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Enhanced Accumulation (enhanced + accumulation)
Selected AbstractsXanthine oxidase inhibitor allopurinol attenuates the development of diabetic cardiomyopathyJOURNAL OF CELLULAR AND MOLECULAR MEDICINE, Issue 8b 2009Mohanraj Rajesh Abstract In this study, we investigated the effect of the xanthine oxidase (XO) inhibitor, allopurinol (ALP), on cardiac dysfunction, oxidative-nitrosative stress, apoptosis, poly(ADP-ribose) polymerase (PARP) activity and fibrosis associated with diabetic cardiomyopathy in mice. Diabetes was induced in C57/BL6 mice by injection of streptozotocin. Control and diabetic animals were treated with ALP or placebo. Left ventricular systolic and diastolic functions were measured by pressure,volume system 10 weeks after established diabetes. Myocardial XO, p22phox, p40phox, p47phox, gp91phox, iNOS, eNOS mRNA and/or protein levels, ROS and nitrotyrosine (NT) formation, caspase3/7 and PARP activity, chromatin fragmentation and various markers of fibrosis (collagen-1, TGF-,, CTGF, fibronectin) were measured using molecular biology and biochemistry methods or immunohistochemistry. Diabetes was characterized by increased myocardial, liver and serum XO activity (but not expression), increased myocardial ROS generation, p22phox, p40phox, p47phox, p91phox mRNA expression, iNOS (but not eNOS) expression, NT generation, caspase 3/7 and PARP activity/expression, chromatin fragmentation and fibrosis (enhanced accumulation of collagen, TGF-,, CTGF and fibronectin), and declined systolic and diastolic myocardial performance. ALP attenuated the diabetes-induced increased myocardial, liver and serum XO activity, myocardial ROS, NT generation, iNOS expression, apoptosis, PARP activity and fibrosis, which were accompanied by improved systolic (measured by the evaluation of both load-dependent and independent indices of myocardial contractility) and diastolic performance of the hearts of treated diabetic animals. Thus, XO inhibition with ALP improves type 1 diabetes-induced cardiac dysfunction by decreasing oxidative/nitrosative stress and fibrosis, which may have important clinical implications for the treatment and prevention of diabetic cardiomyopathy and vascular dysfunction. [source] Effectiveness of extracellular lactate/pyruvate for sustaining synaptic vesicle proton gradient generation and vesicular accumulation of GABAJOURNAL OF NEUROCHEMISTRY, Issue 3 2006A. S. Tarasenko Abstract The effects of extracellular monocarboxylates pyruvate and lactate on membrane potentials, acidification and neurotransmitter filling of synaptic vesicles were investigated in experiments with rat brain synaptosomes using [3H]GABA and fluorescent dyes, potential-sensitive rhodamine 6G and pH-sensitive acridine orange. In experiments investigating accumulation of acridine orange in synaptic vesicles within the synaptosomes, monocarboxylates, similarly to glucose, ensured generation of the vesicle proton gradient by available and recycled vesicles, and pyruvate demonstrated the highest efficacy. An increase in the level of proton gradient correlated with enhanced accumulation of [3H]GABA in synaptic vesicles and resulted in enlarged exocytosis and attenuated the transporter-mediated [3H]GABA release. Pyruvate added to glucose-contained medium caused more active binding of rhodamine 6G by synaptosomes that reflected mitochondrial membrane hyperpolarization, and this intensification of nerve terminal energy metabolism resulted in an increase in total ATP content by ,25%. Pyruvate also prolonged the state of metabolic competence of nerve terminal preparations, keeping the mitochondrial potential and synaptic vesicle proton gradient at steady levels over a long period of time. Thus, besides glucose, the extracellular monocarboxylates pyruvate and lactate can provide sufficient support of energy-dependent processes in isolated nerve terminals, allowing effective functioning of neurotransmitter release and reuptake systems. [source] ACCUMULATION OF OLEIC ACID IN HAEMATOCOCCUS PLUVIALIS (CHLOROPHYCEAE) UNDER NITROGEN STARVATION OR HIGH LIGHT IS CORRELATED WITH THAT OF ASTAXANTHIN ESTERS1JOURNAL