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Biomedical subjects

Yasuhiro Tanaka

Publications and source records attributed to Yasuhiro Tanaka.

At least 37 records · Page 2Linked to original sources
PubMed2005

Late development of mitral regurgitation after left ventricular reconstruction surgery.

PURPOSE: Late presence of mitral regurgitation (MR) after the Dor procedure (left ventricular (LV) reconstruction associated with coronary artery bypass grafting) for postinfarction patients carries a poor prognosis. The aim of this study was to review our experience with the Dor procedure and to analyze the correlation of surgical results with late MR. METHODS: The study group comprised 19 patients with previous anterior transmural myocardial infarction (MI). Ten patients were classified as New York Heart Association (NYHA) functional class III or IV at surgery. MR was moderate in 2 patients and mild in 15 patients. RESULTS: Myocardial revascularization was performed in all patients, with a mean of 3.7+/-1.2 grafts. Mitral valve was repaired in 6 patients. Four patients with mild MR underwent posterior annuloplasty, and 2 with moderate MR underwent rigid annular remodeling. Early postoperative NYHA functional class improved from 2.7+/-0.9 to 1.3+/-0.5; however, MR deteriorated to moderate in 5 patients with worsening NYHA functional class 3 months after surgery. Although the valve was not repaired during surgery in 4 patients with preoperative mild MR, 1 patient with moderate MR underwent annuloplasty with a rigid ring. All patients with late MR underwent more than 30-mL/m2 reduction of end-diastolic volume index at surgery. Cumulative 4-year survival including hospital deaths was 89.5%. CONCLUSION: To prevent the risk of late MR, a more than 30-mL/m2 reduction of end-diastolic volume index should be avoided and mitral valve repair should be performed even if preoperative functional MR is only mild.

Aged↗
PubMed2005

[Renal insufficiency caused by leukemic cell infiltration in Sézary syndrome].

A 77-year-old woman was admitted to our hospital because of pneumonia and heart failure in July 2002. She had been diagnosed as having with Sézary syndrome in 1993, and had been treated with a combination of prednisolone, methotrexate, and cyclosporin A with subsequent stable disease but persistent generalized erythroderma. On admission, the white blood count was 23.9 X 10(9)/L with 28% Sézary cells, and serum creatinine levels were within normal limits. One month after admission, the pneumonia and heart failure improved remarkably with antibiotics and diuretics. However, at the same time, her renal function deteriorated with increasingly high serum creatinine levels. She died of anuria in September, 2002. An autopsy showed marked perivascular and peritubular infiltration of abnormal lymphocytes with degenerative nephrotubuli in the kidneys. This patient may be the first reported case of Sézary syndrome with renal failure caused by leukemic infiltration.

Aged↗
PubMed2004

Prevalence and time of appearance of Brugada electrocardiographic pattern in young male adolescents from a three-year follow-up study.

The prevalence of Brugada's electrocardiographic (ECG) pattern in 7,022 male adolescents in the seventh grade was determined, and the same subjects were reexamined 3 years later, while in tenth grade. Two subjects (0.03%) and 7 subjects (0.10%) showed Brugada's ECG pattern by the conventional criterion (J point or ST-segment >/=0.1 mV in leads V(1) to V(3)), and no subjects (0%) and 2 subjects (0.03%) fulfilled the recent criterion (J point or ST-segment >/=0.2 mV) in the seventh and tenth grades, respectively, indicating that Brugada's ECG pattern begins to appear during junior high school and increases until late adulthood.

Adolescent↗
PubMed2004

Development of antigen-specific CD8+ CTL in MHC class I-deficient mice through CD4 to CD8 conversion.

CD8+ CTL are the predominant tumoricidal effector cells. We find, however, that MHC class I-deficient mice depleted of CD8+ T cells are able to mount an effective antitumor immunity after immunization with fused dendritic/tumor cells. Such immunity appears to be mediated by the generation of phenotypic and functional CD8+ CTL through CD4+ to CD8+ conversion, which we have demonstrated at the single cell level. CD4+ to CD8+ conversion depends on effective in vivo activation and is promoted by CD4+ T cell proliferation. The effectiveness of this process is shown by the generation of antitumor immunity through adoptive transfer of primed CD4 T cells to provide protection against tumor cell challenge and to eliminate established pulmonary metastases.

