HMB attenuates muscle loss during sustained energy deficit induced by calorie restriction and endurance exercise

OBJECTIVE

To investigate the efficacy and underlying mechanisms of β-hydroxy-β-methylbutyrate (HMB) on body composition, muscle mass and physical performance under catabolic versus normal training conditions.

MATERIALS/METHODS

Mice were divided into four groups (n=10/group): (1) ALT=ad libitum+trained (1 h/d for 3 d/wk); (2) ALTH=ALT+HMB (0.5 g/kg BW/d); (3) C=calorie restricted (-30%)+trained (6 h/d, 6 d/wk); and (4) CH=C+HMB. Repeated in vivo assessments included body composition, grip strength and sensorimotor coordination before and after the experimental protocol, while in vitro analyses included muscle wet weights, expression of selected genes and proteins regulating muscle mass, and myofiber cross-sectional area. ANOVAs were used with significance set at p<0.05.

RESULTS

ALTH had greater lean mass than ALT and sensorimotor function increased in ALTH, but decreased in ALT under normal training conditions. Grip strength decreased only in C, but was maintained in CH. Gastrocnemius mass and myofiber CSA were greater in CH than C following catabolic conditions. Gastrocnemius atrogin-1 mRNA expression was elevated in C but not in CH compared to all other groups whereas atrogin-1 protein levels showed no significant changes.

CONCLUSION

HMB improves body composition and sensorimotor function during normal training and attenuates muscle mass and strength loss during catabolic conditions.

Glial cell line-derived neurotrophic factor (GDNF) expression and NMJ plasticity in skeletal muscle following endurance exercise

Glial cell line-derived neurotrophic factor (GDNF) supports and maintains the neuromuscular system during development and through adulthood by promoting neuroplasticity. The aim of this study was to determine if different modes of exercise can promote changes in GDNF expression and neuromuscular junction (NMJ) morphology in slow- and fast-twitch muscles. Rats were randomly assigned to a run training (run group), swim training (swim group), or sedentary control group. GDNF protein content was determined by enzyme-linked immunosorbant assay. GDNF protein content increased significantly in soleus (SOL) following both training protocols (P<0.05). Although not significant, an increase of 60% in the extensor digitorum longus (EDL) followed swim-training (NS; P<0.06). NMJ morphology was analyzed by measuring α-bungarotoxin labeled post-synaptic end plates. GDNF content and total end plate area were positively correlated. End plate area decreased in EDL of the run group and increased in SOL of the swim group. The results indicate that GDNF expression and NMJ morphological changes are activity dependent and that different changes may be observed by varying the exercise intensity in slow- and fast-twitch fibers.

Cortical folding is altered before surgery in infants with congenital heart disease

Infants with congenital heart disease have altered brain development. We characterized cortical folding, a critical part of brain development, in congenital heart disease infants and demonstrated an overall decrease in cortical surface area and cortical folding with regional alterations in the right lateral sulcus and left orbitofrontal region, cingulate region, and central sulcus. These abnormalities were present prior to surgery.

The relationship between anti-idursulfase antibody status and safety and efficacy outcomes in attenuated mucopolysaccharidosis II patients aged 5 years and older treated with intravenous idursulfase

In the pivotal phase II/III trial of idursulfase administered intravenously to treat mucopolysaccharidosis II, approximately half of the patients developed antibodies to idursulfase. This post-hoc analysis of data from the phase II/III trial and extension study examined the relationship between antibody status and outcomes. A total of 63 treatment-naïve patients received 0.5 mg/kg of intravenous idursulfase weekly for two years. Thirty-two patients (51%) were positive for anti-idursulfase IgG antibodies, 23 of whom (37%) became persistently positive. All patients who developed an antibody response did so by their scheduled Week 27 study visit. Positive antibody status appeared to have no statistically significant effect upon changes in six-minute walk test distance, percent predicted forced vital capacity, or liver and spleen volume. All patients showed significant decreases in urinary GAG levels, although the antibody positive group maintained somewhat higher urinary GAG levels than their antibody-negative counterparts at the end of study (138.7 vs. 94.7 μg/mg creatinine, p = 0.001). Antibody positivity was not associated with a higher event rate for serious adverse events. Among patients who had no prior infusion-related reactions, antibody positive patients were 2.3 times more likely to have a first infusion-related reaction than those who would remain negative (p = 0.017); the risk increased to 2.5 times more likely for those who were persistently positive (p = 0.009). These differences in risk disappeared among patients with a previous infusion-related reaction, likely because of preventive measures. A genotype analysis for the 36 patients with available data found that patients with nonsense or frameshift mutations may be more likely to develop antibodies, to experience infusion-related reactions, and to have a reduced uGAG response than those with missense mutations, suggesting the possibility that antibodies are not a driver of clinical outcomes but rather a marker for genotype.

