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Khalouf-Rivera J, Gamito J, Pérez-Bernal F, Arias JM, Pérez-Fernández P. Excited-state quantum phase transitions in the anharmonic Lipkin-Meshkov-Glick model: Dynamical aspects. Phys Rev E 2023; 107:064134. [PMID: 37464676 DOI: 10.1103/physreve.107.064134] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2023] [Accepted: 06/07/2023] [Indexed: 07/20/2023]
Abstract
The standard Lipkin-Meshkov-Glick (LMG) model undergoes a second-order ground-state quantum phase transition (QPT) and an excited-state quantum phase transition (ESQPT). The inclusion of an anharmonic term in the LMG Hamiltonian gives rise to a second ESQPT that alters the static properties of the model [Gamito et al., Phys. Rev. E 106, 044125 (2022)2470-004510.1103/PhysRevE.106.044125]. In the present work, the dynamical implications associated to this new ESQPT are analyzed. For that purpose, a quantum quench protocol is defined on the system Hamiltonian that takes an initial state, usually the ground state, into a complex excited state that evolves on time. The impact of the new ESQPT on the time evolution of the survival probability and the local density of states after the quantum quench, as well as on the Loschmidt echoes and the microcanonical out-of-time-order correlator (OTOC) are discussed. The anharmonity-induced ESQPT, despite having a different physical origin, has dynamical consequences similar to those observed in the ESQPT already present in the standard LMG model.
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Affiliation(s)
- J Khalouf-Rivera
- Departamento de Física Aplicada III, Escuela Técnica Superior de Ingeniería, Universidad de Sevilla, 41092 Sevilla, Spain
- Departamento de Ciencias Integradas y Centro de Estudios Avanzados en Física, Matemáticas y Computación, Universidad de Huelva, Huelva 21071, Spain
| | - J Gamito
- Departamento de Física Atómica, Molecular y Nuclear, Facultad de Física, Universidad de Sevilla, Apartado 1065, E-41080 Sevilla, Spain
| | - F Pérez-Bernal
- Departamento de Ciencias Integradas y Centro de Estudios Avanzados en Física, Matemáticas y Computación, Universidad de Huelva, Huelva 21071, Spain
- Instituto Carlos I de Física Teórica y Computacional, Universidad de Granada, Fuentenueva s/n, 18071 Granada, Spain
| | - J M Arias
- Departamento de Física Atómica, Molecular y Nuclear, Facultad de Física, Universidad de Sevilla, Apartado 1065, E-41080 Sevilla, Spain
- Instituto Carlos I de Física Teórica y Computacional, Universidad de Granada, Fuentenueva s/n, 18071 Granada, Spain
| | - P Pérez-Fernández
- Departamento de Física Aplicada III, Escuela Técnica Superior de Ingeniería, Universidad de Sevilla, 41092 Sevilla, Spain
- Instituto Carlos I de Física Teórica y Computacional, Universidad de Granada, Fuentenueva s/n, 18071 Granada, Spain
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2
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Gamito J, Khalouf-Rivera J, Arias JM, Pérez-Fernández P, Pérez-Bernal F. Excited-state quantum phase transitions in the anharmonic Lipkin-Meshkov-Glick model: Static aspects. Phys Rev E 2022; 106:044125. [PMID: 36397542 DOI: 10.1103/physreve.106.044125] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2022] [Accepted: 08/15/2022] [Indexed: 06/16/2023]
Abstract
The basic Lipkin-Meshkov-Glick model displays a second-order ground-state quantum phase transition and an excited-state quantum phase transition (ESQPT). The inclusion of an anharmonic term in the Hamiltonian implies a second ESQPT of a different nature. We characterize this ESQPT using the mean field limit of the model. The alternative ESQPT, associated with the changes in the boundary of the finite Hilbert space of the system, can be properly described using the order parameter of the ground-state quantum phase transition, the energy gap between adjacent states, the participation ratio, and the quantum fidelity susceptibility.
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Affiliation(s)
- J Gamito
- Departamento de Física Atómica, Molecular y Nuclear, Facultad de Física, Universidad de Sevilla, Apartado 1065, 41080 Sevilla, Spain
| | - J Khalouf-Rivera
- Departamento de Ciencias Integradas y Centro de Estudios Avanzados en Física, Matemáticas y Computación, Universidad de Huelva, Huelva 21071, Spain
| | - J M Arias
- Departamento de Física Atómica, Molecular y Nuclear, Facultad de Física, Universidad de Sevilla, Apartado 1065, 41080 Sevilla, Spain
- Instituto Carlos I de Física Teórica y Computacional, Universidad de Granada, Fuentenueva s/n, 18071 Granada, Spain
| | - P Pérez-Fernández
- Instituto Carlos I de Física Teórica y Computacional, Universidad de Granada, Fuentenueva s/n, 18071 Granada, Spain
- Departamento de Física Aplicada III, Escuela Técnica Superior de Ingeniería, Universidad de Sevilla, 41092 Sevilla, Spain
| | - F Pérez-Bernal
- Departamento de Ciencias Integradas y Centro de Estudios Avanzados en Física, Matemáticas y Computación, Universidad de Huelva, Huelva 21071, Spain
- Instituto Carlos I de Física Teórica y Computacional, Universidad de Granada, Fuentenueva s/n, 18071 Granada, Spain
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Relaño A, Dukelsky J, Pérez-Fernández P, Arias JM. Quantum phase transitions of atom-molecule Bose mixtures in a double-well potential. Phys Rev E Stat Nonlin Soft Matter Phys 2014; 90:042139. [PMID: 25375470 DOI: 10.1103/physreve.90.042139] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2014] [Indexed: 06/04/2023]
Abstract
The ground state and spectral properties of Bose gases in double-well potentials are studied in two different scenarios: (i) an interacting atomic Bose gas, and (ii) a mixture of an atomic gas interacting with diatomic molecules. A ground state second-order quantum phase transition is observed in both scenarios. For large attractive values of the atom-atom interaction, the ground state is degenerate. For repulsive and small attractive interaction, the ground state is not degenerate and is well approximated by a boson coherent state. Both systems depict an excited state quantum phase transition. In both cases, a critical energy separates a region in which all the energy levels are degenerate in pairs, from another region in which there are no degeneracies. For the atomic system, the critical point displays a singularity in the density of states, whereas this behavior is largely smoothed for the mixed atom-molecule system.
