Objective-The role of fluid shear stress (FSS) in collateral vessel growth remains disputed and prospective in vivo experiments to test its morphogenic power are rare. Therefore, we studied the influence of FSS on arteriogenesis in a new model with extremely high levels of collateral flow and FSS in pig and rabbit hind limbs. Methods and Results-A side-to-side anastomosis was created between the distal stump of one of the bilaterally occluded femoral arteries with the accompanying vein. This clamps the collateral reentry pressure at venous levels and increases collateral flow, which is directed to a large part into the venous system. This decreases circumferential wall stress and markedly increases FSS. One week after anastomosis, angiographic number and size of collaterals were significantly increased. Maximal collateral flow exceeded by 2.3-fold that obtained in the ligature-only hind limb. Capillary density increased in lower leg muscles. Immunohistochemistry revealed augmented proliferative activity of endothelial and smooth muscle cells. Intercellular adhesion molecule-1 and vascular cell adhesion molecule (VCAM)-1 were upregulated, and monocyte invasion was markedly increased. In 2-dimensional gels, actin-regulating cofilin1 and cofilin2, destrin, and transgelin2 showed the highest degree of differential regulation. Conclusions-High levels of FSS cause a strong arteriogenic response, reinstate cellular proliferation, stimulate cytoskeletal rearrangement, and normalize maximal conductance. FSS is the initiating molding force in arteriogenesis. Key Words: fluid shear stress Ⅲ shunt Ⅲ arteriogenesis Ⅲ proteomics Ⅲ cytoskeletal proteins N umerous studies have documented the influence of fluid shear stress (FSS) as an arterial molding force, 1-3 but information on the actions of markedly increased in vivo FSS on the development of arterial collateral vessels after occlusion of a conduit artery is lacking. Such studies are needed because attempts at changing FSS often also alter the circumferential wall stress, another acknowledged molding force of growing collateral vessels. The formation of a collateral circulation after an arterial occlusion correlates well with the calculated increase in FSS because of the increased collateral flow caused by the pressure decrease along pre-existent collaterals. However, because of the fast increase in collateral diameter by cellular proliferation, FSS decreases quickly again, and the early termination of the growth process at an incomplete stage of adaptation is believed to be caused by the only transient action of FSS. One of the hypotheses to be tested was, therefore, whether prolonged action of FSS would also improve the final adaptation by continued growth. The present experiments were therefore undertaken to prospectively study the causal relations between arteriogenesis and FSS by a stepwise and lasting increase of collateral flow brought about by the creation of a side-to-side anastomosis between the distal stump of the occluded femoral artery and its accompanying vei...

The quantitative analysis of protein mixtures is pivotal for the understanding of variations in the proteome of living systems. Therefore, approaches have been recently devised that generally allow the relative quantitative analysis of peptides and proteins. Here we present proof of concept of the new metal-coded affinity tag (MeCAT) technique, which allowed the quantitative determination of peptides and proteins. A macrocyclic metal chelate complex (1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA)) loaded with different lanthanides (metal(III) ions) was the essential part of the tag. The combination of DOTA with an affinity anchor for purification and a reactive group for reaction with amino acids constituted a reagent that allowed quantification of peptides and proteins in an absolute fashion. For the quantitative determination, the tagged peptides and proteins were analyzed using flow injection inductively coupled plasma MS, a technique that allowed detection of metals with high precision and low detection limits. The metal chelate complexes were attached to the cysteine residues, and the course of the labeling reaction was followed using SDS-PAGE and MALDI-TOF MS, ESI MS, and inductively coupled plasma MS. To limit the width in isotopic signal spread and to increase the sensitivity for ESI analysis, we used the monoisotopic lanthanide macrocycle complexes. Peptides tagged with the reagent loaded with different metals coelute in liquid chromatography. In first applications with proteins, the calculated detection limit for bovine serum albumin for example was 110 amol, and we have used MeCAT to analyze proteins of the Sus scrofa eye lens as a model system. These data showed that MeCAT allowed quantification not only of peptides but also of proteins in an absolute fashion at low concentrations and in complex mixtures. Proteomics as a field of research is based on the characterization of an entire proteome of a biological system. A variety of approaches have been developed during the last decades to characterize such mixtures of proteins and peptides, and necessarily, all of them use separation techniques. At the protein level, separation has been achieved using 2-D 1 gel electrophoresis (1) and densitometry of stained proteins or fluorescence detection (2). After digestion of the proteins, peptides were identified using liquid chromatography, mass spectrometry, or both (3, 4). However, this information was only qualitative. It became rapidly evident that quantitative data were definitively required, e.g. for the characterization of dynamic biological systems or the search for biomarkers in clinical proteomics. Subsequently methods have been developed for the quantitative determination of proteins and peptides mainly based on chemical or metabolic isotopic labeling combined with LC/MS n detection (5, 6). Label-free LC/MS quantitative strategies are under development as well (7).Using such techniques, the investigation of changes of the proteome in biological systems has become possible. However, o...

Identification of proteins separated by two-dimensional electrophoresis (2-DE) is a necessary task to overcome the purely descriptive character of 2-DE and a prerequisite to the construction of 2-DE databases in proteome projects. Matrix assisted laser desorption/ionization-mass spectrometry (MALDI-MS) has a sensitivity for peptide detection in the lower fmol range, which should be sufficient for an analysis of even weakly silver-stained protein spots by peptide mass fingerprinting. Unfortunately, proteins are modified by the silver staining procedure, leading to low sequence coverage. Omission of glutaraldehyde increased the sequence coverage, but this improved sequence coverage is still clearly below the sequence coverage starting with Coomassie Brilliant Blue (CBB) R-250-stained spots. Other factors additionally seem to modify proteins during silver staining. By decreasing the protein amount, the advantage of very sensitive detection on the gel is lost during identification, because the resulting low sequence coverage is not sufficient for secure identification. Low-quantity proteins can be identified better starting with CBB G-250 or Zn-imidazol-stained proteins. In contrast, for high-quantity CBB R-250-stained spots, a sequence coverage of up to 90% can be obtained by using only one cleaving enzyme, and up to 80% was reached for medium-quantity spots after combination of tryptic digest with Asp-N- and Glu-C digest.

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