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1.
Actas Dermosifiliogr ; 114(7): 580-586, 2023.
Artigo em Inglês, Espanhol | MEDLINE | ID: mdl-37088287

RESUMO

BACKGROUND AND OBJECTIVE: SARS-CoV-2 is more easily spread by close contact, which is inherent to sexual intercourse. People with, or at risk for, sexually transmitted infections (STIs) may therefore have higher rates of COVID-19. The aim of this study was to estimate SARS-CoV-2 antibody seroprevalence in people seen at a dedicated STI clinic, compare our findings to the estimated seroprevalence in the local general population, and study factors associated with SARS-CoV-2 infection in this setting. MATERIAL AND METHODS: Cross-sectional observational study including consecutive patients older than 18 years of age who had not yet been vaccinated against COVID-19 and who underwent examination or screening at a dedicated municipal STI clinic in March and April 2021. We ordered rapid SARS-CoV-2 serology and collected information on demographic, social, and sexual variables, STI diagnoses, and history of symptoms compatible with SARS-CoV-2 infection. RESULTS: We studied 512 patients (37% women). Fourteen (24.2%) had a positive SARS-CoV-2 test. Variables associated with positivity were use of FFP2 masks (odds ratio 0.50) and a higher-than-average number of sexual partners (odds ratio 1.80). Use of FFP2 masks was not randomly distributed in this sample. CONCLUSIONS: Sexually active members of the population in this study had a higher incidence of SARS-CoV-2 infection than the general population. The main route of infection in this group appears to be respiratory, linked to close contact during sexual encounters; sexual transmission of the virus is probably limited.


Assuntos
COVID-19 , Saúde Sexual , Infecções Sexualmente Transmissíveis , Humanos , Feminino , Masculino , COVID-19/epidemiologia , SARS-CoV-2 , Incidência , Estudos Transversais , Estudos Soroepidemiológicos , Infecções Sexualmente Transmissíveis/epidemiologia , Infecções Sexualmente Transmissíveis/prevenção & controle
2.
Opt Lett ; 45(20): 5856-5859, 2020 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-33057302

RESUMO

We analyze the formation of localized structures in cavity-enhanced second-harmonic generation. We focus on the phase-matched limit, and consider that fundamental and generated waves have opposite signs of group velocity dispersion. We show that these states form due to the locking of domain walls connecting two stable homogeneous states of the system, and undergo collapsed snaking. We study the impact of temporal walk-off on the stability and dynamics of these localized states.

3.
Chaos ; 30(8): 083111, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32872794

RESUMO

A ring resonator made of a silica-based optical fiber is a paradigmatic system for the generation of dissipative localized structures or dissipative solitons. We analyze the effect of the non-instantaneous nonlinear response of the fused silica or the Raman response on the formation of localized structures. After reducing the generalized Lugiato-Lefever to a simple and generic bistable model with a nonlocal Raman effect, we investigate analytically the formation of moving temporal localized structures. This reduction is valid close to the nascent bistability regime, where the system undergoes a second-order critical point marking the onset of a hysteresis loop. The interaction between fronts allows for the stabilization of temporal localized structures. Without the Raman effect, moving temporal localized structures do not exist, as shown in M. G. Clerc, S. Coulibaly, and M. Tlidi, Phys. Rev. Res. 2, 013024 (2020). The detailed derivation of the speed and the width associated with these structures is presented. We characterize numerically in detail the bifurcation structure and stability associated with the moving temporal localized states. The numerical results of the governing equations are in close agreement with analytical predictions.

