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Biomedical subjects

T Okabe

Publications and source records attributed to T Okabe.

At least 559 records · Page 31Linked to original sources
PubMedDate not supplied

Change in creep rate and microstructure in an aged, low-copper amalgam.

Low-copper amalgams aged at 37 degrees C, 50 degrees C, 60 degrees C, 70 degrees C, and 80 degrees C for periods of 7 and 30 days were examined using a scanning electron microscope and an x-ray diffractometer. Gamma-one Ag-Hg grain size and gamma 2 Sn-Hg volume fraction, and surface area were determined by quantitative metallography. At 60 degrees C and below, gamma 1 was the predominant matrix phase. Little beta 1 Ag-Hg was found. In this temperature range, both gamma 1 grain size and ADA creep were found to obey an Arrhenius law. A linear relationship was found between the log of the mean ADA creep and the mean gamma 1 grain size. Above 60 degrees C, the gamma 1 phases and the majority of the gamma Ag-Sn particles disappeared. In their place, beta 1 appeared. Gamma-two volume fraction increased during aging at temperatures over 60 degrees C, but a coarsening of gamma 2, reflected in a decrease in gamma 2 surface area per unit volume, also took place. Aging for 30 days or less resulted in decreases in ADA creep. At 60 degrees C and below, the decrease was caused by increases in gamma 1 grain size. Above 60 degrees C, the decrease in ADA creep was caused by several factors, one of which was the appearance of large beta 1 grains.

Copper↗
PubMedDate not supplied

Development of medical information transfer system using personal-agent optical disks.

The establishment of a better local area medical centre containing hospitals and clinics is thought to be a very important issue. The medical information system, which should be accepted by both hospitals and clinics, has been studied using graphic user interface (GUI) and a three dimensional structure. Our system files medical records and blood examination data as well as diagnostic images, which may be the first attempt in the world. It has been favourably evaluated by physicians through clinical evaluation.

Evaluation Studies as Topic↗
PubMedDate not supplied

Coexistence of lymphoblastic and monoblastic populations with identical mixed lineage leukemia gene rearrangements and shared immunoglobulin heavy chain rearrangements in leukemia developed in utero.

Congenital leukemia often provides insight into mechanisms of in utero leukemogenesis. A 10-day-old boy with clinical features of skin nodules, marked hepatosplenomegaly, and subcutaneous bleeding received a diagnosis of congenital leukemia. This patient initially had a dominant B progenitor lymphoblast population and minor monocyte component. Treatment with prednisolone, vincristine, and doxorubicin resulted in a loss of lymphoblast population and a rapid increase and dominance of the monocyte component within 10 days. Complete remission initially was obtained with additional combination chemotherapy with epipodophyllotoxin (VP-16) and cytosine arabinoside (Ara-C), but relapse characterized by a lymphoblastic population in the bone marrow was subsequently observed. The authors hypothesize that the leukemic cells originated from a common B-monocyte lineage stem cell during fetal hematopoiesis.

Gene Rearrangement↗
PubMedDate not supplied

Redistribution of cerebral blood flow following STA-MCA by-pass in patients with hemispheric ischemia.

Regional cerebral blood flow and vasomotor reactivity were measured in 33 patients with surgically remediable hemispheric ischemia by the 133Xe inhalation method prior to superficial temporal to middle cerebral artery (STA-MCA) by-pass. Thirteen patients also underwent LCBF and L lambda measurements by the stable xenon CT method for comparison. Twenty-four had proximal occlusion of one or both internal carotid arteries, 9 had intracranial occlusive disease (4 internal carotid, 5 middle cerebral). Measurements were repeated at intervals up to 30 months following surgery and compared to measurements in a similar group (N = 13) treated medically. In the surgically treated group 22 patients had recurrent TIAs, of whom 12 also had minor residual neurological deficits from recent small cerebral infarctions with potential for recovery (RINDs) while the remaining 11 had RINDs without TIAs. After surgery 28 improved with cessation of TIAs and/or neurological recovery, 3 remained unchanged, 2 cases worsened. Compared to age-matched normal hemispheric F1 (gray matter) values, pre-operative F1 values in the STA-MCA group were reduced in both ischemic and opposite hemispheres. Ischemic regions showed imparied vasomotor reactivity to 5% CO2 or 100% O2 inhalation. After surgery, mean hemispheric F1 values increased + 12.8% on the by-pass side and + 10.5% on the contralateral side. Mean F1 increases reached a maximum 3 months after by-pass, most evident in ipsilateral frontal regions (+ 24.2%). Vasomotor reactivity did not significantly improve. Medically treated cases did not show similar F1 increases. Thirteen with carotid occlusive disease (8 with TIAs, 5 with small recent infarcts) underwent CT LCBF and L lambda measurements before and after STA-MCA by-pass. Cases with recent infarcts showed reduced LCBF and L lambda values which increased significantly after STA-MCA by-pass, however the total group operated upon showed only trends for CBF increases, probably due to large standard deviations encountered in serial measurements.

