After preparing composite PSGO films by coating electrospun polystyrene (PS) fibers with graphene oxide (GO), we examined their use as dye adsorbents for water remediation. The GO, which was ...synthesized via a modified Hummers' method, was adsorbed on the surface of the PS fibers. Through X-ray diffraction (XRD), Fourier Transform Infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and thermogravimetry (TGA) analyses, we characterized the structure and morphology of the composite films, confirming that the GO was successfully incorporated onto the PS fibers. SEM images revealed that the PS fibers exhibited a smooth surface and that the GO was uniformly deposited on them. TGA analysis indicated that the PSGO is composed of ∼13 wt% GO and ∼87 wt% PS, and that both components exhibited similar thermogravimetric behavior. We examined the removal of the methylene blue (MB) dye from aqueous solutions as a model system to assess the adsorptive properties of the PSGO films. The composite films had a removal capacity that was approximately 2.3 times greater than that of pure PS membranes. For all MB concentrations investigated, the removal of the dye, which was very fast in the first 30 min, the equilibrium value of the adsorption capacity (qe = 114 mg g−1) was reached after 120 min. The kinetics of the adsorption process was best described by the pseudo-second-order (PSO) model, which predicted an adsorption capacity (qt) of 116.69 mg g−1.
Display omitted
•Fabrication and use of electrospun polystyrene fiber covered with graphene oxide.•GO-coated polystyrene is a promising adsorbent of the Methylene Blue dye.•Outstanding adsorptive capacity in comparison to other reported adsorbents.
The objective of this study was to determine incidence and risk factors associated with spontaneous preterm birth (sPTB). It was a prospective multicentre cohort study performed in five Brazilian ...referral maternity hospitals and enrolling nulliparous women at 19-21 weeks. Comprehensive maternal data collected during three study visits were addressed as potentially associated factors for sPTB. Bivariate and multivariate analysis estimated risk ratios. The main outcomes measures were birth before 37 weeks due to spontaneous preterm labour or premature rupture of membranes (sPTB). The comparison group was comprised of women with term births (≥37weeks). Outcome data was available for 1,165 women, 6.7% of whom had sPTB, 16% had consumed alcohol and 5% had used other illicit drugs during the first half of pregnancy. Current drinking at 19-21 weeks (RR 3.96 95% CI 1.04-15.05) and a short cervix from 18-24 weeks (RR 4.52 95% CI 1.08-19.01) correlated with sPTB on bivariate analysis. Increased incidence of sPTB occurred in underweight women gaining weight below quartile 1 (14.8%), obese women gaining weight above quartile 3 (14.3%), women with a short cervix (<25 mm) at 18-24 weeks (31.2%) and those with a short cervix and vaginal bleeding in the first half of pregnancy (40%). Cervical length (RR
4.52 95% CI 1.08-19.01) was independently associated with sPTB. In conclusion, the incidence of sPTB increased in some maternal phenotypes, representing potential groups of interest, the focus of preventive strategies. Similarly, nulliparous women with a short cervix in the second trimester require further exploration.
Preterm birth is the major contributor for neonatal and under-five years mortality rates and also accounts for a short- and long-term adverse consequences up to adulthood. Perinatal outcomes may vary ...according to lots of factors as preterm subtype, late prematurity, which account for the vast majority of cases, country and population characteristics. An under-recognition of the perinatal outcomes and its associated factors might have underpowered strategies to provide adequate care and prevent its occurrence. We aim to estimate the frequency of maternal and perinatal outcomes in women with different categories of preterm and term births, factors associated with poorer perinatal outcomes and related management interventions. A multicentre prospective cohort in five maternities in Brazil between 2015 and 2018. Nulliparous low-risk women with singletons were included. Comprehensive data were collected during three antenatal visits (at 19-21weeks, 27-29 weeks and 37-39 weeks). Maternal and perinatal outcomes were also collected according to maternal and neonatal medical records. Women who had spontaneous (sPTB) and provider-initiated (pi-PTB) preterm birth were compared to those who had term birth. Also, late preterm birth (after 34 weeks), and early term (37-38 weeks) were compared to full term birth (39-40 weeks). Bivariate analysis estimated risk ratios for maternal and adverse outcomes. Finally, a multivariate analysis was conducted to address factors independently associated with any adverse perinatal outcome (APO). In total, 1,165 women had outcome data available, from which 6.7% had sPTB, 4.0% had pi-PTB and 89.3% had a term birth. sPTB and pi-PTb were associated with poorer perinatal outcomes, as well as late sPTB, late pi-PTB and early term neonates. pi-PTB (RR
8.12, 95% CI 2.54-25.93, p-value 0.007), maternal weight gain between 20 and 27 weeks <p10 (RR
2.04, 95% CI 1.23-3.38, p-value 0.018) and participants from the Northeast centres (RR
2.35, 95% CI 1.11-4.95, p-value 0.034) were independently associated with APO. According to our findings, Brazil would benefit from strategies to more accurately identify women at higher risk for PTB, to promote evidenced-based decision in preterm and early term provider-initiated deliveries, and to prevent perinatal adverse outcomes.
AMP-activated protein kinase (AMPK) and mammalian Target of Rapamycin (mTOR) are key regulators of cellular energy balance and of the effects of leptin on food intake. Acute exercise is associated ...with increased sensitivity to the effects of leptin on food intake in an IL-6-dependent manner. To determine whether exercise ameliorates the AMPK and mTOR response to leptin in the hypothalamus in an IL-6-dependent manner, rats performed two 3-h exercise bouts, separated by one 45-min rest period. Intracerebroventricular IL-6 infusion reduced food intake and pretreatment with AMPK activators and mTOR inhibitor prevented IL-6-induced anorexia. Activators of AMPK and fasting increased food intake in control rats to a greater extent than that observed in exercised ones, whereas inhibitor of AMPK had the opposite effect. Furthermore, the reduction of AMPK and ACC phosphorylation and increase in phosphorylation of proteins involved in mTOR signal transduction, observed in the hypothalamus after leptin infusion, were more pronounced in both lean and diet-induced obesity rats after acute exercise. Treatment with leptin reduced food intake in exercised rats that were pretreated with vehicle, although no increase in responsiveness to leptin-induced anorexia after pretreatment with anti-IL6 antibody, AICAR or Rapamycin was detected. Thus, the effects of leptin on the AMPK/mTOR pathway, potentiated by acute exercise, may contribute to appetite suppressive actions in the hypothalamus.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Biohybrid systems have been developed to better understand the design principles and coordination mechanisms of biological systems. We consider whether two functional regulatory features of the ...heart-mechanoelectrical signaling and automaticity-could be transferred to a synthetic analog of another fluid transport system: a swimming fish. By leveraging cardiac mechanoelectrical signaling, we recreated reciprocal contraction and relaxation in a muscular bilayer construct where each contraction occurs automatically as a response to the stretching of an antagonistic muscle pair. Further, to entrain this closed-loop actuation cycle, we engineered an electrically autonomous pacing node, which enhanced spontaneous contraction. The biohybrid fish equipped with intrinsic control strategies demonstrated self-sustained body-caudal fin swimming, highlighting the role of feedback mechanisms in muscular pumps such as the heart and muscles.
