Search PubMed⌕ Search

Biomedical subjects

H Miyata

Publications and source records attributed to H Miyata.

At least 271 records · Page 15Linked to original sources
PubMed1993

Electron microscopic studies on reticular fibers in the pig sheathed artery and splenic cords.

The reticular fibers of the capillary sheath and splenic cord were studied in the pig spleen by transmission electron microscopy to reveal their components and the presence of sialic acid in the amorphous ground substance. Collagen fibrils, elastic fibers, microfibrils, nerve fibers and smooth muscle cells were observed in the reticular fibers of the splenic cord, while only microfibrils were recognized in the reticular fibers of the capillary sheath. The binding of LFA lectin to the splenic cord was stronger than the capillary sheath. These findings may suggest that the reticular fibers of the splenic cord include numerous functional elements and perform an important role during contraction or dilation of the spleen. On the other hand, it seems to be reasonable to term the capillary sheath as "capillary basement membranous reticular tissue", since the reticular fiber of the capillary sheath resembles the basement membrane of the capillary in its components.

Animals↗
PubMed1993

Three-dimensional reconstruction of the pig sheathed artery.

The structure of the sheathed artery and the number of branches of the sheathed capillary were investigated by three-dimensional reconstruction computer graphics in the pig spleen. The capillary branched 1 to 6 times in the capillary sheath in more than 90% of all samples examined. The sheathed artery varied in shape and size in accordance with the number of branches and direction of the capillary. The usual descriptions for the sheathed artery were suggested to be mostly in appropriate at least for that of the pig spleen.

Animals↗
PubMed1993

Serological evidence of pneumonia virus of mouse (PVM) infection in laboratory rats.

PVM specific antibody was determined using 3 serological tests (Parker's original hemagglutination-inhibition [HI] test, modified HI test, and indirect fluorescent antibody [IFA] test). IFA test was found to be the most sensitive method, so that IFA test was considered to be the method of choice for a small scale microbiological monitoring in animal facilities. A total of 1,280 sera including rats, mice, hamsters and rabbits were tested for PVM antibody. The prevalence of PVM antibody was 17.2% (116/674) in conventional rats and 30.0% (160/200) in SPF rats obtained from commercial breeders and research facilities. Furthermore, two samples of 144 conventional rabbits (1.4%) were showed specific antibody positive to the virus. However, hamsters and mice showed no evidence of PVM infection. These results suggest that PVM infection is prevalent, especially in laboratory rats in Japan.

Animals↗
PubMed1993

[A study of antigenic characterization of Tamm-Horsfall glycoprotein using monoclonal antibodies].

Monoclonal antibodies (Mo-Abs) were prepared by fusing mouse myeloma cells (PAI) with spleen cells of mice immunized with Tamm-Horsfall glycoprotein (THGP). Six Mo-Abs screened for the presence of anti-THGP antibodies by enzyme linked immunosorbent assay and by immunoblotting assay have been produced. The specificity studies clearly indicated that the Mo-Ab individualized four distinct epitopes. The immunofluorescent reaction by the Mo-Abs have been analyzed in the human kidney section with normal or a minimal change. The No. 1, 2, 3 and 5 of Mo-Abs reacted with the cytoplasm of distal convoluted renal tubules, while the No. 4 and 6 of Mo-Abs reacted with a substance in the capsular space as well as with the cytoplasm of distal convoluted tubules. The sites of synthesis of this substance, detected in the capsular space by No. 4 and 6 of Mo-Abs and held the immunological cross-reactivity with tubular THGP, is presently uncertain. The specificity of the Mo-Ab may be of considerable value for further studies.

Animals↗
PubMed1993

The discriminative effects of nicotine and their central sites in rats.

The mediations in the central sites of the discriminative effects of nicotine were studied. Rats were trained to discriminate between the effects of nicotine at 0.5 mg/kg, sc and saline under a fixed ratio 10 schedule, for food reinforcement in a 2-lever operant chamber situation. After the establishment of discrimination behavior, guide cannulae were implanted bilaterally into the lateral ventricle (n = 10), the nucleus accumbens (n = 11), the ventral tegmental area (n = 7), and the dorsal hippocampus (n = 9). In substitution tests, nicotine at 100 and 120 micrograms per rat administered into the lateral ventricle and this drug at 100 micrograms per rat administered into the nucleus accumbens substituted for subcutaneous nicotine. On the other hand, neither nicotine at 10-80 micrograms per rat administered into the ventral tegmental area, nor this drug at 5-20 micrograms per rat administered into the dorsal hippocampus substituted for the subcutaneous nicotine. In antagonism tests, mecamylamine was administered into each brain area in combination with nicotine at 0.5 mg/kg, sc. Mecamylamine at 180 micrograms per rat administered into the nucleus accumbens blocked the discriminative effects of the subcutaneous nicotine while mecamylamine, administered into the ventral tegmental area and the dorsal hippocampus, did not. These results may indicate that the discriminative effects of subcutaneous nicotine are at least partially mediated in the nucleus accumbens.

