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1.
Alberto Marin-Sanguino Eberhard O Voit Carlos Gonzalez-Alcon Nestor V Torres 《Theoretical biology & medical modelling》2007,4(1):1-16
Background
Due to the increasing importance of identifying insulin resistance, a need exists to have a reliable mathematical model representing the glucose/insulin control system. Such a model should be simple enough to allow precise estimation of insulin sensitivity on a single patient, yet exhibit stable dynamics and reproduce accepted physiological behavior.Results
A new, discrete Single Delay Model (SDM) of the glucose/insulin system is proposed, applicable to Intra-Venous Glucose Tolerance Tests (IVGTTs) as well as to multiple injection and infusion schemes, which is fitted to both glucose and insulin observations simultaneously. The SDM is stable around baseline equilibrium values and has positive bounded solutions at all times. Applying a similar definition as for the Minimal Model (MM) SI index, insulin sensitivity is directly represented by the free parameter KxgI of the SDM. In order to assess the reliability of Insulin Sensitivity determinations, both SDM and MM have been fitted to 40 IVGTTs from healthy volunteers. Precision of all parameter estimates is better with the SDM: 40 out of 40 subjects showed identifiable (CV < 52%) KxgI from the SDM, 20 out of 40 having identifiable SI from the MM. KxgI correlates well with the inverse of the HOMA-IR index, while SI correlates only when excluding five subjects with extreme SI values. With the exception of these five subjects, the SDM and MM derived indices correlate very well (r = 0.93).Conclusion
The SDM is theoretically sound and practically robust, and can routinely be considered for the determination of insulin sensitivity from the IVGTT. Free software for estimating the SDM parameters is available. 相似文献2.
Robin J. Boyd Martin Harvey David B. Roy Tony Barber Karen A. Haysom Craig R. Macadam Roger K. A. Morris Carolyn Palmer Stephen Palmer Chris D. Preston Pam Taylor Robert Ward Stuart G. Ball Oliver L. Pescott 《Diversity & distributions》2023,29(6):774-784
Aim
To develop a causal understanding of the drivers of Species distribution model (SDM) performance.Location
United Kingdom (UK).Methods
We measured the accuracy and variance of SDMs fitted for 518 species of invertebrate and plant in the UK. Our measure of variance reflects variation among replicate model fits, and taxon experts assessed model accuracy. Using directed acyclic graphs, we developed a causal model depicting plausible effects of explanatory variables (e.g. species' prevalence, sample size) on SDM accuracy and variance and quantified those effects using a multilevel piecewise path model.Results
According to our model, sample size and niche completeness (proportion of a species' niche covered by sampling) directly affect SDM accuracy and variance. Prevalence and range completeness have indirect effects mediated by sample size. Challenging conventional wisdom, we found that the effect of prevalence on SDM accuracy is positive. This reflects the facts that sample size has a positive effect on accuracy and larger sample sizes are possible for widespread species. It is possible, however, that the omission of an unobserved confounder biased this effect. Previous studies, which reported negative correlations between prevalence and SDM accuracy, conditioned on sample size.Main conclusions
Our model explicates the causal basis of previously reported correlations between SDM performance and species/data characteristics. It also suggests that niche completeness has similarly large effects on SDM accuracy and variance as sample size. Analysts should consider niche completeness, or proxies thereof, in addition to sample size when deciding whether modelling is worthwhile. 相似文献3.
Objective
Patient involvement into medical decisions as conceived in the shared decision making method (SDM) is essential in evidence based medicine. However, it is not conclusively evident how best to define, realize and evaluate involvement to enable patients making informed choices. We aimed at investigating the ability of four measures to indicate patient involvement. While use and reporting of these instruments might imply wide overlap regarding the addressed constructs this assumption seems questionable with respect to the diversity of the perspectives from which the assessments are administered.Methods
The study investigated a nested cohort (N = 79) of a randomized trial evaluating a patient decision aid on immunotherapy for multiple sclerosis. Convergent validities were calculated between observer ratings of videotaped physician-patient consultations (OPTION) and patients'' perceptions of the communication (Shared Decision Making Questionnaire, Control Preference Scale & Decisional Conflict Scale).Results
OPTION reliability was high to excellent. Communication performance was low according to OPTION and high according to the three patient administered measures. No correlations were found between observer and patient judges, neither for means nor for single items. Patient report measures showed some moderate correlations.Conclusion
Existing SDM measures do not refer to a single construct. A gold standard is missing to decide whether any of these measures has the potential to indicate patient involvement.Practice Implications
Pronounced heterogeneity of the underpinning constructs implies difficulties regarding the interpretation of existing evidence on the efficacy of SDM. Consideration of communication theory and basic definitions of SDM would recommend an inter-subjective focus of measurement.Trial Registration
Controlled-Trials.com ISRCTN25267500. 相似文献4.
