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Biomedical subjects

K Miki

Publications and source records attributed to K Miki.

At least 271 records · Page 15Linked to original sources
PubMed1993

Dissociation of catecholamine and corticosterone responses to different types of stress in rats.

To examine hormonal response patterns to various stresses, urinary excretion of catecholamines and corticosterone was measured in spontaneously hypertensive rats (SHR) and Wistar-Kyoto normotensive rats (WKY) under the following conditions: immobilization, restriction to a small space, introduction of new rats, and noise exposure. In WKY rats, immobilization caused a marked increase in urinary corticosterone, adrenaline and noradrenaline and a decrease in dopamine excretion. Restriction to a small space induced a less pronounced but still obvious increase in adrenaline and corticosterone and a decrease in dopamine. When other rats were introduced into the animal room, the senior rats showed an increase in adrenaline alone, while noise exposure produced an increase in corticosterone alone. These findings suggest that while severe stress, such as immobilization, causes marked changes in all 4 hormones, relatively mild stress produces changes in one to three, not all, hormones, and that catecholamine and corticosteroid responses are dissociated in some forms of the mild stress. It is considered that neuroendocrine responses to stress vary according to both the type of stress and its intensity. In SHR rats, the hormone response to severe stress was greater than in WKY rats, and the response was somewhat less than in WKY rats when exposed to mild stress. These findings do not imply that stress-induced hyperactivity of sympathetic adrenomedullary system participates in the development of hypertension in SHR rats.

Animals↗
PubMed1993

Cardiovascular responses to upright tilt at a simulated altitude of 3,700 m in men.

To examine the effects of high altitude on cardiovascular responses to orthostasis, 11 healthy males were tested at a 10-min passive 70 degrees head-up tilt at sea level and at a simulated high altitude of 3,700 m. During the control period in the supine position, heart rate and forearm blood flow were higher at high altitude (p < 0.05). Mean arterial pressure remained unchanged during head-up tilt at sea level, but it reduced from 82 mm Hg to 72 mm Hg (p < 0.05) during head-up tilt at high altitude. There were no altitude-related changes in the magnitude of the increase in forearm vascular resistance and the reduction in cardiac output and laser-Doppler skin blood flow in response to head-up tilt. The total peripheral resistance increased from 14.4 to 20.5 mm Hg.L-1 x min-1 (p < 0.05) during head-up tilt at sea level, but the change was not significant at high altitude. The lack of altitude-related changes in forearm vascular resistance and laser-Doppler skin blood flow during head-up tilt in the presence of attenuated total peripheral resistance response at high altitude may suggest that the orthostatic hypotension at high altitude is associated with a lower magnitude of vasoconstrictor response in the regions other than the limbs and the skin.

Adult↗
PubMed1992

Tissue- and cell-specific control of guinea pig cathepsin E gene expression.

Northern blotting of RNAs from normal guinea pig tissues revealed that the tissue distribution of cathepsin E mRNA was relatively limited and the highest level of the mRNA was observed in the stomach mucosa. Expression of the mRNA was also observed in the spleen, although the level was very low. These results were in good agreement with the distribution of the cathepsin E-producing cells as revealed by immunohistochemistry. In the separated fractions of dispersed mucosal cells prepared from the stomach by centrifugal elutriation, the extent of cathepsin E mRNA expression was closely correlated with the enrichment of the producing cells. In addition, both CCGG and GCGC sites within the gene region were hypomethylated to a greater extent in the producing tissues than elsewhere, reflecting specific hypomethylation in the producing cells. The observed tissue- and cell-specific transcriptional control of cathepsin E gene, which is correlated with a decreased level of methylation in the gene region, suggests that the enzyme is probably involved in specific functions of particular differentiated cells, especially those of the stomach mucosa.

Animals↗
PubMed1992

Gastric procathepsin E and progastricsin from guinea pig. Purification, molecular cloning of cDNAs, and characterization of enzymatic properties, with special reference to procathepsin E.

