Symptoms associated with diarrhoeal illness at San Lazaro Hospital, Manila in 1983 and 1984.

The clinical features associated with various agents of diarrhoeal disease were studied using 2,836 patients admitted to San Lazaro Hospital, Manila. Three general patient groups were considered including single pathogen isolations, "multiple pathogen" isolations, and "no pathogen" isolations. In general, symptoms of diarrhoeal illness were found to be non-specific. However, Shigella flexneri. Vibrio parahemolyticus, and rotavirus were significantly associated with a number of prominent symptoms and could sometimes be predictably diagnosed on clinical grounds, especially when age of the patient was considered. Clinical diagnosis cannot be considered an adequate substitute for laboratory methods; other enteric pathogens can sometimes present with the same symptoms. When appropriate laboratory testing is unavailable, as is often the case in developing countries, symptomatologic diagnosis may be of limited value for the organisms mentioned.

Two-year survey of etiologic agents of diarrheal disease at San Lazaro Hospital, Manila, Republic of the Philippines.

The prevalence of bacterial pathogens and rotavirus in 2,908 patients with diarrhea who were admitted to San Lazaro Hospital in Manila in 1983 and 1984 was determined. One or more enteric pathogens were isolated or detected in samples from 1,698 (58.4%) patients. Isolation rates for the various enteropathogens were as follows: rotavirus, 30.6%; Shigella spp., 11.6%; Salmonella spp., 9.2%; enterotoxigenic Escherichia coli (1983 only), 7.8%; Vibrio cholerae biotype eltor, 3.8%; non-O1 V. cholerae, 2.8%; Vibrio parahaemolyticus, 1.7%; other Vibrio spp., 1.1%; Campylobacter jejuni, 3.0%; Aeromonas hydrophila, 1.3%; and Plesiomonas shigelloides 1.1%. Giardia lamblia and Entamoeba histolytica were detected in 0.6 and 0.1%, respectively, of stool samples examined. Determination of the etiologic role of isolates was complicated by one or more of the following factors: isolation of multiple enteric pathogens (302 cases); isolation of Salmonella spp., enterotoxigenic E. coli, and C. jejuni from a similar proportion of asymptomatic control patients and patients with diarrhea; and isolation of a high proportion of certain pathogens (especially Salmonella spp.) only from enrichment broth, suggesting infection with a small number of organisms. Isolation of V. cholerae eltor was seasonal, with the majority of cases occurring in the rainy months. In addition, the number of patients with diarrhea increased with the onset of the monsoon rains and peaked during the months of maximum rainfall. Rotavirus infection occurred in both children and adults throughout the year and was the most frequently identified cause of diarrhea in children under 5 years of age. Shigella spp. were the most common agents of diarrhea in adults.

Increased recovery of enteric pathogens by use of both stool and rectal swab specimens.

During 1984, the recovery of enteric pathogens from patients with acute diarrhea was enhanced by the use of both rectal swab and stool specimens. With 513 patients for whom both methods were used, the overall recovery rate was increased a minimum of about 10%. Almost 50% of the organisms recovered were detected by only one method. For maximum recovery of diarrheal agents, the use of both methods is recommended when possible.

Glycerol, sucrose, and other diol-containing reagents are not inert components in in vitro incubations containing aminoacyl-tRNA.

The addition of glycerol, sucrose, or other diol-containing reagents to solutions of aminoacyl-tRNA (aa-tRNA) substantially increased the rate of hydrolysis of the aminoacyl ester bond. Glycerol at 4.9% (v/v) doubled the rate of deacylation for several aa-tRNAs and peptidyl-tRNAs, including fMet-tRNAMetf, while 1% (v/v) glycerol increased the deacylation rate by 20%. This effect was not caused by a nuclease contamination, and tRNA deacylated in the presence of glycerol could be fully recharged. The deacylation of aa-tRNA was accelerated by glycerol and sucrose even in the presence of EF-Tu X GTP. In addition, the extent of tRNA aminoacylation was reduced when glycerol was present at concentrations above 2% (v/v). Thus, glycerol and sucrose are not necessarily inert or neutral additions to an in vitro incubation.

Changes in aminoacyl transfer ribonucleic acid conformation upon association with elongation factor Tu-guanosine 5'-triphosphate. fluorescence studies of ternary complex conformation and topology.

The association of aminoacyl-tRNA (aa-tRNA) with elongation factor Tu.GTP to form an aa-tRNA.EF-Tu.GTP ternary complex was investigated by using two different fluorescent probes, both of which monitored structural changes near the juncture of the two arms of the L-shaped tRNA. Aminoacylation of tRNAPhe-F8, a functionally active analogue of tRNAPhe with a fluorescein moiety covalently attached to the s4U-8 base, did not cause a change in the fluorescence emission intensity. However, when EF-Tu.GTP bound to Phe-tRNAPhe-F8, the emission intensity increased by approximately 30%, depending upon the solvent conditions. About half of this increase in fluorescence was due to an increase in the molar absorptivity of the fluorescein dye. Ternary complex formation did not alter the rate of iodide ion quenching of the Phe-tRNAPhe-F8 fluorescence. Since solvent access to fluorescein was not reduced when EF-Tu.GTP was bound to Phe-tRNAPhe-F8, the fluorescence intensity change noted above was not caused by a direct interaction between fluorescein and EF-Tu. Instead, the binding of EF-Tu.GTP to the aa-tRNA resulted in a conformational change in the aa-tRNA near s4U-8. Ternary complex formation also altered the nature of the single strong binding site for ethidium in unfractionated and unmodified aa-tRNA. However, ethidium binding to its strong site was not blocked. These results indicate that only the acceptor-T psi C arm of aa-tRNA interacts directly with EF-Tu.GTP and that the anticodon-D arm is available for direct interaction with the ribosome during recognition. Our data also suggest that EF-Tu facilitates protein biosynthesis by ensuring that every aa-tRNA is in a particular (possibly the same) conformation prior to initiation of the recognition process at the ribosomal complex.