Substrate specificity of mitochondrial intermediate peptidase analysed by a support-bound peptide library.

The substrate specificity of recombinant human mitochondrial intermediate peptidase (hMIP) using a synthetic support-bound FRET peptide library is presented. The collected fluorescent beads, which contained the hydrolysed peptides generated by hMIP, were sequenced by Edman degradation. The results showed that this peptidase presents a remarkable preference for polar uncharged residues at P1 and P1' substrate positions: Ser = Gln > Thr at P1 and Ser > Thr at P1'. Non-polar residues were frequent at the substrate P3, P2, P2' and P3' positions. Analysis of the predicted MIP processing sites in imported mitochondrial matrix proteins shows these cleavages indeed occur between polar uncharged residues. Previous analysis of these processing sites indicated the importance of positions far from the MIP cleavage site, namely the presence of a hydrophobic residue (Phe or Leu) at P8 and a polar uncharged residue (Ser or Thr) at P5. To evaluate this, additional kinetic analyses were carried out, using fluorogenic substrates synthesized based on the processing sites attributed to MIP. The results described here underscore the importance of the P1 and P1' substrate positions for the hydrolytic activity of hMIP. The information presented in this work will help in the design of new substrate-based inhibitors for this peptidase.

Role of anti-oncomirs miR-143 and -145 in human colorectal tumors.

We examined the expression levels of microRNAs (miRNAs (miRs)) in colorectal tumors (63 cancer specimens and 65 adenoma specimens) and paired non-tumorous tissues. Decreased expression of miR-143 and -145 was frequently observed in the adenomas and cancers tested, compared with miR-34a downregulation and miR-21 upregulation. Expression profiles of miR-143 and -145 were not associated with any clinical features. As the downregulation of miR-143 and -145 was observed even in the early phase of adenoma formation, the decreased expression of both miRs would appear to contribute mainly to the initiation step of tumorigenesis, not to the progression stage, and not to clinical prognostic factors. For clinical application, we changed the sequences of the passenger strand in the miR-143 duplex and performed chemical modification at the 3'-overhang portion of miR-143, leading to greater activity and stability to nuclease. The cell growth inhibitory effect of the chemically modified synthetic miR-143 in vitro was greater than that of endogenous miR-143. The miR-143 showed a significant tumor-suppressive effect on xenografted tumors of DLD-1 human colorectal cancer cells. These findings suggest that miR-143 and -145 are important onco-related genes for the initiation step of colorectal tumor development and that the chemically modified synthetic miR-143 may be a hopeful candidate as an RNA medicine for the treatment of colorectal tumors.

Impaired gastric ulcer healing in diabetic mice: role of methylglyoxal.

Methylglyoxal is a reactive dicarbonyl compound produced from cellular glycolytic intermediates that reacts non-enzymatically with proteins to form products such as argpyrimidine at arginine residue. The aim of the present study was to investigate the role of methylglyoxal in the delayed healing of gastric ulcer in diabetes, and to identify the methylglyoxal-modified proteins as a target molecule of this modification. Using male C57BL/6 mice, diabetes was induced by a single i.p. injection of streptozotocin and gastric ulcers were produced by the focal application of 40% of acetic acid to the serosal surface of the stomach. In order to evaluate the effect of OPB-9195, an inhibitor of methylglyoxal modification, on gastric ulcer healing, mice were given orally OPB-9195 (30 mg/kg) twice daily for 14 days, one week before and after the injection of streptozotocin. The area of gastric ulcer on day 7 was significantly increased in diabetic mice compared to non-diabetic mice, indicating delayed ulcer healing. This increase in ulcer area in diabetic mice was significantly reversed by the treatment with OPB-9195 without affecting blood glucose levels. Proteomics analysis showed the methylglyoxal-modification of peroxiredoxin 6 proteins in the diabetic gastric mucosa around gastric ulcer, and this modification was markedly inhibited by the treatment with OPB-9195. In conclusion, the present study suggests a link of increased methylglyoxal modification of proteins including peroxiredoxin 6 to the delayed gastric ulcer healing in diabetes, and also shows the therapeutic potential of the inhibitor of methylglyoxal modification for the treatment of diabetic gastric ulcers.

