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1
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Respiratory surveillance and Ca2+-ATPase enzyme activity studies of Clarias gariepinus exposed to acute toxicity of cyanide

100%
Oseni K.
International Letters of Natural Sciences
|
2016
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tom 50
Potassium cyanide, a highly contaminating and toxic aquatic ecosystems pollutant was investigated for acute toxicity on the freshwater fish Clarias gariepinus. Its effect on the Ca2+ - ATPase activities in the liver, gills, muscle and intestinal tissues and oxygen consumption index was studied. Short-term toxicity test was carried out by static renewal bioassay test over a 96 h period using a lethal concentration (LC50) value of 0.361mg/mL. Potassium cyanide was highly toxic to the animal tested. Results reveal that normal respiratory activity (O2 consumption) of the fish was significantly affected and there was significant decreased in the Ca2+ - ATPase activities at the end of exposure periods (24, 48, 72 and 96 h). Correlation analysis reveals a strong relationship between oxygen consumption index and ATPase enzyme activity of Clarias gariepinus exposed to the toxicant. This study reflects the toxic effect of potassium cyanide to the freshwater fish, Clarias gariepinus and suggestion on the possible application of Ca2+ -ATPase activities and oxygen consumption index as possible biomarkers for early detection of cyanide poisoning in aquatic bodies.
2

Influence of the sagittal advancement of mandibulae on myofibrillar ATPase activity and myosin heavy chain content in the masticatory muscles of pigs

100%
Gedrange T., Lupp A., Kirsch C., Harzer W., Klinger R.
Folia Histochemica et Cytobiologica
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2002
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tom 40
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nr 3
3

Spectrophotometric method for the determination of renal ouabain-sensitive Hplus, Kplus-ATPase activity

100%
Beltowski J., Wojcicka G.
Acta Biochimica Polonica
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2002
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tom 49
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nr 2
The aim of this work was to develop a method for renal H+,K+-ATPase measurement based on the previously used Na+ ,K+ -ATPase assay (Bełtowski et al.: J Physiol Pharmacol.; 1998, 49: 625-37). ATPase activity was assessed by measuring the amount of inorganic phosphate liberated from ATP by isolated microsomal fraction. Both ouabain-sensitive and ouabain-resistant K+ -stimulated and Na+ -independent ATPase activity was detected in the renal cortex and medulla. These activities were blocked by 0.2 mM imidazolpyridine derivative, Sch 28080. The method for ouabain- sensitive H+ ,K -ATPase assay is characterized by good reproducibility, linearity and recovery. In contrast, the assay for ouabain-resistant H ,K -ATPase was unsatisfac­tory, probably due to low activity of this enzyme. Ouabain-sensitive H+ ,K+ -ATPase was stimulated by K + with Km of 0.26 ± 0.04 mM and 0.69 ±0.11 mM in cortex and me­dulla, respectively, and was inhibited by ouabain (Ki of 2.9 ± 0.3 uM in the renal cortex and 1.9 ± 0.4 uM in the renal medulla) and by Sch 28080 (Ki of 1.8 ± 0.5 uM and 2.5 ± 0.9 uM in cortex and medulla, respectively). We found that ouabain-sensitive H+ ,K+ -ATPase accounted for about 12% of total ouabain-sensitive activity in the Na+ ,K+-ATPase assay. Therefore, we suggest to use Sch 28080 during Na+,K+-ATPase measurement to block H+ ,K+ -ATPase and improve the assay specificity. Leptin ad­ministered intraperitoneally (1 mg/kg) decreased renal medullary Na+ ,K+ -ATPase ac­tivity by 32.1% at 1 h after injection but had no effect on H+ ,K+ -ATPase activity sug­gesting that the two renal ouabain-sensitive ATPases are separately regulated.
4

