To evaluate and histologically qualify carbogen-induced ΔR2 as a noninvasive magnetic resonance imaging biomarker of improved tumor oxygenation using a double 2-nitroimidazole hypoxia marker ...approach.
Multigradient echo images were acquired from mice bearing GH3 prolactinomas, preadministered with the hypoxia marker CCI-103F, to quantify tumor R2 during air breathing. With the mouse remaining positioned within the magnet bore, the gas supply was switched to carbogen (95% O2, 5% CO2), during which a second hypoxia marker, pimonidazole, was administered via an intraperitoneal line, and an additional set of identical multigradient echo images acquired to quantify any changes in tumor R2. Hypoxic fraction was quantified histologically using immunofluorescence detection of CCI-103F and pimonidazole adduct formation from the same whole tumor section. Carbogen-induced changes in tumor pO2 were further validated using the Oxylite fiberoptic probe.
Carbogen challenge significantly reduced mean tumor R2 from 116 ± 13 s(-1) to 97 ± 9 s(-1) (P<.05). This was associated with a significantly lower pimonidazole adduct area (2.3 ± 1%), compared with CCI-103F (6.3 ± 2%) (P<.05). A significant correlation was observed between ΔR2 and Δhypoxic fraction (r=0.55, P<.01). Mean tumor pO2 during carbogen breathing significantly increased from 6.3 ± 2.2 mm Hg to 36.0 ± 7.5 mm Hg (P<.01).
The combined use of intrinsic susceptibility magnetic resonance imaging with a double hypoxia marker approach corroborates carbogen-induced ΔR2 as a noninvasive imaging biomarker of increased tumor oxygenation.
ABSTRACTThe aim of this study was to use the combined carbogen-ultrasmall superparamagnetic iron oxide (CUSPIO) magnetic resonance imaging (MRI) method, which uses spatial correlations in independent ...susceptibility imaging biomarkers, to investigate and compare the impact of tumor size and anatomical site on vascular structure and function in vivo. Mice bearing either subcutaneous or orthotopic PC3 LN3 prostate tumors were imaged at 7 T, using a multi-gradient echo sequence to quantify R2, before and during carbogen (95% O2/5% CO2) breathing, and subsequently following intravenous administration of USPIO particles. Carbogen and USPIO-induced changes in R2 were used to inform on hemodynamic vasculature and fractional blood volume (%), respectively. The CUSPIO imaging data were also segmented to identify and assess five categories of R2 response. Small and large subcutaneous and orthotopic tumor cohorts all exhibited significantly (P < 0.05) different median baseline R2, ΔR2carbogen, and fractional blood volume. CUSPIO imaging showed that small subcutaneous tumors predominantly exhibited a negative ΔR2carbogen followed by a positive ΔR2USPIO, consistent with a well perfused tumor vasculature. Large subcutaneous tumors exhibited a small positive ΔR2carbogen and relatively low fractional blood volume, suggesting less functional vasculature. Orthotopic tumors revealed a large, positive ΔR2carbogen, consistent with vascular steal, and which may indicate that vascular function is more dependent on site of implantation than tumor size. Regions exhibiting significant ΔR2carbogen, but no significant ΔR2USPIO, suggesting transient vascular shutdown over the experimental timecourse, were apparent in all 3 cohorts. CUSPIO imaging can inform on efficient drug delivery via functional vasculature in vivo, and on appropriate tumor model selection for pre-clinical therapy trials
A survey of a population-based sample of U.S adults was conducted to measure their attitudes about, and inform the design of the Precision Medicine Initiative's planned national cohort study.
An ...online survey was conducted by GfK between May and June of 2015. The influence of different consent models on willingness to share data was examined by randomizing participants to one of eight consent scenarios.
Of 4,777 people invited to take the survey, 2,706 responded and 2,601 (54% response rate) provided valid responses. Most respondents (79%) supported the proposed study, and 54% said they would definitely or probably participate if asked. Support for and willingness to participate in the study varied little among demographic groups; younger respondents, LGBT respondents, and those with more years of education were significantly more likely to take part if asked. The most important study incentive that the survey asked about was learning about one's own health information. Willingness to share data and samples under broad, study-by-study, menu and dynamic consent models was similar when a statement about transparency was included in the consent scenarios. Respondents were generally interested in taking part in several governance functions of the cohort study.
A large majority of the U.S. adults who responded to the survey supported a large national cohort study. Levels of support for the study and willingness to participate were both consistent across most demographic groups. The opportunity to learn health information about one's self from the study appears to be a strong motivation to participate.
