Biomedical subjects

T Imagawa

Publications and source records attributed to T Imagawa.

At least 37 records · Page 2Linked to original sources

PubMed2001

Effects of adrenergic agonists on glycogenolysis in primary cultures of glycogen body cells and telencephalon astrocytes of the chick.

The glycogen body (GB) is at the dorsal area of the lumbosacral spinal cord in birds and is composed of uniform cells that are characterized by high-glycogen storage. Previous morphological and embryological examinations suggest that the GB is derived from the neuroepithelium and contains many blood vessels and a few nerve fibers. However, the function of the GB and role of the glycogen are unknown. Mammalian astrocytes are major sites for glycogen stores in the central nervous system. The metabolic features of astrocytes have been defined by using cultured cells. As a first step toward investigating the function of GB, we established primary culture of chicken GB cells and telencephalon astrocytes. The cultured GB cells maintained high glycogen content and glial fibrillary acidic protein (GFAP) in the cytoplasm. The glycogen content of GB cells significantly increased with the glucose concentration in the medium. The effects of adrenergic agonists on glycogenolysis were different between GB cells and telencephalon astrocytes. The telencephalon astrocytes shared similar characteristics of glycogenolysis with mouse astrocytes, which are mainly affected by beta adrenergic receptor. Although GB cells were affected by noradrenalin (both alpha and beta adrenergic agonist), they were not affected by beta adrenergic agonist. These results showed that cultured GB cells were considered as one lineage of astrocytes because of their reactivity to antibody against GFAP; however, the metabolic features of GB cells were different from those of telencephalon astrocytes.

Adrenergic Agonists↗

PubMed2001

Distribution of reticulocerebellar neurons in chicken reticular formation.

The distribution of reticulocerebellar (RC) neurons was examined by the retrograde transport of horseradish peroxidase (HRP) or wheat germ agglutinin bound to HRP (WGA-HRP) in 7 White Leghorn chickens. A large number of labeled cells were found in the nucleus reticularis pontis caudalis (RP) of the pontomedullary junction and in the nucleus reticularis gigantocellularis (Rgc), parvocellularis (Rpc), subtrigiminalis (Rst), paragigantocellularis (Rpg) and paramedianus (RpaM) in the medulla. Slightly ventral to the vestibulocochlear nerve were many large RC neurons arranged in a longitudinal manner along the lateral edge of the brainstem reticular formation (the Dorsolateral edge cells, DLe cells). RC neurons were most numerous in the Rgc and accounted for 31.9% of the total number of labeled cells, followed by RP (24.2%), Rpc (12.7%), Rpg (10.8%), RpaM (6.7%), DLe cells (6.3%) and Rst (4.9%). The great number of RC neurons was found around the levels of the vestibulocochlear nerve.

Animals↗

PubMed2000

On the mechanism of protection of distal joints after local gene transfer in collagen-induced arthritis.

Considerable interest has been generated by the observation that adenovirus-mediated gene delivery to a single arthritic joint results in suppression of arthritis in distal joints associated with the presence of small numbers of transduced cells in distal joints. It has been proposed that this is mediated by trafficking of transduced cells from the injected to distal joints. There are, however, alternative explanations that have not been explored, including the possibility that transgene protein or infectious virions circulate to distal sites. To investigate these possibilities, a replication-incompetent adenovirus encoding viral IL-10 (vIL-10) was administered to naive mice and to mice with collagen-induced arthritis by intraarticular, periarticular, or intravenous injection. In all cases, the ability to protect distal joints correlated with serum levels of vIL-10 protein. After intraarticular or intravenous injection, vIL-10 cDNA could be detected not only in distal joints, but also in the liver, which is the major target of circulating adenovirus, demonstrating that adenovirus circulating through the bloodstream is taken up by the joint tissue. Periarticular administration of adenovirus, which resulted in lower serum levels of vIL-10, protected only the injected paws and failed to induce trafficking immunoregulatory cells capable of suppressing distal disease. These observations suggest that circulating vIL-10 protein is the major mediator of distal protection. The presence of small numbers of transduced cells at distal sites can be accounted for by transduction of distal synovium after entry of adenovirus virions into the circulation.

