PubMed Health⌕ Search

Biomedical subjects

N Sakata

Publications and source records attributed to N Sakata.

At least 91 records · Page 5Linked to original sources
PubMed1996

Results of single and double autografts for high-risk neuroblastoma patients.

Although intensive therapy with autologous bone marrow transplantation (ABMT) has improved the outcome of advanced neuroblastoma, nearly half the patients with this disease still relapse after a single ABMT. In our previous study, 10 of 22 patients relapsed within 16 months post-transplantation. Predictive risk-factors for relapse were the presence of bone lesions at diagnosis, and a minor response or progressive disease at transplantation. In order to improve the outcome of these high-risk patients, we tested the feasibility of double autografts. To date, eight patients have been treated, and no treatment-related deaths were observed. Six remain in CR or with stable disease for 6 to 29 months. Although more cases and longer observation are needed to draw conclusions, these results are encouraging.

Bone Marrow Transplantation↗
PubMed1996

Relation of C4b-binding protein to athero-sclerosis of the descending thoracic aorta.

C4b binding protein (C4bp) is a regulator of the classical pathway of the complementing system. It forms a complex with protein S which serves as a cofactor of coagulation inhibitor, protein C. We have reported that C4bp is an acute phase reactant and associated with total cholesterol and triglyceride concentrations (Biochim. Biophys. Acta 963 (1988) 98-108). This suggests a possible association of C4bp with athero-sclerosis. We examined the relation of C4bp levels and the severity of atherosclerosis of the descending thoracic aorta in 98 Japanese men. The severity of aortic atherosclerosis was assessed by average sclerotic length (ASL) and average sclerotic area (ASA), using transesophageal echocardiography. After adjustment for age, C4bp levels increased significantly with increasing ASL and ASA. The association remained significant even after adjusting for total cholesterol, hypertension, smoking, drinking, body mass index, fasting blood sugar, and uric acid. Immunohistochemical analysis of specimens of the descending thoracic aorta from autopsies, demonstrated the presence of C4bp in the foamy macrophages of fatty streaks and the necrotic core of atheromatous plaque. These findings indicate that the serum level of C4bp can serve as an independent indicator of aortic athero-sclerosis.

Adult↗
PubMed1995

Selective activation of c-Jun kinase mitogen-activated protein kinase by CD40 on human B cells.

The B cell surface antigen receptor, surface IgM (sIgM), is involved in B cell activation and proliferation. CD40 is involved in regulating IgE production and B cell survival. Cross-linking of B cell sIgM activates the Ras/Raf/p42erk2 pathway. In contrast, ligation of CD40 by antibody or soluble gp39 (CD40 ligand) leads to activation of the c-Jun kinase (JNK)/stress-activated protein kinase pathway. JNK/stress-activated protein kinase activation correlated with the stimulation of MEK kinase activity. CD40 does not activate the p42erk2 pathway, and sIgM fails to regulate the JNK/stress-activated protein kinase pathway in B cells. Thus, two important cell surface receptors involved in controlling specific B cell response differentially regulate sequential protein kinase pathways involving different members of the mitogen-activated protein kinase family. Anti-CD40 also rescued B cell apoptosis induced by anti-IgM. CD40 ligation did not affect the sIgM stimulation of p42erk2 activity. Conversely, sIgM ligation did not influence CD40 stimulation of JNK/stress-activated protein kinase. These results suggest that independent, parallel protein kinase response pathways are involved in the integration of sIgM and CD40 control of B cell phenotype and function.

Antibodies↗
PubMed1995

Oxidized low density lipoprotein stimulates collagen production in cultured arterial smooth muscle cells.

