Expression of heat shock proteins 47 and 70 in the peritoneum of patients on continuous ambulatory peritoneal dialysis

BACKGROUND: Peritoneal sclerosis, characterized by collagen accumulation, is a serious complication in continuous ambulatory peritoneal dialysis (CAPD) therapy. Heat shock protein 47 (HSP47) is a collagen-specific molecular chaperon and is closely associated with collagen synthesis. METHODS: We determined the expression of HSP47 and HSP70 (nonspecific for collagen synthesis) by immunohistochemistry in peritoneal tissues of patients on CAPD. The tissue for collagen III, alpha-smooth muscle actin (alpha-SMA), and CD68 (a marker for macrophages) were also stained. Thirty-two peritoneal samples were divided into three groups (group A1, 11 patients who had no ultrafiltration loss; group A2, 9 patients who had ultrafiltration loss; and group B, 12 specimens who had end-stage renal disease prior to induction of CAPD. RESULTS: In group B, staining for HSP47, HSP70, and collagen III in peritoneal tissues was faint, and only a few cells were positive for alpha-SMA and CD68. In contrast, HSP47, HSP70, and collagen III were expressed in areas of thickened connective tissues in fibrotic peritoneal specimens of CAPD patients. The expression level of HSP47, HSP70, collagen III, and alpha-SMA and the number of CD68-positive cells in group A2 were significantly higher than those in groups A1 and B. HSP47/HSP70-positive cells were mesothelial cells, adipocytes, and alpha-SMA-positive myofibroblasts. Furthermore, the expression level of HSP47 was significantly higher in peritoneal specimens from patients with refractory peritonitis than without it and was significantly higher in patients with more than 60 months of CAPD therapy than that in patients with less than 60 months of CAPD. CONCLUSION: Our results indicate that CAPD therapy may induce HSPs in the peritoneal tissue, and that peritonitis in CAPD patients may be associated with the progression of peritoneal sclerosis at least through HSP47 expression and chronic macrophage infiltration. Our data also suggest that the progression of peritoneal sclerosis in such patients is associated with deterioration of peritoneal ultrafiltration function.     

Overlapping distribution of osteopontin and calcium in the ischemic core of rat brain after transient focal ischemia

Osteopontin (OPN), an adhesive glycoprotein, has recently been proposed to act as an opsonin that facilitates phagocytosis of neuronal debris by macrophages in the ischemic brain. The present study was designed to elucidate the process whereby OPN binds to neuronal cell debris in a rat model of ischemic stroke. Significant co-localization of the OPN protein and calcium deposits in the ischemic core were observed by combining alizarin red staining and OPN immunohistochemistry. In addition, electron microscopy (EM) using the osmium/potassium dichromate method revealed that electron-dense precipitates, typical of calcium deposits, were localized mainly along the periphery of putative degenerating neurites. This topical pattern of calcium precipitates resembled the distribution of OPN as detected by immunogold-silver EM. Combining immunogold-silver EM and electron probe microanalysis further demonstrated that the OPN protein was localized at the periphery of cell debris or degenerating neurites, corresponding with locally higher concentrations of calcium and phosphorus, and that the relative magnitude of OPN accumulation was comparable to that of calcium and phosphorus. These data suggest that calcium precipitation provides a matrix for the binding of the OPN protein within the debris or degenerating neurites induced by ischemic injury. Therefore, OPN binding to calcium deposits may be involved in phagocytosis of such debris, and may participate in the regulation of ectopic calcification in the ischemic brain.     

Accumulation of advanced glycation end products in the peritoneal vasculature of continuous ambulatory peritoneal dialysis patients with low ultra-filtration.

