Modified Genta triple stain for identifying Helicobacter pylori.
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AIM: To evaluate whether lead nitrate could replace uranyl nitrate in the Genta stain for H pylori without sacrificing the advantages of the triple stain (Steiner silver impregnation combined with Alcian blue and haematoxylin/eosin (H&E)). METHODS: A comparison was made in 16 specimens between the original triple stain and the revised version. One pathologist evaluated all sections. RESULTS: Direct substitution of lead nitrate for uranium nitrate produced well stained organisms without interfering with H&E or Alcian blue staining. No difference was found in the ability to identify bacteria in 11 cases with H pylori density of 1 or 2 (on a scale of 0 to 5). CONCLUSIONS: The potential chemical and radiological hazards associated with uranium nitrate can be eliminated by using lead nitrate without sacrificing the advantages obtained by using the triple stain. (+info)
Efficacies of imipenem, meropenem, cefepime, and ceftazidime in rats with experimental pneumonia due to a carbapenem-hydrolyzing beta-lactamase-producing strain of Enterobacter cloacae.
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The antibacterial activities of imipenem-cilastatin, meropenem-cilastatin, cefepime and ceftazidime against Enterobacter cloacae NOR-1, which produces the carbapenem-hydrolyzing beta-lactamase NmcA and a cephalosporinase, and against one of its in vitro-obtained ceftazidime-resistant mutant were compared by using an experimental model of pneumonia with immunocompetent rats. The MICs of the beta-lactams with an inoculum of 5 log(10) CFU/ml were as follows for E. cloacae NOR-1 and its ceftazidime-resistant mutant, respectively: imipenem, 16 and 128 microg/ml, meropenem, 4 and 32 microg/ml, cefepime, <0.03 and 1 microg/ml, and ceftazidime, 1 and 512 microg/ml. The chromosomally located cephalosporinase and carbapenem-hydrolyzing beta-lactamase NmcA were inducible by cefoxitin and meropenem in E. cloacae NOR-1, and both were stably overproduced in the ceftazidime-resistant mutant. Renal impairment was induced (uranyl nitrate, 1 mg/kg of body weight) in rats to simulate the human pharmacokinetic parameters for the beta-lactams studied. Animals were intratracheally inoculated with 8.5 log(10) CFU of E. cloacae, and therapy was initiated 3 h later. At that time, animal lungs showed bilateral pneumonia containing more than 6 log(10) CFU of E. cloacae per g of tissue. Despite the relative low MIC of meropenem for E. cloacae NOR-1, the carbapenem-treated rats had no decrease in bacterial counts in their lungs 60 h after therapy onset compared to the counts for the controls, regardless of whether E. cloacae NOR-1 or its ceftazidime-resistant mutant was inoculated. A significant decrease in bacterial titers was observed for the ceftazidime-treated rats infected with E. cloacae NOR-1 only. Cefepime was the only beta-lactam tested effective as treatment against infections due to E. cloacae NOR-1 or its ceftazidime-resistant mutant. (+info)
The entry of D-ribose into some yeasts of the genus Pichia.
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The utilization of D-ribose by yeasts of the genus Pichia was examined with respect to aerobic growth, respiration and entry of ribose into the cells. Pichia etchellsii (CBS2011) could respire D-ribose, but not use it for aerobic growth. Pichia fermentans (CBS187) neither respired nor grew on D-ribose, though it entered the cells of this yeast either by simple diffusion, or possibly, by the D-glucose carrier, this having a very low affinity for D-ribose. Pichia pinus (CBS5097) respired and grew on D-ribose; kinetic evidence is given for this yeast having two ribose carriers, one inducible and the other constitutive. (+info)
Effect of experimental renal failure on the pharmacokinetics of losartan in rats.
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The purpose of this investigation was to determine whether the pharmacokinetics of the angiotensin II receptor antagonist losartan is altered in renal failure. Male Wistar rats were pretreated with uranyl nitrate or subjected to bilateral ureteral ligation to produce acute renal failure (ARF). Saline-injected and sham-operated rats, respectively, served as controls. Uranyl nitrate-treated rats showed significantly higher serum concentrations of losartan after oral administration and the area under the serum concentration-time curve (AUC(0-24)) of losartan increased about 3-fold compared to control rats. The systemic clearance of losartan significantly decreased from 410 +/- 254ml/h/kg in control to 177 +/- 112ml/h/kg in uranyl nitrate-treated rats. In order to investigate the mechanisms of reduced clearance of losartan associated with ARF, a hepatic microsome fraction was prepared from normal and ARF rats. No significant difference was found in the metabolism of losartan by hepatic microsomes prepared from ARF and control rats. In addition, the metabolic activity of microsomes was examined in the presence of uremic rat serum. The unbound clearance of losartan and the unbound clearance associated with the formation of EXP3174 in the presence of uremic serum were significantly lower than those in the presence of control serum. Furthermore, the metabolism of losartan was inhibited by indoxyl sulfate, a uremic toxin, in an uncompetitive manner. These results suggest that ARF is associated with reduced clearance of losartan due to the inhibition of hepatic metabolism by accumulated uremic toxin(s). (+info)
Effects of acute renal failure on the pharmacokinetics of chlorzoxazone in rats.
