Modulation of motor functions involving central dopaminergic system by L-histidine

There exists a possibility of interactions of histaminergic system with other neurotransmitters and their receptors in the central nervous system. Experimental evidences suggest a possible inhibitory influence of histaminergic system on the dopaminergic system. To elucidate the possible interaction between the histaminergic and dopaminergic pathways, we devised a strategy to study their effects on locomotor function and stereotypy behaviour. We investigated the effect of L-histidine, the precursor of histamine, on apomorphine-induced stereotypy and perphenazine-induced catalepsy. Histidine antagonised apomorphine-induced stereotypy. This inhibitory effect of histidine was abolished by both H1- and H2-receptor antagonists, chlorpheniramine and cimetidine, respectively. Perphenazine-induced catalepsy was potentiated by histidine and this effect was inhibited by chlorpheniramine alone but not by cimetidine. These results confirm a possible histamine-dopamine interaction in the modulation of motor functions by the central nervous system.     

Roles of insulin receptor substrate-1, phosphatidylinositol 3-kinase, and release of intracellular Ca2+ stores in insulin-stimulated insulin secretion in beta -cells

The signaling pathway by which insulin stimulates insulin secretion and increases in intracellular free Ca(2+) concentration ([Ca(2+)](i)) in isolated mouse pancreatic beta-cells and clonal beta-cells was investigated. Application of insulin to single beta-cells resulted in increases in [Ca(2+)](i) that were of lower magnitude, slower onset, and longer lifetime than that observed with stimulation with tolbutamide. Furthermore, the increases in [Ca(2+)](i) originated from interior regions of the cell rather than from the plasma membrane as with depolarizing stimuli. The insulin-induced [Ca(2+)](i) changes and insulin secretion at single beta-cells were abolished by treatment with 100 nm wortmannin or 1 micrometer thapsigargin; however, they were unaffected by 10 micrometer U73122, 20 micrometer nifedipine, or removal of Ca(2+) from the medium. Insulin-stimulated insulin secretion was also abolished by treatment with 2 micrometer bisindolylmaleimide I, but [Ca(2+)](i) changes were unaffected. In an insulin receptor substrate-1 gene disrupted beta-cell tumor line, insulin did not evoke either [Ca(2+)](i) changes or insulin secretion. The data suggest that autocrine-activated increases in [Ca(2+)](i) are due to release of intracellular Ca(2+) stores, especially the endoplasmic reticulum, mediated by insulin receptor substrate-1 and phosphatidylinositol 3-kinase. Autocrine activation of insulin secretion is mediated by the increase in [Ca(2+)](i) and activation of protein kinase C.     

Antinociceptive effect of sumatriptan in mice.

Antinociceptive effect of the antimigraine drug sumatriptan (5-HT1A agonist) was studied against acetic acid-induced writhing in mice. Sumatriptan produced the effect in a dose-dependent manner (1, 5, 10 and 20 mg/kg, s.c.). Naloxone (1 mg/kg i.p.) an opiate antagonist failed to reverse sumatriptan-induced antinociception. Cholinomimetic physostigmine (0.05 mg/kg, i.p.) potentiated and the muscarinic antagonist atropine (5 mg/kg, i.p.) blocked the antinociceptive effect of sumatriptan, respectively. The antinociceptive effect of sumatriptan was compared with an another 5-HT agonist (5-HT1A) buspirone which also produced antinociception. Like sumatriptan-analgesia, the buspirone response was also potentiated by physostigmine in atropine sensitive way. Further, buspirone potentiated the analgesic effect of sumatriptan. These observations suggest that 5-HT1A agonists produce antinociception possibly by modulating central cholinergic activity.     

Effects of some curing agents on phenotypic stability in Pseudomonas putida degrading ε-caprolactam

A strain of Pseudomonas putida MCM B-408 capable of utilizing -caprolactam (monomer of nylon-6) as the sole source of carbon and nitrogen was found to harbour a single 32-kb plasmid with the same electrophoretic mobility as that of pARI180, a reference plasmid. Acridine orange, ethidium bromide, mitomycin C and SDS failed to cure the plasmid and the phenotype. Elevated temperature alone (40°C) was found to be ineffective in curing. Phenotype, but not the plasmid, was cured at a frequency of 2.63% when acridine orange and elevated temperature (40°C) were used together. The studies therefore indicated that the phenotypic expression of caprolactam degradative genes is quite stable and that Pseudomonas putida MCM B-408 may degrade -caprolactam from waste-water satisfactorily without spontaneous loss of the property under adverse environmental conditions.     

Micropropagation of licorice (Glycyrrhiza glabra L.) through shoot tip and nodal cultures

Summary Apical and axillary buds ofGlycyrrhiza glabra commonly known as licorice, a plant of repute in the Indian system of medicine, were used for induction of adventitious shoots. For induction of multiple shoots, Murashige and Skoog’s (MS) medium with N⁶-benzyladenine (BA, 0.88–8.87 μM) was used. Reduction in major salts of MS medium enhanced the multiplication ratio up to 1∶10. Plants transferred to the greenhouse showed 90% survival. The present work describes a stepwise protocol for production ofGlycyrrhiza glabra plants on simple minimal media, where very high multiplication rates with healthy root systems were obtained. Roots being the organ of commercial importance, the protocol has tremendous potential.     

