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Biomedical subjects

Hiroyuki Nakamura

Publications and source records attributed to Hiroyuki Nakamura.

At least 91 records · Page 5Linked to original sources
PubMed2004

Platelet-derived growth factor plays a critical role to convert bone marrow cells into glomerular mesangial-like cells.

BACKGROUND: Despite increasing interest in bone marrow-derived stem cells, little is known about critical factors that determine their fates both in vitro and in vivo. Recently, we have reported that bone marrow is a reservoir for glomerular mesangial cells in rats. To find a key factor responsible for the differentiation of bone marrow-derived cells into mesangial cells, we established a new culture system of rat bone marrow, which is based on serial replating and differential attachment to collagen types I and IV. METHODS: Bone marrow cells that did not adhere to collagen type I within 24 hours were transferred to collagen type IV-coated dishes. Then, the cells attached to collagen type IV in the following 24 hours were maintained in the presence of 2% horse serum, 200 ng/mL of platelet-derived growth factor (PDGF)-BB, and 1 micromol/L of all-trans retinoic acid. In vivo effect of PDGF-B was also examined by introducing human PDGF-B gene into glomeruli. RESULTS: After cultivation under the above condition for 7 days, approximately 14% of cells expressed Thy-1 and desmin, both of which are markers for rat mesangial cells. Thy-1++/desmin+ cells were stellate-shaped, and contracted in response to angiotensin II. When human PDGF-B gene was overexpressed in the glomeruli of chimeric rats whose bone marrow was transplanted from enhanced green florescent protein (EGFP) transgenic rats, the number of EGFP+ mesangial cells increased. This effect was canceled by prior introduction of a neutralizing molecule that is composed of PDGF receptor-beta ligand binding site and IgG-Fc. CONCLUSION: These results indicate that PDGF-B plays a critical role to direct bone marrow-derived cells toward mesangial-like cells both in vitro and in vivo.

Angiotensin II↗
PubMed2004

DNAzyme for TGF-beta suppressed extracellular matrix accumulation in experimental glomerulonephritis.

BACKGROUND: We developed an electroporation-mediated gene transfer method targeting glomerular mesangial cells. Injecting DNA solution via renal artery followed by electric pulses using tweezers-type electrodes could result in efficient transfection in mesangial cells. Therefore, this gene transfer system opened a feasible strategy to manipulate the function of several cytokines and growth factors in mesangial cells. Recently, a new generation of catalytic nucleic acid composed of DNA, named DNA enzyme (DNAzyme), has been developed. METHOD: We generated a DNAzyme (TGFDE) targeting transforming growth factor-beta1 (TGF-beta1), and examined the therapeutic effect of TGFDE in vitro and in vivo. RESULTS: In cultured rat mesangial cells, treatment with TGFDE blocked TGF-beta1 mRNA expression, and thereby suppressed type I collagen mRNA expression. Next, we introduced TGFDE or scrambled DNAzyme (TGFSCR) into anti-Thy-1 model of nephritic rats by electroporation 3 days after disease induction. Northern blot analysis and immunohistochemical staining demonstrated that glomerular message and protein expression of TGF-beta1, alpha-smooth muscle actin (alpha-SMA), and type I collagen were suppressed in TGFDE-transfected nephritic rats compared with untreated nephritic rats and TGFSCR-transfected rats on day 7. Consequently, we observed significant reduction in glomerular matrix score in TGFDE-transfected nephritic rats. CONCLUSION: Inhibition of TGF-beta1 expression by electroporation-mediated DNAzyme transfer might be useful for the therapy of glomerulonephritis.

Actins↗
PubMed2004

Kaposi's sarcoma-associated herpesvirus K7 protein targets a ubiquitin-like/ubiquitin-associated domain-containing protein to promote protein degradation.

