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Biomedical subjects

T Okada

Publications and source records attributed to T Okada.

At least 793 records · Page 44Linked to original sources
PubMed1990

[Treatment and analysis of a clinical case of gingival pigmentation around the restored teeth].

A remarkable gingival pigmentation around the restorated teeth was successfully treated by simple surgical removal; incision & coagulasion of deposits by electrosurgery. Before the treatment, a biopsy from the pigmented gingiva was histopathologically examined, and a lot of small pigment deposits were found in the lamina propria with no inflammation, but not in the epitherium. Elements constructing the deposits were also determined by means of an electron probe X-ray microanalyser. Silver was found to be the principal element of the deposits, but not found at all in the crown metal. These results suggested that the cause of the pigmentation was implantation of metal fragments from metal cores during abutment teeth preparation. Therefore, the surgical removal was performed. Relapses have not occurred for 3 years since the treatment.

Electron Probe Microanalysis↗
PubMed1990

[The study on retention of adhesive restoration].

Although the prognoses of the adhesive bridges are practically satisfactory, some disconnections have been reported. Physical bite, twisting and tearing forces are considered to be the causes for these disconnections. Paired natural human teeth; 2 incisal and 2 molar teeth, were embedded in cold cured resin for fatigue test and axial reduction was slightly performed. Cast bridges which were designed to come to 30 mm2 in every abutment and to resemble clinical design, were made from two kinds of metal; Ni-Cr alloy and Ag-Pd-Au alloy, and adhered with teeth by Panavia EX (Kurarey Co. Ltd.). Incisal bridges were disconnected easier than molar bridges in the fatigue test. There was no significant difference between 2 kinds of metal. With stereoscopic microscope, cohesive fracture of resin was observed on the region which was farthest from supporting point of fatigue force in incisal bridges. Dimple patterns characteristically in fatigue fracture were also observed in some cases. In modified tensile test of incisal teeth using Ni-Cr alloy, force point was given far 1 mm & 12 mm apart from approximal surface, and various twisting and tearing forces were loaded in 12 mm cases. The cases loaded by higher twisting and tearing forces had significantly smaller bond strength.

Chromium Alloys↗
PubMed1990

Distinct surface phenotypes of B cells responsible for spontaneous production of IgM and IgG anti-DNA antibodies in autoimmune-prone NZB x NZW F1 mice.

Autoimmune-prone NZB x NZW F1 (B/W F1) mice produce a high titer of anti-DNA antibodies, In vivo and in vitro studies showed that in the early life of these mice, the immunoglobulin isotype of these antibodies almost exclusively belongs to IgM class, however, IgG anti-DNA antibodies begin to develop when the mice are about 5-6 months old and the titer exceeds that of IgM antibodies from age 7 months on. We asked whether or not the B cell population responsible for IgM and IgG antibody production belongs to the same lineage. The surface phenotypes of B cell populations responsible for the spontaneous production of either IgM or IgG anti-DNA antibodies were examined using panning and sorting methods with several monoclonal antibodies to B cells, including CD5 (Ly-1) and Lp-3; the latter defines a unique B cell differentiation antigen. We obtained evidence that surface phenotypes of B cells secreting IgM anti-DNA antibodies belong to CD5+ Lp-3- and those of B cells secreting IgG anti-DNA antibodies which occur only in old B/W F1 mice belong to CD5- Lp-3+ subpopulations. The majority of peritoneal B cells were CD5+ Lp-3+ throughout the life span of the mice and anti-DNA antibody production was never evidenced. These findings were discussed in relation to age-associated changes of B cell populations in the spleen of this strain of mice.

Aging↗
PubMed1990

The significance of morphological changes in cerebral arteries after subarachnoid hemorrhage.

