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Biomedical subjects

N Sakata

Publications and source records attributed to N Sakata.

At least 109 records · Page 6Linked to original sources
PubMed1994

Retarded fibronexus formation and cell attachment on type V collagen.

We previously found that type V collagen repressed the attachment and spread of aortic smooth muscle cells. The present study was carried out to investigate the effects of type V collagen on the formation of fibronectin and F-actin filaments of human dermal fibroblasts in relation to cell attachment and spread, using an immunofluorescent technique and morphometry. The number and area of the cells attached to type V collagen at 1 and 3 hours after seeding were significantly lower than those of cells on other substrates, including collagen types I, III and IV, and bovine serum albumin. However, there was no significant difference in the attachment and spread among the cells on these substrates after 24 hours. Cultured fibroblasts exhibited two patterns of fibronectin; one was a clear, linear fibronectin localized mainly in the cellular margins, and the other was a granular or flocculent fibronectin found in the perinuclear areas. The former was stained in non-permeabilized cells, but not in trypsin-treated cells (cell surface fibronectin). In contrast, the latter was not detected in nonpermeabilized cells, but was found in trypsin-treated cells (perinuclear fibronectin). Most of the cells cultured on type V collagen did not form either linear cell surface fibronectin or F-actin filaments at 3 hours. In contrast, many cells on collagen types I, III, and IV developed both cell surface fibronectin and F-actin filaments, the distributions of which were partially coincident. Colocalization of linear cell surface fibronectin and F-actin filaments was found in cells on all of the substrates after 24 hours. Perinuclear fibronectin showed similar patterns, and was not colocalized with F-actin filaments on different substrates at 3 and 24 hours of culture. Solid-phase substrates induced a better cellular attachment at 3 hours than serum adhesive factors. The administration of monensin, which inhibits the secretion of protein products, decreased the intensity of the fluorescence of cell surface fibronectin in fibroblasts, which was observed in a clear line. These results suggest that the retardation of the initial attachment and spread of fibroblasts on type V collagen is related to an inhibition in the formation of the fibronexus, a close transmembranous association of individual fibronectin fibers and F-actin filaments.

Actins↗
PubMed1994

Protective effects of verapamil and adenosine treatment on high energy phosphate metabolism in ischemic and reperfused myocardium.

Isolated rat hearts were subjected to retrograde perfusion to investigate the protective effects of adenosine and verapamil on the myocardium. In group 1, the perfusate was standard Krebs-Henseleit buffer solution. The perfusate was changed to Krebs-Henseleit buffer containing verapamil (100 nM) in group 2, adenosine (100 microM) in group 3 and both drugs in combination in group 4 for 30 min before ischemia and during 20 min of reperfusion. Group 2 displayed a recovery of creatine phosphate but not of ATP at the end of reperfusion. In group 4, the recovery of both ATP and creatine phosphate was significantly greater than in group 1. The coronary flow of group 4 was significantly higher than that of the other groups. Treatment with both verapamil and adenosine before and after global ischemia may protect the ischemic myocardium by improving high energy phosphate metabolism and coronary circulation.

Adenosine↗
PubMed1994

Oxidized LDL induces an increase in the relative collagen synthesis of rabbit aortic smooth muscle cells.

Cell degeneration and collagenosis are the main features in atherosclerotic plaque. We examined the effects of human low density lipoprotein (LDL) on cultured rabbit aortic smooth muscle cells (SMCs). Copper oxidized LDL (LDL+Cu) injured the SMCs more than did native LDL. Cytotoxicity of oxidized LDL was prevented by the simultaneous addition of butylated hydroxytoluene (BHT) and ethylenediamine tetraacetic acid. Collagen synthesis increased up to 6 fold after incubation with 200 micrograms protein/ml of both native and oxidized LDL compared with that incubated in bovine serum albumin. Noncollagen protein synthesis was significantly reduced by oxidized LDL when compared to that by native LDL. Therefore, oxidized LDL increased the relative collagen synthesis (3.33%) to a greater extent than did native LDL (0.72%). By adding BHT to LDL+Cu, the elevated relative collagen synthesis was reversed due to the restoration of noncollagen protein synthesis while it also inhibited LDL peroxidation as evaluated by the formation of malondialdehyde (MDA). However, sodium MDA (up to 200 microM) did not induce either cytotoxicity or an increase of relative collagen synthesis. We therefore conclude that oxidized human LDL enhanced the relative collagen synthesis coinciding with the induction of injury in cultured aortic SMCs, however free MDA may not be the component responsible for these effects.

