Dosimetric differences between cesium-131 and iodine-125 brachytherapy for the treatment of resected brain metastases

Purpose: To compare treatment plans and evaluate dosimetric characteristics of permanent cesium-131 (131Cs) vs. iodine-125 (125I) implants used in brain brachytherapy. Material and methods: Twenty-four patients with 131Cs implants from a prospective phase I/II trial were re-planned with 125I implants. In order to evaluate the volume of brain tissue exposed to radiation therapy (RT), the dose volume histogram was generated for both radioisotopes. To evaluate the dosimetric differences of the two radioisotopes we compared homogeneity (HI) and conformity indices (CI), and dose covering 100% (D100), 90% (D90), 80% (D80), and 50% (D50) of the clinical target volume (CTV). Results: At the 100%, 90%, 80%, and 50% isodose lines, the 131Cs plans exposed less mean volume of brain tissue than the 125I plans (p \u3c 0.001). The D100, D90, D80, and D50 were smaller for 131Cs (p \u3c 0.001). The HI and CI for 131Cs vs. 125I were 19.71 vs. 29.04 and 1.31 vs. 1.92, respectively (p \u3c 0.001). Conclusions: Compared to 125I, 131Cs exposed smaller volumes of brain tissue to equivalent doses of radiation and delivered lower radiation doses to equivalent volumes of the CTV. 131Cs exhibited a higher HI, indicating increased uniformity of doses within the CTV. Lastly, 131Cs presented a CI closer to 1, indicating that the total volume receiving the prescription dose was closer to the desired CTV volume. These results suggest that 131Cs is dosimetrically superior to 125I and may explain the reason for the 0% incidence of radiation necrosis (RN) in our previously published prospective study using 131Cs

JPET#53181 ROLE OF THE NITRIC OXIDE SYNTHASE ISOFORMS DURING MORPHINE- INDUCED HYPERTHERMIA IN RATS

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Intrahypothalamic Injection of the HIV-1 Envelope Glycoprotein Induces Fever via Interaction with the Chemokine System

Wasting syndrome is a common complication of HIV infection and is marked by progressive weight loss and weakness, often associated with fever. The mechanisms involved in the pathogenesis of these syndromes are not well defined, and neither are the brain areas involved. The present study tests a new hypothesis: that the preoptic anterior hypothalamus (POAH), the main brain area for thermoregulation and fever, has a role in the pathogenesis of fever induced by glycoprotein 120 (gp120), the surface envelope protein used by the HIV to gain access into immune cells, and that the CXC chemokine receptors (CXCR4) that serve as a coreceptor for HIV entry mediate the effect. A sterilized stainless steel C313G cannula guide was implanted into the POAH, and a biotelemetry system was used to monitor the body temperature (Tb) changes. The administration of gp120 into the POAH induced fever in a dose-dependent manner. To demonstrate possible links between the gp120 and CXCR4 in generating the fever, we pretreated the rats with 1,1′-[1,4-phenylenebis(methylene)]bis[1,4,8,11-tetraazacyclotetradecane] octohydrobromide dihydrate (AMD 3100), an antagonist of stromal cell-derived growth factor (SDF)-1α/CXCL12, acting at its receptor, CXCR4, 30 min before administration of gp120. AMD 3100 significantly reduced the gp120-induced fever. The present studies show that the presence of HIV-1 envelope glycoprotein gp120 in the POAH provokes fever via interaction CXCR4 pathway