Search PubMed⌕ Search

Biomedical subjects

Masayuki Kobayashi

Publications and source records attributed to Masayuki Kobayashi.

At least 37 records · Page 2Linked to original sources

Percutaneous transcatheter coil embolization of a ventricular septal defect in a dog.

A 4-month-old male French Bulldog weighing 5.0 kg (11 lb) was referred for a heart murmur. A grade 3/6 systolic murmur was detected at the left heart base and a grade 4/6 systolic murmur was detected at the right heart base. By use of color-flow Doppler ultrasonography and cardiac catheterization, a diagnosis of supracristal ventricular septal defect (VSD) with accompanying aortic regurgitation was made. Percutaneous transcatheter coil embolization was used to close the VSD. Because residual shunt was detected via echocardiography after coil implantation, the residual shunt was followed periodically via echocardiography to detect spontaneous closure of the VSD. Volume overload in the left ventricle was detected in the dog 131 days after admission. Additional coils were placed 137 days after admission. Hemolysis resulting in hemoglobinuria was detected, but this complication was mild. In the dog of this report, results of coil occlusion for correction of VSD were promising. Thus, coil occlusion should be considered as an alternative treatment for VSD in dogs.

Animals↗

YM-53403, a unique anti-respiratory syncytial virus agent with a novel mechanism of action.

We performed a large-scale random screening of an in-house chemical library based on the inhibition of respiratory syncytial virus (RSV)-induced cytopathic effect on HeLa (human cervical carcinoma) cells, and found a novel and specific anti-RSV agent, 6-{4-[(biphenyl-2-ylcarbonyl) amino]benzoyl}-N-cyclopropyl-5,6-dihydro-4H-thieno[3,2-d][1]benzazepine-2-carboxamide (YM-53403). YM-53403 potently inhibited the replication of RSV strains belonging to both A and B subgroups, but not influenza A virus, measles virus, or herpes simplex virus type 1. A plaque reduction assay was used to determine the 50% effective concentration (EC(50)) value for YM-53403. The value, 0.20 microM, was about 100-fold more potent than ribavirin. The result of a time-dependent drug addition test showed that YM-53403 inhibited the life cycle of RSV at around 8h post-infection, suggesting an inhibitory effect on early transcription and/or replication of the RSV genome. Consistent with this result, two YM-53403-resistant viruses have a single point mutation (Y1631H) in the L protein which is a RNA polymerase for both the transcription and replication of the RSV genome. YM-53403 is an attractive compound for the treatment of RSV infection because of its highly potent anti-RSV activity and the new mode of action, which differs from that of currently reported antiviral agents.

Animals↗

Phosphorylation of CARMA1 plays a critical role in T Cell receptor-mediated NF-kappaB activation.

CARMA1 mediates T cell receptor (TCR)-induced NF-kappaB activation. However, how TCR links to CARMA1 in the signaling pathway is not clear. Here, we show that CARMA1 is inducibly phosphorylated after TCR-CD28 costimulation. This phosphorylation is likely induced by PKCtheta, since PKCtheta induces phosphorylation of CARMA1 in vitro and in vivo. Our results indicate that the PKCtheta-induced phosphorylation of CARMA1 likely occurs on Ser552 on the Linker region of CARMA1. Importantly, expression of CARMA1 mutant, in which Ser552 is mutated, fails to mediate TCR-induced NF-kappaB activation in CARMA1-deficient T cells. The functional defect of this CARMA1 mutant is likely due to the fact that this mutant cannot be phosphorylated at the critical residue, thereby failing to recruit the downstream signaling components into the immunological synapse. Together, our studies provide the first genetic evidence that the phosphorylation of CARMA1 plays a critical role in the TCR signaling pathway.

Amino Acid Sequence↗

Platelet size deviation width, platelet large cell ratio, and mean platelet volume have sufficient sensitivity and specificity in the diagnosis of immune thrombocytopenia.

We investigated the significance of the platelet indices, mean platelet volume (MPV), platelet size deviation width (PDW), and platelet-large cell ratio (P-LCR), in the diagnosis of thrombocytopenia by comparing these levels in 40 patients with hypo-productive thrombocytopenia (aplastic anaemia; AA) and 39 patients with hyper-destructive thrombocytopenia (immune thrombo-cytopenia; ITP). The sensitivity and specificity of platelet indices to make a diagnosis of ITP were also compared. All platelet indices were significantly higher in ITP than in AA, and platelet indices showed sufficient sensitivity and specificity. The area under the curve (AUC) of the receiver operating characteristics curve of platelet indices was large enough to enable the diagnosis of ITP. P-LCR and PDW had the largest AUCs, which indicated that these values were very reliable for immune thrombocytopenia. Our results suggest that these indices provide clinical information about the underlying conditions of thrombocytopenia. More attention should be paid to these indices in the diagnosis of thrombocytopenia.

