Biomedical subjects

E Tanaka

Publications and source records attributed to E Tanaka.

At least 109 records · Page 6Linked to original sources

PubMed2000

Changes in the biomechanical properties of the rat interparietal suture incident to continuous tensile force application.

This study was designed to investigate the relation between the biomechanical behaviour of rat interparietal sutures and expansion forces placed on them. Thirty-five 4-week-old rats were divided into four groups, a control group and three experimental groups subjected to mechanical expansion of the interparietal sutures with a tensile force for 15, 30 and 50 h. After expansion, the parietal bones, including the interparietal suture, were dissected as specimens for tensile tests. Under tension, the relaxed stress-strain plots in the control group could be better fitted by a power of 2.00, and the relaxed moduli were 0.64 and 4.51 MPa at the lower and the higher applied strains, respectively. An initial fall in the relaxed moduli at 15 h of expansion was followed by an increase over time. It is therefore suggested that the biomechanical behaviour of the interparietal sutures is influenced by the duration of an external force.

Animals↗

PubMed2000

Effects of tensile forces on the expression of type III collagen in rat interparietal suture.

The aim was to investigate the direct contribution of mechanically induced stress to synthesized type III collagen in the interparietal suture. Twenty 4-week-old male rats were used as experimental animals. An activated expansion spring was placed across the interparietal suture. After expansion, the parietal bones including the suture were dissected and immunostained for type I and III collagens. Also, a three-dimensional model of the interparietal suture was developed to analyze stress during expansion. The localization of type III collagen in the suture was dependent upon the duration of expansion. Although the control suture exhibited no or little reactivity for type III collagen, it was observed as early as 15 h of expansion in the cambial layers, and was distributed throughout the suture at 50 h of expansion. The time-dependent distribution of type III collagen was fully consistent with that of tensile stresses calculated by the use of a three-dimensional finite-element model. It was concluded that the increases in tensile stress are associated with the synthesis of type III collagen in the suture.

Animals↗

PubMed2000

Na+/Ca2+ exchanger activity induces a slow DC potential after in vitro ischemia in rat hippocampal CA1 region.

In rat hippocampal CA1 neurons recorded intracellularly from tissue slices, a rapid depolarization occurred approximately 5 min after application of ischemia-simulating medium. In extracellular recordings obtained from CA1 region, a rapid negative-going DC potential (rapid DC potential) was recorded, corresponding to a rapid depolarization. When oxygen and glucose were reintroduced after generating the rapid depolarization, the membrane further depolarized and the potential became 0 mV after 5 min. Contrary, the DC potential began to repolarize slowly and subsequently a slow negative-going DC potential (slow DC potential) occurred within 1 min. A prolonged application of ischemia-simulating medium suppressed the slow DC potential. Addition of a high concentration of ouabain in normoxic medium reproduced a rapid but not a slow DC potential. The slow DC potential was reduced in low Na+- or Co2+-containing medium, but was not affected in low Cl-, high K+ or K+-free medium, suggesting that the slow DC potential is Na+-and Ca2+-dependent. Ni2+ (Ca2+ channel blocker as well as the Na+/Ca2+ exchanger blocker) and benzamil hydrochloride (Na+/Ca2+ exchanger blocker) reduced the slow DC potential dose-dependently. These results suggest that the slow DC potential is mediated by forward mode operation of Na+/Ca2+ exchangers in non-neuronal cells, and that reactivation of Na+, K+-ATPase is necessary to the Na+/Ca2 +exchanger activity.

Action Potentials↗

PubMed2000

T cell repertoire in the liver of patients with primary biliary cirrhosis.

