Search PubMed⌕ Search

Biomedical subjects

M Usui

Publications and source records attributed to M Usui.

At least 19 recordsLinked to original sources
PubMed1992

Usefulness of a novel monoclonal antibody against human osteocalcin in immunohistochemical diagnosis.

A novel monoclonal antibody against human osteocalcin, recently established in our laboratory, was shown by immunoblotting and immunohistochemistry to react specifically with human osteoblasts. In the present study, the antibody was applied to the immunohistochemical diagnosis of human bone tumours, especially osteoblastic tumours. The antibody reacted with all 27 osteosarcomas. No positive reaction was found either in chondrosarcoma, giant cell tumours of bone, soft tissue tumours or epithelial tumours. A positive reaction was found preferentially in the cytoplasm of most of the osteosarcoma cells, but not in the extracellular matrix. Since the antibody reacted with formalin-fixed and paraffin-embedded tissues, it will be a useful tool for routine immunohistochemical diagnosis of osteoblastic lesions.

Animals↗
PubMed1992

Cerebral metastasis of malignant cardiac myxoma.

A rare case of bona fide cerebral metastasis of malignant cardiac myxoma is presented. The parenchymal brain tumor of a 32-year-old woman with a history of surgical operations on cardiac myxoma and jejunal leiomyosarcoma was surgically extirpated. The initial pathological diagnosis was metastatic sarcoma. Ten months later, an occlusion of bilateral carotid arteries occurred that was due to tumor emboli. The postmortem examination revealed an unusually rapid recurrence of the cardiac tumor containing sarcomatous components that were histologically identical to the tumors of the brain and the jejunum and the emboli of the cerebral vessels. Hence it was deduced that they all originated in the primary malignant cardiac myxoma.

Adult↗
PubMed1992

Role of anisotropy in determining the selective action of antiarrhythmics in atrial flutter in the dog.

OBJECTIVE: The aim was to clarify the electrophysiological and anatomical features of the preferential site of action of antiarrhythmic drugs in the re-entrant circuit of canine atrial flutter. METHODS: Electrophysiological and anatomical findings were correlated in 17 anaesthetised adult mongrel dogs with atrial flutter associated with an intercaval anatomical obstacle, before and after intravenous administration of disopyramide (2 mg.kg-1) and flecainide (2 mg.kg-1). RESULTS: Before drug injection, a rate dependent prolongation of conduction time occurred in the low right atrium where the conduction was slow during atrial flutter. Disopyramide (n = 8 dogs) and flecainide (n = 9 dogs) terminated atrial flutter, with conduction block occurring in this slow conduction area in the low right atrium. Although the degree of drug induced prolongation of refractoriness in this particular area was similar to those in other areas of the right atrium, conduction was depressed to a greater extent in this region. Anatomical study revealed that a thick pectinate muscle that branched from the crista or crista terminalis itself ran perpendicular to the wavefront of the pacing impulse and atrial flutter in this slow conduction area. CONCLUSIONS: These data indicated that slow conduction might be attributed, at least in part, to anisotropic conduction over the thick muscle bundle in the low right atrium, and that antiarrhythmic drugs preferentially produced conduction block in this area. Anisotropic conduction in the low right arium is an anatomical substrate for slow conduction in the re-entrant circuit and for the site preference of antiarrhythmic drugs in the present canine model.

Animals↗
PubMed1992

Antigenic analyses of Sugi basic protein by monoclonal antibodies: I. Distribution and characterization of B-cell-tropic epitopes of Cry j I molecules.

Using 23 monoclonal antibodies raised against Sugi basic protein (SBP, major allergen of Japanese cedar pollen), composed of Cry j I and Cry j II, analyses of B-cell-tropic epitopes of Cry j I were performed. The following results were obtained. (1) As far as the mAbs were used, no major cross-reactive determinants were detected between Cry j I and Cry j II molecules. (2) 21 of the 23 mAbs were specific for Cry j I, and the anti-Cry j II mAbs were classified into four groups by their fine specificities, suggesting that Cry j I bears at least four antigenic determinant regions. (3) Cry j I molecules were found to take a monomeric form in solution and to display no repeating antigenic epitopes on their surfaces. (4) Some of the determinants seemed to be located in the interior of a Cry j I molecule, and when the Ag is coated on a plastic plate, the determinants become exposed on its surface. (5) Binding of human IgE antibodies to Cry j I and Cry j II was blocked by some of the obtained mAbs, suggesting that these epitopes recognized by the mAbs might have an important role in human allergic response against the cedar pollen.

