Publications by authors named "Charlotte Collins"

28 Publications

  • Page 1 of 1

Telehealth versus self-directed lifestyle intervention to promote healthy blood pressure: a protocol for a randomised controlled trial.

BMJ Open 2021 Mar 3;11(3):e044292. Epub 2021 Mar 3.

Kidney Health Research Institute, Geisinger, Danville, Pennsylvania, USA

Introduction: Weight loss, consumption of a Dietary Approaches to Stop Hypertension dietary pattern, reduced sodium intake and increased physical activity have been shown to lower blood pressure (BP). Use of web-based tools and telehealth to deliver lifestyle counselling could be potentially scalable solutions to improve BP through behavioural modification though limited data exists to support these approaches in clinical practice.

Methods And Analysis: This randomised controlled trial will compare the efficacy of a telehealth versus self-directed lifestyle intervention in lowering 24-hour SBP in patients with overweight/obesity (body mass index ≥25 kg/m) and 24-hour SBP 120-160 mm Hg. All participants receive personalised recommendations to improve dietary quality based on a web-based Food Frequency Questionnaire, access to an online comprehensive weight management programme and a smartphone dietary app. The telehealth arm additionally includes weekly calls with registered dietitian nutritionists who use motivational interviewing. The primary outcome is change from baseline to 12 weeks in 24-hour SBP. Secondary outcomes include changes from baseline in 24-hour diastolic BP, daytime SBP, nighttime SP, daytime diastolic BP, nighttime diastolic BP, total Healthy Eating Index-2015 score, weight, waist circumference and physical activity. Other prespecified outcomes will include change in individual components of the Healthy Eating Index-2015 score, and satisfaction with the Healthy BP research study measured on a 5-point Likert scale.

Ethics And Dissemination: The study has been approved by the Geisinger Institutional Review Board. Results will be disseminated through peer-reviewed publications and conference presentations.

Trial Registration Number: NCT03700710.
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http://dx.doi.org/10.1136/bmjopen-2020-044292DOI Listing
March 2021

A Program to Provide Clinicians with Feedback on Their Diagnostic Performance in a Learning Health System.

Jt Comm J Qual Patient Saf 2021 Feb 29;47(2):120-126. Epub 2020 Aug 29.

Problem: Reducing diagnostic errors requires improving both systems and individual clinical reasoning. One strategy to achieve diagnostic excellence is learning from feedback. However, clinicians remain uncomfortable receiving feedback on their diagnostic performance. Thus, a team of researchers and clinical leaders aimed to develop and implement a diagnostic performance feedback program for learning that mitigates potential clinician discomfort.

Approach: The program was developed as part of a larger project to create a learning health system around diagnostic safety at Geisinger, a large, integrated health care system in rural Pennsylvania. Steps included identifying potential missed opportunities in diagnosis (MODs) from various sources (for example, risk management, clinician reports, patient complaints); confirming MODs through chart review; and having trained facilitators provide feedback to clinicians about MODs as learning opportunities. The team developed a guide for facilitators to conduct effective diagnostic feedback sessions and surveyed facilitators and recipients about their experiences and perceptions of the feedback sessions.

Outcomes: 28 feedback sessions occurred from January 2019 to June 2020, involving MODs from emergency medicine, primary care, and hospital medicine. Most facilitators (90.6% [29/32]) reported that recipients were receptive to learning and discussing MODs. Most recipients reported that conversations were constructive and nonpunitive (83.3% [25/30]) and allowed them to take concrete steps toward improving diagnosis (76.7% [23/30]). Both groups believed discussions would improve future diagnostic safety (93.8% [30/32] and 70.0% [21/30], respectively).

Key Insights And Next Steps: An institutional program was developed and implemented to deliver diagnostic performance feedback. Such a program may facilitate learning and improvement to reduce MODs. Future efforts should assess long-term effects on diagnostic performance and patient outcomes.
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http://dx.doi.org/10.1016/j.jcjq.2020.08.014DOI Listing
February 2021

Remote Dietary Counseling Using Smartphone Applications in Patients With Stages 1-3a Chronic Kidney Disease: A Mixed Methods Feasibility Study.

J Ren Nutr 2020 01 8;30(1):53-60. Epub 2019 May 8.

Department of Family Medicine and Public Health, Division of Preventive Medicine, University of California San Diego, San Diego, CA.

Objective(s): Although healthy dietary patterns are associated with decreased mortality in patients with chronic kidney disease (CKD), few patients receive dietitian counseling due to concerns such as dietitian availability, travel distance, and cost. Our objective was to determine the feasibility of dietary smartphone application-supported telecounseling to reduce sodium intake and improve dietary quality in patients with early CKD.