Pathogens exploit host machinery to establish an environment that favors their propagation. Because of their pivotal roles in cellular physiology, protein degradation pathways are common targets for viral proteins. Protein-linking integrin-associated protein and cytoskeleton 1 (PLIC1), also called ubiquilin, contains an amino-terminal ubiquitin-like (UBL) domain and a carboxy-terminal ubiquitin-associated (UBA) domain. PLIC1 is proposed to function as a regulator of the ubiquitination complex and proteasome machinery. Kaposi's sarcoma-associated herpesvirus (KSHV) contains a small membrane protein, K7, that protects cells from apoptosis induced by various stimuli. We report here that cellular PLIC1 is a K7-interacting protein and that the central hydrophobic region of K7 and the carboxy-terminal UBA domain of PLIC1 are responsible for their interaction. Cellular PLIC1 formed a dimer and bound efficiently to polyubiquitinated proteins through its carboxy-terminal UBA domain, and this activity correlated with its ability to stabilize cellular I kappa B protein. In contrast, K7 interaction prevented PLIC1 from forming a dimer and binding to polyubiquitinated proteins, leading to the rapid degradation of I kappa B. Furthermore, K7 expression promoted efficient degradation of the p53 tumor suppressor, resulting in inhibition of p53-mediated apoptosis. These results indicate that KSHV K7 targets a regulator of the ubiquitin- and proteasome-mediated degradation machinery to deregulate cellular protein turnover, which potentially provides a favorable environment for viral reproduction.

Adaptor Proteins, Signal Transducing↗
PubMed2004

Physiological involvement of placental endothelin-1 and prostaglandin F2alpha in uteroplacental circulatory disturbance in pregnant rats exposed to heat stress.

Several studies suggest that heat stress affects placental functions including uteroplacental circulation, subsequently leading to pregnancy failure and birth weight reduction. To clarify the involvement of endothelin and placental prostaglandin (PG) systems in the uteroplacental circulation during heat stress, we examined the effects of i.v. administration of the endothelin receptor antagonist bosentan and the cyclooxygenase inhibitor indomethacin on uteroplacental blood flow and on placental PGE2 and PGF2alpha levels and their 13,14-dyhydro-15-keto-metabolites (PGEM and PGFM, respectively) in heat-exposed or non-heat-exposed pregnant rats. The administration of bosentan or indomethacin did not change uteroplacental blood flow in non-heat-exposed pregnant rats. In contrast, heat reduced uteroplacental blood flow in pregnant rats, but the reduction was reversed by the administration of bosentan or indomethacin before heat exposure. Heat did not change placental PGE2 or PGEM levels, but in pregnant rats it increased placental PGF2alpha and PGFM levels, which were reversed by bosentan or indomethacin. Our results suggest that the activation of placental endothelin receptor and PGF2alpha systems are involved in the uteroplacental circulatory disturbances produced by heat. PGF2alpha systems activated by heat may be involved in the vasoconstricting effects of endothelin-A and -B receptors during heat exposure.

Animals↗
PubMed2004

Middle ear pressure in patients with dizziness.

The middle ear pressure was analyzed in 112 patients with dizziness. In 37 patients with Meniere's disease, the middle ear pressure on the low-pressure side was significantly lower, the middle ear pressure difference (between the high and low sides) was significantly larger, and the maximum compliance on the low-compliance side was significantly lower than in normal volunteers. The middle ear pressure difference was significantly larger during periods of dizziness or recurrent dizziness than at the time of remission. In patients with Meniere's disease, a middle ear pressure difference of more than 50 decapascals was significantly more common among those with abnormal blood gas levels than among those with normal blood gas levels. In 27 patients with cervical vertigo and 15 patients with vertebrobasilar insufficiency, the middle ear pressure difference was also significantly larger than in normal volunteers. These results suggest that the middle ear pressure difference might be closely related to dizziness in Meniere's disease and less closely related in cervical vertigo or vertebrobasilar insufficiency. The middle ear pressure difference might also be related to abnormal blood gas levels in patients with dizziness.

Acoustic Impedance Tests↗
PubMed2004

Abnormalities of p51, p53, FLT3 and N-ras genes and their prognostic value in relapsed acute myeloid leukemia.

To clarify the role of the genetic mutations in the clinical course of acute myeloid leukemias (AML), we analyzed for p51, p53, FLT3 and N-ras gene mutations and the expression of the p51 gene in relapsed AML. Paired samples obtained from patients with AML at both stages of diagnosis and first relapse were analyzed. Twenty-four patients with relapsed AML survived for 6 to 81 months (median 24 months) from diagnosis. In one patient, no point mutation of the p51 gene was detected, but loss of the p51 gene expression was observed at both stages. Point mutations of the p53 gene were positive at both stages (+/+) in two patients and negative at diagnosis and positive at relapse (-/+) in two patients. Tandem duplication of the FLT3 gene was detected in five patients at both stages (+/+). N-ras gene mutations at both stages (+/+) were detected in three patients. Mutant p53 at relapse was associated with short survival in patients with relapsed AML (P<0.014). Our findings show that p53 mutations were, at least in part, associated with the mechanism of relapse in AML, while new p51, FLT3 and N-ras gene alterations did not occur at relapse. Loss of the p51 gene expression in de novo AML has not been reported yet.

