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Biomedical subjects

A Kono

Publications and source records attributed to A Kono.

At least 109 records · Page 6Linked to original sources
PubMed1984

The use of left ventricular end-ejection pressure and peak pressure in the estimation of the end-systolic pressure-volume relationship.

The end-systolic pressure-volume relationship (ESPVR) as derived from left ventricular pressure-volume loops has gained increasing acceptance as an index of ventricular contractile function. In animal experiments the ESPVR has been defined as a line connecting the upper left corners of several differently loaded pressure-volume (P-V) loops with a slope parameter Ees and a volume axis intercept parameter Vo. In the clinical setting, several variants of the ESPVR have been determined with use of peak left ventricular pressure, end-ejection pressure, and end-ejection volume. The maximum P-V ratio has also frequently been measured. We attempted to determine which of these alternatives resulted in good approximations of the reference ESPVR in eight isolated canine ventricles that ejected into a simulated arterial impedance system with resistance, compliance, and characteristic impedance. We determined various versions of the ESPVR from the same set of beats quickly obtained with little change in inotropic background. To vary ventricular pressure wave forms, each of the arterial impedance parameters was independently controlled at 50%, 100%, and 200% of normal. Against each of the nine combinations of the impedance parameters four P-V loops were obtained under four preloads and from each of the sets of four P-V loops, the reference ESPVR, linear regression of the peak pressure on end-ejection volume (ESPVRPP-EEV), and linear regression of end-ejection pressure on end-ejection volume (ESPVREEPV) were determined. In addition, the maximum P-V ratio (MPVR) was calculated for each P-V loop.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1984

[Measurement of 5'-deoxy-5-fluorouridine (5'-DFUR) by high-performance liquid chromatography and studies on pharmacokinetics of 5'-DFUR and 5-fluorouracil by oral and intravenous administration].

The authors have made clear that 5'-deoxy-5-fluorouridine (5'-DFUR), a derivative of 5-fluorouracil (5-FU), is activated by thymidine phosphorylase with has a particularly high activity in human malignant tumors. This derivative therefore, has fewer side-effects and can be expected to produce a greater antitumor effect when administered to cancer patients. Blood levels of 5'-DFUR and 5-FU were then observed with time after oral or intravenous 5'-DFUR administration in order to study its clinical effect. First, a method for measurement of 5'-DFUR and 5-FU was devised using high-performance liquid chromatography (HPLC). The results obtained using this method revealed that for intravenous administration both 5'-DFUR and 5-FU showed rapid drops in blood level while for oral administration both showed blood level peaks after one hour which were maintained of the same level for two hours, decreasing gradually thereafter. 5-FU showed a blood level peak after one hour, decreasing gradually thereafter. From the above results it was proved that a relatively high percentage of orally administered 5'-DFUR was absorbed from the intestine.

Administration, Oral↗
PubMed1983

[Enzymatic conversion of tegafur in human tumor tissue].

Enzymatic conversion of tegafur was studied using a thymidine phosphorylase preparation purified from human liver cancer. Tegafur dissolved in water slowly decomposed to 5-FU upon storage at 37 degrees C and this conversion was further activated with an addition of a thymidine phosphorylase preparation. Analysis of Tegafur and 5-FU was performed on a high performance liquid chromatograph. The Km value was in agreement with Michaelis-Menten Kinetics and 2.44 X 10(-2) M without thymidine phosphorylase preparation. When the preparation was added, it was 2.53 X 10(-4) M and 1.75 X 10(-3) M, respectively. Determination of 5-FU concentrations in blood, normal and tumor tissues following a long term administration of Tegafur was performed. The highest concentration of 5-FU was detected in tumor tissue followed by normal tissue and blood, suggesting a human liver thymidine phosphorylase was capable of converting Tegafur to 5-FU more actively in tumor tissue than in normal tissue.

Adult↗
PubMed1983

Isolation and pathogenicity of provisional serovar 1621-54 of "Shigella" from imported cynomolgus monkeys.

The provisional serovar 1621-54 of "Shigella" was isolated from 36 (13.2%) of 273 cynomolgus monkeys newly imported into Tsukuba Primate Center for Medical Science (TPC) from Indonesia during the period from 1980 through 1981. The biochemical properties of the isolates were in good agreement with those of previously described provisional "Shigella" serovar 1621-54. Clinically, 13 (36.1%) of 36 monkeys being positive for the organisms excreted diarrheal stools on arrival at TPC. In addition, the organisms were isolated also from three other monkeys contracting dysentery during the quarantine period at TPC. One of them died 2 days after the onset of dysentery. Histopathological findings of this case were essentially the same as those of Shigella-infected monkeys. Pathogenicity of the isolates was examined in three experimental infection models; (1) the infection model using cultured HeLa-S3 cells, (2) the keratoconjunctival infection model of the guinea pig, and (3) the intestinal infection model of the cynomolgus monkey. All the strains tested showed positive results in these experimental models, causing intracellular penetration and multiplication in HeLa-S3 cell cultures, keratoconjunctivitis in guinea pigs, and dysentery in cynomolgus monkeys. These results indicate that provisional "Shigella" serovar 1621-54 is a causative agent of dysentery in man as well as in monkeys.

Animals↗