Biomedical subjects

M Asakawa

Publications and source records attributed to M Asakawa.

At least 19 recordsLinked to original sources

PubMed2001

Seroprevalence of Borna disease virus in domestic animals in Xinjiang, China.

To investigate the animals infected with Borna disease virus (BDV) in Xinjiang, China, we examined for BDV antibodies in the sera from groups of 20 horses, sheep and cattle, and from 165 wild rodents (18 species) by ELISA and immunoblot. The serological study disclosed the presence of antibodies to both BDV-p24 and -p40 in the horses (20%) and sheep (25%), whereas no apparent positive reaction was detected either in cattle or rodents. The results suggested that BDV is prevalent in horses and sheep in the district investigated.

Animals↗

PubMed2001

Doppler-shifted cyclotron absorption of electron Bernstein waves via N( parallel)-upshift in a Tokamak plasma.

Extraordinary (X) waves are perpendicularly injected for electron Bernstein (B) wave heating into an Ohmically heated plasma from the inboard side in the WT-3 tokamak. Measurements show that absorption does not take place at the electron cyclotron resonance layer nor the upper hybrid resonance layer, but does happen midway between them. This is consistent with the ray tracing prediction, i.e., the poloidal field and poloidal inhomogeneity of toroidal field lead the B waves to have a large parallel refractive index N( parallel) (>1), and the B waves are damped away via the Doppler-shifted cyclotron resonance.

Journal Article↗

PubMed2001

Purification and identification of N-glycolylneuraminic acid (Neu5Gc) from the holothuroidea Gumi, Cucumaria echinata.

N-Glycolylneuraminic acid (Neu5Gc), precious sialic acid which could not be synthesized by a chemical method, occurrs in the body of holothuroidea, Gumi Cucumaria echinata. Gumi contains 85% of total sialic acid, as Neu5Gc, in the body. Neu5Gc was purified from dry powder of the body using Dowex 1-x8 (HCOO* form) anion exchange chromatography after mild acid hydrolysis with 0.1 N trifluoroacetic acid. Using GC-MS and 1H-NMR spectroscopy, the purified Neu5Gc was correctly identified to be Neu5Gc. The purity of Neu5Gc was more than 99%. This is the first report of purification and identification of Neu5Gc from holothuroidea by using anion exchange chromatography, GC-MS, and 1H-NMR.

Animals↗

PubMed2001

Anthracycline-induced cardiomyopathies evaluated by tissue Doppler tracking system and strain rate imaging.

OBJECTIVES: Anthracycline cardiotoxicity is known to occur from the subendocardial side of the left ventricular wall. Recent advances of tissue Doppler echocardiography may allow the evaluation of anthracycline cardiotoxicity by dividing the left ventricular wall into the subendocardial half and subepicardial half. The present study assessed the feasibility using the tissue Doppler echo tracking system (M-mode) and myocardial strain rate imaging (B-mode) to noninvasively detect anthracycline cardiotoxicity. METHODS: The tissue Doppler echo tracking system (M-mode) was used to measure systolic thickening of the subendocardial layer (delta Endo), subepicardial layer (delta Epi), and whole wall (delta Total) of the left ventricular posterior wall in 41 normal subjects and three groups of patients receiving anthracycline: 34 patients in the low dose group, 19 in the middle dose group, and 12 in the high dose group. Strain rate is the spatial gradient of local velocities, reflecting local compression and expansion rates not affected by overall heart motion. Myocardial strain rate imaging (B-mode) was used in 25 normal subjects, 9 patients in the low dose group, and 10 patients in the high dose group. The ratio of peak systolic strain rate of subendocardium to that of subepicardium (peak strain rate endo/epi), and the ratio of integrated strain rate during ejection time of subendocardium to that of subepicardium (integrated strain rate endo/epi) were measured. RESULTS: Tissue Doppler echo tracking system (M-mode) measurement of delta Endo/delta Epi showed the most distinct difference and the least overlap of the data between normal subjects and patients, whereas delta Total failed to show significant differences. Myocardial strain rate imaging (B-mode) measurement of integrated strain rate endo/epi showed the most distinct difference and the least overlap of the data between normal subjects and patients, but ejection fraction failed to show statistically significant differences. CONCLUSIONS: These methods are highly sensitive tools for monitoring anthracycline cardiotoxicity.

