Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 14 de 14
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
2.
J Vasc Interv Radiol ; 31(10): 1517-1528.e2, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32948386

RESUMO

PURPOSE: To evaluate relationships between immediate venographic results and clinical outcomes of pharmacomechanical catheter-directed thrombolysis (PCDT). MATERIALS AND METHODS: Venograms from 317 patients with acute proximal deep vein thrombosis (DVT) who received PCDT in a multicenter randomized trial were reviewed. Quantitative thrombus resolution was assessed by independent readers using a modified Marder scale. The physician operators recorded their visual assessments of thrombus regression and venous flow. These immediate post-procedure results were correlated with patient outcomes at 1, 12, and 24 months. RESULTS: PCDT produced substantial thrombus removal (P < .001 for pre-PCDT vs. post-PCDT thrombus scores in all segments). At procedure end, spontaneous venous flow was present in 99% of iliofemoral venous segments and in 89% of femoral-popliteal venous segments. For the overall proximal DVT population, and for the femoral-popliteal DVT subgroup, post-PCDT thrombus volume did not correlate with 1-month or 24-month outcomes. For the iliofemoral DVT subgroup, over 1 and 24 months, symptom severity scores were higher (worse), and venous disease-specific quality of life (QOL) scores were lower (worse) in patients with greater post-PCDT thrombus volume, with the difference reaching statistical significance for the 24-month Villalta post-thrombotic syndrome (PTS) severity score (P = .0098). Post-PCDT thrombus volume did not correlate with 12-month valvular reflux. CONCLUSIONS: PCDT successfully removes thrombus in acute proximal DVT. However, the residual thrombus burden at procedure end does not correlate with the occurrence of PTS during the subsequent 24 months. In iliofemoral DVT, lower residual thrombus burden correlates with reduced PTS severity and possibly also with improved venous QOL and fewer early symptoms.


Assuntos
Veia Femoral , Fibrinolíticos/administração & dosagem , Veia Ilíaca , Veia Poplítea , Terapia Trombolítica , Ativador de Plasminogênio Tecidual/administração & dosagem , Trombose Venosa/terapia , Adolescente , Adulto , Idoso , Feminino , Veia Femoral/diagnóstico por imagem , Fibrinolíticos/efeitos adversos , Humanos , Veia Ilíaca/diagnóstico por imagem , Masculino , Pessoa de Meia-Idade , Flebografia , Veia Poplítea/diagnóstico por imagem , Síndrome Pós-Trombótica/etiologia , Terapia Trombolítica/efeitos adversos , Fatores de Tempo , Ativador de Plasminogênio Tecidual/efeitos adversos , Resultado do Tratamento , Estados Unidos , Trombose Venosa/complicações , Trombose Venosa/diagnóstico por imagem , Adulto Jovem
3.
J Am Coll Radiol ; 17(5S): S315-S322, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32370975

RESUMO

This publication includes the appropriate imaging modalities to assess suspected deep vein thrombosis in the upper extremities. Ultrasound duplex Doppler is the most appropriate imaging modality to assess upper-extremity deep vein thrombosis. It is a noninvasive test, which can be performed at the bedside and used for serial evaluations. Ultrasound can also directly identify thrombus by visualizing echogenic material in the vein and by lack of compression of the vein walls from manual external pressure. It can indirectly identify thrombus from altered blood-flow patterns. It is most appropriate in the evaluation of veins peripheral to the brachiocephalic vein. CT venography and MR venography are not first-line imaging tests, but are appropriate to assess the central venous structures, or to assess the full range of venous structures from the hand to the right atrium. Catheter venography is appropriate if therapy is required. Radionuclide venography and chest radiography are usually not appropriate to assess upper-extremity deep vein thrombosis. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

4.
J Am Coll Radiol ; 15(11S): S413-S417, 2018 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-30392609

RESUMO

Suspected lower extremity deep venous thrombosis is a common clinical scenario which providers seek a reliable test to guide management. The importance of confidently making this diagnosis lies in the 50% to 60% risk of pulmonary embolism with untreated deep vein thrombosis and subsequent mortality of 25% to 30%, balanced with the risks of anticoagulation. The ACR Appropriateness Criteria Expert Panel on Vascular Imaging reviews the current literature regarding lower extremity deep venous thrombosis and compared various imaging modalities including ultrasound, MR venography, CT venography, and catheter venography. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.