Adenoviridae↗

PubMed2000

Developmental study of the shortened spinal cord in the adult tiger puffer fish, Takifugu rubripes (Teleostei).

ABSTRACT The spinal cords of vertebrates are generally divided into the cord proper and the minute filum terminale. While the spinal cord extends the entire length of the vertebral canal in the adult tiger puffer, Takifugu rubripes, the cord proper is greatly reduced in length and almost all of the canal is occupied by the filum terminale, which is tape-like rather than thread-like. The dorsal and ventral roots of the spinal nerves extend, respectively, above and below the filum terminale; as a whole, these form a massive cauda equina. Supramedullary cells are found in the rostral half of the medulla oblongata caudal to the cerebellum. In 4-mm long tiger puffers, the spinal cord is cylindrical and supramedullary cells are found in the rostral half of the cord. In 7-mm puffers, the longitudinally arranged ventral roots appear ventrally in the middle portion of the spinal cord. In 15-mm puffers, the dorsal and ventral roots run longitudinally along the spinal cord and have noticeably increased in number. Supramedullary cells are located in the rostral 15% of the cord. In 21-mm puffers, the spinal cord in large part becomes dorsoventrally flattened. In 30-mm puffers, the spinal cord becomes much flatter, and supramedullary cells now are located mainly in the medulla oblongata. These observations indicate that formation of the shortened spinal cord proper is due to at least two developmental processes. First, the elongation of the spinal cord proper is remarkably less than that of the vertebral canal. Second, the bulk of the spinal cord proper is translocated to the cranial cavity, where it is transformed into part of the medulla oblongata.

Animals↗

PubMed2000

Oka varicella vaccine is distinguishable from its parental virus in DNA sequence of open reading frame 62 and its transactivation activity.

When the nucleotide sequences of the Oka vaccine and its parental varicella-zoster virus (VZV) were compared in 6 open reading frames (ORFs), glycoprotein C (gC) and 5 transactivator genes, mutations were detected only in the immediate-early gene 62. The vaccine virus contained a mixture of different sequences that had variations at 15 nucleotide positions, but only one sequence was found for the Oka parental virus gene 62. The Oka vaccine virus gene 62 could be distinguished from the parental virus gene using a simplified restriction-enzyme fragment length polymorphism analysis, using NaeI and BssHII. This analysis was based on the sequence data obtained in this study. Studies of the regulatory activities of the ORF62 gene product (IE62) in a transient transfection assay indicated that IE62 of the parental virus had a stronger transactivational activity than that of the vaccine virus in activating immediate-early, early, and late gene promoters. These data suggest that IE62 might play an important role in the attenuation of VZV.

Cells, Cultured↗

PubMed2000

Adeno-associated virus mediates long-term gene transfer and delivery of chondroprotective IL-4 to murine synovium.

Treatments for rheumatoid arthritis and other inflammatory arthropathies are often ineffective at preventing joint destruction. Long-term genetic modification of the cells lining the joint space (synoviocytes) in vivo represents a potential method for the treatment of these chronic conditions. However, a vector capable of efficiently transducing synoviocytes in vivo for a persistent period has not been available. The present report describes the genetic modification of synoviocytes in vivo using recombinant adeno-associated virus. High-titer adeno-associated virus encoding the gene for Escherichia coli beta-galactosidase was injected into the knee joints of mice. Synovial tissues were then examined for beta-galactosidase transgene expression by in situ staining and by fluorometry. High-efficiency, persistent transgene expression was observed in the synovium with no evidence of vector-induced inflammation. Expression was observed for at least 7 months and was higher in arthritic than nonarthritic mice. Gene transfer of murine IL-4 to the joints of mice with collagen-induced arthritis led to detectable levels of IL-4 in the joint and protection from articular cartilage destruction. These data suggest that adeno-associated virus may be a useful vector for gene delivery to the synovium for the treatment of inflammatory arthropathies.