OF PHYCOLOGY, Issue 2 2002Mirash Zhekisheva The chlorophyte Haematococcus pluvialis accumulates large quantities of astaxanthin under stress conditions. Under either nitrogen starvation or high light, the production of each picogram of astaxanthin was accompanied by that of 5 or 3,4 pg of fatty acids, respectively. In both cases, the newly formed fatty acids, consisting mostly of oleic (up to 34% of fatty acids in comparison with 13% in the control), palmitic, and linoleic acids, were deposited mostly in triacylglycerols. Furthermore, the enhanced accumulation of oleic acid was linearily correlated with that of astaxanthin. Astaxanthin, which is mostly monoesterified, is deposited in globules made of triacylglycerols. We suggest that the production of oleic acid-rich triacylglycerols on the one hand and the esterification of astaxanthin on the other hand enable the oil globules to maintain the high content of astaxanthin esters. [source] Microarray analysis of chitin elicitation in Arabidopsis thalianaMOLECULAR PLANT PATHOLOGY, Issue 5 2002Katrina M. Ramonell Summary Chitin oligomers, released from fungal cell walls by endochitinase, induce defence and related cellular responses in many plants. However, little is known about chitin responses in the model plant Arabidopsis. We describe here a large-scale characterization of gene expression patterns in Arabidopsis in response to chitin treatment using an Arabidopsis microarray consisting of 2375 EST clones representing putative defence-related and regulatory genes. Transcript levels for 71 ESTs, representing 61 genes, were altered three-fold or more in chitin-treated seedlings relative to control seedlings. A number of transcripts exhibited altered accumulation as early as 10 min after exposure to chitin, representing some of the earliest changes in gene expression observed in chitin-treated plants. Included among the 61 genes were those that have been reported to be elicited by various pathogen-related stimuli in other plants. Additional genes, including genes of unknown function, were also identified, broadening our understanding of chitin-elicited responses. Among transcripts with enhanced accumulation, one cluster was enriched in genes with both the W-box promoter element and a novel regulatory element. In addition, a number of transcripts had decreased abundance, encoding several proteins involved in cell wall strengthening and wall deposition. The chalcone synthase promoter element was identified in the upstream regions of these genes, suggesting that pathogen signals may suppress the expression of some genes. These data indicate that Arabidopsis should be an excellent model to elucidate the mechanisms of chitin elicitation in plant defence. [source] Transient expression of a vacuolar peroxidase increases susceptibility of epidermal barley cells to powdery mildewMOLECULAR PLANT PATHOLOGY, Issue 6 2001Brian Kåre Kristensen summary The expression of genes encoding the peroxidases, Prx7 and Prx8, is induced in barley leaf tissue after inoculation with the barley powdery mildew fungus, Blumeria graminis f.sp. hordei (DC) Speer (Bgh). The role of these peroxidases in general barley defence responses against fungal attack was investigated using a transient expression system. Colonization frequencies of Bgh on cells transfected with Prx7 or Prx8 expression-, mutant- or fusion-DNA constructs were compared to the frequencies on cells expressing a ,-glucuronidase (GUS) control construct. Twice the number of powdery mildew colonies were observed on cells expressing Prx7 as compared to control cells. Introduction of either mutant or truncated versions of Prx7 showed that decreased resistance against Bgh was dependent on the presence of the C-terminal signal peptide required for correct subcellular targeting, but not affected significantly by mutations in the catalytic centre. No impact on Bgh performance was observed after the introduction of Prx8 or mutant constructs. An enhanced accumulation of the apoplastic Prx8 was verified by immunocytology. These results indicate a more complex role of peroxidases in defence responses than was previously suspected. [source] | ||||||||||