Biomedical subjects

M Takai

Publications and source records attributed to M Takai.

At least 19 recordsLinked to original sources

PubMed2004

Experimental concept for examination of biological effects of magnetic field concealed by gravity.

Space is not only a place to study biological effects of gravity, but also provides unique opportunities to examine other environmental factors, where the biological actions are masked by gravity on the ground. Even the earth's magnetic field is steadily acting on living systems, and is known to influence many biological processes. A systematic survey and assessment of its action are difficult to conduct in the presence of dominant factors, such as gravity. Investigation of responses of biological systems against the combined environment of zero-gravity and zero-magnetic field might establish the baseline for the analysis of biological effects of magnetic factors. We propose, in this paper, an experimental concept in this context, together with a practical approach of the experiments, both in orbit and on the ground, with a thin magnetic shielding film. Plant epicotyl growth was taken as an exemplar index to evaluate technical and scientific feasibility of the proposed system concept.

Cotyledon↗

PubMed2002

Abutment region dosimetry for the monoisocentric three-beam split field technique in the head and neck region using asymmetrical collimators.

Creating non-divergent field edges using asymmetric collimators and a single isocentre can improve matchline dosimetry owing to decreased reliance on operator skills and avoidance of couch movement. However, asymmetic jaws have an associated tolerance that can cause abutment to be misaligned. The matching area dose for monoisocentric three-beam split fields commonly used in head and neck cancer treatments using mismatched and matched collimators is the subject of this work. X-ray verification film was exposed in a solid-water phantom, and the dose at the matching area was evaluated using mismatched and matched collimators. In the case of mismatched (consistently overlapped) collimators, digital displays of an asymmetric collimator position within the tolerance indicated in the manufacturer's specifications were investigated for the three-beam split field technique. The effect of this technique on the junctional dose was also determined using matched collimators. Although the collimators showed a consistent overlap, a perfect dose distribution could be obtained at the matching area. The three-beam split field technique yielded an 8% overdose at the matchline using matched collimators. In conclusion, an awareness of the effects of the abutting technique and digital display tolerance is necessary to achieve good junction uniformity using asymmetric collimators.

Film Dosimetry↗

PubMed2001

Cloning and sequencing of the beta-glucosidase gene from Acetobacter xylinum ATCC 23769.

The beta-glucosidase gene (bglxA) was cloned from the genomic DNA of Acetobacter xylinum ATCC 23769 and its nucleotide sequence (2200 bp) was determined. This bglxA gene was present downstream of the cellulose synthase operon and coded for a polypeptide of molecular mass 79 kDa. The overexpression of the beta-glucosidase in A. xylinum caused a tenfold increase in activity compared to the wild-type strain. In addition, the action pattern of the enzyme was identified as G3ase activity. The deduced amino acid sequence of the bglxA gene showed 72.3%, 49.6%, and 45.1% identity with the beta-glucosidases from A. xylinum subsp. sucrofermentans, Cellvibrio gilvus, and Mycobacterium tuberculosis, respectively. Based on amino acid sequence similarities, the beta-glucosidase (BglxA) was assigned to family 3 of the glycosyl hydrolases.

Amino Acid Sequence↗

PubMed2001

Role of Notch-1 intracellular domain in activation of rheumatoid synoviocytes.

