In vitro detection of indirect-acting genotoxins in the comet assay using Hep G2 cells

The induction of DNA damage by four known promutagens (cyclophosphamide (CP), benzo(a)pyrene (BP), dimethylbenz(a)anthracene and 2-acetylaminofluorene (2AAF) was investigated on Hep G2 using the alkaline single cell electroporesis (SCGE) test, most often referred as the "comet assay". After a 3-day incubation, lysed cells embedded in agarose were electrophoresed under alkaline conditions, dyed with a SYBRgold fluorogen and analysed by the Komet software. Among the comet parameters provided by the image analysis program, statistical analysis did not identify any in particular that could best represent the DNA damages. All promutagens, when compared with the control, caused a statistically significant increase in DNA migration as determined by different parameters such as Olive tail moment, tail extent moment, tail/head or tail length. The data demonstrated the ability and the sensitivity of the comet assay when performed on Hep G2 in the detection of DNA damage induced by promutagens, and its suitability in mutagenicity testing in in vitro short-term assays.

Tau and apo E in CSF: potential aid for discriminating Alzheimer's disease from other dementias

To evaluate the usefulness of tau proteins as biological markers in the diagnosis of dementia of the Alzheimer type (DAT), we analyzed the concentration of tau proteins in 253 cerebrospinal fluid (CSF) samples from patients with or without neurological disorders. Our study showed a significant increase of the mean CSF tau concentration in DAT patients compared with that from non-DAT patients. Interestingly, a significative decrease of CSF tau in patients with frontotemporal dementia was found. We also observed a positive correlation between the CSF-tau concentration and the number of apoepsilon4 alleles. The CSF apolipoprotein E concentration was evaluated and revealed no variation between the groups, although we observed a significant correlation between CSF tau and apolipoprotein E in DAT patients.

Direct coronary stenting without balloon predilation in acute coronary syndromes

BACKGROUND

This prospective, observational study was designed to evaluate the feasibility and the safety of a new strategy for stenting in acute coronary syndromes: direct stent implantation without predilation of the culprit lesion. This strategy might reduce both the cost of the procedure and the rate of no-reflow, a phenomenon that is more frequently observed during dilation of unstable plaques.

METHODS AND RESULTS

Between September 1997 and March 1998, 122 carefully selected patients with unstable angina or acute myocardial infarction were included in this study. Highly calcified lesions and vessels with excessive proximal tortuosity were excluded. The procedure was successful in 96% of cases. In 5 cases the stent failed to pass through the stenosis and was successfully retrieved in the guiding catheter in 3 cases. In 2 cases the stent was lost in the peripheral circulation. Transient no-reflow occurred in only 3 cases and was rapidly reversed by rescue use of an intracoronary bolus injection of a glycoprotein IIb/IIIa receptor inhibitor in 2 cases. A patient treated by primary angioplasty with cardiogenic shock on admission died 48 hours after the initial procedure because of irreversible cardiac failure. One-month clinical follow-up was obtained by telephone for all patients; no major coronary events occurred during this period.

CONCLUSIONS

Direct coronary stenting without balloon predilation can be safely performed in acute coronary syndrome-related lesions in selected patients. A randomized, controlled study is warranted to confirm the promising results of this pilot study, especially regarding the low rate of the no-reflow phenomenon.

A new approach for clinical biological assay comparison and standardization: application of principal component analysis to a multicenter study of twenty-one carcinoembryonic antigen immunoassay kits

BACKGROUND

Principal component analysis (PCA) is a powerful mathematical method able to analyze data sets containing a large number of variables. To our knowledge, this method is applied here for the first time in the field of medical laboratory analysis.

METHODS

PCA was used to evaluate the results of a blind comparative study of 21 carcinoembryonic antigen (CEA) reagent kits used to determine CEA concentration in a panel of sera from 80 patients.

RESULTS

The mathematical technique first eliminated the variations attributable to the use of different calibrators. The PCA representation then gave a global view of the dispersion of the kits and allowed the identification of a main homogeneous group and of some discrepant kits.

CONCLUSIONS

PCA applied to the in vitro diagnostic reagent field could contribute to the standardization process and improve the quality of medical laboratory analyses. A standardization method using a panel of patient sera is proposed.

[Comparison of in vitro activity of six disinfectants on bacteria from contamination in hemodialysis water]

The bactericidal and sporicidal activities of six disinfectants were compared in vitro by determination minimal bactericidal concentrations from AFNOR standards for antiseptics and disinfectants. These disinfectants were tested against seventeen bacterial strains and two suspensions of spores including reference strains and wild strains from water of hospital environment. The compound with peracetic acid, ACETOPER 200, is the only disinfectant with the two activities against all strains at 21 degrees C +/- 1 degree C in short length of time. Furthermore except for Serratia liquefaciens that is remarkably resistant to STERLANE, no significant differences of susceptibility to disinfectants appear between wild bacterial strains and reference strains.

