Search PubMed⌕ Search

Biomedical subjects

Y Moriyama

Publications and source records attributed to Y Moriyama.

At least 91 records · Page 5Linked to original sources
PubMed1999

Repair of an acute type A dissection: fate of the remnant false lumen and preserved aortic valve.

From January 1992 through March 1997, 75 patients (DeBakey type I/II = 56/19) underwent a surgical repair of a type A acute dissection. The patients included 37 men and 38 women ranging in age from 23 to 83 years with a mean of 65 years. All patients were admitted to our hospital with a mean interval of 2.2 days from the episode of onset. The overall hospital mortality rate was 25% (19/75). There were three late deaths among the 56 patients discharged from the hospital. The actuarial survival rate for the patients surviving the operation was 87% at 5 years after repair. A subsequent aortic operation was necessary in 6 patients, while 3 other patients who had late aortic complications were put on medical therapy alone. As a result, the aortic event-free survival rate was 54% at 5 years. For a type I dissection the false lumen was completely thrombosed after repair in 34%. The descending thoracic aorta with a patent false lumen was markedly enlarged in proportion to the follow-up time. After a conservative approach to the aortic valve, all but one patient demonstrated an adequate valve function throughout this study period. This experience with a midterm follow-up showed an acceptable durability of the preserved aortic valve and a progressive enlargement of the persistent false lumen with a high rate of aortic complications. Hence, all patients with a type A dissection need a close follow-up to assess the aorta for complications of either recurrent or residual aneurysms and dissections.

Acute Disease↗
PubMed1999

Myxoma of mitral valve associated with infective endocarditis.

A 20-year-old man was hospitalized for persistent fever, embolism, and syncopal attack. Echocardiography demonstrated a tumor on the mitral posterior leaflet. It was removed under extracorporeal circulation following extirpation of thrombus in the right common like artery. The tumor consisted of myxoma and vegetation with bacterial colony. Myxoma and/or vegetation had destroyed the mitral posterior leaflet. Accordingly, it was necessary to perform mitral valve replacement. The postoperative course was uneventful. This is the 14th surgical case of mitral valve myxoma, and the first case of that associated with infective endocarditis.

Adult↗
PubMed1999

Coronary artery aneurysm after stent implantation.

A coronary artery aneurysm that developed 6 months after coronary stent implantation in the left anterior descending artery, was treated by double coronary artery bypass grafting due to restenosis of the affected vessel and progression of right coronary artery stenosis. Although the poststenting aneurysm initially remained postoperative angiography showed that it had disappeared. In addition to thrombotic occlusion, another mechanism behind its disappearance may be that geometric changes of the implanted stent caused by heart retraction during surgery closed the entrance to the aneurysm.

Adult↗
PubMed1999

Is direct closure dangerous for treatment of doubly committed subarterial ventricular septal defect?

BACKGROUND: We performed direct closure of doubly committed subarterial ventricular septal defects with aortic cusp prolapse. Postoperative echocardiographic studies showed that this method improved coaptation of the prolapsing aortic cusp, especially in patients with mild aortic regurgitation (AR). METHODS: Twenty-one patients (mean age, 7.8+/-4.3 years; range, 2 to 18 years) with doubly committed subarterial ventricular septal defect underwent direct closure alone. Aortic valve prolapse was observed in all 21 patients, with mild AR found in 13 patients but not in the remaining 8. The site of the prolapsed aortic valve was in the right coronary cusp in all patients. We inserted an interrupted 4-0 or 5-0 polypropylene suture with a pledget from the lower margin of the ventricular septal defect to the pulmonary ring to increase protrusion of the prolapsed cusp by pushing it back and to improve coaptation of the aortic cusp. RESULTS: The interval between surgical treatment and the last postoperative evaluation ranged from 3 to 24 months (median, 11 months). No residual ventricular septal defect was detected in any patient. In the 8 patients who had aortic valve prolapse without AR preoperatively, no AR was found at follow-up. Of the 13 patients who had mild AR associated with aortic valve prolapse preoperatively, AR diminished in 7 and did not progress in the remaining 6. Furthermore, no anatomic changes in either the aortic or pulmonary annulus were found on follow-up echocardiography. In the group of 13 patients with mild preoperative AR, AR significantly persisted in patients who were more than 10 years old at operation (p<0.05). CONCLUSIONS: Our findings suggest that direct closure for this type of ventricular septal defect is safe and reliable in improving mild AR and that direct closure is more effective for younger patients in whom the prolapsing aortic cusp is mobile enough to be protruded. However, further long-term follow-up studies will be needed to ascertain the adequacy and usefulness of the method.

