Search PubMed⌕ Search

Biomedical subjects

T Misaki

Publications and source records attributed to T Misaki.

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

On-line assessment of regional ventricular wall motion by transesophageal echocardiography with color kinesis during minimally invasive coronary artery bypass grafting.

OBJECTIVE: Our objective was to determine the changes in regional ventricular wall motion during minimally invasive direct coronary artery bypass grafting by color kinesis using transesophageal echocardiography. METHODS: Minimally invasive coronary artery bypass grafting was performed in 34 patients, during which transesophageal echocardiography was used. Thirteen patients had isolated disease of the left anterior descending artery. Regional ventricular wall motion was analyzed by color kinesis with the SONOS 2500 transesophageal echocardiograph (Hewlett-Packard Co, Andover, Mass). On-line assessment of regional wall motion was continued during the operation. RESULTS: Wall motion abnormalities during ischemia were present in 4 cases, left ventricular mid-anterior hypokinesis in 3 cases, and left ventricular apical-lateral hypokinesis in 1 case. In all cases, wall motion was maintained after bypass. In patients with total coronary occlusion, changes in wall motion did not occur during anastomosis. CONCLUSIONS: Color kinesis allowed us to evaluate the change in regional ventricular wall motion induced by myocardial ischemia during minimally invasive coronary artery bypass grafting both objectively and quantitatively.

Aged↗
PubMed1999

Mediastinal lymph node metastasis model by orthotopic intrapulmonary implantation of Lewis lung carcinoma cells in mice.

This study is designed to establish a pulmonary tumour model to investigate the biology and therapy of lung cancer in mice. Current methods for forming a solitary intrapulmonary nodule and subsequent metastasis to mediastinal lymph nodes are not well defined. Lewis lung carcinoma (LLC) cell suspensions were orthotopically introduced into the lung parenchyma of C57/BL6 mice via a limited skin incision without thoracotomy followed by direct puncture through the intercostal space. The implantation process was performed within approximately 50 s per mouse, and the operative mortality was less than 5%. Single pulmonary nodules developed at the implanted site in 93% of animals and subsequent mediastinal lymph node metastasis was observed in all mice that formed a lung nodule after intrapulmonary implantation. The size of tumour nodule and the weight of mediastinal lymph node increased in a time-dependent manner. The mean survival time of mice implanted successfully with LLC cells was 21+/-2 days (range 19-24 days). Histopathological analysis revealed that no metastatic tumour was detectable in the mediastinal lymph nodes on day 11, but metastatic foci at mediastinal lymph nodes were clearly observed on days 17 and 21 after implantation. Other metastases in distant organs or lymph nodes were not observed at 21 days after the implantation. Comparative studies with intrapleural and intravenous injections of LLC cells suggest that the mediastinal lymph node metastasis by intrapulmonary implantation is due to the release of tumour cells from the primary nodule, and not due to extrapulmonary leakage of cells. An intravenous administration of cis-diamine dichloro platinum on day 1 after tumour implantation tended to suppress the primary tumour nodule and significantly inhibited lymph node metastasis. Thus, a solitary pulmonary tumour nodule model with lymph node metastasis approximates clinical lung cancer and may provide a useful basis for lung cancer research.

Animals↗
PubMed1999

Comparison of serum thyrotrophin concentrations determined by a third generation assay in patients with various types of overt and subclinical thyrotoxicosis.

