The results of external quality assessment programme on urine leukocyte and erythrocyte counting in Poland

Introduction

Urine particle analysis is an important diagnostic tool. The aim of this study was to evaluate the quality of urine leukocyte (WBC) and erythrocyte (RBC) counting results obtained with manual and automated methods in Polish laboratories participating in the international external quality assessment (EQA) programme.

Materials and methods

1400 WBC and RBC counting results were obtained from 183 laboratories in EQA surveys organised by Labquality (Helsinki, Finland) from 2017 to 2019. The between-laboratory coefficient of variation (CV), the percentage difference between the laboratories' results and target values (Q-score (%)), as well as modified Youden plots were analysed.

Results

For automated method groups, the medians of inter-laboratory CVs varied from 14% to 33% for WBC counting and from 10% to 39% for RBC counting. For manual method groups, the medians of CV varied from 53% to 71% (WBC) and from 55% to 70% (RBC), and they were significantly higher, in comparison to CVs for most automated method groups (P < 0.001). The highest percentage of results outside the target limits (36%) and the highest range of Q-score (%) (from - 93% to 706%) were observed for laboratories which participated in the surveys for the first or second time. The percentage of deviating results and the ranges of Q-score decreased with an increased frequency of laboratories’ participation in the surveys.

Conclusions

The quality of manual methods of urine WBC and RBC counting is unsatisfactory. There is an urgent need to take actions to improve laboratories’ performance and to increase harmonisation of the results.

Non-HDL-C/TG ratio indicates significant underestimation of calculated low-density lipoprotein cholesterol (LDL-C) better than TG level: a study on the reliability of mathematical formulas used for LDL-C estimation

OBJECTIVES

Low-density lipoprotein cholesterol (LDL-C) is the main laboratory parameter used for the management of cardiovascular disease. The aim of this study was to compare measured LDL-C with LDL-C as calculated by the Friedewald, Martin/Hopkins, Vujovic, and Sampson formulas with regard to triglyceride (TG), LDL-C and non-high-density lipoprotein cholesterol (non-HDL-C)/TG ratio.

METHODS

The 1,209 calculated LDL-C results were compared with LDL-C measured using ultracentrifugation-precipitation (first study) and direct (second study) methods. The Passing-Bablok regression was applied to compare the methods. The percentage difference between calculated and measured LDL-C (total error) and the number of results exceeding the total error goal of 12% were established.

RESULTS

There was good correlation between the measurement and calculation methods (r 0.962-0.985). The median total error ranged from -2.7%/+1.4% (first/second study) for Vujovic formula to -6.7%/-4.3% for Friedewald formula. The numbers of underestimated results exceeding the total error goal of 12% were 67 (Vujovic), 134 (Martin/Hopkins), 157 (Samspon), and 239 (Friedewald). Less than 7% of those results were obtained for samples with TG >4.5 mmol/L. From 57% (Martin/Hopkins) to 81% (Vujovic) of underestimated results were obtained for samples with a non-HDL-C/TG ratio of <2.4.

CONCLUSIONS

The Martin/Hopkins, Vujovic and Sampson formulas appear to be more accurate than the Friedewald formula. To minimize the number of significantly underestimated LDL-C results, we propose the implementation of risk categories according to non-HDL-C/TG ratio and suggest that for samples with a non-HDL-C/TG ratio of <1.2, the LDL-C level should not be calculated but measured independently from TG level.

The effect of Cistus incanus herbal tea supplementation on oxidative stress markers and lipid profile in healthy adults

BACKGROUND

Oxidative stress and dyslipidemia play a critical role in the development of cardiovascular disease (CVD). Regular intake of polyphenol-rich diets is associated with a reduced risk of CVDs.

METHODS

The present study was a pilot study with 24 healthy volunteers and was designed to determine if a 12-week administration of Cistus incanus herbal tea, containing phenolic acids and flavonoids, reduces cardiovascular risk factors including oxidative stress and dyslipidemia in healthy adults. Phenolic compounds profile and antibacterial activity of Cistus incanus infusion were also measured.

RESULTS

Herbal infusion led to improvement in lipid profile by increase (D4%, p = 0.033) high-density lipoprotein cholesterol concentration and decrease triglyceride (D14%, p = 0.013) concentrations. In addition, the Cistus incanus diet was associated with decreased serum concentrations of malondialdehyde (D16%, p < 0.01) and advanced oxidation protein products (D18%, p < 0.001).

