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T Shin

Publications and source records attributed to T Shin.

At least 91 records · Page 5Linked to original sources
PubMed1997

Myosin-induced autoimmune polymyositis in the rat.

Experimental autoimmune myositis (EAM) was induced in Lewis rats by immunization with partially purified and purified skeletal myosin. Although clinical signs such as muscle weakness were very mild, multiple inflammatory lesions in the skeletal muscle, but not in the heart, were found by histological examination. Immunohistochemical staining revealed that muscle fiber-infiltrating cells were CD8+ and CD11b+ cells and that CD4+, TCR alphabeta+, B and NK cells were mainly located in the endomysium and interfiber connective tissue. These findings were in contrast to those obtained in experimental autoimmune encephalomyelitis lesions in which CD4+ cells predominate over CD8+ cells. T cells and sera isolated from myosin-immunized animals responded vigorously to myosin. However, neither sensitized lymphoid cells mainly comprising CD4+ cells nor purified anti-myosin immunoglobulin G mediated the disease into naive rats, suggesting that T cells other than CD4+ cells such as CD8+ cells may be the final effector. Taken together, EAM induced in Lewis rats is similar to human polymyositis (PM). EAM can serve as a good model for human PM and give insight into the pathogenesis of the disease.

Adoptive Transfer↗
PubMed1997

Strain activation of bovine aortic smooth muscle cell proliferation and alignment: study of strain dependency and the role of protein kinase A and C signaling pathways.

Smooth muscle cell (SMC) phenotype can be altered by physical forces as demonstrated by cyclic strain-induced changes in proliferation, orientation, and secretion of macromolecules. However, the magnitude of strain required and the intracellular coupling pathways remain ill defined. To examine the strain requirements for SMC proliferation, we selectively seeded bovine aortic SMC either on the center or periphery of silastic membranes which were deformed with 150 mm Hg vacuum (0-7% center; 7-24% periphery). SMC located in either the center or peripheral regions showed enhanced proliferation compared to cells grown under the absence of cyclic strain. Moreover, SMC located in the center region demonstrated significantly (P < 0.005) greater proliferation as compared to those in the periphery. In contrast, SMC exposed to high strain (7-24%) demonstrated alignment perpendicular to the strain gradient, whereas SMC in the center (0-7%) remained aligned randomly. To determine the mechanisms of these phenomena, we examined the effect of cyclic strain on bovine aortic SMC signaling pathways. We observed strain-induced stimulation of the cyclic AMP pathway including adenylate cyclase activity and cyclic AMP accumulation. In addition, exposure of SMC to cyclic strain caused a significant increase in protein kinase C (PKC) activity and enzyme translocation from the cytosol to a particulate fraction. Further study was conducted to examine the effect of strain magnitude on signaling, particularly protein kinase A (PKA) activity as well as cAMP response element (CRE) binding protein levels. We observed significantly (P < 0.05) greater PKA activity and CRE binding protein levels in SMC located in the center as compared to the peripheral region. However, inhibition of PKA (with 10 microM Rp-cAMP) or PKC (with 5-20 ng/ml staurosporine) failed to alter either the strain-induced increase in SMC proliferation or alignment. These data characterize the strain determinants for activation of SMC proliferation and alignment. Although strain activated both the AC/cAMP/PKA and the PKC pathways in SMC, singular inhibition of PKA and PKC failed to prevent strain-induced alignment and proliferation, suggesting either their lack of involvement or the multifactorial nature of these responses.

Activating Transcription Factor 2↗
PubMed1997

Competitive PCR quantification of pro- and anti-inflammatory cytokine mRNA in the central nervous system during autoimmune encephalomyelitis.

