Effect of Low Protein Diet Supplemented with Ketoanalogs on Endothelial Function and Protein-Bound Uremic Toxins in Patients with Chronic Kidney Disease

Studies have demonstrated that a low-protein diet supplemented with ketoanalogs (KAs) could significantly retard progression of renal function in patients with chronic kidney disease (CKD) stages 3-5. However, its effects on endothelial function and serum levels of protein-bound uremic toxins remain elusive. Therefore, this study explored whether a low-protein diet (LPD) supplemented with KAs affects kidney function, endothelial function, and serum uremic toxin levels in a CKD-based cohort. In this retrospective cohort, we enrolled 22 stable CKD stage 3b-4 patients on LPD (0.6-0.8 g/day). Patients were categorized into control (LPD only) and study groups (LPD + KAs 6 tab/day). Serum biochemistry, total/free indoxyl sulfate (TIS/FIS), total/free p-cresyl sulfate (TPCS/FPCS), and flow-mediated dilation (FMD) were measured before and after 6 months of KA supplementation. Before the trial, there were no significant differences in kidney function, FMD, or uremic toxin levels between the control and study groups. When compared with the control group, the paired t-test showed a significant decrease in TIS and FIS (all p < 0.05) and a significant increase in FMD, eGFR, and bicarbonate (all p < 0.05). In multivariate regression analysis, an increase in FMD (p < 0.001) and a decrease in FPCS (p = 0.012) and TIS (p < 0.001) remained persistent findings when adjusted for age, systolic blood pressure (SBP), sodium, albumin, and diastolic blood pressure (DBP). LPD supplemented with KAs significantly preserves kidney function and provides additional benefits on endothelial function and protein-bound uremic toxins in patients with CKD.

Prediction of Intradialytic Blood Pressure Variation Based on Big Data

INTRODUCTION

Cardiovascular (CV) events are the major cause of morbidity and mortality associated with blood pressure (BP) in hemodialysis (HD) patients. BP varies significantly during HD treatment, and the dramatic variation in BP is a well-recognized risk factor for increased mortality. The development of an intelligent system capable of predicting BP profiles for real-time monitoring is important. Our aim was to build a web-based system to predict changes in systolic BP (SBP) during HD.

METHODS

In this study, dialysis equipment connected to the Vital Info Portal gateway collected HD parameters that were linked to demographic data stored in the hospital information system. There were 3 types of patients: training, test, and new. A multiple linear regression model was built using the training group with SBP change as the dependent variable and dialysis parameters as the independent variables. We tested the model's performance on test and new patient groups using coverage rates with different thresholds. The model's performance was visualized using a web-based interactive system.

RESULTS

A total of 542,424 BP records were used for model building. The accuracy was greater than 80% in the prediction error range of 15%, and 20 mm Hg of true SBP in the test and new patient groups for the model of SBP changes suggested the good performance of our prediction model. In the analysis of absolute SBP values (5, 10, 15, 20, and 25 mm Hg), the accuracy of the SBP prediction increased as the threshold value increased.

DISCUSSION

This databae supported our prediction model in reducing the frequency of intradialytic SBP variability, which may help in clinical decision-making when a new patient receives HD treatment. Further investigations are needed to determine whether the introduction of the intelligent SBP prediction system decreases the incidence of CV events in HD patients.

Risk associated with estimated glomerular filtration rate and albuminuria for PAD among patients with type 2 diabetes

Chronic kidney disease (CKD) is significantly associated with peripheral arterial disease (PAD) in some studies, but data on the association of the risk of PAD across a broad range of kidney function in patients with type 2 diabetes are limited. Between October 17, 2013 and February 7, 2015, all consecutive outpatients with type 2 diabetes underwent ankle-brachial index (ABI) examination. We investigated the association of estimated glomerular filtration rate (eGFR) and albumin-to-creatinine ratio (ACR) with the risk of PAD. A total of 1254 patients were cross-classified into 12 groups based on ACR category (normoalbuminuria, microalbuminuria and macroalbuminuria) and eGFR stage (≥90, 60-89, 30-59 and <30 mL/min/1.73 m²). Logistic regression analysis was used to investigate the association of eGFR and ACR with PAD. Within each ACR category, a lower eGFR stage was associated with PAD. Similarly, within each eGFR group, a higher ACR category was also associated with PAD. The OR for PAD was highest in patients with eGFR <30 mL/min/1.73 m² and macroalbuminuria (OR 14.42, 95% CI 4.60 to 45.31) when compared with the reference group of subjects with eGFR ≥90 mL/min/1.73 m² and normoalbuminuria. Our study found that cross-classification of eGFR with ACR revealed a more comprehensive association with risk of PAD than eGFR or ACR alone.

Effects of replacing soybean meal with pumpkin seed cake and dried distillers grains with solubles on milk performance and antioxidant functions in dairy cows

