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2.
Peptides ; 166: 171037, 2023 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-37301481

RESUMO

Prolactin (PRL) is a polypeptide hormone that has been reported to play a significant role in neuroprotection against neuronal excitotoxicity produced by glutamate (Glu) or kainic acid (KA) in both, in vitro and in vivo models. However, the molecular mechanisms involved in PRL's neuroprotective effects in the hippocampus have not been completely elucidated. The aim of the present study was to assess the signaling pathways involved in PRL neuroprotection against excitotoxicity. Primary rat hippocampal neuronal cell cultures were used to assess PRL-induced signaling pathway activation. The effects of PRL on neuronal viability, as well as its effects on activation of key regulatory pathways, phosphoinositide 3-kinases/Protein Kinase B (PI3K/AKT) and glycogen synthase kinase 3ß / nuclear factor kappa B (GSK3ß/NF-κB), were evaluated under conditions of Glutamate-induced excitotoxicity. Additionally, the effect on downstream regulated genes such as Bcl-2 and Nrf2, was assessed. Here, we show that the PI3K/AKT signaling pathway is activated by PRL treatment during excitotoxicity, promoting neuronal survival through upregulation of active AKT and GSK3ß/NF-κB, resulting in induction of Bcl-2 and Nrf2 gene expression. Inhibition of the PI3K/AKT signaling pathway abrogated the protective effect of PRL against Glu-induced neuronal death. Overall, results indicate that the neuroprotective actions of PRL are mediated in part, by the activation of the AKT pathway and survival genes. Our data support the idea that PRL could be useful as a potential neuroprotective agent in different neurological and neurodegenerative diseases.


Assuntos
NF-kappa B , Fármacos Neuroprotetores , Ratos , Animais , NF-kappa B/metabolismo , Proteínas Proto-Oncogênicas c-akt/metabolismo , Neuroproteção , Prolactina/farmacologia , Prolactina/metabolismo , Fosfatidilinositol 3-Quinases/metabolismo , Glicogênio Sintase Quinase 3 beta/metabolismo , Fator 2 Relacionado a NF-E2/metabolismo , Hipocampo/metabolismo , Fármacos Neuroprotetores/farmacologia , Neurônios/metabolismo , Ácido Glutâmico/toxicidade , Ácido Glutâmico/metabolismo
3.
Neurosci Lett ; 810: 137344, 2023 07 27.
Artigo em Inglês | MEDLINE | ID: mdl-37315731

RESUMO

The aim of this study was to determine the effect of prolactin (PRL) on intracellular calcium (Ca2+) concentration and its neuroprotective role in a model of kainic acid (KA) excitotoxicity in primary cultures of hippocampal neurons. Cell viability and intracellular Ca2+ concentrations were determined by MTT and Fura-2 assays, respectively, either after induction by KA as an agonist or after treatment with NBQX antagonist alone or in combination with PRL administration. Expression of ionotropic glutamatergic receptors (iGluRs) subunits in neuronal cells was determined by RT-qPCR. Dose-response treatments with KA or glutamate (Glu), the latter used as endogenous agonist control, induced a significant increase in neuronal intracellular Ca2+ concentration followed by a significant decrease in hippocampal neuronal viability. Administration of PRL induced a significant increase in neuronal viability after treatment with KA. Furthermore, administration of PRL decreased intracellular Ca2+ concentrations induced by KA treatment. Independent administration of the AMPAR-KAR antagonist reversed cell death and reduced intracellular Ca2+ concentration in a similar manner as PRL. Additionally, mRNA expression of AMPAR, KAR and NMDAR subtypes were detected in hippocampal neurons; however, no significant changes in iGluRs subunit expression were observed due to excitotoxicity or PRL treatment. The results suggest that PRL inhibits the increase in intracellular Ca2+ concentration induced by KA, leading to neuroprotection.


