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Biomedical subjects

M Okada

Publications and source records attributed to M Okada.

At least 343 records · Page 19Linked to original sources
PubMed1999

Depth and intensity of equivalent current dipoles estimated through an inverse analysis of surface electromyograms using the image method.

The depth and intensity of equivalent current dipoles that can create the surface potentials of active motor units in human skeletal muscles are estimated through an inverse analysis of surface electromyographic (EMG) potentials in an attempt to measure detailed muscular activity non-invasively. The inverse analysis is conducted by repetition of forward analyses. In the study, the image method is used for forward analysis, because it is the simplest potential calculation method for electric currents in a semi-infinite volume conductor. Using this method, surface EMG potentials are calculated for current sources assumed to be located in a muscle. An inverse analysis is then carried out by searching for the depth and intensity of such current sources that would minimise the sum of squares difference between measured and calculated surface EMG potentials. The inverse analysis is applied to surface EMG potentials measured from the biceps brachii of three healthy subjects. As a result, the individual current sources are estimated to be 2.7 +/- 1.6 mm deep and 0.5 +/- 0.9 nAm in intensity, whereas the total current intensity for individual motor units is 2.4 +/- 2.9 nAm.

Adult↗
PubMed1999

Autoreactive T cells in murine lupus: origins and roles in autoantibody production.

The conventional paradigm to explain systemic lupus erythematosus (SLE) is that disease results from tissue deposition of pathogenic autoantibodies and immune complexes, secondary to activation of autoreactive B cells in the context of help from alphabeta T cells. Recent work in murine lupus has confirmed this notion and demonstrated that autoantigen-specific alphabeta T cells are absolutely required for full penetrance of disease, with such autoreactive alphabeta T cells, even in Fas-intact mice, likely arising from defects in peripheral tolerance. These studies have also revealed a network of regulation that also involves nonclassical pathogenic and downregulatory alphabeta and gammadelta T cells, suggesting that the lupus immune system involves more complex interactions than the conventional paradigm suggests.

Animals↗
PubMed1999

Right upper and middle sleeve bilobectomy with atypical pulmonary arterioplasty.

We report upon a case with hypoxia as a result of a primary lung cancer affecting the middle lobe leading to occlusion of the intermediate pulmonary artery and the upper pulmonary vein, which was successfully treated by combined right upper and middle sleeve bilobectomy and atypical pulmonary arterioplasty. Our case concerning atypical bronchoangioplastic procedures supported the validity of the technique for the lung cancer in a patient without pulmonary dysfunction.

Adenocarcinoma, Papillary↗
PubMed1999

Aortic valve replacement after retrosternal gastric tube reconstruction for esophageal cancer.

A 59-year-old man with a history of the thoraco-abdominal esophagus resection with retrosternal gastric tube reconstruction for esophageal cancer complicated by anastomosis leakage and purulent pericarditis was admitted for aortic regurgitation due to infective endocarditis. Floppy vegetation and worsening cardiac failure indicated aortic valve replacement. In a median sternotomy approach, the thickest adhesion between the cervical esophagus and posterior surface of the manubrium sternae was freed using an ultrasonic osteotome. Severe adhesions in the pericardium due to purulent pericarditis were found. Median sternotomy enabled minimal exposure of the aortic root, upper right atrium, and right superior pulmonary vein for instituting extracorporeal circulation and replacing the aortic valve. The patient's postoperative course was uneventful. For cardiac surgery in patients with a retrosternal gastric tube, left anterior or right thoracotomy may be considered to avoid gastric tube injury. Median sternotomy, however, is an alternative enabling safe heart exposure, and the ultrasonic osteotome was very useful in incising the sternum without injuring the cervical esophagus, which had no serosa.

Aortic Valve↗
PubMed1999

Valvular heart disease. A comparative study of results after primary operation, reoperation, and after multiple reoperation.

