[Influence of different pharmacological agents in the ex vivo proliferation of mesothelial cells obtained from the peritoneal effluent of patients treated with peritoneal dialysis]

Mesothelial cells (MC) are the first peritoneal membrane barrier in contact with dialysate. The aim of this study was to analyze the in vitro capacity of different pharmacological agents to modify the ex vivo proliferation of MC obtained from the peritoneal effluent of patients treated with peritoneal dialysis (PD).

MATERIAL AND METHODS

Thirty cultures of MC taken from nocturnal peritoneal effluent were performed. After identification, MC are subcultured in 24 multi-well plates, adding the different exogenous agents. Proliferative capacity and cell morphology were estimated on day 16th of culture. The agents evaluated were insulin, IGF-1, tamoxifen, labetalol, carvedilol, enalapril and losartan.

RESULTS

Insulin shows a dose-dependent effect on MC growth, with a limit that is stimulated by the addition of fetal bovine serum (FBS). Concentrations higher than 100 micrograms/ml, are not associated with further growth, even with cell damage. In contrast, the wide range of IGF-1 dose used did not affect to MC proliferation. Tamoxifen causes negative effects on MC growth just a very high doses, not resembling doses in clinical practice. Labetalol does not modify MC proliferation used under therapeutic calculated range. However, concentrations higher than 40 micrograms/ml showed a negative influence on growth, behaving as lethal doses that over 100 micrograms/ml. The addition of FBS attenuates this effect. These effects were very similar to that caused by carvedilol addition. Enalapril and losartan act as antiproliferative agents for MC. This effect is potentiated with angiotensin II, reaching lethal concentrations increasing the dose. In conclusion, mesothelial cell growth ex vivo taken from nocturnal peritoneal effluent on PD patients is an useful tool to explore the effects of any pharmacological agent on the biology of the cell of the peritoneum. The agents used had any influence in the proliferation capacity of mesothelial cells.

Malnutrition-inflammation syndrome is associated with endothelial dysfunction in peritoneal dialysis patients

Endothelial dysfunction with atherosclerosis is a recognized complication of uremic patients. The hypoalbuminemia of peritoneal dialysis (PD) patients can induce a hypercoagulable and atherogenic state. In this study, we investigated the role played by malnutrition-inflammation syndrome on endothelial function markers in PD patients. We measured markers of nutrition [normalized protein catabolic rate (nPCR), albumin, prealbumin, insulin-like growth factor 1 (IGF-1), transferrin, and cholesterol], markers of endothelial damage and function [tissue-type plasminogen activator (tPA), thrombomodulin (TM), von Willebrand factor (vWF), and NO3 (representing NO)], markers of a coagulable state [fibrinogen and plasminogen activator inhibitor 1 (PAI-1)], markers of inflammation [tumor necrosis factor alpha (TNF alpha) and C-reactive protein (CRP)], and other endothelial injury factors [lipoprotein(a) [Lp(a)] and homocysteine]. We also performed an endothelial stimulation test consisting of right-arm venous occlusion (VO) for 10 minutes. The patients were divided into four groups according to their clinical atherosclerotic score (CAS). We studied 45 clinically stable PD patients. At baseline, statistically significant negative linear correlations were found between albumin and age (r = -0.54, p < 0.05), albumin and vWF post-VO (r = -0.54, p < 0.05), and albumin and TM (r = -0.36, p < 0.05), which are endothelial damage markers and prothrombotic factors. A positive linear correlation was seen between albumin and NO3 post-VO (r = 0.48, p < 0.05), indicating a high vasodilatation capacity. C-Reactive protein and TNF alpha showed a positive linear correlation (r = 0.5, p < 0.01). Similarly, TNF alpha showed a positive linear correlation with cardiovascular risk markers such as fibrinogen (r = 0.79, p < 0.01), PAI-1 (r = 0.44, p < 0.05), and homocysteine (r = 0.37, p < 0.05). Creatinine clearance showed a negative linear correlation with TM (r = -0.36, p < 0.05). Patients with albumin < 4 g/dL showed a lower tPA ratio, lower NO3, and a higher CRP, TNF alpha, and Lp(a) than did patients with albumin > 4 g/dL [tPA ratio: 2.1 +/- 1.56 (n = 29) vs. 2.6 +/- 2.3 (n = 16), p < 0.05; NO3: 47 +/- 27 micrograms/mL vs. 69 +/- 33 micrograms/mL, p < 0.05; CRP: 1.8 +/- 3 mg/dL vs. 1.1 +/- 1.6 mg/dL, p < 0.05; TNF alpha: 44.4 +/- 16 pg/mL vs. 36.6 +/- 21.4 pg/mL, p < 0.05; Lp(a): 55 +/- 39 mg/dL vs. 33 +/- 21 mg/dL, p < 0.05]. Patients with a worse CAS showed higher homocysteine levels and lower albumin values. Those relationships were maintained in both periods of the study. We found no relationships between dialysis dose and endothelial function markers. In conclusion, malnutrition-inflammation syndrome may contribute to endothelial dysfunction and, consequently, to prothrombotic and proatherogenic processes in PD patients.