Procathepsin E and progastricsin were purified from the gastric mucosa of the guinea pig. They were converted to the active form autocatalytically under acidic conditions. Each active form hydrolyzed protein substrates maximally at around pH 2.5. Pepstatin inhibited cathepsin E very strongly at an equimolar concentration, whereas the inhibition was much weaker for gastricsin. Molecular cloning of the respective cDNAs permitted us to deduce the complete amino acid sequences of their pre-proforms; preprocathepsin E and preprogastricsin consisted of 391 and 394 residues, respectively. Procathepsin E has unique structural and enzymatic features among the aspartic proteinases. Lys at position 37, which is common to various aspartic proteinases and is thought to be important for stabilizing the activation segment, was absent at the corresponding position, as in human procathepsin E. The rate of activation of procathepsin E to cathepsin E is maximal at around pH 4.0. It is very different from the pepsinogens and may be correlated with the absence of Lys37. Native procathepsin E is a dimer, consisting of two monomers covalently bound by a disulfide bridge between 2 Cys37. Interconversion between the dimer and the monomer was reversible and regulated by low concentrations of a reducing reagent. Although the properties of the dimeric and monomeric cathepsins E are quite similar, a marked difference was found between them in terms of their stability in weakly alkaline solution: monomeric cathepsin E was unstable at weakly alkaline pH whereas the dimeric form was stable. The generation of the monomer was thought to be the process leading to inactivation, hence degradation of cathepsin E in vivo.

Amino Acid Sequence↗
PubMed1992

Detection of anti-gag antibodies of feline immunodeficiency virus in cat sera by enzyme-linked immunosorbent assay.

Using gag protein of feline immunodeficiency virus (FIV) expressed in Escherichia coli, an enzyme-linked immunosorbent assay (ELISA) system was developed for detection of antibodies to FIV gag protein in cat sera. With serum samples from cats experimentally infected with several strains and an infectious molecular clone of FIV, increases of the antibody titers to FIV gag protein were observed in all cases by the ELISA at early stage of infection. When we examined a total of 415 field cat sera which were previously tested by an indirect immunofluorescence assay (IFA), 9 (12.9%) out of 70 IFA positive sera were judged as negative by the ELISA. However, all 3 serum samples tested among the 9 IFA positive sera had antibodies to gp130 but not to p26 by a radioimmunoprecipitation assay. The results indicated that some IFA positive sera did not have antibodies to the p26 though they have antibodies to other proteins specific for FIV.

Animals↗
PubMed1992

Molecular characterization and heterogeneity of feline immunodeficiency virus isolates.

We have molecularly cloned the complete genomic DNA of TM2 strain of feline immunodeficiency virus (FIV) isolated in Japan and compared its nucleotide and the deduced amino acid sequence with those of previously described U.S. isolates, FIV Petaluma and FIV PPR. The infectious molecular clone of FIV TM2 is different from FIV Petaluma in host cell range; the clone can not infect Crandell feline kidney cells which were permissive for FIV Petaluma. The amino acid sequence homologies, in gag, pol, and env genes between FIV TM2 and Petaluma were 90%, 87%, and 81%, respectively. On the other hand, comparative analysis of each gene between FIV Petaluma and PPR showed 96,95, and 85%, respectively. These results suggested that the genomic diversity was present among FIV strains isolated from geographically distant areas. Interestingly, tat- and rev-like short open reading frames contained inframe stop codons in the FIV Petaluma but not in the FIV TM2.

Amino Acid Sequence↗
PubMed1992

Expression of feline immunodeficiency virus gag gene in Escherichia coli.

The gag gene of a Japanese feline immunodeficiency virus (FIV) isolate, designated as FIV TM 2, was expressed in Escherichia coli as a fusion protein with TrpE. Using this expressed protein, an enzyme-linked immunosorbent assay was developed for detection of antibodies to FIV gag protein in feline sera. With serum samples from a cat experimentally infected with FIV, it was demonstrated that the period of seroconversion detected by this method corresponded to that by Western blotting.

Cloning, Molecular↗
PubMed1992

Relationship of Helicobacter pylori to serum pepsinogens in an asymptomatic Japanese population.

