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Biomedical subjects

N Yamasaki

Publications and source records attributed to N Yamasaki.

At least 19 recordsLinked to original sources
PubMed2006

[Surgical treatment for stage IV lung cancer].

OBJECTIVE: To find out the optimal surgical indication in stage IV lung cancer patients, we evaluated them retrospectively. METHODS & RESULTS: From 1975 to 2005, 62 patients without multiple metastases were operated at our hospital. The most common histological type was adenocarcinoma (67.7%). The metastatic lesions were lung (33.9%), brain (24.2%), liver, bone, adrenal gland and so on. The overall survival rate of stage IV lung cancer was 10.4% at 5-year. Five-year survival for patients with lung or brain metastasis who had no lymph node metastasis were significantly more superior than those with lymph node metastasis (p=0.0389, 0.0021). Four of 62 patients had 5-year survival. Two were lung and the others were brain and adrenal gland metastasis without lymph node metastasis. CONCLUSION: Stage IV lung cancer with lung or brain or adrenal gland metastasis without lymph node metastasis should be resected.

Adenocarcinoma↗
PubMed2001

Cardiac-specific overexpression of cyclin-dependent kinase 2 increases smaller mononuclear cardiomyocytes.

Cyclin-dependent kinase 2 (cdk2) plays a critical role in the G1- to S-phase checkpoint of the cell cycle. Adult cardiomyocytes are believed to withdraw from the cell cycle. To determine whether forced overexpression of cdk2 results in altered cell-cycle regulation in the adult heart, we generated transgenic mice specifically overexpressing cdk2 in hearts. Transgenic hearts expressed high levels of both cdk2 mRNA and catalytically active cdk2 proteins. Cdk2 overexpression significantly increased the levels of cdk4 and cyclins A, D3, and E. There was an increase in both DNA synthesis and proliferating cell nuclear antigen levels in the adult transgenic hearts. The ratio of heart weight to body weight in cdk2 transgenic mice was significantly increased in neonatal day 2 but not in adults compared with that of wild-type mice. Analysis of dispersed individual adult cardiomyocytes showed a 5.6-fold increase in the proportion of smaller mononuclear cardiomyocytes in the transgenic mice. Echocardiography revealed that transgenic heart was functionally normal. However, adult transgenic ventricles expressed beta-myosin heavy chain and atrial natriuretic factor. Surgically induced pressure overload caused an exaggerated maladaptive hypertrophic response in transgenic mice but did not change the proportion of mononuclear cardiomyocytes. The data suggest that overexpression of cdk2 promotes smaller, less-differentiated mononuclear cardiomyocytes in adult hearts that respond in an exaggerated manner to pressure overload.

Animals↗
PubMed2001

Nkx2.5 and Nkx2.6, homologs of Drosophila tinman, are required for development of the pharynx.

Nkx2.5 and Nkx2.6 are murine homologs of Drosophila tinman. Their genes are expressed in the ventral region of the pharynx at early stages of embryogenesis. However, no abnormalities in the pharynges of embryos with mutations in either Nkx2.5 or Nkx2.6 have been reported. To examine the function of Nkx2.5 and Nkx2.6 in the formation of the pharynx, we generated and analyzed Nkx2.5 and Nkx2.6 double-mutant mice. Interestingly, in the double-mutant embryos, the pharynx did not form properly. Pharyngeal endodermal cells were largely missing, and the mutant pharynx was markedly dilated. Moreover, we observed enhanced apoptosis and reduced proliferation in pharyngeal endodermal cells of the double-mutant embryos. These results demonstrated a critical role of the NK-2 homeobox genes in the differentiation, proliferation, and survival of pharyngeal endodermal cells. Furthermore, the development of the atrium was less advanced in the double-mutant embryos, indicating that these two genes are essential for both pharyngeal and cardiac development.

Animals↗
PubMed2001

Calcium ions stabilize a protein structure of hemolytic lectin CEL-III from marine invertebrate Cucumaria echinata.

