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Ken-ichi Inui - One of the best experts on this subject based on the ideXlab platform.
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analysis of regulatory polymorphisms in Organic Ion transporter genes slc22a in the kidney
Journal of Human Genetics, 2008Co-Authors: Ken Ogasawara, Masayo Aoki, Toshiya Katsura, Tomohiro Terada, Junichi Asaka, Hideyuki Motohashi, Osamu Ogawa, Tomomi Kamba, Ken-ichi InuiAbstract:Organic catIon transporters (OCTs) and Organic anIon transporters (OATs) (SLC22A family) play crucial roles in the renal secretIon of various drugs. Messengar ribonucleic acid (mRNA) expressIon of transporters can be a key factor regulating interindividual differences in drug pharmacokinetics. However, the source of variatIons in mRNA levels of transporters is unclear. In this study, we focused on single nucleotide polymorphisms (SNP) in the promoter regIon [regulatory SNPs (rSNPs)] as candidates for the factor regulating mRNA levels of SLC22A. We sequenced the promoter regIons of OCT2 and OAT1–4 in 63 patients and investigated the effects of the identified rSNPs on transcriptIonal activities and mRNA expressIon. In the OCT2 promoter regIon, one deletIon polymorphism (−578_−576delAAG) was identified; −578_−576delAAG significantly reduced OCT2 promoter activity (p < 0.05), and carriers of −578_−576delAAG tend to have lower OCT2 mRNA levels, but the difference is not significant. There was no rSNP in the OAT1 and OAT2 genes. The five rSNPs of OAT3 and one rSNP of OAT4 were unlikely to influence mRNA expressIon and promoter activity. This is the first study to investigate the influences of rSNPs on mRNA expressIon of SLC22A in the kidney and to identify a regulatory polymorphism affecting OCT2 promoter activity.
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ExpressIon profiles of various transporters for oligopeptides, amino acids and Organic Ions along the human digestive tract
Biochemical Pharmacology, 2005Co-Authors: Tomohiro Terada, Toshiya Katsura, Yutaka Shimada, Koshiro Kishimoto, Takaki Sakurai, Hisashi Onodera, Masayuki Imamura, Ken-ichi InuiAbstract:Abstract Various transporters such as H + /peptide cotransporter PEPT1 are expressed in the intestine, and play important physiological and pharmacological roles in the body. Present study was performed to examine the expressIon profile of 20 kinds of transporters (PEPT1 and 2, P-glycoprotein, amino acid transporters and Organic Ion transporters) along the human digestive tract, especially focusing on PEPT1. Using normal mucosal specimens, real-time polymerase chain reactIons were carried out. Immunoblot analyses were also performed for PEPT1 expressIon. PEPT1 mRNA was highly expressed in the small intestine (duodenum > jejunum > ileum) compared to other tissues, and some patients showed a significant level of expressIon in the stomach. The expressIonal pattern of PEPT1 in the stomach and histological diagnosis indicated that gastric PEPT1 originated from the intestinal metaplasia. The amino acid transporters showed unique mRNA expressIon levels and distributIons in the digestive tract. For example, the expressIon levels of B 0 AT1, a Na + -dependent and chloride-independent neutral amino acid transporter, were increased from the duodenum to ileum, which pattern is completely inverted to that for PEPT1. There is little expressIon of Organic Ion transporters except for Organic catIon/carnitine transporter OCTN2. In conclusIon, PEPT1 was abundantly expressed in the small intestine, and the reciprocal expressIon of PEPT1 and B 0 AT1 may serve for the efficient absorptIon of protein digestive products.
