Effect of the carbonic anhydrase inhibitor, acetazolamide, on Helicobacter pylori infection in vivo: a pilot study

BACKGROUND: Carbonic anhydrase inhibitors have been successfully used to treat peptic ulcers. Although carbonic anhydrase restriction does not inhibit Helicobacter pylori in vitro, recent studies suggest that carbonic anhydrase inhibition reduces the ability of H. pylori to survive in an acid environment as present in the stomach. METHODS: In a pilot study, we examined the effect of acetazolamide 500 mg as twice a day for 4 days in volunteers with active H. pylori infection. Effectiveness was judged by changes in the results of the urea breath test. RESULTS: Eight H. pylori infected volunteers completed the test. No urea breath test reverted to negative and there was a trend for the urea breath test value to increase [e.g. delta over baseline (DOB) mean +/- SE increased from 50.9 +/- 13 at baseline to 64.9 +/- 13 at day 5] during treatment with acetazolamide. CONCLUSION: The potential effect of carbonic anhydrase inhibitors on acid secretion may prevent effect on H. pylori in vivo and/or the sites of infection at the surface of the stomach may have a pH higher for any postulated acid-dependent effect to have an effect clinically.     

Expression of alternative oxidase inhibits programmed cell death-like phenomenon in bloodstream form of Trypanosoma brucei rhodesiense

Trypanosoma brucei rhodesiense is one of the causative agents of African Trypanosomiasis. Programmed cell death (PCD) is fundamental in the development, homeostasis and immune mechanisms of multicellular organisms. It has been shown that, other than occurring in multicellular organisms, the PCD phenomenon also takes place in unicellular organisms. In the present study, we have found that under high-density axenic culture conditions, bloodstream form of T. b. rhodesiense depicts a PCD-like phenomenon. We investigated the association of the PCD-like phenomenon with expression of trypanosome alternative oxidase (TAO) under low-temperature stress conditions. We observed that bloodstream form of T. b. rhodesiense did not show any PCD but had up-regulated expression of TAO. Inhibition of TAO by the addition of ascofranone caused the development of PCD in bloodstream T. b. rhodesiense under low-temperature stress, implying that expression of TAO may contribute to the inhibition of PCD.     

Gene knockout analysis of two gamma-tubulin isoforms in mice

Gamma-tubulin regulates the nucleation of microtubules, but knowledge of its functions in vivo is still fragmentary. Here, we report the identification of two closely related gamma-tubulin isoforms, TUBG1 and TUBG2, in mice, and the generation of TUBG1- and TUBG2-deficient mice. TUBG1 was expressed ubiquitously, whereas TUBG2 was primarily detected in the brain. The development of TUBG1-deficient (Tubg1-/-) embryos stopped at the morula/blastocyst stages due to a characteristic mitotic arrest: the mitotic spindle was highly disorganized, and disorganized spindles showed one or two pole-like foci of bundled MTs that were surrounded by condensed chromosomes. TUBG2 was expressed in blastocysts, but could not rescue the TUBG1 deficiency. By contrast, TUBG2-deficient (Tubg2-/-) mice were born, grew, and intercrossed normally. In the brain of wild-type mice, TUBG2 was expressed in approximately the same amount as TUBG1, but no histological abnormalities were found in the Tubg2-/- brain. These findings indicated that TUBG1 and TUBG2 are not functionally equivalent in vivo, that TUBG1 corresponds to conventional gamma-tubulin, and that TUBG2 may have some unidentified function in the brain.     

Expression of MAEG, a novel basement membrane protein, in mouse hair follicle morphogenesis

We screened for genes specifically expressed in the mesenchymes of developing hair follicles using representational differential analysis; one gene identified was MAEG, which encodes a protein consisting of five EGF-like repeats, a linker segment containing a cell-adhesive Arg-Gly-Asp (RGD) motif, and a MAM domain. Immunohistochemistry showed that MAEG protein was localized at the basement membrane of embryonic skin and developing hair follicles, while MAEG expression diminished at the tip of the hair bud. A recombinant MAEG fragment containing the RGD motif was active in mediating adhesion of keratinocytes to the substratum in an RGD-dependent manner. One of the adhesion receptors recognizing the RGD motif was found to be the alpha8beta1 integrin, the expression of which was detected in the placode close to MAEG-positive mesenchymal cells, but later became restricted to the tip of the developing hair bud. Given its localized expression at the basement membrane in developing hair follicles and the RGD-dependent cell-adhesive activity, MAEG may play a role as a mediator regulating epithelial-mesenchymal interaction through binding to RGD-binding integrins including alpha8beta1 during hair follicle development.     

