Fertilization with follicular fluid reduces HSP70 and BAX expression on bovine in vitro embryos.

The in vivo fertilization process occurs in the presence of follicular fluid (FF). The aim of this study was to evaluate the effect of in vitro fertilization medium supplementation with 5% or 10% bovine follicular fluid (BFF) on the production of in vitro bovine embryos. FF was collected from ovarian follicles with a diameter of 8-10 mm, and cumulus-oocyte complexes (COCs) were co-incubated with sperm for 24 h in the commercial medium BotuFIV® (BotuPharma©), being distributed among the experimental groups: oocytes fertilized in a control medium; oocytes fertilized in a medium supplemented with 5% BFF; and oocytes fertilized in a medium supplemented with 10% BFF. After fertilization, the zygotes were cultured in vitro for 8 days. Embryo development was assessed through cleavage rates (day 2) and blastocyst formation rates (day 8). The relative expression of the genes OCT4, IFNT2, BAX, HSP70 and SOD2 was measured using the real-time polymerase chain reaction method. There was no difference (p > .05) among the different experimental groups in terms of cleavage rates and blastocyst formation rates. Regarding the gene expression results, only the blastocysts from oocytes fertilized with 10% BFF showed significantly lower expression of IFNT2 (p = .003) and SOD2 (p = .01) genes compared to blastocysts from oocytes fertilized in control medium alone, while there was no difference between blastocyst from oocytes fertilized in control medium and the ones from oocytes fertilized with 5% BFF. In addition to this, the blastocysts from oocytes fertilized with 5% BFF showed significantly reduced levels of expression of the heat shock protein HSP70 (p < .001) and the pro-apoptotic protein BAX (p = .015) compared to blastocysts from oocytes fertilized with control medium. This may indicate that lower supplementation of BFF to the IVF medium creates a more suitable environment for fertilization and is less stressful for the zygote.

Vaccine adherence and adverse events of the SARS-COV vaccine in patients with inflammatory bowel disease.

OBJECTIVE: To assess adherence to and the adverse effects of the SARS-COV vaccine in patients with inflammatory bowel disease (IBD). PATIENTS AND METHODS: This is an observational, analytical, cross-sectional study. Sociodemographic and clinical data, SARS-COV vaccine data, medications for IBD with use during the vaccination period, and adverse events during the vaccination period were collected. Carried out logistic regressions with robust variance estimation to estimate the odds ratio with the respective 95% confidence intervals (95%CI) to assess the factors associated with non-serious adverse effects following vaccine doses as outcome variables. RESULTS: 194 patients participated, with vaccine compliance of 78.3% for three doses of any vaccine (n=152). Local symptoms and mild systemic symptoms predominated, regardless of the type of vaccine. The first dose of the SARS-COV vaccine with AstraZeneca had a higher percentage of patients with vaccine symptoms. AstraZeneca vaccine increased the chance of non-serious adverse effects in IBD patients by 2.65 times (95% CI: 1.38-5.08; p=0.003), regardless of age, gender, physical activity, excess weight, use of disease-modifying drugs, immunobiological and corticosteroids. CoronaVac vaccine was associated with asymptomatic patients at the first dose and reduced the chance of adverse effects by 0.28 times (OR: 0.284; 95%CI: 0.13-0.62; p=0.002). CONCLUSION: Local symptoms and mild systemic symptoms predominated, regardless of the type of vaccine. Using CoronaVac in the first dose reduced the chances of adverse effects, while AstraZeneca increased the risk of adverse effects.

E-cigarette aerosol impairs male mouse skeletal muscle force development and prevents recovery from injury.

