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Biomedical subjects

M Uematsu

Publications and source records attributed to M Uematsu.

At least 91 records · Page 5Linked to original sources
PubMed1997

Intravascular ultrasound evidence for importance of plaque distribution in the determination of regional vessel wall compliance.

Regional vessel wall distensibility was determined by measuring luminal area and pressure, using intravascular ultrasound (Sonicath; Boston-Scientific, Watertown, MA, USA; 3.5 Fr, 30 MHz) in 45 left coronary sites from 40 patients. Luminal area in diastole (A) and in systole was measured at the diseased sites. With the ratio of luminal area changes (dA) to coronary pressure changes (dP) during a cardiac cycle, the total distensibility index was calculated by the formula: [(dA/A)/dP] x 10(3). At sites with non-circumferential disease, perimeters in diastole (L) and in systole were measured at the normal and diseased portions, and the changes in perimeters (dL) during a cardiac cycle were calculated. The regional distensibility index was obtained by the formula: [(dL/L)/dP] x 10(3). In 22 sites with circumferential disease, the total distensibility index was 1.03 +/- 0.61/mmHg, significantly lower than that for 23 sites with non-circumferential disease (1.45 +/- 0.89/mmHg; P < 0.05). In non-circumferential disease, the regional distensibility index at the diseased portion was significantly lower (0.33 +/- 0.47/mmHg) than that at the normal portion (1.11 +/- 0.75/mmHg; P < 0.01). Coronary sites with residual non-circumferential disease after angioplasty also exhibited heterogeneity of regional distensibility (0.73 +/- 0.76 at disease sites versus 1.58 +/- 0.95/mmHg at normal sites, n = 10, P < 0.05). These results indicate that heterogeneous regional wall distensibility exists at sites with non-circumferential disease where the total vessel distensibility is preserved by the presence of compliant normal portion. This heterogeneity of regional wall distensibility may represent a biomechanical factor that explains the mechanism of plaque rupture that occurs mainly at the shoulder of the non-circumferential disease.

Biomechanical Phenomena↗
PubMed1996

A dual computed tomography linear accelerator unit for stereotactic radiation therapy: a new approach without cranially fixated stereotactic frames.

PURPOSE: To perform stereotactic radiation therapy (SRT) without cranially fixated stereotactic frames, we developed a dual computed tomography (CT) linear accelerator (linac) treatment unit. METHODS AND MATERIALS: This unit is composed of a linac, CT, and motorized table. The linac and CT are set up at opposite ends of the table, which is suitable for both machines. The gantry axis of the linac is coaxial with that of the CT scanner. Thus, the center of the target detected with the CT can be matched easily with the gantry axis of the linac by rotating the table. Positioning is confirmed with the CT for each treatment session. Positioning and treatment errors with this unit were examined by phantom studies. Between August and December 1994, 8 patients with 11 lesions of primary or metastatic brain tumors received SRT with this unit. All lesions were treated with 24 Gy in three fractions to 30 Gy in 10 fractions to the 80% isodose line, with or without conventional external beam radiation therapy. RESULTS: Phantom studies revealed that treatment errors with this unit were within 1 mm after careful positioning. The position was easily maintained using two tiny metallic balls as vertical and horizontal marks. Motion of patients was negligible using a conventional heat-flexible head mold and dental impression. The overall time for a multiple noncoplanar arcs treatment for a single isocenter was less than 1 h on the initial treatment day and usually less than 20 min on subsequent days. Treatment was outpatient-based and well tolerated with no acute toxicities. Satisfactory responses have been documented. CONCLUSION: Using this treatment unit, multiple fractionated SRT is performed easily and precisely without cranially fixated stereotactic frames.

Brain Neoplasms↗
PubMed1996

Entire hemithorax irradiation following complete resection in patients with stage II-III invasive thymoma.

