Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 184
Filtrar
1.
Phys Rev Lett ; 128(13): 132502, 2022 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-35426711

RESUMO

Differential cross sections for Compton scattering from the proton have been measured at scattering angles of 55°, 90°, and 125° in the laboratory frame using quasimonoenergetic linearly (circularly) polarized photon beams with a weighted mean energy value of 83.4 MeV (81.3 MeV). These measurements were performed at the High Intensity Gamma-Ray Source facility at the Triangle Universities Nuclear Laboratory. The results are compared to previous measurements and are interpreted in the chiral effective field theory framework to extract the electromagnetic dipole polarizabilities of the proton, which gives α_{E1}^{p}=13.8±1.2_{stat}±0.1_{BSR}±0.3_{theo},ß_{M1}^{p}=0.2∓1.2_{stat}±0.1_{BSR}∓0.3_{theo} in units of 10^{-4} fm^{3}.

3.
J Med Case Rep ; 15(1): 98, 2021 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-33648567

RESUMO

BACKGROUND: Hemophagocytic lymphohistiocytosis (HLH) is characterized by hyperinflammation and life-threatening cytopenias. Survival is poor, and management is pivotal on rapid identification of the disease. HLH is associated with hematologic malignancies, however correlation with myelodysplastic syndromes (MDS) is exceedingly unusual. Although minimizing overwhelming hyperinflammation by treating hemophagocytosis are central for HLH outcome, there is urgent necessity to identify potential initiating mechanisms that could assist in therapy design. CASE DESCRIPTION: Here, we describe an elderly African American patient who developed rapid onset of cytopenias and coagulopathy associated with hepatic and bone marrow hemophagocytosis. We analyze four additional similar cases to isolate clinical, laboratory and cytogenetic findings expected in patients exhibiting concurrent HLH and MDS. HLH linked with MDS retains common HLH features associated with systemic hyperinflammation such as fever, hypotension, hepatosplenomegaly, hyperferritinemia, coagulopathy and rapidly evolving cytopenias. Typical MDS chromosomic abnormality such as trisomy 8 was frequently observed in our studied cases. CONCLUSION: Our case describes difficulties while managing HLH in MDS patients. Diagnosis should be based on identifying HLH appropriate criteria and if possible karyotypic abnormalities normally observed in MDS.


Assuntos
Linfo-Histiocitose Hemofagocítica/diagnóstico , Linfo-Histiocitose Hemofagocítica/genética , Síndromes Mielodisplásicas/diagnóstico , Síndromes Mielodisplásicas/genética , Idoso de 80 Anos ou mais , Medula Óssea/patologia , Cromossomos Humanos Par 8 , Evolução Fatal , Feminino , Humanos , Cariótipo , Trissomia
6.
Oxid Med Cell Longev ; 2017: 8510761, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-29163756

RESUMO

The increase in the elderly population has generated concern to meet health demands. The research efforts to elucidate the mechanisms of damage associated with aging have also been significantly increased, especially in order to avoid the reduction of the cognitive abilities in geriatric patients, resulting from the damage generated mainly at the level of the hippocampus during old age. At present, many studies describe resveratrol as an antiaging component. There are reports that it can activate the Sirt1 gene related to antiaging, emulating the effects obtained by caloric restriction in rodents. The aim of the study was to evaluate the effect of chronic administration of resveratrol (10 mg/kg) on cognitive performance in behavioral tests after 8 months of treatment and on the preservation of cerebral integrity in the cytoarchitecture of regions CA1 and CA2. Results showed that the cytoarchitecture of the CA1 and CA2 regions in the hippocampus retained their integrity over time in rats treated with resveratrol, and the behavioral test performed revealed that chronic resveratrol administration for 8 months showed improvements in cognitive performance. The results indicate that resveratrol may exhibit therapeutic potential for age-related conditions.