Allergens↗
PubMed1992

Antigenic analyses of Sugi basic protein by monoclonal antibodies: II. Detection of immunoreactive fragments in enzyme-cleaved Cry j I.

The 4 anti-Cry j I mAbs showing an epitope specificity different from each other, 046, 029, 026 and 027, were selected to analyze the structure of the antigenic determinant for each mAb on a Cry j I molecule. Immunoreactive fragments in enzyme-cleaved Cry j I were detected by means of the adsorption on the mAb column and of the binding to the mAbs on Elisa. The mAb 026 was found to be reactive to the fragments containing a Cry j I N-terminal region obtained by V8 protease or pepsin digestion, but not to those by lysylendopeptidase digestion. The mAb 027 was found to be capable of binding to the fragments containing a linear structure of Asn-Ala-Gly-Val-Leu-Thr-Cys-Ser-Leu-Ser-Lys, which were generated by V8 protease, lysylendopeptidase or pepsin digestion. Furthermore, the synthetic peptide Asn-Ala-Gly-Val-Leu-Thr-Cys-Ser- Leu-Ser-Lys-Arg could bind to 027, but not to 026, and could inhibit the binding of 027 to Cry j I or to its immunoreactive fragments. No fragments capable of reacting to the mAbs 046 and 029 could be found in this study, suggesting that 046 and 029 recognize a conformationally constituted epitope of Cry j I molecule which is destroyed by enzymatic cleavage. The epitope recognized by the mAbs 027 or 026 was found to be located in conformationally hidden parts of the molecule which was exposed to react to the mAbs only after the physicochemical or enzymatic treatment.

Allergens↗
PubMed1992

[The onset mechanism of experimental autoimmune uveoretinitis induced by interphotoreceptor retinoid-binding protein].

In order to analyze the onset mechanism of experimental autoimmune uveoretinitis (EAU), two experimental models were used; one was EAU induced by one injection of purified bovine interphotoreceptor retinoid-binding protein (IRBP) with complete Freund's adjuvant in Lewis rat, and the other was an IRBP-induced autoimmune uveoretinitis that occurred spontaneously in nude (nu/nu) mice at 4 weeks of age reconstituted by the grafting of rat embryonic thymus (TG nude mouse). EAU develops when the IRBP-reactive lymphocytes in the regional lymph-nodes are activated. Activation begins when the T lymphocyte recognizes the peptide for the epitope bound to a major histocompatibility complex (MHC) molecule in the antigen-presenting cell by way of the T-cell receptor (TCR). In EAU, ten peptide residues p1182-1191 of the IRBP amino acid sequence, were revealed to be sufficiently capable of lymphocyte activation for EAU, and it was also shown that amino acid positions 1182W (tryptophane), 1185G (glycine), 1186V (valine) and 1188P (proline) of IRBP play important roles as the epitopes or agretopes in developing EAU. On the other hand, two amino acids of IRBP, amino acid positions 1182W (tryptophane) and 1194P (proline) were shown to be the agretopes inducing autoimmune uveoretinitis in the TG nude mouse. A study of the variable region of the TCR with a residual p1182-1194 specific T-cell line from the TG nude mouse revealed that as many as 96% utilized the T-cell receptor V beta 6 gene and that the peptide-MHC molecule complex was recognized by restricted receptors. Adhesion molecules such as ICAM-1 and LFA-1 were also found to play an important role as cofactors in activation of lymphocytes in the antigen-recognition process of EAU. Uveoretinitis seemed to result from an immune reaction in the eye occurring when the T lymphocyte arrives there, activating the immunological process. ICAM-1 and LFA-1 were also found to be involved in the infiltration process of inflammatory cells: our immunohistological examination revealed that ICAM-1 was present in the retinal pigment epithelium and epithelium of the ciliary body composing the blood-ocular barrier. In contrast, LFA-1 was expressed in the infiltrating cells. Finally, the tolerance of IRBP was discussed and it was experimentally demonstrated that the absence of IRBP-induced uveoretinitis in human beings and certain experimental animals resulted from endogenous IRBP serving as a tolerogen; we assumed that the breakdown of this self-tolerance would induce EAU due to thymic dysfunction or IRBP antigen injection.

