Search PubMed⌕ Search

Biomedical subjects

R Tanaka

Publications and source records attributed to R Tanaka.

At least 505 records · Page 28Linked to original sources
PubMed1991

Discrimination of different motor units by spike-triggered averaging of surface electromyograms.

An objective method was sought for the discrimination of individual motor units (MUs). Discrimination using the conventional needle electrode recording is difficult because the waveforms are easily changed by slight shifts of the electrode. A surface EMG recording was combined with the needle recording and MU activities were obtained by MU-triggered averaging of the surface EMGs. Waveforms of surface MU potentials were stable, irrelevant to changes in recording conditions of needle electrodes and thus were found useful for the purpose of discrimination. Efficacy of this method was tested in the MUs with known axonal conduction velocities.

Action Potentials↗
PubMed1991

Serial angiography in a spontaneous dissecting anterior cerebral artery aneurysm.

Intracranial dissecting aneurysms are uncommon, and little is known concerning the natural history of these lesions. In this paper we present a rare case of dissecting aneurysm of the anterior cerebral artery in which a true diagnostic sign of "double lumen" was demonstrated. Sequential changes in angiographic features shown on serial angiographic studies are described, and diagnosis is briefly discussed.

Aortic Dissection↗
PubMed1991

Asymptomatic constant isolated proteinuria in children.

The clinical features, renal biopsy findings, and subsequent course in 53 children with asymptomatic constant isolated proteinuria were studied retrospectively (1) to determine the prevalence of renal pathologic abnormalities among these children, (2) to identify those clinical characteristics that may enable recognition of children with an increased likelihood of having renal pathologic abnormalities, and (3) to assess the clinical course. All biopsy specimens were examined by light, immunofluorescence, and electron microscopy. Twenty-five patients (47%) had significant glomerular changes (15 had focal segmental glomerulosclerosis, 4 IgA nephropathy, 3 diffuse mesangial proliferative glomerulonephritis without IgA deposition, and 3 membranous glomerulonephritis), and 28 had minimal glomerular changes. There were no differences between the patients with significant glomerular changes and those with minimal glomerular changes with regard to clinical and laboratory findings except for a predominance of boys in the former group. At the latest follow-up, seven patients with significant glomerular changes, but none with minimal glomerular changes, had chronic renal impairment. Because of the high incidence of significant glomerular changes and the high rate of progression to chronic renal impairment, we believe that a renal biopsy is indicated for a child with asymptomatic constant isolated proteinuria.

Adolescent↗
PubMed1991

Effects of radiation on capillary endothelial cells derived from Mongolian gerbil brain.

Confluent monolayers of capillary endothelial cells derived from Mongolian gerbil brain were irradiated with a single exposure of x-rays, and their radiosensitivity and sequential changes in morphology and capacity to produce prostacyclin were examined. The radiobiological parameters that characterized the dose-response survival curve of these cells were found to be n = 1.9, Dq = 120 rad, and Do = 190 rad. Morphologically, nuclear and cytoplasmic swelling, vacuolation of cytoplasm, and giant cell formation occurred in a dose-dependent manner beginning as early as 24 hours after irradiation. The capacity to produce prostacyclin was significantly enhanced at 24 hours, but less significant at 72 hours after irradiation. The present study suggests that the radiosensitivity of brain capillary endothelial cells is lower than that of endothelial cells originating from larger vessels, and that their changes in morphology and capacity to produce prostacyclin are similar to those of endothelial cells derived from larger vessels.

Animals↗
PubMed1991

Creutzfeldt-Jakob disease in a patient with a cadaveric dural graft.

We report a 26-year-old woman with Creutzfeldt-Jakob disease (CJD) who had received cadaveric dural material 33 months before the onset of neurologic symptoms. This is the fourth case in which a dural graft was the putative source of the CJD agent. All four cases had the grafting before changes in the sterilization procedure adopted in 1987 to inactivate the CJD agent.

Adult↗
PubMed1991

Studies on the constituents of Luffa acutangula Roxb. I. Structures of acutosides A--G, oleanane-type triterpene saponins isolated from the herb.

