Selection bias: neighbourhood controls and controls selected from those presenting to a Health Unit in a case control study of efficacy of BCG revaccination.

BACKGROUND: In most case control studies the hardest decision is the choice of the control group, as in the ideal control group the proportion exposed is the same as in the population that produced the cases. METHODS: A comparison of two control groups in a case control study of the efficacy of BCG revaccination. One group was selected from subjects presenting to the heath unit the case attended for routine prevention and care; the second group was selected from the neighbourhood of cases. All Health Units from which controls were selected offered BCG revaccination. Efficacy estimated in a randomized control trial of BCG revaccination was used to establish that the neighbourhood control group was the one that gave unbiased results. RESULTS: The proportion of controls with scars indicating BCG revaccination was higher among the control group selected from Health Unit attenders than among neighbourhood controls. This excess was not removed after control for social variables and history of exposure to tuberculosis, and appears to have resulted from the fact that people attending the Health Unit were more likely to have been revaccinated than neighbourhood controls, although we can not exclude an effect of other unmeasured variables. CONCLUSION: In this study, controls selected from people presenting to a Health Unit overrepresented exposure to BCG revaccination. Had the results from the HU attenders control group been accepted this would have resulted in overestimation of vaccine efficacy. When the exposure of interest is offered in a health facility, selection of controls from attenders at the facility may result in over representation of exposure in controls and selection bias

Combined use of chitosan and olfactory mucosa mesenchymal stem/stromal cells to promote peripheral nerve regeneration in vivo

Peripheral nerve injury remains a clinical challenge with severe physiological and functional consequences. Despite the existence of multiple possible therapeutic approaches, until now, there is no consensus regarding the advantages of each option or the best methodology in promoting nerve regeneration. Regenerative medicine is a promise to overcome this medical limitation, and in this work, chitosan nerve guide conduits and olfactory mucosa mesenchymal stem/stromal cells were applied in different therapeutic combinations to promote regeneration in sciatic nerves after neurotmesis injury. Over 20 weeks, the intervened animals were subjected to a regular functional assessment (determination of motor performance, nociception, and sciatic indexes), and after this period, they were evaluated kinematically and the sciatic nerves and cranial tibial muscles were evaluated stereologically and histomorphometrically, respectively. The results obtained allowed confirming the beneficial effects of using these therapeutic approaches. The use of chitosan NGCs and cells resulted in better motor performance, better sciatic indexes, and lower gait dysfunction after 20 weeks. The use of only NGGs demonstrated better nociceptive recoveries. The stereological evaluation of the sciatic nerve revealed identical values in the different parameters for all therapeutic groups. In the muscle histomorphometric evaluation, the groups treated with NGCs and cells showed results close to those of the group that received traditional sutures, the one with the best final values. The therapeutic combinations studied show promising outcomes and should be the target of new future works to overcome some irregularities found in the results and establish the combination of nerve guidance conduits and olfactory mucosa mesenchymal stem/stromal cells as viable options in the treatment of peripheral nerves after injury.info:eu-repo/semantics/publishedVersio

Rat olfactory mucosa mesenchymal stem/stromal cells (om-mscs): a characterization study

Stem/stromal cell-based therapies are a branch of regenerative medicine and stand as an attractive option to promote the repair of damaged or dysfunctional tissues and organs. Olfactory mucosa mesenchymal stem/stromal cells have been regarded as a promising tool in regenerative therapies because of their several favorable properties such as multipotency, high proliferation rate, helpful location, and few associated ethical issues. These cells are easily accessible in the nasal cavity of most mammals, including the rat, can be easily applied in autologous treatments, and do not cope with most of the obstacles associated with the use of other stem cells. Despite this, its application in preclinical trials and in both human and animal patients is still limited because of the small number of studies performed so far and to the nonexistence of a standard and unambiguous protocol for collection, isolation, and therapeutic application. In the present work a validation of a protocol for isolation, culture, expansion, freezing, and thawing of olfactory mucosa mesenchymal stem/stromal cells was performed, applied to the rat model, as well as a biological characterization of these cells. To investigate the therapeutic potential of OM-MSCs and their eventual safe application in preclinical trials, the main characteristics of OMSC stemness were addressed.info:eu-repo/semantics/publishedVersio

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

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

Zoneamento de risco climático para a cultura da mangueira no Estado da Bahia.

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