Technieken voor het uitsluiten van urineweginfecties : labquiz

Van alle klachten en aandoeningen waarmee vrouwen een arts consulteren, komt een urineweginfectie (UWI) het meest voor. De gouden standaard voor het aantonen van een UWI is een urinek week. Omdat de uitslag van een urinekweek echter vaak pas na 3 dagen bekend is, zijn er andere technieken waarmee een mogelijke UWI eerder kan worden uitgesloten. Op basis van welke test mag de arts een urineweginfectie uitsluiten?Urinary tract infections (UTIs) are the most common infections in both hospitalised patients and the general community. The gold standard for diagnosing an UTI is a positive bacterial culture. Unfortunately, bacterial culture is a time-consuming procedure, leading to a delay in proper treatment. This problem is often circumvented by diagnosing on clinical manifestation alone; however, diagnosis on symptoms alone will lead to an overestimation of the incidence of UTI. Employing a screening method to identify samples that do not have to be cultured has a positive effect on time-to-diagnosis, which is why screening methods to rule out UTI have been developed. The current screening methods and their pitfalls are described here, illustrated by two patient cases. A relatively new technique is also introduced: urine screening by flow cytometry. This overview updates the reader on how to exclude a urinary tract infection using screening methods

Differential regulation of the Wilms' tumor gene, WT1, during differentiation of embryonal carcinoma and embryonic stem cells.

The expression pattern of the Wilms' tumor suppressor gene, WT1, during embryonal development suggests a role for the WT1 proteins in the differentiation of specific tissues. This notion is supported by the observation that WT1 knock-out mice fall to develop kidneys and gonads. We describe here the changes in the expression and DNA binding activity of the WT1 gene product in P19 embryonal carcinoma cells and embryonic stem cells triggered to differentiate by either retinoic acid (RA) or DMSO. In exponentially growing P19 embryonal carcinoma (EC) cells, WT1 mRNA and proteins were undetectable. During RA-induced but not DMSO-induced differentiation of P19 EC cells, WT1 expression and DNA binding are strongly activated. Treatment of embryonic stem cells with RA resulted in a similar activation of WT1. Immunohistochemical analysis showed that WT1 is expressed in endodermal, glial, and epithelial cell types. In addition, DNA binding by EGR-1, a transcription factor structurally related to WT1, increased during differentiation of P19 EC and embryonic stem cells. To investigate the possible functional consequences of DNA binding by WT1, we examined the expression levels of two putative transcriptional targets of WT1, the insulin-like growth factor 1 receptor and epidermal growth factor receptor. We found that after an initial induction, decreasing expression of the insulin-like growth factor I receptor is correlated with increasing WT1 expression. Our results demonstrate that expression of WT1 is induced in specific cell types during RA-induced differentiation of P19 EC cells, reflecting the tissue-specific expression of WT1 in vivo. Therefore, we believe that P19 EC cells are a suitable system to study activation and function of WT1 during differentiation

Possible Observation of Photon Speed Energy Dependence

Current constraints on photon velocity variability are summarized and displayed in terms of an energy dependent vacuum refraction index. It is shown that the energy-momentum balance of high energy Compton scattering is very sensitive to the outgoing photon speed. A missing energy observation in HERA Compton polarimeter data indicates that photons with 12.7 GeV energy are moving faster than light by 5.1(1.4)mm/s. An asymmetry spectrum measured by the SLC longitudinal polarimeter implies however an effect which is 42 times smaller, although the interpretation of the data is less clear here.Comment: 13 pages, 3 figure

Can Light Signals Travel Faster than c in Nontrivial Vacuua in Flat space-time? Relativistic Causality II

In this paper we show that the Scharnhorst effect (Vacuum with boundaries or a Casimir type vacuum) cannot be used to generate signals showing measurable faster-than-c speeds. Furthermore, we aim to show that the Scharnhorst effect would violate special relativity, by allowing for a variable speed of light in vacuum, unless one can specify a small invariant length scale. This invariant length scale would be agreed upon by all inertial observers. We hypothesize the approximate scale of the invariant length.Comment: 12 pages no figure

Scharnhorst effect at oblique incidence

We consider the Scharnhorst effect (anomalous photon propagation in the Casimir vacuum) at oblique incidence, calculating both photon speed and polarization states as functions of angle. The analysis is performed in the framework of nonlinear electrodynamics and we show that many features of the situation can be extracted solely on the basis of symmetry considerations. Although birefringence is common in nonlinear electrodynamics it is not universal; in particular we verify that the Casimir vacuum is not birefringent at any incidence angle. On the other hand, group velocity is typically not equal to phase velocity, though the distinction vanishes for special directions or if one is only working to second order in the fine structure constant. We obtain an ``effective metric'' that is subtly different from previous results. The disagreement is due to the way that ``polarization sums'' are implemented in the extant literature, and we demonstrate that a fully consistent polarization sum must be implemented via a bootstrap procedure using the effective metric one is attempting to define. Furthermore, in the case of birefringence, we show that the polarization sum technique is intrinsically an approximation.Comment: 11 pages double-column format, 2 figures, RevTeX 4.0 (beta 2). Final versio

Geometrical aspects of light propagation in nonlinear electrodynamics

We analyze the propagation of light in the context of nonlinear electrodynamics, as it occurs in modified QED vacua. We show that the corresponding characteristic equation can be described in terms of a modification of the effective geometry of the underlying spacetime structure. We present the general form for this effective geometry and exhibit some new consequences that result from such approach.Comment: LaTex, 11 pages, accepted for publication in Phys. Rev.

Spontaneous emission between an unusual pair of plates

We compute the modification in the spontaneous emission rate for a two-level atom when it is located between two parallel plates of different nature: a perfectly conducting plate $(\epsilon\to \infty)$ and an infinitely permeable one $(\mu\to \infty)$. We also discuss the case of two infinitely permeable plates. We compare our results with those found in the literature for the case of two perfectly conducting plates.Comment: latex file 4 pages, 4 figure