Adolescent↗
PubMed1999

Rubber-like elasticity and volume changes in the isolated spasmoneme of giant Zoothamnium sp. under Ca2+-induced contraction.

Using glycerinated spasmoneme of giant Zoothamnium sp., the physical properties of spasmoneme before and after Ca2+-induced contraction (pCa 4.5) were investigated. The volume change of spasmoneme contraction was measured under zero tension. The length and diameter decreased by about 50% of their initial value as a result of contraction, which means that contraction is nearly isotropic. Thus the volume of spasmoneme decreased drastically by 86% of its original value. The swollen ratio of extended and contracted spasmoneme were 0.07 and 0.37, respectively. Tension-extension relationships of extended and contracted spasmonemes were measured. By applying the theory of rubber elasticity, the number of segments of a chain in originally extended spasmoneme was only 3.3, i.e., the chain was almost a straight one. On the other hand, the number of segments of a chain in contracted spasmoneme was more than 100, i.e., the chain was essentially a random one. Furthermore, the total number of chains in single spasmoneme was the same in extended and contracted spasmoneme. This means that the interchain cross-links of chains were not influenced by addition or removal of Ca2+. Moreover, the molecular weight of a chain is estimated to be at most about 50 kd. By considering all these results, it is concluded that the contractile mechanism of spasmoneme originates in the intramolecular folding and unfolding induced by Ca2+ binding and detaching.

Animals↗
PubMed1999

Improvement of endothelial vasomotor dysfunction by treatment with alpha-tocopherol in patients with high remnant lipoproteins levels.

OBJECTIVES: This study sought to examine whether oral intake of alpha-tocopherol, an antioxidant, could improve endothelium-dependent vasorelaxation in patients with high remnant lipoproteins levels. BACKGROUND: Remnant lipoproteins are known to be atherogenic and impair endothelium-dependent arterial relaxation, but the underlying mechanisms remain unclear. Oxidative stress is a common feature of various risk factors for atherosclerosis. METHODS: Flow-mediated vasodilation of the brachial artery during reactive hyperemia was examined by high resolution ultrasound technique before and at the end of 4 weeks treatment with oral administration of alpha-tocopherol acetate (300 IU/day) or placebo, which was randomly assigned, in 40 patients with high serum levels of remnants and in 30 patients with low remnants levels in the fasting state (>75th percentile and <25th percentile, respectively, of the distribution of remnants levels in 150 consecutive hospitalized patients). RESULTS: Before treatment, flow-mediated vasodilation was lower in patients with high remnants levels than in those with low levels (4.1 +/- 0.3% vs. 6.0 +/- 0.5%, p < 0.01). Treatment with alpha-tocopherol but not with placebo significantly increased flow-mediated dilation in patients with high remnants levels (7.5 +/- 0.4% after alpha-tocopherol vs. 4.2 +/- 0.4% after placebo, p < 0.01). In patients with low remnants levels, alpha-tocopherol was not effective. The beneficial effect with alpha-tocopherol in high remnants patients was associated with decrease in plasma levels of thiobarbituric acid reactive substances, an indicator of lipid peroxidation (6.6 +/- 0.3 nmol/ml before alpha-tocopherol vs. 4.6 +/- 0.3 after alpha-tocopherol, p < 0.05). CONCLUSIONS: Alpha-tocopherol improved impairment of endothelium-dependent vasodilation in patients with high remnants levels. The increase in oxidative stress may at least partly contribute to endothelial vasomotor dysfunction, in patients with high remnants levels.

Adult↗
PubMed1999

Inactivation of both alleles of the DPC4/SMAD4 gene in advanced colorectal cancers: identification of seven novel somatic mutations in tumors from Japanese patients.

