Publications by authors named "Masatoshi Ohta"

9 Publications

  • Page 1 of 1

Electron spin resonance spectral analysis of irradiated royal jelly.

Food Chem 2014 Jan 9;143:479-83. Epub 2013 Aug 9.

Osaka University of Pharmaceutical Sciences, 4-20-1 Nasahara, Takatsuki, Osaka 569-1094, Japan. Electronic address:

The analysis of unpaired electron components in royal jelly was carried out using electron spin resonance (ESR) with the aim to develop a detection method for irradiated royal jelly. The ESR spectrum of royal jelly had natural signals derived from transition metals, including Fe(3+) and Cu(2+), and a signal line near g=2.00. After irradiation, a new splitting asymmetric spectrum with overall spectrum width ca. 10mT at g=2.004 was observed. The intensities of the signals at g=2.004 increased in proportion to the absorbed dose in samples under different storage conditions: fresh frozen royal jelly and dried royal jelly powder at room temperature. The signal intensity of the fresh frozen sample was stable after irradiation. One year after 10kGy irradiation of dried powder, the signal intensity was sevenfold greater than before irradiation, although the intensity continued to steadily decrease with time. This stable radiation-induced radical component was derived from the poorly soluble constituent of royal jelly.
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http://dx.doi.org/10.1016/j.foodchem.2013.07.139DOI Listing
January 2014

Self-enhancement of hepatitis C virus replication by promotion of specific sphingolipid biosynthesis.

PLoS Pathog 2012 16;8(8):e1002860. Epub 2012 Aug 16.

Department of Microbiology and Cell Biology, Tokyo Metropolitan Institute of Medical Science, Setagaya-ku, Tokyo, Japan.

Lipids are key components in the viral life cycle that affect host-pathogen interactions. In this study, we investigated the effect of HCV infection on sphingolipid metabolism, especially on endogenous SM levels, and the relationship between HCV replication and endogenous SM molecular species. We demonstrated that HCV induces the expression of the genes (SGMS1 and 2) encoding human SM synthases 1 and 2. We observed associated increases of both total and individual sphingolipid molecular species, as assessed in human hepatocytes and in the detergent-resistant membrane (DRM) fraction in which HCV replicates. SGMS1 expression had a correlation with HCV replication. Inhibition of sphingolipid biosynthesis with a hepatotropic serine palmitoyltransferase (SPT) inhibitor, NA808, suppressed HCV-RNA production while also interfering with sphingolipid metabolism. Further, we identified the SM molecular species that comprise the DRM fraction and demonstrated that these endogenous SM species interacted with HCV nonstructural 5B polymerase to enhance viral replication. Our results reveal that HCV alters sphingolipid metabolism to promote viral replication, providing new insights into the formation of the HCV replication complex and the involvement of host lipids in the HCV life cycle.
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http://dx.doi.org/10.1371/journal.ppat.1002860DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3420934PMC
December 2012

Detection of organic free radicals in irradiated Foeniculi fructus by electron spin resonance spectroscopy.

J Nat Med 2009 Jan 1;63(1):28-31. Epub 2008 Aug 1.

Osaka University of Pharmaceutical Sciences, 4-20-1 Nasahara, Takatsuki, Osaka, 569-1094, Japan.

Foeniculi fructus were irradiated with an electron beam and organic free radicals were detected by electron spin resonance (ESR) spectroscopy for the purpose of identifying radio-disinfected and sterilized herbal drugs. An ESR single-line spectrum near g = 2.005 was observed in the sample before irradiation. After irradiation, the intensity of the signal near g = 2.005 increased. In addition, two subsignals derived from cellulose radicals were observed approximately 3 mT to either side of the main signal, at g = 2.023 and g = 1.987. The intensity of the subsignal at g = 2.023 was proportional to the absorbed dose of radiation. The decrease in intensity of the signals was considerable 2 weeks after irradiation, and continued to decrease steadily thereafter. Among the signals, the fading of the subsignal at g = 2.023 was relatively small. The intensity of the subsignal at g = 2.023 was detectable for over 1 year in the sample that had been irradiated to the level of disinfection and sterilization. Therefore, organic free radicals in irradiated Foeniculi fructus can be measured rapidly and with high sensitivity by ESR spectroscopy. The stable signal at g = 2.023 is a promising indicator of the detection of irradiated herbal drugs.
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http://dx.doi.org/10.1007/s11418-008-0284-6DOI Listing
January 2009

