Greater Cross-sectional Area Research Articles

Ginger Supplementation Attenuated Mitochondrial Fusion and Improved Skeletal Muscle Size in Type 2 Diabetic Rats.

Oxidative stress, regulated by SOD2 and mitochondrial dynamics, contributes to muscle atrophy in diabetes. Ginger root extract (GRE) reduces oxidative stress. However, its effect on oxidative stress, mitochondrial dynamics, and muscle atrophy is not known in the diabetic muscle. This study examined the effect of GRE on intramuscular oxidative stress, mitochondrial dynamics, and muscle size in diabetic rats. Twenty-six male Sprague-Dawley rats were randomly divided into control diet (CON; n=10), high-fat diet with one dose of 35 mg/kg streptozotocin (HFD; n=9), and high-fat diet with one dose of 35 mg/kg streptozotocin and 0.75% w/w GRE (GRE; n=7) fed for seven weeks. Subsequently, the muscle was analyzed for cross-sectional area (CSA), H2O2 concentration, and DRP-1, MFN2, Parkin, PINK1, SOD2 mRNA. Additionally, the protein levels of SOD2, DRP-1, DRP-1ser616, LC3AB, MFN2, OPA1, Parkin, and PINK1 were analyzed. CSA, H2O2 concentration, and gene and protein expression levels were analyzed using a one-way ANOVA. Correlations among intramuscular H2O2, CSA, and SOD2 protein were assessed using Pearson's bivariate correlation test. In the soleus, the GRE group had a greater CSA and lower intramuscular H2O2 concentration compared to the HFD group. Compared to the HFD group, the GRE group had higher SOD2 and DRP-1 mRNA levels and lower MFN2 and total OPA1 protein levels. H2O2 concentration was negatively correlated with CSA and positively correlated with SOD2. GRE attenuated intramuscular H2O2, mitochondrial fusion, and muscle size loss. These findings suggest that GRE supplementation in diabetic rats reduces oxidative stress, which may contribute to muscle size preservation.

Peripheral Nerve Ultrasound for the Differentiation between ALS, Inflammatory, and Hereditary Polyneuropathies.

Background and Objectives: Ultrasound (US) is a non-invasive tool for the in vivo detection of peripheral nerve alterations. Materials and Methods: In this study, we applied nerve US to assist the discrimination between the spectrum of amyotrophic lateral sclerosis (ALS, n = 11), chronic inflammatory demyelinating polyradiculoneuropathy (CIDP, n = 5), and genetically confirmed Charcot-Marie-Tooth disease (CMT, n = 5). All participants and n = 15 controls without neurological diseases underwent high-resolution US of the bilateral tibial nerve. The nerve cross-sectional area (CSA) and nerve microvascular blood flow were compared between the groups and related to cerebrospinal fluid (CSF) measures, clinical symptoms, and nerve conduction studies. The analyses are part of a larger multimodal study on the comparison between US and 7 Tesla (7T) magnetic resonance neurography (MRN). Results: The patients and controls were matched with respect to their demographical data. CMT had the longest disease duration, followed by CIDP and ALS. CSA was related to age, weight, and disease duration. CSA was larger in CMT and CIDP compared to ALS and controls. The blood flow was greatest in CIDP, and higher than in CMT, ALS, and controls. In ALS, greater CSA was correlated with greater CSF total protein and higher albumin quotient. The US measures did not correlate with clinical scores or nerve conduction studies in any of the subgroups. Conclusion: Our results point towards the feasibility of CSA and blood flow to discriminate between ALS, CIDP, and CMT, even in groups of small sample size. In ALS, larger CSA could indicate an inflammatory disease subtype characterized by reduced blood-nerve barrier integrity. Our upcoming analysis will focus on the additive value of 7T MRN in combination with US to disentangle the spectrum between more inflammatory or more degenerative disease variants among the disease groups.

Fibers in smaller fascicles have lower activation thresholds with cuff electrodes due to thinner perineurium and smaller cross-sectional area

