Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 48
Filtrar
1.
Rev Sci Instrum ; 90(11): 115114, 2019 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-31779406

RESUMO

We report on the design, construction, and performance of a compact magnetic shield that facilitates a controlled, low-noise environment for experiments with ultracold atomic gases. The shield was designed to passively attenuate external slowly varying magnetic fields while allowing for ample optical access. The geometry, number of layers, and choice of materials were optimized using extensive finite-element numerical simulations. The measured performance of the shield is in good agreement with the simulations. From measurements of the spin coherence of an ultracold atomic ensemble, we demonstrate a residual field noise of 2.6 µG and a suppression of external dc magnetic fields by more than five orders of magnitude.

2.
Epidemiol Infect ; 145(11): 2313-2323, 2017 08.
Artigo em Inglês | MEDLINE | ID: mdl-28566102

RESUMO

Early prediction of the final size of any epidemic and in particular for Zika disease outbreaks can be useful for health authorities in order to plan the response to the outbreak. The Richards model is often been used to estimate epidemiological parameters for arboviral diseases based on the reported cumulative cases in single- and multi-wave outbreaks. However, other non-linear models can also fit the data as well. Typically, one follows the so called post selection estimation procedure, i.e., selects the best fitting model out of the set of candidate models and ignores the model uncertainty in both estimation and inference since these procedures are based on a single model. In this paper we focus on the estimation of the final size and the turning point of the epidemic and conduct a real-time prediction for the final size of the outbreak using several non-linear models in which these parameters are estimated via model averaging. The proposed method is applied to Zika outbreak data in four cities from Colombia, during the outbreak ocurred in 2015-2016.


Assuntos
Surtos de Doenças , Modelos Teóricos , Infecção por Zika virus/epidemiologia , Zika virus/fisiologia , Cidades/epidemiologia , Colômbia/epidemiologia , Humanos , Incidência , Dinâmica não Linear , Infecção por Zika virus/virologia
3.
Phys Rev Lett ; 117(23): 239702, 2016 12 02.
Artigo em Inglês | MEDLINE | ID: mdl-27982607
4.
Phys Rev Lett ; 115(4): 046801, 2015 Jul 24.
Artigo em Inglês | MEDLINE | ID: mdl-26252703

RESUMO

The search in two-dimensional condensed matter systems of Rashba-type spin-polarized electronic states is aimed by the possibility to control and manipulate the spin orientation. In this Letter, for the first time, we report on the experimental evidence of a Rashba-type spin splitting in the n=1 image potential state. The image potential state Rashba splitting here measured at the graphene/Ir(111) interface, as confirmed by theoretical considerations, can be detectable to any metal surface with a significant spin-orbit coupling.

5.
J Neurosurg Sci ; 56(2): 137-43, 2012 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-22617176

RESUMO

AIM: This work reports the analysis of the relationship between inferior fronto-occipital fasciculus (IFO), neoplastic lesions and surgical resection, in patients operated for gliomas located in the frontal, temporal and insular lobes of the dominant hemisphere. Aim of the study is evaluating the predictive value of inferior fronto-occipital fasciculus DTI-fiber tracking (FT) for determining the extent of resection preoperatively. METHODS: We selected 38 cases affected by lesions located in the frontal, temporal and insular lobes of the dominant hemisphere, which were related to the trajectory of the IFO. For each patient preoperative and postoperative MR images and DTI-FT were loaded into the neuronavigation system and merged; volumetric scan analysis was used for establishing tumor location and topography, as well as the volume of the lesion and of the residual tumor. All preoperative fiber tracking datasets were evaluated and the position of the tract (IFO) compared to the tumor was recorded. Postoperative MR scans were then compared with DTI-FT, in order to evaluate the correspondence between the resection boundaries and the trajectory of the fiber tract. RESULTS: Amongst the cases in which the IFO was inside the lesion, we found only incomplete resections (5 subtotal and 6 partial resections), while considering the cases in which the IFO was located outside the tumor, it was possible to perform a relevant (total/subtotal) resection in 18 of them (78%). CONCLUSION: FT of the inferior frontal-occipital fasciculus predicts the possibility and the extent of the resection for a frontal, temporal and/or insular lesion of the dominant hemisphere.


