Miwako Numata

Hyper-Vascular Change and Formation of Advanced Glycation Endproducts in the Peritoneum Caused by Methylglyoxal and the Effect of an Anti-Oxidant, Sodium Sulfite

Objective: Methylglyoxal (MGO) in a heat-sterilized conventional PD solution may damage peritoneal cells directly and/or indirectly by producing advanced glycation endproducts (AGEs). This study was conducted to (a) examine the acute effect of MGO on the peritoneum (including AGE formation) and (b) study the possible AGE suppressive effect of an anti-oxidant, sodium sulfite. Method: (1) Human serum albumin (HAS) was continuously incubated with MGO (50 mM) at 37°C for as long as 14 days and the fluorescence intensity (FI) was determined (em. 440, ex. 370). (2) Three types of test solutions – (i) saline; (ii) MGO (20 mM), and (iii) MGO with sodium sulfite (30 mM) – were administered intraperitoneally to 8-week-old rats once a day for 5 consecutive days. The parietal peritoneum was examined macroscopically on the 6th day for immunostaining of anti-AGE antibodies. Result: (1) An increase in FI of HSA was observed as a function of the incubation period in the MGO solution. (2) Prominent hypervascularity and intense immunostaining of anti-AGE Ab were noted in MGO-treated rats, whereas the macroscopic alterations were suppressed in the rats that had been treated with sodium sulfite. Conclusion: MGO-induced hypervascularity and AGE formation in the peritoneum, as well as macroscopic alterations were suppressed by sodium sulfite. This may indicate that there is a risk of MGO causing a peritoneal injury and that the therapeutic potential of an anti-oxidant for this type of injury may exist.

Relationship Between the −374T/A Receptor of Advanced Glycation End Products Gene Polymorphism and Peritoneal Solute Transport Status at the Initiation of Peritoneal Dialysis

Abstract:  An increased peritoneal solute transport rate (PSTR) at baseline is well known to be associated with decreased patient and technique survival in patients undergoing peritoneal dialysis (PD). Recently, angiogenesis has been recognized to be associated with PSTR and peritoneal deterioration. To investigate genetic variations in genes related to angiogenesis, 30 incident PD patients were studied. Several single nucleotide polymorphisms of the vascular endothelial growth factor (VEGF), the endothelial nitric oxide synthase (eNOS) and the receptor for advanced glycation end product (RAGE) were analyzed by the pyrosequencing method. The dialysate‐to‐plasma ratio of creatinine (D/P Cr) obtained from a peritoneal equilibrium test (PET) during the first 12 months after initiation of PD was used for a marker of PSTR. The D/P Cr was assessed both as a continuous and as a categorical variable including high (H), high‐average (HA), low‐average (LA), and low (L). Baseline D/P Cr was 0.645 ± 0.083. The RAGE −374 TA genotype had a significantly lower prevalence of the H/HA transporters than the TT genotype (20% vs 63%; P = 0.03). Genetic polymorphisms of the VEGF and eNOS were not associated with initial peritoneal transport type. The RAGE polymorphism may have a considerable effect on the basal PSTR. Further studies will be needed to confirm this hypothesis.

Measurement of lean body mass with dual energy X-Ray absorptiometry in dialysis patients and its pitfalls.

Accessible online at: http://BioMedNet.com/karger Dear Sir, A poor nutritional status is significantly related to the high morbidity and mortality rate in patients on regular dialysis treatment [1, 2]. Therefore, an accurate evaluation of the nutritional status in these patients is a matter of clinical importance. So far, among the parameters of the nutritional status, it has been reported that lean body mass (LBM) could well correlate with a better nutritional status [1]. Recently, a whole-body dual-energy X-ray absorptiometry (DXA) has been applied to measure body composition including subjects on dialysis treatment [3–6]. Briefly, a dual-energy X-ray source and the thin X-ray pencil beam scan the entire body. A detector feeds the computer with the absorption and the amount of body composition such as total tissue (TT), total fat mass (TFM), bone mineral content (BMC) and LBM calculated by using the relevant software. In this system, LBM is derived from the following formula: LBM = TT – TFM – BMC. Thus, when determining LBM, the water content is included in its value. Therefore, it is a matter of concern how the hydration state might influence the results of the body composition such as TT and LBM in patients on chronic dialysis treatment. To clarify this question, the following study was performed. Seven patients on hemodialysis (HD; male/female: 6/1, age: 54.1 B 7.2 years, mean B SE) were studied. Measurement of TT, BMC, LBM and TFM were performed by DXA, (Luner-DPX; system-No. 0; Lunder, Madison, Wisc., USA), just before the commencement and immediately after the completion of a regular HD session. Oral intake was stopped during this study. All patients achieved their ideal body weight (euhydrated state) after the removal of excess fluid with HD. Mean fluid removal with HD amounted to 3.1 B 0.9 kg. Changes in each parameter are shown in table 1. No changes were found either in TFM or in BMC. On the other hand, there were significant reductions in TT and LBM after HD. In addition, there was a positive correlation between the changes in TT and LBM (fig. 1). These results show that the fluid content could actually have a significant impact on the measurements of TT and LBM by DXA and these values are decreased in accordance with the fluid removal. It is, therefore, suggested that DXA may overestimate LBM in patients with overhydration. This critical point should be taken into consideration, when applying DXA in clinical settings. Accordingly, in order to assess the nutritional status in patients on HD using DXA, it should be done after achieving the ideal body weight, thus after regular HD. Table 1. Values of each parameter before and after HD

