Dialysate In Peritoneal Dialysis Patients Research Articles

A STUDY ON DIALYSATE GLUCOSE CONCENTRATION IN PATIENTS WITH CONTINUOUS AMBULATORY PERITONEAL DIALYSIS

Background: Glucose-based peritoneal dialysis (PD) is the predominantly used dialysate in PD patients. Glucose absorption in peritoneal dialysis (PD) patients may contribute to adverse metabolic complications. The impact of high peritoneal dialysate glucose concentration (PDGC) on all-cause as well as cardiovascular disease (CVD) mortality in peritoneal dialysis (PD) patients is unclear. The current researchs widely applied formulae may be not suitable for estimation of glucose absorption in continuous ambulatory peritoneal dialysis (CAPD) patients. Objective: This study examined the actual glucose absorption in a cohort of CAPD patients and compared the results with estimates from three current formulae. Our study provides an overview of glucose associated metabolic complications and to investigate the impact of high glucose in dialysate on our CAPD patients. Methods: We conducted a survey of glucose absorption of a cohort of 56 CAPD patients and compared actual dialysate glucose absorbed with the one of K/DOQI formula, Grodstein formula, or a percentage estimate of 60%. Results: The total dialysate glucose infused each day varied from 108.8 to 181.6 g/day with average of 130±19.6 g, with the mean glucose concentration in dialysate is 1.79%. The average of glucose absorbed was 83.2±24.3 g/day (ranging from 28.6 to 145.2 g) by actual measurements. The mean absorption rate was 64.1% (ranging from 22.6% to 99.6%). There are no significant differences between 4 methods estimating glucose absorption in CAPD patients. There are strong correlations between glucose concentration using in PD patients with levels of total cholesterol, triglyceride, urea, creatinine and uric acid. Only triglyceride concentration associated with glucose absorption from dialysate. Conclusions: The applications of current estimating methods may have limitations. The actual measurement providesdietitians and doctors more exact information of absorbed glucose and energy compared to the current estimating methods. Key words: dialysate, Glucose absorption, peritoneal dialysis, continuous ambulatory peritoneal dialysis, acid uric, triglyceride

Assessment of the size selectivity of peritoneal permeability by the restriction coefficient to protein transport.

Transport of serum proteins from the circulation to peritoneal dialysate in peritoneal dialysis patients mainly focused on total protein. Individual proteins have hardly been studied. We determined serum and effluent concentrations of four individual proteins with a wide molecular weight range routinely in the standardised peritoneal permeability analysis performed yearly in all participating patients. These include β2-microglobulin, albumin, immunoglobulin G and α2-macroglobulin. The dependency of transport of these proteins on their molecular weight and diffusion coefficient led to the development of the peritoneal protein restriction coefficient (PPRC), which is the slope of the relation between the peritoneal clearances of these proteins and their free diffusion coefficients in water, when plotted on a double logarithmic scale. The higher the PPRC, the more size restriction to transport. In this review, we discuss the results obtained on the PPRC under various conditions, such as effects of various osmotic agents, vasoactive drugs, peritonitis and the hydrostatic pressure gradient. Long-term follow-up of patients shows an increase of the PPRC, the possible causes of which are discussed. Venous vasculopathy of the peritoneal microcirculation is the most likely explanation.