Inhibition of Bach1 ameliorates indomethacin-induced intestinal injury in mice.

BTB and CNC homolog 1 (Bach1) is a transcriptional repressor of heme oxygenase-1 (HO-1). It plays an important role in the feedback regulation of HO-1 expression, which protects cells from various insults including oxidative stress and inflammatory cytokines. However, the role of Bach1 in intestinal inflammation remains unclear. In this study, the role of Bach1 in intestinal mucosal injury was elucidated using 8-week-old female C57BL/6 (wild-type) and homozygous Bach1-deficient C57BL/6 mice. Intestinal mucosal injuries induced by a single subcutaneous administration of indomethacin were evaluated macroscopically, histologically, and biochemically. Mucosal protein content and chemokine mRNA levels were determined by real-time PCR. Our results showed that the indomethacin-induced intestinal injury was remarkably improved in Bach1-deficient mice. Histological examination showed that the area of injured lesion was decreased in Bach1-deficient mice compared to wild-type mice. Administration of indomethacin induced expression of inflammatory chemokines such as KC, MIP1alpha and MCP1, which was suppressed in Bach1-deficient mice. Myeloperoxidase activity in the intestinal mucosa was also significantly decreased in Bach1-deficient mice. Additionally, Bach1 deficiency enhanced immunopositivity of HO-1 in the intestinal mucosa after indomethacin administration. Disruption of the Bach1 gene thus caused inhibition of mucosal injury, indicating that inhibition of Bach1 may be a novel therapeutic strategy for treating indomethacin-induced intestinal injury.

Influence of the chemical structure of functional monomers on their adhesive performance.

Functional monomers in adhesive systems can improve bonding by enhancing wetting and demineralization, and by chemical bonding to calcium. This study tested the hypothesis that small changes in the chemical structure of functional monomers may improve their bonding effectiveness. Three experimental phosphonate monomers (HAEPA, EAEPA, and MAEPA), with slightly different chemical structures, and 10-MDP (control) were evaluated. Adhesive performance was determined in terms of microtensile bond strength of 4 cements that differed only for the functional monomer. Based on the Adhesion-Decalcification concept, the chemical bonding potential was assessed by atomic absorption spectrophotometry of the dissolution rate of the calcium salt of the functional monomers. High bond strength of the adhesive cement corresponded to low dissolution rate of the calcium salt of the respective functional monomer. The latter is according to the Adhesion-Decalcification concept, suggestive of a high chemical bonding capacity. We conclude that the adhesive performance of an adhesive material depends on the chemical structure of the functional monomer.

Effects of nimesulide, a cyclooxygenase-2 selective inhibitor, on colitis induced tumors.

Cyclooxygenase-2 (COX-2) is known to suppress sporadic colorectal cancer, but effect of selective COX-2 inhibitor in UC-associated neoplasia is still unknown. This study investigated effect of a selective COX-2 inhibitor on colorectal carcinogenesis in experimental murine UC. Chronic colitis was induced in mice by four cycles of administration of dextran sulfate sodium (DSS) (i. e., 5 % DSS for 7 days and distilled water for the following 14 days), and the mice were sacrificed 120 days after the end of the fourth cycle. The mice were divided into the following five groups: Group A, served as a disease control; Group B, received a diet mixed with 400 ppm of nimesulide (NIM), a selective COX-2 inhibitor, during the whole period; Group C, received NIM during the four cycles of DSS administration; Group D, received NIM for 120 days from the end of the fourth cycle; Group E, served as a normal control. In Group D, NIM significantly suppressed the occurrence of dysplasia and/or cancer. The results show that NIM inhibited both dysplasia and cancer in DSS-treated mice, thus showing that NIM has preventive effects on the remission phase of carcinogenesis.

Endoscopic diagnosis of refractory ulcerative colitis.

