Biomedical subjects

Eiji Tanaka

Publications and source records attributed to Eiji Tanaka.

At least 19 recordsLinked to original sources

PubMed2003

The proteoglycan contents of the temporomandibular joint disc influence its dynamic viscoelastic properties.

The collagen fibers and proteoglycans in the disc of temporomandibular joint provide resistance to various loadings. Thus far, however, the role of the proteoglycans in determining the viscoelastic properties of the disc has not been investigated. In the present study the hypothesis was tested that the viscoelastic behavior of the disc decreases by the removal of proteoglycans. In 32 bovine discs, dynamic tensile tests with a wide range of frequencies were performed. Before testing, specimens were treated with different concentrations of alpha-amylase to remove proteoglycans. As the frequency increased from 0.1 to 100 Hz, the disc became more viscoelastic. Increasing the concentration of alpha-amylase significantly decreased its viscoelasticity. It was concluded that proteoglycans play an important role in determining the viscoelastic properties of the disc and, therefore, give the disc a greater capacity for distributing and reducing stresses.

Animals↗

PubMed2003

A case-control study for early prediction of hepatitis B e antigen seroconversion by hepatitis B virus DNA levels and mutations in the precore region and core promoter.

Factors influencing and predictive of seroconversion from hepatitis B e antigen (HBeAg) to antibody (anti-HBe) were sought in a case-control study of 61 patients with chronic hepatitis B who had been observed from 5 years before to 1 year after seroconversion, and 32 patients who did not seroconvert during the entire 6-year period. Almost all of the patients (96%) were infected with HBV genotype C. HBV DNA levels began to decrease 3 years before seroconversion in the seroconverters, while they remained high in the non-converters. The frequency of precore mutation and the loss of HBeAg (A1896) started to increase 1 year before in the converters, and became significantly higher at seroconversion (23 vs. 3%, P = 0.030) than that in the non-converters. Double mutation in the core promoter (T1762/A1764) was more common in the seroconverters than in the non-converters 5 years before seroconversion (48 vs. 28%), and became significantly more frequent at seroconversion (65 vs. 41%, P = 0.046). Seroconversion occurred in 75% of the patients with at least HBV DNA levels <5.5 logarithmic equivalents/mL; precore mutation in 20% or more of HBV DNA; or core promoter mutation. Seroconversion occurred in 50% of those patients within 1 year, 88% within 2 years, and 93% within 5 years. These results indicate that a decrease in HBV DNA levels and mutations in the precore region and the core promoter were associated significantly and complementarily with seroconversion, and each of them or a combination thereof was predictive of seroconversion years ahead.

Adult↗

PubMed2003

Factors predisposing to the occurrence of cryoglobulinemia in two cohorts of Egyptian and Japanese patients with chronic hepatitis C infection: ethnic and genotypic influence.

The association between cryoglobulinemia and hepatitis C virus (HCV) infection has been reported. However, the factors underlying its wide variation of occurrence have not yet been well identified. To investigate this, cryoglobulinemia was studied in four cohorts of Egyptian and Japanese patients. Fifty Egyptian patients with chronic hepatitis C, infected with genotype 4 (the predominant HCV genotype in Egypt), were compared with 50 age- and sex-matched Japanese patients, infected with HCV genotype 1b (the predominant HCV genotype in Japan). Thirty-two Egyptian and 30 age- and sex-matched Japanese patients with chronic hepatitis B were included as controls. All patients were noncirrhotic. Antinuclear antibody (ANA), immunoglobulins (Ig), and cryoglubulins were assessed. Results showed a significantly higher prevalence of cryoglobulinemia in chronic hepatitis C Japanese genotype 1b (40%) as compared with Egyptian genotype 4 (14%), P = 0.003, while no difference was found between Japanese (17%) and Egyptian chronic hepatitis B controls (13%). Symptomatic cryoglobulinemia was more prevalent in the Japanese than in the Egyptian chronic hepatitis C group (10% vs. 4%), but the difference was not statistically significant. Univariate analysis showed no association between cryoglobulinemia and either age, sex, alanine aminotransferase level, or HCV viral load in Japanese or Egyptian patients, while the mean IgM level was significantly higher in the cryoglobulin-positive than in the cryoglobulin-negative chronic hepatitis C patients in each group (P = 0.003 and 0.017, respectively). Cryoglobulinemia was found to be significantly associated with both high IgG level (P = 0.020), and positive ANA (P < 0.001) in Japanese patients with chronic hepatitis C, genotype 1b but not in Egyptians with genotype 4. Multivariate analysis showed that the only factors predisposing to cryoglobulinemia were Japanese ethnicity with HCV genotype1b (P = 0.002, OR = 2.56), high IgM level of >245 mg/dl (P = 0.018, OR = 2.05) and female gender (P = 0.040, OR = 1/0.66). In conclusion, cryoglobulinemia is prevalent in Japanese patients with chronic hepatitis C infected with genotype 1b, but cryoglobulinemia is not common in Egyptians with HCV genotype 4. Although it was not possible to evaluate ethnicity and HCV genotype separately in this study, HCV genotype 1b appears to predispose more to cryoglobulinemia than does genotype 4. Female gender and high serum IgM level were also related.

