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Biomedical subjects

F Watanabe

Publications and source records attributed to F Watanabe.

At least 235 records · Page 13Linked to original sources
PubMed1987

1H NMR study of degradation mechanisms of oxacephem derivatives with various 3'-substituents in alkaline solution.

The degradation process of oxacephems with various 3'-substituents in alkaline solution was examined by 1H NMR spectroscopy, and the structures of two types of degradation products were determined: the hydrolysis products having the cleaved beta-lactam ring and the remaining 3'-substituents, and the exo-methylene compounds having the cleaved beta-lactam ring and the expelled 3'-substituents. The oxacephems were found to decompose, giving the former compounds that subsequently decomposed to the latter compound. Although the ratios of the formation of the exo-methylene compound 15 relative to the other degradation products depended on the leavability of the 3'-substituents, there was little correlation between the relative yields and the beta-lactam reactivity. Thus, the expulsion of the leaving group at the 3'-position was concluded to be not involved in the nucleophilic attack on the beta-lactam carbonyl.

Cephalosporins↗
PubMed1987

An epithelioma of the ciliary body.

A 57-year-old woman developed a ciliary body mass which compressed the anterior side of the lens with focal cataract causing the iris to protrude into the anterior chamber. The lesion was removed by a large iridocyclectomy. The mass was classified as an epithelioma of the ciliary body, which was consistent with a benign epithelioma, i.e. an adenoma of the nonpigmented ciliary epithelium. Light and electron microscopic examinations revealed that the tumor cells had characteristics of both the ciliary and iris epithelium, which originated from the neuroectoderm, including abundant cytoplasmic filaments, and pheomelanosomes, and that the gland-like lumen was the pseudoacinous lumen, i.e. invaginated stroma containing the vitreous.

Adenoma↗
PubMed1987

[Experimental study on myocardial protection by means of retrograde coronary sinus cooling perfusion (RCSP) during aorto-coronary bypass surgery].

Cold chemical cardioplegia by the antegrade method is a useful, widely employed procedure for protecting the myocardium in aorto-coronary by pass surgery. Perfusion of a cardioplegic solution into the ischemic area is, however, insufficient in the presence of a severe lesion in the coronary artery, leading to postoperative cardiac hypofunction. We performed an experimental study using RCSP, which lessens this problem, in the excised dog heart. Hearts excised from 20 dogs were assigned to normal coronary artery groups (group I consisting of the hearts from 5 dogs and a perfusion solution temperature of 20 degrees C, group II consisting of the hearts from 5 dogs and a temperature of 30 degrees C) and blocked coronary artery groups (group III consisting of the hearts from 5 dogs and a temperature of 20 degrees C, group IV consisting of the hearts from 5 dogs and a temperature of 30 degrees C). RCSP was undertaken for two hours with a new modified Krebs solution. Hemodynamic and myocardial metabolic parameters during a given work load under fixed conditions and heart beat after reopening of the blood flow using our original function circuit were compared between the experimental groups and a control group (consisting of normal hearts studied immediately after excision from 5 dogs not given myocardial protection). In the group with normal coronary arteries, LVW and LV dp/dt were better in group I than in group II throughout the course; these values were significantly lower in group II than in the control group, but there was no significant difference between group I and the control group. These parameters were also improved in group III (with blocked coronary arteries), but there was no significant difference in improvement between group III and the control group 60 minutes after reperfusion. In group IV, on the other hand, improvement was poor. The myocardial metabolic parameters also showed approximately the same results. These results suggested that RCSP with the new modified Krebs' solution at perfusion temperature of 20 degrees C afforded effective protection of the myocardium for two hours. From the fact that a favorable protective effect of the myocardium was obtained in group III, as in group I, RCSP was considered to provide a useful procedure for protection of the myocardium in aorto-coronary bypass for severe or wide-ranging coronary artery diseases.

Animals↗
PubMed1986

Biosynthesis of porcine kidney D-amino acid oxidase.

The biosynthesis of a porcine kidney peroxisomal enzyme, D-amino acid oxidase (EC 1.4.3.3., DAO), was investigated. Pig kidney mRNA as well as free and membrane-bound polysomes were used to investigate in vitro protein synthesis using a rabbit reticulocyte lysate. mRNA and free polysomes, but not membrane-bound polysomes, directed the synthesis of DAO. To examine the in vivo synthesis of the enzyme, a pig kidney cell line (LLC-PK1) was biosynthetically labelled. Both the in vitro and in vivo synthesized DAO had the same molecular weight, 38,000, as that of the purified enzyme. These results indicate strongly that DAO is synthesized on free ribosomes and transferred to the interior of peroxisomes without any proteolytic modification.

Animals↗
PubMed1986

Cooperative interaction of histone H1 with DNA.