Animals↗

PubMed2000

The organization of the spinocerebellar tract neurons in the chicken.

The organization of spinocerebellar tract (SCT) neurons in the chicken was studied quantitatively using retrograde wheat germ agglutinin-horseradish peroxidase labelling. The chicken spinal cord was divided into five regions based on the distribution of SCT neurons: the cervical region (the spinal segments [SS], 1-12, which contained 32% of the total number of SCT neurons), the cervical enlargement (SS13-15, 13.4%), the thoracic region (SS16-20, 13%), the thoraco-lumbosacral region (SS21-26, 34.6%), and the posterior lumbosacral region (SS27-30, 7%). Clarke's column was found in two regions, a cervical one (SS12-16) and a lumbar one (SS21-28). The spinal border cells were less numerous and also present in two parts, a cervical one (SS10-15) and a caudal one (SS20-24). SCT neurons of the ventral part of the ventral horn were found in the cervical enlargement and SS16 (lamina VIII), and in the thoraco- and posterior lumbosacral regions (laminae VIII and IX). The ventral marginal nucleus consisted exclusively of SCT neurons but the major and minor marginal nuclei did not contain SCT neurons. In the cervical region most of SCT neurons were observed in the ventral horn, while the central cervical nucleus, which consists of SCT neurons in mammals, was not identified in the chicken.

Animals↗

PubMed2000

Hypothetical pathophysiology of acute encephalopathy and encephalitis related to influenza virus infection and hypothermia therapy.

BACKGROUND: To establish a treatment strategy for acute encephalopathy and encephalitis associated with influenza virus infection, the pathophysiology of the disease was investigated through manifestations and laboratory findings of patients. PATIENTS AND METHODS: A child with central nervous system (CNS) complications during the course of influenza virus infection was analyzed in view of immunologic abnormalities. In addition, four children with acute encephalopathy and encephalitis were enrolled in the hypothermia treatment for the purpose of stabilizing the cytokine storm in the CNS. RESULTS: The CNS symptoms preceded the systemic progression to the failure of multiple organs (MOF) and disseminated intravascular coagulopathy (DIC). The mild hypothermia suppressed the brain edema on computed tomography (CT) scanning and protected the brain from the subsequent irreversible neural cell damage. CONCLUSION: The replicated viruses at the nasopharyngeal epithelium may disrupt the olfactory mucosa and gain access to the brain via the olfactory nerve system. The direct virus-glial cell interaction or viral stimulation of the glial cells induces the production and accumulation of the pro-inflammatory cytokines, especially tumor necrosis factor (TNF)-alpha, in the CNS. The cytokine storm results in neural cell damage as well as the apoptosis of astrocytes, due to the TNF-alpha-induced mitochondrial respiratory failure. The disruption of the blood-brain barrier progresses to the systemic cytokine storm, resulting in DIC and MOF. Mild hypothermia appears promising in stabilizing the immune activation and the brain edema to protect the brain from ongoing functional, apoptotic neural and glial damage and the systemic expansion of the cytokine storm.

Acute Disease↗

PubMed2000

Ultrastructural characteristics and lectin-binding properties of M cells in the follicle-associated epithelium of chicken caecal tonsils.

To clarify the nature of M cells, the detailed ultrastructural characteristics and lectin-binding properties of M cells were investigated in follicle-associated epithelium (FAE) of chicken caecal tonsils. M cells presented various outlines from columnar to dome shaped. Their polymorphism was dependent on the number of harboured intraepithelial migrating cells. The lighter and larger nuclei of M cells were situated at more apical levels in the epithelial lining compared with those of neighbouring microvillous epithelial cells. The microvilli, which were significantly shorter and thicker than those of adjacent microvillous epithelial cells, were sparsely distributed or completely absent on the apical surfaces of M cells. In general, the apical cytoplasm of M cells without microvilli protruded slightly into the intestinal lumen. Numerous small vesicles were often contained in the apical cytoplasm. The numerous small invaginations of the apical and lateral cell surfaces suggested active transportation of luminal substances. No canaliculi existed in the apical cytoplasm of M cells whereas they were often detected in the neighbouring microvillous epithelial cells. A noteworthy finding was the frequent detection of multivesicular bodies in the apical cytoplasm of M cells. These multivesicular bodies suggest some degradation of ingested luminal substances during transcytoplasmic transportation. WGA and 4 other lectins strongly reacted with all epithelial cells except for M cells, this negativity suggesting a means of detecting M cells in chicken caecal tonsils. Three lectins, DSL, ConA and Jacalin, reacted weakly with the glycocalyx on M cells. The positive reactivity might allow chicken M cells to be utilised for specific antigen delivery into the mucosal immune system in some parenteral vaccinations.