Comparisons of hemodialysis and CAPD in patients over 65 years of age: a meta-analysis

This meta-analysis had the aim of studying the available studies on comparison between Hemodialysis and Peritoneal Dialysis in the elderly. The final objective was to reach, if possible, evidence for potential differences. In the case that no differences could be demonstrated, contribute to accept that HD and PD are similar techniques to be offered to elderly people requiring dialysis. The question formulated was this: Do we have adequately contrasted data on results for survival, hospitalization rate, quality of life and morbidity on hemodialysis and peritoneal dialysis in the elderly (more than 65 years old)? As data sources we selected eight papers that compared the general results of these two dialysis techniques. Different elements were considered in this selection because none reached the two first levels in the hierarchy of sources of evidence, and only two reached the third level--that of prospective studies; this is because an oral presentation of data has been included in a meta-analysis. Another four papers--uni- or multicenter retrospective studies compared the results obtained with PD and HD. The remaining two papers--reports from nationwide registries that compare of mortality rates, adjusted for co-morbid conditions and age, present specific results on groups of elderly patients. Three papers compare particular aspects of the two techniques, including nutritional status, psychiatric and psychosocial aspects and rehabilitation, in this case comparing PD with home hemodialysis patients. Finally, we have included the opinions of healthy elderly people on dialysis issues. This meta-analysis of these different studies suggests that the mortality and hospitalization rate of elderly people treated by PD is similar to that of similar people treated by HD. In consequence, we have no reasons to select either therapy on behalf of the patient. The nephrologist should consider and inform the patient and family about the relative advantages and disadvantages of both techniques and tailor dialysis technique choice to the specific individual to assure the best results. Local circumstances should also be considered.

[Use of icodextrin for diurnal exchange in patients undergoing automatic peritoneal dialysis. Comparison with glucose solutions]

Icodextrin (IC) is an osmotic agent that produces sustained ultrafiltration (UF) during long dwell time periods in peritoneal dialysis patients. The aim of this study was to evaluate the effects of 7.5% IC for the diurnal exchange in automated peritoneal dialysis (APD) patients and to compare them with that of 2.27% glucose solutions. Seventeen patients treated on APD during 13.9 +/- 12.7 months were included. The study was divided into three eight weeks phases. During the baseline period patients used 2.27% glucose for the daytime, second, IC 7.5% was prescribed for the day-exchange, and finally 2.27% glucose solution was used for the last eight weeks. Daytime UF increased in all patients during IC use (-53 +/- 22 to 270 +/- 304 ml/day, p < 0.01). Patients with higher peritoneal permeability capacity obtained more benefits. Daytime urea KT/V and weekly creatinine clearance (WCC) augmented significantly during IC use, but the increase of weekly urea KT/V and WCC was not significant (2.18 +/- 0.45 to 2.26 +/- 0.41 and 62.7 +/- 18 to 66.6 +/- 15 l/week/1.73 m2; respectively). On IC, nightly glucose load significantly decreased (289 +/- 82 to 266 +/- 94 g, p < 0.05), returning to previous value after withdrawal. Plasma osmolality did not change, although plasma sodium levels decreased during IC use (140 +/- 3 to 136 +/- 2, p < 0.001). Serum amylase levels significantly declined during IC use (279 +/- 151 to 29 +/- 9 U/l), returning to previous values after transfer to glucose. Peritoneal function transport parameters and peritoneal protein losses did not change. IC metabolite plasma levels increased during the use of this solution, returning to previous values after withdrawal. In conclusion, IC dialysate is an excellent alternative to glucose dialysate for the day-exchange in APD patients. Daytime UF increased in all patients, but those with higher peritoneal permeability capacity obtained more benefits. The decrease of the glucose peritoneal load overnight and the reduction for more than 50% of exposure time of the peritoneal membrane to glucose solutions, probably make IC solution a more biocompatible fluid.

Helicobacter pylori infection: a new cause of anorexia in peritoneal dialysis patients

OBJECTIVE

Helicobacter pylori (HP) infection has frequently been found in dialysis patients. Chronic infections induce overproduction of pro-inflammatory substances. Inflammation has been associated with cachexia and anorexia. We explored the relationship between HP infection, anorexia, and malnutrition in peritoneal dialysis (PD) patients.

PATIENTS AND METHODS

The study included 48 clinically stable PD patients divided into four groups: HP+ with anorexia (group I, n = 12); HP+ without anorexia (group II, n = 4); HP- with anorexia (group III, n = 5); and HP- without anorexia (group IV, n = 27). Infection with HP was diagnosed by breath test. Anorexia was evaluated using a personal interview and an eating motivation scale (VAS). The VAS included five questions that are answered before and after eating. The questions concern desire to eat, hunger, feeling of fullness, prospective consumption, and palatability. Biochemical markers of nutrition and inflammation were also determined.

