Music Therapy Intervention to Reduce Symptom Burden in Hospice Patients: A Descriptive Study.

Background: Music therapy (MT) offers benefits of improved symptom relief and quality of life at the end of life, but its impact on hospice patients and caregivers needs more research. Objective: To assess the impact of MT intervention on symptom burden and well-being of hospice patients and caregivers. Methods: A total of 18 hospice patients, selected based on scores ≥4 on the revised Edmonton Symptom Assessment System (ESAS-r) items on pain, depression, anxiety, or well-being, participated in MT sessions provided by a board-certified music therapist. Over a period of 2-3 weeks, 3-4 MT sessions were conducted for each. Patient Quality of life (QOL) was assessed using the Linear Analogue Self-Assessment (LASA). Depression and anxiety were measured with the Patient Health Questionnaire-4 (PHQ-4). For the 7 caregivers enrolled, stress levels were measured using the Pearlin role overload measure and LASA. Results: Patients reported a reduction in symptom severity and emotional distress and an increase in QOL. All patients endorsed satisfaction with music therapy, describing it as particularly beneficial for stress relief, relaxation, spiritual support, emotional support, and well-being. Scores on overall QOL and stress were worse for caregivers. Conclusion: This study provides evidence that MT reduces symptom burden and enhances the quality of life for hospice patients. Hospice patients and their caregivers endorsed satisfaction with MT. Given the benefits observed, integrating MT into hospice care regimens could potentially improve patient and caregiver outcomes. Larger studies should be conducted to better assess the impact of MT in this population.

Music Therapy Intervention to Reduce Caregiver Distress at End of Life: A Feasibility Study.

BACKGROUND: Music therapy (MT) can relieve distressing end-of-life symptoms, but little is known regarding its effect on caregivers who are at risk for emotional distress as their loved ones approach death. MEASURES: Quality of life (Linear Analogue Self-Assessment), depressive and anxiety symptoms (Patient Health Questionnaire for Depression and Anxiety), and stress (Role Overload Measure) pre-MT, post-MT and at 6-month follow-up, as well as a satisfaction survey post-MT. INTERVENTION: Single MT session for 20-45 minutes OUTCOMES: 15/20 completed MT intervention, 14 also completed pre-MT and post-MT assessments, and 9 completed assessments at all 3 timepoints. Post-MT satisfaction survey (n=14) showed 100% of caregivers were very satisfied with MT and would recommend to others, and found MT very effective for emotional support (85.7%), stress relief (78.6%), spiritual support (71.4%), general feeling of wellness (71.4%), relaxation (69.2%), and pain relief (33.3%). CONCLUSIONS: Research on MT is feasible for caregivers of inpatient hospice patients. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT03322228.

Impact of Massage Therapy on the Quality of Life of Hospice Patients and Their Caregivers: A Pilot Study.

Evidence for massage therapy (MT) in hospice patients remains limited. We conducted a prospective pilot study on MTs impact on quality of life of hospice patients and caregivers. Patient-caregiver dyads were enrolled if patients scored ≥5 on pain, depression, anxiety, or well-being using the revised Edmonton Symptom Assessment System Revised (ESAS-r). The patient received MT weekly for up to 3 massages with assessments completed at baseline, after each massage, and 1 week after the final massage for patients and at baseline and 1 week after final massage for caregivers. A satisfaction survey was completed at study completion. A pro-rated area under the curve (AUC) was utilized to assess the primary endpoints of change in ESAS-r for patient ratings of pain, depression and anxiety as well as the Linear Analogue Self-Assessment (LASA). Median difference scores (end of study value)-(baseline value) for each participant and caregiver were calculated. Of 27 patients and caregivers enrolled, 25 patients received MT. Fifteen patients completed all 3 MT sessions and were given the final symptom assessment and satisfaction survey and their caregivers completed final assessments. The proportion of patients considered success (AUC > baseline) in the primary endpoints were the following: pain 40.9%, depression 40.9%, anxiety 54.5%, LASA 54.5%. Median difference scores were largely zero indicating no significant temporal change in symptoms. Patients were highly satisfied with MT. This pilot study indicated that MT was a feasible and well-received intervention in our population of patients with inadequately controlled symptoms.