Assuntos
Ácido Caínico , Prolactina , Prolactina/farmacologia , Ácido Caínico/toxicidade , Neuroproteção , Hipocampo/metabolismo , Neurônios/metabolismo
5.
Radiat Environ Biophys ; 61(3): 407-423, 2022 08.
Artigo em Inglês | MEDLINE | ID: mdl-35819511

RESUMO

The clinical information on the relationship between the cardiac contact distance (CCD), the maximum dose (Dmax) delivered to the left anterior descending (LAD) coronary artery and the mean heart dose has mostly focused on patients with breast-conserving surgery (BCS), being scarce in postmastectomy patients. The aim of this study is to determine the association between the CCD and the Dmax delivered to the LAD. The secondary objective was to evaluate the dosimetric results of comparing three-dimensional conformal radiotherapy (3D-CRT) to intensity-modulated radiotherapy (IMRT) and volumetric modulated arc therapy (VMAT) techniques for post mastectomized breast cancer patients with irradiation to the left chest wall. 53 cases of women who received adjuvant standard fractionated postmastectomy radiotherapy (PMRT) were used. Three types of plans were created for each patient: 3D-CRT, seven equidistant IMRT fields, and four partial VMAT arcs. Correlations were evaluated using Pearson's correlation coefficient. Plans made with IMRT and VMAT showed improved homogeneity and conformity. Associations between CCD and Dmax to LAD were positive for all three plan types. Compared to 3D-CRT, the modulated intensity plans obtained better dose homogeneity and conformity to the target volume. The LAD and heart doses were significantly lower for IMRT and VMAT plans. The CCD can be used as a predictor of the maximum and mean doses of the LAD. Modulated intensity techniques allow for better dose distribution and dose reduction to the heart and LAD.


Assuntos
Neoplasias da Mama , Radioterapia de Intensidade Modulada , Neoplasias da Mama/radioterapia , Vasos Coronários , Feminino , Humanos , Mastectomia , Órgãos em Risco/efeitos da radiação , Dosagem Radioterapêutica , Planejamento da Radioterapia Assistida por Computador
6.
Methods Mol Biol ; 2412: 471-479, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-34918263

RESUMO

Epitope-based vaccines is one of the most recent methodologies applied in bioinformatics studies. This strategy consists of identifying regions of the protein (peptides or epitopes) which show antigen properties capable of stimulating the immune system against proteins from virus, bacteria, fungi, etc. This chapter describes a general procedure to identify epitopes to be used as epitope vaccine using bioinformatics methods including primary protein sequence analyses, epitope predictor, docking, and molecular dynamics simulations for the selection of T- and B-cell epitopes.


Assuntos
Biologia Computacional , Vacinas , Epitopos de Linfócito B , Epitopos de Linfócito T , Simulação de Dinâmica Molecular , Vacinas de Subunidades Antigênicas
7.
Front Neuroendocrinol ; 61: 100913, 2021 04.
Artigo em Inglês | MEDLINE | ID: mdl-33766566

RESUMO

It has been well recognized that prolactin (PRL), a pleiotropic hormone, has many functions in the brain, such as maternal behavior, neurogenesis, and neuronal plasticity, among others. Recently, it has been reported to have a significant role in neuroprotection against excitotoxicity. Glutamate excitotoxicity is a common alteration in many neurological and neurodegenerative diseases, leading to neuronal death. In this sense, several efforts have been made to decrease the progression of these pathologies. Despite various reports of PRL's neuroprotective effect against excitotoxicity, the signaling pathways that underlie this mechanism remain unclear. This review aims to describe the most recent and relevant studies on the molecular signaling pathways, particularly, PI3K/AKT, NF-κB, and JAK2/STAT5, which are currently under investigation and might be implicated in the molecular mechanisms that explain the PRL effects against excitotoxicity and neuroprotection. Remarkable neuroprotective effects of PRL might be useful in the treatment of some neurological diseases.


