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Biomedical subjects

Y Nagano

Publications and source records attributed to Y Nagano.

At least 73 records · Page 4Linked to original sources
PubMed1996

Oxygen intake efficiency slope: a new index of cardiorespiratory functional reserve derived from the relationship between oxygen consumption and minute ventilation during incremental exercise.

We investigated the usefulness of the oxygen intake efficiency slope (OIES) as a submaximal measure of cardiorespiratory functional reserve. OIES was derived from the relationship between oxygen consumption (VO2; ml/min) and minute ventilation (VE; l/min) during incremental exercise, which was determined by the following equation: VO2 = a logVE + b, where "a" represents OIES, which shows the effectiveness of ventilation. Maximal oxygen consumption (VO2max) is effort-dependent. There is no standard submaximal measurement of cardiorespiratory reserve that provides generally acceptable results. Exercise tests were performed by 17 normal volunteers on an ergometer using a symptom-limited Ramp protocol. Expired gas was continuously analyzed. OIES was calculated using the first 75%, 90%, and 100% of exercise data. We also determined the following submaximal parameters: the ventilatory anaerobic threshold (VAT), the slope of the minute ventilation-carbon dioxide production relationship (VE-VCO2 slope), and the extrapolated maximal oxygen consumption (EMOC). We analyzed the relationship between OIES, other submaximal parameters and VO2max, and examined the effects of submaximal exercise on OIES. The correlation coefficient of the logarithmic curve-fitting model was 0.991 +/- 0.006. OIES and VO2max were significantly correlated (r = 0.966, p < 0.0001). The correlation between OIES and VO2max was stronger than the correlation between VO2max and VAT, the VE-VCO2 slope and EMOC. OIES values for 100% and 90% of exercise were identical; OIES for 75% of exercise was slightly lower (3%). Our results suggested that OIES may provide an objective, effort-independent estimation of cardiorespiratory functional reserve.

Adolescent↗
PubMed1995

Location of light-repressible, small GTP-binding protein of the YPT/rab family in the growing zone of etiolated pea stems.

YPT/rab proteins are ras-like small GTP-binding proteins that serve as key regulators of vesicular transport. The mRNA levels of two YPT/rab genes in pea plants are repressed by light, with the process mediated by phytochrome. Here, we examined the mRNA expression and the location of the two proteins, pra2- and pra3-encoded proteins, using monoclonal antibodies. The pra2 and pra3 mRNA levels were highest in the stems of dark-grown seedlings. The corresponding proteins were found in the cytosol and the membranes of the stems. Most of the pra2 protein was in the growing internodes, especially in the growing region, but the pra3 protein was widespread. These results suggest that the pra2 protein is important for vesicular transport in stems, possibly contributing to stem growth in the dark, and that the pra3 protein is important for general vesicular transport. The amounts of pra2 and pra3 proteins decreased with illumination. The decrease in these proteins may be related to the phytochrome-dependent inhibition of stem growth that occurs in etiolated pea seedlings.

Animals↗
PubMed1995

Role of C5a-ase in group B streptococcal resistance to opsonophagocytic killing.

Type III group B streptococci (GBS) can be subdivided into three subtypes, RDP III-1, III-2, and III-3, on the basis of numerical analysis of HindIII restriction endonuclease digestion patterns (HindIII RDP) with their chromosomal DNAs. In the present study, the effect of C5a on opsonophagocytic killing of a representative strain from each RDP type was investigated by using a novel optical method for determining opsonophagocytic killing, and the effect of C5a-ase treatment of C5a on opsonophagocytic killing was also investigated. Pre-stimulation of polymorphonuclear leukocytes (PMNs) with C5a significantly increased opsonophagocytic killing of all three strains. The increase in killing was abolished by pretreating the C5a with GBS that express C5a-ase, a treatment that also destroyed the chemoattractant activity of the C5a. The kinetics of killing of the RDP III-2 strain differed from those of the other two strains. The survival of the RDP III-2 bacteria continued to decline over the entire 60-min incubation of the opsonophagocytic assay when PMNs were prestimulated with C5a or with C5a that had been inactivated with GBS C5a-ase (dC5a). In contrast, killing of the RDP III-1 and III-3 strains almost ceased after 20 or 60 min when PMNs were prestimulated with dC5a or C5a, respectively. A difference in bacterial killing between the III-2 strain and the III-1 and III-3 strains therefore became increasingly apparent with prolonged incubation time. The percentage of bacteria surviving in the extracellular fluid was approximately the same as the percentages of bacteria surviving in both intracellular and extracellular locations when PMNs were prestimulated with either C5a or dC5a. These data imply that the majority of bacterial killing occurred following phagocytosis and suggest that the enhanced killing of GBS following prestimulation of PMNs with C5a resulted from increased ingestion of the bacteria.

