Biomedical subjects

Y Nagano

Publications and source records attributed to Y Nagano.

At least 19 recordsLinked to original sources

PubMed1992

Yolk vitronectin. Purification and differences from its blood homologue in molecular size, heparin binding, collagen binding, and bound carbohydrate.

This is the first report on a unique vitronectin molecule, yolk vitronectin, which is similar to its blood homologue in cell spreading activity but different in molecular size, bound carbohydrate, and heparin and collagen binding activity. Yolk vitronectin was purified 2,500-fold from chick egg yolk by a combination of hydroxylapatite, DEAE-cellulose, and anti-vitronectin-Sepharose column chromatographies. In SDS-polyacrylamide gel electrophoresis under reducing conditions, yolk vitronectin was separated into 54- and 45-kDa bands, which are 16 and 25 kDa smaller, respectively, than the 70-kDa major band of chick blood vitronectin. The 54-kDa band shares the same NH2-terminal sequence as chick blood vitronectin. In contrast, the NH2-terminal sequence of the 45-kDa band is somewhat homologous with the internal sequences of mammalian vitronectins beginning at the 50th amino acid from the NH2 terminus. The bound carbohydrate of the 54- and 45-kDa species of yolk vitronectin is similar to, but distinct from, that of blood vitronectin. Unlike blood vitronectin, yolk vitronectin cannot bind to either heparin or collagen.

Amino Acid Sequence↗

PubMed1992

Spin-echo M-mode NMR imaging.

A nuclear magnetic resonance (NMR) imaging and display method for the observation of the continuous motion of objects is presented. By modifying a line scan technique, the spin-density distribution along a line is displayed in succession. Although spatial information is limited to only one dimension, the motion of the object is recorded at intervals of 55 ms by using a commercially available NMR imaging system. In a phantom study, this method yielded accurate velocity measurements along a single axis. When the method was applied to the human chest, an image analogous to that of M-mode echocardiography was obtained. This method, which can be called spin-echo M-mode NMR imaging, approaches the functional analysis of cardiac wall motion in regions where echocardiography is not possible. The effects of respiratory motion on the left ventricular wall were recorded in addition to its intrinsic contractile motion in an image obtained along a line parallel to the cranio-caudal axis of the body. The advantages of this method to assess cardiac wall motion in a patient with an arrhythmia were also demonstrated.

Atrial Fibrillation↗

PubMed1992

Probucol and atherosclerosis in the Watanabe heritable hyperlipidemic rabbit--long-term antiatherogenic effect and effects on established plaques.

We performed two studies to investigate the effect of probucol on atherogenesis in vivo in the Watanabe heritable hyperlipidemic (WHHL) rabbit. In the first study (Study A), probucol was administered to 2-month-old WHHL rabbits, to evaluate its long-term effect. When killed at about 1.5 years of age, the percentage area of aorta covered with atherosclerotic plaque in probucol-treated rabbits was markedly less than that seen in non-treated rabbits (23.0 +/- 11.4% vs. 87.7 +/- 8.1%, M +/- S.D., P less than 0.001). In the second study (study B), administration of probucol was commenced with 8-month-old WHHL rabbits to investigate whether the drug was effective for limiting atherosclerosis in rabbits in which plaques had already developed. When killed after 6 months of treatment, the percentage area of aorta covered with plaque was 38.1 +/- 12.1% in treated rabbits and 82.7 +/- 22.6% in non-treated rabbits (P less than 0.02). Microscopic observations of lesions also supported the effect of probucol. Probucol treatment resulted in a change not only in the size but also the composition of lesions. Thus, probucol was effective in preventing atherosclerosis in long-term studies at both early and late stages.

Animals↗

PubMed1992

Decreased arachidonate metabolism in mouse peritoneal macrophages after foam cell transformation with oxidized low-density lipoproteins.

