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Biomedical subjects

C Di Giulio

Publications and source records attributed to C Di Giulio.

49 records · Page 3Linked to original sources
PubMed1989

Stimulus interaction between CO2 and almitrine in the cat carotid chemoreceptors.

The hypothesis that augmentation of the carotid chemoreceptor response to hypoxia by almitrine is due in part to an increased response to CO2 was tested by using single or few fiber preparation of carotid body chemosensory fibers in 12 cats anesthetized with alpha-chloralose. To differentiate between the plausible mechanisms of effects, we also tested the responsiveness of the afferents to cyanide and nicotine before and after almitrine. After a saturation dose of almitrine (1 mg.kg-1 followed by 0.5 mg.kg-1.h-1) the chemosensory responses to CO2 strikingly increased even during hyperoxia: the afferents showing an increased transient peak activity at the onset of hypercapnia, an augmented steady-state response to CO2 stimulus, and a decreased arterial PCO2 stimulus threshold. Thus, the effect of almitrine on carotid chemoreceptor response to hypoxia could be explained, at least in part, by its multiplicative stimulus interaction with CO2. After almitrine, the chemoreceptor response to cyanide, which is dependent on arterial PO2, was not particularly augmented relative to those of nicotine. Accordingly, the O2-sensing mechanism does not appear to be the primary site of almitrine effect. The results also indicate that the site of CO2 chemoreception resides downstream from those of hypoxia.

Almitrine↗
PubMed1984

[Computerized system for the acquisition and analysis of bioelectric waves].

With collaboration of medicals, electronics and informatics; we have evaluated a method destined to be a potent instrument for the analysis and store of bioelectrical signal. The signal can be taken directly from the subjects or from a tape recorder; we can call again stored for evaluating the gradient grade, the integral and other mathematical evaluations of traits of a curves; in example EEG, EOG, PEV, etc.

Computers↗
PubMedDate not supplied

Correlations between protein kinase C zeta signaling and morphological modifications during rat heart development and aging.

From birth to aging the heart undergoes functional changes reflecting biochemical and ultrastructural modifications which imply apoptosis. This is a physiological process resulting from genetic programs closely associated with development and aging. During development apoptosis eliminates redundant cells leading to heart remodeling, while during aging it eliminates damaged or exhausted cells. In the present paper we analyze some molecular mechanisms involved with heart morphological modifications, especially in the neonatal heart which displays different features in the subendocardial and myocardial area. The high number of subendocardial apoptotic cells and the inverted ratio of Bcl-2/Bax molecule expression in the two heart compartments led us to hypothesize a different metabolism in the myocardium as compared with subendocardium. Moreover, we propose that PKC zeta may mediate this different response by activating Nf-kB pathway and by maintaining the balance between hypertrophic growth and apoptosis involved with remodeling of neonatal heart. Further, we underline that in the aged heart, where this pathway is not activated, such balance is not maintained.

Aging↗
PubMedDate not supplied

A scavenger role for nitric oxide in the aged rat kidney.

Progressive ageing is associated with an increment of biomolecules modified through oxidation as a result of the action of free radicals deriving from reactive oxygen species that attack biomolecules. During ageing many alterations of renal functions have been reported. Renal ageing is associated with a progressive decline of glomerular filtration, renal blood flow and augmented vascular resistance. The kidney is a very important source of inducible nitric oxide synthase (iNOS) in both epithelial and vascular structures. In this study we have investigated mRNA and protein iNOS expression and localization and nitric oxide (NO) production in young and aged rats. An increased expression of iNOS occurs in rat kidney during ageing. In the aged rat, an increase in the values of both iNOS-RNA and iNOS protein was observed through rtPCR and Western blot analysis. The activities of three isoforms of NOS were also seen. In the aged rat kidney the production of NO decreased, due to the reduction of the activities of the three NOS. This suggests that in the aged rat a progressive increase of superoxide anion does not imply an increase in the production of NO which functions as a scavenger molecule, causing oxidative stress with accumulation of reactive oxygen species (ROS).

Actins↗
PubMedDate not supplied

Protein kinase C zeta regulation of hypertrophic and apoptotic events occurring during rat neonatal heart development and growth.