Sensitivity and resolution enhancement of oriented solid-state NMR: application to membrane proteins

Oriented solid-state NMR (O-ssNMR) spectroscopy is a major technique for the high-resolution analysis of the structure and topology of transmembrane proteins in native-like environments. Unlike magic angle spinning (MAS) techniques, O-ssNMR spectroscopy requires membrane protein preparations that are uniformly oriented (mechanically or magnetically) so that anisotropic NMR parameters, such as dipolar and chemical shift interactions, can be measured to determine structure and orientation of membrane proteins in lipid bilayers. Traditional sample preparations involving mechanically aligned lipids often result in short relaxation times which broaden the (15)N resonances and encumber the manipulation of nuclear spin coherences. The introduction of lipid bicelles as membrane mimicking systems has changed this scenario, and the more favorable relaxation properties of membrane protein (15)N and (13)C resonances make it possible to develop new, more elaborate pulse sequences for higher spectral resolution and sensitivity. Here, we describe our recent progress in the optimization of O-ssNMR pulse sequences. We explain the theory behind these experiments, demonstrate their application to small and medium size proteins, and describe the technical details for setting up these new experiments on the new generation of NMR spectrometers.

Cyclic nucleotide phosphodiesterase 3A1 protects the heart against ischemia-reperfusion injury

Phosphodiesterase 3A (PDE3A) is a major regulator of cAMP in cardiomyocytes. PDE3 inhibitors are used for acute treatment of congestive heart failure, but are associated with increased incidence of arrhythmias and sudden death with long-term use. We previously reported that chronic PDE3A downregulation or inhibition induced myocyte apoptosis in vitro. However, the cardiac protective effect of PDE3A has not been demonstrated in vivo in disease models. In this study, we examined the role of PDE3A in regulating myocardial function and survival in vivo using genetically engineered transgenic mice with myocardial overexpression of the PDE3A1 isozyme (TG). TG mice have reduced cardiac function characterized by reduced heart rate and ejection fraction (52.5±7.8% vs. 83.9±4.7%) as well as compensatory expansion of left ventricular diameter (4.19±0.19mm vs. 3.10±0.18mm). However, there was no maladaptive increase of fibrosis and apoptosis in TG hearts compared to wild type (WT) hearts, and the survival rates also remained the same. The diminution of cardiac contractile function is very likely attributed to a decrease in beta-adrenergic receptor (β-AR) response in TG mice. Importantly, the myocardial infarct size (4.0±1.8% vs. 24.6±3.8%) and apoptotic cell number (1.3±1.0% vs. 5.6±1.5%) induced by ischemia/reperfusion (I/R) injury were significantly attenuated in TG mice. This was associated with decreased expression of inducible cAMP early repressor (ICER) and increased expression of anti-apoptotic protein BCL-2. To further verify the anti-apoptotic effects of PDE3A1, we performed in vitro apoptosis study in isolated adult TG and WT cardiomyocytes. We found that the apoptotic rates stimulated by hypoxia/reoxygenation or H2O2 were indeed significantly reduced in TG myocytes, and the differences between TG and WT myocytes were completely reversed in the presence of the PDE3 inhibitor milrinone. These together indicate that PDE3A1 negatively regulates β-AR signaling and protects against I/R injury by inhibiting cardiomyocyte apoptosis.

