scholarly journals Two Properties of a Gene-for-Gene Coevolution System under Human Perturbations

1999 ◽  
Vol 89 (9) ◽  
pp. 811-816 ◽  
Author(s):  
P. Sun ◽  
X. B. Yang
Keyword(s):  
Real World ◽  
Host Population ◽  
Resistant Genotype ◽  
Human Perturbation ◽  
Boom And Bust ◽  
Human Perturbations ◽  
Pathogen Populations ◽  
Host Parasite ◽  
Over Time ◽  
Gene For Gene

Recently, the gene-for-gene host-parasite coevolution model of Leonard was extended by incorporating two kinds of perturbations. The first kind was the natural perturbations that include those caused by pathogen migration between the two subpopulations of the host, forward and backward mutations in the host or pathogen populations, and some others. The second kind was human perturbations, such as constantly increasing the percentage of the resistant genotype within the host population each season. In this study, we quantitatively compared the two kinds of perturbations and extended the constantly changing human perturbation to include non-constant perturbations that are more likely to occur in the real world. Two properties of the modified Leonard model were revealed from this study. First, when both human perturbations and natural perturbations are involved, the effects of natural perturbations are very small compared with those of human perturbations. This finding ensures that, in the study of human perturbations, we can simplify the study by ignoring the effects of natural perturbations. Second, through the simulation of nonconstant perturbations, which assumes that the proportion of the resistant genotype of the host population increases over time, we found that the model reproduces the “boom and bust” epidemic cycles that are often found in agroecosystems.

Gene-for-gene relationships in the Avena: Puccinia graminis host–parasite system in Canada

1970 ◽  
Vol 48 (5) ◽  
pp. 969-975 ◽  
Author(s):  
J. W. Martens ◽  
R. I. H. McKenzie ◽  
G. J. Green
Keyword(s):  
North America ◽  
Resistance Genes ◽  
Stem Rust ◽  
Host Population ◽  
Puccinia Graminis ◽  
Physiologic Race ◽  
Host Genotype ◽  
Physiologic Races ◽  
Host Parasite ◽  
Gene For Gene

The results of 48 years of oat stem rust physiologic race surveys are interpreted in terms of the prevailing host genotype. Changes in the frequencies of genes that govern virulence in the pathogen can be explained only in part by changes in the resistance genes carried by the host population. Genes for virulence on newly released types of resistance have spread very quickly through the rust population, after initial 'breakdown' of the resistance. The most successful physiologic races carry genes for virulence in excess of those required for successful parasitism in North America. Many races carry genes for virulence on types of resistance that have never been used on this continent.

scholarly journals Real World Performance Evaluation of Transcatheter Aortic Valve Implantation

2021 ◽  
Vol 10 (9) ◽  
pp. 1890
Author(s):  
Gabriele Pesarini ◽  
Gabriele Venturi ◽  
Domenico Tavella ◽  
Leonardo Gottin ◽  
Mattia Lunardi ◽  
...  
Keyword(s):  
Aortic Valve ◽  
Real World ◽  
Baseline Risk ◽  
Risk Scores ◽  
World Population ◽  
Control Analysis ◽  
Transcatheter Aortic Valve ◽  
Procedural Control ◽  
Risk Patients ◽  
Over Time

Background: The aim of this research is to describe the performance over time of transcatheter aortic valve implantations (TAVIs) in a high-volume center with a contemporary, real-world population. Methods: Patients referred for TAVIs at the University Hospital of Verona were prospectively enrolled. By cumulative sum failures analysis (CUSUM), procedural-control curves for standardized combined endpoints—as defined by the Valve Academic Research Consortium-2 (VARC-2)—were calculated and analyzed over time. Acceptable and unacceptable limits were derived from recent studies on TAVI in intermediate and low-risk patients to fit the higher required standards for current indications. Results: A total of 910 patients were included. Baseline risk scores significantly reduced over time. Complete procedural control was obtained after approximately 125 and 190 cases for device success and early safety standardized combined endpoints, respectively. High risk patients (STS ≥ 8) had poorer outcomes, especially in terms of VARC-2 clinical efficacy, and required a higher case load to maintain in-control and proficient procedures. Clinically relevant single endpoints were all influenced by operator’s experience as well. Conclusions: Quality-control analysis for contemporary TAVI interventions based on standardized endpoints suggests the need for relevant operator’s experience to achieve and maintain optimal clinical results, especially in higher-risk subjects.

