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Biomedical subjects

A Nagata

Publications and source records attributed to A Nagata.

At least 19 recordsLinked to original sources
PubMed1995

Characterization of a specific monoclonal antibody 9F5-3a and the development of assay system for oxidized HDL.

We obtained a monoclonal antibody 9F5-3a against oxidative low-density lipoprotein (LDL) modified with CuSO4 and established a sandwich ELISA for detection of oxidized high-density lipoprotein (oxHDL). The 9F5-3a was reacted strongly with oxHDL and to a lesser degree with oxLDL and LDL. In contrast, little or no reactivity was found with HDL. When the generation of oxHDL was limited by the addition of alpha-tocopherol and catalase, reactivity to 9F5-3a was reduced. Incubation of oxHDL with excess lyso-phosphatidylcholine (lyso-PC) also reduced immunoreactivity, but not by only lyso-PC. These results suggested that the epitope is possibly associated with oxHDL-linked lyso-PC induced mainly by the hydroxyl radical.

Animals↗
PubMed1995

M-wave modulation at relative levels of maximal voluntary contraction.

Frequency (mean and median power frequency, f and fm) and amplitude (average rectified and root mean square values, ARV and rms), parameters of the M-wave, and the dorsiflexor force parameters of the anterior tibial muscles were measured in seven healthy human subjects. Intermittent, voluntary contractions at relative intensities (40%, 60%, and 80%) of maximal voluntary contraction (MVC) were performed in conjunction with electrical stimulation. The M-wave parameter changes were measured over the course of the isometric contractions. At higher force levels, M-wave potentiation was observed as increases in both ARV and rms. The ARV augmentation attained levels as high as 206.1 (SD 7.4)% of resting values after both initial and final contractions of 80% MVC, reaching statistical significance (P < 0.01). The f and fm failed to show a significant difference at any level of contraction. It was surmised that potentiation of the M-wave was the result of an increased contribution of muscle fibre type IIb recruited during higher contraction levels, reflecting the change to larger, deeper innervating motoneurons as the intensity of contraction, as a percentage of MVC, rose. Recruitment of type IIb fibres, which have been reported to have a higher energy potential and frequency content, were thought to reflect changes in the local excitability threshold of some motor units as the force intensity increased during the intermittent voluntary contractions. It is suggested that the M-wave elicited after contractions has the potential to reflect, to some extent, motor unit recruitment changes resulting from the preceding contractions, and that through comparisons of M-wave amplitude parameters contributions of varying fibre types over the course of a contraction may be indicated.

Adult↗
PubMed1994

Carbohydrate-mediated recognition of a circulating placental alkaline phosphatase-immunoglobulin M complex.

We detected an abnormal alkaline phosphatase (AP) electrophoretically in the serum of a patient with rheumatoid arthritis, who had a macromolecular AP linked with immunoglobulin M (IgM) bearing a kappa light chain. The IgM isolated from the AP-IgM complex in the patient's serum reacted apparently with all of the AP isozymes tested, i.e. those originating in the liver, bone, intestine and placenta, but the alpha-mannosidase-treated IgM from the patient's serum bound to placental AP (PAP) alone. This suggests that untreated IgM recognizes multivalent epitopes of the AP and that the complex of AP with alpha-mannosidase-treated IgM is a specific antibody-antigen complex. In order to investigate further the multivalent binding capacity for the PAP-untreated IgM complex, we prepared a monoclonal antibody (MoAb) against PAP and identified it as an IgM with a kappa light chain. The binding affinities and their circulating half-lives of the synthetic complexes of PAP and respective MoAbs were examined with and without treatment with several glycosidases. The untreated MoAb bearing IgM had binding affinity for all of the AP isozymes tested, while alpha-mannosidase-treated IgM attached only to PAP, the same as the IgM isolated from the PAP-IgM complex in the patient's serum. The circulating clearance of the PAP-IgM complex in rabbits was faster than either component alone. In addition, the PAP-IgM complex treated with alpha-mannosidase was found to have the shortest half-life of all the complexes of PAP and Igs treated with the several glycosidases tested. These results suggest that the formation of the PAP-IgM complex as an enzyme-linked antibody and the clearance of the complex in vivo are dependent on the sugar moieties of the Igs.

Adult↗
PubMed1992

Elongation factor-1 alpha gene determines susceptibility to transformation.

