Search PubMed⌕ Search

Biomedical subjects

Y Miyauchi

Publications and source records attributed to Y Miyauchi.

At least 19 recordsLinked to original sources
PubMed2006

Changes in the fluorescence spectrum of individual single-wall carbon nanotubes induced by light-assisted oxidation with hydroperoxide.

Through fluorescence-spectrum measurements, we investigated the effects of light-assisted oxidation with H2O2 (LAOx) on single-wall carbon nanotubes (SWNTs) that were individually dispersed in an aqueous solution of surfactant. The intensities of the fluorescence spectra were decreased remarkably by the LAOx when the light's wavelength was 400-500 nm and a little when 600-700 nm. The spectrum intensity did not recover even when the pH was restored to an original value of 6.5. The spectra changed little when the LAOx wavelength was 500-600 nm or the light was not irradiated. In addition, the effect of LAOx on SWNTs was related to the diameters of SWNTs. We inferred that these phenomena reflected that H2O2 was dissociated by absorbing the fluorescence light emitted from optically excited SWNTs, which, in turn, accelerated the burning out of SWNTs.

Journal Article↗
PubMed2006

Presence of prostacyclin receptor in arteriosclerotic human femoral artery.

AIM: Prostacyclin, which is mainly synthesized by vascular endothelial cells, exerts antiplatelet and smooth-muscle-relaxant effects, thereby maintaining cardiovascular homeostasis. Prostacyclin analogues have been clinically proven to improve ischemic symptoms and prevent the occurrence of vascular events in the lower extremities of patients with arteriosclerosis obliterans. We examined the presence of prostacyclin receptor (IP receptor) in an arteriosclerotic human femoral artery. METHODS: Specimens of the femoral artery were obtained at the time of limb amputation from an 83-year-old woman. Atherosclerotic lesions and associated changes such as calcification were evident. The specimens were stained with hematoxylin and eosin, and processed for immunohistochemistry. RESULTS: A monolayer of cells was observed on the luminal side of the femoral artery. Single immunohistochemistry showed the presence of the IP receptors on cells of the luminal side of the femoral artery. Triple-immunofluorescence staining revealed colocalization of IP-receptor-positive cells and cells positive for von Willebrand factor, a marker of vascular endothelial cells. CONCLUSIONS: We investigated the presence of the IP receptor in the human femoral artery immunohistochemically, and demonstrated their strong expression in endothelial cells. This finding suggests that prostacyclin or prostacyclin analogues may act on their receptors on endothelial cells in patients with arteriosclerosis obliterans.

Aged, 80 and over↗
PubMed2002

Expression of p33(ING1) in hepatocellular carcinoma: relationships to tumour differentiation and cyclin E kinase activity.

BACKGROUND: Inhibitor of growth-1 (ING1) is a new candidate for the tumour suppressor gene that encodes a 33k Da protein (p33(ING1)). While reduction of p33(ING1) is an important event in some human cancers, the expression of p33(ING1) in human hepatocellular carcinoma (HCC) remains to be examined. We evaluated p33(ING1) expression in various liver diseases including HCC. METHODS: Expression of p33(ING1) was evaluated immunohistochemically not only in the normal liver (n = 5), but also in specimens of chronic hepatitis (n = 39) and HCC (n = 86). We also analysed the relationship between p33(ING1) expression and cyclin E kinase activity detected by autoradiography in 29 HCCs. RESULTS: Expression of p33(ING1) was reduced in HCC, especially in moderately and poorly differentiated HCCs, and those at advanced stages. Furthermore, expression of p33(ING1) correlated inversely with cyclin E kinase activity. CONCLUSIONS: These data suggest that reduction of p33(ING1) may contribute to the process of malignant transformation, progression and dedifferentiation of HCC via an increase of cyclin E kinase activity.

Blotting, Western↗
PubMed2002

Combined use of percutaneous ethanol injection and radiofrequency ablation for the effective treatment of hepatocelluar carcinoma.

