3,725 research outputs found

    1,5-asymmetric induction in the boron-mediated aldol reactions of beta-oxygenated methyl ketones

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    High levels of substrate-based 1,5-stereoinduction are obtained in the boron-mediated aldol reactions of P-oxygenated methyl ketones with achiral and chiral aldehydes. Remote induction from the boron enolates gives the 1,5-anti adducts, with the enolate pi-facial selectivity critically dependent upon the nature of the beta-alkoxy protecting group. This 1,5-anti aldol methodology has been strategically employed in the total synthesis of several natural products. At present, the origin of the high level of 1,5-anti induction obtained with the boron enolates is unclear, although a model based on a hydrogen bonding between the alkoxy oxygen and the formyl hydrogen has been recently proposed.3082007201

    Environmental memory boosts group formation of clueless individuals

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    The formation of groups of interacting individuals improves performance and fitness in many decentralised systems, from micro-organisms to social insects, from robotic swarms to artificial intelligence algorithms. Often, group formation and high-level coordination in these systems emerge from individuals with limited information-processing capabilities implementing low-level rules of communication to signal to each other. Here, we show that, even in a community of clueless individuals incapable of processing information and communicating, a dynamic environment can coordinate group formation by transiently storing memory of the earlier passage of individuals. Our results identify a new mechanism of indirect coordination via shared memory that is primarily promoted and reinforced by dynamic environmental factors, thus overshadowing the need for any form of explicit signalling between individuals. We expect this pathway to group formation to be relevant for understanding and controlling self-organisation and collective decision making in both living and artificial active matter in real-life environments

    The technical challenge of Functional 18F-FDG-PET Brain imaging in paediatric epilepsy

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    Epilepsy is a chronic brain disease, characterized by the appearance of crisis (whit or without convulsions), caused by abnormal electric activity on brain cells. Neuroimaging might be necessary in the work-up of epilepsy for localisation of the seizure focus for possible surgical cure. In our department, we started performing inter-ictal 18F-2-deoxyglucose (FDG)-PET/TC Brain imaging in 2009, in paediatric patients, following EANM procedure guidelines. Aim: the aim of the study was to retrospectively review all the performed inter-ictal 18F-FDG-PET/TC brain imaging, to assess the difficulties found during these procedures and the deviation according to guideline recommendations. We also intend to focus on the major importance of an optimal cooperation with other departments, such as anaesthesiology and neurophysiology. Material and Methods: between 2009 and 2012, eleven patients (pt) were referred for an 18F-FDG-PET-TC brain study, with ages between 10 months - 18 years old all with medically intractable epilepsy. The exams were performed with different conditions according to the needs of each patient, because we know that exceptional procedures call for special conditions. Results: All files were review for pt information pertinent to performance of the procedure, pt pre-arrival preparation, pt pre-injection preparation, pt monitoring for ictal crises before injection (EEG), pt sedation, variability of radiopharmaceutical administration and data acquisition parameters. 8 of the pt were performed with anaesthesia while 3 without since the pediatric patient were cooperative. All of the pt were monitored under parental surveillance, one with additional movie recording and other with EEG. Conclusion: We found that this process of retrospective review of this pool of paediatric patients with epilepsy enhanced the learning curve in this very specific procedure. We also found it critical to request the collaboration of the departments of anaesthesiology and neurophysiology

    Estimate of Effectiveness of Palivizumab in the Prevention of Respiratory Syncytial Virus-Related Hospitalizations in a Cohort of Premature Children