PURPOSE: To evaluate the feasibility and efficacy of prophylactic entire hemithorax irradiation (EH) in addition to mediastinal irradiation (MRT) following a complete resection in Stage II-III invasive thymoma. METHODS AND MATERIALS: Forty-three patients with invasive thymoma treated with surgery and radiation therapy between 1978 and 1993 were analyzed retrospectively. All 43 patients underwent a complete surgical resection and were judged to have Masaoka's Stage II-III invasive thymoma. Of these, 23 patients received EH and MRT (EH-MRT) and the remaining 20 received MRT. Of the 23 patients with EH-MRT, 11 were Stage II and 12 Stage III. Of the 20 with MRT, 11 were Stage II and 9 Stage III. In most cases, EH was 15 Gy per 15 fractions over 3 weeks (without lung compensation calculation). In both the EH-MRT and MRT group, the total radiation doses to the mediastinum were similar with a median of 40 Gy. The median follow-up time after surgery was 63 months and no patients were lost to follow-up. RESULTS: Only one of the 23 patients with EH-MRT relapsed. On the other hand, eight of the 20 with MRT relapsed, six of whom died of disease. The pleura was the most common site of failure. At 5 years, the relapse-free rate was 100% for those receiving EH-MRT and 66% for those with MRT (p = 0.03); the overall survival rate was 96% for those with EH-MRT, and 74% for those with MRT (p: not significant). The only significant treatment-related complication was radiation pneumonitis requiring treatment, in one patient who received MRT and three who received EH-MRT, including one death of a 72-year-old man and one 68-year-old woman with severe lung fibrosis. CONCLUSION: Except for elderly patients, EH-MRT following a macroscopically complete resection appears to be safe and feasible, and can reduce intrathoracic relapses.

Adult↗
PubMed1996

Endothelins contract guinea-pig pulmonary artery and enhance its adrenergic response via ET(A) receptors.

1. This study has pharmacologically characterized endothelin (ET) receptor subtype(s) mediating contraction and enhancement of adrenergic contraction in guinea-pig pulmonary artery. Isometric tension of the isolated endothelium-denuded ring preparations was measured in the presence of indomethacin (10(-5) mol/L) and N(G)-nitro-L-arginine methyl ester (L-NAME; 3 x 10(4) mol/L) to exclude a mechanism via endothelium, cyclo-oxygenase-generated eicosanoids and nitric oxide. 2. In the additional presence of tetrodotoxin (TTX; 3 x 10(-7) mol/L), ET-1 (10(-11)-10(-7) mol/L) concentration-dependently contracted the preparations. The rank order of potency to contract the preparations among ET receptor agonists was ET-1, sarafotoxin (STX)6b > ET-3 > IRL 1620, STX 6c. BQ-123 (7 x 10(-7)-7 x 10(-6) mol/L) concentrations-dependently shifted the concentration-contraction curve for ET-1 to the right in a parallel manner. Pretreatment with STX 6c (3 x 10(-7) mol/L for 30 min) did not significantly desensitize contractions to ET-1, ET-3 or IRL 1620 (P > 0.05; t-test, 10 d.f). 3. ET-1 (10(-10)-10(-9) mol/L) and STX 6b (10(-9)-10(-8) mol/L) significantly enhanced the electrical field stimulation-induced contraction in a BQ-123-sensitive manner (P < 0.05: t-test, 24-38 d.f), while ET-3 (10(-11)-10(-8) mol/L) and STX 6c (10(-11)-10(-7) mol/L) did not affect contractions. ET-1 (10(-11) mol/L) significantly enhanced contractions to exogenous noradrenaline in the presence of TTX (3 x 10(-7) mol/L) (P < 0.05; t-test, 16 d.f.). 4. These data indicate that the BQ-123-sensitive ET(A) receptor mediates both contraction and enhancement of adrenergic contractions in the guinea-pig pulmonary artery.

Animals↗
PubMed1996

Surgical treatment of refractory venous stasis ulcer due to a severe impairment of calf muscle pump function: evaluation by air plethysmography. A case report.

The authors encountered a forty-nine-year-old man with a lower limb ulcer refractory to intensive conservative therapy. No varicose vein was found anywhere, and the usual phlebographies and foot venous pressure measurement failed to diagnose it as a venous stasis ulcer. A direct phlebography method developed by the authors, in which a thin catheter is inserted into the deep vein, disclosed a reflux of the popliteal vein or a deep muscle branch from which an incompetent perforator arose toward the superficial vein above the ulcer. Air plethysmography (APG) showed a severe impairment of the calf muscle pump function. He underwent a subfascial ligation of two incompetent perforators together with a stripping of the great saphenous vein passing under the ulcer. Postoperatively, this ulcer was cured in an early phase, and the calf muscle pump function showed improvement in the APG.