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Restored expressIon and activity of Organic Ion transporters rOAT1, rOAT3 and rOCT2 after hyperuricemia in the rat kidney
Biochemical Pharmacology, 2005Co-Authors: Yasushi Habu, Atsushi Fukatsu, Ikuko Yano, Masahiro Okuda, Ken-ichi InuiAbstract:Abstract We previously reported that in hyperuricemic rats, renal impairment occurred and Organic Ion transport activity decreased, accompanied with a specific decrease in the expressIon of rat Organic anIon transporters, rOAT1 and rOAT3, and Organic catIon transporter, rOCT2. In the present study, we investigated the reversibility of the Organic Ion transport activity and expressIon of Organic Ion transporters (slc22a) during recovery from hyperuricemia. Hyperuricemia was induced by the administratIon of a chow containing uric acid and oxonic acid, an inhibitor of uric acid metabolism. Four days after discontinuance of the chow, the plasma uric acid concentratIon returned to the normal level, and renal functIons such as creatinine clearance and BUN levels were restored, although the recovery of tubulointerstitial injury was varied in sites of the kidney. Basolateral uptake of p -aminohippurate (PAH) and tetraethylammonium (TEA), and both protein and mRNA levels of rOAT1, rOAT3 and rOCT2 in the kidney gradually improved during 14 days of recovery from hyperuricemia. Basolateral PAH transport showed a higher correlatIon with the protein level of rOAT1 ( r 2 = 0.80) than rOAT3 ( r 2 = 0.34), whereas basolateral TEA transport showed a strong correlatIon with rOCT2 protein ( r 2 = 0.91). The plasma testosterone concentratIon, which is a dominant factor in the regulatIon of rOCT2, was gradually restored during the recovery from hyperuricemia, but the correlatIon between the plasma testosterone level and rOCT2 protein expressIon in the kidney was not significant. These results suggest that the regulatIon of Organic Ion transporters, rOAT1, rOAT3 and rOCT2, by hyperuricemia is reversible, and the Organic Ion transport activity restores according to the expressIon levels of these transporters.
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metformin is a superior substrate for renal Organic catIon transporter oct2 rather than hepatic oct1
Drug Metabolism and Pharmacokinetics, 2005Co-Authors: Naoko Kimura, Toshiya Katsura, Satohiro Masuda, Masahiro Okuda, Yuko Tanihara, Ken-ichi InuiAbstract:Summary: Although metformin, a catIonic agent for type II diabetes, shows its pharmacological effect in the liver, the drug is mainly eliminated into urine. The tissue selectivity based on the functIon of drug transporters is unclear. In the present study, the transport of metformin was examined using HEK293 cells transiently transfected with five human renal Organic Ion transporter cDNAs. Human OCT1 and OCT2, but not OAT1, OAT3 or OCT2-A, stimulated the uptake. A kinetic analysis of metformin transport demonstrated that the amount of plasmid cDNA for transfectIon was also important parameter to the quantitative elucidatIon of functIonal characteristics of transporters, and both human and rat OCT2 had about a 10- and 100-fold greater capacity to transport metformin than did OCT1, respectively. In male rats, the mRNA expressIon level of rOCT2 in the whole kidneys was 8-fold greater than that of rOCT1 in the whole liver. The in vivo distributIon of metformin in rats revealed that the expressIon level of renal OCT2 was a key factor in the control of the concentrative accumulatIon of metformin in the kidney. These findings suggest that metformin is a superior substrate for renal OCT2 rather than hepatic OCT1, and renal OCT2 plays a dominant role for metformin pharmacokinetics.
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Decreased activity of basolateral Organic Ion transports in hyperuricemic rat kidney: roles of Organic Ion transporters, rOAT1, rOAT3 and rOCT2.
Biochemical Pharmacology, 2003Co-Authors: Yasushi Habu, Atsushi Fukatsu, Hideyuki Saito, Ikuko Yano, Masahiro Okuda, Ayako Takeuchi, Ken-ichi InuiAbstract:Abstract We investigated Organic anIon and catIon transport activity and the expressIon of several Organic Ion transporters in hyperuricemic rat kidney. Feeding oxonic acid, an inhibitor of uric acid metabolism, and uric acid for 10 days significantly increased plasma uric acid level. Plasma creatinine and blood urea nitrogen concentratIons also increased in hyperuricemic rats, indicating impaired renal functIon. The accumulatIon of Organic anIons, p-aminohippurate (PAH) and methotrexate, and catIons, tetraethylammonium (TEA) and cimetidine, into renal slices was markedly decreased, suggesting decreased transport activity for Organic anIons and catIons at the basolateral membrane in the kidney. The expressIon levels of basolateral Organic anIon transporters rOAT1 and rOAT3, and Organic catIon transporter, rOCT2, significantly decreased in hyperuricemic rat kidney as assessed by mRNA and protein levels. In contrast, the expressIon of rOCT1 was unaltered by hyperuricemia at both mRNA and protein levels. Moreover, the mRNA expressIon of kidney-specific Organic anIon transporters, OAT-K1 and OAT-K2, and Organic anIon transporting polypeptide (oatp) 1, which localize at the brush-border membrane in the kidney, was unchanged in hyperuricemic rats. In conclusIon, we showed decreased basolateral Organic anIon and catIon transport activity, accompanied by a specific decrease in rOAT1, rOAT3 and rOCT2 expressIon in hyperuricemic rat kidney. These phenomena partly contribute to the changed renal dispositIon of Organic anIons and catIons in hyperuricemia.
Masahiro Okuda - One of the best experts on this subject based on the ideXlab platform.
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Restored expressIon and activity of Organic Ion transporters rOAT1, rOAT3 and rOCT2 after hyperuricemia in the rat kidney
Biochemical Pharmacology, 2005Co-Authors: Yasushi Habu, Atsushi Fukatsu, Ikuko Yano, Masahiro Okuda, Ken-ichi InuiAbstract:Abstract We previously reported that in hyperuricemic rats, renal impairment occurred and Organic Ion transport activity decreased, accompanied with a specific decrease in the expressIon of rat Organic anIon transporters, rOAT1 and rOAT3, and Organic catIon transporter, rOCT2. In the present study, we investigated the reversibility of the Organic Ion transport activity and expressIon of Organic Ion transporters (slc22a) during recovery from hyperuricemia. Hyperuricemia was induced by the administratIon of a chow containing uric acid and oxonic acid, an inhibitor of uric acid metabolism. Four days after discontinuance of the chow, the plasma uric acid concentratIon returned to the normal level, and renal functIons such as creatinine clearance and BUN levels were restored, although the recovery of tubulointerstitial injury was varied in sites of the kidney. Basolateral uptake of p -aminohippurate (PAH) and tetraethylammonium (TEA), and both protein and mRNA levels of rOAT1, rOAT3 and rOCT2 in the kidney gradually improved during 14 days of recovery from hyperuricemia. Basolateral PAH transport showed a higher correlatIon with the protein level of rOAT1 ( r 2 = 0.80) than rOAT3 ( r 2 = 0.34), whereas basolateral TEA transport showed a strong correlatIon with rOCT2 protein ( r 2 = 0.91). The plasma testosterone concentratIon, which is a dominant factor in the regulatIon of rOCT2, was gradually restored during the recovery from hyperuricemia, but the correlatIon between the plasma testosterone level and rOCT2 protein expressIon in the kidney was not significant. These results suggest that the regulatIon of Organic Ion transporters, rOAT1, rOAT3 and rOCT2, by hyperuricemia is reversible, and the Organic Ion transport activity restores according to the expressIon levels of these transporters.