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Affiliation(s)
- A Relaño
- Departamento de Física Aplicada I and GISC, Universidad Complutense de Madrid, 28040 Madrid, Spain
| | - J Dukelsky
- Instituto de Estructura de la Materia, CSIC, Serrano 123, 28006 Madrid, Spain
| | - P Pérez-Fernández
- Departamento de Física Aplicada III, Universidad de Sevilla, Sevilla, Spain
| | - J M Arias
- Departamento de Física Atómica, Molecular y Nuclear, Universidad de Sevilla and Unidad Asociada to IEM (CSIC) Madrid, Spain
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Pérez-Fernández P, Relaño A, Arias JM, Cejnar P, Dukelsky J, García-Ramos JE. Excited-state phase transition and onset of chaos in quantum optical models. Phys Rev E Stat Nonlin Soft Matter Phys 2011; 83:046208. [PMID: 21599271 DOI: 10.1103/physreve.83.046208] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2010] [Revised: 12/16/2010] [Indexed: 05/30/2023]
Abstract
We study the critical behavior of excited states and its relation to order and chaos in the Jaynes-Cummings and Dicke models of quantum optics. We show that both models exhibit a chain of excited-state quantum phase transitions demarcating the upper edge of the superradiant phase. For the Dicke model, the signatures of criticality in excited states are blurred by the onset of quantum chaos. We show that the emergence of quantum chaos is caused by the precursors of the excited-state quantum phase transition.
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Affiliation(s)
- P Pérez-Fernández
- Departamento de Física Atómica, Molecular y Nuclear, Facultad de Física, Universidad de Sevilla, Apartado 1065, E-41080 Sevilla, Spain
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Vitko I, Bidaud I, Arias JM, Mezghrani A, Lory P, Perez-Reyes E. The I-II loop controls plasma membrane expression and gating of Ca(v)3.2 T-type Ca2+ channels: a paradigm for childhood absence epilepsy mutations. J Neurosci 2007; 27:322-30. [PMID: 17215393 PMCID: PMC6672065 DOI: 10.1523/jneurosci.1817-06.2007] [Citation(s) in RCA: 92] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Calcium currents via low-voltage-activated T-type channels mediate burst firing, particularly in thalamic neurons. Considerable evidence supports the hypothesis that overactive T-channels may contribute to thalamocortical dysrhythmia, including absence epilepsy. Single nucleotide polymorphisms in one of the T-channel genes (CACNA1H, which encodes Ca(v)3.2) are associated with childhood absence epilepsy in a Chinese population. Because only a fraction of these polymorphisms are predicted to increase channel activity and neuronal firing, we hypothesized that other channel properties may be affected. Here we describe that all the polymorphisms clustered in the intracellular loop connecting repeats I and II (I-II loop) increase the surface expression of extracellularly tagged Ca(v)3.2 channels. The functional domains within the I-II loop were then mapped by deletion analysis. The first 62 amino acids of the loop (post IS6) are involved in regulating the voltage dependence of channel gating and inactivation. Similarly, the last 15 amino acids of the loop (pre IIS1) are involved in channel inactivation. In contrast, the central region of I-II loop regulates surface expression, with no significant effect on channel biophysics. Electrophysiology, luminometry, fluorescence-activated cell sorting measurements, and confocal microscopy studies demonstrate that deletion of this central region leads to enhanced surface expression of channels from intracellular compartments to the plasma membrane. These results provide novel insights into how CACNA1H polymorphisms may contribute to Ca(v)3.2 channel overactivity and consequently to absence epilepsy and establish the I-II loop as an important regulator of Ca(v)3.2 channel function and expression.
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Affiliation(s)
- Iuliia Vitko
- Department of Pharmacology, University of Virginia, Charlottesville, Virginia 22904, and
| | - Isabelle Bidaud
- Departement de Physiologie, Institut de Génomique Fonctionnelle, Centre National de la Recherche Scientifique, Unité Mixte de Recherche 5203, Institut National de la Santé et de la Recherche Médicale, Unité 661, Université Montpellier I et II, 34090 Montpellier, France
| | - Juan Manuel Arias
- Department of Pharmacology, University of Virginia, Charlottesville, Virginia 22904, and
| | - Alexandre Mezghrani
- Departement de Physiologie, Institut de Génomique Fonctionnelle, Centre National de la Recherche Scientifique, Unité Mixte de Recherche 5203, Institut National de la Santé et de la Recherche Médicale, Unité 661, Université Montpellier I et II, 34090 Montpellier, France
| | - Philippe Lory
- Departement de Physiologie, Institut de Génomique Fonctionnelle, Centre National de la Recherche Scientifique, Unité Mixte de Recherche 5203, Institut National de la Santé et de la Recherche Médicale, Unité 661, Université Montpellier I et II, 34090 Montpellier, France
| | - Edward Perez-Reyes
- Department of Pharmacology, University of Virginia, Charlottesville, Virginia 22904, and
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Alonso CE, Arias JM, Vitturi A. Critical-point symmetries in boson-fermion systems: the case of shape transitions in odd nuclei in a multiorbit model. Phys Rev Lett 2007; 98:052501. [PMID: 17358851 DOI: 10.1103/physrevlett.98.052501] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2006] [Revised: 11/29/2006] [Indexed: 05/14/2023]
Abstract
We investigate phase transitions in boson-fermion systems. We propose an analytically solvable model [E(5/12)] to describe odd nuclei at the critical point in the transition from the spherical to gamma-unstable behavior. In the model, a boson core described within the Bohr Hamiltonian interacts with an unpaired particle assumed to be moving in the three single-particle orbitals j=1/2, 3/2, 5/2. Energy spectra and electromagnetic transitions at the critical point compare well with the results obtained within the interacting boson-fermion model, with a boson-fermion Hamiltonian that describes the same physical situation.
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Affiliation(s)
- C E Alonso
- Departamento de Física Atómica, Molecular y Nuclear, Facultad de Física, Universidad de Sevilla, Apartado 1065, 41080 Sevilla, Spain
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7
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Arias JM, Murbartián J, Vitko I, Lee JH, Perez-Reyes E. Transfer of β subunit regulation from high to low voltage-gated Ca2+
channels. FEBS Lett 2005; 579:3907-12. [PMID: 15987636 DOI: 10.1016/j.febslet.2005.06.008] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2005] [Revised: 06/01/2005] [Accepted: 06/08/2005] [Indexed: 11/21/2022]
Abstract
High voltage-activated Ca(2+) channel expression and gating is controlled by their beta subunits. Although the sites of interaction are known at the atomic level, how beta modulates gating remains to be determined. Using a chimeric approach, beta subunit regulation was conferred to a low voltage-activated channel. Regulation was dependent on a rigid linker connecting the alpha(1) interaction domain to IS6. Chimeric channels also revealed a role for IS6 in channel gating. Taken together, these results support a direct coupling model where beta subunits alter movements in IS6 that occur as the channel transits between closed, open, and inactivated states.
