Chemo-enzymatic synthesis and structure-activity study of artificially N-glycosylated eel calcitonin derivatives with a complex type oligosaccharide

Starting from N-glycosylated eel calcitonin derivatives that contain an N-acetyl-D-glucosamine residue specifically at the 3rd, 14th, 20th or 26th amino acid residue, corresponding glycopeptides with a complex-type oligosaccharide attached to the respective amino acid residue were synthesized by means of a transglycosylation reaction catalyzed by an endo-beta-N-acetylglucosaminidase from Mucor hiemalis . The use of a recombinant enzyme and an excess of a glycosyl donor led to a yield in excess of 60%. Calcitonin derivatives containing truncated oligosaccharides were also prepared via digestion of the complex-type N-glycan with exoglycosidases. Using these N-glycosylated calcitonin derivatives, the effect of carbohydrate structure and glycosylation site on the three-dimensional structure and the biological activity of the peptide were studied. The conformation of the peptide backbone did not change irrespective of the carbohydrate structure or the glycosylation site. However, hypocalcemic activity, calcitonin-receptor binding activity and the biodistribution of the derivatives were affected by the glycosylation and were dependent on both the carbohydrate structure and the glycosylation site. Although the larger oligosaccharides tended to hinder receptor binding, the biodistribution altered by N-glycosylation appeared to enhance the hypocalcemic activity in some cases, and the magnitude of the effect was dependent on the site of glycosylation.     

Role of follicular dendritic cells in the early HIV-1 infection: in vitro model without specific antibody

About 90% of HIV-1 RNA in the lymph nodes is reported to localize in follicular dendritic cellsnetwork (FDC-NW) as early as several days after infection and as much as that in the late stage. But the mechanism remains to be fully understood. To elucidate the role of follicular dendritic cells (FDC) in the early stage of HIV-1 infection, FDC-like cell strains (FDCLC) were established and they were characterized in the co-culture system with T cells for their effect on HIV-1 trapping and replication in p24 immunoassay, immunohistochemistry as well as confocal and electronmicroscopy. Established FDCLC were positive for CNA-42, S-100alpha and intercellular desmosome-like junctions. L-SIGN and DC-SIGN were also detected in FDCLC. Alu-HIV-1 PCR analysis showed no HIV-1 integration in FDCLC. FDCLC trapped HIV-1 and transferred them to uninfected MOLT-4 T cells (MOLT-4) efficiently in the absence of specific antibody. FDCLC also accelerated HIV-1 replication in HIV-1-pre-exposed MOLT-4. These unique FDCLC effects were explained, at least partly, by the fact that FDCLC up-regulated CD4 expression in MOLT-4 and helped T cells escape from apoptosis in the co-culture. These data suggest that FDC/FDCLC engage not only in trapping but also in active expansion of HIV-1 in the absence of specific antibody.     

Catheter-mediated delivery of adenoviral vectors expressing beta-adrenergic receptor kinase C-terminus inhibits intimal hyperplasia and luminal stenosis in rabbit iliac arteries

BACKGROUND: Previous studies have shown that incubation of balloon-injured rat carotid arteries with adenoviral vectors encoding the carboxyl terminus of the beta-adrenergic receptor kinase (Ad2/betaARKct) for 30 min reduces neointima formation. However, it is unclear whether this beneficial effect of betaARKct could be achieved using a catheter-based vector delivery system and whether the observed inhibition of neointima formation translated into a reduction of vessel stenosis. METHODS: In this study, Ad2/betaARKct was infused into the balloon-injured site of rabbit iliac arteries using a porous infusion catheter over 2 min. Twenty-eight days after gene transfer, angiographic and histological assessments were performed. RESULTS: Angiographic and histological assessments indicate significant (p < 0.05) inhibition of iliac artery neointima formation and lumen stenosis by Ad2/betaARKct. Our studies demonstrate that an inhibitory effect of Ad2/betaARKct on neointima formation is achievable using a catheter-based vector delivery system and that the inhibition of neointima formation translates into a gain in the vessel minimal luminal diameter. The extent of inhibition (35%) was comparable to that observed with adenoviral-mediated expression of thymidine kinase plus ganciclovir treatment, a cytotoxic gene therapy approach for restenosis. CONCLUSIONS: These results suggest that adenoviral-mediated gene transfer of betaARKct is a clinically viable cytostatic gene therapy strategy for the treatment of restenosis.     

