Orthogonal protection of peptides and peptoids for cyclization by the thiol-ene reaction and conjugation

Cyclic peptides and peptoids were prepared using the thiol-ene Michael-type reaction. The linear precursors were provided with additional functional groups allowing for subsequent conjugation: an orthogonally protected thiol, a protected maleimide, or an alkyne. The functional group for conjugation was placed either within the cycle or in an external position. The click reactions employed for conjugation with suitably derivatized nucleoside or oligonucleotides were either cycloadditions (Diels-Alder, Cu(I)-catalyzed azide-alkyne) or the same Michael-type reaction as for cyclization

Straightforward synthesis of cyclic and bicyclic peptides

Cyclic peptide architectures can be easily synthesized from cysteine-containing peptides with appending maleimides, free or protected, through an intramolecular Michael-type reaction. After peptide assembly, the peptide can cyclize either during the trifluoroacetic acid treatment, if the maleimide is not protected, or upon deprotection of the maleimide. The combination of free and protected maleimide moieties and two orthogonally protected cysteines gives access to structurally different bicyclic peptides with isolated or fused cycles

Modelling beef meat quality traits during ageing by early post-mortem pH decay descriptors

Previous work has demonstrated that beef carcasses can be promptly and accurately classified into optimal quality and cold-shortened in accordance to the concept of pH/temperature ‘ideal window’ by using carcass characteristics and early post-mortem pH/temperature decay descriptors. The objective of this study was to assess the combined effects of the aforementioned variables on the two main eating quality attributes of meat – namely, tenderness (measured as shear force) and juiciness (measured as cooking loss) – during chill ageing. The pH and temperature in longissimus thoracis muscle of 51 beef carcasses were recorded during 24 h post-mortem, and decay descriptors were then obtained by fitting exponential models. Measures of Warner-Bratzler shear force and cooking loss were obtained from cooked meat after 3, 8 and 13 days of cold ageing. The fitted mixed-effect models revealed that both meat tenderisation and cooking loss increased with ageing (P<0.01) although their rates slowed down in time (P<0.05). Beef carcasses with a higher pH (obtained at different endpoints: 1.5, 3.0, 4.5 or 6.0 h post-mortem) produced aged meat with increased tenderness (P=0.013) and increased water retention during cooking (P=0.016) than those of lower pH. Nonetheless, the slower the pH decay rate, as happens in a cold-shortened carcass, the lower the potential for tenderisation (P=0.038) and water retention (P=0.050) during ageing. Whereas sex affected shear force, with females producing meat of higher tenderness, aged meat of increased water retention was produced by heavier beef carcasses (P<0.001). The good fitting quality of the shear force (R2=0.847) and cooking loss (R2=0.882) models and their similarity among the different endpoints post-mortem indicated that both eating quality attributes can be approached by recording the pH decline of a beef carcass during the first 3.0 hours after slaughter.info:eu-repo/semantics/publishedVersio

Association between pesticide exposure and suicide rates in Brazil

AbstractIntroductionThe association between pesticide use and an increased suicide risk is a controversial issue. Previous studies have shown higher rates of suicide among agricultural workers and people living in small municipalities, but have not identified the causes of these results.ObjectiveTo investigate the association between pesticide exposure and suicide rates.MethodsCrude suicide rates of a 15-year time series (1996–2010) were examined, followed by an ecological study using age-standardized suicide rates for the period 2006–2010. The unit of analysis was all 558 Brazilian micro-regions. Pesticide exposure was evaluated according to the proportion of farms that used pesticides and had reported cases of pesticide poisonings. The statistics were analysed using Pearson's correlation and multiple linear regression adjusted for socioeconomic, demographic and cultural factors.ResultsAmong the age group that was analysed, the mean suicide rate was 6.4 cases/100,000 per year in the 2006–2010 period, with a male/female ratio of 4.2. The times series showed that there were higher suicide rates among people aged 35–64 years and among men aged 15–34 years. The ecological analysis showed that the suicide rates were higher in micro-regions with a higher proportion of farms run by 35–64 year olds, female workers and on farms with better economic indicators (higher farming income, level of mechanization and farm area). There was a positive association between the Catholic religion and suicide rates. Micro-regions with a greater use of pesticides, and with a high proportion of pesticide poisoning had the highest suicide rates for all three groups analysed: both genders, men, and women (p ranging from 0.01 to p<0.001).ConclusionThis study reinforces the hypothesis that pesticide use and pesticide poisoning increase the suicide rates. However, due to the limitations of the study's ecological design, such as ecological fallacy, further appropriately designed studies are needed to confirm the causal relationships

