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Biomedical subjects

M Yasuda

Publications and source records attributed to M Yasuda.

At least 73 records · Page 4Linked to original sources
PubMed2000

Phosphorylation of tau is regulated by PKN.

For the phosphorylation state of microtubule-associated protein, tau plays a pivotal role in regulating microtubule networks in neurons. Tau promotes the assembly and stabilization of microtubules. The potential for tau to bind to microtubules is down-regulated after local phosphorylation. When we investigated the effects of PKN activation on tau phosphorylation, we found that PKN triggers disruption of the microtubule array both in vitro and in vivo and predominantly phosphorylates tau in microtubule binding domains (MBDs). PKN has a catalytic domain highly homologous to protein kinase C (PKC), a kinase that phosphorylates Ser-313 (= Ser-324, the number used in this study) in MBDs. Thus, we identified the phosphorylation sites of PKN and PKC subtypes (PKC-alpha, -betaI, -betaII, -gamma, -delta, -epsilon, -zeta, and -lambda) in MBDs. PKN phosphorylates Ser-258, Ser-320, and Ser-352, although all PKC subtypes phosphorylate Ser-258, Ser-293, Ser-324, and Ser-352. There is a PKN-specific phosphorylation site, Ser-320, in MBDs. HIA3, a novel phosphorylation-dependent antibody recognizing phosphorylated tau at Ser-320, showed immunoreactivity in Chinese hamster ovary cells expressing tau and the active form of PKN, but not in Chinese hamster ovary cells expressing tau and the inactive form of PKN. The immunoreactivity for phosphorylated tau at Ser-320 increased in the presence of a phosphatase inhibitor, FK506 treatment, which means that calcineurin (protein phosphatase 2B) may be involved in dephosphorylating tau at Ser-320 site. We also noted that PKN reduces the phosphorylation recognized by the phosphorylation-dependent antibodies AT8, AT180, and AT270 in vivo. Thus PKN serves as a regulator of microtubules by specific phosphorylation of tau, which leads to disruption of tubulin assembly.

Amino Acid Sequence↗
PubMed2000

A Japanese patient with frontotemporal dementia and parkinsonism by a tau P301S mutation.

The authors report a patient carrying a missense mutation in exon 10 of tau that causes a substitution at codon 301 (P301S). Although the patient shares the rapidly progressive frontotemporal dementia of the other reported pedigrees with P301S, the clinical phenotype is unique in that parkinsonism was a major symptom in the early stage and because behavioral symptoms with dementia became prominent 2 years after the onset of the disease. This study substantiates the notion that tau mutations at codon 301 can show various phenotypes.

Adult↗
PubMed2000

Rapamycin and FK506 induce long-term potentiation by pairing stimulation via an intracellular Ca(2+) signaling mechanism in rat hippocampal CA1 neurons.

Immunophilin-CsA and -FK506 complexes bind to calcineurin (CaN) and inhibit its phosphatase activity leading to enhancement of neuronal activities. However, inhibition of CaN activity is not the mediator of modulatory activity for IP3 and ryanodine receptors and does not mediate the neurotrophic actions of FK506. FK506 binding protein (FKBP)-12 also binds rapamycin, another immunosuppressant which does not affect CaN activity. Using whole-cell patch clamp techniques, excitatory postsynaptic currents (EPSCs) were recorded and we analyzed the effect of immunosuppressants on the synaptic potentiation induced by pairing weak presynaptic stimulation with postsynaptic depolarization in CA1 neurons of rat hippocampal slices. We found that postsynaptic application of rapamycin or FK506, at low concentrations, but not cyclosporin A, in conjunction with weak pairing stimulation, induced NMDA-dependent long-term potentiation (LTP). The rapamycin-induced LTP was blocked by chelating intracellular Ca(2+) or by inhibiting the intracellular Ca(2+) release. Thus, Ca(2+) release from intracellular Ca(2+) stores is required for the induction of LTP by weak pairing stimulation in the presence of rapamycin or FK506 at postsynaptic sites. We propose that postsynaptic FKBP-12 regulates synaptic transmission by stabilizing the postsynaptic Ca(2+) signaling mechanism in rat hippocampal CA1 neurons.

