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Biomedical subjects

H Oyama

Publications and source records attributed to H Oyama.

At least 91 records · Page 5Linked to original sources
PubMed1996

[Gamma knife treatment of AVM of the basal ganglia and thalamus].

Arteriovenous malformatios (AVMs) in the basal ganglia (BG) and thalamus (Thal) are difficult to treat by microsurgery or intravascular embolization alone, and the role of stereotactic gamma radiosurgery (gamma knife) of these AVMs is discussed. We have treated 324 cases of AVM with gamma knife since May 1991, and in 71 of these cases (19%) the AVM was in the BG or Thal. The results of gamma radiosurgery on AVMs of the BG and Thal were compared with the results of treating AVMs at other intracranial locations by gamma radiosurgery. The nidi were small (mean diameter: 16.4 mm), and they were treated with a mean maximum dose of 36.4 Gy and marginal dose of 19.9 Gy. The results were evaluated angiographically in 39 (55%) of the 71 cases, with a mean follow-up period of 23 months. The complete obliteration rate of AVMs in the BG and Thal 1 and 2 years after treatment was 54.3% and 92.0%, respectively, and the rate at the other locations was 42.9% and 76.0%, respectively. Adverse effects of this treatment in the AVM cases overall were rebleeding from the nidus in 5 cases (1.5%) and radiation necrosis in 4 cases (1.2%). In conclusion, AVMs of the BG and Thal were effectively and safely treated with the gamma knife, and stereotactic radiosurgery is a definitive alternative treatment for deep seated AVMs.

Adolescent↗
PubMed1996

[The results of gamma knife radiosurgery for malignant skull base tumors].

The results of gamma knife radiosurgery for malignant skull base tumors were analyzed using repeated magnetic resonance imagings and neurological examinations. Nineteen malignant skull base tumors were treated and followed up for 22.3 months (5-40 months) using MR imagings. The mean age was 54.4 years old (ranging from 16-85). Ten were male and 9 were female. Prior to the radiosurgery, removal of the tumors in 17 cases, conventional radiation therapy in 7, and chemotherapy in 4 etc. were performed. The pathological diagnoses were chordoma in 6 cases, metastatic tumors in 5, epipharyngeal carcinoma in 2, adenoid cystic carcinoma in 2, and others in 4. The locations of tumors were the clivus in 8, the parasellar region in 5, the epipharynx in 2, the paranasal sinus in 2, C-P angle in 1, and intraorbital region in 1 (14 were intracranial and 5 were extracranial). The mean diameter of the tumor was 33.5mm. The mean maximum dose was 26.8Gy and the mean marginal dose was 12.9Gy during treatment. Repeated MR imagings revealed decrease of tumor size in 12 cases, no change in 1, and increase of tumor size in 5 (unknown in 1). Follow-up neurological examinations showed improvement in 3 cases, no change in 9, and deterioration in 7. There were 11 deaths during a mean follow-up period of 17.8 months (5-32 months) and another 8 cases are alive for a mean follow-up of 30.5 months (20-40 months) after the radiosurgery. Although the tumor size was large at the time of treatment, the results of gamma knife radiosurgery were promising. Considering the quality of life of patients with malignant skull base tumors, it is emphasized that gamma knife treatment is the method of choice compared with radical removal of the tumors.

Adolescent↗
PubMed1996

[Incidence of cancer among Japanese patients with rheumatoid arthritis].

Most follow-up studies of patients with rheumatoid arthritis demonstrate no increase in the incidence of cancer apart from approximate doubling of the incidence of lymphoproliferative malignancies. A consecutive series of 1832 Japanese patients with rheumatoid arthritis seen at the center was studied to determine their cancer morbidity. Overall, 35 cancers were diagnosed in the series from 1982 through 1995 and were not significantly in excess of the expected number. No association was found between rheumatoid arthritis and subsequent development of cancer at any site, either.

Aged↗
PubMed1995

The possible role of linac-based stereotactic radiotherapy in the treatment of multifocally and heterochronously recurrent malignant astrocytomas. A case report.

We present a 24-year-old woman with multifocal and heterochronous recurrence of malignant astrocytomas that were consecutively treated by linac-based sterotactic radiotherapy. The patient had previously received multimodalities of treatment for malignant astrocytomas in the right occipital lobe consisting of surgical resection on four occasions, conventional external-beam irradiation, immunological therapy, and systemic chemotherapy. Thereafter she developed relatively small and well-demarcated recurrent lesions in eight different sites, most of which were located in eloquent and deep-seated regions. She underwent ten fractionated linac-based stereotactic radiotherapy courses with a median total dose of 42 Gy, seven fractions of 6 Gy each in 15 days, experiencing neither any adverse effects nor neurologic deterioration. Three out of 10 treated lesions responded well with subsequent reduction in size, and 80% of them did not increase at least for 6 months, although 66.7% of the lesions eventually exhibited enlargement of the enhanced areas, some of which were presumed as radiation necrosis. These clinical results suggest that the fractionated linac-based stereotactic radiotherapy had significant effects on tumor growth inhibition and attainment of acceptable patient performance status.

