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Biomedical subjects

S Matsuoka

Publications and source records attributed to S Matsuoka.

At least 19 recordsLinked to original sources
PubMed1992

A new bioabsorbable material for rat vascular cuff anatomosis: establishment for the long-term orthotopic liver transplantation model.

Rat vascular anastomosis was performed using a newly synthesized bioabsorbable material (LA-GA copolymer) cuffs and the ordinary polyethylene cuffs. The LA-GA copolymer cuff which anastomosed the portal vein and the inferior vena cava were patent and developed no collateral veins even after 6 months, keeping the transplanted liver normal. By contrast, the polyethylene cuff anastomosed portal vein was completely occluded and the collateral veins were highly developed, with the transplanted liver showing the fatty degeneration of hepatocytes and numerous regenerative nodules. It is concluded that the LA-GA copolymer cuff is a suitable material for the short and long term study of rat orthotopic liver transplantation.

Absorption↗
PubMed1992

Kawasaki-like disease in early course of acute monocytic leukaemia.

We report a rare occurrence of Kawasaki-like disease in an 11-year-old boy with acute monocytic leukaemia (AML). After 1 week of induction therapy with daunorubicin, etoposide, and cytosine arabinoside, the patient sequentially developed persistent fever, lymphadenopathy, conjunctival injection, exanthema, redness of the lips, and desquamation of the hands. Chest roentgenology showed cardiomegaly and an echocardiogram revealed a dilation of the left coronary artery. The patient was treated with high doses of gamma globulin and steroids. All symptoms except the coronary artery dilation improved. The symptoms did not recur on reinstatement of the original antileukaemia drugs.

Child↗
PubMed1992

Effect of a novel class I antiarrhythmic agent, TYB-3823, on the calcium current in single guinea pig ventricular myocytes.

The effect of TYB-3823 on Ca2+ current (ICa) of guinea pig ventricular myocytes was investigated by means of whole-cell patch-clamp technique. TYB-3823 (100-1,000 microM) caused a concentration-dependent decrease in ICa. Furthermore, a reduction of ICa induced by TYB-3823 (1,000 microM) was progressively accentuated by repetitive membrane depolarization, indicating a rate-dependent block of ICa. However, the inhibitory potency on ICa was approximately 1/1000 of a Ca2+ antagonistic agent, verapamil hydrochloride. Considering evidence that 3-30 microM TYB-3823 decreased the maximum upstroke velocity of the action potential of guinea pig ventricular muscles, it is indicated that the drug does not show its Ca2+ antagonistic property in the usual concentration range as a class I antiarrhythmic agent.

Animals↗
PubMed1992

Steady-state and dynamic properties of cardiac sodium-calcium exchange. Sodium-dependent inactivation.

Sodium-calcium exchange current was isolated in inside-out patches excised from guinea pig ventricular cells using the giant patch method. The outward exchange current decayed exponentially upon activation by cytoplasmic sodium (sodium-dependent inactivation). The kinetics and mechanism of the inactivation were studied. (a) The rate of inactivation and the peak current amplitude were both strongly temperature dependent (Q10 = 2.2). (b) An increase in cytoplasmic pH from 6.8 to 7.8 attenuated the current decay and shifted the apparent dissociation constant (Kd) of cytoplasmic calcium for secondary activation of the exchange current from 9.6 microM to < 0.3 microM. (c) The amplitude of exchange current decreased synchronously over the membrane potential range from -120 to 60 mV during the inactivation, indicating that voltage dependence of the exchanger did not change during the inactivation process. The voltage dependence of exchange current also did not change during secondary modulation by cytoplasmic calcium and activation by chymotrypsin. (d) In the presence of 150 mM extracellular sodium and 2 mM extracellular calcium, outward exchange current decayed similarly upon application of cytoplasmic sodium. Upon removal of cytoplasmic sodium in the presence of 2-5 microM cytoplasmic free calcium, the inward exchange current developed in two phases, a fast phase within the time course of solution changes, and a slow phase (tau approximately 4 s) indicative of recovery from sodium-dependent inactivation. (e) Under zero-trans conditions, the inward current was fully activated within solution switch times upon application of cytoplasmic calcium and did not decay. (f) The slow recovery phase of inward current upon removal of cytoplasmic sodium was also present under the zero-trans condition. (g) Sodium-dependent inactivation shows little or no dependence on membrane potential in guinea pig myocyte sarcolemma. (h) Sodium-dependent inactivation of outward current is attenuated in rate and extent as extracellular calcium is decreased. (i) Kinetics of the sodium-dependent inactivation and its dependence on major experimental variables are well described by a simple two-state inactivation model assuming one fully active and one fully inactive exchanger state, whereby the transition to the inactive state takes place from a fully sodium-loaded exchanger conformation with cytoplasmic orientation of binding sites (E1.3Ni).

