Biomedical subjects

T Aiba

Publications and source records attributed to T Aiba.

At least 55 records · Page 3Linked to original sources

PubMed1994

Creutzfeldt-Jakob disease transmitted by a cadaveric dura mater graft.

We report a case of Creutzfeldt-Jakob disease developing in a 31-year-old woman 56 months after she received a cadaveric dura mater graft after the removal of a giant pituitary adenoma. Creutzfeldt-Jakob disease was confirmed by a brain autopsy and the existence of an abnormal isoform of prion protein, verified by both immunohistochemical and Western blot analysis. Moreover, prion protein gene analysis was shown in this case to possess a wild-type genotype. The characteristics of Creutzfeldt-Jakob disease after a cadaveric dura mater graft are reviewed and discussed.

Adenoma↗

PubMed1994

Kinetic analysis of neuromuscular blockade. I. Relationship between twitch depression and stimulation frequency after d-tubocurarine administration.

The degree of twitch depression induced by nondepolarizing neuromuscular blocking drugs is known to be dependent on the stimulation frequency employed. Train-of-four (TOF) stimulations with different frequencies (0.67, 1.33 and 2.0 Hz) were delivered to a sciatic nerve of a rat and series of four twitch heights of a tibialis anterior muscle were measured after d-tubocurarine (d-TC) administration. With a decrease of stimulus interval, twitch heights were intensely depressed. We hypothesized that the oservations are due to the changes of released amount of neuromuscular transmitter, acetylcholine, dependent on stimulus interval, and a pharmacokinetic/pharmacodynamic model based on the hypothesis was proposed. The model allowed simultaneous fitting of the twitch height depression after d-TC administration. It also could give a rationale to the fact that TOF stimulation at 2.0 Hz is a more sensitive monitoring method of neuromuscular function than single twitch stimulation (0.1-0.2 Hz).

Acetylcholine↗

PubMed1994

Kinetic analysis of neuromuscular blockade. II. Train-of-four fade induced by d-tubocurarine and alpha-bungarotoxin.

The degree of train-of-four (TOF) fade, i.e., the reduction of the fourth to the first twitch height in a train, induced by d-tubocurarine (d-TC) and alpha-bungarotoxin (alpha-BX) was investigated. The fade induced by d-TC was pronounced in comparison with that by alpha-BX, and the difference was analyzed using a kinetic model. Based on the assumptions: (1) Acetylcholine (ACh) binds to the nicotinic receptor and evokes twitch response. (2) The amount of released ACh is dependent on stimulus interval. (3) d-TC interacts competitively with the receptor. (4) alpha-BX interacts irreversibly with the receptor. It was suggested that the fade by d-TC and alpha-BX can be explained by the difference of the receptor occupancy by ACh which was caused by different interaction mechanisms of the two muscle relaxants with receptors.

Acetylcholine↗

PubMed1994

Calcified intracranial metastatic tumor mimicking meningioma--case report.

A 60-year-old female presented with mild cerebellar dysfunction due to a calcified tumor attached to the undersurface of the tentorium cerebelli demonstrated by cranial computed tomography, and a lung mass on a chest x-ray film. The calcified nature and location made preoperative differentiation between metastatic brain tumor and meningioma difficult. Operation subsequently revealed that the brain tumor was a metastasis from lung adenocarcinoma. Metastatic brain tumors can be calcified, and should be considered in the differential diagnosis of calcified intracranial lesions.

Adenocarcinoma↗

PubMed1994

Preservation of hearing after surgery for acoustic schwannomas: correlation between cochlear nerve function and operative findings.

The results of surgery in 66 patients with acoustic schwannoma in whom total tumor removal was accomplished are reviewed in terms of the relationships among tumor size, preoperative hearing level, operative findings (including the shape and location of the cochlear nerve at the tumor surface), and the extent of postoperative hearing preservation. Both tumor size and the preoperative hearing level were correlated with the shape of the cochlear nerve, which more frequently formed a solid bundle when the tumor was small or the preoperative hearing was excellent. Hearing was retained postoperatively only in cases in which the nerve formed a solid bundle and could be differentiated and separated from the tumor capsule without difficulty. These findings suggest that tumor size and preoperative hearing level, which have been reported to be the main prognostic factors of postoperative hearing preservation, may influence the results of surgery for acoustic schwannoma through the shape of the cochlear nerve.