4.
Horm Behav ; 78: 43-51, 2016 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-26497248

RESUMO

Hydroelectrolytic imbalances, such as saline load (SL), trigger behavioral and neuroendocrine responses, such as thirst, hypophagia, vasopressin (AVP) and oxytocin (OT) release and hypothalamus­pituitary­adrenal (HPA) axis activation. To investigate the participation of the type-1 cannabinoid receptor (CB1R) in these homeostatic mechanisms,male adult Wistar rats were subjected to SL (0.3MNaCl) for four days. SL induced not only increases in the water intake and plasma levels of AVP, OT and corticosterone, as previously described, but also increases in CB1R expression in the lamina terminalis, which integrates sensory afferents, aswell as in the hypothalamus, the main integrative and effector area controlling hydroelectrolytic homeostasis. A more detailed analysis revealed that CB1R-positive terminals are in close apposition with not only axons but also dendrites and secretory granules of magnocellular neurons, particularly vasopressinergic cells. In satiated and euhydrated animals, the intracerebroventricular administration of the CB1R selective agonist ACEA (0.1 µg/5 µL) promoted hyperphagia, but this treatment did not reverse the hyperosmolality-induced hypophagia in the SL group. Furthermore, ACEA pretreatment potentiated water intake in the SL animals during rehydration as well as enhanced the corticosterone release and prevented the increase in AVP and OT secretion induced by SL. The same parameters were not changed by ACEA in the animals whose daily food intake was matched to that of the SL group (Pair-Fed). These data indicate that CB1Rs modulate the hydroelectrolytic balance independently of the food intake during sustained hyperosmolality and hypovolemia.


Assuntos
Metabolismo Energético/fisiologia , Receptor CB1 de Canabinoide/fisiologia , Cloreto de Sódio na Dieta/farmacologia , Equilíbrio Hidroeletrolítico , Animais , Ingestão de Alimentos/efeitos dos fármacos , Endocanabinoides/farmacologia , Metabolismo Energético/efeitos dos fármacos , Homeostase/efeitos dos fármacos , Homeostase/fisiologia , Sistema Hipotálamo-Hipofisário/efeitos dos fármacos , Sistema Hipotálamo-Hipofisário/metabolismo , Hipotálamo/efeitos dos fármacos , Hipotálamo/metabolismo , Hipovolemia/metabolismo , Masculino , Neurônios/efeitos dos fármacos , Neurônios/enzimologia , Neurônios/metabolismo , Sistema Hipófise-Suprarrenal/efeitos dos fármacos , Sistema Hipófise-Suprarrenal/metabolismo , Ratos , Ratos Wistar , Receptor CB1 de Canabinoide/agonistas , Equilíbrio Hidroeletrolítico/efeitos dos fármacos
5.
Genet Mol Res ; 14(4): 14479-87, 2015 Nov 19.
Artigo em Inglês | MEDLINE | ID: mdl-26600506

RESUMO

Leprosy is a highly infectious disease endemic to underdeveloped countries. In Maranhão State, Northeastern Brazil, the hyperendemic rate of 56.11 cases/100,000 inhabitants increased the necessity of better understanding the epidemiological profile of this population, particularly regarding efficient methods for evaluating individuals residing with diagnosed patients to understand disease transmission and the risk of infection. In this study, we examined the percentage of contacts with positive indices for Mycobacterium leprae DNA and phenol-glycolipid-1 antigen (PGL-1). PGL-1 was analyzed by an enzyme-linked immunosorbent assay, the ML-Flow test, and polymerase chain reaction of oral and nasal secretions of 808 leprosy contacts from Maranhão. PGL-1 was detected in 14.0% of patients and differed by operational classification of the index case (P < 0.05). Seropositive results of ML-Flow were 15.0% and identified individuals with and without Bacillus Calmette-Guérin vaccine scars. Molecular diagnosis detected M. leprae DNA in 5.6% of oral samples and 4.6% of nasal tissues, and 87% of subjects resided with high bacillary load patients. This study reinforces the efficacy of combining molecular and serological techniques to identify potential bacillus carriers in the asymptomatic stage of infection, such as in household contacts, highlighting the importance of these meth-ods for monitoring hyperendemic populations.