CEL-III, a galactose/N-acetylgalactosamine (Gal/GalNAc)-specific lectin purified from a marine invertebrate, Cucumaria echinata, has a strong hemolytic activity, especially toward human and rabbit erythrocytes in the presence of Ca2+. We evaluated the role of Ca2+ in hemagglutinating and hemolytic activities of CEL-III. We found that Ca2+ is closely associated with both activities of CEL-III. The fluorescence spectra of CEL-III upon binding to Ca2+ were measured. The result showed a structural change of CEL-III in the presence of Ca2+. The structural change of CEL-III upon Ca2+ binding was further demonstrated by stabilization against urea denaturation and by insusceptibility to protease digestions. CEL-III was completely unfolded at a low concentration of 2 M urea, while CEL-III complexed with Ca2+ was stable in 6 M urea. As for protease digestions, CEL-III monomer and oligomer were readily digested by trypsin, chymotrypsin, and papain in the absence of Ca2+, while they were insusceptible to the three proteases in the presence of Ca2+. The papain digestion of the decalcified oligomer produced a large C-terminal peptide, suggestting that the C-terminal region of CEL-III may participate in oligomerization of CEL-III as a core domain.

Animals↗
PubMed2001

Molecular cloning and functional expression of cDNA encoding the cysteine proteinase inhibitor Sca from sunflower seeds.

Sunflower cystatin a (Sca) is distinguished from other phytocystatins by its lack of the N-terminal about 20 amino acids, resulting in the absence of the evolutionarily conserved Gly residue. The cDNA encoding Sca was amplified by PCR methods. The cDNA consists of 520 nucleotides and includes an open reading frame encoding a polypeptide of 98 amino acids. Comparison of the deduced amino acid sequence with the Sca protein sequence indicated that the deduced sequence has an extra 15 amino acids and one amino acid at the N- and C-termini, respectively. This result suggests that Sca is synthesized as a preprotein (preSca) and proteolytic cleavages at peptide bonds may give rise to the mature Sca. To address this assumption and also to investigate the significance of the N-terminal extension sequence to Sca for inhibitory activity, a recombinant pre-Sca (rpre-Sca), in which the N-terminal extension was fused to the matured Sca, and a recombinant matured Sca (rSca) were overproduced in Escherichia coli cells. Incubation of the rpre-Sca with a seed extract resulted in a mobility by SDS-PAGE that was the same as rSca, demonstrating a proteolytic cleavage by endogenous proteinases. The rSca and rpre-Sca proteins were further characterized with respect to inhibitory activity and sensorgrams of the interaction with papain. The result showed that rpre-Sca had stronger inhibitory activity than rSca, and that the increased activity toward papain was due to a lower dissociation rate constant. This finding indicates that the N-terminal region of rpre-Sca increases the inhibitory activity by stabilizing the rpre-Sca and papain complex.

Amino Acid Sequence↗
PubMed2000

Crystal structures of the ribonuclease MC1 from bitter gourd seeds, complexed with 2'-UMP or 3'-UMP, reveal structural basis for uridine specificity.

Ribonuclease MC1 (RNase MC1) isolated from seeds of bitter gourd (Momordica charantia) consists of 190 amino acids and is characterized by a preferential cleavage at the 5'-side of uridine. This uridine specificity distinguishes RNase MC1 from other enzymes belonging to the RNase T2 family. The three-dimensional structures of RNase MC1, in a complex with either 2'-UMP or 3'-UMP, were determined at 1.48 and 1.77 A resolutions, respectively. The side chains of Gln9 and Asn71 interact with O4 and N3, respectively, of the uracil base by hydrogen bondings. In addition, the uracil base is sandwiched by the hydrophobic side chains of Leu73 and Phe80. Compared with these amino acid residues and corresponding residues in RNases in the RNase T2 family, Gln9 and Phe80 are highly conserved in the RNases in T2 family, while Asn71 and Leu73 in RNase MC1 are variant in sequences. It is thus likely that interactions of the side chains of Asn71 and Leu73 with the uracil base are responsible for the absolute uridine specificity of RNase MC1. Site-directed mutagenesis experiments showed that replacement of Asn by Thr decreased both the catalytic efficiency and the binding affinity by 2.3- and 7.0-fold, respectively, and substitution of Leu73 for Ala predominantly decreased the binding affinity by 14. 5-fold, compared with findings in case of wild-type RNase MC1. It is thus demonstrated that Asn71 and Leu73 play an essential role in uridine preference for RNase MC1.

Amino Acid Sequence↗
PubMed2000

Biological activities of the lectin, abrin-a, against human lymphocytes and cultured leukemic cell lines.

