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Biomedical subjects

M Katayama

Publications and source records attributed to M Katayama.

At least 253 records · Page 14Linked to original sources
PubMed1988

Biodistributions of radioactive alkaline metals in tumor bearing animals: comparison with 201Tl.

The retention values for 42K, 86Rb and 134Cs in the tissues and blood were quite similar to those for 201Tl, but were very different from those for 22Na. In an experiment for subcellular fractionation of tumors, most of these nuclides were localized in the supernatant fraction, with small amounts in other fractions. The concentration ratios for these nuclides in each fraction were approximately constant regardless of the time after administration. Radioactive alkaline metals in the supernatant fraction of the tumor homogenate existed mostly as free ions and were bound to protein in other fractions of tumor tissue. These results were essentially the same as those for 201Tl. Ouabain suppression studies indicated that 201Tl is taken up into the tumor cells partly through Na+, K+-ATPase of their membranes. Ionic radii of alkaline metals and thallium were related to their blood and tumor retention values. This relationship suggested that monovalent cations whose ionic radii exceed 0.133 nm, and which exist as free ions in the tissue fluids, behave like the potassium ion. Potassium and K analogs (Tl, Rb, Cs) are avidly taken up into viable tumor cells whose Na+, K+-ATPase activity is elevated. Therefore, suitable radionuclides of K and K analogs can be excellent agents for visualization of viable tumor tissues.

Animals↗
PubMed1988

Isomagnetic maps in right ventricular overloading.

Isomagnetic maps were recorded in normal subjects and in patients with systolic overloading of the right ventricle. The isomagnetic maps examined in this study indicated the instantaneous current source of the heart by applying the "corkscrew rule." The magnetic field recorded by a second derivative gradiometer detected clearly the cardiac current source from the right ventricle, which is located close to the anterior chest wall, and improved diagnostic sensitivity. Moreover, the isomagnetic map showed multiple dipoles, which are difficult to detect in the electrocardiogram or isopotential map. These results suggest that the magnetocardiogram provides useful information on current sources to supplement information obtained by the conventional electrocardiogram.

Adult↗
PubMed1988

Analysis of the T wave of the magnetocardiogram in patients with essential hypertension by means of isomagnetic and vector arrow maps.

Magnetocardiograms (MCGs) of 50 normal subjects and 40 patients with essential hypertension were recorded to determine the value of the MCG for detecting abnormal repolarization. Among the patients with essential hypertension, there were nine cases (22.5%) in whom isopotential maps did not show rightward repolarization vectors but isomagnetic and vector arrow maps showed a rightward repolarization vector in some areas in addition to the normal repolarization vector. Departure maps of the ECG showed an increased repolarization vector directed anteriorly in some of these cases. The repolarization abnormality was recognized in only the MCG departure map in four cases, while no case showed abnormality in only the ECG departure map. With the progress of hypertension, the repolarization abnormality was seen more frequently and its detection using the MCG was higher than that using the ECG. Furthermore, multiple dipoles were detected more frequently from the MCG than from the ECG. Thus the MCG seems more useful than the ECG in the analysis of repolarization abnormalities in essential hypertension.

Adult↗
PubMed1988

Identification of a protein factor and the nucleotide sequence required for processing of mouse precursor rRNA.

We have studied the protein components and nucleotide sequence involved in the endonucleolytic cleavage at 105 bp upstream of the 5' end of mouse 18S rRNA. By fractionating the mouse S100 extract into four fractions by phosphocellulose chromatography, we separated and characterized the processing factor which participated in in vitro coupled and uncoupled transcription-processing systems. Processing activity was recovered in the flow-through fraction (fraction A), while the transcription initiation was supported by the combination of fractions C and D. This endonucleolytic cleavage activity was heat-labile and resistant to micrococcal nuclease. By constructing deletion fragments, we found that the sequence between 219 bp upstream and 26 bp downstream of the processing site was required for the processing. This sequence does not include the 18S rRNA coding region and can form a stem-loop secondary structure.

Animals↗
PubMed1988

Isolation, physico-chemical properties and biological activity of pamamycin-607, an aerial mycelium-inducing substance from Streptomyces alboniger.

