Investigations into the mechanism of action of nitrobenzene as a mild dehydrogenating agent under acid-catalysed conditions

Protonated nitrobenzene can be used to dehydrogenate a range of hydrocarbons, which already possess at least one double bond. Kinetic and spectroscopic results, together with known electrode potentials, yield approximate limits within which protonated nitrobenzenes can be expected to effect dehydrogenation of hydroaromatic compounds. A high yielding synthesis of benzo[ j ]fluoranthene is described

Estudo químico de óleos essenciais, oleaginosas e látices da Amazônia. I. Composição e oxidação do óleo de uma espécie de Copaifera (Nota prévia).

Preliminar note on a study of the resta oil (from the trunk) and the seed oil from a species of Copaifera was done, using the analytical methods known as GC/MS and HPLC and the volumetric method. This work was developed at the Divisão de Química of the INPA in collaboration with the Departamento de Química of the UPCe with the purpose to identify the chemical components and to establish the kinetic control of auto oxidation with and without the addition of antioxidants and synergistic agents

Effects of collagen membranes enriched with in vitro-differentiated N1E-115 cells on rat sciatic nerve regeneration after end-to-end repair

Peripheral nerves possess the capacity of self-regeneration after traumatic injury but the extent of regeneration is often poor and may benefit from exogenous factors that enhance growth. The use of cellular systems is a rational approach for delivering neurotrophic factors at the nerve lesion site, and in the present study we investigated the effects of enwrapping the site of end-to-end rat sciatic nerve repair with an equine type III collagen membrane enriched or not with N1E-115 pre-differentiated neural cells. After neurotmesis, the sciatic nerve was repaired by end-to-end suture (End-to-End group), end-to-end suture enwrapped with an equine collagen type III membrane (End-to-EndMemb group); and end-to-end suture enwrapped with an equine collagen type III membrane previously covered with neural cells pre-differentiated in vitro from N1E-115 cells (End-to-EndMembCell group). Along the postoperative, motor and sensory functional recovery was evaluated using extensor postural thrust (EPT), withdrawal reflex latency (WRL) and ankle kinematics. After 20 weeks animals were sacrificed and the repaired sciatic nerves were processed for histological and stereological analysis. Results showed that enwrapment of the rapair site with a collagen membrane, with or without neural cell enrichment, did not lead to any significant improvement in most of functional and stereological predictors of nerve regeneration that we have assessed, with the exception of EPT which recovered significantly better after neural cell enriched membrane employment. It can thus be concluded that this particular type of nerve tissue engineering approach has very limited effects on nerve regeneration after sciatic end-to-end nerve reconstruction in the rat

Critérios metodológicos e potencial climático do Estado de Alagoas para culturas agrícolas nos cenários pluviométricos seco, regular e chuvoso.

Este trabalho apresenta a aptidão climática do Estado de Alagoas para oito culturas agrícolas: algodão herbáceo, cana-de-açúcar, feijão phaseolus, feijão vigna, mamona, mandioca, milho e sorgo. O estudo foi desenvolvido pela Embrapa Solos UEP Recife, em parceria com o Governo do Estado de Alagoas / Secretaria de Estado da Agricultura e Desenvolvimento Agrário, com o objetivo de gerar informações para subsidiar o planejamento e o aperfeiçoamento do uso das terras do estado. No que se refere à metodologia, foram utilizados procedimentos diferentes dos tradicionalmente adotados nos zoneamentos climáticos, os quais se baseiam nas médias históricas dos totais mensais de chuva. Nesta nova abordagem, três cenários pluviométricos foram considerados: anos secos, anos regulares e anos chuvosos, com base nas séries históricas de dados de chuva, as quais representam a variabilidade natural do regime pluviométrico. A ideia é que um dos cenários pluviométricos disponibilizados seja adotado pelo usuário, em função dos prognósticos de previsão pluviométrica publicados antecipadamente pelos núcleos de meteorologia, obtidos por meio de análises dos modelos numéricos regionais e globais atualmente em uso. Esta nova abordagem climatológica é especialmente importante nos ambientes semiáridos do Nordeste do Brasil, onde são grandes as variações anuais nas precipitações pluviométricas. Observou-se que nos anos considerados secos a deficiência hídrica restringe o cultivo de praticamente todas as culturas no semiárido de Alagoas. Nesse cenário de menor precipitação pluvial, o sorgo, o algodão, a mamona e o feijão caupi sofrem menor restrição para seu cultivo em função da maior tolerância às condições de deficiência hídrica. Em anos com chuvas regulares, cerca de 40% da área do estado não apresenta restrições climáticas para as culturas avaliadas, excetuando-se o milho e o feijão phaseolus. Os anos chuvosos apresentam as melhores condições climáticas para os cultivos, no entanto, partes da região da Zona da Mata e do Litoral do estado podem apresentar moderado excesso hídrico, podendo prejudicar a colheita e secagem de grãos, principalmente nas áreas limítrofes com o Estado de Pernambuco.bitstream/item/184436/1/BPD-251-Criterios-metodologicos-AL-Mapas-Otimizado.pd

