Automatização em nutrição parentérica: controlo de qualidade antes e após a sua implementação / Automation in parenteral nutrition: quality control of the process before and after it`s implementation

A nutrição parentérica (NP) desempenha um papel vital em doentes críticos, sendo muitas vezes necessária a sua preparação personalizada, ajustada às necessidades de doentes com carências específicas. A manipulação de NP poderá ser realizada de forma manual ou automatizada, requerendo sempre condições asséticas e pessoal treinado. A implementação de um sistema automatizado requer uma análise cuidada da sua necessidade/justificação, de forma a que, baseado em fundamentação adequada, se estruture um plano exequível. A monitorização do desempenho do sistema automatizado é um processo fundamental de validação farmacêutica. Nos Serviços Farmacêuticos (SF) do Centro Hospitalar e Universitário de São João (CHUSJ), elaborou-se um estudo de controlo de qualidade gravimétrico antes e após implementação do sistema automatizado, no sentido de monitorizar a precisão dos resultados obtidos para este ensaio de verificação. Como resultados estatísticos, o método de enchimento automatizado relacionou-se com a menor média para o desvio ao peso teórico, assim como menor desvio padrão, corroborando uma menor percentagem de erro e também uma menor dispersão dos resultados. Da análise dos resultados obtidos concluiu-se que a implementação da automatização se traduziu em melhorias a nível de precisão de resultados para o controlo gravimétrico das bolsas nutritivas, aumentando a segurança das misturas produzidas e, consequentemente, a qualidade dos cuidados prestados ao doente. É de elevada importância que se implementem procedimentos de validação do desempenho do sistema automatizado, como foi o caso, sendo que deverão ser complementados com outro tipo de avaliações, preferencialmente realizadas por entidades externas à instituição em causa. (AU)

Parenteral nutrition (PN) plays a vital role in critically ill patients and custom preparation is often necessary, adjusted to the needs of patients with specific needs. Compounding PN handling can be performed manually or automated, always requiring aseptic conditions and trained personnel. The implementation of an automated system requires a careful analysis of its need/ justification, so that, based on adequate rationale, a feasible execution plan may be structured. Monitoring the performance of the automated system is a key process which requires of pharmaceutical validation. In the Pharmaceutical Service of the Centro Hospitalar e Universitário de São João (CHUSJ), a study of gravimetric quality control was carried out before and after the implementation of the automated system, in order to monitor the accuracy of the results obtained for this verification test. As statistical results, the automated filling method was related to the lower average for the deviation to the theoretical weight, as well as lower standard deviation, corroborating a lower percentage of error but also a smaller dispersion of the results with this method. From the analysis of the results obtained, it was concluded that the implementation of automation resulted in improvements in the accuracy of results for the gravimetric control of nutritional bags, increasing the safety of the mixtures produced and, consequently, the quality of care provided to the patient. It is of highly importance that procedures for validating the performance of the automated system are implemented, as was the case, and these should be complemented by other types of evaluations, preferably performed by external entities to the institution in question. (AU)

Timing of CNS cell generation: a programmed sequence of neuron and glial cell production from isolated murine cortical stem cells.

Multipotent stem cells that generate both neurons and glia are widespread components of the early neuroepithelium. During CNS development, neurogenesis largely precedes gliogenesis: how is this timing achieved? Using clonal cell culture combined with long-term time-lapse video microscopy, we show that isolated stem cells from the embryonic mouse cerebral cortex exhibit a distinct order of cell-type production: neuroblasts first and glioblasts later. This is accompanied by changes in their capacity to make neurons versus glia and in their response to the mitogen EGF. Hence, multipotent stem cells alter their properties over time and undergo distinct phases of development that play a key role in scheduling production of diverse CNS cells.

Stem cells in the embryonic cerebral cortex: their role in histogenesis and patterning.

