Search PubMed⌕ Search

Biomedical subjects

M Stefanini

Publications and source records attributed to M Stefanini.

At least 145 records · Page 8Linked to original sources
PubMed1980

Surface interaction in vitro between Sertoli cells and germ cells at different stages of spermatogenesis.

The presence of surface-recognition mechanisms between somatic and germ cells of the seminiferous epithelium has been studied in the rat by an assay in vitro based on the ability of homogeneous populations of spermatogenic cells, at specific differentiative stages, to adhere to monolayers of cultured Sertoli cells. The results show that germ cells adhere specifically to Sertoli cells and that the adhesion is dependent on the differentiative stage of the germ cells. Pachytene spermatocytes show the highest ability to adhere and form typical junctional specializations with the underlying Sertoli cells, while round spermatids adhere much less to the substrate. The possible regulative role of a somatic cell-germ interaction is discussed.

Animals↗
PubMed1980

DNA repair in nuclei isolated from HeLa cells.

We have studied the DNA repair synthesis in HeLa cell isolated nuclei in presence of aphidicolin, which selectively inhibits DNA polymerase alpha but not DNA polymerases beta and gamma. The drug strongly depresses the DNA synthesis rate both in vivo and in the subcellular system but seems not to interfere with DNA repair. The enhancement in nucleotide incorporation by isolated nuclei after UV-irradiation is observed only in the presence of ATP.

Adenosine Triphosphate↗
PubMed1980

Differences in the levels of UV repair and in clinical symptoms in two sibs affected by xeroderma pigmentosum.

UV-repair activity was studied in two sibs affected by XP showing different clinical symptoms. Complementation studies indicated that both patients fit into complementation group A. The levels of UV-induced 3H-thymidine incorporation, in fibroblasts and in lymphocytes, are different in the two patients: residual level of repair DNA synthesis in the sister is higher than in the brother. In one of the cell samples analyzed UDS analysis showed that in the sister a low proportion of cells with normal repair synthesis is present.

Adolescent↗
PubMed1980

Transient deficiency of antihemophilic factor (AHF) procoagulant and AHF-like antigen during administration of tetracycline.

A 35-year old woman showed a transient reduction in level of both moieties of antihemophilic factor (AHF; factor VIII, AHG), following the accidental administration of oral tetracycline. This effect could be reproduced under controlled conditions. No anti-AHF antibodies nor antibodies against tetracycline could be demonstrated. It is suspected that the antibiotic temporarily suppressed the biosynthesis of the AHF procoagulant and AHF-like antigen.

Adult↗
PubMed1979

UV-induced DNA repair in hairy cell leukaemia patients.

We analysed by liquid scintillation counting and by autoradiography the DNA repair synthesis induced by UV irradiation in mononucleated cells from peripheral blood of 'hairy cell leukaemia' patients. In 9 out of 12 patients the repair activity values obtained in repeated assays were found to be significantly lower than those of healthy donors.

Adult↗
PubMed1979

Morphological characteristics of male germ cells of rats in contact with Sertoli cells in vitro.

Fragments of seminiferous epithelium were prepared from 3-week-old rats. Although the Sertoli cells formed a monolayer, germ cells (spermatogonia and early spermatocytes) remained in association with them and were of normal ultrastructural appearance. Germ cells became completely separated from Sertoli cells after 3 weeks of culture in a chemically defined medium. The contact areas between Sertoli and germ cells were characterized by desmosome-like junctions while those between germ cells appeared to be pentalaminar.

Animals↗
PubMed1978

DNA polymerases alpha beta and gamma in inherited diseases affecting DNA repair.

Fibroblasts derived from patients with diseases affecting DNA repair processes, such as Xeroderma Pigmentosum (classical and variant), Fanconi's anemia, Bloom's syndrome, Ataxia Telangiectasica, Progeria and Werner's syndrome, were assayed for the three DNA polymerases. The specific activities of these enzymes were found within the limits observed in normal human fibroblasts. Also the sedimentation properties of the three polymerases were unaltered.

Anemia, Aplastic↗
PubMed1978

Gaisböck's syndrome: its hematologic, biochemical and hormonal parameters.

The syndrome of plethora without splenomegaly, leukocytosis, or thrombocytosis was described by Gaisböck in 1905. It was reevaluated in 25 patients through the study of numerous hematologic and biochemical parameters. Statistically significant findings included mild obesity; elevation of blood pressure (especially diastolic); decrease in plasma volume with relative increase in red cell count, hemoglobin, hematocrit, viscosity of blood, elevation of plasma proteins, serum cholesterol, triglycerides, uric acid, and plasma renin; and increased excretion of urinary sodium. The reduction in plasma volume seemed related to the elevation of the diastolic blood pressure, and favorable through temporary therapeutic results were produced by some antihypertensive agents. The elevation of serum cholesterol, triglycerides, and uric acid, the increased blood viscosity, and the elevated plasma renin were reminescent of the biochemical changes observed in some instances of hypertension and atherosclerotic disease. They may explain why patients with the Gaisböck's syndrome belong to the high risk group of hypertensive individuals who often develop cardiovascular complications. While its long-term effects remain to be evaluated, treatment with nondiuretic antihypertensive drugs may help reduce the incidence of these complications.

