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Biomedical subjects

T Mikami

Publications and source records attributed to T Mikami.

At least 19 recordsLinked to original sources
PubMed2006

Expression pattern of adhesion molecules in junctional epithelium differs from that in other gingival epithelia.

BACKGROUND AND OBJECTIVE: The gingival epithelium is the physiologically important interface between the bacterially colonized gingival sulcus and periodontal soft and mineralized connective tissues, requiring protection from exposure to bacteria and their products. However, of the three epithelia comprising the gingival epithelium, the junctional epithelium has much wider intercellular spaces than the sulcular epithelium and oral gingival epithelium. Hence, the aim of the present study was to characterize the cell adhesion structure in the junctional epithelium compared with the other two epithelia. MATERIAL AND METHODS: Gingival epithelia excised at therapeutic flap surgery from patients with periodontitis were examined for expression of adhesion molecules by immunofluorescence. RESULTS: In the oral gingival epithelium and sulcular epithelium, but not in the junctional epithelium, desmoglein 1 and 2 in cell-cell contact sites were more abundant in the upper than the suprabasal layers. E-cadherin, the main transmembranous molecule of adherens junctions, was present in spinous layers of the oral gingival epithelium and sulcular epithelium, but was scarce in the junctional epithelium. In contrast, desmoglein 3 and P-cadherin were present in all layers of the junctional epithelium as well as the oral gingival epithelium and sulcular epithelium. Connexin 43 was clearly localized to spinous layers of the oral gingival epithelium, sulcular epithelium and parts of the junctional epithelium. Claudin-1 and occludin were expressed in the cell membranes of a few superficial layers of the oral gingival epithelium. CONCLUSION: These findings indicated that the junctional epithelium contains only a few desmosomes, composed of only desmoglein 3; adherens junctions are probably absent because of defective E-cadherin. Thus, the anchoring junctions connecting junctional epithelium cells are lax, causing widened intercellular spaces. In contrast, the oral gingival epithelium, which has a few tight junctions, functions as a barrier.

Actins↗
PubMed2005

Molecular mapping of a fertility restorer gene for Owen cytoplasmic male sterility in sugar beet.

We report here the molecular mapping of a fertility restorer gene (named Rf1) for Owen cytoplasmic male sterility in sugar beet. Eight AFLP and two RAPD markers, tightly linked to the Rf1 locus, were identified using bulked segregant analysis. Three AFLP markers, mAFEM972, mAFEM976 and mAFEM985, were found to co-segregate with the Rf1 allele in our mapping populations. With the help of RFLP markers, previously mapped on the sugar beet genome, we showed that Rf1 is positioned in the terminal region of linkage group Kiel III/Koeln IV. This map location agrees well with that found for the restorer gene X, which suggests that the Rf1 locus corresponds to the X locus. The availability of the molecular markers will facilitate the selection of maintainer-pollinator lines in breeding program and provide the foundation for map-based cloning of the Rf1 gene.

Beta vulgaris↗
PubMed2005

Novel quantitative assessment of myocardial perfusion by harmonic power Doppler imaging during myocardial contrast echocardiography.

OBJECTIVE: To test the hypothesis that the power of the received signal of harmonic power Doppler imaging (HPDI) is proportional to the bubble concentration under conditions of constant applied acoustic pressure, and to determine whether a new quantitative method can overcome the acoustic field inhomogeneity during myocardial contrast echocardiography (MCE) and identify perfusion abnormalities caused by myocardial infarction. METHODS: The relation between Levovist concentration and contrast signal intensity (CI) of HPDI was investigated in vitro under conditions of constant acoustic pressure. MCE was performed during continuous infusion of Levovist with intermittent HPDI every sixth cardiac cycle in 11 healthy subjects and 25 patients with previous myocardial infarction. In the apical views myocardial CI (CI(myo)) was quantified in five myocardial segments. The CI from the left ventricular blood pool adjacent to the segment was also measured in dB and subtracted from the CI(myo) (relative CI (RelCI)). RESULTS: CI had a logarithmic correlation and the calculated signal power a strong linear correlation with Levovist concentration in vitro. Thus, a difference in CI of X dB indicates a microbubble concentration ratio of 10(X/10). In normal control subjects, CI(myo) differed between the five segments (p < 0.0001), with a lower CI(myo) in deeper segments. However, RelCI did not differ significantly between segments (p = 0.083). RelCI was lower (p < 0.0001) in the 39 infarct segments (mean (SD) -18.6 (2.8) dB) than in the 55 normal segments (mean (SD) -15.1 (1.6) dB). RelCI differed more than CI(myo) between groups. CONCLUSIONS: The new quantitative method described can overcome the acoustic field inhomogeneity in evaluation of myocardial perfusion during MCE. RelCI represents the ratio of myocardium to blood microbubble concentrations and may correctly reflect myocardial blood volume fraction.