Adhesins, Bacterial↗
PubMed1994

Studies on FGF-2: nuclear localization and function of high molecular weight forms and receptor binding in the absence of heparin.

Multiple forms of FGF-2 have been shown to exist in many cell types. These different species of molecular masses of 18, 21.5, 22, and 24 kDa are all translated via the use of alternate initiation codons. The three forms of HMW FGF-2 initiate at CUGs codons, whereas the 18 kDa form initiates at an AUG codon. The entire 18 kDa sequence is contained within the larger forms of HMW FGF-2 as the AUG codon is 3' to the CUG codons. Although the 18 kDa form FGF-2 is localized primarily in the cytosol, a significant fraction of the HMW FGF-2 has a nuclear location. The nuclear localization of HMW FGF-2 is determined by amino acid residues in the amino-terminal extended sequence. The residues required for nuclear localization appear to be RG repeats that are found at multiple sites within the amino-terminal extension of HMW FGF-2. The nuclear localization of HMW FGF-2 suggested that these species may have unique properties. By selecting permanent transfectants of 3T3 cells expressing HMW, 18 kDa FGF-2, or all forms of FGF-2, we have found that HMW FGF-2 can endow cells with a phenotype different from that of cells expressing 18 kDa FGF-2. These cells are transformed by what appears to be the intracellular action of HMW FGF-2. The interaction of FGF-2 with heparin has also been examined.(ABSTRACT TRUNCATED AT 250 WORDS)

3T3 Cells↗
PubMed1994

Modulation by polymyxin B of the effects of interferon on human myelogenous leukemia cells.

Natural and recombinant human interferon-alpha (IFN-alpha) and -gamma (IFN-gamma) exert differentiation-inducing and cytocidal effects in vitro on cells of the human myeloblastic leukemia cell line ML-2. These activities of IFNs are modulated by polymyxin B (PMB), a cyclic polycationic peptide antibiotic effective on Gram-negative bacilli. The modulating effect of PMB varies according to the species of IFN, namely, PMB enhances the activities of either natural IFN-gamma or recombinant IFN-gamma, while it inhibits the effects of either natural IFN-alpha or recombinant IFN-alpha. The cause of this variety in PMB effect on IFNs remains to be clarified.

Cell Differentiation↗
PubMed1994

[A case of polyarteritis nodosa who developed rapidly progressive glomerulonephritis and presented with a tumor-like shadow on head CT in the remission stage].

A 70-year-old woman was admitted to our hospital because of weight loss, fever of unknown origin and rapid deterioration of renal function. Polyarteritis nodosa was diagnosed based on the findings of fever, weight loss, thrombocytosis, arthralgia and crescentic glomerulonephritis with vasculitis in the kidney biopsy specimens. Renal function progressively deteriorated and the patient underwent peritoneal dialysis (PD). Methylprednisolone pulse therapy and subsequent oral prednisolone (PSL) therapy combined with cyclophosphamide (CY) was instituted. Renal function gradually recovered and PD was discontinued 2 weeks later. She was discharged after about 2 months of hospitalization and received a monthly follow-up with daily administration of 10mg of PSL and 25mg of CY. Six months after discharge, PN activity was well controlled by PSL and CY, but mental disturbance gradually developed and head CT disclosed a low-density mass shadow that was enhanced with a ring-like appearance by contrast medium similar to a brain tumor. The follow-up CT did not show any enlargement of the mass shadow. One year later, the patient died of uremia and concomitant dementia. Autopsy disclosed cerebral infarct in the relevant site of the mass on CT and the healed stage of angitis in other tissues.

Acute Disease↗
PubMed1994

[A case of membranoproliferative glomerulonephritis due to type II cryoglobulinemia probably associated with hepatitis C virus infection].

