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Biomedical subjects

Kazuo Tanaka

Publications and source records attributed to Kazuo Tanaka.

52 records · Page 3Linked to original sources
PubMed2003

Clear distinction of pyrimidine bases on the complementary strand by fluorescence change of novel fluorescent nucleosides.

New fluorescent nucleosides, methoxybenzodeazaadenine ((MD)A) and methoxybenzodeazainosine ((MD)I) which can sharply distinguish between C and T bases, respectably. The hybridization of an ODN probe containing (MD)A and (MD)I with a target DNA facilitates the judgment with the fluorescence spectra of the type of pyrimidine bases located at a specific site on the target DNA. The (MD)A- and (MD)I containing ODN are very effective probes for pyrimidine SNP typing.

Adenine↗
PubMed2003

Enzymatic ligation and extension of DNA wire.

The ODNs containing (MD)A, which effectively mediate hole transport, were enzymatically ligated, and photo-induced hole transport reaction proceeded efficiently through a ligated long duplex. The ligated duplex showed high hole transport efficiency.

Autoradiography↗
PubMed2003

A real-time quantitative polymerase chain reaction method for hepatitis B virus in patients with chronic hepatitis B treated with lamivudine.

OBJECTIVES: During treatment of chronic hepatitis B with lamivudine, changes in the level of hepatitis B virus (HBV) DNA were investigated using a real-time polymerase chain reaction (PCR) method with a detection limit of 1.7 log copies/ml (50 copies/ml) to clarify its clinical significance, particularly the association between HBV DNA levels and the emergence of tyrosine-methionine-aspartate-aspartate (YMDD) mutants. METHODS: Twenty-four patients who had received lamivudine therapy for >1 yr were studied. HBV DNA levels were determined using transcription-mediated amplification for sera with >3.7 log genome equivalents/ml, the Roche Monitor kit for sera with >/=2.6 log copies/ml, and real-time PCR for sera with < 2.6 log copies/ml (the detection limit was 1.7 log copies/ml). Patients were classified into three groups according to the minimal HBV DNA level attained during lamivudine therapy: the <1.7 log copies/ml group (eight patients), the 1.7-2.5 log copies/ml group (five patients), and the >/=2.6 log copies/ml group (11 patients). RESULTS: Pretreatment HBV DNA levels were significantly lower in the <1.7 copies/ml group than in the other two groups (p < 0.05). Neither the emergence of YMDD mutants nor a virological breakthrough of serum HBV DNA was observed in any of the eight patients in the <1.7 copies/ml group. In contrast, in the 1.7-2.5 copies/ml and >/=2.6 copies/ml groups, virological breakthroughs resulting from the emergence of YMDD mutants were observed in two of five patients and in all 11 patients, respectively (p < 0.001). Virological breakthroughs were observed at a mean of 49.6 +/- 18.4 wk in 11 the patients in the >/=2.6 copies/ml group and at wk 107 and 115 in two patients in the 1.7-2.5 copies/ml group. CONCLUSIONS: The real-time PCR method is useful for predicting the emergence of YMDD mutants and the estimated time of their emergence.

Adult↗
PubMed2003

Subclones of drug-resistant hepatitis B virus mutants and the outcome of breakthrough hepatitis in patients treated with lamivudine.

Breakthroughs during lamivudine therapy were assessed according to hepatitis flares and mutational polymorphism of hepatitis B virus (HBV) infecting patients. Of 42 patients with chronic hepatitis B and positive for hepatitis B e antigen in serum, 13 (30%) harbored HBV mutants with lamivudine resistance after a mean duration of 29 months on lamivudine. The virological breakthrough occurred 14.5 months after the start of lamivudine treatment, and all the patients with it developed breakthrough hepatitis 3 months later. The clinical course of breakthrough hepatitis was self-limited except in one patient who had already developed cirrhosis at the baseline. One year after breakthrough hepatitis, serum ALT, albumin, prothrombin time and platelet counts were maintained well on conventional treatments without resorting to interferon. Major HBV mutants during breakthrough hepatitis were those with M552I in the YMDD motif of viral DNA polymerase/reverse transcriptase in 7 patients (54%), M552I/L528M in 4 patients (31%) and M552V/L528M in 2 patients (15%). There were no patients in whom mutations at nucleotide 529 occurred including the 2 who later developed hepatocellular carcinoma. There was no clear relationship between distinct mutational patterns and clinical courses. Further studies are needed for making out the effects of lamivudine-resistant mutants on clinical outcomes, taking into considerations genotypes of HBV.

Antiviral Agents↗
PubMed2003

Accurate analysis of power coupling between two arbitrarily ended dielectric slab waveguides by the boundary-element method.

The boundary integral equations that are called guided-mode extracted integral equations are applied to the investigation of the power-coupling-properties between two arbitrarily ended dielectric slab waveguides. The integral equations derived in this paper can be solved by the conventional boundary-element method. The reflection and coupling coefficients of the guided wave, as well as the scattering power, are calculated numerically for the case of incident TE guided-mode waves. The results presented are checked by the energy conservation law and the reciprocity theorem. Numerical results are presented for several geometries of coupling, including systems with three-layered symmetrical and asymmetrical slab waveguides.