Amino Acid Sequence↗
PubMed1992

[Preliminary clinical trial of intrathecal rt-PA (TD-2061) for the prevention of cerebral vasospasm in patients with aneurysmal subarachnoid hemorrhage].

The results of preliminary clinical trial (a multicenter, open-label, dose escalation study) of intrathecal recombinant tissue plasminogen activator (rt-PA) for the prevention of cerebral vasospasm were reported. Seventeen patients admitted within 48 hours of subarachnoid hemorrhage (SAH) were enrolled in this study. Patients ranged from 42 to 69 years of age. All cases enrolled were classified in clinical grade II, III or IV according to the classification of Hunt and Kosnik and in group 3 or 4 according to Fisher's CT grading scale. Surgery for clipping the aneurysms were performed and a small silicone catheter was left in the subarachnoid space. Twenty four hours after the surgery intrathecal bolus infusion of rt-PA was started through the silicone catheter at 6-hour intervals for 3 days. Patients were divided into 4 groups based on the dosage of rt-PA for each infusion. The dosage of rt-PA for each infusion and a number of cases in each group was as follows; 25 KIU in 4 cases, 75 KIU in 6 cases, 200 KIU in 4 cases and 600 KIU in 3 cases. There was no significant difference in the clearance of subarachnoid clots between four groups. However, the occurrence of both symptomatic and angiographic vasospasm was less in the 75 KIU group than in other three groups. Intracranial bleeding complications were noted in 4 patients (1/6 in the 75 KIU group, 2/4 in the 200 KIU group and 1/3 in the 600 KIU group). Serial coagulation studies demonstrated no evidence of systemic fibrinolysis. Disorientation was noted in 2 out of 3 patients of the 600 KIU group.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

A new method for estimating preexcitation index without extrastimulus technique and its usefulness in determining the mechanism of supraventricular tachycardia.

The preexcitation index has been shown to be useful in determining the mechanism of paroxysmal supraventricular tachycardia (SVT) and the site of the accessory pathway in atrioventricular (AV) reentrant tachycardia. To test whether a preexcitation index could be computed analytically instead of by scanning the whole SVT cycle with extrastimuli, 19 patients with SVT were studied. The new index was computed using the following formula: (AV conduction time during SVT) + (ventriculoatrial conduction time during ventricular pacing at the SVT cycle length) - (SVT cycle length). There was a strong correlation between the preexcitation index determined by the extrastimulus technique and the new index in 15 patients in whom the preexcitation index could be determined (r = 0.99, p less than 0.01). The value on the new index was greater than 90 ms only in patients with dual AV nodal pathways. In the 4 patients in whom the preexcitation index could not be determined by the extrastimulus technique, the new index could differentiate AV reentrant tachycardia (index for 2 patients, 60 and 60 ms, respectively) from AV nodal reentrant tachycardia (index for 2 patients, 100 and 105 ms, respectively). In conclusion, the new index provided help in determining the mechanism of SVT, even when retrograde atrial preexcitation by a ventricular extrastimulus did not occur.

Adolescent↗
PubMed1991

Acute effect of percutaneous transluminal mitral commissurotomy on QT interval: possible role of afterload in contraction-excitation feedback.

Percutaneous balloon valvuloplasty for pulmonary or aortic stenosis results in QT prolongation, a finding supporting the presence of contraction-excitation feedback in man. Though afterload reduction alters the QT interval, the effect of changes in preload on ventricular repolarization is yet unknown. To test whether diastolic stretch modified ventricular repolarization, the change in the QT interval was determined in 15 patients who underwent percutaneous transluminal mitral commissurotomy (PTMC) for mitral stenosis. After successful PTMC, the QT interval was prolonged in five, shortened in two, and was unchanged in eight patients, but the mean QT interval in 15 patients did not change (406 +/- 31 msec versus 412 +/- 40 msec, p = NS). However, linear regression analysis revealed a strong correlation between changes in the QT interval and those in systemic vascular resistance (r = -0.83, p less than 0.01). These data indicated that changes in the QT interval after PTMC were small compared with those seen with valvuloplasty for pulmonary or aortic stenosis, and were dependent on afterload but not on preload.

Adult↗
PubMed1991

Immunophenotypic heterogeneity in osteosarcomas.