Objective. In nerve stimulation therapies, fibers in larger fascicles generally have higher activation thresholds, but the mechanisms are not well understood. We implemented and analyzed computational models to uncover the effects of morphological parameters on activation thresholds. Approach. We implemented finite element models of human vagus nerve stimulation to quantify the effects of morphological parameters on thresholds in realistic nerves. We also implemented simplified models to isolate effects of perineurium thickness, endoneurium diameter, fiber diameter, and fascicle location on current density, potential distributions (V e), and activation thresholds across cuff geometries and stimulation waveforms. Using V e from each finite element model, we simulated activation thresholds in biophysical cable models of mammalian axons. Main results. Perineurium thickness increases with fascicle diameter, and both thicker perineurium and larger endoneurial diameter contributed to higher activation thresholds via lower peak and broader longitudinal potentials. Thicker perineurium caused less current to enter the fascicle transversely, decreasing peak V e. Thicker perineurium also inhibited current from leaving the fascicle, causing more constant longitudinal current density, broadening V e. With increasing endoneurial diameter, intrafascicular volume increased faster than surface area, thereby decreasing intrafascicular current density and peak V e. Additionally, larger fascicles have greater cross-sectional area, thereby facilitating longitudinal intrafascicular current flow and broadening V e. A large neighboring fascicle could increase activation thresholds, and for a given fascicle, fiber diameter had the greatest effect on thresholds, followed by fascicle diameter, and lastly, fascicle location within the epineurium. The circumneural cuff elicited robust activation across the nerve, whereas a bipolar transverse cuff with small contacts delivering a pseudo-monophasic waveform enabled more selective activation across fiber diameters and locations. Significance. Our computational studies provide mechanistic understanding of neural responses across relevant morphological parameters of peripheral nerves, thereby informing rational design of effective therapies.

Aligning Exposure Limits for Contact Currents with Exposure Limits for Electric Fields.

The Institute for Electrical and Electronic Engineers (IEEE) and the International Commission on Non-ionizing Radiation Protection (ICNIRP) have established limits for exposures to electromagnetic fields across the 0-300 GHz (non-ionizing) spectrum, including limits on contact currents ( CC ) specified by IEEE for 0-110 MHz (ICNIRP issued a CC "guidance level"). Both sets of limits seek to protect against potentially adverse effects, including aversive electrostimulation at frequencies <100 kHz and excessive heating of tissue at frequencies >100 kHz. For the most part, CC is linked to electric field ( E -field) exposures for an ungrounded person contacting a grounded object, with the short-circuit current ( I SC ) through the contact point (usually the hand) equivalent to the current through the grounded feet of a free-standing person exposed to a vertically polarized E -field. The physical linkage between these two quantities dictates that their respective exposure limits align with one another, which is presently not the case, especially with respect to frequencies from100 kHz to 110 MHz. Here we focus specifically on recommendations for revisions to the IEEE standard, IEEE Std C95.1™-2019 ("IEEE C95.1"), in which the E -field exposure limit ( E -field exposure reference levels, ERL s) >100 kHz induces substantially greater currents than the CC ERL s currently prescribed. The most important scenario deserving of attention concerns finger contact through a 1-cm 2 cross-sectional interface between the skin and a grounded conductor in which the rate of temperature rise in the presence of an E -field ERL can be rapid enough to cause a burn injury. This rate is highly dependent on the moistness/dryness of the skin at the contact point (i.e., its impedance)-a highly variable value-with temperature increasing more rapidly with increasing dryness (greater contact impedance). The two main remedies to alleviate the possibility of injury in this "touch" scenario are to (a) limit the time of finger contact to 1 s in all cases and (b) revise the E -field ERL between 100 kHz and 30 MHz from a "hockey-stick-shaped" curve vs. frequency to a "ramp" across this frequency range. These measures factored in with the real-world prevalence of potentially hazardous scenarios should afford greater protection against adverse outcomes than is presently the case. IEEE C95.1 also specifies limits for grasp contact (15 cm 2 in the palm) and associated wrist heating, plus heating in the ankles from free-standing induction. However, these scenarios are more manageable compared to finger touch due mainly to the comparatively lower rates of tissue heating attributable to the wrist's and ankle's relatively greater cross-sectional area. Recommendations for grasp can thus be dealt with separately. Two identified but unaddressed issues in IEEE C95.1 deserving of further attention are first, the circumstance in which a grounded person contacts an ungrounded object situated in an electric field for which there are countless numbers of scenarios that are not amenable to a single ERL . Second, arcing between an extended limb and E -field-exposed object is perhaps the most hazardous of all scenarios. Both of these scenarios cannot be stereotyped and must be dealt with on a case-by-case basis. Future revisions of IEEE Std C95.1-2019 (and the ICNIRP guidelines) will benefit from improved insight into strategies of affording protection from potentially adverse effects in these circumstances.