Asian People↗

PubMed2003

Risk factors contributing to early and late phase intrahepatic recurrence of hepatocellular carcinoma after hepatectomy.

BACKGROUND/AIMS: We conducted a retrospective cohort study to investigate factors to early and late phase recurrence of hepatocellular carcinoma (HCC). METHODS: The study population consisted of 249 patients including 157 with cirrhosis who underwent hepatectomy for HCC. The endpoint was time-to-recurrence. Using a Cox regression model, factors to early and late phase recurrences were investigated censoring recurrence-free patients at the 2-year time point and in patients without recurrence at 2 years. RESULTS: Actuarial probability of overall recurrence at 1, 3, and 5 years were 0.301, 0.623, and 0.790, respectively, with a median follow-up of 624 days. Early recurrence was observed in 123 out of 249 patients; while late recurrence was found in 61 out of 113 patients. Factors to early recurrence were as follows: non-anatomical resection, presence of microscopic vascular invasion, and serum alpha-fetoprotein level >or=32 ng/ml. Those contributing to late phase recurrence were higher grade of hepatitis activity, multiple tumors, and gross tumor classification. CONCLUSIONS: Variables associated with metastatic recurrence were factors to early phase recurrence; whereas those related with elevated carcinogenesis contributed to late phase recurrence, thus providing an epidemiological evidence that different mechanisms, i.e. metastasis and de novo, are involved in intrahepatic recurrence after hepatectomy for HCC.

Adult↗

PubMed2003

Analysis of the genotype-determining region of hepatitis A viral RNA in relation to disease severities.

Although hepatitis A is still a considerable problem in Japan, correlation of genomic differences of hepatitis A virus (HAV) and the clinical status of hepatitis A has not been studied. To examine whether the HAV genotype is associated with the disease severity, we analyzed the HAV genotype-determining region in sera from patients with hepatitis A of various clinical degrees. Serum samples from 47 Japanese patients with sporadic hepatitis A from 4 different areas in Japan, including 8 with fulminant hepatitis, 11 with severe acute hepatitis (AHs), and 28 with AHs, were examined for HAV RNA. The 168 base pair sequence of the genotype-determining region, which is located at the VP1/2A junction, was amplified by reverse transcription-polymerase chain reaction, and the nucleotide sequence was determined by direct sequencing. By comparing sequences for VP1/2A, we determined that 44 of 47 cases examined were of subgenotype IA, two were of subgenotype IB, and one was of subgenotype IIIA. With respect to subgenotype IA strains, individuals who were infected between 1990 and 1996 tended to show similar sequences, whereas those infected between 1997 and 1999 showed sequences slightly different from those of the 1990-1996 cases. There were no apparent associations between disease severity and sequences of the genotype-determining region. Hepatitis A of our study was caused by a variety of subgenotype IA strains, consistent with the sporadic spread of infection. Disease severity was not associated with the nucleotide sequence of the HAV genotype-determining region.

Journal Article↗

PubMed2003

Impulsive compression influences the viscous behavior of porcine temporomandibular joint disc.