Aim
This study aimed to develop a simplified chemically defined medium that could sustain the growth and bacteriocin (enterolysin A) production by Enterococcus faecalis B9510.Methods and Results
The nutritional requirements of E. faecalis B9510 in a chemically defined medium were determined by single omission experiments. It was observed that eight amino acids (arginine, glycine, histidine, isoleucine, leucine, methionine, tryptophan and valine), three B vitamins (nicotinic acid, Ca‐pantothenic acid and pyridoxal) and magnesium sulphate were essential for growth. Based on this information, a Simplified Defined Medium (SDM) was formed consisting of 26 components. Comparison of SDM with M‐17 showed that growth and bacteriocin production in SDM was similar to that in M‐17. The bacteriocin from SDM was then purified by ultrafiltration. The retentate of ultrafiltration step was analysed by SDS‐PAGE and the results showed a single active band in the gel, which was excised and analysed by mass spectrometry, which indicated that the active band was enterolysin A, a cell wall degrading bacteriocin.Conclusions
A simplified defined medium can be formulated for the growth and bacteriocin production by Enterococcus faecalis, whose efficiency is comparable with that of a complex commercial medium.Significance and Impact of the Study
The development of such a medium can be useful for bacteriocin production and subsequent purification in a simplified manner and, therefore, helpful in the identification of novel bacteriocins. 相似文献5.
6.
Simona Panunzi Andrea De Gaetano Geltrude Mingrone 《Theoretical biology & medical modelling》2010,7(1):9
Background
The Minimal Model, (MM), used to assess insulin sensitivity (IS) from Intra-Venous Glucose-Tolerance Test (IVGTT) data, suffers from frequent lack of identifiability (parameter estimates with Coefficients of Variation (CV) less than 52%). The recently proposed Single Delay Model (SDM) is evaluated as a practical alternative. 相似文献7.
Stefanie N. Hofstede Leti van Bodegom-Vos Manon M. Wentink Carmen L. A. Vleggeert-Lankamp Thea P. M. Vliet Vlieland Perla J. Marang-van de Mheen for the DISC study group 《PloS one》2014,9(4)
Introduction
Due to the increasing specialization of medical professionals, patients are treated by multiple disciplines. To ensure that delivered care is patient-centered, it is crucial that professionals and the patient together decide on treatment (shared decision making (SDM)). However, it is not known how SDM should be integrated in multidisciplinary practice. This study determines the most important factors for SDM implementation in sciatica care, as it is known that a prior inventory of factors is crucial to develop a successful implementation strategy.Methods
246 professionals (general practitioners, physical therapists, neurologists, neurosurgeons, orthopedic surgeons) (30% response) and 155 patients (96% response) responded to an internet-based survey. Respondents ranked barriers and facilitators identified in previous interviews, on their importance using Maximum Difference Scaling. Feeding back the personal top 5 most important factors, each respondent indicated whether these factors were barriers or facilitators. Hierarchical Bayes estimation was used to estimate the relative importance (RI) of each factor.Results
Professionals assigned the highest importance to: quality of professional-patient relationship (RI 4.87; CI 4.75–4.99); importance of quick recovery of patient (RI 4.83; CI 4.69–4.97); and knowledge about treatment options (RI 6.64; CI 4.53–4.74), which were reported as barrier and facilitator. Professionals working in primary care had a different ranking than those working in hospital care. Patients assigned the highest importance to: correct diagnosis by professionals (barrier, RI 8.19; CI 7.99–8.38); information provision about treatment options and potential harm and benefits (RI 7.87; CI 7.65–8.08); and explanation of the professional about the care trajectory (RI 7.16; CI 6.94–7.38), which were reported as barrier and facilitator.Conclusions
Knowledge, information provision and a good relationship are the most important conditions for SDM perceived by both patients and professionals. These conditions are not restricted to one specific disease or health care system, because they are mostly professional or patient dependent and require healthcare professional training. 相似文献8.