OBJECTIVE: Recent increases in the sensitivity of methods used to measure TSH, especially third generation assays, have enabled separation of partial from complete pituitary suppression in patients with thyrotoxicosis. We have investigated the use of a sensitive chemiluminescent enzymeimmunoassay in the differential diagnosis of thyrotoxicosis. DESIGN AND PATIENTS: Serum TSH concentrations were determined by chemiluminescent enzymeimmunoassay in patients with various types of overt and subclinical thyrotoxicosis. RESULTS: The assay was highly sensitive with an analytical sensitivity of 0.0016 mU/l. Among 45 hyperthyroid patients with untreated Graves' disease, 37 (82.2%) showed undetectably low levels (< 0.002 mU/l). Serum TSH in the remaining 8 patients (17.8%) was 0.003-0.005 mU/l. In contrast, TSH was undetectably low in only 5 (20.0%) of 20 patients with painless thyroiditis and in 2 (12.5%) of 16 patients with subacute thyroiditis. Eleven (55.0%) with painless thyroiditis and 12 (75.0%) with subacute thyroiditis had TSH values greater than 0.005 mU/l (0.006-0.032 and 0.006-0.228 mU/l, respectively; normal range 0.5-5.0 mU/l). Serum TSH levels were subnormal in 10 of 12 patients with euthyroid ophthalmic Graves' disease, including 4 with undetectably low levels. Among 11 patients with an autonomously functioning thyroid nodule 6, including 1 with normal free T4 and free T3 and 2 with normal free T3, showed TSH values less than 0.002 mU/l. No significant correlation was observed between serum free T4 or free T3 and TSH concentrations in thyrotoxic patients. Together with the incomplete suppression of TSH observed in those with destructive thyroiditis, this suggests that the grade of TSH suppression was influenced by the duration of illness at the time of blood sampling. CONCLUSION: The third-generation TSH assay is useful for the differential diagnosis of various types of thyrotoxicosis, especially between Graves' disease and destructive thyroiditis.

Adult↗
PubMed1999

Goiter associated with acromegaly: sonographic and scintigraphic findings of the thyroid gland.

Elevation in serum human growth hormone (GH) level is known to be a factor that causes goiter development. The present study was designed to analyze sonographic and scintigraphic appearances of the thyroid in patients with acromegaly. The records of 48 consecutive patients with acromegaly were examined. Two patients had a history of operation for thyroid cancer. One had an atrophic thyroid gland after 131I treatment for Graves' disease. Goiter was palpable in 39 of the remaining 45 patients. Neither ultrasonography (US) nor scintigraphy was performed in 17 patients, including 6 with no palpable goiter and 11 with small diffuse goiter (group 1). Of the remaining 28 patients who underwent US, 14 had a moderately or markedly enlarged diffuse goiter (group 2), 13 were diagnosed as having adenomatous goiter (group 3), and 1 had a solitary cystic nodule. Among 11 patients in group 3 who underwent 123I or 99mTc thyroid scintigraphy, 6 showed uneven uptake, and 2 with undetectably reduced levels of thyrotropin (TSH) showed localized functioning areas. The mean serum TSH concentration in group 3 was significantly lower than that in group 1 or 2 (p<0.01). The duration of illness as acromegaly was significantly longer in group 2 and 3 as compared with group 1 (p<0.05). These results suggest that long-term stimulation by GH and insulin-like growth factor-I of thyroid follicular cells might be responsible for thyroid enlargement, presence of functioning lesions, slight overactivity of the thyroid, and the subsequent formation of multiple nodules in acromegalic patients. In conclusion, excluding two patients with thyroid cancer and one with Graves' disease, goiter was palpable in 39 of the 45 patients with acromegaly, among whom 14 (13 adenomatous goiters and 1 solitary cystic nodule) showed nodular enlargement.

Acromegaly↗
PubMed1999

Rapid progression of pituitary hyperplasia in humans with primary hypothyroidism: demonstration with MR imaging.

PURPOSE: To use magnetic resonance (MR) imaging to evaluate the morphologic changes of the pituitary gland during the development of hypothyroidism. MATERIALS AND METHODS: Fourteen patients who had undergone thyroidectomy were evaluated before radioactive iodine 131 therapy. In each patient, MR imaging and measurement of serum hormone levels were performed twice: 5 weeks before 131I treatment as the "euthyroid state" with thyroid hormone supplementation and on the day of 131I treatment as the "hypothyroid state" after a 3-week depletion of thyroid hormone supplements. Nine healthy volunteers also underwent MR imaging twice at an interval of 5 weeks. Pituitary volume and the relative signal intensity ratio of the anterior pituitary to the pons were measured. The shape and signal intensity of the pituitary gland were also visually assessed. The paired Student t test was used to evaluate the significance of the data. A P value less than .05 indicated a statistically significant difference. RESULTS: The patients had significantly larger pituitary volume in the hypothyroid state than in the euthyroid state both quantitatively (P < .001) and visually. No significant differences were found in the relative signal intensity ratios of the anterior pituitary to the pons. In healthy volunteers, no significant differences in pituitary volumes or signal intensity were found between the two MR images. CONCLUSION: Rapid progression of hyperplasia of the anterior pituitary may occur with acute development of hypothyroidism.

