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Biomedical subjects

M Durante

Publications and source records attributed to M Durante.

At least 109 records · Page 6Linked to original sources
PubMed1981

Immunological studies of aging. Decreased production of and response to T cell growth factor by lymphocytes from aged humans.

Human lymphocytes from elderly and young donors were cultured with phytohemagglutinin (PHA) or concanavalin A. Cultures from old donors produced less T cell growth factor (TCGF) and incorporated less tritiated thymidine (3H-Tdr) than did similar cultures from young donors in the presence of either mitogen. Furthermore, the response of lymphocytes from elderly donors to TCGF was impaired. Thus, PHA-activated T cells from aged donors showed no increase tritiated thymidine incorporation when incubated with exogenous human TCGF. In contrast, addition of exogenous human TCGF to PHA-activated peripheral blood leukocytes from younger individuals increased tritiated thymidine incorporation by 30-50%. The impaired response to TCGF was associated with decreased binding of TCGF by PHA-activated cells from old donors. TCGF production or responsiveness was not associated with the presence of "suppressor" activity in elderly T cell preparations. These studies suggest a possible molecular mechanism for the impaired proliferative response of elderly human T cells. These data lend support to the hypothesis that defects in the capacity to either produce or respond to TCGF may be a fundamental cause of immune deficiency.

Adult↗
PubMed1977

Cytological localization of the genes for the four classes of ribosomal RNA (25S, 18S, 5.8S and 5S) in polytene chromosomes of Phaseolus coccineus.

Homologous tritiated 25S, 18S and 5.8S rRNAs were used separately for in situ hybridization to the polytene chromosomes of the embryo suspensor cells of phaseolus coccineus. Hybridization occurred at the same chromosomal sites which were labeled in previous in situ hybridization experiments with 25 + 18S rRNAs in the same material (Avanzi et al., 1972), namely: nucleolus organizing system (satellite, nucleolar constriction and organizer) of chromosome pairs I (S1) and V (S2), proximal heterochromatic segment of the long arm of chromosome pair I, and terminal heterochromatic segment of chromosome pair II. Competition hybridization experiments confirmed for P. coccineus the high sequence homology between 25S and 18S rRNA already known for other plants. Homologous 125I-5S rRNA was found to hybridize to three sites in the polytene chromosomes of P. coccineus: the proximal heterochromatic segment in the long arm of chromosome pair I (which also bears the sequences complementary to 25S, 18S and 5.8S RNAs), most of the proximal heterochromatic segment plus a small portion of adjoining euchromatin in the long arm of chromosome pair VI and the large intercalary heterochromatic segment in the same chromosome pair. Simultaneous labeling of the two 5S RNA sites in chromosome VI was quite rare (3%), the rule being labelling of one site to the exclusion of the other, with a labeling frequency of 43.7% and 53.3% for sites no. 1 and no. 2 respectively. These results are interpreted as being due to differential hybridizability of chromosomal sites such as described in other materials.

Chromosome Mapping↗
PubMedDate not supplied

Modulation of membrane potential in algal cells by temperature gradients. A thermodynamic approach.

The aim of the present study is to ascertain whether transmembrane temperature gradients couple with transport of electric charge in living cells of Valonia utricularis and eventually measure the thermodynamic coupling coefficient (s). Simple experimental procedures are described that allow generation of temperature gradients of predetermined sense and intensity across the cell membrane. Simultaneous measurement of the potential difference is ensured by standard electrophysiological methods. The mathematical expressions that allow quantitative treatment of experimental results are indicated in the article and are based on standard nonequilibrium thermodynamic and electrophysiological formalism. The value of the coupling coefficient between temperature gradient and flow of electric charge is indicated and concisely discussed in terms of possible mechanisms of ionic membrane transport.

Biological Transport↗
PubMedDate not supplied

Left ventricular mass and heart rate variability in middle-aged and elderly salt-sensitive hypertensive subjects.