A porcine model was developed to allow quantitative assessment of morphological changes in cerebral arteries after subarachnoid hemorrhage and to determine the significance of structural changes in producing arterial narrowing. Whole blood was selectively applied to the middle cerebral artery (MCA) of seven pigs. After 10 days, vessels were perfusion-fixed and examined by light and transmission electron microscopy and immunohistochemistry. The MCA's exposed to whole blood for 10 days showed prominent luminal narrowing associated with profound ultrastructural changes affecting all layers of the vessel wall. Morphometric analysis, however, demonstrated that significant reductions in the luminal cross-sectional area (-55.8% +/- 12.5%, p less than 0.005) and increases in radial wall thickness (75.1% +/- 10.5%, p less than 0.005) were associated with only minimal increase in the cross-sectional area of the vessel wall (12.5% +/- 15%, p less than 0.025). By stereological analysis, the volume density of individual components of the arterial wall was unchanged in MCA's exposed to blood. Vessels exposed to blood showed a 44% reduction in smooth-muscle cell immunoreactive actin and increased collagen in the extracellular matrix of the vessel wall. These data suggest that structural changes in cerebral arteries after subarachnoid hemorrhage do not directly contribute to vessel narrowing through increases in wall mass. Nevertheless, such changes may reflect pathological mechanisms which act to augment prolonged vasoconstriction or inhibit the maintenance of normal vascular tone.

Animals↗
PubMed1990

The role of hemoglobin in arterial narrowing after subarachnoid hemorrhage.

A porcine model for subarachnoid hemorrhage has been developed to allow the selective application of blood and its components to cerebral arteries. Whole blood was centrifuged to produce two fractions consisting of washed erythrocytes (red blood cells, RBC's) and white blood cells (WBC) plus platelet-rich plasma (PRP); the RBC fraction was subsequently separated into hemoglobin (Hb)-containing cytosol and erythrocyte membranes. Each fraction was selectively applied to the middle cerebral artery (MCA) of pigs for 10 days; after which, vessels were perfusion-fixed and examined by light and transmission electron microscopy and immunohistochemical studies. By morphometric analysis, a marked reduction in the MCA lumen cross-sectional area was observed after selective application of RBC's or Hb/cytosol but not of WBC/PRP or erythrocyte membranes. In both RBC- and Hb/cytosol-treated vessels, luminal narrowing was associated with a differential increase in vessel wall thickness of the ventral (subarachnoid) compared to the dorsal (brain) aspect of the artery, but no significant change in cross-sectional area of the vessel wall. After 10 days of exposure to RBC's or Hb/cytosol, there was a spectrum of ultrastructural changes in the vessel wall comparable to those seen after periadventitial application of whole blood. Selective application of commercially available Hb to MCA produced similar structural and morphometric changes. The degree of luminal narrowing after exposure to whole blood or RBC's was proportional to the volume of the erythrocyte mass adjacent to the vessel at sacrifice. These data suggest that arterial narrowing after SAH is mediated by mechanisms related to prolonged exposure of the vessel wall to hemoglobin or its catabolites from lysing subarachnoid erythrocytes.

Animals↗
PubMed1990

[Self-esteem and anthrophobic-tendency in adolescents].

This study attempted to clarify the relationship between self-esteem and anthrophobic-tendency in normal adolescents. Two questionnaires measuring self-esteem and anthrophobic-tendency were administered to junior and senior high school students, and college students. The results show that for the junior high school and college students, self-esteem and anthrophobic-tendency correlated negatively, while there was an uncorrelativeness for the senior high school students. During senior high school age, they tend to estimate themselves in terms of their own standards rather than others', which result in little correlations between self-esteem and anthrophobic-tendency. The conflict between one's autistic tendency and interpersonal relations tends to lead to the anthrophobic-tendency.

Adolescent↗
PubMed1990

Thrombospondin deposition in rat carotid artery injury.