We examined the interactive effect of oxidized low density lipoprotein (LDL) and ascorbic acid on collagen production in cultured smooth muscle cells (SMCs). Porcine aortic SMCs were incubated with 50-200 micrograms/ml of human LDL with/without 5 microM Cu2+ for 24 h. Collagen production was assayed by successive salt precipitation at acidic and neutral pH after pepsin digestion of 3H-proline-labeled collagenous protein. Oxidation of LDL was evaluated by electrophoresis and by the level of thiobarbituric acid reactive substances (TBARS). Ascorbic acid reduced the oxidation of LDL + Cu2+ (53% reduction). In the presence of ascorbic acid, no differences were noted in collagen production between LDL and LDL + Cu2+. Without ascorbic acid, collagen production with LDL + Cu2+ was increased dose-dependently up to 6-fold with 150 micrograms/ml LDL, while no such effects were observed at any doses of native LDL. The addition of butylated hydroxytoluene to LDL + Cu2+ strongly suppressed oxidation (88% reduction), and significantly reduced collagen production close to that seen with native LDL. These results indicate that oxidized LDL stimulates collagen production in SMCs, while native LDL does not. Therefore, oxidized LDL may play a direct role in stimulating collagen production in SMCs, which could lead to collagenosis in atherosclerosis.

Animals↗
PubMed1995

Nonenzymatic glycation and extractability of collagen in human atherosclerotic plaques.

The relationship between the extractability of collagen by enzymatic digestion and the degree of nonenzymatic glycation of collagen was examined in the aorta and skin from 38 subjects without diabetes mellitus (mean age: 62.3 +/- 20.2 years). Samples were obtained from the aortic media (M), lesion-free intima (I), atherosclerotic intima (A) and dermis of the skin (S). Collagen was extracted first by incubation with 1/50 (enzyme/substrate weight ratio) pepsin at 4 degrees C for 24 h (P-fraction) and then by incubation with 1/10 (enzyme/substrate weight ratio) pepsin at room temperature for 24 h (EP-fraction). The pepsin-insoluble precipitates were digested by incubation with 270 units of bacterial collagenase at 37 degrees C for 24 h (PIS-fraction). Collagen contents, ketoamines and collagen-linked fluorescence (CLF) were measured in each fraction. The amount of ketoamines and the level of CLF correlated inversely with the susceptibility of collagen to pepsin digestion in various tissues, including M, I, A and S. These values were highest in both the P- and EP-fractions of M, which contained the least amount of collagen extracted by pepsin digestion. In contrast, they were lowest in S, where the concentration of collagen extracted by pepsin digestion was greatest among all of the tissue samples. Atherosclerotic intima (A) and aortic media (M) showed an age-related increase in the total amount of collagen digested with pepsin and collagenase, which depended mainly on an increase in the content of pepsin-insoluble collagen. Although the total amount of collagen did not increase with advancing age in I or S, collagen in I and S became progressingly resistant to pepsin digestion. These results suggest that the age-related decrease in the susceptibility of collagen to pepsin digestion may be due to nonenzymatic glycation in atherosclerotic lesions as well as normal tissues, including the aortic media, lesion-free intima and skin. The level of CLF significantly increased with age in the P-fraction and/or EP fraction of M, I and S. However, there was no relationship between the level of CLF and the subject's age in A. Thus, the accumulation of advanced glycation endproducts (AGEs) on collagen fibers may be partially responsible for the increase in collagen matrix in atherosclerotic lesions of subjects without diabetes mellitus.

Adolescent↗
PubMed1995

Age-related changes in surface antigens on peripheral lymphocytes of healthy children.