Pumpkin seed cake (PSC), a byproduct of pumpkin seed oil processing, is used in ruminant feed as a beneficial protein source. Experiments were conducted to evaluate PSC as a substitute for soybean meal in the diets of lactating cows based on performance, rumen fermentation, antioxidant function and nitrogen partitioning. Six multiparous lactating cows were used in a replicated 3 × 3 Latin square experiment with 27-day periods. The cows were randomly divided into three treatment groups: group (1) was fed a diet containing no PSC (0PSC), and groups (2) and (3) were fed diets in which soybean meal was replaced with PSC and dried distillers grains with solubles (DDGS) at levels of 50% (50PSC) and 100% (100PSC), respectively. The diets were isonitrogenous and contained identical roughage but different proportions of PSC and DDGS. Replacement of soybean meal with PSC and DDGS did not influence rumen degradation, milk performance, rumen fermentation, DM intake or apparent total tract digestibility, and nitrogen partitioning between milk, feces and urine did not differ in the animals fed the three diets. However, compared with a diet containing no PSC, the total antioxidant capacity (P < 0.05) and antioxidant enzymes (total superoxide dismutase, glutathione peroxidase and catalase) activities (P < 0.05) were increased in the animals that received the 50PSC and 100PSC diets. In contrast, addition of PSC significantly reduced concentrations of aspartate transaminase (P < 0.05), alkaline phosphatase (P < 0.05) and malondialdehyde (P < 0.05) in the plasma. These results demonstrate that PSC can be completely substituted for soybean meal in the diet of dairy cows without any negative impact on milk performance, rumen fermentation or apparent digestibility and that this dietary change improves antioxidant functions and blood parameters in dairy cows, indicating that PSC has the potential for use as a feed source for dairy cows.

Dataset supporting blood pressure prediction for the management of chronic hemodialysis

Hemodialysis (HD) is a treatment given to patients with renal failure. Notable treatment-related complications include hypotension, cramps, insufficient blood flow, and arrhythmia. Most complications are associated with unstable blood pressure during HD. Physicians are devoted to seeking solutions to prevent or lower the incidence of possible complications. With advances in technology, big data have been obtained in various medical fields. The accumulated dialysis records in each HD session can be gathered to obtain big HD data with the potential to assist HD staff in increasing patient wellbeing. We generated a large stream of HD parameters collected from dialysis equipment associated with the Vital Info Portal gateway and correlated with the demographic data stored in the hospital information system from each HD session. We expect that the application of HD big data will greatly assist HD staff in treating intradialytic hypotension, setting optimal dialysate parameters, and even developing an intelligent early-warning system as well as providing individualized suggestions regarding dialysis settings in the future.

Association between trace element concentrations and anemia in patients with chronic kidney disease: a cross-sectional population-based study

Anemia is common in chronic kidney disease (CKD) and may be affected by trace element concentrations. While the concentrations of trace elements are known to be altered in CKD, the relationship between trace element and hemoglobin concentrations has not been systematically investigated in a large cohort. This study aims to examine associations between trace element concentrations and anemia in patients with CKD. Data from the National Health and Nutrition Examination Survey collected from 2011 to 2014 were used for this analysis. The participants who were more than 20 years old were included. A total of 3057 participants were included; the final cohort was divided into two groups based on CKD status. The concentrations of hemoglobin, iron, zinc, and manganese were significantly lower in participants with than without CKD (all p<0.05). Multivariate analyses showed that in patients without CKD, hemoglobin concentrations correlated positively with iron, zinc, and cadmium (β=0.005, 0.009, and 0.33, respectively), but correlated negatively with copper levels (β=-0.002). In patients with CKD, hemoglobin concentrations correlated positively with cadmium and selenium, but negatively with copper levels (β=0.57, 0.007, and -0.008, respectively). The serum iron concentration was found to correlate positively with zinc, cadmium, and selenium, but negatively with copper and manganese concentrations in the total study population (all p<0.05). The associations between serum concentrations of trace elements and hemoglobin differ between patients with and without CKD. Further investigations are warranted to determine whether patients with CKD have distinct trace element requirements.

Improvement in Mortality and End-Stage Renal Disease in Patients With Type 2 Diabetes After Acute Kidney Injury Who Are Prescribed Dipeptidyl Peptidase-4 Inhibitors

OBJECTIVE

To focus on the potential beneficial effects of the pleiotropic effects of dipeptidyl peptidase-4 inhibitors (DPP4is) on attenuating progression of diabetic kidney disease in reducing the long-term effect of the acute kidney injury (AKI) to chronic kidney disease (CKD) transition.

PATIENTS AND METHODS

Data from the National Health Insurance Research Database from January 1, 1999, to July 31, 2011, were analyzed, and patients with diabetes weaning from dialysis-requiring AKI were identified. Cox proportional hazards models and inverse-weighted estimates of the probability of treatment were used to adjust for treatment selection bias. The outcomes were incident end-stage renal disease (ESRD) and mortality, major adverse cardiovascular events, and hospitalized heart failure.

RESULTS

Of a total of 6165 patients with diabetes weaning from dialysis-requiring AKI identified, 5635 (91.4%) patients were DPP4i nonusers and 530 (8.6%) patients were DPP4i users. Compared with DPP4i nonusers, DPP4i users had a lower risk of ESRD (hazard ratio, 0.81; 95% CI, 0.70-0.94; P=.04) and all-cause mortality (hazard ratio, 0.28; 95% CI, 0.23-0.34; P<.001) after adjustments for CKD, advanced CKD, and angiotensin-converting enzyme inhibitor or angiotensin II receptor blocker use. In contrast, the risk of major adverse cardiovascular events and hospitalized heart failure did not differ significantly between groups.

CONCLUSION

Dipeptidyl peptidase-4 inhibitor users had a lower risk of ESRD and mortality than did nonusers among patients with diabetes after weaning from dialysis-requiring AKI. Therefore, a prospective study of AKI to CKD transitions after episodes of AKI is needed to optimally target DPP4i interventions.

Results of Fabry Disease Screening in Male Pre-End Stage Renal Disease Patients with Unknown Etiology Found Through the Platform of a Chronic Kidney Disease Education Program in a Northern Taiwan Medical Center

BACKGROUND/AIMS

Fabry disease (FD), a rare x-lined genetic disorder is a cause of renal deterioration. The phenotype of FD is highly variable and nonspecific, and correct diagnosis has always been delayed. We aimed to explore the prevalence and clinical presentation of FD in this high-risk male population in a Northern Taiwan medical center.

