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1.
J Biol Chem ; 299(8): 105057, 2023 08.
Artículo en Inglés | MEDLINE | ID: mdl-37468106

RESUMEN

In wild-type phototrophic organisms, carotenoids (Crts) are primarily packed into specific pigment-protein complexes along with (Bacterio)chlorophylls and play important roles in the photosynthesis. Diphenylamine (DPA) inhibits carotenogenesis but not phototrophic growth of anoxygenic phototrophs and eliminates virtually all Crts from photocomplexes. To investigate the effect of Crts on assembly of the reaction center-light-harvesting (RC-LH) complex from the filamentous anoxygenic phototroph Roseiflexus (Rfl.) castenholzii, we generated carotenoidless (Crt-less) RC-LH complexes by growing cells in the presence of DPA. Here, we present cryo-EM structures of the Rfl. castenholzii native and Crt-less RC-LH complexes with resolutions of 2.86 Å and 2.85 Å, respectively. From the high-quality map obtained, several important but previously unresolved details in the Rfl. castenholzii RC-LH structure were determined unambiguously including the assignment and likely function of three small polypeptides, and the content and spatial arrangement of Crts with bacteriochlorophyll molecules. The overall structures of Crt-containing and Crt-less complexes are similar. However, structural comparisons showed that only five Crts remain in complexes from DPA-treated cells and that the subunit X (TMx) flanked on the N-terminal helix of the Cyt-subunit is missing. Based on these results, the function of Crts in the assembly of the Rfl. castenholzii RC-LH complex and the molecular mechanism of quinone exchange is discussed. These structural details provide a fresh look at the photosynthetic apparatus of an evolutionary ancient phototroph as well as new insights into the importance of Crts for proper assembly and functioning of the RC-LH complex.


Asunto(s)
Proteínas Bacterianas , Chloroflexi , Fotosíntesis , Proteínas Bacterianas/metabolismo , Carotenoides/metabolismo , Chloroflexi/metabolismo , Complejos de Proteína Captadores de Luz/química
2.
Diabetes Metab Res Rev ; 40(1): e3706, 2024 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-37545385

RESUMEN

OBJECTIVE: To explore the difference in temperature recovery following cold stimulation between participants with and without diabetes mellitus (DM). MATERIALS AND METHODS: The participants without (control group; n = 25) and with (DM group; n = 26) DM were subjected to local cold stimulation (10º C for 90 s). The thermal images of their hands were continuously captured using a thermal camera within 7 min following cold stimulation, and the highest temperature of each fingertip was calculated. According to the temperature values at different timepoints, the temperature recovery curves were drawn, and the baseline temperature (T-base), initial temperature after cooling (T0), temperature decline amplitude (T-range), and area under the temperature recovery curve > T0 (S) were calculated. Finally, symmetry differences between the two groups were analysed. RESULTS: No statistical differences in the T-base, T0, and T-range were observed between the DM and control groups. After drawing the rewarming curve according to the temperature of the fingertips of the patients following cold stimulation, the S in the DM group was significantly lower than that in the control group (p < 0.05). Furthermore, the asymmetry of the base temperature of the hand was observed in the DM group. CONCLUSIONS: Following cold stimulation, the patients with DM exhibited a different rewarming pattern than those without DM. Thus, cold stimulation tests under infrared thermography may contribute to the early screening of diabetic peripheral neuropathy in future.


Asunto(s)
Diabetes Mellitus , Termografía , Humanos , Temperatura , Termografía/métodos , Frío , Recalentamiento , Temperatura Cutánea
3.
J Integr Plant Biol ; 2024 Feb 27.
Artículo en Inglés | MEDLINE | ID: mdl-38411333