Traumatic joint injury is known to produce osteoarthritic degeneration in the temporomandibular joint (TMJ). However, little information, is available on its possible effect on the dynamic viscoelastic behavior of the disc. In the present study, impulsive compression was applied to the disc as a model for traumatic joint injury. This was tested in 32 porcine discs. Prior to a dynamic tensile test, impulsive compression with strain rates of 0.01, 0.1 and 1 s(-1) to a final strain of 30% was applied to these discs. Tensile stress was applied in the antero-posterior direction with a wide range of frequencies (0.1-100 Hz). The dynamic E-moduli increased as the loading frequency increased. The dynamic viscosity and elasticity decreased with an increase of strain rate, although the effect on viscosity was greater than on elasticity. The results suggest that strain rate and subsequent peak stress of impulsive compression affect primarily the dynamic viscosity of the disc, and that impulsive compression at high strain rates reduces the resistance of the TMJ disc to stress, resulting in permanent disc deformation and perforation.

Animals↗

PubMed2003

Dynamic compressive properties of porcine temporomandibular joint disc.

This study aimed to evaluate the effect of the strain frequency and amplitude on the compressive properties of the porcine temporomandibular joint disc and to determine the time-dependent changes associated with energy dissipation. Seven discs were used for compressive cycle tests, including various frequencies and magnitudes of compressive strain. Each experiment consisted of 25 cycles of loading and unloading. Hysteresis and the instantaneous and steady moduli were calculated. All specimens showed a clear hysteresis and repeatable stress-strain relationships within 19 cycles. The hysteresis at the initial cycle ranged between 35% and 62%, and gradually decreased in subsequent cycles. The instantaneous modulus became larger when the strain frequency and the strain amplitude increased. The steady modulus was approximately one-third of the instantaneous one. It was concluded that the disc has an energy-dissipating function during dynamic compression.

Analysis of Variance↗

PubMed2003

Influence of friction at articular surfaces of the temporomandibular joint on stresses in the articular disk: a theoretical approach with the finite element method.

The present study was designed to assess stress and displacement of the temporomandibular joint (TMJ) disk during jaw opening with different frictional coefficients (micro) from 0.0001 to 0.5 at the TMJ disk and bony component interfaces using three-dimensional finite element (FE) models of individual TMJs based on magnetic resonance (MR) images. An asymptomatic female volunteer and a female patient with anterior disk displacement without reduction were selected, and serial sagittal and frontal slices of their MR images were used for the TMJ reconstruction procedure. The condylar movement was recorded during jaw opening by a Gnatho-hexagraph and used as the loading condition for the subsequent stress analysis of the model. In the asymptomatic subject, relatively high von Mises stresses were observed in the anterior and lateral regions of the disk during jaw opening, and the superior boundary, contacting with the glenoid fossa, exhibited lower stresses than those on the inferior boundary facing the condyle. In the symptomatic subject, although the stress value in the disk was relatively low, the posterior connective tissue exhibited high stress throughout jaw opening. Additional increments in stress values and disk displacement were observed as the coefficient of friction increased, especially in the asymptomatic subject. It is concluded that an augmentation in the friction between the disk, glenoid fossa, and condyle produces an increment in stress and displacement of the disk.

Adult↗

PubMed2003

Clinical significance of SEN virus infection in patients on maintenance haemodialysis.

BACKGROUND: The SEN virus (SENV) has been identified as a putative new hepatitis virus. This study was conducted to clarify the clinical significance of SENV infection in patients on haemodialysis. METHODS: A total of 189 patients on maintenance haemodialysis and 60 healthy controls were enrolled. Of the 189 patients, 154 were followed up for 2 years. SENV DNA (genotypes D and H) was measured by means of polymerase chain reaction. RESULTS: SENV infection was significantly (P=0.012) more prevalent in patients on haemodialysis (38%) than in controls (22%). SENV infection was not associated with the amount of transfusion or duration of haemodialysis, while hepatitis C virus (HCV) infection was significantly associated with both of these factors. Elevation of alanine aminotransferase was significantly associated with HCV, but not with SENV viraemia. Of the 154 patients who were followed up, 63 (41%) remained negative, 34 (22%) gained positivity, 28 (18%) lost it and 29 (19%) remained positive for SENV infection. Episodes of alanine aminotransferase elevation were recorded for 3% of the patients who incurred SENV infection and this rate was similar to that observed in patients who were continuously negative for SENV infection (5%). CONCLUSIONS: SENV infection was common in patients on haemodialysis. No evidence was obtained that suggested involvement of the hepatitis virus in the pathogenicity of SENV.