Adult↗
PubMed1995

Investigation of chemoresistance-related genes mRNA expression for selecting anticancer agents in successful adjuvant chemotherapy for a case of recurrent glioblastoma.

BACKGROUND: Glioblastoma multiforme represents one of the most malignant forms of primary intracranial tumors, often intractable to multimodality of treatment including chemotherapy. The unsatisfactory results of chemotherapy are chiefly attributed to chemoresistance. Since various molecules that could confer drug resistance have been elucidated, screening of the amount of such molecules in the tumor cells could provide possibilities for predicting their chemoresistance beforehand and help select more effective drugs. METHODS: We present a 45-year-old woman with recurrent glioblastoma multiforme in the cerebellum and invading the brain stem, treated successfully by postoperative chemotherapy. In this patient, anticancer drugs were determined by measurements of mRNA expression of chemoresistance-related genes, such as O6-methylguanine-DNA methyltransferase (MGMT), mdr1, glutathione S-transferase (GST)-pi, and metallothionein (MT) in the resected tumor. RESULTS: Northern blot analysis demonstrated the moderate mRNA level of MGMT, a major molecule causing ACNU (1-(4-amino-2-methyl-5-pyrimidinyl)methyl-3-(2-chloroethyl)-3-nitroso ure a hydrochloride) resistance. On the other hand, expression levels of mdr1 which codes the P-glycoprotein responsible for multidrug resistance, and GST-pi, a detoxification enzyme, were low. Transcript of MT, another thiol containing molecule for cellular detoxification possibly associated with cisdiamminedichloroplatinum(II) (CDDP) resistance, was only faintly detectable. Postoperatively, the patient was treated initially with intravenous administration of ACNU and etoposide (VP16), resulting in a minor response of tumor regression. For maintenance therapy, we changed ACNU to CDDP according to the findings of the Northern blot analysis. Consequently, the residual tumor showed a marked response and almost disappeared after two courses of systemic chemotherapy with CDDP and VP16. CONCLUSIONS: The successful tumor regression in this case suggests that Northern blot analysis on expression of these chemoresistance-related genes in tumor tissues could provide beneficial information for determination of optimal anticancer agents to improve the efficacy of chemotherapy.

Antineoplastic Agents↗
PubMed1995

Regional differences in cerebral vasomotor control by nitric oxide.

Regional differences in the role of nitric oxide in cerebral vasomotor control were investigated with a nitric oxide synthesis inhibitor, NG-monomethyl-L-arginine, or a precursor of nitric oxide, L-arginine using both dog cerebral angiography for the larger artery study and rat isolated arterioles for the microcirculation study. NG-monomethyl-L-arginine (10 mumol) constricted the dog cerebral arteries, by 15.6%, 17.5%, and 27.3% in the middle cerebral, anterior cerebral, and basilar arteries, respectively. The greater constriction of the basilar artery did not reach statistical significance. However, L-arginine (100 mumol) produced significantly greater dilation of basilar arteries than the middle cerebral or anterior cerebral (31.3% vs. 16.7% or 13.1%). NG-monomethyl-L-arginine at 10(-3) M constricted rat arterioles originating from basilar arteries significantly more than the middle cerebral arteries (23% vs. 14%). L-arginine at 10(-3) M dilated rat arterioles from basilar arteries significantly more than from the middle cerebral artery (24 vs. 11%). These findings suggest that the roles of nitric oxide in vasomotor control differs by region in the brain, and it may be greater in vessels of the posterior than of the anterior circulation.

Animals↗
PubMed1995

Partial purification and characterization of an esterase acting on the anticancer pro-drugs, 7-ethylcamptothecin derivatives.

A hydrolytic enzyme which catalyzes hydrolysis of the ester-linkage of a series of 17-O-acyl derivatives of 7-ethylcamptothecin-21-(2-dimethylamino)ethylamide [acyl derivatives of 22E] was purified from rat liver and its properties were characterized. It hydrolyzed the ester-linkage of all 22E derivatives tested as well as p-nitrophenyl acetate at pH 8-9 but had no effect on 7-ethyl-10-[4-(piperidino)-1-piperidino] carbonyloxycamptothecin (CPT-11: irinotecan), unlike CPT-11 converting carboxylesterase, which was previously purified from rat serum [Tsuji T. et al., J. Pharmacobio-Dyn., 14, 341 (1991)]. The enzyme had no effect on either acetyl choline or butyrylcholine. It was inhibited by several organophosphorous compounds such as diisopropyl fluorophosphate (DFP), bis-(p-nitrophenyl)phosphate and paraoxon, but was insensitive to inhibitors specific for choline esterases. These results indicate that this liver esterase is clearly distinct from choline esterase and serum CPT-11 converting enzyme and is able to convert pro-drugs, O-acyl derivatives of 22E, to an antitumor agent.