Loss of heterozygosity (LOH) of loci on chromosome 18q occurs in a majority of colorectal cancers. The DPC4/SMAD4 gene, lying in close proximity to the DCC gene at 18q21.1, was recently identified as a candidate tumor suppressor for the genesis of pancreatic cancer as well as a predisposing gene for Juvenile Polyposis Syndrome (JPS). The gene product functions as a cytoplasmic mediator in the signaling pathway of transforming growth factor beta (TGF-beta). To investigate the potential role of DPC4/SMAD4 gene in colorectal cancers, we examined 73 tumors of clinical stages II or III from Japanese patients, for LOH at 18q21 and also for subtle mutations anywhere within the coding region of DPC4/SMAD4. LOH was identified in 50 (78%) of the 64 tumors that were informative for polymorphic markers in the region. Somatic mutations were identified in seven of those tumors: two frameshift mutations, a 1-bp deletion (326 del T) in exon 8 and a 1-bp insertion (50-51 ins A) in exon 1; two nonsense mutations, Arg445Ter in exon 10 and Glu538Ter in exon 11; and three missense mutations, Asn129Lys in exon 2, Tyr95Asn in exon 2, and Asp355Glu in exon 8. Three of the seven mutations were observed in the mad homology 1 (MH1) domain encoded by exons 1 and 2. In all of the tumors carrying intragenic mutations of one allele, LOH analysis had shown that the other allele was missing. The results demonstrated that inactivation of both alleles of the DPC4/SMAD4 gene occurs in a substantial proportion of advanced colorectal cancers, and that the DPC4/SMAD4 gene probably exerts a tumor-suppressor effect for colorectal carcinogenesis that fulfills the criterion of the two-hit concept proposed by Knudson [A.G. Knudson, Hereditary cancer, oncogenes, and anti-oncogenes, Cancer Res. 45 (1985) 1437-1443.].

Alleles↗
PubMed1999

Vesicular monoamine transporter 1 is responsible for storage of 5-hydroxytryptamine in rat pinealocytes.

Vesicular monoamine transporters (VMATs) are involved in chemical transduction in monoaminergic neurons and various endocrine cells through the storage of monoamines in secretory vesicles. Mammalian pinealocytes contain more 5-hydroxytryptamine (5-HT) than any other cells and are expected to contain VMAT, although no information is available so far. Upon the addition of ATP, radiolabeled 5-HT was taken up by a particulate fraction prepared from cultured rat pinealocytes. The 5-HT uptake was inhibited significantly by bafilomycin A1 (an inhibitor of vacuolar H+-ATPase), 3,5-di-tert-butyl-4-hydroxybenzylidenemalononitrile (a proton conductor), or reserpine (an inhibitor of VMAT). RT-PCR analysis suggested that VMAT type 1 (VMAT1), but not type 2, is expressed. Antibodies against VMAT1 recognized a single polypeptide with an apparent molecular mass of approximately 55 kDa, and specifically immunostained pinealocytes. VMAT1 immunoreactivity was high in the vesicular structures in the varicosities of long branching processes and was associated with 5-HT, but not with synaptophysin, a marker protein for microvesicles. The 5-HT immunoreactivity in the long branching processes disappeared upon incubation with reserpine. These results indicate that 5-HT, at least in part, is stored in vesicles other than microvesicles in pinealocytes through a mechanism similar to that of various secretory vesicles.

Adenosine Triphosphate↗
PubMed1999

Effectiveness of preoperatively obtained autologous platelet concentrates in open heart surgery.

BACKGROUND: Autologous blood components have been widely introduced in open heart surgery. However, the effectiveness of autologous platelet products remains controversial. METHODS: Autologous platelet concentrates (PC) were collected from patients (n = 35) scheduled for primary valvular heart surgery 1 to 3 days before the operation and were transfused immediately after cardiopulmonary bypass. Blood loss and platelet-related factors were compared with the control patients who had no PC (n=35). RESULTS: There were no serious complications in harvesting, preservation, and transfusion of autologous PC. The maximal platelet aggregation response significantly improved after its transfusion and tended to be higher with autologous PC stored 1 day than with ones stored 2-3 days. Activation of coagulation and fibrinolytic factors did not significantly differ between the groups. Postoperative blood loss was significantly less in autologous PC group, and seemed to have a negative correlation with platelet aggregation response. CONCLUSIONS: Autologous PC can be safely prepared and are clinically effective in reduction of postoperative blood loss in open heart surgery.

Aged↗
PubMed1999

Effects of sarpogrelate hydrochloride on platelet aggregation, and its relation to the release of serotonin and P-selectin.

