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Biomedical subjects

M Yamaguchi

Publications and source records attributed to M Yamaguchi.

At least 1,567 records · Page 87Linked to original sources
PubMed1985

Arterial blood gases fail to reflect acid-base status during cardiopulmonary resuscitation: a preliminary report.

The American Heart Association's current standards for CPR indicate that acid-base therapy should be guided by measurements of arterial blood gases. However, we have discovered a striking discrepancy between arterial and venous blood gases during CPR: severe venous hypercarbia and acidosis may coexist with simultaneous arterial alkalosis. Arterial blood gases during CPR, therefore, may not accurately reflect the acid-base status of mixed venous blood and thus may fail to indicate systemic acid-base status.

Acid-Base Equilibrium↗
PubMed1985

Penetration and clearance of cefoperazone and moxalactam in pleural fluid.

The penetration of cefoperazone and moxalactam into pleural fluid was studied in 11 patients after intravenous infusion of 2-g doses of these agents. Clearance of these agents from pleural fluid was studied in seven patients after instillation of 1-g doses into the pleural space. The concentrations in pleural fluid after intravenous infusion of 2-g doses reached a peak of 7 to 25 micrograms/ml for cefoperazone and 9 to 35 micrograms/ml for moxalactam at 4 to 6 h after administration. These levels exceeded reported MICs for most susceptible organisms. The elimination half-life of both agents was about two to five times longer in pleural fluid than in serum. These prolonged elimination rates of both agents might be of great advantage for killing bacteria in the pleural space.

Aged↗
PubMed1985

DNA primase-DNA polymerase alpha from simian cells: sequence specificity of initiation sites on simian virus 40 DNA.

Unique single-stranded regions of simian virus 40 DNA, phage M13 virion DNA, and several homopolymers were used as templates for the synthesis of (p)ppRNA-DNA chains by CV-1 cell DNA primase-DNA polymerase alpha. Intact RNA primers, specifically labeled with an RNA capping enzyme, were typically 6 to 8 ribonucleotides long, although their lengths ranged from 1 to 9 bases. The fraction of intact RNA primers 1 to 4 ribonucleotides long was 14 to 73%, depending on the template used. RNA primer length varied among primers initiated at the same nucleotide, as well as with primers initiated at different sites. Thus, the size of an RNA primer depended on template sequence. Initiation sites were identified by mapping 5' ends of nascent RNA-DNA chains on the template sequence, identifying the 5'-terminal ribonucleotide, and partially sequencing one RNA primer. A total of 56 initiation events were identified on simian virus 40 DNA, an average of 1 every 16 bases. Some sites were preferred over others. A consensus sequence for initiation sites consisted of either 3'-dCTTT or 3'-dCCC centered within 7 to 25 pyrimidine-rich residues; the 5' ends of RNA primers were complementary to the dT or dC. High ATP/GTP ratios promoted initiation of RNA primer synthesis at 3'-dCTTT sites, whereas low ATP/GTP ratios promoted initiation at 3'-dCCC sites. Similarly, polydeoxythymidylic acid and polydeoxycytidylic acid were the only effective homopolymer templates. Thus, both template sequence and ribonucleoside triphosphate concentrations determine which initiation sites are used by DNA primase-DNA polymerase alpha. Remarkably, initiation sites selected in vitro were strikingly different from initiation sites selected during simian virus 40 DNA replication in vivo.

Adenosine Triphosphate↗
PubMed1985

Pulmonary blood volume and pulmonary extravascular water volume in men.

In order to estimate the pulmonary blood volume between the pulmonary artery trunk and the left atrium (PBV PAT-LA), simultaneously with the pulmonary extravascular water volume (PEWV) in the chronically stable cardiac patients, we employed the double indicator dilution method using heat as a diffusible indicator and indocyanine green as a non-diffusible indicator. The PEWV was obtained as the extravascular lung thermal volume estimated in the aortic root (LTVAo). In the group of hemodynamically normal patients, in spite of ischemic heart disease (G-N, n = 22), the mean pulmonary artery wedge (PAW) pressure was 9.3 +/- 3.9 mmHg (mean +/- SD), PBVPAT-LA was 8.95 +/- 1.71 ml/kg, LTVAo was 5.71 +/- 1.37 ml/kg and PBVPAT-LA/LTVAo ratio was 1.64 +/- 0.44. In the group of hemodynamically slightly compromised patients with mitral stenosis (G-MS, n = 13), the mean PAW pressure was 14.2 +/- 2.6 mmHg, PBVPAT-LA was 11.12 +/- 2.86 ml/kg, LTVAo was 5.68 +/- 1.41 ml/kg and PBVPAT-LA/LTVAo ratio was 2.02 +/- 0.58. Between the two groups, LTVAo was not statistically significant, whereas the mean PAW pressure, PBVPAT-LA and PBVPAT-LA/LTVAo ratio were all significantly increased in G-MS (p less than 0.05). Neither PBVPAT-LA nor LTVAo correlated with the mean PAW pressure in both groups. From PBVPAT-LA/LTVAo ratio, fluid volume in the intravascular space was greater than that in the extravascular space in both groups. From LTVAo, PEWV in G-MS was identical with that in G-N, in spite of the elevated mean PAW pressure. Therefore, even in the patients with mitral stenosis, the interstitium in the lung is kept "dry" under conditions of the mean PAW pressure below 20 mmHg. The safety factors that prevent pulmonary edema, as evidenced in animal studies, seem to operate effectively in man.

