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Featured researches published by Masayasu Hamaji.


The Journal of Thoracic and Cardiovascular Surgery | 1997

Differentiated thyroid carcinoma with airway invasion: Indication for tracheal resection based on the extent of cancer invasion☆☆☆★

Toshirou Nishida; Kazuyasu Nakao; Masayasu Hamaji

OBJECTIVE Although aggressive approaches to locally invasive differentiated thyroid carcinoma are reported to improve the prognosis, few investigations have provided an indication for airway resection. The present study was undertaken to determine the best indication for airway resection for differentiated thyroid carcinoma invading the trachea. METHODS One hundred seventeen patients with differentiated thyroid carcinoma invading surrounding structures were retrospectively studied for local failures and prognosis and were divided into five groups mainly on the basis of macroscopic findings: Group 1 consisted of 40 patients who underwent tracheal resection for deep tracheal invasion; group 2 consisted of 14 patients with deep tracheal invasion and no airway resection; group 3 consisted of 13 patients with superficial tracheal invasion and no airway resection; group 4 comprised 48 patients with extrathyroidal invasion other than laryngotracheal structures; and group 5 consisted of two patients who underwent tracheal resection for superficial invasion. RESULTS Resectional management of the airway for patients with deep tracheal invasion decreased local recurrence and improved postoperative prognosis compared with nonresectional management for the tumor, or shaving off tumor from the trachea for patients with superficial invasion, did not increase postoperative local failures or mortality (group 3 vs groups 4, 5, and 1). CONCLUSION These results implied that differentiated thyroid carcinomas with superficially limited invasion could be treated successfully by nonresectional management of the trachea and that those with deep invasion should be treated by resection of the invaded trachea.


Annals of Surgery | 1997

Preservation of recurrent laryngeal nerve invaded by differentiated thyroid cancer.

Toshirou Nishida; Kazuyasu Nakao; Masayasu Hamaji; Wataru Kamiike; Kazushi Kurozumi; Hikaru Matsuda

OBJECTIVE This study was undertaken to determine whether the recurrent laryngeal nerve involved in differentiated thyroid carcinoma could be preserved. SUMMARY BACKGROUND DATA Few investigations have provided definitive results concerning preservation of the recurrent laryngeal nerve involved in thyroid cancer. Complete excision with resection of the recurrent laryngeal nerve reportedly did not improve survival over incomplete excision in differentiated thyroid carcinoma. METHODS A retrospective study was performed with the medical records of 50 patients with differentiated carcinoma and preoperative normal vocal cord function to investigate outcomes of recurrent laryngeal nerve preservation including local recurrence, prognosis, and postoperative vocal cord function. The recurrent laryngeal nerves on 1 or both sides were preserved in 23 patients (the preserved group), whereas the involved recurrent laryngeal nerve of the other 27 patients was resected (the resected group). RESULTS Backgrounds of patients were similar between the resected and preserved groups. The number of patients with recurrences in each group was similar, and incidence of local, regional, and distant metastatic recurrences were not different between the groups. Postoperative overall survival of the preserved group was similar to that of the resected group (p = 0.1208). More than 60% of patients or of nerve at risk in the preserved group restored normal vocal cord function within 6 months. Some functional vocal cord movement was recognized in 80% of patients or of nerve at risk. All patients in the resected group including patients with nerve anastomosis showed permanent paralysis of the ipsilateral vocal cord. CONCLUSIONS These results suggested that the recurrent laryngeal nerve, even if infiltrated by differentiated thyroid cancer, is worthwhile to preserve for maintenance of postoperative vocal cord function without affecting the incidence of local recurrence or prognosis.


Surgery | 1996

Overexpression of p53 protein and DNA content are important biologic prognostic factors for thyroid cancer

Toshirou Nishida; Kazuyasu Nakao; Masayasu Hamaji; Masaaki Nakahara; Masahiko Tsujimoto

BACKGROUND Many factors gave been reported to be of prognostic importance for thyroid cancer. Biologic aggressiveness may influence postoperative recurrences and the prognosis of thyroid cancer. Immunohistochemical staining for the p53 protein and DNA content are novel factors that suggest biologic aggressiveness. METHODS Retrospective study of the survival rate after operation of differentiated thyroid cancer was undertaken at Osaka Police Hospital. Age, gender operative method, extent of lymph node dissection, use of radioiodine, primary or recurrent tumor, tumor size and invasion, lymph node involvement, presence of distant metastases, DNA ploidy, percentage of S phase and G2M phase fractions, positive staining for the p53 protein, and histologic type and subtype were evaluated as possible prognostic factors by univariate and multivariate analyses of survival. RESULTS Positive staining for the p53 protein was related to postoperative local recurrence, and DNA ploidy was related to distant metastatic recurrence. Univariate analysis suggested that age, tumor size and invasion, lymph node involvement, presence of distant metastases, percentage of S phase fraction, histologic subtype, DNA ploidy, and positive staining for the p53 protein were significant prognostic factors. Multivariate analysis suggested that positive staining of the protein and DNA ploidy were independent prognostic factors for overall survival. CONCLUSIONS Both positive staining for the p53 protein and DNA ploidy, which suggest biologic aggressiveness, are independent prognostic factors for overall survival of patients with thyroid cancer, Examination of these biologic factors may provide new information regarding postoperative recurrences and the prognosis of thyroid cancer.