Primary biliary cirrhosis (PBC) is an autoimmune chronic liver disease characterized by the destruction of the bile ducts with an accumulation of lymphocytes. To investigate the roles of T cells accumulating around the bile ducts, we analyzed the clonality of alphabeta T cell populations in the livers of patients with PBC by size spectratyping and sequencing of the T cell receptor (TCR) Vbeta transcripts.TCR Vbeta spectratyping of PBC patients showed several skewed complementarity determining region 3 (CDR3) size patterns suggestive of clonal predominance as well as Gaussian-like patterns suggestive of polyclonal expansion. We observed Vbeta4 clones sharing the Gly (G)-G motif in the CDR3 nDn regions and a Vbeta4-Jbeta2.7 combination in three patients bearing HLA-DR2 and -DQ1. G-Leu (L)-Ala (A) or G-L motifs were also seen in the nDn regions of Vbeta17 with Jbeta2.1 of the two patients having HLA-A26. However, there were no whole CDR3-shared clones in any of the patients. In conclusion, we have observed that T cell clones are heterogeneous in each patient, but that they have some common motifs in the TCR Vbeta CDR3. We strongly suggest that these clonally expanded T cells might be involved in the immunopathogenesis of PBC.

Amino Acid Sequence↗

PubMed2000

Enzymatic properties of the proteasome purified from starfish oocytes and its catalytic subunits involved in oocyte maturation.

The 20S proteasome was purified from oocytes of the starfish Asterina pectinifera and its enzymatic properties were investigated. The chymotrypsin-like activities were potently inhibited by PSI as well as MG115, whereas the trypsin-like and peptidyl-glutamyl peptide-hydrolyzing (PGPH) activities were not or only weakly inhibited by PSI and MG115. The inhibitory ability of MG115 toward germinal vesicle breakdown (GVBD) coincided with those toward the trypsin-like and PGPH activities, and PSI showed no inhibitory effect on GVBD. We have previously reported that the inhibition pattern toward GVBD of peptidyl-argininals, which potently inhibited the proteasomal trypsin-like activity rather than the chymotrypsin-like activity, correlated with the inhibition pattern toward the chymotrypsin-like activity of the proteasome. These results, together with the peptidyl-argininals scarcely inhibiting the PGPH activity at concentrations sufficient for the inhibition toward GVBD, indicate that both the chymotrypsin-like and trypsin-like activities, but not the PGPH activity, of the proteasome are responsible for degradation of the physiological substrate during starfish oocyte maturation. It was also suggested that the inhibition of a single catalytic site of the proteasome is not sufficient for prevention of the proteasomal function.

Animals↗

PubMed2000

The role of hepatitis C virus infection in glomerulopathy.

The characteristics and prevalence of hepatitis C virus (HCV)-associated glomerulopathy remain to be determined. To analyze the relationship between HCV infection and glomerulopathy, we enrolled three groups of individuals or patients. The first group consisted of 7776 individuals who were seen for routine checkups. The second group consisted of 86 patients with chronic hepatitis C, 40 patients with chronic hepatitis B, and 51 patients with non-viral liver diseases. The third group consisted of nine patients with HCV association glomerulopathy who underwent renal biopsy. Of the 7776 individuals undergoing medical checkups, 142 (1.8%) were positive for HCV antibody. The positive rate of proteinuria was significantly higher (P<0.030) in individuals with HCV antibody (2.1%) than in those without the antibody (0.6%). Abnormal levels of serum creatinine (5.8 vs. 0%, P=0.025) and complications of cryoglobulinemia (45 vs. 5%, P<0.001) were significantly more common in the 86 patients with chronic hepatitis C (5.8%) than in the 91 patients with other liver diseases. All patients with abnormal levels of serum creatinine had concomitant cryoglobulinemia. Of the nine patients with histologically proven HCV-associated glomerulopathy, four had cryoglobulinemia (all were type II). Elevations of serum creatinine level (4/4 vs. 0/5, P=0.048) and a glomerular legion of membranoproliferative glomerulonephritis (3/4 vs. 0/5, P=0.048), a severe type of glomerulonephritis, were more common in the four patients with cryoglobulinemia than in the remaining five patients. In conclusion, HCV infection was found to be significantly associated with glomerulopathy. In addition, the presence of cryoglobulinemia, which usually accompanies membranoproliferative glomerulonephritis, was found to be an indicator of renal insufficiency in patients with HCV-associated glomerulopathy.

