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Free cysteine is increased in plasma from hemodialysis patients
Takeshi Nakanishi1, Yukiko Hasuike, Yoshinaga Otaki
1Department of Internal Medicine, Hyogo College of Medicine, Nishinomiya, Japan. t-nknd@hyo-med.ac.jp
Insights
Free cysteine levels in plasma are significantly higher in hemodialysis patients, suggesting its potential role in cardiovascular risk and atherosclerosis. This finding highlights the importance of measuring free thiols for better clinical predictions.
Area of Science:
- Biochemistry
- Nephrology
- Cardiovascular Medicine
Background:
- Total thiol concentration, encompassing bound and free forms, is typically measured in clinical studies.
- Free thiol forms may offer superior predictive value for cardiovascular risk compared to total thiols.
Purpose of the Study:
- To measure free homocysteine (Hcy) and cysteine (Cys) concentrations.
- To compare these levels in healthy controls and hemodialysis patients before and after dialysis.
Main Methods:
- Plasma samples from controls and hemodialysis patients were analyzed.
- Filtered and acid-soluble fractions were used to determine apparent concentrations of free Hcy and Cys.
Main Results:
- In controls, filtered cysteine was significantly lower than acid-soluble cysteine.
- Pre-hemodialysis patients exhibited over 60-fold higher filtered cysteine levels compared to controls.
- The free-to-total cysteine ratio was markedly elevated in pre-hemodialysis patients (40.9%) versus controls (1.6%).
Conclusions:
- The filtered thiol fraction can estimate solute transport during dialysis.
- Cysteine's role in atherosclerosis pathogenesis among hemodialysis patients warrants further investigation.
Background:
Although only the total thiol concentration, which includes bound and free forms, has been determined in most previous clinical studies, the free form may be a better predictor of cardiovascular risk.
Methods:
We measured the apparent concentration of free homocysteine (Hcy) and cysteine (Cys) in filtered and acid-soluble fractions of plasma in healthy control subjects and in patients with chronic renal failure just before and after a hemodialysis session.
Results:
In control, filtered Hcy and acid-soluble Hcy were similar, while filtered Cys was much smaller than in acid-soluble Cys. In prehemodialysis samples, filtered Cys was more than 60 times as abundant (259.2 +/- 26.2 micromol/L) as in control samples (4.1 +/- 0.7 micromol/L ). Free-to-total ratios for filtered Cys were 1.6 +/- 0.3% in controls, but 40.9 +/- 2.7% in prehemodialysis patients.
Conclusions:
The filtered fraction of thiols can be used to estimate solute transport across the dialysis membrane. In addition, the possible involvement of cysteine in the pathogenesis of atherosclerosis in hemodialysis patients should be reexamined.