Assuntos
Neuroproteção , Fármacos Neuroprotetores , Feminino , Hipocampo , Humanos , Fármacos Neuroprotetores/farmacologia , Fosfatidilinositol 3-Quinases/farmacologia , Prolactina
8.
Neuroscience ; 461: 180-193, 2021 05 01.
Artigo em Inglês | MEDLINE | ID: mdl-33647379

RESUMO

Glutamate (Glu) is known as the main excitatory neurotransmitter in the central nervous system. It can trigger a series of processes ranging from synaptic plasticity to neurophysiological regulation. To carry out its functions, Glu acts via interaction with its cognate receptors, which are ligand-dependent. Glutamatergic receptors include ionotropic and metabotropic categories. The first allows the passage of ions through the postsynaptic membrane, while the metabotropic subtype activates signaling cascades through second messengers. It is well known that an excess of extracellular Glu concentration induces overstimulation of ionotropic glutamatergic receptors (iGluRs), causing the excitotoxicity phenomenon that leads to neuronal damage and cell death. Excitotoxicity plays a crucial role in different brain pathologies such as brain strokes, epilepsy and neurodegenerative disorders. However, until now, there are no effective neuroprotective compounds to prevent or rescue neurons from excitotoxicity. Thus, the continuous elucidation of the molecular mechanisms underlying excitotoxicity in order to prevent damage or neuronal death is necessary. Therefore, the aim of this review was to summarize the current knowledge regarding iGluRs, while describing their structures and molecular mechanisms of action, including their role in excitotoxicity, as well as the current strategies to reduce excitotoxic damage. Particularly, strategies mediated by prolactin, a somatotropin family-related hormone that displays a significant neuroprotective effect against both Glu and kainic acid-induced excitotoxicity in the hippocampus, are described. Finally, the role of prolactin as a possible molecule in the treatment of excitotoxicity in neurological diseases is discussed.


Assuntos
Fármacos Neuroprotetores , Prolactina , Ácido Glutâmico/toxicidade , Neurônios , Neuroproteção , Fármacos Neuroprotetores/farmacologia , Receptores de Neurotransmissores
9.
Br J Dermatol ; 185(1): 164-176, 2021 07.
Artigo em Inglês | MEDLINE | ID: mdl-33400270

RESUMO

BACKGROUND: Hidradenitis suppurativa (HS) is a chronic inflammatory disease, characterized by painful, purulent and destructive skin alterations in intertriginous areas. OBJECTIVES: We investigated the expression and role in HS of granulocyte colony-stimulating factor (G-CSF), the regulator of neutrophil biology, as clinical signs of a neutrophilic granulocyte-driven inflammation are distinctive in the disease. METHODS: Skin and blood samples obtained from different cohorts of patients with HS and control individuals were assessed by RNA sequencing, quantitative polymerase chain reaction on reverse transcribed mRNA, and/or enzyme-linked immunosorbent assay. Mechanistic studies using keratinocytes, dermal fibroblasts, immune cell populations and skin biopsies were performed. RESULTS: G-CSF was abundant in HS skin, particularly in inflamed nodules and abscesses. Its levels even exceeded those found in other inflammatory skin diseases. Interleukin (IL)-1 and IL-17, respectively, induced G-CSF production by fibroblasts and keratinocytes. These effects were enhanced by tumour necrosis factor (TNF)-α and IL-36. Accordingly, fibroblasts separated from HS lesions expressed G-CSF, and IL-1 receptor antagonist reduced G-CSF levels in explanted HS skin. G-CSF blood levels positively correlated with severity of HS. Elevated lesional G-CSF receptor levels were linked to upregulation of molecules that contribute to prolonged activation of neutrophils by components of bacteria and damaged host cells [formyl peptide receptor 1 (FPR1), FPR2 and free fatty acid receptor 2 (FFAR2)], neutrophil survival [TNF receptor superfamily member 10C (TNFRSF10C/TRAIL-R3) and TNF receptor superfamily member 6B], kinases (tyrosine-protein kinase HCK and hexokinase 3), and skin destruction [MMP25 (matrix metalloproteinase 25) and ADAM8 (disintegrin and metalloproteinase domain-containing protein 8)]. G-CSF elevated the expression of FPR1, FFAR2, and TNFRSF10C/TRAIL-R3 in neutrophils and synergized with bacterial components to induce skin-destructive enzymes. CONCLUSIONS: The G-CSF pathway engages both tissue and immune cells, is strongly activated in HS lesions, and offers the opportunity to target the neutrophil-driven inflammation.