Aim
Species distribution data play a pivotal role in the study of ecology, evolution, biogeography and biodiversity conservation. Although large amounts of location data are available and accessible from public databases, data quality remains problematic. Of the potential sources of error, positional errors are critical for spatial applications, particularly where these errors place observations beyond the environmental or geographical range of species. These outliers need to be identified, checked and removed to improve data quality and minimize the impact on subsequent analyses. Manually checking all species records within large multispecies datasets is prohibitively costly. This work investigates algorithms that may assist in the efficient vetting of outliers in such large datasets.Location
We used real, spatially explicit environmental data derived from the western part of Victoria, Australia, and simulated species distributions within this same region.Methods
By adapting species distribution modelling (SDM), we developed a pseudo‐SDM approach for detecting outliers in species distribution data, which was implemented with random forest (RF) and support vector machine (SVM) resulting in two new methods: RF_pdSDM and SVM_pdSDM. Using virtual species, we compared eight existing multivariate outlier detection methods with these two new methods under various conditions.Results
The two new methods based on the pseudo‐SDM approach had higher true skill statistic (TSS) values than other approaches, with TSS values always exceeding 0. More than 70% of the true outliers in datasets for species with a low and intermediate prevalence can be identified by checking 10% of the data points with the highest outlier scores.Main conclusions
Pseudo‐SDM‐based methods were more effective than other outlier detection methods. However, this outlier detection procedure can only be considered as a screening tool, and putative outliers must be examined by experts to determine whether they are actual errors or important records within an inherently biased set of data. 相似文献9.
Mireille Guerrier France Légaré Stéphane Turcotte Michel Labrecque Louis-Paul Rivest 《PloS one》2013,8(4)
Background
While shared decision making (SDM) and adherence to clinical practice guidelines (CPGs) are important, some believe they are incompatible. This study explored the mutual influence between physicians’ intention to engage in SDM and their intention to follow CPGs.Methods
Embedded within a clustered randomized trial to assess the impact of training physicians in SDM about using antibiotics to treat acute respiratory tract infections, this study evaluated physicians’ intentions to both engage in SDM and follow CPGs. A self-administered questionnaire based on the theory of planned behavior evaluated both behavioral intentions and their respective determinants (attitude, subjective norm and perceived behavioral control) at study entry and exit. We used path analysis to explore the relationships between the intentions. We conducted statistical analyses using the maximum likelihood method and the variance-covariance matrix. Goodness of fit indices encompassed the chi-square statistic, the comparative fit index and the root mean square error of approximation.Results
We analyzed 244 responses at entry and 236 at exit. In the control group, at entry we observed that physicians’ intention to engage in SDM (r = 0, t = 0.03) did not affect their intention to follow CPGs; however, their intention to follow CPGs (r = −0.31 t = −2.82) did negatively influence their intention to engage in SDM. At exit, neither behavioral intention influenced the other. In the experimental group, at entry neither behavioral intention influenced the other; at exit, the intention to engage in SDM still did not influence the intention to use CPGs, although the intention to follow CPGs (r = −0.15 t = −2.02) slightly negatively influenced the intention to engage in SDM, but this was not clinically significant.Conclusion
Physicians’ intention to engage in SDM does not affect their intention to adopt CPGs even after SDM training. Physicians’ intention to adopt CPGs had no clinically significant influence on intention to engage in SDM.Trial Registration
ClinicalTrials.gov NCT01116076相似文献10.