Adult↗
PubMed1999

[New operative technique to resect of peripheral bronchogenic carcinoma with chest wall invasion using Kent's retractor].

We report the new operative technique for resection of peripheral bronchogenic carcinoma with chest wall invasion using Kent's retractor and hook suspender. Standard muscle sparing thoracotomy cannot obtain the adequate operative field in the posterior chest wall under the scapula because of sparing the latissimus dorsi muscle. To obtain a sufficient operative field at the operation for en bloc chest wall resection, especially with the area of the posterior chest wall under the scapula, resection of the trapezius muscle, rhomboideus major muscle, and latissimus dorsi muscle has been added to muscle-sparing thoracotomy. Through our new technique using Kent's retractor and hook suspender that has been used in the abdominal surgery, assistant surgeon can be eliminated in favor of hanging up the scapula, which is able to be performed much easier to obtain a good operative field. To use the Kent's retractor and hook suspender, the scapula is lifted upward and cranially. With these procedures, the proximal portion of the first, second and third ribs in the posterior chest wall covering by the scapula is able to resect from vertebrocostal junction with muscle-sparing thoracotomy. We examined the apparatus for a case of the right upper lung carcinoma with invasion to the posterior chest wall. We performed right upper lobectomy with chest wall in the area of the second, third and forth ribs with suspending the scapula by Kent's retractor after muscle-sparing thoracotomy.

Adenocarcinoma↗
PubMed1999

[Cases of sternal metastasis except from breast cancer].

Surgical resection is the option for sternal metastasis from breast cancer. But surgical treatment is the subject of controversy for sternal metastasis except from breast cancer. Four cases of secondary malignant tumors of the sternum except from breast cancer were reported. Primary lesions included thyroid cancer, gastric cancer, malignant fibrous histiocytoma of the chest wall and multiple myeloma. In 3 cases, operation were done and they survived 11 months, 13 months and 3 years respectively. In case of secondary malignant tumor of the sternum except from breast cancer, surgical treatment should be considered.

Aged↗
PubMed1998

Surgical Procedure for Right Anteroseptal Accessory Conduction Pathways in Wolff-Parkinson-White Syndrome.

In patients with Wolff-Parkinson-White syndrome, the right anteroseptal accessory conduction pathway is rare, and exists from the atrium to the ventricle in close anatomic proximity to the normal atrioventricular conduction system. Catheter ablation of this lesion is reported to interrupt atrioventricular node-His bundle conduction more easily than that of other lesions. At our institute, there were 10 patients with right anteroseptal accessory conduction pathway among 454 patients (2.2%) who underwent the surgical division of the accessory pathway. Our procedure involved the the endocardial approach with knife dissection and cryocoagulation. With the heart beating under normothermal cardiopulmonary bypass, delta wave disappearance was easily noted. Neither complete atrioventricular block nor recurrent conduction occurred. Cryoablation used by our endocardial surgical division, is a safe and accurate procedure.

Journal Article↗
PubMed1998

Pathological Analysis of the Radial and Internal Thoracic Artery.

To evaluate the usefulness of the radial artery (RA) as a graft material for coronary artery bypass grafting (CABG), histologic studies of the RA were performed and compared with the internal thoracic artery (ITA). Specimens were obtained from both ends of 12 RAs and the distal side of the ITA during the operation. The degree of arteriosclerosis was evaluated using an NIH Image 1.57 system. The pathological index of arterioslerotic change was expressed as the ratio of cross-section (Rx: internal luminal area/tunica media area). The mean arteriosclerotic ratio (Rx) of the 12 proximal sides of the RA specimens was 0.18 +/- 0.03, the 12 distal sides 0.27 +/- 0.17, and the 12 ITAs was 0.14 +/- 0.05, respectively. There was significant difference between the distal side of the RA and the ITA. The distal side of the RA was a little greater than the proximal, but there was no significant difference between the proximal side of the RA and the ITA. From the microscopic findings, the tunica media of the RA is poor in elastic fibers and rich in smooth muscle cells compared with the ITA. The internal elastic lumina of the RA is developed as well as the ITA, but more calcification was found in the distal RA than in the others. According to these results, although care must be taken for arteriosclerosis of the distal RA, it can be expected to be a suitable bypass material for CABG.

