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G Romani

Publications and source records attributed to G Romani.

11 recordsLinked to original sources
PubMed2000

Morphology of somatosensory evoked fields: inter-hemispheric similarity as a parameter for physiological and pathological neural connectivity.

The morphology of somatosensory evoked fields (SEF) following electrical separate stimulation of left and right median nerve in 22 healthy volunteers was explored. The analysis of morphological properties of individual SEFs has been performed, in order to quantify an inter-hemispheric correlation coefficient. Despite a high inter-subject variability of the SEF morphologies, a high intra-subject inter-hemispheric shape correlation occurs in the post-stimulus epoch of 100 ms from the stimulus onset. Accordingly, a normative value for the parameter describing the SEF inter-hemispheric correlation coefficient has been calculated. The present work establishes quantitative and normative descriptions of the shape similarity of SEFs from the two hands in the left and right hemispheres. This provides a database for a new parameter, which might be useful in detecting alterations in the primary sensory cortical activation due to possible unilateral alterations of sensory inflow because of either peripheral or central deficits. The described procedure has been successfully applied to a small number of patients affected by unilateral cerebrovascular lesion.

Adult↗
PubMed1997

Effects of abscisic acid and cytoplasmic pH on potassium and chloride efflux in Arabidopsis thaliana seedlings.

The effects of ABA, isobutyric acid (IBA) and nicotine on K+ and Cl- efflux were studied in Arabidopsis thaliana seedlings, and the role of pHcyt and Em in the regulation of the efflux of these ions was discussed. The data show that treatments with IBA and nicotine influenced in opposite directions the efflux of either K+ or Cl-: K+ efflux was increased by nicotine and reduced in the presence of IBA, whereas Cl- efflux was stimulated by IBA and decreased by nicotine treatment. Under all the conditions tested ABA induced cytoplasmic acidification and inhibition of K+ and Cl- net efflux. Experiments aimed to estimate the individual contribution of pHcyt and Em in modulating K+ efflux indicated that, within the range of acidic pHcyt values, a regulation of K+ efflux was imposed by pHcyt on the control exerted by Em, the efflux being inhibited by lower pHcyt values. Conversely, in the alkaline side of pHcyt K+ efflux seemed linked only to the Em values. These results are consistent with the hypothesis that the decrease in K+ efflux observed in non-stomatal tissues in the presence of ABA may be mediated by the cytoplasmic acidification induced by the hormone.

Abscisic Acid↗
PubMed1986

Stimulation of Weak Acid Uptake and Increase in Cell Sap pH as Evidence for Fusicoccin- and K-Induced Cytosol Alkalinization.

In maize root segments fusicoccin induced a consistent increase in cell sap pH (taken as representative of vacuolar pH). This effect was markedly enhanced by the presence of K(+) in the medium, whereas in the absence of fusicoccin K(+) did not significantly influence cell sap pH. Treatment with a weak acid at 2 mm concentration inhibited the uptake of a different ((14)C-labeled) weak acid fed at a lower concentration, thus suggesting that acidification of the cytoplasm inhibits weak acid uptake. Fusicoccin and K(+) increased the rate of uptake of 5,5-dimethyloxazolidine-2,4-dione, butyric acid, or isobutyric acid slightly when fed separately, strongly when fed in combination. The synergism between fusicoccin and K(+) in stimulating weak acid uptake was parallel to that observed for the stimulation of H(+) extrusion. Application of the weak acid distribution method to a condition of ;quasi-equilibrium' indicated that fusicoccin induces a cytosolic pH increase of about 0.14 unit. These results are interpreted as providing circumstantial evidence that fusicoccin- and K(+)- induced stimulation of H(+) extrusion led to an alkalinization of the cytosol, and that other early metabolic responses, such as an increase in malate level, are a consequence of the increase in cytosolic pH.

Journal Article↗
PubMed1985

H extrusion and potassium uptake associated with potential hyperpolarization in maize and wheat root segments treated with permeant weak acids.

