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Biomedical subjects

S Sakamoto

Publications and source records attributed to S Sakamoto.

At least 271 records · Page 15Linked to original sources
PubMed1996

[Evaluation of valvular lesions by three-dimensional echocardiography].

A recently developed, on-line image processing system (Tomtec EchoScan) for three-dimensional (3D) echocardiography was compared with conventional two-dimensional examination and our own off-line 3D system. Transesophageal echocardiography was performed in 10 cardiac patients using an omniplane transducer which was automatically rotated under the control of the 3D system. At each angle of the transducer, the respiration-gated image of one cardiac cycle was acquired and transferred into the computer, where the dynamic 3D images of mitral and/or aortic valve were reconstructed. The EchoScan system enabled 3D recognition of the structural and dynamic abnormalities of the valves, such as mitral valve prolapse, although tissue information, which is expressed as a gray scale in the conventional echocardiography, cannot be evaluated from the 3D image. Average times were 5.4 min for the data acquisition, 11.8 min for the 3D processing and 5.7 min for the rendering. Although it seems necessary to improve the efficacy of data acquisition, to shorten the calculation time and to minimize the artifacts, this system enables assessment of 3D cardiac structures at the bedside and to fully recognize valvular lesions preoperatively in patients with valvular heart disease.

Aged↗
PubMed1995

Effective anticoagulation by argatroban during immunoadsorption therapy for malignant rheumatoid arthritis with a high polymorphonuclear leukocyte elastase level.

Polymorphonuclear leukocyte elastase (PMNE) is a glycoprotein with a molecular weight of about 30000 and exists in 3 isozymes (1). It has a biological role in host defense mechanisms, but it sometimes induces abnormal blood coagulation and injury of the vascular intima (1,2). We were not able to obtain a satisfactory anticoagulant effect when using heparin during immunoadsorption therapy in a patient with malignant rheumatoid arthritis and high PMNE level, but found that argatroban, a selective antithrombin agent, produced satisfactory anticoagulation. This finding is interesting as far as the various pathologic roles of PMNE are attracting increasing clinical attention (1,2,3).

Antithrombins↗
PubMed1995

Establishment and molecular characterization of a novel leukemic cell line with Philadelphia chromosome expressing p230 BCR/ABL fusion protein.

The cell line AR230 was established from the peripheral blood mononuclear cells of a patient with chronic myeloid leukemia and t(9;22) translocation bearing a variant type of BCR/ABL rearrangement. AR230 expresses a BCR/ABL fusion protein with a molecular mass of 230 kilodaltons (kDa) due to the insertion of 180 amino acids encoded by 3' exons of BCR (b4 to c3). An immune complex kinase assay showed that the 230-kDa BCR/ABL protein ahd autophosphorylation activity. Immunoprecipitation analysis revealed a stable complex of GRB2 and 230-kDa BCR/ABL proteins, indicating that the Ras activation pathway is involved in the process of transformation. AR230 expressed another short transcript consisting of a BCRc2/ABL junction, which is associated with a stop signal shortly after the junction. To our knowledge, this is the first cell line expressing a 230-kDa fusion product of BCR/ABL. AR230 will be useful for studying the biological function of divergent BCR/ABL proteins.

Amino Acid Sequence↗
PubMed1995

Influence of alpha-deoxyadenosine on the stability and structure of DNA. Thermodynamic and molecular mechanics studies.

The alpha anomer of deoxyadenosine (alpha) and an abasic site (tetrahydrofuran, F), which are DNA lesions produced by free radicals, were site-specifically incorporated in 9-mer duplexes d(TGAGXGTAC).d-(GTACNCTCA), where X = alpha or F and N = A, G, C, or T. Their influence on thermodynamic stability and structure of DNA was assessed by UV-melting measurements and molecular mechanics calculations. UV-melting studies revealed that a duplex containing an alpha T pair was as stable as the parental duplex containing an AT pair at the same site. Furthermore, the stability of duplexes containing alpha varied depending on the base opposite this lesion, with the Tm decreasing in the following order: alpha T > alpha C approximately alpha A > alpha G. On the contrary, an abasic site introduced in the same site showed a significantly greater destabilizing effect than alpha, but variation of Tm with the bases opposite F was less evident. To delineate the molecular mechanism of thermodynamic effects of an alpha lesion, molecular mechanics calculations were performed for the same duplexes as used for UV-melting measurements. The results suggest that the structural perturbation introduced into DNA by an alpha N pair is alpha G > alpha A > alpha C > alpha T, showing a parallel correlation with the destabilizing effects of alpha N pairs. On the basis of these results, it is discussed how the perturbations introduced by these DNA lesions may influence the selection of nucleotides opposite the lesions by DNA polymerases and the interaction with DNA repair enzymes such as Escherichia coli endonuclease IV and exonuclease III.

Base Sequence↗
PubMed1995

Dramatic hyperplasia of mtv-2+ lymph node grafts in mtv-2- recipients and selective stimulation of V beta 14+ T cells in recipients' lymph nodes in the DDD mouse.