The Impact of Nurse-Led Clinics on the Mortality and Morbidity of Patients with Cardiovascular Diseases: A Systematic Review and Meta-analysis.

BACKGROUND: Nurse-led clinics (NLCs) have been developed in several health specialties in recent years. The aim of this analysis is to summarize and appraise the available evidence about the effectiveness of NLCs on the morbidity and mortality outcomes in patients with cardiovascular diseases (CVDs). METHODS: We searched Cochrane databases, MEDLINE, Web of Science, PubMed, EMBASE, Google Scholar, BIOSIS, and bibliography of secondary sources from inception through February 20, 2013. Studies were selected and data were extracted independently by 2 investigators. Eligible studies were randomized trials of NLCs of patients with CVD. Of 56 potentially relevant articles screened initially, 12 trials met the inclusion criteria. The outcomes of interest were all-cause mortality, cardiovascular mortality, nonfatal myocardial infarction, major adverse cardiac events, revascularization, lipids control, and adherence to antiplatelet medications. We performed random-effects meta-analysis to estimate summary risk ratios and quantified between-studies heterogeneity with the I2 statistic. RESULTS: The 12 trials allocated 4886 patients to NLCs and 4954 patients to usual care. The NLC patients had decreased all-cause mortality (odds ratio, 0.78; 95% confidence interval [CI], 0.65-0.95; P < .01) and myocardial infarction (odds ratio, 0.63; 95% CI, 0.39-1.00; P = .05) and had higher adherence to lipid-lowering medication (odds ratio, 1.57; 95% CI, 1.14-2.17; P = .006) compared with controls. They also had increased adherence to antiplatelet therapy compared with controls (odds ratio, 1.42; 95% CI, 1.01-1.98; P = .04). There was no statistically significant difference in the risk of cardiovascular death (odds ratio, 0.68; 95% CI, 0.40-1.15; P = .68), major adverse cardiac events (odds ratio, 0.79; 95% CI, 0.55-1.14; P = .21),or revascularization (odds ratio, 0.87; 95% CI, 0.66-1.16; P = .36) between NLC patients and controls. CONCLUSIONS: The available evidence suggests a favorable effect of NLCs on all-cause mortality, rate of major adverse cardiac events, and adherence to medications in patients with CVD.

The effect of branched chain amino acids on skeletal muscle mitochondrial function in young and elderly adults.

CONTEXT: A reduction in maximal mitochondrial ATP production rate (MAPR) and mitochondrial DNA (mtDNA) abundance occurs with age in association with muscle weakness and reduced endurance in elderly people. Branched chain amino acids (BCAA) have been extensively used to improve physical performance. OBJECTIVE: The objective was to determine whether an 8-h infusion of BCAA enhances MAPR equally in healthy young and elderly adults. METHODS: Using a crossover study design, we compared the effect BCAA vs. saline infusion in 12 young (23.0 +/- 0.8 yr) and 12 elderly (70.7 +/- 1.1 yr) participants matched for sex and body mass index. Skeletal muscle MAPR and mtDNA abundance were measured in muscle biopsy samples obtained before and at the end of the 8-h infusion. RESULTS: In young participants, MAPR with the substrates glutamate plus malate (supplying electrons to complex I) and succinate plus rotenone (complex II) increased in response to BCAA infusion, relative to a decline in MAPR in response to the saline infusion. In contrast, MAPR was unaffected by BCAA infusion in the elderly participants. Moreover, mtDNA abundance was lower in the elderly compared with the young participants but was unaffected by the BCAA infusion. Insulin and C-peptide concentrations declined over time during the saline infusion, but these declines were prevented by the BCAA infusion. CONCLUSIONS: BCAA increased skeletal muscle MAPR in the young participants in comparison with saline, but this effect was not seen in the elderly participants indicating, that unlike in the young, BCAA does not increase muscle mitochondrial function in the elderly.

Short-term prednisone use antagonizes insulin's anabolic effect on muscle protein and glucose metabolism in young healthy people.

