Abstract

         Background and Objectives: Concentration low-density lipoprotein (LDL) is one of the strongest indicators of atherosclerosis and predicts the diagnosis of cardiovascular diseases. LDL measurement accuracy is very important. LDL can be measured directly, such as enzymatic and nephelometry methods or can be calculated using Friedewald's formula. Despite the development of enzymatic methods and LDL nephelometry still in most laboratories is calculated using Friedewald's formula. The aim of this study was an investigation of correlation coefficient between two methods of measuring LDL- cholesterol levels.

         Methods: This descriptive cross-sectional study, performed on the 1141 patients. Cholesterol, triglycerides, HDL, LDL all patients assayed by enzymatic method. For patients with triglyceride levels of less than 400 mg/dl had LDL levels were calculated by Friedewald's formula. Normal levels of LDL/HDL ratio of less than 3.5 were considered.

          Results: Of the 1141 patients participating in this study, 38.3 % men and 61.7 % women. The mean patient age was 46.3 ± 16.1 years. Mean serum cholesterol, triglycerides and HDL were 177.9 ± 41.1, 132.9 ± 73.2 and 45.8 ± 13.2 mg/dl, respectively. Average direct and calculated LDL concentration was 82.1 ± 23.1 and 105.5 ± 35.8, respectively. The direct measurement of LDL, LDL/HDL levels in 97.1% of cases was normal, while 85.1 % of the calculation of LDL were normal. Pearson correlation coefficients were obtained by two methods: 0.869 (p <0.001).

         Conclusion: Despite the favorable correlation between two methods of measurements of LDL, the results of a calculation method is more than direct method. This can have a negative impact on the judgment of the treating physician.

           Key words: LDL, Enzymatic Method, Friedewald's Formula.

ABSTRACT

       Background and Objective: Measurement of amino acids is an important tool for metabolic studies and evaluation of patients’ clinical condition. The aim of this study was to analyze the plasma amino acids using reverse phase high performance liquid chromatography techniques (RP-HPLC) with pre-column derivatization by o-phthalaldehyde (OPA) in combination with 3- mercaptopropionic acid (3-MPA).

       Methods: Overall, 107 neonates and babies suspected of having metabolic disorder were enrolled in this study. The level of amino acids in plasma samples was analyzed within 65 minutes by HPLC with pre-column derivatization by OPA/3-MPA. This was a gradient RP-HPLC method that was performed using two solvents with a ratio of methanol and sodium acetate. L-norvaline internal standard was used as the reference peak for amino acids. Standard mixture of amino acids was used to determine the concentrations of amino acids.

        Results: According to the values of coefficient of variation obtained for each amino acid, the results indicated a good chromatographic separation of amino acids by this method. The use of OPA/3-MPA derivative reagent increased the efficiency and resolution of amino acids chromatographic separation.

      Conclusion: Due to simple preparation and accurate assessment, determination of plasma amino acids using OPA/3-MPA derivatives and RP-HPLC is a suitable method in many clinical samples.

ABSTRACT
          Background and Objectives: The incidence rate of esophageal cancer (EC) is high in north and northeast of Iran. Taurine is a sulfur-containing amino acid with a wide range of vital biological functions. The aim of this study was to compare plasma levels of taurine between patients with EC and healthy controls.
        Methods: Plasma samples from 36 recently diagnosed cases of EC and 36 healthy adults were analyzed by high-pressure liquid chromatography. Data analysis was done using SPSS (version 16). The t-test was used to evaluate significant differences in the level of taurine between the two groups. P-values less than 0.05 were considered statistically significant.
         Results: Patients with EC had significantly higher levels of plasma taurine compared with the controls (P<0.05).
         Conclusion: Patients with EC have significantly higher levels of plasma taurine compared with healthy individuals. This finding suggests that the measurement of plasma taurine in patients with EC could be useful for the early diagnosis of the disease.
        Keywords: Esophageal Cancer, Taurine, HPLC.