Pamamycin-607, which showed aerial mycelium-inducing activity, has been isolated from Streptomyces alboniger IFO 12738. At 0.1 microgram/disc it induces aerial mycelia in the aerial mycelium-negative strain of S. alboniger but inhibits growth of the substrate mycelia at 10 micrograms/disc. It also acts as an antibiotic against some fungi and bacteria. When KMnO4 was partitioned with pamamycin-607 between benzene and water, MnO4- but no K+ was transferred from the water to the benzene layer; pamamycin-607 was thus shown to be a novel anion-transfer antibiotic.

Anti-Bacterial Agents↗
PubMed1988

Neurothekeoma.

Neurothekeoma is a rare, benign cutaneous tumor with a fairly distinctive histologic appearance and characteristic clinical features. A second typical case of neurothekeoma in Japan, occurring on the dorsal aspect of the right hand, is presented.

Adult↗
PubMed1988

[Pharmacokinetic, bacteriological and clinical studies of ceftizoxime in neonates].

Pharmacokinetic, bacteriological and clinical studies of ceftizoxime (CZX) were performed in neonates. 1. Serum concentrations and urinary excretion of CZX were investigated in 12 neonates ranging ages from 1 to 27 days (gestational age, 35-41 weeks; birth weight, 2,150-4,030 g) and 2 infants ranging ages from 55 to 57 days (gestational age, 39-40 weeks; birth weight, 2,320-2,650 g). Each of the subjects was given a single intravenous dose of 20 mg/kg by one shot. Serum concentrations of CZX in the neonates were 24.9-53.7 micrograms/ml at 1/4 hour after intravenous injection, with an average of 40.6 +/- 7.6 micrograms/ml. Serum half-lives of CZX were 1.32-4.75 hours and averaged 2.60 +/- 1.06 hours. Serum concentrations ranged from 2.01 to 14.6 micrograms/ml at 6 hours after injection with an average of 7.70 +/- 3.89 micrograms/ml. In the 2 infants, serum concentrations were 42.0 and 46.2 micrograms/ml at 1/4 hour (average: 44.1 +/- 3.0 micrograms/ml), and 2.91 and 5.04 micrograms/ml at 6 hours after injection (average: 3.98 +/- 1.51 micrograms/ml). Half-lives were 1.54 hours in 1 infant and 1.93 hours in the other (average: 1.74 +/- 0.28 hours). Furthermore, 6-hour urinary recovery rates were 28.5-71.7% (average: 49.3 +/- 12.8%) in the neonates and 42.1-55.5% (average: 48.8 +/- 9.5%) in the infants. The above results suggest that the following 3 points are accepted; 1) peak serum concentrations (at 1/4 hour) in neonates were similar to those in infants and older children irrespective of age (days after birth). 2) Serum half-lives of CZX in neonates shortly after birth were 4 or 5 times longer than those in older children, but decreased rapidly with the advance of day-ages. The half-life in neonates of 2 weeks of age or so became shorter to about twice the normal value in infants. Furthermore, half-lives of the drug in those at an age of the first half of infancy were similar to those in older children. 3) The urinary excretion rates tended to be somewhat low with neonates soon after birth, but became very similar to those in infants and older children at a relatively early stage.(ABSTRACT TRUNCATED AT 400 WORDS)

Bacterial Infections↗
PubMed1988

[Studies of rokitamycin in pediatrics].

Pharmacokinetic, bacteriological and clinical studies on a new macrolide antibiotic, rokitamycin (RKM) dry syrup for pediatric use, were done, and results as summarized below were observed: 1. Five children with ages between 6 and 10 years were administered orally with RKM at a dose level of 10 mg/kg either at 30 minutes before or 30 minutes after meal on a crossover design, and plasma concentrations and urinary excretion rates of the drug were measured. Plasma concentrations of RKM following the administration before meal were 0.50 microgram/ml at 1/2 hour, 0.43 microgram/ml at 1 hour, 0.15 microgram/ml at 2 hours, 0.03 microgram/ml at 4 hours, and not detectable at 6 hours. Plasma concentrations following the administration after meal were 0.11 microgram/ml at 1/2 hour, 0.15 microgram/ml at 1 hour, 0.09 microgram/ml at 2 hours, 0.03 microgram/ml at 4 hours, and not detectable at 6 hours. The 0-6 hour urinary recovery rates were 1.41% following the administration before meal, and 0.93% following the administration after meal. These results suggested that the drug might be absorbed more rapidly, giving a higher plasma concentration, when administered before meal than when administered after meal. Changes in plasma concentrations of RKM following the administration of 10 mg/kg before meal were similar to those of two 100 mg RKM tablets (TMS-19-Q.GC tablets) to adult patients. Therefore, it seemed optimal to administer 10 mg/kg 3 times daily at fasting to children as a rule.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗
PubMed1988

The twitcher mouse. An alteration of the unmyelinated fibers in the PNS.

