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Biomedical subjects

S Giordano

Publications and source records attributed to S Giordano.

At least 55 records · Page 3Linked to original sources
PubMed1998

Atopy in children with otitis media with effusion.

BACKGROUND: Contrasting data have been found on the prevalence of atopy in children with otitis media with effusion (OME). A major issue would be to determine whether screening for atopy should be recommended. Setting Centre for Study of Otitis Media with Effusion, Tabiano Terme, Parma, Italy. OBJECTIVE: The purpose of this study was to investigate the relation of OME to atopy. METHODS: The subjects were 172 children with OME and a control group of 200 children. The protocol included a questionnaire survey of diseases associated with atopy, a skin-prick test and a clinical evaluation of allergic symptoms and hypersensitivity to aeroallergens. RESULTS: No significant difference between patients and control group was observed for family history of atopy or positive skin-prick test reactions. Symptoms associated with atopy occurred significantly more frequently in the group with OME (P<0.001), though only the presence of rhinitis or atopic eczema was significantly associated with OME. CONCLUSIONS: Prevalence of positive skin-prick tests results is not enhanced in children with OME. Nevertheless, the association of OME with symptoms associated with atopy suggests that such concomitant diseases may play a part in the pathogenesis of the disorder. Children with allergic rhinitis or atopic eczema should be investigated by tympanometry for OME.

Acoustic Impedance Tests↗
PubMed1997

A point mutation in the MET oncogene abrogates metastasis without affecting transformation.

The MET oncogene encodes the tyrosine kinase receptor for hepatocyte growth factor/scatter factor (HGF), known to stimulate invasive growth of epithelial cells. MET is overexpressed in a significant percentage of human cancers and is amplified during the transition between primary tumors and metastasis. To investigate whether this oncogene is directly responsible for the acquisition of the metastatic phenotype, we exploited a single-hit oncogenic version of MET, able to transform and to confer invasive and metastatic properties to nontumorigenic cells, both in vitro and in nude mice. We mutagenized the signal transducer docking site of Met (Y1349VHVX3Y1356VNV), which has the uncommon property of binding and activating multiple src homology region 2 (SH2)-containing intracellular effectors. Notably, a point mutation (H1351 --> N) increased the transforming ability of the oncogene but abolished its metastatic potential. This mutation duplicates the Grb2 binding site, super-activating the Ras pathway and preventing the binding of the other intracellular transducers. Complementation in trans with another nonmetastatic mutant (N1358 --> H), recruiting all the transducers downstream to Met except Grb2, rescued the invasive-metastatic phenotype. It is concluded that the metastatic potential of the MET oncogene relies on the properties of its multifunctional docking site, and that a single point mutation affecting signal transduction can dissociate neoplastic transformation from metastasis.

Amino Acid Sequence↗
PubMed1997

A natural hepatocyte growth factor/scatter factor autocrine loop in myoblast cells and the effect of the constitutive Met kinase activation on myogenic differentiation.

As a rule, hepatocyte growth factor/scatter factor (HGF/SF) is produced by mesenchymal cells, while its receptor, the tyrosine kinase encoded by the met proto-oncogene, is expressed by the neighboring epithelial cells in a canonical paracrine fashion. In the present work we show that both HGF/SF and met are coexpressed by undifferentiated C2 mouse myoblasts. In growing cells, the autocrine loop is active as the receptor exhibits a constitutive phosphorylation on tyrosine that can be abrogated by exogenously added anti-HGF/SF neutralizing antibodies. The transcription of HGF/SF and met genes is downregulated when myoblasts stop proliferating and differentiate. The coexpression of HGF/SF and met genes is not exclusive to C2 cells since it has been assessed also in other myogenic cell lines and in mouse primary satellite cells, suggesting that HGF/SF could play a role in muscle development through an autocrine way. To analyze the biological effects of HGF/SF receptor activation, we stably expressed the constitutively activated receptor catalytic domain (p65(tpr-met)) in C2 cells. This active kinase determined profound changes in cell shape and inhibited myogenesis at both morphological and biochemical levels. Notably, a complete absence of muscle regulatory markers such as MyoD and myogenin was observed in p65(tpr-met) highly expressing C2 clones. We also studied the effects of the ectopic expression of human isoforms of met receptor (h-met) and of HGF/SF (h-HGF/SF) in stable transfected C2 cells. Single constitutive expression of h-met or h-HGF/SF does not alter substantially the growth and differentiation properties of the myoblast cells, probably because of a species-specific ligand-receptor interaction. A C2 clone expressing simultaneously both h-met and h-HGF/SF is able to grow in soft agar and shows a decrease in myogenic potential comparable to that promoted by p65(tpr-met) kinase. These data indicate that a met kinase signal released from differentiation-dependent control provides a negative stimulus for the onset of myogenic differentiation.

