PubMed Health⌕ Search

Biomedical subjects

F Nicoletti

Publications and source records attributed to F Nicoletti.

At least 199 records · Page 11Linked to original sources
PubMed1993

The effect of cefepime on some immune parameters in vitro: lack of interference with mitogen-induced lymphoproliferation, immunoglobulin synthesis, IFN-gamma and IL-2 secretion and IL-2 receptor expression.

The possible interference of the novel antibiotic cefepime (CPE) with some functions of the immune system was investigated in vitro. Peripheral blood mononuclear cells (PBMC) cultured in the presence of drug concentrations ranging from 25 to 100 micrograms/ml normally maintained their responsiveness to polyclonal (PHA, Con A, PWM) mitogenic stimulation in regard to proliferative response, IgM and IgG synthesis and IFN-gamma and IL-2 secretory capacity. Moreover, PHA-induced expression of IL-2 receptors was comparable in PBMCs cultured in the presence or absence of CPE. Taken together, these data suggest that CPE does not interfere, at this specific level, with T- and B-cell mediated functions in vitro.

Adult↗
PubMed1993

Prevention of cyclophosphamide-induced diabetes in the NOD/WEHI mouse with deoxyspergualin.

Ten out of 20 (50%) 17-week-old female NOD/WEHI mice developed an acute form of autoimmune diabetes when injected with two large doses of cyclophosphamide (CY), given at 14-day intervals. If these mice were treated under a prophylactic regimen with 2.5 mg/kg body weight per day of the novel immunosuppressant deoxyspergualin (DSP) the onset of diabetes was completely prevented. Moreover, DSP-treated animals showed reduced signs of pancreatic insulitis, had lower percentages of splenic lymphoid cells (SLC) expressing IL-2 receptors and Ly-6C antigens on their surfaces, and these cells released lower amounts of interferon-gamma (IFN) when stimulated in vitro. These data, providing evidence for the capacity of DSP to protect NOD/WEHI mice from experimental autoimmune diabetes and to modulate histo-immunological pathogenic pathways, indicate DSP as a drug of potential interest in the treatment of human insulin-dependent diabetes mellitus.

Animals↗
PubMed1993

Metabotropic glutamate receptors in cultured cerebellar granule cells: developmental profile.

Excitatory amino acid (EAA)-induced polyphosphoinositide (PPI) hydrolysis was studied during the development in culture of cerebellar granule cells. The developmental pattern was similar using metabotropic glutamate (Glu) receptor (mGluR) agonists, including L-Glu, quisqualate, and trans-(+/-)-1-amino-1,3-cyclopentanedicarboxylic acid: The stimulation of [3H]inositol monophosphate ([3H]-InsP) formation was low at 2 days in vitro (DIV), but the response increased steeply, reaching a peak at 4 DIV, followed by a progressive decline. In contrast, carbamylcholine-induced PPI hydrolysis exhibited a plateau after a pronounced increase during the first week in vitro. At 6 DIV, but not at 4 DIV, when the activity peaked, PPI hydrolysis elicited by Glu was reduced by the N-methyl-D-aspartate (NMDA) receptor antagonist MK-801, indicating that in cultured granule cells, NMDA receptors contribute to [3H]-InsP formation and that this component of the response develops relatively late. Accordingly, NMDA-induced [3H]-InsP formation, estimated under Mg(2+)-free conditions, increased markedly from very low values at 2 DIV to a plateau at 8-10 DIV. The developmental pattern of EAA-induced PPI hydrolysis was paralleled by changes in the level of an mRNA for a specific mGluR subtype (mGluR1 mRNA). RNA blot analysis performed with the pmGR1 cDNA probe revealed that the hybridization signal in RNA extracts from cultures at 1 DIV was very weak, but mGluR mRNA levels increased dramatically between 1 and 3 DIV, followed by a progressive decrease, so that by 15 DIV the mRNA levels were only approximately 10% of the values at 3 DIV.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗
PubMed1993

Induction of primary response genes by excitatory amino acid receptor agonists in primary astroglial cultures.

