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Biomedical subjects

R Dion

Publications and source records attributed to R Dion.

At least 91 records · Page 5Linked to original sources
PubMed1990

A novel preservation medium protecting prostacyclin production and endothelial integrity of the human saphenous vein graft.

Patency rates of coronary artery saphenous vein bypass grafts can be as low as 50% in the first year after surgery. Of these occlusions, 70% can be attributed to mural thrombus formation. Improvements in surgical handling techniques and in preservation media have improved patency rates, as has the introduction of perioperative antiplatelet therapy. The authors describe a novel preservation medium consisting of heparinized blood from the patient, papaverine and dipyridamole. This medium enhances prostacyclin production and maintains endothelial integrity in preserved saphenous vein segments.

Blood Physiological Phenomena↗
PubMed1990

Surgical angioplasty of the left main coronary artery.

The conventional surgical treatment of isolated critical stenosis of the left main coronary artery restores a less physiologic perfusion of the myocardium, leads to occlusion of the left coronary ostium, and consumes an appreciable length of bypass material. Starting in June 1985, 23 surgical angioplasties have been performed in 22 patients. The left main stem was approached posteriorly in the first 11 patients, and an anterior approach was preferred in the last 12 because of better exposure. The onlay patch consisted of saphenous vein in the first 14 patients; pericardium was preferred in the last nine. The five failures occurred early. Four of these occurred in patients older than 60 years in whom calcifications of the left main stem had been seen on the preoperative angiogram. Eighteen procedures (78.3%) succeeded, but one patient (5.5%) died later of a massive air embolism. The 17 survivors are free of symptoms (maximal stress test combined with thallium scintigraphy) after a mean follow-up of 24.3 months. Angiographic restudy at an average of 8 months was obtained in 14 patients (82.3%) and revealed an excellent result in 13. In five patients, a late angiographic restudy (22 to 37 months) still revealed perfect patency of the left main stem. Provided that well-defined contraindications (calcifications, involvement of the distal bifurcation, older age) are respected, surgical angioplasty deserves a place in the array of surgical strategies.

Adult↗
PubMed1989

Sequential mammary grafting. Clinical, functional, and angiographic assessment 6 months postoperatively in 231 consecutive patients.

Between September 1985 and November 1987, 246 sequential mammary grafts were performed in 231 consecutive patients. Seventy-eight percent had triple vessel disease, and 33% required an urgent procedure. The length of the internal mammary artery pedicle was the only limitation to its use. No account was taken of the free cut-end flow of the internal mammary artery. There were 14 bilateral sequential mammary grafts and 15 free sequential mammary grafts. Of the 531 sequential mammary anastomoses, 482 were built with the left internal mammary artery; 113 (21%) were diamond-shaped anastomoses. The right internal mammary artery was brought through the transverse sinus in 44 cases, 10 times for sequential grafting of circumflex branches. Taking into account the adjunctive venous anastomoses and the single internal mammary artery anastomoses, there were 4.5 distal anastomoses per patient, 2.8 being mammary anastomoses and 2.3 being sequential mammary anastomoses. The hospital mortality rate was 2.6%. The prevalence of perioperative myocardial infarction was 5.2%. Follow-up was complete and averaged 15.4 months. Six patients (2.7%) still had angina pectoris. One hundred fifty-seven (71%) patients were recatheterized 6 months after the operation, and 95% of the sequential mammary anastomoses were still patent. The patency rate of the diamond-shaped mammary anastomoses was 94.5% and that of the anastomoses corresponding to the right internal mammary arteries brought through the transverse sinus was 94.3%. The gratifying functional results (maximal stress test combined with exercise thallium scintigraphy) obtained at an average of 6 months postoperatively illustrated the surprising physiologic adaptability of the internal mammary artery. As the attrition rate of the mammary artery grafts beyond 6 months postoperatively is thought to be minimal, gratifying long-term results with widespread use of sequential mammary grafts can be anticipated.

