Dosimetric effects of repeat computed tomography scan during radiotherapy planning in esophagus carcinoma.

Aim of Study: The aim was to assess the potential reduction in the doses to organs at risk (OARs) and target organ volume by doing replanning on repeat computed tomography (CT) scan during the 4th week of radiation therapy (RT). Materials and Methods: Twenty-four histologically proven patients of inoperable esophagus carcinoma were studied. All patients received induction chemotherapy followed by concurrent chemotherapy and radiotherapy. CT simulation with proper immobilization was done, and images were transferred to the treatment planning system. Delineation of target volumes and OARs was done, and two plans were generated for 60 Gy in 30 fractions and 40 Gy in 20 fractions with intensity-modulated RT keeping the doses to OARs within the tolerance limits. Replanning for 20 Gy in 10 fractions was done on repeat CT scan during the 4th week of radiotherapy treatment, and potential reduction in doses to OARs and target organ volume was assessed. Results: A total of 24 cases were analyzed for the adaptive plan with the coverage of the 95% prescription isodose for planning target volume. Statistical analysis was done by t-test. The difference in the doses received by the OARs was analyzed and was seen that due to re CT scan, the doses were reduced to the left lung V20 (mean 19.23 Gy vs. 17.35 Gy) and Dmean (mean 16.03 Gy vs. 14.25 Gy), right lung V20 (mean 18.38 Gy vs. 16.66 Gy) and Dmean (mean 15.70 Gy vs. 13.97 Gy), heart V25 (mean 38.72 Gy vs. 35.32 Gy) and Dmean (mean 26.40 Gy vs. 22.74 Gy), and spine 1% volume (mean 36.54 Gy vs. 33.39 Gy) and Dmax (mean 39.81 Gy vs. 34.34 Gy), gross tumor volume (GTV) (mean 67.37 cm 3 vs. 24.58 cm 3) and were all significantly smaller for the adaptive plan. Conclusion: By doing adaptive radiotherapy in the 4th week of treatment using repeat CT scan, along with the response evaluation, there is a significant reduction in the volume of GTV, and replanning of treatment on repeat CT scan also helps us in reducing doses to the OARs resulting in reduced toxicity.

Successful treatment of pulmonary artery aneurysms secondary to possible Behçet's disease.

Pulmonary artery aneurysm (PAA) secondary to Behçet's disease (BD) is a rare condition. The commonest presentation is hemoptysis, which can be fatal. Though the classical triad of recurrent oral and genital ulcers and relapsing iritis is present in most patients of BD, isolated pulmonary artery involvement termed as incomplete BD has been reported. Prompt diagnosis and immunosuppressive therapy can cause regression of aneurysm and prevent fatal hemoptysis. We report a case of PAA due to BD who presented with hemoptysis and responded to steroid therapy.

Isolation of troponin-like complex from bovine brain cortex.

A troponin-like complex has been isolated from bovine brain cortex. This tropinin-like complex, with brain tropomyosin, confers Ca2+ sensitivity to the actin-activated myosin adenosinetriphosphatase (ATP phosphohydrolase, EC 3.6.1.3). That is, the Mg2+-stimulated ATPase activity generated by the interaction of purified muscle actin with muscle myosin is inhibited in the absence of Ca2+ but not in the presence of Ca2+ as a result of the addition of both brain tropomyosin and troponin-like complex. The troponin-like complex contains three components, one of which is similar in molecular weight to the troponin-T of skeletal actomyosin.

Further characterization of brain actin by electron microscopy.

The physical state of actin in nerve ending preparations and its relationship to the membranes was studied at the ultrastructural level by negative staining with uranyl acetate before and after treatment with muscle heaving meromyosin (HMM). Actin prepared from synaptosomal or synaptic membrane preparations did not polymerize to fiber formation as readily as striated muscle actin under the same conditions. Treatment of these brain actin preparations with HMM, however, resulted in formation of fibers characteristically decorated with arrowheads which were quite similar to those formed with muscle actin. Treatment of the synaptosomal or synaptic membrane fractions themselves with HMM caused the formation of numerous decorated fibers although fibers were not evident before HMM treatment. This did not occur with the presynaptic vesicle fraction. The studies suggest that at least part of the actin is associated with synaptic membranes and is in a partially polymerized or non-polymerized state; polymerization can be induced by HMM.