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Biomedical subjects

G Bottiroli

Publications and source records attributed to G Bottiroli.

17 recordsLinked to original sources
PubMed1992

Light-induced fluorescence spectroscopy of adenomas, adenocarcinomas and non-neoplastic mucosa in human colon. I. In vitro measurements.

In an attempt to evaluate whether induced fluorescence could be exploited to discriminate neoplastic from non-neoplastic tissue, fluorescence spectroscopy was performed at 450-800 nm on 83 biopsy specimens of colonic mucosa. Measurements showed that fluorescence spectra of adenoma, adenocarcinoma and non-neoplastic mucosa manifest dissimilar patterns. Nine variables, whose photophysical and/or biological bases need further investigation, were derived from the spectra. Discriminant functions between the groups of lesions were determined by using a stepwise discriminant analysis. The diagnostic test had a sensitivity of 80.6% and 88.2%, and a specificity of 90.5% and 95.2% in discriminating neoplastic from non-neoplastic mucosa and adenoma from non-neoplastic mucosa respectively. These results suggest that fluorescence spectroscopy has the potential to improve endoscopic diagnosis of premalignant and malignant lesions of colonic mucosa.

Adenocarcinoma↗
PubMed1992

Comparative studies on the effects of doxorubicin and differentiation inducing agents on B16 melanoma cells.

The differentiation-inducing activity of doxorubicin on B16 melanoma cells grown in vitro was compared with that of other known differentiation inducers, such as theophylline, retinoic acid, and melanocyte-stimulating hormone (MSH). At drug concentrations resulting in cytostatic effects, doxorubicin and theophylline induced morphological changes (dendritic-like structures with a terminal melanin granule) with an enhancement of total melanin content and tyrosinase activity. Retinoic acid did not alter melanin content and cell morphology, although it affected cell growth. MSH enhanced total melanin content and tyrosinase activity, with no significant morphological changes. Flow cytometric analysis showed that MSH led to an accumulation of cells in G1 phase whereas doxorubicin induced an accumulation of cells in G2 + M. Studies on DNA content in doxorubicin-treated cells, selected on the basis of a morphologically differentiated pattern, showed a clustering of these cells in G2 + M, probably due to a cytokinesis block. Thus doxorubicin can induce cell differentiation comparable with other differentiation inducers.

Animals↗
PubMed1992

Distribution of di-sulfonated aluminum phthalocyanine and Photofrin II in living cells: a comparative fluorometric study.

Microspectrofluorometric and fluorescence imaging techniques have been employed to study the internalization and intracellular distribution of both Photofrin II, an experimental drug used in photodynamic therapy, and di-sulfonated aluminum phthalocyanine, a very promising photosensitizer. The results obtained by microscopic techniques in living cells have been compared with those obtained in solution on cell extracts. Experimental results indicated that the complexity of the drug-cell interaction can be explained according to the chemico-physical nature of the drugs. In particular, the presence of both monomeric and aggregated fractions, which are supposed to be internalized through different mechanisms, accounts for the intracellular distributions observed for both drugs, depending on the treatment conditions. Equilibria among the drug fractions take place within the cells, resulting in the persistence of the intracellular fluorescence. On the whole, the behavior of the two drugs appears very similar, except for some aspects related to the intracellular distribution, which can be explained in terms of different degree of lipophilicity of the drugs.

Cells, Cultured↗
PubMed1991

Changes in cell cycle and chromatin distribution in C6 glioma cells treated by dibutyryl cyclic AMP.

C6 glioma cells in culture were treated with 1 mM dibutyryl cyclic AMP (Db-cAMP) for 5, 8, 24 and 72 h. The cells were labelled with [3H]-thymidine before either the end, or the beginning, of the Db-cAMP treatment. The cell cycle passage was monitored by the simultaneous determination of DNA content and DNA synthesis in propidium iodide stained autoradiograms. The data revealed an early (t less than or equal to 3-8 h) and moderate inhibitory effect of Db-cAMP on all phases of the cell cycle except mitosis; some cells (2%) were completely blocked in the S phase. Later (8 less than t less than 24-72 h), the cycling of a substantial part of the population became inhibited in G1 phase. Microdensitometric texture analysis of Feulgen-stained nuclei, performed 24 h after administration of Db-cAMP, showed a higher inhomogeneity of the DNA distribution in cell nuclei, caused by the condensation of a part of the chromatin. This may reflect either changes in genome expression taking part in the process of cAMP induced differentiation or transit of some cells into quiescent G0 or S0 phases.

Animals↗
PubMed1990

Differences in the organization and chromosomal allocation of satellite DNA between the European long tailed house mice Mus domesticus and Mus musculus.

