Associations between urinary cysteine-rich protein 61 excretion and kidney function decline in outpatients with chronic kidney disease: a prospective cohort study in Taiwan.

OBJECTIVES: To examine whether urinary excretion of cysteine-rich protein 61 (Cyr61), an acknowledged proinflammatory factor in kidney pathologies, increases in chronic kidney disease (CKD) and is associated with subsequent rapid kidney function decline. DESIGN: An observational cohort study. SETTING: In the nephrology outpatient clinics of a tertiary hospital in Taiwan. PARTICIPANTS: We enrolled 138 adult CKD outpatients (n=12, 32, 18, 18, 29 and 29 in stages 1, 2, 3a, 3b, 4 and 5 CKD, respectively) between February and October 2014 and followed them for 1 year. Their mean age was 60.46±13.16 years, and 51 (37%) of them were women. PRIMARY OUTCOME MEASURES: Urinary Cyr61 levels were measured by ELISA. Rapid kidney function decline was defined as an estimated glomerular filtration rate (eGFR) decline rate ≥ 4 mL/min/1.73 m2/year or developing end-stage renal disease during subsequent 3-month or 1-year follow-up period. Models were adjusted for demographic and clinical variables. RESULTS: The urine Cyr61-to-creatinine ratio (UCyr61CR) increased significantly in patients with stage 4 or 5 CKD. Multivariable linear regression analysis showed that log(UCyr61CR) was positively correlated with log(urine protein-to-creatinine ratio) (p<0.001) but negatively correlated with baseline eGFR (p<0.001) and hypertension (p=0.007). Complete serum creatinine data during the follow-up were available for 112 patients (81.2%). Among them, multivariable logistic regression identified log(UCyr61CR) was independently associated with rapid kidney function decline (adjusted OR 2.29, 95% CI 1.27 to 4.15) during the subsequent 3 months. UCyr61CR improved the discriminative performance of clinical models to predict 3-month rapid kidney function decline. In contrast, log(UCyr61CR) was not associated with rapid eGFR decline during the entire 1-year follow-up. CONCLUSIONS: Elevated urinary Cyr61 excretion is associated with rapid short-term kidney function deterioration in patients with CKD. Measuring urinary Cyr61 excretion is clinically valuable for monitoring disease trajectory and may guide treatment planning.

Therapeutic efficacy of pentoxifylline on proteinuria and renal progression: an update.

Blood pressure control with renin-angiotensin system (RAS) blockade has remained the gold standard for treating patients with proteinuric chronic kidney disease (CKD) up to date. Nevertheless, RAS blockade slows but does not halt the progression of kidney disease, thus highlighting the need to search for additional therapeutic approaches. The nonselective phosphodiesterase (PDE) inhibitor pentoxifylline (PTX) is an old drug that exhibits prominent anti-inflammatory, anti-proliferative and anti-fibrotic activities both in vitro and in vivo. Studies in human subjects have shown that PTX monotherapy decreases urinary protein excretion, and add-on therapy of PTX to background RAS blockade additively reduces proteinuria in patients with CKD of various etiology. More recent studies find that PTX combined with RAS blockade delays the decline of glomerular filtration rate in diabetic patients with mild to moderate CKD, and reduces the risk of end-stage renal disease in diabetic and non-diabetic patients in late stage of CKD with high proteinuria levels. In this review, we update the clinical trial results of PTX as monotherapy, or in conjunction or in comparison with RAS blockade on patients with proteinuria and CKD, and propose a mechanistic scheme explaining the renoprotective activities of this drug.

Membranous nephropathy: a review on the pathogenesis, diagnosis, and treatment.

In adults, membranous nephropathy (MN) is a major cause of nephrotic syndrome. However, the etiology of approximately 75% of MN cases is idiopathic. Secondary causes of MN are autoimmune diseases, infection, drugs, and malignancy. The pathogenesis of MN involves formation of immune complex in subepithelial sites, but the definite mechanism is still unknown. There are three hypotheses about the formation of immune complex, including preformed immune complex, in situ immune-complex formation, and autoantibody against podocyte membrane antigen. The formation of immune complex initiates complement activation, which subsequently leads to glomerular damage. Recently, the antiphospholipase A2 receptor antibody was found to be associated with idiopathic MN. This finding may be useful in the diagnosis and prognosis of MN. The current treatment includes best supportive care, which consists of the use of angiotensin-converting enzyme inhibitors/angiotensin II receptor blockers, lipid-lowering agents, and optimal control of blood pressure. Immunosuppressive agents should be used for patients who suffer from refractory proteinuria or complications associated with nephrotic syndrome. Existing evidence supports the use of a combination of steroid and alkylating agents. This article reviews the epidemiology, pathogenesis, diagnosis, and the treatment of MN.