Experimental autoimmune encephalomyelitis (EAE) is an inflammatory disease of the central nervous system that can be induced by immunization with myelin basic protein (MBP)/complete Freund's adjuvant and serves as a model for multiple sclerosis. Recent studies have suggested that cytokines play a crucial role in the clinical course of EAE. To clarify the roles of cytokines in EAE, we examined levels of interferon-gamma (IFN-gamma), tumor necrosis factor-alpha (TNF-alpha), transforming growth factor-beta1 (TGF-beta1) and interleukin-10 (IL-10) mRNA in isolates from infiltrating inflammatory cells in EAE lesions induced in Lewis rats. The non-radioactive and sensitive competitive PCR method was employed to quantify the relative amounts of cytokine mRNA. Levels of both IFN-gamma and TNF-alpha mRNA were increased at the early stage of EAE and rapidly decreased at the peak stage. On the other hand, TGF-beta1 mRNA was demonstrated throughout the course of EAE as well as under normal conditions and its amount paralleled the severity of EAE. IL-10 mRNA was detected by reverse transcription polymerase chain reaction (RT-PCR) under normal conditions, but was below the level of detection of competitive PCR. IL-10 mRNA expression peaked at the early stage of EAE and declined gradually thereafter. Taken together, these results suggest that IFN-gamma and TNF-alpha might play a crucial role in the development of EAE. Furthermore, it appears that the peak expression of IL-10 mRNA at the early stage and the following marked TGF-beta1 expression at the peak stage might represent an important endogenous mechanism to limit the extent of inflammation and to prevent relapse in the course of acute monophasic EAE.

Animals↗
PubMed1997

Characteristics of laryngeal receptors analyzed by presynaptic recording from the cat medulla oblongata.

In order to clarify the neural mechanisms for the protective laryngeal reflex, we conducted physiological analysis of laryngeal sensory receptors. In the present study, presynaptic unit activities, which might accurately reflect characteristics of the laryngeal receptor, were recorded with a glass microelectrode in the nucleus of the tractus solitarius of the medulla oblongata in ketamine-urethane anesthetized cats, and the responses to the mechanical and/or chemical stimuli were analyzed. From the results, it was demonstrated that highly sensitive mechanoreceptors and polymodal receptors exist in the laryngeal mucosa; they are particularly numerous in the laryngeal surface of the epiglottis and arytenoid region, and uncommon in the vocal fold. Mechanoreceptors on the laryngeal mucosa were classified into a rapidly adapting group and a slowly adapting group, while all polymodal receptors adapted rapidly to mechanical stimulation. These results suggest that these non-specific polymodal and rapidly adapting receptors may correspond to more superficial receptors such as free nerve endings and some taste buds, and also monomodal slowly adapting mechanoreceptors may correspond to deeper terminals in the subepithelium. It is also considered possible that the structures and the characteristics of these receptors are appropriate to elicit the protective laryngeal reflexes by non-specifically detecting various kinds of stimuli.

Animals↗
PubMed1996

Occipital morphology. An anatomic guide to internal fixation.

STUDY DESIGN: The authors present the results of an anatomic study of the human occiput to delineate appropriate screw placement sites. OBJECTIVES: Occipital bone morphologic characteristics were evaluated to determine whether significant variability exists and to determine the position of greatest bone thickness for safe and effective internal fixation. SUMMARY OF BACKGROUND DATA: New instrumentation and techniques for occipital fixation are being developed in response to concerns about occipital bone variability. Thirty cadaveric occiputs were evaluated to determine if such variability exists and the location of greatest bone thickness. Radial thickness, occipital locations, and gender differences, were determined. METHODS: Twenty-six skulls were sectioned sagittally to determine the contributions of the inner, middle, and outer tables to overall occipital thickness. The angle required to gain maximal cortical purchase was determined. Mean values and variance were analyzed statistically to determine variability and thickness. Data was plotted in three dimensions. Variability in morphologic features was minimal. RESULTS: The internal occipital protuberance-external occipital protuberance was thickest at 17.55 mm (SD = 3.18 mm) and was consistently located on the superior nuchal line 43 degrees from the horizontal skull base line. Bone thickness decreased radially from the central internal occipital protuberance position. Bone thickness above the superior nuchal line exceeded that below by 2.74 mm (P < 0.05) vertically and at the oblique positions (P < 0.05). Bone to the right of the midline was only 1 mm thicker than that to the left. Gender differences were minimal. The inner table contributed only 10% to overall occipital thickness. As occipital thickness decreased, the optimal purchase angle increased. CONCLUSIONS: Unicortical purchase at and above the superior nuchal line is warranted with a low risk of intracranial venous penetration. Internal fixation devices developed in response to occipital bone variability should be considered with respect to occipital bone thickness distributions. Attention to cervical morphologic characteristics should result in higher success rates in occipitocervical arthrodesis.