Animals↗
PubMed1994

Effects of cytogenin, a novel anti-arthritic agent, on type II collagen-induced arthritis in DBA/1J mice and adjuvant arthritis in Lewis rats.

The anti-arthritic effects of cytogenin (8-hydroxy-3-hydroxymethyl-6- methoxyisocoumarin) on type II collagen-induced arthritis in DBA/1J mice and adjuvant arthritis in Lewis rats were examined. Prophylactic treatment with cytogenin (30, 100 mg/kg) had a potent inhibitory effect on type II collagen-induced arthritis. Prophylactic or therapeutic treatment with cytogenin (10, 30 and 100 mg/kg) also had a potent inhibitory effect on adjuvant arthritis. In contrast to nonsteroidal anti-inflammatory drugs (NSAIDs), cytogenin (10, 30 and 100 mg/kg) had neither an anti-inflammatory effect on carrageenan-induced paw oedema in rats nor an analgesic effect on acetic acid-induced writhing in mice. These results suggest that the mode of the anti-arthritic action of cytogenin is different from that of NSAIDs and that cytogenin may become a useful drug for the treatment of rheumatoid arthritis.

Animals↗
PubMed1994

Thin glomerular basement membrane in diabetic patients with urinary abnormalities.

To clarify the clinical and pathological significance of thin glomerular basement membranes (Thin-GBM) appearing in evident diabetics, we examined the renal biopsies from 179 diabetes mellitus (DM) patients with urinary abnormalities in which the number of non insulin dependent diabetes mellitus cases was 140 cases while the remaining 39 cases had insulin dependent diabetes mellitus. In addition, 17 of these cases were found to have either segmental or diffuse Thin-GBM by electron microscopy. The clinical and morphological parameters between the diabetics with Thin-GBM (DM-Thin-GBM) and the diabetics without Thin-GBM (the controls) were significantly different regarding DM duration (DM-Thin-GBM vs control: 5.3 +/- 5.5 vs 9.8 +/- 6.5 years, p < 0.01), Ccr (67.0 +/- 25.5 ml/min vs 45.6 +/- 24.4 ml/min, p < 0.01), the incidence of hematuria (52.9% vs 24.5%, p < 0.05) and hypertension (13.3% vs 51.3%, p < 0.05). The severity of glomerular damage was mild in the DM-Thin-GBM group as compared to the control. The renal survival rate from the onset of urinary abnormalities was higher in the DM-Thin-GBM group than in the control (p < 0.01). In the case of DM-Thin-GBM, the grade of proteinuria correlated with the mean width of the thickened GBM (p < 0.01) and the spread of the thickened GBM which was more than 500 nm in width (p < 0.001). The severity of microscopic hematuria correlated with the spread of the Thin-GBM (p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Basement Membrane↗
PubMed1994

[Two cases of thymic cyst].

Thymic cysts were diagnosed by thoracotomy in two women with leprosy, both 64 years old, within 12 months. Both were asymptomatic and an abnormal mediastinal shadow on an annual screening chest radiograph was a clue to the diagnosis in both cases. According to retrospective studies it took at least six or seven years for the thymic cysts to become large enough to be detected. Real-time echography was effective in the diagnosis of a cystic lesion in one case. Thymic cysts are important cystic lesions rarely found in the anterior mediastinum. A resective operation is thought to be indispensable to differentiate them from thymomas accompanied by large cystic degeneration and from thymic cysts accompanied by malignancies.

Female↗
PubMed1994

Exogenous VLDL stimulates apolipoprotein B secretion from HepG2 cells by both pre- and post-translational mechanisms.

Previous studies have suggested that oleic acid (OA), by increasing availability of triglyceride (TG) and/or cholesteryl ester (CE), increases the secretion of apolipoprotein B (apoB) from HepG2 cells. The present studies were conducted to determine the effect of exogenous very low density lipoproteins (VLDL), which can provide TG and cholesterol to cells and be returned to the liver after secretion, in the regulation of hepatic apoB secretion. Addition of exogenous VLDL (50 micrograms protein/ml) to culture media was found to significantly stimulate apoB secretion from HepG2 cells. This effect was observed consistently with VLDL isolated from either normal or hyperlipidemic subjects. The effects of addition of VLDL were compared to that of OA, which was previously shown to stimulate apoB secretion by a posttranslational mechanism. VLDL appeared to increase apoB secretion by two mechanisms; the dominant one being posttranslational. Thus, VLDL protected newly synthesized apoB from rapid intracellular degradation in a manner similar to OA. Although treatment with VLDL increased the mass of both TG and CE, 3-fold and 2.6-fold, respectively, it appeared that the increase in TG was the critical factor associated with increased apoB secretion. Triacsin D, which is a potent inhibitor of TG synthesis, significantly inhibited the VLDL-induced stimulation of apoB secretion. Inhibition of apoB secretion by Triacsin D was associated with the loss of the protective effect of VLDL on newly synthesized apoB. In addition to its posttranslational effects, exogenous VLDL also regulated apoB secretion at the pretranslational level. Thus, we also observed that VLDL treatment consistently increased synthesis of apoB protein by 20-30%, an effect that is not observed after treatment of HepG2 cells with OA. A sensitive solution hybridization/RNase protection assay indicated that the increased apoB synthesis was associated with a 20-30% increase in apoB mRNA in VLDL-treated HepG2 cells. OA treatment had no effect on apoB mRNA levels. We conclude that VLDL treatment stimulates apoB secretion in HepG2 cells primarily by supplying fatty acids for TG synthesis. However, 20-30% of the stimulatory effect was due to a second mechanism that appeared to be pretranslational. Based on studies with OA, it appears that some component of VLDL other than TG-derived fatty acid was responsible for this effect.