RESULTS

At baseline, group I showed lower scores for desire to eat, hunger sensation, prospective consumption, and palatability. They also showed lower lymphocyte counts, prealbumin, transferrin, serum albumin, normalized equivalent of protein-nitrogen appearance (nPNA), and residual renal function (RRF). In addition, the same group showed higher levels of C-reactive protein (CRP) and more sensation of fullness than the remaining groups. In the entire series, we found significant linear correlations between the following markers of nutrition and certain questions on the VAS: albumin with before-lunch desire to eat (r = 0.38, p < 0.05), and prealbumin with before-lunch hunger (r = 0.41, p < 0.05) and after-lunch hunger (r = -0.35, p < 0.05). Negative linear correlations were found between albumin and fullness before lunch (r = -0.45, p < 0.01), and between prealbumin and before-lunch desire to eat (r = -0.39, p < 0.05). Negative linear correlations were also seen between CRP and albumin (r = -0.35, p < 0.05) and between CRP and prealbumin (r = -0.36, p < 0.05). Similarly, CRP showed a negative correlation with before-lunch desire to eat (r = -0.38, p < 0.05) and afterlunch desire to eat (r = -0.45, p < 0.01). After HP eradication, group I showed a significant increase in markers of nutrition and in VAS scores for almost all questions. Simultaneously, they showed a decrease in CRP level. Significant differences were also found in lymphocyte count (1105 +/- 259.4 cells/mm3 vs 1330.8 +/- 316 cells/mm3, p < 0.05), nPNA (0.9 +/- 0.16 g/kg/day vs 1.07 +/- 0.3 g/kg/day, p < 0.05), prealbumin (26.7 +/- 6.5 mg/dL vs 33.9 +/- 56.6 mg/dL, p < 0.01), albumin (3.48 +/- 0.3 g/dL vs 3.67 +/- 0.35 g/dL, p < 0.05), CRP (1.16 +/- 1.14 mg/dL vs 0.88 +/- 1.2 mg/dL, p < 0.054), before-lunch desire to eat (56.6 +/- 6.8 vs 72.2 +/- 4, p < 0.001), after-lunch desire to eat (5.4 +/- 2.6 vs 12.3 +/- 2, p < 0.01), hunger before lunch (55.4 +/- 5.4 vs 73.1 +/- 4.6, p < 0.001), hunger after lunch (5.8 +/- 2.9 vs 11 +/- 4, p < 0.01), fullness before lunch (36.6 +/- 10.3 vs 18.7 +/- 8.8, p < 0.001), consumption after lunch (5 +/- 4.7 vs 17.5 +/- 18, p < 0.05), and palatability (61 +/- 5.3 vs 74.1 +/- 4.1, p < 0.001).

CONCLUSION

Infection with HP is associated with anorexia, inflammation, and malnutrition in PD patients. Eradication of HP significantly improves this syndrome. Residual renal function seem to have a protective effect on appetite preservation. The present study supports the hypothesis of the involvement of inflammation in the pathogenesis of malnutrition in PD patients.

Effect of bicarbonate/lactate peritoneal dialysis solutions on human mesothelial cell proliferation ex vivo

Peritoneal membrane suffers structural and functional changes over time on peritoneal dialysis (PD)--in part, owing to the dialysis solutions currently used. Low pH seems to be an important element associated with solution bioincompatibility. Bicarbonate-containing fluids open new perspectives on this issue. The present study compared the effects of bicarbonate/lactate (Bic/Lac) solution (25 mmol/L bicarbonate, 15 mmol/L lactate) and lactate (Lac) solution (40 mmol/L lactate) on mesothelial cell (MC) growth in culture. Eight stable PD patients were asked to collect peritoneal effluent from an 8-hour dwell on two separate days, within an interval shorter than one week. For the first dwell, Lac solution was infused; for the second dwell, Bic/Lac solution was instilled. Human MCs were isolated from the effluent, seeded in 25-cm2 tissue culture flasks, and grown ex vivo. Morphology of the cells was also evaluated. In all effluents, MCs were present in mean amounts of 26,939 +/- 21,267 cells (Bic/Lac) and 25,986 +/- 15,286 cells [Lac, p = nonsignificant (NS)]. Morphology of the MCs was similar with both solutions (87.5% typical). After initial culture, MCs from 6 patients using Bic/Lac (75%) and 3 patients using Lac (37.5%) reached confluence. At this time, the number of MCs from the 3 patients who showed MC growth with both solutions was slightly higher with Bic/Lac-buffered fluid (Lac: 1,154,125 +/- 213,333 cells; Bic/Lac: 1,198,291 +/- 806,713 cells). To summarize: 3 patients showed MC growth under both solutions; 3 patients showed MC growth only under Bic/Lac solution; and 2 patients showed no MC growth at all. After cells were seeded in 24-well plates, the MC growth curve was performed in 4 cases of Bic/Lac solution use and in 3 cases of Lac solution use. Although no significant differences were observed between the solutions, the final number of MCs obtained was higher with Bic/Lac solution use. In conclusion, MCs released into peritoneal effluent under bicarbonate/lactate-buffered peritoneal dialysis solution are associated with a greater ex vivo proliferation capacity than those released under lactate solution in the same patient. This finding may demonstrate better biocompatibility for Bic/Lac solution.

Alpha replacement method for displaced peritoneal catheter: a simple and effective maneuver