Hemodynamics↗
PubMed1996

Does bone SPECT actually have lower sensitivity for detecting vertebral metastasis than MRI?

UNLABELLED: We compared the ability of bone SPECT and MRI to detect vertebral metastasis. METHODS: Skeletal scintigraphy, including planar and SPECT imaging, and spinal MRI examinations, were performed in 22 cancer patients in whom a total of 88 metastatic foci and 12 degenerative joint disease lesions were detected. Metastatic foci were defined as lesions that suggested metastasis on MRI and/or bone destruction on radiographs or CT and/or aggravation of increased tracer uptakes on serial bone scans. Image reconstruction of axial, coronal and sagittal sections was processed in a 128 X 128 matrix. MRI studies were performed with a 1.5 tesla signal scanner using fast spin-echo sequences. T1- and T2-weighted images were obtained in the sagittal plane. RESULTS: Twenty patients had at least one vertebral metastasis. MRI diagnosed 86 of the 88 (97.7%) metastatic foci; bone SPECT correctly diagnosed 81 of 88 (92.0%); and planar imaging detected 62 of 88 (70.4%). The two vertebrae with metastasis not detected by MRI were clearly seen by bone SPECT. Extra-vertebral body metastases (e.g. in the pedicle, lamina, transverse and spinous processes) were, however, most often detected by SPECT, followed by MRI and planar imaging (40 versus 32 versus 4). CONCLUSION: Vertebral SPECT, using high-resolution SPECT equipment, produced excellent results that were comparable to and complementary with MRI in detecting vertebral metastasis. Our data suggest that vertebral SPECT is superior to MRI in detecting extra-vertebral body metastasis.

Adolescent↗
PubMed1996

[Palliation of brain metastases: factors associated with survival].

One hundred ten patients with brain metastases (76 lung cancer, 11 breast cancer, 7 colorectal cancer and others) were treated with radiotherapy, and the results were retrospectively evaluated. Neurologic symptoms were improved in 66% of patients. The relationship between improvement of neurologic symptoms and several factors, including irradiation dose, primary lesion, histology, term between first treatment and recurrence, clinical symptoms and CT findings, was analyzed. There was no significant correlation between symptom relief and these factors except for the number of metastatic lesions. Four of 110 patients could survive more than 2 years after radiotherapy: one with lung cancer, one with breast cancer, one with rectum cancer and one with uterine cancer. The factors that were analyzed for symptom relief were also studied to determine their effect on the survival of lung cancer patients with brain metastases. The patients who had higher dose irradiation (50 Gy) of improvement of neurological symptoms after radiotherapy survived significantly longer than those who had 30 Gy of irradiation or no symptom relief. Multivariate analysis of these factors showed that improvement of symptoms and irradiation dose were similarly important prognostic factors, whereas the others were not correlated with survival.

Brain Neoplasms↗
PubMed1996

[A case of intrathoracic goiter].

Intrathoracic goiter is an uncommon conditional lesion. A case of intrathoracic goiter in a 66-year-old woman is herein described. Her chief complaint was anterior chest opplession. A computed tomographic scan and magnetic resonance imaging (MRI) revealed intrathoracic goiter pressed the trachea to the right side. The tumor was safety and completely took by collar incision without thoracotomy. Histologically, the mass was diagnosed the adenomatous goiter. In this case, MRI was very useful to be determined the surgical approach.

Aged↗
PubMed1996

[Prognostic factors of nasopharyngeal carcinoma treated by radiotherapy].

