Radiological Hazards of Iodine-131 Therapy

Once iodine-131 is administered to a patient undergoing therapy, the individual becomes a significant source of radiation exposure to attending staff and other patients. The patient also becomes a source of radioactive contamination since much of the administered radioiodine is gradually eliminated via urinary excretion, exhaled air, and perspiration. Duke University Medical Center uses iodine-131 for three different types of cancer treatments: sodium iodide for thyroid carcinoma, monoclonal antibodies for neoplastic meningitis, and metaiodobenzylguanidine (MiBG) for neuroendocrine tumors. The primary focus of this study was to assess the radiological hazards to the medical staff attending these isolated patients and to members of the general public near the patient rooms. In addition, data from this study were used to design special rooms to house patients undergoing radioiodine therapy. The amount of radioiodine administered to the 17 patients in this study ranged from 2.2 GBq (60 mCi) to 11.2 GBq (303 mCi). Exposure rates were measured using an ion chamber at several locations within patient rooms as well as in the hallway and accessible adjacent rooms. Measurements taken within patient rooms ranged from 4.1 x 10[-8] C kg[-1] hr[-1] (0.16 mR hr[-1]) to 1.7 x 10[-5] C kg[-1] hr[-1] (67 mR hr[-1]). Exposure rates ranged from 8.3 x 10[-9] C kg[-1] hr[-1] (0.032 mR hr[-1]) to 4.1 x 10[-7] C kg[-1] hr[-1] (1.6 mR hr[-1]) in the hallways and accessible adjacent rooms. Thermoluminescent dosimeters (TLDs) mounted on the walls, floor, and ceiling of patient rooms were used to determine accumulated dose equivalents for the duration of the patient treatments. The TLD results ranged from 0.20 mSv (20 mrem) to 19.5 mSv (1,950 mrem). Using a portable GM detector, contamination surveys were performed in patient rooms after the patients were discharged from the hospital. Detected contamination levels ranged from 100 c min[-1] to 240,000 c min[-1]. Air sampling was also performed to determine the concentration of radioiodine in the air and to evaluate the necessity for "negative pressure" patient therapy rooms. Exposure rate measurements and dose equivalent measurements suggest that a potential hazard exists for both the attending medical staff and the general public. Dedicating two new lead lined rooms for iodine-131 therapies would greatly reduce hazards to the general public as well as ease the patient room decontamination process for the radiation safety staff. Air sampling results proved to be inconclusive since activity was seen throughout the air sampling units.Master of Science in Public Healt

Phase II Clinical Trial of Robotic Stereotactic Body Radiosurgery for Metastatic Gynecologic Malignancies

Background: Recurrent gynecologic cancers are often difficult to manage without significant morbidity. We conducted a phase II study to assess the safety and the efficacy of ablative robotic stereotactic body radiosurgery (SBRT) in women with metastatic gynecologic cancers. Methods: A total of 50 patients with recurrent gynecologic cancer who had single or multiple (≤4) metastases underwent robotic-armed Cyberknife SBRT (24Gy/3 daily doses). Toxicities were graded prospectively by common toxicity criteria for adverse events (version 4.0). SBRT target responses were recorded following RECIST criteria (version 1.0). Rates of clinical benefit for SBRT and non-radiosurgical disease relapse were calculated. Disease-free and overall survivals were estimated by the Kaplan–Meier method and the Cox proportional hazards model was used to control for prognostic variables. Findings: SBRT was safely delivered, with 49 (98%) of 50 patients completing three prescribed fractions. The most frequent grade 2 or higher adverse events attributed to SBRT included fatigue (16%), nausea (8%), and diarrhea (4%). One (2%) grade four hyperbilirubinemia occurred. SBRT target response was 96% (48 of 50 patients). A 6-month clinical benefit was recorded in 34 [68% (95% CI, 53.2, 80.1)] patients. No SBRT targeted disease progressed. Non-radiosurgical disease relapse occurred in 31 (62%) patients. Median disease-free survival was 7.8 months (95% CI, 4.0, 11.6). Median overall survival was 20.2 months (95% CI, 10.9, 29.5). Interpretation: SBRT safely controlled metastatic gynecologic cancer targets. Given an observed high rate of non-radiosurgical disease relapse, a phase I trial assessing co-administration of SBRT and cytotoxic chemotherapy is underway. Funding: Case Comprehensive Cancer Center

Membrane and synaptic defects leading to neurodegeneration in Adar mutant Drosophila are rescued by increased autophagy

BackgroundIn fly brains, the Drosophila Adar (adenosine deaminase acting on RNA) enzyme edits hundreds of transcripts to generate edited isoforms of encoded proteins. Nearly all editing events are absent or less efficient in larvae but increase at metamorphosis; the larger number and higher levels of editing suggest editing is most required when the brain is most complex. This idea is consistent with the fact that Adar mutations affect the adult brain most dramatically. However, it is unknown whether Drosophila Adar RNA editing events mediate some coherent physiological effect. To address this question, we performed a genetic screen for suppressors of Adar mutant defects. Adar5G1 null mutant flies are partially viable, severely locomotion defective, aberrantly accumulate axonal neurotransmitter pre-synaptic vesicles and associated proteins, and develop an age-dependent vacuolar brain neurodegeneration.ResultsA genetic screen revealed suppression of all Adar5G1 mutant phenotypes tested by reduced dosage of the Tor gene, which encodes a pro-growth kinase that increases translation and reduces autophagy in well-fed conditions. Suppression of Adar5G1 phenotypes by reduced Tor is due to increased autophagy; overexpression of Atg5, which increases canonical autophagy initiation, reduces aberrant accumulation of synaptic vesicle proteins and suppresses all Adar mutant phenotypes tested. Endosomal microautophagy (eMI) is another Tor-inhibited autophagy pathway involved in synaptic homeostasis in Drosophila. Increased expression of the key eMI protein Hsc70-4 also reduces aberrant accumulation of synaptic vesicle proteins and suppresses all Adar5G1 mutant phenotypes tested.ConclusionsThese findings link Drosophila Adar mutant synaptic and neurotransmission defects to more general cellular defects in autophagy; presumably, edited isoforms of CNS proteins are required for optimum synaptic response capabilities in the brain during the behaviorally complex adult life stage

Functional conservation in human and Drosophila of Metazoan ADAR2 involved in RNA editing: loss of ADAR1 in insects

Flies with mutations in the single Drosophila Adar gene encoding an RNA editing enzyme involved in editing 4% of all transcripts have severe locomotion defects and develop age-dependent neurodegeneration. Vertebrates have two ADAR-editing enzymes that are catalytically active; ADAR1 and ADAR2. We show that human ADAR2 rescues Drosophila Adar mutant phenotypes. Neither the short nuclear ADAR1p110 isoform nor the longer interferon-inducible cytoplasmic ADAR1p150 isoform rescue walking defects efficiently, nor do they correctly edit specific sites in Drosophila transcripts. Surprisingly, human ADAR1p110 does suppress age-dependent neurodegeneration in Drosophila Adar mutants whereas ADAR1p150 does not. The single Drosophila Adar gene was previously assumed to represent an evolutionary ancestor of the multiple vertebrate ADARs. The strong functional similarity of human ADAR2 and Drosophila Adar suggests rather that these are true orthologs. By a combination of direct cloning and searching new invertebrate genome sequences we show that distinct ADAR1 and ADAR2 genes were present very early in the Metazoan lineage, both occurring before the split between the Bilateria and Cnidarians. The ADAR1 gene has been lost several times, including during the evolution of insects and crustacea. These data complement our rescue results, supporting the idea that ADAR1 and ADAR2 have evolved highly conserved, distinct functions

Results of a planned interim toxicity analysis with trimodality therapy, including carboplatin AUC = 4, paclitaxel, 5-fluorouracil, amifostine, and radiation for locally advanced esophageal cancer: preliminary analyses and treatment recommendations from the North Central Cancer Treatment Group

PURPOSE: An aggressive trimodality approach from the Minnie Pearl Cancer Research Network [carboplatin AUC = 6, days 1 and 22; 5-fluorouracil 225 mg/m2 continuous infusion, days 1–42, paclitaxel 200 mg/m2, days 1 and 22; 45 Gy] has resulted in remarkable pathologic response rates but notable toxicity. This trial was designed to mitigate this toxicity by starting with a lower carboplatin dose, AUC = 4, and by adding subcutaneous amifostine. METHODS: This phase II trial included patients with locally advanced, potentially resectable esophageal cancer. All were to receive the above regimen with modifications of carboplatin AUC = 4 and amifostine 500 mg subcutaneously before radiation. All were then to undergo an esophagectomy. A planned interim toxicity analysis after the first 10 patients was to determine whether the carboplatin dose should escalate to AUC = 6. RESULTS: Ten patients were enrolled, and all required dose reductions/omissions during neoadjuvant therapy. One patient died from paclitaxel anaphylaxis. Six patients manifested a complete pathologic response. CONCLUSION: With this regimen, carboplatin AUC = 4 for patients with locally advanced esophageal cancer is appropriate

Micro-processing events in mRNAs identified by DHPLC analysis

Post-transcriptional processes such as alternative splicing and RNA editing have a huge impact on the diversity of the proteome. Detecting alternatively spliced transcripts is difficult when they are rare. In addition, edited transcripts often differ from the genomic sequence by only a few nucleotides. Denaturing high performance liquid chromatography (DHPLC) is routinely used for single nucleotide polymorphism detection and we used this method to detect alternatively spliced or edited transcripts. As the sites of RNA editing appear to be conserved within gene families, we investigated whether editing sites are conserved in the murine homologue of the Drosophila cacophony transcript encoding the α1 subunit of a voltage-gated calcium channel that is edited at 10 independent positions. Although DHPLC analysis detects RNA editing at as low as 3% in control transcripts, no evidence of RNA editing was found in the analysed murine transcript. However an alternative exon was identified at the 3′ end of the mouse Cacna1α transcript and an alternative micro-exon encoding only two amino acids (NP) was found in the extracellular loop before the IVS4 helix in the same transcript. In the homologous Drosophila transcript a micro-exon also encoding two amino acids was found at the same position before the IVS4 helix