RESUMEN

Halorhodospira (Hlr.) halochloris is a triply extremophilic phototrophic purple sulfur bacterium, as it is thermophilic, alkaliphilic, and extremely halophilic. The light-harvesting-reaction center (LH1-RC) core complex of this bacterium displays an LH1-Qy transition at 1,016 nm, which is the lowest-energy wavelength absorption among all known phototrophs. Here we report the cryo-EM structure of the LH1-RC at 2.42 Å resolution. The LH1 complex forms a tricyclic ring structure composed of 16 αßγ-polypeptides and one αß-heterodimer around the RC. From the cryo-EM density map, two previously unrecognized integral membrane proteins, referred to as protein G and protein Q, were identified. Both of these proteins are single transmembrane-spanning helices located between the LH1 ring and the RC L-subunit and are absent from the LH1-RC complexes of all other purple bacteria of which the structures have been determined so far. Besides bacteriochlorophyll b molecules (B1020) located on the periplasmic side of the Hlr. halochloris membrane, there are also two arrays of bacteriochlorophyll b molecules (B800 and B820) located on the cytoplasmic side. Only a single copy of a carotenoid (lycopene) was resolved in the Hlr. halochloris LH1-α3ß3 and this was positioned within the complex. The potential quinone channel should be the space between the LH1-α3ß3 that accommodates the single lycopene but does not contain a γ-polypeptide, B800 and B820. Our results provide a structural explanation for the unusual Qy red shift and carotenoid absorption in the Hlr. halochloris spectrum and reveal new insights into photosynthetic mechanisms employed by a species that thrives under the harshest conditions of any phototrophic microorganism known.

4.
Mol Pain ; 14: 1744806918767560, 2018.
Artículo en Inglés | MEDLINE | ID: mdl-29607715

RESUMEN

Treating bone cancer pain continues to be a clinical challenge and underlying mechanisms of bone cancer pain remain elusive. Here, we reported that sonic hedgehog signaling plays a critical role in the development of bone cancer pain. Tibia bone cavity tumor cell implantation produces bone cancer-related mechanical allodynia, thermal hyperalgesia, and spontaneous and movement-evoked pain behaviors. Production and persistence of these pain behaviors are well correlated with tumor cell implantation-induced up-regulation and activation of sonic hedgehog signaling in primary sensory neurons and spinal cord. Spinal administration of sonic hedgehog signaling inhibitor cyclopamine prevents and reverses the induction and persistence of bone cancer pain without affecting normal pain sensitivity. Inhibiting sonic hedgehog signaling activation with cyclopamine, in vivo or in vitro, greatly suppresses tumor cell implantation-induced increase of intracellular Ca2+ and hyperexcitability of the sensory neurons and also the activation of GluN2B receptor and the subsequent Ca2+-dependent signals CaMKII and CREB in dorsal root ganglion and the spinal cord. These findings show a critical mechanism underlying the pathogenesis of bone cancer pain and suggest that targeting sonic hedgehog signaling may be an effective approach for treating bone cancer pain.


Asunto(s)
Neoplasias Óseas/complicaciones , Dolor en Cáncer/etiología , Dolor en Cáncer/patología , Proteínas Hedgehog/metabolismo , Células Receptoras Sensoriales/metabolismo , Células Receptoras Sensoriales/patología , Transducción de Señal , Animales , Calcio/metabolismo , Dolor en Cáncer/metabolismo , Línea Celular Tumoral , Femenino , Ganglios Espinales/metabolismo , Ganglios Espinales/patología , Espacio Intracelular/metabolismo , Trasplante de Neoplasias , Nocicepción , Ratas Sprague-Dawley , Médula Espinal/patología , Regulación hacia Arriba
5.
Phys Rev Lett ; 120(12): 124101, 2018 Mar 23.
Artículo en Inglés | MEDLINE | ID: mdl-29694077

RESUMEN

We uncover a remarkable quantum scattering phenomenon in two-dimensional Dirac material systems where the manifestations of both classically integrable and chaotic dynamics emerge simultaneously and are electrically controllable. The distinct relativistic quantum fingerprints associated with different electron spin states are due to a physical mechanism analogous to a chiroptical effect in the presence of degeneracy breaking. The phenomenon mimics a chimera state in classical complex dynamical systems but here in a relativistic quantum setting-henceforth the term "Dirac quantum chimera," associated with which are physical phenomena with potentially significant applications such as enhancement of spin polarization, unusual coexisting quasibound states for distinct spin configurations, and spin selective caustics. Experimental observations of these phenomena are possible through, e.g., optical realizations of ballistic Dirac fermion systems.