Adult↗

Reconstitution of photosynthetic reaction centers and core antenna-reaction center complexes in liposomes and their thermal stability.

Photosynthetic reaction centers (RCs) and their core light-harvesting complexes (LH1-RCs), purified from a thermophile, Thermochromatium (T.) tepidum, and a mesophile, Allochromatium (A.) vinosum, were reconstituted into liposomes. The RC and the LH1-RC in the reconstituted liposomes were found intact from the absorption spectra at about 4 and 40 degrees C respectively. The thermal stability of the RCs of T. tepidum in the liposome was dependent on whether they were surrounded directly by lipids or by the core light-harvesting complexes. The results show that the RC of T. tepidum gains its thermostability through interactions with the LH1. These results are consistent with the result that the thermal stability of the LH1 in T. tepidum is similar in both the reconstituted LH1-RC liposome and ICM. This is clearly different from the mesophilic bacterium, A. vinosum. The thermal stability of RC was also affected by its subunit constitution: the RC containing a cytochrome subunit was more thermostable than the cytochrome-detached RC. This suggests that the cytochrome subunit might play a role in protecting the special pair pigments from denaturation. The thermal denaturation showed a second-order reaction dependence on time. The interaction of the pigments with proteins and/or lipids might be the cause of the second-order reaction profile.

Chromatiaceae↗

An experimental study of apico-aortic valved conduit (AAVC) for surgical treatment of aortic stenosis in dogs.

A new valved conduit was developed using a canine aortic valve. The bioprosthetic valve was fixed with glutaraldehyde and epoxy compound (Denacol-EX313/810). A vascular graft composed of ultra-fine polyester fiber (10 mm in diameter, 200 mm in length) was used. Four dogs underwent apico-aortic valved conduit (AAVC) implantation and aortic banding (bypass group, BG), while another 4 dogs underwent aortic banding without AAVC implantation (control group, CG). Cardiac catheterization and angiocardiography were performed for assessment of hemodynamics 2 weeks and 6 months after surgery. Left ventricular systolic pressure, left ventricular end-diastolic pressure and the left ventricular-aortic pressure gradient differed significantly (P<0.01) between the BG and CG dogs. Left ventricular angiocardiography showed patency of the valved conduit in all the BG dogs. Echocardiography was performed before and 2, 4 and 6 months after surgery, and showed that while pressure overload caused concentric myocardial hypertrophy in the CG dogs, the left ventricle dilated eccentrically in the BG dogs. Furthermore, relief of left ventricular pressure overload by AAVC was maintained.

Angiocardiography↗

Megaesophagus was complicated with Billroth I gastroduodenostomy in a cat.

A seven-year-old, female, domestic short hair cat was presented with a history of chronic anorexia. Radiographic examination revealed a large space-occupying calcified mass in the abdominal cavity. The mass was located in pylorus and did not extend into the duodenum and surrounding tissues. Billroth I gastroduodenostomy was conducted to remove the mass. Histopathological examination of the mass showed a lymphoma. Although Recovery following the operation was excellent, the patient showed intermittent vomiting unrelated to feeding. Radiographical examination revealed a megaesophagus, which was assumed to be a complication of the Billroth I procedure, since the condition was not observed before the procedure.

Abdominal Cavity↗

CD2+ tetraploid acute promyelocytic leukemia variant with double (15;17) translocations.

We report a patient with a variant form of CD2+ acute promyelocytic leukemia (APL) who had double translocations (15;17) in a single leukemic cell. The patient presented with severe neutropenia, thrombocytopenia, and disseminated intravascular coagulation. The bone marrow showed marked hyperplasia with large leukemic cells that had bizarre nuclear configuration and basophilic, hypogranular cytoplasm. Leukemic cells were positive for CD2, 13, 33, 34, and 56 and negative for HLA-DR. The karyotype of the abnormal clone was characterized as 92,XXYY, t(15;17)(q22;q21)x2. No other additional abnormal clone was found, and the patient's condition was diagnosed as tetraploid APL variant. Fluorescence in situ hybridization assay revealed 2 promyelocytic leukemia and retinoic acid receptor alpha (PML/RARA) fusion signals, and reverse transcription-polymerase chain reaction assay revealed short-form PML/RARA fusion transcript. Tetraploidy in APL is a very rare abnormality. Double translocations were an additional abnormality in this case, and this patient's karyotype might have had some influence on morphological characteristics, expression of CD2, and poor clinical outcome.

