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Biomedical subjects

Masaru Tanaka

Publications and source records attributed to Masaru Tanaka.

At least 55 records · Page 3Linked to original sources
PubMed2004

Design of novel biointerfaces (I). Blood compatibility of poly(2-methoxyethyl acrylate).

We have reported that poly(2-methoxyethyl acrylate) (PMEA) shows excellent blood compatibility with respect to the coagulation, complement, leukocyte and platelet systems in vitro and ex vivo when compared with other polymer surfaces. In this study, to clarify the reasons for this good compatibility, the structure of water in the hydrated PMEA were investigated and compared to water structure of poly(2-hydroxyethyl methacrylate) (PHEMA) and polyacrylate analogs as references. The hydrated water in PMEA could be classified into three types; free water, freezing-bound water, and non-freezing water. Cold crystallization of water in the heating process was clearly observed at -42 degrees C. This cold crystallization is interpreted as the phase transition from the amorphous ice to the crystal ice that belongs to the freezing-bound water in PMEA. On the other hand, the cold crystallization peak (freezing bound water; which prevents the biocomponents from contacting the polymer surface or non-freezing water on the polymer surface) was not observed for hydrated PHEMA and PMEA analogous polymers. We hypothesized that the freezing-bound water layer between free water and non-freezing water was an important factor for the excellent blood compatibility of PMEA.

Absorption↗
PubMed2004

Design of novel biointerfaces (II). Fabrication of self-organized porous polymer film with highly uniform pores.

Application of porous polymer materials to novel bio-interfaces for tissue engineering scaffold and artificial organs including blood filters, dialyzer, and oxygenator membranes have been in progress. The present study describes the fabrication and characterization of self-organized highly regular porous polymer films with uniform pore sizes are prepared by simple casting technique. Various fabrication parameters affecting the pore size such as polymer concentration, boiling point of solvent, cast volume and substrate are studied. The pore size can be controlled in the range from 1 to 50 microm by changing the evaporation rate of the polymer solutions. The porous film with uniform pore size is used for tissue engineering scaffold and cell separation membrane. To simulate the leukocyte eliminating from human blood, the porous film was attached to a module. The films with 5-9 microm pores provided the complete selectivity of separation for the leukocyte from the whole blood. The leukocyte elimination ratio depends on pore structures (size and depth) as well as recovery of platelet and erythrocyte.

Acrylamides↗
PubMed2003

Stereoselectivity of superacid-catalyzed Pictet-Spengler cyclization reactions.

[reaction: see text] High stereoselectivities were found in a wide range of superacid-catalyzed Pictet-Spengler cyclization reactions. Particularly in the cases of 2-alkyl-N-benzylidene-2-phenethylamines, an enhanced stereoselectivity was observed under the superacid conditions as compared with the corresponding weak acid (TFA)-catalyzed (monocationic) cyclization reaction of the N-benzylidene-2-(3',4'-dimethoxy)phenethylamines that bear electron-donating groups on the cyclizing aromatic ring. The computational study also supported the energetic favorability of the cyclization of the N,N-diprotonated imine and revealed a significantly early transition-state structure.

Journal Article↗
PubMed2003

Molecular cloning and characterization of CYP719, a methylenedioxy bridge-forming enzyme that belongs to a novel P450 family, from cultured Coptis japonica cells.

Two cytochrome P450 (P450) cDNAs involved in the biosynthesis of berberine, an antimicrobial benzylisoquinoline alkaloid, were isolated from cultured Coptis japonica cells and characterized. A sequence analysis showed that one C. japonica P450 (designated CYP719) belonged to a novel P450 family. Further, heterologous expression in yeast confirmed that it had the same activity as a methylenedioxy bridge-forming enzyme (canadine synthase), which catalyzes the conversion of (S)-tetrahydrocolumbamine ((S)-THC) to (S)-tetrahydroberberine ((S)-THB, (S)-canadine). The other P450 (designated CYP80B2) showed high homology to California poppy (S)-N-methylcoclaurine-3'-hydroxylase (CYP80B1), which converts (S)-N-methylcoclaurine to (S)-3'-hydroxy-N-methylcoclaurine. Recombinant CYP719 showed typical P450 properties as well as high substrate affinity and specificity for (S)-THC. (S)Scoulerine was not a substrate of CYP719, indicating that some other P450, e.g. (S)-cheilanthifoline synthase, is needed in (S)-stylopine biosynthesis. All of the berberine biosynthetic genes, including CYP719 and CYP80B2, were highly expressed in selected cultured C. japonica cells and moderately expressed in root, which suggests coordinated regulation of the expression of biosynthetic genes.

