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Biomedical subjects

J Tamura

Publications and source records attributed to J Tamura.

At least 37 records · Page 2Linked to original sources
PubMed2001

In vivo three-dimensional knee kinematics using a biplanar image-matching technique.

A biplanar image-matching technique was developed and applied to a study of normal knee kinematics in vivo under weightbearing conditions. Three-dimensional knee models of six volunteers were constructed using computed tomography. Projection images of the models were fitted onto anteroposterior and lateral radiographs of the knees at hyperextension and every 15 degrees from 0 degrees to 120 degrees flexion. Knee motion was reconstructed on the computer. The femur showed a medial pivoting motion relative to the tibia during knee flexion, and the average range of external rotation associated with flexion was 29.1 degrees . The center of the medial femoral condyle translated 3.8 mm anteriorly, whereas the center of the lateral femoral condyle translated 17.8 mm posteriorly. This rotational motion, with a medially offset center, could be interpreted as a screw home motion of the knee around the tibial knee axis and a posterior femoral rollback in the sagittal plane. However, the motion of the contact point differed from that of the center of the femoral condyle when the knee flexion angle was less than 30 degrees. Within this range, medial and lateral contact points translated posteriorly, and a posterior femoral rollback occurred. This biplanar image-matching technique is useful for investigating knee kinematics in vivo.

Adult↗
PubMed2001

Evaluation of signal-averaged electrocardiography for clinical diagnosis in arrhythmogenic right ventricular dysplasia.

Arrhythmogenic right ventricular dysplasia (ARVD) is a heart muscle disorder of unknown etiology that is characterized pathologically by fibrofatty replacement of the right ventricular myocardium. We investigated the relationship between the electrocardiogram (ECG) appearances and signal-averaged ECG (SAECG) in 7 cases with ARVD, and evaluated the usefulness of SAECG as a screening test to detect patients with ARVD. Compared with the conventional 12-lead ECG, the SAECG detects abnormalities at a higher rate in ARVD patients (57% versus 86%). SAECG was more sensitive as a screening test to detect patients with ARVD than 12-lead ECG.

Adolescent↗
PubMed2001

Long-term follow-up study of bioactive bone cement for repairing a segmental defect in a canine femur.

We report on a 7-year long-term follow-up study of a bioactive bone cement (BA cement) that was used to repair a segmental defect in a canine femur. Bilateral femoral segmental defects were repaired with metallic implants that were fixed to the femur using two kinds of bone cement. The BA cement used in this study consists of an apatite- and wollastonite-containing glass ceramic (AW-GC) with a bis-phenol-alpha-glycidyl methacrylate (bis-GMA)-based resin. The bone-cement interface was examined histologically. Previous short-term studies have shown that using BA cement for segmental replacement of the canine femur produced excellent biomechanical and histological results. The BA cement maintained the fixation of a metallic implant to the femur very well. In contrast, the PMMA cement did not maintain alignment under long-term weight-bearing conditions. The results of histological examinations showed direct bonding between the BA cement and bone, while an intervening soft tissue layer was observed at the bone-cement interface with the PMMA cement. The BA cement bonded to the bone through a Ca-P-rich reactive layer, which was twice as thick after 7 years than it was at 26 weeks. No adverse effects of BA cement were observed during the 7-year observation period.

Animals↗
PubMed2001

Reduction of viral myocarditis in mice lacking perforin.

Cellular immunity plays an important role and contributes to morbidity and mortality in the development of cardiomyopathy secondary to acute myocarditis. Lymphocytotoxicity has been proposed as due to infiltrated cytotoxic T lymphocytes (CTLs). Perforin is thought to be a major factor responsible for the cytolytic properties of the CTLs. To investigate whether mice lacking perforin have enhanced severity of viral myocarditis and acceleration of myocardial apoptosis, perforin knockout (KO) mice were infected with encephalomyocarditis virus. The average cardiac viral titer in perforin KO mice was not significantly different from that in the wild type mice. The heart weight/body weight ratio in perforin KO mice on days 4 and 12 were the same in the wild type mice (n=4 of each). Hearts in perforin KO mice were smaller than that in perforin + mice and grades of myocardial necrosis and lymphocyte infiltration were significantly reduced than in perforin + mice on day 12 after viral inoculation. In the perforin KO mice, the number of apoptotic cells was significantly higher than in wild type on day 4. Perforin blockade induced the early induction of myocardial apoptosis and suppressed the late onset of myocardial injury by cellular autoimmunity. Blockade of perforin gene expression at an early stage may limit viral myocarditis for therapeutic intervention.