Animals↗

PubMed2000

Comparative study of the lamina cribrosa and the pial septa in the vertebrate optic nerve and their relationship to the myelinated axons.

The optic nerve contains the connective tissues, i.e. the lamina cribrosa and pial septa. This report presents a histological comparison of the lamina cribrosa and pial septa in the five classes (mammals, birds, reptiles, amphibians and teleosts) of vertebrates. Furthermore, the distribution of myelinated fibers was observed from the optic nerve through the retina in the same animals. The lamina cribrosa is found in mammals except for mice, and in birds. Structural complexity of the lamina was different in animals but generally dependent of the optic nerve thickness. The pial septa were present in the optic nerve proper of the mammals except for the mice, in birds and in a part of teleosts. Fasciculation of the optic nerve by the pial septa tended to be more prominent as the optic nerve become thicker. The optic nerve consisted of largely myelinated fibers in vertebrates. The retina contained some myelinated fibers in submammals but was thoroughly devoid of myelinated fibers in mammals. The borderline between myelinated and unmyelinated portions in the optic nerve of different species did not related to the lamina cribrosa. Amphibians had exceptionally only a few myelinated fibers in the optic nerve and no myelinated fibers in the retina.

Amphibians↗

PubMed2000

Predictors of coronary artery lesions after intravenous gamma-globulin treatment in Kawasaki disease.

OBJECTIVE: We evaluated the efficacy of intravenous gamma-globulin (IVGG) administration for children with Kawasaki disease to establish whether additional, more advanced therapy is needed in intractable cases. STUDY DESIGN: A total of 193 children with Kawasaki disease were studied retrospectively. Patients were admitted 3 to 7 days after the onset of the disease, and IVGG was administered. Laboratory measurements including white blood cell (WBC), neutrophil, and platelet counts and C-reactive protein (CRP) and albumin concentrations were determined before and 2 to 3 days after IVGG treatment. The progression of coronary artery lesions (CALs) was monitored by serial echocardiography until 30 days after treatment. RESULTS: Of 193 children, 24 (12.2 %) had CALs including transient dilatation. In contrast to the other measurements, the WBC count increased in 21 of 24 (87.5%) children with CALs after IVGG therapy. The patients with increased neutrophil count and CRP concentration after IVGG therapy also had CAL formation at a high rate (78.3% and 66.7%, respectively). Among children with normal coronary arteries, elevations of the WBC and neutrophil counts and CRP concentration were observed after IVGG therapy in only 3, 6, and 8 patients, respectively (specificity: 98.2%, 97.0%, and 95.3%, respectively). Furthermore, multiple logistic regression indicated that these variables were useful predictors of CALs in KD. CONCLUSION: Though the introduction of IVGG therapy has improved the prognosis of Kawasaki disease, approximately 10% of patients still develop CALs. The need for more aggressive therapy in IVGG-resistant cases can be recognized early by increases in the WBC and neutrophil counts and serum CRP concentration after IVGG administration.

Biomarkers↗

PubMed2000

Membrane enzyme systems responsible for the Ca(2+)-dependent phosphorylation of Ser(27), the independent phosphorylation of Tyr(10) and Tyr(7), and the dephosphorylation of these phosphorylated residues in the alpha-chain of H/K-ATPase.