BACKGROUND: Ultra-filtration failure is a serious complication of long-term continuous ambulatory peritoneal dialysis (CAPD). This complication is related to histological changes of the peritoneum, i.e. severe interstitial fibrosis and microvascular sclerosis. Although their pathogenesis has not been elucidated yet, advanced glycation end products (AGEs) have been shown to accumulate in the peritoneal tissue of CAPD patients. METHODS: Peritoneal biopsy specimens from 14 CAPD patients with low ultra-filtration (n = 9) and high ultra-filtration (n = 5) capacity were immunohistochemically investigated using a monoclonal antibody against AGEs (6D12). The severity of peritoneal fibrosis, microvascular sclerosis and intensity of AGE accumulation were semi-quantitatively evaluated. Peritoneal ultra-filtration capacity was evaluated by calculating daily ultrafiltration volume per body weight (UFV/BW) and D/D0 (glucose) of the peritoneal equilibration test. RESULTS: In all patients with low ultra-filtration, AGE accumulated in the peritoneal fibrous tissue and microvascular walls. Remarkably, AGE accumulated more intensely in hyalinized fibrosis of small venular media. Extent of AGE accumulation in peritoneal interstitium and vascular walls correlated with the progression of interstitial fibrosis (rho = 0.727, P = 0.0088) and vascular sclerosis (rho = 0.915, P = 0.001). UFV/BW was inversely correlated to interstitial fibrosis (rho = -0.660, P = 0.0174), microvascular sclerosis (rho = -0.671, P = 0.0155) and microvascular AGE accumulation (rho = -0.678, P = 0.0145). CONCLUSIONS: In CAPD patients, AGE formation in the peritoneum correlates with the development of severe interstitial fibrosis and microvascular sclerosis, which is associated clinically with impaired peritoneal ultra-filtration.     

Minerals and bone-modulating hormones in children on continuous ambulatory peritoneal dialysis

Peritoneal fluxes of minerals and bone-modulating hormones and their impact on corresponding serum levels and bone mineralization in 7 children on continuous ambulatory peritoneal dialysis (CAPD) were studied. Most mass transfer studies revealed modest losses of calcium into peritoneal effluents. Peritoneal losses of phosphorus and magnesium, although substantial, were not sufficient to normalize hyperphosphatemia and hypermagnesemia in most patients. Parathormone and vitamin D metabolites (25-hydroxyvitamin D and 1,25-dihydroxyvitamin D) were readily detectable in peritoneal effluents. Improved bone mineral content, by sequential densitometries, was associated with amelioration of hyperparathyroidism. These data suggest that CAPD in children induces an overall improvement of disturbed mineral metabolism; nevertheless, peritoneal losses of calcium and vitamin D metabolites must be considered and replenished appropriately.     

Reversible peritoneal calcification in a patient treated by CAPD

The patient, a female, aged 65 years, developed diffuse peritoneal calcification nine years after commencing CAPD therapy. No abdominal symptoms or evidence of peritonitis were discovered during this period. Before peritoneal calcification was detected, a dialysate with a high glucose concentration (3.86%) had been used once daily for 16 months. In the case of this patient, it was not possible to discover any of the previous indicated etiologies of peritoneal calcification such as significantly elevated values for the product Ca x P, overt secondary hyperparathyroidism, or relapsing peritonitis. It was realized that the use of a high-glucose dialysate in a patient on long-term CAPD treatment had been one causative factor. After peritoneal calcification had been confirmed, the calcium concentration of the dialysate changed from 3.5 mEq/l to 2.5 mEq/l and the patient was put on a regime of 2.0 g alumigel (aluminum-containing phosphate binders) a day. Eight months later, a CT scan was taken. The peritoneal calcification has clearly been mitigated. At present, CAPD therapy is being continued in the absence of any abdominal symptoms.     

Soluble osteopontin and vascular calcification in hemodialysis patients.

BACKGROUND: Vascular calcification often occurs in patients with uremia. As osteopontin (OPN) is not only involved in the physiological but also the pathological calcification of tissues, OPN may be associated with the pathogenesis of aortic calcification in hemodialysis (HD) patients. METHODS: We examined the expression of OPN in atherosclerotic aortas of HD patients. In addition, we performed a prospective longitudinal study by using CT scans to detect aortic calcifications and by measuring the plasma OPN concentration by ELISA in HD patients (20 men, 16 women; mean age 55.2 +/- 21.3 years) and in healthy volunteers (18 men, 17 women; mean age 54.0 +/- 13.2 years). RESULTS: By immunohistochemical staining, OPN was abundantly localized in atherosclerotic plaques of HD patients. The macrophages surrounding the atheromatous plaques were identified as the OPN-expressing cells. We furthermore found that the concentration of soluble plasma OPN was significantly higher in HD patients as compared with the concentrations in age-matched healthy volunteers (837.3 +/- 443.2 vs. 315.1 +/- 117.4 ng/ml, p < 0.01). The OPN concentration was positively correlated with the aortic calcification index in HD patients (r = 0.749, p < 0.01). CONCLUSION: These data suggest that OPN, secreted by macrophages, plays a role in the calcification of atheromatous plaques in HD patients.     