Displacement of the peritoneal catheter tip is one of the most frequent causes of catheter malfunction. As a consequence, appropriate peritoneal effluent drainage is impossible. Alternatives to catheter exchange or invasive abdominal intervention did not appear until the alpha maneuver was described by Yoshihara et al. We review our experience with this maneuver over the last 7 years. We used the alpha maneuver in 24 peritoneal dialysis (PD) patients (13 men and 11 women) with a mean age of 52 +/- 16 years. Some patients required several repeat procedures (total procedures: 32). The mean time between placement of the catheter and performance of the alpha maneuver was 6.5 +/- 7.9 months. In all patients, the technique was indicated for problems with peritoneal effluent drainage, after verification of catheter tip displacement by radiologic examination. In 6 patients, the initial maneuver was unsuccessful and had to be repeated. The first maneuver was effective in 11 of 24 cases (46%) and unsuccessful in the other 13 (54%). No differences in sex, renal disease, or age were seen between the two groups. The mean time between catheter placement and tip displacement detection was significantly lower in the cases of ineffective maneuver (2.7 +/- 4.3 months) than in those that met with success (10.8 +/- 9 months). In other words, 84% of unsuccessful maneuvers were performed in the first 3 months of catheter life. Of the 11 patients successfully treated, 6 continued on PD for 14.7 +/- 6.3 months. Two other patients were transplanted with normal-functioning catheters, and two more left PD (after 10 and 17 months) for reasons unrelated to the catheter. One patient required a catheter change owing to breakdown in the Silastic after disruption by the metallic guide, which perforated the catheter wall. The 13 ineffective maneuvers involved 7 omentum entrapments, 1 procedure that was repeated effectively 15 days later, and 5 definite failures requiring catheter change. The failure rate may therefore be considered to be 20.8%, taking into consideration that omentum entrapment should not be an indication for the procedure. We conclude that the alpha maneuver for a displaced peritoneal catheter is a simple and effective procedure that can be applied at the patient's bedside. In consequence, it should be the technique of first choice in these situations. Only when the alpha maneuver fails should invasive methods, including catheter change, be considered.

Anorexia in end-stage renal disease: pathophysiology and treatment

Anorexia is a frequent complication of uraemic syndrome, which contributes to malnutrition in dialysis patients. Uraemic anorexia has been associated with many factors. This paper reviews the current knowledge about mechanisms responsible for uraemic anorexia, the treatments and new drugs used to control the loss of appetite. Traditionally, anorexia in dialysis patients has been considered as a sign of uraemic toxicity, therefore, two hypotheses have been proposed, the 'middle molecule' and 'peak-concentration' hypotheses, both of which are still unproved. Recently, our group proposed the tryptophan-serotonin hypothesis, which is based on a disorder in the amino acid profile acquired in the uraemic status. This is characterised by low concentrations of large neutral and branched chain amino acids (LNAA/BCAA) in the cerebrospinal fluid. This situation permits a high level of tryptophan transport across the blood-brain barrier, causing an increase in the synthesis of serotonin (responsible for appetite inhibition). There are two main treatment targets for anorexia in dialysis patients. The first is to decrease the free plasma tryptophan concentration and transport across the blood brain barrier to the cerebrospinal fluid, thus decreasing the intracerebral serotonin levels. Nutritional formulae enriched with LNAA and BCAA have this effect. Secondly, plasma levels of cytokines with cachectin effect (TNF-alpha), should be decreased. This also induces a decrease in LNAA and BCAA levels. In this group are megestrol acetate, anti-TNF-alpha antibodies, thalidomide, pentoxifyilline, n-3 fatty acids and possibly nandrolone decanoate. Additionally, other targets should be explored including antagonists of cholecystokinin (a potent anorexigen retained by renal failure), analogues of neuropeptide Y (the most potent orexigen), cannabinoids, cyproheptadine, hydrazine sulfate. In conclusion, uraemic anorexia is a complex complication associated with malnutrition, high morbidity and mortality. The pharmacological treatment should address key points in the pathogenesis of uraemic anorexia, reducing intra-cerebral concentration of serotonin with LNAA/BCAA oral diet formulae and the plasma levels of pro-inflammatory molecules. Others forms of treatment should also be explored.

Diverticular disease and treatment with gastric acid inhibitors do not predispose to peritonitis of enteric origin in peritoneal dialysis patients

OBJECTIVE

Enteric peritonitis (EP) is an infrequent complication of peritoneal dialysis (PD), with severe consequences for peritoneal membrane viability and patient outcome. Factors such as diverticular disease and gastric acid inhibitors have been implicated in its appearance. We investigated several risk factors, including those mentioned below, that can influence the development of EP.

DESIGN

Retrospective cross-sectional study.

SETTING

Tertiary-care public university hospital.

PATIENTS

Fifty-seven PD patients treated in our PD unit during August 1998.

MAIN OUTCOME MEASURES

A barium enema was performed on 50 of the 57 patients (the remaining 7 patients refused it) in order to exclude the presence of diverticulosis. All episodes of peritonitis occurring in those patients, including EP, were registered. Enteric peritonitis was defined as that caused by gram-positive, gram-negative, or fungus micro-organisms that colonized the intestinal tract, excluding episodes secondary to genitourinary tract or peritoneal catheter exit-site infections.

RESULTS

Twenty-four patients showed diverticular disease in the barium enema, but only 5 of them (21%) had any EP episode. Five of the 26 patients with no diverticula (19%) had EP. Fifty-five episodes of peritonitis were reported in 21 patients; 15 episodes of EP (27.3% of all) developed in 11 patients. Seven of the 11 patients (64%) required peritoneal catheter removal and 3 of them (27%) finally were transferred to hemodialysis due to consequences of the EP episode. Logistic regression analysis did not find any of the independent variables analyzed (age, sex, time on PD, type of PD, peritoneal transport parameters, presence of polycystic kidney disease, constipation or diverticulosis, or treatment with gastric acid inhibitors, or phosphate-binding agents) to be risk factors for developing EP.

CONCLUSIONS

Neither diverticulosis nor treatment with gastric acid inhibitors seem to be risk factors for developing peritonitis of enteric origin in PD patients. This type of peritonitis has to be promptly identified and treated in order to diminish the high frequency of peritoneal catheter removal and PD dropout due to such episodes.