Oxidized low density lipoproteins (LDL) are now considered to be one of the atherogenic lipoproteins in vivo and to play an important role in the pathogenesis of atherosclerosis. We previously demonstrated in mouse peritoneal macrophages that oxidized LDL stimulated prostaglandin (PG) E2 synthesis when incorporated into the cells [Yokode, M. et al. (1988) J. Clin. Invest. 81, 720-729]. In this study, we investigated arachidonate metabolism in macrophages after foam cell transformation. The cells were incubated with 100 micrograms/ml of oxidized LDL for 18 h, then stimulated with zymosan. Lipid-enriched macrophages which had taken up oxidized LDL produced much less eicosanoids, such as PGE2, 6-keto-PGF1 alpha, and leukotriene C4 than control cells. After labeling of the cells with [14C]arachidonic acid, they were stimulated with zymosan and the phospholipase activity was determined. The activity of lipid-enriched cells was about two-thirds of that of control cells. Then we investigated the fatty acid composition of their phospholipid fraction to clarify arachidonic acid content and mobilization. Percent of arachidonic acid of lipid-enriched cells decreased and less arachidonic acid mobilization was observed after stimulation with zymosan. These data suggest that impaired arachidonate metabolism in lipid-enriched macrophages can be explained by their decreased phospholipase activity and changes in their fatty acid composition.

6-Ketoprostaglandin F1 alpha↗

PubMed1992

Probucol pretreatment enhances the chemotaxis of mouse peritoneal macrophages.

To investigate the effects of probucol on macrophage chemotaxis, we preincubated mouse peritoneal macrophages with probucol for 20 hours in vitro and using a modified Boyden chamber system compared their chemotactic responses with those of control macrophages that were preincubated with vehicle. Probucol pretreatment enhanced the macrophage chemotactic responses to zymosan-activated serum, acetylated low density lipoprotein (LDL), and native LDL. Probucol pretreatment also enhanced the basal migration observed when there was no stimulant in the lower chamber of a modified Boyden chamber. The chemoattracting potency of native LDL was weaker than that of zymosan-activated serum in control macrophages; however, both substances became equally potent when the macrophages were preincubated with probucol. The degree of the enhancement to native LDL after probucol preincubation reached fourfold to eightfold. The fashion of the enhanced migration of macrophages to native LDL after preincubation with probucol was predominantly chemotactic rather than chemokinetic. Time-course experiments revealed that it took more than 12 hours of probucol preincubation to show clearly enhanced macrophage chemotaxis to native LDL. Macrophages preincubated with probucol together with cycloheximide showed markedly reduced chemotaxis compared with macrophages preincubated only with probucol. Probucol pretreatment also enhanced macrophage chemotactic responses to high density lipoprotein, oxidized LDL, and lipoprotein-deficient serum.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1992

[A case of acute interstitial nephritis and nonoliguria acute renal failure induced by cimetidine].

Cimetidine is a histamine H2-receptor antagonist. Widely it is prescribed, and then various side effects have been increasingly recognized. Acute renal failure as a result of acute interstitial nephritis is one of the most important adverse effect. We report a case of biopsy-proven acute interstitial nephritis following cimetidine therapy. Farther more, we review other reported cases of cimetidine-induced acute interstitial nephritis, and discuss the clinical features and a role of immunological mechanisms of these cimetidine-induced disorders. A 52-year-old woman was admitted because of fever and protenuria. A month before admission, she developed gastric ulcer and was given cimetidine 600mg orally a day by a near physician. Laboratory data on admission included the following: white blood cell count, 14700/microliters; eosinophils, 6%; BUN, 50.7mg/dl; Cr, 7.6mg/dl; CRP, 34.0mg/dl. All drugs were discontinued because we suspected drug-induced acute renal failure, especially by cimetidine. Renal biopsy performed on day 3 showed interstitial nephritis with lymphocyte infiltration which was composed mainly of T cell. T4/T8 ratio was determined to be 1. There was neither predominance of helper nor cytotoxic cells in T cell subpopulation. We reviewed 22 cases reported and discussed the features of cimetidine-induced interstitial nephritis. The most important thing is to monitor renal function periodically with the suspicion of this disorder. On the detection of abnormality of laboratory data, cimetidine should be discontinued.

Acute Kidney Injury↗

PubMed1992

The role of oxidized lipoproteins in the pathogenesis of atherosclerosis.

