Commutability of calibration and control materials for serum lipase

Background: To effectively assess and correct for intermethod variability, calibration and control materials (CCMs) must show the same intermethod behavior as patient sera, i.e., they must be commutable. We describe the commutability of selected CCMs for lipase assays, the impact of noncommutability of CCMs in normalizing patient results, and characteristics of reagents that affect assay specificity and commutability. Methods: Lipase was measured in 98 patient sera and in 29 commercial CCMs, with 2 commercial methods using different substrates and with 4 experimental methods using 1,2-o-dilauryl-rac-glycero-3-glutaric acid-(6\u2032-methylresorufin) ester as substrate and colipase as cofactor, but differing in the stabilizing proteins used and in the size of the substrate micelles. Results: The noncommutability rate, i.e., the frequency of aberrant intermethod behavior of CCMs in comparison with patient sera, was 27% for liquid CCMs and 47% for lyophilized CCMs. The normalized residuals, measuring the degree of noncommutability, were -2.3 to 2.4 for CCMs with "normal" lipase activity, and -3.5 to 21.7 for CCMs with higher lipase activity. Recalculation of patient results with CCMs as calibrators decreased or increased the original bias according to whether the CCMs were commutable. Conclusions: For the lipase methods in this study, the frequency of noncommutability of CCMs is affected by assay-specific characteristics, including size of substrate micelles and the presence or absence of added proteins

Stabilty Constants of Haemiglobin Cyanide and Azide Measured by Two-Wavelength Spectrophotometric Method

A two-wavelength spectrophotometric procedure for the simultaneous determination of haemiglobin and haemiglobin cyanide (HiCN( (or of haemiglobin and haemiglobin azide (HiN3)) concentrations in mixtures has been developed and applied to the determination of the stability constants of HiCN and HiN3. The analytically reliable procedure allowed stablity constants to be estimated with about 10% (relative standard deviation, coefficient of variation) uncertainty.Peer Reviewe

Myoglobin and creatine kinase isoenzyme MB mass assays: intermethod behaviour of patient sera and commercially available control materials

The low biological variation of myoglobin and creatine kinase isoenzyme MB mass (CK-MBm) requires accurate measurements. In the standardization process, in order to effectively measure and correct intermethod variability, the intermethod behaviour of control materials must be the same of patient sera, i.e. they must be commutable. In this work we checked the commutability of some commercially available control materials in pairs of methods for myoglobin and CK-MBm measurements; we assessed the impact of commutable and non-commutable control materials when used for equalizing patient sera results by two different methods and discussed the problems related to external quality assessment schemes. Myoglobin and CK-MBm were measured in sets of 49 and 56 patient sera and in 13 commercially available control materials with two automatic analytical systems. The non-commutability rate was 8.3% for myoglobin and 23.1% for CK-MBm. Recalculation of serum samples results with a control material as calibrator lowered or increased the bias originally present according to whether the material itself was commutable or not. We conclude that also for myoglobin and CK-MBm assays it is necessary to check the commutability of materials to be used in external quality assessment schemes, or to normalize patient results by different methods

L'aerosolizzazione può ancora essere ritenuta una metodica valida per la sanificazione dell'aria in ambienti confinati?

Lo scopo del presente lavoro è stato quello di valutare l’efficacia di due differenti disinfettanti (un complesso iodato di nonil fenossipoliglicoletere e un complesso di potassio perossimonofosfato) aerosolizzati nell’aria per mezzo di un aerosolizzatore Felmar 745 sulla riduzione della carica microbica presente nell’aria in ambulatori di una clinica. I nostri risultati sembrano dimostrare che dopo il trattamento aerosolico dell’aria con questi disinfettanti si è avuta una riduzione media superiore al 73%. Si può quindi concludere che l’aerosolizzaazione mediante un complesso iodato di nonil fenossipoliglicoletere o un complesso di potassio perossimonofosfato determina una buona disinfezione dell’aria degli ambienti confinati

Enhancement of HSV-DNA infectivity, in Vero and RS cells, by a modified calcium-phosphate transfection technique

Infectivity of herpes simplex virus (HSV) DNA was assessed by employing the calcium-phosphate transfection technique described by Chen and Okayama, originally applied to increase the efficiency of plasmid transfection by N, N-bis (2-hydroxyethyl)-2-aminoethane sulfonic acid (BES). The experimental conditions and efficiency of this transfection procedure were evaluated comparing the viral progeny titers obtained by the Chen and Okayama transfection method using DNA from wild-type strains of HSV-1 and HSV-2, as well as from mutant strains, with the viral progeny obtained by the most widely used transfection technique introduced by Graham and van der Eb. Furthermore, recombinant virus production was evaluated in marker transfer and marker rescue experiments, comparing both transfection techniques, using DNA fragments cotransfected with whole viral DNA into African green monkey (Vero) or rabbit skin (RS) cells. The viral production obtained from HSV-DNA transfected cells was enhanced approximately 1000-fold when the Chen and Okayama procedure was applied

[Quality control of mammography: potential use of a new device for testing the image quality and the dose].

The authors tested a new equipment containing a phantom to check quality mammographic image and an electronic instrument to measure incident radiation (Phan-EX). The phantom contains objects which have similar characteristics to the details of diagnostic interest and allows an easy and accurate estimation of image quality on the basis of the number of objects detected. The radiation detector, consisting of a solid state photodiode, provides an integer proportional to the input exposure. The results obtained highlighted a good reproducibility of instrument output and a good relationship between these values and the exposure ones obtained with a much more expensive ionization chamber. The device response was linear in varying both the anodic exposure (mAs) and the x-ray tube voltage (varying the energy, the calibration factor varied only by a small percent). The authors conclude that the Phan-EX may be useful for quality assurance of the mammographic unit. Furthermore, they suggest some of its practical applications: daily tests of qualitative of the mammographic unit and the treatment system performance, control of the automatic exposure probe, choice and optimization of exposure and treatment of the film parameters, the determination of the output of the x-ray tube, the evaluation of the sensitivity of different screen/film system