MO685PRESENCE OF SARS-COV-2 ANTIBODIES IN SPENT PERITONEAL DIALYSATE

Background and AimsInfection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) elicits cellular and humoral immune responses. In patients with coronavirus disease 2019 (COVID-19), IgM, IgA, and IgG antibodies against SARS-CoV-2 emerge within a few days and can be detected in several body fluids, such as serum and oral fluids. End Stage Kidney Disease patients are especially vulnerable in this pandemic as they are immunocompromised, putting them at higher risks of infection and impaired response to vaccines. While repeated blood draws in hemodialysis patients pose no substantial medical or logistic problems, the situation is different in those treated by peritoneal dialysis. To overcome that limitation, we explored the presence or absence of SARS-CoV-2 antibodies in spent peritoneal dialysate in patients treated with acute and chronic peritoneal dialysis, respectively.MethodWe analyzed spent PD dialysate samples from four distinct patient groups, namely Pre-Covid-19 controls (Group 1; 15 samples collected between May 2019 and Feb 2020), Covid-19 negative controls during ongoing pandemic (Group 2; 33 samples collected between March and September 2020); chronic PD patients with confirmed Covid-19 (Group 3; 30 samples collected between March and September 2020,); and patients with confirmed Covid-19 and acute kidney injury treated with acute PD (Group 4; 18 samples collected in April 2020).SARS-CoV-2 IgG titer in spent PD dialysate was measured by enzyme-linked immunosorbent assay (ELISA) targeting Nucleocapsid (N) protein of SARS-CoV-2 virus (MPBIO cat#: 08440100). Total SARS-CoV-2 antibodies (IgG, IgM, and IgA) were measured using ELISA targeting recombinant N Protein and Spike protein (S Protein) (AFFYPRO Cat#: EA821). Absolute IgG concentration was calculated using IgG standard provided by the MPBIO ELISA kit. The total antibody titer was calculated as a relative value to the mean of antibody levels of COVID-19 negative patients. To account for different dialysate and ultrafiltration volumes, antibody titers were also normalized to total protein concentrations in the spent dialysate samples. The ratio of IgG or total antibody to total protein reflects the normalized titer.ResultsNormalized anti-SARS-CoV-2 IgG titer in the four groups is illustrated in Figure 1A. The mean IgG/protein levels in Group 3 and Group 4 are 86-fold (p=0.023) and 220-fold (p=0.0003), respectively, above the mean IgG/protein levels in COVID negative patients (Group 1 and 2 combined). The discrimination between patients with and without COVID-19 is excellent (AUC 0.938). At a threshold of 0.0024%, the sensitivity and specificity are 89.6% and 97.9%, respectively (Figure 1B). Using same threshold as Figure 1B, in Group 3, 9 out of 11 patients had a positive IgG response in all samples. In 5 patients, IgG levels decreased over time. The mean normalized total antibody/protein levels in Group 3 and Group 4 are 7.3-fold and 24-fold above those in COVID negative patients (combined Group 1 and 2; both p<0.001). Distribution pattern, ROC analysis, and dynamic change over time of total SARS-CoV-2 antibodies are like those of IgG (Figure 1D-F).ConclusionCovid-19 serology tests can provide much information including diagnosis, immune response, local seroprevalence, et al. Currently, most of serology tests are done using blood-related specimens. To our knowledge, this is the first study reporting SARS-CoV-2 antibodies in spent PD dialysate. Presence of SARS-CoV-2 antibodies in spent PD dialysate of peritoneal dialysis patients potentially provides a new way to perform frequent serology tests for this high-risk group. As USA is moving fast on national vaccination at this moment, using test strip developed for PD effluent to quickly and frequently check SARS-CoV-2 antibody in PD effluent could be used to monitor the vaccination efficiency while avoiding clinic visit.

Diagnosis of bacterial pathogens in the dialysate of peritoneal dialysis patients with peritonitis using surface-enhanced Raman spectroscopy

BackgroundBacterial peritonitis is the most common cause of peritoneal dialysis (PD) therapy drop-out. A quick and accurate diagnosis of the bacterial pathogen can reduce the PD drop-out rate. Surface-enhanced Raman spectroscopy (SERS) can rapidly identify bacteria using chips coated with nano-sized metal particles. MethodsKnown bacteria were loaded in the SERS-chips and illuminated with laser light to establish a reference Raman spectra library. Dialysate from PD peritonitis patients was concentrated by centrifuge and examined with the same SERS, and the resulting Raman spectra were compared with library spectra for bacteria identification. Principal component analysis was used for further confirmation. The same batches of dialysate were sent to routine culture as a reference bacteria identification method. The results of the 2 identification methods were compared. ResultsA total of 43 paired-samples were sent for study. There were 37 samples with bacteria identified but 6 were culture-negative by the reference method. 31 bacteria were identified in paired-samples by SERS, among which, 29 bacteria were exactly the same as those identified by the reference method. Bacteria not included in the reference library spectra cannot be identified. ConclusionsSERS techniques can rapidly identify bacterial pathogens in the dialysate of PD peritonitis patients.

