomy, the patient remained asymptomatic for 5 years. He then developed acute cholangitis and, at laparotomy, all superficial liver cysts were fenestrated in order to remove intrahepatic bile duct calculi. A right hepatectomy, removing the most severely affected liver parenchyma was not considered feasible because of the small size of the left lobe and the existence of an associated congenital hepatic fibrosis. In diffuse forms of Caroli's disease biliary drainage techniques have often proved ineffective in preventing recurring bouts of cholangitis. Moreover, liver resection is seldom feasible because of associated congenital hepatic fibrosis. In this setting, liver transplantation may represent the only effective and durable form of treatment.

Adult↗