1. Oxidized low density lipoprotein (LDL) has been suggested to play an important role in atherogenesis by facilitating the accumulation of lipids in macrophages. In vitro studies from this laboratory have shown that oxidized LDL is recognized not only by the specific receptor for it, but also by the receptor which is common for oxidized LDL and acetyl LDL. Probucol, originally developed as an antioxidant, prevents the oxidative modification of LDL in vitro. Recent studies by the authors show that probucol prevents the progression of atherosclerosis in homozygous Watanabe heritable hyperlipidaemic rabbits in vivo without any changes in plasma LDL cholesterol levels. 2. These results strongly suggest that oxidative modification of LDL could occur in vivo and probucol could slow the progression of atherosclerosis, without changes in plasma cholesterol levels. 3. In addition, recently the authors demonstrated that high density lipoprotein (HDL) particles are also oxidized. Once HDL particles were oxidized, they showed a lessened effect on the decrease of cholesteryl ester in foam cells, suggesting oxidative modification of HDL may stimulate development of atherosclerosis by limiting efflux of cholesterol from foam cells. Moreover, HDL particles from probucol-treated patients are hardly oxidized; subsequently, these HDL particles caused a marked efflux of cholesterol from foam cells.

Animals↗

PubMed1992

[Studies on atherosclerosis with an animal model].

Atherosclerosis is a fundamental cause of life-threatening disorders, such as ischemic heart disease or stroke. Therefore, prevention and treatment of atherosclerosis is a matter of importance. In atherosclerotic lesions, there are many foam cells which contain large amounts of cholesteryl ester. In particular, most of these foam cells in the early stage of atherosclerosis derive from monocytes/macrophages. Today, foam cell transformation of macrophages in subendothelial space is considered to occur by a mechanism in which macrophages take up oxidized low density lipoprotein. We have already discovered that atherosclerosis of Watanabe heritable hyperlipidemic rabbits, an animal model for hereditary hyperlipidemia and severe atherosclerosis, could be prevented by probucol. This drug was originally developed as an antioxidant, and the mechanism of prevention of atherogenesis with this drug is considered that it prevents oxidative modification of LDL. On the other hand, probucol also causes regression of xanthoma in patients with familial hypercholesterolemia. This effect implies that probucol can be effective for treatment of atheromatous lesions, because xanthoma is a lesion which consists of macrophage-derived foam cells. However, the precise mechanism of probucol in causing regression of xanthoma has not been clarified. Considering these observations, we paid special attention to the oxidative modification of high density lipoprotein (HDL). HDL makes contact with foam cells in subendothelial space and stimulates efflux of cholesterol. This is the very place where oxidative modification of LDL is considered to occur. Therefore, it is rational to attempt to determine what would happen when HDL is oxidized and whether probucol could prevent oxidative modification of HDL.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1991

Detection of small GTP-binding proteins in the outer envelope membrane of pea chloroplasts.

We found small GTP-binding proteins in the outer envelope membrane of pea chloroplasts. The proteins in this membrane were separated by SDS-PAGE, transferred to a nitrocellulose filter, and incubated with [alpha-32P]GTP. Three GTP-binding proteins with the molecular weight of 24,000 were found. Binding was prevented by 10(-8)-10(-7) M GTP or by 10(-7) M guanosine 5'-[gamma-thio]triphosphate or GDP; binding was unaffected by 10(-8)-10(-6) M ATP. Thermolysin treatment of intact chloroplasts resulted in the loss of GTP-binding activity, suggesting that these proteins were in the cytosolic side of the outer envelope membrane.

Binding, Competitive↗

PubMed1991

High density lipoprotein loses its effect to stimulate efflux of cholesterol from foam cells after oxidative modification.

In this study, we performed oxidative modification of high density lipoprotein (HDL) in vitro. The amount of lipid peroxide increased when either HDL2 or HDL3 was incubated with phosphate-buffered saline containing 5 microM CuSO4 for 24 h at 37 degrees C, indicating that both fractions of HDL were oxidatively modified. This modification resulted in denaturation of apolipoprotein AI on SDS/PAGE and increased the negative charge on agarose gel electrophoresis. When incubated with macrophage-derived foam cells, native HDL caused a marked efflux of cholesterol from them, leading to a decrease in the amount of cholesteryl ester in the cells. However, oxidized HDL showed a lessened effect on the decrease of cholesteryl ester in foam cells. These data suggest that oxidative modification of HDL may stimulate development of atherosclerosis by limiting efflux of cholesterol from foam cells.