Role of Nitric Oxide in Hypotension during Hemodialysis

Accessible online at: http://BioMedNet.com/karger Dear Sir, Severe hypotension during hemodialysis (HD) is a critical complication which interrupts the HD session. Past reports have demonstrated that, through the neurohormonal system, impaired vasoactive mechanisms are involved in the pathophysiology. Nitric oxide (NO) is one of the important vasodilatory factors which regulate systemic blood pressure (BP), and accumulating evidence suggests the pathophysiological roles of NO in the dysregulation of BP in humans [1–3]. We previously reported that L-arginine, the precursor of NO, could exert a profound depressor effect in patients on chronic dialysis treatment [4]. If NO production is facilitated in patients on HD, this could be one of the factors which induce hypotension during HD. Therefore, in order to examine the possible pathophysiological role of NO in dialysis-related hypotension, we examined the changes in BP and blood levels of NO metabolites during HD. Five patients who showed profound hypotension during dialysis (the Hypo group: male/female ratio 1/4; age 53.6 B 5.5 years old; duration of HD 93 B 40 months) and 9 patients who were not hypotensive (the normal group: male/female ratio 2/7; age 45.9 B 2.8 years old; duration of HD 186 B 16 months) were enrolled in this study. All patients had chronic glomerulonephritis as the underlying renal disease; patients with diabetes, macroangiopathy and cardiac diseases were excluded from this study. They were all normotensive during the inter-dialytic periods, and none were taking antihypertensive medication. They were all hemodialyzed for 4–5 h with QB 200 ml/min three times a week, using hollow-fiber dialyzers (membrane materials: cuproammonium layon; hemophan, and polysulfone) with continuous infusion of heparin (500–750 IU/h). In these patients, blood samples were collected before and after the dialysis, and BP before dialysis and the lowest BP during the dialysis session were recorded. The levels of blood NO metabolites (NOx) were measured according to the Griess technique, after complete reduction of NO3 to NO – 2 by the Cucoated cadmium method [5]. The mean BP (MBP) was calculated from the following formula: MBP (mm Hg) = D + [S – D)/3], where D = diastolic pressure and S = systolic pressure. Results are presented as the mean B SE. The significance was analyzed by MannWhitney U test. The changes in BP of the respective groups were as follows: the MBP before the dialysis was 95.4 B 4.0 mm Hg (Hypo group) vs. 100.8 B 2.0 mm Hg (normal group, NS): the lowest MBP during the dialysis was 53.6 B 4.2 mm Hg (Hypo group) vs. 87.1 B 2.9 mm Hg (normal group, p ! 0.001). No differences were found in the reduction in body weight during dialysis beTable 1. The NOx levels in the respective patients

Facilitated IL-1β Production from Mononuclear Cells in Peritoneal Dialysate – Ex vivo Study

Accessible online at: http://BioMedNet.com/karger Dear Sir, Interleukin-1ß (IL-1ß) is one of the inflammatory cytokines which is released from cells such as mononuclear cell, monocyte (MC) and macrophage (MØ). In CAPD it is well known that the concentration of IL-1ß in the PD effluent is increased during bacterial peritonitis. However, recent studies have reported that some inflammatory cytokines such as IL-1ß are detectable in the effluent, even without peritonitis [1]. In the case without peritonitis, IL-1ß in the PD effluent may be coming from the circulating plasma by way of diffusion and/or convection force during CAPD treatment. However, the exact origin of IL-1ß in the effluent has not been clarified in these cases. On the other hand, a large number of cells are found in the effluent even without peritonitis, and the predominant cell types isolated from the effluent are MC and MØ [2]. Accordingly, it might be possible that those MC/MØ in the peritoneal cavity release IL-1ß even without peritonitis. This study was performed to test this hypothesis. Five patients on stable CAPD without peritonitis were studied (4 males/1 female; mean age 57.2 B 11.3 years; primary renal disease: chronic glomerulonephritis/nephrosclerosis: 4/1; duration of CAPD 1–22 months). All patients had been exchanging standard PD solution (Dianeal PD-4®, Baxter Japan). In these patients PD effluent which had been dwelled for more than 6 h was obtained in the iced Dianeal bag. Each effluent was centrifuged (450 g, 15 min) and thereafter cell fraction was washed twice with Roswell Park Memorial Institute (RPMI) 1640 medium. Cells (5 ! 105) were incubated in the culture medium (0.5 ml DMEM + 10% FBS) for 24 h at 37°C. The level of IL-1ß in the supernatant was measured using a commercially available ELISA kit (R & D Systems, USA). The viability of obtained cells was always above 95% as judged by trypan blue exclusion. In respective patients, peripheral blood was withdrawn at the same time in order to obtain peripheral blood mononuclear cells (PBMC). This was layered onto Ficoll-metrizoate medium (Sigma, St. Louis, Mo., USA). Thereafter, it was centrifuged (450 g, 15 min) and the cell fraction was washed twice with RPMI 1640 medium. Cells (5 ! 105) were incubated, and the measurement of supernatant IL-1ß concentration was performed in the same fashion as the peritoneal cells. The IL-1ß concentration in the respective supernatant of incubated MC/MØ is shown in table 1. IL-1ß was not detected in the supernatant of the peripheral blood MC/ MØ, whereas it was detected in the supernatant of the cells of PD effluent in 3 of 5 cases. The IL-1ß concentration in the respective supernatant of incubated MC/MØ with or without lipopolysaccharide (LPS) is shown in table 2. A stimulation of LPS revealed different reactions of MC/MØ. A concentration of IL-1ß in the supernatant of peripheral