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    As recomendações da Secção de Neonatologia da Sociedade Portuguesa de Pediatria (SNN-SPP) prevêem a profilaxia medicamentosa da infecção por vírus sincicial respiratório (VSR) com palivizumab em idades gestacionais (IG)inferiores a 30 semanas. Alguns Hospitais de Apoio Perinatal Diferenciado seguem práticas mais restritas, limitando o seu uso à extrema prematuridade e/ou a prematuros com doença pulmonar crónica da prematuridade. Objectivos. Estimar a relação custo-eficácia da profilaxia com palivizumab segundo as recomendações da SNN-SPP, através da aplicação de um modelo teórico a uma coorte real de prematuros. Metodologia. Estudo prospectivo histórico. Coorte de crianças nascidas num Hospital de Apoio Perinatal Diferenciado entre 1/10/2002 e 30/04/2005 com IG ² 35 semanas. Considerou- se caso o internamento no mesmo hospital por bronquiolite por VSR nas épocas 2003/04 e 2004/05. Baseando-nos nas recomendações SNN-SPP e no Number Needed to Treat dos estudos IMpact e IRIS, estimámos a redução prevista nas taxas de hospitalização caso a profilaxia fosse efectuada, comparando os seus custos com a redução de custos de hospitalização. Resultados. Dos 356 recém-nascidos elegíveis, nove foram excluídos por óbito e dois por administração de palivizumab. A taxa de hospitalização por bronquiolite por VSR nas 345 crianças incluídas foi 9,3%. No subgrupo com indicação para profilaxia (26 crianças) a taxa de hospitalização foi 15,4%, com uma estimativa de custo médio de hospitalização de Û 6.542,35. Não ocorreu nenhuma morte por infecção por VSR. A redução estimável no número de hospitalizações sob profilaxia seria de 1,5 (IMpact) ou 2,4 (IRIS). O custo necessário para prevenir um internamento seria de Û 26.263,11 na melhor estimativa e Û 57.716,26 na pior estimativa. Conclusão. Com o modelo desenvolvido, não conseguimos demonstrar nesta coorte uma estimativa de relação custo-eficácia favorável à administração de Palivizumab segundo recomendações da SNN-SPP

    Natural parasitism of the Citrus Leafminer (Lepidoptera: Gracillariidae) over eight years in seven citrus regions of São Paulo, Brazil

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    The citrus leafminer (CLM) Phyllocnists citrella Stainton (Lepidoptera: Gracillariidae) was frst recorded in Brazil in 1996. In 1998, the parasitoid Ageniaspis citricola Logvinovskaya (Hymenoptera: Encyrtdae) was introduced and established in many regions of the country. In this study, 130 onehour-samplings of sweet orange leaves (Citrus sinensis [L.] Osbeck) hostng CLM pupal chambers were carried out to estmate the CLM parasitsm rate (%) by its parasitoids in 7 regions of São Paulo State between 2000 and 2008. The sample sizes varied from 10 to 275 leaves (mean = 65). The most abundant parasitoid was the encyrtd A. citricola (found in 91.8% of the samplings). The highest level of CLM parasitsm by A. citricola was recorded in the southern region (Botucatu), 70.2 ± 6.6 (mean ± SEM), and the lowest level was recorded in the northern region (Barretos), 12.8 ± 5.7%. CLM parasitsm by A. citricola and by natve parasitoids (Galeopsomyia fausta LaSalle, Cirrospilus spp. and Elasmus sp.) did not differ between seasons. The 6-fold increase in the use of insectcides in citrus groves, afer 2004 when the Huanglongbing (HLB) disease was found in São Paulo State, did not reduce the level of CLM parasitsm. The level of parasitsm was 50.8 ± 4.2% before the advent of HLB (2000–2004) and 56.0 ± 4.4% thereafer (2005–2008), indicatng adaptaton of A. citricola in a disturbed agroecosystem.A minadora das folhas dos citros (MFC), Phyllocnistis citrella Stainton (Lepidoptera: Gracillariidae), foi encontrada pela primeira vez no Brasil em 1996. Em 1998, o parasitoide Ageniaspis citricola Logvinovskaya (Hymenoptera: Encyrtidae) foi introduzido e se estabeleceu em várias regiões do país. Nesse estudo, foram feitas130 amostragens, de uma hora, de folhas de laranjeiras doces [Citrus sinensis (L.) Osbeck] com câmaras pupais da MFC, para se estimar o parasitismo da MFC em 7 regiões do estado de São Paulo, entre 2000 e 2008. O tamanho das amostras variou de 10 a 275 folhas (média = 65). O parasitoide mais abundante foi o encirtídeo A. citricola (encontrado em 91.8% das amostragens). O maior parasitismo da MFC por A. citricola foi observado na região sul do estado (Botucatu), 70,2 ± 6,6 (média ± EPM), e o menor parasitismo na região norte (Barretos), 12,8 ± 5,7%. O parasitismo da MFC por A. citricola e seus parasitoides nativos (Galeopsomyia fausta LaSalle, Cirrospilus spp. and Elasmus sp.) não diferiram entre as estações do ano. O aumento de seis vezes no uso de inseticidas nos pomares de citros, após 2004, quando o Huanglongbing (HLB) foi encontrado no estado de São Paulo, não reduziu o nível de parasitismo da MFC. O nível médio de parasitismo foi de 50,8 ± 4,2%, antes do HLB (2000-2004), e 56,0 ± 4,4%, após o HLB (2005-2008), indicando a adaptação de A. citricola a um agroecossistema perturbado.info:eu-repo/semantics/publishedVersio

