Search PubMed⌕ Search

Biomedical subjects

M Usui

Publications and source records attributed to M Usui.

At least 73 records · Page 4Linked to original sources
PubMed2000

Resection arthrodesis of the knee with a vascularised fibular graft. Medium- to long-term results.

We present the results in 12 patients of arthrodesis of the knee using a vascularised fibular graft after resection of a malignant bone tumour. At a mean follow-up of 95 months (60 to 178) all patients were free from disease although 11 had had at least one complication, with stress fracture of the graft in five patients, nonunion in two and deep infection requiring above-knee amputation in one. Despite the high rate of complications, satisfactory results can be obtained using this technique. Careful preoperative counselling is required.

Adolescent↗
PubMed2000

Reconstruction and limb salvage using a free vascularised fibular graft for periacetabular malignant bone tumours.

We treated four patients with periacetabular malignant tumours by pelvic reconstruction with a free vascularised fibular graft after resection of the tumour. The mean follow-up period was 32 months (9 to 39). The diagnosis was chondrosarcoma in three patients and osteosarcoma in one. In two patients total resection of the hemipelvis was required and in the other two less, but still massive, resection was undertaken. All were treated with an immediate free vascularised fibular graft which included arthrodesis of the hip and reconstruction of the pelvic ring. One patient died. The other three have remained free from recurrence. Solid union of the graft was achieved between four and 14 months after surgery. Shortening of the involved limbs was less than 2 cm. The patients had no pain and were independent walkers without external support. Emotional acceptance was satisfactory. Our results suggest that reconstruction with the use of a free vascularised graft is an alternative to other types of reconstructive procedure after resection of periacetabular tumours.

Acetabulum↗
PubMed2000

ACAID induced by allogeneic corneal tissue promotes subsequent survival of orthotopic corneal grafts.

PURPOSE: To determine whether immune deviation is induced by allogeneic corneal tissue implanted in the anterior chamber and whether survival of subsequent orthotopic corneal allografts is thereby enhanced. METHODS: Corneal tissue from C57BL/6 mice was implanted in the anterior chamber of eyes of BALB/c mice. The fate of these implants was assessed histologically, and the donor-specific immune response of recipient mice was tested for donor-specific delayed hypersensitivity and the capacity to accept or reject C57BL/6 corneas grafted orthotopically into the fellow eye. RESULTS: C57BL/6 cornea implants in the anterior chamber failed to induce donor-specific delayed hypersensitivity but impaired donor-specific delayed hypersensitivity in a proportion of recipients with implants in place for 2 weeks. Mice with donor-specific delayed hypersensitivity rejected the intraocular implants. Mice bearing C57BL/6 cornea implants in the anterior chamber for 2 (but not 4) weeks accepted the C57BL/6 corneas grafted orthotopically into the fellow eye at a high rate and with few rejection reactions. CONCLUSIONS: Implantation of allogeneic corneal tissue in the anterior chamber of the eye has the transient capacity to alter the recipient alloimmune response in a manner that promotes survival of subsequent orthotopic corneal allografts.

Animals↗
PubMed2000

[Uveitis associated with zoster sine herpete. Diagnosis and clinical findings].

PURPOSE: Zoster sine herpete (ZSH) causes solely neurologic symptoms without the eruption that is evident in herpes zoster ophthalmicus. It is occasionally complicated by acute granulomatous uveitis. We examined patients suspected of ZSH for detection of the varicella-zoster virus (VZV) genome, and discussed its clinical appearance. MATERIALS AND METHODS: Nine patients were presumed to have ZSH. All manifested acute granulomatous iridocyclitis and high intraocular pressure without eruption. A polymerase chain reaction (PCR) analysis of the aqueous humor was performed. RESULTS: Five patients were positive for VZV DNA. They showed mutton-fat keratic precipitates and high intraocular pressure in the early stage. Pigmentation in the anterior chamber angle, pigmented keratic precipitates, and finally sectoral iris atrophy were observed in the recovery stage. These clinical findings were common to ZSH. CONCLUSIONS: The ocular lesions in ZSH were shown to have distinctive characteristics, and PCR is useful to determine etiological agents in the early stage of disease.

