PubMed Health⌕ Search

Biomedical subjects

H Nagaoka

Publications and source records attributed to H Nagaoka.

At least 19 recordsLinked to original sources
PubMed2006

Effect of bubble flow velocity on drag-force and shear stress working on submerged hollow fibre membrane.

This study is aimed at elucidating the mechanism by which rising air bubbles induce shear stress on hollow fibre membrane surfaces. Shear stress on hollow fibre membrane surfaces (laterally-set and vertically-set) caused by aeration was measured directly using a two-direction load sensor. In the laterally-set hollow fibre module, time-averaged upward-direction shear stress on the membrane surface was compared to theoretical shear stress values considering the effect of water flow on membrane surface. Measured time-average shear stress values were almost 200 times larger than theoretical values implying strong interactions between bubbles and solid surface. In the vertically-set membrane module, velocity measurement of bubble flow using laser Doppler velocimeter revealed that drag force working on membrane surface was closely related to upward-direction water velocity. Also fluctuation of drag force and shear force on membrane surface was found to be related to velocity fluctuation (turbulence).

Bioreactors↗
PubMed2005

Package plant of extended aeration membrane bioreactors: a study on aeration intensity and biofouling control.

Biofouling control is important for effective process of membrane bioreactor (MBR). In this study, phenomena of biofouling for immersed type extended aeration MBR with two different anti-fouling aeration intensities were studied through a laboratory set up. The objectives of this study were (a) to observe biofouling phenomena of MBR that operates under different anti-fouling bubbling intensity, and simultaneously monitors performance of the MBR in organic carbon and nutrients removal; (b) to compare effectiveness of detergent and detergent-enzyme cleaning solutions in recovering biofouled membranes that operated in the extended aeration MBR. For MBR, which operated under continuous anti-fouling aeration, deposition and accumulation of suspended biomass on membrane surface were prohibited. However, flux loss was inescapable that biofilm layer was the main problem. Membrane cleaning was successfully carried out with detergent-enzyme mixture solutions and its effectiveness was compared with result from cleaning with just detergent solution.

Biofilms↗
PubMed2005

Influence of extracellular polymeric substances on nitrogen removal in an intermittently-aerated membrane bioreactor.

Influence of EPS on fouling of intermittent aeration MBR reactor (denitrification MBR) was investigated changing intermittent aeration cycle (10 minute-cycle and 120 minute-cycle) in laboratory-scale reactors using synthetic wastewater. EPS were extracted from bacterial cells using cation resin method and molecular weight fractioning of EPS was conducted using gel chromatography. In both of the reactors, nitrogen removal rate was almost 100% after 50th day although DO concentration was not very high during the aerated phase because of accumulation of nitrifying bacteria in the reactors. In the 120 minutes-cycle reactor, trans-membrane pressure increased more rapidly than in the 10 minutes-cycle reactor. The reason might be that EPS of more than 1000 kDa, which are the main fouling substances, are produced more rapidly in the 120 minute-cycle condition. It was also found that three peaks at around 100 kDa, 500 kDa and 2000 kDa are prominent in EPS in intermittent-aeration MBR irrespective of cycle and higher molecular weight EPS are decomposed to smaller molecular weight EPS on membrane surface.

Aerobiosis↗
PubMed2002

Effect of loading rate and intermittent aeration cycle on nitrogen removal in membrane separation activated sludge process.

The performance of the submerged membrane separation activated sludge process with intermittent aeration was investigated in a laboratory scale experiment by changing organic loading rate and intermittent aeration cycle. A rectangular PVC tank was used as an aeration tank, in which a flat-sheet type Micro-Filtration membrane made of poly-olefin with a pore size of 0.2 microm was submerged. Organic loading rate to the reactor was set at 0.3 and 0.8 g-TOC/L/day. C/N ratio in the feed was set at around 5.0 for every condition. Aeration cycle was changed from 10 min-10 min (aeration-stop) to 120 min-120 min in different organic loading conditions. Flux through the membrane was set at 0.25 m/day. Membrane fouling proceeded rapidly in 0.8 g-TOC/L/day conditions. However, when organic loading rate was 0.3 g-TOC/L/day, bacterial metabolic substances were degraded rapidly compared to the production, thereby decreasing viscosity in mixed liquor. Nitrogen removal rate was between 60% and 80% for 0.8 g-TOC/L/day loading, and between 50% and 65% for 0.3 g-TOC/L/day loading. And the nitrogen removal was highest in 40 min to 60 min aeration cycle conditions. Too short aeration cycle did not result in sufficiently long anoxic periods for denitrification while too long a cycle resulted in unnecessary anaerobic periods after depletion of nitrate. Intermittent aeration was effective also for decreasing viscosity in mixed liquor.

