Rate of Synthetic Oligosaccharide Degradation as a Novel Measure of Amylase Activity in Peritoneal Dialysis Patients

2008 ◽  
Vol 28 (3) ◽  
pp. 296-304 ◽  
Author(s):  
Elvia García–López ◽  
Andrzej Werynski ◽  
Olof Heimbürger ◽  
José C. Divino Filho ◽  
Bengt Lindholm ◽  
...  
Keyword(s):  
Peritoneal Dialysis ◽  
Amylase Activity ◽  
Ex Vivo ◽  
Total Activity ◽  
Activity Level ◽  
Dialysis Patients ◽  
Ex Vivo Model ◽  
Patient Groups ◽  
Uremic Patients ◽  
The Relationship

Background Plasma α–amylase activity is elevated in uremic patients but lower in peritoneal dialysis (PD) patients using icodextrin in comparison to healthy controls. We studied the rate by which an exogenous oligosaccharide (maltoheptaose; G7) is degraded ex vivo by amylase in plasma from PD patients treated with glucose or icodextrin PD solutions. Methods Plasma amylase (pancreatic and total) activity and concentration were measured in 11 controls and in PD patients treated with glucose ( n = 11) and icodextrin ( n = 19). The plasma was spiked with G7 and/or synthetic amylase and the metabolites formed were measured by HPLC following incubation at 37°C for 4 hours. Results The relationship between amylase activity and amylase concentration was similar in all patients and controls. The G7 degradation rate was slower in plasma from icodextrin patients but it was also reduced in patients using glucose compared with the controls, in spite of the higher amylase activity in the glucose group. Normalization (by spiking) of patient plasma with porcine amylase increased but did not normalize the speed of G7 degradation. At a given endogenous amylase activity level, the efficiency of G7 degradation was similar for both patient groups. Conclusions An ex vivo model to study the relationship between amylase activity and the actual rate of carbohydrate (represented by G7) breakdown was developed and showed that PD patients using glucose and icodextrin degrade G7 at a slower speed than controls. This suggests that amylase-mediated carbohydrate metabolism is reduced in PD patients. Further clinical studies are needed to confirm if these findings hold true also in other groups of uremic patients with varying degrees of kidney failure, as well as in patients undergoing hemodialysis.

Alterations of nitric oxide synthase expression and activity during rat lung transplantation

2000 ◽  
Vol 278 (5) ◽  
pp. L1071-L1081 ◽  
Author(s):  
Mingyao Liu ◽  
Lorraine Tremblay ◽  
Stephen D. Cassivi ◽  
Xiao-Hui Bai ◽  
Eric Mourgeon ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Lung Transplantation ◽  
Ex Vivo ◽  
Total Activity ◽  
No Production ◽  
Ex Vivo Model ◽  
Gene And Protein Expression ◽  
Lung Transplants ◽  
Inducible Nos

Decreased nitric oxide (NO) production has been reported during lung transplantation in patients. To study the effects of ischemia and reperfusion on endogenous NO synthase (NOS) expression, both an ex vivo and an in vivo lung injury model for transplantation were used. Donor rat lungs were flushed with cold low-potassium dextran solution and subjected to either cold (4°C for 12 h) or warm (21°C for 4 h) ischemic preservation followed by reperfusion with an ex vivo model. A significant increase in inducible NOS and a decrease in endothelial NOS mRNA was found after reperfusion. These results were confirmed in a rat single-lung transplant model after warm preservation. Interestingly, protein contents of both inducible NOS and endothelial NOS increased in the transplanted lung after 2 h of reperfusion. However, the total activity of NOS in the transplanted lungs remained at very low levels. We conclude that ischemic lung preservation and reperfusion result in altered NOS gene and protein expression with inhibited NOS activity, which may contribute to the injury of lung transplants.

scholarly journals Clinical indices of in vivo biocompatibility: The role of ex vivo cell function studies and effluent markers in peritoneal dialysis patients

2003 ◽  
Vol 64 ◽  
pp. S84-S93 ◽  
Author(s):  
Ruth Mackenzie ◽  
Clifford J. Holmes ◽  
Suzanne Jones ◽  
John D. Williams ◽  
Nicholas Topley
Keyword(s):  
Peritoneal Dialysis ◽  
Cell Function ◽  
Ex Vivo ◽  
Dialysis Patients ◽  
Clinical Indices

The Relationship between Kt/VUrea and Npna in Anuric Peritoneal Dialysis Patients: A Comparison with Predialysis Patients