Apolipoproteins B↗
PubMed1994

Staphylococcus aureus fibronectin-binding proteins (FnBPs). Identification of antigenic epitopes using polyclonal antibodies.

Polyclonal antibodies against recombinant fibronectin-binding proteins (gal-FnBP A and ZZ-FnBP B) of Staphylococcus aureus were analyzed by both solid-phase and solution-phase methods. These antibodies were found to bind homologous antigen and to cross-react with heterologous antigen. It was also found that antibodies recognize native FnBP on the cell surface. It has been shown, by the inhibition assay, that the majority of antibodies recognize a fibronectin-binding D1-D2 sequence of FnBP A. Anti-FnBP A Fab fails to bind the D3 sequence, though this peptide used in a solution inhibits binding of fibronectin to immobilized FnBP A, similarly to D1 and D2 peptides. Since the anti-FnBP A antibodies are able to block fibronectin binding to staphylococci by about 50%, it is reasonable to assume that the bacterial receptor has additional binding sites outside the D domain.

Adhesins, Bacterial↗
PubMed1993

Proteolysis and lipid-facilitated translocation are distinct but competitive processes that regulate secretion of apolipoprotein B in Hep G2 cells.

Under lipid-poor conditions, most newly synthesized apolipoprotein B100 (apoB) undergoes rapid degradation in Hep G2 cells such that only a small fraction of newly synthesized apoB is actually secreted. Addition of oleate to Hep G2 culture medium stimulates apoB secretion by a post-translational mechanism. In the current studies we have explored oleate-stimulation of apoB secretion by using calpain inhibitor I, N-acetyl-leucyl-leucyl-norleucinal (ALLN), a compound that inhibits the intracellular degradation of 3-hydroxy-3-methylglutaryl-coenzyme A reductase and the T cell receptor alpha subunit. Preincubation of Hep G2 cells with ALLN (40 micrograms/ml) for 1 h markedly inhibited degradation of newly synthesized apoB. Whereas only 32% of newly labeled apoB remained intact (cells+medium) in control cells after a 10-min pulse with [3H]leucine followed by a 60-min chase, 84% of labeled apoB was intact in ALLN-treated cells. However, most of the ALLN-protected apoB remained intracellular, as ALLN did not stimulate the rate of apoB secretion over the control rate (12 versus 9.2%). Although secretion of apoB was not accelerated, the protection afforded by ALLN continued for several hours, and labeled apoB continued to be secreted over 3 h of chase after which secretion ceased. The protection afforded by ALLN resulted in 37% of labeled apoB secreted by 3 h compared to 15% in control cells. In contrast, simultaneous treatment of cells with ALLN and oleate both accelerated and increased total apoB secretion, such that 36% of initially labeled apoB was recovered in the medium by 60 min and 71% of labeled apoB was secreted by 180 min of chase. These data show that ALLN and oleate affect apoB metabolism by different mechanisms. Although ALLN can protect nascent apoB from rapid early intracellular degradation, it does not accelerate apoB secretion. In contrast, although our results can not rule out the possibility that oleate may directly inhibit proteolysis of apoB, oleate appears to protect apoB mainly by facilitating transport of apoB out of a protease-containing compartment associated with the endoplasmic reticulum.

Apolipoproteins B↗
PubMed1993

Isolation of human herpesvirus 7 from a child with symptoms mimicking chronic Epstein-Barr virus infection.

Human herpesvirus-7 (HHV-7), which is a newly identified human herpesvirus with an unknown pathologic role, was isolated from a 5-year-old boy suffering from fever, hepatosplenomegaly and pancytopenia. Although the clinical course was similar to that of chronic active Epstein-Barr virus infection, no viruses other than HHV-7 were isolated. This finding raises the possibility that HHV-7 played a pathogenic role in the present patient.

