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Biomedical subjects

M Sakamoto

Publications and source records attributed to M Sakamoto.

At least 19 recordsLinked to original sources
PubMed2006

A novel keratinase from Clostridium sporogenes bv. pennavorans bv. nov., a thermotolerant organism isolated from solfataric muds.

A bacterium which can grow on chicken feathers and which exhibits keratinolytic activity was isolated from solfataric muds. It was classified as belonging to the genus Clostridium and closely related to C. sporogenes. Based on its unique capability to degrade chicken feathers, it was designated as Clostridium sporogenes bv. pennavorans bv. nov. The keratinase purified from the culture supernatant is a monomer of 28.7kDa molecular mass. The enzyme is relatively thermostable and is active over a broad range of temperature and pH. Specific enzymatic assays demonstrate that keratinase can act on a large variety of soluble and insoluble protein substrates.

Anaerobiosis↗
PubMed2006

Gene therapy of liver tumors with human liver-specific nanoparticles.

The development of safe and efficient liver-specific gene delivery approaches offers new perspectives for the treatment of liver disease, in particular, liver cancer. We evaluated the therapeutic potential of hepatotropic nanoparticles for gene therapy of liver tumor. These nanoparticles do not contain a viral genome and display the hepatitis B virus L antigen, which is essential to confer hepatic specificity. It has not been shown whether a therapeutic effect could be obtained using L nanoparticles in a human liver tumor xenograft model. Rats bearing human hepatic (NuE) and non-hepatic tumors were injected with L nanoparticles containing a green fluorescent protein (GFP) expression plasmid. GFP expression was observed only in NuE-derived tumors but not in the non-hepatic tumor. The potential for treatment of liver tumors was analyzed using L nanoparticles containing the herpes simplex virus thymidine kinase gene, in conjunction with ganciclovir pro-drug administration. The growth of NuE-derived tumors in L particle-injected rats was significantly suppressed, but not of the non-hepatic tumor control. In summary, this is the first demonstration that nanoparticles could be used for delivery of therapeutic genes with anti-tumor activity into human liver tumors. This intravenous delivery system may be one of the major advantages as compared to many other viral vector systems.

Animals↗
PubMed2006

Heating by an electron Bernstein wave in a spherical tokamak plasma via mode conversion.

The first successful high power heating of a high dielectric constant spherical tokamak plasma by an electron Bernstein wave (EBW) is reported. An EBW was excited by mode conversion (MC) of an mode cyclotron wave injected from the low magnetic field side of the TST-2 spherical tokamak. Evidence of electron heating was observed as increases in the stored energy and soft x-ray emission. The increased emission was concentrated in the plasma core region. A heating efficiency of over 50% was achieved, when the density gradient in the MC region was sufficiently steep.

Journal Article↗
PubMed2006

Morphological and histopathological changes in tongues of experimentally developed acromegaly-like rats.

An acromegaly-like rat model recently developed by exogenous administration of insulin-like growth factor I (IGF-I) was used to investigate morphological and histopathological tongue changes and clarify whether the changes were reversible. Human recombinant IGF-I (640 microg/day) was continuously subcutaneously infused into ten-week-old male rats for four weeks (IGF-I group; n = 6). Control sham-operated animals were injected saline alone (control group; n = 6). Rats were sacrificed immediately on ending administration at the age of fourteen weeks. Another 12 rats (6 from each group) were housed for an additional four weeks after administration ended. Total IGF-I (human + rat) increased significantly during administration, returning to control levels afterwards. Tongue weights significantly increased with histopathological changes present (increases in the muscle-bundle width, spaces between muscle-bundles and epithelium thickness) in the IGF-I group compared to control rats. Tongue size returned to control levels after discontinuation of IGF-I administration. These findings suggest that the characteristic tongue enlargement was developed experimentally in our acromegaly-like rat model, and that such morphological and histopathological tongue changes are reversible on normalization of circulating IGF-I levels.

Acromegaly↗
PubMed2006

Molecular analysis of bacteria in asymptomatic and symptomatic endodontic infections.

