Activation characteristics of transient receptor potential ankyrin 1 and its role in nociception

Transient receptor potential (TRP) ankyrin 1 (TRPA1) is a Ca(2+)-permeant, nonselective cationic channel. It is predominantly expressed in the C afferent sensory nerve fibers of trigeminal and dorsal root ganglion neurons and is highly coexpressed with the nociceptive ion channel transient receptor potential vanilloid 1 (TRPV1). Several physical and chemical stimuli have been shown to activate the channel. In this study, we have used electrophysiological techniques and behavioral models to characterize the properties of TRPA1. Whole cell TRPA1 currents induced by brief application of lower concentrations of N-methyl maleimide (NMM) or allyl isothiocyanate (AITC) can be reversed readily by washout, whereas continuous application of higher concentrations of NMM or AITC completely desensitized the currents. The deactivation and desensitization kinetics differed between NMM and AITC. TRPA1 current amplitude increased with repeated application of lower concentrations of AITC, whereas saturating concentrations of AITC induced tachyphylaxis, which was more pronounced in the presence of extracellular Ca(2+). The outward rectification exhibited by native TRPA1-mediated whole cell and single-channel currents was minimal as compared with other TRP channels. TRPA1 currents were negatively modulated by protons and polyamines, both of which activate the heat-sensitive channel, TRPV1. Interestingly, neither protein kinase C nor protein kinase A activation sensitized AITC-induced currents, but each profoundly sensitized capsaicin-induced currents. Current-clamp experiments revealed that AITC produced a slow and sustained depolarization as compared with capsaicin. TRPA1 is also expressed at the central terminals of nociceptors at the caudal spinal trigeminal nucleus. Activation of TRPA1 in this area increases the frequency and amplitude of miniature excitatory or inhibitory postsynaptic currents. In behavioral studies, intraplantar and intrathecal administration of AITC induced more pronounced and prolonged changes in nociceptive behavior than those induced by capsaicin. In conclusion, the characteristics of TRPA1 we have delineated suggest that it might play a unique role in nociception.     

Demonstration of 2',3'-Cyclic Nucleotide 3'-Phosphohydrolase in Cultured Human Schwann Cells

Abstract: Schwann cell cultures were established from adult human sural nerve biopsies. 2'3'-Cyclic nucleotide 3'-phosphohydrolase (CNPase) activity was estimated in the homogenates of those cells by a sensitive isotope assay using [³H]2',3'-cyclic AMP as substrate. A high level of CNPase activity was observed in cultured Schwann cells, whereas cultured human muscle and skin fibroblasts contained negligible levels of CNPase activity. CNPase of human Schwann cells followed typical enzyme-substrate kinetics, with an apparent K _m of 1.6 m M for 2',3'-cyclic AMP, and the enzyme was stimulated by detergents such as Triton X-100 and deoxycholate. It was inhibited by p -chloromercuricbenzoate and 2'-AMP. These properties are typical of CNPase isolated from adult brain and spinal cord. CNPase can serve as a new biochemical marker of normal cultured human Schwann cells and can be useful in analyzing the properties of cultured Schwann cells from patients with dysschwannian neuropathies.     

A combination of two Brugia malayi filarial vaccine candidate antigens (BmALT-2 and BmVAH) enhances immune responses and protection in jirds

In this study filarial recombinant protein or DNA vaccine constructs encoding BmALT-2 and BmVAH as single or as cocktail antigens were evaluated. Male jirds were immunized intramuscularly with DNA vaccine constructs or were immunized intraperitoneally with protein vaccine. The single and bicistronic DNA constructs induced substantial interferon-γ responses in spleen cells; antigen-specific responses were higher following immunization with the bicistronic cocktail construct and evoked a significant protective response of 57% in jirds challenged with Brugia malayi that was similar in the antibody-dependent cellular cytotoxicity (ADCC) assay and micropore chamber experiment. The cocktail protein vaccines induced a mixture of IgG2a (Th1) and IgG1 (Th2) responses with 80% protective response when challenged with B. malayi infective larvae. However, the single protein vaccine rALT-2 induced Th2 (IgG1/IgG3) with a 70% protective response and rVAH induced Th1 (IgG2a) with a lower proliferative response with 60% protection following challenge with B. malayi infective larvae. These results suggest that filarial cocktail protein vaccines are able to elicit substantial immune and protective responses when compared with single antigen vaccination in suitably vaccinated jirds.     