Animals↗
PubMed2000

Detection of tumor cells in blood using CD45 magnetic cell separation followed by nested mutant allele-specific amplification of p53 and K-ras genes in patients with colorectal cancer.

A new method for detecting circulating tumor cells that is based on magnetic-activated cell separation (MACS) and nested mutant allele-specific amplification (nested MASA) was evaluated in patients with colorectal cancer using the p53 and K-ras genes as genetic markers. By negative selection with anti-CD45 monoclonal antibody-conjugated supermagnetic microbeads, the proportion of tumor cells was enriched 9-fold. By the combination of MACS and nested MASA, 10 tumor cells in 10(7) normal peripheral blood mononuclear cells could be detected without false-positives. Using this method, we examined blood taken from the tumor drainage veins of 23 patients with colorectal cancer. Eighty-seven percent (20/23) of primary tumor tissues showed p53 and/or K-ras gene mutations. Forty-five percent (9/20) of patients with p53 and/or K-ras mutations in the primary tumor showed the same mutated genes in the blood samples. There was a significant association between the presence of p53 and K-ras gene mutation in the blood and tumor size, depth of invasion, and venous invasion. Blood gene mutation was detected in 80% (4/5) of samples from patients with synchronous liver metastases. Sixty percent (3/5) of patients with mutant genes in the blood developed asynchronous liver metastases after surgery. The overall survival of patients with p53 and/or K-ras gene mutation-positive findings in blood was significantly shorter than that of patients testing negative on Kaplan-Meier analysis. Our results suggest that the method may be useful for reliable detection of tumor cells circulating in the blood and may help to identify patients at high risk for relapse.

Adenocarcinoma↗
PubMed2000

Multiple myeloma presenting high fever and high serum levels of lactic dehydrogenase, CRP, and interleukin-6.

Two myeloma patients presented high fever with no signs or data indicating infection at diagnosis or relapse. Both patients had plasmablastic myeloma, and serum levels of lactic dehydrogenase (LDH) and CRP were extremely high. Plasmablastic morphology, high LDH, and CRP were recognized as poor prognostic factors, indicating a fulminant phase of multiple myeloma. Interleukin-6 (IL-6) was only high in measured cytokines. We proposed that IL-6 caused high fever and induced the fulminant phase in these 2 cases.

C-Reactive Protein↗
PubMed2000

Two cases of chronic graft-versus-host disease with elevated levels of soluble Fas ligand in serum.

It has recently been shown that the Fas-Fas ligand (FasL) system may be one of the pathogeneses for acute graft-versus-host disease (GVHD), and it has been reported that serum soluble Fas ligand (sFasL) increases with the presence of acute GVHD. However, there is no report on a correlation between the Fas-FasL system and chronic GVHD. We present two cases of chronic GVHD with elevated levels of serum sFasL. Its level in each case was high at the onset of chronic GVHD, but it decreased with steroid therapy. Liver dysfunction also improved as the level of serum sFasL decreased. It appears in these cases that the Fas-FasL system was related to the pathogenesis of liver damage.

Adolescent↗
PubMed2000

Possible existence of platelet activation before the onset of cerebral infarction.

