Search PubMed⌕ Search

Biomedical subjects

H Akiba

Publications and source records attributed to H Akiba.

At least 55 records · Page 3Linked to original sources
PubMed1998

CD27, a member of the tumor necrosis factor receptor superfamily, activates NF-kappaB and stress-activated protein kinase/c-Jun N-terminal kinase via TRAF2, TRAF5, and NF-kappaB-inducing kinase.

CD27 is a member of the tumor necrosis factor (TNF) receptor superfamily and is expressed on T, B, and NK cells. The signal via CD27 plays pivotal roles in T-T and T-B cell interactions. Here we demonstrate that overexpression of CD27 activates NF-kappaB and stress-activated protein kinase (SAPK)/c-Jun N-terminal kinase (JNK). Deletion analysis of the cytoplasmic domain of CD27 revealed that the C-terminal PIQEDYR motif was indispensable for both NF-kappaB and SAPK/JNK activation and was also required for the interaction with TNF receptor-associated factor (TRAF) 2 and TRAF5, both of which have been implicated in NF-kappaB activation by members of the TNF-R superfamily. Co-transfection of a dominant negative TRAF2 or TRAF5 blocked NF-kappaB and SAPK/JNK activation induced by CD27. Recently, a TRAF2-interacting kinase has been identified, termed NF-kappaB-inducing kinase (NIK). A kinase-inactive mutant NIK blocked CD27-, TRAF2-, and TRAF5-mediated NF-kappaB and SAPK/JNK activation. These results indicate that TRAF2 and TRAF5 are involved in NF-kappaB and SAPK/JNK activation by CD27, and NIK is a common downstream kinase of TRAF2 and TRAF5 for NF-kappaB and SAPK/JNK activation.

Calcium-Calmodulin-Dependent Protein Kinases↗
PubMed1998

Radiotherapy for Kimura's disease: the optimum dosage.

PURPOSE: To evaluate retrospectively the optimum dosage of irradiation for Kimura's disease. METHODS AND MATERIALS: Twenty patients with Kimura's disease were treated with radiotherapy. The sex ratio was 19 males to 1 female. The mean ages at onset, initial treatment, and radiotherapy were 26.2, 29.5, and 32.2 years, respectively. Radiotherapy was mainly applied for residual or recurrent tumors. The eosinophil count increased by more than 10% in 18 of the 20 patients. In most instances, irradiation was given through a single field with dosages ranging from 20 to 44 Gy. RESULTS: At the completion of radiotherapy, a marked response in tumor size was noted in all cases. The minimum follow-up was 48 months. Local control was obtained in 23 of 31 lesions (74.1%). At dosages of < or =25 Gy, 26-30 Gy, and > 30 Gy, local control was obtained in 2 of 8 (25.0%), 9 of 10 (90.0%), and 12 of 13 sites (92.3%), respectively. CONCLUSIONS: Radiotherapy is an effective treatment for Kimura's disease. This strongly suggests that no surgical procedure other than a biopsy should be carried out. The radiation field should be limited to the lesion and swelling of the adjacent lymph nodes as much as possible, with a optimum dosage of 26-30 Gy regardless of tumor size.

Adolescent↗
PubMed1998

Dual role of dendritic cells in the induction and down-regulation of antigen-specific cutaneous inflammation.

