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PubMed2006

Oxidative stress, advanced glycation end product, and coronary artery calcification in hemodialysis patients.

Coronary artery calcification is an index of the severity of atherosclerotic vascular disease, and may predict future adverse cardiovascular events in uremic patients undergoing hemodialysis (HD). HD patients are exposed to oxidative stress, and show high plasma levels of advanced glycation end products (AGEs). The association between oxidative stress, AGEs, established cardiovascular risk factors, and coronary artery calcification score (CACS) was studied in 225 HD patients (123 male, 102 female patients). CACS was measured by using multi-detector row computed tomography. Age, systolic blood pressure, calcium, calcium x phosphate, malondialdehyde, lipid peroxides, and pentosidine were significantly and positively correlated with CACS. Duration on HD tended to be positively correlated with CACS. From the independent variables included in the forward stepwise multiple linear regression analysis, only age, systolic blood pressure, lipid peroxides, calcium, and pentosidine were independently associated with CACS. The odds ratios for past history of coronary artery disease and the presence of diabetes mellitus for high CACS (> or =100) were 6.25 (95% confidence interval; 1.83-21.4) and 2.03 (95% confidence interval; 1.02-4.05), respectively. The plasma pentosidine was significantly and positively correlated with indoxyl sulfate. In conclusion, in addition to such traditional cardiovascular risk factors as past history, diabetes mellitus, aging, systolic blood pressure and calcium overload, oxidative stress (lipid peroxides), and AGE (pentosidine) are associated with extensive coronary artery calcification in HD patients. Lipid peroxidation and glycoxidation may be involved in the pathogenesis of coronary artery calcification.

Aged↗
PubMed2006

Indoxyl sulfate stimulates proliferation of rat vascular smooth muscle cells.

Vascular smooth muscle cell (VSMC) proliferation is a key event in the progression of arteriosclerosis. Clinical studies show that uremic toxins deteriorate the arteriosclerosis in renal failure patients. Indoxyl sulfate (IS) is a strong protein-bound uremic toxin, but the effect of IS on VSMC proliferation has not been studied. We examined the effect of IS on rat VSMC proliferation, assessed by a cell counting kit (4-[3-[4-lodophenyl]-2-4(4-nitrophenyl)-2H-5-tetrazolio-1,3-benzene disulfonate] assay) and by [(3)H]thymidine incorporation in vitro. We further evaluated a contribution of mitogen-activated protein kinase (MAPK; p44/42 MAPK) to VSMC proliferation by IS. Immunohistochemical staining was performed for VSMCs using antirat organic anion transporter (OAT)3 antibody. The mRNA expressions of platelet-derived growth factor (PDGF)-A and -C chains, and PDGF-beta receptor were evaluated by real-time PCR. IS stimulated the proliferation of VSMCs in a concentration-dependent manner and activated p44/42 MAPK. Concentration of IS needed to stimulate the proliferation of rat VSMC was about 250 microM, which is compatible with that in the serum of end-stage renal failure patients. PD98059 (10 microM), a selective inhibitor of MAPK/extracellular signal-regulated kinase, inhibited the IS-induced (250 microM) VSMC proliferation and phosphorylation of MAPK. Probenecid (0.5 mM), an inhibitor and substrate of OAT, inhibited the IS-induced (250 microM) VSMC proliferation. Rat OAT3 was detected in VSMCs. The mRNA expressions of PDGF-C chain and PDGF-beta receptor were significantly increased by IS. We conclude that IS directly stimulates rat VSMC proliferation and activates MAPK in vitro. This might be one of the mechanisms underlying the progression of atherosclerotic lesions in end-stage renal disease patients.

Animals↗
PubMed1998

Serum substances that interfere with thyroid hormone assays in patients with chronic renal failure.

