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1.
Int J Nurs Stud ; 116: 103903, 2021 Apr.
Article in English | MEDLINE | ID: mdl-33637295

ABSTRACT

BACKGROUND AND OBJECTIVE: The number of studies in the area of self-care is growing and international researchers are increasingly developing self-care interventions to improve outcomes of individual patients and communities. However, growth of the evidence is still slow due to challenges with designing and testing self-care interventions. In this article we address major methodological challenges with regard to the definition of self-care, use of theory, and research design, intended to provide guidance to researchers in this field. METHOD: During the inaugural conference of the International Center for Self-Care Research held in Rome, Italy in June 2019 we identified important issues in existing self-care research. Discussion and literature review lead to eight recommendation for future self-care research. RESULTS: In preparation, begin with a theoretically sound definition of self-care. In planning the intervention, build on and extend previous studies. Use theory to develop self-care interventions and consider translational models to guide development, evaluation and implementation of complex self-care interventions. Employ a study design that fits the current phase and objectives of the research and measure self-care and related factors carefully. In reporting, describe the sample and setting sufficiently so that others can draw conclusions about generalizability and applicability to their practice and patient population. In interpretation, describe how the intervention is assumed to work (causal assumptions) and its key components. CONCLUSION: Our review of existing self-care research clearly illustrates that the recommendations we provide are needed if we are to substantially grow the evidence base supporting self-care. Embracing a core set of principles will allow us to build on each other's work. Tweetable abstract: A core set of methodological principles is needed to substantially grow the evidence base supporting self-care.


Subject(s)
Self Care , Humans , Italy
2.
Int J Nurs Stud ; 105: 103555, 2020 May.
Article in English | MEDLINE | ID: mdl-32199150

ABSTRACT

BACKGROUND AND OBJECTIVE: The number of studies in the area of self-care is growing and international researchers are increasingly developing self-care interventions to improve outcomes of individual patients and communities. However, growth of the evidence is still slow due to challenges with designing and testing self-care interventions. In this article we address major methodological challenges with regard to the definition of self-care, use of theory, and research design, intended to provide guidance to researchers in this field. METHOD: During the inaugural conference of the International Center for Self-Care Research held in Rome, Italy in June 2019 we identified important issues in existing self-care research. Discussion and literature review lead to eight recommendation for future self-care research. RESULTS: In preparation, begin with a theoretically sound definition of self-care. In planning the intervention, build on and extend previous studies. Use theory to develop self-care interventions and consider translational models to guide development, evaluation and implementation of complex self-care interventions. Employ a study design that fits the current phase and objectives of the research and measure self-care and related factors carefully. In reporting, describe the sample and setting sufficiently so that others can draw conclusions about generalizability and applicability to their practice and patient population. In interpretation, describe how the intervention is assumed to work (causal assumptions) and its key components. CONCLUSION: Our review of existing self-care research clearly illustrates that the recommendations we provide are needed if we are to substantially grow the evidence base supporting self-care. Embracing a core set of principles will allow us to build on each other's work. Tweetable abstract: A core set of methodological principles is needed to substantially grow the evidence base supporting self-care.


Subject(s)
Evidence-Based Nursing , Research Design , Self Care , Humans
3.
Eur J Cancer Care (Engl) ; 19(5): 682-9, 2010 Sep.
Article in English | MEDLINE | ID: mdl-19912306

ABSTRACT

The aim of this paper is to investigate the perceptions of patients and family members with regard to care received for cancer cachexia. A qualitative study recruited 27 participants, of which 15 were patients with advanced cancer who had primary cachexia and 12 were family members. Participants were recruited from a regional cancer centre in the UK. All participants took part in a domiciliary interview, which was transcribed verbatim for analysis. A major finding from analysis was 'lack of response from health care professionals' in relation to cancer cachexia management. This finding illuminated that patients and their family members wanted three things from healthcare professionals. They wanted their profound weight loss acknowledged, they wanted information about it and why it was happening and they wanted interventions to deal with it. This paper provides powerful messages for healthcare professionals and highlights the needs of patients and their family regarding cancer cachexia management. Patients and their families want this problem addressed by healthcare professionals. This client group requires supportive healthcare interventions, so that they can understand the nature and impact of this syndrome.


