Doxorubicin-induced alterations in kidney functioning,oxidative stress,DNA damage,and renal tissue morphology; Improvement by Acacia hydaspica tannin-rich ethyl acetate fraction

Doxorubicin (DOX) is an anthracycline drug used for cancer treatment. However, its treatment is contiguous with toxic effects. We examined the nephroprotective potential of A. hydaspica polyphenol-rich ethyl acetate extract (AHE) against DOX persuaded nephrotoxicity. 36 male Sprague Dawley rats were randomly assorted into 6 groups. Control group received saline; DOX group: 3 mg/kg b.w. dosage of DOX intraperitoneally for 6 weeks (single dose/week). In co-treatment groups, 200 and 400 mg/kg b.w AHE was given orally for 6 weeks in concomitant with DOX (3 mg/kg b.w, i.p. injection per week) respectively. Standard group received silymarin 400 mg/kg b.w daily + DOX (single dose/week). Biochemical kidney function tests, oxidative stress markers, genotoxicity, antioxidant enzyme status, and histopathological changes were examined. DOX caused significant body weight loss and decrease kidney weight. DOX-induced marked deterioration in renal function indicators in both urine and serum, i.e., PH, specific gravity, total protein, albumin, urea, creatinine, uric acid, globulin, blood urea nitrogen, etc. Also, DOX treatment increases renal tissue oxidative stress markers, while lower antioxidant enzymes in tissue along with degenerative alterations in the renal tissue compared to control rats. AHE co-treatment ameliorates DOX-prompted changes in serum and urine chemistry. Likewise, AHE treatment decreases sensitive markers of oxidative stress and prevented DNA damages by enhancing antioxidant enzyme levels. DOX induction in rats also caused DNA fragmentation which was restored by AHE co-treatment. Moreover, the histological observations evidenced that AHE effectively rescued the kidney tissue from DOX interceded oxidative damage. Our results suggest that co-treatment of AHE markedly improve DOX-induced deleterious effects in a dose-dependent manner. The potency of AHE co-treatment at 400 mg/kg dose is similar to silymarin. These outcomes revealed that A. hydaspica AHE extract might serve as a potential adjuvant that avoids DOX-induced nephrotoxicity.     

A comparison of the effects of various stimulatory agents on t-PA secretion by normal and malignant cell lines

Succinyl con A and acetyl con A both stimulated epithelial cells to produce similar yields of tissue plasminogen activator (t-PA) to those previously obtained with native con A. However, unlike con A, the derivatized lectins did not adversely affect cell morphology and viability, and cells treated with succinyl con A could secrete t-PA for a prolonged period. Con A and the two derivatives produced similar morphological effects in Bowes melanoma cells, but t-PA production was not increased. Elevated cyclic nucleotide concentrations did not affect t-PA production from epithelial cells, but calcium ionophore treatment generated t-PA yields similar to those obtained with lectins. Azacytidine, which enhanced t-PA production from epithelial cells, did not increase yields from Bowes melanoma cells, and also sodium butyrate, reported to increase t-PA yields from human endothelial cells, had no effect on either cell line.     

Resistance of cultured human fibroblasts and other cells to purine and pyrimidine analogues in relation to mutagenesis detection