Animals↗
PubMed1993

[Idiopathic thrombocytopenic purpura in childhood: retrospective analysis of the clinical prognosis].

To evaluate the relationship between initial therapy and clinical prognosis, retrospective analyses were performed in 73 children with idiopathic thrombocytopenic purpura treated in our hospital during the past 12 years. The patients were classified into three groups as follows: group A, 34 patients recovered from thrombocytopenia within six weeks after onset; group B, 9 patients recovered in a period of six weeks to six months; group C, 30 patients remained thrombocytopenia beyond six months. The majority of the patients in group A (82%) and group B (56%) provided a history of some infection within the preceding three weeks. The patients in group A and group B had epistaxis or purpura of mucous membranes more frequently than the patients in group C. Although, in group A and group B, steroid therapy and intravenous high-dose immunoglobulin (IVIG) therapy has been shown to rapidly increase platelet counts, many patients had become thrombocytopenia again from ten days after starting treatment. Therefore, there was no evidence that steroid therapy and IVIG therapy could reduce a total period of the thrombocytopenia compared with no treatment. The evidence suggested that those therapies, steroid therapy and IVIG therapy, might have influenced the essential natural history of the condition. The mean platelet associated IgG values in group C was significantly greater than in group A and group B with the platelet counts exceeds 100,000/microliters.

Adolescent↗
PubMed1993

[Severely handicapped children and its relationship with perinatal medical care].

We studied the etiology for sixty-eight severely handicapped children aged between 3 and 6 years, who were born in the Himeji city and the environs (9,900 live births/year). The prevalence was around 1.7/1,000 live births. The factors of their handicaps were as follows: congenital 25%; perinatal 40%; neonatal period 21%; and unknown onset 15%. Thirty-six patients out of 54 (67%) were admitted to neonatal intensive care unit (NICU) and visited the Center for neurological follow up immediately after their discharge. The high frequency of patients from NICU, compared with previous reports, might be due to a cooperative network between NICUs and the Center with medical support for handicapped children in this area.

Birth Weight↗
PubMed1993

[Cerebral palsy in children and its relationship with perinatal medical care].

We studied the etiology of 76 children with cerebral palsy (CP) aged 3 to 6 years, who visited the Himeji City Center for the Handicapped for neurological follow up. The patients for this study composed of 30 cases with severe handicap. 8 cases of CP with mental retardation and 10 cases of CP without mental retardation. Nine cases of CP had congenital anomalies of central nervous system, of which 8 cases showed severe handicap. Main perinatal factors were asphyxia, dyspneic condition needed for mechanical ventilation, prolonged apneic spells, and hyperbilirubinemia. All full-term birth children were accompanied with asphyxia, in which 43% had intracranial hemorrhage. A cooperative network between neonatal intensive care unit and an institute for the handicapped is essential for the care of infants with cerebral palsy.

Cerebral Palsy↗
PubMed1993

Bactericidal effects of povidone-iodine solution to oral pathogenic bacteria in vitro.

Seven species of periodontal pathogenic bacteria (Bacteroides, gingivalis, Bacteroides intermedius, Bacteroides melaninogenicus, Fusobacterium nucleatum, Actinobacillus actinomycetemcomitans, Capnocytophaga spp., Eikenella corrodens) and two control species (Streptococcus intermedius, Pseudomonas aeruginosa) were selected in order to study the bactericidal effects of 10% povidone-iodine (PVP-I) aqueous solution in vitro. The PVP-I solution was diluted to 10, 20, 50, 100, 200, 400, 800, 1600, 3200, 6400 and 12800 x and contact times were 15, 30 and 60 seconds. The strongest bactericidal effects on the seven periodontal pathogenic bacteria and two control bacteria were seen at a dilution of 400 x and a contact time of 15 seconds. Based on these findings, we advocate a 0.25% solution of 10% aqueous PVP-I for oral mucosa and periodontal pocket irrigation.