Subject(s)
Attitude of Health Personnel , Cachexia/etiology , Family , Neoplasms/complications , Adolescent , Adult , Aged , Aged, 80 and over , Cachexia/diet therapy , Cachexia/nursing , Family/psychology , Female , Humans , Male , Middle Aged , Neoplasms/nursing , Patient Education as Topic , Qualitative Research , United Kingdom , Weight Loss , Young Adult
4.
Cleft Palate Craniofac J ; 46(2): 117-23, 2009 Mar.
Article in English | MEDLINE | ID: mdl-19254061

ABSTRACT

OBJECTIVE: The objective of this study was to explore the prevalence, range of reported symptoms, and clinical risk factors of obstructive sleep apnea in preschool children with cleft lip and/or palate. DESIGN: Questionnaires were distributed to parents/guardians of all children from birth to 5 years of age who were followed by the cleft clinic. RESULTS: Questionnaire data and cleft classification were available for 248 children, with a mean age of 33.4 months. Obstructive sleep apnea was identified in 31.4% of the children. Only 29.5% of children with obstructive sleep apnea had undergone an investigation of these symptoms. The three most common symptoms reported in children with a questionnaire diagnosis of obstructive sleep apnea were (1) "heavy or loud breathing," (2) "easily distracted," and (3) "on the go" or "driven by a motor." The only clinical risk factor associated with a questionnaire diagnosis of obstructive sleep apnea was the presence of a syndrome (chi(2) = 3.5, p = .05). There were no significant differences in risk of obstructive sleep apnea by age, cleft classification, and surgical status. CONCLUSION: Preschool children with cleft lip and/or palate have a risk of obstructive sleep apnea that is as much as five times that of children without cleft. Obstructive sleep apnea appears to be underrecognized in this group of children. Further research is needed to investigate important risk factors for obstructive sleep apnea in children with cleft lip and/or palate.


Subject(s)
Cleft Palate/epidemiology , Mass Screening , Sleep Apnea, Obstructive/epidemiology , Attention/physiology , Child Behavior , Child, Preschool , Cleft Lip/classification , Cleft Lip/epidemiology , Cleft Palate/classification , Female , Humans , Infant , Infant, Newborn , Male , Motor Activity/physiology , New South Wales/epidemiology , Polysomnography , Prevalence , Respiratory Sounds , Risk Factors , Surveys and Questionnaires , Syndrome
5.
Occup Environ Med ; 65(7): 446-51, 2008 Jul.
Article in English | MEDLINE | ID: mdl-18562683

ABSTRACT

The Viral Hepatitis Prevention Board (VHPB) convened a meeting of international experts from the public and private sectors in order to review and evaluate the epidemiology of blood-borne infections in healthcare workers, to evaluate the transmission of hepatitis B and C viruses as an occupational risk, to discuss primary and secondary prevention measures and to review recommendations for infected healthcare workers and (para)medical students. This VHPB meeting outlined a number of recommendations for the prevention and control of viral hepatitis in the following domains: application of standard precautions, panels for counselling infected healthcare workers and patients, hepatitis B vaccination, restrictions on the practice of exposure-prone procedures by infected healthcare workers, ethical and legal issues, assessment of risk and costs, priority setting by individual countries and the role of the VHPB. Participants also identified a number of terms that need harmonization or standardisation in order to facilitate communication between experts.


Subject(s)
Developed Countries , Health Personnel , Hepatitis Viruses , Hepatitis/prevention & control , Infection Control/methods , Occupational Diseases/prevention & control , Allied Health Personnel , Cross Infection/prevention & control , Hepacivirus , Hepatitis B/prevention & control , Hepatitis B/transmission , Hepatitis B virus , Hepatitis C/prevention & control , Hepatitis C/transmission , Humans , Infectious Disease Transmission, Patient-to-Professional/prevention & control , Risk Management , Vaccination
6.
Pediatr Pulmonol ; 43(3): 245-50, 2008 Mar.
Article in English | MEDLINE | ID: mdl-18219693

