Biomedical subjects

E Tanaka

Publications and source records attributed to E Tanaka.

At least 73 records · Page 4Linked to original sources

PubMed2001

In vivo measurement of the elastic modulus of the human periodontal ligament.

The present study was designated to determine the elastic properties of the periodontal ligament (PDL) in human subjects. A maxillary central incisor was experimentally translated so that stress or strain could be uniformly distributed in the PDL by applying a single force passing through the center of resistance. Displacements were measured under different magnitudes of load using a magnet-magnetic sensing system. From the load-displacement relations, Young's modulus of the PDL was calculated. The values determined were approximately 0.12 MPa under load ranging from 0 to 0.5 N, 0.25 MPa within the range of 0.5-1.0 N, 0.44 MPa under load 1.0-1.5 N, and between 0.69 and 0.96 MPa with 1.5-2.0 N. The values of Young's moduli increased almost exponentially with the increment of load due to a non-linear elasticity of the PDL.

Adult↗

PubMed2001

Magnetic resonance imaging in hemifacial hyperplasia.

We describe a case of hemifacial hyperplasia due to a combination of lipoma and lipomatosis. The contribution of MRI to the diagnosis of hemifacial hyperplasia and to monitoring growth and development in this condition is demonstrated.

Anatomy, Cross-Sectional↗

PubMed2001

Reduction of the hypocone of the maxillary first molar and Class III malocclusion.

This study was conducted to examine the incidence of evolutionary changes of the maxillary molars in orthodontic patients and to investigate the association of this event with craniofacial growth. Among 4,892 Japanese patients treated at the orthodontic clinic of Hiroshima University Dental Hospital, 59 patients presented with a defect of the distolingual cusp of the maxillary first molar. They consisted of 52 female patients and seven male patients with a mean age of 14.7 years. Eruption of the maxillary first and second molars was delayed and the third molar was congenitally missing in all of these patients. Thirty-seven patients exhibited Class III malocclusion (Class III evolution group). The Z scores of cephalometric measurements were compared between the Class III evolution group and the Class III control group. The latter group consisted of 37 Class III subjects with no evolutionary dental anomalies and no orthodontic history. The tooth developmental score (TDS) for each age at the initial record was compared with Nolla's standard tooth developmental score (STDS) for equivalent ages using paired t-tests. The Z scores for Ptm'-A and Ar-A were significantly smaller in the Class III evolutionary group than in the Class III control group (P < .05). The TDS for the maxillary first and second molars were significantly smaller than the STDS for these molars (P < .01). The TDS for the maxillary second molar was significantly larger than the STDS for the maxillary third molar (P < .01). This study revealed that an evolution change of the maxillary molar is more common (P < .05) in female patients than in male patients, is more frequent (P < .05) in subjects with Class III malocclusion, and is related to the anteroposterior undergrowth of the maxilla.

Adaptation, Biological↗

PubMed2001

Domain-domain interactions of HtpG, an Escherichia coli homologue of eukaryotic HSP90 molecular chaperone.

In the present study, we investigated the domain structure and domain-domain interactions of HtpG, an Escherichia coli homologue of eukaryotic HSP90. Limited proteolysis of recombinant HtpG, revealed three major tryptic sites, i.e. Arg7-Gly8, Arg336-Glu337 and Lys552-Leu553, of which the latter two were located at the positions equivalent to the major cleavage sites of human HSP90alpha. A similar pattern was obtained by papain treatment under nondenaturing conditions but not under denaturing conditions. Thus, HtpG consists of three domains, i.e. Domain A, Met1-Arg336; domain B, Glu337-Lys552; and domain C, Leu553-Ser624, as does HSP90. The domains of HtpG were expressed and their interactions were estimated on polyacrylamide gel electrophoresis under nondenaturing conditions. As a result, two kinds of domain-domain interactions were revealed: domain B interaction with domain A of the same polypeptide and domain C of one partner with domain B of the other in the dimer. Domain B could be structurally and functionally divided into two subdomains, the N-terminal two-thirds (subdomain BI) that interacted with domain A and the C-terminal one-third (subdomain BII) that interacted with domain C. The C-terminal two-thirds of domain A, i.e. Asp116-Arg336, were sufficient for the binding to domain B. We finally propose the domain organization of an HtpG dimer.