Journal Article↗

PubMed2000

Analysis of T cell repertoire in the liver of patients with chronic hepatitis C.

Many T cells infiltrate into the liver of patients with chronic hepatitis C (CH-C). They are believed to play a crucial role in the immunopathogenesis of hepatic inflammation, but their clonality and specificity are unknown. The aim of this study was to clarify the characteristics of these T cells. We analysed the complementarity-determining region (CDR)3 size lengths of T cell receptor (TCR) beta-chains by size spectratyping, and determined the sequences of Vbeta CDR3 after subcloning Vbeta-specific polymerase chain reaction products. Spectratyping showed clonal expansions in all liver specimens, most of which showed more than two T cell clones. Moreover, many non-clonal T cells also accumulated in the liver. Clonality of the T cells suspected by spectratyping was confirmed by CDR3 sequencing. Although the sequences revealed no whole CDR3-shared clones among different patients, some common motif sequences were observed. Our data suggest that T cells are stimulated by several hepatitis C virus (HCV) epitopes, then accumulate in the liver of CH-C patients. Shared motifs of expanded T cell clones suggest that they might recognize the same regions of HCV peptides, but have differences due to HCV peptide mutational changes. These clones might also interact with non-clonal T cells and play a crucial role in the immunopathogenesis of CH-C.

Female↗

PubMed2000

Cytochrome P450 2E1: its clinical and toxicological role.

Cytochrome (CYP) P450 2E1 is clinically and toxicologically important and it is constitutively expressed in the liver and many other tissues. In contrast to many other CYP isoenzymes, indisputable evidence for a functionally important polymorphism of CYP2E1 in the human population is lacking. CYP2E1 metabolizes a wide variety of chemicals with different structures, in particular small and hydrophobic compounds, including potential cytotoxic and carcinogenic agents. In addition, chlorzoxazone and trimethadione metabolism are good CYP2E1 probes for liver disease in vivo and in vitro. In the future, methods for fully analysing the function of CYP2E1 using knockout mice will be established. This article reviews recent advances in our understanding of the role of human CYP2E1 in drug metabolism.

Anesthetics↗

PubMed2000

Update: the clinical importance of acetaminophen hepatotoxicity in non-alcoholic and alcoholic subjects.

Acetaminophen (paracetamol) is one of the most commonly used over-the-counter medications. Taken in doses greater than 150 mg/kg/day (>10 g), it usually causes acute liver failure. The authors review mainly the management of acetaminophen toxicity in both users and nonusers of alcohol. Chronic alcoholics are a special subgroup, who risk serious toxicity when taking acetaminophen, even in therapeutic doses. The acetaminophen-alcohol interaction is complex, because acute and chronic ethanol have opposite effects. This review also considers physiological and clinical changes, as well as the diagnosis and treatment of acetaminophen poisoning.

Acetaminophen↗

PubMed2000

The clinical importance of conventional and quantitative liver function tests in liver transplantation.

The advantages and disadvantages of using monoethylglycinexylidide (MEGX), the major metabolite of lidocaine, as a probe of hepatic function in liver transplantation are reviewed. A 'real time' test of liver function should give a measure of current hepatocellular capacity rather than reflect past damage. The hepatic metabolism of lidocaine to MEGX is the basis of a flow-dependent dynamic test of liver function. In pre-transplantation patients, data from this MEGX test support its role in assessing the risk of morbidity and mortality. In assessing the liver transplant donor, there are differences concerning its apparent usefulness and these must be resolved. In the liver transplant recipient, this MEGX test is also useful for measuring real-time hepatic metabolizing activity, and low MEGX values reflect the clinical condition of the patient. At present, however, this test has several limitations. Therefore, a comprehensive evaluation, not only by the MEGX test but also by a combination of other conventional liver function tests (biochemical parameters, etc.), or with histological evaluation, is thought to be desirable for deciding whether a liver transplantation should be carried out or not.