Glucocorticoids cause muscle atrophy and weakness, but the mechanisms for these effects are unclear. The purpose of this study was to test a hypothesis that prednisone (Pred) counteracts insulin's anabolic effects on muscle. A randomized, double-blind cross-over design was used to test the effects of 6 days either Pred (0.8 mg x kg(-1) x day(-1)) or placebo use in seven healthy young volunteers. Protein dynamics were measured across the leg using stable isotope tracers of leucine (Leu) and phenylalanine (Phe) after overnight fast and during a hyperinsulinemic (1.5 microU x min(-1) x kg FFM(-1)) euglycemic clamp with amino acid replacement. Fasting glucose, amino acids, insulin, and glucagon were higher (P < 0.01) on Pred vs. placebo, whereas leg blood flow was 18% lower. However, basal whole body and leg kinetics of Leu and Phe were unaltered by Pred. Insulin infusion increased leg glucose uptake in both trials but was 65% lower with Pred than with placebo. Insulin in both trials similarly suppressed whole body flux of Leu and Phe. Importantly, insulin increased net Leu and Phe balance across the leg and the balance between muscle protein synthesis and breakdown, but these changes were 45-140% lower (P < 0.03) in Pred than in placebo. The present study demonstrates that short-term Pred use in healthy people does not alter whole body or leg muscle protein metabolism during the postaborptive state but causes muscle insulin resistance for both glucose and amino acid metabolism, with a blunted protein anabolism. This interactive effect may lead to muscle atrophy with continued use of glucocorticoids.

Dehydroepiandrosterone replacement therapy in hypoadrenal women: protein anabolism and skeletal muscle function.

OBJECTIVE: To determine whether dehydroepiandrosterone (DHEA) replacement therapy in hypoadrenal women improves performance, muscle protein accretion, and mitochondrial functions. PARTICIPANTS AND METHODS: Thirty-three hypoadrenal women were enrolled in the study from May 1, 2002, through May 31, 2003. Twenty-eight completed a 12-week, prospective, randomized, placebo-controlled, crossover study with either daily placebo or 50 mg of DHEA with a 2-week washout period and then crossed over to the other treatment. Body composition, physical performance, whole-body and muscle protein metabolism, and mitochondrial functions were determined. RESULTS: Administration of DHEA significantly increased plasma levels of DHEA sulfate, testosterone, and androstenedione but did not change body composition, muscle strength, peak aerobic capacity, and whole-body protein turnover or synthesis rates of mitochondrial, sarcoplasmic, or mixed muscle proteins. Muscle mitochondrial oxidative enzymes and messenger RNA (mRNA) levels of genes encoding mitochondrial proteins and nuclear transcription factors did not change after DHEA administration. However, mRNA levels of muscle myosin heavy chain 1 (P=.004), which determines muscle fiber type, and those of insulinlike growth factor binding proteins 4 and 5 significantly decreased (P=.02 and P=.03, respectively). CONCLUSION: Three months of DHEA administration increased DHEA sulfate and androgen levels but had no effect on physical performance, body composition, protein metabolism, or muscle mitochondrial biogenesis in hypoadrenal women. However, lowering of mRNA levels of binding proteins of insulinlike growth factor 1 and myosin heavy chain 1 suggests potential effects of longterm treatment with DHEA on muscle fiber type.

Functional impact of high protein intake on healthy elderly people.

Decline in muscle mass, protein synthesis, and mitochondrial function occurs with age, and amino acids are reported to enhance both muscle protein synthesis and mitochondrial function. It is unclear whether increasing dietary protein intake corrects postabsorptive muscle changes in aging. We determined whether a 10-day diet of high [HP; 3.0 g protein x kg fat-free mass (FFM)(-1) x day(-1)] vs. usual protein intake (UP; 1.5 g protein x kg FFM(-1) x day(-1)) favorably affects mitochondrial function, protein metabolism, and nitrogen balance or adversely affects insulin sensitivity and glomerular filtration rate (GFR) in 10 healthy younger (24+/-1 yr) and 9 older (70+/-2 yr) participants in a randomized crossover study. Net daily nitrogen balance increased equally in young and older participants, but postabsorptive catabolic state also increased, as indicated by higher whole body protein turnover and leucine oxidation with no change in protein synthesis. Maximal muscle mitochondrial ATP production rate was lower in older people, with no change occurring in diet. GFR was lower in older people, and response to HP was significantly different between the two groups, with a significant increase occurring only in younger people, thus widening the differences in GFR between the young and older participants. In conclusion, a short-term high-protein diet increased net daily nitrogen balance but increased the postabsorptive use of protein as a fuel. HP did not enhance protein synthesis or muscle mitochondrial function in either young or older participants. Additionally, widening differences in GFR between young and older patients is a potential cause of concern in using HP diet in older people.