CONCLUSIONS

Cistus incanus administration decreases cardiovascular risk factors including oxidative stress and dyslipidemia and this action supports the idea of using Cistus incanus tea on a daily basis as an effective dietary component for prevention of atherosclerotic CVD.

Apolipoprotein E gene polymorphism and renal function are associated with apolipoprotein E concentration in patients with chronic kidney disease

Background

Chronic kidney disease (CKD) associates with complex lipoprotein disturbances resulting in high cardiovascular risk. Apolipoprotein E (APOE) is a polymorphic protein with three common isoforms (E2; E3; E4) that plays a crucial role in lipoprotein metabolism, including hepatic clearance of chylomicrons and very low-density lipoprotein (VLDL) remnants, and reverse cholesterol transport. It demonstrates anti-atherogenic properties but data concerning the link between polymorphism and level of APOE in CKD patients are inconclusive.

The aim of our research was to assess the relationship between APOE gene polymorphism and APOE concentration and its redistribution among lipoproteins along with CKD progression.

Methods

90 non-dialysed CKD patients were included into the study. Real time PCR was used for APOE genotyping. APOE level was measured in serum and in isolated lipoprotein fractions (VLDL; IDL + HDL; HDL). Kidney function was assessed using eGFR CKD-EPI formula.

Results

The population was divided into three APOE genotype subgroups: E2(ε2ε3), E3(ε3ε3) and E4(ε3ε4). The highest APOE level was observed for the E2 subgroup (p < 0.001). APOE concentration positively correlated with eGFR value in the E2 subgroup (r = 0.7, p < 0.001) but inversely in the E3 subgroup (r = − 0.29, p = 0.02).). A lower concentration of APOE in the E2 subgroup was associated with its diminished contents in HDL and IDL + LDL particles. In the E3 subgroup, the higher concentration of APOE was related to the increased number of non-HDL lipoproteins.

Conclusion

In patients with CKD, APOE genotype as well as renal function are associated with the concentration of APOE and its redistribution among lipoprotein classes.

Progression of Chronic Kidney Disease Affects HDL Impact on Lipoprotein Lipase (LPL)-Mediated VLDL Lipolysis Efficiency

BACKGROUND/AIMS

Hypertriglyceridaemia (HTG) and reduction and dysfunction of high density lipoprotein (HDL) are common lipid disturbances in chronic kidney disease (CKD). HTG in CKD is caused mainly by the decreased efficiency of lipoprotein lipase (LPL)-mediated very low density lipoprotein triglyceride (VLDL-TG) lipolysis. It has not been clarified whether HDL dysfunction in CKD contributes directly to HTG development; thus, the aim of this study was to assess the impact of CKD progression on the ability of HDL to enhance LPL-mediated VLDL-TG lipolysis efficiency.

METHODS

VLDL was isolated from non-dialysis patients in CKD stages 3 and 4 and from non-CKD patients. The VLDL was incubated with LPL at the constant LPL:VLDL-TG ratio, in the absence or presence of HDL. After incubation, the VLDL was separated and the percentage (%) of hydrolyzed TG was calculated.

RESULTS

HDL presence increased the lipolysis efficiency of VLDL isolated from CKD and non-CKD patients, for the VLDL-TG> 50 mg/dl. Its effect was dependent on the VLDL-TG and HDL-cholesterol concentrations in the reaction mixtures: the higher the concentrations of VLDL-TG and HDL-cholesterol, the greater the effect. The positive impact of HDL on VLDL lipolysis was modified by CKD progression: the percentage of lipolyzed VLDL-TG in the presence of HDL decreased with a reduction in eGFR (r=0.43, p=0.009), and for patients with stage 4 CKD, no positive impact of HDL on lipolysis was observed. The percentage of lipolyzed TG correlated negatively with apoE and apoCs content in VLDL, and positively with HDL-apoCII, as well as with VLDL and HDL apoCII/ apoCIII ratios. The progression of CKD was associated with unfavourable changes in VLDL and HDL composition; apoE and apoCs levels increased in VLDL with a decrease in eGFR whereas the HDL-cholesterol level decreased.