Adenosine Triphosphate↗
PubMed1992

Steady-state and dynamic properties of cardiac sodium-calcium exchange. Secondary modulation by cytoplasmic calcium and ATP.

Dynamic responses of cardiac sodium-calcium exchange current to changes of cytoplasmic calcium and MgATP were monitored and analyzed in giant membrane patches excised from guinea pig myocytes. Secondary dependencies of exchange current on cytoplasmic calcium are accounted for in terms of two mechanisms: (a) The sodium-dependent inactivation process, termed I1 modulation, is itself strongly modulated by cytoplasmic calcium. Recovery from the I1 inactivated state is accelerated by increasing cytoplasmic calcium, and the calculated rate of entrance into I1 inactivation is slowed. (b) A second modulation process, termed I2 modulation, is not sodium dependent. As with I1 modulation, the entrance into I2 inactivation takes place over seconds in the absence of cytoplasmic calcium. The recovery from I2 inactivation is a calcium-dependent transition and is rapid (< 200 ms) in the presence of micromolar free calcium. I1 and I2 modulation can be treated as linear, independent processes to account for most exchange modulation patterns observed: (a) When cytoplasmic calcium is increased or decreased in the presence of high cytoplasmic sodium, outward exchange current turns on or off, respectively, on a time scale of multiple seconds. (b) When sodium is applied in the absence of cytoplasmic calcium, no outward current is activated. However, the full outward current is activated within solution switch time when cytoplasmic calcium is applied together with sodium. (c) The calcium dependence of peak outward current attained upon application of cytoplasmic sodium is shifted by approximately 1 log unit to lower concentrations from the calcium dependence of steady-state exchange current. (d) The time course of outward current decay upon decreasing cytoplasmic calcium becomes more rapid as calcium is reduced into the submicromolar range. (e) Under nearly all conditions, the time courses of current decay during application of cytoplasmic sodium and/or removal of cytoplasmic calcium are well fit by single exponentials. Both of the modulation processes are evidently affected by MgATP. Similar to the effects of cytoplasmic calcium, MgATP slows the entrance into I1 inactivation and accelerates the recovery from inactivation. MgATP additionally slows the decay of outward exchange current upon removal of cytoplasmic calcium by 2-10-fold, indicative of an effect on I2 inactivation. Finally, the effects of cytoplasmic calcium on sodium-calcium exchange current are reconstructed in simulations of the I1 and I2 modulation processes as independent reactions.

Adenosine Triphosphate↗
PubMed1992

Steady-state and dynamic properties of cardiac sodium-calcium exchange. Ion and voltage dependencies of the transport cycle.