The age-related changes in proportion of various subsets within lymphocytes were investigated in cord blood and peripheral blood from healthy children and adults. The percentages of T and B cells did not show age-related changes, whereas natural killer (NK) cells increased significantly with age. Within lymphocytes or the CD3+ T cell population the proportion of CD45RAbright+ lymphocytes decreased and that of CD45RO+ cells increased, while that of CD45RAdim+ cells showed no age-related change. Within lymphocytes, the percentage of CD45RAbright+ CD4+ cells decreased, together with a decline of that of CD4+ cells. The proportions of CD45RAbright+ CD8+ cells and S6F1bright+ CD8+ cells increased with age, and the age-dependent increase of the proportion of CD8+ cells seems to be mainly attributable to the increases in these subsets. The CD45RAdim+ CD4+ and CD45RAdim+ CD8+ cells co-expressing CD45RO at a low level nevertheless showed no age-related changes. In gamma delta T cells, both delta TCS1+ and delta TCS1- T cells increased with age, but the delta TCS1- gamma delta T cells increased more than the delta TCS1+ subset. Among lymphocytes, the percentages of CD20+, CD21+ and CD22+ cells remained similar, with no age-related changes, but the proportion of CD5+ cells within lymphocytes or B cells decreased. The proportions of CD16+ NK cells among lymphocytes increased with age, and this change was attributable to the increase of CD56+ cells.

Adolescent↗
PubMed1995

Anti-HLA antibody screening with extracted platelet HLA antigens by the mixed passive hemagglutination method.

For the detection of anti-HLA antibody in the serum of patients receiving frequent platelet transfusions, we developed a new method in which platelet antigens are extracted into physiological saline containing 3% sucrose and coated as a layer on a U-type Terasaki plate. In the present study, screening of anti-HLA antibodies was conducted with this plate by the mixed passive hemagglutination test although the plate contained both HLA and HPA. The reactivity determined by this method correlated well with antihuman immunoglobulin-lymphocyte cytotoxicity test (AHG-LCT) results (r = 0.963). The plate can be preserved for at least 2 years at -80 degrees C and is easier to handle than the frozen lymphocyte panels used in the LCT test in which lymphocytes must be kept alive. This new method is an alternative way to screen HLA antibodies. In addition, it is expected that this method will be used to screen anti-HPA antibodies.

Blood Platelets↗
PubMed1995

[Aging of aorta and atherosclerosis--role of nonenzymatic glycation of collagen].

In order to clarify the role of the nonenzymatic glycation of the collagen matrix in aging of the aorta and atherogenesis, we studied the relation between ketoamine or advanced glycation end-products (AGEs) and the solubility of collagen in human skin and aorta. AGEs were measured as a collagen-linked fluorescence (excitation wavelength: 370 nm. emission wavelength: 440 nm). There was a positive correlation between the level of AGEs and subjects' age in skin and aortic media. Collagen became more insoluble with increase in the amount of ketoamine and AGEs. Collagen was more resistant to pepsin digestion in atherosclerotic intima than in other tissues including aortic media, lesion-free intima and skin. Diabetic rats showed an accumulation of collagen in aortic media at 28 weeks after an injection of streptozotocin. Moreover, they increased the percentage of insoluble collagen to total collagen and the amount of AGEs binding to insoluble collagen in aortic media. In contrast, the amount of ketoamine of insoluble collagen was increased in diabetic rats at 16 weeks as compared to control. There was no difference in DNA contents of cultured smooth muscle cells between glycolaldehyde-modified and non-modified matrices. However, the activity of type I collagenase (inactive form) of smooth muscle cells decreased on glycolaldehyde-modified type I collagen as compared to that on non-modified collagen. These results suggest that AGEs contribute to the accumulation of collagen in atherosclerotic lesions and aged aorta through the insolubility of collagen and the inhibition of collagenase activity of smooth muscle cells.

Adult↗
PubMed1995

Effects of cytogenin on spontaneous arthritis in MRL/1 mice and on pristane-induced arthritis (PIA) in DBA/1J mice.

Cytogenin, 8-hydroxy-3-hydroxymethyl-6-methoxyisocoumarin, has low cytotoxicity on murine and human tumour cells in vitro. It augments or suppresses phagocytosis of macrophages and lymphocyte proliferation. It has been reported that cytogenin has a potent inhibitory effect clinically on adjuvant arthritis in Lewis rats and on type II collagen-induced arthritis in DBA/1J mice. Our experimental findings provide evidence that cytogenin has beneficial effects on spontaneous polyarthritis in MRL/1 mice and pristane-induced arthritis in DBA/1J mice. The results suggest that the mode of the anti-arthritic action of cytogenin is different from those of NSAIDs; although the precise mode of action remains unclear, cytogenin may become an excellent therapeutic agent for rheumatoid arthritis.