Reoperation for valvular heart disease has been associated with a higher operative mortality than primary operations, especially in patients who had multiple prior operations. We have analyzed the 226 consecutive patients who underwent valve replacement. These involved 163 primary operations, 52 first reoperation, and 11 second/third reoperations. Preoperative left ventricular dysfunction was more severe, and operation time and cardiopulmonary bypass time were significantly greater according to the number of operations, associated with a greater amount of intraoperative blood loss. The operative mortality after a second/third reoperation was 27.3%, which was significantly higher than that after primary operation (6.7%) (p < 0.05), and that after first reoperation (5.8%) (p < 0.05). Seven (64%) patients who underwent a second/third reoperation had poor preoperative left ventricular function (%FS < 25%), and 5 (71%) of these required postoperative mechanical supports, and 3 (60%) of the 5 patients died of low output syndrome. We have found that poor preoperative left ventricular function and the duration on cardiopulmonary bypass, but not the number of reoperation were correlated with operative mortality. Continued efforts should be directed to decrease the mortality for multiple reoperative valve surgery.

Adult↗
PubMed1999

Combined resection of the thoracic esophagus and thoracic descending aorta.

We conducted combined resection of the thoracic esophagus and thoracic descending aorta in 2 patients, one with advanced esophageal cancer with aortic invasion and the other aortoesophageal fistula caused by a false aortic aneurysm. Combined resection of esophageal tumor and adjacent involved organs was conducted in 14 patients with A3:T4 esophageal cancer but none survived 3 years and resecting tumor-invaded organs did not improve patient survival. One major problem of combined resection of the esophagus and aorta is contamination of the posterior mediastinum. In 1 patient, 2-stage surgery for the esophagus and in situ aortic replacement was conducted to reduce operative risk and avoiding infection of the prosthetic vascular graft. With thoracic descending aortic aneurysm adjacent to the esophagus on the increase, cardiovascular surgeons should prepared to undertake combined resection of both the aorta and esophagus.

Aged↗
PubMed1999

Intraabdominal nonvascular operations combined with abdominal aortic aneurysm repair.

The therapeutic approach to a patient who has an abdominal aortic aneurysm (AAA) and an intraabdominal nonvascular surgical disorder simultaneously remains controversial. To establish guidelines for the management of those patients, a retrospective review of patients who had concomitant AAA and intraabdominal nonvascular surgical disorders was undertaken. During the period January 1988 to December 1997 a series of 162 patients underwent surgical repairs of AAA in our hospital. Among them 16 patients (9.9%) had several kinds of intraabdominal nonvascular surgical disorders, and 13 underwent one-stage operation for both diseases. That is, cholelithiasis coexisted in five patients, inguinal hernia in four, gastric cancer in two, and retroperitoneal tumor and renal tumor in one each. All AAAs were the infrarenal type, and there were no inflammatory or ruptured aneurysms. In cases of cholelithiasis coexistent with AAA, aneurysmectomy was performed first. After tight closure of the retroperitoneum, cholecystectomy was done. In cases of cholelithiasis coexistent with AAA, aneurysmectomy was performed first. After tight closure of the retroperitoneum, cholecystectomy was done. In cases of inguinal hernia coexistent with AAA, the AAA was first replaced with a prosthetic vascular graft and a residual piece of the graft was used as a patch for hernioplasty. This procedure was similar to laparoscopic hernioplasty. In two cases of gastric cancer concomitant with AAA, the AAA was first replaced. Subtotal gastrectomy with D2 lymphatic dissection was done after tight closure of the retroperitoneum. A drain was inserted into the epiploic foramen to detect anastomotic leakage. A retroperitoneal tumor coexisting with AAA was dissected and resected en bloc with the aneurysmal wall because the tumor firmly adhered to the aneurysm. The abdominal aorta was then replaced with a prosthetic graft. In a case of renal tumor concomitant with AAA, nephrectomy was done first to perform a complete lymphatic dissection around the renal artery. Then AAA repair was performed with a conventional procedure. There were no fatal complications, such as pneumonitis, hemorrhage, anastomotic leakage, or graft infection. All 13 patients were discharged from our hospital and are currently free from recurrence of malignancy or hernia. In summary, properly selected one-stage operations for intraabdominal nonvascular surgical disorders and AAA may be safe and bring physical and economic benefit to the patient.

Aged↗
PubMed1999

Immunological diagnosis of Werner syndrome by down-regulated and truncated gene products.