Alcohol Oxidoreductases↗
PubMed2003

Fine structure of soft and hard tissues involved in eye migration in metamorphosing Japanese flounder (Paralichthys olivaceus).

The body of a Japanese flounder (Paralichthys olivaceus) changes from a symmetrical to an asymmetrical form during metamorphosis. To obtain detailed information on the mechanisms of the migration of the right eye to the left side, soft and hard tissues in the head of larval flounders were examined using transmission electron microscopy (TEM). Retrorbital vesicles (Rvs) are pairs of sac-like structures under the eyes. It has been suggested that the asymmetrical development of Rvs, with the right (blind) one being bigger than the left, is the driving force behind eye migration. The present study revealed that the ultrastructure of the Rv sheath is quite similar to that of a lymphatic capillary. Thus, it is possible that the Rv is a part of the lymph system, and is probably related to the secondary vascular system in teleosts. If we assume that the Rv sheath has a high permeability to liquid, similar to lymphatic capillaries, it is not plausible that the active expansion of the Rv pushes the eyeball. On the other hand, the pseudomesial bar (Pb) is a bone that is unique to flounders and is present only on the right (blind) side. At the beginning of eye migration, an aggregation of fibroblast-like cells is observed in the dermis under the right eye, where the Pb will subsequently be formed. These cells have a well-developed rough endoplasmic reticulum (rER) and mitochondria, and are probably responsible for formation of the thick layers of collagen fibrils around them. Since it is unlikely that the active expansion of the Rv causes eye migration, the role played by the Pb and its rudiment becomes more significant in right eye migration in the Japanese flounder becomes more significant.

Animals↗
PubMed2003

Distribution of cholecystokinin-immunoreactive cells in the digestive tract of the larval teleost, ayu, Plecoglossus altivelis.

The ontogenetic development of cholecystokinin-immunoreactive (CCK-IR) cells was studied in larval ayu, Plecoglossus altivelis. This species has a straight digestive tract during the larval phase. CCK-IR cells were present in all the larvae from the day of hatching (0 days after hatching, DAH). An immunoreaction to anti-trypsinogen antibody was also detected in the pancreas at this stage. The distribution pattern of the CCK-IR cells was quantified by recording the location of CCK-IR cells at 1, 16, and 76 DAH. Although the number of CCK-IR cells increased during development, the distribution pattern of CCK-IR cells did not change until 76 DAH. The CCK-IR cells were scattered throughout the midgut, with the exception of the regions adjacent to the pyloric and rectal sphincters. No CCK-IR cells were detected in the foregut or the hindgut. This distribution pattern differs from species with rotated digestive tracts, whose CCK-IR cells are only found in the anterior part of the midgut. CCK-IR cells seem to be located in regions where the ingested food is retained and thus can easily receive chemical signals from the food and the digestive process in order to control the release of the hormone.

Animals↗
PubMed2003

Relevance of coplanar PCBs for TEQ emission of fluidized bed incineration and impact of emission control devices.

