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Biomedical subjects

A Galanzi

Publications and source records attributed to A Galanzi.

29 records · Page 2Linked to original sources
PubMed1988

Changes in ribonucleoprotein particle and chromatin organization induced by liposomes in isolated nuclei.

Nuclei isolated from rat liver, incubated in the presence of liposomes of different phospholipids, undergo typical modifications: chromatin dispersion and reduction of the interchromatin granules in nuclei incubated with negatively charged liposomes and increase of the chromatin density and of the number and size of the interchromatin granules in nuclei incubated with neutral liposomes. The possibility that the observed modifications are caused by an impairment of the transport and translocation of ribonucleoproteins belonging to the inner nuclear matrix, is suggested by the results obtained by radiotracer techniques on the release of RNA from liposome-incubated nuclei.

Animals↗
PubMed1987

Changes of chromatin organization induced by phospholipids.

Isolated nuclei represent a suitable model for studying the influence of exogenous phospholipids, normally found as minor chromatin components, on the nuclear structure, which, in turn, could be related to the observed modifications of DNA and RNA synthesis. The morphological modifications induced on chromatin RNP granules and nuclear matrix have been analyzed both with conventional thin sectioning and with an original method based on image analysis of freeze-fractured and replicated nuclear samples. The results obtained support the hypothesis that anionic phospholipids, by removing histone H1, induce a transition of the chromatin from solenoid to nucleosome conformation and favour the RNA polymerizing activity which results in an increased release of RNP particles, while neutral phospholipids, probably affecting the matrix structure, partly impare the RNP maturation and transport, with consequent increase of chromatin condensation.

Animals↗
PubMed1986

Electron microscopy microsampling of isolated nuclei sorted by flow cytometry.

This paper describes an efficient method to concentrate for electron microscopic examination minute quantities of subcellular particles obtained by cytofluorimetric sorting. The advantages of this micromethod, based on diafiltration on Millipore filters under constant positive nitrogen pressure, are discussed.

Animals↗
PubMed1986

Ultrastructural organization of freeze-fractured interphase nuclei.

The morphology of intact or membrane-deprived interphase nuclei has been analysed by freeze-fracture electron microscopy. This method appears particularly useful for providing information on the distribution and organisation of chromatin and ribonucleoproteins in the absence of dehydration and embedding artifacts of conventional electron microscope techniques which, among other effects, appear to affect heterochromatin distribution, inducing its aggregation along the nuclear envelope. The main levels of chromatin superstructure, from nucleosome to solenoid fibres, are detectable in the replicas of freeze-fractured nuclei on the basis of the size of their shadow, a parameter particularly suitable for automated image analyses.

Animals↗
PubMed1985

Uptake of tritiated phosphatidylcholine by isolated rat liver nuclei studied by electron microscope autoradiography in albumin embedded specimens.

The transfer of phosphatidylcholine from multilamellar vesicles to isolated rat liver nuclei was studied by means of electron microscope autoradiography. To avoid the possible loss or the artifactual redistribution of the phospholipid occurring during dehydration with organic solvents and plastic embedding, the fixed specimens were embedded in aqueous albumin, which was then hardened by glutaraldehyde and dehydrated physically. The quantitative analyses of the autoradiograms demonstrated that part of the labelled phosphatidylcholine was taken up by the isolated nuclei and was transferred inside the nucleoplasm. The uptake corresponded to the loss of the vesicular arrangement, probably owing to the formation of a lipoprotein complex with the nuclear proteins. The results provide evidence that the lipid-induced changes of transcriptional activity occur upon the actual interaction of the exogenous phospholipid with the inner nuclear components.

Albumins↗
PubMed1983

Association between centriole and nuclear matrix in human lymphocytes.

Nuclear matrices, purified from normal and chronic lymphocytic leukemia lymphocytes, exhibit a close association with the centriole. This finding suggests that the nuclear and cytoplasmic skeletal systems are linked by transmembrane connections represented by nuclear matrix constituents. This could account for the observed synchrony between transformations of the centriole and particular nuclear events which take place during the cell cycle and suggests that the nuclear matrix, besides being involved in DNA replication and chromosome condensation, should affect the centriole cycle which controls the cytoskeleton organization.

Cell Division↗
PubMed1981

[Characterization of the convoluted seminiferous tubule wall. II. Ultrastructural alteration after testis retention in the abdominal cavity].

An ultrastructural analysis has been carried out on the seminiferous tubules after different periods of stay of the rat testis in the abdominal cavity. With respect to control rats, no changes are detectable after 5 days, while after 15 and 30 days considerable modifications take place. A number of cellular features are modified, such as the nuclear shape and the perinuclear vesicles, while the cytoplasmic filaments show a less ordered appearance. In addition, the extracellular amorphous matrix undergoes a large increase, due either to an enhanced production or to a reduced turnover related with a lowered cell activity.

Animals↗
PubMed1981

[Characterization of the convoluted seminiferous tubule wall. I. Ultrastructural aspects after the ligation of the vas deferens and the efferent tubules].

The structure of the wall of the rat seminiferous tubules has been studied by electron microscopy. No significant modifications have been revealed after the ligature of the vas deferens while on the contrary the ligature of the efferent ductules produces a reduction of the contractile filaments and of the pinocytosis vesicles, as well as an increase of the amount of collagen fibers in the basal membrane.

Animals↗
PubMed1980

[Microscopic research on arachnoid villi in various mammals].

The sagittal sinus in the man, dog, cat and rabbit was studied; we have noted remarkable histological differences within the zoological succession in the system of discharge of the cerebrospinal fluid in the venous system. The differences, probably, are chargeable to the different metabolic encephalic exigences which in the man are exalted and which justify the presence of the more complicated structures.

Animals↗