Asian Indians have enhanced skeletal muscle mitochondrial capacity to produce ATP in association with severe insulin resistance.

OBJECTIVE: Type 2 diabetes has become a global epidemic, and Asian Indians have a higher susceptibility to diabetes than Europeans. We investigated whether Indians had any metabolic differences compared with Northern European Americans that may render them more susceptible to diabetes. RESEARCH DESIGN AND METHODS: We studied 13 diabetic Indians, 13 nondiabetic Indians, and 13 nondiabetic Northern European Americans who were matched for age, BMI, and sex. The primary comparisons were insulin sensitivity by hyperinsulinemic-euglycemic clamp and skeletal muscle mitochondrial capacity for oxidative phosphorylation (OXPHOS) by measuring mitochondrial DNA copy number (mtDNA), OXPHOS gene transcripts, citrate synthase activity, and maximal mitochondrial ATP production rate (MAPR). Other factors that may cause insulin resistance were also measured. RESULTS: The glucose infusion rates required to maintain identical glucose levels during the similar insulin infusion rates were substantially lower in diabetic Indians than in the nondiabetic participants (P < 0.001), and they were lower in nondiabetic Indians than in nondiabetic Northern European Americans (P < 0.002). mtDNA (P < 0.02), OXPHOS gene transcripts (P < 0.01), citrate synthase, and MAPR (P < 0.03) were higher in Indians irrespective of their diabetic status. Intramuscular triglyceride, C-reactive protein, interleukin-6, and tumor necrosis factor-alpha concentrations were higher, whereas adiponectin concentrations were lower in diabetic Indians. CONCLUSIONS: Despite being more insulin resistant, diabetic Indians had similar muscle OXPHOS capacity as nondiabetic Indians, demonstrating that diabetes per se does not cause mitochondrial dysfunction. Indians irrespective of their diabetic status had higher OXPHOS capacity than Northern European Americans, although Indians were substantially more insulin resistant, indicating a dissociation between mitochondrial dysfunction and insulin resistance.

Enhancement of muscle mitochondrial function by growth hormone.

CONTEXT: Although GH promotes growth and protein anabolism, which are ATP-dependent processes, the GH effect on mitochondrial regulation remains to be determined. OBJECTIVE: Our objective was to determine the acute effect of GH on mitochondrial oxidative capacity in skeletal muscle of healthy subjects. DESIGN AND SETTING: The study was a randomized crossover design at an academic medical center. PARTICIPANTS: Nine healthy men and women completed the study. INTERVENTION: GH (150 microg/h) or saline was infused for 14 h on separate days, and muscle biopsies were obtained. MAIN OUTCOME MEASURES: Outcome measures included mitochondrial function, gene expression, and protein metabolism. RESULTS: The 4-fold increase in plasma GH caused elevations in plasma IGF-I, insulin, glucose, and free fatty acids and a shift in fuel selection, with less carbohydrate (-69%) and leucine (-43%) oxidation and 29% more fat oxidation. Muscle mitochondrial ATP production rate and citrate synthase activity were increased 16-35% in response to GH. GH also resulted in higher abundance of muscle mRNAs encoding IGF-I, mitochondrial proteins from the nuclear (cytochrome c oxidase subunit 4) and mitochondrial (cytochrome c oxidase subunit 3) genomes, the nuclear-derived mitochondrial transcription factor A, and glucose transporter 4. Although GH increased whole-body protein synthesis (nonoxidative disposal of leucine), no effect on synthesis rate of muscle mitochondrial proteins was observed. CONCLUSIONS: These results demonstrate that acute GH action promotes an increase in mitochondrial oxidative capacity and abundance of several mitochondrial genes. These events may occur through direct or indirect effects of GH on intracellular signaling pathways but do not appear to involve a change in mitochondrial protein synthesis rate.

Lack of dehydroepiandrosterone effect on a combined endurance and resistance exercise program in postmenopausal women.

