Non-homogeneous separation of triglycerides, gamma-glutamyltransferase, C-reactive protein and lactate dehydrogenase after centrifugation of lithium-heparin tubes

BACKGROUND: Clinical chemistry testing is influenced by a variety of preanalytical variables, including sample preparation. The presence of a diluted plasma layer at the top of primary tubes containing plasma citrate has recently been reported. However, no indication is available so far on the potential non-homogeneous distribution of clinical chemistry analytes during centrifugation of primary tubes containing lithium-heparin as an additive. METHODS: A total of 40 lithium-heparin plasma samples were collected from volunteers and immediately centrifuged. An aliquot was obtained from the upper 0.4 mL of plasma (upper aliquot), 1.0 mL of plasma was discarded, and a second aliquot (lower aliquot) was obtained from the remaining plasma. The concentrations of alanine aminotransferase, albumin, alkaline phosphatase, amylase, amylase pancreatic, aspartate aminotransferase, direct bilirubin, total bilirubin, blood urea nitrogen, calcium, chloride, cholesterol, C-reactive protein (CRP), creatinine, creatine kinase, gamma-glutamyltransferase (GGT), glucose, high-density lipoprotein-cholesterol, iron, lactate dehydrogenase (LDH), magnesium, phosphate, potassium, total protein, sodium, triglycerides and uric acid were assayed on a Roche/Hitachi Modular System P according to the manufacturer's specifications and using proprietary reagents. Sodium, chloride and potassium were measured on a Roche/Hitachi Modular System using indirect ion-selective electrode methods. RESULTS: We observed a statistically significant difference between the upper and lower aliquots for CRP (3.88+/-0.67 vs. 3.94+/-0.68 mg/L; p=0.025), GGT (32.1+/-8.0 vs. 31.8+/-8.0 U/L; p=0.013), LDH (395+/-19 vs. 386+/-20 U/L; p=0.010) and triglycerides (1.29+/-0.09 vs. 1.27+/-0.09 mmol/L; p=0.001); results for the other analytes were not significantly different. In no case did the mean percentage bias recorded between aliquots exceed the current analytical quality specifications for desirable bias. CONCLUSIONS: The results of our investigation show that plasma layer stratification might occur in primary lithium-heparin tubes for a limited number of routine clinical chemistry tests, introducing a statistically significant bias in the measurement of GGT, LDH, triglycerides and CRP in the upper vs. the bottom section. When delayed testing is necessary for these parameters, we suggest that plasma should be separated after centrifugation and appropriately mixed before delayed/repeated analysis or aliquoting.     

Phlebotomy issues and quality improvement in results of laboratory testing

Laboratory testing is an integral part of the decision-making process, and results of laboratory testing often strongly influence medical diagnoses and therapies. There is a long history of quality requirements in laboratory medicine, which have mainly concerned the analytic phase of this process. Owing to the substantial advances in technology, laboratory automation and analytic quality, there is increasing evidence that further quality improvements should be targeted to extra-analytic phases of laboratory testing. Objective difficulties to monitor most of the preanalytic variables which lie outside the direct control or supervision of the laboratory personnel, such as phlebotomy, call for effective educational and preventive policies. Owing to high personnel turnover rates, lack of understanding about good laboratory practices, and inadequate training, there are several opportunities for making errors during phlebotomy, which mainly concern patient misidentification and collection of unsuitable specimens for testing due to unsuited venous accesses, venous stasis, inappropriate collection devices and containers. Improved standardization of phlebotomy techniques, along with operative guidelines dissemination, continuous education, certification, and training of health care professionals involved in blood drawing responsibilities would enhance the chance of obtaining specimens of consistent quality, with favorable revenues for the health care system and the patient's outcome.     

Evaluation of cardiac laboratory markers in patients with systemic sclerosis

OBJECTIVES: Myocardial involvement is frequent in systemic sclerosis, but symptoms are usually delayed and non-specific, thus often misrecognized. The aim of this study was the evaluation of the early subclinical cardiac involvement in patients with systemic sclerosis by means of non-invasive laboratory cardiac markers. DESIGN AND METHODS: Cardiac troponin T (cTnT), ischemia modified albumin (IMA) and NT-prohormone-brain natriuretic peptide (NT-proBNP) were measured in 40 female patients with systemic sclerosis and in 40 matched healthy controls. RESULTS: Patients with systemic sclerosis displayed significantly increased concentrations of serum IMA (106 versus 93.5 kunits/l, P < 0.0001) and NT-proBNP (89 versus 37 pg/ml, P < 0.0001), whereas no significant differences could be observed in both IMA and NT-proBNP values in limited versus diffuse pattern of disease. CONCLUSIONS: The increased levels of NT-proBNP and IMA could be considered a sign of early myocardial involvement, warranting further heart examination and a regular follow-up.     

中药材X-射线衍射图谱研究

为探讨中药材道地性的客观规律,以期建立相应的评估指标系统,本文选择常用中药材茜草类、贝母类、山药类三组样品,应用X-射线粉末衍射法进行图谱分析,获得了可用于标识中药材的衍射图形几何拓扑规律与图谱特征标记峰,由此观察到:不同产地茜草样品的相似性及其与欧茜草的差别;同属不同种贝母样品的相似性与差异;不同产地山药样品的相似性及与伪品的区别。本文结果预示着这一方法在揭示中药材道地性客观规律方面的广阔应用前景。     

高效液相色谱法对四种双氯灭痛软膏剂透皮效果的研究

目的：本实验采用高效液相色谱法,以离体小白鼠腹部皮肤为透皮屏障,比较了四种双氯灭痛软膏剂的透皮效果,方法：实验用法国Gilson公司的HPLC仪,以C18为固定相,甲醇－水（含HAc 0.36%)=80:20为流动相,紫外检测波长280nm。平均回收率为99．59％,RSD＜3．28％,检测限为1．0ug/ml。结果：1号样品透皮率最高,3号与1号相比较透皮吸收无显著性差异（P＞0．05）,2号或4号分别与1号相比,其透皮吸收均有显著性差异（P＜0．05）,结论：1号品值得进一步开发。     

依替菲宁的合成

目的：改进肝胆显像剂配基依替菲宁的合成方法。方法：该化合物以2,6－二乙基苯胺为原料,改进文献工艺制备而成。所得产物经红外光谱、核磁共振等分析确证结构。结果:工艺简单、产品易得、收率高于文献报道。结论：此合成路线完全可行。