This study was a retrospective analysis of 82 patients with histologically confirmed nasopharyngeal carcinoma, who were treated at Keio University Hospital from March 1983 to March 1993. We studied all cases(62% of them were stage IV) with regard to their prognostic factors and chronic side effects induced by radiation. All patients were received extended-field radiotherapy from the base of the skull to the supraclavicular lymph node area. The five- and ten-year overall survival rates for the entire group were 59% and 49%, respectively. Three stage I patients were alive without recurrence or metastases for more than 5 years. The ten-year survival rate stage II-III for patients (23 patients) was 78%, and for stage IV (56 patients) 37%. The five-year survival rate of patients in T2-3 group without lymph node metastasis was 88%, while it was reduced to 55% for patients with metastasis. The prognosis of T4 patients was very poor: their five-year survival rate was 37% with lymph node metastasis, and 35%, without lymph node metastasis. Patients under 46 years old showed an increased survival rate compared with patients over 46 years old. Patients who completed less than 52 days of radiation therapy found to have a better prognosis than those receiving radiation for a longer period. Our multivariate analysis indicated that age, radiation period and N-factor were statistically significant in influencing prognosis. Hearing loss occurred relatively high with 20% of cumulative incidence in our study, probably because they received radiation therapy with the extended field including bilateral middle and inner ear. Extended-field radiotherapy for patients with nasopharyngeal carcinoma might contribute to improving their cure-rate, and precise radiation planning is warranted to avoid the late complications such as hearing loss.

Adenocarcinoma↗
PubMed1996

Experimental studies on modified human ureter as an arterial substitution for reconstruction of small caliber vessels.

Human ureters were experimentally employed as vascular biografts for small-caliber vessels. They were produced by tanning with polyepoxy compound or glutaraldehyde, and also were compared with saphenous veins tanned by polyepoxy compound and/or ready-made vascular graft of polytetrafluoroethylene (e-PTFE). These produced grafts, which had enough elasticity and excellent durability were successfully implanted to the carotid arteries in Japanese white rabbits. The grafts were sacrificed after 1 month observation. In this model there were no evidence of rejection, aneurysmal formation and/or infection. Polyepoxy compound fixed human ureter (n = 6), polyepoxy compound fixed saphenous vein (n = 6) and e-PTFE (n =3) showed good patency, but all glutaraldehyde fixed human ureters (n = 3) were completely occluded with severe intimal hyperplasia. Especially, polyepoxy compound fixed human ureter showed excellent patency as well as function, and the histological findings revealed monolayer endothelial cells covering the surface of the graft. No intimal hyperplasia was demonstrated at the anastomotic site. This study suggested that the polyepoxy compound fixed human ureter could serve as a satisfactory blood conduit of reconstruction for the small caliber vessels. Our preliminary data also suggests that longer observation up to 6 months in polyepoxy compound fixed human ureter graft and 18 months in polyepoxy compound fixed saphenous vein graft after surgery, arteriovenous shunt (A-V shunt), long bypass with a graft length of 2 to 5 cm), Y-graft model, sequential model and reinforcement graft by dacron cloth give good results.

Arteries↗
PubMed1995

Different modes of sensory neuropeptides and nitric oxide involvement in relaxation of guinea-pig vessels.

This study investigated involvement of calcitonin-gene-related peptide (CGRP), substance P (SP) and nitric oxide (NO) in transmural nerve stimulation (TNS)-induced non-adrenergic, non-cholinergic (NANC) relaxation in isolated guinea pig anterior mesenteric artery (AMA) and posterior caval vein (PCV). Effects of cyclo-oxygenase-generated eicosanoids were blocked with indomethacin (10(-5) M) and so were adrenergic and cholinergic responses with phentolamine (3 x 10(-6) M), propranolol (10(-6) M) and atropine (10(-6) M). In both vessels precontracted by U-46619, TNS induced relaxation, which was almost completely abolished by capsaicin pretreatment (10(-6) M, 15 minutes). In AMA, a CGRP1 receptor antagonist (human CGRP8-37, 10(-5) M) significantly attenuated the relaxation, while did both human CGRP8-37 (10(-5) M) and neurokinin-1 receptor antagonists (spantide, 2 x 10(-5) M and FK888, 3 x 10(-6) M) in PCV. NG-nitro-L-arginine methyl ester (10(-4) M) did not significantly attenuate either the NANC-or CGRP-induced relaxation in AMA. However, it significantly did attenuate both the NANC-and SP-induced relaxation, and it also considerably attenuated CGRP-induced relaxation although insignificantly, in PCV. Thus, CGRP could be significantly responsible for the NO-independent NANC relaxation in AMA, whereas both CGRP and SP could additionally relax PCV in a NO-dependent manner.