Anthracyclines↗

PubMed2001

[A case of choroidal hemangioma with bullous exudative retinal detachment treated successfully by transpupillary thermotherapy].

BACKGROUND: Choroidal hemangioma associated with bullous retinal detachment may be difficult to treat, due to varying results with conventional laser photocoagulation, radiotherapy, or surgical drainage. Here we report on a case of extensive bullous retinal detachment secondary to circumscribed choroidal hemangioma that was resolved after combined treatment with vitrectomy, silicone oil tamponade, and transpupillary thermotherapy. CASE: A 29-year-old woman presented with a large choroidal hemangioma in her right eye associated with serous retinal detachment. The tumor measured 8 disc diameters in size and was located in the inferotemporal macula, abutting the fovea. RESULTS: Laser photocoagulation of the tumor was unsuccessful in inducing absorption of subretinal fluid. Because of progressive bullous retinal detachment, surgery was performed consisting of external drainage of subretinal fluid, vitrectomy, endolaser photocoagulation of the tumor, and silicone oil tamponade. The silicone oil was removed four weeks postoperatively at which time almost complete resolution of the retinal detachment was observed. However, retinal detachment recurred eight weeks later, and transpupillary thermotherapy was then applied to the tumor. By four weeks after transpupillary thermotherapy, total reabsorption of subretinal fluid, visual acuity improvement, and decreased height of the choroidal hemangioma were noted. CONCLUSION: Transpupillary thermotherapy is an effective treatment for serous retinal detachment associated with choroidal hemangioma.

Adult↗

PubMed2000

Peroxisome proliferator-activated receptor activators inhibit lipopolysaccharide-induced tumor necrosis factor-alpha expression in neonatal rat cardiac myocytes.

Peroxisome proliferator-activated receptors (PPARs) are transcription factors belonging to the nuclear receptor superfamily. Recently, PPAR activators have been shown to inhibit the production of proinflammatory cytokines in macrophages or vascular smooth muscle cells. It has been reported that tumor necrosis factor-alpha (TNF-alpha) expression is elevated in the failing heart and that TNF-alpha has a negative inotropic effect on cardiac myocytes. Therefore, we examined the effects of PPARalpha and PPARgamma activators on expression of TNF-alpha in neonatal rat cardiac myocytes. Northern blot analysis revealed expression of PPARalpha and PPARgamma mRNA in cardiac myocytes. Immunofluorescent staining demonstrated that both PPARalpha and PPARgamma were expressed in the nuclei of cells. When cardiac myocytes were transfected with PPAR responsive element (PPRE)-luciferase reporter plasmid, both PPARalpha and PPARgamma activators increased the promoter activity. Cardiomyocytes were stimulated with lipopolysaccharide (LPS), and the levels of TNF-alpha in the medium were measured by ELISA. After exposure to LPS, the levels of TNF-alpha significantly increased. However, pretreatment of myocytes with PPARalpha or PPARgamma activators decreased LPS-induced expression of TNF-alpha in the medium. Both PPARalpha and PPARgamma activators also inhibited LPS-induced increase in TNF-alpha mRNA in myocytes. In addition, electrophoretic mobility shift assays demonstrated that PPAR activators reduced LPS-induced nuclear factor-kappaB activation. These results suggest that both PPARalpha and PPARgamma activators inhibit cardiac expression of TNF-alpha in part by antagonizing nuclear factor-kappaB activity and that treatment with PPAR activators may lead to improvement in congestive heart failure.

Animals↗

PubMed2000

Fluctuation probes of quark deconfinement

The size of the average fluctuations of net baryon number and electric charge in a finite volume of hadronic matter differs widely between the confined and deconfined phases. These differences may be exploited as indicators of the formation of a quark-gluon plasma in relativistic heavy-ion collisions, because fluctuations created in the initial state survive until freeze-out due to the rapid expansion of the hot fireball.

Journal Article↗

PubMed2000

Paralytic toxins in a ribbon worm Cephalothrix species (Nemertean) adherent to cultured oysters in Hiroshima Bay, Hiroshima Prefecture, Japan.

