Baicalin reduces the severity of experimental autoimmune encephalomyelitis

Scutellaria baicalensis Georgi is one of the important medicinal herbs widely used for the treatment of various inflammatory diseases in Asia. Baicalin (BA) is a bioactive anti-inflammatory flavone found abundantly in Scutellaria baicalensis Georgi. To explore the therapeutic potential of BA, we examined the effects of systemic administration of the flavone (5 and 10 mg/kg, ip) on relapsing/remitting experimental autoimmune encephalomyelitis (EAE) induced by proteolipid protein 139-151 in SJL/J mice, an experimental model of multiple sclerosis. The mice treated with PBS or BA at day -1 and for 3 consecutive days were observed daily for clinical signs of disease up to 60 days after immunization. In the PBS-EAE group, neurological scores were: incidence (100%), mean day of onset (8.0 +/- 0.73), peak clinical score (3.0 +/- 0.4), and cumulative disease index (141.8 +/- 19.4). In the BA-EAE group (5 or 10 mg kg(-1) day(-1), respectively), incidence (95 or 90%), mean day of onset (9.0 +/- 0.80 or 9.2 +/- 0.75; P = 0.000), peak clinical score (2.2 +/- 0.3 or 2.0 +/- 0.3; P = 0.000), and cumulative disease index (75.9 +/- 10.1 or 62.9 +/- 8.4; P = 0.000) decreased, accompanied by the histopathological findings (decrease of dense mononuclear infiltration surrounding vascellum) for the spinal cord. Additionally, the in vitro effects of BA (5, 10, and 25 microM) on mononuclear cells collected from popliteal and inguinal lymph nodes of day-10 EAE mice were evaluated using an MTT reduction assay for cell proliferation, and ELISA to measure IFN-gamma and IL-4 cytokines. Compared with the control group, BA caused an increase in IL-4 (EAE-DMSO: 3.56 +/- 0.42 pg/mL vs EAE-BA (5, 10, and 25 microM): 6.03 +/- 1.1, 7.83 +/- 0.65, 10.54 +/- 1.13 pg/mL, respectively; P < 0.001); but inhibited IFN-gamma (EAE-DMSO: 485.76 +/- 25.13 pg/mL vs EAE-BA (5, 10, and 25 microM): 87.08 +/- 9.24, 36.27 +/- 5.44, 19.18 +/- 2.93 pg/mL, respectively; P < 0.001) and the proliferation of mononuclear cells (EAE-DMSO: 0.73 +/- 0.021 vs EAE-BA (5, 10, and 25 microM): 0.41 +/- 0.015, 0.31 +/- 0.018, 0.21 +/- 0.11, respectively; P < 0.001) in a concentration-dependent manner. The results suggest that BA might be effective in the treatment of multiple sclerosis.

Evolution of viviparity in warm-climate lizards: an experimental test of the maternal manipulation hypothesis

The maternal manipulation hypothesis for the evolution of reptilian viviparity has been claimed to apply to any situation where gravid females are able to maintain body temperatures different from those available in external nests, but empirical data that support this hypothesis are very limited. Here, we tested this hypothesis using gravid females of a warm-climate lizard, Mabuya multifasciata, by subjecting them to five thermal regimes for the whole gestation period. We found gravid females selected lower body temperatures and thermoregulated more precisely than did nongravid females. Offspring produced in different treatments differed in head size, limb length and sprint speed, but not in overall body size or mass. Variation in morphological traits of offspring was induced primarily by extreme temperatures. Sprint speed of offspring was more likely affected by the mean but not by the variance of gestation temperatures. Gravid females maintained more stable body temperatures than did nongravid females not because these temperatures resulted in the optimization of offspring phenotypes but because the range of temperatures optimal for embryonic development was relatively narrow. Our data conform to the main predictions from the maternal manipulation hypothesis that females should adjust thermoregulation during pregnancy to provide optimal thermal conditions for developing embryos and that phenotypic traits forged by maternal thermoregulation should enhance offspring fitness.