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metformin is a superior substrate for renal Organic catIon transporter oct2 rather than hepatic oct1
Drug Metabolism and Pharmacokinetics, 2005Co-Authors: Naoko Kimura, Toshiya Katsura, Satohiro Masuda, Masahiro Okuda, Yuko Tanihara, Ken-ichi InuiAbstract:Summary: Although metformin, a catIonic agent for type II diabetes, shows its pharmacological effect in the liver, the drug is mainly eliminated into urine. The tissue selectivity based on the functIon of drug transporters is unclear. In the present study, the transport of metformin was examined using HEK293 cells transiently transfected with five human renal Organic Ion transporter cDNAs. Human OCT1 and OCT2, but not OAT1, OAT3 or OCT2-A, stimulated the uptake. A kinetic analysis of metformin transport demonstrated that the amount of plasmid cDNA for transfectIon was also important parameter to the quantitative elucidatIon of functIonal characteristics of transporters, and both human and rat OCT2 had about a 10- and 100-fold greater capacity to transport metformin than did OCT1, respectively. In male rats, the mRNA expressIon level of rOCT2 in the whole kidneys was 8-fold greater than that of rOCT1 in the whole liver. The in vivo distributIon of metformin in rats revealed that the expressIon level of renal OCT2 was a key factor in the control of the concentrative accumulatIon of metformin in the kidney. These findings suggest that metformin is a superior substrate for renal OCT2 rather than hepatic OCT1, and renal OCT2 plays a dominant role for metformin pharmacokinetics.
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Decreased activity of basolateral Organic Ion transports in hyperuricemic rat kidney: roles of Organic Ion transporters, rOAT1, rOAT3 and rOCT2.
Biochemical Pharmacology, 2003Co-Authors: Yasushi Habu, Atsushi Fukatsu, Hideyuki Saito, Ikuko Yano, Masahiro Okuda, Ayako Takeuchi, Ken-ichi InuiAbstract:Abstract We investigated Organic anIon and catIon transport activity and the expressIon of several Organic Ion transporters in hyperuricemic rat kidney. Feeding oxonic acid, an inhibitor of uric acid metabolism, and uric acid for 10 days significantly increased plasma uric acid level. Plasma creatinine and blood urea nitrogen concentratIons also increased in hyperuricemic rats, indicating impaired renal functIon. The accumulatIon of Organic anIons, p-aminohippurate (PAH) and methotrexate, and catIons, tetraethylammonium (TEA) and cimetidine, into renal slices was markedly decreased, suggesting decreased transport activity for Organic anIons and catIons at the basolateral membrane in the kidney. The expressIon levels of basolateral Organic anIon transporters rOAT1 and rOAT3, and Organic catIon transporter, rOCT2, significantly decreased in hyperuricemic rat kidney as assessed by mRNA and protein levels. In contrast, the expressIon of rOCT1 was unaltered by hyperuricemia at both mRNA and protein levels. Moreover, the mRNA expressIon of kidney-specific Organic anIon transporters, OAT-K1 and OAT-K2, and Organic anIon transporting polypeptide (oatp) 1, which localize at the brush-border membrane in the kidney, was unchanged in hyperuricemic rats. In conclusIon, we showed decreased basolateral Organic anIon and catIon transport activity, accompanied by a specific decrease in rOAT1, rOAT3 and rOCT2 expressIon in hyperuricemic rat kidney. These phenomena partly contribute to the changed renal dispositIon of Organic anIons and catIons in hyperuricemia.