In recent years, several laboratories have suggested that chronic hepatitis C virus (HCV) infection is strongly associated with type II cryoglobulinemia (CG) and/or membranoproliferative glomerulonephritis (MPGN). We report here a case of MPGN due to type II CG probably associated with chronic HCV infection, and discuss the pathogenesis and treatment of such cases. A 60-year-old-female was referred to us from a local hospital because of progressive peripheral edema, purpura on the lower limbs, pleural effusion, ascites, hypertension, and renal failure. Laboratory findings indicated proteinuria, abnormal urinary sediments, normochromic normocytic anemia and azotemia. Other laboratory findings included positive rheumatoid factor, elevated serum IgM, hypocomplementemia and elevated circulating immune complexes. Cryoglobulin was detected and found to consist of a mixture of a monoclonal IgM kappa with polyclonal IgG. Renal biopsy showed MPGN. These observations suggested a close association between MPGN and type II CG. We did not find any causes of type II CG except for positive HCV antibody and HCV RNA. Therefore, we made the diagnosis of type II CG associated with chronic HCV infection. Symptoms related to CG was responsiveness to steroid, but development of liver dysfunction developed. Treatment with alfa-interferon (alpha IFN) was added and thereafter, the liver dysfunction improved. However, the serum Cryo level was not reproducibly lowered. While in this case it was unclear whether IFN therapy was beneficial, several reports in addition to the findings of this case suggest a close relation between HCV infection and type II CG and MPGN.(ABSTRACT TRUNCATED AT 250 WORDS)

Cryoglobulinemia↗
PubMed1994

[EC-IC bypass surgery using saphenous vein graft: technical improvement in our experience].

We managed ten cases of EC-IC bypass using a vein graft; six cases with multiple cerebral arterial occlusion and four cases with aneurysm necessitating therapeutic occlusion of the parent artery (Table). Patency of the graft was confirmed in seven cases on long-term follow-up ranging from 7 months to 5 years. Of the ten cases, two died within 7 days after surgery from causes unrelated to the bypass and one was lost in follow-up surgery. Hemorrhagic infarction was observed in two cases, one of which underwent removal of the hematoma. In five cases with cerebral occlusive disease, there were no additional ischemic events and two cases with giant aneurysms showed improvement of visual acuity and extraocular movement. We improved on several surgical techniques for vein graft. We used small hemoclips to occlude branches of the saphenous vein instead of ligating them, which shortens the harvesting time of the saphenous vein. Vessel cannula with a small-sized elegant tip and one-directional valve (DLP, INC., USA) was also used to inflate or deflate vein grafts with saline. It was easily attached to the graft and minimized air entrapment in the lumen. Small clips for microvascular anastomosis (Mizuho INC., Japan) were used to temporarily occlude branches or perforators from the recipient artery. One of the branches of the graft was dissected long enough, through which intraluminal air or thrombus was washed out at the final stage of the surgery. These procedures are useful for shortening occlusion time of the recipient artery and decreasing the risk of embolism.

Adult↗
PubMed1993

Chloroplast-encoded protein as a subunit of acetyl-CoA carboxylase in pea plant.

The gene product of an open reading frame of the chloroplast genome, accD, that has sequence similarity with a subunit of acetyl-CoA carboxylase from Escherichia coli was detected immunochemically in pea chloroplasts. The apparent molecular mass of the accD protein was 87 kDa on SDS-polyacrylamide gel electrophoresis. The protein was acidic and had less mobility than the calculated value, 67,116. Acetyl-CoA carboxylase activity solubilized from pea chloroplasts was inhibited by antibodies against recombinant accD protein. The antibodies precipitated a polypeptide of 35 kDa containing biotin and a polypeptide of 91 kDa together with the 87-kDa-accD protein. The accD protein formed a complex with the molecular mass of about 700 kDa, probably with the 35- and 91-kDa proteins. These results indicate that the chloroplast-encoded polypeptide, accD protein, is a component of a functional acetyl-CoA carboxylase in chloroplasts and this enzyme is a multi-subunit complex, like that from E. coli. The synthesis of accD protein was not induced by light.

Acetyl-CoA Carboxylase↗
PubMed1993

Immunochemical identification of exposed regions of the Na+,K(+)-ATPase alpha-subunit.

A polyclonal antibody against the Na+,K(+)-ATPase holoenzyme was prepared. This antibody recognized native Na+,K(+)-ATPase and inhibited its activity. The peptide fragments corresponding to various regions of the Na+,K(+)-ATPase alpha-subunit, which were synthesized from the cDNA, were immunoprecipitated with the antibody, and the M32-D75, M158-D197 and M470-V552 fragments (the latter included K508, a putative ATP binding site) were identified as the epitopes. The M267-I442 fragment, which included a phosphorylation site at D376, and the C-terminal one-third of the alpha-subunit from M615 to the C-terminus, were not detected using this antibody. These results suggest that at least three regions of the Na+,K(+)-ATPase alpha-subunit, M32-D75, M158-D197 and M470-V552, cover its exposed regions, and that some of them are essential for ATPase activity.

Animals↗
PubMed1993

Phytochrome-regulated expression of the genes encoding the small GTP-binding proteins in peas.