The cytoagglutination by abrin-a against human cultured cell lines derived from acute lymphoblastic leukemia (ALL) and human peripheral blood lymphocytes obtained from normal adults and from patients with adult T cell leukemia (ATL) was investigated. Among acute T lymphoblastic leukemia (T-ALL) cell lines, abrin-a showed strong cytoagglutination against relatively differentiated cell lines, such as Jurkat and CCRF-HSB-2. Among acute B lymphoblastic leukemia (B-ALL) cell lines, abrin-a strongly agglutinated an immature cell line, NALM6. In comparison with ALL cell lines, cytoagglutination by abrin-a against normal lymphocytes was weak. Abrin-a showed higher cytoagglutination against lymphocytes derived from ATL than lymphocytes derived from normal adults. In connection with the cytoagglutination, abrin-a-induced cytotoxicity against human cultured leukemic cell lines was evaluated. In proportion to the extent of cytoagglutination, abrin-a induced cytotoxicity in Jurkat, CCRF-HSB-2, MOLT-4, RPMI8402, and BALL-1 as well. Although CCRF-CEM and BALM-1 were both weakly agglutinated by abrin-a, these cell lines were very sensitive to the abrin-a-induced cytotoxicity. NALM6 was strongly agglutinated by abrin-a, but abrin-a exhibited less strong cytotoxicity against this cell line. These results suggest the feasible application of abrin-a as a tool to distinguish the human leukemic cells and its potential for clinical application.

Abrin↗
PubMed2000

Interaction of the hemolytic lectin, CEL-III, with cultured human leukemic cell lines.

We studied interaction of CEL-III with cultured human leukemic cell lines and lymphocytes from normal adults by evaluating the extent of cytotoxicity and cytoagglutination. Among acute T lymphoblastic leukemia (T-ALL) cell lines, CEL-III displayed increased toxicity against different acute lymphoblastic leukemia (ALL) cell lines as a function of increasing differentiation stage. In the case of acute B lymphoblastic leukemia (B-ALL) cell lines, CEL-III showed strong cytotoxicity against relatively immature cell lines. We found that CEL-III was more toxic for ALL cell lines than leukocytes obtained from peripheral blood of healthy adults. Strong influence of the additional amount of calcium ion on the extent of cytotoxicity was observed. In addition, we describe a new way to evaluate the extent of cytoagglutination in "% of agglutinated cells". These findings make CEL-III a promising candidate in research for lectins which bind to and destroy only the targeted leukemic cells.

Adult↗
PubMed2000

Molecular cloning and functional expression of cDNA encoding the cysteine proteinase inhibitor with three cystatin domains from sunflower seeds.

Two cysteine proteinase inhibitors, cystatins Sca and Scb, were previously isolated from sunflower seeds [Kouzuma et al. J. Biochem. 119 (1996) 1106-1113]. A cDNA clone encoding a novel phytocystatin with three repetitive cystatin domains was isolated from a cDNA library of sunflower seeds using the Sca cDNA fragment as a hybridization probe. The cDNA insert comprises 1,093 bp and encodes 282 amino acid residues. The deduced amino acid sequences of the domains are highly similar to each other (66-81%), sharing 65-90% identical residues with Sca. The cDNA was expressed in Escherichia coli cells, and then the recombinant sunflower multicystatin (SMC) was purified and its inhibitory activity toward papain was examined. SMC exhibited strong inhibitory activity toward papain, with a stoichiometry of 1:3, indicating that each cystatin domain independently functions as a potent cysteine proteinase inhibitor. Proteolysis of SMC with Asn-specific proteinase suggested that post-translational processing by an Asn-specific proteinase may give rise to mature Sca-like phytocystatins.

Amino Acid Sequence↗
PubMed2000

Phenotypic characterization of the murine Nkx2.6 homeobox gene by gene targeting.

The NK-2 homeobox genes have been shown to play critical roles in the development of specific organs and tissues. Nkx2.6 is a member of the NK-2 homeobox gene family and is most closely related to the Drosophila tinman gene. Nkx2.6 is expressed in the caudal pharyngeal pouches, the caudal heart progenitors, the sinus venosus, and the outflow tract of the heart and in a short segment of the gut at early stages of embryogenesis. To investigate the function of Nkx2.6 in vivo, we generated mice with null mutations of Nkx2.6 by the gene targeting technique. Homozygous Nkx2.6 mutant mice were viable and fertile. There were no obvious abnormalities in the caudal pharyngeal pouch derivatives (the thymus, parathyroid glands, and thyroid gland), heart, and gut. Expression of Nkx2.6 overlaps that of Nkx2.5 in the pharynx and heart and that of Nkx2.3 in the pharynx. Interestingly, in mutant embryos homozygous for Nkx2.6, Nkx2.5 expression extended to the lateral side of the pharynx, suggesting a compensatory function of Nkx2.5 in the mutant pharyngeal pouches.