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Affiliation(s)
- Juan Manuel Arias
- Department of Pharmacology, University of Virginia, Charlottesville, VA 22908, USA
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Arias JM, García-Ramos JE, Dukelsky J. Phase diagram of the proton-neutron interacting boson model. Phys Rev Lett 2004; 93:212501. [PMID: 15601001 DOI: 10.1103/physrevlett.93.212501] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/02/2004] [Revised: 09/03/2004] [Indexed: 05/24/2023]
Abstract
We study the phase diagram of the proton-neutron interacting boson model with special emphasis on the phase transitions leading to triaxial phases. The existence of a new critical point between spherical and triaxial shapes is reported.
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Affiliation(s)
- J M Arias
- Departamento de Física Atómica, Molecular y Nuclear, Facultad de Física, Universidad de Sevilla, Apartado 1065, 41080 Sevilla, Spain
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Abstract
Low-voltage-activated T-type (Cav3) Ca2+ channels produce low-threshold spikes that trigger burst firing in many neurons. The CACNA1I gene encodes the Cav3.3 isoform, which activates and inactivates much more slowly than the other Cav3 channels. These distinctive kinetic features, along with its brain-region-specific expression, suggest that Cav3.3 channels endow neurons with the ability to generate long-lasting bursts of firing. The human CACNA1I gene contains two regions of alternative splicing: variable inclusion of exon 9 and an alternative acceptor site within exon 33, which leads to deletion of 13 amino acids (Delta33). The goal of this study is to determine the functional consequences of these variations in the full-length channel. The cDNA encoding these regions were cloned using RT-PCR from human brain, and currents were recorded by whole cell patch clamp. Introduction of the Delta33 deletion slowed the rate of channel opening. Addition of exon 9 had little effect on kinetics, whereas its addition to Delta33 channels unexpectedly slowed both activation and inactivation kinetics. Modeling of neuronal firing showed that exon 9 or Delta33 alone reduced burst firing, whereas the combination enhanced firing. The major conclusions of this study are that the intracellular regions after repeats I and IV play a role in channel gating, that their effects are interdependent, suggesting a direct interaction, and that splice variation of Cav3.3 channels provides a mechanism for fine-tuning the latency and duration of low-threshold spikes.
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Affiliation(s)
- Janet Murbartián
- Department of Pharmacology, University of Virginia, Charlottesville, Virginia 22908-0735, USA
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Arias JM, Dukelsky J, García-Ramos JE. Quantum phase transitions in the interacting boson model: integrability, level repulsion, and level crossing. Phys Rev Lett 2003; 91:162502. [PMID: 14611396 DOI: 10.1103/physrevlett.91.162502] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/20/2003] [Indexed: 05/24/2023]
Abstract
We study the quantum phase transition mechanisms that arise in the interacting boson model. We show that the second-order nature of the phase transition from U(5) to O(6) may be attributed to quantum integrability, whereas all the first-order phase transitions of the model are due to level repulsion with one singular point of level crossing. We propose a model Hamiltonian with a true first-order phase transition for finite systems due to level crossings.
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Affiliation(s)
- J M Arias
- Departamento de Física Atómica, Molecular y Nuclear, Facultad de Física, Universidad de Sevilla, Apartado 1065, 41080 Sevilla, Spain
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Merroun ML, Ben Chekroun K, Arias JM, González-Muñoz MT. Lanthanum fixation by Myxococcus xanthus: cellular location and extracellular polysaccharide observation. Chemosphere 2003; 52:113-120. [PMID: 12729693 DOI: 10.1016/s0045-6535(03)00220-0] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Myxococcus xanthus is a soil bacterium of the myxobacteria group and is abundant in almost all soils. Its role in soil ecology is considered significant. One noteworthy characteristic of the bacterium is that it produces large quantities of extracellular polymeric substances (EPS). It is also known that its biomass has the capacity to fix heavy metals. Here it is reported that M. xanthus was able to accumulate 0.6 mmol of La per g of wet biomass and/or 0.99 mmol per g of dry biomass. Transmission Electron Microscopy (TEM) observation of M. xanthus cells treated with La showed that a substantial amount of this cation was fixed in the EPS and in the cell wall. Smaller amounts were also observed in the cytoplasm. Fixed La appeared as phosphate in all cellular locations. The results given here also show that the use of La enables TEM observation of the M. xanthus EPS as a dense fibrillar net surrounding the cells. This technique is relatively easy and prevents EPS collapse, which occurs frequently during the fixation and dehydration procedures commonly used in preparations for TEM observations. Since antibodies are no longer required, the La stain can be carried out without delaying bacterial cell cultivation or isolation. In addition, the presence of La in cell cytoplasm without cell degeneration suggests that this microorganism could be used as a model in the study of bacteria-lanthanide interactions.
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Affiliation(s)
- M L Merroun
- Departamento de Microbiologi;a, Facultad de Ciencias, Universidad de Granada, Avda. Fuentenueva s/n, 18071, Granada, Spain
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12
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Abstract
We describe the cloning of a cDNA from a human testis library that encodes a novel protein with similarity to one repeat of voltage-gated Ca(2+) channels (Ca(v)). Northern and dot blot analyses indicate that the novel Ca(v)-like gene is expressed predominantly in testis and at lower levels in many other tissues. Heterologous expression of the Ca(v)-like protein did not lead to the induction of any detectable ionic current and failed to modify intracellular Ca(2+) concentrations. Similar one-repeat Ca(v)-like proteins have been cloned from Bacillus, Mus, and Homo, and appear to encode ion channels involved in renal function, axis determination, and sperm motility.
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Affiliation(s)
- Juan Manuel Arias
- Department of Pharmacology, University of Virginia, P.O. Box 800735, 1300 Jefferson Park Avenue, Charlottesville 22908-0735, VA, USA
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13
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Murbartián J, Arias JM, Lee JH, Gomora JC, Perez-Reyes E. Alternative splicing of the rat Cav
3.3 T-type calcium channel gene produces variants with distinct functional properties1. FEBS Lett 2002; 528:272-8. [PMID: 12297319 DOI: 10.1016/s0014-5793(02)03341-0] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Molecular diversity in T-type Ca(2+) channels is produced by expression of three genes, and alternative splicing of those genes. Prompted by differences noted between rat and human Ca(v)3.3 sequences, we searched for splice variants. We cloned six variants, which are produced by splicing at exon 33 and exon 34. Expression of the variants differed between brain regions. The electrophysiological properties of the variants displayed similar voltage-dependent gating, but differed in their kinetic properties. The functional impact of splicing was inter-related, suggesting an interaction. We conclude that alternative splicing of the Ca(v)3.3 gene produces channels with distinct properties.
