The Therapeutic Strategies for Uremic Toxins Control in Chronic Kidney Disease.

Uremic toxins (UTs) are mainly produced by protein metabolized by the intestinal microbiota and converted in the liver or by mitochondria or other enzymes. The accumulation of UTs can damage the intestinal barrier integrity and cause vascular damage and progressive kidney damage. Together, these factors lead to metabolic imbalances, which in turn increase oxidative stress and inflammation and then produce uremia that affects many organs and causes diseases including renal fibrosis, vascular disease, and renal osteodystrophy. This article is based on the theory of the intestinal-renal axis, from bench to bedside, and it discusses nonextracorporeal therapies for UTs, which are classified into three categories: medication, diet and supplement therapy, and complementary and alternative medicine (CAM) and other therapies. The effects of medications such as AST-120 and meclofenamate are described. Diet and supplement therapies include plant-based diet, very low-protein diet, probiotics, prebiotics, synbiotics, and nutraceuticals. The research status of Chinese herbal medicine is discussed for CAM and other therapies. This review can provide some treatment recommendations for the reduction of UTs in patients with chronic kidney disease.

Concerted outcome of metformin and low dose of radiation in modulation of cisplatin induced uremic encephalopathy via renal and neural preservation.

AIM: The therapeutic expediency of cisplatin was limited due to its nephrotoxic side effects, so this study planned to assess the nephrotic and neuroprotective impact of metformin (MET) and low-dose radiation (LDR) in cisplatin-prompted kidney injury and uremic encephalopathy (UE). METHODS: The effect of the 10-day MET treatment (200 mg/kg, orally) and/or fractionated LDR (0.25 Gy, of the total dose of 0.5 Gy, 1st and 7th day, respectively) on (5 mg/kg, intraperitoneally) cisplatin as a single dose was administered at the 5th day. Serum urea, creatinine and renal kidney injury molecule-1 were measured for the assessment of kidney function. Furthermore, the antioxidant potential in the renal and brain tissues was evaluated through, malondialdehyde and reduced glutathione estimation. Moreover, renal apoptotic markers: AMP-activated protein kinase, lipocalin, B-cell lymphoma 2 associated X protein, B-cell lymphoma 2, P53 and beclin 1 were estimated. UE was evaluated through the determination of serum inflammatory markers: nuclear factor kappa B, tumor-necrosis factor-α and interleukin 1 beta likewise, the cognitive deficits were assessed via forced swimming test, gamma-aminobutyric acid, n-methyl-d-aspartate and neuronal nitric oxide synthases besides AMP-activated protein kinase, light chain 3 and caspase3 levels in rats' cerebella. KEY FINDINGS: The obtained results revealed a noticeable improvement in the previously mentioned biochemical factors and behavioral tasks that was reinforced by histopathological examination when using the present remedy. SIGNIFICANCE: metformin and low doses of radiation afforded renoprotection and neuroprotection against cisplatin-induced acute uremic encephalopathy.

The Links between Microbiome and Uremic Toxins in Acute Kidney Injury: Beyond Gut Feeling-A Systematic Review.

The last years have brought an abundance of data on the existence of a gut-kidney axis and the importance of microbiome in kidney injury. Data on kidney-gut crosstalk suggest the possibility that microbiota alter renal inflammation; we therefore aimed to answer questions about the role of microbiome and gut-derived toxins in acute kidney injury. PubMed and Cochrane Library were searched from inception to October 10, 2020 for relevant studies with an additional search performed on ClinicalTrials.gov. We identified 33 eligible articles and one ongoing trial (21 original studies and 12 reviews/commentaries), which were included in this systematic review. Experimental studies prove the existence of a kidney-gut axis, focusing on the role of gut-derived uremic toxins and providing concepts that modification of the microbiota composition may result in better AKI outcomes. Small interventional studies in animal models and in humans show promising results, therefore, microbiome-targeted therapy for AKI treatment might be a promising possibility.

p-Cresol Sulfate Caused Behavior Disorders and Neurodegeneration in Mice with Unilateral Nephrectomy Involving Oxidative Stress and Neuroinflammation.

