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Biomedical subjects

M F Najjar

Publications and source records attributed to M F Najjar.

22 records · Page 2Linked to original sources
PubMedDate not supplied

[Adaptation of Biomerieux enzymatic UV ammonia on Konelab analysers].

INTRODUCTION: Circulating ammonia in normal patients is relatively low, despite the fact that ammonia is continually produced from endogenous amino acid metabolism. The physiopathological interest of plasmatic ammonia determination lies primarily in its relationships to hepatic insufficiency (cirrhotic or neoplasic), or the diagnosis and the forecast of the Reye's syndrome. OBJECTS: This study describes an evaluation of plasmatic ammonia determination by the UV end point enzymatic method using GLDH on KONELAB(TM) analyzers. METHODS: The glutamate dehydrogenase (GLDH : EC.1.4.1.3) catalyses the reducing amination of alpha-cetoglutarate in the presence of NH(4)(+) and of NADPH, H(+) to form glutamate and NADP(+). The reduction of NADPH,H(+)'s concentration, directly proportional to ammonia rates, is evaluated at 340 nm. All the conditions were met to optimize the method, while covering a satisfying field of measurement. RESULTS AND COMMENTS: The evaluation of the modified method showed a good precision (repeatability: CV < 4 %; interserial reproducibility: CV from 2.01 to 2.93 %; Intraserial reproducibility: CV equal to 0.67%) and a very good accuracy. The field of measurement extends from 27 to 250 micromol/L, with a limit of detection (L(D)) lowered to 0.325 micromol/L. CONCLUSION: The adapted technique is simple, fast, inexpensive and especially automatizable. It is in addition reliable and chiefly more sensitive, adapting particularly to the determination of plasmatic ammonia in urgency as in routine within our laboratory.

Ammonia↗
PubMedDate not supplied

[Evaluation of a spectrophotometric technique for plasmatic haemoglobin determination on Konelab 30].

INTRODUCTION: the measurement of plasma haemoglobin is utilized in the evaluation of various haemolytic phenomenons, especially at the time of sampling. Besides, the methods used to titrate plasmatic haemoglobin, an analysis which is of great interest to cardiac surgery, must be very accurate, because plasmatic levels are much lower than those found in whole blood. BACKGROUND: the purpose of this work is to present a new technique for direct determination of plasmatic haemoglobin. MATERIAL AND METHODS: this method was studied and adapted on a multiparametric analyzer Konelab 30 (Thermo Electron Corporation). The correlation was assessed with a Sigma Diagnostics spectrophotometric method, using the 3,3',5,5'-tetramethylbenzidine (TMB), a non carcinogenic reagent. The reaction of haemoglobin with TMB was studied with a SECOMAM S500P UV-Visible spectrometer. RESULTS AND DISCUSSION: the method demonstrates linearity, precision, and sensitivity suitable for clinical use and not affected by the presence of bilirubin, nor triglycerides. The method was precise (CV < 1,00%), accurate (CE < 5,00%) and showed excellent recovery of haemolysis (R > 0,95). The CV for the automated assay was less than 1%. Reference ranges were studied and lithium heparinate seems to be the best anticoagulant to use so as to minimize haemolysis. CONCLUSION: the studied technique is practical, specific, accurate, fast, reliable and inexpensive, and was adopted in emergency as in daily routine in our laboratory for plasmatic haemoglobin determination in various situations.

Hemoglobins↗