Search PubMed⌕ Search

Biomedical subjects

M Faraggi

Publications and source records attributed to M Faraggi.

89 records · Page 5Linked to original sources
PubMed1972

Electron transfer to ferricytochrome c: reaction with hydrated electrons and conformational transitions involved.

The reaction of horse-heart cytochrome c with hydrated electrons has been studied by the pulseradiolysis technique. In neutral solution, the ferriheme group was reduced in a bimolecular reaction that takes place at a rate equal to that of the decay of the e(-) (aq), and approaches the diffusion-controlled limit. This reduction is assigned mainly to a direct reaction, proceeding via the exposed edge of the porphyrin projecting into the cytochrome c crevice. The reaction absorption spectrum observed 20 musec after an electron pulse was very similar, yet blue-shifted relative to, the difference spectrum between the reduced and oxidized forms of cytochrome c. However, this shift vanishes in a slow monomolecular reaction, which seems to reflect the conformational relaxation of the protein to the final equilibrium state of its reduced form. In alkaline solutions, the transition of cytochrome c molecules into an irreducible conformation causes a proportionate decrease in the amount of ferricytochrome c reduced in the direct reaction. The rate of conformational transition of the protein into the reactive form is now the limiting step for a substantial part of the reduction that takes place via this slow monomolecular reaction. Pseudomonas cytochrome c 551 which, in contrast to horse-heart cytochrome c, is a negatively charged protein at neutral pH reacts with e(-) (aq) at a rate lower than does the horse-heart protein. The reduction of the heme group follows that of the e(-) (aq) decay with a small, yet significant, delay.

Animals↗
PubMedDate not supplied

Residual area at risk after anterior myocardial infarction: are ST segment changes during coronary angioplasty a reliable indicator? A comparison with technetium 99m-labeled sestamibi single-photon emission computed tomography.

BACKGROUND: The aim of this study was to assess whether, after anterior myocardial infarction, ST segment changes during percutaneous transluminal coronary angioplasty (PTCA) of the left anterior descending coronary artery correlated with the amount of ischemic myocardium in the area at risk, measured with 99mTc-labeled sestamibi single-photon emission computed tomography (SPECT) during balloon inflation. METHODS AND RESULTS: Quantitative continuous monitoring of the ST segment was performed during PTCA of the left anterior descending coronary artery in 11 patients, and corresponding SPECT imaging was compared with a rest acquisition performed before PTCA. SPECT was quantified by a bull's-eye analysis according to main criteria: (1) the planimetered defect size during PTCA as an indicator of the size of the area at risk, (2) the change in the pathologic/normal area count ratio in the area at risk as an index of the severity of ischemia, and (3) the difference between the size of the defect during PTCA and at baseline. ST segment changes were correlated to the variation in pathologic/normal area count ratio (19% +/- 14%; r = 0.61; p < 0.05) but not to the sizes of the scintigraphic defects. CONCLUSION: ST segment changes induced by occlusion of the infarct-related coronary artery during PTCA are related mostly to the severity of ischemia rather than to the size of the area at risk.

Adult↗
PubMedDate not supplied

Cardiac gated equilibrium radionuclide angiography and multiharmonic Fourier phase analysis: optimal acquisition parameters in arrhythmogenic right ventricular cardiomyopathy.

BACKGROUND: Multiharmonic Fourier phase analysis of radionuclide angiography is a well-established method for the diagnosis of arrhythmogenic right ventricular cardiomyopathy. We sought to determine the optimal acquisition parameters: number of frames per cycle and number of counts per frame, with all other acquisition and processing parameters being fixed. METHODS AND RESULTS: Radionuclide angiography with list mode acquisition was performed in 10 normal subjects (pilot group) and 11 patients with arrhythmogenic right ventricular cardiomyopathy (validation group), allowing the reconstruction of electrocardiography-gated constant phase studies with different parameters: 16, 24, and 32 frames per cycle and 200, 400, 600, and 800 kcounts per frame. Three harmonics Fourier phase analysis was applied, and optimal acquisition parameters (defined as those providing best homogeneous phase distribution histogram in the pilot group) were defined as judged by the H3 right ventricular phase SD and delta 95%. These were 16 frames per cycle and 600 kcounts per frame. Then we verified in the validation group that these optimal acquisition parameters did not induce any significant relative loss of information compared with other acquisition parameters with more temporal resolution (24 and 32 frames per cycle) or more statistics (800 kcounts per frame). This result was realized by the calculation of normalized H3 right ventricular SD, right ventricular delta 95%, and (SD[left ventricle] - SD[right ventricle]). CONCLUSIONS: In practice, 16 frames per cycle and 600 kcounts per frame are optimal for multiharmonic Fourier phase analysis, with all other acquisition and processing variables being fixed as specified.

Adult↗
PubMedDate not supplied

Optimal 3-dimensional method for right and left ventricular fourier phase analysis in electrocardiography-gated blood-pool SPECT.

BACKGROUND: To overcome some of the limitations imposed by planar imaging, we aimed to optimize the use of first harmonic Fourier phase analysis (FPA) in electrocardiography-gated blood-pool single photon emission computed tomography (GBPS) by comparing different quantitative, 3-dimensional methods. METHODS AND RESULTS: Three groups of patients who underwent GBPS were evaluated: group 1, 8 patients with no heart disease; group 2, 10 patients with left ventricular disease; and group 3, 6 patients with right ventricular disease. Six different methods for FPA were compared: surface, cylindrical, spherical, and hybrid methods with fixed thresholding and spherical and hybrid methods with multiple thresholding. The hybrid method with multiple thresholding for the left ventricle and the spherical method for the right ventricle provided the highest discrimination score (phase) between normal and abnormal ventricles. Among methods with similar discrimination score for these 2 methods, the cylindrical and hybrid methods for the left ventricle and the spherical method for the right ventricle provided the best homogeneity of phase distribution histogram in normal ventricles. These were considered the optimal methods for FPA. CONCLUSIONS: The hybrid or cylindrical method for the left ventricle and the spherical method for the right ventricle with fixed thresholding are the optimal methods for FPA in GBPS.

Electrocardiography↗