Animals↗
PubMed2000

The synthetic rate of dipeptide catalyzed by organic solvent-stable protease from Pseudomonas aeruginosa PST-01 in the presence of water-soluble organic solvents.

The initial synthetic rates of peptide Cbz-Arg-Leu-NH(2) from Cbz-Arg and Leu-NH(2) using PST-01 protease in the presence and absence of organic solvents were investigated under various conditions. The synthetic rates of Cbz-Arg-Leu-NH(2) in the presence of 50% (v/v) methanol, 50% (v/v) N,N-dimethylformamide (DMF) and 60% (v/v) dimethyl sulfoxide (DMSO) were 1.6-, 2.4-, and 5.1-times higher than that in the absence of organic solvent, respectively. The PST-01 protease was not only stable in the presence of organic solvents but also exhibited high reaction rates in the presence of methanol, DMF, and DMSO. When the Cbz-Arg concentration was lower than 60mM or the Leu-NH(2) concentration was lower than 400mM, the initial rates increased lineally with increase in their concentrations. However, the rates did not increase when the Leu-NH(2) concentration was more than 500mM. The optimum temperature and pH of the reaction were 40 degrees C and 7.0, respectively.

Journal Article↗
PubMed2000

Functional identification of the apoptosis effector BH3 domain in cellular protein BNIP1.

BCL-2 family proteins play a central role in apoptosis regulation in mammals and in C. elegans. Mammalian cellular and viral anti-apoptosis proteins such as BCL-2 and E1B-19K interact with several cellular proteins. Some of these interacting proteins promote apoptosis and belong to the BCL-2 family. Certain BCL-2 family proapoptotic proteins such as BAX and BAK share extensive sequence homology with BCL-2. In contrast, certain pro-apoptotic proteins such as BIK and BID share a single death effector domain, BH3, with other BCL-2 family proteins. By mutational analysis, we show that one of the cellular proteins, BNIP1 (previously Nip-1), that interacts with BCL-2 family anti-apoptosis proteins is a 'BH3 alone' pro-apoptotic protein. Transient transfection of BNIP1 induces a moderate level of apoptosis. Deletions of the N-terminal 32 amino acid region and the C-terminal trans-membrane domain did not significantly affect pro-apoptotic activity. In contrast, deletions encompassing a region containing a motif similar to the BH3-domain abrogated the apoptotic activity. Substitution of BNIP1 BH3 domain for the corresponding sequence in BAX efficiently restored the apoptotic activity of BAX, establishing the functional identity of the BH3 domain of BNIP1. The N-terminal deletions of BNIP1 (that retain the BH3 domain) enhanced the level of interaction with BCL-XL. Mutants containing the BH3 deletions were still able to heterodimerize with BCL-XL while mutants lacking both the N-terminal region and the BH3 domain were unable to heterodimerize, suggesting that BNIP1 may bind to BCL-XL via two different binding motifs.

Amino Acid Motifs↗
PubMed2000

A novel effect of polymorphonuclear leukocytes in the facilitation of angiogenesis.

The purpose of this study was to examine whether the adhesion of polymorphonuclear leukocytes (PMNs) to endothelial cells and/or reactive oxygen species (ROS) released from PMNs are responsible for inducing angiogenesis. Angiogenesis was assessed by tube formation using endothelial cells obtained from bovine thoracic aorta (BAECs) grown on a layer of collagen type I. Addition of PMNs to BAECs weakly induced angiogenesis. The angiogenesis induced by PMNs alone was further enhanced by treatment of the PMNs with N-formyl-methionyl-leucyl-phenylalanine (FMLP), a selective activator of PMN. The involvement of PMN adhesion to BAECs via adhesion molecules in angiogenesis was investigated by using monoclonal antibodies against E-selectin and intercellular adhesion molecule-1 (ICAM-1). These antibodies blocked both the PMN adhesion to BAECs and the enhancement of angiogenesis induced by FMLP-treated PMNs. Furthermore, the enhancement of angiogenesis by FMLP-treated PMNs was blocked by catalase, a scavenging enzyme of H2O2, but not by superoxide dismutase (SOD). These results suggest that PMNs induce angiogenesis in vitro, and that the mechanism of stimulation of angiogenesis by PMNs may involve the adherence of PMNs to endothelial cells via E-selectin and ICAM-1, and H2O2, but not superoxide. Thus, activated PMNs in pathological states may not only induce tissue injury, but may also function as regulators of angiogenesis.