6.
Parasitol Res ; 115(7): 2573-9, 2016 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-26987644

RESUMEN

Gasterophilus spp. (Diptera: Gasterophilidae) has a worldwide distribution; however, no complete mitochondrial (mt) genome data is available for Diptera which has greatly impeded population genetics, phylogenetics, and systematics studies in Gasterophilidae. Mt genome is known to provide genetic markers for investigations in these areas, but complete mt genomic datasets have been lacking for many Gasterophilidae species. Herein, we present the complete mt genome of the third-stage larvae (L3) of Gasterophilus intestinalis from the stomach wall of naturally infected horses in Heilongjiang province (HLJ) and Xinjiang Uygur Autonomous Region (XJ), China. The complete mt genome of G. intestinalis was 15,687 bp (HLJ) and 15,660 bp (XJ) in length and consists of 37 genes, including 13 genes for proteins, 22 genes for tRNA, and 2 genes for rRNA. The gene arrangement is the same as those of Oestroidae species. Phylogenetic analyses using concatenated amino acid sequences of 12 protein-coding genes by Bayesian inference (BI) and maximum likelihood (ML), suggested that the families Gasterophilidae and Oestroidae were more closely related than to Tachinidae. The mt genome of G. intestinalis represents the first mt genome of any member of the family Gasterophilidae. These data provide novel mtDNA markers for studying the molecular epidemiology and population genetics of the G. intestinalis and its congeners.


Asunto(s)
ADN Mitocondrial/genética , Dípteros/clasificación , Dípteros/genética , Genoma Mitocondrial/genética , Caballos/parasitología , Estómago/parasitología , Secuencia de Aminoácidos , Animales , China , Orden Génico , Marcadores Genéticos , Larva/genética , Parásitos/clasificación , Parásitos/genética , Parásitos/crecimiento & desarrollo , Filogenia , ARN Ribosómico/genética , ARN de Transferencia/genética , Estómago/patología
7.
J Phys Chem Lett ; 15(13): 3619-3626, 2024 Apr 04.
Artículo en Inglés | MEDLINE | ID: mdl-38530255

RESUMEN

The light-harvesting (LH) and reaction center (RC) core complex of purple bacterium Roseiflexus castenholzii, B880-B800-RC, are different from those of the typical photosynthetic unit, (B850-B800)x-B880-RC. To investigate the excitation flowing dynamics in this unique complex, two-dimensional electronic spectroscopy is employed. The obtained time constants for the exciton relaxation in B880, exciton relaxation in B800, B800 → B880 energy transfer (EET), and B880 → closed RC EET are 43 fs, 177 fs, 1.9 ps, and 205 ps, respectively. These time constants result in an overall EET efficiency similar to that of the typical photosynthetic unit. Analysis of the oscillatory signals reveals that while several vibronic coherences are involved in the exciton relaxation process, only one prominent vibronic coherence, with a frequency of 27 cm-1 and coupled to the B880 electronic transition, may contribute to the B800 → B880 EET process.

8.
Biochim Biophys Acta Bioenerg ; 1865(3): 149050, 2024 Aug 01.
Artículo en Inglés | MEDLINE | ID: mdl-38806091

RESUMEN

Purple phototrophic bacteria possess light-harvesting 1 and reaction center (LH1-RC) core complexes that play a key role in converting solar energy to chemical energy. High-resolution structures of LH1-RC and RC complexes have been intensively studied and have yielded critical insight into the architecture and interactions of their proteins, pigments, and cofactors. Nevertheless, a detailed picture of the structure and assembly of LH1-only complexes is lacking due to the intimate association between LH1 and the RC. To study the intrinsic properties and structure of an LH1-only complex, a genetic system was constructed to express the Thermochromatium (Tch.) tepidum LH1 complex heterologously in a modified Rhodospirillum rubrum mutant strain. The heterologously expressed Tch. tepidum LH1 complex was isolated in a pure form free of the RC and exhibited the characteristic absorption properties of Tch. tepidum. Cryo-EM structures of the LH1-only complexes revealed a closed circular ring consisting of either 14 or 15 αß-subunits, making it the smallest completely closed LH1 complex discovered thus far. Surprisingly, the Tch. tepidum LH1-only complex displayed even higher thermostability than that of the native LH1-RC complex. These results reveal previously unsuspected plasticity of the LH1 complex, provide new insights into the structure and assembly of the LH1-RC complex, and show how molecular genetics can be exploited to study membrane proteins from phototrophic organisms whose genetic manipulation is not yet possible.