Radiofrequency ablation (RFA) and percutaneous ethanol injection (PEI) therapy are currently used for the treatment of hepatocellular carcinoma (HCC). The purpose of this study was to evaluate the usefulness of combination therapy of PEI and RFA (PEI-RFA). Seventy-three patients with biopsy-proven HCC and liver cirrhosis underwent RFA after a bolus injection of ethanol into HCC. The volume of coagulated necrosis in the liver caused by PEI-RFA was estimated and compared with that by RFA alone. Coagulated necrosis areas in the liver of patients treated with PEI-RFA were significantly larger than those of patients treated with RFA alone. In PEI-RFA group, the volume of coagulated necrosis was significantly correlated with the amounts of ethanol injected into HCC. No major complications were observed during and after the PEI-RFA treatment. These results indicate that PEI-RFA is more effective than RFA alone and can make dramatic improvement of therapeutic effects in RFA therapy for HCC with fewer sessions of treatments. Therefore, PEI-RFA is considered to be a practical and promising option and may open up new avenues for the treatment of HCC.

Adult↗
PubMed2001

Case report: pulmonary embolism from thrombosis in a duplicated inferior vena cava developing after an electrophysiologic procedure.

Duplicated inferior cava (IVC) is an anomaly we rarely encounter during electrophysiologic procedures. We report a case with duplicated IVC who developed thrombosis of the left IVC following an electrophysiologic procedure, which resulted in an asymptomatic pulmonary embolism. It is speculated that several catheters placed in the torturous route through the left IVC caused either endothelial damage to the vessel wall, or hemostasis in the relatively narrow portion of the vessel, resulting in thrombus formation. Since the prevalence and characteristics of thrombo-embolic complications during electrophysiologic procedures in patients with a duplicated IVC remain unknown, we believe this case should be reported.

Electrophysiologic Techniques, Cardiac↗
PubMed2001

A randomized comparison of the straight linear approach with electrogram mapping focal approach in selective slow pathway ablation.

The aim of this study was to evaluate the efficacy and safety of the anatomic linear approach in selective AVN slow pathway ablation, in comparison to the widely used electrogram mapping focal approach. It remains undetermined whether or not anatomic linear ablation has a greater potential for eliminating slow pathway conduction than does focal ablation. Fifty consecutive patients (21 men, 29 women, age 56 +/- 14 years) with common type AVNRT were randomly assigned to the linear approach (25 patients) or local electrogram mapping approach (25 patients). A linear lesion was created between the tricuspid annulus, at the midlevel of the coronary sinus (CS) ostium, and the anterior aspect of the CS infundibulum. In 22 (88%) patients in the linear group, the AVNRT was successfully eliminated by 1.5 +/- 0.8 linear RF applications without any complications. All 25 patients in the focal group satisfied the endpoint criteria after 3.8 +/- 2.4 focal RF deliveries. The success rate did not significantly differ between the two groups. Out of the 22 patients with a successful outcome in the linear group, 17 (77%) attained complete abolition of the slow pathway conduction, whereas this was observed in only eight (32%) patients in the focal group (P < 0.005). The session time was significantly shorter in the linear group. Recurrence of the tachycardia was not documented in any patient during a mean follow-up of 18 +/- 8 months except one with residual slow pathway conduction in the focal ablation group. In conclusion, the anatomic linear approach can be performed safely and possesses a greater potential for slow pathway interruption compared to the electrogram mapping focal approach.

Adult↗
PubMed2001

Primary osteogenic sarcoma of a finger proximal phalanx: a case report and literature review.

Osteogenic sarcoma of the small bones of the hand is rare with only 15 cases documented. We describe a 12-year-old boy with an osteogenic sarcoma of the proximal phalanx of the middle finger. Wide excision in the form of ray amputation with a wide surgical margin was performed after neoadjuvant chemotherapy consisting of combined high-dose methotrexate, doxorubicin, ifosfamide, and cisplatin. To restore maximum function the index ray was transferred to the base of the third metacarpal. Adjuvant chemotherapy was administered subsequently. At 28-month follow-up evaluation there was no evidence of local recurrence of disease or distant metastasis and both function and appearance were good.

Amputation, Surgical↗
PubMed2001

Intraneural median nerve pressure in carpal tunnel syndrome.

In order to determine whether endoscopic carpal tunnel release decompresses the median nerve, we measured the intraneural median nerve pressure pre- and postoperatively in 55 hands. The median nerve pressure was significantly reduced postoperatively.

Carpal Tunnel Syndrome↗
PubMed2001

Morphometric nerve fiber analysis and aging process of the human inferior alveolar nerve.