Adult↗
PubMed2004

Upregulation of p16(INK4A) and Bax in p53 wild/p53-overexpressing crypts in ulcerative colitis-associated tumours.

In ulcerative colitis (UC)-associated tumours, p53 gene mutations and p53 protein overexpression are frequently found in early stages, but the two types of alteration do not always coincide. To clarify this discrepancy, p53 mutations and expression of p53-associated molecules were analysed in UC-associated dysplasias by a combination of microdissection, polymerase chain reaction-direct sequencing and immunohistochemistry at the single crypt level. Mismatch of p53 protein overexpression (+)/mutation (-) or p53 overexpression (-)/gene mutation (+) was found in nine crypts in regenerative mucosa (19 crypts), in 27 in low-grade dysplasia (41), in one in high-grade dysplasia (5) and in 12 in invasive carcinomas (17). Regarding these mismatched crypts of the first type, significant increase in p16(INK4A) and Bax expression was found. The Ki-67 labelling index was depressed in such p53-diffusely positive lesions with the wild-type p53 gene, compared to their p53-diffusely positive and mutant type counterparts. p16(INK4A) was upregulated indirectly as part of the negative feedback, and increase in Bax, directly controlled by wild-type p53, indicates upregulation of apoptosis. No significant relation with p53-related gene products was detected with the p53 protein overexpression (-)/p53 mutation (+) mismatch. Therefore, a tumorigenesis pathway independent of p53 dysfunction appears to exist in association with ulcerative colitis.

Adult↗
PubMed2004

The cytoplasmic male-sterile type and normal type mitochondrial genomes of sugar beet share the same complement of genes of known function but differ in the content of expressed ORFs.

The complete nucleotide sequence (501,020 bp) of the mitochondrial genome from cytoplasmic male-sterile (CMS) sugar beet was determined. This enabled us to compare the sequence with that previously published for the mitochondrial genome of normal, male-fertile sugar beet. The comparison revealed that the two genomes have the same complement of genes of known function. The rRNA and tRNA genes encoded in the CMS mitochondrial genome share 100% sequence identity with their respective counterparts in the normal genome. We found a total of 24 single nucleotide substitutions in 11 protein genes encoded by the CMS mitochondrial genome. However, none of these seems to be responsible for male sterility. In addition, several other ORFs were found to be actively transcribed in sugar beet mitochondria. Among these, Norf246 was observed to be present in the normal mitochondrial genome but absent from the CMS genome. However, it seems unlikely that the loss of Norf246 is causally related to the expression of CMS, because previous studies on mitochondrial translation products failed to detect the product of this ORF. Conversely, the CMS genome contains four transcribed ORFs (Satp6presequence, Scox2-2 , Sorf324 and Sorf119) which are missing from the normal genome. These ORFs, which are potential candidates for CMS genes, were shown to be generated by mitochondrial genome rearrangements.

Beta vulgaris↗
PubMed2004

Buthionine sulfoximine inhibits cytopathic effect and apoptosis induced by infection with human echovirus 9.

We studied the effect of buthionine sulfoximine (BSO) on the replication of an isolate of human echovirus 9 (EV9) and the apoptosis induced by it in GMK cells. One hundred microM BSO markedly inhibited the cytopathic effect (CPE) induced by EV9. BSO also significantly inhibited apoptosis induced by EV9. BSO did not influence replication of EV9 genome, but inhibited virion formation. These results suggest that the inhibition by BSO of CPE and apoptosis induced by EV9 may be associated with the impairment of virion formation. Moreover, apoptosis induced by infections of human poliovirus 3, human coxsackievirus B5, A10 and A16, which, like EV9, belong to the genus Enterovirus, was markedly abolished by BSO. This finding suggests that enteroviral infections cause apoptosis through the activation of a common pathway that can be inhibited by BSO.

Animals↗
PubMed2004

Effect of flow disturbances remaining at the beginning of diastole on intraventricular diastolic flow and colour M-mode Doppler echocardiograms.

A computational model of the fluid dynamics of intraventricular flow was used to investigate the importance of the effects of flow disturbances existing within the left ventricle (LV) at the onset of diastole on a diastolic flow field. The simulation started with a quiescent flow state; it continued for a number of cardiac cycles to obtain a cyclically repeatable flow. After the flow became periodic, the initial diastolic flow was not quiescent: flow disturbances, remnants of a systolic flow, were present within the LV. Nevertheless, they faded away during an acceleration phase of diastole and almost ceased by the end of this phase. Consequently, a flow field during a deceleration phase of diastole, characterised by the formation of a vortex ring, was hardly affected by the initial flow disturbances. The propagation velocity of a colour M-mode Doppler echocardiogram obtained by scanning velocity along the LV long axis was 0.58 m s(-1) in the case where diastolic flow was initially quiescent and 0.56 m s(-1) in the case where flow disturbances existed at the beginning of diastole. These results indicated that the colour M-mode Doppler echocardiographic technique captures flow dynamics produced purely by ventricular expansion, with little influence from initial diastolic flow disturbances.

