Histological and immunohistochemical effects of Curcuma longa on activation of rat hepatic stellate cells after cadmium induced hepatotoxicity

The liver is a target for toxic chemicals such as cadmium (Cd). When the liver is damaged, hepatic stellate cells (HSC) are activated and transformed into myofibroblast-like cells, which are responsible for liver fibrosis. Curcuma longa has been reported to exert a hepato-protective effect under various pathological conditions. We investigated the effects of C. longa administration on HSC activation in response to Cd induced hepatotoxicity. Forty adult male albino rats were divided into: group 1 (control), group 2 (Cd treated), group 3 (C. longa treated) and group 4 (Cd and C. longa treated). After 6 weeks, liver specimens were prepared for light and electron microscopy examination of histological changes and immunohistochemical localization of alpha smooth muscle actin (αSMA) as a specific marker for activated HSC. Activated HSC with a positive αSMA immune reaction were not detected in groups 1 and 3. Large numbers of activated HSC with αSMA immune reactions were observed in group 2 in addition to Cd induced hepatotoxic changes including excess collagen deposition in thickened portal triads, interlobular septa with hepatic lobulation, inflammatory cell infiltration, a significant increase in Kupffer cells and degenerated hepatocytes. In group 4, we observed a significant decrease in HSC that expressed αSMA with amelioration of the hepatotoxic changes. C. longa administration decreased HSC activation and ameliorated hepatotoxic changes caused by Cd in adult rats.     

Phylogenetic relationships of typical antbirds (Thamnophilidae) and test of incongruence based on Bayes factors

Background  

The typical antbirds (Thamnophilidae) form a monophyletic and diverse family of suboscine passerines that inhabit neotropical forests. However, the phylogenetic relationships within this assemblage are poorly understood. Herein, we present a hypothesis of the generic relationships of this group based on Bayesian inference analyses of two nuclear introns and the mitochondrial cytochrome b gene. The level of phylogenetic congruence between the individual genes has been investigated utilizing Bayes factors. We also explore how changes in the substitution models affected the observed incongruence between partitions of our data set.     

A dimeric DNA interface stabilized by stacked A.(G.G.G.G).A hexads and coordinated monovalent cations

We report on the identification of an A.(G.G.G.G).A hexad pairing alignment which involves recognition of the exposed minor groove of opposing guanines within a G.G.G.G tetrad through sheared G.A mismatch formation. This unexpected hexad pairing alignment was identified for the d(G-G-A-G-G-A-G) sequence in 150 mM Na(+) (or K(+)) cation solution where four symmetry-related strands align into a novel dimeric motif. Each symmetric half of the dimeric "hexad" motif is composed of two strands and contains a stacked array of an A.(G.G.G.G).A hexad, a G.G.G.G tetrad, and an A.A mismatch. Each strand in the hexad motif contains two successive turns, that together define an S-shaped double chain reversal fold, which connects the two G-G steps aligned parallel to each other along adjacent edges of the quadruplex. Our studies also establish a novel structural transition for the d(G-G-A-G-G-A-N) sequence, N=T and G, from an "arrowhead" motif stabilized through cross-strand stacking and mismatch formation in 10 mM Na(+) solution (reported previously), to a dimeric hexad motif stabilized by extensive inter-subunit stacking of symmetry-related A.(G.G.G.G).A hexads in 150 mM Na(+) solution. Potential monovalent cation binding sites within the arrowhead and hexad motifs have been probed by a combination of Brownian dynamics and unconstrained molecular dynamics calculations. We could not identify stable monovalent cation-binding sites in the low salt arrowhead motif. By contrast, five electronegative pockets were identified in the moderate salt dimeric hexad motif. Three of these are involved in cation binding sites sandwiched between G.G.G. G tetrad planes and two others, are involved in water-mediated cation binding sites spanning the unoccupied grooves associated with the adjacent stacked A.(G.G.G.G).A hexads. Our demonstration of A.(G. G.G.G).A hexad formation opens opportunities for the design of adenine-rich G-quadruplex-interacting oligomers that could potentially target base edges of stacked G.G.G.G tetrads. Such an approach could complement current efforts to design groove-binding and intercalating ligands that target G-quadruplexes in attempts designed to block the activity of the enzyme telomerase.     

Extracellular metabolism of cyclic AMP.

Intravenously administered cyclic [8-3H]AMP to rats was quickly eliminated from the circulation. After 2 min 93% of the administered radioactivity disappeared from the plasues was recovered mainly in the form of nucleotides, ATP, ADP, AMP and IMP. In vitro contact of cyclic AMP with perfused liver, isolated liver cells and adipose tissue resulted in a rapid breakdown of the nucleotide, presumably on the outer surface of the cells. The degradation products have been identified mainly as adenosine and inosine. Incubation of adipose tissue and isolated liver cells with [3H] AMP also resulted in the breakdown of the nucleotide in themedium. The rate of AMP degradation by these tissues was faster than that for cyclic AMP degradation. The data suggest that cyclic AMP is readily metabolized on the outer surface of cells to products which may be converted within the cells to nucleotides. These findings seem of importance for the quantitative assessments of cellular cyclic AMP outflow during hormonal stimulation.     

Parallel DNA helices. Conformational analysis of regular poly(dG).poly(dC) helices with different variants of base binding]

We have performed a conformational analysis of DNA double helices with parallel directed backbone strands. The calculations were made for homopolymers poly(dG).poly(dC). All possible models of base binding were checked. By the potential energy optimization the dihedral angles and helices parameters of stable conformations of parallel double polynucleotides were calculated. The dependences of conformational energy on the base pair structure were studied. Possible structure of parallel helices with various nucleotide composition are discussed.     

