Biomedical subjects

A Hirata

Publications and source records attributed to A Hirata.

At least 19 recordsLinked to original sources

PubMed2006

Local structure studies of Fe-Nb-B metallic glasses using electron diffraction.

Local atomic structures in Fe(84)Nb(7)B(9) and Fe(70)Nb(10)B(20) amorphous alloys were examined by means of electron diffraction with the help of computer calculation. Electron diffraction patterns were taken by using energy-filtered transmission electron microscopy (TEM) to eliminate inelastic scattering. We constructed structure models with 5000 atoms fitting to experimental interference functions. Voronoi polyhedral analyses were performed for the obtained final structure models. Local atomic structures of the alloys were closely related to those of the crystalline phases that appeared on annealing. A difference of stability of two amorphous phases was discussed on the basis of structure models.

Journal Article↗

PubMed2006

Characteristics of bacteria showing high denitrification activity in saline wastewater.

AIMS: Denitrification efficiency at 10% salinity was compared with that at 2% salinity. The characteristics of bacterial strains isolated from the denitrification system, where an improvement of denitrification efficiency was observed at a high salinity were investigated. METHODS AND RESULTS: Two continuous feeding denitrification systems for saline solutions of 2% and 10% salinity, were operated. Denitrification efficiency at 10% salinity was higher than that at 2% salinity. The bacterial strains were isolated using the trypticase soy agar (TSA) medium at 30 degrees C. The phylogenetic analysis of 16S rRNA gene sequences of isolates indicated that halophilic species were predominant at 10% salinity. CONCLUSIONS: The improvement of denitrification efficiency at a high salinity was demonstrated. The strains isolated from the denitrifying system with 10% salinity were halophilic bacteria, Halomonas sp. and Marinobacter sp., suggesting that these bacteria show a high denitrifying activity at 10% salinity. SIGNIFICANCE AND IMPACT OF THE STUDY: The long-term acclimated sludge used in this study resulted in high denitrification performance at a high salinity, indicating that the design of a high-performance denitrification system for saline wastewater will be possible.

Alteromonadaceae↗

PubMed2006

Morphological and immunohistochemical features of Cryptosporidium andersoni in cattle.

Light and electron microscopic features and immunohistochemical features of Cryptosporidium andersoni (C. andersoni) and host reaction in the mucosa were studied. Although the affected cattle demonstrated no apparent clinical signs, a severe infection of C. andersoni was observed in the abomasum. C. andersoni were round in shape, measured 6-8 microm in size and were mainly observed to be freely located in the gastric pits, being attached in occasional cases to the surface of the abomasum epithelium. Frequent inflammatory cells had infiltrated the lamina propria of the affected mucosa, and frequent mitotic figures were observed in epithelial cells at the dilated isthmus. To access the cell kinetics, the number of epithelial cells infected with C. andersoni were counted and compared with noninfected cattle. The number of gastric pit cells in infected cattle was significantly higher than that in the controls. The number of proliferative cells determined by the Ki-67 antigen in C. andersoni infected cattle was also significantly higher than that in the controls. Transmission electron microscopy and scanning electron microscopy revealed that the morphology of the C. andersoni organism was common to those of other Cryptosporidium spp. Immunohistochemically, several commercial antibodies against Cryptosporidium spp. showed positive reactions at the wall of these oocysts or parasitophorous vacuoles. This report is possibly the first to discuss the prominent hyperplasia of the abomasum mucosa, as well as morphologic features of C. andersoni in cattle.

Abomasum↗

PubMed2006

High-rate nitrification using aerobic granular sludge.