Signalling mechanisms in contraction-mediated stimulation of intracellular NO production in cat ventricular myocytes

In this study we sought to determine whether contractile activity has a role as a signalling mechanism in the activation of intracellular nitric oxide (NO(i)) production induced by electrical stimulation of cat ventricular myocytes. Field stimulation (FS) of single ventricular myocytes elicited frequency-dependent increases in NO(i) that were blocked by the calmodulin (CaM) inhibitor 10 microM W-7 and partially inhibited by the phosphatidylinositol 3'-kinase (PI-(3)K) inhibitor 10 microMm LY294002. Increasing extracellular [Ca(2+)] caused a concentration-dependent increase in FS-induced NO(i) that was partially inhibited by LY294002. The negative inotropic agents BDM (5 mm) or blebbistatin (10 microM) decreased cell shortening and NO(i) production without concomitant changes in L-type Ca(2+) current (I(Ca,L)) or [Ca(2+)](i) transients. The positive inotropic agents EMD 57033 or CGP 48506 (1 microM) increased cell shortening and NO(i) production without concomitant changes in I(Ca,L) or [Ca(2+)](i) transients. FS-induced NO(i) production was decreased in myocytes infected (100 multiplicity of viral infection (MOI); 24 h) with a replication-deficient adenovirus expressing a dominant-negative mutant of protein kinase B (Akt) compared with cells infected with a control adenovirus expressing beta-galactosidase. FS-induced NO(i) was partially inhibited by either endothelial (eNOS) or neuronal nitric oxide synthase (nNOS) inhibitors and completely blocked by simultaneous exposure to both. FS-induced [Ca(2+)](i) transients were increased by the nNOS inhibitor nNOS-I (0.24 microM), decreased by the eNOS inhibitor L-NIO (1 microM) and unchanged by exposure to both inhibitors. We conclude that in cat ventricular myocytes, FS-induced NO(i) production requires both Ca(2+)-dependent CaM signalling and Ca(2+)-independent PI-(3)K-Akt signalling activated by contractile activity. FS activates NO(i) production from both eNOS and nNOS, and each source of NO(i) exerts opposing effects on [Ca(2+)](i) transient amplitude. These findings are important for understanding the regulation of NO(i) signalling in the normal and mechanically failing heart.

Association study between kynurenine 3-monooxygenase gene and schizophrenia in the Japanese population

Several lines of evidence suggest that metabolic changes in the kynurenic acid (KYNA) pathway are related to the etiology of schizophrenia. The inhibitor of kynurenine 3-monooxygenase (KMO) is known to increase KYNA levels, and the KMO gene is located in the chromosome region associated with schizophrenia, 1q42-q44. Single-marker and haplotype analyses for 6-tag single nucleotide polymorphisms (SNPs) of KMO were performed (cases = 465, controls = 440). Significant association of rs2275163 with schizophrenia was observed by single-marker comparisons (P = 0.032) and haplotype analysis including this SNP (P = 0.0049). Significant association of rs2275163 and haplotype was not replicated using a second, independent set of samples (cases = 480, controls = 448) (P = 0.706 and P = 0.689, respectively). These results suggest that the KMO is unlikely to be related to the development of schizophrenia in Japanese.

Adenoviral vector-mediated RTVP-1 gene-modified tumor cell-based vaccine suppresses the development of experimental prostate cancer

We previously identified a novel p53 target gene, RTVP-1, that possesses unique cytotoxic and immunostimulatory activities which make it potentially useful for cancer gene therapy. To test the therapeutic potential of RTVP-1 in a gene-modified tumor cell-based vaccine model, we used an adenoviral vector capable of efficient transduction and expression of RTVP-1 (AdRTVP-1), together with a highly metastatic mouse prostate cancer cell line (178-2 BMA). A vaccine was prepared with 178-2 BMA cells transduced with AdRTVP-1 or a control adenoviral vector expressing beta-galactosidase (Adbetagal). After irradiation of the cells, syngeneic 129/Sv mice were vaccinated three times at weekly intervals. After 3 weeks, they were challenged with orthotopic 178-2 BMA cells. After 21 days, fewer than 60% of the RTVP-1-cell-vaccinated mice developed tumors compared to 100% of the control mice. The RTVP-1-cell vaccine significantly reduced primary tumor wet weight compared with control Adbetagal-cell vaccine (P<0.0001 at 7 and 14 days). Experimental metastasis to lung was also significantly reduced (P=0.0377), and survival significantly increased (P=0.0002). In addition, significantly increased NK and CTL activities were demonstrated in the AdRTVP-1-cell-vaccinated mice. These findings indicate that RTVP-1 gene-modified cell-based vaccines may be useful in the prevention of recurrent prostate cancer.