OBJECTIVE: Notch family proteins are transmembrane receptors that control cell fate and proliferation. Rheumatoid arthritis (RA) is characterized by activation and abnormal proliferation/differentiation of synoviocytes. We examined the expression of Notch-1 and its role in the activation of RA synoviocytes. METHODS: The expression of Notch-1 protein was detected by a specific antibody raised against the Notch-1 intracellular domain. Notch-1 messenger RNA (mRNA) expression in synoviocytes was analyzed by Northern blotting. Notch-1 protein expression was confirmed by Western blotting with anti-Notch-1 antibody. To analyze the role of Notch-1 in synoviocyte proliferation, we examined the effects of antisense Notch-1 oligonucleotides (ODNs) and MW167, a gamma-secretase inhibitor. RESULTS: Notch-1 protein and mRNA were detected in synovium from all study subjects. The nucleus of RA synoviocytes showed strong staining with anti-Notch-1 antibody, whereas there was predominantly cytoplasmic staining of normal and osteoarthritis (OA) synoviocytes. Western blotting showed a distinct approximately 63-kd protein detected by anti-Notch-1 antibody in nuclear extracts from RA synoviocytes, indicating that nuclear staining of RA synovium and synoviocytes is likely to be the result of nuclear localization of Notch-1 intracellular domain (NICD). Furthermore, tumor necrosis factor alpha (TNFalpha) increased NICD nuclear translocation in a dose-dependent manner. Antisense Notch-1 ODNs partially blocked the proliferation of RA synoviocytes and inhibited TNFalpha-induced proliferation in both OA and RA synoviocytes. In addition, gamma-secretase inhibitor, which blocks the production of NICD, also inhibited TNFalpha-induced proliferation of RA synoviocytes. CONCLUSION: Our results demonstrate the expression of Notch-1 in synoviocytes and the presence of Notch-1 fragment in the nuclei of RA synoviocytes and suggest the involvement of Notch-1 signaling in the TNFalpha-induced proliferation of RA synoviocytes.

Amyloid Precursor Protein Secretases↗

PubMed2001

A new anthropoid from the latest middle Eocene of Pondaung, central Myanmar.

A new genus and species of medium-sized fossil primate, Myanmarpithecus yarshensis, is described from the lastest middle Eocene sediments of Pondaung, central Myanmar (Burma). The specimens consist of right maxillary fragments with P(4)-M(3)and a left mandibular corpus with C-P(3)and M(2-3). To date, three purported anthropoids have been discovered from the Pondaung Formation: Pondaungia and Amphipithecus (Amphipithecidae) and Bahinia (Eosimiidae). Myanmarpithecus differs from these other Pondaung primates in having cingular hypocones on upper molars and in lacking paraconids on M(2-3). Although Myanmarpithecus resembles some utahiin omomyines in superficial aspects of the morphology of M(2-3)(i.e., mesiodistally compressed molar trigonid and enamel crenulation), the morphological analysis of upper molars and lower premolars indicates that it is neither an omomyoid nor an adapoid but is more derived than fossil prosimians (such as adapoids, omomyoids, and tarsiers) and more anthropoid-like. On the other hand, it is more primitive (prosimian-like) than early anthropoids from the late Eocene/early Oligocene of the Fayum, Egypt. Myanmarpithecus is likely to be an early, primitive anthropoid ("protoanthropoid").

Animals↗

PubMed2001

A new iron oxidase from a moderately thermophilic iron oxidizing bacterium strain TI-1.

Iron oxidase was purified from plasma membranes of a moderately thermophilic iron oxidizing bacterium strain TI-1 in an electrophoretically homogeneous state. Spectrum analyses of purified enzyme showed the existence of cytochrome a, but not cytochrome b and c types. Iron oxidase was composed of five subunits with apparent molecular masses of 46 kDa (alpha), 28 kDa (beta), 24 kDa (gamma), 20 kDa (delta), and 17 kDa (epsilon). As the molecular mass of a native enzyme was estimated to be 263 kDa in the presence of 0.1% n-dodecyl-beta-D-maltopyranoside (DM), a native iron oxidase purified from strain TI-1 seems to be a homodimeric enzyme (alpha beta gamma delta epsilon)(2). Optimum pH and temperature for iron oxidation were pH 3.0 and 45 degrees C, respectively. The K(m) of iron oxidase for Fe(2+) was 1.06 mM and V(max) for O(2) uptake was 13.8 micromol x mg(-1) x min(-1). The activity was strongly inhibited by cyanide and azide. Purified enzyme from strain TI-1 is a new iron oxidase in which electrons of Fe(2+) were transferred to haem a and then to the molecular oxygen.