METHODS

This is the first study to survey the incidence of FD in this high-risk population through the platform of a chronic kidney disease (CKD) education program in Asia. A total of 1,012 male patients with unknown CKD causes were screened using an assay of alpha-galactosidase A activity (α-Gal A) by dried blood spots (DBS). A final GLA gene analysis was also done for those with low enzyme activity.

RESULTS

We identified two new patients with classic FD and four patients with late-onset FD. One novel GLA mutation with c.413 G>A was found in one classic FD patient (index 5). The prevalence of FD is about 0.59 % (6 in 1,012) in the high-risk population group with CKD. The clinical symptoms of FD patients are nonspecific except in those with various degrees of renal failure. Those patients' correct diagnosis was delayed, taking years and even decades. Three patients received enzyme replacement therapy and one started regular hemodialysis due to persistent renal function deterioration. Another two patients were found from family screening through a new index. In addition, a false negative result occurred in one patient who was proved to have FD by his kidney pathology as determined by this screening.

CONCLUSION

FD is not such as rare a disease and its prevalence is greater in this high-risk male population. Clinicians need to be aware that FD should be included in the differential diagnosis in CKD with unknown etiology.

Intelligent system to predict intradialytic hypotension in chronic hemodialysis

BACKGROUND

Intradialytic hypotension (IDH) is a serious complication and a major risk factor of increased mortality during hemodialysis (HD). However, predicting the occurrence of intradialytic blood pressure (BP) fluctuations clinically is difficult. This study aimed to develop an intelligent system with capability of predicting IDH.

METHODS

In developing and training the prediction models in the intelligent system, we used a database of 653 HD outpatients who underwent 55,516 HD treatment sessions, resulting in 285,705 valid BP records. We built models to predict IDH at the next BP check by applying time-dependent logistic regression analyses.

RESULTS

Our results showed the sensitivity of 86% and specificity of 81% for both nadir systolic BP (SBP) of <90 mmHg and <100 mmHg, suggesting good performance of our prediction models. We obtained similar results in validating via test data and data of newly enrolled patients (new-patient data), which is important for simulating prospective situations wherein dialysis staff are unfamiliar with new patients. This compensates for the retrospective nature of the BP records used in our study.

CONCLUSION

The use of this validated intelligent system can identify patients who are at risk of IDH in advance, which may facilitate well-timed personalized management and intervention.

Relationships between chronic comorbidities and the atherosclerosis indicators ankle-brachial index and brachial-ankle pulse wave velocity in patients with type 2 diabetes mellitus

This study aimed to determine associations between ankle-brachial index (ABI) and brachial-ankle pulse wave velocity (baPWV) with different comorbidities in patients with type 2 diabetes mellitus (DM). Records of patients with type 2 DM who received an ABI and baPWV examination between August 2013 and February 2015 were retrospectively reviewed. Associations of ABI and baPWV with chronic kidney disease (CKD), chronic liver disease (CLD), coronary artery disease (CAD) and diabetic nephropathy (DN) were examined by regression analysis. A total of 1232 patients (average age, 65.1±10.0 years) were included in the analysis. CKD and DN were associated with low ABI and increased baPWV (all, P<0.001). No associations were found between CAD and CLD and ABI or baPWV. Thus, regression analysis was performed for CKD and DN. Low ABI was associated with risk of CKD in the crude model (OR 0.724, 95% CI 0.648 to 0.808, P<0.001) and adjusted model (OR 0.872, 95% CI 0.762 to 0.999, P=0.048), whereas baPWV was only significant in the crude model (OR 1.199, 95% CI 1.112 to 1.294, P<0.001). Low ABI was associated with risk of DN in the crude model (OR 0.873, 95% CI 0.780 to 0.977, P=0.018) and adjusted model (OR 0.884, 95% CI 0.782 to 0.999, P=0.048). No association was found for baPWV. In conclusion, low ABI was associated with risk of CKD and DN in patients with type 2 diabetes.

Assessment of the pharmacokinetics, removal rate of hemodialysis, and safety of lactulose in hemodialysis patients

Lactulose is often used to treat hepatic encephalopathy or constipation, and also exhibits benefits to chronic renal insufficiency due to reduce nitrogen-related products in serum. The present study investigated the pharmacokinetics of lactulose, its removal rate through dialysis, and safety by administering lactulose 6.5 g (Lagnos Jelly Divided Pack 16.05 g) orally to six hemodialysis patients who resided in Taiwan. As a result, the means of maximum plasma concentrations (C_max) and Time to reach C_max (Tmax) were 3090 ± 970 ng/mL and 6.5 ± 2.3 hours, respectively. The mean plasma concentration was 2220 ± 986 ng/mL after administration for 24 hours. Sequentially, the mean plasma concentration reduced to 307 ± 117 ng/mL after the application of 4-hour dialysis. Area under the plasma concentration-time curve from zero to 24 h post-dose (AUC_0–24h) were 56,200 ± 21,300 ng h/mL and the AUC_0–28h was 61,200 ± 23,300 ng h/mL. The rate of lactulose removal by dialysis was 83.6 ± 8.9%. In addition, the multiple doses of lactulose using a simulated model suggested that no plasma accumulation would be expected while coordinating with dialysis. Good tolerability was confirmed, while the mild adverse effect of diarrhea was observed in one case during the study period. No death or serious adverse effect was reported. Based on the present study, we demonstrated the pharmacokinetic transition with respect to plasma levels of lactulose in patients with impaired renal excretion treated with hemodialysis.