Assuntos
Extremidade Inferior/irrigação sanguínea , Trombose Venosa/diagnóstico por imagem , Diagnóstico Diferencial , Medicina Baseada em Evidências , Humanos , Sociedades Médicas , Estados Unidos
5.
J Am Coll Radiol ; 14(5S): S307-S313, 2017 May.
Artigo em Inglês | MEDLINE | ID: mdl-28473087

RESUMO

Acute limb ischemia (ALI) requires urgent diagnosis and treatment to prevent limb loss. Invasive digital subtraction arteriography (DSA) is the gold standard for diagnosing ALI. DSA is the only diagnostic modality that permits simultaneous treatment of acute arterial occlusion. Noninvasive imaging with MRA or CT angiography may also be appropriate before treatment, especially when the diagnosis of ALI is in doubt or where DSA is unavailable. Other imaging and noninvasive physiologic tests may prove important for longer term management but are less recommended in the acute setting. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.


Assuntos
Angiografia Digital/métodos , Hipotermia/diagnóstico por imagem , Isquemia/diagnóstico por imagem , Perna (Membro)/irrigação sanguínea , Doença Aguda , Angiografia , Angiografia por Tomografia Computadorizada , Humanos , Hipotermia/etiologia , Perna (Membro)/diagnóstico por imagem , Angiografia por Ressonância Magnética , Dor , Radiologia , Sociedades Médicas , Estados Unidos
7.
J Am Coll Radiol ; 8(8): 556-62, 2011 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-21807349

RESUMO

The 2010 RAD-AID Conference on International Radiology for Developing Countries was a multidisciplinary meeting to discuss data, experiences, and models pertaining to radiology in the developing world, where widespread shortages of imaging services reduce health care quality. The theme of this year's conference was sustainability, with a focus on establishing and maintaining imaging services in resource-limited regions. Conference presenters and participants identified 4 important components of sustainability: (1) sustainable financing models for radiology development, (2) integration of radiology and public health, (3) sustainable clinical models and technology solutions for resource-limited regions, and (4) education and training of both developing and developed world health care personnel.


Assuntos
Países em Desenvolvimento , Diagnóstico por Imagem/normas , Diagnóstico por Imagem/tendências , Agências Internacionais , Radiologia , Congressos como Assunto , Humanos , Saúde Pública , Radiologia/tendências
8.
Acad Radiol ; 18(6): 782-91, 2011 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-21458308

RESUMO

RATIONALE AND OBJECTIVES: To measure perceptions of radiology residents regarding the imaging needs of the developing world and the potential role of an organized global health imaging curriculum during residency training. MATERIALS AND METHODS: An electronic survey was created and then distributed to residents in accredited US radiology residency. RESULTS: Two hundred ninety-four residents responded to the survey. A majority (61%) planned to pursue future international medical aid work, even though a similar proportion (59%) believed that they would be ill-prepared with their current training to pursue this career goal. The vast majority (91%) of respondents stated that their residency program offers no opportunities to participate in global health imaging experiences. Most surveyed residents felt that an organized global health imaging curriculum would improve understanding of basic disease processes (87%) and cost-conscious care (82%), prepare residents for lifelong involvement in global health (80%), and increase interpretative skills in basic radiology modalities (73%). If such a curriculum were available, most (62%) of surveyed residents stated that they would be likely or very likely to participate. Many (58%) believed the availability of such a program would have influenced their choice of residency program; a similar proportion of residents (75%) believed that the availability of a global health imaging curriculum would increase recruitment to the field of radiology. CONCLUSION: Many radiology residents are motivated to acquire global health imaging experience, with most survey respondents planning to participate in global health initiatives. These data demonstrate an imbalance between the level of resident interest and the availability of global health imaging opportunities, and support the need for discussion on how to implement global health imaging training within radiology residency programs.


Assuntos
Atitude do Pessoal de Saúde , Países em Desenvolvimento , Educação de Pós-Graduação em Medicina/métodos , Saúde Global , Internato e Residência , Radiologia/educação , Distribuição de Qui-Quadrado , Currículo , Humanos , Inquéritos e Questionários , Estados Unidos
9.
J Am Coll Radiol ; 7(7): 495-500, 2010 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-20630383

RESUMO

The RAD-AID Conference on International Radiology for Developing Countries was an assembly of individuals and organizations interested in improving access to medical imaging services in developing countries where the availability of radiology has been inadequate for both patient care and public health programs. The purpose of the meeting was to discuss data, experiences, and models pertaining to radiology in the developing world and to evaluate potential opportunities for future collaboration. Conference participants included radiologists, technologists, faculty members of academic medical institutions, and leadership of nongovernmental organizations involved in international health care and social entrepreneurship. Four main themes from the conference are presented in this white paper as important factors for the implementation and optimization of radiology in the developing world: (1) ensuring the economic sustainability of radiologic services through financial and administrative training support of health care personnel; (2) designing, testing, and deploying clinical strategies adapted for regions with limited resources; (3) structuring and improving the role of American radiology residents interested in global health service projects; and (4) implementing information technology models to support digital imaging in the developing world.


