The bimodal regulation of vascular function by superoxide anion: role of endothelium

Reactive oxygen species (ROS) are implicated in vascular homeostasis. This study investigated whether O(2) (*-), the foundationmolecule of all ROS, regulates vasomotor function. Hence, vascular reactivity was measured using rat thoracic aortas exposed to an O(2) (*-) generator (pyrogallol) which dose-dependently regulated both alpha-adrenergic agonist-mediated contractility to phenylephrine and endothelium-dependent relaxations to acetylcholine. Pyrogallol improved and attenuated responses to acetylcholine at its lower (10 nM - 1 microM) and higher (10 - 100 microM) concentrations, respectively while producing the inverse effects with phenylephrine. The endothelial inactivation by L-NAME abolished acetylcholine-induced vasodilatations but increased phenylephrine and KCl-induced vasoconstrictions regardless of the pyrogallol dose used. Relaxant responses to sodium nitroprusside, a nitric oxide donor, were not affected by pyrogallol. Other ROS i.e. peroxynitrite and H(2)O(2) that may be produced during experiments did not alter vascular functions. These findings suggest that the nature of O(2) (*-)-evoked vascular function is determined by its local concentration and the presence of a functional endothelium.     

Temporal restriction of migratory and lineage potential in rhombomere 1 and 2 neural crest

Migratory cranial neural crest cells differentiate into a wide range of cell types, such as ectomesenchymal tissue (bone and connective tissues) ventrally in the branchial arches and neural tissue (neurons and glia) dorsally. We investigated spatial and temporal changes of migration and differentiation potential in neural crest populations derived from caudal midbrain and rhombomeres 1 and 2 by back-transplanting cells destined for the first branchial arch and trigeminal ganglion from HH8-HH19 quail into HH7-HH11 chicks. Branchial arch cells differentiated down ectomesenchymal lineages but largely lost both the ability to localize to the trigeminal position and neurogenic differentiation capacity by HH12-HH13, even before the arch is visible, and lost long distance migratory ability around HH17. In contrast, neural crest-derived cells from trigeminal ganglia lost ectomesechymal differentiation potential by HH17. Despite this, they retain the ability to migrate into the branchial arches until at least HH19. However, many of the neural crest-derived trigeminal ganglia cells in the branchial arch localized to the non-neural crest core of the arch from HH13 and older donors. These results suggest that long distance migration ability, finer scale localization, and lineage restriction may not be coordinately regulated in the cranial neural crest population.     

The neural crest: basic biology and clinical relationships in the craniofacial and enteric nervous systems

The highly migratory, mesenchymal neural crest cell population was discovered over 100 years ago. Proposals of these cells' origin within the neuroepithelium, and of the tissues they gave rise to, initiated decades-long heated debates, since these proposals challenged the powerful germ-layer theory. Having survived this storm, the neural crest is now regarded as a pluripotent stem cell population that makes vital contributions to an astounding array of both neural and non-neural organ systems. The earliest model systems for studying the neural crest were amphibian, and these pioneering contributions have been ably refined and extended by studies in the chick, mouse, and more recently the fish to provide detailed understanding of the cellular and molecular mechanisms regulating and regulated by the neural crest. The key questions regarding control of craniofacial morphogenesis and innervation of the gut illustrate the wide range of developmental contexts in which the neural crest plays an important role. These questions also focus attention on common issues such as the role of growth factor signaling in neural crest cell development and highlight the central role of the neural crest in human congenital disease.     

GBSX: a toolkit for experimental design and demultiplexing genotyping by sequencing experiments

Background

Massive parallel sequencing is a powerful tool for variant discovery and genotyping. To reduce costs, sequencing of restriction enzyme based reduced representation libraries can be utilized. This technology is generally referred to as Genotyping By Sequencing (GBS). To deal with GBS experimental design and initial processing specific bioinformatic tools are needed.

Results

GBSX is a package that assists in selecting the appropriate enzyme and the design of compatible in-line barcodes. Post sequencing, it performs optimized demultiplexing using these barcodes to create fastq files per barcode which can easily be plugged into existing variant analysis pipelines. Here we demonstrate the usability of the GBSX toolkit and demonstrate improved in-line barcode demultiplexing and trimming performance compared to existing tools.