Multidisciplinary care program for advanced chronic kidney disease: reduces renal replacement and medical costs.

BACKGROUND: Multidisciplinary care is advocated as an effective chronic kidney disease treatment program in a few, but not all, studies. Our study aimed to evaluate the effect of multidisciplinary care on renal outcome and patient survival using a larger cohort. METHOD: A total 1382 chronic kidney disease patients, ages 18-80 years, with chronic kidney disease stage 3B-5, in nephrology outpatient clinics were enrolled. Using age, sex, chronic kidney disease stage, and diabetes mellitus as variables, 592 multidisciplinary care program participants were matched with 614 nonmultidisciplinary care patients. The primary outcomes were long-term renal replacement therapy and mortality. Secondary outcomes included changes of biochemical markers and blood pressure, infection hospitalization, cardiovascular events, and emergent start of long-term dialysis. Annual medical costs were compared. RESULTS: There were no between-group differences regarding mortality. In the multivariate competing-risk regression model, the multidisciplinary care group had a better renal survival (hazard ratio 0.640; 95% confidence interval, 0.484-0.847; P = .002). This effect was most prominent in stage 4 (hazard ratio 0.375; 95% confidence interval, 0.219-0.640; P < .001), but not in stage 3B and 5 patients. The multidisciplinary care group showed a slower estimated glomerular filtration rate decline (-2.57 vs -3.74 mL/min/1.73 m(2), P = .021), and a smaller increase in phosphate (+ 0.03 vs + 0.33 mg/dL, P = .013). Cardiovascular and infection events were both decreased in the multidisciplinary care group (P < .001). There was also less requirement of emergent start dialysis (39.6% vs 54.5%, P = .001). The annual cost for the multidisciplinary care group was lower than the nonmultidisciplinary care group (US $2372 vs $3794, P < .001). In addition, considering the reduction of patients requiring renal replacement therapy, the multidisciplinary care program saved a total US $1931 per patient annually. CONCLUSIONS: Our analysis demonstrated that the multidisciplinary care program provided better health care and reduced renal replacement therapy in patients with advanced chronic kidney disease. By decreasing hospitalizations, emergent start, and the need for renal replacement therapy, the multidisciplinary care program was cost-effective.

Blockade of cysteine-rich protein 61 attenuates renal inflammation and fibrosis after ischemic kidney injury.

Emerging data have suggested that acute kidney injury (AKI) is often incompletely repaired and can lead to chronic kidney disease (CKD), which is characterized by tubulointerstitial inflammation and fibrosis. However, the underlying mechanisms linking AKI to CKD remain obscure. The present study aimed to investigate the role of cysteine-rich protein 61 (Cyr61) after unilateral kidney ischemia-reperfusion injury (IRI) in mice. After IRI, increased expression of Cyr61 was detected, predominately in the proximal tubular epithelium. This was confirmed by in vitro experiments, which showed that hypoxia stimulated Cyr61 expression in cultured proximal tubular epithelial cells. The proinflammatory property of Cyr61 was indicated by its ability to upregulate monocyte chemoattractant protein-1 and IL-6. Additionally, we found elevated urinary Cyr61 excretion in patients with AKI. Notably, treatment of mice with an anti-Cyr61 antibody attenuated the upregulation of kidney monocyte chemoattractant protein-1, IL-6, IL-1ß, and macrophage inflammatory protein-2 and reduced the infiltration of F4/80-positive macrophages on days 7 and 14 after IRI. In addition, blockade of Cyr61 reduced the mRNA expression of collagen, transforming growth factor-ß, and plasminogen activator inhibitor-I as well as the degree of collagen fibril accumulation, as evaluated by picrosirius red staining, and levels of α-smooth muscle actin proteins by day 14. Concurrently, in the treated group, peritubular microvascular density was more preserved on day 14. We conclude that Cyr61 blockade inhibits the triad of inflammation, interstitial fibrosis, and capillary rarefaction after severe ischemic AKI. The results of this study expand the knowledge of the mechanisms underlying the AKI-to-CKD transition and suggest that Cyr61 is a potential therapeutic target.

