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Biomedical subjects

G Pozzi

Publications and source records attributed to G Pozzi.

35 records · Page 2Linked to original sources
PubMed1987

Cellular uptake and metabolic reduction of pentavalent to trivalent arsenic as determinants of cytotoxicity and morphological transformation.

Cytotoxicity, morphological neoplastic transformation, cellular uptake and metabolic reduction were determined in BALB/3T3 Cl A31-1-1 cells for trivalent arsenic (sodium arsenite, As3+) and for pentavalent arsenic (sodium arsenate, As5+). The levels of cellular uptake of 73As-labelled sodium arsenite and arsenate were dose-dependent and highest in the first hour. At equimolar concentration (3 X 10(-6) M), cellular uptake was 4-fold higher for As3+ than for As5+. Cytotoxicity was higher for As3+ than for As5+, but when correlated to total As cell burden it showed no significant difference for the two forms. Morphological transformation focus assays showed transforming activity for both As3+ and As5+, with relative transformation frequencies also of approximately 4:1. Recovery from the cytosol after exposure for 1-24 h was greater than 90% for either form of absorbed As. Exposure to As3+ yielded 100% as As3+ in cytosol, but exposure to As5+ yielded greater than 70% as As3+, showing a high rate of intracellular metabolic reduction. No methylated metabolites were detected by ion-exchange chromatography. After 24-h incubation in cell-free medium, oxidation of As3+ to As5+ occurred up to 30% of the dose, but incubation in the presence of cells lowered the oxidation level to 4%. As5+ was recovered unchanged from cell-free medium (24-h incubation), but in the presence of the cells it yielded up to 5% as As3+ within 24 h and the cumulative release of As3+ by cells exposed to As5+ was dose-dependent. Glutathione depletion by diethylmaleate inhibited reduction of As5+ to As3+ by these cells up to 25% of controls, showing that As5+ reduction is partly dependent on glutathione. These results suggest that As3+ is the form responsible for the cytotoxic and transforming effects, independently of the valence state of the inorganic arsenic in the culture medium.

Animals↗
PubMed1987

Amiodarone lung toxicity: role of pulmonary function tests.

Forty-three patients treated with amiodarone hydrochloride with an average daily dose of 204.7 +/- 79.4 mg/day for a mean period of 37.1 +/- 25.3 months, were studied by clinical examination, chest roentgenograms, pulmonary function tests and blood gas analyses. The habits of cigarette smoking were also recorded and expressed as cigarette pack/years. Pulmonary function tests did not show any differences from control subjects and no correlation was found between exposure to drug and lung function. However, one patient developed abnormalities in the chest X-ray (interstitial type) and a reduction of carbon monoxide diffusion capacity as a possible manifestation of amiodarone lung toxicity. Nine patients (22%) had a 20% decrease from normal in carbon monoxide diffusion capacity and three (7%) had a 15% decrease in total lung capacity. More treated patients had interstitial abnormalities in the chest X-ray (14%) than controls (5.5%). Although pulmonary function test abnormalities could be detected in patients taking amiodarone, they were not usually severe enough to interfere with gas exchange. Our results confirm the rarity of amiodarone lung toxicity when a low dosage is used, and suggest the advisability of periodical monitoring, including clinical examination, chest X-ray and pulmonary function tests in order to detect the earliest signs of amiodarone lung toxicity.

Adult↗
PubMed1986

Transformation as a tool for studying the epidemiology of tet determinants in Streptococcus pneumoniae.

Transformation of pneumococcus was used to detect homology among tetracycline resistance determinants of clinical isolates of Streptococcus pneumoniae. A strain of pneumococcus containing a mutated tet determinant (tet-3), of class M, integrated into the chromosome was used as a recipient in transformation experiments, where donor DNA was from the tetracycline resistant isolates. 34/34 strains appeared to have tet determinants homologous to tet-3 (i.e. tet M). Still using transformation it was possible to determine that the tet-3 transforming activity of DNA from Tn916 and S. pneumoniae BM6001 was contained in a 5 kb HincII fragment. For this purpose a transformation technique where donor DNA was directly taken from low melting point agarose gels was standardized and used.

DNA, Bacterial↗
PubMed1986

Cloning and physical characterization of chromosomal conjugative elements in streptococci.

We used a directed insertion method to introduce a nonreplicating vector plasmid into the large conjugative cat-tet element found in the chromosome of Streptococcus pneumoniae BM6001 and derivatives. To direct insertion preferentially to the conjugative element, we transferred it by conjugation to Streptococcus faecalis and then used DNA from this strain as a source of restriction nuclease fragments for ligation to digests of the vector pVA891, which can replicate in Escherichia coli but not in streptococci. This ligation mix was used to transform pneumococcal cells carrying the cat-tet element, with selection for the erythromycin resistance carried by pVA891. Eight such isolates were found, and transformation and conjugation tests showed that in each case the vector had inserted into the conjugative element, as expected. DNA from these pneumococcal strains generated a variety of E. coli plasmids which provide tools for obtaining a detailed restriction map and for defining other structural features of the streptococcal conjugative element.

Bacterial Proteins↗
PubMed1985

Modes of integration of heterologous plasmid DNA into the chromosome of Streptococcus pneumoniae.

We compared the efficiencies of two different processes that can direct integration of plasmids into chromosomes of recipient cells during transformation. A donor-recipient system was constructed to allow a single donor plasmid to use either flanking homology, involving an apparent double crossover, or the insertion duplication process that has been described as due to a "Campbell-like" single crossover between the chromosome and a circular duplex. The latter process gave 600-fold fewer insertions that did the former, confirming expectations from prior work showing that insertion of heterologous DNA by use of flanking homology is highly efficient. It has some advantages for cloning and mapping purposes and can be exploited once it is recognized.

