Gastroprotective effect of Terminalia arjuna bark on diclofenac sodium induced gastric ulcer

AIM: The present study was aimed to evaluate the effect of methanolic extract of Terminalia arjuna (TA) on diclofenac sodium induced gastric ulcer in experimental rats. METHODS: Animals were induced for gastric ulcer with diclofenac sodium (DIC) (80mg/kg bodyweight in water, orally) and treated orally with TA in various doses ranging from 100mg/kg bodyweight to 500mg/kg bodyweight. The effective dose was 400mg/kg bodyweight, since this dose elicited a maximum reduction in lesion index. The gastroprotective effect of TA was assessed from volume of gastric juice, pH, free and total acidity, pepsin concentration, acid output in gastric juice, the levels of non-protein sulfhydryls (NP-SH), lipid peroxide (LPO), reduced glutathione (GSH), and activities of enzymic antioxidants--super oxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione-S-transferase (GST) and myeloperoxidase (MPO) in gastric mucosa. The levels of DNA, protein bound carbohydrate complexes--hexose, hexoseamine, sialic acid, fucose in gastric mucosa and gastric juice and the levels of RNA in gastric mucosa were assessed. The stomach tissues were used for adherent mucus content and also for the histological examination. RESULTS: A significant reduction in lesion index was observed in ulcer induced animals treated with TA (DIC+TA) compared to ulcerated rats (DIC). A significant increase was observed in pH, NP-SH, GSH, enzymic antioxidants, protein bound carbohydrate complexes, adherent mucus content, nucleic acids with a significant decrease in volume of gastric juice, free and total acidity, pepsin concentration, acid output, LPO levels and MPO activities in DIC+TA rats compared to DIC rats. Histological studies confirmed the gastroprotective activity of TA. CONCLUSION: From the data presented in this study it could be concluded that T. arjuna acts as an gastroprotective agent probably due to its free radical scavenging activity and cytoprotective nature.     

Genetic relatedness and female spatial organization in a solitary carnivore,the raccoon,Procyon lotor

Among mammals, some of the most common types of cohesive social groupings originate from natal philopatry through the extended mother family. This retention of females within social groups (i.e. the nonrandom dispersion of female relatives in space) should affect population genetic structure. We examined the relationship between genetic relatedness and female spatial organization in a wild population of the North-American raccoon, Procyon lotor, a solitary carnivore in east Tennessee. Multilocus genetic band-sharing data and 3(1/2) years of radiotelemetry observations were used to study the spatial and genetic relationships among 38 adult females. DNA amplification employing primers of arbitrary sequence (random amplified polymorphic DNA; RAPD) indicated that female philopatry in raccoons led to a greater likelihood of neighbours being more related than expected by chance. Genetic distance based on RAPD band frequency was positively correlated with spatial distance among females (P = 0.0001) and genetic similarity was positively correlated with the extent of home-range overlap (P = 0.0028). Philopatry seemed biased towards females; average female-female similarities were greater than average male-male similarities (P = 0.0001), or average male-female similarities (P = 0.0001). High home-range overlap among some females with low or moderate levels of band sharing indicated that maternal inheritance of space was not a prerequisite for establishing or sharing home ranges. Female philopatry was the most probable explanation for the nonrandom spatial and genetic association of raccoons in east Tennessee.     

Bacterial periplasmic permeases belong to a family of transport proteins operating from Escherichia coli to human: Traffic ATPases