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Affiliation(s)
- Janet Murbartián
- Department of Pharmacology, University of Virginia, P.O. Box 800735, Charlottesville 22908-0735, USA
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14
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Abstract
The full-length human Ca(v)3.3 (alpha(1I)) T-type channel was cloned, and found to be longer than previously reported. Comparison of the cDNA sequence to the human genomic sequence indicates the presence of an additional 4-kb exon that adds 214 amino acids to the carboxyl terminus and encodes the 3' untranslated region. The electrophysiological properties of the full-length channel were studied after transient transfection into 293 human embryonic kidney cells using 5 mM Ca(2+) as charge carrier. From a holding potential of -100 mV, step depolarizations elicited inward currents with an apparent threshold of -70 mV, a peak of -30 mV, and reversed at +40 mV. The kinetics of channel activation, inactivation, deactivation, and recovery from inactivation were very similar to those reported previously for rat Ca(v)3.3. Similar voltage-dependent gating and kinetics were found for truncated versions of human Ca(v)3.3, which lack either 118 or 288 of the 490 amino acids that compose the carboxyl terminus. A major difference between these constructs was that the full-length isoform generated twofold more current. These results suggest that sequences in the distal portion of Ca(v)3.3 play a role in channel expression. Studies on the voltage-dependence of activation revealed that a fraction of channels did not gate as low voltage-activated channels, requiring stronger depolarizations to open. A strong depolarizing prepulse (+100 mV, 200 ms) increased the fraction of channels that gated at low voltages. In contrast, human Ca(v)3.3 isoforms with shorter carboxyl termini were less affected by a prepulse. Therefore, Ca(v)3.3 is similar to high voltage-activated Ca(2+) channels in that depolarizing prepulses can regulate their activity, and their carboxy termini play a role in modulating channel activity.
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Affiliation(s)
- Juan Carlos Gomora
- Department of Pharmacology, University of Virginia, Charlottesville, Virginia 22908, USA
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15
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Abstract
AIMS To search for and study the genes involved in the regulation of phosphate in the soil developmental bacterium Myxococcus xanthus. METHODS AND RESULTS The mlpB gene encoding a 149 residue polypeptide was identified while screening for genes with products related to phosphate metabolism. The amino terminal 19 residues of MlpB encode a typical prokaryotic signal sequence with a putative lipoprotein cleavage site. CONCLUSIONS In this study, a new myxobacterial putative lipoprotein is reported. The data suggest that MlpB may be involved in the secretion of phosphate-related proteins. SIGNIFICANCE AND IMPACT OF THE STUDY Soil bacteria have complex regulatory systems for using inorganic phosphate. This nutrient is limiting in the environment, and has a critical importance for growth and in the initiation of differentiation for developmental bacteria. A number of proteins are involved in all these processes, including membrane lipoproteins, which are being increasingly studied in M. xanthus.
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Affiliation(s)
- M Martinez-Canamero
- Departamento de Microbiologia, Facultad de Ciencias, Universidad de Granada, Spain.
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16
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Abstract
This paper deals with lead biosorption by Myxococcus xanthus biomass in which dry biomass, accumulating up to 1.28 mmol of lead g(-1), is demonstrated to be a more efficient biosorbent than wet biomass. Dry biomass biosorption was found to be very rapid, reaching equilibrium after 5-10 min. Culture age, the initial lead concentration and pH affected this process, but temperature did not. Furthermore, by using sodium citrate as a desorbent agent, 92.17% of the biosorbed lead could be recovered. It was also established that the biosorbed lead is located on the cellular wall and within the characteristic extracellular polysaccharide of this micro-organism.
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Affiliation(s)
- M L Merroun
- Departamento de Microbiología, Facultad de Ciencias, Universidad de Granada, Granada, Spain
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17
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García-Granados A, Gutiérrez MC, Rivas F, Arias JM. Biotransformation of 4beta-hydroxyeudesmane-1,6-dione by Gliocladium roseum and Exserohilum halodes. Phytochemistry 2001; 58:891-895. [PMID: 11684186 DOI: 10.1016/s0031-9422(01)00340-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Biotransformation of sesquiterpene 4beta-hydroxyeudesmane-1,6-dione by the filamentous fungi Gliocladium roseum and Exserohilum halodes was achieved. With Exserohilum halodes, only one metabolite was obtained, as a result of the regio- and stereoselective reduction of the keto group at C-1, which is difficult to achieve by chemical means. Five metabolites were produced with Gliocladium roseum, three of which, the 7alpha-hydroxylated, the 7alpha,11- and the 1alpha,8alpha-dihydroxylated derivatives, have not previously been reported. The hydroxylation at C-11 is the main action of this microorganism. These 11-hydroxylated compounds can be chemically transformed into 6beta,12-eudesmanolides.
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Affiliation(s)
- A García-Granados
- Departamento de Química Orgánica, Facultad de Ciencias, Universidad de Granada, 18071, Granada, Spain.
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Moraleda-Muñoz A, Carrero-Lérida J, Extremera AL, Arias JM, Muñoz-Dorado J. Glycerol 3-phosphate inhibits swarming and aggregation of Myxococcus xanthus. J Bacteriol 2001; 183:6135-9. [PMID: 11567014 PMCID: PMC99693 DOI: 10.1128/jb.183.20.6135-6139.2001] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We have cloned a gene of Myxococcus xanthus with similarities to the permease for glycerol 3-phosphate (G3P) of other bacteria. Expression of the gene increased significantly during the first hours of starvation. Swarming of the wild-type strain was inhibited and aggregation was delayed by G3P. Conversely, a DeltaglpT strain aggregated even on rich medium. These results indicate that G3P may function to regulate the timing of aggregation in M. xanthus.