Assuntos
Países em Desenvolvimento , Cooperação Internacional , Radiologia/economia , Radiologia/normas , Diagnóstico por Imagem , Humanos , Modelos Teóricos , Radiologia/educação
10.
J Membr Biol ; 230(1): 35-47, 2009 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-19609824

RESUMO

The hyperpolarization-activated cyclic nucleotide-modulated channel gene family (HCN1-4) encodes the membrane depolarizing current that underlies pacemaking. Although the topology of HCN resembles K(v) channels, much less is known about their structure-function correlation. Previously, we identified several pore residues in the S5-P linker and P-loop that are externally accessible and/or influence HCN gating, and proposed an evolutionarily conserved pore-to-gate mechanism. Here we sought dynamic evidence by assessing the functional consequences of Cys-scanning substitutions in the unexplored P-S6 linker (residues 352-359), the HCN1-R background (that is, resistant to sulfhydryl-reactive agents). None of A352C, Q353C, A354C, P355C, V356C, S357C, M358C, or S359C produced functional currents; the loss-of-function of Q353C, A354C, S357C, and M358C could be rescued by the reducing agent dithiothreitol. Q353C, A354C, and S357C, but not M358C and HCN1-R, were sensitive to Cd(2+) blockade (IC(50) = 3-12 microM vs. >1 mM). External application of the positively charged covalent sulfhydryl modifier MTSET irreversibly reduced I (-140mV) of Q353C and A354C to 27.9 +/- 3.4% and 58.2 +/- 13.1% of the control, respectively, and caused significant steady-state activation shifts (DeltaV(1/2) = -21.1 +/- 1.6 for Q353C and -10.0 +/- 2.9 mV for A354C). Interestingly, MTSET reactivity was also state dependent. MTSET, however, affected neither S357C nor M358C, indicating site specificity. Collectively, we have identified novel P-S6 residues whose extracellular accessibility was sterically and state dependent and have provided the first functional evidence consistent with a dynamic HCN pore-to-gate model.


Assuntos
Canais de Cátion Regulados por Nucleotídeos Cíclicos/química , Canais de Cátion Regulados por Nucleotídeos Cíclicos/metabolismo , Animais , Western Blotting , Cádmio/farmacologia , Canais de Cátion Regulados por Nucleotídeos Cíclicos/efeitos dos fármacos , Canais de Cátion Regulados por Nucleotídeos Cíclicos/genética , Cisteína/química , Cisteína/genética , Ditiotreitol/farmacologia , Eletrofisiologia , Camundongos , Modelos Biológicos , Oócitos , Relação Estrutura-Atividade , Xenopus
12.
Cardiovasc Res ; 67(2): 263-73, 2005 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-16005302

RESUMO

OBJECTIVE: I(f), encoded by the hyperpolarization-activated, cyclic nucleotide-modulated (HCN) channel gene family, modulates cardiac pacing. During cardiac pacing, changes in membrane potential are rapid, preventing the very slow HCN channels from reaching equilibrium. Here, we examined the properties of HCN channels under non-equilibrium conditions to shed insight into how different HCN isoforms contribute to cardiac pacing. METHODS AND RESULTS: HCN1, 2 and 4 channels were heterologously expressed in Xenopus laevis oocytes or mammalian Cos7 cells and subjected to voltage clamp. We found that HCN1 channel activation (V1/2) depended strongly on the holding potential (V(H)) for short (100 ms; V1/2=-118 mV, -78 mV and -19 mV for V(H)= +70, -75 and -140 mV, respectively, in Xenopus oocytes) but not long (300-ms) test-pulses, hinting that shifts of V1/2 under non-equilibrium conditions may alter the impact of I(f) in different phases of the cardiac circle. Consistent with this notion, when a train of SA nodal-like action potentials was applied in voltage-clamp experiments, HCN1 exhibited pronounced current-voltage (IV)-hysteresis. Using computational modeling, we demonstrate that the intrinsically sluggish HCN1 activation kinetics underlie their IV-hysteretic behavior and do not hinder the ability to modulate cardiac pacing. By contrast, HCN4 did not exhibit IV-hysteresis. This difference can be attributed to the relatively large activation time constant and markedly delayed onsets of time-dependent HCN4 currents. Indeed, HCN2 channels, which have intermediate activation time constants and delays, displayed and intermediate hysteretic phenotype. CONCLUSION: We conclude that non-equilibrium properties of HCN channels contribute to cardiac pacing. These results provide insight for tuning the firing rate of endogenous and induced pacemakers using engineered HCN constructs with distinct gating phenotypes.