The twitcher is an authentic murine model of globoid cell leukodystrophy (GLD) in man. Extensive demyelination of the central and peripheral nervous systems (CNS and PNS) characterizes the neuropathologic features of GLD. In the common peroneal nerve of the twitcher, where demyelination was extensive, pronounced morphologic and quantitative alterations were noted in the unmyelinated fibers. They were 1) a large number of long and attenuated cellular processes of Schwann cells, which often enclosed only one or two axons; and 2) a threefold increase in the number of Schwann cell-axon units with reduced numbers of axons per unit. These results suggested increased branching of unmyelinated Schwann cells. Mild increase in unmyelinated fibers and mild decrease in myelinated fibers were additional features. In contrast, the sympathetic nerve trunk, which had only small numbers of myelinated and rare or no demyelinated fibers, showed much milder alterations in the unmyelinated fibers. Thus, the results of our study suggest that the alterations of the Schwann cells of the unmyelinated fibers in the twitcher are secondary to or in association with the chronic demyelinating process.

Animals↗
PubMed1988

[Pharmacokinetic and clinical evaluations on ceftriaxone in neonates].

1. Ten neonates 0 to 28 days old (gestation: 37-42 weeks; birth weight: 2,160-3,640 g) received 20 mg/kg CTRX (8 cases) or 10 mg/kg (2 cases) by intravenous bolus injection, while 9 infants 35 days to 9 months old (gestation: 37-43 weeks; birth weight: 2,800-3,560 g) received 20 mg/kg by intravenous bolus injection, and their blood drug concentrations and urinary drug excretions were examined. Average blood levels of CTRX in the 20 mg/kg dosage group were 114 +/- 14.6 micrograms/ml at 30 minutes, 109 +/- 12.8 micrograms/ml at 1 hour, 100 +/- 12.6 micrograms/ml at 2 hours, 87.9 +/- 15.8 micrograms/ml at 4 hours, 72.8 +/- 15.3 micrograms/ml at 6 hours, and 50.1 +/- 12.3 micrograms/ml at 12 hours in the neonates; and 113 +/- 20.0 micrograms/ml at 30 minutes, 101 +/- 14.7 micrograms/ml at 1 hour, 83.6 +/- 9.3 micrograms/ml at 2 hours, 70.3 +/- 10.7 micrograms/ml at 4 hours, 56.9 +/- 8.6 micrograms/ml at 6 hours, and 35.7 +/- 9.2 micrograms/ml at 12 hours in the infants. Average half-lives of CTRX in blood were 10.3 +/- 4.5 hours in the neonates, and 6.6 +/- 1.9 hours in the infants. Average blood concentrations of CTRX in the 10 mg/kg dosage neonate group were 63.8 +/- 6.0 micrograms/ml at 30 minutes, 57.8 +/- 2.5 micrograms/ml at 1 hour, 53.5 +/- 0.7 micrograms/ml at 2 hours, 41.8 +/- 7.4 micrograms/ml at 4 hours, 32.4 +/- 5.9 micrograms/ml at 6 hours, and 20.8 +/- 1.1 micrograms/ml at 12 hours, and the half-life was 7.2 +/- 0.4 hours. These results suggest that blood concentrations are apparently dose-related in the neonate period; that the peak levels of the neonate and infant groups were similar (the levels at 30 minutes) not showing a relationship to age, gestation period or to birth weight; and that the higher the age was the shorter the half-life became with the half-life in the one week old group was 1.5 times as long as that in the older infant group. The half-life in the younger infant group, however, was similar to that in the older infant group. Urinary excretion was examined in 4 neonates and 2 infants. Average urinary recovery rates in 12 hours after intravenous injection were 40.8 +/- 8.3% in the neonate group and 44.8 +/- 12.8% in the infant group, showing that CTRX is excreted well even in the neonate period.(ABSTRACT TRUNCATED AT 400 WORDS)

Bacterial Infections↗