Combination therapy in a xenograft model of glioblastoma: enhancement of the antitumor activity of temozolomide by an MDM2 antagonist

OBJECTIVE Improvement in treatment outcome for patients with glioblastoma multiforme (GBM) requires a multifaceted approach due to dysregulation of numerous signaling pathways. The murine double minute 2 (MDM2) protein may fulfill this requirement because it is involved in the regulation of growth, survival, and invasion. The objective of this study was to investigate the impact of modulating MDM2 function in combination with front-line temozolomide (TMZ) therapy in GBM. METHODS The combination of TMZ with the MDM2 protein-protein interaction inhibitor nutlin3a was evaluated for effects on cell growth, p53 pathway activation, expression of DNA repair proteins, and invasive properties. In vivo efficacy was assessed in xenograft models of human GBM. RESULTS In combination, TMZ/nutlin3a was additive to synergistic in decreasing growth of wild-type p53 GBM cells. Pharmacodynamic studies demonstrated that inhibition of cell growth following exposure to TMZ/nutlin3a correlated with: 1) activation of the p53 pathway, 2) downregulation of DNA repair proteins, 3) persistence of DNA damage, and 4) decreased invasion. Pharmacokinetic studies indicated that nutlin3a was detected in human intracranial tumor xenografts. To assess therapeutic potential, efficacy studies were conducted in a xenograft model of intracranial GBM by using GBM cells derived from a recurrent wild-type p53 GBM that is highly TMZ resistant (GBM10). Three 5-day cycles of TMZ/nutlin3a resulted in a significant increase in the survival of mice with GBM10 intracranial tumors compared with single-agent therapy. CONCLUSIONS Modulation of MDM2/p53-associated signaling pathways is a novel approach for decreasing TMZ resistance in GBM. To the authors' knowledge, this is the first study in a humanized intracranial patient-derived xenograft model to demonstrate the efficacy of combining front-line TMZ therapy and an inhibitor of MDM2 protein-protein interactions

Development of a new method to measure hydrogen sulfide using the vitamin B12 precursor cobinamide

Hydrogen sulfide is a deadly gas for which no point-of- care device for measuring biological samples exists. Current methods of measuring sulfide include high performance liquid chromatography and gas chromatography/ mass spectrometry, but these methods require non-portable equipment. Another technique for measuring sulfide is Ellman's test; although it has a high level of sensitivity and can be measured in a spectrophotometer, it has a low dynamic range, as precipitates can form at high concentrations. The results presented here use the vitamin B12 precursor, cobinamide, which goes through a spectral shift upon binding of sulfide, to measure sulfide levels. Here it is shown that cobinamide binds to sulfide with a binding affinity of 5.27 x 10⁸ M⁻¹. The limit of detection and limit of quantification of this assay are calculated to be 1.88 [mu]M and 7.21 [mu]M, respectively. Although the cobinamide assay is not as sensitive as Ellman's test, the cobinamide assay is simpler and these limits are still sufficient since sulfide poisoning victims have blood concentrations of sulfide in the micromolar range. To simulate biological samples, Conway diffusion cells have been used. In these cells, the smallest percentage of recovery of hydrogen sulfide is 95.9%, which suggests that measurement in biological samples is possibl

Sulfanegen sodium treatment in a rabbit model of sub-lethal cyanide toxicity.

The aim of this study is to investigate the ability of intramuscular and intravenous sulfanegen sodium treatment to reverse cyanide effects in a rabbit model as a potential treatment for mass casualty resulting from cyanide exposure. Cyanide poisoning is a serious chemical threat from accidental or intentional exposures. Current cyanide exposure treatments, including direct binding agents, methemoglobin donors, and sulfur donors, have several limitations. Non-rhodanese mediated sulfur transferase pathways, including 3-mercaptopyruvate sulfurtransferase (3-MPST) catalyze the transfer of sulfur from 3-MP to cyanide, forming pyruvate and less toxic thiocyanate. We developed a water-soluble 3-MP prodrug, 3-mercaptopyruvatedithiane (sulfanegen sodium), with the potential to provide a continuous supply of substrate for CN detoxification. In addition to developing a mass casualty cyanide reversal agent, methods are needed to rapidly and reliably diagnose and monitor cyanide poisoning and reversal. We use non-invasive technology, diffuse optical spectroscopy (DOS) and continuous wave near infrared spectroscopy (CWNIRS) to monitor physiologic changes associated with cyanide exposure and reversal. A total of 35 animals were studied. Sulfanegen sodium was shown to reverse the effects of cyanide exposure on oxyhemoglobin and deoxyhemoglobin rapidly, significantly faster than control animals when administered by intravenous or intramuscular routes. RBC cyanide levels also returned to normal faster following both intramuscular and intravenous sulfanegen sodium treatment than controls. These studies demonstrate the clinical potential for the novel approach of supplying substrate for non-rhodanese mediated sulfur transferase pathways for cyanide detoxification. DOS and CWNIRS demonstrated their usefulness in optimizing the dose of sulfanegen sodium treatment

Comparison of Insulin Infusion Protocols Targeting 110-140 mg/dL in Patients After Cardiac Surgery.

