Improvement in dyslipidaemia after switching stavudine to tenofovir and replacing protease inhibitors with efavirenz in HIV-infected children.

OBJECTIVE: To assess the impact on immunological, virological and metabolic parameters of replacing protease inhibitors (PIs) with efavirenz and replacing stavudine with tenofovir in HIV-infected children. METHODS: A 48-week prospective evaluation of 28 HIV-infected children, with stable undetectable HIV-1 loads, who were taking highly active antiretroviral therapy (HAART) containing lamivudine, stavudine and a PI. Individuals were randomized to switch PI to efavirenz and stavudine to tenofovir at baseline (Group 1) or at week 24 (Group 2). Patient assessment included: clinical evaluation, viral load, CD4+ T-cell count, fasting blood levels and urine samples. RESULTS: All individuals maintained HIV RNA <50 copies/ml and unchanged CD4+ T-cell count through week 48. In Group 1 individuals, a significant decrease in cholesterol (P < 0.05), cholesterol:high-density lipoprotein (HDL) ratio (P < 0.01) and triglycerides (P < 0.05) was observed 24 and 48 weeks after the switch of HAART. The percentage of Group 1 children with increased cholesterol and triglycerides markedly decreased over the study period (from 43% to 0% and from 36% to 7%, respectively). In Group 2 individuals, unchanged lipids in the 24 weeks prior to the switch of HAART and a significant improvement on cholesterol (P < 0.05), cholesterol:HDL ratio (P < 0.01) and triglycerides (P < 0.05) were observed 24 weeks after the switch of HAART. The percentage of Group 2 children with increased cholesterol and triglycerides markedly decreased 24 weeks after the switch of HAART (from 46% to 7% and from 54% to 0%, respectively). Proteinuria and glucosuria were not detected in any individual. The mean values of serum creatinine, serum phosphorus, serum bicarbonate, estimated glomerular filtration rate, urinary microalbumin/creatinine, alpha-1-microglobulin/creatinine ratio and maximal tubular phosphate reabsorption remained unchanged in both groups. CONCLUSIONS: In HIV-infected children, switching PI to efavirenz and stavudine to tenofovir is virologically and immunologically safe, is not associated with renal impairment and provides a significant improvement in lipid profile.

Analytical variation in the measurement of serum monoclonal component by capillary electrophoresis.

The amount of serum monoclonal components (MC), and moreover, their variation with time are important factors for differentiating malignancy-associated from benign gammopathies. Capillary electrophoresis (CE) of serum proteins allows better quantitative measurement in comparison to conventional gel-supported electrophoresis. We investigated the analytical variation of CE measurement of serum MC of different sizes: the variation due to integration settings and the analytical variation of the CE procedure were assessed in separate experiments. "Small" MC (in the interval 4-14% of total protein) were measured with analytical imprecision (CV%) in the interval 5-25%. The step of setting the integration limits was found to generate an important portion of such an overall variability. The imprecision was negatively, nonlinearly related to MC concentration: at the "critical" MC value of 40% of total protein, the analytical imprecision was CV approximately 2.5%. The variation computed from sets of subsequent routine MC measurements in "stable" patients with MGUS, over observation intervals from 10 to 30 months, behaved similarly to the "pure" analytical variation measured experimentally. This suggested very low, if any, biological variation of MC. Differences between subsequent MC measurements in a patient should be interpreted in light of the analytical variation.

Measurement of C-reactive protein: two high sensitivity methods compared.

C-reactive protein (CRP) is an acute phase marker and a predictor of the risk of developing atherosclerotic complications. However, as a predictor of this risk, high sensitivity measurements are needed, and high sensitive CRP (hsCRP) assays have been developed. In this study, we experimentally compared two hsCRP assays, based on nephelometry and turbidimetry, both implemented on automated analyzers. Linearity, imprecision, turbidity interference, and results in the assay of 96 samples have been compared. Method comparison of the same two analytical systems in the assay of CRP was also performed on the basis of results in an interlaboratory external quality assessment scheme (EQAS). The two systems were found to perform substantially equally, both in hsCRP and in CRP measurement, but in the hsCRP assay the precision of nephelometry (CV% in the interval 3.0-5.8) was lower than that of turbidimetry (CV% in the interval 1.8-2.3). The classification of results by the two methods into three predefined relative risk classes gave 18% rate of discordance, in any case by one class only. The two methods proved reliable and comparable in the measurement of hsCRP, but precision should be improved.

