A Biodistribution and Toxicity Study of Cobalt Dichloride–NAcetyl Cysteine (C4) as an Implantable MRI Marker for Prostate Cancer Treatment

Purpose—C4, a cobalt dichloride–N-acetyl cysteine complex, is being developed as a positivesignal magnetic resonance imaging (MRI) marker to localize implanted radioactive seeds in prostate brachytherapy. We evaluated the toxicity and biodistribution of C4 in rats with the goal of simulating systemic effects of potential leakage from C4 MRI markers within the prostate. Methods—9 μl doses (equivalent to leakage from 120 markers in a human) of control (0.9% sodium chloride), 1% (proposed for clinical use) and 10% C4 solution were injected into the prostates of male Sprague-Dawley rats via laparotomy. Organ toxicity and cobalt disposition in plasma, tissues, feces and urine were evaluated. Results—No C4-related morbidity or mortality was observed in the biodistribution arm (60 rats). Biodistribution was measurable following 10% C4 injection: cobalt was cleared rapidly from periprostatic tissue; mean concentrations in prostate were 163 μg/g and 268 μg/g at 5 and 30 minutes but were undetectable by 60 minutes. Expected dual renal-hepatic elimination was observed with % injected dose recovered in tissues of 39.0 ±5.6% (liver) \u3e 11.8 ±6.5% (prostate) \u3e 5.3 ±0.9% (kidney) with low plasma concentrations detected up to 1 hr (1.40 μg/ml at 5–60 minutes). Excretion in urine was 13.1 ±4.6 % with 3.1 ±0.54 % recovered in feces by 24 hours. In the toxicity arm, three animals died in the control group and 1 each in the 1% and 10% groups from surgical or anesthesia-related complications; all others survived to scheduled termination at 14 days. No C4-related adverse clinical signs or organ toxicity was observed. Conclusion—C4-related toxicity was not observed at exposures at least 10-fold that proposed for human use. This data demonstrating lack of systemic toxicity with dual routes of elimination in the event of in-situ rupture suggests C4 warrants further investigation as an MRI marker for prostate brachytherapy

Comparative Functional Genomics Analysis of NNK Tobacco-Carcinogen Induced Lung Adenocarcinoma Development in Gprc5a-Knockout Mice

Background: Improved understanding of lung cancer development and progression, including insights from studies of animal models, are needed to combat this fatal disease. Previously, we found that mice with a knockout (KO) of G-protein coupled receptor 5A (Gprc5a) develop lung tumors after a long latent period (12 to 24 months). Methodology/Principal Findings: To determine whether a tobacco carcinogen will enhance tumorigenesis in this model, we administered 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) i.p. to 2-months old Gprc5a-KO mice and sacrificed groups (n = 5) of mice at 6, 9, 12, and 18 months later. Compared to control Gprc5a-KO mice, NNK-treated mice developed lung tumors at least 6 months earlier, exhibited 2- to 4-fold increased tumor incidence and multiplicity, and showed a dramatic increase in lesion size. A gene expression signature, NNK-ADC, of differentially expressed genes derived by transcriptome analysis of epithelial cell lines from normal lungs of Gprc5a-KO mice and from NNK-induced adenocarcinoma was highly similar to differential expression patterns observed between normal and tumorigenic human lung cells. The NNK-ADC expression signature also separated both mouse and human adenocarcinomas from adjacent normal lung tissues based on publicly available microarray datasets. A key feature of the signature, up-regulation of Ube2c, Mcm2, and Fen1, was validated in mouse normal lung and adenocarcinoma tissues and cells by immunohistochemistry and western blotting, respectively

Impact of COVID-19 on cardiovascular testing in the United States versus the rest of the world