Challenging the Perceptions of Human Tendon Allografts: Influence of Donor Age, Sex, Height, and Tendon on Biomechanical Properties

Background: The use of allograft tendons has increased for primary and revision anterior cruciate ligament reconstruction, but allograft supply is currently limited to a narrow range of tendons and donors up to the age of 65 years. Expanding the range of donors and tendons could help offset an increasing clinical demand. Purpose: To investigate the effects of donor age, sex, height, and specific tendon on the mechanical properties of a range of human lower leg tendons. Study Design: Descriptive laboratory study. Methods: Nine tendons were retrieved from 39 fresh-frozen human cadaveric lower legs (35 donors [13 female, 22 male]; age, 49-99 years; height, 57-85 inches [145-216 cm]) including: Achilles tendon, tibialis posterior and anterior, fibularis longus and brevis, flexor and extensor hallucis longus, plantaris, and flexor digitorum longus. Tendons underwent tensile loading to failure measuring cross-sectional area (CSA), maximum load, strain at failure, ultimate tensile strength, and elastic modulus. Results from 332 tendons were analyzed using mixed-effects linear regression, accounting for donor age, sex, height, and weight. Results: Mechanical properties were significantly different among tendons and were substantially greater than the effects of donor characteristics. Significant effects of donor sex, age, and height were limited to specific tendons: Achilles tendon, tibialis posterior, and tibialis anterior. All other tendons were unaffected. The Achilles tendon was most influenced by donor variables: greater CSA in men (β = 15.45 mm2; Šidák adjusted P < .0001), decreased maximum load with each year of increased age (β = −17.20 N per year; adjusted P = .0253), and increased CSA (β = 1.92 mm2 per inch; adjusted P < .0001) and maximum load (β = 86.40 N per inch; adjusted P < .0001) with each inch of increased height. Conclusion: Mechanical properties vary significantly across different human tendons. The effects of donor age, sex, and height are relatively small, are limited to specific tendons, and affect different tendons uniquely. The findings indicate that age negatively affected only the Achilles tendon (maximum load) and challenge the exclusion of donors aged >65 years across all tendon grafts. Clinical Relevance: The findings support including a broader range of tendons for use as allografts for anterior cruciate ligament reconstruction and reviewing the current exclusion criterion of donors aged >65 years.

A New Approach for Increasing Speed, Loading Capacity, Resolution, and Scalability of Preparative Size-Exclusion Chromatography of Proteins

Low speed, low capacity, and poor scalability make size-exclusion chromatography (SEC) unattractive for use in the preparative separation of proteins. We discuss a novel z2 cuboid SEC device that addresses these challenges. A z2 cuboid SEC device (~24 mL volume) was systematically compared with a conventional SEC column having the same volume and packed with the same resin. The primary objective of this study was to use the same volume of SEC medium in a much more efficient way by using the novel device. At any given flow rate, the pressure drop across the z2 cuboid SEC device was lower by a factor of 6 to 8 due to its shorter bed height and greater cross-sectional area. Under overloaded conditions, the peaks obtained during protein separation with the conventional column were poorly resolved and showed significant fronting, while those obtained with the z2 cuboid SEC device were much better resolved and showed no fronting. At any given flow rate, better resolution was obtained with the z2 cuboid SEC device, while for obtaining a comparable resolution, the flow rate that could be used with the z2 cuboid SEC device was higher by a factor of 2 to 3. Hence, productivity in SEC could easily be increased by 200 to 300% using the z2 cuboid SEC device. The scalability of the z2 cuboid SEC device was also demonstrated based on a device with a 200 mL bed volume.

Age- and sex-dependent differences in the morphology and composition of paraspinal muscles between subjects with and without lumbar degenerative diseases

BackgroundThe quality of the paraspinal muscles has been recommended as a surrogate marker for the evaluation of the severity of the lumbar degenerative diseases (LDD). The purpose of this study is to determine the age- and sex-dependent differences in the morphology and composition of the paraspinal muscles between LDD and asymptomatic subjects.MethodsWe analyzed data from 370 patients and 327 asymptomatic volunteers aged between 18–85 years. The measurement of the cross-sectional area (CSA) of the erector spinae, multifidus, and psoas at the L4/5-disc level was performed by the magnetic resonance imaging (MRI). The fatty infiltration ratio (FI %) of the multifidus and erector spinae was calculated.ResultsFI % of the lumbar paraspinal muscles were significantly and positively correlated with the severity of LDD instead of the CSA. Males had greater CSA than females, and females showed higher FI % than males in the paraspinal muscles. With the increase of age, the CSA of the lumbar paraspinal muscles gradually decreased, and the psoas showed the most significant decreasing trend. However, the FI % gradually increased in both LDD and asymptomatic groups with aging.ConclusionAge- and sex-dependent differences were found in the morphology and composition of the paraspinal muscles between subjects with and without LDD. Further long-term follow up investigations and basic studies will continue to confirm the natural history of the paraspinal muscles with aging and their association with LDD.

Relationships Between Muscle Parameters and History of Falls and Fractures in the Hertfordshire Cohort Study: Do All Muscle Components Relate Equally to Clinical Outcomes?