Abstract
Overexpression of EGFR has been identified as a negative prognostic factor in squamous cell carcinoma of the head and neck (SCCHN). Patients with SCCHN who respond to EGFR-targeted tyrosine ...kinase inhibitors (TKIs) eventually develop acquired resistance. Colocalization of EGFR expression and tumor hypoxia in SCCHN is associated with poor outcome, suggesting a role for hypoxia in drug resistance. Non-invasive imaging strategies to accurately identify and monitor patients whose tumors have become resistant to EGFR-TKI therapy would have clinical value. As part of a pre-clinical multiparametric imaging study, we have investigated EGFR-TKI resistance using intrinsic susceptibility magnetic resonance imaging (IS-MRI), which relies on the dependence of the MRI transverse relaxation rate R2* on the ratio of oxy- to deoxyhemoglobin in blood. Given its relationship to blood oxygen saturation and pO2 in and around blood vessels, R2* and hyperoxia-induced ΔR2* are being investigated as imaging biomarkers of tumor oxygenation.
IS-MRI was performed on size-matched xenografts derived from the EGFR TKI sensitive SCCHN cell line CAL27 and an isogenic subline resistant to multiple TKIs (gefitinib, erlotinib, and afatinib). Tumor-bearing mice were administered the hypoxia marker pimonidazole, and baseline R2* quantified from resistant (n=8) or sensitive (n=7) tumors whilst the host breathed air. Gas delivery was then switched to 100% O2, and tumour R2* measured again. Finally, mice were administered the perfusion marker Hoechst 33342. The extent of functional tumor vasculature and hypoxia were quantified ex vivo using fluorescence microscopy. Resistant tumors revealed regions of fast R2* (functional, deoxygenated vasculature) restricted primarily to the tumor periphery, while sensitive tumors exhibited a more heterogeneous distribution of fast R2* throughout. There was no significant difference in baseline R2* between the two cohorts (64 ± 4s-1 and 76 ± 5s-1, p=0.07). Hyperoxia resulted in a significantly smaller ΔR2* in the resistant tumors (-2.4 ± 1.4s-1) compared to sensitive tumors (-9.1 ± 2s-1, p<0.05). Resistant tumors had significantly lower Hoechst 33342 uptake (9.5 ± 1.3%, p<0.01) and increased pimonidazole adducts (21 ± 2%, p<0.01) compared to sensitive tumors (19.2 ± 3% and 10.4 ± 2% respectively). Tumor regions of fast R2* and hyperoxic-induced ΔR2* were spatially associated with Hoechst 33342 uptake.
Tumors with resistance to EGFR-TKIs exhibited a reduced hemodynamic MRI response that was associated with decreased vessel perfusion and increased tumor hypoxia. IS-MRI informs on phenotypic differences in tumor blood vessel distribution, functionality and oxygenation associated with EGFR-TKI resistance and sensitivity, affording useful non-invasive imaging biomarkers for investigating EGFR drug resistance and tumor hypoxia.
Citation Format: Lauren CJ Baker, Carol Box, Arti Sikka, Gary Box, Suzanne A. Eccles, Simon P. Robinson. Evaluating imaging biomarkers of acquired resistance to targeted EGFR therapy in xenograft models of human squamous cell carcinoma of the head and neck (SCCHN). abstract. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 4459. doi:10.1158/1538-7445.AM2013-4459
Respiratory syncytial virus (RSV) is a worldwide public health concern for which no vaccine is available. Elucidation of the prefusion structure of the RSV F glycoprotein and its identification as ...the main target of neutralizing antibodies have provided new opportunities for development of an effective vaccine. Here, we describe the structure-based design of a self-assembling protein nanoparticle presenting a prefusion-stabilized variant of the F glycoprotein trimer (DS-Cav1) in a repetitive array on the nanoparticle exterior. The two-component nature of the nanoparticle scaffold enabled the production of highly ordered, monodisperse immunogens that display DS-Cav1 at controllable density. In mice and nonhuman primates, the full-valency nanoparticle immunogen displaying 20 DS-Cav1 trimers induced neutralizing antibody responses ∼10-fold higher than trimeric DS-Cav1. These results motivate continued development of this promising nanoparticle RSV vaccine candidate and establish computationally designed two-component nanoparticles as a robust and customizable platform for structure-based vaccine design.
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•Design of a self-assembling protein immunogen displaying 20 copies of prefusion RSV F•In vitro assembly yields highly ordered immunogens with tunable antigen density•The nanoparticle immunogens induce potent neutralizing antibody responses•Fusion of DS-Cav1 to the trimeric nanoparticle subunit stabilizes the antigen
A computationally designed self-assembling nanoparticle that displays 20 copies of a trimeric viral protein induces potent neutralizing antibody responses.