Assuntos
Cognição/efeitos dos fármacos , Estilbenos/uso terapêutico , Envelhecimento , Animais , Vias de Administração de Medicamentos , Masculino , Ratos , Ratos Wistar , Resveratrol , Estilbenos/farmacologia
8.
Rev. esp. anestesiol. reanim ; 64(1): 27-31, ene. 2017. tab, graf
Artigo em Espanhol | IBECS | ID: ibc-158901

RESUMO

Objetivo. El objetivo de este estudio fue describir el perfil de utilización y las limitaciones del uso de la anestesia regional en países de América del Sur. Métodos. Tras la aprobación del comité de ética institucional, se envió un enlace a una encuesta en línea por e-mail a anestesiólogos de Argentina, Bolivia, Chile, Colombia, Panamá, Paraguay, Perú y Uruguay. La encuesta se procesó de forma anónima. Resultados. Se recibieron un total de 1.260 cuestionarios completos. El 97,6% de los anestesiólogos encuestados refiere utilizar anestesia regional en su práctica clínica habitual, el 66,9% realiza bloqueos de nervio periférico (BNP) con regularidad, el 21,6% usa técnicas de BNP continuo y un 4,6% usa catéteres estimulantes. La principal fuente de formación fueron los programas de residencia. En cuanto a los BNP más usados, los más comunes son el interescalénico (52,3%), el axilar (45,1%), el femoral (43,2%) y el de tobillo (43%). En cuanto a la técnica de neurolocalización, el 16% utiliza parestesia, el 44,2% estimulador de nervio periférico y un 18,1% ultrasonografía. Conclusiones. La anestesia regional y los BNP son de uso común entre los anestesiólogos de América del Sur. Cada país tiene su propio perfil de utilización y sus propias limitaciones para su uso. Dicho perfil debe ser tomado en cuenta a la hora de planificar las distintas formas de entrenamiento, en especial los programas de residencia (AU)


Objective. A survey was conducted in order to obtain a profile of the practice of regional anesthesia in South America, and determine the limitations of its use. Methods. After institutional ethics committee approval, a link to an online questionnaire was sent by e-mail to anaesthesiologists in Argentina, Bolivia, Chile, Colombia, Panamá, Paraguay, Perú, and Uruguay. The questionnaire was processed anonymously. Results. A total of 1,260 completed questionnaires were received. The results showed that 97.6% of the anaesthesiologists that responded used regional anaesthesia in clinical practice, 66.9% performed peripheral nerve block (PNB) regularly, 21.6% used continuous PNB techniques, and 4.6% used stimulating catheters. The primary source of training was residency programs. As regards PNB, the most common performed were interscalene (52.3%), axillary (45.1%), femoral (43.2%), and ankle block (43%). As regards the localisation technique employed, 16% used paraesthesia, 44.2% used a peripheral nerve stimulator, and 18.1% ultrasound guidance. Conclusions. Regional anaesthesia and PNB are commonly used among South American anaesthesiologists. Considering that each country has its own profile for use, this profile should guide training in clinical practice, especially in residency programs (AU)


Assuntos
Humanos , Masculino , Feminino , Anestesia por Condução/instrumentação , Anestesia por Condução/métodos , Anestesia por Condução , Nervos Periféricos , Anestesia por Condução/estatística & dados numéricos , Anestesia por Condução/tendências , América do Sul/epidemiologia , Inquéritos e Questionários , Sistema Nervoso Periférico , Anestesiologia , Anestesiologia/estatística & dados numéricos
9.
Rev Esp Anestesiol Reanim ; 64(1): 27-31, 2017 Jan.
Artigo em Inglês, Espanhol | MEDLINE | ID: mdl-27377713

