Neural networks on chemically patterned "cultured probe" electrode arrays: network growth and activity patterns

A 'cultured probe' is a hybrid type of neural information transducer or prosthesis, for stimulation and/or recording of neural activity in the brain or the spinal cord (ventral motor region or dorsal sensory region). It consists of a micro electrode array (MEA) on a planar substrate, each electrode being covered and surrounded by a locally confined network of cultured neurons, obtained by chemical patterning of the substrate. The purpose of the cultured cells is that they act as intermediates for collateral sprouts from the in vivo system, thus allowing for an effective and selective neuron electrode interface. As the local neural network will become spontaneously active and has the capability of information processing, one may envisage future applications of these intermediary networks as 'front-end' signal processors. Two aspects of the development of this kind of cultured probe device are described. First, it is shown how substrates can be chemically modified to confine developing networks, cultured from dissociated rat cortex cells, to the surrounding of an electrode site. Secondly, the paper presents results on neuronal activity in such confined, circular networks and synchronized activity between two such interconnected networks

Insulin-like growth factor-II in the cycle of life

The insulin-like growth factors (IGF-I and IGF-II) play important roles in growth and development. They are structurally homologous to proinsulin and can interact with the type I and type II IGF receptors and, to a lesser extent, the insulin receptor. IGF have potent hypoglycemic activity, which is modulated by the presence of specific IGF-binding proteins, six of which (IGFBP-1 to IGFBP-6) have been cloned to date. Postnatally, IGF-stimulated growth is merely regulated by pituitary-derived growth hormone (GH). However, prenatal growth regulation by IGF is GH-independent. IGF and IGFBP are produced by many tissues and circulate in plasma, suggesting that they act both by endocrine and autocrine/paracrine mechanisms. In spite of the vast literature about IGF, their physiological implications in prenatal and postnatal growth regulation are insufficiently known. This is especially true for IGF-II. Therefore, this article will dance round a few selected aspects relevant to the biological effects of IGF-II in vivo.Biomedical Reviews 1996; 5: 65-71

Misconceptions about fructose-containing sugars and their role in the obesity epidemic.

A causal role of fructose intake in the aetiology of the global obesity epidemic has been proposed in recent years. This proposition, however, rests on controversial interpretations of two distinct lines of research. On one hand, in mechanistic intervention studies, detrimental metabolic effects have been observed after excessive isolated fructose intakes in animals and human subjects. On the other hand, food disappearance data indicate that fructose consumption from added sugars has increased over the past decades and paralleled the increase in obesity. Both lines of research are presently insufficient to demonstrate a causal role of fructose in metabolic diseases, however. Most mechanistic intervention studies were performed on subjects fed large amounts of pure fructose, while fructose is ordinarily ingested together with glucose. The use of food disappearance data does not accurately reflect food consumption, and hence cannot be used as evidence of a causal link between fructose intake and obesity. Based on a thorough review of the literature, we demonstrate that fructose, as commonly consumed in mixed carbohydrate sources, does not exert specific metabolic effects that can account for an increase in body weight. Consequently, public health recommendations and policies aiming at reducing fructose consumption only, without additional diet and lifestyle targets, would be disputable and impractical. Although the available evidence indicates that the consumption of sugar-sweetened beverages is associated with body-weight gain, and it may be that fructose is among the main constituents of these beverages, energy overconsumption is much more important to consider in terms of the obesity epidemic

Spatiotemporal regulation of Rho GTPase signaling during endothelial barrier remodeling

The vasculature is characterized by a thin cell layer that comprises the inner wall of all blood vessels, the continuous endothelium. Endothelial cells can also be found in the eye's cornea. And even though cornea and vascular endothelial (VE) cells differ from each other in structure, they both function as barriers and express similar junctional proteins such as the adherens junction VE-cadherin and tight-junction member claudin-5. How these barriers are controlled to maintain the barrier and thereby its integrity is of major interest in the development of potential therapeutic targets. An important target of endothelial barrier remodeling is the actin cytoskeleton, which is centrally coordinated by Rho GTPases that are in turn regulated by Rho-regulatory proteins. In this review, we give a brief overview of how Rho-regulatory proteins themselves are spatiotemporally regulated during the process of endothelial barrier remodeling. Additionally, we propose a roadmap for the comprehensive dissection of the Rho GTPase signaling network in its entirety

In vreemde grond geworteld:Prerafaëlitisme in de Nederlandse literatuur en beeldende kunst (1855-1910)

In 1848 richtte een groep jonge Engelse schilders en schrijvers de ‘Pre-Raphaelite Brotherhood’ op. Hun doel was zich gezamenlijk in te zetten voor de vernieuwing van de kunsten. Aan het einde van de negentiende eeuw groeide het prerafaëlitisme uit tot een brede culturele beweging. Met de term ‘prerafaëlitisme’ werd niet langer alleen het werk van de leden van de broederschap aangeduid, maar ook andere Engelse literatuur, beeldende en toegepaste kunst uit de periode 1848-1900. Dit amalgaam van Engelse literatuur en kunst heeft in Nederland een grote impact gehad. In het eerste deel van het boek worden vier opeenvolgende fasen in de Nederlandse receptie van het prerafaëlitisme beschreven: een opstartfase in de periode 1855-1880, een fase van intensieve receptie in het domein van de literatuur in de jaren tachtig, een periode van oriëntatie op prerafaëlitische decoratieve kunst door gemeenschapskunstenaars in de jaren negentig, en een periode, na 1900, waarin de receptie afnam en langzaam minder positief werd. Op het receptie-historisch overzicht volgen vijf hoofdstukken waarin ingezoomd wordt op vijf belangrijke recipiënten: de schrijvers Frederik van Eeden, Edward B. Koster en P.C. Boutens, en de kunstenaars Antoon Derkinderen en Jan Toorop. Hun omgang met het prerafaëlitisme in de vorm van kritische receptie, creatieve receptie en vertaalarbeid komt hierin extensief aan bod. Samen laten het chronologisch overzicht en het vijftal dieptepeilingen zien hoe het prerafaëlitisme tijdens het fin de siècle in Nederlandse grond geworteld raakte en wat de Engelse cultuur voor belang heeft gehad voor de vorming van de Nederlandse

Chronic obstructive pulmonary disease : new insights in morning symptons and physical activity

Chronic obstructive pulmonary disease (COPD) is a chronic lung disease, characterised by inflammation and destruction of the airways. There are no curative options yet. However, COPD is a treatable disease, whereby reduction of symptoms is a major treatment goal. In this thesis, we focussed on morning symptoms. The relation between morning symptoms and physical activity was studied in search of novel treatment options. We concluded in a systematic review that there was a negative association between morning symptoms and self-reported physical activity. We confirmed this association in the MOrning symptoms in-Depth observationAl Study (MODAS), an observational cross-sectional study, in which we objectively measured physical activity. We also found that patients with high morning symptom scores took fewer steps in morning and afternoon than those with low morning symptom scores, but not during evening and night. These factors can be used as targets in future interventional studies. A subsequent real life study showed that participating physicians recorded more symptoms and lifestyle advises when a designated approach was used. To pay more attention to morning symptoms and physical activity in clinical practice, we encourage the use of a systematic approach that includes these items. Unrestricted research grant from NovartisLUMC / Geneeskund