Search PubMed⌕ Search

Biomedical subjects

M Usui

Publications and source records attributed to M Usui.

At least 55 records · Page 3Linked to original sources
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 Streptoccus 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 amoino acid composition is thought to be important and useful for investigating the mechanisms involved in the induction of Behçet's disease

Journal Article↗
PubMed2000

Hemodialysis impairs endothelial function via oxidative stress: effects of vitamin E-coated dialyzer.

BACKGROUND: Patients who undergo hemodialysis experience accelerated atherosclerosis and premature death. Recent evidence suggests that endothelial dysfunction proceeds to and exacerbates atherosclerosis. It remains unknown whether hemodialysis per se causes endothelial dysfunction. METHODS AND RESULTS: We evaluated endothelial function estimated by flow-mediated vasodilation during reactive hyperemia using high-resolution ultrasound Doppler echocardiography before and after a single session in patients on maintenance hemodialysis. Several studies have shown that the imbalance between pro-oxidant and antioxidant activities in hemodialyzed patients results in high oxidative stress, which causes lipid peroxidation and endothelial injury. Accordingly, we investigated the effects of antioxidative modification during hemodialysis on endothelial function using a vitamin E-coated cellulose membrane dialyzer. Nonspecific endothelium-independent vasodilation was measured after administration of a sublingual glyceryl trinitrate spray (0.3 mg). A single session of hemodialysis by noncoated dialyzer impaired flow-mediated vasodilation (P<0.05) associated with increased plasma levels of oxidized LDL (P<0.05), an index of oxidative stress. Hemodialysis by vitamin E-coated membrane prevented dialysis-induced endothelial dysfunction and increases in oxidized LDL. Plasma levels of oxidized LDL were inversely correlated with the magnitudes of flow-mediated vasodilation (r=-0.53, P< 0.001). Hemodialysis by noncoated or vitamin E-coated membrane did not affect glyceryl trinitrate-induced endothelium-independent vasodilation. CONCLUSIONS: Our findings indicate that hemodialysis per se impairs endothelial function, possibly by increasing oxidative stress.

Adult↗
PubMed2000

Important role of local angiotensin II activity mediated via type 1 receptor in the pathogenesis of cardiovascular inflammatory changes induced by chronic blockade of nitric oxide synthesis in rats.

BACKGROUND: The chronic inhibition of NO synthesis by N(omega)-nitro-L-arginine methyl ester (L-NAME) upregulates the cardiovascular tissue angiotensin II (Ang II)-generating system and induces cardiovascular inflammatory changes in rats. METHODS AND RESULTS: We used a rat model to investigate the role of local Ang II activity in the pathogenesis of such inflammatory changes. Marked increases in monocyte infiltration into coronary vessels and myocardial interstitial areas, monocyte chemoattractant protein-1 (MCP-1) expression, and nuclear factor-kappaB (NF-kappaB, an important redox-sensitive transcriptional factor that induces MCP-1) activity were observed on day 3 of L-NAME administration. Along with these changes, vascular superoxide anion production was also increased. Treatment with an Ang II type 1 receptor antagonist or with a thiol-containing antioxidant, N-acetylcysteine, prevented all of these changes. CONCLUSIONS: Increased Ang II activity mediated via the type 1 receptor may thus be important in the pathogenesis of early cardiovascular inflammatory changes in this model. Endothelium-derived NO may decrease MCP-1 production and oxidative stress-sensitive signals by suppressing localized activity of Ang II.

Angiotensin II↗
PubMed2000

Gastric amyloidosis with massive bleeding requiring emergency surgery.

We report a 66-year-old woman who had massive bleeding from a gastric ulcer complicating primary systemic amyloidosis, in whom emergency surgery proved lifesaving. Physical examination revealed anemia and macroglossia. Gastroscopy was performed, and an extensive, irregular, hemorrhagic ulcer was found in the gastric body. Biopsy resulted in a diagnosis of amyloidosis. On the 11th hospital day the patient went into shock as a result of a massive hemorrhage. Emergency surgery was performed, but the extent of the submucosal lesion in the stomach could not be identified, and total gastrectomy was unavoidable. Histological examination of the surgical specimen and biopsy tissue collected from other organs revealed amyloid deposition extending from the submucosa to the muscularis propria of the stomach. There was also deposition of large amounts of amyloid around the small blood vessels in the liver and under the mucosa of the small intestine. The amyloid was AA-antibody-negative and resistant to treatment with K2MO4, and a diagnosis of AL-type systemic amyloidosis was made. The patient's general condition recovered after the operation, but on the 103rd hospital day, she experienced sudden onset of arrhythmia and died. Patients with amyloidosis in whom gastrointestinal surgery is performed are rare; only 41 cases, including our own, have been reported in the Japanese literature since 1972.