Eighteen osteosarcomas were studied immunohistochemically. The tumors were classified into the following six histologic subtypes: five osteoblastic, four chondroblastic, four malignant fibrous histiocytoma-like, two telangiectatic, two low-grade central, and one giant cell-rich. Variable amounts of osteocalcin immunoreactivity were found in all tumors. Factor XIIIa-positive cells, which may be of fibrohistiocytic lineage, were present in three tumors of the malignant fibrous histiocytoma-like type, one of the telangiectatic type, one of the low-grade central type, and the tumor of the giant cell-rich type. One tumor of the osteoblastic type showed cytokeratin and epithelial membrane antigen immunoreactivities. The positive reactions for desmin in four tumors, for alpha-smooth muscle actin in 11 tumors, and for type IV collagen in one tumor seemed to indicate myofibroblastic differentiation of some tumor cells. S-100 protein-positive tumor cells were detected not only in all four tumors of the chondroblastic type, but also in three of the osteoblastic type, one of the low-grade central type, and in the tumor of the giant cell-rich type. These immunohistochemical results suggest that osteosarcomas are composed of heterogeneous cell populations, such as those of the osteoblastic, chondroblastic, myofibroblastic, and fibrohistiocytic types, and occasionally also of cells with epithelial features.

Adolescent↗
PubMed1991

Antiarrhythmic drugs preferentially produce conduction block at the area of slow conduction in the re-entrant circuit of canine atrial flutter: comparative study of disopyramide, flecainide, and E-4031.

STUDY OBJECTIVE: The aim was to test whether antiarrhythmic drugs preferentially suppressed conduction in the area of slow conduction in the re-entrant circuit. DESIGN: Intravenous disopyramide [n = 8, plasma concentrations: 1.4 (SEM 0.2) micrograms.ml-1], flecainide [n = 8, 0.6(0.1) micrograms.ml-1], and E-4031, a new class III antiarrhythmic drug [n = 8, 5.6(1.0) ng.ml-1], were investigated for their effects on atrial flutter due to re-entry in dogs with intercaval crush. In three dogs, detailed atrial activation sequence during atrial flutter was determined with a hand held bipolar electrode and an epicardial isochronal map was drawn. EXPERIMENTAL MATERIAL: 24 anaesthetised adult mongrel dogs were used. MEASUREMENTS AND MAIN RESULTS: There was an area of slow conduction during atrial flutter in the low right atrium. Atrial flutter was terminated in all dogs except for one treated with flecainide. In 92% of the dogs, conduction block occurred in the low right atrium in which the area of slow conduction was located. Increase in local conduction time was greater in the area of slow conduction than other parts of the atria (percent ratio to the increase in cycle length of atrial flutter: 63% with disopyramide, 52% with flecainide, and 99% with E-4031). CONCLUSION: These data suggested antiarrhythmic drugs preferentially suppressed conduction at the area of slow conduction in the re-entrant circuit leading to termination of atrial flutter in this canine model, irrespective of electrophysiological effects of antiarrhythmic drugs.

Animals↗
PubMed1991

Effects of pentisomide and E-4031 on canine atrial flutter due to reentry: a comparative study with disopyramide and propafenone.

Effects of new antiarrhythmic drugs, pentisomide [3.5 +/- 0.5 mg/kg intravenously (i.v.) n = 8], and E-4031 (5.6 +/- 1.0 micrograms/kg, n = 8), a class III drug, on atrial flutter (AF) caused by reentry were compared with those of disopyramide (1.6 +/- 0.2 mg/kg, n = 8) and propafenone (2.2 +/- 0.2 mg/kg, n = 8). AF was induced with burst atrial pacing after we made an intercaval crush in anesthetized, open-chest dogs. Termination of AF did not differ among test drugs (8 of 8 with disopyramide, 7 of 8 with propafenone, 6 of 8 with pentisomide, and 8 of 8 with E-4031). Cycle length (CL) of AF was prolonged more with propafenone (57 +/- 10%) and pentisomide (41 +/- 5%) than with E-4031 (12 +/- 3%, p less than 0.05). This was also true for increase in interatrial conduction time determined at a pacing CL of 150 ms. Increase in atrial effective refractory period (ERP) determined at a basic pacing CL of 300 ms did not differ among test drugs. Changes in CL of AF correlated significantly with those in interatrial conduction time (r = 0.84, p less than 0.001), but not with those of ERP (r = 0.10, NS). Reinitiation of AF was significantly greater in propafenone (7 of 7) and pentisomide (5 of 6) groups than in disopyramide (1 of 8) and E-4031 (0 of 8) groups (p less than 0.001). Pentisomide and E-4031 were effective in terminating canine AF due to reentry, as were disopyramide and propafenone. Reinitiation of AF was greater in dogs treated with antiarrhythmic drugs that had more prominent effects on conduction time than on ERP.