Phenylephrine acts via IP3-dependent intracellular NO release to stimulate L-type Ca2+ current in cat atrial myocytes

This study determined the effects of alpha1-adrenergic receptor (alpha1-AR) stimulation by phenylephrine (PE) on L-type Ca2+ current (I(Ca,L)) in cat atrial myocytes. PE (10 microm) reversibly increased I(Ca,L) (51.3%; n = 40) and shifted peak I(Ca,L) activation voltage by -10 mV. PE-induced stimulation of I(Ca,L) was blocked by each of 1 microm prazocin, 10 microm L-NIO, 10 microm W-7, 10 microm ODQ, 2 microm H-89 or 10 microm LY294002, and was unaffected by 10 microm chelerythrine or incubating cells in pertussis toxin (PTX). PE-induced stimulation of I(Ca,L) also was inhibited by each of 10 microm ryanodine or 5 microm thapsigargin, by blocking IP3 receptors with 2 microm 2-APB or 10 microm xestospongin C or by intracellular dialysis of heparin. In field-stimulated cells, PE increased intracellular NO (NOi) production. PE-induced NOi release was inhibited by each of 1 microm prazocin, 10 microm L-NIO, 10 microm W-7, 10 microm LY294002, 2 microm H-89, 10 microm ryanodine, 5 microm thapsigargin, 2 microm 2-APB or 10 microm xestospongin C, and unchanged by PTX. PE (10 microm) increased phosphorylation of Akt, which was inhibited by LY294002. Confocal microscopy showed that PE stimulated NOi release from subsarcolemmal sites and this was prevented by 2 mm methyl-beta-cyclodextrin, an agent that disrupts caveolae formation. PE also increased local, subsarcolemmal SR Ca2+ release via IP3-dependent signalling. Electron micrographs of atrial myocytes show peripheral SR cisternae in close proximity to clusters of caveolae. We conclude that in cat atrial myocytes PE acts via alpha1-ARs coupled to PTX-insensitive G-protein to release NOi, which in turn stimulates I(Ca,L). PE-induced NOi release requires stimulation of both PI-3K/Akt and IP3-dependent Ca2+ signalling. NO stimulates I(Ca,L) via cGMP-mediated cAMP-dependent PKA signalling. IP3-dependent Ca2+ signalling may enhance local SR Ca2+ release required to activate Ca2+-dependent eNOS/NOi production from subsarcolemmal caveolae sites.

Presence of plastid and absence of mitochondrial DNA in male reproductive cells as evidence for cytoplasmic inheritance in Turnera ulmifolia and Zantedeschia aethiopica

Epifluorescence microscopy of mature pollen grains of Turnera ulmifolia and Zantedeschia aethiopica stained with 4',6-diamidino-2-phenylindole demonstrated the presence of fluorescent cytoplasmic DNA aggregates in the male reproductive cells of both species. Double staining of the cells with 4',6-diamidino-2-phenylindole and 3,3'-dihexyloxacarbocyanine iodide in Technovit resin sections showed that the mitochondria of these cells did not correspond to the fluorescent cytoplasmic DNA aggregates. Electron microscopy studies revealed both plastids and mitochondria in the cells of these species. In addition, immunoelectron microscopy using an anti-DNA monoclonal antibody showed clear labeling of plastids but not mitochondria. These data provide cytological evidence for biparental plastid inheritance and maternal mitochondrial inheritance in these species.

Impact of antibody framework residue VH-71 on the stability of a humanised anti-MUC1 scFv and derived immunoenzyme

Anti-MUC1 single-chain Fv (scFv) fragments generated from the humanised antibody huHMFG1 had adequate antigen-binding properties but very poor stability irrespective of the applied linker or domain orientation. Mutagenesis of heavy-chain framework residue V_H-71, previously described as a key residue for maintaining the CDR-H2 main-chain conformation and thus important for antigen binding, markedly stabilised the scFv while having only a minor effect on the binding affinity of the molecule. Because of its improved stability, the engineered fragment exhibited immunoreactivity with tumour cells even after 7 days of incubation in human serum at 37°C. It also showed, in contrast to the wild-type scFv, a concentration-dependent binding to the target antigen when displayed on phage. When fusing the scFv to the recombinant ribonuclease rapLRI, only the fusion protein generated with the stable mutant scFv was able to kill MUC1⁺ tumour cells with an IC₅₀ of 80 nM. We expect this novel immunoenzyme to become a promising tool for the treatment of MUC1⁺ malignancies.