Assuntos
Neoplasias Encefálicas/patologia , Neoplasias Encefálicas/cirurgia , Córtex Cerebral/cirurgia , Glioma/patologia , Glioma/cirurgia , Adulto , Córtex Cerebral/patologia , Feminino , Humanos , Processamento de Imagem Assistida por Computador , Imageamento por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Procedimentos Neurocirúrgicos , Valor Preditivo dos Testes
6.
Diabetologia ; 55(4): 1013-23, 2012 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-22252472

RESUMO

AIMS/HYPOTHESIS: Knowledge of number, size and content of insulin secretory granules is pivotal for understanding the physiology of pancreatic beta cells. Here we re-evaluated key structural features of rat beta cells, including insulin granule size, number and distribution as well as cell size. METHODS: Electron micrographs of rat beta cells fixed either chemically or by high-pressure freezing were compared using a high-content analysis approach. These data were used to develop three-dimensional in silico beta cell models, the slicing of which would reproduce the experimental datasets. RESULTS: As previously reported, chemically fixed insulin secretory granules appeared as hollow spheres with a mean diameter of ∼350 nm. Remarkably, most granules fixed by high-pressure freezing lacked the characteristic halo between the dense core and the limiting membrane and were smaller than their chemically fixed counterparts. Based on our analyses, we conclude that the mean diameter of rat insulin secretory granules is 243 nm, corresponding to a surface area of 0.19 µm(2). Rat beta cells have a mean volume of 763 µm(3) and contain 5,000-6,000 granules. CONCLUSIONS/INTERPRETATION: A major reason for the lower mean granule number/rat beta cell relative to previous accounts is a reduced estimation of the mean beta cell volume. These findings imply that each granule contains about twofold more insulin, while its exocytosis increases membrane capacitance about twofold less than assumed previously. Our integrated approach defines new standards for quantitative image analysis of beta cells and could be applied to other cellular systems.


Assuntos
Grânulos Citoplasmáticos/ultraestrutura , Células Secretoras de Insulina/ultraestrutura , Insulina/metabolismo , Vesículas Secretórias/ultraestrutura , Animais , Células Cultivadas , Grânulos Citoplasmáticos/metabolismo , Feminino , Células Secretoras de Insulina/metabolismo , Microscopia Eletrônica de Transmissão , Ratos , Ratos Wistar , Vesículas Secretórias/metabolismo
7.
Adv Tech Stand Neurosurg ; 35: 113-57, 2010.
Artigo em Inglês | MEDLINE | ID: mdl-20102113

RESUMO

Low-grade gliomas are slow growing intrinsic lesions that induces a progressive functional reshaping of the brain. Surgical removal of these lesions requires the combined efforts of a multidiscipinary team of neurosurgeon, neuroradiologist, neuropsychologist, neurophysiologist, and neurooncologists that all together contribute in the definition of the location, extension, and extent of functional involvement that a specific lesion has induced in a particular patient. Each tumor has induced particular and specific changes of the functional network, that varies among patients. This requires that each treatment plan should be tailored to the tumor and to the patient. When this is reached, surgery should be accomplished according to functional and anatomical boundaries, and has to aim to the maximal resection with the maximal patient functional preservation. This can be reached at the time of the initial surgery, depending on the functional organization of the brain, or may require additional surgeries, eventually intermingled with adjuvant treatments. The use of so called brain mapping techniques extend surgical indications, improve extent of resection with greater oncological impact, minimization of morbidity and increase in quality of life. To achieve the goal of a satisfactory tumor resection associated with the full preservation of the patients abilities, a series of neuropsychological, neurophysiological, neuroradiological and intraoperative investigations have to be performed. In this chapter, we will describe the rationale, the indications and the modality for performing a safe and rewarding surgical removal of low-grade gliomas by using these techniques, as well as the functional and oncological results.