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Affiliation(s)
- A Moraleda-Muñoz
- Departamento de Microbiología, Facultad de Ciencias, Universidad de Granada, Granada, Spain
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García-Granados A, Melguizo E, Parra A, Simeó Y, Viseras B, Dobado JA, Molina J, Arias JM. Regioselective enzymatic acylations of polyhydroxylated eudesmanes: semisynthesis, theoretical calculations, and biotransformation of cyclic sulfites. J Org Chem 2000; 65:8214-23. [PMID: 11101376 DOI: 10.1021/jo0008183] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Different lipase enzymes have been tested in order to perform regioselective acetylations on the eudesmane tetrol from vulgarin. High yields (95%) of 1,12-diacetoxy derivative (4) were achieved in 1 h with Candida antarctica lipase (CAL). However, only the 12-acetyl derivative (6) was obtained in similar yield with Mucor miehei (MML) or Candida cylindracea (CCL) lipases. The enzymatic protection at C-1 and C-12 has been used to form eudesmane cyclic-sulfites between C-6 and C-4 atoms. The R/S-sulfur configuration has been assigned by means of the experimental and theoretical (13)C and (1)H NMR chemical shifts. The theoretical shifts were calculated using the GIAO method, with a MM+ geometry optimization followed by a single-point calculation at the B3LYP/6-31G(*) level (B3LYP/6-31G(*)//MM+). Moreover, B3LYP/6-31G(*) geometry optimizations were carried out to test the B3LYP/6-31G(*)//MM+ results, for the deacetylated sulfites (12 and 15). In addition to the delta(C) and delta(H) shifts, the (3)J(HH) coupling constants were also calculated and compared with the experimental values when available. Finally, different reactivities have been checked in both sulfites by biotransformation with Rhizopus nigricans. While the R-sulfite gave 2 alpha- and 11 beta-hydroxylated metabolites, the S-sulfite yielded only regioselective deacetylations. Furthermore, both sulfites showed different reactivities in redox processes.
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Affiliation(s)
- A García-Granados
- Departamento de Química Orgánica, Facultad de Ciencias, Universidad de Granada, 18071-Granada, Spain.
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Gutierrez AA, Arias JM, García L, Mas-Oliva J, Guerrero-Hernández A. Activation of a Ca2+-permeable cation channel by two different inducers of apoptosis in a human prostatic cancer cell line. J Physiol 1999; 517 ( Pt 1):95-107. [PMID: 10226152 PMCID: PMC2269326 DOI: 10.1111/j.1469-7793.1999.0095z.x] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
1. We have combined patch clamp recording with simultaneous [Ca2+]i measurements in single LNCaP cells (a human prostate cancer cell line), to study the activation of Ca2+-permeable channels by two different inducers of apoptosis, ionomycin and serum deprivation. 2. In perforated patch recording, LNCaP cells had a membrane potential of -40 mV and a resting [Ca2+]i of 90 nM. Application of ionomycin at levels that induced apoptosis in these cells (10 microM) produced a biphasic increase in [Ca2+]i. The first rise in [Ca2+]i was due to release of Ca2+ from internal stores and it was associated with a membrane hyperpolarization to -77 mV. The latter was probably due to the activation of high conductance, Ca2+- and voltage-dependent K+ channels (maxi-K). Conversely, the second rise in [Ca2+]i was always preceded by and strictly associated with membrane depolarization and required external Ca2+. Serum deprivation, another inducer of apoptosis, unmasked a voltage-independent Ca2+ permeability as well. 3. A lower concentration of ionomycin (1 microM) did not induce apoptosis, and neither depolarized LNCaP cells nor produced the biphasic increase in [Ca2+]i. However, the first increment in [Ca2+]i due to release from internal Ca2+ stores was evident at this concentration of ionomycin. 4. Simultaneous recordings of [Ca2+]i and ion channel activity in the cell attached configuration of patch clamp revealed a Ca2+-permeable, Ca2+-independent, non-selective cation channel of 23 pS conductance. This channel was activated only during the second increment in [Ca2+]i induced by ionomycin. The absence of serum activated the 23 pS channel as well, albeit at a lower frequency than with ionomycin. 5. Thus, the 23 pS channel can be activated by two unrelated inducers of apoptosis and it could be another Ca2+ influx mechanism in programmed cell death of LNCaP cells.
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Affiliation(s)
- A A Gutierrez
- Departamento de Bioquímica, Instituto de Fisiología Celular, Universidad Nacional Autonoma de Mexico, Mexico DF 04510, Mexico
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21
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Martínez JM, Prieto I, Ramírez MJ, de Gasparo M, Hermoso F, Arias JM, Alba F, Ramírez M. Sex differences and age-related changes in human serum aminopeptidase A activity. Clin Chim Acta 1998; 274:53-61. [PMID: 9681597 DOI: 10.1016/s0009-8981(98)00049-7] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Given that aminopeptidase A is primarily responsible for cleaving aspartic acid and converting angiotensin II to angiotensin III, the purpose of the present study was to evaluate the activity of aminopeptidase A by determination of glutamate aminopeptidase activity (GluAP) and aspartate aminopeptidase activity (AspAP) (reported respectively as aminopeptidase A and angiotensinase A activities) in human serum during development and ageing, in an apparently healthy population of 139 male and 148 female subjects. To measure GluAP and AspAP we used glutamyl- and aspartyl-2-naphthylamide as substrates. Significant age-related increases were observed in GluAP activity in males and females and in AspAP activity in females. In males, there were no age-related differences in AspAP activity. A significant correlation was observed between age and GluAP activity in the population analysed as a whole or according to sex. No correlation was demonstrated between age and AspAP activity either in the whole population or according to sex. These results may reflect the evolution of the functional status of susceptible circulating substrates during development and ageing.
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Ben Omar N, Arias JM, González-Muñoz MT. Extracellular bacterial mineralization within the context of geomicrobiology. Microbiologia 1997; 13:161-72. [PMID: 9253756] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
In the biosphere, bacteria can function as geochemical agents, promoting the dispersion, fractionation and/or concentration of matter. These processes, which are being more and more valued from the point of view of various scientific disciplines, have given rise to the field of geomicrobiology. At the same time, microbial processes resulting in the concentration of matter and thus inducing the formation of minerals, constitute an area of research of growing interest known as biomineralization. In this review a succinct summary of various aspects of both disciplines has been offered together with a more detailed review of those aspects related to extracellular bacterial mineralization. The significance of the role played by the metabolism of bacteria is discussed along with the results of recent research on the role of dead bacteria and bacterial remains that act as heterogeneous nuclei of crystallization. The role played by the membranes of bacteria has also been considered to be highly relevant, and a discussion concerning their possible value as models for both the study of more complex biomineralization processes as well as application in the field of biomimetic materials is put forward.