Low-field thermal mixing in [1-13C] pyruvic acid for brute-force hyperpolarization

We detail the process of low-field thermal mixing (LFTM) between 1H and 13C nuclei in neat [1-13C] pyruvic acid at cryogenic temperatures (4–15 K). Using fast-field-cycling NMR, 1H nuclei in the molecule were polarized at modest high field (2 T) and then equilibrated with 13C nuclei by fast cycling (∼300–400 ms) to a low field (0–300 G) that activates thermal mixing. The 13C NMR spectrum was recorded after fast cycling back to 2 T. The 13C signal derives from 1H polarization via LFTM, in which the polarized (‘cold’) proton bath contacts the unpolarised (‘hot’) 13C bath at a field so low that Zeeman and dipolar interactions are similar-sized and fluctuations in the latter drive 1H–13C equilibration. By varying mixing time (tmix) and field (Bmix), we determined field-dependent rates of polarization transfer (1/τ) and decay (1/T1m) during mixing. This defines conditions for effective mixing, as utilized in ‘brute-force’ hyperpolarization of low-γ nuclei like 13C using Boltzmann polarization from nearby protons. For neat pyruvic acid, near-optimum mixing occurs for tmix ∼ 100–300 ms and Bmix ∼ 30–60 G. Three forms of frozen neat pyruvic acid were tested: two glassy samples, (one well-deoxygenated, the other O2-exposed) and one sample pre-treated by annealing (also well-deoxygenated). Both annealing and the presence of O2 are known to dramatically alter high-field longitudinal relaxation (T1) of 1H and 13C (up to 102–103-fold effects). Here, we found smaller, but still critical factors of ∼(2–5)× on both τ and T1m. Annealed, well-deoxygenated samples exhibit the longest time constants, e.g., τ ∼ 30–70 ms and T1m ∼ 1–20 s, each growing vs. Bmix. Mixing ‘turns off’ for Bmix > ∼100 G. That T1m ≫ τ is consistent with earlier success with polarization transfer from 1H to 13C by LFTM

Multi-modal imaging of high-risk ductal carcinoma in situ of the breast using C2Am: a targeted cell death imaging agent

Abstract: Background: Ductal carcinoma in situ (DCIS) is a non-invasive form of early breast cancer, with a poorly understood natural history of invasive transformation. Necrosis is a well-recognized adverse prognostic feature of DCIS, and non-invasive detection of its presence and spatial extent could provide information not obtainable by biopsy. We describe here imaging of the distribution and extent of comedo-type necrosis in a model of human DCIS using C2Am, an imaging agent that binds to the phosphatidylserine exposed by necrotic cells. Methods: We used an established xenograft model of human DCIS that mimics the histopathological features of the disease. Planar near-infrared and optoacoustic imaging, using fluorescently labeled C2Am, were used to image non-invasively the presence and extent of lesion necrosis. Results: C2Am showed specific and sensitive binding to necrotic areas in DCIS tissue, detectable both in vivo and ex vivo. The imaging signal generated in vivo using near-infrared (NIR) fluorescence imaging was up to 6-fold higher in DCIS lesions than in surrounding fat pad or skin tissue. There was a correlation between the C2Am NIR fluorescence (Pearson R = 0.783, P = 0.0125) and optoacoustic signals (R > 0.875, P < 0.022) in the DCIS lesions in vivo and the corresponding levels of cell death detected histologically. Conclusions: C2Am is a targeted multi-modal imaging agent that could complement current anatomical imaging methods for detecting DCIS. Imaging the presence and spatial extent of necrosis may give better prognostic information than that obtained by biopsy alone

Fragmentation patterns and personalized sequencing of cell-free DNA in urine and plasma of glioma patients.

Glioma-derived cell-free DNA (cfDNA) is challenging to detect using liquid biopsy because quantities in body fluids are low. We determined the glioma-derived DNA fraction in cerebrospinal fluid (CSF), plasma, and urine samples from patients using sequencing of personalized capture panels guided by analysis of matched tumor biopsies. By sequencing cfDNA across thousands of mutations, identified individually in each patient's tumor, we detected tumor-derived DNA in the majority of CSF (7/8), plasma (10/12), and urine samples (10/16), with a median tumor fraction of 6.4 × 10-3 , 3.1 × 10-5 , and 4.7 × 10-5 , respectively. We identified a shift in the size distribution of tumor-derived cfDNA fragments in these body fluids. We further analyzed cfDNA fragment sizes using whole-genome sequencing, in urine samples from 35 glioma patients, 27 individuals with non-malignant brain disorders, and 26 healthy individuals. cfDNA in urine of glioma patients was significantly more fragmented compared to urine from patients with non-malignant brain disorders (P = 1.7 × 10-2 ) and healthy individuals (P = 5.2 × 10-9 ). Machine learning models integrating fragment length could differentiate urine samples from glioma patients (AUC = 0.80-0.91) suggesting possibilities for truly non-invasive cancer detection