In vivo comparison of DOTA based 68Ga-labelled bisphosphonates for bone imaging in non-tumour models.

Bone metastases are a class of cancerous metastases that result from the invasion of a tumor into bone. The solid mass which forms inside the bone is often associated with a constant dull ache and severe spikes in pain, which greatly reduce the quality of life of the patient. Numerous (99m)Tc-labeled bisphosphonate functionalised complexes are well established tracers for bone metastases imaging.

Measurement of protein synthesis: in vitro comparison of (68)Ga-DOTA-puromycin, [ (3)H]tyrosine, and 2-fluoro-[ (3)H]tyrosine.

Aim: Puromycin has played an important role in our understanding of the eukaryotic ribosome and protein synthesis. It has been known for more than 40 years that this antibiotic is a universal protein synthesis inhibitor that acts as a structural analog of an aminoacyl-transfer RNA (aa-tRNA) in eukaryotic ribosomes. Due to the role of enzymes and their synthesis in situations of need (DNA damage, e.

PET imaging of the impact of extracellular pH and MAP kinases on the p-glycoprotein (Pgp) activity.

The functional activity of p-glycoprotein (Pgp) can be increased in vitro by an extracellular acidosis via activation of MAP kinases (p38, ERK1/2). In order to study these effects in vivo a new (68)Ga-labeled PET tracer was developed which serves as a substrate of the Pgp and therefore indirectly mirrors the Pgp activity. For in vivo studies, experimental tumors were imaged under acidic conditions (inspiratory hypoxia, injection of lactic acid) and during inhibition of MAP kinases in a μ-PET system.

Imaging of protein synthesis: in vitro and in vivo evaluation of (44)Sc-DOTA-puromycin.

Purpose: The purpose of this study was to investigate whether (44)Sc-labeled puromycin can be utilized for imaging of protein synthesis in vivo.

Methods: For micro-positron emission tomographic (μPET) studies, 20-25 MBq of [(44)Sc]-DOTA-puromycin was administered to tumor-bearing rats, and animals were scanned for 1 h dynamically. Results were further validated by dissecting organs and tissues of the animals after the measurement and in vitro blocking experiments using puromycin or cycloheximide to block protein synthesis.

Assessing p-glycoprotein (Pgp) activity in vivo utilizing 68Ga-Schiff base complexes.

Purpose: The p-glycoprotein (Pgp) is the most prominent member of active drug transporters leading to a multidrug-resistant phenotype. For identification of tumors functionally overexpressing Pgp in vivo, non-invasive imaging techniques are needed.

Procedures: Six Schiff base compounds were synthesized and labeled with (68)Ge/(68)Ga generator-derived (68)Ga.

Activation of P-glycoprotein (Pgp)-mediated drug efflux by extracellular acidosis: in vivo imaging with 68Ga-labelled PET tracer.

Purpose: In vitro it has been shown that the functional activity of P-glycoprotein (Pgp), an important drug transporter responsible for multidrug resistance, can be strongly increased by extracellular acidosis. Here mitogen-activated protein kinases (MAPK) (p38, ERK1/2) seem to play an important role for signal transduction. However, it is unclear whether these effects are also relevant in vivo.