Although immunological methods are widely used to diagnose various infectious diseases, they have rarely been employed to detect genetic diseases. In this study, we have established an immunoblot analysis system for the diagnosis of Werner syndrome (WS), a recessive genetic disorder causing premature aging and an enhanced risk of rare cancers. The method uses an immunoblot technique with specific monoclonal antibodies to WS gene product, and B-lymphoblastoid cell lines (LCLs) transformed by Epstein-Barr virus; these cell lines express an increased level of normal WS gene product DNA helicase. The method clearly distinguishes normal from patient LCLs containing any of the mutation types found so far in Japan, primarily because of the drastically reduced levels of mutated gene products, and secondarily because of the truncated product sizes. A comparison of this immunological diagnosis with the symptom-based clinical diagnosis has narrowed down the criteria of symptoms essential for WS diagnosis. This procedure is compatible with, and has some advantage over, the genetic method, because WS patients can be diagnosed without determining the mutated gene sequences. The method exemplified in WS may also be applied to detect some other genetic diseases.

Adult↗
PubMed1999

Perforation of the sigmoid colon with ischemic change due to polyarteritis nodosa.

A 60-year-old man who developed a perforation of the sigmoid colon with ischemic change due to polyarteritis nodosa is described. Histological examination of the resected colon led to the diagnosis of polyarteritis nodosa. Although the gastrointestinal tract is frequently involved with polyarteritis nodosa, it is extremely rare for polyarteritis nodosa to be accompanied by a perforation of the colon, particularly at the initial presentation.

Adrenal Cortex Hormones↗
PubMed1999

Evaluation of TMN classification for lung carcinoma with ipsilateral intrapulmonary metastasis.

BACKGROUND: Staging for lung cancer based on the TNM classification is an important predictive factor for prognosis. Recently, lung cancer with ipsilateral intrapulmonary metastasis (PM) was reclassified according to the revision of the TNM classification. To evaluate the prognostic importance of the new staging system for PM, we analyzed the postoperative survival of patients with non-small cell lung carcinoma. METHODS: Of 1,002 consecutive patients who underwent operation for primary lung cancer between June 1984 and December 1996, we reviewed the medical record of 889 patients who underwent complete resection for non-small cell lung cancer. RESULTS: We considered 89 patients (10.0%) to have synchronous ipsilateral PM. After reclassification to the former staging system revised in 1992, 5 patients were classified as stage I, 29 as stage IIIA, 48 as stage IIIB, and 7 as stage IV. In the new staging system revised in 1997, 48 patients were recategorized as stage IIIB, and 41 as stage IV. The 5-year survival of patients without PM (49.5%) was significantly better than that of patients with PM in primary-tumor lobe (29.6%, p = 0.002) or in nonprimary-tumor ipsilateral lobe (23.4%, p = 0.0002). Although the survival of patients with stage IV cancer without PM was significantly worse than that of patients with the new (1997) stage IV cancer with PM (p = 0.02), it was similar to that of patients with the former (1992) stage IV cancer with PM. The survival of PM patients with N0 or N1 disease was significantly better than that of PM patients with N2 or N3 disease (p = 0.001). Furthermore, in patients with the new (1997) stage IIIB cancer, the survival of N0 disease was better than that of N2 disease (p = 0.007). CONCLUSIONS: Inasmuch as the prognosis of non-small cell carcinoma in patients with PM strongly correlated with N factor rather than PM factor, N factor should be reflected in a staging designation. We therefore consider the new TNM classification for PM reclassified in 1997 to be less acceptable for surgical-pathologic staging than the revision in 1992.

Adult↗
PubMed1999

Transaortic video-assisted removal of a left ventricular thrombus.

A mobile and pedunculated left ventricular thrombus was developed after acute myocardial infarction in a 59-year-old man, and was successfully removed surgically through the aortic valve using a video-assisted thoracoscope. Transaortic video-assisted thoracoscopy greatly facilitated exposure of the interior of the left ventricle and preserved left ventricular function by avoiding ventriculotomy.