Pancreatic anticancer activity of a novel geranylgeranylated coumarin derivative

A series of hydroxycoumarin derivatives has been synthesized and evaluated against human pancreatic PANC-1 cancer cells under nutrient-deprived conditions. Several compounds exhibited 100% preferential cytotoxicity at low micromolar concentrations under nutrition starvation, and showed no cytotoxicity under nutrient-rich conditions. In this study, a novel geranylgeranylated ether coumarin derivative 9 was found to exhibit the highest cytotoxic activity of 6.25 μM within 24h. The preferential anti-tumor activity exhibited by compound 9 against PANC-1 under low oxygen and nutrient environment illustrates its great potential as a promising lead structure for the development of novel agents to combat pancreatic cancer.     

Fosfomycin Permeation through the Outer Membrane Porin OmpF

Fosfomycin is a frequently prescribed drug in the treatment of acute urinary tract infections. It enters the bacterial cytoplasm and inhibits the biosynthesis of peptidoglycans by targeting the MurA enzyme. Despite extensive pharmacological studies and clinical use, the permeability of fosfomycin across the bacterial outer membrane is largely unexplored. Here, we investigate the fosfomycin permeability across the outer membrane of Gram-negative bacteria by electrophysiology experiments as well as by all-atom molecular dynamics simulations including free-energy and applied-field techniques. Notably, in an electrophysiological zero-current assay as well as in the molecular simulations, we found that fosfomycin can rapidly permeate the abundant Escherichia coli porin OmpF. Furthermore, two triple mutants in the constriction region of the porin have been investigated. The permeation rates through these mutants are slightly lower than that of the wild type but fosfomycin can still permeate. Altogether, this work unravels molecular details of fosfomycin permeation through the outer membrane porin OmpF of E. coli and moreover provides hints for understanding the translocation of phosphonic acid antibiotics through other outer membrane pores.     

Lipase-mediated conversion of vegetable oils into biodiesel using ethyl acetate as acyl acceptor

Ethyl acetate was explored as an acyl acceptor for immobilized lipase-catalyzed preparation of biodiesel from the crude oils of Jatropha curcas (jatropha), Pongamia pinnata (karanj) and Helianthus annuus (sunflower). The optimum reaction conditions for interesterification of the oils with ethyl acetate were 10% of Novozym-435 (immobilized Candida antarctica lipase B) based on oil weight, ethyl acetate to oil molar ratio of 11:1 and the reaction period of 12h at 50 degrees C. The maximum yield of ethyl esters was 91.3%, 90% and 92.7% with crude jatropha, karanj and sunflower oils, respectively under the above optimum conditions. Reusability of the lipase over repeated cycles in interesterification and ethanolysis was also investigated under standard reaction conditions. The relative activity of lipase could be well maintained over twelve repeated cycles with ethyl acetate while it reached to zero by 6th cycle when ethanol was used as an acyl acceptor.     

A simple and efficient procedure for the isolation of high-quality phage lambda DNA using a DEAE-cellulose column

A simple and rapid procedure for purifying large quantities of bacteriophage lambda particles and DNA is described. The procedure involves DEAE-cellulose column chromatography of the phage particles and elution of the phage particles from the column with a low-ionic-strength buffer. The resulting phage were well separated from RNA, DNA, and proteins derived from Escherichia coli host cells. The lambda DNA was prepared from the purified phage particles by the conventional method of phenol extraction and ethanol precipitation. This procedure did not use nucleases, proteases, detergents, or CsCl density gradient centrifugation. The lambda DNA obtained by this method was equivalent in purity to the material prepared by CsCl density gradient centrifugation and amenable to restriction enzyme digestion, ligation, radiolabeling, and double-stranded DNA sequencing. A detailed protocol is described for obtaining 0.5 to 1.0 mg DNA from a 1-liter liquid lysate in less than 5 h. This procedure is simple, inexpensive, and timesaving, and is particularly suitable for large-scale isolation of lambda DNA.