Cytoprotective activity in the gastric mucosa of rats exposed to carbon tetrachloride-induced liver injury.

The present study was undertaken to evaluate the cytoprotective activity in the gastric mucosa of rats subjected to CCl4-induced liver injury. Response of gastric mucosa to absolute ethanol insult or acid (pylorus ligation) after CCl4 challenge was analyzed. Intraperitoneal administration of CCl4 increased plasma AST and ALT, but liver protein and glycogen levels were decreased; in addition, gastric acid secretion was significantly increased with respect to control animals (1541 +/- 266 vs. 629 +/- 25 mu eq H+; p < 0.001). Microscopical gastric erosions were observed in 3/10 animals after CCl4 challenge. Pylorus-ligated as well as CCl4-challenged rats developed increased susceptibility to gastric lesions, compared to control (lesion indices: 4.6 +/- 0.20 vs 2.8 +/- 0.13; p < 0.05), while showing increased resistance to absolute ethanol-induced gastric damage (30.4 +/- 11.2 vs 89.7 +/- 9.7 mm, p < 0.01). PGE2 levels in the gastric mucosa were not influenced by exposure to CCl4. Ultrastructural studies revealed the presence of continuous ethanol-resistant and apparently more adherent layer of mucus in CCl4-challenged animals. Morphological evaluation revealed an increase in Alcian blue-stained mucus. A dual condition of enhanced sensitivity to HCl with increased tolerance to ethanol was observed in gastric mucosa of CCl4-treated animals. These observations could be explained by the amount and/or composition of protective mucus layer in the gastric mucosa.

[Role of sun exposure on benign melanocytic nevi. A first study in populations controlled for age, sex and phenotype]. / Rôle de l'exposition solaire sur les naevus mélanocytaires bénins. Première étude dans des populations contrôlées pour l'âge, le sexe et le phénotype.

BACKGROUND: These studies were designed to assess the influence of sun exposure on nevi in white people. In order to eliminate the confounding effect of age, sex and phenotype, two parallel studies were conducted in people of the same age (17 to 24 years), sex (males) and phenotype: one in people with "red" phenotype and one in people with "dark" phenotype. RESULTS: In both groups, comparison of nevus counts on the inner and outer side of the upper extremities and comparison of mean density of nevi (number per square meter) in always-exposed and never-exposed skin show that number of nevi is higher in sun exposed areas. In both groups the density of large and atypical nevi was maximal on intermittently sun-exposed skin while the density of small nevi was maximal on always-exposed skin. The number of large nevi on intermittently-exposed skin correlated with cumulative intensive exposure during beach recreation in the red phenotype group. The number of large nevi was significantly higher in red phenotypes who repeatedly experienced severe sunburns in their first 20 years of life. CONCLUSIONS: The number of nevi at the end of the second decade is influenced by cumulative sun exposure from birth. "Traumatizing" sun exposure, which is more frequent in "red" phenotype than in "dark" one, has an influence on the number of large nevi and is therefore likely to make small nevi grow.

Role of sun exposure on nevus. First study in age-sex phenotype-controlled populations.

BACKGROUND: These studies were designed to assess the influence of sun exposure on nevi in white people. To eliminate the confounding effect of age, sex, and phenotype, two parallel studies were conducted on people of the same age (17 to 24 years; median, 20 years old), sex (male), and phenotype: one in people with "red" phenotype (red or red-blond hair, white complexion on the inner part of the arm, and inability to tan) and one in people with "dark" phenotype (brown or black hair, dark complexion on the inner part of the arm, absence of freckles, and easy tanning without burning). RESULTS: In both groups, comparison of nevus counts on the inner and outer side of the upper extremities and comparison of mean density of nevi (number per square meter) in always-exposed and never-exposed skin show that the number of nevi is higher in sun-exposed areas. The density of large and atypical nevi was maximal on intermittently sun-exposed skin while the density of small nevi was maximal on always-exposed skin. The number of large nevi on intermittently exposed skin correlated with cumulative intensive exposure during beach recreation in the red phenotype group. The number of large nevi was significantly higher in red phenotypes who repeatedly experienced severe sunburns in their first 20 years of life. CONCLUSIONS: The number of nevi at the end of the second decade is influenced by cumulative sun exposure from birth. "Traumatizing" sun exposure, which is more frequent in the red phenotype than in the dark phenotype, has an influence on the number of large nevi and is therefore likely to make small nevi grow.