The performance of nitrifying granules, which had been produced in an aerobic upflow fluidised bed (AUFB) reactor, was investigated in various types of ammonia-containing wastewaters. When pure oxygen was supplied to the AUFB reactor with a synthetic wastewater containing a high concentration of ammonia (500 g-N/m3), the ammonia removal rate reached 16.7 kg-N/m3/day with a sustained ammonia removal efficiency of more than 80%. The nitrifying granules possessing a high settling ability could be retained with a high density (approximately 10,000 g-MLSS/m3) in a continuous stirring tank reactor (CSTR) even under a short hydraulic retention time (44 min), which enabled a high-rate and stable nitrification for an inorganic wastewater containing low concentrations of ammonia (50 g-N/m3). Moreover, the nitrifying granules exhibited sufficient performance in the nitrification of real industrial wastewater containing high concentrations of ammonia (1000-1400 g-N/m3) and salinity (1.2-2.2%), which was discharged from metal-refinery processes. When the nitrifying granules were used in cooperation with activated sludge to treat domestic wastewater containing organic pollutants as well as ammonia, they fully contributed to nitrification even though a part of activated sludge adhered onto the granule surfaces to form biofilms. These results show the wide applicability of nitrifying granules to various cases in the nitrification step of wastewater treatment plants.

Ammonia↗

PubMed2006

Evaluation of sludge reduction and phosphorus recovery efficiencies in a new advanced wastewater treatment system using denitrifying polyphosphate accumulating organisms.

A new biological nutrient removal process, anaerobic-oxic-anoxic (A/O/A) system using denitrifying polyphosphate-accumulating organisms (DNPAOs), was proposed. To attain excess sludge reduction and phosphorus recovery, the A/O/A system equipped with ozonation tank and phosphorus adsorption column was operated for 92 days, and water quality of the effluent, sludge reduction efficiency, and phosphorus recovery efficiency were evaluated. As a result, TOC, T-N and T-P removal efficiency were 85%, 70% and 85%, respectively, throughout the operating period. These slightly lower removal efficiencies than conventional anaerobic-anoxic-oxic (A/A/O) processes were due to the unexpected microbial population in this system where DNPAOs were not the dominant group but normal polyphosphate-accumulating organisms (PAOs) that could not utilize nitrate and nitrite as electron acceptor became dominant. However, it was successfully demonstrated that 34-127% of sludge reduction and around 80% of phosphorus recovery were attained. In conclusion, the A/O/A system equipped with ozonation and phosphorus adsorption systems is useful as a new advanced wastewater treatment plant (WWTP) to resolve the problems of increasing excess sludge and depleted phosphorus.

Adsorption↗

PubMed2005

Single-stage autotrophic nitrogen-removal process using a composite matrix immobilizing nitrifying and sulfur-denitrifying bacteria.

We developed a novel single-stage autotrophic nitrogen-removal process comprised of two composite immobilized biomass layers-one of nitrifying bacteria and one of sulfur-denitrifying bacteria and elemental sulfur-in a Fe-Ni fibrous slag matrix. Nitrification and consumption of dissolved oxygen occurred in the outer part and sulfur denitrification in the anoxic inner part of the composite matrix, thus realizing autotrophic nitrogen removal in a single reactor. The complete conversion of ammonia into N2 in a single reactor was demonstrated in both batch-mode incubation and continuous-feed operation. The spatial profiles of the ammonia-oxidizing bacteria and denitrifying bacteria were evaluated by real-time PCR, targeting their functional genes, and stratification of these two types was observed in the matrix after several months of incubation. This process does not require any specific reactor type or conditions and thus has the potential to be applied to many different wastewater treatment processes due to its simplicity in both operation and construction.

Aerobiosis↗

PubMed2005

Molecular analysis of microbial population transition associated with the start of denitrification in a wastewater treatment process.

AIMS: The objective of this study is to determine the bacteria playing an important role in denitrification by monitoring the molecular dynamics accompanying the start of denitrification. METHODS AND RESULTS: cDNA reverse-transcribed from 16S rRNA was amplified with fluorescent labelled primer for terminal restriction fragment length polymorphism (T-RFLP) analysis and an unlabelled primer for cloning analysis. The terminal restriction fragments (T-RFs) that increased in association with the start of denitrification were determined. These T-RFs were identified by in silico analysis of 16S rRNA sequences obtained from cloning. As a result, it was clearly observed that the bacteria belonging to the genera Hydrogenophaga and Acidovorax increased in number after the start of denitrification. CONCLUSIONS: It was demonstrated that T-RFLP analysis targeting 16S rRNA is appropriate for the daily monitoring of a bacterial community to control wastewater treatment processes. Combination of the results of T-RFLP analysis and 16S rRNA clone library indicated that the bacteria belonging to the genera Hydrogenophaga and Acidovorax play an important role in denitrification. SIGNIFICANCE AND IMPACT OF THE STUDY: The results of this study provide new insight to the 16S rRNA level of active denitrifying bacteria in wastewater treatment processes.

