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Biomedical subjects

M Yacoub

Publications and source records attributed to M Yacoub.

At least 199 records · Page 11Linked to original sources

Low-dose simvastatin for the treatment of hypercholesterolaemia in recipients of cardiac transplantation.

There is increasing evidence that hypercholesterolaemia is an important contributor to the development of accelerated coronary arterial disease in the cardiac allograft. The optimal drug therapy of hypercholesterolaemia in recipients after cardiac transplantation, however, has not been defined. Simvastatin (an inhibitor of hydroxy-methyl glutaryl-coenzyme A reductase), at a dose of 10 mg/day, was administered to 12 recipients with serum total cholesterol greater than or equal to 7.8 mmol/l and serum triglyceride less than or equal to 4.5 mmol/l refractory to dietary measures during a follow-up period of 1-5 years after cardiac transplantation. All patients received maintenance doses of cyclosporin A and, in some instances, azathioprine and prednisolone. After 2 months treatment with simvastatin, serum total cholesterol was significantly reduced from 8.8 +/- 0.3 mmol/l (mean +/- SEM) to 5.5 +/- 0.5 mmol/l, P less than 0.001, low density cholesterol from 6.6 +/- 0.4 to 3.8 +/- 0.3 mmol/l, P less than 0.001 and triglycerides from 2.4 +/- 0.2 mmol/l to 1.8 +/- 0.2 mmol/l, P less than 0.005. These changes were maintained after a period of treatment of 8 months. Serum high density cholesterol, hepatic transaminase levels, serum creatinine, creatine kinase and cyclosporin A blood levels were not altered by treatment with simvastatin. It is concluded that, in this study group, low-dose simvastatin appears to be well tolerated and has favourable lipid modifying properties.

Adult↗

Immunocytochemical markers of activation in cardiac transplant rejection.

Immunocytochemical analysis of endomyocardial biopsies from cardiac transplant patients has defined changes in expression of antigens, expressed on both the myocardium and endothelium which are characteristic of rejection. Biopsies taken from normal donor heart (prior to transplantation) have been compared with biopsies showing histological signs of rejection. There is induction of MHC class I antigen on the normally negative myocardial plasma membrane and induction of the adhesion molecule ICAM-1 on the intercalating discs. Capillary endothelial cells, which constitutively express Class II DR antigen and ICAM-1 in normal heart show increased of endothelial antigens Pal-E and FVIII-RA during rejection. These results demonstrate perturbation of the endothelial system during rejection and possibly indicate damage to the capillary endothelial cells.

Antigens, CD↗

Coronary reactivity to ergonovine--possible relationship to accelerated coronary arterial disease in cardiac transplant recipients.

Severe coronary artery spasm can occur in orthotopic cardiac transplant recipients. To investigate the possible mechanisms and relevance of coronary spasm to the subsequent development of coronary disease, the response of the coronary arteries to intracoronary ergonovine maleate was studied in 10 patients who had undergone orthotopic cardiac transplantation and were shown to have normal coronary arteries at angiography. Ergonovine in doses of 1, 5 and 10 micrograms was injected into the left coronary artery followed by 2 mg of isosorbide dinitrate. Proximal coronary artery luminal diameters were measured using automated computerized quantitative angiography of the left anterior descending (LAD) and circumflex (LCX) vessels. Five patients (responders) demonstrated a dose response curve to intracoronary ergonovine which was similar to that previously seen in non-transplant patients (mean percentage diameter change +/- SEM, -24.68 +/- 1.93 for LAD, -24.06 +/- 3.91 for LCX). The remaining five patients (non-responders) demonstrated a virtually flat dose response curve significantly different from that of the responders (P = 0.001 for LAD, P = 0.013 for LCX). Angiography after 2 years demonstrated significant coronary disease in four of the five responders to ergonovine. In contrast, the five non-responders to ergonovine continue to have no detectable disease by angiography.

Adult↗

Response of recurrent giant cell myocarditis in a transplanted heart to intensive immunosuppression.

