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F Moroni

Publications and source records attributed to F Moroni.

At least 19 recordsLinked to original sources
PubMed1992

The response of human lymphocytes to phytohemagglutinin is impaired at different levels during aging.

Several parameters generally believed to be necessary for the activation and progression of proliferation of human lymphocytes have been investigated and compared with special reference to aging. The responding capacity of plasma membrane potential to depolarizing and also repolarizing conditions induced by exposure to mitogens like PHA was lower in lymphocytes from old donors as compared to those of young ones. This indicates a significant age-dependent difference in the readiness to respond to channel-activating perturbations. As an early signal of activation, after one hour PHA stimulation the merocyanine 540 uptake by the lipid regions was chosen, based on the property of this fluorescent probe to bind to loosely packed lipids of the plasma membrane. The proteins encoded by the c-myc and c-myb genes were chosen as markers of the G0/G1 and G1/S phased transition, respectively. The mean number of cells that increased the uptake of MC 540 following mitogenic stimulation did not differ in young vs. old individuals. However, 4 samples out of 10 from the old population showed lower MC 540 fluorescence than the lowest signal from the young population. The number of responding cells was decreased during aging when the presence of the c-myc protein was taken as its measure; and this decrease was further accentuated, determining the expression of the c-myb protein. This frequently encountered age-dependent pattern, however, was not followed by the lymphocytes of all old donors. One example is reported in which the MC 540 uptake, the c-myc and c-myb expression in the cells from one old subject fell in the range of the young subjects. However, even in this case, the response of the lymphocytes as measured by 3H-thymidine incorporation was only 64% of that of young subjects. For this sample, we found an impairment of the response at the mitochondrial level. In addition to these parameters, the amount of 3H-thymidine incorporated by the cells expressing the c-myb protein was calculated. The values in old individuals were lower than those in the young, suggesting that not all the cells expressing the c-myb protein were able to synthesize DNA in lymphocyte populations from the elderly. Our data support the view that the age-dependent decline of lymphocyte responsiveness to mitogens can be accounted for by impairments at different levels.(ABSTRACT TRUNCATED AT 400 WORDS)

Aging↗
PubMed1992

Bretylium-induced voltage-gated sodium current in human lymphocytes.

Using the whole-cell variation of the patch-clamp technique it has been determined that 0.25-3 mM bretylium tosylate (BT) exerts a repolarizing effect on partially depolarized human lymphocytes. The repolarizing effect was ouabain (40 microM)-sensitive, and was inhibited by the removal of external Na+ or by the Na(+)-channel-blocker amiloride (10-44 microM), but K(+)-channel-blockers 4-aminopyridine (0.1-5 mM) and quinine (100 microM) had no effect. The drug induced a sodium dependent, amiloride-sensitive transient inward current reaching its maximum value approx. 20-30 s after the administration of BT and lasting for 6-10 min. This current was activated by depolarization within 25 ms at around -42 mV, its inactivation took about 2 s and its reversal potential was +24 +/- 5 mV. An increase in the intracellular sodium concentration (1.8-3.2 mM) has been observed upon the addition of BT by monitoring the SBFI fluorescence of the dye-loaded cells. It has been shown that whole-cell K+ currents are significantly decreased by BT. The existence of voltage and ligand (BT)-gated sodium channels has been postulated in human lymphocytes. These channels are thought to participate in the initiation of membrane repolarization in human lymphocytes, and thereby influence mitogenic or antigen-induced cell-activation processes.

Bretylium Compounds↗
PubMed1992

General anaesthetics inhibit the responses induced by glutamate receptor agonists in the mouse cortex.

The effects of several general anaesthetics on the responses evoked by the excitatory amino acid agonists N-methyl-D-aspartate (NMDA) and alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionate (AMPA) were investigated in mouse cortical wedges placed in a two compartment bath and superfused with a nominally Mg(2+)-free Krebs solution. Chloroform (3-6 mM) and halothane (1-3 mM) preferentially antagonized AMPA responses; thiopental (0.1-0.4 mM), diethyl ether (10-30 mM) and isoflurane (1-3 mM) antagonized both AMPA or NMDA responses while ketamine antagonized NMDA responses in a highly selective way. The antagonism of the excitatory amino acid responses exerted by the anaesthetics was non competitive in nature. The inhibition of excitatory amino acid receptor function may be one of the mechanisms whereby general anaesthesia is produced.