Unusual partially 3-O-methylated alpha-galactan from mushrooms of the genus Pleurotus

Indistinguishable partially 3-O-methylated galactans were isolated from the edible basidiomycetes Pleurotus eryngii and Pleurotus ostreatoroseus. They were obtained via successive aqueous extraction, freeze-thawing, precipitation with Fehling solution of soluble material, and ultrafiltration. Mono- and bidimensional 13C and 1H-nuclear magnetic resonance spectroscopy (HMBC, HETEROTOCSY, COSY, and HMQC), and methylation analysis were used to determine their structures. They were linear, partially 3-O-methylated, (1-->6)-linked alpha-d-galactans containing Gal and 3-Me-Gal, in a 3:1 molar ratio (GC-MS of alditol acetates).     

AMP-activated Protein Kinase (AMPK) Negatively Regulates Nox4-dependent Activation of p53 and Epithelial Cell Apoptosis in Diabetes

Diabetes and high glucose (HG) increase the generation of NADPH oxidase-derived reactive oxygen species and induce apoptosis of glomerular epithelial cells (podocytes). Loss of podocytes contributes to albuminuria, a major risk factor for progression of kidney disease. Here, we show that HG inactivates AMP-activated protein kinase (AMPK), up-regulates Nox4, enhances NADPH oxidase activity, and induces podocyte apoptosis. Activation of AMPK blocked HG-induced expression of Nox4, NADPH oxidase activity, and apoptosis. We also identified the tumor suppressor protein p53 as a mediator of podocyte apoptosis in cells exposed to HG. Inactivation of AMPK by HG up-regulated the expression and phosphorylation of p53, and p53 acted downstream of Nox4. To investigate the mechanism of podocyte apoptosis in vivo, we used OVE26 mice, a model of type 1 diabetes. Glomeruli isolated from these mice showed decreased phosphorylation of AMPK and enhanced expression of Nox4 and p53. Pharmacologic activation of AMPK by 5-aminoimidazole-4-carboxamide-1-riboside in OVE26 mice attenuated Nox4 and p53 expression. Administration of 5-aminoimidazole-4-carboxamide-1-riboside also prevented renal hypertrophy, glomerular basement thickening, foot process effacement, and podocyte loss, resulting in marked reduction in albuminuria. Our results uncover a novel function of AMPK that integrates metabolic input to Nox4 and provide new insight for activation of p53 to induce podocyte apoptosis. The data indicate the potential therapeutic utility of AMPK activators to block Nox4 and reactive oxygen species generation and to reduce urinary albumin excretion in type 1 diabetes.     

Chemical and immunological modifications of an arabinogalactan present in tea preparations of Phyllanthus niruri after treatment with gastric fluid

An arabinogalactan (AG) obtained from tea preparations of Phyllanthus niruri was previously investigated and presented immunological properties when tested with peritoneal mice macrophages. AG was now submitted to acidic and neutral gastric conditions using human gastric fluids and aq. HCl solution. Since the acidic procedures gave rise to the same free monosaccharidic composition, the acid hydrolyzate of AG at pH 2.00 was treated with ethanol to form insoluble (AG-P) and soluble fractions (AG-S). These were analyzed using (13)C NMR, HPSEC, and GC-MS for monosaccharide composition and methylation analyses. The results showed an intense partial degradation, including cleavages of the main chain. AG-S presented the monosaccharides released from the native polymer and some oligosaccharides as shown by methylation data. AG-P contained larger molecular fragments comprising the internal units from AG, which were not attacked by the hydrolysis condition. Both fractions were tested in peritoneal mice macrophages and remained active, promoting an increase of superoxide anion production of 2.0 and 2.3-fold, at 250 microg/mL, for AG-S and AG-P, respectively. When compared to AG, a slight diminished response was observed, revealing a structure-activity relation. The significance of the results is that most plant extracts are orally ingested and will reach the gastrointestinal tract before performing a biological function, so checking these changes is crucial to propose future clinical therapies based on the rational use of phytomedicine.     

Carbohydrate, glycolipid, and lipid components from the photobiont (Scytonema sp.) of the lichen, Dictyomema glabratum

The photobiont of the lichen, Dictyonema glabratum (Scytonema sp.), was isolated and cultivated in a soil-extract medium and submitted to chemical analysis. Successive extractions with CHCl3-MeOH, aqueous MeOH, and H2O gave rise to solutions of lipids (25%), low-molecular-weight carbohydrates (22%), and polysaccharides (4%), respectively. TLC of the lipid extract showed the presence of glycolipids, which were further purified and examined by NMR spectroscopy and GC-MS. Monogalactosyldiacylglycerol (1%), digalactosyldiacylglycerol (0.8%), trigalactosyldiacylglycerol (0.4%), and sulfoquinovosyldiacylglycerol (0.5%) were identified. The most abundant fatty acid ester in each fraction was palmitic (C16:0), but a great variation of the ester composition from one to another was found. Others present were those of C12:0, C14:0, C15:0, C16:1, C17:0, C18:0, C18:1, C18:2, C18:3, C22:0, C22:2, and C24:0. The lipid extract was also subjected to acid methanolysis, which gave rise to dodecane, 2-Me-heptadecane, 2,6-Me2-octadecane, and 8-Me-octadecane, methyl esters of C14:0, C15:0, C16:0, C16:1, C17:0, C18:0, C18:1, C18:2, C20:0, and C24:0 fatty acids, and the dimethyl ester of decanedioic acid. The polysaccharide had mainly Glc, Gal, and Man, with small amounts of 3-O-methylrhamnose and 2-O-methylxylose, both found in plants, and unexpectedly, some of the units were beta-galactofuranose, typical of fungal, but not cyanobacterial polysaccharides. The low-molecular-weight carbohydrates showed mannose as the main free reducing sugar, which differs from Nostoc sp. and Trebouxia sp. photobionts.