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Biomedical subjects

K Matsuda

Publications and source records attributed to K Matsuda.

931 records · Page 52Linked to original sources
PubMedDate not supplied

Surgical repair for supravalvular aortic stenosis: intermediate to long-term follow-up.

BACKGROUND AND AIM OF THE STUDY: Supravalvular aortic stenosis (SAS) has been surgically treated by either single-sinus or bisinus patch repair. This article reviews intermediate to long-term results of repair in patients with SAS at our institute. METHODS: Between 1974 and 1995, eight patients underwent surgical repair for SAS. The age range was 1.3 to 14 years (mean 7.3 years). The morphology was the discrete type in seven patients and the diffuse type in one patient. The pressure gradient across the obstruction was 20 to 105 mmHg (mean 68 mmHg). Two patients in the early period of the series underwent single-sinus patch repair, and six underwent bisinus patch repair (pantaloon-shaped patch, extended aortoplasty). RESULTS: There were no operative deaths, and the mean pressure gradient was reduced to 23 mmHg (p < 0.001) in the early postoperative period. The median follow-up period was 8.0 years (1.8-17.3 years). One patient with diffuse type SAS required reoperation 12.8 years later due to progression of the stenosis, and died after the operation. The remaining seven patients were alive and well at the last follow-up, when the pressure gradient ranged from 6 to 31 mmHg (reoperation excluded). CONCLUSION: Surgical repair for discrete type SAS provides satisfactory results in the intermediate to long-term follow-up.

Adolescent↗
PubMedDate not supplied

Development of monovalent ions in the endolymph in mouse cochlea.

The present study was designed to clarify the chronological developmental process of monovalent ions (Na(+), K(+), Cl(-)) in the endolymph of the mouse in relation to the development of the endocochlear potential (EP). The EP and ionic concentrations were measured simultaneously with the ion-sensitive double-barreled microelectrodes from the scala media of the basal turn. The EP increased abruptly 7 days after birth (DAB) and reached approximately 80 mV 14 DAB. In the earliest postnatal days, the endolymphatic Na(+) concentration was significantly higher than that in adult mice, however, the K(+) and the Cl(-) concentrations were lower. The concentrations of all the monovalent ions in endolymph reached adult levels at 7 DAB when the EP was still under 20 mV. These data strongly suggest the presence of a different mechanism between the production of monovalent ions, especially of high K(+) in the endolymph and that of EP.

Animals↗
PubMedDate not supplied

Different clinical characteristics of aminoglycoside-induced profound deafness with and without the 1555 A-->G mitochondrial mutation.

Recent genetic studies have shown that hereditary susceptibility to aminoglycoside antibiotics is caused by the 1555 A-->G mitochondrial mutation. We found the 1555 mutation in 4 out of 68 postlingual deaf patients who were candidates for cochlear implantation. All 4 patients developed bilateral profound hearing loss following administration of aminoglycosides. The pedigree of the family shows exclusively maternal transmission of hearing impairment in each case. On comparison with neuro-otological findings from aminoglycoside-induced deaf patients without the 1555 mutation, four distinct characteristics were noted: (1) a progressive nature of hearing loss; (2) better residual pure-tone thresholds; (3) lower thresholds for electrical promontory stimulation, and (4) well-preserved vestibular function. Although other factors such as differing dosages and/or administration routes may also be involved, profound hearing loss associated with the 1555 mutation may be due to a different pathogenic mechanism, i.e., strial dysfunction rather than a direct insult to the hair cells.

Aged↗
PubMedDate not supplied

Influences of endothelium on the time course of noradrenaline-, 5-HT-, prostaglandin F2alpha- and high-K+-induced contractions in aortae of WKY and SHRSP.

