Yoshiharu Okamoto

Tottori University, TTJ, Tottori, Japan

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Publications (89)184.93 Total impact

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    ABSTRACT: Previous reports indicate that the beneficial effect of chitin nanofibrils (CNFs), and chitosan nanofibrils (CSNFs) for wound healing. In this study, the wound healing effects of superficially deacetylated chitin nanofibrils (SDACNFs) were evaluated using an experimental model. In the experiments using circular excision wound model, SDACNFs induced re-epithelium and proliferation of the fibroblasts and collagen tissue. In the chitin, CNFs, and CSNFs, on the other hand, the e-epithelium and proliferation of the fibroblasts and collagen tissue were not induced perfectly compared with the SDACNFs group. In particular, re-epithelization was observed on day 4 in the only SDACNF group. Moreover, SDACNFs did not induce severe systemic inflammation in the linear incision wound model. The data indicated that SDACNFs effectively induced the proliferation and re-modeling phases compared with chitin, CNFs, and CSNFs in the wound. These data indicate that SDACNFs can be beneficial as a new biomaterial for wound healing. Copyright © 2015 Elsevier Ltd. All rights reserved.
    Carbohydrate Polymers 06/2015; 123:461-467. DOI:10.1016/j.carbpol.2015.02.005 · 3.92 Impact Factor
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    ABSTRACT: Chitin (β-(1-4)-poly-N-acetyl-D-glucosamine) is widely distributed in nature and is the second most abundant polysaccharide after cellulose. It is often converted to its more deacetylated derivative, chitosan. Previously, many reports have indicated the accelerating effects of chitin, chitosan, and its derivatives on wound healing. More recently, chemically modified or nano-fibrous chitin and chitosan have been developed, and their effects on wound healing have been evaluated. In this review, the studies on the wound-healing effects of chitin, chitosan, and its derivatives are summarized. Moreover, the development of adhesive-based chitin and chitosan are also described. The evidence indicates that chitin, chitosan, and its derivatives are beneficial for the wound healing process. More recently, it is also indicate that some nano-based materials from chitin and chitosan are beneficial than chitin and chitosan for wound healing. Clinical applications of nano-based chitin and chitosan are also expected.
    03/2015; 6(1):104-142. DOI:10.3390/jfb6010104
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    ABSTRACT: Previous reports indicate that N-acetyl-d-glucosamine oligomers (chitin oligosaccharide; NACOS) and d-glucosamine oligomers (chitosan oligosaccharide; COS) have various biological activities, especially against cancer and inflammation. In this review, we have summarized the findings of previous investigations that have focused on anticancer or anti-inflammatory properties of NACOS and COS. Moreover, we have introduced recent evaluation of NACOS and COS as functional foods against cancer and inflammatory disease.
    03/2015; 6(1):33-49. DOI:10.3390/jfb6010033
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    ABSTRACT: Novel biological adhesives made from chitin derivatives were prepared and evaluated for their adhesive properties and biocompatibility. Chitin derivatives with acrylic groups, such as 2-hydroxy-3-methacryloyloxypropylated carboxymethyl chitin (HMA-CM-chitin), were synthesized and cured by the addition of an aqueous hydrogen peroxide solution as a radical initiator. The adhesive strength of HMA-CM-chitin increased when it was blended with chitin nanofibers (CNFs) or surface-deacetylated chitin nanofibers (S-DACNFs). HMA-CM-chitin/CNFs or HMA-CM-chitin/S-DACNFs have almost equal adhesive strength compared to that of a commercial cyanoacrylate adhesive. Moreover, quick adhesion and induction of inflammatory cells migration were observed in HMA-CM-chitin/CNF and HMA-CM-chitin/S-DACNF. These findings indicate that the composites prepared in this study are promising materials as new biological adhesives.KeywordsChitin2-Hydroxy-3-methacryloyloxypropylated carboxymethyl chitinAdhesionChitin nanofiber
    Biomaterials 02/2015; 42C. DOI:10.1016/j.biomaterials.2014.11.043 · 8.31 Impact Factor
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    ABSTRACT: Export Date: 18 October 2014
    Carbohydrate Polymers 01/2015; 115:448-456. DOI:10.1016/j.carbpol.2014.09.012 · 3.92 Impact Factor
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    ABSTRACT: Canine oral malignant melanoma (COMM) is the most aggressive malignant tumor in dogs. Lupeol is a triterpene extracted from various fruits and vegetables that reportedly inhibits melanoma cell proliferation in vitro and in vivo. In this study, the efficacy of subcutaneous lupeol for spontaneous COMM was evaluated. A total of 11 dogs (3, 5 and 3 dogs diagnosed with clinical stage I, II and III melanoma, respectively) were evaluated. Subcutaneous lupeol (10 mg/kg) was administered postoperatively at various time points to treat these 11 COMM cases. Of the 11 subjects, 7 exhibited no local recurrence 180 days postoperatively and no severe adverse effects were observed in any of the cases. Furthermore, no distant metastasis was observed during the experimental period. Therefore, systemic lupeol may prevent local tumor progression and distant metastasis and may be a novel adjuvant treatment for the treatment of COMM.
