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Biomedical subjects

T Yasuda

Publications and source records attributed to T Yasuda.

At least 271 records · Page 15Linked to original sources
PubMed1997

Aggregation of yeast cells induced by the Arg-Gly-Asp motif-containing fragment of high-molecular-mass cell-adhesion protein MFBA, derived from the basidiomycetous mushroom Lentinus edodes.

A fruiting body-specific cDNA mfbAc, derived from the basidiomycete Lentinus edodes, has been shown to encode a high-molecular-mass (2157 amino acids) cell-adhesion protein MFBA containing the Arg-Gly-Asp (RGD) motif. A 425-amino-acid fragment containing the RGD motif of MFBA (designated MFBA(582-1006) peptide) produced in Escherichia coli exhibited cell-adhesion and spreading activity toward mammalian cells and cell-aggregation activity toward basidiomycetous hyphal cells via the RGD sequence. Here we investigated the biological activity of MFBA(582-1006) peptide in Saccharomyces cerevisiae. The DNA sequence encoding MFBA(582-1006) peptide, introduced into the yeast using an expression vector, resulted in a marked aggregation of the yeast cells. The aggregation was almost completely abolished by replacement of the RGD motif by an RGE motif in the peptide sequence.

Cell Adhesion Molecules↗
PubMed1997

Bidirectional regulation of telomerase activity in a subline derived from human lung adenocarcinoma.

Telomerase is active in germline cells and tumor cells, but is either not expressed or is repressed in a majority of somatic cells. The regulation mechanism of telomerase activity has lately drawn considerable attention for the possible use of telomerase inhibitors for anti-cancer therapy. We analyzed the regulation mechanism of telomerase activity in the human lung adenocarcinoma cell line A549 and its subline A5DC7 which shows impaired tumor phenotypes. Although A549 and A5DC7 cells have similar growth potentials, when cultured in medium supplemented with 5% fetal bovine serum A5DC7 cells demonstrated a remarkable negative regulation of telomerase activity and telomere shortening. After the long-term culture, A5DC7 cells showed a large senescent cell-like morphology, arrested growth at the 106 population doubling level and entered senescence which was demonstrated by expression of the beta-galactosidase senescence marker. When the serum concentration was raised from 5% to 10% for the senescent A5DC7 cells, telomerase reactivation and telomere lengthening occurred as well as resumption of proliferation. These results demonstrate that the growth arrest seen in senescent A5DC7 cells is reversible and that telomerase activity is also bi-directionally regulated in A5DC7 cells, an event which could not be observed in normal senescent cells. This indicates that stringent telomerase repression and complete growth arrest concomitant with cellular senescence is collapsed in senescent A5DC7 cells in response to exogenous signals. Our study suggests that cellular senescence progresses and/or is regulated at multiple levels.

Adenocarcinoma↗
PubMed1997

Immunohistochemical localization of advanced glycation end products, pentosidine, and carboxymethyllysine in lipofuscin pigments of Alzheimer's disease and aged neurons.

Lipofuscins are intracellular fluorescent pigments accumulating in the central nervous system (CNS) with aging and degenerative processes such as Alzheimer's disease (AD). Although they are thought to be lipid peroxidation products derived from malondialdehyde, their biogenesis remains controversial. We further characterize the chemical nature of lipofuscins in brain tissues from AD patients and normal aged subjects. Advanced glycation end products (AGEs), pentosidine and carboxymethyllysine (CML), were identified by appropriate specific antibodies. They have physicochemical properties similar to those of lipofuscin and also increase with aging. Pentosidine and CML were identified in the neuronal perikarya and the extraneuroperikaryal deposits of both the AD and aged brain. Pentosidine, but not CML, was present in the fiber-like structure within the neuropil and the core of classical senile plaque. In the brain of young subjects without CNS disease, pentosidine and CML staining was faint. Pentosidine and CML co-localized with lipofuscin pigments in the neuronal perikarya of both the AD and aged brain. We demonstrate for the first time that lipofuscin is constituted not only of lipid peroxidation products but also from glycation products which may be the origin of fluorescent pigments. Lipofuscins should thus be considered as fluorescent pigments generated by lipid- and sugar-derived Schiff base-protein polymers.

