Precise higher-order reflectivity and morphology models for early diagnosis of diabetic retinopathy using OCT images.

This study proposes a novel computer assisted diagnostic (CAD) system for early diagnosis of diabetic retinopathy (DR) using optical coherence tomography (OCT) B-scans. The CAD system is based on fusing novel OCT markers that describe both the morphology/anatomy and the reflectivity of retinal layers to improve DR diagnosis. This system separates retinal layers automatically using a segmentation approach based on an adaptive appearance and their prior shape information. High-order morphological and novel reflectivity markers are extracted from individual segmented layers. Namely, the morphological markers are layer thickness and tortuosity while the reflectivity markers are the 1st-order reflectivity of the layer in addition to local and global high-order reflectivity based on Markov-Gibbs random field (MGRF) and gray-level co-occurrence matrix (GLCM), respectively. The extracted image-derived markers are represented using cumulative distribution function (CDF) descriptors. The constructed CDFs are then described using their statistical measures, i.e., the 10th through 90th percentiles with a 10% increment. For individual layer classification, each extracted descriptor of a given layer is fed to a support vector machine (SVM) classifier with a linear kernel. The results of the four classifiers are then fused using a backpropagation neural network (BNN) to diagnose each retinal layer. For global subject diagnosis, classification outputs (probabilities) of the twelve layers are fused using another BNN to make the final diagnosis of the B-scan. This system is validated and tested on 130 patients, with two scans for both eyes (i.e. 260 OCT images), with a balanced number of normal and DR subjects using different validation metrics: 2-folds, 4-folds, 10-folds, and leave-one-subject-out (LOSO) cross-validation approaches. The performance of the proposed system was evaluated using sensitivity, specificity, F1-score, and accuracy metrics. The system's performance after the fusion of these different markers showed better performance compared with individual markers and other machine learning fusion methods. Namely, it achieved [Formula: see text], [Formula: see text], [Formula: see text], and [Formula: see text], respectively, using the LOSO cross-validation technique. The reported results, based on the integration of morphology and reflectivity markers and by using state-of-the-art machine learning classifications, demonstrate the ability of the proposed system to diagnose the DR early.

Case report: off-pump total myocardial revascularization for dextrocardia and situs inversus.

A 42-year-old man with dextrocardia and situs inversus underwent successful off-pump total myocardial revascularization using the technique popularized by Tector [Tector 1994, Tector 1996]. The free left internal mammary artery (LIMA) was anastomosed to the in-situ right internal mammary artery (RIMA) at the level of the right-sided left atrial appendage, then anastomosed sequentially to the first diagonal branch (D1) of the left anterior descending artery (LAD), and to the LAD. The in-situ RIMA was sequentially anastomosed to the first and the second obtuse marginal branches (OM1 and OM2) of the circumflex coronary artery. A saphenous vein was then anastomosed to a diffusely diseased posterior descending branch (PDA) of the right coronary artery (RCA). The patient was asymptomatic and in excellent condition three months after surgery. In economically depressed regions of the world, such as the Gaza Strip, off-pump complete revascularization is an excellent alternative to cardiopulmonary bypass.

Effects of nisoldipine upon endothelial dysfunction following ischaemic and peroxidative injury in the perfused rat heart.

OBJECTIVE: Previous studies showed that treatment of hearts with nisoldipine improves recovery of cardiac function following ischaemia, improves reperfusion, and reduces the constrictor sensitivity to endothelin. The aim of the present study was to assess the reduction in vasodilator responses that occurs following ischaemia and reperfusion or after oxidative stress, and to determine whether nisoldipine treatment improves these dilator responses. METHODS: Isolated perfused rat hearts were studied. Coronary vessels were constricted by the addition of U46619 and dilator responses were determined with the addition of acetylcholine (endothelium dependent) or glyceryl trinitrate (endothelium independent). Responses were compared before and after low flow ischaemia (20%, 30 min) and reperfusion (30 min), or treatment with tert-butyl hydroperoxide (tBHP) (0.9 mM, 12 min, 30 min wash). RESULTS: The addition of U46619 caused a prolonged increase in perfusion pressure of 50 to 70 mm Hg which was not significantly different before and after treatment. Dilatation responses to acetylcholine were significantly reduced following ischaemia and reperfusion (34% of preischaemic values) or tBHP (47.6% of pre-tBHP values), while responses to glyceryl trinitrate were not significantly changed. In contrast, when hearts were perfused with nisoldipine, the responses to acetylcholine were significantly improved (88% of preischaemic values with 5 nM nisoldipine, and 68% to 78% of pre-tBHP values with 0.5 nM to 5 nM nisoldipine). Responses to acetylcholine following tBHP were not significantly improved when hearts were perfused with verapamil (5 nM 43.5%, 5 microM 32%, of pre-tBHP values), or diltiazem (5 nM 37%, 5 microM 31%, of pre-tBHP values). CONCLUSIONS: Ischaemia and reperfusion or oxidative stress reduced endothelium dependent responses, but not endothelium independent responses. Nisoldipine reduced the injury to endothelial cell function associated with ischaemia and reperfusion or oxidative stress.

Porphyrin Biosynthesis in Cell-free Homogenates from Higher Plants.

The porphyrin and phorbin biosynthetic activity of etiolated cucumber (Cucumis sativus, L.) cotyledons was compared to that of cotyledonary homogenates. Etiolated cotyledons incubated with delta-aminolevulinic acid accumulate protoporphyrin, coproporphyrin, small amounts of Mg protoporphyrin monoester, and trace amounts of uroporphyrin. They also incorporate 4-(14)C-delta-aminolevulinic acid into free porphyrins, protochlorophyllide, protochlorophyllide phytyl ester, and Mg protoporphyrin monoester. Homogenates incubated with delta-aminolevulinic acid likewise accumulate coproporphyrin, uroporphyrin, Mg coproporphyrin, and trace amounts of protoporphyrin. They also incorporate 4-(14)C-delta-aminolevulinic acid into Mg protoporphyrin monoester, Mg coproporphyrin, and free porphyrins. However, the capacity to synthesize protochlorophyllide and protochlorophyllide phytyl ester is lost and the endogenous protochlorophylls gradually disappear. Mg protoporphyrin monoester represents the terminal biosynthetic step in this cell-free system.

Photochlorophyll Biosynthesis in Cucumber (Cucumis sativus, L.) Cotyledons.

The formation of protochlorophyllide and protochlorophyllide phytyl ester was investigated during etioplast biogenesis in order to study the biosynthetic relation of these two compounds. Protochlorophyllide accumulates slowly during the first 2 days of germination, its rate of formation increases sharply during the 3rd day, and then it decreases. Protochlorophyllide phytyl ester starts accumulating a day later; its formation coincides with the initiation of xanthophyll biosynthesis. Kinetic analysis of specific radioactivities after (14)C labeling of the protochlorophyll pools does not support the currently accepted conversion of protochlorophyllide into protochlorophyllide phytyl ester, but suggests that both compounds originate simultaneously from a common precursor pool.