Animals↗
PubMed2000

Expression and mutational analysis of amino acid residues involved in catalytic activity in a ribonuclease MC1 from the seeds of bitter gourd.

The ribonuclease MC1 (RNase MC1) from seeds of bitter gourd (Momordica charantia) consists of 190 amino acids and belongs to the RNase T2 family, including fungal RNases typified by RNase Rh from Rhizopus niveus. We expressed RNase MC1 in Escherichia coli cells and made use of site-directed mutagenesis to identify essential amino acid residues for catalytic activity. Mutations of His34 and His88 to Ala completely abolished the enzymatic activity, and considerable decreases in the enzymatic activity were observed in cases of mutations of His83, Glu84, and Lys87, when yeast RNA was used as a substrate. Kinetic parameters for the enzymatic activity of the mutants of His83, Glu84, and Lys87 were analyzed using a dinucleoside monophosphate CpU. Km values for the mutants were approximately like that for wild-type, while k(cat) values were decreased by about 6 to 25-fold. These results suggest that His34, His83, Glu84, Lys87, and His88 in RNase MC1 may be involved in the catalytic function. These observation suggests that RNase MC1 from a plant catalyzes RNA degradation in a similar manner to that of fungal RNases.

Amino Acids↗
PubMed2000

Some properties of a macromolecular conjugate of lysozyme prepared by modification with a monomethoxypolyethylene glycol derivative.

Hen egg-white lysozyme was modified with a succinyl ester derivative of monomethoxypolyethylene glycol (mPEG-COONSu), and some properties of the resulting conjugate (mPEG-lysozyme) were studied. The conjugate was prepared by modification of lysozyme with mPEG-COONSu and purified with use of columns of CM-Toyopearl 650M and Sephadex G-75. Analytical data indicated that in the conjugate, 1.05 moles of mPEG with an average molecular weight of 5,000 were covalently attached to the lysozyme molecule. Tryptic peptide analysis of the conjugate showed that Lys 33 in lysozyme is the residue mainly modified with mPEG-COONSu. Covalent attachment of the mPEG-derivative to amino groups greatly increased the thermostability of lysozyme without any conformational change of the protein molecule. mPEG-lysozyme retained full enzyme activity for glycol chitin, but lytic activity for Micrococcus luteus cells in neutral media was 75% of that of native lysozyme and its optimal pH was at pH 5.0. It was also found that the reactivity of lysozyme with anti-lysozyme antibody from BALB/c mice or human lymphocytes was decreased by modification with mPEG-COONSu. From these findings, it was suggested that mPEG-COONSu can be advantageously used for protein tailoring of lysozyme.

Animals↗
PubMed2000

[Thoracoscopic resection for benign solitary fibrous tumor of the parietal pleura].

We have experienced thoracoscopic surgery for benign solitary fibrous tumor of the parietal pleura. A 46-year-old woman was admitted to our hospital because of chest abnormal shadow. Under thoracoscopy the tumor that was connected to the parietal pleura with a wide pedicle was completely resected with combined parietal resection of the pleura. Pathological diagnosis was a benign solitary fibrous tumor developed from the connective tissues under the parietal pleura. Thoracoscopic surgery is well indicated for a solitary fibrous tumor and wide excision of the tumor with combined resection of the pleura is important to prevent a local recurrence.

Female↗
PubMed1999

Primary structure of hemolytic lectin CEL-III from marine invertebrate Cucumaria echinata and its cDNA: structural similarity to the B-chain from plant lectin, ricin.

CEL-III, a galactose/N-acetylgalactosamine (Gal/GalNAc) specific lectin purified from a marine invertebrate Cucumaria echinata has a strong hemolytic activity especially toward human and rabbit erythrocytes. We determined the primary structure of the CEL-III by examining the amino acid sequences of the protein and the nucleotide sequence of the cDNA. The cDNA encoding CEL-III has 1823 nucleotides and an open reading frame of 1296 nucleotides. CEL-III is composed of 432 amino acid residues with a M(r) of 47¿ omitted¿457 and has six internal tandem repeats, each with of 40-50 amino acids, comprising the N-terminal two-thirds of the molecule. Similar repeats are found in the B-chains of cytotoxic plant lectins, such as ricin and abrin, where six repetitive sequences extend throughout the molecules. A hydropathy plot predicts hydrophobic segments in the C-terminal region of CEL-III. These findings suggest that the N-terminal region of CEL-III plays an important role in binding to carbohydrate receptors on the target cell membranes, an event which triggers an intermolecular hydrophobic interaction of the C-terminal region, the result being oligomerization of CEL-III to lead to pore-formation in erythrocyte membrane.

