47 research outputs found
The preparation of porcine (Tyr-A14-2H) insulin and its characterization by mass spectrometry
The title compound was prepared by catalytic deiodination of (Tyr-A14-3-I) insulin with deuterium gas. Under special conditions (large excess of PdO in CH3OD/D2O at pH 9.2) developed to minimize problems due to poisoning of the catalyst, deuterated insulin was produced in yields of about 35% after purification by reversed phase HPLC. For analysis, the deuterated insulin was digested with V8 protease and was shown by mass spectrometry to have incorporated deuterium to an extent of 96.6 atom %, exclusively in a pentapeptide containing Tyr A14. The title compound should prove useful to those workers studying insulin by mass spectrometry, and use of the method with tritium gas in place of deuterium should permit the preparation of a specifically labelled radioactive insulin analogue which behaves identically to the natural hormon
Rapid Independent Trait Evolution despite a Strong Pleiotropic Genetic Correlation
This is the publisher's version. It can also be found here:http://dx.doi.org/10.1086/661907Genetic correlations are the most commonly studied of all potential constraints on adaptive evolution. We present a comprehensive test of constraints caused by genetic correlation, comparing empirical results to predictions from theory. The additive genetic correlation between the filament and the corolla tube in wild radish flowers is very high in magnitude, is estimated with good precision, and is caused by pleiotropy. Thus, evolutionary changes in the relative lengths of these two traits should be constrained. Still, artificial selection produced rapid evolution of these traits in opposite directions, so that in one replicate relative to controls, the difference between them increased by six standard deviations in only nine generations. This would result in a 54% increase in relative fitness on the basis of a previous estimate of natural selection in this population, and it would produce the phenotypes found in the most extreme species in the family Brassicaceae in less than 100 generations. These responses were within theoretical expectations and were much slower than if the genetic correlation was zero; thus, there was evidence for constraint. These results, coupled with comparable results from other species, show that evolution can be rapid despite the constraints caused by genetic correlations
A look back to move ahead: New directions for research on proactive performance and other discretionary work behaviours
Over the last two decades, the multi-dimensional notion of job performance has been fully brought to life. The differentiation between core task performance and various aspects of discretionary work behaviour is now commonly applied. A multitude of empirical studies, enhancing our knowledge of the antecedents and consequences of the different performance aspects, have recently been summarised through various meta-analyses. We use this as an occasion for taking stock in order to identify new areas of theorising and empirical research. Focusing in particular on proactive performance aspects, the present paper identifies three themes that could inspire new research and model development. We suggest taking a new approach to the treatment of time in order to account for the dynamic nature of performance on the one hand, and to consider life-span changes on the other, developing comprehensive models on proactivity-enhancing interventions, and more strongly incorporating a cross- cultural perspective
The development and validation of a scoring tool to predict the operative duration of elective laparoscopic cholecystectomy
Background: The ability to accurately predict operative duration has the potential to optimise theatre efficiency and utilisation, thus reducing costs and increasing staff and patient satisfaction. With laparoscopic cholecystectomy being one of the most commonly performed procedures worldwide, a tool to predict operative duration could be extremely beneficial to healthcare organisations.
Methods: Data collected from the CholeS study on patients undergoing cholecystectomy in UK and Irish hospitals between 04/2014 and 05/2014 were used to study operative duration. A multivariable binary logistic regression model was produced in order to identify significant independent predictors of long (> 90 min) operations. The resulting model was converted to a risk score, which was subsequently validated on second cohort of patients using ROC curves.
Results: After exclusions, data were available for 7227 patients in the derivation (CholeS) cohort. The median operative duration was 60 min (interquartile range 45–85), with 17.7% of operations lasting longer than 90 min. Ten factors were found to be significant independent predictors of operative durations > 90 min, including ASA, age, previous surgical admissions, BMI, gallbladder wall thickness and CBD diameter. A risk score was then produced from these factors, and applied to a cohort of 2405 patients from a tertiary centre for external validation. This returned an area under the ROC curve of 0.708 (SE = 0.013, p 90 min increasing more than eightfold from 5.1 to 41.8% in the extremes of the score.
Conclusion: The scoring tool produced in this study was found to be significantly predictive of long operative durations on validation in an external cohort. As such, the tool may have the potential to enable organisations to better organise theatre lists and deliver greater efficiencies in care
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Long-term grazing effects on genetic variation in Idaho fescue
The effect of cattle grazing on the genetic structure of native grass populations has received little attention. We investigated the effect of cattle grazing on genetic variation in Idaho fescue (Festuca idahoensis Elmer) using ISSR (inter-simple sequence repeat) DNA markers. The ISSR markers are hypervariable and are generally interpreted as being selectively neutral. Idaho fescue tillers were sampled from inside (N = 31) and outside (N = 34) a 64-year-old cattle exclosure in southeastern Oregon. We extracted DNA and used 2 ISSR primers to determine the genotypes for grazed and ungrazed plants at 60 variable loci. No statistically significant differences were observed between grazed and ungrazed samples for percent polymorphic loci (grazed = 85%; ungrazed = 80%), mean expected heterozygosity (grazed = 0.1393; ungrazed = 0.1365), or for a measure of loci dissimilarity (grazed = 0.506; ungrazed = 0.536). We also found that the ungrazed individuals sampled inside the exclosure were not significantly genetically differentiated from the grazed individuals sampled outside the exclosure (Gst = 0.0008 averaged across all loci). Our results differ from past studies that found demographic and physiological differences between Idaho fescue inside and outside of grazing exclosures at the same site. Our results mirror those of other researchers who have also failed to detect genetic differences at marker loci in response to grazing. We propose that either the mechanisms that must be present to cause changes in neutral genetic variation are not affected by cattle grazing for Idaho fescue at this site, or that any effects of grazing on neutral genetic variation were overwhelmed by gene flow between the grazed and ungrazed samples.The Journal of Range Management archives are made available by the Society for Range Management and the University of Arizona Libraries. Contact [email protected] for further information.Migrated from OJS platform August 202
2001FieldFlowerMeas
Floral traits measured repeatedly across the life of the plant