The purpose of the present study was to use terminal restriction fragment length polymorphism analysis and the 16S rRNA gene clone library to investigate the diversity of the microbiota associated with asymptomatic and symptomatic endodontic infections and to compare the bacterial community structure in these two clinical conditions. Samples were taken from asymptomatic endodontic infections associated with chronic periradicular lesions and from symptomatic infections clinically diagnosed as acute abscesses. 16S rRNA genes from DNA isolated from clinical samples were used to construct clone libraries or were subjected to terminal restriction fragment length polymorphism analysis. Sequence analysis of 186 clones revealed 42 taxa; 23 (55%) were uncultivated phylotypes, of which seven were unique to endodontic infections. Clone sequencing and terminal restriction fragment length polymorphism analysis revealed that the most commonly detected taxa were Fusobacterium nucleatum (including terminal restriction fragment types 1 and 2), Peptostreptococcus micros/Peptostreptococcus sp. oral clone AJ062/BS044/FG014, Prevotella species, Dialister species, Mogibacterium species, Lachnospiraceae oral clone 55A-34, Filifactor alocis, Megasphaera sp. oral clone CS025/BS073, and Veillonella sp. oral clone BP1-85/Veillonella dispar/V. parvula. Bacteroides-like sp. oral clone X083/Bacteroidales oral clone MCE7_20 and Dialister sp. oral clone BS016/MCE7_134 were detected only in asymptomatic teeth. On the other hand, F. nucleatum terminal restriction fragment type 2, Prevotella intermedia, Dialister pneumosintes, and some phylotypes were exclusively detected in symptomatic samples. Bacterial profiles of symptomatic endodontic infections generated by terminal restriction fragment length polymorphism analysis were clearly different from those of asymptomatic infections. Overall, the average number of terminal restriction fragments in symptomatic samples was significantly larger than in asymptomatic samples. Molecular analysis of the microbiota associated with symptomatic or asymptomatic endodontic infections indicates that the endodontic bacterial diversity is greater than previously described by culture methods and that the structure of the microbiota differ significantly between asymptomatic and symptomatic infections.

Adolescent↗
PubMed2006

Comparison of several methods for BAP measurement.

It has been more important for management of water quality to estimate the amount of bioavailable phosphorus (BAP) in suspended solids (SS) entering lakes and estuaries. AGP test or extraction by 0.1 mol l(-1) NaOH (C-BOD) is widely used. Recently, highly bioavailable phosphorus (HBAP) was introduced to indicate a more easily soluble and bioavailable fraction using successive extraction by 0.1 mol l(-1) HCl and 0.1 mol l(-1) NaOH. New biologically measured BAP (B-BAP) using bacterial respiration activity was introduced in this paper. B-BAP was estimated from oxygen uptake rate (OUR), which was measured by a respiratory meter for BOD measurement using a pressure sensor. B-BAP is useful for a rapid and direct measurement of phosphorus bioavailability. B-BAP, HBAP and C-BAP in river SS were measured and compared with each other. The percentages of HBAP and B-BAP to PP were large in the urban river, while the percentage of NaOH-P or C-BAP was large in the rivers flowing in agricultural areas. By comparison with phosphorus fractions in paddy soil and activated sludge it was suggested that SS in the rivers flowing in agricultural areas mainly consisted of clay, silt or sand, while the SS in the urban river consisted of a large percentage of organic particles as well. Phosphorus in SS was suggested to be more easily bioavailable in the urban river than the rivers in agricultural areas. The ratio of C-BAP/B-BAP was large in the rivers in agricultural areas and small in the urban river. As HBAP contents were almost similar to B-BAP contents in the river SS, HBAP can be a suitable index of phosphorus indicating easily and rapidly the bioavailable fraction in SS.

Environmental Monitoring↗
PubMed2006

Diffusion anisotropy and diffusivity of white matter tracts within the temporal stem in Alzheimer disease: evaluation of the "tract of interest" by diffusion tensor tractography.

PURPOSE: Our aim was to determine whether diffusion anisotropy and diffusivity of white matter tracts of the temporal stem in patients with Alzheimer (AD) can be evaluated independently by using diffusion tensor tractography. MATERIALS AND METHODS: Subjects included 15 patients with AD (11 women and 4 men; mean age, 74 years) and 15 age-matched control subjects (11 women and 4 men; mean age, 72 years). Diffusion tensor images were acquired by using echo-planar imaging. We drew tractographies of the uncinate fasciculus, inferior occipitofrontal fasciculus, and Meyer's loop, with diffusion tensor analysis software. We measured diffusion anisotropy, diffusivity, and the number of voxels along the "tracts of interest" and used the Student t test to compare results between patients with AD and controls. RESULTS: Values of diffusion anisotropy of the bilateral uncinate fasciculus and left inferior occipitofrontal fasciculus were significantly lower for patients with AD than for controls. Also, values of diffusivity in the bilateral uncinate fasciculus were significantly greater for patients with AD than for controls. There was no significant difference in diffusion anisotropy or diffusivity along Meyer's loop between the 2 groups. There was no significant difference in the number of voxels included in all constructed tracts between patients with AD and controls. CONCLUSION: White matter tracts of the temporal stem can be evaluated independently by using diffusion tensor tractography, which appears to be a promising technique for determining changes in white matter in degenerative diseases.

