Biomedical subjects

S Ando

Publications and source records attributed to S Ando.

At least 289 records · Page 16Linked to original sources

PubMed1991

Characterization of lipoprotein secreted by cultured eel hepatocytes and its comparison with serum lipoproteins.

The lipoprotein secreted by cultured eel hepatocytes was fractionated by density gradient ultracentrifugation and compared with eel serum lipoproteins. Eel hepatocytes were cultured for 7 to 10 days as a monolayer in Williams' medium E containing 5% fetal bovine serum and 0.16 microM insulin on a dish precoated with fibronectin of horse serum. The only lipoprotein secreted by eel hepatocytes was a very-low-density lipoprotein like one which consisted of 69% triglyceride, 15% phospholipid, 4% cholesterol, and 12% protein. On the other hand, very-low-density lipoprotein and high density lipoprotein were found in eel serum, in which high density lipoprotein was a main lipoprotein. The secreted lipoprotein contained apo B and apo A as the main protein components. Furthermore, the lipoprotein contained proapo A-I in addition to apo A-I, which was proved by comparing the amino acid composition of both proteins. In our discussion, we noted that the lipoprotein secreted by eel hepatocytes was a good material for the study of high-density lipoprotein formation.

Amino Acids↗

PubMed1991

Kinetic studies on the appearance of antigens of Chlamydia psittaci during its developmental cycle.

The kinetics of the antigen production of Chlamydia psittaci strains Izawa-1 and Pigeon-1041 (P-1041) was examined every 6 hr after infection up to 48 hr, by the indirect immunofluorescent antibody technique using monoclonal antibodies (MAbs). All three genus-specific antigenic determinants on lipopolysaccharide (LPS) appeared during the whole growth cycle. Antigenic determinants on proteins were, on the other hand, detected at various time periods from the early to the late stages of infection. However, a cross-reactive antigenic determinant on protein recognized by a MAb 3E9 was also detected during the whole growth cycle, similar to that on LPS. The time of appearance of common antigenic determinants on proteins of Izawa-1 and P-1041 was examined using cross-reactive MAbs, and it varied depending on heterologous and homologous MAbs. From the relationship between the detection of antigenic determinants and the morphological changes of chlamydial particles revealed by electron microscopy during the growth cycle, the antigenic determinants on proteins of Chlamydia psittaci were divided into two groups; one was specific to the elementary body and the other was coexisting in both the elementary body and the reticulate body.

Animals↗

PubMed1991

Clinical characteristics of patients with dilated cardiomyopathy and bradyarrhythmias.

The clinical characteristics of patients with dilated cardiomyopathy and bradyarrhythmias were studied. Among 50 patients with dilated cardiomyopathy, 6 had bradyarrhythmias. Among these patients were one with sinus bradycardia, one with atrial fibrillation and slow ventricular responses and sick sinus syndrome (SSS), one with SSS with advanced AV block, and 3 with advanced AV block. The average age at the onset of their cardiac symptoms (60.3 +/- 12.1 years (mean +/- SD)) was significantly (p less than 0.01) higher than that of 43 patients without bradyarrhythmias (40.0 +/- 17.6). The left ventricular diastolic dimension and ejection fraction were similar among patients with and without bradyarrhythmias. In 31 follow-up patients without bradyarrhythmias, 8 (25.8%) died of cardiac causes; whereas, in 5 patients with bradyarrhythmias, 4 had been implanted with pacemakers and 3 (60.0%) died of cardiac causes. Furthermore, the age at the onset of cardiac symptoms in patients with any kind of conduction disturbance, except tachyarrhythmia, was 50.4 +/- 16.5 years (n = 25), which was significantly higher (p less than 0.02) than that of patients without conduction disturbances (37.7 +/- 19.3 years, n = 23). We concluded that bradyarrhythmias are not rare complications in patients with dilated cardiomyopathy, and the mortality rate tends to be higher in patients with bradyarrhythmias than in those without them. Furthermore, the risks of conduction disturbances and bradyarrhythmias were higher in the elderly patients.

