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Biomedical subjects

A Riccio

Publications and source records attributed to A Riccio.

At least 37 records · Page 2Linked to original sources
PubMed1999

Mediation by a CREB family transcription factor of NGF-dependent survival of sympathetic neurons.

Nerve growth factor (NGF) and other neurotrophins support survival of neurons through processes that are incompletely understood. The transcription factor CREB is a critical mediator of NGF-dependent gene expression, but whether CREB family transcription factors regulate expression of genes that contribute to NGF-dependent survival of sympathetic neurons is unknown. CREB-mediated gene expression was both necessary for NGF-dependent survival and sufficient on its own to promote survival of sympathetic neurons. Moreover, expression of Bcl-2 was activated by NGF and other neurotrophins by a CREB-dependent transcriptional mechanism. Overexpression of Bcl-2 reduced the death-promoting effects of CREB inhibition. Together, these data support a model in which neurotrophins promote survival of neurons, in part through a mechanism involving CREB family transcription factor-dependent expression of genes encoding prosurvival factors.

Animals↗
PubMed1999

Role of histone acetylation and DNA methylation in the maintenance of the imprinted expression of the H19 and Igf2 genes.

H19 and Igf2 are linked and reciprocally imprinted genes. We demonstrate that the histones associated with the paternally inherited and unexpressed H19 allele are less acetylated than those associated with the maternal expressed allele. Cell growth in the presence of inhibitors of either histone deacetylase or DNA methylation activated the silent Igf2 allele, whereas derepression of the silent H19 allele required combined inhibition of DNA methylation and histone deacetylation. Our results indicate that histone acetylation as well as DNA methylation contribute to the somatic maintenance of H19 and Igf2 imprinting and that silencing of the imprinted alleles of these two genes is maintained via distinct mechanisms.

Acetylation↗
PubMed1999

MED1, a novel human methyl-CpG-binding endonuclease, interacts with DNA mismatch repair protein MLH1.

The DNA mismatch repair (MMR) is a specialized system, highly conserved throughout evolution, involved in the maintenance of genomic integrity. To identify novel human genes that may function in MMR, we employed the yeast interaction trap. Using the MMR protein MLH1 as bait, we cloned MED1. The MED1 protein forms a complex with MLH1, binds to methyl-CpG-containing DNA, has homology to bacterial DNA repair glycosylases/lyases, and displays endonuclease activity. Transfection of a MED1 mutant lacking the methyl-CpG-binding domain (MBD) is associated with microsatellite instability (MSI). These findings suggest that MED1 is a novel human DNA repair protein that may be involved in MMR and, as such, may be a candidate eukaryotic homologue of the bacterial MMR endonuclease, MutH. In addition, these results suggest that cytosine methylation may play a role in human DNA repair.

Adaptor Proteins, Signal Transducing↗
PubMed1999

Clinical and immunologic effects of a rush sublingual immunotherapy to Parietaria species: A double-blind, placebo-controlled trial.

BACKGROUND: The local (noninjection) routes of immunotherapy are presently regarded as viable therapeutic options for respiratory allergy, and their mechanisms of action are currently undergoing investigation. OBJECTIVE: We evaluated the clinical efficacy of a preseasonal rush sublingual-swallow immunotherapy and its effects on allergic inflammation in patients with seasonal rhinoconjunctivitis caused by Parietaria species. METHODS: Thirty patients with Parietaria species-induced rhinoconjunctivitis (13 with mild intermittent asthma) were randomly assigned sublingual-swallow immunotherapy or placebo in a rush preseasonal course. We assessed the seasonal symptom-drug intake score by diary card and the inflammatory infiltration and the intercellular adhesion molecule 1 expression on nasal epithelium after specific allergenic challenge before and after treatment. RESULTS: The investigated immunotherapy was well tolerated, and no side effects were recorded. A significant reduction of the symptom score (P =.016) and drug intake score (P =. 008) after immunotherapy was observed only in the active group. A decrease of the cumulative score was observed also in the placebo group (P =.046), but the significance was clearly higher (P =.006) in the active group. In the active group a reduction of neutrophils (P =.001), eosinophils (P =.01), and intercellular adhesion molecule 1 expression (P =.04) after specific nasal challenge was also detected. CONCLUSION: The present results suggest that this sublingual-swallow immunotherapy administered through a rush schedule is clinically effective and safe and that it decreases the immune-mediated inflammatory responses to the allergen.