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗
PubMed1995

New method for evaluating left ventricular wall motion by color-coded tissue Doppler imaging: in vitro and in vivo studies.

OBJECTIVES: The aim of this study was to examine the accuracy and validity of a newly developed tissue Doppler imaging system in in vitro and in vivo studies. BACKGROUND: Because quantitative measurement of wall motion velocity in real time is still difficult by conventional echocardiography, we developed a new system for evaluating ventricular wall motion by analyzing Doppler signals from cardiac tissue. METHODS: We used a modified Doppler color imaging system, omitting the high pass filter to allow Doppler signals from cardiac tissue to enter the auto-correlator. Ultrasound carrier and pulse repetition frequencies were 3.75 MHz and 3.0 to 6.0 kHz, respectively. Under these conditions, the lowest measurable velocity was 0.2 cm/s. RESULTS: In the rotating sponge model, the measured velocity correlated well with the actual velocity (y = 0.97x + 2.17, r = 0.99). In clinical settings, the mid-ejection mean velocity at either endocardial or epicardial sites of the left ventricular posterior wall measured by M-mode tissue Doppler imaging correlated well with that measured by conventional M-mode echocardiography (y = 0.94x + 0.64, r = 0.99). During systole, in healthy subjects, the anterior left ventricular wall was color-coded blue and the posterior wall was color-coded red, whereas the akinetic regions associated with myocardial infarction showed no color throughout the cardiac cycle. The ventricular posterior wall excursion velocity, defined as the difference between velocities at the endocardial and epicardial sites, was significantly slower in patients with dilated cardiomyopathy (0.4 +/- 0.3 cm/s) than in normal subjects (2.0 +/- 0.6 cm/s). CONCLUSIONS: These results indicate that the present system accurately represents tissue velocity and can create two-dimensional color images that facilitate visual assessment of ventricular wall motion.

Adult↗
PubMed1995

Myocardial velocity gradient as a new indicator of regional left ventricular contraction: detection by a two-dimensional tissue Doppler imaging technique.

OBJECTIVES: This study was performed to assess a new indicator of regional left ventricular contraction determined by a two-dimensional tissue Doppler imaging technique. BACKGROUND: Recent studies have demonstrated that instantaneous tissue motion velocity can be noninvasively assessed by tissue Doppler imaging. However, quantitative assessment of regional left ventricular contraction is still difficult because of the effects of the Doppler angle of incidence and parallel motion of the whole heart. METHODS: We assessed left ventricular wall motion in 11 normal subjects, 14 patients with an old myocardial infarction (anteroseptal in 7, posterior in 7) and 8 patients with dilated cardiomyopathy. Tissue Doppler velocity was corrected by the Doppler angle of incidence after the hypothetical center of contraction was set. Subsequently, the myocardial velocity gradient between the endocardium and epicardium was determined from the velocity profile along each radial line from the center of contraction by using least squares linear regression. RESULTS: In normal subjects, peak myocardial velocity gradient was lower in the anteroseptal wall (mean [+/- SD] 1.69 +/- 0.53 s-1) than in the posterior wall (3.28 +/- 0.67 s-1, p < 0.01). Myocardial velocity gradient in the infarct regions was significantly lower (anteroseptal 0.58 +/- 0.41 s-1, p < 0.05; posterior 0.17 +/- 0.27 s-1, p < 0.01) than that in normal subjects as well as that in the corresponding noninfarct regions (2.84 +/- 0.37 s-1 and 1.48 +/- 0.25 s-1, p < 0.01, respectively). In patients with dilated cardiomyopathy, myocardial velocity gradient was generally lower (anteroseptal 0.72 +/- 0.59 s-1; posterior 0.93 +/- 0.67 s-1) than that in normal subjects (p < 0.01). CONCLUSIONS: These results demonstrate that regional left ventricular contraction can be quantitatively assessed by the myocardial velocity gradient derived from two-dimensional tissue Doppler imaging. We suggest that myocardial velocity gradient has potential for the quantitative assessment of regional left ventricular contraction abnormalities in patients.

Adult↗
PubMed1995

Coexistent myelodysplastic syndrome and non-Hodgkin lymphoma. Report of a case and review of the literature.

