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Biomedical subjects

K Obara

Publications and source records attributed to K Obara.

At least 55 records · Page 3Linked to original sources
PubMed2000

Adherence of cyanoacrylate which leaked from gastric varices to the left renal vein during endoscopic injection sclerotherapy: a histopathologic study.

We report a case involving leakage of cyanoacrylate (CA) to the inferior vena cava (IVC) through a gastrorenal shunt and left renal vein. A 72-year-old man with liver cirrhosis was admitted to our hospital to undergo emergency treatment for massive hemorrhage of gastric varices. Endoscopic injection sclerotherapy (EIS) using CA was performed on the varices. Radiographic fluoroscopy revealed that most of the injected CA had adhered firmly to the gastric varices, but a certain portion of the CA had flowed to the IVC through the gastrorenal shunt and left renal vein. At that point, the patient did not complain of any symptoms. However, 6 months later, he died of hepatic failure and an autopsy was performed. Histopathologic examination of the wall of the IVC and renal vein, to which CA had adhered, revealed that the CA was covered with endothelial cells of the vessel and no nearby thrombus was present. Long-term anticoagulant therapy may not be indicated in cases of leakage of CA from the gastric varices to other veins, since the leaked CA may be readily covered with endothelium without thrombus formation as in our patient. It is possible for CA to flow to the IVC and have a fatal impact. Our patient was fortunate, and for safe EIS it is important that these complications are prevented.

Aged↗
PubMed2000

Protein kinase C delta but not PKC epsilon activity is involved in contractile potentiation by endothelin-1 in the porcine coronary artery.

To clarify the mechanism of contractile strengthening by endothelin-1 (ET-1), we measured translocation of protein kinase C (PKC) from the cytosol to the membrane fraction in the porcine coronary artery. ET-1 potentiated the serotonin- (5-hydroxytryptamine, 5-HT) induced contraction without any additional increase in myosin light chain phosphorylation. Four PKC isoforms (alpha, beta1, delta, and zeta) were identified but not PKC epsilon. Only PKC delta was translocated from the cytosolic to the membrane fraction during the contractile potentiation by ET-1. Our results suggest that the activity of PKC delta but not PKC epsilon is involved in the contractile strengthening by ET-1 in the porcine coronary artery.

Animals↗
PubMed2000

Effects of microtubules and microfilaments on [Ca(2+)](i) and contractility in a reconstituted fibroblast fiber.

We used a reconstituted fiber formed when 3T3 fibroblasts are grown in collagen to characterize nonmuscle contractility and Ca(2+) signaling. Calf serum (CS) and thrombin elicited reversible contractures repeatable for >8 h. CS elicited dose-dependent increases in isometric force; 30% produced the largest forces of 106 +/- 12 microN (n = 30), which is estimated to be 0.5 mN/mm(2) cell cross-sectional area. Half times for contraction and relaxation were 4.7 +/- 0.3 and 3.1 +/- 0.3 min at 37 degrees C. With imposition of constant shortening velocities, force declined with time, yielding time-dependent force-velocity relations. Forces at 5 s fit the hyperbolic Hill equation; maximum velocity (V(max)) was 0.035 +/- 0. 002 L(o)/s. Compliance averaged 0.0076 +/- 0.0006 L(o)/F(o). Disruption of microtubules with nocodazole in a CS-contracted fiber had no net effects on force, V(max), or stiffness; force increased in 8, but decreased in 13, fibers. Nocodazole did not affect baseline intracellular Ca(2+) concentration ([Ca(2+)](i)) but reduced ( approximately 30%) the [Ca(2+)](i) response to CS. The force after nocodazole treatment was the primary determinant of stiffness and V(max), suggesting that microtubules were not a major component of fiber internal mechanical resistance. Cytochalasin D had major inhibitory effects on all contractile parameters measured but little effect on [Ca(2+)](i).

3T3 Cells↗
PubMed2000

Expression of the ET(A) and ET(B) endothelin receptor subtype mRNA in human detrusor cultured smooth muscle cells.

