The influence of phthalate esters on human plasma lecithin/cholesterol acyltransferase.

The effect of various phthalate esters on the lecithin/cholesterol acyltransferase activity in man was studied in vitro. The enzymatic activity was strongly reduced with all phthalates except for the dimethyl phthalate. The inhibition rate depends on the phthalate concentration and also on the carbon number of the alkyl groups of phthalates.

The accuracy of the i-STAT portable analyser for measuring blood gases and pH in whole-blood samples from dogs.

To assess the suitability of the i-STAT portable analyser for use by non-laboratory personnel, we measured blood gases and pH in venous blood samples from 100 dogs. Deming's regression and bias plots were used to compare i-STAT results with those obtained by laboratory professionals using two different autocalibrated benchtop analysers. Overall accuracy of the portable analyser proved excellent for pH, pO(2), and pCO(2) (r=0.978, 0.968 and 0.997, respectively), with Deming's regression slopes close to 1.00 (0.96, 0.97 and 1.08 for pH, pO(2), and pCO(2), respectively) and intercepts close to zero (0.28, 0.47 kPa and 0.46 kPa for pH, pO(2), and pCO(2), respectively). The accuracy of the i-STAT was also satisfactory for calculated parameters: bicarbonates, total CO(2), base excess and oxygen saturation. Our findings show this portable analyser to be a valid substitute for expensive benchtop analysers in situations requiring mobility, or when small numbers of tests are to be performed by users not specialized in laboratory techniques.

[Assay of serum C-reactive protein. Comparison of 3 immunologic methods]. / Dosage de la protéine C-réactive sérique. Comparaison de trois méthodes immunologiques.

C-reactive protein is a parameter measured in ordinary laboratory routine and is frequently needed rapidly. The authors hereby compare three methods for the measurement of this protein using three common laboratory apparatus: TDX Abbott, BNA Behring and ICS Beckman. The experimental protocol used has been the one defined by the SFBC "Valtec" Commission. Regarding repeatability, the variation coefficients (CV%) are less than 10, except for a CRP value of 16 mg/l on TDX (19.3) and for a value of 56.4 mg/l on ICS (12.5). Reproducibility values confirm repeatability results in the case of TDX, while for ICS CV% are always less than 10. For values between 0 and 133 mg/l the authors have excellent linearity for the three apparatus tested (r = 0.99). The apparatus when compared two by two on 104 patient samples give linear allometric values and correlation coefficients are with acceptable limits (greater than 0.98). It must be noted that there is a difference between results obtained for patient samples and control sera when tested by the different apparatus. ICS necessitates daily calibration and gives the best values with control sera. With BNA the authors obtained more precise values and while TDX remains the easiest to handle, it gives unacceptable imprecise values for low CRP concentrations.

[Quality control of analyses and automation]. / Contrôle de qualité des analyses et automation

Multichannel analysers are becoming more and more usual in biochemistry laboratories. Then, a very severe quality control program is requisite. In Toulouse a three years experiment was carried out on a computer connected twenty four channels Autochemist and an unconnected Technicon SMA 12/60. The traditional quality control from control lyophilized serums is still necessary and useful, mainly at the level of a region. The remaining valuable methods are automatic calibration and statistical controls on frequently tested samples from human polled serum and on results from patients, these being provided through various procedures.

Ca2+ measurement with ion selective electrodes. The French coordinated evaluation of seven analyzers, for a better clinical relevance and acceptance.

The measurement of ionized calcium has evolved in the last decade, and can now be easily performed by clinical laboratories using direct potentiometric analyzers available from a number of manufacturers. An original protocol for a comparison of the analyzers was used through a parallel multicenter evaluation in France. Using newly developed aqueous buffered solutions, this study focused not only on the analytical performance and operational handling of analyzers, but also on possible interferences in biological samples and the clinical relevance of the measurement with respect to the techniques of sample collection. All the instruments exhibited good precision and linearity, and were easy to handle and robust for daily use. However, not all the models gave identical results on the same patient's specimen. The utility of some Ca2+ analyzers has been further enhanced by the ability to "correct" the results to pH 7.40, although care must be taken in the interpretation of these results. While there are a number of clear-cut situations in which Ca2+ measurement is more relevant than total calcium, it seems that chemical activity of Ca2+ in blood may sometimes be considered with great caution under pathological conditions. The role of Ca2+ measurement in routine will be discussed in relation to the potential benefits of the instruments in laboratories.