Brain Research | 1987

Projections of bombesin-like immunoreactive fibers from the rat stomach to the celiac ganglion revealed by a double-labeling technique

Masayasu Hamaji; Yoshinori Kawai; Yasunaru Kawashima; Masaya Tohyama

Gastrofugal bombesin (BOM)-like immunoreactive (BOMI) structures in the rat were studied by immunocytochemistry combined with retrograde labeling. Transection of the mesenteric nerve peripheral to the celiac ganglion resulted in the complete disappearance of BOMI nerve terminals, whereas transection of the splanchnic nerves did not alter the immunoreactivity. Injection of biotinylated wheat germ agglutinin into the celiac ganglion labeled several neurons in the myenteric ganglion of the stomach. Simultaneous staining with antiserum against BOM showed that some of them are BOMI-positive. These findings demonstrate that BOMI neurons in the myenteric ganglion of the rat stomach project to the celiac ganglion.


Journal of Chromatography B: Biomedical Sciences and Applications | 1979

Estimation of catecholamines in human plasma by ion-exchange chromatography coupled with fluorimetry

Masayasu Hamaji; Tokuichiro Seki

Estimation of catecholamines in human plasma was made by ion-exchange chromatography coupled with fluorimetry. Catecholamines in deproteinized plasma were adsorbed onto Amberlite CG-50 (pH 6.5, buffered with 0.4 M phosphate buffer) and selectively eluted by 0.66 M boric acid. The catecholamine fraction was separated further on a column of Amberlite IRC-50 which was coupled with a device for the automated performance of the trihydroxyindole method (epinephrine and norepinephrine) or the 4-aminobenzoic acid-oxidation method (dopamine). One sample could be analysed within 25 min with either method. The lower detection limits were 0.02 ng for epinephrine and dopamine, and 0.04 ng for norepinephrine. Plasma catecholamine contents of healthy adults at rest were epinephrine 0.07 +/- 0.01 ng/ml (n = 19), norepinephrine 0.27 +/- 0.03 ng/ml (n = 19) and dopamine 0.22 +/- 0.03 ng/ml (n = 26). The procedure of adsorption and elution of the plasma catecholamines by ion-exchange resin was simple, the simplicity contributing to constant recovery. The catecholamine fraction could be analysed without evaporation of the eluate. The analytical column could be used for the analysis of more than 1000 samples before excessive back-pressure developed. Our method of continuous measurement of plasma catecholamine fulfils clinical requirements.


World Journal of Surgery | 1997

Prognostic Significance of Proliferative Cell Nuclear Antigen in Carcinoma of the Extrahepatic Bile Duct

Toshirou Nishida; Kazuyasu Nakao; Masayasu Hamaji; Masaaki Nakahara; Masahiko Tsujimoto

AbstractBile duct cancers are still difficult to cure, and even if curatively resected locoregional recurrences are frequent. Biologic proliferative activity of the cancer may influence postoperative recurrence and the prognosis. A retrospective study was performed with the medical records of 44 consecutive patients who underwent surgery for histologically extrahepatic bile duct cancer (stage 3 or 4) at Osaka Police Hospital during the period 1980 to 1992. Univariate analysis suggested that the stage according to the UICC classification, curability, DNA ploidy, proliferating cell nuclear antigen (PCNA), S-phase and G2M-phase fractions, and histologic differentiation were significant prognostic factors. The Cox’s proportional hazard model indicated that PCNA and histologic differentiation were independent prognostic factors for crude and cause-specific survival. When PCNA was omitted from the analysis, DNA ploidy and histologic differentiation were independent prognostic factors for both crude and cause-specific survival. These results suggested that proliferative activity influenced the postoperative prognosis of extrahepatic bile duct cancer.


Canadian Journal of Anaesthesia-journal Canadien D Anesthesie | 1984

Anaesthetic management with morphine in phaeochromocytoma

Masayasu Hamaji; Norifumi Oka; Chikara Tashiro; Tokuichiro Seki; Masahiko Miyata; Yasunaru Kawashima

