Rivista di istochimica, normale e patologica最新文献

The research was carried out on the vorestomachs, abomasum and on the various tracts of gut of adult Cattle, Sheep and Goat, because Ruminants, not previously studied with respect to this problem, have, as is well known, particular morpho-functional characteristics of the digestive system. The results can be synthetized as follows: 1) either "EC" (5-HT-producing) or "APUD" cells (peptide hormones-producing) are not demonstrable in the vorestomachs. 2) "EC" cells are present in the various areas of abomasum (particularly numerous in the fundus glands) and in the different tracts of the gut (predominantly in the duodenum and in the rectum). 3) In the "APUD" cells of the abomasum gastrin-producing "G" cells are certainly demonstrable. They are present only in the pyloric glands, where they prevail in the middle third. Only in the cattle, cells which have all the histochemical characteristics of "G" cells, but are quite morphologically different, are also present in the same area. An interesting peculiarity seems to be the reduced number of "APUD" cells, compared with that of Monogastrics: it was impossible, in fact, to demonstrate some cells ("A", "A-like","X", "D", "D1", "ECL") which are described by other Authors in the stomach of various Mammals. 4) In the small intestine, endocrine cells, probably heterogenous are present, resulting more numerous in the duodenum. 5) In the coecum, colon and rectum, cells comparable to enteroglucagon-producing "EG" cells, are present; they are particularly numerous in the rectum, where cells similar to "H" cells are also present.

The Authors have studied some aspects of the differentiation of gastric mucosa, during the prenatal and postnatal development in man and mouse. They have demonstrated that in both species the first elements of glandular rudiments can be already recognised, owing to the richness of their mitochondrial store, as parietal cells, where oxireductase activities are already present. The functional differentiation in the membrane of such elements takes place later on: from the point of view of the function the parietal cell can then be considered as completely differentiated. Chief cells, on the contrary, define their morphological and functional characters starting from the fifth month of foetal life. At any rate, at least for the studied characters, the gland store of human gastric mucosa, at birth and in the adult, is exactly alike.

Polyacrylamide gel electrophoresis of sera obtained from normal individuals shows an incidence (33%) of double and triple bands of alkaline phosphatase in the beta-lipoprotein zone in addition to the usual ones near beta-globulin. The correlation between the occurrence of a slow moving band in addition to the normal one, of different intensities, p+ and p++ with O and B groups has been further confirmed. No relationship was observed between the width or the number of bands with the total amount of alkaline prosphatase as determined biochemically.

In the byosinthesis of glycosaminoglycans, UDP-glucose is utilized by two enzymes: UDP-glucose dehydrogenase which produces UDP-glucuronic acid (chondroitin sulphate precursor), and UDP-glucose 4'-epimerase which produces UDP-galactose (keratan sulphate precursor). The mechanisms regulating these two reactions have particular interest mainly considering that many connective tissues can modify its glycosaminoglycan production with aging; it is well-known that cartilage of young animals synthesizes almost exclusively chondroitin sulphate while cartilage of old animals synthesizes both chrondroitin sulphate and keratan sulphate. The kinetic parameters of both enzymes utilizing UDP-glucose have been recently investigated and some mechanisms responsible for UDP-glucose utilization in glycosaminoglycan biosynthesis have been evidenced. Under histoenzymological viewpoint, we have confirmed the inhibiting effect of UDP-xilose on UDP-glucose dehydrogenase and the possible role of such nucleotide in aging processes of cartilage. In order to study this problem even by a histoenzymological approach, an original method for histochemical determination of UDP-glucose 4'-epimerase activity in connective tissue cells was developed. This method seem to be more sensitive than that described by other authors. In standard conditions the sections of the frozen tissue were incubated in Tris-HCL buffer, pH 8.8 (Tris concentration 0.025 M), containing 0.5 mM UDP-galactose, 2 mM NAD, 0.6mM NBT and an excess of UDP-glucose dehydrogenase (about 300 mU). Control experiments in the absence of UDP-galactose, UDP-glucose dehydrogenase and in the absence of both UDP-galactose an- UDP-glucose dehydrogenase were also carried out. Under our experimental conditions, UDP-glucose 4'-epimerase present in the cells epimerizes UDP-galactose (added in the incubation mixture) to UDP-glucose which can bo oxidized by the excess of UDP-glucose dehydrogenase to UDP-glucuronic acid with a consequent NADH formation. The NADH formed is able to reduce and precipitate NBT. As a control of experimental sistem, we have determined the increase in O.D. at 525 nm of a reaction solution that was incubated directly in the spectrophotometer cuvette, at 37 degrees C with UDP-galactose 0.2 mM, NAD 2 mM, NBT 0.6 mM, 200 mU of UDP-glucose, dehydrogenase, 400mU of UDP-glucose 4'-epimerase and Tris HCL buffer pH 8.8 to a final volume of 1 ml. Histoenzymological and biochemical results demonstrate that this method is specific for and sensitive to UDP-glucose 4'-epimerase activity.

The Xenopus laevis Daud. genome offers a stimulating model of a chromatin (Davidson et al., 1975) in which a high ratio of repetitious DNA sequences has been recorded (45% of total genome according to Davidson et al., 1975). We have studied cytochemically this model "in situ", on the erythrocytes of air-dried smears of peripheral blood. The cells, which are non-dividing and not engaged in DNA reduplication, constitute almost hypothetically a homogeneous class constantly in G1 phase of the cellular cycle. Our methods are: a) analysis on the curves of Feulgen hydrolysis kinetics to attempt to find the depurination and depolymerisation patterns of DNA according to Andersson et al. (1975); b) determination of the DNA resistence ratio to chemical denaturation with a quantitative relative microdensitometric determination of methyl-green staining, according to Scott (1967) specific technical conditions. For comparison, qualitative and preliminarly subjective control determinations have been made with acridine-orange in correspondent denaturation conditions. Both the a) and b) methods have been performed with and without previous HCl dehystonisation and with and without formaldehyde pretreatment. The results with the a) and b) methods have not yet been theoretically compared and the possibility of an approach to this correlation is discussed here as a tool for a possible cytochemical quantitative measure of the nuclear fraction of repetitious DNA "in situ".