Acta biologica Academiae Scientiarum Hungaricae最新文献

A cold-resistant (cr) variant of mouse L fibroblasts called LC3, isolated by repeated cooling of the parent population for several weeks at 4 degrees C, differed from the wild-type cells in morphology and function. Microcinematographic records demonstrate that their motility is markedly reduced when compared with that of the L cells. They enter mitosis at 30 degrees C, at 37 degrees C and at 39 degrees C, but they finish cytodieresis only at 30 degrees C. At the higher temperatures, they reach anaphase, but then the daughter cells fuse and form polykaryons. At 39 degrees C, bizarre forms with large undulating membranes predominate in the damaged population. The cr cells may be used as a model for the study of temperature adaptations on cellular level, as well as for the analysis of the relations between membrane properties, cold resistance and cell cycle control.

There are numerous aldehyde fuchsin (AF)-positive, neurosecretory cells of medium size (A cells) and a small number of large, AF-negative neurons (B cells) in the cortical layer of the cerebral ganglion. In the subesophageal ganglion, symmetrical groups of AF-positive cells lie ventrally. The peroxidase--antiperoxidase (PAP) method was used for the immunocytochemical study of substance P and ACTH in these ganglia. In addition, the presence of L-enkephalin and alpha endorphin could be confirmed. Using rabbit antibodies to substance P we found small immunoreactive neurons among negative A and B cells in the cerebral ganglion. The processes of these immunoreactive cells could be traced to the subcortical synaptic neuropil. With antibodies to ACTH, activity was visible in perikarya similar in size to A neurons. A part of the nerve terminals of the synaptic zone, some of the B neurons and further several nerve cells of the subesophageal ganglion reacted positively. Successive demonstration of substance P and ACTH on the same section showed that the two materials occurred in different cell types. Using antiopsin antibody in an indirect immunocytochemical test we observed strong reaction in numerous medium-sized perikarya and in nerve fibres of the synaptic zone of the cerebral ganglion, further in some neurons of the subesophageal and abdominal ganglia. In contrast to this result, the photoreceptor cells of the prostomium and cerebral ganglion were negative. Presumably, substance P is present in a perikaryon type hitherto unrecognized while ACTH and antiopsin reactions seem to be located first of all in A cells.

Tissue culture and transplantation techniques can be used to analyse the relationship between ageing and cancer. In vitro transformation experiments show that the transformation frequency in mesenchymal cells and salivary gland epithelium does not seem to be age-associated but in the bladder old epithelium can be transformed much more frequently than young. Preliminary transplantation experiments confirm this relationship. These experiments suggest that the increased age susceptibility is tissue dependent.

The effect of reduced blood and adrenal cholesterol levels on adrenocortical lipid droplets have been examined by treating adult rats with 4-amino-pyrazolo-(3,4 d) pyrimidine (4-APP), a drug that inhibits hepatic secretion of lipoproteins. Lowering the blood cholesterol level and the cholesterol content of the adrenals was associated with a marked reduction in the lipid droplets and with a simultaneous increase in their electron density in the inner cortical zones. In the zona glomerulosa cells, no perceptible differences were found in the quantity and morphology of lipid droplets. These data suggest that reduced blood and adrenal cholesterol levels do not affect lipids located in the zona glomerulosa and in the inner cortical zones in the same way, probably due to differences in their intracellular lipid dynamism. Noteworthy, that in spite of the marked lipid depletion, the adrenal glands retained their responsiveness to ACTH stimulation.

In cats the distal and proximal stumps of transected postganglionic bundles of the celiac ganglion were studied by the Falck--Hillarp histofluorescence methods 72 hrs after transection. Non-degenerated monoaminergic axon terminals were found in the distal stump. It is assumed that these axons reach the celiac ganglion and inhibit the principal ganglion cells.

Pituitaries were taken from human fetuses between the 6th and 30th weeks of gestation. Organ and monolayer cultures were prepared. The fine structure of the cultures was examined by electron microscopy and their basal and stimulated ACTH release were studied by radioimmunoassay as a function of time in vitro. It was shown that pituitaries taken from the first trimester of gestation have a capacity of self-differentiation; i.e. there was an increase in the number of cells filled with secretory granules and there was an increase in the number of granules per cell. In contrast, pituitaries taken from older embryos have been losing their secretory granules during the cultivation. We failed to demonstrate any corticotropin responsiveness in pituitary cultures prepared from the 6 to 7-week-old embryos. ACTH release could be stimulated from the 10th week of gestation but in slight measure. Pituitary taken from 16-week-old fetuses revealed an adult-like responsiveness to corticotropin.

The distal articular surface of the femur was surgically removed in 57 dogs. Succinate dehydrogenase and cytochrome oxidase activities were assayed on postoperative days 7, 20, 26, 33 and 70 in the regenerating, chondrifying articular surface and in the granulation tissue adhering to the capsule. In the 70-day samples, the cyanide-induced inhibition of oxygen consumption was determined and enzyme histochemical reactions (cytochrome oxidase, monoamine oxidase, xanthine oxidase, peroxidase and "catalase") were performed. The succinate dehydrogenase activity was the highest in the early postoperative stage in both tissues. This was followed by a definite decrease and a subsequent significant increase in activity when chondrification took place. Measurement of cytochrome oxidase activity could not reveal any convincing result, presumably because of the properties of the tissues studied. The oxygen consumption by the chondrifying articular surface at 70 days was inhibited to about 50% by cyanide, and about 90% inhibition was observed in the tissue adhering to the capsule. The cells of the regenerating articular surface possess cytochrome oxidase and a cyanide- (and sodium azide-) resistant oxidase activity. The enzyme activity of the cartilaginous islets exceeded that of their connective tissue environment. The cytochrome oxidase activity increased in the cells during cartilage differentiation. Presumably, some further cyanide-sensitive and cyanide-resistant oxidases are present in chondroblasts and young chondrocytes.