Salmonella in Foods: New Enrichment Procedure for TECRA Salmonella Visual Immunoassay Using a Single RV(R10) Only, TT Only, or Dual RV(R10) and TT Selective Enrichment Broths (AOAC Official Method 998.09): Collaborative Study

A collaborative study was conducted to compare a new enrichment procedure for the TECRA® Salmonella Visual Immunoassay (TSVIA) with the reference method given in the U.S. Food and Drug Administration's Bacteriological Analytical Manual (7th Ed.). Three food types (milk powder, pepper, and soy flour) were analyzed in Australia and 3 food types (milk chocolate, dried egg, and raw turkey) were analyzed in the United States. Thirty-eight collaborators participated in the study. The TECRA method was evaluated using both Rappaport-Vassiliadis R10 (RV(R10)) and tetrathionate (TT) broths for selective enrichment. M broth cultures arising from each of the 2 selective enrichment broths were tested in the TSVIA using 2 individual wells, one for each selective broth, and a single well to test the pooled selective enrichment broths. The results for the pooled enrichment broths were reported elsewhere. This study presents the results for the use of single enrichment broths, i.e., RV(R10) only or TT only, with the TSVIA. No significant differences (p > 0.05) were observed for the pairwise comparison of the proportion of positive samples for either RV(R10) or TT used as a single enrichment broth for the TSVIA with that for the reference method.

Uranium-induced sensory alterations in the zebrafish Danio rerio

The effect of chronic exposure to uranium ions (UO(2)(2+)) on sensory tissues including the olfactory and lateral line systems was investigated in zebrafish (Danio rerio) using scanning electron microscopy. The aim of this study was to determine whether exposure to uranium damaged sensory tissues in fish. The fish were exposed to uranium at the concentration of 250 μg l(-1) for 10 days followed by a depuration period of 23 days. Measurements of uranium uptake in different fish organs: olfactory rosettes and bulbs, brain, skin, and muscles, were also determined by ICP-AES and ICP-MS during the entire experimental period. The results showed that uranium displayed a strong affinity for sensory structures in direct contact with the surrounding medium, such as the olfactory and lateral line systems distributed on the skin. A decreasing gradient of uranium concentration was found: olfactory rosettes>olfactory bulbs>skin>muscles>brain. At the end of the experiment, uranium was present in non-negligible quantities in sensory tissues. In parallel, fish exposed to uranium showed severe sensory tissue alterations at the level of the olfactory and lateral line systems. In both sensory systems, the gross morphology was altered and the sensory hair cells were significantly damaged very early after the initiation of exposure (from the 3rd day). At the end of the experiment, after 23 days of depuration, the lateral line system still displayed slight tissue alterations, but approximately 80% of the neuromasts in this system had regenerated. In contrast, the olfactory system took more time to recover, as more than half of the olfactory rosettes observed remained destroyed at the end of the experiment. This study showed, for the first time, that uranium is able to damage fish sensory tissues to such an extent that tissue regeneration is delayed.

Overexpression of cytosolic glutathione peroxidase (GPX1) delays endothelial cell growth and increases resistance to toxic challenges

Oxidative stress results from the imbalance between reactive oxygen species (ROS) and ROS-scavenging molecules. Among them, cytosolic glutathione peroxidase (GPX1) plays a major role as it reduces a large part of intracellular ROS. Endothelial cells are a barrier for potentially aggressive molecules circulating in the blood stream and, therefore, are often under great oxidative stress. Thus, we investigated the potentially protective effects of GPX1 overexpression in the endothelial cell line, ECV304. We found that chronic GPX1 overexpression delays cell growth without affecting viability or decreasing resistance to hydrogen peroxide-induced oxidative stress. As GPX1 overexpression could drain the cellular reduced glutathione (GSH) pool, we also tested the effects of extracellular GSH supplementation on cell growth. Despite its largely referenced beneficial effects for cells, GSH was toxic for ECV304 cells in a dose-dependent manner but GSH-induced toxicity was reduced in selenium supplemented cultures and completely abolished in ECV304 overexpressing GPX1, compared to control. In summary, GPX1 overexpression delays cell growth and protects them from GSH and H(2)O(2) toxicity.

Gemcitabine in leukemia: a phase I clinical, plasma, and cellular pharmacology study

PURPOSE

Phase I clinical and in vitro studies of gemcitabine (2',2'-difluorodeoxycytidine; dFdC) have demonstrated that the accumulation rate of dFdC 5'-triphosphate (dFdCTP) in mononuclear and leukemia cells is saturated when plasma or extracellular dFdC levels exceed 15 to 20 mumol/L. Thus, we designed a phase I study to maximize the accumulation of dFdCTP by leukemia cells by administering dFdC at 10 mg/m2/min, a dose rate calculated to produce steady-state plasma dFdC levels that exceed 15 to 20 mumol/L.

PATIENTS AND METHODS

The treatment intensity was increased in patients (n = 22) with relapsed or refractory acute leukemia or chronic myelogenous leukemia (CML) in blast crisis by prolonging the infusion duration but maintaining the same rate. Doses of dFdC between 1,200 mg/m2 and 6,400 mg/m2 were administered weekly for 3 weeks.

RESULTS

The maximum-tolerated dose was 4,800 mg/m2 infused over 480 minutes. The mean steady-state dFdC level in plasma of all infusions was 26.5 +/- 9 mumol/L (n = 19). The accumulation rates of dFdCTP in circulating leukemia cells varied greatly among patients but remained linear in eight patients infused for 120 to 240 minutes, and up to or beyond 360 minutes in five of eight additional patients. Elimination of dFdCTP was significantly related to its cellular concentration: blasts with greater than 450 mumol/L dFdCTP exhibited biphasic elimination, whereas blasts with lower dFdCTP concentrations exhibited linear kinetics. Biphasic elimination was associated with higher dFdCTP areas under the concentration-times-time curve (AUCs) and greater inhibition of DNA synthesis.

CONCLUSION

Studies of the cellular pharmacology and pharmacodynamics of dFdC may be useful in optimizing protocol designs for leukemia.