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Biomedical subjects

Y Miyauchi

Publications and source records attributed to Y Miyauchi.

At least 37 records · Page 2Linked to original sources
PubMed1999

Expression of growth factors after the release of ureteral obstruction in the rat kidney.

BACKGROUND: Little is known about the mechanisms underlying recovery from hydronephrosis. Using a rat kidney model, we investigated the possible contribution of growth factors during regeneration after hydronephrosis. METHODS: After the unilateral ureteral obstruction for 7 days, the obstruction was released by ureterocystostomy. Epidermal growth factor (EGF), hepatocyte growth factor (HGF) and transforming growth factor-beta1 (TGF-beta1) were studied using immunohistochemistry and semiquantitative reverse transcriptase-polymerase chain reaction (RT-PCR). RESULTS: The immunoreaction of EGF in the medulla of both obstructed and contralateral kidneys increased after releasing the obstruction. The release of ureteral obstruction brought further increased immunoreaction of HGF to both the cortex and the medulla of the contralateral kidney. The immunoreaction of TGF-beta1 also increased in the interstitium especially around the blood vessels in the post-obstructed kidney. The expression of HGF and EGF mRNA in both kidneys and TGF-beta1 mRNA in the obstructed kidney were increased after releasing the obstruction. CONCLUSIONS: These results suggest that various growth factors may be involved in the post-obstructive tubular recovery and interstitial damage in the rat kidney.

Animals↗
PubMed1999

Local slow potential preceding the surface QRS complex detected at the subvalvular mitral annulus in patients with a left-sided concealed accessory pathway. Incidence, electrophysiological characteristics and the possible mechanism, with demonstration of anterograde concealed conduction through the pathway.

AIM: We sought to evaluate the incidence and electrophysiological features of the local slow potential preceding the surface QRS complex (pre-QRS potential) which was detected more frequently at successful sites of catheter ablation of left parietal concealed accessory pathways, than at unsuccessful sites. METHODS AND RESULTS: Thirty eight consecutive patients with a single left sided concealed accessory pathway underwent radiofrequency catheter ablation exclusively from the subvalvular mitral annulus. The local bipolar electrograms during sinus rhythm from the target sites were carefully analysed and the incidence of pre-QRS potentials was compared between successful and unsuccessful ablation sites. All ablation sessions attained a successful outcome with a total of 84 radiofrequency current applications (38 at successful sites, 46 at unsuccessful sites). The incidence of pre-QRS potentials (preceding by 10 ms or more) was 12/38 at successful sites (32%) and 1/46 at unsuccessful sites (2%) (P<0.001). The QV interval, defined as the interval between the upstroke of the QRS complex and the ventricular electrogram, including the pre-QRS potential, was -5.6+/-9.1 ms at successful sites, while it was 1.2+/-6.1 ms at unsuccessful sites (P<0.001). The pre-QRS potential disappeared during atrioventricular reciprocating tachycardia and right ventricular pacing, and was eliminated by successful ablation. CONCLUSIONS: Detection of the pre-QRS potential was clinically relevant and could be distinguished from artifact. This potential may be caused by anterograde concealed conduction through the accessory pathways.

Atrioventricular Node↗
PubMed1999

Expression and molecular cloning of human liver leukotriene B4 omega-hydroxylase (CYP4F2) gene.

Human liver leukotriene B4 (LTB4) omega-hydroxylase (CYP4F2) plays an important role in the metabolic inactivation and degradation of LTB4, a potent mediator of inflammation. The regulatory mechanism for the transcription of CYP4F2 has not yet been clarified. Here, we report that CYP4F2 is constitutively expressed in a human hepatoma cell line, HepG2, and is not induced by clofibrate. We isolated the gene encoding CYP4F2 and determined its genomic organization and the functional activity of its promoters. The CYP4F2 gene contains at least 13 exons with its open reading frame being encoded from exon II to exon XIII. Exon I includes 49 bp of a 5' untranslated sequence. The structure of this gene is very similar to that of the CYP4F3 gene earlier reported by Kikuta et al. (DNA Cell Biol 1998;17:221-230). The 5' flanking sequence downstream from -165 of the CYP4F2 gene has 75% similarity to the corresponding region of the CYP4F3 gene. However, common putative regulating elements in the two human CYP4F genes were not detected except for the TATA box. The elements recognized by nuclear receptors were not observed within its 5' flanking region. Deletion of the 5' flanking regions containing putative regulating elements recognized by HNF-3beta, CDP CR, and p300 caused alterations in the transcriptional activity. The region from -83 to -67 was necessary for transcription, but the TATA sequence was not. Our results indicate that the human two CYP4F genes evolved by duplication and alterations of the transcription regulation region and the site of exon III.