Bacteroides↗

PubMed2004

Comparative analysis of genetic diversity and expression of amoA in wastewater treatment processes.

The genetic diversity and expression of amoA of autotrophic ammonia oxidizers in wastewater treatment processes were investigated by RT-PCR and denaturing gradient gel electrophoresis (DGGE) in order to identify active components of ammonia-oxidizer populations in a such processes. Ammonia oxidizers, evidenced by the presence of amoA mRNA, were regarded as metabolically active. The DGGE profiles derived from amoA mRNA and from its gene, which were amplified by RT-PCR or PCR using samples collected from a bench-scale reactor treating high concentration of inorganic ammonia, were similar. In contrast, RNA and DNA-derived DGGE profiles from three domestic wastewater treatment facilities were different from each other. These data indicate that the dominant ammonia oxidizers in the bench-scale reactor exhibited ammonia-oxidizing activity, whereas some ammonia oxidizers in the domestic wastewater treatment facilities apparently did not express high levels of amoA mRNA.

Ammonia↗

PubMed2004

Assessment of proliferative potentials of canine osteosarcomas and chondrosarcomas by MIB-1 immunohistochemistry and bromodeoxyuridine incorporation.

The proliferative potential of 17 canine osteosarcomas (OSs) (13 osteoblastic, two anaplastic, one fibroblastic and one chondroblastic), 18 chondrosarcomas (CSs) (13 mesenchymal and five ordinary), three osteomas, and one chondroma was evaluated immunohistochemically by labelling Ki-67 antigen with MIB-1 antibody, and incorporated bromodeoxyuridine (BrdU) with anti-BrdU antibody. The location of BrdU-positive cells in OSs and CSs was similar to that of MIB-1 positive cells, and the mean value of the BrdU labelling index (BrdU LI) and the MIB-1 positive index (MIB-1 PI) in each case were significantly correlated (rs = 0.942, P < 0.05 with Spearman rank correlation coefficient; r = 0.779 P < 0.05 with linear regression analysis). The mean MIB-1 PI of OSs was 29.5%, which was approximately 2.5 times that of CSs, and the highest MIB-1 PI was 34.8% +/- 1.8 S.E.M. in areas without osteoid. In CS cases, the survival rate after 24 months was significantly higher than in OS cases. The high MIB-1 PI therefore supports the view that OSs are clinically more aggressive than CSs in dogs. On the other hand, the highest MIB-1 PI values of mesenchymal CS components occurred in transitional areas, which were composed of poorly differentiated cells embedded in a myxomatous matrix between the chondroidal and mesenchymal regions. The MIB-1 PI was 21.3% +/- 3.0 S.E.M. P < 0.001 in transitional areas. Proliferative markers may be useful in diagnosis and prognosis.

Animals↗

PubMed2004

Targeted conversion of the transthyretin gene in vitro and in vivo.

Familial amyloidotic polyneuropathy (FAP) is the common form of hereditary generalized amyloidosis and is characterized by the accumulation of amyloid fibrils in the peripheral nerves and other organs. Liver transplantation has been utilized as a therapy for FAP, because the variant transthyretin (TTR) is predominantly synthesized by the liver, but this therapy is associated with several problems. Thus, we need to develop a new treatment that prevents the production of the variant TTR in the liver. In this study, we used HepG2 cells to show in vitro conversion of the TTR gene by single-stranded oligonucleotides (SSOs), embedded in atelocollagen, designed to promote endogenous repair of genomic DNA. For the in vivo portion of the study, we used liver from transgenic mice whose intrinsic wild-type TTR gene was replaced by the murine TTR Val30Met gene. The level of gene conversion was determined by real-time RCR combined with mutant-allele-specific amplification. Our results indicated that the level of gene conversion was approximately 11 and 9% of the total TTR gene in HepG2 cells and liver from transgenic mice, respectively. Gene therapy via this method may therefore be a promising alternative to liver transplantation for treatment of FAP.

