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Biomedical subjects

G Pagnini

Publications and source records attributed to G Pagnini.

At least 19 recordsLinked to original sources
PubMed2004

Influence of Eulerian and Lagrangian scales on the relative dispersion properties in Lagrangian stochastic models of turbulence.

The influence of Eulerian and Lagrangian scales on the turbulent relative dispersion is investigated through a three-dimensional Eulerian consistent Lagrangian stochastic model. As a general property of this class of models, it is found to depend solely on a parameter beta based on the Kolmogorov constants C(K) and C0. This parameter represents the ratio between the Lagrangian and Eulerian scales and is related to the intrinsic inhomogeneity of the relative dispersion process. In particular, the quantity g*=g/C(0) (where g is the Richardson constant) and the temporal extension of the t(3) regime are found to be strongly dependent on the value adopted for beta.

Journal Article↗
PubMed2000

Modulation of anthracycline activity in canine mammary tumour cells in vitro by medroxyprogesterone acetate.

Failure of chemotherapy with anthracyclines as a result of drug resistance and toxicity is a major problem in the clinical management of neoplasia. The aim of the present study was to evaluate the activity of medroxyprogesterone acetate (MPA) as a chemosensitiser on anthracycline cytotoxicity. The study investigated whether such an effect could be related to an increase in lipid peroxidation, nitric oxide production, membrane fluidity and intracellular anthracycline concentration. The results showed that anthracyclines decreased nitric oxide production but increased membrane viscosity (polarisation constant) and lipid hydroperoxide formation in canine mammary tumour cells. Moreover, it was found that both drug-induced cytotoxicity and membrane viscosity increased in the presence of MPA. Conversely, lipid hydroperoxides decreased in MPA-supplemented cells. Medroxyprogesterone acetate did not show any effect on nitric oxide production. The two anthracyclines used (doxorubicin and idarubicin) showed differential intranuclear accumulation in canine mammary tumour cells, and MPA significantly modified intracellular concentration of anthracyclines.

Animals↗
PubMed1996

The effect of age and sex on the expression of prolactin binding activity in the chicken bursa of Fabricius.

The binding of 125I-labeled prolactin (PRL) to membranes from the bursa of Fabricius of male and female chicks of different ages (15-30-45 and 60 days) was studied. In male chicks the binding was very low in 15 day-old animals and slightly increased in more aged animals. In female chicks the binding was more evident in young animals and decreased in 60 day-old animals. The binding showed a hormonal specificity and Scatchard analysis of the binding revealed the presence of binding sites with low capacity and high affinity. The presence of PRL receptors in the bursa of the chick, a structure that confers immunological competence to birds, gives further support to the involvement of the hormone in the immune processes.

Aging↗
PubMed1996

Effect of cis-diamminedichloroplatinum (II) on rat thymocyte membrane potential.

The effect of cis-diamminedichloroplatinum (II) (cisDDP) on rat thymocytes has been investigated. Changes of anisotropy constant and depolarization of the cell membrane have been determined. The effect of cisDDP on the anisotropy constant has been observed on treated animal thymocytes but not on treated isolated cell membranes. CisDDP inhibits KCl-induced depolarization in isolated rat thymocytes. This inhibiting effect is still present at a concentration as low as 5 microM and it is dose-dependent with a 9.6 microM ED50. CisDDP also boosts the inhibition of the polarization caused by 10 microM tetrodotoxin (TTX) and 10 microM doxorubicin (DOXO). The replacement of Na+ by choline and the inactivation of Ca2+ by EGTA, in the incubation medium, reduces the inhibiting effect of cisDDP on the KCl-induced depolarization. These results suggest that cisDDP induced alterations could be due to the interference of cisDDP with the activity of the ionic channels pertaining to Na+ and Ca2+. This interference is stronger for Na+ channels.

Animals↗
PubMed1988

Regional distribution and species variation of prolactin binding sites in the brain.

The binding of 125I-labeled ovine prolactin (125I-oPRL) to membranes from different brain regions of pigeon, rabbit, rat, pig, calf, horse, and ewe was studied. The hypothalamus from rabbit, pig, horse, and pigeon showed a low but specific binding for 125I-oPRL clearly different from the other brain regions examined (cortex and cerebellum), whereas in the brain from rat, calf, and ewe the binding was very small and quite uniform in the various regions. Also the membranes from choroid plexus of rabbit, pig, calf, and horse showed an evident specific binding for prolactin. The binding of 125I-oPRL to hypothalamus and choroid plexus membranes from rabbit and horse was inhibited in a dose-dependent manner by unlabeled oPRL and hGH but not by many other polypeptide hormones. Scatchard analysis of the binding revealed the presence of binding sites with low capacity and high affinity for ovine ligand.

Animals↗
PubMed1978

[Neuropsychopharmacological effects of TCDD].

It has been found that TCDD (2,3,7,8-tetrachlorodibenzo-p-dioxin), in rats, endoperitoneally or orally administered at dose of 1-10 mcg/kg, provokes irritability, aggressivity and restlessness (increase of spontaneous crossings in the shuttle box). The TCDD does not modify the conditioned avoidance (C.A.) or the conflictual situation. In "vitro" the TCDD stimulates directly the striatal and hypothalamic adenylate cyclase of rat. The TCDD increases the stimulation produced by dopamine on striatal adenylate cyclase. Haloperidol (dopamine antagonist) inhibits the stimulation produced by TCDD. TCDD does not significantly modify the stimulation by hystamine on hypothalamic adenylate cyclase. Cimetidine (H2) antagonist) causes a remarkable increase of the TCDD stimulating effect.

Adenylyl Cyclases↗
PubMed1978

Effects of bromocriptine on adenylate cyclase and phosphodiesterase activities of rat striatum.

The activity of 2-bromo-alpha-ergokryptine (bromocriptine) (5 mg kg-1, i.p.) on adenylate cyclase and on phosphodiesterase (PDE-PDE II) of rat striatum, has been examined both in vitro and in vivo. In vitro and in vivo bromocriptine stimulated adenylate cyclase activity, but reduced the stimulating effect of dopamine on adenylate cyclase activity. Bromocriptine showed a dose-dependent biphasic action on phosphodiesterases in vitro while in vivo it stimulated them. The results obtained proved bromocriptine to have an agonist-antagonist action at striatal dopamine receptor level, with a relevant effect on the cAMP system.

Adenylyl Cyclases↗