Assuntos
Simulação por Computador , Sistema de Condução Cardíaco/fisiologia , Ativação do Canal Iônico/fisiologia , Canais Iônicos/metabolismo , Modelos Cardiovasculares , Potenciais de Ação , Animais , Células COS , Chlorocebus aethiops , Canais de Cátion Regulados por Nucleotídeos Cíclicos , Elasticidade , Feminino , Humanos , Canais Disparados por Nucleotídeos Cíclicos Ativados por Hiperpolarização , Canais Iônicos/genética , Proteínas Musculares/genética , Proteínas Musculares/metabolismo , Oócitos , Técnicas de Patch-Clamp , Canais de Potássio , Isoformas de Proteínas/genética , Isoformas de Proteínas/metabolismo , Xenopus
13.
Biochem Biophys Res Commun ; 327(4): 1131-42, 2005 Feb 25.
Artigo em Inglês | MEDLINE | ID: mdl-15652514

RESUMO

Although ample evidence suggests the presence of an intracellular activation gate in HCN (pacemaker) channels, mutations in the outer pore can alter gating properties. Here we investigated the role of the outer pore residue A354 in HCN1 gating by systematically converting it to the equivalent residues (T, Y, and F) found in K(+)-channels. A354T negatively shifted steady-state activation (DeltaV(1/2) approximately -25 mV), decelerated gating kinetics (by up to 8-fold), and abolished the effects of external ions on gating. A354Y and A354F did not yield functional currents when expressed alone, although immunofluorescence microscopy indicated the presence of these channel proteins on the membrane surface. Currents recorded after co-expressing A354Y with WT HCN1 were reduced in amplitude (relative to WT alone) and had changes in gating similar to those of A354T. We conclude that the pore variant at position 354 contributes to gating but not permeation, and that the HCN outer pore may be involved in gating via a pore-to-gate coupling mechanism.


Assuntos
Substituição de Aminoácidos/genética , Permeabilidade da Membrana Celular , Ativação do Canal Iônico/fisiologia , Canais Iônicos/genética , Canais Iônicos/metabolismo , Alanina/genética , Alanina/metabolismo , Sequência de Aminoácidos , Animais , Canais de Cátion Regulados por Nucleotídeos Cíclicos , Expressão Gênica , Canais Disparados por Nucleotídeos Cíclicos Ativados por Hiperpolarização , Canais Iônicos/química , Cinética , Dados de Sequência Molecular , Mutagênese Sítio-Dirigida , Oócitos/metabolismo , Canais de Potássio , Subunidades Proteicas/química , Subunidades Proteicas/genética , Subunidades Proteicas/metabolismo , Alinhamento de Sequência , Xenopus laevis
14.
J Physiol ; 547(Pt 2): 349-56, 2003 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-12562911

RESUMO

Hyperpolarization-activated cyclic-nucleotide-gated (HCN) channels modulate the firing rates of neuronal and cardiac pacemaker cells. HCN channels resemble voltage-gated K+ channels structurally, but much less is known about their structure-function correlation. Although modulation of K+ channel gating by external K+ is a well-known phenomenon, such a link has not been established for HCN channels. Here we examined the effects of external permeant (K+, Na+ and Li+) and non-permeant (NMG+) ions on HCN1 and HCN2 gating. Substituting 64 of 96 mM external K+ with Na+, Li+ or NMG+ positively shifted steady-state activation (approximately 13 mV), and preferentially slowed activation of HCN1. Mutating the pore variant C-terminal to the GYG motif in HCN1, A352, to the analogous conserved Asp in K+ channels or Arg in HCN2 produced a significant hyperpolarizing activation shift (by 5-15 mV), slowed gating kinetics (up to 6-fold), and abolished or attenuated gating responses to external K+. Whereas Na+, Li+ and NMG+ substitutions produced depolarizing activation shifts of HCN2 similar to those of HCN1, deactivation but not activation of HCN2 was exclusively decelerated. We conclude that gating and permeation of HCN channels are coupled, and that modulation of this 'pore-to-gate' coupling by external K+ is isoform-specific.


Assuntos
Canais Iônicos/efeitos dos fármacos , Proteínas Musculares/efeitos dos fármacos , Potássio/farmacologia , Motivos de Aminoácidos , Animais , Arginina , Ácido Aspártico , Sequência Consenso , Canais de Cátion Regulados por Nucleotídeos Cíclicos , Glicina , Canais Disparados por Nucleotídeos Cíclicos Ativados por Hiperpolarização , Ativação do Canal Iônico , Canais Iônicos/genética , Canais Iônicos/metabolismo , Cinética , Lítio/farmacologia , Meglumina/farmacologia , Proteínas Musculares/genética , Proteínas Musculares/metabolismo , Mutação , Oócitos , Canais de Potássio , Sódio/farmacologia , Relação Estrutura-Atividade , Tirosina , Xenopus
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA