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Biomedical subjects

K Asai

Publications and source records attributed to K Asai.

At least 127 records · Page 7Linked to original sources
PubMed1997

Isolation of a rat histidase cDNA sequence and expression in Escherichia coli--evidence of extrahepatic/epidermal distribution.

Histidase (histidine ammonia-lyase) is a cytosolic enzyme responsible for catalyzing the non-oxidative deamination of histidine to urocanic acid. Full-length cDNAs encoding rat histidase have been isolated from a lambdaZAP liver cDNA library using a partial cDNA fragment obtained by PCR. Whereas the initial description of the rat histidase 3' untranslated sequence contained a rare polyadenylation signal sequence, the data presented encompass a more distant 28-bp region, possessing a nucleotide stretch (AATATAAA), identical to that in the mouse histidase cDNA. Dideoxynucleotide chain-termination sequencing of two clones obtained by in vivo excision yielded an additional 376 bp and 105 bp of 5' and 3' untranslated sequences, respectively. A selected rat histidase cDNA clone was introduced into the pET-16b prokaryotic vector and expressed in BL21(DE3)pLysS Escherichia coli. After purification by nickel-chelation chromatography, recombinant histidine-tagged protein was employed to raise anti-(rat histidase) immunoglobulin in a Japanese white rabbit. The polyclonal rabbit antibody recognized and formed immune complexes with rat and recombinant human histidase proteins. Immunoblots of crude rat organ extracts detected a spectrum of histidase expression extending beyond that observed in liver and skin. Among other histidase-positive cells were those of the renal cortex tubular epithelium, fundic mucosal glands of stomach, gastric intramuscular (Auerbach's) plexus, and adrenal cortex. Immunohistochemical studies of histidase in rat liver produced discrete staining of hepatocytes in association with portal triads (Rappaport zone I). Furthermore, in contrast with previous reports of activity confined to epidermal stratum corneum, our findings demonstrate immunoreactive protein within and limited to the adjacent stratum granulosum.

Amino Acid Sequence↗
PubMed1997

Probing of the membrane topology of sarcoplasmic reticulum Ca2+-ATPase with sequence-specific antibodies. Evidence for plasticity of the c-terminal domain.

The topology of Ca2+-ATPase in sarcoplasmic reticulum (SR) vesicles was investigated with the aid of sequence-specific antibodies, produced against oligopeptides corresponding to sequences close to the membranous portions of the protein. The antisera in competitive enzyme-linked immunosorbent assays only reacted with intact SR vesicles to a limited extent, but most epitopic regions were exposed by low concentrations of nondenaturing detergent, octaethylene glycol dodecyl ether (C12E8) or after removal of cytosolic regions by proteinase K. In particular, these treatments exposed the loop regions in the C-terminal domain, including L7-8, the loop region located between transmembrane segments M7 and M8, with a putative intravesicular position, which had immunochemical properties very similar to those of the C terminus with a documented cytosolic exposure. In contrast to this, the reactivity of the N-terminal intravesicular loop regions L1-2 and L3-4 was only increased by C12E8 treatment but not by proteinase K proteolysis. Complexation of Ca2+-ATPase with beta,gamma-CrATP stabilized the C-terminal domain of Ca2+-ATPase against proteinase K proteolysis and reaction with most of the antisera, but immunoreactivity was maintained by the L6-7 and L7-8 loops. Immunoelectron microscopic analyses of vesicles following negative staining, thin sectioning, and the SDS-digested freeze-fracture labeling method suggested that the L7-8 epitope, in contrast to L6-7 and the C terminus, can be exposed on either the intravesicular or cytosolic side of the membrane. A preponderant intravesicular location of L7-8 in intact vesicles is suggested by the susceptibility of this region to proteolytic cleavage after disruption of the vesicular barrier with C12E8 and in symmetrically reconstituted Ca2+-ATPase proteoliposomes. In conclusion, our data suggest an adaptable membrane insertion of the C-terminal Ca2+-ATPase domain, which under some conditions permits sliding of M8 through the membrane with cytosolic exposure of L7-8, of possible functional significance in connection with Ca2+ translocation. On the technical side, our data emphasize that extreme caution is needed when using nondenaturing detergents or other treatments like EGTA at alkaline pH to open up vesicles for probing of intravesicular location with antibodies.

Animals↗
PubMed1997

Effects of cardiac denervation on development of heart failure and catecholamine desensitization.