Assuntos
Neoplasias Encefálicas/cirurgia , Glioma/cirurgia , Microcirurgia , Procedimentos Neurocirúrgicos , Mapeamento Encefálico , Neoplasias Encefálicas/patologia , Neoplasias Encefálicas/fisiopatologia , Glioma/patologia , Glioma/fisiopatologia , Humanos
8.
Exp Neurol ; 223(1): 229-37, 2010 May.
Artigo em Inglês | MEDLINE | ID: mdl-19682989

RESUMO

Amyotrophic Lateral Sclerosis (ALS) is a devastating incurable disease. Stem-cell-based therapies represent a new possible strategy for ALS clinical research. The objectives of this Phase 1 clinical study were to assess the feasibility and toxicity of mesenchymal stem cell transplantation and to test the impact of a cell therapy in ALS patients. The trial was approved and monitored by the National Institute of Health and by the Ethics Committees of all participating Institutions. Autologous MSCs were isolated from bone marrow, expanded in vitro and analyzed according to GMP conditions. Expanded MSCs were suspended in the autologous cerebrospinal fluid (CSF) and directly transplanted into the spinal cord at a high thoracic level with a surgical procedure. Ten ALS patients were enrolled and regularly monitored before and after transplantation by clinical, psychological, neuroradiological and neurophysiological assessments. There was no immediate or delayed transplant-related toxicity. Clinical, laboratory, and radiographic evaluations of the patients showed no serious transplant-related adverse events. Magnetic resonance images (MRI) showed no structural changes (including tumor formation) in either the brain or the spinal cord. However the lack of post mortem material prevents any definitive conclusion about the vitality of the MSCs after transplantation. In conclusion, this study confirms that MSC transplantation into the spinal cord of ALS patients is safe and that MSCs might have a clinical use for future ALS cell based clinical trials.


Assuntos
Esclerose Lateral Amiotrófica/cirurgia , Transplante de Células-Tronco Mesenquimais/métodos , Adulto , Idoso , Esclerose Lateral Amiotrófica/fisiopatologia , Antígenos CD/metabolismo , Células da Medula Óssea/fisiologia , Estudos de Coortes , Imagem de Difusão por Ressonância Magnética/métodos , Estimulação Elétrica/métodos , Potenciais Somatossensoriais Evocados/fisiologia , Feminino , Humanos , Imageamento por Ressonância Magnética/métodos , Masculino , Pessoa de Meia-Idade , Estudos Retrospectivos , Medula Espinal/patologia , Fatores de Tempo , Adulto Jovem
9.
J Neurosurg Sci ; 51(2): 45-51, 2007 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-17571034

RESUMO

AIM: Surgery for gliomas located inside or in proximity of motor cortex or tracts requires cortical and subcortical mapping to locate motor function; direct electrical stimulation of brain cortex or subcortical pathways allows identification and preservation of motor function. In this study we evaluated the effect which subcortical motor mapping had on postoperative morbidity and extent of resection in a series of patients with gliomas involving motor areas or pathways. METHODS: One hundred and forty-six patients were included in the study. Intraoperative findings of primary motor cortex or subcortical tracts were reported, together with incidence of new postoperative deficits at short (1 week) and long term (1 month) examination. The relationship between intraoperative identification of subcortical motor tracts and extent of resection was reported. RESULTS: The motor strip was found in 133 patients (91%) and subcortical motor tracts in 91 patients (62.3%). New immediate postoperative motor deficits were documented in 59.3% of patients in whom a subcortical motor tract was identified intra-operatively and in 10.9% of those in whom subcortical tracts were not observed; permanent deficits were observed in 6.5% and 3.5%, respectively. A total resection was achieved in 94.4% of patients with high-grade gliomas and in 46.1% of those with low-grade gliomas.


