SUMMARY

For the enzymatic production of chitosan oligosaccharides from chitosan, a chitosanase-producing bacterium, Bacillus sp. strain KCTC 0377BP, was isolated from soil. The bacterium constitutively produced chitosanase in a culture medium without chitosan as an inducer. The production of chitosanase was increased from 1.2 U/ml in a minimal chitosan medium to 100 U/ml by optimizing the culture conditions. The chitosanase was purified from a culture supernatant by using CM-Toyopearl column chromatography and a Superose 12HR column for fast-performance liquid chromatography and was characterized according to its enzyme properties. The molecular mass of the enzyme was estimated to be 45 kDa by means of sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The enzyme demonstrated bifunctional chitosanase-glucanase activities, although it showed very low glucanase activity, with less than 3% of the chitosanase activity. Activity of the enzyme increased with an increase of the degrees of deacetylation (DDA) of the chitosan substrate. However, the enzyme still retained 72% of its relative activity toward the 39% DDA of chitosan, compared with the activity of the 94% DDA of chitosan. The enzyme produced chitosan oligosaccharides from chitosan, ranging mainly from chitotriose to chitooctaose. By controlling the reaction time and by monitoring the reaction products with gel filtration high-performance liquid chromatography, chitosan oligosaccharides with a desired oligosaccharide content and composition were obtained. In addition, the enzyme was efficiently used for the production of low-molecular-weight chitosan and highly acetylated chitosan oligosaccharides. A gene (csn45) encoding chitosanase was cloned, sequenced, and compared with other functionally related genes. The deduced amino acid sequence of csn45 was dissimilar to those of the classical chitosanase belonging to glycoside hydrolase family 46 but was similar to glucanases classified with glycoside hydrolase family 8.Chitosan is currently obtained by the deacetylation of chitin (poly-␤-1,4-D-N-acetylglucosamine) that has been extracted from an abundant source of shrimp or crab shells. Deacetylated chitosans are produced by treating chitin in a concentrated alkaline solution (50%, wt/vol) and boiling it for several hours (34). Chitosan is also found in nature; it is found in the cell walls of fungi of the class Zygomycetes, in the chlorophycean algae Chlorella sp. (26), and in insect cuticles (2). These natural chitosans are synthesized by the tandem action of chitin synthetase and chitin deacetylase, as shown for Mucor rouxii and Colletotrichum lindemuthianum (9). Both chemical and enzymatic procedures for chitosan production result in the incomplete deacetylation of chitin, which yields chitosans in the intermediate range of the degree of deacetylation (DDA). Consequently, chitosan can be considered as a partly deacetylated derivative of chitin; it must have diverse structures containing hetero-linkages of N-acetylglucosamine (GlcNAc)-glucosamine (GlcN) and Gl...

Gallic acid, a type of phenolic acid, has been shown to have beneficial effects in inflammation, vascular calcification, and metabolic diseases. The present study was aimed at determining the effect and regulatory mechanism of gallic acid in cardiac hypertrophy and fibrosis. Cardiac hypertrophy was induced by isoproterenol (ISP) in mice and primary neonatal cardiomyocytes. Gallic acid pretreatment attenuated concentric cardiac hypertrophy. It downregulated the expression of atrial natriuretic peptide, brain natriuretic peptide, and beta-myosin heavy chain in vivo and in vitro. Moreover, it prevented interstitial collagen deposition and expression of fibrosis-associated genes. Upregulation of collagen type I by Smad3 overexpression was observed in cardiac myoblast H9c2 cells but not in cardiac fibroblasts. Gallic acid reduced the DNA binding activity of phosphorylated Smad3 in Smad binding sites of collagen type I promoter in rat cardiac fibroblasts. Furthermore, it decreased the ISP-induced phosphorylation of c-Jun N-terminal kinase (JNK) and extracellular signal regulated kinase (ERK) protein in mice. JNK2 overexpression reduced collagen type I and Smad3 expression as well as GATA4 expression in H9c2 cells and cardiac fibroblasts. Gallic acid might be a novel therapeutic agent for the prevention of cardiac hypertrophy and fibrosis by regulating the JNK2 and Smad3 signaling pathway.