BACKGROUND: Two signatures of heart failure are activation of the sympathetic nervous system and catecholamine desensitization. However, whether or not the elimination of cardiac nerves affects either the progression of heart failure or catecholamine desensitization is not clear. METHODS AND RESULTS: We studied 8 dogs with selective ventricular denervation (VD) (surgical technique) and 10 intact dogs, chronically instrumented for measurement of left ventricular (LV) and arterial pressures, LV dP/dt, LV internal diameter, and wall thickness before and after heart failure was induced by rapid pacing (240 bpm) for 3 to 4 weeks. VD was confirmed by the absence of reflex effects induced by intracardiac veratrine and depletion of tissue norepinephrine and by supersensitive responses to norepinephrine. During the development of heart failure, LV end-systolic and end-diastolic stresses and heart rate increased, while myocardial contractility, as reflected by LV dP/dt and mean velocity of circumferential fiber shortening corrected for heart rate (Vcf(c)), decreased in both intact and VD dogs. However, the increases in LV end-diastolic stress and decreases in LV dP/dt as well as the relationship between LV systolic stress and Vcf(c) in heart failure were less (P<.05) in VD dogs. The responses of LV dP/dt and heart rate to both isoproterenol and norepinephrine in intact dogs were reduced in heart failure. The physiological desensitization to the inotropic effects of isoproterenol and norepinephrine was less in dogs with VD (P<.05), but chronotropic responses were similar because atrial innervation remained intact. Plasma norepinephrine levels were not different in VD dogs (592+/-79 pg/mL) compared with intact dogs (576+/-81 pg/mL) in heart failure. CONCLUSIONS: Dogs with selective VD tolerated the development of heart failure better than intact dogs and demonstrated significantly less catecholamine desensitization. The latter indicates that intact ventricular innervation is required for physiological expression of catecholamine desensitization despite comparable elevation of plasma catecholamines during the development of heart failure.

Adrenergic alpha-Agonists↗
PubMed1997

Glucocorticoid induced the expression of mRNA and the secretion of lipocortin 1 in rat astrocytoma cells.

The lipocortins are a family of structurally related proteins that have been shown to be implicated in multiple aspects of cell biology. Subsequent research has shown that lipocortin 1 (LC1) participates in the physiological and pathological functioning of the CNS and neuroendocrine system. In the present study, the effects of 12-O-tetradecanoylphorbol 13-acetate (TPA), dibutyryl cyclic AMP (Bt2cAMP) or dexamethasone (DEX) on expression of LC1 were investigated by a sandwich enzyme immunoassay and reverse transcription polymerase chain reaction (RT-PCR) in rat astrocytoma (C6) cells. Time-dependent experiments revealed that the intracellular protein content and the mRNA of rat LC1 increased significantly 4 h after TPA (10 mM) or DEX (1 microM) addition. TPA and DEX elicited a prominent induction of LC1 at 10(-8) M and 10(-6) M, respectively. Bt2cAMP (0.5 mM) also appeared to induce, but the induction was not statistically significant. In addition, DEX increased the extracellular secretion of LC1 without cytotoxicity. These results suggest that LC1 synthesis is chemically induced and selectively released from C6 cells by dexamethasone.

Animals↗
PubMed1997

Beta-adrenergic receptor signalling in stunned myocardium of conscious pigs.

The primary goal of this study was to compare the effects of isoproterenol which stimulates beta-adrenergic receptors and forskolin, and NKH 477, a water soluble derivative of forskolin, which stimulate adenylyl cyclase in stunned myocardium of conscious pigs, previously instrumented for measurements of left ventricular pressure and dP/dt, arterial pressure, and wall thickening. Ten min of coronary artery occlusion induced transmural reductions in blood flow (radioactive microspheres) in subepicardium (-98 +/- 2%) and subendocardium (-99 +/- 1%). Wall thickening (piezoelectric crystals) fell from 2.50 +/- 0.26 mm to -0.26 +/- 0.26 mm and remained depressed at 1.37 +/- 0.19 mm after 20-30 min coronary artery reperfusion, reflecting myocardial stunning. At that time, isoproterenol (0.2 microgram/kg) increased wall thickening in stunned myocardium (+1.40 +/- 0.16 mm, P < 0.05) more than in control (+0.71 +/- 0.22 mm), while forskolin elicited the opposite effects. NKH 477 (30 micrograms/kg), which does not penetrate the blood-brain barrier, increased systolic wall thickening similarly before (+0.95 +/- 0.25 mm) and during (+1.01 +/- 0.24 mm) myocardial stunning. The reflex inotropic responses to inferior vena caval occlusion on wall thickening were diminished, P < 0.05, in the stunned myocardium (+0.53 +/- 0.05 mm) compared with control (+0.95 +/- 0.07 mm). beta-adrenergic receptor density, which was quantitated with 125I-cyanopindolol binding, was increased transmurally in stunned myocardium compared with non-ischemic myocardium (subepicardium: +23 +/- 5%, subendocardium: +34 +/- 13%, P < 0.05). Basal and forskolin-stimulated adenylyl cyclase activities were decreased slightly, but significantly, in the stunned subendocardium but not in the subepicardium, while isoproterenol stimulation of adenylyl cyclase activity showed no differences. In summary, paradoxical responses to beta-adrenergic receptor stimulation were observed in stunned myocardium, with pharmacological stimulation with isoproterenol evoking enhanced responses, and neural stimulation with inferior vena caval occlusion eliciting depressed responses. The diminished responses to forskolin in vivo, in stunned myocardium were out of proportion to the biochemical measurements, and may be attributed to neurally mediated cardiac effects of forskolin, since the responses to direct stimulation of adenylyl cyclase by NKH 477 were preserved.