Adult↗
PubMed1978

Determination of serum myoglobin level after death in the diagnosis of sudden coronary artery occlusion.

Serum myoglobin was determined by radioimmunoassay in 20 cases of sudden and unexpected death resulting from acute coronary occlusion. There was consistent elevation of myoglobin 2 h after death, with peaking at 3 h. No comparable elevation of serum myoglobin level was noted in patients who had succumbed to pulmonary embolism, ruptured aortic aneurysm, or subarachnoid or intracerebral hemorrhage. Thus, determination of serum myoglobin seems useful in confirming or establishing acute coronary occlusion as the cause of sudden and unexpected death.

Coronary Disease↗
PubMed1977

Levels of DNA polymerase-alpha and beta in normal and xeroderma pigmentosum fibroblasts.

We have determined the levels of DNA-polymerases-alpha and-beta in fibroblasts obtained from normal subjects and from patients with Xeroderma Pigmentosum (XP) belonging to three different complementation groups and to the variant form. The assays have been performed in crude extracts and after fractionation on sucrose gradients. The levels of alpha and beta-polymerases in the different cases of XP were found to lie within the same range as the control values, and no correlation was found with the severity of the symptoms. The sedimentation coefficients of the two polymerases from all the pathological lines were identical to those of the normal fibroblasts.

Cells, Cultured↗
PubMed1976

Incorporation of (3H)thymidine stimulated by ultraviolet radiation into human fibroblast cultures.

We studied DNA repair synthesis after ultraviolet irradiation in human fibroblasts cultured in vitro by measuring the ultraviolet-stimulated incorporation of [3H]thymidine into cells in which the semi-conservative DNA replication was inhibited by hydroxyurea. Experiments performed with five fibroblasts lines derived from healthy donors showed a relatively fast initial process ( that is completed within 1 h for 100 erg/mm2 and within 2 h for 500 erg/mm2) and a subsequent slower process, evident between 2 and 6 h after irradiation. The repair capacity of normal cells is expressed by the difference between the values of incorporation (in presence of hydroxyurea) of irradiated and control cells. The pattern of repair was similar in all five cell lines: repair capacity was positive and the amount of repair synthesis increased with incubation time after UV irratiation. Similar experiments were performed with fibroblasts derived from five patients with the classical xeroderma pigmentosum (XP) and from one patient with the De Sanctis-Cacchione syndrome. Normal and XP cells could be distinguished according to whether they displayed a positive or negative value of repair synthesis and/or according to the degree of the slope of the repair synthesis curve as a function of the incubation time after irradiation. We conclude that the technique used in our experiments can demonstrate in a rapid and simple way a defect in the repair capacity in fibroblast cultures; the data are in good agreement with those obtained in the same XP cell lines by other authors [9], who have measured unscheduled DNA synthesis in autoradiographs and repair replication after addition of BUdR.

Cells, Cultured↗
PubMed1976

Variations of DNA polymerase-alpha and -beta during prolonged stimulation of human lymphocytes.

Stimulation of human lymphocytes with phytohemagglutinin is known to induce an increase in overall DNA polymerase activity (DNA nucleotidyltransferase; deoxynucleosidetriphosphate:DNA deoxynucleotidyltransferase, EC 2.7.7.7). Previous work [Pedrali Noy, G., Dalprà, L. Pedrini, A. M., Ciarrocchi, G., Giulotto, E., Nuzzo, F. & Falaschi, A. (1974) Nucleic Acids Res. 1, 1183] has shown that two subsequent waves of induction of DNA polymerase can be observed in this system; a first wave occurs in parallel with the increase in DNA replication rate; a second one occurs when the DNA synthesis rate is returned to minimal levels; the second peak is parallel to a maximum in DNA ligase and DNase levels. In the present work we have measured the levels of the DNA polymerases-alpha and -beta in phytohemagglutinin-stimulated lymphocytes during a 12-day period; both enzymes are present at detectable levels at time zero; in correspondence to the peak of DNA synthesis rate (between the fourth and fifth day) a peak of DNA polymerase-alpha is observed, increasing by a factor of approximately 20-fold over the zero time value; subsequently, the level of DNA polymerase-alpha decreases in parallel with DNA synthesis rate. The DNA polymerase-beta is also increased in correspondence to the peak in DNA synthesis rate, but reaches its maximum at later times, between the eighth and tenth day of incubation. The capacity of stimulated lymphocytes to perform repair synthesis following UV damage was measured in the same cells used for the enzyme activity determinations; this capacity also shows two maxima: a first one correlated with the peak in DNA replication rate, and a second one correlated with the peak of DNA polymerase-beta. These data suggest a certain tendency to the specialization of functions in human cell DNA polymerases; the alpha-enzyme seems mainly correlated with DNA replication, whereas the beta-enzyme seems more correlated with the ability of the cell to perform repair type synthesis.

DNA Nucleotidyltransferases↗
PubMed1976

Detection of aneuploid cells in fibroblast cultures from the father of two trisomy 21 patients.

Karyotype analysis was performed on successive cultures of fibroblasts from the parents of two trisomic 21 patients. Starting from the 7th passage in the father cultures an aneuploid clone showing an extra E-like chromosome was found, which eventually overgrew the cell population. The significance of this cytogenetic finding is discussed in relation to the recurrence of the trisomy in the family.

Aneuploidy↗