CONTEXT: Recent studies disputed the widely promoted anti-aging effect of dehydroepiandrosterone (DHEA) supplementation; however, conflicting data exist on whether physiological DHEA supplementation enhances exercise training effects on body composition, physical performance, and cardiometabolic risk in healthy postmenopausal women. OBJECTIVE: The aim of this study was to determine whether 12 wk of DHEA supplementation (50 mg/d) in postmenopausal women enhances exercise-related changes in body composition, physical performance, and cardiometabolic risk. DESIGN AND SETTING: This study was a 12-wk randomized double-blind, placebo-controlled trial and took place at the Mayo Clinic General Clinical Research Center (Rochester, MN). PARTICIPANTS: Thirty-one sedentary, postmenopausal, Caucasian women (mean +/- sem age 64.6 +/- 1.0 yr) completed the study. INTERVENTION: Participants were randomized to one of two 12-wk interventions: 1) exercise training plus 50 mg/d of DHEA (n = 17), or 2) exercise training plus placebo (n = 14). The exercise intervention consisted of both endurance (4 d/wk) and resistance (3 d/wk) exercise components. MAIN OUTCOME MEASURES: The main outcomes were measures of body composition, physical performance, and measures of cardiometabolic risk. RESULTS: DHEA treatment with exercise resulted in increases in circulating sulfated DHEA (650%), total testosterone (100%), estradiol (165%), estrone (85%), and IGF-I (30%) (all P < or = 0.05, for all within and between treatment comparisons). Although exercise training alone significantly improved physical performance, body composition, and insulin sensitivity, administration of DHEA provided no additional benefits. CONCLUSIONS: Twelve weeks of combined endurance and resistance training significantly improved body composition, physical performance, insulin sensitivity, and low-density lipoprotein cholesterol particle number and size, whereas DHEA had no additional benefits.

Effect of insulin deprivation on muscle mitochondrial ATP production and gene transcript levels in type 1 diabetic subjects.

OBJECTIVE: Muscle mitochondrial dysfunction occurs in many insulin-resistant states, such as type 2 diabetes, prompting a hypothesis that mitochondrial dysfunction may cause insulin resistance. We determined the impact of insulin deficiency on muscle mitochondrial ATP production by temporarily depriving type 1 diabetic patients of insulin treatment. RESEARCH DESIGN AND METHODS: We withdrew insulin for 8.6 +/- 0.6 h in nine C-peptide-negative type 1 diabetic subjects and measured muscle mitochondrial ATP production and gene transcript levels (gene array and real-time quantitative PCR) and compared with insulin-treated state. We also measured oxygen consumption (indirect calorimetry); plasma levels of glucagon, bicarbonate, and other substrates; and urinary nitrogen. RESULTS: Withdrawal of insulin resulted in increased plasma glucose, branched chain amino acids, nonesterified fatty acids, beta-hydroxybutyrate, and urinary nitrogen but no change in bicarbonate. Insulin deprivation decreased muscle mitochondrial ATP production rate (MAPR) despite an increase in whole-body oxygen consumption and altered expression of many muscle mitochondrial gene transcripts. Transcript levels of genes involved in oxidative phosphorylation were decreased, whereas those involved in vascular endothelial growth factor (VEGF) signaling, inflammation, cytoskeleton signaling, and integrin signaling pathways were increased. CONCLUSIONS: Insulin deficiency and associated metabolic changes reduce muscle MAPR and expression of oxidative phosphorylation genes in type 1 diabetes despite an increase in whole-body oxygen consumption. Increase in transcript levels of genes involved in VEGF, inflammation, cytoskeleton, and integrin signaling pathways suggest that vascular factors and cell proliferation that may interact with mitochondrial changes occurred.

Skeletal muscle mitochondrial functions, mitochondrial DNA copy numbers, and gene transcript profiles in type 2 diabetic and nondiabetic subjects at equal levels of low or high insulin and euglycemia.

