Increasing frequency of gastric lymphoma in two national institutes of health in Mexico.

BACKGROUND: Some studies performed in developed countries with caucasian population have suggested an increase in the frequency of primary gastric lymphoma (PGL) in the past two decades. OBJECTIVE: To establish the frequency of PGL in two National Institutes of Health in Mexico in an interval of 18 years. METHODS: We reviewed 1,854 gastric malignant neoplasms diagnosed between 1979-1996 in mestizo patients seen at two different institutions. One of them (INC) is an oncological hospital, whereas the other one (INN) is a general hospital which treats patients with benign as well as malignant gastrointestinal diseases. RESULTS: A hundred and sixty three (8.8%) gastric lymphomas were identified from 1,854 gastric malignant tumors. The incidence of PGL showed a two to three-fold increase in the last years of the study in both institutions. The increased frequency was highly significant when compared to the initial rate. This increase does not appear to be due to patient selection criteria nor to the number of malignant gastric tumors in our institutions. CONCLUSIONS: Our results indicate an increased frequency of PGL the patient population of two National Institutes of Health in Mexico during the last years. Additional studies are necessary in order to define in the increase in PGL is limited to certain geographical areas or ethnic groups.

Steroids modulate the excitability of crayfish (Procambarus digueti) photoreceptors: long- and short-term actions.

Short- and long-term actions of the steroids corticosterone, progesterone, and ecdysterone were analyzed upon excitability of crayfish retinular cells. The three hormones showed short-term actions, particularly during photoreceptor dark adaptation; effects were found to be dependent on the hour of the day. Corticosterone and progesterone had similar effects, i.e., resembled dark-adapted conditions; ecdysterone actions were opposite and resembled light adaptation. Long-term effects were opposed to short-term effects in all cases. Possible mechanisms underlying these effects are discussed.