Asunto(s)
Chromatiaceae , Complejos de Proteína Captadores de Luz , Complejos de Proteína Captadores de Luz/metabolismo , Complejos de Proteína Captadores de Luz/química , Complejos de Proteína Captadores de Luz/genética , Chromatiaceae/metabolismo , Chromatiaceae/genética , Proteínas Bacterianas/química , Proteínas Bacterianas/metabolismo , Proteínas Bacterianas/genética , Rhodospirillum rubrum/genética , Rhodospirillum rubrum/metabolismo
9.
J Cardiovasc Pharmacol ; 59(4): 352-62, 2012 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-22286127

RESUMEN

We have previously demonstrated that dl-3n-butylphthalide (NBP) has a potential angiogenic activity. In this study, we investigated the angiogenic effect of NBP and the molecular mechanisms underlying NBP-mediated angiogenesis. Zebrafish embryos and human umbilical vein endothelial cells were treated with various doses of NBP and several signaling pathway inhibitors. NBP induced ectopic subintestinal vessel production in zebrafish embryos and induced invasion, migration, and endothelial cell tube formation of human umbilical vein endothelial cells in a dose-dependent manner. These NBP-induced angiogenic effects were partially suppressed by SU5402, a fibroblast growth factor receptor 1 inhibitor; U0126, an extracellular signal-regulated kinase 1/2 (ERK1/2) inhibitor; LY294002, a phosphatidylinositol 3-kinase inhibitor; 1L6-hydroxymethyl-chiro-inositol-2-(R)-2-O-methyl-3-O-octadecyl-sn-glycerocarbonate, an Akt inhibitor; cavtratin, an endothelial nitric oxide synthase (eNOS) inhibitor and completely inhibited by a combination of U0126 and LY294002. NBP enhanced phosphorylation of ERK1/2 and fibroblast growth factor receptor 2 expression, which were inhibited by U0126. NBP increased the phosphorylation of Akt and eNOS at serine 1177, which was blocked by LY294002. NBP-stimulated nitric oxide production, which was reduced by LY294002. Our data demonstrated that (1) NBP promoted angiogenesis and (2) the angiogenic effects of NBP were mediated by the ERK1/2 and phosphatidylinositol 3-kinase/Akt-eNOS signaling pathways. Our findings suggest that NBP could be a novel agent for therapeutic angiogenesis in ischemic diseases.


Asunto(s)
Benzofuranos/farmacología , Neovascularización Fisiológica/efectos de los fármacos , Fármacos Neuroprotectores/farmacología , Transducción de Señal/efectos de los fármacos , Animales , Benzofuranos/administración & dosificación , Relación Dosis-Respuesta a Droga , Células Endoteliales de la Vena Umbilical Humana , Humanos , Proteína Quinasa 1 Activada por Mitógenos/metabolismo , Proteína Quinasa 3 Activada por Mitógenos/metabolismo , Fármacos Neuroprotectores/administración & dosificación , Óxido Nítrico Sintasa de Tipo III/metabolismo , Fosfatidilinositol 3-Quinasas/metabolismo , Fosforilación , Proteínas Proto-Oncogénicas c-akt/metabolismo , Pez Cebra/embriología
10.
Mar Drugs ; 10(6): 1307-1320, 2012 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-22822374

RESUMEN

Cyclotripeptide X-13 is a core of novel marine compound xyloallenoide A isolated from mangrove fungus Xylaria sp. (no. 2508). We found that X-13 dose-dependently induced angiogenesis in zebrafish embryos and in human endothelial cells, which was accompanied by increased phosphorylation of eNOS and Akt and NO release. Inhibition of PI3K/Akt/eNOS by LY294002 or L-NAME suppressed X-13-induced angiogenesis. The present work demonstrates that X-13 promotes angiogenesis via PI3K/Akt/eNOS pathways.