Influences of endothelium on contraction of aortic smooth muscle by various agents were studied and those in the preparations from Wistar Kyoto rat (WKY) and stroke-prone spontaneously hypertensive rats (SHRSP) were compared. Endothelium depressed the contractions induced by noradrenaline and 5-hydroxytryptamine (5-HT). The time course of the contraction was bi- or tri-phasic in the former and slow rising monophasic in the latter. On the other hand, the depression was weaker in the contraction by prostaglandin F2alpha- and high K+. The depression was blocked by the removal of endothelium or in the presence of Nomega-nitro-L-arginine (L-NNA), indicating that nitric oxide (NO) released from endothelium was responsible for the inhibition. The inhibition was weaker in the preparation from SHRSP when compared to that in the preparation from WKY. Relaxation by acetylcholine (ACh) of the preparation precontracted in the presence of respective contractile agent was impaired in the preparation from SHRSP. It is concluded that mode of inhibition of the contraction varies depending on the agents used to initiate the contraction, i.e. depending on the mode of the release of NO. In the preparation from SHRSP, the influence of endothelium is impaired due to the reduced release of NO.

Acetylcholine↗
PubMedDate not supplied

Involvement of endothelium-derived factors in controlling the active tone of smooth muscle in aorta from hypertensive rats.

Control of the active tone by endothelium in aortae from various strains of spontaneously hypertensive rats was studied. The active tone was negligibly observed in endothelium-intact preparation. The application of N(G)-nitro-L-arginine (L-NNA, 10(-4) M) induced slowly developed active tone in the preparations from hypertensive rats but no active tone was induced in the preparation from normotensive Wistar Kyoto rats (WKY). The developed tension was stronger in preparations from rats with higher blood pressure as observed in endothelium denuded preparations. The developed active tone in the presence of L-NNA was greater than that observed in endothelium denuded preparations. The active tone was abolished by the removal of extracellular Ca2+ or by the application of Ca-antagonists. L-arginine counteracted the effects of L-NNA and depressed the developed active tone in the presence of the latter drug. The application of indomethacin (10(-5) M) depressed the active tone of the preparations from SHRSP by 25.5+/-5.2%. Increasing extracellular K+ concentration or application of tetraethylammonium (TEA) could not be used to observe the effect of endothelium-derived factors on the active tone, because of their strong contractile effect. Simultaneous application of apamin and charybdotoxin induced an elevation of tension which was often associated with spontaneous tension oscillation. It is concluded that the active tone, which is smooth muscle origin, is depressed by endothelium-derived nitric oxide (NO) strongly and potentiated by a product of arachidonic acid cascade through cyclooxygenase pathway. The involvement of endothelium-derived hyperpolarizing factor (EDHF) in the depressing effect of endothelium is thought to be small.

Animals↗
PubMedDate not supplied

Clinical evaluation of hepatic arterial infusion of low dose-CDDP and 5-FU with hyperthermotherapy: a preliminary study for liver metastases from esophageal and gastric cancer.

BACKGROUND/AIMS: The prognosis for gastric and esophageal cancer patients with liver metastases remains very poor. In most cases, liver metastasis is unresectable because of its number, size and location and therefore, other approaches need to be considered. METHODOLOGY: In this study we examined 4 patients. We showed the therapeutic benefits of employing hepatic arterial infusion of low-dose CDDP and 5-FU combined with hyperthermia for the treatment of liver metastases of gastric and esophageal cancer. RESULTS: All patients showed partial response, and bone marrow toxicities and gastrointestinal toxicities were extremely slight while liver toxicities were not observed at all. Moreover, 3 of the patients excluding patient 3 who had metastatic lesions other than liver metastases have still been alive for more than 17 months (17-28 months) maintaining a good quality of life. CONCLUSIONS: Therefore, it is suggested that the merits of both low dose-FP and hepatic arterial infusion chemotherapy contribute to ideal clinical effects, and that hyperthermotherapy could enhance clinical responses without potentiating any toxicities. However, this is just a preliminary study, and therefore, a prospective randomized control study is necessary to evaluate the efficiency of this therapy.

Aged↗
PubMedDate not supplied

In vitro antitumor effect of topoisomerase-I inhibitor, CPT-11, on freshly isolated human gastric and colorectal cancer.