We have previously reported that contact sensitivity (CS) to dinitrofluorobenzene (DNFB) in C57BL/6 mice was mediated by MHC class I-restricted CD8+ T cells and down-regulated by MHC class II-restricted CD4+ T cells. In this study, we analyzed the contribution of dendritic cells (DC) in the induction of these two T cell subsets endowed with opposite functions. Hapten-pulsed skin- and bone marrow-derived DC, obtained from either normal C57BL/6 mice or from MHC class II (I+ II-) and MHC class I (I- II+)-deficient mice, were tested for their ability to prime normal mice for CS to dinitrofluorobenzene. Expression of MHC class I molecules by transferred DC was mandatory both for the induction of CS and for the generation of hapten-specific CD8+ T cells in lymphoid organs. I+ II- DC were as potent as I+ II+ DC in priming for CS, demonstrating that activation of effector CD8+ T cells can occur independently of CD4+ T cell help. I- II+ DC could not immunize for CS, although they could sensitize for a delayed-type hypersensitivity reaction to protein Ags. Moreover, I- II+ DC injected simultaneously with cutaneous sensitization down-regulated the inflammatory response, suggesting that hapten presentation by MHC class II molecules could prime regulatory CD4+ T cells. These results indicate that DC can present haptenated peptides by both MHC class I and class II molecules and activate Ag-specific CD8+ effector and CD4+ regulatory T cell subsets, concurrently and independently.

Animals↗
PubMed1998

Vascular compression of the oculomotor nerve disclosed by thin-slice magnetic resonance imaging.

PURPOSE: To describe the thin-slice magnetic resonance imaging features of vascular compressive oculomotor nerve paresis. METHODS: We performed thin-slice (2 mm thick) magnetic resonance imaging of the brainstem in a 74-year-old woman with right partial oculomotor nerve paresis using spoiled gradient recalled acquisition in the steady state. RESULTS: Thin-slice magnetic resonance images disclosed that the right oculomotor nerve was compressed and dislocated superiorly and laterally by the tortuous basilar artery. No other abnormalities were observed. CONCLUSION: This is the first case report of vascular compressive oculomotor nerve paresis disclosed by thin-slice magnetic resonance imaging.

Aged↗
PubMed1998

Diagnosis and treatment of malignant lymphoma of the parotid gland.

BACKGROUND: To correlate the imaging and pathological features and to discuss therapeutic modalities and the prognosis of malignant lymphoma originating in the parotid gland, which is relatively rare. METHODS: The subjects were five patients with malignant lymphoma originating in the parotid gland. Three and two patients were stage I and stage II, respectively. CT examination was applied to all, whereas only one case was examined by MRI. All were treated with radiotherapy following surgery or chemotherapy. Three patients underwent combination chemotherapy, such as with MACOP-P or VEPA, following surgery. RESULTS: Although malignant lymphoma originating in the parotid gland is histologically described as low-grade non-Hodgkin's lymphoma, two and one of the cases were classified as intermediate and high grade in the present series, respectively. These three exhibited a tendency for infiltration into the adjacent tissue and tumor inhomogeneity in the imaging findings, suggesting a correlation with histologically intermediate or high-grade non-Hodgkin's lymphoma. It was successfully controlled by radiotherapy, with dosages ranging from 40 to 44 Gy. The patients were followed for 2-8 years. No relapse was found in the three patients with stage I. However, both stage II patients had relapses and were subjected to additional radiotherapy combined with chemotherapy. Since then, no tumor relapse has been noted at either this or other sites. CONCLUSIONS: Malignant lymphoma including intermediate or high grade originating in the parotid gland indicated satisfactory prognosis following radiotherapy and chemotherapy.

Aged↗
PubMed1997

Serial dynamic magnetic resonance imaging of orbital cavernous hemangioma.

PURPOSE: To assess serial dynamic magnetic resonance imaging after rapid intravenous injection of contrast material as a tool for diagnosing orbital cavernous hemangioma. METHODS: Two patients with orbital cavernous hemangioma were studied. Gadolinium-DTPA, 0.1 mmol/kg, was injected intravenously in 10 seconds. RESULTS: On early imaging after the injection, one small point of enhancement was initially noted, and then the tumor was homogeneously enhanced. The initial enhancement point represented the connecting point of feeding vessels to the lesion. CONCLUSIONS: Dynamic magnetic resonance imaging is useful for diagnosing cavernous hemangioma and for estimating the connecting point of feeding vessels.

Adult↗
PubMed1997

Inhibitory effects of caffeine on Ca2+ influx and histamine secretion independent of cAMP in rat peritoneal mast cells.

