Safety testing of Ovaprene: An investigational nonhormonal monthly vaginal contraceptive.

OBJECTIVES: Evaluate the safety of Ovaprene, an investigational nonhormonal vaginal contraceptive designed for monthly use. STUDY DESIGN: Open-label, multicenter study enrolling heterosexually-active women with previous permanent contraception who underwent assessments during five menstrual cycles: baseline postcoital test cycle, diaphragm postcoital test cycle, Ovaprene safety cycle, and two Ovaprene postcoital test cycles. Safety outcomes included treatment-emergent adverse events, systemic laboratory findings, pelvic examinations, colposcopies, Nugent scores, determination of community state types of vaginal microbiota, and anti-Escherichia coli activity and inflammatory markers in cervicovaginal fluids. RESULTS: We enrolled 38 participants. Of these, 33 used Ovaprene and completed 77 Ovaprene cycles. The most common product-related urogenital treatment-emergent adverse events were bacterial vaginosis and vaginal odor. The frequency of transitioning from Lactobacillus-dominated community state type to community state type IV (not Lactobacillus-dominated) was similar before Ovaprene use and afterwards. Mean Nugent scores were <4 at each visit without a discernible upward trend. Inflammatory markers showed wide variation but no upward trend, and E. coli inhibitory activity of cervical secretions did not change. We found no Staphylococcus aureus, the causative agent in toxic shock syndrome, on used Ovaprenes or in vaginal samples. No clinically important changes in systemic laboratory findings, pelvic examinations, or colposcopies occurred during Ovaprene use. CONCLUSIONS: Ovaprene use did not result in cervicovaginal irritation or adverse effects on resident vaginal microbiota and did not impact transitions from a Lactobacillus-dominated community state type to community state type IV. IMPLICATIONS: The finding that the use of Ovaprene, an investigational monthly user-controlled nonhormonal vaginal contraceptive, does not appear to result in adverse changes in vaginal health during short-term use supports further evaluation of the contraceptive potential of the device.

Successful postcoital testing of Ovaprene: An investigational non-hormonal monthly vaginal contraceptive.

OBJECTIVE: Evaluate reduction in progressively motile sperm per high power field (HPF) in midcycle cervical mucus after intercourse with Ovaprene: an investigational monthly non-hormonal vaginal contraceptive consisting of a vaginal ring and mechanical barrier, releasing spermiostatic ferrous gluconate. STUDY DESIGN: Open-label, multicenter study enrolling heterosexually-active women with previous permanent contraception. Participants underwent a baseline postcoital test cycle with no device to confirm the presence of sperm, followed by one diaphragm postcoital test cycle, one Ovaprene safety cycle, and two Ovaprene postcoital test cycles. In each postcoital test cycle, participants underwent a midcycle cervical mucus evaluation to confirm an Insler score ≥10 and absence of sperm, and then returned two to four hours after vaginal intercourse for repeat cervical mucus evaluation. We considered <5 progressively motile sperm/HPF indicative of preliminary contraceptive effectiveness. RESULTS: We enrolled 38 participants; 23 completed the study. All participants had ≥5 progressively motile sperm/HPF in the baseline cycle and <5 progressively motile sperm/HPF in all 49 Ovaprene cycles and all 35 diaphragm cycles, meeting the definition of a successful postcoital test. This was true regardless of examiner blinding, prior vaginal delivery or vaginal ring use, body mass index, or dislodgements noted by the participant or investigator. The mean of 27.2 (±17.9) progressively motile sperm/HPF in baseline postcoital test cycles was reduced to 0.5 (±1.1) and 0.5 (±1.3) progressively motile sperm/HPF in the first and second Ovaprene cycles, respectively. Ovaprene fit all participants and all could insert, position, and remove it. CONCLUSION: Use of Ovaprene resulted in meeting the prespecified criterion for contraceptive effect by all participants during all postcoital test cycles. IMPLICATIONS: The finding that use of Ovaprene, an investigational monthly non-hormonal vaginal contraceptive, resulted in postcoital testing of cervical mucus that met the pre-specified definition of success (<5 progressively motile sperm/HPF) supports further evaluation of contraceptive efficacy of the device in users at risk for pregnancy.