Animals↗

PubMed1991

Nucleotide sequence and expression of the ribosomal protein L2 gene in pea chloroplasts.

We sequenced the nucleotides around the rpl2 gene, encoding the ribosomal protein L2, in pea (Pisum sativum cv. Alaska) chloroplasts and analyzed the expression of the rpl2 gene. During deetiolation, accumulation of the rpl2 transcript did not require de novo protein synthesis on chloroplastic ribosomes, in contrast to that of most chloroplast-encoded genes. This suggested that the mechanism involved in the expression of rpl2 differed from that of most chloroplast-encoded genes.

Amino Acid Sequence↗

PubMed1991

An essential gene of Escherichia coli that has sequence similarity to a chloroplast gene of unknown function.

The dedB gene of Escherichia coli has sequence similarity to the zfpA gene of the chloroplast chromosome. The functions of dedB and zfpA are unknown. We constructed derivatives of temperature-sensitive polA strains into whose chromosomes a plasmid containing the disrupted dedB gene was integrated by homologous recombination. These strains contained normal and disrupted dedB genes in their chromosomes. We then selected plasmid-segregated strains and found no cells containing the disrupted dedB gene, indicating that disruption of the dedB gene was lethal in polA strains of E. coli.

Blotting, Southern↗

PubMed1991

Sequence and transcriptional analysis of the gene cluster trnQ-zfpA-psaI-ORF231-petA in pea chloroplasts.

A 5.1 kb segment of pea chloroplast DNA containing the upstream region of petA was sequenced. RNAs produced from this DNA were characterized. This region encodes putative genes for psbK, trnQ, zfpA, psaI, ORF231, and petA. These genes are all on the same reading strand except for psbK. The gene organization is somewhat different from that of tobacco, rice, and liverwort, which lack the psbK-trnQ genes in this region and contain ORF184/185. Northern blot and primer extension analysis show that the pea transcript covers the zfpA-psaI-ORF231-petA gene cluster and trnQ. These results indicated that the psbK-trnQ genes have been rearranged and a new transcription unit was formed.

Amino Acid Sequence↗

PubMed1991

Restriction endonuclease digest patterns of chromosomal DNA from group B beta-haemolytic streptococci.

Scanning densitometry and computer-assisted numerical analysis were used to examine restriction endonuclease digest patterns (RDPs) of chromosomal DNA from 26 infecting strains and 44 vaginal isolates of group B beta-haemolytic streptococci (GBS). At the 95% similarity level, HindIII RDPs of serotype Ia and III strains clustered into four and three RDP types, respectively. Nine of 10 strains from neonates with early-onset septicaemia belonged to two particular RDP types (Ia-3 and III-3). In contrast, serotype III GBS strains from meningitis cases were not characterised by particular RDP types. Associations between RDPs and certain phenotypic characteristics were also found.

Chromosomes, Bacterial↗

PubMed1991

Effects of the methylprednisolone pulse therapy on renal function.

The effect of the methylprednisolone (MP) pulse therapy on renal function was examined in 15 patients with renal or collagen disease. Three nephrotic patients who had reduced renal function and active renal disease with progressive deterioration of renal function prior to the use of MP developed transient renal failure following an MP pulse therapy. The renal failure in each case was reversed by discontinuation of MP and/or by forced diuresis using albumin and furosemide. We examined the correlations between the individual changes in serum creatinine (Scr), body weight (BW) and urine volume (UV) before and after the pulse therapy and other laboratory data such as Scr, total serum protein and albumin. There were significant correlations between a change in Scr on the one hand and changes in BW and UV, Scr and serum albumin on the other. These findings mean that the effect of the MP pulse therapy on renal function depends on the clinical state of the patient and that renal deterioration after the pulse therapy may be more marked in patients who are more nephrotic and more impaired in renal function and suggest that increasing sodium and water retention during an MP therapy and the associated renal interstitial edema, proposed as one of the mechanisms of acute renal failure occurring in patients with minimal-change nephrotic syndrome, may be responsible for the MP-induced transient renal failure.