Lineage tracing reveals distinctive fates for mesothelial cells and submesothelial fibroblasts during peritoneal injury.

Fibrosis of the peritoneal cavity remains a serious, life-threatening problem in the treatment of kidney failure with peritoneal dialysis. The mechanism of fibrosis remains unclear partly because the fibrogenic cells have not been identified with certainty. Recent studies have proposed mesothelial cells to be an important source of myofibroblasts through the epithelial-mesenchymal transition; however, confirmatory studies in vivo are lacking. Here, we show by inducible genetic fate mapping that type I collagen-producing submesothelial fibroblasts are specific progenitors of α-smooth muscle actin-positive myofibroblasts that accumulate progressively in models of peritoneal fibrosis induced by sodium hypochlorite, hyperglycemic dialysis solutions, or TGF-ß1. Similar genetic mapping of Wilms' tumor-1-positive mesothelial cells indicated that peritoneal membrane disruption is repaired and replaced by surviving mesothelial cells in peritoneal injury, and not by submesothelial fibroblasts. Although primary cultures of mesothelial cells or submesothelial fibroblasts each expressed α-smooth muscle actin under the influence of TGF-ß1, only submesothelial fibroblasts expressed α-smooth muscle actin after induction of peritoneal fibrosis in mice. Furthermore, pharmacologic inhibition of the PDGF receptor, which is expressed by submesothelial fibroblasts but not mesothelial cells, attenuated the peritoneal fibrosis but not the remesothelialization induced by hypochlorite. Thus, our data identify distinctive fates for injured mesothelial cells and submesothelial fibroblasts during peritoneal injury and fibrosis.

Renoprotective effect of combining pentoxifylline with angiotensin-converting enzyme inhibitor or angiotensin II receptor blocker in advanced chronic kidney disease.

BACKGROUND/PURPOSE: Several studies have shown the renoprotective effects of pentoxifylline in the treatment of chronic kidney disease (CKD). This study was conducted to examine whether there was an increased benefit of including pentoxifylline with angiotensin-converting enzyme inhibitor (ACEI) or angiotensin II receptor blocker (ARB) in the treatment of CKD. METHODS: A single-center retrospective analysis was conducted. A total of 661 Stage 3B-5 CKD patients who received ACEI or ARB treatment were recruited. The patients were divided into the pentoxifylline use group and the no pentoxifylline group. Renal survival analysis of the two groups was compared. Subgroup analysis was performed by dividing the patients into lower [urine protein to creatinine ratio (UPCR)<1 g/g] and higher (UPCR ≥ 1 g/g) proteinuria subgroups. RESULTS: There was no between-groups difference regarding mortality and cardiovascular events. Addition of pentoxifylline showed a better renal outcome (p = 0.03). The protective effect of add-on pentoxifylline was demonstrated in the higher proteinuria subgroup (p = 0.005). In the multivariate Cox regression model, pentoxifylline use also showed a better renal outcome [hazard ratio (HR): 0.705; 95% confidence interval (CI): 0.498-0.997; p = 0.048]. This effect was more prominent in the higher proteinuria subgroup (HR: 0.602; 95% CI: 0.413-0.877; p = 0.008). CONCLUSION: In the advanced stages of CKD, patients treated with a combination of pentoxifylline and ACEI or ARB had a better renal outcome than those treated with ACEI or ARB alone. This effect was more prominent in the higher proteinuria subgroup. More large randomized control trials are needed to provide concrete evidence of the add-on effect of pentoxifylline.

Angiopoietins modulate endothelial adaptation, glomerular and podocyte hypertrophy after uninephrectomy.