Journal Article↗
PubMed2003

A pilot study of eicosapentaenoic acid therapy for ribavirin-related anemia in patients with chronic hepatitis C.

One of the major side effects of ribavirin/interferon alpha combination therapy for chronic hepatitis C is hemolytic anemia. One of the causes of hemolytic anemia is considered to be decreasing deformability of erythrocytes resulting from the accumulation of phosphorylated ribavirin in erythrocytes. The administration of eicosapentaenoic acid (EPA), which has a wide variety of pharmacological actions, increases the deformability of erythrocytes. We conducted an uncontrolled pilot study of EPA therapy for patients with ribavirin-related anemia. Six patients with chronic hepatitis C, who had developed anemia while receiving combination therapy, were treated with an oral ethyl ester of EPA (1800 mg/day) for two months. The hemoglobin level of all six patients increased following EPA therapy. The mean hemoglobin level significantly increased from 10.8 g/dl to 11.4 g/dl one month after therapy was initiated (P<0.05), and this level was obtained again one month later (11.5 g/dl). None of the patients developed an adverse reaction. These findings suggest that EPA has a beneficial effect in patients with ribavirin-related anemia. Further study is required to confirm our results.

Adult↗
PubMed2003

Predictive factors for remission and death in 73 patients with autoimmune hepatitis in Japan.

The prognosis of patients with autoimmune hepatitis (AIH) has not been clearly defined. The aim of this study was to define the prognostic factors of AIH in a population with long-term follow-up in Japan. Seventy-three patients who were diagnosed as having type 1 AIH between January, 1972 - August, 1999 were enrolled in this study. Initial treatment included prednisolone (PSL) (n=62), other drug regimens (n=7), and none (n=4). We examined the relation between several factors obtained at diagnosis in relation to disease activity found at the final observation point (January, 2000 - April, 2000). Multivariate logistic regression and Cox regression were used for statistical analysis. During the observation period, 8 patients died of the following: hepatic failure (n=4), hepatocellular carcinoma (n=1), severe infection (n=1), and unknown causes (n=2). At the end point, the number of patients in complete remission was 13, those with a normal alanine aminotransferase (ALT) level requiring some treatment was 35, and those with an abnormal ALT level despite medication was 17. Factors related to remission were total bilirubin (TB) (Odds ratio, 0.87), and immunoglobulin G (IgG) (Odds ratio, 1.00). Factors related to death were the aspartate aminotransaminase (AST)/ALT ratio (Odds ratio, 11.67) and response to initial PSL regimen (Odds ratio, 0.03). The results of this study show an importance of achieving a good PSL response at onset, and that initial TB, the AST/ALT ratio, and IgG levels are useful for therapeutic strategy.

Adult↗
PubMed2003

Immunosuppressive agents and cytomegalovirus infection.

Cytomegalovirus (CMV) infection is the major infectious complication observed after organ transplantation. As rejection episodes always occur in allograft-transplanted recipients, various kinds of immunosuppressive agents are used to control such rejection episodes. Among the commonly used immunosuppressive agents, anti-pan-T cell polyclonal and monoclonal antibody are known to increase the risk of viral infections. New immunological techniques have recently been developed to measure CMV-specific CD4 and CD8 cells by flow cytometry. Using the techniques, high frequencies of specific CD4 and CD8 T cells have been shown to be required to survey the CMV (re)activation in the persistent/latent phase of CMV infection. An excessive T cell depletion by OKT3 would deplete such surveying T cells, thus resulting in the occurrence of CMV-associated diseases.

Animals↗
PubMed2002

2-Amino-7-deazaadenine forms stable base pairs with cytosine and thymine.

2-Amino-7-deazaadenine ((AD)A) was incorporated into oligodeoxynucleotides (ODN) and their base-pairing properties with natural nucleobases were investigated. In melting temperature (T(m)) experiments, the duplex containing an (AD)A/C base pair showed a high stability comparable to that containing (AD)A/T base pair. Destabilization of the duplex usually observed for existing degenerate bases was not observed. However, the incorporation efficiency of dCTP was only 1.8% for TTP in single-nucleotide insertion reactions using polymerase.

Adenine↗
PubMed2002

Specificity of polymerase chain reaction-based clonality analysis of immunoglobulin heavy chain gene rearrangement for the detection of bone marrow infiltrate in B-cell lymphoma-associated haemophagocytic syndrome.

