Hepatitis B e antigen levels and response to peginterferon: influence of precore and basal core promoter mutants.

Hepatitis B e antigen (HBeAg) levels may predict response to peginterferon (PEG-IFN) but are also influenced by presence of precore (PC) and core promoter (BCP) mutants. HBeAg was measured in 214 patients treated with PEG-IFN±lamivudine for 52weeks. Patients were classified at baseline as wildtype (WT) or non-WT (detectable PC/BCP mutants).

Close monitoring of hepatitis B surface antigen levels helps classify flares during peginterferon therapy and predicts treatment response.

Background: Alanine aminotransferase (ALT) flares occur frequently during peginterferon (PEG-IFN) therapy. We related occurrence of flares to presence of precore (PC) and/or basal core promoter (BCP) mutants and studied kinetics of hepatitis B e antigen (HBeAg) and hepatitis B surface antigen (HBsAg) levels during flares.

Methods: Fifty of 214 (23%) patients treated with PEG-IFN ± lamivudine for 52 weeks experienced flares.

A comparison of two assays for quantification of Hepatitis B surface Antigen in patients with chronic hepatitis B.

Background And Objectives: Serum Hepatitis B surface Antigen (HBsAg) levels correlate with hepatitis B virus intrahepatic covalently closed circular DNA and may predict response to treatment. Currently, 2 commercial platforms are available for HBsAg quantification in clinical practice, the Architect HBsAg QT and the Elecsys HBsAg. We aimed to directly compare the results of these assays.

The association of the dopamine transporter gene and the dopamine receptor 2 gene with delirium, a meta-analysis.

Delirium is the most common neuropsychiatric syndrome in elderly ill patients. Previously, associations between delirium and the dopamine transporter gene (solute carrier family 6, member 3 (SLC6A3)) and dopamine receptor 2 gene (DRD2) were found. The aim of this study was to validate whether markers of the SLC6A3 and DRD2 genes are were associated with delirium in independent populations.

Atorvastatin affects low density lipoprotein and non-high density lipoprotein cholesterol relations with apolipoprotein B in type 2 diabetes mellitus: modification by triglycerides and cholesteryl ester transfer protein.

Objectives: Non-HDL-cholesterol (non-HDL-C) and apolipoprotein (apo) B are proposed as treatment targets. The extent to which statin therapy affects relationships of LDL-C and non-HDL-C with apoB was examined in type 2 diabetes.

Methods: Analyses were performed in 217 hypertriglyceridaemic type 2 diabetic patients (Diabetes Atorvastatin Lipid Intervention (DALI) cohort).

Optimization of apolipoprotein(a) genotyping with pulsed field gel electrophoresis.

Background: Increased lipoprotein(a) is a risk factor for atherosclerosis, and its concentration in serum is inversely correlated with the size of the apoliprotein(a) [apo(a)] component. The size of the apo(a) gene is determined mainly by the Kringle IV size polymorphism. We have optimized and characterized pulsed field gel electrophoresis (PFGE) for apo(a) genotyping.

Survey of total error of precipitation and homogeneous HDL-cholesterol methods and simultaneous evaluation of lyophilized saccharose-containing candidate reference materials for HDL-cholesterol.

Background: Standardization of HDL-cholesterol is needed for risk assessment. We assessed for the first time the accuracy of HDL-cholesterol testing in The Netherlands and evaluated 11 candidate reference materials (CRMs).

Methods: The total error (TE) of HDL-cholesterol measurements was assessed in native human sera by 25 Dutch clinical chemistry laboratories.

Reference standardization and triglyceride interference of a new homogeneous HDL-cholesterol assay compared with a former chemical precipitation assay.

A homogeneous HDL-c assay (HDL-H), which uses polyethylene glycol-modified enzymes and sulfated alpha-cyclodextrin, was assessed for precision, accuracy, and cholesterol and triglyceride interference. In addition, its analytical performance was compared with that of a phosphotungstic acid (PTA)/MgCl2 precipitation method (HDL-P). Within-run CVs were < or = 1.

Validation of a natural urinary stone data based infrared library searching system with artificial survey samples.

