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Errori di adattamento nell'utilizzo della funzione logistica a 4 parametri (4pl).Proposta di un modello di interpolazione sequenziale.

Vincenzo Miluccio¹, Adele Rolandi¹, Bruno Dente², Dario Spiteri^3
1Laboratorio Patologia Clinica - C.D. Molosiglio - Distretto 44 - ASL Napoli 1
²Laboratorio Patologia Clinica - Ospedale S.Paolo - ASL Napoli 1
³Laboratorio Patologia Clinica - Distretto 48 - ASL Napoli 1

Biochimica Clinica: 2004; 28(2): 227-235 [Article in italian]

ABSTRACT. Transformation of a scattering graphic in a continuous function is realized with different methods.Frequently the fitting does not result good, owing to not availability theoretical models able to explain in exhaustive way the biochemical procedure dynamics. 4PL, is considered a very useful and versatile model, for fitting immunometric dosages , for the generation of mathematical functions best litting signals/concentrationd pairs in immunoassay. How ever it, can originate bias making unreliable also the results from very good analytical systems. Statistical valutation and the search of a continuous graphic arised by two 4PL functions can eliminate or minimize bias.

Valutazione del metodo di 2^ generazione Innotrac Aio! per la determinazione della troponina I cardiaca

Franca Pagani, Francesca Stefini, Mauro Panteghini

Laboratorio Analisi Chimico Cliniche 1, Azienda Ospedaliera "Spedali Civili", Brescia

Biochimica Clinica: 2004; 28(2): 236-239 [Article in italian]

ABSTRACT. We evaluated the 2nd-generation cardiac troponin I (cTnI) assay performed on the Innotrac Aio! immunoanalyzer. The assay is based on "all-in-one" dry chemistry technology, in which all the reagents are pre-coated in assay cups (total analysis time of <20 min). The assay demonstrated a detection limit of 0.006 mg/L. Five cTnI-positive sera (native cTnI, 5 to 80 mg/L) were tested for linearity. For all samples, the hypothesis of a linear fit was accepted. In the imprecision study, the following results were obtained (mean cTnI, mg/L, and total CV): 0.019, 14.2%; 0.044, 8.2%; 0.065, 6.3%; 0.086, 6.3%; 0.14, 8.1%; 0.22, 6.0%; 0.39, 4.3%. Since a total CV â10% at the decision limit for myocardial infarction is recommended, the cTnI concentration corresponding to this imprecision was also derived (0.036 mg/L). 97% of cTnI values in 150 healthy subjects were <0.01 mg/L. The calculated 99th percentile of the value distribution was 0.015 mg/L. The Aio! 2nd-generation cTnI assay revealed improved performance and was close to meet the 10% CV at 99th percentile value, demonstrating a 10%/99th ratio of 2.4.

Valutazione Analitica del Metodo Turbidimetrico per Immunoglobuline Sieriche su Dimension Rxl

Francesca Di Serio, Luigia Loiodice, Lucia Varraso, Nicola Pansini

Laboratorio di Patologia Clinica I, Policlinico di Bari, piazza Giulio Cesare N.11 Bari

Biochimica Clinica: 2004; 28(2): 240-245 [Article in italian]

ABSTRACT. The purpose of our study was to assess, the analytical performance of the immunoturbidimetric Dimension RxL Immunoglobulins (Ig) assay. Calibration stability, precision, linearity and analytical sensitivity of the method were evaluated, and, the Ig immunoturbidimetric method was compared with the BN II Ig immunonephelometric method. Our data indicate that the Dimension RxL Ig assay is a sensitive, precise and linear method for the quantitative determination of Ig. Method comparison experiments showed a positive correlation; nevertheless Bland and Altman analysis revealed a disagreement between the two methods and a statistically significant bias was measured for IgG and IgA at low concentrations. In conclusion, our data suggest that the Dimension RXL Ig immunoturbidimetric method could be effective in the consolidation processes in the area of laboratory clinical chemistry, nevertheless the results related to low concentrations should be carefully evaluated.

Applicazioni cromatografiche nella determinazionedi alcuni farmaci antiepilettici

Giovanni Cangiano¹, Annachiara Latte², Marianna Boscaglia², Laura Marzillo², Enza Nigriello², Silvio Scoppa²,Andrea Risitano¹, Maurizio D'Amora²

Azienda Sanitaria Locale Napoli 1:1Laboratorio di Patologia Clinica - P.O. dei Pellegrini2Laboratorio di Patologia Clinica - P.O. S.M. del P. degli Incurabili

Biochimica Clinica: 2004; 28(2): 246-249 [Article in italian]

ABSTRACT. In this work two new chromatographic assays are presented for the measurements of lamotrigine and 10-oxi ferumal carbazepine: the former is performed in HPLC-UV technique with isocratic system in Chromat 3 reversed phase and latter with the Remedi multicolumn system. Measurements are easily performed more over, samples can be quickly assayed with the above mentioned instrumentation which is usually available in emergency sectors of clinical pathology aboratories : quick and effective therapeutic monitoring is possible iven if phenobarbital has been ossumed by the patient.