Anesthetics↗
PubMed1992

Thiokynurenates prevent excitotoxic neuronal death in vitro and in vivo by acting as glycine antagonists and as inhibitors of lipid peroxidation.

Several derivatives of kynurenic and thiokynurenic acids were synthesized and tested for their ability to protect primary cultures of cerebellar granule cells against excitotoxic damage, and to affect the binding of [3H]glycine ([3H]Gly), [3H]alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid ([3H]AMPA), [3H]3-(2-carboxypiperazine-4-yl-)propyl-1-phosphonic acid ([3H]CPP), [3H]kainic acid and [3H]N-[1-(2-thienyl)cyclohexyl]-3,4-piperidine ([3H]TCP) to rat cortical membranes. Kynurenic and thiokynurenic acid derivatives with one or two halogens in position 5 or 7 were selective glycine antagonists, failing to affect N-methyl-D-aspartate (NMDA), kainate or AMPA sites at micromolar concentrations. 7-Cl-kynurenic, 7-Cl-thiokynurenic, 5,7-diCl-kynurenic and 5,7-diCl-thiokynurenic acids had similar IC50s for displacing [3H]Gly from its strychnine-insensitive site and for reducing the stimulated (0.5 microM NMDA and 1 microM glycine) [3H]TCP binding to cortical membranes. However, 7-Cl-thiokynurenic acid was particularly potent to prevent excitotoxic neuronal death in cultured cerebellar granule cells. This action may be ascribed to inhibition of lipid peroxidation, a property which was demonstrated for the 5- or 7-Cl derivatives of thiokynurenic acid. Furthermore, 7-Cl-thiokynurenic acid reduced excitotoxic damage caused by the injection of quinolinic acid in the rat striatum. Thus, 7-Cl-thiokynurenic acid appears to be a new compound with interesting antiexcitotoxic properties both in vitro and in vivo.

Animals↗
PubMed1992

Cholesterol-rich rabbit serum modulates beta-adrenergic receptor density of human lymphocytes. A possible role of LDL-cholesterol.

The effect of in vitro treatment of human lymphocytes with rabbit cholesterol-rich serum (RCS) on the membrane microviscosity as well as on the beta-adrenergic receptor density has been investigated. RCS treatment of cells resulted in a 30% decrease of receptor density without any effect on membrane microviscosity. A complete recovery was observed incubating the RCS cells either with the "Active Lipids" (AL) or with heparin. The AL are a mixture of neutral lipids, phosphatidylcholine and phosphatidylethanolamine from hen egg yolk known to fluidify the cell membrane. The AL modified membrane microviscosity of control lymphocytes without altering their beta-receptor number. These observations support the proposition that beta-receptor density of human lymphocytes is not regulated by membrane microviscosity and suggest that probably low density lipoprotein-cholesterol complex is involved in such a regulation.

Animals↗
PubMed1992

GM1 ganglioside reduces ischemia-induced excitatory amino acid output: a microdialysis study in the gerbil hippocampus.

The effects of transient forebrain ischemia on the extracellular concentration of the excitatory amino acids glutamate and aspartate were studied in the gerbil hippocampus using microdialysis. Bilateral carotid occlusion (8 min) increased glutamate and aspartate concentration in the dialysate by 3- to 8-fold. This increase lasted 20-30 min. When the animals were pretreated with GM1 ganglioside (30 mg/kg/day, i.p., for 3 days), the ischemia induced increase of excitatory amino acids in the dialysate was significantly reduced. The results are in line with the hypothesis that systemic GM1 ganglioside administration may reduce ischemia-induced brain damage.

Animals↗
PubMed1992

Glutathione influences the proliferation as well as the extent of mitochondrial activation in rat splenocytes.