Amino Acid Sequence↗
PubMed1999

Uncommon atrial flutter originating in the left atrioventricular groove: emergence after successful catheter ablation for a left concealed accessory pathway.

This report describes a 49-year-old male with concealed Wolff-Parkinson-White syndrome in whom a true uncommon atrial flutter suddenly emerged 2 weeks after successful catheter ablation of a left-sided accessory pathway. The earliest atrial activation during the atrial flutter was recorded at the posterolateral mitral annulus 2 cm proximal to the previous successful ablation site for the accessory pathway. Two applications of radiofrequency (RF) current directed at the supravalvular mitral annulus could not terminate the atrial flutter. A subsequent delivery of RF current directed at the subvalvular annulus, where a local fragmented potential preceded the earliest atrial activation, eliminated the atrial flutter.

Animals↗
PubMed1999

Incidence and clinical significance of junctional rhythm remaining after termination of radiofrequency current delivery in patients with atrioventricular nodal reentrant tachycardia.

The aim of this study was to elucidate the electrophysiologic characteristics and clinical significance of the accelerated junctional rhythm (JR) that remains after termination of radiofrequency (RF) current delivery during catheter ablation (CA) for atrioventricular nodal reentrant tachycardia (AVNRT). Fifty consecutive patients with AVNRT (21M, 29F, age 48 years) underwent RF-CA targeting the slow pathway. JR occurred at 124 out of a total of 236 ablation sites (53%) during the RF delivery. With 15 RF deliveries (6.4%, n=10), JR remained after termination of the RF delivery (Post-JR). The mean cycle length of the Post-JR immediately after termination of the RF delivery was 639+/-124 ms and its duration was widely distributed from 3 s to more than 1 h. The Post-JR exhibited a spontaneous rate deceleration and overdrive suppression by rapid atrial pacing. The JR during the RF delivery followed by Post-JR had a greater time span in which the JR appeared, compared with that without Post-JR. The Post-JR had less sensitivity(18 vs 96%), but greater specificity (97 vs 59%) and a positive predictive value (60 vs 39%) in predicting successful ablation compared with JR seen only during the RF delivery. It is concluded that the presence of Post-JR might be a reflection of the intense effect of RF energy on the nodal or peri-nodal tissue.

Adolescent↗
PubMed1999

[Surgical treatment of 2 cases of irradiation induced constrictive pericarditis].

A 72-years-old man underwent radiation therapy (62 Gy) for esophageal carcinoma. Twelve months later, symptoms of heart failure such as syncope, cough and hepatomegaly manifested. On catheter study, a dip and plateau pattern of right ventricular pressure curve was evident. Pericardiectomy without extracorporeal circulation was performed. Operative findings and pathological results were compatible with radiation-induced constrictive pericarditis. He recovered from the heart failure, and has been doing well 3 months after the surgery. A 54-years-old man underwent thymectomy for malignant thymoma. He underwent a radiation therapy (52 Gy) postoperatively. After 12 months from the irradiation, syncope and dyspnea manifested. On catheter study, a dip and plateau pattern of right ventricular pressure curve was observed. Pericardiectomy with extracorporeal circulation was performed. He recovered from the heart failure after pericardiectomy, however he died of radiation-induced pneumonitis 6 months later.

Aged↗
PubMed1999

[Postoperative sore throat and intracuff pressure: comparison among endotracheal intubation, laryngeal mask airway and cuffed oropharyngeal airway].

We studied which device is most useful to reduce postoperative sore-throat. We investigated the relationship between intracuff pressure and postoperative sore-throat in using endotracheal intubation (ET), the laryngeal mask airway (LMA) and the cuffed oropharyngeal airway (COPA) in adult patients. We classified sore-throat into categories; pain at rest, hoarseness and dysphasia. We evaluated pain at rest by the score (0: no pain, 1: mild discomfort, 2: mild pain, 3: severe pain). Pain at rest (scores 1, 2, 3) was complained by 10 patients in ET group, 3 in LMA group, 5 in COPA group on the day of operation, showing significantly lower incidence of pain at rest in LMA group than in ET group. Hoarseness was complained by 15 patients in ET group, 2 in LMA group and 4 in COPA group, showing significantly lower incidence of hoarseness in LMA and COPA groups than in ET group. Dysphasia was complained by 3 in ET group, 1 in LMA group and 2 in COPA group, showing no significant difference. These results suggest that LMA is most appropriate to reduce postoperative sore-throat.

