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Biomedical subjects

Y Machida

Publications and source records attributed to Y Machida.

At least 55 records · Page 3Linked to original sources
PubMed1997

Occlusal migration of the maxillary first primary molars subsequent to the loss of antagonists.

The purpose of this study was to observe the vertical changes in unopposed maxillary first primary molars longitudinally. The subjects of this study were 17 children whose lower first primary molars had to be extracted. Space closure were prevented by crown-loop space maintainers for all these children. Plaster casts were made every 4 months for 16 to 24 months after the extraction. These series of casts were standardized, and vertical changes of the maxillary first primary molars against the occlusal plane were measured using a micro-reader. The mean changes indicated that maxillary first primary molars without intercuspidation tend to drift toward the extraction space. On the control side with antagonists, the maxillary first molars seemed to move reversed to apical throughout the observation period. Accordingly, the results of this study showed new trends after the premature loss of primary molars. The vertical changes toward extraction space varied from -0.40 mm to 1.43 mm at the 16 months after extraction. Mean changes were small, but there were some individual differences in reaction, giving negative values. However, we should always be concerned about loss of arch length and also occlusal drift of unopposed teeth, because the vertical changes were greater than 1 mm at 16 months after extraction in some cases.

Child↗
PubMed1997

Prevalence of congenital dental anomalies of the deciduous dentition in Japanese children.

We examined the prevalence of anomalies in deciduous dentition in 2,733 Japanese three-year-old children. The results showed that fused teeth occurs in 4.10%, congenital missing teeth in 2.38%, enamel hypoplasia in 1.50%, peg-shaped teeth in 0.55%, palatal cusps in upper deciduous incisors in 0.37%, supernumerary teeth in 0.07%, and color anomalies in 0.07%. Sixty-nine boys and 43 girls had fused teeth, percentages of 4.88 and 3.26, respectively. This difference was significant. All the fused teeth were located in the anterior region and were more frequent in the mandibular than in the maxillary arch. In the mandibular arch, 50 cases involved the lateral incisor and canine; the central incisor and lateral incisor were fused in 48 instances. There were 30 boys (2.12%) and 35 girls (2.65%) with congenitally missing deciduous teeth. This difference was not significant. Unilateral missing teeth were more frequently observed than bilateral missing ones. The lower lateral deciduous incisor was the most frequently missing tooth. The prevalences of fused teeth and congenital missing teeth were significantly higher in this study than in studies of American and Scandinavian children. These two anomalies are tending to increase in frequency in Japan.

Anodontia↗
PubMed1996

In vivo drug release and antitumor characteristics of water-soluble conjugates of mitomycin C with glycol-chitosan and N-succinyl-chitosan.

The water-soluble conjugates of mitomycin C (MMC) with N-succinyl-chitosan (N-Suc-chitosan) and glycol-chitosan (Gly-chitosan), named N-Suc-chitosan-glu-MMC and Gly-chitosan-glu-MMC, respectively, were characterized mainly by the plasma concentration-time profiles of MMC after intraperitoneal administration and their in vivo antitumor effect against P388 leukemia and Sarcoma 180. Before in vivo evaluation, polymer-drug binding characteristics were checked by gel-chromatography. Gel-chromatographs proposed the covalent binding of 1a-(4-carboxybutyryl)-MMC (glu-MMC) with both the polymer supports. The plasma concentration of MMC showed that each conjugate released MMC in vivo at a similar rate. Kinetic analysis suggested that the in vivo drug release should be considerably faster than the in vitro release in the buffer, pH 7.4, alone. In the treatment against P388 leukemia inoculated intraperitoneally, Gly-chitosan-glu-MMC showed the highest increase in life span (ILS) at 10 mg MMC eq/kg. It was lethally toxic at the dose of 20 mg MMC eq/kg, while N-Suc-chitosan-glu-MMC gave the highest ILS value at this dose. Each conjugate exhibited a little larger ILS value than MMC. For the Sarcoma 180 solid tumor inoculated subcutaneously, the polymer characteristics affected the antitumor effect. Namely, with the intravenous injection, Gly-chitosan-glu-MMC hardly exhibited any tumor growth inhibition, but N-Suc-chitosan-glu-MMC showed significant tumor growth suppression. As to the intratumoral administration, the tendency to suppress tumor growth was observed in MMC and both the conjugates.