We have characterized the genomic response of astroglial cells to excitatory amino acids by using selective agonists and antagonists for the various receptor subtypes and by analyzing different primary response genes, such as members of the Fos (c-fos and fosB) and Jun (c-jun, junB, and junD) families, zif/268, and c-myc. A rapid and transient elevation of mRNA levels for c-fos, fosB, c-jun, junB, and zif/268 was observed after addition of glutamate to cultured astrocytes, whereas junD and c-myc expression was not affected. The level of AP-1 DNA binding activity, as measured by the electrophoretic mobility shift assay, also increased after addition of glutamate to cultured astrocytes. Glutamate-induced c-fos expression was not affected by the N-methyl-D-aspartate receptor antagonists MK-801 and D-2-amino-5-phosphonopentanoate, by the kainate/alpha-amino-3-hydroxy-5- methylisoxazole-4-propionate (AMPA) receptor antagonist 6,7-dinitroquinoxaline-2,3-dione (DNQX), or by the broad-spectrum antagonist kynurenate. Kainate and AMPA were also effective in inducing primary response gene expression, and their actions were antagonized by kynurenate and DNQX but not by MK-801. 1S,3R-1-Aminocyclopentane-1,3-dicarboxylic acid, a selective agonist for the metabotropic glutamate receptor, induced primary response gene expression, but its action was not antagonized by different glutamate antagonists, including L-2-amino-3-phosphonopropionate. In conclusion, our data suggest that cultured astrocytes express both kainate/AMPA ionotropic receptors and metabotropic receptors coupled to the rapid and coordinated activation of different classes of transcriptional factor genes.

Animals↗
PubMed1993

Growth conditions differentially regulate the expression of alpha-amino-3-hydroxy-5-methylisoxazole-4-propionate (AMPA) receptor subunits in cultured neurons.

We have studied the expression of alpha-amino-3-hydroxy-5-methylisoxazole-4-propionate (AMPA) receptor subunits in cultured cerebellar granule cells [7 days in vitro (DIV)] grown in medium containing different concentrations of K+ (10, 25, or 40 mM) with or without 100 microM N-methyl-D-aspartate (NMDA; added once after 2 DIV). All these conditions are known to influence maturation and survival of granule cells, as well as the functional expression of NMDA receptors during development in culture. The expression of both glutamate receptor (GluR) subunit 1 mRNA and receptor protein was low in cultures grown in 10 mM K+ (K10) and increased dramatically in cultures grown in 25 mM K+ (K25), with intermediate levels found in cultures grown in K10 and chronically exposed to NMDA (K10 + NMDA). In cultures grown in 40 mM K+ (K40), the expression of GluR1 mRNA and receptor protein was lower than in K25 but still higher than in K10. GluR2 and -3 subunits were differently regulated by growth conditions, with their expression being higher in K10 and progressively reduced to the lowest levels in K40 (both mRNA and receptor proteins). GluR4 mRNA levels did not differ between K10 and K25, although they were reduced by chronic exposure to NMDA. To test how the differential expression of the various subunits affects the functional activity of AMPA receptors, we have measured AMPA-stimulated 45Ca2+ influx and 4 beta-[3H]phorbol 12,13-dibutyrate binding in intact cells. Both functional parameters increased along with the K+ concentration and were maximal in K40, in coincidence with the lowest expression of the GluR2 subunits.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Mechanisms underlying developmental changes in the expression of metabotropic glutamate receptors in cultured cerebellar granule cells: homologous desensitization and interactive effects involving N-methyl-D-aspartate receptors.