Blood Volume↗
PubMed1985

Regulation of (Ca2+-Mg2+)-ATPase activity by calcitonin binding to rat liver plasma membranes.

The plasma membranes isolated from rat liver bound 125I-labelled ([125I]) synthetic [Asu1,7]eel calcitonin (CT), with increasing concentrations of [125I]CT. This specific binding was completely saturated at a concentration of 0.5 nM CT. A high affinity Ca2+-stimulated, Mg2+-dependent ATPase [(Ca2+-Mg2+)-ATPase] activity in the plasma membranes was significantly decreased by the presence of a very low concentration of CT (7.4 pM), although the hormone did not affect the activity of the plasma membrane 5'-nucleotidase. The concentration of CT needed for maximal inhibition of (Ca2+-Mg2+)-ATPase in the plasma membranes was less than 0.74 nM. The plasma membranes washed with 10(-3)% digitonin did not show an inhibitory effect of CT on (Ca2+-Mg2+)-ATPase activity, while the reagent did not have a significant effect on the enzyme. These results suggest that the inhibition of (Ca2+-Mg2+)-ATPase activity may be part of the mechanism by which CT elevates cytosolic Ca2+ in liver cells.

Angiotensin II↗
PubMed1985

Participation of Ca2+ channel in liver calcium regulation by calcitonin in rats.

A possible regulatory role of calcitonin (CT) upon liver calcium content was investigated by using a Ca2+ channel blocker in thyroparathyroidectomized (TPTX) rats. In bile duct-ligated TPTX rats, liver calcium content was not significantly increased by a single ip injection of calcium chloride (4.0 mg Ca2+/100 g body weight). Administration of CT (80 MRC mU/100 g) caused a remarkable elevation of liver calcium content. This hormonal effect was inhibited by administration of verapamil (1.0 mg/100 g) or lanthanum chloride (0.4 mg/100 g), Ca2+ channel blockers. CT administration markedly increased the transport of calcium into the bile through the liver cells of TPTX rats injected ip with calcium. This increase in the bile calcium content was prevented by administration of verapamil or lanthanum chloride. Administration of epinephrine (10 micrograms/100 g), vasopressin (10 micrograms/100 g), or concanavalin A (1.0 mg/100 g) produced a significant elevation of bile calcium content; these elevations were not significantly altered by addition of verapamil (1.0 mg/100 g). These data suggest the presence of CT receptors on liver cell plasma membranes which are involved in regulation of membrane Ca2+ channels. It is proposed that CT facilitates the entry of extracellular calcium into liver cells by opening Ca2+ channels located on their plasma membranes.

Animals↗
PubMed1985

Studies on exercise and an elastic protein "connectin" in hindlimb muscle of growing rat.

We examined the effect of physical training on the properties of an elastic protein, connectin, in the hindlimb muscles of 6 growing rats running on a treadmill, in comparison with its properties in 6 growing non-running rats. The experimental results are as follows. 1) The body weight of exercised (R-) and control (C-) rats gradually increased during housing for 31 days, from an average of 46.2 g to 275 g. The average amount of running in the 6 R-rats was 38,160 +/- 12,122 (S.D.) g X m/hr. 2) The SDS-insoluble connectin in R-rat muscle was lower in quantity than that in C-rat muscle, but the SDS-soluble connectin of R-rat muscle was greater in quantity. 3) Amino acid compositions of SDS-soluble connectin in R- and C-rats, calculated from SDS-insoluble connectin and soleus ghost, were significantly different. 4) The soleus ghost preparation consisted mainly of connectin as shown by SDS polyacrylamide gel electrophoresis and by immunohistological staining. 5) The maximum passive tension of the soleus ghost, calculated from the factors of T/phi and (dT/dx)/phi, was higher in R-rats than in C-rats. The above results suggest that physical training might alter the biosynthetic pattern of connectin to suit the developing muscle, just as physical training alters that of myosin isoenzymes.

Amino Acids↗
PubMed1985

[The effect of population growth on the economic development of Japan].

The author reviews research supporting and opposing the Malthusian view that the effect of population growth on per capita income in Japan has been negative. Distinguishing between total population growth and the growth of the labor force, the author finds that "over the total period (1880-1970) population cum labor growth on average tended to make a positive contribution to per capita income growth." (summary in ENG)

Asia↗
PubMed1985

Increase in DNA polymerase alpha in nuclei of chicken kidney cells after avian adenovirus infection.

DNA polymerase activity which sedimented at about 7s in the presence of 0.5M KC1 increased in cultured kidney cells after infection with a chicken embryo lethal orphan virus, an avian adenovirus. Elevated levels of antigenic material to a monoclonal antibody specific for the large subunit of chicken DNA polymerase alpha were also detected in nuclei of virus-infected cells by an immunofluorescence method. Since the elevations of DNA polymerase activity and of nuclear immunofluorescence was not inhibited with 1-beta-D-arabinofuranosylcytosine, the early viral gene(s) seems to be responsible for the induction of the synthesis and nuclear accumulation of DNA polymerase alpha.