Administration, Sublingual↗
PubMed1999

The Rhizobium etli metZ gene is essential for methionine biosynthesis and nodulation of Phaseolus vulgaris.

A mutant strain (CTNUX23) of Rhizobium etli carrying Tn5 unable to grow with sulfate as the sole sulfur source was isolated and characterized. Sequence analysis showed that Tn5 is inserted into a metZ (O-succinylhomoserine sulfhydrylase)-homologous gene. The CTNUX23 mutant strain had a growth dependency for methionine, although cystathionine or homocysteine, but not homoserine or O-succinylhomoserine, allowed growth of the mutant. RNase protection assays showed that the metZ-like gene had a basal level of expression in methionine- or cysteine-grown cells, which was induced when sulfate or thiosulfate was used. The metZ gene was cloned from the parent wild-type strain, CE3, and the resulting plasmid pAR204 relieved, after transformation, the methionine auxotrophy of both strains CTNUX23 of R. etli and PAO503(metZ) of Pseudomonas aeruginosa. Unlike strain CE3 or CTNUX23 (pAR204), strain CTNUX23 showed undetectable levels of O-succinylhomoserine sulfhydrylase activity. Strain CTNUX23 was unable to produce flavonoid-inducible lipo-chitin oligosaccharides (Nod factors) or to induce nodules or nodulelike structures on the roots of Phaseolus vulgaris, unless methionine was added to the growth medium. These data and our previous results support the notion that cysteine or glutathione, but not methionine, is supplied by the root cells to bacteria growing inside the plant.

Amino Acid Sequence↗
PubMed1999

The Rhizobium etli trpB gene is essential for an effective symbiotic interaction with Phaseolus vulgaris.

A mutant strain (CTNUX4) of Rhizobium etli carrying Tn5 unable to grow with ammonium as the sole nitrogen source was isolated and characterized. Sequence analysis showed that Tn5 is inserted into a trpB (tryptophan synthase)-homologous gene. When tested on the roots of Phaseolus vulgaris, strain CTNUX4 was able to induce only small, slightly pink, ineffective (Fix-) nodules. However, under free-living conditions, strain CTNUX4 was unable to produce flavonoid-inducible lipo-chitin oligosaccharides (Nod factors) unless tryptophan was added to the growth medium. These data and histological observations indicate that the lack of tryptophan biosynthesis affects the symbiotic behavior of R. etli.

Amino Acid Sequence↗
PubMed1998

Antiphospholipid antibodies bind to rat cerebellar granule cells: the role of N-methyl-D-aspartate receptors.

IgGs from sera containing antiphospholipid antibodies (aPL), detected as antibodies to cardiolipin, or control sera were incubated with rat cerebellar granule cells in primary culture. Using a mitochondrial dehydrogenase activity assay (MTT test), aPL IgGs were shown to decrease MTT metabolism after 24 h incubation with the cells, and to cause non-toxic amounts of glutamate to become neurotoxic when added to the cells for 45 min. Acute and chronic aPL toxicity were prevented by MK-801. Sera containing aPL bound to intact cerebellar neurons, as revealed by an immunofluorescent technique. These results suggest that antiphospholipid antibodies interfere with excitatory pathways in glutamatergic cerebellar granule cells by a mechanism involving overactivation of the NMDA glutamate receptor.

Animals↗
PubMed1998

5D4 keratan sulfate epitope identifies a subset of ramified microglia in normal central nervous system parenchyma.