Adult↗

PubMed1990

Effect of isolated C-terminal fragment of theta-toxin (perfringolysin O) on toxin assembly and membrane lysis.

theta-toxin, a thiol-activated cytolysin, binds cholesterol and assembles on plasma membrane during the lytic process. In order to understand the process at the molecular level, two fragments (T1 and T2) were isolated from a nicked toxin obtained by limited proteolysis with trypsin. Although neither the T1 nor T2 fragment has hemolytic activity. T2 has almost the same potential as native theta-toxin in its binding affinity for erythrocytes and in its binding specificity for cholesterol. T2, derived from the C-terminus of the toxin, loses binding activity upon 5,5'-dithiobis(2-nitrobenzoic acid) modification of the thiol group. The T2 fragment was found to abolish the hemolytic activity of theta-toxin completely without any inhibition of theta-toxin binding to erythrocytes. theta-toxin normally appears in polymeric form on membranes, while it remains in monomer form in the presence of the T2 fragment, as judged by sedimentation patterns in sucrose density-gradient centrifugation. These results indicate that without inhibiting binding, the T2 fragment inhibits hemolysis by preventing theta-toxin from aggregating on membranes, a step that might be essential for the lytic process.

Animals↗

PubMed1990

Age-related changes in the uptake of calcium channel blockers by brain capillary endothelial cells and synaptosomal fractions.

The effects of aging on the uptake of calcium channel blockers through brain capillaries to brain parenchyma were investigated. Two different piperazine derivatives, flunarizine and 1-[bis(fluorophenyl)-methyl]-4-(2,3,4-trimethoxybenzyl)piperazine (abbreviated as KB-2796), were orally administered to young and aged rats. The concentrations of the blockers in plasma, endothelial cells of the brain capillaries and synaptosomal fractions of the three brain regions were determined by high-performance liquid chromatography. Flunarizine was more incorporated into brain tissues than KB-2796 in both young and aged rats. The uptake efficiency of KB-2796 from the circulation to the brain decreased more remarkably than that of flunarizine in aged rats. The partition coefficients between n-octanol and water indicated that KB-2796 was less hydrophobic than flunarizine. These results suggest that the uptake of the chemicals seems to be influenced by their hydrophobicity and the age of animals given.

Aging↗

PubMed1990

Insect lipid transfer particle catalyzes bidirectional vectorial transfer of diacylglycerol from lipophorin to human low density lipoprotein.

Insect plasma lipid transfer particle (LTP) catalyzes vectorial net transfer of diacylglycerol (DAG) from Manduca sexta larval high density lipophorin (HDLp-L) to human low density lipoprotein (LDL) producing an LDL of lower density and lipophorin subspecies of higher density. At equilibrium, a stable DAG-depleted very high density lipophorin species (density = 1.25 g/ml) is formed. Electrophoretic analysis of the substrate and product lipoproteins showed that apoprotein exchange or transfer between human LDL and lipophorin did not occur during the lipid transfer reaction. Facilitated net transfer of cholesteryl ester, free cholesterol, and phospholipid occurred to a much lower extent than DAG net transfer, indicating that under these conditions, LDL serves as a sink for lipophorin-associated DAG. This reaction, therefore, provides a method whereby the mass of lipid associated with human LDL can be modified in vitro without alteration of its apoprotein component. The DAG content of LDL increased in a linear manner with respect to LTP concentration and time during the initial phase of the reaction, demonstrating the utility of this system as a quantitative assay method for LTP-mediated net DAG transfer. When [3H]DAG-labeled LDL was prepared and employed in transfer experiments with unlabeled lipophorin, labeled DAG was recovered in the HDLp-L fraction. The amount of labeled DAG recovered in the HDLp-L fraction was dependent on the ratio of LDL to HDLp-L in the reaction. Thus, in this system, LTP-mediated DAG redistribution is bidirectional, suggesting that the final equilibrium distribution of lipid may be dictated by the properties of potential donor/acceptor lipoproteins rather than by an inherent particle substrate specificity of LTP.

Animals↗

PubMed1990

Growth of rat-mouse hybridoma cells in immunosuppressed hamsters. An easy and effective method to prepare monoclonal antibodies from heterohybridoma cell lines.

Rat-mouse hybridoma cells producing anti-mouse IgE antibodies were intraperitoneally or subcutaneously inoculated into newborn or suckling hamsters receiving rabbit anti-hamster thymocyte globulin from the day of birth twice a week for at least 3 weeks. The hybridoma cells were found to grow in the abdominal cavity of the hamsters as ascites tumor or in subcutaneous tissue as solid tumor without loss of antibody-secreting activities. For the production of ascites, 2-week-old hamsters were preferable to newborn hamsters. In 3-week-old hamsters, the hybridoma cells could scarcely survive. The antibody titers of the ascites were determined to be 10(5)-10(6) in the ELISA and in the ability to neutralize the skin-sensitizing capacity of mouse IgE antibodies. The rat monoclonal antibodies were easily separated from ascites, serum or cell culture supernatant with affinity chromatography using Affigel protein A-Sepharose and anti-hamster IgG-Sepharose columns. The described method could be efficiently applicable for the proliferation of other hybridomas, such as human-human, human-mouse or hamster-mouse, etc.