Five fluidized bed incinerators combusting municipal solid waste were assessed for the impact of coplanar PCBs on total TEQ emission. In 17 stack measurements, the coplanar PCBs contributed on average less than 3% to total TEQ with a maximum contribution of 7.5% to total TEQ in one measurement. Differences in the design of the flue gas cooling section did not show an effect on the impact of coplanar PCBs on total TEQ. The effect of emission control devices on the impact of coplanar PCBs on the total TEQ was studied in more detail at one incinerator. The relative contribution of PCBs to total TEQ increased along the flue gas line. This was caused by a slightly higher removal efficiency for TEQ relevant PCDDs/PCDFs compared to coplanar PCBs by the bag filters and a higher destruction efficiency for PCDDs/PCDFs compared to PCBs by the SCR catalyst. Additionally, the removal efficiencies of the emission control devices (bag filters and catalyst) for other chlorinated aromatic compounds which have been proposed as TEQ indicator compounds (polychlorinated benzenes and polychlorinated phenols) were compared with those for PCDDs/PCDFs and coplanar PCBs. Removal efficiencies for polychlorinated benzenes or polychlorinated phenols considerably differed from those of PCDD/PCDF and coplanar PCBs. Implications for TEQ assessments using indicator compounds as proposed in the literature are discussed.

Air Pollution↗
PubMed2003

Resolving public conflict in site selection process-a risk communication approach.

In Japan, conflicts regarding the siting of waste disposal facilities occur frequently. In particular, siting of incinerators and landfills has become increasingly difficult because the public is highly concerned about the dioxin issues. Inefficient siting of waste disposal facilities causes several social problems, such as the shortage of waste treatment and disposal facilities, the rising of waste management costs and an increase in the consumption of resources. While dealing with a similar situation, the Chemical Society of Japan adopted a risk communication technique successfully. Hence, the pragmatic use of a risk communication technique is proposed to avoid conflicts and for a smooth information exchange to seek cooperation in waste management. In order to achieve this, a study was conducted to resolve conflicts between residents and the municipality for the selection of site for a solid waste treatment and disposal facility. This study aims to discuss the subject of risk communication for the waste disposal system in Japan. This study is performed through personal interviews and a questionnaire covering opposing parties in the town. As a result of the survey, a risk communication approach for a waste treatment and disposal system is presented in the paper addressing issues such as building of social trust, pragmatic use of the communication process, installation of credible information sources, and environmental education and awareness.

Communication↗
PubMed2003

Dermoscopy of pigmented skin lesions: results of a consensus meeting via the Internet.

BACKGROUND: There is a need for better standardization of the dermoscopic terminology in assessing pigmented skin lesions. OBJECTIVE: The virtual Consensus Net Meeting on Dermoscopy was organized to investigate reproducibility and validity of the various features and diagnostic algorithms. METHODS: Dermoscopic images of 108 lesions were evaluated via the Internet by 40 experienced dermoscopists using a 2-step diagnostic procedure. The first-step algorithm distinguished melanocytic versus nonmelanocytic lesions. The second step in the diagnostic procedure used 4 algorithms (pattern analysis, ABCD rule, Menzies method, and 7-point checklist) to distinguish melanoma versus benign melanocytic lesions. kappa Values, log odds ratios, sensitivity, specificity, and positive likelihood ratios were estimated for all diagnostic algorithms and dermoscopic features. RESULTS: Interobserver agreement was fair to good for all diagnostic methods, but it was poor for the majority of dermoscopic criteria. Intraobserver agreement was good to excellent for all algorithms and features considered. Pattern analysis allowed the best diagnostic performance (positive likelihood ratio: 5.1), whereas alternative algorithms revealed comparable sensitivity but less specificity. Interobserver agreement on management decisions made by dermoscopy was fairly good (mean kappa value: 0.53). CONCLUSION: The virtual Consensus Net Meeting on Dermoscopy represents a valid tool for better standardization of the dermoscopic terminology and, moreover, opens up a new territory for diagnosing and managing pigmented skin lesions.

Algorithms↗
PubMed2003

Response of a neotenic goby, ice goby (Leucopsarion petersii), to thyroid hormone and thiourea treatments.