Sistema Menarini ADAMS 8160 per la rivelazione e misura delle frazioni emoglobiniche mediante cromatografia a scambio ionico HPLC: valutazione analitica

Roberta Martina Mozzi¹, Silvia Sarpau¹, Donatella Caruso², Flavio Giavarini², Carlo Franzini³

¹Laboratorio di analisi Chimico Cliniche, Ospedale L. Sacco, Milano
²Dipartimento di Scienze Farmacologiche, Facoltà di Farmacia, Università degli Studi di Milano
³Dipartimento di Scienze Cliniche Luigi Sacco, Facoltà di Medicina e Chirurgia, Università degli Studi di Milano

Biochimica Clinica: 2004; 28(2): 250-256 [Article in italian]

ABSTRACT. The evaluated system is a dedicated ion-exchange chromatography-based automated HPLC analyzer, allowing with a single short-time (4 minutes) run to measure both glycated haemoglobin (glycoHb), and minor (HbA2 and HbF) and variant haemoglobins in blood. Results were compared with those from the Bio Rad Variant and Variant II analyzers. In the glycoHb assay the evaluated system exhibited excellent precision (overall and within-the-series CV values in the interval 0.6 - 1.9 %); agreement with the comparison system was also good, showing mean underestimation of - 0.27 %Hb (- 3.86 %) at the decision level (glycoHb = 7.0 %Hb); the interference from carbamylated Hb (in vitro incubation with cyanate and uremic patients samples) appeared to be negligible if anY; and less pronounced than in the comparison system; no interference was recorded from very high concentrations of labile-glycoHb. HbF appeared to be precisely quantitated, with results in good agreement with the comparison system. Slightly higher imprecision (CV values in the interval 1.1 - 3.9 %) was observed in HbA2 assay; in the measurement of this last minor haemoglobin, agreement with the comparison was not quite satisfactory. The evaluated system failed in revealing 2 rare haemoglobin variants out of 46 rare and common variants tested. Hb testing with the Menarini ADAMS-8160 system showed excellent practicability. The advantages of performing with the same instrument different tests, relevant to different pathologies, are highlighted.

Procalcitonina: aspetti biochimici, metabolici, clinici ed analitici

Claudia Merlotti*, Paola Luraschi

*Università degli Studi di Milano, Scuola di Specializzazione in Biochimica ClinicaLaboratorio di Analisi Chimico - Cliniche, Ospedale L. Sacco, Milano

Biochimica Clinica: 2004; 28(2): 257-267 [Article in italian]

ABSTRACT. This review concerns calcitonin, as a plasma protein induced by infections. After a concise discussion of the molecule's biochemistry and metabolism, the clinical applications of its measurement in plasma are addressed, and the practical analytical problems concerning its measurement in clinical biochemistry laboratory settings are considered. The conclusion is drawn that plasma procalcitonin is characterized by stability and ability to change its plasma concentration following variations of the stimulus rising from infections and sepsis. Therefore, plasma procalcitonin level is a good marker for serious infetion/sepsis, mostly useful in children and in intensive care patients, where such pathological conditions may by recognised with difficulty by the more conventional markers of systematic inflammation.

NT-proBNP nella diagnosi differenziale di dispnea in pronto soccorso

Monica Mion¹, Masimo Forni¹, Sara Altinier¹, Martina Zaninotto¹, Mara Pastorello², Stefano Rocco², Mario Plebani¹

¹Servizio di Medicina di Laboratorio
²Servizio di Pronto Soccorso, Azienda Ospedaliera di Padova, Italia

Biochimica Clinica: 2004; 28(2): 268-271 [Article in italian]

ABSTRACT. The measurement of brain natriuretic peptide (BNP) in blood appears to be a sensitive and specific test for differentiating patient with congestive heart failure (CHF) from primary pulmonary causes of dyspnea in the emergency department (ED). The purpose of our study was to evaluate the clinical utility of the amino terminal fragment of the BNP pro-hormone (NT-proBNP) in the management of patients presenting to ED with dyspnea as main symptom. NT-proBNP was measured with an automated electrochemilumincscent immunoassay (Roche Diagnostics). Sensitivitv (SE) and specificity (SP) of NT-proBNP were calculated using peptide concentration results obtained from 23 patients (15 males, 62-92 years+8 females, 66-86 years) with (discarge diagnosis) congestive heart failure (CHF) and 11 patients (4 males, 62-90 years+7 females, 65-92 years) with chronic obstructive pulmonary disease (COPD) recruited at the ED of our hospital during the period 03/07/02-31/12/02. Comparing ED and discharge diagnosis, 4 patients resulted not correctly classified; NT-proBNP measured i these patients resulted inagreement with finsl diagnosis.

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