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Biomedical subjects

Y Kawamoto

Publications and source records attributed to Y Kawamoto.

At least 19 recordsLinked to original sources

Plasmodium berghei: sporozoites are sensitive to human serum but not susceptible host serum.

Human complement was activated by rodent malaria, Plasmodium berghei, sporozoites through the alternative pathway, as revealed by C3 deposition on sporozoites using the fluorescent antibody technique. Sporozoites exposed to fresh human serum decreased in infectivity to HepG2 cells, but those exposed to heated or C3-deficient human serum showed normal infectivity to HepG2 cells. In contrast, C3 deposition was not observed on the sporozoites treated with mouse or rat serum even in the presence of specific polyclonal anti-sporozoite antibody. However, following treatment with trypsin (250 micrograms/ml), 81% of salivary gland sporozoites and 49% of oocyst sporozoites became reactive with mouse serum, and reactive sporozoites deposited mouse C3 on their surface in the presence of 30 mM EGTA and 1 mM Mg2+ without antibody. Concomitantly some sporozoites lost reactivity to anti-circumsporozoite protein monoclonal antibody. These results suggest that P. berghei sporozoites possibly express surface molecules that regulate the complement activation pathway of susceptible hosts but not of nonhosts, and that the putative structures consist of protease-sensitive molecule(s) which are closely associated with the circumsporozoite protein.

Animals

Intracranial metastasis from a spinal cord primitive neuroectodermal tumor: case report.

A patient with intracranial seeding from a spinal cord primitive neuroectodermal tumor with ependymal differentiation is presented. The first and second stages of intracranial dissemination were well controlled by a combination of irradiation and chemotherapy. The authors review previously published cases and discuss the possible mechanism of seeding from the spinal cord to the intracranial region.

Adolescent

Reconstituted collagen is not capable of activating factor XII but causes intrinsic coagulation by activating platelets.

Using a rheological technique to measure the coagulation of plasma in collagen-coated tubes, we studied the intrinsic coagulant activities of different types (I, III, IV and V) and structures of reconstituted collagen. Recalcified, platelet-free plasma (PFP) in contact with the collagen surface did not clot, irrespective of the type and structure of collagen. Coagulation of platelet-rich plasma (PRP) did occur, although the time of onset of coagulation was highly dependent on the type and structure of the collagen used. Coagulation of PRP occurred rapidly on a collagen surface consisting of highly ordered fibrils (banded structure) to which large numbers of aggregated platelets adhered with shape change. In contrast, initiation of coagulation was delayed in PRP after incubation with 5 mM dibutyrylcyclic AMP (DB-cAMP) for 50 min. Coagulation of PRP was completely suppressed after 30 min incubation with colchicine (5.0 mg/ml). This suggested that disruption of platelet microtubules completely suppressed the stimulation of platelets associated with the initiation of intrinsic coagulation on the collagen surface. We conclude that reconstituted collagen is not capable of activating factor XII. Initiation of coagulation of recalcified PRP in contact with the reconstituted collagen surface is caused by the activation of platelets.

Adult

[Choroid plexus papilloma of the third ventricle in infancy: a case report].

The incidence of choroid plexus papilloma is about 0.5% of all intracranial tumors, but they are only infrequently found in the third ventricle. This is a case report of choroid plexus papilloma of the third ventricle in an infant. A make child in his 7th month of age was admitted because of large head circumference, on the 28th February, 1989. CT scan demonstrated hydrocephalus caused by a tumor in the third ventricle. Total removal of the tumor was performed on the 8th of March. Histologically the tumor was found to be choroid plexus papilloma. The patient suffered from postoperative subdural effusion and convulsions, so we performed ventriculoperitoneal shunt on the 14th April, and convulsions were controlled by zonisamid.

Age Factors

Orosomucoid typing of apes (family Pongidae) by isoelectric focusing: among primates do only humans have two functional orosomucoid loci?

It has been demonstrated that human orosomucoid (ORM) is controlled by more than one functional loci, while Macaca ORM is controlled by one locus. To examine the time when the ORM gene was duplicated in the evolution of primates, plasma samples from 118 apes (family Pongidae) belonging to 4 genera and 12 species were investigated for ORM polymorphism using isoelectric focusing followed by immunoprinting. The band patterns of ORM in the subfamily Ponginae showed quantitatively different products as in humans. A pedigree study of common chimpanzees supported the two-locus model for ORM. Gibbons (subfamily Hylobatinae) displayed highly variable band patterns, but the number of loci was not determined unequivocally. Thus, this study shows that duplication of the ORM gene in primates occurred either before or after the divergence of Hylobatinae and Ponginae, consistent with a previous prediction from the molecular evolutionary rate of ORM.