scholarly journals POS0619 MODELLING OF DISEASE ACTIVITY IN PATIENTS WITH INFLAMMATORY ARTHROPATHIES TREATED WITH ETANERCEPT ORIGINATOR OR BIOSIMILAR AS FIRST-LINE BIOLOGIC IN AN AUSTRALIAN REAL-WORLD DATASET

2021 ◽  
Vol 80 (Suppl 1) ◽  
pp. 547.1-547
Author(s):  
C. Deakin ◽  
G. Littlejohn ◽  
H. Griffiths ◽  
T. Smith ◽  
C. Osullivan ◽  
...  
Keyword(s):  
Disease Activity ◽  
Clinical Data ◽  
Real World ◽  
Rank Test ◽  
P Value ◽  
Continuous Variables ◽  
Linear Quadratic ◽  
First Line ◽  
Modest Improvement ◽  
Over Time

Background:The availability of biosimilars as non-proprietary versions of established biologic disease-modifying anti-rheumatic drugs (bDMARDs) is enabling greater access for patients with rheumatic diseases to effective medications at a lower cost. Since April 2017 both the originator and a biosimilar for etanercept (trade names Enbrel and Brenzys, respectively) have been available for use in Australia.Objectives:[1]To model effectiveness of etanercept originator or biosimilar in reducing Disease Activity Score 28-joint count C reactive protein (DAS28CRP) in patients with rheumatoid arthritis (RA), psoriatic arthritis (PsA) or ankylosing spondylitis (AS) treated with either drug as first-line bDMARD[2]To describe persistence on etanercept originator or biosimilar as first-line bDMARD in patients with RA, PsA or ASMethods:Clinical data were obtained from the Optimising Patient outcomes in Australian rheumatoLogy (OPAL) dataset, derived from electronic medical records. Eligible patients with RA, PsA or AS who initiated etanercept originator (n=856) or biosimilar (n=477) as first-line bDMARD between 1 April 2017 and 31 December 2020 were identified. Propensity score matching was performed to select patients on originator (n=230) or biosimilar (n=136) with similar characteristics in terms of diagnosis, disease duration, joint count, age, sex and concomitant medications. Data on clinical outcomes were recorded at 3 months after baseline, and then at 6-monthly intervals. Outcomes data that were missing at a recorded visit were imputed.Effectiveness of the originator, relative to the biosimilar, for reducing DAS28CRP over time was modelled in the matched population using linear mixed models with both random intercepts and slopes to allow for individual heterogeneity, and weighting of individuals by inverse probability of treatment weights to ensure comparability between treatment groups. Time was modelled as a combination of linear, quadratic and cubic continuous variables.Persistence on the originator or biosimilar was analysed using survival analysis (log-rank test).Results:Reduction in DAS28CRP was associated with both time and etanercept originator treatment (Table 1). The conditional R-squared for the model was 0.31. The average predicted DAS28CRP at baseline, 3 months, 6 months, 9 months and 12 months were 4.0 and 4.4, 3.1 and 3.4, 2.6 and 2.8, 2.3 and 2.6, and 2.2 and 2.4 for the originator and biosimilar, respectively, indicating a clinically meaningful effect of time for patients on either drug and an additional modest improvement for patients on the originator.Median time to 50% of patients stopping treatment was 25.5 months for the originator and 24.1 months for the biosimilar (p=0.53). An adverse event was the reason for discontinuing treatment in 33 patients (14.5%) on the originator and 18 patients (12.9%) on the biosimilar.Conclusion:Analysis using a large national real-world dataset showed treatment with either the etanercept originator or the biosimilar was associated with a reduction in DAS28CRP over time, with the originator being associated with a further modest reduction in DAS28CRP that was not clinically significant. Persistence on treatment was not different between the two drugs.Table 1.Respondent characteristics.Fixed EffectEstimate95% Confidence Intervalp-valueTime (linear)0.900.89, 0.911.5e-63Time (quadratic)1.011.00, 1.011.3e-33Time (cubic)1.001.00, 1.007.1e-23Originator0.910.86, 0.960.0013Acknowledgements:The authors acknowledge the members of OPAL Rheumatology Ltd and their patients for providing clinical data for this study, and Software4Specialists Pty Ltd for providing the Audit4 platform.Supported in part by a research grant from Investigator-Initiated Studies Program of Merck & Co Inc, Kenilworth, NJ, USA. The opinions expressed in this paper are those of the authors and do not necessarily represent those of Merck & Co Inc, Kenilworth, NJ, USA.Disclosure of Interests:Claire Deakin: None declared, Geoff Littlejohn Consultant of: Over the last 5 years Geoffrey Littlejohn has received educational grants and consulting fees from AbbVie, Bristol Myers Squibb, Eli Lilly, Gilead, Novartis, Pfizer, Janssen, Sandoz, Sanofi and Seqirus., Hedley Griffiths Consultant of: AbbVie, Gilead, Novartis and Lilly., Tegan Smith: None declared, Catherine OSullivan: None declared, Paul Bird Speakers bureau: Eli Lilly, abbvie, pfizer, BMS, UCB, Gilead, Novartis