Amino Acid Sequence↗

PubMed2001

Liberation of the intramolecular interaction as the mechanism of heat-induced activation of HSP90 molecular chaperone.

The molecular chaperone function of HSP90 is activated under heat-stress conditions. In the present study, we investigated the role of the interactions in the heat-induced activation of HSP90 molecular chaperone. The preceding paper demonstrated two domain-domain interactions of HtpG, an Escherichia coli homologue of mammalian HSP90, i.e. an intra-molecular interaction between the N-terminal and middle domains and an intermolecular one between the middle and C-terminal domains. A bacterial two-hybrid system revealed that the two interactions also existed in human HSP90alpha. Partners of the interaction between the N-terminal and middle domains of human HSP90alpha could, but those between the middle and C-terminal domains could not, be replaced by the domains of HtpG. Thus, the interface between the N-terminal and middle domains is essentially unvaried from bacterial to human members of the HSP90-family proteins. The citrate synthase-binding activity of HtpG at an elevated temperature was solely localized in the N-terminal domain, but HSP90alpha possessed two sites in the N-terminal and other domains. The citrate-synthase-binding activity of the N-terminal domain was suppressed by the association of the middle domain. The complex between the N-terminal and middle domains is labile at elevated temperatures, but the other is stable even at 70 degrees C. Taken together, we propose the liberation of the N-terminal client-binding domain from the middle suppressor domain is involved in the temperature-dependent activation mechanism of HSP90 molecular chaperone.

Animals↗

PubMed2001

Effect of oestrogen on Mycobacterium avium complex pulmonary infection in mice.

The purpose of the present study was to elucidate the role of oestrogen in the pathogenesis of Mycobacterium avium complex (MAC) pulmonary disease, which occurs most frequently in postmenopausal women. The study was carried out in a murine infectious model using ovariectomized DBA/2 female mice. Infection with MAC was established by intratracheal administration of bacilli. In some experiments, ovariectomized mice were treated with exogenous 17 beta-estradiol (E2). The number of bacilli in the lungs of infected mice which received ovariectomy was significantly larger than that in the lungs of sham-operated control mice, and treatment of ovariectomized mice with exogenous E2 restored the burden of bacilli to the same level as that in the sham-operated control mice. We next examined the effect of E2 in vitro using bone marrow-derived macrophages obtained from DBA/2 female mice. The macrophages showed bacteriostatic activity against MAC after treatment with interferon-gamma (IFN-gamma) and this activity was further enhanced by the exogenous addition of E2 to the culture medium. In parallel with these findings, E2 augmented the production of reactive nitrogen intermediates (RNI) by macrophages pretreated with IFN-gamma and stimulated with MAC, as shown by evaluating nitrite production and inducible nitric oxide synthase mRNA expression. These findings taken together suggest that absence of endogenous oestrogen appears to be responsible for the development of MAC pulmonary disease in this mouse model and that the enhancement by E2 of anti-MAC activity of murine macrophages induced through increased RNI production may play some role in resistance to MAC infection.

Animals↗

PubMed2001

The clinical importance of the trimethadione tolerance test as a method for quantitative assessment of hepatic functional reserve in patients with biliary atresia.

BACKGROUND: The trimethadione (TMO) tolerance test was performed to evaluate its usefulness in the assessment of hepatic functional reserve in patients with biliary atresia. METHOD: Nineteen patients with biliary atresia after hepatic portoenterostomy (age range: 2 months to 25 years; sex: 6 males and 13 females) were studied. The study was performed in the morning after a 12-h fast. TMO was given orally, at a dose of 4 mg/kg, with 5 mL of 5% glucose 2 h before breakfast. Blood samples (0.5 mL) were collected to determine serum TMO and dimethadione (DMO), a metabolite of TMO, levels 4 h after the administration of TMO. TMO and DMO were measured by a gas-liquid chromatographic method. RESULTS: A higher total bilirubin level (over 1 mg/dL) in patients with jaundice was reflected in the smaller serum DMO/TMO ratio 4 h after the oral administration of TMO. In addition, these patients with total bilirubin levels of 1 mg/dL or less had a significantly lower DMO/TMO ratio than the control group (healthy subjects). The serum DMO/TMO ratio showed a close correlation with the Child-Pugh score, which is used for overall evaluation of severity of cirrhosis and Mayo risk scores for primary biliary cirrhosis in adults (0.856, P < 0.01 and 0.788, P < 0.01, respectively). The TMO tolerance test shows the benefit of performing a relatively early test of dynamic liver function to evaluate hepatic functional reserve in pre- and post-operative biliary atresia patients.

