Inhibition of mast cell histamine release by flavonoids and biflavonoids

The effect of 11 flavonoids and 4 biflavonoids on the release of histamine from peritoneal rat mast cells induced by compound 48/80 and calcium ionophore A23187 was studied. Dihydroflavonoids (flavanones) and (+)-catechin did not modify histamine release induced by both secretagogues. Flavone, apigenin and cromoglycate inhibited the secretion elicited by compound 48/80 but did not modify the A23187-induced secretion. The effect of kaempferol on the compound 48/80-induced histamine release was biphasic. Low doses (10 (-6) to 10 (-5)M) of the compound potentiated secretion whereas higher doses inhibited histamine secretion. Some of the drugs tested revealed a higher potency as referred to quercetin. Luteolin, a tetrahydroxyflavone and amentoflavone, a biapigenin, exhibited the highest inhibitory effects of mast cell histamine secretion.     

Evaluation and improvement of homovanillic acid methodology, and a critique of liquid chromatography with electrochemical detection

Resolution of several problems encountered with some organic solvent extraction-fluorometric procedures commonly used to measure homovanillic acid (HVA) in urine resulted in a more specific and sensitive methodology, applicable to diverse biological material. Purification on an anion-exchange resin followed by extraction with organic solvent was the most reliable and specific for HVA. Eluting the resin with a near-boiling solution of NaCl concentrated the HVA in a smaller volume with no increase in the blank reading. In none of the other methods was enough oxidizing agent used to completely oxidize the excessive amounts of HVA in urines of patients with neuroblastoma. 5-Hydroxyindoleacetic acid interferes with the HVA fluorophor. Several of the advantages and problems with "high-pressure" liquid chromatography with electrochemical detection are identified, particularly the unpredictable nature of the working electrode.     

Interaction of the synthetic ultimate carcinogens, N-sulfonoxy- and N-acetoxy-2-acetylaminofluorene, and of enzymatically activated N-hydroxy-2-acetylaminofluorene with nucleophiles

The interaction of four cellular nucleophiles with the putativeultimate carcinogens N-sulfonoxy-2-[ring-³H]acetylamino-fluorene(N-sulfonoxy-2-AAF) and N-acetoxy-2-[ring-³H] acetylaminofluorene(N-acetoxy-2-AAF), and with N-hydroxy-2-[ring-³H]acetylaminofluorene(N-hydroxy-2-AAF) activated to the ultimate carcinogens by enzymaticsulfonation or trans-acetylation was determined. The adductswere isolated and adduct formation was quantified by isotopedilution. The order of nucleophilicity of the acceptors wasguanosine > tRNA polyguanylic acid (poly G) > N-acetyl-L-methioninewhen N-sulfonoxy-2-AAF, N-acetoxy-2-AAF or N-hydroxy-2- AAFactivated by transacetylation were the electrophiles. In thecase of N-hydroxy-2-AAF activated by enzymatic sulfonation,the order of nucleophilicity was N-acetyl-L-methionine >guanosine tRNA > poly G. The increase in the reactivityof N-acetyl-L-methionine is hypothesized to be due to cytosolicenzyme(s) which facilitate transfer of the methionine residuefrom the nitrogen to carbon atoms 3 and 1 of the fluorene moiety.Of the two synthetic esters, N-sulfonoxy-2- AAF exhibited greaterelectrophilicity than N-acetoxy-2-AAF. The rate of adduct formationof N-sulfonoxy-2-AAF and of N-acetoxy-2-AAF with each nucleophilewas a function of nucleophile concentration, indicative of abimolecular reaction mechanism. The interaction is thought toinvolve attack of the nucleophile on the uncharged ultimatecarcinogen, although interaction with an ion pair cannot beeliminated. The mutagenicity of N-sulfonoxy-2-AAF, N-acetoxy-2-AAFand of enzymatically activated N-hydroxy-2-AAF was evaluatedby the Ames test. N-Sulfonoxy-2-AAF was virtually inactive,while N-acetoxy-2-AAF exhibited weak mutagenicity. N-Hydroxy-2-AAFactivated by enzymatic sulfonation exhibited greater mutagenicitythan synthetic N-sulfonoxy-2-AAF. The mutagenicity and reactivityof ultimate carcinogens derived from N-hydroxy-2-AAF by enzymaticactivation do not necessarily coincide with the mutagenicityand reactivity of the synthetic ultimate carcinogens.     