A new entry to carbocyclic nucleosides: oxidative coupling reaction of cycloalkenylsilanes with a nucleobase mediated by hypervalent iodine reagent.

Org Lett 2008 Aug 10;10(16):3449-52. Epub 2008 Jul 10.

Faculty of Pharmaceutical Sciences, Tohoku Pharmaceutical University, 4-4-1 Komatsushima, Aoba-ku, Sendai 981-8558, Japan.

A novel method for synthesizing carbocyclic nucleosides was developed. The new synthesis includes a direct coupling reaction of cycloalkenylsilanes with a silylated nucleobase catalyzed by a hypervalent iodine reagent. By applying the method, a novel carbocyclic cytidine derivative having bis(hydroxymethyl)cyclohexene as a pseudosugar moiety, designed as a potential anti-HIV agent, was successfully synthesized.
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http://dx.doi.org/10.1021/ol8012155DOI Listing
August 2008

Evaluation of clinical efficacy of Maeda's nomogram for vancomycin dosage adjustment in adult Japanese MRSA pneumonia patients.

Drug Metab Pharmacokinet 2006 Feb;21(1):54-60

Department of Pharmacy, Okayama Rousai General Hospital, Japan.

The clinical efficacy of Maeda's nomogram for vancomycin dosage adjustment was evaluated by comparison with a standard dosage regimen (package insert information: vancomycin dose reduced in elderly patients and patients with renal dysfunction, with Moellering's nomogram used for renal-dysfunction patients) in adult Japanese MRSA pneumonia patients. Using Maeda's nomogram, the vancomycin dose is fixed at 1,000 mg while the dosing interval is varied in accordance with individual creatinine clearance. Using a standard dosage regimen, 5 patients out of 27 (18.5%) achieved target plasma levels of vancomycin (25-40 microg/mL for peak and 5-15 microg/mL for trough) within 2-6 days. Using Maeda's nomogram, 38 patients out of 53 (71.7%) achieved target levels in that time. A higher clinical response (complete resolution of all signs and symptoms of MRSA infection) to vancomycin therapy was also obtained with Maeda's nomogram when evaluated approximately 2-weeks after discontinuation of vancomycin therapy (43.4% versus 18.5% for the standard regimen). In conclusion, the Maeda's nomogram regimen with a 1,000 mg vancomycin dose was shown to achieve target plasma levels of vancomycin at a higher rate and provide higher clinical efficacy in vancomycin therapy of MRSA pneumonia patients, as compared with the currently available standard dosage regimen.
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http://dx.doi.org/10.2133/dmpk.21.54DOI Listing
February 2006

Combination of trastuzumab and vinorelbine in metastatic breast cancer.

Jpn J Clin Oncol 2003 Oct;33(10):514-7

Department of Surgery, Tokai University School of Medicine, Isehara, Kanagawa, Japan.

Background: Since the clinical introduction of trastuzumab (Herceptin) for metastatic breast cancers that overexpress human epidermal growth factor receptor 2 (HER2), this anticancer agent has played an important role in breast cancer treatment. We examined the effects of trastuzumab and vinorelbine (Navelbine) as a second- or third-line therapy in 24 patients whose HER2-positive tumors did not respond to or relapsed after administration of trastuzumab alone or in combination with taxane.

Methods: Trastuzumab was administered at 2 mg/kg (loading dose 4 mg/kg) once weekly and vinorelbine at 25 mg/m(2) once weekly. The median treatment duration was 118.5 days (range, 22-351 days).