H/K-ATPase preparations (the G1 membrane) from pig stomach contain both kinases and phosphatases and show reversible phosphorylation of Tyr(7), Tyr(10), and Ser(27) residues of the alpha-chain of H/K-ATPase. The Tyr-kinase is sensitive to genistein and quercetin and recognized by anti-c-Src antibody. The Ser-kinase is dependent on Ca(2)(+) (K(0.5) = 0.9 microM), sensitive to a PKC inhibitor, and recognized by antibodies against PKCalpha and PKCbetaII. The addition of 3-[(3-cholamidopropyl)dimethylammonio]-1-propane-sulfonic acid (CHAPS) caused a dramatic increase in the phosphorylation of added synthetic copolymer substrates and permitted the phosphorylation of maltose-binding proteins fused with the N-terminal domain of alpha-chains. The phosphotyrosine phosphatase was inhibited by vanadate. The phosphoserine phosphatase was inhibited by okadaic acid and by inhibitor-2. The presence of protein phosphatase-1 was immunologically detected. Column chromatographic separation of CHAPS-solubilized G1 membrane and others indicate the apparent molecular weight of the Src-kinase to be approximately 60 kDa, the PKCalpha and/or PKCbII to be approximately 80 kDa, the Tyr-phosphatase to be 200 kDa, and PP-1 to be approximately 35 kDa. These data show that these membrane-bound enzyme systems are in sufficiently close proximity to be responsible for reversible phosphorylation of Tyr(7), Tyr(10), and Ser(27) of the catalytic subunit of membrane H/K-ATPase in parietal cells, the physiological role of which is unknown.

Animals↗

PubMed2000

Polychlorinated naphthalenes in soil, sediment, and biota collected near a former chloralkali plant in coastal Georgia, USA.

Concentrations of total polychlorinated naphthalenes (PCNs) as high as 23 micrograms/g, dry wt, were found in sediments contaminated by the disposal of wastes from chlor-alkali processes. Concentrations of total PCNs in blue crab, fish and birds were 3- to 5-orders of magnitude less than that in sediments. The profile of PCN congeners in biota was predominated by tetra- or penta-chloronaphthalenes, while hepta- and octa-chloronaphthalenes were dominant in sediments. The 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents (TEQs) estimated for PCNs in sediments and biota were greater than those reported for PCBs, PCDDs or PCDFs. These results suggest that chlor-alkali process is a source of PCNs found in the environment.

Animals↗

PubMed1999

Characterization of liposomes carrying von Willebrand factor-binding domain of platelet glycoprotein Ibalpha: a potential substitute for platelet transfusion.

Platelet glycoprotein (GP) Ib/IX/V complex is a receptor for von Willebrand factor (vWf), which plays a crucial role in primary hemostasis by mediating platelet adhesion to injured blood vessels. We have expressed in CHO cells a fragment of GPIba that retained a vWf-binding function. The recombinant fragment (rGPIba) was incorporated into liposomes and evaluated their functions in vitro. rGPIba on the liposome surface was detectable by flow cytometric analysis. Addition of vWf and ristocetin caused specific agglutination of rGPIbalpha-liposomes, as evaluated by an aggregometer or a fluorescent microscopy. When ristocetin was added to platelet-rich plasma (PRP) pre-mixed with rhodamine-labeled rGPIbalpha-liposomes, platelets aggregated and rhodamine-fluorescence was strongly positive in the platelet thrombi, suggesting that heterologous aggregation (attachment of liposomes to platelets) occurred. Platelet aggregation in PRP at low platelet concentration (20-80 x 10(6)/ml) was enhanced by rGPIbalpha-liposomes in a dose-dependent manner. Thus, rGPIbalpha-liposomes may accumulate on vWf-exposed subendothelial tissues and enhance platelet function in vivo, supporting hemostasis in thrombocytopenic individuals.

Animals↗

PubMed1999

Prostaglandin E1 transported into cells blocks the apoptotic signals induced by nerve growth factor deprivation.

