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Biomedical subjects

T Nagashima

Publications and source records attributed to T Nagashima.

At least 91 records · Page 5Linked to original sources
PubMed1999

Thermoregulatory responses of the inbred heat-tolerant FOK rat to cold.

The responses of inbred heat-tolerant FOK rats to cold were compared with those of Wistar King A/H (WKAH) and Std:Wistar (WSTR) strains. The fall of colonic temperature during cold exposure was unexpectedly smaller in FOK than in other groups, but the onset of shivering was delayed in FOK. Norepinephrine (NE)-induced in vivo oxygen consumption and the mitochondrial uncoupling protein 1 level of brown adipose tissue (BAT) were not different among the groups, but the cold-induced increases in in vivo oxygen consumption as well as plasma glycerol and free fatty acids were higher in FOK than in other groups. In vitro NE-induced oxygen consumption of BAT was less in FOK than WSTR, but not WKAH. The magnitude of the NE-induced increase in blood flow through BAT was higher in FOK than in other groups. These results suggest that FOK paradoxically have a high capacity for nonshivering thermogenesis in spite of their high capacity for heat tolerance, probably due to an increased lipid utilization and improved circulation of BAT.

Adaptation, Physiological↗
PubMed1999

Pituitary somatotroph adenoma producing growth hormone (GH)-releasing hormone (GHRH) with an elevated plasma GHRH concentration: a model case for autocrine and paracrine regulation of GH secretion by GHRH.

An acromegalic patient with a pituitary somatotroph adenoma associated with an extremely elevated plasma GHRH concentration is presented. The preoperatively high concentration of plasma GHRH returned to the normal level after successful removal of the adenoma. GHRH production and GHRH gene expression were confirmed in the adenoma by studies including immunohistochemistry and in situ hybridization. Expression of GHRH receptor messenger ribonucleic acid was verified by in situ hybridization. Immunohistochemical double staining for GH and GHRH revealed their colocalization in single adenoma cells. These findings confirmed the autocrine or paracrine regulation of GH production by endogenous GHRH from the adenoma cells. GHRH synthesis in the pituitary gland has recently been demonstrated, however, there have been no previous reports of a GHRH-producing pituitary somatotroph adenoma associated with an elevated plasma GHRH concentration. The existence of this GHRH-producing adenoma suggests a possible role of locally generated GHRH in the progression of somatotroph adenomas, i.e. the monoclonally established somatotroph adenomas develop further under the influence of locally produced GHRH. The demonstration of GHRH production by this somatotroph adenoma is of importance in clarifying the autocrine or paracrine regulation of GH production and the progression of human somatotroph adenomas.

Acromegaly↗
PubMed1999

Craniocervical junction synovial cyst associated with atlanto-axial dislocation--case report.

A 51-year-old female presented with a rare case of synovial cyst at the cruciate ligament of the odontoid process associated with atlanto-axial dislocation, manifesting as a history of headache and numbness in her left extremities for 5 months, and progressive motor weakness of her left leg. Neuroimaging studies revealed a small cystic lesion behind the dens, which severely compressed the upper cervical cord, and atlanto-axial dislocation. The cyst was successfully removed via the transcondylar approach. C-1 laminectomy and foramen magnum decompression were also performed. Posterior craniocervical fusion was carried out to stabilize the atlanto-axial dislocation. The cyst contained mucinous material. Histological examination detected synovial cells lining the fibrocartilaginous capsule. Synovial cysts of this region do not have typical symptoms or characteristic radiographic features. Careful preoperative evaluation of the symptoms and a less invasive strategy for removal of the cyst are recommended.

Atlanto-Axial Joint↗
PubMed1999

Effect of cerebrospinal fluid shunting on experimental syringomyelia: magnetic resonance imaging and histological findings.

The histological changes associated with syringomyelia after reduction of the syrinx size were investigated after cerebrospinal fluid shunting in experimental syringomyelia in the rabbit. Five weeks after syringomyelia was induced by the injection of kaolin into the cisterna magna in Japanese white rabbits, ventriculosubgaleal shunting or syringoepidural shunting were performed. After 1 week magnetic resonance (MR) imaging and histological examination were then carried out. Five of 11 shunted animals showed postoperative reduction of syrinx size on MR imaging. Grossly, some specimens showed cavity collapse and parenchymal healing, and others showed a small residual syrinx in the dorsal horn. The most dramatic histological changes occurred in the gray matter. Specimens with syrinx collapse showed rarefaction and tearing of the gray matter, with mild glial reaction. The edematous gray matter showed both degeneration and regeneration, with neuronal processes surrounded by edema fluid. Reactive astrocytes were observed mainly at the margin of the residual syrinx. Some astrocytic processes invested the extraaxonal space and gray matter lacked supportive tissue. Greater reduction of the syrinx after shunting operation was correlated with more regeneration and less degeneration, and the white matter was edematous and histological changes were milder. Syrinx shrinkage occurred after shunting in this experimental model of syringomyelia. The selective vulnerability of gray matter even after shunting may explain discrepancies between imaging findings and clinical features in this disease. The study supports the potential benefit from early treatment, considering the associated morphological findings of regeneration.