From the herb of Luffa acutangula ROXB. (Cucurbitaceae), seven oleanane-type triterpene saponins, acutosides A--G, were isolated and their structures were determined. Acutoside A is oleanolic acid 3-O-beta-D-glucopyranosyl-(1----2)-beta-D-glucopyranoside. Acutosides B, D, E, F and G have a common prosapogenin structure, acutoside A, and only differ in the structures of the ester-linked sugar moieties. Acutoside B is a 28-O-[O-beta-D-xylopyranosyl-(1----4)-O-alpha-L-rhamnopyranosyl-(1----2) -alpha-L-arabinopyranosyl] ester, D is a 28-O-[O-beta-D-xylopyranosyl-(1----3)-O-beta-D-xylopyranosyl-(1----4)-O- alpha-L-rhamnopyranosyl-(1----2)-alpha-L-arabinopyranosyl] ester, E is a 28-O-[O-alpha-L-arabinopyranosyl-(1----3)-O-beta-D-xylopyranosyl-( 1----4)-O-alpha-L-rhamnopyranosyl-(1----2)-alpha-L-arabinopyranosyl] ester, F is a 28-O-[O-beta-D-xylopyranosyl-(1----3)-[O-beta-D-xylopyranosyl-(1----4)-O -alpha-L-rhamnopyranosyl-(1----2)-alpha-L-arabinopyranosyl] ester, and G is a 28-O-beta-D-xylopyranosyl-(1----3)-[O-alpha-L-arabinopyranosyl-(1- ---3)-O-beta-D-xylopyranosyl-(1----4)]-O-alpha-L- rhamnopyranosyl-(1----2)-alpha-L-arabinopyranosyl] ester. Acutoside C is a machaelinic acid (=21 beta-hydroxyoleanolic acid) saponin having the same sugar moiety as that of acutoside B.

Carbohydrate Sequence↗
PubMed1991

Prevalence of chondrocalcinosis in patients with primary hyperparathyroidism in Japan.

One hundred and thirty-two consecutive patients with primary hyperparathyroidism were studied preoperatively for the presence of chondrocalcinosis, the roentgenographic marker of calcium pyrophosphate dihydrate (CPPD) crystal deposition disease, by obtaining radiographs of knees, wrists and pelvis. Chondrocalcinosis was found in 8 patients (6.1%), each of whom was over 50 years of age. In 72 of the patients over 50 years of age, the prevalence of chondrocalcinosis in the hyperparathyroid patients (11.1%) was greater than that found in 72 control patients (2.8%) with thyroid nodular disease who were exactly matched for age and sex, but the difference was not significant. The prevalence of chondrocalcinosis in the hyperparathyroid patients sharply increased with age. In the group in their 50's it was 4.4%, rising to 15.8% in patients in their 60's and reaching 37.5% for those over 70 years of age. Patients with chondrocalcinosis were significantly older than those without this finding (p < 0.005). Those with chondrocalcinosis also had significantly higher preoperative serum calcium levels than those without it (p < 0.05). While chondrocalcinosis was detected by taking joint radiographs in all patients with primary hyperparathyroidism, acute arthritis (pseudogout attack) occurred in only 2 of the 132 patients (1.5%) after parathyroidectomy, but this represents 25% (2 of 8) of those who had chondrocalcinosis. An attack of pseudogout may therefore be one of the most common postoperative complications of parathyroid surgery in the elderly. Considering the low incidence of pseudogout attack following parathyroidectomy, preoperative radiological studies of the knee joints are sufficient to screen for chondrocalcinosis and are recommended for patients over 60 years old in Japan.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1991

Serological analysis of tumor antigens in malignant glioma patients.

Sera from 27 malignant glioma patients were tested for antibodies to surface antigens of cultured human glioma cells using enzyme-linked immunosorbent assay. Average antibody titer for glioma cell lines was 0.558 +/- 0.123, which was significantly higher than in the normal control group (0.165 +/- 0.082). Surprisingly, average antibody titer for autologous glioma cells was low (0.207 +/- 0.154) in these patients. The results suggest that various surface antigens in glioma cells include specific autologous antigens, antigens associated with gliomas, and common antigens present on cultured normal and malignant cells. These analyses are important in the evaluation of monoclonal antibodies and explanation of escape mechanisms.

Adolescent↗
PubMed1991

Expression of MHC class II antigens on human glioma cells modulated by transfection with genes encoding these antigens.

Four glioma cell lines not expressing human leukocyte antigen (HLA)-DR or DQ did so after transfection with genes encoding HLA-DR and DQ. The glioma cells had enhanced ability to stimulate allogeneic and autologous responding lymphocytes in the mixed lymphocyte response (MLR). Glioma cells expressing only HLA-DR had weaker MLR enhancement than those expressing both HLA-DR and DQ or only HLA-DQ. Stimulation by transformed glioma cells increased the killing activity of responding lymphocytes against autologous glioma cells 2.0 times. Both HLA-DR and DQ are important in MLR, and the immunogenicity of glioma cells might be increased by transfection with genes encoding these antigens.