Adult↗
PubMed2000

[Molecular biological analysis of retinal and streptococcal heat-shock protein 60].

PURPOSE: The observation of recurrent oral aphtha preceding ocular inflammation in patients with Behçet's disease suggests a role of oral Streptococcus in the etiology of this disease. Heat-treated Streptococcus antigen can induce ocular inflammation or systemic symptoms in Behçet's disease patients. Furthermore, the presence of an autoantibody against retinal heat-shock protein 60 (HSP 60) has been detected in the sera of these patients. Injection of extracted retinal HSP 60 also induces experimental uveitis in treated rats. The characteristics of retinal HSP 60 and HSP 60 from S. pyogenes were evaluated using a molecular biological approach. METHODS: The gene encoding HSP 60 was isolated by polymerase chain reaction (PCR) from a bovine retinal cDNA library and from S. pyogenes DNA. The DNA sequence of the HSP 60 coding region was determined, and the amino acid sequences of the encoded proteins were predicted from the DNA sequence. The synthetic peptide (50 nmol) was emulsified with Freund's complete adjuvant and injected into rats. RESULTS: Comparison of the amino acid sequences of Streptococcal and bovine retinal HSP 60 revealed about 200 residue regions with 47% homology. Experimental uveitis was mainly induced in rats inoculated with retinal HSP 60-derived peptide or Streptococcus HSP 60-derived peptide that is equivalent to residues 245-259 of human HSP 65. DISCUSSION: The retinal and Streptococcal HSP 60 amino acid composition is thought to be important and useful for investigating the mechanisms involved in the induction of Behçet's disease.

Animals↗
PubMed2000

[Typing of herpes simplex virus in patients with uveitis].

AIM: To examine the type of herpes simplex virus (HSV) in cases with uveitis. MATERIALS AND METHODS: Intraocular fluid specimens obtained from 3 cases with herpetic iridocyclitis and 6 cases with acute retinal necrosis (ARN) were examined by polymerase chain reaction (PCR). HSV typing was performed by the restriction patterns of the PCR products. Serum samples obtained from these cases and 33 cases with uveitis were examined by neutralization test (NT) for the availability of the typing of HSV. RESULTS: The restriction patterns of the PCR products amplified from 3 specimens of iridocyclitis revealed HSV type 1 DNA. HSV type 2 DNA was identified in 5 of 6 cases of ARN and HSV type 1 DNA was found in only one case. The results of serum NT titers correlated with the typing of the amplicons. CONCLUSIONS: In the cases studied, HSV type 1 was the dominant etiological agent in herpetic iridocyclitis, while HSV type 2 played a similar role in HSV-associated ARN. The examination of the serum NT may be helpful for the identification of the etiological types of HSV in patients with uveitis.

Adult↗
PubMed1999

Circadian variation of idiopathic ventricular tachycardia originating from right ventricular outflow tract.

We determined circadian variation of isolated ventricular premature complexes (VPCs), 2 to 4 consecutive VPCs, and ventricular tachycardia (5 consecutive VPCs) originating from the right ventricular outflow tract in patients without apparent structural heart diseases. There was apparent circadian variation with 2 prominent peaks for these ventricular arrhythmias, and blockade abolished ventricular tachycardia and attenuated the circadian variation of consecutive VPCs.

Adult↗
PubMed1999

Neurosteroid modulation of dendrodendritic inhibition in the mouse olfactory bulb.