Animals↗
PubMed1999

[A case of primitive neuroectodermal tumor of the kidney].

A primitive neuroectodermal tumor (PNET) is a solid tumor originating from the neural crest. This tumor is known to occur in the central nervous system and soft tissue, but recently determined to also invade the kidney. Although primary renal PNET is very rare, we encountered a case of primary renal PNET with multiple lung metastasis. This case was a 35-year-old man with a chief complaint of macroscopic hematuria, which he noticed in January 1996. He was hospitalized because of right renal tumor detected with ultrasonography. On CT scan, a low-density solid tumor with a maximum diameter of 8 cm was visualized in the right kidney. Low-signal and high-signal tumorous lesions were demonstrated in the same region on T 1-weighted and T 2-weighted MR images, respectively. Then right radical nephrectomy was performed on Feb. 5, 1996. On histopathological observation, the tumor was composed of small tumor cells with solid growth. Immunohistochemical staining revealed that the tumor was positive for CD 99. Thus our final diagnosis was primary right renal PNET. Although 2 metastatic lesions with a diameter of about 1 cm were observed in the right lower lung before the time of surgery, pulmonary metastatic lesions markedly increased in number 3 months after surgery. Thus we initiated CAP chemotherapy with cyclophosphamide, doxorubicin, and CDDP. After 3 cycles, pulmonary metastatic lesions disappeared at CT scan, indicating complete remission. However, a tumor with a maximum diameter of about 10 cm recurred in the retroperitoneum 7 months after complete remission. Although 2 cycles of CAV/PE therapy with cyclophosphamide, doxorubicin, vincristine, CDDP, and VP-16 were performed following resection of the retroperitoneal tumor, he showed no response and decreased 24 months after surgery.

Adult↗
PubMed1999

[Surgical technique and long-term follow-up of laminoplasty using titanium miniplates].

Problems concerning a spinal deformity due to simple laminectomy and the usefulness of laminoplasty are often reported recently. In our hospital, laminoplasty with titanium miniplates for spinal operations has been used in all cases since 1992. We started to use this method after we encountered several cases of post-operative spinal deformity following multiple-level laminectomy. We reviewed two different subgroups of patients. Group A consisted of 38 cases who were operated on using simple laminectomy. Group B consisted of 32 cases who were operated on using laminoplasty with titanium miniplates. Postoperative spinal deformity occurred in 5 patients of Group A (13%), and in none of Group B (0%). In particular, postoperative spinal deformity occurred in one child case of Group A (33%), and in none of Group B (0%). Laminoplasty is a very simple and efficient technique, and advantages are the presentation of stability of the posterior column and curvature of the laminae, as well as protection of the spinal cord. Compatibility with magnetic resonance imaging (MRI) is another advantage of titanium miniplates, because long follow-up using MRI is always necessary in these cases. In conclusion, laminoplasty with titanium miniplates for spinal operations are a very useful and safe technique.

Aged↗
PubMed1999

[Spontaneous epidural hematoma after open heart surgery: case report].

Acute epidural hematoma not associated with head injury is rarely encountered and is known as spontaneous epidural hematoma. To our knowledge, only five cases with epidural hematoma after open-heart surgery have been published. Pathogenesis and preventive measures have not yet been determined. We report a case of such spontaneous epidural hematoma and consider the possible pathogenesis. A 12-year-old female received a radical operation for severe subaortic stenosis. The intraoperative course was uneventful except for massive hemorrhage which was adequately controlled. Postoperatively, she was moved to the CCU still not having aroused from anesthesia. Eleven hours later, it was found that her pupils were fixed and dilated. CT scan demonstrated a huge bifrontal epidural hematoma with disappearance of the basal cistern. Even though immediate emergency evacuation was performed, the patient died of acute brain swelling four days after the operation.

Anticoagulants↗
PubMed1998

Combined chemotherapy and radiation therapy for central nervous system germ cell tumors: preliminary results of a Phase II study of the Japanese Pediatric Brain Tumor Study Group.