Adult↗
PubMed2004

Primary seminoma in the middle mediastinum.

Primary mediastinal seminoma is a relatively rare tumor usually located in the anterior mediastinum. We report here an extremely rare case of a 66-year-old man with primary seminoma in the middle mediastinum. A physical examination showed lymphadenopathy in the right supraclavicular area. A chest CT confirmed the presence of a tumor occupying the retrotracheal space. A histological examination demonstrated metastatic seminoma from the open biopsy of the lymph node. Abdominal, pelvis, and cerebral CT scan and testicular ultrasound were negative. Thus, primary mediastinal seminoma in the middle mediastinum with supraclavicular lymph node metastasis was diagnosed.

Aged↗
PubMed2004

Subacute cor pulmonale due to tumor embolism.

We describe a patient wih subacute cor pulmonale caused by tumor emboli in the lungs. A 64-year-old female suffering from a subacute progressive cough and shortness of breathing died of severe pulmonary hypertension seven days after admission. Neither chest CT scans nor lung perfusion scintigraphy showed any abnormal findings. Microscopic examination after an autopsy revealed diffuse intravascular tumor emboli occluding not only the small pulmonary arteries and arterioles, but also the lymphatic vessels, which were suggested to be metastases of a breast carcinoma resected five years previously. Thus, pulmonary tumor embolism should be considered in the differential diagnosis of primary pulmonary hypertension, particularly in patients with a past history of cancers.

Autopsy↗
PubMed2004

[Lymphangioleiomyomatosis (LAM) causing chylothorax].

A 28-year-old woman was admitted to our hospital complaining of chest pain and dyspnea. Chest radiographs showed left pleural effusion. The effused fluid obtained by thoracocentesis was milky, and so chylothorax was diagnosed. A high-resolution chest CT (HRCT) scan demonstrated diffuse multiple cystic lesions, which were undetectable by conventional CT. An abdominal CT scan showed a retroperitoneal tumor. Since the effusion was resistant to conservative therapy, we performed clipping of the thoracic duct under the diaphragm. Since the effusion disappeared after continuous aspiration, 10 KE of OK-432 was administered into the pleural cavity, and the chylorrhea disappeared. The clinical diagnosis, based on the biopsy of the abdominal tumor, was lymphangioleiomyomatosis. Chylothorax developing from lymphangioleiomyomatosis is rare in Japan. However, we must consider the possibility of lymphangioleiomyomatosis in patients with chylothorax, and always perform chest HRCT.

Adult↗
PubMed2003

Projections from the cytochrome oxidase modules of visual area V2 to the ventral posterior area in the macaque.

The ventral part of the third visual cortical complex, the ventral posterior area (VP) or V3v, is located between the ventral half of visual areas V2 and V4. Because of its location and the physiological properties of its neurons, VP has been considered to be involved in the ventral stream visual areas. The ventral stream visual areas such as V4 and TEO receive projections from the cytochrome oxidase (CO)-rich thin stripes and CO-poor interstripe regions of V2; however, which CO-modules project to VP remains unclear. Moreover, it is not clear whether V1 projects to VP. We injected retrograde tracers into VP and found that VP receives projections from V2 neurons not only in the CO-rich thin stripes and CO-poor interstripe regions but also in the CO-rich thick stripes. We also confirmed the virtual absence of inputs from V1 to VP. These results support the hypothesis that VP constitutes a distinct extrastriate visual area and also suggest that, in addition to color and shape information, VP may also process visual information related to space and disparity.

Animals↗
PubMed2003

Continuous synthesis of CdSe-ZnS composite nanoparticles in a microfluidic reactor.

ZnS-coated CdSe composite particles have been continuously synthesized in a microfluidic reactor. By using this system, CdSe particles and a ZnS coating can be produced in sequence, and the particle size and layer thickness can be directly adjusted by the residence time. It demonstrated that the continuous synthesis in the microreactor was a simple and efficient way to prepare composite particles with different structures and determine the optimized experimental conditions.

Journal Article↗
PubMed2003

Sequence-selective DNA detection using multiple laminar streams: a novel microfluidic analysis method.

