247 research outputs found

    In vitro Inhibitory Studies and Effect of Selected Plant Extracts and Cations on Elastase (EC 3.4.21.11) Activity produced by Aspergillus niger and Aspergillus flavus

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    Elastase is a member of the serine protease enzyme family that hydrolytically degrades elastin, a connective tissue component leading to aging and wrinkling of the skin. In this report, we investigated the in-vitro inhibitory effects of some cations and n-hexane extract of Hibiscus cannabinus, Vernonia amygdalina, Murraya koenigii, and Telfairia occidentalis on the activity of Elastase isolated from Aspergillus flavus and Aspergillus niger. Elastase was extracted, isolated and partially purified from Aspergillus flavus and Aspergillus niger. The data obtained in this study demonstrated that the activity of elastase in Aspergillus flavus was higher compared to that of Aspergillus niger after salting out. The elastase inhibition activities of Hibiscus cannabinus, Vernonia amygdalina, Murraya koenigii, and Telfairia occidentalis reveal that the leaf extract from Murraya koenigii, in Aspergillus flavus had more significant inhibition was obtained compared to that of Aspergillus niger, with inhibitory effect from 40µg/ml. While that of Hibiscus cannabinus showed similar inhibition characteristics to Murraya koenigii. Both Hibiscus cannabinus and Vernonia amygdalina had an effect at 80µg/ml; all the extracts appeared to have more effects on the enzyme obtained from Aspergillus flavus than from the Aspergillus niger. The potential of exploring these plant extract as an anti-aging recipe was discussed. Keywords: Inhibitory studies, Elastase, Aspergillus flavus, Aspergillus niger, Hibiscus cannabinus, Vernonia amygdalina, Murraya koenigii, and Telfairia occidentali

    Iridium-catalyzed C–H borylation of pyridines

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    The iridium-catalysed C–H borylation is a valuable and attractive method for the preparation of aryl and heteroaryl boronates. However, application of this methodology for the preparation of pyridyl and related azinyl boronates can be challenged by low reactivity and propensity for rapid protodeborylation, particularly for a boronate ester ortho to the azinyl nitrogen. Competition experiments have revealed that the low reactivity is due to inhibition of the active catalyst through coordination of the azinyl nitrogen lone pair at the vacant site on the iridium. This effect can be overcome through the incorporation of a substituent at C-2. Moreover, when this is sufficiently electron-withdrawing protodeborylation is sufficiently slowed to permit isolation and purification of the C-6 boronate ester. Following functionalization, reduction of the directing C-2 substituent provides the product arising from formal ortho borylation of an unhindered pyridine ring

    The Determination of alpha_s from Tau Decays Revisited

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    We revisit the determination of alpha_s(m_tau) using a fit to inclusive tau hadronic spectral moments in light of (1) the recent calculation of the fourth-order perturbative coefficient K_4 in the expansion of the Adler function, (2) new precision measurements from BABAR of e+e- annihilation cross sections, which decrease the uncertainty in the separation of vector and axial-vector spectral functions, and (3) improved results from BABAR and Belle on tau branching fractions involving kaons. We estimate that the fourth-order perturbative prediction reduces the theoretical uncertainty, introduced by the truncation of the series, by 20% with respect to earlier determinations. We discuss to some detail the perturbative prediction and show that the effect of the incomplete knowledge of the series is reduced by using the so-called contour-improved calculation, as opposed to fixed-order perturbation theory which manifests convergence problems. The corresponding theoretical uncertainties are studied at the tau and Z mass scales. Nonperturbative contributions extracted from the most inclusive fit are small, in agreement with earlier determinations. Systematic effects from quark-hadron duality violation are estimated with simple models and found to be within the quoted systematic errors. The fit gives alpha_s(m_tau) = 0.344 +- 0.005 +- 0.007, where the first error is experimental and the second theoretical. After evolution to M_Z we obtain alpha_s(M_Z) = 0.1212 +- 0.0005 +- 0.0008 +- 0.0005, where the errors are respectively experimental, theoretical and due to the evolution. The result is in agreement with the corresponding NNNLO value derived from essentially the Z width in the global electroweak fit. The alpha_s(M_Z) determination from tau decays is the most precise one to date.Comment: 22 pages, 7 figure

    Non-perturbative momentum dependence of the coupling constant and hadronic models

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    Models of hadron structure are associated with a hadronic scale which allows by perturbative evolution to calculate observables in the deep inelastic region. The resolution of Dyson-Schwinger equations leads to the freezing of the QCD running coupling (effective charge) in the infrared, which is best understood as a dynamical generation of a gluon mass function, giving rise to a momentum dependence which is free from infrared divergences. We use this new development to understand why perturbative treatments are working reasonably well despite the smallness of the hadronic scale.Comment: Changes in Acknowledgments and PACS number

    On the Behavior of the Effective QCD Coupling alpha_tau(s) at Low Scales

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    The hadronic decays of the tau lepton can be used to determine the effective charge alpha_tau(m^2_tau') for a hypothetical tau-lepton with mass in the range 0 < m_tau' < m_tau. This definition provides a fundamental definition of the QCD coupling at low mass scales. We study the behavior of alpha_tau at low mass scales directly from first principles and without any renormalization-scheme dependence by looking at the experimental data from the OPAL Collaboration. The results are consistent with the freezing of the physical coupling at mass scales s = m^2_tau' of order 1 GeV^2 with a magnitude alpha_tau ~ 0.9 +/- 0.1.Comment: 15 pages, 4 figures, submitted to Physical Review D, added references, some text added, no results nor figures change

    Randomised controlled trial to evaluate the effect of foot trimming before and after first calving on subsequent lameness episodes and productivity in dairy heifers

