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O Sato

Publications and source records attributed to O Sato.

At least 55 records · Page 3Linked to original sources
PubMed1999

Targeting endogenous platelet-derived growth factor B-chain by adenovirus-mediated gene transfer potently inhibits in vivo smooth muscle proliferation after arterial injury.

Platelet-derived growth factor (PDGF), especially its B chain, has been implicated in the pathogenesis of vascular proliferative disorders such as atherosclerosis and restenosis after angioplasty. We constructed a replication-deficient recombinant adenovirus containing the gene encoding the extracellular region of PDGF beta-receptor (PDGFXR) that binds PDGF-B chain and acts as its antagonist. The administration into balloon-injured rat carotid arteries of an adenovirus containing the Escherichia coli lacZ gene as a marker gene at 5 days after injury markedly facilitated efficacy of gene transfer, as compared with its administration immediately after injury. Adenovirus-mediated gene transfer of PDGFXR into injured arteries performed at 5 days resulted in a more than 50% reduction in the neointimal area of injured arteries at 14 days. In contrast, the administration of control adenoviruses containing lacZ gene or containing no foreign gene was without suppressive effects on neointima formation. The inhibition of neointima formation by the expression of PDGFXR was accompanied by a reduction in bromodeoxyuridine-labeled cells and nearly complete inhibition of tyrosine phosphorylation of both alpha- and beta-receptors for PDGF, but not of epidermal growth factor receptor, in injured arteries. This is the first report to indicate the usefulness of targeting a growth factor by expressing an extracellular binding region of a receptor using an adenovirus for the treatment of vascular proliferative disorders, and provide direct evidence that PDGF-B chain plays an essential role in neointimal formation.

Adenoviridae↗
PubMed1999

Effect of vanadate on force and myosin light chain phosphorylation in skinned aortic smooth muscle.

The effects of vanadate were examined on Ca2+-activated force and phosphorylation of 20-kDa myosin light chain in membrane-permeabilized rabbit aortic smooth muscle strips. Addition of vanadate during maximum contraction reduced the force in a dose-dependent manner, and inhibited it almost completely at 1 mM. Two-dimensional polyacrylamide gel electrophoretic analyses revealed that vanadate also reduced the phosphorylation of 20- kDa myosin light chain in a dose-dependent manner from approximately 50% in the absence of vanadate to approximately 20% in the presence of 1 mM vanadate. The effects of 1 mM vanadate on purified myosin light chain kinase and phosphatase were then examined using purified myosin as substrate, and it was found that vanadate neither inhibited myosin light chain kinase nor activated myosin light chain phosphatase. These results indicate that the reduction in the 20-kDa myosin light chain phosphorylation level by vanadate may be effected through its inhibition of the force generation in skinned smooth muscle strip, as evidenced by the finding that vanadate eliminated the enhancement of myosin light chain kinase activity brought about by the interaction between purified myosin and actin.

Actins↗
PubMed1999

The modulatory effect of MgATP on heterotrimeric smooth muscle myosin phosphatase activity.

Regulation of the enzymatic activity of heterotrimeric smooth muscle myosin phosphatase (SMMP) by MgATP was examined using phosphorylated myosin (P-myosin), heavy meromyosin (P-HMM), subfragment-1 (P-S1), and 20 kDa myosin light chain (P-MLC(20)) as substrates. The activity toward P-myosin and P-HMM was dose-dependently reduced by MgATP, whereas that toward P-S1 or P-MLC(20) was unchanged. The reduction was mainly due to a decrease in the affinity of SMMP for the substrate with the unchanged maximum activity. This regulation is entirely new in the respect that the responsible molecule is the substrate, not SMMP. Because P-myosin derived from myosin stored in 50% glycerol at -20 degrees C was insensitive to MgATP, the proper integrity of P-myosin is required. Coexisting myosin did not affect this regulation, but it inhibited the SMMP activity in the absence of MgATP. With P-myosin, the enzyme activity was biphasically steeply dependent on the ionic strength. This requires that determinations are conducted with a fixed ionic strength. The Q(10) value was about 2, which was quite similar to that for myosin light chain kinase. These results suggest that the rate of dephosphorylation of P-myosin is lowered at rest, but that it may reach a value comparable to the rate of phosphorylation of myosin in the sarcoplasm with the increased level of P-myosin during muscle activation. This regulation by MgATP may underlie the "latch mechanism" in some respects.