OBJECTIVE: Serum thyroid hormone concentrations in patients with chronic renal failure are usually low, despite normal serum TSH levels. We investigated the effect on thyroid hormone assays of serum dialysable organic acids that are elevated in uraemic patients. PATIENTS: Serum samples from 42 patients with chronic renal failure who were receiving haemodialysis and 37 sex- and age-matched healthy subjects were examined. DESIGN AND MEASUREMENTS: Serum thyroid hormone concentrations were measured with an analogue radioimmunoassay (RIA), a labelled antibody assay, and an equilibrium dialysis/RIA method. Serum concentrations of organic acids were determined with high performance liquid chromatography. RESULTS: Serum thyroid hormone levels determined by an analogue RIA and a labelled antibody assay in uraemic patients increased, and serum concentrations of organic acids decreased following haemodialysis. A significant association existed between serum free T3 (FT3) levels determined by an analogue RIA and serum concentrations of indoxyl sulphate (IS) prior to dialysis. There was also a significant association between serum free T4 (FT4) levels determined by an analogue RIA and serum concentration of IS and hippuric acid (HA) prior to dialysis. There was a significant association between the changes of serum concentrations of indole acetic acid (IAA) and FT4 concentrations prior to and following haemodialysis when determined by an analogue RIA. Serum FT3 and FT4 levels significantly decreased after the addition of IS to serum from healthy subjects when determined by an analogue RIA but not by a labelled antibody assay. Serum FT4 levels, but not FT3 levels, decreased after addition of IAA when determined by an analogue RIA. Serum FT4 concentrations determined by an equilibrium dialysis/RIA were significantly higher than those determined by the other two methods. The addition of IS, IAA, and HA to serum samples from healthy subjects significantly increased FT4 concentrations when determined by an equilibrium dialysis/RIA method. CONCLUSIONS: Increased serum levels of indoxyl sulphate, indole acetic acid and hippuric acid in sera of uraemic patients may interfere with thyroid hormone measurements when an analogue radioimmunoassay is used. In contrast, there was little Interference with a labelled antibody assay. Dialysable organic acids may also interfere with thyroid hormone assays determined by an equilibrium dialysis/radioimmunoassay method.

Aged↗
PubMed2002

Role of blood-brain barrier organic anion transporter 3 (OAT3) in the efflux of indoxyl sulfate, a uremic toxin: its involvement in neurotransmitter metabolite clearance from the brain.

Renal impairment is associated with CNS dysfunctions and the accumulation of uremic toxins, such as indoxyl sulfate, in blood. To evaluate the relevance of indoxyl sulfate to CNS dysfunctions, we investigated the brain-to-blood transport of indoxyl sulfate at the blood-brain barrier (BBB) using the Brain Efflux Index method. [(3)H]Indoxyl sulfate undergoes efflux transport with an efflux transport rate of 1.08 x 10(-2)/min, and the process is saturable with a Km of 298 microm. This process is inhibited by para-aminohippuric acid, probenecid, benzylpenicillin, cimetidine and uremic toxinins, such as hippuric acid and 3-carboxy-4-methyl-5-propyl-2-furanpropanoic acid. RT-PCR revealed that an OAT3 mRNA is expressed in conditionally immortalized rat brain capillary endothelial cell lines and rat brain capillary fraction. Xenopus oocytes expressing OAT3 were found to exhibit [(3)H]indoxyl sulfate uptake, which was significantly inhibited by neurotransmitter metabolites, such as homovanillic acid and 3-methoxy-4-hydroxymandelic acid, and by acyclovir, cefazolin, baclofen, 6-mercaptopurine, benzoic acid, and ketoprofen. These results suggest that OAT3 mediates the brain-to-blood transport of indoxyl sulfate, and is also involved in the efflux transport of neurotransmitter metabolites and drugs. Therefore, inhibition of the brain-to-blood transport involving OAT3 would occur in uremia and lead to the accumulation of neurotransmitter metabolites and drugs in the brain.

Animals↗
PubMed2001

Protein-bound uremic solutes: the forgotten toxins.

The present concept of dialysis focuses mainly on the removal of small water-soluble compounds, and also, the currently applied kinetic parameters of dialysis adequacy are based on the behavior of water-soluble compounds. Nevertheless, many of the currently known biological effects in uremia are attributable to compounds with different physicochemical characteristics, and among these, protein-bound solutes play an important role. In this article, we review the characteristics and consequences of changes in protein binding in uremia, as well as the toxicity of the protein-bound uremic solutes 3-carboxy-4-methyl-5-propyl-2-furanpropionic acid (CMPF), indoxyl sulfate, hippuric acid, homocysteine, and p-cresol. Starting from the example of p-cresol, we then summarize the impact of protein-binding on dialytic removal, whereby it is concluded that this removal is largely hampered by this protein-binding compared with that of classic markers such as urea and creatinine. Alternative removal strategies, such as strategies to modify intestinal generation or absorption, are considered.