Glutamate receptors coupled to polyphosphoinositide (PPI) hydrolysis (metabotropic glutamate receptors, mGluR), are highly efficient during the early stages of postnatal life and are thought to be involved in developmental plasticity. The dramatic decrease with age in mGluR activity suggests the existence of mechanisms that down-regulate this receptor after a certain stage of neuronal maturation. In cultured cerebellar granule neurons grown under conditions that promote the survival and maturation of cells (serum-containing medium with 25 mM K+), enzymatic depletion of extracellular glutamate prevented the age-dependent decrease in mGluR agonist-stimulated PPI hydrolysis that normally occurs after 4 days of maturation in vitro, suggesting that mGluR activity declines as a result of developmental changes affecting homologous desensitization. This was borne out by the observation that glutamate at low concentrations (1-10 microM) readily desensitized mGluR at 7 days but not at 4 days in culture. Furthermore, the critical period during which the high sensitivity to agonist-induced desensitization of mGluR developed coincided with the period when phorbol ester-activated protein kinase C acquired the ability to suppress mGluR activity. The developmental pattern of mGluR agonist-induced PPI hydrolysis was similar in granule cells grown under "trophic" and "nontrophic" conditions (in cultures in 25 mM K+ and in a medium containing "low" K+, in this study, 10 mM, respectively). However, the developmental decline in the response to mGluR stimulation after 4 days in vitro was not prevented in cells grown in 10 mM K+ by the removal of extracellular glutamate; rather, it could be counteracted by treatment with N-methyl-D-aspartate (NMDA) (EC50, approximately 4 microM), which blocked the development of mGluR desensitization. The effect was NMDA receptor mediated and required DNA transcription and protein synthesis. However, NMDA exerted a different effect in cells grown in 25 mM K+, inducing a substantial decrease rather than an increase in mGluR activity. The effect of growth conditions was also examined on mGluR mRNA levels, which were not always correlated with mGluR activity. In general, either increases in the medium K+ concentrations or NMDA supplementation of the cultures resulted in a decrease in mGluR mRNA levels. It is noteworthy that NMDA could also restore mGluR activity after the metabotropic response had reached its peak. This implies that NMDA receptor activation may be involved in the increase in mGluR activity in adult life under conditions that elicit plastic changes in the nervous system.

Aging↗
PubMed1992

Thyrotropin releasing hormone (TRH) and its analog, RGH-2202, accelerate maturation of cerebellar neurons in vitro.

We have studied the "trophic" action of thyrotropin releasing hormone (TRH) in cultured cerebellar granule cells, a pure and homogeneous population of glutamatergic neurons. As an index of neuronal maturation, we have measured the uptake of D-[3H]aspartate (a non-metabolizable analog of glutamate) at different days of maturation in vitro (DIV). In control cultures, D-[3H]Aspartate increased linearly during maturation reaching plateau values between 7 and 9 DIV; daily addition of TRH tartrate (TRH-t) or RGH-2202 (a TRH analog) accelerated in a concentration-dependent manner the maturation profile of D-[3H]aspartate uptake. This effect was more pronounced for RGH-2202: in cultures treated daily with RGH-2202, D-[3H]aspartate uptake was fully expressed after 3 DIV. Neither TRH-t nor RGH-2202 significantly increased D-[3H]aspartate uptake in mature cells, excluding a direct action on the glutamate transport system. Both compounds specifically potentiated the increase in [3H]inositol monophosphate formation (but not the stimulation of 45Ca2+ influx) induced by N-methyl-D-aspartate (NMDA) receptor agonists, without affecting the stimulation of inositol phospholipid hydrolysis by quisqualate or carbamylcholine. We suggest that, in cultured cerebellar granule cells, TRH and RGH-2202 enhance the trophic action of endogenous glutamate by amplifying some of the intracellular events that follow the influx of extracellular Ca2+ through NMDA-gated ion channels.

Analysis of Variance↗
PubMed1992

Melittin enhances excitatory amino acid release and AMPA-stimulated 45Ca2+ influx in cultured neurons.