Alleles

Purification and immunochemical characterization of a recombinant outer membrane protein from Bacteroides gingivalis.

1. Bacteroides gingivalis is thought to be one of the most virulent microorganisms in relation to adult periodontitis. A gene clone, MD125, is an Escherichia coli host which produces an outer membrane protein of B. gingivalis. 2. The recombinant outer membrane protein (rOMP) was purified to homogeneity from cell sonicate of MD125 by four chromatographic steps. The molecular weight of the purified rOMP was estimated to be approximately 40 kDa. 3. Immunodiffusion analysis showed that antiserum against whole cells of B. gingivalis reacted not only with B. gingivalis cells but also with other Bacteroides cells. Antiserum against the purified recombinant protein reacted with cells of B. gingivalis, whereas this antiserum did not react with all of the other Bacteroides species tested. 4. These data suggest that the rOMP may be a B. gingivalis-specific antigen and that the purified rOMP will be useful material for serodiagnosis and for the development of a vaccine against B. gingivalis infection.

Bacterial Outer Membrane Proteins

[Mechanism of protective effects of ouren-gedoku-to and san'ou-syashin-to on the gastric mucosa].

Ouren-Gedoku-To (OGT) and San'ou-Syashin-To (SST), traditional Chinese prescriptions, have been used to treat peptic ulcer. In order to elucidate the mechanism of the protective effects of OGT and SST on the gastric mucosa, we studied their effects on gastric mucosal lesions, ion permeability and prostaglandin synthesis using ulcer experimentally induced in rats by saturation with acidic test solution after taurocholate treatment. Both OGT and SST inhibited taurocholate-induced gastric mucosal lesions in a dose-related manner. These prescriptions dose-dependently inhibited not only the increase of hydrogen and sodium ion net fluxes but also possible hydrogen ion back diffusion into the gastric mucosa during saturation with acidic test solution. SST induced a significant increase in gastric mucosal prostaglandins synthesized from 14C labeled arachidonate. These results suggest that both OGT and SST by strengthening the gastric mucosal barrier demonstrate their protective effects on the gastric mucosa and that this effect of SST is attributable to the increased ability of the gastric mucosa to synthesize prostaglandin.

Animals

Selection of mouse strains showing high and low incidences of alloxan-induced diabetes.

To produce an experimental model of diabetes in animals, ICR mice were inbred until the 20th generation by two-way selection toward the high- and low-incidences of alloxan-induced diabetes. Changes in successive generations in the incidence of such diabetes, in blood glucose levels, growth patterns and reproductive performance were studied. The incidence of alloxan-induced diabetes was 41.1% in the basal population; in the high-incidence strain, it was 98.7% in F13, ranging between 90 and 99% in later generations; and in the low-incidence strain, it reached 0% in F7, remaining near that level in later generations. The heritability of the incidence of alloxan-induced diabetes determined at the beginning of selection was 50-60%. The blood glucose level was 251 +/- 19 mg/dl in the basal population; in the high-incidence strain, it was 423 +/- 11 mg/dl in F13, ranging thereafter between 340 and 455 mg/dl; and in the low-incidence strain, it was 128 +/- 4 mg/dl in F7, then varying from 120 to 140 mg/dl in following generations. The heritability of the blood glucose level determined at the beginning of selection was 40-60%. No marked decrease in growth or reproductive performance accompanied successive selections. Successive generations of the high-incidence mice, however, tended to become heavier than the low-incidence animals. The high- and low-incidence strains, established in the 20th generation, were named the ALS (alloxan-induced diabetes-susceptible) and ALR (alloxan-induced diabetes-resistant) strains, respectively.

Animals

Selective breeding of two lines of guinea pigs differing in bronchial sensitivity to acetylcholine and histamine exposure.