Animals↗
PubMed1994

Evidence for a lack of regulation of the assembly and secretion of apolipoprotein B-containing lipoprotein from HepG2 cells by cholesteryl ester.

Although some previous studies have suggested that triglyceride, a major core lipid, plays a key role in the assembly and secretion of apolipoprotein B-containing lipoproteins from HepG2 cells, other reports have indicated the importance of cholesteryl ester, another core lipid. We attempted to better define the roles of triglyceride and cholesteryl ester in the assembly and secretion of apolipoprotein B-containing lipoproteins from HepG2 cells by determining the effects of Sandoz 58-035, a potent acyl-CoA acyltransferase inhibitor, which significantly inhibits cholesteryl synthesis, and Triacsin D, a potent fatty acyl-CoA synthetase inhibitor, which significantly inhibits triglyceride synthesis, on the secretion of apolipoprotein B-containing lipoproteins. Sandoz 58-035 (2 micrograms/ml) decreased very low density lipoproteins (VLDL)-stimulated cellular cholesteryl ester content by 60-80%, and blocked oleate-stimulated cholesteryl ester synthesis by 100%, but did not decrease VLDL- or oleate-stimulated apolipoprotein B secretion. Triacsin D (12.5 microM), which significantly inhibited VLDL and oleate stimulation of triglyceride synthesis, without affecting cholesteryl ester synthesis, blocked the stimulation of apolipoprotein B secretion by both agents. In HepG2 cells transfected with 3-hydroxy-methylglutaryl-CoA reductase cDNA, cholesteryl ester synthesis and mass were increased by 100%, but apolipoprotein B secretion was unaffected. Sandoz 58-035 decreased cholesteryl ester synthesis significantly but did not decrease apolipoprotein B secretion from this cell line. When these transfected cells were incubated with oleate, apolipoprotein B secretion increased; Triacsin D blocked this effect. Finally, sphingomyelinase treatment (which shifts cholesterol from plasma membranes to intracellular pools) increased cholesteryl ester synthesis 4-5-fold, but apolipoprotein B secretion was unaffected. Changes in cellular cholesteryl ester synthesis or mass did not affect the intracellular degradation of newly synthesized apolipoprotein B, but changes in triglyceride synthesis were always associated with corresponding changes in the intracellular degradation of apolipoprotein B. In conclusion, neither long term nor short term changes in cholesteryl ester synthesis or mass regulate the assembly and secretion of apolipoprotein B-containing lipoprotein from HepG2 cells.

Acetates↗
PubMed1994

PDGF-like growth factor from SV40-transformed smooth muscle cells promotes growth in an autocrine or paracrine manner.

We investigated the growth characteristics of smooth muscle cells transformed by oridefective simian virus 40 plasmid DNA (TSMCs). TSMCs demonstrated a significantly higher proliferative activity when compared with nontransformed smooth muscle cells (SMCs). The SMCs were not able to proliferate in media with 5% plasma-derived serum (PDS) instead of fetal bovine serum, while TSMCs grew under this condition. When the DNA synthesis of quiescent SMCs was reinitiated by the addition of serum or platelet-derived growth factor (PDGF), the amount of [3H]thymidine incorporation into DNA varied with the concentrations of serum or PDGF and decreased on type V collagen compared with the other collagen substrates. In contrast, the TSMCs showed no differences in the amount of [3H]thymidine incorporation into DNA among the various concentrations of serum or PDGF and different types of collagen. When quiescent SMCs were cocultured with TSMCs, they showed a remarkable increase in the amount of [3H]thymidine incorporation into DNA, which was most intensively inhibited by type V collagen. These results suggest that TSMCs can promote the growth of TSMCs and SMCs in either an autocrine or paracrine manner and that they proliferate independently of the collagen matrices. Trapidil, a pyrimidine derivative that may inhibit the action of PDGF, decreased the number and cAMC levels of TSMCs in the media with 5% PDS in a concentration-dependent manner. The addition of polyclonal anti-PDGF-B antibody induced up to 59.5% inhibition of enhancement of DNA synthesis of SMCs cocultured with TSMCs. The level of cyclic adenosine monophosphate (cAMP) increased in the TSMCs compared with the SMCs. There was, however, no difference in the cAMP levels of either cells between the various types of collagen. Thus, the release of PDGF-like growth factor and an accumulation of cellular cAMP may be related to an increased DNA synthesis of TSMCs.