Methods: This was a pre-post, mixed methods feasibility study of 16 patients with Stage 1-3a CKD in central/northeast Pennsylvania. Patients recorded and shared dietary data via smartphone applications with registered dietitians, who used motivational interviewing to provide telephone counseling weekly for 8 weeks. Seven patients were assigned to a customized study-specific application and nine patients to a commercially available, free application (MyFitnessPal). Participant satisfaction was assessed via survey, and participants were invited to complete a semistructured interview. Outcomes assessed included sodium intake, Healthy Eating Index 2015 score, weight, and 24-hour blood pressure (BP).

Results: Mean age was 64.7 years, 31% were female, 100% were white, 13% had income <$25,000. Adherence was excellent with 14 (88%) entering dietary data at least 75% of total days. Patients reported high satisfaction with the intervention and dietitian telecounseling. Use of dietary apps was viewed positively for allowing tracking of sodium and energy intake although some participants experienced functionality issues with the customized application that were not generally experienced by those using the commercially available free application. Sodium intake (-604 mg/day, 95% confidence interval [CI]: -1,104 to -104), Healthy Eating Index 2015 score (3.97, 95% CI: 0.03-7.91), weight (-3.4, 95% CI: -6.6 to -0.1), daytime systolic BP (-5.8, 95% CI: -12.1 to 0.6), and daytime diastolic BP (-4.1, 95% CI: -7.9 to -0.2) improved after the intervention.

Conclusions: An application-supported telecounseling program with a registered dietitian appears to be a feasible and well-accepted strategy to improve dietary quality and improve cardiovascular risk factors in patients with early kidney disease.
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http://dx.doi.org/10.1053/j.jrn.2019.03.080DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6842073PMC
January 2020

Evaluating the effectiveness and implementation of evidence-based treatment: A multisite hybrid design.

Am Psychol 2019 May-Jun;74(4):459-473. Epub 2018 Jul 19.

Department of Psychology.

The gap between treatment development and efficacy testing to scaled up implementations of evidence-based treatment (EBT) is an estimated 20 years, and hybrid research designs aim to reduce the gap. One was used for a multisite study in cancer control, testing coprimary aims: (a) determine the feasibility and utility of a flexible EBT implementation strategy and (b) determine the clinical effectiveness of an EBT as implemented by newly trained providers. Therapists from 15 diverse sites implemented the biobehavioral intervention (BBI) for cancer patients ( = 158) as part of standard care. For implementation, therapists determined treatment format, number of sessions, and so forth and reported session-by-session fidelity. Patients completed fidelity and outcome assessments. Results showed therapists BBI implementation was done with fidelity, for example, session "dose" (59%), core content coverage (60-70%), and others. Patient reported fidelity was favorable and comparable to the BBI efficacy trial. Effectiveness data show the primary outcome, patients' scores on the Profile of Mood States total mood disturbance, significantly improved (² = 0.06, β = -0.24, < .01) as did a secondary outcome, physical activity (² = 0.02, β = 0.13, < .05). This first use of a hybrid design in health psychology provided support for a novel strategy that allowed providers implementation flexibility. Still, the EBT was delivered with fidelity and in addition, therapists generated novel procedures to enhance setting-specific usage of BBI and its ultimate effectiveness with patients. This research is an example of translational research spanning theory and efficacy tests to dissemination and implementation. (PsycINFO Database Record (c) 2019 APA, all rights reserved).
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http://dx.doi.org/10.1037/amp0000309DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6339615PMC
May 2020

Benefits of reminiscence therapy.

Nurs Stand 2017 Aug;31(52):36

Bournemouth University.

During my second placement in my first year of training, I was working in a community hospital where I helped to care for an older male patient, who I will call Ben.
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http://dx.doi.org/10.7748/ns.31.52.36.s39DOI Listing
August 2017

See the person behind the patient.

Nurs Stand 2017 Apr;31(35):34

Bournemouth University.

During my first clinical placement on a surgical ward, I helped care for a female patient with peritoneal cancer. The patient, who I will call Jane, was about 60 years old and was receiving palliative care.
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http://dx.doi.org/10.7748/ns.31.35.34.s41DOI Listing
April 2017

β-Catenin Stabilization in Skin Fibroblasts Causes Fibrotic Lesions by Preventing Adipocyte Differentiation of the Reticular Dermis.

J Invest Dermatol 2016 06 20;136(6):1130-1142. Epub 2016 Feb 20.

