A comparison of failure modes of glutaraldehyde-treated versus antibiotic-preserved mitral valve allografts implanted in sheep

Morphologic studies and calcium analyses were made on mitral valve allografts from 12 juvenile sheep surviving 12 to 24 weeks after mitral valve replacement. Before implantation, the allografts were treated with 0.625% glutaraldehyde (group I, n=4) or with cold antibiotic solution (group II, n=8). Three group I animals died 12 to 19 weeks after implantation because of dysfunction of calcified valves; the surviving animal also had extensive allograft calcification. One group II animal died of mitral regurgitation; the valves of the other seven (including five with regurgitation shown by Doppler and ventriculographic studies) were explanted at 19 to 24 weeks. Chordal rupture related to calcific deposits was found in all group I valves. Leaflet perforations (n=4) and ruptured chordae (n=4), each caused by connective tissue deterioration, were found in group II valves. Inflammatory reaction was absent or minimal in group I valves but moderate or severe in group II valves. Fibrous sheaths were thicker in group II than in group I valves. Calcium levels were much higher in group I than in group II valves. Calcification in group I valves was diffuse and involved collagen, elastic fibers, and connective tissue cells and matrix; in group II valves, it was localized in connective tissue cells. Thus glutaraldehyde-treated allografts failed because of extensive calcification, whereas antibiotic-preserved allografts underwent deterioration of connective tissue and infiltration by inflammatory cells

Restrictive Cardiomyopathy, Atrioventricular Block and Mild to Subclinical Myopathy in Patients With Desmin-Immunoreactive Material Deposits

AbstractObjectives. We present clinical data and heart and skeletal muscle biopsy findings from a series of patients with ultrastructural accumulations of granulofilamentous material identified as desmin.Background. Desmin cardiomyopathy is a poorly understood disease characterized by abnormal desmin deposits in cardiac and skeletal muscle.Methods. Clinical evaluation, endomyocardial and skeletal muscle biopsy, light and electron microscopy and immunohistochemistry were used to establish the presence of desmin cardiomyopathy.Results. Six hundred thirty-one patients with primary cardiomyopathy underwent endomyocardial biopsy (EMB). Ultrastructural accumulations of granulofilamentous material were found in 5 of 12 biopsy samples from patients with idiopathic restrictive cardiomyopathy and demonstrated specific immunoreactivity with anti-desmin antibodies by immunoelectron microscopy. Immunohistochemical findings on light microscopy were nonspecific because of a diffuse intracellular distribution of desmin. All five patients had atrioventricular (AV) block and mild or subclinical myopathy. Granulofilamentous material was present in skeletal muscle biopsy samples in all five patients, and unlike the heart biopsy samples, light microscopic immunohistochemical analysis demonstrated characteristic subsarcolemmal desmin deposits. Two patients were first-degree relatives (mother and son); another son with first-degree AV block but without myopathy or cardiomyopathy demonstrated similar light and ultrastructural findings in skeletal muscle. Electrophoretic studies demonstrated two isoforms of desmin—one of normal and another of lower molecular weight—in cardiac and skeletal muscle of the familial cases.Conclusions. Desmin cardiomyopathy must be considered in the differential diagnosis of restrictive cardiomyopathy, especially in patients with AV block and myopathy. Diagnosis depends on ultrastructural examination of EMB samples or light microscopic immunohistochemical studies of skeletal muscle biopsy samples. Familial desminopathy may manifest as subclinical disease and may be associated with abnormal isoforms of desmin

Comparison of the severity of the chronic cardiotoxicity produced by doxorubicin in normotensive and hypertensive rats

A comparison was made of the severity of chronic doxorubicin cardiotoxicity in adult male spontaneously hypertensive rats (SHR) and in genetically related normotensive Wistar-Kyoto rats (WKY). Groups of SHR and WKY were given 12 weekly iv injections of doxorubicin at 0.25, 0.5, or 1.0 mg/kg. When the study was concluded, mean arterial pressure was 127 to 161 nm Hg in doxorubicin-treated SHR compared with 74 to 87 mm Hg in similarly treated WKY. Lesions, consisting mainly of cytoplasmic vacuolization and myofibrillar loss, were noted in the hearts from both types of rats given the 1.0-mg/kg dose and were considerably more severe in SHR than in WKY (average scores 3.8 and 2.0). Renal lesions (glomerular vacuolization and dilatation of tubules with accumulations of proteinaceous material) were of comparable severity in both types of rats at the 9- and 12-mg/kg cumulative doses; however, they were more severe in SHR at the 6-mg/kg cumulative dose. Moderate cardiac alterations were present in all SHR (average score 1.6) given 0.5 mg doxorubicin/kg; at the same dose, lesions were minimal in two and absent in three WKY. In a second study, groups of rats were killed 1 week after 3, 6, 9, or 12 weekly iv injections of doxorubicin (1.0 mg/kg). Myocardial lesions were noted initially in SHR after six doses and in WKY after nine doses. Three of five SHR were dead by the 12th dose. These results indicate that spontaneously hypertensive rats are much more sensitive than normotensive rats to the cardiotoxic effects of doxorubicin

Morphological aspects of the myocarditis and myositis in Calomys callosus experimentally infected with Trypanosoma cruzi: fibrogenesis and spontaneous regression of fibrosis

Calomys callosus a wild rodent, is a natural host of Trypanosoma cruzi. Twelve C. callosus were infected with 10(5) trypomastigotes of the F strain (a myotropic strain) of T. cruzi. Parasitemia decreased on the 21 st day becoming negative around the 40th day of infection. All animals survived but had positive parasitological tests, until the end of the experiment. The infected animals developed severe inflammation in the myocardium and skeletal muscle. This process was pronounced from the 26 th to the 30th day and gradually subsided from the 50 th day becoming absent or residual on the 64 th day after infection. Collagen was identified by the picro Sirius red method. Fibrogenesis developed early, but regression of fibrosis occurred between the 50th and 64th day. Ultrastructural study disclosed a predominance of macrophages and fibroblasts in the inflammatory infiltrates, with small numbers of lymphocytes. Macrophages had active phagocytosis and showed points of contact with altered muscle cells. Different degrees of matrix expansion were present, with granular and fibrilar deposits and collagen bundles. These alterations subsided by the 64th days. Macrophages seem to be the main immune effector cell in the C. callosus model of infection with T. cruzi. The mechanisms involved in the rapid fibrogenesis and its regression deserve further investigation