The patients with a hematopoietic neoplasm can develop myelodysplastic syndrome following chemotherapy. We report herein a case of non-Hodgkin B-cell lymphoma and refractory anemia with ringed sideroblasts. Absence of the preceding chemotherapy establishes the true coincidence of the two disorders. We review 25 similar cases reported in the last 11 years and discuss the possible etiology of coexistence.

Aged↗
PubMed1995

Intraarterial infusion of dibutyryl cyclic adenosine monophosphate plus mitomycin C for unresectable hepatocellular carcinoma: long-term survival and response to tumor growth inhibition.

RATIONALE AND OBJECTIVES: Dibutyryl cyclic adenosine 3',5'-monophosphate (dBcAMP) has the capacity to promote morphologic differentiation and to inhibit tumor growth in vitro, but it has not been well researched in the clinical setting. In this study we examined the effects of intraarterial infusion of dBcAMP plus mitomycin C (MMC) on long-term survival and growth inhibition of tumors. METHODS: Thirty-one previously untreated patients with unresectable hepatocellular carcinoma (HCC) received intraarterial infusion of dBcAMP plus MMC. According to the International Union Against Cancer staging system, three patients had stage T3, eight had stage T4a, and 20 had stage T4b cancer. Growth inhibition was defined as no computed tomography (CT) scan evidence of increase in tumor diameter for at least 6 months after treatment. RESULTS: In all 31 patients with HCC, the cumulative survival rate was 34% at 1 year, 14% at 3 years, and 9% at 5 years. The median survival was 5.0 months, with the longest survival period being 92 months. Among 21 patients in whom a tumor response could be evaluated on the basis of follow-up CT studies, two had complete regression of their primary tumors. Overall, the response rate was 43% (9 of 21). Among the 12 stage T4b patients who had HCC that included the main trunk and its major branches of the portal vein, portal thrombi had disappeared in four (33%). Among eight patients who survived more than 1 year and were evaluated for tumor response using follow-up CT scan studies, six (75%) had growth inhibition of tumor. CONCLUSION: Chemotherapy combined with dBcAMP and MMC showed a favorable response in approximately one third of 31 patients who had unresectable HCC. Because of our results, combined therapy should be strongly considered in the treatment of patients with HCC including occlusion of the main portal vein.

Antibiotics, Antineoplastic↗
PubMed1995

Regulation of endothelial cell nitric oxide synthase mRNA expression by shear stress.

Shear stress enhances expression of Ca(2+)-calmodulin-sensitive endothelial cell nitric oxide synthase (ecNOS) mRNA and protein in bovine aortic endothelial cells (BAEC). The present studies were performed to investigate mechanisms responsible for regulation of ecNOS mRNA expression by shear stress and to determine if this induction of ecNOS mRNA is accompanied by an enhanced nitric oxide (NO) production. Shear stresses of 15 dyn/cm2 for 3-24 h resulted in a two- to threefold increase of ecNOS mRNA content quantified by Northern analysis in BAEC. Shear stresses (1.2-15 dyn/cm2) for 3 h resulted in an induction of ecNOS mRNA in a dose-dependent manner. In human aortic endothelial cells, shear stresses of 15 dyn/cm2 for 3 h also resulted in ecNOS mRNA induction. In BAEC, this induction in ecNOS mRNA was prevented by coincubation with actinomycin D (10 micrograms/ml). The K+ channel antagonist tetraethylammonium chloride (3 mM) prevented increase in ecNOS mRNA in response to shear stress. The ecNOS promotor contains putative binding domains for AP-1 complexes, potentially responsive to activation of protein kinase C (PKC). However, selective PKC inhibitor calphostin C (100 nM) did not inhibit ecNOS induction by shear stress. Finally, production of nitrogen oxides under both basal conditions and in response to the calcium ionophore A-23187 (1 microM) by BAEC exposed to shear stress was increased approximately twofold compared with cells not exposed to shear stress. These data suggest that ecNOS mRNA expression is regulated by K+ channel opening, but not by activation of PKC, and that shear not only enhances ecNOS mRNA expression but increases capacity of endothelial cells to release NO.

Animals↗