Animals↗
PubMed1995

Isolation and characterization of a novel 5-oxoprolinase (without ATP-hydrolyzing) from Alcaligenes faecalis N-38A.

A screening test was undertaken to isolate a microorganism that produced 5-oxoprolinase (without ATP-hydrolyzing). The 5-oxoprolinase (without ATP-hydrolyzing) activity (decyclization activity toward L-pyroglutamate) was found in a cell-free extract of Alcaligenes faecalis N-38A, newly isolated from a soil sample. The enzyme was purified as a homogeneous preparation. The molecular weight of the enzyme was estimated to be 47,000. The decyclization activity was specific for L-pyroglutamate, and independent of ATP and metal ions. The reaction was a reversible one, i.e., cyclization reaction of L-glutamate to yield pyroglutamate was identified.

Alcaligenes↗
PubMed1995

Hemifacial spasm in Albright's hereditary osteodystrophy with pseudopseudohypoparathyroidism and nephrogenic diabetes insipidus--case report.

A 30-year-old male with Albright's hereditary osteodystrophy, pseudopseudohypoparathyroidism, and nephrogenic diabetes insipidus presented with hemifacial spasm persisting for 2 years. This association is extremely unusual. Angiography revealed markedly tortuous carotid and vertebral arteries inconsistent with his age. Neurovascular decompression of the left vertebral artery achieved only partial resolution of the spasm.

Adult↗
PubMed1995

Subarachnoid hemorrhage of unknown origin associated with Weber-Christian disease--case report.

A 58-year-old female, who had suffered from Weber-Christian disease for 26 years, presented with subarachnoid hemorrhage. Cerebral angiography showed dilatation of the basilar tip. An operation was performed in the chronic stage. The wall of dilated basilar artery was tough, but that of the right superior cerebellar artery was very thin and three small aneurysms were found on the right middle cerebral artery. Blood levels of fibrin degradation products, plasmin-alpha 2-plasmin inhibitor complex, and thrombin-antithrombin III complex were increased. The abnormality of the coagulation-fibrinolysis system and the fragility of the cerebral arteries related to Weber-Christian disease were probably the cause of the subarachnoid hemorrhage.

Basilar Artery↗
PubMed1995

[Pneumocystis carinii pneumonia associated with low dose methotrexate treatment for malignant rheumatoid arthritis].

Low dose pulse methotrexate (MTX) has become a widely used therapy for rheumatoid arthritis (RA) because of its good response rate profile. With the increased use of MTX, reports of opportunistic infections associated with MTX therapy have appeared. Fourteen cases of pneumocystis carinii (PC) pneumonia in patients receiving low dose MTX have been previously reported. Yet, no case of PC pneumonia associated with low dose MTX has so far been reported in Japan. We report the first case in Japan of PC pneumonia occurring in a patient with rheumatoid vasculitis who was receiving low dose MTX. A 70-year old woman with 13 year history of RA presented with 3-day history of rapidly aggravating dyspnea, dry cough and fever. She had been receiving MTX 7.5 mg/week for 2.5 months because of her vasculitis symptoms. She had also been receiving prednisolone 7.5 mg/day which had been successfully tapered from an initial dose of 15 mg/day. At the time of her presentation with respiratory symptoms, all of her vasculitis symptoms had been alleviated. A chest radiograph revealed diffuse interstitial shadowing bilaterally and bilateral hilar and right lower lung field infiltrates. Her arterial blood gas showed severe hypoxemia (PaO2 27.7 torr). Polymerase chain reaction assay of bronchoalveolar lavage fluid showed PC. Although the patient required ventilatory support for 9 days, she was successfully treated with trimethoprime-sulphamethoxazole and methylprednisolone pulse therapy. Eight months later, the patient was well with no evidence of vasculitis or respiratory symptoms.

Aged↗
PubMed1995

[The comparison between adult and pediatric AVMs treated by gamma knife radiosurgery].

More than 290 cases of cerebral AVM had been treated by gamma knife radiosurgery since May, 1991, among which ninety-nine cases were angiographically followed up for at least one year. Comparison of the results between adult and pediatric AVMs were made. There were seventy six adult and twenty three child cases. Intracerebral hemorrhages in their past history were found in 73.7% of adult and 91.3% of child cases respectively, and the rate of intracranial hemorrhages in the pediatric group was higher than that in the adult group. The volume of the nidus of AVM in both groups was 4.2 ml in adults and 4.8 ml in children. Grade III of the Spetzler grading system occupied about 70% of all cases and was the most common grade in both groups. Treatment was performed with a mean marginal dose of 20.0Gy in adults and 20.5Gy in children. The complete occlusion of the nidus was obtained in 45% of the adult group and 74% of the pediatric group one year after, and in 81% and 95% respectively two years after the treatment was begun. As side effects, these were two rebleedings, one radiation necrosis and one radiation-induced edema in adults. However, no side effects were observed in children. It is considered that, when using gamma knife radiosurgery, pediatric AVMs are more likely to be occluded successfully and safely than adult AVMs.

