Effect of administration of clofibrate and clofenapate on kidney mitochondria of the rat

Abstract is not available.

Oxidation of succinate in heart, brain, and kidney mitochondria in hypobaria and hypoxia

Exposure of rats to hypobaric stress for periods of up to 36 h caused a consistent change in the succinate-NT reductase activity of the heart mitochondria whereas there was no significant change in the activities of either succinate dehydrogenase and succinate-NT reductase of the brain and the kidney. Mitochondrial succinate dehydrogenase of the heart, the brain and the kidney was activated 2- to 7-fold with the substrate and malonate. The activations obtained with oxalate, citrate and dinitrophenol were relatively lower in comparison to succinate and malonate. Benzohydroquinone and 2-nitrophenol had no stimulatory effect on the heart, the brain and the kidney mitochondria. THE ACTIVATIONS OBTAINED WITH THE VARIOUS EFFECTORS PARTIALLY (OR COMPLETELY IN THE CASE OF SUCCINATE) REVERSED ON WASHING THE MITOCHONDRIAL SAMPLES WITH THE SUCROSE HOMOGENIZING MEDIUM. The effect of ubiquinol, which also activated the enzyme, was only partially reversed after the second preincubation with succinate in the brain and the kidney whereas in the heart the activity was fully reversed. The increased activity of succinate dehydrogenase obtained with ATP and ADP was further enhanced by Mg2+ exclusively in the brain mitochondria, suggesting the possibility of Mg2+-AIP complex as the active species. Succinate-NT reductase of the heart, the brain and the kidney mitochondria showed a high activation with ubiquinone whereas its reduced form had no stimulatory effect.

Binding and regulatory properties of phosphofructokinase from swine kidney

The influence of fructose 2,6-bisphosphate on the activation of purified swine kidney phosphofructokinase as a function of the concentration of fructose 6P, ATP and citrate was investigated. The purified enzyme was nearly completely inhibited in the presence of 2 mM ATP. The addition of 20 nM fructose 2,6-P2 reversed the inhibition and restored more than 80% of the activity. In the absence of fructose 2,6-P2 the reaction showed a sigmoidal dependence on fructose-6-phosphate. The addition of 10 nM fructose 2,6-bisphosphate decreased the K0.5 for fructose 6-phosphate from 3 mM to 0.4 mM in the presence of 1.5 mM ATP. These results clearly show that fructose 2,6-bisphosphate increases the affinity of the enzyme for fructose 6-phosphate and decreases the inhibitory effect of ATP. The extent of inhibition by citrate was also significantly decreased in the presence of fructose 2,6-phosphate. The influence of various effectors of phosphofructokinase on the binding of ATP and fructose 6-P to the enzyme was examined in gel filtration studies. It was found that kidney phosphofructokinase binds 5.6 moles of fructose 6-P per mole of enzyme, which corresponds to about one site per subunit of tetrameric enzyme. The KD for fructose 6-P was 13 microM and in the presence of 0.5 mM ATP it increased to 27 microM. The addition of 0.3 mM citrate also increased the KD for fructose 6-P to about 40 microM. AMP, 10 microM, decreased the KD to 5 microM and the addition of fructose 2,6-phosphate decreased the KD for fructose 6-P to 0.9 microM. The addition of these compounds did not effect the maximal amount of fructose 6-P bound to the enzyme, which indicated that the binding site for these compounds might be near, but was not identical to the fructose 6-P binding site. The enzyme bound a maximum of about 12.5 moles of ATP per mole, which corresponds to 3 moles per subunit. The KD of the site with the highest affinity for ATP was 4 microM, and it increased to 15 microM in the presence of fructose 2,6-bisphosphate. The addition of 50 microM fructose 1,6-bisphosphate increased the KD for ATP to 5.9 microM. AMP increased the KD to 5.9 microM whereas 0.3 mM citrate decreased the KD for ATP to about 2 microM.(ABSTRACT TRUNCATED AT 400 WORDS).

Role of lipid peroxidation in impairment of mitochondrial function at complex I by methyl isocyanate treatment of rats in vivo

The subcutaneous administration of methyl isocyanate (MIC) in 1.0 LD50 dose in rats caused a significant effect on hepatic mitochondrial function only at complex I region of the respiratory chain. MIC administration at 1.0 LD50 dose also resulted in significant increases in malondialdehyde and ferrous ion concentration in liver mitochondria. It is suggested that the augmented lipid peroxidation in hepatic mitochondria, catalyzed by iron, possibly mobilized from intracellular stores leads to the inhibition of enzymes of mitochondrial respiration at complex I region, in vivo, in rats receiving a lethal dose of MIC subcutaneously.

