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Biomedical subjects

A Mizukami

Publications and source records attributed to A Mizukami.

At least 19 recordsLinked to original sources
PubMed2005

Clinical course of fetal congenital atrioventricular block in the Japanese population: a multicentre experience.

OBJECTIVES: To elucidate the prenatal and postnatal course of fetal congenital atrioventricular block (CAVB) during the past decade in the Japanese population. DESIGN: Retrospective multicentre study. All fetuses with CAVB in 10 Japanese institutions in the period from January 1990 to August 2001 were included. PATIENTS: Of the 48 fetuses with CAVB, 17 had a congenital heart defect (CHD) (14 with left atrial isomerism) and 31 had a structurally normal heart (22 with positive maternal autoantibodies). Gestational age at diagnosis was 15 to 38 (median 26) weeks. RESULTS: Of the 17 fetuses with a CHD, three were aborted, one died before birth, and eight died after birth (three in the neonatal period and five after the neonatal period). Of the 31 fetuses without a CHD, two died before birth and two died after birth. CHD (p = 0.005) and the presence of fetal hydrops (p = 0.05) were significant risk factors for death. However, fetal ventricular and atrial heart rates, gestational age at delivery, and birth weight were not related to death. Transplacental medication of sympathomimetics increased the fetal heart rate in five of eight fetuses treated. Dexamethasone did not improve the degree of heart block in any of the six fetuses treated. Postnatally, pacemakers were implanted in 30 of 40 babies. Four fetuses with maternal autoantibodies had decreased cardiac function. CONCLUSIONS: CHD and fetal hydrops are risk factors for prenatal and postnatal death. The fetal ventricular rate of 55 beats/min did not appear to be a threshold value by which to predict fetal hydrops. Patients with CAVB should be subjected to close long term follow up to check for the need for pacemaker implantation or for late onset cardiac dysfunction.

Anti-Arrhythmia Agents↗
PubMed2002

Evaluation of aviguard, a commercial competitive exclusion product for efficacy and after-effect on the antibody response of chicks to Salmonella.

The competitive exclusion (CE) action of Aviguard (AG) and its effects on the antibody response of chicks were evaluated in this study. We observed that AG protected the chicks from overwhelming colonization. Fourteen days after infection, fewer AG-pretreated than nonpretreated chicks shed salmonellae from their coloaca in both infected groups, although much less from SE-infected chicks. Antibody titers of sera produced to Salmonella typhimurium (ST) and SE in pretreated and non-pretreated chicks were not significantly different. Immunoblotting showed that these antibodies reacted with SDS-PAGE-separated 71.4, 67.7, 44.0, and 30.3 kDa proteins detectable in the test strains. Few weak bands of doubtful significance were observed in the cross-reaction between the sera of ST- and SE-infected chicks with ST and SE antigens, respectively. Our study showed that AG protected chicks from overwhelming colonization by salmonellae, and neither altered the antigenic proteins of infecting salmonellae nor their recognition by specific antibodies produced in response to the infection.

Animals↗
PubMed1999

31P NMR studies of phosphate metabolism in the ovulatory process induced by gonadotropins in perfused rabbit ovary.

The concentrations of phosphate metabolites were measured in perfused rabbit ovaries before, during and after ischemia, and during the ovulatory process induced by the administration of pregnant mare serum gonadotropin (PMSG) and human chorionic gonadotropin (HCG) using 31P NMR spectroscopy. A decrease in adenosine triphosphate (ATP) and an increase in inorganic phosphate (Pi) during ischemia were observed. After reperfusion of the ovary, both ATP and Pi levels returned to their initial control levels. These results are in agreement with the results observed in other organ tissues. On the other hand, ATP levels rapidly decreased dose dependently with infusion of HCG during 10 h of perfusion. A decrease in ovarian ATP concentration after infusion of HCG was also confirmed by enzymatic analysis of the extracts from ovarian tissues. On the other hand, significant changes in Pi levels were not observed throughout the perfusion period. Furthermore, significant changes in phosphomonoester (PME) levels, adenosine diphosphate (ADP) levels and intracellular pH were not observed before and during the infusion of HCG. The concentration of cyclic adenosine 3',5'-monophosphate (cAMP) in the perfusate after the perfusion was also measured during the ovulatory period. Within 30 min cAMP significantly increased dose dependently and reached peak levels within 60 min. The concentration of cAMP then gradually decreased. Ovulatory efficacy during the infusion of HCG was also observed. These results suggest that the decreased ATP in the successive processes leading to ovulation probably reflects protein phosphorylation through the activation of the cAMP-dependent protein kinases prior to induction of various chemical reactions related to the initiation of ovulation.

