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Biomedical subjects

G Bottiroli

Publications and source records attributed to G Bottiroli.

86 records · Page 5Linked to original sources
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

Effects of DTIC, DM-COOK and ICRF-159 on the number of circulating Lewis lung carcinoma cells detected by flow cytometry.

Circulating tumor cells can be detected by means of flow cytometry in the blood of mice bearing i.m. Lewis lung carcinoma. This technique can be applied in the case of aneuploid tumors and does not require either concentration of nucleated cells or other processing of the blood samples. It offers the advantages of simplicity and speed and allows quantitative measurement of the number of circulating tumor cells. It can be applied to the study of the effects of drug treatment on the number of circulating tumor cells, for those drugs which do not cause alterations in the nuclear DNA content of normal diploid blood cells. The number of circulating tumor cells determined by flow cytometry is markedly reduced by treatment with ICRF-159, by dimethyltriazene DM-COOK, and also by its clinically used analog, DTIC.

Animals↗
PubMedDate not supplied

Influence of daunorubicin on membrane permeability properties: detection by means of intracellular accumulation and efflux of fluorescein.

The influence of daunorubicin (DNR) on membrane permeability properties was assessed by studying the ability of living HeLa cells to exhibit fluorochromasia; that is, to take up a fluorogenic substrate and retain the fluorescent compound obtained by enzymatic reaction. The intracellular accumulation of the fluorescent product as well as its release by the cells may be considered indicators of the permeability properties, since both processes are mediated by the cell membrane. The influence of the drug on the accumulation and on the efflux of fluorescein, obtained intracellularly from the hydrolysis of fluorescein diacetate (FDA), was evaluated, after DNR treatment, by measuring the fluorescence intensity of the product in single living cells by flow cytometry. The results showed that DNR, up to a concentration of 5 X 10(-6) M, did not significantly affect the accumulation of fluorescein. On the contrary, the efflux was strongly inhibited. A comparative study of the influence of drugs with known action mechanism was performed with the membrane-active compound hydrocortisone (HC) and with the metabolic inhibitor KCN. The results obtained indicate that DNR significantly affects membrane permeability properties and that its influence is similar to that exerted by metabolic inhibitors.

Cell Membrane Permeability↗
PubMedDate not supplied

Fluorescence energy transfer shows that various physical and chemical treatments of human sperm induce unpacking of chromatin.

Fluorescence resonance energy transfer (FRET) was used to study the changes which human sperm chromatin went through after various physical and chemical treatments. This technique showed a dilatation of the spatial relationship among chromatin liner arrays, with UV and DNAse among the treatments that gave rise to the highest increase. FRET image analysis showed that the chromatin linear arrays after treatment reach a spatial disarrangement similar to that brought about by sperm decondensation. Comparison of these results with the ability of human treated sperm to form pronuclei after microinjection into hamster eggs, suggests that the highly condensed spatial organization of sperm chromatin arrays may not be a necessary prerequisite for pronucleus formation.

Animals↗
PubMedDate not supplied

The Golgi apparatus is a primary site of intracellular damage after photosensitization with Rose Bengal acetate.

The aim of the present investigation was to elucidate whether the Golgi apparatus undergoes photodamage following administration of the fluorogenic substrates Rose Bengal acetate (RBAc) and irradiation at the appropriate wavelength. Human HeLa cells were treated in culture and the changes in the organization of the Golgi apparatus were studied using fluorescence confocal microscopy and electron microscopy, after immunocytochemical labeling. To see whether the cytoskeletal components primarily involved in vesicle traffic (i.e., microtubules) might also be affected, experiments of tubulin immunolabeling were performed. After treatment with RBAc and irradiation, cells were allowed to grow in drug-free medium for different times. 24 hr after irradiation, the cisternae of the Golgi apparatus became packed, and after 48-72 hr they appeared more fragmented and scattered throughout the cytoplasm; these changes in the organization of the Golgi cisternae were confirmed at electron microscopy. Interestingly enough, apoptosis was found to occur especially 48-72 h after irradiation, and apoptotic cells exhibited a dramatic fragmentation of the Golgi membranes. The immunolabeling with anti-tubulin antibody showed that microtubules were also affected by irradiation in RBAc-treated cells.