Effects of Sevelamer Hydrochloride on Uremic Toxins Serum Indoxyl Sulfate and P-Cresyl Sulfate in Hemodialysis Patients

Background

Beside the phosphate binding effect, non-calcium non-aluminum phosphate binder, namely sevelamer hydrochloride (SH), has many other effects in dialysis patients. It can absorb many other compounds, decrease low-density lipoprotein cholesterol (LDL-C) level, and attenuate the progression of vascular calcification; it has been reported to have anti-inflammatory effect. However, it is not clear whether it has any effect on uremic toxins, i.e. serum indoxyl sulfate (IS) and p-cresyl sulfate, (PCS) in hemodialysis (HD) patients. This study was carried out to appraise the effect of sevelamer on serum IS and PCS in HD patients.

Methods

Five adult HD patients from a single medical center were enrolled in this study; these patients were treated with 800 mg of sevelamer thrice per day for 3 months; a series of biochemical parameters, serum IS and PCS were monitored concurrently.

Results

There was a significant reduction in the mean level of phosphate from 7.20 ± 0.70 mg/dL (mean ± SD) before treatment to 5.40 ± 0.50 mg/dL (mean ± SD) after treatment, total cholesterol from 151.00 ± 37.40 mg/dL (mean ± SD) before treatment to 119.20 ± 29.40 mg/dL (mean ± SD) after treatment, and PCS from 31.30 ± 10.60 mg/L (mean ± SD) before treatment to 19.70 ± 10.50 mg/L (mean ± SD) after treatment. On the contrary, this treatment had no effect on IS.

Conclusion

A statistically significant reduction of serum phosphate and PCS in HD patients treated with SH suggests that beside the action of lowering serum phosphate, sevelamer may have an important role in the treatment of uremic syndrome by decreasing the uremic toxin.

The Role of Liver in Determining Serum Colon-Derived Uremic Solutes

Evidence has shown that indoxyl sulfate (IS) and p-cresyl sulfate (PCS) may be alternative predictors of clinical outcomes in chronic kidney disease (CKD). Both toxins are derived from the gastrointestinal tract and metabolised in the liver. However, it is unclear whether the liver affects the production of IS and PCS. Here, we explore the association between IS and PCS levels in liver cirrhosis and a CKD-based cohort (N = 115). Liver and kidney function was assessed and classified by a Child-Pugh score (child A–C) and a modified version of the Modification of Diet in Renal Disease (MDRD) equation (Stages 1–4), respectively. An animal model was also used to confirm the two toxin levels in a case of liver fibrosis. In patients with early liver cirrhosis (child A), IS and PCS were significantly associated with CKD stages. In contrast, serum IS and PCS did not significantly change in advanced liver cirrhosis (child C). A stepwise multiple linear regression analysis also showed that T-PCS was significantly associated with stages of liver cirrhosis after adjusting for other confounding factors (B = -2.29, p = 0.012). Moreover, the serum and urine levels of T-PCS and T-IS were significantly lower in rats with liver failure than in those without (p<0.01, p<0.05 and p<0.01, p<0.05, respectively). These results indicated that in addition to the kidneys, the liver was an essential and independent organ in determining serum IS and PCS levels. The production rate of IS and PCS was lower in patients with advanced liver cirrhosis.

Bicarbonate can improve the prognostic value of the MELD score for critically ill patients with cirrhosis

The prognosis of critically ill patients with cirrhosis is poor. Our aim was to identify an objective variable that can improve the prognostic value of the Model of End-Stage Liver Disease (MELD) score in patients who have cirrhosis and are admitted to the intensive care unit (ICU). This retrospective cohort study included 177 patients who had liver cirrhosis and were admitted to the ICU. Data pertaining to arterial blood gas-related parameters and other variables were obtained on the day of ICU admission. The overall ICU mortality rate was 36.2%. The bicarbonate (HCO3) level was found to be an independent predictor of ICU mortality (odds ratio, 2.3; 95% confidence interval [CI], 1.0-4.8; p = 0.038). A new equation was constructed (MELD-Bicarbonate) by replacing total bilirubin by HCO3 in the original MELD score. The area under the receiver operating characteristic curve for predicting ICU mortality was 0.76 (95% CI, 0.69-0.84) for the MELD-Bicarbonate equation, 0.73 (95% CI, 0.65-0.81) for the MELD score, and 0.71 (95% CI, 0.63-0.80) for the Acute Physiology and Chronic Health Evaluation II score. Bicarbonate level assessment, as an objective and reproducible laboratory test, has significant predictive value in critically ill patients with cirrhosis. In contrast, the predictive value of total bilirubin is not as prominent in this setting. The MELD-Bicarbonate equation, which included three variables (international normalized ratio, creatinine level, and HCO3 level), showed better prognostic value than the original MELD score in critically ill patients with cirrhosis.

Effects of age and diabetes mellitus on clinical outcomes in patients with peritoneal dialysis-related peritonitis

BACKGROUND

Peritoneal dialysis (PD)-related peritonitis is the most common complication and the leading cause of technique failure for patients on PD therapy. The aim of this study was to review the episodes and outcomes of PD-related peritonitis, with special reference to the effects of age and diabetes status.

METHODS

The study comprised 204 consecutive peritonitis episodes between January 2001 and June 2011 from our registry database. Factors associated with treatment failure and mortality were analyzed with multi-variable logistic regression modeling.