Use of chitosan scaffolds for repairing rat sciatic nerve defects

Neurotmesis must be surgically treated by direct end-to-end suture of the two nerve stumps or by a nerve graft harvested from elsewhere in the body in case of tissue loss. To avoid secondary damage due to harvesting of the nerve graft, a tube-guide can be used to bridge the nerve gap. Previously, our group developed and tested hybrid chitosan membranes for peripheral nerve tubulization and showed that freeze-dried chitosan type III membranes were particularly effective for improving peripheral nerve functional recovery after axonotmesis. Chitosan type III membranes have about 110 µm pores and about 90% of porosity, due to the employment of freeze-drying technique. The present study aimed to verify if chitosan type III membranes can be successfully used also for improving peripheral nerve functional recovery after neurotmesis of the rat sciatic nerve. Sasco Sprague-Dawley adult rats were divided into 6 groups: Group 1: end-to-end neurorrhaphy enwrapped by chitosan membrane type III (End-to-EndChitIII); Group 2: 10mm-nerve gap bridged by an autologous nerve graft enwrapped by chitosan membrane type III (Graft180ºChitIII); Group 3: 10mm-nerve gap bridged by chitosan type III tube-guides (GapChitIII); These 3 experimental groups were compared with 3 control groups, respectively: Group 4: 10mm-nerve gap bridged by an autologous nerve graft (Graft180º); Group 5: 10mm-nerve gap bridged by PLGA 90:10 tube-guides (PLGA); Group 6: end-to-end neurorrhaphy alone (End-to-End). Motor and sensory functional recovery were evaluated throughout a healing period of 20 weeks using extensor postural thrust (EPT), withdrawal reflex latency (WRL) and ankle kinematics. Regenerated nerves withdrawn at the end of the experiment were analysed histologically. Results showed that nerve regeneration was successful in all experimental and control groups and that chitosan type III tubulization induced a significantly better nerve regeneration and functional recovery in comparison to PLGA tubulization control. Further investigation is needed to explore the mechanisms at the basis of the positive effects of chitosan type III on axonal regeneration

The S phase checkpoint promotes the Smc5/6 complex dependent SUMOylation of Pol2, the catalytic subunit of DNA polymerase ε

Replication fork stalling and accumulation of single-stranded DNA trigger the S phase checkpoint, a signalling cascade that, in budding yeast, leads to the activation of the Rad53 kinase. Rad53 is essential in maintaining cell viability, but its targets of regulation are still partially unknown. Here we show that Rad53 drives the hyper-SUMOylation of Pol2, the catalytic subunit of DNA polymerase ε, principally following replication forks stalling induced by nucleotide depletion. Pol2 is the main target of SUMOylation within the replisome and its modification requires the SUMO-ligase Mms21, a subunit of the Smc5/6 complex. Moreover, the Smc5/6 complex co-purifies with Pol ε, independently of other replisome components. Finally, we map Pol2 SUMOylation to a single site within the N-terminal catalytic domain and identify a SUMO-interacting motif at the C-terminus of Pol2. These data suggest that the S phase checkpoint regulate Pol ε during replication stress through Pol2 SUMOylation and SUMO-binding abilit