Bone Plates↗
PubMed1996

Pretreatment with T cell receptor peptides using a conventional immunization protocol does not induce effective protection against autoimmune encephalomyelitis.

It was previously reported that vaccination with synthetic peptides corresponding to the CDR2 or CDR3 region of T cell receptor (TCR) protected susceptible animals from the development of experimental autoimmune encephalomyelitis (EAE). However, recent studies by several research groups have revealed that TCR peptide therapy often confers little or no protection from autoimmune disease. In the present study, we attempted to find more appropriate peptides that is capable of conferring effective protection against the development of EAE. Four peptides corresponding to parts of the V beta region (13-23, 24-36, 39-59, and 64-74) were selected by epitope scanning and hydrophilicity searching, and their protective abilities were tested. All these peptides were, however, ineffective in protecting rats from the disease. We also generated three different synthetic peptides corresponding to the TCR J region of encephalitogenic T cells. Vaccination with the J-region peptides did not protect animals from the development of EAE. Rather, one of the peptides (V beta-DSS-J beta 2.6) enhanced the clinical severity of EAE and induced fatal disease in some rats. Taken together, TCR peptide therapy appears to be generally ineffective and elucidation of the mechanism by which EAE is enhanced after TCR peptide vaccination should provide insight into the pathogenesis of this disease.

Amino Acid Sequence↗
PubMed1996

Reconstruction of the laryngeal mucosa. A three-dimensional collagen gel matrix culture.

OBJECTIVE: To prepare an in vitro reconstruction of the porcine laryngeal mucosa, for use in cell biological investigations and as a model for the study of laryngeal disease. DESIGN: Using separately obtained epithelial cells and fibroblasts from porcine laryngeal mucosa, we reconstructed the laryngeal mucosa in a three-dimensional collagen gel matrix culture with air-liquid interface. SUBJECTS: Porcine larynges were from 6-month-old pigs obtained from a local abattoir. RESULTS: We successfully reconstructed the laryngeal mucosa in vitro, including epithelium and lamina propria. The epithelial cells showed five to eight cells in thickness and were well differentiated on the reconstructed lamina propria. The differentiation-specific cytokeratin was positive. CONCLUSIONS: To our knowledge, this is the first report of a reconstruction of the laryngeal mucosa in a three-dimensional collagen gel matrix culture. Fibroblasts and air-liquid interface treatment exert a great influence on the proliferation and differentiation of the cultured epithelial cells. This culture system will help to provide an appropriate physiologic environment to study the differentiation and disease of the larynx.

Animals↗
PubMed1996

Characterization of CD4-CD8- T cell receptor alpha beta + T cells appearing in the subarachnoid space of rats with autoimmune encephalomyelitis.

Inflammation of the central nervous system (CNS) in experimental autoimmune encephalomyelitis (EAE) starts in the subarachnoid space (SAS) and spreads later to the adjacent CNS parenchyma. To characterize the nature of lesion-forming T cells in situ in more detail, T cells were isolated from the SAS and their surface phenotype and the nucleotide sequence of the junctional region of the T cell receptor (TCR) was determined and compared with those of the lymph node (LN) and spinal cord (SC) T cells. Characteristically, more than 70% of SAS TCR alpha beta + T cells isolated at the early stage of EAE lacked both CD4 and CD8 molecules, whereas those from LN and SC were either CD4+ or CD8+. Analysis of nucleotide sequences of the junctional region of TCR revealed that T cells bearing a sequence identical to that for encephalitogenic T cell clones were found in both SAS and SC. Furthermore, purified CD4-CD8- T cells expressed CD4 molecules after culture. At the same time, these T cells acquired reactivity to myelin basic protein and induced passive EAE in naive animals after adoptive transfer. Our results suggest that CD4-CD8- T cells in the SAS are precursors of lesion-forming T cells in the SC and that phenotype switching takes place during the process of T cell infiltration into the CNS parenchyma. The double-negative nature of these T cells may explain an escape of encephalitogenic T cells from negative selection in T cell differentiation.

Amino Acid Sequence↗
PubMed1996

Neuroendocrine cells in the cat laryngeal epithelium.