RESULTS

The overall peritonitis rate was one episode per 65 patient-months or 0.187 episodes/patient-year. Older patients had lower probability of remaining free of peritonitis (log rank, p<0.001). Elderly patients and diabetic subjects had a higher risk of peritonitis-related dropout. Age (odds ratio [OR], 1.37; p=0.041), diabetes mellitus (OR, 3.64; p=0.005), and gram-negative peritonitis (OR, 3.55; p=0.011) were independent determinants of catheter removal. Age (OR, 1.93; p=0.026) and diabetes (OR, 5.98; p=0.015) were the only predictors of death from peritonitis.

CONCLUSIONS

Old age and diabetes mellitus are two major risk factors for adverse outcomes of PD-related peritonitis. Although they are not contraindications to PD, our results suggest that these patients need meticulous care when peritonitis occurs.

Serum p-cresyl sulfate predicts cardiovascular disease and mortality in elderly hemodialysis patients

INTRODUCTION

Previous studies have shown that serum p-cresyl sulfate (PCS) and indoxyl sulfate (IS) were significantly related to clinical outcomes in patients on hemodialysis (HD). However, evidence for the relationship in elderly HD patients remains scarce. We explore whether the two toxins can predict clinical outcomes in elderly HD patients.

MATERIAL AND METHODS

Fifty stable HD patients more than 65 years old were enrolled from a single medical center. Serum total and free PCS, IS levels and biochemistry were measured concurrently. The clinical outcomes including cardiovascular events and all-cause mortality were analyzed after 38-month follow-up.

RESULTS

Univariate Cox proportional hazard ratio analysis revealed that cardiovascular events were associated with gender (p = 0.02), diabetes (p < 0.01), calcium (p = 0.01), total PCS (p < 0.01), free PCS (p < 0.01) and total IS (p = 0.05). Multivariate analysis showed that diabetes (p = 0.01), total PCS (p = 0.01) and free PCS (p = 0.04) were related to cardiovascular events. For all-cause mortality, only total PCS (p = 0.01) reached significance after adjusting other confounding factors. However, Kaplan-Meier analysis indicated that free PCS (p = 0.02) and total PCS (p < 0.01) were significantly associated with cardiovascular events and total PCS (p = 0.048) was related to all-cause mortality during 38-month follow-up.

CONCLUSIONS

Our results indicate that total PCS is a valuable marker in predicting cardiovascular event and all-cause mortality in elderly HD patients.

Peripheral artery disease in peritoneal dialysis and hemodialysis patients: single-center retrospective study in Taiwan

Background

Peripheral artery disease (PAD) is a condition characterized by restricted blood flow to the extremities, and is especially common in the elderly. PAD increases the risk for mortality and morbidity in patients with end-stage renal disease (ESRD), especially those on hemodialysis (HD).

Methods

The records of 484 patients with end-stage renal disease who were on HD or peritoneal dialysis (PD) were reviewed. PAD was diagnosed based on the ankle-brachial pressure index (ABI). Demographic and clinical characteristics were analyzed.

Results

PAD had an overall prevalence of 18.2% and was significantly more common in HD patients (21.8%) than in PD patients (4.8%). Advanced age, diabetes mellitus, smoking, low parathyroid hormone level, elevated serum ferritin, elevated serum glucose, and low serum creatinine levels increased the risk for PAD. PAD was independently associated with advanced age, diabetes mellitus, duration of dialysis, low serum creatinine, and hyperlipidemia. PD patients had a significantly lower prevalence of PAD than HD patients, maybe due to their younger age and lower prevalence of diabetes mellitus in this present study.

Conclusions

The prevalence of PAD was greater in the HD group than the PD group. Most of the risk factors for PAD were specific to HD, and no analyzed factor was significantly associated with PAD in PD patients.

The role of protein-bound uremic toxins on peripheral artery disease and vascular access failure in patients on hemodialysis

OBJECTIVE

p-Cresyl sulfate (PCS) and indoxyl sulfate (IS) have been reported to predict poor clinical outcomes in hemodialysis (HD) patients. However, little is known about the effect of the two toxins on peripheral arterial disease (PAD) and vascular access dysfunction. Our objective was to explore the association between the two toxins and PAD and vascular access failure (VAF) in a hemodialysis-based cohort.

METHODS

We enrolled 100 stable and eligible HD patients from a single medical center. These patients were screened for PAD by machine and recorded as ABI (ankle brachial index) and brachial-ankle PWV (pulse wave velocity). Serum levels of PCS, IS and biochemical data were also collected concurrently. In addition, we also recorded the first event of VAF and frequency of PTA and thrombectomy during 3-year follow-up.

RESULTS

Total and free PCS were correlated to right and left ABI and PWV (p < 0.01), and total IS was associated with right and left ABI (p < 0.01) by Pearson's analysis. Repeated measuring by mixed model analysis revealed that serum albumin (p = 0.003), cholesterol (p = 0.01) and total PCS (p = 0.031) had significant correlation with ABI after adjusting other confounding factors. As for brachial-ankle PWV, serum triglyceride (p = 0.002), total IS (p = 0.04) and total PCS (p = 0.050) reached significance finally. In addition, multivariate Cox regression analysis revealed dialysis length and total PCS were related to AV-shunt failure event (Hazard Ratio: 1.14, p = 0.01, and Hazard Ratio: 1.04, p = 0.04, respectively). Both of total and free PCS and IS were also positively linked to numbers of PTA and thrombectomy. Further, the Kaplan-Meier analysis showed only total PCS was significantly associated with vascular access failure event (log rank P = 0.02).