Asunto(s)
Inductores de la Angiogénesis/farmacología , Organismos Acuáticos/química , Neovascularización Fisiológica/efectos de los fármacos , Óxido Nítrico Sintasa de Tipo III/metabolismo , Fosfatidilinositol 3-Quinasas/metabolismo , Proteínas Proto-Oncogénicas c-akt/metabolismo , Transducción de Señal/efectos de los fármacos , Inductores de la Angiogénesis/síntesis química , Inductores de la Angiogénesis/química , Inductores de la Angiogénesis/aislamiento & purificación , Animales , Productos Biológicos/síntesis química , Productos Biológicos/química , Productos Biológicos/aislamiento & purificación , Productos Biológicos/farmacología , Línea Celular , Cromonas/farmacología , Células Endoteliales/efectos de los fármacos , Células Endoteliales/metabolismo , Hongos/química , Células Endoteliales de la Vena Umbilical Humana , Humanos , Morfolinas/farmacología , NG-Nitroarginina Metil Éster/farmacología , Óxido Nítrico/metabolismo , Óxido Nítrico Sintasa de Tipo III/antagonistas & inhibidores , Inhibidores de las Quinasa Fosfoinosítidos-3 , Fosforilación/efectos de los fármacos , Proteínas Proto-Oncogénicas c-akt/antagonistas & inhibidores , Pez Cebra/metabolismo
11.
Eur J Pharmacol ; 584(1): 159-65, 2008 Apr 14.
Artículo en Inglés | MEDLINE | ID: mdl-18328478

RESUMEN

The pathogenesis of acute lung injury/acute respiratory distress syndrome (ARDS) is complex and involves multiple signal transduction processes. It is believed that p38MAPK (mitogen-activated protein kinase) is one of the most kinases in inflammatory signaling. At present study, we demonstrated the role of p38MAPK in lipopolysaccharide (LPS)-induced acute lung injury with pharmacologic p38MAPK inhibition by SB203580. SB203580, p38MAPK specific inhibitor, was injected (10 mg/kg, i.v.) 30 min before LPS administration (5 mg/kg, i.v.). The hematoxylin-eosin staining of lung tissues showed that p38MAPK inhibition significantly attenuated the pulmonary inflammatory responses induced by LPS. Moreover, SB203580 can also inhibit the inflammatory cytokine release, and reduce the mortality rate of LPS-induced acute lung injury. Further, western blot analysis that showed SB203580 administration can inhibit the activation of NF-kappaB, which was associated with the inhibition of IkappaBalpha degradation in cytoplasm. These data suggest that p38MAPK signaling may be involved in the activation of NF-kappaB, and activation of p38MAPK signaling may be one of the mechanisms of acute lung injury.


Asunto(s)
Imidazoles/farmacología , Pulmón/efectos de los fármacos , FN-kappa B/metabolismo , Inhibidores de Proteínas Quinasas/farmacología , Piridinas/farmacología , Síndrome de Dificultad Respiratoria/tratamiento farmacológico , Transducción de Señal/efectos de los fármacos , Proteínas Quinasas p38 Activadas por Mitógenos/antagonistas & inhibidores , Animales , Líquido del Lavado Bronquioalveolar/química , Citocinas/metabolismo , Modelos Animales de Enfermedad , Activación Enzimática , Proteínas I-kappa B/metabolismo , Imidazoles/administración & dosificación , Mediadores de Inflamación/metabolismo , Inyecciones Intravenosas , Interleucina-6/metabolismo , Lipopolisacáridos , Pulmón/enzimología , Pulmón/metabolismo , Pulmón/patología , Masculino , Inhibidor NF-kappaB alfa , Tamaño de los Órganos , Inhibidores de Proteínas Quinasas/administración & dosificación , Piridinas/administración & dosificación , Ratas , Ratas Sprague-Dawley , Síndrome de Dificultad Respiratoria/inducido químicamente , Síndrome de Dificultad Respiratoria/metabolismo , Síndrome de Dificultad Respiratoria/patología , Factores de Tiempo , Factor de Necrosis Tumoral alfa/metabolismo , Proteínas Quinasas p38 Activadas por Mitógenos/metabolismo
12.
Pharmacology ; 81(1): 32-40, 2008.
Artículo en Inglés | MEDLINE | ID: mdl-17785997