Computer Simulation↗
PubMed2004

Natural IgM antibodies in sera from various animals but not the cat kill Toxoplasma gondii by activating the classical complement pathway.

Sera from swine, rabbit, and dog, that had never been exposed to Toxoplasma gondii, demonstrated significant killing of T. gondii tachyzoites in vitro, while cat serum did not. Swine and rabbit sera contained natural IgM antibody against the tachyzoites, and the classical complement pathway was activated by the binding of natural IgM antibody to the tachyzoites, leading to lysis. Anti-T. gondii antibodies, induced in swine or cat infected with T. gondii, had no killing effect by themselves but killed the tachyzoites in the presence of swine complement. However, the anti-T. gondii antibodies of swine or cat demonstrated a very low killing effect in the presence of cat complement. This suggests that T. gondii tachyzoites have an evasion mechanism to prevent lysis which is specific for cat complement.

Animals↗
PubMed2004

High microvascular density is correlated with high VEGF, iNOS and COX-2 expression in penetrating growth-type early gastric carcinomas.

AIMS: Early gastric carcinomas have two characteristic growth types, superficial spreading (SUP) and penetrating (PEN). Higher mucosal apoptotic activity and lower p21(WAF1/CIP1) expression and submucosal low proliferative activity have been shown in the former, compared with the latter. In order to cast light on whether angiogenesis contributes to these growth patterns, the present immunohistochemical study was performed with cancer tissues. METHODS AND RESULTS: Of a total of 807 early gastric carcinomas, 30 PEN and 33 SUP type submucosal invasive carcinoma cases were immunohistochemically compared. CD34 positivity, microvascular density (MVD), and expression of vascular endothelial growth factor (VEGF) and inducible nitric oxide synthase (iNOS), but not cyclooxygenase 2 (COX-2) were higher in cancer cells in both mucosal and submucosal layers in PEN than in SUP (P < 0.05). Submucosal MVD in PEN type was greater (P < 0.01) in cases with high than with low Ki67 labelling. Significant correlations were shown between MVD and VEGF, iNOS and COX-2, and VEGF and iNOS expression in the PEN type, but only a weak correlation between iNOS and COX-2 expression was evident with the SUP type. CONCLUSIONS: Increased MVD in PEN type has an intimate causal relationship to angiogenic factors, high VEGF and iNOS expression. The SUP type, in contrast, has characteristics of low angiogenesis.

Angiogenic Proteins↗
PubMed2004

Vitamin D deficiency rickets due to soybean milk.

We describe vitamin D deficiency rickets in an infant nursed with soybean milk (not specifically designed for infants) instead of cow's milk-based infant formula. Symptoms included irritability and carpopedal spasm when crying. The infant's condition improved with nutrition by vitamin-enriched cow's milk-based infant formula, oral administration 1 alpha-hydroxy vitamin D3 and exposure to sunlight. Content analysis of the milk showed very low calcium, phosphate, magnesium and vitamin D levels compared to cow's milk-based infant milk formulas. This case highlights the unsuitability of soybean milk as the sole provider of infant nutrition and demonstrates the false perception that soybean milk is a healthy food for infants. It is necessary to be cautious about not only health claims for soybean milk, but also today's health and natural food booms. Social enlightenment and correction of such misperceptions are necessary.

Humans↗
PubMed2003

Computational study on the evolution of an intraventricular vortical flow during early diastole for the interpretation of color M-mode Doppler echocardiograms.

A computational fluid dynamics study of intraventricular flow during early diastole was carried out using a 3D model of the human left ventricle (LV). It was found that a vortical flow formed under the aortic orifice and then grew in size and extended laterally along the ventricular wall towards the posterior side. With further expansion of the LV, it developed into an annular vortex asymmetrically enlarged on the side of the aortic orifice, narrowing the passage of blood inflow and thus causing a shift of the high-velocity portion of inflow towards the apex. This appeared as an elongation of the aliasing area when the velocity of the inflow was expressed as a spatiotemporal map in the same manner as a color M-mode Doppler (CMD) echocardiogram. Based on these findings, it was concluded that the shape of the aliasing area in a CMD echocardiogram shows the change in the velocity of blood inflow affected by the development of an annular vortex formed in the LV.

Blood Flow Velocity↗
PubMed2003

Phylogenetic analysis of Vietnamese isolates of feline immunodeficiency virus: genetic diversity of subtype C.