Electrophoresis, Polyacrylamide Gel↗

PubMed2001

Focal segmental glomerulosclerosis associated with acromegaly.

Experimental studies in rats have demonstrated an association between focal segmental glomerulosclerosis (FSGS) and growth hormone, but patients with FSGS complicating acromegaly are very rare. In this report we present a case of FSGS associated with acromegaly. With a long history of soft tissue swelling of hands and feet, elevated plasma growth hormone levels and other biochemical abnormalities, a 53-year old male had suffered from acromegaly for over 15 years. He had moderate proteinuria for 6 years, but never evidenced nephrotic syndrome. A renal biopsy specimen revealed FSGS and glomerular hypertrophy. Trans-sphenoidal surgical removal of the pituitary adenoma resulted in the normalization of elevated growth hormone and insulin-like growth factor I levels, but proteinuria continued. This case suggests that the overproduction of growth hormone may participate, at least in part, in the development of human FSGS. It is possible that once FSGS is present in an acromegalic patient, cessation of GH overproduction may not be enough to reverse it.

Acromegaly↗

PubMed2000

Cloning and sequencing of the levansucrase gene from Acetobacter xylinum NCI 1005.

The levansucrase gene (lsxA) was cloned from the genomic DNA of Acetobacter xylinum NCI 1005, and the nucleotide sequence of the lsxA gene (1,293 bp) was determined. The deduced amino acid sequence of the lsxA gene showed 57.4% and 46.2% identity with the levansucrases from Zymomonas mobilis and Erwinia amylovora, respectively, while only 35.2% identity with that from Acetobacter diazotrophicus. The gene product of lsxA (LsxA) that was overproduced in E. coli coded for a polypeptide of molecular mass 47 kDa. The LsxA released glucose and produced polysaccharide from sucrose, the structure of which was analyzed by nuclear magnetic resonance spectroscopy and determined to be a beta-(2,6)-linked polyfructan.

Amino Acid Sequence↗

PubMed2000

A novel female-specific member of the CYP3A gene subfamily in the mouse liver.

Expression of a female-specific CYP3A in the adult mouse liver was observed on immunoblotting analysis. To characterize this cytochrome P450, we determined the primary structure of its cDNA and examined its expression profile. This cytochrome P450 consisted of 504 amino acids and showed 92, 68, 88, and 69% amino acid sequence identity with mouse CYP3A11, 3A13, 3A16, and 3A25, respectively, and was designated as CYP3A41, a new mouse CYP3A gene. In the female liver, levels of CYP3A41 mRNA expression were comparable to those of CYP3A11, the major CYP3A enzyme in the adult mouse liver. Expression of CYP3A41 mRNA was detected immediately after birth in the livers of animals of both sexes, but increased with age in females, whereas it was gradually reduced in males, resulting in predominantly female-specific expression in livers. Lesser amounts of CYP3A41 mRNA were detected in the kidneys of female mice, with traces in the stomach, ovary, and heart of female mice and in the testis of male mice. Gonadectomy and sex hormone treatment indicated that estradiol and testosterone were able to induce and suppress the expression of CYP3A41 mRNA in the liver, respectively. Among the classical CYP3A inducers, dexamethasone, rifampicin, and 3-methylcholanthrene did not affect the level of CYP3A41 mRNA in the liver of either sex. On the other hand, pregnenolone 16alpha-carbonitrile and phenobarbital suppressed CYP3A41 level to half that of untreated female mice. These observations indicated that CYP3A41 is a female-specific CYP3A and one of the major CYP3A forms in the female mouse liver.

Amino Acid Sequence↗

PubMed2000

The transition state in the folding-unfolding reaction of four species of three-disulfide variant of hen lysozyme: the role of each disulfide bridge.