In previous work, relationships between muscle and bone size and strength have been demonstrated and were stronger in females, suggesting possible sexual dimorphism. Here we examine sex-specific associations between individual muscle sarcopenia components with clinical outcomes (falls and fractures). 641 participants were recruited. Muscle mass was assessed as cross-sectional area (CSA) by peripheral quantitative computed tomography of the calf, grip strength (GpS) by Jamar dynamometry and function by gait speed (GtS). Falls and fractures were self-reported. Ordinal and logistic regression were used to examine the associations between muscle measurements and outcomes with and without adjustment for confounders. Mean (SD) age was 69.3 (2.6) years. CSA, GpS, and GtS were greater among males (p < 0.002). A higher proportion of females had fallen since age 45 (61.3% vs 40.2%, p < 0.001); in the last year (19.9% vs 14.1%, p = 0.053); and reported a previous fracture since age 45 (21.8% vs 18.5%, p = 0.302), than males. Among females, greater CSA was related to reduced risk of falling and fewer falls in the previous year in fully adjusted analysis only (p < 0.05); higher GpS was related to lower risk of falls since age 45 in unadjusted analysis (p = 0.045) and lower risk of fracture since age 45 in both unadjusted and fully adjusted analysis (p < 0.045). No statistically significant associations were observed for GtS among either sex for any relationships between muscle measurements and clinical outcomes studied. We observed relationships between muscle mass and strength but not function with falls and fractures in females only; further longitudinal studies are required to reproduce these results.

Geranylgeraniol Supplementation Mitigates Soleus Muscle Atrophy via Changes in Mitochondrial Quality in Diabetic Rats.

With diabetes, skeletal muscle mitochondrial quality (fusion, fission & mitophagy) and muscle mass are compromised. Geranylgeraniol (GGOH) can prevent mitochondrial damage, inflammation, and improve muscle health; however, the effect of GGOH on a diabetic model is not known. This study aimed to determine the effect of GGOH on mitochondrial quality and muscle mass in diabetic rats. Sprague-Dawley rats were divided into three groups: regular diet (CON; n=7), high-fat-diet with 35 mg/kg body weight of streptozotocin (STZ) (HFD; n=7), and HFD/STZ with 800 mg/kg of GGOH (GG; n=7) for a total of 8 weeks. At the end of the study, soleus and gastrocnemius muscles were collected and analyzed for gene and protein expression of OPA1, MFN2, DRP1, p-DRP, LC3AB, PINK1, Parkin, SOD2, NF-[Formula: see text]B, IL-6, TNF-α, and IL-1β. Additionally, the cross-sectional area (CSA) of soleus muscles was analyzed. In soleus, HFD group had significantly higher IL-1β and lower LC3A, MFN2, DRP1, and SOD2 mRNA expression compared to CON group. The GG group had higher PINK1 mRNA expression than the HFD group. Additionally, the GG group had lower LC3B and DRP1 protein than the HFD group and lower LC3A and MFN2 protein than the HFD and CON groups. Lastly, HFD and GG groups had a smaller CSA than CON group, whereas GG had a greater CSA than HFD. GGOH supplementation could prevent mitochondrial fragmentation and potentially decrease the demand for mitochondrial fusion. Additionally, autophagosome degradation occurred at a greater rate than formation, indicating increased clearance of damaged organelles. Improved mitochondrial quality could potentially rescue muscle CSA in diabetic rats with GGOH supplementation.

Effects of extended postmortem aging and intramuscular location on protein degradation, muscle fiber morphometrics, and tenderness of beef longissimus lumborum and semitendinosus steaks.

The objective of this study was to determine effects of extended aging and intramuscular location on Warner-Bratzler shear force (WBSF), muscle fiber cross-sectional area (CSA), and protein degradation of semitendinosus (ST) and longissimus lumborum (LL) steaks. Left ST and LL were removed from 40 carcasses at 6 d postmortem. The ST was fabricated into five locations (LOC), with LOC 1 being most proximal and LOC 5 being most distal. The posterior LL was fabricated into 3 LOC, with LOC 1 being most anterior. Vacuum sealed ST steaks were aged 7, 14, 28, 56, or 112 d postmortem, while LL steaks were aged 7, 28, or 112 d postmortem at 2 ± 1 °C. A steak from each LOC was assigned to WBSF or laboratory analyses. There were no Day of Aging (DOA) × LOC interactions for all dependent variables (P > 0.06). There were DOA effects for ST and LL WBSF values and degraded 38-kDa desmin (DES; P < 0.01). Day-7 ST-steak WBSF value was greater than all other days (P < 0.01) and day-14 steaks had greater WBSF value than remaining days (P < 0.05). Day-28 ST-steak WBSF values were greater than day 56 and 112 (P < 0.01), which did not differ (P = 0.53). In the LL, day-7 steaks had greater WBSF values than the other two timepoints (P < 0.01) and day-28 steaks had greater (P < 0.01) WBSF values than day-112 steaks. Degraded ST 38-kDa DES content was less on day 7 and 14 compared to all other days (P < 0.03), but did not differ (P = 0.79) from each other. Days 28 and 56 38-kDa DES content was less than day 112 (P < 0.01), but did not differ (P = 0.34) from each other. Degraded LL 38-kDa DES content was less on day 7 than day 28 and 112 (P < 0.02), which did not differ (P = 0.67). There were LOC effects for only ST WBSF and muscle fiber CSA (P < 0.05). Semitendinosus steak LOC 1 and 2 had greater WBSF values than all other locations (P < 0.01), but did not differ (P = 0.32) from each other. Semitendinosus steak LOC 3 and 5 had greater WBSF values than LOC 4 (P < 0.01), but did not differ (P = 0.85) from each other. The CSA of all ST fiber types were largest in LOC 1 compared to all other fiber types (P < 0.01). The CSA of all LOC 2 and 3 fiber types was greater than LOC 4 and 5 (P < 0.01), but were not different from each other (P > 0.81), and LOC 4 had greater CSA than LOC 5 (P < 0.01). Steak aging WBSF value improvements seemed proteolysis catalyzed, while the ST intramuscular tenderness gradient was more likely due to muscle fiber CSA.