Melittin, a potent activator of phospholipase A2, enhanced both spontaneous and depolarization-induced release of D-[3H]aspartate in primary cultures of cerebellar granule cells. The action of melittin was concentration-dependent (EC50 value = 300 ng/ml) and did not require the presence of extracellular Ca2+. Melittin also stimulated the release of glutamate and aspartate, in addition to other endogenous amino acids (taurine, alanine and gamma-aminobutyric acid). These effects were accompanied by an enhanced influx of 45Ca2+, which was in part mediated by the activation of excitatory amino acid receptors by endogenous agonists. Low concentrations of melittin (50 ng/ml) potentiated the efficacy of AMPA in stimulating 45Ca2+ influx without affecting stimulation by kainate or by glutamate added in the absence of extracellular Mg2+ (a condition that favors the activation of NMDA receptors). These results indicate that activation of phospholipase A2 evokes both an enhanced glutamate release and an increased sensitivity of AMPA receptors, two events that may support synaptic facilitation and LTP formation.

Amino Acids↗
PubMed1992

Epidemiological survey of multiple sclerosis in Catania city.

The findings of an epidemiological survey of multiple sclerosis (MS) in the urban area of Catania reveal a new and in some respects original pattern of MS cases recorded on 31 December 1989 (prevalence day). They explain why special attention should be paid to patients residing in that area, which shows a remarkable upward trend of the MS prevalence rates calling for further study and for more targeted intervention in the fields of prevention, treatment and rehabilitation.

Adolescent↗
PubMed1992

Antibodies to endothelial cells in primary vasculitides mediate in vitro endothelial cytotoxicity in the presence of normal peripheral blood mononuclear cells.

Twenty-eight out of 62 patients with Wegener's granulomatosis and micropolyarteritis display circulating antiendothelial cell antibodies (AECA) detectable by a cell surface radioimmunoassay. These antibodies do not induce an in vitro endothelial damage either alone or in the presence of fresh complement; however, 50% of IgG-AECA positive sera can be cytotoxic in the presence of human normal peripheral blood mononuclear cells (PBM) at high effector/target ratios. The specificity of the PBM-mediated cytotoxicity is supported by the absence of the phenomenon in AECA negative sera, by the disappearance of the lytic effect after absorption of AECA, and by the finding that cellular-mediated cytotoxicity can be reproduced by purified IgG-AECA positive fractions. On the contrary, polymorphonuclear leukocytes or adherent mononuclear cells are not involved in such a cytotoxic activity. AECA seem to be directed against determinants consitutively expressed on the endothelial surface since the activation of endothelial cells by interleukin-1 beta or interferon-gamma affects neither the antibody binding nor their ability to mediate 51Cr release in the presence of PBM. These findings favor the hypothesis for a possible direct pathogenetic role of circulating AECA in the in vivo vascular damage.

Adult↗
PubMed1992

Enrichment of IgG anti-DNA-producing lymphoblastoid cell lines by antigen-coated immunomagnetic beads.

In this paper we describe the establishment of four anti-DNA-producing lymphoblastoid cell lines (LCL) by Epstein-Barr virus (EBV) infection of peripheral blood B-cells from a patient with systemic lupus erythematosus. The LCL showed a heterogeneous cell composition: the frequencies of cells in active proliferation, cells secreting IgG or IgM, and cells effectively producing IgG or IgM anti-DNA were estimated by limiting dilution analysis. The cells producing anti-DNA antibodies were a small fraction of the whole cell population constituting the LCL. In order to enrich the fraction of cells producing the desired antibody we performed a positive selection by DNA-coated immunomagnetic beads. Results show that in two out of three IgG anti-DNA-secreting LCL the frequency of DNA-producing cells increased after incubation with DNA-coated beads. At variance, IgM anti-DNA-secreting cells were completely lost after immunomagnetic separation. This approach could represent a further tool to obtain better fusion partners to construct stable hybrids secreting human monoclonal antibodies. The advantages of the presented technique would be: (a) removing of the fraction of low-affinity IgM-producing cells, which is often prevalent in EBV-induced LCL; and (b) the enrichment of IgG anti-DNA producing cells, which better represent the antibodies involved in the pathogenesis of the disease.