2001 ◽  
Vol 21 (5) ◽  
pp. 509-515 ◽  
Author(s):  
◽  
Maarten A.M. Jansen ◽  
Johanna C. Korevaar ◽  
Friedo W. Dekker ◽  
Kitty J. Jager ◽  
...  
Keyword(s):  
Renal Function ◽  
Peritoneal Dialysis ◽  
Residual Renal Function ◽  
Control Group ◽  
Dialysis Patients ◽  
Urea Clearance ◽  
Linear Relationships ◽  
Significant Difference ◽  
Urine Production ◽  
The Relationship

Objective It is unknown whether a given level of urea clearance by the native kidneys provides better or similar control of uremia than the same level of urea clearance by continuous peritoneal dialysis (PD). More insight into possible differences between renal and peritoneal urea clearances is warranted. Therefore, we investigated the relationship between Kt/Vurea and protein equivalent of total nitrogen appearance normalized to body weight (nPNA), the relationship between urea clearance and creatinine appearance, and other nutritional parameters in PD patients without residual renal function, and in predialysis end-stage renal disease patients. Patients All patients participated in the Netherlands Cooperative Study on the Adequacy of Dialysis. This is a prospective cohort study of incident dialysis patients, in whom regular assessments of renal function are done. A group of 75 PD patients was identified at the first follow-up assessment in which their urine production was less than 100 mL/day. These patients were considered the anuric group. This group was compared with a control group of 97 predialysis patients studied 0 – 4 weeks before the start of dialysis treatment. Results Linear relationships were present between Kt/Vurea and nPNA, in both the predialysis patients and the anuric PD patients. A significant difference was present between the slopes of the two regression lines (0.40 vs 0.18, p = 0.007). When Kt/Vurea exceeded 1.3/week, a given level of Kt/Vurea was associated with a higher nPNA in predialysis than in anuric PD patients. Similar relationships were found between Kturea and PNA. Kturea was also significantly related to urine or dialysate creatinine appearance. A significant difference existed between the slopes of the regression lines in the two groups of patients ( p < 0.001). A weekly Kturea of 70 L was associated with a urine creatinine appearance of 11.0 mmol/day and a dialysate creatinine appearance of 8.4 mmol/day. Nutritional status measured with creatinine appearance and Subjective Global Assessment was better in the predialysis population, despite much lower values for Kt/Vurea in these patients. Conclusions The relationship between Kt/Vurea and nPNA in anuric PD patients is different from that in a predialysis population. It follows from our results that, when Kt/Vurea is above 1.3/week, a given level of Kt/Vurea is associated with a higher nPNA in predialysis than in anuric PD patients. This challenges the concept of equivalency between renal and peritoneal Kt/Vurea with respect to control of uremic morbidity.

Icodextrin Metabolism and Alpha-Amylase Activity in Nonuremic Rats Undergoing Chronic Peritoneal Dialysis

2007 ◽  
Vol 27 (4) ◽  
pp. 415-423 ◽  
Author(s):  
Elvia García–López ◽  
Krzysztof Pawlaczyk ◽  
Björn Anderstam ◽  
A. Rashid Qureshi ◽  
Malgorzata Kuzlan–Pawlaczyk ◽  
...  
Keyword(s):  
Peritoneal Dialysis ◽  
Peritoneal Cavity ◽  
Wistar Rats ◽  
Amylase Activity ◽  
Dialysis Fluid ◽  
Dialysis Patients ◽  
Peritoneal Dialysis Fluid ◽  
Male Wistar Rats ◽  
Osmotic Agent ◽  
Dialysis Solutions

Objective To study the metabolism of icodextrin and α–amylase activity following daily exposure to dialysis solutions containing either glucose or icodextrin as osmotic agent in rats. Methods Male Wistar rats with implanted peritoneal catheters were infused twice daily for 3 weeks with 20 mL 7.5% icodextrin-based peritoneal dialysis fluid (IPDF; ICO group, n = 12) or 3.86% glucose-based peritoneal dialysis fluid (GLU group, n = 11). A 4-hour dwell study using 30 mL IPDF was performed on day 10 (D1) and day 21 (D2) in both the ICO and the GLU groups. Radiolabeled serum albumin (RISA) was used as a macromolecular volume marker. Dialysate samples were collected at 3, 15, 30, 60, 90, 120, and 240 minutes. Blood samples were drawn before the start and at the end of the dwell. Results During all dwell studies, the dialysate concentrations of total icodextrin decreased due to decrease in high molecular weight (MW) fractions, whereas there was a marked increase in icodextrin low MW metabolites. α–Amylase activity increased in dialysate and decreased in plasma. About 60% of the total icodextrin was absorbed from the peritoneal cavity during the 4-hour dwells. Low MW icodextrin metabolites were present in the dialysate already at 3 minutes, and maltose (G2), maltotriose (G3), maltotetraose (G4), and maltopentaose (G5) increased progressively, reaching maximum concentrations at 60 minutes. Maltohexaose (G6) and maltoheptaose (G7) were also detected already at 3 minutes but did not change significantly during the dwells. During the two 4-hour dwell studies (D1 and D2), the concentrations of total icodextrin and icodextrin metabolites and α–amylase activity in dialysate did not differ between the ICO and GLU groups, during either D1 or D2. No icodextrin metabolites were detected in plasma at the end of the dwells. α–Amylase activity in the dialysate increased six- to eightfold whereas plasma α–amylase activity decreased by 21% – 26% during the two 4-hour dwells in both the ICO and the GLU groups; there were no significant differences between the ICO and the GLU groups during either D1 or D2. α–Amylase activity in the dialysate correlated strongly with the disappearance rate of icodextrin from the peritoneal cavity during the 4-hour dwells, and with the concentrations of G2, G3, G6, and G7 in dialysate. Conclusions The decline in the dialysate concentrations of high MW fractions and the increase in low MW metabolites of icodextrin suggest intraperitoneal α–amylase mediated the metabolism of icodextrin and the transport of predominantly the smaller icodextrin metabolites from dialysate. However, no icodextrin could be detected in plasma, suggesting that it was metabolized and excreted by the kidney in these nonuremic rats. In contrast to uremic peritoneal dialysis patients, chronic exposure to IPDF did not seem to further affect α–amylase activity or icodextrin metabolism. The much higher α–amylase activity in plasma and dialysate in rats than in humans explains the much more rapid metabolism of icodextrin in rats compared with peritoneal dialysis patients.