Centre for Stem Cells and Regenerative Medicine, King's College London, Guy's Hospital, Great Maze Pond, London SE1 9RT, UK. Electronic address:

The Wnt/β-catenin pathway plays a central role in epidermal homeostasis and regeneration, but how it affects fibroblast fate decisions is unknown. We investigated the effect of targeted β-catenin stabilization in dermal fibroblasts. Comparative gene expression profiling of stem cell antigen 1(-) (Sca1(-)) and Sca1(+) neonatal fibroblasts from upper and lower dermis, respectively, confirmed that Sca1(+) cells had a preadipocyte signature and showed differential expression of Wnt/β-catenin-associated genes. By targeting all fibroblasts or selectively targeting Dlk1(+) lower dermal fibroblasts, we found that β-catenin stabilization between developmental stages E16.5 and P2 resulted in a reduction in the dermal adipocyte layer with a corresponding increase in dermal fibrosis and an altered hair cycle. The fibrotic phenotype correlated with a reduction in the potential of Sca1(+) fibroblasts to undergo adipogenic differentiation ex vivo. Our findings indicate that Wnt/β-catenin signaling controls adipogenic cell fate within the lower dermis, which potentially contributes to the pathogenesis of fibrotic skin diseases.
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http://dx.doi.org/10.1016/j.jid.2016.01.036DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4874948PMC
June 2016

Erratum to: Examination of the Beck Depression Inventory-II Factor Structure Among Bariatric Surgery Candidates.

Obes Surg 2015 Jul;25(7):1161

Department of Psychology, Keiser University, Port Saint Lucie Campus, 10330 South Federal Highway, Port St. Lucie, FL, 34952, USA,

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http://dx.doi.org/10.1007/s11695-015-1587-9DOI Listing
July 2015

Anaphylaxis in America: A national physician survey.

J Allergy Clin Immunol 2015 Mar 7;135(3):830-3. Epub 2015 Jan 7.

Department of Pediatrics, Division of Allergy and Immunology, Johns Hopkins University School of Medicine, Baltimore, Md. Electronic address:

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http://dx.doi.org/10.1016/j.jaci.2014.10.049DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4859205PMC
March 2015

Examination of the Beck Depression Inventory-II Factor Structure Among Bariatric Surgery Candidates.

Obes Surg 2015 Jul;25(7):1155-60

Department of Psychology, Keiser University, Port Saint Lucie Campus, 10330 South Federal Highway, Port St. Lucie, FL, 34952, USA,

Background: The Beck Depression Inventory-II (BDI-II) is frequently used to evaluate bariatric patients in clinical and research settings; yet, there are limited data regarding the factor structure of the BDI-II with a bariatric surgery population.

Methods: Exploratory factor analysis (EFA) using principal axis factoring with oblimin rotation was employed with data from 1228 consecutive presurgical bariatric candidates. Independent t tests were used to examine potential differences between sexes. Confirmatory factor analysis (CFA) was conducted with the next 383 consecutive presurgical patients to evaluate the proposed model based on EFA results.

Results: EFA revealed three factors: negative perceptions, diminished vigor, and cognitive dysregulation, each with adequate internal consistency. Six BDI-II items did not load significantly on any of the three factors. CFA results largely supported the proposed model.

Conclusions: Results suggest that dimensions of depression for presurgical bariatric candidates vary from other populations and raise important caveats regarding the utility of the BDI-II in bariatric research.
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http://dx.doi.org/10.1007/s11695-014-1506-5DOI Listing
July 2015

Internalized weight bias in weight-loss surgery patients: psychosocial correlates and weight loss outcomes.

Obes Surg 2014 Dec;24(12):2195-9

Center for Obesity Research and Education, Temple University, 3223 N. Broad Street, Suite 175, Philadelphia, PA, 19140, USA,

Purpose: In this study, we examined the relationship between pre-operative internalized weight bias and 12-month post-operative weight loss in adult bariatric surgery patients.

Methods: Bariatric surgery patients (n=170) from one urban and one rural medical center completed an internalized weight bias measure (the weight bias internalization scale, WBIS) and a depression survey (Beck depression inventory-II, BDI-II) before surgery, and provided consent to access their medical records.

Results: Participants (BMI=47.8 kg/m2, age=45.7 years) were mostly female (82.0 %), White (89.5 %), and underwent gastric bypass (83.6 %). The average WBIS score by item was 4.54 ± 1.3. Higher pre-operative WBIS scores were associated with diminished weight loss at 12 months after surgery (p=0.035). Pre-operative WBIS scores were positively associated with depressive symptoms (p<0.001).

Conclusion: Greater internalized weight bias was associated with more depressive symptoms before surgery and less weight loss 1 year after surgery.
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http://dx.doi.org/10.1007/s11695-014-1455-zDOI Listing
December 2014

Engaging patients in public policy advocacy.

