William Pelon

Mutagenic activity of gastric juice

Gastric juice samples from patients of a rural area of the Colombian Andes at high risk to gastric cancer were tested for mutagenesis with Salmonella typhimurium strains TA100 and TA1538. Direct mutagenic effect was found in samples with detectable amounts of nitrite. This effect was not accountable by nitrite alone. Nitrite-negative samples from the same area and samples from the low-risk area of Cali were negative using the same mutagenesis assay.

Viral flora of the human alimentary tract

I N 1949, Enders and co-workers first described the successful propagat ion of poliovirus in in-vitro cultures of human embryonic cells. 1 Today, some 15 years later, the study of human viruses has expanded to the point where the virologist may expect to detect any one of 70 or more defined virus types from human feces a lone? q I t is difficult to estimate the number of addit ional agents isolated f rom human feces but not as yet characterized. Andrews judged this nmnber to be approximate ly 100. 5 Tab l e 1 presents data on those virus groups which contain serologicatly distinct virus types associated with infections of the human gastrointestinal tract. With the exception of one member of the E C H O virus group (ECHO Type 28), and a number of the adenovirus types, the tabulated agents were all uncovered after the inoculation of fecal specimens into appropr ia te host systems. T o date, E C H O Type 28 has been primari ly isolated from the respiratory tract, with only one isolation reported f rom fecesfi and is currently being considered as a member of the rhinovirus group. 7 Although a num ber of adenovirus types have been detected in specimens of feces, it is generally conceded that the pr imary sites of multiplication for these agents are in the nasopharyngeat area, and that such viruses often find their way into the intestinal tract as a result of release into the pharynx; s however, two members of this group have been associated with gastrointestinal disturbances2 T h e agent or agents of infections hepatitis still present a challenge for the virologist since suitable host systems for their isolation have not as yet been reported and confirmed. Much of the information currently available concerning the etiology of the disease and the nature of the agents involved has been collected from clinical studies and from studies in human volunteers. TM I t is of interest to note that the majori ty of the viruses isolated f rom feces are relatively small in size and are composed of ribonucleic acid. All

Hemagglutination by Reoviruses Propagated in Various Cell Lines.

Summary 1. Reovirus HA antigens prepared in the human diploid cell strain, WI-38 and in the established renal cell lines, LLC-MK2 and BS-C-1, may be satisfactorily employed in lieu of primary renal cell cultures of the Rhesus monkey. 2. Of the 3 host cell systems tested, WI-38 cells proved to be the most suitable for preparation of reovirus HA antigens. Maximum HA titers to the 3 reovirus types were obtained after 3 passages in this cell strain. 3. Higher reovirus HA titers were attained in stationary WI-38 cell cultures incubated at 37°C as compared with that obtained from cultures rotated at this temperature. The enhancement of CPE with respect to the methods of incubation varied with the virus strains employed. At an incubation temperature of 24°C only reovirus type 2 produced CPE and HA to a limited extent in WI-38 cells. 4. Reovirus types 1 and 2 HA antigens prepared in WI-38 cells showed no significant differences in titers when HA was carried out at temperatures of 4, 24 and 37°C. Antigens prepared with 3 strains of type 3 failed to agglutinate erythro-cytes at 4°C but demonstrated HA at 24 and 37°C.