The time-dependent changes of mitochondrial membrane potential and mass have been investigated on rat splenic lymphocytes stimulated with Con A in the presence and absence of reduced glutathione (GSH). Rhodamine-123 (Rh-123) and nonyl acridine orange (NAO) were used as specific dyes to monitor the membrane potential and mass of mitochondria, respectively. The percentage of cells showing blast transformation and the level of Rh-123 or NAO uptake were analyzed by flow cytometry. Present results demonstrate that a large number of cells showed activated mitochondria already at 24 hr after Con A stimulation and the activation of these organelles was not related to blast transformation. The addition of GSH into the culture medium increased the number of cells responding to mitogenic stimulation. In parallel it augmented the percentage of lymphocytes with activated mitochondria and also prevented their depolarization.

Animals↗
PubMed1992

Phytohemagglutinin induced changes of membrane lipid packing, c-myc and c-myb encoded protein expression in human lymphocytes during aging.

Three parameters which signal different stages of cell activation were analyzed in lymphocytes from young and old subjects. Merocyanine 540 (MC-540) incorporation into the membrane lipid phase was used as a very early marker of activation and was measured after 1 h of phytohemagglutinin (PHA) stimulation. The proteins coded by c-myc and c-myb protooncogenes were determined by appropriate antibodies and were taken as markers of the G0/G1 and G1/S phase transition, respectively. The number of cells which increased the uptake of MC-540 following PHA stimulation did not differ when comparing young and old individuals. Both the number of the responding cells and the size of the response were decreased during aging when the presence of the c-myc protein was taken into account. A consistent decrease of the percentage of lymphocytes able to express the c-myb protein was observed in the cells from old donors as compared to those from the young ones, but the amount of detectable protein per cell remained unchanged. Our data suggest that the deficiency of responsiveness which accompanies aging is due to impairments at different points of the cell cycle. The very low number of cells expressing the c-myb protein is likely the result of step by step elimination of those cells not able to fulfill the requirements to progress along the cell cycle.

Adult↗
PubMed1992

A sodium channel opener inhibits stimulation of human peripheral blood mononuclear cells.

The role of membrane potential changes in T cell activation was studied on human peripheral blood lymphocytes stimulated with phytohemagglutinin. Addition of bretylium tosylate, a sodium channels opener, to PHA treated lymphocytes modified the membrane potential and consequently blocked cell activation in a dose-dependent fashion. BT was non-toxic even in long-term (72 hr) incubations. It was reversibly removable, and the removal restored the stimulatory effect of PHA. 3H-thymidine incorporation was blocked if BT was present during the first 20-24 hr of the mitogenic activation. The later BT was added after PHA, the less inhibition of proliferation was observed. BT hyperpolarized the lymphocytes also in the presence of PHA. BT hindered the depolarizing effect of high extracellular potassium concns. The sustained polarized state of the lymphocytes did not influence the intracellular calcium increase upon PHA treatment. IL-2 and transferrin receptor expression was not hindered by BT during PHA stimulation of lymphocytes. Addition of rIL-2 did not abolish the inhibitory effect of BT. According to cell-cycle analysis BT arrested the majority of the cells in G1 phase. It is suggested that cell activation demands the flexible maintenance of a relatively narrow membrane potential "window". Any sustained and significant hyper-, or depolarization, may dramatically decrease the effectivity of transmembrane signalling.

Bretylium Tosylate↗
PubMed1992

Nicotinylalanine increases the formation of kynurenic acid in the brain and antagonizes convulsions.

