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Biomedical subjects

K Murayama

Publications and source records attributed to K Murayama.

At least 199 records · Page 11Linked to original sources
PubMed1982

[The changes of human plasma ACTH and immunoreactive beta-endorphin during spontaneous or oxytocics induced/maintained labor and delivery (author's transl)].

To evaluate the effects of oxytocics on ACTH and Immunoreactive (IR)-beta-endorphin release, concentrations of these hormones in the plasma of 22 women during spontaneous labor, 22 women in labor who had received oxytocin and 19 women in labor who had received PG.F2 alpha at the time of vaginal delivery, were measured. Maternal ACTH and IR-beta-endorphin concentrations were elevated during spontaneous or oxytocics induced/maintained labor and peaked immediately after delivery and decreased two hours later. There were significant correlations between ACTH and IR-beta-endorphin concentrations during spontaneous labor and delivery (r = 0.921, p less than 0.0001), as well as in oxytocin or PG.F2 alpha induced/maintained labor and delivery (r = 0.833, r = 0.916, p less than 0.0001, respectively). The concentrations of ACTH and IR-beta-endorphin during PG-F2 alpha infusion were slightly higher than those seen in the other two types of labor. However, there was no significant difference in the levels of ACTH and IR-beta-endorphin among the three types of labor. Simultaneous maternal and umbilical cord plasma samples were obtained in 25 cases at delivery. However, there was no significant correlation between ACTH or IR-beta-endorphin concentrations in paired samples. These results suggest that 1) IR-beta-endorphin is secreted in parallel with ACTH, into the peripheral blood by the maternal pituitary gland in response to the stress of labor during all types of labor and delivery; 2) there is no significant difference in the response of ACTH and IR-beta-endorphin between spontaneous and oxytocics induced/maintained labor and delivery: 3) ACTH and IR-beta-endorphin in cord blood are not of maternal origin.

Adrenocorticotropic Hormone↗
PubMed1981

Determination of glutamic acid and gamma-aminobutyric acid in Ringer's solution without desalination at the femtomole level by gas chromatography chemical ionization mass spectrometry.

For the quantification of glutamic acid in Ringer's solution, pentafluoropropionic methyl ester was the most sensitive derivative. The detectable concentration was 0.01 microM glutamic acid in Ringer's solution; the amount of the preparation was 1 pmol and the injection into a gas chromatograph mass spectrometer was 10 fmol. For the quantification of gamma-aminobutyric acid in Ringer's solution, the trifluoroacetal-hexafluoropropionyl ester was quantification of gamma-aminobutyric acid in Ringer's solution, the trifluoroacetal-hexafluoropropionyl ester was detectable at a concentration of 0.01 microM. Ringer's salts facilitated acylation in the order heptafluorobutyric anhydride greater than pentafluoropropionic anhydride greater than trifluoroacetic anhydride. The effect depended on esterification of carboxy groups in the order methyl ester greater than hexafluoropropionyl ester greater than butyl ester. Sodium carbonate, sodium acetate and sodium citrate also facilitated acylation with pentafluoroproionic anhydride, while sodium phosphate inhibited the acylation and sodium sulfate inhibited it slightly. The pentafluoropropionic methyl ester of glutamic acid was stable for up to 10 days, when it was dissolved in acetone and stored at -18 degrees C.

Gas Chromatography-Mass Spectrometry↗
PubMed1980

Primary localized amyloidosis of bladder.

A case of primary localized amyloid tumor of the bladder is described, which was confused with neoplasm by cystoscopic, urographic, and other studies. Surgical specimens obtained by transurethral resection were diagnostic.

Aged↗
PubMed1980

Biochemical and immunological characterizations of rat pepsinogens and pepsins.

Biochemical and immunological properties of two kinds of pepsinogens isolated from the gastric mucosal extracts of adult Wistar rats were studied. Their activated enzymes were prepared from the zymogens using a DEAE-Sepharose CL-6B column. The isoelectric points of pepsinogens I and II were estimated to be 3.90 and 3.75, respectively, by isoelectric focusing, and those of pepsins I and II to be 3.60 and 3.45, respectively. Amino acid compositions of the two pepsinogens or pepsins were strikingly similar to each other and neither pepsinogen I nor II contained organic phosphate. The biochemical properties of rat preparations compared with porcine pepsinogens A and C and pepsins A [EC 3.4.23.1] and C [EC 3.4.23.3] showed that rat pepsinogens and pepsins resembled porcine pepsinogen C and pepsin C, respectively. Pepsinogens I and II were demonstrated to share a similar immunogenic molecular structure by double diffusion analysis and Laurell immunoelectrophoresis. Rabbit antipepsinogen I serum cross-reacted with the mouse preparation but did not with the rabbit and porcine preparations. The possibility of the genetically controlled occurrence of pepsinogens I and II in the rat is discussed.

Amino Acids↗
PubMed1980

The interaction between the effects of insulin and ouabain on the activity of Na transport system in frog skeletal muscle.