Inerolysin, a cholesterol-dependent cytolysin produced by Lactobacillus iners

Lactobacillus iners is a common constituent of the human vaginal microbiota. This species was only recently characterized due to its fastidious growth requirements and has been hypothesized to play a role in the pathogenesis of bacterial vaginosis. Here we present the identification and molecular characterization of a protein toxin produced by L. iners. The L. iners genome encodes an open reading frame with significant primary sequence similarity to intermedilysin (ILY; 69.2% similarity) and vaginolysin (VLY; 68.4% similarity), the cholesterol-dependent cytolysins from Streptococcus intermedius and Gardnerella vaginalis, respectively. Clinical isolates of L. iners produce this protein, inerolysin (INY), during growth in vitro, as assessed by Western analysis. INY is a pore-forming toxin that is activated by reducing agents and inhibited by excess cholesterol. It is active across a pH range of 4.5 to 6.0 but is inactive at pH 7.4. At sublytic concentrations, INY activates p38 mitogen-activated protein kinase and allows entry of fluorescent phalloidin into the cytoplasm of epithelial cells. Unlike VLY and ILY, which are human specific, INY is active against cells from a broad range of species. INY represents a new target for studies directed at understanding the role of L. iners in states of health and disease at the vaginal mucosal surface.     

Modulation of NSAID-induced antinociceptive and anti-inflammatory effects by alpha2-adrenoceptor agonists with gastroprotective effects

Tizanidine, an alpha2-adrenergic receptor agonist with myospasmolytic action, is indicated for the treatment of back pain either as monotherapy or in combination with nonsteridal anti-inflammatory drugs (NSAIDs). Tizanidine (0.25-1.0 mg/kg) significantly produced analgesic and anti-inflammatory effect in acetic acid induced writhing in mice and carrageenan-induced paw edema in rats, respectively. The effects were comparable with clonidine (0.25 and 0.50 mg/kg), another alpha2-agonist. Yohimbine (1 mg/kg), alpha2-adrenergic antagonist reversed the effect of tizanidine. Tizanidine (0.25 mg/kg) and clonidine (0.25 mg/kg) significantly potentiated the antinociceptive and anti-inflammatory effect of NSAIDs (nimesulide, meloxicam and naproxen). Tizanidine (1 mg/kg) did not alter basal pH, acidity (free and total) of gastric content and did not produce any mucosal injury in fasted rats. Tizanidine (1 mg/kg) significantly reduced meloxicam (UD50 3.21 mg/kg), nimesulide (UD50 24.52 mg/kg) and naproxen (UD50 14.10 mg/kg)-induced ulcerogenic effect (ulcer index, pH and free/total acidity). It is expected that tizanidine exerted gastrotprotection through stimulation of gastric and central alpha2-adrenergic receptors. Present investigation suggested that tizanidine not only enhance the analgesic and anti-inflammatory effect of NSAIDs but also improved gatstrointestinal tolerability of NSAIDs through modulation of central alpha-2-receptors. From this study, it can be speculated that tizanidine and NSAID combination therapy would prove to be a novel approach to treat nociceptive/inflammatory conditions with improved gastric tolerability of NSAIDs.     

Surfactant Protein D Inhibits HIV-1 Infection of Target Cells via Interference with gp120-CD4 Interaction and Modulates Pro-Inflammatory Cytokine Production

Surfactant Protein SP-D, a member of the collectin family, is a pattern recognition protein, secreted by mucosal epithelial cells and has an important role in innate immunity against various pathogens. In this study, we confirm that native human SP-D and a recombinant fragment of human SP-D (rhSP-D) bind to gp120 of HIV-1 and significantly inhibit viral replication in vitro in a calcium and dose-dependent manner. We show, for the first time, that SP-D and rhSP-D act as potent inhibitors of HIV-1 entry in to target cells and block the interaction between CD4 and gp120 in a dose-dependent manner. The rhSP-D-mediated inhibition of viral replication was examined using three clinical isolates of HIV-1 and three target cells: Jurkat T cells, U937 monocytic cells and PBMCs. HIV-1 induced cytokine storm in the three target cells was significantly suppressed by rhSP-D. Phosphorylation of key kinases p38, Erk1/2 and AKT, which contribute to HIV-1 induced immune activation, was significantly reduced in vitro in the presence of rhSP-D. Notably, anti-HIV-1 activity of rhSP-D was retained in the presence of biological fluids such as cervico-vaginal lavage and seminal plasma. Our study illustrates the multi-faceted role of human SP-D against HIV-1 and potential of rhSP-D for immunotherapy to inhibit viral entry and immune activation in acute HIV infection.     

Role of anoctamins in cancer and apoptosis

Anoctamin 1 (TMEM16A, Ano1) is a recently identified Ca²⁺-activated chloride channel and a member of a large protein family comprising 10 paralogues. Before Ano1 was identified as a chloride channel protein, it was known as the cancer marker DOG1. DOG1/Ano1 is expressed in gastrointestinal stromal tumours (GIST) and particularly in head and neck squamous cell carcinoma, at very high levels never detected in other tissues. It is now emerging that Ano1 is part of the 11q13 locus, amplified in several types of tumour, where it is thought to augment cell proliferation, cell migration and metastasis. Notably, Ano1 is upregulated through histone deacetylase (HDAC), corresponding to the known role of HDAC in HNSCC. As Ano1 does not enhance proliferation in every cell type, its function is perhaps modulated by cell-specific factors, or by the abundance of other anoctamins. Thus Ano6, by regulating Ca²⁺-induced membrane phospholipid scrambling and annexin V binding, supports cellular apoptosis rather than proliferation. Current findings implicate other cellular functions of anoctamins, apart from their role as Ca²⁺-activated Cl⁻ channels.