In 1998, during the surveillance of the toxicity of various marine fouling organisms in Hiroshima Bay, Hiroshima Prefecture, Japan, specimens of the ribbon worm, "himomushi" Cephalothrix sp. (Nemertean) adherent to the shells of cultured oysters hanging onto floating culture rafts were found to contain toxins which showed strong paralytic action in mice throughout the survey period, February to May. The maximum toxicity (as tetrodotoxin, TTX) was 14,734 MU/g whole body. Attempts were made to identify the paralytic toxins in this worm. The "himomushi" toxin (HMT) was extracted from the worm with 80% methanol acidified with acetic acid and the extract defatted with dichloromethane. The aqueous layer was chromatographed on activated charcoal and the unbound and bound toxic fractions were analyzed by high-performance liquid chromatography and gas chromatography-mass spectrometry. It was rather unexpectedly revealed from these results that HMT was comprised of TTX, 4-epiTTX, anhydroTTX and three unidentified toxins. To our knowledge, this is the first report of the occurrence of toxic organisms, containing a high concentration of TTX, adherent to cultured bivalves such as oysters.

Animals↗

PubMed2000

Viral mutation accelerated by nitric oxide production during infection in vivo.

Nitric oxide (NO), superoxide (O(2)(-)), and their reaction product peroxynitrite (ONOO(-)) are generated in excess during a host's response against viral infection, and contribute to viral pathogenesis by promoting oxidative stress and tissue injury. Here we demonstrate that NO and peroxynitrite greatly accelerates the mutation of Sendai virus (SeV), a nonsegmented negative-strand RNA virus, by using green fluorescent protein (GFP) inserted into and expressed by a recombinant SeV (GFP-SeV) as an indicator for mutation. GFP-SeV mutation frequencies were much higher in the wild-type mice than in those lacking inducible NO synthase, suggesting that mutation of the virus in vivo is NO dependent. High levels of NO and NO-mediated oxidative stress were induced by GFP-SeV infection in the lung of the wild-type mice, but not in the iNOS-deficient mice, as evidenced by electron spin resonance spectroscopy and immunohistochemical analysis for nitrotyrosine formation as well as histopathological examination. Furthermore, peroxynitrite, an NO-derived reactive nitrogen intermediate, enhanced viral mutation in vitro. These results indicate that the oxidative stress induced by NO produced during the natural course of viral infection increases mutation, expands the quasispecies spectrum, and facilitates evolution of RNA viruses.

Animals↗

PubMed2000

A cytoplasmic RNA vector derived from nontransmissible Sendai virus with efficient gene transfer and expression.

We have recovered a virion from defective cDNA of Sendai virus (SeV) that is capable of self-replication but incapable of transmissible-virion production. This virion delivers and expresses foreign genes in infected cells, and this is the first report of a gene expression vector derived from a defective viral genome of the Paramyxoviridae. First, functional ribonucleoprotein complexes (RNPs) were recovered from SeV cloned cDNA defective in the F (envelope fusion protein) gene, in the presence of plasmids expressing nucleocapsid protein and viral RNA polymerase. Then the RNPs were transfected to the cells inducibly expressing F protein. Virion-like particles thus obtained had a titer of 0.5 x 10(8) to 1. 0 x 10(8) cell infectious units/ml and contained F-defective RNA genome. This defective vector amplified specifically in an F-expressing packaging cell line in a trypsin-dependent manner but did not spread to F-nonexpressing cells. This vector infected and expressed an enhanced green fluorescent protein reporter gene in various types of animal and human cells, including nondividing cells, with high efficiency. These results suggest that this vector has great potential for use in human gene therapy and vaccine delivery systems.

Animals↗

PubMed2000

Green fluorescent protein gene insertion of Sendai Virus infection in nude mice: possibility as an infection tracer.

The green fluorescent protein (GFP) marker from jellyfish Aequorea victoria is considered to have potential use in the study of host-pathogen relationships, by tracing infections in living cells, organs and animals. We compared the pathogenicity of Sendai virus with an inserted GFP gene (GFP-SeV) with that of its wild-type (Wt-SeV) to determine the usefulness of the recombinant virus in long-term infection of BALB/c nude (nu/nu) mice. The results indicated that the presence of GFP in infected cells could be analyzed easily and sensitively. GFP helped in identifying and in understanding the cellular sites of viral replication in vitro and in vivo. However, the GFP insertion into the Wt-SeV genome, led to decreased pathogenicity, altering the in vivo viral kinetics.