The balloon catheter injury model was used to determine the relative contributions of vascular smooth muscle cells (SMC) and platelets to thrombospondin (TSP) antigen deposition in the artery wall. Rat carotid arteries were denuded of endothelium, exposing the thrombogenic subendothelial extracellular matrix (ECM) to the circulation. Rats were killed after 1 hour, or 5, 10, or 20 days. Thrombospondin antigen deposition in the injured arteries was assessed using a specific polyclonal antiserum raised in rabbit against rat platelet TSP and a sensitive silver-enhanced immunogold staining method. Faint immunostaining for TSP antigen was detected, associated mostly with cells, in the media of the carotid artery of the nonoperated controls. One hour after balloon catheter injury, however, prominent cell-associated immunostaining was evident in the media; extracellular matrix staining was negligible. At this time, large foci of immunostaining were present on the lumenal surface of the vessel. Intimal proliferation was evident on most stained sections of tissue taken 5 days after balloon injury. Thrombospondin antigen immunostaining was markedly increased compared to nonoperated controls in all sections, regardless of the degree of intimal thickening. Thrombospondin immunostaining remained associated with cells in the neointima and media; extracellular matrix staining remained negligible. Ten days after endothelial injury, immunostaining for TSP antigen was detected in all layers of the artery, but was greater in the neointima and media. Reaction product was still associated only with cells. Thrombospondin antigen levels, as detected by this procedure, remained high in the injured tissue through 10 days of observation but appeared less prominent 20 days after injury. At this time extracellular matrix staining was obvious and cell-associated staining was reduced. These data support the hypotheses that thrombospondin (TSP) expression by vascular smooth muscle cells is an early response to injury and that the primary source of TSP antigen in injured artery is the vascular smooth muscle cells (SMC). These results support data derived from in vitro studies of TSP secretion.

Animals↗
PubMed1990

Long-term follow-up of a child with idiopathic restrictive cardiomyopathy.

A ten-year-old male with palpebral edema was proved to have a restrictive hemodynamic pattern by cardiac catheterization. Sequential echocardiographic examination revealed uniformly depressed left ventricular diastolic properties, well-maintained left ventricular systolic function, and a progression of obliterative change of the left ventricular cavity. Myocardial biopsy at 17 years of age disclosed a normal endocardium and marked interstitial fibrosis of the myocardium. Consequently, a decrease of cardiac output and a marked biatrial enlargement have developed in association with persistent atrial fibrillation.

Adolescent↗
PubMed1990

Development of EEG background activity in children with benign partial epilepsy.

We investigated the developmental features of the EEG-background activity of the 30 patients with benign childhood epilepsy. We found significant spectral differences between the benign childhood epilepsy group (BECCT; 25 cases, CEOP; 5 cases) and the normal control group. Compared with the normal group, the epilepsy group showed a shift of the spectrum to slower frequencies, with an increase in Delta and Theta, and a decrease in Alpha 2. The decrease in the mean frequency (O1) was significant from 8 years old to 10 years old. But in both the following periods; before 8 years old and after 10 years old, the difference was not significant. In the patients with benign childhood epilepsy, the development of the EEG-background activity came to be stagnant from 6 years old or so, and after 10 years old it developed again and approached to that of the normal children. It is suspected that the EEG background activity of children with benign partial epilepsy shows a special development.

Brain Mapping↗
PubMed1990

[Effects of load and loading time on fracture toughness with indentation method].

For clinical application of ceramics such as porcelains that are frequently used as crown restoration materials, it is important to quantitatively evaluate and determine brittleness. This quality is expressed as a fracture toughness value, KIC, but no distinct method for its determination has yet been established. In order to standardize conditions for the determination of KIC by the indentation method, effects of indentation load and loading time on KIC of calcium phosphate crystalline ceramics (CP) were studied at various Vickers indentation loads and various loading times in CP plate-like segments. Furthermore, plate-like segments of each of CP, apatite (AP), mica-beta-spodumene (MIS) and mica (MIC) groups were subjected to experiment at various indentation loads at a fixed loading time to study the effects of indentation load on KIC in four kinds of Castable Ceramics. The results are summarized as follows: 1) The Vickers hardness degree of CP was decreased with an increase in indentation load and loading time, reaching the maximum value (499Hv) at 1kgf of indentation load and 5s of loading time. 2) The value of half of the crack length of CP was increased with an increase in indentation load and loading time, reaching a maximum (530 microns) at 20kgf of indentation load and 30s of loading time. 3) KIC of CP reached the maximum value (2.78MNm-3/2) at 5kgf of indentation load and 5s of loading time, and the minimum (1.52MNm-3/2) at 20kgf of indentation load and 30s of loading time. 4) Optimal experimental conditions for KIC of CP determined by indentation method were 5kgf or 10kgf of indentation load and 15s of loading time. 5) KIC values (MNm-3/2) determined at 5kgf of indentation load and 15s of loading time for CP, AP, MIS and MI were 2.27, 0.95, 1.82 and 1.81, respectively. 6) The course of cracks due to indentation force showed a linear pattern of intra-granular fracture. 7) The cracks were revealed to show median cracks by fractography.