Adenylyl Cyclases↗
PubMed1997

Life events and anxiety in Chinese medical students.

The authors studied a sample of 537 Chinese medical students aged 15-21 years using Zung's Self-Rating Anxiety Scale (SAS) and a life events checklist. The results showed that test pressure, less free time, peer competition, failure in a test, and financial problems were the most common stressful experiences for medical students during the previous 12 months. Social and personal problems were rated the highest on scores of perceived stress. Of all students, 12.5% scored over the cut-off point on the SAS previously established to indicate risk of psychiatric disorder. Using a stepwise regression analysis, it was shown that poor health status, little physical exercise, financial problems in the family, test pressure, conflict with classmates, the personality trait of introversion, getting up late in the morning, and freshman status were independently associated with the presence of anxiety.

Adolescent↗
PubMed1997

A rare case of gastric cancer in an acromegalic patient.

Although it has been demonstrated that acromegalic patients have an increased risk of neoplasms, especially colon neoplasms, gastric cancer with acromegaly is very rare--only five cases have been reported to date in Japan. We report here a rare case of gastric cancer with acromegaly in a 58-year-old woman, whose acromegalic change began at age 44. This patient showed typical clinical features of acromegaly, with increased concentrations of blood growth hormone (GH) and insulin-like growth factor I (IGF-I); she had four types of neoplasms; gastric cancer, colon tubular adenoma with moderate atypia, pancreatic mucinous cystadenoma, and subcutaneous lipoma. The gastric cancer was macroscopically 0-IIc type, 3.0 x 2.5 cm in size, and histologically diagnosed as a poorly differentiated adenocarcinoma with limited invasion of the mucosal layer. The previously documented stimulatory effects of GH and/or IGF-I on tumorigenesis and cell proliferation may have been responsible for the development of the multiple neoplasms in our patient.

Acromegaly↗
PubMed1997

Specific detection of kappa light chain in uric acid stones.

Proteins were extracted from uric acid stones with 6M guanidine chloride (pH 8.5), which were successively developed by 12% polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate (SDS-PAGE). Amino acid sequence analysis of each band on SDS-PAGE revealed that major components in uric acid stones were immunoglobulin alpha heavy and kappa light chains. Although immunoglobulin heavy chain (gamma and mu, as well as alpha) and a kappa light chain were clearly detected in uric acid stones by Western blotting using their specific antibodies, no lambda chains whatsoever could be detected. The results suggest that immunoglobulins selectively containing kappa light chain might have specific functions in uric acid stone formation as stone matrices.

Amino Acid Sequence↗
PubMed1997

Evidence for participation of gliostatin/platelet-derived endothelial cell growth factor in gastric ulcer healing.

Gliostatin (GLS)/Platelet-derived endothelial cell growth factor (PD-ECGF) is a protein factor that has angiogenic and thymidine phosphorylase activity. It has been recently demonstrated to be related to disease activity in rheumatoid arthritis. However, its physiological role in the gastric mucosa is unknown. In the present study, concentrations of this protein in human gastric mucosa and plasma were evaluated. Further, the effect of purified human GLS/PD-ECGF on experimental ulcer healing was investigated in the rat. The human plasma concentration of GLS/PD-ECGF was significantly higher in patients with intractable gastric ulcer than in patients with significant resolution. The tissue content was significantly higher at the gastric ulcer edge than in either the fundic or pyloric region. GLS/PD-ECGF infusion delayed ulcer healing in a dose-dependent manner. These results suggest that gastric tissue and/or circulating GLS/PD-ECGF may participate in pathology and etiology of gastric ulcers and that this mechanism may relate to the pathogenesis of RA.