We studied morphometric nerve fiber analysis and the aging process of the inferior alveolar nerve (IAN). Human IANs were resected at the mandibular foramen. The preparation of sections involved fixation, washing, dehydration, embedding, sectioning and staining as described in our previous reports. We estimated the total number of myelinated axons in the IAN being average 26,200, the transverse area of those being average 37.1 microns 2, the average perimeter of those being 23.0 microns, the average circularity ratio of those being 0.85, respectively. According to these results, the IAN did not demonstrate notable age-relation change in any measured item. The IAN differed from not only our previous data on the human motor peripheral nerves but also those on the human sensory peripheral nerves. With regard to the aging process, the IAN indicated morphological features compared with other peripheral nerves.

Aged↗
PubMed2001

[A patient with recurrent breast cancer whose liver metastasis regressed following combined use of weekly docetaxel and MPA.5'-DFUR].

A 28-year-old woman who was 10 months pregnant was diagnosed with left breast cancer. She received preoperative chemotherapy and underwent mastectomy after parturition. Endocrine therapy and adjuvant CMF and CAF was administered, but a bone metastasis appeared 2 years later and a liver metastasis 3 years later. Weekly docetaxel and MPA plus 5'-DFUR combination therapy were successively and simultaneously administered. The liver tumor regressed, and the survival time was prolonged by 1 year and 6 months. This case suggests that the combined use of both therapies was safe for the patient in serious bad condition and had a strong antitumor effect.

Adult↗
PubMed2000

Analysis of posterior mitral annular activation during entrainment and catheter ablation of mitral isthmus ventricular tachycardia using a coronary sinus catheter.

A detailed analysis of the ventricular activation along the posterior aspect of the mitral annulus was made using a multipolar catheter positioned in the coronary sinus in a patient with mitral isthmus ventricular tachycardia (VT) associated with a remote inferior myocardial infarction and prior cryosurgical ablation for the elimination of a different preexisting VT. A change in the timing and sequence of the ventricular activation along the isthmus could be observed during induction of the VT and entrainment pacing. A radiofrequency (RF) current application directed at the posterolateral region of the isthmus successfully eliminated this tachycardia. During the RF delivery, complete conduction block was confirmed by a sudden change in the activation sequence during sinus rhythm.

Aged↗
PubMed2000

Temporal and spatial dispersion of repolarization during premature impulse propagation in human intact ventricular muscle: comparison between single vs double premature stimulation.

AIMS: This study was performed to determine whether or not the kinetics of action potential duration restitution during double premature stimuli (S3) differ from that during single premature stimuli (S2) in the human intact right ventricle. METHODS AND RESULTS: A monophasic action potential (MAP) was simultaneously recorded from the right ventricular apex (RVA) and outflow tract (RVOT) during programmed ventricular pacing in 11 patients with symptomatic bradyarrhythmias (five males, six females, mean age 58 years). In the five most recent patients, the RV pressure and its dp/dt were also obtained during the protocol. A substantial difference in the restitution of the MAP duration (MAPD) between S2 and S3 was observed at short diastolic intervals (< l00 ms), that is, the restitution curve of S2 showed an early biphasic pattern (upward hump), while such a phenomenon was not seen during the restitution of S3. All the quantitative parameters of MAPD restitution representing its kinetics were significantly greater in S3 than S2. Maximum attainable dispersion of repolarization between the two MAPs was significantly greater during S3 than S2 (76 +/- 17 vs 59 +/- 17 ms, P<0.05) and was mainly caused by the difference in the MAPD difference, thus by the difference in the restitution kinetics of S2 and S3. The dp/dt of the RV pressure was significantly greater during S3 than S2 for all diastolic intervals tested. CONCLUSION: It was concluded that similar to previously reported canine experimental studies, the APD restitution of S3 is substantially different from that of S2 in the human intact ventricle (endocardium).

Action Potentials↗
PubMed2000

Identification of the slow conduction zone in idiopathic left ventricular tachycardia.