OGT and OGA expression in postmenopausal skeletal muscle associates with hormone replacement therapy and muscle cross-sectional area

Protein glycosylation via O-linked N-acetylglucosaminylation (O-GlcNAcylation) is an important post-translational regulatory mechanism mediated by O-GlcNAc transferase (OGT) and responsive to nutrients and stress. OGT attaches an O-GlcNAc moiety to proteins, while O-GlcNAcase (OGA) catalyzes O-GlcNAc removal. In skeletal muscle of experimental animals, prolonged increase in O-GlcNAcylation associates with age and muscle atrophy. Here we examined the effects of hormone replacement therapy (HRT) and power training (PT) on muscle OGT and OGA gene expression in postmenopausal women generally prone to age-related muscle weakness. In addition, the associations of OGT and OGA gene expressions with muscle phenotype were analyzed. Twenty-seven 50-57-year-old women participated in a yearlong randomized placebo-controlled trial: HRT (n=10), PT (n=8) and control (n=9). OGT and OGA mRNA levels were measured from muscle samples obtained at baseline and after one year. Knee extensor muscle cross-sectional area (CSA), knee extension force, running speed and vertical jumping height were measured. During the yearlong intervention, HRT suppressed the aging-associated upregulation of OGT mRNA that occurred in the controls. The effects of PT were similar but weaker. HRT also tended to increase the OGA mRNA level compared to the controls. The change in the ratio of OGT to OGA gene expressions correlated negatively with the change in muscle CSA. Our results suggest that OGT and OGA gene expressions are associated with muscle size during the critical postmenopausal period. HRT and PT influence muscle OGT and OGA gene expression, which may be one of the mechanisms by which HRT and PT prevent aging-related loss of muscle mass.

Investigating the interaction between peptides of the amphipathic helix of Hcf106 and the phospholipid bilayer by solid-state NMR spectroscopy

The chloroplast twin arginine translocation (cpTat) system transports highly folded precursor proteins into the thylakoid lumen using the protonmotive force as its only energy source. Hcf106, as one of the core components of the cpTat system, is part of the precursor receptor complex and functions in the initial precursor-binding step. Hcf106 is predicted to contain a single amino terminal transmembrane domain followed by a Pro-Gly hinge, a predicted amphipathic α-helix (APH), and a loosely structured carboxy terminus. Hcf106 has been shown biochemically to insert spontaneously into thylakoid membranes. To better understand the membrane active capabilities of Hcf106, we used solid-state NMR spectroscopy to investigate those properties of the APH. In this study, synthesized peptides of the predicted Hcf106 APH (amino acids 28-65) were incorporated at increasing mol.% into 1-palmitoyl-2-oleoyl-sn-glycero-phosphocholine (POPC) and POPC/MGDG (monogalactosyldiacylglycerol; mole ratio 85:15) multilamellar vesicles (MLVs) to probe the peptide-lipid interaction. Solid-state (31)P NMR and (2)H NMR spectroscopic experiments revealed that the peptide perturbs the headgroup and the acyl chain regions of phospholipids as indicated by changes in spectral lineshape, chemical shift anisotropy (CSA) line width, and (2)H order SCD parameters. In addition, the comparison between POPC MLVs and POPC/MGDG MLVs indicated that the lipid bilayer composition affected peptide perturbation of the lipids, and such perturbation appeared to be more intense in a system more closely mimicking a thylakoid membrane.

Criteria to average out the chemical shift anisotropy in solid-state NMR when irradiated with BABA I, BABA II, and C7 radiofrequency pulse sequences

Floquet-Magnus expansion is used to study the effect of chemical shift anisotropy in solid-state NMR of rotating solids. The chemical shift interaction is irradiated with two types of radiofrequency pulse sequences: BABA and C7. The criteria for the chemical shift anisotropy to be averaged out in each rotor period are obtained.