Elongation factor-1 alpha (EF-1 alpha), an essential component of the eukaryotic translational apparatus, is a GTP-binding protein that catalyses the binding of aminoacyl-transfer RNAs to the ribosome. Expression of the EF-1 alpha gene decreases towards the end of the lifespans of mouse and human fibroblasts, but forced expression of EF-1 alpha prolongs the lifespan of Drosophila melanogaster. Eukaryotic initiation factor-4E, another component of the translational machinery, is mitogenic or oncogenic when constitutively expressed in some mammalian cells. Thus, components of the protein synthesis apparatus seem to be involved in the control of cell proliferation. Using expression cloning, we have isolated a complementary DNA clone from a BALB/c 3T3 mouse fibroblast variant, A31-I-13 (ref. 10), which specifies a factor determining the susceptibility of BALB/c3T3 to chemically and physically induced transformation. Here we report that the factor is EF-1 alpha and that its constitutive expression causes BALB/c 3T3 A31-I-1 (ref. 10), C3H10T1/2 (ref. 11) and Syrian hamster SHOK fibroblasts to become highly susceptible to transformation induced by 3-methylcholanthrene and ultraviolet light. EF-1 alpha messenger RNA is also constitutively expressed in a quiescent culture of the highly susceptible variant A31-I-13. We conclude that the removal of regulation of the expression of these components of the translational machinery may predispose cells to become more susceptible to malignant transformation.

3T3 Cells↗
PubMed1992

Structural organization of the gene for prostaglandin D synthase in the rat brain.

A 3-kilobase-pair gene for rat brain prostaglandin D synthase [(5Z,13E)-(15S)-9 alpha,11 alpha-epidoxy-15-hydroxyprosta-5,13- dienoate D-isomerase, EC 5.3.99.2], which belongs to the lipocalin family, was isolated from a rat genomic DNA library by plaque hybridization with the cDNA for the enzyme. The gene contains seven exons, and all the splice donor and acceptor sites conform to the GT/AG rule. Transcription initiates at a guanine residue 39 base pairs upstream of the translation initiation codon, as determined by primer-extension analysis of rat brain mRNA. The 5'-flanking region of the gene lacks typical transcriptional regulatory sequences, such as TATA and CAAT boxes, but contains several sets of inverted repeats, direct repeats, and sequences resembling the transcriptional factor Sp1-binding site. The gene structure of prostaglandin D synthase is remarkably analogous to those of other lipocalins, such as beta-lactoglobulin, alpha 2-urinary globulin, placental protein 14, and alpha 1-microglobulin, in terms of number and sizes of exons and phase of splicing of introns. Furthermore, in a multiple alignment of the deduced amino acid sequences, positions of exon/intron junction of the prostaglandin D synthase gene are highly conserved and located around the positions of those of the genes for other lipocalins despite a weak homology.

Amino Acid Sequence↗
PubMed1992

A marked molecular heterogeneity of growth hormone (GH) detected in the plasma but not pituitary of a patient with acromegaly: comparison with other acromegalics and an implication for discrepant plasma levels of GH and insulin-like growth factor.

We experienced a 41-year-old acromegalic male (Case 1) in whom the basal plasma GH was extremely high (320-450 ng/mL) but plasma IGF-I was only slightly elevated (2.0-2.8 U/mL). His nutritional condition and associated diabetes mellitus did not appear to be responsible for the relatively low IGF-I level, and a GH-autoantibody in the plasma was absent. We thus performed gel filtration analyses of his plasma and somatotroph adenoma to determine elution patterns of immunoreactive (IR) and receptor active (RA) GH. For comparison, the same studies were carried out on plasmas and somatotroph adenomas obtained from three other acromegalics (Cases 2-4) whose basal plasma GH and IGF-I levels were 22-45 ng/mL and 3.5-6.0 U/mL, respectively. IR GH in Case 1's plasma distributed over an extremely wide range keeping similar titers rather than showing three discernible components (big-big, big, and little GH) as did plasmas and adenomas from Cases 2-4. And, most of the IR GH in Case 1's plasma was eluted in such fractions that contained low levels of RA GH, indicating a minor proportion of biologically active GH. However, interestingly, the chromatographic profile and total GH content of Case 1's adenoma were similar to those of Cases 2-4's adenomas. These results may, at least in part, explain the discrepancy between the plasma GH and IGF-I levels of Case 1. The unexpectedly different GH elution patterns between the plasma and adenoma from this patient, may suggest a contribution of certain plasma factor(s) to the unusual chromatographic profile of plasma GH.