[Effect of phthalic esters on lecithin cholesterol acyltransferase]. / Effets des esters de l'acide phtalique sur la l'cithine-cholestérol-acyltransférase.

The in vitro effects of different esters of phthalic acid at increasing levels on the activity of LCAT have been studied using three currently known methods (Mickel and Foulds, Stokke and Norum, Alcindor). Inhibition from phthalates is high. It is proportional to the amounts used and in inverse ratio to the length of the carbon chains.

Evaluation of a cardiopulmonary preservation method for heart-lung transplantation.

This study was designed to examine whether concomitant administration of anti-free radicals with donorcore cooling on cardiopulmonary bypass (CPB) and hypothermic storage of the heart and lung, could provide successful extended cardiopulmonary preservation. Fourteen sheep heart-lung blocks harvested after core-cooling and cardioplegic arrest were preserved at 4 degrees C for 8.5 hr. Before and during CPB, the animals were perfused with Prostaglandin E1 (PGE1), superoxide dismutase (SOD), catalase (CAT) and deferoxamine (DEF). Cardioplegic arrest was induced with St. Thomas' Hospital solution (Plegisol) to which SOD, CAT and DEF had been added. The preservation solution consisted of Plegisol modified by the addition of K-lactobionate, raffinose, mannitol, SOD, CAT, DEF, a phosphate buffer and penicillin. Histological examination performed on 3 donor heart-lung blocks before and after CPB and cardioplegia, then immediately following cold storage, produced no clear evidence of structural damage in cardiac myocytes and lung parenchyma. Eleven donor organs were therefore transplanted in size-matched recipients with a total mean ischemic time of 12 hr. The combined administration of SOD, CAT, DEF, insulin and glucose during the initial period of reperfusion had no beneficial effect on cardiopulmonary performance. A progressive fall in Pa O2 and mean aortic pressure was observed post-operatively in the 7 animals that were weaned from CPB. Five of them died within 3 to 5 hr after CPB weaning, the remaining 2 animals died of cardiac arrest within the fourth hour. The results of this experiment seem to indicate that: 1. better organ function and improved survival could have been obtained if the duration of anti-radical treatment had been prolonged after reperfusion and, 2. physical manipulation of the donor grafts during harvesting and transplantation may have been partly responsible for the poor post-transplantation cardiopulmonary performance.

New in vitro assay based on glucose consumption for determining intraconazole and amphotericin B activities against Aspergillus fumigatus.

We developed a new in vitro method of evaluating antifungal molecules. Fungal growth was determined by measuring glucose consumption, the only carbon source in a synthetic medium. First, the growth of 12 Aspergillus fumigatus strains was studied. Glucose consumption was an excellent indicator of fungal growth. Second, the partial inhibition of growth was calculated in terms of the 90% or 50% inhibitory concentration for the 12 strains after treatment with itraconazole and amphotericin B. With a 3-day incubation time, the calculated 90% and 50% inhibitory concentrations agreed with those obtained by a macromethod and with those reported in previous publications. In each case the high degrees of efficacy of itraconazole and amphotericin B against A. fumigatus were confirmed. Partial inhibition induced by low concentrations of antifungal agents was quantifiable by this new method.

Assessment of recently developed blood gas analysers: a multicentre evaluation.

Providing guidelines for testing expected inaccuracy and imprecision is still a matter under debate. The Expert Panel of the French Society of Clinical Chemistry has developed a protocol, which was based on a comparative multi-centre evaluation of four instruments: the Ciba-Corning 278, the Instrumentation Laboratory 1306, the Nova SP 5 and the ABL 330. The purpose was to evaluate the analytical performance and efficiency of the analysers. Another aim was to design a valid approach for evaluating any new system. As buffered aqueous solutions and fluorocarbon emulsions give only partial information, tonometered blood was used at different levels of gas mixture, even though it is both difficult and time-consuming. Comparisons have been established on patients' blood samples with the analysers currently used in the evaluation sites. The tests showed that the four analysers have the same degree of precision, and interinstrument comparisons demonstrated a very high degree of reliability.This analysis emphasizes that the evaluation of instruments for pH and blood gas analysis is neither easy nor is it often done, mainly due to the choice of a quality-control material and the lability of the measured parameters.