Administration, Oral↗

PubMed2001

Influences of occlusal and skeletal discrepancies on biomechanical environment in the TMJ during maximum clenching: an analytic approach with the finite element method.

The purpose of this study was to investigate the influences of occlusal and skeletal discrepancies on temporomandibular joint (TMJ) stresses during maximum clenching. A three-dimensional (3-D) finite element model of the mandible including the TMJ was developed as a standard model. Furthermore, nine modified models were established; one dentoalveolar open bite model and eight skeletal open bite models with varying gonial angles or mandibular plane angles (FMAs). For the dentoalveolar open bite model, the TMJ stresses were larger than those for the standard model, although the distribution pattern was not essentially varied. In the skeletal open bite model with greater gonial angle or FMA, the TMJ stresses were significantly larger than those in the dentoalveolar open bite model. In conclusion, the TMJ stress was affected by occlusal and/or skeletal discrepancies, if coexisted in particular, indicating the association with degenerative changes of the TMJ components.

Biomechanical Phenomena↗

PubMed2001

Epidemiology of suicidal ideation and help-seeking behaviors among the elderly in Japan.

This study offers an analysis of the elderly (over 65 years of age) among a general community population in terms of the percentages of: (i) persons with recurring thoughts of death and/or of committing suicide, and (ii) people who have consulted others, including medical professionals, with regard to these problems. Among 433 elderly over the age of 65 in one community in a town in Aomori Prefecture, 358 agreed to participate in the project. Forty-four participants (12.3%) responded that they had either 'thoughts of death' or 'thoughts of suicide', and these thoughts had continued for more than 2 weeks in 12 participants (3.4%). Only 15 of the 44 suicidal elderly responded that they had consulted someone about their problems. Although there are many elderly people exhibiting a subclinical depressive state with recurring thoughts of death or thoughts of suicide, the number of people who consult family members, professionals, or others is very low. This suggests the importance of community networking through educational activities so that people can more readily talk to and support one another.

Aged↗

PubMed2001

Geographic distribution of hepatitis B virus (HBV) genotype in patients with chronic HBV infection in Japan.

The geographic distribution of hepatitis B virus (HBV) genotypes in Japan and its clinical relevance are poorly understood. We studied 731 Japanese patients with chronic HBV infection. HBV genotype was determined by the restriction fragment length polymorphism (RFLP) method after polymerase chain reaction (PCR). Of the 720 patients with positive PCR, 12 (1.7%) were HBV genotype A, 88 (12.2%) were genotype B, 610 (84.7%) were genotype C, 3 (0.4%) were genotype D, and 7 (1.0%) were of mixed genotype. Over 94% of patients on the Japanese mainland had genotype C, while 60% of the patients on Okinawa, the most southern islands, and 22.9% in the Tohoku area, the northern part of the mainland, harbored genotype B. Compared with genotype C patients, genotype B patients were older (53.6 to 42.2 years; P <.01), had a lower rate of positive hepatitis B e antigen (HBeAg) (18.4% to 50.6%; P <.01), and a lower level of serum HBV DNA (5.02 to 5.87 log genome equivalents (LGE)/mL; P <.01). The mean age of the genotype B patients with hepatocellular carcinoma was 70.1 +/- 9.2 years, compared with 55.2 +/- 9.7 of genotype C patients (P <.01). These results indicate that genotypes C and B are predominant in Japan, and there are significant differences in geographic distribution and clinical characteristics among the patients with the different genotypes.

Adult↗

PubMed2001

Stress analysis in the TMJ during jaw opening by use of a three-dimensional finite element model based on magnetic resonance images.