Animals↗

PubMed1990

Increased levels of lipid peroxides in aged rat brain as revealed by direct assay of peroxide values.

Lipid peroxide concentrations in brain tissues of young and aged rats were determined by a direct method for measuring peroxide values. Three different brain regions were analyzed for lipid peroxides. The peroxide levels increased in all three regions of aged as compared to those of young rats, while lipid peroxides in plasma appeared to be stable along with age. Lipid peroxides in cerebrum and cerebellum increased 1.6-2.0 times in aged brains compared with young ones, and about 3-fold in the brain stem. Increased levels of lipid peroxides in aged brains seem not merely due to increased pools of precursor polyene fatty acids, but rather due to altered protection systems for lipid peroxidase formation.

Aging↗

PubMed1990

Isolation and characterization of extremely minor gangliosides, GM1b and GD1 alpha, in adult bovine brains as developmentally regulated antigens.

In addition to ganglioside GM1b, an unusual and extremely minor ganglioside, GD1 alpha, was efficiently isolated from bovine brain by combination of Q-Sepharose and Iatrobeads column chromatographies. In the course of purification steps, the presence of the sialidase-labile ganglioside was proved by a highly sensitive TLC/enzyme-immunostaining method. The structure was characterized by gas-liquid chromatography, permethylation study, sialidase degradation, immunostaining with specific antibodies, fast atom bombardment-mass spectrometry, and proton magnetic resonance spectrometry. The content of the ganglioside was very small (0.016%) in the total gangliosides. This finding suggests that a synthetic pathway of asialo GM1----GM1b----GD1 alpha may exist in mammalian brains. A monoclonal antibody NA-6 that was obtained by immunizing mice with purified GM1b reacted specifically with GM1b but showed no cross-reactivity with other structurally related gangliosides such as GM1a, GD1a, and so on. Using the method of TLC/immunostaining with NA-6, GM1b was found to be strongly expressed during embryonic days 14-17 in chick brains. Thus, it is assumed that extremely minor gangliosides like GM1b and GD1 alpha found in adult brains are characterized as embryonic molecules.

Animals↗

PubMed1990

Clinical evaluation of a newly developed enteric nutrient given to the neurosurgical patients with disturbances of consciousness.

An enteric nutrient 'SAN-ET-A', rich in protein and electrolytes, was given to 8 patients with disturbances of consciousness. Although the adminstered dosage had a calorie content so low that basal metabolism was barely maintained, the level of serous proteins increased following administration. Electrolyte imbalance was not found, and the patients did not suffer from severe renal or liver dysfunctions. No notable gastrointestinal troubles occurred except in one case. It is concluded that a low dosage of SAN-ET-A was sufficient to maintain the patients in good nutritional condition. Furthermore, it is suggested that this nutrient can be safely given for a long period.

Aged↗

PubMed1990

A modified theta-toxin produced by limited proteolysis and methylation: a probe for the functional study of membrane cholesterol.

A derivative of cytolytic theta-toxin from Clostridium perfringens was prepared by limited proteolytic digestion of the native toxin followed by methylation. Among the chloroform/methanol-extractable, lipid components of sheep and human erythrocytes, the proteinase-nicked and methylated derivative (MC theta) specifically binds to cholesterol. While MC theta retains binding affinity comparable to that of intact toxin, it causes no obvious membrane damage, resulting in no hemolysis at temperatures of 37 degrees C or lower. Using MC theta, we demonstrated the possible existence of high- and low-affinity sites for theta-toxin on sheep erythrocytes at both 37 degrees C and 10 degrees C. The number of high-affinity sites on sheep erythrocytes was estimated to be approximately 3-times larger at 37 degrees C than that at 10 degrees C. In addition, high- and low-affinity sites were demonstrated in human erythrocytes and a lymphoma B cell line, BALL-1 cells. Both binding sites disappear upon simultaneous treatment of cells with sublytic doses of digitonin, suggesting that cholesterol is an essential component of both the high- and low-affinity sites and that the mode of cholesterol existence in plasma membranes is heterogeneous in these cells. Because of its high affinity for membrane cholesterol without causing any obvious membrane changes at physiological temperatures, MC theta may provide a probe for use in the functional study of membrane cholesterol.

