Biomedical subjects
Publications and source records attributed to R Melamed.
We describe the first pregnancy in a homozygous familial hypercholesterolemic woman who started plasma exchange therapy 3 years before she became pregnant. We especially studied the effects of plasma exchange on lipid profile, uteroplacental circulation, and pregnancy course.
An improved method for the analysis of doxycycline hyclate by high-performance liquid chromatography using polystyrene-divinylbenzene column packings is described. The separation obtained with this method was compared with that of other, recently described methods. The improved method was examined in a collaborative study involving five separate laboratories, using 11 different columns and four discrete samples. The main component and impurities were determined. An analysis of variance showed absence of consistent laboratory bias and presence of significant laboratory-sample interaction. Estimates for the repeatability and reproducibility of the method, expressed as relative standard deviations (RSD) of the result of the determination of doxycycline, were found to be 0.9 and 1.2%, respectively.
Endothelium provides a specific binding site for Factor IX/IXa which can propagate activation of coagulation by promoting Factor IXa-VIII-mediated activation of Factor X. In this report the endothelial cell Factor IX/IXa binding site has been identified and the coagulant function of the receptor blocked. Studies using [3H]Factor IX derivatized with the photoaffinity labeling agent N-succinimidyl-6-(4'-azido-2'-nitrophenylamino)hexanoate (SANPAH) and cultured bovine endothelial cells demonstrated cross-linking to a trypsin-sensitive cell surface protein of Mr approximately equal to 140,000. Immunoprecipitation of metabolically labeled endothelium with Factor IX derivatized with the cleavable cross-linking agent N-succinimidyl(4-azidophenyl)-1,3'-dithiopropionate and antibody to Factor IX demonstrated the endothelial cell origin of the Mr 140,000 cell surface protein. Blockade of the Factor IX/IXa binding protein by covalently linking SANPAH-5-dimethylaminonaphthalene-1-sulfonyl-Glu-Gly-Arg-Factor IXa or SANPAH-Factor IX prevented both specific Factor IXa binding and effective Factor IXa-VIII-mediated activation of Factor X on endothelium. Following extraction of endothelium with detergents, Factor IX/IXa binding activity was solubilized and could be assayed using a polyvinyl chloride plate binding assay. Western blots of cell extracts demonstrated binding of 125I-Factor IX at Mr approximately equal to 140,000 which was blocked by excess Factor IX, but not antisera to Factor VIII, von Willebrand factor, alpha 2-macroglobulin, or epidermal growth factor receptor. These data indicate that endothelium provides a distinct binding site for Factor IX/IXa consisting, at least in part, of a membrane protein which can modulate the coagulant activity of Factor IXa on the cell surface.
The incidence and the clinical significance of various forms of anomalous aortic origin of coronary arteries are not well known. Among 2,000 consecutive patients who underwent selective coronary aretriography, 11 had such anomalies (0.55%). Two patients with atresia of the left main ostia developed ischemic symptoms at the ages of thirty-five and fifty-two, and both benefitted from coronary bypass graft operation. In other forms of anomalies the presence of ischemic symptoms was also associated with atherosclerotic stenosis (7 patients) or with constricting muscle bridge (1 patient).
Concealed pentageminy was observed during 10 h of Holter monitoring in a 27-year-old woman without apparent heart disease. In a continuous electrocardiographic recording the number of sinus beats within 114 consecutive interectopic intervals complied with the formula of S = 5n-1. The probability of this occurring by chance alone is infinitesimally small (p = 2(-114).
One reason for failure of nerve recovery after suture or nerve grafting is the inappropriate matching of motor and sensory fibers. Methods used in attempting to solve this problem have either been unprecise, too time consuming, or unpleasant to the patient. Both experimentally and on cadaver samples, the level of choline acetylase activity is eight times higher in motor nerve fascicles than in sensory fascicles. In experimentally cut nerves, the ChAC activity remained high even after a period of 45 days. Thus it was possible to identify both ends of the motor and sensory fascicles in fresh injuries, and the proximal parts in old injuries. We have since used this method of intraoperative nerve identification in three patients. It has proved to be a rapid (70-80 minutes), viable technique for the immediate differentiation between proximal parts of motor and sensory nerve fascicles in cases of old nerve injuries. In contrast to our animal studies we found that the ChAC activity in the distal segment was still different for the various fascicles five months after transection. Presumably the present need for distal exploration to identify the "target organ" can be avoided.
Choline acetyltransferase (ChAC) measurement after complete transection of the sciatic nerve in rats revealed a steady increase in ChAC in the proximal nerve stump and a rapid drop in ChAC in the distal nerve stump. Ninety-six hours following transection no appreciable ChAC activity could be detected in the distal segment. The increase in the proximal segments was followed by a slight decline and leveling off at about twice the normal level. End-to-end nerve anastomosis, using the enzymatic nerve differentiation technique, could therefore be performed up to the first 96 hours. Nerve grafts could be used, with markedly improved results, up to the forty-fifth day following transection.
A rapid and precise nerve fascicle identification method based on the enzymatic activity of choline acetyltransferase (choline acetylase, or ChAC) is described. Motor nerve facicles demonstrated significantly higher ChAC activity in comparison to sensory nerve facicles. Based on this difference in activity, matching of nerve fascicle cut ends is possible in cases of recent trauma.
The transit time of contrast material through a proximal segment of right coronary and anterior descending arteries were measured from cineangiograms by means of a projector-linked frame counter. The time required for the contrast material to traverse a 15-cm segment from the ostia was more than 800 msec in 58 out of 80 vessels with more than 85% stenosis and only in 12 of 129 vessels with up to 85% stenosis. This simple measurement during routine interpretation of cineangiograms may add valuable information.
The clinical and pathological features in three cases of false aneurysm of the left ventricle are reported. In two instances the condition developed after myocardial infarction, and in the third case a mycotic pseudoaneurysm developed after purulent pericarditis. All three patients were in intractable heart failure before urgent operation. The correct diagnosis was established preoperatively by angiography. In all three cases the aneurysms were successfully resected and the left ventricle reconstructed. An aggressive surgical approach is warranted in the management of this lesion.
Acute bacterial endocarditis developed in a 65-year-old man two years after surgical resection of a false aneurysm of the left ventricle. The patient had cerebral embolic manifestations, and coagulase-positive Staphylococcus aureus was cultured from each of six blood samples. A pericardial friction rub and a changing pansystolic murmur appeared during the third week of hospitalization. The presence of a false aneurysm was once again demonstrated on ventriculographic studies. This was successfully repaired, employing cardiopulmonary bypass. The sequence of events in this patient suggests that bacterial endocarditis at the site of a previous cardiomyotomy might have led to the development of the second pseudo-aneurysm.
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A further case of osteogenesis imperfecta with valvular heart disease is added to the 12 already reported in the literature. The presence of a dilated mitral annulus and a ballooned mitral leaflet in this case together with the findings reported in the literature leave little doubt as to the relationship between the valvular lesion and the underlying connective tissue disorder.
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