CD2 Antigens↗

Septic intramuscular embolism in a neutropenic patient with myelodysplastic syndrome accompanied by asymptomatic septic pulmonary emboli.

Septic embolisms are rare disorders which are associated with increased mortality and morbidity. We describe a rare case of septic intramuscular embolism accompanied by asymptomatic pulmonary embolism in a neutropenic patient. Methicillin-sensitive Staphylococcus aureus (S. aureus) was detected and multiple nodules were revealed in both thighs and lung. Although he was treated with sensitive antibiotics to .S. aureus, the symptoms remained unchanged during the neutropenic period. Fever subsided rapidly and his thigh pain disappeared after neutropenia resolved. A prompt diagnosis and optimal therapeutic decisions are critical for the reduction of mortality.

Embolism↗

Toxicity and outcome of intensive chemotherapy for acute lymphoblastic leukemia complicated with Turner's syndrome.

A 17-year-old woman was diagnosed as acute lymphoblastic leukemia (ALL). As she had chromosomal abnormalities of 44, XO, der(9)t(3;9)(q11;p13), der(10;19)(q10;p10), del(15)(q15), -16, -19, +22 with the presence of ovarian dysplasia and abnormal physical features, a diagnosis of Turner's syndrome was made. She received an induction chemotherapy, which consisted of daunorubicin, cyclophosphamide, vincristine, L-asparaginase and prednisolone. Although, severe liver dysfunction was observed, the patient achieved a complete remission (CR) on day 31 following chemotherapy and has maintained CR for more than five years. The recording of such cases may well be of value to clarify toxicity and outcome after chemotherapy for patients with ALL complicated with Turner's syndrome.

Adolescent↗

Long-term follow-up high-dose chemotherapy (drug-only program) followed by autologous stem cell transplantation for aggressive non-Hodgkin's lymphomas.

PURPOSE: To investigate the feasibility of high-dose chemotherapy (HDCT) followed by autologous stem cell transplantation (ASCT) for aggressive non-Hodgkin's lymphoma (NHL), we conducted HDCT with ASCT using a drug-only protocol without total body irradiation. Previously untreated and treated adult patients with aggressive lymphoma were enrolled onto this study. For the HDCT protocol, we developed the AECC regimen, a drug-only regimen consisting of etoposide, carboplatin, cyclophosphamide, and nimustine (ie, ACNU). Mobilized peripheral blood stem cells were used mainly as a source for ASCT and were used based on collection rates of CD34 cells. PATIENTS AND METHODS: Fifty-six patients were enrolled and assessed for this study. The median length of follow-up was 6.5 years, with a range of 0.2-12.5 years. Retrospective immunophenotypic examination indicated that the majority of the patients were diagnosed with B-cell lymphoma. RESULTS: Before HDCT, 37 patients still had disease (26 partial responses [PRs] and 11 cases of no response), and 19 patients exhibited a complete response (CR) before HDCT with ASCT. Among 56 patients, 37 (66%) exhibited a CR, including patients continuing their first CR and those experiencing a second or further CR, and 11 patients (19.6%) exhibited PR on HDCT with ASCT. Outcomes of patients without CR were significantly poorer than those of the patients with CR, and 7-year overall survival rates of patients with and without CR were 63% and 27.2%, respectively. No patients developed a second malignancy, including leukemia or myelodysplastic syndrome. CONCLUSIONS: High-dose chemotherapy followed by ASCT is one of the available consolidation therapies for aggressive NHL, and additional involved-field irradiation could play a role in the management of patients with NHL who do not exhibit a CR after treatment with HDCT containing a drug-only program.

Adult↗

Early cytomegalovirus (CMV) gastrointestinal disease that developed 19 days after bone marrow transplantation, with a high-level of CMV antigenemia, of up to 1120 cells/slide.

