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Biomedical subjects

T Asaka

Publications and source records attributed to T Asaka.

At least 19 recordsLinked to original sources
PubMed2002

Ferromagnetic domain structures and nanoclusters in Nd(1/2)Sr(1/2)MnO3.

Magnetic domain structures of Nd(1/2)Sr(1/2)MnO3 were investigated by means of low-temperature Lorentz electron microscopy. On cooling, magnetic domain walls started to appear at 250 K, and they were oriented straight along the [100] and [110] directions. With a further decrease in temperature, the volume of each magnetic domain increased with discontinuous domain-wall jumps. A characteristic granular image was observed at around 140 K, near the charge-ordering transition temperature. We consider that this originated from ferromagnetic nanoclusters that appeared in the antiferromagnetic matrix.

Journal Article↗
PubMed2002

Charge/orbital ordering structure of Pr(1-x)Ca(x)MnO(3)(x = 3/8) examined by low-temperature transmission electron microscopy.

The structural phase transition of Pr(1-x)Ca(x)MnO(3)(x = 3/8) was investigated by means of low-temperature transmission electron microscopy. Superlattice reflection spots with a modulation wave vector q(1) = (0,1/2,0) appeared below 230 K, indicating formation of the d(3x(2-r(2))/d(3y(2)-r(2)) type of charge/orbital ordering. Below 150 K, a new series of superlattice reflection spots with a modulation wave vector q(2) = (1/4,1/4,1/2) appeared, suggesting an additional ordering of excess 1/8 Mn(3+), necessary due to the deviation of x from 1/2, with the occupation of the d(3z(2-r(2)) type of e(g) orbital.

Journal Article↗
PubMed2001

Synthesis and antibacterial activity of acylides (3-O-acyl-erythromycin derivatives): a novel class of macrolide antibiotics.

Introduction of an acyl group to the 3-O-position of erythromycin A derivatives instead of L-cladinose led to a novel class of macrolide antibiotics that we named "acylides". The 3-O-nitrophenylacetyl derivative TEA0777 showed significantly potent activity against not only erythromycin-susceptible Gram-positive pathogens but also inducibly macrolides-lincosamides-streptogramin B (MLS(B))-resistant Staphylococcus aureus and efflux-resistant Streptococcus pneumoniae. These results indicated that acylides have potential as next-generation macrolide antibiotics.

Animals↗
PubMed2001

Homozygosity and linkage disequilibrium mapping of autosomal recessive distal myopathy (Nonaka distal myopathy).

Autosomal recessive distal myopathy or Nonaka distal myopathy (NM) is characterized by its unique distribution of muscular weakness and wasting. The patients present with spared quadriceps muscles even in a late stage of the disease. The hamstring and tibialis anterior muscles are affected severely in early adulthood. We have localized the NM gene to the region between markers D9S319 and D9S276 on chromosome 9 by linkage analysis. To further refine the localization of the NM gene, we conducted homozygosity and linkage disequilibrium analysis for 14 patients from 11 NM families using 18 polymorphic markers. All of the patients from consanguineous NM families were found to be homozygous for six markers located within the region between markers D9S2178 and D9S1859. We also provided evidence for significant allelic associations between the NM region and five marker loci. Examination of the haplotype analysis identified a predominant ancestral haplotype comprising the associated alleles 199-160-154-109 (marker order: D9S2179-D9S2180-D9S2181-D9S1804), present in 60% of NM chromosomes and in 0% of parent chromosomes. On the basis of the data obtained in this study, the majority of NM chromosomes were derived from a single ancestral founder, and the NM gene is probably located within the 1.5-Mb region between markers D9S2178 and D9S1791.

Adult↗
PubMed2001

Light element analysis in oxycarbonate superconductors using EELS.

