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Biomedical subjects

M Carrier

Publications and source records attributed to M Carrier.

At least 163 records · Page 9Linked to original sources
PubMed1992

Mechanism of hind limb vasoconstriction due to cyclosporin A in the dog.

Cyclosporin A (CSA) causes an acute vasoconstriction of hind limb arterial vessels. To determine the mechanism of action of CSA on the peripheral arterial bed, studies were performed on the isolated femoral artery perfused at constant flow in 61 dogs. Changes in femoral perfusion pressure reflected variations in vascular resistance. Pure powder CSA was dissolved in autologous blood and injected at doses of 1, 5, 10, and 20 mg. Infusions of 1 and 5 mg CSA caused nonsignificant mean increases of 4 +/- 2 mm Hg (95% confidence interval [CI], 0-8; p > 0.05) and 10 +/- 4 mm Hg (95% CI, 0-21; p > 0.05) in femoral perfusion pressure, with CSA blood levels in the femoral vein averaging 40 +/- 16 and 126 +/- 50 nmol/l, respectively, at the end of the injections. Infusions of 10 and 20 mg CSA caused significant increases in femoral perfusion pressure averaging of 8 +/- 3 mm Hg (95% CI, 1-14; p < 0.05) and 20 +/- 4 mm Hg (95% CI, 11-29; p < 0.05) in femoral perfusion pressure. CSA blood levels at the end of injections averaged 271 +/- 99 and 431 +/- 146 nmol/l, respectively, in the femoral vein. Blockade of alpha-adrenergic receptors with phentolamine and surgical lumbar sympathectomy decreased significantly the CSA vasoconstrictive effect in peripheral arterial vessels, with increases in perfusion pressure averaging 29 +/- 5 mm Hg before and 14 +/- 3 mm Hg after phentolamine (p < 0.05) and 30 +/- 2 mm Hg before and 8 +/- 2 mm Hg after sympathectomy (p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenergic alpha-Antagonists↗
PubMed1992

The influence of retrieval on retention.

Four experiments tested the hypothesis that successful retrieval of an item from memory affects retention only because the retrieval provides an additional presentation of the target item. Two methods of learning paired associates were compared. In the pure study trial (pure ST condition) method, both items of a pair were presented simultaneously for study. In the test trial/study trial (TTST condition) method, subjects attempted to retrieve the response term during a period in which only the stimulus term was present (and the response term of the pair was presented after a 5-sec delay). Final retention of target items was tested with cued-recall tests. In Experiment 1, there was a reliable advantage in final testing for nonsense-syllable/number pairs in the TTST condition over pairs in the pure ST condition. In Experiment 2, the same result was obtained with Eskimo/English word pairs. This benefit of the TTST condition was not apparently different for final retrieval after 5 min or after 24 h. Experiments 3 and 4 ruled out two artifactual explanations of the TTST advantage observed in the first two experiments. Because performing a memory retrieval (TTST condition) led to better performance than pure study (pure ST condition), the results reject the hypothesis that a successful retrieval is beneficial only to the extent that it provides another study experience.

Adult↗
PubMed1992

[Salvage heart surgery after percutaneous mitral valvuloplasty].

Percutaneous mitral valvuloplasty (PMV) for selected patients with symptomatic mitral stenosis (MS) has been proposed as a safe alternative to open mitral commissurotomy (OMC) or mitral valvular replacement (MVR). Among 146 consecutive patients undergoing PMV from March 1987 to April 1990, 18 (12%) needed urgent (8) or delayed (10) (average 7 days) corrective surgery following PMV. There were 15 women and 3 men, with a clinical incapacity class II (3) or III (15), and with an intermediate risk for PMV according to echo score (mean = 8). The indications for corrective surgery were: massive mitral regurgitation due to tearing of the anterior leaflet (6), cardiac perforations (left atrium in 2, left ventricle in 3), PMV technical failure (5), severe atrial shunting (2). Operative procedures included MVR (14), cardiac wound suturing only (3), OMC (1). Operative mortality (30 days) was 22% (4/18), equally distributed among the urgent and delayed group. The causes of postoperative death were hemorrhage (2), severe cerebral ischemia (1) and sudden death (1). Compared to operative mortality after OMC (0/17.0%) or MVR (1/32, 3.1%) as the initial treatment for MS during the same time period, cardiac operation after failed or complicated PMV carried a significantly higher mortality (p = 0.004). Therefore, optimal patient selection and aggressive corrective surgery are necessary to decrease the PMV related mortality and morbidity.