ABSTRACT

BACKGROUND: Cleft palate is associated with an increased risk of sleep disordered breathing (SDB) but the magnitude of this risk and specific risk factors are unclear. A better understanding of these components of risk will aid the early identification of SDB in this group of children. OBJECTIVE: To describe the clinical characteristics and results of sleep studies undertaken in a cohort of children with cleft palate. Clinical features will be examined to determine potential associations with SDB in this group. METHOD: A retrospective chart review was undertaken to ascertain sleep study results and clinical data for all children with cleft palate. Clinical features of interest included age, gender, syndrome diagnosis, cleft classification, and surgical status. RESULTS: A total of 99 sleep studies were available from 62 children. The sample included a select group of children with cleft palate with features predictive of a high risk of SDB. Baseline sleep study results were consistent with SDB for 87% of children and 28% (15 of 54) of these children demonstrated severe SDB. Uni-variate analysis showed that age, syndrome, and surgical status had significant association with the severity of SDB. On multi-variate analysis only surgical status maintained this association, such that pre-palatoplasty/pharyngoplasty was associated with more severe SDB. Follow-up studies were completed in one-third of the cohort. CONCLUSION: Children with cleft palate appear to have a significant risk of SDB. A prospective study of a population of children with cleft palate is needed to further define the characteristics of this risk and important risk factors.


Subject(s)
Cleft Palate/complications , Polysomnography , Sleep Apnea Syndromes/complications , Adolescent , Child , Child, Preschool , Cleft Palate/classification , Cleft Palate/surgery , Cohort Studies , Female , Follow-Up Studies , Humans , Infant , Infant, Newborn , Male , Palate/surgery , Retrospective Studies , Risk Factors
7.
Palliat Med ; 21(4): 313-22, 2007 Jun.
Article in English | MEDLINE | ID: mdl-17656408

ABSTRACT

BACKGROUND: There is consensus in the literature that the end of life care for patients with chronic illness is suboptimal, but research on the specific needs of this population is limited. AIM: This study aimed to use a mixed methodology and case study approach to explore the palliative care needs of patients with a non-cancer diagnosis from the perspectives of the patient, their significant other and the clinical team responsible for their care. Patients (n = 18) had a diagnosis of either end-stage heart failure, renal failure or respiratory disease. METHODS: The Short Form 36 and Hospital and Anxiety and Depression Questionnaire were completed by all patients. Unstructured interviews were (n = 35) were conducted separately with each patient and then their significant other. These were followed by a focus group discussion (n = 18) with the multiprofessional clinical team. Quantitative data were analysed using simple descriptive statistics and simple descriptive statistics. All qualitative data were taped, transcribed and analysed using Colaizzi's approach to qualitative analysis. FINDINGS: Deteriorating health status was the central theme derived from this analysis. It led to decreased independence, social isolation and family burden. These problems were mitigated by the limited resources at the individual's disposal and the availability of support from hospital and community services. Generally resources and support were perceived as lacking. All participants in this study expressed concerns regarding the patients' future and some patients described feelings of depression or acceptance of the inevitability of imminent death. CONCLUSION: Patients dying from chronic illness in this study had many concerns and unmet clinical needs. Care teams were frustrated by the lack of resources available to them and admitted they were ill-equipped to provide for the individual's holistic needs. Some clinicians described difficulty in talking openly with the patient and family regarding the palliative nature of their treatment. An earlier and more effective implementation of the palliative care approach is necessary if the needs of patients in the final stages of chronic illness are to be adequately addressed.


Subject(s)
Needs Assessment , Palliative Care/methods , Terminal Care/methods , Terminally Ill/psychology , Aged , Aged, 80 and over , Attitude of Health Personnel , Attitude to Death , Caregivers/psychology , Chronic Disease , Female , Focus Groups , Health Status , Humans , Kidney Failure, Chronic/psychology , Lung Diseases/psychology , Male , Middle Aged , Patient Care Planning , Psychiatric Status Rating Scales , Qualitative Research , Renal Insufficiency/psychology
8.
Am J Physiol Heart Circ Physiol ; 292(4): H1747-54, 2007 Apr.
Article in English | MEDLINE | ID: mdl-17122190