A 35-year-old man developed giant cell myocarditis resulting in severe congestive cardiac failure. He needed urgent orthotopic cardiac transplantation despite maximal doses of inotropes and augmentation with an intra-aortic balloon pump. The patient presented with rhythm disturbances and echocardiographically diminished ventricular function at subsequent follow-up. Biopsies then taken revealed recurrence of myocarditis in the transplanted heart. Investigations revealed no obvious cause for the myocardial granulomas nor any evidence of systemic granulomatous disease. The patient received, in addition to maintenance cyclosporin A and azathioprine, high doses of corticosteroids which resulted in complete resolution of the inflammatory process and no recurrence has been detected to date. This case shows that giant cell myocarditis can recur in the transplanted heart despite routine immunosuppression with azathioprine and cyclosporin A and that additional treatment with high dose corticosteroids is effective in causing regression of the inflammatory process.

Adult↗

Surgical treatment of coronary artery anomalies.

In this paper, we review literature from June 1990 through May 1991. We discuss normal anatomy and physiology of the proximal coronary arteries, anomalous origin of the coronary arteries from an inappropriate aortic sinus, and anomalous origin of the left coronary artery from the pulmonary artery. Other topics reviewed include coronary arteriovenous fistulas, coronary anomalies in left-sided heart syndrome and pulmonary atresia with intact interventricular septum, coronary arterial abnormalities in transposition of the great arteries, and iatrogenic coronary anomalies.

Arteriovenous Fistula↗

Expression of ABH blood group antigens in human heart tissue and its relevance to cardiac transplantation.

Blood group antigen expression was assessed in cardiac tissue taken during heart transplantation. The samples were from ten donors and nine recipients, of whom seven were blood group A, three were group B, two were group AB, and seven were group O. Cryostat sections were studied by immunofluorescence microscopy. Blood group antigens were confined to the mesothelial cells on the surface of the epicardium and the cardiovascular endothelium where they were consistently demonstrated according to erythrocyte blood group using a rabbit anti-A serum, monoclonal antibodies against A and B antigens, and the H antigen-specific lectin Ulex europaeus. The cardiac muscle itself was negative for blood group antigen. The results indicate that there is some variation in antigen expression between individuals, which may explain why transplants have occasionally been successful in breaching the blood group ABO barrier.

ABO Blood-Group System↗

Lung mast cells in plexogenic pulmonary arteriopathy.

The numbers of mast cells/mm2 of lung parenchyma were counted in four controls, 15 cases of primary plexogenic pulmonary arteriopathy (PPA), and 17 cases in which the arteriopathy was secondary to congenital heart disease, to determine if increased numbers occur in PPA and with what stage of disease they might be associated. Considerable accumulations of lung mast cells may occur in this disease, but these are not closely related to any particular histological stage in the development of the arteriopathy. It is postulated that while mast cells could conceivably exert a vasodilatory effect on constricted small pulmonary arteries, it seems more likely that they are part of the parenchymal changes that commonly develop in this disease.

Adolescent↗

Responses of atherosclerotic human coronary arteries in vivo to the endothelium-dependent vasodilator substance P.

BACKGROUND: The effects of the endothelium-dependent vasodilator substance P (SP) on atherosclerotic human coronary arteries was studied. METHODS AND RESULTS: [125I]-SP binding to luminal cells was shown to be preserved in the atherosclerotic epicardial coronary arteries of four patients. No binding to medial smooth muscle cells was demonstrated. Intracoronary infusions of SP were undertaken in patients with coronary artery disease. SP was infused for 2-minute periods starting at a dose of 2.8 pmol/min rising by doubling increments to 22.4 pmol/min. Analysis of the epicardial coronary artery diameter, using a computerized analysis system (CAAS) of the angiograms, was performed at the end of each infusion. Analysis of seven smooth vessel segments from seven coronary vessels, which were stenosed at more proximal sites, was performed. Significant dose-dependent dilatation was seen (p = 0.04), which was maximal at 5.6 pmol/min SP. No additional dilatation was produced with 2 mg intracoronary isosorbide dinitrate (ISDN). Two of these seven patients showed no response to SP, and only one of these appeared to sustain dilatation with ISDN (2 mg intracoronary). In a second group of six patients with discrete coronary stenoses, analysis at the site of the stenosed segments appeared to reveal dilatation in response to SP in only one instance. One other stenotic segment dilated with isosorbide dinitrate but failed to dilate with SP; the remaining four were fixed. The segment immediately proximal to the stenosis preserved a dose-dependent vasodilator response. CONCLUSIONS: These findings demonstrate that the endothelium-dependent vasodilator substance P can still produce epicardial vasodilatation in vivo in the presence of coronary atherosclerosis.