RESUMEN

BACKGROUND AND OBJECTIVES: Lidocaine has been reported to attenuate the inflammatory response in addition to its anesthetic activity, but the mechanisms are poorly understood. The objective of this study is to determine if lidocaine prior to endotoxemia diminishes pulmonary dysfunction by blocking the NF-kappaB activation. METHODS: Rats were assigned to: (1) control (0.9% sodium chloride); (2) lipopolysaccharides (LPS); (3) LPS + lidocaine 1 mg/kg; (4) LPS + lidocaine 2 mg/kg, and (5) LPS + lidocaine 4 mg/kg. The LPS and LPS + lidocaine 4 mg/kg groups were subjected to 1-, 3-, 6- and 12-hour time points. To investigate the activation of NF-kappaB, the expression of NF-kappaB in the nuclear and I kappaB alpha in the cytosol extracts were analyzed by Western blot. The concentration of TNF-alpha and IL-6 in serum was detected by ELISA. The pathologic changes of the lung were observed using HE staining. RESULTS: After i.p. injection of LPS, the expression of NF-kappaB in the nuclear extracts was significantly increased and I kappaB alpha in the cytosol extracts was markedly decreased. The concentration of TNF-alpha and IL-6 in serum was increased. Pathological examination showed that the normal structure of the lung was destroyed badly. However, lidocaine reversed the above results. CONCLUSION: Lidocaine attenuates LPS-induced lung injury via mechanisms involving inhibiting NF-kappaB activation and cytokine release, which implies that lidocaine may be a potential anti-inflammatory agent in endotoxemia.


Asunto(s)
Antiinflamatorios/uso terapéutico , Lidocaína/uso terapéutico , FN-kappa B/antagonistas & inhibidores , Síndrome de Dificultad Respiratoria/prevención & control , Animales , Antiinflamatorios/administración & dosificación , Antiinflamatorios/farmacología , Western Blotting , Citocinas/sangre , Modelos Animales de Enfermedad , Ensayo de Inmunoadsorción Enzimática , Lidocaína/administración & dosificación , Lidocaína/farmacología , Lipopolisacáridos , Pulmón/efectos de los fármacos , Pulmón/inmunología , Pulmón/patología , Masculino , FN-kappa B/biosíntesis , Ratas , Ratas Sprague-Dawley , Síndrome de Dificultad Respiratoria/inducido químicamente , Síndrome de Dificultad Respiratoria/inmunología , Síndrome de Dificultad Respiratoria/patología
13.
Artículo en Inglés | MEDLINE | ID: mdl-26710301

RESUMEN

Horse gastrointestinal myiasis caused by larvae of Gasterophilus spp. has a worldwide distribution. However, little information is available on the genetic variation of Gasterophilus spp. at the molecular level. In the present study, sequence variation was examined in three mitochondrial (mt) genes, namely mt cytochrome c oxidase subunit 1 (cox1), NADH dehydrogenase subunits 5 (nad5) and large subunit ribosomal RNA (rrnL), among G. intestinalis isolates originating from Heilongjiang Provience and Xinjiang Uygur Autonomous Region, China. The complete cox1, nad5, and rrnL gene sequences were amplified by PCR separately from adult G. intestinalis individuals and the amplicons were sequenced from both directions. The size of the sequences of cox1, nad5, and rrnL genes was 1539 bp, 1717 bp, and 1321 bp, respectively. The A + T contents of the sequences were 62.7-63.9% (cox1), 70-70.7% (nad5), and 74.5-74.9% (rrnL). The intra-specific sequence variations within G. intestinalis were 0.1-3.1% for cox1, 0.4-3.4% for nad5, and 0.1-1.5% for rrnL. Phylogenetic analyses based on the cox1 sequences using the Bayesian inference indicated that all the G. intestinalis isolates grouped together with high statistical support. These findings demonstrated clearly the usefulness of mt cox1, nad5, and rrnL sequences for the molecular identification and for studying population genetics of G. intestinalis in horses.