Adult↗
PubMed1992

Ubiquinone protects cultured neurons against spontaneous and excitotoxin-induced degeneration.

Ubiquinone is an endogenous quinone with pharmacological actions mainly related to its antioxidant properties. Here we report that ubiquinone protects cultured cerebellar granule cells against glutamate-induced neurotoxicity. In control cultures at 9 days of maturation in vitro (DIV), a 30-min exposure to 100 microM glutamate induced neuronal degeneration, as reflected by the great percentage (greater than 90%) of cells labeled with propidium iodide 24 h after the exposure. Glutamate-induced neuronal death was dramatically reduced in cultures treated daily with ubiquinone since the second DIV. In these cultures, glutamate failed to induce a "delayed" increase in the influx of 45Ca2+, an established parameter of excitotoxicity. Similarly, repeated addition of ubiquinone attenuated in a concentration-dependent manner the age-dependent degeneration of granule cells that is due to the toxic action of the endogenous glutamate progressively released into the medium. These results suggest that ubiquinone may be a useful drug in the therapy of acute and chronic neurodegenerative diseases related to hyperactivity of excitatory amino acid neurotransmission.

Animals↗
PubMed1992

The effects of deoxyspergualin on the development of diabetes in diabetes-prone BB rats.

The effects of the administration of the recently discovered immunosuppressant 15-Deoxyspergualin (DSP) on the development of insulin-dependent diabetes mellitus (IDDM) in diabetes-prone BB rats were studied. The data show that 2 mg/kg body weight DSP, administered six times a week from the 30th day up to the 105th day of age, significantly reduced the incidence of diabetes in diabetes-prone BB rats as compared with the PBS-injected controls. The drug was also able to reduce the signs of pancreatic insulitis and the percentages of W3/25+ and OX6+ splenocytes. Interruption of the treatment resulted in a later onset of diabetes in a high percentage of animals within 41 days. These findings suggest that 15-DSP may temporarily reverse the pathogenic mechanisms leading to beta cell destruction and autoimmune diabetes in a well-known experimental model of human insulin-dependent diabetes mellitus.

Animals↗
PubMed1992

Developmental changes in the modulation of cyclic AMP formation by the metabotropic glutamate receptor agonist 1S,3R-aminocyclopentane-1,3-dicarboxylic acid in brain slices.

Metabotropic glutamate receptors (mGluRs) have been recently described as a family of guanine nucleotide-binding regulatory protein-coupled receptors with multiple signal transduction pathways. At least one of these receptors appears to be negatively coupled to adenylyl cyclase when stably expressed in transfected cells. We have studied how activation of native mGluRs modulates cyclic AMP (cAMP) formation in brain slices prepared from rats at different ages. 1S,3R-1-Aminocyclopentane-1,3-dicarboxylic acid (1S,1R-ACPD), a selective agonist of mGluRs, slightly increased basal cAMP formation but reduced forskolin-stimulated cAMP formation in adult hippocampal slices, in agreement with previous results. The action of 1S,3R-ACPD on basal cAMP formation was not reproduced by the ionotropic receptor agonists N-methyl-D-aspartate, kainate, and alpha-amino-3-hydroxy-5-methylisoxazole-4-propionate and was antagonised by L-2-amino-3-phosphonopropionate (L-AP-3). L-AP-3, however, did not prevent but rather mimicked the inhibitory action of 1S,3R-ACPD on forskolin-stimulated cAMP formation. In hippocampal slices from 1-, 8-, or 15-day-old rats, 1S,3R-ACPD increased basal cAMP formation but failed to reduce the action of forskolin. A similar development pattern of modulation was observed in hypothalamic slices with the difference that 1S,3R-ACPD did not stimulate basal cAMP formation in the hypothalamus of adult animals. These results suggest that inhibition of forskolin-stimulated cAMP formation by 1S,3R-ACPD is mediated by a specific mGluR subtype that is preferentially expressed in the adult.