Acromegaly↗
PubMed1992

Generation of plasma kinin by three types of protease isolated from Porphyromonas gingivalis 381.

Three types of protease (A, B and C) isolated from the culture supernatant of Porphyromonas gingivalis 381 had peculiar activities on kinin generation from high molecular-weight kininogen in vitro. Protease C released bradykinin from the kininogen in a reaction mixture containing 2 mM dithiothreitol, but A and B did not. However, the activity of degrading bradykinin was much stronger in protease A and B than in C. These findings suggest that only protease C shows plasma kallikrein activity.

Bradykinin↗
PubMed1992

Biological potency of a fluorinated vitamin D analogue in hypoparathyroidism.

Several in vivo experiments have revealed that a synthesized fluorinated analogue of vitamin D, 26,26,26,27,27,27-hexafluoro-1,25-dihydroxyvitamin D3 (26,27-F6-1,25(OH)2D3) has a higher and longer-lasting biological activity than 1,25(OH)2D3 in calcium regulating actions. We evaluated the biological potency and the availability for clinical use of this compound in hypocalcemia associated with hypoparathyroidism. In an experimental setting, daily administration of 650 pmol/kg of 26,27-F6-1,25(OH)2D3 showed an equivalent effect to that of 3250 pmol/kg of 1,25(OH)2D3 in elevating whole blood ionized calcium levels in parathyroidectomized rats. Furthermore, an additional clinical study demonstrated that 0.5-1.5 micrograms/day of 26,27-F6-1,25(OH)2D3 were considered adequate maintenance doses in various types of hypoparathyroidism and that changes of medication to the same doses of 1,25(OH)2D3 resulted in prompt decline of urinary calcium excretion and of whole blood ionized calcium levels, and in recurrence of symptoms related to hypocalcemia. Although the mechanism responsible for the high potency of this analogue remains unclear, our experience confirms that 26,27-F6-1,25(OH)2D3 has higher biological activities in bone calcium mobilization and is more potent than 1,25(OH)2D3 in correcting hypocalcemia of hypoparathyroidism in a hospital setting.

Animals↗
PubMed1992

Survey of a receptor protein in human erythrocytes for hemagglutinin of Porphyromonas gingivalis.

The purpose of this study is to survey a receptor protein in human erythrocyte membrane for the hemagglutinin (HA) of Porphyromonas gingivalis. Human erythrocytes were modified by either chymotrypsin or P. gingivalis HA along with the disappearance of their hemagglutinating ability and the removal of the band 3 protein. By preparative electrophoresis, this protein was isolated and purified from human erythrocytes. The purified protein showed strong inhibitory activity for hemagglutination and the binding to P. gingivalis cells, whose binding sites were calculated to be approximately 9000, suggesting its binding to the active site of HA. Hemagglutinin purified from P. gingivalis by affinity absorption to sheep erythrocyte ghosts possessed strong trypsin-like activity, and both the HA and the enzyme activities were inhibited by arginine. Specific modification of arginyl residues in human erythrocytes by phenylglyoxal diminished the hemagglutinating ability. From the similarity of the inhibition profile and possible active sites between HA and the trypsin-like protease, it is suggested that hemagglutination may occur as a result of the primary reaction of the enzyme (protease) and the substrate. These results suggest that band 3 may be a key protein in human erythrocyte membrane for HA from P. gingivalis and its binding sites may be arginyl residues of the protein.

Aminopeptidases↗
PubMed1992

Eosinophilia associated with chronic pancreatitis: an analysis of 122 patients with definite chronic pancreatitis.

Among 122 patients with chronic pancreatitis, marked eosinophilia (greater than 500 eosinophils/mm3 in the peripheral blood) was observed in 21 cases (17.2%). All of the affected patients were males, and there was no significant difference in the incidence of eosinophilia between patients with alcoholic and nonalcoholic pancreatitis. In the patients with eosinophilia, endocrine pancreatic function was maintained comparatively well, despite marked exocrine pancreatic dysfunction. The eosinophilia of chronic pancreatitis frequently developed in association with severe damage to neighboring organs (pleural effusion, pericarditis, and ascites), as well as in association with pancreatic pseudocyst. Our findings suggest that there is a close correlation between marked eosinophilia and severe tissue injury during acute exacerbations of chronic pancreatitis.