BACKGROUND: Continuous intravenous insulin infusion (CII) following coronary artery bypass graft (CABG) surgery reduces postoperative complications and hospitalization duration. Because of limited data evaluating outcomes of CII with revised glycemic targets (110-140 mg/dL) in cardiac surgery, this study compared efficacy and safety of two different CII protocols having revised targets. SUBJECTS AND METHODS: This is a retrospective study comparing two different protocols between August 2009 and March 2010. Protocol 1 consists of four algorithms, and Protocol 2 is a table to adjust CII. Blood glucose (BG) and CII rates were recorded for 48 h postoperatively or CII discontinuation. Efficacy was defined by the percentage of BG values in the target range, and safety was defined by the percentage of BG values/dL. RESULTS: Protocol 1 (n=117) patients were older (65 vs. 61 years; P=0.006) and had more CABG and fewer valve procedures compared with Protocol 2 (n=130). There were no differences in baseline BG level (149±40.6 vs. 151±38.1 mg/dL), body mass index (30±6.3 vs. 30±6.4 kg/m(2)), hematocrit (28% vs. 28%), percentage of diabetes patients (32% vs. 31%), percentage of patients with glomerular filtration rate of/min (5% vs. 6%), CII duration (42 [9-48] vs. 40 [14-48] h), total insulin units received (99 [15-376] vs. 114 [12-457]), hourly insulin rate (median of average rate [range], 2.59 [0-21) vs. 2.96 [0-25] units/h), percentage of BG values 110-140 mg/dL,/dL, 40-69 mg/dL, and \u3e180 mg/dL, and BG coefficient of variation (21±6.5 vs. 21±6.1). Shorter time to goal (3.32 [0.22-19.35] vs. 5.03 [0.92-19.80] h; P=0.018) and lower mean BG level (127±12.2 vs. 133±12.1 mg/dL; P DISCUSSION: CII protocols targeting 110-140 mg/dL were effective in achieving revised targets with low hypoglycemia. Despite differences in mean BG level and time to target, each hospital continued using its existing protocols and identified areas for improvement

Immunomodulatory drugs have divergent effects on humoral and cellular immune responses to SARS-CoV-2 vaccination in people living with rheumatoid arthritis

Abstract Understanding the efficacy of SARS-CoV-2 vaccination in people on immunosuppressive drugs, including those with rheumatoid arthritis (RA), is critical for their protection. Vaccine induced protection requires antibodies, CD4+ T cells, and CD8+ T cells, but it is unclear if these are equally affected by immunomodulatory drugs. Here, we determined how humoral and cellular SARS-CoV-2 vaccination responses differed between people with RA and controls, and which drug classes impacted these responses. Blood was collected from participants with RA on immunomodulatory drugs and controls after their second, third, and fourth SARS-CoV-2 vaccinations. Receptor binding domain (RBD)-specific antibodies were quantified by ELISA. Spike-specific memory T cells were quantitated using flow cytometry. Linear mixed models assessed the impact of age, sex, and immunomodulatory drug classes on SARS-CoV-2 vaccination responses. Compared to non-RA controls (n = 35), participants with RA on immunomodulatory drugs (n = 62) had lower anti-RBD IgG and spike-specific CD4+ T cell levels, but no deficits in spike-specific CD8+ T cells, following SARS-CoV-2 vaccination. Use of costimulation inhibitors was associated with lower humoral responses. JAK inhibitors were associated with fewer spike-specific CD4+ T cells. Participants with RA on immunomodulatory drugs mounted weaker responses to SARS-CoV-2 vaccination, with different drug classes impacting the cellular and humoral compartments

Analysis of Outcomes in Ischemic vs Nonischemic Cardiomyopathy in Patients With Atrial Fibrillation A Report From the GARFIELD-AF Registry

IMPORTANCE Congestive heart failure (CHF) is commonly associated with nonvalvular atrial fibrillation (AF), and their combination may affect treatment strategies and outcomes