Assuntos
Antígenos de Bactérias/isolamento & purificação , Glicolipídeos/isolamento & purificação , Hanseníase/diagnóstico , Mycobacterium leprae/patogenicidade , Patologia Molecular/métodos , Adolescente , Adulto , Antígenos de Bactérias/imunologia , Vacina BCG , Brasil , Doenças Endêmicas , Características da Família , Feminino , Glicolipídeos/imunologia , Humanos , Hanseníase/epidemiologia , Hanseníase/imunologia , Masculino , Pessoa de Meia-Idade , Mycobacterium leprae/imunologia , Mycobacterium leprae/isolamento & purificação , Testes Sorológicos , Adulto Jovem
6.
Opt Express ; 22(25): 30943-54, 2014 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-25607043

RESUMO

In [Phys. Rev. Lett. 110, 064103 (2013)], using the Swift-Hohenberg equation, we introduced a mechanism that allows to generate oscillatory and excitable soliton dynamics. This mechanism was based on a competition between a pinning force at inhomogeneities and a pulling force due to drift. Here, we study the effect of such inhomogeneities and drift on temporal solitons and Kerr frequency combs in fiber cavities and microresonators, described by the Lugiato-Lefever equation with periodic boundary conditions. We demonstrate that for low values of the frequency detuning the competition between inhomogeneities and drift leads to similar dynamics at the defect location, confirming the generality of the mechanism. The intrinsic periodic nature of ring cavities and microresonators introduces, however, some interesting differences in the final global states. For higher values of the detuning we observe that the dynamics is no longer described by the same mechanism and it is considerably more complex.

7.
Int J Clin Pract ; 68(7): 820-9, 2014 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-25077290

RESUMO

AIMS: To validate a previously developed set of explicit criteria for the appropriateness of hospital admission among these patients using the RAND/UCLA Appropriateness Methodology (RAM). METHODS: We conducted a prospective cohort study of patients experiencing symptoms of COPD exacerbation seen in the emergency departments (ED) of 16 hospitals belonging to the Spanish National Health Service. Sociodemographic and clinical variables needed to assess appropriateness were recorded. Main outcomes were mortality, severe COPD evolution, complications at follow up, and three patient-reported measures: dyspnoea level, capacity for physical activity and perceived health status. RESULTS: Appropriately admitted patients were more likely to die (6.70% vs. 2.68%, p = 0.0102) than inappropriately admitted patients, and were more likely to develop severe evolution (27.09% vs. 6.08%, p < 0.0001) and complications (18.72% vs. 11.92%, p = 0.0244). Among discharged patients, no significant differences were observed in clinical outcomes. All patients exhibited worse dyspnoea and capacity for physical activity after exacerbation, but changes among appropriately admitted patients were less than among appropriately discharged patients. CONCLUSION: Our appropriateness criteria identified patients in worse condition at ED arrival who were more likely to benefit from admission in terms of mortality and COPD evolution.


Assuntos
Nível de Saúde , Hospitalização , Doença Pulmonar Obstrutiva Crônica/terapia , Idoso , Idoso de 80 Anos ou mais , Estudos de Coortes , Feminino , Humanos , Masculino , Estudos Prospectivos , Doença Pulmonar Obstrutiva Crônica/complicações , Doença Pulmonar Obstrutiva Crônica/mortalidade
8.
Artigo em Inglês | MEDLINE | ID: mdl-24171425