As a wide range of disorders underlie haemophagocytic syndrome, a rapid distinction between benign polyclonal and malignant monoclonal lymphoid proliferations is critical. We investigated whether polymerase chain reaction (PCR) amplification of immunoglobulin heavy chain gene rearrangement could efficiently detect clonal B-cell populations in non-diagnostic marrow for B-cell lymphoma-associated haemophagocytic syndrome (B-LAHS). On amplifying two DNA samples per biopsy, no reproducible monoclonal PCR result was found in reactive haemophagocytic marrows. In contrast, four out of nine assessable B-LAHS patients with histomorphologically and immunohistochemically lymphoma-free bone marrow showed a reproducible monoclonal immunoglobulin heavy chain gene rearrangement. At the molecular level, two B-LAHS patients had lymphoma-free marrow as demonstrated by patient-specific PCR, suggesting that haemophagocytic marrow is not always associated with lymphoma involvement. PCR-based demonstration of clonal B-cell populations in marrow would add an extra dimension to B-LAHS diagnosis.

Aged↗
PubMed2002

Roles of tumor necrosis factor-alpha-receptor type 1 and Fas in the Helicobacter pylori-induced apoptosis of gastric epithelial cells.

OBJECTIVES: Helicobacter pylori (HP) infection has been reported to accelerate the apoptosis of gastric epithelial cells. This bacteria has also been known to enhance the expression levels of molecules such as Fas antigen and a receptor for tumor necrosis factor-alpha-receptor type 1 (TNF-R1). However, whether Fas and/or TNF-R1 is actually involved in HP-mediated apoptosis has yet to be evaluated. The purpose of this study was therefore to examine the roles of Fas and TNF-R1 in HP-mediated apoptosis. METHODS: Biopsy samples were collected from 10 HP-negative healthy volunteers and from 39 HP-positive ulcer patients. Gastric epithelial cells were obtained from the samples. The cells were then stained with anti-Fas, anti-TNF-R1 and Annexin V, which detected apoptotic cells. The findings were analyzed by three-color flow cytometry. RESULTS: The percentages of apoptotic cells were significantly higher in HP-positive patients than in the controls. In HP-negative controls, almost all of the apoptotic cells lacked both Fas and TNF-R1. On the other hand, in HP-positive patients, HP upregulated the expression levels of Fas and TNF-R1 and, consequently, enhanced the apoptosis mediated by receptors such as Fas and TNF-R1. However, even in HP-positive patients, apoptosis was also observed in the cells that lacked both Fas and TNF-R1. CONCLUSIONS: Fas and TNF-R1 expressed on gastric epithelial cells from HP-infected patients were responsible for the accelerated apoptosis of the cells.

Adolescent↗
PubMed2002

Combination assay of urinary free L-fucose and trypsin inhibitor may be useful indicators of disease activity in patients with hematologic malignancies.

L-Fucose is a monosaccharide located at the non-reducing ends of sugar chains of glycoconjugates. Urinary L-fucose (U-FC) is excreted as free L-fucose, and clinically useful as a tumor marker of digestive organ cancers. We evaluated the clinical usefulness of U-FC levels in patients with various hematologic malignancies because U-FC for hematologic malignancies has only rarely been described. The mean U-FC levels in the acute nonlymphocytic leukemia (ANLL), myelodysplastic syndromes (MDS) and myeloproliferative disorders (MPD) groups were significantly higher than in the control group (P < 0.05). Recently, we reported that urinary trypsin inhibitor (UTI) levels in patients with ANLL, MDS, non-Hodgkin's lymphoma and multiple myeloma were significantly elevated, compared with those in healthy adult volunteers. Noninvasive combination assays of UTI and U-FC may have a higher accuracy in diagnosis of ANLL and MDS than those of UTI or U-FC alone. UTI and U-FC combination assays, noninvasive for patients, could be expanded as useful indicators in hematologic malignancies.

Biomarkers↗
PubMed2002

Numerical simulation of an arbitrarily ended asymmetrical slab waveguide by guided-mode extracted integral equations.

The scattering phenomenon from an arbitrary-shaped end of a asymmetrical slab waveguide for the cases of TE and TM guided modes is simulated by means of boundary integral equations that are called guided-mode extracted integral equations. The integral equations that we derive can be solved by the conventional boundary-element method. Numerical results are presented for problems of three-layer asymmetrical waveguides with tilted ends. The reflection coefficient, reflected and scattered powers, and radiation patterns are calculated numerically for the cases of incident TE and TM guided modes.

Journal Article↗
PubMed2002

[Fentanyl administration during sevoflurane anesthesia suppresses spike waves from epileptic focus on electrocorticogram].

A 36-year-old man with intractable epileptic seizures underwent insertion of subdural electrodes on bilateral temporal lobes under air-oxygen-sevoflurane anesthesia. After the completion of the operation, we measured electrocorticogram at end-tidal sevoflurane concentration of 2.5%, 1.5%, and 1.5% with 0.1 mg intravenous fentanyl. When sevoflurane concentration was reduced to 1.5%, the incidence and voltage of the spike waves on electrocorticogram were reduced. When 0.1 mg fentanyl was intravenously administrated during 1.5% sevoflurane anesthesia, the frequency of the spike waves was further reduced. Caution should be taken when using sevoflurane-fentanyl anesthesia because this combination may interrupt identification of epileptic focus on intraoperative electrocorticogram.

Adjuvants, Anesthesia↗