The cooperative binding of histone H1 with DNA was studied using a fluorescently labelled histone H1. The titration data were analysed in terms of the large ligand model. The stoichiometric number, n = 65 +/- 10 bases/H1, was independent of NaCl concentration (0.02 - 0.35 M). The nucleation and the cooperative binding constants, K' and K, and the cooperativity parameter q were sensitive to salt concentration; K = 3.6 +/- 0.8 X 10(7) M-1 and q = 1.1 +/- 0.4 X 10(3) at 0.2 M NaCl. The dependence of K' on NaCl concentration revealed that 6 Na+ ions were released from DNA upon complex formation. An extrapolation of K' to 1M NaCl yielded a small value, K' = 5 +/- 2 M-1. Thus the binding of H1 is essentially electrostatic, being compatible with its independence of temperature. A calculation of K' based on the counterion release reproduced the salt concentration dependence of K'. Therefore, the binding of H1 is of an electrostatic territorial type. Thus, H1 may move along the DNA chain to a certain extent, when both salt concentration and the degree of saturation are sufficiently low. The condition is so restricted that the sliding would not play an important role in vivo. It was concluded from the DNA concentration independent binding isotherm that H1 can cooperatively bind onto a single DNA molecule. A simple power law dependence of the cooperativity parameter q upon NaCl concentration was found; q oc[NaCl]h with h = 0.72, though the physical basis of this dependence remains unknown.

Animals↗
PubMed1985

[Enzyme immunoassay for serum 18-hydroxycorticosterone and its clinical application].

An enzyme immunoassay for serum 18-hydroxycorticosterone was established using alkaline phosphatase as a label. The antiserum for 18-hydroxycorticosterone was produced by immunization of rabbits with 18-hydroxycorticosterone 3-(o-carboxymethyl) oxime conjugated to bovine serum albumin. Sephadex LH-20 column chromatography was used to separate 18-hydroxycorticosterone from other steroids in serum samples. The minimal detectable amount of 18-hydroxycorticosterone was 50 pg/tube, and the measurable range was from 5 to 1000 ng/dl when a 1.0 ml serum sample was used. Intra- and inter-assay coefficients of variance were 5.0% (n = 6), and 5.8% (n = 6), respectively. In normal controls the serum 18-hydroxycorticosterone level was 4.8 approximately 34.0 ng/dl (mean +/- S.D. = 17.1 +/- 9.0 ng/dl) on an unrestricted diet. Seven out of 8 patients with aldosterone-producing adenoma had above-normal serum 18-hydroxycorticosterone levels. Serum 18-hydroxycorticosterone increased and decreased significantly following ACTH and dexamethasone administration, respectively. In essential hypertensive patients, serum 18-hydroxycorticosterone was high during a low-sodium diet and was suppressed remarkably by captopril. These observations support the previous reports that adrenal 18-hydroxycorticosterone synthesis is dependent on both ACTH and the renin-angiotensin system. The present method is sufficiently sensitive and producible, avoids the use of radioisotopes and is quite satisfactory for clinical use.

18-Hydroxycorticosterone↗
PubMed1985

Energy-independent protection of the oxidative phosphorylation capacity of mitochondria against anoxic damage by ATP and its non-metabolizable analogs.

Preservation of the oxidative phosphorylation capacity of mitochondria by addition of ATP under anaerobic conditions was analyzed by use of non-metabolizable adenine nucleotide analogs. The capacity was well preserved in the presence of ATP and did not require the hydrolysis of ATP, since ATP analogs, such as beta, gamma-methylene adenosine triphosphate (AMPPCP), alpha, beta-methylene adenosine triphosphate (AMPCPP), and adenylyl imidodiphosphate (AMPPNP), were as effective as ATP. These analogs were incorporated into mitochondria through ATP/ADP translocase to maintain the original level of total adenine nucleotides in the mitochondria. ADP apparently had the same effect as ATP, but its effect was shown to be due to ATP generated from it by adenylate kinase in mitochondria. An analog of ADP, alpha, beta-methylene adenosine diphosphate (AMPCP), which was found to be a substrate of the translocase but not of adenylate kinase, could not replace ADP or ATP. From these results, it was concluded that the oxidative phosphorylation capacity of mitochondria was maintained by ATP, but not ADP, through a process not requiring energy.

Adenosine Diphosphate↗
PubMed1985

Correlation between cellular ATP level and bile excretion in the rat liver.

The influence of the cellular level of adenosine triphosphate (ATP) in the liver on bile excretion was studied in rats. In ischemia, the cellular ATP level decreased rapidly--and, concomitantly, bile flow stopped within 5 min. Administration of L-ethionine i.p. to rats reduced the bile flow rate with decrease in the cellular ATP level. The correlation between the bile flow rate and the cellular ATP level was confirmed in a liver perfusion system. On anoxic perfusion, the ATP level and bile flow rate changed in the same manner as in ischemia. The recovery rates of both on reoxygenation decreased with increase in the anoxic perfusion period. During perfusion under oxygenated conditions, decrease in cellular ATP to various levels by infusion of various concentrations of potassium cyanide, an inhibitor of respiration, resulted in corresponding and concomitant suppression of bile excretion. Kinetic analysis of the bile flow rate revealed a Michaelis-Menten-type curve for the cellular ATP level. The apparent Kms for ATP of bile flow rate in L-ethionine-treated rat liver and liver perfused with potassium cyanide were 1.0 and 1.6 mM, and their Vmax values were 4.1 and 2.5 microliter/min/g liver, respectively. The concentrations of main bile components, such as phospholipids, cholesterol, and taurocholate increased, but their total outputs decreased with decrease in the ATP level, and returned to the normal range with recovery of the ATP level. Thus, it was shown experimentally that the extent of hepatic injury can be assessed simply by monitoring the bile flow rate, which reflects the cellular level of ATP.

Adenosine Triphosphate↗