Decrease In T2 Relaxation Times Research Articles

Targeted magnetic resonance imaging of Scavidin‐receptor in human umbilical vein endothelial cells in vitro

Current therapeutic approaches to treat cancer are often hampered by the lack of specificity of the drugs used for therapy. Scavidin, a novel fusion protein expressed on cell membranes, could be utilized for targeting of therapeutic molecules. Scavidin exploits the high binding affinity between avidin and biotin and is capable of mediating endocytosis of a bound ligand. In the current study we evaluated the efficiency of biotinylated ultrasmall superparamagnetic iron oxide (USPIO) particles in Scavidin-expressing human umbilical vein endothelial cell (HUVEC) cultures in vitro as a novel receptor-targeted magnetic resonance imaging contrast agent. Biotinylated USPIO (bUSPIO) were targeted to Scavidin adenovirus-transduced HUVECs in vitro. Scavidin expressing cells were capable of binding and mediating endocytosis of the bUSPIO in vitro, which led to a significant decrease in T2 relaxation times, and a loss of signal intensity in comparison to controls. The findings were confirmed with Prussian blue staining for iron and detection of Scavidin by bound biotinylated horseradish peroxidase. Our data shows that biotinylated ligands target specifically to Scavidin-expressing HUVEC in vitro. The utilization of Scavidin gene transfer ex vivo thus constitutes a platform for potential ligand delivery via cell therapy and time-independent imaging of biologic processes.

Studies of Peroxide Curing of cis-1,4-Polyisoprene/Diallyl Phthalate Blends by Spectroscopic Techniques

Abstract Peroxide curing of cis-1,4-polyisoprene/diallyl phthalate blends was studied by the analytical techniques of equilibrium swelling, differential scanning calorimetry (DSC), Fourier transform infrared (FT-IR), and solid-state nuclear magnetic resonance (NMR). Although the overall curing kinetics are controlled by the peroxide decomposition rate, the addition of a coagent into the rubber matrix catalyzes the curing reactions. The increase in peroxide and coagent concentrations in the blend results in a decrease in T2 relaxation times, which is caused by restricted segmental mobility due to the increase in crosslink density. It is suggested that phase separated coagent domains are chemically bound with the rubber matrix, providing the decrease in segmental mobility.

Graves ophthalmopathy: MR evaluation of 10-Gy versus 24-Gy irradiation combined with systemic corticosteroids.

To establish the most effective radiation dose for treatment of Graves ophthalmopathy (GO). A combination of 10 Gy (n = 15) or 24 Gy (n = 16) of radiation and corticosteroids was used to treat 31 patients with GO. Magnetic resonance (MR) images obtained before treatment showed swollen extraocular muscles with prolonged T2 relaxation times in all patients. Before therapy, T2 relaxation time of extraocular muscle was 79.6 msec (95% confidence interval, 76.3, 82.9) in the 24-Gy group and 77.4 msec (95% confidence interval, 74.6, 80.1) in the 10-Gy group (P = .32). After therapy, T2 relaxation time was 62.8 msec (95% confidence interval, 61.2, 64.4) in the 24-Gy group and 68.9 msec (95% confidence interval, 66.8, 71.1) in the 10-Gy group. In the 24-Gy group, there was a significant decrease in T2 relaxation times (P = .001) and clinical response to initial treatment was better. At 1- and 3-month follow-up, the resistance rate was lower in the 24-Gy group. In treatment of GO, 24 Gy of radiation is a more effective dose than 10 Gy when combined with systemic corticosteroids.

MR T2 Relaxation Time for the Assessment of Retrobulbar Inflammation in Graves' Ophthalmopathy

The results of 39 patients with severe Graves' ophthalmopathy (GO), who were monitored by magnetic resonance imaging (MRI) and tonography before and after combined immunosuppressive treatment with cyclosporine and corticosteroids, are presented. A correlation was found between the decrease in T2 relaxation time of the superior, medial, and inferior rectus muscle (p < 0.01) and the response to the immunosuppressive treatment. Muscle thickness and intraocular pressure showed less improvement (p < 0.05). The infiltrative eye signs improved partially in correlation with the T2 relaxation time. By distinguishing inflammation of the extraorbital muscles from fibrosis, the T2 relaxation time can help to select patients that benefit from immunosuppressive treatment as well as to monitor the therapeutic effect.

Radiation-induced uterine changes: MR imaging.

To assess the capability of magnetic resonance (MR) imaging to demonstrate postirradiation changes in the uterus, MR studies of 23 patients who had undergone radiation therapy were retrospectively examined and compared with those of 30 patients who had not undergone radiation therapy. MR findings were correlated with posthysterectomy histologic findings. In premenopausal women, radiation therapy induced (a) a decrease in uterine size demonstrable as early as 3 months after therapy ended; (b) a decrease in signal intensity of the myometrium on T2-predominant MR images, reflecting a significant decrease in T2 relaxation time, demonstrable as early as 1 month after therapy; (c) a decrease in thickness and signal intensity of the endometrium demonstrable on T2-predominant images 6 months after therapy; and (d) loss of uterine zonal anatomy as early as 3 months after therapy. In postmenopausal women, irradiation did not significantly alter the MR imaging appearance of the uterus. These postirradiation MR changes in both the premenopausal and postmenopausal uteri appeared similar to the changes ordinarily seen on MR images of the nonirradiated postmenopausal uterus.