DDD/1 (DDD) mice contrast strikingly with DDD-mtv-2/mtv-2 (DDD-mtv-2) congenics in their marked lymph node (LN) T cell paucity. To clarify the possible difference in LN function between them, reciprocal LN grafting experiments were conducted. DDD-mtv-2 LN grafts in DDD recipients underwent hyperplasia as dramatic as 10-to 20-fold increase in weight between 3 and 4 wk after implantation. Lymphoid cells in hyperplastic LN grafts were of recipient origin. Similar hyperplasia of mtv-2-heterozygous LN grafts also occurred on various hybrid backgrounds involving DDD mice. Moreover, LN grafts from BALB/c mice infected with mtv-2-derived exogenous mouse mammary tumor virus (MMTV) swelled in MMTV-free BALB/c recipients. Genetic analysis of DDD x (DDD x DDD-mtv-2)F1 backcross progeny demonstrated that LN hyperplasia was closely linked to mtv-2. The frequencies of V beta 5+ and V beta 8+ T cells unresponsive to mtv-2-encoded superantigen (SAg) changed with practically the same kinetics in both LN grafts and recipients' LN. Thus, the cells responsible for LN hyperplasia were polyclonal. V beta 14+ CD4+ cells responsive to mtv-2 SAg were specifically stimulated in recipients' LN but selectively deleted in hyperplastic LN grafts. DDD mice carrying hyperplastic mtv-2+ LN grafts or pretreated with mtv-2+ spleen cells developed an unresponsive state in terms of influx of mtv-2- lymphoid cells into mtv-2+ LN grafts. These results indicate that mtv-2 gene products including SAg may stimulate mtv-2- lymphoid cells of recipients and cause them to migrate into mtv-2+ LN grafts in a nonspecific manner with resulting LN hyperplasia.

Animals↗
PubMed1995

On the mechanism of preferential incorporation of dAMP at abasic sites in translesional DNA synthesis. Role of proofreading activity of DNA polymerase and thermodynamic characterization of model template-primers containing an abasic site.

DNA polymerase preferentially incorporate dAMP opposite abasic sites (A-rule). The mechanism of the A-rule can be studied by analyzing three dissected stages of the reaction including (i) initial nucleotide insertion, (ii) proofreading excision of the inserted nucleotide and (iii) extension of the nascent primer terminus. To assess the role of the stage (ii) in the A-rule, kinetic parameters of the proofreading excision of primer terminus nucleotides opposite abasic sites were determined using E.coli DNA polymerase I Klenow fragment. The relative efficiency of the excision (Vmax/Km) revealed that removal of A was the least favored of the four nucleotides, but the differences in the efficiencies between excision of A and the other nucleotides was less than 2-fold. In addition, in an attempt to reconcile kinetic data associated with the stage (i) or (ii), the differences in free energy changes (delta delta G degrees) for the formation of model template-primer termini containing XN pairs (X = abasic site, N = A, G, C or T) were determined by temperature dependent UV-melting measurements. The order of delta delta G degrees was XG > XA = XC > or = XT, with delta delta G degrees being 0.5 kcal/mol for the most stable XG and the least stable XT. Based on these data, the role of the stage (ii) and energetic aspects of the A-rule are discussed.

Base Sequence↗
PubMed1995

Cloning and sequencing of cellulase cDNA from Aspergillus kawachii and its expression in Saccharomyces cerevisiae.

The cDNA encoding the endo-beta-1,4-glucanase (carboxymethylcellulase; CMCase-I) from Aspergillus kawachii IFO 4308 was cloned. Nucleotide-sequence analysis of the cloned cDNA insert showed a 717-bp open reading frame that encoded a protein of 239 amino-acid residues. The predicted amino-acid sequence of the mature protein had considerable homology with the protein sequence of the FI-CMCase of Aspergillus aculeatus. The cDNA was introduced into Saccharomyces cerevisiae. The expressed enzyme had carboxylmethylcellulase activity, identified by clear zones on a CMC-agar plate after Congo Red staining.

Amino Acid Sequence↗
PubMed1995

Monokine production by peripheral whole blood in chronic hepatitis C patients treated with interferon.

Using our scoring system, we studied the production of monokines (interleukin-1 alpha, interleukin-1 beta, tumor necrosis factor-alpha, and interleukin-6) by lipopolysaccharide-stimulated peripheral whole blood in 34 patients with chronic hepatitis C during the interferon-alpha/beta therapy. It decreased in 25.7% (9/35 group A), fluctuated in 60.0% (21/35, group B), and increased in 14.3% (5/35, group C). The patients in group A were younger than those in group B (P < 0.05). The histological grade of injury was milder in group A than in group B or C. The rate of sustained response was 66.7% (6/9) in group A, 19.0% (4/21) in group B, and 40.0% (2/5) in group C(P = 0.0184, group A versus group B). In summary, monokine production by peripheral whole blood varied during interferon therapy for chronic hepatitis C patients. No significant change was noted in 60% of the patients. However, patients with decreased monokine production were younger, with a mild histological grade, and likely to respond to the interferon therapy.