We report a 19-year-old male with acute myeloid leukemia who developed an early cytomegalovirus gastrointestinal disease with a high level of cytomegalovirus antigenemia after bone marrow transplantation. He underwent bone marrow transplantation from HLA-matched related donor. He developed acute graft-versus-host disease on day 15, and he immediately went on prednisolone. The graft-versus-host disease disappeared immediately, but he developed a severe epigastralgia on day 23. Although absolute neutrophil count was 0.5 x 10(9)/l, the pp65 cytomegalovirus antigenemia increased up to 1120 cells/slide. The endoscope examination was performed on day 29 and it showed erosive gastritis, and microscopical examination revealed nuclear inclusion bodies and positive cells of cytomegalovirus antigen. Ganciclovir treatment was started, and it continued until negative cytomegalovirus antigenemia was confirmed. He consequently discharged to outpatient without late phase CMV diseases or recurrence of AML. We assessed that the patient had two risk factors. First, he was the cytomegalovirus seropositive patient and received bone marrow from seronegative donor. Second, he was treated with prednisolone for acute graft-versus-host disease. The ganciclovir treatment turned out to be successful, but the cytomegalovirus disease developed too early to start the antigenemia guided preemptive treatment. The high-risk patients could develop the early cytomegalovirus disease even though under the status of myelosuppression after bone marrow transplantation.

Adult↗

Beta-blocker improves survival, left ventricular function, and myocardial remodeling in hypertensive rats with diastolic heart failure.

BACKGROUND: Chronic beta-blocker therapy improves survival and left ventricular (LV) systolic function in patients with congestive heart failure. However, its efficacy in diastolic heart failure (DHF) with preserved normal LV systolic function remains uncertain. METHODS: Dahl salt-sensitive hypertensive rats fed a high-salt diet from 7 weeks of age were randomized to groups that were either not treated (DHF; n = 20) or treated with metoprolol (MP) from 7 weeks of age (DHF+7wkMP; n = 22) or from 17 weeks of age (DHF+17wkMP; n = 8). Both LV function and remodeling were evaluated by serial echocardiography, followed by hemodynamic and pathologic studies. RESULTS: Hypertension and pressure-overload LV hypertrophy were established by 17 weeks of age in DHF rats. At about 20 weeks of age DHF rats experienced overt heart failure, which was accompanied not by a decrease in LV fractional shortening but by diastolic filling abnormalities. The LV concentric hypertrophy was strikingly attenuated in DHF+7wkMP rats but not in DHF+17wkMP rats. However, LV myocardial fibrosis and the further progression of diastolic dysfunction were prevented in both MP-treated groups. Survival at 21 weeks of age was significantly improved in DHF+7wkMP (86%) and DHF+17wkMP (75%) rats compared with DHF rats (25%). CONCLUSIONS: In this study, MP prevented not only the development of LV hypertrophy but also the progression of diastolic dysfunction, and improved survival in rats with DHF. The preventive effect of MP on myocardial fibrosis is suggested as one of the mechanisms contributing to halt the progression of diastolic dysfunction, a finding that may lead to clinical benefits in regard to DHF caused by hypertension.

Adrenergic beta-Antagonists↗

Functional imaging of gustatory perception and imagery: "top-down" processing of gustatory signals.

By recalling gustatory memories, it is possible to generate vivid gustatory perceptions in the absence of gustatory inputs. This gustatory image influences our gustatory processing. However, the mechanism of the "top-down" modulation of gustatory perception in the human is still unclear. Our findings propose a new perspective on the neural basis of gustatory processing. Although gustatory imagery and gustatory perception shared common parts of neural substrates, there was an asymmetrical topography of activation in the insula: the left insula was predominantly activated by gustatory imagery tasks. In addition, the middle and superior frontal gyri were not activated by gustatory perception but they participated in the generation of gustatory hallucinations. These regions in the frontal cortex may mediate the "top-down" control of retrieving gustatory information from the storage of long-term memories.

Adult↗

Reconstitution and replacement of bacteriochlorophyll a molecules in photosynthetic reaction centers.

Reaction centers (RCs) of the photosynthetic bacterium Rhodobacter sphaeroides R-26 were reconstituted in liposomes after release of pigments (bacteriochlorophyll a (BChla) and bacteriopheophytin a (BPhea)) by treatment with acetone. As shown by absorption and circular dichroism spectroscopies, the reconstituted RCs had the same arrangement of pigments as the native RC and exhibited photoactivity of the special pair. The recovery yield of RCs of up to 30% was achieved by addition of 7.8-fold excess of BChla in the acetone treatment. Furthermore BChla was partially replaced with Zn-BChla by addition of the pigments during the acetone treatment. About 30% and 50% of the special pair and accessory pigments can be replaced with Zn-BChla, respectively. From this rate, an oxidation-reduction potential of 520 mV (vs. the normal hydrogen electrode NHE) was derived by the simulation of the experimental data, which is 35 mV higher than that of the native RC (484 mV vs. NHE).

Acetone↗