Vascular endothelial growth factor (VEGF) levels in peritoneal dialysis effluent

BACKGROUND

Long-term peritoneal dialysis (PD) patients who develop peritoneal ultrafiltration failure have an abnormally large number of capillaries and sclerotic changes in peritoneal biopsy. Peritoneal vascular endothelial growth factor (VEGF) production has been suggested to explain the higher levels in peritoneal effluent than in plasma. The high effluent VEGF levels have been related to peritoneal changes consisting of increased permeability to small molecules. To further analyze the relationship between peritoneal neoangiogenesis induced by VEGF and peritoneal transport, we studied peritoneal effluent VEGF levels in active PD patients.

METHODS

VEGF levels were determined in serum and plasma, and in peritoneal effluent (PE) after 4, 8 and 15 h dwell times.

RESULTS

PE VEGF levels were 58.6+/-33.7 pg/mL, with a mean VEGF D/P ratio of 0.45+/-0.29 (range 0.06-0.93). In low-transport patients (n = 7) this ratio did not differ from high-average ones (n=5) (0.48+/-0.3 and 0.41+/-0.1, NS). In multivariate analysis, the VEGF D/P ratio showed no correlation with the independent variables included in this study. VEGF levels were higher in 15 h than in 8 h effluent; so the VEGF D/P ratios were higher as well. Regression analysis showed a direct correlation between PEVEGF levels and dwell time (r: 0.57, p = 0.03), but not between VEGF D/P ratio and dwell time. PEVEGF levels directly correlated with effluent protein content. Regression analysis showed no correlation between PEVEGF levels and age, time on PD, days of peritonitis, urea and creatinine-mass transfer coefficients, ultrafiltration capacity, and accumulated glucose dose. Multivariate regression analysis showed correlation only between PEVEGF levels and dwell time, but not with the other independent variables.

CONCLUSIONS

This study confirms that VEGF is present in fresh PE from PD patients at levels that suggest local production and filtration from plasma. Peritoneal effluent VEGF levels are not significantly associated with peritoneal functional parameters and background, and seem to be influenced by ultrafiltration in a dilution process. We believe that the role of VEGF in peritoneal pathophysiology is part of a complex relationship involving multiple peritoneal structures and other growth factors, including local counteracting factors for VEGF that regulate neoangiogenesis.

Peritoneal dialysis is the therapy of choice for end-stage renal disease patients with hereditary clotting disorders

Chronic renal failure is an unusual complication of hereditary clotting disorders (HCDs), but this situation could change in the near future. The modality of dialysis for end-stage renal disease (ESRD) in patients with an HCD is a difficult choice. Hemodialysis (HD) may be considered, but intensive treatment with coagulation factors is required for vascular access execution and for each HD procedure. Peritoneal dialysis (PD) has been infrequently proposed. However, PD requires coagulation replacement therapy only during peritoneal catheter placement. The aim of this paper is to describe our experience of three patients with ESRD and HCD, successfully treated with chronic PD in the medium term. Case 1 was a 58-year-old man with moderate hemophilia A, type 2 diabetes mellitus, and hepatitis C virus (HCV) infection. His ESRD was secondary to glomerulonephritis. A double-cuff peritoneal catheter was surgically placed with pre-emptive factor VIII administration. He began treatment with continuous ambulatory peritoneal dialysis (CAPD). An inguinal hernia was repaired without complications. After eleven months of follow-up, no hemorrhage episodes have been observed and clinical outcome is optimal. Case 2 was a 46-year-old man with severe hemophilia A, type 2 diabetes mellitus, and HCV and human immunodeficiency virus (HIV) infections. He developed a diabetic nephropathy that required renal replacement therapy. A permanent silicone catheter was inserted in the left internal jugular vein, and the patient started HD treatment. Later on, PD therapy was proposed. A peritoneal catheter was implanted with simultaneous factor VIII infusion. Minimal bleeding was observed at the subcutaneous tunnel over the following 48 hours. The patient started PD treatment without complications, and two months later, remaining asymptomatic, transferred to another center. Case 3 was a 41-year-old woman diagnosed with von Willebrand disease type 2A, HCV infection, and polycystic kidney disease, who presented with ESRD. An internal arteriovenous fistula was performed under coagulation factor cover. During a fistulography, and despite coagulation factor substitutive treatment, the patient showed an important hematoma. Afterwards, PD was considered. A peritoneal catheter was implanted under coagulation factor cover. The postoperative course was uncomplicated, and the patient started CAPD treatment. During follow up, she suffered two hemoperitoneum episodes that were resolved with cold dialysate. After nine months, she uneventfully continued on PD. In conclusion, PD is the therapy of choice for patients with hereditary clotting disorders and ESRD requiring dialysis. Peritoneal dialysis therapy avoids many of the complications related to HD therapy.