Adult↗
PubMed1992

Prevention of herpes simplex virus infection by oral acyclovir after cardiac transplantation.

Infection with herpes simplex virus is common among immunosuppressed patients. In an attempt to prevent such infection, 58 patients (group 1) who underwent cardiac transplantation between 1987 and 1990 were given acyclovir (200 mg orally three times a day) prophylactically throughout their postoperative hospital stay (mean 22 days +/- 1 day). The patients' immunosuppressive protocol included cyclosporine, azathioprine and prednisone. The course of these patients was compared to that of 24 patients (group 2) who underwent cardiac transplantation between 1983 and 1986 but were not given prophylactic antiviral treatment postoperatively. The immunosuppressive protocol in these patients consisted of cyclosporine and prednisone. Herpes infection developed during the 1st year in 5 patients (9%) in group 1 and in 11 patients (46%) in group 2 (p < 0.05). The actuarial rates of freedom from herpes infection at 1, 6 and 12 months after transplantation were 100%, 98% +/- 2% and 95% +/- 3%, respectively, in group 1 and 82% +/- 7%, 58% +/- 11%, 53% +/- 11% in group 2. All viral infections were cutaneous or mucosal, except for one, which developed in a patient with pneumonia. All infections responded well to treatment, although one patient with an infected cornea was left with a permanent visual deficit. The authors conclude that prophylaxis of herpes simplex virus infection with acyclovir administered orally in the early postoperative period is effective in preventing viral infections during the 1st year after cardiac transplantation.

Acyclovir↗
PubMed1992

Mental health, constraints, and organization of work as interactive variables. A study of word processing secretaries.

The effect of a work constraint is specific to the type of work organization. This article deals with the effects of different types of work organization on the mental health of secretaries. The advantage of choosing secretarial work as a research subject lies in the fact that we can identify three distinct types of work organization: (1) a secretary working directly for someone (the "paired" secretary-boss), (2) the "pool," geared toward keyboard input with no specific pairing of secretaries and authors, and (3) the departmental "team," a hybrid of the two preceding types, characterized by the presence of several secretaries, each one assigned to several authors. A study was conducted on the health problems reported by secretaries in the Québec civil service. Data available from a Santé Québec study, carried out at the same time, allowed us to constitute a general population reference group of secretaries and other working women. The findings indicate that secretaries in the general population are no more at risk than are other similar working women, but that secretaries in the provincial civil service are at risk. Regression analysis shows that the same traditional constraints do not affect secretaries in the same way regardless of whether they are members of pair, pool, or team organizations. This suggests that the context of work organization is an interactive or a "specifying variable" of the effect of work constraints on the secretaries' mental health.

Adaptation, Psychological↗
PubMed1992

Cardiac surgery after failed percutaneous mitral valvuloplasty.

Percutaneous mitral valvuloplasty (PMV) has been proposed as a safe alternative to open mitral commissurotomy (OMC) or mitral valvular replacement (MVR) in selected patients with symptomatic mitral stenosis (MS). Among 146 consecutive patients who underwent PMV between March 1987 and April 1990, 18 (12%) needed urgent corrective surgery after the procedure. Of these 18 patients 16 were women and 2 were men. Three patients were of clinical incapacity class II and 15 of class III and were at an intermediate risk for PMV according to the echo score (mean score 8). The indications for corrective surgery were massive mitral regurgitation owing to tearing of the anterior leaflet (six patients), cardiac perforation (left atrium in two patients, left ventricle in three patients), technical failure of PMV (five patients) and severe atrial shunting (two patients). Operative procedures included MVR (14 patients), cardiac wound suturing only (3 patients) and OMC (1 patient). Operative mortality (within 30 days) was 22% (4 of 18 patients), distributed equally among patients needing urgent or elective surgery. When compared with the operative death rate after OMC (0%) and MVR (3.1%) as the initial treatment for MS during the same period, the rate for cardiac operation after failed or complicated PMV (22%) was significantly higher (p = 0.004). Therefore, optimal patient selection and aggressive corrective surgery are necessary to decrease PMV-related morbidity and death.

Adult↗
PubMed1992

Syncope: a symptom of coronary artery spasm after cardiac transplantation.

Two cases of coronary spasm in cardiac transplant recipients in which the presenting symptom was syncope without chest pain are reported. Diagnosing coronary spasm in transplant patients appears to be important because, based upon the few cases in the literature, prognosis is very poor. Coronary spasm may be related to accelerated atherosclerosis occurring in the transplanted heart.