Assuntos
Mapeamento Encefálico/métodos , Neoplasias Encefálicas/diagnóstico , Vias Eferentes/fisiopatologia , Glioma/diagnóstico , Córtex Motor/fisiopatologia , Complicações Pós-Operatórias/prevenção & controle , Adulto , Idoso , Neoplasias Encefálicas/patologia , Neoplasias Encefálicas/cirurgia , Vias Eferentes/patologia , Vias Eferentes/cirurgia , Estimulação Elétrica/métodos , Eletrodiagnóstico/métodos , Eletroencefalografia/métodos , Glioma/patologia , Glioma/cirurgia , Humanos , Imageamento por Ressonância Magnética , Pessoa de Meia-Idade , Monitorização Intraoperatória/métodos , Córtex Motor/patologia , Córtex Motor/cirurgia , Transtornos dos Movimentos/prevenção & controle , Procedimentos Neurocirúrgicos/efeitos adversos , Procedimentos Neurocirúrgicos/métodos , Procedimentos Neurocirúrgicos/mortalidade , Complicações Pós-Operatórias/etiologia , Complicações Pós-Operatórias/mortalidade , Resultado do Tratamento
10.
Proc Natl Acad Sci U S A ; 103(40): 14802-7, 2006 Oct 03.
Artigo em Inglês | MEDLINE | ID: mdl-17003126

RESUMO

Cajal bodies are small nuclear organelles with a number of nuclear functions. Here we show that FLICE-associated huge protein (FLASH), originally described as a component of the apoptosis signaling pathway, is mainly localized in Cajal bodies and is essential for their structure. Reduction in FLASH expression by short hairpin RNA results in disruption of the normal architecture of the Cajal body and relocalization of its components. Because the function of FLASH in the apoptosis receptor signaling pathway has been strongly questioned, we have now identified a clear function for this protein.


Assuntos
Proteínas Reguladoras de Apoptose/metabolismo , Proteínas de Ligação ao Cálcio/metabolismo , Corpos Enovelados/metabolismo , Animais , Proteínas Reguladoras de Apoptose/ultraestrutura , Proteínas de Ligação ao Cálcio/ultraestrutura , Corpos Enovelados/patologia , Corpos Enovelados/ultraestrutura , Regulação para Baixo/genética , Células HeLa , Humanos , Camundongos , Sinais de Localização Nuclear/metabolismo , Proteínas Nucleares/metabolismo , Biossíntese de Proteínas/genética , Transporte Proteico , Proteínas Recombinantes de Fusão/metabolismo
11.
Cell Death Differ ; 9(8): 818-31, 2002 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-12107825

RESUMO

Neuronal death, which follows ischemic injury or is triggered by excitotoxins, can occur by both apoptosis and necrosis. Caspases, which are not directly required for necrotic cell death, are central mediators of the apoptotic program. Here we demonstrate that caspases cleave and inactivate the plasma membrane Ca(2+) pump (PMCA) in neurons and non-neuronal cells undergoing apoptosis. PMCA cleavage impairs intracellular Ca(2+) handling, which results in Ca(2+) overload. Expression of non-cleavable PMCA mutants prevents the disturbance in Ca(2+) handling, slows down the kinetics of apoptosis, and markedly delays secondary cell lysis (necrosis). These findings suggest that caspase-mediated cleavage and inactivation of PMCAs can lead to necrosis, an event that is reduced by caspase inhibitors in brain ischemia.