Autoradiography↗

[Myasthenia in children. Apropos of 3 cases].

We report 3 cases of juvenile myasthenia in 2 girls and 1 boy, who at onset, were respectively 21 months, 13 yr and 4 and a half yr old. Clinical features were common but in 2 cases included acute respiratory failure leading to artificial ventilation. Thymectomy was performed in 1 girl with thymoma who presented a vitiligo 5 yr later.

Adolescent↗

[Cardiac involvement in mucopolysaccharidosis. Apropos of an echocardiographic study in 8 cases].

Of all the storage diseases, mucopolysaccharidosis is the one whose cardiac manifestations are probably the least well known. Clinical and above all echocardiographic findings of heart involvement were studied in 8 patients with mucopolysaccharidosis, including four with Hunter disease. The paucity of clinical manifestations was in sharp contrast with the highly informative echocardiographic results. Valvular dystrophy, usually of the left side of the heart, was the most common anomaly, with five patients affected. Whereas some valvular lesions had no consequences, others led to stenosis or incompetence. Asymmetrical hypertrophy of the septum was found in one patient. No patient had evidence suggestive of vascular involvement, in particular of the coronary arteries.

Adolescent↗

Aortic counterpulsation for up to 28 days with autologous latissimus dorsi in sheep.

This article reports the development and assessment of an entirely autologous extraaortic counterpulsation system using skeletal muscle (latissimus dorsi). The technique has been performed and assessed in 16 sheep to quantify the effectiveness of counterpulsation over periods up to 28 days and to optimize the stimulation regimens for muscle contraction and fiber-type transformation. Hemodynamic changes have been quantified by calculation of the endocardial viability ratio. This has shown an increase of between 12% and 89% for 28 days. The wide variety of increase observed has been related to the development of an optimum flap configuration. The technique of surface impedance monitoring of flap blood flow has allowed the start of electrical stimulation after 48 hours with the introduction of hemodynamic benefit (1:4 mode) during the process of fiber-type transformation (in situ training). Extraaortic counterpulsation with autologous latissimus dorsi has been shown to be effective and safe for as long as 28 days. It has not been associated with any thromboembolic or infective complications, which we attribute to the exclusion of any foreign material in the design.

Animals↗

Ciliary beat frequency and structure of recipient and donor epithelia following lung transplantation.

To investigate possible changes following lung transplantation, the structure and in vitro ciliary beat frequency (CBF) of airway epithelium from the cytology brushings of 9 heart-lung (HLT) and 5 single-lung (SLT) transplant recipients were examined. The CBF of brushings taken proximal and distal to the anastomosis was measured 2-10 months following transplant. There was no difference between the measured mean CBF at the two sites or between the two groups; HLT CBF: distal 11.0 +/- 0.5 Hz (standard error of mean), proximal 10.5 +/- 0.4 Hz, SLT CBF: distal 11.7 +/- 0.9 Hz, proximal 12.0 +/- 0.6 Hz. Mean CBF of bronchial brushings (except distal brushings from SLT patients) was significantly lower than that from controls: 13.6 +/- 0.3 Hz (n = 7) (p less than 0.05). Transmission electron microscopy of epithelial brushings from 4 patients (3 HLT, 1 SLT) revealed epithelial abnormalities both proximal and distal to the anastomosis, particularly ciliary depletion, mitochondrial abnormalities and death of cells. No significant ciliary ultrastructural abnormalities were seen in any tissue. We conclude that epithelial abnormalities were observed both proximal and distal to the anastomosis following lung transplantation. These may contribute to impairment of mucociliary clearance.

Bronchi↗