ABSTRACT
Coordination cages obtained upon complexation of pyridyl functionalized porphyrins by Ag+ disassemble when overtaking a 1 : 2 stoichiometric amount of silver salt. An excess of Ag+ then leads to unusual chemical processes, here analyzed in detail, which permanently transform the monomeric porphyrins. The observed processes, discussed with reference to model compounds devoid of polyether substituted pyridyl residues, evidence a peculiar reactivity for meso 2,6-dimethylphenyl substituted porphyrins.
ABSTRACT
The anatomy and embryology of the aortic arch and its branching tributaries (brachiocephalic trunk, left common carotid artery and left subclavian artery) in man and animals are well substantiated. However, the anatomical variations and morphometry of the aortic arch and its branching tributaries in rat fetus at the 21st gestation day have not been studied. Pregnant rats were hysterectomized and the arterial systems of 114 fetuses were injected with a polymerisable resin through the umbilical artery. After maceration, the vascular casts were dissected out and prepared for observations under a scanning electron microscope (SEM). The resulting SEM pictures were studied with a picture analyser and different vessel parameters (diameters, lengths and angles) were measured. The success rate of the microvascular cast injection was 46.5%. Out of the 53 observed aortic arch casts, 98.1% showed the classical branching pattern and one (1.9%) had no brachiocephalic trunk. Morphological analysis showed many differences, which were not linked to the litter. The statistical processing of the measurements enabled us to determine that the aorta diameter after the branching of the left subclavian artery was the most replicable parameter. Moreover, the results revealed some strong correlations between different parameters. There are probably no discrete categories among the various observed parameters as diameters and angles. Some parameters show very little variability and can thus be used as reference points for further studies such as the comparison of a control population with a population treated with a relevant xenobiotic.
Subject(s)
Aorta, Thoracic/embryology , Brachiocephalic Trunk/embryology , Carotid Artery, Common/embryology , Fetus/anatomy & histology , Neovascularization, Physiologic/physiology , Subclavian Artery/embryology , Age Factors , Animals , Body Patterning/physiology , Corrosion Casting/methods , Female , Gestational Age , Male , Microscopy, Electron, Scanning , Pregnancy , Rats , Rats, Sprague-Dawley , Reference ValuesABSTRACT
Bruton tyrosine kinase (Btk) plays a crucial role in the differentiation of B lymphocytes and belongs to the group of Tec kinases, which are characterised by the presence of a pleckstrin homology domain. Here we show that Btk is activated and undergoes tyrosine phosphorylation upon challenge of platelet thrombin receptor, these responses requiring engagement of alphaIIb/beta3 integrin and phosphoinositide 3-kinase activity. These data unravel a novel signalling pathway involving Btk downstream of an adhesive receptor via a complex regulation implicating the products of phosphoinositide 3-kinase, which might act to anchor Btk at the membrane.
Subject(s)
Blood Platelets/metabolism , Phosphatidylinositol 3-Kinases/metabolism , Platelet Glycoprotein GPIIb-IIIa Complex/metabolism , Protein-Tyrosine Kinases/metabolism , Thrombin/pharmacology , Agammaglobulinaemia Tyrosine Kinase , Blood Platelets/drug effects , Enzyme Activation , Humans , Phosphorylation , Platelet Activation , Signal TransductionABSTRACT
Using a specific polyclonal anti-Tec antibody, we have shown that Tec is expressed in human platelets. In addition, Tec was found to undergo tyrosine phosphorylation during platelet activation. The phosphorylation increased after 1 min and remained stable after 3 min of thrombin treatment. The tetrapeptide RGDS inhibited more than 90% of thrombin-induced tyrosine phosphorylation of Tec and blocked its translocation to the cytoskeleton. These results suggest that Tec participates in platelet signaling downstream of integrin activation.