Adenoviridae Infections↗
PubMed1985

Effect of photooxidation on catalytic and regulatory properties of NAD-linked malic enzyme from Escherichia coli.

In an aim to elucidate the structure-function relationship of NAD-linked malic enzyme [EC 1.1.1.38] from Escherichia coli W, the effect of chemical modification on the catalytic and regulatory properties of the enzyme was studied. Upon photooxidation of the enzyme in the presence of methylene blue, a time-dependent inactivation occurred following pseudo-first order kinetics. The pH-dependence of the inactivation rate exhibited a pK value of 6.1. L-Malate, NAD+, and Mn2+ markedly protected the enzyme against the inactivation. Prior masking of the catalytically essential sulfhydryl groups with p-mercuribenzoate did not result in a retardation of the rate of photoinactivation. This excluded the possibility of an involvement of sulfhydryl group modification in the photoinactivation. Although the Km values for L-malate and NAD+ were not affected by photooxidation, the S0.5 value and the Hill coefficient for Mn2+ were considerably altered, and the cooperative nature of the saturation profile for Mn2+ in the native enzyme was completely abolished. The activating effect of L-aspartate on the native enzyme was completely abolished upon photooxidation, and the inhibitory effect of CoA was also diminished to a marked extent upon the treatment. The oxaloacetate decarboxylating activity of the enzyme was lost in parallel with the loss of the activity for oxidative decarboxylation of L-malate. These results suggest a possible involvement of histidyl residue(s) in the catalytic and regulatory functions of the enzyme.

Escherichia coli↗
PubMed1985

[Assessment of the combined effects of mitomycin C with alpha-interferon or gamma-interferon by the clonogenic assay technique].

The combined effects of Mitomycin C (MMC) with alpha-interferon (HLBI) or gamma-interferon (TRP-2), which have become attractive drugs for use as Biological Response Modifiers, were investigated using the human tumor clonogenic assay technique. Tumors in this study were five human tumor xenografts serially transplanted into nude mice (three gastric cancer, two colon cancer). When the survival fraction occurring with the combination was smaller than that obtained by multiplication of the survival fractions occurring with either drug alone, the combined effect was considered to be synergism. Four out of five xenografts (three gastric cancer, one colon cancer) showed synergistic effects for the combination of MMC with alpha-interferon. Although two gastric cancer xenografts showed synergism for the combination of MMC with gamma-interferon, antagonistic effects were observed in one gastric cancer and one colon cancer xenograft.

Animals↗
PubMed1985

[Comparison of human tumor clonogenic and nude mouse-isotope assays in anticancer-agent sensitivity tests].

Comparative studies between the in vitro human tumor clonogenic assay (HTCA) and our original in vivo method (NM-IA) in which the final evaluation was made with 3H-TdR incorporation of tumor cells transplanted into nude mice were simultaneously performed on 44 fresh human solid tumors (22 gastric cancers, 6 breast cancers, 4 gall bladder cancers, 4 liposarcomas and 8 other tumors). Mitomycin C (MMC), 5-fluorouracil (5-FU), adriamycin (ADM) and cyclophosphamide (CPM) were tested. The evaluable rate was 73% (32/44) in HTCA and 89% (38/44) in NM-IA. Although correlation between the results of HTCA and those of MN-IA was obtained for MMC and ADM, no correlation was observed for 5-FU and CPM.

Animals↗
PubMed1985

[Nuclear magnetic resonance study of brain edema in immature rats compared with adult rats].

Traumatic cerebral edema was experimentally produced in immature Wistar strain rats aged 7 days (Group A), and then edematous cerebrums were lyophilized. The water content was measured by the dry weight method. The longitudinal relaxation time (T1) and transverse relaxation time (T2) were measured on the NMR spectrometer. In respect to the measured water content and the relaxation time, changes with time were compared with those in matured rats aged 5 weeks (Group B). In the Group A, the water contents of the gray matter (G), the white matter (W), and the brain stem (BS) increased significantly over the period ranging from 6 to 16 days after the experimental production of cerebral edema. In the Group B, the water contents of G and W also increased significantly one day after the experimental production of cerebral edema. One day after development of the experimental edema, T1 was 1.770 +/- 0.131 sec (G) and 1.752 +/- 0.131 sec (W) in the Group A, while it was 1.451 +/- 0.003 sec (G) and 1.353 +/- 0.011 sec (W) in the Group B. On the other hand, T2 was 96.95 +/- 11.98 msec (G) and 92.80 +/- 8.78 msec (W) in the Group A, while it was 57.90 +/- 1.32 msec (G) and 58.50 +/- 0.98 msec (W) in the Group B. In other words, the relaxation time was significantly prolonged in the Group A. The extent of the prolongation was insignificant in the Group B considering the base line. T2 is assumed to be divided into two components in the cerebral tissues when cerebral edema develops.(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