Bacterial periplasmic transport systems are complex permeases composed of a soluble substrate-binding receptor and a membrane-bound complex containing 2-4 proteins. Recent developments have clearly demonstrated that these permeases are energized by the hydrolysis of ATP. Several in vitro systems have allowed a detailed study of the essential parameters functioning in these permeases. Several of the component proteins have been shown to interact with each other and the actual substrate for the transport process has been shown to be the liganded soluble receptor. The affinity of this substrate for the membrane complex is approximately 10 microM. The involvement of ATP in energy coupling is mediated by one of the proteins in the membrane complex. For each specific permease, this protein is a member of a family of conserved proteins which bind ATP. The similarity between the members of this family is high and extends itself beyond the consensus motifs for ATP binding. Interestingly, over the last few years, several eukaryotic membrane-bound proteins have been discovered which bear a high level of homology to the family of the conserved components of bacterial periplasmic permeases. Most of these proteins are known to, or can be inferred to participate in a transport process, such as in the case of the multidrug resistance protein (MDR), the STE6 gene product of yeast, and possibly the cystic fibrosis protein. This homology suggests a similarity in the mechanism of action and possibly a common evolutionary origin. This exciting development will stimulate progress in both the prokaryotic and eukaryotic areas of research by the use of overlapping procedures and model building. We propose that this universal class of permeases be called 'Traffic ATPases' to distinguish them from other types of transport systems, and to highlight their involvement in the transport of a vast variety of substrates in either direction relative to the cell interior and their use of ATP as energy source.     

ISOLATION,PURIFICATION, AND CHARACTERIZATION OF THERMOPHILIC T80 ISOENZYME OF XYLOSE ISOMERASE FROM THE XEROPHYTE Cereus pterogonus

A thermostable isoenzyme (T₈₀) of xylose isomerase from the eukaryote xerophyte Cereus pterogonus was purified to homogeneity by precipitation with ammonium sulfate and column chromatography on Dowex-1 ion exchange, with Sephadex G-100 gel filtration, resulting in an approximately 25.55-fold increase in specific activity and a final yield of approximately 17.9%. Certain physiochemical and kinetic properties (K_m and V_max) of the T₈₀ xylose isomerase isoenzyme were investigated. The molecular mass of the purified T₈₀ isoenzyme was 68 kD determined by sodium dodecyl sulfate polyacrylamide gel electrophoresis. Polyclonal antibodies against the purified T₈₀ isoenzyme recognized a single polypeptide band on Western blots. The activation energy required for the thermal denaturation of the isoenzyme was determined to be 61.84 KJ mol^?1. The use of differential scanning calorimetry established the melting temperature of the CPXI isoenzyme to be 80°C, but when studied with added metal ions, melting temperature increases to more than the normal. Fluorescence spectroscopy of T₈₀ isoenzymes yielded an emission peak with λ_em at 320 nm and 340 nm, respectively, confirming the presence of Trp residue in these proteins. Electron paramagnetic resonance (EPR) analysis at liquid nitrogen temperature established the presence of Mn²⁺ and Co²⁺ associated with each isoenzyme. These enzyme species exhibited different thermal and pH stabilities compared to their mesophilic counterparts and offered greater efficiency in functioning as a potential alternate catalytic converter of glucose in the production of high-fructose corn syrup (HFCS) for the sweetener industry and for ethanol production.     

Complexes of RecA with LexA and RecX differentiate between active and inactive RecA nucleoprotein filaments

The bacterial RecA protein has been the dominant model system for understanding homologous genetic recombination. Although a crystal structure of RecA was solved ten years ago, we still do not have a detailed understanding of how the helical filament formed by RecA on DNA catalyzes the recognition of homology and the exchange of strands between two DNA molecules. Recent structural and spectroscopic studies have suggested that subunits in the helical filament formed in the RecA crystal are rotated when compared to the active RecA-ATP-DNA filament. We examine RecA-DNA-ATP filaments complexed with LexA and RecX to shed more light on the active RecA filament. The LexA repressor and RecX, an inhibitor of RecA, both bind within the deep helical groove of the RecA filament. Residues on RecA that interact with LexA cannot be explained by the crystal filament, but can be properly positioned in an existing model for the active filament. We show that the strand exchange activity of RecA, which can be inhibited when RecX is present at very low stoichiometry, is due to RecX forming a block across the deep helical groove of the RecA filament, where strand exchange occurs. It has previously been shown that changes in the nucleotide bound to RecA are associated with large motions of RecA's C-terminal domain. Since RecX binds from the C-terminal domain of one subunit to the nucleotide-binding core of another subunit, a stabilization of RecA's C-terminal domain by RecX can likely explain the inhibition of RecA's ATPase activity by RecX.     