In order to clarify the mechanisms of neoteny in the ice goby (Leucopsarion petersii), we examined effects of thyroid hormone and thiourea (TU) treatments on their neotenic characteristics and the pituitary-thyroid axis. Adult ice goby were exposed to 3, 5, 3'-triiodothyronine (T3, 0.1 ppm), TU (inhibitor of thyroid hormone synthesis, 30 ppm), or the combination of the two for 2 weeks. Observations of whole body T3 levels, thyroid follicles and TSH immunoreactive cells in the pituitary suggests the presence of a functioning thyroidal system. However, all of the neotenic features did not disappear in T3-treated fish, suggesting the absence of T3 responsiveness in peripheral tissues. These results indicate the similarity between neoteny of the ice goby and obligatory-type neoteny of urodeles.

Animals↗
PubMed2003

Thyroid gland development in a neotenic goby (ice goby, Leucopsarion petersii) and a common goby (ukigori, Gymnogobius urotaenia) during early life stages.

In order to study the characteristics of neoteny in teleosts, development of the thyroid system and digestive tract of a neotenic goby (ice goby, Leucopsarion petersii) and a non-neotenic goby (ukigori, Gymnogobius urotaenia) were compared. In juvenile ukigori, the intestine was found to be convoluted once in the antero-midpart, and gastric glands were present. In the ice goby, the alimentary canal was straight, and no gastric gland was observed even in adult, suggesting that the ice goby retains larval features, not only in appearance but also in internal organs. A marked difference was also found in the thyroid system. In ukigori, activity of the thyroid gland and thyroid stimulating hormone (TSH) cells increased between flexion and postflexion larval phases. However, in the ice goby, thyroid glands remained inactive, and no TSH cells were observed. A delayed development of the thyroid system was suggested as a major factor contributing to neoteny in the ice goby.

Animals↗
PubMed2002

A functional role of Stat3 in in vivo megakaryopoiesis.

The signal transducer and activator of transcription 3 (Stat3), a member of the Stat family of proteins, is commonly activated by thrombopoietic cytokines including thrombopoietin (TPO), interleukin (IL)-6, and interleukin-11. This finding strongly suggested that Stat3 has an important role in megakaryopoiesis and thrombopoiesis. To clarify the functional role of Stat3 in in vivo megakaryopoiesis and thrombopoiesis, we generated transgenic mice overexpressing a dominant-negative Stat3, Stat3F, to suppress the function of endogenous Stat3. To accomplish the selective expression of Stat3F in megakaryocytic lineage cells, we used the regulatory gene region of GATA-1 transcription factor selectively expressed in megakaryocytic and erythroid lineage cells. Two independent transgenic (Tg) mice lines were established. It was confirmed by Western blotting analysis that Stat3F proteins were highly expressed in the platelets from the Tg mice. In addition, it was found that Stat3 activation induced by TPO stimulation was drastically suppressed in these Tg mice compared with littermates. These findings indicate that Stat3F works well in the Tg mice. Platelet counts were within the normal range in steady-state conditions and were recovered normally from transient thrombocytopenia induced by antiplatelet serum injection. Interestingly, the platelet recovery from myelosuppression after 5-fluorouracil treatment was significantly delayed in the Tg mice. Collectively, our results strongly suggest that Stat3 plays an important role in the early stage of megakaryopoiesis, presumably through the expansion of megakaryocytic progenitor cells.

Animals↗
PubMed2002

Identification of the human erythropoietin receptor region required for Stat1 and Stat3 activation.

Signal transducers and activators of transcription (Stat) proteins play important roles in the regulation of hematopoiesis as downstream molecules of cytokine signal transduction. It was previously demonstrated that erythropoietin (EPO), a major regulator of erythropoiesis, activates 3 different Stat members, Stat1, Stat3, and Stat5, in a human EPO-dependent cell line, UT-7/EPO. To clarify the mechanism by which EPO activates Stat1 and Stat3 via the EPO receptor (EPOR), a series of chimeric receptors was constructed bearing the extracellular domain of the granulocyte colony-stimulating factor receptor linked to the transmembrane domain of EPOR and the full length or several mutants of the cytoplasmic domain of EPOR, and these chimeric receptor complementary DNAs were introduced into UT-7/EPO cells. Tyr432 on human EPOR was important for activation of Stat1 and Stat3 and c-myc gene induction. In addition, Jak2 and Fes tyrosine kinases were involved in EPO-induced activation of Stat1 and Stat3. These results indicate that Stat1 and Stat3 are activated by EPO via distinct mechanisms from Stat5.