Aged↗
PubMed2005

Impact of pesticide application on zooplankton communities with different densities of invertebrate predators: an experimental analysis using small-scale mesocosms.

We assessed the responses of zooplankton communities with different population densities of an invertebrate predator, Mesocyclops pehpeiensis, to insecticide (carbaryl, 0.5 mgL(-1)) in small-scale mesocosm tanks (20 L). Cladocerans were eliminated by carbaryl application at both high and low predator densities. The density of rotifers increased after the elimination of the cladocerans by carbaryl application at low-predator density but not at high-predator density. Carbaryl application increased the relative importance of predatory interactions in the zooplankton community. The results suggest that predator abundance can affect the response of a zooplankton community to carbaryl application through predation on surviving zooplankton.

Analysis of Variance↗
PubMed2005

Mucosa-associated bacteria in ulcerative colitis before and after antibiotic combination therapy.

BACKGROUND: We proposed that Fusobacterium varium is one of the causative agents in ulcerative colitis. AIM: To examine the efficacy of antibiotic combination therapy against F. varium and to investigate the mucosa-associated bacteria before and after the therapy using a new molecular approach. METHODS: Twenty patients with ulcerative colitis were randomly assigned into the antibiotic treatment group (amoxicillin, tetracycline and metronidazole for 2 weeks) and no-antibiotics group. Clinical assessment, colonoscopic and histological evaluations were performed at 0 and 3-5 months after the treatment. DNA from mucosal bacteria was isolated from biopsy specimens. We investigated the mucosa-associated bacterial components by terminal restriction fragment length polymorphism with the restriction enzyme HhaI and MspI, and quantified the change in the number of bacteria by real-time polymerase chain reaction. Immunohistochemical detection of F. varium in biopsy specimens was also performed. RESULTS: After the treatment, the clinical assessment, colonoscopic and histological scores improved in the antibiotic group compared with the control group. Three peaks of terminal restriction fragment length polymorphism decreased after treatment only in the antibiotic group. Eubacterium rectale, Dorea formicigenerans, Clostridium clostridioforme and F. varium were included in these peaks. Based on the real-time polymerase chain reaction study, only F. varium was significantly reduced after treatment. In the immunostaining, post-treatment scores in treatment group were significantly lower than that in control group. CONCLUSIONS: Antibiotics combination therapy was effective for ulcerative colitis. The number of mucosa-associated F. varium significantly decreased after the treatment.

Amoxicillin↗
PubMed2005

Attenuation of the effect of remote muscle contraction on the soleus H-reflex during plantar flexion.

OBJECTIVE: We investigated to what extent the facilitation of the soleus (Sol) Hoffmann (H-) reflex during a phasic voluntary wrist flexion (Jendrássik maneuver, JM) can be modulated by graded plantar flexion force and conditioning wrist flexion force. METHODS: The subjects were asked to perform phasic wrist flexion under a reaction time condition. Sol H-reflex was evoked by stimulating the right tibial nerve at various time intervals (50-400ms) after the 'Go' signal for initiating JM while the ankle was at rest and while plantarflexing. The level of tonic plantar flexion force (isometric contraction of 10, 20 and 30% of maximal EMG) and conditioning wrist flexion (isometric contraction of 30, 50 and 80% of maximum voluntary contraction) during JM was graded systematically. RESULTS: Although JM facilitation could be seen 80-120ms after the flexor carpi radialis (FCR) EMG onset even while plantarflexing, the magnitude of JM facilitation under plantar flexion was significantly decreased compared to that at rest. The degree of decrease in JM facilitation did not depend on the level of plantar flexion force. In contrast, the degree of JM facilitation was proportional to the level of wrist flexion force while the ankle was at rest and while plantarflexing, though the amount of JM facilitation significantly decreased while plantarflexing. CONCLUSIONS: JM facilitation of Sol H-reflex is decreased while performing tonic voluntary contraction of the homonymous muscle. The degree of decrease in JM facilitation is independent of the level of homonymous muscle contraction, but depends on the level of remote FCR contraction. In clinical application, when we intend to elicit a maximum stretch reflex by JM, full relaxation of homonymous muscle should be carefully confirmed. SIGNIFICANCE: Our results provide evidence for better understanding of the features of JM and insight into its clinical application.