The effects of insulin and ouabain on 22Na efflux and net Na loss were examined in frog sartorius muscles. After removal of ouabain, 22Na efflux which had been inhibited by ouabain remained at the inhibited level for more than 2 hr. In ouabain-free solution, insulin stimulated the Na efflux from ouabain-preincubated muscles. The stimulating effect of insulin on 22Na efflux was completely blocked by the presence of ouabain. Insulin shifted the Na efflux vs. intracellular Na concentration relationship toward the region of lower Na concentrations, and made the slope of log (Na efflux) vs. log [Na]1 relationship less step. On the other hand, ouabain shifted the Na efflux vs. intracellular Na concentration relationship toward the region of higher Na concentration, and made the slope of the log (Na efflux) vs. log [Na]1 relationship steeper. The relationship between insulin-stimulated Na efflux and intracellular Na concentration obtained from ouabain-preincubated muscle was located in the region of higher Na concentrations than that obtained from control muscle. These findings suggest that insulin increases an apparent affinity of binding sites for Na ions, and the possibility that insulin increases the Vmax of Na transport system may be excluded. In contrast with the effect of insulin, ouabain may be considered to decrease the apparent affinity of binding site for Na ions.

Animals↗
PubMed1980

Effects of ouabain on Na efflux in high internal Na and insulin-preincubated muscles.

To gain an insight into the mechanism of stimulation by insulin of Na efflux, the effect of high concentrations of internal Na on the inhibition by ouabain of Na efflux was compared to the inhibition by ouabain of insulin-stimulated Na efflux. The rate coefficient of 22Na efflux from "high-Na" muscle exposed to ouabain was lower than that from "low-Na" muscle exposed to ouabain. Similarly, the rate of net Na loss from the "high-Na" muscle which had been exposed to ouabain was lower than that frm the "low-Na" muscle. These findings indicate that Na transport units whose internal Na-binding sites have been occupied by Na is susceptible to ouabain. The insulin-stimulated Na efflux was inhibited by ouabain to a larger extent than was the Na efflux from the control muscle, although the final level of the rate coefficient of 22Na efflux from the muscle exposed to both insulin and ouabain was not always lower than that from the muscle exposed only to ouabain. The similarity between the effects of ouabain in "high-Na" muscle and in insulin-preincubated muscle suggests that insulin increases the fraction of Na transport units whose internal Na-binding sites have been occupied by Na.

Animals↗
PubMed1980

Apparent affinity changes induced by insulin of Na-K transport system in frog skeletal muscle.

The dependency of Na efflux on intracellular Na concentration was examined on sartorius muscles of Rana catesbeiana. In normal Ringer, the rate coefficient of 22Na efflux is nearly proportional to the internal Na concentration, i.e., Hill's coefficient in the dependency of Na efflux on internal Na concentration was around two. As long as insulin is present in the bathing solution, the rate coefficient of 22Na efflux retains the stimulated level. Insulin caused a leftward shift of the relationship between Na efflux and the logarithm of internal Na concentration, and concomitantly decreased Hill's coefficient. A model of the coupling of Na transport and hydrolysis of ATP was proposed. The theoretical relation derived from this model accounted for these findings quite satisfactorily. According to this model, insulin shifts as a cofactor the equilibrium between dephosphorylated and phosphorylated states of carriers, whose Na binding sites are not occupied by Na, toward the phosphorylated state.

Animals↗
PubMed1977

Some electrical properties of the membrane of the barnacle muscle fibers under internal perfusion.

Intracellular perfusion technique has been applied to the muscle fibers of the barnacle species, Balanus nubilus. In these fibers, generation and the form of the calcium spike was governed by the frequency of stimulation and intra- and extracellular calcium concentrations. Voltage-clamp experiments showed that the magnitude of the potassium outward current was controlled by the intracellular calcium concentration whose increase, nearly 10(3)-fold, raised the resting membrane conductance and the outward potassium current. On the other hand, application of 10 mM zinc ions inside the muscle fiber had no effect on either the resting potential or the outward potassium current but suppressed the early inward calcium current. Similarly, the inward calcium current was decreased by low concentration of sodium ions in the extracellular fluid only when its ionic strength was made low by substituting sucrose for the sodium salt. Measurement of outward current with the muscle fiber in calcium-free ASW solution and intracellularly perfused with several cationic solutions established the selectivity sequence TEA less than Cs less than Li less than Tris less than Rb less than Na less than K for the potassium channel.

Action Potentials↗
PubMed1977

Circulatory effects of magnesium sulfate in normotensive and renal hypertensive pregnant sheep.

We have studied the effects of magnesium sulfate (MgSO4) administration in chronically instrumented normotensive and hypertensive pregnant sheep. Animals of 90 to 144 days' gestation were divided in two groups; those with normotensive arterial pressure and those in which renovascular hypertension had been produced. Our results show that bolus injection of 2 or 4 Gm. of MgSO4 caused a transient decrease in systolic and diastolic pressure which returned to control values within 5 to 10 minutes. The continuous infusion of MgSO4 in doses of 2 or 4 Gm. per hour produced a slight increase in uteroplacental blood flow but did not alter the blood pressure. Heart rate showed a slight increase. Because MgSO4 produced no significant hemodynamic changes, we feel that: (1) its use in obstetrics must be based on its anticonvulsant action and (2) MgSO4 in either normotensive or hypertensive patients is not associated with impairment of uteroplacental blood flow.

Animals↗