RESUMO

Performance of a bench-scale wastewater treatment plant, which consisted of a membrane bioreactor, was monitored daily using pure oxygen and air to supply aerobic conditions with the aim of studying the increases of the aeration and sludge removal efficiencies and the effect of the temperature. The results showed the capacity of membrane bioreactor systems for removing organic matter. The alpha-factors of the aeration were determined for six different MLSS concentrations in order to understand the system working when pure oxygen and air were used to supply aerobic conditions in the system. Aeration efficiency was increased between 30.7 and 45.9% when pure oxygen was used in the operation conditions (a hydraulic retention time of 12 h and MLSS concentrations between 4,018 and 11,192 mg/L). Sludge removal efficiency increased incrementally, from 0.2 to 1.5% when pure oxygen was used at low sludge retention time and from 1.5% to 15.4% at medium sludge retention time when temperature conditions were lower than 20°C. Moreover, the difference between calculated and experimental sludge retention time was lesser when pure oxygen was used to provide aerobic conditions, so the influence of the temperature decreased when the pure oxygen was used. These results showed the convenience of using pure oxygen due to the improvement in the performance of the system.


Assuntos
Ar , Reatores Biológicos/microbiologia , Oxigênio/metabolismo , Esgotos/microbiologia , Temperatura , Aerobiose , Tempo
9.
Phys Rev Lett ; 110(6): 064103, 2013 Feb 08.
Artigo em Inglês | MEDLINE | ID: mdl-23432247

RESUMO

We show that excitability is generic in systems displaying dissipative solitons when spatial inhomogeneities and drift are present. Thus, dissipative solitons in systems which do not have oscillatory states, such as the prototypical Swift-Hohenberg equation, display oscillations and type I and II excitability when adding inhomogeneities and drift to the system. This rich dynamical behavior arises from the interplay between the pinning to the inhomogeneity and the pulling of the drift. The scenario presented here provides a general theoretical understanding of oscillatory regimes of dissipative solitons reported in semiconductor microresonators. Our results open also the possibility to observe this phenomenon in a wide variety of physical systems.

10.
Radiologia (Engl Ed) ; 65(5): 447-457, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37758335

RESUMO

Image acquisition involves the use of static magnetic fields, field gradients and radiofrequency waves. These elements make the MRI a different modality. More and more centers work with 3.0 T equipment that present higher risks for the patient, compared to those of 1.5 T. Therefore, there is a need for updating for radiology staff that allows them to understand the risks and reduce them, since serious and even fatal incidents can occur. The objective of this work is to present a review and update of the risks to which patients are subjected during the performance of a magnetic resonance imaging (MRI) study.

11.
Acta Trop ; 242: 106909, 2023 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-37030489

RESUMO

Neglected bacterial zoonoses are a group of Neglected Tropical Diseases (NTDs) that are commonly underdiagnosed and underreported due to their undifferentiated febrile illness symptomology. Spotted fever group rickettsioses (SFGR), a subset of tick-borne bacterial zoonoses, belong in this group. There is a dichotomy in the reporting and recognition of these pathogens in Central America: countries with reduced human development scores-like El Salvador-have little to no research or surveillance dedicated to these pathogens and the diseases they cause. This was the third-ever tick survey in El Salvador, highlighting the knowledge gap in this country. A total of 253 ticks were collected from 11 animals at two farm sites and one veterinary office. Standard and quantitative PCR were used to detect presence of SFGR, Ehrlichia, and Anaplasma sp. pathogens in ticks. Ehrlichia sp. were detected in 2.4% of all collected ticks and Anaplasma sp. were detected in 5.5% of all ticks. Rickettsia rickettsii was amplified in 18.2% of ticks, and amplicons similar to R. parkeri, and R. felis were found in 0.8% and 0.4%, of collected ticks, respectively. This is the first report of these pathogenic bacterial species in El Salvador. This study emphasizes the need for further surveillance and research including incorporating additional human seroprevalence and testing to understand the public health burden in this country.


