264 research outputs found
Complete Genome Sequences of vB_LmoS_188 and vB_LmoS_293, Two Bacteriophages with Specificity for Listeria monocytogenes Strains of Serotypes 4b and 4e
peer-reviewedListeria monocytogenes is responsible for the rare disease listeriosis, which is associated with the consumption of contaminated food products. We report here the complete genome sequences of vB_LmoS_188 and vB_LmoS_293, phages isolated from environmental sources and that have host specificity for L. monocytogenes strains of the 4b and 4e serotypes.This work was supported by the EU 7th Framework projects PROMISE
(project no. 265877) and FOODSEG (project no. 266061) and by a safefood
mini-project
Role of interactions in ferrofluid thermal ratchets
Orientational fluctuations of colloidal particles with magnetic moments may
be rectified with the help of external magnetic fields with suitably chosen
time dependence. As a result a noise-driven rotation of particles occurs giving
rise to a macroscopic torque per volume of the carrier liquid. We investigate
the influence of mutual interactions between the particles on this ratchet
effect by studying a model system with mean-field interactions. The stochastic
dynamics may be described by a nonlinear Fokker-Planck equation for the
collective orientation of the particles which we solve approximately by using
the effective field method. We determine an interval for the ratio between
coupling strength and noise intensity for which a self-sustained rectification
of fluctuations becomes possible. The ratchet effect then operates under
conditions for which it were impossible in the absence of interactions.Comment: 18 pages, 10 figure
Outpatient visit modality and parallel patient satisfaction: A multi-site cohort analysis of telemedicine and in-person visits during the COVID-19 pandemic
Telemedicine approaches provide many benefits to patients across both primary and specialty care. Patient acceptance is imperative to successful telemedicine implementation. As telemedicine utilization continues to surge, it is imperative that healthcare organizations have a method for evaluating the patient experience with these types of visits. Previous studies on experience with telemedicine have focused on smaller patient populations with narrow inclusion criteria and limited geographical reach. This research described how patients’ satisfaction with video telemedicine-based visits varied based on patient characteristics and how they compare with in-person visits. We obtained and analyzed results from standardized patient experience surveys to compare telemedicine and in-person clinic visits during the COVID-19 pandemic (between July 1, 2020, and June 30, 2021) across a diverse patient population. During the study timeframe, surveys were sent to 1,521,398 patients with a response rate of 20% (307,185). Our organization’s unique structure, size, and geographic spread allowed for a deeper and more comprehensive examination of telemedicine participants. Though a few trends emerged in the results, there were no significant differences in patient ratings of telemedicine visits and in-person clinic visits during the same period (p=0.672). This study demonstrated that patient satisfaction with telemedicine visits was non-inferior to in-person outpatient visits during the study timeframe.
Experience Framework
This article is associated with the Innovation & Technology lens of The Beryl Institute Experience Framework (https://www.theberylinstitute.org/ExperienceFramework). Access other PXJ articles related to this lens. Access other resources related to this len
Comparative Genomic Analysis of Two Serotype 1/2b Listeria monocytogenes Isolates from Analogous Environmental Niches Demonstrates the Influence of Hypervariable Hotspots in Defining Pathogenesis
The vast majority of clinical human listeriosis cases are caused by serotype 1/2a, 1/2b, 1/2c, and 4b isolates of Listeria monocytogenes. The ability of L. monocytogenes to establish a systemic listeriosis infection within a host organism relies on a combination of genes that are involved in cell recognition, internalization, evasion of host defenses, and in vitro survival and growth. Recently, whole genome sequencing and comparative genomic analysis have proven to be powerful tools for the identification of these virulence-associated genes in L. monocytogenes. In this study, two serotype 1/2b strains of L. monocytogenes with analogous isolation sources, but differing infection abilities, were subjected to comparative genomic analysis. The results from this comparison highlight the importance of accessory genes (genes that are not part of the conserved core genome) in L. monocytogenes pathogenesis. In addition, a number of factors, which may account for the perceived inability of one of the strains to establish a systemic infection within its host, have been identified. These factors include the notable absence of the Listeria pathogenicity island 3 and the stress survival islet, of which the latter has been demonstrated to enhance the survival ability of L. monocytogenes during its passage through the host intestinal tract, leading to a higher infection rate. The findings from this research demonstrate the influence of hypervariable hotspots in defining the physiological characteristics of a L. monocytogenes strain and indicate that the emergence of a non-pathogenic isolate of L. monocytogenes may result from a cumulative loss of functionality rather than by a single isolated genetic event
On Differences of Zeta Values
Finite differences of values of the Riemann zeta function at the integers are
explored. Such quantities, which occur as coefficients in Newton series
representations, have surfaced in works of Maslanka, Coffey, Baez-Duarte, Voros
and others. We apply the theory of Norlund-Rice integrals in conjunction with
the saddle point method and derive precise asymptotic estimates. The method
extends to Dirichlet L-functions and our estimates appear to be partly related
to earlier investigations surrounding Li's criterion for the Riemann
hypothesis.Comment: 18 page
Whole genome sequence analysis; an improved technology that identifies underlying genotypic differences between closely related Listeria monocytogenes strains