Antisense oligonucleotides against collagen-binding stress protein HSP47 suppress peritoneal fibrosis in rats

BACKGROUND: Peritoneal fibrosis is a serious complication in patients on continuous ambulatory peritoneal dialysis (CAPD), but the molecular mechanism of this process remains unclear. Heat shock protein 47 (HSP47), a collagen-specific molecular chaperone, is essential for biosynthesis and secretion of collagen molecules, and is expressed in the tissue of human peritoneal fibrosis. In the present study, we examined the effect of HSP47 antisense oligonucleotides (ODNs) on the development of experimental peritoneal fibrosis induced by daily intraperitoneal injections of chlorhexidine gluconate (CG). METHODS: HSP47 antisense or sense ODNs were injected simultaneously with CG from day 14, after injections of CG alone. Peritoneal tissue was dissected out 28 days after CG injection. The expression patterns of HSP47, type I and type III collagen, alpha-smooth muscle actin (alpha-SMA), as a marker of myofibroblasts, ED-1 (as a marker of macrophages), and factor VIII were examined by immunohistochemistry. RESULTS: In rats treated with CG alone, the submesothelial collagenous compact zone was thickened, where the expression levels of HSP47, type I and type III collagen and alpha-SMA were increased. Marked macrophage infiltration was also noted and the number of vessels positively stained for factor VIII increased in the CG-treated group. Treatment with antisense ODNs, but not sense ODNs, abrogated CG-induced changes in the expression of HSP47, type I and III collagen, alpha-SMA, and the number of infiltrating macrophages and vessels. CONCLUSION: Our results indicate the involvement of HSP47 in the progression of peritoneal fibrosis and that inhibition of HSP47 expression might merit further clinical investigation for the treatment of peritoneal fibrosis in CAPD patients.     

Improvement of peritoneal calcification after parathyroidectomy in a peritoneal dialysis patient

Peritoneal calcification is one of the complications of peritoneal dialysis (PD). It can become serious, leading to severe abdominal pain and even death. Possible mediators of peritoneal calcification in PD patients are assumed to include acetate buffer, overdosage of vitamin D, repeated peritonitis, hypertonic dialysate, calciphylaxis and secondary hyperparathyroidism (SHPT). However, the mechanism and treatment of peritoneal calcification are controversial. Few reports have appeared on improvement of peritoneal calcification after parathyroidectomy (PTX) for SHPT of long duration. We report herein the case of a 48-year-old man on dialysis for 17 years including PD for 14 years. In 1989, he was admitted to hospital because of end-stage renal disease (ESRD), and started treatment with PD. Abdominal computed tomography (CT) first showed peritoneal calcification in August 2002. Peritoneal calcification did not improve despite conventional treatment including discontinuation of PD, control of calcium phosphate product to less than 55 mg2/dl2, removal of the peritoneal catheter and empirical prednisolone (PSL) usage. The intact parathyroid hormone (i-PTH) level was increased over 1,000 pg/ml and extra-osseous calcification occurred. Total PTX was performed in November 2004. Postoperatively, the i-PTH level decreased immediately and calcium phosphate product was maintained in the reference range. Abdominal CT after PTX showed improvement of peritoneal calcification in September 2005. It appeared that PTX could be used to treat patients with persistent peritoneal calcification not responding to conventional treatment. It was postulated that SHPT might play a crucial role in accelerating peritoneal calcification in PD patients.     