The structure and distribution of neuroendocrine cells in the feline laryngeal epithelium were examined using immunohistochemical techniques. Neuroendocrine cells were often spindle shaped, with cytoplasmic processes directed towards the lumen and basement membrane. The apical portion of the cells usually reached the laryngeal lumen with microvillous projections. The cytoplasm always contained variable numbers of electrondense cored vesicles. The number of neuroendocrine cells decreased in the following order: subglottis, posterior glottis, supraglottis, anterior glottis. Neuroendocrine cells contained calcitonin gene-related peptide, substance P and/or 5-hydroxytryptamine. They also showed protein gene product 9.5 or neuron-specific enolase immunoreactivity. These observations suggest that neuroendocrine cells play a part in the regulatory function of the cat larynx by releasing various peptides. These substances may contribute to allergic reactions or control mucus secretion by acting via the endocrine or paracrine pathways and/or neurosecretory pathways.

Animals↗
PubMed1996

Novel beta-D-galactofuranose-containing high-mannose type oligosaccharides in ascorbate oxidase from Acremonium sp. HI-25.

Ascorbate oxidase from the fungus Acremonium sp. HI-25 is a copper-containing glycoprotein that catalyzes the oxidation of ascorbic acid to dehydroascorbic acid. Monosaccharide composition analysis showed that the enzyme contains exclusively N-linked oligosaccharide chains. Following liberation by hydrazinolysis/re-N-acetylation, and fractionation by HPLC on anion exchange. Amide-80 and/or octadecyl silica columns after derivatization with p-aminobenzoic ethyl ester, the structures of the twelve major neutral oligosaccharides were identified by FAB-MS, 400 MHz 1H-NMR, methylation analysis, mild acid hydrolysis, and/or sequential exoglycosidase digestions. Acremonium sp. ascorbate oxidase was found to consist of high-mannose type oligosaccharides (76.3%) having 4 to 9 mannose residues and a series of novel D-galactofuranose-containing high-mannose type oligosaccharides (18.6%) with the following structure.

Acremonium↗
PubMed1996

MR imaging of cerebral activation performed with a gradient-echo technique at 1.5 T: sources of activation signals.

OBJECTIVE: MR imaging of cerebral activation has been successfully performed at 1.5 T for functional maps of the brain. However, major sources of activation signals in such imaging remain controversial. The purpose of this study is to investigate anatomic and physiologic sources of activation signals in MR imaging of cerebral activation performed with a gradient-echo technique at 1.5 T. SUBJECTS AND METHODS: Motor cortex activation studies (n = 8) were conducted using a gradient-echo technique (80/60 [TR/TE], 40 degrees flip angle). MR venograms were then obtained at the same imaging plane to visualize the cortical veins, which were then compared with the shape and location of the activation signals. To investigate the physiologic sources of activation signal, the activation studies were repeated with different TEs (15, 30, and 60 msec), which allowed us to evaluate the blood oxygen level-dependent effect; with different flip angles (40 degrees and 10 degrees); and without and with presaturation of adjacent sections, all of which allowed us to evaluate inflow effect. RESULTS: All activation signals were detected in the sulcus just posterior (n = 7) or lateral (n = 1) to the motor cortex. In seven of eight studies, shape and location of these signals corresponded well with those of the cortical veins. In the eighth study, the correspondence was partial. Activation signals significantly increased at a TE of 60 msec (p < .01), suggesting enhancement of the blood oxygen level-dependent effect at a long TE. Activation signals significantly decreased with a 10 degrees flip angle (p < .01) and with presaturation of adjacent sections (p < .01), indicating that the inflow effect was suppressed by a small flip angle and the elimination of unsaturated inflowing protons. CONCLUSION: Our results suggest that signals in cerebral activation obtained by MR imaging with a gradient-echo technique at 1.5 T arise mainly from the cortical veins draining the activated cortex. Physiologically, both blood oxygen level-dependent and inflow effects contribute to signal generation.

Adult↗
PubMed1995

The subarachnoid space as a site for precursor T cell proliferation and effector T cell selection in experimental autoimmune encephalomyelitis.