The Crabtree effect: a new look at the old problem

100%
Wojtczak L.
Acta Biochimica Polonica
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1996
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tom 43
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nr 2
Inhibition of respiration by glucose, known as the Crabtree effect, has been observed in several tumours and some other highly glycolytic cells and tissues. Among mechanisms proposed to explain this effect were: competition between glycolysis and respiration for ADP or for inorganic phosphate, change of intracellular pH, change in the permeability of mitochondrial membranes, specific regulatory behaviour of glycolytic enzymes, and specific enzyme topography within the cell. None of these proposals alone seems satisfactory. The present article describes the research carried out in the author's laboratory, pointing to the role of Ca2+ in the mechanism of the Crabtree effect This supposition is based on the following observations: (1) in Ehrlich ascites tumour cells glucose elicits a steady increase of the cytoplasmic concentration of free Ca2+; (2) isolated Ehrlich ascites mitochondria and mitochondria within digitonin-permeabilised cells, preloaded with Ca2+, exhibit a depression of State 3 respiration and lowering of the rate of ATP synthesis; (3) ATPase activity of toluene-permeabilised Ehrlich ascites mitochondria becomes substantially inhibited at micromolar concentrations of Ca2+; (4) Ca2+ potentiates the effect of the inhibitory subunit of F1F0-ATPase. These results allow to hypothesize on the following sequence of events: (1) glucose elevates the cytoplasmic concentration of Ca2+; (2) this elicits an increased accumulation of Ca2+ in mitochondria; (3) loading of mitochondria with Ca2+ leads to an increased association of the inhibitory subunit with F1F0 which results in (4) the inhibition of coupled respiration. The importance of these mechanisms for glycolytic and rapidly proliferating cells is discussed.
5
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In vivo and in vitro effects of hyperglycemia on Naplus-Kplus, Caplus2, Mgplus2-dependent ATPases activity in brain synaptosomes of aging rats

80%
Torlinska T., Grochowalska A., Kupisz J., Skoracka J., Kojo S.
Journal of Physiology and Pharmacology. Supplement
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2006
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tom 57
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nr 7
145-158
Cerebral metabolism of glucose, one of the determinants of tissue ATP level, is crucial for the CNS function. The activity of P-type pumps: Na+, K+-ATPase, Ca+2-ATPase and Mg+2-ATPase were examined in rat brain synaptosomes to determine if changes in the enzyme activity related to aging are potentially associated with alterations in glucose homeostasis. Male Wistar rats (newborn, 3- and 18-month-old) were sacrificed by decapitation and synaptic plasma membranes were isolated from brains. In vivo study demonstrated that 18-month-old rats were characterized by hyperglycemia, hyperinsulinemia and increased total antyoxidative status (TAS) level. These conditions had a different impact on activities of the ATPases tested in vivo: only the activity of Ca+2-ATPase decreased whereas that of Mg+2-ATPase increased significantly. In vitro experiments, prior incubation of isolated synaptosomes with glucose of concentrations corresponding to normoglycemia in vivo (4.5 - 6.5 mM), stimulated Ca+2-ATPase activity, whereas higher glucose concentrations (10.0 - 12.5 mM) inhibited significantly the enzyme activity. The most sensitive to hyperglycemia appeared Na+, K+-ATPase in old rats synaptosomes with the progressive decline starting at 6.5 mM glucose. The activity of Mg+2-ATPase was not inhibited in vitro even at high glucose concentrations that may explain the increased in vivo, activity of this enzyme in old, hyperglycemic rats.
6

Myosins and pathology: genetics and biology

80%
Redowicz M. J.
Acta Biochimica Polonica
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2002
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tom 49
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nr 4
This article summarizes current knowledge on the genetics and possible molecular mechanisms of human pathologies resulted from mutations within the genes encoding several myosin isoforms. Mutations within the genes encoding some myosin isoforms have been found to be responsible for blindness (myosins III and VIIA), deafness (myosins I, IIA, IIIA, VI, VIIA and XV) and familial hypertrophic cardiomyopathy (β cardiac myosin heavy chain and both the regulatory and essential light chains). Myosin III localizes predominantly to photoreceptor cells and is proved to be en­gaged in the vision process in Drosophila. In the inner ear, myosin I is postulated to play a role as an adaptive motor in the tip links of stereocilia of hair cells, myosin IIA seems to be responsible for stabilizing the contacts between adjacent inner ear hair cells, myosin VI plays a role as an intracellular motor transporting membrane structures within the hair cells while myo- sin VIIA most probably participates in forming links between neighbouring stereocilia and myosin XV probably stabilizes the stereocilia structure. About 30% of patients with familial hypertrophic cardiomyopathy have mutations within the genes encoding the β cardiac myosin heavy chain and both light chains that are grouped within the regions of myosin head crucial for its functions. The alter­ations lead to the destabilization of sarcomeres and to a decrease of the myosin ATPase activity and its ability to move actin filaments.
7

Correlation of myofibrillar ATPase activity and myosin heavy chain content in ventricular and atrial myocardium of fish heart

80%
Karasinski J., Sokalski A., Kilarski W.
Folia Histochemica et Cytobiologica
|
2001
|
tom 39
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nr 1
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