We investigated whether previously reported muscle mitochondrial dysfunction and altered gene transcript levels in type 2 diabetes might be secondary to abnormal blood glucose and insulin levels rather than an intrinsic defect of type 2 diabetes. A total of 13 type 2 diabetic and 17 nondiabetic subjects were studied on two separate occasions while maintaining similar insulin and glucose levels in both groups by 7-h infusions of somatostatin, low- or high-dose insulin (0.25 and 1.5 mU/kg of fat-free mass per min, respectively), and glucose. Muscle mitochondrial DNA abundance was not different between type 2 diabetic and nondiabetic subjects at both insulin levels, but the majority of transcripts in muscle that are involved mitochondrial functions were expressed at lower levels in type 2 diabetes at low levels of insulin. However, several gene transcripts that are specifically involved in the electron transport chain were expressed at higher levels in type 2 diabetic patients. After the low-dose insulin infusion, which achieved postabsorptive insulin levels, the muscle mitochondrial ATP production rate (MAPR) was not different between type 2 diabetic and nondiabetic subjects. However, increasing insulin to postprandial levels increased the MAPR in nondiabetic subjects but not in type 2 diabetic patients. The lack of MAPR increment in response to high-dose insulin in type 2 diabetic patients occurred in association with reduced glucose disposal and expression of peroxisome proliferator-activated receptor-gamma coactivator 1alpha, citrate synthase, and cytochrome c oxidase I. In conclusion, the current data supports that muscle mitochondrial dysfunction in type 2 diabetes is not an intrinsic defect, but instead a functional defect related to impaired response to insulin.

Changes in skeletal muscle protein metabolism and myosin heavy chain isoform messenger ribonucleic acid abundance after treatment of hyperthyroidism.

BACKGROUND: Hyperthyroidism causes a hypermetabolic state and skeletal muscle dysfunction, but the underlying mechanism remains incompletely defined. OBJECTIVE: The objective of the study was to determine whether treatment of hyperthyroidism causes changes in amino acid fluxes, synthesis rates of muscle proteins, and expression of muscle myosin heavy chain (MHC) that may impact skeletal muscle function and metabolic rate. METHODS: Eight hyperthyroid patients were studied (TSH 0.008 +/- 0.001 mU/liter) before treatment and at least 9 months after correction of hyperthyroidism (TSH 2.3 +/- 0.4) (P < 0.03). Fluxes of leucine and phenylalanine as well as muscle protein synthesis rates were measured using L[1,2 13C] leucine and L(15N) phenylalanine as tracers. mRNA levels of selected genes were measured in muscle biopsy samples. RESULTS: Treatment decreased resting metabolic rate that paralleled changes in fluxes of leucine and phenylalanine accompanied by improved muscle strength and mass. Synthesis rates of mixed muscle proteins (P = 0.01), sarcoplasmic (P = 0.04), and mitochondrial (P = 0.08) proteins decreased, whereas MHC synthesis was unchanged. Selective increases in mRNA abundance of muscle MHC1 isoform (P = 0.04) and decrease of MHCIIA (P = 0.007) and MHCIIx (P = 024) were observed. Muscle mitochondrial oxidative enzymes and mRNA levels of mitochondrial proteins were unchanged, but uncoupling protein2 and uncoupling protein3 mRNA levels (P = 0.02) decreased. CONCLUSION: Increased amino acid flux, mixed muscle protein synthesis, and synthesis of sarcoplasmic proteins are consistent with the hypermetabolic state in hyperthyroidism. After treatment, MHC synthesis rates were unchanged, but mRNA levels of isoforms of MHC found in slow-twitch and fast-twitch fibers increased and decreased, respectively. These results offer a mechanistic explanation for posttreatment improvement in muscle functions in hyperthyroidism.

Effects of insulin deprivation and treatment on homocysteine metabolism in people with type 1 diabetes.