ABSTRACT

Cardiac myosin binding protein-C (cMyBP-C) is a thick filament-associated protein that binds tightly to myosin and has a potential role for modulating myocardial contraction. We tested the hypothesis that cMyBP-C 1) contributes to the enhanced in vivo contractile state following beta-adrenergic stimulation and 2) is necessary for myocardial adaptation to chronic increases in afterload. In vivo pressure-volume relations demonstrated that left ventricular (LV) systolic and diastolic function were compromised under basal conditions in cMyBP-C(-/-) compared with WT mice. Moreover, whereas beta-adrenergic treatment significantly improved ejection fraction, peak elastance, and the time to peak elastance in WT mice, these functional indexes remained unchanged in cMyBP-C(-/-) mice. Morphological and functional changes were measured through echocardiography in anesthetized mice following 5 wk of aortic banding. Adaptation to pressure overload was diminished in cMyBP-C(-/-) mice as characterized by a lack of an increase in posterior wall thickness, increased LV diameter, deterioration of fractional shortening, and prolonged isovolumic relaxation time. These results suggest that the absence of cMyBP-C significantly diminishes in vivo LV function and markedly attenuates the increase in LV contractility following beta-adrenergic stimulation or adaptation to pressure overload.


Subject(s)
Carrier Proteins/genetics , Diastole/physiology , Systole/physiology , Ventricular Dysfunction, Left/physiopathology , Ventricular Function, Left/physiology , Adrenergic beta-Agonists/pharmacology , Animals , Calcium/metabolism , Carrier Proteins/metabolism , Diastole/drug effects , Dobutamine/pharmacology , Hypertrophy, Left Ventricular/pathology , Hypertrophy, Left Ventricular/physiopathology , Mice , Mice, Inbred Strains , Mice, Knockout , Myocytes, Cardiac/physiology , Systole/drug effects , Ventricular Dysfunction, Left/pathology , Ventricular Function, Left/drug effects , Ventricular Myosins/metabolism , Ventricular Pressure/drug effects , Ventricular Pressure/physiology
10.
Am J Physiol Heart Circ Physiol ; 280(6): H2732-9, 2001 Jun.
Article in English | MEDLINE | ID: mdl-11356630

ABSTRACT

In myocardium, protein kinase A (PKA) is known to phosphorylate troponin I (TnI) and myosin-binding protein-C (MyBP-C). Here, we used skinned myocardial preparations from nontransgenic (NTG) mouse hearts expressing 100% alpha-tropomyosin (alpha-Tm) to examine the effects of phosphorylated TnI and MyBP-C on Ca2+ sensitivity of force and the rate constant of force redevelopment (k(tr)). Experiments were also done using transgenic (TG) myocardium expressing approximately 60% beta-Tm to test the idea that the alpha-Tm isoform is required to observe the mechanical effects of PKA phosphorylation. Compared with NTG myocardium, TG myocardium exhibited greater Ca2+ sensitivity of force and developed submaximal forces at faster rates. Treatment with PKA reduced Ca2+ sensitivity of force in NTG and TG myocardium, had no effect on maximum k(tr) in either NTG or TG myocardium, and increased the rates of submaximal force development in both kinds of myocardium. These results show that PKA-mediated phosphorylation of myofibrillar proteins significantly alters the static and dynamic mechanical properties of myocardium, and these effects occur regardless of the type of Tm expressed.


Subject(s)
Cyclic AMP-Dependent Protein Kinases/metabolism , Myocardial Contraction/physiology , Myocardium/metabolism , Tropomyosin/metabolism , Animals , Calcium/metabolism , Calcium/pharmacology , Carrier Proteins/metabolism , Cyclic AMP-Dependent Protein Kinases/pharmacology , Electrophoresis, Polyacrylamide Gel , Female , In Vitro Techniques , Isometric Contraction/drug effects , Isometric Contraction/physiology , Male , Mice , Mice, Transgenic , Muscle Proteins/analysis , Muscle Proteins/metabolism , Myocardial Contraction/drug effects , Myofibrils/drug effects , Myofibrils/metabolism , Phosphorylation/drug effects , Stress, Mechanical , Tropomyosin/genetics , Troponin I/metabolism
11.
J Physiol ; 530(Pt 2): 263-72, 2001 Jan 15.
Article in English | MEDLINE | ID: mdl-11208974