We examined the effect of light on the mRNA levels of 11 genes (pra1-pra9A, pra9B, and pra9C) encoding the small GTP-binding proteins that belong to the ras superfamily in Pisum sativum. When the dark-grown seedlings were exposed to continuous white light for 24 hr, the levels of several pra mRNAs in the pea buds decreased: pra2 and pra3 mRNAs decreased markedly; pra4, pra6, and pra9A mRNAs decreased slightly; the other 6 pra mRNAs did not decrease. We studied the kinetics of mRNA accumulation for pra2, pra3, and pra9B in detail during white light illumination and compared them with those of the phytochrome gene and the small subunit gene of ribulose bisphosphate carboxylase: mRNA levels of pra2 and pra3 decreased in a manner similar to that of phytochrome while that of the small subunit increased as was expected. The decreases were triggered by a 2-min monochromatic red light (660 nm) irradiation. The effect of red light was reversed by subsequent exposure to far-red light, indicating an involvement of phytochrome as a photoreceptor in this light-regulated event. This work reports negative regulation of mRNA levels of small GTP-binding proteins by light, mediated by phytochrome.

Journal Article↗
PubMed1993

Detection of glycosylation abnormality in rheumatoid IgG using N-acetylglucosamine-specific Psathyrella velutina lectin.

Although the galactose deficiency in the Asn297-linked sugar chains of serum IgG from patients with rheumatoid arthritis (RA) has been established, structural analysis of sugar chains has not been readily available. Psathyrella velutina lectin (PVL) preferentially interacts with the N-acetylglucosamine beta 1-->2Man group, exposed at the termini of sugar chains in agalacto IgG. Biotinylated PVL reacted strongly in Western blotting with H chains of IgG derived from patients with RA. An ELISA-based assay for the detection of agalacto IgG was developed using recombinant protein G and biotinylated PVL in combination, and the screening of patients' sera was performed. PVL binding of serum IgG significantly correlated with percentage of galactose-deficient IgG determined by the structural analysis. Age-related slight increase in PVL binding was observed among normal controls. Patients with RA showed significantly higher PVL binding (37.90 +/- 42.25 U/ml, n = 93) as compared with normal controls (5.75 +/- 2.92 U/ml, n = 112) (p = 0.0001). Patients with SLE showed lower but still significant PVL binding (17.86 +/- 5.18 U/ml, n = 10, p = 0.0001). PVL binding correlated with C-reactive protein level in serial analysis of individual RA patients, and was significantly higher in the synovial fluid compared with paired serum samples. PVL binding assay may provide an ideal tool for the simple and sensitive detection of agalacto IgG.

Acetylglucosamine↗
PubMed1993

Regulation of apolipoprotein B production and secretion in response to the change of intracellular cholesteryl ester contents in rabbit hepatocytes.

In the present study, we investigated the mechanisms that regulate apolipoprotein B-100 (apoB) secretion in response to the change of intracellular cholesteryl ester contents by adding low density lipoprotein (LDL) and an inhibitor of 3-hydroxy-3-methylglutaryl-CoA reductase (pravastatin) in rabbit hepatocyte culture system. LDL caused a significant dose-dependent increase in apoB secretion. On the other hand, the addition of pravastatin decreased apoB secretion significantly. LDL caused a dose-dependent increase in cellular cholesteryl ester, while cellular cholesteryl ester was decreased by pravastatin significantly. Therefore, these results indicate that the change of apoB secretion was in parallel with the change of cellular cholesteryl ester contents. Cellular contents of free cholesterol, triglyceride, and phospholipid did not change. To investigate intracellular degradation of apoB prior to secretion, pulse-chase experiments were performed. It was shown that the addition of pravastatin accelerated intracellular degradation of apoB, while LDL slowed the apoB intracellular degradation rate. We also investigated whether the change of cellular cholesteryl ester could affect the apoB mRNA level. Northern blot analysis and solution hybridization RNase protection assay demonstrated that neither LDL nor pravastatin caused a significant change in cellular apoB mRNA level. We conclude that intracellular cholesteryl ester contents play a critical role in apoB secretion, and the intracellular apoB degradation rate could be the main mechanism that regulates apoB secretion in response to the change of intracellular cholesteryl ester level.

Acetates↗
PubMed1993

Chloroplast envelope protein encoded by chloroplast genome.

The gene product of an open reading frame of chloroplast genome, ORF 231 in pea, was immunochemically detected in chloroplast and etioplast envelopes. This is the first protein of a Chloroplast Envelope Membrane encoded by a chloroplast genome. It was named CEM A and the gene, cem A. CEM A is an acidic protein having an apparent molecular mass of 34 kDa on SDS-PAGE, and a minor component detected in the fractionated inner envelope.