Background
Phenyllactic acid (PLA), a novel antimicrobial compound with broad and effective antimicrobial activity against both bacteria and fungi, can be produced by many microorganisms, especially lactic acid bacteria. However, the concentration and productivity of PLA have been low in previous studies. The enzymes responsible for conversion of phenylpyruvic acid (PPA) into PLA are equivocal.Methodology/Principal Findings
A novel thermophilic strain, Bacillus coagulans SDM, was isolated for production of PLA. When the solubility and dissolution rate of PPA were enhanced at a high temperature, whole cells of B. coagulans SDM could effectively convert PPA into PLA at a high concentration (37.3 g l−1) and high productivity (2.3 g l−1 h−1) under optimal conditions. Enzyme activity staining and kinetic studies identified NAD-dependent lactate dehydrogenases as the key enzymes that reduced PPA to PLA.Conclusions/Significance
Taking advantage of the thermophilic character of B. coagulans SDM, a high yield and productivity of PLA were obtained. The enzymes involved in PLA production were identified and characterized, which makes possible the rational design and construction of microorganisms suitable for PLA production with metabolic engineering. 相似文献11.
Assessing habitat loss and fragmentation and their effects on population viability of forest specialist birds: Linking biogeographical and population approaches
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Mario A. Carvajal Alberto J. Alaniz Cecilia Smith‐Ramírez Kathryn E. Sieving 《Diversity & distributions》2018,24(6):820-830
Aim
Biogeographic approaches usually have been developed apart from population ecology, resulting in predictive models without key parameters needed to account for reproductive and behavioural limitations on dispersal. Our aim was to incorporate fully spatially explicit population traits into a classic species distribution model (SDM) using Geographic Information Systems (GIS), aiming at conservation purposes.Location
Southern South America.Methods
Our analysis incorporates the effects of habitat loss and fragmentation on population viability and therefore provides insights into how much spatially explicit population traits can improve the SDM prediction of habitable habitat. We utilized a well‐studied focal endemic bird of South American temperate rainforests (Scelorchilus rubecula). First, at a large scale, we assessed the historical extent habitat based on climate envelopes in an SDM. Second, we used a land cover change analysis at a regional scale to account for recent habitat loss and fragmentation. Third, we used empirically derived criteria to predict population responses to fragmented forest landscapes to identify actual losses of habitat and population. Then we selected three sites of high conservation value in southern Chile and applied our population model. Finally, we discuss the degree to which spatially explicit population traits can improve the SDM output without intervening in the modelling process itself.Results
We found a historical habitat loss of 39.12% and an additional forest cover loss of 3.03% during 2000–2014; the latter occurred with a high degree of fragmentation, reducing the overall estimation of (1) carrying capacity by ?82.4%, ?33.1% and ?45.1% and (2) estimated number of pairs on viable populations by ?84.1%, ?33.0% and ?54.6% on the three selected sites.Main conclusion
We conclude that our approach sharpened the SDM prediction on environmental suitability by 54.4%, adjusting the habitable area by adding population parameters through GIS, and allowing to incorporate other phenomena as fragmentation and habitat loss.12.
Background
The wide scale permeation of health care by the shared decision making concept (SDM) reflects its relevance and advanced stage of development. An increasing number of studies evaluating the efficacy of SDM use instruments based on various sub-constructs administered from different viewpoints. However, as the concept has never been captured in operable core definition it is quite difficult to link these parts of evidence.This study aims at investigating interrelations of SDM indicators administered from different perspectives.Method
A comprehensive inventory was developed mapping judgements from different perspectives (observer, doctor, patient) and constructs (behavior, perception) referring to three units (doctor, patient, doctor-patient-dyad) and an identical set of SDM-indicators. The inventory adopted the existing approaches, but added additional observer foci (patient and doctor-patient-dyad) and relevant indicators hitherto neglected by existing instruments. The complete inventory comprising a doctor-patient-questionnaire and an observer-instrument was applied to 40 decision consultations from 10 physicians from different medical fields. Convergent validities were calculated on the basis of Pearson correlation coefficients.Results
Reliabilities for all scales were high to excellent. No correlations were found between observer and patients or physicians neither for means nor for single items. Judgements of doctors and patients were moderately related. Correlations between the observer scales and within the subjective perspectives were high. Inter-perspective agreement was not related to SDM performance or patient activity.Conclusion
The study demonstrates the contribution to involvement made by each of the relevant perspectives and emphasizes the need for an inter-subjective approach regarding SDM measurement. 相似文献13.