In vitro enumeration of diploid human cell variants that are resistant to purine analogues is a possible method of detecting mutagenesis. Their incidences can be increased by the known mutagens, X-rays and N-methyl-N′-nitro-N-nitrosoguanidine (MNNG). Usefulness of this method depends on the kinds of hereditary changes that confer analogue-resistance on somatic cells. If resistance usually results from changes in genetic material, in vitro studies could be useful indicators of mutagenic effects on somatic cells and germ cells in vivo. If epigenetic changes are primarily responsible for analogue-resistant variants, their enumeration might not provide information relevant to germinal mutations but would still be a useful way to detect induction of general kinds of stable phenotypic changes that could cause cancer. This article outlines hypothetical epigenetic and genetic causes of somatic cell variation and a prospective genetic analysis of human cell variants that are resistant to 8-azaguanine (AG) or 2,6-diaminopurine ( (DAP).Recent evidences and arguments favoring epigenetic origins of resistance to base-analogues are inconclusive. The often cited high rate of changes causing impermeability to BUdR in hamster cells is based on one improperly executed determination. Comparisons of rates of variation conferring BUdR-resistance on cultured haploid and diploid frog cells included diploid variants that did not behave as mutants and ignored major sources of error in estimating mutation rates. AG-resistance could result from recessive mutations in X-chromosomal genes but comparisons of rates of mutation in hamster cells of different ploidies did not provide information about the numbers of X-chromosomes in the variants. Reports that normal rodent HGPRT reappeared in hybrids of enzyme-deficient rodent cells and HGPRT-containing cells of other species or in the rodent cells alone in response to the conditions of cell hybridization did not include adequate controls for reversions in mutant genes of the rodent cells. Questions about the epigenetic and genetic origins of analogue-resistance are mostly unanswered. It remains possible that some kinds of abnormal epigenetic changes cause somatic disease. Specific methods for detecting their occurrence and responsiveness to environmental factors should be devised by focusing efforts on traits that are normally subject to epigenetic regulation. Derepression of genes on the inactive X-chromosome and of liver phenylalanine hydroxylase production are presented as possible examples of abnormal epigenetic changes that could be quantitatively studied by direct selection in vitro.     

Mutation at the APRT locus in Friend erythroleukaemia cells 1. Mutation rates and properties of mutants

Spontaneous mutation at the adenine phosphoribosyl transferase (APRT) locus in clone 707 of the Friend cell line was examined. The frequency of cells resistant to 2,6-diaminopurine (DAP) was found to be 2.6 × 10⁻⁵ with a mutation rate of 1.81 × 10⁻⁶ cell⁻¹ generation⁻¹. APRT activities in 9 DAP-resistant clones were found to vary between 0 and 27% the level observed in wild-type cells. It is suggested that clone 707 cells are heterozygous or functionally hemizygous at the APRT locus.     

Evidence for a Functional O-Linked N-Acetylglucosamine (O-GlcNAc) System in the Thermophilic Bacterium Thermobaculum terrenum

Post-translational modification of proteins is a ubiquitous mechanism of signal transduction in all kingdoms of life. One such modification is addition of O-linked N-acetylglucosamine to serine or threonine residues, known as O-GlcNAcylation. This unusual type of glycosylation is thought to be restricted to nucleocytoplasmic proteins of eukaryotes and is mediated by a pair of O-GlcNAc-transferase and O-GlcNAc hydrolase enzymes operating on a large number of substrate proteins. Protein O-GlcNAcylation is responsive to glucose and flux through the hexosamine biosynthetic pathway. Thus, a close relationship is thought to exist between the level of O-GlcNAc proteins within and the general metabolic state of the cell. Although isolated apparent orthologues of these enzymes are present in bacterial genomes, their biological functions remain largely unexplored. It is possible that understanding the function of these proteins will allow development of reductionist models to uncover the principles of O-GlcNAc signaling. Here, we identify orthologues of both O-GlcNAc cycling enzymes in the genome of the thermophilic eubacterium Thermobaculum terrenum. The O-GlcNAcase and O-GlcNAc-transferase are co-expressed and, like their mammalian orthologues, localize to the cytoplasm. The O-GlcNAcase orthologue possesses activity against O-GlcNAc proteins and model substrates. We describe crystal structures of both enzymes, including an O-GlcNAcase·peptide complex, showing conservation of active sites with the human orthologues. Although in vitro activity of the O-GlcNAc-transferase could not be detected, treatment of T. terrenum with an O-GlcNAc-transferase inhibitor led to inhibition of growth. T. terrenum may be the first example of a bacterium possessing a functional O-GlcNAc system.     

Identification of Two Novel Mutations in Adenine Phosphoribosyltransferase Gene in Patients with 2,8‐Dihydroxyadenine Urolithiasis

Five mutations in the adenine phosphoribosyltransferase (APRT) gene have been described in Japanese patients with APRT deficiency. We investigated the APRT gene from three patients with APRT deficiency and two novel mutations, G133D and V84M, were determined.