Rivista di istochimica, normale e patologica最新文献

The appreciation and utilization of Histochemistry in Biology varied in the course of time, according to the development of new and more reliable techniques and according to the possibility of checking the results on the basis of rigorous biochemical research. It is well known that the need of histochemistry is best understood when the problem is that of individualizing single cells or groups of cells whose physiology (and biochemistry) is different from that of neighbouring other cells of the same nature, and when it is impossible or not desirable to fractonate such kind of cells or their operative substructures. One of the field of animal biology in which biochemistry has been very successfully applied is that of the study of the differentiation of skeletal muscle fibers, which derive from the fusion of many separate myoblastic cells with possible different genetic potentialities. In this connection, it appears sufficiently clear that the differentiation (or modulation) of fibres in fast and slow, red and white is largely dependent on epigenetic influences and particular on that of the type of neuron with which the fiber is connected. We have sufficient experimental evidence of change in type of muscle fibres following change of the neuronal part of the neuromyone (cross reinnervation, etc.). It is also possible that the neurotic influence is translated only as pattern of excitation and in so far it could be imitated by other sort of stimulation; on the other hand, it is also possible, particularly in young animals, that the state of the muscles and the physiological utilization of them in the whole complex animal behaviour (modifiable by experiment) could influence the differentiation of neurons in the fast and slow types. In any case, any established physiological differentiation among muscle fibres, particularly that reflected by different kinds of contractile proteins and of their ATPase activity, corresponds to a simmetrical differentiation, among motoneurons. In the case of pathology, the histochemical study of muscle fibres has become an unavoidable mean of diagnosis. But some criticism should not be neglected when we face the problem of inferring the nature (neurogenic or non neurogenic) of a myopathy only from the distribution of the lesions among the fiber types of a diseased muscle.

The changes of the charge group density on the cell membrane and the role of the sialic acid residues were studied in the liver cells of rats treated with high doses of isoprenaline in various organs with effects at genetic, structural and metabolic level. The postnatal growth of the rat liver was followed, when a process of polyploidization occurs: IPR treatment in this period is known to accelerate the phenomenon. IPR was injected twice a day intraperitoneally at the dose of 2 mg/100 g of body weight in one or two week courses. The charge group density was evaluated from the electrophoretic mobility pattern of isolated hepatocytes using the Zeiss cell electrophoresis apparatus. The presence and the importance of sialosubstances in the cell membrane was evaluated by comparing the data from normal cells with neuraminidase treated cells; in this situation, the release of sialic acid by neuraminidase produced significant reductions of the cellular electrophoretic mobility. A general increase of the surface charge density, mostly due to the sialic acid fraction, was demonstrated in association with the IPR treatment; this effect was more evident at later times after the end of the stimulation and in animals treated with two courses of IPR. This study evidenced the role of the membrane sialomucinic component during the whole sequence of events induced by IPR treatment at cytological level and leading, among other things, to a mitotic stimulation. In addition, the persistence of the high charge group density should be taken into account even in connection with cell growth, differentiation and hypertrophy.