Adenosine Triphosphate↗
PubMed1998

[One-stage repair of interrupted aortic arch with selective cerebral perfusion].

To minimize the neurological compromise after the circulatory arrest, the selective cerebral perfusion could be beneficial. We underwent one-stage repair of the interrupted aortic arch (IAA) with various intracardiac anomalies for the six patients, age ranging from 12 days to 4 months, by using the selective cerebral perfusion. Cardiopulmonary bypass was established by using two-way arterial cannulation supported by the two respective pump systems, one of which utilized the EPTFE graft anastmosed to either the bracheocephalic artery or the right subclavian artery and second of which enrouted through the arterial ductus to the descending aorta. The cerebral perfusion during the circulatory arrest for the aortic arch repair was maintained by the selective perfusion via EPTFE graft with 10 ml/kg/min blood flow. After the completion of the arch repair, the total system perfusion was restarted through the graft and the repair of the intracardiac anomalies was followed. Of six, no operative death or neurological complications related to the operation were found. The clinical neurological evaluation after operation also demonstrated the normal for the age. In conclusion, the selective cerebral perfusion by using the EPTFE graft during the circulatory arrest might decrease the risk of brain damage.

Aorta, Thoracic↗
PubMed1998

[Cases of multiple ventricular septal defects].

We had 4 cases with multiple ventricular septal defects (VSDs) in complexed congenital heart disease. One of four had two separate VSDs detected by two dimensional echocardiography before operation. Second of four had additional infundibular muscular VSD which was detected by echocardiography in the intensive care unit (ICU) after patch closure of a perimembranous VSD. The third case had two additional VSDs of inlet muscular and subaortic septum detected by transesophageal and direct echocardiography during reoperation, beside a subpulmonary VSD which was originally diagnosed before Jatene operation for double outlet right ventricle. The fourth case had multiple trabecular muscular VSDs diagnosed by postoperative angiography soon after Rastelli operation. Since these additional multiple VSDs compromise the postoperative hemodynamics if those are unrecognized, it is indispensable to detect all VSDs before operation, using transthoracic and transesophageal echocardiography.

Echocardiography↗
PubMed1997

FMRF amide-like-immunoreactive primary sensory neurons in the olfactory system of the terrestrial mollusc, Limax marginatus.

The distribution of FMRF amide-like immunoreactivity was investigated in the olfactory organs in the tentacle tip of the terrestrial slug, Limax marginatus. Approximately 0.7% of the neurons in the lobules of the tentacle ganglia demonstrated FMRF amide-like immunoreactivity. Most of the FMRF amide-like-immunoreactive somata lay at superficial positions within the lobules, and dendritic processes extended to the outer surface of the sensory epithelium, whereas the axons traveled toward the cerebral ganglion through the ventral part of the tentacle nerve. From their morphological features, FMRF amide-like-immunoreactive cells were considered to be primary sensory neurons.

Animals↗
PubMed1995

Direct reconstitution of bacteriorhodopsin into planar phospholipid bilayers--detergent effect.