Habitual side-specific loading leads to structural, mechanical, and compositional changes in the patellar tendon of young and senior lifelong male athletes.

Effects of lifelong physical activity on tendon function have been investigated in cross-sectional studies, but these are at risk of "survivorship" bias. Here, we investigate whether lifelong side-specific loading is associated with greater cross-sectional area (CSA), mechanical properties, cell density (DNA content), and collagen cross-link composition of the male human patellar tendon (PT), in vivo. Nine seniors and six young male lifelong elite badminton players and fencers were included. CSA of the PT obtained by 3-tesla MRI and ultrasonography-based bilateral PT mechanics were assessed. Collagen fibril characteristics, enzymatic cross links, nonenzymatic glycation (autofluorescence), collagen, and DNA content were measured biochemically in PT biopsies. The elite athletes had a ≥15% side-to-side difference in maximal knee extensor strength, reflecting chronic unilateral sport-specific loading patterns. The PT CSA was greater on the lead extremity compared with the nonlead extremity (17%, P = 0.0001). Furthermore, greater tendon stiffness (18%, P = 0.0404) together with lower tendon stress (22%, P = 0.0005) and tendon strain (18%, P = 0.0433) were observed on the lead extremity. No effects were demonstrated from side-to-side for glycation, enzymatic cross link, collagen, and DNA content (50%, P = 0.1160). Moreover, tendon fibril density was 87 ± 28 fibrils/μm2 on the lead extremity and 68 ± 26 fibrils/μm2 on the nonlead extremity (28%, P = 0.0544). Tendon fibril diameter was 86 ± 14 nm on the lead extremity and 94 ± 14 nm on the nonlead extremity (-9%, P = 0.1076). These novel data suggest that lifelong side-specific loading in males yields greater patellar tendon size and stiffness possibly with concomitant greater fibril density but without changes of collagen cross-link composition.NEW & NOTEWORTHY The present data demonstrate that lifelong side-specific loading yields greater patellar tendon structure on the lead extremity without affecting glycation that is associated with aging. These novel data suggest that lifelong side-specific habitual loading induce structural alterations that may serve to improve the mechanical properties of the tendon.

Gender Difference in Architectural and Mechanical Properties of Medial Gastrocnemius-Achilles Tendon Unit In Vivo.

This study aims to explore whether gender differences exist in the architectural and mechanical properties of the medial gastrocnemius–Achilles tendon unit (gMTU) in vivo. Thirty-six healthy male and female adults without training experience and regular exercise habits were recruited. The architectural and mechanical properties of the gMTU were measured via an ultrasonography system and MyotonPRO, respectively. Independent t-tests were utilized to quantify the gender difference in the architectural and mechanical properties of the gMTU. In terms of architectural properties, the medial gastrocnemius (MG)’s pennation angle and thickness were greater in males than in females, whereas no substantial gender difference was observed in the MG’s fascicle length; the males possessed Achilles tendons (ATs) with a longer length and a greater cross-sectional area than females. In terms of mechanical properties, the MG’s vertical stiffness was lower and the MG’s logarithmic decrement was greater in females than in males. Both genders had no remarkable difference in the AT’s vertical stiffness and logarithmic decrement. Gender differences of individuals without training experience and regular exercise habits exist in the architectural and mechanical properties of the gMTU in vivo. The MG’s force-producing capacities, ankle torque, mechanical efficiency and peak power were higher in males than in females. The load-resisting capacities of AT were greater and the MG strain was lesser in males than in females. These findings suggest that males have better physical fitness, speed and performance in power-based sports events than females from the perspective of morphology and biomechanics.