Animals↗
PubMed2002

Major role of organic anion transporter 3 in the transport of indoxyl sulfate in the kidney.

BACKGROUND: Indoxyl sulfate is a uremic toxin that accumulates in the body because of the patient's inability to excrete it and it induces a number of uremic symptoms and leads to chronic renal failure. The functional failure of the excretion system for indoxyl sulfate causes its accumulation in blood. The purpose of the present study was to characterize the transport mechanism responsible for the renal excretion of indoxyl sulfate. METHODS: The [3H]indoxyl sulfate transport mechanism was investigated using an in vivo tissue-sampling single-injection technique, the kidney uptake index (KUI) method. Rat organic anion transporter 3 (rOAT3)-expressing Xenopus laevis oocyte system was used for measuring [3H]indoxyl sulfate uptake activity. RESULTS: Probenecid showed a concentration-dependent inhibitory effect on the uptake of [3H]indoxyl sulfate using the KUI method, and uptake was inhibited by organic anions such as para-aminohippuric acid (PAH) and benzylpenicillin, by weak base such as cimetidine, and by uremic toxins, such as 3-carboxy-4-methyl-5-propyl-2-furanpropanoic acid (CMPF) and hippuric acid (HA). However, salicylic acid, indomethacin, 3,5,3'-triiodo-l-thyronine and indole acetic acid (IA) had no effect on the uptake. rOAT3-expressing oocytes exhibited uptake of [3H]indoxyl sulfate by rOAT3 (Km = 158 micromol/L). Moreover, a number of uremic toxins inhibited the uptake of [3H]indoxyl sulfate by rOAT3. CONCLUSIONS: These results suggest that rOAT3 is responsible for the renal uptake of indoxyl sulfate, and uremic toxins share the transport mechanism for indoxyl sulfate. Mutual inhibition of these uremic toxins via OAT3 may accelerate their accumulation in the body and, thereby, the progression of nephrotoxicity in uremia.

Animals↗
PubMed2003

Uremic toxins of organic anions up-regulate PAI-1 expression by induction of NF-kappaB and free radical in proximal tubular cells.

BACKGROUND: Uremic toxins have been suggested to promote progression of chronic renal failure. We have shown that organic anion transporter-mediated uptake of uremic toxins induces oxidative stress in opossum kidney renal tubular cells overexpressing the transporter. Plasminogen activator inhibitor-1 (PAI-1) and nuclear factor-kappa B (NF-kappaB) are major factors known to promote tubulointerstitial fibrosis. The present study examined the signaling pathway that is activated by uremic toxins to induce PAI-1 and activate NF-kappaB in human renal proximal tubular cells (HK-2). METHODS: Uremic toxins in the form of organic anion were examined their ability to induce oxidative stress, PAI-1 gene expression, and NF-kappaB activation in HK-2. PAI-1 expression was measured by enzyme-linked immunosorbent assay (ELISA) and the Northern blotting. Human PAI-1 promoter activity was estimated by luciferase reporter gene (NKkappaB-luc) assay. NF-kappaB activation was measured by the pNFkappaB-luc reporter gene and electrophretic gel mobility shift assay. RESULTS: Among organic anion species tested, indoxyl sulfate and indoleacetic acid induced free radical production in HK-2. A nonspecific transporter inhibitor (probenecid) suppressed the IS-stimulated radical production. Indoxyl sulfate and indoleacetic acid dose dependently increased the expressions of PAI-1 mRNA and protein in these cells. The luciferase reporter gene assay revealed that indoxyl sulfate and indoleacetic acid dose dependently activated NF-kappaB and PAI-1 promoter. Activation of NF-kappaB was also confirmed by an electrophoretic gel mobility shift assay. Both antioxidant and NF-kappaB inhibitors dose dependently inhibited the activation of PAI-1 promoter by indoxyl sulfate. CONCLUSION: Uremic toxins induce free radical production by renal tubular cells and activate NF-kappaB which, in turn, up-regulates PAI-1 expression. Thus, progression of chronic renal failure may be promoted by PAI-1 up-regulation induced by uremic toxins.