This paper describes how the structure and concentration level of a detergent used for substitution after bacteriorhodopsin (bR) solubilization affect the reconstitution of the bR into phospholipid planar bilayers. A direct insertion method was used for the bR reconstitution into the bilayers. Two detergents representing the two major types were used: sodium deoxycholate with a cholane-ring structure, and octylglucoside with a linear (or chain) structure. We then characterized the reconstitution for the two detergents by considering the detergent separation profiles and the photocurrent variations upon addition of lanthanum chloride and the protonophore FCCP (carbonylcyanide-p-trifluoromethoxyphenylhydrazone). We found that for successful transmembrane reconstitution of bR the detergent with the cholane-ring structure was preferable to that with the linear structure when the detergent concentration was above its critical micellar concentration. This preference was explained by the ease with which the detergent with the cholane-ring structure was removed from protein compared to that with the linear structure. Finally, we proposed a scheme for the reconstitution of the protein.

Journal Article↗
PubMed1995

Oscillatory phenomena in model membrane: electrical oscillation in lipid-impregnated membrane filter induced by alamethicin and controlled by bacteriorhodopsin.

A lipid-impregnated membrane filter was able to show reproducibly of an electrical oscillation under constant current stimulation when alamethicin and protamine were present in the chamber whose salt concentration was higher than the other and the membrane was left for about 12 h. In addition, bacteriorhodopsin, which is a light-activated proton pump, was found to control the oscillation. The oscillatory phenomenon was considered to be driven by the alternating change in the ion-selectivity of the membrane between cation and anion. Impedance measurement indicated the existence of lipid rearrangement which might prepare an environment for both alamethicin and protamine to cause the oscillation.

Alamethicin↗
PubMed1994

Cooling-induced retrograde amnesia reflexes Pavlovian conditioning associations in Limax flavus.

The relationships between cooling-induced retrograde amnesia and associations in Pavlovian conditioning in the terrestrial mollusk Limax flavus were studied. In the first experiment, the slugs were conditioned to avoid carrot odor and the experimental conditions required for amnesia induction were studied. Memory reactivation before cooling was found to be necessary for amnesia induction and the induced amnesia was selective for the reactivated memory. In the subsequent experiments, slugs were conditioned to avoid both carrot and cucumber odors using one of three Pavlovian conditioning paradigms, namely two-independent first-order conditioning, phase-2-sequential second-order conditioning and phase-2-simultaneous second-order conditioning, after which amnesia was induced by cooling immediately after presentation of one of the conditioning odors. The amnesia pattern induced differed depending upon the conditioning procedure used, which indicated that amnesia induction was related closely to stimulus associations in slugs. The possible role of cooling-induced retrograde amnesia as a tool for studying memory associations is also discussed.

Amnesia, Retrograde↗
PubMed1994

Age-dependent changes related to reproductive development in the odor preference of blowflies, Phormia regina, and fleshflies, Boetteherisca peregrina.

We investigated the preference for the odor of decaying meat in a T-maze using female and male blowflies, Phormia regina, with one of two nutritional histories (protein-containing or protein-free diet), and compared them with fleshflies, Boetteherisca peregrina. The preference showed age-dependent changes, which differed according to sex and nutritional history. Females in both nutrition groups showed a high preference for the odor. The preference of protein-fed females showed cyclic variations corresponding to the ovarian cycle, while the protein-deficient group, which never oviposited having immature eggs, did not exhibit cyclic changes and their preference remained high. These results suggest that the preference for the odor may be associated with the ovarian cycle. In males, both nutrition groups showed significant changes with age. The preference of protein-deficient males changed similarly to that of females, whereas protein-fed males were not attracted by the odor. This also suggests that the preference for the odor may be related to reproductive development. With B. peregrina, which has different reproductive natures from P. regina, the age-dependent changes in the preference did not differ so markedly with sex and nutritional history as with P. regina.

Age Factors↗
PubMed1993

[The 31P-NMR spectroscopic study of phosphate metabolism of perfused rabbit ovary in ovulation].