Adult↗
PubMed1992

[Fluorescein fundus angiography of optic nerve head in primary open angle glaucoma and low tension glaucoma].

Fluorescein fundus angiography was performed at angle of 20 degrees in the 58 low tension glaucoma (LTG) eyes (30 cases) and 77 primary open angle glaucoma (POAG) eyes (41 cases) and the relation of the optic nerve head fluorescein changes to visual field disturbances (stage classification of Kosaki) was compared between POAG and LTG groups. The filling defect of fluorescein in the deep area and the decrease in number of superficial capillaries were observed in the optic nerve head. The filling defect area of fluorescein in the optic nerve head corresponding to Bjerrum scotoma was recognized even in the mild visual field disturbance cases of both LTG and POAG. The following findings were noted in both LTG and POAG cases; expansion of the filling defect area and the decrease in number of superficial capillaries in the same area with progression of visual field disturbances. Filling defect area of fluorescein of the optic nerve head accorded with visual field disturbance area in 19 LTG eyes (32.8%) and 61 POAG eyes (79.2%). On the contrary, the filling defect area of the optic nerve head was wider than the visual disturbance area in 37 LTG eyes (63.8%) and 16 POAG eyes (20.8%). These findings suggest that blood circulatory disorders of the optic nerve head occurred earlier in LTG than in POAG and that the development of LTG might be closely associated with the blood circulatory disorders.

Aged↗
PubMed1992

[Possible mechanisms of inositol phosphate-diacylglycerol signalling pathway in the regulation of intraocular pressure].

To clarify the role of the inositol phosphate diacylglycerol (IP/DAG) signalling pathway in the regulation of intraocular pressure (IOP), the effect of tumor promoter phorbol ester (PMA) and Ca ionophore (A23187) on IOP responses was examined in albino rabbits. PMA stimulates protein kinase C (PKC) directly and A23187 elevates intracellular Ca2+ concentration. In this study, the topical application of 10 microM PMA or 15 microM A23187 slightly reduced IOP. However topical application of both 10 microM PMA and 15 microM A23187 significantly reduced IOP. The maximum IOP decrease was 5.0 mmHg. This decrease was inhibited by pretreatment with 0.5 microM staurosporin, a PKC inhibitor. Quantitative changes of inositol 1,4,5-trisphosphate (IP3) and PKC activity in cultured ciliary epithelia (CE), stimulated with several ocular hypotensive agents were also studied. When cultured CE was stimulated with 50 microM carbachol, the PKC activity and IP3 content rapidly increased. When CE was stimulated with 50 microM epinephrine, isoproterenol or timolol, PKC activity did not show any change and IP3 level declined. These studies suggest that the IP/DAG signalling pathway somehow mediates aqueous dynamic changes in ciliary epithelia.

Animals↗
PubMed1991

Wee1(+)-like gene in human cells.

The wee1+ gene is a mitotic inhibitor controlling the G2 to M transition of the fission yeast Schizosaccharomyces pombe and encodes a protein kinase with both serine- and tyrosine-phosphorylating activities. We have cloned a human gene (WEE1Hu) similar to wee1+ by transcomplementation of a yeast mutant. WEE1Hu encodes a protein homologous to the S. pombe wee1+ and mik1+ (a functionally redundant sibling of wee1+) kinases and effectively rescues a wee1 mutation. We report here that overexpression of WEE1Hu in fission yeast generates very elongated cells as a result of inhibition of the G2-M transition in the cell cycle. In addition, we detected a 3-kilobase-long WEE1Hu messenger RNA in all the human cell lines we examined. We conclude that a wee1(+)-like gene exists and is expressed in human cells.

Amino Acid Sequence↗
PubMed1991

Human brain prostaglandin D synthase has been evolutionarily differentiated from lipophilic-ligand carrier proteins.