Protein-bound uremic toxins, such as p-cresol sulfate (PCS), can be accumulated with declined renal function and aging and is closely linked with central nervous system (CNS) diseases. In the periphery, PCS has effects on oxidative stress and inflammation. Since oxidative stress and inflammation have substantial roles in the pathogenesis of neurological disorders, the CNS effects of PCS were investigated in unilateral nephrectomized C57/BL/6 mice. Unlike intact mice, unilateral nephrectomized mice showed increased circulating levels of PCS after exogenous administration. Upon PCS exposure, the unilateral nephrectomized mice developed depression-like, anxiety-like, and cognitive impairment behaviors with brain PCS accumulation in comparison with the nephrectomy-only group. In the prefrontal cortical tissues, neuronal cell survival and neurogenesis were impaired along with increased apoptosis, oxidative stress, and neuroinflammation. Circulating brain-derived neurotrophic factors (BDNF) and serotonin were decreased in association with increased corticosterone and repressor element-1 silencing transcription factor (REST), regulators involved in neurological disorders. On the contrary, these PCS-induced changes were alleviated by uremic toxin absorbent AST-120. Taken together, PCS administration in mice with nephrectomy contributed to neurological disorders with increased oxidative stress and neuroinflammation, which were alleviated by PCS chelation. It is suggested that PCS may be a therapeutic target for chronic kidney disease-associated CNS diseases.

Neurobehavioral effects of uremic toxin-indoxyl sulfate in the rat model.

Chronic kidney disease (CKD) is deemed to be a worldwide health concern connected with neurological manifestations. The etiology of central nervous system (CNS) disorders in CKD is still not fully understood, however particular attention is currently being paid to the impact of accumulated toxins. Indoxyl sulfate (IS) is one of the most potent uremic toxins. The purpose of the present study was to assess IS concentrations in the cerebellum, brainstem, cortex, hypothalamus, and striatum with hippocampus of rats chronically exposed to IS. To evaluate IS impact on neurochemical and behavioral alterations, we examined its influence on brain levels of norepinephrine, epinephrine, dopamine, serotonin and their metabolites, as well as changes in behavioral tests (open field test, elevated plus maze test, chimney test, T maze test, and splash test). Our results show the highest IS accumulation in the brainstem. IS leads to behavioral alterations involving apathetic behavior, increased stress sensitivity, and reduced locomotor and exploratory activity. Besides, IS contributes to the impairment of spatial memory and motor coordination. Furthermore, we observed reduced levels of norepinephrine, dopamine or serotonin, mainly in the brainstem. Our findings indicate that IS can be one of the crucial uremic factors responsible for altered mental status in CKD.

Therapeutic Targeting of Aristolochic Acid Induced Uremic Toxin Retention, SMAD 2/3 and JNK/ERK Pathways in Tubulointerstitial Fibrosis: Nephroprotective Role of Propolis in Chronic Kidney Disease.

The nephrotoxicity of aristolochic acids (AAs), p-cresyl sulfate (PCS) and indoxyl sulfate (IS) were well-documented, culminating in tubulointerstitial fibrosis (TIF), advanced chronic kidney disease (CKD) and fatal urothelial cancer. Nonetheless, information regarding the attenuation of AAs-induced nephropathy (AAN) and uremic toxin retention is scarce. Propolis is a versatile natural product, exerting anti-oxidant, anti-cancer and anti-fibrotic properties. We aimed to evaluate nephroprotective effects of propolis extract (PE) in a murine model. AAN was developed to retain circulating PCS and IS using C57BL/6 mice, mimicking human CKD. The kidney sizes/masses, renal function indicators, plasma concentrations of PCS/IS, tissue expressions of TIF, α-SMA, collagen IaI, collagen IV and signaling pathways in transforming growth factor-ß (TGF-ß) family were analyzed among the control, PE, AAN, and AAN-PE groups. PE ameliorated AAN-induced renal atrophy, renal function deterioration, TIF, plasma retention of PCS and IS. PE also suppressed α-SMA expression and deposition of collagen IaI and IV in the fibrotic epithelial-mesenchymal transition. Notably, PE treatment in AAN model inhibited not only SMAD 2/3-dependent pathways but also SMAD-independent JNK/ERK activation in the signaling cascades of TGF-ß family. Through disrupting fibrotic epithelial-mesenchymal transition and TGF-ß signaling transduction pathways, PE improves TIF and thereby facilitates renal excretion of PCS and IS in AAN. In light of multi-faced toxicity of AAs, PE may be capable of developing a new potential drug to treat CKD patients exposed to AAs.

