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  • 1
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Group IB secretory phospholipase A2 (sPLA2-IB) mediates cell proliferation, cell migration, hormone release and eicosanoid production via its receptor in peripheral tissues. In the CNS, high-affinity binding sites of sPLA2-IB have been documented. However, it remains obscure whether sPLA2-IB causes biologic or pathologic response in the CNS. To this end, we examined effects of sPLA2-IB on neuronal survival in primary cultures of rat cortical neurons. sPLA2-IB induced neuronal cell death in a concentration-dependent manner. This death was a delayed response requiring a latent time for 6 h; sPLA2-IB-induced neuronal cell death was accompanied with apoptotic blebbing, condensed chromatin, and fragmented DNA, exhibiting apoptotic features. Before cell death, sPLA2-IB liberated arachidonic acid (AA) and generated prostaglandin D2 (PGD2) from neurons. PGD2 and its metabolite, Δ12-PGJ2, exhibited neurotoxicity. Inhibitors of sPLA2 and cyclooxygenase-2 (COX-2) significantly suppressed not only AA release, but also PGD2 generation. These inhibitors significantly prevented neurons from sPLA2-IB-induced neuronal cell death. In conclusion, we demonstrate a novel biological response, apoptosis, of sPLA2-IB in the CNS. Furthermore, the present study suggests that PGD2 metabolites, especially Δ12-PGJ2, might mediate sPLA2-IB-induced apoptosis.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Mammalian group IIA secretory phospholipase A2 (sPLA2-IIA) generates prostaglandin D2 (PGD2) and triggers apoptosis in cortical neurons. However, mechanisms of PGD2 generation and apoptosis have not yet been established. Therefore, we examined how second messengers are involved in the sPLA2-IIA-induced neuronal apoptosis in primary cultures of rat cortical neurons. sPLA2-IIA potentiated a marked influx of Ca2+ into neurons before apoptosis. A calcium chelator and a blocker of the L-type voltage-sensitive Ca2+ channel (L-VSCC) prevented neurons from sPLA2-IIA-induced neuronal cell death in a concentration-dependent manner. Furthermore, the L-VSCC blocker ameliorated sPLA2-IIA-induced morphologic alterations and apoptotic features such as condensed chromatin and fragmented DNA. Other blockers of VSCCs such as N type and P/Q types did not affect the neurotoxicity of sPLA2-IIA. Blockers of L-VSCC significantly suppressed sPLA2-IIA-enhanced Ca2+ influx into neurons. Moreover, reactive oxygen species (ROS) were generated prior to apoptosis. Radical scavengers reduced not only ROS generation, but also the sPLA2-IIA-induced Ca2+ influx and apoptosis. In conclusion, we demonstrated that sPLA2-IIA potentiates the influx of Ca2+ into neurons via L-VSCC. Furthermore, the present study suggested that eicosanoids and ROS generated during arachidonic acid oxidative metabolism are involved in sPLA2-IIA-induced apoptosis in cooperation with Ca2+.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-1106
    Keywords: Inspiratory neurons ; Hypoglossal motoneuron ; Phrenic motoneuron ; Dual-projection neuron ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Localization and projection to the phrenic (PH) nucleus were studied in a sample of premotor neurons that directly projected to hypoglossal motoneurons (XII Mns) and showed respiratory-related patterns of activity. The experiments were carried out in cats, under pentobarbital anesthesia. In the first part of the study, the retrograde double-labeling technique was used to reveal the existence of neurons projecting to both the XII and the PH nuclei. Injection of a fluorescent dye (fast blue, FB) into the XII nucleus and another (nuclear yellow, NY) into the PH nucleus retrogradely labeled, with either FB or NY, medullary reticular neurons mainly in the regions ventrolateral to the nucleus of the tractus solitarius (vl-NTS), ventrolateral to the hypoglossal nucleus (vl-XII), and dorsomedial to the nucleus ambiguus (dm-AMB) bilaterally. In addition, some neurons in these regions were labeled with both FB and NY. In the second part of the study, unitary activity was recorded extracellularly from medullary respiratory neurons. In the regions vl-NTS, vl-XII, and dm-AMB, inspiratory neurons were found which antidromically responded to stimulation of the XII nucleus. Some of them also responded antidromically to stimulation of the PH nucleus. Averaging of rectified and integrated XII and PH nerve discharges by spontaneous spikes of single inspiratory neurons in the vl-NTS and dm-AMB regions revealed a facilitation in either XII nerve discharge or both XII and PH nerve discharges after a short latency of monosynaptic range. It is concluded that in the vl-NTS and dm-AMB regions there are inspiratory neurons that are excitatory premotor neurons projecting to XII Mns showing the respiratory-related activity. Some of them have excitatory synaptic connections to XII and PH Mns via bifurcating axons.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1435-5604