Journal Article↗
PubMed1998

A Dumon stent inserted for bronchial stenosis causing a left bronchopericardial fistula: report of a case.

We present herein the case of a 59-year-old man in whom a Dumon stent, inserted as treatment for stenosis of the left main bronchus, caused a left bronchopericardial fistula. The patient initially presented with severe dyspnea caused by main bronchial stenosis of unknown origin for which a Dumon stent was inserted at a local hospital. The Dumon stent migrated to the endobronchus through the stenosis of the left main bronchus a few days later, and his dyspnea remained unresolved. He was subsequently referred to our department 6 months later, where a left pneumonectomy under supportive cardiopulmonary bypass through the femoral artery and vein was performed, and a postoperative pathological diagnosis of bronchial leiomyosarcoma was made. For this rare group of malignant tumors, early diagnosis permits complete surgical resection of the mass and offers the best prognosis. Excision of the tumor should be performed under cardiopulmonary bypass through the femoral vessels when a risk of sudden rupture of the pulmonary artery or vein exists for any reason.

Bronchi↗
PubMed1998

Internal jugular vein malformation with mature adipose deposits in the mediastinum.

Anomalies of the internal jugular vein are uncommon and not frequently experienced. Either a fusiform or saccular dilatation of the veins has been termed phlebectasia by some investigators and venous aneurysm by others. In 1928 Harris was the first to describe this condition using the term "congenital venous cyst." Relatively few cases of head and neck venous aneurysms have since been reported. We herein report a case of congenital internal jugular vein malformation while discussing both the diagnosis and pathology.

Adipose Tissue↗
PubMed1998

Effect of assisted circulation on left ventricular performance in a canine model.

BACKGROUND: Little is known about left ventricular performance during venoarterial bypass and left heart bypass (LHB) after cross-clamping the descending thoracic aorta. We evaluated the effects of venoarterial bypass and LHB on ventricular load optimization and left ventricular work efficiency. METHODS: We used the left ventricular conductance catheter and a micromanometer in 7 anesthetized mongrel dogs. We assessed preload by the end-diastolic volume, afterload by the effective arterial elastance, and left ventricular contractile properties by the slope of the end-systolic pressure-volume relationship. In addition, optimal ventricular arterial coupling (ratio of effective arterial elastance to slope of end-systolic pressure-volume relationship) and left ventricular work efficiency (ratio of external work to pressure-volume area) were calculated. RESULTS: The decrease in preload was much greater with LHB than venoarterial bypass. There were no significant differences in afterload and left ventricular contractility between venoarterial bypass and LHB. The ventricular arterial coupling during LHB was near 0.50 (0.69 +/- 0.16) in the "best heart" condition (effective arterial elastance = slope of end-systolic pressure-volume relationship/2), whereas the work efficiency during LHB was at maximum (0.73 +/- 0.12). CONCLUSIONS: We conclude that LHB has a more beneficial effect on left ventricular performance after cross-clamping of the descending thoracic aorta.

Animals↗
PubMed1998

Bilateral thoracoscopic minimally invasive direct coronary artery bypass grafting using internal thoracic arteries.

BACKGROUND: Single-vessel coronary artery bypass grafting of the left internal mammary artery (ITA) to the left anterior descending coronary artery using a minithoracotomy has been shown to produce excellent results with a very low mortality. However, this procedure cannot be used in patients with double- or triple-vessel disease. Our goal was to develop a minimally invasive direct coronary artery bypass grafting procedure without cardiopulmonary bypass for patients with multivessel disease. METHODS: Both ITAs were thoracoscopically harvested using video imaging. Limited bilateral anterior thoracotomies were performed in the fourth intercostal spaces, thus exposing the right coronary artery and the left anterior descending coronary artery. The right ITA-right coronary artery and ITA-left anterior descending coronary artery anastomoses were performed without cardiopulmonary bypass using 8-0 polypropylene sutures. RESULTS: This procedure was successfully performed in 3 patients. The patients were extubated in the operating room. Postoperative angiographic studies showed patent left ITA and right ITA grafts. CONCLUSIONS: Bilateral thoracoscopic minimally invasive direct coronary artery bypass grafting can be used to treat patients with a proximally diseased left anterior descending coronary artery and right coronary artery. Bilateral thoracoscopic ITA harvesting is a less invasive surgical technique that may become an option for the management of multivessel coronary artery disease.

