Intravascular signal in MR imaging: use of phase display for differentiation of blood-flow signal from intraluminal disease

Intravascular signal from flowing blood is frequently observed on magnetic resonance (MR) images and may be indistinguishable from partial or complete vascular occlusion caused by thrombus or tumor. With a phase-display reconstruction method, qualitative assessment of large-vessel patency within the abdomen was undertaken in 15 healthy subjects and 12 patients with angiographically or surgically documented intravascular thrombus or tumor. Computed tomographic (CT) scans were available in all patients for correlation. MR studies were performed with a multisection spin-echo pulse sequence and two-dimensional Fourier transform spatial encoding. Data acquired from a single sequence was reconstituted in two ways to provide both routine anatomic images and a pictorial representation of large-vessel flow on a phase-sensitive image. With this method, reliable and easy differentiation of intraluminal thrombus and tumor from blood flow signal within large vessels was achieved. Information from these phase-display images compared favorably with findings from angiography and contrast-enhanced CT in the determination of luminal patency and obstruction.     

P2X (purinergic) receptor distributions in rat blood vessels

The distribution of purinergic (P2X1 and P2X2) receptors on smooth muscle cells in relation to autonomic nerve varicosities in rat blood vessels has been determined using immunofluorescence and confocal microscopy. P2X1 and P2X2 receptors were visualised using rabbit polyclonal antibodies against the extracellular domain of the receptors and varicosities visualised using a mouse monoclonal antibody against the ubiquitous synaptic vesicle proteoglycan SV2. Two size classes of P2X1 receptor clusters were observed on the smooth muscle cells of mesenteric, renal, and pulmonary arteries as well as in the aorta and in veins: a large approximately elliptical cluster 1.32+/-0.21 microm long and 0.96+/-0.10 microm in diameter; and a smaller spherical cluster with a diameter of 0.32+/-0.05 microm. The latter occurred throughout the media of arteries of all sizes, whereas the former were restricted to the adventitial surface of the media and to endothelial cells, except for the pulmonary artery, in which large receptor clusters were found throughout the media of the vessel. At the adventitial surface, the large clusters are in general located beneath SV2 labelled varicosities. None of the small clusters was associated with varicosities. Three-dimensional reconstruction of the P2X and SV2 labelling at individual varicosities showed that the varicosities were immediately apposed to the P2X receptor clusters. P2X2 receptors were located on nerves and on endothelial cells. They were also found in low density on the smooth muscle cells in the media. These observations are discussed in relation to the mechanism of purinergic transmission to the smooth muscle cells of blood vessels.     

The Na+-dependent binding of [3H]l-aspartate in thaw-mounted sections of rat forebrain

Binding of [³H]l-aspartate to thaw-mounted coronal sections of frozen rat forebrain was strong in grey regions of telencephalon (neocortex, hippocampus and neostriatum), but it was weaker and unevenly distributed in diencephalon. At low nanomolar concentrations of ligand used in the present studies, [³H]l-aspartate binding was strongly inhibited by l-threo-3-hydroxyaspartate and l-trans-pyrrolidine-2,4-dicarboxylate, compounds known to be substrate/inhibitors of the high affinity uptake of l-glutamate and l-aspartate. None of the typical ligands for the glutamate and aspartate receptors, 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX), N-methyl-d-aspartate and kainate, produced a strong enough inhibition (only CNQX at 100 M weakly inhibited) of the Na⁺-dependent [³H]l-aspartate binding to suggest that [³H]l-aspartate was bound to the receptor binding sites. Furthermore, the binding was absolutely dependent on the presence of Na⁺ in the incubation medium. It is concluded that [³H]l-aspartate is a ligand suitable for autoradiographic studies of the distribution of Na⁺-dependent, high affinity uptake of acidic amino acids in the central nervous system (CNS). However, feasibility of using [³H]l-aspartate as a specific marker of glutamatergic and/or aspartergic synapses in the CNS requires further investigation.     

Indications for induction of labour: a best-evidence review

Background  Rates of labour induction are increasing.
Objectives  To review the evidence supporting indications for induction.
Search strategy  We listed indications for labour induction and then reviewed the evidence. We searched MEDLINE and the Cochrane Library between 1980 and April 2008 using several terms and combinations, including induction of labour, premature rupture of membranes, post-term pregnancy, preterm prelabour rupture of membranes (PROM), multiple gestation, suspected macrosomia, diabetes, gestational diabetes mellitus, cardiac disease, fetal anomalies, systemic lupus erythematosis, oligohydramnios, alloimmunization, rhesus disease, intrahepatic cholestasis of pregnancy (IHCP), and intrauterine growth restriction (IUGR). We performed a review of the literature supporting each indication.
Selection criteria  We identified 1387 abstracts and reviewed 418 full text articles. We preferentially included high-quality systematic reviews or large randomised trials. Where no such studies existed, we included the best evidence available from smaller randomised trials and observational studies.
Main results  We included 34 full text articles. For each indication, we assigned levels of evidence and grades of recommendation based upon the GRADE system. Recommendations for induction of labour for post-term gestation, PROM at term, and premature rupture of membranes near term with pulmonary maturity are supported by the evidence. Induction for IUGR before term reduces intrauterine fetal death, but increases caesarean deliveries and neonatal deaths. Evidence is insufficient to support induction for women with insulin-requiring diabetes, twin gestation, fetal macrosomia, oligohydramnios, cholestasis of pregnancy, maternal cardiac disease and fetal gastroschisis.
Authors' conclusions  Research is needed to determine risks and benefits of induction for many commonly advocated clinical indications.