BACKGROUND & AIM: To make the endoscopic characteristics and clinical appearance of refractory ulcerative colitis (UC) clear, we studied the frequency and location of refractory lesions of severe UC patients. METHODS: The subjects were a total of 68 patients with severe UC. 41 patients were identified with refractory UC, defined as poor response to high-dose systemic steroids (SH-resistant UC), and another group of 27 patients had non-refractory UC (SH-responsive UC). Two groups were compared by the following item; endoscopic findings, locations, effect of treatment, and relation to CMV infection. RESULTS: In SH-resistant UC, longitudinal ulcer and extensive mucosal abrasion were found with high frequency, and there were refractory lesion significantly in proximal colon. In case of UC with refractory lesion, there is a high possibility that treatment is ineffective. Of 14 UC patients with refractory lesion treated with LCAP, 10 obtained remission, whereas only 12 of 30 those patients with treated by only steroids achieved remission. Of 11 steroid-refractory UC patients with CMV detected, were refractory to steroids and had undergone. CONCLUSIONS: The findings of this study suggest that it is very important to decide on a patient's medication by relying on exact diagnosis concerning the condition of UC by endoscopy.

Association of polymorphism of TLR4 and CD14 genes with gastroduodenal diseases in Japan.

BACKGROUND: Host genetic factors may play a key role in determining the long-term outcome of the Helicobacter pylori infection. Toll like receptor 4(TLR4) and CD14-mediated recognition of lipo-polysaccharide (LPS) is required for efficient recognition of Gram-negative bacterial infections. AIMS: We investigated the effects of common polymorphisms of TLR4 Asp299Gly, Thr399Ile and CD14 promoter -C159T on the risk of gastric cancer including its subtypes and clinicopathologic features. We also investigated the effects of these polymorphisms on histologic degree of H. pylori induced gastritis. SUBJECTS: The study was performed in 149 gastric cancer (GC) cases [mean age 64.0 +/- 12.4, M:F = 109:40] and 94 patients without evidence of GC (mean age 64.1 +/- 12.3, M:F = 65:25, Peptic ulcer diseases = 43.6%, gastritis = 56.4%) as the control group. METHODS: TLR4 Asp299Gly, Thr399Ile and CD14 promoter -C159T were determined by PCR-RFLP in all the patients. Gastritis scores of non-cancerous gastric mucosa were assessed according to the updated Sydney system in H. pylori-positive subjects (n = 174). RESULTS: The frequencies of CD14-260 TT and T carrier were significantly lower in patents with intestinal type gastric cancer than in controls (OR = 0.31;95% CI = 0.12-0.78, OR = 0.38; 95% CI = 0.18-0.81, respectively) Compared with patients older than 61 years, the atrophy score in antrum was significantly lower in TT and CT patients. TLR4 Asp299Gly, Thr399Ile were not detected in all the patients. CONCLUSION: Our data suggest that CD14 promoter-159TT and T carrier were associated with lower risk of developing gastric mucosal atrophy in H. pylori infected patients more than 61 years of age, and these genotypes may reduce the risk of intestinal type gastric cancer and TLR4 Asp299Gly, Thr399Ile are very rare in the Japanese population.

Selective granulocyte and monocyte apheresis as a new adjunct to enhance the efficacy of interferon-alpha + ribavirin in patients with high plasma hepatitis C virus.

BACKGROUND AND AIM: Selective granulocyte and monocyte/macrophage adsorptive apheresis is to increase the turnover of infected leucocytes and has increased CD4+ T cells, which are necessary for actions of interferon-alpha on hepatitis C virus. Therefore, granulocyte and monocyte apheresis was to enhance the efficacy of interferon + ribavirin. METHODS: Fifteen patients, 12 had interferon resistant hepatitis C virus and 3 were interferon naive. Hepatitis C virus genotype was 1b in 11 and 2a in 4. The mean plasma HCV-RNA was 728.3 kU/mL and alanine aminotransferase was 107.5 U/L. Granulocyte and monocyte apheresis was with the Adacolumn, which contains carriers that adsorb granulocytes and monocytes/macrophages. After five consecutive granulocyte and monocyte apheresis sessions over 5 days, interferon daily 6 million units for 4 weeks, then three times/week for 20 weeks+ribavirin (600-800 mg per patient per day) were given and followed for another 24 weeks. RESULTS: During granulocyte and monocyte apheresis, plasma HCV-RNA transiently fell by up to 55%. Similarly, incubation of blood with the Adacolumn carriers caused a significant fall in HCV-RNA. Four patients were unavailable for efficacy evaluation. In the other 11, alanine aminotransferase normalised and at 11 weeks, plasma HCV-RNA was negative; six of these (55%) maintained their remission during the follow up. CONCLUSION: Granulocyte and monocyte apheresis appears to deplete extra-hepatic hepatitis C virus reservoirs and generate active complement opsonins, which contribute to hepatitis C virus killing. Additional mechanism(s) are also likely and need to be elucidated in future studies with larger cohort of patients.