Prevalence and influencing factors of peritoneal calcification in patients with long peritoneal dialysis duration

Objective To investigate the prevalence and related factors of peritoneal calcification in peritoneal dialysis (PD) patients with long dialysis duration, and to explore the relationship between peritoneal calcification and vascular calcification. Methods This cross-section study enrolled PD patients who had received PD for more than 4 years in Peking University People's Hospital. Peritoneal calcification and abdominal aortic calcification were reviewed by CT scan. Demographic data, clinical characteristics, laboratory data including calcium phosphorus metabolism indexes (Ca, P, ALP and iPTH) and PD adequacy were collected. The influencing factors of peritoneal calcification were analyzed by Logistic regression analysis. The correlation between peritoneal calcification and abdominal aortic calcification were tested by Spearman correlation analysis. SPSS 19.0 was used for statistical analysis. Results (1) Seventy-nine PD patients were enrolled: 32 males (40.5%); mean age was (58.7±13.1) years and average PD duration was 77.25(58.00, 88.00) months. The major primary diseases were glomerulonephritis (46.8%) and diabetic nephropathy (30.4%). (2) 6 patients (7.6%) had CT-detectable peritoneal calcification. 77(97.5%) patients were found with various degrees of peritoneal thickening. The prevalence of peritoneal calcification was 7.6% in patients with PD duration more than 4 years, 10.3% in patients with PD duration more than 6 years, 18.8% in patients with PD duration more than 8 years and 40.0% in patients with PD duration more than 10 years, showing an increasing trend. Compared with non-peritoneal calcification group, the patients in peritoneal calcification group received higher doses of Vitamin D (P＜0.001) and lower triglyceride levels (P=0.041). The patients were divided into two groups according to whether dialysis duration was longer than 9 years, and the proportion of patients with long PD duration in peritoneal calcification group was higher (P=0.013). Logistic regression analysis showed that PD duration, calcium and phosphorus metabolism indexes were not independent risk factors of peritoneal calcification. High vitamin D dose was an independent risk factor for peritoneal calcification (B=2.667, OR=14.394, 95%CI 1.655 - 125.165, P=0.016). (3) 74 patients were found with abdominal aortic calcification in different degrees, and the prevalence rate of abdominal aortic calcification was 93.7%. Spearman correlation analysis showed that there was no correlation between peritoneal calcification and vascular calcification (r=0.70, P=0.542). Conclusions The prevalence of peritoneal calcification in long PD duration patients is low. Peritoneal calcification may be associated with high Vitamin D dose and long PD duration.     

Intraperitoneal production of erythropoietin with continuous ambulatory peritoneal dialysis

Higher hematocrit and serum erythropoietin (EPO) levels have previously been shown in end-stage renal disease patients treated with continuous ambulatory peritoneal dialysis (CAPD) compared with hemodialysis. We investigated whether EPO was produced intraperitoneally in CAPD patients. EPO concentration was 3.5±0.3 mU/ml by radioimmunoassay in 26 samples of peritoneal dialysis effluent obtained from 15 CAPD patients. EPO was not detectable in the fresh unused dialysate. No correlation was observed between EPO levels in the serum and dialysis effluent. Peritoneal macrophages were isolated from the dialysis effluent of 9 CAPD patients after an overnight dwell. The culture supernatant obtained after 24 h of in vitro culture of a million cells yielded EPO of 3.5±0.3 mU/ml. Our study demonstrated that peritoneal macrophages from CAPD patients produce EPO on in vitro stimulation, and EPO is present in the dialysis effluent of CAPD patients.     

Characterisation of the mitogenic-induced capacity of peritoneal effluent on human and mice fibroblasts in culture