Animals↗
PubMed1996

Preparation and drug release characteristics of the conjugates of mitomycin C with glycol-chitosan and N-succinyl-chitosan.

Mitomycin C (MMC) was covalently attached to glycol-chitosan (Gly-chitosan) and N-succinyl-chitosan (N-Suc-chitosan) through a spacer of the glutaryl group, and each conjugate was obtained as a water-soluble product. Stability of 1a-(4-carboxybutyryl)-MMC (Glu-MMC) in vitro was investigated by incubation in 1/15 M phosphate buffers of pH 5, 6, 7.4, 8 and 9 at 37 degrees C. The release rate of MMC from Glu-MMC was very slow at neutral pH, gradual at basic pH and relatively fast at acidic pH, but the quick decomposition of MMC proceeded simultaneously at acidic pH. Release of MMC from the conjugates in vitro was investigated by incubation in 1/15 M phosphate buffers of pH 5, 7.4 and 9 at 37 degrees C. The release rate of MMC from the conjugates was slight at acidic pH, accelerated at basic pH, and was gradual at pH 7.4. In a plasma-buffer (pH 7.4) mixture (1:1, v/v), the release rate of MMC from the conjugates was rather similar to that in only the buffer (pH 7.4).

Antibiotics, Antineoplastic↗
PubMed1996

Phylogenetic position of the Japanese river otter Lutra nippon inferred from the nucleotide sequence of 224 bp of the mitochondrial cytochrome b gene.

A 224 bp fragment of the mitochondrial cytochrome b gene has been amplified from a 30-year-old mummy-like specimen of the Japanese river otter Lutra nippon by polymerase chain reaction (PCR). The amplified products were subcloned in the Smal site of pUC 18 and sequenced. The sequence was different from those of the congeneric Eurasian otters Lutra lutra (Latvia) and Lutra lutra (China) in 7-9 nucleotides, all of which were located at the third position of a codon and identified as transitional differences A<-->G or C<-->T. The phylogenetic analysis using the 224 bp sequences of Lutra nippon, Lutra lutra (Lativa), Lutra lutra (China), Aonyx cinerea (Asian small-clawed otter), Mustela sibirica and Mustela itatsi (weasels) supports the recent morphological study that the Japanese river otter is not a subspecies of Lutra lutra, but a distinct species, Lutra nippon. We found that Lutra nippon and Lutra lutra contain the cytochrome b-like sequences, that appear to be a pseudo-form of cytochrome b gene. The sequences are characterized by the presence of deletion and termination codons by the presence of several types of sequences with minor variations, and by the faster evolutionary rate compared with that of the mitochondrial cytochrome b gene. The genes would present in the nuclear DNA rather than in the mitochondrial DNA, as in the case of the nonfunctional cytochrome b-like sequences previously reported in a rodent.

Animals↗
PubMed1996

[Functional imaging of the sensorimotor cortex using an ultra-fast MR imaging method].

UNLABELLED: The aim of this study was to assess changes in brain activity during a motor task and variable sensory stimulation using echo planar imaging, which represents the fastest clinically usefull imaging technique available. MATERIALS AND METHODS: The subjects of this study were 11 healthy-volunteers, 4 males and 11 females, with an average of 26.4 years. The subjects were instructed to tap the fingers of one hand as the motor task. Compressed air was applied 5 times a second as "simple" sensory stimulation. Simple figures were drawn on the subjects palm as "complex" sensory stimulation. In all cases, functional imaging was performed by T2*-weighted echo planar imaging (TE = 53 msec, TR = 3000 msec, flip angle = 90 degrees, matrix 64 x 64, FOV = 205 mm, slice thickness = 8 mm) alternately at rest and during the task (intervals: 30 sec). A total of 60 images was collected in 3 minutes. Images obtained by subtracting images at rest and during the task were analyzed. RESULTS AND DISCUSSION: Almost all subjects showed a transient signal increase in the contralateral paracentral region during simple sensory stimulation. Continuous signal increases in the contra- and/or ipsi-lateral para-central region were observed during complex sensory stimulation. Some exhibited signal increases in the parietal or frontal association cortex, but they disappeared when subject's attention was distracted during stimulation. All subjects displayed signal increases in the contralateral para-central region during the motor task. Some of them exhibited signal increases in the medial frontal area (supplementary motor area) and ipsilateral para-central region. These results suggest that the signal increases of functional MRI reflect not only simple reactions to stimulation but higher cerebral function as well.