Adult↗

PubMed2003

New enzyme immunoassay for detection of hepatitis B virus core antigen (HBcAg) and relation between levels of HBcAg and HBV DNA.

A new enzyme immunoassay specific for hepatitis B virus (HBV) core antigen (HBcAg) was developed. In order to detect HBcAg, specimens were pretreated with detergents to release HBcAg from the HBV virion and disassemble it to dimers, and simultaneously, the treatment inactivated anti-HBc antibodies. HBcAg detected by the assay peaked with HBV DNA in density gradient fractions of HBV-positive sera. The assay showed a wide detection range from 2 to 100,000 pg/ml. We observed no interference from anti-HBc antibody or blood components, but the assay was inhibited by very high concentrations (>1 microg/ml; corresponding to 80 signal/cutoff) of HBeAg. When the cutoff value was tentatively set at 4 pg/ml, all healthy control (HBsAg and HBV DNA negative, n = 160) and anti-hepatitis C virus-positive (n = 55) sera were identified as negative. HBcAg concentrations correlated very closely with HBV DNA (r = 0.946, n = 145) in 216 samples from 72 hepatitis B patients. In seroconversion panels, HBcAg concentrations changed in parallel with HBV DNA levels. The assay, therefore, offers a simple method for monitoring hepatitis B patients. With a series of sera during lamivudine therapy, HBV DNA levels fell sharply and the HBcAg concentration also decreased, but the change in HBcAg was smaller and more gradual. The supposed mechanism of these changes and their clinical significance are discussed.

Antibodies, Monoclonal↗

PubMed2003

Biomechanical behavior of the temporomandibular joint disc.

The temporomandibular joint (TMJ) disc consists mainly of collagen fibers and proteoglycans constrained in the interstices of the collagen fiber mesh. This construction results in a viscoelastic response of the disc to loading and enables the disc to play an important role as a stress absorber during function. The viscoelastic properties depend on the direction (tension, compression, and shear) and the type of the applied loading (static and dynamic). The compressive elastic modulus of the disc is smaller than its tensile one because the elasticity of the disc is more dependent on the collagen fibers than on the proteoglycans. When dynamic loading occurs, the disc is likely to behave less stiffly than under static loading because of the difference of fluid flow through and out of the disc during loading. In addition, the mechanical properties change as a result of various intrinsic and extrinsic factors in life such as aging, trauma, and pathology. Information about the viscoelastic behavior of the disc is required for its function to be understood and, for instance, for a suitable TMJ replacement device to be constructed. In this review, the biomechanical behavior of the disc in response to different loading conditions is discussed.

Adaptation, Physiological↗

PubMed2003

A pulmonary metastatic model of human non-small cell lung carcinoma cells that produce a neutrophil elastase-like molecule in severe combined immunodeficiency mice.

STUDY OBJECTIVES: To establish a clinically relevant animal model of pulmonary metastases of human non-small cell lung carcinoma (NSCLC) cells in severe combined immunodeficiency (SCID) mice, which can be used for repetitive investigations, so as to improve our understanding and management of the cellular and molecular mechanisms of human lung cancer metastases. METHODS AND RESULTS: SCID mice subcutaneously injected in the flank with 1 x 10(6) EBC-1 cells derived from human lung squamous cell carcinoma were killed weekly for examination until 12 weeks after tumor inoculation. The biological characteristics of implanted tumors and their metastatic foci were investigated by hematoxylin-eosin staining and immunostaining for neutrophil elastase (NE). Three weeks after ectopic implantation, EBC-1 cell lines formed a tumor at the inoculation site and grew steadily to show a plateau at 10 weeks. EBC-1 cells formed multiple metastases in the lung 7 weeks after tumor inoculation; their numbers increased steadily until 12 weeks in all mice. Immunoreactivity for NE was intense in the metastatic tumor cells. Then, to establish the primary tumor amputation/pulmonary metastasis model and to evaluate how primary tumor amputation influences the development of pulmonary metastases at the cellular and molecular level, excision was performed before (3 weeks and 5 weeks after inoculation) and after (7 weeks and 9 weeks after inoculation) formation of lung metastases. When the primary tumor was excised 3 weeks after tumor inoculation, all mice had pulmonary metastasis at 12 weeks after inoculation. Blood samples obtained at 3 weeks after tumor inoculation contained human beta-actin messenger RNA, which represents circulating tumor cells. CONCLUSION: Our NSCLC EBC-1 pulmonary metastasis model is reliable, technically simple, and predictably results in pulmonary metastasis from early hematogenous spread. This model may be useful for elucidating the mechanism of pulmonary metastasis in human lung cancer, and testing anti-metastatic efficacy of therapeutic agents in vivo.