During continuous ambulatory peritoneal dialysis, solutes capable of stimulating fibroblast activity could be transferred into dialysate; their significance and consequences remain to be established. Sixty-three stable non-selected patients on CAPD were included in this study. Peritoneal transport for water and small solutes was assessed. To explore the mitogenic-induced capacity of peritoneal nocturnal effluent, 50 microliters were added to culture plates of mice and human fibroblasts. Peritoneal effluent alone shows a mitogenic potency slightly greater than insulin and clearly less than bovine fetal serum. When coadjuvants are added, mitogenicity increases but in a variable manner among patients. No differences can be observed in relation to diabetes mellitus, time on CAPD, previous peritonitis, and losses of diffusion capacity. We noted significant inverse linear correlations between mitogenicity value and ultrafiltration, effluent calcium, and creatinine. Neither adrenergic nor calcium-channel blockers influenced these values. We conclude that the peritoneal effluent of CAPD patients has a variable effect on fibroblast growth. Some of the blood components seem to be implicated in this activity. Reduced peritoneal ultrafiltration capacity, probably by a concentration mechanism, is related to a greater mitogenic potency in peritoneal effluent. CAPD patients with impaired ultrafiltration may be at high risk for autoactivation of peritoneal fibroblasts, mainly in mesothelial denudate states.     

Hepatocyte growth factor prevents peritoneal fibrosis in an animal model of encapsulating peritoneal sclerosis

BACKGROUND: Ultrafiltration failure associated with peritoneal fibrosis can lead patients to discontinue continuous ambulatory peritoneal dialysis (CAPD). It has been reported that the reciprocal imbalance between transforming growth factor-beta1 (TGF-beta1) and hepatocyte growth factor (HGF) is closely involved in the progression of tissue fibrosis. We previously showed that exogenous HGF restores the growth of human peritoneal mesothelial cells suppressed by a high concentration of D-glucose or TGF-beta1. In this study, we examined whether constitutive exposure to HGF prevents peritoneal fibrosis in an animal model of encapsulating peritoneal sclerosis (EPS). METHODS: To establish the model, a daily intraperitoneal injection of 0.1% chlorhexidine gluconate was given to male Wister rats for 35 days. Rat peritoneal mesothelial cells (RPMCs) transfected with full-length human HGF cDNA in an expression vector (pUCSRalpha/HGF) were injected into the peritoneal cavity of the rats. Thereafter, pathological changes to the peritoneal membrane were observed, and the effect on peritoneal ultrafiltration volume was examined. RESULTS: In the model, microscopic examination revealed a progressive thickening of the submesothelial layer, and an increase in the number of capillary vessels. Peritoneal ultrafiltration volume was decreased. Interestingly, the pathological changes to the peritoneal membrane were reversed by the intraperitoneal injection of pUCSRalpha/HGF-transfected RPMCs. Furthermore, peritoneal ultrafiltration volume was increased. CONCLUSIONS: The constitutive production of HGF by UCSRalpha/HGF-transfected RPMCs can improve peritoneal fibrosis resulting in an increase in peritoneal ultrafiltration volume. This approach may have clinical application.     

尿毒症血清诱导的磷酸钙晶体对人主动脉平滑肌细胞的钙化作用

目的 探讨尿毒症患者血清诱导的磷酸钙晶体对人主动脉平滑肌细胞(HASMCs)钙化的影响.方法 尿毒症患者血清在37℃下孵育3d,超速离心法从尿毒症血清中分离磷酸钙晶体和无晶体血清,采用扫描电子显微镜和能量色散X射线光谱仪分析晶体的形态及化学特征.体外培养HASMCs,分为以下4组:对照组、尿毒症血清组、磷酸钙晶体组和无晶体血清组.茜素红染色及甲氧酚酞络合酮法检测HASMCs钙化结节的形成及细胞内钙含量.实时荧光定量PCR法检测骨形态发生蛋白2(BMP-2)、骨桥蛋白(OPN)、核结合因子α1亚基(Cbfα1)、碱性磷酸酶(ALP)、基质γ羧基谷氨酸蛋白(MGP)的mRNA表达.Cbfα1、OPN和BMP-2的蛋白表达用Westcrn印迹和ELISA法检测.结果 尿毒症血清可诱导磷酸钙晶体形成.与对照组相比,尿毒症血清明显促进HASMCs钙化结节形成,增加细胞内钙含量(P＜0.05),并上调细胞BMP-2、OPN、Cbfα1的mRNA和蛋白表达(均P＜ 0.01);而磷酸钙晶体亦促进HASMCs钙化结节的形成,增加细胞内钙含量(P＜0.05),上调BMP-2、OPN、Cbfα1的mRNA和蛋白表达(均P＜0.01).无晶体血清组的HASMCs胞内钙含量和上述成骨蛋白的表达与对照组差异无统计学意义(均P＞ 0.05).结论 尿毒症血清可能通过诱导磷酸钙晶体的形成促进血管钙化的发生.     