    Molecular and Clinical Oncology 01/2015; 3(1):89-92. DOI:10.3892/mco.2014.450
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    ABSTRACT: High temperature hyperthermia (HTH) treatment has previously been demonstrated to suppress tumor growth in a tumor-bearing rat model. In the present study, the effects of HTH therapy for the treatment of spontaneous tumors in canines was evaluated. In case 1, an 18-year-old female Papillon presented with a right forelimb rhabdomyosarcoma. Case 2 was a 13-year-old male English Cocker Spaniel with a right external auditory canal ceruminous adenocarcinoma and case 3 was a 14-year-old male Golden Retriever that exhibited a perianal gland adenocarcinoma, which surrounded the anus. HTH treatment was performed in all three cases for 10 min at 45-65°C with or without the inhalation of isoflurane. In case 1, the tumor disappeared four weeks following HTH treatment. In case 2, the tumor volume had decreased by day 21, and in case 3, HTH was performed three times and the tumor disappeared following the third procedure. HTH is considered to be a simple procedure with no severe side effects. Consequently, this treatment modality is hypothesized to become a useful alternative therapy for superficial tumors in companion animals.
    Oncology letters 11/2014; 8(5):2055-2058. DOI:10.3892/ol.2014.2496 · 0.99 Impact Factor
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    ABSTRACT: The aim of this study was to understand the effects of fish scale collagen peptide (SC) on an experimental ulcerative colitis (UC) mouse model. SC shortened colon length, increased colon weight/length ratio, and ameliorated histological tissue injury in dextran sulfate sodium (DSS)-induced acute UC mice. SC suppressed inflammation in acute UC by decreasing myeloperoxidase-dependent activation of inflammatory cells such as leukocytes. SC suppressed the activation of nuclear factor–kappa B (NF-κB) in colon and serum monocyte chemotactic protein-1 in the DSS-induced acute UC mouse model. Gelatin, on the other hand, did not suppress clinical symptoms, colon inflammation, and colon fibrosis in DSS-induced acute UC. These results revealed that SC has anti-inflammatory effects in the DSS-induced acute UC model. Our results indicate that SC could be a new functional food for patients with inflammatory bowel disease.
    10/2014; DOI:10.1016/j.phanu.2014.10.001
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    ABSTRACT: The current study evaluated the anti-tumor activities of N-acetyl-d-glucosamine oligomer (NACOS) and glucosamine oligomer (COS) after their oral administration in a tumor (colon 26)-bearing mouse model. Compared to the control group, NACOS and COS groups showed significantly suppressed tumor growth, and apparent, marked apoptosis in tumor tissues. Furthermore, serum interleukin-12p70 and interferon-γ levels significantly increased in the NACOS and COS groups compared to the corresponding levels in the control group. Collectively, the results indicate the oral administration of NACOS and COS could enhance innate immunity. Results of experiments in Myd-88 knockout mice revealed that the apparent effects were related to both Myd-88-dependent and Myd-88-independent pathways. The data indicated that oral administration of NACOS and COS produced anti-tumor effects through the induction of apoptosis and stimulation of the immune system, which suggests that NACOS and COS are candidate anti-tumor functional foods.