We developed two lines of guinea pigs, one as model animals for bronchial asthma with bronchial hypersensitivity and the other with hyposensitivity as a control. In the last four years, the bronchial hypersensitive line (BHS) and hyposensitive line (BHR), both derived from Hartley strain guinea pigs, have been selected by using bronchial reactivity to acetylcholine and to histamine as parameters. Both lines have reached the F6 generation. The following results were obtained with the two lines: 1) Sib and cous in matings, and mating of selected consanguineous individuals were adopted in breeding BHS and BHR. The breeding started with six families, each, but in the F6 generation the number of families decreased to two in each line. 2) Appearance rates of hyper- or hyposensitivity to acetylcholine and histamine increased with successive generations in both lines, which had been completely separated by the F6 generation. 3) Coefficients of inbreeding in BHS and BHR in the F6 generation ranged from 42% to 45% in the former and 42% in the latter. 4) Heritabilities (h2) of BHS and BHR for the appearance rates of sensitivity to acetylcholine were presumed to be 0.54 in the former and 0.69 in the latter. 5) No difference in the body weight of 0, 20, and 40 day-old BHS was observed in any generation. On the other hand, the body weight of 20 and 40 day-old BHR tended to decrease with successive generations. 6) Mean litter sizes of BHS and BHR in each of the generations ranged from 2.24 to 3.47 animals in the former and from 2.63 to 3.38 animals in the latter.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetylcholine

[Diabetic peculiarity of the ALS-Ay and ALR-Ay strains].

ALS and ALR mice were developed as mouse models of alloxan-induced diabetes. These strains do not show spontaneous onset of diabetes. When an obesity gene (Ay) was introduced to these two strains, severe diabetic conditions occurred spontaneously in the produced ALS-Ay and ALR-Ay strains. These strains were examined body weight gain, food consumption, water consumption, urinary sugar content, ketone body level and blood sugar level, and subjected to glucose tolerance test. As a result, in comparison with ALS mice, male ALS-Ay mice showed no obesity and very low tolerance to the glucose tolerance test performed 24 weeks after birth. The level of insulin secretion was 5.0 microU/ml or less, showing hardly any secretory reaction. On the other hand, female ALS-Ay mice were obese and showed no marked decrease in glucose tolerance. The level of insulin secretion was high, and the secretory reaction was strong. In ALR-Ay strain, both male and female mice were obese and showed diabetic conditions similar to those of ALS-Ay mice, though the severity tended to be lower. The characteristic features of diabetic conditions in these mice suggest that these strains, particularly ALS-Ay, may serve as useful new-type models of diabetes.

Alloxan

Characteristics of two lines of guinea pigs (BHS and BHR) differing in bronchial sensitivity to acetylcholine and histamine exposure.

In a previous study, we reported that as model animals to be used in the study of bronchial asthma in humans, two lines of guinea pigs were developed by ourselves: bronchial hypersensitive line (BHS) and bronchial hyposensitive line (BHR) as a control. Studies on biological characteristics in guinea pigs of two lines were undertaken, and the following results were obtained. 1) Airway resistance of guinea pigs of the two lines to intravenously administered acetylcholine, histamine and leukotriene D4 was found to be different between BHS and BHR. Airway resistance of BHS to the chemicals was increased compared with those of BHR. 2) The number of muscarinic acetylcholine receptors in lung membrane preparation and its affinity increased significantly in BHS compared with those of BHR. In beta-adrenergic and histamine H1 receptors, there was observed no difference between BHS and BHR. 3) No difference in IgE antibody production to ovalbumin was observed between BHS and BHR. 4) When total leukocytes and differential leukocyte count (percentage, %) in peripheral blood of BHS and BHR were examined, relative percentage of lymphocytes and eosinophils was significantly higher in BHS than in BHR, while percentage of neutrophils was significantly lower in the former than in the latter.

Acetylcholine

Rheological measurement of blood coagulation in vascular vessel model tube consisting of endothelial cells monolayer.

An in vitro experimental system was developed to study the interaction between endothelial cells and blood as an early event in coagulation. A designed vascular vessel model tube is composed of a monolayer of bovine aorta endothelial cells (BAECs) cultured on an inner surface of a glass tube by means of a rotatory cultivation method. The change of fluidity during coagulation of blood in the tube was measured by a rheological technique. The rate of coagulation of blood in contact with endothelial cells was affected by cell culture conditions such as cell age, passage number of BAECs and substrate beneath endothelial cells. Fibrinolytic activity of the cells was examined by the rheological method. The present experimental system would be useful in examining the mechanism of blood coagulation based on the interaction between blood and endothelial cells as well as in evaluating endothelial cell functions.

Animals

Genetic polymorphism of the vitamin D-binding protein (DBP) in crab-eating macaques (Macaca fascicularis).