Aged↗
PubMed2000

Clonally accumulating T cells in the anterior chamber of Behçet disease.

PURPOSE: To clarify the nature of infiltrating T cells into the anterior chamber of a patient with Behçet disease. METHODS: Aqueous humor was obtained from a patient with ocular Behçet disease by paracentesis. RNA isolated from the cells in aqueous humor was reverse transcribed into complementary DNA. Complementary DNA encoding the variable (V) diversity (D) joining (J) (junctional) region of T-cell receptor beta chain V domain (TCR BV) chain was amplified by T-cell receptor BV family polymerase chain reaction. RESULTS: Polymerase chain reaction Southern blot analysis showed that T-cell receptor BV3, BV5, and BV7 were dominantly expressed on ocular T cells of this patient. In addition, DNA sequencing revealed that monoclonal or oligoclonal T-cell accumulation was found in T-cell receptor BV3(+), BV5(+), and BV7(+) T cells. CONCLUSION: These findings suggest that some T cells infiltrating into the anterior chamber of a patient with ocular Behçet disease expand by antigen-driven stimulation, indicating the pivotal role of T cells in the pathogenesis of ocular Behçet disease.

Adult↗
PubMed2000

Progressive outer retinal necrosis caused by herpes simplex virus type 1 in a patient with acquired immunodeficiency syndrome.

OBJECTIVE/BACKGROUND: To identify the etiologic agent of rapidly progressive outer retinal necrosis (PORN) in a 32-year-old man with acquired immunodeficiency syndrome (AIDS), who had retinitis developed from cytomegalovirus (CMV). Multiple yellowish spots appeared in the deep retina without evidence of intraocular inflammation or retinal vasculitis, diagnosed clinically as PORN. Death occurred after failure of multiple organs. DESIGN: Case report. METHODS: Both globes were taken at autopsy, fixed in formalin, and examined histopathologically and immunohistochemically to identify causative agents in the retinal lesions. MAIN OUTCOME MEASURE: Immunohistochemistry. RESULTS: All layers of the retina were severely damaged and contained focal calcification. Cytomegalic inclusion bodies were found in cells in the damaged retina of the right eye. Immunohistochemical studies for herpesviruses revealed the presence of CMV antigens in the right retina at the posterior pole and herpes simplex virus type 1 (HSV-1)-specific antigen in the periphery of both retinas. No varicella-zoster virus (VZV) antigen was detected in either retina. CONCLUSIONS: PORN has been described as a variant of necrotizing herpetic retinopathy, occurring particularly in patients with AIDS. Although the etiologic agent has been reported to be VZV, HSV-1 can be an etiologic agent.

AIDS-Related Opportunistic Infections↗
PubMed2000

Novel brain function: biosynthesis and actions of neurosteroids in neurons.

Peripheral steroid hormones act on brain tissues through intracellular receptor-mediated mechanisms to regulate several important brain neuronal functions. Therefore, the brain is considered to be a target site of steroid hormones. However, it is now established that the brain itself also synthesizes steroids de novo from cholesterol. The pioneering discovery of Baulieu and his colleagues, using mammals, and our studies with non-mammals have opened the door of a new research field. Such steroids synthesized in the brain are called neurosteroids. Because certain structures in vertebrate brains have the capacity to produce neurosteroids, identification of neurosteroidogenic cells in the brain is essential to understand the physiological role of neurosteroids in brain functions. Glial cells are generally accepted to be the major site for neurosteroid formation, but the concept of neurosteroidogenesis in brain neurons has up to now been uncertain. We recently demonstrated neuronal neurosteroidogenesis in the brain and indicated that the Purkinje cell, a typical cerebellar neuron, actively synthesizes several neurosteroids de novo from cholesterol in both mammals and non-mammals. Pregnenolone sulfate, one of neurosteroids synthesized in the Purkinje neuron, may contribute to some important events in the cerebellum by modulating neurotransmission. Progesterone, produced as a neurosteroid in this neuron only during neonatal life, may be involved in the promotion of neuronal and glial growth and neuronal synaptic contact in the cerebellum. More recently, biosynthesis and actions of neurosteroids in pyramidal neurons of the hippocampus were also demonstrated. These serve an excellent model for the study of physiological roles of neurosteroids in the brain, because both cerebellar Purkinje neurons and hippocampal neurons play an important role in memory and learning. This paper summarizes the advances made in our understanding of neurosteroids, produced in neurons, and their actions.

