Effect of Indigofera tinctoria Linn on liver antioxidant defense system during D-galactosamine/endotoxin-induced acute hepatitis in rodents

Effects of pre-treatment with the alcoholic extract of I. tinctoria (500 mg/kg body wt/day, p.o. for 21 days) on liver antioxidant defense system during acute hepatitis induced by D-galactosamine (D-GalN)/endotoxin (LPS extracted by phenol water method from E. coli serotype 0111.B4; 300 mg and 30 micrograms/kg body wt/day, i.p., 18 hr before the assay) were investigated on the activities of enzymic antioxidants such as superoxide dismutase, catalase, glutathione peroxidase and glutathione-s-transferase, and levels of total reduced glutathione in the liver of normal and experimental groups of male albino rats. Since lipid peroxidation and associated membrane damage is a key feature of D-galN/LPS-induced liver injury, the levels of lipid peroxides, was estimated and used as an index of oxidative stress. D-GalN/endotoxin-induced hepatic damage was manifested by a significant decrease in the activities of antioxidant enzymes, decreased glutathione levels and increased levels of lipid peroxides. I. tinctoria pre-treated rats showed considerable protection against D-galN/endotoxin, induced oxidative stress as evidenced by a significant increase in the activities of all the antioxidant enzymes studied and significant decrease in the levels of lipid peroxides. Results indicate that pretreatment with I. tinctoria extract in rats is very effective in reducing D-GalN/endotoxin-induced oxidative stress suggesting an antioxidant effect.     

Dimerization specificity of all 67 B-ZIP motifs in Arabidopsis thaliana: a comparison to Homo sapiens B-ZIP motifs

Basic region-leucine zipper (B-ZIP) proteins are a class of dimeric sequence-specific DNA-binding proteins unique to eukaryotes. We have identified 67 B-ZIP proteins in the Arabidopsis thaliana genome. No A.thaliana B-ZIP domains are homologous with any Homo sapiens B-ZIP domains. Here, we predict the dimerization specificity properties of the 67 B-ZIP proteins in the A.thaliana genome based on three structural properties of the dimeric alpha-helical leucine zipper coiled coil structure: (i) length of the leucine zipper, (ii) placement of asparagine or a charged amino acid in the hydrophobic interface and (iii) presence of interhelical electrostatic interactions. Many A.thaliana B-ZIP leucine zippers are predicted to be eight or more heptads in length, in contrast to the four or five heptads typically found in H.sapiens, a prediction experimentally verified by circular dichroism analysis. Asparagine in the a position of the coiled coil is typically observed in the second heptad in H.sapiens. In A.thaliana, asparagine is abundant in the a position of both the second and fifth heptads. The particular placement of asparagine in the a position helps define 14 families of homodimerizing B-ZIP proteins in A.thaliana, in contrast to the six families found in H.sapiens. The repulsive interhelical electrostatic interactions that are used to specify heterodimerizing B-ZIP proteins in H.sapiens are not present in A.thaliana. Instead, we predict that plant leucine zippers rely on charged amino acids in the a position to drive heterodimerization. It appears that A.thaliana define many families of homodimerizing B-ZIP proteins by having long leucine zippers with asparagine judiciously placed in the a position of different heptads.     

Swim exercise training and adaptations in the antioxidant defense system of myocardium of old rats: relationship to swim intensity and duration

We examined a suitable swim program of different intensities and durations that could evoke changes in the myocardial antioxidant capacity in 22-month-old rats. Male rats (Rattus norvegicus) were assigned to either a sedentary control (SE-C) group or one of six trainee groups. Animals were swim-exercised for 4 weeks with either 20 min or 40 min/day, and three intensities, low, moderate and high. Low-intensity at 20 min/day elicited maximum swim velocity (Sv) and endurance capacity (P<0.05). While serum total cholesterol, triglyceride and low-density lipoprotein (LDL-C) levels were significantly reduced, high-density lipoprotein (HDL-C) showed an increase (P<0.05) in low-intensity trained rats (20 min/day) over SE-C. Notable reduction in blood lactate was also evident. Exercise training significantly increased superoxide dismutase (Mn-SOD), decreased lipid peroxidation products, malondialdehyde and lipofuscin in the left and right ventricles. Increased Mn-SOD with concomitant decrease in lipofuscin in left ventricle was significantly greater than in right ventricle. Moderate- to high-intensity exercise was not effective in either reducing lipid peroxidation products or elevating Mn-SOD activity. These data suggest that swim training at low-intensity of 20 min/day is beneficial as a major protective adaptation against oxidative stress in old myocardium.     