Animals↗

PubMed2000

[A morphological study of the kidney in the Japanese fetus with special reference to their external form, size and number of minor calix].

There are few anatomical reports on the fetal kidney than on adult human and animal kidneys. This paper reports the size, weight, ratio of renal hilus, number of minor calix and number of renal lobe in Japanese fetal kidneys. Fifty kidneys of 25 fetuses (3, 8, 8 and 6 bodies in 5, 6, 7 and 8 months, respectively) were used in this study. The length, width, thickness and weight of kidneys were measured, and the renal lobes were counted. The relative size of the hilus was then calculated by the ratio of the area of hilus to that of the medial surface of the kidneys. Latex rubber was injected in the ureters, taken out of the calico-pelvic system from the kidneys, and the number of minor calix in these specimens were counted. There were no significant sex difference and right and left difference in the kidney weight, ratio of renal hilus, number of minor calix and number of lobes. When these kidneys were observed at 5, 6, 7 and 8 months, the kidney weight and ratio of renal hilus were correlated with fetal age, but the numbers of lobe and minor calix were not. Comparing the results mentioned above with those of adult kidneys, it was shown that kidney weight and ratio of renal hilus area to the medial surface area of the kidneys gradually increased from fetus to adult. There was also a significant difference in the number of minor calix between adult and fetal kidneys. There was no correlation between the number of renal lobe and the number of minor calix.

Adult↗

PubMed1999

Accommodation of foreign genes into the Sendai virus genome: sizes of inserted genes and viral replication.

Sendai virus (SeV) is an enveloped virus with a negative sense genome RNA of about 15.3 kb. We previously established a system to recover an infectious virus entirely from SeV cDNA and illustrated the feasibility of using SeV as a novel expression vector. Here, we have attempted to insert a series of foreign genes into SeV of different lengths to learn how far SeV can accommodate extra genes and how the length of inserted genes affects viral replication in cells cultured in vitro and in the natural host, mice. We show that a gene up to 3.2 kb can be inserted and efficiently expressed and that the replication speed as well as the final virus titers in cell culture are proportionally reduced as the inserted gene length increases. In vivo, such a size-dependent effect was not very clear but a remarkably attenuated replication and pathogenicity were generally seen. Our data further confirmed reinforcement of foreign gene expression in vitro from the V(-) version of SeV in which the accessory V gene had been knocked out. Based on these results, we discuss the utility of SeV vector in terms of both efficiency and safety.

Animals↗

PubMed1999

The RAMP2/CRLR complex is a functional adrenomedullin receptor in human endothelial and vascular smooth muscle cells.

Adrenomedullin, a potently hypotensive peptide isolated from human pheochromocytoma, is known to elicit a rise in cAMP levels within mammalian endothelial and smooth muscle cells. Until now, however, little has been known about the adrenomedullin receptor. Recently, a group called receptor activity-modifying proteins that complex with the calcitonin receptor-like receptor, and thereby regulate its transport and ligand specificity, were identified. Here we show that mRNA for both the calcitonin receptor-like receptor and the receptor activity-modifying protein 2, but not the receptor activity-modifying protein 1 or receptor activity-modifying protein 3, are expressed in human endothelial and vascular smooth muscle cells. We also found that adrenomedullin increased cAMP levels in HeLa EBNA and 293 EBNA cells, expressing both the receptor activity-modifying protein 2 and calcitonin receptor-like receptor proteins. Thus, the receptor activity-modifying protein 2/calcitonin receptor-like receptor complex apparently serves as a functional adrenomedullin receptor in human endothelial and vascular smooth muscle cells.

Adrenomedullin↗

PubMed1999

First report of Thelazia sp. from a captive Oriental white stork (Ciconia boyciana) in Japan.

Nematodes of the genus Thelazia were recovered from the cornea and inferior conjunctival sac of an immature Oriental white stork (Ciconia boyciana). The bird hatched and reared at the Toyooka Oriental White Stork Breeding Center, Hyogo Prefecture, Japan, but died of chlamydiosis. There were neither gross nor histopathologic ophthalmic lesions. The eye worm from a bird is believed to be first reported in Japan. As regarding reintroduction plan for the Oriental white stork, control measures for prevent further infection with the eye worm will be needed.