ABSTRACT

To determine the ability of strong-binding myosin cross-bridges to activate the myocardial thin filament, we examined the Ca2+ dependence of force and cross-bridge interaction kinetics at 15 degrees C in the absence and presence of a strong-binding, non-force-generating derivative of myosin subfragment-1 (NEM-S1) in chemically skinned myocardium from adult rats. Relative to control conditions, application of 6 microM NEM-S1 significantly increased Ca2+-independent tension, measured at pCa 9.0, from 0.8 +/- 0.3 to 3.7 +/- 0.8 mN mm-2. Furthermore, NEM-S1 potentiated submaximal Ca2+-activated forces and thereby increased the Ca2+ sensitivity of force, i.e. the [Ca2+] required for half-maximal activation (pCa50) increased from pCa 5.85 +/- 0.05 to 5.95 +/- 0.04 (change in pCa50 (dpCa50) = 0.11 +/- 0.02). The augmentation of submaximal force by NEM-S1 was accompanied by a marked reduction in the steepness of the force-pCa relationship for forces less than 0.50 Po (maximum Ca2+-activated force), i.e. the Hill coefficient (n2) decreased from 4.72 +/- 0.38 to 1.54 +/- 0.07. In the absence of NEM-S1, the rate of force redevelopment (ktr) was found to increase from 1.11 +/- 0.21 s-1 at submaximal [Ca2+] (pCa 6.0) to 9.28 +/- 0.41 s-1 during maximal Ca2+ activation (pCa 4.5). Addition of NEM-S1 reduced the Ca2+ dependence of ktr by eliciting maximal values at low levels of Ca2+, i.e. ktr was 9.38 +/- 0.30 s-1 at pCa 6.6 compared to 9.23 +/- 0.27 s-1 at pCa 4. At intermediate levels of Ca2+, ktr was less than maximal but was still greater than values obtained at the same pCa in the absence of NEM-S1. NEM-S1 dramatically reduced both the extent and rate of relaxation from steady-state submaximal force following flash photolysis of the caged Ca2+ chelator diazo-2. These data demonstrate that strongly bound myosin cross-bridges increase the level of thin filament activation in myocardium, which is manifested by an increase in the rate of cross-bridge attachment, potentiation of force at low levels of free Ca2+, and slowed rates of relaxation.


Subject(s)
Actin Cytoskeleton/metabolism , Myocardium/metabolism , Myosins/metabolism , Animals , Chelating Agents , Diazonium Compounds , Female , In Vitro Techniques , Kinetics , Myocardial Contraction/physiology , Myosin Subfragments/physiology , Phenoxyacetates , Photolysis , Rats , Rats, Sprague-Dawley
12.
J Gen Physiol ; 117(2): 133-48, 2001 Feb.
Article in English | MEDLINE | ID: mdl-11158166

ABSTRACT

Regulation of contraction in skeletal muscle is a highly cooperative process involving Ca(2+) binding to troponin C (TnC) and strong binding of myosin cross-bridges to actin. To further investigate the role(s) of cooperation in activating the kinetics of cross-bridge cycling, we measured the Ca(2+) dependence of the rate constant of force redevelopment (k(tr)) in skinned single fibers in which cross-bridge and Ca(2+) binding were also perturbed. Ca(2+) sensitivity of tension, the steepness of the force-pCa relationship, and Ca(2+) dependence of k(tr) were measured in skinned fibers that were (1) treated with NEM-S1, a strong-binding, non-force-generating derivative of myosin subfragment 1, to promote cooperative strong binding of endogenous cross-bridges to actin; (2) subjected to partial extraction of TnC to disrupt the spread of activation along the thin filament; or (3) both, partial extraction of TnC and treatment with NEM-S1. The steepness of the force-pCa relationship was consistently reduced by treatment with NEM-S1, by partial extraction of TnC, or by a combination of TnC extraction and NEM-S1, indicating a decrease in the apparent cooperativity of activation. Partial extraction of TnC or NEM-S1 treatment accelerated the rate of force redevelopment at each submaximal force, but had no effect on kinetics of force development in maximally activated preparations. At low levels of Ca(2+), 3 microM NEM-S1 increased k(tr) to maximal values, and higher concentrations of NEM-S1 (6 or 10 microM) increased k(tr) to greater than maximal values. NEM-S1 also accelerated k(tr) at intermediate levels of activation, but to values that were submaximal. However, the combination of partial TnC extraction and 6 microM NEM-S1 increased k(tr) to virtually identical supramaximal values at all levels of activation, thus, completely eliminating the activation dependence of k(tr). These results show that k(tr) is not maximal in control fibers, even at saturating [Ca(2+)], and suggest that activation dependence of k(tr) is due to the combined activating effects of Ca(2+) binding to TnC and cross-bridge binding to actin.


Subject(s)
Calcium/metabolism , Muscle Contraction/physiology , Muscle Fibers, Fast-Twitch/physiology , Myosin Subfragments/pharmacology , Animals , Cross-Linking Reagents/pharmacology , Ethylmaleimide/pharmacology , In Vitro Techniques , Muscle Contraction/drug effects , Myosin Subfragments/metabolism , Protein Binding/drug effects , Protein Binding/physiology , Psoas Muscles/cytology , Rabbits , Sulfhydryl Reagents/pharmacology , Troponin C/isolation & purification
13.
Prof Nurse ; 16(5): 1091-4, 2001 Feb.
Article in English | MEDLINE | ID: mdl-12029908

ABSTRACT

Research into nurses' knowledge of infection control provided the basis for a hospital training programme. A combined approach by occupational health and infection control specialists developed an appropriate needs-based programme.


Subject(s)
Health Knowledge, Attitudes, Practice , Infection Control , Nurse Clinicians , Nurse's Role , Education, Nursing, Continuing , Hand Disinfection , Humans , Needlestick Injuries/prevention & control , Program Evaluation , Staff Development
14.
J Adv Nurs ; 32(5): 1243-52, 2000 Nov.
Article in English | MEDLINE | ID: mdl-11115010

ABSTRACT

Waiting lists for coronary artery bypass surgery (CABS) are common in many developed countries. Yet, there is limited information available regarding patients' health care needs at this time. This paper reports on a prospective study which aimed to investigate the experience of waiting for CABS from a qualitative perspective. An inductive research approach was used to conduct interviews with 70 randomly selected patients at three intervals over the first year on the waiting list - referral for surgery, again after waiting 6 months (n=49), and finally after waiting for 1 year (n=28). Attrition was mainly caused by surgery having been performed (n=36), although death (n=4) and refusal to participate (n=2) also contributed. Domicilliary interviews were taped and transcribed verbatim. Thematic content analysis identified three central themes in this experience - uncertainty, chest pain and anxiety; with six secondary themes - powerless, dissatisfaction with treatment, anger/frustration, physical incapacity, reduced self-esteem, and altered family and social relationships. The nature and meaning inherent in each theme is described using interview quotations, and a model is proposed which summarizes this data and the relationship between themes. From this analysis, uncertainty, chest pain and anxiety emerge as important indicators of a negative outcome for these patients. This report strongly suggests that patients awaiting bypass surgery require more information regarding the waiting time for such a surgery. Nurses should also offer advice regarding pain management to help improve patients' skills and decrease the fear associated with angina. Nursing intervention and support should also be directed at reducing patients' anxiety levels. This is the first known qualitative study which specifically examines patients' perception of the waiting period prior to bypass surgery. It may therefore provide new evidence on which to base practice for nurses in both hospital and community, and may also stimulate further research in this area.