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    The objective of this study was to assess both independent and combined effects of routine foot trimming of heifers at 3 weeks pre-calving and 100 days post calving on the first lactation lameness and lactation productivity. A total of 419 pre-calving dairy heifers were recruited from one heifer rearing operation over a 10-month period. Heifers were randomly allocated into one of four foot trimming regimens; pre-calving foot trim and post-calving lameness score (Group TL), pre-calving lameness score and post-calving foot trim (Group LT), pre-calving foot trim and post-calving foot trim (Group TT), and pre-calving lameness score and post-calving lameness score (Group LL, control group). All heifers were scored for lameness at 24 biweekly time points for 1 year following calving, and first lactation milk production data were collected. Following calving, 172/419 (41.1%) of heifers became lame during the study (period prevalence), with lameness prevalence at each time-point following calving ranging from 48/392 (12.2%) at 29–42 days post-calving to 4/379 (1.1%) between 295 and 383 days after calving. The effects of the four treatment groups were not significantly different from each other for overall lameness period prevalence, biweekly lameness point prevalence, time to first lameness event, type of foot lesion identified at dry off claw trimming, or the 4% fat corrected 305-day milk yield. However, increased odds lameness was significantly associated with a pre-calving trim alone (P = 0.044) compared to the reference group LL. The odds of heifer lameness were highest between 0 and 6 weeks post-partum, and heifer farm destination was significantly associated with lameness (OR 2.24), suggesting that even at high standard facilities, environment and management systems have more effect on heifer foot health than trimming

    Renormalization Scheme Dependence and the Problem of Theoretical Uncertainties in Next-Next-to-Leading Order QCD Predictions

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    Renormalization scheme uncertainties in the next-next-to-leading order QCD predictions are discussed. To obtain an estimate of these uncertainties it is proposed to compare predictions in all schemes that do not have unnaturally large expansion coefficients. A concrete prescription for eliminating the unnatural schemes is given, based on the requirement that large cancellations in the expression for the characteristic renormalization scheme invariant should be avoided. As an example the QCD corrections to the Bjorken sum rule are considered. The importance of the next-next-to-leading order corrections for a proper evaluation of perturbative QCD predictions is emphasized.Comment: 15 pages, 3 figures,Late

    A genetic association study of glutamine-encoding DNA sequence structures, somatic CAG expansion, and DNA repair gene variants, with Huntington disease clinical outcomes

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    Background: Huntington disease (HD) is caused by an unstable CAG/CAA repeat expansion encoding a toxic polyglutamine tract. Here, we tested the hypotheses that HD outcomes are impacted by somatic expansion of, and polymorphisms within, the HTT CAG/CAA glutamine-encoding repeat, and DNA repair genes. Methods: The sequence of the glutamine-encoding repeat and the proportion of somatic CAG expansions in blood DNA from participants inheriting 40 to 50 CAG repeats within the TRACK-HD and Enroll-HD cohorts were determined using high-throughput ultra-deep-sequencing. Candidate gene polymorphisms were genotyped using kompetitive allele-specific PCR (KASP). Genotypic associations were assessed using time-to-event and regression analyses. Findings: Using data from 203 TRACK-HD and 531 Enroll-HD participants, we show that individuals with higher blood DNA somatic CAG repeat expansion scores have worse HD outcomes: a one-unit increase in somatic expansion score was associated with a Cox hazard ratio for motor onset of 3·05 (95% CI = 1·94 to 4·80, p = 1·3 × 10−6). We also show that individual-specific somatic expansion scores are associated with variants in FAN1 (pFDR = 4·8 × 10-6), MLH3 (pFDR = 8·0 × 10−4), MLH1 (pFDR = 0·004) and MSH3 (pFDR = 0·009). We also show that HD outcomes are best predicted by the number of pure CAGs rather than total encoded-glutamines. Interpretation: These data establish pure CAG length, rather than encoded-glutamine, as the key inherited determinant of downstream pathophysiology. These findings have implications for HD diagnostics, and support somatic expansion as a mechanistic link for genetic modifiers of clinical outcomes, a driver of disease, and potential therapeutic target in HD and related repeat expansion disorders

    Exploring bodily sensations experienced during flow states in professional national hunt jockeys: a connecting analysis

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    Previous research has suggested that distinct bodily sensations are experienced by athletes during flow states, and could represent a sport-specific characteristic of this phenomenon. This study aimed to enrich understanding about bodily sensations and flow states in sport by exploring this experience in national hunt jockeys. The interspecies nature of horse-rider partnerships accentuates the importance of bodily awareness in equestrian sports. Therefore, horse racing provided a fertile context in which to investigate bodily sensations experienced during flow states in sport. In-depth, semi-structured interviews exploring the experience of flow in horse racing were undertaken with 10 professional national hunt jockeys (M age = 28.1 years). Data were interpreted iteratively using inductive categorising/thematic and connecting analyses. Present findings suggested that flow states in jockeys produce an idiosyncratic and multifaceted sensory experience, and indicated that altered physical perceptions during flow were not restricted to kinaesthetic properties. Jockeys explained that distinct bodily sensations were experienced during flow states, and described alterations in their perceptions of kinaesthetic ‘feel’, balance, arousal and strength of touch. Each of these bodily sensations was discussed in relation to sensory information received from the horse, and a connecting analysis enlightened the factors underlying the realisation of these unique bodily sensations that accompanied flow states. Findings are discussed with respect to the existing literature on flow in sport and recommendations for future research are outlined. Further, possible considerations regarding the inclusion of bodily sensations as a characteristic of the flow experience in sport are outlined
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