    Carbohydrate Polymers 10/2014; 111C:783-787. DOI:10.1016/j.carbpol.2014.04.102 · 3.92 Impact Factor
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    ABSTRACT: Chitin (β-(1-4)-poly-N-acetyl-D-glucosamine) is widely distributed in nature and is the second most abundant polysaccharide after cellulose. Chitin occurs in nature as ordered macrofibrils. It is the major structural component in the exoskeleton of crab and shrimp shells and the cell wall of fungi and yeast. As chitin is not readily dissolved in common solvents, it is often converted to its more deacetylated derivative, chitosan. Chitin, chitosan, and its derivatives are widely used in tissue engineering, wound healing, and as functional foods. Recently, easy methods for the preparation of chitin and chitosan nanofibers have been developed, and studies on biomedical applications of chitin and chitosan nanofibers are ongoing. Chitin and chitosan nanofibers are considered to have great potential for various biomedical applications, because they have several useful properties such as high specific surface area and high porosity. This review summarizes methods for the preparation of chitin and chitosan nanofibers. Further, biomedical applications of chitin and chitosan nanofibers in (i) tissue engineering, (ii) wound dressing, (iii) cosmetic and skin health, (iv) stem cell technology, (v) anti-cancer treatments and drug delivery, (vi) anti-inflammatory treatments, and (vii) obesity treatment are summarized. Many studies indicate that chitin and chitosan nanofibers are suitable materials for various biomedical applications.
    Journal of Biomedical Nanotechnology 10/2014; 10(10):2891-2920. DOI:10.1166/jbn.2014.1882 · 7.58 Impact Factor
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    ABSTRACT: Previous studies have suggested that ozonated water is safe and possesses antibacterial effects for treatment of experimental peritonitis rats. In this study, we evaluated the anti-inflammatory effects of ozonated water that was intraperitoneally injected into an experimental inflammatory mouse model. The concentrations of dissolved ozone decreased constantly and lineally, while the half-life of dissolved ozone was 36.8±2.7 min (27°C). The 10-ppm ozonated water was injected intraperitoneally into mice with lipopolysaccharide (LPS)-induced acute inflammation. The results showed that the intraperitoneal injection of ozonated water decreased the levels of tumor necrosis factor-α (TNF-α) and increased the activity of superoxide dismutase (SOD). The results suggest that ozonated water has anti-inflammatory properties and is a potential therapeutic option for acute inflammation.
    09/2014; 2(5):671-674. DOI:10.3892/br.2014.290
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    ABSTRACT: Cryoablation is a minimally invasive cancer treatment. In this study, the effects of cryoablation on normal rabbit bone were evaluated using imaging and histopathological examinations. Cryoablation was performed using a Cryo-Hit (Galil Medical, Yokneam, Israel). Under anesthesia, one cryoablation needle was inserted at the center of the femur (day 0). To create an ice ball (2 × 3 cm), two 10-min freeze cycles were performed, separated by a 5-min thaw cycle. During cryoablation, changes in the bone and regional tissue were monitored using magnetic resonance imaging (MRI). MRI scans, computed tomography (CT) scans, and collections from the femur (for histopathological evaluation) were performed on days 7, 14, 28, and 56. In terms of the all rabbits' general conditions, we did not observe lameness, decreased appetite, or any other side effects during the experimental periods. Histopathological evaluations of the femur were performed using hematoxylin and eosin staining. MRI indicated inflammation around the ice ball on day 7. Subsequently, the area of inflammation gradually decreased from days 14 to 56. In the histopathological examination, necrosis of bone marrow cells and endosteum were observed from days 7 to 56. No regeneration of bone marrow cells was observed during the experimental period. On the other hand, cryoablation did not influence osteoblasts. Furthermore, there was no pathologic fracture during the experimental period. Our results suggest that cryoablation does not induce severe adverse effects on normal bone, and therefore has potential as a therapeutic option for bone tumors, including metastatic tumors to bone.