Coronary Artery Disease↗
PubMed1991

The stratification of cardiac surgical procedures according to use of blood products: a retrospective analysis of 1480 cases.

The use of blood products in 1480 consecutive cases of adult cardiac surgical procedures over a period of 15 mth was studied retrospectively using the database of the Department of Anaesthesia of the Institut de Cardiologie de Montréal. Use of blood products was compared in patients having (1) coronary artery bypass grafting, (2) valvular surgery, (3) or a combination of 1 and 2. First operations were compared with reoperations. Overall, the use of homologous blood products was greatest in patients of Group 3, intermediate in patients of Group 2, and smallest in patients of Group 1. Reoperations were associated with an increase in intraoperative transfusion of packed red blood cells, but postoperative chest drainage was similar to first operations. When all blood products (packed red blood cells, fresh frozen plasma and platelets) were taken into consideration, patients undergoing primary CABG or valve surgery were the least exposed to homologous blood donors (five and six units transfused respectively). Repeat CABG was associated with an intermediate exposure to homologous blood products (eight units). Finally, primary and repeat combined procedures, and repeat valve surgery were associated with the greatest exposure to foreign blood products (10, 13 and 10 units respectively). The data presented in this study provide a rational basis for stratification of procedures according to the expected use of blood products, particularly in view of future studies which may be planned to examine the efficiency of blood conservation strategies.

Aged↗
PubMed1991

Dose-dependent effect of cyclosporin on renal arterial resistance in dogs.

Important side effects of cyclosporin (CSA) are renal insufficiency and hypertension. They might be related to a renal vasoconstrictive effect of CSA, and this vascular response might be due to a local mechanism. CSA was injected in isolated renal artery perfused at constant flow in dogs. Changes in renal perfusion pressure reflected variations in vascular resistance. Pure CSA was dissolved in autologous blood and injected at doses of 0.5, 1, 5, and 10 mg. The infusion of 0.5 and 1 mg caused averaged renal perfusion pressure increases of 8 +/- 4 mmHg and 15 +/- 8 mmHg. Renal venous CSA levels averaged 32 +/- 3 and 49 +/- 9 nmol/l, respectively, at the end of injections. Infusion of 5 and 10 mg of CSA caused averaged renal perfusion pressure increases of 32 +/- 12 mmHg and 81 +/- 21 mmHg. Renal venous CSA levels at the end of injections averaged 142 +/- 30 and 382 +/- 82 nmol/l, respectively. A positive correlation was found between the changes in renal perfusion pressure and renal venous CSA levels. Blockade of alpha-adrenergic receptors, surgical renal sympathectomy, administration of thromboxane receptor antagonist, and endothelial-dependent vasodilation by acetylcholine infusion did not affect the renal vasoconstriction effect of CSA; renal response to CSA was prevented by blockade of the Ca channels with diltiazem, and the plasma endothelin concentration in renal venous blood increased significantly after injection of CSA. A dose-dependent increase in renal arterial resistance occurs with therapeutic blood levels of CSA. Renal vasoconstriction is induced by a local effect at the arterial wall, which is independent of neurogenic, adrenergic, and prostaglandin mechanisms.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Effect of direct injection of cyclosporine on the arterial vessels of the isolated hind limb in the dog.

Cyclosporine's toxic side effects are widely recognized as a cause of major morbidity. Peripheral vasoconstriction has been suggested as the pathophysiological mechanism for hypertension and renal failure caused by cyclosporine. To study vascular effects on peripheral arterial circulation, cyclosporine was injected into isolated hind limbs perfused at constant flow in the dog. Pure powder cyclosporine was dissolved in a 10% fat emulsion and infused directly into the arterial inflow of the perfused hind limb (n = 7) at a concentration of 5 mg/kg body weight. Reactivity of the vascular bed was first shown by an average decrease of 72 +/- 4 mmHg (95% confidence interval 63 to 81, P less than 0.01) in hind limb perfusion pressure after infusion of 5 mg nitroglycerin. Infusion of fat emulsion did not cause any significant changes. The infusion of cyclosporine caused an average increase of 29 +/- 5 mmHg (95% confidence interval 17 to 41, P less than 0.01) in hind limb perfusion pressure after 4 mins' infusion. After cyclosporine infusion, the vascular bed still responded to nitroglycerin by an average decrease of 56 +/- 5 mmHg (95% confidence interval 42 to 69, P less than 0.01) in perfusion pressure. Blockade of alpha-receptors with phentolamine in five dogs and ipsilateral lumbar sympathectomy in four prevented the increase in perfusion pressure following cyclosporine injection. In conclusion, cyclosporine injected at high doses causes a small vasoconstriction of the peripheral arterial circulation in the hind limb through stimulation of alpha-adrenergic receptors mediated by the sympathetic nervous system. Since the response is completely abolished by sympathectomy, it is probably caused by reflex activation. A direct effect of cyclosporine on the arterial vessel walls of the limb can therefore be excluded.