Microglia expressing keratan sulfate (KS) was studied in normal central nervous system (CNS) and in rat neonatal brain cultures. The majority of KS+ cells are ramified microglia located in the brain parenchyma; positive cells were only exceptionally found in extraparenchymal structures. KS+ cells are ubiquitous, but their density is heterogeneous throughout the CNS. Serial sections incubated with anti-KS MAb and MAb against the complement receptor type 3 (CR3) revealed a higher number of CR3+ cells and double immunofluorescence showed the presence of two microglial populations: the first expressing both KS and CR3, the second expressing only CR3. Two sets of microglial cells were found also in neonatal rat microglial cultures where only a low percentage of microglial cells expressing CR3 was also KS+. KS was not induced by microglia activation.

Animals↗
PubMed1998

Randomised controlled trial of local allergoid immunotherapy on allergic inflammation in mite-induced rhinoconjunctivitis.

BACKGROUND: Non-injective routes of immunotherapy are thought to be valuable therapeutic options for respiratory allergy. We investigated the clinical efficacy and the effects of sublingual/oral immunotherapy on conjunctival allergic inflammation in patients with mite-induced respiratory allergy. METHODS: We used a double-blind placebo-controlled design. 20 patients with mite-induced rhinoconjunctivitis (six of whom also had mild asthma) were randomly assigned sublingual/oral immunotherapy (n=10) or placebo (n=10) for 2 years. We assessed symptom score by diary cards and inflammatory-cell infiltrate, and expression of intercellular adhesion molecule 1 (ICAM-1) in the conjunctiva after specific allergen challenge at enrollment and after 12 and 24 months of treatment. FINDINGS: We found significantly lower symptom scores in the immunotherapy group than in the placebo group in most of the winter months (p=0.05). Compared with the placebo group, inflammatory-cell infiltration after conjunctival challenge, and ICAM-1 expression on conjunctival epithelium decreased significantly in the first year of treatment in the immunotherapy group (p=0.04 and p=0.02, respectively). These effects were also seen for the minimum persistent inflammation, in symptom-free patients exposed constantly to allergens (p=0.02). Serum concentrations of eosinophil cationic protein decreased significantly (p=0.04). Immunotherapy was well tolerated and compliance was good. INTERPRETATION: Our results suggest that this immunotherapy is clinically effective in rhinoconjunctivitis and that it decreases the immune-mediated inflammatory responses to the allergen.

Administration, Sublingual↗
PubMed1998

Binding of a substrate analog to a domain swapping protein: X-ray structure of the complex of bovine seminal ribonuclease with uridylyl(2',5')adenosine.

Bovine seminal ribonuclease (BS-RNase) is a unique member of the pancreatic-like ribonuclease superfamily. The native enzyme is a mixture of two dimeric forms with distinct structural features. The most abundant form is characterized by the swapping of N-terminal fragments. In this paper, the crystal structure of the complex between the swapping dimer and uridylyl(2',5')adenosine is reported at 2.06 A resolution. The refined model has a crystallographic R-factor of 0.184 and good stereochemistry. The quality of the electron density maps enables the structure of both the inhibitor and active site residues to be unambiguously determined. The overall architecture of the active site is similar to that of RNase A. The dinucleotide adopts an extended conformation with the pyrimidine and purine base interacting with Thr45 and Asn71, respectively. Several residues (Gln11, His12, Lys41, His119, and Phe120) bind the oxygens of the phosphate group. The structural similarity of the active sites of BS-RNase and RNase A includes some specific water molecules believed to be relevant to catalytic activity. Upon binding of the dinucleotide, small but significant modifications of the tertiary and quaternary structure of the protein are observed. The ensuing correlation of these modifications with the catalytic activity of the enzyme is discussed.

Animals↗
PubMed1998

Chronic post-traumatic headache associated with minor cranial trauma: a description of cephalalgic patterns.

We studied a group of 93 patients who had not previously suffered headache and who were consecutively admitted to the Emergency Department of the hospitals of Novara and Borgomanero, Italy because of a cranial trauma definable as minor according to the current International Headache Society (IHS) criteria. Two weeks after admission, all patients underwent a semi-structured interview which revealed that 24 (25.8%) had headache; 21 of these (22.5% of the original 93 patients) also had headache when they underwent a second interview eight weeks after the traumatic event. These 21 patients were diagnosed as having chronic post-traumatic headache associated with minor cranial trauma (5.2.2 of the IHS classification), and the prevalent clinical pattern of headache presentation was examined with the aim of attributing the fourth IHS classification code number. Eighteen of the 21 patients were found to have a tension-type pattern (5.2.2.2), and the remaining three had migraine (5.2.2.1); none had cluster headache (5.2.2.3). These data demonstrate a large prevalence of tension-type headache in patients with class 5.2.2 post-traumatic headache, and confirm the results of previously published studies that were not based on the diagnostic criteria of the current classification.