Adenosine Triphosphate↗
PubMed1999

Nondissection method in distal arterial bypass surgery.

One of the most conspicuous advances in vascular surgery during the past two decades has been the improvement of the patency of distal bypasses. The nondissection method, in particular, has made a great contribution to better the tibioperoneal bypass patency. This review describes the operative procedure and background of the method, in which only the vascular sheath of the recipient artery is exposed and circumferential dissection of the artery avoided. The limb is exsanguinated with an Esmarch's bandage, and haemostasis is maintained with a pneumatic tourniquet. Vascular clamps are not applied to the artery at the distal anastomotic site. In a series of 42 tibial bypasses, a primary revised patency of 84% has been achieved after five years with this method.

Anastomosis, Surgical↗
PubMed1998

Modulatory effect of MgATP on smooth muscle myosin phosphatase activity.

To deepen our understanding of the regulatory mechanism of smooth muscle contraction, we examined properties of smooth muscle myosin phosphatase (SMMP) which was purified from chicken gizzard according to the method of Alessi et al. with slight modifications. The SMMP was a heterotrimer of 130, 37 and 20 kDa subunits as reported. Because the enzymatic activity was strongly dependent on the ionic strength, all experiments were carried out at a constant ionic strength of 0.15 M. The Vmax and K(m) of the enzyme toward bovine stomach phosphorylated myosin was 25.2 mumol/mg protein/min and 0.45 microM at 25 degrees C, respectively, which implied that the rate of dephosphorylation by SMMP in smooth muscle cells should be comparable to that of phosphorylation by the myosin light chain kinase in the presence of a saturating Ca2+ concentration. ATP dose-dependently decreased the SMMP activity to one-fifth. The IC50 for ATP was 0.6 microM in the presence of 5 mM MgCl2, whereas it increased to 10 microM in the absence of Mg2+ with the addition of 1 mM EDTA. ADP, AMP, GTP and ITP showed no or only weak effect. The finding that ATP gamma S was ineffective indicates that phosphorylation of the 130 kDa subunit cannot be the underlying mechanism. This modulation was observed with myosin from bovine stomach, but not from chicken gizzard. The difference in conformation of myosin molecules in the presence of MgATP may be critical in its modulatory effect.

Adenosine Triphosphate↗
PubMed1998

Aortoesophageal fistula: report of an unusual case.

We report herein the case of a patient with an aortoesophageal fistula (AEF) who was managed successfully by surgery. A 5-mm oval, well circumscribed aortic perforation just above the orifice of the celiac axis and a 4-mm defect in the esophagus were primarily closed, and an omental flap was placed between the aorta and the esophagus. No definite etiology could be determined. Our experience of this case suggests that primary closure for defects in both the aorta and the esophagus is the best option when the defects are small, and that the possibility of an AEF must be considered in patients with midthoracic pain or hematemesis, even if there is no history of thoracic aortic aneurysm, foreign body ingestion, trauma, or esophageal disease.

Adult↗
PubMed1998

Utilization of the lateral circumflex femoral artery as a midway outflow for aorto-popliteal grafting: report of a case.

We describe herein the case of a patient who presented with total occlusion of all the major arteries in the unilateral iliofemoral region, including the distal deep femoral artery, on whom an aortolateral circumflex femoral-popliteal artery sequential bypass was successfully performed. This case report serves to demonstrate that the lateral circumflex femoral artery can provide a suitable midway outflow for aortopopliteal bypass in patients with extensive thrombosis of the iliofemoral arteries.

Aged↗
PubMed1998

Value of thallium-201 scintigraphy in bone and soft tissue tumors.

The potential role of thallium-201 (201Tl) scintigraphy in the imaging of various musculoskeletal tumors was investigated in 80 patients. Uptake of 201Tl was observed in 17 (100%) malignant bone tumors, 6 (100%) giant cell tumors, and 2 of 8 (25%) benign bone tumors. Nineteen of 30 malignant soft tissue tumors (63%) were positive for 201Tl scintigraphy, while 2 of 14 benign soft tissue tumors (14%) yielded positive results. None of 6 liposarcomas were visualized by 201Tl scintigraphy. There was no 201Tl uptake in the tissues of 5 non-tumorous conditions. Ten patients with osteosarcoma were evaluated by 201Tl scintigraphy both pre- and post-chemotherapy. There was a significant correlation between changes in tumor-to-normal count ratio and percent necrosis of the resected tumor. The mean decrease in tumor-to-normal count ratio was 71% for patients with >/=90% tumor necrosis and 26% for those with <90% tumor necrosis. Serial 201Tl scintigraphy, with quantitative analysis of alterations in 201Tl uptake, may provide a quantitative and objective measure of the effect of preoperative chemotherapy in patients with malignant bone tumors.