Cochlear Nerve↗

PubMed1994

Intracytoplasmic granulofilamentous inclusion bodies in a meningioma. Immunohistochemical and ultrastructural studies.

A case of cerebellar tentorial meningioma, with abundant, large, eosinophilic intracytoplasmic inclusions, was studied immunohistochemically and ultrastructurally. These intracellular inclusions were periodic acid-Schiff negative and ultrastructurally appeared as a condensation or aggregation of numerous intracytoplasmic intermediate filaments. These inclusions were not related to microvillus-lined ductules, indicating that these inclusions were distinct from pseudopsammoma bodies. In addition, these inclusions were intensely immunopositive for vimentin, whereas staining for glial fibrillary acidic protein, epithelial membrane antigen, cytokeratin, neurofilament, desmin, actin, or type IV collagen was negative. To our knowledge, this is the second reported case of meningioma with such unusual inclusions, but the first one to demonstrate that the intracytoplasmic intermediate filaments and their related inclusions were mainly composed of vimentin.

Cytoplasm↗

PubMed1993

Atypical manifestations of tuberculous meningitis.

We describe 2 patients with tuberculous meningitis who exhibited unusual changes of their cerebrospinal fluid (CSF) which led to confusion in their management. Patient 1 was a 25-year-old man who displayed persistent polymorphonuclear dominant pleocytosis in his CSF. Autopsy revealed marked hypoplasia of the thymus and T cell areas of the lymph nodes, consistent with the Nezelof syndrome, as well as disseminated tuberculosis. Patient 2 was a 39-year-old woman who demonstrated, during appropriate antituberculous chemotherapy, an atypical exacerbation consisting of prolonged fever, polymorphonuclear dominant pleocytosis in her CSF and multiple cerebral infarcts. The neurological abnormalities in the patient underwent marked improvement following oral prednisolone therapy.

Adult↗

PubMed1993

Endocrine and morphological study of a clinically silent somatotroph adenoma of the human pituitary.

Silent somatotroph adenomas are defined as tumors showing morphological features consistent with GH production, but no clinical evidence of GH excess. We report here the case of a 46-yr-old woman with a large pituitary macroadenoma, slightly elevated serum GH levels, high serum insulin-like growth factor-I levels, and abnormal GH dynamics, but no acromegaly. The endocrinological abnormalities receded after transphenoidal surgery despite tumor persistence, as shown by neuroimaging. The reverse hemolytic plaque assay, performed for the first time in a silent GH cell adenoma, demonstrated that the number of GH cells releasing GH and the amount of GH discharged from individual cells were less than those in clinically functioning somatotroph adenomas. Thus, it is conceivable that this tumor secreted only small quantities of GH and for only short periods, providing an explanation for the lack of acromegaly. It appears that silent somatotroph adenomas do not represent a distinct entity. It is more likely that there is a continuous spectrum from clinically functioning, sparsely granulated somatotroph adenomas with high serum GH levels to silent somatotroph adenomas with normal serum GH levels. The cause of the lack of GH oversecretion in silent GH cell adenomas has yet to be elucidated.

Adenoma↗

PubMed1993

Growth hormone-producing pituitary adenomas: correlations between clinical characteristics and morphology.

In this study, we compared the clinical and endocrinological characteristics, neuroimaging findings, surgical outcome, and conventional histological findings (including immunohistochemistry) with the electron microscopic appearance of 31 growth hormone (GH)-producing adenomas. By electron microscopy, these 31 tumors were divided into 23 densely granulated somatotroph adenomas (DG adenomas) and 8 sparsely granulated somatotroph adenomas (SG adenomas). SG adenomas more frequently affected younger women, but no significant correlation was found between the adenoma type and the characteristic signs and symptoms of acromegaly, the incidence of diabetes mellitus or hypertension, or the basal serum GH and insulin-like growth factor I levels. A distinct response of GH to thyrotropin-releasing hormone, bromocriptine, or GH-releasing hormone was significantly more common in patients with DG adenomas than in those with SG adenomas, whereas the incidence of a response to gonadotropin-releasing hormone or oral glucose was not significantly different between the two groups. An analysis of neuroimaging findings and surgical results indicated that SG adenomas were more likely to be macroadenomas with suprasellar extension or invasive tumors and had a lower surgical cure rate. However, postoperative radiotherapy seemed to be similarly effective in both types of adenoma to prevent a tumor recurrence and to reduce postoperative GH basal level in serum. Light microscopy showed that DG adenomas were mainly acidophilic and were immunopositive not only for GH but also for prolactin (43%), the beta subunit of thyroid-stimulating hormone (26%), and the alpha subunit of glycoprotein hormone (87%), whereas SG adenomas were almost all chromophobic and only revealed immunopositivity for GH.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenoma↗

PubMed1993

Nerve growth factor (NGF) and its receptor in rat olfactory epithelium.

Nerve Growth Factor (NGF) is a bioactive protein that plays an important role in the genesis, differentiation, growth, maintenance and aging of the central and peripheral nervous systems. The purpose of this study was to explore the significance of NGF in the turnover, regeneration and maintenance of the olfactory epithelium. We tried to detect NGF and NGF-receptor in the olfactory epithelium of young and mature rats with an immunohistochemical technique. Immunoreactivity to NGF and NGF-receptor was detected in all specimens of olfactory epithelium. Immunoreactivity to NGF was positive in the olfactory nerve cells, especially in the cytoplasm and dendrites, in the basal cell layer, and on fibers piercing the olfactory epithelium. Immunoreactivity to NGF-receptor was positive in the basal cell layer and on fibers piercing the olfactory epithelium. These results suggest that NGF plays a role in the maintenance of olfactory nerve cells, and in the differentiation from the basal cell to the mature olfactory nerve cell, in both the young and the mature rat. In addition, the differences in the density of immunoreactive cells between different parts of the olfactory epithelium support the concept of an active and a quiescent zone in olfactory epithelium turnover.

Aging↗

PubMed1993

Cerebellopontine angle medulloblastoma: case report and literature review.

The occurrence of cerebellopontine angle (CPA) medulloblastoma is a rare phenomenon. We report such a case in a 19-year-old girl who had 6th and 8th cranial nerve palsies as well as cerebellar dysfunction. The tumour arose from the left flocculus or adjacent cerebellar hemisphere and projected into the CPA. She was treated by subtotal removal of the tumour, followed by entire neuroaxis irradiation and immunochemotherapy. The clinical characteristics and pathogenesis of CPA medulloblastoma are reviewed and discussed.

Adult↗

PubMed1993

The impact of an increased number of the foreign inpatients to the rural public hospital of Japan.

A rapid inflow of the foreign laborers into Japan has become obvious since a couple years ago when a serious shortage of labor had to be repaired urgently. A sudden increased number of the foreign inpatients had resulted in the problems for a rural public hospital, which sought sound solutions for them. Difficulty in communication with those whose mother tongue was not English, was one of them. Though it was not serious yet, a payment for medical care they had received, had been a burden both for them and for the hospital. This was because there was not private health insurance available for them. Asymptomatic infectious disease such as pulmonary tuberculosis was another problem, for which a routine physical examination would be required before or immediately after their entry into Japan.

Catchment Area, Health↗

PubMed1993

Role of P-glycoprotein in renal tubular secretion of digoxin in the isolated perfused rat kidney.

The mechanism for renal tubular secretion of digoxin as well as its interaction with quinidine or verapamil were investigated using the isolated perfused rat kidney. [3H]Digoxin was instantaneously administered into the renal artery together with [14C]inulin and Evans blue-albumin, and renal venous and urinary outflow curves were measured. The ratio of fractional excretion to filtration fraction for digoxin was 2.40 +/- 0.40, indicating involvement of tubular secretion. Quinidine and verapamil decreased the ratio of fractional excretion to filtration fraction in a concentration-dependent manner, and this inhibition was indicated to occur at transport from cells to lumen across luminal membranes. Neither tetraethylammonium nor p-aminohippurate affected the renal handling of digoxin. Because ouabain and digitoxose showed no influence on the value of fractional excretion to filtration fractions, Na+,K(+)-ATPase is not involved in the tubular secretion of digoxin. A metabolic inhibitor, 2,4-dinitrophenol, markedly inhibited digoxin secretion. Agents that bind to P-glycoprotein, such as vinblastine, daunorubicin and reserpine, markedly inhibited the secretion of digoxin. Recently, we have found that digoxin is a substrate transported by P-glycoprotein. The findings obtained here support the hypothesis that digoxin is secreted by P-glycoprotein located on the luminal membrane of renal tubular epithelial cells, and that clinically important interactions with quinidine and verapamil are caused by the inhibition of P-glycoprotein.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed1992

Effect of l-menthol on the permeation of indomethacin, mannitol and cortisone through excised hairless mouse skin.