CONCLUSION

The progression of CKD affects lipoprotein composition and properties, and modulates the positive impact of HDL on VLDL lipolysis efficiency. In CKD patients, HDL deficiency and dysfunction can directly affect hypertriglyceridaemia development.

Impact of plant-based diet on lipid risk factors for atherosclerosis

BACKGROUND

The aim of the study was to investigate the effect of a vegan diet on the serum lipid profile with particular regard to the parameters characterizing the high-density lipoprotein (HDL) fractions in subjects without subclinical atherosclerosis, measured by carotid Doppler ultrasonography.

METHODS AND RESULTS

Forty-two 23 to 38 year old subjects (21 omnivores and 21 vegans) participated in the study. Compared to the omnivores, the vegan subjects were characterized by lower parameters of lipid profile: total cholesterol (p < 0.001), low-density lipoprotein (LDL)-cholesterol (p < 0.001), non-HDL-cholesterol (p < 0.001), apolipoprotein B (apoB) (p < 0.001) and phospholipids (p < 0.01). Concentration of HDL-cholesterol was apparently similar between groups. Furthermore, the parameters which characterize HDL particles (con-centration of apolipoproteins AI [apoAI] and AII, HDL-phospholipids, LpAI fraction and pre-b1-HDL fraction) were not significantly different between omnivore and vegan subjects. The apoB/apoAI ratio in vegans was lower than in omnivores (p < 0.01). There was no difference between serum concentration of triacylglycerols between omnivores and vegans. The activity of paraoxonase-1 and 8-iso-prostaglandin F2a concentration were also not different between the study groups.

CONCLUSIONS

We suggest that a vegan diet may have a beneficial effect on serum lipid profile and cardiovascular protection, but it is not associated with changes in HDL composition.

[ApoE-containing HDL and the development of atherosclerosis]

The current state of knowledge about the role of high density lipoproteins (HDL) indicates that their anti-atherogenic function is mainly related to the effectiveness of their actions (mostly to the participation in reverse cholesterol transport from tissues to liver) rather than the concentration of HDL itself. HDLs are highly heterogeneous in their structure, lipid and protein composition and metabolic pathways and individual HDL subpopulations differ in their biological activity and effectiveness of anti-atherogenic actions. Apolipoproteins play a key role in HDL metabolism, therefore their presence in lipoproteins is one of the main criterion for HDL classification. According to this criterion HDLs containing apolipoprotein E, called HDL-apoE, are distinguished. Although the anti-atherogenic role of apo E has been demonstrated in many scientific reports, understanding of the mechanisms of formation, transformation and the role of HDL-apoE is still the aim of intense research. The results of epidemiological studies are inconclusive; some of them have demonstrated that high HDL- -apoE concentration has been associated with lower risk of developing coronary heart disease (CHD), while other studies have shown that high levels of HDL-apoE has been an independent risk factor for cardiovascular events and positively correlated with other risk factors for CHD.

Interaction between VLDL and phosphatidylcholine liposomes generates new γ-LpE-like particles

One of the subfractions of HDL involved in reverse cholesterol transport is γ-LpE. It has been assumed that, like preβ-LpAI, it can be generated during the interaction between phosphatidylcholine liposomes and lipoproteins and can contribute to more efficient cholesterol efflux after the introduction of liposomes to plasma. However, there has been no evidence concerning what the sources of these particles in plasma might be. Here, we determined whether the interaction of phosphatidylcholine liposomes with VLDL and the subsequent conversions of particles could be a source of new γ-LpE particles. We found that the interaction between liposomes and VLDL affected its lipid and protein composition. The content of phospholipids increased (~96 %) while the content of free cholesterol and apolipoprotein E decreased in VLDL during the reaction with liposomes (~100 and ~24 %, respectively). New particles which did not contain apolipoprotein B were generated. Heterogeneous HDL-sized populations of particles were generated, containing phospholipids and apolipoprotein E as the sole apolipoprotein, with densities from 1.063 to 1.21 g/ml, either with γ-mobility on agarose gel and Stokes diameters from 8.58 to 22.07 nm or with preβ-mobility and Stokes diameters from 9.9 to 21.08 nm. The obtained results contribute to the understanding of changes in lipoproteins under the influence of phosphatidylcholine liposomes, showing the formation of new (γ-LpE)-like and (preβ-LpE)-like particles, similar in mobility and size to plasma HDL-LpE. These newly generated particles can claim a share of the antiatherogenic effects of liposomes, observed in studies both in vitro and in vivo.

Estimation of oxidative stress markers in chronic kidney disease

Changes mediated by oxidative stress are thought to be involved with atherosclerosis in patients with chronic kidney disease (CKD). The purpose of this study was to analyze the markers of oxidative damage and the activity of antioxidative enzymes as well as the total antioxidant capability in patients with different stages of CKD, both conventionally treated and dialyzed. We evaluated the oxidative modification of lipids (by oxidized low-density lipoprotein and malonodialdehyde levels) and proteins (by advanced oxidation protein products level). We also assessed the activity of paraoxonase-1 and glutathione peroxidases and total antioxidant status. Compared with the control group, the uremic patients, both dialyzed and nondialyzed, had higher levels of all studied plasma oxidative stress markers and decreased activity of antioxidative enzymes. Our results lead us to conclude that oxidative stress seems to be related rather to the uremic state than to the dialysis treatment. We also showed that estimating total antioxidant status in a simple test is unreliable for assessing the antioxidant ability of patients with CKD.

[Disturbances of lipoprotein metabolism in metabolic syndrome]

Dyslipidemia in metabolic syndrome (MS), called the atherogenic triad, includes elevated levels of plasma triglycerides (TGs), low levels of HDL-cholesterol (HDL-CH), and the presence of small dense low-density lipoproteins (sdLDLs) with normal or slightly elevated LDL-CH levels. Insulin resistance drives the increase in the three main sources of TG for VLDL synthesis: fatty-acid flux from adipose tissue, de novo lipogenesis, and uptake of remnant lipoproteins. Overproduction of VLDL, predominantly triglyceride-rich large VLDL1 particles, induces the cascade of events which lead to abnormalities of other plasma lipoproteins. The accumulation of VLDL in plasma and decreased activity of lipoprotein lipase (LPL) impair the catabolism of chylomicrons. Moreover, hyperinsulinemia induces increased intestinal production of chylomicrons. These factors cause augmented postprandial lipemia. Hepatic overproduction of VLDL leads to an increased level of VLDL remnants in plasma. Highly atherogenic sdLDLs are generated from VLDL1 particles by the action of LPL, cholesterol ester transfer protein (CETP), and hepatic lipase (HL). In the presence of hypertriglyceridemia, accelerated CETP-mediated lipid transfer generates TG-enriched HDL particles. This enhances HDL catabolism mediated by HL and endothelial lipase (EL). The assessment of risk of atherosclerotic cardiovascular disease in MS related to low HDL-CH and the presence of sdLDL particles may be improved by the incorporation of measurements of apolipoproteins (apo)-B and apoA-I into clinical practice. In addition, the concentration of non-HDL-CH may be useful in quantifying apo-B-containing atherogenic lipoproteins.

Phospholipids mediated conversion of HDLs generates specific apoA-II pre-beta mobility particles

Apolipoproteins (apo)A-I and A-II are major proteins of human HDL. The cycling of apoA-I between lipid-poor and lipid-rich forms of HDL plays a key role in the transport of cholesterol by these particles. ApoA-II resides only in part of HDL particles, and little is known about its role in HDL metabolism. Our study investigates the redistribution of apoA-II after HDL remodelling induced by exogenous phospholipids (PL). During incubation with egg yolk lecithin (EYL) liposomes, human HDL became PL-enriched and free cholesterol (FC)-depleted, and lost small amounts of apoA-I and apoA-II. The loss of FC and apolipoproteins correlated with the rise of PL content in HDL. Agarose gel electrophoresis demonstrated the appearance of new pre-beta mobility fractions containing apoA-I and apoA-II in liposomes and HDL mixtures. Two-dimensional nondenaturing 2-27% PAGE has shown that the pre-beta mobility fraction that appeared at initial liposome-PL/HDL-PL ratio 5:1 consisted of two distinct heterogeneous subpopulations of particles containing either apoA-I or apoA-II. Our study provides evidence that during HDL conversion mediated by PL apoA-II dissociated from HDL particles yielding apoA-II-specific pre-beta mobility particles. This observation supports the hypothesis that apoA-II in plasma, like apoA-I, may cycle between lipid-poor and lipid-rich forms of HDL.