Acute Kidney Injury↗

PubMed1991

Rational design and synthesis of a novel class of active site-targeted HIV protease inhibitors containing a hydroxymethylcarbonyl isostere. Use of phenylnorstatine or allophenylnorstatine as a transition-state mimic.

A novel class of HIV-1 protease inhibitors containing a hydroxymethylcarbonyl (HMC) isostere were designed from the substrate transition state and synthesized. Phenylnorstatine [Pns; (2R,3S)-3-amino-2-hydroxy-4-phenylbutyric acid] and the 2S diastereomer, (2S,3S)-3-amino-2-hydroxy-4-phenylbutyric acid, named allophenylnorstatine (Apns) were effective transition-state mimics, and incorporation of Pns-Pro or Apns-Pro at the P1-P1' site gave potent and specific HIV-1 protease inhibitors. In the inhibitory assays, the chemically synthesized [Ala67,95] HIV-1 protease was used.

Amino Acid Sequence↗

PubMed1991

[Cytoplasmic staining pattern characteristic for anti Jo-1 antibody in HEp-2 cells].

We wished to confirm the staining pattern of HEp-2 cells by the anti Jo-1 antibody, because we found antibodies in serum with positive anti Jo-1 antibody which showed either a fibrilar cytoplasmic staining or a nuclear speckled staining pattern in indirect immuno fluorescence+ examinations using HEp-2 cells. Sera available from eight patients with PM DM (polymyositis and/or dermatomyositis) showed positive anti Jo-1 antibody in the double immuno-diffusion technique but had various staining patterns of HEp-2 cells in the immunofluorescent examination. We examined these eight sera with the immuno-blotting method utilizing whole cell extract of HeLa cells, and found the 50 kDa band from all sera tested, to which Jo-1 antigen had been reported to move. We eluted the antibody which formed the 50 kDa band from the nitrocellulose membrane and applied it on HEp-2 cells. This maneuver gave us the fine granular cytoplasmic staining of anti Jo-1 antibody on HEp-2 cells. We therefore concluded that the anti Jo-1 antibody should have cytoplasmic staining on HEp-2 cells although observers might miss it due to other types of associated antinuclear antibodies.

Antibodies, Antinuclear↗

PubMed1991

Interaction of sodium and potassium ions with Na+,K(+)-ATPase. IV. Affinity change for K+ and Na+ of Na+,K(+)-ATPase in the cycle of the ATP hydrolysis reaction.

The Kd for ouabain-sensitive K+ or Rb+ binding to Na+,K(+)-ATPase was determined by the centrifugation method with radioactive K+ and Rb+ in the presence of various combinations of Na+, ATP, adenylylimidodiphosphate (AMPPNP), adenylyl-(beta,gamma-methylene)diphosphonate (AMPPCP), Pi, and Mg2+. From the results of the K+ binding experiments, Kd for Na+ was estimated by using an equation describing the competitive inhibition between the K+ and Na+ binding. 1) The Kd for K+ binding was 1.9 microM when no ligand was present. Addition of 2 mM Mg2+ increased the Kd to 15-17 microM. In the presence of 2 mM Mg2+, addition of 3 mM AMPPCP with or without 3 mM Na+ increased the Kd to 1,000 or 26 microM, respectively. These Kds correspond to those for K+ of Na.E1.AMPPCPMg or E1.AMPPCPMg, respectively. 2) Addition of 4 mM ATP with or without 3 mM Na+ decreased the Kd from 15-17 microM to 5 or 0.8 microM, respectively. Because the phosphorylated intermediate was observed but ATPase activity was scarcely observed in the K+ binding medium containing 3 mM ATP and 2 mM Mg2+ in the absence of Na+ as well as in the presence of Na+ at 0 degrees C, it is suggested that K+ binds to E2-P.Mg under these ligand conditions. 3) The Kd for Na+ of the enzyme in the presence of 3 mM AMPPCP or 4 mM ATP with Mg2+ was estimated to be 80 or 570 microM, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine Triphosphate↗