The effect of l-menthol on the skin permeability of mannitol, cortisone or indomethacin was examined by an in vitro penetration technique with hairless mouse skin. The donor solution was prepared with phosphate buffered saline, ethanol:buffered saline (20:80, v/v) or ethanol:buffered saline (20:80, v/v) containing 1% (w/v) l-menthol. Although ethanol showed little enhancing effect, l-menthol in an aqueous ethanol vehicle at pH 7.4 increased the permeability coefficients of mannitol and indomethacin by about 100 times that of the control (an aqueous vehicle) and increased that of cortisone by about 10 times. l-Menthol, however, scarcely enhanced the penetration of indomethacin at pH 3.0, the majority of the species being in unionized form. These results suggested that the menthol-ethanol-aqueous system enhanced skin permeability through a direct effect on the polar and/or lipid pathways, while the thermodynamic activity of the penetrant molecule in the delivery vehicle might also influence the effectiveness of the penetration enhancer.

Administration, Cutaneous↗

PubMed1992

Intracranial seeding following surgery for spinal cord astrocytoma--case report.

We report a case of intracranial dissemination developing approximately 6 months after partial removal of a spinal cord astrocytoma in a 40-year-old male. The clinical course and postmortem findings indicate that the tumor originated in the cervical cord and extended into the subarachnoid space, first the spinal canal and later intracranially. Spinal cord glioma dissemination through the cerebrospinal fluid is more common than previously considered and indicates a dismal prognosis. An aggressive approach, including radical surgery, entire neuraxis irradiation, and adjuvant chemotherapy, is suggested as the initial treatment for malignant spinal cord glioma to prevent subsequent dissemination.

Adult↗

PubMed1992

[Discrepancy between 123I-IMP SPECT and X-ray CT in chronic cerebrovascular disease].

The discrepancy between the low accumulation area (LAA) seen on 123I-IMP SPECT and the low density area (LDA) on X-ray CT was evaluated in 76 cases with chronic cerebrovascular disease. In 19 patients, LAA was larger than LDA beyond the vascular territory. Brain angiogram showed either obstruction or stenosis of the major arteries in as many as 59 percentages of this discrepancy group. In many patients of this group, cortical neurological symptoms were observed. In 37 patients in which the size of LAA was equal to that of LDA, abnormality of the major arteries was observed in only 7 percentages. These results indicated that the discrepancy mainly reflected the infarction due to irreversible ischemic change of perforate artery with the cortical low perfusion caused by the major artery disease. In some patients, the discrepancy was believed to show the remote effect caused by neurological pathway disturbance.

Adult↗

PubMed1991

Gonadotroph adenoma of the pituitary mimicking a prolactinoma.

In a 41-year-old woman with mild hyperprolactinemia and amenorrhea, preoperative hormonal and neuroradiological findings suggested the diagnosis of a macroprolactinoma. She underwent transsphenoidal surgery since the tumor size had not changed in spite of bromocriptine administration for 5 months. Consequently, this case was diagnosed as a female-type gonadotroph adenoma on the basis of its characteristic ultrastructural features including a honeycomb Golgi complex, even though endocrinological and immunohistochemical findings were not those of a typical gonadotroph adenoma.

Adenoma↗

PubMed1991

Enterogenous cyst of the cerebellopontine angle cistern: case report.

A case of an enterogenous cyst located in the cerebellopontine angle cistern is presented. These cysts have usually been found in the spinal canal, and their intracranial occurrence is exceptional. In the present case, the cyst was lined histologically by a single epithelial layer of cuboidal cells with some glandular structures resembling the fundic glands of the stomach. The unusual location of the cyst and its histological features are discussed.

Adult↗