Objectives: This study sought to quantify and compare the decline in volumes of cardiovascular procedures between the United States and non-US institutions during the early phase of the coronavirus disease-2019 (COVID-19) pandemic. Background: The COVID-19 pandemic has disrupted the care of many non-COVID-19 illnesses. Reductions in diagnostic cardiovascular testing around the world have led to concerns over the implications of reduced testing for cardiovascular disease (CVD) morbidity and mortality. Methods: Data were submitted to the INCAPS-COVID (International Atomic Energy Agency Non-Invasive Cardiology Protocols Study of COVID-19), a multinational registry comprising 909 institutions in 108 countries (including 155 facilities in 40 U.S. states), assessing the impact of the COVID-19 pandemic on volumes of diagnostic cardiovascular procedures. Data were obtained for April 2020 and compared with volumes of baseline procedures from March 2019. We compared laboratory characteristics, practices, and procedure volumes between U.S. and non-U.S. facilities and between U.S. geographic regions and identified factors associated with volume reduction in the United States. Results: Reductions in the volumes of procedures in the United States were similar to those in non-U.S. facilities (68% vs. 63%, respectively; p = 0.237), although U.S. facilities reported greater reductions in invasive coronary angiography (69% vs. 53%, respectively; p < 0.001). Significantly more U.S. facilities reported increased use of telehealth and patient screening measures than non-U.S. facilities, such as temperature checks, symptom screenings, and COVID-19 testing. Reductions in volumes of procedures differed between U.S. regions, with larger declines observed in the Northeast (76%) and Midwest (74%) than in the South (62%) and West (44%). Prevalence of COVID-19, staff redeployments, outpatient centers, and urban centers were associated with greater reductions in volume in U.S. facilities in a multivariable analysis. Conclusions: We observed marked reductions in U.S. cardiovascular testing in the early phase of the pandemic and significant variability between U.S. regions. The association between reductions of volumes and COVID-19 prevalence in the United States highlighted the need for proactive efforts to maintain access to cardiovascular testing in areas most affected by outbreaks of COVID-19 infection

Haploinsufficiency of Mdm2 and Mdm4 in Tumorigenesis and Development▿

The tumor suppressor p53 is inactivated by multiple mechanisms that include mutations of the p53 gene itself and increased levels of the p53 inhibitors MDM2 and MDM4. Mice lacking Mdm2 or Mdm4 exhibit embryo-lethal phenotypes that are completely rescued by concomitant deletion of p53. Here we show that Mdm2 and Mdm4 haploinsufficiency leads to increased p53 activity, exhibited as increased sensitivity to DNA damage and decreased transformation potential. Moreover, in in vivo tumor development, Eμ-myc Mdm4+/− mice show a delayed onset of B-cell lymphomas compared to Eμ-myc mice. Additionally, Mdm2+/− Mdm4+/− double-heterozygous mice are not viable and exhibit defects in hematopoiesis and cerebellar development. The defects in Mdm2+/− Mdm4+/− mice are corrected by deletion of a single p53 allele. These findings highlight the exquisite sensitivity of p53 to Mdm2 and Mdm4 levels and suggest that some cell types may be more sensitive to therapeutic drugs that inhibit the Mdm-p53 interaction

The Antimelanoma Immunocytokine scFvMEL/TNF Shows Reduced Toxicity and Potent Antitumor Activity against Human Tumor Xe nog rafts1

The immunocytokine scFvMEL/TNF, a fusion protein composed of human tumor necrosis factor (TNF) and a single-chain Fv antibody (scFv) scFvMEL targeting the melanoma gp240 antigen, demonstrates impressive cytotoxic effects against human melanoma cell lines in vitro. Pharmacokinetic studies of (125)I-scFvMEL/TNF in BALB/c mice showed that the construct clears from the circulation with a terminal-phase half-life of 17.6 hours after intravenous administration. The maximum tolerated dose of scFvMEL/TNF in nude mice was 4 mg/kg, i.v., on a daily x5 schedule. There were no changes in gross pathology, clinical chemistry, or hematologic parameters in mice treated at doses of up to 3 mg/kg. Therapeutic studies at a dose of 2.5 mg/kg on athymic mice bearing established (∼ 50 mm(3)) human melanoma A375GFP xenograft tumors transfected with green fluorescent protein demonstrated potent tumor suppression and complete tumor regression of all lesions. There was no subsequent outgrowth of tumors from mice rendered tumor-free. These data show that scFvMEL/TNF can target melanoma cells in vivo and can result in pronounced antimelanoma effects after systemic administration. Toxicology studies indicate the relative safety of this agent at doses that are therapeutically effective and provide guidance to projected phase I starting doses on patients at this schedule