peer-reviewedAs the new technology of whole genome sequencing (WGS) has been shown to have greater discriminatory power in differentiating strains than the much-used pulsed-field gel electrophoresis (PFGE), there is currently a transition from using PFGE to WGS for disease outbreak investigation. Therefore, there is a need for comparison of bacterial isolates using both PFGE and WGS. In this study, two pairs of L. monocytogenes strains with geographically diverse sources of isolation but which had indistinguishable or closely related PFGE profiles, were subjected to WGS analysis. Comparative analysis of their genomes showed that one pair of strains which had closely related PFGE profiles in fact differed significantly from one another in terms of their antibiotic and heavy metal stress resistance determinants, and mobile genetic elements. Therefore, this research demonstrated the ability of WGS analysis to differentiate very closely related strains and that WGS analysis represents the most effective tool available for subtyping L. monocytogenes isolates
Inhibition of L. monocytogenes Biofilm Formation by the Amidase Domain of the Phage vB_LmoS_293 Endolysin
peer-reviewedListeria monocytogenes is a ubiquitous Gram-positive bacterium that is a major concern for food business operators because of its pathogenicity and ability to form biofilms in food production environments. Bacteriophages (phages) have been evaluated as biocontrol agents for L. monocytogenes in a number of studies and, indeed, certain phages have been approved for use as anti-listerial agents in food processing environments (ListShield and PhageGuard Listex). Endolysins are proteins produced by phages in the host cell. They cleave the peptidoglycan cell wall, thus allowing release of progeny phage into the environment. In this study, the amidase domain of the phage vB_LmoS_293 endolysin (293-amidase) was cloned and expressed in Escherichia. coli(E. coli). Muralytic activity at different concentrations, pH and temperature values, lytic spectrum and activity against biofilms was determined for the purified 293-amidase protein. The results showed activity on autoclaved cells at three different temperatures (20 °C, 37 °C and 50 °C), with a wider specificity (L. monocytogenes 473 and 3099, a serotype 4b and serogroup 1/2b-3b-7, respectively) compared to the phage itself, which targets only L. monocytogenes serotypes 4b and 4e. The protein also inhibits biofilm formation on abiotic surfaces. These results show the potential of using recombinant antimicrobial proteins against pathogens in the food production environment
Effectiveness of current hygiene practices on minimization of Listeria monocytogenes in different mushroom production‐related environments
peer-reviewedBackground: The commercial production of Agaricus bisporus is a three stage process:
1) production of compost, also called “substrate”; 2) production of casing soil; and
3) production of the mushrooms. Hygiene practices are undertaken at each stage:
pasteurization of the substrate, hygiene practices applied during the production of
casing soil, postharvest steam cookout, and disinfection at the mushroom production
facilities. However, despite these measures, foodborne pathogens, including Listeria
monocytogenes, are reported in the mushroom production environment. In this work,
the presence of L. monocytogenes was evaluated before and after the application of
hygiene practices at each stage of mushroom production with swabs, samples of
substrate, casing, and spent mushroom growing substrates.
Results: L. monocytogenes was not detected in any casing or substrate sample by enumeration according to BS EN ISO 11290-2:1998. Analysis of the substrate showed
that L. monocytogenes was absent in 10 Phase II samples following pasteurization,
but was then present in 40% of 10 Phase III samples. At the casing production facility, 31% of 59 samples were positive. Hygiene improvements were applied, and
after four sampling occasions, 22% of 37 samples were positive, but no statistically
significant difference was observed (p > .05). At mushroom production facilities, the
steam cookout process inactivated L. monocytogenes in the spent growth substrate,
but 13% of 15 floor swabs at Company 1 and 19% of 16 floor swabs at Company 2,
taken after disinfection, were positive.
Conclusion: These results showed the possibility of L. monocytogenes recontamination of Phase III substrate, cross-contamination at the casing production stage and
possible survival after postharvest hygiene practices at the mushroom growing facilities. This information will support the development of targeted measures to minimize
L. monocytogenes in the mushroom industry.Food Institutional Research Measur
Neurobiological Mechanisms That Contribute to Stress-related Cocaine Use
The ability of stressful life events to trigger drug use is particularly problematic for the management of cocaine addiction due to the unpredictable and often uncontrollable nature of stress. For this reason, understanding the neurobiological processes that contribute to stress-related drug use is important for the development of new and more effective treatment strategies aimed at minimizing the role of stress in the addiction cycle. In this review we discuss the neurocircuitry that has been implicated in stress-induced drug use with an emphasis on corticotropin releasing factor actions in the ventral tegmental area (VTA) and an important pathway from the bed nucleus of the stria terminalis to the VTA that is regulated by norepinephrine via actions at beta adrenergic receptors. In addition to the neurobiological mechanisms that underlie stress-induced cocaine seeking, we review findings suggesting that the ability of stressful stimuli to trigger cocaine use emerges and intensifies in an intake-dependent manner with repeated cocaine self-administration. Further, we discuss evidence that the drug-induced neuroadaptations that are necessary for heightened susceptibility to stress-induced drug use are reliant on elevated levels of glucocorticoid hormones at the time of cocaine use. Finally, the potential ability of stress to function as a “stage setter” for drug use – increasing sensitivity to cocaine and drug-associated cues – under conditions where it does not directly trigger cocaine seeking is discussed. As our understanding of the mechanisms through which stress promotes drug use advances, the hope is that so too will the available tools for effectively managing addiction, particularly in cocaine addicts whose drug use is stress-driven
Exome sequencing identifies NBEAL2 as the causative gene for gray platelet syndrome.
Gray platelet syndrome (GPS) is a predominantly recessive platelet disorder that is characterized by mild thrombocytopenia with large platelets and a paucity of α-granules; these abnormalities cause mostly moderate but in rare cases severe bleeding. We sequenced the exomes of four unrelated individuals and identified NBEAL2 as the causative gene; it has no previously known function but is a member of a gene family that is involved in granule development. Silencing of nbeal2 in zebrafish abrogated thrombocyte formation
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