Synthesis and testing of novel classical cannabinoids: exploring the side chain ligand binding pocket of the CB1 and CB2 receptors

A series of C3 cyclic side-chain analogues of classical cannabinoids were synthesized to probe the ligand binding pocket of the CB1 and CB2 receptors. The analogues were evaluated for CB1 and CB2 receptor binding affinities relative to delta(8)-THC. The C3 side-chain geometries of the analogues were studied using high field NMR spectroscopy and quantum mechanical calculations. The results of these studies provide insights into the geometry of the ligand binding pocket of the CB1 and CB2 receptors.     

Clenbuterol induced changes in cholesterol and triglyceride levels of gastrocnemius, pectoralis and heart of rat under work induced stress

Work induced stress led to decreased cholesterol and fluctuating triglyceride levels in gastrocnemius and pectoralis muscles in rats. But the drug (clenbuterol, 2 mg kg(-1) day(-1)) treatment increased cholesterol and triglyceride levels in both the muscles. However, heart showed decreased cholesterol and increased triglyceride level in the animals under work stress, but at the same time drug treatment led to a significant increase in levels of the two lipid fractions, inferring towards deleterious effect of the drug on heart.     

Insulin inhibits PDGF-directed VSMC migration via NO/ cGMP increase of MKP-1 and its inactivation of MAPKs

In this study, we examined the roleof insulin in the control of vascular smooth muscle cell (VSMC)migration in the normal vasculature. Platelet-derived growth factor(PDGF) increased VSMC migration, which was inhibited by pretreatmentwith insulin in a dose-dependent manner. Insulin also caused a 60%decrease in PDGF-stimulated mitogen-activated protein kinase (MAPK)phosphorylation and activation. Insulin inhibition of MAPK wasaccompanied by a rapid induction of MAPK phosphatase (MKP-1), whichinactivates MAPKs by dephosphorylation. Pretreatment with inhibitors ofthe nitric oxide (NO)/cGMP pathway, blocked insulin-induced MKP-1 expression and restored PDGF-stimulated MAPK activation and migration. In contrast, adenoviral infection of VSMCs with MKP-1 or cGMP-dependent protein kinase I (cGK I), the downstream effector of cGMPsignaling, blocked the activation of MAPK and prevented PDGF-directedVSMC migration. Expression of antisense MKP-1 RNA prevented insulin's inhibitory effect and restored PDGF-directed VSMC migration and MAPKphosphorylation. We conclude that insulin inhibition of VSMC migrationmay be mediated in part by NO/cGMP/cGK I induction of MKP-1 andconsequent inactivation of MAPKs.

     

Combined effect of ascorbic acid and selenium supplementation on alcohol-induced oxidative stress in guinea pigs

