Biomedical research in developing countries. I--The Algerian case (1993-1998).

Biomedical articles emerging from Algeria between 1993 an 1998 were analysed in order to evaluate the scientific output. By developing a search strategy based on complementary bibliographic databases, 221 articles were retrieved, which geographic location, research topic, language, journal name and impact factor were analysed. International collaborations resulted in a profound change of the publication profile in terms of language, journal impact factor, and above all a change in research interests.

De novo synthesis of arginine and ornithine from citrulline in human colon carcinoma cells: metabolic fate of L-ornithine.

In human colon carcinoma cells (HT-29 cells), L-arginine is the common precursor of L-ornithine which generates polyamines strictly necessary for cellular growth, and nitric oxide which has a strong antiproliferative activity. We show here that proliferative HT-29 cells possess the capacity for de novo synthesis of L-arginine from L-citrulline, but not from L-ornithine. L-Ornithine is apparently not an L-arginine precursor due to the absence of any detectable ornithine carbamoyltransferase activity.

Alpha-difluoromethylornithine (DFMO) as a potent arginase activity inhibitor in human colon carcinoma cells.

Alpha-difluoromethylornithine (DFMO) is commonly used as a specific ornithine decarboxylase (ODC, EC4.1.1.

Differential inhibitory effects of three nitric oxide donors on ornithine decarboxylase activity in human colon carcinoma cells.

Ornithine decarboxylase (ODC, EC 4.1.1.

Effects of L-valine on growth and polyamine metabolism in human colon carcinoma cells.

HT-29 cells, originating from a human colon carcinoma, can proliferate in standard culture conditions with an absolute requirement for polyamines. The major precursor provided in the culture medium for polyamine biosynthesis is L-arginine. L-Arginine conversion to L-ornithine by arginase is followed by stepwise conversion of this latter amino acid to putrescine, spermidine and spermine.

Sodium nitroprusside inhibits proliferation and putrescine synthesis in human colon carcinoma cells.

In human colon carcinoma HT-29 Glc(-/+) cells, L-arginine is the common precursor of polyamines which are absolutely necessary for cellular proliferation and nitric oxide (NO) with reported anti-proliferative activity. The aim of the present work was to test the effect of the NO donor sodium nitroprusside (SNP) on polyamine synthesis and cellular growth in HT-29 cells. SNP in the micromolar range inhibits cellular putrescine synthesis and this effect is greatly reversed by haemoglobin, supporting the view that the effect of SNP is related to the generation of NO.

Metabolism of L-arginine through polyamine and nitric oxide synthase pathways in proliferative or differentiated human colon carcinoma cells.

HT-29 Glc-/+ cells originate from a human colon adenocarcinoma. These cells have been selected in a glucose-free culture medium and switched back in a glucose-containing medium. In this condition, they can spontaneously differentiate after confluency in enterocyte-like cells according to the activity of the brush-border associated hydrolase dipeptidyl peptidase IV.