Adult↗
PubMed1989

[Surgical plasty of the left main coronary artery].

Critical stenosis of left main coronary artery (LMCA) is usually treated by conventional bypass surgery. However, this approach consumes an appreciable length of conduit, leads to occlusion of LMCA, and restores only a retrograde perfusion of a rather extensive myocardial area. As from June 1985, we performed 13 LMCA patch plasties in 12 patients. LMCA was approached either posteriorly via a curved aortotomy (9 cases), or anteriorly (4 cases) after retraction, partial or complete division of the main pulmonary artery. In 1 patient, a posterior LMCA plasty failed and a conventional double by-pass graft was needed. This patient underwent, 8 months later, a successful repeat patch plasty using a transpulmonary anterior approach. There was no perioperative myocardial infarction. There was no mortality. All of the patients underwent a 6 months postoperative angiographic control, with an excellent result in 12 cases: a significant restenosis of LMCA was successfully treated by percutaneous coronary angioplasty in 1 asymptomatic patient having concomitantly received a sequential mammary graft. All of the 4 patients are asymptomatic. A direct surgical approach to critical stenosis of LMCA is a valuable alternative treatment for this condition.

Adult↗
PubMed1989

Analysis for alpha-amylase isoenzymes by automated isoelectric focusing.

We describe the fractionation of alpha-amylase (EC 3.2.1.1) isoenzymes by use of the Pharmacia "Phastsystem" electrophoresis apparatus. The separation is done by isoelectric focusing on "Phastgel IEF 5-8." A complete run, including staining, takes 4 h and can easily resolve eight isoenzymes. Samples can be analyzed in a routine laboratory with use of conventional reagents.

Autoanalysis↗
PubMed1988

Modulatory role of the vascular endothelium in the contractility of human isolated internal mammary artery.

1. Endothelium-dependent relaxant responses and modulation of contractile responses were investigated in human isolated internal mammary artery (HIMA), a vessel widely used for coronary bypass surgery. 2. Acetylcholine and ionophore A23187 (both 10 nM-1 microM) elicited concentration-dependent relaxations of precontracted HIMA. These relaxations were abolished after rubbing of the endothelium, they were inhibited by methylene blue and were insensitive to indomethacin. 3. Histamine at concentrations lower than 10 microM elicited an endothelium-dependent, methylene blue-sensitive relaxation of precontracted HIMA. This effect of histamine was inhibited by the H1-receptor antagonist mepyramine. Bradykinin, noradrenaline and alpha 2-adrenoceptor agonists (in the presence of prazosin) did not relax unrubbed HIMA in which acetylcholine or A23187 were shown to be efficient. 4. Tissue levels of guanosine-3':5'-monophosphate (cyclic GMP) were found to be significantly higher in unrubbed HIMA rings than in matched rubbed rings. 5. Methylene blue evoked a slow contraction in resting HIMA, and this contraction was significantly greater in unrubbed than in rubbed preparations. Also, methylene blue enhanced the contractile response of HIMA to noradrenaline and this potentiating effect was significantly greater in unrubbed than in rubbed preparations. Indomethacin induced a slow contraction, of similar magnitude in unrubbed and rubbed HIMA rings. 6. In resting HIMA, the concentration-effect curve of noradrenaline-induced contraction was significantly shifted to the left after rubbing of the endothelium, without change in the maximal responses. In unrubbed rings the EC50 value of noradrenaline was about 2 fold that in rubbed rings. 7. Histamine also contracted resting HIMA in a concentration-dependent manner and in addition, it triggered rhythmic activity. This rhythmic activity was more prominent in unrubbed preparations and could be partially inhibited by indomethacin. The concentration-effect curve of histamine-induced contractions was displaced to the left after rubbing the endothelium, without changes in the maximal responses. The EC50 value of histamine in unrubbed rings was 4 to 9 fold that found in rubbed rings, depending on the level of tension taken into account for the concentration-effect curve during rhythmic contractions. 8. In the presence of nifedipine (3 microM), noradrenaline-induced contractions were not significantly altered, whereas histamine-induced contractions were found to be inhibited by about 70%. 9. It is concluded that in HIMA, both spontaneous and stimulated endothelium-dependent relaxing factor (EDRF) release may occur, and that basal EDRF can itself be responsible for the modulatory effect of endothelium on contractile responses.