Animals↗
PubMed1997

Gliostatin/platelet-derived endothelial cell growth factor as a clinical marker of rheumatoid arthritis and its regulation in fibroblast-like synoviocytes.

The objective was to assess the congruity of gliostatin/platelet-derived endothelial cell growth factor (GLS PD-ECGF) with other clinical markers of rheumatoid arthritis (RA) and to define its molecular mechanism of action in the complicated cytokine network during RA pathogenesis. Immunoassay systems were used to quantify GLS or cytokine levels in laboratory and clinical samples. Expression levels of GLS were determined by reverse transcription-polymerase chain reaction methods. The GLS levels in synovial fluid were correlated with interleukin-1 (IL-1) and IL-8. The serial data of serum GLS levels reflected well changes in the disease activity during the clinical course of four representative patients with RA. In cultured fibroblast-like synoviocytes, tumour necrosis factor-alpha (TNF-alpha), IL-1, IL-6 and IL-8 induced GLS expression. In conclusion, our results suggest that the serum GLS level, mostly derived from cytokine-stimulated synoviocytes, was a useful clinical marker of RA.

Arthritis, Rheumatoid↗
PubMed1997

Isolation and characterization of a sporulation initiation mutation in the Bacillus subtilis secA gene.

A Bacillus subtilis secA mutant, secA12, which is blocked at an early stage of sporulation, is able to grow as well as the wild-type strain at all temperatures tested. Experiments with lacZ fusion genes showed that the induction of kinA expression, as well as the sporulation-specific transcription of the spo0A gene, was not observed in the secA12 mutant. However, transcription of the spo0H gene (coding for sigmaH, which is required for the transcription of kinA and spo0A) and accumulation of the sigmaH protein were not affected in secA12. These results suggested that mutations in secA affect a factor required for efficient transcription of kinA as well as for the activation of the phosphorelay pathway.

Adenosine Triphosphatases↗
PubMed1997

Downregulation of caveolin by chronic beta-adrenergic receptor stimulation in mice.

Caveolae, flask-shaped invaginations of cell membranes, are believed to play pivotal roles in transmembrane transportation of molecules and cellular signaling. Caveolin, a structural component of caveolae, interacts directly with G proteins and regulates their function. We investigated the effect of chronic beta-adrenergic receptor stimulation on the expression of caveolin subtypes in mouse hearts by immunoblotting and Northern blotting. Caveolin-1 and -3 were abundantly expressed in the heart and skeletal muscles, but not in the brain. Continuous (-)-isoproterenol, but not (+)-isoproterenol, infusion via osmotic minipump (30 micrograms.g-1.day-1) for 13 days significantly downregulated both caveolin subtypes in the heart. The expression of caveolin-1 was reduced by 48 +/- 6.1% and that of caveolin-3 by 28 +/- 4.0% (P < 0.01, n = 8 for each). The subcellular distribution of caveolin subtypes in ventricular myocardium was not altered as determined by sucrose gradient fractionation. In contrast, the expression of both caveolin subtypes in skeletal muscles was not significantly changed. Our data suggest that the expression of caveolin subtypes is regulated by beta-adrenergic receptor stimulation in the heart.

Adrenergic beta-Agonists↗
PubMed1997

Cardiomyopathy induced by cardiac Gs alpha overexpression.

The goal of this study was to determine whether chronic endogenous sympathetic stimulation resulting from the overexpression of cardiac stimulatory G protein alpha subunit (Gs alpha) in transgenic mice (15.3 +/- 0.1 mo old) resulted in a clinical picture of cardiomyopathy. The left ventricular ejection fraction, measured by echocardiography, was reduced in older mice with Gs alpha overexpression (50.4 +/- 5.4%) compared with age-matched control mice (70.9 +/- 1.6%; P < 0.05). When ejection fractions were compared at similar heart rates, the Gs alpha mice exhibited a greater left ventricular end-diastolic dimension than control mice (4.3 +/- 0.2 vs. 3.7 +/- 0.1 mm; P < 0.05). Baseline heart rates were elevated in conscious Gs alpha mice (722 +/- 27 beats/min; n = 5) compared with control mice (656 +/- 28 beats/min; n = 5). Moreover, electrocardiographic monitoring demonstrated a high incidence of arrhythmias. Increased mortality compared with control mice (31.6 vs. 3.0%; P < 0.01) was also observed. Thus older mice with Gs alpha overexpression exhibit many of the features of dilated cardiomyopathy. This study supports the concept that chronic sympathetic stimulation over an extended period of time, i.e., over the life of an animal, is deleterious and actually may result in cardiomyopathy.