Authenticity in Objects and Activities: Determinants of Satisfaction with Virtual Reality Experiences of Heritage and Non-Heritage Tourism Sites.

Virtual Reality (VR) is becoming an increasingly important technology in a host of industries, including tourism. VR can provide virtual experiences before, during, or in lieu of real-world visits to tourism sites. Hence, providing authentic experiences is essential to satisfy guests with the site and technology. This study analyzes survey data using PLS to identify the determinants of satisfaction with non-immersive VR experiences of heritage and non-heritage tourism sites. Results from 193 subjects reveal the linkages between system quality, object-related authenticity, activity-related authenticity, and presence, as well their relationship with satisfaction.

17-OHPC to Prevent Recurrent Preterm Birth in Singleton Gestations (PROLONG Study): A Multicenter, International, Randomized Double-Blind Trial.

BACKGROUND: Women with a history of spontaneous preterm birth (SPTB) are at a significantly increased risk for recurrent preterm birth (PTB). To date, only one large U.S. clinical trial comparing 17-OHPC (17-α-hydroxyprogesterone caproate or "17P") to placebo has been published, and this trial was stopped early due to a large treatment benefit. OBJECTIVE: This study aimed to assess whether 17-OHPC decreases recurrent PTB and neonatal morbidity in women with a prior SPTB in a singleton gestation. STUDY DESIGN: This was a double-blind, placebo-controlled international trial involving women with a previous singleton SPTB (clinicaltrials.gov: NCT01004029). Women were enrolled at 93 clinical centers (41 in the United States and 52 outside the United States) between 160/7 to 206/7 weeks in a 2:1 ratio, to receive either weekly intramuscular (IM) injections of 250 mg of 17-OHPC or an inert oil placebo; treatment was continued until delivery or 36 weeks. Co-primary outcomes were PTB < 35 weeks and a neonatal morbidity composite index. The composite included any of the following: neonatal death, grade 3 or 4 intraventricular hemorrhage, respiratory distress syndrome, bronchopulmonary dysplasia, necrotizing enterocolitis, or proven sepsis. A planned sample size of 1,707 patients was estimated to provide 98% power to detect a 30% reduction in PTB < 35 weeks (30% to 21%) and 90% power to detect a 35% reduction in neonatal composite index (17%-11%) using a two-sided type-I error of 5%. Finally, this sample size would also provide 82.8% power to rule out a doubling in the risk of fetal/early infant death assuming a 4% fetal/early infant death rate. Analysis was performed according to the intention-to-treat principle. RESULTS: Baseline characteristics between the 1,130 women who received 17-OHPC and 578 women who received placebo were similar. Overall, 87% of enrolled women were Caucasian, 12% had >1 prior SPTB, 7% smoked cigarettes, and 89% were married/lived with partner. Prior to receiving study drug, 73% women had a transvaginal cervical length measurement performed and <2% had cervical shortening <25 mm. There were no significant differences in the frequency of PTB < 35 weeks (17-OHPC 11.0% vs. placebo 11.5%; relative risk = 0.95 [95% confidence interval (CI): 0.71-1.26]) or neonatal morbidity index (17-OHPC 5.6% vs. placebo 5.0%; relative risk = 1.12 [95% CI: 0.68-1.61]). There were also no differences in frequency of fetal/early infant death (17-OHPC 1.7% vs. placebo 1.9%; relative risk = 0.87 [95% CI: 0.4-1.81]. Maternal outcomes were also similar. In the subgroup of women enrolled in the United States (n = 391; 23% of all patients), although the rate of PTB < 35 weeks was higher than the overall study population, there were no statistically significant differences between groups (15.6% vs. 17.6%; relative risk = 0.88 [95% CI: 0.55, 1.40]. CONCLUSION: In this study population, 17-OHPC did not decrease recurrent PTB and was not associated with increased fetal/early infant death.