Specificity comparison of a serine endopeptidase (SH1) and a serine thiol endopeptidase (STH2) purified from human urine.

In this study, we compared the properties of a serine endopeptidase H1 (SH1) and a serine thiol endopeptidase (STH2) purified from human urine by DEAE-cellulose followed by a Bio Gel A0.5 m or Sepharose Mercurial chromatographs. These enzymes differ in their action upon different hormone peptides. We used fluorogenic substrates to further characterize the enzyme. The substrate specificity of urinary SH1 was studied using different internally quenched fluorescent peptides, and AbzFGQEDDnp was hydrolyzed by SH1. Other enzymes present in urine, such as serine endopeptidase H2, prolyl endopeptidase, neutral endopeptidase like and angiotensin-I converting enzyme, were not able to hydrolyze this substrate. SH1 is 100% inhibited by PMSF and resistant to EDTA, OPA, thiorphan, E64, pOHMB and phosphoramidon. Endopeptidase STH2 is completely inhibited by PMSF, E64 and pOHMB. Enzyme SH1 hydrolyzes the peptide bound F5-S6 at bradykinin (BK: RPPGFSPFR) molecule and R-Q at AbzBKQEDDnp. When studying enzyme STH2, the cleavage sites determined to the related substrates were F5-S6 using BK as substrate and F-R using AbzBKQEDDnp. The kilometers value obtained for AbzBKQEDDnp and AbzFGQEDDnp were 1.18 and 0.007 uM, respectively. Kininases from kidney and urine can hydrolyze peptide bounds from components of the kallikrein-kinin system, the angiotensin-renin system and the neuropeptides system, straight contributing in kidney homeostasis. SH1 was located at the distal tubule [Casarini et al., 1999a, Am. J. Physiol. 277, F66] and can have an important function in the control of kinin found in this portion, since is known that all components of the kallikrein-kinin system were found in this portion. The physiological role of SHT2 could be related to the inter-relation between the kallikrein-kinin system and neuropeptides in the control of the water electrolyte balance [Braz. J. Med. Biol. Res. 25 (3) (1992) 219].

Analysis of pathological risk factors for lymph node metastasis of submucosal invasive colon cancer.

There are currently no universally accepted indications and criteria for additional surgical resection of the colorectum after endoscopic resection of the submucosal invasive cancer. The purpose of the present study is to establish accurate indications and criteria for additional surgical resection of the colorectum, based on the prediction of lymph node metastasis, after endoscopic resection of the submucosal invasive cancer. We investigated 140 submucosal invasive colorectal cancers and analyzed the pathologic factors of lymph node metastasis. The tumors were evaluated for pathologic factors in the invasive area of the submucosal carcinoma and were compared between the cases with lymph node metastasis and those without lymph node metastasis. Lymph node metastasis was observed in 13 cases (9%). Univariate logistic regression analysis showed that the depth of invasion, cribriform-type structural atypia, absence of lymphoid infiltration, lymphatic permeation, and venous permeation were statistically significant as risk factors for lymph node metastasis. Multivariate logistic regression analysis showed that the important risk factors included, in decreasing order, lymphatic permeation, absence of lymphoid infiltration, cribriform-type structural atypia, venous permeation, and depth of invasion. Submucosal invasion of 2 mm or more, and/or, depth of lymphatic permeation of 2 mm or more are risk factors for lymph node metastasis. The pathologic criteria based on our results for additional colectomy enables greater accuracy selection of patients who will undergo further surgical treatment after endoscopic resection.

Characterization of CO3Ap-collagen sponges using X-ray high-resolution microtomography.