High-density lipoproteins contribute to the alpha-1-globulin zone in capillary electrophoresis of human serum proteins.

Alpha-1-antitrypsin (AAT) and alpha-1-acid glycoprotein (AAG) are reported to be the main proteins contributing to the alpha-1-globulin capillary zone electrophoresis (CZE) zone, but the sum (AAT + AAG) showed lower than the alpha-1-globulin. We investigated the role of high-density lipoprotein (HDL), an additional protein migrating in the alpha-1-globulin zone, as a possible cause for such a gap. In a set of 98 sera we measured the alpha-1-globulin with a dedicated clinical capillary electrophoresis system, and AAT, AAG and apolipoprotein A-1 (ApoA) by immunonephelometry. The alpha-1-globulin were consistently higher than the sum (AAT + AAG), by (mean value +/- standard deviation) 1.70 +/- 0.88 g/L in 49 sera with low ApoA, and by 3.59 +/- 0.75 g/L in 49 sera with high ApoA. Corresponding figures in the comparison alpha-1-globulin/(AAT + AAG + ApoA) were reduced to 1.08 +/- 0.77 g/L and 1.67 +/- 0.70 g/L. It is concluded that HDL significantly contribute to the CZE alpha-1-globulin zone, but do not completely explain the differences between the electrophoretic and the immunochemical measurements. However, CZE alpha-1-globulin measurements give information about increases of the two major acute phase proteins comparable to specific protein measurements.

Capillary zone electrophoresis of serum proteins: effects of changed analytical conditions.

Analytical conditions in a system for capillary zone electrophoresis (Beckman Paragon CZE 2000) were originally selected to allow serum protein separation into five discrete protein zones, corresponding to those of conventional clinical electrophoresis. To improve the system's performance, new analytical conditions have been made available. We compared the two sets of conditions ("new" = y; "old" = x) for possible variations of results caused by the change. One hundred thirteen serum samples, covering wide intervals of values, were assayed on two twin instruments working under the old and the new conditions; results were assessed statistically and graphically. Possible clinical significance of differences was checked by comparison with the biological variation-based quality specifications for bias. Statistically significant (y-x) differences were observed for the alpha1-, alpha2- and beta-globulin zones; clinically significant differences were observed for all the zones, with the exception of the gamma-globulin zone. Therefore, old/new regression equations were calculated, whose reliability was assured by the wide interval of values, by the large sample size, and by the low dispersion of single values around the mean concordance estimates. Such equations may be used to convert "old" into "new" reference values, and for the intercomparison of patient results obtained under different analytical conditions.

Precision and long-term stability of capillary electrophoresis measurement of serum protein zones.

BACKGROUND: Analytical evaluations of an available system for capillary zone electrophoresis (CZE) of serum protein have been reported. However, data concerning long-term precision and stability of the system, operated under routine conditions, are lacking. We report data from an internal quality control (QC) scheme, obtained over a 1-year period. METHODS: Measurements were done with a pair of instruments (Beckman Paragon CZE 2000 system), each equipped with seven capillaries. After preliminary (1 month) assessment of possible inter-capillary and inter-instrument variations, the QC material (a home prepared serum pool stored in the frozen state) was assayed daily over a 1-year period. RESULTS: Maximum inter-capillary and inter-instrument differences were 3.1% and 2.4%. No significant trend was observed for daily values (205 measurements over 1 year); in the same period overall imprecision values (CV) were in the interval 1.2% (albumin) to 3.2-6.1% (globulin zones). Mean monthly imprecision (CV) values were in the interval 1.1% (albumin) to 5.2% (globulin zones). There was no significant trend of monthly means with time. The observed imprecision values were within the biological variation-derived goals for imprecision. CONCLUSIONS: It is concluded that the assessed analytical instruments, operated in routine conditions, show long-term stability and imprecision consistent with the clinical use of the results produced.