CONCLUSION

This study shows that the serum levels of PCS and IS were associated with PAD and total PCS could be a valuable determinant of access viability other than traditional or nontraditional risk factors in HD patients.

Absolute interdialytic weight gain is more important than percent weight gain for intradialytic hypotension in heavy patients

AIM

Few published reports have mentioned the difference between absolute interdialytic weight gain (IDWG) and IDWG/DW (IDWG%), and subsequent effects on daily dialysis. The aim of present study was to evaluate the difference between absolute IDWG and IDWG% in new haemodialysis patients.

METHOD

We retrospectively reviewed the records of 255 patients who recently received conventional haemodialysis for at least 1 year at the same centre from 1997 to 2008. The first 4 weeks after starting haemodialysis was defined as the pre-study period. Data were collected for 5-56 weeks.

RESULTS

IDWG% value remained relatively constant in the first year of haemodialysis despite most patients having certain residual renal function. For haemodialysis outcomes, both absolute IDWG and IDWG% were significantly correlated with intradialytic hypotension (IDH) in men and heavy women. After dividing patients into four strata, which according to the gender and the median dry weight, stepwise multivariate linear regression analysis showed that absolute IDWG, rather than IDWG%, was an independent risk factor for IDH in heavy men (Beta = 0.585, P < 0.001) and heavy women (Beta= 0.458, P < 0.001).

CONCLUSIONS

Absolute IDWG, rather than IDWG%, is an independent risk factor for IDH in heavy haemodialysis patients. Therefore, higher absolute IDWG needs to be strictly controlled despite the corresponding IDWG% possibly being relatively small in heavy haemodialysis patients.

p-Cresylsulfate and indoxyl sulfate level at different stages of chronic kidney disease

Indoxyl sulfate and p-cresylsulfate was associated with poor clinical outcome of uremia. We explored the relationship between the two toxins and renal function in chronic kidney disease (CKD) patients. This study enrolled 103 stable CKD patients (stage 3-5 and hemodialysis (HD) patients). Serum levels of indoxyl sulfate and p-cresylsulfate were measured using ultra performance liquid chromatography. General laboratory results and patient background were also checked. Patients with advanced CKD had higher serum indoxyl sulfate, p-cresylsulfate based on ANOVA test. There were significant correlation between indoxyl sulfate and p-cresylsulfate and serum creatinine after multivariate regression analysis (B=3.59, P<0.01; B=0.93, P=0.04, respectively). In addition, there was a positive correlation between indoxyl sulfate and p-cresylsulfate level (r=0.61, P<0.01). Indoxyl sulfate and p-cresylsulfate level increased gradually while renal function declined and reached the peak at the stage of HD. Serum indoxyl sulfate level was closely associated with p-cresylsulfate level in CKD patients.

The characteristics of new semi-quantitative method for diagnosing proteinuria by using random urine samples

We assessed the characteristics of the new semi-quantitative test paper (Clinitek ATLAS Pro(12)) using random urine samples. Three hundred urine samples were analyzed using either the new test paper, conventional dipsticks, quantitative (P/C ratio), or immunological quantitative methods (A/C ratio). Our study showed that the new test paper is highly sensitive and specific for the detection of urinary protein. The new test paper also detected the urine protein more accurately than the conventional test and has a lower false-positive rate. In addition, the new test paper detected 14 of the 300 patients (4.7%) as dilute urine samples needing reassessment. Seventeen of the 300 samples tested were negative with conventional dipsticks but positive with the new test paper. The new semi-quantitative test paper not only has higher sensitivity than the conventional dipstick method, but also has potential to detect dilute samples.

Serum protein-bound uraemic toxins and clinical outcomes in haemodialysis patients

BACKGROUND

The protein-bound uraemic toxin p-cresol is associated with immunodeficiency in haemodialysis (HD) patients. We investigated the effect of serum p-cresol, indoxyl sulphate and other variables on clinical outcomes in HD patients during a 20-month follow-up.

METHODS

We enrolled 100 stable HD patients from a single medical centre. The primary outcomes were infection-related hospitalization, cardiovascular events and all-cause mortality. Serum total and free p-cresol and indoxyl sulphate levels were measured using ultra-performance liquid chromatography. Biochemical data were collected concurrently.

RESULTS

Multivariate logistic regression analysis revealed that infection-related hospitalization correlated with free p-cresol (adjusted odds ratio: 1.70, P = 0.01) and highly sensitive C-reactive protein (hsCRP) (adjusted odds ratio: 2.07, P = 0.01); cardiovascular event was associated with free p-cresol (adjusted odds ratio: 1.78, P = 0.01) and nPCR (adjusted odds ratio: 0.01, P = 0.02); and all-cause mortality was related to albumin (adjusted odds ratio: 0.04, P = 0.01). The Kaplan-Meier method showed that free and total p-cresol were significantly associated with cardiovascular events (log-rank P < 0.01 and log-rank P < 0.01, respectively). Serum free p-cresol seemed to have a trend to correlate with infection-related hospitalization during a 20-month follow-up (log-rank P = 0.05).

CONCLUSIONS

Serum free and total p-cresol levels were significantly related to cardiovascular events. In addition, serum free p-cresol and hsCRP levels were also found to be associated with infection-related hospitalization.

