Upgraded Cobas Ampliprep-Cobas TaqMan version 2.0 HIV-1 RNA quantification assay versus first version: correction of underestimations.

The large underestimations of HIV RNA quantification observed in 17 patients with the first version of Cobas TaqMan assay have been successfully corrected in the upgraded version 2.0. In comparison with the Abbott RealTime assay, the mean difference that was 1.18 log(10) copies/ml is now zero. The discrepancies have disappeared.

Spectral unmixing applied to fast identification of γ-emitting radionuclides using NaI(Tl) detectors.

Spectral unmixing was investigated for fast spectroscopic identification in γ-emitter mixtures at low-statistics in the case of measurements performed to prevent illegal nuclear material trafficking or for in situ environmental analysis following a radiological or nuclear accident. For that purpose, a multiplicative update algorithm based on full-spectrum analysis was tested in the case of a 3″x3″ NaI(Tl) detector. Automatic decision-making was addressed using Monte Carlo calculations of decision thresholds and detection limits. The first results obtained with a portable instrument equipped with a 3″x3″ NaI(Tl) detector designed for the control of food samples by non-expert users following a radiological or nuclear accident, are also presented.

Modulated expression of cell surface molecules and in vivo outgrowth of modified melanoma cells.

Modulation of cell surface molecules involved in immune recognition and cellular interactions (class I major histocompatibility complex or MHC-I, B7.1 or CD80, integrin alpha4 or CD49d, tetraspanins CD9, CD81) was examined in modified B16 melanoma cells displaying either inhibited IGF-I expression or transfected OVA encoding gene. It was shown that inhibiting IGF-I expression or inserting OVA encoding gene did not lead to modification relevant to the presence of MHC-I or B7.1. However downregulation of tetraspanin CD9 was observed in modified IGF-I but not in OVA encoding gene inserted melanoma cells. Expression of tetraspanin CD81 and integrin alpha4/CD49d remained unchanged. Inoculated into syngeneic recipients, the modified melanoma cells exhibited significant delayed outgrowth with a reduction in the percentage of lethal tumors observed essentially in hosts injected with inhibited IGF-I expression cells.

Real-time radionuclide identification in γ-emitter mixtures based on spiking neural network.

Portal radiation monitors dedicated to the prevention of illegal traffic of nuclear materials at international borders need to deliver as fast as possible a radionuclide identification of a potential radiological threat. Spectrometry techniques applied to identify the radionuclides contributing to γ-emitter mixtures are usually performed using off-line spectrum analysis. As an alternative to these usual methods, a real-time processing based on an artificial neural network and Bayes' rule is proposed for fast radionuclide identification. The validation of this real-time approach was carried out using γ-emitter spectra ((241)Am, (133)Ba, (207)Bi, (60)Co, (137)Cs) obtained with a high-efficiency well-type NaI(Tl). The first tests showed that the proposed algorithm enables a fast identification of each γ-emitting radionuclide using the information given by the whole spectrum. Based on an iterative process, the on-line analysis only needs low-statistics spectra without energy calibration to identify the nature of a radiological threat.

Peripheral antioxidant enzyme activities and selenium in elderly subjects and in dementia of Alzheimer's type--place of the extracellular glutathione peroxidase.

Defenses against free radical damage were determined in red blood cells and plasma from 40 patients with dementia of the Alzheimer-type (DAT) and 34 aged control subjects with normal cognitive function. No crude significant difference in erythrocyte copper-zinc superoxide dismutase (E-CuZnSOD), seleno-dependent glutathione peroxidase (E-GSH-Px), glutathione reductase (E-GSSG-RD) activities, and selenium (Se) concentration was found between DAT cases and control subjects. The peroxidation products evaluated in plasma by the thiobarbituric-reactive material (TBARS) were at the same level in the DAT group as compared to controls. In the DAT group, plasma GSH-Px (P-GSH-Px) activity and plasma Se (P-Se) were negatively correlated with age (r = -0.58; p < 0.001 and r = -0.63; p < 0.001 respectively). Moreover, erythrocyte GSH-Px activity and Se were also negatively correlated with age (r = -0.40; p < 0.01 and r = -0.46; p < 0.01, respectively). No significant correlation with age was observed in the controls. When controlling for age, a significant increase for P-GSH-Px activity and P-Se was observed in DAT patients as compared to controls. These significant differences mostly appeared in DAT subjects under 80 years. Some correlations were only observed in the DAT group such as P-GSH-Px and E-GSH-Px (r = +0.68; p < 0.001); P-GSH-Px and E-Se (r = +0.79; p < 0.001). Correlations between P-GSH-Px and P-Se, E-GSH-Px and P-Se, and P-Se with E-Se are greater in the DAT group (r = +0.84; p < 0.001; r = +0.76; p < 0.001 and r = 0.75; p < 0.001) than in the control group (r = 0.54, pI < 0.01; r = 0.43, p < 0.01 and r = +0.34, p < 0.05 respectively). The fact that first -- a significant increase in P-GSH-Px and P-Se, second -- some modifications in the relationships between antioxidant parameters, and third -- age-dependent decreases of glutathione-peroxidase activities and their cofactor, appeared only in the DAT group suggest that DAT is associated with an oxidative stress due to an imbalance between reactive oxygen species and the peripheral antioxidant opposing forces.

