Introduction: human pathology within the broad scope of comparative pathology.

Pathologic integration is the basic phenomenon of comparative pathology. Since man evolved as earth's most influential species, he was unequally influenced the progression and prevention of diseases in himself and other species. This has both positive and negative ramifications. Positive influences have been life-style, the prolongation of life under healthy conditions and medical progress as seen in the treatment of diabetes mellitus, dental hygiene and other factors, such as the decrease of infectious and parasitic diseases, which are still dominating factors in developing nations. Negative influences are side effects of medical treatments, the appearance of occupational, and certain recreational diseases. These are the pathologic effects of man's life-style to which car accidents, smoking and other factors can be added. Different species are affected by environmental changes such as pollution, ozone, acidic rain, polluted food, and transmission of different diseases from one species to another. Interspecies-specifically the direct influence of man in the extermination of other species, or the indirect influence such as through pollutants in the environment producing chain reactions in different species, can be distinguished. The physical environment has been changed as can be seen in air pollution in large cities, the damage to the ozone layer and the increase of malignant melanoma in certain regions of western Australia. The industrialized nations are dominated by non-infectious diseases such as atherosclerosis and neoplasms, whereas in the developing nations parasitic and infectious diseases stand in the fore-front. Particular diseases like acquired immunodeficiency syndrome increase in both types of nations. These diseases may have developed from other species, e.g. the plague which was originally a disease of rodents, especially rats where it was transmitted by the flea, Xenopsylla cheopis, Rothschild. The principle of foremost importance is the disruption of biologic integration of normal processes leading to different types of pathologic progression. A typical problem affecting man and many other fellow species is crowding. Man's pathology and the pathology of other species exhibit continued integration which is the central problem for understanding diseases where similar functions are performed by various structures, such as is the case in gaseous exchange, or differences in size and life span. The broad spectrum of comparative pathology which centers around human pathology provides a source of increased knowledge for a better understanding of diseases. The present issue is based on the two symposia organized by the International Society for the Study of Comparative Ongology during the Fifth International Conference of Anticancer Research, 17-22 October 1995, Corfu, Greece.