Animals↗

PubMed1990

Lipid transfer between human plasma low-density lipoprotein and a triolein/phospholipid microemulsion catalyzed by insect hemolymph lipid transfer particle.

Lipid transfer between human plasma low-density lipoprotein (LDL) and an LDL-size microemulsion of triolein and phosphatidylcholine stabilized with human apolipoprotein A-I was catalyzed by the lipid transfer particle from hemolymph of the tobacco hornworm (Manduca sexta). Net transfer of phospholipid and triacylglycerol from the emulsion to LDL was observed and the apparent initial rates of transfer were dependent on the amount of catalyst. Net transfer of phospholipid mass was twice as much as that of triacylglycerol with respect to both the initial rate and the final equilibrium state. The final amount of net transfer of both lipids was dependent upon the initial ratio of LDL: microemulsion present in the incubation mixture up to 1:1 on the basis of phospholipid. The microemulsion lipid composition was maximally altered from an initial weight ratio of 1.09 +/- 0.08 (phospholipid/triolein) to 0.90 +/- 0.03 by this reaction. Further increase of LDL in the incubation caused neither further net transfer nor further change in the lipid composition of the microemulsion. The catalyst neither affected spontaneous transfer of free cholesterol between the emulsion and LDL nor enhanced cholesteryl ester transfer in this reaction system. As a result of the facilitated reaction, LDL gained a significant amount of phospholipid and triacylglycerol causing up to an 8% increase in core lipids and 14% in phospholipid. Some free cholesterol is recovered in the emulsions via spontaneous exchange. Transfer or exchange of apolipoproteins during the course of facilitated lipid transfer did not occur.

Animals↗

PubMed1990

Involvement of protein kinase C in the regulation of assembly-disassembly of neurofilaments in vitro.

Protein kinase C phosphorylated the major mammalian neurofilament protein (NF-L) with approximately 3 mol phosphate per mol protein. The phosphorylated NF-L no longer formed the filaments. Sequential analysis of the tryptic phosphopeptides, together with the known primary sequence, revealed that Ser-12, Ser-27, Ser-33 and Ser-51 were phosphorylated by protein kinase C. These findings contribute toward elucidation of mechanisms regulating the functions of neurofilaments.

Amino Acid Sequence↗

PubMed1990

Phosphorylation sites linked to glial filament disassembly in vitro locate in a non-alpha-helical head domain.

Glial fibrillary acidic protein (GFAP), the intermediate filament component of astroglial cells, can serve as an excellent substrate for both cAMP-dependent protein kinase and protein kinase C, in vitro. GFAP phosphorylated by each protein kinase does not polymerize, and the filaments that do polymerize tend to depolymerize after phosphorylation. Dephosphorylation of phospho-GFAP by phosphatase led to a recovery of the polymerization competence of GFAP. Most of the phosphorylation sites for cAMP-dependent protein kinase and protein kinase C on GFAP are the same, Ser-8, Ser-13, and Ser-34. cAMP-dependent protein kinase has one additional phosphorylation site, Thr-7. All the sites are located within the amino-terminal non-alpha-helical head domain of GFAP. These observations pave the way for in vivo studies on organization of glial filaments.

Animals↗

PubMed1990

Synaptic aging as revealed by changes in membrane potential and decreased activity of Na+,K(+)-ATPase.

Age-related changes in the membrane potential of nerve terminals were investigated by monitoring the accumulation of tritium-labeled triphenylmethylphosphonium ion, [3H]TPMP+, in mouse cortical synaptosomes. The resting membrane potential became less negative with advancing age, that is, it changed from -64.5 +/- 0.8 to -58.1 +/- 2.3 mV between 6 and 27 months of age. The intrasynaptosomal potassium concentration was found to decrease concomitantly by 13% in aged mice (56.6 +/- 0.9 mM) as compared to young-adult mice (64.9 +/- 0.5 mM). The ouabain-sensitive Na+,K(+)-ATPase activity of synaptic plasma membranes decreased in late senescence to 82% of the adult level. To examine the correlation with the decreased Na+,K(+)-ATPase activity, the membrane lipid composition was analyzed. Among the membrane phospholipids, only the content of phosphatidylcholine decreased in the course of senescence. The changes in the Na+,K(+)-ATPase activity were found to be positively correlated with the changes in the phospholipid content, and more specifically with the changes in the phosphatidyl-choline content. These results suggest that age-related alterations in the microenvironment constructed by phospholipids may decrease the activity of Na+,K+-ATPase, resulting in neuronal ion imbalance and decreased membrane potential. This might be responsible in part for altered functions of nerve terminals in aging brain.