The development and growth of the rat heart implies hyperplasia, which stops at birth, and hypertrophy, allowing cardiac mass to grow in response to programmed genetic events along with to haemodynamic overload. Moreover, hypertrophy is accomplished to apoptosis which controls the final number of myocardial cells, deletes vestigial structures, and takes part in remodelling the organ. Since at the basis of all these processes, which lead to the complete development of the heart, the activation of specific signalling pathways underlies, attention has been addressed to the role played in vivo by Protein Kinase C zeta (PKC zeta) in regulating NF-kB signalling system and intrinsic mitochondrial apoptotic route at days 1, 4, 10 and 22 of rat life. In fact, a role has been assigned to PKC zeta in indirectly phosphorylating IKBa, which peaks between 10 and 22 days, through a IKK determining, in turn, NF-kB activation, concomitantly to cytochrome c/Apaf 1 co-localization in the cytoplasm and caspase-9/caspase-3 activation, which leads to the occurrence of apoptosis. Thus a key role for PKC zeta in regulating the hypertrophic and apoptotic events leading to establishment of complete function in rat neonatal heart is here suggested.

Animals↗
PubMedDate not supplied

Effects of 50 Hz sinusoidal electromagnetic fields on MCP-1 and RANTES generated from activated human macrophages.

Extremely low frequency electromagnetic fields (ELF-EMF) induce cellular changes and modulate signal transduction pathways, and may be beneficial in the treatment of inflammatory diseases. In this paper we studied two inflammatory chemokines, MCP-1 and RANTES produced by human cultured isolated monocytes from peripheral blood, with or without PHA and in the absence or presence of 50 Hz magnetic field of 1.0 mT for 24 h. The production of MCP-1 and RANTES was determined by ELISA method. Here, we found that ELF-EMF strongly inhibited the production of these chemokines stimulated by PHA, while the control was not affected. Since MCP-1 and RANTES exert chemoattraction for several populations inflammatory leukocytes, the inhibitory effect of these chemokines could be one of the mechanisms by which ELF-EMF is therapeutic in inflammatory diseases.

Journal Article↗
PubMedDate not supplied

cAMP phosphodiesterase activity in diabetic rats eyes in normoxic, hypoxic and hyperoxic conditions.

Phosphodiesterase activity was tested on homogenized eyes of pre-diabetic rats kept in normoxic, hypoxic and hyperoxic conditions, with the aim of correlating any difference in PDE activity with variations in atmospheric oxygen contents. The activity of the cAMP phosphodiesterase (cAMP-PDE) was tested. Phosphodiesterases seem to be particularly susceptible to variations in oxygen tension, suggesting an important role of cyclic nucleotides in adaptive processes of the cell. cAMP-PDE activity increases slightly in normoxic, hypoxic and hyperoxic conditions in pre-diabetic rats. The second messenger, cAMP, plays important roles in mediating the biological effects of a wide variety of first messengers. The intracellular levels of cyclic nucleotides depend upon rates of synthesis and degradation, of cyclases and phosphodiesterase (PDEs), respectively. Therefore, PDEs seem to play an important role in a wide variety of physiological processes.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMedDate not supplied

cGMP phosphodiesterase activity in diabetic rats eyes in normoxic, hypoxic and hyperoxic conditions.

Phosphodiesterase activity was tested on homogenized eyes of pre-diabetic rats kept in normoxic, hypoxic and hyperoxic conditions, with the aim of correlating any difference in PDE activity with variations in atmospheric oxygen contents. The activity of the cGMP phosphodiesterase (cGMP-PDE) was tested. Phosphodiesterases seem to be particularly susceptible to variations in oxygen tension, suggesting an important role of cyclic nucleotides in cellular adaptive processes. cGMP-PDE activity increases lightly in normoxic, hypoxic and hyperoxic conditions in pre-diabetic rats. The second messenger, cGMP, plays important roles in mediating the biological effects of a wide variety of first messengers. In particular, cGMP in the eye is an important mediator for the mechanism of sight. The intracellular levels of cyclic nucleotides depend upon the rates of synthesis and degradation, actuated, respectively, by cyclases and phosphodiesterases (PDEs). Therefore, PDEs seem to play an important role in a wide variety of physiological processes.

3',5'-Cyclic-GMP Phosphodiesterases↗