Aged↗
PubMed1998

Clonidine reduces dopamine and increases GABA in the nucleus accumbens: an in vivo microdialysis study.

The effects of clonidine, an alpha2 adrenoceptor agonist, on extracellular concentrations of dopamine and gamma-aminobutyric acid (GABA) in the nucleus accumbens of rats were studied by using in vivo brain microdialysis. Clonidine (5 microg/kg i.v.) significantly decreased the brain microdialysate concentration of dopamine in the nucleus accumbens up to a maximum of 16% at its peak effect. This effect was inhibited by a dose of idazoxan (10 microg/kg i.v.), an alpha2-adrenoceptor antagonist. which itself did not affect the efflux of dopamine. A smaller dose of clonidine (1 microg/kg i.v.), which had no significant effect on dopamine efflux per se, decreased the dopamine efflux (21% reduction) when given together with an ineffective dose of midazolam (0.075 mg/kg i.v.), a benzodiazepine receptor agonist. The effect of clonidine (5 microg/kg i.v.) on mesolimbic dopamine efflux was abolished by bicuculline (1 mg/kg i.v.), a GABA(A) receptor antagonist, counteracted by beta-carboline-3-carboxylate ethyl ester (beta-CCE, 3 mg/kg i.p.), a benzodiazepine receptor inverse agonist, but not affected by flumazenil (6 microg/kg i.v.), a benzodiazepine receptor antagonist. Clonidine (5 microg/kg i.v.) increased the dialysate concentration of GABA in the nucleus accumbens up to a maximum of 250% at its peak effect, but not in the ventral tegmental area. It is hypothesized that GABA(A) binding sites in the nucleus accumbens form part of the sequence of events that is triggered by clonidine in an alpha2-adrenergic-specific manner and that ultimately results in a decreased release of dopamine in the nucleus accumbens.

Adrenergic alpha-Agonists↗
PubMed1998

Diagnostic value of technetium-99m methoxyisobutyl isonitrile (99mTc-MIBI) scintigraphy in detecting thyroid cancer metastases: a critical evaluation.

Technetium-99m methoxyisobutyl isonitrile (99mTc-MIBI) scintigraphy has recently been used in clinical application for detecting thyroid cancer metastases, its role being considered supplementary to serum thyroglobulin (Tg) measurements and radioactive iodine (131I) whole-body scans (WBS). The present retrospective study was designed to elucidate the role of 99mTc-MIBI scans in localizing metastatic lesions by assessing sensitivity and specificity of the scan results obtained in a group of 68 thyroidectomized thyroid cancer patients. Presence or absence of thyroid cancer was judged with other diagnostic modes including serum Tg measurements, 131I WBS, bone scans, chest x-rays, computed tomography (CT), ultrasonography, histopathology, and evolution of disease during follow-up. All scans were read on lesion basis for detecting neck, lung, and bone metastases and also on region basis, namely head-neck, chest, and abdomen-pelvis-extremities (ab-p-ex) areas. The sensitivity of detection was 94.4% (17/18) for neck, 78.4% (40/51) for lung, and 92.8% (64/69) for skeletal lesions. Positive predictive value (PPV) and negative predictive value (NPV) were 96.3% (26/27) and 97.7% (43/44) for head-neck; 94.7% (71/75) and 50.0% (12/24) for chest; 100.0% (25/25) and 93.1% (54/58) for ab-p-ex regions, respectively. For all scan sites taken together, PPV and NPV were 96.1% (122/127) and 86.5% (109/126), respectively. In conclusion, the present study reveals that 99mTc-MIBI can be proposed as a first-line diagnostic agent for the follow-up protocol of thyroid cancer patients, although the ability to detect small lung metastases is somewhat limited.

Adult↗