α,α9-Bis-(dimethylammonium-acetaldehyde diethylacetal)- p,p9 -diacetylbiphenyl bromide (DMAE) has been found to potentiate responses to sympathetic nerve stimulation and catecholamine administration. Potentiation of the contraction of the cat nictitating membrane after cervical sympathetic nerve stimulation was more pronounced at low than at high frequency. The height and duration of the contractions of the nictitating membrane in response to epinephrine or norepinephrine and the pre- or postganglionic stimulations of the cervical sympathetic nerve were increased markedly after DMAE. The blood pressure in cats and dogs was increased after administration of DMAE. In reserpine-pretreated dogs and approximately 10% of the nonreserpine-pretreated dogs, a depressor response to DMAE was observed. Blood pressure responses to epinephrine and norepinephrine in the normal and reserpine-pretreated cats and dogs were increased significantly after DMAE. Cocaine and DMAE appeared to demonstrate parallel ability to enhance sympathomimetic effects of various phenylethylamine derivatives with direct actions. DMAE and cocaine did not potentiate responses to sympathomimetic amines with indirect actions. Tyramine responses in the isolated guinea-pig atria were antagonized by DMAE. Similarities and differences between DMAE and cocaine are discussed. DMAE is a close structural analog of hemicholinium but demonstrates marked differences in pharmacologic properties.
Abstract Background DNA methylation at a gene promoter region has the potential to regulate gene transcription. Patterns of methylation over multiple CpG sites in a region are often complex and cell type specific, with the region showing multiple allelic patterns in a sample. This complexity is commonly obscured when DNA methylation data is summarised as an average percentage value for each CpG site (or aggregated across CpG sites). True representation of methylation patterns can only be fully characterised by clonal analysis. Deep sequencing provides the ability to investigate clonal DNA methylation patterns in unprecedented detail and scale, enabling the proper characterisation of the heterogeneity of methylation patterns. However, the sheer amount and complexity of sequencing data requires new synoptic approaches to visualise the distribution of allelic patterns. Results We have developed a new analysis and visualisation software tool “Methpat”, that extracts and displays clonal DNA methylation patterns from massively parallel sequencing data aligned using Bismark. Methpat was used to analyse multiplex bisulfite amplicon sequencing on a range of CpG island targets across a panel of human cell lines and primary tissues. Methpat was able to represent the clonal diversity of epialleles analysed at specific gene promoter regions. We also used Methpat to describe epiallelic DNA methylation within the mitochondrial genome. Conclusions Methpat can summarise and visualise epiallelic DNA methylation results from targeted amplicon, massively parallel sequencing of bisulfite converted DNA in a compact and interpretable format. Unlike currently available tools, Methpat can visualise the diversity of epiallelic DNA methylation patterns in a sample.
Loss of MHC class I (MHC-I) antigen presentation in cancer cells can elicit immunotherapy resistance. A genome-wide CRISPR/Cas9 screen identified an evolutionarily conserved function of polycomb repressive complex 2 (PRC2) that mediates coordinated transcriptional silencing of the MHC-I antigen processing pathway (MHC-I APP), promoting evasion of T cell-mediated immunity. MHC-I APP gene promoters in MHC-I low cancers harbor bivalent activating H3K4me3 and repressive H3K27me3 histone modifications, silencing basal MHC-I expression and restricting cytokine-induced upregulation. Bivalent chromatin at MHC-I APP genes is a normal developmental process active in embryonic stem cells and maintained during neural progenitor differentiation. This physiological MHC-I silencing highlights a conserved mechanism by which cancers arising from these primitive tissues exploit PRC2 activity to enable immune evasion.
<div>AbstractPurpose:<p>Brain involvement occurs in the majority of patients with metastatic melanoma. The potential of circulating tumor DNA (ctDNA) for surveillance and monitoring systemic therapy response in patients with melanoma brain metastases merits investigation.</p>Experimental Design:<p>This study examined circulating <i>BRAF, NRAS</i>, and <i>c-KIT</i> mutations in patients with melanoma with active brain metastases receiving PD-1 inhibitor–based therapy. Intracranial and extracranial disease volumes were measured using the sum of product of diameters, and response assessment performed using RECIST. Longitudinal plasma samples were analyzed for ctDNA over the first 12 weeks of treatment (threshold 2.5 copies/mL plasma).</p>Results:<p>Of a total of 72 patients, 13 patients had intracranial metastases only and 59 patients had concurrent intracranial and extracranial metastases. ctDNA detectability was 0% and 64%, respectively, and detectability was associated with extracranial disease volume (<i>P</i> < 0.01). Undetectable ctDNA on-therapy was associated with extracranial response (<i>P</i> < 0.01) but not intracranial response. The median overall survival in patients with undetectable (<i>n</i> = 34) versus detectable (<i>n</i> = 38) ctDNA at baseline was 39.2 versus 10.6 months [HR, 0.51; 95% confidence interval (CI), 0.28–0.94; <i>P</i> = 0.03] and on-therapy was 39.2 versus 9.2 months (HR, 0.32; 95% CI, 0.16–0.63; <i>P</i> < 0.01).</p>Conclusions:<p>ctDNA remains a strong prognostic biomarker in patients with melanoma with brain metastases, especially in patients with concurrent extracranial disease. However, ctDNA was not able to detect or monitor intracranial disease activity, and we recommend against using ctDNA as a sole test during surveillance and therapeutic monitoring in patients with melanoma.</p></div>
<div>AbstractPurpose:<p>We evaluated the predictive value of pretreatment ctDNA to inform therapeutic outcomes in patients with metastatic melanoma relative to type and line of treatment.</p>Experimental Design:<p>Plasma circulating tumor DNA (ctDNA) was quantified in 125 samples collected from 110 patients prior to commencing treatment with immune checkpoint inhibitors (ICIs), as first- (<i>n</i> = 32) or second-line (<i>n</i> = 27) regimens, or prior to commencing first-line BRAF/MEK inhibitor therapy (<i>n</i> = 66). An external validation cohort included 128 patients commencing ICI therapies in the first- (<i>N</i> = 77) or second-line (<i>N</i> = 51) settings.</p>Results:<p>In the discovery cohort, low ctDNA (≤20 copies/mL) prior to commencing therapy predicted longer progression-free survival (PFS) in patients treated with first-line ICIs [HR, 0.20; 95% confidence interval (CI) 0.07–0.53; <i>P</i> < 0.0001], but not in the second-line setting. An independent cohort validated that ctDNA is predictive of PFS in the first-line setting (HR, 0.42; 95% CI, 0.22–0.83; <i>P</i> = 0.006), but not in the second-line ICI setting. Moreover, ctDNA prior to commencing ICI treatment was not predictive of PFS for patients pretreated with BRAF/MEK inhibitors in either the discovery or validation cohorts. Reduced PFS and overall survival were observed in patients with high ctDNA receiving anti–PD-1 monotherapy, relative to those treated with combination anti–CTLA-4/anti–PD-1 inhibitors.</p>Conclusions:<p>Pretreatment ctDNA is a reliable indicator of patient outcome in the first-line ICI treatment setting, but not in the second-line ICI setting, especially in patients pretreated with BRAF/MEK inhibitors. Preliminary evidence indicated that treatment-naïve patients with high ctDNA may preferentially benefit from combined ICIs.</p></div>
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