Digital radiography as an alternative method in the evaluation of bone density in uremic rats / Radiografia digital como método alternativo na avaliação da densidade óssea em ratos urêmicos

ABSTRACT Introduction: Digital radiography (DRx) may provide a suitable alternative to investigate mineral and bone disorder (MBD) and loss of bone density (BD) in rodent models of chronic kidney disease (CKD). The objective of this study was to use DRx to evaluate BD in CKD rats, and to evaluate the correlation between DRx findings and serum MBD markers and bone histomorphometry. Methods: Uremia was induced by feeding Wistar rats an adenine-enriched diet (0.75% for 4 weeks/0.10% for 3 weeks); outcomes were compared to a control group at experimental weeks 3, 4, and 7. The following biochemical markers were measured: creatinine clearance (CrC), phosphate (P), calcium (Ca), fractional excretion of P (FeP), alkaline phosphatase (ALP), fibroblast growth factor-23 (FGF-23), and parathyroid hormone (PTH). DRx imaging was performed and histomorphometry analysis was conducted using the left femur. Results: As expected, at week 7, uremic rats presented with reduced CrC and higher levels of P, FeP, and ALP compared to controls. DRx confirmed the lower BD in uremic animals (0.57±0.07 vs. 0.68 ± 0.06 a.u.; p = 0.016) compared to controls at the end of week 7, when MBD was more prominent. A severe form of high-turnover bone disease accompanied these biochemical changes. BD measured on DRx correlated to P (r=-0.81; p = 0.002), ALP (r = -0.69, p = 0.01), PTH (r = -0.83, p = 0.01), OS/BS (r = -0.70; p = 0.02), and ObS/BS (r = -0.70; p = 0.02). Conclusion: BD quantified by DRx was associated with the typical complications of MBD in CKD and showed to be viable in the evaluation of bone alterations in CKD.

RESUMO Introdução: A radiografia digital (RxD) pode representar uma alternativa adequada para investigar o distúrbio mineral e ósseo (DMO) e a perda de densidade óssea (DO) em modelos de roedores da doença renal crônica (DRC). O objetivo deste estudo foi utilizar a RxD para avaliar a DO em ratos com DRC, e avaliar a correlação entre os achados da RxD e marcadores séricos de DMO e histomorfometria óssea. Métodos: A uremia foi induzida pela alimentação de ratos Wistar com dieta enriquecida com adenina (0,75% por 4 semanas/0,10% por 3 semanas); os resultados foram comparados com um grupo controle nas semanas experimentais 3, 4 e 7. Os seguintes marcadores bioquímicos foram medidos: clearance de creatinina (CCr), fosfato (P), cálcio (Ca), fração excretada de P (FeP), fosfatase alcalina (ALP), fator de crescimento de fibroblastos-23 (FGF-23) e paratormônio (PTH). A imagem da RxD foi obtida e a análise histomorfométrica foi realizada com o fêmur esquerdo. Resultados: como esperado, na semana 7, os ratos urêmicos apresentaram redução do CCr e níveis mais altos de P, FeP e ALP em comparação aos controles. A RxD confirmou a menor DO em animais urêmicos (0,57 ± 0,07 vs. 0,68 ± 0,06 u.a.; p = 0,016) em comparação aos controles no final da semana 7, quando a DMO foi mais proeminente. Uma forma grave de doença óssea de alta renovação celular acompanhou essas mudanças bioquímicas. A DO, medida na RxD foi correlacionada a P (r = -0,81; p = 0,002), ALP (r = -0,69, p = 0,01), PTH (r = -0,83, p = 0,01), OS/BS (r = -0,70 p = 0,02) e Ob.S/BS (r = -0,70; p = 0,02). Conclusão: A DO quantificada por RxD esteve associada às complicações típicas da DMO na DRC e mostrou-se viável na avaliação de alterações ósseas na DRC.

Indoxyl Sulfate Contributes to Uremic Sarcopenia by Inducing Apoptosis in Myoblasts.

OBJETIVE: Uremic sarcopenia is a complication of chronic kidney disease, particularly in its later stages, which leads to musculoskeletal disability. Uremic toxins have been linked to the pathogenesis of several manifestations of uremic syndrome. We sought to investigate whether indoxyl sulphate (IS), a protein-bound uremic toxin, is implicated in the development of uremic sarcopenia. MATERIAL AND METHODS: Myoblasts were exposed to IS at normal (0.6 mg/L, IS0.6), uremic (53 mg/L, IS53) or maximum uremic (236 mg/L, IS236) concentrations for 24, 48 and 72 h. Cell viability was evaluated by MTT assay and by 7-aminoactinomycin D staining. ROS generation and apoptosis were evaluated by flow cytometry. MyoD and myogenin mRNA expression was evaluated by qRT-PCR and myosin heavy chain expression by immunocytochemistry. RESULTS: Myoblast viability was reduced by IS236 in a time-dependent pattern (p <0.05; 84.4, 68.0, and 63.6%). ROS production was significantly higher (p <0.05) in cells exposed to IS53 and IS236 compared to control (untreated cells). The apoptosis rate was significantly higher in cells treated with IS53 and IS236 than in control after 48h (p <0.05; 4.7 ± 0.1% and 4.6 ± 0.3% vs. 3.1 ± 0.1%, respectively) and 72h (p <0.05; 9.6 ± 1.1% and 10.4 ± 0.3% vs. 3.1 ± 0.7%, respectively). No effect was observed on MyoD, myogenin, myosin heavy chain expression, and markers of myoblast differentiation at any IS concentration tested or time-point experiment. CONCLUSIONS: These data indicate that IS has direct toxic effects on myoblast by decreasing its viability and increasing cell apoptosis. IS may be a potential target for treating uremic sarcopenia.

Digital radiography as an alternative method in the evaluation of bone density in uremic rats.

INTRODUCTION: Digital radiography (DRx) may provide a suitable alternative to investigate mineral and bone disorder (MBD) and loss of bone density (BD) in rodent models of chronic kidney disease (CKD). The objective of this study was to use DRx to evaluate BD in CKD rats, and to evaluate the correlation between DRx findings and serum MBD markers and bone histomorphometry. METHODS: Uremia was induced by feeding Wistar rats an adenine-enriched diet (0.75% for 4 weeks/0.10% for 3 weeks); outcomes were compared to a control group at experimental weeks 3, 4, and 7. The following biochemical markers were measured: creatinine clearance (CrC), phosphate (P), calcium (Ca), fractional excretion of P (FeP), alkaline phosphatase (ALP), fibroblast growth factor-23 (FGF-23), and parathyroid hormone (PTH). DRx imaging was performed and histomorphometry analysis was conducted using the left femur. RESULTS: As expected, at week 7, uremic rats presented with reduced CrC and higher levels of P, FeP, and ALP compared to controls. DRx confirmed the lower BD in uremic animals (0.57±0.07 vs. 0.68 ± 0.06 a.u.; p = 0.016) compared to controls at the end of week 7, when MBD was more prominent. A severe form of high-turnover bone disease accompanied these biochemical changes. BD measured on DRx correlated to P (r=-0.81; p = 0.002), ALP (r = -0.69, p = 0.01), PTH (r = -0.83, p = 0.01), OS/BS (r = -0.70; p = 0.02), and ObS/BS (r = -0.70; p = 0.02). CONCLUSION: BD quantified by DRx was associated with the typical complications of MBD in CKD and showed to be viable in the evaluation of bone alterations in CKD.

Therapeutic Prospective of a Spore-Forming Probiotic-Bacillus clausii UBBC07 Against Acetaminophen-Induced Uremia in Rats.

To screen Bacillus clausii UBBC07 as a putative probiotic strain and to examine the protective effect of probiotic-B. clausii UBBC07 spore on uremia on rats induced by acetaminophen. In vitro tests performed to screen potential probiotic strains were gastric and bile acid resistance and ability to reduce pathogen adhesion to surfaces. An in vivo study was performed on rats (n = 18) which were randomly divided into three groups: group I, control-receives normal food and water, groups II and III receive acetaminophen i.p. at the dose of 550 mg/kg/day for 10 days, groups III was treated with B. clausii UBBC07 at a dose of 1 × 109 CFU/day for 15 days. Urea, creatinine, malondialdehyde (MDA), and GSH levels and antioxidant enzymes like super oxide dismutase (SOD) and catalase activity were considered to analyze renal failure. Plasma urea and creatinine levels (p < 0.05) significantly increase and SOD, catalase, and GSH activity level significantly decrease in group II as compared with the control group. After treatment with probiotic, there was a significant increase in SOD and catalase (p < 0.05) and a significant decrease in serum urea, creatinine, and MDA (p < 0.05) in group III in response to group II. The results also revealed that probiotic was able to tolerate pH 3.0-9.0 and 0.3% bile salt. The present study suggests that B. clausii UBBC07 could be used as a novel alternative natural therapy for uremia, a major syndrome of CKD.

Vitamin D-regulated osteocytic sclerostin and BMP2 modulate uremic extraskeletal calcification.

We induced chronic kidney disease (CKD) with adenine in WT mice, mice with osteocyte-specific deletion of Cyp27b1, encoding the 25-hydroxyvitamin D 1(OH)ase [Oct-1(OH)ase-/-], and mice with global deletion of Cyp27b1 [global-1α(OH)ase-/-]; we then compared extraskeletal calcification. After adenine treatment, mice displayed increased blood urea nitrogen, decreased serum 1,25(OH)2D, and severe hyperparathyroidism. Skeletal expression of Cyp27b1 and of sclerostin and serum sclerostin all increased in WT mice but not in Oct-1α(OH)ase-/- mice or global-1α(OH)ase-/- mice. In contrast, skeletal expression of BMP2 and serum BMP2 rose in the Oct-1α(OH)ase-/- mice and in the global-1α(OH)ase-/- mice. Extraskeletal calcification occurred in muscle and blood vessels of mice with CKD and was highest in Oct-1α(OH)ase-/-mice. In vitro, recombinant sclerostin (100 ng/mL) significantly suppressed BMP2-induced osteoblastic transdifferentiation of vascular smooth muscle A7r5 cells and diminished BMP2-induced mineralization. Our study provides evidence that local osteocytic production of 1,25(OH)2D stimulates sclerostin and inhibits BMP2 production in murine CKD, thus mitigating osteoblastic transdifferentiation and mineralization of soft tissues. Increased osteocytic 1,25(OH)2D production, triggered by renal malfunction, may represent a "primary defensive response" to protect the organism from ectopic calcification by increasing sclerostin and suppressing BMP2 production.

Poly(ADP-ribose) polymerase 1 accelerates vascular calcification by upregulating Runx2.

Vascular calcification is highly prevalent in end-stage renal diseases and is predictive of cardiovascular events and mortality. Poly(ADP-ribose) polymerase 1 (PARP1) inhibition or deletion is vasoprotective in several disease models. Here we show that PARP activity is increased in radial artery samples from patients with chronic renal failure, in arteries from uraemic rats, and in calcified vascular smooth muscle cells (VSMCs) in vitro. PARP1 deficiency blocks, whereas PARP1 overexpression exacerbates, the transdifferentiation of VSMCs from a contractile to an osteogenic phenotype, the expression of mineralization-regulating proteins, and calcium deposition. PARP1 promotes Runx2 expression, and Runx2 deficiency offsets the pro-calcifying effects of PARP1. Activated PARP1 suppresses miRNA-204 expression via the IL-6/STAT3 pathway and thus relieves the repression of its target, Runx2, resulting in increased Runx2 protein. Together, these results suggest that PARP1 counteracts vascular calcification and that therapeutic agents that influence PARP1 activity may be of benefit to treat vascular calcification.

Effects of lactulose on renal function and gut microbiota in adenine-induced chronic kidney disease rats.

BACKGROUND: Constipation is frequently observed in patients with chronic kidney disease (CKD). Lactulose is expected to improve the intestinal environment by stimulating bowel movements as a disaccharide laxative and prebiotic. We studied the effect of lactulose on renal function in adenine-induced CKD rats and monitored uremic toxins and gut microbiota. METHODS: Wistar/ST male rats (10-week-old) were fed 0.75% adenine-containing diet for 3 weeks to induce CKD. Then, they were divided into three groups and fed as follows: control, normal diet; and 3.0- and 7.5-Lac, 3.0% and 7.5% lactulose-containing diets, respectively, for 4 weeks. Normal diet group was fed normal diet for 7 weeks. The rats were observed for parameters including renal function, uremic toxins, and gut microbiota. RESULTS: The control group showed significantly higher serum creatinine (sCr) and blood urea nitrogen (BUN) 3 weeks after adenine feeding than at baseline, with a 8.5-fold increase in serum indoxyl sulfate (IS). After switching to 4 weeks of normal diet following adenine feeding, the sCr and BUN in control group remained high with a further increase in serum IS. In addition, tubulointerstitial fibrosis area was increased in control group. On the other hand, 3.0- and 7.5-Lac groups improved sCr and BUN levels, and suppressed tubulointerstitial fibrosis, suggesting preventing of CKD progression by lactulose. Lac groups also lowered level of serum IS and proportions of gut microbiota producing IS precursor. CONCLUSION: Lactulose modifies gut microbiota and ameliorates CKD progression by suppressing uremic toxin production.

Excessive salt intake increases peritoneal solute transport rate via local tonicity-responsive enhancer binding protein in subtotal nephrectomized mice.

BACKGROUND: High peritoneal transport is associated with high mortality and technical failure in peritoneal dialysis (PD). Baseline peritoneal solute transport rate (PSTR) as measured by the peritoneal equilibration test (PET) within 6 months after PD initiation varies between patients. Sodium is reported to be stored in the skin or muscle of dialysis patients. This study investigated whether excessive salt intake in uremic mice caused peritoneal alterations without exposure to PD fluid. METHODS: Sham-operated (Sham) and subtotal nephrectomized (Nx) mice were randomly given tap water or 1% sodium chloride (NaCl)-containing water for 8 weeks. PET was then performed to evaluate peritoneal function. Human mesothelial cell line Met-5A was used for in vitro studies. RESULTS: We observed higher PSTR in Nx mice with 1% NaCl-containing drinking water (Nx + salt) compared with those with tap water (Nx + water), along with enhanced angiogenesis and inflammation in the peritoneum. Blockade of interleukin (IL)-6 signaling rescued peritoneal transport function in Nx + salt mice. In cultured Met-5A, additional NaCl in the medium upregulated IL-6 as well as vascular endothelial growth factor-A, associated with increased expression and nuclear translocation of tonicity-responsive enhancer binding protein (TonEBP). Knockdown of TonEBP lowered the induction caused by high tonicity. Peritoneal TonEBP expression was higher in Nx + salt mice, while removal of high-salt diet lowered TonEBP level and improved peritoneal transport function. CONCLUSIONS: Excessive dietary salt intake caused peritoneal membrane functional and structural changes under uremic status. TonEBP regulated hypertonicity-related inflammatory changes and might play a crucial role in high baseline peritoneal transport.

Effect of uremic toxin-indoxyl sulfate on the skeletal system.

Chronic kidney disease-mineral bone disorders (CKD-MBD) exhibit abnormalities in the circulating mineral levels, vitamin D metabolism, and parathyroid function that contribute to the formation of a bone lesion. The uremic toxin, indoxyl sulfate (IS), accumulates in the blood in cases of renal failure and leads to bone loss. The bone and renal responses to the action of the parathyroid hormone (PTH) are progressively decreased in CKD in spite of increasing PTH levels, a condition commonly called PTH resistance. There is a high prevalence of low bone turnover or adynamic bone disease in the early stages of CKD. This could be due to the inhibition of bone turnover, such as in PTH resistance, reduced active vitamin D levels, diabetes, aluminum, and, increased IS. With an increase in IS, there is a decrease in the osteoblast Wnt/b-catenin signaling and increase in the expression of Wnt signaling inhibitors, such as sclerostin and Dickkopf-1 (DKK1). Thus, a majority of early CKD patients exhibit deterioration of bone quality owing to the action of IS, this scenario could be termed uremic osteoporosis. However, this mechanism is complicated and not fully understood. With progressive deterioration in the renal function, IS accumulates along with persistent PTH secretion, potentially leading to high-turnover bone disease because high serum PTH levels have the ability of overriding peripheral PTH resistance and other inhibitory factors of bone formation. Finally, it leads to deterioration in bone quantity with prominent bone resorption in end stage renal disease. Uremic toxins adsorbents may decelerate oxidative stress and improve bone health in CKD patients. This review article focuses on IS and bone loss in CKD patients.

Review of pentosidine and pyrraline in food and chemical models: formation, potential risks and determination.

Pyrraline and pentosidine are advanced Maillard reaction products derived from the reaction of glucose with the lysine amino group on proteins. They have been implicated in uremia, diabetes, and related complications, including inflammation, retinopathy, and nephropathy. This review focuses on the formation mechanism, human potential risks, and detections of pentosidine and pyrraline and lays the foundation for further study of pentosidine and pyrraline. © 2017 Society of Chemical Industry.

Effects of growth hormone treatment on growth plate, bone, and mineral metabolism of young rats with uremia induced by adenine.

BackgroundIn a model of growth retardation secondary to chronic kidney disease (CKD) induced by adenine, this study explores the effects of growth hormone (GH) therapy on growth plate and mineral metabolism.MethodsWeaning female rats receiving a 0.5% adenine diet during 21 days, untreated (AD) or treated with GH (ADGH) for 1 week, were compared with control rats receiving normal diet, either ad libitum or pair-fed with AD animals. AD and ADGH rats had similarly elevated serum concentrations of urea nitrogen, parathyroid hormone (PTH), and fibroblast growth factor 23 (FGF23).ResultsUremia induced by adenine caused growth retardation and disturbed growth cartilage chondrocyte hypertrophy. We demonstrated marked expression of aquaporin 1 in the growth plate, but its immunohistochemical signal and the expression levels of other proteins potentially related with chondrocyte enlargement, such as Na-K-2Cl cotransporter, insulin-like growth factor 1 (IGF-1), and IGF-1 receptor, were not different among the four groups of rats. The distribution pattern of vascular endothelial growth factor was also similar. AD rats developed femur bone structure abnormalities analyzed by micro-computerized tomography.ConclusionGH treatment accelerated longitudinal growth velocity, stimulated the proliferation and enlargement of chondrocytes, and did not modify the elevated serum PTH or FGF23 concentrations or the abnormal bone structure.

Acute and subacute oral toxicity of periodate salts in rats.

Periodate salts are being developed as potential replacements for perchlorate due to potential health hazards associated with exposure to perchlorate. The aim of this study was to investigate acute and subacute effects of periodate salts in rats. Acute oral toxicity of potassium and sodium periodate was determined using the Sequential Stage-Wise Probit method. The LD50 for potassium periodate was 732 (95% CI = 539-838, slope = 13.4) and 685 mg/kg (95% CI = 580-809, slope = 10.6) for females and males, respectively. The LD50 for sodium periodate was 318 (95% CI = 292-347, slope = 24.3) and 741 mg/kg (95% CI = 704-779, slope = 31.2) for females and males, respectively. In the subacute study, rats were administered sodium periodate at five doses (1/16 LD50 up to LD50) or distilled water for 14-days via oral gavage. Female rats in the 318 mg/kg-day group and male rats in the 185, 370, and 741 mg/kg-day groups exhibited moribundity, kidney toxicity, uremia, and a stress response. BMDL10s of 17.2 and 33.7 mg/kg-day were derived for females and males, respectively. Comparison with the NOAEL for perchlorate-induced thyroid toxicity in rats (0.009 mg/kg-day) suggests sodium periodate is less toxic than perchlorate on a subacute basis.