Comparisons of muscle strength, size, and voluntary activation in pre- and post-pubescent males and females.

The purpose of this study was to compare measurements of muscle strength, size, and activation of the forearm flexors in pre- and post-pubescent males and females. Forty pre-pubescent (mean ± 95% confidence interval, age = 9.79 ± 0.35years, n = 10 males, n = 10 females) and post-pubescent (age = 17.23 ± 0.58years, n = 10 males, n = 10 females) youth participated. Subjects completed maximal voluntary isometric contractions (MVICs) of the forearm flexors, and submaximal isometric step muscle actions at 30, 50, and 70% of the peak MVIC. Percent voluntary activation (VA) was quantified during all isometric muscle actions. Forearm flexor (biceps brachii and brachialis) muscle cross-sectional area (CSA) was quantified from ultrasound images. MVIC strength was expressed in absolute terms and normalized to CSA. Post-pubertal males were 130% stronger, had 101% greater CSA, and 17% greater maximal VA than pre-pubertal males, while post-pubertal females were 72% stronger, had 54% greater CSA, and 23% greater maximal VA than pre-pubertal females. When MVIC strength was normalized to CSA, the post-pubertal males were still 15% stronger than the pre-pubertal males, while the post-pubertal females were only 12% stronger than the pre-pubertal females. The responses for VA across intensity reflected differences in muscle activation strategies between pre- and post-pubertal males and females. These results suggest that muscle size may account for a greater proportion of the growth and development-related differences in strength among males, while females may be more affected by changes in muscle activation. Regardless of sex, changes in muscle size and neuromuscular function influence strength increases during growth and development.

Bone mineral density and hip structure changes over one-year in collegiate distance runners and non-athlete controls

Modification of bone is continuous throughout life and influenced by many factors, including physical activity. This study investigated changes in areal bone mineral density (aBMD) and hip structure among male and female collegiate distance runners and non-athlete controls over 12 months. Using dual-energy x-ray absorptiometry (DXA) and hip structure analysis (HSA) software, aBMD at the posterior-anterior (PA) and lateral spine, femoral neck, total hip (TH), whole body (WB), and bone geometry at the narrow neck (NN) of the femur was measured three times over 12 months. HSA included cross-sectional area (CSA), cross-sectional moment of inertia (CSMI), and Z-section modulus (Z). Male runners had significantly higher aBMD at TH and WB and greater CSA, CSMI, and Z than male controls at the end of 12 months. Female controls had higher aBMD at the PA spine than female runners at the end of 12 months. Male runners had significant increases in aBMD at the PA (p = 0.003) and lateral spine (p = 0.002), and TH (p = 0.002), female runners had significant decreases in aBMD at TH (p = 0.015) and WB (p = 0.002), male controls had significant increases in aBMD at the PA spine (p < 0.001) and WB (p < 0.001), and female controls had significant decreases in aBMD at lateral spine and TH (p = 0.008) over the year. When applying covariates of bone-free lean mass and vitamin D, male distance runners demonstrated significant improvement in CSA (3.602 ± 0.139 vs. 3.675 ± 0.122 cm2, p = 0.05), CSMI (3.324 ± 0.200 to 3.467 ± 0.212 cm4, p < 0.05), and Z (1.81 ± 0.08 to 1.87 ± 0.08 cm3, p = 0.05) during the study. No other changes in hip structure occurred over the year. Distance running may be beneficial to aBMD and hip structure in college-age males but not females. Further research is needed on potential influences of weight-bearing activity, energy availability, and hormonal status on aBMD and hip structure in males and females.

The association between muscle mass and the degree of myosteatosis of the psoas muscle and mortality in older patients with cancer

ObjectiveComprehensive geriatric assessment (CGA) is used for oncological management in older patients. The evaluation of muscle characteristics is currently not included in the CGA. This study investigates whether muscle mass and the degree of myosteatosis is associated with mortality in older patients with cancer. MethodsCGA was performed in a cohort of older patients with cancer. Cross sectional area (CSA) and mean pixel density (Hounsfield units, HU), as measure for respectively muscle mass and myosteatosis, were obtained from CT images of the psoas muscle at the level of mid L3. Mortality was recorded. Correlation was determined between CSA and HU. Paired sample t-test was used to follow changes in muscle mass and density. Logistic regression was performed to define relevant prognostic factors for mortality. ResultsIn total, 183 patients were included (86 male and 97 female), 120 patients (66%) died. Mean age was 80 years (range 70–94 years). Mean days of survival was 606 (range 1–2023). There was a significant correlation between CSA and HU (PCC = 0.196) at time of diagnosis and at follow-up (PCC = 0.257). There was a significant decrease in CSA (p = .008) and HU (p = .004) in men at follow-up. No significant changes were observed in women. In multivariate analysis, a higher gender-corrected CSA was linked to a lower mortality rate with an odds ratio of 0.657 (CI = 0.457–0.944, p = .023). No association was found between HU and mortality. ConclusionsMuscle mass correlated with the degree of myosteatosis. CSA and HU tended to decrease during follow-up. Having a greater CSA was prognostic for a lower mortality rate.

Association between hip muscle cross-sectional area and hip pain and function in individuals with mild-to-moderate hip osteoarthritis: a cross-sectional study

BackgroundTo examine the associations between hip muscle cross-sectional area and hip pain and function in community-based individuals with mild-to-moderate hip osteoarthritis.MethodsThis study included 27 participants with mild-to-moderate hip osteoarthritis. Cross-sectional area of hip muscles, including psoas major, rectus femoris, gluteus maximus, gluteus medius and minimus, adductor longus and magnus, obturator internus, and obturator externus, were measured from magnetic resonance images. Hip pain and function were evaluated using the Hip Disability and Osteoarthritis Outcome Score (HOOS) categorised into 5 subscales: pain, symptoms, activity of daily living, sport and recreation function, and hip-related quality of life (for each subscale 0 representing extreme problems and 100 representing no problems).ResultsMean age of the 27 participants was 63.2 (SD 7.6) years and 66.7% (n = 18) were female. After adjusting for age and gender, greater cross-sectional area of adductor longus and magnus was associated with a higher HOOS score in quality of life (regression coefficient 1.4, 95% confidence interval (CI) 0.2–2.7, p = 0.02), activity of daily living (regression coefficient 1.3, 95% CI 0.1–2.6, p = 0.04) and sport and recreation function (regression coefficient 1.6, 95% CI 0.1–3.0, p = 0.04). There was a trend towards an association between greater cross-sectional area of psoas major and a higher quality of life score (regression coefficient 3.6, 95% CI − 0.5 to 7.7, p = 0.08). The cross-sectional area of hip muscles was not significantly associated with HOOS pain or symptom score.ConclusionGreater cross-sectional area of hip adductors was associated with better function and quality of life in individuals with mild-to-moderate hip osteoarthritis. Greater cross-sectional area of hip flexors might be associated with better quality of life. These findings, while need to be confirmed in longitudinal studies, suggest that targeting the hip adductor and flexor muscles may improve function and quality of life in those with mild-to-moderate hip osteoarthritis.

Sex-related differences in motor unit firing rates and action potential amplitudes of the first dorsal interosseous during high-, but not low-intensity contractions.

Despite ample evidence that females are weaker and possess smaller muscle cross-sectional areas (CSAs) compared to males, it remains unclear if there are sex-related differences in the properties of motor units (MU). Eleven males (age 22 ± 3years) and 12 females (age 21 ± 1years) performed isometric trapezoid muscle actions at 10% and 70% of maximal voluntary contraction (MVC). Surface electromyography signals were recorded and decomposed into MU action potential (AP) waveforms and firing instances. Average MUAP amplitudes (MUAPAMPS), mean firing rates (MFRs), initial firing rates (IFRs), and recruitment thresholds (RT) were calculated for the 10% MVC, while MUAPAMPS, IFRs, and MFRs were regressed against RT for the 70% MVC. Ultrasonography was used to measure CSA of the first dorsal interosseous (FDI). Males had greater CSAs (p < 0.001; males 2.34 ± 0.28cm2, females 1.82 ± 0.18cm2) and MVC strength (p < 0.001; males 25.9 ± 5.5N, females 16.44 ± 2.5N). No differences existed for MUAPAMPS, IFRs, MFRs, or RTs (p > 0.05) during the 10% MVC. For the 70% MVC, the y-intercepts from the MUAPAMPS vs. RT relationships were greater (p < 0.05) for the males (males - 0.19 ± 0.53mV; females - 0.78 ± 0.75mV), while the inverse was true for the MFR vs. RT relationships (males 31.55 ± 6.92pps, females 38.65 ± 6.71pps) with no differences (p > 0.05) in the slopes. Therefore, smaller CSAs and weaker MVCs are likely the result of smaller higher-threshold MUs for females.

Longitudinal Assessment of Quadriceps Muscle Morphology Before and After Anterior Cruciate Ligament Reconstruction and Its Associations With Patient-Reported Outcomes.

Reductions in muscle size are common after anterior cruciate ligament reconstruction (ACLR) and may contribute to suboptimal patient outcomes. However, few studies have quantified postoperative alterations in muscle quality and evaluated its associations with patient-reported function. Rectus femoris cross-sectional area (CSA) will decrease postoperatively but improve at return to activity (RTA), rectus femoris muscle quality (percentage fat [PF]) will increase postoperatively and be greater at RTA compared with preoperative values, and rectus femoris CSA and PF will be associated with International Knee Documentation Committee (IKDC) scores at both postoperative time points. Case series. Level 4. A total of 26 individuals who sustained an ACL injury and underwent reconstructive surgery were evaluated preoperatively (T0), 9 weeks post-ACLR (T1), and at RTA. Rectus femoris CSA and PF were evaluated bilaterally via ultrasound imaging, and patient-reported function was assessed using the IKDC score. Bilateral reductions in rectus femoris CSA were noted from T0 to T1 (P < 0.01). Only the uninvolved limb returned to preoperative CSA (P = 0.80), as the involved limb failed to return to preoperative levels at RTA (P = 0.04). No significant changes in rectus femoris PF were observed across time points (P > 0.05). Lesser PF (P < 0.01) but not CSA (P = 0.75) was associated with higher IKDC score at T1. Lesser PF (P = 0.04) and greater CSA (P = 0.05) was associated with higher IKDC score at RTA. Substantial atrophy occurs bilaterally after ACLR, and the involved limb does not return to preoperative muscle size despite the patient completing rehabilitation. Quadriceps muscle morphology is associated with patient-reported function and may be an important rehabilitation target after ACLR. Quadriceps atrophy and poor muscle quality may contribute to suboptimal patient functioning and quadriceps dysfunction and may be important in RTA decision making. Assessing muscle morphology using ultrasound may be a feasible and clinically beneficial tool in patients after ACLR.

Effect of Viscoelasticity on Arterial-Like Pulsatile Flow Dynamics and Energy.

Time-dependent arterial wall property is an important but difficult topic in vascular mechanics. Hysteresis, which appears during the measurement of arterial pressure-diameter relationship through a cardiac cycle, has been used to indicate time-dependent mechanics of arteries. However, the cause-effect relationship between viscoelastic (VE) properties of the arterial wall and hemodynamics, particularly the viscous contribution to hemodynamics, remains challenging. Herein, we show direct comparisons between elastic (E) (loss/storage < 0.1) and highly viscoelastic (loss/storage > 0.45) conduit structures with arterial-like compliance, in terms of their capability of altering pulsatile flow, wall shear, and energy level. Conduits were made from varying ratio of vinyl- and methyl-terminated poly(dimethylsiloxane) and were fit in a mimetic circulatory system measuring volumetric flow, pressure, and strain. Results indicated that when compared to elastic conduits, viscoelastic conduits attenuated lumen distension waveforms, producing an average of 11% greater cross-sectional area throughout a mimetic cardiac cycle. In response to such changes in lumen diameter strain, pressure and volumetric flow waves in viscoelastic conduits decreased by 3.9% and 6%, respectively, in the peak-to-peak amplitude. Importantly, the pulsatile waveforms for both diameter strain and volumetric flow demonstrated greater temporal alignment in viscoelastic conduits due to pulsation attenuation, resulting in 25% decrease in the oscillation of wall shear stress (WSS). We hope these findings may be used to further examine time-dependent arterial properties in disease prognosis and progression, as well as their use in vascular graft design.

Experimental study of the effect of length and width of the partial and full collars on reduction of scouring and sedimentation patterns around bridge abutments

ABSTRACT The occurrence of local scour around bridge piers or abutments is one of the major reasons for the destruction of bridges. Therefore, this phenomenon should be prevented or at least minimized using some methods, namely using collars in recent years. In the present paper, by proposing a new approach and developing an experimental model of partial collars (collars not fully encircling the abutment), the effect of length and width of collars on reducing scouring and sedimentation pattern around the bridge abutments with vertical walls were investigated under different conditions. Moreover, the obtained results were compared with the results of models with full collars. The results revealed that collar dimensions could have a great impact on its efficiency. In partial collars, if only the upstream face of the abutment is protected and there is no protrusion toward the downstream, there will be no high and acceptable efficiency. However, increasing length and width, its positive efficiency will be enhanced. Although increasing the length of a collar of this type to more than 0.6 times the length of the abutment diminishes the scouring around the bridge abutment, increasing its width not only does reduce the scour depth but also produces a much greater effect on the location of the scouring hole to be farther away from the downstream of the abutment. Furthermore, the efficiency of full collars is also enhanced as their length and width increase. Comparison of the results shows that the efficiency of full collars is less than that of partial collars, despite their greater cross-sectional area. Therefore, partial collars are more cost-effective than full collars due to their lower cross-sectional areas. The average percentage of scour depth reduction for all four flows for different models in the erodible bed and at the base point ranged from 24 to 68% and 24 to 97%, respectively.