cDNAs for glutathione-independent prostaglandin D synthase were isolated from cDNA libraries of human brain. The longest cDNA insert was 837 base pairs long and contained a coding region of 570 base pairs corresponding to 190 amino acid residues with a calculated Mr of 21,016. Between two cDNA inserts isolated from the two different libraries, nucleotide substitutions were observed at 16 positions, including conservative amino acid substitutions at 2 positions and nonconservative substitutions at 5 positions, indicating genetic heterogeneity of this enzyme in humans. The computer-assisted homology search revealed that the enzyme is a member of the lipocalin superfamily, comprising secretory hydrophobic molecule transporters, showing the greatest homology (28.8-29.4% identity; 51.3-53.1% similarity) to alpha 1-microglobulin among the members of this superfamily. In a phylogenetic tree of the superfamily, this enzyme, alpha 1-microglobulin, and the gamma chain of the complement component C8 form a cluster separate from the other 14 members. The two distinctive characteristics of glutathione-independent prostaglandin D synthase, as compared to the other members of this superfamily, are its enzymatic properties and its association with membranes that were probably acquired after evolutionary divergence of the two lipocalins. Based on the observed sequence homology, the tertiary structure of the enzyme was deduced to consist of an eight-stranded anti-parallel beta-barrel forming a hydrophobic pocket. Furthermore, the Cys-65 residue in the pocket, which is conserved only in the human and rat enzymes but not in other lipocalins, was considered to be a putative active site of the enzyme.

Amino Acid Sequence↗
PubMed1991

Surface electromyogram spectral characterization and motor unit activity during voluntary ramp contraction in men.

The relationships were investigated between the surface electromyographic (SEMG) power spectrum analysed by the 20 order autoregressive model (AR spectrum) and underlying motor unit (MU) activity during isometric contractions increasing linearly from 0% to 80% maximal voluntary contraction. Intramuscular spikes and SEMG signals were recorded simultaneously from biceps brachii muscle; the former were analysed by a computer-aided intramuscular MU spike amplitude-frequency (ISAF) histogram and the latter subjected to AR spectral analysis. Results indicated that there was a positive correlation between the force output and the mean amplitude of the ISAF histogram but not with the mean frequency. These changes were accompanied by changes in relative power of the high frequency (100-200 Hz) peak (HL) in the AR spectrum. It was also found that there was a positive correlation between the mean amplitude of the ISAF histogram and the HL value. These data suggested that the power of the high frequency peak in the AR spectrum of the SEMG signal preferentially reflected the progressive recruitment of underlying MU according to their size. Differences between the AR spectrum and the spectrum estimated by fast Fourier transform algorithm have also been discussed.

Adult↗
PubMed1991

Serological studies of Porphyromonas (Bacteroides) gingivalis and correlation with enzyme activity.

Porphyromonas gingivalis from the human oral cavity was serologically characterized using absorbed and unabsorbed rabbit antisera. The reference strains were ATCC 33277, W50, W83, 381 and hara 1. The 432 isolates were from periodontal pockets of 63 patients with adult periodontitis. Using sonicated antigens, four serotypes were identified by immunodiffusion tests and immunoelectrophoresis. Each patient harbored only one serotype of P. gingivalis, and serotypes I and IV predominated. The incidence of serotype I was four times higher than that of serotype II, and approximately seven times higher than that of serotype III. The collagenolytic and some proteolytic enzymes of representatives of each serotype were assessed. Although all strains produced these enzymes to some degree, some differences in their levels were observed. Serotype II strains were more collagenolytic than serotypes I or III, and serotype III exhibited lower activities of N-CBz-glycyl-glycyl-arginyl peptidase than other serotypes. Antibiotic sensitivity was also compared with antimicrobial disks, and serotype IV strains exhibited high sensitivity to the four antibiotics used.

Anti-Bacterial Agents↗
PubMed1991

Sandwich assay for carcinoembryonic antigen with immobilized lectins and a monoclonal antibody.

A lectin-linked immunoradiometric assay (L-IRMA) using 7 different lectins and a monoclonal antibody (MoAb) directed against the protein moiety-specific epitope was developed to detect carcinoembryonic antigen (CEA). The method used for L-IRMA was as follows: certain CEAs that reacted with lectin agarose beads were allowed to bind further to an 125I-labeled anti-CEA MoAb, and the resulting trapped 125I-MoAb was counted in a gamma counter. From the results, CEAs which interacted with Phaseolus vulgaris erythroagglutinin and leukoagglutinin were presumed to contain the complex type of sugar chains. Furthermore, CEAs interacting specifically with wheat germ agglutinin lectin were found in the tested samples, suggesting that the CEA had a hybrid or a complex type of sugar chain as the core structure of the sugar chain, except for that in seminal plasma. These results obtained by L-IRMA were in good accord with the data obtained from serial lectin affinity chromatography. L-IRMA may therefore be a simple method to study the glycoprotein heterogeneities in tumors and in normal subjects.

Antibodies, Monoclonal↗