Inhibitory effects of sarpogrelate hydrochloride (sarpogrelate), a 5-HT2 receptor antagonist, on platelet aggregation was examined as well as the relationship to serotonin and P-selectin, a platelet alpha-granule membrane glycoprotein. Platelet aggregation was induced by simultaneous addition of collagen (0.06-0.12 microg/ml), which did not induce aggregation alone, and serotonin (0.88 micromol/1) to platelet-rich plasma (PRP). The PRP was obtained from healthy volunteers and percentage maximum aggregation (MA) was measured. Serotonin levels and P-selectin levels in the supernatant of PRP after aggregation were determined. When vehicle-treated PRP was stimulated in the aforementioned manner, platelet aggregation dependent on collagen concentration was induced. Serotonin levels and P-selectin levels were also dependent on collagen concentration. Sarpogrelate (10(-6) to 10(-4) mol/l) inhibited such aggregation dose-dependently, and decreased serotonin levels and P-selectin levels in a dose-dependent manner. There were close correlations between MA and serotonin levels, MA and P-selectin levels, as well as serotonin and P-selectin levels. These results suggest that extracellular release of serotonin and P-selectin from platelets was caused by induction of aggregation, and these responses were suppressed by sarpogrelate.

Adult↗
PubMed1999

Localization of a target region of allelic loss to a 1-cM interval on chromosome 16p.13.13 in hepatocellular carcinoma.

To identify the location of the putative tumor suppressor gene on chromosome 16p that may be involved in hepatocellular carcinoma (HCC), we examined 96 primary HCCs and evaluated their patterns of allelic loss at 10 microsatellite marker loci distributed along this chromosome arm. Allelic loss at one or more loci was observed in 46 (48%) of these tumors. Through detailed deletion mapping of tumors having partial or interstitial deletions, we identified a commonly deleted region at a 1-cM interval, flanked by D16S519 and D16S3078 at 16p13.13, defining the location of a putative tumor suppressor gene for HCC. This region contains the gene for JAB (JAK-binding protein), which is responsible for negative-feedback regulation of the JAK-STAT pathway induced by cytokine stimulation, raising the possibility that inactivation of this gene may participate in hepatocarcinogenesis via genetic and/or epigenetic changes.

Carcinoma, Hepatocellular↗
PubMed1999

Experimental His-bundle pacing: histopathological and electrophysiological examination.

His-bundle pacing gives a more physiological ventricular contraction in comparison to right ventricular apical pacing. However the problems of lead fixation and stability of long-term His-bundle pacing are yet unsolved. We used six adult beagles, in which a screw-in lead was anchored in the His-bundle region for observation of the pacing conditions and histopathologic changes of the conduction system over the course of 2 months. In the results, a satisfactory fixation was obtained using a conventional screw-in lead and no histological influence on the conduction system was observed. The pacing threshold at the time of implantation was 1.15 +/- 0.69 V (3.23 +/- 3.08 mA) in the pulse width of 0.5 ms. R wave amplitude, the impedance and slew rate were 7.28 +/- 2.04 mV, 409 +/- 102 Ohm, and 0.65 +/- 0.41 V/s, respectively. Two months later, these parameters changed to 2.83 +/- 1.06 V (10.4 +/- 5.71 mA), 5.63 +/- 1.62 mV, 310 +/- 71.3 Ohm, and 0.49 +/- 0.22 V/s, respectively. These results suggest the feasibility of clinical application of permanent His-bundle pacing.

Animals↗
PubMed1999

Ultrasonic evaluation of congestive liver after tricuspid annuloplasty.

To assess the effect of tricuspid annuloplasty (TAP), the authors measured the size of the liver by using echography in the patients undergoing tricuspid annuloplasty. From April 1989 to August 1996, 18 patients underwent TAP. The authors measured preoperatively and postoperatively the hepatic index (HI) by echography, defined as follows: HI=L x D/BSA (L: the top-to-bottom length of the left hepatic lobe; D: the front-to-back length of the left hepatic lobe; BSA: body surface area). They also calculated the reducing rate (RR) of HI. The mean HI decreased after TAP; preoperative HI: 39.7+/-11.8 vs postoperative HI: 33.8+/-10.5 (p=0.0069). The RR of the patients with postoperatively residual tricuspid regurgitation (TR) over 2 degrees (n=4) was significantly lower than that of the other patients (n=14): -11.0+/-6.0% vs 20.2+/-3.2% (p=0.0003). They conclude that the use of echography to measure the HI is a good method of assessing congestion after TAP.

Female↗