    Cryobiology 07/2014; 69(2). DOI:10.1016/j.cryobiol.2014.07.010 · 1.64 Impact Factor
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    ABSTRACT: This report describes a dog with a clinical stage III oral malignant melanoma that was treated with complementary alternative medicine (CAM). The CAM included high temperature hyperthermia, dendritic cell therapy and lupeol injections. Surgery, radiation and chemotherapy were not performed. Two months after the start of treatment, the tumor disappeared and after six months, the follow-up examinations revealed no recurrence or metastasis of the tumor. Quality of life (QOL) of the dog was maintained; therefore, the application of CAM may be an effective treatment for canine oral malignant melanoma. The effective application of CAM has the potential to prolong life and maintain an excellent QOL for pets.
    Oncology letters 06/2014; 7(6):1829-1830. DOI:10.3892/ol.2014.2041 · 0.99 Impact Factor
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    ABSTRACT: The present study examined the effects of onion peel tea (OPT) in a mouse model of high-fat-diet-induced obesity. BALB/c mice were fed a high-fat diet for three weeks, followed by a normal diet with or without OPT for 28 days. OPT suppressed the increases in body weight and level of epididymal fat tissue; it also significantly reduced the serum concentrations of total cholesterol on day 14 and those of glucose and leptin on day 28. The results indicate that OPT has anti-obesity effects in an experimental mouse model of high-fat-diet-induced obesity.
    Experimental and therapeutic medicine 02/2014; 7(2):379-382. DOI:10.3892/etm.2013.1433 · 0.94 Impact Factor
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    ABSTRACT: Chitins are highly crystalline structures that are predominantly found in crustacean shells. Alpha-chitin is composed of microfibers, which are made up of nanofibrils that are 2-5nm in diameter and 30nm in length and embedded in a protein matrix. Crystalline nanofibrils can also be prepared by acid treatment. We verified the effect of chitin nanofibrils (NF) and nanocrystals (NC) on skin using a three-dimensional skin culture model and Franz cells. The application of NF and NC to skin improved the epithelial granular layer and increased granular density. Furthermore, NF and NC application to the skin resulted in a lower production of TGF-β compared to that of the control group. NF and NC might have protective effects to skin. Therefore, their potential use as components of skin-protective formulations merits consideration.
    01/2014; 101:464-70. DOI:10.1016/j.carbpol.2013.09.074
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    Kikumi Ogihara, Yuko Naya, Yoshiharu Okamoto, Keishi Hata
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    ABSTRACT: Canine melanoma is the most common oral malignant tumor reported in the field of veterinary medicine. We found that lupeol, a lupine triterpene, inhibited mouse melanoma cell growth in vitro and in vivo by inducing cell differentiation. In the present study, we examined the differentiation-inducing activities of lupeol on 4 canine melanoma cells in vitro and in vivo. The induction of canine melanoma cell differentiation by lupeol was confirmed by evaluating some differentiation markers such as tyrosinase with real-time RT-PCR. Furthermore, we transplanted canine melanoma cells into a severe combined immunodeficiency mouse, and studied the anti-progressive effects of lupeol on tumor tissue. The gene expression of microphthalmia-associated transcription factor, tyrosinase, and tyrosinase-related protein-2, which are markers of pigment cell differentiation, was induced in 4 canine oral malignant melanoma cells by lupeol, and the agent markedly inhibited tumor progression in canine melanoma-bearing mice.