For reconstruction and regeneration of hard tissues, scaffold biomaterials with large size pores and high porosity are important, in addition to their roles as supporting frames. To develop a new biodegradable scaffold biomaterial, CO3Ap, which has crystallinity and a chemical composition similar to bone, was synthesized at pH 7.4 and 60 degrees C. Then, the CO3Ap was mixed with a neutralized collagen gel and the CO3Ap-collagen mixtures with different kinds of CO3Ap contents and porosity were lyophilized into sponges. Scanning electron micrography (SEM) observation of CO3Ap-collagen sponges showed favorable pores for cell invasion. Approximately 50-300 microm size pores appeared to continue through the bulk. Higher magnification of the sponge showed a better adhesion between CO3Ap crystals and collagen. X-ray high-resolution microtomography revealed a clear image of the 3D structure of the sponges. The porosity of 0, 70 and 90%(w/w) CO3Ap-collagen sponges was 79.2 +/- 2.8%, 72.6 +/- 2.4% and 48.9 +/- 6.1%, respectively. The 70%(w/w) CO3Ap-collagen sponge appeared to be the most favorable biomaterial from the viewpoint of natural bone properties. Mouse osteoblast MC3T3-E1 cells were cultured in alphaMEM with 10% FCS for 2 weeks. Hematoxylin-eosin staining confirmed osteoblast cells invaded well into the CO3Ap-collagen sponge. These sponges are expected to be used as hard tissue scaffold biomaterials for therapeutic uses.

Overexpression of a DEAD box/RNA helicase protein, rck/p54, in human hepatocytes from patients with hepatitis C virus-related chronic hepatitis and its implication in hepatocellular carcinogenesis.

Hepatitis C virus (HCV) infection is the most common cause of chronic hepatitis, which frequently progresses to hepatocellular carcinoma. The pathogenesis of its persistent infection and tumour progression has not been fully characterized yet. The RCK gene was previously cloned at the breakpoint of the t(11;14)(q23;q32) chromosome translocation observed in human B-cell lymphoma cell line RC-K8. The RCK protein, rck/p54, which is a 54-kDa cytoplasmic protein belonging to the DEAD box/RNA helicase family, is considered to facilitate the translation of mRNA(s) of genes for cell proliferation and malignant transformation not only in B-cell lymphomas having the t(11;14) translocation but also in other solid tumours. The aim of this work was to examine the involvement of rck/p54 in carcinogenesis of hepatocellular carcinoma from HCV-related chronic hepatitis. We examined the expression of rck/p54 in 29 cases of HCV-related chronic hepatitis and eight cases of hepatocellular carcinoma by immunohistochemistry and Western blot analysis. Twenty-six of 29 cases with HCV-related chronic hepatitis and all cases with hepatocellular carcinoma tested overexpressed rck/p54 protein. The expression of rck/p54 was lowered by treatment with IFN-alpha in two cases who showed the decrease in HCV RNA levels. These findings suggest that rck/p54 protein is possibly involved in the replication of HCV genomes in hepatocytes and in tumourigenesis of hepatocellular carcinomas.

Ortho-aminobenzoic acid-labeled bradykinins in interaction with lipid vesicles: fluorescence study.

The peptide hormone bradykinin (BK) (Arg(1)-Pro(2)-Pro(3)-Gly(4)-Phe(5)-Ser(6)-Pro(7)-Phe(8)-Arg(9)) and its shorter homolog BK(1-5) (Arg(1)-Pro(2)-Pro(3)-Gly(4)-Phe(5)) were labeled with the extrinsic fluorescent probe ortho-aminobenzoic acid (Abz) bound to the N-terminal and amidated in the C-terminal carboxyl group (Abz-BK-NH(2) and Abz-BK(1-5)-NH(2)). The fragment des-Arg(9)-BK was synthesized with the Abz fluorescent probe attached to the 3-amino group of 2,3-amino propionic acid (DAP), which positioned the Abz group at the C-terminal side of BK sequence, constituting the peptide des-Arg(9)-BK-DAP(Abz)-NH(2). The spectral characteristics of the probe were similar in the three peptides, and their fluorescent properties were monitored to study the interaction of the peptides with anionic vesicles of dimyristoylphosphatidylglycerol (DMPG). Time-resolved fluorescence experiments showed that the fluorescence decay of the peptides was best described by double-exponential kinetics, with mean lifetimes values around 8.0 ns in buffer pH 7.4 that increased about 10% in the presence of DMPG vesicles. About a 10-fold increase, compared with the values in aqueous solution, was observed in the steady-state anisotropy in the presence of vesicles. A similar increase was also observed for the rotational correlation times obtained from time-resolved anisotropy decay profiles, and related to the overall tumbling of the peptides. Equilibrium binding constants for the peptide-lipid interaction were examined monitoring anisotropy values in titration experiments and the electrostatic effects were evaluated through Gouy-Chapman potential calculations. Without corrections for electrostatic effects, the labeled fragment Abz-BK(1-5)-NH(2) presented the major affinity for DMPG vesicles. Corrections for the changes in peptide concentration due to electrostatic interactions suggested higher affinity of the BK fragments to the hydrophobic phase of the bilayer.