The authors conducted a multiinstitutional phase II study to establish a postsurgical combined chemotherapy and radiation therapy regimen for patients with primary germ cell tumors of the brain. After surgical debulking of the tumor and histological verification, patients were divided into three therapeutic groups: good prognosis, intermediate prognosis, and poor prognosis. Patients received two kinds of chemotherapy (three courses) prior to receiving radiation therapy: carboplatin-etoposide combination ([CARB-VP]: carboplatin 450 mg/m(2) on Day 1, etoposide 150 mg/m(2) on Days 1-3) or ifosphamide-cisplatin-etoposide combination ([ICE]: ifosphamide 900 mg/m(2), cisplatin 20 mg/m(2), and etoposide 60 mg/m(2) on Days 1-5). Patients in the good prognosis group (those with germinomas) were treated with CARB-VP followed by local radiation therapy (24 Gy). Patients in the intermediate prognosis group received CARB-VP followed by local radiation therapy (50 Gy); they received five additional chemotherapy treatments. Patients in the poor prognosis group received ICE followed by whole craniospinal radiation therapy; they also received five additional chemotherapy treatments. Eighty-two patients were evaluated. For the 56 patients with germinomas, a 93% rate of complete remission after treatment was achieved. The remission rate was 76% for 21 patients in the intermediate prognosis group, and no recurrence was detected during a median follow-up period of 2.6 years. In the group of five patients with poor prognosis, the disease in three patients progressed during chemotherapy or radiation therapy and they died within 6 months. There were no serious complications in the surviving patients. The authors found their treatment protocols to be currently effective for patients with germinomas and those with an intermediate prognosis.

Journal Article↗
PubMed1998

Predicting the prognoses of breast carcinoma patients with positron emission tomography using 2-deoxy-2-fluoro[18F]-D-glucose.

BACKGROUND: Positron emission tomography (PET) with 2-deoxy-2-fluoro[18F]-D-glucose (FDG) can provide quantitative information about tumor glucose metabolism. The prognostic value of this technique was evaluated for breast carcinoma patients. METHODS: FDG PET was performed on 70 patients with primary breast carcinoma, and the differential absorption ratio (DAR) was calculated as an index of FDG uptake. Overall and relapse free survival curves were created by the Kaplan-Meier method, and differences between the curves were analyzed with the log rank test. For multivariate analysis, the Cox proportional hazards regression model was used. RESULTS: The mean DAR was 2.61+/-1.61 standard deviation (range, 0.65-9.39). According to the grade of DAR, patients were then classified into high DAR (> or =3.0) and low DAR (<3.0) groups. The high DAR group had significantly worse prognoses for both overall and relapse free survival (P < 0.0005 and P < 0.0001, respectively). In multivariate analysis, DAR was an independent predictor of the relapse free survival of breast carcinoma patients (P=0.0377). CONCLUSIONS: DAR, as determined by FDG PET, may be useful as a prognostic indicator for patients with primary breast carcinoma.

Adult↗
PubMed1998

Morphometry in the cytologic evaluation of thyroid follicular lesions.

BACKGROUND: The current study was undertaken to evaluate the quantitative estimation of cytologic features on aspirated smears for the preoperative differential diagnosis of follicular lesions of the thyroid. METHODS: The subjects were 60 patients with follicular lesions of the thyroid (including 20 follicular carcinomas, 15 follicular adenomas, and 25 adenomatous goiters) whose histopathologic explorations were conducted fully postoperatively. Using a microscope connected to a computerized video system, the mean nuclear area, the mean nuclear perimeter, the circular rate, the largest to the smallest dimension ratio (LS ratio) of the nuclei, and the coefficient of variation of the nuclear area (NACV) were measured and analyzed. RESULTS: Among the quantitative morphometric parameters of nuclei, the circular rate was significantly higher in the group with adenomatous goiters than those with follicular carcinomas (P < 0.00001) and adenomas (P < 0.005). The group with follicular carcinomas had a higher LS ratio than the group with adenomatous goiters (P < 0.0005). The NACV value increased as the malignant potential of the lesion increased and showed significant differences between the groups. When a NACV of 21.5% was chosen as the cutoff point, the incidence of malignancy was significantly higher in patients with high NACV values than in those with low NACV values (P < 0.00001). Using this borderline value, it was possible to distinguish malignant from benign diseases with a sensitivity of 85.0%, a specificity of 82.5%, and an accuracy of 83.3%. CONCLUSIONS: Preoperative quantitative estimations of cytologic nuclear features are useful for the preoperative differential diagnosis of follicular lesions of the thyroid.

Adenocarcinoma, Follicular↗
PubMed1998

Hirschsprung's disease in an adult patient with familial occurrence: report of a case.