The present report describes neurosteroid modulation of olfactory bulb function by examining the effects of intrabulbar infusion of dehydroepiandrosterone sulfate (DHEAS), a neurohormone discovered in rat brain, on field potentials in the granule cell layer evoked by paired-pulse stimulation of the mouse lateral olfactory tract. Infusion of DHEAS (5 nmol) significantly decreased the test response without affecting the conditioning response. As a consequence, DHEAS selectively potentiated paired-pulse depression, which is believed to be due to granule cell-mediated inhibition of the mitral/tufted cells. The granule-to-mitral/tufted dendrodendritic synapse is GABAergic. Taken together, these results suggest that DHEAS potentiates the GABAergic dendrodendritic inhibition exerted by the granule cells on the mitral/tufted cells.

Analysis of Variance↗
PubMed1999

Endogenous nitric oxide synthase inhibitor: a novel marker of atherosclerosis.

BACKGROUND: Exposure to risk factors such as hypertension or hypercholesterolemia decreases the bioavailability of endothelium-derived nitric oxide (NO) and impairs endothelium-dependent vasodilation. Recently, a circulating endogenous NO synthase inhibitor, asymmetric dimethylarginine (ADMA), has been detected in human plasma. The purpose of this study was to examine the relationship between plasma ADMA and atherosclerosis in humans. METHODS AND RESULTS: Subjects (n=116; age, 52+/-1 years; male:female ratio, 100:16) underwent a complete history and physical examination, determination of serum chemistries and ADMA levels, and duplex scanning of the carotid arteries. These individuals had no symptoms of coronary or peripheral artery disease and were taking no medications. Univariate and multivariate analyses revealed that plasma levels of ADMA were positively correlated with age (P<0.0001), mean arterial pressure (P<0.0001), and Sigma glucose (an index of glucose tolerance) (P=0.0006). Most intriguingly, stepwise regression analysis revealed that plasma ADMA levels were significantly correlated to the intima-media thickness of the carotid artery (as measured by high-resolution ultrasonography). CONCLUSIONS: This study reveals that plasma ADMA levels are positively correlated with risk factors for atherosclerosis. Furthermore, plasma ADMA level is significantly correlated with carotid intima-media thickness. Our results suggest that this endogenous antagonist of NO synthase may be a marker of atherosclerosis.

Adult↗
PubMed1999

The role of costimulatory molecules B7-1 and B7-2 in mice with experimental autoimmune uveoretinitis.

BACKGROUND: Onset of experimental autoimmune uveoretinitis (EAU) is believed to involve a CD4-positive type 1 T helper cell (Th1) immune response, with inhibition involving a Th2 immune response. Development of Th1 and Th2 responses involves the participation of the costimulatory molecules B7-1 and B7-2, respectively. The purpose of this study was to investigate the role of B7-1 and B7-2 in the EAU model in mice. METHODS: B10.A mice were immunized with interphotoreceptor retinoid-binding protein (IRBP) and given daily intraperitoneal injections of either phosphate-buffered saline (control), mouse monoclonal antibody (mAb) to B7-1, mAb to B7-2, or mAb to both B7-1 and B7-2. Eyes were evaluated by histopathological criteria and cytokines were assayed in culture medium of IRBP-stimulated lymphocytes. Cellular immune responses were measured by cell proliferation assay under IRBP stimulation. RESULTS: Rates of EAU onset were 5/10 (50%) for control mice, 1/9 (11%) for mice treated with anti-B7-1 mAb, 5/6 (83%) for mice treated with anti-B7-2 mAb, and 2/6 (33%) for mice treated with both anti-B7-1 and anti-B7-2 mAb. Mean histopathological severity scores were 2. 4+/-0.8, 1.0+/-0, 2.6+/-1.0, and 1.0+/-0, respectively. Production of IL-5 was significantly increased in mice treated with anti-B7-1 mAb, while IFN-gamma was increased in mice treated with anti-B7-2 mAb. Spleen cell proliferation was significantly reduced in mice treated with anti-B7-1 mAb. CONCLUSIONS: These results suggest that the costimulatory molecules B7-1 and B7-2, via their influence on generating Th1 and Th2 immune responses, play an important role in the clinical outcome of EAU in mice immunized with IRBP.