Immunohistochemical detection of an AGE,a ligand for macrophage receptor,in peritoneum of CAPD patients

BACKGROUND: In patients on long-term continuous ambulatory peritoneal dialysis (CAPD), ultrafiltration (UF) capacity of peritoneal membrane may be impaired due to accumulation of advanced glycation end products (AGEs). This study aimed to elucidate the characteristics of a novel anti-AGE antibody, ODI-GLC19, and to demonstrate AGE accumulation in the peritoneum of CAPD patients using the antibody. METHODS: A monoclonal anti-AGE antibody (ODI-GLC19) was prepared by immunizing female balb/c mice using D-glucose-modified keyhole limpet hemocyanin. The characteristics of ODI-GLC19 were determined by enzyme-linked immunosorbent assay and receptor binding inhibition assay. Immunohistochemistry using ODI-GLC19 was performed to detect AGE in peritoneal tissues obtained from patients with nonrenal disease, and CAPD patients with normal and low UF. RESULTS: ODI-GLC19 reacted with glycolaldehyde-modified BSA (GA-BSA) and glucose-modified BSA (GLC-BSA), but not with imidazolone or N epsilon-(carboxymethyl)lysine. GA-BSA and GLC-BSA strongly bound to cultured macrophages. Time-dependent recognition of newly formed GA-BSA by ODI-GLC19 was similar to that by macrophages. The binding of GA-BSA to macrophages was inhibited by ODI-GLC19 in a dose-dependent manner. Immunohistochemical studies revealed that ODI-GLC19-positive AGE was exclusively detected in peritoneal cells including macrophages, and its staining intensity was more prominent in the peritoneum of CAPD patients, especially with low UF, than in patients with nonrenal disease. CONCLUSIONS: A novel monoclonal anti-AGE antibody, ODI-GLC19, recognizes a ligand for an AGE receptor on macrophages. Incorporation of AGE into peritoneal cells including macrophages may be involved in progressive peritoneal dysfunction in CAPD patients.     

Peritoneal kinetics in children undergoing continuous ambulatory/cycling peritoneal dialysis

We present a report on peritoneal kinetics in children undergoing continuous ambulatory/cycling peritoneal dialysis (CAPD/CCPD). The effect of long-term treatment with CAPD/CCPD, peritonitis episodes, and dialysate inflow volume on peritoneal kinetics in children was evaluated. Peritoneal kinetic studies (PKSs) were performed in 47 pediatric patients at different times following initiation of CAPD/CCPD. In 18 of these patients, PKSs were repeated up to four times with an unchanged dialysate inflow volume after up to 55 months of CAPD/CCPD treatment. The PKS consisted of a 120-minute dwell with a 1.5% dextrose dialysate solution. Peritoneal clearance, dialysance, and dialysate to plasma (D/P) concentration ratios were calculated after 30, 60, and 120 minutes. The results of the serial PKSs demonstrate stable peritoneal creatinine and urea-N clearance, dialysance or D/P concentration ratios. Furthermore, there was no adverse effect of 32 peritonitis episodes. Finally, inflow volumes correlated directly with clearances of creatinine (P less than .01), urea-N (P less than .001), and potassium (P less than .001), and there was an inverse relationship to the D/P concentration ratios of creatinine (P less than .01), urea-N (P less than .01), potassium (P less than .01), and uric acid (P less than .01). Thus, CAPD/CCPD is a useful and effective long-term treatment modality for pediatric patients. Maximal dialysate inflow volumes should be provided to enhance peritoneal kinetics.     

Peritoneal sodium mass removal in continuous ambulatory peritoneal dialysis and automated peritoneal dialysis: influence on blood pressure control.