1. Caffeine did not evoke Ca2+ mobilization and histamine secretion. 2. Caffeine, as well as other methylxanthines but not forskolin or 8 bromo-cAMP, inhibited Ca2+ responses from compound 48/80. 3. Evoked histamine secretion was severely reduced by caffeine but not by cAMP analogs. 4. In beta-escin-permeabilized cells, caffeine did not affect resting and IP3-stimulated 45Ca2+ release, but it inhibited Ca(2+)-induced histamine secretion. 5. These results indicate that caffeine inhibits Ca2+ influx and Ca2+ efficacy in the secretory apparatus independent of cAMP, resulting in the inhibition of secretagogs-evoked histamine secretion from rat mast cells.

Animals↗
PubMed1997

Radiotherapy of vertebral hemangiomas.

Between 1975 and 1996, 14 patients (11 females, 3 males) with vertebral hemangioma received treatment with radiotherapy. Thirteen patients had a history of back pain or lumbago and 2 patients had neurological symptoms such as sensory impairment or paraplegia. The standard dose administered was 36 Gy in 18 fractions (five treatments per week). In the 13 patients with pain, this was completely or partially relieved. The condition of a man with hypesthesia of the legs deteriorated and a woman with paraplegia who was treated with decompressive laminectomy followed by radiotherapy recovered completely after irradiation. CT scan before irradiation showed thickened trabeculae as small punctate areas of sclerosis in all patients. At MR imaging before irradiation, T2-weighted MR images showed areas of high intensity in all patients and MR images demonstrated lesion enhancement. However, none of the patients who were treated successfully with radiation demonstrated any changes of the affected vertebra in the conventional radiographic films. CT scan or MR imaging, even 5 years after irradiation. Radiological imaging is indispensable for the diagnosis of vertebral hemangiomas but does not appear to be useful for evaluating the effects of radiotherapy.

Adult↗
PubMed1996

Transient elevation of intracellular calcium ion levels as an early event in T-2 toxin-induced apoptosis in human promyelotic cell line HL-60.

Recently we have reported that T-2 toxin, a trichothecene mycotoxin produced by Fusarium species, is a potent inducer of apoptosis in the human promyelotic cell line HL-60. To clarify the signal transduction pathway of apoptosis primed by T-2 toxin, T-2 toxin-induced apoptosis was investigated in detail using confocal laser microscopy and flow cytometry. Apoptosis in HL-60 cells induced by T-2 toxin was dose dependent when the cells were treated with concentrations of 5-100 ng/ml for more than 2 hr. The apoptosis proceeds through various cell cycle stages of HL-60 cells. Prior to apoptosis, the intracellular calcium ion (Ca+2i) level was markedly elevated within 3-5 min after exposure to T-2 toxin and returned to normal level thereafter. A well-known chelator for Ca+2i, ethylene-N,N,N', N'-tetraacetic acid 4K acetoxymethyl ester (BAPTA-AM), a Ca+2-dependent endonuclease inhibitor ZnCl2, and calpain inhibitor 1 sharply blocked T-2 toxin-induced apoptosis. These results strongly suggest that the Ca+2 signal triggered by T-2 toxin is transduced by the activation of endonuclease and protease, and ultimately evokes apoptosis.

Apoptosis↗
PubMed1996

Vascular compressive abducens nerve palsy disclosed by magnetic resonance imaging.

PURPOSE: To assess magnetic resonance imaging as a diagnostic tool of neurovascular compression in a patient with abducens nerve palsy. METHODS: We performed magnetic resonance imaging of the brainstem of a 46-year-old patient with left abducens nerve palsy using spoiled gradient recalled acquisition in the steady state (SPGR), which allows high-resolution T1-weighted imaging and detection of the arteries across the plane of slices as a high-signal-intensity area. RESULTS: Computed tomography of the brain was unremarkable except for leftward shifting of the basilar artery. As disclosed by magnetic resonance imaging with the SPGR, the right vertebral artery was shifted to the left and joined with the left vertebral artery, and the left abducens nerve was compressed by the vertebral artery. No other abnormal signals were seen in the brainstem. CONCLUSIONS: These findings suggest that the abducens nerve palsy in this patient was caused by vascular compression at the root exit zone. Magnetic resonance imaging with the SPGR is useful for the diagnosis of vascular compressive neuropathy.