The Bcl-2 family pro-apoptotic molecule, BNIP3 regulates activation-induced cell death of effector cytotoxic T lymphocytes

BNIP3 is a recently described pro-apoptotic member of the Bcl-2 family and in BNIP3 cDNA-transfected cell lines, cell death occurs via a caspase-independent pathway with opening of the mitochondrial permeability transition (PT) pore and rapid loss of mitochondrial transmembrane potential (Delta psi m). However, its expression or function in physiologic cell types is not known. Our results using the T-cell receptor transgenic mice P14, specific for lymphocyte choreomeningitis virus (LCMV) glycoprotein, show that in contrast to the other Bcl-2 family pro-apoptotic molecules, BNIP3 is transcriptionally highly up-regulated in effector cytotoxic T lymphocytes (CTL). Because CTL have a propensity to undergo activation-induced cell death (AICD) upon restimulation, we tested for other features associated with BNIP3-induced cell death. AICD of CTL was caspase-independent as determined by measuring caspase activation during target cell killing as well as by lack of inhibition with caspase inhibitors. Moreover, similar to BNIP3-induced cell death, CTL apoptosis was associated with increased production of reactive oxygen species and decreased Delta psi m. Finally, retroviral transduction of BNIP3 antisense RNA diminished AICD in effector CTL. These results suggest that BNIP3 may play an important role in T-cell homeostasis by regulating effector CTL numbers.

Molecular motions and conformational changes of HPPK

6-hydroxymethyl-7,8-dihydropterin pyrophosphokinase (HPPK) belongs to a class of catalytic enzymes involved in phosphoryl transfer and is a new target for the development of novel antimicrobial agents. In the present study, the fundamental consideration is to view the overall structure of HPPK as a network of interacting residues and to extract the most cooperative collective motions that define its global dynamics. A coarse-grained model, harmonically constrained according to HPPK's crystal structure is used. Four crystal structures of HPPK (one apo and three holo forms with different nucleotide and pterin analogs) are studied with the goal of providing insights about the function-dynamic correlation and ligand induced conformational changes. The dynamic differences are examined between HPPK's apo- and holo-forms, because they are involved in the catalytic reaction steps. Our results indicate that the palm-like structure of HPPK is nearly rigid, whereas the two flexible loops: L2 (residues 43-53) and L3 (residues 82-92) exhibit the most concerted motions for ligand recognition and presumably, catalysis. These two flexible loops are involved in the recognition of HPPKs nucleotide and pterin ligands, whereas the rigid palm region is associated with binding of these cognate ligands. Six domains of collective motions are identified, comprised of structurally close but not necessarily sequential residues. Two of these domains correspond to the flexible loops (L2 and L3), whereas the remaining domains correspond to the rigid part of the molecule.

Therapeutic advantage from combining 5-fluorouracil with the hypoxia-selective cytotoxin NLCQ-1 in vivo; comparison with tirapazamine

PURPOSE

The antitumor effect and bone marrow toxicity of 5-fluorouracil (5FU) in combination with the hypoxia-selective cytotoxins NLCQ-1 or tirapazamine (TPZ) were investigated in vivo.

METHODS

Using appropriate intraperitoneal administration schedules for optimal synergistic interactions, the antitumor effect and the bone marrow toxicity of combinations of NLCQ-1 or TPZ and 5FU were determined in EMT6/BALB/c and SCCVII/C3H models in terms of dose modification factors (DMF) using the in vivo-in vitro clonogenic assay as endpoint. Bone marrow toxicity studies were performed in parallel using a modified CFU-GM assay. The antitumor efficacies of each combination treatment under optimal administration conditions were evaluated in the SCCVII/C3H model using also the tumor regrowth assay as endpoint.

RESULTS

A schedule-dependent and tumor-specific synergistic interaction was observed for NLCQ-1 plus 5FU and DMFs of 2.0-2.3 and 1.0 were obtained for the antitumor effect and bone marrow toxicity, respectively, in both tumor models. The antitumor effect of 5FU was slightly potentiated (DMF 1.2) by TPZ in the EMT6/BALB/c model but not in the SCCVII/C3H model when the in vivo-in vitro assay was used as the endpoint. Significant additional tumor regrowth delays (about 11 and 6 days for NLCQ-1 and TPZ, respectively) were observed, compared to the effect of 5FU alone, when an equitoxic dose of NLCQ-1 (10 mg/kg) or TPZ (23 mg/kg) was administered 1 h before 5FU (50 mg/kg) twice a day at 4-h intervals on days 0 and 9.

CONCLUSIONS

These results corroborate the therapeutic advantage of combining hypoxia-selective cytotoxins such as NLCQ-1 and TPZ with chemotherapy.