    Keywords: Key words: fibroblast growth factor receptor (FGFR) ; cartilage ; condyle ; tibia ; immunohistochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract: The fibroblast growth factor receptors (FGFRs), members of the tyrosine-kinase receptor family, are known to play a crucial role in the growth and development of cartilaginous tissues. The mandibular condylar cartilage has been suggested to have a characteristic growth pattern compared with the tibial growth plate cartilage, e.g., cell alignment, mode of proliferation and differentiation, and response to humoral and mechanical factors. To examine the mRNA expression and localization of fibroblast growth factor receptor (FGFR)-1, -2, and -3 in the condylar and tibial growth plate cartilages, reversed transcribed polymerase chain reaction (RT-PCR) assay and immunohistochemistry were carried out using growing rats. The enzymatically isolated rat condylar and tibial chondrocytes expressed mRNA of aggrecan and type II collagen, which are together known as the major cartilaginous extracellular matrices. Both types of cells expressed mRNA of FGFR-1, -2, and -3 by RT-PCR. In the neonatal rat, immunolocalization of FGFR-1, -2, and -3 was found in the middle of the condylar cartilage, mainly in the hypertrophic zone of the tibial cartilage. At 3 weeks old, the three FGFRs were broadly observed in both cartilages. At 8 weeks old, localization of FGFR-3 was absent in the hypertrophic cell layer of the condyle, whereas it was still broadly observed in the tibial growth plate cartilage. In the same stage, FGFR-1 and FGFR-2 showed similar localization in both cartilages to that at 3 weeks of age. All these observations suggest that FGFRs play an important role in the differential growth pattern of the condylar cartilage.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1573-2576
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Among arachidonic acid metabolites, leukotriene B4 (LTB4) plays an important role in inflammation, such as in the activation, adhesion, chemotaxis, and invasion of leukocytes. In this paper, we examined the effect of LTB4 on endothelial cell injury induced by polymorphonuclear leukocytes (PMNLs).51Crrelease, a marker of cellular injury, was elicited from prelabeled endothelial cells when the cells were cocultured with PMNLs activated by phorbol ester (TPA, 12-0-tetradecanoyl-phorbol-13-acetate). Under this condition, pretreatment of PMNLs with LTB4 enhanced their injury in a dose-dependent manner (0.2–2 μM). However, LTB4 alone at any dose could not induce any cellular injury. We also determined the amount of active oxygen species produced by PMNLs in response to TPA. The intensity of luminoldependent chemiluminescence, a marker of active oxygen production, in PMNLs was also increased by pretreatment with 1 μM LTB4. These data suggest that LTB4 enhances endothelial cell injury by the priming effect on active oxygen production in activated PMNLs.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1435-232X
    Keywords: HMC syndrome ; de novo translocation ; 1q/7p ; highresolution banding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary High-resolution band analysis was performed in order to precisely determine the breakpoints of ade novo chromosome translocation, t(1;7), which is associated with clinical signs of HMC syndrome (McKusick's #239800). The breakpoints were found to be at 1q31.2 and 7p15.1–p15.3, respectively. The finding of the translocation in this case might not be coincidental, but rather suggestive of the gene locus responsible for the development of HMC syndrome at either site of the breakpoints.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 27 (1993), S. 399-402 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The effect of heat treatment temperature on bending properties and transformation temperatures of a Ni-Ti alloy wire, 1.0 mm in diameter, was investigated so that superelasticity could be used in orthodontic appliances needing shape memory processes. The heat treatment process was at 713 K for 1.8 ks and between 673 K and 813 K for 1.8 ks. A three-point bending test and differential scanning calorimetry were performed. The transformation temperatures of the wires were lowered with increasing heat treatment temperature. The reverse transformation finishing temperature was below the body temperature with the treatment above 753 K. Residual deflection of the Ni-Ti wire after bending was small with the secondry heat treatment above 733 K. The load in the unloading process was less changeable and increased with the treatment temperature between 733-813 K. Secondary heat treatment in this range was suitable for using superelasticity in expansion arch appliances. © 1993 John Wiley & Sons, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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