Background
DECISION?+?2, a training program for physicians, is designed to implement shared decision making (SDM) in the context of antibiotics use for acute respiratory tract infections (ARTIs). We evaluated the impact of DECISION?+?2 on SDM implementation as assessed by patients and physicians, and on physicians’ intention to engage in SDM.Methods
From 2010 to 2011, a multi-center, two-arm, parallel randomized clustered trial appraised the effects of DECISION?+?2 on the decision to use antibiotics for patients consulting for ARTIs. We randomized 12 family practice teaching units (FPTUs) to either DECISION?+?2 or usual care. After the consultation, both physicians and patients independently completed questionnaires based on the D-Option scale regarding SDM behaviors during the consultation. Patients also answered items assessing the role they assumed during the consultation (active/collaborative/passive). Before and after the intervention, physicians completed a questionnaire based on the Theory of Planned Behavior to measure their intention to engage in SDM. To account for the cluster design, we used generalized estimating equations and generalized linear mixed models to assess the impact of DECISION?+?2 on the outcomes of interest.Results
A total of 270 physicians (66% women) participated in the study. After DECISION?+?2, patients’ D-Option scores were 80.1?±?1.1 out of 100 in the intervention group and 74.9?±?1.1 in the control group (p?=?0.001). Physicians’ D-Option scores were 79.7?±?1.8 in the intervention group and 76.3?±?1.9 in the control group (p?=?0.2). However, subgroup analyses showed that teacher physicians D-Option scores were 79.7?±?1.5 and 73.0?±?1.4 respectively (p?=?0.001). More patients reported assuming an active or collaborative role in the intervention group (67.1%), than in the control group (49.2%) (p?=?0.04). There was a significant relation between patients’ and physicians’ D-Option scores (p?<?0.01) and also between patient-reported assumed roles and both D-Option scores (as assessed by patients, p?<?0.01; and physicians, p?=?0.01). DECISION?+?2 had no impact on the intention of physicians to engage in SDM.Conclusion
DECISION?+?2 positively influenced SDM behaviors as assessed by patients and teacher physicians. Physicians’ intention to engage in SDM was not affected by DECISION?+?2.Trial registration
ClinicalTrials.gov trials register no. NCT01116076.14.
Background
Molecular maps have been developed for many species, and are of particular importance for varietal development and comparative genomics. However, despite the existence of multiple sets of linkage maps, databases of these data are lacking for many species, including peanut. 相似文献15.
Background
Large nucleotide sequence datasets are becoming increasingly common objects of comparison. Complete bacterial genomes are reported almost everyday. This creates challenges for developing new multiple sequence alignment methods. Conventional multiple alignment methods are based on pairwise alignment and/or progressive alignment techniques. These approaches have performance problems when the number of sequences is large and when dealing with genome scale sequences. 相似文献16.
Background
Shared Decision Making (SDM) as means to the involvement of patients in medical decision making is increasingly demanded by treatment guidelines and legislation. Also, matching of patients’ preferences to treatments has been shown to be effective regarding symptom reduction. Despite promising results for patients with substance use disorders (SUD) no systematic evaluation of the literature has been provided. The aim is therefore to give a systematic overview of the literature of patient preferences and SDM in the treatment of patients with SUD.Methods
An electronic literature search of the databases Medline, Embase, Psyndex and Clinical Trials Register was performed. Variations of the search terms substance use disorders, patient preferences and SDM were used. For data synthesis the populations, interventions and outcomes were summarized and described according to the PRISMA statement. Methodological quality of the included articles was assessed with the Mixed Methods Appraisal Tool.Results
N = 25 trials were included in this review. These were conducted between 1986 and 2014 with altogether n = 8.729 patients. Two studies found that patients with SUD preferred to be actively involved in treatment decisions. Treatment preferences were assessed in n = 18 studies, where the majority of patients preferred outpatient compared with inpatient treatment. Matching patients to preferences resulted in a reduction on substance use (n = 3 studies), but the majority of studies found no significant effect. Interventions for SDM differed across patient populations and optional therapeutic techniques.Discussion
Patients with substance use disorders should be involved in medical treatment decisions, as patients with other health conditions. A suitable approach is Shared Decision Making, emphasizing the patients’ preferences. However, due to the heterogeneity of the included studies, results should be interpreted with caution. Further research is needed regarding SDM interventions in patient populations with substance use disorders. 相似文献17.
