A B S T R A C T S   N U M E R O   3 / 1999

Measurement of cyclosporin A in blood by SPE extraction and HPLC analysis

Giuseppe Dalmasso, Gaetano Magrė*
Laboratorio Analisi P.O. Imperia USL 1, Via S. Agata 57 (Responsabile Dott.ssa E. Bovina), Dipartimento di Patologia Clinica (Dott. C. Ruggeri)

Biochimica Clinica: 1999; 23(3): 123-126 [Article in italian]

ABSTRACT. Scope of this work was to assess the performance of simple, reproducible and low-cost method for the measurement of cyclosporin A (CyA) in blood by HPLC technique with UV detection, including SPE extraction and the use of cyclosporin D (CyD) as the internal standard added before extraction. The retention times of CyA (7.6 + 0.1min) and CyD (9.9 + 0.1min) showed reproducible, and the analysis time was 12 minutes. Linearity was shown up at least 3000 ng/mL, the detection limit was 12 ng/mL and mean recovery was 90%. Imprecision at two concentration values, as CV%, was in the interval 3.0 - 3.6% (in-the-series) and 7.8 - 82% (between-the series).

Serum sodium potassium measured by dry-chemistry tecnique: reference values for the Teatina population

Adele Rulli*, Corrado Romano, Gilda Angelini, Gabriella Odorisio, Giuseppe Nubile
Laboratorio di Analisi Chimico-Cliniche P.O. Clinicizzato SS Annunziata - Chieti

Biochimica Clinica: 1999; 23(3): 137-130 [Article in italian]

ABSTRACT. Aim of the present work was to assess the reference limits for serum sodium and potassium measured by the dry chemistry-based Vitros Instruments. A total of 2936 values for each analyte heve been considered, 2260 from in-patients (1127 F; 1133 M) and 676 from out-patients (384 F; 292 M). Compared to the reference limits suggested by the company, the observed frequency of values exceeding such Iimits was excessively hėgh, with special reference to in-patients. By applying non parametric statistical techniques to the sets of values from out-patients, we produced new reference limits, more suited to our population (teatina population).

Assessment of the analytical performance and practicability of a new automated chemistry system

Alberto Crippa*, Maurizio Parimbelli, Arialdo Vernocchi, Paolo Amboni
Ospedali Riuniti, Bergamo, Dipartimento di Patologia Clinica, Coordinatore: Prof. A. Parma

Biochimica Clinica: 1999; 23(3):131-139 [Article in italian]

ABSTRACT. The ADVIA® 1650 Chemistry System (Bayer Diagnostics, Tarrytown NY, USA) is a new random access analyzer characterized by a 3-second cycle, flexible pre-dilution concept, microvolumes of reagent, optional sample rack handler, state-of-art software, advanced optical system, and simple non-invasive connection to Lab Automation. We evaluated the analytical performance and the practicability of the system on 11 routine analytes in serum and, when appropriate, in urine samples. Within-run CV (modified NCCLS protocol) were lower than 1.5% with the exceptions of low concentrations of ALT and creatinine; overall CV were lower than 5% except for the low ALT and CK levels and the high ALP level in serum, and the low creatinine concentration in urine. All analytes under study proved linear up to or above the limit as programmed by the manufacturer, corresponding to several times their reference ranges. Regression coefficients of the system comparisons (vs. DAX 48 and Synchron CX7) ranged from 0.995 and >0,999; slopes ranged from 0.94 to 1.03 with serum analytes, with the exception of the a-amylase test for which the ADVIA 1650 uses a different substrate, and between 0.98 and 1.06 in urine assays, except for creatinine (b=1.13). All analytes tested showed a negligible sample-related carry-over, even in an extreme condition such as a sequence urine-serum, and a marginal reagent (probe-related) carry-over when ALT and LD were run in sequence without extra-wash. In the evaluation of practicability, most attributes fell between the areas ®Meeting requirements and ®Exceeding requirements. Attributes showing the highest scores and a marked upgrading over the current routine system were related to personal computer and software, volume and dilution of the sample, monitoring of instruments functions.

Plasma and peripheral blood mononuclear cell lactate dehydrogenase isoenzymes in normal subjects

Bianca Tripodi*, Fortunato Morabito1, Pasquale Borruto, Francesca Gangemi1, Pasquale Iacopino1, Francesco Meduri
Laboratorio Analisi: Dir. II livello Dott. Francesco Meduri
Azienda Ospedaliera Bianchi-Melacrino-Morelli, Reggio Calabria

Biochimica Clinica: 1999; 23(3):140-142 [Article in english]

ABSTRACT. In the present study plasma and peripheral blood mononuclear cell (PBMC) lactate dehydrogenase isoenzyme patterns were studied in 40 normal subjects by using an electrophoretic procedure. Our data show a significant prevalence of the LDH2 isoenzyme in plasma, while in the cellular pattern of PBMC the LDH3 isoenzyme prevails. However, each single isoenzyme, except the LDH5, showed in plasma a significantly different percentage as compared with the cellular pattern. Our study shows that LDH isoenzyme patterns may be determined in both plasma and PBMC extracts from normal subjects in a 5 mL blood sample in sodium citrate.

Clinical chemistry and renal function: new perspectives for the routinary estimation of the glomerular filtration rate

Michele Mussap*, Mario Plebani
Servizio di Medicina di Laboratorio, Azienda Ospedaliera di Padova

Biochimica Clinica: 1999; 23(3):143-160 [Article in italian]

ABSTRACT. Laboratory management of renal diseases is mainly performed by assessing the glomerular filtration rate (GFR). GFR is traditionally measured as the renal clearance of a particular substance from plasma and is expressed as the volume of plasma that can be completely cleared of that substance in a unit of time. In order to be accepted as ideal for the measurement of GFR, a substance must fulfill a set of requirements previously indicated by Homer Smith in 1955. Although the ideal marker for assessing GFR has yet to be found, these requirements can be useful benchmarks for comparing the advantages and disadvantages of new methods for GFR estimation. Human cystatin C has been recently proposed as a promising serum marker of changes in GFR. This low-Mr plasma protein is freeely filtered throught the glomerulus and almost completely reabsorbed and catabolized by the proximal tubular cells. It is constantly synthetized by all nucleated cells and its serum levels are not significantly influenced by sex, age, inflammation, body mass, physical activity, and diet. Several clinical studies have shown that cystatin C is more sensitive than serum creatinine for assessing small changes in GFR. This marker can be measured in the clinical practice by using fully automated immunological methods. In such conditions, i.e. in the neonatal period or in renal transplant patients, serum cystatin C may replace serum creatinine for the earlier assessment of changes in GFR.

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