Animals↗
PubMed2000

The anatomic relation among the nerve roots, intervertebral foramina, and intervertebral discs of the cervical spine.

STUDY DESIGN: An anatomic study of the cervical intervertebral foramina, nerve roots, and intradural rootlets performed using a surgical microscope. OBJECTIVES: To investigate the anatomy of cervical root compression, and to obtain the anatomic findings related to cervical foraminotomy for the treatment of cervical radiculopathy. SUMMARY OF BACKGROUND DATA: Cervical foraminotomy is a procedure performed frequently for the management of cervical radiculopathy. However, anatomic studies of cervical foraminotomy have not been fully elucidated. METHODS: In this study, 18 cadavers were obtained for the study of the cervical spine. All the soft tissues were dissected from the cervical spine. Thereafter, laminectomy and facetectomy were performed on C4 through T1 using a surgical microscope. The nerve roots and surrounding anatomic structures, including intervertebral discs and foramina, were exposed. In addition, the intradural rootlets and their intersegmental connections were observed. RESULTS: The shape of the intervertebral foramina approximated a funnel, the entrance zone being the most narrow part and the root sleeves conical, with their takeoff points from the central dural sac being the largest part. Therefore, compression of the nerve roots occurred at the entrance zone of the intervertebral foramina. Anteriorly, compression of the nerve roots was caused by protruding discs and osteophytes of the uncovertebral region, whereas the superior articular process, the ligamentum flavum, and the periradicular fibrous tissues affected the nerve posteriorly. The C5 nerve roots were found to exit over the middle aspect of the intervertebral disc, whereas the C6 and C7 nerve roots were found to traverse the proximal part of the disc. The C8 nerve roots had little overlap with the C7-T1 disc in the intervertebral foramen. The C6 and C7 rootlets passed two disc levels in the dural sac. Also, a high incidence of the intradural connections between the dorsal rootlets of C5, C6, and C7 segments was found. CONCLUSIONS: This study demonstrated the anatomy of the nerve roots, rootlets, and intervertebral foramina, and may aid in understanding the pathology of cervical radiculopathy. The presence of intradural connections between dorsal nerve roots and the relation between the course of the nerve root and the intervertebral disc may explain the clinical variation of symptoms resulting from-nerve root compression in the cervical spine. To perform cervical foraminotomy for cervical radiculopathy, it is necessary to understand the detailed anatomy of the intervertebral foramina thoroughly.

Aged↗
PubMed2000

Lack of an association of estrogen receptor alpha gene polymorphisms and transcriptional activity with Alzheimer disease.

BACKGROUND: Long-term cognitive decline in postmenopausal women is associated with aging and Alzheimer disease (AD). Estrogen replacement therapy has been reported to reduce the risk of developing AD. The distribution of estrogen receptors (ERs) in neurons overlaps that of the brain neurons known to develop AD. Estrogen increases the secretion and metabolism of amyloid precursor protein, may help synapse formation, and is reported to protect neurons from toxins. Restriction fragment length polymorphisms (RFLPs) of the ERalpha gene at intron 1 and exon 2 were associated with a low bone mineral density in postmenopausal women and also with AD in a Japanese population. OBJECTIVE: To determine whether ERalpha gene polymorphisms are associated with transcriptional activity and AD. METHODS: A luciferase reporter assay analyzed enhancer activity of the ERalpha gene at intron 1 and exon 2. This activity was evaluated according to the RFLPs. The RFLPs of the ERalpha gene were determined in Japanese patients clinically diagnosed as having AD, white patients diagnosed as having AD at autopsy, and corresponding healthy control subjects. The RFLPs were also evaluated for the contribution of the ERalpha gene RFLPs to AD. RESULTS: We found weak (about 2-fold) enhancer activity of the ERalpha gene, which differed among RFLPs. Although there were racial differences in these polymorphisms, we could not confirm the previously reported association between ERalpha gene polymorphisms and AD. CONCLUSION: Regulatory element of the ERalpha gene was found in intron 1, but we found no association between ERalpha gene polymorphisms and AD.