This study was designed to investigate temporomandibular joint (TMJ) stress distribution during mouth opening using a finite element (FE) model of an individual TMJ based on magnetic resonance (MR) images. A dry skull with a silicon disk was used to test the three-dimensional reconstruction procedure, and showed enough accuracy and reproducibility in linear dimensions and disk volume for the following FE modelling for stress analysis in the TMJ. From an individual FE analysis of a normal subject, relatively high stresses were observed in the anterior and posterior regions of the disk during mouth opening, and furthermore, the superior boundary contacting with the glenoid fossa exhibited lower stresses than those on the inferior boundary facing the condyle. During transmission of stress through the disk, mechanical stress may be reduced by the stress redistribution function of the disk.

Adult↗

PubMed2001

Plasma lidocaine concentrations during continuous thoracic epidural anesthesia after clonidine premedication in children.

UNLABELLED: There is no report concerning oral clonidine's effects on epidural lidocaine in children. Therefore, we performed a study to assess the concentrations of plasma lidocaine and its major metabolite (monoethylglycinexylidide [MEGX]) in children receiving continuous thoracic epidural anesthesia after oral clonidine premedication. Ten pediatric patients, aged 1-9 yr, were randomly allocated to the Control or Clonidine 4 microg/kg group (n = 5 each). Anesthesia was induced and maintained with sevoflurane in oxygen and air (FIO2 40%). Epidural puncture and tubing were carefully performed at the Th11-12 intervertebral space. An initial dose of 1% lidocaine (5 mg/kg) was injected through a catheter into the epidural space, followed by 2.5 mg x kg(-1) x h(-1). Plasma concentrations of lidocaine and MEGX were measured at 15 min, 30 min, and every 60 min for 4 h after the initiation of continuous epidural injection. The concentrations of lidocaine and MEGX were measured using high-pressure liquid chromatography with ultraviolet detection. Hemodynamic variables were similar between members of the Control and Clonidine groups during anesthesia. The Clonidine group showed significantly smaller lidocaine concentrations (p < 0.05) and the concentration of MEGX tended to be smaller in the plasma of the Clonidine group for the initial 4 h after the initiation of epidural infusion. In conclusion, oral clonidine preanesthetic medication at a dose of 4 microg/kg decreases plasma lidocaine concentration in children. IMPLICATIONS: Oral clonidine decreases the plasma lidocaine concentration in children. Our finding may have clinical implications in patients receiving continuous epidural anesthesia. Additionally, perhaps an additional margin of safety regarding lidocaine toxicity is gained through the use of oral clonidine in children who will receive epidural lidocaine.

Administration, Oral↗

PubMed2001

Mechanisms underlying the depression of evoked fast EPSCs following in vitro ischemia in rat hippocampal CA1 neurons.

The mechanisms underlying the depression of evoked fast excitatory postsynaptic currents (EPSCs) following superfusion with medium deprived of oxygen and glucose (in vitro ischemia) for a 4-min period in hippocampal CA1 neurons were investigated in rat brain slices. The amplitude of evoked fast EPSCs decreased by 85 +/- 7% of the control 4 min after the onset of in vitro ischemia. In contrast, the exogenous glutamate-induced inward currents were augmented, while the spontaneous miniature EPSCs obtained in the presence of tetrodotoxin (TTX, 1 microM) did not change in amplitude during in vitro ischemia. In a normoxic medium, a pair of fast EPSCs was elicited by paired-pulse stimulation (40-ms interval), and the amplitude of the second fast EPSC increased to 156 +/- 24% of the first EPSC amplitude. The ratio of paired-pulse facilitation (PPF ratio) increased during in vitro ischemia. Pretreatment of the slices with adenosine 1 (A1) receptor antagonist, 8-cyclopenthyltheophiline (8-CPT) antagonized the depression of the fast EPSCs, in a concentration-dependent manner: in the presence of 8-CPT (1-10 microM), the amplitude of the fast EPSCs decreased by only 20% of the control during in vitro ischemia. In addition, 8-CPT antagonized the enhancement of the PPF ratio during in vitro ischemia. A pair of presynaptic volleys and excitatory postsynaptic field potentials (fEPSPs) were extracellularly recorded in a proximal part of the stratum radiatum in the CA1 region. The PPF ratio for the fEPSPs also increased during in vitro ischemia. On the other hand, the amplitudes of the first and second presynaptic volley, which were abolished by TTX (0.5 microM), did not change during in vitro ischemia. The maximal slope of the Ca(2+)-dependent action potential of the CA3 neurons, which were evoked in the presence of 8-CPT (1 microM), nifedipine (20 microM), TTX (0.5 microM), and tetraethyl ammonium chloride (20 mM), decreased by 12 +/- 6% of the control 4 min after the onset of in vitro ischemia. These results suggest that in vitro ischemia depresses the evoked fast EPSCs mainly via the presynaptic A1 receptors, and the remaining 8-CPT-resistant depression of the fast EPSCs is probably due to a direct inhibition of the Ca(2+) influx to the axon terminals.