    SpringerPlus 01/2014; 3:632. DOI:10.1186/2193-1801-3-632
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    ABSTRACT: Water-soluble chitosan derivative-based nanoparticles (carboxymethyl chitosan-chitooligosaccharide nanoparticles (CMC-COS NP) and sulphated chitosan-chitooligosaccharide nanoparticles (SC-COS NP)) were prepared by the formation of polyelectrolyte complexes. SC-COS NP and CMC-COS NP both induced the proliferation of mouse fibroblasts, whereas they elicited dose-dependent inhibitory effects on the proliferation of both HeLa and mouse B16 melanoma cells. Injection of SC-COS NP and CMC-COS NP modulated serum Th cytokines and stimulated the proliferation of splenic lymphocytes (CD4+ and CD8+ T cells, CD19+ B cells and NK cells) in mice, indicating the ability of these particles to regulate both humoral and cell-mediated immune responses. These properties demonstrated their promising potential for application as biomedical materials.
    Journal of Experimental Nanoscience 01/2014; 9(8). DOI:10.1080/17458080.2012.733078 · 1.04 Impact Factor
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    ABSTRACT: Sixteen cases of malignant soft tissue sarcoma (STS) (10 canine and 6 feline) were treated with a novel triple therapy that combined photodynamic therapy, hyperthermia using indocyanine green with a broad-band light source, and local chemotherapy after surgical tumor resection. This triple therapy was designated photodynamic hyperthermal chemotherapy (PHCT). In all cases, the surgical margin was insufficient. In one feline case, PHCT was performed without surgical removal. PHCT was performed over an interval of 1 to 2 weeks and was repeated 3 to 21 times. No severe side effects, including severe skin burns, necrosis, or rupture of skin sutures, were observed in any of the animals. No recurrence was observed in 7 of 10 (70.0%) dogs and 3 of 6 (50.0%) cats over follow-up periods ranging from 286 to 1901 days. These results suggest that PHCT decreases the risk of recurrence. PHCT should therefore be considered an adjuvant therapy for STS in companion animal medicine.
    Journal of veterinary science (Suwŏn-si, Korea) 10/2013; 15(1). DOI:10.4142/jvs.2014.15.1.117 · 1.14 Impact Factor
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    ABSTRACT: Previously, anti-inflammatory effect of α-chitin nanofibrils in experimental inflammatory-bowel disease (IBD) were demonstrated. In the present study, we evaluated the differences of the biological effects between α-NF and β-chitin nanofibrils (β-NF) using a mouse model of IBD. Although α-NF and β-NF suppressed the shorten colon lengths, only α-NF, suppressed the increase of colon weight/length ratio. α-NF significantly suppressed the increases of histological scores and number of myeloperoxidase-positive cells. Furthermore, α-NF significantly decreased the positive areas of nuclear factor-κB (NF-κB) and the areas of fibrosis. On the other hand, the β-NF group did not show anti-inflammatory effects in experimental IBD mouse model. Our results suggested that the -crystal structure is crucial for chitin nanofibrils to show anti-inflammatory effect. Further investigation is needed to elucidate the biological functions of chitin.
    09/2013; 1(2):144-149. DOI:10.1166/jcc.2013.1020
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    ABSTRACT: We herein describe the establishment of single hepatic lesions of Echinococcus multilocularis in rats. A 3mm incision was made on the liver with a surgical knife, and one small round vesicle of E. multilocularis (between 1×1mm and <2×2mm in diameter) was transplanted into the incision and covered with absorbable hemostat gauze. The presence and growth of the transplanted vesicle was monitored for 12weeks using magnetic resonance imaging (MRI). Hepatic lesions, the metacestode of this parasite were confirmed in 12 of 17 infected rats (70.6%) by MRI and macroscopic examinations. The average size of the metacestodes with brood capsules at 12weeks after the experimental transplantation of a single vesicle was 6.1±2.5mm×4.4±1.5mm. The smallest size of the metacestodes detected by MRI was approximately 3×3mm. This new approach of establishing single hepatic metacestodes of E. multilocularis in experimental animals is expected to be useful for analyzing the immune-pathological mechanisms of hepatic AE.
    Experimental Parasitology 07/2013; 135(2). DOI:10.1016/j.exppara.2013.07.015 · 1.86 Impact Factor