A clinical prediction model to estimate the risk for coarctation of the aorta in the presence of a patent ductus arteriosus

BACKGROUND

Diagnosing coarctation of the aorta (CoA) in the presence of a patent ductus arteriosus (PDA) may require observation until PDA closure. The aim of this study was to create a model incorporating previously published indices to estimate the probability of neonatal CoA in the presence of a PDA.

METHODS

A retrospective "investigation" cohort of 80 neonates was divided into two groups: (1) neonates with PDA and suspicion for CoA requiring observation to confirm the presence or absence of CoA and (2) neonates with PDA and confirmed diagnosis of either CoA or unobstructed aortic arch. Multivariate logistic regression was used to create the coarctation probability model (CPM), which was used to calculate a neonate's probability of CoA. The CPM was validated internally using bootstrapping and subsequently validated prospectively using a "validation" cohort of 74 neonates with PDA.

RESULTS

The CPM had an area under the receiver operating characteristic curve of 0.96 and demonstrated good clinical significance in the risk stratification of neonates with PDA and CoA. No neonate with a CPM probability of <15% had CoA after PDA closure. Neonates with CPM probability < 15% were classified at low risk, between 15% and 60% at moderate risk, and >60% at high risk for CoA.

CONCLUSIONS

On the basis of these results, the authors recommend measurement of the CPM in all neonates with PDA. Those with CPM probability < 15% no longer require observation, which could decrease observation in as many as half of neonates with unobstructed aortic arches; those with CPM probabilities between 15% and 60% require follow-up imaging, while those with CPM probabilities > 60% should be observed as inpatients until PDA closure.

Body composition and reproductive function exert unique influences on indices of bone health in exercising women

Reproductive function, metabolic hormones, and lean mass have been observed to influence bone metabolism and bone mass. It is unclear, however, if reproductive, metabolic and body composition factors play unique roles in the clinical measures of areal bone mineral density (aBMD) and bone geometry in exercising women. This study compares lumbar spine bone mineral apparent density (BMAD) and estimates of femoral neck cross-sectional moment of inertia (CSMI) and cross-sectional area (CSA) between exercising ovulatory (Ov) and amenorrheic (Amen) women. It also explores the respective roles of reproductive function, metabolic status, and body composition on aBMD, lumbar spine BMAD and femoral neck CSMI and CSA, which are surrogate measures of bone strength. Among exercising women aged 18-30 years, body composition, aBMD, and estimates of femoral neck CSMI and CSA were assessed by dual-energy x-ray absorptiometry. Lumbar spine BMAD was calculated from bone mineral content and area. Estrone-1-glucuronide (E1G) and pregnanediol glucuronide were measured in daily urine samples collected for one cycle or monitoring period. Fasting blood samples were collected for measurement of leptin and total triiodothyronine. Ov (n = 37) and Amen (n = 45) women aged 22.3 ± 0.5 years did not differ in body mass, body mass index, and lean mass; however, Ov women had significantly higher percent body fat than Amen women. Lumbar spine aBMD and BMAD were significantly lower in Amen women compared to Ov women (p < 0.001); however, femoral neck CSA and CSMI were not different between groups. E1G cycle mean and age of menarche were the strongest predictors of lumbar spine aBMD and BMAD, together explaining 25.5% and 22.7% of the variance, respectively. Lean mass was the strongest predictor of total hip and femoral neck aBMD as well as femoral neck CSMI and CSA, explaining 8.5-34.8% of the variance. Upon consideration of several potential osteogenic stimuli, reproductive function appears to play a key role in bone mass at a site composed of primarily trabecular bone. However, lean mass is one of the most influential predictors of bone mass and bone geometry at weight-bearing sites, such as the hip.

Esophageal distensibility as a measure of disease severity in patients with eosinophilic esophagitis

BACKGROUND & AIMS

The aim of this study was to assess whether measurements of esophageal distensibility, made by high-resolution impedance planimetry, correlated with important clinical outcomes in patients with eosinophilic esophagitis.