Amyloid Neuropathies↗

PubMed2004

Quantitative analysis of amoA mRNA expression as a new biomarker of ammonia oxidation activities in a complex microbial community.

AIMS: To quantitatively analyse the changes to amoA mRNA (ammonia mono-oxygenase encoding mRNA) profiles in response to a change in ammonia oxidation activity in a complex microbial community. METHODS AND RESULTS: The amoA mRNA levels in both a batch-mode incubation and a continuously fed nitrification reactor were determined by real-time reverse transcription-PCR analysis. The amoA mRNA level changed rapidly in response to the change in environmental conditions which affect ammonia oxidation activity. CONCLUSION: An increase in amoA mRNA level can be detected within 1-2 h in response to an initiation of cell activity whereas a decrease in amoA mRNA level is detected within 24 h in response to a cessation of activity. SIGNIFICANCE AND IMPACT OF THE STUDY: amoA mRNA, which shows sensitive response to ammonia oxidation activity, can be used as a biomarker of ammonia oxidation activity in wastewater treatment processes where many bacterial species exist.

Ammonia↗

PubMed2004

Expression of myogenic regulating factors, Myogenin and MyoD, in two canine botryoid rhabdomyosarcomas.

Myogenin and MyoD regulate the development of skeletal muscle, and their expressions are specific to the stages of myogenesis. Therefore, these myogenic regulatory proteins could be considered as sensitive and specific markers for rhabdomyosarcoma. In this report we investigated the immunohistochemical reactivities of myogenin and MyoD in two canine bladder botryoid rhabdomyosarcomas that were different in the degree of differentiation. MyoD was stained in the Ki-67 antigen-positive undifferentiated mesenchymal cells, which had proliferative activity similar to myoblasts differentiated from mesoblasts. In contrast, multinucleated neoplastic cells were positive for myogenin and alpha-sarcomeric actin but not for Ki-67 antigen, similar to the myotubes differentiated from myoblastic cells. The expressions of myogenin and MyoD were closely correlated to the histologic features of myogenic neoplastic cells.

Actins↗

PubMed2004

Formation mechanism of nitrifying granules observed in an aerobic upflow fluidized bed (AUFB) reactor.

The influences of trace metals in the wastewater and shear stress by aeration were particularly examined to clarify the formation mechanism of nitrifying granules in an aerobic upflow fluidized bed (AUFB) reactor. It was found that Fe added as a trace element to the inorganic wastewater accumulated at the central part of the nitrifying granules. Another result obtained was that suitable shear stress by moderate aeration (0.07-0.20 L/min/L-bed) promoted granulation. Furthermore, it was successfully demonstrated that pre-aggregation of seed sludge using hematite promoted core formation, leading to rapid production of nitrifying granules. From these results, a nitrifying granulation mechanism is proposed: 1) as a first step, nitrifying bacteria aggregate along with Fe precipitation, and then the cores of granules are formed; 2) as a second step, the aggregates grow to be spherical or elliptical in form due to multiplication of the nitrifying bacteria and moderate shear stress in the reactor, and then mature nitrifying granules are produced. Fluorescence in situ hybridization (FISH) analysis successfully visualized the change in the spatial distribution of nitrifying bacteria in the granules, which supports the proposed granulation mechanism.

Bacteria↗

PubMed2004

Enhancement of biofilm formation onto surface-modified hollow-fiber membranes and its application to a membrane-aerated biofilm reactor.

Surface-modified hollow-fiber membranes were prepared by radiation-induced grafting of an epoxy-group-containing monomer, glycidylmethacrylate (GMA), onto a polyethylene-based fiber (PE-fiber). The epoxy ring of GMA was opened by introduction of diethylamine (DEA). The bacterial adhesivity to this material (DEA-fiber) was tested by immersion into a nitrifying bacterial suspension. The initial adhesion rates and the amount of attached bacteria of the DEA-fiber were 6-10-fold and 3-fold greater than those of the PE fiber, respectively. A membrane-aerated biofilm reactor (MABR) composed of DEA fibers was developed for partial nitrification with nitrite accumulation. Prior to the nitrification test, it was confirmed that the oxygen supply rate (OSR) was proportional to air pressure up to 100 kPa, allowing easy control of oxygen supply. Stable nitrite accumulation was observed in the partial nitrification test at a fixed oxygen supply throughout the operation period, indicating that oxygen was consumed only by ammonia oxidizers. Furthermore, it was demonstrated that oxygen utilization efficiency (OUE) in the ammonia oxidation process was nearly 100% after 300 h incubation.