Elemental analysis in an oxycarbonate superconductor ((Cu,N,C)Sr2CaCu2Oy) is conducted using transmission electron microscope-electron energy-loss spectroscopy with detector-gain correction. The gain correction enables highly sensitive elemental analysis and precise measurement of energy-loss near edge structures (ELNESs). It is found that carbon is included as a CO3 group, because the carbon K-edge in the oxycarbonate shows the same ELNES observed from CaCO3. Nitrogen ELNES is similar to that of Sr(NO3)2, so nitrogen is contained as a NO3 group. Although both CO3(2-) and NO3- have similar planar atomic arrangements, the nitrogen ELNES observed is different from that of carbon. EEL spectrum simulation based on DV-Xalpha method is used to interpret the difference.

Journal Article↗
PubMed2001

HRTEM study of new series of oxycarbonitrate superconductors (Cu,C,N)Sr2Ca(n - 1)Cu(n)O(y) (n = 1-6).

Arrangements of Cu and anion groups (CO3 and NO3) in the charge-reservoir (CR) blocks of a series of new oxycarbonitrate superconductors (Cu,C,N)Sr2Ca(n - 1)Cu(n)O(y) (n = 1-6) were examined by means of electron diffraction and high-resolution transmission electron microscopy (HRTEM). The first three members with n = 1-3 [Tc = 33 K (n = 1), 91 K (n = 2), 90 K (n = 3)] show the 4a0-type superstructures with periodic arrangements, [-Cu-X-X-X-Cu-X-X-X-Cu-] (X = CO3, NO3), in the CR blocks. The third member (n = 3) partly contains the 2a0-type of superstructure with [-Cu-X-Cu-X-Cu] in the CR blocks. The fourth member with n = 4 (Tc = 113 K) contains only the 2a0-type of superstructure. The higher members, with n = 5 (Tc = 65 K) and n = 6 (Tc = 52 K), show no evidence of ordering in the CR blocks, suggesting random arrangements of Cu and anion groups.

Journal Article↗
PubMed2001

Synthesis and antibacterial activity of the tricyclic ketolides TE-802 and its analogs.

The novel 6-O-methyl tricyclic ketolides TE-802 and its analogs were synthesized by two successive cyclization reactions, 11,12-cyclic carbamate formation by intramolecular Michael addition and 9,11-diazaheptene ring construction by intramolecular dehydration reaction. These new tricyclic ketolides exhibited good in vitro antibacterial activity against not only erythromycin-susceptible strains but also erythromycin-resistant Staphylococcus aureus and Streptococcus pneumoniae, which are problematic pathogens of nosocomial and community-acquired respiratory tract infections, respectively.

Anti-Bacterial Agents↗
PubMed1999

Borate-rhamnogalacturonan II bonding reinforced by Ca2+ retains pectic polysaccharides in higher-plant cell walls

The extent of in vitro formation of the borate-dimeric-rhamnogalacturonan II (RG-II) complex was stimulated by Ca2+. The complex formed in the presence of Ca2+ was more stable than that without Ca2+. A naturally occurring boron (B)-RG-II complex isolated from radish (Raphanus sativus L. cv Aokubi-daikon) root contained equimolar amounts of Ca2+ and B. Removal of the Ca2+ by trans-1,2-diaminocyclohexane-N,N,N',N'-tetraacetic acid induced cleavage of the complex into monomeric RG-II. These data suggest that Ca2+ is a normal component of the B-RG-II complex. Washing the crude cell walls of radish roots with a 1.5% (w/v) sodium dodecyl sulfate solution, pH 6.5, released 98% of the tissue Ca2+ but only 13% of the B and 22% of the pectic polysaccharides. The remaining Ca2+ was associated with RG-II. Extraction of the sodium dodecyl sulfate-washed cell walls with 50 mM trans-1,2-diaminocyclohexane-N, N,N',N'-tetraacetic acid, pH 6.5, removed the remaining Ca2+, 78% of B, and 49% of pectic polysaccharides. These results suggest that not only Ca2+ but also borate and Ca2+ cross-linking in the RG-II region retain so-called chelator-soluble pectic polysaccharides in cell walls.

Journal Article↗
PubMed1998

[A longitudinal cohort study on the relation between physical condition and masticatory ability in the elderly].