Adolescent↗
PubMed1998

Anastomotic aneurysms after surgical treatment of Takayasu's arteritis: a 40-year experience.

PURPOSE: To evaluate the clinical characteristics of anastomotic aneurysms that develop in surgically treated patients with Takayasu's arteritis. METHODS: Among 103 patients with Takayasu's arteritis treated surgically over 40 years, 91 patients with 259 anastomoses (allowing for exclusion of 12 operative deaths) participated in follow-up study from 1 month to 37.3 years with a mean value +/- SEM of 17.3 +/- 1.1 years with a follow-up completion rate of 93% at 30 years. The clinical characteristics of anastomotic aneurysms were clarified, and the influences of several factors (sites of anastomoses, occlusive or aneurysmal disease, suture material, preoperative systemic inflammation, and administration of corticosteroids) on formation of anastomotic aneurysms were analyzed by means of life-table method and Cox regression analysis. RESULTS: Twenty-two uninfected anastomotic aneurysms were found among 14 patients (22 of 259 anastomoses, 8.5%). The interval between the previous operation and diagnosis varied from 1.6 to 30 years with a mean value +/- SEM of 9.8 +/- 1.8 years. The cumulative incidence of anastomotic aneurysm at 20 years was 12.0%. Systemic inflammation or steroid administration had little influence on formation of anastomotic aneurysm. Instead, anastomotic aneurysm tended to occur after operations for aneurysmal lesions. CONCLUSIONS: Anastomotic aneurysm can occur anytime after operations for Takayasu's arteritis. The development of anastomotic aneurysm is not influenced by any factor specific to this disease except the presence of an aneurysmal lesion.

Adolescent↗
PubMed1998

Nondissection method for tibial bypass surgery using Esmarch's rubber bandage or an automatic sequential pneumatic tourniquet: long-term results.

It is suspected that operative injury to the native arteries during a vascular bypass procedure causes periarterial fibrosis contributing to late graft failure. A a nondissection method for tibial artery bypass has been developed using Esmarch's rubber bandage or an automatic sequential pneumatic tourniquet. This retrospective study examined patency and other late results in distal bypass operations using the nondissection method. Between June 1982 and July 1995, 78 tibial bypasses were performed using reversed autogenous saphenous vein grafts in 70 patients (57 men, 13 women; mean age 57.4 years). Graft patency was assessed angiographically. When a stenotic lesion was recognized, the graft was revised and considered an assisted primary patency. Primary patency rates at 1, 3, 5, and 10 years were 82.8%, 75.3%, 63.4% and 63.4%, respectively, by life-table analysis. Six grafts required revision for stenosis; one involved distal anastomotic stenosis. As a result, assisted primary patency rates resembled secondary patency rates of 87.7%, 84.3%, 80.3%, and 80.3% at the same respective intervals. In conclusion, the nondissection method improved long-term patency by preventing late distal anastomotic stenosis.

Arterial Occlusive Diseases↗
PubMed1998

Magnetic resonance cisternography for visualization of intracisternal fine structures.

OBJECT: To assess its usefulness in demonstrating cisternal anatomy, the authors investigated magnetic resonance (MR) cisternography in which a heavily T2-weighted turbo spin-echo method was used to visualize normal anatomical fine structures and lesions in the basal cisterns in 20 healthy volunteers and 43 patients. The authors applied peripheral pulse gating, which had been optimized to reduce artifacts in the cisterns attributable to cerebrospinal fluid (CSF) flow. METHODS: The detectability of each cranial nerve was determined in healthy volunteers. The first, second, and third nerves and the seventh-eighth nerve complex were clearly visualized in all participants; the fifth nerve was clearly seen in 80% and the sixth cranial nerve in 50%. The fourth nerve and the ninth through 12th nerves were difficult to identify individually, except in some volunteers. To reduce artifacts caused by fast CSF flow, we determined the delays as a function of the time elapsed between two consecutive peaks of pulse wave in a peripheral pulse gate (P-P interval) at which there was reversal of flow direction to minimize the CSF flow-related artifact. Using peripheral pulse gating and a time delay of 30% of the R-R interval, the authors succeeded in minimizing the CSF flow-related artifacts. Magnetic resonance cisternography appears to be very useful for demonstrating intracisternal fine anatomy and enhancing the contours of the juxtacisternal lesion. A minute amount of CSF interposed between lesions and normal structures such as nerves, vessels, or bone structures can be detected by means of this sequence. In patients with facial spasm, axial images and oblique coronal images obtained in a plane parallel to the seventh-eighth cranial nerve complex demonstrated vascular compression in all 13 patients. The MR cisternography finding of compression was confirmed in all nine patients who underwent microvascular decompression. CONCLUSIONS: Magnetic resonance cisternography appears to show great promise for evaluation of patients with neurovascular compression or tumors in and around the basal cisterns; the procedure adds only a small amount of imaging time.