Chlorzoxazone↗

PubMed2000

Stress distribution in the temporomandibular joint affected by anterior disc displacement: a three-dimensional analytic approach with the finite-element method.

The purpose of this study was to investigate the influences of anterior disc displacement on TMJ loading during maximum clenching by use of finite-element analysis. Based on a young human dry skull, an analytic model of the mandible including the TMJ was developed. In addition to the standard model with normal disc-condyle relation, two models were designed to simulate various degrees of anterior disc displacement. In the standard model, compressive stresses were induced in the anterior, middle and lateral areas on the condyle and glenoid fossa, whereas tensile stresses were observed in the posterior and medial regions. In the models with anterior disc displacement, compressive stresses were recognized in all the areas of TMJ components excluding the bilaminar zone. Shear stresses in the articular disc and bilaminar zone significantly increased in most areas. In conclusion, stress distributions in the TMJ with a normal disc position was substantially different from those with anterior disc displacement, suggesting that the progress in disc displacement may have some association with the nature of stress distributions in the TMJ, in the articular disc in particular.

Bite Force↗

PubMed2000

Natural history of acute hepatitis C.

To study the short- and long-term outcomes of acute hepatitis C, three groups of patients were enrolled. Of 26 patients with acute hepatitis C, 18 (69%) maintained HCV viraemia and 8 had cleared virus naturally at 12 months after the onset. Normalization of ALT was seen in all 8 patients with acute resolving hepatitis, but in only 1 (5%) of the 18 patients with chronic HCV infection (P< 0.001). Changes in liver histology were analysed in 43 patients with acute hepatitis C who underwent repeated liver biopsy. The mean score of the fibrotic stage was 0.9 within 1 year of the onset, and it increased gradually up to 3.5 at 30 years from the onset (0.1 grade/year). The fibrotic stage increased more rapidly in patients aged more than 50 years. In 115 patients, the mean duration between blood transfusion and the diagnosis of HCC increased significantly (P< 0.001) in accordance with increasing age at blood transfusion; 35 +/- 5.3 years in patients aged less than 30 years, 30 +/- 4.9 years in those aged between 30 and 40 years, and 25 +/- 6.8 years in those aged more than 40 years. In conclusion, approximately 70% of patients with acute hepatitis C develop chronic hepatitis. Once patients develop chronic hepatitic fibrosis of the liver, it progresses over several decades, faster in older patients.

Acute Disease↗

PubMed2000

Relationship between histological prognosis of chronic hepatitis C and amount of hepatitis C virus core protein in serum.

BACKGROUND: Hepatitis C virus (HCV) viraemia is one of the factors for histological prognosis of chronic hepatitis C. METHODS: One hundred and thirty-five patients who received hepatic biopsies twice at intervals of 5 years or longer were followed up for a mean of 9.7 +/- 4.0 years were studied retrospectively. The amount of HCV viraemia present was measured as the concentration of HCV core protein by using the fluorescence enzyme immunoassay method. RESULTS: Multiple-regression analysis, using deterioration of the histological stage as a dependent variable, showed that greater age (P = 0.041), higher stage of hepatic histology at the start of follow up (P = 0.029), and higher serum concentration of core protein (P < 0.001) were independent factors affecting the deterioration of the liver's histological stage. At follow up, no significant difference in histological stage was seen between patients with serum HCV core protein > or = 100 pg/mL (n = 60) and those with serum core protein < 100 pg/mL (n = 75). The histological grade in patients with high serum core-protein levels tended to be significantly worse and the deterioration rate of the histological stage was significantly higher than in those with low HCV core protein levels (68 vs 35%, P < 0.001). The mutation rate of the HCV envelope-2/non-structural 1 (E2/NS1) nucleotide region was compared in two patients who had high serum concentrations of HCV core protein and whose histological stage had deteriorated with two patients who had low serum concentrations of the core protein and whose histological stages remained unchanged. No significant difference in E2/NS1 mutation was found. CONCLUSIONS: The amount of HCV viraemia was suggested to be a significant factor for determining histological outcome in patients with chronic hepatitis C. The mutation rate in the E2/NS1 region did not seem to be associated with the prognosis of chronic hepatitis C.