Glomerular capillary remodeling is an essential process in the development of glomerular hypertrophy. Angiopoietins, which are important regulators in angiogenesis, plays a role in the development of glomerulus during embryogenesis. Here, we evaluated the influence of angiopoietin on glomerular components and hypertrophy after uninephrectomy in adult male BALB/c mice. The actions of angiopoietin 1 or 2 were systemically antagonized by the subcutaneous administration of antagonists. We observed that the angiopoietin system was activated after uninephrectomy, and that the blockade of angiopoietin 1 or 2 decreased the activation of the angiopoietin receptor--tyrosine kinase with Ig and EGF homology domains-2--and attenuated the development of glomerular and podocyte hypertrophy. The increase in endothelial density staining (anti-CD31) following uninephrectomy was also reversed by angiopoietin 1 or 2 blockades. Glomerular basement thickness and foot process width were observed to decrease in the angiopoietin blockade groups. These changes were associated with the down regulation of the expression of genes for the glomerular matrix and basement membrane, including collagen type IV α1, collagen type IV α2, collagen type IV α5, and laminin α5. Thus, angiopoietin 1 or 2 may play an important role in the development of glomerular hypertrophy after uninephrectomy. A blockade of the angiopoietin system not only influenced the endothelium but also the podocyte, leading to diminished gene expression and morphological changes after uninephrectomy.

Lifetime costs for peritoneal dialysis and hemodialysis in patients in Taiwan.

BACKGROUND: This study compared the lifetime costs for peritoneal dialysis (PD) and hemodialysis (HD) patients in Taiwan. METHODS: Using the National Health Insurance (NHI) database of all end-stage renal disease patients on maintenance dialysis registered from July 1997 to December 2005, we matched eligible PD patients with eligible HD patients on age, sex, and diabetes status. The matched patients were followed until 31 December 2006. Patients were excluded if they were less than 18 years of age, had been diagnosed with cancer before dialysis, or had been dialyzed at centers or clinics other than hospitals. Outcomes-including life expectancy, total lifetime costs, and costs per life-year paid by the NHI-were estimated and compared. RESULTS: The 3136 pairs of matched PD and HD patients had a mean age of 53.2 ± 15.4 years. The total lifetime cost for PD patients (US$139 360 ± US$8 336) was significantly lower than that for HD patients (US$185 235 ± US$9 623, p < 0.001). Except for patients with diabetes (who had a short life expectancy), the total lifetime cost was significantly lower for PD patients than for HD patients regardless of sex and age (p < 0.01). CONCLUSION: In Taiwan, the total lifetime costs paid by the NHI were lower for PD than for HD patients.

Cysteine-rich protein 61 plays a proinflammatory role in obstructive kidney fibrosis.

Cysteine-rich protein 61 (Cyr61) is a secreted matrix-associated protein that regulates a broad spectrum of biological and cellular activities. This study aimed to investigate the role of Cyr61 in progressive kidney fibrosis induced by unilateral ureteral obstruction (UUO) surgery in mice. The expression of Cyr61 transcripts and proteins in the obstructed kidneys were increased from day 1 and remained high until day 10 after surgery. Immunohistochemistry indicated that Cyr61 was expressed mainly in renal tubular epithelial cells. The upregulated Cyr61 in UUO kidneys was reduced in mice treated with pan-transforming growth factor-ß (TGF-ß) antibody. The role of TGF-ß in tubular Cyr61 upregulation after obstructive kidney injury was further supported by experiments showing that TGF-ß1 stimulated Cyr61 expression in cultured tubular epithelial cells. Notably, the upregulation of Cyr61 in UUO kidneys was followed by a marked increase in monocyte chemoattractant protein 1 (MCP-1) transcripts and macrophage infiltration, which were attenuated in mice treated with anti-Cyr61 antibodies. This proinflammatory property of Cyr61 in inducing MCP-1 expression was further confirmed in tubular epithelial cells cultured with Cyr61 protein. The anti-Cyr61 antibody in UUO mice also reduced the levels of collagen type 1-α1 transcripts, collagen fibril accumulation evaluated by picrosirius red staining, and the levels of α-smooth muscle actin (α-SMA) transcripts and proteins on day 4 after surgery; however, the antifibrotic effect was not sustained. In conclusion, the TGF-ß-mediated increase in tubular Cyr61 expression involved renal inflammatory cell infiltration through MCP-1 induction during obstructive kidney injury. The Cyr61 blockade attenuated kidney fibrosis in the early phase, but the antifibrotic effect could not be sustained.

Women on hemodialysis have lower self-reported health-related quality of life scores but better survival than men.