Ceramics↗
PubMed1990

Morphologic changes in cerebral arteries after subarachnoid hemorrhage.

The premise of this article is that morphologic changes observed in cerebral arteries after subarachnoid hemorrhage play an important role in the pathogenesis of associated ischemic deficits observed in this disorder. Secondly, the arteriopathic response of cerebral arteries to subarachnoid blood is similar in many respects to that observed in systemic vessels under various pathologic conditions, and common pathogenic mechanisms may exist. The data supporting these premises may be summarized as follows: 1. Morphologic changes in human and animal cerebral arteries after subarachnoid hemorrhage are temporally associated with angiographic and clinically significant vasospasm. 2. Profound morphologic changes in cerebral arteries after subarachnoid hemorrhage do not contribute to structural narrowing of the lumen through increases in vessel wall mass. Nevertheless, structural changes may act in concert with contractile mechanisms to alter normal physiologic responses and maintain a narrowed lumen. 3. The agent responsible for arterial narrowing and morphologic changes in cerebral arteries after subarachnoid hemorrhage is contained in the erythrocyte component of whole blood and is most likely hemoglobin. 4. The volume and duration of exposure of subarachnoid blood to the artery appears to be significant in the development of the angiopathic response. 5. Ultrastructural abnormalities in systemic vessels associated with hypertension, atherogenesis, and endothelial damage are similar in many respects to those seen after subarachnoid hemorrhage.

Animals↗
PubMed1990

[A case of autoimmune hemolytic anemia and bullous pemphigoid-like skin lesion combined with idiopathic thrombocytopenic purpura].

A case of autoimmune hemolytic anemia (AIHA) and bullous pemphigoid (BP)-like skin lesion combined with Idiopathic thrombocytopenic purpura (ITP) is reported. A 25-years-old male, who had been diagnosed as ITP and treated at another hospital, was admitted in this hospital recently complaining of disseminated bullous-vesicular eruptions on the whole body and autoimmune hemolytic anemia. Examinations, disclosed that RBC was 364 X 10(4)/microliters, reticulocyte 40, platelet 3000/microliters, direct and indirect Coombs test positive, and platelet Coombs consumption test was positive leading to the diagnosis of AIHA and ITP, known as "Evans syndrome." Vesicular biopsy-findings and immunofluorescence study showed suspicion of BP, but clinical course and blister was not improved though the administration of prednisolone was performed. Reports of cases of BP complicated by Evans syndrome are very few. AIHA, ITP and BP are considered to have autoimmune disorders and their pathogenetic mechanism are discussed. This patient consulted another hospital one year later, when we heard that skin eruptions already had disappeared.

Adult↗
PubMed1990

[The use of Pugh score to evaluate the prognostic and therapeutic influence of drinking in patients with decompensated liver cirrhosis].

The aim of this study is to evaluate the clinical usefulness of Pugh score in the prognosis of the patients (pts.) with decompensated liver cirrhosis (DLC). To determine the influence of heavy drinking with respect to the prognosis of DLC patients, 128 cases of DLC were divided into two groups including the 31 heavy drinker group (Group A) and 97 non-alcoholic group (Group B). At the time of admission, the both groups showed similar Pugh score. However, after initial two hospitalized weeks, Group A started to show significantly lower points of Pugh score than that of in Group B. Fifteen pts. (48%) in Group A and 55 pts. (57%) in Group B had greater than 9 in Pugh score at the time of admission. In Group A, 10 of 15 pts. declined the scores after initial two weeks and 9 of them lived more than one year after admission. In contrast, none of those 55 pts. in Group B declined their Pugh score after admission and 45 of them died within one year. It was concluded that Pugh score was extremely useful to evaluate the prognosis of DLC pts., and DLC pts. who had greater than 9 Pugh score were seemed to be critical. It was suggested that DLC pts. due to heavy drinking tend to improve Pugh score comparing to no alcoholic DLC pts.