A seroepidemiologic study of the prevalence of Helicobacter pylori infection in Japan was performed, and the relationship between serum pepsinogen I and II levels (markers of gastritis and gastric atrophy) and H. pylori infection was investigated. Four hundred and eighteen asymptomatic children and adults were studied. The prevalence of anti-H. pylori immunoglobulin G antibody increased with age. For persons born after 1950, the frequency of H. pylori infection increased at approximately 1% per year; for those born before 1950 the prevalence was high (70%-80%) and relatively constant. Serum pepsinogen I and II levels were significantly higher in H. pylori-infected volunteers than in H. pylori-uninfected volunteers [51.6 +/- 3 vs. 42.9 +/- 2 ng/mL (P less than 0.05) for pepsinogen I; 16.0 +/- 1 vs. 7.5 +/- 0.8 ng/mL (P less than 0.001) for pepsinogen II]. The ratio of pepsinogen I to pepsinogen II was significantly lower in H. pylori-infected volunteers (3.5 +/- 0.2) than in uninfected volunteers (6.3 +/- 0.3; P less than 0.001). The apparent decrease in prevalence of H. pylori accompanying the Westernization of Japan may eventually be accompanied by a reduction in the frequency of atrophic gastritis, the precursor lesion of the epidemic form of gastric carcinoma, and ultimately result in a decrease in the incidence of gastric carcinoma in Japan.

Adolescent↗
PubMed1992

Histogenesis of human stomach cancers based on assessment of differentiation.

The histogenesis of human stomach cancer was assessed based on the determination of the differentiation of component cancer cells. Specimens of 229 surgically obtained primary gastric cancers were used. Histochemical staining of mucins [paradoxical concanavalin A, galactose oxidase-Schiff (GOS), and sialidase-GOS sequence] and immunohistochemical demonstration of pepsinogens (Pg) I and II allowed the differentiation of gastric elements including mucous neck cells, pyloric gland cells, and surface mucous cells as well as intestinal goblet and absorptive cell types. Of 122 papillary and tubular adenocarcinomas, the proportion consisting mainly of intestinal type cells increased with progression from 22.9% (early) to 41.9% (advanced). Similarly, intestinal features increased with progression from 8.3% (early) to 25.4% (advanced) in the 107 poorly differentiated adenocarcinomas, signet ring cell carcinomas, and mucinous adenocarcinomas studied. A phenotypic shift from gastric- to intestinal-type expression was thus observed with progression of each histologic type of gastric cancer. Furthermore, tumors consisting mainly of gastric-type cells were commonly found within intestinal metaplastic mucosa, suggesting that this latter is not a preneoplastic lesion for gastric cancers in humans.

Adult↗
PubMed1992

Electrotransfection of protoplasts from tomato, wild tomato, barley and chrysanthemum with tobacco mosaic virus RNA.

Protoplasts isolated from tomato, wild tomato, barley and chrysanthemum were electrotransfected with tobacco mosaic virus (TMV) RNA under almost the same optimum electric conditions: five square DC pulses of 50 microseconds duration at 500 to 800 V/cm, with the protoplasts suspended at 2 x 10(5)/ml in 0.5 M-mannitol containing 100 microM-MgCl2 and 10 to 20 micrograms/ml TMV RNA. ELISAs of these transfected protoplasts showed that the yields and the growth curves of the virus were quite similar, indicating a lack of host specificity in the initially infected cells of these plants.

Chrysanthemum cinerariifolium↗
PubMed1992

Expression and characterization of glycoprotein gp35 of hepatitis C virus using recombinant vaccinia virus.

Complementary DNA clones corresponding to one of the putative structural regions of the hepatitis C virus (HCV) genome were obtained from sera of non-A non-B hepatitis patients. The putative envelope gene was expressed by using a recombinant vaccinia virus carrying this region of the HCV genome. In cells infected with the recombinant vaccinia virus, a glycosylated protein with an M(r) of about 35K (gp35) was specifically detected by convalescent sera from hepatitis C patients. The sera from rabbits immunized with this recombinant vaccinia virus reacted to the gp35 produced in insect cells and also to gp35 which was translated in vitro in the glycosylated and processed form. The gp35 was used to detect antibodies in sera of only 7 to 23% of HCV patients at various stages of HCV disease. These results suggest that the gp35 of HCV may not have high antigenicity in humans.

Amino Acid Sequence↗
PubMed1992

Alteration of type II regulatory subunit of cAMP-dependent protein kinase in human cisplatin-resistant cells as a basis of collateral sensitivity to 8-chloro-cAMP.