Subject(s)
Angina Pectoris/psychology , Angina Pectoris/surgery , Attitude to Health , Coronary Artery Bypass/psychology , Waiting Lists , Activities of Daily Living , Adult , Aged , Anger , Anxiety/psychology , Family/psychology , Female , Humans , Male , Middle Aged , Models, Psychological , Northern Ireland , Nursing Methodology Research , Power, Psychological , Prospective Studies , Self Concept , Surveys and Questionnaires
16.
Am J Physiol ; 276(5): H1511-9, 1999 05.
Article in English | MEDLINE | ID: mdl-10330233

ABSTRACT

Normal aging of the rodent heart results in prominent prolongation of the twitch. We tested the hypothesis that increased expression of beta-myosin heavy chain (MHC), as occurs in the normal aging process in the rodent heart, contributes to the prolongation of the twitch by depressing the kinetics of cross-bridge interaction. Using 3-, 9-, 21-, and 33-mo-old male Fischer 344 x Brown Norway F1 hybrid rats, we examined both the rate of tension development (kCa) and unloaded shortening velocity in chemically skinned myocardium. Although kCa in all four age groups was dependent on the level of Ca2+ activation, both submaximal and maximal kCa were significantly slower in 9-, 21-, and 33-mo-old rats relative to 3-mo-old rats. Furthermore, unloaded shortening velocity was significantly reduced in 9-, 21-, and 33-mo-old rats compared with 3-mo-old rats. Collectively, these data strongly suggest that the aging-related increase in beta-MHC expression results in a progressive slowing of cross-bridge interaction kinetics in skinned myocardium, which most likely contributes to the overall aging-dependent reduction in myocardial functional capacity.


Subject(s)
Aging/physiology , Muscle Fibers, Skeletal/physiology , Myocardial Contraction/physiology , Myocardium/metabolism , Myosin Heavy Chains/metabolism , Acetates/pharmacology , Animals , Calcium Chloride/pharmacology , Chelating Agents/pharmacology , Contractile Proteins/analysis , Ethylenediamines/pharmacology , Heart Ventricles/chemistry , Heart Ventricles/cytology , Kinetics , Male , Muscle Fibers, Skeletal/drug effects , Myocardial Contraction/drug effects , Myocardium/chemistry , Myocardium/cytology , Organ Culture Techniques , Organ Size , Photochemistry , Rats , Rats, Inbred F344 , Ventricular Function
17.
J Physiol ; 513 ( Pt 1): 171-83, 1998 Nov 15.
Article in English | MEDLINE | ID: mdl-9782168

ABSTRACT

1. The effects of ventricular myosin heavy chain (MHC) composition on the kinetics of activation and relaxation were examined in both chemically skinned and intact myocardial preparations from adult rats. Thyroid deficiency was induced to alter ventricular MHC isoform expression from approximately 80% alpha-MHC/20% beta-MHC in euthyroid rats to 100% beta-MHC, without altering the expression of thin-filament-associated regulatory proteins. 2. In single skinned myocytes, increased expression of beta-MHC did not significantly affect either maximal Ca2+-activated tension (P0) or the Ca2+ sensitivity of tension (pCa50). However, unloaded shortening velocity (V0) decreased by 80% due to increased beta-MHC expression. 3. The kinetics of activation and relaxation were examined in skinned multicellular preparations using the caged Ca2+ compound DM-nitrophen and caged Ca2+ chelator diazo-2, respectively. Myocardium expressing 100% beta-MHC exhibited apparent rates of submaximal and maximal tension development (kCa) that were 60% lower than in control myocardium, and a 2-fold increase in the half-time for relaxation from steady-state submaximal force. 4. The time courses of cell shortening and intracellular Ca2+ transients were assessed in living, electrically paced myocytes, both with and without beta-adrenergic stimulation (70 nM isoproterenol (isoprenaline)). Thyroid deficiency had no affect on either the extent of myocyte shortening or the resting or peak fura-2 fluorescence ratios. However, induction of beta-MHC expression by thyroid deficiency was associated with increased half-times for myocyte shortening and relengthening and increased half-time for the decay of the fura-2 fluorescence ratio. Qualitatively similar results were obtained in both the absence and the presence of beta-adrenergic stimulation although the beta-agonist accelerated the kinetics of the twitch and the Ca2+ transient. 5. Collectively, these data provide evidence that increased beta-MHC expression contributes significantly to the observed depression of contractile function in thyroid deficient myocardium by slowing the rates of both force development and force relaxation.