Adoptive Transfer↗
PubMed2004

Induction of anti-leukemic cytotoxic T lymphocytes by fusion of patient-derived dendritic cells with autologous myeloblasts.

Presentation of AML antigens by dendritic cells (DC) could potentially induce a T cell-mediated anti-leukemic immune response. In the present study, we generated DC from adherent (AD-DC) and non-adherent (NAD-DC) myeloblasts obtained from bone marrows of AML patients. Both cell populations displayed morphological, phenotypic and functional properties of DC. The functions of NAD-DC were compared to AD-DC that had been fused with autologous AML blasts (FC/AML). The FC/AML induced greater T cell proliferation and CTL activity against autologous AML blasts (9/10 cases) as compared to NAD-DC. FC/AML may thus represent a promising strategy for DC-based immunotherapy of patients with AML.

Adult↗
PubMed2004

Tensile properties and hardness of cast Fe-Pt magnetic alloys.

STATEMENT OF PROBLEM: There is little information about the mechanical properties of castable magnetic attachments made of iron-platinum (Fe-Pt) alloys after heat treatment. MATERIAL AND METHODS: Dumbbell-shaped tensile specimens were cast with 5 alloys: 2 types of Fe-Pt alloys for magnets and keepers, pure Ti, Ti-6Al-7Nb, and Co-Cr alloy. The tensile specimens of the Fe-Pt magnets and keepers underwent different heat treatments to obtain the appropriate properties for a magnet and a keeper. Vickers hardness was measured prior to testing. Tensile testing was conducted in a universal testing machine at a crosshead speed of 2 mm/min until failure. Ultimate tensile strength, yield strength, elongation, and modulus of elasticity were recorded. The data were analyzed using 1-way analysis of variance and the Tukey test (alpha=.05), fractured surfaces were examined using a scanning electron microscope (SEM). RESULTS: The highest tensile and yield strengths were found for Ti-6Al-7Nb, followed by Co-Cr, CP Ti, and the Fe-Pt keeper. There was no significant difference in ultimate tensile strength between the CP Ti and the Fe-Pt keeper. The lowest elongation was found for the Fe-Pt magnet (2.8%), whereas the Fe-Pt keeper had the highest elongation (14.0%). The Fe-Pt magnet and keeper had similar modulus of elasticity values. The hardness of the cast Fe-Pt magnets was the highest among the metals tested. SEM micrographs of the Fe-Pt keepers showed a microstructure with ductile dimple fractures, whereas the Fe-Pt magnets were characterized by brittle fractures at the grain boundaries. CONCLUSIONS: The mechanical properties of the cast Fe-Pt keepers were similar to those of the cast pure Ti. The Fe-Pt magnets were extremely hard and brittle.

Analysis of Variance↗
PubMed2004

Catellibacterium nectariphilum gen. nov., sp. nov., which requires a diffusible compound from a strain related to the genus Sphingomonas for vigorous growth.

A bacterial strain, designated AST4(T), was isolated from activated sludge. The bacterium did not show significant growth on nutrient broth, but growth was clearly stimulated by addition of supernatant from other bacterial cultures. Culture filtrate of a strain related to the genus Sphingomonas in particular increased the cell yield and growth rate of strain AST4(T). Phylogenetic analysis based on the 16S rRNA gene sequences showed that strain AST4(T) is located within the 'Rhodobacter group' in the alpha-3 subclass of Proteobacteria, but is clearly distant from related genera in this group such as Paracoccus, Rhodobacter and Rhodovulum. Strain AST4(T) is a Gram-negative, non-motile, rod-shaped (0.6-0.8x1.3-2.0 micro m) and aerobic bacterium. It was not able to reduce nitrate to nitrite or N(2). No phototrophic growth was observed. Optimal growth occurred at 30 degrees C and pH 6.5-7.5. The dominant cellular fatty acid in the isolate was C(18 : 1)cis11. Ubiquinone-10 was the major respiratory quinone. The G+C content was 64.5 mol% (by HPLC). Based on the phylogenetic and phenotypic traits, the name Catellibacterium nectariphilum gen. nov., sp. nov. is proposed for this isolate; the type strain is AST4(T) (=NBRC 100046(T)=JCM 11959(T)=DSM 15620(T)).