The phosphate metabolites in perfused rabbit ovary were measured during ovulation by 31P-NMR spectroscopy after the administration of PMSG and HCG. The c-AMP levels in perfusate from opposite ovarian veins were also measured by RIA. The results obtained were as follows: (1) The ovulatory ATP level significantly decreased compared with the preovulatory ATP level. After ovulation, the ATP level gradually recovered to the control level. On the other hand, both neither the Pi nor the PME level changed significantly from the preovulatory until the preluteal phase and recovered to the control level after the midluteal phase. (2) ATP levels rapidly decreased dose-dependently after the administration of HCG during ovulation. The ATP level in particular decreased significantly to 62.4% and 51.4% of the control level at 2 and 10 hours, respectively during the infusion of 10 IU/min of HCG. However, no significant change in either the Pi or the PME level was observed until the end of perfusion. (3) The concentration of c-AMP in the perfusate significantly increased dose-dependently after the administration of HCG. The concentration of c-AMP reached its peak level at 30 minutes after 10 IU/min HCG infusion from control level, and gradually decreased in the 10 hours after HCG infusion. These results suggest that the decrease in ATP during ovulation may reflect the increase in ATP consumption in the c-AMP dependent metabolic pathway in the ovary.

Adenosine Triphosphate↗
PubMed1992

Antigenic determinants of senescent antigen of human erythrocytes are located in sialylated carbohydrate chains of Band 3 glycoprotein.

Naturally occurring IgG autoantibody against Band 3 glycoprotein of human erythrocyte membrane (anti-Band 3) recognizes the erythrocytes modified with oxidizing or SH-blocking agents as well as senescent erythrocytes. Location of the antigenic determinants of Band 3 this autoantibody recognizes was investigated by competitive inhibition studies of the antibody binding to the modified cells. Autologous IgG binds to the modified erythrocytes, and purified Band 3 totally inhibits the binding. This inhibitory activity of Band 3 was not affected by digestion of Band 3 with various proteases. Treatment of Band 3 with endo-beta-galactosidase that destroys the poly-N-acetyllactosaminyl sugar chain of Band 3 or with neuraminidase resulted in loss of the inhibitory activity. Oligosaccharides released from Band 3 by hydrazinolysis effectively inhibited the binding of autologous IgG and 125I-labeled purified anti-Band 3 to the modified cells, whereas the oligosaccharides depleted of acidic components did not. Endo-beta-galactosidase and neuraminidase destroyed the activity of the oligosaccharides, but alpha-L-fucosidase did not. Furthermore, human lactoferrin that contains sialylated two N-acetyllactosaminyl units also exhibited potent inhibitory activity, and the activity was destroyed by endo-beta-galactosidase and neuraminidase. These results indicate that the antigenic determinants of Band 3 are located in sialylated poly-N-acetyllactosaminyl sugar chains. Based on this finding, mechanism of appearance of the antigen on senescent erythrocytes recognized by anti-Band 3 (senescent antigen) was discussed.

Anion Exchange Protein 1, Erythrocyte↗
PubMed1992

Generation of senescent antigen on erythrocytes by partial blocking of SH groups of the membrane proteins.

Human erythrocytes treated with diamide (0.2 mM) or N-ethylmaleimide (0.1 mM) at 37 degrees C for 1 h were susceptible to binding of anti-band 3 immunoglobulin G autoantibody and hemoglobin. A definite degree of cell modification appeared to be required for the effective bindings since the cells treated with the reagents above these concentrations were less susceptible. The enhanced binding activities of the cells treated with diamide were abolished on treatment with dithiothreitol. Partial blocking of SH groups of the membrane proteins but not disulfide-mediated protein cross-linking may be essential for the formation of band 3 senescent antigen, which may not be a neo-antigen formed by chemical modification of band 3 but an antigen formed by topological alterations of the molecules in the membrane.

Anion Exchange Protein 1, Erythrocyte↗
PubMed1992

Behavioral analysis of internal memory states using cooling-induced retrograde amnesia in Limax flavus.