Animals↗
PubMed1991

[Effect of therapeutic doses of cyclosporine injected into the renal and femoral arteries in dogs].

Cyclosporine is the core component of all immunosuppressive protocols. Renal insufficiency and hypertension are the two major side effects of cyclosporine use. A vascular effect of cyclosporine could explain these complications. To study the effect of cyclosporine on vessel wall, a model of isolated renal and femoral artery perfusion was used in the dog. The injection of 0.5, 1, 5 and 10 mg of cyclosporine in the renal artery caused an average increase in renal perfusion pressure of 8 +/- 4, 15 +/- 8, 32 +/- 12 and 81 +/- 21 mmHg (p less than 0.05) respectively. Blockade of alpha-adrenergic receptors and renal sympathectomy did not modify the renal vascular response to cyclosporine. The injection of 1, 5, 10 and 20 mg of cyclosporine in the femoral artery caused an average increase in perfusion pressure of 4 +/- 2, 10 +/- 4, 9 +/- 2 and 20 +/- 8 mmHg (p less than 0.05) respectively. Blockade of alpha-adrenergic receptors and lumbar sympathectomy prevented the vasoconstrictive effect of cyclosporine on the femoral artery. Therefore, cyclosporine caused a significant increase in renal perfusion pressure and a modest vasoconstriction of the femoral artery. This effect appears to be related to an adrenergic mechanism only in the femoral circulation. We conclude that other studies are needed to define the mechanism responsible for the vasoconstrictive effect of cyclosporine.

Animals↗
PubMed1991

Noninvasive assessment of cardiac transplant rejection. A critical look at the approach to acute rejection.

The diagnosis of acute rejection remains a key issue in the management of the heart transplant recipient. Myocardial biopsy for tissue examination is the basic step for screening and diagnosis of acute rejection. Although endomyocardial biopsy is reliable, it is an inefficient approach to screening after transplantation and yielded only a 14% rate of positive results in the author's experience, from 1983 to 1990, of 568 biopsies. A reliable noninvasive method for screening acute rejection is therefore needed. Numerous noninvasive methods have been studied to monitor the systemic immune process against the allograft or to evaluate the effect of rejection on graft function and status. For 13 methods of evaluating immune process against the allograft the sensitivity and specificity ranged from 13% to 95% and 19% to 94% respectively. For nine methods of evaluating allograft function, sensitivity and specificity ranged from 60% to 93% and 65% to 97% respectively. Overall, methods monitoring allograft function and status have better results in predicting acute rejection. Nevertheless, the author estimated that 15 episodes of acute rejection would have been missed by these monitoring methods in his group of patients.

Acute Disease↗
PubMed1991

Morbidity and mortality of reoperation for coronary artery bypass grafting: significance of atheromatous vein grafts.

Reoperation ('redo') for coronary artery disease shows a significant increase in morbidity and mortality compared to primary surgery. Some technical approaches have been advocated to decrease myocardial injury, presumably due to coronary artery embolization from atheromatous vein grafts. From 1984 to 1989, 321 'redo' operations were performed at the Montreal Heart Institute. Patients with patent and atherosclerotic vein grafts at preoperative coronary angiography (239 patients) were compared to those with normal or occluded grafts (82 patients). Perioperative myocardial infarction and death rates were 19% and 13%, respectively. They were particularly high among patients with three or more patent and atherosclerotic vein grafts at reoperation (32% and 29%, respectively). Among the 239 patients with patent atherosclerotic grafts, the results of three different surgical techniques were studied retrospectively. A first group of 66 patients had early ligation of patent atheromatous grafts before cardioplegia was administered by antegrade infusion during single aortic clamping for coronary anastomoses, and maintained for the confection of aortic anastomoses. In a second group of 35 patients, early ligation of diseased graft, antegrade cardioplegic delivery, and partial aortic cross clamping for aortic anastomoses of vein grafts was done. In the third group of 138 patients, venous grafts were not interrupted before antegrade cardioplegic infusion and partial aortic cross clamping for aortic anastomoses of vein grafts was used. No significant difference in hospital mortality or perioperative myocardial infarction rate was observed between the three groups of patients. Thus, the modified techniques so far recommended for repeat coronary artery bypass grafting, such as early ligation of patent atherosclerotic grafts, have failed to improve the early results of 'redo' operations.