METHODS

Seventy patients with eosinophilic esophagitis (50 men; age, 18-68 y) underwent endoscopy with esophageal biopsy collection and high-resolution impedance planimetry using the functional lumen-imaging probe. The patients were followed up prospectively for an average of 9.2 months (range, 3-14 mo), and the risk of food impaction, requirement for dilation, and symptom severity during the follow-up period was determined from medical records. Esophageal distensibility metrics and the severity of mucosal eosinophilia at baseline were compared between patients presenting with and without food impaction and those requiring or not requiring esophageal dilation. Logistic regression and stratification assessments were used to assess the predictive value of esophageal distensibility metrics in assessing risk of food impaction, the need for dilation, and continued symptoms.

RESULTS

Patients with prior food impactions had significantly lower distensibility plateau (DP) values than those with solid food dysphagia alone. In addition, patients sustaining food impaction and requiring esophageal dilation during the follow-up period had significantly lower DP values than those who did not. The severity of mucosal eosinophilia did not correlate with risk for food impaction, the requirement for dilation during follow-up evaluation, or DP values.

CONCLUSIONS

Reduced esophageal distensibility predicts risk for food impaction and the requirement for esophageal dilation in patients with eosinophilic esophagitis. The severity of mucosal eosinophilia was not predictive of these outcomes and had a poor correlation with esophageal distensibility.

Differential adhesion-inhibitory patterns of antibodies raised against two major variants of the NTS-DBL2X region of VAR2CSA

BACKGROUND

VAR2CSA is a large polymorphic Plasmodium falciparum protein expressed on infected erythrocytes (IE) that allows their binding in the placenta, thus precipitating placental malaria (PM). The N-terminal part of VAR2CSA that contains the binding site to placental chondroitin sulfate A (CSA) is currently recognized as the most attractive region for vaccine development. An ultimate challenge is to define epitopes in this region that induce a broad cross-reactive adhesion inhibitory antibody response.

METHODS

Based on phylogenetic data that identified a dimorphic sequence motif in the VAR2CSA DBL2X, we raised antibodies against the NTS-DBL2X constructs containing one sequence or the other (3D7 and FCR3) and tested their functional properties on P. falciparum isolates from pregnant women and on laboratory-adapted strains.

RESULTS

The CSA binding inhibitory capacity of the antibodies induced varied from one parasite isolate to another (range, 10%–100%), but the combined analysis of individual activity highlighted a broader functionality that increased the total number of isolates inhibited. Interestingly, the differential inhibitory effect of the antibodies observed on field isolates resulted in significant inhibition of all field isolates tested, suggesting that optimal inhibitory spectrum on field isolates from pregnant women might be achieved with antibodies targeting limited variants of the N-terminal VAR2CSA.

CONCLUSIONS

Our findings indicate that the NTS-DBL2X region of VAR2CSA can elicit strain-transcending anti-adhesion antibodies and suggest that the combination of the two major variants used here could represent the basis for an effective bivalent VAR2CSA-based vaccine.

Association of high post-transplant soluble CD30 serum levels with chronic allograft nephropathy

The purpose of this study was to evaluate the association of post-transplant soluble CD30 (sCD30) levels, isolated or in combination with of anti-HLA class II antibodies and of serum creatinine levels, with kidney graft loss due to chronic allograft nephropathy (CAN), and type of lesions in graft biopsies for cause. The study comprised 511 first kidney graft recipients, transplanted at a single center, with a graft functioning for at least 2.8 years. A single blood sample was collected from each patient. sCD30 levels were determined by ELISA, and HLA antibodies by Luminex assay. The minimum follow-up after testing was 9.3 years. High sCD30 levels, set at sCD30 ≥ 34.15 ng/mL, the presence of HLA class II antibodies, and serum creatinine ≥ 1.9 mg/dL were independently associated with CAN-graft loss (P values <0.0001, 0.05, <0.0001, respectively), and the combined hazard ratio for CAN-graft loss was 20.2. Analyses of 166 biopsies for cause showed that high sCD30 levels and creatinine were independently associated with interstitial lesions. Post-transplant sCD30 serum levels, especially in conjunction with information regarding HLA class II antibodies and serum creatinine levels, provide valuable information regarding graft outcome and could be useful for the management of kidney transplant recipients.

Peripubertal female athletes in high-impact sports show improved bone mass acquisition and bone geometry

OBJECTIVE

Intensive physical training may have a sport-dependent effect on bone mass acquisition. This cross-sectional study evaluated bone mass acquisition in girls practicing sports that put different mechanical loads on bone.

MATERIALS/METHODS

Eighty girls from 10.7 to 18.0 years old (mean 13.83 ± 1.97) were recruited: 20 artistic gymnasts (AG; high-impact activity), 20 rhythmic gymnasts (RG; medium-impact activity), 20 swimmers (SW, no-impact activity), and 20 age-matched controls (CON; leisure physical activity <3h/wk). Areal bone mineral density (aBMD) was determined using DEXA. Hip structural analysis applied at the femur evaluated cross-sectional area (CSA, cm(2)), section modulus (Z, cm(3)), and buckling ratio. Bone turnover markers and OPG/RANKL levels were analyzed.

RESULTS

AG had higher aBMD than SW and CON at all bone sites and higher values than RG in the lumbar spine and radius. RG had higher aBMD than SW and CON only in the femoral region. CSA and mean cortical thickness were significantly higher and the buckling ratio was significantly lower in both gymnast groups compared with SW and CON. In RG only, endocortical diameter and width were reduced, while Z was only increased in AG compared with SW and CON. Reduced bone remodeling was observed in RG compared with AG only when groups were subdivided according to menarcheal status. All groups showed similar OPG concentrations, while RANKL concentrations increased with age and were decreased in SW.

CONCLUSION

High-impact activity clearly had a favorable effect on aBMD and bone geometry during the growth period, although the bone health benefits seem to be more marked after menarche.

XIAP and P-glycoprotein co-expression is related to imatinib resistance in chronic myeloid leukemia cells

P-glycoprotein (Pgp) and XIAP co-expression has been discussed in the process of the acquisition of multidrug resistance (MDR) in cancer. Here, we evaluated XIAP and Pgp expression in chronic myeloid leukemia (CML) samples, showing a positive correlation between them. Furthermore, we evaluated the effects of imatinib in XIAP and Pgp expression using CML cell lines K562 (Pgp(-)) and K562-Lucena (Pgp(+)). Imatinib increased XIAP and Pgp expression in K562-Lucena cells, while in K562 cells a downregulation of these proteins was observed, suggesting that imatinib induces an increment of MDR phenotype of CML cells that previously exhibit high levels of Pgp/XIAP co-expression.

The N-BAR domain protein, Bin3, regulates Rac1- and Cdc42-dependent processes in myogenesis

Actin dynamics are necessary at multiple steps in the formation of multinucleated muscle cells. BAR domain proteins can regulate actin dynamics in several cell types, but have been little studied in skeletal muscle. Here, we identify novel functions for the N-BAR domain protein, Bridging integrator 3 (Bin3), during myogenesis in mice. Bin3 plays an important role in regulating myofiber size in vitro and in vivo. During early myogenesis, Bin3 promotes migration of differentiated muscle cells, where it colocalizes with F-actin in lamellipodia. In addition, Bin3 forms a complex with Rac1 and Cdc42, Rho GTPases involved in actin polymerization, which are known to be essential for myotube formation. Importantly, a Bin3-dependent pathway is a major regulator of Rac1 and Cdc42 activity in differentiated muscle cells. Overall, these data classify N-BAR domain proteins as novel regulators of actin-dependent processes in myogenesis, and further implicate BAR domain proteins in muscle growth and repair.

A comparative study of magnetic resonance venography techniques for the evaluation of the internal jugular veins in multiple sclerosis patients

BACKGROUND AND PURPOSE

The use of magnetic resonance imaging (MRI) to assess the vascular nature of diseases such as multiple sclerosis (MS) is a growing field of research. This work reports on the application of MR angiographic (MRA) and venographic (MRV) techniques in assessing the extracranial vasculature in MS patients.