The effects of lacking a specific disulfide bridge on the transition state in folding were examined in order to explore the folding-unfolding mechanism of lysozyme. Four species of three-disulfide variant of hen lysozyme (3SS-lysozyme) were prepared by replacing two Cys residues with Ala or Ser: C6S/C127A, C30A/C115A, C64A/C80A and C76A/C94A. The recombinant hen lysozyme was studied as the standard reference containing four authentic disulfide bridges and the extra N-terminal Met: the recombinant hen lysozyme containing the extra N-terminal. Folding rates were measured by monitoring the change in fluorescence intensity associated with tri-N-acetyl-d-glucosamine binding to the active site of refolded lysozyme. It was confirmed that the folding rate of the recombinant hen lysozyme containing the extra N-terminal was the same as that of wild-type lysozyme, and that the folding rate was little affected by the presence of tri-N-acetyl-d-glucosamine (triNAG). The folding rate of C64A/C80A was found to be the fastest and almost the same as that of the recombinant hen lysozyme containing the extra N-terminal, and that of C30A/C115A the second, and that of C6S/C127A the third. The folding rate of C76A/C94A was particularly slow. On the other hand, the unfolding rates which were measured in the presence of triNAG showed the dependence on the concentration of triNAG. The intrinsic unfolding rate in the absence of triNAG was determined by extrapolation. Also in the unfolding rate, C76A/C94A was markedly slower than the others. It was found from the analysis of binding constants of triNAG to C64A/C80A during the unfolding process that the active site of C64A/C80A partly unfolds already prior to the unfolding transition. On the basis of these kinetic data, we suggest that C64A/C80A folding transition can occur with leaving the loop region around SS3 (C64-C80) flexible, while cross-linking by SS4 (C76-C94) is important for the promotion of folding, because it is an indispensable constraint on the way towards the folding transition state.

Amino Acid Substitution↗

PubMed2000

New fossil materials of the earliest new world monkey, Branisella boliviana, and the problem of platyrrhine origins.

Branisella boliviana, from the Late Oligocene of Salla, Bolivia, is the oldest fossil platyrrhine monkey discovered. To date, several fossil specimens of Branisella have been obtained, but most of them are fragmentary dentitions, so the animals craniodental morphology is still obscure. During the 1996 field season a pair of upper and lower jaw fragments and another nearly complete mandible were recovered. These new fossil materials reveal the following morphological features in Branisella: 1) P(2) is much smaller than P(3,4), whereas P(2) is relatively small but probably sexually dimorphic; 2) the zygomatic arch protrudes smoothly posterolaterally from the maxillary bone, as in extant Callicebus; 3) the mandibular arcade is nearly V-shaped and the symphysial angle, which is formed by the horizontal plane and the anterior face of mandibular symphysis, is about 40 degrees, i.e., it neither leans as far anteriorly as in callitrichines nor does it stand as vertically as Cebus; 4) upper and lower molars wore down rapidly in life, suggesting a herbivorous diet and the possibility of terrestriality; and 5) dental eruptive sequence is the same as in extant Aotus. As a whole, the dentition of Branisella is very similar to that of Proteopithecus from the Late Eocene of Fayum, Egypt, except in the lower canine morphology, suggesting a close phyletic relationship between them. The origin and early diversification of platyrrhine monkeys might have occurred on the African continent before crossing the Atlantic Ocean.

Animals↗

PubMed2000

Effects of combinations of anti-rheumatic drugs on the production of vascular endothelial growth factor and basic fibroblast growth factor in cultured synoviocytes and patients with rheumatoid arthritis.