Ann Am Thorac Soc 2014 Feb;11(2):260-3

1 Asthma and Allergy Foundation of America, Landover, Maryland; and.

Health professionals can and should be game-changing influencers of U.S. health policies. The American Thoracic Society (ATS) is enabling its members to advocate on important issues through such initiatives as the Breathing Better Alliance network and the annual ATS Hill Day. Patients are also organizing to make their voices heard by participating in the member organizations of the ATS Public Advisory Roundtable and by accompanying ATS members and staff on visits to legislators and government regulators. If we join together, we can amplify our messages and promote better health policies. Doing so will require us to embrace a partnership steeped in trust and hope.
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http://dx.doi.org/10.1513/AnnalsATS.201311-398ARDOI Listing
February 2014

Anaphylaxis in America: the prevalence and characteristics of anaphylaxis in the United States.

J Allergy Clin Immunol 2014 Feb 18;133(2):461-7. Epub 2013 Oct 18.

Department of Pediatrics and Child Health, Section of Allergy and Clinical Immunology, University of Manitoba, Winnipeg, Manitoba, Canada.

Background: Although anaphylaxis is recognized as an important life-threatening condition, data are limited regarding its prevalence and characteristics in the general population.

Objective: We sought to estimate the lifetime prevalence and overall characteristics of anaphylaxis.

Methods: Two nationwide, cross-sectional random-digit-dial surveys were conducted. The public survey included unselected adults, whereas the patient survey captured information from household members reporting a prior reaction to medications, foods, insect stings, or latex and idiopathic reactions in the previous 10 years. In both surveys standardized questionnaires queried anaphylaxis symptoms, treatments, knowledge, and behaviors.

Results: The public survey included 1,000 adults, of whom 7.7% (95% CI, 5.7% to 9.7%) reported a prior anaphylactic reaction. Using increasingly stringent criteria, we estimate that 5.1% (95% CI, 3.4% to 6.8%) and 1.6% (95% CI, 0.8% to 2.4%) had probable and very likely anaphylaxis, respectively. The patient survey included 1,059 respondents, of whom 344 reported a history of anaphylaxis. The most common triggers reported were medications (34%), foods (31%), and insect stings (20%). Forty-two percent sought treatment within 15 minutes of onset, 34% went to the hospital, 27% self-treated with antihistamines, 10% called 911, 11% self-administered epinephrine, and 6.4% received no treatment. Although most respondents with anaphylaxis reported 2 or more prior episodes (19% reporting ≥5 episodes), 52% had never received a self-injectable epinephrine prescription, and 60% did not currently have epinephrine available.

Conclusions: The prevalence of anaphylaxis in the general population is at least 1.6% and probably higher. Patients do not appear adequately equipped to deal with future episodes, indicating the need for public health initiatives to improve anaphylaxis recognition and treatment.
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http://dx.doi.org/10.1016/j.jaci.2013.08.016DOI Listing
February 2014

Polyclonal origin and hair induction ability of dermal papillae in neonatal and adult mouse back skin.

Dev Biol 2012 Jun 14;366(2):290-7. Epub 2012 Apr 14.

Epidermal Stem Cell Laboratory, Wellcome Trust Centre for Stem Cell Research, University of Cambridge, Tennis Court Road, Cambridge CB2 1QR, UK.

Hair follicle development and growth are regulated by Wnt signalling and depend on interactions between epidermal cells and a population of fibroblasts at the base of the follicle, known as the dermal papilla (DP). DP cells have a distinct gene expression signature from non-DP dermal fibroblasts. However, their origins are largely unknown. By generating chimeric mice and performing skin reconstitution assays we show that, irrespective of whether DP form during development, are induced by epidermal Wnt activation in adult skin or assemble from disaggregated cells, they are polyclonal in origin. While fibroblast proliferation is necessary for hair follicle formation in skin reconstitution assays, mitotically inhibited cells readily contribute to DP. Although new hair follicles do not usually develop in adult skin, adult dermal fibroblasts are competent to contribute to DP during hair follicle neogenesis, irrespective of whether they originate from skin in the resting or growth phase of the hair cycle or skin with β-catenin-induced ectopic follicles. We propose that during skin reconstitution fibroblasts may be induced to become DP cells by interactions with hair follicle epidermal cells, rather than being derived from a distinct subpopulation of cells.
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http://dx.doi.org/10.1016/j.ydbio.2012.03.016DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3384004PMC
June 2012

Reprogramming adult dermis to a neonatal state through epidermal activation of β-catenin.

Development 2011 Dec 26;138(23):5189-99. Epub 2011 Oct 26.

Wellcome Trust Centre for Stem Cell Research, University of Cambridge, Tennis Court Road, Cambridge CB2 1QR, UK.

Hair follicle formation depends on reciprocal epidermal-dermal interactions and occurs during skin development, but not in adult life. This suggests that the properties of dermal fibroblasts change during postnatal development. To examine this, we used a PdgfraEGFP mouse line to isolate GFP-positive fibroblasts from neonatal skin, adult telogen and anagen skin and adult skin in which ectopic hair follicles had been induced by transgenic epidermal activation of β-catenin (EF skin). We also isolated epidermal cells from each mouse. The gene expression profile of EF epidermis was most similar to that of anagen epidermis, consistent with activation of β-catenin signalling. By contrast, adult dermis with ectopic hair follicles more closely resembled neonatal dermis than adult telogen or anagen dermis. In particular, genes associated with mitosis were upregulated and extracellular matrix-associated genes were downregulated in neonatal and EF fibroblasts. We confirmed that sustained epidermal β-catenin activation stimulated fibroblasts to proliferate to reach the high cell density of neonatal skin. In addition, the extracellular matrix was comprehensively remodelled, with mature collagen being replaced by collagen subtypes normally present only in developing skin. The changes in proliferation and extracellular matrix composition originated from a specific subpopulation of fibroblasts located beneath the sebaceous gland. Our results show that adult dermis is an unexpectedly plastic tissue that can be reprogrammed to acquire the molecular, cellular and structural characteristics of neonatal dermis in response to cues from the overlying epidermis.
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http://dx.doi.org/10.1242/dev.064592DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3210498PMC
December 2011

Lrig1 expression defines a distinct multipotent stem cell population in mammalian epidermis.

Cell Stem Cell 2009 May;4(5):427-39

Laboratory for Epidermal Stem Cell Biology, Wellcome Trust Centre for Stem Cell Research, University of Cambridge, Cambridge, UK.

Lrig1 is a marker of human interfollicular epidermal stem cells and helps maintain stem cell quiescence. We show that, in mouse epidermis, Lrig1 defines the hair follicle junctional zone adjacent to the sebaceous glands and infundibulum. Lrig1 is a Myc target gene; loss of Lrig1 increases the proliferative capacity of stem cells in culture and results in epidermal hyperproliferation in vivo. Lrig1-expressing cells can give rise to all of the adult epidermal lineages in skin reconstitution assays. However, during homeostasis and on retinoic acid stimulation, they are bipotent, contributing to the sebaceous gland and interfollicular epidermis. beta-catenin activation increases the size of the junctional zone compartment, and loss of Lrig1 causes a selective increase in beta-catenin-induced ectopic hair follicle formation in the interfollicular epidermis. Our results suggest that Lrig1-positive cells constitute a previously unidentified reservoir of adult mouse interfollicular epidermal stem cells.
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http://dx.doi.org/10.1016/j.stem.2009.04.014DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2698066PMC
May 2009

Integrated functions of Pax3 and Pax7 in the regulation of proliferation, cell size and myogenic differentiation.

PLoS One 2009 16;4(2):e4475. Epub 2009 Feb 16.

Dubowitz Neuromuscular Centre, UCL Institute of Child Health, London, United Kingdom.

Pax3 and Pax7 are paired-box transcription factors with roles in developmental and adult regenerative myogenesis. Pax3 and Pax7 are expressed by postnatal satellite cells or their progeny but are down regulated during myogenic differentiation. We now show that constitutive expression of Pax3 or Pax7 in either satellite cells or C2C12 myoblasts results in an increased proliferative rate and decreased cell size. Conversely, expression of dominant-negative constructs leads to slowing of cell division, a dramatic increase in cell size and altered morphology. Similarly to the effects of Pax7, retroviral expression of Pax3 increases levels of Myf5 mRNA and MyoD protein, but does not result in sustained inhibition of myogenic differentiation. However, expression of Pax3 or Pax7 dominant-negative constructs inhibits expression of Myf5, MyoD and myogenin, and prevents differentiation from proceeding. In fibroblasts, expression of Pax3 or Pax7, or dominant-negative inhibition of these factors, reproduce the effects on cell size, morphology and proliferation seen in myoblasts. Our results show that in muscle progenitor cells, Pax3 and Pax7 function to maintain expression of myogenic regulatory factors, and promote population expansion, but are also required for myogenic differentiation to proceed.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0004475PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2637421PMC
April 2009

Developing an integrated primary care practice: strategies, techniques, and a case illustration.

J Clin Psychol 2009 Mar;65(3):268-80

Department of Psychological and Brain Sciences, Indiana University, Bloomington, IN 47405, USA.