Glutathione antioxidant system as a marker of oxidative stress in chronic renal failure.

A profound imbalance between oxidants and antioxidants has been suggested in uremic patients on maintenance hemodialysis. However, the respective influence of uremia and dialysis procedure has not been evaluated. Circulating levels of copper-zinc superoxide dismutase (CuZn SOD), glutathione peroxidase (GSH-Px), and reductase (GSSG-Rd), total GSH and GSSG were determined in a large cohort of 233 uremic patients including 185 undialyzed patients with mild to severe chronic renal failure, and 48 patients treated by peritoneal dialysis or hemodialysis. Compared to controls, erythrocyte GSH-Px and GSSG-Rd activities were significantly increased at the mild stage of chronic uremia (p < .001), whereas erythrocyte CuZn SOD activity was unchanged, total level of GSH and plasma GSH-Px activity were significantly decreased, and GSSG level and GSSG-Rd activity were unchanged. Positive Spearman rank correlations were observed between creatinine clearance and plasma levels of GSH-Px (r = .65, p < .001), selenium (r = .47, p < .001), and GSH (r = .41, p < .001). Alterations in antioxidant systems gradually increased with the degree of renal failure, further rose in patients on peritoneal dialysis and culminated in hemodialysis patients in whom an almost complete abolishment of GSH-Px activity was observed. In conclusion, such disturbances in antioxidant systems that occur from the early stage of chronic uremia and are exacerbated by dialysis provide additional evidence for a resulting oxidative stress that could contribute to the development of accelerated atherosclerosis and other long-term complications in uremic patients.

Selenium and oxygen-metabolizing enzymes in elderly community residents: a pilot epidemiological study.

OBJECTIVE: To investigate the relationship of selenium and oxygen-deactivating enzymes with age in the elderly. SAMPLE: The study sample consisted of volunteers recruited from the PAQUID study. This study is conducted in a representative sample of non-institutionalized individuals aged > or = 65 years living in Southwestern France; its main objective is to study longitudinally the incidence and risk factors of dementia. METHODS: Plasma and erythrocyte selenium and activities of oxygen metabolizing enzymes in erythrocytes (GSH-Px, CuZn-SOD, and GSSG-RD) were measured in 239 volunteers (108 males and 131 females; mean age 73.7 years). RESULTS: Plasma selenium (PSe) decreased significantly with age; a similar but non-significant trend was found for erythrocyte selenium (ESe). None of the enzyme activities showed a clear relationship with age. Women had significantly higher GSH-Px activities than men. For PSe levels lower than 77 ng/mL, there was a strong correlation between PSe and GSH-Px; above this value, the correlation decreased, suggesting that the selenium requirement for GSH-Px production had been satisfied. In this sample, CuZn-SOD was correlated negatively with GSH-Px (r = -0.18; P < or = 0.01) and positively with GSSG-RD (r = +0.20; P < or = 0.01). CONCLUSIONS: In individuals aged > or = 65 years, we found that blood selenium levels were negatively correlated with age. Our analysis of the relationship between selenium and GSH-Px activity suggests that low selenium values are associated with decreased GSH-Px activity.

Effect of ethanol and ether in the prevention of calcification of bioprostheses.

BACKGROUND: Lipids play a significant role in the process of calcification of bioprostheses. We assessed whether lipid extraction by ethanol, ether, or a surfactant could mitigate calcification of glutaraldehyde-treated bioprostheses. METHODS: On 200 bovine pericardium samples pretreated with 0.6% glutaraldehyde, lipid extraction was carried out by ethanol, ether, or the tween 80 surfactant, and combinations thereof. The treated tissues were implanted subcutaneously in 50 juvenile rats for 4 and 6 months. Lipids were analyzed by Fourier transform infrared spectrophotometer and chromatography before implantation. Calcium content of implanted tissues was assessed by atomic absorption spectrometer. RESULTS: Ethanol, ether, or surfactant did mitigate calcification. The most efficient pretreatments were the combination of ethanol and surfactant (calcium content: 15.5+/-6.8 microg/mg dry tissue after 6 months implantation) or the combination of ethanol, ether, and surfactant (13.1+/-6.2 microg/mg dry tissue) when compared with surfactant alone (42.9+/-12.7 microg/mg dry tissue). CONCLUSIONS: Ethanol or the combination of ethanol and ether added to the currently used glutaraldehyde-surfactant treatment further mitigates calcification.