The cytoarchitectural simplicity of the cerebral cortex makes it an attractive system to study central nervous system (CNS) histogenesis--the process whereby diverse cells are generated in the right numbers at the appropriate place and time. Recently, multipotent stem cells have been implicated in this process, as progenitor cells for diverse types of cortical neurons and glia. Continuous analysis of stem cell clone development reveals stereotyped division patterns within their lineage trees, highly reminiscent of neural lineage trees in arthropods and Caenorhabditis elegans. Given that these division patterns play a critical part in generating diverse neural types in invertebrates, we speculate that they play a similar role in the cortex. Because stereotyped lineage trees can be observed from cells growing at clonal density, cell-intrinsic factors are likely to have a key role in stem cell behavior. Cortical stem cells also respond to environmental signals to alter the types of cells they generate, providing the means for feedback regulation on the germinal zone. Evidence is accumulating that cortical stem cells, influenced by intrinsic programs and environmental signals, actually change with development-for example, by reducing the number and types of neurons they produce. Age-related changes in the stem cell population may have a critical role in orchestrating development; whether these cells truly self-renew is a point of discussion. In summary, we propose that cortical stem cells are the focus of regulatory mechanisms central to the development of the cortical cytoarchitecture.

Ca2+ stores in the chick embryo retina cells.

The Ca2+ stores of digitonin permeabilized chick embryo retina cells in culture were characterized, by using the fluorescence of Fluo-3 potassium salt to follow continuously the free [Ca2+] in the medium. After ATP dependent Ca2+ accumulation, the Ca2+ release was induced by several agents; 10 microM cyclic-ADP-ribose (cADPR), 40 microM Ins (1,4,5)P3 10 microM thapsigargin (Th), 25 microM ionomycin (Ion), 15 microM CCCP together with 4.5 micrograms/ml oligomycin (CCCP/Olig), 50 microM arachidonic acid (AA). Neither Ins(1,4,5)P3 nor cADPR were able to mobilize Ca2+ from internal stores in these cells, but Th and AA were effective in releasing Ca2+. Four major Ca2+ stores in chick embryo retina cells were distinguished: i) the thapsigargin sensitive Ca2+ store, most likely the ER; ii) the Ca2+ store sensitive to oligomycin and CCCP, most likely the mitochondrial Ca2+ store, iii) an AA sensitive Ca2+ store, which is distinct from the previous two; and, iv) the Ca2+ store only sensitive to ionomycin. The capacities of these different Ca2+ stores of the chick embryo retina cells, relative to the total intracellular stores, are: 63.3%, 14.1%, 8.2%, for the ER, the mitochondrial and for the AA sensitive Ca2+ stores, respectively.

Ontogeny of the L-type voltage sensitive calcium channels in chick embryo retinospheroids.

The L-type voltage sensitive calcium channels (VSCC) of chick embryo retinospheroids were characterized during the development in vitro. Functionally, the activity of VSCC was characterized by continuously monitoring the changes in the intracellular free Ca2+ concentration (delta[Ca2+]i) with indo-1, in response to 30 mM KCl. The contribution of the L-type VSCC was evaluated using the L-type VSCC antagonist, nitrendipine. We also characterized the binding of [3H]nitrendipine to retinospheroid membranes during development, and determined the Kd and Bmax values. We observed that the changes in [Ca2+]i in response to 30 mM KCl increased from 159.46 +/- 6.62 nM at 0 days in vitro (DIV) retinospheroids to 704.4 +/- 59.9 nM at 14 DIV retinospheroids. Nitrendipine (2 microM) blocked the delta[Ca2+]i response by approximately 67% in all ages tested. No significant difference in the Kd values for the nitrendipine binding was observed during in vitro development of the retinospheroids. However, the Bmax increased from 27.99 +/- 1.95 fmol/mg protein in 0 DIV retinospheroids to 131.09 +/- 14.24 fmol/mg protein in 14 DIV retinospheroids, supporting the delta[Ca2+]i results. The results presented suggest that the increase in [Ca2+]i during development was due to an increase in the number of L-type channels. Therefore, the expression of L-type VSCC is developmentally regulated during retinogenesis in vitro and accompanies neuronal maturation, probably regulating the Ca2+ input crucial to the onset of important intracellular Ca2+-dependent functions.