Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 3 de 3
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
Neuropharmacology ; 117: 273-281, 2017 05 01.
Artigo em Inglês | MEDLINE | ID: mdl-28219717

RESUMO

Δ9-Tetrahydrocannabinol (THC) is the psychoactive component of the plant Cannabis sativa and acts as a partial agonist at cannabinoid type 1 and type 2 receptors in the brain. The goal of this study was to assess the effect of THC on the cerebral glucose uptake in the rat brain. 21 male Sprague Dawley rats (12-13 w) were examined and received five different doses of THC ranging from 0.01 to 1 mg/kg. For data acquisition a Focus 120 small animal PET scanner was used and 24.1-28.0 MBq of [18F]-fluoro-2-deoxy-d-glucose were injected. The data were acquired for 70 min and arterial blood samples were collected throughout the scan. THC, THC-OH and THC-COOH were determined at 55 min p.i. Nine volumes of interest were defined, and the cerebral glucose uptake was calculated for each brain region. Low blood THC levels of < 1 ng/ml (injected dose: ≤ 0.01 mg/kg) corresponded to an increased glucose uptake (6-30 %), particularly in the hypothalamus (p = 0.007), while blood THC levels > 10 ng/ml (injected dose: ≥ 0.05 mg/kg) coincided with a decreased glucose uptake (-2 to -22 %), especially in the cerebellar cortex (p = 0.008). The effective concentration in this region was estimated 2.4 ng/ml. This glucose PET study showed that stimulation of CB1 receptors by THC affects the glucose uptake in the rat brain, whereby the effect of THC is regionally different and dependent on dose - an effect that may be of relevance in behavioural studies.


Assuntos
Encéfalo/efeitos dos fármacos , Encéfalo/metabolismo , Agonistas de Receptores de Canabinoides/farmacologia , Dronabinol/farmacologia , Glucose/metabolismo , Psicotrópicos/farmacologia , Animais , Encéfalo/diagnóstico por imagem , Mapeamento Encefálico , Agonistas de Receptores de Canabinoides/sangue , Agonistas de Receptores de Canabinoides/farmacocinética , Cromatografia Líquida , Relação Dose-Resposta a Droga , Dronabinol/sangue , Dronabinol/farmacocinética , Fluordesoxiglucose F18 , Masculino , Tomografia por Emissão de Pósitrons , Psicotrópicos/sangue , Psicotrópicos/farmacocinética , Compostos Radiofarmacêuticos , Ratos Sprague-Dawley , Espectrometria de Massas em Tandem
2.
Recent Results Cancer Res ; 194: 395-423, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-22918772

RESUMO

Pulmonary imaging using ventilation/perfusion (V/P) single-photon emission tomography (V/P scan) with Tc-99m-labeled radiotracers is a well-established diagnostic tool for clinically suspected pulmonary embolism (PE). Ga-68 aerosol (Galligas) and Ga-68-labeled macroaggregated albumin (MAA) are potential tracers for positron emission tomography (PET) lung V/P imaging and could display an advantage over conventional V/P scans in terms of sensitivity and specificity. After radiochemical and animal studies, the clinical applicability of Ga-68 aerosol (Galligas) and Ga-68-labeled MAA was investigated in an exploratory study in patients with clinical suspicion of PE. PET scans were acquired using a 16-slice Gemini TF positron emission tomography/computed tomography (PET/CT) scanner. The acquisition protocol included low-dose computed tomography (CT) for attenuation correction (AC). Dosimetry calculations and continuative phantom measurements were performed. Structural analyses showed no modification of the particles due to the labeling process. In addition, in vitro experiments showed stability of Ga-68 MAA in various media. As expected, Ga-68-labeled human serum albumin microspheres (HSAM) were completely retained in the lung of the animals. In clinical use, PET lung ventilation and perfusion imaging using Ga-68 aerosol (Galligas) and Ga-68-labeled MAA was successful in all cases. In one case a clinically suspected PE could be detected and verified. The administered activity of Ga-68 aerosol (Galligas) and Ga-68-labeled MAA may be reduced by more than 50%, resulting in comparable radiation exposure to conventional V/P scans. In conclusion, Ga-68 aerosol (Galligas) and Ga-68-labeled MAA are efficient substitutes for clinical use and could be an interesting alternative with high accuracy for lung V/P imaging with Tc-99m-labeled radiotracers, especially in times of Mo-99 shortages and increasing use and spread of PET/CT scanners and Ga-68 generators, respectively.


Assuntos
Radioisótopos de Gálio , Tomografia por Emissão de Pósitrons/métodos , Relação Ventilação-Perfusão , Aerossóis , Idoso , Idoso de 80 Anos ou mais , Animais , Feminino , Humanos , Masculino , Microesferas , Radiometria , Ratos , Ratos Sprague-Dawley , Albumina Sérica
3.
Nucl Med Biol ; 39(7): 993-9, 2012 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-22633217

RESUMO

PURPOSE: Bone metastases are a serious aggravation for patients suffering from cancer. Therefore, early recognition of bone metastases is of great interest for further treatment of patients. Bisphosphonates are widely used for scintigraphy of bone lesions with (99m)Tc. Using the (68)Ge/(68)Ga generator together with a macroyclic bisphosphonate a comparable PET-tracer comes into focus. PROCEDURES: The bisphosphonate DOTA-conjugated ligand BPAMD was labelled with (68)Ga. [(68)Ga]BPAMD was evaluated in vitro concerning binding to hydroxyapatite and stability. The tracer's in vivo accumulation was determined on healthy rats and bone metastases bearing animals by µ-PET. RESULTS: BPAMD was labelled efficiently with (68)Ga after 10 min at 100°C. [(68)Ga]BPAMD showed high in vitro stability within 3h and high binding to hydroxyapatite. Consequently, µ-PET experiments revealed high accumulation of [(68)Ga]BPAMD in regions of pronounced remodelling activity like bone metastases. CONCLUSIONS: (68)Ga BPAMD reveals great potential for diagnosis of bone metastases via PET/CT. The straight forward (68)Ga-labelling could be transferred to a kit-preparation of a cyclotron-independent PET tracer instantaneously available in many clinical sites using the (68)Ge/(68)Ga generator.


Assuntos
Neoplasias Ósseas/diagnóstico por imagem , Neoplasias Ósseas/secundário , Difosfonatos/química , Elétrons , Compostos Heterocíclicos com 1 Anel/química , Tomografia por Emissão de Pósitrons/métodos , Animais , Linhagem Celular Tumoral , Difosfonatos/metabolismo , Durapatita/metabolismo , Radioisótopos de Gálio , Compostos Heterocíclicos com 1 Anel/metabolismo , Masculino , Radioquímica , Ratos
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...