Aged↗
PubMed2000

Pathogenesis of cleft palate in mouse embryos exposed to 2,3,7, 8-tetrachlorodibenzo-p-dioxin (TCDD).

2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) induces cleft palate in mouse embryos. It has been believed that TCDD inhibits palatal fusion by suppression of disappearance of medial edge epithelial (MEE) cells on palatal shelves. However, we found that exencephalic mouse embryos were resistant to the cleft palate-inducing action of TCDD. In the present study, we examined cell kinetics in MEE and palatal mesenchyme in embryos exposed to TCDD with or without exencephaly for elucidation of pathogenesis of cleft palate by TCDD. Pregnant Jcl:ICR mice were given TCDD orally at 40 microg/kg at gestation day (GD) 12.5. Embryos were harvested between GD 13.5 and GD 14.5 and examined for cell kinetics by bromodeoxyuridine (BrdU) and TUNEL methods. Exencephaly was induced by intraperitoneal injection of CdCl(2) at 6 mg/kg at GD 7.5. BrdU-positive cells were decreased in TCDD-treated embryos in MEE and mesenchymal cells. TUNEL-positive cells were detected in MEE both in TCDD-treated and untreated control embryos, as well as in embryos with or without exencephaly. We also measured the gap between shelves between GD 14. 0 and GD 14.5. There were no differences at GD 14.0 between control and TCDD-exposed embryos, but at GD 14.25 and GD 14.5, TCDD-exposed embryos had wider gaps than controls. These findings indicate that cleft palate by TCDD results from poor development of palatal shelves. Teratogenesis Carcinog. Mutagen. 20:73-86, 2000.

Animals↗
PubMed2000

Pathogenesis of retinoic acid-induced abnormal pad patterns on mouse volar skin.

BACKGROUND: Abnormal dermatoglyphs on human volar skin have been reported in many syndromes, but little is known about the pathogenesis. Patterns of pads on rodent limb volar skin are homologous to human dermatoglyphs. METHODS: In previous studies, we showed that transplacental exposure to teratogens induced abnormal pads in mouse fetuses. Moreover, teratogens caused abnormal pad patterns at levels below those that caused skeletal malformations. In this study, we examined morphology and cytokinetics in developing abnormal pads. Pregnant mice were treated with all-trans-retinoic acid at 20 mg/kg orally at embryonal day (E) 12.5 (vaginal plug = E0). The hindlimbs of the embryos were harvested and observed under a light microscope and by scanning electron microscopy. Cell proliferation and cell death were estimated by 5-bromo-2'-deoxyuridine (BrdU) labeling, Nile blue A vital staining, and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL). RESULTS: Retinoic acid induced aplasia of the fibular tarsal pad and supernumerary interdigital pads on hindlimbs. Cell proliferation was observed in the area of developing pad, but cell death was very rarely seen in either normal or abnormal pads. CONCLUSIONS: Retinoic acid disturbed pad patterning as a whole rather than individual pad formation.

Abnormalities, Drug-Induced↗
PubMed2000

Soybean-milk-coagulating activity of Bacillus pumilus derives from a serine proteinase.

A proteolytic enzyme from Bacillus pumilus strain TYO-67, which was able to coagulate the protein in soybean milk, was characterized enzymologically. The optimum pH and temperature for its activities were 9.0 and 50 degrees C, respectively. The enzyme was strongly believed to be a serine proteinase because it was completely inhibited by the addition of diisopropyl fluorophosphate or phenylmethanesulfonyl fluoride. Hammerstein milk casein, cytochrome c and soybean protein were good substrates for the enzyme. Seven cleavages were detected using the oxidized insulin B-chain as peptide substrate for the proteolytic specificity test of the serine proteinase from B. pumilus. The bonds most susceptible to the action of the serine proteinase from B. pumilus were Leu-15-Tyr-16. The mode of action on soybean milk protein by the enzyme from B. pumilus was also investigated. The acidic subunit in glycinin and the alpha-, alpha- and beta-subunits in beta-conglycinin were degraded during the enzyme reaction. However, the basic subunit in glycinin could not be degraded by the enzyme. The formation of coagula in soybean milk caused by the serine proteinase from B. pumilus was mainly due to the hydrophobic interaction.