Assuntos
Rickettsia , Doenças Transmitidas por Carrapatos , Carrapatos , Animais , Humanos , Rickettsia/genética , Ehrlichia/genética , Carrapatos/microbiologia , Anaplasma/genética , Zoonoses Bacterianas , El Salvador , Estudos Soroepidemiológicos , Doenças Transmitidas por Carrapatos/epidemiologia
12.
Rev Neurol ; 75(9): 251-259, 2022 11 01.
Artigo em Espanhol | MEDLINE | ID: mdl-36285445

RESUMO

INTRODUCTION: Almost a third of all patients with epilepsy (30%) fail to respond to pharmacological treatment. The presence of single nucleotide polymorphisms (SNPs) in the individual may influence the variability of the response to drug treatment. The transporter hypothesis posits that the presence of SNPs in the genes encoding ABC proteins would affect the bioavailability of antiseizure drugs at the epileptogenic focus, giving rise to refractoriness. The aim of the present study was to evaluate the association of 13 polymorphisms in the ABCB1, ABCC2, ABCC5 and ABCG2 genes with drug-resistant epilepsy (DRE) in a Spanish population. SUBJECTS AND METHODS: A case-control study was conducted involving 327 patients with epilepsy: 227 resistant to drug therapy and 100 in whom their medication enabled them to control their symptoms, according to International League Against Epilepsy criteria. In the peripheral blood leukocyte DNA that was extracted, polymorphisms in the ABC transporter genes were studied. The iPlex® Gold and Mass ARRAY technology platform was used. The allele and genotypic frequencies of the case and control groups, p-value, odds ratio and 95% confidence intervals were compared. RESULTS: The allele and genotypic frequency of the present study was similar to that reported in population-based databases. For the SNPs studied, no significant differences (p > 0.05) were found in any of the inheritance models analysed. CONCLUSIONS: Our results suggest that there is no association between the polymorphisms analysed in the ABC genes and DRE in the Spanish population. Nevertheless, further studies will confirm or refute these results.


TITLE: Asociación entre los polimorfismos genéticos de nucleótido único en genes transportadores ABC con la epilepsia farmacorresistente en la población española.Introducción. El 30% de los pacientes con epilepsia no responde al tratamiento farmacológico. La presencia de polimorfismos genéticos de nucleótido único (SNP) en el individuo puede influir en la variabilidad de respuesta al tratamiento farmacológico. La hipótesis de transportadores plantea que la presencia de SNP en los genes que codifican las proteínas ABC repercutiría en la biodisponibilidad de los fármacos anticrisis en el foco epileptógeno, lo que ocasionaría refractariedad. El objetivo del presente estudio fue evaluar la asociación de 13 polimorfismos en los genes ABCB1, ABCC2, ABCC5 y ABCG2 con la epilepsia farmacorresistente (EFR) en población española. Sujetos y métodos. Se realizó un estudio de casos y controles que incluyó a 327 pacientes con epilepsia: 227 farmacorresistentes y 100 farmacocontrolados según los criterios de la Liga Internacional contra la Epilepsia. En el ADN de leucocitos de sangre periférica extraído se estudiaron los polimorfismos en los genes transportadores ABC. Se utilizó la plataforma tecnológica iPlex® Gold y Mass ARRAY. Se compararon las frecuencias alélicas y genotípicas del grupo de casos y del de controles, el valor de p, la odds ratio y los intervalos de confianza al 95%. Resultados. La frecuencia alélica y genotípica del presente estudio fue similar a la comunicada en las bases de datos poblacionales. En los SNP estudiados no se encontraron diferencias significativas (p > 0,05) en todos los modelos de herencia analizados. Conclusiones. Nuestros resultados sugieren que no existe asociación entre los polimorfismos analizados en los genes ABC con la EFR en población española. Sin embargo, otros estudios adicionales confirmarán o descartarán estos resultados.