Pharmacological effects of Vitamin C & E on Diclofenac Sodium intoxicated Rats.

OBJECTIVE: The aim of this study was to evaluate the probable protective effect of vitamin C and vitamin E on diclofenac-induced acute nephrotoxicity using biochemical, molecular and histopathological examination in rats following administration of diclofenac sodium (50mg/kg, I.M). METHODS: Ninety male Wister rats were allotted in six equal groups. Rats in the 1st group (control group) were injected with physiological saline, while rats in the 2nd group (C-group) were given vitamin C (100mg/kg orally via stomach tube) for 5 successive days. The 3rd group (E-group) was given vitamin E (250mg/kg orally in diet) for 5 successive days. Rats in the 4th group (D-group) were injected by diclofenac sodium (50mg/kg, I.M) for 5 successive days. The 5th group (DvC-group) was given diclofenac sodium (50mg/kg, I.M) and vitamin C (100mg/kg orally via stomach tube) for 5 successive days. Rats in the 6th group (DvE-group) were given diclofenac sodium (50mg/kg, I.M) and vitamin E (250mg/kg orally in diet) for 5 successive days. Blood samples were collected two days post treatment (1st week of experiment), 2nd and 4th week of the experiment for assessment of urea, creatinine, malondialdehyde, nitric oxide and superoxide dismutase activities. At the end of 4th week, rats were sacrificed and kidneys were excised for biochemical analyses, histopathological evaluation and determination of kidney interleukin-1ß, interleukin-18, demsin and nepherin expressions in by reverse transcriptase-polymerase chain reaction (RT-PCR). RESULTS: The results showed that, diclofenac induced severe kidney damage as indicated by histopathological changes and increased serum oxidative stress parameters. Behavioral changes were monitored; a significant increase in uremia in intoxicated animals was also noted indicating that diclofenac sodium provoked kidney damage in rats. Application of vitamin C (DvC-group) and vitamin E (DvE-group) were found to improve the abovementioned abnormalities. CONCLUSION: The present data suggest that, vitamin C and vitamin E might play an important role in reducing oxidative stress and kidney damage induced by diclofenac sodium.

Urea transporters and sweat response to uremia.

In humans, urea is excreted in sweat, largely through the eccrine sweat gland. The urea concentration in human sweat is elevated when compared to blood urea nitrogen. The sweat urea nitrogen (UN) of patients with end-stage kidney disease (ESRD) is increased when compared with healthy humans. The ability to produce sweat is maintained in the overwhelming majority of ESRD patients. A comprehensive literature review found no reports of sweat UN neither in healthy rodents nor in rodent models of chronic kidney disease (CKD). Therefore, this study measured sweat UN concentrations in healthy and uremic rats. Uninephrectomy followed by renal artery ligation was used to remove 5/6 of renal function. Rats were then fed a high-protein diet to induce uremia. Pilocarpine was used to induce sweating. Sweat droplets were collected under oil. Sweat UN was measured with a urease assay. Serum UN was measured using a fluorescent ortho-pthalaldehyde reaction. Immunohistochemistry (IHC) was accomplished with a horseradish peroxidase and diaminobenzidine technique. Sweat UN in uremic rats was elevated greater than two times compared to healthy pair-fed controls (220 ± 17 and 91 ± 15 mmol/L, respectively). Post hoc analysis showed a significant difference between male and female uremic sweat UN (279 ± 38 and 177 ± 11 mmol/L, respectively.) IHC shows, for the first time, the presence of the urea transporters UT-B and UT-A2 in both healthy and uremic rat cutaneous structures. Future studies will use this model to elucidate how rat sweat UN and other solute excretion is altered by commonly prescribed diuretics.