CONTEXT: Abnormal homocysteine metabolism may contribute to increased cardiovascular death in type 1 diabetes (T1DM). Amino acid metabolism is altered in T1DM. In vitro, insulin reduces hepatic catabolism of homocysteine by inhibiting liver transsulfuration. It remains to be determined whether methionine-homocysteine metabolism is altered in T1DM. OBJECTIVE: We sought to determine whether insulin deficiency during insulin deprivation or high plasma insulin concentration after insulin treatment alters homocysteine metabolism in T1DM. DESIGN: This was an acute interventional study with paired and comparative controls. SETTING: The study was conducted at a general clinical research center. PATIENTS AND INTERVENTION: We used stable isotope tracers to measure methionine-homocysteine kinetics in six patients with T1DM during insulin deprivation (I-) and also during insulin treatment (I+) and compared them with nondiabetic controls (n = 6). MAIN OUTCOME MEASURES: Homocysteine kinetics (transmethylation, transsulfuration, and remethylation) were from plasma isotopic enrichment of methionine and homocysteine and (13)CO(2). RESULTS: T1DM (I-) had lower rates of homocysteine-methionine remethylation (P < 0.05 vs. control and I+). In contrast, transsulfuration rates were higher in I- than controls and I+ (P < 0.05). Insulin treatment normalized transsulfuration and remethylation (P < 0.05 vs. I- and P > 0.8 vs. control). Plasma homocysteine concentrations were lower in T1DM (P < 0.05 vs. control during both I- and I+), which may be explained by increased homocysteine transsulfuration. Thus, significant alterations of methionine-homocysteine metabolism occur during insulin deprivation in humans with T1DM. CONCLUSIONS: Insulin plays a key role in the regulation of methionine-homocysteine metabolism in humans, and altered homocysteine may occur during insulin deficiency in type 1 diabetic patients.

Mechanism of insulin's anabolic effect on muscle: measurements of muscle protein synthesis and breakdown using aminoacyl-tRNA and other surrogate measures.

Despite being an anabolic hormone in skeletal muscle, insulin's anticatabolic mechanism in humans remains controversial, with contradictory reports showing either stimulation of protein synthesis (PS) or inhibition of protein breakdown (PB) by insulin. Earlier measurements of muscle PS and PB in humans have relied on different surrogate measures of aminoacyl-tRNA and intracellular pools. We report that insulin's effect on muscle protein turnover using aminoacyl-tRNA as the precursor of PS and PB is calculated by mass balance of tracee amino acid (AA). We compared the results calculated from various surrogate measures. To determine the physiological role of insulin on muscle protein metabolism, we infused tracers of leucine and phenylalanine into 18 healthy subjects, and after 3 h, 10 subjects received a 4-h femoral arterial infusion of insulin (0.125 mUxkg(-1)xmin(-1)), while eight subjects continued with saline. Tracer-to-tracee ratios of leucine, phenylalanine, and ketoisocaproate were measured in the arterial and venous plasma, muscle tissue fluid, and AA-tRNA to calculate muscle PB and PS. Insulin infusion, unlike saline, significantly reduced the efflux of leucine and phenylalanine from muscle bed, based on various surrogate measures which agreed with those based on leucyl-tRNA (-28%), indicating a reduction in muscle PB (P < 0.02) without any significant effect on muscle PS. In conclusion, using AA-tRNA as the precursor pool, it is demonstrated that, in healthy humans in the postabsorptive state, insulin does not stimulate muscle protein synthesis and confirmed that insulin achieves muscle protein anabolism by inhibition of muscle protein breakdown.

Decline in skeletal muscle mitochondrial function with aging in humans.

Cumulative mtDNA damage occurs in aging animals, and mtDNA mutations are reported to accelerate aging in mice. We determined whether aging results in increased DNA oxidative damage and reduced mtDNA abundance and mitochondrial function in skeletal muscle of human subjects. Studies performed in 146 healthy men and women aged 18-89 yr demonstrated that mtDNA and mRNA abundance and mitochondrial ATP production all declined with advancing age. Abundance of mtDNA was positively related to mitochondrial ATP production rate, which in turn, was closely associated with aerobic capacity and glucose tolerance. The content of several mitochondrial proteins was reduced in older muscles, whereas the level of the oxidative DNA lesion, 8-oxo-deoxyguanosine, was increased, supporting the oxidative damage theory of aging. These results demonstrate that age-related muscle mitochondrial dysfunction is related to reduced mtDNA and muscle functional changes that are common in the elderly.

Effect of dehydroepiandrosterone replacement on insulin sensitivity and lipids in hypoadrenal women.