To study the existence of platelet activation before the onset of cerebral infarction, the ultrastructural features of platelets (7-day survival) and coagulation-fibrinolytic markers (70-100-min life span) were measured 2-12 h (acute phase), 7 days (subacute phase) and 6 months (chronic phase) after onset in 18 patients with cerebral infarction. Seven patients with atherosclerosis but without cerebral infarction and eight healthy subjects were studied as controls. Ultrastructural study included folds, pseudopods, vacuoles and centralization in addition to immunochemical staining such as platelet peroxidase and fibrinogen. Furthermore, beta-thromboglobulin, platelet factor-4, thrombin antithrombin complex and alpha(2)-plasmin inhibitor plasmin complex were examined as coagulation-fibrinolytic markers. Ultrastructural study of circulating platelets demonstrated no difference between acute and chronic phases and little difference between cerebral infarction and atherosclerosis, although plasma coagulation-fibrinolytic markers showed an increase in cerebral infarction at the acute phase but no difference among the chronic phase of cerebral infarction, atherosclerosis and normal healthy subjects. It is considered that shape change in circulating platelets was caused by pre-existed atherosclerosis rather than the thrombotic event itself though coagulation-fibrinolytic markers were derived from the thrombotic event.

Aged↗
PubMed2000

Enhanced expression of vsmNOS mRNA in glomeruli from rats with unilateral ureteral obstruction.

BACKGROUND: The vasodilatory/cytotoxic gas, nitric oxide (NO), is associated with an alteration in glomerular hemodynamics seen after the induction of ureteral ligation. As yet the type of nitric oxide synthase (NOS) protein involved in the mechanism has not been clearly established in the unilateral ureteral obstruction (UUO) model. METHODS: Using reverse transcription (RT)-polymerase chain reaction (PCR), the expression and localization of vascular smooth muscle-derived nitric oxide synthase (vsmNOS) mRNA were examined in glomeruli from sham-operated control (SOC) rats and rats with UUO of three hours duration. Moreover, the effect of endogenous angiotensin II on the expression of vsmNOS mRNA in glomeruli was explored using SOC rats and rats with UUO that were pretreated or not with enalapril, an angiotensin-converting enzyme inhibitor. RESULTS: The expression of vsmNOS mRNA was significantly greater in glomeruli of rats with UUO than in those of SOC rats. In rats with UUO, the expression of vsmNOS mRNA was substantially increased in glomeruli of the obstructed kidney (OK) compared to the contralateral, nonobstructed kidney (CLK). Suppression of angiotensin II production in vivo with enalapril restored the expression of vsmNOS mRNA in glomeruli of the CLK and OK from rats with UUO to levels comparable to that seen in glomeruli from SOC rats. In addition, the in situ RT-PCR analysis, a novel method for mRNA identification in cells and tissue, revealed that vsmNOS mRNA was expressed in the cytoplasm of glomerular mesangial and epithelial cells in SOC rats and rats with UUO. CONCLUSIONS: An increase in vsmNOS mRNA expression in glomeruli of the CLK and OK from rats with UUO may be mediated by increased action of endogenous angiotensin II that occurs after the onset of ureteral obstruction. Enhanced expression of vsmNOS mRNA in glomeruli of the OK compared to the CLK may be due to differences in levels of angiotensin II acting on the two kidneys in vivo. Additionally, the expression of vsmNOS mRNA in glomeruli originates in mesangial and epithelial cells in SOC rats and rats with UUO.

Animals↗
PubMed2000

Factor VII R110C: a novel missense mutation (Arg110Cys) in the second epidermal growth factor-like domain causing factor VII deficiency in members of a Japanese family.

This report describes the findings of a genetic analysis of the factor VII (FVII) gene in a Japanese, male patient with FVII deficiency. The proband showed FVII activity level of 25% and FVII antigen level of 28% of the normal value, but he had no severe bleeding episodes. We identified the mutation by direct sequencing of polymerase chain reaction products representing all exons except 1b and their flanking intronic regions of his FVII gene. We detected a single point mutation, a C-->T substitution at nucleotide position 7863 in exon 5, which results in an amino acid replacement of Arg (CGC) to Cys (TGC) at codon 110 in the second epidermal growth factor-like domain. Homozygosity was confirmed in the propositus by loss of a site for the restriction endonuclease Eco47III. Furthermore, his parents, who had moderately reduced levels of factor VII activity and antigen, carried this mutation site as a heterozygote. Although the Arg11O residue is located distal to the tissue factor (TF) in the soluble TF-FVIIa crystal structure, we infer that the replacement of the positively charged and larger Arg residue with a neutral Cys residue may be likely to impair proper folding, resulting in destabilization of the protein structure.