Acetylcholine↗
PubMed1988

Should amiodarone be discontinued before cardiac surgery?

Between October 1985 and October 1986, 37 patients, chronically treated with amiodarone, underwent general anesthesia for cardiac, thoracic or vascular surgery. Among them, the 8 non-cardiac surgery patients showed neither intra-, nor postoperative complications. The 29 cardiac surgery patients, had various complications ranging from dysrhythmias (52%), sometimes necessitating a pacemaker (24%), to marked and even fatal vasoplegia. We describe the only fatal case and compare our complication rate with that described in the available literature. Most complications could be symptomatically treated. In addition, amiodarone has a very long elimination half-life: therefore withdrawal before surgery implies delaying operations by several weeks, and puts patients at increased risk of malignant dysrhythmias. However, fatal vasoplegia does occur, and its real incidence should be assessed by a broader survey.

Aged↗
PubMed1985

Right atrial spleen.

A large cardiac tumour occupying most of the right atrium and the right ventricle and causing inflow obstruction to the right heart was confirmed by cross sectional echocardiography in a 41 year old man. After surgical resection histological examination showed that the atrial tumour had the characteristics of splenic tissue. Possible mechanisms for the development of such a tumour include an origin analogous to that of an accessory spleen or the implantation and subsequent growth of lymphoid tissue in a pre-existing superior vena caval or high right atrial angioma.

Adult↗
PubMed1978

Alterations in lysine transfer RNA during erythroid differentiation of the Friend cell.

The proportion of lysine tRNA represented by the isoacceptor species lysine tRNA4 has previously been shown to be largest in cells with the greatest ability to proliferate. Using reverse phase chromatography (RPC-5), we have analyzed the changes in the relative quantities of lysine tRNA species which occur in different cellular states of the Friend cell, a transformed murine cell infected with Friend erythroleukemia virus complex. This cell undergoes erythroid differentiation when exposed to various chemicals. Lysine tRNA4 comprises 32% of the total lysine tRNA in rapidly dividing, uninduced Friend cells, but only 16% of the total lysine tRNA in uninducase. Friend cells undergoing erythroid differentiation divide more slowly than uninduced cells, and finally cease proliferation, but lysine tRNA4 becomes the major lysine tRNA species (greater than 50%). This does not appear to reflect erythroid properties of the cell, since the lysine tRNA of the mouse reticulocyte contains very little lysine tRNA4. The non-dividing erythroid Friend cell, therefore, represents an exception to the finding that non-dividing cells usually have little or no lysine tRNA4 present.

Animals↗
PubMedDate not supplied

Median nerve somatosensory evoked potentials in profound hypothermia for ascending aorta repair.

Median nerve somatosensory evoked potentials (SEPs) were recorded in 9 patients undergoing profound hypothermia for surgical repair of the aortic arch. In addition to the known increase in peak latencies, hypothermia gave rise to the appearance of peaks ('P13,' 'N14') inconsistently recognized at normothermia; moreover, profound hypothermia is associated with the disappearance of cortical activities around 20 degrees, of subcortical waves at lower temperatures. The practical implications of the results are 3-fold: firstly, they suggest that the 'P13' and P14 should both be intracranially generated, at a pre- and postsynaptic level with respect to the cuneate nucleus, respectively; secondly, they show that some discrepancies between previous papers dealing with SEPs and hypothermia can be explained by differences in the choice of the reference; thirdly, they bring some suggestions on a better use of SEPs to monitor patients undergoing aortic arch surgery.

Adult↗