Chemopreventive effects of hydroxymatairesinol on uterine carcinogenesis in Donryu rats

Hydroxymatairesinol (HMR), obtained from the heartwood of spruce (Picea abies), has been demonstrated to exert chemo-preventive effects on the development of mammary tumors in rats. To examine the influence of HMR on uterine carcinogenesis, adult Donryu rats were initiated with a single intrauterine treatment of N-ethyl-N'-nitro-N-nitrosoguanidine (ENNG) at 11 weeks of age and fed thereafter 0, 200, or 600 ppm HMR mixed in the soy-containing diet until 15 months of age. Incidences of uterine adenocarcinoma in both 200 and 600 ppm HMR-dosed groups were significantly reduced to 11% and 15%, respectively, less than 50% of 0 ppm, at the end of the experiment (P < 0.05). A delay in the start of persistent estrus by HMR was observed at 8 months of age compared with controls given carcinogen alone. From urinalysis, HMR was metabolized mainly to enterolactone and hydroxyenterolactone. These findings suggest that HMR or its metabolites exert chemo-preventive effects in the rat ENNG-uterine carcinogenesis model.     

Ingestion of proanthocyanidins derived from cacao inhibits diabetes-induced cataract formation in rats

Proanthocyanidins derived from cacao (CLP) have various antipathophysiological functions. We have tested whether dietary supplementation with CLP prevents cataract formation in rats with diabetes induced by streptozotocin (STZ), using histological, histochemical, and biochemical analyses. Starting at 7 days after the streptozotocin challenge, the animals were fed either a normal diet or a diet containing 0.5% w/w CLP over 10 weeks. There were no significant differences in plasma and urine glucose concentrations, plasma fructose amines, and plasma thiobarbituric reactive substances (TBARS) between the two dietary groups. Antioxidant status as assessed by measuring lipid peroxide production in plasma in response to azocompounds was lower in the STZ-rats fed control diet than in animals fed CLP. Opacity was first detected in the lenses of the control dietary group 5 weeks after STZ injection and cataracts had developed in the majority of these animals by 10 weeks. These changes were rarely seen in the STZ/CLP diet group. Histological examinations of the eyes of the STZ-treated normal diet group revealed focal hyperplasia of the lens epithelium and liquefaction of cortical fibers. There were similar but considerably less severe changes in the animals fed CLP. Hydroxynonenal (HNE), a marker of oxidative stress, was detected immunohistochemically in the lenses of the STZ-treated normal diet group, but not of those receiving CLP. Our findings suggest that CLP inhibits diabetes-induced cataract formation possibly by virtue of its antioxidative activity.     

Extract of Perilla frutescens enriched for rosmarinic acid, a polyphenolic phytochemical, inhibits seasonal allergic rhinoconjunctivitis in humans

Extract of Perilla frutescens enriched for rosmarinic acid, a polyphenolic phytochemical, suppresses allergic immunoglobulin responses and inflammation caused by polymorphonuclear leukocytes (PMNL) in mice. However, few placebo-controlled clinical trials have examined the efficacy and safety of polyphenolic phytochemicals for treatment of allergic inflammatory diseases in humans. The present study determined whether oral supplementation with rosmarinic acid is an effective intervention for patients with seasonal allergic rhinoconjunctivitis (SAR). In this 21-day, randomized, double-blind, age-matched, placebo-controlled parallel group study, patients with mild SAR were treated daily with extract of Perilla frutescens enriched for rosmarinic acid (200 mg [n=10] or 50 mg [n=9]) or placebo (n=10). Patients recorded symptoms daily in a diary. Profiles of infiltrating cells and concentrations of eotaxin, IL-1beta, IL-8, and histamine were measured in nasal lavage fluid. Serum IgE concentrations and routine blood tests were also examined. As compared with placebo supplementation, supplementation with extract of Perilla frutescens enriched for rosmarinic acid resulted in a significant increase in responder rates for itchy nose, watery eyes, itchy eyes, and total symptoms (P<0.05). Active treatment significantly decreased the numbers of neutrophils and eosinophils in nasal lavage fluid (P<0.05 vs. placebo). Patients reported no adverse events, and no significant abnormalities were detected in routine blood tests. In conclusion, extract of Perilla frutescens enriched for rosmarinic acid can be an effective intervention for mild SAR at least partly through inhibition of PMNL infiltration into the nostrils. Use of this alternative treatment for SAR might reduce treatment costs for allergic diseases.     