scholarly journals Racial and Ethnic Differences in Mortality Associated with Serum Potassium in Incident Peritoneal Dialysis Patients

2019 ◽  
Vol 50 (5) ◽  
pp. 361-369 ◽  
Author(s):  
Rieko Eriguchi ◽  
Yoshitsugu Obi ◽  
Melissa Soohoo ◽  
Connie M. Rhee ◽  
Csaba P. Kovesdy ◽  
...  
Keyword(s):  
Peritoneal Dialysis ◽  
Serum Potassium ◽  
Dialysis Patients ◽  
Cox Models ◽  
Baseline Serum ◽  
Racial And Ethnic Differences ◽  
Hispanic Patients ◽  
Race Ethnicity ◽  
The Relationship ◽  
Related Mortality

Background: Abnormalities in serum potassium are risk factors for sudden cardiac death and arrhythmias among dialysis patients. Although a previous study in hemodialysis patients has shown that race/ethnicity may impact the relationship between serum potassium and mortality, the relationship remains unclear among peritoneal dialysis (PD) patients where the dynamics of serum potassium is more stable. Methods: Among 17,664 patients who started PD between January 1, 2007 and December 31, 2011 in a large US dialysis organization, we evaluated the association of serum potassium levels with all-cause and arrhythmia-related deaths across race/ethnicity using time-dependent Cox models with adjustments for demographics. We also used restricted cubic spline functions for serum potassium levels to explore non-linear associations. Results: Baseline serum potassium levels were the highest among Hispanics (4.2 ± 0.7 mEq/L) and lowest among non-Hispanic blacks (4.0 ± 0.7 mEq/L). Among 2,949 deaths during the follow-up of median 2.2 (interquartile ranges 1.3–3.2) years, 683 (23%) were arrhythmia-related deaths. Overall, both hyperkalemia and hypokalemia (i.e., serum potassium levels >5.0 and <3.5 mEq/L, respectively) were associated with higher all-cause and arrhythmia-related mortality. In a stratified analysis according to race/ethnicity, the association of hypokalemia with all-cause and arrhythmia-related mortality was consistent with an attenuation for arrhythmia-related mortality in non-Hispanic blacks. Hyperkalemia was associated with all-cause and arrhythmia-related mortality in non-Hispanic whites and non-Hispanic blacks, but no association was observed in Hispanics. Conclusion: Among incident PD patients, hypokalemia was consistently associated with all-cause and arrhythmia-related deaths irrespective of race/ethnicity. However, while hyperkalemia was associated with both death outcomes in non-Hispanic blacks and whites, it was not associated with either death outcome in Hispanic patients. Further studies are needed to demonstrate whether different strategies should be followed for the management of serum potassium levels according to race/ethnicity.

The relationship of plasma ADMA levels with cardiac functions and metabolic parameters in peritoneal dialysis patients

2012 ◽  
Vol 17 (3) ◽  
pp. 431-436
Author(s):  
Savas Ozturk ◽  
Serhat Karadag ◽  
Metin Yegen ◽  
Meltem Gursu ◽  
Sami Uzun ◽  
...  
Keyword(s):  
Peritoneal Dialysis ◽  
Metabolic Parameters ◽  
Dialysis Patients ◽  
Plasma Adma ◽  
Cardiac Functions ◽  
Relationship Of ◽  
The Relationship
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