Predictors of adherence to prescribed exercise programs for older adults with medical or surgical indications for exercise: a systematic review.

BACKGROUND AND OBJECTIVES: Prescribed exercise to treat medical conditions and to prepare for surgery is a promising intervention to prevent adverse health outcomes for older adults; however, adherence to exercise programs may be low. Our objective was to identify and grade the quality of predictors of adherence to prescribed exercise in older adults. METHODS: Prospective observational and experimental studies were identified using a peer-reviewed search strategy applied to MEDLINE, EMBASE, Cochrane, and CINAHL from inception until October 6, 2020. Following an independent and duplicate review of titles, abstracts, and full texts, we included prospective studies with an average population age >65 years, where exercise was formally prescribed for a medical or surgical condition. We excluded studies where exercise was prescribed for a chronic musculoskeletal condition. Risk of bias was assessed using the Quality in Prognostic studies tool or Cochrane risk of bias tool, as appropriate. Predictors of adherence were identified and graded for quality using an adaptation of the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) framework for predictor studies. RESULTS: We included 19 observational studies and 4 randomized controlled trials (n=5785) Indications for exercise included cardiac (n=6), pulmonary rehabilitation (n=7), or other (n=10; surgical, medical, and neurologic). Of the 10 studies that reported adherence as the percent of prescribed sessions completed, average adherence was 80% (range 60-98%; standard deviation (SD) 11%). Of the 10 studies that reported adherence as a categorical threshold demarking adherent vs not adherent, average adherence was 57.5% (range 21-83%; SD 21%). Moderate-quality evidence suggested that positive predictors of adherence were self-efficacy and good self-rated mental health; negative predictors were depression (high quality) and distance from the exercise facility. Moderate-quality evidence suggested that comorbidity and age were not predictive of adherence. CONCLUSIONS: These findings can inform the design of future exercise programs as well as the identification of individuals who may require extra support to benefit from prescribed exercise. SYSTEMATIC REVIEW REGISTRATION: PROSPERO CRD42018108242.

Use of Statins to Augment Progenitor Cell Function in Preclinical and Clinical Studies of Regenerative Therapy: a Systematic Review.

BACKGROUND: Mesenchymal stromal cells (MSCs) and endothelial progenitor cells (EPCs) are used in cell-based regenerative therapy. HMG CoA reductase inhibitors (statins) appear promising in blocking apoptosis, prolonging progenitor cell survival and improving their capacity to repair organ function. METHODS: We performed a systematic review of preclinical and clinical studies to clarify whether statins can improve cell-based repair of organ injury. MEDLINE, EMBASE, and PUBMED databases were searched (1947 to June 25, 2013). Controlled clinical and pre-clinical studies were included that evaluated statin therapy used alone or in combination with MSCs or EPCs in patients or animals with organ injury. RESULTS: After screening 771 citations, 100 records underwent full eligibility screening of which 38 studies met eligibility and were included in the review: Studies were grouped into pre-clinical studies that involved statin treatment in combination with cell therapy (18 studies), preclinical studies of statin therapy alone (13 studies) and clinical studies of statin therapy (7 studies). Studies addressed cardiac injury (14 studies), vascular disorders (15 studies), neurologic conditions (8 studies) and bone fractures (1 study). Pre-clinical studies of statins in combination with MSC infusion (15 studies) or EPC therapy (3 studies) were described and despite marked heterogeneity in reporting outcomes of cellular analysis and organ function, all of these cell-based pre-clinical studies reported improved organ recovery with the addition of statin therapy. Moreover, 13 pre-clinical studies involved the administration of a statin drug alone to animals. An increase in EPC number and/or function (no studies of MSCs) was reported in 11 of these studies (85 %) and improved organ function in 12 studies (92 %). We also identified 7 clinical studies and none involved the administration of cells but described an increased number and/or function of EPCs (no studies of MSCs) and improved organ function with statin therapy (1.2-fold to 35-fold improvement over controls) in all 7 studies. CONCLUSION: Our systematic review provides a foundation of encouraging results that support further study of statins in regenerative therapy to augment the number and/or function of MSCs used in cell-based repair and to augment the number and function of EPCs in vivo to repair damaged tissues. Larger studies are needed to ensure safety and confirm clinical benefits.

Redundant Regulation of Cdk1 Tyrosine Dephosphorylation in Saccharomyces cerevisiae.

Cdk1 activity drives both mitotic entry and the metaphase-to-anaphase transition in all eukaryotes. The kinase Wee1 and the phosphatase Cdc25 regulate the mitotic activity of Cdk1 by the reversible phosphorylation of a conserved tyrosine residue. Mutation of cdc25 in Schizosaccharomyces pombe blocks Cdk1 dephosphorylation and causes cell cycle arrest. In contrast, deletion of MIH1, the cdc25 homolog in Saccharomyces cerevisiae, is viable. Although Cdk1-Y19 phosphorylation is elevated during mitosis in mih1∆ cells, Cdk1 is dephosphorylated as cells progress into G1, suggesting that additional phosphatases regulate Cdk1 dephosphorylation. Here we show that the phosphatase Ptp1 also regulates Cdk1 dephosphorylation in vivo and can directly dephosphorylate Cdk1 in vitro. Using a novel in vivo phosphatase assay, we also show that PP2A bound to Rts1, the budding yeast B56-regulatory subunit, regulates dephosphorylation of Cdk1 independently of a function regulating Swe1, Mih1, or Ptp1, suggesting that PP2A(Rts1) either directly dephosphorylates Cdk1-Y19 or regulates an unidentified phosphatase.

Competition between Heterochromatic Loci Allows the Abundance of the Silencing Protein, Sir4, to Regulate de novo Assembly of Heterochromatin.

Changes in the locations and boundaries of heterochromatin are critical during development, and de novo assembly of silent chromatin in budding yeast is a well-studied model for how new sites of heterochromatin assemble. De novo assembly cannot occur in the G1 phase of the cell cycle and one to two divisions are needed for complete silent chromatin assembly and transcriptional repression. Mutation of DOT1, the histone H3 lysine 79 (K79) methyltransferase, and SET1, the histone H3 lysine 4 (K4) methyltransferase, speed de novo assembly. These observations have led to the model that regulated demethylation of histones may be a mechanism for how cells control the establishment of heterochromatin. We find that the abundance of Sir4, a protein required for the assembly of silent chromatin, decreases dramatically during a G1 arrest and therefore tested if changing the levels of Sir4 would also alter the speed of de novo establishment. Halving the level of Sir4 slows heterochromatin establishment, while increasing Sir4 speeds establishment. yku70Δ and ubp10Δ cells also speed de novo assembly, and like dot1Δ cells have defects in subtelomeric silencing, suggesting that these mutants may indirectly speed de novo establishment by liberating Sir4 from telomeres. Deleting RIF1 and RIF2, which suppresses the subtelomeric silencing defects in these mutants, rescues the advanced de novo establishment in yku70Δ and ubp10Δ cells, but not in dot1Δ cells, suggesting that YKU70 and UBP10 regulate Sir4 availability by modulating subtelomeric silencing, while DOT1 functions directly to regulate establishment. Our data support a model whereby the demethylation of histone H3 K79 and changes in Sir4 abundance and availability define two rate-limiting steps that regulate de novo assembly of heterochromatin.

Current trends in clinical studies of allogeneic hematopoietic stem cell transplantation.

Allogeneic hematopoietic stem cell transplantation (HSCT) is a specialized intervention performed at select centers worldwide. The extent to which specific aspects of care in allogeneic HSCT have been studied and the types of studies performed for different aspects of care remains incompletely documented. Studies in allogeneic HSCT were systematically identified from selected high-profile transplant journals between July 2010 and June 2011 and previously reported in a study addressing the definition of clinical outcomes in HSCT. All articles were retrieved and assessed for study characteristics and categorized by specific aspects of care related to allogeneic HSCT. One hundred sixteen articles were retrieved and reviewed in detail by 2 investigators. The most studied aspect of care was conditioning regimens. Transfusion practices were the most understudied aspect of care. Interestingly, most studies included both adult and pediatric patients. Studies involving all hematological malignancies were encountered more often than disease-specific studies. Geographically, most patients described in the published reports were treated only in North America or only in Europe. Most studies were retrospective (78), and 25 reported on multicenter registry data. Of the 38 prospective studies, 8 were randomized controlled trials (RCTs) and predominantly focused on prevention and treatment of graft-versus-host disease (GVHD) and infections. Median follow-up was longer in retrospective registry studies (54 months) and shortest in RCTs (32 months). The proportion of positive outcomes in retrospective and prospective studies was remarkably high (>80% for all categories) and not significantly different across all aspects of care (P > .05). When comparing RCTs and registry data studies, this proportion was similar and high (95% and 100%, respectively, P > .05). Our study highlights the established and important role of retrospective registry studies for many aspects of care and suggests RCTs may be most relevant for studies on infectious complications and GVHD.

A Wee1 checkpoint inhibits anaphase onset.

Cdk1 drives both mitotic entry and the metaphase-to-anaphase transition. Past work has shown that Wee1 inhibition of Cdk1 blocks mitotic entry. Here we show that the budding yeast Wee1 kinase, Swe1, also restrains the metaphase-to-anaphase transition by preventing Cdk1 phosphorylation and activation of the mitotic form of the anaphase-promoting complex/cyclosome (APC(Cdc20)). Deletion of SWE1 or its opposing phosphatase MIH1 (the budding yeast cdc25(+)) altered the timing of anaphase onset, and activation of the Swe1-dependent morphogenesis checkpoint or overexpression of Swe1 blocked cells in metaphase with reduced APC activity in vivo and in vitro. The morphogenesis checkpoint also depended on Cdc55, a regulatory subunit of protein phosphatase 2A (PP2A). cdc55Δ checkpoint defects were rescued by mutating 12 Cdk1 phosphorylation sites on the APC, demonstrating that the APC is a target of this checkpoint. These data suggest a model in which stepwise activation of Cdk1 and inhibition of PP2A(Cdc55) triggers anaphase onset.