Hirschsprung's disease is almost always associated with newborns or infants; however, we report herein the unusual case of a 46-year-old woman in whom the symptoms of Hirschsprung's disease emerged late in adult life. The involved rectosigmoid region was successfully removed by performing Duhamel's operation with a diverting colostomy. After the colostomy was closed, she regained normal defecatory function. She had one male child affected by Hirschsprung's disease of the total colon type who was operated on as a 12-month-old baby. The genetic predisposition of Hirschsprung's disease has been reported, but its mode of inheritance has not yet been clarified. Moreover, most papers on the familial occurrence of this disease have reported that siblings were affected. Our patient was unique for the definite occurrence of the disease in successive generations. The features of Hirschsprung's disease in adults and the familial occurrence are discussed with a review of the literature.

Anastomosis, Surgical↗
PubMed1998

Combined transpetrosal and fronto-orbito-zygomatic approach to a giant skull based meningioma: a case report.

BACKGROUND: Recently, various surgical approaches to skull base lesions have been developed. Skillful use of the combination of two standard approaches make possible the removal of large brain lesions, which conventionally had been considered inoperative. In this study, we present a case of a giant meningioma located in the cerebellopontine angle and middle cranial fossa. A near total resection was achieved using a combined transpetrosal and fronto-orbito-zygomatic approach. CASE REPORT: A 15-year-old boy presented with a meningioma that caused a left hearing loss, dysarthria, and cerebellar ataxia. Preoperative magnetic resonance imaging revealed a giant meningioma located in the right cerebellopontine angle, middle fossa, and cavernous sinus. The patient underwent a near total resection of the tumor through a combined transpetrosal and fronto-orbito-zygomatic approach. He experienced a marked improvement postoperatively and entered high school the following year. CONCLUSIONS: An approach from several angles was necessary for the giant skull based tumor presented here. A combination approach was selected for obtaining a wide operative field with minimal brain compression during resection of neoplasm. According to the individual features of each case, selection of the operative approach, decisions regarding the extent of excision, and postoperative treatment regimens should be adequately planned in the preoperative period.

Adolescent↗
PubMed1998

Cerebral ischemia affects glucose transporter kinetics across rat brain microvascular endothelium: quantitative analysis by an in situ brain perfusion method.

BACKGROUND: It has been reported that cerebral ischemia induces a dissociation between cerebral blood flow and blood-brain barrier glucose transport, but mechanisms of the dissociation are not yet clearly understood. Recent immunohistochemical studies reveal discrepancies of the results between physiologic and immunochemical studies. The purpose of this study was to quantify changes of the blood-brain barrier glucose transporter kinetics following cerebral ischemia by an in situ brain perfusion technique. METHODS: Fifty-six adult male Sprague-Dawley rats were divided into control and ischemia groups, and four-vessel occlusion was done as an ischemic insult. To obtain regional capillary permeability surface area products of glucose and regional perfusion fluid flow rates, the perfusion fluid (HCO3-buffered saline) was dually labeled with [14C]-2-Deoxyglucose and [3H]-Diazepam, and the brain was perfused at a constant rate via the external carotid artery. After sampling tissues from three regions (frontal, frontoparietal lobe, and caudoputamen), dual scintillation counting was performed. From the results, we determined kinetic parameters, including Vmax, Km, and Kd as described in the Michaelis-Menten equation, by weighted nonlinear least squares method. RESULTS: In the ischemia group, the affinity (1/Km) and the maximum glucose transport rate (Vmax) decreased significantly. CONCLUSIONS: The results suggest that severe cerebral ischemia down-regulates the blood-brain barrier glucose transporter kinetics, and the discrepancies between physiologic and immunohistochemical studies may be derived from redistribution of transporters, some deformation of transporters, production of some inhibitors, recruitment of capillaries with different types of transporters, and/or the effect of surrounding glial reaction.

Animals↗
PubMed1998

An improved ultrastructural double-staining method for rat growth hormone and its mRNA using LR White resin: a technical note.

An improved new method for the simultaneous visualization of mRNA and encoded protein in LR White resin-embedded specimens is described. This pre-embedding electron microscopical in situ hybridization (procedure) localized rat growth hormone mRNA specifically as high electron-density products on the polysomes of the rough endoplasmic reticulum. A subsequent post-embedding immunoreaction, using protein A colloidal gold particles, identified growth hormone as gold particles both in the cisternae of the rough endoplasmic reticulum and on the secretory granules. In our previous report, we used Epon resin for tissue embedment, which required an etching process using hydrogen peroxide or sodium periodate for immunoreactivity retrieval. In general, osmification and embedment in Epon resin are reported to decrease the immunoreactivity of the targeted protein, and the etching process using hydrogen peroxide or sodium periodate results in deosmification and shades off the signals of mRNA. To resolve these problems, we have recently used LR White resin for tissue embedment. In LR White resin-embedded tissues, retrieval of immunoreactivity using hydrogen peroxide or sodium periodate is not required, and, therefore, the gradation of the signals of mRNA can be avoided.

Acrylic Resins↗