Bioreactors↗
PubMed2002

Comparative study on microbial removal in immersed membrane filtration (IMF) with and without powdered activated carbon (PAC).

This paper describes an investigation on the effect of microbial removal using IMF for high quality drinking water production. The comparison of IMF and IMF-PAC configuration was carried out in the study to highlight the importance of PAC in the system. The specific objective of this study was to study the effect of PAC adsorption in the IMF-PAC system particularly in removing microbial substances from contaminated raw water. A bench scale IMF-PAC configuration using a flat sheet microfiltration membrane was set up for experimental purposes. Experimentally, the result has shown high removal of microbial substances with the IMF-PAC system compared to IMF. The result of E. coli removal achieved was below the detectable level due to the microbial size, which is bigger than membrane pore size. The addition of PAC has shown a direct effect on total microbial removal. The adsorption of microbial onto PAC surfaces reduced the amount of smaller microbial present in permeate samples. As a conclusion, the configuration of IMF is a promising separation process in removing microbial substances, especially when the system is combined with PAC.

Adsorption↗
PubMed2002

Performance of an extended aeration-microfiltration (EAM) reactor in treating high strength industrial wastewater.

A laboratory study was conducted on an Extended Aeration-Microfiltration (EAM) reactor in treating a food industry wastewater. The reactor contained horizontally laid hollow fibre microfiltration (MF) units that were fully submerged. The MF units were connected to a peristaltic pump that was used to extract permeate continuously under suction pressure. Continuous aeration from beneath the modules provided the crossflow effect to the MF units. Active activated sludge was used in the start-up where the sludge was mixed together with the feed water at a Food/Microorganisms (F/M) value of about 0.1. Primary effluent with Chemical Oxygen Demand (COD) values ranged between 1,500 and 3,000 mg/l was used as feed water. The EAM reactor was operated for nearly three months without initiating cleaning of the MF units. A suction pressure of 0.9 bar and Mixed Liquor Suspended Solids (MLSS) of over 5,500 mg/l were reached when nearing the end of the three month operation period. Permeate COD and turbidity reduction of over 97% and 99% respectively, were achieved. Prior to this, the MF module arrangements were studied; where vertically arranged modules were found to perform poorly as compared to the horizontally laid modules, in terms of clean water permeate flux.

Bioreactors↗
PubMed2001

B cell development is arrested at the immature B cell stage in mice carrying a mutation in the cytoplasmic domain of immunoglobulin beta.

The B cell receptor (BCR) regulates B cell development and function through immunoglobulin (Ig)alpha and Ig beta, a pair of membrane-bound Ig superfamily proteins, each of which contains a single cytoplasmic immunoreceptor tyrosine activation motif (ITAM). To determine the function of Ig beta, we produced mice that carry a deletion of the cytoplasmic domain of Ig beta (Ig beta Delta C mice) and compared them to mice that carry a similar mutation in Ig alpha (MB1 Delta C, herein referred to as Ig alpha Delta C mice). Ig beta Delta C mice differ from Ig alpha Delta C mice in that they show little impairment in early B cell development and they produce immature B cells that respond normally to BCR cross-linking as determined by Ca(2+) flux. However, Ig beta Delta C B cells are arrested at the immature stage of B cell development in the bone marrow and die by apoptosis. We conclude that the cytoplasmic domain Ig beta is required for B cell development beyond the immature B cell stage and that Ig alpha and Ig beta have distinct biologic activities in vivo.

Alleles↗
PubMed2001

Intractable Q fever treated with recombinant gamma interferon.

A 3-year-old boy with Q fever received several kinds of antibiotics including minocycline, but spiking fever and positive PCR of Coxiella burnetii continued for several months. He became asymptomatic and his abnormal laboratory data normalized after the administration of gamma interferon three times a week.

