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Biomedical subjects

S Iizuka

Publications and source records attributed to S Iizuka.

At least 55 records · Page 3Linked to original sources
PubMed1989

Inactivation of erythrocyte Cu-Zn-superoxide dismutase through nonenzymatic glycosylation.

Human erythrocyte Cu-Zn-superoxide dismutase undergoes glycation reaction in vitro and in vivo (Arai et al., 1987a; Arai et al., 1987b). In addition, an increase in the glycation of the superoxide dismutase was observed in aged erythrocytes, indicating that the glycation reaction is an age-related change under physiological conditions. In the cases of crude extracts as well as pure enzyme preparations obtained from erythrocytes of patients with Werner's syndrome, the specific activity of the glycated form expressed as units per mg Cu-Zn-superoxide dismutase protein as determined by both enzymatic assay and immunoenzymatic assay was significantly lower and the enzyme was unstable as compared to the normal form.

Adult↗
PubMed1988

Damage of hippocampal neurons caused by cobalt focus in the cerebral cortex of rats.

The relationship between the focus of cobalt seizures in the cerebral cortex and neuron loss in the hippocampus, as well as the CD50 of pentylenetetrazol was examined in rats. Spike activity in EEG frequently appeared 4 days after cobalt application and reached a peak 8-16 days after cobalt application, which was sometimes accompanied by jerks in the limbs. Changes in the CD50 value showed a two-step pattern, i.e., the first decrease in CD50 appeared one day after application of cobalt and continued at the same value until the fourth day. Then a second gradual decrease of CD50 was observed from the fourth day to eighth day and continued at the same value until 20 days after cobalt application. Neuron loss in the CA1 area of the hippocampus was observed as early as two days after cobalt application and the degree of neuron loss progressively increased until the 20th day. These findings suggest that neuron loss in the hippocampus following cobalt-induced seizures is not a result of generalized convulsions.

Animals↗
PubMed1987

Increase in the glucosylated form of erythrocyte Cu-Zn-superoxide dismutase in diabetes and close association of the nonenzymatic glucosylation with the enzyme activity.

Human erythrocytes contain glucosylated and nonglucosylated Cu-Zn-superoxide dismutases which can be separated by boronate affinity chromatography. The percentage of the glucosylated form is significantly increased in the erythrocytes of patients with diabetes as compared to normal erythrocytes. The nonglucosylated form of Cu-Zn-superoxide dismutase, which was washed through the boronate column, was glucosylated in vitro upon exposure to radioactive or non-radioactive D-glucose. Incorporation of D-glucose into the protein was observed, and with the increase in glucosylation, the enzymatic activity decreased, indicating that the glucosylation of the enzyme led to a low active form. This is the first demonstration that superoxide dismutase is glucosylated in erythrocytes and that the glucosylation leads to the inactivation of the enzyme.

Blood Glucose↗
PubMed1987

Characteristics of primary cultured neurons from embryonic mutant El mouse cerebral cortex.

To elucidate the differences between neurons of epileptogenic animals and those of normal animals, cellular characteristics of neurons of mutant strain El mice which are highly susceptible to seizures were investigated using immunocytochemical techniques. In neurons of 3-day primary cultures, the control ddY mouse neurons showed dividing stages in about 0.2% of neurofilament (NF)-positive neurons, whereas no dividing neurons were observed among the NF-positive El mouse neurons. In 7-day cultures, localization of GD3 ganglioside in the proliferating control ddY mouse neurons was observed, but there was no GD3 ganglioside in the mutant El mouse neuron. The content of GD3 ganglioside detected by high-performance thin-layer chromatography of El mouse cultured cells was ca. 1/4 of that of ddy mice. These findings suggest that neurons of the El mouse are differentiated earlier than those of the control ddY mouse.

Animals↗
PubMed1987

Effect of anticonvulsants on pentylenetetrazol-induced power spectrum changes in electroencephalograms in rats.

The effect of anticonvulsants on pentylenetetrazol (PTZ)-induced EEG power spectrum changes was examined. When the minimum dose of PTZ (15 mg/kg) was administered intravenously twice, with an interval of 80 min, a clear EEG power spectrum change was observed after the second PTZ administration, irrespective of whether or not the first PTZ administration evoked marked EEG changes. We defined the values F/N, S/N and S/F. The value F/N, obtained by dividing the power spectrum area after the first PTZ administration by the normal power spectrum area, was 1.06 +/- 0.05 (mean +/- S.E.). The value S/N, obtained by dividing the power spectrum area after the second PTZ administration by the normal power spectrum area, was 2.00 +/- 0.21. The value S/F, obtained by dividing S/N by F/N, was 1.86 +/- 0.16. The S/F value was almost constant regardless of whether or not the first PTZ administration could evoke marked EEG changes. The effect of anticonvulsants was examined by S/F value changes, and 100 mg/kg of PHT completely inhibited the double PTZ effect. Phenobarbital, ethosuximide and sodium valproate also inhibited the double PTZ effect. Using the S/F value of the EEG power spectrum with minimum dose double PTZ administration, quantitative evaluation is possible for anticonvulsant drugs.

Animals↗
PubMed1987

Tissue-dependent expression of two (alpha 1----2)-fucosyltransferases specified by the H and Se genes.

Human blood group H substance is produced from its percursor by the action of (alpha 1----2)-fucosyltransferase. In a classical model, the Se gene that determines secretor status is a regulatory gene controlling the expression of H gene-specified fucosyltransferase in the secretory tissues. However, recent biochemical evidence supports a new genetic model in which the H and Se genes are both structural genes encoding two fucosyltransferases with different characteristics. The H gene-specified enzyme (H enzyme) is absent in secretory tissues and secretory fluids, while the Se gene-specified enzyme (Se enzyme) is missing in hematopoietic tissues. The H enzyme has a much lower Km for phenyl-beta-galactoside than does the Se enzyme. The tissue-dependent expression of the two enzymes was examined according to this criteria. The H enzyme was found to be predominant in the tissues of secretors examined (lung, liver, kidney, stomach, and skeletal muscle). While the Se enzyme exists in the secretor's lung, liver and kidney, very little or none is found in the stomach and skeletal muscle tissues.