Serum level of vascular endothelial growth factor is influenced by erythropoietin treatment in peritoneal dialysis patients. (Grupo de Estudios Peritoneales de Madrid)

Some patients on long-term peritoneal dialysis (PD) develop a hyperpermeability state, owing to peritoneal neoangiogenesis. Vascular endothelial growth factor (VEGF), a potent mitogen for endothelial cells, has been implicated in most diseases characterized by microvascular neoformation. Erythropoietin (EPO) is able to induce endothelial proliferation in vitro. Our aim was to elucidate whether VEGF serum levels are influenced by EPO treatment, and whether VEGF serum level maintains a relationship with peritoneal transport data. We analyzed serum levels of VEGF in 35 PD patients (18 males, 17 females). Mean age was 58 years, with a mean time on PD of 98 +/- 75 months. Of the 35 patients, 19 were on automated peritoneal dialysis, and 16 were on continuous ambulatory peritoneal dialysis. Seven patients had diabetes. Peritoneal transport parameters were: urea mass transfer coefficient (MTC), 19.5 +/- 6.6 mL/min; creatinine MTC, 9.9 +/- 4.7 mL/min; net ultrafiltration, 491 +/- 166 mL per 4-hour dwell. Twenty seven patients were under therapy with recombinant human erythropoietin (rHuEPO). Mean serum VEGF levels were 347 +/- 203 pg/mL (range 66-857 pg/mL), with most patients in the normal range (60-700 pg/mL). VEGF levels did not correlate with age, sex, primary renal disease, diabetes, type of PD, time on PD, peritonitis, and cumulative glucose load. We found no correlation with urea MTC, creatinine MTC, ultrafiltration rate, or protein effluent levels. However, a significant negative correlation with residual renal function was seen (r = -0.39, p < 0.05). Patients treated with rHuEPO showed significantly higher serum levels of VEGF than non treated patients (375 +/- 220 pg/mL vs 251 +/- 75 pg/mL, p < 0.05), although they had similar residual renal function. We conclude that increased serum VEGF levels are associated with EPO treatment. Consequently, VEGF might have a role in the EPO effects found in PD patients. Whether both agents are related to peritoneal neoangiogenesis requires further research.

Cultures of human osteoblastic cells from dialysis patients: influence of bone turnover rate on in vitro selection of interleukin-6 and osteoblastic cell makers

The factors contributing to renal osteodystrophy are still incompletely characterized. A variety of cytokines and growth factors appear to have ill-defined roles in this disease. Our aim is to compare osteoblastic cell growth and different osteoblastic markers in vitro with histomorphometric bone parameters and some serum bone-turnover markers in vivo in dialysis patients with either high- (HTBD) or low-turnover (LTBD) bone disease. Six patients were diagnosed to have LTBD, and another five patients, HTBD. Intact parathyroid hormone (PTH) and osteocalcin (OC) levels in serum were greater in patients with HTBD than in those with LTBD. Osteoblastic cells isolated from iliac crest biopsy specimens were grown in culture medium for different times up to 13 days. Osteoblastic cell growth (cell number and area under the cell growth curve) was greater in patients with HTBD than in those with LTBD. Static and dynamic bone formation parameters correlated with serum PTH levels. No correlation was found between PTH and osteoblastic cell proliferation. OC, C-terminal type I procollagen, and alkaline phosphatase osteoblastic secretion in vitro were similar in the HTBD and LTBD groups. However, interleukin-6 (IL-6) secretion was greater in cells isolated from patients with LTBD. Our results indicate that osteoblastic cell growth and osteoblastic IL-6 secretion are related to bone turnover in patients with osteodystrophy. Our findings support the hypothesis that factors other than PTH level might have an important role in affecting osteoblastic function in renal osteodystrophy.

Icodextrin effluent leads to a greater proliferation than glucose effluent of human mesothelial cells studied ex vivo

OBJECTIVE

To compare the effect of glucose (Glu) and icodextrin (Ico) dialysate on in vitro culture of mesothelial cells (MC) from peritoneal dialysis (PD) patients.

DESIGN

Prospective, controlled comparative study on the effects of two PD solutions.

SETTING

A tertiary-care public university hospital.

PATIENTS

Sixteen PD patients regularly using Glu dialysate were asked to collect an 8-hour dwell peritoneal effluent on 2 different days, with an interval shorter than 7 days. In the first collection, 2.27% Glu solution and in the last, 7.5% Ico solution was infused. Human MC were isolated from the nocturnal peritoneal effluent bags and grown ex vivo.

MAIN OUTCOME MEASURES

Mesothelial cell proliferative capacity ex vivo.

RESULTS

Mesothelial cells were present in all patient dialysates except that of a single patient's Glu dialysate. The number of MC drained was similar with both solutions. After the initial culture reached confluence, MC were identified in 14 and 12 patients receiving Ico and Glu, respectively. However, in 1 patient using Ico and in 2 using Glu, the MC count at this stage was so low that further subculture could not be performed. Cells from Ico-derived solutions exhibited a higher degree of proliferation than cells from Glu-derived solutions. The morphology of MC was also different. Cells from drained effluent were typical in 11 patients using Glu solution in contrast with 14 patients using Ico. At confluence, the percentages of typical appearance were 50% and 92.9% (p < 0.05) in Glu and Ico respectively.

CONCLUSIONS

Mesothelial cells taken from icodextrin effluent show a greater proliferation ex vivo than those taken from glucose effluent.

Cholinergic modulation of growth hormone responses to growth hormone-releasing hormone in uraemic patients on peritoneal dialysis

BACKGROUND

Hypothalamic cholinergic neurotransmission plays a major role in the regulation of GH secretion. Pyridostigmine, a cholinesterase inhibitor, is able to decrease hypothalamic somatostatinergic tone and release GH in normal subjects. Blockade of muscarinic receptor with pirenzepine blunts the GH release in several clinical situations. However, little information is available on the role played by central cholinergic pathways in GH regulation in uraemic patients.

OBJECTIVE

We aimed to assess GH responses to GHRH after pretreatment with pyridostigmine and pirenzepine in a group of uraemic patients undergoing peritoneal dialysis (PD). GH responses of the patients treated with recombinant human erythropeitin (rhEPO) were compared to patients without treatment.