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Affiliation(s)
- N Ben Omar
- Department of Microbiology, Faculty of Science, University of Granada, Spain
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Morton KA, Pisani DE, Whiting JH, Cheung AK, Arias JM, Valdivia S. Determination of glomerular filtration rate using technetium-99m-DTPA with differing degrees of renal function. J Nucl Med Technol 1997; 25:110-4. [PMID: 9239614] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
UNLABELLED Glomerular filtration rate (GFR) is an important index of renal function. Twenty-four-hour creatinine clearance overestimates GFR in patients with poor renal function. Inulin and iothalamate clearances are accepted reference standards for determining GFR but are expensive and laborious. We have previously reported that GFRs obtained by measuring the disappearance of 99mTc-DTPA from ultrafiltered (protein-free) samples of plasma were virtually identical to those obtained by the iothalamate method. However, the subjects used in that study had normal to only moderately decreased renal function. METHODS The accuracy of measuring GFR by plasma clearance of 99mTc-DTPA was determined in subjects where renal function varied from normal to severely impaired. In all subjects, GFR was established by clearance of 125I-iothalamate from urine and serum and was used as the standard of reference. RESULTS For subjects with normal to moderately diminished renal function (GFR > 20 ml/min), the correlation between values of GFR obtained by the DTPA and iothalamate methods was high (n = 18, r = 0.966). The difference between the pairs of GFR values obtained by the two methods was not statistically significant (p > 0.1). In patients with severe renal insufficiency (GFR < 20 ml/min), the correlation between the DTPA and iothalamate methods was poor (n = 11, r = 0.236), and the GFR values obtained by the two methods were statistically different (p < 0.01). CONCLUSION These results suggest that GFR can be determined accurately by plasma clearance of 99mTc-DTPA in all patients except those with severe renal insufficiency.
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Affiliation(s)
- K A Morton
- Imaging Service, VA Medical Center, Portland, Oregon 97207, USA
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24
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Lee TT, Arias JM, Andrus HL, Quencer RM, Falcone SF, Green BA. Progressive posttraumatic myelomalacic myelopathy: treatment with untethering and expansive duraplasty. J Neurosurg 1997; 86:624-8. [PMID: 9120625 DOI: 10.3171/jns.1997.86.4.0624] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Patients with progressive posttraumatic myelomalacic myelopathy (PPMM), or tethered cord syndrome, present with symptoms and signs similar to those observed in case of progressive posttraumatic cystic myelopathy, that is, sensorimotor function deterioration, local and/or radicular pain, increased spasticity, increased autonomic dysreflexia, and sphincter dysfunction. The authors investigated surgical outcomes of untethering combined with expansive duraplasty. Forty patients with PPMM who presented with functional deterioration underwent untethering of the spinal cord and nerve roots with an expansive duraplasty. Meticulous dissections of adhesions on the dorsal and lateral aspects of the spinal cord and nerve roots were performed. Intraoperative ultrasonography was used to detect the presence of a confluent cyst and to assess the success of untethering. After surgery, the patients were treated using a protocol that involved frequent turning for 48 hours and subsequently mobilization. Preoperative magnetic resonance (MR) imaging, with and without administration of a contrast agent, was obtained in all patients, except one patient who underwent immediate and delayed computerized tomography (CT) myelography. The mean follow-up period was 3 years (range 20-57 months) for the 36 patients available for follow-up review. Spinal cord tethering was observed in all patients preoperatively. Trauma was the most common cause of this pathology, accounting for 31 of the 40 cases. Preoperative MR imaging did not demonstrate tumor recurrence in the group of five patients who had undergone an initial operation for tumor excision. The interval between the causative event and the operation was less than 5 years in half of the patients (20 of 40), with the longest interval lasting up to 37 years. Motor function deterioration was the most frequent manifestation; it was present in 31 of 40 patients. Improvements in motor function, autonomic dysreflexia, pain, sphincter dysfunction, and sensory function were found during the most recent follow-up examination in 79%, 75%, 62%, 50%, and 43% of the patients, respectively. Two patients experienced retethering of the spinal cord and one underwent a second operation. Surgical untethering and expansive duraplasty, followed by postoperative position rotation to avoid retethering, provide symptomatic relief for patients with PPMM.
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Affiliation(s)
- T T Lee
- Department of Neurological Surgery, University of Miami School of Medicine, Florida, USA
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Arias JM. [Enrique Montoya (1928-1996), a life dedicated to teaching and research]. Microbiologia 1997; 13:79-82. [PMID: 9131903] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Affiliation(s)
- J M Arias
- Departamento de Microbiología, Facultad de Ciencias, Universidad de Granada, España.
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Abstract
Yeast cells are capable of carrying out biosorption with various heavy metals. The biomass deriving from Saccharomyces cerevisiae coming from brewing industries is a by-product that is possible to be used in the purification of water contaminated with these ions. In this paper we show that yeast biomass from one of the city's breweries can adsorb uranium efficiently, up to 2.4 mmol of this metal per gram of dry biomass. It can also be seen that the temperature (between 10 degrees and 37 degrees C) has no effect on the biosorption, while pH does have an influence, 4.5 being the best value. When the concentrations of uranium range between 0.1 and 0.5 mol l-1 the yeast dry biomass is capable of adsorbing between 84% and 98% of this metal in solution.
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Affiliation(s)
- N B Omar
- Departamento de Microbiología, Facultad de Ciencias, Universidad de Granada, Spain
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27
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Muñoz-Dorado J, Arias JM. The social behavior of myxobacteria. Microbiologia 1995; 11:429-38. [PMID: 8588838] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Myxobacteria are social microorganisms that undergo a spectacular cell cycle. Under starvation conditions, cells aggregate to certain points originating macroscopic fruiting bodies, inside which cells differentiate into myxospores. To accomplish this developmental cycle, cells must communicate. The signals that cells exchange during development as well as the signal transduction systems used by myxobacteria have been intensively studied during the last years. A family of eukaryotic-like protein serine/threonine kinases has been identified in Myxococcus xanthus, indicating that signal transduction systems similar to those used by eukaryotic cells may also function in myxobacteria.
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Affiliation(s)
- J Muñoz-Dorado
- Departamento de Microbiología, Facultad de Ciencias, Universidad de Granada, España
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García-Granados A, Liñán E, Martínez A, Onorato ME, Arias JM. New polyoxygenated ent-manoyl oxides obtained by biotransformation with filamentous fungi. J Nat Prod 1995; 58:1695-1701. [PMID: 8594146 DOI: 10.1021/np50125a008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Incubation of methyl (13R)-ent-16-hydroxy-8 alpha,13-epoxylabd-14-en-18-oate [4] with Curvularia lunata yielded ent-1 beta-hydroxy [6] and ent-6 beta-hydroxy [7] derivatives, and that of methyl (13S)-ent-16-dihydroxy-8 alpha,13-epoxylabd-14-en-18-oate [5] with the same organism gave ent-11 beta-hydroxy [8], ent-6 beta-hydroxy [9], and ent-6 beta,11 beta-dihydroxy [10] derivatives. The incubation of substrates 4 and 5 with Fusarium moniliforme afforded ent-1 beta-hydroxy derivatives (6 and 14, respectively). Cunninghamella elegans produced ent-3 beta-hydroxy, ent-1 beta-hydroxy and ent-1 beta,3 beta-dihydroxy derivatives, and led to epoxidation of the double bond of the substrates. In addition, ent-3 beta,11 alpha-dihydroxy (as the acetoxy derivative 17) and ent-3 beta,11 beta-dihydroxy [12] derivatives were isolated from incubations of substrates 4 and 5, respectively. Compounds 7, 9-11, 14, 16-18, and 21 were characterized as new polyoxygenated ent-manoyl oxides.