Adult↗
PubMed1998

Expression of GM-CSF receptor and "in vitro" effects of GM-CSF on human fibroblasts.

In the present study the effects of Granulocyte-Macrophage Colony Stimulating Factor (GM-CSF) on fibroblast growth and activity have been studied. In this regard the AA have evaluated in primary cultures of human gengival normal fibroblasts (PG1 cells): a)-the expression of GM-CSF receptor (GM-CSFR) (alfa unit) on the cell surface; b)-the in vitro effects of different doses of GM-CSF on the GM-CSFR expression and on the proliferation and activity of fibroblasts. PG1 cells have been stimulated in vitro with different concentrations of GM-CSF (10, 50, 80, 100 and 150 ng/ml) using promonocytic cell line U937 as positive control for GM-CSFR expression. GM-CSFR was investigated by flow cytometry, with mouse monoclonal antibody (mAb) against the alfa chain of the human GM-CSFR and fluorescein-conjugated goat antimouse immunoglobulin G (IgG). At high GM-CSF concentration (80 ng/ml) the AA observed: 1)-A marked increase of GM-CSFR expression evaluated as fluorescence intensity (about three fold in respect to the controls); 2)-Maximal increase of PG1 cells proliferation. Moreover immunofluorescence on fibroblasts obtained from culture plates showed increased actin stress fibers and fibronectin production with low stimulation by GM-CSF, while higher concentration of this cytokine determined increased proliferation of cells, but a decreased formation of actine fibers and vinculin plaques. These results demonstrate: 1)-The presence of GM-CSFR on the surface of fibroblasts; 2)-The proliferation and the synthesis activity of these cells (in vitro) are modulated by different concentration of GM-CSF. We hypothesize that GM-CSF until 80 ng/ml can upregulate the expression of the receptor. Therefore, on the basis of previous findings of high serum levels of GM-CSF in course of scleroderma, a disease characterized by fibroblast hyperactivity, a possible role of this cytokine in the pathogenic process of this disease can be hypothesized.

Animals↗
PubMed1998

Identification and characterization of novel substrates of Trk receptors in developing neurons.

Neurotrophins influence growth and survival of specific populations of neurons through activation of Trks, members of the receptor tyrosine kinase (RTK) family. In this report, we describe the identification and characterization of two substrates of Trk kinases, rAPS and SH2-B, which are closely related Src homolog 2 (SH2) domain-containing signaling molecules. rAPS and SH2-B are substrates of TrkB and TrkC in cortical neurons and SH2-B is a substrate of TrkA in sympathetic neurons. Moreover, rAPS and SH2-B bind to Grb2, and both are sufficient to mediate NGF induction of Ras, MAP kinase (MAPK), and morphological differentiation of PC12 cells. Lastly, antibody perturbation and transient transfection experiments indicate that SH2-B, or a closely related molecule, is necessary for NGF-dependent signaling in neonatal sympathetic neurons. Together, these observations indicate that rAPS and SH2-B mediate Trk signaling in developing neurons.

Adaptor Proteins, Signal Transducing↗
PubMed1998

The Rhizobium etli amtB gene coding for an NH4+ transporter is down-regulated early during bacteroid differentiation.