Adult↗
PubMed1996

[Pharmacokinetic and clinical evaluations of azithromycin in the pediatric field].

Azithromycin (AZM), an oral macrolide antibiotic drug, was studied for its efficacy and pharmacokinetics in the treatment of pediatric patients with respiratory tract infections. The results of the study are presented. Fifteen pediatric patients in an age range between 1 and 10 years were given 8.9 to 14.7 mg/ kg body weight of AZM once daily for 3 to 4 days. Pharmacokinetics of AZM in three patients were examined. AZM concentration in plasma was 0.037 microgram/ml at 72 hours after final dosing, while urine concentration was 10.9 micrograms/ml measured during a period between 72 and 96 hours post-dosing. Fourteen patient cases were included in analysis of drug efficacy for AZM. AZM was found "markedly effective" in all seven patients with pneumonia, and "effective" in all three patients with acute bronchitis, two patients with mycoplasmal pneumonia, and one patient with tonsillitis. In one patient with mycoplasmal bronchitis, AZM was found slightly effective. The efficacy rate was 92.9% (13/14). The study found one case of side effect, moderate diarrhea. No laboratory abnormality was documented. In conclusion, an antibiotic AZM was found useful in a treatment of pediatric respiratory tract infections.

Anti-Bacterial Agents↗
PubMed1996

Clinical and histological observations of continuously formed bilateral mandibular deciduous central incisor roots after traumatic coronal destruction.

We encountered a rare case of continuously forming bilateral mandibular deciduous central incisor roots after traumatic coronal destruction. The patient, 3 year 3 month old boy, had sustained an external injury which had caused the crowns of hist bilateral deciduous central incisors to fall out when he was 12 months old. Oral examination revealed two small, hard tissues resembling tooth structures on the alveolar ridge in the area of the lost mandibular central incisors. X-ray examination revealed them to be deciduous central incisor roots. We observed the extracted roots histologically and found that the lesion of the crown fracture and pulpal exposure on these roots was completely covered by newly formed irregular dentin and cementoid tissues. In this case, the causes of the continuous root formation were considered to be that the pulp tissues of traumatized teeth were able survive, so the injured lesion was quickly healed and covered with gingival tissue. The vital pulp produced the reparative hard tissue, sealing the site of pulpal exposure and continuing root formation after the trauma.

Child, Preschool↗
PubMed1995

Visualization of site-specific recombination catalyzed by a recombinase from Zygosaccharomyces rouxii in Arabidopsis thaliana.

Excision of a DNA segment can occur in Arabidopsis thaliana by reciprocal recombination between two specific recombination sites (RSs) when the recombinase gene (R) from Zygosaccharomyces rouxii is expressed in the plant. To monitor recombination events, we generated several lines of transgenic Arabidopsis plants that carried a cryptic beta-glucuronidase (GUS) reporter gene which was designed in such a way that expression of the reporter gene could be induced by R gene-mediated recombination. We also made several transgenic lines with an R gene linked to the 35S promoter of cauliflower mosaic virus. Each transgenic line carrying the cryptic reporter gene was crossed with each line carrying the R gene. Activity of GUS in F1 and F2 progeny was examined histochemically and recombination between two RSs was analyzed by Southern blotting and the polymerase chain reaction. In seedlings and plantlets of F1 progeny and most of the F2 progeny, a variety of patterns of activity of GUS, including sectorial chimerism in leaves, was observed. A small percentage of F2 individuals exhibited GUS activity in the entire plant. This pattern of expression was ascribed to germinal recombination in the F1 generation on the basis of an analysis of DNA structure by Southern blotting. These results indicate that R gene-mediated recombination can be induced in both somatic and germ cells of A. thaliana by cross-pollination of parental transgenic lines.

Arabidopsis↗
PubMed1995

A tobacco protein kinase, NPK2, has a domain homologous to a domain found in activators of mitogen-activated protein kinases (MAPKKs).