Department of Internal Medicine, School of Medicine, State University of Campinas, Campinas, SP, Brazil
Submitted 13 July 2004
; accepted in final form 9 May 2005
Focal adhesion kinase (FAK) has been ...shown to be activated in cardiac myocytes exposed to mechanical stress. However, details of how mechanical stimuli induce FAK activation are unknown. We investigated whether signaling events mediated by the RhoA/Rho-associated coiled coil-containing kinase (ROCK) pathway are involved in regulation of stretch-induced FAK phosphorylation at Tyr 397 in neonatal rat ventricular myocytes (NRVMs). Immunostaining showed that RhoA localized to regions of myofilaments alternated with phalloidin (actin) staining. The results of coimmunoprecipitation assays indicated that FAK and RhoA are associated in nonstretched NRVMs, but cyclic stretch significantly reduced the amount of RhoA recovered from anti-FAK immunoprecipitates. Cyclic stretch induced rapid and sustained (up to 2 h) increases in phosphorylation of FAK at Tyr 397 and ERK1/2 at Thr 202 /Tyr 204 . Blockade of RhoA/ROCK signaling by pharmacological inhibitors of RhoA ( Clostridium botulinum C3 exoenzyme) or ROCK (Y-27632, 10 µmol/l, 1 h) markedly attenuated stretch-induced FAK and ERK1/2 phosphorylation. Similar effects were observed in cells treated with the inhibitor of actin polymerization cytochalasin D. Transfection of NRVMs with RhoA antisense oligonucleotide attenuated stretch-induced FAK and ERK1/2 phosphorylation and expression of -myosin heavy chain mRNA. Similar results were seen in cells transfected with FAK antisense oligonucleotide. These findings demonstrate that RhoA/ROCK signaling plays a crucial role in stretch-induced FAK phosphorylation, presumably by coordinating upstream events operationally linked to the actin cytoskeleton.
mechanical stress; hypertrophy; cell signaling
Address for reprint requests and other correspondence: K. G. Franchini, Dept. de Clínica Médica, Faculdade de Ciências Médicas, Universidade Estadual de Campinas, Cidade Universitária "Zefferino Vaz," 13081-970 Campinas, SP, Brasil (e-mail: franchin{at}unicamp.br )
Display omitted
•The kinetics of moxidectin faeces excretion was evaluated in lambs.•Moxidectin (MOX) shows a long lasting excretion profile through the faeces.•MOX shows large persistence under ...Brazilian subtropical environmental conditions.•A throughput method for determining MOX residues in lamb faeces is reported.
The faecal excretion profile of moxidectin (MOX) was evaluated in Suffolk lambs (n = 7) with mean body weight (BW) of 36.06 ± 3.23, using a completely randomized experimental design. The animals received a single subcutaneous dose of 0.2 mg/kg BW. Faecal samples were collected 6, 12, 18, 24, 30 and 36 h (h), and 5, 9, 14, 21, 28, 35 and 42 days after the application of MOX. The samples were analyzed by liquid chromatography tandem mass spectrometry (LC–MS/MS QqQ). The method was validated showing 85.4–111.8% recovery and intra-day and inter-days precision values between 6.2 and 9.4%. The method limit of quantitation (LOQ) was 5.0 ng/g. The MOX showed a large excretion through the lamb faeces, with a maximum concentration (Cmax) of 22.73 ng/g at a time (Tmax) of 39.92 h. The area under the curve (AUC) value was 13,292 ng h/g. Subsequently, the persistence of MOX residues in the faeces exposed to the environment was assessed using a randomized complete block design. For this purpose, thirteen Suffolk and Dorper rams, with BW of 76.43 ± 34.24 kg, were separated into two groups: control and MOX treated. Their faeces were collected in bags at Tmax after MOX application of a subcutaneous single dose of 0.2 mg/kg BW, and were exposed to the environment. At 88th day, the MOX concentrations in the dry faeces were 29.22 ± 5.31 ng/g and 28.07 ± 5.90 ng/g whereas the initial mean concentrations were 35.94 ± 2.96 and 38.49 ± 4.71 ng/g dry faeces, with or without protection against rain, respectively. Thus, the use of rain cover to protect the faeces during exposure to the environment did not affect the residual MOX concentration in the dung. However, since the loss of faecal dry matter was higher from the faeces without cover the migration of MOX to the environment was also higher from the faeces when exposed to the environment without cover (27.08%) than with cover (18.69%). The large excretion of MOX and its sorption by the faeces and high persistence in the environment indicate that risk management actions should be taken by all the stakeholders (veterinary drug industry, farmers and government) to minimize the environmental impact of MOX on the soil fauna population in sheep production systems.
The production of conductive and organic devices from a 3D printer represents a promising strategy for several areas. In particular, the synthesis of polypyrrole-coated acrylonitrile butadiene ...styrene (ABS) composites can be considered an important step to produce conductive supports for 3D printing. Herein, it is reported the production of ABS samples through the additive manufacturing process (3D printing) accordingly to the Fused Deposition Modeling (FDM) method. The hydrophilic behavior was controlled by the surface treatment using air plasma for the following step of coating with polypyrrole (PPy) via an in situ polymerization, using two different oxidants: ferric chloride (FeCl3.6H2O) and ammonium persulfate (APS). The chemical, optical, surface, and electrical properties of these materials were characterized through Fourier Transform infrared spectroscopy (FTIR), contact angle measurements, cyclic voltammetry, Scanning Electron Microscopy (SEM), 4-probe electrical measurement, and mechanical tensile testing. The ABS/PPy (FeCl3) composite exhibited a low electrical contact resistance and better performance for applications that require electrodes with a good conductance level.
Department of Physiology, University of Bern, Switzerland; and the Cardiac Bioelectricity Research and Training Center, Departments of Biomedical Engineering, Physiology and Biophysics, and Medicine, ...Case Western Reserve University, Cleveland, Ohio
Kléber, André G., and Yoram Rudy. Basic Mechanisms of Cardiac Impulse Propagation and Associated Arrhythmias. Physiol Rev 84: 431488, 2004; 10.1152/physrev.00025.2003.Propagation of excitation in the heart involves action potential (AP) generation by cardiac cells and its propagation in the multicellular tissue. AP conduction is the outcome of complex interactions between cellular electrical activity, electrical cell-to-cell communication, and the cardiac tissue structure. As shown in this review, strong interactions occur among these determinants of electrical impulse propagation. A special form of conduction that underlies many cardiac arrhythmias involves circulating excitation. In this situation, the curvature of the propagating excitation wavefront and the interaction of the wavefront with the repolarization tail of the preceding wave are additional important determinants of impulse propagation. This review attempts to synthesize results from computer simulations and experimental preparations to define mechanisms and biophysical principles that govern normal and abnormal conduction in the heart.
Address for reprint requests and other correspondence: A. G. Kléber, Dept. of Physiology, Univ. of Bern, Bühlplatz 5, CH-3012 Bern, Switzerland (E-mail: kleber{at}pyl.unibe.ch ).
The activation of the members of the myocyte enhancer factor-2 family (MEF2A, B, C and D) of transcription factors promotes cardiac hypertrophy and failure. However, the role of its individual ...components in the pathogenesis of cardiac hypertrophy remains unclear.
In this study, we investigated whether MEF2C plays a role in mediating the left ventricular hypertrophy by pressure overload in mice. The knockdown of myocardial MEF2C induced by specific small interfering RNA (siRNA) has been shown to attenuate hypertrophy, interstitial fibrosis and the rise of ANP levels in aortic banded mice. We detected that the depletion of MEF2C also results in lowered levels of both PGC-1alpha and mitochondrial DNA in the overloaded left ventricle, associated with enhanced AMP:ATP ratio. Additionally, MEF2C depletion was accompanied by defective activation of S6K in response to pressure overload. Treatment with the amino acid leucine stimulated S6K and suppressed the attenuation of left ventricular hypertrophy and fibrosis in the aforementioned aortic banded mice.
These findings represent new evidences that MEF2C depletion attenuates the hypertrophic responses to mechanical stress and highlight the potential of MEF2C to be a target for new therapies to cardiac hypertrophy and failure.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
PDF