Subject(s)
Myocardial Contraction/physiology , Myosin Heavy Chains/chemistry , Myosin Heavy Chains/physiology , Adrenergic beta-Agonists/pharmacology , Animals , Calcium Signaling/drug effects , Chelating Agents/pharmacology , Female , Half-Life , In Vitro Techniques , Isoproterenol/pharmacology , Kinetics , Muscle Relaxation/drug effects , Muscle Relaxation/physiology , Myocardial Contraction/drug effects , Myofibrils/physiology , Photolysis , Rats , Rats, Sprague-Dawley , Thyroid Gland/drug effects , Thyroid Gland/physiology
18.
Circ Res ; 83(6): 602-7, 1998 Sep 21.
Article in English | MEDLINE | ID: mdl-9742055

ABSTRACT

Reductions in sarcomere length (SL) and concomitant increases in interfilament lattice spacing have been shown to decrease the Ca2+ sensitivity of tension in myocardium. We tested the idea that increased lattice spacing influences the SL dependence of isometric tension by reducing the probability of strong interactions of myosin crossbridges with actin, thereby decreasing cooperative activation of the thin filament. Single ventricular myocytes were isolated by enzymatic digestion of rat hearts and were subsequently rapidly skinned. Maximal tension and Ca2+ sensitivity of tension (ie, pCa50) were measured in the absence and presence of N-ethylmaleimide-modified myosin subfragment 1 (NEM-S1) at both short and long SLs. NEM-S1, a strong-binding non-tension-generating derivative of the myosin head, was applied to single skinned myocytes to cooperatively promote strong binding of endogenous myosin crossbridges. Compared with control myocytes at SL of approximately 1.90 microm, application of NEM-S1 markedly increased submaximal Ca2+-activated tensions and thereby increased Ca2+ sensitivity; ie, pCa50 increased from 5.40+/-0.02 to 5.52+/-0.02 pCa units in the presence of NEM-S1. Furthermore, NEM-S1 treatment reversibly eliminated the SL dependence of the Ca2+ sensitivity of tension, in that the DeltapCa50 between short and long lengths was 0. 02+/-0.01 pCa units in the presence of NEM-S1 compared with a DeltapCa50 of 0.10+/-0.01 pCa units in control myocytes. From these results we conclude that the decrease in the Ca2+ sensitivity of tension at short SL results predominantly from decreased cooperative activation of the thin filament due to reductions in the number of strong-binding crossbridges.


Subject(s)
Calcium/pharmacology , Heart Ventricles/cytology , Myosins/metabolism , Animals , Biophysical Phenomena , Biophysics , Ethylmaleimide/pharmacology , Female , Muscle, Skeletal/cytology , Muscle, Skeletal/drug effects , Protein Binding , Rats , Rats, Sprague-Dawley
19.
J Am Diet Assoc ; 98(2): 182-6, 189; quiz 187-8, 1998 Feb.
Article in English | MEDLINE | ID: mdl-12515420

ABSTRACT

Good oral health care and nutrition during pregnancy, infancy, and childhood are essential but often overlooked factors in the growth and development of the teeth and oral cavity. Pregnant women and parents and caregivers of infants and children often receive little guidance about proper preventive dental and oral health care, including fluoride and dietary measures. Pregnant women can maintain their health through proper diet, good oral hygiene, and appropriate use of fluoride. An adequate diet during gestation is important for optimal oral development of the fetus. To promote good oral health in infancy, caregivers need to provide the infant with appropriate amounts of fluoride in addition to a healthful diet. As the teeth erupt into the mouth, the caregiver needs to clean the teeth thoroughly on a daily basis. When solid foods are introduced in later infancy, it is also important to limit the frequency of caries-promoting fermentable carbohydrates between meals. Good oral hygiene habits and dietary practices that emphasize minimum exposure to retentive, fermentable carbohydrates; use of fluoridated water; and a varied, balanced diet should continue throughout childhood to set the stage for optimal oral health for a lifetime.


Subject(s)
Guidelines as Topic , Nutritional Physiological Phenomena , Oral Health/standards , Oral Hygiene , Prenatal Care , Child, Preschool , Dental Care , Dental Caries/prevention & control , Female , Fluorides/administration & dosage , Humans , Infant , Infant, Newborn , Male , Mouth Diseases/prevention & control , Pregnancy , Pregnancy Complications/prevention & control
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