Biomedical subjects

M Okumura

Publications and source records attributed to M Okumura.

At least 19 recordsLinked to original sources

PubMed2006

Inclusion of the transcervical approach in video-assisted thoracoscopic extended thymectomy (VATET) for myasthenia gravis: a prospective trial.

BACKGROUND: Because evidence-based data regarding the quality of video-assisted thoracoscopic thymectomy for the treatment of myasthenia gravis are lacking, a prospective trial comparing three different operative approaches was conducted to evaluate their efficacy. METHODS: This prospective study enrolled 20 consecutive patients with nonthymomatous myasthenia gravis. A series of three approaches for bilateral video-assisted thoracoscopic extended thymectomy (VATET) using the anterior chest wall-lifting method (original), the original method with a flexed-neck position (modified), and the original method with a transcervical approach (final) were prospectively performed in each patient for quantitative and pathologic evaluation of the residual thymus after each approach. RESULTS: Complete VATET required 242 +/- 48 min, with the transcervical procedure requiring 23 +/- 12 min. After the modified method, the residual thymus in the cervical region was 1.5 cm in size and weighed 0.8 g (0.8% of the entire thymus), as compared with a size of 2.2 cm and a weight of 1.3 g (3.2%) after the original method. Each value is the result of comparison with the final method. Histopathologic studies showed residual tissue in the germinal center as well as Hassall's corpuscles in more than 70% of cases. CONCLUSION: The findings show that VATET without the transcervical approach could be an immunologically incomplete treatment for myasthenia gravis. Therefore, the transcervical approach should be included in VATET procedures to ensure radicality.

Adult↗

PubMed2006

Decrease in tetrahydrobiopterin as a possible cause of nephropathy in type II diabetic rats.

A decrease in renal synthesis of nitric oxide (NO) in the progression of diabetic nephropathy has been documented. As (6R)-5,6,7,8-tetrahydrobiopterin (BH4) is an essential cofactor of NO synthase, we investigated whether BH4 deficiency is involved in the pathogenesis of nephropathy. Ten-week-old Otsuka Long-Evans Tokushima Fatty (OLETF) rats were used as a type II diabetic model, and Long-Evans Tokushima Otsuka (LETO) rats as the healthy controls. OLETF rats were orally treated with BH4 (10 mg/kg daily) or with water from 10 to 61 weeks of age. In another experiment, OLETF rats were treated orally with a calcium channel blocker, benidipine (5 mg/kg daily), or with 0.3% carboxymethyl cellulose (nontreated) from 10 to 52 weeks of age. Proteinuria was observed periodically, and at the end of the study, BH4 level and GTP cyclohydrolase I (GTPCH) activity in the kidney were measured. Proteinuria was observed at 13 weeks of age in the OLETF rats, and deteriorated until 61 weeks of age. Supplemental BH4 reduced the proteinuria. At 52 weeks of age, GTPCH activity and the BH4 level were decreased in the plasma and kidneys of OLETF rats, whereas they were significantly higher in the benidipine group than in the nontreated group. Proteinuria was milder in the benidipine group than in the nontreated group, without a concomitant decrease in blood pressure. Histologically observed glomerulosclerosis was mild in the BH4 and benidipine groups. In type II diabetic rats, renal BH4 is considered to play a crucial role in the pathogenesis of diabetic nephropathy. Benidipine was found to preserve BH4 levels, suggesting therapeutic renoprotective effects.

Animals↗

PubMed2006

Safer video-assisted thoracoscopic thymectomy after location of thymic veins with multidetector computed tomography.

BACKGROUND: Video-assisted thoracoscopic (VATS) thymectomy has been applied as a surgical option for autoimmune myasthenia gravis. Prior identification and fine division of the thymic veins are critical to the prevention of unexpected severe bleeding that may require conversion to open surgery. Until recently, such bleeding could be avoided only by meticulous dissection of thymic fat tissue away from the left brachiocephalic vein (LBV). With recent advances in computed tomography (CT), multidetector-row computed tomography (MDCT) can readily be obtained and provides three-dimensional (3D) images. This study explored its value for preoperative identification of the thymic veins draining into the LBV, and thus for prevention of injury to these veins during endoscopic thymectomy. METHODS: Five patients with myasthenia gravis, thymoma, or both underwent enhanced MDCT preoperatively. The thymic veins draining into the LBV were visualized using both horizontal and sagittal/coronal CT images. Then 3D images were reconstructed to enable operators to simulate endoscopic views. During each VATS extended thymectomy, the numbers and branching patterns of the thymic veins were compared with the preoperative MDCT images. RESULTS: The thymic veins draining into the LBV were clearly identified with MDCT in all five patients examined. Reconstructed 3D images clearly located their courses in the thymic/fat tissue and their entry routes into the LBV, thus simulating the actual intraoperative endoscopic views. All tributaries divided during surgery were identified preoperatively with MDCT. CONCLUSIONS: Location of thymic veins with MDCT can provide precise preoperative information about thymic venous anatomy. This easy and less invasive examination has the potential to make VATS thymectomy easier and safer.

Adult↗

PubMed2006

Clinical pharmacokinetics of anti-angiogenic photodynamic therapy with benzoporphyrin derivative monoacid ring-A in dogs having naturally occurring neoplasms.

The aim of this study was to examine the pharmacokinetics of clinically applied benzoporphyrin derivative monoacid ring-A (BPD-MA; Verteporfin), a second-generation photosensitizer, during a trial of photodynamic therapy (PDT) in nine dogs having naturally occurring neoplasms. After injecting BPD-MA at 0.5 mg/kg intravenously, its mean half-life (t1/2) was found to be 8.14 +/- 5.34 h, mean clearance (Cl) 35.13 +/- 9.62 ml/(h kg), the mean value of the volume of distribution (Vc) 0.08 +/- 0.01 l/kg and the mean steady state volume of distribution (Vss) 0.38 +/- 0.31 l/kg respectively. With the exception of a transitional increase in serum alkaline phosphatase activity, no other clinical abnormalities were observed. The t1/2 in dogs with naturally occurring tumours was longer than that in humans, but similar to that in rats. The values of Cl and Vss in dogs having naturally occurring neoplasms were lower than those in humans. It is suggested that the pharmacokinetics of BPD-MA in tumour-bearing dogs would be helpful in determining the protocol of a short drug-light interval PDT with BPD-MA that mainly targets the tumour vasculature.

Animals↗

PubMed2006

Autologous transplantation of adipose tissue-derived stromal cells ameliorates pulmonary emphysema.

Adipose tissue is a useful tool for management of most complex cardiothoracic problems, including the reinforcement of damaged lungs, and adipose tissue-derived stromal cells (ASCs) have been suggested to secrete hepatocyte growth factor (HGF), a multipotent regenerative factor that contributes to the repair process after lung injury. The goal of this study was to demonstrate the therapeutic impact of autologous transplantation of ASCs through HGF supplementation for the enhancement of alveolar repair in a rat model of emphysema. ASCs were isolated from inguinal subcutaneous fat pads and characterized by flow cytometry. Cultured ASC were found to secrete significantly larger amounts of HGF (15 112 +/- 1628 pg per 10(6) cells) than other angiogenic factors. Transplantation of ASCs into elastase-treated emphysema models induced a significant increase in endogenous HGF expression in lung tissues with a small amount of increase in other organs, with the high levels lasting for up to 4 weeks after transplantation. Further, alveolar and vascular regeneration were significantly enhanced via inhibition of alveolar cell apoptosis, enhancement of epithelial cell proliferation and promotion of angiogenesis in pulmonary vasculature, leading to restoration of pulmonary function affected by emphysema. These data suggest that autologous ASC cell therapy may have a therapeutic potential for pulmonary emphysema, through inducing HGF expression selectively in injured lung tissues.

Adipose Tissue↗

PubMed2005

Three-dimensional mesoporous titanosilicates prepared by modified sol-gel method: Ideal gold catalyst supports for enhanced propene epoxidation.

Mesoporous titanosilicates with 1-12 mol % Ti content and with three-dimensional wormhole-like mesoporosity are prepared by a modified sol-gel technique. Sorption analysis shows that there is little change in the surface properties with increasing Ti concentration in the samples, implying that Ti atoms either are well-dispersed on the walls of the silica matrix or are present inside the framework with no pore blocking effect. Spectroscopic analysis shows that the Ti atoms are atomically dispersed in the silica matrix even at very high Ti concentration and there is no observable Ti aggregate (anatase) present in the samples. These titanosilicate samples after Au deposition followed by trimethylsilylation (for enhanced hydrophobicity) are highly efficient catalysts for vapor-phase propene epoxidation using O2 and H2. It was possible to achieve commercially desirable performance with about 7% propene conversion, >90% propene oxide selectivity, and about 40% hydrogen efficiency.

Journal Article↗

PubMed2005

Urethral transitional cell carcinoma in a cat.

A 15-year-old, male neutered cat was referred for investigation of dysuria. A retrograde urethrography was performed which showed two space-occupying masses within the lumen of the mid-to-proximal urethra. Exploratory coeliotomy revealed two urethral masses. Segmental urethrectomy was performed to resect the mass, and the lower urinary tract was reconstructed by vesico-urethral anastomosis. Histopathology showed the mass to be a transitional cell carcinoma with incomplete surgical margins. Tumour regrowth was suspected when dysuria was found approximately 318 days after surgery. Clinical signs were palliated by radiation using weekly fractions of 6 Gy for three weeks. The cat died of unknown causes 386 days postoperatively.

Anastomosis, Surgical↗

PubMed2004

Epitope analysis of monoclonal antibody E5/G6, which binds to a linear epitope in the nucleocapsid protein of hantaviruses.

Monoclonal antibody E5/G6 recognized a linear epitope common to hantavirus nucleocapsid proteins. Using synthetic peptides, we identified epitope E5/G6 as the 9 mer YEDVNGIRK (NP 165-173), in which D167, G170, I171, and R172 are indispensable. Furthermore, all the peptides synthesized using various hantavirus sequences bound MAb E5/G6 consistently, despite the existence of several amino acid variations in this region. These results indicate that MAb E5/G6 is a useful tool for detecting hantavirus antigen in rodent or patient tissues using Western blotting or other immunohistochemical assays.

Amino Acid Sequence↗

PubMed2004

Age-dependent hantavirus-specific CD8(+) T-cell responses in mice infected with Hantaan virus.

To investigate age-dependent differences in hantavirus-specific CD8(+) T-cell responses, mice were inoculated with 0.1 50% newborn mouse lethal dose of Hantaan virus (HTNV) at 0, 3, 7, 14, or 35 days after birth. HTNV-specific CD8(+) T cells producing gamma interferon (IFN-gamma) were measured on day 30 after HTNV inoculation. Although no IFN-gamma-producing HTNV-specific CD8(+) T cells were detected in most of the mice inoculated with HTNV on day 0 after birth, most mice inoculated at 3, 7, 14, or 35 days had HTNV-specific CD8(+) T cells. The production of tumor necrosis factor alpha (TNF-alpha) by IFN-gamma-producing CD8(+) T cells and the cytotoxic activity against HTNV-infected target cells were similar in immature and adult mice. However, the number of IFN-gamma-producing HTNV-specific CD8(+) T cells was significantly less in mice inoculated with HTNV at 3 days than in older mice. In addition, a strong correlation between HTNV persistence and a lack of HTNV-specific CD8(+) T cells was observed. These results suggest that mice over 7 days old have the ability to induce functional HTNV-specific CD8(+) T-cell responses that are indistinguishable from the responses of adult mice, and that HTNV-specific CD8(+) T cells are important for clearance of HTNV.

Aging↗

PubMed2004

Identification of M1 and M2 muscarinic acetylcholine receptors in the cat carotid body chemosensory system.

The carotid body is a major arterial chemoreceptor that senses low O2 tension, high CO2 tension and low pH in the arterial blood. It is generally believed that neurotransmitters, including acetylcholine (ACh), participate in the genesis of afferent neural output from the carotid body and modulate the function of chemoreceptor cells (glomus cells). Previous pharmacological studies suggest that M1 and M2 muscarinic ACh receptors (mAChRs) are involved in these processes. This study was designed to demonstrate the presence and localization of M1 and M2 mAChRs in the carotid body and in the petrosal ganglion of the cat. Since DNA sequences of the cat M1 and M2 mAChRs were not known, we first determined partial DNA sequences. These sequences and deduced amino acid sequences highly resembled those of human and the rat. Subsequent reverse transcription-polymerase chain reaction (RT-PCR)analysis has demonstrated that mRNAs for M1 and M2 mAChRs are present in the carotid body and the petrosal ganglion of the cat. Immunohistochemistry has indicated that the localization of these receptors appears different. Immunoreactivity for M1 mAChR was strong in nerves in the carotid body. Nerve endings positively stained for M1 mAChR appear to innervate glomus cells. Weak staining for M1 mAChRs was seen in glomus cells. On the other hand, M2 receptor protein seems to be present in glomus cells but not on nerve endings. One third of the neurons in the petrosal ganglion showed immunoreactivity for M1 mAChR. Many neurons and nerve fibers in the petrosal ganglion expressed M2 mAChR immunoreactivity. The results were consistent with previous pharmacological studies. Thus, activation of M1 mAChRs on afferent nerve endings may be linked to the increase in neural output during hypoxia. Further, M1 and M2 mAChRs on glomus cells modulate the release of neurotransmitters.

Acetylcholine↗

PubMed2004

Sedation for paediatric stereotactic radiosurgery: the dexmedetomidine experience.

Dexmedetomidine is a potent alpha2 adrenergic agonist, with sedative and analgesic properties which may make it a suitable sedative agent for procedures on paediatric patients. A six-year-old boy required sedation for stereotactic radiosurgical ablation of an arteriovenous malformation on two occasions. Sedation with dexmedetomidine was planned, with increased dosage used on the second occasion. On both occasions dexmedetomidine was inadequate as a sole agent and required supplementation with other agents.

Anesthesia Recovery Period↗

PubMed2004

[Posterior mediastinal paraganglioma with a 60-year history; report of a case].

We report a case of a 68-year-old man with a posterior mediastinal tumor. He remembered having difficulty in food passage through his esophagus in childhood. The preoperative thoracic computed tomography (CT) revealed a 5 x 3 cm mass with strong enhancement in the posterior mediastinum. A right thoracotomy was performed to resect this indeterminate mass. Complete resection was achieved. The pathologic diagnosis was paraganglioma. Postoperatively, he experienced more comfortable food passage through his esophagus than ever before. There has been no sign of recurrence 3 years after the operation. The tumor was clinically diagnosed as benign paraganglioma because of its long silent course.

Aged↗

PubMed2003

Detection of antibody for the serodiagnosis of hantavirus infection in different rodent species.

Peroxidase-labeled staphylococcal protein A, streptococcal protein G, and antibodies directed against Mus musculus (mouse), Rattus norvegicus (rat), Mesocretus auratus (hamster), and Peromyscus leucopus were examined for their reactivity with immunoglobulin G (IgG) from various rodent species. The purpose of this study was to identify the optimal secondary antibodies or reagents for specific serodiagnosis of hantavirus infection in various rodent species. Using ELISA, a total of 65 sera from 29 rodent species of the family Muridae and one serum sample from family Octodontidae were compared for IgG reactivity with the six different reagents. The results demonstrate that the reactivities of the secondary antibodies and reagents to the sera varied, even among sera from rodents of the same genus. Hantavirus-specific antibody ELISA revealed that hantavirus-infected rodent sera obtained from M. musculus, R. norvegicus, Apodemus agrarius, A. peninsulae, and Bandicota indica bound to the six different conjugates in a similar pattern as that detected in IgG ELISA. These results indicate that the applicability of secondary antibodies and protein A and G should be carefully evaluated before use for serodiagnosis in different rodent species.

