Comparative Efficiency of Brilliant Green, Bismuth Sulfite, Salmonella-Shigella, Hektoen Enteric, and Xylose Lysine Desoxycholate Agars for the Recovery of Salmonella from Foods: Collaborative Study

The relative efficiency of brilliant green (BG), bismuth sulfite (BS), Salmonella-Shigella (SS), xylose lysine desoxycholate (XLD), and Hektoen enteric (HE) agars for the recovery of Salmonella from 5 foods was collaboratively studied in 11 laboratories. The analytical efficiency of various paired combinations of the 5 agars was statistically compared according to 3 parameters: (1) productivity or recovery of Salmonella, (2) rate of enumeration of cultures that were false positive for Salmonella, and (3) rate of enumeration of false-negative reactions. In descending order of productivity, the sequential rankingwasBS, XLD, HE, BG, and SS agars. In ascending order, the rates of false-positive reactions based on a statistical analysis of paired agar combinations was HE, BS, BG and XLD (tie), and SS agars. Analogously, in ascending order, the sequence of false-negative reaction rates was BS, XLD, HE, BG, and SS agars. The combination of BS, XLD, and HE agars is more efficient for recovery of Salmonella from foods than is the present official combination of BG, BS, and SS agars. The revision of official final action method 46.054 to replace the combination of BG, BS, and SS agars with a combination of BS, XLD, and HE agars has been adopted official first action.

Integrity of perfused rat liver at different heat loads

Isolated rat livers were perfused for 90 minutes at temperatures from 37 degrees to 43 degrees C. to evaluate the effects of heat alone on bile production, alanine aminotransferase, and asparate aminotransferase release, and light and electron microscopic structure. Bile production reached a plateau after 45 minutes at 43 degrees C. and after 60 minutes at 42 degrees C. At temperatures between 39 degrees and 41 degrees C., bile production was not significantly different from that produced at 37 degrees C. The timing and levels of alanine aminotransferase and aspartate aminotransferase released into the perfusates were similar, with increases after 45 minutes at 43 degrees C., after 60 minutes at 41 degrees and 42 degrees C. and after 75 minutes at 39 degrees and 40 degrees C. At the end of the 90-minute perfusion, light microscopy indicated vacuolization and severe dissociation of hepatocytes at 42 degrees and 43 degrees C., and pronounced centrilobular vacuolization at 41 degrees C. Electron microscopy demonstrated that hepatocytes had sustained extensive damage at 41 degrees to 43 degrees C. Mild focal and probably reversible damage occurred at 39 degrees and 40 degrees C. Since pH and O2 levels were regulated in a nonrecirculating system and perfusion rates were constant, neither acidosis, hypoxia, nor circulatory inadequacy were responsible for the alterations. Therefore, changes were attributed to the direct effects of heat, reflected a continuum from no detectable damage at 37 degrees C. to occasional necrosis of individual cells at 39 degrees to 40 degrees C. and culminated in widespread necrosis at 41 degrees to 43 degrees C. with a 90-minute exposure. These results reflect a time/temperature relationship over a range of temperatures. A hypothesis for the sequence of events in the pathogenesis of heat-induced hepatic injury is described.

Use of chromatography tubes in triiodothyronine and thyroxine RIA

Simple, convenient radioimmunoassays for total triiodothyronine and total thyroxine in human serum are discribed. Ascending dry column chromatography is used to separate the free and antibody-bound hormone. The method allows for separation by absorption, without centrifugation. The use of test tubes containing pre-measured quantities of lyophilized radioactive reagent obviates unnecessary handling of radioactive solutions.

Chromatography tubes: a novel RIA technique

We describe a novel radioimmunoassay in which separation of free and antibody-bound antigen is achieved by passive means. The separation is carried out by a modified form of inverted dry column chromatography on a column, or 'chromatography tube', consisting of a small polystyrene tube packed with a dry, insoluble, hydrophilic resin. Using the radioimmunoassay or digoxin as an example, an exceptionally simple procedure is described with sensitivity, accuracy and precision suitable for clinical purposes. Advantages of the chromatography tube method are discussed.

Detection of Salmonella in onion and garlic powders: collaborative study

The relative efficiency of trypticase soy broth with added 0.5% K2SO3 and lactose broth as pre-enrichment media for recovering Salmonella from onion powder and garlic powder was collaboratively studied. For each spice, 13 collaborators each received 5 duplicate samples; 4 of the 5 replicate samples were inoculated with 1 of 4 levels of S. thompson ranging, at initiation of analysis, from greater than 3 to 93 organisms/g onion powder and greater than 3 to 43 organisms/g garlic powder. Salmonella growth was inhibited in each of these spices as evidenced by a rapid decline of most probable number values in samples determined immediately after and 7 days following inoculation. Collaborative results of cultural analyses demonstrated superiority of the modified tripticase soy broth for recovering Salmonella in each of the 2 spices. The improved method of detecting Salmonella in onion and garlic powders has been adopted as official first action.

[Efficiency of cancer-preventive examinations. Problems in early detection for the physician and laboratory]

The efficiency of gynecological cancer detection and verification depends on optimal team work of different medical specialties, such as General Medicine, Gynecology, Cytopathology, Histopathology, Surgery, Radiology. Each number of the team, working incompetently in its field, lowers the efficiency of the whole group. The most important factors leading to inefficiency in gynecological cancer detection and verification are discussed. The comparison of two different sized cancer detection programs (1962-1964; 38 119 patients vs. 1968--1976: 331 355 patients) revealed that the efficiency of verification of cancer cases does not improve with the size of the program: The cancer verification rates were higher in the small program with less routine work-up material (verification rate: 80%) compared withe the big program containing mostly follow-up cases (verification rate:75%). Much more attention should be paid to the control of optimal cooperation of the medical specialties participating in a cancer detection program, since not only the size of a program but the quality of the work-up can improve the results in cancer detection.

Rheologic properties of erythrocytes in Duchenne muscular dystrophy

The transformation of erythrocytes into echinocytes by suspension in isotonic phosphate buffer was increased in patients with Duchenne muscular dystrophy (DMD) as compared to healthy controls. The transformation was enhanced when glass slides instead of polystyrole slides were used for observation. Viscosity of erythrocyte suspensions with a hematocrit of 80% was the same in patients and controls. The mean flow rate of erythrocyte suspensions in autologous plasma was only slightly reduced in the patient group, but decreased markedly after suspension of the cells in phosphate buffer, without as well as after preincubation with 10 mM Na salicylate. The decreased flow rate in patients is probably due to the increased number of echinocytes and not to an increased membrane rigidity, because the membrane flexibility of isolated ghosts, measured in a viscosimeter, was normal at all shear rates. Echinocyte formation in patients with DMD is strongly dependent on the techniques applied and difficult to evaluate quantitatively by phase contrast microscopy. Filtration of erythrocyte suspensions seems to be a more reliable, quantitative test for increased erythrocyte vulnerability.