Bacillus↗
PubMed2000

Development of a rapid assay for screening point mutations associated with quinolone resistance in the Pseudomonas aeruginosa parC gene.

To detect quinolone resistance-associated mutations within the Ser-80 and Glu-84 codons of the Pseudomonas aeruginosa parC gene, we developed a rapid and simple assay based on polymerase chain reaction (PCR) amplification of the region of the parC gene containing the mutation sites and digestion of the PCR products with a restriction enzyme. The mutations generating alterations at Ser-80 and Glu-84 were detected as restriction fragment length polymorphisms of the PCR products digested with HinfI. Among 22 clinical isolates tested by this assay, mutations at the Ser-80 and Glu-84 codons were detected in all 10 isolates in which the presence of the mutations had been confirmed previously by DNA sequencing. This rapid and simple assay could be a useful screening device for genetic alterations associated with resistance to quinolones in the P. aeruginosa parC gene.

4-Quinolones↗
PubMed2000

HLA-DQB1 and HLA-DPB1 genotypes in severe preeclampsia.

OBJECTIVE: To clarify whether there are susceptible HLA-DQB1 or HLA-DPB1 alleles in women with preeclampsia. METHODS: The frequency of HLA-DQB1 and HLA-DPB1 alleles was analyzed in 47 women with previous severe preeclampsia and compared with that in 85 normal fertile women. The types of HLA-DQB1 and HLA-DPB1 alleles were assessed using a polymerase chain reaction-restriction fragment length polymorphism method. RESULTS: The frequency of HLA-DQB1*04 allele in previously preeclamptic women was 21.3% (20 of 94 loci) and in the controls was 11.2% (19 of 170 loci). Thus, the HLA-DQB1*04 allele frequency was significantly higher in preeclamptic women compared with controls (P <.05 by chi(2) test, OR 2.15, 95% confidence interval 1.08, 4.27). The frequency of other HLA-DQB1 alleles and all HLA-DPB1 alleles was not significantly different between groups. The incidence of homozygosity of HLA-DQB1 or HLA-DPB1 alleles in preeclamptic women was not significantly different compared with that of normal fertile women. CONCLUSION: These data suggest that women who have the HLA-DQB1*04 allele might be susceptible to preeclampsia.

Adult↗
PubMed2000

BAG-1 expression correlates highly with the malignant potential in early lesions (T1 and T2) of oral squamous cell carcinoma.

BAG-1 is a Bcl-2-binding protein that functions as an anti-apoptotic molecule. In this report we show a possible correlation between BAG-1 expression levels and the probability of oral squamous cell carcinoma (SCC) progression. We investigated BAG-1 expression levels in 22 patients diagnosed with early lesions (T1 and T2) of oral SCCs using immunohistochemistry and western blotting. High steady-state levels of BAG-1 were detected in 13 out of 22 cases (59%). High BAG-1 expression was observed more frequently in cases with nodal metastasis (89%) than in those without nodal metastasis (38%) (P<0. 03), suggesting that BAG-1 expression levels may correlate with the pathological stage of oral SCCs. Furthermore, BAG-1 expression levels correlated with the WHO grade, i.e. 45% in grade-I cases as opposed to 72% in grade-II cases (P<0.02). These data suggest that an analysis of BAG-1 expression may be useful in establishing a prognosis for patients with oral SCCs, and especially in predicting the metastatic potential of SSCs.

Adult↗
PubMed2000

Purification and characterization of organic solvent-stable lipase from organic solvent-tolerant Pseudomonas aeruginosa LST-03.