Assuntos
Apoptose/fisiologia , ATPases Transportadoras de Cálcio/metabolismo , Caspases/metabolismo , Membrana Celular/enzimologia , Hipóxia-Isquemia Encefálica/enzimologia , Necrose , Neurônios/enzimologia , Animais , Animais Recém-Nascidos , Apoptose/efeitos dos fármacos , Sítios de Ligação/efeitos dos fármacos , Sítios de Ligação/fisiologia , Células CHO , Cálcio/metabolismo , Sinalização do Cálcio/efeitos dos fármacos , Sinalização do Cálcio/fisiologia , ATPases Transportadoras de Cálcio/efeitos dos fármacos , Caspase 3 , Caspases/efeitos dos fármacos , Caspases/genética , Proteínas de Transporte de Cátions , Membrana Celular/efeitos dos fármacos , Células Clonais/citologia , Células Clonais/efeitos dos fármacos , Células Clonais/metabolismo , Corantes , Cricetinae , Hipóxia-Isquemia Encefálica/patologia , Hipóxia-Isquemia Encefálica/fisiopatologia , Imuno-Histoquímica , Líquido Intracelular/metabolismo , Camundongos , Mutação/efeitos dos fármacos , Mutação/genética , Neurônios/efeitos dos fármacos , Neurônios/patologia , Neurotoxinas/farmacologia , ATPases Transportadoras de Cálcio da Membrana Plasmática , Ratos
12.
Neuroreport ; 12(17): 3645-8, 2001 Dec 04.
Artigo em Inglês | MEDLINE | ID: mdl-11726766

RESUMO

The pathogenesis of some neurodegenerative disorders has been linked to excitotoxicity, excess generation of nitric oxide (NO) and apoptosis. Here, we used a model of NO-triggered neuronal apoptosis that was strictly dependent on autocrine NMDA receptor (NMDA-R) activation and intracellular Ca2+ increase. We investigated the efficiency and potentially beneficial effects of calpain inhibition. Three calpain inhibitors that prevented intracellular fodrin proteolysis also blocked apoptotic features such as decrease in mitochondrial membrane potential, chromatin breakdown, and subsequent death of cerebellar granule neurons exposed to NO donors (S-nitroso-L-glutathione, S-nitroso-N-acetyl-d,l-penicillamine, and diethylamino-diazenolate-2-oxide). Since inhibitors did not interfere with NMDA-R activation, we suggest that block of calpains blunts NO-triggered neuronal apoptosis by stopping the cascade downstream of primary autocrine excitotoxic events.


Assuntos
Apoptose/efeitos dos fármacos , Comunicação Autócrina/efeitos dos fármacos , Calpaína/antagonistas & inibidores , Inibidores Enzimáticos/farmacologia , Neurônios/efeitos dos fármacos , Óxido Nítrico/antagonistas & inibidores , Receptores de N-Metil-D-Aspartato/efeitos dos fármacos , Animais , Apoptose/fisiologia , Comunicação Autócrina/fisiologia , Cálcio/metabolismo , Sinalização do Cálcio/efeitos dos fármacos , Sinalização do Cálcio/fisiologia , Calpaína/metabolismo , Proteínas de Transporte/metabolismo , Células Cultivadas , Dano ao DNA/efeitos dos fármacos , Dano ao DNA/fisiologia , Relação Dose-Resposta a Droga , Antagonistas de Aminoácidos Excitatórios/farmacologia , Camundongos , Camundongos Endogâmicos , Proteínas dos Microfilamentos/metabolismo , Mitocôndrias/efeitos dos fármacos , Mitocôndrias/metabolismo , Mitocôndrias/patologia , Doenças Neurodegenerativas/tratamento farmacológico , Doenças Neurodegenerativas/metabolismo , Doenças Neurodegenerativas/fisiopatologia , Neurônios/metabolismo , Neurotoxinas/farmacologia , Óxido Nítrico/metabolismo , Doadores de Óxido Nítrico/farmacologia , Receptores de N-Metil-D-Aspartato/metabolismo
13.
Brain Pathol ; 10(2): 276-82, 2000 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-10764047

RESUMO

Recent work has shown that execution of the apoptotic program involves a relatively limited number of pathways. According to a general view, these would converge to activate the caspase family of proteases. However, there is increasing evidence that apoptotic-like features can be found also when cells are treated with inhibitors of caspases as the cell permeable tripeptide, Z-Val-Ala-Asp-fluoro-methyl-ketone (Z-VAD-fmk), or analogous compounds. This has posed the question as to whether apoptosis may occur in a caspase independent way, and whether caspase inhibitors may then be used to treat diseases characterised by an excess apoptosis. It is also becoming clear, that ATP depletion during the early phases of apoptosis can preclude caspase activation, and consequently switch execution of cell death towards necrosis. In vivo, a block or partial inhibition of the typical apoptotic demise may have profound implications, as persistence of damaged but "undead" cells within the nervous system, followed by delayed lysis may favour neuroinflammatory reactions. In this review, we discuss some recent findings, which suggest that cells may use diverging execution pathways, with different implications in neuropathology and therapy.


Assuntos
Caspases/metabolismo , Metabolismo Energético/fisiologia , Neurônios/fisiologia , Animais , Morte Celular/fisiologia , Ativação Enzimática/fisiologia
14.
Int J Soc Psychiatry ; 46(4): 290-305, 2000.
Artigo em Inglês | MEDLINE | ID: mdl-11201350

RESUMO

Enquiries centred on the perspective of users of psychiatric treatments and their families, has become an increasingly widespread method to improve the quality of treatments administered by health services. In this study, in particular, we examine the users' perception of the quality and variability of the effects of psychotherapies, the difficulties met, and the perceived help factors. The sample consists of 216 users of psychotherapy and 223 patients in psychiatric treatment with psychological support. They are outpatients, managed by the public health service. The questionnaires included closed ended, open-ended questions and scales that were previously tested on a sample of patients. The questionnaire for patients was anonymous and administered by researchers external to the medical staff. Irrespective of the diagnosis or of a concurrent pharmacological therapy, a high percentage of patients (75%), in both groups, feel improved. Improvement consist of the decrease of symptoms, a sense of feeling better, but also feeling grown up, more mature, having higher self-esteem and feeling more adequate in interpersonal relationships. This last type of result is significantly more frequent in the group of patients in psychotherapy. Besides these patients are faced with more difficulties and play more active a role while they are in treatment. The main difference between patients in psychotherapy and those in psychiatric management with psychological support is not indeed the identification of different perceived therapeutic factors, but rather the different evaluation of their relative importance. On the whole, the study seems to show that the effects of real psychotherapies include, beside an improvement of symptoms, the achievement of goals of personal growth and maturity, self-satisfaction and an increase in self-esteem, all in accordance with a conception of health as well-being and self-satisfaction rather than as absence of illness.


Assuntos
Comparação Transcultural , Transtornos Mentais/terapia , Satisfação do Paciente , Psicoterapia/métodos , Adaptação Psicológica , Adulto , Serviços Comunitários de Saúde Mental , Feminino , Humanos , Itália , Masculino , Transtornos Mentais/psicologia , Qualidade de Vida , Apoio Social , Resultado do Tratamento
15.
Dtsch Tierarztl Wochenschr ; 107(9): 351-4, 2000 Sep.
Artigo em Alemão | MEDLINE | ID: mdl-11471491

RESUMO

Chronically recidivating enzootic ulcerations in the tongues of numerous milking cows in the Po river plain area in Italy. The animals were permanently kept indoors in cubicle houses and fed by hay containing high amounts of ripe yellow bristle grass (Setaria glauca (L.) Beauv. [= S. pumila Poiret]). The panicled parts of the culms were found to be the cause of the massive injuries.


Assuntos
Doenças dos Bovinos/etiologia , Úlceras Orais/veterinária , Poaceae/efeitos adversos , Doenças da Língua/veterinária , Ração Animal , Animais , Bovinos , Doenças dos Bovinos/patologia , Feminino , Itália , Úlceras Orais/etiologia , Úlceras Orais/patologia , Língua/patologia , Doenças da Língua/etiologia , Doenças da Língua/patologia
17.
Chem Res Toxicol ; 12(10): 874-82, 1999 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-10525261

RESUMO

The toxicity of tributyltin chloride (TBT) involves Ca(2+) overload, cytoskeletal damage, and mitochondrial failure leading to cell death by apoptosis or necrosis. Here, we examined whether the intracellular ATP level modulates the mode of cell death after exposure to TBT. When Jurkat cells were energized by the mitochondrial substrate, pyruvate, low concentrations of TBT (1-2 microM) triggered an immediate depletion of intracellular ATP followed by necrotic death. When ATP levels were maintained by the addition of glucose, the mode of cell death was typically apoptotic. Glycolytic ATP production was required for apoptosis at two distinct steps. First, maintenance of adequate ATP levels accelerated the decrease of mitochondrial membrane potential, and the release of the intermembrane proteins adenylate kinase and cytochrome c from mitochondria. A possible role of the adenine nucleotide exchanger in this first ATP-dependent step is suggested by experiments performed with the specific inhibitor, bongkrekic acid. This substance delayed cytochrome c release in a manner similar to that caused by ATP depletion. Second, caspase activation following cytochrome c release was only observed in ATP-containing cells. Bcl-2 had only a minor effect on TBT-triggered caspase activation or cell death. We conclude that intracellular ATP concentrations control the mode of cell death in TBT-treated Jurkat cells at both the mitochondrial and caspase activation levels.


Assuntos
Trifosfato de Adenosina/biossíntese , Apoptose/efeitos dos fármacos , Glicólise/fisiologia , Compostos de Trialquitina/farmacologia , Ácido Bongcréquico/farmacologia , Caspases/metabolismo , Grupo dos Citocromos c/metabolismo , Metabolismo Energético/efeitos dos fármacos , Ativação Enzimática/efeitos dos fármacos , Humanos , Células Jurkat , Potenciais da Membrana/efeitos dos fármacos , Mitocôndrias/metabolismo , Dilatação Mitocondrial/efeitos dos fármacos , Fosforilação Oxidativa/efeitos dos fármacos , Proteínas/metabolismo
18.
Exp Cell Res ; 249(2): 396-403, 1999 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-10366439

RESUMO

Under pathological conditions, the mode of cell death, apoptosis or necrosis, is relevant for the subsequent fate of the tissue. Cell demise may be shaped by endogenous mediators such as nitric oxide (NO) which interfere with subroutines of the death program. Here we show that apoptosis of Jurkat cells elicited by either staurosporine (STS) or anti-CD95 antibodies in glucose-free medium is converted to necrosis by NO donors. In the presence of NO, release of mitochondrial cytochrome c was delayed and activation of execution caspases was prevented. Stimulated cells died nonetheless. The switch in the mode of cell death was due to NO-dependent failure of mitochondrial energy production. Restoration of intracellular ATP by glucose supplementation recovered the cells' ability to activate caspases and undergo apoptosis. In this system, the apoptosis/necrosis conversion promoted by NO was not mediated by cyclic guanosine monophosphate-dependent mechanisms, poly-(ADP-ribose)-polymerase (PARP) activation, or inhibition of caspases due to S-nitrosylation and glutathione depletion. In contrast, depleting intracellular ATP with rotenone, an inhibitor of mitochondrial complex I mimicked the effect of NO. The findings presented here suggest that NO can decide the shape of cell death by lowering intracellular ATP below the level required to allow the coordinated execution of apoptosis.


Assuntos
Trifosfato de Adenosina/antagonistas & inibidores , Apoptose/fisiologia , Mitocôndrias/metabolismo , Mitocôndrias/patologia , Óxido Nítrico/fisiologia , Trifosfato de Adenosina/metabolismo , Caspases/metabolismo , Grupo dos Citocromos c/metabolismo , Transporte de Elétrons/fisiologia , Humanos , Células Jurkat , Mitocôndrias/fisiologia , Necrose
19.
Biochem Biophys Res Commun ; 258(1): 215-21, 1999 Apr 29.
Artigo em Inglês | MEDLINE | ID: mdl-10222263

RESUMO

The endogenous mediator nitric oxide (NO) blocked apoptosis of Jurkat cells elicited by staurosporine, anti-CD95 or chemotherapeutics, and switched death to necrosis. The switch in the mode of cell death was dependent on the ATP loss elicited by NO. This affected two distinct steps of the apoptotic cascade. First, the release of cytochrome c from mitochondria was delayed by NO. Second, processing of procaspases-3/7 to the active proteases was prevented even after cytochrome c had been released. Thus, NO interferes with execution steps of apoptosis both upstream and downstream of cytochrome c release.


Assuntos
Trifosfato de Adenosina/metabolismo , Apoptose/fisiologia , Grupo dos Citocromos c/metabolismo , Mitocôndrias/enzimologia , Óxido Nítrico/fisiologia , Caspases/metabolismo , Núcleo Celular/metabolismo , Ativação Enzimática , Humanos , Células Jurkat , Mitocôndrias/efeitos dos fármacos , Doadores de Óxido Nítrico/farmacologia , Fosfatidilserinas/metabolismo
20.
Mol Pharmacol ; 54(5): 789-801, 1998 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-9804614

RESUMO

The pathogenesis of several neurodegenerative diseases may involve indirect excitotoxic mechanisms, where glutamate receptor overstimulation is a secondary consequence of initial functional defects of neurons (e.g., impairment of mitochondrial energy generation). The neurotoxin 1-methyl-4-phenylpyridinium (MPP+) and other mitochondrial inhibitors (e.g., rotenone or 3-nitropropionic acid) elicited apoptosis in cerebellar granule cell cultures via stimulation of autocrine excitotoxicity. Cell death, increase in intracellular Ca2+ concentration, release of cytochrome c, and all biochemical and morphological signs of apoptosis were prevented by blockade of the N-methyl-D-aspartate receptor with noncompetitive, glycine-site or glutamate-site inhibitors. In addition, MPP+-induced apoptosis was reduced by high Mg2+ concentrations in the medium or by inhibiting exocytosis with clostridial neurotoxins. Two classes of cysteine proteases were involved in the execution of cell death: caspases and calpains. Inhibitors of either class of proteases prevented cell death, cleavage of intracellular proteins (i.e., fodrin), and the appearance of typical features of apoptosis such as phosphatidylserine translocation or DNA fragmentation. However, protease inhibitors did not interfere with the initial intracellular Ca2+ concentration increase. We suggest that MPP+ as well as other mitochondrial inhibitors trigger indirect excitotoxic processes, which lead to Ca2+ overload, protease activation, and subsequent neuronal apoptosis.


Assuntos
1-Metil-4-fenilpiridínio/toxicidade , Apoptose/efeitos dos fármacos , Calpaína/metabolismo , Caspases/metabolismo , Neurônios/efeitos dos fármacos , Trifosfato de Adenosina/metabolismo , Animais , Apoptose/fisiologia , Cálcio/metabolismo , Calpaína/efeitos dos fármacos , Inibidores de Caspase , Caspases/efeitos dos fármacos , Células Cultivadas , Cromatina/efeitos dos fármacos , Cromatina/metabolismo , Ativação Enzimática , Exocitose/efeitos dos fármacos , Membranas Intracelulares/efeitos dos fármacos , Membranas Intracelulares/fisiologia , Potenciais da Membrana/efeitos dos fármacos , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL , Mitocôndrias/efeitos dos fármacos , Mitocôndrias/fisiologia , Neurônios/citologia , Neurônios/metabolismo , Óxido Nítrico/biossíntese , Inibidores de Proteases/farmacologia , Receptores de N-Metil-D-Aspartato/antagonistas & inibidores , Receptores de N-Metil-D-Aspartato/fisiologia , Rotenona/farmacologia , Desacopladores/farmacologia
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA