37 patients undergoing coronary revascularization were randomly assigned to three protocols for intraoperative myocardial protection: hypothermic ventricular fibrillation (HF) (n = 13), multi-dose blood cardioplegia (BCP) (n = 12) and single-dose Bretschneider's crystalloid cardioplegia (CCP) (n = 12). As intraoperative markers of ischemic damage myocardial ultrastructure, ATP, and CP contents were determined in left ventricular biopsy specimens taken before and after cardiac arrest. Release of serum enzymes (CK, CK-MB, LDH, SGOT) was determined pre- and postoperatively. Hemodynamic data were assessed before, during, and after operation. The incidence of low cardiac output, positive inotropic support, intraaortic balloon counterpulsation, peri-operative myocardial infarction, rhythm disturbances, and the rate of spontaneous defibrillation was compared between groups. The results show a better preservation of high energy phosphates in the BCP group as compared to the HF and CCP groups. Myocardial ultrastructure showed moderate ischemic damage in the hypothermic fibrillation group; in contrast, only slightly deteriorated cells were seen after cardiac arrest, when cardioplegia was used. The incidence of rhythm disturbances was 25% for HF and 42% for CCP. In contrast, only 17% of new rhythm disturbances were seen in the BCP group. Functional recovery (i.e. CI and SWI) of hearts protected with BCP was generally greater as compared to HF and CCP. Release of MB-creatine-kinase isoenzyme was higher in the HF group as compared to cardioplegia. Clinical outcome in terms of incidence of peri-operative infarction, positive inotropic support and low cardiac output was superior in the BCP group but not significantly different between groups.(ABSTRACT TRUNCATED AT 250 WORDS)

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A precise electron microscopical distinction between so-called mature and immature mast cell tumours is possible. In immature mast cell tumours, the neoplastic cells contain granules in various phases of development, well-developed ergastoplasm, many free ribosomes, extended Golgi apparatus, complex cytoplasmic membranes, and nuclei with folded nuclear membranes, hypertrophic nucleoli, and finely dispersed chromatin. In mature mast cell tumours, the neoplastic cells have scarce ergastoplasm, fewer free ribosomes, a small Golgi apparatus, some cytoplasmic protrusions, and nuclei with predominantly heterochromatin and only a few folds of the nuclear membrane; the cytoplasmic granules are electron-dense and amorphous or reticular or granular or contain membranous structures. The mature neoplastic cells resemble normal tissue mast cells. In the genesis of granules five phases of maturation can be distinguished. The release of substrate may result from dissolution of granules. In experimental degranulation the release of whole granules may be the immediate result of a relatively strong stress and interference with the cell structure. The intranuclear virus-like structures observed (a small virus containing DNA?) are discussed as a possible oncogenic agent.

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