Assuntos
Hidradenite Supurativa , Proteínas ADAM , Fator Estimulador de Colônias de Granulócitos , Humanos , Queratinócitos , Proteínas de Membrana , Neutrófilos , Pele , Fator de Necrose Tumoral alfa
10.
Arch Virol ; 165(4): 891-911, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32060794

RESUMO

Pandemics caused by influenza A virus (IAV) are responsible for the deaths of millions of humans around the world. One of these pandemics occurred in Mexico in 2009. Despite the impact of IAV on human health, there is no effective vaccine. Gene mutations and translocation of genome segments of different IAV subtypes infecting a single host cell make the development of a universal vaccine difficult. The design of immunogenic peptides using bioinformatics tools could be an interesting strategy to increase the success of vaccines. In this work, we used the predicted amino acid sequences of the neuraminidase (NA) and hemagglutinin (HA) proteins of different IAV subtypes to perform multiple alignments, epitope predictions, molecular dynamics simulations, and experimental validation. Peptide selection was based on the following criteria: promiscuity, protein surface exposure, and the degree of conservation among different medically relevant IAV strains. These peptides were tested using immunological assays to test their ability to induce production of antibodies against IAV. We immunized rabbits and mice and measured the levels of IgG and IgA antibodies in serum samples and nasal washes. Rabbit antibodies against the peptides P11 and P14 (both of which are hybrids of NA and HA) recognized HA from both group 1 (H1, H2, and H5) and group 2 (H3 and H7) IAV and also recognized the purified NA protein from the viral stock (influenza A Puerto Rico/916/34). IgG antibodies from rabbits immunized with P11 and P14 were capable of recognizing viral particles and inhibited virus hemagglutination. Additionally, intranasal immunization of mice with P11 and P14 induced specific IgG and IgA antibodies in serum and nasal mucosa, respectively. Interestingly, the IgG antibodies were found to have neutralizing capability. In conclusion, the peptides designed through in silico studies were validated in experimental assays.


Assuntos
Anticorpos Neutralizantes/imunologia , Anticorpos Antivirais/imunologia , Vírus da Influenza A/imunologia , Vacinas contra Influenza/imunologia , Influenza Humana/prevenção & controle , Sequência de Aminoácidos , Animais , Biologia Computacional , Epitopos/química , Epitopos/genética , Epitopos/imunologia , Glicoproteínas de Hemaglutininação de Vírus da Influenza/química , Glicoproteínas de Hemaglutininação de Vírus da Influenza/genética , Glicoproteínas de Hemaglutininação de Vírus da Influenza/imunologia , Humanos , Imunização , Vírus da Influenza A/química , Vírus da Influenza A/genética , Vacinas contra Influenza/química , Vacinas contra Influenza/genética , Influenza Humana/imunologia , Influenza Humana/virologia , Camundongos , Camundongos Endogâmicos BALB C , Neuraminidase/química , Neuraminidase/genética , Neuraminidase/imunologia , Coelhos , Alinhamento de Sequência , Proteínas Virais/química , Proteínas Virais/genética , Proteínas Virais/imunologia
11.
Mol Cell Endocrinol ; 473: 17-30, 2018 09 15.
Artigo em Inglês | MEDLINE | ID: mdl-29275169

RESUMO

Asthma symptoms have been associated with sex steroids. During childhood, this illness seems more frequent in boys than in girls and this tendency reverts in puberty when it is more severe in women. Testosterone (TES), at supraphysiological concentrations, relaxed pre-contracted airway smooth muscle, but its effects at physiological concentrations have not been thoroughly studied. We explored this possibility in guinea pig tracheal smooth muscle. In myocytes TES (10 nM) abolished carbachol (CCh)-induced intracellular Ca2+ concentration ([Ca2+]i) increment. Ca2+ responses to ATP were partially modified by TES while histamine's were not. These results indicate that inositol 1,4,5-trisphosphate (IP3) signaling pathway might be involved. Photolysis of caged-IP3 increased [Ca2+]i and TES abolished this effect. TES diminished reactivity of the smooth muscle to CCh and this effect was non-genomic since it was unchanged by flutamide. In tracheal smooth muscle, mRNA for each IP3 receptor (ITPR) isoform was found and, by immunofluorescence, ITPR1 and ITPR3 seems to be the main isoforms observed while ITPR2 was less prominent. Comparing the amino acid sequence of ITPR1 and the sequence of the TES binding site on the androgen receptor, we found that they share a short sequence. This domain could be responsible for the TES binding to the ITPR1 and probably for its blocking effect. We conclude that TES modifies ITPR1 function in airway smooth muscle, turning this tissue less reactive to contractile agonists that act through PLCß-IP3 signaling cascade. These results might be related to the low asthma prevalence in males from puberty to adulthood.