An organic solvent-stable lipase (LST-03 lipase) secreted into the culture broth of the organic solvent-tolerant Pseudomonas aeruginosa LST-03 was purified by ion-exchange and hydrophobic interaction chromatography in the presence of 2-propanol. The purified enzyme was homogeneous as determined by SDS-PAGE. The molecular mass of the lipase was estimated to be 27.1 kDa by SDS-PAGE and 36 kDa by gel filtration. The optimum pH and temperature were 6.0 and 37 degrees C. LST-03 lipase was stable at pH 5-8 and below 40 degrees C. Its hydrolytic activity was highest against tricaproin (C6), methyl octanoate (C8), and coconut oil respectively among the triacylglycerols, fatty acid methyl esters, and natural oils investigated. The enzyme cleaved not only the 1,3-positioned ester bonds, but also the 2-positioned ester bond of triolein. It exhibited high levels of activity in the presence of n-decane, n-octane, DMSO, and DMF as well as in the absence of an organic solvent. In addition, LST-03 lipase was stabler in the presence of n-decane, ethyleneglycol, DMSO, n-octane, n-heptane, isooctane, and cyclohexane than in the absence of an organic solvent.

Journal Article↗
PubMed2000

Immunohistochemical study of type-1 blood antigen expressions in thyroid tumors: the significance for papillary carcinomas.

Immunohistochemical expressions of type 1 blood group antigens were studied for 95 cases of thyroid tumors, including 29 follicular adenomas, 23 follicular carcinomas, and 43 papillary carcinomas, applying monoclonal antibodies against DU-PAN-2, CA19-9, Lewis(a) (Le(a)), and Lewis(b) (Le(b)). Normal thyroid tissue invariably failed to express all four antigens. In follicular adenomas, DU-PAN-2 and CA19-9 were focally expressed in 7% and 21% of cases, and in follicular carcinomas, CA19-9 expression was limited to one case (4%); all cases were negative for DU-PAN-2. No or little expression of Le(a) or Le(b) was observed in these follicular tumors. In contrast, DU-PAN-2, CA19-9, Le(a), and Le(b) were expressed in 98%, 84%, 33%, and 49% of 43 papillary carcinomas, respectively. The positive stainings were observed mainly on the luminal surface of the tumor cells. The number of tumor cells that expressed DU-PAN-2 generally was greater than that of tumor cells that expressed CA19-9, Le(a), or Le(b). There was no significant difference in antigen expressions in female papillary carcinomas between subjects who were younger and older than 50 years old. The results suggest that DU-PAN-2 would be a useful immunohistochemical marker for distinguishing papillary carcinomas from follicular tumors. These immunohistochemical profiles imply the following: the activity of alpha2-3 sialyltransferase, a specific glycosyltransferase, would be more strongly enhanced in papillary carcinomas than in follicular tumors; the antigen expressions in papillary carcinomas may not be related to the alteration of the female sex hormone environment.

Adenocarcinoma, Follicular↗
PubMed2000

p53 expression in squamous dysplasia associated with carcinoma of the oesophagus: evidence for field carcinogenesis.

Squamous epithelial dysplasia is often observed multifocally in the cancerous oesophagus and is presumably considered to be a pre-cancerous lesion. A mutation of the p53 tumour suppressor gene is commonly identified in oesophageal cancer and dysplasia. p53 mutations can be anticipated immunohistochemically. In order to confirm the biological and clinical significance of p53 expressions in oesophageal field carcinogenesis, immunostaining for p53 in cancerous and multifocal precancerous lesions from resected human oesophagus was systematically investigated, while paying special attention to the contiguity of these lesions. Lesions expressing p53 were detected in 46.5% (20 of 43 lesions) of the invasive carcinoma, and in 51.0% (46 of 90 lesions) of the carcinoma in situ, and in 51.4% (92 of 179 lesions) of the dysplasia. Next, the p53 expression in dysplasia was compared with that in carcinoma for the same case. 37 of 39 (94.8%) dysplasias contiguous to p53-positive carcinomas also expressed p53 (P<0.0001). On the other hand, the isolated dysplasias without contiguity to p53-positive carcinomas, only expressed p53 protein in 44.0% (11 of 25 lesions). No significant correlations were found between the p53 staining and either the clinicopathological features or prognosis. Discordant p53 alterations, such as those seen in cancerous and isolated precancerous lesions, may thus demonstrate further evidence for a multicentric or field carcinogenesis of the human oesophagus.

Aged↗