The aim of this study was to determine the expression of the endothelin receptor subtype mRNAs in human detrusor cultured smooth muscle cells using reverse transcription-polymerase chain reaction (RT-PCR) and in situ hybridization (ISH). First strand cDNA was made from human detrusor cultured smooth muscle cells total RNA and used for PCR with primers designed to amplify fragments of the ET(A) and ET(B) endothelin receptor subtype cDNA sequences. Subcloned fragments of the ET(A) and ET(B) endothelin receptor cDNAs were used to synthesize digoxigenin-labeled cRNA probes by in vitro transcription. COS-7 cells transfected with the ET(A) and ET(B) receptor cDNAs were used as positive control and to confirm the absence of cross-hybridization due to sequence homology. Both ET(A) and ET(B) receptor mRNAs were detected by RT-PCR analysis. By ISH, both ET(A) and ET(B) receptor subtype mRNAs were detected. However, ET(A) signal was much more intense than ET(B) signal. These results indicate that mRNAs for both ET(A) and ET(B) receptors are expressed in detrusor smooth muscle cells of human urinary bladder. The ET(A) receptor is the predominant detrusor ET receptor.

Cells, Cultured↗
PubMed2000

Addition of antibacterial agents to MMA-TBB dentin bonding systems--influence on tensile bond strength and antibacterial effect.

To produce a bonding system which has both high bond strength and antibacterial properties, an antibacterial agent (vancomycin: VCM or metronidazol: MN) was added to the PMMA powder of 4-META/MMA-TBB resin (CB). The influence of the addition of an antibacterial agent on tensile bond strength to dentin and the antibacterial effect were investigated in this study. Forty-seven freshly extracted bovine first or second incisors were used to measure the tensile bond strength to dentin. The bond strengths to bovine dentin were not significantly decreased by addition of VCM (1%, 2%, 5%), or MN (1%) to CB (p < 0.05). The antibacterial effect of CB containing antibacterial agent on six strains of bacteria was investigated by the agar plate diffusion method, analyzing the appearance of the inhibition zone around a resin disk following anaerobic culturing. The resin disks containing VCM showed antibacterial effects on all of the strains examined; the widths of the inhibition zones were 4-15 mm. The resin disks containing MN showed antibacterial effects on three strains; the widths of the inhibition zones were 0-4 mm. It was thus possible to produce a bonding system with both antibacterial effect and high tensile bond strength by addition of VCM to PMMA powder.

Acrylic Resins↗
PubMed2000

Local cerebral hemodynamic changes through the angiographic stages of moyamoya disease.

In order to elucidate the cerebral hemodynamic changes that occur in Suzuki's six angiographic stages of moyamoya disease, local cerebral blood flow (LCBF) during the stable state and CO2 responsiveness of LCBF (L-CO2R: delta %LCBF/delta PaCO2) were measured by the Xenon CT-CBF method. Nineteen patients with moyamoya disease (mean age: 36.8 +/- 11.6 years) and 11 age-matched normal volunteers were studied. The LCBF during the steady state at all stages was not significantly different from that in normal volunteers. At stage 6, however, the LCBF was slightly decreased in the anterior part of the brain, resulting in loss of "hyperfrontality." On the other hand, the L-CO2R in the anterior part of the brain tended to diminish with progression through the stages. Especially in the frontal cortex, the L-CO2R at stage 5 was significantly less than that in normal volunteers (p < 0.01) or at stage 3 (p < 0.05). In conclusion, the cerebrovascular reserve in the anterior circulation became insufficient after stage 4, although the posterior circulation was well maintained. Revascularization surgery involving the anterior circulation may be crucial to prevent ischemic events.

Adult↗
PubMed2000

[Diffusion-weighted magnetic resonance imaging of neuro-Behçet's disease].