OBJECTIVE: To examine whether different combinations of disease-modifying anti-rheumatic drugs (DMARDs), including bucillamine (BUC), gold sodium thiomalate (GST), methotrexate (MTX), salazosulphapyridine (SASP) and dexamethasone (DEX; a steroid), act by inhibiting the production of vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) in cultured synoviocytes, causing a decrease in their serum concentrations in patients with rheumatoid arthritis (RA). METHODS: The VEGF and bFGF concentrations in cultured synoviocytes and peripheral blood from patients with RA were measured by enzyme-linked immunosorbent assay and their serum concentrations were measured at two time points. RESULTS: BUC and GST inhibited VEGF production even when given alone, and a combination of BUC, GST and MTX with DEX also inhibited VEGF production. None of the DMARDs or DEX inhibited bFGF production when given alone, but a combination of SASP and GST inhibited the production of bFGF in cultured synoviocytes. Serum VEGF concentrations were significantly decreased 6 months after the commencement of medication compared with their concentrations before medication. CONCLUSION: Our results show that the effects of a combination of DEX with any two of BUC, GST, SASP and MTX on the production of VEGF and bFGF in cultured synoviocytes and on the serum concentrations of VEGF in patients with RA may be based on synergistic or additive effects of the drugs.

Anti-Inflammatory Agents↗

PubMed2000

Effects of sulfhydryl compounds on interleukin-1-induced vascular endothelial growth factor production in human synovial stromal cells.

We investigated the effects of various sulfhydryl compounds on interleukin-1 (IL-1)-induced vascular endothelial growth factor (VEGF) production in human synovial stromal cells (HSSC). HSSC stimulated by IL-1beta (100 ng/ml) produced VEGF and interleukin-6 (IL-6) in vitro. Monosulfhydryl compounds, N-acetylcysteine, D-penicillamine, tiopronin and the bucillamine-like disulfhydryl compound, compound A scarcely affected VEGF or IL-6 production at concentrations of 10(-5) and 10(-4) M. However, the disulfhydryl compound, bucillamine inhibited VEGF production but not IL-6 production at concentrations of 10(-5) and 10(-4) M. These results suggest that bucillamine may be a selective inhibitor of IL-1-induced VEGF production in HSSC, and that inhibition of VEGF production may require not only SH groups but also a specific chemical structure.

Acetylcysteine↗

PubMed1999

Transglycosylation of cellobiose by partially purified Trichoderma viride cellulase.

A commercial cellulase from Trichoderma viride was fractionated into three fractions, F1, F2, and F3, in order to investigate transglycosylation activities. Among these fractions, F3, which demonstrated highly hydrolytic activity toward p-nitrophenyl beta-D-glucopyranoside and Avicel, most effectively catalyzed the transglycosylation of cellobiose and converted cellobiose into beta-Glc-(1-->6)-beta-glc-(1-->4)-Glc and beta-Glc-(1-->6)-beta-Glc-(1-->6)-beta-Glc(1-->4)-Glc. The F3 fraction contained the enzyme to catalyze beta-glucosyl transfer toward only the C-6 position of the sugar acceptor, and thus it is expected to be of use for syntheses of functional oligosaccharides.

Carbohydrate Sequence↗

PubMed1999

Conformational studies on the specific cleavage site of Type I collagen (alpha-1) fragment (157-192) by cathepsins K and L by proton NMR spectroscopy.

Cathepsins K and L are cysteine proteinases which are considered to play an important role in bone resorption. Type I collagen is the most abundant component of the extracellular matrix of bone and regarded as an endogenous substrate for the cysteine proteinases in osteoclastic bone resorption. We have synthesized a fragment of Type I collagen (alpha-1) (157-192) as a substrate for the cathepsins and found that cathepsins K and L cleave the fragment at different specific sites. The major cleavage sites for cathepsin K were Met159-Gly160, Ser162-Gly163 and Arg165-Gly166, while those for cathepsin L were Gly166-Leu167 and Gln180-Gly181. The structure of the fragment was analyzed in aqueous solution by circular dichroism and proton NMR spectroscopy and the difference in the molecular recognition of collagen by cathepsins K and L was discussed from the structural aspect.

Amino Acid Sequence↗

PubMed1999

Structural analyses of new tri- and tetrasaccharides produced from disaccharides by transglycosylation of purified Trichoderma viride beta-glucosidase.