Adolescent↗
PubMed1997

Rabbit DNase I: purification from urine, immunological and proteochemical characterization, nucleotide sequence, expression in tissues, relationships with other mammalian DNases I and phylogenetic analysis.

DNase I from rabbit urine was purified approx. 3600-fold to apparent homogeneity with a 41% yield by affinity chromatography utilizing DNA-cellulose; the purity of the final preparation was assessed by SDS/PAGE, lack of contamination by other nucleases and production of a monospecific antibody against the enzyme. Although the proteochemical and enzymological properties of the purified enzyme resembled those of other mammalian DNases I, the enzymic activity of rabbit DNase I was less efficiently inhibited by monomeric actin than was that of human DNase I, probably due to substitution of an amino acid residue involved in actin binding (Tyr-65 to Phe). The effects of specific antibodies to human, rabbit and rat DNases I on the activities of the corresponding purified enzymes revealed that human DNase I lies between the rat and rabbit enzymes with regard to its immunological properties. An 1158 bp full-length cDNA encoding rabbit DNase I was constructed from the total RNA of rabbit pancreas using a combination of reverse transcriptase-PCR and rapid amplification of cDNA ends, followed by sequencing. This identified a 17- or 21-amino-acid signal sequence, with the mature enzyme containing 260 amino acids and a single N-glycosylation site at Asn-18. The amino acid sequence deduced from the cDNA sequence exactly matched that determined proteochemically from the purified enzyme up to residue 20. A systematic survey of DNase I distribution as measured by both enzymic activity and DNase I gene transcripts in 12 rabbit tissues showed the pancreas and parotid gland to produce equivalent levels, higher than those in other tissues. Enzymic activity and DNase I gene expression levels in each tissue correlated well. The results of phylogenetic and sequence identity analysis, immunological properties and tissue-distribution patterns of DNase I indicated a closer relationship between the rabbit and human enzymes than for other mammalian DNases I. Furthermore, differences between the enzymic activities expressed in mammalian parotid gland and pancreas suggest that the distribution of DNase I in mammalian tissue is species-specific.

Amino Acid Sequence↗
PubMed1997

Ultrasonographic evaluation of tumorous lesions in digital vessels.

Ultrasonography has recently been used for evaluation of various conditions in Orthopaedics. Ultrasonographic examination is a noninvasive screening test especially for soft tissue masses. Ultrasonography is also a useful and essential diagnostic tool in cardiovascular disorders because real-time images of heart and vessels can be obtained. However, there have been few reports which describe ultrasonographic evaluation of tumorous lesions in digital vessels. In this paper, such lesions in two cases were evaluated by ultrasonography. An aneurysm of the digital artery is one of the definite candidates for ultrasonographic evaluation.

Adolescent↗
PubMed1997

Geranylgeranylated rho small GTPase(s) are essential for the degradation of p27Kip1 and facilitate the progression from G1 to S phase in growth-stimulated rat FRTL-5 cells.

Cyclin-dependent kinase (Cdk) enzymes are activated for entry into the S phase of the cell cycle. Elimination of Cdk inhibitor protein p27Kip1 during the G1 to S phase is required for the activation process. An inhibitor of 3-hydroxy-3-methylglutaryl-CoA reductase prevents its elimination and leads to G1 arrest. Mevalonate and its metabolite, geranylgeranyl pyrophosphate, but not farnesyl pyrophosphate, restore the inhibitory effect of pravastatin on the degradation of p27 and allow Cdk2 activation. By the addition of geranylgeranyl pyrophosphate, Rho small GTPase(s) are geranylgeranylated and translocated to membranes during G1/S progression. The restoring effect of geranylgeranyl pyrophosphate is abolished with botulinum C3 exoenzyme, which specifically inactivates Rho. These results indicate (i) among mevalonate metabolites, geranylgeranyl pyrophosphate is absolutely required for the elimination of p27 followed by Cdk2 activation; (ii) geranylgeranylated Rho small GTPase(s) promote the degradation of p27 during G1/S transition in FRTL-5 cells.

Animals↗
PubMed1997

Localization of plasminogen activators and their inhibitor in squamous cell carcinomas of the head and neck.