DESIGN

We studied 14 male patients on PD and nine control subjects. All subjects underwent three endocrine test in random order after an overnight fast. Each subject received GHRH (100 microg, i.v. in bolus at 0 minutes). Sixty minutes before the injection of GHRH subjects were given oral placebo, pyridostigmine (120 mg), or pirenzepine (100 mg).

MEASUREMENTS

Blood samples for GH were collected at -60, 0, 15, 30, 45, 60 and 90 minutes The hormonal secretory responses were studied by a time-averaged (area under the curves, AUC) and time-independent (peak values) analysis.

RESULTS

Baseline GH concentrations were similar in patients and controls. GH responses to placebo plus GHRH were also comparable in patients and controls (peak 26.6 +/- 3.8 vs. 33.2 +/- 4.4 mU/l, AUC 28.2 +/- 3.4 vs. 27.8 +/- 4.6 mU/h/l). Pyridostigmine administration induced a significant potentiation of GH responses to GHRH both in patients (peak 43.2 +/- 5.2 mU/l, AUC 47.6 +/- 6.0 mU/h/l; P < 0.01) and in control subjects (peak 79.2 +/- 8.6 mU/l, AUC 78.0 +/- 9.4 mU/h/l; P < 0.01). However, the increment in GH peak and AUC was significantly (P < 0.05) greater in controls in relation to values found in patients. Pirenzepine administration induced an abolishment of GH release after GHRH stimulation both in PD patients (peak 5.4 +/- 2.6 mU/l, AUC 6.0 +/- 2.4 mU/h/l; P < 0.01) and in healthy controls (peak 3.8 +/- 0.6 mU/l, AUC 4.0 +/- 0.4 mU/h/l; P < 0.05). Responses to pyridostigmine plus GHRH and pirenzepine plus GHRH were similar in patients on chronic therapy with recombinant human erythropeitin and in patients without rhEPO therapy.

CONCLUSION

These results suggest that the cholinergic regulation of GH release is preserved in uraemic patients on peritoneal dialysis. The significantly lower increase in GH response to GHRH induced by pyridostigmine suggests that cholinergic stimulatory tone is attenuated in patients in relation to control subjects. Long-term therapy with rhEPO seems not to affect GH responses to cholinergic stimulation or blockade.

Risk factors responsible for ultrafiltration failure in early stages of peritoneal dialysis

OBJECTIVE

To define risk factors for ultrafiltration failure (UFF) during early stages of peritoneal dialysis (PD).

DESIGN

Retrospective analysis of a group of patients whose peritoneal function was prospectively followed.

SETTING

A tertiary-care public university hospital.

PATIENTS

Nineteen of 90 long-term PD patients required a peritoneal resting period to recover UF capacity: 8 had this requirement before the third year on PD (early, EUFF group) and 11 had a late requirement (LUFF group). The remaining 71 patients, those with stable peritoneal function over time, constituted the control group.

MAIN OUTCOME MEASURES

Peritoneal UF capacity under standard conditions (monthly) and small solute peritoneal transport (yearly).

RESULTS

None of the conditions appearing at the start of PD or during the observation period could be definitely identified as the cause of UFF. There were no differences in characteristics between the EUFF group and the other two groups, except for the higher prevalence of diabetes in the EUFF group. Residual renal function (RRF) declined in all three groups during the first 2 years, with rapid loss during the third year in the EUFF group. This rapid loss in RRF was coincident with UFF. Peritoneal solute and water transport at baseline was similar in the three groups. After 2 years on PD, individuals in the EUFF group showed a significantly lower UF and higher creatinine mass transfer coefficient values than those in the LUFF group. Diabetic patients in the control group showed remarkable stability in UF capacity over time. During the second year on PD, requirement for increases in dialysate glucose concentration was 3.4 +/- 0.5% in the LUFF group, but as high as 25.5 +/- 24.2% in the EUFF group. The accumulated days of active peritonitis (APID, days with cloudy effluent) were similar for the three groups after 1, 2, and 3 years on PD. Interestingly, diabetic patients in the control group showed an APID index significantly lower than the overall EUFF group. Diabetics in the control group also had significantly lower APID versus nondiabetics in the control group (p = 0.016).

CONCLUSIONS

Our findings suggest that certain patients develop early UFF type I. Diabetic state and a higher glucose requirement to obtain adequate UF suggest that glucose on both sides of the peritoneal membrane could be responsible. The mechanisms for this higher requirement remain to be elucidated. The identification of a larger cohort of these early UFF patients should lead to a better exploration of the primary pathogenic mechanisms.

Short-term recombinant human growth hormone therapy does not modify growth hormone, thyrotropin and prolactin responses to thyrotropin-releasing hormone in adult dialysis patients

BACKGROUND

We recently have reported the first randomized, controlled study on the effects of short-term recombinant human growth hormone (rhGH|| therapy on the nutritional status of a group of malnourished adult dialysis patients. In order to evaluate whether rhGH administration exerts any influence on GH, thyrotropin (TSH|| and prolactin (PRL|| responses to TSH-releasing hormone (TRH||, we assessed these responses before and after rhGH therapy.

METHODS

GH, PRL and TSH responses to TRH before and 1 month after rhGH therapy in a group of adult dialysis patients were evaluated. Seventeen dialysis patients (11 on continuous ambulatory peritoneal dialysis/six on haemodialysis|| were studied (rhGH group, n=8; control group, n=9||. In the rhGH group, 0.2 IU/kg/day rhGH was administered subcutaneously. Each patient was tested with TRH (400 microg bolus i.v.|| on two separate occasions, just before and immediately after the treatment period.