Neuronal apoptosis in rat pheochromocytoma PC12 cells, which was confirmed by TUNEL (terminal transferase-mediated dUTP-biotin nick end-labeling) staining and detection of chromatin condensation, appeared within 8 h after nerve growth factor (NGF) deprivation. Prostaglandin (PG) E1 (10(-7)-10(6) M) reduced the incidence of apoptotic cell death in PC12 cells. The genes encoding PG transporter specific to prostaglandins such as PGE2 or PGF2alpha were expressed in the cell lines as shown by RT-PCR. Bromcresol green, an inhibitor of PG transporter, reversed the antiapoptotic effect of PGE1. Moreover, treatment of PC12 cells with an antisense oligonucleotide corresponding to PG transporter cDNA also blocked the inhibitory effects of PGE1 on apoptotic cell death. In addition, PGE1 counteracted the increased activities of stress-activated protein kinase/cJun N-terminal kinase within 1-2 h after NGF deprivation in PC12 cells. These results indicated that the antiapoptotic effect of PGE1 in NGF-deprived PC12 cells was achieved by inhibitory signals following uptake into neurons through the PG transporter.

Alprostadil↗

PubMed1999

The influence of methicillin-resistant Staphylococcus aureus (MRSA) carriers in a nursery and transmission of MRSA to their households.

We examined two persistent MRSA-carrier nurses in a maternity hospital to elucidate the transmission of methicillin-resistant Staphylococcus aureus (MRSA) from healthcare providers to newborn infants and to the nurses' own families. Genotyping of the MRSA strains was performed by analyzing genomic DNA restriction length polymorphisms from pulsed-field gel electrophoresis (PFGE-RFLPs). The children of these nurses were carrying genotypically identical MRSA strains as their mother. Both MRSA carrier families remained asymptomatic over a two-year follow-up period. Eradication of nasal MRSA carriage from the two nurses resulted in declining MRSA carriage rates among infants in the nursery. Healthcare providers may become transient or persistent MRSA carriers whilst working in hospitals in which MRSA is endemic. They may then become a source of infection for patients as well as their own families. We recommend that healthcare providers should be examined for MRSA if an MRSA epidemic occurs in a hospital. The families of any such carriers should also be examined for MRSA.

Adult↗

PubMed1999

Direct evidence for in vivo reversible tyrosine phosphorylation of the N-terminal domain of the H/K-ATPase alpha-subunit in mammalian stomach cells.

In vivo reversible phosphorylation of Tyr-7 and Tyr-10 of the pig stomach H/K-ATPase alpha-chain was initially demonstrated in mammals, rat, rabbit, and pig, in the presence of vanadate + H(2)O(2). In vitro phosphorylation has also been unequivocally demonstrated via the use of protease inhibitors during membrane H/K-ATPase preparation. An amphoretic detergent permitted each intrinsic kinase to phosphorylate each fusion protein containing the requisite Tyr residues, along with a reduction in alpha-chain phosphorylation. These and other data suggest that some important enzyme systems are present in the apical membrane and that they are in sufficient proximity to participate in the reversible phosphorylation of the amino terminal soluble domain of the alpha-chain with an unknown physiological function in the membrane embedded H/K-ATPase.

Animals↗

PubMed1999

[Computed tomography with normal chest radiography in childhood tuberculosis].

During the recent 2 years we experienced 5 children (2 months-5 years old) with lung tuberculosis, all of whom had positive tuberculin skin-tests, and were in close contact with their family members who had active tuberculosis. However, no abnormal findings on chest X-ray films were pointed out by 2 independent roentogenologists, and no increased levels of inflammatory markers including WBC numbers, CRP, and ESR were detected in all but one child. Moreover, mycobacterial examination of sputa and/or gastric aspirates by microscope, culture technique, and PCR amplification revealed no causative bacilli in 4 children. To clarify whether these children were affected by Mycobacterium tuberculosis, chest CT scan was applied. Surprisingly, all 5 children were revealed to have abnormal changes including primary complexes in the lung field. Taken together, it is important to pursuit the apparent lung tuberculosis in children with a positive family history and positive tuberculin skin-test.

Child↗