Expression of the EP4 prostaglandin E2 receptor subtype with rat dextran sodium sulphate colitis: colitis suppression by a selective agonist, ONO-AE1-329.

Expression of the EP4 receptor, a prostaglandin (PG)E2 receptor subtype, as well as disease suppression by the administration of a selective EP4 agonist (ONO-AE1-329) was investigated in the colorectal mucosa of rats with dextran sodium sulphate (DSS)-induced colitis. Rats were given drinking water containing 3% DSS for 2 weeks. Expression of EP4 receptor mRNA was barely detectable under normal conditions according to reverse transcription-polymerase chain reaction (RT-PCR). By 1 week after the initial administration of DSS, the receptor mRNA was strongly expressed. After ONO-AE1-329 was administered intracolonically to rats with DSS colitis for 7 consecutive days, erosion and ulceration decreased. Peripheral white blood cell (WBC) counts became less elevated. Interleukin (IL)-1beta and growth-regulated gene product/cytokine-induced neutrophil chemoattractant (GRO/CINC-1) concentrations in colorectal mucosa were lower than in colitis control group (IL-1beta: 12.8 +/- 4.6 and 30.8 +/- 6.2 microg/mg protein, P < 0.05; GRO/CINC-1: 15.5 +/- 3.0 and 39.2 +/- 5.4 microg/mg protein, P < 0.05), and the expression of the corresponding cytokine mRNA was strongly suppressed. IL-10 concentration was higher than in control group (14.5 +/- 1.7 and 7.9 +/- 1.2 microg/mg, P < 0.05), and the mRNA was more strongly expressed. These results suggest that the EP4 receptor is important in colonic inflammation, and that PGE2 suppresses DSS colitis at least partly via the EP4 receptor and the above cytokine changes. Intracolonic administration of selective EP4 agonist might have therapeutic applicability in inflammatory bowel disease such as ulcerative colitis.

Co-overexpression of DEAD box protein rck/p54 and c-myc protein in human colorectal adenomas and the relevance of their expression in cultured cell lines.

The RCK gene was cloned through a study of the breakpoint of the t(11;14)(q23;q32) chromosomal translocation observed in a human B-cell lymphoma and overexpression of the protein (rck/p54) due to the translocation was shown to be associated with malignant transformation. The rck/p54 protein belongs to the DEAD box protein/RNA helicase family, which has a variety of functions such as translation initiation, pre-mRNA splicing and ribosome assembly. It is considered that rck/p54 protein may have significant effects on the mRNA structure of genes associated with cell proliferation, facilitating protein synthesis. Expression of rck/p54 in colorectal adenomas, which are a premalignant lesion of colorectal cancer, was examined by Western blot analysis and immunohistochemistry. The rck/p54 protein was found to be overexpressed in tumor tissues resected from 17 of 26 cases (65.4%) of colorectal adenomas and 13 of 14 c-myc-positive cases (92.8%) also co-overexpressed rck/p54 protein. Thus, a significant correlation between rck/p54 and c-myc co-overexpression was found (Spearman's rank correlation, P = 0.0018). We demonstrate that overexpression of rck/p54 in two different cell lines, COS 7 and human colorectal cancer cell line SW480, caused an increase in c-myc protein levels by enhancement of its translation efficiency and/or stabilization of its mRNA. These results suggest that rck/p54 of the DEAD box protein/RNA helicase family may contribute to cell proliferation and carcinogenesis in the development of human colorectal tumors at the translational level by increasing synthesis of c-myc protein.