The present study was conducted to determine the relation between physical condition and masticatory ability. The subjects were residents over 65 years old living in three different areas in Sagae City. The physical conditions assessed were height, weight, rate of body fat, grip strength, and bone mineral density. Masticatory ability was evaluated by the test jelly method. The results were as follows: 1) There was a difference in physical condition among subjects from the three residential areas. 2) For males, the group who maintained their masticatory ability exhibited better physical condition than those who did not. As for females, however, the physical condition was more strongly affected by age than masticatory ability.

Aged↗
PubMed1997

Mechanism of mustard oil-induced skin inflammation in mice.

We examined the mechanism of the inflammatory response induced by topical application of mustard oil (0.5-20.0%/20 microliters per ear) to the mouse ear compared to that of the response to capsaicin. The dose-dependent increases in plasma extravasation and ear thickness reached a maximum at approximately 30 min after mustard oil application. Topical pretreatment of ears with capsaicin (250 micrograms/ear) diminished mustard oil-induced plasma extravasation for up to day 7 but not at day 14 after treatment. However, desensitization of the exudative response was not evoked by reapplication of mustard oil to ears. The inflammatory response to mustard oil did not differ between the ears of mast cell-deficient mice and those of the congenic normal mice. Mustard oil-induced plasma extravasation was unaffected by pretreatment with histamine H1 and 5-HT2 receptor antagonists and the capsaicin-functional inhibitor, ruthenium red, which inhibit capsaicin-induced ear oedema. The endopeptidase inhibitor, phosphoramidon, enhanced the ability of mustard oil to increase dye leakage. The tachykinin NK1 receptor antagonist, SR 140333 ((S)1-[2-[3-(3,4-dichlorophenyl)-1-(3-isopropoxyphenylacetyl)pi peridin-3-yl]ethyl]-4-phenyl-1-azoniabicyclo[2.2.2.]octane, chloride), not only inhibited mustard oil-induced plasma extravasation but also blocked the enhancement by phosphoramidon of the response to mustard oil. In contrast, the tachykinin NK2 receptor antagonist, SR 48968 ((S)-N-methyl-N[4-(4-acetylamino-4-phenylpiperidino)-2-(3,4,- dichlorophenyl)butyl]benzamide), and the tachykinin NK3 receptor antagonist, SR 142801 ((S)-(N)-(1-(3-(1-benzoyl-3-(3,4-dichlorophenyl)piperidin-3-yl)pro pyl)-4- phenylpiperidin-4-yl)-N-methylacetamide), had no effect on plasma extravasation. The present results demonstrated that mustard oil induces mouse skin inflammation through a mechanism different from that for capsaicin. Mediators such as histamine and 5-HT from mast cells appear to be minor factors in the response to mustard oil. In addition, evidence supports the assumption that the tachykinin NK1 receptor is involved in this model.

Administration, Topical↗
PubMed1997

Gene locus for autosomal recessive distal myopathy with rimmed vacuoles maps to chromosome 9.

Distal myopathy with rimmed vacuoles is an autosomal recessive muscular disorder, characterized clinically by weakness of the distal muscles in the lower limbs in early adulthood. Recently, the gene locus for familial vacuolar myopathy with autosomal recessive inheritance (hereditary inclusion body myopathy) was mapped to chromosome 9 by genome-wide linkage analysis of nine Persian-Jewish families. Since both disease conditions share similar clinical, genetic, and histopathological features, we analyzed seven families with distal myopathy with rimmed vacuoles using ten microsatellite markers within the region of the hereditary inclusion body myopathy locus. Significantly high cumulative pairwise lod scores were obtained with three markers: D9S248 (Z(max) = 5.90 at theta = 0), D9S43 (Z(max) = 5.25 at theta = 0), and D9S50 (Z(max) = 4.23 at theta = 0). Detection of obligate recombination events as well as multipoint linkage analysis revealed that the most likely location of the distal myopathy with rimmed vacuoles gene is in a 23.3-cM interval defined by D9S319 and D9S276 on chromosome 9. The results raise the possibility that distal myopathy with rimmed vacuoles and hereditary inclusion body myopathy in Persian Jews are allelic diseases.

