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1.
Contrast Media Mol Imaging ; 2018: 1292746, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30026674

RESUMO

Introductions: [N-methyl-C-11]α-Methylaminoisobutyric acid (MeAIB) is an artificial amino acid radiotracer used for PET study, which is metabolically stable in vivo. In addition, MeAIB is transported by system A neutral amino acid transport, which is observed ubiquitously in all types of mammalian cells. It has already been shown that MeAIB-PET is useful for malignant lymphoma, head and neck cancers, and lung tumors. However, there have been no reports evaluating the usefulness of MeAIB-PET in the diagnosis of brain tumors. The purpose of this study is to investigate the efficacy of system A amino acid transport PET imaging, MeAIB-PET, in clinical brain tumor diagnosis compared to [S-methyl-C-11]-L-methionine (MET)-PET. Methods: Thirty-one consecutive patients (male: 16, female: 15), who were suspected of having brain tumors, received both MeAIB-PET and MET-PET within a 2-week interval. All patients were classified into two groups: Group A as a benign group, which included patients who were diagnosed as low-grade astrocytoma, grade II or less, or other low-grade astrocytoma (n=12) and Group B as a malignant group, which included patients who were diagnosed as anaplastic astrocytoma, glioblastoma multiforme (GBM), or recurrent GBM despite prior surgery or chemoradiotherapy (n=19). PET imaging was performed 20 min after the IV injection of MeAIB and MET, respectively. Semiquantitative analyses of MeAIB and MET uptake using SUVmax and tumor-to-contralateral normal brain tissue (T/N) ratio were evaluated to compare these PET images. ROC analyses for the diagnostic accuracy of MeAIB-PET and MET-PET were also calculated. Results: In MeAIB-PET imaging, the SUVmax was 1.20 ± 1.29 for the benign group and 2.94 ± 1.22 for the malignant group (p < 0.005), and the T/N ratio was 3.77 ± 2.39 for the benign group and 16.83 ± 2.39 for the malignant group (p < 0.001). In MET-PET, the SUVmax was 3.01 ± 0.94 for the benign group and 4.72 ± 1.61 for the malignant group (p < 0.005), and the T/N ratio was 2.64 ± 1.40 for the benign group and 3.21 ± 1.14 for the malignant group (n.s.). For the analysis using the T/N ratio, there was a significant difference between the benign and malignant groups with MeAIB-PET with p < 0.001. The result of ROC analysis using the T/N ratio indicated a better diagnosis accuracy for MeAIB-PET for brain tumors than MET-PET (p < 0.01). Conclusions: MeAIB, a system A amino acid transport-specific radiolabeled agents, could provide better assessments for detecting malignant type brain tumors. In a differential diagnosis between low-grade and high-grade astrocytoma, MeAIB-PET is a useful diagnostic imaging tool, especially in evaluations using the T/N ratio. Clinical trial registration: This trial was registered with UMIN000032498.


Assuntos
Astrocitoma/diagnóstico por imagem , Neoplasias Encefálicas/diagnóstico , Tomografia por Emissão de Pósitrons/métodos , Compostos Radiofarmacêuticos/normas , Adolescente , Adulto , Idoso , Sistema A de Transporte de Aminoácidos , Neoplasias Encefálicas/diagnóstico por imagem , Criança , Pré-Escolar , Diagnóstico Diferencial , Feminino , Humanos , Masculino , Metionina/farmacocinética , Metionina/normas , Pessoa de Meia-Idade , Curva ROC , Compostos Radiofarmacêuticos/farmacocinética , Adulto Jovem , beta-Alanina/análogos & derivados , beta-Alanina/farmacocinética , beta-Alanina/normas
2.
Orig Life Evol Biosph ; 48(2): 201-211, 2018 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-29796877

RESUMO

A one-pot method was developed for the preparation of a series of ß-alanine standards of moderate size (2 to ≥12 residues) for studies concerning the prebiotic origins of peptides. The one-pot synthesis involved two sequential reactions: (1) dry-down self-condensation of ß-alanine methyl ester, yielding ß-alanine peptide methyl ester oligomers, and (2) subsequent hydrolysis of ß-alanine peptide methyl ester oligomers, producing a series of ß-alanine peptide standards. These standards were then spiked into a model prebiotic product mixture to confirm by HPLC the formation of ß-alanine peptides under plausible reaction conditions. The simplicity of this approach suggests it can be used to prepare a variety of ß-peptide standards for investigating differences between α- and ß-peptides in the context of prebiotic chemistry.


Assuntos
Origem da Vida , Peptídeos/síntese química , beta-Alanina/normas , Cromatografia Líquida de Alta Pressão , Hidrólise , beta-Alanina/química
3.
Wien Klin Wochenschr ; 126(17-18): 503-8, 2014 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-25138549

RESUMO

Dabigatran, a direct thrombin inhibitor, is licensed for the prevention of venous thromboembolism after knee and hip replacement, the prevention of stroke and systemic embolism in patients with non-valvular atrial fibrillation and for the treatment of acute venous thromboembolism. As dabigatran has a favourable benefit-risk profile, it is being increasingly used. Dabigatran differs from vitamin K antagonists as regards its pharmacological characteristics and its impact on certain laboratory tests, and also in the lack of a direct antagonist that can reverse dabigatran-induced anticoagulation. In emergency settings such as acute bleeding, emergency surgery, acute coronary syndrome, thrombolysis for ischaemic stroke or overdosing, specific strategies are required. A working group of experts from various disciplines has developed strategies for the management of dabigatran-treated patients in emergency settings.


Assuntos
Artroplastia de Substituição/efeitos adversos , Benzimidazóis/administração & dosagem , Benzimidazóis/efeitos adversos , Hemorragia/induzido quimicamente , Guias de Prática Clínica como Assunto , Tromboembolia Venosa/etiologia , Tromboembolia Venosa/prevenção & controle , beta-Alanina/análogos & derivados , Antitrombinas/administração & dosagem , Antitrombinas/efeitos adversos , Artroplastia de Substituição/normas , Áustria , Benzimidazóis/normas , Dabigatrana , Hemorragia/prevenção & controle , Humanos , beta-Alanina/administração & dosagem , beta-Alanina/efeitos adversos , beta-Alanina/normas
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