Structure and activity cyclase activated of OK-GC: A kidney receptor-guanylate cyclase activated by guanylin peptides

Uroguanylin, guanylin, and lymphoguanylin are small peptides that activate renal and intestinal receptor guanylate cyclases (GC). They are structurally similar to bacterial heat-stable enterotoxins (ST) that cause secretory diarrhea. Uroguanylin, guanylin, and ST elicit natriuresis, kaliuresis, and diuresis by direct actions on kidney GC receptors. A 3,762-bp cDNA characterizing a uroguanylin/guanylin/ST receptor was isolated from opossum kidney (OK) cell RNA/cDNA. This kidney cDNA (OK-GC) encodes a mature protein containing 1,049 residues sharing 72.4�75.8% identity with rat, human, and porcine forms of intestinal GC-C receptors. COS or HEK-293 cells expressing OK-GC receptor protein were activated by uroguanylin, guanylin, or ST13 peptides. The 3.8-kb OK-GC mRNA transcript is most abundant in the kidney cortex and intestinal mucosa, with lower mRNA levels observed in urinary bladder, adrenal gland, and myocardium and with no detectable transcripts in skin or stomach mucosa. We propose that OK-GC receptor GC participates in a renal mechanism of action for uroguanylin and/or guanylin in the physiological regulation of urinary sodium, potassium, and water excretion. This renal tubular receptor GC may be a target for circulating uroguanylin in an endocrine link between the intestine and kidney and/or participate in an intrarenal paracrine mechanism for regulation of kidney function via the intracellular second messenger, cGMP.

Structure and activity of OK-GC: a kidney receptor guanylate cyclase activated by guanylin peptides

Uroguanylin, guanylin, and lymphoguanylin are small peptides that activate renal and intestinal receptor guanylate cyclases (GC). They are structurally similar to bacterial heat-stable enterotoxins (ST) that cause secretory diarrhea. Uroguanylin, guanylin, and ST elicit natriuresis, kaliuresis, and diuresis by direct actions on kidney GC receptors. A 3,762-bp cDNA characterizing a uroguanylin/guanylin/ST receptor was isolated from opossum kidney (OK) cell RNA/cDNA. This kidney cDNA (OK-GC) encodes a mature protein containing 1,049 residues sharing 72.4-75.8% identity with rat, human, and porcine forms of intestinal GC-C receptors. COS or HEK-293 cells expressing OK-GC receptor protein were activated by uroguanylin, guanylin, or ST13 peptides. The 3.8-kb OK-GC mRNA transcript is most abundant in the kidney cortex and intestinal mucosa, with lower mRNA levels observed in urinary bladder, adrenal gland, and myocardium and with no detectable transcripts in skin or stomach mucosa. We propose that OK-GC receptor GC participates in a renal mechanism of action for uroguanylin and/or guanylin in the physiological regulation of urinary sodium, potassium, and water excretion. This renal tubular receptor GC may be a target for circulating uroguanylin in an endocrine link between the intestine and kidney and/or participate in an intrarenal paracrine mechanism for regulation of kidney function via the intracellular second messenger, cGMP.

Cooperative Regulation of NOTCH1 Protein-Phosphatidylinositol 3-Kinase (PI3K) Signaling by NOD1, NOD2, and TLR2 Receptors Renders Enhanced Refractoriness to Transforming Growth Factor-beta (TGF-beta)- or Cytotoxic T-lymphocyte Antigen 4 (CTLA-4)-mediated Impairment of Human Dendritic Cell Maturation

Dendritic cells (DCs) as sentinels of the immune system are important for eliciting both primary and secondary immune responses to a plethora of microbial pathogens. Cooperative stimulation of a complex set of pattern-recognition receptors, including TLR2 and nucleotide-binding oligomerization domain (NOD)-like receptors on DCs, acts as a rate-limiting factor in determining the initiation and mounting of the robust immune response. It underscores the need for ``decoding'' these multiple receptor interactions. In this study, we demonstrate that TLR2 and NOD receptors cooperatively regulate functional maturation of human DCs. Intriguingly, synergistic stimulation of TLR2 and NOD receptors renders enhanced refractoriness to TGF-beta- or CTLA-4-mediated impairment of human DC maturation. Signaling perturbation data suggest that NOTCH1-PI3K signaling dynamics assume critical importance in TLR2- and NOD receptor-mediated surmounting of CTLA-4- and TGF-beta -suppressed maturation of human DCs. Interestingly, the NOTCH1-PI3K signaling axis holds the capacity to regulate DC functions by virtue of PKC delta-MAPK-dependent activation of NF-kappa B. This study provides mechanistic and functional insights into TLR2-and NOD receptor-mediated regulation of DC functions and unravels NOTCH1-PI3K as a signaling cohort for TLR2 and NOD receptors. These findings serve in building a conceptual foundation for the design of improved strategies for adjuvants and immunotherapies against infectious diseases.

Hypoxia-Mediated Impairment of the Mitochondrial Respiratory Chain Inhibits the Bactericidal Activity of Macrophages

In infected tissues oxygen tensions are low. As innate immune cells have to operate under these conditions, we analyzed the ability of macrophages (M phi) to kill Escherichia coli or Staphylococcus aureus in a hypoxic microenvironment. Oxygen restriction did not promote intracellular bacterial growth but did impair the bactericidal activity of the host cells against both pathogens. This correlated with a decreased production of reactive oxygen intermediates (ROI) and reactive nitrogen intermediates. Experiments with phagocyte NADPH oxidase (PHOX) and inducible NO synthase (NOS2) double-deficient M phi revealed that in E. coli- or S. aureus-infected cells the reduced antibacterial activity during hypoxia was either entirely or partially independent of the diminished PHOX and NOS2 activity. Hypoxia impaired the mitochondrial activity of infected M phi. Inhibition of the mitochondrial respiratory chain activity during normoxia (using rotenone or antimycin A) completely or partially mimicked the defective antibacterial activity observed in hypoxic E. coli-or S. aureus-infected wild-type M phi, respectively. Accordingly, inhibition of the respiratory chain of S. aureus-infected, normoxic PHOX-/- NOS2(-/-) M phi further raised the bacterial burden of the cells, which reached the level measured in hypoxic PHOX-/- NOS2(-/-) M phi cultures. Our data demonstrate that the reduced killing of S. aureus or E. coli during hypoxia is not simply due to a lack of PHOX and NOS2 activity but partially or completely results from an impaired mitochondrial antibacterial effector function. Since pharmacological inhibition of the respiratory chain raised the generation of ROI but nevertheless phenocopied the effect of hypoxia, ROI can be excluded as the mechanism underlying the antimicrobial activity of mitochondria.

Extracting Three Dimensional Surface Model of Human Kidney from the Visible Human Data Set using Free Software

Three dimensional digital model of a representative human kidney is needed for a surgical simulator that is capable of simulating a laparoscopic surgery involving kidney. Buying a three dimensional computer model of a representative human kidney, or reconstructing a human kidney from an image sequence using commercial software, both involve (sometimes significant amount of) money. In this paper, author has shown that one can obtain a three dimensional surface model of human kidney by making use of images from the Visible Human Data Set and a few free software packages (ImageJ, ITK-SNAP, and MeshLab in particular). Images from the Visible Human Data Set, and the software packages used here, both do not cost anything. Hence, the practice of extracting the geometry of a representative human kidney for free, as illustrated in the present work, could be a free alternative to the use of expensive commercial software or to the purchase of a digital model.

Non-Syndromic Hearing Impairment in India: High Allelic Heterogeneity among Mutations in TMPRSS3, TMC1, USHIC, CDH23 and TMIE

Mutations in the autosomal genes TMPRSS3, TMC1, USHIC, CDH23 and TMIE are known to cause hereditary hearing loss. To study the contribution of these genes to autosomal recessive, non-syndromic hearing loss (ARNSHL) in India, we examined 374 families with the disorder to identify potential mutations. We found four mutations in TMPRSS3, eight in TMC1, ten in USHIC, eight in CDH23 and three in TMIE. Of the 33 potentially pathogenic variants identified in these genes, 23 were new and the remaining have been previously reported. Collectively, mutations in these five genes contribute to about one-tenth of ARNSHL among the families examined. New mutations detected in this study extend the allelic heterogeneity of the genes and provide several additional variants for structure-function correlation studies. These findings have implications for early DNA-based detection of deafness and genetic counseling of affected families in the Indian subcontinent.

Differential expression of estrogen receptor alpha in the embryonic adrenal-kidney-gonadal complex of the oviparous lizard, Calotes versicolor (Daud.)

Estrogen signalling is critical for ovarian differentiation in reptiles with temperature-dependent sex determination (TSD). To elucidate the involvement of estrogen in this process, adrenal-kidney-gonadal (AKG) expression of estrogen receptor (ER alpha) was studied at female-producing temperature (FPT) in the developing embryos of the lizard, Calotes versicolor which exhibits a distinct pattern of TSD. The eggs of this lizard were incubated at 31.5 +/- 0.5 degrees C (100% FPT). The torso of embryos containing adrenal-kidney-gonadal complex (AKG) was collected during different stages of development and subjected to Western blotting and immunohistochemistry analysis. The ER alpha, antibody recognized two protein bands with apparent molecular weight similar to 55 and similar to 45 kDa in the total protein extracts of embryonic AKG complex of C. versicolor. The observed results suggest the occurrence of isoforms of ER alpha. The differential expression of two different protein isoforms may reveal their distinct role in cell proliferation during gonadal differentiation. This is the first report to reveal two isoforms of the ER alpha in a reptile during development. Immunohistochemical studies reveal a weak, but specific, cytoplasmic ER alpha immunostaining exclusively in the AKG during late thermo-sensitive period suggesting the responsiveness of AKG to estrogens before gonadal differentiation at FPT. Further, cytoplasmic as well as nuclear expression of ER alpha in the medulla and in oogonia of the cortex (faint activity) at gonadal differentiation stage suggests that the onset of gonadal estrogen activity coincides with sexual differentiation of gonad. Intensity and pattern of the immunoreactions of ER alpha in the medullary region at FPT suggest endogenous production of estrogen which may act in a paracrine fashion to induce neighboring cells into ovarian differentiation pathway. (C) 2014 Elsevier Inc. All rights reserved.