Adult↗
PubMed1998

Intrauterine high-resolution magnetic resonance imaging in fetal hydrocephalus and prenatal estimation of postnatal outcomes with "perspective classification".

OBJECT: It is possible to diagnose hydrocephalus prenatally based on the morphological appearance of the fetus on neurodiagnostic images; however, the prognosis of this disease shows wide variation. The authors previously proposed a classification system for the prediction of postnatal outcome based on progression of hydrocephalus and affected brain development, known as the "Perspective Classification of Congenital Hydrocephalus (PCCH)." In this study the authors have used their classification system to analyze long-term follow-up results obtained in each clinicoembryological stage of fetal hydrocephalus. METHODS: Sixty-one fetuses with hydrocephalus were examined to predict postnatal outcome by using this newly developed classification. The authors' recently developed method of using heavily T2-weighted imaging with a superconducting magnet clearly delineated the cerebrospinal fluid (CSF) space and the malformed brain and spinal cord. Imaging was achieved in less than 1 second per slice and required no sedation of the fetus. The technique appears to be simple and good at delineating intrauterine anatomy. Hydrocephalus was diagnosed in two fetuses at PCCH embryological Stage I (8-21 gestational weeks), in 28 fetuses at Stage II (22-31 weeks), and in 31 fetuses at Stage III (32-40 weeks). Among these 61 fetuses, clinicopathological typing showed that 19 had primary hydrocephalus (nine in Stage II and 10 in Stage III), 34 had dysgenetic hydrocephalus (two in Stage I, 16 in Stage II, and 16 in Stage III), and eight had secondary hydrocephalus (three in Stage II and five in Stage III). When the hydrocephalic state developed during PCCH Stage I or II, the prognosis was very poor, and only one of 18 fetuses with dysgenetic hydrocephalus and none of three fetuses with secondary hydrocephalus had an acceptable postnatal outcome. Even within the same category or subtype of fetal hydrocephalus, such as primary hydrocephalus in its simple form, or hydrocephalus with spina bifida aperta (myeloschisis), the postnatal outcomes differed depending on the time of onset of hydrocephalus. When the diagnosis of hydrocephalus was made during PCCH Stage II, the fetuses had a poorer postnatal outcome compared with those at Stage III (p < 0.05). CONCLUSIONS: It is emphasized that postnatal prognosis is not simply a function of the form of the diagnosis but is also dependent on the progression of hydrocephalus and the degree to which that process affects neuronal development. Early decompressive procedures, conventionally performed after but, hopefully, performed before birth, are indicated to obtain the optimal postnatal prognosis of fetuses with hydrocephalus diagnosed at PCCH Stage II.

Disease Progression↗
PubMed1998

Tibioperoneal bypass for popliteal arterial occlusion.

OBJECTIVE: To clarify the clinical features of chronic arterial occlusive disease in which the main lesion occurs in the popliteal artery (OPA). EXPERIMENTAL DESIGN: This was a retrospective study with a follow-up of 1 to 163 months. SETTING: A department of surgery in a university hospital. PATIENTS: Fifty-six patient who underwent tibioperoneal bypasses: 31 patients with OPA, and 25 with an extensive occlusive lesion from the femoral to popliteal artery (OFPA). INTERVENTION: All bypasses were performed using reversed saphenous veins under tourniquet ischemia. MEASUREMENTS: The background of the patients and the surgical results, including long-term patency and postoperative arteriographic findings. RESULTS: Buerger's disease occurred most commonly in the OPA group (49%) and arteriosclerosis obliterans occurred most commonly in the OFPA group (64%). The 3-year primary and secondary cumulative patency rates of the grafts for OPA were 72% and 85% respectively, and were comparable with those of OFPA. Arteriographic analyses carried out in the follow-up period revealed no occlusive progression in the inflow artery. CONCLUSIONS: Popliteal-distal bypass is a reliable procedure in selected patients with OPA.