Association of tumour necrosis factor-α polymorphism in patients with end stage renal disease.

Cytokines play a critical role in the pathophysiology of end stage renal disease (ESRD). Tumour necrosis factor-a (TNF-α) is an important cytokine involved in initiation and progression of renal diseases. The present study evaluated the association of specific alleles/genotype of TNF-α with chronic renal failure (CRF) and ESRD. A total of 30 CRF patients who were not on renal replacement therapy, 85 ESRD patients and 120 healthy controls were included in the study. The ESRD patients belonged to two subgroups: patients on peritoneal dialysis (PD) without peritonitis (n = 50) and with peritonitis (n = 35). TNF-α genotype (-308 G > A) was determined by polymerase chain reaction-restriction fragment length polymorphism. Level of TNF-α was detected in the sera of patients and healthy controls by enzyme linked immunosorbent assay (ELISA), and also in the dialysate of patients on PD. The genotypic distributions of TNF-α (-308 G > A) were significantly different between patients and controls. Homozygous A/A genotype had significant association with CRF and ESRD (P < 0.001, odds ratio [OR] = 25.02). Frequency of homozygous A/A genotype was significantly higher in all subgroups of patients than controls (CRF 40% vs control 2.5%, P = 0.001; PD 54% vs control 2.5%, P < 0.001 and PD with peritonitis 62.8% vs control 2.5%, P < 0.001). Patients with homozygous A/A genotype had significantly elevated levels of TNF-α in the sera of patients and in the dialysate of PD patients. Individuals with homozygous TNF-α (-308 G > A) polymorphisms has significant association with CRF and ESRD, and thus may be a predictor for development of the disease. Elevated TNF-α may be a contributory factor.

Patients with encapsulating peritoneal sclerosis have increased peritoneal expression of connective tissue growth factor (CCN2), transforming growth factor-β1, and vascular endothelial growth factor.

IntroductionEncapsulating peritoneal sclerosis (EPS) is a devastating complication of peritoneal dialysis (PD). The pathogenesis is not exactly known and no preventive strategy or targeted medical therapy is available. CCN2 has both pro-fibrotic and pro-angiogenic actions and appears an attractive target. Therefore, we studied peritoneal expression of CCN2, as well as TGFβ1 and VEGF, in different stages of peritoneal fibrosis.Materials and methodsSixteen PD patients were investigated and compared to 12 hemodialysis patients and four pre-emptively transplanted patients. Furthermore, expression was investigated in 12 EPS patients in comparison with 13 PD and 12 non-PD patients without EPS. Peritoneal tissue was taken during kidney transplantation procedure or during EPS surgery. In a subset of patients, CCN2 protein levels in peritoneal effluent and plasma were determined. Samples were examined by qPCR, histology, immunohistochemistry, and ELISA.ResultsPeritoneal CCN2 expression was 5-fold higher in PD patients compared to pre-emptively transplanted patients (P<0.05), but did not differ from hemodialysis patients. Peritoneal expression of TGFβ1 and VEGF were not different between the three groups; neither was peritoneal thickness. Peritoneum of EPS patients exhibited increased expression of CCN2 (35-fold, P<0.001), TGFβ1 (24-fold, P<0.05), and VEGF (77-fold, P<0.001) compared to PD patients without EPS. In EPS patients, CCN2 protein was mainly localized in peritoneal endothelial cells and fibroblasts. CCN2 protein levels were significantly higher in peritoneal effluent of EPS patients compared to levels in dialysate of PD patients (12.0±4.5 vs. 0.91±0.92 ng/ml, P<0.01), while plasma CCN2 levels were not increased.ConclusionsPeritoneal expression of CCN2, TGFβ1, and VEGF are significantly increased in EPS patients. In early stages of peritoneal fibrosis, only CCN2 expression is slightly increased. Peritoneal CCN2 overexpression in EPS patients is a locally driven response. The potential of CCN2 as biomarker and target for CCN2-inhibiting agents to prevent or treat EPS warrants further study.