To date, there has been a lag between the rise in E-cigarette use and an understanding of the long-term health effects. Inhalation of E-cigarette aerosol delivers high doses of nicotine, raises systemic cytokine levels, and compromises cardiopulmonary function. The consequences for muscle function have not been thoroughly investigated. The present study tests the hypothesis that exposure to nicotine-containing aerosol impairs locomotor muscle function, limits exercise tolerance, and interferes with muscle repair in male mice. Nicotine-containing aerosol reduced the maximal force produced by the extensor digitorum longus (EDL) by 30%-40% and, the speed achieved in treadmill running by 8%. Nicotine aerosol exposure also decreased adrenal and increased plasma epinephrine and norepinephrine levels, and these changes in catecholamines manifested as increased muscle and liver glycogen stores. In nicotine aerosol exposed mice, muscle regenerating from overuse injury only recovered force to 80% of noninjured levels. However, the structure of neuromuscular junctions (NMJs) was not affected by e-cigarette aerosols. Interestingly, the vehicle used to dissolve nicotine in these vaping devices, polyethylene glycol (PG) and vegetable glycerin (VG), decreased running speed by 11% and prevented full recovery from a lengthening contraction protocol (LCP) injury. In both types of aerosol exposures, cardiac left ventricular systolic function was preserved, but left ventricular myocardial relaxation was altered. These data suggest that E-cigarette use may have a negative impact on muscle force and regeneration due to compromised glucose metabolism and contractile function in male mice.NEW & NOTEWORTHY In male mice, nicotine-containing E-cigarette aerosol compromises muscle contractile function, regeneration from injury, and whole body running speeds. The vehicle used to deliver nicotine, propylene glycol, and vegetable glycerin, also reduces running speed and impairs the restoration of muscle function in injured muscle. However, the predominant effects of nicotine in this inhaled aerosol are evident in altered catecholamine levels, increased glycogen content, decreased running capacity, and impaired recovery of force following an overuse injury.

Metabolomic and elemental profiling of human tissue in kidney cancer.

INTRODUCTION: Kidney cancer is one of the most frequently diagnosed and the most lethal urinary cancer. Despite advances in treatment, no specific biomarker is currently in use to guide therapeutic interventions. OBJECTIVES: Major aim of this work was to perform metabolomic and elemental profiling of human kidney cancer and normal tissue and to evaluate cancer biomarkers. METHODS: Metabolic and elemental profiling of tumor and adjacent normal human kidney tissue from 50 patients with kidney cancer was undertaken using three different analytical methods. RESULTS: Five potential tissue biomarkers of kidney cancer were identified and quantified using with high-resolution nuclear magnetic resonance spectroscopy. The contents of selected chemical elements in tissues was analyzed using inductively coupled plasma optical emission spectrometry. Eleven mass spectral features differentiating between kidney cancer and normal tissues were detected using silver-109 nanoparticle enhanced steel target laser desorption/ionization mass spectrometry. CONCLUSIONS: Our results, derived from the combination of ICP-OES, LDI MS and 1H NMR methods, suggest that tissue biomarkers identified herein appeared to have great potential for use in clinical prognosis and/or diagnosis of kidney cancer.

Influence of muscle oxygenation and nitrate-rich beetroot juice supplementation on O2 uptake kinetics and exercise tolerance.

We tested the hypothesis that acute supplementation with nitrate (NO3-)-rich beetroot juice (BR) would improve quadriceps muscle oxygenation, pulmonary oxygen uptake (V˙O2) kinetics and exercise tolerance (Tlim) in normoxia and that these improvements would be augmented in hypoxia and attenuated in hyperoxia. In a randomised, double-blind, cross-over study, ten healthy males completed two-step cycle tests to Tlim following acute consumption of 210 mL BR (18.6 mmol NO3-) or NO3--depleted beetroot juice placebo (PL; 0.12 mmol NO3-). These tests were completed in normobaric normoxia [fraction of inspired oxygen (FIO2): 21%], hypoxia (FIO2: 15%) and hyperoxia (FIO2: 40%). Pulmonary V˙O2 and quadriceps tissue oxygenation index (TOI), derived from multi-channel near-infrared spectroscopy, were measured during all trials. Plasma [nitrite] was higher in all BR compared to all PL trials (P < 0.05). Quadriceps TOI was higher in normoxia compared to hypoxia (P < 0.05) and higher in hyperoxia compared to hypoxia and normoxia (P < 0.05). Tlim was improved after BR compared to PL ingestion in the hypoxic trials (250 ± 44 vs. 231 ± 41 s; P = 0.006; d = 1.13), with the magnitude of improvement being negatively correlated with quadriceps TOI at Tlim (r = -0.78; P < 0.05). Tlim was not improved following BR ingestion in normoxia (BR: 364 ± 98 vs. PL: 344 ± 78 s; P = 0.087, d = 0.61) or hyperoxia (BR: 492 ± 212 vs. PL: 472 ± 196 s; P = 0.273, d = 0.37). BR ingestion increased peak V˙O2 in hypoxia (P < 0.05), but not normoxia or hyperoxia (P > 0.05). These findings indicate that BR supplementation is more likely to improve Tlim and peak V˙O2 in situations when skeletal muscle is more hypoxic.