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Cellular and molecular mechanisms of renal tubular secretIon of Organic anIons and catIons
Clinical and Experimental Nephrology, 1998Co-Authors: Ken-ichi Inui, Masahiro OkudaAbstract:A wide variety of endogenous Organic Ions and xenobiotics are secreted into the urine via Organic anIon and catIon transport systems, expressed in brush-border and basolateral membranes of renal tubular cells. Using membrane vesicles isolated from the kidney, cultured renal epithelial cells, isolated renal tubules, and slices of renal cortex, extensive studies have been done regarding the mechanisms of renal tubular secretIon of Organic Ions. Basolateral entry of Organic anIons is mediated by the Organic anIon/dicarboxylate exchange system, whereas apical extrusIon of Organic anIons from epithelial cells is mediated by an anIon exchanger and/or by membrane potential-sensitive transport systems. Studies using membrane vesicles have made clear the fact that the basolateral transport of Organic catIons is stimulated by inside-negative membrane potential, whereas the transport of Organic catIons in brush-border membranes is achieved by a proton gradient. Trasport studies using cultured renal epithelial cells have shown other aspects of Organic Ion transport, such as regulatory mechanisms for transcellular transport of orgnaic anIons and catIons. The recent development of molecular techniques has greatly advanced our understanding of the molecular aspects of various transport processes. In 1994, a cDNA clone encoding the prototype Organic catIon transporter was isolated from rat kidney. Within the last 3 years, several Organic anIon and catIon transporters in the kidney have been identified by different cloning techniques. In this review, we describe the mechanisms mediating renal tubular secretIon of Organic anIons and catIons, including recent topics in this area.
Lingdong Kong - One of the best experts on this subject based on the ideXlab platform.
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quercetin regulates Organic Ion transporter and uromodulin expressIon and improves renal functIon in hyperuricemic mice
European Journal of Nutrition, 2012Co-Authors: Qinghua Hu, Ruiqing Jiao, Xing Wang, Xian Zhang, Lingdong KongAbstract:Background Renal Organic Ion transporters and uromodulin (UMOD) play the important roles in renal urate excretIon and functIon. Hyperuricemia is considered as a risk factor for the development of renal dysfunctIon. The flavonoid quercetin in diets exerts the hypouricemic and nephroprotective effects.
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Aristolochic acid-induced destructIon of Organic Ion transporters and fatty acid metabolic disorder in the kidney of rats.
Toxicology Letters, 2010Co-Authors: Jianmei Li, Ruiqing Jiao, Xing Wang, Yan Lu, Shui-juan Wang, Lingdong KongAbstract:Abstract Aristolochic acid (AA) nephropathy exhibits early proximal tubular injury and fatty acid metabolic disorder. In order to study the unrecognized abnormalities of Organic Ion transporters and fatty acid metabolism indicators in AA nephropathy, Wistar rats were orally administrated with vehicle, 10 and 20 mg/kg AA once daily for 7 days, respectively. At day 8, significant reductIon of body weight and right kidney weight, as well as elevatIon of plasma blood urea nitrogen (BUN) levels, renal long-chain fatty acids (LCFAs), non-esterified fatty acids (NEFA) and triglycerides (TG) contents were observed in AA-treated rats, accompanying with down-regulatIon of renal rOAT1/3, rOCT1/2 and rOCTN1/2 expressIons. OCTN2 particularly transports l- carnitine through cell membrane. AA treatment also induced a significant decrease of l -carnitine levels in renal cortex of rats. Down-regulatIon of peroxisome proliferator-activated receptor alpha (rPPARα) and carnitine acyltransferase 1 (rCPT1), and up-regulatIon of acetyl coenzyme A carboxylase 1/2 (rACC1/2) in renal cortex were detected in AA-treated rats. These results indicate that alteratIons of Organic Ion transportatIon and fatty acid metabolism are part of AA-induced nephropathy (AAN), contribute to the altered urinary metabolic profile and may lead to further proximal tubule injury in rats.
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Morin Improves Urate ExcretIon and Kidney FunctIon through RegulatIon of Renal Organic Ion Transporters in Hyperuricemic Mice
Journal of Pharmacy and Pharmaceutical Sciences, 2010Co-Authors: Cai-ping Wang, Xing Wang, Xian Zhang, Lingdong KongAbstract:Purpose. Morin (3,5,7,2′,4′-pentahydroxyflavone), a plant-derived flavonoid, has beneficial effects in animals with various diseases including hyperuricemia and renal dysfunctIon. Since the decreased renal excretIon of uric acid is the hallmark of hyperuricemia and renal dysfunctIon, here we studied the effects of oral morin administratIon on renal Organic Ion transporters in oxonate-induced hyperuricemic mice. Methods. The hyperuricemia in mice was induced by potassium oxonate. Uric acid and creatinine concentratIons in urine and serum, and fractIonal excretIon of uric acid (FEUA) were performed to evaluate urate handling. Changes in the expressIon levels of renal Organic Ion transporters were detected by Western blotting and semi-quantitative reverse transcriptIon polymerase chain reactIon (RT-PCR). Results. Morin treatment significantly reduced urinary uric acid/creatinine ratio and FEUA, resulting in the reductIon of serum uric acid levels in hyperuricemic mice. And kidney dysfunctIon was also improved after morin treatment in this model. Protein and mRNA levels of renal glucose transporter 9 (mGLUT9) and urate transporter 1 (mURAT1) were significantly decreased, and renal Organic anIon transporter (mOAT1) levels were remarkably increased in morin-treated hyperuricemic mice. Morin treatment also blocked down-regulatIon of renal Organic catIon and carnitine transporters (mOCT1, mOCT2, mOCTN1 and mOCTN2) in hyperuricemic mice. ConclusIon. These results suggest that morin exhibits uricosuric effect via suppressing urate reabsorptIon and promoting urate secretIon in the kidney of hyperuricemic mice and may help to attenuate deleterious effects of hyperuricemia with renal dysfunctIon.
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allopurinol rutin and quercetin attenuate hyperuricemia and renal dysfunctIon in rats induced by fructose intake renal Organic Ion transporter involvement
American Journal of Physiology-renal Physiology, 2009Co-Authors: Qinghua Hu, Jianmei Li, Chuang Wang, Dongmei Zhang, Lingdong KongAbstract:Fructose consumptIon has been recently related to an epidemic of metabolic syndrome, and hyperuricemia plays a pathogenic role in fructose-induced metabolic syndrome. Fructose-fed rats showed hyper...
Qinghua Hu - One of the best experts on this subject based on the ideXlab platform.
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Emodinol ameliorates urate nephropathy by regulating renal Organic Ion transporters and inhibiting immune inflammatory responses in rats
Biomedicine & Pharmacotherapy, 2017Co-Authors: Hui Wu, Mengze Zhou, Guo Lu, Zhonglin Yang, Hui Ji, Qinghua HuAbstract:Emodinol, 1β, 3β, 23-trihydroxyolean-12-en-28-acid, as the main active ingredient firstly extracted from the rhizomes of Elaeagus pungens by our Research Group, was identified with apparent uricosuric and nephroprotective effects in hyperuricemia mice in our previous study. This study aimed to investigate the renal protective effect of emodinol in urate nephropathy rats. Rats were orally administrated by combined adenine and ethambutol to induce urate nephropathy. Emodinol at various doses were administered intragastrically to urate nephropathy rats daily. Serum uric acid (Sur), serum creatinine (Scr) and blood urea nitrogen (BUN) levels, as well as Interleukin-1beta (IL-1β) and tumor necrosis factor- alpha (TNF-α) concentratIons in serum and kidney were determined. Renal protein expressIons of Organic Ion transporters, components of NLR pyrin domain containing 3 (NLRP3) inflammasome, as well as key factors involved in toll-like receptors (TLRs)/myeloid differentiatIon factor 88 (MyD88)/nuclear factor kappa B (NF-κB) signaling pathway were analyzed by western blot. Emodinol significantly decreased Sur, Scr and BUN levels in adenine and ethambutol − induced urate nephropathy rats. More importantly, emodinol reversed dys-expressIon of Organic Ion transporters, inhibited NLRP3 inflammsome activatIon and suppressed TLRs/MyD88/NF-κB signaling pathway in the kidneys of urate nephropathy rats. Consistently, dilated tubules and tubular UA crystal formatIon, as well as tubular interstitial inflammatory cells infiltratIon in kidneys of urate nephropathy rats were obviously attenuated by emodinol, accompanied by restored renal and serum inflammatory cytokines concentratIons. Taken together, the date suggested that emodinol ameliorated urate nephropathy by regulating renal Organic Ion transporters and inhibiting immune inflammatory responses in rats.
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quercetin regulates Organic Ion transporter and uromodulin expressIon and improves renal functIon in hyperuricemic mice
European Journal of Nutrition, 2012Co-Authors: Qinghua Hu, Ruiqing Jiao, Xing Wang, Xian Zhang, Lingdong KongAbstract:Background Renal Organic Ion transporters and uromodulin (UMOD) play the important roles in renal urate excretIon and functIon. Hyperuricemia is considered as a risk factor for the development of renal dysfunctIon. The flavonoid quercetin in diets exerts the hypouricemic and nephroprotective effects.
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allopurinol rutin and quercetin attenuate hyperuricemia and renal dysfunctIon in rats induced by fructose intake renal Organic Ion transporter involvement
American Journal of Physiology-renal Physiology, 2009Co-Authors: Qinghua Hu, Jianmei Li, Chuang Wang, Dongmei Zhang, Lingdong KongAbstract:Fructose consumptIon has been recently related to an epidemic of metabolic syndrome, and hyperuricemia plays a pathogenic role in fructose-induced metabolic syndrome. Fructose-fed rats showed hyper...
Peter J. Todd - One of the best experts on this subject based on the ideXlab platform.
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Organic Ion imaging of biological tissue with secondary Ion mass spectrometry and matrix assisted laser desorptIon IonizatIon
Journal of Mass Spectrometry, 2001Co-Authors: Peter J. Todd, Gregory T Schaaff, Pierre Chaurand, Richard M CaprioliAbstract:Organic secondary Ion mass spectrometry (SIMS) and matrix-assisted laser desorptIon/IonizatIon (MALDI) mass spectrometry can be used to produce molecular images of samples. This is achieved through IonizatIon from a clearly identified point on a flat sample, and performing a raster of the sample by moving the point of IonizatIon over the sample surface. The unique analytical capabilities of mass spectrometry for mapping a variety of biological samples at the tissue level are discussed. SIMS provides informatIon on the spatial distributIon of the elements and low molecular mass compounds as well as molecular structures on these compounds, while MALDI yields spatial informatIon about higher molecular mass compounds, including their distributIons in tissues at very low levels, as well as informatIon on the molecular structures of these compounds. ApplicatIon of these methods to analytical problems requires appropriate instrumentatIon, sample preparatIon methodology, and a data presentatIon usually in a three-coordinate plot where x and y are physical dimensIons of the sample and z is the signal amplitude. The use of imaging mass spectrometry is illustrated with several biological systems.
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A wide-angle secondary Ion probe for Organic Ion imaging
Journal of the American Society for Mass Spectrometry, 1991Co-Authors: Casey C. Grimm, R. T. Short, Peter J. ToddAbstract:A secondary Ion source has been developed for an Organic Ion microprobe capable of imaging samples up to 2 em in diameter. The source uses a focused 5 keY Cs^+ Ion beam which is rastered across the sample surface, and secondary Ions from each point on the sample are collected and formed into a low energy beam to be analyzed by a quadrupole mass filter. Dynamic emittance matching is employed to deflect Ions from off-axis points on the sample back onto the mass analyzer axis. Rastering and dynamic emittance matching are rapidly controlled by assembly language programs using an IBM/AT (80286) type computer. A low energy Ion monitor was used to tune and evaluate the secondary Ion source by providing a magnified cross-sectIonal image of the Ion beam at the source exit aperture. A well-focused and centered secondary Ion beam was obtained from each point on the sample, indicating that large-scale dynamic emittance matching with high collectIon efficiency is possible. Mass resolved images of grids and glycerol samples are shown to demonstrate the performance of the integrated secondary Ion source mass analyzer and control system.