Aggregatibacter actinomycetemcomitans↗
PubMed1993

[IgE-receptor stimulation induces biphasic 1,2-diacylglycerol production in RBL-2H3 cells. Phosphatidylcholine hydrolysis by phospholipase D plays a major role in the second sustained 1,2-diacylglycerol accumulation].

Activation of RBL-2H3 cells by cross-linking their IgE receptors resulted in a biphasic increase in cellular 1,2-diacylglycerol (DG) content. The first-phase DG production was coincident with a transient breakdown of phosphatidylinositol 4,5-bisphosphate (PIP2). The second large sustained phase of DG accumulation appeared to be derived mainly from phosphatidylcholine (PC) and partly from phosphatidylinositol (PI). The accumulation of phosphatidylethanol (PEt) and the reduction of DG formation in the presence of ethanol suggested that more than 50% of the DG due to PC hydrolysis was formed through the action of phospholipase D. The addition of phorbol myristate acetate or Ca2+ ionophore A23187 stimulated the hydrolysis of PC. In protein kinase C (PKC) down-regulated cells, PC hydrolysis induced by A23187 was markedly suppressed. Taken together, these results lead as to speculate that hydrolysis of PC is regulated by the increase in cellular Ca2+ and PKC activation through the hydrolysis of PIP2. The exocytotic response became evident with a 1 min time lag after antigen (Ag) stimulation, followed by the transient breakdown of PIP2. Ethanol inhibited Ag-stimulated serotonin secretion. The concentration-dependent inhibitory profile of secretion by ethanol correlated well with that of the sustained phase of DG accumulation. These results suggest that sustained DG production, mainly derived from PC through phospholipase D action, plays an important role in maintaining secretory response.

Animals↗
PubMed1992

Morphological changes in liposomes caused by polymerization of encapsulated actin and spontaneous formation of actin bundles.

Spherical giant liposomes that had encapsulated skeletal-muscle G-actin were made by swelling a dried lipid mixture of dimyristoyl phosphatidylcholine/cardiolipin, 1:1 (wt/wt), in a solution of G-actin/CaCl2 at 0 degree C. Polymerization of the encapsulated G-actin into actin filaments was achieved by raising the temperature to 30 degrees C. We observed the subsequent shape changes of the liposomes by dark-field and differential interference-contrast light microscopy. After approximately 40 min, which was required for completion of actin polymerization, two shapes of liposome were evident: dumbbell and disk. Elongation of the dumbbell-shaped liposomes was concomitant with actin polymerization. Polarization microscopy showed that actin filaments formed thick bundles in the liposomes and that these filaments lay contiguous to the periphery of the liposome. Localization of actin filaments in the liposomes was confirmed by observation of rhodamine phalloidin-conjugated actin filaments by fluorescence microscopy. Both dumbbell- and disk-shaped liposomes were rigid and kept their shapes as far as actin filaments were stabilized. In contrast, liposomes containing bovine serum albumin were fragile, and their shapes continually fluctuated from Brownian motion, indicating that the actin bundles served as mechanical support for the liposome shapes.

Actin Cytoskeleton↗
PubMed1992

Relationship between soma diameter and oxidative enzyme activity of alpha-motoneurons.

In order to determine whether there is a relationship between soma diameter and oxidative enzyme activity of alpha-motoneurons, we investigated the alpha-motoneurons innervating the different portions within a rat gluteus medius muscle. Two fluorescent neuronal tracers, Nuclear yellow and Fast blue, were used for labeling motoneurons innervating the deep (predominance of oxidative fibers) and superficial (predominance of non-oxidative fibers) portions of the muscle. An inverse relationship between soma diameter and oxidative enzyme activity was not seen in the motoneuron pool innervating either the deep or superficial portions. When the two portions were taken together, however, the inverse relationship was seen. The inverse relationship seemed to be demonstrated in a motoneuron pool which intermingled motoneurons innervating oxidative fibers and motoneurons innervating non-oxidative fibers. These results suggest that the oxidative enzyme activity of alpha-motoneurons is not correlated strictly with their soma size. We consider that the oxidative enzyme activity of alpha-motoneurons is correlated with oxidative enzyme activity of the muscle unit.

Amidines↗
PubMed1992

Study of low molecular weight heparin effect on the relation between anticoagulant activity and antithrombin III affinity.