A new beta-glucosidase was partially purified from Trichoderma viride cellulase. This beta-glucosidase catalyzed a transglycosylation reaction of cellobiose to give beta-D-Glc-(1-->6)-beta-D-Glc-(1-->4)-D-Glc (1, yield: 18.8%) and beta-D-Glc-(1-->6)-beta-D-Glc-(1-->6)-beta-D-Glc-(1-->4)-D-Glc (2, 3.7%), regioselectively. Furthermore, the enzyme regioselectively converted laminaribiose and gentiobiose into beta-D-Glc-(1-->6)-beta-D-Glc-(1-->3)-D-Glc (3, 15.3%) and beta-D-Glc-(1-->6)-beta-D-Glc-(1-->6)-D-Glc (4, 20.2%), respectively. The structures (1-4) of the products were determined by 1H and 13C NMR spectroscopies. This high regio- and stereoselectively of the beta-glucosidase could be applied for oligosaccharide synthesis.

Carbohydrate Sequence↗

PubMed1999

Inhibitory effects of anti-rheumatic drugs on vascular endothelial growth factor in cultured rheumatoid synovial cells.

Vascular endothelial growth factor (VEGF) is a potent inducer of angiogenesis and is constitutively expressed in the synovium of rheumatoid arthritis (RA). Over-expression of VEGF may play an important role in pathogenic vascularization and synovial hyperplasia of RA. In the present study, we examined whether disease-modifying anti-rheumatic drugs (DMARDs), including bucillamine (BUC), gold sodium thiomalate (GST), methotrexate (MTX) and salazosulfapiridine (SASP), act by inhibiting the production of VEGF by cultured synovial cells of patients with RA. Treatment of cultured synoviocytes with lipopolysaccharide (LPS) significantly increased VEGF production by cultured synovial cells. BUC significantly inhibited LPS-induced VEGF production, while GST tended to inhibit the production of VEGF. The inhibitory effects on VEGF production were dose-dependent. In contrast, MTX and SASP did not affect VEGF production. Reverse transcriptase-polymerase chain reaction (RT-PCR) analysis showed that BUC also inhibited LPS-induced VEGF mRNA expression in RA synovial cells. The present study provides the first evidence that BUC inhibits VEGF production and the expression of its mRNA in synovial cells of RA patients. Our results indicate that the anti-rheumatic effects of BUC are mediated by suppression of angiogenesis and synovial proliferation in the RA synovium through the inhibition of VEGF production by synovial cells.

Antirheumatic Agents↗

PubMed1999

Natural killer (NK) T cells are significantly decreased in the peripheral blood of patients with rheumatoid arthritis (RA).

The number of NK T cells was measured in relation to the Th1/Th2 imbalance observed in RA. Peripheral blood samples of patients with RA (n = 60) and healthy controls (n = 36) were stained with anti-NK receptor 1A (anti-NKR-P1A), anti-CD56, and anti-CD3 MoAbs, and examined by three-colour flow cytometry. NK T (NKR-P1A+CD3+) cells in the peripheral blood were decreased in RA compared with the controls: 25 +/- 20/microl versus 143 +/- 53/microl (P < 0.0001). CD56+CD3+ cells were also decreased in RA: 60 +/- 46/microl versus 116 +/- 54/microl (P < 0.0001). The decrease was significant when adjusted to the number of total lymphocytes (P < 0.0001) or NK (CD56+CD3-) cells (P < 0.0001), and showed no correlation with age, sex, disease duration, disease activity, functional class, x-ray stage, drug treatment, joint score, grip strength, C-reactive protein, rheumatoid factor or erythrocyte sedimentation rate of the patients. The results show that the levels of NK T cells are depressed in the peripheral blood of patients with RA, suggesting that the measurement of NK T cells in peripheral blood may have clinical importance for a Th1-type autoimmune disease like RA.

Age Factors↗