Animals↗

PubMed2001

Labeling effect of Seishin-bunretsu-byou, the Japanese translation for schizophrenia: an argument for relabeling.

Stigma attached to individuals with schizophrenia may be derived from its diagnostic label. Two forms of a questionnaire were distributed to 189 Japanese university students. Each questionnaire contains case vignettes of schizophrenia and major depression. In one form, the students were told at the close of each vignette the diagnostic label assigned to that case (the label group) whereas in another form, they were not done so (the control group). The students were also asked to rate negative image of the case in four items each. The label group was significantly higher than the control group in three of the four negative image items for the vignette of schizophrenia. They did not differ in any of the negative image items for the vignette of depression. This suggests that the label of schizophrenia (the Japanese translation Seishin-bunretsu-byou) has stigmatizing effect. We discussed these findings in the light of the implications of a relabeling, and argued for a change of name.

Adult↗

PubMed2001

Chlorzoxazone: a probe drug the metabolism of which can be used to monitor one-point blood sampling in the carbon tetrachloride-intoxicated rat.

In this study, we have carried out an investigation to determine if chlorzoxazone (CZX) is a suitable probe drug for predicting hepatic injury in carbon tetrachloride (CCl4)-intoxicated rats. The animals received oral doses of CCl4 (0.25, 0.5 and 1 ml/kg) 24 h prior to intraperitoneal administration of CZX. The total CYP and CYP2E1 content, as well as the aniline and CZX hydroxylase activity (Vmax and CLint), was reduced depending on the dose of CCl4 administered. At the highest concentration (128 mM) of diethyldithiocarbamate, a specific inhibitor of CYP2E1, the production of 6-hydroxychlorzoxazone (HCZX) in microsomes from CCl4-treated rats was reduced by about 85%. The IC50 value in microsomes from CCl4-treated rats was between 3 and 5 microM. The production of HCZX and the activity of aniline hydroxylase in CCl4-treated rats correlated with the amount of rat CYP2E1 protein (r=0.881, P<0.001 and r=0.822, P<0.001, respectively). The elimination of CZX by CCl4-treated rats was reduced and the HCXZ production in the CCl4-treated group was less than that in the olive oil-treated control group. The correlations between the intrinsic clearance [CLint: Vmax/Km) in vitro and the total body clearance (CLtot) of CZX hydroxylation and the elimination half-life (t1/2) of CZX in vivo in CCl4-treated rats were high (r=0.839, P<0.001 and r= -0.828, P<0.001, respectively). In addition, the metabolic plasma HCZX/CZX ratio did not require multiple blood sampling and, 2 h after CZX administration in vivo, there was also a high correlation with the CLint (Vmax/Km) in vitro (r= -0.909, P<0.01). In conclusion, these results from this study demonstrate that CZX is a good probe for monitoring the inhibition of metabolism in rats due to CCl4 treatment.

Aniline Hydroxylase↗

PubMed2001

Hair analysis for pharmaceutical drugs. I. Effective extraction and determination of phenobarbital, phenytoin and their major metabolites in rat and human hair.