Consistent expression pattern of myogenic regulatory factors in whole muscle and isolated human muscle satellite cells after eccentric contractions in humans.

Skeletal muscle satellite cells (SC) play an important role in muscle repair following injury. The regulation of SC activity is governed by myogenic regulatory factors (MRF), including MyoD, Myf5, myogenin, and MRF4. The mRNA expression of these MRF in humans following muscle damage has been predominately measured in whole muscle homogenates. Whether the temporal expression of MRF in a whole muscle homogenate reflects SC-specific expression of MRF remains largely unknown. Sixteen young men (23.1 ± 1.0 yr) performed 300 unilateral eccentric contractions (180°/s) of the knee extensors. Percutaneous muscle biopsies from the vastus lateralis were taken before (Pre) and 48 h postexercise. Fluorescence-activated cell sorting analysis was utilized to purify NCAM+ muscle SC from the whole muscle homogenate. Forty-eight hours post-eccentric exercise, MyoD, Myf5, and myogenin mRNA expression were increased in the whole muscle homogenate (~1.4-, ~4.0-, ~1.7-fold, respectively, P < 0.05) and in isolated SC (~19.3-, ~17.5-, ~58.9-fold, respectively, P < 0.05). MRF4 mRNA expression was not increased 48 h postexercise in the whole muscle homogenate (P > 0.05) or in isolated SC (P > 0.05). In conclusion, our results suggest that the directional changes in mRNA expression of the MRF in a whole muscle homogenate in response to acute eccentric exercise reflects that observed in isolated muscle SC.NEW & NOTEWORTHY The myogenic program is controlled via transcription factors referred to as myogenic regulatory factors (MRF). Previous studies have derived MRF expression from whole muscle homogenates, but little work has examined whether the mRNA expression of these transcripts reflects the pattern of expression in the actual population of satellite cells (SC). We report that MRF expression from an enriched SC population reflects the directional pattern of expression from skeletal muscle biopsy samples following eccentric contractions.

Exercise training differentially alters axial and appendicular marrow cellularity in old mice.

Aging gradually renders bone marrow hematopoietically inactive. Endurance exercise reverses this phenotype in young mice. Here, we determine the effects in aged mice. Twenty-two month old mice (n = 6) underwent a progressive exercise training protocol. In appendicular bones, marrow cellularity increased by 51% (p < 0.05) and marrow CFU, CFU-GM, and CAFC increased by 12%, 71%, and 86%, respectively (p < 0.05). Vertebral cellularity remained unchanged. The mechanical forces associated with treadmill exercise training may be responsible for these observations.

Aerobic exercise in humans mobilizes HSCs in an intensity-dependent manner.

Hematopoietic stem and progenitor cells are necessary to maintain, repair, and reconstitute the hematopoietic blood cell system. Mobilization of these cells from bone marrow to blood can be greatly increased under certain conditions, one such being exercise. The purpose of this study was to identify the importance of exercise intensity in hematopoietic mobilization, to better understand the mobilization kinetics postexercise, and to determine if exercise is capable of mobilizing several specific populations of hematopoietic cells that have clinical relevance in a transplant setting. Healthy individuals were exercised on a cycle ergometer at 70% of their peak work rate (WRpeak) until volitional fatigue and at 30% of their WRpeak work matched to the 70% WRpeak bout. Blood was collected before, immediately post, and 10, 30, and 60 min postexercise. Total blood cells, hematocrit, and mononuclear cells isolated by density gradient centrifugation were counted. Specific populations of hematopoietic stem cells were analyzed by flow cytometry. Mononuclear cells, CD34+, CD34+/CD38-, CD34+/CD110+, CD3-/CD16+/CD56+, CD11c+/CD123-, and CD11c-/CD123+ cells per millilter of blood increased postexercise. Overall, the 70% WRpeak exercise group showed greater mobilization immediately postexercise, while there was no observable increase in mobilization in the work matched 30% WRpeak exercise group. Mobilization of specific populations of hematopoietic cells mirrored changes in the general mobilization of mononuclear cells, suggesting that exercise serves as a nonspecific mobilization stimulus. Evidently, higher intensity exercise is capable of mobilizing hematopoietic cells to a large extent and immediately postexercise is an ideal time point for their collection. NEW & NOTEWORTHY: Here we demonstrate for the first time that mobilization of hematopoietic stem cells (HSCs) through exercise is intensity dependent, with the greatest mobilization occurring immediately after high-intensity exercise. As well, we show that exercise is a general stimulus for mobilization: increases in specific HSC populations are reliant on general mononuclear cell mobilization. Finally, we demonstrate no differences in mobilization between groups with different aerobic fitness.

Exercise conditioning in old mice improves skeletal muscle regeneration.

Skeletal muscle possesses the ability to regenerate after injury, but this ability is impaired or delayed with aging. Regardless of age, muscle retains the ability to positively respond to stimuli, such as exercise. We examined whether exercise is able to improve regenerative response in skeletal muscle of aged mice. Twenty-two-month-old male C57Bl/6J mice (n = 20) underwent an 8-wk progressive exercise training protocol [old exercised (O-Ex) group]. An old sedentary (O-Sed) and a sedentary young control (Y-Ctl) group were included. Animals were subjected to injections of cardiotoxin into the tibialis anterior muscle. The tibialis anterior were harvested before [O-Ex/O-Sed/Y-Ctl control (CTL); n = 6], 10 d (O-Ex/O-Sed/Y-Ctl d 10; n = 8), and 28 d (O-Ex/O-Sed/Y-Ctl d 28; n = 6) postinjection. Average fiber cross-sectional area was reduced in all groups at d 10 (CTL: O-Ex: 2499 ± 140; O-Sed: 2320 ± 165; Y-Ctl: 2474 ± 269; d 10: O-Ex: 1191 ± 100; O-Sed: 1125 ± 99; Y-Ctl: 1481 ± 167 µm(2); P < 0.05), but was restored to control values in O-Ex and Y-Ctl groups at d 28 (O-Ex: 2257 ± 181; Y-Ctl: 2398 ± 171 µm(2); P > 0.05). Satellite cell content was greater at CTL in O-Ex (2.6 ± 0.4 satellite cells/100 fibers) compared with O-Sed (1.0 ± 0.1% satellite cells/100 fibers; P < 0.05). Exercise conditioning appears to improve ability of skeletal muscle to regenerate after injury in aged mice.-Joanisse, S., Nederveen, J. P., Baker, J. M., Snijders, T., Iacono, C., Parise, G. Exercise conditioning in old mice improves skeletal muscle regeneration.

Skeletal Muscle Erythropoietin Expression Is Responsive to Hypoxia and Exercise.

PURPOSE: Erythropoietin is responsible for regulating the growth and development of red blood cells. Reports conflict on whether skeletal muscle is able to produce erythropoietin and release it into circulation and if exercise affects this. We set out to determine how erythropoietin is regulated in skeletal muscle and to determine whether skeletal muscle-derived erythropoietin can stimulate erythropoiesis. METHODS: Using an in vitro approach, we exposed proliferating and differentiated skeletal muscle cells to various forms of exercise-induced physiological stimuli and measured erythropoietin gene expression. To understand if skeletal muscle cells were able to stimulate erythropoiesis, independent of other cell types found in skeletal muscle, we used myoblast-conditioned media to treat bone marrow and to measure erythropoiesis through flow cytometry. We also measured erythropoietin expression and hypoxia in mice subjected to an exercise protocol designed to induce skeletal muscle oxygen stress. RESULTS: Hypoxia increased erythropoietin expression in C2C12 myoblasts, myotubes, and primary myoblasts in vitro by 50% to 130%. Bone marrow treated with media conditioned with hypoxic myoblasts for 24 h increased the number of Ter-119-positive cells by 32%. An erythropoietin-neutralizing antibody prevented this increase. Compared with unexercised controls, exhaustive exercise increased skeletal muscle HIF1α levels by 50% and HIF2α levels by 20%. Moreover, exercised skeletal muscle erythropoietin expression was 70% higher. CONCLUSION: These results demonstrate that skeletal muscle produces erythropoietin in a hypoxia and HIF-dependent manner and that hypoxia-treated muscle is capable of stimulating erythropoiesis in vitro.

The effects of resting and exercise serum from children with cystic fibrosis on C2C12 myoblast proliferation in vitro.

Chronic systemic inflammation is a clinical symptom in children with cystic fibrosis (CF), but the effects on skeletal muscle development are unknown. The aims of this study were to determine (1) the effects of systemic factors from children with CF and healthy controls on myoblast proliferation, and (2) whether exercise serum can have an effect on proliferation in vitro. Eleven children with CF and 11 biological age-matched controls completed two 30-min bouts of cycling at an intensity set at 50% peak mechanical power. Serum samples were collected before exercise (REST), immediately following exercise (EX), and after 60 min of recovery (REC). Serum samples prepared in group-specific pools were used for cell culture experiments. C2C12 myoblasts were incubated in 5% serum and media for 1 h and then immediately harvested for protein and mRNA analysis, or incubated in growth media for 2 days to examine proliferation. C2C12 myoblasts treated with CF serum displayed greater proliferation phenotype than myoblasts treated with control serum. Proliferation did not change with EX or REC serum from children with CF compared to CF REST serum, while proliferation was increased with EX and REC serum from control compared to control REST serum. These findings suggest that systemic factors from children with CF at rest and after exercise can alter myoblast proliferation responses when compared to systemic factors from healthy children, which may have implications on skeletal muscle development.

Reduced fat oxidation rates during submaximal exercise in boys with cystic fibrosis.

BACKGROUND: Exercise is a viable form of therapy for children with cystic fibrosis (CF). Understanding the energy sources used during exercise would aid CF patients in obtaining proper nutrition in order to sustain an active lifestyle. METHODS: Six boys with CF (mean age ± SD: 14.8 ± 2.3 yrs, FEV1: 99 ± 18% predicted) and six matched controls (14.0 ± 2.2 yrs) completed a session of two 30 min bouts of cycling at an intensity set at 50% peak mechanical power. Rates of total fat and carbohydrate (CHO) oxidation were calculated from expired gases. Plasma insulin, glucose and free fatty acid (FFA) were determined before, during and at the end of the exercise. RESULTS: Rates of fat oxidation (expressed in mean mg × kg body weight(-1) × min(-1) ± SD) were significantly lower in children with CF (5.7 ± 1.6) compared to controls (8.6 ± 1.8, p < 0.05). Children with CF also had lower values than controls in amount of fat oxidized (CF: 17.3 ± 5.0 g, controls: 26.1 ± 5.9 g, p < 0.05) and percent of total energy expenditure from fat (CF: 32 ± 6%, controls: 43 ± 7%, p < .0.05), but a higher contribution from CHO (CF: 68 ± 6%, controls: 57 ± 7% p < .0.05). Plasma FFA was significantly lower in children with CF compared to controls during (CF: 252.5 ± 117.9 µM, controls: 602.2 ± 295.6) and at the end of exercise (CF: 430.9 ± 180.6, controls: 1147.5 ± 473.5). There were no differences in the rates of CHO oxidation, insulin or glucose between groups. CONCLUSION: Fat metabolism during exercise is impaired in boys with CF and may be attributed to an inability to mobilize FFA.

Reduced fat oxidation rates during submaximal exercise in adolescents with Crohn's disease.

BACKGROUND: Children with Crohn's disease (CD) suffer from malnutrition. Understanding substrate utilization during exercise may help patients with CD sustain a healthy active lifestyle without compromising nutrition. The aim of this study was to determine whether substrate utilization and bioavailability during exercise are altered in children with CD compared with controls. METHODS: Seven children with CD (mean age ± SD: 15.2 ± 2.3 yr) and 7 controls (14.4 ± 2.3 yr) were matched by sex and biological age. Participants completed 60 minutes of cycling at an intensity equivalent to 50% of their peak mechanical power. Rates of total fat and carbohydrate (CHO) oxidation, the amount of fat and CHO oxidized, and the contribution of fat and CHO to total energy expenditure were calculated from expired gases collected during exercise. Blood was collected before, during, and at the end of exercise and analyzed for insulin, free fatty acids, and glucose. RESULTS: Whole-body fat oxidation rate (expressed in mg · kg(-1) of body weight per min) during exercise was lower in children with CD (5.8 ± 1.0) compared with controls (8.0 ± 2.2, P < 0.05). Children with CD relied significantly more on CHO, with approximately 10% greater contribution toward total energy expenditure (P < 0.05) than controls. There were no differences in plasma insulin, free fatty acids, or glucose between the groups. CONCLUSIONS: Fat metabolism during exercise seems to be impaired in children with CD. A greater reliance on CHO is required to meet the energy demands of submaximal exercise.

Elevated SOCS3 and altered IL-6 signaling is associated with age-related human muscle stem cell dysfunction.

Aging is associated with increased circulating interleukin-6 (IL-6) and a reduced myogenic capacity, marked by reduced muscle stem cell [satellite cell (SC)] activity. Although IL-6 is important for normal SC function, it is unclear whether elevated IL-6 associated with aging alters SC function. We hypothesized that mild chronically elevated IL-6 would be associated with a blunted SC response through altered IL-6 signaling and elevated suppressor of cytokine signaling-3 (SOCS3) in the elderly. Nine healthy older adult men (OA; 69.6 ± 3.9 yr) and 9 young male controls (YC; 21. 3 ± 3.1 yr) completed 4 sets of 10 repetitions of unilateral leg press and knee extension (75% of 1-RM). Muscle biopsies and blood were obtained before and 3, 24, and 48 h after exercise. Basal SC number was 33% lower in OA vs. YC, and the response was blunted in OA. IL-6(+)/Pax7(+) cells demonstrated a divergent response in OA, with YC increasing to 69% at 3 h and peaking at 24 h (72%), while IL-6(+)/Pax7(+) cells were not increased until 48 h in OA (61%). Type II fiber-associated phosphorylated signal transducer and activator of transcription (pSTAT3)(+)/Pax7(+) cells demonstrated a similar delay in OA, not increasing until 48 h (vs. 3 h in YC). SOCS3 protein was 86% higher in OA. These data demonstrate an age-related impairment in normal SC function that appears to be influenced by SOCS3 protein and delayed induction of IL-6 and pSTAT3 in the SCs of OA. Collectively, these data suggest dysregulated IL-6 signaling as a consequence of aging contributes to the blunted muscle stem cell response.

Exercise promotes bone marrow cell survival and recipient reconstitution post-bone marrow transplantation, which is associated with increased survival.

Bone marrow transplantation (BMT) is associated with a high risk of mortality, partially because of the harmful effects of the preconditioning myeloablative regimens. We have recently demonstrated increased bone marrow cell survival and proliferation in response to exercise training, which may be attributable to increased quality of the niche. The purpose of the present study was to determine the extent to which exercise preconditioning of recipients could increase the success of BMT. Recipient mice remained sedentary (SED) or were exercise-trained (EX) on a treadmill (3 d/wk for 8 weeks) before reconstitution with green fluorescent protein (GFP)-labeled donor marrow. Recipient survival, both donor-derived and total (donor- and recipient-derived) blood reconstitution were measured by flow cytometry. The first and fourth day after BMT apoptosis, cellularity and donor cell homing were determined in the recipients' bone marrow cavity by flow cytometry. Whereas only 25% of SED mice survived, 82% of EX recipients survived the BMT. Homing of donor-derived marrow cells to the recipients' marrow cavity acutely after BMT was not altered in EX, but EX mice displayed decreased levels (10%; p < 0.05) of activated caspase-3/-7 one day after BMT, leading to a maintenance of marrow cellularity in mice preconditioned with exercise. The acute inhibition of marrow cell apoptosis in EX mice resulted in increased total blood cell reconstitution at 1 and 3.5 months after BMT in EX mice (42% and 43%, respectively; both p < 0.05). Short- and long-term donor-derived engraftment was not different between EX and SED recipients. Exercise training increases recipient survival after BMT with increased total blood cell reconstitution.

Perspectives on introduction and implementation of new point-of-care diagnostic tests.

In recent years, there has been significant investment from both the private and public sectors in the development of diagnostic technologies to meet the need for human immunodeficiency virus (HIV) and tuberculosis testing in low-resource settings. Future investments should ensure that the most appropriate technologies are adopted in settings where they will have a sustainable impact. Achieving these aims requires the involvement of many stakeholders, as their needs, operational constraints, and priorities are often distinct. Here, we discuss these considerations from different perspectives representing those of various stakeholders involved in the development, introduction, and implementation of diagnostic tests. We also discuss some opportunities to address these considerations.

Gait variability in Parkinson's disease: influence of walking speed and dopaminergic treatment.

OBJECTIVES: To study the effects of levodopa and walking speed on gait variability in individuals with Parkinson's disease (PD). METHODS: Thirty-three individuals with PD were studied. Their mean age was 70.61±9.23 year. The average time since diagnosis was 9.65±5.80 year. Gait variability was studied while 'OFF' and 'ON' dopaminergic medication when the subjects walked at their usual and fastest speeds. RESULTS: Variability of step time, double support time, stride length and stride velocity decreased significantly (P=0.037; P=0.037; P=0.022; P=0.043, respectively) after dopaminergic treatment. When subjects increased walking speed, the variability of stride length and stride velocity decreased significantly (P=0.038 and P=0.004, respectively) both while 'OFF' and 'ON' levodopa. Increasing walking speed did not change the variability of step time and double support time regardless of medication status. CONCLUSIONS: Levodopa decreased gait variability in persons with PD. Stride length and stride velocity variability appeared to be speed dependent parameters, whereas, the variability of step time and double support time appeared to be speed independent measures. Levodopa had positive effects on gait stability in PD.

Skeletal muscle myoblasts possess a stretch-responsive local angiotensin signalling system.

A paucity of information exists regarding the presence of local renin-angiotensin systems (RASs) in skeletal muscle and associated muscle stem cells. Skeletal muscle and muscle stem cells were isolated from C57BL/6 mice and examined for the presence of a local RAS using quantitative reverse transcriptase polymerase chain reaction (qRT-PCR), immunohistochemistry (IHC), Western blotting and liquid chromatography-mass spectrometry (LC-MS). Furthermore, the effect of mechanical stimulation on RAS member gene expression was analysed. Whole skeletal muscle, primary myoblasts and C2C12 derived myoblasts and myotubes differentially expressed members of the RAS including angiotensinogen, angiotensin-converting enzyme (ACE), angiotensin II (Ang II) type 1 (AT(1)) and type 2 (AT(2)). Renin transcripts were never detected, however, mRNA for the 'renin-like' enzyme cathepsin D was observed and Ang I and Ang II were identified in cell culture supernatants from proliferating myoblasts. AT(1) appeared to co-localise with polymerised actin filaments in proliferating myoblasts and was primarily found in the nucleus of terminally differentiated myotubes. Furthermore, mechanical stretch of proliferating and differentiating C2C12 cells differentially induced mRNA expression of angiotensinogen, AT(1) and AT(2). Proliferating and differentiated muscle stem cells possess a local stress-responsive RAS in vitro. The precise function of a local RAS in myoblasts remains unknown. However, evidence presented here suggests that Ang II may be a regulator of skeletal muscle myoblasts.

Low-load high volume resistance exercise stimulates muscle protein synthesis more than high-load low volume resistance exercise in young men.

BACKGROUND: We aimed to determine the effect of resistance exercise intensity (%1 repetition maximum-1RM) and volume on muscle protein synthesis, anabolic signaling, and myogenic gene expression. METHODOLOGY/PRINCIPAL FINDINGS: Fifteen men (21+/-1 years; BMI=24.1+/-0.8 kg/m2) performed 4 sets of unilateral leg extension exercise at different exercise loads and/or volumes: 90% of repetition maximum (1RM) until volitional failure (90FAIL), 30% 1RM work-matched to 90%FAIL (30WM), or 30% 1RM performed until volitional failure (30FAIL). Infusion of [ring-13C6] phenylalanine with biopsies was used to measure rates of mixed (MIX), myofibrillar (MYO), and sarcoplasmic (SARC) protein synthesis at rest, and 4 h and 24 h after exercise. Exercise at 30WM induced a significant increase above rest in MIX (121%) and MYO (87%) protein synthesis at 4 h post-exercise and but at 24 h in the MIX only. The increase in the rate of protein synthesis in MIX and MYO at 4 h post-exercise with 90FAIL and 30FAIL was greater than 30WM, with no difference between these conditions; however, MYO remained elevated (199%) above rest at 24 h only in 30FAIL. There was a significant increase in AktSer473 at 24h in all conditions (P=0.023) and mTORSer2448 phosphorylation at 4 h post-exercise (P=0.025). Phosporylation of Erk1/2Tyr202/204, p70S6KThr389, and 4E-BP1Thr37/46 increased significantly (P<0.05) only in the 30FAIL condition at 4 h post-exercise, whereas, 4E-BP1Thr37/46 phosphorylation was greater 24 h after exercise than at rest in both 90FAIL (237%) and 30FAIL (312%) conditions. Pax7 mRNA expression increased at 24 h post-exercise (P=0.02) regardless of condition. The mRNA expression of MyoD and myogenin were consistently elevated in the 30FAIL condition. CONCLUSIONS/SIGNIFICANCE: These results suggest that low-load high volume resistance exercise is more effective in inducing acute muscle anabolism than high-load low volume or work matched resistance exercise modes.

Regulation of muscle satellite cell activation and chemotaxis by angiotensin II.

The role of angiotensin II (Ang II) in skeletal muscle is poorly understood. We report that pharmacological inhibition of Ang II signaling or ablation of the AT1a receptor significantly impaired skeletal muscle growth following myotrauma, in vivo, likely due to impaired satellite cell activation and chemotaxis. In vitro experiments demonstrated that Ang II treatment activated quiescent myoblasts as evidenced by the upregulation of myogenic regulatory factors, increased number of ß-gal+, Myf5-LacZ myoblasts and the acquisition of cellular motility. Furthermore, exogenous treatment with Ang II significantly increased the chemotactic capacity of C2C12 and primary cells while AT1a(-/-) myoblasts demonstrated a severe impairment in basal migration and were not responsive to Ang II treatment. Additionally, Ang II interacted with myoblasts in a paracrine-mediated fashion as 4 h of cyclic mechanical stimulation resulted in Ang II-induced migration of cocultured myoblasts. Ang II-induced chemotaxis appeared to be regulated by multiple mechanisms including reorganization of the actin cytoskeleton and augmentation of MMP2 activity. Collectively, these results highlight a novel role for Ang II and ACE inhibitors in the regulation of skeletal muscle growth and satellite cell function.