ABO Blood-Group System↗
PubMed1986

Purification of Cu-Zn-superoxide dismutase from human erythrocytes by immunoaffinity chromatography. Evidence for the presence of isoelectric heterogeneity.

Cu-Zn-superoxide dismutase (SOD) was prepared in highly purified form from human erythrocytes by immunoaffinity chromatography using anti-human Cu-Zn-SOD goat IgG. The purified SOD had a high specific activity and gave a single band on polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate. On isoelectric focusing and immunoblotting several bands with enzyme activity and antigenicity were discerned.

Chromatography, Affinity↗
PubMed1986

Studies on the human blood group P system: an existence of UDP-Gal:lactosylceramide alpha 1----4 galactosyltransferase in the small p type cells.

Human red blood cells and other tissues with the rare small p type lack all P antigens, and are assumed to be missing key glycosyltransferases in the synthetic pathway of P antigens. Galactosyltransferase activities of the P1 and small p cell extracts were measured using lactosylceramide and GlcNAc as galactose acceptors. The two transferase activities of the small p lymphoblastoid cell extract were comparable to that of the P1 cell extract. The anomeric configuration of the galactosylated lactosylceramide was established by digestion with alpha- and beta-galactosidases, by identification of methylated products, and by staining with the monoclonal antibody against globotriaosyl ceramide (Pk antigen). The results indicate that UDP-Gal:LacCer alpha 1----4 Gal transferase, which produces the Pk antigen from the precursor LacCer, exists in the small p cells. However, intact small p cells could not produce the Pk antigen, and, instead, LacCer was accumulated in the cells. The Pk enzyme appears to be not functional in the small p cells in vivo.

Blood Group Antigens↗
PubMed1986

Clinical application of the perineal scan: prepartum screening for cord presentation.

Real-time linear-array ultrasonographic scanning was performed from the perineum on 12 primiparous term women with the fetus in breech or foot presentation. Scanning was done with the patient initially in lithotomy position and then in semi-Trendelenburg position if a better view was required. The technique appears to be excellent for visualization of the forelaying umbilical cord even when the cervix is closed and is not affected by the acoustic shadow of the public arch. The information obtained by the scanning may be of value in avoiding or improving perinatal mobility of breech/footling fetuses and in providing better perinatal management.

Breech Presentation↗
PubMed1986

Aspects of electrolyte transport across isolated dog retinal pigment epithelium.

Transport of Na and Cl across the isolated dog retinal pigment epithelium (RPE) choroid was investigated. Under the short-circuit condition, a net Na flux was observed from choroid to retina and a net Cl flux was determined in the opposite direction. The current created by the net flux of these two ions was larger than the short-circuit current (SCC). Addition of 10(-5) M ouabain to the apical side inhibited net fluxes of both Na and Cl, whereas it reduced the SCC 84%. Addition of 10(-4) M furosemide to the apical side inhibited net Cl flux but had no effect on the net Na transport. The 10(-4) M furosemide reduced the SCC 38%. These drugs had no effect when applied to the basal side. Thus the transport of both Na and Cl depends on the Na-K-ATPase in the apical membrane of the dog RPE. A furosemide-sensitive neutral carrier at the apical membrane is suggested for the transport of Cl. Replacement of HCO3 with SO4 in the bathing solution caused an increase in the SCC, indicating the choroid-to-retina movement of HCO3 across the short-circuited dog RPE choroid.

Animals↗
PubMed1986

Effects of forskolin, prostaglandin F2 alpha, and Ba2+ on the short-circuit current of the isolated rabbit iris-ciliary body.

To gain information on the role of cyclic AMP (cAMP), ion transport and cell membrane permeability on aqueous humor formation, agents with well-known effects on transport properties in other epithelia were tested on the isolated rabbit iris-ciliary body. Forskolin stimulated the short-circuit current (SCC) by 37.5% when added to the aqueous-side solution. Forskolin was ineffective when added to the blood-side solution or when HCO3- was absent from the bathing solutions. The effect of forskolin confirms the presence of adenylate cyclase in the ciliary epithelium and the involvement of cAMP in ion transport. In HCO3- -rich media, 5 X 10(-5) M prostaglandin F2 alpha (PGF2 alpha), produced a prompt 25% increase in the SCC when added to the aqueous-side, and a small stimulatory SCC response when added to the blood-side. No change in SCC occurred when PGF2 alpha was added to either side of a HCO3- -free bathing solution. It is implied that cAMP acts on a HCO3- dependent transport system. These results are consistent with the previously observed stimulation of the SCC by 8Br-cAMP. BaCl2, 2.5 mM, on the aqueous-side increased the SCC by 240.5%, but reduced the SCC by 26% when added to the blood-side solution. The Ba2+ effects indicate the presence of high conductance K+ channels in the basolateral membranes of both the pigmented and non-pigmented cell layers.

Animals↗
PubMed1986

Animal model of closed angle glaucoma in albino mutant quails.

The intraocular pressure of imperfect albino mutant quails with a sex-linked recessive gene was measured by using a cannulating method, and morphological changes of the iridocorneal angle were observed with a gonioprism. Albino mutant quails were characterized by an elevated intraocular pressure and lens enlargement at 6 mo after hatching. Initially the iridocorneal angle opened and eventually closed. The usefulness of the closed angle glaucoma as an animal model system for human diseases was discussed.

Animals↗