Asunto(s)
Dípteros/genética , Genoma Mitocondrial , Animales , Composición de Base , ADN Mitocondrial/química , ADN Mitocondrial/aislamiento & purificación , ADN Mitocondrial/metabolismo , Dípteros/clasificación , Dípteros/crecimiento & desarrollo , Complejo IV de Transporte de Electrones/química , Complejo IV de Transporte de Electrones/clasificación , Complejo IV de Transporte de Electrones/genética , Complejo IV de Transporte de Electrones/metabolismo , Variación Genética , Caballos/parasitología , Larva/genética , NADH Deshidrogenasa/química , NADH Deshidrogenasa/clasificación , NADH Deshidrogenasa/genética , NADH Deshidrogenasa/metabolismo , Filogenia , Análisis de Secuencia de ADN
14.
Artículo en Inglés | MEDLINE | ID: mdl-23767599

RESUMEN

Quantum chaotic scattering is referred to as the study of quantum behaviors of open Hamiltonian systems that exhibit transient chaos in the classical limit. Traditionally a central issue in this field is how the elements of the scattering matrix or their functions fluctuate as a system parameter, e.g., the electron Fermi energy, is changed. A tacit hypothesis underlying previous works was that the underlying classical phase-space structure remains invariant as the parameter varies, so semiclassical theory can be used to explain various phenomena in quantum chaotic scattering. There are, however, experimental situations where the corresponding classical chaotic dynamics can change characteristically with some physical parameter. Multiple-terminal quantum dots are one such example where, when a magnetic field is present, the classical chaotic-scattering dynamics can change between being nonhyperbolic and being hyperbolic as the Fermi energy is changed continuously. For such systems semiclassical theory is inadequate to account for the characteristics of conductance fluctuations with the Fermi energy. To develop a general framework for quantum chaotic scattering associated with variable classical dynamics, we use multi-terminal graphene quantum-dot systems as a prototypical model. We find that significant conductance fluctuations occur with the Fermi energy even for fixed magnetic field strength, and the characteristics of the fluctuation patterns depend on the energy. We propose and validate that the statistical behaviors of the conductance-fluctuation patterns can be understood by the complex eigenvalue spectrum of the generalized, complex Hamiltonian of the system which includes self-energies resulted from the interactions between the device and the semi-infinite leads. As the Fermi energy is increased, complex eigenvalues with extremely smaller imaginary parts emerge, leading to sharp resonances in the conductance.


Asunto(s)
Modelos Químicos , Modelos Moleculares , Nanopartículas/química , Nanopartículas/ultraestructura , Dinámicas no Lineales , Teoría Cuántica , Simulación por Computador
15.
CNS Neurosci Ther ; 17(6): 605-11, 2011 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-20875045

RESUMEN

INTRODUCTION: Sevoflurane is well known to exert a neuroprotective effect through anesthetic preconditioning. However, its effects on postconditioning, a neuroprotective phenomenon following an insult, have not been well studied. AIMS: In this study, we examined the ability of sevoflurane to induce postconditioning in rat hippocampal slices, in vitro. RESULTS: 2%, 4%, and 6% sevoflurane reduced neurophysiologic and morphologic neuronal injury following oxygen-glucose deprivation (OGD) and reperfusion. The quantity of damaged neurons was significantly reduced on immunofluorescence staining; excitatory amino acids (Asp, Glu) increased and inhibitory amino acids (GABA) decreased significantly. The effect was concentration-dependent. CONCLUSION: Postconditioning with sevoflurane reduces neuronal damage after OGD-reperfusion injury in the CA1 area of rat hippocampus, in vitro.


Asunto(s)
Anestésicos por Inhalación/farmacología , Glucosa/deficiencia , Hipocampo/patología , Hipoxia Encefálica/tratamiento farmacológico , Éteres Metílicos/farmacología , Fármacos Neuroprotectores , Daño por Reperfusión/tratamiento farmacológico , Aminoácidos/líquido cefalorraquídeo , Aminoácidos/metabolismo , Animales , Colorantes , Fenómenos Electrofisiológicos , Potenciales Evocados/fisiología , Técnica del Anticuerpo Fluorescente , Hipocampo/efectos de los fármacos , Hipoxia Encefálica/patología , Masculino , Microscopía Electrónica , Microscopía Fluorescente , Neuronas/patología , Neurotransmisores/líquido cefalorraquídeo , Neurotransmisores/metabolismo , Propidio , Ratas , Ratas Sprague-Dawley , Daño por Reperfusión/patología , Sevoflurano
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