Phylogenetic relationships of novel Vietnamese strains of feline immunodeficiency virus (FIV) were analysed. One Vietnamese strain was found to cluster with subtype D, which was previously known only in Japan, while the other seven strains were placed with members of subtype C. Calculation of the relative numbers of mutations resulting in amino acid and silent changes in FIV env subtypes suggested that subtype C isolates may be less structurally constrained (potentially more pathogenic) than subtype B.

Animals↗
PubMed2002

Therapeutic effect of neuronal nitric oxide synthase inhibitor (7-nitroindazole) against MPTP neurotoxicity in mice.

Effects of neuronal nitric oxide synthase (nNOS) inhibitor (7-nitroindazole), nonselective NOS inhibitor (N(G)-nitro-L-arginine methyl ester; L-NAME), and monoamine oxidase inhibitor (pargyline) were studied on 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-treated mice. The mice received four intraperitoneal injections of MPTP at 1-h intervals. A significant depletion in dopamine and DOPAC concentration was observed in the striatum from 1 day after MPTP treatment. The pretreatment of 7-nitroindazole and pargyline, but not L-NAME, dose-dependently protected against MPTP-induced depletion in dopamine content 3 days after MPTP treatment. Our histochemical study also showed that 7-nitroindazole and pargyline can prevent a marked decrease in the nigral cells and a marked increase in astrocytes in striatum 7 days after MPTP treatment. The protective effect of 7-nitroindazole against MPTP-induced dopamine and DOPAC depletion in the striatum was not attenuated by intraperitoneal pretreatment with L-arginine. Furthermore, the posttreatment of 7-nitroindazole or pargyline protected against MPTP-induced depletion of dopamine content. These results demonstrate that the protective mechanism by which 7-nitroindazole counteracts MPTP neurotoxicity in mice may be due not only to inhibition of nNOS, but also to MAO-B inhibition. Furthermore, our study suggests that the posttreatment of 7-nitroindazole and pargyline can prevent a significant decrease in dopamine levels in the striatum of MPTP-treated mice. These findings have important implications for the therapeutic time window and choice of nNOS or MAO inhibitors in patients with Parkinson's disease.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗
PubMed2002

Development and evaluation of an enzyme-linked immunosorbent assay with recombinant SAG2 for diagnosis of Toxoplasma gondii infection in cats.

Cats are pivotal in the transmission of Toxoplasma gondii. To develop a sensitive and specific serodiagnostic method for feline toxoplasmosis, surface antigen 2 (SAG2) of T. gondii was expressed in Escherichia coli and its diagnostic potential evaluated in an enzyme-linked immunosorbent assay (ELISA). The ELISA with recombinant SAG2 (rSAG2) was able to differentiate very clearly between sera from cats experimentally infected with T. gondii and sera from normal cats. Serum samples collected from domestic cats in Japan were investigated by the ELISA, and the results were compared with those of a commercially available latex agglutination test (LAT) kit. Of the 192 samples screened, 42 (21.9%) were positive by ELISA. Among the 42 ELISA-positive samples, 39 were positive by LAT. There was a significant correlation between ELISA and LAT titers. All the 150 ELISA-negative samples were negative by LAT. These results indicate that the ELISA with rSAG2 expressed in E. coli should be a useful method for detection of T. gondii infection in cats.

Animals↗
PubMed2001

Serodiagnosis of Toxoplasma gondii infection in cats by enzyme-linked immunosorbent assay using recombinant SAG1.

The gene encoding surface antigen 1 (SAG1, P30) of Toxoplasma gondii (T. gondii) was cloned into the plasmid pGEX-4T-3 and subsequently expressed in Escherichia coli (E. coli) as a glutathione-S-transferase (GST) fusion protein. The recombinant SAG1 (rSAG1) was refolded using 8M urea solution followed by dialysis and thereafter evaluated in an enzyme-linked immunosorbent assay (ELISA) for serological diagnosis of toxoplasmosis. The test sera were adsorbed with GST to block non-specific reactivity to the GST-SAG1 fusion protein. The ELISA with rSAG1 was able to differentiate very clearly between sera from cats or mice experimentally infected with T. gondii and sera from normal cats or mice. The ELISA detected no cross-reactivity with sera from mice experimentally infected with the closely related parasite Neospora caninum (N. caninum). Some 193 cat sera were tested for antibodies to T. gondii, out of which 40 (20.7%) reacted positively by ELISA with the rSAG1 while another 79.3% cats reacted negative to the assay. Both positive and negative sera were confirmed by Western blot analysis. The results of ELISA were in agreement with those of a commercially available latex agglutination test (LAT) kit, although the former had higher titers than the latter.

Animals↗