Endoscopy↗
PubMed1999

How should interlobar pleural invasion be classified? Prognosis of resected T3 non-small cell lung cancer.

BACKGROUND: The results of surgical treatment for non-small cell lung cancer with interlobar pleural involvement and direct invasion of the other lobe have seldom been documented. METHODS: Of 1,130 consecutive patients who were operated on for primary bronchogenic carcinoma between 1984 and 1997, we studied 132 patients who had complete resection of T3 non-small cell carcinoma. RESULTS: The structures involved were as follows: parietal pleura, 49 patients; chest wall, 45; interlobar pleura, 19; main bronchus within 2 cm of the carina, 11; mediastinal pleura, 6; and diaphragm, 1. Patients with N2 disease had a significantly worse survival than those with N0 (p = 0.0054) and N1 disease (p = 0.0165). The survival of patients with involvement of the interlobar pleura was significantly worse than that of patients with T1 (p = 0.0001) or T2 disease (p = 0.0484), and was similar to that of patients with T3 disease (p = 0.9821). CONCLUSIONS: In patients with T3 disease, mediastinal lymph node involvement influenced survival significantly. Patients with involvement of the interlobar pleura should be regarded as having T3 lesions.

Adult↗
PubMed1999

Increased prevalence of luteinizing hormone beta-subunit variant in patients with premature ovarian failure.

OBJECTIVE: To evaluate the significance of an LH variant with a mutant beta-subunit (Trp8 to Arg8 and Ile15 to Thr15) in gynecologic disease, including infertility. DESIGN: Clinical study. SETTING: Department of Obstetrics and Gynecology, Shimane Medical University Hospital, Izumo, Japan. PATIENT(S): Two hundred forty-five Japanese women with endocrine disorders and/or gynecologic disease and 153 healthy, nonpregnant, fertile Japanese women. INTERVENTION(S): A blood sample was collected. MAIN OUTCOME MEASURE(S): The ratio of LH values from the SPAC-S and Immulyze assays (LH ratio: SPAC-S LH/Immulyze LH) was used to determine variant (< or =0.5) or wild-type (>0.5) LH status according to a demonstrated relation between the ratio and the sequence of the LH beta-subunit gene. RESULT(S): The LH ratio was lower (0.80+/-0.31) in the 245 patients than in the controls (1.00+/-0.38), and the variant was more frequent in the patients (18.4%) than in the controls (8.5%). We found no difference in the frequency of the variant between infertile and fertile patients. The prevalence of infertility did not differ between patients with variant LH and patients with normal LH. Ovulatory disorders, hyperprolactinemia, premature ovarian failure, menstrual disorders, and luteal insufficiency were significantly more frequent in patients with the variant. CONCLUSION(S): Variant LH may contribute to female reproductive disorders, including infertility and premature ovarian failure.

Adolescent↗
PubMed1999

Extended sleeve lobectomy for lung cancer: the avoidance of pneumonectomy.

OBJECTIVE: We have tried atypical bronchoplasties in patients with noncompromised lung function with centrally located cancers to avoid pneumonectomy. We evaluated the efficacy of extended sleeve lobectomy in such patients. METHODS: Among 157 patients undergoing bronchoplasty for primary non-small cell lung carcinoma, 15 patients underwent extended sleeve lobectomy. RESULTS: According to the mode of reconstruction, the 15 patients were classified into 3 groups: (A) anastomosis between the right main and lower bronchi with resection of the upper and middle lobes (n = 6), (B) anastomosis between the left main and basal segmental bronchi with resection of the upper lobe and superior segment of the lower lobe (n = 4), and (C) anastomosis between the left main and upper division bronchi with resection of the lingular segment and lower lobe (n = 5). The tumors were completely resected in all patients. Pulmonary angioplasty was carried out in 8 patients. Bronchial reconstruction was successful in all patients. Pulmonary vein thrombosis resulting from overstretching of the inferior pulmonary vein occurred in 1 patient of group A and was relieved by completion pneumonectomy. There was neither operative mortality nor local recurrence. Although all patients with stage IIB disease and half of patients with stage IIIA disease were alive without recurrence (12-106 months), half of the patients with stage IIIA disease died of distant metastases within 1 year. CONCLUSIONS: We suggest that this extended sleeve lobectomy, which is technically demanding, should be considered in patients with centrally located lung cancer, because this lung-saving operation is safer than pneumonectomy and is equally curative.