Anions↗
PubMed2001

An oral adsorbent ameliorates renal overload of indoxyl sulfate and progression of renal failure in diabetic rats.

Otsuka Long-Evans Tokushima Fatty (OLETF) rats were established as a new model of non-insulin-dependent diabetes mellitus. An oral adsorbent, AST-120, is effective in removing such uremic toxins as indoxyl sulfate and delays the progression of chronic renal failure (CRF). This study was designed to determine the effects of AST-120 on the progression of CRF in uninephrectomized OLETF (1/2NxOLETF) rats and the localization of indoxyl sulfate in their kidneys. Four weeks after unilateral nephrectomy, 14 OLETF rats were divided into two groups; AST-120-administered and control 1/2NxOLETF rats. Long-Evans Tokushima Otsuka rats, which are genetically similar to the OLETF rats but not diabetic, were also included. After the administration of AST-120 for 36 weeks, we examined the effects of AST-120 on renal functional and pathological changes in the three groups. The control 1/2NxOLETF rats showed marked hyperglycemia, hyperlipidemia, renal failure, glomerular sclerosis, and tubulointerstitial injury. The administration of AST-120 to the 1/2NxOLETF rats retarded the progression of renal dysfunction and fibrosis, as well as hyperlipidemia, and reduced serum and urinary levels of indoxyl sulfate. Immunohistochemistry showed that AST-120 markedly reduced the overload of indoxyl sulfate in tubular epithelial cells, especially dilated tubules, of the 1/2NxOLETF rats. In conclusion, AST-120 delayed the progression of renal failure and fibrosis in 1/2NxOLETF rats and decreased the overload of indoxyl sulfate on renal tubular cells.

Administration, Oral↗
PubMed2002

Behavior of non-protein-bound and protein-bound uremic solutes during daily hemodialysis.

BACKGROUND: In the last few years, renewed interest in daily short hemodialysis (DHD; six 2-hour sessions per week) has become apparent as a consequence of the better clinical outcome of patients treated by this schedule. Uremic syndrome is characterized by the retention of a large number of toxins with different molecular masses and chemical properties. Some toxins are water soluble and non-protein bound, whereas others are partially lipophilic and protein bound. There is increased evidence that protein-bound toxins are responsible for the biochemical and functional alterations present in uremic syndrome, and the kinetics of urea is not applicable to these substances for their removal. The aim of this study is to investigate whether DHD is accompanied by increased removal of non-protein-bound and protein-bound toxins and a decrease in their prehemodialysis (pre-HD) serum levels. PATIENTS AND METHODS: We studied 14 patients with end-stage renal disease treated by standard HD (SHD; three 4-hour sessions per week) for at least 6 months and randomly assigned them to a two-period crossover study (SHD to DHD and DHD to SHD). Patients maintained the same dialyzer, dialysate, and Kt/V during the entire study. At the end of 6 months of SHD and 6 months of DHD, we evaluated hemoglobin levels, hematocrits, recombinant human erythropoietin doses, and pre-HD and post-HD concentrations of serum urea, creatinine, uric acid, and the following protein-bound toxins: 3-carboxy-4-methyl-5-propyl-2-furanpropionic acid, p-cresol, indole-3-acetic acid, indoxyl sulfate, and hippuric acid. RESULTS: Values for hemoglobin, hematocrit, and recombinant human erythropoietin dose did not change during the two study periods. Pre-HD concentrations of creatinine, urea, and uric acid decreased on DHD (creatinine, from 8.7 +/- 1.9 to 7.8 +/- 1.6 mg/dL; P < 0.05; urea, from 149.4 +/- 28.8 to 132.7 +/- 40 mg/dL; P = 0.05; uric acid, from 9.14 +/- 1.49 to 8.16 +/- 1.98 mg/dL; P = 0.06). Concerning protein-bound toxins, lower pre-HD levels during DHD were reported for indole-3-acetic acid (SHD, 0.16 +/- 0.04 mg/dL; DHD, 0.13 +/- 0.03 mg/dL; P = 0.01), indoxyl sulfate (SHD, 3.35 +/- 1.68 mg/dL; DHD, 2.85 +/- 1.08 mg/dL; P = 0.02), and p-cresol at the borderline of significance (SHD, 0.96 +/- 0.59 mg/dL; DHD, 0.78 +/- 0.33 mg/dL; P = 0.07). CONCLUSION: Such non-protein-bound compounds as uric acid, creatinine, and urea were removed significantly better by DHD, and pre-HD serum levels were reduced. Furthermore, pre-HD concentrations of some protein-bound solutes, such as indole-3-acetic acid, indoxyl sulfate, and p-cresol, also were lower during DHD.

Creatinine↗
PubMed2003

Effects of the oral adsorbent AST-120 on tryptophan metabolism in uremic patients.

BACKGROUND: Tryptophan (TRP), an essential amino acid, is bound mostly to albumin in plasma. However, it is reported that binding is inhibited by indoles that accumulate in uremic plasma. This may be responsible for the malnutrition observed in uremic patients. AST-120, an oral adsorbent of uremic toxins, can reduce concentrations of indoxyl sulfate (IS), the most abundant indolic metabolite in uremic plasma. We therefore investigated whether AST-120 recovers TRP binding to plasma proteins and improves the nutritional state of uremic patients. METHODS: The in vitro binding ratio of TRP to bovine serum albumin (BSA) was measured in the presence of IS by the equilibrium dialysis technique. In addition, five predialysis patients with chronic renal failure (CRF) were administered AST-120 for 2 months. Plasma concentrations of total TRP, IS, and free TRP were measured in five healthy volunteers (normal [N] group) and five patients with CRF before and after 2 weeks of AST-120 therapy (6 g/d). Their nutritional statuses also were compared before and after 2 months of AST-120 administration. RESULTS: IS inhibited in vitro binding of TRP to BSA in a dose-dependent manner. Total TRP concentrations and protein-binding ratios in patients with CRF (0.90 +/- 0.08 mg/dL and 68.7% +/- 6.8%, respectively) were significantly lower than those in the N group (2.45 +/- 0.45 mg/dL and 92.0% +/- 1.4%, respectively). However, a 2-week administration of AST-120 significantly reduced IS levels from 1.79 +/- 1.01 to 1.15 +/- 0.85 mg/dL (N group, 0.06 +/- 0.01 mg/dL), increased total TRP levels (1.16 +/- 0.18 mg/dL), and improved the TRP plasma protein-binding ratio to 83.1% +/- 3.8%, whereas total protein and albumin levels remained unchanged. After 2 months of AST-120 administration, serum albumin and transferrin levels increased significantly. CONCLUSION: AST-120 improves nutritional state, at least partly through correcting impaired TRP metabolism, in patients with CRF.

Administration, Oral↗
PubMed2003

Bifidobacterium in gastro-resistant seamless capsule reduces serum levels of indoxyl sulfate in patients on hemodialysis.

BACKGROUND: Intestinal microflora is deranged in hemodialysis (HD) patients as increased aerobacteria such as Escherichia coli, and decreased anaerobacteria such as bifidobacteria. Indole, a precursor of indoxyl sulfate, is produced by E coli but not by bifidobacteria. The serum levels of indoxyl sulfate are increased markedly in HD patients and cannot be reduced efficiently by HD because of its albumin binding. METHODS: To compare the effect of oral administration of Bifidobacterium longum in gastro-resistant seamless capsule (Bifina) on indoxyl sulfate levels with that of Bifidobacteria in powder formulation (Lac B), Bifina was administered to 11 HD patients for 5 weeks, and Lac B to another group of 11 HD patients for 5 weeks. The authors measured the serum level of indoxyl sulfate by using high-performance liquid chromatography. RESULTS: The pre-HD serum levels of indoxyl sulfate significantly decreased in Bifina-treated patients (before, 4.9 +/- 1.7 mg/dL, 4.5 mg/dL, mean +/- SD, median, after 5 weeks, 3.5 +/- 1.3 mg/dL, 3.8 mg/dL; P < 0.005). However, they did not decrease in the Lac B-treated patients (before, 4.8 +/- 1.4 mg/dL, 4.5 mg/dL, after 5 weeks, 5.2 +/- 2.0 mg/dL, 5.1 mg/dL). CONCLUSION: Oral administration of Bifina to HD patients is effective in reducing the serum levels of indoxyl sulfate by correcting the intestinal microflora. Gastro-resistant seamless capsule prevents bifidobacteria from its inactivation in acidic gastric juice, and allows it to be actived in the intestine.