A cDNA (cNPK2) that encodes a protein of 518 amino acids was isolated from a library prepared from poly(A)+ RNAs of tobacco cells in suspension culture. The N-terminal half of the predicted NPK2 protein is similar in amino acid sequence to the catalytic domains of kinases that activate mitogen-activated protein kinases (designated here MAPKKs) from various animals and to those of yeast homologs of MAPKKs. The N-terminal domain of NPK2 was produced as a fusion protein in Escherichia coli, and the purified fusion protein was found to be capable of autophosphorylation of threonine and serine residues. These results indicate that the N-terminal domain of NPK2 has activity of a serine/threonine protein kinase. Southern blot analysis showed that genomic DNAs from various plant species, including Arabidopsis thaliana and sweet potato, hybridized strongly with cNPK2, indicating that these plants also have genes that are closely related to the gene for NPK2. The structural similarity between the catalytic domain of NPK2 and those of MAPKKs and their homologs suggests that tobacco NPK2 corresponds to MAPKKs of other organisms. Given the existence of plant homologs of an MAP kinase and tobacco NPK1, which is structurally and functionally homologous to one of the activator kinases of yeast homologs of MAPKK (MAPKKKs), it seems likely that a signal transduction pathway mediated by a protein kinase cascade that is analogous to the MAP kinase cascades proposed in yeasts and animals, is also conserved in plants.

Amino Acid Sequence↗
PubMed1995

DNA rearrangement associated with the integration of T-DNA in tobacco: an example for multiple duplications of DNA around the integration target.

Transferred DNA (T-DNA) of the tumor-inducing (Ti) plasmid is transferred from Agrobacterium tumefaciens to plant cells and is stably integrated into the plant nuclear genome. By the inverse polymerase chain reaction DNA fragments were amplified that contained the T-DNA/plant DNA junctions from the total DNA of a transgenic tobacco plant that had a single copy of the T-DNA in a repetitive region of its genome. A DNA fragment containing the target site was amplified from the total DNA of non-transformed tobacco by the polymerase chain reaction using high-stringency conditions. Comparison of the nucleotide sequence of the target site with those of the T-DNA/plant DNA junctions revealed that various duplications of short stretches of nucleotide sequences around the target and in the incoming T-DNA had accompanied the integration of the T-DNA. A deletion of 16 bp at the target site was also found and the target site was similar, in terms of nucleotide sequence, to regions around the breakpoints of the T-DNA. This finding provides a clear example of the occurrence of complex rearrangements during the integration of T-DNA.

Agrobacterium tumefaciens↗
PubMed1995

Plant homologues of components of MAPK (mitogen-activated protein kinase) signal pathways in yeast and animal cells.

As they respond to numerous extracellular and intracellular stimuli, plants develop various morphological features and the capacity for a large variety of physiological processes during their growth. If we are to understand the molecular basis of such developments, we must elucidate the way in which signals generated by such stimuli can be transduced into plant cells and transmitted by cellular components to induce the appropriate terminal events. In yeast and animal systems, signal pathways that are known collectively as MAPK (mitogen-activated protein kinase) cascades have been shown to play a central role in the transmission of various signals. The components of these pathways include the MAPK family, the activator kinases of the MAPK family (the MAPKK family) and the activator kinases of the MAPKK family (the MAPKKK family). The members of each respective family are structurally conserved and signals are transmitted by similar phosphotransfer reactions at corresponding steps that are mediated by a specific member of each family in turn. Both cDNAs and genes that encode putative homologues of these components have recently been isolated from plant sources. Some of them have been shown to be related not only structurally but also functionally to members of the MAPK cascades of other organisms. These findings suggest that plants have signal pathways that are analogues to the MAPK cascades in yeast and animal cells but it remains to be proven that plant homologues do in fact constitute kinase cascades.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1995

Reactive antibodies in sera from pubertal and adult gingivitis patients against various Porphyromonas gingivalis antigens.

This study was undertaken to determine the immunodominant antigens from Porphyromonas gingivalis which reacted with sera from patients of pubertal and adult gingivitis. The patients with cultivable P. gingivalis and the patients without cultivable P. gingivalis were compared by immunoblots. Fifty subjects participated in this study: 20 with gingivitis, 20 periodontally healthy, and 10 with adult periodontitis. The groups with gingivitis and healthy periodontium each contained 10 pubescent subjects and 10 adult subjects. P. gingivalis was isolated from 9 of 20 patients with gingivitis and from all of 10 with periodontitis by culture study. Approximate molecular weight 43 KDa fimbriae antigen, 57, 53, 46, 28 KDa antigens from outer membrane, and 57, 44, 40, 18.5 KDa antigens from sonicated extracts of P. gingivalis reacted significantly more frequently with sera from the P. gingivalis culture-positive gingivitis patients than with sera from the culture-negative patients by Fisher's exact test. A molecular weight 75, 31 KDa antigen from outer membrane and a 46 KDa antigen from sonicated extract were immunodominant in sera from adult patients with periodontitis. These findings indicate that the specific antigens which reacted with sera from P. gingivalis culture-positive patients are markers of infection with P. gingivalis. Additionally, reactivity to antigens were slightly different between sera from patients with gingivitis and those from patients with periodontitis.