Ammonia↗

PubMed2004

Transition of bacterial spatial organization in a biofilm monitored by FISH and subsequent image analysis.

The dynamic transition of bacterial community structure in a biofilm was monitored by the fluorescence in situ hybridization (FISH) technique and subsequent image analysis. Heterotrophic bacteria that had occupied the outer layer were gradually decreased whereas ammonia-oxidizing bacteria (AOB) gradually increased their growth activity and extended their existence area to the outer layer of the biofilm through the gradual reduction of the C/N ratio. The spatial organization of AOB in the biofilm dynamically changed responding to the environmental conditions such as pH fluctuation and lack of dissolved oxygen (DO) and had great influence on the nitrification activity. The accumulation of nitrite was observed at lower DO concentration, which might be due to the property that nitrite-oxidizing bacteria (NOB) possess of higher Km values for oxygen than AOB.

Bacteria↗

PubMed2003

Experimental infection of equine herpesvirus 9 in dogs.

Equine herpesvirus 9 (EHV-9), a new neurotropic equine herpesvirus, was inoculated intranasally at 107 plaque-forming units in five dogs to assess its pathogenicity. Dogs showed weight loss, pyrexia, anorexia, and neurologic signs on the fourth day. The EHV-9 virus was recovered from the examined brains. Histologically, dogs had a fulminant nonsuppurative encephalitis characterized by severe neuronal degeneration and loss, with intranuclear inclusions, slight glial reactions, perivascular cuffing, and multifocal hemorrhage. The olfactory bulb and the frontal and temporal lobes were predominantly affected. Immunohistochemistry revealed reactivity for EHV-9 antigen in neurons. All dogs had mild bronchopneumonia and various degrees of lymphoid necrosis. These findings indicate that dogs are fully susceptible to EHV-9 and that EHV-9 can cause fulminant encephalitis with high mortality in dogs, as in gazelles and goats.

Animals↗

PubMed2003

Comparison of detection specificity of nitrifying bacteria in biofilm using fluorescence in situ hybridization and in situ fluorescent antibody methods.

The in situ fluorescent antibody and fluorescence in situ hybridization (FISH) methods are very useful in the in situ detection of specific bacteria like nitrifiers in a biofilm. In this study, simultaneous staining using the FISH and in situ fluorescent antibody methods was examined. As a result, no specific fluorescence was observed with either method when FISH was performed followed by the in situ fluorescent antibody method; however, when the in situ fluorescent antibody method was performed first followed by FISH, specific fluorescence was observed in both cases. Moreover, it was suggested that the detection specificities of FISH and the in situ fluorescent antibody method are almost identical.

Antibodies, Monoclonal↗

PubMed2003

Degradation of xenobiotic substances using sulfate-reducing bacteria in a UASB reactor.

An upflow anaerobic sludge blanket (UASB) reactor was successfully applied to continuous degradation of ferric ethylene diamine tetraacetate (Fe-EDTA) as a typical xenobiotic substance contained in photo-processing wastewater. The sludge in the UASB reactor had an abundance of sulfate-reducing bacteria (SRB), which had been anaerobically cultivated in a sulfate-rich culture medium including Fe-EDTA and yeast-extract as the carbon sources. Since the prominent reductions of Fe-EDTA and sulfate ion were observed, the contribution of SRB to Fe-EDTA degradation in the UASB reactor was confirmed. The aggregated sludge in the UASB reactor became gradually large reaching steady state with an equivalent diameter of 60-90 microm after 124 days operation. An increase of the amount of yeast extract addition to feed solution improved the Fe-EDTA removal efficiency up to 90%. Moreover, the combination of ozone treatment with SRB treatment further improved removal efficiency of total organic carbon (TOC) in an actual photo-processing wastewater composed of fixing and developing wastes.

Bacteria↗