Assuntos
Receptores de Inositol 1,4,5-Trifosfato/metabolismo , Músculo Liso/fisiologia , Testosterona/farmacologia , Traqueia/fisiologia , Sequência de Aminoácidos , Animais , Cálcio/metabolismo , Canais de Cálcio/metabolismo , Carbacol/farmacologia , Genoma , Cobaias , Histamina/farmacologia , Humanos , Inositol 1,4,5-Trifosfato/farmacologia , Receptores de Inositol 1,4,5-Trifosfato/química , Espaço Intracelular/metabolismo , Masculino , Contração Muscular/efeitos dos fármacos , Músculo Liso/efeitos dos fármacos , Miócitos de Músculo Liso/efeitos dos fármacos , Miócitos de Músculo Liso/metabolismo , Isoformas de Proteínas/metabolismo , Receptores Androgênicos/química , Receptores Androgênicos/metabolismo , Transdução de Sinais/efeitos dos fármacos , Traqueia/efeitos dos fármacos
12.
Rev. méd. Chile ; 145(11): 1480-1484, nov. 2017. graf
Artigo em Espanhol | LILACS | ID: biblio-902469

RESUMO

Austrian syndrome is a triad characterized by pneumonia, meningitis and endocarditis, as a result of a Streptococcus pneumoniae bacteremia. We report a previously healthy 49 year-old male, who consulted at the emergency care unit with a history of one week of pleuritic pain, fever leading to an altered level of consciousness and seizures. A diagnosis of community-acquired pneumonia and meningitis was reached, isolating Streptococcus pneumoniae in the cerebrospinal fluid and blood cultures. Antibiotic treatment was started but the patient had an unsatisfactory response. During hospitalization a new heart murmur was found in the physical examination. An echocardiography was performed and a massive aortic valve insufficiency was found along with vegetations and a perforation of the same valve. The valve was replaced by a prosthetic one and the patient responded satisfactorily to the surgical and antibiotic treatment, without complications.


Assuntos
Humanos , Masculino , Pessoa de Meia-Idade , Pneumonia Pneumocócica/microbiologia , Streptococcus pneumoniae/isolamento & purificação , Meningites Bacterianas/microbiologia , Endocardite Bacteriana/microbiologia , Pneumonia Pneumocócica/cirurgia , Pneumonia Pneumocócica/diagnóstico por imagem , Síndrome , Tomografia Computadorizada por Raios X , Meningites Bacterianas/cirurgia , Meningites Bacterianas/diagnóstico por imagem , Endocardite Bacteriana/cirurgia , Endocardite Bacteriana/diagnóstico por imagem
13.
Rev. méd. Chile ; 145(10): 1353-1358, oct. 2017. tab, graf
Artigo em Espanhol | LILACS | ID: biblio-902451

RESUMO

Marantic or nonbacterial thrombotic endocarditis is characterized for the presence of vegetations formed by a meshwork of fibrin and other cellular material similar a blood clot, without the presence of microorganisms. It is often related with tumors and chronic inflammatory states. We report a 49 years old female with a history of weight loss and asthenia, presenting with multiple cerebrovascular attacks and fever. Blood cultures were negative and the fever did not subside with antibiotic treatment. Trans esophageal echocardiogram showed a mitral valve vegetation and thickening of the free edge of both leaflets. In search of the etiology of such a case, a primary pancreatic cancer with distant metastases was found. We cannot rule out the differential diagnosis with bacterial endocarditis with negative blood cultures, although the clinical context supports a non-infectious etiology.