Animals↗
PubMed2000

Tetrahydrobiopterin restores endothelial function in long-term smokers.

OBJECTIVES: We sought to test whether tetrahydrobiopterin (BH4) supplementation improves nitric oxide (NO) bioactivity in smokers. BACKGROUND: In smokers, endothelium-derived NO bioactivity is impaired. BH4 is an essential cofactor of NO synthase, and its deficiency decreases NO bioactivity. METHODS: Sapropterin hydrochloride, an active analogue of BH4 (2 mg/kg body weight), was administered orally to healthy male smokers and age-matched nonsmokers. Before and 3 and 24 h after sapropterin, we measured plasma levels of BH4 and examined flow-mediated vasodilation (FMV) of the brachial artery by high resolution ultrasonography, a noninvasive test of endothelial function. RESULTS: Basal plasma levels of BH4 were not different between smokers and nonsmokers. Sapropterin administration increased plasma levels of BH4 by threefold at 3 h, which returned to the baseline at 24 h. Before sapropterin, FMV was significantly smaller in smokers (p = 0.0002). Sapropterin significantly augmented endothelium-dependent vasodilation in smokers, but did not affect it in nonsmokers (p = 0.001 by analysis of variance [ANOVA]). Coadministration of N(G)-monomethyl-L-arginine (L-NMMA), an NO synthase inhibitor (20 micromol), into the brachial artery completely abolished the vasodilatory effects of sapropterin (p = 0.002 by ANOVA). Endothelium-independent vasodilation by glyceryl trinitrate was not different between smokers and nonsmokers and was not altered by BH4. CONCLUSIONS: We demonstrated that BH4 supplementation improved bioactivity of endothelium-derived NO in smokers. These observations strongly suggest that decreased NO-dependent vasodilation in smokers could be related to reduced bioactivity of BH4.

Administration, Oral↗
PubMed2000

Interaction between inflammatory cells and heparin-surface-modified intraocular lens.

PURPOSE: To investigate the interaction and adherence of inflammatory cells to a heparin-surface-modified intraocular lens (HSM IOL). SETTING: Department of Ophthalmology, Tokyo Medical University Hospital, Tokyo, Japan. METHODS: Splenic mononuclear leukocytes from rats with experimental autoimmune uveitis were cultured with the optic of an HSM IOL for 96 hours. The number of adherent cells on the HSM IOL surface was measured with and without the addition of interphotoreceptor retinoid-binding protein and concanavalin A (ConA) to the culture medium. The adherent cells were observed under a light microscope or a scanning electron microscope. RESULTS: Interphotoreceptor retinoid-binding protein and ConA increased the number of adherent cells on the HSM IOL relative to the control. Adherent cells on the HSM IOL were small and round, considered to be mainly lymphocytes. CONCLUSION: Activated lymphocytes tended to adhere to the surface of the HSM IOL.

Animals↗
PubMed2000

Preoperative diagnosis of gallbladder torsion by magnetic resonance cholangiopancreatography.