Prevalência de dor lombar crônica: revisão sistemática

OBJECTIVE To estimate worldwide prevalence of chronic low back pain according to age and sex. METHODS We consulted Medline (PubMed), LILACS and EMBASE electronic databases. The search strategy used the following descriptors and combinations: back pain, prevalence, musculoskeletal diseases, chronic musculoskeletal pain, rheumatic, low back pain, musculoskeletal disorders and chronic low back pain. We selected cross-sectional population-based or cohort studies that assessed chronic low back pain as an outcome. We also assessed the quality of the selected studies as well as the chronic low back pain prevalence according to age and sex. RESULTS The review included 28 studies. Based on our qualitative evaluation, around one third of the studies had low scores, mainly due to high non-response rates. Chronic low back pain prevalence was 4.2% in individuals aged between 24 and 39 years old and 19.6% in those aged between 20 and 59. Of nine studies with individuals aged 18 and above, six reported chronic low back pain between 3.9% and 10.2% and three, prevalence between 13.1% and 20.3%. In the Brazilian older population, chronic low back pain prevalence was 25.4%. CONCLUSIONS Chronic low back pain prevalence increases linearly from the third decade of life on, until the 60 years of age, being more prevalent in women. Methodological approaches aiming to reduce high heterogeneity in case definitions of chronic low back pain are essential to consistency and comparative analysis between studies. A standard chronic low back pain definition should include the precise description of the anatomical area, pain duration and limitation level.OBJETIVO Estimar a prevalência mundial de dor lombar crônica, segundo idade e sexo. MÉTODOS Foram consultadas as bases de dados eletrônicas Medline (PubMed), Lilacs e Embase. A estratégia de busca utilizou os seguintes descritores:back pain, prevalence,musculoskeletal diseases,chronic musculoskeletal pain,rheumatic,low back pain,musculoskeletal disorders e chronic low back pain . Foram selecionados os estudos de base populacional de delineamento transversal ou coortes que avaliaram dor lombar crônica como desfecho. A qualidade dos estudos selecionados foi avaliada, assim como a prevalência de dor lombar crônica, segundo idade e sexo. RESULTADOS Foram incluídos 28 estudos nesta revisão. De acordo com a avaliação qualitativa, cerca de um terço dos estudos tiveram pontuação baixa, principalmente em decorrência das altas taxas de não respondentes. A prevalência de dor lombar crônica foi de 4,2% em indivíduos com idade entre 24 e 39 anos e 19,6% entre aqueles de 20 a 59 anos. Dentre nove estudos com indivíduos com 18 anos ou mais, em seis a prevalência de dor lombar crônica variou entre 3,9% a 10,2%, e nos outros três estudos a prevalência foi entre 13,1% e 20,3%. Entre idosos brasileiros, a prevalência de dor lombar crônica foi de 25,4%. CONCLUSÕES A prevalência de dor lombar crônica aumenta linearmente a partir da terceira década de vida até os 60 anos de idade, sendo mais prevalente nas mulheres. Questões metodológicas visando a reduzir a alta heterogeneidade nas definições de casos nos estudos sobre dor lombar crônica são fundamentais para permitir análises comparativas e de consistência entre diferentes estudos. A definição de dor lombar crônica deve incluir a descrição precisa da área anatômica, período de duração da dor e nível de limitação

Experimental polarization encoded quantum key distribution over optical fibres with real-time continuous birefringence compensation

In this paper we demonstrate an active polarization drift compensation scheme for optical fibres employed in a quantum key distribution experiment with polarization encoded qubits. The quantum signals are wavelength multiplexed in one fibre along with two classical optical side channels that provide the control information for the polarization compensation scheme. This set-up allows us to continuously track any polarization change without the need to interrupt the key exchange. The results obtained show that fast polarization rotations of the order of 40*pi rad/s are effectively compensated for. We demonstrate that our set-up allows continuous quantum key distribution even in a fibre stressed by random polarization fluctuations. Our results pave the way for Bell-state measurements using only linear optics with parties separated by long-distance optical fibres

Deep Self-Taught Learning for Handwritten Character Recognition

Recent theoretical and empirical work in statistical machine learning has demonstrated the importance of learning algorithms for deep architectures, i.e., function classes obtained by composing multiple non-linear transformations. Self-taught learning (exploiting unlabeled examples or examples from other distributions) has already been applied to deep learners, but mostly to show the advantage of unlabeled examples. Here we explore the advantage brought by {\em out-of-distribution examples}. For this purpose we developed a powerful generator of stochastic variations and noise processes for character images, including not only affine transformations but also slant, local elastic deformations, changes in thickness, background images, grey level changes, contrast, occlusion, and various types of noise. The out-of-distribution examples are obtained from these highly distorted images or by including examples of object classes different from those in the target test set. We show that {\em deep learners benefit more from out-of-distribution examples than a corresponding shallow learner}, at least in the area of handwritten character recognition. In fact, we show that they beat previously published results and reach human-level performance on both handwritten digit classification and 62-class handwritten character recognition