Adult↗
PubMed1990

[A case of unresectable pancreatic cancer that responded to UFT chemotherapy].

A 77-year-old patient with an unresectable pancreatic cancer was treated with a combination chemotherapy of UFT (600 mg/day, p.o.) and Lentinan (2 mg/week, i.v.). After three and a half months, a partial response (PR) was achieved, based on the criteria of Koyama, Saito, et al. The findings of the follow up CT scans suggested that 600 mg/day of UFT, rather than 300 mg/day, was effective as a chemotherapeutic agent. Although transient thrombocytopenia (62,000/mm2) and eruption were observed during this therapy, no serious side effects were experienced. After eighteen months of this chemotherapy, the patient has not succumbed and manifests a good quality of life.

Adenocarcinoma↗
PubMed1990

[A case of intracranial hypoglossal neurinoma with no preoperative hypoglossal nerve palsy].

A case of intracranial hypoglossal neurinoma without hypoglossal nerve palsy is reported. A 43-year-old housewife was admitted to our hospital with vertigo and left occipital headache. Neurologically, no cranial nerve deficits were present. CT scan and cerebral angiography showed a mass in the lower left posterior fossa. MRI also revealed a well circumscribed extra-axial mass compressing brain stem and cerebellum to the right. Left suboccipital craniotomy was performed and the tumor was removed subtotally. From the operative findings, the 8th to 11th cranial nerves were not related to the tumor, however, the origin of the tumor was not confirmed. The histology showed Antoni A type neurinoma mixed partially with Antoni B type. After the operation, the tongue deviation appeared to the left, but no other cranial nerve deficit was noticed. Post-operative neuroradiological reexaminations defined slight enlargement of the hypoglossal canal. Then, we concluded that the origin of the tumor must have been the hypoglossal nerve. Most intracranial hypoglossal neurinoma grow in the hypoglossal canal followed by enlargement or erosion of the hypoglossal canal. The author thought that this case suggests that this hypoglossal neurinoma originated from a few rootlets of hypoglossal nerve and grew mainly between the medulla and the hypoglossal canal.

Adult↗
PubMed1990

[A case of hypertrophic cardiomyopathy with right ventricular outflow obstruction manifested during three-year follow-up study].

A case is reported of a 55-year-old female with idiopathic hypertrophic cardiomyopathy, which was accompanied with outflow obstruction in the right ventricle developed during the previous 3 years without lesion of the left ventricle. In 1984, she was admitted to our hospital to be examined for cardiac murmurs and abnormal electrocardiogram including ST depression and inverted T. The findings of echocardiography and cardiac catheterization revealed non-obstructive hypertrophic cardiomyopathy. She had been treated with sympathetic beta-blockade and calcium antagonist for 3 years until she complained of dyspnea on exertion, and she was readmitted to our hospital in 1987. Echocardiographic findings showed protrusion of the ventricular septum toward the right ventricle and systolic turbulent flow along the right ventricular outflow tract (by pulsed Doppler technique). A pressure gradient of 20 mmHg across the protrusion was detected by the examination of the cardiac catheter. However, neither protrusion nor pressure gradient was observed in the left ventricular outflow tract as well as that in 1984. Idiopathic hypertrophic cardiomyopathy has been described as involving both ventricles, and outflow obstruction is the usual hemodynamic finding in the left ventricle. However, right ventricular outflow obstruction is the usual hemodynamic finding in the left ventricle. However, right ventricular outflow obstruction with the left ventricular outflow tract intact has been very rare. In addition, in this case, the change of hemodynamic characteristics from non-obstructive to obstructive hypertrophic cardiomyopathy, and the development of these changes only in the right ventricle were observed during the last 3 years.

Cardiomyopathy, Hypertrophic↗