Child, Preschool↗
PubMed2001

[Serological cross-reaction among Bartonella henselae, Chlamydia pneumoniae and Coxiella burnetii by indirect fluorescence antibody method].

We studied the serological cross-reactions among Bartonella henselae, Chlamydia pneumoniae and Coxiella burnetii by indirect fluorescence antibody (IFA) method, using sera from 8 patients with cat scratch disease (CSD), 13 patients with C. pneumoniae infection and 12 patients with acute Q fever. B. henselae IgG antibody was negative in 13 patients with C. pneumoniae infection, and was positive in 3 (titers being 1:64) of 12 patients with Q fever, whereas B. henselae IgM antibody was negative in all the patients with C. pneumoniae infection or Q fever. C. burnetii IgG antibody was removed by absorption of these 3 sera with C. burnetii antigens, whereas B. henselae IgG antibody did not change. C. pneumoniae IgG antibody was positive in 3 (titers being 1:125 in two, 1:32 in one) of 8 patients with CSD. Both C. pneumoniae and B. henselae IgG antibody titers were significantly reduced by absorption of these 3 sera with B. henselae antigens. C. burnetii IgG or IgM antibodies were negative in all patients with CSD. In conclusion, no serological cross-reaction between B. henselae and C. burnetii was observed. On the other hand. B. henselae IgG antibody cross-reacted to C. pneumoniae antigens, whereas C. pneumoniae IgG antibody did not cross-react to B. henselae antigens. Our findings suggest that determination of B. henselae IgG or IgM antibodies were not influenced by C. pneumoniae and C. burnetii antigens.

Bartonella henselae↗
PubMed2001

Resolution and synthesis of optically active alcohols with immobilized ovalbumin and pea protein as new bio-catalysts.

It was found that ovalbumin stereoselectively oxidized one of the enantiomers of p-substituted racemic alcohols, thereby providing optically active alcohols with high optical purities. It was found out that, when used appropriately in combination with immobilized pea protein, immobilized ovalbumin made it possible to resolve and synthesize racemic 1-(2-naphthyl)ethanol, 1-phenylethanol, and 1-phenyl-1-propanol. Immobilized ovalbumin could be continuously recycled at least three times without lowering the yield and purity of the products. These results suggested that cereals, beans, and ovalbumin might have additional fourth function among conventional foods. Namely, there might contain nutritional, sensory, biologically regulatory and bio-catalytic functions in conventional foods.

Alcohols↗
PubMed2001

[A case of extracardiac unruptured aneurysm of sinus of Valsalva with obstruction of the right coronary artery and aortic regurgitation].

A 67-year-old female was admitted to our hospital with heart failure. Echocardiography, chest CT and MRA revealed an unruptured aneurysm of sinus of Valsalva. Cardiac catheterization and angiography detected obstruction of the ostium of the right coronary artery and moderate aortic regurgitation. Operative findings showed an extracardiac unruptured aneurysm arising from the right sinus of Valsalva. The orifice of the aneurysm was closed with Gore-Tex patch, then aortic valve replacement combined with single CABG to RCA was simultaneously performed. The pathological findings strongly suggested its acquired origin.

Aged↗
PubMed2000

Asymmetric synthesis of the core structure of (-)-CP-263,114.

The enantioselective construction of a fully functionalized core structure of (-)-CP-263,114 (1), containing most of the required functionality for total synthesis, was conducted through sequential radical fragmentation-reductive olefination.

Enzyme Inhibitors↗
PubMed2000

Highest microvessel count as a long-term prognostic factor in Japanese breast cancer patients.

The aim of this study was to determine whether microvessel density (MVD) could add useful information in predicting the prognosis of breast cancer patients. In our study, MVD was calculated by counting microvessels per x200 field in the highest neovascularized area of the tumor (highest microvessel count, HMC). HMC significantly increased according to the increased number of positive nodes. Higher HMC significantly correlated with worse relapse-free survival (RFS) of patients with negative node, one to three positive nodes in the axilla or with stage I and II tumors. HMC, however, was not predictive for RFS of patients with four or more positive nodes or with stage III tumors. Multivariate analysis revealed that HMC was second only to nodal status and tumor size as being predictive for RFS. These results suggest that HMC could be used in selection of patients with early-stage breast cancer who are at high risk for having occult metastasis.