BACKGROUND: Plasminogen activators (PAs) and their inhibitors are thought to play an important role in tumor invasion and metastasis. However, there have been few reports in which histologic localization of PAs has been demonstrated in head and neck tumors. METHODS: We examined the patterns of expression of urokinase-type plasminogen activator (u-PA), tissue-type plasminogen activator (t-PA), plasminogen activator inhibitor 1 (PAI-1), and vitronectin in head and neck squamous cell carcinomas using immunohistochemical techniques. We also studied the correlation between the immunohistologic expression of these fibrinolytic proteins and the clinical staging of the tumor. RESULTS: Of 28 tumor specimens, 15 (54%) showed immunoreactivity for u-PA; 8 (36%), for t-PA; and 23 ( 82%), for PAI-1. There was a significant correlation between PAI-1 expression and the extent of the primary tumor. CONCLUSIONS: The present study demonstrates the existence and possible pathophysiologic significance of u-PA and PAI-1 in squamous cell carcinomas of the head and neck.

Carcinoma, Squamous Cell↗
PubMed1997

The fifth allele of the human deoxyribonuclease I (DNase I) polymorphism.

The fifth allele, DNASE1*5, of human deoxyribonuclease I (DNase I) has been discovered. Polymerase chain reaction fragments containing exon 5 of the DNase I gene were screened for DNA polymorphism using single-strand conformation polymorphism (SSCP) analysis. DNAs from 114 unrelated Japanese and 81 German individuals were tested and a new variant was detected. By DNA sequencing analysis, this variant was found to be caused by a heterozygous G-A transition at nucleotide position 1227 that results in a Val to Met substitution at amino acid position 92 of the mature enzyme. The nucleotide substitution was also confirmed by mismatched polymerase chain reaction (PCR)-restriction fragment length polymorphism (RFLP) analysis. Genotyping of the variant could be carried out by three independent reactions based on PCR amplification, and phenotyping by isoelectric focusing followed by immunostaining. The results supported the presence of the fifth codominant allele, DNASE1*5, which generates a new isozyme.

Alleles↗
PubMed1997

Locations of crossover breakpoints within the CMT1A-REP repeat in Japanese patients with CMT1A and HNPP.

The crossover breakpoints for Charcot-Marie-Tooth disease type 1A (CMT1A) and hereditary neuropathy with liability to pressure palsies (HNPP) are located in the CMT1A-REP repeat flanking a 1.5-Mb region of chromosome 17p11.2-12. The precise locations of the breakpoints are heterogeneous, and we analyzed the relative frequency distribution of breakpoints in 33 unrelated Japanese CMT1A and 3 unrelated HNPP families. The CMT1A-REP repeat region was divided into five regions, A, B, C, D and E, based on restriction site differences between the proximal and distal CMT1A-REP repeats. The frequency distribution of breakpoints within the CMT1A-REP repeat in the Japanese patients was 3% in region A, .78% in B/C and 19% in D, which is similar to that in Caucasian patients. This result also indicates that an 8-kb region defined by region B/C is a recombinational hotspot within the CMT1A-REP repeat in Japanese patients.

Asian People↗
PubMed1997

Dramatic response of postthymomectomy myasthenia gravis with multiple lung nodules to corticosteroids.

A 36-year-old woman underwent thymomectomy and left pneumonectomy with total pleurectomy for stage IVa invasive thymoma without myasthenia gravis. Six years later, a crisis of myasthenia gravis developed associated with multiple lung nodules. Steroid therapy induced remarkable regression of the lung nodules that has persisted for more than 11 months. Concurrently, the clinical severity of her myasthenia gravis markedly decreased and recovered to the extent of permitting her to return to normal life.

Adult↗
PubMed1997

Periodic lateralized epileptiform discharges in mitochondrial encephalomyopathy.

Periodic lateralized epileptiform discharges (PLEDs) were transiently recorded during the acute phase of cerebral stroke-like episodes in three patients with mitochondrial encephalomyopathy (MEM). One of the patients developed stroke-like episodes three times, always accompanied by PLEDs. These discharges were recorded from the hemisphere responsible for the stroke-like episodes or from the more severely affected hemisphere when bilateral hemispheres were affected. Although PLEDs have been rarely reported in MEM, this disease should be considered as a differential diagnosis of cerebral infarction with PLEDs.