Animals↗

PubMed1998

Measles virus attenuation associated with transcriptional impediment and a few amino acid changes in the polymerase and accessory proteins.

Measles virus (MV) isolated in B95a cells, a marmoset B-cell line, retains full pathogenicity for cynomolgus monkeys, while its derivative obtained by adaptation to the growth in Vero cells, a monkey kidney cell line, loses the pathogenic potential (F. Kobune, H. Sakata, and A. Sugiura, J. Virol. 64:700-705, 1990). Here, we show with a pair of strains, a fresh isolate (9301B) in B95a cells and its Vero cell-adapted form (9301V), that the in vivo attenuation parallels the decrease of replication and syncytium-inducing capabilities in the original B95a cells and that these in vitro phenotypes are attributable to impediment of transcription, which is already obvious at the level of primary transcription catalyzed by the virion-associated RNA polymerase. On the other hand, cell fusion assays detected no functional difference between the glycoproteins of the two viruses. Essentially the same transcriptional impediment with reduced syncytium induction following Vero cell adaptation was found with two other pairs of strains that had been similarly prepared. Nucleotide sequence comparison between the 9301B and 9301V viruses revealed that a few (at most five) amino acid changes, which sporadically took place in the polymerase (L and P proteins) and/or accessory V and C proteins, were responsible for the in vitro and in vivo attenuation through adaptation to growth in Vero cells.

Adaptation, Physiological↗

PubMed1998

[Left ventricular wall motion dynamics of asymmetric septal hypertrophy: assessment by intramyocardial pulsed Doppler echocardiography].

Apical pulsed Doppler tissue imaging can be used to assess the function of regional myocardium. We hypothesized that septal dysfunction might be clarified in the hypertrophic cardiomyopathy (asymmetric septal hypertrophy) by this method. Twenty-one patients with asymmetric septal hypertrophy (mean age 54.8 +/- 11 years) and age-matched 24 normal subjects (52.4 +/- 8 years) were studied. The E/A ratio measured by mitral inflow Doppler was not different between the groups (1.1 vs 1.2). E wave velocities of the septum were significantly decreased in the hypertrophy group compared to the control group (4.0 +/- 1.5 vs 8.1 +/- 2.2 cm/sec), and A wave velocities were increased in the hypertrophic septum, resulting in a significantly lower E/A ratio (0.5 +/- 0.3) compared to the E/A ratio (0.9 +/- 0.3) of the normal septum. Deceleration time of the E wave and isovolumic relaxation time were significantly prolonged in the thick septum compared to the normal septum (136 +/- 51 vs 107 +/- 28 msec, 91 +/- 36 vs 63 +/- 19 msec, respectively). In conclusion, asymmetric septal hypertrophy was characterized by diastolic dysfunction of the thickened septum. Intramyocardial pulsed Doppler echocardiography can detect regional myocardial dysfunction earlier than the mitral inflow Doppler method.

Cardiomyopathy, Hypertrophic↗

PubMed1998

[Ebstein's anomaly associated with left ventricular dysfunction: a case report].

A 66-year-old man presented with Ebstein's anomaly associated with left ventricular dysfunction. He had been followed since 40 years of age for cardiomegaly and arrhythmia, and experienced episodes of orthopnea at the age of 64. He was referred to our hospital in April 1997 because of lower extremity edema. Physical examination revealed dilated external jugular vein, tenderness of the right hypocondorium, and lower extremity edema. Electrocardiography confirmed atrial fibrillation. Transthoracic echocardiography revealed bilateral atrial and ventricular dilation, and paradoxical septal movement. The apical four-chamber view demonstrated 15 mm apical displacement of the septal leaflet. Color Doppler echocardiography revealed moderate tricuspid regurgitation. Transesophageal echocardiography revealed low echoic and hypoplastic tricuspid valve. Left ventriculography showed diffuse hypokinesis, and the ejection fraction was 49%. The coronary artery was normal. Atrial septal defect was not detected. Diffuse fibrosis, which may be found in the hearts of patients with Ebstein's anomaly at autopsy may have been responsible for the left ventricular depressed systolic function in this patient.

Aged↗