Stu2p is a member of a conserved family of microtubule-binding proteins and an essential protein in yeast. Here, we report the first in vivo analysis of microtubule dynamics in cells lacking a member ...of this protein family. For these studies, we have used a conditional Stu2p depletion strain expressing alpha-tubulin fused to green fluorescent protein. Depletion of Stu2p leads to fewer and less dynamic cytoplasmic microtubules in both G1 and preanaphase cells. The reduction in cytoplasmic microtubule dynamics is due primarily to decreases in both the catastrophe and rescue frequencies and an increase in the fraction of time microtubules spend pausing. These changes have significant consequences for the cell because they impede the ability of cytoplasmic microtubules to orient the spindle. In addition, recovery of fluorescence after photobleaching indicates that kinetochore microtubules are no longer dynamic in the absence of Stu2p. This deficiency is correlated with a failure to properly align chromosomes at metaphase. Overall, we provide evidence that Stu2p promotes the dynamics of microtubule plus-ends in vivo and that these dynamics are critical for microtubule interactions with kinetochores and cortical sites in the cytoplasm.
Abstract Background The current number of physicians will not be sufficient to accommodate 30 to 40 million Americans expected to secure health coverage with Affordable Care Act implementation. One ...proposed solution is to use advanced practice providers (APPs) (nurse practitioners and physician assistants). Objectives This study sought to determine whether there were clinically meaningful differences in the quality of care delivered by APPs versus physicians in a national sample of cardiology practices. Methods Within the American College of Cardiology’s PINNACLE Registry, we compared quality of coronary artery disease (CAD), heart failure, and atrial fibrillation care delivered by physicians and APPs for outpatient visits between January 1, 2012, and December 31, 2012. We performed hierarchical regression adjusting for provider sex; panel size; duration of participation in registry; and patient’s age, sex, insurance, number of outpatient visits, history of hypertension, diabetes, myocardial infarction, and percutaneous coronary intervention or coronary artery bypass grafting in the preceding 12 months. Results We included 883 providers (716 physicians and 167 APPs) in 41 practices who cared for 459,669 patients. Mean number of patients seen by APPs (260.7) was lower compared with that seen by physicians (581.2). Compliance with most CAD, heart failure, and atrial fibrillation measures was comparable, except for a higher rate of smoking cessation screening and intervention (adjusted rate ratio: 1.14; 95% confidence interval: 1.03 to 1.26) and cardiac rehabilitation referral (rate ratio: 1.40; 95% confidence interval: 1.16 to 1.70) among CAD patients receiving care from APPs. Compliance with all eligible CAD measures was low for both (12.1% and 12.2% for APPs and physicians, respectively) with no significant difference. Results were consistent when comparing practices with both physicians and APPs (n = 41) and physician-only practices (n = 49). Conclusions Apart from minor differences, a collaborative care delivery model, using both physicians and APPs, may deliver an overall comparable quality of outpatient cardiovascular care compared with a physician-only model.
Imaging the mitotic spindle Maddox, Paul S; Ladouceur, Anne-Marie; Ranjan, Rajesh ...
Methods in enzymology,
2012, Letnik:
505
Journal Article
Recenzirano
The mitotic spindle, due to its striking form, has been imaged for well over 100 years. Composed largely of microtubules and chromosomes, the spindle also contains numerous proteins whose roles ...include biochemical and biophysical regulation of mitosis. Given the transient, dynamic nature of the spindle, the light microscope continues to be the main tool employed to unlock its mysteries. In this chapter, we will discuss modern light microscopy techniques commonly used for imaging this intricate cellular machine as well as provide examples and protocols. We will also describe some biological preparations and experimental regimes for investigation of the mitotic spindle.
Abstract Background In a significant update, the 2013 American College of Cardiology/American Heart Association (ACC/AHA) cholesterol guidelines recommend fixed-dose statin therapy for those at risk ...and do not recommend nonstatin therapies or treatment to target low-density lipoprotein cholesterol (LDL-C) levels, limiting the need for repeated LDL-C testing. Objectives The goal of this study was to examine the impact of the 2013 ACC/AHA cholesterol guidelines on current U.S. cardiovascular practice. Methods Using the NCDR PINNACLE (National Cardiovascular Data Registry Practice Innovation and Clinical Excellence) registry data from 2008 to 2012, we assessed current practice patterns as a function of the 2013 cholesterol guidelines. Lipid-lowering therapies and LDL-C testing patterns by patient risk group (atherosclerotic cardiovascular disease ASCVD, diabetes, LDL-C ≥190 mg/dl, or an estimated 10-year ASCVD risk ≥7.5%) were described. Results Among a cohort of 1,174,545 patients, 1,129,205 (96.1%) were statin-eligible (91.2% ASCVD, 6.6% diabetes, 0.3% off-treatment LDL-C ≥190 mg/dl, 1.9% estimated 10-year ASCVD risk ≥7.5%). There were 377,311 patients (32.4%) not receiving statin therapy and 259,143 (22.6%) receiving nonstatin therapies. During the study period, 20.8% of patients had 2 or more LDL-C assessments, and 7.0% had more than 4. Conclusions In U.S. cardiovascular practices, 32.4% of statin-eligible patients, as defined by the 2013 ACC/AHA cholesterol guidelines, were not currently receiving statins. In addition, 22.6% were receiving nonstatin lipid-lowering therapies and 20.8% had repeated LDL-C testing. Achieving concordance with the new cholesterol guidelines in patients treated in U.S. cardiovascular practices would result in significant increases in statin use, as well as significant reductions in nonstatin therapies and laboratory testing.
The Centromere is a unique chromosomal locus where the kinetochore is formed to mediate faithful chromosome partitioning, thus maintaining ploidy during cell division. Centromere identity is ...inherited via an epigenetic mechanism involving a histone H3 variant, called centromere protein A (CENP-A) which replaces H3 in centromeric chromatin. In spite of extensive efforts in field of centromere biology during the past decade, controversy persists over the structural nature of the CENP-A-containing epigenetic mark, both at nucleosomal and chromatin levels. Here, we review recent findings and hypotheses regarding the structure of CENP-A-containing complexes.
The objective of this study is to examine practice-level variation in rates of guideline-recommended treatment for outpatients with heart failure and reduced ejection fraction, and to examine the ...association between treatment variation and practice site, independent of patient factors.
Cardiology practices participating in the National Cardiovascular Disease Registry Practice Innovation and Clinical Excellence registry from July 2008 to December 2010 were evaluated. Practice rates of treatment with angiotensin-converting enzyme inhibitors/angiotensin receptor blockers and β-blockers and an optimal combined treatment measure were determined for patients with heart failure and reduced ejection fraction and no documented contraindications. Multivariable hierarchical regression models were adjusted for demographics, insurance status, and comorbidities. A median rate ratio was calculated for each therapy, which describes the likelihood that the treatment of a patient with given comorbidities would differ at 2 randomly selected practices. We identified 12 556 patients from 45 practices. The unadjusted practice-level prescription rates ranged from 44% to 100% for angiotensin-converting enzyme inhibitors/angiotensin receptor blockers (median, 85%; interquartile range, 75%-89%), from 49% to 100% for β-blockers (median, 92%; interquartile range, 83%-95%), and from 37% to 100% for optimal combined treatment (median, 79%; interquartile range, 66%-85%). The adjusted median rate ratio was 1.11 (95% confidence interval, 1.08-1.18) for angiotensin-converting enzyme inhibitors/angiotensin receptor blockers therapy, 1.08 (95% confidence interval, 1.05-1.15) for β-blockers therapy, and 1.17 (1.13-1.26) for optimal combined treatment.
Variation in the use of guideline-recommended medications for patients with heart failure and reduced ejection fraction exists in the outpatient setting. Addressing practice-level differences may be an important component of improving quality of care for patients with heart failure and reduced ejection fraction.
There is a reported association between high clinical volume and improved outcomes. Whether this relationship is true for outpatients with coronary artery disease (CAD), heart failure (HF), and ...atrial fibrillation (AF) remains unknown.