Animals↗

PubMed2003

[Hepatitis E].

Explore the source record for details and available documents.

Animals↗

PubMed2002

Expression of c-Fos-like immunoreactive neurons in the supratrigeminal region in the rat following noxious stimulation of the orofacial tissues.

This study was conducted to investigate immunohistochemically the expression of c-Fos in neurons around the trigeminal motor nucleus following application of mechanical force to a tooth, a mechanical pinch to the tongue, and paraformaldehyde injection into the periodontal ligament and masseter muscle. Following the application of all of these stimuli except pinching the tongue, a small number of c-Fos-like immunoreactive (Fos-LI) neurons were found in the ipsilateral supratrigeminal region. c-Fos expression was also detected in numerous neurons in the superficial laminae of the subnucleus caudalis in all experimental animals. Induction of c-Fos in the subnucleus caudalis and the supratrigeminal region indicates that Fos-LI neurons in the supratrigeminal region are involved in the processing of intraoral nociceptive signals.

Animals↗

PubMed2002

Peroxisome proliferator-activated receptor gamma ligand troglitazone induces cell cycle arrest and apoptosis of hepatocellular carcinoma cell lines.

BACKGROUND: Ligand activation of peroxisome proliferator-activated receptor gamma (PPARgamma) results in the inhibition of proliferation of various cancer cells. The aim of this study is to investigate the mechanisms of cell growth inhibition of hepatocellular carcinoma (HCC) cell lines by the PPARgamma ligand, troglitazone. METHODS: Six HCC cell lines were used to study the effects of troglitazone on cell growth by 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) assay, on cell cycle by flow cytometry, and on the cell cycle-regulating factors of late G1 phase by Western blotting. Apoptosis assays were performed by flow cytometry using membrane, nuclear, cytoplasmic, and mitochondrial markers. Caspase inhibitors were used to analyze the mechanisms of apoptosis induced by troglitazone. RESULTS: Troglitazone showed a potent dose-dependent effect on the growth inhibition of all six HCC cell lines, which were suppressed to under 50% of control at the concentration of 10 micromol/L. The growth inhibition was linked to the G1 phase cell cycle arrest through the up-expression of the cyclin-dependent kinase inhibitors, p21 and p27 proteins, and the hypophosphorylation of retinoblastoma protein. Troglitazone induced apoptosis by caspase-dependent (mitchondrial transmembrane potential decrease, cleavage of poly [adenosine diphosphate ribose] polymerase, 7A6 antigen exposure, Bcl-2 decrease, and activation of caspase 3) and caspase-independent (phosphatidylserine externalization) mechanisms. CONCLUSIONS: Our data suggest that ligand activation of PPARgamma by troglitazone or modified analogs of the thiazolidinedione class of drugs is a novel target for effective therapy against HCC, because of the significant antiproliferative and programmed cell death induction capabilities demonstrated by troglitazone.

Antineoplastic Agents↗

PubMed2002

Extensive intraoperative peritoneal lavage and chemotherapy for gastric cancer patients with peritoneal free cancer cells.