Incubation with sodium nitrite attenuates fatigue development in intact single mouse fibres at physiological PO2.

KEY POINTS: Dietary nitrate supplementation increases plasma nitrite concentration, which provides an oxygen-independent source of nitric oxide and can delay skeletal muscle fatigue. Nitrate supplementation has been shown to increase myofibre calcium release and force production in mouse skeletal muscle during contractions at a supra-physiological oxygen tension, but it is unclear whether nitrite exposure can delay fatigue development and improve myofibre calcium handling at a near-physiological oxygen tension. Single mouse muscle fibres acutely treated with nitrite had a lower force and cytosolic calcium concentration during single non-fatiguing contractions at a near-physiological oxygen tension. Nitrite treatment delayed fatigue development during repeated fatiguing isometric contractions at near-physiological, but not at supra-physiological, oxygen tension in combination with better maintenance of myofilament calcium sensitivity and sarcoplasmic reticulum calcium pumping. These findings improve understanding of the mechanisms by which increased skeletal muscle nitrite exposure might be ergogenic and imply that this is related to improved calcium handling. ABSTRACT: Dietary nitrate (NO3- ) supplementation, which increases plasma nitrite (NO2- ) concentration, has been reported to attenuate skeletal muscle fatigue development. Sarcoplasmic reticulum (SR) calcium (Ca2+ ) release is enhanced in isolated single skeletal muscle fibres following NO3- supplementation or NO2- incubation at a supra-physiological PO2 but it is unclear whether NO2- incubation can alter Ca2+ handling and fatigue development at a near-physiological PO2 . We hypothesised that NO2- treatment would improve Ca2+ handling and delay fatigue at a physiological PO2 in intact single mouse skeletal muscle fibres. Each muscle fibre was perfused with Tyrode solution pre-equilibrated with either 20% ( PO2 ∼150 Torr) or 2% O2 ( PO2  = 15.6 Torr) in the absence and presence of 100 µM NaNO2 . At supra-physiological PO2 (i.e. 20% O2 ), time to fatigue was lowered by 34% with NaNO2 (control: 257 ± 94 vs. NaNO2 : 159 ± 46 s, Cohen's d = 1.63, P < 0.05), but extended by 21% with NaNO2 at 2% O2 (control: 308 ± 217 vs. NaNO2 : 368 ± 242 s, d = 1.14, P < 0.01). During the fatiguing contraction protocol completed with NaNO2 at 2% O2 , peak cytosolic Ca2+ concentration ([Ca2+ ]c ) was not different (P > 0.05) but [Ca2+ ]c accumulation between contractions was lower, concomitant with a greater SR Ca2+ pumping rate (P < 0.05) compared to the control condition. These results demonstrate that increased exposure to NO2- blunts fatigue development at near-physiological, but not at supra-physiological, PO2 through enhancing SR Ca2+ pumping rate in single skeletal muscle fibres. These findings extend our understanding of the mechanisms by which increased NO2- exposure can mitigate skeletal muscle fatigue development.

A mitochondrial-targeted antioxidant improves myofilament Ca2+ sensitivity during prolonged low frequency force depression at low PO2.