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Muñoz Dorado J, Arias JM. Protein kinases and phosphatases during the developmental cycle of myxobacteria. Microbiologia 1995; 11:376-8. [PMID: 7576355] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Affiliation(s)
- J Muñoz Dorado
- Departamento de Microbiología, Facultad de Ciencias, Universidad de Granada
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Gómez-Camacho J, Arias JM, Nagarajan MA. Analytic description of the scattering of electrons by molecules. Phys Rev A 1995; 51:3799-3811. [PMID: 9912051 DOI: 10.1103/physreva.51.3799] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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García-Granados A, Liñán E, Martínez A, Onorato ME, Parra A, Arias JM. Synthesis of enantio-manoyl oxides: modifiers of the activity of adenylatecyclase enzyme. Phytochemistry 1995; 38:287-293. [PMID: 7772300 DOI: 10.1016/0031-9422(94)00549-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Cyclization of methyl ent-8 alpha-hydroxylabd-13(16),14-dien-18-oate with m-chloroperbenzoic acid gave methyl (13S)-ent-16-hydroxy-8 alpha,13-epoxylabd-14-en-18-oate and its epimer at C-13. Biotransformation of the former (which exhibits antileishmania activity) with Rhizopus nigricans cultures produced the methyl (13S)-ent-11 beta,16-dihydroxy-8 alpha,13-epoxilabd-14-en-18-oate (carbomanoyl, which inhibits the activity of the adenylatecyclase enzyme), methyl (13S)-ent-3 beta,16-dihydroxy-8 alpha,13-epoxilabd-14-en-18-oate, methyl (13S)-ent-3 beta,11 beta,16-trihydroxy-8 alpha,13-epoxilabd-14-en-18-oate and the (14S)-ent-3 beta-hydroxy-14,15-epoxy derivative that cyclized spontaneously to a spiran compound. Biotransformation of methyl (13S)-ent-16-hydroxy-3-oxo-8 alpha,13-epoxilabd-14-en-18-oate with R. nigricans produced ent-11 beta-hydroxylation, reduction of the keto group at C-3 (to give 3S-alcohol) and 14(S),15-epoxidation, which also rearranged to a spiro compound.
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Affiliation(s)
- A García-Granados
- Departamento de Química Orgánica, Facultad de Ciencias, Universidad de Granada, Spain
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Montoya MD, Gálvez A, Arias JM, Montoya E. Autolytic effect of the antibiotic produced by Myxococcus coralloides D. Microbiologia 1994; 10:395-402. [PMID: 7539617] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Myxococcus coralloides D secretes an antibiotic, named corallolysin, when grown on a rich medium. When a critical concentration is reached, this antibiotic lyses the producer bacterium either during vegetative growth or during morphogenesis. Corallolysin has not effect on resting cells nor on myxospores. The autolytic effect is caused by the early inhibition of RNA synthesis.
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Affiliation(s)
- M D Montoya
- Departamento de Microbiología, Facultad de Ciencias, Universidad de Granada
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García-Grandos A, Jiménez MB, Martínez A, Parra A, Rivas F, Arias JM. Chemical-microbiological synthesis of ent-13-epi-manoyl oxides with biological activities. Phytochemistry 1994; 37:741-747. [PMID: 7765688 DOI: 10.1016/s0031-9422(00)90350-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
The biotransformation of ent-13-epi-3-keto manoyl oxide, which possesses antileishmania activity, with Curvularia lunata produced ent-6 beta-hydroxy, ent-1 alpha-hydroxy, ent-11 beta-hydroxy and delta 1-derivatives, as well as a reduction product a C-3 (S-alcohol) with another hydroxyl group at C-6 (ent-6 beta) or C-11 (ent-11 beta). The ent-6 beta-hydroxy and delta 1-derivatives inhibited growth of the pathogenic protozoa, Leishmania donovani. The biotransformation of ent-12 alpha-acetoxy-3 beta-hydroxy-13-epi-manoyl oxide and ent-3 beta-acetoxy-12 beta-dihydroxy-13-epi-manoyl oxide gave ent-3 eta,12 beta-dihydroxy-13-epi-manoyl oxide and ent-3 beta,6 beta,12 beta-trihydroxy-13-epi-manoyl oxide (trimanoyl). Both products increased the activity of adenylatecyclase.
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Affiliation(s)
- A García-Grandos
- Departamento de Química Orgánica, Facultad de Ciencias, Universidad de Granada, Spain
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Pittel S, Arias JM, Dukelsky J, Frank A. Consistent baryon mapping of quark systems. Phys Rev C Nucl Phys 1994; 50:423-434. [PMID: 9969675 DOI: 10.1103/physrevc.50.423] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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Arias JM, Morton KA, Albro JE, Patch GG, Valdivia S, Greenberg HE, Christian PE, Datz FL. Comparison of methods for identifying early methotrexate-induced hepatotoxicity in patients with rheumatoid arthritis. J Nucl Med 1993; 34:1905-9. [PMID: 8229232] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Hepatotoxicity may complicate therapy with methotrexate in patients with rheumatoid arthritis. Prevention of cirrhosis may depend upon early identification of liver damage, usually accomplished by serial biopsy. To determine the adequacy of noninvasive methods for identifying hepatotoxicity, 22 sets of data were obtained in patients undergoing therapy with methotrexate for rheumatoid arthritis. Comparisons were made between liver biopsy, hepatocellular enzymes and two noninvasive radioisotopic methods that have been shown to be abnormal in hepatocellular disease: the rate constant of excretion of the 14C-aminopyrine and the time from injection to peak hepatic activity of 99mTc-diisopropylimidodiacetic acid. The hepatocellular enzymes and the time-to-peak-activity of diisopropylimidodiacetic acid were not useful predictors of methotrexate-induced hepatotoxicity. The aminopyrine breath test was abnormal in approximately half the patients with hepatotoxicity but showed poor specificity. Noninvasive methods remain inferior to biopsy for the detection of mild to moderate methotrexate-induced hepatotoxicity in patients with rheumatoid arthritis.
