Biomedical subjects

A Davit

Publications and source records attributed to A Davit.

3 recordsLinked to original sources

PubMed2005

Mycophenolate mofetil and roscovitine decrease cyclin expression and increase p27(kip1) expression in anti Thy1 mesangial proliferative nephritis.

The response of mesangial cells to a phlogistic challenge includes cell proliferation and mesangial matrix expansion. Cell proliferation is a highly regulated process which includes enhancing factors such as cyclins, cyclin dependent kinases, and inhibitory proteins, such as p27(kip1). The aim of the study was to evaluate the effects of Mycophenolate mofetil (MMF), and roscovitine (R), on the cell cycle regulatory system when administered in the florid phase of the experimental model of mesangial proliferative nephritis induced by the anti Thy-1 antigen monoclonal antibody. Three days after nephritis induction, different groups were given MMF and R. Rats treated with MMF or R showed a slight decrease in mesangial proliferation and matrix expansion. Samples of cortical tissue were tested by 'real time' RT-PCR in order to study gene expression of cyclins B, D1, D2, D3, E, and the cyclin inhibitor p27(kip1). Localization of mRNA was evaluated by in situ hybridization. Real time RT-PCR analysis showed a significant decrease in cyclins B, D1, D2, and D3 in rats treated with either MMF or R as compared to controls. Both MMF and R treatment induced a significant increase in p27(kip1) mRNA expression. In situ hybridization showed a mesangial-endothelial expression pattern in glomeruli. The number of labelled cells per glomerulus, the number of positive glomeruli in each examined slide as well as cyclin D2 and D3 signal intensity was significantly lower in rats treated with MMF or R as compared to controls, whereas MMF or R treatment up-regulated p27(kip1) mRNA expression. Immunohistochemical evaluation of p27(kip1) aimed to examine the influence of MMF or R on protein expression confirmed up-regulation.

Animals↗

PubMed2003

Dehydroepiandrosterone reduces expression and activity of BACE in NT2 neurons exposed to oxidative stress.

Recently, we showed that oxidative stress activates the expression and activity of the beta-site AbetaPP-cleaving enzyme (BACE), an aspartyl protease responsible for the beta-secretase cleavage of AbetaPP. The identification of compounds able to prevent the induction of this event is an important goal of therapeutic strategies for Alzheimer's disease (AD). Dehydroepiandrosterone (DHEA) is an adrenal steroid that improves a variety of functions in the central nervous system. Moreover, a series of evidence suggests that DHEA displays antioxidant properties in different experimental models. In the present paper we show that pretreatment with DHEA is able to rescue the increase of mRNA expression, protein levels, and activity of BACE, produced by oxidative stress in NT2 neurons. BACE, being the enzyme that initiates the production of Abeta, is a drug target for AD. Our results imply that DHEA administration may slow down the AD pathological process, lowering Abeta accumulation.

Amyloid Precursor Protein Secretases↗

PubMed2000

Resveratrol depresses the growth of colorectal aberrant crypt foci by affecting bax and p21(CIP) expression.

We investigated whether resveratrol (RV) affects azoxymethane (AOM)-induced colon carcinogenesis, by administering RV (200 microg/kg/day in drinking water) to male F344 rats for 100 days, beginning 10 days before carcinogen treatment (two weekly doses of 15 mg/kg AOM). Aberrant crypt foci (ACF) were isolated and proliferation, apoptosis and expression of the cell cycle genes bax and p21 were determined. RV significantly reduced the number of ACF/colon [25.7 +/- 3.6 (mean +/- SEM) versus 39.4 +/- 3.3 in controls; P < 0.01] and their multiplicity (2.7 +/- 0.3 versus 4.9 +/- 0.6 in controls; P < 0.01), and also abolished large ACF. In RV-treated rats, bax expression was enhanced in ACF but not in the surrounding mucosa. In both controls and RV-treated rats, proliferation was higher in ACF than in normal mucosa. p21 was expressed in ACF of controls and of RV-treated rats and in normal mucosa of controls, but was lost in normal mucosa of RV-treated animals. In conclusion, the results suggest a protective role of RV in colon carcinogenesis with a mechanism involving changes in bax and p21 expression.

Animals↗