BACKGROUND/AIM: Sodium and water retention is common in peritoneal dialysis patients and contributes to cardiovascular disease. As peritoneal sodium removal depends partly on dwell time, and automated peritoneal dialysis (APD) often uses short dwell time exchanges, the aim of this study was to compare the 24-hour peritoneal sodium removal in APD and standard continuous ambulatory peritoneal dialysis (CAPD) patients and to analyze its possible influence on blood pressure control. METHODS: A total of 53 sodium balance studies (30 in APD and 23 in CAPD) were performed in 36 stable peritoneal dialysis patients. The 24-hour net removal of sodium was calculated as follows: M = ViCi - VdCd, where Vd is the 24-hour drained volume, Cd is the solute sodium concentration in Vd, Vi is the amount of solution used during a 24-hour period, and Ci is the sodium concentration in Vi. Peritoneal sodium removal was compared between APD and CAPD patients. Residual renal function, serum sodium concentration, daily urinary sodium losses, weekly peritoneal Kt/V and creatinine clearance, 4-hour dialysate/plasma creatinine ratio, proportion of hypertonic solutions, net ultrafiltration, systolic and diastolic blood pressures, and need for antihypertensive therapy were also compared between the groups. RESULTS: Peritoneal sodium removal was higher (p < 0.001) in CAPD than in APD patients. There were no significant differences in residual renal function, serum sodium concentration, urinary sodium losses, peritoneal urea or creatinine clearances, 4-hour dialysate/plasma creatinine ratio, or proportion of hypertonic solutions between groups. The net ultrafiltration was higher in CAPD patients and correlated strongly (r = 0.82; p < 0.001) with peritoneal sodium removal. In APD patients, peritoneal sodium removal increased significantly only in those patients with a second daytime exchange. The systolic blood pressure was higher (p < 0.05) in APD patients, and the proportion of patients with antihypertensive therapy was also higher in APD patients, although no significant relationship between blood pressure values and amount of peritoneal sodium removal was found. CONCLUSIONS: The 24-hour sodium removal is higher in CAPD than in APD patients, and there is a trend towards better hypertension control in CAPD patients. As hypertension control and volume status are important indices of peritoneal dialysis adequacy, our results have to be considered in the choice of the peritoneal dialysis modality.     

Hyperphosphatemia-induced nanocrystals upregulate the expression of bone morphogenetic protein-2 and osteopontin genes in mouse smooth muscle cells in vitro

Vascular calcification, which contributes to cardiovascular disease in patients with uremic hyperphosphatemia, is associated with vascular cell expression of osteogenic genes, including bone morphogenetic protein (BMP)-2 and osteopontin (OPN). High inorganic phosphate levels in vitro stimulate the osteogenic conversion of smooth muscle cells; however, the mechanism governing this is not clear. We found that high-phosphate medium increased the expression of BMP-2 and OPN in mouse smooth muscle cells in culture. However, this effect was lost in the presence of the mineralization inhibitor, pyrophosphate, suggesting a contribution of calcium phosphate crystals. Addition of 1-2?mmol/l phosphate alone to growth medium was sufficient to induce nanosized crystals after 1 day at 37?°C. Isolated crystals were about 160?nm in diameter and had a calcium to phosphate ratio of 1.35, consistent with the hydroxyapatite precursor octacalcium phosphate. Nanocrystal formation increased fourfold in the absence of serum, was blocked by fetuin-A, and was dependent on time and on the concentrations of phosphate and calcium. Purified synthetic hydroxyapatite nanocrystals and isolated high-phosphate-induced nanocrystals, but not nanocrystal-free high-phosphate medium, also induced BMP-2 and OPN. Thus, our results suggest that BMP-2 and OPN are induced by calcium phosphate nanocrystals, rather than soluble phosphate. This mechanism may contribute, in part, to hyperphosphatemia-related vascular cell differentiation and calcification.     