Abducens Nerve↗
PubMed1996

Two chicken B cell lines resistant to ouabain for the production of chicken monoclonal antibodies.

Two chicken B cell lines, termed MuH1 and MuH4, which are resistant to ouabain, were established as fusion partners for production of chicken monoclonal antibody from the parental cell lines R27H1 and R27H4 which were deficient in thymidine kinase activity. The MuH1 synthesized, but did not secrete mu chain, whereas the MuH4 secreted non-specific IgM. Fusions of the MuH1 and MuH4 with spleen cells from chickens immunized with human IgG resulted in successful preparations of hybridomas secreting antibodies specific to human IgG. Transformed cells insensitive to HAT appeared in many culture wells after cell hybridizations with R27H4, but on hybridization with MuH1 or MuH4 the appearance of such unfavorable cells could be avoided by the inclusion of ouabain in HAT medium. Thus, in comparison with the R27H4 line, the MuH1 and MuH4 lines did not provide higher fusion efficiencies, but gave increased opportunities to obtain hybridomas producing specific antibodies. Among a total of eight hybridomas, four derived from HuM1 and four derived from MuH4, seven secreted both IgG and IgM, and the remaining one derived from MuH1 secreted only IgG. In all eight hybridoma lines IgG was specifically reactive to human IgG.

Animals↗
PubMed1994

Definitive diagnosis and location of peanuts in the airways using magnetic resonance imaging techniques.

A 14-month-old boy suspected to have aspirated peanut fragments into the airways was transferred to our hospital. His chest radiographs revealed Holzknecht's sign, which indicated left mainstem bronchial obstruction. Magnetic resonance imaging with T1-weighted images clearly showed a high-intensity signal of peanut fragments in the left mainstem bronchus. Removal was performed by bronchoscopy in a shorter time under general anesthesia. Magnetic resonance imaging with T1-weighted images (T1WI) is useful for definitive diagnosis and location of peanut fragments in the lower airway because the peanut material appears as a high-intensity signal surrounded by the low-intensity lung tissue. Various slice orientations of T1WI provide accurate information concerning anatomic location of such fragments, thus facilitating removal by bronchoscopy.

Arachis↗
PubMed1991

Identification of an unusual structure in the Drosophila melanogaster transposable element copia: evidence for copia transposition through an RNA intermediate.

The Drosophila melanogaster transposable element copia is usually 5 kb long with long terminal repeats (LTRs), and its major transcripts are a full-length 5-kb RNA and a 2-kb RNA. We have previously shown that the 2-kb RNA is generated through splicing. Here, we have cloned a genomic intronless copia using an oligodeoxyribonucleotide probe which is specific for the junction of the two exons. The unusual copia is bounded by two LTRs and lacks precisely the intron of the 2-kb copia RNA. Identification of genomic intronless copia strongly suggests that copia transposes through an RNA intermediate. Moreover, we have found that copia virus-like particles (VLPs), in which reverse transcription of copia RNA seems likely to occur, packages the spliced copia RNA much less efficiently than the full-length copia RNA. This result leads to the suggestion that much lower copy number of genomic intronless copia, as compared with that of 'normal' copia, may be responsible for the inefficient packaging of the spliced copia RNA into the VLP.

Animals↗
PubMed1990

[Production of normal young following transfer of mouse embryos obtained by in vitro fertilization using cryopreserved spermatozoa].