During development of root nodules, Rhizobium bacteria differentiate inside the invaded plant cells into N2-fixing bacteroids. Terminally differentiated bacteroids are unable to grow using the ammonia (NH3) produced therein by the nitrogenase complex. Therefore, the nitrogen assimilation activities of bacteroids, including the ammonium (NH4+) uptake activity, are expected to be repressed during symbiosis. By sequence homology the R. etli amtB (ammonium transport) gene was cloned and sequenced. As previously shown for its counterpart in other organisms, the R. etli amtB gene product mediates the transport of NH4+. The amtB gene is cotranscribed with the glnK gene (coding for a PII-like protein) from a nitrogen-regulated sigma 54-dependent promoter, which requires the transcriptional activator NtrC. Expression of the glnKamtB operon was found to be activated under nitrogen-limiting, free-living conditions, but down-regulated just when bacteria are released from the infection threads and before transcription of the nitrogenase genes. Our data suggest that the uncoupling between N2-fixation and NH3 assimilation observed in symbiosomes is generated by a transcriptional regulatory mechanism(s) beginning with the inactivation of NtrC in younger bacteroids.

Amino Acid Sequence↗
PubMed1997

Relaxation of insulin-like growth factor-2 imprinting in rat cultured cells.

The parental-specific expression of the insulin-like growth factor-2 (Igf-2) and H19 genes was studied in rat fibroblast cells derived from a 3 day-old first-generation hybrid animal obtained by crossing Fisher and Wistar strains (F x W cells). Results showed that the reciprocal imprinting of the Igf-2 and H19 genes was conserved in the rat tissues and in the derived F x W cells when cultured with frequent transfer. Igf-2 and H19 gene expression was coordinately up-regulated upon reaching confluence, but Igf-2 RNA levels were further increased in a time-dependent manner and the repressed state of the maternal Igf-2 allele was progressively relaxed in cultures held in the confluent state and in the presence of low serum for more than 3 days. The active expression and relaxed imprinting status of the Igf-2 gene persisted over cell generations when the growth-constraining conditions were released by trypsinization and dilution. On the contrary, the imprinting of the H19 gene appeared to be unaffected by changes in growth conditions and its expression was down-regulated when the confluent cells were passaged. Methylation of the H19 promoter and Igf-2 coding regions was increased in the F x W cells extensively held under confluence and in the derived 'post-confluent' cultures. The heritable changes in the expression, and imprinting status of the Igf-2 and H19 genes observed in the F x W cells closely resembles events described in human embryonal cancers and cancer-predisposing syndromes. The occurrence of imprinting relaxation under strong growth-inhibitory conditions supports the hypothesis that it is an epigenetic change.

Animals↗
PubMed1997

An NGF-TrkA-mediated retrograde signal to transcription factor CREB in sympathetic neurons.

Nerve growth factor (NGF) is a neurotrophic factor secreted by cells that are the targets of innervation of sympathetic and some sensory neurons. However, the mechanism by which the NGF signal is propagated from the axon terminal to the cell body, which can be more than 1 meter away, to influence biochemical events critical for growth and survival of neurons has remained unclear. An NGF-mediated signal transmitted from the terminals and distal axons of cultured rat sympathetic neurons to their nuclei regulated phosphorylation of the transcription factor CREB (cyclic adenosine monophosphate response element-binding protein). Internalization of NGF and its receptor tyrosine kinase TrkA, and their transport to the cell body, were required for transmission of this signal. The tyrosine kinase activity of TrkA was required to maintain it in an autophosphorylated state upon its arrival in the cell body and for propagation of the signal to CREB within neuronal nuclei. Thus, an NGF-TrkA complex is a messenger that delivers the NGF signal from axon terminals to cell bodies of sympathetic neurons.

Animals↗
PubMed1997

Cloning and transcriptional analysis of the lipA (lipoic acid synthetase) gene from Rhizobium etli.

We report here the isolation of a Rhizobium etli gene involved in lipoic acid metabolism, the lipA gene, which complements a lipA mutant strain of Escherichia coli. A promoter region (lipAp) was mapped immediately upstream of lipA and two in vivo transcription initiation sites were identified, preceded by sequences showing some homology to the -10/-35 promoter consensus sequences. The activity of the lipAp was found not to be regulated either by the carbon source or by the addition of lipoic acid. Moreover, quantitative analysis of the lipA transcript by RNase protection assays indicated its down-regulation during entry into stationary phase.

Amino Acid Sequence↗