Contact tracing is a key component of successful management of COVID-19. Contacts of infected individuals are asked to quarantine, which can significantly slow down (or prevent) community spread. ...Contact tracing is particularly effective when infections are detected quickly, when contacts are traced with high probability, when the initial number of cases is low, and when social distancing and border restrictions are in place. However, the magnitude of the individual contribution of these factors in reducing epidemic spread and the impact of population immunity (due to either previous infection or vaccination), in determining contact tracing outputs is not fully understood. We present a delayed differential equation model to investigate how the immunity status and the relaxation of social distancing requirements affect contact tracing practices. We investigate how the minimal contact tracing efficiency required to keep an outbreak under control depends on the contact rate and on the proportion of immune individuals. Additionally, we consider how delays in outbreak detection and increased case importation rates affect the number of contacts to be traced daily. We show that in communities that have reached a certain immunity status, a lower contact tracing efficiency is required to avoid a major outbreak, and delayed outbreak detection and relaxation of border restrictions do not lead to a significantly higher risk of overwhelming contact tracing. We find that investing in testing programs, rather than increasing the contact tracing capacity, has a larger impact in determining whether an outbreak will be controllable. This is because early detection activates contact tracing, which will slow, and eventually reverse exponential growth, while the contact tracing capacity is a threshold that will easily become overwhelmed if exponential growth is not curbed. Finally, we evaluate quarantine effectiveness in relation to the immunity status of the population and for different viral variants. We show that quarantine effectiveness decreases with increasing proportion of immune individuals, and increases in the presence of more transmissible variants. These results suggest that a cost-effective approach is to establish different quarantine rules for immune and nonimmune individuals, where rules should depend on viral transmissibility after vaccination or infection. Altogether, our study provides quantitative information for contact tracing downsizing in vaccinated populations or in populations that have already experienced large community outbreaks, to guide COVID-19 exit strategies.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Public health responses to the COVID-19 pandemic varied across the world. Some countries (e.g. mainland China, New Zealand and Taiwan) implemented elimination strategies involving strict travel ...measures and periods of rigorous non-pharmaceutical interventions (NPIs) in the community, aiming to achieve periods with no disease spread; while others (e.g. many European countries and the USA) implemented mitigation strategies involving less strict NPIs for prolonged periods, aiming to limit community spread. Travel measures and community NPIs have high economic and social costs, and there is a need for guidelines that evaluate the appropriateness of an elimination or mitigation strategy in regional contexts. To guide decisions, we identify key criteria and provide indicators and visualizations to help answer each question. Considerations include determining whether disease elimination is: (1) necessary to ensure healthcare provision; (2) feasible from an epidemiological point of view and (3) cost-effective when considering, in particular, the economic costs of travel measures and treating infections. We discuss our recommendations by considering the regional and economic variability of Canadian provinces and territories, and the epidemiological characteristics of different SARS-CoV-2 variants. While elimination may be a preferable strategy for regions with limited healthcare capacity, low travel volumes, and few ports of entry, mitigation may be more feasible in large urban areas with dense infrastructure, strong economies, and with high connectivity to other regions.
Despite our growing knowledge about the pathomechanisms of cancer cachexia, a whole clinical picture of the cachectic patient is still missing. Our objective was to evaluate the clinical ...characteristics in cancer patients with and without cachexia to get the whole picture of a cachectic patient.
Cancer patients of the University Clinic "Klinikum rechts der Isar" with gastrointestinal, gynecological, hematopoietic, lung and some other tumors were offered the possibility to take part in the treatment concept including a nutrition intervention and an individual training program according to their capability. We now report on the first 503 patients at the time of inclusion in the program between March 2011 and October 2015. We described clinical characteristics such as physical activity, quality of life, clinical dates and food intake.
Of 503 patients with cancer, 131 patients (26.0%) were identified as cachectic, 369 (73.4%) as non-cachectic. The change in cachexia were 23% reduced capacity performance (108 Watt for non-cachectic-patients and 83 Watt for cachectic patients) and 12% reduced relative performance (1.53 Watt/kg for non-cachectic and 1.34 Watt/kg for cachectic patients) in ergometry test. 75.6% of non-cachectic and 54.3% of cachectic patients still received curative treatment.
Cancer cachectic patients have multiple symptoms such as anemia, impaired kidney function and impaired liver function with elements of mild cholestasis, lower performance and a poorer quality of life in the EORTC questionnaire. Our study reveals biochemical and clinical specific features of cancer cachectic patients.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The liver is considered to be the major site of first-pass metabolism, but the small intestine is also able to contribute significantly. The improvement of existing in vitro techniques and the ...development of new ones, such as intestinal slices, allow a better understanding of the intestine as a metabolic organ. In this paper, the formation of metabolites of several human CYP3A substrates by liver and intestinal slices from rat and mouse was compared. The results show that liver slices exhibited a higher metabolic rate for the majority of the studied substrates, but some metabolites were produced at a higher rate by intestinal slices, compared with liver slices. Coincubation with ketoconazole inhibited the metabolic conversion in intestinal slices almost completely, but inhibition was variable in liver slices. To better understand the role of CYP3A in mice, we studied the relative mRNA expression of different CYP3A isoforms in intestine and liver from mice because, in this species, CYP3A expression has not been well described in these organs. It was found that in mice, CYP3A13 is more expressed in the intestine, whereas CYP3A11, CYP3A25, and CYP3A41 are more expressed in the liver, comparable to similar findings in the rat. Altogether, these data demonstrate that, in addition to liver, the intestine from mouse and rat may have an important role in the process of first-pass metabolism, depending on the substrate. Moreover, we show that intestinal slices are a useful in vitro technique to study gut metabolism.