Adult↗
PubMed1998

Inhibition of post-ischemic reperfusion injury of the kidney by diamine oxidase.

To elucidate the role of histamine in the pathogenesis of post-ischemic reperfusion injury of tissues, the effect of diamine oxidase (DAO) was studied on the changes in renal functions induced by 30 min occlusion followed by reperfusion of the renal vessels of unilaterally nephrectomized rats. Kinetic analysis using radiolabeled albumin revealed that vascular permeability of the kidney increased markedly after reperfusion. Although the intensity of neutrophil-dependent chemiluminescence of the blood remained unchanged during the occlusion, it increased significantly after reperfusion. Histological examination revealed a marked degeneration of glomeruli and proximal tubules in the reperfused kidney. Transtubular transport of phenolsulfophthalein (PSP) decreased markedly after reperfusion with concomitant increase in plasma levels of creatinine. Intravenously administered DAO markedly inhibited the reperfusion-induced increase in vascular permeability, preserved the structure of the kidney and normalized the rate of clearance of PSP and creatinine. Combined use of diphenylhydramine and ranitidine also inhibited the reperfusion injury of the kidney. These results suggested that histamine and its receptors might play critical roles in post-ischemic reperfusion injury of the kidney.

Amine Oxidase (Copper-Containing)↗
PubMed1998

Heterogeneous pattern of gene expression in cloned cell lines established from a rat transplantable osteosarcoma lung metastatic nodule.

We have established three cloned cell lines (COS1NR, COS2NR and COS4NR) from the lung metastatic nodule of a highly metastatic variant of rat transplantable osteosarcoma, C-SLM. All three clones shared the same morphological characteristics and tumorigenicity, but their growth rates in vitro and metastatic ability in vivo differed from each other. Single-strand conformation polymorphism (SSCP) analysis revealed all three clones to have the same p53 gene mutation and parent C-SLM tumor. On the other hand, Northern blot analysis showed a different pattern of expression for the genes, c-fos, c-jun, c-Ha-ras, transin (rat stromelysin), bone Gla protein (osteocalsin) and nm23/NDP kinase. These results indicate the presence of a heterogeneous cell population in terms of the different pattern of gene expression in a lung metastatic nodule of rat osteosarcoma and the present newly established cell lines will be useful for further investigation of the biological behavior of osteosarcomas.

Animals↗
PubMed1998

[A case of coronary artery bypass surgery using left internal thoracic artery and right gastroepiploic artery for a patient with essential thrombocythemia].

The 78-year-old male underwent coronary angiography because of angina pectoris. He was revealed to have essential thrombocythemia with a platelet count of over 1,000,000/mm3. Essential thrombocythemia belongs to the group of chronic myeloproliferative disorders. It displays both thrombogenic and bleeding tendency due to the increased platelet count, as well as to dysfunction. CABG was performed using the left internal thoracic artery and the right gastroepiploic artery. Hydroxycarbamide was taken to regulate the platelet count before surgery. There was no difficulty with hemostasis during surgery. Warfarin and hydroxycarbamide were used as anticoagulant therapies after surgery. Postoperative CAG demonstrated both grafts to be patients. The patient remained in good condition until he died suddenly on the 159th postoperative day. The cause of death was not clear because no autopsy was carried out. The death may have been associated with a thromboembolism, acute graft thrombosis or cerebral infarction, or pulmonary embolism. This patient did not take antiplatelet drugs because the platelet count and prothrombin time was well controlled. Nonetheless, an antiplatelet agent might reduce the risk of thromboembolism in such patients. It is suggested that meticulous anticoagulation therapy must be important for a patient with essential thrombocythemia, especially in the postoperative period.

Aged↗
PubMed1998

Human leukotriene B4 omega-hydroxylase (CYP4F3) gene: molecular cloning and chromosomal localization.