Fluorescent Dyes↗
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↗
PubMedDate not supplied

Metabolic energy availability and proliferative activity in adriamycin-treated cells.

Metabolic energy availability and proliferative activity were studied in HeLa cells treated with Adriamycin (Adr). Conditions (ID50) that induced growth delay, without significant cell lethality, did not appreciably alter ATP content, over 72 hours after treatment. Energy-dependent membrane permeability properties, assessed with the vital dye fluorescein, were similarly unaffected. The cytostatic effect was confirmed by the incorporation rate of 3H-thymidine and 14C-leucine, and by flow cytometric analysis of cell cycle progression. Early depletion in cellular ATP occurred when Adr induced an evident cytocidal effect.

Adenosine Triphosphate↗
PubMedDate not supplied

Erythrocyte spectrofluorometric abnormalities in myotonic dystrophy during "in vitro" aging.

The possibility in Myotonic dystrophy (MyD) that a decreased ATP utilization by the membrane may produce modifications in glycoprotein structure and/or in the supramolecular arrangement of some membrane proteins was investigated in human erythrocytes: a) by determining the membrane sialic acid content and the cellular ATP concentration in eight cases of MyD; b) by evaluating the stability of the membrane glycoprotein structure by in vitro ageing experiments; c) by testing the presence of high molecular weight aggregates of proteins on the membrane; d) by evaluating the physico-chemical properties of the membrane by 1-anilino 8-naftalensulfonate as a fluorescent probe. Our evidence suggests that ATP concentration and membrane sialic acid content are within normal values. Only in two cases did a decreased stability of membrane glycoproteins occur while the supramolecular assembly of membrane proteins could be considered as normal. The fluorescent probe behavior after in vitro aging was indicative of a decreased polarity of its micro-environment.

Adenosine Triphosphate↗
PubMedDate not supplied

Free radical-dependent DNA lesions are involved in the delayed cardiotoxicity induced by adriamycin in the rat.

The role of free radicals in the genesis of adriamycin (ADR)-induced delayed cardiotoxicity and the cardioprotective effects of the spin trap N-tert-butyl-alpha-phenylnitrone (PBN) were investigated in an in vivo rat model. As ADR and free radicals are no longer present in the myocardium by the time the delayed effects of the drug become apparent, ADR has been proposed to act by causing early radical-dependent DNA lesions, resulting in impaired synthesis of critical target proteins. DNA lesions were detected 10 days after ADR treatment (3X3 mg/kg i.v.) and were still present at the time of onset of the delayed cardiomyopathy. PBN, administered by a slow-release osmotic pump to maintain constant plasma levels throughout the time of persistence of ADR in the myocardium (approximately 2 weeks), prevented the development of DNA lesions, as well as the late contractile and electrical impairment induced by the anthracycline, thus supporting the hypothesis that free radicals play a causal role in both phenomena.

Animals↗
PubMedDate not supplied

The spin trap alpha-phenyl-tert-butyl nitrone protects against myelotoxicity and cardiotoxicity of adriamycin while preserving the cytotoxic activity.

The possibility of preventing the myelo- and cardiotoxicity of adriamycin (ADR), was explored in in vivo experiments in the rat. Assuming that free radicals play a key role in the ADR organotoxicity, a new anti-radical approach was set up by administering a spin trapping compound (PBN) which is taken up by the cells and specifically interacts with radicals. ADR was given i.v., 3 mg/kg every 3rd day for 3 times. PBN was continuously administered throughout the persistence time of ADR in myocardium (15 days). Serial ECG and leukocyte counting were performed during 10 weeks, then hearts were isolated and Langendorff-perfused; functional parameters (heart rate, contractility, coronary flow) were evaluated. PBN improved ECG and prevented the myelotoxicity, while functional parameters were not significantly different from those of control. Cytotoxicity was evaluated in vitro in 3 different human tumour cell lines; PBN did not modify the cytotoxicity of ADR, thus excluding a free radical involvement in this activity. The present results suggest that a proper administration schedule of spin traps might be a promising approach for improving the therapeutic index of ADR.

Animals↗