Adult↗

PubMed2000

Evaluation of the histologic effect of chemoradiation therapy for squamous cell carcinomas of the esophagus by assessing morphologic features of surgical specimens.

The histologic effects of chemoradiation therapy (CRT) for esophageal cancer, which determine the benefit obtained from a salvage operation, are difficult to evaluate preoperatively. We therefore investigated whether or not the morphologic features of esophageal cancer tissue after CRT can be correlated with the histologic features of the tissue. Seventy-six patients with advanced esophageal squamous cell carcinoma underwent CRT followed by esophagectomy. The effects of CRT were evaluated by histologic examination of the residual tumors in the surgical specimen and correlated with clinicopathologic factors, including postoperative prognosis. The histologic effects of CRT were used to classify tumors as grade 1 (CRT poorly effective; 23 cases, 30.3%); grade 2 (CRT moderately effective; 31 cases, 40.8%); or grade 3 (CRT completely effective with no residual tumors; 22 cases, 28.9%). Among the gross findings of the removed esophagus, significant correlation with the CRT effects was observed in the case of wall thickness and ulceration but not in the case of longitudinal tumor length. Tumors with no wall thickening or ulceration were never classified as grade 1, whereas tumors with both wall thickening and ulceration were frequently rated as grade 1 (18/30, 60%). Microscopic examination of grade 2 tumors (23/31, 74.1%) revealed residual tumor cells growing below the mucosal layer, whereas tumor cells were exposed to the esophageal surface in 22 out of 23 patients with grade 1 tumors. The morphologic features after CRT can be used to evaluate its histologic effect, especially in the case of grade 1 tumors. However, the detection and prediction of grade 2 tumors remains difficult because of the presence of small amounts of residual tumor underneath the mucosa.

Antineoplastic Combined Chemotherapy Protocols↗

PubMed2000

Motions of the posterior pharyngeal wall in human swallowing: a quantitative videofluorographic study.

OBJECTIVE: To quantify segmental motions of the posterior pharyngeal wall during swallowing. DESIGN: Prospective study. SETTING: Hospital radiology suite. PARTICIPANTS: Six healthy adult volunteers. INTERVENTIONS: Videofluorography of the pharynx in posteroanterior and lateral projections during water swallows by 6 able-bodied adults. Radiopaque suction markers, inserted through the nose, were attached by suction to the midline of the posterior pharyngeal wall of the upper and lower oropharynx, pharyngoesophageal segment (PES), or cervical esophagus. MAIN OUTCOME MEASURES: Displacement of the larynx, hyoid bone, and markers. RESULTS: Marker pathways were ovoid in the oropharynx but linear in the PES and esophagus. Marker displacement was greatest in the vertical dimension, intermediate in posteroanterior dimension, and smallest in mediolateral dimension. Vertical displacement was greater for the PES marker than for larynx, hyoid bone, or oropharynx markers (p < .001), so that the pharynx shortened significantly during each swallow. Marker displacement was unaffected by bolus volume. CONCLUSIONS: The pharyngeal wall shortened during swallowing. The mechanism for PES elevation may differ from that of laryngeal elevation. Shortening of the pharynx may be produced by contraction of the pharyngeal suspensory muscles and traction on the larynx by suprahyoid muscles.

Adult↗

PubMed2000

Evaluation of a new enzyme immunoassay for hepatitis C virus (HCV) core antigen with clinical sensitivity approximating that of genomic amplification of HCV RNA.

The aim of this study was to analyze the clinical performance of a new enzyme immunoassay (EIA) for hepatitis C virus (HCV) core antigen in comparison with the reverse transcription polymerase chain reaction (RT-PCR). A total of 310 patients with acute or chronic hepatitis C, and 132 HCV-negative controls were studied. Chemiluminescence EIA with monoclonal anti-HCV core antigen was used, and qualitative and quantitative commercial RT-PCRs and an in-house nested RT-PCR were performed. Compared with nested RT-PCR, the core antigen assay showed 97% sensitivity and 100% specificity in 75 patients with chronic hepatitis C and 132 controls. HCV core antigen was positive in 16 (94%) of 17 patients with acute hepatitis C at initial consultation. In 3 persons prospectively followed, core antigen was detected in the first available (1-3 weeks) post-transfusion sample. In 167 anti-HCV-positive individuals, 129 (77%) were viremic; core antigen was detected in 126 (98%) compared with 129 (100%) for nested RT-PCR and 121 (94%) for the commercial RT-PCR. In 48 patients with chronic hepatitis C treated with interferon alfa, the concentration of core antigen before treatment was significantly (P <.002) lower in patients with sustained response than in nonresponders. All responders had a sustained loss of core antigen, whereas all nonresponders remained core antigen positive. The concentrations of HCV core antigen and HCV RNA correlated significantly (n = 48, r =.627, P <.001). In conclusion, the HCV core antigen assay is useful for the diagnosis of acute and chronic hepatitis C, and for predicting and monitoring the effect of interferon alfa treatment.

Acute Disease↗

PubMed2000

Viscoelastic properties of the human temporomandibular joint disc in patients with internal derangement.

PURPOSE: This study investigated the viscoelastic properties of human temporomandibular joint (TMJ) discs in patients with severe internal derangement (ID). PATIENTS AND METHODS: TMJ discs obtained from 5 patients with severe TMJ internal derangement were analyzed. Normal discs derived from 2 fresh cadavers and 4 patients without ID served as the controls. The viscoelastic responses of the discs to tensile forces were evaluated by means of stress-strain analyses. RESULTS: The discs in both groups exhibited a nonlinear stress-strain relationship that was represented by a power function of the strain. However, after stress relaxation, the ID discs were likely to exhibit a linear stress-strain relationship. The instantaneous elastic moduli were almost the same in both discs, but the relaxed elastic modulus of the ID discs was significantly greater than that of the controls in lower strain range of less than 2%. CONCLUSIONS: ID discs are more rigid than normal discs. These findings suggest that the changes in viscoelastic property of the discs in patients with ID are somewhat different from those that occur with aging.

Adult↗

PubMed2000

An adult case of TMJ osteoarthrosis treated with splint therapy and the subsequent orthodontic occlusal reconstruction: adaptive change of the condyle during the treatment.

This article reports treatment for a 21-year 11-month old female patient with severe osteoarthrosis of the TMJ with a special reference to adaptive changes of the condyle during the treatment. She had severe open bite with a Class II molar relationship; she had limited mouth opening, TMJ sounds, pain, and tinnitus. Lateral tomograms showed flattening and deep erosion on the left condyle, and an MRI revealed anterior disk displacement without reduction. By manipulation and splint therapy, TMJ pain and tinnitus were eliminated, then orthodontic treatment was initiated, maintaining the splint-induced position of the condyles. After 2 years of orthodontic treatment with a multibracket appliance, an acceptable occlusion was achieved with a Class I molar relationship. On lateral tomograms after treatment, bony deformation of the left condyle disappeared and adaptive remodeling was recognized with a uniform joint space in the left TMJ. However, repositioning of the disk was not achieved. Adaptive changes or functional remodeling experienced in this patient may be due to stable occlusion, uniform joint space, and the consequent biomechanical equilibrium in the TMJ.

Adaptation, Physiological↗