普伐他汀抑制肿瘤坏死因子α介导的人脐动脉血管平滑肌细胞成骨样钙化

目的 研究普伐他汀干预对肿瘤坏死因子α（TNF-α）介导的人脐动脉血管平滑肌细胞（hUASMC）成骨样分化标志蛋白骨特异性碱性磷酸酶（BAP）、骨桥蛋白（OPN）和骨形成蛋白2（BMP-2）表达以及细胞外钙盐沉积的影响，并探讨普伐他汀在血管钙化防治中的潜在作用。 方法 植块贴壁法原代培养人hUASMC。予以TNF-α刺激和普伐他汀干预，甲O-酚酞络合酮方法测定细胞外基质钙盐沉积；实时定量PCR法观察血管平滑肌细胞BAP和OPN mRNA表达水平；免疫印迹法观察血管平滑肌细胞BAP、OPN和BMP-2蛋白表达水平。 结果一定浓度范围的普伐他汀呈浓度依赖方式抑制TNF-α对hUASMC的促增殖作用（r = －0.946，P < 0.01）；一定浓度范围的普伐他汀呈浓度依赖方式下调TNF-α介导上调的BAP、OPN mRNA表达（r = －0.972，P < 0.01）与蛋白的表达水平（BAP蛋白，r = －0.820，P < 0.01；OPN蛋白，r = －0.972，P < 0.01；BMP-2蛋白，r = －0.928，P < 0.01），抑制血管平滑肌细胞成骨样分化，减少细胞外基质钙盐的沉积（r = －0.973，P < 0.01）。 结论 普伐他汀可抑制TNF-α对hUASMC的促增殖作用，抑制细胞成骨样分化，减少细胞外基质钙盐的沉积。     

Peritoneal transport characteristics and dwelling time significantly impact ghrelin clearance in peritoneal dialysis patients.

BACKGROUND: Plasma ghrelin exerts widespread bioactivities. Although it is effectively removed from the blood by a single course of haemodialysis, peritoneal clearance of ghrelin is uncertain. Our study aimed to determine (i) whether there is a correlation between plasma ghrelin levels and characteristics of peritoneal ghrelin clearance, and (ii) whether plasma ghrelin levels significantly impact markers of mortality or morbidity in continuous ambulatory peritoneal dialysis (CAPD) patients. METHODS: We enrolled 50 qualified CAPD patients. Blood was drawn during the fasting state and 2 h post-prandially. Also during these periods, peritoneal effluents were collected for radioimmunoassay of total plasma ghrelin level and measurement of other parameters. Twenty-four hour ascites were collected for determination of ghrelin daily mass transfer. RESULTS: Peritoneal ghrelin clearance was positively correlated with the dialysate-peritoneal creatinine (D/P(Cr)) ratio. Fasting plasma ghrelin levels were inversely correlated with the peritoneal/plasma (D/P(ghrelin)) ratio (P = 0.045). Plasma ghrelin levels were negatively correlated with body mass index, waist-hip ratio, fasting insulin and triglyceride level, and positively correlated with lean body mass. Plasma ghrelin levels were positively correlated with left ventricular mass (LVM), left ventricular mass index and blood pressure. CONCLUSIONS: Peritoneal transporter characteristics may modulate plasma ghrelin levels in CAPD subjects. By contributing to the level of plasma ghrelin, dwelling time may have an impact on LVM and associated morbidity in CAPD patients.     

Diffusion of HCV through peritoneal membrane in HCV positive patients treated with continuous ambulatory peritoneal dialysis

Purpose of the Study. We evaluated the presence of HCV in the peritoneal effluents of viraemic patients treated with continuous ambulatory peritoneal dialysis (CAPD) to evaluate the risk of transmitting the infection with this procedure. Procedure. Fifteen of 81 CAPD patients (18.5%) had anti-HCV antibodies and eight were viraemic. At the beginning of CAPD two of the viraemic patients had ascites with a clinical picture of chronic active hepatitis and cirrhosis. Peritoneal dialysates were collected after an overnight exchange with 1.36% glucose and after a 4-h exchange with 3.86% glucose. Fluids from the overnight exchange were spun to obtain a cellular pellet and the supernatant 100-fold concentrated. Results. No viral genome could be detected in unconcentrated samples and in cellular pellets, while HCV-RNA at low titre was detected in concentrated dialysates from the two patients with active liver disease. Conclusions. Our findings confirm that HCV may be present in the CAPD effluent of some patients; however, the titre of virus in the effluent was extremely low, at the limit of detection of the PCR assay. Peritoneal fluids originating from patients with HCV associated severe liver disease may be a potential source of infection.