Inhibitory mechanisms of gabapentin, an antiseizure drug, on platelet aggregation

Gabapentin (Neurontin) is an analogue of gamma-aminobutyric acid (GABA) that is effective against partial seizures. Gabapentin has been reported to modulate serotonin release from platelets, but the effects of gabapentin on platelet activation have not been explored. In this study, gabapentin concentration-dependently (60–240 μm) inhibited platelet aggregation in washed platelets stimulated by collagen (1 μg mL−1), ADP (20 μm) and arachidonic acid (60 μm). Gabapentin (120 and 240 μm) also concentration-dependently inhibited collagen (1 μg mL−1)-induced phospho-inositide breakdown, intracellular Ca2+ mobilization, thromboxane A2 formation, and p38 MAPK phosphorylation in human platelets. In conclusion, the most important findings of this study suggest that gabapentin inhibits platelet aggregation, at least in part, through the phospholipase C-inositol 1,4,5-trisphosphate-thromboxane A2-Ca2+ pathway. Thus, it is possible that gabapentin treatment, alone or in combination with other antiplatelet drugs, may induce or potentiate inhibition of platelet aggregation, which may affect haemostasis in-vivo.

Molecular analysis of HLA-DRB1 allelic associations with systemic lupus erythematous and lupus nephritis in Taiwan

To evaluate the association of human leukocyte antigen (HLA)–DRB1 alleles with systemic lupus erythematosus (SLE) and lupus nephritis (LN) in the Taiwanese population, and to investigate the possible association of HLA-DRB1 alleles with disease severity in LN. HLA-DRB1 alleles were studied in 105 SLE patients (82 patients with LN, 23 patients without LN) and 855 healthy controls by polymerase chain reaction and sequence-based typing assays. The frequency of the HLA class II alleles DRB1*0301 (Odds ratio [OR] = 2.01, 95% confidence interval [CI] = 1.31–3.10, Pc = 0.02) and DRB1*1501 (OR = 2.06, 95% CI = 1.36–3.13, Pc = 0.01) were both increased in SLE patients, compared to healthy controls. The frequency of DRB1*1202 was significantly lower in LN patients than in SLE patients without nephritis (OR = 0.23, 95% CI = 0.09–0.57, Pc = 0.01). No specific allele was significantly associated with an increased or decreased risk for severity of LN in this sample. In Taiwanese people, the DRB1*0301 and DRB1*1501 alleles are significant risk factors for SLE, while the DRB1*1202 allele is protective for LN.

CYP17 genotype and breast cancer risk

The MspAI polymorphism in the 5' untranslated region of CYP17 has been evaluated as a breast cancer risk factor in a hospital-based case-control study in New York City. The study population consisted of 363 women [123 breast cancer patients and 240 patient controls (123 benign breast disease without atypical hyperplasia, 117 women without breast disease)]. There were 224 Caucasians (76 cases, 148 controls), 55 African-Americans (20 cases, 35 controls) and 84 Hispanics (27 cases, 57 controls); 142 premenopausal women and 221 postmenopausal women. Consistent with a previous report (Feigelson et al., Cancer Res., 57: 1063-1065, 1997) we found no evidence to implicate the minor variant (restriction site present allele, designated A2) as a breast cancer risk factor. Furthermore, we sought evidence to implicate the minor variant of CYP17 in the development of more aggressive breast cancers (n = 38/121) as had been reported previously. Although confidence intervals (CI) overlap, the data presented here do not provide support for previously reported findings (odds ratio, 0.9; 95% CI, 0.4-2.0; n = 38 versus odds ratio, 2.5; 95% CI, 1.1-5.2; n = 40). Clearly this question needs to be resolved in a larger study. No evidence was found to support the contention that inheritance of the minor variant is a predictor of early age at menarche. Allelic frequencies between different ethnic groups were not found to be different with the exception of Hispanic controls, in which the genotypic distribution was not consistent with the Hardy-Weinberg equilibrium.

Biomonitoring of United States Army soldiers serving in Kuwait in 1991

Biomarkers of polycyclic aromatic hydrocarbon (PAH) exposure and genetic biomarkers of potential cancer susceptibility were determined in a group of United States Army soldiers who were deployed to Kuwait and Saudi Arabia in 1991 in the aftermath of the Persian Gulf War. Because hundreds of oil well fires were still burning, there was concern that ground troops stationed in Kuwait might be exposed to high levels of PAHs and other toxicants. The United States Army Environmental Hygiene Agency monitored air and soil for ambient PAHs. In addition, a group of 61 soldiers was involved in the biomonitoring study reported here. These soldiers kept diaries of daily activities and provided blood and urine samples in Germany (June) before deployment to Kuwait, after 8 weeks in Kuwait (August), and 1 month after the return to Germany (October). Here we present data for PAH-DNA adducts measured by immunoassay in blood cell DNA samples obtained at all three sampling times from 22 soldiers and bulky aromatic adducts measured by 32P-postlabeling in blood cell DNA samples from 20 of the same soldiers. Urinary 1-hydroxypyrene-glucuronide levels were determined by synchronous fluorescence spectrometry in a matched set of samples from 33 soldiers. Contrary to expectations, environmental monitoring showed low ambient PAH levels in the areas where these soldiers were working in Kuwait. For both DNA adduct assays, levels were the lowest in Kuwait in August and increased significantly after the soldiers returned to Germany (October). Urinary 1-hydroxypyrene-glucuronide levels were also lowest in Kuwait and highest in Germany, but the differences were not statistically significant. The PAH-exposure biomarker levels were not significantly influenced by polymorphic variations of CYP1A1 (MspI) and glutathione S-transferases M1 and T1. Overall, the data suggest that this group of soldiers was not exposed to elevated levels of PAHs while deployed in Kuwait.