A cyclic adenosine 3',5'-monophosphate (cAMP) analogue, 8-chloro-cAMP (8-Cl-cAMP), had a collateral growth-inhibitory effect on a cis-diamminedichloroplatinum(II) (CDDP)-resistant human cancer cell lines (PC-14/CDDP). The non-selective analogues dibutyryl-cAMP, 8-bromo-cAMP and forskolin, which are cAMP agonists, showed far less cytotoxicity than 8-Cl-cAMP in both cell lines. There was no significant difference in cAMP content between PC-14 and PC-14/CDDP. Because 8-Cl-cAMP has been shown to bind selectively to the site I receptor of the type II regulatory subunit (RII) of cAMP-dependent protein kinase, we determined the level of expression of regulatory subunits in PC-14 and PC-14/CDDP cells by photoaffinity labeling. PC-14/CDDP cells had a higher RII level, low site I receptor of type I regulatory subunit (RI) level, and a lower RI/RII ratio than the parental PC-14 cells. Exposure to 8-Cl-cAMP increased the RI and RII level in PC-14/CDDP cells in dose- and time-dependent manners. On the other hand, in parental PC-14 cells, RII was not detected and the levels of RI and RII were not increased by exposure to 8-Cl-cAMP. These results suggested that the change in RI and/or RII levels caused by 8-Cl-cAMP was correlated with 8-Cl-cAMP-induced growth inhibition and that the collateral sensitivity to 8-Cl-cAMP in CDDP-resistant cells was due to the increased RII level. Our results suggest that 8-Cl-cAMP can be used in combination with CDDP and that measurement of RI and RII levels and/or the RI/RII ratio is a useful tool to predict CDDP sensitivity.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed1992

Effect of dehydration on thirst and drinking during immersion in men.

The mechanism for reduced voluntary water intake during water immersion was studied in eight men (19-25 yr of age) immersed to the neck while sitting for 3 h at 34.5 degrees C or in air at 28 degrees C when euhydrated (Eu-H2O and Eu-air, respectively) and hypohydrated (Hypo-H2O and Hypo-air) by 3.6% body weight loss. Thirst sensations (degree of thirst, mouth dryness and taste, drinking desirability, and stomach fullness) were similar at the beginning of Hypo-air and Hypo-H2O test periods. Initial drinking of tap water (15 degrees C) was 216 +/- 30 ml/7 min (P less than 0.05) with Hypo-air, decreased to 108 +/- 28 ml/7 min (P less than 0.05) with Hypo-H2O, and was 10-50 ml/10-30 min thereafter. Intake was less than 10 ml/10-30 min in Eu-air, and there was no drinking in Eu-H2O. Within the first 10 min of immersion, compared with Hypo-air findings, the significant reduction in drinking in the Hypo-H2O experiment was associated with unchanged plasma Na+, plasma osmolality, heart rates, and mean arterial pressures; the different responses were increased cardiac output, plasma volume, and atrial natriuretic peptides and decreased plasma renin activity and arginine vasopressin. Thus the extracellular pathway, as opposed to the osmotic pathway, appears to be the major mechanism for immersion-induced suppression of drinking.

Adult↗
PubMed1992

Performance of an enzyme-linked immunosorbent assay system for antibodies to hepatitis C virus with two new antigens (c11/c7).

We developed an enzyme-linked immunosorbent assay (ELISA) system for antibodies to the hepatitis C virus (HCV), using two new recombinant antigens (c11 and c7) derived from the HCV genome. The performance of this ELISA system (Imucheck HCV Ab) was examined. The CV values for both intra-assay precision and reproducibility of identifying HCV antibody in the panel sera ranged from 3.5% to 6.4%. The blood elements in serum and anticoagulants did not interfere in this ELISA system. The specificity of Imucheck HCV Ab to samples from patients with non-A, non-B (NANB)-type chronic hepatitis, liver cirrhosis, and hepatocellular carcinoma was 93.7%, 93.5%, and 81.4%, respectively. These results are more sensitive than those obtained by the first-generation anti-HCV ELISA system. In the samples from patients with NANB-type acute hepatitis, Imucheck HCV Ab enabled detection of HCV antibodies at an early stage. This system increased the sensitivity for blood donor screening and for monitoring patients with acute hepatitis.

Antibody Specificity↗
PubMed1992

[Typing of methicillin-resistant Staphylococcus aureus by antibiotic resistance phenotypes as an epidemiological marker in nosocomial infections].