Adult↗
PubMed1997

[Distribution of Candida species and mutans streptococci related to oral conditions in elderly persons].

The purpose of this investigation was to find the relationship between the occurrence of Candida species and mutans streptococci at 7 sites (saliva, tongue, mucosa, teeth, clasp, external, and mucosal denture surfaces) in the mouth of 97 elderly persons (males: 43, age: 76.4 +/- 6.7 years; females: 54, age: 75.0 +/- 6.6 years). Among the subjects, there were complete denture wearers (n = 20), partial denture wearers (n = 45), and non-denture wearers (n = 32). Candida species were more significantly (p < 0.001) predominant in complete and partial denture wearers (80% each) than in non-denture (18.8%) wearers. The presence of Candida was highest on the mucosal denture surfaces followed by clasp, tongue, and remaining teeth in that order. Positive correlation were significantly found between the CFU numbers of Candida species and mutans streptococci present on the external surfaces (p < 0.001), natural teeth (p < 0.001), clasp (p < 0.01), and saliva (p < 0.05). A negative correlation (r = -0.503; p < 0.001) was found between the number of teeth and the CFU numbers of Candida species. Moreover, the CFU numbers of both groups of microorganisms also increased in 80-year-old and over persons. Candida species were most predominantly found in persons with poor oral and denture cleanliness.

Age Factors↗
PubMed1996

Immunolocalization of transforming growth factor-beta in the bone tissue.

Fetal mouse calvarias were cultured in a medium containing fetal calf serum, 1,25(OH)2D3 and parathyroid hormone in 5% CO2 incubator at 37 degrees C for 5 days. The calvarias were then fixed in a buffered paraformaldehyde solution and the periostea were removed. A polyclonal antibody against transforming growth factor-beta (TFG-beta) and a second antibody labeled with fluorescein isothiocyanate were used to detect TGF-beta. As a result, a specific staining was observed only in the shielding zone covered by osteoclasts in the bone resorption lacunae and in the extracellular matrix adjacent to the osteoclasts. These findings suggested the local delivery and possible activation of TGF-beta by osteoclasts in tissue.

Animals↗
PubMed1996

Tuberculous tenosynovitis in the elbow joint.

A 74-year-old woman was noted to have a mass lesion near the right elbow joint during medication for pulmonary tuberculosis. After discontinuation of medication, the mass gradually became enlarged with swelling and tenderness of the joint. Radiological evaluation disclosed tenosynovitis with an encapsulated abscess. Microscopic examination and culture of an aspiration biopsy specimen from the abscess showed no microorganisms. However, DNA extracted from the specimen contained mycobacterium tuberculosis DNA, permitting a diagnosis of tuberculous tenosynovitis. Mycobacterium is not always detected in biopsy specimens of tuberculous arthritis and tenosynovitis. In such cases, genetic diagnosis may be of great use.

Abscess↗
PubMed1995

Germanium intoxication with sensory ataxia.

Sensory ataxia in inorganic germanium intoxication is rare. A 63-year-old housewife had taken inorganic germanium preparations at a dosage of 36 mg a day for about 6 years (total dose about 80 g). She subsequently developed difficulty in writing and gait disturbance with peripheral neuropathy and renal involvement. Germanium, which is not usually detected in the non-germanium user, was accumulated in her hair and nails, permitting a diagnosis of inorganic germanium intoxication. The peripheral neuropathy and renal injury were not reversible after discontinuing the preparation. Pneumonia and sepsis then supervened and the patient died. Autopsy findings showed degeneration and loss of the dorsal root ganglion cells and degeneration of the dorsal column of the spinal cord. Two previously reported cases presented with ataxia. These patients took germanium for long periods and/or large quantities like our case. It was supposed that sensory ataxia was induced by chronic and dose dependent toxicity of inorganic germanium.

Aged↗