Animals↗
PubMed1997

Effects of a novel inotropic agent, BAY y 5959, in conscious dogs: comparison with dobutamine and milrinone.

Traditional inotropic agents, e.g., those that increase myocardial contraction through enhanced cyclic AMP or those that increase contractility at a relatively high O2 cost are frequently not useful in the clinical setting. Accordingly, newer agents that operate through different mechanisms have been synthesized. The goal of the present study was to compare the effects of a new Ca2+ promotor, BAY y 5959, with more traditional inotropic agents, dobutamine and milrinone, in 11 conscious dogs chronically instrumented for measurement of left ventricular (LV) and arterial pressures, LV internal diameter, wall thickness, coronary blood flow, and arterial and coronary sinus O2 content. Equi-inotropic doses of BAY y 5959 (20 microg x kg(-1) x min(-1)), dobutamine (10 microg x kg(-1) x min(-1)), and milrinone (10 microg x kg(-1) x min(-1)) were selected, which increased the LV rate of pressure development in sinus rhythm by 71-78% from similar baselines. Heart rate rose with dobutamine (+24 +/- 4%) and milrinone (+23 +/- 2%) but fell with BAY y 5959 (-35 +/- 3%). Dobutamine increased myocardial O2 consumption (MV(O2)) by 88 +/- 10%. In contrast, MV(O2) increased less with BAY y 5959 (+9 +/- 3%) and milrinone (+16 +/- 5%; P < 0.05). Furthermore, mechanical efficiency was also calculated either with direct measurement of cardiac output or by pressure-volume loops. Dobutamine and milrinone did not change efficiency; however, BAY y 5959 increased efficiency by 19 +/- 5%. With the heart rate held constant, BAY y 5959 increased MV(O2) by 32 +/- 4% but still increased efficiency by 28 +/- 7%. Thus the Ca2+ promotor BAY y 5959 has unique features that might be desirable for clinical applications where inotropic support is indicated, but increased MV(O2) without enhanced mechanical efficiency is deleterious.

Animals↗
PubMed1997

Automatic Gene Recognition without Using Training Data.

In this paper, we propose a new approach for gene recognition, which uses no training data for the recognizer. In this approach, we start from a simple model, which only uses the knowledge of start codons and the stop codons, then the recognition of the DNA sequences by the recognizer and the training of the parameters of the recognizer by the result of the recognition are repeated. We applied this parse and train approach to the complete genome sequence of cyanobacterium, and achieved the almost same recognition rate with the case of using the whole sequence as training data. This results open the possibility to use automatic gene annotation system in the early stage of sequencing projects.

Journal Article↗
PubMed1997

A new plug-in software architecture applied for a portable molecular structure browser.

A new software configuration method using plug-in style components was established for the tool with the incremental development of software used in protein structural study. Our memory database provides the interface of data and functions among plug-in modules and its host program. A molecular structure browser program was developed together with several plug-in modules on our programming library that maintains graphics portability and user interfaces. This plug-in software architecture is generally useful for large-scale software development and for prototyping parts of the system.

Computer Graphics↗
PubMed1997

[A epidemiologic study on the prevalence of the allergic diseases in school children in Kyoto City].

UNLABELLED: The prevalence of allergic diseases in school children in Kyoto City (17,906 children) was examined with the questionnaire which was prepared by the Study Group of Epidemiology of Allergic Diseases funded by the Ministry of Public Welfare in 1993. RESULTS: 1) The number of valid reply was 16,176 (reply rate 90.3%). The reply rate of each question was from 89.5% to 98.9% (average 95.7%). 2) The prevalence of bronchial asthma was 4.9% in the elementary school children, 3.5% in the junior high school children and 4.5% in total, and the prevalence in boys was higher than girls (ratio 1.6). The prevalence of wheezing was 6.5%, 2.7% and 5.5%, respectively, and the sex ratio was 1.2. 3) The prevalence of atopic dermatitis was 5.3% in elementary school children, 4.0% in junior high school children and 5.0% in total, and the prevalence in boys was lower than girls (ratio 0.87). 4) The prevalence of allergic rhinitis was 19.8% in elementary school children, 21.2% in junior high school children and 20.3% in total, and the prevalence in boys was higher than girls (ratio 1.3). 5) The prevalence of allergic conjunctivitis was 11.9% in elementary school children, 15.4% in junior high school children and 13.0% in total and the prevalence in boys was almost same as girls (ratio 0.98). 6) The prevalence of any allergic diseases was 32.2% in elementary school children, 31.7% in junior high school children and 32.1% in total and the prevalence in boys was higher than girls (ratio 1.2).

Adolescent↗