Numerous studies have now demonstrated that integrating behavioral health and medical care can reduce medical costs, improve patient and provider satisfaction, and enhance clinical outcomes. Given this, one might expect that behavioral health programs would be fully integrated into primary care clinics across the country, but in fact integrated primary care programs remain quite rare. One reason for this discrepancy is that implementing such programs has proven to be extraordinarily challenging. Most of the integrated programs that are currently operating successfully are in settings where professionals are all members of the same health care system (e.g., HMOs, the Veterans Administration, Departments of Family Practice, etc.). Many providers, however, are in communities where various services are provided in different locations from different organizations that have very different clinical, administrative, and financial structures. In these situations, the challenges are even greater. The authors describe a set of strategies and techniques providers can use to move their health care system toward a higher level of integration and illustrate how they applied these steps to develop and assess the impact of an integrated primary care program in the state of Rhode Island.
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http://dx.doi.org/10.1002/jclp.20552DOI Listing
March 2009

Isolation and grafting of single muscle fibres.

Methods Mol Biol 2009 ;482:319-30

Wellcome Trust Centre for Stem Cell Research, University of Cambridge, Cambridge, UK.

Satellite cells are mononucleate muscle precursor cells resident beneath the basal lamina, which surrounds each skeletal muscle fibre. Normally quiescent in adult muscle, in response to muscle damage satellite cells are activated and proliferate to generate a pool of muscle precursor cells, which subsequently differentiate and fuse together to repair and replace terminally differentiated muscle fibre syncytia. Cells prepared by enzymatic digestion of whole muscle tissue are likely to contain myogenic cells derived both from the satellite cell niche and from other populations in the muscle interstitium and vasculature. Single muscle fibre preparations, in which satellite cells retain their normal anatomical position beneath the basal lamina, are free of interstitial and vascular tissue and can therefore be used to investigate satellite cell behaviour in the absence of other myogenic cell types. Here, we describe methods for the isolation of viable muscle fibres and for grafting of muscle fibres and their associated satellite cells into mouse muscles to assess the contribution of satellite cells to muscle regeneration.
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http://dx.doi.org/10.1007/978-1-59745-060-7_20DOI Listing
February 2009

Dynamic regulation of retinoic acid-binding proteins in developing, adult and neoplastic skin reveals roles for beta-catenin and Notch signalling.

Dev Biol 2008 Dec 12;324(1):55-67. Epub 2008 Sep 12.

Wellcome Trust Centre for Stem Cell Research, University of Cambridge, Tennis Court Road, Cambridge CB2 1QR, UK.

Retinoic acid (RA) signalling is essential for epidermal differentiation; however, the mechanisms by which it acts are largely unexplored. Partitioning of RA between different nuclear receptors is regulated by RA-binding proteins. We show that cellular RA-binding proteins CRABP1 and CRABP2 and the fatty acid-binding protein FABP5 are dynamically expressed during skin development and in adult tissue. CRABP1 is expressed in embryonic dermis and in the stroma of skin tumours, but confined to the hair follicle dermal papilla in normal postnatal skin. CRABP2 and FABP5 are expressed in the differentiating cells of sebaceous gland, interfollicular epidermis and hair follicles, with FABP5 being a prominent marker of sebaceous glands and anagen follicle bulbs. All three proteins are upregulated in response to RA treatment or Notch activation and are negatively regulated by Wnt/beta-catenin signalling. Ectopic follicles induced by beta-catenin arise from areas of the sebaceous gland that have lost CRABP2 and FABP5; conversely, inhibition of hair follicle formation by N-terminally truncated Lef1 results in upregulation of CRABP2 and FABP5. Our findings demonstrate that there is dynamic regulation of RA signalling in different regions of the skin and provide evidence for interactions between the RA, beta-catenin and Notch pathways.
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http://dx.doi.org/10.1016/j.ydbio.2008.08.034DOI Listing
December 2008

A population of myogenic stem cells that survives skeletal muscle aging.

Stem Cells 2007 Apr 11;25(4):885-94. Epub 2007 Jan 11.

The Dubowitz Neuromuscular Unit, Department of Paediatrics, Imperial College London, Hammersmith Hospital, London, U.K.