Adult↗
PubMed2000

Circulating interleukin-6 and interleukin-6 receptors in patients with acute and recent myocardial infarction.

Interleukin-6 (IL-6), a proinflammatory cytokine, plays a key role in the pathogenesis of coronary artery disease (CAD). We investigated circulating IL-6 and its receptors in patients with CAD. We evaluated 39 Japanese patients with CAD (30 males and 9 females aged 36-79 years), measuring their plasma levels of IL-6 and IL-6 receptors alpha and beta (IL-6R alpha, IL-6R beta). Circulating levels of IL-6, IL-6R alpha and IL-6R beta were measured by an enzyme-linked immunosorbent assay. Blood was sampled immediately after admission and again after 1, 2, 3, 6 and 9 h, then every 12 h for 5 days. Atrial natriuretic peptide (ANP) and B-type natriuretic peptide (BNP) were measured on day 3 after symptom onset. Plasma levels of IL-6 and IL-6Rs were significantly increased in 28 patients with acute myocardial infarction (AMI) compared with 15 normal controls. However, neither IL-6 nor IL-6Rs showed an increase in 6 patients with angina pectoris. We observed two peaks for circulating IL-6 in AMI, the first of which showed a significant correlation with ANP as well as BNP. These results may help to explain why the amount of IL-6 produced is closely related to the severity of myocardial dysfunction in patients with CAD.

Adult↗
PubMed2000

Prolongation of QT interval and ventricular septal hypertrophy.

Long QT syndrome (LQTS) is a prime example of interplay between molecular biology, cellular physiology, and organ physiology. Both the congenital and acquired forms of LQTS are due to intrinsic and/or acquired abnormalities of the ionic currents responsible for cardiac repolarization. We analyzed the QTc interval, QRS axes and interventricular septal thickness (IVST) in 41 patients who had a prolonged QT interval on routine electrocardiography (ECG) (5 females and 36 males, mean age 65+/-13 years). The QRS axis of patients in the LQTS group (27+/-49 degrees) was significantly lower (p < 0.05) than in the control group (46+/-26 degrees). However, the IVST in the LQTS group (10+/-2 mm) was significantly thicker than in the control group (9+/-1 mm) (p < 0.05), while the WTd was not significantly different. The QTc interval in patients with ventricular septal hypertrophy (IVST > or = 12 min, 478.8+/-7.9 msec) was significantly longer (p < 0.05) than in the normal group (IVST < 12 mm, 472.1+/-17.5 msec). In conclusion, the results of this preliminary study suggest that prolongation of the QT interval on ECG should prompt screening for electrocardiographic evidence of ventricular hypertrophy in patients with this disease.

Adult↗
PubMed2000

[Effect of etoposide added to individualized induction therapy of adult acute myeloid leukemia--the JALSG-AML-92 Study. Japan Adult Leukemia Study Group].

A multicenter prospective randomized study was undertaken to assess the efficacy of etoposide added to the standard remission induction therapy for acute myeloid leukemia (AML). Consecutively registered newly diagnosed adult AML patients were randomized to receive either daunorubicin (40 mg/m2/day x 4 or more), behenoyl cytarabine (200 mg/m2/day x 10 or more) and 6-mercaptopurine (70 mg/m2/day x 10 or more) (BH-AC-DM), or the same three drugs plus etoposide (100 mg/m2/day x 5) (BH-AC-EDM) for response-oriented individualized induction therapy. The patients achieving complete remission (CR) received the same 3 courses of consolidation therapy followed by 6 courses of maintenance/intensification therapy. M3 was excluded and M0 was included. Of 667 patients registered, 655 were evaluable. The median age was 49 years (range, 15 to 85). CR rates were 77% in the BH-AC-DM group and 75% in the BH-AC-EDM group. In M4 patients, CR rates were 86% and 69% (p = 0.009), and, in M5, 80% and 77% (p = 0.810) in the BH-AC-DM and BH-AC-EDM groups, respectively. The predicted 6-year overall survival rates were 30% and 38% for BH-AC-DM and BH-AC-EDM groups, and the disease-free survival (DFS) rates of CR patients were 25% and 35% (p = 0.925), respectively. In conclusion, the present study failed to show any advantage of the addition of etoposide to the standard individualized induction therapy in adult AML, even among M4 and M5. These above data have already been published in the Int J Hematol (70: 87-104, 1999).