Assuntos
Humanos , Feminino , Pessoa de Meia-Idade , Endocardite não Infecciosa/patologia , Endocardite não Infecciosa/diagnóstico por imagem , Neoplasias Pancreáticas/diagnóstico por imagem , Imageamento por Ressonância Magnética , Radiografia Torácica , Tomografia Computadorizada por Raios X , Evolução Fatal , Acidente Vascular Cerebral/diagnóstico por imagem , Diagnóstico Diferencial
15.
Rev Med Chil ; 145(10): 1353-1358, 2017 Oct.
Artigo em Espanhol | MEDLINE | ID: mdl-29488578

RESUMO

Marantic or nonbacterial thrombotic endocarditis is characterized for the presence of vegetations formed by a meshwork of fibrin and other cellular material similar a blood clot, without the presence of microorganisms. It is often related with tumors and chronic inflammatory states. We report a 49 years old female with a history of weight loss and asthenia, presenting with multiple cerebrovascular attacks and fever. Blood cultures were negative and the fever did not subside with antibiotic treatment. Trans esophageal echocardiogram showed a mitral valve vegetation and thickening of the free edge of both leaflets. In search of the etiology of such a case, a primary pancreatic cancer with distant metastases was found. We cannot rule out the differential diagnosis with bacterial endocarditis with negative blood cultures, although the clinical context supports a non-infectious etiology.


Assuntos
Endocardite não Infecciosa/diagnóstico por imagem , Endocardite não Infecciosa/patologia , Diagnóstico Diferencial , Evolução Fatal , Feminino , Humanos , Imageamento por Ressonância Magnética , Pessoa de Meia-Idade , Neoplasias Pancreáticas/diagnóstico por imagem , Radiografia Torácica , Acidente Vascular Cerebral/diagnóstico por imagem , Tomografia Computadorizada por Raios X
16.
Biochemistry ; 54(33): 5235-41, 2015 Aug 25.
Artigo em Inglês | MEDLINE | ID: mdl-26250140

RESUMO

The calcium pump [sarcoplasmic reticulum (SR) Ca(2+)-ATPase (SERCA)] transports Ca(2+) from the cytosol to the SR lumen at the expense of ATP hydrolysis and proton countertransport, thus playing a central role in Ca(2+) homeostasis and muscle contractility. Proton countertransport via deprotonation of transport site residue Glu309 is a critical first step in SERCA activation because it accelerates the E2-E1 structural transition. Previous studies have suggested that flipping of Glu309 toward the cytosol constitutes the primary mechanism for Glu309 deprotonation, but no conclusive data to support this hypothesis have been published. Therefore, we performed three independent 1 µs molecular dynamics simulations of the E2 state protonated at transport site residues Glu309, Glu771, and Glu908. Structural analysis and pKa calculations showed that Glu309 deprotonation occurs by an inward-to-outward side-chain transition. We also found that Glu309 deprotonation and proton countertransport occur through transient (~113 ps) water wires connecting Glu309 with the cytosol. Although both mechanisms are operational, we found that transient water wire formation, and not Glu309 flipping, is the primary mechanism for Glu309 deprotonation and translocation of protons to the cytosol. The outward-to-inward transition of protonated Glu309 and the presence of water wires suggest that protons from the cytosol might be passively transported to the lumen via Glu309. However, structural analysis indicates that passive SR proton leakage into the lumen unlikely occurs through Glu309 in the E2 state. These findings provide a time-resolved visualization of the first step in the molecular mechanism of SERCA activation and proton transport across the SR.


