Regulated secretory proteins are stored within specialized vesicles known as secretory granules. It is not known how proteins are sorted into these organelles. Regulated proteins may possess targeting signals which interact with specific sorting receptors in the lumen of the trans‐Golgi network (TGN) prior to their aggregation to form the characteristic dense‐core of the granule. Alternatively, sorting may occur as the result of specific aggregation of regulated proteins in the TGN. Aggregates may be directed to secretory granules by interaction of (...) a targeting signal on the surface with a sorting receptor. Novel targeting signals which confer on regulated proteins a tendency to aggregate under certain conditions, and in so doing cause them to be incorporated into secretory granules, have been implicated. Specific targeting signals may also play a role in directing membrane proteins to secretory granules. (shrink)

In this paper I propose a reading of Plotinus Enneads VI.1-3 [41-43] On the genera of being which regards this treatise as a coherent whole in which Aristotle's "Categories" is explored in a way that turns it into a decisive contribution to Plotinus' Platonic ontology. In addition, I claim that Porphyry's Isagoge and commentaries on the "Categories" start by adopting Plotinus' point of view, including his notion of genus, and proceed by explaining its consequences for a more detailed reading of (...) the "Categories." After Plotinus' integration of the "Categories" into the Platonic frame of thought Porphyry saw the possibilities of exploiting the Peripatetic tradition both as a means to support the Platonic interpretation of the "Categories" and as a source for solutions to traditional questions. His allegiance to a division of being into ten, and his emphasis on semantics rather than ontology can be explained from this orientation. In the light of our investigation the alleged disagreement between Plotinus and Porphyry on the "Categories" changes its appearance completely. There are differences, but these can be best explained as confirmation and extension of Plotinus' perspective on the "Categories" and its role in Platonism. (shrink)

Deterministic models in population dynamics often are really approximations to stochastic models, justified by an appeal to the law of large numbers. It is proposed to call such models pseudodeterministic. Four questions are discussed in this article: (1) What errors may be made by equating deterministically predicted values to expectations? (2) When, and in what sense, may numbers be assumed to be large? (3) How large are the variances, coefficients of variations, etc., as assigned to the variables in the stochastic (...) versions of the models? (4) What role may pseudodeterministic models play in empirical research, where problems of statistical reliability arise?As an example, a modified Nicholson-Bailey model of the interaction between insect parasitoids and their hosts is discussed; the modification consists of assigning a random (density-independent) mortality to the parasitoid population. A stochastic version of this model is discussed. The expectation of the final host density is compared with the value computed from the deterministic model. The latter value is systematically lower than the former. The magnitude of the difference depends on parameter values. The variability to be expected with the stochastic model is characterized by the coefficient of variation of the final host density; its dependence on parameter values and initial conditions is discussed. It is concluded that it is worthwhile in practical applications to estimate parasitoid mortality, and that the coefficient of variation in real situations may be far from negligible. (shrink)

To describe the content of practice guidelines on euthanasia and assisted suicide (EAS) and to compare differences between settings and guidelines developed before or after enactment of the euthanasia law in 2002 by means of a content analysis. Most guidelines stated that the attending physician is responsible for the decision to grant or refuse an EAS request. Due care criteria were described in the majority of guidelines, but aspects relevant for assessing these criteria were not always described. Half of the (...) guidelines described the role of the nurse in the performance of euthanasia. Compared with hospital guidelines, nursing home guidelines were more often stricter than the law in excluding patients with dementia (30% vs 4%) and incompetent patients (25% vs 4%). As from 2002, the guidelines were less strict in categorically excluding patients groups (32% vs 64%) and in particular incompetent patients (10% vs 29%). Healthcare institutions should accurately state the boundaries of the law, also when they prefer to set stricter boundaries for their own institution. Only then can guidelines provide adequate support for physicians and nurses in the difficult EAS decision-making process. (shrink)