RESULTS

rhGH treatment did not modify baseline serum GH concentrations (6.6+/-2.7 vs 4.1+/-1.1 microg/l||, paradoxical GH responses to TRH (six out of eight patients||, GH peak (11.9+/-4.6 vs 11.2+/-5.3 microg/l, NS|| or area under the secretory curve of GH (GH AUC; 19.1+/-4.5 vs 12.1+/-3.1 microg/h/l||. Both basal PRL (35.5+/-7.1 vs 36.7+/-8.6 microg/l|| and TSH (2.3+/-1.1 vs 2.8+/-1.7 mU/l|| concentrations, as well as their responses to TRH stimulation (PRL peak, 59.9+/-16.6 vs 59. 5+/-11.8 microg/l; TSH peak, 6.2+/-2.6 vs 7.1+/-3.9 mU/l||, were also unaffected by rhGH therapy.

CONCLUSION

These results suggest that short-term rhGH therapy does not significantly influence the magnitude of the somatotropic, lactotropic or thyrotropic response to TRH in adult dialysis patients. However, this finding has to be interpreted with caution due to the two different patient groups included in this study.

Protein-losing enteropathy is associated with peritoneal functional abnormalities in peritoneal dialysis patients

OBJECTIVE

To evaluate the relationship between acquired peritoneal transport disorders and the presence of protein-losing enteropathy (PLE), and their contribution to the protein malnutrition in peritoneal dialysis (PD) patients.

PATIENTS AND METHODS

We studied 31 clinically stable PD patients that received a fat overload diet for 3 days. We measured intestinal absorption of fecal fat (normal < 6 g/24-hour stool) and nitrogen (normal < 2 g/24-hr stool), intestinal protein permeability [fecal clearance of alpha1-antitrypsin (Calpha1AT) (normal < 12 mL/24-hr stool)], and nutritional markers [normalized protein nitrogen appearance (nPNA), half-life medium-term proteins, and body mass index]. Peritoneal solute transport was measured by mass transfer coefficient (MTC), and water transport by peritoneal ultrafiltration (UF) capacity. To define protein maldigestion it was necessary to find high fecal nitrogen values with normal Calpha1AT; PLE was defined when both values were elevated.

RESULTS

High fecal nitrogen (mean 2.1+/-1 g/24-hr stool) and fat (mean 5.8+/-3.6 g/24-hr stool) were found in 15 patients; 6 patients had high Calpha1AT levels (PLE). These 6 patients showed a worse nutritional status: lower albumin (3.57+/-0.57 g/dL vs 3.98+/-0.38 g/dL, p < 0.05) and transferrin (243+/-70 mg/dL vs 272+/-44.3 mg/dL, p < 0.05), as well as lower triglycerides (131.3+/-31.7 mg/dL vs 187+/-116 mg/dL, p< 0.05). Higher urea MTCs were found in 10 patients, normal in 7, and lower in 14. Higher creatinine MTCs were found in 8 patients, normal in 15, and lower in 8. Normal peritoneal UF capacity was found in 25 and lower in 6 patients. These 6 patients showed higher urea and creatinine MTCs and Calpha1AT. A positive linear correlation between Calpha1AT, urea MTC (r = 0.56, p < 0.01), and creatinine MTC (r = 0.46, p < 0.01) was found. A similar situation occurred between Calpha1AT, fecal fat (r = 0.45, p < 0.05), and fecal nitrogen (r = 0.43, p < 0.05). Thirteen patients with previous history of peritonitis showed higher Calpha1AT than those without peritonitis (10.2+/-8 mL/24-hr stool vs 5.2+/-4.4 mL/24-hr stool, p < 0.05).

CONCLUSIONS

We confirm that protein and fat malabsorption, maldigestion, and PLE are present in some PD patients. Higher fecal Calpha1AT is associated with malnutrition and poorer showings of the viability markers of peritoneal membrane function.

[Methods to assess the ex vivo growth capacity of mesothelial cells obtained directly from peritoneal effluent]

The anatomical and functional integrity of mesothelial cells (MC) is necessary for peritoneal membrane stability. At present, there is no satisfactory method to assess MC function and regenerative capacity in individual peritoneal dialysis (PD) patients. MC may be cultured from peritoneal biopsy specimens, but peritoneal biopsy is an invasive procedure that cannot be performed serially. The aim of this study is to explore the feasibility of serial culture of MC from the peritoneal effluent of PD patients. Fifty-two randomly selected PD patients were studied. MC were obtained from the peritoneal effluent of nocturnal 2.27% glucose exchanges and cultured in T25 tissue culture flasks. Subconfluent MC cultures were obtained in 80.7% of patients. At this stage, the percentage of cells in the tissue cultured flask characterized as MC by morphology and immunostaining had increased to 95.5%. MC were then subcultured in multi-well culture plates, where they showed exponential cell growth until day 16. Nine (17%) patients released low numbers of MC into the effluent and MC could not be cultured to subconfluence. One additional patient released and apparently adequate number of MC that repeatedly failed to reach confluence. Patients showed the same behavior in several cultures performed. In conclusion, peritoneal MC released into peritoneal effluent are accessible for profound analysis by a culture technique. This technique opens the possibility of serial follow-up of the biology of MC individual PD patients.