Leukotriene B4 (LTB4) omega-hydroxylase catalyzes the conversion of LTB4 into a biologically less active product, 20-hydroxy-LTB4. In a preceding paper (Kikuta et al., 1993), we showed human polymorphonuclear leukocyte (PMN) LTB4 omega-hydroxylase to be a novel form of cytochrome P450, designated CYP4F3, on the basis of its cDNA cloning and expression in yeast cells. Here, we have isolated the gene encoding CYP4F3 and determined its genomic organization and chromosomal localization. The CYP4F3 gene contained 13 exons and spanned approximately 22.2 kb. The cDNA of CYP4F3 contained 5050 nucleotides excluding the poly(A) tail. The translation initiation codon (ATG) was present in exon II. Primer extension and S1 mapping analyses indicated that the transcription initiation site is 49 nucleotides upstream from the 3' end of exon I, and no other initiation sites were detected. A TATA-box-like sequence (TACAT) and 120-b GC-rich sequence were observed just before transcription initiation site. Several putative regulating elements recognized by the GATA family, MZF-1, CACCC binding protein, and C/EBP, were identified in its 5' flanking region. Genomic DNA screening for CYP4F3 and Southern blot analysis suggested the existence of other CYP4F genes in addition to CYP4F3 and CYP4F2 in the human genome. Fluorescence in situ hybridization demonstrated that the CYP4F3 gene is located at 19p13.2.

Amino Acid Sequence↗
PubMed1998

Telomerase activity correlates with growth of transplantable osteosarcomas in rats treated with cis-diammine dichloroplatinum or the angiogenesis inhibitor AGM-1470.

To determine the role of telomerase activity in the growth of tumors in rats undergoing chemotherapy, a comparison of the volumes of telomerase-positive transplantable osteosarcomas was made in rats treated with the antineoplastic agent cis-diammine dichloroplatinum (CDDP) or the angiogenesis inhibitor O-(chloroacetylcarbamoyl)fumagillol (AGM-1470). Male F344 rats, 8 weeks old, received transplants of macroscopic lung metastatic nodules into the subcutaneous back space and treatment was started on day 14 thereafter. CDDP was injected i.v. at doses of 0, 0.625, 1.25 and 2.5 mg/kg body weight (b.w.) and AGM-1470 was administered at total doses of 0, 2.5, 5 and 10 mg/kg b.w. over 2 weeks by osmotic pumps, also implanted into the subcutaneous back space, but remote from the transplanted tumors. On day 28, all animals were killed for measurement of transplanted tumor size and determination of telomerase activities by telomeric repeat amplification protocol (TRAP) assay. The results showed telomerase activity to be highly correlated with the treated/non-treated (T/C) tumor size ratio (r = 0.96, P < 0.0001). In a second experiment, CDDP at 2.5 mg/kg b.w. and AGM-1470 at 10 mg/kg b.w., these being the most effective doses, were given as in the first experiment, and animals were serially killed on days 14, 21, 28, 35 and 42. Tumors in rats treated with CDDP and AGM-1470 showed 18.2% and 20.5% of the control telomerase activity on days 35 and 21, respectively, when tumor growth was inhibited. However, on day 42, the activities increased to 46.5% and 92.5%, this correlating with re-growth (r = 0.73, P < 0.0001). These results suggest that decline of telomerase activity may be involved in tumor growth retardation induced by chemotherapeutic agents. This possibility clearly warrants further mechanistic studies.

Animals↗
PubMed1998

Detection of a local slow potential preceding the surface QRS complex during non-preexcited impulse propagation--a phenomenon reflecting anterograde concealed conduction through the accessory pathway?

A case of Wolff-Parkinson-White (WPW) syndrome with several interesting electrophysiologic findings is presented. Although manifest preexcitation had not been documented in clinical routine check-ups for the 2 years before the ablation session, an intermittent preexcitation emerged after an initial unsuccessful radiofrequency current delivery directed at the subvalvular mitral annulus 1 cm distal from the subsequent successful ablation site. During intermittent manifestation of preexcitation, the following observations were made: (1) during manifest preexcitation, a possible Kent potential was recorded at the successful ablation site; (2) during non-preexcited impulse propagation, a local slow potential preceding the QRS complex (pre-QRS potential) was clearly observed at the same site; (3) the pre-QRS potential disappeared during orthodromic atrioventricular reciprocating tachycardia, spontaneous atrial premature contraction and after the subsequent successful ablation; and (4) when the pre-QRS potential was obvious, a small change in QRS morphology of the body-surface ECG was appreciable, compared with that during beats of negative pre-QRS potential. A comparable preceding component was also detected in a signal-averaged ECG. It is considered that the pre-QRS potential might be related to the anterograde concealed conduction through the accessory pathway.