Age-related decline in integrity and function of differentiated adult tissues is widely attributed to reduction in number or regenerative potential of resident stem cells. The satellite cell, resident beneath the basal lamina of skeletal muscle myofibers, is the principal myogenic stem cell. Here we have explored the capacity of satellite cells within aged mouse muscle to regenerate skeletal muscle and to self-renew using isolated myofibers in tissue culture and in vivo. Satellite cells expressing Pax7 were depleted from aged muscles, and when aged myofibers were placed in culture, satellite cell myogenic progression resulted in apoptosis and fewer total differentiated progeny. However, a minority of cultured aged satellite cells generated large clusters of progeny containing both differentiated cells and new cells of a quiescent satellite-cell-like phenotype characteristic of self-renewal. Parallel in vivo engraftment assays showed that, despite the reduction in Pax7(+) cells, the satellite cell population associated with individual aged myofibers could regenerate muscle and self-renew as effectively as the larger population of satellite cells associated with young myofibers. We conclude that a minority of satellite cells is responsible for adult muscle regeneration, and that these stem cells survive the effects of aging to retain their intrinsic potential throughout life. Thus, the effectiveness of stem-cell-mediated muscle regeneration is determined by both extrinsic environmental influences and diversity in intrinsic potential of the stem cells themselves.
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http://dx.doi.org/10.1634/stemcells.2006-0372DOI Listing
April 2007

Pax7 and myogenic progression in skeletal muscle satellite cells.

J Cell Sci 2006 May 11;119(Pt 9):1824-32. Epub 2006 Apr 11.

Muscle Cell Biology Group, Medical Research Council Clinical Sciences Centre, Imperial College London, Hammersmith Hospital Campus, Du Cane Road, London, W12 0NN, UK.

Skeletal muscle growth and regeneration are attributed to satellite cells - muscle stem cells resident beneath the basal lamina that surrounds each myofibre. Quiescent satellite cells express the transcription factor Pax7 and when activated, coexpress Pax7 with MyoD. Most then proliferate, downregulate Pax7 and differentiate. By contrast, others maintain Pax7 but lose MyoD and return to a state resembling quiescence. Here we show that Pax7 is able to drive transcription in quiescent and activated satellite cells, and continues to do so in those cells that subsequently cease proliferation and withdraw from immediate differentiation. We found that constitutive expression of Pax7 in satellite-cell-derived myoblasts did not affect MyoD expression or proliferation. Although maintained expression of Pax7 delayed the onset of myogenin expression it did not prevent, and was compatible with, myogenic differentiation. Constitutive Pax7 expression in a Pax7-null C2C12 subclone increased the proportion of cells expressing MyoD, showing that Pax7 can act genetically upstream of MyoD. However these Pax7-null cells were unable to differentiate into normal myotubes in the presence of Pax7. Therefore Pax7 may be involved in maintaining proliferation and preventing precocious differentiation, but does not promote quiescence.
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http://dx.doi.org/10.1242/jcs.02908DOI Listing
May 2006

Satellite cell self-renewal.

Curr Opin Pharmacol 2006 Jun 24;6(3):301-6. Epub 2006 Mar 24.

The Dubowitz Neuromuscular Unit, Department of Paediatrics, Imperial College London, Hammersmith Hospital, Du Cane Road, London W12 ONN, UK.

Regeneration of adult skeletal muscle involves the activation, proliferation and differentiation of satellite cells - quiescent tissue-specific stem cells occupying a specialised niche beneath the basal laminae of myofibres. Recent studies show that transplanted satellite cells both generate new muscle and undergo self-renewal. Data from cell culture experiments suggest that self-renewal occurs through the return to quiescence of cycling progeny. Several molecules have been implicated in the regulation of satellite cell quiescence, activation and renewal, including the transcription factors Pax7, MyoD and Myf5, the cell-surface glycoprotein CD34, and the membrane lipid sphingomyelin. Evidence suggests that non-satellite cell types from muscle interstitium and bone marrow also give rise to myonuclei, although their contributions relative to the satellite cell remain to be established.
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http://dx.doi.org/10.1016/j.coph.2006.01.006DOI Listing
June 2006

Self-renewal of the adult skeletal muscle satellite cell.

Cell Cycle 2005 Oct 23;4(10):1338-41. Epub 2005 Oct 23.

Muscle Cell Biology Group, MRC Clinical Sciences Centre, Imperial College Faculty of Medicine, Hammersmith Hospital, London, UK.

The concept of the stem cell has evolved in dynamic systems such as those involved in embryonic development and, in the adult, in tissues such as blood and skin which are continuously renewed. It has proved difficult to establish whether stem cell mechanisms underlie the maintenance of the more stable tissues that form the majority of the adult body. We have investigated skeletal muscle, a low-turnover and largely postmitotic tissue which nevertheless maintains a remarkable capacity to regenerate itself following injury. The contractile units of muscle are myofibers, elongated syncytial cells each containing many hundreds of postmitotic myonuclei. Satellite cells are resident beneath the basal lamina of myofibers and function as myogenic precursors during muscle regeneration. We have recently demonstrated that as few as seven Pax7(+) satellite cells associated with one myofiber can regenerate a hundred or more new myofibers containing thousands of myonuclei. Satellite cells also undergo self-renewal, giving them the ability to participate in multiple rounds of injury-induced regeneration. The satellite cell may thus serve as a prototype for stem cell function in stable adult tissues: a tissue-specific progenitor which is normally quiescent but which has self-renewal properties similar to those of better known stem cells.
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http://dx.doi.org/10.4161/cc.4.10.2114DOI Listing
October 2005

Direct isolation of satellite cells for skeletal muscle regeneration.