A total of 129 clinical isolates of methicillin-resistant Staphylococcus aureus was tested for the susceptibility to 28 antibiotics, antiseptics and heavy metal salts, according to the method of Gillespie et al. The strains showed resistance ranging from 20% to 80%, to 10 agents, such as amikacin, chloramphenicol, clindamycin, gentamicin, neomycin, streptomycin, tobramycin, acriflavine, cadmium nitrate, ethidium bromide. These agents were finally chosen for typing in this study. Strains resistant to 10 agents were distributed into 55 phenotypes. Most strains isolated from one ward belonged to the specified phenotype, whereas strains isolated from other wards were divided into a variety of phenotypes. It seemed to be the occurrence of nosocomial infection in this hospital. This typing method gives the merit to be easy, economical, rapid and reproducible for the epidemiological investigations in the clinical bacteriological laboratory.

Anti-Bacterial Agents↗
PubMed1992

Cardiovascular responses to upright tilt in man during acute exposure to 3 atm abs air.

To examine the effect of acute hyperbaric exposure on cardiovascular response to orthostasis, a passive 70 degrees head-up tilt (HUT) test was performed for 15 min in a simulated compressed-air hyperbaric environment of 3 atm abs at ambient temperature of 31 degrees C (thermoneutral) on 8 male subjects. Heart rate (HR), blood pressure, cardiac output (CO) by impedance cardiography, forearm blood flow (FBF) by the occlusion plethysmography, and laser-Doppler skin blood flow (BFLD) on the thigh were measured for 15 min before, during, and after HUT. Esophageal temperature and HR data were recorded continuously. An identical test was performed in a 29 degrees C (thermoneutral) normal atmospheric condition. None of the subjects showed signs of syncope during HUT in either environment. Baseline HR was significantly lower (P less than 0.05) at 3 atm abs, and the increase in HR (delta HR) during HUT was of the same magnitude (15 beats/min) at both atmospheric pressures. The reduction of systolic blood pressure (delta SBP) was identical in both environments. Thus, the chronotropic response to HUT (delta HR/delta SBP) was the same. A marked reduction in CO (P less than 0.05) was attributed to a reduction of stroke volume during HUT, and the reduction was greater (P less than 0.05) at 3 atm abs. There were no pressure-dependent changes during HUT in FBF, forearm vascular resistance, and BFLD except for a greater increase (P less than 0.05) in total peripheral resistance at 3 atm abs. These observations suggest that orthostatic tolerance was maintained in the presence of lower CO at 3 atm abs, probably by a greater vasoconstrictor response in the splanchnic areas. We conclude that the substantial bradycardia which occurred at 3 atm abs did not interfere with a normal response to orthostasis in humans because of a peripheral vasoconstriction caused by the elevated oxygen pressure and an enhanced increase in total peripheral resistance which occurred during HUT in 3 atm abs.

Adult↗
PubMed1991

Purification, characterization, and amino acid sequences of pepsinogens and pepsins from the esophageal mucosa of bullfrog (Rana catesbeiana)

Two pepsinogens (pepsinogens 1 and 2) were purified from the esophageal mucosa of the bullfrog (Rana catesbeiana), and their molecular weights were determined to be 40,100 and 39,200, respectively, by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The NH2-terminal 70-residue sequences of both pepsinogens are the same, including the 36-residue activation segment. Furthermore, a cDNA clone encoding frog pepsinogen was obtained and sequenced, which permitted deduction of the complete amino acid sequence (368 residues) of one of the pepsinogen isozymogens. The calculated molecular weight of the protein (40,034) coincided well with the values obtained by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. These results are incompatible with the previous report (Shugerman R. P., Hirschowitz, B. I., Bhown, A. S., Schrohenloher, R. E., and Spenney, J. G. (1982) J. Biol. Chem. 257, 795-798) that the major pepsinogen isolated from the bullfrog esophageal gland is a unique "mini" pepsinogen with a molecular weight of approximately 32,000-34,000. The two pepsinogens were immunologically indistinguishable from each other and related to human pepsinogen C. The deduced amino acid sequence was also more homologous with those of pepsinogens C than those of pepsinogens A and prochymosin. These results indicate that the frog pepsinogens belong to the pepsinogen C group. They were both glycoproteins, and therefore, this is the first finding of carbohydrate-containing pepsinogens C. Both pepsinogens were activated to pepsins in the same manner by an apparent one-step mechanism. The resulting pepsins were enzymatically indistinguishable from each other, and their properties resembled those of tuna pepsins.

Amino Acid Sequence↗