Spermatozoa from cauda epididymis of mature mice were suspended in preservation solution (Dulbecco's PBS containing raffinose in combination with glycerol, DMSO or skim milk as freezing protective agents). The suspension was frozen by the dry ice-alcohol method and preserved for 1-120 days in liquid nitrogen (-196 degrees C). Highest sperm viability after thawing was obtained with a combination of 10% raffinose and 5% glycerol or with a combination of 10% raffinose and 10% DMSO. These frozen thawed sperm were found to have fertilizing capacity when used for in vitro fertilization. The 2-cell embryos obtained through the above procedures developed into normal pups at a high rate when transferred into the oviducts of pseudopregnant female mice.

Animals↗
PubMed1990

[Three dimensional CT reconstruction image using a personal computer].

Three dimensional (3D) images were reconstructed from axial CT slices using the personal computer. Some devices of the program made it possible to decrease the image processing time and to produce the realistic images with cubic effect. The thresholding in the conventional 3 D imaging was not practical especially in the display of the soft tissues. The employment of the volume rendering technique and MRI data will give a clue to the solution of these problems.

Humans↗
PubMed1989

Availability of 111In-labeled platelet scintigraphy in patients with postinfarction left ventricular aneurysm.

Eighteen patients with postinfarction left ventricular aneurysms (LVAs) were examined with Indium-111-labeled autologous platelet scintigraphy to identify intracardiac thrombi and to investigate the effect of antithrombotic agents on thrombogenesity within their LVAs. Left ventriculography (LVG), and two-dimensional echocardiography were also carried out to assess the diagnostic ability of the platelet imaging. Indium-111-platelet scintigraphy for the detection of LVA mural thrombi had a sensitivity of 60% and a specificity of 100%. Four of six patients with false-negative scintigraphic studies had been under antiplatelet therapy. Eight of the nine patients who had showed active platelet deposition on initial examination had not received antiplatelet therapy. Thereafter, five of these nine were treated with tichlopidine (300 mg/day) for 29.8 +/- 5.0 days. On the second platelet study, two had resolution and the other three had interruption of intra-aneurysmal deposition, which remained positive. In only one patient of the three, the third platelet study was performed after warfarin therapy. It took two weeks after beginning the therapy to completely interrupt platelet deposition within the LVA in this patient. ECG gated radionuclide ventriculography and Thallium-201-myocardial scintigraphy were also performed to assess left ventricular wall motion of left ventricular ejection fraction (LVEF) and myocardial blood perfusion. Thallium-201-SPECT showed apical or anteroapical perfusion defects and the radionuclide ventriculography correctly identified all 18 apical and anteroseptal aneurysms which were confirmed by LVG methods. The comparison between the thrombus positive group and the thrombus negative group was carried out on both the LVEF and the period from the last myocardial infarction to the initial platelet scanning study. There were no statistical differences in the LVEF and the interval (34.5 +/- 12.5% vs 37.3 +/- 14.6%, 39.6 +/- 52.6 days vs 89.6 +/- 108.3 days) between the two groups. These results suggest that Indium-111-labeled platelet scintigraphy can be a reliable method for the identification of active left ventricular mural thrombi and a practical method of judging antiplatelet and anticoagulant therapy.

Adult↗
PubMed1989

[Fundamental study of 99mTc nanocolloids for inflammation imaging].

The biodistribution of nanometer-sized colloidal particles (nanocolloids, Solco-Basle Ltd.) was examined in six rabbits with turpentine-induced abscesses in the musculature of their hind legs. 99mTc labelled colloids with a mean particle size less than 100 nm were administered to each rabbit intravenously. The biodistribution of the tracer was studied with a gamma camera 1, 3, and 24 hours after injection. Prominent uptakes were demonstrated in the liver, spleen, bone marrow, kidneys, and urinary bladder. On the other hand, the abscess and surrounding inflammatory edema were depicted as unclearly margined faint hot spots. Subsequently, the rabbits were sacrificed and activity per gram tissues were counted with a well-type gamma counter. Although the results were almost in agreement with a gamma camera study, it was noticed the activity counts in the abscess were significantly higher than that of control muscles.

Abscess↗