Biomedical subjects

Roberto Chessa

Publications and source records attributed to Roberto Chessa.

4 recordsLinked to original sources

PubMed2006

Assay for the simultaneous determination of guanidinoacetic acid, creatinine and creatine in plasma and urine by capillary electrophoresis UV-detection.

Guanidinoacetic acid (GAA) measurement has recently become of great interest for the diagnosis of creatine (Cn) metabolism disorders, and research calls for rapid and inexpensive methods for its detection in plasma and urine in order to assess a large number of patients. We propose a new assay for the measurement of GAA by a simple CZE UV-detection without previous sample derivatization. Plasma samples were filtered by Microcon-10 microconcentrators and directly injected into the capillary, while for urine specimens a simple water dilution before injection was needed. A baseline separation was obtained in less than 8 min using a 60.2 cm x 75 microm uncoated silica capillary, 75 mmol/L Tris-phosphate buffer pH 2.25 at 15 degrees C. The performance of the developed method was assessed by measuring plasma creatinine and Cn in 32 normal subjects and comparing the data obtained by the new method with those found with the previous CE assay. Our new method seems to be an inexpensive, fast and specific tool to assess a large number of patients both in clinical and in research laboratories.

Creatine↗

PubMed2005

Plasma creatinine and creatine quantification by capillary electrophoresis diode array detector.

Traditional clinical assays for nonprotein nitrogen compounds, such as creatine and creatinine, have focused on the use of enzymes or chemical reactions that allow measurement of each analyte separately. Most of these assays are mainly directed to urine quantification, so that their applicability on plasma samples is frequently hard to perform. This work describes a simple free zone capillary electrophoresis method for the simultaneous measurement of creatinine and creatine in human plasma. The effect of analytical parameters such as concentration and pH of Tris-phosphate running buffer and cartridge temperature on resolution, migration times, peak areas, and efficiency was investigated. Good separation was achieved using a 60.2-cm x 75-microm uncoated silica capillary, 75 mmol/L Tris-phosphate buffer, pH 2.25, at 15 degrees C, in less than 8 min. We compared the present method to a validated capillary electrophoresis assay, by measuring plasma creatinine in 120 normal subjects. The obtained data were compared by the Passing-Bablok regression and the Bland-Altman test. Moreover the performance of the developed method was assessed by measuring creatine and creatinine in 16 volunteers prior to and after a moderate physical exercise.

Adult↗

PubMed2005

Thiol redox status evaluation in red blood cells by capillary electrophoresis-laser induced fluorescence detection.

Thiols and in particular glutathione (GSH) play a central role in human metabolism, including the detoxification of xenobiotics, cell homeostasis, radioprotection, and antioxidant defence. Here, a new method is provided for the measurement of reduced and total forms of thiols in red blood cells. In order to minimize oxidation of reduced thiols, a water erythrocyte lysis (15 min at 4 degrees C) was performed followed by a protein precipitation step with acetonitrile. The supernatant was rapidly derivatized with 5-iodoacetoamidefluorescein that trapped thiol groups, thus minimizing auto-oxidation. Derivatized samples were separated in a 57 cm x 75 microm ID capillary by using 5 mmol/L sodium phosphate, 4 mmol/L boric acid as electrolyte solution with 75 mmol/L N-methyl-D-glucamine at pH 11.0. Under these conditions, cysteinylglycine (CysGly), cysteine (Cys), glutathione, and gamma-glutamylcysteine (GluCys) were baseline-resolved in approximately 4 min. Precision tests showed a good repeatability of our method both for migration times (coefficient of variation CV < 0.8%) and areas (CV < 3.3%). Furthermore, a good reproducibility of intrassay and interassay tests was obtained (CV < 5% and CV < 8%, respectively). The method was employed to investigate the effect of acidic precipitation on intracellular thiol concentration. Our data suggest that sample acidification causes a modification of the measured redox thiol status due to the development of a pro-oxidant environment; moreover, the thiol redox status of red blood cells was evaluated in 22 healthy volunteers.

Electrophoresis, Capillary↗

PubMed2005

Carotid narrowing degree and plasma thiol levels in carotid endarterectomy patients.

The aim of this work was to study the association between plasma thiol levels and percentage carotid narrowing in a group of 68 patients who underwent a carotid endarterectomy, pertained as a risk factor for vascular and cardiovascular disease. Total plasma thiols were measured by capillary electrophoresis laser-induced fluorescence. The mean values of the hematological parameters studied were within normal limits and 25% of the patients were hyperhomocysteinemic (homocysteine >15 micromol/L). Pearson's correlation between carotid narrowing degree and the most common risk factors for atherosclerosis showed a positive relationship only between carotid narrowing degree and cysteine levels (r=0.252; p<0.05). Stepwise multiple linear regression with carotid narrowing degree as the dependent variable, and cysteine, homocysteine, age, triglyceride and low-density lipoprotein-cholesterol as independent variables confirmed that cysteine was significantly associated with these variables. By regrouping the population according to cysteine and homocysteine concentration percentiles, we found positive correlation between these parameters and median values of carotid narrowing degree. Our study provides experimental evidence to confirm that plasma homocysteine and cysteine are involved in carotid narrowing after carotid endarterectomy intervention, suggesting that cysteine may be involved in the deleterious molecular mechanisms active in carotid stenosis.

Aged↗