The treatment of primary and metastatic renal cell carcinoma (RCC) with image-guided stereotactic body radiation therapy (SBRT).

PURPOSE: Brain metastases from renal cell carcinoma (RCC) have been successfully treated with stereotactic radiosurgery (SRS). Metastases to extra-cranial sites may be treated with similar success using stereotactic body radiation therapy (SBRT), where image-guidance allows for the delivery of precise high-dose radiation in a few fractions. This paper reports the authors' initial experience with image-guided SBRT in treating primary and metastatic RCC. MATERIALS AND METHODS: The image-guided Brainlab Novalis stereotactic system was used. Fourteen patients with 23 extra-cranial metastatic RCC lesions (orbits, head and neck, lung, mediastinum, sternum, clavicle, scapula, humerus, rib, spine and abdominal wall) and two patients with biopsy-proven primary RCC (not surgical candidates) were treated with SBRT (24-40 Gy in 3-6 fractions over 1-2 weeks). All patients were immobilised in body cast or head and neck mask. Image-guidance was used for all fractions. PET/CT images were fused with simulation CT images to assist in target delineation and dose determination. SMART (simultaneous modulated accelerated radiation therapy) boost approach was adopted. 4D-CT was utilised to assess tumour/organ motion and assist in determining planning target volume margins. RESULTS: Median follow-up was nine months. Thirteen patients (93%) who received SBRT to extra-cranial metastases achieved symptomatic relief. Two patients had local progression, yielding a local control rate of 87%. In the two patients with primary RCC, tumour size remained unchanged but their pain improved, and their renal function was unchanged post SBRT. There were no significant treatment-related side effects. CONCLUSION: Image-guided SBRT provides excellent symptom palliation and local control without any significant toxicity. SBRT may represent a novel, non-invasive, nephron-sparing option for the treatment of primary RCC as well as extra-cranial metastatic RCC.

Fluorescence spectroscopy of 9-anthroyloxy fatty acids in solvents.

A series of anthroyloxy fatty acid (AF) fluorescent probes, with the anthroyloxy group covalently linked at various positions along the alkyl chain, were studied in solvents exhibiting a wide range of polarity and hydrogen-bond donor (Hd) and acceptor (Ha) ability. These probes were sensitive to the solvent polarity as reflected by the Stokes' shift observed in steady state fluorescence. As determined by multi-linear regression analysis of the observed Stokes' shift and solvent parameters, such as orientation polarizability (delta f), Hd and Ha of the solvents, all the probes were sensitive to the Hd of solvents but were not affected by the Ha of solvents except the 2-AF. Due to the proximity of the polar headgroup to the fluorophore, it appears that some intramolecular hydrogen-bonding is present in 2-AF, an interaction that is sensitive to the pH of the solvent, but is less sensitive to the Hd and Ha of the solvents. Fluorescence lifetimes measured by the multi-frequency phase-modulation technique in mixtures of hexane and ethanol reflect a modified Stern-Volmer behavior suggesting the second solvent, ethanol, specifically interacts with the probe, in part through collisional quenching. Also, the lifetime data were sensitive to very low concentrations of the second solvent (0-0.1%, by vol.). The results from this study provide insight into the intrinsic differences between the different AF positions that must be taken into consideration while investigating the dynamics of lipid bilayer systems. Moreover, this study illustrates the utility and resolving power of lifetime based measurements needed for the interpretation of heterogeneous biophysical environments.

Long-term structural changes in pH-sensitive hydrogels.

The long-term swelling properties of lightly cross-linked copolymer hydrogels consisting of methyl methacrylate (MMA) and N,N-dimethylaminoethyl methacrylamide (DMAA) were studied as a function of pH at 25 degrees C and 37 degrees C. In acidic pH regions, the swelling equilibria were found to be stable over 200 d. In alkaline pH environments, however, the 'equilibrium' swelling increases slowly with time. Gas chromatography of the supernatant shows that substantial methanol is produced, along with trace amounts of N,N-dimethylethylene diamine. Thus, the primary mechanism underlying the structural changes appears to be hydrolysis of ester groups in the MMA side-chains, with a much smaller contribution due to amidolysis of the DMAA side-chains. The implications of these structural changes for the application of this hydrogel, as well as other related hydrogels as long-term implantable biomaterials, are discussed.