Low molecular weight heparin (FR-860), and conventional unfractionated heparin (UF-heparin) were fractionated by rabbit antithrombin III (AT III)-Sepharose, and the effects of each affinity fraction on the coagulation and fibrinolytic activities were investigated. FR-860 was fractionated to no-affinity, low-affinity (LA) and high-affinity (HA) fractions, and UF-heparin to LA and HA fractions. The HA fractions showed higher activities regarding the prolongation of activated partial thromboplastin time, anti-factor Xa activity and antithrombin activity compared with those of LA. The HA and LA fractions exhibited the enhancement of heparin cofactor II (HC II) activity and fibrinolytic activity in a dose-dependent manner. These results suggest that the antithrombotic activity of FR-860 is exerted through AT III and other mechanism such as HC II-mediated system.

Animals↗
PubMed1992

Study of anticoagulant mechanism of low molecular weight heparin.

The binding ability of low molecular weight heparin (FR-860), and conventional unfractionated heparin (UF-heparin) to factor Xa (F.Xa), thrombin and AT III was investigated using FR-860- and UF-heparin-Sepharoses. FR-860 could not bind directly to F.Xa. FR-860 bound to thrombin and AT III with stronger affinity to AT III than to thrombin. On the other hand, UF-heparin bound to F.Xa, thrombin and AT III with the strongest affinity to AT III followed by thrombin and F.Xa. AT III mediated the binding between F.Xa and FR-860 and accelerated the reaction between F.Xa and UF-heparin. On the other hand, AT III did not affect the binding between thrombin and FR-860 or UF-heparin. Diisopropyl fluorophosphate-treated thrombin inhibited the binding between AT III and FR-860, but not that between AT III and UF-heparin. These results suggest that the anti-F.Xa activity of FR-860 is mediated by AT III. Furthermore, the difference of antithrombin activity between FR-860 and UF-heparin depends on the capability to form ternary complex of FR-860 or UF-heparin, AT III and thrombin.

Animals↗
PubMed1992

Cytosolic Ca2+ concentration and pH of diabetic rat myocytes during metabolic inhibition.

To investigate the role of Ca2+ metabolism and pH in diabetic cardiomyopathy, intracellular Ca2+ concentration ([Ca2+]i) and intracellular pH (pHi) of isolated myocytes were measured simultaneously using fura-2 and BCECF. We used diabetic (D.M.) rats at 8 weeks after the injection of streptozotocin (45 mg/kg, i.v.). (1) [Ca2+]i of D.M. myocytes was lower than that of controls (53 +/- 3 and 75 +/- 5 nM, mean +/- S.E., P less than 0.01). There was no difference in pHi (7.06 +/- 0.02 in D. M., 7.07 +/- 0.02 in control). There was no difference in the percentage of non-rounded cells at 30 min after the perfusion of glucose-free solution which contained 2 mM sodium cyanide (NaCN) between D.M. and controls (53% and 52%). When cells were rounded, the value of [Ca2+]i was significantly lower in D.M. myocytes than that in controls (172 +/- 21 and 421 +/- 106 nM, P less than 0.05). (2) When the cells were shortened or rounded in the high [Ca2+]o solution (24.5 mM), [Ca2+]i of D.M. rats was significantly lower than that of control rats. (3) The percentage of non-rounded cells at 30 min after the perfusion of NaCN increased in controls by 50 mM glucose (95%, P less than 0.01), but not in D.M. (47%). Insulin (25 mU/ml) and glucose (15 mM) increased the percentage of non-rounded cells in D.M. after 30 min perfusion with NaCN (88%, P less than 0.01 v.s. 53% without glucose nor insulin). It is suggested that there are disturbances of Ca2+ metabolism in D.M. myocytes, and that there is a close relation between cell injury and glucose utilization during metabolic inhibition.

Animals↗
PubMed1992

Myosin heavy chain isoform transition in ageing fast and slow muscles of the rat.

Using gradient sodium dodecyl sulphate-polyacrylamide gel electrophoresis, myosin heavy chain (MHC) isoforms were studied in the extensor digitorum longus (EDL) and the soleus muscles of male Wistar rats at different ages (5, 10, 20 weeks, 1 and 2 years). In the EDL muscle, four types of MHC isoforms were observed in all age groups. There was an increase in the percentage of HCIId and a concomitant decrease in the percentage of HCIIb with increasing age. No significant difference was observed in the percentages of HCI and HCIIa isoforms in all the age groups. In contrast, the soleus muscle contained two MHC isoforms, HCI and HCIIa. There was an increase in the percentage of HCI and a concomitant decrease in the percentage of HCIIa with increasing age. These results suggest that age-related changes in the MHC isoforms in both the fast-twitch EDL and the slow-twitch soleus muscles are one factor underlying the age-related decrease in the speed of muscle contraction.

Aging↗