Using the PINNACLE Registry (2009-2012), average monthly provider and practice volumes were calculated for CAD, HF, and AF. Adherence with 4 American Heart Association CAD, 2 HF, and 1 AF performance measure were assessed at the most recent encounter for each patient. Hierarchical logistic regression models were used to assess the relationship between provider and practice volume and performance on eligible quality measures. Data incorporated patients from 1094 providers at 71 practices (practice level analyses n=654 535; provider level analyses n=529 938). Median monthly provider volumes were 79 (interquartile range IQR, 51-117) for CAD, 27 (16-45) for HF, and 37 (24-54) for AF. Median monthly practice volumes were 923 (IQR, 476-1455) for CAD, 311 (145-657) for HF, and 459 (185-720) for AF. Overall, 55% of patients met all CAD measures, 72% met all HF measures, and 58% met the AF measure. There was no definite relationship between practice volume and concordance for CAD, AF, or HF (P=0.56, 0.52, and 0.79, respectively). In contrast, higher provider volume was associated with increased concordance for CAD and AF performance measures (P<0.001 for both), but not for HF (P=0.36).
In the PINNACLE registry, performance was modest and variable. Higher provider volume was positively associated with quality, whereas practice volume was not.
It has been hypothesized that spatial gradients in kMT dynamic instability facilitate mitotic spindle formation and chromosome movement. To test this hypothesis requires the analysis of kMT dynamics, ...which have not been resolved at the single kMT level in living cells. The budding yeast spindle offers an attractive system in which to study kMT dynamics because, in contrast to animal cells, there is only one kMT per kinetochore. To visualize metaphase kMT plus-end dynamics in yeast, a strain containing a green fluorescent protein fusion to the kinetochore protein, Cse4, was imaged by fluorescence microscopy. Although individual kinetochores were not resolvable, we found that models of kMT dynamics could be evaluated by simulating the stochastic kMT dynamics and then simulating the fluorescence imaging of kMT plus-end-associated kinetochores. Statistical comparison of model-predicted images to experimentally observed images demonstrated that a pure dynamic instability model for kMT dynamics in the yeast metaphase spindle was unacceptable. However, when a temporally stable spatial gradient in the catastrophe or rescue frequency was added to the model, there was reasonable agreement between the model and the experiment. These results provide the first evidence of temporally stable spatial gradients of kMT catastrophe and/or rescue frequency in living cells.
Variation in the activity of the spindle assembly checkpoint has been observed in different cell types, yet the reason for this variability remains poorly understood. Reporting in Developmental Cell, ...Galli and Morgan (2016) show that checkpoint activity increases during development as cell size, and the cytoplasm-to-kinetochore ratio, decreases.
Variation in the activity of the spindle assembly checkpoint has been observed in different cell types, yet the reason for this variability remains poorly understood. Reporting in Developmental Cell, Galli and Morgan (2016) show that checkpoint activity increases during development as cell size, and the cytoplasm-to-kinetochore ratio, decreases.
Objectives This study assessed practice variations in secondary prevention medication prescriptions among coronary artery disease (CAD) patients treated in outpatient practices participating in the ...National Cardiovascular Data Registry (NCDR) Practice Innovation and Clinical Excellence (PINNACLE) registry. Background Among patients with CAD, secondary prevention with a combination of beta-blockers, angiotensin-converting enzyme inhibitors/angiotensin receptor blockers, and statins reduces cardiac mortality and myocardial infarction (MI). Accordingly, every CAD patient should receive the combination of these medications for which they are eligible. However, little is known about current prescription patterns of these medications and the variation in use among outpatient cardiology clinics. Methods Using data from NCDR PINNACLE registry, a national outpatient cardiology practice registry, we assessed medication prescription patterns among eligible CAD patients, between July 2008 and December 2010. Overall rates of prescription and variation by practice were calculated, adjusting for patient characteristics. Results Among 156,145 CAD patients in 58 practices, 103,830 (66.5%) patients were prescribed the optimal combination of medications for which they were eligible. The median rate of optimal combined prescription by practice was 73.5% and varied from 28.8% to 100%. After adjustment for patient factors, the practice median rate ratio for prescription was 1.25 (95% confidence interval: 1.20 to 1.32), indicating a 25% likelihood that 2 random practices would differ in treating identical CAD patients. Conclusions Among a national registry of CAD patients treated in outpatient cardiology practices, over one-third of patients failed to receive their optimal combination of secondary prevention medications. Significant variation was observed across practices, even after adjusting for patient characteristics, suggesting that quality improvement efforts may be needed to support more uniform practice.
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