Adult↗
PubMed2000

Ras mediates effector pathways responsible for pre-B cell survival, which is essential for the developmental progression to the late pre-B cell stage.

Ras is essential for the transition from early B cell precursors to the pro-B stage, and is considered to be involved in the signal cascade mediated by pre-B cell antigen receptors. To examine the role of p21(ras) in the late stage of B cell differentiation, we established transgenic mice (TG) expressing a dominant-inhibitory mutant of Ha-ras (Asn-17 Ha-ras) in B lineage cells at high levels after the early B cell precursor stage. Expression of p21(Asn-17) (Ha-ras) was associated with a prominent reduction in the number of late pre-B cells, but had little effect on proliferation of early pre-B cells. Inhibition of p21(ras) activity markedly reduced the life span of pre-B cells, due, at least in part, to downregulation of the expression of an antiapoptotic protein, Bcl-xL. Thus, the apparent role for p21(ras) activity in pre-B cell survival may explain the decreased numbers of late pre-B cells in Asn-17 Ha-ras TG. Consistent with this possibility, overexpression of Bcl-2 in Asn-17 Ha-ras TG reversed the reduction in the number of late pre-B cells undergoing immunoglobulin light chain gene (IgL) rearrangement and progressing to immature B cells. These results suggest that p21(ras) mediates effector pathways responsible for pre-B cell survival, which is essential for progression to the late pre-B and immature B stages.

Animals↗
PubMed2000

Immunization and infection change the number of recombination activating gene (RAG)-expressing B cells in the periphery by altering immature lymphocyte production.

Recombination activating gene (RAG) expression in peripheral B cells increases after immunization with (4-hydroxy-3-nitrophenyl) acetyl coupled to chicken gamma globulin (NP-CGG) in alum. This increase could result from reinduction of RAG expression or, alternatively, from accumulation of RAG-expressing immature B cells in the periphery. We have used mice that carry a green fluorescent protein (GFP) RAG indicator transgene (RAG2-GFP) to characterize the RAG-expressing B cells in immunized spleens. Most of the RAG2-GFP-expressing B cells in unimmunized spleen are immature B cells. Injection with NP-CGG in alum initially suppresses lymphopoiesis in the bone marrow and decreases the number of immature RAG2-GFP-expressing B cells in the spleen. Recovery of lymphopoiesis in the bone marrow coincides with accumulation of RAG-expressing immature B cells in the spleen. Most of the RAG-expressing cells that accumulate in the spleen after immunization do not proliferate and they are not germinal center cells. Neither the initial suppression of lymphopoiesis nor the subsequent accumulation of RAG-expressing cells in the spleen is antigen dependent, since similar changes are seen with alum alone. Furthermore, such changes in the numbers of developing and circulating immature lymphoid cells are seen after injection with complete Freund's adjuvant or malaria infection. Our experiments suggest that adjuvants and infectious agents cause previously unappreciated alterations in lymphopoiesis resulting in the accumulation of RAG-expressing immature B cells in the spleen.

Adjuvants, Immunologic↗
PubMed2000

Sudden hemorrhage of the breast caused by breast cancer: a case report and review of the literature.

A rare case of sudden hemorrhage caused by breast cancer is reported. A 71-year-old woman noted bleeding from her left breast. Physical examination of the left breast showed a localized open cavity accompanied by bleeding and coagulation. The patient had no history of breast trauma or anticoagulation therapy. Incisional biopsy followed by histological examination resulted in a diagnosis of granulation tissue with no cancer cells present. Mammography and ultrasonography indicated probable breast cancer. As a result, a second incisional biopsy was performed, which suggested invasive ductal carcinoma without histological skin invasion. A modified radical mastectomy was performed under a diagnosis of stage II breast cancer. Breast cancer with sudden hemorrhage is rare. We review the literature and discuss the cause of this unusual manifestation.

Aged↗
PubMed2000

Regulation of RAG expression in developing lymphocytes.

Proper expression of products of the recombination-activating genes (RAGs) is essential for the development of the adaptive immune system. A major advance in the past year toward understanding RAG regulation is the establishment of green fluorescent protein (GFP)-RAG indicator mouse strains. In vivo visualization of RAG expression in single cells has helped to define the cells that express RAGs in secondary lymphoid organs and revealed differential cis requirements for stage- and lineage-specific RAG expression.

Animals↗