We report 2 patients (35-year-old and 38-year-old men) with neuro-Behçet's disease and characterize their diffusion-weighted MRI (DWI) findings of brain. T2-weighted and fluid-attenuated inversion recovery images obtained during the acute phase of neurological manifestations demonstrated multiple hyperintense lesions with a characteristic distribution in the brain including brainstem, thalamus, basal ganglia, and cerebral hemisphere. Most of these lesions did not exhibit increased signal intensity on DWI. This MRI profile, especially the combination of isointensity on DWI and hyperintensity on T2-weighted image, of neuro-Behçet's disease is similar to that of multiple sclerosis, and different from that of acute cerebral infarction and herpes simplex encephalitis.

Acute-Phase Reaction↗
PubMed1999

EUS analysis of collateral veins inside and outside the esophageal wall in portal hypertension.

BACKGROUND: The relation between esophageal varices and venous collaterals outside the esophageal wall in patients with portal hypertension remains unclear. We investigated this relationship with endoscopy and endoscopic ultrasound (US). METHODS: Twenty-two patients with untreated varices were examined. The collaterals were studied with a 20 MHz US catheter probe. Collaterals were divided into two groups: (1) periesophageal collateral veins adjacent to the muscularis externa of the esophagus and (2) paraesophageal collateral veins external to the esophageal wall but without contact with the muscularis externa. Periesophageal and paraesophageal collateral veins were scored as mild or severe according to stage of development. RESULTS: Varix form as defined endoscopically was significantly larger in the severe periesophageal collateral veins group than in the mild periesophageal collateral veins group (p < 0. 01). In contrast, varix form did not differ significantly between the mild and severe paraesophageal collateral veins groups. Perforating veins were detected in the distal esophagus in 18 of 22 patients (81.8%) by means of US. The prevalence of perforating veins increased in relation to varix form. Two types of perforating veins were found on the basis of connection with periesophageal and paraesophageal collateral veins. The frequency with which perforating veins were connected to periesophageal collateral veins was 81.8%; the frequency of connection to paraesophageal collateral veins was 27.3%. CONCLUSION: Periesophageal collateral veins play a more important role in the formation of esophageal varices than do paraesophageal collateral veins.

Adult↗
PubMed1999

alpha1- and alpha2-adrenoceptors in BPH.

The dynamic obstruction of the bladder outlet secondary to benign prostatic hyperplasia (BPH), and the contractile properties of the human prostate are mediated primarily by alpha1-adrenoceptors. There are now at least three subtypes (A, B, and D) of alpha1-adrenoceptors, and recent work revealed that alpha1A-adrenoceptor and alpha1B-adrenoceptor may have a prime role for prostatic obstruction, and contraction of artery, respectively. Very recently, the presence of a low affinity alpha1-adrenoceptor for prazosin, named alpha1L, in the human BPH tissue has been determined. Because the DNA sequence of alpha1L-adrenoceptor has not yet been cloned, the alpha1L-adrenoceptor may be another form of the alpha1A-adrenoceptor, or another pharmacologically distinct alpha1-adrenoceptor which mediates the norepinephrine-induced contraction of the prostatic smooth muscle. Furthermore, the contribution of alpha1-adrenoceptors in the prostate to symptoms (not only obstructive, but irritative symptoms) which are elicited by prostatic obstruction remains to be determined.

Adrenergic alpha-Antagonists↗
PubMed1999

Contractile potentiation by endothelin-1 involves protein kinase C-delta activity in the porcine coronary artery.