The rapid uptake of weak acids permeant in the uncharged form is accompanied in maize and wheat root segments by a hyperpolarization of the transmembrane electrical potential and an increase in K(+) uptake, suggesting a stimulation of the plasmalemma H(+) pump. The evaluation of weak acid-induced H(+) extrusion must take into account the alkalinization of the medium due to the rapid uptake of the uncharged form of the acid, partially masking the proton pump-mediated extrusion of H(+). The data corrected for this interference show that the lipophilic butyric acid and trimethyl acetic acid induce in maize and in wheat root segments a significant increase in ;real' H(+) extrusion, roughly matching the increase in net K(+) uptake. The presence of K(+) significantly increases the rate of uptake of the weak acid, possibly as a consequence of an alkalinization of the cytosol associated with K(+) absorption. In maize root segments, the effects of fusicoccin and those of butyric acid on both K(+) uptake and H(+) extrusion are clearly synergistic, thus suggesting distinct modes of action. These results support the view that the activity of the plasmalemma H(+) pump is regulated by the value of cytosolic pH.

Journal Article↗
PubMed1981

[2'Deoxyadenosine/adenosine deaminase ratio in pleural and peritoneal effusions. Diagnostic significance].

It has been observed that adenosine deaminase activity in human beings differ between serum and tissues reference to optimal pH, Km and relative substrate specificity. Based upon the ratio between the activity of deaminase on 2'deoxyadenosine and adenosine, we may distinguish between a "serum type" enzyme and a "tissue type" enzyme. In sample of pleural and peritoneal fluid extracted from 92 patients with variable pathology, we have found the existence of a "tissue type" enzyme in three patients having empyemic pleural effusions and ten with malignant systemic pathology.

Adenosine Deaminase↗
PubMed1981

[Serum 2'deoxyadenosine/adenosine deaminase ratio in clinical diagnosis].

In humans Adenosine Deaminase activity (ADA) differs in serum and tissues in pH optimum, Km, and relative substrate specificity. Thus, on the basis of a major or a minor activity on 2'Deoxyadenosine, a "serum type"enzyme can be distinguished from a "tissue type" enzyme. The examination of ADA or relative substrate specificity (ratio 2'Deoxyadenosine/adenosine deaminase) in the serum of 174 patients with variant pathology, revealed the occurrence of a "tissue type" enzyme in sera of acute Lymphoblastic Leukaemia patients.

Adenosine Deaminase↗
PubMedDate not supplied

Involvement of the plasma membrane Ca2+-ATPase in the short-term response of Arabidopsis thaliana cultured cells to oligogalacturonides.

Treatment of Arabidopsis thaliana cells with oligogalacturonides (OG) initiates a transient production of reactive oxygen species (ROS), the concentration of which in the medium peaks after about 20 min of treatment. The analysis of OG effects on Ca (2+) fluxes shows that OG influence both Ca (2+) influx and Ca (2+) efflux (measured as (45)Ca (2+) fluxes) in a complex way. During the first 10 - 15 min, OG stimulate Ca (2+) influx and decrease its efflux, while at successive times of treatment, OG cause an increase of Ca (2+) efflux and a slight decrease of its influx. Treatment with sub- micro M concentrations of eosin yellow (EY), which selectively inhibits the Ca (2+)-ATPase of plasma membrane (PM), completely prevents the OG-induced increase in Ca (2+) efflux. EY also suppresses the transient feature of OG-induced ROS accumulation, keeping the level of ROS in the medium high. The biochemical analysis of PM purified from OG-treated cells indicates that treatment with OG for 15 to 45 min induces a significant decrease in Ca (2+)-ATPase activation by exogenous calmodulin (CaM), and markedly increases the amount of CaM associated with the PM. During the same time span, OG do not influence the expression of At-ACA8, the main isoform of PM Ca (2+)-ATPase in suspension-cultured A. thaliana cells, and of CaM genes. Overall, the reported results demonstrate that the PM Ca (2+)-ATPase is involved in the response of plant cells to OG and is essential in regulation of the oxidative burst.

Arabidopsis↗
PubMedDate not supplied

[The endothelium].

It is well known that the endothelial cells represent one of the most active and versatile elements in the human organism. In fact apart from being the lining of the vessel wall they exert both antithrombotic and prothrombotic functions. Endothelial cells regulate the vasomotor tone and also have a part in the different immunological and inflammatory process. All these functions are possible because the endothelial cells produce many receptors on their surface. This paper is a review of the latest data on different roles played and substances produced by endothelial cells.

Animals↗