Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:1.3.5.1 (succinate dehydrogenase)
 8,177 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Freshly isolated rabbit proximal tubules (PT), confluent primary rabbit proximal tubule cultures (PTC) and LLC-PK1 cells were characterised. Brushborder enzyme activities were lower in PTC than in LLC-PK1: ratios were 0.026 for alkaline phosphatase (AP), 0.458 for alanine aminopeptidase (AAP) and 0.514 for gamma-glutamyl transpeptidase (GGT). PT/PTC ratios were 79.7 for AP, 7.96 for AAP and 3.45 for GGT. Specific activities of hexokinase (HK) and lactate dehydrogenase (LDH) were high in cultured cells as compared to PT: PT/PTC ratios were 0.063 and 0.033, while PTC/LLC-PK1 ratios were 0.406 and 1.19 for HK and LDH respectively. PTC/LLC-PK1 ratios were 2.21 for Na/K ATPase, 2.07 for succinate dehydrogenase, 1.12 for cathepsin B, 0.607 for N-acetyl-beta-D-glucosaminidase and 8.98 for glutathione-S-transferase. Adenylate cyclase response to parathormone (PTH), was similar in PTC and PT, but stimulated/basal ratios were higher in PT than in PTC. LLC-PK1 cells were stimulated by thyrocalcitonin (SCT), arginin-vasopressin (AVP) and PTH; stimulated/basal ratios ranked AVP greater than PTH greater than SCT. Differences between both types of cultures affect the choice of in vitro model for nephrotoxicity studies.
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PMID:Adenylate cyclase responses and biochemical characterization of primary rabbit proximal tubular cell cultures and LLC-PK1 cells. 228 70

Among kidney tubular epithelial cell types, proximal tubule cells are one of the major renal targets for xenobiotics. Several in vitro culture models have been proposed for use of proximal tubule cells for in vitro pharmacotoxicology studies. This paper reports a comparative study of the response to cephaloridine exposure of two established cell lines from pig (LLC-PK1) and rabbit (LLC-RK1) kidneys and primary cultures of rat and rabbit proximal tubule cells. These cultured cells were first compared for their levels of activity of alpha-methylglucopyranoside transport, alkaline phosphatase, succinate dehydrogenase, and NADPH cytochrome c reductase, their glutathione-dependent activity levels, and their adenylate cyclase response pattern to stimulation by PTH and AVP. The results presented show major phenotypic differences between these four cellular models. The differences observed in glutathione-dependent mechanism activities and regulation may in part be responsible for the variability of the responses of these four cellular models when exposed to cephaloridine.
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PMID:Comparative impact of cephaloridine on glutathione and related enzymes in LLC-PK1, LLC-RK1, and primary cultures of rat and rabbit proximal tubule cells. 903 21

Renal damage caused by therapeutic treatment with cyclosporine A has been well documented. Clinical experiences have shown that cyclosporine A nephrotoxicity is determined by interstitial fibrosis with tubular atrophy. However, the exact mechanism by which this drug causes nephrotoxicity has not yet been clarified. This study used an in vitro model in an attempt to identify the cellular mechanisms underlying kidney cyclosporine A damage. We used two cell lines with the characteristics of proximal and distal tubule cells (pig kidney proximal tubular epithelial cell line [LLC-PK1] and Madin-Darby canine kidney cell line [MDCK]. The cell lines were treated with cyclosporine A for 24 h. After the treatment, the cells were stained with Trypan Blue to estimate cell viability and processed by histochemical reactions to evaluate their cellular metabolism. Four enzymes (acid phosphatase, alkaline phosphatase, lactate dehydrogenase and succinate dehydrogenase) were considered. The cell viability assay showed that the LLC-PK1 cell line was more sensitive to cyclosporine A than MDCK. Remarkably, the LLC-PK1 cells disappeared with cyclosporine A treatment. As for the hydrolytic enzymes, only acid phosphatases showed an increased positivity in the treated LLC-PK1 cells. Similarly, lactate dehydrogenase showed a different activity histochemically. No statistically significant alterations were observed in the succinate dehydrogenase reaction. The cyclosporine A-treated MDCK cell lines did not show any difference in either their hydrolytic or succinate dehydrogenase enzyme positivity with respect to the control line. In contrast, there was a significant increase in lactate dehydrogenase activity. This study allowed the possible mechanism of cyclosporine A-induced damage in renal tubular cells to be evaluated. The enzymatic changes happened rapidly (during the 24 h of treatment), suggesting that this alteration was one of the steps by which cyclosporine A induced toxicity. Moreover, since acid phosphatase is a marker of protein catabolism, the variation in the activity of this enzyme, in the LLC-PK1 line only, showed that cyclosporine can induce alterations leading to cellular toxicity. The modifications in lactate dehydrogenase activity, in both lines, suggested that this drug caused cell stress, inducing the production of lactic acid from glucose in the presence of oxygen. In conclusion, cyclosporine A treatment may force LLC-PK1 and MDCK cells to use anaerobic glycolysis preferentially. Further, these enzyme alterations may represent an epiphenomenon or a consequence of cyclosporine A toxicity.
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PMID:Cyclosporine A-induced toxicity in two renal cell culture models (LLC-PK1 and MDCK). 1236 97

Polymer therapeutics are being designed for lysosomotropic, endosomotropic and transcellular drug delivery. Their appropriate intracellular routing is thus crucial for successful use. For example, polymer-anticancer drug conjugates susceptible to lysosomal enzyme degradation will never deliver their drug payload unless they encounter the appropriate activating enzymes. Many studies use confocal microscopy to monitor intracellular fate, but there is a pressing need for more quantitative methods able to define intracellular compartmentation over time. Only then will it be possible to optimise the next generation of polymer therapeutics for specific applications. The aim of this study was to establish a subcellular fractionation method for B16F10 murine melanoma cells and subsequently to use it to define the intracellular trafficking of N-(2-hydroxyproplylmethacrylamide) (HPMA) copolymer-bound doxorubicin (PK1). Free doxorubicin was used as a reference. The cell cracker method was used to achieve cell breakage and optimised to reproducibly achieve approximately 90% breakage efficiency. This ensured that subsequent subcellular fractionation experiments were representative for the whole cell population. To characterise the subcellular fractions obtained by differential centrifugation, DNA (nuclei), succinate dehydrogenase (mitochondria), N-acetyl-beta-glucosaminidase (lysosomes), alkaline phosphatase (plasma membrane) and lactate dehydrogenase (cytosol) were selected as markers and their assay was carefully validated. The relative specific activity (RSA) of the fractions obtained from B16F10 cells were: nuclei (2.2), mitochondria (4.1), lysosomes (3.7) and cytosol (2.5). When used to study the intracellular distribution at non-toxic concentrations of PK1 and doxorubicin, time-dependent accumulation of PK1 in lysosomes was evident and the expected nuclear localisation of free doxorubicin was seen. Live cell fluorescence microscopy and confocal co-localisation studies gave qualitative corroboration of these results, but by using this method, we were unable to accurately define organelle localisation. In conclusion, the B16F10 subcellular fractionation method developed here provides a useful tool to allow comparison of the intracellular trafficking of other polymer conjugates.
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PMID:Establishment of subcellular fractionation techniques to monitor the intracellular fate of polymer therapeutics I. Differential centrifugation fractionation B16F10 cells and use to study the intracellular fate of HPMA copolymer - doxorubicin. 1709 38