The humoral immune responses elicited in mice by inoculations with a recombinant protein or DNA based on the circumsporozoite-protein gene of Plasmodium falciparum

The humoral responses elicited in mice by inoculation, in various doses and by several routes, with plasmid DNA containing the gene coding for the circumsporozoite protein (CSP) of Plasmodium falciparum FCC1/HN were compared with those evoked by inoculation with a recombinant expressed protein based on the CSP. With the DNA vaccine, intramuscular inoculations appeared the most effective, followed by intravenous and then subcutaneous injections, the responses in each case being dose-dependent. In both standard ELISA and dot-ELISA, sera from the mice immunized with the DNA were found to have much lower titres of antimalarial antibodies than the corresponding sera from mice immunized with the recombinant protein. Although both 'vaccines' elicited humoral immune responses in BALB/c mice, that based on plasmid DNA took much longer than the recombinant protein to induce high-titre antibody responses.

[Synthesis and biological activity of 2,3-benzopyrone analogs]

Several 2, 3-benzopyrone analogs were synthesized for evaluating their K(+)-channel and anticancer activities. The Friedel-Crafts reaction was taken place with some replacement phenyl acetic acid or its methyl ester and vanillin as reactants in the condition of Ac2O/ZnCl2. All products were confirmed by means of MS and 1H, 13CNMR spectra. Compounds 2 and 3 showed obvious activities on the K(+)-channel and anticancer screening, while the activity of compound 5 was weak. Compound 4 was not yet tested. The primary result indicate that the potential activity of such compounds deserves further study.

Structure and dynamics of 6-hydroxymethyl-7,8-dihydropterin pyrophosphokinase

Folates are essential for life. Unlike mammals, most microorganisms must synthesize folates de novo. 6-Hydroxymethyl-7,8-dihydropterin pyrophosphokinase (HPPK) catalyzes pyrophosphoryl transfer from ATP to 6-hydroxymethyl-7,8-dihydropterin (HP), the first reaction in folate pathway, and therefore, is an ideal target for developing novel antimicrobial agents. Because of its small size and high thermal stability, E. coli HPPK is also an excellent model enzyme for studying the mechanisms of enzymatic pyrophosphoryl transfer. We have determined the crystal structures of HPPK in the unligated form and in complex with HP, two Mg2+ ions, and AMPCPP (an ATP analog that inhibits the enzymatic reaction). Comparison of the two crystal structures reveals dramatic conformational changes of three flexible loops and many side chains and possible roles of the active site residues.

Crystallization and preliminary X-ray diffraction analysis of shikimate kinase from Mycobacterium tuberculosis in complex with MgADP

Shikimate kinase (SK) from Mycobacterium tuberculosis (Mt) was overexpressed in Escherichia coli, purified and cocrystallized with MgADP in hanging drops using the vapor-diffusion procedure with PEG 4000 and 2-propanol as precipitants at pH 7.5. The crystal of MtSK-MgADP, which diffracted to 2.2 A resolution, belonged to space group P3(2)21 or P3(1)21, with unit-cell parameters a = b = 64.01, c = 92.41 A. There was one MtSK molecule in the asymmetric unit. Molecular-replacement trials with the crystal structure of SK from Erwinia chrysanthemi (PDB code 1shk) and adenylate kinase (PDB code 1ake) as search models were not successful. Heavy-atom derivative screening is in progress.

Crystallographic and modeling studies of RNase III suggest a mechanism for double-stranded RNA cleavage

BACKGROUND

Aquifex aeolicus Ribonuclease III (Aa-RNase III) belongs to the family of Mg(2+)-dependent endonucleases that show specificity for double-stranded RNA (dsRNA). RNase III is conserved in all known bacteria and eukaryotes and has 1-2 copies of a 9-residue consensus sequence, known as the RNase III signature motif. The bacterial RNase III proteins are the simplest, consisting of two domains: an N-terminal endonuclease domain, followed by a double-stranded RNA binding domain (dsRBD). The three-dimensional structure of the dsRBD in Escherichia coli RNase III has been elucidated; no structural information is available for the endonuclease domain of any RNase III.

RESULTS

We present the crystal structures of the Aa-RNase III endonuclease domain in its ligand-free form and in complex with Mn(2+). The structures reveal a novel protein fold and suggest a mechanism for dsRNA cleavage. On the basis of structural, genetic, and biological data, we have constructed a hypothetical model of Aa-RNase III in complex with dsRNA and Mg(2+) ion, which provides the first glimpse of RNase III in action.

CONCLUSIONS

The functional Aa-RNase III dimer is formed via mainly hydrophobic interactions, including a "ball-and-socket" junction that ensures accurate alignment of the two monomers. The fold of the polypeptide chain and its dimerization create a valley with two compound active centers at each end of the valley. The valley can accommodate a dsRNA substrate. Mn(2+) binding has significant impact on crystal packing, intermolecular interactions, thermal stability, and the formation of two RNA-cutting sites within each compound active center.