Animals↗
PubMed1994

Comparative measurement of myocardial ATP and creatine phosphate by two chemical extraction methods and 31P-NMR spectroscopy.

Changes in ATP and creatine phosphate levels during early (up to 150 s) global ischaemia were determined in isolated rat hearts by two chemical extraction methods (a conventional direct perchloric acid extraction and a stepwise extraction using alcohol and perchloric acid solutions) and by qualitative 31P-NMR. No difference in the ATP level hardly changed up to 40 s of ischaemia when measured by the three methods, and slightly decreased at 150 s of ischaemia. In contrast to ATP, creatine phosphate content in the normally perfused tissue was observed to be higher by the stepwise extraction (68-73 nmol/mg protein) than by direct perchloric acid extraction (55 nmol/mg protein). The creatine phosphate rapidly decreased to about 50% of normal value at 40 s of ischaemia, and the difference in the normal creatine phosphate content using the two chemical methods disappeared with the progression of ischaemia. Thus, the creatine phosphate more rapidly decreased when observed by the stepwise method than by the other two methods in this ischaemic condition. These results suggest that (1) creatine phosphate exists in an undetermined chemical state (perhaps neither in simple soluble form nor in so-called "bound" form) in rat cardiac myocytes, and (2) the stepwise extraction method is useful to measure the content of energy metabolites and to examine the intracellular chemical state in cardiac tissues.

Adenosine Triphosphate↗
PubMed1994

Low density lipoproteins bind more to type I and III collagens by negative charge-dependent mechanisms than to type IV and V collagens.

The accumulation of low density lipoprotein (LDL) in the arterial intima is an important characteristic of atherosclerosis. We investigated the mechanisms by which LDL binds to different types of collagen. The binding activities of 125I-labeled human native LDL (nLDL) and copper-oxidized LDL (oxLDL) with different collagen gels prepared in type I collagen-based mixtures with types I, III, IV and V (I+I, I+III, I+IV and I+V, respectively) were examined. A concentration of 20 micrograms LDL protein/150 micrograms collagen/well was used. The diffusion of both nLDL and oxLDL into the collagen gels reached an equilibrium after 48 h. All of the collagen gels showed the same rates of diffusion with both LDLs. The binding activities of oxLDL were significantly greater than those of nLDL (P < 0.001%), while the binding activities for both LDLs followed the order I+I and I+III > I+V > I+IV. However, the increased binding rate of oxLDL compared to nLDL was 1.66 for I+IV, 1.50 for I+V, 1.33 for I+I and 1.19 for I+III. When a 10-fold higher dose of NaCl (1 M) was added to the oxLDL medium, the binding rate of oxLDL was reduced (rate of reduction: 52% (I+I), 48% (I+III), 35% (I+IV), 13% (I+V)). These results suggest that oxLDL binds more to type I and III collagens by negative charge-dependent mechanisms than to type IV and V collagens. Therefore, types I and III collagens may play an important role in trapping LDL, especially oxLDL. Therefore, oxidatively modified LDL may contribute to atherogenesis due to its longer retention in the arterial wall.

Arteriosclerosis↗
PubMed1994

Changes in SH reactivity of the protein in porcine intestinal brush-border membranes associated with lipid peroxidation.