In this study we evaluated a Fourier transform IR spectrometer (Bio-Rad, USA) equipped with a search system for the analysis of urinary stones. We constructed a database of the stone library with the help of results found with X-ray diffraction analysis. In total, we included 223 stone results (213 natural and 10 spurious stones) consisting of single and composite nature.

The transferability of a candidate reference method for determination of creatinine in serum.

We developed a candidate reference method for the determination of creatinine in serum. For the acceptance of a reference method it is important that it be rigorously validated against a definitive method and that the method can be transferred from one laboratory to another. This study focussed on the transferability and consisted of two parts: introduction and familiarization with the method in four clinical chemistry laboratories in the Netherlands, followed by independent measurements of Standard Reference Material 909a2 and several commercial quality control materials provided with reference method values according to the protocol of the German Quality Assessment Organisation.

Phenotyping and genotyping of coagulation factor V Leiden.

The currently used activated Protein C resistance test demonstrated to be of limited diagnostic value for the detection of the mutant Factor V Leiden. Moreover, this assay is not useful for patients under anticoagulant therapy. A modification of the APC resistance test, applying Factor V deficient plasma is described which demonstrates a specificity and sensitivity of 1.

Effect of pH on absorption of sufentanil citrate in a portable pump reservoir during storage and administration under simulated epidural conditions.

Sufentanil (5 micrograms/ml as citrate) was investigated for its stability when diluted with sodium chloride 0.9%, in 100 ml polyvinyl chloride portable pump reservoirs during administration under simulated epidural conditions at 32 degrees C for 48 h. Sufentanil was absorbed into the polyvinyl chloride, resulting in a reduction of 10.

Serum creatinine and the DuPont dimension: possible improvements.

A study is reported on the determination of creatinine with the DuPont Dimension, paying special attention to interference by bilirubin. Various methods for dealing with bilirubin interference are described, including modification of the Jaffé reaction, enzymatic assay of creatinine, enzymatic destruction of bilirubin, and ultrafiltration of the serum sample. None of these modifications gave completely satisfactory results, although the Jaffé method with a ferricyanide oxidation step, and the enzymatic assay with ferrocyanide gave reasonable results with icteric specimens from adult patients, while only the latter method could be used for neonatal serum samples.

New approaches with the Chem-1 creatinine determination.

Three modifications of the Chem-1 determination of serum creatinine were tested. Two different algorithms developed for compensating the interference of bilirubin were compared with the current one by analysing bilirubin-enriched albumin solutions and 82 icteric serum samples. A number of known other interfering substances were also tested.

Validation of the ultrafiltration technique for creatinine analysis by HPLC: a comparison with direct serum injection.

The determination of creatinine by HPLC was performed by direct injection of serum onto the column, and after ultrafiltration of the sample, and the results were compared. A modified weak cation exchange column was used for HPLC. This eliminates the protein displacement effect and the Gibbs-Donnan effect, thus permitting a rapid direct analysis.

Creatinine and automatic analysers in relation to icteric specimens.

A study is described on the interference of bilirubin with the determination of creatine in serum using three automatic analysers i.e. the Technicon Chem-1, the DuPont Dimension and the Baxter Paramax.

On the accuracy of the Reflotron creatinine determination.

A study was undertaken to evaluate the accuracy of the Reflotron creatinine determination. Two aspects are reported: the calibration of the instrument and the influence of bilirubin on the test result. As the reference method, an HPLC based technique was used.

Assessment of a selected method for creatinine with special emphasis on bilirubin interference.

An HPLC-based method for the determination of creatinine was evaluated, with emphasis on interference by bilirubin. The method differed from other procedures, in that deproteinization was by ultrafiltration instead of precipitation with trichloroacetic acid. This allows a rapid, direct analysis by HPLC with very few experimental steps.

Renal stone analysis: LITHOS, an expert system for evaluation of X-ray diffractograms of urinary calculi.

An expert system for evaluation of X-ray diffraction patterns of urinary calculi is described and evaluated. The software was developed using the PERSONAL CONSULTANT expert system shell from Texas Instruments.

Spinal fluid protein revisited: a reappraisal of the biuret procedure.

In this study our previously described selected method, a biuret procedure with deproteinization, for the determination of spinal fluid protein is thoroughly discussed against the background of the results found with a number of Lowry modifications. The use of various separation techniques, i.e.