Acoustic Stimulation↗
PubMed2005

Toroidal plasma rotation induced by the dynamic ergodic divertor in the TEXTOR tokamak.

The first results of the Dynamic Ergodic Divertor in TEXTOR, when operating in the m/n=3/1 mode configuration, are presented. The deeply penetrating external magnetic field perturbation of this configuration increases the toroidal plasma rotation. Staying below the excitation threshold for the m/n=2/1 tearing mode, this toroidal rotation is always in the direction of the plasma current, even if the toroidal projection of the rotating magnetic field perturbation is in the opposite direction. The observed toroidal rotation direction is consistent with a radial electric field, generated by an enhanced electron transport in the ergodic layers near the resonances of the perturbation. This is an effect different from theoretical predictions, which assume a direct coupling between rotating perturbation and plasma to be the dominant effect of momentum transfer.

Journal Article↗
PubMed2005

Tandem mass spectrometry method for the quantification of serum busulfan.

Busulfan, an alkylating agent, is most commonly used as a component of bone marrow transplantation preoperative regimens. Significant interpatient and intrapatient variations in pharmacokinetics require individualizing the dosage based on area under the time-versus-concentration curve. Timely result reporting is critical to dose adjustment to reduce morbidity and mortality associated with the regimen. The authors developed a rapid, accurate, and sensitive method for the quantification of serum busulfan using direct inject tandem mass spectrometry. Plasma samples (50 microL) are extracted in 1 mL of methanol containing 1,6-bis-(methanesulfonyloxy)hexane as an internal standard. The supernatant is dried under nitrogen (40 degrees C, 30 minutes) and then dissolved in 200 microL methanol and transferred into a clean glass vial suitable for LC/MS/MS analysis. The sample is delivered using an HPLC pump that delivers 0.2 mL of methanol per minute, and 20 microL of sample is injected into a turbo ion spray-equipped tandem mass spectrometer. Total analysis time is 5 minutes. The Q1/Q3 transition for busulfan (BU) is monitored at 269/55 and 297.1/55.1 for the internal standard. The assay is linear to 10 micromol/L and sensitive to at least 0.5 micromol/L. The interassay reproducibility at 1, 2.2, and 4.4 micromol/L were 4.2%, 5.6%, and 6.3%, respectively. Within-run precision using 3 different control samples was 3.9%, 3.9%, and 6.9%. Mean recovery of 4 different BU concentrations spiked into 10 different BU free plasma samples was 98%. Correlation with an established HPLC-UV method revealed a slope of 0.98, an intercept of 0.1, and r = 0.95 (n = 48). No significant interfering substances or ion suppression was identified. This method is a significant improvement over the existing HPLC-UV method for BU determination. The method is highly accurate, reproducible, and requires less specimen, sample preparation, and analysis time.

Antineoplastic Agents, Alkylating↗
PubMed2005

Improvement of portal hypertension and hepatic blood flow in cirrhotic rats by oestrogen.