Base Composition↗
PubMed2004

Risperidone is effective for wandering and disturbed sleep/wake patterns in Alzheimer's disease.

Behavioral and psychological symptoms of dementia (BPSD), especially aggressiveness, wandering, and sleep disturbance, are a major burden for caregivers. Daily sleep/wake patterns and wandering of institutionalized patients with Alzheimer's disease (AD) were visually monitored, and 34 patients who manifested wandering were selected and randomly classified into 2 groups: the risperidone group and the nonrisperidone group. After an administration of low-dose risperidone for the risperidone group, the BPSD were reassessed. The binding potentials of dopamine D2 receptor for preadministration and postadministration of risperidone were assessed using positron emission tomography (PET) for 1 case. After the use of risperidone, aggressiveness and wandering were reduced and the nighttime sleeping hours were increased. The PET revealed that the binding potential of dopamine receptor was increased after administration of the drug, associated with improved sleep/wake patterns and behavioral abnormality. Possible serotonergic modulation of dopaminergic function might explain the neurobiological basis of the effect of risperidone.

Aged↗
PubMed2004

[Severe hyponatremia with consciousness disturbance caused by hydroxyurea in a patient with chronic myeloid leukemia].

A 79-year-old man was admitted because of consciousness disturbance on August 9, 2002. He had been diagnosed as having chronic myeloid leukemia in 1999, and since then, he had continued to take hydroxyurea (1500 mg/day) orally. On admission, his serum sodium concentration was as low as 119 mEq/L, while urinary sodium excretion was high. Based on the blood picture and lack of hepatosplenomegaly, we considered that the leukemia was still in the chronic phase. Because of normal blood level of the antidiuretic hormone (ADH) concentration and sufficient urine volume, the syndrome of inappropriate ADH secretion (SIADH) was unlikely, and sodium-losing nephropathy was suspected. After discontinuation of hydroxyurea, the urinary sodium excretion decreased and the patient's consciousness became clear concomitantly with improvement in the serum Na level. This patient appears to be the first case of hyponatremia caused by hydroxyurea.

Aged↗
PubMed2004

[Pleural involvement in the course of chronic myelomonocytic leukemia and the development of multiple colonic perforation due to leukemic infiltration in the acute leukemia phase].

A 68-year-old man with chronic myelomonocytic leukemia (CMML) was initially treated with hydroxyurea with subsequent stable disease. In the time course, he developed bilateral pleuritis accompanied by leukocytosis and spiking fever. Cytologic analysis of the pleural effusion revealed abundant mature granulocytes and monocytes. He was treated with intravenous or oral etoposide with consequent resolution of the pleuritis, indicating the pleural involvement of CMML. Three months later, he developed hepatomegaly and became febrile. One month thereafter, the CMML transformed to acute myeloid leukemia, and the patient developed massive bloody stools associated with epigastric pain and leukocytosis. A gastrofiberscopic examination showed multiple bleeding gastric ulcers. The bleeding ulcers were treated with the clipping procedure; however, the bloody stools continued. Although intravenous etoposide was effective for the leukocytosis and hepatomegaly, the treatment did not improve the bloody stools. The patient finally died of panperitonitis. The autopsy showed multiple ulcers of the transverse colon, some of which were perforated. Microscopically, the ulcerated areas were densely infiltrated with leukemic cells predominantly consisting of immature monocytes and granulocytes. This patient may be the first reported case of CMML complicated by colonic perforation due to leukemic infiltration.

Aged↗
PubMed2003

Remarkable effect of pore size on the catalytic activity of mesoporous silica for the acetalization of cyclohexanone with methanol.

The catalytic activity of mesoporous silica (MCM-41) for the acetalization of cyclohexanone shows a volcano-shaped dependence on the pore diameter. The diameter of the cyclohexanone molecule is ca. 0.75 nm, while its acetalization with methanol was well accelerated on MCM-41 with a pore diameter of approximately 1.9 nm, and smaller or larger pores were not suitable for the catalysis. The catalytic activity was independent of the Al concentration.

Journal Article↗
PubMed2003

Impaired adrenocorticotropic hormone response to bacterial endotoxin in mice deficient in prostaglandin E receptor EP1 and EP3 subtypes.

Sickness evokes various neural responses, one of which is activation of the hypothalamo-pituitary-adrenal (HPA) axis. This response can be induced experimentally by injection of bacterial lipopolysaccharide (LPS) or inflammatory cytokines such as IL-1. Although prostaglandins (PGs) long have been implicated in LPS-induced HPA axis activation, the mechanism downstream of PGs remained unsettled. By using mice lacking each of the four PGE receptors (EP1-EP4) and an EP1-selective antagonist, ONO-8713, we showed that both EP1 and EP3 are required for adrenocorticotropic hormone release in response to LPS. Analysis of c-Fos expression as a marker for neuronal activity indicated that both EP1 and EP3 contribute to activation of neurons in the paraventricular nucleus of the hypothalamus (PVN). This analysis also revealed that EP1, but not EP3, is involved in LPS-induced activation of the central nucleus of the amygdala. EP1 immunostaining in the PVN revealed its localization at synapses on corticotropin-releasing hormone-containing neurons. These findings suggest that EP1- and EP3-mediated neuronal pathways converge at corticotropin-releasing hormone-containing neurons in the PVN to induce HPA axis activation upon sickness.

Adrenocorticotropic Hormone↗
PubMed2003

Free fatty acids regulate insulin secretion from pancreatic beta cells through GPR40.

Diabetes, a disease in which carbohydrate and lipid metabolism are regulated improperly by insulin, is a serious worldwide health issue. Insulin is secreted from pancreatic beta cells in response to elevated plasma glucose, with various factors modifying its secretion. Free fatty acids (FFAs) provide an important energy source as nutrients, and they also act as signalling molecules in various cellular processes, including insulin secretion. Although FFAs are thought to promote insulin secretion in an acute phase, this mechanism is not clearly understood. Here we show that a G-protein-coupled receptor, GPR40, which is abundantly expressed in the pancreas, functions as a receptor for long-chain FFAs. Furthermore, we show that long-chain FFAs amplify glucose-stimulated insulin secretion from pancreatic beta cells by activating GPR40. Our results indicate that GPR40 agonists and/or antagonists show potential for the development of new anti-diabetic drugs.

Animals↗
PubMed2003

Prevention of spontaneous breast carcinoma by prophylactic vaccination with dendritic/tumor fusion cells.

Genetically modified mice with spontaneous development of mammary carcinoma provide a powerful tool to study the efficacy of tumor vaccines, since they mimic breast cancer development in humans. We used a transgenic murine model expressing polyomavirus middle T oncogene and mucin 1 tumor-associated Ag to determine the preventive effect of a dendritic/tumor fusion cell vaccine. The MMT (a transgenic murine model) mice developed mammary carcinoma between the ages of 65-108 days with 100% penetrance. No spontaneous CTL were detected. However, prophylactic vaccination of MMT mice with dendritic/tumor fusion cells induced polyclonal CTL activity against spontaneous mammary carcinoma cells and rendered 57-61% of the mice free of the disease at the end of experiment (180 days). Furthermore, the level of CTL activity was maintained with multiple vaccinations. The antitumor immunity induced by vaccination with dendritic/tumor fusion cells reacted differently to injected tumor cells and autochthonous tumor. Whereas the injected tumor cells were rejected, the autochthonous tumor evaded the attack and was allowed to grow. Collectively these results indicate that prophylactic vaccination with dendritic/tumor fusion cells confers sufficient antitumor immunity to counter the tumorigenesis of potent oncogenic products. The findings in the present study are highly relevant to cancers in humans.

Animals↗
PubMed2003

Decreased striatal D2 receptor density associated with severe behavioral abnormality in Alzheimer's disease.