Temporal evolution of internal memory states in a terrestrial mollusk, Limax flavus, was studied using cooling-induced retrograde amnesia. The slug was conditioned to avoid carrot odor by temporally correlated presentation of carrot juice and a bitter-taste stimulus of quinidine sulfate. We could induce retrograde amnesia by cooling of the conditioned slug immediately after the training trial. Thus, we studied the memory states in the slug using the retrograde amnesia according to strategies used in the studies of memory states in mammals or insects. In the early process of memory acquisition, at least two distinctive memory states were observed, short-term memory and long-term memory (LTM). For LTM, two states were also observed. One was a reactivated state of LTM, which was sensitive to the cooling used to induce the amnesia. The other was a so-called resting state of LTM, which was insensitive to cooling. A few days after memory acquisition, further evolution was observed in that the amnesia could not be induced even if the memory trace was reactivated. The results obtained in Limax flavus was comparable with those obtained in a variety of animals.

Amnesia↗
PubMed1990

Binding of anti-band 3 autoantibody to oxidatively damaged erythrocytes. Formation of senescent antigen on erythrocyte surface by an oxidative mechanism.

Incubation of human erythrocytes oxidized by iron catalysts, ADP/Fe3+ or xanthine/xanthine oxidase/Fe3+, with autologous IgG resulted in IgG binding as detected by enzyme immunoassay using protein A-beta-galactosidase conjugate. The binding of autologous IgG to ADP/Fe3(+)-treated erythrocytes maximized when the cells were treated with 1.8:0.1 mM ADP/Fe3+, and declined when treated above this concentration, suggesting that autologous IgG binds to moderately but not to excessively oxidized erythrocytes. The antibody involved in the binding was anti-Band 3, the autoantibody known to bind to aged erythrocytes, because isolated anti-Band 3 bound to the oxidized cells, but anti-Band 3-depleted autologous IgG did not. In addition, purified Band 3 inhibited the autologous IgG binding. Anti-alpha-galactosyl IgG, another natural antibody which has been reported to bind to aged erythrocytes, did not bind to the oxidized cells. Oxidation of membrane lipids, SH-groups of membrane proteins, and Hb of these cells was slight, but the cells contained an increased amount of membrane-bound native Hb, indicating that the oxidized cell membrane has an altered property. alpha-Tocopherol prevented the lipid oxidation and the subsequent IgG binding. Reduction of the oxidized erythrocytes with dithiothreitol resulted in a loss of the IgG binding. These results suggest that anti-Band 3 binding sites (Band 3 senescent antigen) are formed on moderately oxidized erythrocytes as a result of oxidation of membrane protein SH-groups which can be mediated by the membrane lipid oxidation and that formation of the anti-Band 3 binding sites on the oxidized cells is an essentially reversible membrane event which is linked to oxidation and restoration of the protein SH-groups.

Adenosine Diphosphate↗
PubMed1990

[Effects of lactulose on blood ammonia levels in beagles with end-to-side portacaval shunt].

The effects of lactulose on blood ammonia and fecal pH in beagles with an end-to-side portacaval shunt were investigated. Concentrations of blood ammonia before and two weeks after the operation were 4.65 +/- 0.34 micrograms/ml (N = 12) and 8.66 +/- 0.60 micrograms/ml (N = 6), respectively (P less than 0.01), while there was no significant difference in fecal pH values before and after the operation. The blood ammonia concentrations in the control and lactulose-treated (2.1 g/kg, p.o.) groups after administration of meat were 12.65 +/- 1.64 micrograms/ml (N = 8) and 8.45 +/- 0.90 micrograms/ml (N = 8), respectively (P less than 0.05). The fecal pH values in the control and lactulose-treated (2.1 g/kg, p.o.) beagles were 6.24 +/- 0.09 (N = 8) and 5.58 +/- 0.08 (N = 8), respectively (P less than 0.01). The lowering effect of lactulose on the blood ammonia levels could not be ascribed to its laxative action alone, because the oral administration of lactulose at doses less than 2.1 g/kg induced no fluid evacuation. The present studies in the beagle suggest that the action of lactulose produce a lowering of fecal pH, causing an increase in the concentration of less absorbable ammonium ions and a decrease in the production of toxic nitrogenous compounds such as ammonia, resulting in a reduction in blood ammonia levels.

Administration, Oral↗