RESUMO

OBJECTIVE: A survey was conducted in order to obtain a profile of the practice of regional anesthesia in South America, and determine the limitations of its use. METHODS: After institutional ethics committee approval, a link to an online questionnaire was sent by e-mail to anaesthesiologists in Argentina, Bolivia, Chile, Colombia, Panamá, Paraguay, Perú, and Uruguay. The questionnaire was processed anonymously. RESULTS: A total of 1,260 completed questionnaires were received. The results showed that 97.6% of the anaesthesiologists that responded used regional anaesthesia in clinical practice, 66.9% performed peripheral nerve block (PNB) regularly, 21.6% used continuous PNB techniques, and 4.6% used stimulating catheters. The primary source of training was residency programs. As regards PNB, the most common performed were interscalene (52.3%), axillary (45.1%), femoral (43.2%), and ankle block (43%). As regards the localisation technique employed, 16% used paraesthesia, 44.2% used a peripheral nerve stimulator, and 18.1% ultrasound guidance. CONCLUSIONS: Regional anaesthesia and PNB are commonly used among South American anaesthesiologists. Considering that each country has its own profile for use, this profile should guide training in clinical practice, especially in residency programs.


Assuntos
Anestesia por Condução/estatística & dados numéricos , Adulto , Anestesiologia/educação , Anestesiologia/tendências , Educação de Pós-Graduação em Medicina , Eletrodiagnóstico/estatística & dados numéricos , Pesquisas sobre Atenção à Saúde , Humanos , Pessoa de Meia-Idade , Bloqueio Nervoso/estatística & dados numéricos , Padrões de Prática Médica/estatística & dados numéricos , América do Sul , Inquéritos e Questionários , Ultrassonografia de Intervenção/estatística & dados numéricos
10.
Molecules ; 21(7)2016 Jul 22.
Artigo em Inglês | MEDLINE | ID: mdl-27455223

RESUMO

Chlorophyll is a pyrrolic pigment with important optical properties, which is the reason it has been studied for many years. Recently, interest has been rising with respect to this molecule because of its outstanding physicochemical properties, particularly applicable to the design and development of luminescent materials, hybrid sensor systems, and photodynamic therapy devices for the treatment of cancer cells and bacteria. More recently, our research group has been finding evidence for the possibility of preserving these important properties of substrates containing chlorophyll covalently incorporated within solid pore matrices, such as SiO2, TiO2 or ZrO2 synthesized through the sol-gel process. In this work, we study the optical properties of silica xerogels organo-modified on their surface with allyl and phenyl groups and containing different concentrations of chlorophyll bonded to the pore walls, in order to optimize the fluorescence that these macrocyclic species displays in solution. The intention of this investigation was to determine the maximum chlorophyll a concentration at which this molecule can be trapped inside the pores of a given xerogel and to ascertain if this pigment remains trapped as a monomer, a dimer, or aggregate. Allyl and phenyl groups were deposited on the surface of xerogels in view of their important effects on the stability of the molecule, as well as over the fluorescence emission of chlorophyll; however, these organic groups allow the trapping of either chlorophyll a monomers or dimers. The determination of the above parameters allows finding the most adequate systems for subsequent in vitro or in vivo studies. The characterization of the obtained xerogels was performed through spectroscopic absorption, emission and excitation spectra. These hybrid systems can be employed as mimics of natural systems; the entrapment of chlorophyll inside pore matrices indicates that it is possible to exploit some of the most physicochemical properties of trapped chlorophyll for diverse technological applications. The data herein collected suggest the possibility of applying the developed methodology to other active, captive molecules in order to synthesize new hybrid materials with optimized properties, suitable to be applied in diverse technological fields.


Assuntos
Clorofila/química , Sílica Gel/química , Clorofila/administração & dosagem , Clorofila A , Portadores de Fármacos/química , Fluorescência , Hidrólise , Modelos Moleculares , Estrutura Molecular , Espectroscopia Fotoeletrônica , Solventes , Espectrometria de Fluorescência , Espectrofotometria Ultravioleta
11.
J Fluoresc ; 26(5): 1601-16, 2016 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-27324951