OBJECTIVES: Since patients manifesting behavioral and psychological symptoms of dementia (BPSD) are a burden for their families and caregivers, the underlying neurobiological mechanism of this condition should be clarified. Using positron emission tomography (PET), we previously reported that wandering behavior in dementia was associated with a disturbed dopaminergic neuron system. We herein investigated the relationship between the severity of BPSD and the striatal D2 receptor density in Alzheimer's disease (AD). METHODS: Ten patients with probable AD as per the National Institute of Neurological and Communicative Disorders and Stroke (NINCDS) and the AD and Related Disorders Association (ADRDA) criteria and five normal subjects were examined with PET. The tracer used was [11C]raclopride (D2 antagonist). The uptake of [11C] raclopride was calculated as the estimation of binding potential (BP) of the striatum to the cerebellum. The AD patients were institutionalized in multiple nursing homes, and their BPSD were evaluated by the Behavioral Pathology in AD Frequency Weighted Severity Scale (BEHAVE-AD-FW) scale (Reisberg). RESULTS: There was a significant inverse Spearman's correlation between BEHAVE-AD-FW score and the BP, especially between the score of the behavioral domain and the BP values. The BP was found to be lower in severer BPSD patients. CONCLUSIONS: Patients with AD who manifest severe BPSD may have some dysfunction of striatal dopamine metabolism compared with those without BPSD.

Aged↗
PubMed2003

Naphtho[1,2- b]thiophene degradation by Pseudomonas sp. HKT554: involvement of naphthalene dioxygenase.

Pseudomonas sp. strain HKT554 degrades naphtho[1,2- b]thiophene and two other isomers, naphtho[2,1- b]thiophene and naphtho[2,3- b]thiophene, by cometabolism, in the absence of any specific inducer, at similar degradation rates. A mutant of strain HKT554, deficient in dibenzothiophene degradation, was generated by using a recently developed transposition system. Sequence analysis of the mutant revealed that the knocked out gene was almost identical to naphthalene dioxygenase (EC 1.14.12.12). The mutant, HKT554M, degraded neither the naphthothiophene isomers nor dibenzothiophene, suggesting that the naphthalene dioxygenase is responsible for the initial catabolic reactions onto naphthothiophenes and dibenzothiophene.

Biodegradation, Environmental↗
PubMed2003

Long-term survival and prognostic factors in the surgical treatment for intrahepatic cholangiocarcinoma.

BACKGROUND/PURPOSE: We retrospectively investigated the clinicopathologic features and outcome of 51 patients who underwent hepatectomy for intrahepatic cholangiocellular carcinoma (ICC) between 1991 and 2000, and we also analyzed the potential prognostic factors for long-term survival. METHODS: There were 27 men and 24 women, with a mean age of 63.7 years. The surgical procedures were extended right or left hepatectomy (15 cases), right or left hepatectomy (19 cases), bisegmentectomy (3 cases), segmentectomy (7 cases), and subsegmentectomy (7 cases). The macroscopic findings of the excised tumor showed the mass-forming (MF) type (31 cases), the periductal-infiltrating (PI) type (13 cases), and the intraductal growth (IG) type (7 cases). RESULTS: The patients with the MF type had a significantly higher incidence of lymph node metastasis (44.8%), as compared to those with the PI or IG type (15.0%). Two patients who died of hepatic failure during their hospital stay were excluded from this survival study. The cumulative 1-, 3-, and 5-year survival rates in 49 patients who underwent liver resection were 68.2%, 44.1%, and 32.4%, respectively. The patients with the IG type had the best outcome, followed by those with the PI type and MF type. The survival rates with or without lymph node metastasis were 9.0% and 60.6% at 3 years, and 9.0% and 42.9% at 5 years, respectively ( P << 0.05). The 1-, 2-, and 3-year survival rates in the MF-type patients with lymph node metastasis were 25.4%, 16.9%, and 0%, respectively. Eight patients (15.7%) survived for more than 5 years after operation. The gross appearance of these tumors was the PI type in 5 patients, the IG type in 2, and the IG + MF type in 1. Except for one case with the PI-type tumor, lymph node metastasis was not observed. All of the 5-year survivors underwent curative resection and none of them had any positive surgical margin. CONCLUSION: Analysis of the clinicopathologic factors influencing the survival after surgical treatment showed that the macroscopic type, surgical curability, lymph node metastasis, tumor size, and cancer-free margin were the most predictive.

Aged↗