Animals↗
PubMed1991

Spontaneous development of autoimmune uveoretinitis in nude mice following reconstitution with embryonic rat thymus.

This paper describes the spontaneous occurrence of an autoimmune uveoretinitis in nude (nu/nu) mice reconstituted when 4 weeks old by the grafting of rat embryonic thymus. The uveoretinitis was characterized histologically by progressive loss of the photoreceptor layer, observed in 4.0, 17.6, 42.9% and 71.4% of such mice at 3, 5, 7 and 12 months of age, respectively. Mice with uveoretinitis were shown to have serum IgG antibody reactive by indirect immunofluorescence with retinal photoreceptors, and with interphotoreceptor retinoid-binding protein (IRBP), but not retinal S-antigen, by immunoblotting and ELISA. A uveoretinitis could be adoptively transferred to syngeneic ungrafted nude mice by splenic CD4+ T cells from diseased animals. This is the first experimental model of a (T cell mediated) autoimmune uveoretinitis which develops spontaneously and which is not dependent upon deliberate sensitization with retinal antigens and adjuvants.

Animals↗
PubMed1991

Treatment of severe intraventricular hemorrhage by intraventricular infusion of urokinase.

Six patients with severe intraventricular hemorrhage were treated with direct intraventricular infusion of urokinase. In each case, hemorrhage extended into all ventricular chambers, and a cast formation and expansion of the third and fourth ventricles were found. Immediately after the therapy was started (within 7 days from onset of symptoms), reduction of intraventricular hematoma volume was observed on computerized tomography. On average, both the third and fourth ventricles became clear on the third day after hemorrhage; there was one exception, a case of ruptured aneurysm. Five of the six patients showed excellent or good outcome, although two developed delayed hydrocephalus. No infection or rebleeding was observed. The outcome in a retrospectively studied group of five patients not treated with urokinase is also reported. The authors conclude that this relatively easy method of treatment will greatly improve the prognosis of severe intraventricular hemorrhage.

Adolescent↗
PubMed1990

Growth of rat-mouse hybridoma cells in immunosuppressed hamsters. An easy and effective method to prepare monoclonal antibodies from heterohybridoma cell lines.

Rat-mouse hybridoma cells producing anti-mouse IgE antibodies were intraperitoneally or subcutaneously inoculated into newborn or suckling hamsters receiving rabbit anti-hamster thymocyte globulin from the day of birth twice a week for at least 3 weeks. The hybridoma cells were found to grow in the abdominal cavity of the hamsters as ascites tumor or in subcutaneous tissue as solid tumor without loss of antibody-secreting activities. For the production of ascites, 2-week-old hamsters were preferable to newborn hamsters. In 3-week-old hamsters, the hybridoma cells could scarcely survive. The antibody titers of the ascites were determined to be 10(5)-10(6) in the ELISA and in the ability to neutralize the skin-sensitizing capacity of mouse IgE antibodies. The rat monoclonal antibodies were easily separated from ascites, serum or cell culture supernatant with affinity chromatography using Affigel protein A-Sepharose and anti-hamster IgG-Sepharose columns. The described method could be efficiently applicable for the proliferation of other hybridomas, such as human-human, human-mouse or hamster-mouse, etc.

Animals↗
PubMed1990

Three cases of EB virus-associated uveitis.

We report our experience with three cases of Epstein-Barr virus (EBV)-associated uveitis. These patients had the following common clinical features: 1) a common cold-like prodrome, 2) bilateral involvement, 3) severe acute anterior uveitis with fibrinous exudate, 4) granulomatous anterior uveitis in the chronic stage, 5) little vitreous inflammation, 6) marked hyperemia and edema of the disc, 7) sunset glow fundus developed very early, 8) a good response to steroids but recurrence was common, 9) good final visual acuity, 10) no systemic changes in the course of the uveitis. High EBV IgG VCA antibody titers were found in the aqueous humor in all three cases (case 1, 1: 40; case 2, 1: 160; case 3, 1: 20). As controls, 37 cataract patients and 14 patients with various types of uveitis were examined for EBV antibodies in the aqueous humor. The result was negative in every case. On the basis of these data, the uveitis in these three patients appears to represent a new clinical entity: uveitis caused by EBV.

Acute Disease↗