Reemergence of Scabies Driven by Adolescents and Young Adults,Germany, 2009–2018

To validate anecdotal evidence on scabies infestations, we analyzed inpatient and outpatient claims data in Germany. Scabies diagnoses increased 9-fold and treatment failure 4-fold during 2009–2018, driven mainly by persons 15–24 years of age. Prevention and control in young adults appear key because of these persons’ high mobility and social connectivity.     

Meta-analysis of epigenome-wide association studies of carotid intima-media thickness

Common carotid intima-media thickness (cIMT) is an index of subclinical atherosclerosis that is associated with ischemic stroke and coronary artery disease (CAD). We undertook a cross-sectional epigenome-wide association study (EWAS) of measures of cIMT in 6400 individuals. Mendelian randomization analysis was applied to investigate the potential causal role of DNA methylation in the link between atherosclerotic cardiovascular risk factors and cIMT or clinical cardiovascular disease. The CpG site cg05575921 was associated with cIMT (beta?=??0.0264, p value?=?3.5?×?10^–8) in the discovery panel and was replicated in replication panel (beta?=??0.07, p value?=?0.005). This CpG is located at chr5:81649347 in the intron 3 of the aryl hydrocarbon receptor repressor gene (AHRR). Our results indicate that DNA methylation at cg05575921 might be in the pathway between smoking, cIMT and stroke. Moreover, in a region-based analysis, 34 differentially methylated regions (DMRs) were identified of which a DMR upstream of ALOX12 showed the strongest association with cIMT (p value?=?1.4?×?10^–13). In conclusion, our study suggests that DNA methylation may play a role in the link between cardiovascular risk factors, cIMT and clinical cardiovascular disease.

     

Have you been taking your pills? The adherence-monitoring sequence in the medical interview

This paper employs qualitative, sociolinguistic techniques to identify and describe the kinds of conversational strategies that primary care physicians use to assess patient adherence to antihypertensive regimens. Three general approaches are described: indirect inquiry, simple direct questions, and information-intensive inquiry. The strengths and weaknesses inherent in these discourse categories are discussed. Qualitative assessment, coupled with the results of a pilot study investigating the effectiveness of naturally occurring instances of these three general styles, leads to the conclusion that how one asks "Have you been taking your medications?" is consequential for the accurate diagnosis and management of adherence problems.     

Single-cell fate mapping reveals widespread clonal ignorance of low-affinity T cells exposed to systemic infection

T cell ignorance is a specific form of immunological tolerance. It describes the maintenance of naivety in antigen-specific T cells in vivo despite the presence of their target antigen. It is thought to mainly play a role during the steady state, when self-antigens are presented in absence of costimulatory signals and at low density or to T cells of low affinity. In how far antigen-specific T cells can also remain clonally ignorant to foreign antigens, presented in the inflammatory context of systemic infection, remains unclear. Using single-cell in vivo fate mapping and high throughput flow cytometric enrichment, we find that high-affinity antigen-specific CD8⁺ T cells are efficiently recruited upon systemic infection. In contrast, most low-affinity antigen-specific T cells ignore the priming antigen and persist in the naïve state while remaining fully responsive to subsequent immunization with a high-affinity ligand. These data establish the widespread clonal ignorance of low-affinity T cells as a major factor shaping the composition of antigen-specific CD8⁺ T cell responses to systemic infection.     

Enolase 1 of Candida albicans binds human CD4+ T cells and modulates naïve and memory responses

To obtain a better understanding of the biology behind life-threatening fungal infections caused by Candida albicans, we recently conducted an in silico screening for fungal and host protein interaction partners. We report here that the extracellular domain of human CD4 binds to the moonlighting protein enolase 1 (Eno1) of C. albicans as predicted bioinformatically. By using different anti-CD4 monoclonal antibodies, we determined that C. albicans Eno1 (CaEno1) primarily binds to the extracellular domain 3 of CD4. Functionally, we observed that CaEno1 binding to CD4 activated lymphocyte-specific protein tyrosine kinase (LCK), which was also the case for anti-CD4 monoclonal antibodies tested in parallel. CaEno1 binding to naïve human CD4⁺ T cells skewed cytokine secretion toward a Th2 profile indicative of poor fungal control. Moreover, CaEno1 inhibited human memory CD4⁺ T-cell recall responses. Therapeutically, CD4⁺ T cells transduced with a p41/Crf1-specific T-cell receptor developed for adoptive T-cell therapy were not inhibited by CaEno1 in vitro. Together, the interaction of human CD4⁺ T cells with CaEno1 modulated host CD4⁺ T-cell responses in favor of the fungus. Thus, CaEno1 mediates not only immune evasion through its interference with complement regulators but also through the direct modulation of CD4⁺ T-cell responses.