scholarly journals Friendship paradox in growth networks: analytical and empirical analysis

2021 ◽  
Vol 6 (1) ◽  
Author(s):  
Sergei P. Sidorov ◽  
Sergei V. Mironov ◽  
Alexey A. Grigoriev
Keyword(s):  
Real World ◽  
Preferential Attachment ◽  
Empirical Studies ◽  
Mean Field ◽  
Network Models ◽  
Average Degree ◽  
Closure Model ◽  
Triadic Closure ◽  
Attachment Mechanism ◽  
Over Time

AbstractMany empirical studies have shown that in social, citation, collaboration, and other types of networks in real world, the degree of almost every node is less than the average degree of its neighbors. This imbalance is well known in sociology as the friendship paradox and states that your friends are more popular than you on average. If we introduce a value equal to the ratio of the average degree of the neighbors for a certain node to the degree of this node (which is called the ‘friendship index’, FI), then the FI value of more than 1 for most nodes indicates the presence of the friendship paradox in the network. In this paper, we study the behavior of the FI over time for networks generated by growth network models. We will focus our analysis on two models based on the use of the preferential attachment mechanism: the Barabási–Albert model and the triadic closure model. Using the mean-field approach, we obtain differential equations describing the dynamics of changes in the FI over time, and accordingly, after obtaining their solutions, we find the expected values of this index over iterations. The results show that the values of FI are decreasing over time for all nodes in both models. However, for networks constructed in accordance with the triadic closure model, this decrease occurs at a much slower rate than for the Barabási–Albert graphs. In addition, we analyze several real-world networks and show that their FI distributions follow a power law. We show that both the Barabási–Albert and the triadic closure networks exhibit the same behavior. However, for networks based on the triadic closure model, the distributions of FI are more heavy-tailed and, in this sense, are closer to the distributions for real networks.

The effect of the acanthocephalan Pomphorhynchus laevis upon the respiration of its intermediate host, Gammarus pulex

Parasitology ◽  
1974 ◽  
Vol 68 (2) ◽  
pp. 271-284 ◽  
Author(s):  
A. E. Rumpus ◽  
C. R. Kennedy
Keyword(s):  
Oxygen Consumption ◽  
Oxygen Uptake ◽  
Host Population ◽  
Gammarus Pulex ◽  
Multiple Infections ◽  
Pomphorhynchus Laevis ◽  
Respiration Rates ◽  
Physiological Processes ◽  
Stage Of Development ◽  
Host Parasite