Aged↗
PubMedDate not supplied

Stable xenon CT CBF measurements in prevalent cerebrovascular disorders (stroke).

Local cerebral blood flow (LCBF) and local tissue: blood partition coefficient (L lambda) values were measured for small volumes of gray or white matter by CT CBF. Single compartment analysis was used but fitted to infinity in normal volunteers aged between 20 to 100 years (N = 20). Hemispheric LCBF and L lambda values were compared to those of 61 age matched patients with transient ischemic attacks (TIAs, N = 10), reversible ischemic neurologic deficits (RINDS, N = 10), acute and chronic cerebral infarctions associated with emboli from atherosclerotic plaques or complete occlusion of internal carotid or middle cerebral arteries (n = 9) or of cardiac origin (N = 3), cerebral hemorrhage (N = 1), multi-infarct dementia (MID) (N = 11) and arteriovenous malformations (AVM) (N = 17). In normal aging, L lambda s were normal, but LCBF showed diffuse age-related declines. Symptomatic cerebrovascular disease was characterized by accentuation of age-related LCBF declines. TIAs with unilateral ICA occlusion showed bilateral reductions of LCBF more evident in ischemic hemispheres. TIAs due to fibrino-platelet emboli from ulcerated, non-occlusive ICA plaques were characterized by transient unilateral, localized LCBF reductions. All TIAs showed normal L lambda values. RINDS showed both LCBF and L lambda reductions. Larger embolic infarctions of ICA origin, whether acute or chronic, showed zones of zero flow with surrounding reductions of LCBF and L lambda values. Recent cerebral embolism of cardiac origin likewise exhibited zones of zero flow surrounded by reduced LCBF and L lambda values; but in chronic stages LCBF and L lambda values adjacent to zero flow zones were normal. MID was characterized by patchy reductions of LCBF and L lambda values throughout both hemispheres. Brain tissues surrounding AVM showed normal L lambda values but LCBF values were reduced due to steal.

Adult↗
PubMedDate not supplied

New information on high copper amalgam corrosion.

Anodic polarization of "pure" Cu6Sn5 was investigated. Cu6Sn5 is found to be passive in nearly neutral synthetic saliva. Anodic corrosion activity (characteristic for tin) previously reported for a high copper amalgam must result from the presence of the gamma2 phase or tin in the matrix phase.

Chemical Phenomena↗
PubMedDate not supplied

Rate of eating and body weight in patients with type 2 diabetes or hyperlipidaemia.

This preliminary investigation, involving 422 patients, tested the hypothesis that rate of eating is associated with obesity in patients with type 2 diabetes or hyperlipidaemia at all ages. The patients' eating habits were determined using a questionnaire, and the patients were classified as quick, normal or slow eaters. The body mass indices of the three groups were compared. The body mass indices of the male patients who ate quickly (25.4 +/- 0.2 kg/m2) were significantly higher than those of the patients who ate at a normal rate (24.4 +/- 0.3 kg/m2) or slowly (24.1 +/- 0.5 kg/m2). No difference between body mass indices in the female groups was found. It was speculated that rate of eating affects body weight in male patients with type 2 diabetes or hyperlipidaemia.

Adult↗