Adolescent↗
PubMed1995

[A new strategy for the treatment of jugular foramen tumors using radiosurgery].

A new treatment strategy for jugular foramen tumors using radiosurgery is reported. Six jugular foramen tumors, including 2 glomus tumors and 4 lower cranial neurinomas, were involved. Among them only one tumor was confined in the jugular foramen, but the others extended into the posterior fossa, the upper cervical portion or both. As an initial treatment, 3 cases underwent operative resection from suboccipital or transcervical route. The tumor sizes at radiosurgery ranged from 14.3 to 36.1 mm with a mean of 22.4 mm in diameter. They were treated with a marginal dose between 13 to 16.5 Gy (mean 15.6 Gy). Follow-up MRI showed an apparent tumor shrinkage in 4 and no change in 2. Central tumor necrosis was found in 4 cases, but tumor progression was never observed in the mean follow-up period of 19 months. No complication occurred during and after the radiosurgery. These results indicate that radiosurgery is effective for the control of jugular foramen tumors with acceptable risk. Large tumors extending to the upper cervical portion and posterior fossa can be treated by operative resection combined with radiosurgery.

Adult↗
PubMed1995

[Sleep apnea syndrome in rheumatoid arthritis (RA) patients complicated with cervical and temporomandibular lesions].

All-night polysomnographic studies were performed on ten patients (all female) with rheumatoid arthritis complicated with temporomandibular joint destruction and cervical lesions. The mean age of these subjects was 67.5 yrs, ranging from 48-81 yr. They all had some morphologic abnormalities of cervical spines and/or temporomandibular joints. Sleep study revealed that all of them had sleep apnea; five of them were of obstructive type (obstructive group) while the remaining showed central type of sleep apnea (central group) predominantly. There were no statistically significant differences of the levels of apnea index, mean-nadir SO2 and the lowest SO2 between the obstructive group and the central group. No detectable differences of cephalographic measurements and MRI findings existed between the two groups either. In one patient, nasal-CPAP converted central apnea to normal breathing dramatically. Our observations indicate that the cause of central apnea in RA patients with temporomandibular lesions is collapse of upper airway, inducing inhibitory inputs from the mechanoreceptors in that region.

Aged↗
PubMed1995

[Percutaneous transluminal angioplasty for cervical carotid artery stenosis].

Percutaneous transluminal angioplasty (PTA) was attempted in 16 patients (17 procedures) with cervical internal carotid artery (ICA) stenosis. Among the 16 patients, 14 were male and 2 were female aged from 44 to 76 years (average 63.4 years). One had cerebral infarction on the acute stage, and the other 15 were in the chronic stage. On CT scan and MRI, there were nine multiple lacunar infarctions and seven watershed infarctions. On angiographical findings, 13 had Rt.-ICA stenosis and 4 had Lt. ICA stenosis. Stenotic lesion existed beyond the level of the third cervical vertebral body in eleven cases, and so-called long segmental stenosis ranged from 3 to 5 cervical vertebral bodies in 3 cases. Before PTA, 14 patients underwent a balloon occlusion test for 3 to 20 minutes (average 9 minutes). Neurological symptoms of hemiparesis or sensory disturbance occurred in 3 patients during balloon inflation, but these disappeared completely after balloon deflation. It took from 1.5 to 2 hours (average 1.7 hours) to carry out PTA including the balloon occlusion test. All cases had satisfactory results with no morbidity or mortality. The mean stenosis ratio of pre-PTA, approximately 80% (55-93%), improved to that of 22% (0-50%) after PTA. Bradycardia and hypotension occurred transiently in 9 cases during and after PTA, but no symptoms remained by atropine sulfate and catecholamine infusion intravenously. In the following 1 to 26 months (mean 9.0 months) after PTA, 3 cases restenosed. The restenosis was recognized by MR angiography after 8 to 26 months (average 15.7 months) of PTA.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Ossified and calcified epidural hematoma incidentally found 40 years after head injury: case report.

The authors report a 57-year-old man with an ossified and calcified epidural hematoma found incidentally 40 years after incurring a severe head injury. Since the introduction of computed tomography (CT) scan, few such cases have been described in the literature. A characteristic intracranial "double-outlined" contour on plain skull x-ray films and CT scans represented bone formation and calcification of the hematoma capsule adjacent to the dura.

Calcinosis↗