The effects of extensive intraoperative peritoneal lavage (EIPL) for gastric cancer patients with peritoneal free cancer cells were investigated. This study was based on 22 consecutive patients with peritoneal free cancer cells, among 663 patients who underwent curative surgical treatment for advanced gastric cancer. The 22 patients were followed up for 2 years or until death. These patients were divided into three groups: group 1, patients with no additional intraoperative therapy (from 1989 to 1992; n = 8); group 2, patients with intraoperative intraperitoneal chemotherapy alone (from 1992 to 1995; n = 7); and group 3, patients with EIPL followed by intraoperative intraperitoneal chemotherapy (from 1996 to 1999; n = 7). Reverse transcriptase-polymerase chain reaction (RT-PCR) analysis showed that viable cancer cells were not detected after the eighth EIPL in a gastric cancer patient with numerous intraperitoneal free cancer cells. In group 3, 4 of the 7 patients survived for more than 2 years, including 3 with cancer-free status, whereas no patient survived cancer-free in groups 1 and 2. The peritoneal recurrence rates and cancer-specific 2-year survival rates in groups 1, 2, and 3 were 100%, 85.7% and 42.9%; and 0%, 14.3%, and 57.1%, respectively. The 2-year survival rate of group 3 was significantly higher than that of group 1 (P = 0.017) and that of group 2 (P = 0.025). In a subset analysis, patients with peritoneal free gastric cancer cells but no macroscopic dissemination showed a statistically significant improvement in survival those treated with EIPL compared with those not treated with EIPL.

Antineoplastic Agents↗

PubMed2002

Clinical significance of T.T. virus infection in maintenance hemodialysis patients of an endemic area for hepatitis C infection.

Clinical significance of TTV infection was analyzed in Egyptian hemodialysis (HD) patients. Forty-seven Egyptian patients on maintenance HD and 50 age-matched volunteer blood donors were investigated. TT virus (TTV) DNA detection and genotyping were performed using a semi-nested polymerase chain reaction with specific primers. The prevalence of TTV DNA in patients on HD (66%) was significantly (P<0.001) higher than in blood donors (24%) with genotype 1b predominance (89%) in both. Clinical background including mean age, sex, history of blood transfusion, and positive markers for either hepatitis B virus (HBV) or hepatitis C virus (HCV) did not differ between TTV DNA positive and negative HD patients. However, the mean duration of HD was significantly (P=0.032) shorter in the TTV positive patients (28+/-19 months) than in the negative ones (45+/-34 months). Mean alanine aminotransferase level in patients with HCV infection alone (41+/-24 IU/l) did not differ from that in patients with both co-infection (33+/-28 IU/l), but was significantly higher than that in patients with TTV infection alone (26+/-10 IU/l). Occurrence of chronic hepatic changes in patients with TTV infection alone (7%) was significantly less common than those with HCV infection alone (100%, P<0.001) or those with both co-infection (100%, P<0.001). Serum level of HCV core protein was similar between patients with HCV infection alone and those with co-infection with TTV. In conclusion, the prevalence of TTV infection is high in Egyptian patients on regular HD, especially with shorter duration on HD. No clinical significance of TTV virus could be elicited in HD Egyptian patients; neither it showed any clinical impact as a co-infection with HCV.

Journal Article↗

PubMed2002

An adult case of skeletal open bite with a severely narrowed maxillary dental arch.

Surgically assisted rapid maxillary expansion is proposed as an efficient approach for adult patients with transverse maxillary deficiency. This article reports the treatment of an 18-year, seven-month old male patient with an anterior open bite and a severely narrowed upper dental arch. A posterior crossbite was present on both sides. For the correction of the posterior crossbite, a lateral maxillary expansion of more than 8 mm was required. A surgically assisted rapid maxillary expansion with Le Fort I corticotomy and mandibular setback with a sagittal splitting ramus osteotomy were determined as the treatment plan. The total treatment time was 24 months including five months of post-surgical observation. After the treatment, an acceptable occlusion was achieved with a Class I molar relationship. The amount of actual maxillary expansion was 6.3 mm at the canines and 9.7 mm at the first molars. The relapse of the expansion was 0.9 mm and 0.1 mm at the corresponding regions two years after the surgically assisted maxillary expansion. It is emphasized that surgically assisted rapid maxillary expansion is a secure and efficient approach for achieving a desirable lateral maxillary expansion with stability in adult patients demonstrating transverse maxillary deficiency. Furthermore, it is suggested that longterm observation of the maxillary arch width after retention is of a great importance for the maintenance of the acceptable treatment outcome.

Adolescent↗