842 research outputs found
Enzymatic degradation of starch thermoplastic blends using samples of different thickness
The material studied was a thermoplastic blend of corn starch with a poly(ethylene-vinyl alcohol) copolymer, SEVA-C. The influence of both the material’s exposed surface and enzyme concentration on degradation kinetics was studied. As α-amylase is present in the blood plasma, experiments were performed, varying the material thickness and the α-amylase between 50 and 100 units/l, at 37°C, lasting up to 90 days. Four different batches using SEVA-C and starch samples of different thickness were performed. The positive correlation between degradation rate and the exposed material surface was confirmed, since thin films with larger exposed surfaces were degraded faster than thick square plates having the same total mass. The degradation extent depends on the total amount of amorphous starch present in the formulation rather than on the amount of enzyme used and the minimum thickness to ensure maximum degradation was estimated to be close to 0.25 mm
Reproductive Performance of Dairy Cows Affected by Endometritis, Pododermatitis and Mastitis
The effects of endometritis, pododermatitis and clinical mastitis on the conception rate and calving-conception interval of multiparous and primiparous cows after fixed-time artificial insemination (FTAI) were evaluated. Clinical endometritis was diagnosed by ultrasonography 20-40 days postpartum upon observation of fluid in the uterine lumen. Cows with clinical endometritis were treated intramuscularly with 2 mg/kg ceftiofur hydrochloride over three consecutive days. Forty-five days after delivery, multiparous and primiparous cows with normal uteri according to ultrasonography were selected for the study, filed and inseminated by FTAI. To identify animals with hoof problems and clinical mastitis and to define their respective groups, the cows were observed daily during morning and nightly milking for up to 60 days after FTAI, and animals with hoof lesions were treated. Animals with clinical mastitis were treated with intramammary infusion containing 88 mg cefquinome sulphate every 12 h after milking for four days. The conception rate of multiparous cows with clinical endometritis at 30 and 60 days after FTAI was negatively affected compared with that of healthy cows with pododermatitis. However, clinical endometritis did not influence the primiparous category, whereas pododermatitis and clinical mastitis did not influence the conception rate of any category at 30 and 60 days after FTAI. Differences were not observed between primiparous or multiparous cows in the calving-conception interval. Keywords: Lactation, Pregnancy, Health, Fertilit
Search for direct pair production of the top squark in all-hadronic final states in proton-proton collisions at s√=8 TeV with the ATLAS detector
The results of a search for direct pair production of the scalar partner to the top quark using an integrated luminosity of 20.1fb−1 of proton–proton collision data at √s = 8 TeV recorded with the ATLAS detector at the LHC are reported. The top squark is assumed to decay via t˜→tχ˜01 or t˜→ bχ˜±1 →bW(∗)χ˜01 , where χ˜01 (χ˜±1 ) denotes the lightest neutralino (chargino) in supersymmetric models. The search targets a fully-hadronic final state in events with four or more jets and large missing transverse momentum. No significant excess over the Standard Model background prediction is observed, and exclusion limits are reported in terms of the top squark and neutralino masses and as a function of the branching fraction of t˜ → tχ˜01 . For a branching fraction of 100%, top squark masses in the range 270–645 GeV are excluded for χ˜01 masses below 30 GeV. For a branching fraction of 50% to either t˜ → tχ˜01 or t˜ → bχ˜±1 , and assuming the χ˜±1 mass to be twice the χ˜01 mass, top squark masses in the range 250–550 GeV are excluded for χ˜01 masses below 60 GeV