RESUMO

Most of the studies performed with porphyrins involve these species functionalized with peripheral substituents lying on the same macrocyclic molecular plane. The main objective of this work deals with the successful preservation and optimization of the fluorescence of a uncommonly used porphyrin species, i.e. tetrakis-(ortho-amino-phenyl)-porphyrin; a molecule with substituents localized not only at one but at both sides of its molecular plane. In cases like this, it must be stressed that fluorescence can only be partially preserved; nevertheless, intense fluorescence can still be reached by following a twofold functionalization strategy involving: (i) the bonding of substituted macrocycles to the pore walls of (ii) organo-modified silica monoliths synthesized by the sol-gel method. The analysis of both absorption and emission UV spectra evidenced a radiation energy transfer taking place between the porphyrin and the host silica matrix. Our results showed that the adequate displaying of the optical properties of macrocyclic species trapped in SiO2 xerogels depend on the polarity existing inside the pores, a property which can be tuned up through the adequate selection of organic groups used to modify the surface of the pore cavities. Additionally, the pore widths attained in the final xerogels can vary depending on the identity of the organic groups attached to the network. All these facts finally demonstrated that, even if using inefficient surface functionalization species, such as ortho-substituted tetraphenylporphyrins, it is still possible to modulate the pore shape, pore size, and physicochemical environment created around the trapped macrocycles. The most important aspect related to this research deals with the fact that the developed methodology offers a real possibility of controlling both the textural and morphological characteristics of a new kind of hybrid porous materials and to optimize the physicochemical properties of diverse active molecules trapped inside the pores of these materials.

12.
Gynecol Oncol ; 140(3): 420-4, 2016 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-26790773

RESUMO

OBJECTIVES: To evaluate the changes in prognostic impression and patient management following PET/CT in patients with vulvar and vaginal carcinoma; and to compare PET/CT findings with those of conventional imaging modalities. METHODS: We summarized prospectively and retrospectively collected data for 50 consecutive patients from our institution that enrolled in the National Oncologic PET Registry and underwent FDG-PET/CT for a suspected or known primary or recurrent vulvar/vaginal cancer. RESULTS: 54/83 (65%) studies included had a diagnosis of vulvar cancer, and the remaining 29/83 (35%), a diagnosis of vaginal cancer. Following FDG-PET/CT, the physician's prognostic impression changed in 51% of cases. A change in patient management, defined as a change to/from a non-interventional strategy (observation or additional imaging), to/from an interventional strategy (biopsy or treatment), was documented in 36% of studies. The electronic records demonstrated that 95% of the management strategies recorded in the physician questionnaires were implemented as planned. MRI and/or CT were performed within one month of the FDG-PET/CT in 20/83 (24%) and 28/83 (34%) cases, respectively. FDG-PET/CT detected nodes suspicious for metastases on 29/83 (35%) studies performed. MRI and CT detected positive nodes on 6 and 11 studies respectively. Distant metastases were identified in 10 cases imaged with FDG-PET and 5 cases that had additional conventional CT imaging. All suspicious lesions seen on CT were positively identified on PET/CT. In 4 cases, an abnormality identified on PET/CT, was not seen on diagnostic CT. CONCLUSIONS: FDG-PET/CT may play an important role in the management of vulvar and vaginal carcinoma.


Assuntos
Carcinoma/diagnóstico , Tomografia por Emissão de Pósitrons , Tomografia Computadorizada por Raios X , Neoplasias Vaginais/diagnóstico , Neoplasias Vulvares/diagnóstico , Carcinoma/secundário , Carcinoma/terapia , Gerenciamento Clínico , Feminino , Fluordesoxiglucose F18 , Humanos , Metástase Linfática , Imagem Multimodal , Prognóstico , Estudos Prospectivos , Compostos Radiofarmacêuticos , Estudos Retrospectivos , Neoplasias Vaginais/terapia , Neoplasias Vulvares/terapia
13.
Artigo em Inglês | MEDLINE | ID: mdl-26565334

RESUMO

We undertake the analysis of soap-film dynamics with the classical approach of asymptotic expansions. We focus our analysis in vertical soap film tunnels operating in subcritical regimes with elastic Mach numbers M(e)=O((10(-1))). Considering the associated set of nondimensional numbers that characterize this flow, we show that the flow behaves as a two-dimensional (2D) divergence free flow with variable mass density. When the soap film dynamics agrees with that of a 2D and almost constant mass density flow, the regions where the second invariant of the velocity gradient is non-null correspond to regions where the rate of change of film thickness is non-negligible.