We compared the organization of satellite DNA (stDNA) and its chromosomal allocation in Mus domesticus and in Mus musculus. The two stDNAs show similar restriction fragment profiles after digestion (probed with M. domesticus stDNA) with some endonucleases of which restriction sequences are present in the 230-240 bp repetitive unit of the M. domesticus stDNA. In contrast, EcoRI digestion reveals that M. musculus stDNA lacks most of the GAATTC restriction sites, particularly at the level of the half-monomer. The chromosome distribution of stDNA (revealed by an M. domesticus stDNA probe) shows different patterns in the M. domesticus and M. musculus karyotypes, with about 60% of M. domesticus stDNA retained in the M. musculus genome. It is particularly noteworthy that the pericentromeric regions of M. musculus chromosomes 1 and X are totally devoid of M. domesticus stDNA sequences. In both groups, the differences in energy transfer between the stDNA-bound fluorochromes Hoechst 33258 and propidium iodide suggest that AT-rich repeated sequences have a much more clustered array in the M. domesticus stDNA, as if they are organized in tandem repeats longer than those of M. musculus. Considering the data as a whole, it seems likely that the evolutionary paths of the two stDNAs diverged after the generation of the ancestral 230-240 bp stDNA repetitive unit through the amplification, in the M. domesticus genome, of a family repeat which included the EcoRI GAATTC restriction sequence.

Animals↗
PubMed1979

Erythrocyte spectrofluorometric abnormalities in Duchenne patients and carriers. A new approach to carrier detection.

Duchenne muscular dystrophy (DMD) is a disorder whose pathogenesis is attributed, according to the most recent theories, to generalized membrane abnormalities, including red cell membrane. The study of erythrocyte ghosts in patients affected by DMD showed alterations in ion transport and in various enzymatic activities. Employing a spectrofluorometric method using 1-anilino-8-naphthalene sufonate (1.8-ANS) we have tried to characterize the erythrocyte ghosts of DMD patients, definite DMD carriers and normal controls, matched for age and sex. We found an increase of membrane polarity in DMD and definite DMD-carrier erythrocyte ghosts. Using this new method we were able to: - confirm by means of a different technique the previous observations of many authors on erythrocyte ghost alterations in DMD - find a new technique useful in detecting the DMD carriers. It is noteworthy that in such a way the detection rate of definite DMD carriers was higher than with the CPK test.

Adult↗
PubMed1979

Employment of bis-intercalating dyes for the "in situ" study of DNA composition.

Spectrofluorometric characteristics of DNA-RO4 complexes have been studied in order to evaluate the possibility of employment of RO4 (a bis-intercalating dye) for the determination of the DNA base composition. The results have shown the usefulness of this compound for DNA with AT percentage between 30% and 60%. RO4 has been also applied to the study of the chromosome banding mechanism.

Aminoacridines↗
PubMed1978

Low temperature microspectrofluorometry: design of a 'cold chamber'.

Low temperature microspectrofluorometry allows an improvement of spectral resolution and an increase of fluorescence intensity. Suppression of fluorescence fading, or at least a marked reduction, is also obtained. A cooling chamber for microspectrofluorometric measurement is described which allows the cooling, under a microscope, of a biological sample down to liquid nitrogen temperature. Objectives with numerical apertures better than 1.0 and a magnification power up to 100X can be used. Low temperature measurements on a histological sample are presented and discussed.

Bacillus cereus↗
PubMed1977

Cytofluorometric quantification of the activity and reaction kinetics of acid phosphatase.

This paper describes how fluorogenic substrates derived from naphthol AS can be used for the microscopic demonstration and cytofluorometric quantification of the activity and reaction kinetics of acid phosphatase in single living cells. A special study has been made of acid naphthol AS-BI phosphatase. However, the method can be extended to other hydrolytic enzymes. The method is sensitive and accurate because: quantification of very low enzyme activity is possible; the reaction kinetics can be evaluated with a good degree of precision inasmuch as the initial reaction velocity is derived over short times; there is an absence of distributional error; and the errors due to extra-cellular diffusion of the hydrolysed substrate, to photodecomposition, and to autofluorescence can be contained within very narrow limits. The procedures for determining enzyme activity and reaction kinetics, and the instrumental characteristics and devices required for carrying out these measurements, are described. Some possible applications are indicated.

Acid Phosphatase↗
PubMed1975

An electronic device for the automatic correction of fluorescence emission spectra.

An electronic device is described for the automatic correction of fluorescence emission spectra obtained by digital microspectrofluorometry based on multichannel scaling and single photon detection as described previously. This device consists of: (a) an arithmetic unit for the correction of the spectral values and for the curve integration processes; (b) a circuit that operates directly on data in the memory of the multi-channel analyser by subtracting from then a pre-established value corresponding to the background; and (c) an averaging unit for calculating a mean for the spectral value.

Electronics↗
PubMedDate not supplied

Topoisomerase II alpha and beta in human tumor cells grown in vitro and in vivo.

The cellular content and the cell-cycle distribution of the 170 kD- and 180 kD-isoforms of DNA topoisomerase II were investigated in human tumor cells with specific monoclonal antibodies and by immunofluorescent detection with flow cytometry. Levels of topo II alpha were almost three-fold higher than the beta-isozyme in exponentially growing cells in vitro. In contrast, topo II alpha but not beta, was markedly reduced in plateau-phase cells. Tumor cells from surgical biopsies, mainly in G0/G1 phase, exhibited a 95% beta- versus 5% alpha-isoform expression. These results support the hypothesis that topo II alpha is mainly related to DNA synthesis, and topo II beta to DNA transcription.

Antibodies, Monoclonal↗