The relationship between potentiation of serotonin (5-hydroxytryptamine, 5-HT)-induced contraction by endothelin-1 (ET-1) and the activity of protein kinase C (PKC) was examined in the porcine coronary artery. Low concentrations (30-100 pM) of ET-1 selectively potentiated the 5-HT-induced contraction 1.5 to 2 times over the control without any additional increase in myosin light-chain phosphorylation. The potentiation was attenuated by PKC down-regulation caused by phorbol 12-myristate 13-acetate. By Western blot analysis with isoform-specific antibodies to PKC, at least four isoforms (PKCalpha, PKCbeta1, PKCdelta and PKCzeta) were identified in the porcine coronary artery. PKCalpha and PKCdelta were mostly in the cytosol fraction, whereas PKCbeta1 and PKCzeta were almost equally distributed in the cytosol and membrane fractions in the resting and contractile states. Of the four isoforms, only PKCdelta was translocated from the cytosol to the membrane fraction during the contractile potentiation by ET-1. These results suggest that the activity of PKCdelta, a Ca2+-independent PKC isoform, is involved in the potentiation of 5-HT-induced contraction by ET-1 in the porcine coronary artery.

Animals↗
PubMed1999

Evidence for beta3-adrenoceptor subtypes in relaxation of the human urinary bladder detrusor: analysis by molecular biological and pharmacological methods.

The purpose of the present study was to confirm the presence of beta3-adrenoceptor subtype in the relaxation of human urinary bladder detrusor tissue by reverse transcription-polymerase chain reaction (PCR); direct sequencing of the PCR product, in situ hybridization; and isometric contraction. Using reverse transcription-PCR, the mRNAs of three receptor subtypes (beta1, beta2, and beta3) were expressed in the human urinary bladder detrusor tissue. Direct sequencing of the PCR product of the above beta3-adrenoceptor revealed no mutation in the amplified regions. In situ hybridization with digoxygenin-labeled oligonucleotide probe revealed the presence of the mRNA of beta3-adrenoceptor subtype in the smooth muscle of the urinary bladder. The relaxant effects of isoproterenol (a nonselective beta-adrenoceptor agonist); ZD7114, BRL37344, and CGP12177A (putative selective beta3-adrenoceptor agonists); and SR59230A (a putative selective beta3-adrenoceptor antagonist) were tested using an isometric contraction technique. Isoproterenol in either the presence or absence of both atenolol (a beta1-adrenoceptor-selective antagonist) and butoxamine (a beta2-adrenoceptor-selective antagonist) revealed a relaxant effect on the carbachol-induced contraction of the human urinary bladder detrusor. Both BRL37344 and CGP12177A also revealed relaxant effects on the human urinary bladder detrusor, but ZD7114 did not elicit any relaxation. These results suggest that beta3-adrenoceptor may have some role in urine storage in the human urinary bladder.

Adrenergic beta-Agonists↗
PubMed1999

Pharmacological and molecular biological evidence for ETA endothelin receptor subtype mediating mechanical responses in the detrusor smooth muscle of the human urinary bladder.

The aim of this study was to characterize endothelin receptor subtypes of the detrusor muscle of the human urinary bladder. The receptor subtypes mediating endothelin (ET)-1-induced activity in the human detrusor smooth muscles have been characterized using isometric contraction and reverse transcription-polymerase chain reaction (RT-PCR). ET-1 (a non-selective ET receptor agonist; 10(-10) M to 10(-6) M) exhibited concentration-dependent contractions in human urinary bladder with a plateau at concentrations above 3x10(-7) M. Neither IRL1620 nor sarafotoxin S6c (both ETB-selective agonists; 10(-10) M to 10(-6) M) elicited contractile activity in the human urinary bladder detrusor smooth muscle. FR139317 (an ETA-selective antagonist; 10(-7) M to 10(-5) M) produced a marked shift to the right of the ET-1 concentration-response curve in human urinary bladder detrusor smooth muscle (from the Schild plot TpA2=7.96; slope=0.95). In contrast, RES701-1 (an ETB-selective antagonist; 10(-7) M to 10(-5) M) had no effect on the ET-1 concentration-response curve. RT-PCR revealed positive amplification of ETA receptor mRNA fragment, but not ETB. These results indicate that the ET-1-induced contractile effects of urinary bladder detrusor smooth muscle seem to be mediated mainly by the ETA receptor, not by the ETB receptor.