The respiration rates of individual Gammarus pulex infected by larval Pomphorhynchus laevis were investigated with particular reference to the stage of development of the host and parasite and to the water temperature. At 20°C the oxygen consumption of Gammarus of all sizes was reduced by an average of 19·3 % by the presence of cystacanths of the parasite, but was unaffected by the presence of acanthellae. It is considered that the small size of this larval stage, in relation to that of its host, is responsible for the failure to detect an effect. Multiple infections did not exert any greater effect upon host respiration than single cystacanths, nor did it appear that the parasite had different effects upon hosts of different sexes. At 10°C no significant differences were observed between the respiration rates of infected and uninfected gammarids. The parasite was probably still depressing the host respiration rate at this temperature, but the oxygen uptake of G. pulex is so low that the differences between infected and uninfected individuals were too small to be detected. The parasite has a direct effect upon the physiological processes of the host, but neither the mechanism of this nor the reasons for the different effects found in different host-parasite systems are yet understood. Despite the pronounced effect of P. laevis on respiration of individual hosts, its effect upon the oxygen consumption of a natural host population is small since only a small proportion of the population carries infections and water temperatures remain below 10°C for over half the year.

Population variation in the metabolic response of deer mice to infection with Capillaria hepatica (Nematoda)

2001 ◽  
Vol 79 (4) ◽  
pp. 554-561 ◽  
Author(s):  
Shawn Meagher ◽  
Timothy P O'Connor
Keyword(s):  
Cold Stress ◽  
Metabolic Response ◽  
Host Population ◽  
Population Variation ◽  
Deer Mice ◽  
Negative Consequences ◽  
Capillaria Hepatica ◽  
Generation Times ◽  
Stress Maximum ◽  
Host Parasite

The effects of parasites on their hosts can vary among host populations, but few studies have examined geographic variation in host-parasite interactions. We examined the effects of Capillaria hepatica (Nematoda) infection on deer mice (Peromyscus maniculatus gracilis) from two different populations. Specifically, we measured the basal metabolic rate (BMR), cold-stress maximum oxygen consumption (MRpeak), metabolic scope (MRpeak/BMR), and thermogenic endurance of infected and uninfected mice from one population with, and a second population without, a history with C. hepatica. Infection had no effect on BMR, but did have effects on cold-stress measures. A previous study documented a significant relationship between survival and MRpeak in wild deer mice; hence, the effects of infection on the parameters that we measured could influence fitness. Only mice that had no historical association with C. hepatica displayed negative consequences of infection, which suggests that the historical host population has evolved mechanisms to cope with infection. Models of the evolution of virulence should include evolutionary responses of both hosts and parasites, particularly when systems involve macroparasites that have long generation times.

scholarly journals Camp stability predicts patterns of hunter–gatherer cooperation

2016 ◽  
Vol 3 (7) ◽  
pp. 160131 ◽  
Author(s):  
Daniel Smith ◽  
Mark Dyble ◽  
James Thompson ◽  
Katie Major ◽  
Abigail E. Page ◽  
...  
Keyword(s):  
Real World ◽  
Ecological Context ◽  
Hunter Gatherers ◽  
Ecological Conditions ◽  
Resource Transfers ◽  
Experimental Games ◽  
Using Data ◽  
Over Time ◽  
Do So

Humans regularly cooperate with non-kin, which has been theorized to require reciprocity between repeatedly interacting and trusting individuals. However, the role of repeated interactions has not previously been demonstrated in explaining real-world patterns of hunter–gatherer cooperation. Here we explore cooperation among the Agta, a population of Filipino hunter–gatherers, using data from both actual resource transfers and two experimental games across multiple camps. Patterns of cooperation vary greatly between camps and depend on socio-ecological context. Stable camps (with fewer changes in membership over time) were associated with greater reciprocal sharing, indicating that an increased likelihood of future interactions facilitates reciprocity. This is the first study reporting an association between reciprocal cooperation and hunter–gatherer band stability. Under conditions of low camp stability individuals still acquire resources from others, but do so via demand sharing (taking from others), rather than based on reciprocal considerations. Hunter–gatherer cooperation may either be characterized as reciprocity or demand sharing depending on socio-ecological conditions.

scholarly journals Fingerprinting Mobile Devices Using Personalized Configurations