    Metabolic modelling of polyhydroxyalkanoate copolymers production by mixed microbial cultures

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    Background: This paper presents a metabolic model describing the production of polyhydroxyalkanoate (PHA) copolymers in mixed microbial cultures, using mixtures of acetic and propionic acid as carbon source material. Material and energetic balances were established on the basis of previously elucidated metabolic pathways. Equations were derived for the theoretical yields for cell growth and PHA production on mixtures of acetic and propionic acid as functions of the oxidative phosphorylation efficiency, P/O ratio. The oxidative phosphorylation efficiency was estimated from rate measurements, which in turn allowed the estimation of the theoretical yield coefficients. Results: The model was validated with experimental data collected in a sequencing batch reactor (SBR) operated under varying feeding conditions: feeding of acetic and propionic acid separately (control experiments), and the feeding of acetic and propionic acid simultaneously. Two different feast and famine culture enrichment strategies were studied: (i) either with acetate or (ii) with propionate as carbon source material. Metabolic flux analysis (MFA) was performed for the different feeding conditions and culture enrichment strategies. Flux balance analysis (FBA) was used to calculate optimal feeding scenarios for high quality PHA polymers production, where it was found that a suitable polymer would be obtained when acetate is fed in excess and the feeding rate of propionate is limited to ∼0.17 C-mol/ (C-mol.h). The results were compared with published pure culture metabolic studies. Conclusion: Acetate was more conducive toward the enrichment of a microbial culture with higher PHA storage fluxes and yields as compared to propionate. The P/O ratio was not only influenced by the selected microbial culture, but also by the carbon substrate fed to each culture, where higher P/O ratio values were consistently observed for acetate than propionate. MFA studies suggest that when mixtures of acetate and propionate are fed to the cultures, the catabolic activity is primarily guaranteed through acetate uptake, and the characteristic P/O ratio of acetate prevails over that of propionate. This study suggests that the PHA production process by mixed microbial cultures has the potential to be comparable or even more favourable than pure cultures.publishersversionpublishe

    Obesity and Diabetes Are Associated with Disability in Women with Hand Osteoarthritis. Results from the EpiReumaPt Nationwide Study

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    Background: Hand osteoarthritis (HOA) is a highly prevalent rheumatic disease that predominates in females and causes pain and loss of functional capacity. Obesity and metabolic syndrome have been previously suggested to associate with the severity of HOA, but clarity on these associations is yet to be achieved. Objective: Test the association between obesity and other components of the metabolic syndrome and disability in women with hand osteoarthritis (HOA). Design: Individuals from EpiReumaPt epidemiological community-based study (2011-2013) are representative of the Portuguese population. Women with diagnosis of primary HOA were included. Primary outcome: hand functional status, assessed by Cochin questionnaire. Secondary outcomes: hand pain, assessed by visual analogue scale and tender hand joint count (THJ). Explanatory variables: obesity, diabetes mellitus, arterial hypertension and hypercholesterolemia. Possible associations between obesity and the other components of metabolic syndrome with Cochin score, hand pain and THJ were tested in a multivariable linear regression model. Potential confounders considered: age, education level and countrywide distribution. Results: 473 women with primary HOA were included. Forty percent were overweight and 29% obese. Ninety-three (19.8%) participants had diabetes, 261 (55.8%) reported hypertension and 261 (55.9%) hypercholesterolemia. Mean Cochin score was 15.5±14.8, mean pain VAS was 4.7±2.6 and mean THJ 1.4±3. In the multivariable analysis, obesity (β 4.6 CI 0.7;8.5) and diabetes (β 4.0 CI 0.4;7.6) were found to significantly associate with HOA functional disability. In addition, diabetes, but not obesity, associated with hand pain. There was no association between obesity or diabetes with THJ. Conclusion: In a Portuguese female population with primary HOA, obesity and diabetes mellitus independently associated with a worse hand functional status. These data add to evidence suggesting a role of metabolic factors in the severity of HOA.info:eu-repo/semantics/publishedVersio
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