Animals↗

PubMed2003

Biological properties of allogenic articular chondrocytes on the surface of bovine cartilage explants in vitro.

Bovine cartilage explants were co-cultured with or without allogenic chondrocytes for 4 weeks. The attachment of the applied chondrocytes to cartilage after labelling with fluorescence was assessed using a confocal laser microscope. Morphological changes and the production of extracellular matrix (ECM) of co-cultured chondrocytes on intact and damaged surfaces of cartilage were evaluated by histological and immunohistochemical methods. Co-cultured chondrocytes attached to and proliferated on the intact and damaged areas of cartilage, and a new layer was created there. The defects were also filled with ECM produced by the co-cultured chondrocytes. Glycosaminoglycans and collagen type II were detected in the newly formed ECM, and large numbers of rounded chondrocytes were observed at primitive lacunae in this matrix at 4 weeks of culture. The results suggest that chondrocytes have the ability to attach to, to proliferate on and to establish a new matrix on the intact and damaged surfaces of cartilage explants.

Animals↗

PubMed2002

Cell cycle dependence of boron uptake from two boron compounds used for clinical neutron capture therapy.

In neutron capture therapy, it is important that the boron is selectively uptaken by tumor cells. In the present study, we used flow cytometry to sort the cells in the G0/G1 phase and those in the G2/M phase, and the boron concentration in each fraction was measured with inductively coupled plasma atomic emission spectroscopy. The results revealed that sodium borocaptate and boronophenylalanine (BPA), were associated with higher rates of boron uptake in the G2/M than in the G0/G1 phase. However, the difference was more prominent in the case of BPA. The G2/M:G0/G1 ratio decreased as a function of exposure time in BPA containing culture medium, thereby indicating the cell cycle dependency of BPA uptake. Such heterogeneity of boron uptake by tumor cells should be considered for microdosimetry.

Animals↗

PubMed2002

Serum keratan sulphate as a cartilage metabolic marker in horses: the effect of exercise.

Keratan sulphate (KS) concentration in sera from resting horses and horses training daily on a racetrack was measured by an inhibition enzyme-linked immunosorbent assay (ELISA) using anti-equine KS antibody 1/14/16H9. For the in-training horses, serum KS concentrations in 2-year-old-horses was significantly higher than 3- or 4-year-old-horses. A higher concentration of serum KS was found in the in-training group than in the long-term resting group in 2-year-old-horses. Serum KS concentration increased remarkably immediately after training in healthy horses, and at 1, 5, 9 and 24 h after training remained at similar levels to the pre-training concentration. The results suggest that serum KS concentration could represent the situation of joint loading, induced by daily racetrack training, affecting the metabolic activities in joint cartilage.

Age Factors↗

PubMed2002

Perianal rhabdomyosarcoma in a dog.

A perianal rhabdomyosarcoma was diagnosed in an 11-year-old neutered male Labrador retriever. Following two incomplete surgical excisions of the tumour, the dog was treated by means of surgery combined with local radiotherapy and systemic chemotherapy using one cycle of vincristine sulphate, doxorubicin and cyclophosphamide (VAC protocol). The dog died 252 days after the first combined therapy. Radiography at this time demonstrated enlargement of the iliac lymph nodes, suggesting metastasis of the tumour. To the authors' knowledge, this is the first report of treatment of canine perianal rhabdomyosarcoma.

Animals↗

PubMed2002

[Cavernous hemangioma in the anterior mediastinum; report of a case].

A rare case of mediastinal hemangioma was reported in this article. A 63 years old male was pointed out an abnormal shadow in the chest CT scan though he had no symptoms. It showed a well-defined round mass with low density in the anterior mediastinum. MRI (T2 weight) showed the lesion as a high intensity tumor. We diagnosed it thymoma and planned the surgical treatment. The tumor was resected completely through median partial sternotomy. The tumor was 2 cm in diameter. Histological examination revealed it cavernous hemangioma, and neither coagulations nor phleboliths were identified in vessels of the tumor.

Hemangioma, Cavernous↗