Experience in Primary Culture of Human Peritoneal Mesothelial Cell

To compare the growth condition between different sources and different culture environments, mesothelial cells were isolated from omentum and peritoneal dialysate effluent (PDE), seeded at different densities (5 × 10⁵, 1 × 10⁵, 5 × 10⁴, 1 × 10⁴, 5 × 10³, 1 × 10³ and 5 × 10² cells/cm², respectively), supported with different fetal calf serum (FCS) concentrations (3%, 6%, 10% and 15%) and grown in dishes with and without gelatin pre-coating. Growth condition was evaluated by simple morphological observation. Cells phenotype was examined by immunofluorescent staining. The results showed that omentum-derived mesothelial cells generally showed a uniform growth pattern with good quality. Alternatively, there was a wide patient-to-patient variation in PDE-derived culture. Heterogeneous colonies composed of a mixture of large, small or abortive mesothelial colonies as well as fibroblastoid colonies were frequently observed. A minimum seeding density of 5 × 10³ cells/cm² is required for the omentum-derived mesothelial cells to grow to confluent monolayer (1-5 × 10⁴ cells/cm² for initial culture from fresh PDE). Appropriate seeding density is always associated with successful culture in omentumbased culture, but not in PDE-based culture. Mesothelial cells could grow to confluency regardless of FCS concentration and gelatin pre-coating. However, growth rate was slower in lower FCS concentrations and on dishes without gelatin coating. Most cells in culture expressed cytokeratin and vimentin, but not VWF. Alpha-smooth muscle actin frequently appeared in cytokeratin+ mesothelial cells, especially in higher FCS concentrations and in PDE-derived culture. Our data demonstrate that PDE, in contrast to omentum, provides a source of mesothelial cells with poor and unstable quality for primary culture. Healthy cell quality and sufficient seeding density seem to be the most important factors for successful culture of mesothelial cells. The frequent occurrence of epithelial-to-mesenchymal transition in cultured mesothelial cells indicates the feasibility of mesothelial cells to undergo phenotype change upon environment changes, especially following chronic exposure to uremic environment and dialysate in peritoneal dialysis patients.

Identification of Hepatitis C Virus RNA in Peritoneal Dialysis Fluid of Patients with Viremia

The potential risk for transmission of hepatitis C virus (HCV) by peritoneal dialysis (PD) has been studied previously, with conflicting results. To assess whether HCV crosses the peritoneal membrane, the following determinations were performed in 16 patients (7 males, 9 females; mean age 41.8 years; mean time on PD 14 +/- 15 months) undergoing PD: serum anti-HCV using second-generation enzyme-linked immunosorbent assay (ELISA), serum and PD fluid HCV RNA by nested polymerase chain reaction, HCV genotyping by restriction fragment length polymorphism, and serum HCV load by branched DNA assay. Anti-HCV was positive in 10 patients. Serum HCV RNA was positive in 7 anti-HCV-positive patients and negative in all anti-HCV-negative patients. Fluid HCV RNA was detected in 5 (71.4%) patients testing positive for serum HCV RNA and in none testing negative for serum HCV RNA. Serum HCV genotype was 1a in 3 patients and 1b in 4; PD fluid HCV genotype was 1a in 1 patient and 1b in 4. Genotypes in serum and fluid were concordant when both were positive. Serum viral load ranged from nondetectable by the quantitative method to 5.1 MEq genome/mL in patients with fluid infection, and 1.05 MEq and 29 MEq genome/mL in the remaining 2 patients without detectable HCV in PD fLuid. HCV crosses the peritoneal membrane and may be detected in the dialysate of PD patients with proven viremia. Although our study population was small for firm conclusions to be drawn, this passage does not seem to depend upon the serum viral load. Our data support the notion that PD fluid needs careful handling and local disinfection to prevent possible spreading of viruses, in the institutional and the domestic environments.