MATERIALS AND METHODS

A standardized MRI protocol containing 2D TOF-MRV and dynamic 3D contrast-enhanced (CE) MRAV was run for 170 MS patients and 40 healthy controls (HC). The cross-sectional area (CSA) of the internal jugular veins (IJVs) was measured at three neck levels in all subjects for both MRV techniques to determine the presence of venous stenoses. All data were analyzed retrospectively.

RESULTS

For the values where both methods showed signal, the 3D method showed larger CSA measurement values compared to 2D methods in both IJVs, in both MS and HC subjects which was confirmed with student paired t-tests. Of the 170 MS patients, 93 (55%) in CE-MRAV and 103 (61%) in TOF-MRV showed stenosis in at least one IJV. The corresponding numbers for the 40 HC subjects were 2 (5%) and 4 (10%), respectively. Carotid ectasias with IJV stenosis were seen in 26 cases (15%) with 3D CE-MRAV and were not observable with 2D TOF-MRV. Carotid ectasias were not seen in the HC group. In the 2D TOF-MRV data, banding of the IJVs related to slow flow was seen in 58 (34%) MS cases and in no HC cases. MS patients showed lower average CSAs than the HC subjects.

CONCLUSION

The 3D CE MRAV depicted the vascular anatomy more completely than the 2D TOF-MRV. However, the 3D CE MRAV does not provide any information about the flow characteristics which are indirectly available in the 2D TOF-MRV in those cases where there is slow flow.

Mitochondrial dysfunction and sarcopenia of aging: from signaling pathways to clinical trials

Sarcopenia, the age-related loss of muscle mass and function, imposes a dramatic burden on individuals and society. The development of preventive and therapeutic strategies against sarcopenia is therefore perceived as an urgent need by health professionals and has instigated intensive research on the pathophysiology of this syndrome. The pathogenesis of sarcopenia is multifaceted and encompasses lifestyle habits, systemic factors (e.g., chronic inflammation and hormonal alterations), local environment perturbations (e.g., vascular dysfunction), and intramuscular specific processes. In this scenario, derangements in skeletal myocyte mitochondrial function are recognized as major factors contributing to the age-dependent muscle degeneration. In this review, we summarize prominent findings and controversial issues on the contribution of specific mitochondrial processes - including oxidative stress, quality control mechanisms and apoptotic signaling - on the development of sarcopenia. Extramuscular alterations accompanying the aging process with a potential impact on myocyte mitochondrial function are also discussed. We conclude with presenting methodological and safety considerations for the design of clinical trials targeting mitochondrial dysfunction to treat sarcopenia. Special emphasis is placed on the importance of monitoring the effects of an intervention on muscle mitochondrial function and identifying the optimal target population for the trial. This article is part of a Directed Issue entitled: Molecular basis of muscle wasting.

Progress in spin dynamics solid-state nuclear magnetic resonance with the application of Floquet-Magnus expansion to chemical shift anisotropy

The purpose of this article is to present an historical overview of theoretical approaches used for describing spin dynamics under static or rotating experiments in solid state nuclear magnetic resonance. The article gives a brief historical overview for major theories in nuclear magnetic resonance and the promising theories. We present the first application of Floquet-Magnus expansion to chemical shift anisotropy when irradiated by BABA pulse sequence.

Muscle wasting in cancer

Skeletal muscle loss appears to be the most significant clinical event in cancer cachexia and is associated with a poor outcome. With regard to such muscle loss, despite extensive study in a range of models, there is ongoing debate as to whether a reduction in protein synthesis, an increase in degradation or a combination of both is the more relevant. Each model differs in terms of key mediators and the pathways activated in skeletal muscle. Certain models do suggest that decreased synthesis accompanied by enhanced protein degradation via the ubiquitin proteasome pathway (UPP) is important. Murine models tend to involve rapid development of cachexia and may represent more acute muscle atrophy rather than the chronic wasting observed in humans. There is a paucity of human data both at a basic descriptive level and at a molecular/mechanism level. Progress in treating the human form of cancer cachexia can only move forwards through carefully designed large randomised controlled clinical trials of specific therapies with validated biomarkers of relevance to underlying mechanisms. This article is part of a Directed Issue entitled: Molecular basis of muscle wasting.