Animals↗
PubMed1999

Effect of pancreatic juice reflux into biliary tract on N-nitrosobis(2-oxopropyl)amine (BOP)-induced biliary carcinogenesis in Syrian hamsters.

To elucidate the possible role of pancreatic juice reflux into the biliary tract in promoting the development of biliary carcinoma, Syrian hamsters were subjected to cholecystoduodenostomy and ligation of the distal end of the common duct and then subcutaneously injected with N-nitrosobis(2-oxopropyl)amine (BOP) (experimental group). The incidences of gallbladder carcinoma and extrahepatic bile duct carcinoma in the experimental group was significantly higher than in the sham-operated group (P < 0.01, P < 0.05). The proliferating cell nuclear antigen (PCNA) labeling indices of both regions gradually increased with time, and were significantly higher in the experimental group at weeks 9 and 16 than in the sham-operated group at the same time. Trypsin and phospholipase A2 (PLA2) activities in bile and tissue levels of superoxide dismutase (SOD) in the gallbladder and extrahepatic bile ducts were higher in the experimental group than in the sham-operated group. These findings suggest that the carcinogenic effect of BOP was enhanced in biliary epithelium that had proliferated in response to and/or had been injured by activated pancreatic enzymes refluxing into the biliary tract and then increased free radical activity, leading to a high frequency of carcinoma development in the biliary tract.

Animals↗
PubMed1999

Role of the N-terminal region of ribosomal protein S7 in its interaction with 16S rRNA which binds to the concavity formed by the beta-ribbon arm and the alpha-helix.

The ribosomal protein S7, a primary 16S rRNA-binding protein, plays an essential role in stabilizing the 3' major domain of 16S rRNA and also in feedback regulation of the str operon, as a translational repressor. We examined amino acid residues in ribosomal protein S7 from Bacillus stearothermophilus (BstS7) that are essential for 16S rRNA binding. Truncation of the N-terminal 10 residues of BstS7 abolished its binding to 16S rRNA, whereas removal of the C-terminal eight residues had no effect on the binding activity. Subsequently, we used site-directed mutagenesis to identify essential basic residues in the N-terminal region for 16S rRNA binding. Mutation of Arg3 and Lys8 significantly weakened the binding activity, and a smaller decrease in binding activity was observed with Arg2 and Arg9 mutations. These observations indicate that N-terminal basic residues, especially Arg3 and Lys8, play a crucial role as positively charged recognition groups for the negatively charged phosphate backbone of 16S rRNA. In addition, the mutagenesis study showed that Arg75, Arg78, Arg94, and Arg101, which are located in a concavity formed by the beta-ribbon arm and the alpha-helix (alpha4), individually make only a small contribution to 16S rRNA binding, but together probably form a positively charged binding site for 16S rRNA. With regard to aromatic residues, Tyr84 on the tip of the beta-ribbon arm was found to be involved in 16S rRNA binding, whereas the conserved aromatic residues Trp102 and Tyr106 in the concavity had little effect. We then probed the 16S rRNA-binding site(s) for the N-terminal region of S7 with iron tethered to the mutant of BstS7 containing a single cysteine residue at position 4. The N-terminal region of S7 is placed in close proximity to helix 43 in the 16S rRNA. Probing also revealed additional cleavages between nucleotides 1397 and 1438, near the P-site region in 16S rRNA. This finding is consistent with a three-dimensional model of 16S rRNA that shows close proximity of helix 43 to the P-site during three-dimensional folding.

Arginine↗
PubMed1999

Behçet's disease and antibody titers to various heat-shock protein 60s.