The regular arrangements of β-strands around a central axis in β-barrels and of α-helices in coiled coils contrast with the irregular tertiary structures of most globular proteins, and have ...fascinated structural biologists since they were first discovered. Simple parametric models have been used to design a wide range of α-helical coiled-coil structures, but to date there has been no success with β-barrels. Here we show that accurate de novo design of β-barrels requires considerable symmetry-breaking to achieve continuous hydrogen-bond connectivity and eliminate backbone strain. We then build ensembles of β-barrel backbone models with cavity shapes that match the fluorogenic compound DFHBI, and use a hierarchical grid-based search method to simultaneously optimize the rigid-body placement of DFHBI in these cavities and the identities of the surrounding amino acids to achieve high shape and chemical complementarity. The designs have high structural accuracy and bind and fluorescently activate DFHBI in vitro and in Escherichia coli, yeast and mammalian cells. This de novo design of small-molecule binding activity, using backbones custom-built to bind the ligand, should enable the design of increasingly sophisticated ligand-binding proteins, sensors and catalysts that are not limited by the backbone geometries available in known protein structures.
The global supply of COVID-19 vaccines remains limited. An understanding of the immune response that is predictive of protection could facilitate rapid licensure of new vaccines. Data from a ...randomized efficacy trial of the ChAdOx1 nCoV-19 (AZD1222) vaccine in the United Kingdom was analyzed to determine the antibody levels associated with protection against SARS-CoV-2. Binding and neutralizing antibodies at 28 days after the second dose were measured in infected and noninfected vaccine recipients. Higher levels of all immune markers were correlated with a reduced risk of symptomatic infection. A vaccine efficacy of 80% against symptomatic infection with majority Alpha (B.1.1.7) variant of SARS-CoV-2 was achieved with 264 (95% CI: 108, 806) binding antibody units (BAU)/ml: and 506 (95% CI: 135, not computed (beyond data range) (NC)) BAU/ml for anti-spike and anti-RBD antibodies, and 26 (95% CI: NC, NC) international unit (IU)/ml and 247 (95% CI: 101, NC) normalized neutralization titers (NF
) for pseudovirus and live-virus neutralization, respectively. Immune markers were not correlated with asymptomatic infections at the 5% significance level. These data can be used to bridge to new populations using validated assays, and allow extrapolation of efficacy estimates to new COVID-19 vaccines.
Shigella sonnei causes shigellosis, a severe gastrointestinal illness that is sexually transmissible among men who have sex with men (MSM). Multidrug resistance in S. sonnei is common including ...against World Health Organisation recommended treatment options, azithromycin, and ciprofloxacin. Recently, an MSM-associated outbreak of extended-spectrum β-lactamase producing, extensively drug resistant S. sonnei was reported in the United Kingdom. Here, we aimed to identify the genetic basis, evolutionary history, and international dissemination of the outbreak strain. Our genomic epidemiological analyses of 3,304 isolates from the United Kingdom, Australia, Belgium, France, and the United States of America revealed an internationally connected outbreak with a most recent common ancestor in 2018 carrying a low-fitness cost resistance plasmid, previously observed in travel associated sublineages of S. flexneri. Our results highlight the persistent threat of horizontally transmitted antimicrobial resistance and the value of continuing to work towards early and open international sharing of genomic surveillance data.
Introduction
Although the distinction between passive and active suicidal ideation is well accepted by suicide researchers and clinicians, there has been very little empirical investigation into this ...distinction. The current study addressed this gap by examining the latent structure of suicidal ideation based on thought content.
Method
Participants from two distinct samples of U.S. adults (n1 = 6200; n2 = 10,625) completed a self‐report assessment of eight commonly experienced suicidal thoughts using the Self‐Injurious Thoughts and Behaviors Interview‐Revised. Exploratory structural equation modeling was used to examine the latent structure of suicidal thoughts.
Results
The two‐factor model demonstrated significantly better fit than the one‐factor solution across both samples. Thoughts typically classified as passive ideation strongly loaded onto one factor, whereas thoughts typically classified as active ideation loaded onto the second factor. The two factors were highly correlated and some suicidal thoughts exhibited meaningful cross‐loading.
Conclusion
Our results suggest that passive and active ideation are two distinct constructs. Although they often co‐occur, passive and active ideation are not nested constructs and should not be viewed as gradients of one underlying construct. Our findings suggest that at a minimum both passive and active ideation should be included in all suicide risk assessments and screenings.
A documented consequence of poxvirus infections is global inhibition of host protein synthesis and reduction in mRNA levels. We examined this mRNA decrease by infecting A549 cells, derived from a ...human lung carcinoma, with rabbitpox virus (RPV), or RPV deleted for the serine protease inhibitor SPI-1 (RPVΔSPI-1), which exhibits a growth defect on A549 cells. At various times postinfection, mRNA profiles were analyzed using Affymetrix U95AV2 microarrays. There was a decline in overall cellular mRNA levels beginning at 2.5 hpi, and by 5 hpi, mRNA levels were drastically reduced for the majority of genes. However, several mRNAs increased, including those of heat-shock genes. Finally, a comparison of host mRNA profiles of RPV- to RPVΔSPI-1-infected cells revealed subtle differences in mRNA levels at 5 and 12 hpi. In summary, while there was a global decrease of host mRNA levels, the induction of selected mRNAs may be required for a successful poxvirus infection.
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