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Biomedical subjects

F Marinelli

Publications and source records attributed to F Marinelli.

At least 19 recordsLinked to original sources
PubMed1991

Structural and functional modifications induced by ketamine on synaptosomes in the rat.

This study correlates previous observations on the effects of a general anaesthetic (2-chlorophenyl-2-methylaminocyclohexanone, trade name Ketalar), administered in vivo on the functional properties of synaptosomes from the brain of the rat, with structural modifications detected using freeze-fracture electron microscopy. The anaesthetized rats exhibited a fluidization of the synaptic membranes, as probed by stearic acid spin labels, accompanied by a decrease in the activity of acetylcholinesterase. The freeze-fracture images of synaptosomes from anaesthetized rats showed a clear statistical increase in the number of vesicles with aggregated intramembrane particles, without any significant change of the particle diameter. The hypothesis that a perturbation of the lipid protein interaction is a primary effect, in the mechanism of action of anaesthetics, is supported at present only by indirect evidence.

Acetylcholinesterase↗
PubMed1990

Image analysis of the chromatin organization in the nuclear domains of freeze fractured hepatocytes and lymphocytes.

The complex organization of the interphase nucleus can be analyzed, by way of thin sectioning and also freeze-fracture. This approach has previously been utilized in association with image analysis to quantitatively describe the organization of isolated rat liver nuclei and nuclear matrices. The main nuclear domains which, in section, present marked differences due to their electron-density, can be identified in replicas with more complex procedures, based on the quantitative evaluation of the number of particles per unit area and mainly by using image analysis. A quantitative analysis of the nuclear substructures has been performed by way of image analysis on in situ nuclei of freeze-fractured cells presenting marked differences in the heterochromatin quantity, such as hepatocytes and lymphocytes. The replicated nuclear particles have been classified according to their diameter and the obtained histograms have been quantitatively evaluated. The nuclear domains, heterochromatin, interchromatin, nucleolus, present characteristic ratios among the three main classes of particles; that is, ribonucleoproteins, solenoid filaments and solenoid fibre aggregates. The typical patterns of the nuclear domains can be further stressed by selecting a single class of particles and by examining its topographic localization. While interchromatin and nucleolar domains present a similar quantitative pattern in hepatocytes and lymphocytes, the heterochromatin of lymphocytes contains a significative higher percentage of solenoid aggregates than that of hepatocytes.

Animals↗
PubMed1989

Morphometric study of chromatin pattern in freeze-fractured rat liver nuclei during malignancy evolution.

Computerized image analysis was performed on freeze-fractured nuclei isolated from normal rat liver and rat liver with diethylnitrosamine induced hepatocarcinomas. Chromatin particles belonging to heterochromatin and interchromatin nuclear regions were measured, distributed into histograms and statistically processed. The ratio between nucleosome filaments (5-10 nm range diameter) and solenoid fibres (25-35 nm range) and Tukey's fitting line were calculated. The N/S ratio shows an inverse trend in treated nuclear samples with respect to the controls indicating that the malignancy progression is accompanied by characteristic derangement of the chromatin arrangement which can be evaluated by morphometric analysis.

Animals↗
PubMed1989

[Staphylococcus haemolyticus. Bacterial resistance to teicoplanin and associated morpho-structural aspects].

To improve our understanding of the bases of teicoplanin resistance we studied a "one-step" mutant of S. haemolyticus from a morphological point of view. The results show that the organization of peptidoglycan is altered in the resistant S. haemolyticus strain. It is suggested that the alterations, including the spongier cell wall structure, may prevent the teicoplanin from reaching its target.

Anti-Bacterial Agents↗
PubMed1988

Effect of general anesthesia on syncytiotrophoblast plasma membranes from human placenta.

This investigation shows that a general anesthetic produces similar effects in vivo and in vitro. Anesthesia with a barbituric drug, Thiopental, induces an increase in membrane fluidity and a decrease in the activity of acetylcholinesterase in syncytiotrophoblast plasma membranes (SPM) obtained from placentas after caesarean section. The same effects can be reproduced in vitro after anesthetic addition to the isolated plasma membranes. Morphological and freeze-fracturing studies also suggest that membrane protein components are affected by anesthetics.

Acetylcholinesterase↗
PubMed1987

Sampling in diagnostic morphometry: the influence of variation sources.

The variation sources relevant to a diagnostic morphometric study were analysed. The influence of each source was estimated in two experiments, performed in systems applying computer assisted interactive morphometry. In the first experiment one observer measured the areas of a large number of nuclei in a section from a grade II transitional cell carcinoma of the bladder. In the second experiment two groups of researchers, from Ancona and Kuopio, measured one field from five different samples of transitional cell tumours (including the case of grade II carcinoma). It turned out that pure interobserver variation was responsible for about a half of the total variation present in the diagnostic system. When the variation characteristics of the diagnostic system had been determined, the number of nuclei that had to be measured to reach a defined level of accuracy could be estimated. Such an estimate was also dependent on the predefined expectancy probability of reaching a correct estimate. The study showed that group morphometry (statistical, investigative morphometry) and diagnostic morphometry must be understood as two different approaches in histopathology. By applying group morphometry, good research results can be gathered with cruder measurements than in diagnostic morphometry. Because investigations in group morphometry are more standardized than in diagnostic morphometry, a larger number of structures has to be measured in diagnostic histopathology for the same level of accuracy.

Analysis of Variance↗
PubMed1987

Detection of mucus glycoconjugates in human conjunctiva by using the lectin-colloidal gold technique in TEM. III. A quantitative study in asymptomatic contact lens wearers.

We characterized the mucus glycoconjugates produced by goblet and non-goblet epithelial cells in asymptomatic contact lens (CL) wearers. We employed four lectins (proteins of vegetal origin which specifically recognize glycosidic residues: WGA, PNA, SBA and ConA) conjugated with colloidal gold as ultrastructural marker, at Transmission Electron Microscopy. A computerized quantitative analysis was carried out in order to compare the results from the CL wearers to those from the control patients. Goblet cells produce different amount of glycosidic residues, in particular, a significant decrease in the distribution of sialic acid, N-acetylglucosamine, N-acetylgalactosamine, galactose-N-acetylgalactosamine and mannose was observed. The content of glycosidic residues in the mucus vesicles of the non-goblet epithelial cells appeared unchanged as to the normal situation. We speculate that the CL could possibly contribute to the failure of the tear film stability by altering the production of mucus.

Adult↗
PubMed1987

Modifications of the chromatin arrangement induced by ethidium bromide in isolated nuclei, analyzed by electron microscopy and flow cytometry.

Ethidium bromide (EB) is widely used for investigating the DNA conformation in chromatin both with conventional and cytofluorimetric techniques. Since the interaction of the dye with DNA should result in structural deformations which can be different in isolated or in situ chromatin, a study has been performed on the effects caused by different amounts of EB and the analogous propidium iodide on isolated nuclei, in which chromatin maintains its native relationships with the other nuclear structures (envelope, nucleolus, interchromatin RNP, nuclear matrix). The results obtained by comparing ultrastructural observations in thin sections and in freeze-fracturing with conformational analysis in multiparameter flow cytometry indicate that the phenanthridinic fluorochromes, especially at the high concentrations used for cytofluorimetric analyses, cause deep rearrangements of the chromatin in situ. These effects consist both in aggregation and condensation of the fibers into the dense chromatin domains, and in an increase of the supernucleosomal configuration associated with an enlargement of interchromatin spaces in which the RNP particles appear particularly evident. These results, discussed with those available on isolated chromatin, suggest that any unwinding effect of the intercalating dyes on the DNA cause a general condensation of chromatin as a consequence of the constraints which characterize the organization of the chromatin inside the nucleus.

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

Morphometric analysis and topological organization of nuclear matrix in freeze-fractured electron microscopy.

The ultrastructural organization of nuclear matrix, purified from intact or membrane-denuded rat liver nuclei, has been analysed by means of freeze-fracturing technique. This method avoids dehydration and embedding which, in conventional thin sectioning, partly distort or mask the matrix ultrastructure. The various matrix components, and mainly the peripheral lamina and the inner network revealed complex arrangements undetectable with conventional techniques. Morphometric analyses performed with a Texture Analysis System (TAS) Leitz, allowed to obtain precise information on the matrix constituents, based on the histograms of their size distribution. These textural characteristics have been utilized in order to identify, by means of a particular computer programme, the putative matrix localization within intact freeze-fractured nuclei.

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↗
PubMed1986

Benign and malignant mesothelial lesions of the pleura: quantitative study.

Benign and malignant mesothelial lesions of the pleura are quantitatively studied using a Leitz TAS image analyzing system. The Feulgen fast green staining method allows performing on the same cell measurements of the shape and size of the nucleus, the size of the nucleolus and the content of DNA. Numerical data are studied in a multivariate statistical analysis in order to obtain the probability of the morphometric diagnosis in each case. Results demonstrate that the most important measurements are the percentage of cells with evident nucleolus, the nuclear perimeter and the standard deviation of the DNA content, and that these measurements give a correct diagnosis in all cases.

Analysis of Variance↗
PubMed1986

Observer variation in interactive computerized morphometry.

The validity of a test system in morphometric histopathology depends on the variation sources involved. Biological variation is one of the variation sources, but is also the object to be studied with morphometry. We studied the variation sources in interactive computerized morphometry in two test systems involving two different commercially available image analyzers. The measurements were made on nuclei in a microscopic field of 5 transitional cell tumors (papilloma and WHO grade I-III carcinomas) of the urinary bladder. It turned out that different observers selected a variable number of nuclei for measurements, the coefficient of variation (CV) in the number of nuclei being 11-11.5%. Mean CV in nuclear perimeter measurements was 4.4-4.8%, and in nuclear area measurements 8.2-8.6%. The variation in measurements by 1 observer was smaller, the CV values being 2.8% for the number of nuclei, 1.2% for nuclear perimeter, and 2.4% for nuclear area. The results showed that interobserver variation can be considerable in these systems. It is suggested that special sampling rules should be tested with the idea of finding the relevant approach with the smallest interobserver variation.

Carcinoma, Transitional Cell↗
PubMed1986

Morphometric and topologic analysis of freeze-fractured interphase nuclei.

Interphase rat liver nuclei were studied by freeze fracturing followed by electron microscopic observations. This method permits information on the native organization of the nuclear components in the hydrated state to be obtained. Morphometric analyses, performed with a Leitz Texture Analysis System, gave precise information on the different nuclear components, based on the histograms of their size distribution in heterochromatin, interchromatin and nucleolar areas. The textural characteristics were analyzed by computer to determine the topologic distribution of the solenoid chromatin fibers, the nucleosome filaments and the ribonucleoproteins in the different nuclear domains.

Animals↗
PubMed1985

Noninvasive papillary transitional-cell tumors. Karyometric and DNA-content analysis.

An investigation was undertaken to quantify and correlate the nuclear and DNA-content modifications in the different grades of noninvasive urothelial papillary carcinoma. Nuclear area and a roundness factor were studied by histomorphometry in 35 cases, and the DNA content was analyzed in 27 cases. The values of the nuclear area and the roundness factor increased from normal-looking urothelium to grade 3 tumors. The DNA-content analysis indicated a progressive change of ploidy and the presence of an aneuploid (greater than 4c) population in some of the grade 2 and grade 3 lesions. A high coefficient of correlation between the nuclear abnormalities and the DNA content was found.

Aneuploidy↗