Adult↗
PubMed1991

[Post-sternotomy mediastinitis: strategy of treatment].

To determine the incidence, the mortality, the risk factors and the most appropriate method for treatment of sternal infections, 9,742 charts were reviewed retrospectively of patients having undergone a sternotomy for cardiac surgery at the Montreal Heart Institute. One hundred and eleven sternal infections (1.1%) were identified: 55 (0.57%) superficial, 56 (0.57%) profound (mediastinitis). The treatment for these profound infections was either debridement, open or closed with drainage irrigation, pectoral flap closure-repair, or epiplooplasty closure. The risk factors for those patients experiencing profound infections were diabetes, obesity, length of the surgical intervention, the time spent in the operating room, and the duration of endotracheal intubation. Eleven of the 111 patients died. The average length of hospitalization were similar for those patients treated by pectoral flap repair and by the epiplooplasty closure. All patients (100%) treated by the epiplooplasty closure developed an epigastric hernia. Six cases of recurrent infection were observed in the group treated by debridement. The average hospital stay was shortened for those patients benefiting from the pectoral flap and epiplooplasty closures. A high incidence of mortality is associated with profound sternal infection. The methods of treatment are various. We recommend as treatment of choice, the pectoral flap closure because there is relatively low risks with this procedure, little to no recurrence of infection, a shorter hospital stay and this procedure does not provoke epigastric hernia.

Adult↗
PubMed1991

[Comparative, clinical and echocardiographic study of the Bex and De Vega annuloplasties].

A retrospective study of 27 cases compared the long term clinical and echocardiographic results of tricuspid valve annuloplasty by the Bex (15 patients) and the De Vega (12 patients) techniques. All patients were in NYHA Classes III or IV before surgery. There was associated mitral valve disease in 24 cases and mixed mitral and aortic valve disease in 3 patients requiring valve replacement. The follow-up period ranged from 3 to 106 months (average 48 +/- 4 months). All patients underwent clinical and color Doppler echocardiographic evaluation. There was symptomatic improvement after surgery as all patients recovered to NYHA Classes I or II. An echocardiographic classification was adopted to assess residual tricuspid regurgitation. The leak was judged to be significant when the surface area of the jet was greater than 5 cm2. Two thirds of patients (17/27) had no significant residual tricuspid regurgitation with the Bex or de Vega techniques of tricuspid annuloplasty according to this criterion. However, significant residual tricuspid regurgitation was observed in 37% of patients (10/27) even though they were all clinically improved. A comparison of the echocardiographic parameters including the severity of residual tricuspid regurgitation, the left and right atrial dimensions, the right ventricular dimensions and tricuspid valve pressure gradients did not show any significant long term difference between the Bex and the De Vega tricuspid annuloplasties.

Echocardiography, Doppler↗
PubMed1991

Accelerated coronary atherosclerosis after cardiac transplantation: major threat to long-term survival.

Accelerated coronary atherosclerosis (ACA) has been documented at autopsy and was noted at coronary angiography in seven patients, 11 to 48 months after cardiac transplantation. To delineate the importance of this problem, the risk factors and the therapeutic approaches in 7 patients who had ACA after heart transplantation were compared with those in 28 patients free of ACA at annual coronary angiography. Ischemic cardiomyopathy was the preoperative diagnosis in all but one patient in the ACA group. The age of the transplant recipients, total myocardial ischemic times and arterial blood pressures at follow-up were similar in both groups. Donor age averaged 31 +/- 3 years in the ACA group and 22 +/- 1 years in patients free of ACA. Preoperative cholesterol, triglyceride and high-density lipoprotein levels were lower in ACA-free patients and the low-density lipoprotein level was higher. At the last follow-up visit, serum lipid levels were similar in both groups. The incidence of acute rejection and of infection was slightly, but not significantly, higher in patients with ACA. The actuarial survival of ACA patients 4 years after transplantation was 30% +/- 20% compared with 100% for patients free of ACA (p less than 0.01). Actuarial rates of freedom from ACA and from death due to ACA were 73% +/- 11% and 81% +/- 11% respectively. Stepwise discriminant analysis showed that older donors and higher pretransplant triglyceride levels were independently related to the development of ACA after cardiac transplantation. In conclusion ACA remains an important cause of late death after heart transplantation. Although therapeutic measures are limited, prevention should focus on strict control of serum lipid levels after transplantation.

Adult↗