Kynurenic acid (KYNA) was quantified in the extracellular spaces of the rat hippocampus using microdialysis and HPLC (fluorimetric detection) to study the possible role of this tryptophan metabolite in the modulation of the function of the N-methyl-D-aspartate (NMDA) receptor. Addition of probenecid (1 mM), which is an inhibitor of the organic acid transport system, to the Ringer's solution perfusing the dialysis probe increased the KYNA concentration in the dialysate from 10.4 +/- 0.9 to 48 +/- 6 nM. Addition of 2 mM aminooxyacetic acid, a nonspecific inhibitor of KYNA synthesis, reduced this concentration by 50%. These data suggest that KYNA is continuously synthesized in the rat hippocampus. Nicotinylalanine (NAL), 200-400 mg/kg i.p., an analogue of kynurenine that is able to direct the flow of tryptophan metabolites toward the synthesis of KYNA, significantly increased the KYNA concentration in the hippocampal dialysate and significantly potentiated the effect of tryptophan on the accumulation of KYNA in the brain and other organs. This increase resulted in pharmacological actions compatible with an antagonism of the NMDA receptors. In fact, NAL antagonized sound-induced seizures and prevented death in DBA/2 mice. Pretreatment of the mice with D-serine (100 micrograms intracerebroventricularly), a glycine agonist and a competitive antagonist of KYNA, completely prevented the anticonvulsive action of NAL. These data suggest that changes in the extracellular concentration of KYNA in the brain are associated with a modulation of NMDA receptor function.

Alanine↗
PubMed1992

Ureterocalicostomy in the treatment of pyeloplasty failures.

Ureterocalicostomy was performed in 8 patients following failed pyeloplasty: 2 had undergone two previous pyeloplasties, while endourological management had been attempted in 3. With a mean follow-up of 58.7 months, radiographic studies demonstrated resolution of the obstruction in 6 cases (75%), while two kidneys lost their function. The definitive role of endourological techniques after pyeloplasty failure still waits the test of time although they deserve to be applied first, and ureterocalicostomy remains a reliable procedure in this particular setting.

Adult↗
PubMed1992

Characterization of 2,4,5-trihydroxyphenylalanine neurotoxicity in vitro and protective effects of ganglioside GM1: implications for Parkinson's disease.

The neurotoxic properties of 2,4,5-trihydroxyphenylalanine (TOPA; the 6-hydroxylated derivative of dopa) was investigated in cultures of central neurons. Application of solutions of TOPA to cerebellar granule cells resulted in a concentration- and time-dependent neuronal death, with prolonged (24 hr) exposure producing a clear left-handed shift in the dose-response relationship from the one observed with a 60-min exposure (LD50: 4 and 29 microM, respectively). This toxicity was largely blocked by the non-N-methyl-D-aspartate antagonist 6-cyano-7-nitroquinoxaline-2,3-dione. Solutions of TOPA were also toxic to mesencephalic neurons after acute or chronic exposure, displaying the same leftward shift in LD50. This latter preparation contained a minor population of dopaminergic, tyrosine hydroxylase immunopositive cells which were likewise sensitive to the excitotoxic effects of TOPA. Neurotoxic activity of TOPA appeared to depend upon its oxidation in solution, as judged using chemical analysis and reducing agents. The monosialoganglioside GM1 was effective in protecting against neurodegeneration induced by brief or prolonged exposure to solutions of TOPA. These results suggest that an abnormal production or accumulation of TOPA or its oxidation product(s) might be involved in excitotoxicity directed to areas of the brain with dopaminergic innervation, and in other brain areas in Parkinson's disease patients on long-term dopa therapy. The selective action of gangliosides in disrupting the pathological consequences of glutamate receptor activation proposes their use as chemoprophylactic agents for preventing or arresting the neuronal losses accompanying such situations.

6-Cyano-7-nitroquinoxaline-2,3-dione↗
PubMed1992

Lipid peroxidation causes an increase of lipid order and a decrease of 5'-nucleotidase activity in the liver plasma membrane.

The effect of peroxidation on 5'-nucleotidase activity as well as on membrane microviscosity has been investigated in liver plasma membranes from Wistar rats. The peroxidation was performed with 100 microM H2O2 and 200 microM FeSO4 and/or with 5 mM t-butylhydroperoxide. Treatment of the membranes with these oxidizing agents resulted in an elevation of the transition temperatures of the polarization of the lipid fluorescent probes 1,6 diphenyl-1,3,5 hexatriene (DPH), 3-p-(6-phenyl) 1,3,5 hexatriene phenylpropionic acid (PA-DPH) as well as of the fluorescent thiol reagent N-(1-pyrene) maleimide (1-PM). The peroxidation resulted in a decrease of the activity of 5'nucleotidase. Our data support that the increase of membrane microviscosity of the lipid domain regulates the activity of 5'-nucleotidase.