The effects of lipid peroxidation on the SH reactivity of the proteins in porcine intestinal brush-border membranes were examined using a fluorogenic thiol reagent, N-[7-dimethyl-amino-4-methylcoumarinyl]maleimide (DACM) in relation to lipid organization. Changes in the lipid organization were assessed by measurement of the rate of incorporation of 1,6-diphenyl-1,3,5-hexatriene (DPH) into the membrane lipids and the fluorescence anisotropy of DPH-labeled membranes. Treatment of the membranes with an oxygen-radical-generating system, i.e., ascorbic acid/Fe2+/tert-butyl hydroperoxide (t-BuOOH), resulted in decrease in the rate of DACM incorporation into the SH groups of the membrane proteins (DACM-labeling) and the amount of DACM labeled to the SH groups with a decrease in the lipid fluidity, depending on the formation of thiobarbituric acid-reactive substances and conjugated diene. Pretreatment of the membranes with diphenylamine effectively prevented the ascorbic acid/Fe2+/t-BuOOH-induced decreases in the DACM-labeling and DPH incorporation rates, whereas neither superoxide dismutase, catalase, sodium benzoate, nor mannitol showed a protective effect. The contribution of the lipid fluidity to the SH reactivity to DACM of the proteins in the membranes with different levels of lipid peroxidation was further examined using a lipid fluidizer, benzyl alcohol. The results showed that the DPH incorporation rate increased in proportion to increasing concentrations of the alcohol regardless of the peroxidation level of the membranes, whereas the susceptibility of the SH reactivity of the membrane proteins as to benzyl alcohol transitionally changed as the membranes were peroxidized to levels greater than 400 nmol conjugated diene/mg protein.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Human plasma fibronectin possesses second binding site(s) to Staphylococcus aureus on its C-terminal region.

The existence of a second binding site to Staphylococcus aureus on fibronectin was explored by using a recombinant protein, alb-FnBPA, which was obtained from an Escherichia coli clone containing a part of the gene for fibronectin-binding protein of S. aureus. Limited digestion with trypsin produced a 215K fragment from the B chain of fibronectin by releasing an N-terminal 32 kDa region. This C-terminal large fragment captured alb-FnBPA in spite of lacking the N-terminal binding region to S. aureus. This treatment also produced a 185K fragment from A chain by releasing N-terminal 32 kDa and C-terminal 37 kDa regions, and the 185K fragment possessed no binding ability. Thermolysin digestion was also performed to investigate the effect on the binding of releasing the C-terminal region from both of the chains and to locate the binding region to alb-FnBPA on the tryptic 215K fragment. But this digestion produced no fragment binding to alb-FnBPA except for the N-terminal 24K and its transient precursory fragments. These results indicate that both the N-terminal and the C-terminal regions of fibronectin bind to S. aureus, and suggest that the binding appears to involve cooperation between type III repeats and C-terminal type I repeats.

Binding Sites↗
PubMed1994

Immunological recognition of fibronectin-binding proteins of Staphylococcus aureus and Staphylococcus capitis, strain LK 499.

Antibodies to fibronectin-binding proteins (FnBPs) of Staphylococcus aureus, including binding domain of FnBPA, the D region, or the A-C regions of FnBPB were produced in rabbits and mice. These antibodies were used to characterize cell-associated FnBPs of S. aureus strain Cowan I, S. aureus strain U320 and a coagulase-negative Staphylococcus capitis strain LK499 as well as extracellular FnBPs in culture supernatants of the strain U320. FnBPs of S. aureus were predominantly FnBPA, while FnBPB was hardly detected on the cells or in culture supernatant of these S. aureus strains. Moreover, S. capitis strain LK499 possessed different FnBP(s) compared to S. aureus because the antibodies to S. aureus FnBPs did not recognize FnBP(s) on S. capitis.

Adhesins, Bacterial↗