Biomedical subjects

A Torriglia

Publications and source records attributed to A Torriglia.

23 records · Page 2Linked to original sources

PubMed1992

Purification of an active receptor for acidic and basic fibroblast growth factor from bovine retina.

Acidic and basic fibroblast growth factors (FGFs) influence cell division and differentiation in retina cells. Their effects are thought to be mainly mediated through stimulation of a specific membrane receptor and subsequent generation of an intracellular signal pathway. In this study, we purified a FGF receptor of 130 kDa from bovine neural retina using wheat germ agglutinin affinity chromatography followed by FGF-affinity chromatography. The isolated receptor showed ligand binding activity with dissociation constants of 0.8 nM and 2 nM for aFGF and bFGF, respectively. Furthermore, binding of aFGF and bFGF to purified receptor resulted in self-phosphorylation, demonstrating that the isolated receptor had an unaltered intrinsic kinase activity.

Animals↗

PubMed1991

[FGF and physiopathological implications].

The role of FGF in retinal pathologies can be considered in two respects: 1-as a causative agent (for instance, stimulating aberrant growth or abnormally affecting some aspects of cellular behaviour), or 2-as a possible therapeutic drug (for instance, its ability to rescue neuronal cells from programmed or surgically-induced death), there is evidence for both: the retina, particularly the photoreceptors (PR), seems to be highly succeptible to a host of genetic defects, for instance, in the rat mutant RCS a defect in the pigmented epithelial cells (RPE) leads to the destruction of the PR. Transocular injection of FGF into RCS rats reduces the rate of PR cell loss. On the other hand, we have recently identify a difference in FGF-Receptor cell biology in the RCS mutant which may underline this particular dystrophy. Cultures of purified RPE cells were established from the dystrophic RCS rat and its congenic normal sighted control, and the number and affinity of cell surface FGF-R determined by incubation with 125I-bFGF. Scatchard analysis of the bining data indicated that whereas affinites were in both strains around 60pM, there was a large reduction in receptor number, about 70% in the mutant. Analysis of other FGF/FGF-R criteria, such as mitogenic activity, receptor molecular weight and the profile of FGF degradatoin showed no significant differences between the strains. Thus, defects in the FGF/FGF-R regulating system may actually led to retinal degeneration (RCS rat). But, once again, the underlying principles of FGF mechanisms of action in vivo are at present too incompletely understood to permit rationalization of these various observations.

Animals↗

PubMed1990

Related fibroblast growth factor receptor genes exist in the human genome.

We have isolated, from a human tumor cDNA library, a gene encoding a putative receptor-like protein-tyrosine kinase that we call TK14. The amino acid sequence of the TK14 protein is closely related to the available partial sequence of the mouse protein bek, and more distantly related to the sequences of a chicken basic fibroblast growth factor receptor (73% sequence homology) and the apparent human equivalent of this receptor, the FLG protein (encoded by the fms-like tyrosine kinase gene). Overexpression of the TK14 protein by transfection of COS-1 cells with the corresponding cDNA in a simian virus 40-based expression vector leads to the appearance of new cell-surface binding sites for both acidic and basic fibroblast growth factors. This has been demonstrated by specific binding assays and chemical cross-linking experiments using 125I-labeled growth factors. It appears, therefore, that the human genome contains at least two distinct genes, for TK14 and FLG, that code for related fibroblast growth factor receptors.

Amino Acid Sequence↗

PubMed1988

A method for the determination of inorganic phosphate in the presence of labile organic phosphate and high concentrations of protein: application to lens ATPases.

We present here an improvement in the classical molybdate method for inorganic phosphate determination. This method has high sensitivity, with 1 nmol of Pi giving an absorbance change of 0.060 A850 unit. It is highly reproducible and the color remains stable for at least 3.5 h. In addition the use of sodium dodecyl sulfate makes it possible to stop enzymatic reactions without organic phosphate hydrolysis. It also shows an extremely low interference by highly concentrated solutions of different origins. Of special interest is its high tolerance to protein, permitting as much as 50 mg/ml of human serum protein in the sample without precipitation or color interference. For these reasons, it proves to be very useful in the determination of ATPases in tissues such as the ocular lens with low specific activity.

Animals↗

PubMed1988

The effect of near-UV light on Na-K-ATPase of the rat lens.

The influence of in vitro near-UV radiation exposure on the physical state of the rat lens and on its membrane-bound Na-K-ATPase activity was investigated. Lens swelling was correlated to the appearance of opacities and the inactivation of the enzyme. The results show a significant decrease in the Na-K-ATPase activity which may be an early change leading to osmotic type cataracts. The dose-effect curves obtained for cortical and epithelial enzymes were different. Since the data do not follow a monoexponential function, the existence of two forms of Na-K-ATPase in the lens is discussed.

Animals↗