Conclusions

GBSX provides an easy to use suite of tools for designing and demultiplexing of GBS experiments.     

Solid phase synthesis and SAR of small molecule agonists for the GPR40 receptor

The discovery, synthesis and structure-activity relationship (SAR) of novel carboxylic acid agonists for GPR40 are described. Aryl propionic acid 1, identified from a high throughput screen, was selected for chemical exploration. Compound 2 was identified as our lead molecule through efficient solid phase combinatorial array chemistry and had an attractive in vitro and in vivo pharmacokinetic profile in rat. These ligands may prove useful in establishing a role for GPR40 in insulin regulation.     

Effects of lung volume on lung and chest wall mechanics in rats

To investigate the effect of lung volume onchest wall and lung mechanics in the rats, we measured theimpedance (Z) under closed- and open-chest conditions at variouspositive end-expiratory pressures (0-0.9 kPa) by using acomputer-controlled small-animal ventilator (T. F. Schuessler andJ. H. T. Bates. IEEE Trans. Biomed. Eng. 42: 860-866, 1995) that we have developed fordetermining accurately the respiratory Z in small animals. The Z oftotal respiratory system and lungs was measured with small-volumeoscillations between 0.25 and 9.125 Hz. The measured Z was fitted to amodel that featured a constant-phase tissue compartment (withdissipation and elastance characterized by constantsG andH, respectively) and a constant airwayresistance (Z. Hantos, B. Daroczy, B. Suki, S. Nagy, and J. J. Fredberg. J. Appl.Physiol. 72: 168-178, 1992). We matched the lungvolume between the closed- and open-chest conditions by using thequasi-static pressure-volume relationship of the lungs to calculate Zas a function of lung volume. Resistance decreased with lung volume andwas not significantly different between total respiratory system andlungs. However, G andH of the respiratory system weresignificantly higher than those of the lungs. We conclude that chestwall in rats has a significant influence on tissue mechanics of thetotal respiratory system.

     

Physiological and Endocrinological Responses During Prolonged Exercise in Hatchery-Reared Rainbow Trout (Oncorhynchus mykiss)

Rainbow trout (Oncorhynchus mykiss) were subjected to vigorous exercise (1.5 body length s−1), low exercise (0.5 body length s−1) or still-water (0.0 body length s−1). Hematocrit, glucose, growth hormone (GH), Cortisol and triiodo-L-thyronine (T3) were monitored at the start of exercise, after 24 h, and after 2, 4, 8, 16 and 32 days of continuous swimming. Morphological indices and food intake were also monitored. At the end of the experiment, trout subjected to low exercise had gained significantly (p<0.05) more weight than both the control (still-water) and vigorously exercised fish. This low exercised group of fish also consumed more food than the 2 other groups. Hematocrit increased significantly in both exercised groups at the onset of swimming but returned to pre-exercise levels within 8 hrs. Plasma glucose appeared to be generally unaffected by exercise. Likewise, plasma concentrations of both GH and T3 were not influenced by exercise. Plasma Cortisol levels increased in an exercise dependent fashion at the onset of swimming, but returned to pre-swimming levels within 24 h and there was no apparent effect of sustained swimming. The results suggest: (i) the onset of exercise elicits transient changes in plasma components, (ii) the observed weight gain in low exercising salmonids occur without increases in circulating levels of GH or T3.     

Inhibition of NADH oxidation by pyridine derivatives

The neurotoxicity of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine, an impurity in an illicit drug, is expressed after its oxidation to 1-methyl-4-phenylpyridinium by monoamine oxidase. The pyridinium is concentrated by carrier-mediated transport into the mitochondria where it inhibits NADH dehydrogenase and, hence, ATP synthesis. Some structurally related compounds have been tested for their effect on the oxidation of NAD+-linked substrates in intact mitochondria, and for the inhibition of the accumulation of the pyridinium into mitochondria and of NADH dehydrogenase activity in a membrane preparation. Some pyridine derivatives are more inhibitory to NADH dehydrogenase than is 1-methyl-4-phenylpyridinium but these are not concentrated into mitochondria by the uptake system. 4-Phenylpyridine, one of the most effective inhibitors, both occurs naturally and is an environmental pollutant.