The mechanism of verapamil sensitive idiopathic left ventricular tachycardia (ILVT) is considered to be reentry. However, the nature of the reentry circuit, including the location of the slow conduction zone, is unclear. We sought the local electrical activity that would reflect slow conduction by precise mapping around the tachycardia exit (TE) in nine patients with ILVT (mean age, 28 +/- 10 years) undergoing radiofrequency catheter ablation (RFCA). The TE was defined as the earliest discrete spiky potential (SP) recorded during the tachycardia, or as a complete configuration-matched pacemap 12-lead electrocardiogram (ECG). In all patients, the TE was located at the mid or inferior distal portion of the septum. The SP at the TE preceded the surface QRS by 20 +/- 9 ms. The pacemap score at the TE was 11.4 +/- 0.6 points. In three patients, fractionated potentials (FP) were recorded during the tachycardia. The onset of the FP preceded the surface QRS by 47 +/- 8 ms and was earlier than the SP at the TE (P < 0.01). The sites where an FP was detectable were restricted to a small area, and were at a distance of 14 +/- 4 mm from the TE. The direction of the FP site from the TE was more basal in two patients and inferior in one. Pacemap ECGs at the sites with an FP showed poor matching (9 +/- 1 points), presumably because of predominant capture of the local ventricular muscle rather than an electrically isolated reentry circuit. Successful RFCA was achieved at the site of the FP in all three patients in which one was recorded, and at the TE in the other six patients. The FP, which has been shown to reflect the slow conduction of the ventricular tachycardia circuit in structural heart disease, was also detected in ILVT in the present study, and it is likely to reflect electrical excitation of the distal rim of the slow conduction zone.

Action Potentials↗
PubMed1999

N-Nitrosodi-n-propylamine induces organ specific mutagenesis with specific expression times in lacZ transgenic mice.

The mutagenic and clastogenic effects of N-nitrosodi-n-propylamine (NDPA) in lacZ transgenic mice (MutaMouse) were investigated as a part of the second collaborative study of the transgenic mouse mutation assay by a subgroup of the Mammalian Mutagenesis Study Group, a suborganization of the Environmental Mutagen Society of Japan. Male MutaMouse mice were administered NDPA intraperitoneally at a dose of 250 mg/kg, which is half of the LD(50) of the compound. The clastogenicity of NDPA was examined by the peripheral blood micronucleus test just before and at 24, 48 and 72 h after the treatment. The mutant frequencies in the bone marrow, liver, lung, kidney and urinary bladder were examined by the positive selection method for lacZ kidney. These findings demonstrate that NDPA induces organ-specific mutagenesis with specific expression times, and that the mutagenicity of NDPA in lacZ transgenic mice is consistent with its carcinogenicity.

Animals↗
PubMed1999

Cloning of differentially expressed genes in highly and low metastatic rat osteosarcomas by a modified cDNA-AFLP method.

To identify differentially expressed genes between highly and low metastatic rat transplantable osteosarcomas, we applied a modified AFLP (amplified fragment length polymorphisms) method for cDNA subtraction. The specific point of our modification is selective amplification using suppression PCR technique after restriction enzyme cutting. Our cDNA-AFLP gave high reproducibility (about 95%) in mRNA patterns and enabled us to clone four dominantly expressed genes in a highly metastatic tumor line. Three showed homology with known genes, encoding Ki-67, a proliferation-associated effective marker of malignancy, type IV collagen alpha-3, a major component of basement membrane, and KIAA77 for which the function is unknown. Although one fragment showed no database homology, we revealed a derivation from the rat homologue of the Drosophila melanogaster diaphanous gene (Dia) by cloning of longer cDNA. Dia genes, known to affect actin filament formation, are downstream effectors of Rho small GTPase. The results suggest that alterations in the expression of cytoskeletal protein, basement membrane elements, and proliferative markers may be important for metastasis of osteosarcomas.

Amino Acid Sequence↗
PubMed1999

Delay in administration of CDDP until completion of AGM-1470 treatment enhances antimetastatic and antitumor effects.

The efficacy of cis-diammine dichloroplatinum (CDDP) therapy in combination with continuous administration of angiogenesis inhibitor o-(chloroacetyl-carbamoyl) fumagillol (AGM-1470) was evaluated experimentally using a transplantable rat osteosarcoma line previously established in our laboratory. AGM-1470 (2.5 mg/kg body weight/week) was administered by Alzet osmotic pumps for 2 weeks starting from 7 days after tumor inplantation and CDDP (1.25 mg/kg) was given on days 21 and 24. The number of lung metastatic nodules was counted and the wet weights of the primary tumors were measured 5 weeks after tumor inplantation. Values with administration of CDDP 3 days after discontinuation of AGM-1470 were significantly lower than when the two agents were coadministered (P < 0.05). This animal model should facilitate optimization of the timing of combination therapy.

Animals↗