Inhibition of gastric acid secretion by oxyntomodulin and its 19-37 fragment in the conscious rat

Oxyntomodulin (Oxm) is a hormone, released from the intestine during digestion. Its target tissue is the gastric mucosa, where it inhibits acid secretion. It contains the 29-amino acid glucagon moiety, extended at its COOH-terminal end by an octapeptide. The glucagon moiety contains a basic doublet (Arg17-Arg18). Our working hypothesis was that the mode of action of Oxm may imply a processing of the molecule at the Arg-Arg doublet, releasing Oxm-(19-37). We compared the effect of Oxm with that of Oxm-(19-37) on gastric acid secretion in the conscious rat provided with a chronic gastric fistula. The acid secretion was plateau stimulated by a perfusion of either pentagastrin or histamine. Whereas Oxm or Oxm-(19-37) had no effect on basal acid secretion, both peptides inhibited pentagastrin (0.5 micrograms.kg-1.h-1)- and histamine (0.4 mg.kg-1.h-1)-stimulated acid secretion in a dose-dependent manner. When the metabolic clearance rate for each peptide was taken into account, the 19-37 fragment was as potent as the whole Oxm, regardless of the type of stimulant. When the dose of pentagastrin was increased from 0.175 to 1.1 micrograms.kg-1.h-1, the extent of inhibition induced by Oxm (40 pmol/kg) also increased. In contrast, when the dose of histamine was increased from 0.25 to 1.2 mg.kg-1.h-1, the extent of inhibition induced by Oxm (40 pmol/kg) decreased. Oxm-(19-37) (70-140 pmol/kg) displayed the same behavior as the whole molecule under both types of stimulation.(ABSTRACT TRUNCATED AT 250 WORDS)

Dose-related effect of moxisylyte on maximal urethral closing pressure in patients with spinal cord injuries

The effects of single intravenous doses of 0.25, 0.50, and 0.75 mg/kg moxisylyte on maximum urethral closure pressure were evaluated in a placebo-controlled double-blind experiment in 20 patients with spinal cord injuries. Pharmacodynamic testing was performed until 30 minutes, and blood pressure was assessed until 60 minutes. Our findings showed a dose-dependent decrease in maximum urethral closure pressure. At each individual time point, the three doses differed significantly from placebo. Ten minutes after dose administration the maximum effect (48% decrease) was obtained with 0.75 mg/kg. A significant difference in favor of the highest dose was shown from 15 to 20 minutes after administration. According to these findings and because 0.75 mg/kg was as well tolerated as the two other doses, such a drop in pressure indicates that the alpha-blocking agent moxisylyte may be an effective means of decreasing urethral resistance, with obvious implications for the management of urinary obstruction.

[Dysregulation of plasma 1,25(OH)2D in calcium restriction in hypercalciuric children]

BACKGROUND

The effect of calcium restriction on the plasma concentration of 1,25(OH)2D in normo- and hypercalciuric children remains unknown.

METHODS

We studied phosphate and calcium metabolism of 8 normocalciuric and 8 hypercalciuric children aged 4 to 16 years, under 3 conditions: on a normal dietary calcium intake after a 5-day calcium-restricted diet, and after oral calcium loading. The healthy, normocalciuric children had histories that included no renal failure of abnormalities of phosphate and calcium metabolism. Four of the 8 hypercalciuric children had urolithiasis, 1 had hematuria and the 3 others had idiopathic hypercalciuria. Blood samples were analyzed for calcium, creatinine, immunoreactive parathyroid hormone, cAMP, 25(OH)D and 1,25(OH)2D concentrations. Urine samples were analyzed for calcium, phosphorus, creatinine and cAMP.

RESULTS

On the normal dietary calcium intake, the hypercalciuric children had higher urinary calcium excretion and plasma 1,25(OH)2D levels and lower TmP that did the controls. The 1,25(OH)2D levels of the normocalciuric children were significantly increased after 5 days of dietary calcium deprivation, but those of the hypercalciuric children were not. The other parameters (essentially PTH, cAMP and TmP) varied similarly in the two groups.

CONCLUSION

The results suggest that: a) calcium restriction influences 1,25(OH)2D levels in normocalciuric subjects via a PTH- and phosphor-independent mechanism; b) dietary control of renal vitamin D metabolism is impaired in hypercalciuric patients.

Bioluminescence: an improvement in the enzymatic assay of dehydroepiandrosterone sulfate in biological fluids

Dehydroepiandrosterone sulfate (DHEAS) determination in biological fluids was carried out by enzymatic hydrolysis and conversion into estrogens [estrone (E1) and estradiol (E2)] by the multienzyme system of human placental microsomes. The enzymatic complex consists of sulfatase, 3 beta-hydroxysteroid oxido reductase and 5en----4en isomerase which converts DHEAS into androstenedione (A); the latter component is further converted into estrogens by the aromatase. The resulting estrogens were determined from the NADH formed by the transhydrogenation reactions of human placental dehydrogenase. NADH was measured by bioluminescence. As little as 4 pg was assayable by this rapid enzymatic method, with a coefficient of variation of 8%. The results are in good agreement with radioimmunoassay and the method is suitable for routine use.

Quantitative thin-layer and high-performance liquid chromatographic determination of lorapride in biological fluids and a pharmacokinetic study in humans

Lorapride has been determined in plasma, red blood cells, and urine by HPLC. The detection was performed at a short wavelength (226 nm), resulting in a detection limit of 10 ng/mL (amount injected was 3.5 ng). Reproducibility of analytical and chromatographic methods through statistical coefficients of variation was 4%. By TLC, only levels in urine were determined. Urine samples were spotted directly on the plate; lorapride was determined after spraying the plate with the Bratton-Marshall reagent, and measurements were carried out in the simultaneous reflectance and transmittance mode (540 nm). The detection limit was 10 ng spotted. Lorapride amounts in urine determined by the two methods were compared by statistical analysis. Examples of kinetics after intravenous and oral administration (100 mg) in humans are given.