BACKGROUND: Hemodialysis patients suffer from poor quality of life and survival. A retrospective cohort study was performed to examine the sex differences in self-reported quality of life and mortality in a Taiwanese hemodialysis cohort. METHODS: A total of 816 stable hemodialysis patients were included. Patients completed two questionnaires: the 36-item Short Form Health Survey Questionnaire (SF-36, Taiwan Standard Version 1.0) to assess health-related quality of life (HRQoL) and the Beck Depression Inventory (BDI, Chinese Version) to assess depressive mood. Mortality outcomes were recorded for a seven-year follow-up period. RESULTS: After adjustment for confounding factors, women had significantly higher BDI scores (P=.003), lower physical functioning (P<.001), bodily pain (P<.001), mental health (P=0007), and physical component scale (PCS) scores (P<.001). There were 284 deaths recorded. In the Cox-proportional hazard model, women had significantly lower mortality than men (P<.001). CONCLUSIONS: Women on hemodialysis had more depression-related symptoms and poor self-reported HRQoL, but better survival than men. The sex difference in psychological and HRQoL issues deserves greater concern because this relates to clinical care and further study.

Transforming growth factor ß-1 stimulates profibrotic epithelial signaling to activate pericyte-myofibroblast transition in obstructive kidney fibrosis.

Pericytes have been identified as the major source of precursors of scar-producing myofibroblasts during kidney fibrosis. The underlying mechanisms triggering pericyte-myofibroblast transition are poorly understood. Transforming growth factor ß-1 (TGF-ß1) is well recognized as a pluripotent cytokine that drives organ fibrosis. We investigated the role of TGF-ß1 in inducing profibrotic signaling from epithelial cells to activate pericyte-myofibroblast transition. Increased expression of TGF-ß1 was detected predominantly in injured epithelium after unilateral ureteral obstruction, whereas downstream signaling from the TGF-ß1 receptor increased in both injured epithelium and pericytes. In mice with ureteral obstruction that were treated with the pan anti-TGF-ß antibody (1D11) or TGF-ß receptor type I inhibitor (SB431542), kidney pericyte-myofibroblast transition was blunted. The consequence was marked attenuation of fibrosis. In addition, epithelial cell cycle G2/M arrest and production of profibrotic cytokines were both attenuated. Although TGF-ß1 alone did not trigger pericyte proliferation in vitro, it robustly induced α smooth muscle actin (α-SMA). In cultured kidney epithelial cells, TGF-ß1 stimulated G2/M arrest and production of profibrotic cytokines that had the capacity to stimulate proliferation and transition of pericytes to myofibroblasts. In conclusion, this study identified a novel link between injured epithelium and pericyte-myofibroblast transition through TGF-ß1 during kidney fibrosis.

Fibrin-Induced epithelial-to-mesenchymal transition of peritoneal mesothelial cells as a mechanism of peritoneal fibrosis: effects of pentoxifylline.

Excessive fibrin deposition in the peritoneum is thought to be involved in the development of encapsulating peritoneal sclerosis (EPS), an important cause of morbidity and mortality in peritoneal dialysis patients. We investigated fibrin-induced epithelial-to-mesenchymal transition (EMT) of peritoneal mesothelial cells (PMCs) as a possible mechanism of fibrin involvement in EPS. In vitro, fibrin overlay of PMCs altered their morphology; increased α-smooth muscle actin, fibronectin, fibroblast specific protein-1, and α(v)ß(3) integrin expression; and decreased cytokeratin 18 and E-cadherin expression. Fibrin overlay also increased focal adhesion kinase and Src kinase phosphorylation. Fibrin-induced changes were inhibited by treating the cells with α(v)ß(3) integrin antibody or pentoxifylline (PTX). In a rat model, intraperitoneal injection of Staphylococcus aureus and fibrinogen induced severe EPS features, which were attenuated by PTX treatment. PTX-treated rats also showed preserved peritoneal ultrafiltration function and lower concentrations of cytokines than the untreated rats. S. aureus- and fibrinogen-injected rats had higher percentage of cytokeratin-positive cells in the omentum fibrotic tissue than controls; this was also reduced by PTX treatment. Our results suggest that fibrin induces EMT of PMCs by engaging α(v)ß(3) integrin and activating associated kinases. Our EPS animal model showed that fibrin-induced EMT was involved in the pathogenesis of peritoneal fibrosis and was inhibited by PTX.