Endothelial cells enhance the in vivo bone-forming ability of osteogenic cell sheets
Addressing the problem of vascularization is of vital importance when engineering three-dimensional (3D) tissues. Endothelial cells are increasingly used in tissue-engineered constructs to obtain prevascularization and to enhance in vivo neovascularization. Rat bone marrow stromal cells were cultured in thermoresponsive dishes under osteogenic conditions with human umbilical vein endothelial cells (HUVECs) to obtain homotypic or heterotypic cell sheets (CSs). Cells were retrieved as sheets from the dishes after incubation at 20 °C. Monoculture osteogenic CSs were stacked on top of homotypic or heterotypic CSs, and subcutaneously implanted in the dorsal flap of nude mice for 7 days. The implants showed mineralized tissue formation under both conditions. Transplanted osteogenic cells were found at the new tissue site, demonstrating CS bone-inductive effect. Perfused vessels, positive for human CD31, confirmed the contribution of HUVECs for the neovascularization of coculture CS constructs. Furthermore, calcium quantification and expression of osteocalcin and osterix genes were higher for the CS constructs, with HUVECs demonstrating the more robust osteogenic potential of these constructs. This work demonstrates the potential of using endothelial cells, combined with osteogenic CSs, to increase the in vivo vascularization of CS-based 3D constructs for bone tissue engineering purposes.We would like to acknowledge Mariana T Cerqueira for the illustration in Figure 1. This study was supported by Formation of Innovation Center for Fusion of Advanced Technologies in the Special Coordination Funds for Promoting Science and Technology 'Cell Sheet Tissue Engineering Center (CSTEC)' and the Global CUE program, the Multidisciplinary Education and Research Center for Regenerative Medicine (MERCREM), from the Ministry of Education, Culture, Sports, Science and Technology (MEXT), Japan. Financial support to RP Pirraco by the Portuguese Foundation for Science and Technology (FCT) through the PhD Grant SFRH/BD/44893/2008 is also acknowledged
Bone mineral density in vocational and professional ballet dancers
Summary: According to existing literature, bone health in ballet dancers is controversial. We have verified that, compared to controls, young female and male vocational ballet dancers have lower bone mineral density (BMD) at both impact and non-impact sites, whereas female professional ballet dancers have lower BMD only at non-impact sites.
Introduction: The aims of this study were to (a) assess bone mineral density (BMD) in vocational (VBD) and professional (PBD) ballet dancers and (b) investigate its association with body mass (BM), fat mass (FM), lean mass (LM), maturation and menarche.
Methods: The total of 152 VBD (13 ± 2.3 years; 112 girls, 40 boys) and 96 controls (14 ± 2.1 years; 56 girls, 40 boys) and 184 PBD (28 ± 8.5 years; 129 females, 55 males) and 160 controls (27 ± 9.5 years; 110 female, 50 males) were assessed at the lumbar spine (LS), femoral neck (FN), forearm and total body by dual-energy X-ray absorptiometry. Maturation and menarche were assessed via questionnaires.
Results: VBD revealed lower unadjusted BMD at all anatomical sites compared to controls (p < 0.001); following adjustments for Tanner stage and gynaecological age, female VBD showed similar BMD values at impact sites. However, no factors were found to explain the lower adjusted BMD values in VBD (female and male) at the forearm (non-impact site), nor for the lower adjusted BMD values in male VBD at the FN. Compared to controls, female PBD showed higher unadjusted and adjusted BMD for potential associated factors at the FN (impact site) (p < 0.001) and lower adjusted at the forearm (p < 0.001). Male PBD did not reveal lower BMD than controls at any site.