DHEA (dehydroepiandrosterone) replacement is not part of the current standard of care in hypoadrenal subjects. Animal studies have shown that DHEA administration prevents diabetes. To determine the physiological effect of DHEA replacement on insulin sensitivity in adrenal-deficient women, we performed a single-center, randomized, double-blind, placebo-controlled, crossover study in 28 hypoadrenal women (mean age 50.2 +/- 2.87 years) who received a single 50-mg dose of DHEA daily or placebo. After 12 weeks, insulin sensitivity was assessed using a hyperinsulinemic-euglycemic clamp. DHEA replacement significantly increased DHEA-S (sulfated ester of DHEA), bioavailable testosterone, and androstenedione and reduced sex hormone-binding globulin levels. Fasting plasma insulin and glucagon were lower with DHEA (42 +/- 4.94 vs. 53 +/- 6.58 pmol/l [P = 0.005] and 178 +/- 11.32 vs. 195.04 +/- 15 pmol/l [P = 0.02], respectively). The average amount of glucose needed to maintain similar blood glucose levels while infusing the same insulin dosages was higher during DHEA administration (358 +/- 24.7 vs. 320 +/- 24.6 mg/min; P < 0.05), whereas endogenous glucose production was similar. DHEA also reduced total cholesterol (P < 0.005), triglycerides (P < 0.011), LDL cholesterol (P < 0.05), and HDL cholesterol (P < 0.005). In conclusion, replacement therapy with 50 mg of DHEA for 12 weeks significantly increased insulin sensitivity in hypoadrenal women, thereby suggesting that DHEA replacement could have a potential impact in preventing type 2 diabetes.

Changes in myosin heavy chain mRNA and protein expression in human skeletal muscle with age and endurance exercise training.

Aging is associated with reduced muscle strength and atrophy of type II muscle fibers. Muscle fiber type and contractile function are primarily determined by myosin heavy chain (MHC) isoforms. There are few data available on the effects of aging on MHC isoform expression in humans. In the present study, we tested the hypothesis that MHC isoform protein composition and mRNA abundance would favor a fast-to-slow isoform shift with aging and in response to endurance exercise training. Muscle biopsies were obtained from previously sedentary, healthy men and women, aged 21-87 yr before (n = 77) and after (n = 65) 16 wk of bicycle training (up to 45 min at 80% peak heart rate, 3-4 days/wk). At baseline, MHC I mRNA was unchanged with age, whereas IIa and IIx declined by 14 and 10% per decade, respectively (P < 0.001). MHC IIa and IIx protein declined by 3 and 1% per decade with a reciprocal increase in MHC I (P < 0.05). After training, MHC I and IIa mRNA increased by 61 and 99%, respectively, and IIx decreased by 50% (all P < 0.001). The increase in MHC I mRNA was positively associated with age, whereas the changes in MHC IIa and IIx mRNA were similar across age. MHC I protein increased by 6% and was positively related to age, whereas IIx decreased by 5% and was inversely related to age. These results suggest that the altered expression of MHC isoforms with aging is transcriptionally regulated. In response to endurance exercise, regulation of MHC isoform transcripts remains robust in older muscle, but this did not result in corresponding changes in MHC protein expression.

Effect of short-term prednisone use on blood flow, muscle protein metabolism, and function.

Glucocorticoids can cause muscle atrophy, but the effect on muscle protein metabolism in humans has not been adequately studied to know whether protein synthesis, breakdown, or both are altered. We tested the effect of 6 d of oral prednisone (Pred, 0.5 mg/kg.d) on muscle protein metabolism and function. Six healthy subjects (three men/three women, 22-41 yr) completed two trials (randomized, double-blind, cross-over) with Pred and placebo. Fasting glucose, insulin, IGF-I, and glucagon were higher on Pred vs. placebo, whereas IGF-II and IGF binding protein-1 and -2 were lower. Whole-body amino acid fluxes, blood urea nitrogen, and urinary nitrogen loss were not statistically different between trials. Leg blood flow was 25% lower on Pred leading to 15-30% lower amino acid flux among the artery, vein, and muscle. However, amino acid net balance and rates of protein synthesis and breakdown were unchanged, as were synthesis rates of total mixed, mitochondrial, sarcoplasmic, and myosin heavy chain muscle proteins. Muscle mitochondrial function, muscle strength, and resting energy expenditure were also unchanged. These results demonstrate that a short-term moderate dose of prednisone affects glucose metabolism but has no effect on whole-body or leg muscle protein metabolism or muscle function.