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Biomedical subjects

G Mazzini

Publications and source records attributed to G Mazzini.

At least 91 records · Page 5Linked to original sources
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

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

Cytofluorimetric evaluation of DNA ploidy in lung cancer: a bronchoscopic study.

The study of the biological characteristics of lung cancer is gaining more and more interest both because of their potential role as prognostic indicators and for therapeutic reasons. The DNA content estimated by flow cytometry in surgical samples of non-small cell lung cancer (NSCLC) has already been demonstrated to be correlated with survival in these patients. From July 1990 to February 1992 we analyzed the DNA distribution of bronchoscopic biopsies from 88 patients with lung cancer (18 small cell lung cancer, SCLC, and 68 NSCLC, two unspecified histology). Twenty-eight tumors (34.6%) had a diploid DNA distribution, while 53 were aneuploid (65.4%). A correlation was found between DNA ploidy and survival. Evaluation of the DNA content in bronchoscopic samples in a large series of patients could determine the role of this analysis prior to surgery in NSCLC and its value as a marker with respect to prognosis and response to therapy in SCLC.

Aged↗
PubMedDate not supplied

Establishment and characterization of two cell lines derived from human glioblastoma multiforme.

We established and characterized two cell lines derived from glioblastoma multiforme. Both cell lines exhibited tumor cell morphology and growth kinetics and showed variable expression of glial fibrillary acidic protein (GFAP), S-100, fibronectin and vimentin. Cytofluorimetrical analysis of tumor samples showed a diploid DNA distribution, whereas permanent culture cells evolved to the hyperdiploid DNA content. Karyotype studies revealed cytogenetical abnormalities described in glial tumors including gain of chromosome 7, loss of chromosome 10 and presence of double minutes (DMs). Enhanced expression of Ha-ras and c-myc genes resulted from high p-21 and p-62 levels. The contemporary presence of TGF-alpha and EGF-Rc transcripts suggested an autocrine mechanism in the cell lines growth.

Cell Division↗
PubMedDate not supplied

Cell cycle-related proteins and flow cytometry.

Several nuclear and surface proteins are expressed in varying amounts in the different phases of the cell cycle. For some of them the coding gene is not known and changes in their expression could simply be secondary to changes in the proliferative activity of the population. Other proteins are oncogene products, probably having a direct regulatory function in cell proliferation, differentiation and malignant transformation. Studying these proteins may both permit a better understanding of the mechanisms regulating proliferation and differentiation and provide kinetic parameters for describing the cell cycle. Based on antibodies against these proteins, bivariate flow cytometry (FCM) is able to quantitate their expression simultaneously with DNA distribution. This allows protein expression to be related precisely with each cell cycle phase in populations having different proliferative activity. Further advantages of bivariate FCM are that few cells are required for the analysis and the percentage of cells expressing the (onco) gene product can be determined. Several cellular proteins have been investigated with bivariate FCM, and the data are reviewed. Some proteins not coded by oncogenes (such as cyclin, the Ki-67 reactive antigen and DNA polymerase alpha) are expressed in cycling, but not in G0 cells and are of special interest for the kineticist, since they could identify cells which are able to initiate DNA synthesis, i.e. those representing the "growth fraction" of the population. Statin, on the contrary, is apparently expressed only in G0 cells. The expression of some proteins coded by oncogenes, such as p53 and the c-myc product is high in proliferating G1 cells and decreases with differentiation. The expression of the c-ras product is not strictly related to cell cycle phases and increases with differentiation. Technical improvements (allowing, for example, the monitoring of the changes in protein expression following the microinjection of a protein-blocking substance into the cells and the inclusion of phenotype markers into the analysis) will expand the role of bivariate FCM for these research works.

Animals↗
PubMedDate not supplied

Bone marrow morphology and proliferative activity in acquired immunodeficiency syndrome.

Peripheral cytopenia has been reported in a number of patients with the acquired immunodeficiency syndrome (AIDS), but the mechanism of bone marrow (BM) failure is unclear. We have examined the BM morphology and cytokinetics of 16 untreated HIV-positive patients whose clinical condition ranged from asymptomatic (stage 1 WR and II CDC classifications) to overt AIDS (stage 6 WR and IV CDC classifications). BM aspirates and iliac crest threphine biopsies were obtained for myelogram and histologic examination, as well as for propidium iodide flow cytometric (FMC) DNA analysis. FCM data were compared with those from the BM of patients with solid tumors without BM involvement. Four patients had normal peripheral blood counts, 2 were anemic, 2 had granulocytopenia, 2 thrombocytopenia, 4 bicytopenia and 2 pancytopenia. BM cellularity was normal or increased, but only 2/16 patients had normal BM morphology. Ten patients had atypical lymphoid aggregates, relative plasmacytosis and eosinophilia, and 4 had typical myelodysplastic changes. There was no correlation between morphology and WR or CDC grade. The mean proliferative fraction (i.e. the percentage of cells in the S phase of the cell cycle) of the HIV-positive patients was 11% (range 5.5-18.3%). The mean value for the control patients was 15.1% (range 7.7-26.9%) (p less than 0.05). All patients had modal diploid DNA content without aneuploid clones. These data suggest that the mechanism of BM failure in HIV-positive patients lies in a reduced proliferative activity whose exact cause is still unclear.

Acquired Immunodeficiency Syndrome↗
PubMedDate not supplied

Simultaneous detection of cellular ras p21 oncogene product and DNA content by two-parameter flow cytometry.

The rapid identification of the expression of oncogene products in specific cell types could be useful to investigate normal and malignant cell proliferation. We have developed a sensitive fixation - permeabilization technique (with 70% ethanol and 0.01% Triton x 100) for the detection of p21 ras oncoprotein and DNA content. Cell suspensions with negligible cell clumping, bright specific immunofluorescent staining were obtained with this method. Bivariate flow cytometry was then used to quantitate simultaneously the distribution of anti p21 ras oncoprotein (with a specific FITC-labeled antibody) and of total DNA (with propidium iodide). The study was carried out in human leukemic cell lines HL-60 and K562, human breast carcinoma cell line MCF-7 and fresh neoplastic cells from human acute leukemia. The p21 ras oncoprotein was found in all phases of cell cycle. The degree of its expression, however, varied widely in diploid (C0/G1) cells from different samples, which could be related to differences in the relative proportion of G0 and G1 cells. Compared to the conventional gel electrophoretic technique, the use of bivariate FCM is feasible, fast, requires fewer cells per sample (2 x 10(6] and allows both the ras oncogene expression in intact cell populations as well as its relationship with cell cycle phases to be studied.

Cell Cycle↗