Guanylyl cyclase and cGMP-specific phosphodiesterase participate in the acrosome reaction of starfish sperm

In the starfish, Asterias amurensis, the cooperation of three components of the egg jelly, i.e. ARIS (acrosome reaction-inducing substance), Co-ARIS and asterosap, is responsible for inducing the acrosome reaction. Experimentally, ARIS and asterosap are sufficient for the induction. However, when sperm are treated only with asterosap, they become unresponsive to the egg jelly to undergo the reaction. In this study, we analysed the mechanism of the acrosome reaction, using sperm inactivation by asterosap as a clue. Asterosap causes a rapid and transient increase in intracellular cGMP through the activation of the asterosap receptor, a guanylyl cyclase, and causes an increase in intracellular Ca(2+). When sperm were pretreated with asterosap, the guanylyl cyclase seemed to be inactivated irreversibly by dephosphorylation. They were still responsive to ARIS but no longer to asterosap. However, in the presence of IBMX or zaprinast, inhibitors against phosphodiesterases (PDEs), they retained their capacity to undergo the acrosome reaction in response to the egg jelly or ARIS alone. IBMX and zaprinast suppressed the intracellular catabolism of cGMP, but not of cAMP. These results suggest that guanylyl cyclase and cGMP-specific, IBMX- and zaprinast-susceptible PDEs are involved in the regulation of the acrosome reaction.     

The meiotic recombination checkpoint is regulated by checkpoint rad+ genes in fission yeast

During the course of meiotic prophase, intrinsic double-strand breaks (DSBs) must be repaired before the cell can engage in meiotic nuclear division. Here we investigate the mechanism that controls the meiotic progression in Schizosaccharomyces pombe that have accumulated excess meiotic DSBs. A meiotic recombination-defective mutant, meu13Delta, shows a delay in meiotic progression. This delay is dependent on rec12+, namely on DSB formation. Pulsed-field gel electrophoresis analysis revealed that meiotic DSB repair in meu13Delta was retarded. We also found that the delay in entering nuclear division was dependent on the checkpoint rad+, cds1+ and mek1+ (the meiotic paralog of Cds1/Chk2). This implies that these genes are involved in a checkpoint that provides time to repair DSBs. Consistently, the induction of an excess of extrinsic DSBs by ionizing radiation delayed meiotic progression in a rad17(+)-dependent manner. dmc1Delta also shows meiotic delay, however, this delay is independent of rec12+ and checkpoint rad+. We propose that checkpoint monitoring of the status of meiotic DSB repair exists in fission yeast and that defects other than DSB accumulation can cause delays in meiotic progression.     

Affinity selection of DNA-binding proteins from yeast genomic DNA libraries by improved lambda phage display vector

Phage display is a useful means of identifying and selecting proteins of interest that bind specific targets. In order to examine the potential of phage display for the genome-wide screening of DNA-binding proteins, we constructed yeast genomic libraries using lambda foo-based vectors devised in this work. After affinity selection using GAL4 UAS(G) as a probe, phages expressing GAL4 were enriched approximately 5 x 10(5)-fold from the library. Approximately 90% of polypeptides encoded in correct translation reading frames by the selected phages were known or putative polynucleotide-binding proteins. This result clearly indicates that the modified lambda phage display vector in combination with our enrichment technique has great potential for the enrichment of DNA-binding proteins in a sequence-specific manner.     

Development and applications of surface plasmon resonance-based von Willebrand factor-collagen binding assay

Von Willebrand factor (vWf) functions both as a carrier of factor VIII (fVIII) in plasma and as an adhesive protein providing the primary link between collagen of the extracellular matrix and platelets sequestered from blood flow. The functional activity of vWf correlates with the level of its binding to collagen, which is commonly measured in the enzyme-linked immunosorbent assay (ELISA). We developed an automated collagen-binding assay employing the surface plasmon resonance (SPR) phenomenon, which allows one to quantitatively measure the binding of purified vWf and vWf-containing therapeutic fVIII concentrates to collagen type III immobilized on a biosensor chip. The results of the SPR-based assay highly correlated (r = 0.987) with collagen-binding ELISA. The advantages of the SPR-based assay are its higher accuracy and reproducibility in comparison with ELISA. We applied the developed assay for monitoring structural changes in the vWf component of plasma-derived fVIII/vWf concentrates during a virus inactivation procedure performed by heat treatment. We determined the critical residual moisture content of 2% that can be present in lyophilized concentrates during heat-treatment procedures without causing deteriorative changes in vWf properties. Our data suggest that the SPR-based assay is a useful tool in the development of industrial virus-inactivation procedures, allowing one to preserve vWf activity and achieve the maximal therapeutic efficacy of fVIII/vWf concentrates.