BACKGROUND: In this study, we investigated the effects of oestrogen on nitric oxide synthase activity and nitric oxide production using the cirrhotic rat liver. MATERIAL AND METHODS: Cirrhosis was induced by dimethylnitrosamine. Estradiol valerate was subcutaneously injected twice at week 4 after dimethylnitrosamine treatment. Furthermore, subcutaneous injection of an oestrogen receptor antagonist, ICI-182.780, was performed 2 days before administration of estradiol valerate. Portal pressure and hepatic blood flow were measured. Nitric oxide synthase activity was assessed by l-citrulline generation. Sinusoidal endothelial cells were isolated from the cirrhotic rat liver and cultured. The cells were incubated with estradiol and/or ICI-182.780 for 24 h. Images for nitric oxide in sinusoidal endothelial cells were obtained using diaminofluorescein-2 diacetate. RESULTS: Cirrhotic rats treated with estradiol valerate showed a significant decrease in portal pressure and a significant increase in hepatic blood flow compared with those of control cirrhosis rats. However, in cirrhotic rats treated with ICI-182.780, the reduction of portal pressure and elevation of hepatic blood flow were completely inhibited. In cirrhotic rats treated with estradiol valerate, nitric oxide synthase activity was increased compared with that in control cirrhotic rats. The fluorescent level of intracellular nitric oxide in estradiol-stimulated, cultured, sinusoidal endothelial cells was higher than that in nontreated sinusoidal endothelial cells. CONCLUSIONS: The present study indicated that oestrogen plays an important role in the enhancement of nitric oxide production in sinusoidal endothelial cells of cirrhotic liver and reduces the portal pressure in cirrhotic rats.

Animals↗
PubMed2005

Frequent importation of enterovirus 71 from surrounding countries into the local community of Yamagata, Japan, between 1998 and 2003.

Phylogenetic analysis of 45 enterovirus 71 (EV71) isolates for 6 years in Yamagata, Japan, clarified that the annual outbreak of hand-foot-and-mouth disease was due to four genetically distinct subgenogroups, including a novel "B5." Our results suggest that the importation of EV71 from surrounding countries has had a major epidemiological impact on the local community used in our study.

Capsid Proteins↗
PubMed2005

Extramedullary myeloid tumour (EMMT) of the gallbladder.

This report describes a rare case of an extramedullary myeloid tumour (EMMT) of the gallbladder in a patient without leukaemia. A 33 year old man visited a local hospital because of jaundice. Abdominal computed tomography revealed a tumorous mass measuring 6.0 x 4.5 cm and involving the entire gallbladder. A percutaneous needle biopsy was attempted, but because adenocarcinoma could not be completely ruled out, the use of undue force was considered dangerous. Under a preoperative diagnosis of gallbladder carcinoma, a hepatopancreatoduodenectomy was performed. The tumour cells exhibited various amounts of eosinophilic cytoplasm, had medium sized round nuclei with indentation and grooving, and were strongly immunoreactive for myeloperoxidase, CD43, and c-kit protein (CD117). After surgery, the patient underwent combination chemotherapy as prescribed for cases of acute myeloblastic leukaemia. The patient did not develop acute leukaemia during a follow up period of four years. In conclusion, a correct diagnosis of EMMT can be made using appropriate immunohistochemical staining.

Adult↗
PubMed2005

The use of relaxin improves healing in injured muscle.

To improve the functional recovery of injured skeletal muscle, we have focused our efforts on both enhancement of muscle regeneration and prevention of fibrosis. The polypeptide cytokine/growth factor relaxin can inhibit fibrous tissue formation in many tissues. As a member of the insulin-like growth factor family, relaxin also is a potential stimulator of muscle regeneration. In the current experiment, we examined the antifibrotic effect of relaxin in injured skeletal muscle. We also investigated if the injection of relaxin would influence muscle regeneration after injury. Our results demonstrate that relaxin treatment improved histologic and physiologic healing of muscles subjected to traumatic injury.

Animals↗
PubMed2005

[Two-stage repair of the transposition of great arteries with interruption/coarctation of the aorta].

We report on 10 patients who underwent two-stage repair of transposition of the great arteries (TGA) with interruption (IAA) or coarctation (CoA) of the aorta. First, an operation for aortic arch reconstruction was performed: Blalock-Park with pulmonary artery banding (PAB) for IAA (5 patients), subclavian flap with PAB for CoA (4 patients) and end-to-end anastomosis without PAB (1 patient). All survived the first operation and had no significant pressure gradient with good growth of the ascending aorta, except for the 1 case without PAB. Half of the 8 patients who underwent PAB developed migration of the PAB. The arterial switch operation (ASO) was performed 0.7-12.6 (5.6+/-4.7) months after the first surgery. One patient with an abnormal coronary artery tract was lost after ASO. Five developed pulmonary artery stenosis and 1 developed supra-aortic stenosis late after ASO. Two patients need reoperation, 1 for supra-aortic stenosis, and the other for reCoA. Two-stage repair for TGA with IAA/CoA is still a useful method with a good operative result. However, strict follow-up is necessary because of the high frequency of late morbidity.

Aorta, Thoracic↗