Aging↗
PubMed1992

Nootropic drugs positively modulate alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid-sensitive glutamate receptors in neuronal cultures.

Micromolar concentrations of piracetam, aniracetam, and oxiracetam enhanced alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)-stimulated 45Ca2+ influx in primary cultures of cerebellar granule cells. Nootropic drugs increased the efficacy but not the potency of AMPA and their action persisted in the presence of the voltage-sensitive calcium channel blocker nifedipine. Potentiation by oxiracetam was specific for AMPA receptor-mediated signal transduction, as the drug changed neither the stimulation of 45Ca2+ influx by kainate or N-methyl-D-aspartate nor the activation of inositol phospholipid hydrolysis elicited by quisqualate or (+-)-1-aminocyclopentane-trans-1,3-dicarboxylic acid. Piracetam, aniracetam, and oxiracetam increased the maximal density of the specific binding sites for [3H]AMPA in synaptic membranes from rat cerebral cortex. Taken collectively, these results support the view that nootropic drugs act as positive modulators of AMPA-sensitive glutamate receptors in neurons.

Animals↗
PubMed1992

Increased rate of survival in Streptococcus pneumoniae-infected rats treated with the new immunomodulator Pidotimod.

Wistar rats infected with Streptococcus pneumoniae (type III ATCC) rapidly develop an acute form of experimental lobar pneumonia (ELP) with death of 80-90% of the animals by 6 days after the infection. Prophylactic treatment of these animals with the novel immunomodulator Pidotimod, at the dose of 25 mg/kg bw, significantly increased their rate of survival as compared to the control group (50 vs. 90% respectively). Recovery from the infection appeared definitive since all the Pidotimod-treated survivors were alive and in good condition at the end of the observation period (45 days post infection). Prophylactic treatment with higher or lower doses of the drug was ineffective. Therapy with Pidotimod was not effective. This preliminary study suggests that Pidotimod may have contributed to activation of specific and non-specific immune effectors involved in the host response to S. pneumoniae infection.

Adjuvants, Immunologic↗
PubMed1992

Development profile of metabotropic glutamate receptor mRNA in rat brain.

We have studied the expression of metabotropic glutamate receptor (mGluR) mRNA by Northern blot analysis with a specific cDNA probe (the pmGR1 probe). In 1-day-old rats, the steady state levels of mRNA were higher in the hypothalamus and olfactory bulb, with intermediate levels in the cerebellum and low levels in the hippocampus and cerebral cortex. In the olfactory bulb, hypothalamus, and cerebral cortex, the expression of mGluR mRNA remained constant at 8 and 30 days of postnatal life. In contrast, in the cerebellum and hippocampus, mRNA levels increased progressively with age. There was no correlation between levels of mGluR mRNA and stimulation of polyphosphoinositide hydrolysis by 1-aminocyclopentane-1S,3R-dicarboxylic acid (trans-ACPD), which was much greater in brain slices from 8-day-old rats and was nearly absent in the adult cerebellum and olfactory bulb, where we have found the highest levels of mRNA. In addition, mGluR mRNA was detectable in cultured cerebellar granule cells but not in cultured neurons from cerebral hemispheres or in cultured astrocytes, which responded to trans-ACPD with an increased formation of [3H]inositol monophosphate. The discrepancies between levels of mGluR mRNA detected with the pmGR1 probe and trans-ACPD-stimulated polyphosphoinositide hydrolysis suggest either that different subtypes of mGluRs exist or that mRNA levels are not critical for the dynamic changes in the activity of mGluRs during development.

Aging↗