Chromosomes, Bacterial↗
PubMed1985

Bronchial hyperreactivity and arterial carboxyhemoglobin as detectors of air pollution in Milan: a study on normal subjects.

Research has been carried out in the town area of Milan on 275 subjects. For each patient the following data have been measured: ventilatory profile, aspecific bronchial reactivity, arterial concentration in CO and acid-base balance. The results obtained have been divided into four groups, according to the level of SO2 in the area of residence of the subjects, who have also been studied with reference to the habit of smoking. The data obtained have shown (1) an alteration of the ventilatory function, with decrease of oxygen tension in arterial blood in all subjects. (2) Increase of bronchial irritability and CO concentration in arterial blood have been found in these subjects, with rates higher than those established by the WHO (1.5-1.7). (3) The division of our results according to the level of SO2 pollution in the areas of residence of the patients showed the presence, in the most polluted areas of Milan (NE and SW), of higher levels of bronchial irritability and higher CO rates in arterial blood. (4) Cigarette smoking does not seem to play a major role in causing bronchial irritability. It certainly increases CO concentration: smokers have HbCO concentration higher than nonsmokers in all four areas. (5) Air pollution is more important than cigarette smoking in determining CO saturation of blood. Nonsmokers living in the most polluted areas of Milan (NE) show a higher concentration of CO in arterial blood than smokers living in the less polluted areas (SW).

Adult↗
PubMed1979

[Findings on the knowledge of self-examination of the breast].

A research on the degree of knowledge about the problem of breast self-examination was carried out in a group of 500 women in the Out-patients Department of the Cancer Institute in Milan. The women were given a questionnaire to fill up at home and to return at the moment of the medical examination. The analysis of data showed that, though the level of education of the subjects was fairly good, the knowledge and the practise of the periodical self-examination as a method for an early diagnosis was very low. 70% of the women declared to have some knowledge about the method, but only 9% declared to practise it regularly.

Breast↗
PubMed1976

[Studies on the risk factors of arteriosclerosis in a health district region of Lombardy].

Atherosclerosis risk factor, 8,5% two, 2,7% three and 0,6% four.rs have been investigated in 194 males and 135 female, 25 years old. Elevated lipids were found in 7,3% of the sample; "labile" and stable hypertension in 2,7%; diabetes mellitus in 2,7% and overweight in 19%. 19% of the subjects smoked more than 20 cigarettes daily. Prevalence of hyperlipemia and electrocardiographic changes was higher among people in the lower socioeconomic classes. Taking into consideration hyperlipidemia, hypertension, cigarette smoking, overweight and diabetes mellitus as risk factors, 25% exhibited one risk factor, 8.5% two, 2.7% three and 0.6% four.

Adult↗
PubMedDate not supplied

Method and parameters for genetic transformation of Streptococcus sanguis Challis.

A simple procedure for genetic transformation of Streptococcus sanguis Challis was developed and standardized. During the exponential phase of growth, cells became competent while growing as diplococci in broth containing 10% foetal calf serum. High levels of competence were maintained by the cultures for 60 min. Competent cells could be stored frozen without loss of competence for at least three years. Using total chromosomal DNA as donor, the dose-response curve for transformation of a point mutation (streptomycin resistance) showed one-hit kinetics, as the DNA concentration varied from 0.000001 to 10 micrograms/ml. At 10 micrograms/ml, more than 2.2% of the colony-forming units were transformed to streptomycin resistance, while transforming activity remained detectable with 1 pg of DNA/ml. Optimal time of exposure of competent cells to transforming DNA was 30 min. The transformation reaction was inhibited at 0 and 4 degrees C, whereas it occurred efficiently both at 25 and 37 degrees C.

DNA, Bacterial↗
PubMedDate not supplied

Object-orientated DBMS techniques for time-oriented medical record.

In implementing time-orientated medical record (TOMR) management systems, use of a relational model played a big role. Many applications have been developed to extend query and data manipulation languages to temporal aspects of information. Our experience in developing TOMR revealed some deficiencies inside the relational model, such as: (a) abstract data type definition; (b) unified view of data, at a programming level; (c) management of temporal data; (d) management of signals and images. We identified some first topics to face by an object-orientated approach to database design. This paper describes the first steps in designing and implementing a TOMR by an object-orientated DBMS.

Algorithms↗
PubMedDate not supplied

Control of B16 melanoma cells differentiation and proliferation by CuSO4 and vitamin C.

The effects exerted by CuSO4, in the presence or absence of vitamin C, on melanogenesis and proliferation in mouse B16 melanoma cells in culture were analysed either in serum-free (MEM-N2) or in serum-supplemented media. The stimulation or the inhibition of these cellular parameters can be induced, depending on the metal concentration, the presence or absence of vitamin C, the composition of the culture medium and on the type of culture (subconfluent or clonal). Vitamin C toxicity for B16 cells was generally increased in serum-free medium, in clonal cultures, or in the presence of CuSO4.

Ascorbic Acid↗
PubMedDate not supplied

Effects of FeSO4 on B16 melanoma cells differentiation and proliferation.

The effects exerted by FeSO4, in the presence or absence of vitamin C, on melanogenesis and proliferation in mouse B16 melanoma cells in culture were analysed either in serum-free (MEM-N2) or in serum-supplemented media. These cellular parameters can be either stimulated or on the contrary inhibited, depending on the metal concentration, the presence or the absence of vitamin C and serum, and on the type of culture (subconfluent or clonal). Vitamin C toxicity for B16 cells was decreased in the presence of FeSO4.

Animals↗