Animals↗
PubMed1997

Transgenic expression in the liver of truncated Met blocks apoptosis and permits immortalization of hepatocytes.

Hepatocyte growth factor induces proliferation, motility and differentiation of epithelial cells through the tyrosine kinase receptor encoded by the MET protooncogene. The cytoplasmic portion of Met (referred to as cyto-Met) is activated but only weakly transforming. In order to determine the effect of activated Met on hepatocytes, we have targeted truncated Met expression to the liver by incorporating the cDNA into a vector carrying the entire human alpha-1-antitrypsin transcriptional unit. Transgenic expression in the liver of truncated human Met, containing the regulatory and the catalytic cytoplasmic domains, renders hepatocytes constitutively resistant to apoptosis and reproducibly permits immortalization. The emerging stable cell lines are not transformed and maintain a highly differentiated phenotype judged by the retention of epithelial cell polarity and the expression of hepatocyte-enriched transcription factors as well as hepatic products.

Animals↗
PubMed1997

Molecular characterization of E587 antigen: an axonal recognition molecule expressed in the goldfish central nervous system.

The E587 antigen (Ag) is a 200-Kd membrane glycoprotein originally identified by a monoclonal antibody on new and regenerating retinal ganglion cell axons in the adult goldfish. We report the isolation of cDNAs encoding the E587 Ag and identify it as a member of the L1 family of cell adhesion molecules (CAMs). The predicted amino acid sequence of E587 Ag shows an approximately equal identity (40%) to mouse L1, chick neuron-glia CAM, and chick neuron-glia-related CAM. Although the overall similarity is low, there is a high conservation of structural domains and specific sequence motifs. Wholemount in situ hybridizations were performed on goldfish between 34 hours and 3 days postfertilization (pf). A dramatic increase in E587 Ag mRNA was observed between 34 and 48 hours pf. The expression of E587 Ag mRNA in neurons shortly precedes axonogenesis. A marked decrease in expression occurs by 3 days pf, when the axonal scaffold has already been established. Wholemount immunohistochemistry on embryos demonstrates expression of E587 Ag on all major tracts. E587 Ag is absent from mature retinal ganglion cell axons, but its expression is induced by optic nerve transection. A corresponding induction of E587 Ag mRNA in retinal ganglion cells is shown by in situ hybridization. Furthermore, E587 Ag mRNA was detected in the optic nerve, which suggests that nonneuronal cells also express this molecule. E587 Ag was previously shown to promote retinal axon fasciculation and outgrowth in young fish and to mediate axon-glial interactions in vitro. The expression pattern and developmental regulation of E587 Ag in the central nervous system, its reexpression in retinal ganglion cells following optic nerve transection, and its relation to the L1 family indicate that E587 Ag functions as a cell recognition molecule important during axonal growth and regeneration.

Amino Acid Sequence↗
PubMed1997

Expression of an L1-related cell adhesion molecule on developing CNS fiber tracts in zebrafish and its functional contribution to axon fasciculation.

E587 antigen, an L1-related cell adhesion molecule, is expressed by growing axons and has previously been shown to enhance axon growth and to mediate fasciculation of axons from newborn retinal ganglion cells in goldfish. In zebrafish, the monoclonal antibody E17 against E587 antigen stains all axons in the primary tracts and commissures from 17 h postfertilization (pf) onward and axons which are added subsequently to this scaffold. Moreover, Fab fragments of an E587 antiserum (E587 Fabs) injected into the ventricle of 30-h pf zebrafish embryos caused a marked defasciculation of distinct axon bundles in the posterior commissure, in hindbrain commissures, and in longitudinal tracts of the hindbrain, where they also caused increased crossings between fascicles. The regulated expression of E587 antigen by all developing axons and the effects caused by E587 Fabs show that E587 antigen contributes to the formation of tight and orderly fascicles in the developing CNS.

Animals↗
PubMed1997

Plasma levels of tumor necrosis factor-alpha and interferon-gamma in Sicilian children with Mediterranean spotted fever.