CPT-11 is a comptothecin analogue which has shown a broad spectrum of strong antitumor effect against various cancers, including gastroenterological malignancies. In the present study, the antitumor effect of CPT-11 was determined by MTT assay for freshly isolated human gastric and colorectal cancer cells, especially highly purified tumor cells. Twenty-three patients with gastric cancer, and 32 patients with colorectal cancer were enrolled in this study. Three gastric and 3 colonic cancer cell lines were used to study the antitumor effect of CPT-11, and freshly isolated cancer cells from 3 patients with gastric cancer were investigated. The in vitro antitumor effect was tested by MTT assay, and showed % inhibition rate. CPT-11 and SN-38 showed the antitumor effect as a dose dependent matter for human gastric and colorectal tumor cells in vitro. From the results of chemosensitivity for freshly isolated gastric and colorectal tumor cells, antitumor effect of SN-38 was as strong as other conventional anticancer agents. It was demonstrated that the MTT assay was appropriate for the analysis of the antitumor effects of CPT-11 and SN-38, and that CPT-11 may be a worthwhile choice as an anticancer agent against gastric and colorectal cancer.

Antineoplastic Agents↗
PubMedDate not supplied

Primary intestinal obstruction complicated by persistent descending mesocolon.

Persistent descending mesocolon is an uncommon developmental anomaly which results from failure of fusion of the descending mesocolon with the posterior parietal peritoneum. It is asymptomatic in most cases and rarely causes intestinal obstruction. We report here a case of primary intestinal obstruction complicated by a persistent descending mesocolon. A 66-year-old man without prior laparotomy was admitted with a diagnosis of small bowel obstruction. Pre-operative investigation demonstrated a segmental jejunal stenosis and a persistent descending mesocolon as possible causes of the obstruction. Laparotomy showed that the cause of the obstruction was the jejunal stenosis, not the persistent descending mesocolon. The stenosis was resected, but correction of the anomaly was not performed. The patient made an uneventful recovery after the operation. From our limited experience, persistent descending mesocolon need not be surgically corrected when it is not considered to be the cause of obstruction and another definite cause co-exists.

Aged↗
PubMedDate not supplied

A magnetically suspended centrifugal pump. In vitro and in vivo assessment.

To overcome problems derived from the shaft within conventional centrifugal pumps, we have developed a new centrifugal pump, the magnetically suspended centrifugal pump (MSCP), which has no shaft and operates as a bearingless centrifugal pump. The impeller is suspended freely and centrally by magnetic force within the pump. Hemolysis tests were performed in comparison with the Biopump. Index of hemolysis and destruction of platelets were significantly lower in the MSCP than in the Biopump. Animal studies were designed to evaluate the durability and antithrombogenicity of the MSCP. Short-term animal studies were performed using two mongrel dogs. Left heart bypass was established with the MSCP. After 3 hr, the layer of thrombus adherent to the surface of the polycarbonate impeller impaired pumping efficiency. However, using the impeller coated with silicone, no thrombus was observed on the impeller after continuous pumping for 24 hr. In addition, long-term animal studies were performed using two sheep. Left heart bypass was established with the MSCP containing an impeller coated with silicone. In one sheep, the MSCP ran for 14 days without problems in pumping performance and showed no thrombus within the pump. In the other sheep, the MSCP ran for 15 days, and showed no thrombus on the impeller. During each experiment, plasma free hemoglobin levels were less than 15 mg/dl. The MSCP induced less hemolysis than did the Biopump, and the MSCP containing an impeller coated with silicone demonstrated the potential to run for 14 days without thrombus formation within the pump.

Animals↗
PubMedDate not supplied

Response of unresectable pancreatic cancer to intraoperative radiotherapy.

Eight patients with unresectable pancreatic cancer were treated by intraoperative radiotherapy (IORT) with electron beams, and the tumor responses were followed using serial CT scans. In five cases, external beam irradiation with 10 MV X-rays was added. While there was no evident change after 2-3 weeks, 6-8 weeks after IORT partial responses were noted in all five examined cases. Furthermore, 12-16 weeks after IORT, three out of five examined patients showed good tumor response with more than 75% regression. Mean survival time was 8.0 +/- 2.7 months. Two patients who lived longer than 1.5 years had shown excellent tumor responses. Serial CT scans in the early period following IORT allowed accurate estimation of the tumor response, which might predict some long-surviving cases.

Aged↗