KEY POINTS: Skeletal muscle contractile activity is associated with an enhanced reactive oxygen species (ROS) generation. At very low PO2, ROS generation by mitochondria can be elevated in intact cells. An elevated intracellular oxidant activity may affect muscle force development and recovery from fatigue. We treated intact single muscle fibres with a mitochondrial antioxidant and stimulated the fibres to contract at a low extracellular PO2 that is similar to the intracellular PO2 that is observed during moderate to intense exercise in vivo. The mitochondrial antioxidant prevented a sustained decrease in the myofibrillar Ca2+ sensitivity and improved muscle submaximal force development after fatigue at low extracellular PO2. ABSTRACT: Skeletal muscle can develop a prolonged low frequency-stimulation force depression (PLFFD) following fatigue-inducing contractions. Increased levels of reactive oxygen species (ROS) have been implicated in the development of PLFFD. During exercise the skeletal muscle intracellular PO2 decreases to relatively low levels, and can be further decreased when there is an impairment in O2 diffusion or availability, such as in certain chronic diseases and during exercise at high altitude. Since ROS generation by mitochondria is elevated at very low PO2 in cells, we tested the hypothesis that treatment of muscle fibres with a mitochondrial-targeted antioxidant at a very low, near hypoxic, PO2 can attenuate PLFFD. We treated intact single fibres from mice with the mitochondrial-specific antioxidant SS31, and measured force development and intracellular [Ca2+ ] 30 min after fatigue at an extracellular PO2 of ∼5 Torr. After 30 min following the end of the fatiguing contractions, fibres treated with SS31 showed significantly less impairment in force development compared to untreated fibres at submaximal frequencies of stimulation. The cytosolic peak [Ca2+ ] transients (peak [Ca2+ ]c ) were equally decreased in both groups compared to pre-fatigue values. The combined force and peak [Ca2+ ]c data demonstrated that myofibrillar Ca2+ sensitivity was diminished in the untreated fibres 30 min after fatigue compared to pre-fatigue values, but Ca2+ sensitivity was unaltered in the SS31 treated fibres. These results demonstrate that at a very low PO2, treatment of skeletal muscle fibres with a mitochondrial antioxidant prevents a decrease in the myofibrillar Ca2+ sensitivity, which alleviates the fatigue induced PLFFD.

Cigarette smoke directly impairs skeletal muscle function through capillary regression and altered myofibre calcium kinetics in mice.

KEY POINTS: Cigarette smoke components directly alter muscle fatigue resistance and intracellular muscle fibre Ca2+ handling independent of a change in lung structure. Changes in muscle vascular structure are associated with a depletion of satellite cells. Sarcoplasmic reticulum Ca2+ uptake is substantially impaired in myofibres during fatiguing contractions in mice treated with cigarette smoke extract. ABSTRACT: Cigarette smokers exhibit exercise intolerance before a decline in respiratory function. In the present study, the direct effects of cigarette smoke on limb muscle function were tested by comparing cigarette smoke delivered to mice by weekly injections of cigarette smoke extract (CSE), or nose-only exposure (CS) 5 days each week, for 8 weeks. Cigarette smoke delivered by either route did not alter pulmonary airspace size. Muscle fatigue measured in situ was 50% lower in the CSE and CS groups than in control. This was accompanied by 34% and 22% decreases in soleus capillary-to-fibre ratio of the CSE and CS groups, respectively, and a trend for fewer skeletal muscle actin-positive arterioles (P = 0.07). In addition, fewer quiescent satellite cells (Nes+Pax7+) were associated with soleus fibres in mice with skeletal myofibre VEGF gene deletion (decreased 47%) and CS exposed (decreased 73%) than with control fibres. Contractile properties of isolated extensor digitorum longus and soleus muscles were impaired. In flexor digitorum brevis myofibres isolated from CSE mice, fatigue resistance was diminished by 43% compared to control and CS myofibres, and this was accompanied by a pronounced slowing in relaxation, an increase in intracellular Ca2+ accumulation, and a slowing in sarcoplasmic reticulum Ca2+ uptake. These data suggest that cigarette smoke components may impair hindlimb muscle vascular structure, fatigue resistance and myofibre calcium handling, and these changes ultimately affect contractile efficiency of locomotor muscles independent of a change in lung function.

Balance between S-nitrosylation and denitrosylation modulates myoblast proliferation independently of soluble guanylyl cyclase activation.

Nitric oxide (NO) contributes to myogenesis by regulating the transition between myoblast proliferation and fusion through cGMP signaling. NO can form S-nitrosothiols (RSNO), which control signaling pathways in many different cell types. However, neither the role of RSNO content nor its regulation by the denitrosylase activity of S-nitrosoglutathione reductase (GSNOR) during myogenesis is understood. Here, we used primary cultures of chick embryonic skeletal muscle cells to investigate whether changes in intracellular RSNO alter proliferation and fusion of myoblasts in the presence and absence of cGMP. Cultures were grown to fuse most of the myoblasts into myotubes, with and without S-nitrosocysteine (CysNO), 8-Br-cGMP, DETA-NO, or inhibitors for NO synthase (NOS), GSNOR, soluble guanylyl cyclase (sGC), or a combination of these, followed by analysis of GSNOR activity, protein expression, RSNO, cGMP, and cell morphology. Although the activity of GSNOR increased progressively over 72 h, inhibiting GSNOR (by GSNOR inhibitor - GSNORi - or by knocking down GSNOR with siRNA) produced an increase in RSNO and in the number of myoblasts and fibroblasts, accompanied by a decrease in myoblast fusion index. This was also detected with CysNO supplementation. Enhanced myoblast number was proportional to GSNOR inhibition. Effects of the GSNORi and GSNOR knockdown were blunted by NOS inhibition, suggesting their dependence on NO synthesis. Interestingly, GSNORi and GSNOR knockdown reversed the attenuated proliferation obtained with sGC inhibition in myoblasts, but not in fibroblasts. Hence myoblast proliferation is enhanced by increasing RSNO, and regulated by GSNOR activity, independently of cGMP production and signaling.

Skeletal myofiber VEGF is essential for the exercise training response in adult mice.

Vascular endothelial growth factor (VEGF) is exercise responsive, pro-angiogenic, and expressed in several muscle cell types. We hypothesized that in adult mice, VEGF generated within skeletal myofibers (and not other cells within muscle) is necessary for the angiogenic response to exercise training. This was tested in adult conditional, skeletal myofiber-specific VEGF gene-deleted mice (skmVEGF-/-), with VEGF levels reduced by >80%. After 8 wk of daily treadmill training, speed and endurance were unaltered in skmVEGF-/- mice, but increased by 18% and 99% (P < 0.01), respectively, in controls trained at identical absolute speed, incline, and duration. In vitro, isolated soleus and extensor digitorum longus contractile function was not impaired in skmVEGF-/- mice. However, training-induced angiogenesis was inhibited in plantaris (wild type, 38%, skmVEGF-/- 18%, P < 0.01), and gastrocnemius (wild type, 43%, P < 0.01; skmVEGF-/-, 7%, not significant). Capillarity was maintained (different from VEGF gene deletion targeted to multiple cell types) in untrained skmVEGF-/- mice. Arteriogenesis (smooth muscle actin+, artery number, and diameter) and remodeling [vimentin+, 5'-bromodeoxycytidine (BrdU)+, and F4/80+ cells] occurred in skmVEGF-/- mice, even in the absence of training. skmVEGF-/- mice also displayed a limited oxidative enzyme [citrate synthase and ß-hydroxyacyl CoA dehydrogenase (ß-HAD)] training response; ß-HAD activity levels were elevated in the untrained state. These data suggest that myofiber expressed VEGF is necessary for training responses in capillarity and oxidative capacity and for improved running speed and endurance.

Oxygen-coupled redox regulation of the skeletal muscle ryanodine receptor-Ca2+ release channel by NADPH oxidase 4.

Physiological sensing of O(2) tension (partial O(2) pressure, pO(2)) plays an important role in some mammalian cellular systems, but striated muscle generally is not considered to be among them. Here we describe a molecular mechanism in skeletal muscle that acutely couples changes in pO(2) to altered calcium release through the ryanodine receptor-Ca(2+)-release channel (RyR1). Reactive oxygen species are generated in proportion to pO(2) by NADPH oxidase 4 (Nox4) in the sarcoplasmic reticulum, and the consequent oxidation of a small set of RyR1 cysteine thiols results in increased RyR1 activity and Ca(2+) release in isolated sarcoplasmic reticulum and in cultured myofibers and enhanced contractility of intact muscle. Thus, Nox4 is an O(2) sensor in skeletal muscle, and O(2)-coupled hydrogen peroxide production by Nox4 governs the redox state of regulatory RyR1 thiols and thereby governs muscle performance. These findings reveal a molecular mechanism for O(2)-based signaling by an NADPH oxidase and demonstrate a physiological role for oxidative modification of RyR1.

Ca²âº-pumping impairment during repetitive fatiguing contractions in single myofibers: role of cross-bridge cycling.

The energy cost of contractions in skeletal muscle involves activation of both actomyosin and sarcoplasmic reticulum (SR) Ca²âº-pump (SERCA) ATPases, which together determine the overall ATP demand. During repetitive contractions leading to fatigue, the relaxation rate and Ca²âº pumping become slowed, possibly because of intracellular metabolite accumulation. The role of the energy cost of cross-bridge cycling during contractile activity on Ca²âº-pumping properties has not been investigated. Therefore, we inhibited cross-bridge cycling by incubating isolated Xenopus single fibers with N-benzyl-p-toluene sulfonamide (BTS) to study the mechanisms by which SR Ca²âº pumping is impaired during fatiguing contractions. Fibers were stimulated in the absence (control) and presence of BTS and cytosolic calcium ([Ca²âº]c) transients or intracellular pH (pHi) changes were measured. BTS treatment allowed normal [Ca²âº]c transients during stimulation without cross-bridge activation. At the time point that tension was reduced to 50% in the control condition, the fall in the peak [Ca²âº]c and the increase in basal [Ca²âº]c did not occur with BTS incubation. The progressively slower Ca²âº pumping rate and the fall in pHi during repetitive contractions were reduced during BTS conditions. However, when mitochondrial ATP supply was blocked during contractions with BTS present (BTS + cyanide), there was no further slowing in SR Ca²âº pumping during contractions compared with the BTS-alone condition. Furthermore, the fall in pHi was significantly less during the BTS + cyanide condition than in the control conditions. These results demonstrate that factors related to the energetic cost of cross-bridge cycling, possibly the accumulation of metabolites, inhibit the Ca²âº pumping rate during fatiguing contractions.

Adaptation of the Quality of Communication Questionnaire for Family Members and Its Validity Evidence for Use in Brazil.

Assessment of communication between physicians and patients' family members is essential to improving healthcare quality. To adapt the Quality of Communication Questionnaire (QoC) for family members and to analyze its validity evidence for use in Brazil. Data were collected between 2017 and 2019, with family members of patients in intensive care (IC) and palliative care (PC) from five public hospitals in the South Brazil. The QoC was adapted for family members for use in Brazil, and its cross-cultural adaptation was carried out. The clarity and cultural appropriateness of the pre-final version were evaluated by 30 family members of patients in IC. The final version was responded by 198 family members of patients. All items were considered clear, and appropriate to Brazilian culture. The goodness of fit index for proposed model had CFI 0.96 (CI95%: 0.94 - 0.98), TLI 0.95 (CI95%: 0.92 - 0.97), RMSEA 0.07 (CI90%: 0.06 - 0.08), and χ2/df 2.18. Cronbach's alpha coefficient (α) among family members of patients in PC was 0.88 for the general communication (first subscale) and 0.80 for the end-of-life communication (second subscale). However, among family members of patients in IC, α was 0.86 for the first subscale and only 0.53 for the second subscale. The QoC for family members and its cross-cultural adaptation were carried out successfully. It has strong validity evidence among those with loved ones in PC, but only the QoC general communication subscale has strong validity evidence among those with loved ones in IC.

Applying the Generalizability Theory to Identify the Sources of Validity Evidence for the Quality of Communication Questionnaire.

Effective doctor-patient-family communication is an integral and sensitive part of health care, assessing its quality is essential to identify aspects needing disclosure and, if necessary, improvement. Cross-sectional study aimed to analyze the sources of evidence of validity and the number of participants needed to reliably apply the Quality of Communication Questionnaire (QoC) through Generalizability Theory (GT). The mean age of the 150 patients hospitalized at the end of life was 50.5 (SD = 13.8) years, the mean hospital length of stay was 7.5 (SD = 10.2) days, 56.9% were male. Regarding the 105 patients' family members of patients whose mean length of hospital stay was 9.5 (SD = 9.1) days, their mean age was 42.2 (SD = 14.7) years, 69.5% were female. GT was used to quantify the minimum number of questionnaires needed, with the aim of reaching a reliable estimate of QoC with G-coefficients. To reach a reliability of .90, there is a need for 25 for the Eρ2 questionnaires and 35 for the Φ. The exact estimation identified the minimum number of questionnaires required for the evaluation of physicians by patients. To obtain a reliability of .90, there is a need for 30 and 40 questionnaires for the G-coefficients. A practical and fast application makes it possible to use QoC in its entirety or alone to evaluate general communication or communication about palliative care. Furthermore, based on these results, it was possible to identify which aspects were effective or ineffective in these contexts.

Linking centennial scale anthropogenic changes and sedimentary records as lessons for urban coastal management.

Coastal eutrophication and urban flooding are increasingly important components of global change. Although increased seawater renewal by barrier openings and channelizing are common mitigation measures in coastal lagoons worldwide, their effects on these ecosystems are not fully understood. Here, we evaluated the relationships between human interventions in the watershed, artificial connections to the sea, and the sediment burial rates in an urban coastal lagoon (Maricá lagoon, Southeastern Brazil). Sediment accretion along with nutrient and carbon burial rates were determined in two sediment cores representing the past ∼120 years (210Pb dating) and associated with anthropogenic changes as indicated by historical records and geoinformation analyses. Lagoon infilling and eutrophication, expressed by the average sediment accretion, TP, TN, and OC burial rates, respectively, increased ∼9-18, 13-15, 11-14 and 11-12-fold from the earliest (<1950) to the most recent (2000-2017) period. These multi-proxy records confirm mechanistic links between deforestation, urbanization, and untreated sewage discharges. In addition, our findings reveal artificial connections to the sea may contribute to lagoonal eutrophication and infilling, particularly when not integrated with sewage treatment and forest conservation or reforestation in the watershed. Therefore, increased seawater renewal by physical interventions commonly considered as mitigation measures may in contrast cause severe degradation in coastal lagoons, causing harmful consequences that should be not neglected when implementing management practices.

Mitochondrial activation at the onset of contractions in isolated myofibres during successive contractile periods.

At the onset of skeletal muscle repetitive contractions, there is a significant delay in the time to achieve oxidative phosphorylation steady state. The purpose of the present study was to examine the factors that limit oxidative phosphorylation at the onset of contractions. NAD(P)H was measured in real time during two contractile periods (2 min each) separated by 5 min of rest in intact single muscle fibres (n = 7) isolated from Xenopus laevis. The fibres were then loaded with the dye tetramethylrhodamine methyl ester perchlorate (TMRM) to evaluate the kinetics of the mitochondrial membrane potential (Δψ (m)) during two further successive contractile periods. At the onset of contractions in the first period, NAD(P)H exhibited a time delay (14.1 ± 1.3 s) before decreasing toward a steady state. In contrast, Δψ(m) decreased immediately after the first contraction and started to be reestablished after 10.7 ± 0.9 s, with restoration to the pre-stimulation values after approximately 32 s. In the second contractile period (5 min after the first), NAD(P)H decreased immediately (i.e. no time delay) after the first contraction and had a significantly shorter time constant compared to the first contractile bout (3.3 ± 0.3 vs. 5.0 ± 0.2 s, P < 0.05). During the second bout, Δψ(m) remained unchanged from pre-stimulation values. These results suggest: (1) that at the onset of contractions, oxidative phosphorylation is primarily limited by the activity of the electron transport chain complexes rather than by a limited level of substrates; and (2) when the muscle is 'primed' by previous contractile activity, the faster enhancement of the cellular respiratory rate is due to intrinsic factors within the myofibre.

Stimulatory effects of the flavanol (-)-epicatechin on cardiac angiogenesis: additive effects with exercise.

The consumption of moderate amounts of cocoa products has been associated with reductions in the incidence of cardiovascular diseases. In animal studies, the flavanol (-)-epicatechin (Epi) yields cardioprotection. The effects may be partly due to its capacity to stimulate endothelial nitric oxide synthase (eNOS). The sustained activation of eNOS, as observed with exercise, can serve as a trigger of muscle angiogenesis via the activation of vascular endothelial growth factor (VEGF)-related events. Experiments were pursued to examine the potential of Epi to stimulate myocardial angiogenesis and determine the effects that its combined use with exercise (Ex) may trigger. Hearts obtained from a previous study were used for this purpose. Animals received 1 mg/kg of Epi or water (vehicle) via oral gavage (twice daily). Epi and/or Ex (by treadmill) was provided for 15 days. Results indicate that Ex or Epi significantly stimulate myocardial angiogenesis by ~30% above control levels. The use of Epi-Ex lead to further significant increases (to ~50%). Effects were associated with increases in protein levels and/or activation of canonical angiogenesis pathway associated events (HIF1a, VEGF, VEGFR2, PI3K, PDK, AKT, eNOS, NO, cGMP, MMP-2/-9, Src-1, and CD31). Thus, the use of Epi may represent a safe and novel means to stimulate myocardial angiogenesis.

Role of parvalbumin in fatigue-induced changes in force and cytosolic calcium transients in intact single mouse myofibers.

One of the most important cytosolic Ca2+ buffers present in mouse fast-twitch myofibers, but not in human myofibers, is parvalbumin (PV). Previous work using conventional PV gene (PV) knockout (PV-KO) mice suggests that lifelong PV ablation increases fatigue resistance, possibly due to compensations in mitochondrial volume. In this work, PV ablation was induced only in adult mice (PV-KO), and contractile and cytosolic Ca2+ responses during fatigue were studied in isolated muscle and intact single myofibers. Results were compared with control littermates (PV-Ctr). We hypothesized that the reduced myofiber cytosolic Ca2+ buffering developed only in adult PV-KO mice leads to a larger cytosolic free Ca2+ concentration ([Ca2+]c) during repetitive contractions, increasing myofiber fatigue resistance. Extensor digitorum longus (EDL) muscles from PV-KO mice had higher force in unfused stimulations (∼50%, P < 0.05) and slowed relaxation (∼46% higher relaxation time, P < 0.05) versus PV-Ctr, but muscle fatigue resistance or fatigue-induced changes in relaxation were not different between genotypes (P > 0.05). In intact single myofibers from flexor digitorum brevis (FDB) muscles, basal and tetanic [Ca2+]c during fatiguing contractions were higher in PV-KO (P < 0.05), accompanied by a greater slowing in estimated sarcoplasmic reticulum (SR) Ca2+-pumping versus PV-Ctr myofibers (∼84% reduction, P < 0.05), but myofiber fatigue resistance was not different between genotypes (P > 0.05). Our results demonstrate that although the estimated SR Ca2+ uptake was accelerated in PV-KO, the total energy demand by the major energy consumers in myofibers, the cross-bridges, and SR Ca2+ ATPase were not altered enough to affect the energy supply for contractions, and therefore fatigue resistance remained unaffected.NEW & NOTEWORTHY Parvalbumin (PV) is a cytosolic Ca2+ buffer that is present in mouse myofibers but not in human muscle. We show that inducible knockout of PV leads to increases in myofiber cytosolic free Ca2+ concentrations and slowing of Ca2+ pumping during fatigue versus control mice. However, PV ablation does not interfere with fatigue-induced slowing in relaxation or fatigue resistance. These data support the use of mouse muscle as a suitable model to investigate human muscle fatigue.