Adult↗
PubMed1995

Severe chronic active hepatitis induced by UFTR containing tegafur and uracil.

A 77-year-old female patients developed severe hepatic injury after the administration of UFTR, which contains tegafur and uracil, for postoperative chemotherapy of colon cancer. Liver damage was recognized 10 months after its administration. Serum markers for viral hepatitis and various autoantibodies were negative. The wedged biopsied liver specimen revealed advanced chronic active hepatitis with periportal confluent necrosis, marked intralobular spotty necrosis, and significant proliferation of pseudo-bile ductules. Although the cessation of the drug and conservative therapies improved hepatic function, an accidental readministration of UFTR caused her severe hepatic damage again. These findings suggest that liver injury in the present case was caused by UFTR. Histological findings were unique. Although tegafur is known to worsen hepatic function when given to patients with liver cirrhosis, UFTR may also cause severe hepatic injury in those without preexisting liver disease.

Aged↗
PubMed1995

Mapping and characterization of a sequential epitope on the rabies virus glycoprotein which is recognized by a neutralizing monoclonal antibody, RG719.

We have established a murine hybridoma cell line RG719 which produces a rabies virus-neutralizing IgM-type monoclonal antibody (referred to as MAb RG719). Immunoblot analysis indicated that the antibody recognized a sequential epitope of G protein. Among four rabies virus strains tested, the antigenicity to MAb RG719 was absent from the Nishigahara strain, while the other three strains (HEP, ERA and CVS) reacted to the MAb. Studies with deletion mutants of the G protein indicated that the epitope was located in a middle region of the primary structure of G protein, ranging from position 242 to 300. By comparing the estimated amino acid sequence of the four strains, we found in this region two amino acids (at positions 263 and 291) which are common to three of those strains but are not shared by the Nishigahara strain. The site-directed point mutagenesis revealed that replacement of phenylalanine-263 by leucine destroyed the epitope of the HEP G protein, while the epitope was generated on the Nishigahara G protein whose leucine-263 was replaced by phenylalanine. These observations suggest that phenylalanine-263 is essential for constructing the epitope for MAb RG719. The synthetic 20-mer peptide produced by mimicking the amino acid sequence (ranging from amino acid positions 249 to 268) of the presumed epitope region was shown to bind specifically to MAb RG719 and also to raise the virus-neutralizing antibodies in rabbits. Vaccination with the HEP vaccine produced in Japan induced in humans and rabbits production of significant amounts of the antibodies which reacted with the 20-mer peptide.

Amino Acid Sequence↗
PubMed1995

Transformation into acute basophilic leukaemia in a patient with myelodysplastic syndrome.

We describe a patient with basophilic leukaemia following a 2-year period with myelodysplastic syndrome (refractory anaemia). The marrow showed 59.4% of blasts with 25.0% of mature and immature basophils. The leukaemic blasts contained granules, positively stained with toluidine blue but negative for peroxidase. The basophilic differentiation was confirmed by ultrastructural analysis demonstrating immature basophil granules. In addition, a morphological transition from immature blasts to more mature basophils was observed. Immunophenotypic analysis of blasts and basophils showed positive for CD5, CD7, CD13, CD33 and CD34. Cytogenetic investigation showed an abnormal karyotype, 46,XY,del(5)(q31q35), in 11% of the cells examined when the initial diagnosis of refractory anaemia was made. However, expansion of the same clone up to 100% was observed concomitantly with transformation to basophilic leukaemia.

Anemia, Refractory↗
PubMed1995

Role of sinusoidal endothelial cells in liver disease.

We characterized the structural changes of sinusoidal endothelial cells in chronic ethanol-fed rats and rats with cirrhosis induced by thioacetamide. The phenotypic changes of sinusoidal endothelial cells in fibrotic rats induced by thioacetamide and the reversibility of these changes were also investigated under transmission and scanning electron microscopy, regular microscopy and by immunohistochemistry with laminin and von Willebrand factor antibodies. The diameter and porosity of sinusoidal endothelial fenestrations were increased in chronic ethanol-fed rats without liver fibrosis, however, they decreased within 4 weeks of the cessation of thioacetamide treatment. A basement membrane-like structure in Disse's space was noted 6 weeks after thioacetamide treatment. Laminin was detected in Disse's space after 4 weeks and von Willebrand factor was detected in the cytoplasm as granular fluorescence after 6 weeks of thioacetamide treatment. Reversibility of the phenotypic changes of the sinusoidal endothelial cells was demonstrated in fibrotic liver of rats that received thioacetamide for 6 weeks after long-term discontinuation of thioacetamide administration. These results indicate that the structural and immunohistochemical characteristics of sinusoidal endothelial cells change in chronic ethanol-fed rats and fibrotic rats and these changes are reversible.

Alcoholism↗