Identifying molecular markers associated with classification of genotypes by External Logistic Biplots.

UNLABELLED: For characterization of genetic diversity in genotypes several molecular techniques, usually resulting in a binary data matrix, have been used. Despite the fact that in Cluster Analysis (CA) and Principal Coordinates Analysis (PCoA) the interpretation of the variables responsible for grouping is not straightforward, these methods are commonly used to classify genotypes using DNA molecular markers. In this article, we present a novel algorithm that uses a combination of PCoA, CA and Logistic Regression (LR), as a better way to interpret the variables (alleles or bands) associated to the classification of genotypes. The combination of three standard techniques with some new ideas about the geometry of the procedures, allows constructing an External Logistic Biplot (ELB) that helps in the interpretation of the variables responsible for the classification or ordination. An application of the method to study the genetic diversity of four populations from Africa, Asia and Europe, using the HapMap data is included. AVAILABILITY: The Matlab code for implementing the methods may be obtained from the web site: http://biplot.usal.es.

Chronic exposure to cigarette smoke extract impairs endothelium-dependent relaxation of chicken embryo pulmonary arteries.

Maternal smoking may increase the risk for various adverse neonatal outcomes including persistent pulmonary hypertension of the newborn (PPHN). We investigated whether chronic prenatal cigarette smoke extract (CSE) exposure could produce abnormal vasoreactivity in pulmonary arteries. Daily injections of CSE (diluted in phosphate buffered saline) or vehicle were added to the air cells of fertilized eggs starting on day 5 of the 21-day incubation period of the chicken embryo. On day 19, pulmonary arteries were dissected out and their contractile properties were assessed using small vessel myography. Endothelium-dependent and endothelium-independent vasorelaxations were examined by using acetylcholine (ACh, 10(-8) to 10(-4) M) and sodium nitroprusside (SNP, 10(-8) to 10(-4) M), respectively. The drug concentration inducing 50% of the maximal relaxation was determined for each concentration-response curve and expressed as negative log molar (pD(2)). Exposure to CSE significantly decreased the sensitivity of pulmonary arteries to ACh (pD(2) control group: 7.29 +/- 0.24; pD(2) CSE-exposed group 6.24 +/- 0.12, p < 0.05). SNP elicited similar responses in vessels of both groups at all tested concentrations. In conclusion, chronic prenatal exposure to CSE impaired endothelium-dependent but not endothelium-independent vasodilation in chicken embryo pulmonary arteries. This observation suggests that cigarette smoke components may produce deleterious effects on fetal vascular endothelial vasorelaxant pathways, leading to the development of adverse outcomes such as PPHN.

Alpha 1-adrenoceptor subtypes in rat aorta and mesenteric small arteries are preserved during left ventricular dysfunction post-myocardial infarction.

OBJECTIVE: In heart failure, homologous downregulation of beta-adrenoceptors contributes to impaired adrenergic responsiveness of the myocardium. We evaluated alpha 1-adrenoceptors (alpha 1-AR) in a sparsely innervated and a densely innervated peripheral artery in an experimental model of left ventricular dysfunction post-myocardial infarction. METHODS: [3H]Prazosin binding was determined in arterial segments of Wistar-Kyoto rats (WKY), and of Wistar rats 5 weeks after myocardial infarction (MI) or sham operation (SHAM). RESULTS: In the thoracic aorta (TAO) of WKY, specific prazosin binding was: (i) prevented by the irreversible alpha 1B-AR and relatively selective alpha 1D-AR antagonist, chloroethylclonidine (CEC); (ii) displaced with low affinity (pKi 6.25) by the alpha 1A-AR selective ligand, (+)-niguldipine; and (iii) displaced with both high (pKi 10.4) and low (pKi 7.37) affinity by the alpha 1D-AR antagonist, BMY 7378. In mesenteric small arteries (MSA) of WKY, prazosin binding was: (i) reduced 50% by CEC; (ii) displaced in a biphasic fashion by (+)-niguldipine (pKi 8.60 and pKi 6.22); and (iii) displaced by BMY 7378 with low affinity only (pKi 6.86). Also in TAO of SHAM. prazosin binding was prevented by CEC, but neither 30 nM (+)-niguldipine nor 1 nM BMY 7378 affected it. In MSA of SHAM, prazosin binding was virtually abolished in the presence of 30 nM (+)-niguldipine and was not reduced by 1 nM BMY 7378. In TAO and MSA of MI, compared to SHAM, the density of binding sites tended to be increased rather than decreased and neither the affinity for the ligand nor the effects of alpha 1-AR subtype selective tools were significantly modified. CONCLUSIONS: These findings indicate that: (i) radioligand binding can be applied in intact arterial segments to quantify and characterize alpha 1-AR; (ii) although differences seem to exist between rat strains, alpha 1B-AR and alpha 1D-AR predominate in rat thoracic aorta and alpha 1A-AR and alpha 1B-AR in mesenteric small arteries; and (iii) alpha 1-AR density is not reduced in the poorly innervated aorta and the densely innervated mesenteric small arteries of rats with heart failure due to myocardial infarction.