Toxocara canis: search for a potential drug amongst beta-carboline alkaloids--in vitro and mouse studies

The goal of this study was to search for new treatments for Toxocara canis using both in vitro and in vivo experiments. We specifically looked for a treatment for T. canis larva migrans, and examined beta-carboline alkaloids (17 compounds) with various structural modifications, both in in vitro and in vivo experiments. In the in vitro experiments, screening for nematocidal activity on the T. canis second stage larvae, cytotoxic activity, and immune activity in the host were undertaken. Compound 17 was selected, as it exhibited nematocidal activity for T. canis larvae and did not have any cytotoxic or immunosuppressive activity in the host. The effectiveness of compound 17 was then examined using T. canis larvae infected mice in in vivo experiments. To evaluate the anthelmintic effect, the relative mobility value for the larvae was examined in addition to the number of larvae in the brain, skeletal muscle, and liver. Compound 17 was also examined in both free and liposome-entrapped (LE) forms. Polyethylene glycol (PEG)-LE compound 17 showed an anthelmintic effect in which the number of larvae in the brain was decreased compared free albendazole. PEG-LE compound 17 also effectively suppressed the mobility of the larva in brain and skeletal muscle. The experimental procedure employed assisted in the discovery of this potential candidate and is a promising approach for finding alternative therapeutic regimens for T. canis larva migrans.     

Synthetic studies on novel Syk inhibitors. Part 1: Synthesis and structure-activity relationships of pyrimidine-5-carboxamide derivatives

Spleen tyrosine kinase (Syk) is a non-receptor-type tyrosine kinase which mediates diverse responses in haematopoietic cells. Therefore, Syk is an attractive therapeutic target, and in a study of Syk inhibitors as potentially new therapeutic agents, we discovered the 4-anilinopyrimidine-5-carboxamides. Enzyme screening indicated that an aminoethylamino moiety at the 2-position of the pyrimidine ring was important for Syk inhibitory activity, and an investigation of the substituents at the 4-position revealed that an anilino moiety substituted at the meta position was preferred. These compounds showed high selectivity for Syk, compared to other kinases, such as ZAP-70, c-Src, and PKC, and exhibited good inhibitory activities against 5-HT release from RBL-cells. Among them, compound 9a inhibited the passive cutaneous anaphylaxis reaction in mice, with an ID50 of 13 mg/kg following subcutaneous administration. These results suggest that our compounds are worthy of further evaluation as new anti-allergic agents.     

Efficacy of antibodies against a chimeric synthetic peptide encompassing epitopes of bonnet monkey (Macaca radiata) zona pellucida-1 and zona pellucida-3 glycoproteins to inhibit in vitro human sperm-egg binding

Immunocontraception achieved by immunization with zona pellucida (ZP) glycoproteins is invariably associated with ovarian dysfunction. Use of ZP glycoprotein-based synthetic peptides as immunogens has been proposed to overcome adverse side effects on ovaries. In the present study, a chimeric peptide encompassing the epitopes of bonnet monkey (Macaca radiata) ZP glycoprotein-1 (bmZP1; amino acid residues 251-273) and ZP glycoprotein-3 (bmZP3; amino acid residues 324-347), separated by a tri-glycine spacer, was synthesized and conjugated to diphtheria toxoid (DT). Immunization of female BALB/cJ mice and bonnet monkeys with the chimeric peptide led to generation of antibodies that reacted with the chimeric peptide, individual bmZP1 & bmZP3 peptides, and also recombinant bmZP1 and bmZP3 proteins expressed by E. coli in an ELISA. Indirect immunofluorescence studies revealed that the immune serum also recognized human as well as bonnet monkey ZP. A significant inhibition of human sperm binding to ZP was observed with antibodies generated against the chimeric peptide in mice (P = 0.0001) as well as monkeys (P = 0.0002) in a hemizona assay (HZA). The inhibition efficacy was significantly higher than that observed by using antibodies against the individual bmZP1 and bmZP3 peptides. Interestingly, no ovarian pathology was observed in female bonnet monkeys immunized with the chimeric peptide. These studies have demonstrated that the chimeric peptide encompassing peptides of multiple ZP glycoproteins may be a promising candidate antigen for designing immunocontraceptive vaccines.