Assuntos
Simulação de Dinâmica Molecular , Prótons , ATPases Transportadoras de Cálcio do Retículo Sarcoplasmático/química , ATPases Transportadoras de Cálcio do Retículo Sarcoplasmático/metabolismo , Transporte Biológico , Cálcio/metabolismo , Ativação Enzimática , Estabilidade Enzimática , Conformação Proteica , Água/química
17.
J Am Chem Soc ; 137(22): 7055-8, 2015 Jun 10.
Artigo em Inglês | MEDLINE | ID: mdl-26028459

RESUMO

The calcium pump sarcoplasmic reticulum Ca(2+)-ATPase (SERCA) counter-transports Ca(2+) and H(+) at the expense of ATP hydrolysis. SERCA uses separate proton and metal ion pathways during active transport to neutralize the highly charged transport site, thus preserving SERCA's structural stability during active Ca(2+) transport. Although separate metal ion and proton pathways have been identified during slow (millisecond) structural transitions of SERCA, the existence of simultaneous metal and proton pathways during fast (microsecond) structural transitions remains unknown. We have analyzed microsecond-long trajectories of E1·H(+)771, a protonated intermediate of the pump populated during SERCA regulation. We found a transiently established hydrophobic pore in the luminal side of the transmembrane helices 6, 8, and 9. This narrow (0.5-0.6 nm) pore connects the transport sites to the sarcoplasmic reticulum lumen through a chain of water molecules. Protein pKa calculations of the transport site residues and structural analysis of the water molecules showed that this pore is suitable for proton transport. This transient proton pathway ensures neutralization of the transport sites during the rapid structural transitions associated with regulation of the pump. We conclude that this transient proton pathway plays a central role in optimizing active Ca(2+) transport by SERCA. Our discovery provides insight into ion-exchange mechanisms through transient hydrophobic pores in P-type ATPases.


Assuntos
Modelos Químicos , Prótons , ATPases Transportadoras de Cálcio do Retículo Sarcoplasmático/metabolismo , Cristalografia , ATPases Transportadoras de Cálcio do Retículo Sarcoplasmático/química
18.
Biophys J ; 108(7): 1697-1708, 2015 Apr 07.
Artigo em Inglês | MEDLINE | ID: mdl-25863061

RESUMO

We performed protein pKa calculations and molecular dynamics (MD) simulations of the calcium pump (sarcoplasmic reticulum Ca(2+)-ATPase (SERCA)) in complex with phospholamban (PLB). X-ray crystallography studies have suggested that PLB locks SERCA in a low-Ca(2+)-affinity E2 state that is incompatible with metal-ion binding, thereby blocking the conversion toward a high-Ca(2+)-affinity E1 state. Estimation of pKa values of the acidic residues in the transport sites indicates that at normal intracellular pH (7.1-7.2), PLB-bound SERCA populates an E1 state that is deprotonated at residues E309 and D800 yet protonated at residue E771. We performed three independent microsecond-long MD simulations to evaluate the structural dynamics of SERCA-PLB in a solution containing 100 mM K(+) and 3 mM Mg(2+). Principal component analysis showed that PLB-bound SERCA lies exclusively along the structural ensemble of the E1 state. We found that the transport sites of PLB-bound SERCA are completely exposed to the cytosol and that K(+) ions bind transiently (≤5 ns) and nonspecifically (nine different positions) to the two transport sites, with a total occupancy time of K(+) in the transport sites of 80%. We propose that PLB binding to SERCA populates a novel (to our knowledge) E1 intermediate, E1⋅H(+)771. This intermediate serves as a kinetic trap that controls headpiece dynamics and depresses the structural transitions necessary for Ca(2+)-dependent activation of SERCA. We conclude that PLB-mediated regulation of SERCA activity in the heart results from biochemical and structural transitions that occur primarily in the E1 state of the pump.


Assuntos
Proteínas de Ligação ao Cálcio/química , Simulação de Dinâmica Molecular , ATPases Transportadoras de Cálcio do Retículo Sarcoplasmático/química , Sequência de Aminoácidos , Animais , Sítios de Ligação , Cálcio/metabolismo , Proteínas de Ligação ao Cálcio/metabolismo , Dados de Sequência Molecular , Potássio/metabolismo , Ligação Proteica , Coelhos , ATPases Transportadoras de Cálcio do Retículo Sarcoplasmático/metabolismo
19.
Rev. colomb. gastroenterol ; 29(4): 446-448, oct.-dic. 2014. ilus
Artigo em Espanhol | LILACS | ID: lil-742637

