vs. 19.31 (7.4) g/L for other patients; P=0.1]. Notably, HCV-coinfected patients had higher (P=0.03) plasma γ-globulin concentrations [20.99 (7.9) g/L] than patients who were not coinfected [16.84 (4.5) g/L]. However, we did not detect any relationship between HCV coinfection and changes in the overall lipoprotein profile. To assess the clinical significance of these discrepancies among methods, HDL cholesterol values (obtained using the homogeneous method or ultracentrifugation) were used to assign HIV-infected patients as having low or high HDL cholesterol concentrations. For this purpose, we applied the Framingham risk scored based on the Adult Treatment Panel III (ATP III) classification of HDL cholesterol . As shown in Figure 1c, the total percentage of misclassifications was 11.4%. We found that the HDL cholesterol values for stored samples were significantly lower than find more Selleck HDAC inhibitor the baseline measurements [at baseline: 1.14 (0.4) mmol/L; storage at −80 °C for 1 year: 1.05 (0.4) mmol/L; P<0.001 vs. baseline; storage at 4 °C for 1 week: 1.02 (0.4) mmol/L; P<0.001 vs. baseline]. As shown in Figure 1d, the effect of storage regimen on HDL cholesterol concentration was more pronounced in HIV-infected patients than in control subjects. Most samples from HIV-infected patients showed lower
HDL cholesterol values compared with baseline, but in healthy subjects lower values were only found for 35% of the samples. Adenosine triphosphate However, other changes in particle composition were unlikely because an effect of storage was not found when the apoA-I concentration was measured (Fig. 1e), indicating that apoA-I is less influenced by the storage conditions.
Among the variables studied, none showed a significant impact in control samples, but in samples from HIV-infected patients we found a positive and significant correlation between the decrease of HDL cholesterol values and plasma γ-globulin concentrations in both storage regimens (at 4 °C for 1 week: y=0.01x+0.05; r=0.37, P<0.003; at −80 °C for 1 year: y=0.003x+0.07; r=0.25, P<0.05). This was further confirmed with multivariate analyses either in samples stored at 4 °C [B=0.008 (−0.004 to 0.012); P<0.001] or in samples stored at −80 °C [B=0.006 (0.002–0.010); P=0.004]. However, as illustrated in Figure 1f, we did not observe a significant impact of plasma γ-globulin concentration on apoA-I determination. Moreover, the formula resulting from the application of linear regression analysis, with apoA-I and γ-globulin concentrations included in the model, was HDL cholesterol=−0.85+[1.2 × apoA-I (g/L)]+[0.011 ×γ-globulin (g/L)], and this predicts 80% of the variance in the true HDL cholesterol values (ultracentrifugation). The inverse association between HDL cholesterol concentration and the risk of coronary disease has been established in epidemiological studies .