Modern Mendels and Organizational Adaptation

2021 ◽  
pp. 111-126
Author(s):  
Daniel A. Levinthal
Keyword(s):  
Organizational Adaptation ◽  
Context Dependence ◽  
Controlled Trials ◽  
Recent Interest

There has been recent interest in an important mechanism of intentional, designed learning efforts: random controlled trials. We situate this mechanism within an evolutionary framework and then consider some modest propositions for our Mendelian executive. RCTs tend to suffer from a lack of consideration of context dependence, and in that regard pose an interesting contrast with processes of imitation and recombination. The Mendelian executive as envisioned here goes beyond experimentation in a narrow RCT sense and plays a broader role in nurturing organizational adaptation. Three fundamental roles of the Mendelian executive are identified: encouraging adjacencies and identifying ways in which the organization can leverage its existing strengths into new possibilities, agnostic selection reflecting the challenge of selecting out less promising pathways and amplifying more promising ones, and engaging the variegated environment in which the organization operates to both enhance the set of possible adjacencies and the diversity of feedback.

Efficacy of Vitamin D on Chronic Heart Failure Among Adults

2020 ◽  
Vol 90 (1-2) ◽  
pp. 49-58 ◽  
Author(s):  
Wang Chunbin ◽  
Wang Han ◽  
Cai Lin
Keyword(s):  
Heart Failure ◽  
Vitamin D ◽  
Chronic Heart Failure ◽  
Left Ventricular Ejection Fraction ◽  
Confidence Interval ◽  
Left Ventricular ◽  
Left Ventricular Ejection ◽  
Controlled Trials ◽  
Ventricular Ejection Fraction ◽  
Randomized Controlled

Abstract. Vitamin D deficiency commonly occurs in chronic heart failure. Whether additional vitamin D supplementation can be beneficial to adults with chronic heart failure remains unclear. We conducted a meta-analysis to derive a more precise estimation. PubMed, Embase, and Cochrane databases were searched on September 8, 2016. Seven randomized controlled trials that investigated the effects of vitamin D on cardiovascular outcomes in adults with chronic heart failure, and comprised 592 patients, were included in the analysis. Compared to placebo, vitamin D, at doses ranging from 2,000 IU/day to 50,000 IU/week, could not improve left ventricular ejection fraction (Weighted mean difference, WMD = 3.31, 95% confidence interval, CL = −0.93 to 7.55, P < 0.001, I2 = 92.1%); it also exerts no beneficial effects on the 6 minute walk distance (WMD = 18.84, 95% CL = −24.85 to 62.52, P = 0.276, I2 = 22.4%) and natriuretic peptide (Standardized mean difference, SMD = −0.39, 95% confidence interval CL = −0.48 to 0.69, P < 0.001, I2 = 92.4%). However, a dose-response analysis from two studies demonstrated an improved left ventricular ejection fraction with vitamin D at a dose of 4,000 IU/day (WMD = 6.58, 95% confidence interval CL = −4.04 to 9.13, P = 0.134, I2 = 55.4%). The results showed that high dose vitamin D treatment could potentially benefit adults with chronic heart failure, but more randomized controlled trials are required to confirm this result.

Haemostaseological complication management in caval and iliac venous stenting

VASA ◽  
2018 ◽  
Vol 47 (3) ◽  
pp. 243-246 ◽  
Author(s):  
Corinne Kohler ◽  
Torsten Fuss ◽  
Ronny Schweizer ◽  
Iris Baumgartner ◽  
Nils Kucher ◽  
...  
Keyword(s):  
Anticoagulation Therapy ◽  
Postthrombotic Syndrome ◽  
Controlled Trials ◽  
Complication Management ◽  
Endovascular Stent ◽  
Caval Vein ◽  
Clopidogrel Resistance ◽  
Venous Stenting ◽  
Randomized Controlled ◽  
Vein Occlusion

Abstract. Antiplatelet and anticoagulation therapy after venous stenting is still not standardized, data from randomized-controlled trials are missing. Rare prothrombotic disorders and nonresponsiveness to drugs must be taken into account. This case report demonstrates successful haemostaselogical complication management in recurrent rethromboses due to underlying clopidogrel resistance and low responsiveness to anticoagulation with dabigatran after endovascular stent reconstruction of chronic pelvic and caval vein occlusion in a patient with severe postthrombotic syndrome.

Intravascular ultrasound in the diagnosis and treatment of central venous diseases

VASA ◽  
2021 ◽  
Vol 50 (1) ◽  
pp. 2-10 ◽  
Author(s):  
Xin Li ◽  
Giuseppe D’Amico ◽  
Cristiano Quintini ◽  
Teresa Diago Uso ◽  
Sameer Gadani ◽  
...  
Keyword(s):  
Intravascular Ultrasound ◽  
Patient Outcomes ◽  
Controlled Trials ◽  
Ivc Filter ◽  
Venous Anatomy ◽  
Central Venous ◽  
Detailed Measurement ◽  
Filter Placement ◽  
Randomized Controlled ◽  
Venous Diseases

Summary: Intravascular ultrasound (IVUS) has been used extensively in coronary applications. Its use in venous applications has increased as endovascular therapy has increasingly become the mainstay therapy for central venous diseases. IVUS has been used for both diagnostic and therapeutic purposes in managing venous stenotic disease, venous occlusive disease, and IVC filter placement and removal. IVUS has been proven to be effective in providing detailed measurement of the venous anatomy, which aid in determining the appropriate size and the approach for venous stent placement. In IVC filter placement, IVUS can provide detailed measurement and guide IVC filter placement in emergent and critical care settings. It also has certain utility in filter removal. At any rate, to date there are only a few studies examining its impact on patient outcomes. Prospective randomized controlled trials are warranted in the future.

The Effect of Partly Missing Covariates on Statistical Power in Randomized Controlled Trials With Discrete-Time Survival Endpoints

Methodology ◽  
2017 ◽  
Vol 13 (2) ◽  
pp. 41-60
Author(s):  
Shahab Jolani ◽  
Maryam Safarkhani
Keyword(s):  
Randomized Controlled Trials ◽  
Discrete Time ◽  
Treatment Effect ◽  
Survival Data ◽  
Controlled Trials ◽  
Missing Covariates ◽  
Indicator Method ◽  
Imputation Methods ◽  
Randomized Controlled ◽  
Baseline Covariates

Abstract. In randomized controlled trials (RCTs), a common strategy to increase power to detect a treatment effect is adjustment for baseline covariates. However, adjustment with partly missing covariates, where complete cases are only used, is inefficient. We consider different alternatives in trials with discrete-time survival data, where subjects are measured in discrete-time intervals while they may experience an event at any point in time. The results of a Monte Carlo simulation study, as well as a case study of randomized trials in smokers with attention deficit hyperactivity disorder (ADHD), indicated that single and multiple imputation methods outperform the other methods and increase precision in estimating the treatment effect. Missing indicator method, which uses a dummy variable in the statistical model to indicate whether the value for that variable is missing and sets the same value to all missing values, is comparable to imputation methods. Nevertheless, the power level to detect the treatment effect based on missing indicator method is marginally lower than the imputation methods, particularly when the missingness depends on the outcome. In conclusion, it appears that imputation of partly missing (baseline) covariates should be preferred in the analysis of discrete-time survival data.

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