14.
Eur Radiol ; 25(11): 3348-53, 2015 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-25916387

RESUMO

OBJECTIVE: Our aim was to evaluate the associations between quantitative (18)F-fluorodeoxyglucose positron-emission tomography (FDG-PET) uptake metrics, optimal debulking (OD) and progression-free survival (PFS) in patients with recurrent ovarian cancer undergoing secondary cytoreductive surgery. METHODS: Fifty-five patients with recurrent ovarian cancer underwent FDG-PET/CT within 90 days prior to surgery. Standardized uptake values (SUVmax), metabolically active tumour volumes (MTV), and total lesion glycolysis (TLG) were measured on PET. Exact logistic regression, Kaplan-Meier curves and the log-rank test were used to assess associations between imaging metrics, OD and PFS. RESULTS: MTV (p = 0.0025) and TLG (p = 0.0043) were associated with OD; however, there was no significant association between SUVmax and debulking status (p = 0.83). Patients with an MTV above 7.52 mL and/or a TLG above 35.94 g had significantly shorter PFS (p = 0.0191 for MTV and p = 0.0069 for TLG). SUVmax was not significantly related to PFS (p = 0.10). PFS estimates at 3.5 years after surgery were 0.42 for patients with an MTV ≤ 7.52 mL and 0.19 for patients with an MTV > 7.52 mL; 0.46 for patients with a TLG ≤ 35.94 g and 0.15 for patients with a TLG > 35.94 g. CONCLUSION: FDG-PET metrics that reflect metabolic tumour burden are associated with optimal secondary cytoreductive surgery and progression-free survival in patients with recurrent ovarian cancer. KEY POINTS: • Both TLG and MTV were associated with optimal tumour debulking. • There was no significant association between SUVmax and tumour debulking status. • Patients with higher MTV and/or TLG had significantly shorter PFS. • SUVmax was not significantly related to PFS.


Assuntos
Fluordesoxiglucose F18 , Neoplasias Epiteliais e Glandulares/cirurgia , Neoplasias Ovarianas/cirurgia , Compostos Radiofarmacêuticos , Idoso , Idoso de 80 Anos ou mais , Carcinoma Epitelial do Ovário , Tomografia Computadorizada de Feixe Cônico , Procedimentos Cirúrgicos de Citorredução/métodos , Intervalo Livre de Doença , Feminino , Glicólise/fisiologia , Humanos , Pessoa de Meia-Idade , Imagem Multimodal/métodos , Recidiva Local de Neoplasia , Neoplasias Epiteliais e Glandulares/patologia , Neoplasias Ovarianas/patologia , Tomografia por Emissão de Pósitrons/métodos , Prognóstico , Estudos Retrospectivos , Tomografia Computadorizada por Raios X/métodos , Carga Tumoral
15.
J Urol ; 193(3): 851-6, 2015 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-25234299

RESUMO

PURPOSE: Delivering the recommended care is an important quality measure that has been insufficiently studied in urology. Obstructive pyelonephritis is a suitable case study for this focus because many patients do not receive such care, although guidelines advocate decompression. We determined the influence of hospital factors, particularly familiarity with urolithiasis, on the likelihood of decompression in such patients. MATERIALS AND METHODS: We used the NIS from 2002 to 2011 to retrospectively identify patients admitted to community hospitals with severe infection and ureteral calculi. Hospital familiarity with nephrolithiasis was estimated by calculating hospital stone volume (divided into quartiles) and hospital treatment intensity (the decompression rate in patients with ureteral calculi and no infection). After calculating national estimates we performed logistic regression to determine the association between the receipt of decompression and hospital stone volume, controlling for treatment intensity and other covariates thought to be associated with receiving recommended care. RESULTS: Of an estimated 107,848 patients with obstructive pyelonephritis 27.4% failed to undergo decompression. Discrepancies were greatest between hospitals with the highest and lowest stone volumes (76% vs 25%, OR 2.77, 95% CI 1.94-3.96, p <0.01) as well as high and low treatment intensity (78% vs 37%, p <0.01). CONCLUSIONS: High hospital stone volume and treatment intensity were associated with an increased likelihood of receiving decompression. Such findings might be useful to identify hospitals and regions where access to quality urological care should be augmented.