Conclusions: both females and males VBD have lower BMD at impact and non-impact sites compared to control, whereas this is only the case at non-impact site in female PBD. Maturation seems to explain the lower BMD at impact sites in female VBD
Astrocyte pathology in the prefrontal cortex impairs the cognitive function of rats
Interest in astroglial cells is rising due to recent findings supporting dynamic neuron-astrocyte interactions. There is increasing evidence of astrocytic dysfunction in several brain disorders such as depression, schizophrenia or bipolar disorder; importantly these pathologies are characterized by the involvement of the prefrontal cortex and by significant cognitive impairments. Here, to model astrocyte pathology, we injected animals with the astrocyte specific toxin L-a-aminoadipate (L-AA) in the medial prefrontal cortex (mPFC); a behavioral and structural characterization two and six days after the injection was performed. Behavioral data shows that the astrocyte pathology in the mPFC affects the attentional set-shifting, the working memory and the reversal learning functions. Histological analysis of brain sections of the L-AA-injected animals revealed a pronounced loss of astrocytes in the targeted region. Interestingly, analysis of neurons in the lesion sites showed a progressive neuronal loss that was accompanied with dendritic atrophy in the surviving neurons. These results suggest that the L-AA-induced astrocytic loss in the mPFC triggers subsequent neuronal damage leading to cognitive impairment in tasks depending on the integrity of this brain region. These findings are of relevance to better understand the pathophysiological mechanisms underlying disorders that involve astrocytic loss/dysfunction in the PFC.This work was supported by the Marie Curie Fellowship FP7-PEOPLE-2010-IEF 273936, BIAL Foundation Grants 138/2008 and 61/2010, FEDER funds through Operational program for competitiveness factors-COMPETE -, ON2 Programa Operacional Regional do Norte (ON.2-O Novo Norte), QREN/FEDER, and by national funds through FCT-Foundation for Science and Technology-project (PTDC/SAU-NSC/118194/2010) and fellowships (SFRH/BPD/66151/2009 and SFRH/BD/89714/2012)
Sedentary behaviour is associated with increased long-term cardiovascular risk in patients with rheumatoid arthritis independently of moderate-to-vigorous physical activity
Background Rheumatoid Arthritis (RA) is associated with an increased risk of cardiovascular disease (CVD). The physical dysfunction symptomatic of RA means people living with this disease spend large periods of the day sedentary, which may further elevate their risk of CVD. The primary aim of this study was to investigate relationships between objectively assessed sedentary behaviour patterns and light physical activity (LPA) with 10-year risk of CVD. Secondary aims were to explore the role of sedentary behaviour patterns and LPA for individual CVD risk factors and functional disability in RA. The extent to which associations were independent of moderate-to-vigorous physical activity (MVPA) engagement was also examined. Methods Baseline data from a subsample of participants recruited to the Physical Activity in Rheumatoid Arthritis (PARA) study were used to answer current research questions. Sixty-one patients with RA (mean age (± SD) = 54.92 ± 12.39 years) provided a fasted blood sample and underwent physical assessments to evaluate factors associated with their cardiovascular health. Sedentary behaviour patterns (sedentary time, sedentary bouts, sedentary breaks), LPA and MVPA were measured via 7-days of accelerometry. Ten-year CVD risk was computed (Q-risk-score2), and functional disability determined via questionnaire. Results Regressions revealed significant positive associations between sedentary time and the number of sedentary bouts per day ≥20 min with 10-year CVD risk, with the reverse true for LPA participation. Associations were independent of MVPA engagement. Conclusions Promoting LPA participation and restricting sedentary bouts to <20 min may attenuate long-term CVD risk in RA, independent of MVPA engagement
Complement system activation contributes to the ependymal damage induced by microbial neuraminidase
Background
In the rat brain, a single intracerebroventricular injection of neuraminidase from Clostridium perfringens induces ependymal detachment and death. This injury occurs before the infiltration of inflammatory blood cells; some reports implicate the complement system as a cause of these injuries. Here, we set out to test the role of complement.
Methods
The assembly of the complement membrane attack complex on the ependymal epithelium of rats injected with neuraminidase was analyzed by immunohistochemistry. Complement activation, triggered by neuraminidase, and the participation of different activation pathways were analyzed by Western blot. In vitro studies used primary cultures of ependymal cells and explants of the septal ventricular wall. In these models, ependymal cells were exposed to neuraminidase in the presence or absence of complement, and their viability was assessed by observing beating of cilia or by trypan blue staining. The role of complement in ependymal damage induced by neuraminidase was analyzed in vivo in two rat models of complement blockade: systemic inhibition of C5 by using a function blocking antibody and testing in C6-deficient rats.