Aged↗
PubMed1998

Analysis of peripheral blood mononuclear cell stimulated with pyruvate dehydrogenase complex, T-cell receptors from patients with primary biliary cirrhosis.

Progressive destruction of the intrahepatic bile ducts in patients with primary biliary cirrhosis (PBC) is thought to be mediated by cytotoxic T cells which recognize certain epitopes, such as the pyruvate dehydrogenase complex (PDC). To clarify the T-cell repertoire in PBC, we analyzed T-cell receptor (TCR) Vbeta-chain messages expressed in peripheral blood mononuclear cells (PBMCs) stimulated with PDC and in liver biopsy specimens. PBMCs from 12 PBC patients and 6 healthy controls were examined. The TCR Vbeta repertoires of unstimulated PBMCs and PBMCs stimulated with PDC purified from bovine heart were analyzed, using the reverse transcriptase-polymerase chain reaction (RT-PCR) and single-strand conformation polymorphism (SSCP). Liver biopsy specimens from 5 PBC patients were also analyzed. In the PBC patients, several different T-cell clones, some of which showed the same mobility, were evident in both the PDC-stimulated and unstimulated PBMCs, as demonstrated by SSCP analysis. In addition, TCR clonality of infiltrating lymphocytes in the liver was also observed in PBC patients, showing common clonal T-cell accumulation with that seen in PBMCs stimulated with PDC. These data indicate that common clonal T-cell accumulation specific for PDC may be present in both peripheral PBMCs and the liver of patients with PBC.

Case-Control Studies↗
PubMed1998

A case with subcapsular hematoma of the liver following laparoscopic cholecystectomy.

Laparoscopic cholecystectomy (LC) is a safe and less traumatic procedure for benign cholecystic disease. However there have been some complications peculiar to LC. Here we report a case with postoperative subcapsular hematoma of the liver after LC. A 78-year-old woman was admitted with acute cholecystitis due to cholecystolithiasis. She underwent LC and liver dysfunction was noted after the operation. Ultrasonography (US) and computed tomography (CT) showed subcapsular hematoma of the liver. It was supposed that it had happened to occur during the operation, but we could not make the cause clear. The patient was improved with only conservative therapy and discharged. It is important to handle the forceps carefully close to the liver in the laparoscopic surgery in order to prevent this complication. We report a case with subcapsular hematoma of the liver following LC with a review of the literature.

Aged↗
PubMed1998

Localization of P2Y1 purinoceptor transcripts in the rat penis and urinary bladder.

PURPOSE: The aim of this study was to determine the expression and localization of the P2Y1 purinoceptor mRNA in rat penis and urinary bladder using reverse transcription polymerase chain reaction (RT-PCR), northern blotting and in situ hybridization (ISH). MATERIALS AND METHODS: RT-PCR: First strand cDNA was prepared from rat penis and urinary bladder dome total RNA and used for PCR with primers designed to amplify fragments of the P2Y1 purinoceptor cDNA sequence. Northern blotting: PCR products were subcloned into the pGEM-5Zf(+) plasmid vector, sequenced and random primer labeled using 32p. Labeled probe was hybridized. ISH: Digoxigenin labeled cRNA probes were synthesized by in vitro transcription. RESULTS: P2Y1 purinoceptor mRNA was detected by RT-PCR analysis in both rat penis and urinary bladder. RNA blotting using a P2Y1 purinoceptor cDNA probe revealed a single transcript of 4.2kb in both tissues. This band was the same size as that expressed by the heart, which contains high levels of P2Y1 purinoceptor (Burnstock, G.: Physiological and pathological roles of purines: an update. Drug. Dev. Res., 28: 195, 1993). By ISH, P2Y1 purinoceptor mRNA was localized in detrusor smooth muscle cells and blood vessels in urinary bladder. In penis, positive signals were detected in endothelial cells which line the lacunar space and blood vessels. No hybridization was seen in corpus cavernosum smooth muscle cells and urethra. CONCLUSION: These results indicate that mRNAs for P2Y1 purinoceptor are expressed in detrusor smooth muscle cells and blood vessels of rat urinary bladder. However, in penis, this receptor is expressed in endothelial cells which lines the lacunar space and blood vessels, but not expressed in corpus cavernosum smooth muscle cells and urethra.

