Isoforms measurement

F.J. Legros, V. Nuyens, E. Minet, P. Emonts, K.Z. Boudjeltia, A. Courbe, J.L. Ruelle, J. Colicis, F. de L Escaille and J.P. Henry, Carbohydrate-deficient transferrin isoforms measured by capillary zone electrophoresis for detection of alcohol abuse, Clin. Chem., 48, 2177-2186 (2002). 

Legros, F.J. et al.. Carbohydrate-deficient transferrin isoforms measured by capillary zone electrophoresis for detection of alcohol abuse, Clin. Chem., 48, 2177, 2002. 

The measurement of ER has become a standard assay in the clinical management of breast cancer. The presence of ERa identifies those breast cancer patients with a lower risk of relapse and better clinical outcome. Receptor status also provides a guideline for those tumors that may be responsive to hormonal intervention. But only about half of ER-positive patients respond to hormonal therapies. Of those who respond initially, most will eventually develop an estrogen unresponsive disease following a period of treatment even though ERa is often still present. Mutant receptors and constitutively active r eceptors as well as hormone-independent activation of the ERa are discussed. The involvement of ER 3 isoforms is under investigation. 

FRET probes have not only been generated to measure the phospholipase activity but to study its substrate specificity as well. Several substrates of PLA2 with a variety of head groups and labeled with a BODIPY dye and a Dabcyl quencher were created by Rose et al. and tested against different PLAs in cells to determine substrate specificity and intracellular localization [137], The specificity of PLA2 isoforms towards the number of double bonds in the sn2 position was evaluated with a small series of PENN derivatives. It was demonstrated that the cytosolic type V PLA2 preferred substrates with a single double bond [138],... 

FRET is an extremely useful phenomenon when it comes to the analysis of molecular conformations and interactions. F or the analysis of interactions, in which two separate molecules are labeled with an appropriate pair of fluorophores, an interaction can be shown by observing FRET. Further, FRET can be used as a type of spectroscopic ruler to measure the closeness of interactions. Proteins, lipids, enzymes, DNA, and RNA can all be labeled and interactions documented. This general method can be applied not only to questions of cellular function like kinase dynamics [3] but also to disease pathways, for example, the APP-PS1 interaction that is important in Alzheimer s disease (AD) [4], Alternatively, two parts of a molecule of interest can be labeled with a donor and acceptor fluorophore. Using this technique, changes in protein conformation and differences between isoforms of proteins can be measured, as well as protein cleavage. 

The cellular and subcellular distributions of a-subunit isoforms provide clues to their different physiological functions. The four isoforms exhibit about 85% sequence identity. The most substantial differences occur in their N-terminal regions and in an 11-residue sequence of the large cytoplasmic loop. When measured in cell cultures, the isoforms differ in their apparent affinities for intracellular Na+ (al < a2 < a3) [21 ] and extracellular K+ (a3 < a2 = al) [22], In adult tissues, al is the major iso form in... 

An optimal Lp(a) assay requires specific antibodies that cross-react neither with plasminogen nor with apo-B and that recognize all apo(a) isoforms (D17, G32, L7). The assay must be sensitive enough to measure the lowest range of Lp(a) levels, and it may not be dependent upon the size of the different apo(a) isoform(s) present in the sample. 

Electroimmunoassay (rocket electrophoresis) and radial immunodiffusion (A5) lack sensitivity at low Lp(a) concentrations, and the response is influenced by the size of the apo(a) isoforms (A5, K28). Differences in migration velocity in the agarose gel lead to an underestimation of the samples with large apo(a) isoforms and to an overestimation of samples with small apo(a) isoforms. Moreover, the detection limit lies around 0.07-0.08 g/liter Lp(a), so that this method is better suited for screening and detection of individuals with elevated Lp(a) levels than for the exact measurement of the plasma Lp(a) concentration. 

The aim of this study is to measure the effect of EGb 761 versus placebo on the ratio of the isoform of the protein precursor of beta amyloid platelets, in patients with mild to moderate Alzheimer s disease. 

Official Title Effect of EGb 761 on the Ratio of the Isoforms of the Protein Precursor of Beta Amyloid Platelets on Patients With Mild to Moderate Alzheimer s Disease. A Phase II, Randomized, Double-Blind Trial, on Parallel Groups Versus Placebo Primary Outcome Measures Effect of EGb 761 on the ratio of the isoform of the protein precursor of beta amyloid platelets Secondary Outcome Measures Efficacy of EGb 761 on the cognitive functions and safety of EGb 761 at a dosage of 240 mg per day Total Enrollment 40 Study Start July 2005... 

Up to 5% of unstimulated CB mononuclear cells are CSF-1-receptor positive as measured by flow cytometry (data not shown). In the first week of coculture on transduced MMCF cells all CSF-1 isoforms promoted proliferation of CB CD34+ cells with comparable rates (Fig. 5a). However, within four weeks the stimulatory activity of wildtype CSF-1 declined dramatically. Obviously, the soluble isoform provided only a limited expansion of CB CD34+ cells. 

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