Adult↗
PubMed1997

A monoclonal antibody that recognizes ganglioside GD1b in the rat central nervous system.

A monoclonal antibody (MAb), generated by immunizing BALB/c mice with homogenized bovine retinal tissue, was specific to ganglioside GD1b incorporated into liposome membranes. The antibody (MAb-5G6), classified as IgM, immunostained intensely the perikaryon and processes of motoneurons in the cranial motor nuclei and spinal cord. Spinal and trigeminal ganglion cells were also immunopositive to the MAb. Some fiber tract systems, such as the spinal and mesencephalic trigeminal tracts, the solitary tract and the posterior funiculus, were also immunoreactive to the MAb. These findings suggest that MAb-5G6 labeled specifically neurons with axons extending outside of the central nervous system as a peripheral nerve. The immunoreactive substances were visualized under electron microscopy just beneath the postsynaptic membrane and just inside the plasmalemma of the thick dendrites. No axon terminal was immunolabeled by the MAb. In the rat embryos, immunoreactivity to MAb-5G6 was found in the dorsal and ventral root fibers on the 15th embryonic day (E15). However, cell bodies of the spinal ganglion cells and motoneurons were immunostained by MAb-5G6 at a later stage (E20). The ventral commissure fibers in the floor plate of the spinal cord were transiently immunolabeled during E13-15.

Animals↗
PubMed1997

Near-infrared monitoring of myocardial oxygenation during intermittent warm blood cardioplegia.

OBJECTIVE: This study was performed to examine the ability of near-infrared spectroscopy to monitor tissue oxygenation in the cardioplegically arrested heart and to assess myocardial oxygen metabolism during intermittent warm blood cardioplegia. METHODS: Using a three-wavelength near-infrared spectroscopy, we continuously measured myocardial tissue oxygen saturation and the tissue hemoglobin concentration during intermittent warm blood cardioplegia. Under normothermic cardiopulmonary bypass, 20 dogs received three 5-min periods of antegrade warm blood cardioplegia, interrupted by three 10-min episodes of ischemia in group 1 (n = 7), three 15-min episodes of ischemia in group 2 (n = 6), or three 20-min episodes of ischemia in group 3 (n = 7). RESULTS: Myocardial oxygen saturation during beating and ventricular fibrillation was 80 +/- 1 and 59 +/- 1%, respectively. Myocardial oxygen saturation rapidly increased to 82 +/- 1% at blood cardioplegic infusion and decreased to 58 +/- 1% 3 min after cardioplegic interruption. The time required to reach the peak oxygen saturation level decreased significantly at the second and third infusions compared to the first infusion in group 1, whereas the time increased significantly at the third infusion in groups 2 and 3. The slower rate of increase in oxygen saturation suggested reduced coronary vasodilator reserve due to microvascular abnormalities. Reperfusion ventricular fibrillation occurred in none of group 1, one of group 2 and three of group 3. CONCLUSIONS: Near-infrared spectroscopy is a useful method of continuously monitoring myocardial oxygenation and ischemia during warm heart surgery. Episodes of ischemia longer than 10 min during warm blood cardioplegia resulted in less-than-optimal myocardial preservation and should be avoided.

Analysis of Variance↗
PubMed1997

Mouse deoxyribonuclease I (DNase I): biochemical and immunological characterization, cDNA structure and tissue distribution.

Mouse urinary deoxyribonuclease I (DNase I) resembles rat and human DNase Is in terms of its proteochemical and enzymological properties. Furthermore, mouse DNase I was demonstrated to be immunologically closer to the rat than to the human enzyme. A 1176 bp full length cDNA encoding mouse DNase I was constructed from RNA obtained from the kidney and parotid glands. The amino acid sequence up to the 45th residue from the N-terminal of the mature enzyme was identical to that deduced from the cDNA sequence. This DNase I was distributed most densely in the parotid glands from the standpoint of both enzyme activity and gene transcript levels.

Amino Acid Sequence↗