Administration, Oral↗
PubMed2003

Protein-bound uremic retention solutes.

Protein-bound uremic retention solutes are molecules with low molecular weight (MW) but should be considered middle or high MW substances. This article describes the best known substances of this group, which include p-cresol, indoxyl sulfate, hippuric acid, 3-carboxy-4-methyl-5-propyl-2-furan-propionic acid (CMPF), and homocysteine. At concentrations encountered during uremia, p-cresol inhibits phagocyte function and decreases leukocyte adhesion to cytokine-stimulated endothelial cells. CMPF has been implicated in anemia and neurologic abnormalities of uremia. CMPF could alter the metabolism of drugs of inhibiting their binding to albumin and their tubular excretion. Indoxyl sulfate administrated to uremic rats increases the rate of progression of renal failure. Hippuric acid inhibits glucose utilization in the muscle, and its serum concentration is correlated with neurologic symptoms of uremia. Homocysteine predisposes uremic patients to cardiovascular disease through impairment of endothelial and smooth muscle cell functions. The removal of protein-bound compounds by conventional hemodialysis is low. Other strategies to decrease their concentrations include increase in dialyze pore size, daily hemodialysis, peritoneal dialysis, reduction of production or acceleration of degradation, and preservation of residual renal function.

Animals↗
PubMed2005

Beneficial effects of Bifidobacteria in a gastroresistant seamless capsule on hyperhomocysteinemia in hemodialysis patients.

Intestinal microflora is deranged in hemodialysis (HD) patients as an increase in aerobic bacteria such as Escherichia coli and a decrease in anaerobic bacteria such as Bifidobacterium . Bifidobacteria ferment carbohydrates to produce acetic acid and lactic acid, which inhibit the intestinal putrefaction. Thus, intake of Bifidobacteria effectively restores the disturbed microflora to normal. However, Bifidobacteria in most medical products and healthy foods cannot usually survive because of exposure to gastric juices before it reaches the intestines. A gastroresistant seamless capsule prevents Bifidobacteria from inactivation by acidic gastric juice and allows it to be active in the intestines. We showed that the oral administration of Bifidobacterium longum in a gastroresistant seamless capsule to HD patients is effective in decreasing the pre-HD serum levels of homocysteine, indoxyl sulfate, and triglyceride. The reduction in the serum level of homocysteine is mainly attributable to the supply of folate produced by Bifidobacterium longum in the human intestines.

Bifidobacterium↗
PubMed2006

Accumulation of indoxyl sulfate in OAT1/3-positive tubular cells in kidneys of patients with chronic renal failure.

Indoxyl sulfate shows nephrotoxicity and is a stimulating factor for progression of chronic renal failure (CRF). Indoxyl sulfate is taken up by renal proximal tubular cells through organic anion transporters 1 and 3 (OAT1/3), and is accumulated in the renal proximal tubular cells of uremic rats. To determine whether indoxyl sulfate is accumulated in human OAT1/3 (hOAT1/3)-positive renal proximal tubular cells, localization of indoxyl sulfate and hOAT1/3 in the kidneys of CRF patients was determined by immunohistochemistry. Kidney samples were obtained by autopsy from 9 CRF patients (mean serum creatinine 4.7 mg/dL, ranging from 2.0 to 14.5 mg/dL) and 9 patients with non-kidney disease (mean serum creatinine 0.6 mg/dL, ranging from 0.4 to 0.9 mg/dL). Immunohistochemistry was performed using antibodies against indoxyl sulfate, hOAT1, and hOAT3. Indoxyl sulfate was localized in the hOAT1- and hOAT3-positive renal tubular cells in the kidneys of CRF patients. The indoxyl sulfate-positive area in the kidneys was markedly increased in the kidneys of CRF patients compared with patients with non-kidney disease. The indoxyl sulfate-positive area was positively correlated with serum creatinine. In conclusion, in CRF patients, indoxyl sulfate is accumulated in the tubular cells with hOAT1 and/or hOAT3 localized at the basolateral membrane. The extent of indoxyl sulfate accumulation in the kidneys is more prominent in those patients with more severe CRF.