Abstract Purpose The purpose of this study was to report on the first experiences with freehand single-photon emission-computed tomography (freehand SPECT) in sentinel lymph node biopsy (SLNB) in ...patients with malignant melanoma. Freehand SPECT is a novel imaging modality combining gamma probes, surgical navigation systems, and emission tomography algorithms, designed to overcome some of the limitations of conventional gamma probes. Methods In this study 20 patients with malignant melanoma underwent conventional planar scintigraphy prior to surgery. In the operating room, the number and location of separable SLNs were detected first by a pre-incisional scan with freehand SPECT to render a 3D-image of the target site and afterwards by a scan with a conventional gamma probe. After SLNB another scan was performed to document the removal of all targeted SLNs. Results Planar scintigraphy identified 40 SLNs in 26 nodal basins. Pre-incisional freehand SPECT mapped 38 of these nodes as well as one additional node in one patient (95.0% node based sensitivity). The results of freehand SPECT were identical to those of planar scintigraphy in 25 basins, while it missed one basin (96.2% basin based sensitivity). In comparison, the gamma probe failed to detect 7 nodes in 4 basins (82.5% node based sensitivity and 84.6% basin based sensitivity). After resection freehand SPECT detected 9 remaining radioactive spots, two of whichwere resected as they matched the position of SLNs detected on preoperative planar scintigraphy. Conclusions Freehand SPECT provides a real-time, intraoperative 3D-image of the radioactive labelled SLNs, facilitating their detection and resection.
The evolution of mutualism between host and symbiont communities plays an essential role in maintaining ecosystem function and should therefore have a profound effect on their range expansion ...dynamics. In particular, the presence of mutualistic symbionts at the leading edge of a host-symbiont community should enhance its propagation in space. We develop a theoretical framework that captures the eco-evolutionary dynamics of host-symbiont communities, to investigate how the evolution of resource exchange may shape community structure during range expansion. We consider a community with symbionts that are mutualistic or parasitic to various degrees, where parasitic symbionts receive the same amount of resource from the host as mutualistic symbionts, but at a lower cost. The selective advantage of parasitic symbionts over mutualistic ones is increased with resource availability (i.e. with host density), promoting mutualism at the range edges, where host density is low, and parasitism at the population core, where host density is higher. This spatial selection also influences the speed of spread. We find that the host growth rate (which depends on the average benefit provided by the symbionts) is maximal at the range edges, where symbionts are more mutualistic, and that host-symbiont communities with high symbiont density at their core (e.g. resulting from more mutualistic hosts) spread faster into new territories. These results indicate that the expansion of host-symbiont communities is pulled by the hosts but pushed by the symbionts, in a unique push-pull dynamic where both the host and symbionts are active and tightly-linked players.
•We present the first CCD observations of TYCHO 3836-0854-1 and TYCHO 4157-0683-1.•They are other two examples of deep low-mass ratio (DLMR) overcontact binary stars.•Both the systems may be possible ...progenitors of merging stars, like V1309 sco.•The absolute dimensions of the systems are estimated.
Here we present the first CCD multi-color B, V and Ic light curves of the eclipsing binary stars TYC 3836-0854-1 and TYC 4157-0683-1, the data were obtained in four nights in the year 2010 and three nights in the year 2012 for the first one and in four nights in the year 2010 for the second one. Based on our data the short orbital periods of the systems are confirmed and revised to P=0.4155590days for TYC 3836-0854-1 and P=0.3960676days for TYC 4157-0683-1. Our observations of TYC 3836-0854-1 show symmetric light curves in all passbands with brightness in both maxima at the same level, while the light curve of TYC 4157-0683-1 appear to exhibit the typical O’Connell effect, with Maximum I brighter than Maximum II. By analyzing simultaneously the complete light curves with the 2003 version of the Wilson–Devinney code (2005 revision), photometric solutions were determined. Both the systems shows a small difference between the components temperatures of ΔT=14K for TYC 3836-0854-1 and ΔT =149K for TYC 4157-0683-1. The orbital inclination is i=78°.6 and i=79°.7 respectively. The systems are found to be a high fill-out, extreme mass ratio overcontact binary with a mass ratio of q = 0.206 and a fill-out factor of f=59.2% for TYC 3836-0854-1 and q=0.150 and a fill-out factor of f=76.3% for TYC 4157-0683-1, suggesting that both the systems are in the late stage of overcontact evolution.
It is known that deep (f>50%), low-mass ratio (q<0.25) overcontact binary stars (DLMR) are a very important resource for understanding the phenomena of Blue Straggler/FK Com-type stars that is an unsolved problem in stellar astrophysics. One of the possible explanations for their formation is from the coalescence of W UMa-type overcontact binary systems. The absolute dimensions of both the systems are estimated from the logTeff - logL diagram and their dynamical evolution is inferred.
Biodiversity is an important component of healthy ecosystems, and thus understanding the mechanisms behind species coexistence is critical in ecology and conservation biology. In particular, few ...studies have focused on the dynamics resulting from the co-occurrence of mutualistic and competitive interactions within a group of species. Here we build a mathematical model to study the dynamics of a guild of competitors who are also engaged in mutualistic interactions with a common partner. We show that coexistence as well as competitive exclusion can occur depending on the competition strength and on strength of the mutualistic interactions, and we formulate concrete criteria for predicting invasion success of an alien mutualist based on propagule pressure, alien traits (such as its resource exchange ability) and composition of the recipient community. We find that intra guild diversity promotes the coexistence of species that would otherwise competitively exclude each other, and makes a guild less vulnerable to invasion. Our results can serve as a useful framework to predict the consequences of species manipulation in mutualistic communities.
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