Adolescent↗
PubMed2000

[Treatment of acute promyelocytic leukemia with all-trans retinoic acid and chemotherapy--multicenter trial of the Japan Adult Leukemia Study Group (JALSG)].

We report herein the clinical results of a multicenter trial of the Japan Adult Leukemia Study Group for cases of newly diagnosed acute promyelocytic leukemia (APL) treated with all-trans retinoic acid and chemotherapy (JALSG AML-92 study). Of 196 evaluable patients, 173 (88%) achieved complete remission (CR). Multivariate analysis showed that no or minor purpura at diagnosis and age less than 30 years were favorable factors for achievement of CR. There was a significant difference in the 4-year event-free survival between the AML-92 study (54%) and both the AML-87 (32%) and AML-89 (32%) studies which consisted of intensive chemotherapy. Since prognosis in patients with APL largely depends on chemotherapy, it is important to consider more effective chemotherapy during induction and consolidation therapy.

Aclarubicin↗
PubMed2000

Markers of undiagnosed incidental cancer in comparison with clinical prostatic cancer.

We propose that carcinoembryonic antigen (CEA) may be a tumor marker for prostatic cancer in addition to prostate specific antigen (PSA), gamma-seminoprotein and prostate acid phosphatase (PAP). The tests were done on 15 sera and autopsy specimens of prostatic cancer. Eight of them were clinical cancers and the remaining seven were incidental ones. We measured serum PAP, PSA, CEA and CA 19-9 and immunohistochemically evaluated these specimens. In clinical cancers, serum PAP, PSA, CEA and CA 19-9 were 1272.9 +/- 3094.4, 146.7 +/- 233.6, 36.3 +/- 36.0 and 80.4 +/- 92.0. Immunohistochemically, all were positive for PAP, PSA, CEA and CA 19-9. In incidental cancers, serum PAP, PSA, CEA and CA 19-9 were 2.4 +/- 1.5, 7.9 +/- 16.9, 128.1 +/- 182.7 and 201.8 +/- 416.1. We conclude that the patients with higher levels of plasma PAP or PSA should go through CEA and CA 19-9 measurement in order to diagnose clinical prostatic cancer.

Acid Phosphatase↗
PubMed2000

Positive correlation between circulating leptin levels and lipid lipoproteins in postmenopausal women administered hormone replacement therapy.

Beneficial effects of hormone replacement therapy are reported on plasma concentrations of lipids and lipoproteins. Plasma leptin levels are reported to reflect lipid metabolism. We treated 40 healthy postmenopausal women with continuous combined HRT (0.625 mg conjugated equine estrogen and 2.5 mg medroxyprogesterone acetate orally) daily for 6 months and then investigated total cholesterol, triglyceride, high-density lipoprotein (HDL) cholesterol, and low-density lipoprotein (LDL) cholesterol, which are considered to be factors inducing cardiovascular disease (CVD). We measured the plasma levels of lipids and leptin, which are considered to be altered with HRT. Plasma leptin and lipid levels were measured at baseline and after 3 and 6 months of HRT. The plasma levels of leptin in PMW were not significantly reduced by HRT. Although the plasma levels of total cholesterol and LDL-cholesterol did not change by HRT, the administration of HRT significantly increased plasma levels of triglycerides and HDL-cholesterol in PMW. The correlation between leptin and total cholesterol or triglycerides was positive after HRT while these relations were not correlated at baseline. The correlation between lipid levels and leptin may explain the new role of leptin in plasma lipid levels in HRT.

Aged↗