The plasma levels of tumor necrosis factor-alpha and interferon-gamma were measured in 53 consecutive children with serologically confirmed Mediterranean spotted fever and were found to be increased during the acute phase compared with the convalescent phase (tumor necrosis factor-alpha mean 32.17 vs. 4.12 pg/ml, P < 0.0001; interferon-gamma mean 84.17 vs. 2.65 pg/ml, P = 0.0006). Plasma levels of both cytokines were higher in patients with a typical exanthema rather than those with a very mild or no exanthema; tumor necrosis factor-alpha levels were significantly lower in the latter (tumor necrosis factor-alpha 32.17 vs. 9.85 pg/ml, P < 0.0001; interferon-gamma 84.17 vs. 38.14 pg/ml, P = 0.35). Tumor necrosis factor-alpha and interferon-gamma may be harmful or beneficial to the infected host, depending upon the amounts produced and whether they are circulating or confined locally to the site of inflammation.

Adolescent↗
PubMed1997

Epidemiologic surveillance of visceral leishmaniasis in Sicily, Italy.

Visceral leishmaniasis (VL) is endemic in Sicily. Although it is a notifiable disease, there is evidence that the actual number of cases is higher than that reported. In 1987, a regional reference center for active surveillance of VL was established and it recorded a total of 284 cases through 1995, a mean of 31.5 cases/year and about four-fold more than previously reported. Of the 284 cases, 150 (53%) were children (< or = 14 years of age), and of the 134 adults, 39 (29%) were coinfected with human immunodeficiency virus (HIV). The commonest viscerotropic zymodeme of Leishmania infantum, MON 1, was identified in 40 (93%) of 43 HIV-negative and eight (57%) of 14 HIV-positive patients. Among 280 patients evaluated (i.e., all HIV-negative and 35 of 39 HIV-positive subjects), 254 (91%) were treated with meglumine antimoniate alone or in combination with other drugs; 23 (8%) received allopurinol or amphotericin B, either conventional or in liposomal form; and three terminally ill patients were not treated. Among the 245 HIV-negative patients, 236 (96%) were successfully cured, while nine (4%) (seven adults) died during the course of antimonial treatment. None of the 35 HIV-positive patients was definitively cured, although mortality was apparently associated with other opportunistic infections.

Adolescent↗
PubMed1996

Ets up-regulates MET transcription.

MET, a potentially harmful oncogene controlling invasive growth, is overexpressed in a significant percentage of human cancers. Since amplification of the MET gene occurs only in a fraction of these cases, we investigated the transcriptional mechanisms responsible for up-regulation of the promoter activity. The transcription driven by the 3.1 kbp DNA fragment containing the minimal promoter was studied by 5' progressive deletion analysis. The patterns of MET promoter activity suggest the presence of weak negative and positive elements in the region between 300 and 840 bp upstream to the transcription start site. The region encompassing the first 300 bp strongly up-regulates the promoter. This region contains four putative binding sites for members of the Ets transcription factor family, known to be involved in invasive growth. Transient co-expression of Ets1 resulted in a strong enhancement of the MET promoter activity. Increased expression of the Met protein was observed in cells stably transfected with ETS1. Double stranded oligonucleotides with Ets consensus sequence were used as a 'decoy' to inhibit binding to DNA native sites. They dramatically reduced the amount of Met protein in a human carcinoma cell line overexpressing the oncogene. Interestingly, Met activation induces transcription of ETS1 mRNA, showing that Ets proteins act both upstream and downstream to MET. These data indicate that members of the Ets family promote MET transcription and suggest their contribution to the invasive phenotype through overexpression of MET.

Animals↗
PubMed1996

Specific uncoupling of GRB2 from the Met receptor. Differential effects on transformation and motility.

The biological effects of hepatocyte growth factor/scatter factor are mediated by autophosphorylation of its receptor, the Met tyrosine kinase, on two carboxyl-terminal tyrosines. These phosphotyrosines (Y1349VHVNATY1356VNV) are multifunctional docking sites for several effectors. Grb2, the adaptor for the Ras guanyl-nucleotide exchanger SOS, binds to Tyr1356 in the YVNV motif. By site-directed mutagenesis we either abrogated or duplicated the Grb2 consensus, without interfering with the other effectors. Loss of the link with Grb2 severely impaired transformation. The same mutation, however, had no effect on the "scattering" response, indicating that the level of signal which can be reached by Grb2-independent routes is permissive for motility. Duplication of the Grb2 binding site enhanced transformation and left motility unchanged. Thus, two Met-mediated biological responses, motility and growth, can be dissociated on the basis of their differential requirement for a direct link with Ras.

3T3 Cells↗
PubMed1996

Increased nasal eosinophils in children with otitis media with effusion.