Amino Acid Sequence↗
PubMed1993

A cDNA cloning method for monomeric GTP-binding proteins by ligand blotting.

We have developed a convenient method of cDNA cloning for monomeric GTP-binding proteins. The method consists of a serial dilution of cDNA expression library, a separation of proteins by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), and a ligand blotting; each group containing the proteins from about 1000 independent colonies was separated by SDS-PAGE, transferred to nitrocellulose filters, incubated with 10(-9) M [alpha-32P]GTP, and autoradiographed. Separation of proteins by electrophoresis resulted in a drastic reduction of nonspecific binding of labeled GTP to the filters. A serial dilution of colonies resulted in a single clone having GTP-binding activity. We checked about 60,000 colonies and detected two signals. This method is dependent on the ligand specificity of the expressed proteins and is different from the conventional methods based on DNA sequence similarity. This method can be used to isolate cDNAs encoding novel GTP-binding proteins.

Bacteriophage lambda↗
PubMed1993

Different expression of modified low density lipoprotein receptors in rabbit peritoneal macrophages and Kupffer cells.

We have previously reported that mouse peritoneal macrophages have three types of modified low density lipoprotein (LDL) receptors. One is specific for acetylated LDL (Ac-LDL), the second is for oxidized LDL (Ox-LDL), and the third recognizes both (Arai, H. et al. (1989) Biochem. Biophys. Res. Commun. 159, 1375-1382). In the current study, the characteristics of modified LDL receptors in rabbit peritoneal macrophages and Kupffer cells from rabbits were investigated. Cross-competition studies of the degradation assay between Ox-LDL and Ac-LDL in rabbit peritoneal macrophages showed that the degradation of 125I-labeled Ox-LDL was almost completely inhibited by an excess amount of unlabeled Ac-LDL. On the other hand, an excess amount of unlabeled Ox-LDL suppressed 125I-labeled Ac-LDL degradation only partially. In contrast, in Kupffer cells an excess amount of unlabeled Ox-LDL inhibited the degradation of 125I-labeled Ac-LDL almost completely, whereas the degradation of 125I-labeled Ox-LDL was inhibited only partially by Ac-LDL. Scatchard analysis of binding assay showed that rabbit peritoneal macrophages have a single class of receptor for Ox-LDL, which binds maximally 0.31 microgram/mg cellular protein (Bmax) with an apparent dissociation constant (Kd) of 19.3 micrograms/ml, and two classes of receptors for Ac-LDL; one with high affinity (Bmax 0.025 microgram/mg cellular protein, Kd 0.040 micrograms/ml) and the other with low affinity (Bmax 0.08 microgram/mg cellular protein, Kd 11.31 micrograms/ml). On the other hand, Kupffer cells have two classes for Ox-LDL; one is a high affinity receptor (Bmax 0.53 microgram/mg cellular protein, Kd 0.99 microgram/ml) and the other is a low affinity receptor (Bmax 3.71 micrograms/mg cellular protein, Kd 16.2 micrograms/ml) and a single class for Ac-LDL (Bmax 0.60 microgram/mg cellular protein, Kd 7.24 micrograms/ml). These results indicate that rabbit peritoneal macrophages have two kinds of modified LDL receptors; one is specific for Ac-LDL, and the other recognizes both Ox-LDL and Ac-LDL.

Acetylation↗
PubMed1993

Opsonisation of group B streptococci and restriction endonuclease digestion patterns of their chromosomal DNA.

Isolates of group B streptococci (GBS) from neonates with early-onset septicaemia are associated with particular restriction endonuclease digestion patterns (RDP types Ia-3 and III-3) of chromosomal DNA. Opsonophagocytosis of serotype Ia and serotype III GBS isolates was studied by the luminol-enhanced phagocytic chemiluminescence (CL) assay. Pools of serum containing GBS type-specific antibody levels equivalent to or just above levels typically found in sera from mothers of infected infants were used. CL intensities induced by GBS isolates of RDP types Ia-2, Ia-3 and III-3 were lower than those of the other RDP types of the same serotype. Opsonophagocytosis was more efficient with serum containing higher concentrations of type-specific antibodies but for RDP type III-3 strains these differences were much less marked than for other RDP types. CL intensity did not correlate with cell surface charge, hydrophobicity or sialic acid content of GBS. Results demonstrate that certain GBS RDP types are more resistant to opsonophagocytosis and suggest that potentially virulent strains with genetic homogeneity may exist.

Adult↗