To characterize the phenotype of inflammatory cells in the central nervous system (CNS) in experimental autoimmune encephalomyelitis (EAE), Lewis rats were immunized with guinea pig myelin basic protein and frozen sections of the spinal cord with EAE were examined immunohistochemically using a panel of monoclonal antibodies against T cells and adhesion molecules. In addition, double immunostaining was performed with glial and T cells markers to examine the interaction between infiltrating T cells and reactive brain cells during the course of EAE. In the early stage of EAE, inflammatory cells first appeared in the subarachnoid space (SAS) and infiltrated the subpial region. The majority of inflammatory cells in SAS expressed TCR alpha beta and either CD4 or CD8 molecules. However, only CD4+ T cells infiltrated the parenchyma while the majority of CD8+ cells remained in SAS. A similar differential localization of T cells was observed with regard to CD45RC molecules. Inflammatory cells in SAS consisted of both CD45RC+ and CD45RC- population, while those in the parenchyma were largely CD45RC-. With regard to adhesion molecules, the leptomeninges constitutively expressed fibronectin (FN) and intercellular adhesion molecule 1 (ICAM-1). Most SAS inflammatory cells expressed very late activation antigen 4 (VLA-4) and, to lesser extent, lymphocyte function-associated antigen 1 (LFA-1) in the early stage of EAE. On the other hand, parenchymal infiltrating cells expressed LFA-1 more strongly in the peak stage. Double staining for V beta 8.2 TCR and microglia demonstrated an increase in the number of microglia together with morphological changes into rod-shape cells in the vicinity of infiltrating T cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

Convergence of afferents from the SLN and GPN in cat medullary swallowing neurons.

We demonstrated the convergence of information from the pharyngeal and laryngeal mucosa, transmitted by the glossopharyngeal nerve (GPN) and superior laryngeal nerve (SLN), in the nucleus of the tractus solitarius (NTS). First, the distribution of terminals of the GPN and SLN in the NTS was examined by an HPR tracing technique in cats, and the synapse formation of these neurons with NTS neurons was demonstrated by electron microscopy. The HRP-labeled SLN and GPN terminals were localized in a small area of the interstitial subnucleus of the NTS, slightly rostral to the obex, forming synapses with NTS neurons. Next, using extracellular recording in anesthetized cats, we determined whether or not swallowing-related neurons in the medulla oblongata receive peripheral inputs. Convergence of peripheral sensory inputs from the SLN and GPN was observed in more than 80% of the NTS cells. These results suggest that the NTS is not only a sensory-relay nucleus but also integrates information necessary for eliciting protective reflexes of the upper airway, such as swallowing.

Afferent Pathways↗
PubMed1995

Convergence of laryngeal afferents with different natures upon cat NTS neurons.

To clarify the convergence of laryngeal afferents within the nucleus tractus solitarius (NTS) in the cat, we examined in the medulla the response characteristics of superior laryngeal nerve (SLN) fibers and NTS neurons to mechanical and chemical stimulation applied to laryngeal mucosa by extracellular recordings. The response was recorded in 75 SLN primary afferent fibers (PAFs) and 92 NTS neurons. PAFs of the SLN consisted of numerous monomodal mechanosensitive fibers and a small number of chemosensitive and polymodal fibers. On the other hand, the majority of NTS neurons had a polymodal nature. Thus, laryngeal information is considered to be integrated in modality into NTS neurons. All mechanosensitive fibers received information from a small restricted field in the larynx. On the contrary, each NTS neuron responded to mechanical stimulation over a wide laryngeal field, indicating that information from different sites spatially converge on NTS neurons. Our results suggest that caudal NTS neurons play a cardinal role in integrating laryngeal afferents, which are thought to elicit laryngeal reflexes.

Afferent Pathways↗
PubMed1995

Effects of alpha- and beta-arbutin on activity of tyrosinases from mushroom and mouse melanoma.

The effects of alpha- and beta-arbutin on the activity of tyrosinases from mushroom and mouse melanoma were examined. alpha-Arbutin was synthesized from hydroquinone and starch using glucoside synthetase (GSase). beta-Arbutin inhibited both tyrosinase activities from mushroom and mouse melanoma. alpha-Arbutin inhibited only the tyrosinase from mouse melanoma, 10 times as strongly as beta-arbutin. The IC50 of alpha-arbutin was 0.48 mM and its inhibitory mechanism was speculated to be mixed type inhibition, while that of beta-arbutin was noncompetitive.

Animals↗