Assuntos
Serviços Médicos de Emergência/estatística & dados numéricos , Tratamento de Emergência/estatística & dados numéricos , Hospitais Comunitários/estatística & dados numéricos , Pielonefrite/terapia , Idoso , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Pielonefrite/etiologia , Cálculos Ureterais/complicações
17.
Cold Spring Harb Perspect Biol ; 6(9): a017004, 2014 Sep 02.
Artigo em Inglês | MEDLINE | ID: mdl-25183831

RESUMO

The roles of clathrin, its regulators, and the ESCRT (endosomal sorting complex required for transport) proteins are well defined in endocytosis. These proteins can also participate in intracellular pathways that are independent of endocytosis and even independent of the membrane trafficking function of these proteins. These nonendocytic functions involve unconventional biochemical interactions for some endocytic regulators, but can also exploit known interactions for nonendocytic functions. The molecular basis for the involvement of endocytic regulators in unconventional functions that influence the cytoskeleton, cell cycle, signaling, and gene regulation are described here. Through these additional functions, endocytic regulators participate in pathways that affect infection, glucose metabolism, development, and cellular transformation, expanding their significance in human health and disease.


Assuntos
Núcleo Celular/metabolismo , Clatrina/metabolismo , Citoesqueleto/metabolismo , Endocitose/fisiologia , Complexos Endossomais de Distribuição Requeridos para Transporte/metabolismo , Animais , Apoptose , Ciclo Celular , Divisão Celular , Membrana Celular/metabolismo , Dimerização , Regulação da Expressão Gênica , Glucose/metabolismo , Humanos , Doença de Huntington/metabolismo , Transdução de Sinais
18.
J Endourol ; 26(9): 1242-6, 2012 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-22545804

RESUMO

BACKGROUND AND PURPOSE: Noncontrast abdominal/pelvic CT is the current imaging standard for patients who present with acute urinary colic. Conventional CT, however, exposes the patient to significant amounts of ionizing radiation, which is cumulative when additional CTs are used to monitor stone migration, outcomes, etc. We sought to maintain diagnostic adequacy while decreasing our patients' radiation exposure from CT by using a reduced tube current, an abbreviated scanning area, and the use of coronal reformatted images. PATIENTS AND METHODS: Between March 3, 2011 and October 31, 2011, 101 consecutive adult patients with suspected urinary colic were evaluated with a "low" dose CT. If the suspected calculus(i) was not seen, the patient underwent immediate conventional CT imaging customized to their body habitus. Radiation exposure for each patient was calculated using an established formula of dose length product and scan length. The effective total radiation dose was measured in millisieverts (mSv). RESULTS: Overall, 84 patients had an upper tract calculus(i) consistent with the clinical suspicion. Of these, 76 (90%) were adequately imaged with low dose and 8 (10%) with conventional noncontrast CTs. The mean effective radiation dose in the 76 low dose stone-positive CTs was 2.14 mSV (median 2.10 mSv). This was almost seven-fold lower than the mean conventional stone-positive CT dose of 14.5 mSv (median 13.1 mSv). CONCLUSIONS: Low dose noncontrast CT provided adequate imaging to guide optimal urologic management in the majority of our patients. This modality offered a significantly lower ionizing radiation dose and should be considered in patients who present with acute urinary colic.