Assuntos
Epilepsia Resistente a Medicamentos , Epilepsia , Humanos , Polimorfismo de Nucleotídeo Único , Transportadores de Cassetes de Ligação de ATP/genética , Estudos de Casos e Controles , Epilepsia Resistente a Medicamentos/tratamento farmacológico , Epilepsia Resistente a Medicamentos/genética , Epilepsia/tratamento farmacológico , Epilepsia/genética , Genótipo , Ouro/uso terapêutico , Nucleotídeos/uso terapêutico
13.
Cancer Lett ; 505: 24-36, 2021 05 01.
Artigo em Inglês | MEDLINE | ID: mdl-33617947

RESUMO

The NAD+-dependent deacetylase, Sirtuin 1 (SIRT1) is involved in prostate cancer pathogenesis. However, the actual contribution is unclear as some reports propose a protective role while others suggest it is harmful. We provide evidence for a contextual role for SIRT1 in prostate cancer. Our data show that (i) mice orthotopically implanted with SIRT1-silenced LNCaP cells produced smaller tumors; (ii) SIRT1 suppression mimicked AR inhibitory effects in hormone responsive LNCaP cells; and (iii) caused significant reduction in gene signatures associated with E2F and MYC targets in AR-null PC-3 and E2F and mTORC1 signaling in castrate-resistant ARv7 positive 22Rv1 cells. Our findings further show increased nuclear SIRT1 (nSIRT1) protein under androgen-depleted relative to androgen-replete conditions in prostate cancer cell lines. Silencing SIRT1 resulted in decreased recruitment of AR to PSA enhancer selectively under androgen-deprivation conditions. Prostate cancer outcome data show that patients with higher levels of nSIRT1 progress to advanced disease relative to patients with low nSIRT1 levels. Collectively, we demonstrate that lowering SIRT1 levels potentially provides new avenues to effectively prevent prostate cancer recurrence.


Assuntos
Neoplasias da Próstata/patologia , Receptores Androgênicos/fisiologia , Sirtuína 1/fisiologia , Idoso , Animais , Linhagem Celular Tumoral , Sobrevivência Celular , Progressão da Doença , Humanos , Masculino , Camundongos , Pessoa de Meia-Idade , Orquiectomia , Transdução de Sinais/fisiologia
14.
Animals (Basel) ; 11(2)2021 Feb 10.
Artigo em Inglês | MEDLINE | ID: mdl-33579035

RESUMO

The aim of this study was to evaluate the effect of carcass traits, lairage time and weather conditions during lairage and abattoir factors that impact the incidence of dark cutting in 142,228 grain-fed carcasses, as defined by Meat Standards Australia (MSA) guidelines. This study was conducted over a 12-month period analysing data from cattle that were supplied from seven feedlots and processed at three abattoirs. Abattoir data indicated that the average incidence of dark cutting within the study was 2.8%. Increased wind speeds (WSs) and rain during lairage at the abattoir was associated with an increased risk of dark cutting, whereas variation in ambient temperature and/or relative humidity did not influence dark cutting. Heavier carcasses with whiter fat, larger hump heights, more rib fat, higher marble scores and lower ossification had lower incidences of dark cutting. The factors abattoir, time in lairage, time to grading and grader within Abattoir had significant effects on the incidence of dark cutting. The results from this study suggest that reducing the time in lairage and increasing the time between slaughter and grading are the two major ways to reduce dark cutting in MSA carcasses.

15.
Clin Transl Oncol ; 23(4): 799-811, 2021 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32789772

RESUMO

BACKGROUND AND RATIONALE: Thromboembolic complications are a serious, preventable and common event in cancer patients that contributes to increasing morbidity and mortality. Despite increasing knowledge on cancer-associated thrombosis (CAT), there are still several aspects of diagnosis, clinical management, treatment and prognosis with uncertainties that are under-represented in randomized clinical trials. For this reason, the Spanish Society of Medical Oncology (SEOM) launched in June 2018 a registry of CAT. METHODS/DESIGN: TESEO is an ongoing prospective, non-interventional, multicentric study in consecutive cancer patients with newly diagnosed of thromboembolic event (TEE). Eligibility criteria include being > 18 years with a histologically confirmed diagnosis of cancer and a symptomatic or incidental TEE confirmed with an imaging technique in the previous month or any time after the cancer diagnosis and signing of informed consent. The study consists of two types of integrated but independent prospective registries. Regular CAT sub-registry includes information on patient's cancer´s characteristics, anticoagulant treatment provided and outcome data. Special CAT sub-registry includes variables related to special situations of CAT that comprise patients with severe kidney failure, thrombocytopenia, high risk of bleeding related to the cancer or with coexistence of bleeding and patients who receive new treatments such a targeted therapy, antiangiogenics agents and immunotherapy. The registry considers the status of the cancer and the time to assess how the prognosis is changed based on when the thrombus occurs. Some outcomes such as rethrombosis, major bleeding, tumor progression and survival will be valued in various time intervals including 1, 3, 6 and 12 months after the even in the first year; and then every 6 months until the patient's death. RESULTS: After 18 months and with 35 centers and researchers, the registry has 1128 patients. CONCLUSION: TESEO registry will provide clinical real-world evidence for prevention, treatment and complications of CAT in different scenarios that are under-represented in randomized clinical trials.


Assuntos
Neoplasias/complicações , Sistema de Registros/estatística & dados numéricos , Tromboembolia/epidemiologia , Inibidores da Angiogênese/uso terapêutico , Anticoagulantes/uso terapêutico , Progressão da Doença , Hemorragia/epidemiologia , Humanos , Imunoterapia , Oncologia , Terapia de Alvo Molecular , Neoplasias/terapia , Prognóstico , Recidiva , Insuficiência Renal/epidemiologia , Sociedades Médicas , Espanha/epidemiologia , Trombocitopenia/epidemiologia , Tromboembolia/tratamento farmacológico , Tromboembolia/etiologia , Tromboembolia/prevenção & controle , Resultado do Tratamento , Tromboembolia Venosa/tratamento farmacológico , Tromboembolia Venosa/epidemiologia , Tromboembolia Venosa/etiologia
16.
Phys Rev E ; 101(5-1): 052214, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32575306

RESUMO

We study theoretically the emergence of localized states of vegetation close to the onset of desertification. These states are formed through the locking of vegetation fronts, connecting a uniform vegetation state with a bare soil state, which occurs nearby the Maxwell point of the system. To study these structures we consider a universal model of vegetation dynamics in drylands, which has been obtained as the normal form for different vegetation models. Close to the Maxwell point localized gaps and spots of vegetation exist and undergo collapsed snaking. The presence of gaps strongly suggest that the ecosystem may undergo a recovering process. In contrast, the presence of spots may indicate that the ecosystem is close to desertification.

17.
Rev Neurol ; 70(5): 183-192, 2020 Mar 01.
Artigo em Espanhol | MEDLINE | ID: mdl-32100279

RESUMO

INTRODUCTION: Deep brain stimulation (DBS) in drug-resistant epilepsy has been applied to several brain targets. However, its exact mechanism of action is not known, and the diversity of targets makes it difficult to know the degree of evidence that supports its use. DEVELOPMENT: A review of the literature on DBS for drug-resistant epilepsy was conducted. The efficacy of DBS in drug-resistant epilepsy seems to be mediated by a desynchronisation of neuronal activity at the epileptogenic focus or a modulation of the «circuitopathies¼ that exist in epilepsy, depending on the target. In DBS multiple cortical and subcortical structures have been used, but class I evidence exists only for DBS of the anterior nucleus of the thalamus. CONCLUSIONS: DBS in epilepsy is still under investigation, with class I evidence for DBS of the anterior nucleus of the thalamus. The rest of the targets have yielded variable results that must be confirmed with randomised designs in larger series.


TITLE: Estimulación cerebral profunda en la epilepsia farmacorresistente.Introducción. La estimulación cerebral profunda (ECP) en la epilepsia farmacorresistente se ha aplicado en varias dianas cerebrales. Sin embargo, su mecanismo de acción no se conoce con exactitud, y la diversidad de dianas hace difícil conocer el grado de evidencia que apoya su utilización. Desarrollo. Se realiza una revisión bibliográfica sobre la ECP para la epilepsia farmacorresistente. La eficacia de la ECP en la epilepsia farmacorresistente parece mediada por una desincronización de la actividad neuronal en el foco epileptógeno o una modulación de las circuitopatías que existen en la epilepsia, dependiendo de la diana. En la ECP se han utilizado múltiples estructuras corticales y subcorticales, pero solamente la ECP del núcleo anterior del tálamo tiene una evidencia de clase I. Conclusiones. La ECP en la epilepsia es aún objeto de investigación, con evidencia de clase I en la ECP del núcleo anterior del tálamo. El resto de las dianas ha arrojado resultados variables que deben confirmarse con diseños aleatorizados en series de mayor tamaño.


Assuntos
Estimulação Encefálica Profunda/métodos , Epilepsia Resistente a Medicamentos/terapia , Animais , Anticonvulsivantes/uso terapêutico , Encéfalo/fisiopatologia , Região CA1 Hipocampal/fisiopatologia , Estimulação Encefálica Profunda/efeitos adversos , Ritmo Delta , Modelos Animais de Doenças , Epilepsia Resistente a Medicamentos/fisiopatologia , Medicina Baseada em Evidências , Potenciais Pós-Sinápticos Excitadores , Humanos , Especificidade de Órgãos , Ratos , Sinapses/fisiologia
18.
Rev Neurol ; 70(8): 293-299, 2020 Apr 16.
Artigo em Espanhol | MEDLINE | ID: mdl-32242336

RESUMO

INTRODUCTION: Deep brain stimulation is an effective therapy that is being used in an increasing number of indications. The mechanisms by which it exerts its therapeutic effect are still largely unknown, although there is increasing evidence of its influence at various levels. AIM: To review the existing literature on the mechanism of action of deep brain stimulation. DEVELOPMENT: Deep brain stimulation acts on brain tissue that is stimulated at various levels: molecular, cellular and neural networks. Spatial, temporal and electrical factors are involved in its effectiveness, but it mainly seems to perform its function by replacing anomalous firing patterns, which are present in certain neurological and psychiatric diseases. Other mechanisms, such as neuroprotection or neurogenesis, remain under study. CONCLUSIONS: Although many of the effects by which deep brain stimulation acts on the brain are still unknown, it seems to be a complex treatment, with large-scale effects, in which the correction of circuitopathies seems to prevail as the main mechanism.


TITLE: Bases de la estimulación cerebral profunda.Introducción. La estimulación cerebral profunda es una terapia eficaz que está siendo utilizada en un número creciente de indicaciones. Los mecanismos mediante los cuales ejerce efecto terapéutico aún se desconocen en su mayor parte, si bien cada vez se dispone de más datos sobre su influencia en diversos niveles. Objetivo. Revisar la bibliografía existente sobre el mecanismo de acción de la estimulación cerebral profunda. Desarrollo. La estimulación cerebral profunda actúa sobre el tejido cerebral estimulado en varios niveles, molecular, celular y de redes neuronales. En su efectividad intervienen factores espaciales, temporales y eléctricos, pero fundamentalmente parece ejercer su función mediante la sustitución de patrones de disparo anómalos, presentes en ciertas enfermedades neurológicas y psiquiátricas. Otros mecanismos, como la neuroprotección o la neurogénesis, permanecen en estudio. Conclusiones. Aunque aún se desconocen muchos efectos por los cuales la estimulación cerebral profunda actúa en el cerebro, parece un tratamiento complejo, con efectos a gran escala, en los que parece primar la corrección de circuitopatías como mecanismo principal.


Assuntos
Encefalopatias/terapia , Estimulação Encefálica Profunda , Transtornos Mentais/terapia , Encéfalo/fisiopatologia , Encefalopatias/fisiopatologia , Humanos , Transtornos Mentais/fisiopatologia
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