5'-Nucleotidase↗
PubMed1992

[The "in situ" treatment of ureteral calculi with extracorporeal lithotripsy].

The authors report on 80 cases of ureteral calculi treated with in situ extracorporeal shock wave (ESWL), with no retrograde or antegrade maneuvers. Success rate was high (97.5%). Forty-two calculi were located in the proximal ureter above the sacroiliac joint; 10 were in the pre-sacral ureter, and 28 in the pelvic ureter, below the inferior border of the sacroiliac joint. After ESWL, double-J stents were positioned in 5 patients and nephrostomy was performed in 4 cases with positioning of 7-F pig-tail catheters; 8 patients (10%) underwent additional post-lithotripsy urologic and radiologic examinations. Lithotripsy having failed in 2 patients (2.5%), surgery with ureterolithotomy was performed. In situ ESWL of ureteral calculi emerges from this trial as the treatment of choice and not as an alternative to urologic maneuvers or open surgery with ureterolithotomy: the latter methods are necessary only after ESWL failure.

Adult↗
PubMed1991

Thiokynurenates: a new group of antagonists of the glycine modulatory site of the NMDA receptor.

Several substituted derivatives of kynurenic acid were tested on the N-methyl-D-aspartate (NMDA) receptor/ion channel complex present in the guinea pig myenteric plexus, on the binding of [3H]glycine and of [3H]N-[1-(2-thienyl)cyclohexyl]piperidine [( 3H]TCP) to rat cortical membranes and on the depolarization of mice cortical wedges induced by NMDA or quisqualic acid (QA). Kynurenic acid derivatives, having a chlorine (CI) or a fluorine atom in position 5 or 7 but not in position 6 or 8 had significantly lower IC50s than the parent compound when tested on the antagonism of glutamate-induced ileal contraction and in the glycine binding assay. A further significant increase in potency was obtained by substituting a thio group for the hydroxy group in position 4 of kynurenic acid: the IC50 was 160 +/- 20 microM of kynurenic acid and 70 +/- 15 microM of thiokynurenic acid in the myenteric plexus whereas these IC50s for glycine binding were 25 +/- 3 and 9 +/- 2 microM respectively. Several thiokynurenic acid derivatives were synthetized and showed an increased affinity for the glycine recognition site over the corresponding kynurenic acid derivatives. Glycine competitively antagonized the actions of the thiokynurenates in the ileum, in cortical wedges and on [3H]TCP binding. In this preparation, 7-Cl-thiokynurenic acid had an IC50 of 8 microM for antagonizing 10 microM NMDA-induced depolarization while 50% of the 10 microM QA depolarization was antagonized at 300 microM. Thus thiokynurenic acid derivatives seem to be a new group of potent and selective antagonists of strychnine-insensitive glycine receptors.

Animals↗
PubMed1991

Ischemia does not induce the release of excitotoxic amino acids from the hippocampus of newborn rats.

Simulated ischemic conditions or a source of oxygen-derived free radicals, such as xanthine plus xanthine oxidase, released a significant amount of the excitotoxic amino acids Asp and Glu from adult rat hippocampal slices incubated in vitro. The concentrations of Asp and Glu in the incubation medium increased by 20 and 30 times respectively when such slices were exposed to simulated ischemia for a 10-min period. However, preparations obtained from 4- to 9-day-old rats did not release Asp or Glu either when exposed to ischemia or after K+ depolarization. This release appeared 10-15 days after birth and progressively increased up to 13 months of age. No further increase was observed in 25-month-old animals. The exposure of the slices to a source of oxygen-derived free radicals induced a release of excitotoxic amino acids independently from the age of the rats. The massive excitotoxic amino acid release from adult hippocampal slices and the formation of free radicals induced by ischemic insults has been previously associated with degeneration of hippocampal neurons. The lack of ischemia-induced excitotoxic amino acid release from the newborn hippocampus may help to explain why the newborn hippocampus is more resistant than the adult to hypoxic/ischemic insults.

Aging↗