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A comparison was made of the sensitivity of ECG, ultrastructural heart pathology, and plasma enzymes CK-MB and alpha-HBDH as methods to assess doxorubicin cardiotoxicity in adult beagle dogs given doxorubicin 30 mg/m2 i.v. once a week for three times. A progressive increase in JT and QT intervals, in corrected JT (JTc) and QT (QTc) intervals as well as a reduction in both T wave amplitude and RR duration, were observed in doxorubicin-treated dogs; the electrocardiogram (ECG) abnormalities were associated with doxorubicin-induced ultrastructural changes in cardiac tissue, consisting of dilation of the sarcoplasmic reticulum, multiform, flasklike invaginations of T-tubules containing electrondense material, and interruption of the junctional sarcoplasmic reticulum, which became more severe as the observation period progressed. On the contrary, doxorubicin treatment was associated with transient changes in plasma CK-MB and alpha-HBDH, which were unrelated to the severity of chronic cardiotoxicity. Overall results suggest that the monitoring of the ECG parameters related to the repolarization of the cardiac muscle, and particularly JT and JTc, might be regarded as a noninvasive method for the study of doxorubicin cardiotoxocity in the dog.

A morphometric study was performed in dog atria to assess the effects of both single and repeated doses of doxorubicin on specific granules containing the natriuretic factor. Male beagle dogs were divided into 4 groups and treated i.v. as follows: groups A and B were controls and received isotonic saline; group C was given doxorubicin 2.4 mg/kg in a single injection; group D received doxorubicin 1.2 mg/kg once a week for 3 consecutive weeks. Samples of left atrium were taken 8 hours (groups A and C) or 28 days (groups B and D) after the last dose, and examined by the electron microscope. Compared with controls, the atrial tissue of group C dogs showed a significant increase in the number of specific granules; by contrast, the granularity was found to decrease significantly in the atria from group D dogs. These observations indicate a significant biphasic effect of doxorubicin on specific atrial granules of dog heart. The increase in granule density might be due to a block of the secretory process which is dependent on the metabolic energy supply. The reduction in cardiomyocyte granularity may be ascribed to the impairment of nucleic acid and protein synthesis induced by doxorubicin. Such alterations may play a significant role in doxorubicin-induced cardiovascular toxicity.

The Authors report a chromosome study carried out on pleural effusion cells from metastases of oat cell carcinoma. They observed a double cell clone: the former, with 44 chromosomes, with various alterations of the karyotype and a big acrocentric "marker", the latter, with 45 chromosomes with various alterations of the karyotype and a big submetacentric "marker". From these observations the Authors draw some interpretative considerations.

Some characteristics of the fluorescence of cardiac human lipofuscin and, in connection, the acid phosphatase activity were studied. The presence of acid phosphatase reaction product was demonstrated in lipofuscin granulations. Two types of fluorescence spectra with a maximal emission peak at 580 nm. and 600-610 nm. respectively, were obtained. A photodecomposition of average intensity was present and, at same time, shifts the maximal emission peaks were noticed. The data obtained were discussed in relation with the identification of the fluorescent substance.

A brief explanation of the dangers inherent in the indiscriminate use of ionising radiations and a description of the modality of action of cell radiations are followed by an account of the significance of lesions of the genetic inheritance. Data obtained from the irradiation of human chromosomes are also presented. In these experiments, the effects of scalar doses on in vitro peripheral blood cultures and 'in vivo' on patients irradiated in the course of treatment of the lumbosacral area were studied. The radioprotective activity of various pharmacological agents was measured by means of an original method and the results obtained are discussed.

The results of chromosomal studies in a patient with XY/XO mosaic and acute myeloblastic leukaemia are presented. The onset of leukaemia was associated with a further chromosomal anomaly consisting in the loss of a small group G acrocentric.