Aged↗
PubMed2007

Indoxyl sulfate-lowering capacity of oral sorbents affects the prognosis of kidney function and oxidative stress in chronic kidney disease.

OBJECTIVES: Indoxyl sulfate shows nephrotoxicity and is a stimulating factor for progression of chronic kidney disease (CKD). This study was conducted to determine (1) whether the indoxyl sulfate-lowering capacity of oral sorbents (Kremezin [AST-120], Kureha Corporation, Tokyo, Japan; Merckmezin, Merck Hoei Ltd., Osaka, Japan) affects the prognosis of kidney function in CKD, and (2) whether oral sorbents reduce the markers of oxidative stress. METHODS: Rats with CKD were produced by 4/5 nephrectomy and were randomized into 3 groups: control rats, Merckmezin-treated rats, and Kremezin-treated rats. Kremezin and Merckmezin were administered to rats at a dose of 4 g/kg with powder chow for 16 weeks, whereas powder chow alone was administered to control rats. RESULTS: Administration of Kremezin significantly decreased serum and urine levels of indoxyl sulfate and serum creatinine and significantly increased creatinine clearance as compared with control values. The change in serum indoxyl sulfate noted from the initial to the final week showed a positive correlation with the change in serum creatinine and a negative correlation with the change in creatinine clearance. Kremezin significantly reduced urine levels of acrolein, a marker of oxidative stress, as compared with control levels. CONCLUSIONS: The indoxyl sulfate-lowering capacity of oral adsorbents affects the prognosis of kidney function in CKD. The more serum indoxyl sulfate is reduced, the better kidney function is preserved. Kremezin alleviates oxidative stress in the kidneys by reducing serum levels of indoxyl sulfate.

Acrolein↗
PubMed1979

Diarrhea after gastrectomy and vagotomy.

Development of diarrhea in a patient following gastric surgery can be a confusing problem. The clinician is forced to consider and exclude causes that may be independent of the surgery as well as those that are unique to the postgastrectomy state. An orderly approach is mandatory for appropriate workup and management.

Biopsy↗
PubMed2006

Hormonal replacement therapy in an animal model with chronic renal failure and gonadectomy: biochemical and hematological study.

The aim of the present study was to investigate the effects of subcutaneous administration of estradiol propionate (450 microg/kg female rat/day) or testosterone propionate (2 mg/kg male rat/day) for 4 weeks on some biochemical and hematological variables in intact and gonadectomized male and female rats with chronic renal failure (CRF) induced by 7/8 nephrectomy (remnant kidney model). Twenty-four hours after the last injection, rats were decapitated and blood samples were collected for complete hemogram and for measuring the concentrations of creatinine, urea, and indoxyl sulphate in plasma. Body weights of all rats were taken every week during the experimental period. The hematological and biochemical parameters measured in the sham-operated and gonadectomized rats were not significantly different from those in intact rats. Induction of CRF significantly increased the concentrations of creatinine, urea, and indoxyl sulphate by about 90-300% (P < 0.05), and caused signs indicative of anemia. These effects were significantly exacerbated in gonadectomized rats with CRF, and were partially and significantly reversed by exogenous administration of testosterone/estradiol. The changes induced by CRF and gonadectomy on the hematocrit (HTC) and hemoglobin concentration (HGB) were more pronounced in females than in males. The HTC and HGB in gonadectomized male rats with CRF were not significantly different from the controls. In the rest of the groups, there were no significant gender effects in the measured variables. It is suggested that, in the used rat model of CRF, there is depressed growth; significant increases in the plasma concentrations of creatinine, urea, and indoxyl sulphate; and anemia. All these signs were significantly and partially reversed by estradiol and testosterone therapy equally in female and male rats, respectively.

Animals↗