Assuntos
Cólica/diagnóstico por imagem , Tomografia Computadorizada por Raios X/métodos , Cálculos Urinários/diagnóstico por imagem , Doença Aguda , Adulto , Idoso , Idoso de 80 Anos ou mais , Relação Dose-Resposta à Radiação , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Variações Dependentes do Observador , Reprodutibilidade dos Testes , Cálculos Urinários/patologia , Adulto Jovem
19.
Appl Radiat Isot ; 70(7): 1403-6, 2012 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-22221466

RESUMO

The present paper reports the experimental results of dysprosium doped calcium sulphate (CaSO4:Dy) films deposited by spray pyrolysis method. CaSO4:Dy films were deposited on three different surfaces: glass, aluminum and quartz substrates at temperatures in the range from 450 to 600 °C. Structural and morphological characteristics of CaSO4:Dy films were observed. Thermoluminescent characteristics of films were determined by irradiating ultraviolet energy region. Thermoluminescent glow curve of CaSO4:Dy films with glass and aluminum substrates showed a peak under environmental irradiation. Both TL response glow shape and intensity of CaSO4:Dy films UV irradiated as a function of substrates were studied.

20.
Traffic ; 13(2): 305-16, 2012 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-22050483

RESUMO

The assembly of clathrin-coated vesicles is important for numerous cellular processes, including nutrient uptake and membrane organization. Important contributors to clathrin assembly are four tetrameric assembly proteins, also called adaptor proteins (APs), each of which contains a ß subunit. We identified a single ß subunit, named ß1/2, that contributes to both the AP1 and AP2 complexes of Dictyostelium. Disruption of the gene encoding ß1/2 resulted in severe defects in growth, cytokinesis and development. Additionally, cells lacking ß1/2 displayed profound osmoregulatory defects including the absence of contractile vacuoles and mislocalization of contractile vacuole markers. The phenotypes of ß1/2 null cells were most similar to previously described phenotypes of clathrin and AP1 mutants, supporting a particularly important contribution of AP1 to clathrin pathways in Dictyostelium cells. The absence of ß1/2 in cells led to significant reductions in the protein amounts of the medium-sized subunits of the AP1 and AP2 complexes, establishing a role for the ß subunit in the stability of the medium subunits. Dictyostelium ß1/2 could resemble a common ancestor of the more specialized ß1 and ß2 subunits of the vertebrate AP complexes. Our results support the essential contribution of a single ß subunit to the stability and function of AP1 and AP2 in a simple eukaryote.


Assuntos
Complexo 1 de Proteínas Adaptadoras/metabolismo , Complexo 2 de Proteínas Adaptadoras/metabolismo , Subunidades beta do Complexo de Proteínas Adaptadoras/metabolismo , Clatrina/metabolismo , Dictyostelium/fisiologia , Complexo 1 de Proteínas Adaptadoras/genética , Complexo 2 de Proteínas Adaptadoras/genética , Subunidades alfa do Complexo de Proteínas Adaptadoras/genética , Subunidades alfa do Complexo de Proteínas Adaptadoras/metabolismo , Subunidades beta do Complexo de Proteínas Adaptadoras/genética , Subunidades mu do Complexo de Proteínas Adaptadoras/genética , Subunidades mu do Complexo de Proteínas Adaptadoras/metabolismo , Subunidades sigma do Complexo de Proteínas Adaptadoras/genética , Sequência de Aminoácidos/fisiologia , Agregação Celular/fisiologia , Membrana Celular/metabolismo , Proliferação de Células , Quimiotaxia/fisiologia , Clatrina/genética , Cadeias Pesadas de Clatrina/genética , Cadeias Pesadas de Clatrina/metabolismo , Clonagem Molecular , Citocinese/fisiologia , Dictyostelium/citologia , Carpóforos/citologia , Carpóforos/fisiologia , Técnicas de Inativação de Genes , Complexo de Golgi/metabolismo , Anotação de Sequência Molecular , Dados de Sequência Molecular , Ligação Proteica/fisiologia , Domínios e Motivos de Interação entre Proteínas/fisiologia , Vacúolos/fisiologia , Equilíbrio Hidroeletrolítico/fisiologia
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA