Expression of purinergic P2X7 receptors in subpopulations of peripheral blood mononuclear cells in early-stage of chronic kidney disease.

Chronic kidney disease (CKD) is known as a state of chronic low-grade inflammation, enhancing cardiovascular risk and immunodeficiency. Purinergic signaling has been accepted as a crucial component in the pathogenesis of various diseases, mediating a vast array of biological processes. The P2X7 receptor is one of the important cell surface regulators of several key inflammatory molecules. The aim of the study was to examine the expression of surface P2X7 receptors in subpopulations of peripheral blood mononuclear cells (PBMCs), and to evaluate the promising prognostic markers of inflammation (neutrophil/lymphocyte, Ne/Ly ratio) and cardiovascular risk (monocyte/high density lipoprotein cholesterol, Mo/HDL ratio) in early-stage CKD. The study involved 15 healthy volunteers and 15 non-diabetic patients with CKD stage 2 - 3. PBMCs were isolated from heparinized blood by Ficoll gradient centrifugation. To determine the expression of P2X7 receptors in different subpopulations (CD14+ monocytes, CD3+ T-lymphocytes and CD19+ B-lymphocytes), the cells were stained with FITC-conjugated anti-P2X7. The monocyte, lymphocyte and neutrophil counts were measured in whole blood as a part of routine hemogram. The number of T- and B-lymphocytes was determined by flow cytometry using antibodies anti-CD3-PE and anti-CD19-PE, respectively. The expression of surface P2X7 receptors was 1.4 fold increased in PBMCs of CKD patients compared to healthy volunteers. The expression of P2X7 receptors was 2.1 fold higher in monocytes and 1.5 fold higher in the whole lymphocyte population, with significant increase only in B-cells. The monocyte count, as well as the Ne/Ly and Mo/HDL ratios were also significantly increased. In conclusion, the increased P2X7 receptors expression in monocytes, the monocyte count and the Ne/Ly ratio are manifestations of chronic inflammation already in early stages of CKD. The study also supports recent findings that the Mo/HDL ratio could be used as additional parameter for monitoring cardiovascular risk profile in these patients.

Fluorescence analysis of urine and its potential for ovarian cancer screening.

Early diagnosis of ovarian cancer could lead to decreased mortality. We assessed the possible use of urine autofluorescence analysis in its diagnostics and screening.We analysed urine from 42 healthy volunteers, 35 patients with benign, and 36 patients with malignant ovarian tumors. Synchronous fluorescence spectra with a 70 nm wavelength difference were recorded for (1:1 - 1:1024) urine dilutions. Concentration matrices of synchronous spectra (CMSS) were used to classify samples into tested groups.CMSS analysis allowed us to distinguish patients with malignant tumors from healthy ones with a high sensitivity (91.67 %) and specificity (100 %), a positive predictive value (PPV) 100 % and a negative predictive value (NPV) 93.33 %. However, discrimination between benign and malignant ovarian tumors was weaker, with sensitivity 86.11 %, specificity 77.14 %, PPV 79.49 % and NPV 84.38 %. Fluorescence intensity and the position of peaks at 330 and 360 nm were found to be associated with the grade and stage, suggesting that different fluorescent metabolites may prevail at different stages of the disease.CMSS analysis of urine provides an alternative for ovarian cancer screening method development and could be used as a diagnostic test to detect the recurrence of the disease after therapy.

The effect of vitamin D3 supplementation on intracellular calcium and plasma membrane calcium ATPase activity in early stages of chronic kidney disease.

Chronic kidney disease (CKD) is associated with increased concentration of intracellular calcium, which is pathological and may lead to irreversible damage of cell functions and structures. The aim of our study was to investigate the impact of 6 months vitamin D(3) supplementation (14 000 IU/week) on free cytosolic calcium concentration ([Ca(2+)](i)) and on the plasma membrane calcium ATPase (PMCA) activity of patients with CKD stage 2-3. PMCA activity of patients was also compared to that of healthy volunteers. Vitamin D(3) supplementation of CKD patients resulted in the decrease of [Ca(2+)](i) (119.79+/-5.87 nmol/l vs. 105.36+/-3.59 nmol/l, n=14, P<0.001), whereas PMCA activity of CKD patients (38.75+/-22.89 nmol P(i)/mg/h) remained unchanged after vitamin D(3) supplementation (40.96+/-17.74 nmol P(i)/mg/h, n=14). PMCA activity of early stage CKD patients before supplementation of vitamin D(3), was reduced by 34 % (42.01+/-20.64 nmol P(i)/mg/h) in comparison to healthy volunteers (63.68+/-20.32 nmol P(i)/mg/h, n=28, P<0.001). These results indicate that vitamin D(3) supplementation had a lowering effect on [Ca(2+)](i) and negligible effect on PMCA activity in CKD patients.

Fluorescence characteristics of human urine from normal individuals and ovarian cancer patients.

Early diagnostics of ovarian cancer is difficult, because there are no symptoms until the disease has progressed to an advanced stage. As urine contains many intrinsic fluorophores, modern fluorescence techniques are perspective candidates for new routine urine tests. The presented work deals with differences in the fluorescence of metabolites in urine of ovarian cancer patients comparing to healthy volunteers using the fluorescence excitation-emission matrices. The most serious differences were found in undiluted urine at the fluorescence emission wavelengths from 400 nm to 460 nm when excited at 310 - 390 nm. Statistical analyses of our data have shown a 5-fold reduction in the intensity of the peak at 330/420 nm (excitation/emission wavelength) for undiluted urine samples excreted by cancer patients as compared to those of normal donors. Moreover, the ratio of intensities of the peaks at 370/440 nm and at 330/420 nm is 18-times elevated in urine excreted by patients with ovarian cancer as compared to healthy urine samples. The observed changes could be interpreted as reduction of the presence of pyridoxic acid, whereas blue-fluorescing pteridines becomes dominant in excitation-emission matrices of cancer urine samples in comparison to healthy donors. We suggest pteridines, which are related to cellular metabolism, as suitable candidates for neoplasia-associated fluorescent markers in human urine. Our work showed that monitoring of human urine fluorescent metabolites offers an alternative for ovarian cancer screening.

[Chronic kidney disease and cellular calcium homeostasis]. / Chronické ochorenie obliciek a vápniková homeostáza bunky.

Free intracellular calcium represents a critical signaling mediator in a number of biological systems. Calcium cations (Ca2+) are an important ubiquitous messenger, controlling a broad range of cellular processes. Free cytosolic calcium concentration ([Ca2+]i) is controlled by mechanisms that regulate Ca2+ entry from the extracellular space and Ca2+ release from intracellular stores, and by the activity of ATP-dependent Ca2+ pumps and antiporters that move Ca2+ back into stores or out of cells. Chronic kidney disease is associated with a significant elevation in [Ca2+]i which is toxic to the cells and may be responsible for a multiple organ dysfunction. Disturbances in cellular calcium homeostasis in patients with chronic kidney disease represent a complex process. Our studies elucidate pathophysiological mechanisms of altered cellular calcium homeostasis in the peripheral blood mononuclear cells which represent the model of nonexcitable cells in patients with chronic kidney disease. The results demonstrate that [Ca2+]i is significantly increased in peripheral blood mononuclear cells already in early stages of chronic kidney disease. The calcium concentration of intracellular stores and the capacitative calcium entry into the cells of these patients are significantly higher in comparison with healthy volunteers. Also the pore-forming P2X7 receptors participate in increased [Ca2+]i in peripheral blood mononuclear cells of patients with chronic kidney disease. An altered P2X7 receptor function and increased P2X7 receptor expression may contribute to the complex disturbances in intracellular calcium homeostasis in chronic kidney disease. On the other hand, the activity of plasmatic membrane Ca2+-ATPases which is responsible for removing excessive calcium out of the cell, was found to be decreased by 25 % when compared to healthy subjects. It means that not only the mechanisms of entry, but also of the removal are impaired by the disease. All these alterations in calcium signaling are contributing very likely to the elevated [Ca2+]i from early stages of chronic kidney disease.

Effects of chronic kidney disease on blood cells membrane properties.

Chronic kidney disease (CKD) is progressive loss of renal function associated among others with increased intracellular calcium concentration. The purpose of this study was to identify the effects of CKD on cell membrane properties such as human red blood cell Ca(2+) ATPase activity, lymphocyte plasma membrane P2X(7) receptor expression and function. This could help us in elucidating the origin of increased calcium concentration in blood cells. We found out Ca(2+) ATPase activity is decreased in early stage CKD patients resulting in altered calcium removal from cytoplasm. By means of flow cytometry we assessed that P2X(7) receptor expression on lymphocyte membrane is 1.5 fold increased for CKD patients. Moreover, we detected an increased uptake of ethidium bromide through this receptor in CKD at basal conditions. It means CKD lymphocyte membranes contain more receptors which are more permeable thus allowing increased calcium influx from extracellular milieu. Finally, we can state alterations in blood cell membranes are closely linked to CKD and may be responsible for intracellular calcium accumulation.

Enalapril inhibits growth and proliferation of various tissues in rat normotensive four-sixths kidney ablation nephropathy.

Most experimental studies on kidney proliferation and its attenuation by angiotensin-converting enzyme inhibitors were performed in the rat hypertensive remnant-kidney model with a five-sixths kidney ablation. The developing hypertension rose the objections on the hypertension and its treatment in control rats. A normotensive four-sixths remnant-kidney model (Nx) was elaborated, compared with sham-operated (S) animals, and a subantihypertensive dosage of enalapril (E) was administered for 4 weeks of intensive kidney tissue proliferation (NxE). The pair-fed groups increased their body weight and blood pressure comparably. Moderately increased plasma creatinine and urea concentrations were found in the Nx group; markedly increased levels in the NxE group. Nx increased proteinuria, and E attenuated its increase. The remnant-kidney weight (Nx 912+/-31 vs. S 1,111+/-36 mg, p<0.001) was still lower, but collagen (Col; Nx 164+/-2 vs. S 148+/-5 mg/100 g, p<0.05) and tubular protein/DNA ratio (Nx 26.2+/-10.8 vs. S 9.8+/-1. 0, p<0.05) increased markedly in the Nx group; E attenuated the kidney growth (NxE 719+/-31 vs. Nx 912+/-31 mg, p<0.01) and decreased the tubular protein/DNA ratio remarkably (NxE 15.3+/-10.5 vs. Nx 26.2 +/-10.8), but E did not inhibit the Col accumulation. Nx decreased the heart (Nx 1,002+/-28 vs. S 1,130+/-41 mg, p<0.05), but not liver weights and did not influence Col concentrations or protein/DNA ratios either in heart or liver. E potentiated the weight decrease of heart (NxE 862+/-20 vs. Nx 1,002+/-28 mg, p<0.01) and liver (NxE 8.3+/-0.44 vs. Nx 10.3+/-0.51 g, p<0.001) and Col accumulation (heart: NxE 113+/-6 vs. Nx 92+/-5 mg/100 g, p<0.01; liver: NxE 134+/-8 vs. Nx 101+/-9 mg/100 g, p<0.01). Nx did not influence either the soleus muscle weight or its Col accumulation, but it increased its protein/DNA ratio (Nx 66.3+/-4.7 vs. S 35.5+/-2. 8 mg/100 g, p<0.01). E increased the Col concentration in muscle (NxE 141+/-3 vs. Nx 110+/-5 mg/100 g, p<0.01), while it attenuated the increase in protein/DNA ratio (NxE 36.6+/-2.1 vs. Nx 66.3+/-4.7, p<0.01). In conclusion, kidney ablation nephropathy stimulating kidney proliferation evokes only minor changes in heart, liver and striated muscle. E inhibits markedly the kidney proliferation and functional recovery, but does not prevent the Col accumulation. E evokes antiproliferative changes also in the heart and surprisingly even in the liver. Alterations in soleus muscle are only borderline.

Enalapril in subantihypertensive dosage attenuates kidney proliferation and functional recovery in normotensive ablation nephropathy of the rat.

Most studies on the antiproliferative action of angiotensin converting enzyme inhibitors (ACEI) were performed in a rat hypertensive remnant kidney model with 5/6 kidney ablation which raised objections about the antihypertensive effect of ACEI and the influence of other antihypertensive drugs administered to remnant kidney control rats. To prevent these objections, a normotensive 4/6 remnant kidney model was elaborated and a subantihypertensive dosage of enalapril was used to evaluate its antiproliferative action. Subtotally nephrectomized rats (Nx) markedly increased the remnant kidney weight during a 4-week period and this rise was prevented by the treatment with enalapril (NxE) (Nx +297+/-35 mg vs. sham-operated +145+/-32 mg, p<0.001; NxE +154+/-35 mg vs. Nx p<0.001). While collagen concentration in the kidney cortex was not increased in sham-operated rats (Sham) in comparison with the control group (Ctrl) at the beginning of the study, the subsequent increase was significant in the Nx group and enalapril did not attenuate this increase (Sham 148+/-5 mg/100 g w.w. vs. Nx 164+/-2 mg/100 g w.w., p<0.01; NxE 161+/-4 mg/100 g w.w. vs. Sham p<0.05). The tubular protein/DNA ratio increase, which was significant in the Nx group, was inhibited by enalapril (Nx 26.2+/-10.5 vs. NxE 15.3+/-2.6, p<0.05). The protein/DNA ratio was much lower in glomeruli, with no significant changes in either the Nx or NxE groups. Serum urea concentrations were slightly higher in the Nx group than in the sham-operated group, but markedly elevated in the NxE group (Nx 10.71+/-0.76 mmol/l vs. Sham 6.10+/-0.33 mmol/l, p<0.001; NxE 28.9+/-2.6 mmol/l vs. Sham p<0.001). Creatinine concentrations in the Nx group were increased in comparison with the sham-operated group and markedly increased in the NxE group (Nx 63.7+/-3.56 micromol/l vs. Sham 37.2+/-2.84 micromol/l, p<0.001; NxE 107.0+/-5.2 micromol/l vs. Sham p<0.001). The clearance of creatinine was lower in the Nx group than in the sham-operated group and was markedly reduced in the NxE group (Nx 0.89+/-0.06 ml/min.g kidney wt. vs. Sham 1.05+/-0.16 ml/min x g kidney wt., p<0.01; NxE 0.58+/-0.029 ml/min x g kidney wt. vs. Sham, p<0.001). Enalapril improved proteinuria in comparison with the Nx group (NxE 5.6+/-0.6 mg/24 h vs. Nx 16.1+/-3.4 mg/24 h, p<0.05). Thus remnant kidney proliferation is substantial even in normotensive rats. It includes both proliferation and collagen accumulation with partial recovery of kidney weight and function, but is accompanied by enhanced proteinuria. Enalapril attenuates the proliferation and decreases proteinuria but prolongs kidney function recovery.

Inhibition of glucose utilization in isolated rat soleus muscle by pseudouridine: implications for renal failure.

Pseudouridine (psi) is an outstanding nucleoside which is not rebuilt into the tRNA once the parent tRNA is broken down. psi inhibits basal glucose utilization in isolated rat soleus muscle with intact membrane with AD(50)42 mumol/l and Cmax 66%. Psi at concentrations found in renal failure patients inhibits both the insulin- and tolbutamide-stimulated glucose utilization. Its inhibitory activity is partially additive with diltiazem inhibition and nonadditive in the case of magnesium depletion. It is concluded that psi inhibits glucose utilization at the level of Ca modulation in the insulin regulatory cascade.

Pseudouridine excretion in healthy subjects and its accumulation in renal failure.

Pseudouridine (psi) is a unique nucleoside accumulated in the sera of renal failure (RF) patients. Surprisingly data on its excretion are lacking. To get an overview, the psi serum level and urinary excretion were investigated in 73 healthy subjects (C), 16 patients not on dialysis (ND) and 12 hemodialysis patients (D). It was found: (a) psi accumulates in the sera of both ND and D patients. An inverse power correlation fits best with the relationship between serum psi and the clearance of endogenous creatinine (CCr). The amount of psi filtered in glomeruli of ND patients increases while it remains practically unchanged in D patients. However, the psi filtration load of residual nephrons increases with the decreasing CCr as a consequence of its increased serum concentration. (b) Both psi net resorption and secretion have been found in C subjects. The increased psi resorption diminishes the necessary increase of psi urinary excretion both in ND and D patients. The increase of psi resorption is marked if calculated on residual nephrons. (c) The slightly decreased psi excretion excludes the participation of its increased synthesis in its accumulation in RF. It is concluded that psi accumulation in RF is caused by the impairment of its kidney excretion and the increased psi resorption participates markedly in its retention.