Electrophysiology↗
PubMed1998

[Carbon monoxide concentrations during low flow anesthesia].

Elevated carbon monoxide (CO) concentrations have been reported during general anesthesia using inhaled anesthetics. In order to assess the safety of low flow anesthesia, we examined CO concentrations in anesthesia circuit during low flow anesthesia. Thirty patients were randomly divided into two groups. Anesthesia was induced with intravenous thiopental 5 mg.kg-1 and maintained with oxygen 2 l.min-1, nitrous oxide 4 l.min-1 and isoflurane (group H) or oxygen 0.5 l.min-1, nitrous oxide 0.5 l.min-1 and isoflurane (group L). The concentrations of CO in exhaust gas of anesthetic gas monitor were examined by CO sensor (XC-341, Shinkosumosudenki, Tokyo) and COHb was analyzed. The concentrations of CO in group L were significantly higher than in group H. The highest value, however, was 30 ppm. The COHb levels were slightly higher in group L, but the highest value was 2.1%. We consider that these results show no clinical risk and low flow isoflurane anesthesia may be performed safely. Measuring the CO concentrations is helpful for the safety of low flow anesthesia.

Aged↗
PubMed1998

[Bronchodilator aerosol propellant interferes with an photoacoustic spectrophotometer respiratory gas analyzer].

A patient with bronchial asthma was scheduled for an operation under nitrous oxide-isoflurane anesthesia. We monitored isoflurane concentrations continuously using an anesthetic gas analyzer (BK 1304). Upon puffing procaterol hydrochloride aerosol for 4 times, the analyzer showed a rapid increase in end-tidal isoflurane concentration. The BK 1304 uses infrared photoacoustic spectrophotometry and it is susceptible to interferences caused by Freon propellants in bronchodilator aerosols. We should take care in monitoring inhalational anesthetics when using aerosols containing Freon propellants.

Aerosols↗
PubMed1998

[Carbon monoxide in the expiratory gas during laparoscopic surgery].

One of the complications of laparoscopic surgery is carbon monoxide (CO) production under the use of electrocautery. We experienced a case in which high levels of CO were detected in the expiratory gas. An 80-year old, 33 kg female was scheduled for laparoscopic nephrectomy. Anesthesia was induced with thiopental and vecuronium and maintained with nitrous oxide 60% in oxygen and isoflurane. The concentrations of CO in the anesthetic circuit were examined with CO sensor (XC-341, Shinkosumosudenshi, Tokyo). The CO concentrations were not detected at the start of operation. About 140 minutes after carbon dioxide pneumoperitoneum, the CO concentration increased up to 170 ppm accompanying a high Paco level. The high concentrations, however, decreased immediately after ending of pneumoperitoneum. The HbCO levels were unchanged. Subcutaneous emphysema was noted at the end of surgery. This is because CO is more absorbable in the subcutaneous tissue than in the peritoneal cavity. We consider that CO was absorbed in subcutaneous emohysema during pneumoperitoneum and exhausted in the expiratory gas. When subcutaneous emphysema occurred during laparoscopic surgery, we should be aware of absorption of CO.

Aged↗
PubMed1997

Increased telomerase activity is not directly related to metastatic potential in rat transplantable osteosarcomas.

Previously, we reported the establishment of two transplantable osteosarcomas in rats, one induced by local application of a carcinogen, 4-hydroxyamino quinoline 1-oxide (4-HAQO), and another which developed spontaneously, and their subdivision into four lines with high and low metastatic potential to the lung. In the present study, activation of telomerase was investigated by the telomeric repeat amplification protocol (TRAP) assay followed by densitometric quantification. Telomerase activity was found to be elevated in all four lines without any link to the metastatic potential. Thus the spontaneous osteosarcoma (SOS) and derived metastatic lesions (S-SLM) demonstrated a 20.1-23.5-fold increase and the chemical carcinogen (4HAQO)-induced osteosarcoma (COS) and metastatic lesions (C-SLM) were 18.4-19.1-fold elevated as compared to the value for abdominal muscle. The results suggest that activation of telomerase occurs in rat osteosarcomas but that it is not directly involved in determining their metastatic potential.

Animals↗