Vergleichende histochemische, fluorescenzmikroskopische und elektronenoptische Untersuchungen zur Fr�hdiagnose des Herzinfarktes der Ratte

Fluorescence microscopy in the detection of early myocardial infarction

Fluorescent microscopy is amongst the many techniques devised for the post-mortem detection of early myocardial infarction. The method has the advantage of sensitivity, speed and simplicity, compared with more complex techniques such as enzyme histochemistry and electron microscopy. Disadvantages include the difficulty of permanent preservation of the sections and lack of sharp differentiation between normal and very early infarction--though the latter problem is common to most other methods, except enzyme histochemistry. There are two main techniques in fluorescent microscopy: The examination of sections specifically stained by fluorochrome dyes; The re-examination of haematoxylin-eosin sections for 'autofluorescence'.

An autofluorescence method for the diagnosis of early ischaemic myocardial lesions. A systematic study on 732 autopsies, including 182 cases of sudden death

A systematic study of an autofluorescence method is described to improve the early histological diagnosis of myocardial ischaemia. Our results on 732 autopsy cases including 182 cases of sudden death show that the autofluorescence examination of haematoxylin and eosin stained sections of the myocardium is not only reliable in the identification of recent ischaemic lesions, but contributes to a better histological evaluation. In 24 cases undetected by white light examination it allowed recognition of ischaemic lesions.

Myofibrillar degeneration--a common type of myocardial lesion and its selective identification by a modified luxol fast blue stain

Myofibrillar degeneration is a very common form of myocardial damage. It occurs as a disseminated lesion after various forms of injury (e.g. association with cardiovascular surgery, raised intracranial pressure). As a localized alteration it surrounds the coagulation necrosis of infarcts. The present study introduces a modification of the Luxol Fast Blue (LFB) stain as a specific marker of myofibrillar degeneration. In formalin-fixed and paraffin-embedded myocardium of human autopsies and biopsies two LFB-reaction types are demonstrable: A) irregular blue transverse bands and B) a diffuse blue staining of the entire myocyte. The first type corresponds to the cross band lesion typical of myofibrillar degeneration. By electron microscopy it consists of dense aggregations of disorganized myofilaments. The second form exhibits diffusely LFB-coloured cells and ultrastructurally an irregular felt-like splitting of myofibrils. The latter represents another, until now unrecognized type of myofibrillar degeneration which is not clearly detectable when using other staining methods. Since a coagulation necrosis is only faintly LFB-positive, this method is not suitable for the detection of early stages of infarcts. The obvious advantages of the LFB-method are: detection of type, amount and distribution pattern of myofibrillar degeneration in low-power-views, even if myocytes are cut transversely, high sensitivity, easy handling and reliability. The affinity of damaged cells for the LFB-stain seems to be related to the pathogenesis of myofibrillar degeneration, in which abundant Ca++-influx plays a primary role.

Determination of potassium/sodium ratio in heart tissue. Evaluation of its use as an index of myocardial ischaemic damage. Comparison with the nitro-BT test

The succinate dehydrogenase method of staining and the determination of the K+/Na+ ratio of heart tissue have been applied to forensic material as a tool for demonstrating early signs of myocardial infarctions. Both methods are controlled by a series of forensic cases dying from causes other than arteriosclerosis of the coronary arteries. Based on an analysis of normal material some factors influencing the K+/Na+ ratio are defined. It is concluded that the determination of the K+/na+ ratio shows more infarcts than the formazan method; however, the evaluation of the K+/Na+ ratio is difficult. The K+/Na+ determination is not recommended for routine use. A possible indication for the use of the K+/Na+ determination together with the formazan test could be cases of instantaneous death by accidents suspected to have been provoked by a fatal heart attack.

Morphology of cardiac nerves in experimental infarction of rat hearts. I. Fluorescence microscopical findings

The effect of ischemia on the catecholamine content and morphology of autonomic cardiac nerves was studied in experimental myocardial infarction in 65 rats with coronary ligation. The area of infarction, of ligation and other regions of the heart were investigated at hourly and daily intervals up to 9 weeks after ligation. During the first 4 h there is a slight reduction of fluorescence in the area of infarction and a focal, inconstant diffusion of adrenergic transmitters shown by Falck method. After 4 h an increasing loss of catecholamines is observed while the fluorescence of the adrenergic nerves in the adjacent myocardium is maintained or even increased. After 8 h the fluorescence of terminal nerve fibres has decreased; such changes also take place in bigger perivascular nerve trunks. After 16 h specifically fluorescent nerves can be identified only weakly. After two days catecholamine fluorescence has faded. The serotonin fluorescence of mast cells is constant except for focal degranulation. In later stages non-specific fluorescence is caused by fatty degeneration of myocardial cells and lipid-laden phagocytes. The results are discussed in respect to the local effects of catecholamines liberated during the early phase of infarction.

Electron microscopical and enzyme histochemical changes in the rat myocardium during prolonged autolysis

The effect on rat myocardium of autolysis at 19 degrees C, for up to 20 days, was studied by electron microscopy and enzyme histochemistry. The enzymes studied included monoamine oxidase (MAO), sytochrome oxidase (CytO), non-specific esterase ((Ns.E.), phosphorylase (P-ase), succinate dehydrogenase (SDH) and various NAD- and NADP-linked dehydrogenases. The myocardium lost its histochemical P-ase activity within a few hours of autolysis, whereas the activity of all other enzymes remained quite normal for at least about 4 days, except that of MAO and SDH, which were normal for about 8 and 12 days, respectively. The myocardial cells lost activity of various enzymes in a patchy manner during prolonged autolysis and practically all histochemical enzyme activity disappeared within 20 days. The early period of autolysis was accompanied by rapid ultrastructural changes of myocardial cells. During prolonged autolysis the gross architecture of the myocardium was lost gradually by the 12th to 20th days. Mitochondria were the organelles most resistant to the effects of autolysis, and numerous mitochondria with morphologically solid inner and outer membranes were seen among the totally disintegrated myocardium 20 days after death. The loss of P-ase activity coincided with the loss of glycogen. The loss of MAO, SDH and CytO activities was not closely related to the morphological preservation of mitochondria, but, in accordance with other enzymes, was more closely related to the disintegration of the over-all myocardial structure. The present results showed that the architecture of the myocardium, and especially that of the mitochondria, was surprisingly resistant to the effects of autolysis at room temperature. Also several enzymes of the myocardium other than those examined so far maintained quite stable histochemically demonstrable activity during prolonged autolysis. These observations give support to the possibility of making the diagnosis of myocardial infarction at postmortem more accurate than with the present morphological and histochemical routine methods.

Chemical and morphological studies of rat myocardium after application of a necrogenic dose of isoproterenol

In male Wistar rats myocardial necroses were produced by application of 80 mg of isoproterenol per kg of body weight. 2 and 48 hours after isoproterenol administration the Na+ and K+ contents were determined. At these times Na+ presented increases of 128 and 83% respectively, and K+ of 13 and 8% respectively as compared to the controls. These results were related to the morphological changes appearing at the same time, and were discussed with references to the literature. Taking edema and vasodilatation into account, the degree of cell damage can be estimated on the basis of the chemical data available.

[Histochemical and histoenzymatic study of experimental myocardial infarction in the rat by temporary and permanent ligation of the left coronary artery (author's transl)]

The evolution of experimental myocardial infarction in the Rat with or without revascularization has been studied histochemically and histoenzymatically in 56 animals sacrified after 1, 6, 12, 24, 48 hrs and 7 days. Following permanent ischemis (14 animals), there appeared an extended transversal infarction marked by the complete disappearance of all phosphorylase activity (P-ase) after the first hour. During the first 6 hrs, changes appeared in succinodeshydrogenase (SHD) and cytochrome oxydase (Cyt-Ox). Glucose-6-phosphodeshydrogenase (G6PDH) presisted until lysis of the necrotic focus. It was possible to define a perinecrotic marginal area in which Pase activity is absent and SDH is granular "G3 in nature, characterized by continuous remodeling in the first 48 hrs. Following temporary ischemia (42 animals) the evolution was marked by rapid tissue reactions and early regression of the marginal zones. After 48 hrs and 7 days of survival, the planimetric evaluation of the infarcted area shows a definite reduction in the size of the infarctus in 50% of cases following removal of the ligature after 6 hrs, and in 66% of cases following removal of the ligature after 1 hr. It would appear probable that the revitalization of certain myocardial areas may extend from the marginal zones as is suggested by the reappearance in these zones several hrs after revascularization of P-ase and SDH activity. On the other hand, it is also true that the early restoration of blood flow does not always prevent the occurrence of an extended infarction. Certain recent observations have shown microcirculatory changes which are secondary to anoxia and should be studied further.