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Affiliation(s)
- J M Arias
- Department of Radiology, University of Utah, Salt Lake City
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Bauske I, Arias JM, Frank A, Friedrichs H, Heil RD, Herzberg R, Hoyler F, Kneissl U, Margraf J, Pitz HH, Wesselborg C, Zilges A. First observation of scissors mode states in an odd-mass nucleus. Phys Rev Lett 1993; 71:975-978. [PMID: 10055417 DOI: 10.1103/physrevlett.71.975] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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Abstract
The results of repair of 18 facial nerves were examined by means of a modified House-Brackmann grading system. Six were repaired by end-to-end anastomosis and 12 by nerve graft. The reliability of the simplified House-Brackmann grading system was also assessed, using the kappa statistic to analyze the agreement between pairs of observers who examined the function of 40 nerves in 37 patients. Facial nerves studied had been either preserved, repaired or grafted, or divided and treated by faciohypoglossal nerve anastomosis. One nerve was not treated. The grading system proved to be somewhat unreliable, with complete agreement between observers in only 25% of cases. Facial nerve repair produced a fair return of function in just under two-thirds of the cases. The ability of an examiner ignorant of the patient's history to assess from the end result how the nerve had been managed was also estimated. Observers showed little ability to decide correctly on the previous treatment of the nerve when the patient showed moderate dysfunction postoperatively. The implications of these findings for grading systems and for management of the facial nerve in acoustic nerve tumor surgery are discussed.
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Affiliation(s)
- T T King
- Department of Neurosurgery, Royal London Hospital, England
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Abstract
Myxococcus coralloides D produced cell-bound deoxyribonucleases (DNases) during the exponential phase of growth in liquid medium. DNase activity was much higher than that detected in other myxobacterial strains and was fractionated into three different peaks by filtration through Sephadex G-200. The DNases were named G, M and P. The optimum temperatures were 37 degrees C, 33 degrees C and 25 degrees C respectively, although high activities were recorded over the temperature range 20-45 degrees C. The pH range of high activity was between 6.0 and 9.0, with an optimum for each DNase at 8.0. DNases M and P were strongly inhibited by low concentrations of NaCl, but activity of DNase G was less affected by NaCl. The three activities required divalent metal ions as cofactors (especially Mg2+ and Mn2+); however, other metal ions (Fe2+, Ni2+, Zn2+) were inhibitors. The molecular weights were estimated by gel filtration chromatography and SDS-PAGE as 44 kDa (DNase G), 49 kDa (DNase M) and 39 kDa (DNase P).
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Patch GG, Morton KA, Arias JM, Datz FL. Naloxone reverses pattern of obstruction of the distal common bile duct induced by analgesic narcotics in hepatobiliary imaging. J Nucl Med 1991; 32:1270-2. [PMID: 1675267] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
It is widely known that narcotics, such as morphine, cause spasm of the sphincter of Oddi, increasing pressure in the common bile duct. This pharmacologic effect has been applied to hepatobiliary scintigraphy in patients with chronic cholecystitis or cholestasis to reducing the time required for a diagnostic study. However, this feature of narcotics could result in delayed or nonvisualization of the small bowel, simulating a distal common bile duct obstruction, in patients requiring parenteral narcotic analgesics who must undergo hepatobiliary scintigraphy. We report on three patients where administration of intravenous naloxone hydrochloride (Narcan), a narcotic antagonist, was helpful in distinguishing narcotic-induced spasm of the sphincter of Oddi from true obstruction of the common bile duct.
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Affiliation(s)
- G G Patch
- Department of Radiology, University of Utah School of Medicine, Salt Lake City
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Gonzalez F, Montoya MD, Fárez E, Arias JM, Montoya E. Effect of phosphate on antibiotic and extracellular protein production by Myxococcus coralloides D. Appl Microbiol Biotechnol 1990; 33:78-80. [PMID: 1367446 DOI: 10.1007/bf00170575] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
The effect of inorganic phosphate concentrations on antibiotic and extracellular protein production by Myxococcus coralloides D have been examined. Antibiotic production by growing cells of this myxobacterium was maximal at phosphate concentrations of 10-20 mM, but was inhibited by concentrations higher than 20 mM. The total extracellular protein and the extracellular protein per cell ratio were independent of phosphate levels in the culture broth.
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Affiliation(s)
- F Gonzalez
- Departamento de Microbiologia, Facultad de Ciencias, Universidad de Granada, Spain
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Abstract
Acid and alkaline phosphatase of Myxococcus coralloides were examined during vegetative growth in a liquid medium. Two extracellular phosphatases and two cell-bound phosphatases, acid and alkaline in both cases, were produced. The phosphatase production was unaltered by the presence of high concentrations of inorganic phosphate. Both enzymes were produced constitutively. These two hydrolases were released into the growth medium during the exponential growth phase (approximately 10% of total activity). The production of these enzymes was modified by the presence of organic acids and metal ions in the medium.
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Affiliation(s)
- F González
- Departmento de Microbiologia, Facultad de Ciencias, Unversidad de Granada, Spain
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Arias JM, Alonso CE, Lozano M. Test of the proton-neutron interacting boson-fermion model in the region around A=190. Phys Rev C Nucl Phys 1986; 33:1482-1495. [PMID: 9953300 DOI: 10.1103/physrevc.33.1482] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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Abstract
Myxococcus coralloides D was found to produce a substance with a narrow range of antibacterial activity. This substance was produced during the exponential growth phase and was not inducible by ultraviolet light or mitomycin C treatment. The bacteriocin was precipitable by ammonium sulphate, and showed resistance to heat (100 degrees C for 10 min), trypsin, lysozyme, beta-glucuronidase, DNase, RNase, acetone, ethyl ether, urea and mercaptoethanol; it was partially destroyed by pronase and inactivated at extreme pH values. Electron microscopy did not reveal any phage-like particles associated with bacteriocin activity.
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Abstract
A strain of Myxococcus coralloides producing an antibiotic capable of inhibiting growth of Gram-positive bacteria was isolated. Antibiotic production occurred during vegetative growth but not during myxospore formation. The antibiotic was extracted from the growth medium with chloroform and purified by adsorption on silicic acid and by preparative silica gel thin-layer chromatography. The purified antibiotic showed a resistance to heat, acid, alkali and proteolytic enzymes. Chromatographic and electrophoretic behavior as well as infrared, ultraviolet and mass spectra are presented.
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