It has been suggested that the 65 kDa heat-shock protein (HSP) of Streptococcus in recurrent aphthae within the oral cavity may be involved in the uveoretinitis of Behçet's disease, possibly through sensitization of the immune system. To investigate this possibility, we examined serum antibody titers for various members of the 60 kDa family of HSPs and their implications with regard to a role for HSP60s in Behçet's disease. We isolated HSP60 of Streptococcus pyogenes from the margin of oral aphthae in one Behçet's disease patient with severe uveoretinitis and the HSP60s of Yersinia enterocolitica, retinoblastoma cell line clone Y79, and bovine retinal extract and investigated the reaction of each of these HSP60s with 100-fold diluted serum samples from 20 Behçet's disease patients using anti-HSP60 antibody titers determined by ELISA. The anti- Streptococcus HSP60 antibody and anti-retinal HSP60 antibody titers of the 100-fold diluted serum samples from the Behçet's disease patients were both significantly higher than those of similarly diluted serum samples from healthy donors. The results of the ELISA antibody titer assay showed that, although the various HSP60s share a common basic antigenicity, they differed in reactivity to the anti-HSP60 antibodies in the sera of the Behçet's disease patients. The results indicate that subtle but significant differences exist in the antigenicity of the various HSP60s tested, all of which share a common basic antigenicity and are of approximately the same molecular weight, and suggest that an immuno-cross-reaction between retinal and streptococcal HSPs and a related autoimmune response may be involved in the development of Behçet's disease.

Adult↗
PubMed1999

ST segment elevation in the right precordial leads induced with class IC antiarrhythmic drugs: insight into the mechanism of Brugada syndrome.

We evaluated two patients without previous episodes of syncope who showed characteristic ECG changes similar to Brugada syndrome following administration of Class IC drugs, flecainide and pilsicainide, but not following Class IA drugs. Patient 1 had frequent episodes of paroxysmal atrial fibrillation resistant to Class IA drugs. After treatment with flecainide, the ECG showed a marked ST elevation in leads V2 and V3, and the coved-type configuration of ST segment in lead V2. A signal-averaged ECG showed late potentials that became more prominent after flecainide. Pilsicainide, a Class IC drug, induced the same ST segment elevation as flecainide, but procainamide did not. Patient 2 also had frequent episodes of paroxysmal atrial fibrillation. Pilsicainide changed atrial fibrillation to atrial flutter with 2:1 ventricular response, and the ECG showed right bundle branch block and a marked coved-type ST elevation in leads V1 and V2. After termination of atrial flutter, ST segment elevation in leads V1 and V2 continued. In this patient, procainamide and quinidine did not induce this type of ECG change. In conclusion, strong Na channel blocking drugs induce ST segment elevation similar to Brugada syndrome even in patients without any history of syncope or ventricular fibrillation.

Anti-Arrhythmia Agents↗
PubMed1999

DISI Deformity and Post-Operative Symptoms of Scaphoid Non-Union.

The correlation between the residual dorsal intercalated segmental instability (DISI) deformity and symptoms of the wrist was investigated in 20 patients with healed scaphoid non-union who had open reduction and bone grafting. In seven patients, inlay corticocancellous bone grafting (modified Russe procedure) was performed. In four of the seven patients, an additional Herbert bone screw was used for internal fixation. The remaining 13 patients were treated with open reduction, anterior bone grafting, and internal fixation with Herbert bone screw. Average duration of follow-up period after operation was 20 months (range, 6 to 57 months). The average extension-flexion arc of the injured wrists was 129 degrees, which was 31 degrees less than that of the uninjured wrists. The average grip strength of the injured wrists was 89% of that of the uninjured wrist. Before the operation, all 20 patients were symptomatic and complained of wrist pains. Post-operatively, three patients experienced mild pains and only one complained of moderate wrist pains. Post-operative radiolunate angle ranged from 0 degrees to 34 degrees (average 10 degrees ). DISI deformity remained uncorrected in eight patients. Post-operative symptoms were compared amongst the eight patients who had DISI deformity and 12 patients who had no deformity. There was no significant difference in range of motion, grip strength, and incidence of pain between these two groups of patients. The presence of DISI deformity after bone grafting for a symptomatic scaphoid non-union was not predictive of post-operative symptoms of the wrist.

Journal Article↗