Results: The response rate was 42% (95% confidence interval (CI): 22%-63%). The adverse events of NCI-CTC grade 3 or above consisted of neutropenia in three patients; other adverse events, including vasculitis, generalized fatigue, anemia and thrombocytopenia, were grade 1 or 2. All adverse events were reversible after treatment withdrawal and were easily manageable.

Conclusion: A combination of trastuzumab and vinorelbine can be safely administered on an outpatient basis, and is useful in the treatment of patients with HER2-overexpressing metastatic breast cancer.
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http://dx.doi.org/10.1093/jjco/hyg101DOI Listing
October 2003

Immunohistochemical evaluation of hormone receptor for routine practice of breast cancer: highly sensitive procedures significantly contribute to the correlation with biochemical assays.

Appl Immunohistochem Mol Morphol 2003 Mar;11(1):62-72

Department of Pathology, Tokai University School of Medicine, Bohseidai, Isehara, 259-1193 Kanagawa, Japan.

Immunohistochemical evaluation of hormone receptors for breast cancer has been performed parallel to biochemical assays. Recently, immunohistochemistry has tended to substitute the biochemical method in Japan. To clarify the factors concerned and problems to be resolved, we reviewed our evaluation system for hormone receptors by immunohistochemistry from 1990. A total of 861 breast cancer samples were examined by immunohistochemistry and biochemistry. In 3 main periods, phase 1 (1990-1993), phase 2 (1995-1998), and phase 3 (1999-2001), increasing sensitivity of the immunohistochemical method was provided by commercially available staining systems and shown to range from 83.6% (phase 1) to 92.0% (phase 3). The highly sensitive procedures of the antigen retrieval and peroxidase-conjugated polymer method are main contributing factors. The authors examined how these procedures influenced the distribution of positive cell population; concordance rate, including sensitivity and specificity; cutoff points; and evaluation categories. The correlation between biochemistry and immunohistochemistry was extensively studied in the 1980s and 1990s. In reference to the progress achieved in the United States and United Kingdom to control the current situation in Japan, it should be recognized that recently developed, highly sensitive procedures boost the immunoreactivity, which will affect the basic factors for technical validation.
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http://dx.doi.org/10.1097/00129039-200303000-00011DOI Listing
March 2003

[Trastuzumab (Herceptin)].

Gan To Kagaku Ryoho 2002 Apr;29(4):645-52

Department of Surgery, Tokai University School of Medicine, 143 Shimokasuya, Isehara, Kanagawa 259-1193, Japan.

The HER 2/neu protein is thought to be a unique and useful molecular target for antibody therapy of cancers overexpressing the HER 2/neu gene. The recombinant humanized anti-HER 2 monoclonal antibody trastuzumab (Herceptin) has been available for clinical use in metastatic breast cancer in Japan since June 2001. Some breast cancer patients have responded to trastuzumab alone. A phase III study showed significant efficacy of combination use with paclitaxel compared with paclitaxel alone. Trastuzumab has some toxicities including infusion reaction and cardiotoxicity. It is very rare that infusion reaction manifests lethally. Although trastuzumab should not be concurrently used with an anthracycline, cardiotoxicity was also identified in patients treated with trastuzumab alone. The cumulative dose of anthracycline has not yet been identified as a risk factor, but patients who have received a high cumulative dose should be treated with special caution. In this article, the details of this novel biologic agent are reviewed from basic and clinical studies.
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April 2002

[Breast cancer].

Nihon Rinsho 2002 Mar;60(3):563-9

Department of Breast and Endocrine Surgery, Tokai University School of Medicine.

The HER2/neu protein is thought to be a unique and useful target for antibody therapy of cancers overexpressing the HER2/neu gene. The recombinant humanized anti-HER2 monoclonal antibody, trastuzumab(Herceptin) has recently been available for clinical use in Japan. In this paper, the details of this novel biologic agent are reviewed in conjunction with the results of the clinical trials for breast cancer.
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March 2002