Shardul S Salunkhe Veena A Raiker Sachin Rewanwar Prakash Kotwal Avijeet Kumar Sriram Padmanabhan 《Microbial cell factories》2010,9(1):26
Background
The green fluorescent protein has revolutionized many areas of cell biology and biotechnology since it is widely used in determining gene expression and for localization of protein expression. Expression of recombinant GFP in E. coli K12 host from pBAD24M-GFP construct upon arabinose induction was significantly lower than that seen in E. coli B cells with higher expression at 30°C as compared to 37°C in E. coli K12 hosts. Since OmpT levels are higher at 37°C than at 30°C, it prompted us to modify the OmpT proteolytic sites of GFP and examine such an effect on GFP expression and fluorescence. Upon modification of one of the two putative OmpT cleavage sites of GFP, we observed several folds enhanced fluorescence of GFP as compared to unmodified GFPuv (Wild Type-WT). The western blot studies of the WT and the SDM II GFP mutant using anti-GFP antibody showed prominent degradation of GFP with negligible degradation in case of SDM II GFP mutant while no such degradation of GFP was seen for both the clones when expressed in BL21 cells. The SDM II GFP mutant also showed enhanced GFP fluorescence in other E. coli K12 OmpT hosts like E. coli JM109 and LE 392 in comparison to WT GFPuv. Inclusion of an OmpT inhibitor, like zinc with WT GFP lysate expressed from an E. coli K12 host was found to reduce degradation of GFP fluorescence by two fold. 相似文献18.
Jean-François Chenot Martin Scherer Annette Becker Norbert Donner-Banzhoff Erika Baum Corinna Leonhardt Stefan Keller Michael Pfingsten Jan Hildebrandt Heinz-Dieter Basler Michael M Kochen 《Implementation science : IS》2008,3(1):1-6
Background
There is considerable interest today in shared decision-making (SDM), defined as a decision-making process jointly shared by patients and their health care provider. However, the data show that SDM has not been broadly adopted yet. Consequently, the main goal of this proposal is to bring together the resources and the expertise needed to develop an interdisciplinary and international research team on the implementation of SDM in clinical practice using a theory-based dyadic perspective.Methods
Participants include researchers from Canada, US, UK, and Netherlands, representing medicine, nursing, psychology, community health and epidemiology. In order to develop a collaborative research network that takes advantage of the expertise of the team members, the following research activities are planned: 1) establish networking and on-going communication through internet-based forum, conference calls, and a bi-weekly e-bulletin; 2) hold a two-day workshop with two key experts (one in theoretical underpinnings of behavioral change, and a second in dyadic data analysis), and invite all investigators to present their views on the challenges related to the implementation of SDM in clinical practices; 3) conduct a secondary analyses of existing dyadic datasets to ensure that discussion among team members is grounded in empirical data; 4) build capacity with involvement of graduate students in the workshop and online forum; and 5) elaborate a position paper and an international multi-site study protocol.Discussion
This study protocol aims to inform researchers, educators, and clinicians interested in improving their understanding of effective strategies to implement shared decision-making in clinical practice using a theory-based dyadic perspective. 相似文献19.
Background
Many common disorders have multiple genetic components which convey increased susceptibility. SNPs have been used to identify genetic components which are associated with a disease. Unfortunately, many studies using these methods suffer from low reproducibility due to lack of power. 相似文献20.
In search of relevant predictors for marine species distribution modelling using the MarineSPEED benchmark dataset
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Samuel Bosch Lennert Tyberghein Klaas Deneudt Francisco Hernandez Olivier De Clerck 《Diversity & distributions》2018,24(2):144-157