On-site detection methods for DNA have been demanded in the pathophysiology field. Such analysis requires a simple and accurate method, rather than high-throughput. This report describes a novel microfluidic analysis method and its application for simple sequence-selective DNA detection. The method uses a microchannel device with a serpentine structure. Sequence-specific binding of probe DNA can be detected at one side of the microchannel. This method is capable of sequence-specific detection of DNA with high accuracy. Single base mutations can also be analyzed. Combination of laminar stream and laminar secondary flow in the microchannel enable specific detection of probe-bound DNA.

Base Sequence↗
PubMed2003

Monoclonal antibodies with defined recognition sequences in the stem region of CD44: detection of differential glycosylation of CD44 between tumor and stromal cells in tissue.

CD44 is an enigmatic cell adhesion molecule acting as a major receptor for hyaluronan and playing roles in many biological and pathological processes such as lymphocyte homing, T-cell activation, wound healing, angiogenesis, and metastatic spread of tumor cells. However, the complexity of the molecule, with its alternatively spliced variants, extensive glycosylation, and processing by different proteases, has hampered detailed analysis. In this study, we prepared four monoclonal antibodies (285-2F12, 284-43F1, 268-1F5, and 294-6F2) and one polyclonal antibody (C6) that recognize defined sequences in the stem region of CD44H. Interestingly, two of the monoclonal antibodies, 268-1F5 and 294-6F2, failed to recognize the CD44 expressed in five of the seven human tumor cell lines examined by Western blotting. Treatment of the samples with a combination of neuraminidase and O-glycosidase as well as the expression of mutants with site-directed mutations at possible modification sites rendered the CD44 reactive to the antibodies. Thus, the reactivity of the antibodies is sensitive to O-glycosylation presumably near the recognition sites. Glycosylation of CD44 that affects reactivity to the antibodies was found to be regulated differentially between tumor and stromal cells in two breast and three oral carcinoma tissues. Antibody 268-1F5 reacted to the tumor cells, but not to the cells in the surrounding stroma. On the other hand, the reactivity of 294-6F2 to the cells was opposite between the two tumor types. Thus, these sets of antibodies are useful to detect and analyze the as-yet-unknown roles of site-specific glycosylation of CD44, particularly in tumors.

Amino Acid Sequence↗
PubMed2003

Preparation and characterization of nanoaggregates of poly(ethylene oxide)-b-polymethacrylate and poly-L-lysine.

Poly(ethylene oxide)-b-polymethacrylate (PEO-b-PMA), one of the double-hydrophilic block copolymers, has proved to the form nanoaggregates with poly-L-lysine (PLS). This was confirmed by turbidimetry, zeta-potential measurements, and dynamic light scattering. The nanoaggregate formation is induced by electrostatic charge neutralization of the PMA block with PLS. The properties of the aggregates are affected by PLS concentration as well PEO-b-PMA concentration. The aggregates have potential applications in biomedical science.

Ethylene Oxide↗
PubMed2003

Modified micro-space using self-organized nanoparticles for reduction of methylene blue.

By using silica layers bound to the surface of the inner wall of the microchannel via a self-assembly technique which relies on capillary forces to organize the colloids, TiO2 particles were attached to the inner surface of a microcapillary. The reduction rate of methylene blue increased by more than 150 times in the SiO2/TiO2 modified micro-space compared to that in a batch system.

Journal Article↗
PubMed2003

Hemophagocytic syndrome in ileum-origin B-cell lymphoma.

A 56 year-old-man was admitted due to upper abdominal tumor and was diagnosed as having stage IVb diffuse B-cell malignant lymphoma that originally developed in the terminal ileum. The first and the second administrations of CHOP (cyclophosphamide, 750 mg/m(2); adriamycin, 50 mg/m(2); vincristine, 1.4 mg/m(2); and prednisolone, 100 mg/day) therapy were effective; however, the third course of therapy was postponed because of an episode of massive hematochezia. After this episode, lymph nodes began to enlarge and progressive pancytopenia occurred. Bone marrow smear showed the proliferation of reactive histiocytic cells which phagocytized red blood cells, white blood cells, and platelets. B-cell lymphoma-associated hemophagocytic syndrome (B-LAHS) was diagnosed. This case is extremely rare because: (1) LAHS occurred in an ileum-origin B-cell lymphoma, and (2) LAHS developed during an interval after chemotherapy.

Antibiotics, Antineoplastic↗