Comparison of proximal and distal cross-sectional areas of the median nerve, carpal tunnel, and nerve/tunnel index in subjects with carpal tunnel syndrome

OBJECTIVES

To provide a quantitative analysis of ultrasonographic measurements and possible pathophysiology of carpal tunnel syndrome by comparing cross-sectional areas of the median nerve, carpal tunnel, and nerve/tunnel index and the difference in ultrasonographic findings between affected and nonaffected hands and between sexes.

DESIGN

Blinded comparison study.

SETTING

Secondary referral and training hospital of institutional practice.

PARTICIPANTS

Patients (N=51; 42 women, 9 men) with suspected carpal tunnel syndrome who underwent sonography within 1 week after the electrodiagnostic study.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Electrodiagnostic and ultrasonographic studies were conducted on both upper extremities. Cross-sectional areas of the median nerve and carpal tunnel were measured at 2 separate levels; proximal and distal cross-sectional areas of the carpal tunnel were each measured at the scaphoid-pisiform and trapezium-hamate levels, respectively.

RESULTS

Comparison between normative (n=24) and abnormal hands (n=78) revealed the following: the mean proximal cross-sectional areas of the median nerve, carpal tunnel, and nerve/tunnel index of electrodiagnostically normative hands were 10.941mm(2), 192.43mm(2), and 5.635%, respectively, whereas those of abnormal hands were 13.74mm(2), 208.87mm(2), and 6.693%, respectively, showing statistically significant differences for all (P<.05). Distal measurements of the cross-sectional area of the median nerve, carpal tunnel, and nerve/tunnel index were 10.088mm(2), 150.4mm(2), and 6.762%, respectively, in normative hands, and 11.178mm(2), 149.6mm(2), and 7.493%, respectively, in abnormal hands, showing no statistically significant differences (P>.05). In women, proximal cross-sectional areas of the median nerve and nerve/tunnel index of abnormal hands showed statistically significant differences, but no ultrasonographic measurement with a statistically significant difference was observed in men.

CONCLUSIONS

Compared with nonaffected hands, the proximal cross-sectional areas of the median nerve and carpal tunnel were greater, but the distal ultrasonographic measurements were not in affected hands. Ultrasonographic findings of carpal tunnel syndrome were different according to sex.

Role of a quality management system in improving patient safety - laboratory aspects

OBJECTIVES

The aim of this study is to describe how implementation of a quality management system (QMS) based on ISO 15189 enhances patient safety.

DESIGN AND METHODS

A literature review showed that several European hospitals implemented a QMS based on ISO 9001 and assessed the impact on patient safety. An Internet search showed that problems affecting patient safety have occurred in a number of laboratories across Canada. The requirements of a QMS based on ISO 15189 are outlined, and the impact of the implementation of each requirement on patient safety is summarized. The Quality Management Program - Laboratory Services in Ontario is briefly described, and the experience of Ontario laboratories with Ontario Laboratory Accreditation, based on ISO 15189, is outlined.

RESULTS

Several hospitals that implemented ISO 9001 reported either a positive impact or no impact on patient safety. Patient safety problems in Canadian laboratories are described. Implementation of each requirement of the QMS can be seen to have a positive effect on patient safety. Average laboratory conformance on Ontario Laboratory Accreditation is very high, and laboratories must address and resolve any nonconformities. Other standards, practices, and quality requirements may also contribute to patient safety.

CONCLUSION

Implementation of a QMS based on ISO 15189 provides a solid foundation for quality in the laboratory and enhances patient safety. It helps to prevent patient safety issues; when such issues do occur, effective processes are in place for investigation and resolution. Patient safety problems in Canadian laboratories might have been prevented had effective QMSs been in place. Ontario Laboratory Accreditation has had a positive impact on quality in Ontario laboratories.