Ion and voltage dependencies of sodium-calcium exchange current were studied in giant membrane patches from guinea pig ventricular cells after deregulation of the exchanger with chymotrypsin. (a) Under zero-trans conditions, the half-maximum concentration (Kh) of cytoplasmic calcium (Cai) for activation of the isolated inward exchange current decreased as the extracellular sodium (Nao) concentration was decreased. The Kh of cytoplasmic sodium (Nai) for activation of the isolated outward exchange current decreased as the extracellular calcium (Cao) concentration was decreased. (b) The current-voltage (I-V) relation of the outward exchange current with saturating concentrations of Nai and Cao had a shallow slope (twofold change in approximately 100 mV) and a slight saturation tendency at very positive potentials. The outward current gained in steepness as the Nai concentration was decreased, such that the Kh for Nai decreased with depolarization. The decrease of Kh for Nai with depolarization was well described by a Boltzmann equation (e alpha.Em/26.6) with a slope (alpha) of -0.06. (c) Voltage dependence of the outward current was lost as the Cao concentration was decreased, and the Kh for Cao increased upon depolarization with a Boltzmann slope of 0.26. (d) The I-V relation of the inward exchange current, under zero-trans conditions, was also almost linear (twofold change in approximately 100 mV) and showed some saturation tendency with hyperpolarization as the Cai concentration was decreased. The Kh for Cai decreased with depolarization (Boltzmann slope, -0.10). Voltage dependence of the inward current was decreased in the presence of a high (300 mM) Nao concentration. (e) In the presence of both Na and Ca on both membrane sides, the I-V relations with saturating Nai show sigmoidal shape and clear saturation at positive potentials. Measured reversal potentials were close to the equilibrium potential expected for a 3 Na to 1 Ca exchange. (f) Nai and Cai interacted competitively with respect to the outward current, but in a mixed competitive-noncompetitive fashion with respect to the inward current. (g) Cai inhibited the outward exchange current in a voltage-dependent manner. The half-effective concentration for inhibition (Ki) by Cai increased upon depolarization with a Boltzmann slope of 0.32 in 25 mM Nai and 0.20 in 100 mM Nai. (h) Nai also inhibited the inward exchange current voltage dependently. The Ki decreased upon depolarization (Boltzmann slope, -0.11 at 3 microM Cai and -0.10 at 1.08 mM Cai).(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1992

Activation of the mouse proliferating cell nuclear antigen gene promoter by adenovirus type 12 E1A proteins.

A plasmid carrying the 5'-flanking region (-1584 to +47 with respect to the transcription initiation site) of the mouse proliferating cell nuclear antigen (PCNA) gene was fused with the chloramphenicol acetyltransferase (CAT) gene, and then cotransfected into mouse N18TG2 cells with expression plasmids for the adenovirus type 12 E1 genes. Expression of E1A gene products elevated the CAT expression by 5- to 9-fold, but expression of the E1B gene product did not. RNase protection analysis revealed that the activation of the PCNA gene promoter by E1A was at the transcription step. Both the 13S E1A and the 12S E1A activated the PCNA gene promoter, indicating that the activation domain of E1A resides in a common region(s) of 13S and 12S E1A products. The major target region of E1A was mapped within the 68 base-pair region (-21 to +47) of the PCNA gene, which includes consensus sequences for transcription factors PEA3 and E2F, although the upstream region (-83 to -21) including ATF(CREB)-binding consensus had an additional effect in the transactivation.

Adenovirus Early Proteins↗
PubMed1992

Clinical significance of late potentials in patients after intracardiac operation for congenital heart disease.

The aim of this study was to evaluate the late potentials (LPs) in postoperative patients with congenital heart disease (CHD) and to study the association with the clinical characteristics in the postoperative patients with LPs. Signal averaged electrocardiogram (SA-ECG) was recorded in 119 postoperative patients aged 4 to 23 years and compared with those in age matched 49 healthy volunteers with and without right bundle branch block. Based on control data, criterias of LP were defined and altered in the presence of bundle branch block. Abnormal SA-ECGs were not detected in the patients with non-cyanotic CHD. However, abnormal and borderline SA-ECGs were recognized in 5 (12%) of 42 patients after intracardiac operation for tetralogy of Fallot and 3 (30%) of 9 patients after Rastelli's operation. The patients with abnormal and borderline SA-ECGs were significantly older at the time of operation, and had more frequent ventricular arrhythmias (7/8: 3/111, p less than 0.01) and depression of the ST-T segment on ECG (7/8: 11/111, p less than 0.01), compared with the normal SA-ECG group. Abnormal SA-ECGs including those of borderline patients were 50% sensitive and 96% specific for documented ventricular arrhythmias. However, there was no association between abnormalities of SA-ECGs and cardiomegaly on chest X-ray or left ventricular ejection fraction on echocardiogram. These results indicate that prolonged exposure to hypoxia may be the main cause of the primary role in the development of LPs. And late surgical intervention may result in histological background for the development of LPs.

Action Potentials↗
PubMed1992

Accessory middle cerebral artery and duplication of middle cerebral artery--terminology, incidence, vascular etiology, and developmental significance.