Aging↗

PubMed1990

Differences in lipid composition between isolated growth cones from the forebrain and those from the brainstem in the fetal rat.

The lipid composition of nerve growth cone membranes isolated from rat fetal forebrain or brainstem by the sucrose density gradient method was analyzed biochemically and immunochemically. In the forebrain, growth cone membrane (GCM) contained lower levels of gangliosides than those from other heavier fractions, but it was not the case in the fetal brainstem at the same developmental stage. The distinctive features in the ganglioside composition of GCM are the predominance of GD3 and the presence of c-series gangliosides that are due to fetal expression in mammals. A unique acidic glycolipid, sulfoglucuronylparagloboside (SGPG), which is not present in adult brains, was first detected in both forebrain and brainstem GCM. Including such minor species, the ganglioside composition in forebrain or brainstem GCM was almost identical to other membrane fractions from the forebrain or brainstem. The compositional ratios of the major lipid classes in membranes, cholesterol and phospholipids, seemed to be common to forebrain GCM and brainstem GCM, as indicated by the identical values of phospholipid-to-protein (PL/Pr), cholesterol-to-protein (Ch/Pr), and cholesterol-to-phospholipid (Ch/PL) ratios for both. This study has revealed that GCM isolated from forebrain which is supposed to be at an earlier stage of neuronal differentiation than brainstem has less amounts of total gangliosides, high proportion of GD3 to GD1a and enriched c-series gangliosides as compared to brainstem GCM.

Animals↗

PubMed1990

Human G-CSF produced by adherent cells in the presence of human recombinant GM-CSF.

Adherent cells (AdCs) in blood from normal volunteers produced granulocyte-macrophage (GM) colony-stimulating activity (CSA) in the presence of 10 ng/ml of recombinant human granulocyte-macrophage colony-stimulating factor (rhGM-CSF) in vitro. GM-CSA produced by adherent cells in the presence of GM-CSF reached a plateau level on day 6. Colonies stimulated by adherent cell-conditioned medium (AdC-CM-GM-CSF), which had been harvested after 6 days of incubation of AdCs with rhGM-CSF, were granulocyte predominant. When phagocyte-depleted marrow mononuclear cells (PD-M-MNCs) were cultured with AdC-CM-GM-CSF and anti-rabbit serum against rhGM-CSF, 99% of the colonies on day 7 were exclusively composed of neutrophils. When 2 X 10(4) PD-M-MNCs were cultured in a medium containing AdC-CM-GM-CSF, AdC-CM-GM-CSF + anti-GM-CSF, AdC-CM-GM-CSF + anti-G-CSF, or AdC-CM-GM-CSF + both of the anti-bodies, the PD-M-MNCs formed (mean +/- SD) 100 +/- 2.0%, 64.3 +/- 2.5%, 38.6 +/- 0.4%, and 6.0 +/- 0.4% GM colonies, respectively. Furthermore, northern blot analysis revealed that AdCs incubated with 10 ng/ml of rhGM-CSF for 6 h expressed much more mRNA of G-CSF than those without the CSF. These data indicated that AdCs in blood produce G-CSF in the presence of GM-CSF.

Blotting, Northern↗

PubMed1990

Different effects of alpha-human atrial natriuretic peptide and nitroglycerin on cardiac dimensions in humans.

This study aimed to examine whether alpha-human atrial natriuretic peptide (alpha-hANP) alters cardiac dimensions in humans. Left atrial (LA) and left ventricular diastolic (LV) diameters were measured by echocardiography at control and with lower body negative pressure (LBNP) at -10 and -20 mmHg during intravenous (IV) infusion of saline or alpha-hANP at a dose of 0.03-0.04 microgram/kg per minute (n = 8). Studies were also done during IV infusion of saline or nitroglycerin (NG) at a dose of 10-15 micrograms/kg per minute in another group of subjects (n = 6). LBNP decreased central venous pressure (CVP) and the LA and LV diameter. alpha-hANP lowered CVP at rest and with LBNP at -10 and -20 mmHg compared with corresponding values during saline infusion; NG produced comparable decreases in CVP, which suggests that decreases in venous return caused by the two drugs were similar. However, NG decreased, but alpha-hANP did not alter the LA and LV diameter at rest or with LBNP. In another group of subjects (n = 4), we observed that alpha-hANP caused comparable decreases in CVP and pulmonary capillary wedge pressure. These data suggest that ANP may dilate the cardiac chambers in humans.

Adult↗