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The purpose of this study is to report the changes of CYP2E1, CYP1A2, CYP2B1/2, CYP2C11, CYP3A23, and CYP3A2 expression and pharmacokinetics and tissue distribution of chlorzoxazone (CZX) and 6-hydroxychlorzoxazone (OH-CZX) in rats with acute renal failure induced by uranyl nitrate (U-ARF), and the role of CYP3A23 and CYP3A2 in the formation of OH-CZX in rats with U-ARF. In rats with U-ARF, CYP2C11 decreased to 20% of control, whereas CYP2E1 and CYP3A23 increased 2.3 and 4 times, respectively, compared with control. But expression of CYP1A2 and CYP2B1/2 was not changed by U-ARF. After i.v. administration of CZX at a dose of 20 mg/kg to rats with U-ARF, the areas under the plasma concentration-time curve from time 0 to time infinity (AUCs) of CZX and OH-CZX were significantly smaller and greater, respectively, than those in control rats. In rats with U-ARF, CZX was below the detection limit at 120 min in all rat tissues studied, whereas it was detected in all tissues of control rats at both 30 and 120 min. However, in control rats, OH-CZX was below the detection limit at both 30 and 120 min in all rat tissues except kidney, whereas it was detected in all tissues of rats with U-ARF at both 30 and 120 min. Based on results from supporting experiments with DDT and 2,2-bis(4-chlorophenyl)1,1-dichloroethylene treatment of rats, the contribution of CYP3A23 and CYP3A2 to the enhanced formation of OH-CZX in rats with U-ARF is likely to be negligible. (+info)
Differential effects of nephrotoxic agents on renal transport and metabolism by use of in vitro techniques.
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A number of studies by the author and other investigators are reviewed in which the in vitro kidney slice technique has been used to evaluate the nephrotoxicity of various compounds. The kidney slice technique can be used to determine the effect of prior drug treatment of laboratory animals on renal organic acid (p-aminohippurate) or organic base (N-methylnicotinamide) transport, on glucose synthesis, and on oxygen consumption by renal coritical slices. The nephrotoxic agents uranyl nitrate and potassium dichromate exert inhibitory effects on renal function, althouhg both agents enhance organic base transport at low doses and potassium dichromate enhances organic acid transport at moderate doses. Enhanced PAH transport has been found to be a sensitive indicator of gentamicin induced nephrotoxicity, while inhibition of other parameters has been reported. The tissue slice method is less effective in evaluation chronic nephrotoxicity such as that produced by lead. The inhibitory effect of mercurial diuretics has been shown to be due to the general depression of metabolic activity by mercury. The kidney slice technique has been found to be a sensitive indicator in the assessment of halogenated hydrocarbon-induced nephrotoxicity. Differential effects of compounds on in vitro organic acid and base trasport provides information about the transport of these compounds as well as about their nephrotoxicity. Although it is often desirable to perform in vivo tests or other in vitro renal function tests, the kidney slice technique has proved to be extremely useful in toxicological evaluations. (+info)
Role of alveolar macrophages in precipitation of mineral elements inhaled as soluble aerosols.
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The lysosomes of several varieties of cells such as the tubular proximal cell of the kidney and the alveolar macrophage have the ability to concentrate and precipitate several elements inhaled in water-soluble form, usually as phosphate. The mechanism involved is attributed to the high acid phosphatase activity of lysosomes and can be considered as an in vivo Gomori reaction. Among the elements studied, most of them are chemotoxic or radiotoxic (Cr; group IIIA: Al, Ga, In; rare earths: La, Ce, Tm; actinides: Th, U). In the lung macrophage, this mechanism of intralysosomal concentration and precipitation may prevent the diffusion of these toxic elements through the alveolar membrane. (+info)
Modification of pharmacokinetics of cefotaxime in uranyl nitrate-induced renal damage in black bengal goats.
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Pharmacokinetics of cefotaxime (50 mg/kg, i.m.) were studied in both healthy and kidney damaged female black Bengal goats. Uranyl nitrate (0.75 mg/kg) was administered intravenously, once daily for five consecutive days to induce kidney damage. The pharmacokinetic variables were calculated in both cases. Kidney damage caused several changes in the determined variables. The C(max) and C(min) of cefotaxime observed at 0.50 and 5 h in normal goats were 24.91+/-1.51 and 1.22+/-0.07 micro g/ml, respectively, while the same in kidney damaged goats at 1 and 72 h were 75.00+/-0.45 and 3.10+/-0.09 micro g/ml, respectively. Renal damage condition significantly increased t1/2,ka (0.48+/-0.01 h), t1/2,ke (20.03+/-0.16 h), AUC (2440.10+/-24.26 micro g. h/ml) and significantly decreased Vdarea (0.59+/-0.007 L/kg), Vss (0.58+/-0.007 L/kg) and ClB (0.02+/-0.008 L/kg/h) values of cefotaxime compared to normal goats. (+info)