A series of 455 bilateral carotid angiographies included 14 accessory middle cerebral arteries (Acc-MCAs) and seven duplication of middle cerebral arteries (Dup-MCAs). The branching patterns of Dup-MCA could be classified as "direct bifurcation" from the internal carotid artery, since most lacked the essential bifurcation or trifurcation at the distal end of the M1 portion. On the other hand, Acc-MCAs are probably residual congenital arteries. These anomalous MCAs were apparently associated with epilepsy. Five Acc-MCAs were associated with anterior communicating artery aneurysm at the origin. In addition, a rare case of Dup-MCA with arteriovenous malformation at its origin was found.

Adolescent↗
PubMed1992

[Problem of the long-term arterial infusion therapy with implantable reservoir for unresectable hepatocellular carcinoma].

Arterial infusion therapy with implantable reservoir was performed for forty-seven cases with unresectable hepatocellular carcinoma since 1986-1991. The one-year survival rate of cases of arterial infusion therapy with implantable reservoir was 50.6% and the 2-year survival rate was 37.8%. The survival rate was 51.4% and 32.2%, respectively, in the TAE cases for the same period. Considering the kinds of reservoirs used for HCC, the survival curve of 23 cases with double lumen reservoir showed a significantly better pattern than that of 24 cases with the usual single lumen reservoir (p less than 0.05). Cumulative usable rate of reservoir was 78.6% at one year, and 42.4% at two years (Kaplan-Meier method). Therapy after the reservoir was unusable, particularly with arterial obstruction by catheter, was restricted because arterial infusion therapy was impossible. It is considered very important to retain the hepatic artery because arterial infusion therapy is mainly for unresectable hepatocellular carcinoma.

Antineoplastic Agents↗
PubMed1992

[A clinical study of liver resections in patients with small hepatocellular carcinoma less than three centimeter in diameter].

Liver resections for 52 cases with small hepatocellular carcinoma (HCC) less than 3cm in diameter were clinically studied. The 5-year-survival rate was 57.1%, which was better than that of percutaneous ethanol injection (PEI) therapy. Histological study revealed infiltration to the capsule in 48.1%, of which 20% had extra-capsular invasion. This finding seemed to be an important problem in PEI therapy. The group in which resected area was much larger than the extent of tumors had a tendency having good cumulative survival and non-recurrence rates. It is thought that the curative resection should be intended for small HCC if the patient has enough hepatic reserve to undertake a curative operation.

Carcinoma, Hepatocellular↗
PubMed1992

[Abnormalities in the signal-averaged electrocardiogram in Ebstein's anomaly].

Abnormalities in the signal-averaged electrocardiogram (SAECG) of patients with Ebstein's anomaly were studied. A SAECG was obtained in 4 patients with Ebstein's anomaly, aged 3 to 25 years. The control groups included 8 patients with atrial septal defect (ASD group), 10 with right bundle branch block (RBBB group), 8 with Wolff-Parkinson-White (WPW) syndrome (WPW group), and 40 normal subjects (Normal group). The SAECG was calculated by the vector-magnitude method using the VCM-3000. The root-mean-square during the initial 20 msec of the filtered QRS (i-RMS) was very small in 2 older patients with Ebstein's anomaly compared to the ASD group, the RBBB group and the Normal group, and was as small as that in the WPW group. This probably was affected by the delta wave associated with Ebstein's anomaly or concealed accessory pathway. The root-mean-square during the terminal 40 msec of the filtered QRS (t-RMS) was small in the patients with Ebstein's anomaly and the RBBB group. Two patients with Ebstein's anomaly had a smaller t-RMS than the RBBB group, suggesting pathological changes of an atrialized right ventricle. In conclusion, SAECG is useful for evaluating patients with Ebstein's anomaly, especially older patients.

Adolescent↗
PubMed1992

[An autopsy case of cerebral embolism caused by atrial myxoma].

We reported an autopsy case of a 14-year-old girl with cardiac myxoma, presenting sudden onset of consciousness disturbance and right hemiplegia while running in an 800 meter race. Though CT scan showed no abnormal findings, cerebral angiogram revealed an embolic stenosis of the left middle cerebral artery, and abdominal aortogram showed complete obstruction of the bilateral common iliac artery. Histological study of emboli taken from obstructed femoral arteries showed systemic embolization of the cardiac myxoma. She died three days after admission. Autopsy was performed. Myxoma tissue was not found, but its stalk was left in the left atrial septum. The brain was very edematous, and a myxoma emboli was found in the left middle cerebral artery. Systemic embolization of myxoma to spleen, kidneys, liver, pancreas, etc. was found histologically. Left atrial myxoma is a rare but potentially treatable cause of stroke, and should be included in the differential diagnosis of cerebral vascular disease, especially in young patients.