[Smoking and serum alpha 1-antitrypsin in 1296 healthy men (author's transl)]. / alpha 1-Antitrypsine et tabac, une étude de 1296 hommes sains.

Serum alpha 1-antitrypsin (alpha 1AT) was measured by radial immunodiffusion in 1296 healthy men aged 18--50 years. Other biological criteria, including leukocyte count and alpha 2-globulins were measured and the subjects were given a detailed questionnaire on their smoking habits. Results showed a very strong positive relationship between smoking and serum alpha 1AT: the heavy smokers had a serum alpha 1AT 20% higher than the non-smokers, and among subjects who stopped smoking, the level returned rapidly to normal. There were also close interrelationships between serum alpha 1AT, smoking, leukocyte count and a alpha 2-globulins. A discussion of these results is presented.

Effect of age and photoperiodic conditions on metabolism and oxidative stress related markers at different circadian stages in rat liver and kidney.

It has been shown that some cytochrome P450-dependent enzyme activities could present daily fluctuations, particularly CYP3A isoenzymes which are enhanced during the dark period. The aim of this study was to investigate whether age and photoperiodic conditions at different circadian stages could influence these fluctuations. Young mature (10 weeks) and old (22 months) Wistar rats were initially exposed to light-dark cycles 12:12 during 4 weeks, and secondly 18:6 for either one week or six weeks. Erythromycin N-demethylase (CYP3A-dependent), 7-ethoxycoumarin O-deethylase (CYP1A-dependent) and aniline 4-hydroxylase (CYP2E-dependent) activities were determined in liver and kidney microsomes at different hours after darkness onset (HADO). In addition, liver and kidney GSH, GSHPx, ATP, TBARS were determined. During the LD 12:12 cycle, while no significant modification was observed in CYP1A- and 2E-dependent enzyme activities as functions of HADO, erythromycin N-demethylase activity (CYP3A-dependent) showed a significant increase during the second third of the dark period in both young and old rats. After switching to a LD 18:6 cycle, this variation was still observed during second third of the dark period, to a lesser but still significant degree, with no difference between one week and six weeks exposure to the new photoperiod. It can be noted that the old rats showed a significantly lower level of erythromycin N-demethylase activity than the young rats, in parallel to a decrease in GSH, GSHPx and ATP, and an increase in TBARS. These results confirm the lower resistance of old animals to oxidative stress. The observed variations in metabolism parameters underline the need for study designs in pharmaco-toxicology taking into account the possible risks induced by circadian changes, especially in aged subjects.

Phalloidin hepatotoxicity in rats in vivo. Effect of a sympatholytic agent: propranolol.

Phalloidin, one of the main toxins of Amanita phalloides, induced hepatotoxicity in female Wistar rats at 0.9 mg/kg dose i.p. Biliary secretion was selectively inhibited after 3h, but was restored after 24 h. Phalloidin also induced a cytolytic lesion, but not a fatty liver, as in alpha-amanitin intoxication. Propranolol pretreatment (30 min prior to phalloidin injection) did not afford protection against hepatotoxicity, but increased alkaline phosphatase, 5'-nucleotidase and aminotransferase activities.

Ex vivo study on ATPase activities of rabbit renal proximal tubules as a predictive model for nephrotoxicity: Comparison with an in vitro study on a new cephalosporin (cefpirome).

An ex vivo study on adenosine triphosphatase (ATPase) activities of rabbit renal proximal tubules was conducted with a new cephalosporin, cefpirome (HR 810), a positive control, cephaloridine, and a reference third-generation cephalosporin, cefotaxime. Compared with controls, CPH caused a significant time-dependent decrease in ATPase activities [12%, 2 hr after treatment (P < 0.01) and 75%, 48 hr after treatment (P < 0.001)]. This decrease was accompanied by a significant loss in the energy charge of the adenylate pool [27%, 2 hr after treatment (P < 0.001)]. Neither cefotaxime nor cefpirome caused such decreases. The results confirmed those of a previously published in vitro study. The advantages and disadvantages of these two experimental procedures as predictive models for nephrotoxicity are discussed.

Effects of a new cephalosporin, cefpirome (HR 810), on ATPase activities of rabbit renal proximal tubule suspensions: Comparison with cephaloridine and cefotaxime.

The effect of cefpirome (HR 810), a new cephalosporin, on ATPase activities of rabbit renal proximal tubules has been measured and compared with that of cephaloridine and cefotaxime. Only cephaloridine, the nephrotoxicity of which is well established in the rabbit, produced after 60 min treatment a dose-dependent decrease in Na(+)/K(+)- and Mg(2+)-ATPase activities. Cefotaxime and cefpirome, which have a low nephrotoxic potential in the rabbit, did not exert any effect on ATPase activities.