Antigens, Neoplasm↗
PubMed1991

Subarachnoid hemorrhage from a dissecting aneurysm of the middle cerebral artery. Case report.

A case of subarachnoid hemorrhage (SAH) from a dissecting aneurysm of the inferior limb of the middle cerebral artery is reported. The patient's clinical status and the initial and follow-up angiographic appearance of the aneurysm are presented. Diagnosis and treatment are briefly discussed. It is suggested that, if angiography demonstrates luminal narrowing or vascular occlusion in a patient with unexplained SAH, a dissecting aneurysm of the carotid system should be considered as a cause of the hemorrhage.

Adult↗
PubMed1991

A clinicopathological study of dissecting aneurysms of the intracranial vertebral artery.

Five autopsied cases of dissecting aneurysms of the intracranial vertebral artery are reported and the literature is reviewed to clarify the clinicopathological correlations. In an autopsy series of 110 patients with subarachnoid hemorrhage (SAH), the incidence of this entity was 4.5%, with all five cases progressing rapidly to death from massive SAH. Cases of intracranial vertebral dissection can be divided clearly into two groups based on the clinical and pathological features. In the first group, the dissection is confined to the vertebral artery and a massive SAH develops caused by the rupture of the arterial wall. The plane of dissection is mainly subadventitial. In the second group, brain-stem infarction develops resulting from luminal occlusion by intramural hematoma. The plane of dissection is mainly subintimal, with the dissection extending to the basilar artery. The condition in the second group affects patients at a younger age. If the lesion is localized within the vertebral artery and does not extend to the basilar artery, the disease seems not to be fatal. The clinical features of the vertebral dissection are largely determined by the plane and extension of dissection. Vertebral artery dissection is due to many causative factors including hypertension, congenital or degenerative changes in the arterial wall, and anatomical and pathological characteristics of the vertebral artery.

Adult↗
PubMed1991

[Spinal reflex].

Explore the source record for details and available documents.

Electromyography↗
PubMed1991

In vivo sodium-23 MRI in brain tumors: evaluation of preliminary clinical experience.

In vivo sodium-23 magnetic resonance (MR) imaging in the head was performed in ten normal volunteers and six patients with brain tumors on a commercially available 1.5 Tesla whole-body MR system. Although sodium MR signal from the brain parenchyma could hardly be detected on routine spin echo (SE) pulse sequence, free induction decay (FID) image with echo time of 1.9 msec demonstrated MR signal in the normal brain tissue. On the other hand, extracellular sodium of cerebrospinal fluid, large venous sinus, and vitreous humor offered high sodium MR signal intensity due to the quantity of sodium and the relatively longer transverse relaxation time (50-60 msec) compared to that of intracellular sodium (less than a few msec). Strong signal was obtained in gliomas with superior contrast, though the delineation of the tumor tissue from edema was as difficult as when seen on proton T2 weighted SE image. Meningioma itself gave much less of a sodium MR signal compared to glioma. Peritumoral edema associated with meningioma showed a markedly high sodium MR signal which was more prominent adjacent to the tumor, although proton SE image revealed the peritumoral edema as homogeneous. Pathological tissues such as brain tumors and edema could be readily depicted as significantly high sodium-23 MR signal, apparently different from normal brain tissues. The current status of in vivo sodium MR imaging is discussed. The authors concluded that early clinical experience of in vivo sodium-23 MR imaging brought promising results in the evaluation of brain tumors and edema; otherwise, discrimination and quantification of multiple T2 components and the improvement of spatial resolution are desperately needed.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

[The anesthetic management of a patient with the malignant hyperthermia trait diagnosed preoperatively].

A patient for fixation of ankle arthrodesis diagnosed as having malignant hyperthermia trait preoperatively is reported. A 17 year old man was anesthetized with enflurane for orthopedic surgery of the knee joint. At that time malignant hyperthermia developed. He was critically ill, but resuscitated and recovered from acute renal failure on 7th day after operation. Ca2+ release test was performed. Ca2+ releasing speed was prominently accelerated in this patient. We could identify him as having malignant hyperthermia trait. Epidural anesthesia with procaine chloride was given cautiously. No drug which may induce malignant hyperthermia was used. Nevertheless, malignant hyperthermia occurred. This disease has various forms of presentation. The mechanism is equivocal, and in some cases, it is difficult to judge it immediately. This patient was managed without complication. We consider that tourniquet and stress provoked signs of malignant hyperthermia in this patient.

Adolescent↗