87,628 research outputs found
Adrenocortical and adrenomedullary homologs in eight species of adult and developing teleosts: Morphology, histology, and immunohistochemistry
No full textMorphology, histology, and immunohistochemistry of the adrenocortical and adrenomedullary homologs (adrenal glands) of the following developing and adult teleosts were examined: Salmoniformes-Oncorhynchus mykiss (rainbow trout), Salmo trutta fario (brown trout), Coregonus lavaretus (white fish); Cyprinodontiformes-Gambusia affinis (mosquito fish). Perciformes-Dicentrarchus labrax (sea bass), Sparus aurata (sea bream), Diplodus sargus (white bream), Oblada melanura (saddled bream). The anatomical relationships of the gland with the renal system and venous vessels were also noted. in adults of all species steroidogenic and catecholaminergic chromaffin cells were found in the head kidney, which is pronephric in origin and subsequently transformed into a hematopoietic lymphatic organ. In Perciformes, chromaffin cells are distributed around the anterior and posterior cardinal veins and ducts of Cuvier; in Salmoniformes, around the posterior cardinal veins and in the hematopoietic tissue; and in G. affinis, around the ducts of Cuvier and posterior cardinal veins, while a few are visible also around the sinus venosus. in Perciformes and Salmoniformes, numerous chromaffin cells are also present in the posterior kidney, derived from the opisthonephros, in contact with the caudal vein. Steroidogenic cells are always confined to the head kidney. During development chromaffin and steroidogenic cells appear early after hatching in the pronephric kidney, at the level of the ducts of Cuvier and of the cephalic part of the posterior cardinal veins. Later, chromaffin cells in Perciformes reach the anterior cardinal veins, and subsequently, in both Perciformes and Salmoniformes, they reach the developing posterior kidney. Their localization along the posterior kidney is still in progress about 4 months after hatching and is completed about a year after hatching. These findings support the concept that the structure of the adrenal gland in teleosts is intermediate between that of the other actinopterygians and that of tetrapods. The development differs from that of tetrapods in that it occurs mainly in the pronephros and only later do chromaffin cells reach the opisthonephric kidney. (C) 1997 Academic Press
Correlazione tra affollamento degli incisivi inferiori, curva di Spee e disarmonia dento-facciale
No full textT-cell receptor (TCR) signal transduction: Biochemical mechanisms and possible clinical implications
No full textThe T-cell receptor (TCR) is a multiprotein complex composed of the Ti subunit responsible for antigen binding, the CD3 complex and the ζ family dimers involved in the TCR signal transduction. This function is mainly due to the presence of a 17 aminoacid motif, known as the ARAM (Antigen Recognition Activation Motifs) sequence, present in the cytoplasmic domains of the γ, δ, and ε chains of the CD3 complex and the ζ dimers. One of the earliest biochemical events after TCR cross-linking is the enhanced phosphorylation of several cellular substrates on tyrosine residues. Since the TCR/CD3 complex lacks intrinsic tyrosine kinase activity, five cytoplasmic protein tyrosine kinases (PTKs) belonging to three different families have been shown to be sequentially activated after TCR engagement: p56(lck) and p59(fyn) of the Src family, p70(zap) and p72(syk) of the Syk family and p50(csk) of the Csk family. p56(lck) interacts noncovalently with the cytoplasmic domains of the co-receptors CD4 and CD8, in helper and suppressor T cells, respectively; p59(fyn) has been shown to weakly associate directly with the TCR complex. The catalytic activity of the Src family kinases is regulated by the CD45 transmembrane phosphatase and the Csk cytosolic tyrosine-kinase. Both these enzymes act on the same C-terminal regulatory tyrosine residue of the Src-like PTKs. TCR stimulation rapidly induces tyrosine phosphorylation of p56(lck) and p59(fyn), whose most important cellular substrates are the ARAM sequences of the CD3 complex and the ζ chains. The phosphorylated ARAMs create the binding sites for the two SH2 domains of p70(zap), leading to p70(zap) activation. Even though p72(syk) is known to be activated after TCR stimulation, its exact temporal localization in the signaling cascade is not completely understood. Recruitment of downstream signal transducers, such as phospholipase C γ1 (PLCγ1) and Ras, follows p70(zap) activation. All these events lead to changes in gene expression, production of lymphokines and cell proliferation. This review focuses on the biochemical pathways activated by TCR engagement and on the posible clinic-therapeutic implications of the altered activity of the involved tyrosine-kinases
Correlazioni tra affollamento degli incisivi inferiori, curva di Spee e disarmonia dento-facciale
No full textPatologia infiammatoria dei mascellari da cause odontogene: etiopatogenesi e clinica (Dossier n.2)
No full text- …