Aged↗
PubMed1999

Prognosis of completely resected pN2 non-small cell lung carcinomas: What is the significant node that affects survival?

OBJECTIVE: We analyzed the effect of the station of mediastinal metastasis with regard to the location of the primary tumor on the prognosis in patients with non-small cell lung cancer. METHODS: Of 956 consecutive patients who underwent operation for primary lung carcinoma between 1986 and 1996, 760 patients (79.5%) were diagnosed as having non- small cell carcinoma and were subjected to complete removal of hilar and mediastinal lymph nodes together with the primary tumor. RESULTS: The status of lymph node involvement was N0 in 480 patients (63.2%), N1 in 139 patients (18.3%), and N2 in 141 patients (18.6%). The 5- and 10-year survival of patients with N2 disease were 26% and 17%, respectively. Neither cell type nor the extent of procedure was a significant survival determinant. Patients having involvement of subcarinal nodes from upper-lobe tumors had a significantly worse prognosis than those patients with metastases only to the upper mediastinal or aortic nodes (P =.003). Patients with nodal involvement of the upper mediastinum from lower-lobe tumors had a significantly worse survival than those patients with metastases limited to the lower mediastinum (P =.039). Furthermore, patients with involvement of the aortic nodes alone from left upper-lobe tumors had a significantly better survival than those patients with metastasis to the upper or lower mediastinum beyond the aortic region (P =.044). CONCLUSIONS: When mediastinal metastasis is limited to upper nodes from upper-lobe tumor, to lower nodes from lower-lobe tumor, or to aortic nodes from left upper-lobe tumor, acceptable survival could be expected after radical resection.

Adult↗
PubMed1999

Long-term evaluation of treatment for functional tricuspid regurgitation with regurgitant volume: characteristic differences based on primary cardiac lesion.

OBJECTIVES: The aim of this study was to characterize differences in the long-term effects of treatment for functional tricuspid regurgitation based on the primary cardiac lesion. METHODS: Ninety-six patients with valvular heart disease and 32 patients with atrial septal defects associated with tricuspid regurgitation were studied. The tricuspid annular diameter was associated with evidence of right heart failure. In valvular heart disease, a Kay annuloplasty was performed in 33 patients with a tricuspid annular diameter of >/=40 mm to 44 mm, a modified De Vega annuloplasty in 12 patients with a tricuspid annular diameter of >/=45 mm to 49 mm, and a modified De Vega annuloplasty, annuloplasty using a Carpentier ring, or tricuspid valve replacement in each of 4 patients with a tricuspid annular diameter of >/=50 mm. In atrial septal defects, a Kay annuloplasty was performed in 11 patients with a tricuspid annular diameter of >/=45 mm to 49 mm, and a modified De Vega annuloplasty was performed in 5 patients with a tricuspid annular diameter of >/=50 mm. A mean follow-up period was 79 months after operation. RESULTS: In the patients with a tricuspid annular diameter of <50 mm, the hemodynamic and clinical findings and tricuspid regurgitation remarkably improved. In the patients with valvular heart disease with a tricuspid annular diameter of >/=50 mm, however, the right heart parameters also showed improvement but less so when compared with those patients with a tricuspid annular diameter of <50 mm. In addition, 4 patients undergoing a modified De Vega annuloplasty have had a gradual increase in tricuspid regurgitation and clinical manifestations late after the operation. In contrast, all 5 patients with atrial septal defects with a tricuspid annular diameter of >/=50 mm have shown remarkable improvement, similar to those with a tricuspid annular diameter of <50 mm. Preoperative analyses revealed that the right heart function in atrial septal defects had not deteriorated to the same extent as in valvular heart disease. CONCLUSION: In the patients with a severely dilated tricuspid anulus (>/=50 mm), the postoperative change of tricuspid regurgitation differed between those patients with valvular heart disease and atrial septal defects.

Cardiac Output, Low↗