Adhesins, Bacterial↗
PubMed1995

Effects of dose, pH and osmolarity on intranasal absorption of recombinant human erythropoietin in rats.

The effects of dose, pH and osmolarity on the intranasal absorption of a recombinant human erythropoietin (rEPO) solution were studied in male Wistar rats. The intranasal administration of rEPO was evaluated by measuring percentage circulating reticulocytes of red blood cells on a stained blood smear (smear method), and also by measuring residual circulating reticulocyte counts using a microcell counter (sysmex method). Both results suggest that rEPO solution was absorbed through the nasal mucosa of rats without enhancers after a single intranasal administration. The pharmacological availabilities of rEPO after intranasal administration compared with intravenous administration were about 7% and 4%, when estimated by smear method and sysmex method, respectively. The pharmacological activity was enhanced in low pH and hypotonic mannitol solution.

Absorption↗
PubMed1995

Identification of perhydro-1,4-thiazepine-3,5-dicarboxylic acid, cystathionine mono-oxo acids, cystathionine ketimines, cystathionine sulfoxide and N-acetylcystathionine sulfoxide in the urine sample of D,L-propargylglycine treated rats.

Novel cystathionine metabolites, perhydro-1,4-thiazepine-3,5-dicarboxylic acid (PHTZDC), cystathionine mono-oxo acids [S-(3-oxo-3-carboxy-n-propyl)cysteine and S-(2-oxo-2-carboxyethyl)homocysteine], cystathionine ketimines, cystathionine sulfoxide and N-acetylcystathionine sulfoxide were identified previously in the urine of patients with cystathioninuria. We have identified these compounds for the first time in the urine of D,L-propargylglycine-treated rats using LC/APCl-MS (liquid chromatography-mass spectrometry with an atmospheric pressure chemical ionization interface system) and an amino acid analyzer. Cystathionine mono-oxo acids and cystathionine ketimines were easily interconvertible depending on the pH of the solution. The excretion of PHTZDC, total cystathionine ketimine (cystathionine mono-oxo acids plus cystathionine ketimines), cystathionine sulfoxide and Nac-cystathionine sulfoxide in the rat urine increased in proportion to that of cystathionine content after D,L-propargylglycine administration.

Alkynes↗
PubMed1994

NPK15, a tobacco protein-serine/threonine kinase with a single hydrophobic region near the amino-terminus.

A cDNA clone (cNPK15) was isolated from tobacco cells in suspension culture, which encodes a predicted protein kinase of 422 amino acids. The predicted NPK15 protein consists of a hydrophobic region near the amino-terminus, a linker domain and the catalytic domain of a protein-serine/threonine kinase in the carboxyl-half. NPK15 was not found to be closely related to any reported protein, but its putative catalytic domain shares some structural similarity with those of receptor-like protein kinases of plants, such as ZmPK1 from Zea mays and TMK1 from Arabidopsis, even though no receptor-like domain is found in NPK15. Recombinant NPK15 expressed in Escherichia coli as a fusion protein was found capable of autophosphorylation and of phosphorylation of the histone H1 protein on both serine and threonine residues. Upon overexpression of cNPK15 under control of the promoter of cauliflower mosaic virus 35S RNA in tobacco cells, into which it had been introduced by Agrobacterium-mediated transformation, the NPK15 gene acted as a "suicide" gene and blocked proliferation of the host cells. By contrast, such a suicide effect was not observed with the gene for a kinase-negative mutant protein in which the nucleotide sequence for the ATP-binding site had been mutated or with a mutant derivative encoding a protein in which the hydrophobic region had been deleted. Thus, the protein kinase activity of NPK15 and the hydrophobic region of the protein are responsible for the suicide effect. The NPK15 protein kinase seems to be associated with specific cellular functions. Southern blot analysis with cNPK15 as the probe detected several fragments in restriction digests of genomic DNAs from both tobacco and other members of the Solanaceae. This results suggests that NPK15-related genes constitute a small gene family in the genomes of Solanaceae.

Amino Acid Sequence↗