Animals↗
PubMed1997

Effects of hypoxia on [Ca2+]i, pHi and myosin light chain phosphorylation in guinea-pig taenia caeci.

1. Hypoxia (achieved by bubbling with N2 instead of O2) reduces the force of a KCl (40 mM)-induced contracture to approximately 10% of the control value in guinea-pig taenia caeci. The underlying mechanism of this relaxation in response to hypoxia was investigated by measuring the major cell signalling parameters, intracellular Ca2+ concentration ([Ca2+]i) and myosin regulatory light chain (LC20) phosphorylation (MLC-P1), as well as intracellular pH (pHi), a factor often suggested to mediate hypoxic relaxation of muscle. 2. [Ca2+]i, measured using the ratiometric fluorescent dye fura-2, increased when 40 mM KCl was added to physiological saline solution (PSS) (peak value assigned 100%), and the steady state after 15 min was 92.8%. There were no detectable decreases in [Ca2+]i during hypoxia. 3. MLC-Pi, measured using isoelectric focusing-polyacrylamide gel electrophoresis and identified using Western blotting, increased from 9% of the total LC20 in Ca(2+)-free PSS to a peak value of 51% in 40 mM KCl-PSS. The steady-state value in hypoxia of 43% was not significantly different from that in control oxygenated conditions at the same point in time. 4. pHi, measured using the ratiometric fluorescent dye 2',7'-bis(carboxyethyl)-5(6)-carboxy-fluorescein (BCECF), under quiescent conditions (Ca(2+)-free PSS) was 7.23 and increased to 7.36 with 40 mM KCl. After imposition of hypoxia pHi remained unchanged despite the known increase in both lactate content and production. 5. As [Ca2+]i and MLC-Pi, key factors in activation, were not decreased by hypoxia and changes in pHi were minor, hypoxic relaxation in guinea-pig taenia caeci appears to be directly related to energy limitation rather than any oxygen-sensing mechanism.

Animals↗
PubMed1997

Plasma endothelin-1 level in patients with renovascular hypertension - does the kidney with stenosis of the renal artery upregulate production of endthelin-1?

PROBLEM: To examine the value of plasma endothelin-1 (ET-1), we measured the level of plasma ET-1 activity of peripheral venous blood and selective renal venous blood in renovascular hypertension patients, and compared that activity with corresponding renin activity and split renal function. METHODS: ET-1 level, renin activity in selective renal venous blood and peripheral venous blood, and 99mTc-dimercaptosuccinic acid renal uptake as a split renal function test were measured in 11 patients (mean 42.1 years old) with renovascular hypertension (RVH) and 6 patients with both renal cell cancer (RCC) and essential hypertension. RESULTS: 1. In patients with RVH, resting peripheral venous plasma ET-1 ranged from 0.6 to 8.1 (mean 4.07) pg/ml and was higher than the normal level (p <0.01). However, the renal vein ET-1 ratio was nor correlated with the renal vein renin ratio. 2. In patients with RCC, resting peripheral venous plasma ET-1 was not different from the normal level. There was no step-up of plasma ET-1, or renin among renal veins, or the proximal and distal parts of the interior vena cava. 3. Both renal vein renin ratio and renal vein ET-1 ratios were inversely correlated with t99mTC-dimercaptosuccinic acid renal uptake as a split renal function examination in patients with RVH. 4. The peripheral plasma ET-1 level was correlated with the degree of stenosis of the renal artery in patients with RVH of a unilateral lesion, but not bilateral lesions. CONCLUSION: These results suggest that ET-1 may take part in the hypertensive mechanisms of RVH in addition to the renin-angiotensin system, but its significance in RVH still remains to be examined.

Adolescent↗