In order to establish an analytical method for the determination of phenobarbital (PB), phenytoin (PPH) and their hydroxylated metabolites in hair, animal model experiments were performed. Five male dark-agouti pigmented rats, aged 5 weeks, were intraperitoneally and orally administered PB or PPH independently at 25 mg/kg once a day for 5 successive days. The growing back hair was collected 15d after the first administration. Four typical extraction methods, using NH4OH-methanol-acetone, TFA-methanol-acetone, 1M sodium hydroxide and proteinase K, were evaluated using the rat hair samples containing PB or PPH. Methanol-acetone-NH4OH (10: 10: 1) was the best extraction method from all aspects, such as high extraction efficiency and low noise. The analytes in the extract were methylated in acetonitrile with 20% tetramethylammonium hydroxide and methyliodide at 70 degrees C for 10 min. After purification with Bond Elut Certify, the methylated products were analyzed by GC-MS. From rat hair, PB, p-hydroxy PB, PPH and p-hydroxy PPH were detected at average concentrations of 26.9, trace, 4.2 and 0.4 ng/mg with an intraperitoneal (i.p.) injection, and at 30.9, trace, 4.0 and 0.4 ng/mg with oral administration, respectively. There was little difference in hair concentrations between i.p. injection and oral administration. This method was applied to the head hair of two patients who orally took toxic amounts of PB and two volunteers who orally took 100 mg of PPH daily for 5 d. The hair concentrations of PB in the two patients were 16.2 and 14.7 ng/mg, and those of PPH in the two volunteers were 3.3 and 0.1 ng/mg.

Adult↗

PubMed2001

Renal cortical retention on delayed CT and nephropathy following transcatheter arterial chemoembolisation.

The aim of this study was to examine the relationship between renal cortical retention on delayed CT and contrast medium-associated and/or transarterial chemoembolisation (TACE)-associated nephropathy following TACE. The authors reviewed the findings on 180 treatments in 121 patients with normal serum creatinine levels who underwent TACE for liver tumours. Nephropathy was defined as an increase in the creatinine level of greater than 0.5 mg x dl(-1) (44 micromol x l(-1)) and greater than 25% on days 1, 3, 7 or 14 post TACE. Renal cortical retention was recognized when CT values for the renal cortex showed either mild renal cortical retention (CT value >50) or severe renal cortical retention (CT value >100). There was evidence of renal cortical retention in 81 (45%) cases and of nephropathy in 11 (6%) cases. Only 2% of patients without renal cortical retention showed nephropathy, whereas 11% of those with renal cortical retention showed nephropathy (p=0.02). Stepwise selection using a multivariate logistic regression model showed renal cortical retention and gender to be significant factors for nephropathy following TACE. In conclusion, renal cortical retention is a useful predicator for nephropathy following TACE. Delayed CT could be used not only for assessment of lipiodol retention but also for predicting nephropathy.

Adult↗

PubMed2001

Solitary true cyst of the pancreas in an adult: report of a case.

BACKGROUND: Solitary true cyst of the pancreas is rare in adults, and the differential diagnosis of cystic lesions of the pancreas is challenging. AIM OF THE STUDY: To describe a solitary true cyst of the pancreas in an adult and discuss the differential diagnosis. METHODS: A 50 yr old woman presented with a mass lesion in the right upper quadrant of the abdomen. Abdominal computed tomography showed a cystic lesion, with a maximum diameter of 12 cm, between the inferior surface of the liver and the ascending colon. The cyst was homogenous and had smooth edges. On magnetic resonance imaging, a unilocular cyst was seen that was low intensity on T1-weighted images and very high intensity on T2-weighted images. No connection between the cyst and the pancreatic ductal system was demonstrated on endoscopic retrograde cholangiopancreatography. Laparotomy was performed with a presumptive diagnosis of cystic tumor of the pancreas. RESULTS: On pathologic examination, the cyst was serous and was lined with a single layer of normal cuboidal epithelium that was periodic acid Schiff stain negative. Meticulous examination failed to identify honeycomb-like microcysts characteristic of serous cystadenoma. The final diagnosis was a solitary true cyst of the pancreas. CONCLUSION: The differential diagnosis of solitary true cyst from other cystic lesion of the pancreas usually is based on histology. Particular care must be taken to distinguish this lesion from macrocystic serous cystadenoma.

Diagnosis, Differential↗