Clinical, histologic and genetic characterization of non-Hodgkin's lymphomas in Mexicans.

We describe the anatomical distribution, histological and molecular characteristics of 32 cases of NHL. Staging of the NHL was made according to conventionally accepted schemes. Histologically the NHL were classified in grades following the criteria defined by the Working Formulation. Rearrangements in one or more Ig or TcR receptor genes were detected in Southern blots and allowed us to determine the cell type and stage of differentiation. Serological analysis of 26 serum samples revealed the existence of antibodies against EBV epitopes; eight of these patients carried viral sequences in the tumor genome as determined by slot blot hybridization. Our studies indicate that the use of various methods is of paramount importance in order to improve our understanding of the natural history of NHL.

[Causes and factors of diarrhea in the acquired immunodeficiency syndrome in a hospital of Mexico City]. / Causas y factores de diarrea en el síndrome de inmunodeficiencia adquirida en un hospital de la ciudad de México.

One hundred and sixty-four AIDS patients were studied; in 70 of them (42.7%) an agent capable of producing diarrhea was identified either by bacteriology, histopathology, or both procedures. It was observed that homosexuals and bisexuals present diarrhea sooner and with a higher frequency than heterosexuals. Cryptosporidium (35.7%) was the most frequently isolated agent. The most useful study was the coproparasitoscopic series. In 27 patients (38.6%) 2 or more agents (pathogens or opportunist) were isolated. An statistical correlation was demonstrated between the presence of diarrhea and the existence of agents able to produce it. The convenience of using special methods, because of their efficacy or cost, to evidence other pathogenic or opportunistic agents is also discussed.

Geographic variations in the histologic characteristics of the gastric mucosa.

Histologic sections of 205 gastrectomy specimens, which were obtained for benign and malignant diseases, were reviewed. All patients were Mexican nationals. The following histologic features were recorded: intestinal metaplasia, intramucosal cysts, ciliated gastric cells, and different types of pyloric cells ("ordinary"; with granular cytoplasm; with small cytoplasmic vacuoles; with large cytoplasmic vacuoles; or with homogeneous "glassy" cytoplasm). The percentage of specimens showing intestinal metaplasia was similar in those containing gastric ulcers (42.7%) or adenocarcinomas (50.0%). Intestinal metaplasia was decreased in men 59 years of age or older and in women 69 years of age or older. Diffuse-type adenocarcinoma accounted for 90% of the gastric tumors. Only 3 of the 205 specimens (1.9%) contained intramucosal cysts, and only 1 (0.4%) showed ciliated cells. Pyloric cells with granular cytoplasm were observed in 21.2% of the specimens, and pyloric cells with small cytoplasmic vacuoles were seen in 1.9%. Pyloric cells with large vacuoles or "glassy" cytoplasm were not found in any case. These results indicate differences in the proportions of several histopathologic findings in the gastric mucosa, between Mexicans and other ethnic groups that have been investigated in previous surveys. The authors' findings support the hypothesis that different environmental factors, acting in disparate geographic regions, may account for dissimilarities in the histologic appearance of "normal gastric mucosa."