Morphine was used as the principal anaesthetic agent for five patients undergoing resection of phaeochromocytoma, and changes in plasma catecholamines were monitored. Phenoxygenzamine (0.5 mg.kg-1.day-1) was orally given one week before operation. After premedication with hyoscine (0.4 mg) and diazepam (20 mg) of meperidine (50 mg), anaesthesia was induced with an infusion of morphine (1 mg.kg-1) over 30 min and maintained with diazepam, nitrous oxide and oxygen. Pancuronium was used as the muscle relaxant. In three of the five patients, blood pressure transiently rose (ranging from 15 to 60 mg) following orolracheal intubation, but vasodilators were not required. In two of the three, plasma norepinephrine increases were 1.1 and 1.3 ng.ml-1. In the other two patients, whose blood pressure was stable, the change in plasma norepinephrine was 0.1 and 0.7ng.ml-1. After reaching a peak at the time of ligation of drainage vein from the tumour, plasma calecholmines rapidly decreased to the preoperative levels, but the blood pressure was well maintained in all cases. Ventricular arrhythmias did not occur despite the increased levels of endogenous catecholamines.These findings suggest that morphine can be used as an alternative anaesthetic agent during operation for phaeochromocytoma and that exaggerated pressor responses to morphine (when given slowly) seem not to occur in phaeochromocytoma.RésuméChez cinq malades, on a effectué une résection d’un phéochromocytome sous aneslhésie à la morphine en mesurant, durant l’intervention, les fluctuations des concentrations des catécholamines plasmatiques. Les malades ont été préparés â la phénoxybenzamine (0.5 mg.kg-1.jour-1) administrée par voie orale dans la semaine précédant l’intervention. A la suite d’une prémédication faite d’hyoscine (0.4 mg) et de diazépam (20 mg) ou de mépéridine (50 mg), on a induit l’anesthésiepar une infusion de sulfate de morphine (S mg.kg-1) sur une période de 30 minutes, complétée de diazépam, de proloxyde d’azote, d’oxygène et de bromure de pancuronium. Chez trois de ces cinq malades on a observé une augmentation transitoire de la pression artérielle de 15 à 60 mmHg au moment de l’intubation orotrachéale, mais cette augmentation n’a pas nécessité de vasodilatateurs. Chez deux de ces trois malades, on a observé une augmentation de la norépinéphrine plasmatique de 1.1 et 1.3 ng.ml-1respectivement. Chez les deux autres malades dont la pression artérielle est restée stable, les concentrations de norépinéphine plasmatique étaient respectivement de 0.1 et O7ng.ml-1. Une fois atteint le pic de concentration des catécholamines plasmatiques au moment de la ligature de la veine drainant la tumeur, les concentrations ont rapidement diminué au niveau préopératoire alors que la pression artérielle demeurait stable en tout temps. Aucune arythmie ventriculaire n’est apparue en dépit de ces variations des catécholamines endogènes. Ces constatations suggèrent que la morphine constitue un agent anesthésique acceptable pour la résection d’un phéochromocytome car les flambées hypertensives en réponse à la morphine administrée lentement ne semblent pus survenir en présence d’un phéochromocytome.


Brain Research | 1989

An electron microscopic study on VIP-, BOM- and CCK-like immunoreactive terminals in the celiac-superior mesenteric ganglion complex of the guinea pig.

Masayasu Hamaji; Yoshinori Kawai; Yasunaru Kawashima; Masaya Tohyama

The distribution and fine structure were studied of the following 3 peptide-containing fibers of enteric origin, vasoactive intestinal polypeptide (VIP), bombesin (BOM) and cholecystokinin (CCK)-like immunoreactive peptide in the celiac-superior mesenteric ganglion complex (CMG) of the guinea pig. These peptides, especially VIP, were distributed more densely on the mesenteric side than on the celiac side of the CMG, and their distribution shared a similar mosaic pattern. Immunoelectron microscopic analysis revealed that the fibers formed synaptic contacts with the proximal dendrites of the principal ganglion cells, however, the profiles of these synaptic junctions differed between fibers. Those containing VIP or CCK formed symmetrical synapses, while those containing BOM formed assymetrical ones. This suggests that there are some functional differences between these enterofugal fibers in the CMG.


Neuroscience Letters | 1989

Distribution of peptidergic terminals of enteric origin in the rat celiac ganglion

Masayasu Hamaji; Yoshinori Kawai; Yasunaru Kawashima; Masaya Tohyama

We examined the distribution of enterofugal nerve terminals of bombesin-, cholecystokinin- and vasoactive intestinal polypeptide-like immunoreactivity in the rat celiac-superior mesenteric ganglion complex. The majority of these nerve terminals were concentrated in the mesenteric side of the ganglion. The present findings suggest that some functional specialization occurs in the celiac ganglion of the rat.


Surgery Today | 1987

Segmental auto-transplantation of the pancreas

Masahiko Miyata; Kazuyasu Nakao; Masaaki Izukura; Masahiro Nakamura; Masayasu Hamaji; Hajime Hirose; Yasunaru Kawashima

A total pancreatectomy was performed in a 39-year-old man diabetic with diffuse calcification of the whole pancreas, a pseudocyst and intrapancreatic bile duct obstruction. The body of the excised pancreas was immediately transplanted into the left groin. The postoperative responses of plasma glucagon and insulin were not impaired compared with their preoperative responses. The patient was relieved of unremitting pain and is doing well six months after this operation.

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Masaaki Nakahara

Wakayama Medical University

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