Adolescent↗
PubMed1991

Effects of hyperbaric environment on the P300 component of event-related potentials.

Hyperbaric chamber dives at 19 ATA with helium-oxygen were performed at the Japan Marine Science Technology Center, Yokosuka, from January 31 to February 2 in 1990. During simulated underwater experiments, event-related potentials were recorded in 2 divers for assessment of the cognitive function. Although the P300 amplitude of the potentials did not show any significant change, its latency was clearly prolongated and this prolongation continued to when the decompression reached to 70 m below sea level. These findings indicated that the hyperbaric environment corresponding to 180 m below sea level or less must cause some cognitive dysfunctions and that P300 is useful for early detection of those dysfunctions or HPNS.

Cognition↗
PubMed1991

Molecular cloning and structural analysis of mouse gene and pseudogenes for proliferating cell nuclear antigen.

We have isolated clones containing the entire mouse proliferating cell nuclear antigen (PCNA) gene of 3890 bp and flanking sequences using a rat PCNA cDNA as a probe. The mouse gene has 6 exons whose sequences and junction points of exons with introns are extensively homologous to the human gene while sizes and nucleotide sequences of introns are much less conserved than exons. By a transient expression assay of chloramphenicol acetyltransferase, the promoter of this gene is localized within 200 bp upstream of the transcription initiation site. We have also isolated two processed pseudogenes. Homology between the first one (psi PCNA-I) and the exons of the PCNA gene was 76.8% in the region so far sequenced. The second one (psi PCNA-II) consists of a region highly homologous to the entire exons of the PCNA gene, and only 9 out of total 1256 bp are different from the corresponding exon sequence of the gene. The 5'-flanking region of the psi PCNA-II did not function as an active promoter. Surveys in various wild and laboratory mice genomes suggest that the psi PCNA-II was generated through the reverse transcription process of the PCNA mRNA about 5 x 10(5) years ago in the domesticus subspecies of Mus musculus, the house mouse. The psi PCNA-II is tentatively mapped in the chromosome 17 of the C57BL mouse.

Amino Acid Sequence↗
PubMed1991

[Arteriovenous malformation associated with meningioma].

A case of arteriovenous malformation (AVM) associated with a meningioma is reported. A 28-year-old woman was hospitalized for generalized convulsion. CT scan and right carotid angiogram revealed AVM in the right parietal lobe extending to the wall of the lateral ventricle. At the time of surgery an intraventricular meningioma attached to the choroid plexus was found in the excised cavity of the AVM. It is suggested that the meningioma might have been caused by chronic irritation due to an increased blood flow in the arteries supplying the AVM, because the AVM and the meningioma exist in the same lesion and share the same blood supply.

Adult↗
PubMed1991

Formation of Z,E,E-geranylgeranyl diphosphate by rat liver microsomes.

Rat liver microsomes catalyzed the formation of A,E,E-geranylgeranyl diphosphate from farnesyl diphosphate and isopentenyl diphosphate in the presence of Triton X-100. Studies on product specificity using various primers such as Z,E-farnesyl diphosphate, E,E-farnesyl diphosphate, Z,E,E-geranylgeranyl diphosphate, E,E,E-geranylgeranyl diphosphate, Z,E,E,E-geranylfarnesyl diphosphate, and E,E,E,E-geranylfarnesyl diphosphate suggested that the microsomal dehydrodolichyl diphosphate synthase has such properties that it releases Z,E,E-geranylgeranyl diphosphate, the first intermediate, in the reactions with farnesyl diphosphate as the starting primer. Metabolic labeling of rat liver slices with [2-3H]mevalonic acid revealed the accumulation of E,E,E-geranylgeranyl (di)phosphates as well as dolichyl (di)phosphate (C85 and C90) and dehydrodolichol (C85 and C90), but no accumulation of Z,E,E-geranylgeranyl (di)phosphate or E,E-farnesyl (di)phosphate was detected. Microsomal enzyme preparations from mouse liver and hamster liver also produced Z,E,E-geranylgeranyl diphosphate from farnesyl diphosphate and isopentenyl diphosphate.

Alkyl and Aryl Transferases↗