Alper Uzun | PubMed Health

PubMed2006

Correlation of modified allen test with Doppler ultrasonography.

The feasibility of using modified Allen tests to evaluate arterial circulation in the forearm for possible radial artery grafting, and the correlation of these tests with Doppler ultrasonography, were examined. The hand circulation of 50 patients scheduled for coronary artery bypass grafting was assessed by plethysmography, pulse oximetry, and pencil Doppler, as well as Doppler ultrasonography. Flow, velocity, and diameter of the radial, ulnar, and snuffbox arteries were recorded, and radiological screening indices were evaluated to establish a standard set of criteria. The results of modified Allen tests by plethysmography and pulse oximetry demonstrated the dominance of the ulnar artery. The indices of flow x diameter and velocity x diameter, obtained from Doppler ultrasound measurements, confirmed the dominance of the ulnar artery. When compression was applied to the arteries sequentially, significant alterations were found. The arterial circulation in the forearm can be safely evaluated by the modified Allen tests with plethysmography, pulse oximetry, and pencil Doppler, as these results correlated with Doppler ultrasound.

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PubMed2005

Active site prediction for comparative model structures with thematics.

THEMATICS (Theoretical Microscopic Titration Curves) is a simple, reliable computational predictor of the active sites of enzymes from structure. Our method, based on well-established Finite Difference Poisson-Boltzmann techniques, identifies the ionisable residues with anomalous predicted titration behavior. A cluster of two or more such perturbed residues is a very reliable predictor of the active site. The protein does not have to bear any resemblance in sequence or structure to any previously characterized protein, but the method does require the three-dimensional structure. We now present evidence that THEMATICS can also locate the active site in structures built by comparative modeling from similar structures. Results are given for a total of 21 sets of proteins, including 21 templates and 83 comparative model structures. Detailed results are presented for three sets of orthologous proteins (Triosephosphate isomerase, 6-Hydroxymethyl-7,8-dihydropterin pyrophosphokinase, and Aspartate aminotransferase) and for one set of human homologues of Aldose reductase with different functions. THEMATICS correctly locates the active site in the model structures. This suggests that the method can be applicable to a much larger set of proteins for which an experimentally determined structure is unavailable. With a few exceptions, the predicted active sites in the comparative model structures are similar to that of the corresponding template structure.

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