The patient was a 78-year-old woman who was diagnosed as having gallbladder torsion preoperatively. This is the first reported case diagnosed by magnetic resonance cholangiopancreatography (MRCP). Signs and symptoms of this condition are often subtle. Radiologic evaluation by ultrasonography and computed tomography (CT) showed acute cholecystitis with stone. Drip-infusion cholangiography CT failed to outline the gallbladder, and distortion of the extrahepatic bile ducts and interruption of the cystic duct were observed. MRCP showed 1) a v-shaped distortion of the extrahepatic bile ducts due to traction by the cystic duct, 2) tapering and twisting interruption of the cystic duct, 3) a distended and enlarged gallbladder that was deviated to the midline of the abdomen, and 4) a difference in intensity between the gallbladder and the extrahepatic bile ducts and the cystic duct. A definitive diagnosis of gallbladder torsion (volvulus) was made by MRCP preoperatively. If treated surgically, gallbladder detorsion before cholecystectomy is a helpful technique to avoid bile duct injury. This condition should be suspected in elderly women with acute cholecystitis or acute abdominal pain of unknown origin, and MRCP may be very useful in making a definitive diagnosis.

Aged↗
PubMed2000

Chronic inhibition of nitric oxide synthesis in rats increases aortic superoxide anion production via the action of angiotensin II.

OBJECTIVE: Chronic inhibition of nitric oxide (NO) synthesis by Nomega-nitro-L-arginine methyl ester (L-NAME) increases vascular tissue angiotensin II activity and oxidative stress in animals by incompletely understood mechanisms. In a rat model, we investigated the role of local angiotensin II activity in the pathogenesis of increased oxidative stress. DESIGN: We studied the aortas of control rats and others receiving L-NAME or L-NAME plus an angiotensin II type 1 receptor antagonist (CS-866). RESULTS: Administration of L-NAME for 7 days significantly increased superoxide anion (O2-) and both immunoreactivity and electrophoretically demonstrable activity of redox-sensitive transcription factors (NF-kappaB and AP-1). Treatment with the angiotensin II type 1 receptor antagonist prevented all of the above changes. The observed effects of the type 1 receptor antagonist was independent of the L-NAME-induced arterial hypertension. CONCLUSIONS: These findings suggest that chronic inhibition of NO synthesis may increase vascular oxidative stress and oxidative stress-sensitive signals via the action of angiotensin II mediated via type 1 receptors.

Angiotensin II↗
PubMed2000

Role of transforming growth factor-beta1 in cardiovascular inflammatory changes induced by chronic inhibition of nitric oxide synthesis.

We previously reported that chronic inhibition of nitric oxide (NO) synthesis with N(omega)-nitro-L-arginine methyl ester (L-NAME) induces inflammatory changes (monocyte infiltration, myofibroblast formation, and monocyte chemoattractant protein-1 [MCP-1] and transforming growth factor-beta1 [TGF-beta1] expression) in the rat heart and vessel. There is debate regarding whether TGF-beta1 exhibits proinflammatory or anti-inflammatory activities. We used the rat model to investigate the role of TGF-beta in the pathogenesis of such inflammatory changes. We show here that infiltrating monocytes and myofibroblasts in the inflammatory lesions produced TGF-beta1 on the third day of L-NAME administration. Cotreatment with a monoclonal antibody against TGF-beta1, but not with control IgG, prevented the L-NAME-induced cardiac inflammation. The antibody also significantly inhibited the gene expression of MCP-1, P-selectin, and intercellular adhesion molecule-1. In summary, the antibody against TGF-beta1 prevented inflammatory changes in rat heart and vessel induced by chronic inhibition of NO synthesis, suggesting that increased production of TGF-beta1 is involved in the inflammatory changes in this model.

Animals↗
PubMed2000

The medial approach for operative release of post-traumatic contracture of the elbow.

We treated post-traumatic contracture of the elbow in 13 consecutive patients (14 elbows) by operative release. Through a single medial approach, the posterior oblique bundle of the medial collateral ligament was resected, followed by posterior and anterior capsulectomies. An additional lateral release through a separate incision was required in only four elbows. The results were assessed at a mean interval of 57 months after operation. Before surgery active extension lacked 43 degrees which improved to 17 degrees after operation. Active flexion before operation was 89 degrees, which improved to 127 degrees. The mean arc of movement increased from 46 degrees to 110 degrees. All 14 elbows showed scarring of the posterior oblique bundle of the medial collateral ligament. Neither the interval from injury to operative release nor the age of the patient affected the results. A medial approach is useful to reveal and excise the pathological changes in the medial collateral ligament. It is a safe and effective route through which to correct post-traumatic contracture of the elbow.

Adolescent↗