Results
The complement membrane attack complex immunolocalized on the ependymal surface in rats injected intracerebroventricularly with neuraminidase. C3 activation fragments were found in serum and cerebrospinal fluid of rats treated with neuraminidase, suggesting that neuraminidase itself activates complement. In ventricular wall explants and isolated ependymal cells, treatment with neuraminidase alone induced ependymal cell death; however, the addition of complement caused increased cell death and disorganization of the ependymal epithelium. In rats treated with anti-C5 and in C6-deficient rats, intracerebroventricular injection of neuraminidase provoked reduced ependymal alterations compared to non-treated or control rats. Immunohistochemistry confirmed the absence of membrane attack complex on the ependymal surfaces of neuraminidase-exposed rats treated with anti-C5 or deficient in C6.
Conclusions
These results demonstrate that the complement system contributes to ependymal damage and death caused by neuraminidase. However, neuraminidase alone can induce moderate ependymal damage without the aid of complement
Absence of N-terminal acetyltransferase diversification during evolution of eukaryotic organisms
Protein N-terminal acetylation is an ancient and ubiquitous co-translational modification catalyzed by a highly conserved family of N-terminal acetyltransferases (NATs). Prokaryotes have at least 3 NATs, whereas humans have six distinct but highly conserved NATs, suggesting an increase in regulatory complexity of this modification during eukaryotic evolution. Despite this, and against our initial expectations, we determined that NAT diversification did not occur in the eukaryotes, as all six major human NATs were most likely present in the Last Eukaryotic Common Ancestor (LECA). Furthermore, we also observed that some NATs were actually secondarily lost during evolution of major eukaryotic lineages; therefore, the increased complexity of the higher eukaryotic proteome occurred without a concomitant diversification of NAT complexes
Effectiveness and Cost-effectiveness of Outpatient Physiotherapy After Knee Replacement for Osteoarthritis: Study Protocol for a Randomised Controlled Trial
Background: Primary total knee replacement is a common operation that is performed to provide pain relief and restore functional ability. Inpatient physiotherapy is routinely provided after surgery to enhance recovery prior to hospital discharge. However, international variation exists in the provision of outpatient physiotherapy after hospital discharge. While evidence indicates that outpatient physiotherapy can improve short-term function, the longer term benefits are unknown. The aim of this randomised controlled trial is to evaluate the long-term clinical effectiveness and cost-effectiveness of a 6-week group-based outpatient physiotherapy intervention following knee replacement.
Methods/design: Two hundred and fifty-six patients waiting for knee replacement because of osteoarthritis will be recruited from two orthopaedic centres. Participants randomised to the usual-care group (n = 128) will be given a booklet about exercise and referred for physiotherapy if deemed appropriate by the clinical care team. The intervention group (n = 128) will receive the same usual care and additionally be invited to attend a group-based outpatient physiotherapy class starting 6 weeks after surgery. The 1-hour class will be run on a weekly basis over
6 weeks and will involve task-orientated and individualised exercises.
The primary outcome will be the Lower Extremity Functional Scale at 12 months post-operative. Secondary outcomes include: quality of life, knee pain and function, depression, anxiety and satisfaction. Data collection will be by questionnaire prior to surgery and 3, 6 and 12 months after surgery and will include a resource-use questionnaire to enable a trial-based economic evaluation. Trial participation and satisfaction with the classes will be evaluated through structured telephone interviews. The primary statistical and economic analyses will be conducted on an intention-to-treat basis with and without imputation of missing data. The primary economic result will estimate the incremental cost per quality-adjusted life year gained from this intervention from a National Health Services (NHS) and personal social services perspective.
Discussion: This research aims to benefit patients and the NHS by providing evidence on the long-term effectiveness and cost-effectiveness of outpatient physiotherapy after knee replacement. If the intervention is found to be effective and cost-effective, implementation into clinical practice could lead to improvement in patients’ outcomes and improved health care resource efficiency
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