Vitamin D-binding protein (DBP) of crab-eating macaques (Macaca fascicularis) was examined by means of three electrophoretic methods. DBP phenotypes were observed to be one or two bands in each method. All of DBP molecular variants could be detected by the simultaneous typing with these three methods. Family analysis suggested that DBP variants followed the mode of autosomal codominant inheritance. A total of 17 phenotypes governed by at least 11 alleles were observed in the populations of Malaysia, Indonesia, and the Philippines. The genetic variability was high in Malaysian and Indonesian populations but low in the Philippine population.

Alleles

Procoagulant activity of collagen. Effect of difference in type and structure of collagen.

Procoagulant activities of different types and structures of collagen were examined. Collagens used were types I (including its methylated and succinylated forms), II, III, IV and V. Each collagen was coated on an inner surface of a glass tube. The change of fluidity during coagulation of blood in the tube was measured by means of a new rheological technique. For monomeric collagen, the procoagulant activity of the succinylated form (negatively charged) was higher than that of the methylated form (positively charged). The procoagulant activity of type IV (dry) was lower than that of other types of collagen. For fibrillar collagens, the initiation of coagulation for type V (non-banded) was fairly delayed compared to those for types I, II and III (banded). An increase in water content in both monomeric and fibrillar forms promoted procoagulant activity. For most of the collagen forms, the addition of factor XII inhibitor (Polybrene) to blood brought about a remarkable delay of the initiation of coagulation, suggesting that the activation of factor XII on the collagen surface is one of main factors governing procoagulant activity. In addition, our data suggest that large numbers of adherent platelets to the collagen surface promote activation of the intrinsic coagulation system.

Adult

Identification of hemolytic granules isolated from human myocardial cells.

Human myocardial cells from fresh autopsy material contained granules which possessed hemolytic activity against guinea pig and rabbit erythrocytes. The hemolytic granules, which had a density of 1.02 and a diameter of 200-300 nm, were recovered as a microsome fraction from subcellular homogenates of human myocardial cells by differential centrifugation in 300 mM sucrose containing 0.1 mM PMSF and 10 mM EDTA. The membrane lesions caused by the granules were ring-like structures with an internal diameter of about 10-17 nm, analogous to that caused by perforin- and complement-induced lysis. However, the requirement for divalent cation differed from that for perforin-induced lysis, since the microsome-mediated lysis occurred in the presence of EDTA.

Animals

Orosomucoid typing by isoelectric focusing: genetic variation of orosomucoid in Asian macaques (genus Macaca).

Genetic variation of orosomucoid (ORM) in the genus Macaca was investigated. Plasma samples were subjected to isoelectric focusing in a pH range of 4-6.5, followed by immunoprinting with anti-human ORM antibodies. A total of 25 alleles were identified in 231 Asian macaques belonging to 13 species from 23 populations and 22 members belonging to a family of M. fascicularis. Family data presented evidence for a codominant mode of inheritance with multi-alleles at a single autosomal locus. A population study revealed enormous intra- and interspecies variations. The heterozygosity values varied from 0.855 in M. fascicularis (Malaysia) to 0.000 in M. radiata (India), M. silenus (India) and M. arctoides (Malaysia).

Animals

Possible roles of Ca2+ and cGMP as mediators of the exflagellation of Plasmodium berghei and Plasmodium falciparum.

The roles of Ca2+ and cyclic nucleotides as secondary, intracellular messengers for exflagellation of Plasmodium berghei and Plasmodium falciparum were investigated. Treatment with Ca2+ antagonists such as TMB-8 (an inhibitor of intracellular Ca2+ release) or W-7 (a calmodulin inhibitor) strongly inhibited exflagellation induced by alkaline medium at pH 8.0 whereas EGTA (a Ca2+ chelator) or nicardipine and nifedipine (Ca2+ channel inhibitors) had no effect. These results may indicate that mobilization of parasites' internal resources of Ca2+ is a prerequisite for exflagellation. Agents which increase cAMP levels did not induce exflagellation at the non-permissive pH of 7.3, and had no significant inhibitory effect at the permissive pH of 8.0. IBMX (cAMP/cGMP-phosphodiesterase inhibitor), however, enhanced exflagellation at pH 7.3, indicating the possibility that cGMP, but not cAMP, may be involved in the induction of exflagellation. Furthermore, cGMP or agents which increase cGMP levels such as nitroprusside (a potent activator of guanylate cyclase), enhanced exflagellation at pH 7.3, whereas N-methyl-hydroxylamine (guanylate cyclase inhibitor) inhibited the exflagellation at pH 8.0. From these results, it may be concluded that the induction of exflagellation requires both Ca2+ mobilization and an increase in cGMP levels.

Animals