Urinary excretion of 1-hydroxypyrene as a marker for exposure to urban air levels of polycyclic aromatic hydrocarbons

A cross-sectional study was conducted among 94 traffic police officers from the Municipality Police of Genoa, Italy, exposed to airborne pollutants and 52 referent subjects exposed to indoor air pollution levels to investigate the relationships between exposure to ambient air polycyclic aromatic hydrocarbons (PAHs) and urinary excretion of 1-hydroxypyrene (1-OH-P). The effects of smoking, lifestyle factors such as exposure to ETS, and diet, along with the role played by the cytochrome P4501A1 (CYP1A1), and glutathione S-transferase M1 and theta metabolic susceptibility gene polymorphisms were examined. The geometric mean of benzo(a)pyrene air measurements (an index compound of PAH levels) was 70 times higher in traffic police officers (3.67 ng/m3) than in referents (0.05 ng/m3). The urinary concentration of 1-OH-P was clearly associated with cigarette smoking and, to a lesser extent, with exposure to ETS and particulate PAH pollution. No association was detected between 1-OH-P excretion and diet. Women exhibited a higher excretion level than did men, and an apparent effect of age was due to differences in cigarette smoking habits. Exposure to PAHs resulted in higher levels of 1-OH-P excretion in all groups except heavy smokers. Overall, no significant role of any metabolic polymorphism was detected. However, stratification of study subjects according to their smoking habits revealed higher levels of excretion of 1-OH-P in subjects smoking < or =15 cigarettes/day carrying the CYP1A1 polymorphism. No such effect was seen either with nonsmokers or with people smoking more than 15 cigarettes/day. These findings are suggestive of a gene-environment interaction, in which subjects with the CYP1A1 polymorphism, relative to subjects without it, have higher levels of 1-OH-P in their urine at low doses of exposure to PAHs.

The effects of enzyme and inorganic phosphorus supplements in wheat- and rye-based diets on laying hen performance, energy, and phosphorus availability

A total of 640 22-wk-old pullets (Shaver SX 288) housed four birds per cage in 40 experimental units (four cages per unit), were randomly assigned eight experimental diets in a 2 x 2 x 2 factorial arrangement. The treatments consisting of two grain sources (wheat and rye) two levels each of crude enzyme preparation (0 and 0.1% Roxazyme G), and added inorganic phosphorus (0 and 0.105%) were fed for five 4-wk periods. At 42 wk of age, 40 individually caged layers were fed the experimental diets with 0.3% chromic oxide (5 individual birds per treatment) to determine AMEn and available P. Plasma P and Ca were also determined. Egg production, feed intake (FI), egg weight, feed efficiency (FE), and specific gravity of eggs were significantly (P < or = 0.05) affected by the experimental periods. Hens fed wheat-based diets had higher (P < or = 0.05) tibia ash (54.3 vs 52.5%), excreta dry matter (22.0 vs 17.7%), and eggshells with > or = 1.080 specific gravity (93.5 vs 89.9%) than birds fed rye. Enzyme supplementation significantly improved AMEn (P < or = 0.01) and FE by 6.2 and 3%, respectively. Egg production increased numerically from 87.6 to 90.1%. Inorganic P supplementation significantly increased egg production (P < or = 0.01), FI, FE, and AMEn (P < or = 0.05) by 4.4, 2, 3, and 2.8%, respectively, but significantly (P < or = 0.05) decreased the proportion of eggs having a specific gravity > or = 1.080 from 92.8 to 90.6%. The enzyme and inorganic P supplementation had no effect on tibia ash content and total plasma Ca and P. Rye can be used in layer rations yielding satisfactory performance when fed with a fungal crude enzyme preparation high in pentosanase/xylanase activity.

p53 haplotype determination in breast cancer

Inheritance of certain germ line haplotypes consisting of three biallelic polymorphisms of p53 has been proposed as a risk factor for breast cancer and colorectal cancer [A. Själander et al., Carcinogenesis (Lond.), 17: 1313-1316, 1996, and Carcinogenesis (Lond.), 16: 1461-1464, 1995]. In their studies, pairwise haplotypes of these three polymorphisms were estimated. Extended haplotypes were further projected from the pairwise combinations. To overcome the necessity to estimate pairwise and extended haplotype frequencies, a PCR method has been developed to determine the absolute extended p53 haplotypes in diploid genomes. The method requires allele-specific PCR, confirmed by restriction analysis, and successive amplicon analysis. It has been applied to a nested case-control study of breast cancer (284 subjects; 99 cases and 185 controls; 182 Caucasians, 56 Hispanics, and 46 African-Americans). Evidence is presented that minor variants of the intron 3, codon 72, and intron 6 polymorphisms were moderately elevated in Caucasian breast cancer cases (intron 3, P = 0.03 for genotype and P = 0.01 for allelic frequency; codon 72, P = 0.07 for genotype and P = 0.054 for allelic frequency; and intron 6, P = 0.02 for genotype and P = 0.02 for allele frequency). Accordingly, analysis of haplotype distributions suggested an association of minor p53 haplotypes with breast cancer risk in Caucasians (P = 0.07). The relative allelic frequencies in breast cancer cases compared with controls also differed by age and menopausal status; the 1-2-1 haplotype was overrepresented in postmenopausal cases (P = 0.02) and cases older than 50 years (P = 0.02), whereas the other minor haplotypes (1-1-2 and rare variants) were overrepresented in premenopausal cases (P = 0.003) and cases 50 years of age and younger (P = 0.02). Genotype distributions at each locus and for all control groups were consistent with Hardy-Weinberg equilibria. Differences in haplotype distribution were associated with ethnicity (Caucasians versus African-Americans and Caucasians versus Hispanics, P < 0.001). The new haplotyping method may be useful in the study of gene-environment interactions.