Clinical outcomes and predictors for ESRD and mortality in primary GN.

BACKGROUND AND OBJECTIVES: Relatively little is known about the long-term outcomes of different histologic types of primary glomerulonephritis in Asian populations. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: From 1993 to 2006, 987 patients undergoing renal biopsy were studied, and 580 patients (mean age=44.4 years, male=58.5%) with the four most common forms of glomerulonephritis (membranous nephropathy, focal and segmental glomerulosclerosis, IgA nephropathy, and minimal change disease) were selected for analysis. Median follow-up period was 5.9 (interquartile range=5.7) years. RESULTS: The focal and segmental glomerulosclerosis group displayed the highest incidence of ESRD (25.8%) and the fastest decline of estimated GFR (4.6 ml/min per 1.73 m(2) per year). The IgA nephropathy group also had a higher rate of ESRD than the membranous nephropathy patients (19.2% versus 4.3%, P<0.001). In contrast, the membranous nephropathy group exhibited an overall death rate similar to the focal and segmental glomerulosclerosis group (17.2% versus 14.4%) but higher than the IgA nephropathy and minimal change disease patients (4.6% and 3.7%, respectively, P<0.001). The most powerful predictor for ESRD was focal and segmental glomerulosclerosis, whereas the strongest predictor for all-cause mortality was membranous nephropathy with higher proteinuria. Protectors against ESRD included male sex and higher hemoglobin. CONCLUSIONS: Most predictors for ESRD and overall mortality found in this ethnic Chinese cohort were similar to other studies. However, some risk factors linked with distinct glomerular pathologies displayed differential clinical outcomes.

Effect of diuretic use on 30-day postdialysis mortality in critically ill patients receiving acute dialysis.

BACKGROUND: The impact of diuretic usage and dosage on the mortality of critically ill patients with acute kidney injury is still unclear. METHODS AND RESULTS: In this prospective, multicenter, observational study, 572 patients with postsurgical acute kidney injury receiving hemodialysis were recruited and followed daily. Thirty-day postdialysis mortality was analyzed using Cox's proportional hazards model with time-dependent covariates. The mean age of the 572 patients was 60.8±16.6 years. Patients with lower serum creatinine (p = 0.031) and blood lactate (p = 0.033) at ICU admission, lower predialysis urine output (p = 0.001) and PaO(2)/FiO(2) (p = 0.039), as well as diabetes (p = 0.037) and heart failure (p = 0.049) were more likely to receive diuretics. A total of 280 (49.0%) patients died within 30 days after acute dialysis initiation. The analysis of 30-day postdialysis mortality by fitting propensity score-adjusted Cox's proportional hazards models with time-dependent covariates showed that higher 3-day accumulated diuretic doses after dialysis initiation (HR = 1.449, p = 0.021) could increase the hazard rate of death. Moreover, higher time-varying 3-day accumulative diuretic doses were associated with hypotension (p<0.001) and less intense hemodialysis (p<0.001) during the acute dialysis period. BACKGROUND AND SIGNIFICANCE: Higher time-varying 3-day accumulative diuretic dose predicts mortality in postsurgical critically ill patients requiring acute dialysis. Higher diuretic doses are associated with hypotension and a lower intensity of dialysis. Caution should be employed before loop diuretics are administered to postsurgical patients during the acute dialysis period.

Safety issues of long-term glucose load in patients on peritoneal dialysis--a 7-year cohort study.

BACKGROUND: Effects of long-term glucose load on peritoneal dialysis (PD) patient safety and outcomes have seldom been reported. This study demonstrates the influence of long-term glucose load on patient and technique survival. METHODS: We surveyed 173 incident PD patients. Long-term glucose load was evaluated by calculating the average dialysate glucose concentration since initiation of PD. Risk factors were assessed by fitting Cox's models with repeatedly measured time-dependent covariates. RESULTS: We noted that older age, higher glucose concentration, and lower residual renal function (RRF) were significantly associated with a worse patient survival. We found that female gender, absence of diabetes, lower glucose concentration, use of icodextrin, higher serum high density lipoprotein cholesterol, and higher RRF were significantly associated with a better technique survival. CONCLUSIONS: Long-term glucose load predicted mortality and technique failure in chronic PD patients. These findings emphasize the importance of minimizing glucose load in PD patients.