Previous reports have shown that in salt-sensitive hypertension a high dietary salt intake can increase sympathetic activity. We evaluated the influence of the autonomic nervous system on myocardial hypertrophy by power spectral analysis of heart rate variability in middle-aged and elderly salt-sensitive hypertensive subjects. We compared autonomic nervous system activity in 32 salt-sensitive hypertensive patients (15 subjects with mean age, 42.4+/-2.4 years and 17 subjects with mean age, 74.6+/-1.6 years) and 20 age-matched normotensive controls. Power spectral analysis detects four spectral components: total power (TP), high-frequency (HF), low-frequency (LF) and very-low-frequency (VLF) power. In the elderly subjects we found an association between the left ventricular mass index (LVMI) and the following variables: very-low frequency (P<0.0001), 24-h urinary sodium excretion (P<0.0001) and diastolic blood pressure (DBP) (P<0.0001). In contrast, in middle-aged subjects we found a significant association between the LVMI and LF (P<0.001). In middle-aged, but not in elderly salt-sensitive hypertensive subjects, increased sympathetic activity correlated with the LVMI (P<0.0001). Our findings suggest an association between sympathetic hyperactivity and the LVMI in middle-aged subjects with salt-sensitive hypertension.

Journal Article↗
PubMedDate not supplied

Differences in membrane order between C3H 10 T1/2 cells and their transformed counterparts as measured by EPR.

Membrane order of mouse embryo fibroblasts and their ionizing radiation and chemically transformed counterparts was investigated using EPR spectroscopy after labeling the membrane of the cells with the fatty acid spin label, 5-nitroxy stearic acid. The EPR spectra were recorded at temperatures ranging from 18 to 38 degrees C for both control and transformed cells. The distance between the outer hyperfine splitting (2T' parallel), which is used as indicator of membrane order, varies in these two cell types. Below 28 degrees C. 2T' parallel is higher in transformed fibroblasts than in normal cells, whereas above this temperature membrane order is the same. Lipid analysis as carried out by the measurement of the cholesterol/membrane proteins and sphingomyelin/lecithin ratios, showed no difference in the amounts of the main membrane rigidifiers. These findings suggest that cell transformation of mouse fibroblasts induced by radiation or chemicals may produce alterations in the cell membrane, as evidenced by variations in its order at low temperature. These measured differences are presumably not attributable to its fatty acids composition but to its glycoproteins content, since changes in membrane rigidifiers were not observed between normal and transformed cells.

Animals↗
PubMedDate not supplied

Efficacy and acceptability of transdermal estradiol in the treatment of postmenopausal bone loss.

In order to assess the effects and acceptability of transdermal estradiol on the prevention of the loss of bone mass, the Authors administered transdermal estradiol (ETTS 50 mcgr/day) for 3 weeks and, cyclically, medroxyprogesterone 10/mg/day from day 10 to day 21 of each cycle for 12 months, to 20 operated patients for bilateral ovariectomy. Primary markers of the bone turnover (hydroxyproline urinary, osteocalcin, PTH) were estimated before therapy and after 3, 6, 9, 12 months. The BMD was evaluated before therapy and after 6 and 12 months. Our study clearly shows that the transdermal administration of estradiol prevents the postmenopausal bone loss, also in postmenopausal women at higher risk of developing osteoporosis as those evaluated in our study.

Administration, Cutaneous↗
PubMedDate not supplied

[Use of levosimendan after cardiac arrest by ventricular fibrillation: a case report].

We describe the case of a patient admitted in intensive care, after cardiac arrest by ventricular fibrillation treated by electrical defibrillation, that showed a serious deficit of the cardiac index and increase of the systemic vascular resistances. The patient was treated by levosimendan (Simdax): a starter dose of 12 microg/Kg in ten minutes and then a continuous perfusion of 0.1 microg/Kg/min. for 24 hours. He had a continuous amelioration of the clinical conditions and of the hemodynamics parameters. In the fifth day the patient was transferred to the Cardiology department and after 20 days he was discharged from hospital.

Anti-Arrhythmia Agents↗