Adult↗
PubMed1998

Continuous hemodiafiltration during aortic arch aneurysm repair in chronic renal failure patient.

We report the successful repair of a distal aortic arch aneurysm in a patient with chronic renal failure following aneurysmectomy for a ruptured abdominal aorta. Perioperative use (during and up to 47 hrs after the operation) of continuous hemodiafiltration was useful for controlling fluid balance and uremia without any complicating hemodynamic instability. However, this should be restricted to the first two or three days after the operation, since it poses risk of significant thrombocytopenia.

Aortic Aneurysm, Thoracic↗
PubMed1998

[Usefulness of enhanced US by CO2 microbubbles for segmental-subsegmental TAE for hepatocellular carcinoma].

Enhanced US by intraarterial infusion of CO2 microbubbles is useful for segmental to subsegmental TAE of hepatocellular carcinoma for several reasons. First, we can obtain better recognition of the tumor stain of hepatocellular carcinoma which is even faint on DSA. Secondly, we can recognize the co-relation between tumor stain and its related segment or subsegment well. Therefore, subsegmental or segmental TAE can be performed easily and precisely using enhanced US by CO2 microbubbles. We noted the bigger advantage of enhanced US by CO2 microbubbles especially in the repeated treated cases of TAE for hepatocellular carcinoma.

Carbon Dioxide↗
PubMed1998

Restricted usage of T-cell receptor Valpha-Vbeta genes in infiltrating cells in the aortic tissue of a patient with atherosclerotic aortic aneurysm.

We report a rare case of an atherosclerotic aortic aneurysm with lymphocyte infiltration in which T-cell receptor (TCR) Valpha as well as Vbeta gene usage was restricted. Immunohistochemical studies showed that the infiltrating cells mainly consisted of macrophages, natural killer (NK) cells, cytotoxic T lymphocytes (CTLs) and T-helper (Th) cells, and that there were almost no infiltrating delta T lymphocytes, and human leukocyte antigen (HLA) class I and 65-kD heat-shock protein (HSP-65) was not strongly expressed in the aortic tissue. Although the immunohistochemical data were consistent with an ordinary atherosclerotic aortic aneurysm, in which TCR Valpha-Vbeta gene usage is known to be polyclonal, the restricted TCR gene usage suggests that a certain autoimmune mechanism was involved in the pathogenesis of this case similar to Takayasu's arteritis, in which massive infiltration of delta T lymphocytes and strong expression of HSP-65 in the aortic tissue are characteristic.

Aged↗
PubMed1997

Rapid postincubation endothelial retention by Dacron grafts.

Defining the most appropriate conditions for strengthening the retention of endothelial cells (ECs) by small-diameter prosthetic endothelialized grafts is indispensable to their clinical application. The incubation time after seeding is one of the most important factors in EC retention. The effects of different postincubation times (0, 2, 4, 8, 16, 24, and 36 hr) on EC monolayers on two different types of graft, fibronectin-coated expanded polytetrafluoroethylene (ePTFE) and collagen-coated knitted Dacron grafts (4 mm x 5 cm) were examined. In situ counting of ECs on the grafts was performed by light microscopy. The percentage cell retention was calculated by dividing the cell counts for grafts exposed to pulsatile flow for 90 min by those for control grafts. To characterize the EC coverage of the grafts, scanning electron microscopy was also performed. The average cell density of control grafts ranged from 5.59 +/- 1.1 to 6.69 +/- 1.5 x 10(4) cells/cm2 and did not differ according to the kind of graft or incubation time. The knitted Dacron grafts showed the maximal cell retention (88 +/- 5%) after incubation for 8 hr, whereas ePTFE grafts did so after 24 hr (83 +/- 6%). Scanning electron microscopic examination after incubation for 8 hr revealed that the density of human ECs on the surfaces of ePTFE and Dacron grafts differed, although there was no morphological difference between the ECs on the two types of graft. Knitted Dacron grafts achieved a high percentage retention in a shorter time than ePTFE grafts.

Blood Vessel Prosthesis↗