Abrin↗
PubMed1999

Factors that predict intrahepatic recurrence of hepatocellular carcinoma in 81 patients initially treated by percutaneous ethanol injection.

BACKGROUND: In Japan, where liver transplantation has not been used to treat patients with hepatocellular carcinoma (HCC), percutaneous ethanol injection (PEI) has been employed for those with small HCCs that are not amenable to surgical resection. In the current study, the authors evaluated PEI as a treatment for HCC patients by studying recurrence rates and survival after treatment. They then examined the clinicopathologic factors that predicted patterns of local and distant intrahepatic recurrence. METHODS: For 81 patients who underwent PEI as initial therapy between 1990 and 1997, the cumulative recurrence and survival rates and their correlations with 16 clinicopathologic factors were studied using the Kaplan-Meier method. RESULTS: The 3-year overall cumulative rates of intrahepatic recurrence and survival were 81% and 84%, respectively. At the end of the observation period, intrahepatic recurrence was detected in 56 patients (69%). In 21 (38%) of 56 patients, local recurrences were significantly associated with earlier stages of underlying cirrhosis, decreased indocyanine green retention at 15 minutes (ICG R15), larger tumor size, and histologically advanced tumor grade. Distant intrahepatic recurrence was also significantly associated with liver function and ICG R15. CONCLUSIONS: PEI is most effective as the initial treatment for patients with well-differentiated HCC when the tumor is less than 15 mm in greatest dimension. However, local recurrence depends predominantly on the biologic characteristics of the tumor, regardless of the efficacy of PEI. Surgical resection of HCC should be considered, especially for patients with mild liver dysfunction.

Aged↗
PubMed1999

Twenty-four-hour preservation in gamma-hydroxybutyrate improves lung function in a canine single-lung allotransplantation.

BACKGROUND: We investigated the effect of gamma-hydroxybutyrate (GHB) when added to the low-potassium University of Wisconsin (LPUW) solution used for the preservation of canine lung for 24 hr. We also examined the effect of pretreatment of donor and recipient dogs with GHB on lung function after transplantation. METHODS: Two groups were investigated. In the LPUW group, donor lungs were flushed with LPUW solution without GHB. In the GHB group, donor and recipient dogs were pretreated with GHB, and donor lungs were flushed with LPUW containing GHB. RESULTS: Posttransplant graft function was best in the GHB group. At 1 hr after reperfusion, PaO2 in the GHB group (475.7+/-96.2 mmHg) was significantly higher than in the LPUW group (188.3+/-102.7 mmHg, P<0.05). Furthermore, the use of GHB resulted in a significant increase in lung compliance (28.3+/-6.5 ml/cm H2O) compared with LPUW group (21.5+/-2.8 ml/cm H2O). CONCLUSIONS: Our results suggest that GHB is potentially useful for functional improvement of hypothermically preserved canine lung allografts after reperfusion.

Adenosine↗
PubMed1999

Expression of a recombinant porcine zona pellucida glycoprotein ZP1 in mammalian cells.

Porcine zona pellucida glycoprotein (pZP1) is a good candidate for a contraceptive vaccine. For the purpose of producing glycosylated pZP1, several types of recombinant pZP1 proteins were produced in mammalian cell lines. In the first experiment, a minigene encoding pZP1 (681 amino acids) was designed for insertion into an expression vector and then transfected to three cell lines (293T, CHO-K1, and LLC-PK1). The resulting recombinant proteins were highly glycosylated and were localized in the cytoplasm. To produce a secretory type of recombinant pZP1, in the second experiment, a cDNA coding for pZP1 excluding a putative transmembrane region and a smaller cDNA coding for 1-198 amino acid residues of pZP1 were designed to produce fusion proteins with the human IgG1 heavy chain. The resultant recombinant proteins were secreted into the supernatant from both transfected cell cultures. Recombinant secretory proteins are useful because of their simple affinity purification.

Animals↗