RESUMO

Informamos el caso de un hombre inmunocompetente que consultó por cuadro de sangrado digestivo alto secundario a una úlcera esofágica de origen tuberculoso. El compromiso gastrointestinal por el Mycobacterium tuberculosis es raro aun en pacientes con altas prevalencias de enfermedad pulmonar y extrapulmonar; los sitios de mayor afectación son íleon terminal y el peritoneo, la enfermedad esofágica es exótica y generalmente es secundaria a la extensión proveniente de órganos vecinos infectados, como ganglios mediastinales y/o bronquios. La clínica, las imágenes endoscópicas y radiológicas de la enfermedad esofágica suele simular una neoplasia maligna. La quimioterapia antituberculosa es la base del tratamiento, rara vez se requiere manejo quirúrgico.


We report the case of an immune-competent man with symptoms of upper gastrointestinal bleeding secondary to esophageal ulcers of tubercular origin. Gastrointestinal involvement from Mycobacterium tuberculosis is rare even in patients with numerous occurrences of pulmonary and extrapulmonary diseases. The most frequently affected sites are the terminal ileum and the peritoneum. Esophageal tuberculosis is exotic and is usually secondary to extension from neighboring infected organs such as the mediastinal nodes and/or the bronchi. Clinical, endoscopic and radiological pictures of the esophageal disease often mimic malignancy. Tuberculosis treatment is the mainstay of treatment, and surgery is rarely required.


Assuntos
Humanos , Masculino , Idoso de 80 Anos ou mais , Esôfago , Hemorragia Gastrointestinal , Tuberculose , Úlcera
20.
Clín. investig. ginecol. obstet. (Ed. impr.) ; 41(4): 146-150, oct.-dic. 2014. ilus, tab
Artigo em Espanhol | IBECS | ID: ibc-128904

RESUMO

Evaluar la utilidad de un separador semiautomático durante intervenciones ginecobstétricas. Material y métodos El estudio fue abierto, prospectivo, longitudinal y exploratorio, el separador fue evaluado en intervenciones quirúrgicas. Muestra: 100 pacientes; 45 con antecedentes de cesárea, 49 pacientes con obesidad, 36 con sobrepeso, 10 normales. Intervenciones quirúrgicas realizadas: 82 por vía abdominal, 18 por vía vaginal. Médicos participantes: 14 especialistas en ginecobstetricia, 86 médicos residentes. Análisis estadístico: se utilizó el programa SPSS. Resultados La articulación, desarticulación, colocación y extracción del separador fue satisfactoria en 98 intervenciones. Hubo un caso de inestabilidad y otro donde la amplitud fue insuficiente. Las intervenciones vaginales requirieron un solo cirujano. Hubo reducción en el tiempo de duración de la cirugía, en la pérdida de sangre, menor cantidad de anestesia y material de curación. Conclusión El separador Soriano fue útil en el 98% de los casos lo que mejoró la calidad y tiempo de las intervenciones quirúrgicas


To evaluate the usefulness of automatic surgical retractor in obstetric and gynecological interventions. Material and methods Open, prospective, longitudinal, exploratory study to evaluate the retractor in surgical interventions.Sample100 patients: 45 patients with previous cesarean sections, 49 patients classified as obese, 36 who were overweight, and 10 with normal weight. Surgical interventions: 82 abdominal, 18 vaginal. Participating physicians14 obstetric and gynecological surgeons, and 86 residents in gynecology and obstetric. Statistical analysis Was used the SPSS program. Results Articulation, disarticulation, collocation and retraction of the retractor was satisfactory in 98 interventions. There was one case of instability, and another of insufficient width. Vaginal interventions required only one operator. The instrument reduced the duration of surgery, blood loss, and the use of anesthetics and other material. Conclusion The Soriano surgical retractor was useful in 98% of the patients and improved the quality and time of the surgical interventions


Assuntos
Humanos , Feminino , Obesidade Mórbida/cirurgia , Procedimentos Cirúrgicos em Ginecologia/métodos , Instrumentos Cirúrgicos , Abdome/cirurgia , Estudos Prospectivos , Duração da Cirurgia , Complicações Pós-Operatórias
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