Child, Preschool↗
PubMed1993

Porcine vascular smooth muscle cells immortalized with SV40 ori-defective DNA: characteristics of cell growth and collagen synthesis.

A cell line derived from medial smooth muscle cells (SMC) was established from the porcine coronary artery by transfection with ori-defective simian virus 40 plasmid DNA (SV40 DNA). The characteristics of transfected cells (SV40-SMC) such as cell growth, collagen and non-collagen syntheses were investigated. SV40-SMC expressed SV40 large T antigen, c-myc and c-myb encoded proteins in the nuclei. SV40-SMC demonstrated a 'hills and valleys'-like arrangement in overconfluence and actin filaments upon immunofluorescent staining. Under electron microscopic observation, SV40-SMC had larger amounts of synthetic organelles and smaller amounts of filament bundles than those of SMC. SV40-SMC demonstrated three times higher growth activity and 4.4 times greater cellular density than SMC. Smooth muscle cells did not grow in media containing 5% plasma derived serum (PDS) instead of normal serum, whereas SV40-SMC proliferated in this medium. SV40-SMC did not grow in soft agar gel, while HeLa S3 cells, a cell line of human cervical carcinoma, formed colonies in this gel. By immunofluorescent (IF) staining, collagen phenotypes I, III, IV and V were detected in both SV40-SMC and SMC. However, protein synthesis including collagen and non-collagen was higher in SV40-SMC than in the control sample. It was concluded that SV40-SMC were a continuous cell line for vascular SMC regarding morphological characteristics, and demonstrated a higher growth activity, with increased collagen and non-collagen syntheses. This cell line is useful for the investigation of atherogenesis in relation to a proliferation of SMC and an accumulation of extracellular matrices in vascular intima.

Agar↗
PubMed1993

The amino acid sequence of neocarzinostatin apoprotein deduced from the base sequence of the gene.

A segment of the neocarzinostatin apoprotein gene corresponding to T30 to A91 of the protein was amplified using a polymerase chain reaction (PCR) with total DNA from Streptomyces carzinostaticus subsp. neocarzinostaticus E-793 (ATCC 15944) as the template and with 5'- and 3'-primers synthesized in consideration of the codon usage of streptomyces. The PCR product was cloned, sequenced and confirmed to direct an amino acid sequence reasonably well matching that reported. Using the PCR product as a probe, we cloned a DNA segment (2580 bp) spanning an open reading frame (ORF) for preapoprotein (leader peptide plus apoprotein) and its upstream and downstream flanking regions. The amino acid sequence deduced from the base sequence of the DNA clearly identified those amino acid residues which had remained inconsistent among different research groups. The base sequence homology with other apoprotein genes of related antibiotics was analyzed and was found to be limited within the structural gene.

Amino Acid Sequence↗
PubMed1993

Iodine 125-phenylpentadecanoic acid and its beta-methyl substitute metabolism in cultured mouse embryonal myocytes--iodine-labelled fatty acids as tracers of myocardial high energy phosphate.

Iodine-labelled fatty acids have been proposed as new tracers of cardiac metabolisms. However, it is not clear how these tracers would reflect the intracellular metabolism. Therefore, we measured the uptake and release of iodine 125-labelled phenylpentadecanoic acid (IPPA), its beta-methyl substitute (BMIPP) and 201Tl in cultured myocytes of mouse embryos, and compared these values to intracellular adenosine triphosphate (ATP) content after metabolic inhibitions of oxidative phosphorylation by sodium cyanide (CN), glycolysis by 2-deoxyglucose (2-DG) or fatty acid beta-oxidation by lactate. The uptake and release of BMIPP was not changed by any inhibitors suggesting BMIPP would not be metabolized in the myocytes. The uptake of IPPA was significantly reduced by 2DG and 60-80% of IPPA was metabolized to hydrophilic catabolites. The correlation of BMIPP and IPPA uptake to intracellular ATP content were high (r = 0.89, p < 0.05; r = 0.86, p < 0.1), but there was poor correlation of 201Tl to ATP values (r = 0.53, n.s.). These results suggested that iodine-labelled fatty acids could be used as better tracers of myocardial metabolism than 201Tl.

Adenosine Triphosphate↗
PubMed1993

[The role of collagen matrix in atherogenesis].