Bordetella pertussis extract induces increase in the activities of glycolytic enzymes in mouse liver.

The hypoglycemic effect of Bordetella pertussis (Challenge strain No.18323) purified cell extract (protein with traces of carbohydrates, 2 mg%) administered (0.1 mg/100 g body wt. i.v.) into mice on the activities of the key regulatory enzymes, viz. glucokinase, phosphofructokinase, pyruvate kinase, glyceraldehyde phosphodehydrogenase, glucose-6-phosphate dehydrogenase (G-6-PD) and lactate dehydrogenase, of glycolytic pathway in liver has been studied at varying intervals after injection. The maximum hypoglycaemic effect was observed at the end of 12 hr, while activities of all the enzymes studied showed significant enhancement after 18 hr, thus suggesting increased glucose utilization towards the formation of pyruvate. Actinomycin D is found to inhibit stimulation of G-6-PD activity in B. pertussis treated animals, thereby indicating the role of B. pertussis in synthesis of this enzyme.     

Mullerian inhibiting substance promotes interferon gamma-induced gene expression and apoptosis in breast cancer cells

This report demonstrates that in addition to interferons and cytokines, members of the TGF beta superfamily such as Mullerian inhibiting substance (MIS) and activin A also regulate IRF-1 expression. MIS induced IRF-1 expression in the mammary glands of mice in vivo and in breast cancer cells in vitro and stimulation of IRF-1 by MIS was dependent on activation of the NF kappa B pathway. In the rat mammary gland, IRF-1 expression gradually decreased during pregnancy and lactation but increased at involution. In breast cancer, the IRF-1 protein was absent in 13% of tumors tested compared with matched normal glands. Consistent with its growth suppressive activity, expression of IRF-1 in breast cancer cells induced apoptosis. Treatment of breast cancer cells with MIS and interferon gamma (IFN-gamma) co-stimulated IRF-1 and CEACAM1 expression and synergistic induction of CEACAM1 by a combination of MIS and IFN-gamma was impaired by antisense IRF-1 expression. Furthermore, a combination of IFN-gamma and MIS inhibited the growth of breast cancer cells to a greater extent than either one alone. Both reagents alone significantly decreased the fraction of cells in the S-phase of the cell cycle, an effect not enhanced when they were used in combination. However, MIS promoted IFN-gamma-induced apoptosis demonstrating a functional interaction between these two classes of signaling molecules in regulation of breast cancer cell growth.     

Inverse Agonism of SQ 29,548 and Ramatroban on Thromboxane A2 Receptor

G protein-coupled receptors (GPCRs) show some level of basal activity even in the absence of an agonist, a phenomenon referred to as constitutive activity. Such constitutive activity in GPCRs is known to have important pathophysiological roles in human disease. The thromboxane A2 receptor (TP) is a GPCR that promotes thrombosis in response to binding of the prostanoid, thromboxane A2. TP dysfunction is widely implicated in pathophysiological conditions such as bleeding disorders, hypertension and cardiovascular disease. Recently, we reported the characterization of a few constitutively active mutants (CAMs) in TP, including a genetic variant A160T. Using these CAMs as reporters, we now test the inverse agonist properties of known antagonists of TP, SQ 29,548, Ramatroban, L-670596 and Diclofenac, in HEK293T cells. Interestingly, SQ 29,548 reduced the basal activity of both, WT-TP and the CAMs while Ramatroban was able to reduce the basal activity of only the CAMs. Diclofenac and L-670596 showed no statistically significant reduction in basal activity of WT-TP or CAMs. To investigate the role of these compounds on human platelet function, we tested their effects on human megakaryocyte based system for platelet activation. Both SQ 29,548 and Ramatroban reduced the platelet hyperactivity of the A160T genetic variant. Taken together, our results suggest that SQ 29,548 and Ramatroban are inverse agonists for TP, whereas, L-670596 and Diclofenac are neutral antagonists. Our findings have important therapeutic applications in the treatment of TP mediated pathophysiological conditions.