Search results for "ATS"

Stable expression of rat cytochrome P-450IIB1 cDNA in Chinese hamster cells (V79) and metabolic activation of aflatoxin B1.

1988

V79 Chinese hamster fibroblasts are widely used for mutagenicity testing but have the serious limitation that they do not express cytochromes P-450, which are needed for the activation of many promutagens to mutagenic metabolites. A full-length cDNA clone encoding the monooxygenase cytochrome P-450IIB1 under control of the simian virus 40 early promoter was constructed and cointroduced with the selection marker neomycin phosphotransferase (conferring resistance to G418) into V79 Chinese hamster cells. G418-resistant cells were selected, established as cell lines, and tested for cytochrome P-450IIB1 expression and enzymatic activity. Two cell lines (SD1 and SD3) were found that stably produc…

Sermón que en la solemne fiesta de Acción de Gracias celebrada en la Iglesia Catedral de Valencia el día 19 de enero del año 1812, por la gloriosa en…

Changes in metabolism of inorganic polyphosphate in rat tissues and human cells during development and apoptosis

1997

Age-dependent studies show that the amount of inorganic polyphosphate in rat brain strongly increases after birth. Maximal levels were found in 12-months old animals. Thereafter, the concentration of total polyphosphate decreases to about 50%. This decrease in the concentration of total polyphosphate is due to a decrease in the amount of insoluble, long-chain polyphosphates. The amount of soluble, long-chain polyphosphates does not change significantly in the course of ageing. In rat embryos and newborns, mainly soluble polyphosphates could be detected. In rat liver, the age-dependent changes are less pronounced. The changes in polyphosphate level are accompanied by changes in exopolyphosph…

Impairment of intracellular antiviral defense with age: age-dependent changes in expression of interferon-induced and double-stranded RNA-activated 2…

1995

The 2',5'-oligoadenylate (2-5A) system is involved in the defense of mammalian cells against virus infection. In a previous study [25], we demonstrated that the activities of the enzymes which synthesize and degrade 2-5A [2-5A synthetase (2-5OAS) and 2',3'-exoribonuclease] and of the enzyme that is activated by 2-5A (ribonuclease L) change during aging and development in different tissues of rat. The age-dependent decrease in 2-5OAS activity and increase in 2-5A nuclease activity results in a decrease in the cellular 2-5A content, suggesting that the efficiency of the antiviral 2-5A system is impaired in aged rats. Here we determined the age-dependent changes in the level of mRNA coding for…

Correlation between superoxide dismutase, glutathione peroxidase and catalase in isolated rat hepatocytes during fetal development

1981

Abstract Superoxide dismutase, glutathione peroxidase and catalase activities were determined in isolated fetal rat hepatocytes of various ages and compared with the values of neonatal and adult cells. The developmental pattern of superoxide dismutase and glutathione peroxidase were very similar with a low constant activity in the fetal cells and a postnatal burst. On the contrary catalase begins to increase already since the 18th day of the fetal life. The results suggest a functional correlation of superoxide dismutase and glutathione peroxidase in the antioxidative enzyme defense of liver cells.

Aging modifies receptor expression but not muscular contractile response to angiotensin II in rat jejunum

2022

AbstractThe involvement of renin-angiotensin system in the modulation of gut motility and age-related changes in mRNA expression of angiotensin (Ang II) receptors (ATR) are well accepted. We aimed to characterize, in vitro, the contractile responses induced by Ang II, in jejunum from young (3–6 weeks old) and old rats (≥ 1 year old), to evaluate possible functional differences associated to changes in receptor expression. Mechanical responses to Ang II were examined in vitro as changes in isometric tension. ATR expression was assessed by qRT-PCR. Ang II induced a contractile effect, antagonized by losartan, AT1R antagonist, and increased by PD123319, AT2R antagonist, as well by neural block…

A simplified framework to optimize MRI contrast preparation

2018

PURPOSE This article proposes a rigorous optimal control framework for the design of preparation schemes that optimize MRI contrast based on relaxation time differences. METHODS Compared to previous optimal contrast preparation schemes, a drastic reduction of the optimization parameter number is performed. The preparation scheme is defined as a combination of several block pulses whose flip angles, phase terms and inter-pulse delays are optimized to control the magnetization evolution. RESULTS The proposed approach reduces the computation time of B 0 -robust preparation schemes to around a minute (whereas several hours were required with previous schemes), with negligible performance loss. …

Neuroprotective effects of behavioural training and nicotine on age-related deficits in spatial learning.

2006

Studies in humans and animals show a clear decline in spatial memory with age and several approaches have been adopted to alleviate this impairment. The purpose of our review is to assess the studies that have suggested the possible neuroprotective actions of behavioural training and nicotine-applied both independently and in conjunction-on age-related deficits in spatial learning. Both spatial pretraining and nonspatial experiences influence an animal's performance in spatial tasks. In aged rats, the experience of training in the water maze task increases the number of newly generated neurons in the hippocampus. The neuroprotective effects of nicotine have been demonstrated in both in-vitr…

Cognitive deficits in aged rats correlate with levels of l-arginine, not with nNOS expression or 3,4-DAP-evoked transmitter release in the frontopari…

2005

Aging is associated with altered neurotransmitter function in the brain. In this study, we measured release parameters for acetylcholine (ACh), norepinephrine and serotonin in the frontoparietal cortex of young and aged rats. We also determined cortical amino acid concentrations and nitric oxide (NO) synthase function. Prior to sacrifice, the rats had been tested for Morris water-maze performance. In aged, compared with young rats, we observed a reduction in both uptake of choline and acetylcholine release. Serotonin release and L-arginine concentrations (a precursor of NO) showed an aging-related increase; however, L-citrulline/L-arginine ratios were decreased in aged rats. Moreover, while…

β-Amyloid-induced activation of Caspase-3 in primary cultures of rat neurons

2000

It is known that beta-amyloid peptide (Abeta) contributes to the neurodegeneration in Alzheimer's disease (AD) and operates through activation of an apoptotic pathway. Apoptotic signal is driven by a family of cysteine proteases called caspases. The beta-amyloid precursor protein (APP) is directly and efficiently cleaved by caspases during apoptosis, resulting in elevated beta-amyloid peptide formation. Cerebellar neurons from rat pups were treated with the aged Abeta(25-35) at 1 and 5 microM and fluorescence assays of caspase activity performed over 4 days. We observed an increase in caspase activity after 48 h treatment in both 1 and 5 microM treated cells, then (72-96 h) caspase activity…