Oxidative stress is a key step in the pathogenesis of ethanol associated liver injury. Ethanol administration induces an increase in lipid peroxidation either by enhancing the production of oxygen reactive species or by decreasing the level of endogenous antioxidants. In this present study, four groups of male guinea pigs (Cavia porcellus) were maintained for 45 days as follows: Control group (1 mg ascorbic acid (AA)/100 g body wt./day); Ethanol group (1 mg AA/100 g body wt./day+900 mg ethanol/100 g body wt./day); Selenium+AA group (25 mg AA+0.05 mg sodium selenite/100 g body wt./day); Ethanol+Se+AA group (25 mg AA+0.05 mg sodium selenite/100 g body wt.+900 mg ethanol/100 g body wt./day). Malondialehyde (MDA), hydroperoxides (HP) and conjugated dienes (CD) were significantly increased, while the activities of scavenging enzymes superoxide dismutase (SOD) and catalase were reduced in the alcohol administered groups. Co-administration of Se+AA along with alcohol increased the activities of scavenging enzymes and reduced the lipid peroxidation products level in hepatic tissues of guinea pigs. Activities of glutathione peroxidase (GPX) and glutathione reductase (GR) were enhanced in co-administered group. gamma-Glutamyl transpeptidase (GGT), a marker enzyme of alcohol induced toxicity, was also reduced, as was the glutathione content. This study suggests that the combined effect of Se+AA, provides protection against alcohol-induced oxidative stress as evidenced from the decreased levels of lipid peroxidation products and enhanced activities of scavenging enzymes.     

Protocol for in vitro propagation of Excoecaria agallocha L., a medicinally important mangrove species

An in vitro propagation protocol has been developed for Excoecaria agallocha L. (Euphorbiaceae), a mangrove species. Nodal segments were used for axillary shoot proliferation. One shoot from each node of binodal explants was observed 3 weeks after inoculation. The best axillary sprouting was seen on a newly formulated medium containing BA, Zeatin and IBA in concentrations of 13.3 μM, 4.65 μM and 1.23 μM, respectively. The new medium, first used in this study, has a specific composition of major nutrients, MS micronutrients and iron compounds. Nodal segments from rooted cuttings and seedlings responded better than those of mature tree explants. Multiple shoot induction was complemented with efficient shoot elongation, and repeated subculture of binodal segments from axillary shoots resulted in 10–12 shoots per explant in 3 months. Rooting was achieved by growing shoots in the new medium with 0.23 μM IBA. Regenerated plants were successfully acclimatized to the natural environment, and about 85% of plantlets survived under ex vitro conditions. This is the first report of micropropagation in the genus Excoecaria and also in mangrove tree species. Received: 11 August 1997 / Revision received: 10 February 1998 / Accepted: 2 March 1998     

Combination of Adrenomedullin with Its Binding Protein Accelerates Cutaneous Wound Healing

Cutaneous wound continues to cause significant morbidity and mortality in the setting of diseases such as diabetes and cardiovascular diseases. Despite advances in wound care management, there is still an unmet medical need exists for efficient therapy for cutaneous wound. Combined treatment of adrenomedullin (AM) and its binding protein-1 (AMBP-1) is protective in various disease conditions. To examine the effect of the combination treatment of AM and AMBP-1 on cutaneous wound healing, full-thickness 2.0-cm diameter circular excision wounds were surgically created on the dorsum of rats, saline (vehicle) or AM/AMBP-1 (96/320 μg kg BW) was topically applied to the wound daily and wound size measured. At days 3, 7, and 14, skin samples were collected from the wound sites. AM/AMBP-1 treated group had significantly smaller wound surface area than the vehicle group over the 14-day time course. At day 3, AM/AMBP-1 promoted neutrophil infiltration (MPO), increased cytokine levels (IL-6 and TNF-α), angiogenesis (CD31, VEGF and TGFβ-1) and cell proliferation (Ki67). By day 7 and 14, AM/AMBP-1 treatment decreased MPO, followed by a rapid resolution of inflammation characterized by a decrease in cytokines. At the matured stage, AM/AMBP-1 treatment increased the alpha smooth muscle actin expression (mature blood vessels) and Masson-Trichrome staining (collagen deposition) along the granulation area, and increased MMP-9 and decreased MMP-2 mRNA expressions. TGFβ-1 mRNA levels in AM/AMBP-1 group were 5.3 times lower than those in the vehicle group. AM/AMBP-1 accelerated wound healing by promoting angiogenesis, collagen deposition and remodeling. Treatment also shortened the days to reach plateau for wound closure. Thus, AM/AMBP-1 may be further developed as a therapeutic for cutaneous wound healing.