2016 ◽  
Vol 2016 (1) ◽  
pp. 4-19 ◽  
Author(s):  
Andreas Kurtz ◽  
Hugo Gascon ◽  
Tobias Becker ◽  
Konrad Rieck ◽  
Felix Freiling
Keyword(s):  
Supervised Learning ◽  
Mobile Devices ◽  
Real World ◽  
Third Party ◽  
Learning Approach ◽  
Total Accuracy ◽  
Over Time

Abstract Recently, Apple removed access to various device hardware identifiers that were frequently misused by iOS third-party apps to track users. We are, therefore, now studying the extent to which users of smartphones can still be uniquely identified simply through their personalized device configurations. Using Apple’s iOS as an example, we show how a device fingerprint can be computed using 29 different configuration features. These features can be queried from arbitrary thirdparty apps via the official SDK. Experimental evaluations based on almost 13,000 fingerprints from approximately 8,000 different real-world devices show that (1) all fingerprints are unique and distinguishable; and (2) utilizing a supervised learning approach allows returning users or their devices to be recognized with a total accuracy of 97% over time

Trends in end-of- life (EOL) systemic oncologic treatment in contemporary clinical practice: Insights from real-world data.

2021 ◽  
Vol 39 (28_suppl) ◽  
pp. 253-253
Author(s):  
Maureen Canavan ◽  
Xiaoliang Wang ◽  
Mustafa Ascha ◽  
Rebecca A. Miksad ◽  
Timothy N Showalter ◽  
...  
Keyword(s):  
Cancer Treatment ◽  
End Of Life ◽  
Real World ◽  
Cost Of Care ◽  
Real World Data ◽  
Logistic Regression Models ◽  
Oncolytic Therapy ◽  
Immune Therapies ◽  
Using Data ◽  
Over Time

253 Background: Among patients with cancer, receipt of systemic oncolytic therapy near the end-of-life (EOL) does not improve outcomes and worsens patient and caregiver experience. Accordingly, the ASCO/NQF measure, Proportion Receiving Chemotherapy in the Last 14 Days of Life, was published in 2012. Over the last decade there has been exponential growth in high cost targeted and immune therapies which may be perceived as less toxic than traditional chemotherapy. In this study, we identified rates and types of EOL systemic therapy in today’s real-world practice; these can serve as benchmarks for cancer care organizations to drive improvement efforts. Methods: Using data from the nationwide Flatiron Health electronic health record (EHR)-derived de-identified database we included patients who died during 2015 through 2019, were diagnosed after 2011, and who had documented cancer treatment. We identified the use of aggressive EOL systemic treatment (including, chemotherapy, immunotherapy, and combinations thereof) at both 30 days and 14 days prior to death. We estimated standardized EOL rates using mixed-level logistic regression models adjusting for patient and practice-level factors. Year-specific adjusted rates were estimated in annualized stratified analysis. Results: We included 57,127 patients, 38% of whom had documentation of having received any type of systemic cancer treatment within 30 days of death (SD: 5%; range: 25% - 56%), and 17% within 14 days of death (SD: 3%; range: 10% - 30%). Chemotherapy alone was the most common EOL treatment received (18% at 30 days, 8% at 14 days), followed by immunotherapy (± other treatment) (11% at 30 days, 4% at 14 days). Overall rates of EOL treatment did not change over the study period: treatment within 30 days (39% in 2015 to 37% in 2019) and within 14 days (17% in 2015 to 17% in 2019) of death. However, the rates of chemotherapy alone within 30 days of death decreased from 24% to 14%, and within 14 days, from 10% to 6% during the study period. In comparison, rates for immunotherapy with chemotherapy (0%-6% for 30 days, 0% -2% for 14 days), and immunotherapy alone or with other treatment types (4%-13% for 30 days, 1%-4% for 14 days) increased over time for both 30 and 14 days. Conclusions: End of life systemic cancer treatment rates have not substantively changed over time despite national efforts and expert guidance. While rates of traditional chemotherapy have decreased, rates of costly immunotherapy and targeted therapy have increased, which has been associated with higher total cost of care and overall healthcare utilization. Future work should examine the drivers of end-of-life care in the era of immune-oncology.

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