Cell Division↗
PubMed2002

Chlamydia pneumoniae seropositivity predicts the risk of restenosis after percutaneous transluminal coronary angioplasty.

This study was done to evaluate whether anti-Chlamydia pneumoniae seropositivity can be a predictor of restenosis after coronary intervention. Recent studies indicate that latent infection with C. pneumoniae is associated with and could possibly cause atherosclerosis. However, it is unknown whether chronic infection with this microorganism is involved in the mechanism of restenosis after percutaneous transluminal coronary angioplasty. We prospectively studied 78 consecutive patients (90 target lesions) with symptomatic coronary artery disease who underwent successful coronary intervention to a de novo lesion (conventional balloon angioplasty to 31 lesions and stent implantation to 59 lesions). At angioplasty, blood samples were collected to measure the serum level of anti-C. pneumoniae IgG to examine whether seropositive patients were prone to restenosis and whether the seropositivity could predict the risk of restenosis determined by follow-up coronary angiography performed within 6 months after the angioplasty. Restenosis, defined as more than 50% stenosis with an increase of 15% or more in the degree of stenosis from that measured on cineangiograms after angioplasty, developed in 36 of 62 seropositive patients and in 4 of 16 seronegative patients (58% vs 25%, P = 0.025). Lesions in the seropositive patients had a greater mean loss index (mean +/- SD 0.75 +/- 0.45 vs 0.35 +/- 0.41, P < 0.001), which was defined as late loss (luminal diameter reduction at follow-up angiography) divided by acute gain (luminal diameter gain by angioplasty), in late loss (1.07 +/- 0.64mm vs 0.65 +/- 0.79mm, P = 0.019), in percentage of diameter stenosis (57% +/- 20% vs 41% +/- 21%, P = 0.003) and a lesser mean in minimal luminal diameter (1.18 +/- 0.58 mm vs 1.67 +/- 0.63 mm, P = 0.002) at follow-up angiography. In a multivariate logistic regression model, anti-C. pneumoniae IgG seropositivity was a strong independent predictor of restenosis compared to the other risk factors (odds ratio = 6.2, P = 0.01). C. pneumoniae could play an important role in the mechanism of restenosis and evaluation of the IgG seropositivity, and may help to identify patients at high risk for restenosis.

Aged↗
PubMed2002

Isolation and characterization of a Japanese flounder clonal line, reversed, which exhibits reversal of metamorphic left-right asymmetry.

We have isolated a clonal line reversed (rev) of homozygous Japanese flounder through gynogenesis. The homozygous offspring gynogenetically produced from rev exhibited reversal of organization of the metamorphic L/R asymmetry such as the direction of eye-migration at a high frequency (20-30%). The molecular analysis using a left-specific marker pitx2 revealed that the embryonic L/R axis was ambiguously established: in more than half of rev embryos, pitx2 was expressed bilaterally in the lateral plate mesoderm (LPM). Previous studies in other animals demonstrated that ectopic pitx2 expression in the LPM could cause laterality defects of the visceral organs. Likewise, our results using rev imply that bilateral pitx2 expression could lead to randomization of the visceral organs. Coincidence of ectopic pitx2 expression and reversal of the direction of eye-migration in the population of rev offspring suggests that the rev locus is critical in specification of both the metamorphic and the visceral L/R asymmetries. However, reversal of the sidedness of the orientation of the visceral organs was not always accompanied by reversal of the direction of metamorphic eye-migration, suggesting that different mechanisms should be involved downstream of the rev locus in directing these two phases of asymmetric morphogenesis in the Japanese flounder.

Amino Acid Sequence↗