The different types of collagen including Types I, III, IV, V, VI and VIII are distributed in the artery. The atherosclerotic lesions, such as fatty streaks and atheromatous plaques, are characterised by an increase in types V and VI, which are localized in the region with a deposition of LDL and an infiltration of macrophages. Vascular smooth muscle cells interact with various types of collagen. Collagen matrices induce an enhancement of differentiation and suppression of cellular proliferation of "normal" smooth muscle cells. However, transformed smooth muscle cells fail to interact with various types of collagen. These results suggest that the interaction between vascular cells, including smooth muscle cells, macrophages and endothelial cells and collagen matrices is important in atherogenesis.

Adolescent↗
PubMed1992

Studies of the sites of intracellular degradation of apolipoprotein B in Hep G2 cells.

We previously reported that treatment of Hep G2 cells with oleate significantly increased apolipoprotein B (apoB) secretion by reducing early intracellular degradation of nascent apoB. In the current study, inhibitors of secretory protein transport (brefeldin A and monensin), cell fractionation studies, and protease protection assays were utilized to determine the location of apoB degradation and to better define the mechanism whereby oleate treatment reduces nascent apoB intracellular degradation. When cells were treated with brefeldin A, which blocks endoplasmic reticulum (ER) to Golgi protein transport, apoB degradation continued in control cells, suggesting that apoB is degraded in the ER. When oleate-treated cells were blocked with brefeldin A, oleate failed to protect apoB from intracellular degradation. The effects of brefeldin A were not due to effects on lipid synthesis as brefeldin A did not inhibit the synthesis of triglyceride, phospholipid, free cholesterol, or cholesteryl ester in control cells and did not prevent the increases in triglyceride (14-fold) and phospholipid (1.4-fold) synthesis seen in oleate-treated cells. Simultaneous treatment of cells with brefeldin A and nocodazole, which inhibits retrograde transport of proteins from Golgi to ER, added to the evidence for the ER as the site of apoB degradation. This conclusion received further support from experiments in which cells were treated with monensin, a Na+ ionophore which halts protein secretion at the level of the trans-Golgi network. Early degradation of nascent apoB (between 10 and 20 min of chase) was observed in monensin-treated cells, but then cellular apoB degradation ceased and apoB was stable during the remaining chase period. More apoB accumulated in the Golgi of cells that had been treated with oleate and monensin. These results suggest that ER degradation occurs in monensin-treated cells, but then stops as apoB is transferred to the Golgi. The results obtained in whole cells were confirmed in studies using isolated ER and Golgi, which indicated that ER contains a proteolytic activity which degrades apoB, in vitro, whereas Golgi does not. ApoB degradation in isolated ER was not reduced by pretreatment with oleate. Finally, protease protection assays carried out with isolated microsomes indicated that a majority of the apoB in both control or oleate-treated HepG2 cells was located on the cytosolic side of the membranes.(ABSTRACT TRUNCATED AT 400 WORDS)

Albumins↗
PubMed1992

Type V collagen represses the attachment, spread, and growth of porcine vascular smooth muscle cells in vitro.

We attempted to clarify the effects of various purified extracellular components, including types I, III, IV, and V collagen and fibronectin on attachment, spread, growth, and DNA synthesis of porcine aortic smooth muscle cells (SMCs) in vitro. The number, area and shape index (SI = 4 pi S/L2) of cells attached to different substrates were determined at various intervals of incubation. The cell number and [3H]thymidine incorporation into DNA were measured on the 1st and 6th days of culture. SMCs showed the largest number of attached cells on fibronectin, but the smallest number of attached cells on type V collagen. There was no evidence of effects of the serum in media on the attachment of SMCs to the substrates. The areas of attached SMCs were the largest on fibronectin and the smallest on type V collagen. The shape index of SMCs on fibronectin decreased relative to those on other substrates. On the 6th day in culture, the number and population doubling of SMCs on type V collagen were significantly fewer than those on other substrates. Both the incorporation rate of [3H]thymidine into DNA and the percentage of nuclei labeled with [3H]thymidine were significantly less in the SMCs on type V collagen on the 1st day than those on other substrates. SMCs on types I, III, and IV collagen showed intermediate levels of cell attachment, spread, and growth. These results suggest that attachment, spread, and growth of SMCs are affected mainly by solid phase purified extracellular components and are most strongly suppressed by type V collagen. When DNA synthesis of growth-arrested SMCs was reinitiated by the addition of serum, type V collagen most intensively inhibited the rate and amount of [3H]thymidine incorporation. Flow cytometric analysis demonstrated an increased in the proportion of cells in G0/G1 phase on type V collagen in comparison with that on other substrates. Thus, the antiproliferative effect of type V collagen may relate to inhibition of transition of SMCs from the G0/G1 into the S phase.

Animals↗