Science 2005 Sep 1;309(5743):2064-7. Epub 2005 Sep 1.

CNRS Unité de Recherche Associée 2578, Department of Developmental Biology, INSERM, Pasteur Institute, 75724 Paris Cedex 15, France.

Muscle satellite cells contribute to muscle regeneration. We have used a Pax3(GFP/+) mouse line to directly isolate (Pax3)(green fluorescent protein)-expressing muscle satellite cells, by flow cytometry from adult skeletal muscles, as a homogeneous population of small, nongranular, Pax7+, CD34+, CD45-, Sca1- cells. The flow cytometry parameters thus established enabled us to isolate satellite cells from wild-type muscles. Such cells, grafted into muscles of mdx nu/nu mice, contributed both to fiber repair and to the muscle satellite cell compartment. Expansion of these cells in culture before engraftment reduced their regenerative capacity.
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http://dx.doi.org/10.1126/science.1114758DOI Listing
September 2005

Stem cell function, self-renewal, and behavioral heterogeneity of cells from the adult muscle satellite cell niche.

Cell 2005 Jul;122(2):289-301

Muscle Cell Biology Group, Medical Research Council Clinical Sciences Centre, Imperial College Faculty of Medicine, Hammersmith Hospital, Du Cane Road, London W12 ONN, UK.

Satellite cells are situated beneath the basal lamina that surrounds each myofiber and function as myogenic precursors for muscle growth and repair. The source of satellite cell renewal is controversial and has been suggested to be a separate circulating or interstitial stem cell population. Here, we transplant single intact myofibers into radiation-ablated muscles and demonstrate that satellite cells are self-sufficient as a source of regeneration. As few as seven satellite cells associated with one transplanted myofiber can generate over 100 new myofibers containing thousands of myonuclei. Moreover, the transplanted satellite cells vigorously self-renew, expanding in number and repopulating the host muscle with new satellite cells. Following experimental injury, these cells proliferate extensively and regenerate large compact clusters of myofibers. Thus, within a normally stable tissue, the satellite cell exhibits archetypal stem cell properties and is competent to form the basal origin of adult muscle regeneration.
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http://dx.doi.org/10.1016/j.cell.2005.05.010DOI Listing
July 2005

Randomized, controlled trial of written emotional expression and benefit finding in breast cancer patients.

J Clin Oncol 2002 Oct;20(20):4160-8

Department of Psychology, University of Kansas, Lawrence, KS 66045, USA.

Purpose: Expressing emotions and finding benefits regarding stressful experiences have been associated in correlational research with positive adjustment. A randomized trial was performed to compare effects of experimentally induced written emotional disclosure and benefit finding with a control condition on physical and psychological adjustment to breast cancer and to test whether outcomes varied as a function of participants' cancer-related avoidance.

Patients And Methods: Early-stage breast cancer patients completing medical treatment were assigned randomly to write over four sessions about (1) their deepest thoughts and feelings regarding breast cancer (EMO group; n = 21), (2) positive thoughts and feelings regarding their experience with breast cancer (POS group; n = 21), or (3) facts of their breast cancer experience (CTL group; n = 18). Psychological (eg, distress) and physical (perceived somatic symptoms and medical appointments for cancer-related morbidities) outcomes were assessed at 1- and 3-month follow-ups.

Results: A significant condition x cancer-related avoidance interaction emerged on psychological outcomes; EMO writing was relatively effective for women low in avoidance, and induced POS writing was more useful for women high in avoidance. Significant effects of experimental condition emerged on self-reported somatic symptoms (P =.0183) and medical appointments for cancer-related morbidities (P =.0069). Compared with CTL participants at 3 months, the EMO group reported significantly decreased physical symptoms, and EMO and POS participants had significantly fewer medical appointments for cancer-related morbidities.

Conclusion: Experimentally induced emotional expression and benefit finding regarding early-stage breast cancer reduced medical visits for cancer-related morbidities. Effects on psychological outcomes varied as a function of cancer-related avoidance.
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http://dx.doi.org/10.1200/JCO.2002.08.521DOI Listing
October 2002