Immunohistochemical assays directed at detection of certain combinations of apoptosis proteins may provide prognostic information for patients with early-stage colorectal cancer, and therefore could help to identify patients who might benefit from adjuvant chemotherapy or who should be spared it.

Collagen-derived small peptides, such as Gly-Pro-Hyp (GPH) and Pro-Hyp (PH), play a role in various physiological functions. Although collagen degrades in the gastrointestinal tract randomly and easily, it is not readily cleaved into bioactive peptides. To increase the bioavailability of bioactive peptides, a collagen tripeptide (CTP) was prepared from fish scales by the digestion method using collagenase from nonpathogenic Bacillus bacteria. It was demonstrated that Hyp-containing peptides-GPH and PH-were better absorbed and reached higher plasma levels after the oral administration of CTPs in rats compared to high molecular weight collagen peptide (H-CP). GPH and PH were stable in gastrointestinal fluid and rat plasma for 2 h, and GPH was able to be transported across the intestinal cell monolayer. These results suggest that the ingestion of CTP is an efficient method for taking bioactive peptides orally due to the enzymatic stability and intestinal permeability of GPH and PH.

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Gallic acid (GA) has been reported to have beneficial effects on cancer, vascular calcification, and diabetes-induced myocardial dysfunction. We hypothesized that GA controls hypertension via oxidative stress response regulation in an animal model for essential hypertension. Spontaneously hypertensive rats (SHRs) were administered GA for 16 weeks. GA treatment lowered elevated systolic blood pressure in SHRs through the inhibition of vascular contractility and components of the renin-angiotensin II system. In addition, GA administration reduced aortic wall thickness and body weight in SHRs. In SHRs, GA attenuated left ventricular hypertrophy and reduced the expression of cardiac-specific transcription factors. NADPH oxidase 2 (Nox2) and GATA4 mRNA expression was induced in SHR hearts and angiotensin II-treated H9c2 cells; this expression was downregulated by GA treatment. Nox2 promoter activity was increased by the synergistic action of GATA4 and Nkx2-5. GA seems to regulate oxidative stress by inhibiting the DNA binding activity of GATA4 in the rat Nox2 promoter. GA reduced the GATA4-induced Nox activity in SHRs and angiotensin II-treated H9c2 cells. GA administration reduced the elevation of malondialdehyde levels in heart tissue obtained from SHRs. These findings suggest that GA is a potential therapeutic agent for treating cardiac hypertrophy and oxidative stress in SHRs.

We have studied 215 male patients (aged 45–97 years) whose sole cytogenetic abnormality was clonal loss of the Y chromosome in metaphase cells from unstimulated cultures. The patients comprised a control group with no evidence of hematologic disease and four disease case groups: 1) myelodysplastic syndrome (MDS), refractory anemia, refractory anemia with excess blasts (RAEB), RAEB in transformation, and chronic myelomonocytic leukemia; 2) acute myelogenous leukemia; 3) myeloproliferative disorder (MPD), chronic granulocytic leukemia, and polycythemia vera; and 4) B‐cell lymphoma/leukemia. The frequency of cells with Y loss increased with age and was significantly greater in cases than in controls, but it was not correlated with survival or with prior therapy. The frequency of cases with a ‐Y clone was 6.3% of male karyotypes and represented 16.4% of all abnormal male cytogenetic reports. Much of the difference between cases and controls appears to be accounted for by a greater frequency of cases with > 75% Y loss. A value of 81% chromosome Y loss maximized the combined sensitivity (28%) and specificity (100%) for predicting disease status, but a 75% cutoff provided the best estimate of disease risk. Even in older males, if > 75% of metaphase cells are 45,X,‐Y, they probably represent a disease‐associated clonal population, and it is possible that the critical genetic change is not visible through the microscope. This observation is true for MDS, MPD, B‐cell disease, and especially acute myelogenous leukemia. The prognostic association of Y chromosome loss for survival appears to be neutral or favorable. Genes Chromosomes Cancer 27:11–16, 2000. © 2000 Wiley‐Liss, Inc.