Determination of High and Low Molecular Weight Molecules of Icodextrin in Plasma and Dialysate, Using Gel Filtration Chromatography, in Peritoneal Dialysis Patients

The aim of this study was to apply high performance liquid chromatography (HPLC) with modern gel filtration media to determine high molecular weight (HMW) icodextrin fractions and low molecular weight (LMW) icodextrin metabolites in dialysate and plasma in peritoneal dialysis (PD) patients on treatment with icodextrin, and to explore the potential relationships between these compounds, alpha-amylase activity, and glomerular filtration rate. Retrospective study of dialysate and plasma samples from PD patients. Samples were collected at one PD center. Blood and dialysate samples were obtained from PD patients who were subdivided into three groups: patients using only glucose-based peritoneal dialysis fluid (GPDF; GLU group, n = 23), patients studied after the first long dwell with icodextrin-based peritoneal dialysis fluid (IPDF; 1st ICO group, n = 24), and patients who were regular users of IPDF for the long dwells (ICO group, n = 9). LMW icodextrin metabolites [i.e., maltose (G2), maltotriose (G3), maltotetraose (G4), maltopentaose (G5), maltohexaose (G6), and maltoheptaose (G7)] and HMW fractions were determined in plasma and dialysate using two different gel filtration HPLC methods. Enzymatic hydrolysis with amyloglucosidase to glucose yielded the total carbohydrate content and this was used to validate the HPLC results. alpha-Amylase activity was determined using a routine method. The results obtained by gel filtration HPLC yielded values of LMW metabolites and HMW fractions in plasma and dialysate in agreement with results obtained with enzymatic hydrolysis. HMW fractions were not detectable in plasma. Absorption of icodextrin from the peritoneal cavity during the long dwell (10 - 16 hours) was, on average, 39% of the amount instilled. During the long dwell, there was a relative decrease in the dialysate concentration of the largest HMW fractions (>21.4 kDa). Plasma concentration of the LMW icodextrin metabolites G2-G7 was highest in the ICO group (2.65+/-0.54 mg/mL) but also higher in the 1st ICO group (1.97+/-0.57 mg/mL) compared with the GLU group (0.52+/-0.23 mg/mL). Plasma alpha-amylase activity was significantly lower in the 1st ICO group and in the ICO group compared with the GLU group. Accurate analysis of HMW icodextrin fractions in dialysate and LMW icodextrin metabolites in plasma and dialysate in PD patients can be achieved by gel filtration HPLC with two different columns. This method can be used to study the complex pattern of changes in icodextrin and its metabolites in plasma and dialysate. The finding that HMW icodextrin fractions were not detected in plasma was unexpected, and differs from results of previous studies by other researchers.

Improvement of transcellular water transport by treatment with glucose-free dialysate in peritoneal dialysis patients with ultrafiltration failure: M.M. Ho-dac-Pannekeet, D.G. Struijk, R.T. Krediet. Department of Nephrology, Academic Medical Centre, Amsterdam, Netherlands

Improvement of transcellular water transport by treatment with glucose-free dialysate in peritoneal dialysis patients with ultrafiltration failure: M.M. Ho-dac-Pannekeet, D.G. Struijk, R.T. Krediet. Department of Nephrology, Academic Medical Centre, Amsterdam, Netherlands