In this hypothesis, we address the biological/immunological pathway leading to severe disease or death after infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The underlying immune response is described with "original antigenic sin" (OAS) whereby previous infections influence the response to future virus encounters. We cite evidence for OAS-induced immunopathology in HIV-1 disease. We hypothesize that similar immune abnormalities can occur after infection with SARS-CoV-2. This hypothesis is supported by recent analysis of the antibodies in infected patients demonstrating serological and B cell abnormalities. The concept of symmetrical clonal regulation developed earlier for the immune network illustrates the pathway suggested by our hypothesis and may be helpful to develop strategies avoiding severe coronavirus disease 2019.Amphibian locomotor capacity is strongly linked to temperature and hydration. However, organisms in nature experience covariation of multiple environmental factors, and thus to better understand the effects of thermal and hydric conditions on physiological performance, it is critical not only to experimentally disentangle them but also to incorporate potential interactive effects due to geographic variation. To this end, we selected two populations of the small amphibian Pleurodema thaul inhabiting highly contrasting temperatures and precipitation regimens. With these two populations, we evaluated the thermal and hydric sensitivities of locomotor performance. For both factors, performance increased with temperature as well as with hydration level, although performance reached a plateau between 25° and 30°C. In addition, the influence of dehydration on performance was independent of the temperature at which it was tested. Our results also showed that the population from the warmer environment has lower sensitivity of locomotor performance to dehydration, probably as a consequence of thermal adaptation, although further studies might be required to fully understand this.The life cycle of gobies of the Sicydiinae subfamily depends on climbing waterfalls. Two sympatric sicydiines species from Reunion Island, Sicyopterus lagocephalus (SIL) and Cotylopus acutipinnis (COA), employ different climbing modes. SIL uses a steady "inching" mode interrupted by short rest periods, whereas COA exhibits short "power-burst" undulatory movements punctuated by longer rest periods. Consequently, we explored the relationship between climbing performance and metabolic activity in these two species. We demonstrated that the two climbing modes are supported by different ecophysiological profiles that promote the interspecific variability of locomotor performance. More specifically, SIL performed better than COA during a climbing experiment because of its inching climbing mode, supported by a generally greater metabolic capacity and a higher potential for oxidative metabolism. Interestingly, we did not detect any difference in metabolic fuel storage and lactate production during climbing in either species, suggesting that these species can maintain fuel reserves and limit lactate accumulation through extensive rest times. Overall, this study provides new insights into the ecophysiology of these two emblematic species and suggests that the better climbing capacity of SIL is supported by its muscular metabolic capacity.Enterococcus faecium is a lactic acid bacterium with applications in food engineering and nutrigenomics, including as starter cultures in fermented foods. To differentiate the E. faecium probiotic from pathogenic bacteria, physiological analyses are often used but they do not guarantee that a bacterial strain is not pathogenic. We report here new findings and an approach based on comparison of the genetic mobility of (1) probiotic, (2) pathogenic, and (3) nonpathogenic and non-probiotic strains, so as to differentiate probiotics, and inform their safe use.  https://www.selleckchem.com/peptide/tirzepatide-ly3298176.html  The region of the 16S ribosomal DNA (rDNA) genes of different E. faecium strains native to Pernambuco-Brazil was used with the GenBank query sequence. Complete genomes were selected and divided into three groups as noted above to identify the mobile genetic elements (MGEs) (transposase, integrase, conjugative transposon protein and phage) and antibiotic resistance genes (ARGs), and to undertake pan-genome analysis and multiple genome alignment. Differences in the number of MGEs were found in ARGs, in the presence and absence of the genes that differentiate E. faecium probiotics and pathogenic bacteria genetically. Our data suggest that genetic mobility appears to be informative in differentiating between probiotic and pathogenic strains. While the present findings are not necessarily applicable to all probiotics, they offer novel molecular insights to guide future research in nutrigenomics, clinical medicine, and food engineering on new ways to differentiate pathogenic from probiotic bacteria.Very few antimicrobial agents remain active against Pseudomonas aeruginosa and Klebsiella pneumoniae in some geographic regions. We evaluated the in vitro activity of ceftazidime-avibactam, ceftolozane-tazobactam, and comparator agents against 6,210 P. aeruginosa and 6,041 K. pneumoniae isolates consecutively collected from 85 U.S. medical centers across 37 states in 2016-2018. Antimicrobial susceptibility was determined by reference broth microdilution method. K. pneumoniae isolates found to have elevated MICs for broad-spectrum cephalosporins were submitted to whole-genome sequencing analysis to detect resistance genes. Ceftazidime-avibactam (97.1% susceptible [S]) and ceftolozane-tazobactam (97.0%S) were the most active compounds against P. aeruginosa and retained activity against meropenem-nonsusceptible (88.5-89.0%S), piperacillin-tazobactam-nonsusceptible (86.6-87.0%S), and other resistant subsets of isolates. The most active agents against K. pneumoniae per CLSI criteria were ceftazidime-avibactam (>99.9%S), amikacin (98.4%S), and meropenem (97.1%S). Ceftolozane-tazobactam was active against 95.3% of K. pneumoniae but showed limited activity against extended-spectrum β-lactamase and carbapenemase producers (82.9% and 0.0%S, respectively).