Computers create new perspectives in radiotherapy.

In diagnostic radiology a revolution has taken place over the last decade with the development of computer-based imaging (CT, MR). Such technologies are now available routinely even in medium-sized radiology departments. In radiotherapy departments, however, computer applications have often been limited to calculation of dose distributions on CT images and administrative tasks. The last few years applications are emerging and utilize the full power of modern computer technology and promise to revolutionize treatment planning and execution in everyday radiotherapy. The authors present their view on some of these applications and the way they may push ahead frontiers in clinical radiotherapy.

Transbrachial approach for aortic and selective supraaortic vessel catheterization using a safe and easy technique to reform the Simmons II catheter tip.

A total of 286 patients (158 outpatients) were examined by intra-arterial DSA in the evaluation of cerebrovascular disease using a transbrachial approach. In all cases a 5F introducer sheath, a 5F pigtail catheter for aortic arch injection and a 5F Simmons II catheter for selective catheterization were used. Excellent demonstration of aortic arch and supraaortic arteries (including intracranial circulation) was obtained (92.2-100%). The complication rate was favorable, with only one major complication (thrombosis of an axillary artery). The use of an introducer sheath minimizes local complications and vessel wall damage during catheter exchange. Aortic arch injection must always be performed prior to selective catheterization. The results of selective catheterization prove the suitability of the Simmons II catheter, whose typical shape was easily and safely obtained using the configuration of the pigtail catheter and a 180 cm long guide wire for catheter exchange. Using the technique as described, the transbrachial approach is a safe and easy way for optimal vascular evaluation in cerebrovascular disease, especially useful in outpatients.

Properties of the 120,000- and 95,000-dalton actin-binding proteins from Dictyostelium discoideum and their possible functions in assembling the cytoplasmic matrix.

The cell cortex of Dictyostelium amebae contains an actin-rich cytoplasmic matrix. Changes in geometry of this matrix are believed to regulate protrusive activity and motility of the cell cortex. Two actin-binding proteins (120,000 and 95,000 daltons [120K and 95K]) are present in the cell cortex, and their properties, many of which are described here for the first time, suggest that they regulate growth and organization of cortical microfilaments. The 120K protein is a flexible dimer 35 nm in length with a native molecular mass of 241,000. It nucleates the polymerization of actin and crosslinks the filaments to form branched networks like those seen in situ in the cell cortex. The production of a branched network of short crosslinked filaments results in a lattice that would theoretically generate the maximum rigidity with minimum amount of polymer. This sort of lattice would be very useful as a space-filling cytoskeleton capable of resisting deformation. The 120K protein inhibits the actin-stimulated Mg ATPase of myosin. Competition for actin binding between 120K and myosin, the impenetrability of the 120K-actin network to myosin, and the rigidity of actin filaments that are crosslinked by 120K could all contribute to the decrease in the actin-stimulated Mg ATPase of myosin. The properties of 120K are consistent with a role for this protein in regulating the site of actin filament growth and gelation in the cell but not the assembly of actin-containing structures that would participate in force generation by a sliding-filament mechanism involving myosin. The 95K protein is a rigid dimer 40 nm in length with a native molecular mass of between 190,000 and 210,000. Its physical and antigenic properties lead us to conclude that the 95K protein is Dictyostelium alpha-actinin. Unlike 120K, it crosslinks actin filaments into lateral arrays and increases the actin-stimulated Mg ATPase of myosin. Both activities are regulated by Ca2+. The properties of 95K are consistent with a role in organizing actin filaments in the cell into lateral arrays that are capable of efficient interaction with myosin to produce force for cell motility.

Identification of the vasopressin-neurophysin II and the oxytocin-neurophysin I producing neurons in the bovine hypothalamus.

Immuno-enzyme histochemical investigations on the bovine hypothalamus showed that vasopressin and oxytocin are synthetized in separate neurons. Moreover, it was found that the vasopressin-producing neurons are identical with the neruophysin II-producing neurons, while the oxtocin producing neurons correspond with the neurophysin I-producing neurons. From this result it is concluded that, in the species studied, neurophysin I is the carrier protein of oxytocin and that neurophysin II is the carrier protein of vasopressin. The bovine vasopressin-neurophysin II producing neurons and the oxytocin-neurophysin I producing neurons are both present as well in the suparoptic nuclei as in the paraventricular nuclei. In the supraoptic nuclei, the vasopressin-neurophysin II neurons predominate in number; in the paraventricular nuclei, the oxytocin-neurophysin II neurons predominate. The two kinds of bovine neurosecretory neurons are partly localized in separate areas. Moreover, the vasopressin-neurophysin II neurons and the oxytocin-neurophysin I neurons show distinct morphological differences.

Identification of the vasopressin-neurophysin producing neurons of the rat suprachiasmatic nuclei.

Immuno-enzyme histochemical investigations on the hypothalamus of the normal rat showed (1) that the suprachiasmatic nuclei produce vasopressin; (2) that it is highly probable that these nuclei do not produce oxytocin. From the present and previous investigations it may be concluded that the suprachiasmatic neurons produce a vasopressin-neurophysin complex.