The pathogenesis of otitis media with effusion is still under debate, but allergic sensitization has been suggested in some cases. We investigated whether nasal cytology may indicate an allergic pathogenesis for otitis media with effusion. Atopic symptoms, results of skin prick tests to common aeroallergens, and nasal cytology by nasal scraping were evaluated in 40 children with current otitis media with effusion and compared with findings in a group of 40 healthy children. The presence of nasal eosinophils was significantly more frequent in children with otitis media with effusion than in the control group (p < 0.05). Nasal eosinophils were significantly associated with both allergic rhinitis (p < 0.001) and positive skin prick test results (p < 0.001). Allergic rhinitis with nasal eosinophilia was found in six children of the study group and in one child of the control group (p < 0.05). Our data suggest that nasal allergic inflammation may play a role in a subset of patients with otitis media with effusion. Therefore the possibility of allergic sensitization must always be considered in patients with serous otitis media.

Child↗
PubMed1995

The motogenic and mitogenic responses to HGF are amplified by the Shc adaptor protein.

The receptor of Hepatocyte Growth Factor-Scatter Factor (HGF) is a tyrosine kinase which regulates cell motility and growth. After ligand-induced tyrosine phosphorylation, the HGF receptor associates with the Shc adaptor, via the SH2 domain. Site-directed mutagenesis of the HGF receptor indicates that phosphotyrosines Y1349VHV and Y1356VNV can work as docking sites for Shc. The Kd of this interaction, measured in real time using synthetic phosphopeptides and recombinant Shc on a BIAcore biosensor, is 150 nm for both sites. After stimulation of the HGF receptor, Shc is phosphorylated on Y317VNV, generating an high affinity binding site for Grb2 (Kd = 15 nM). This duplicates the high affinity binding site for Grb2 present on the HGF receptor (Y1356VNV). Thus HGF stimulation can trigger the Ras pathway by recruiting Grb2 both directly through the receptor, and indirectly, through Shc. Overexpression of wild-type Shc, but not of the Y317-->F mutant, enhances cell migration and growth in response to HGF. These data show that Shc is a relevant substrate of the HGF receptor, and works as an 'amplifier' of the motogenic as well as of the mitogenic response.

Adaptor Proteins, Signal Transducing↗
PubMed1995

Relationship between oral challenges with previously uningested egg and egg-specific IgE antibodies and skin prick tests in infants with food allergy.

BACKGROUND: Positive skin prick test (SPT) and RAST reactions to egg that had never previously been ingested have been observed in infants with food allergy. The likelihood of having clinical hypersensitivity reactions when egg is first ingested and the predictive value of SPT and RAST remain to be elucidated. OBJECTIVE: We investigated the relationship between egg-specific IgE antibodies and positive SPT reaction to egg, and the development of clinical hypersensitivity on the first exposure, in infants with food allergy. METHODS: The patient group consisted of 21 infants with food allergy and positive SPT and/or RAST reaction to egg, which they had never previously ingested; the control group of 12 infants had food allergy and negative test results. All subjects underwent double-blind placebo-controlled food challenges with egg. RESULTS: Thirteen of 21 patients (61%) and one of 12 control subjects (8%) had positive reactions to challenges (p < 0.01). Thirteen positive reactions to challenges (93%) elicited immediate symptoms. Late-onset eczema occurred in two children. SPT results showed a high sensitivity (0.92) and negative predictive accuracy (0.92), whereas specificity (0.57) and positive predictive accuracy (0.61) were poor. RAST did not have any diagnostic advantage over SPT. CONCLUSIONS: In infants with food allergy SPT with egg may be helpful in predicting which patients will react to the first exposure.

Child, Preschool↗
PubMed1995

L-propionylcarnitine effect on postexercise and postischemic hyperemia in patients affected by peripheral vascular disease.

The hemodynamic effect of L-propionylcarnitine (LPC) administered intravenously was evaluated in a double-blind, randomized, three-period crossover study in 12 men (aged sixty to seventy-five years) with Leriche-Fontaine stage II peripheral arterial disease of lower limbs. At baseline, maximum working capacity of each patient was determined by a standardized ergometric test. This test was repeated at 80% of each patient's maximum working capacity before and after intravenous administration of LPC. Each patient received three single doses of 300 mg, 600 mg, and 1200 mg of LPC with a two-day rest period between them. Hemodynamic variables measured by strain-gauge plethysmography were: peak blood flow, peak flow time, and halftime and total time of hyperemia both after exercise and after induction of ischemia (with an occlusion cuff). LPC administration significantly shortened the halftime as well as the total time of hyperemia after exercise and after ischemia. With the two highest doses, LPC shortened the peak flow time after exercise. The peak blood flow after exercise and after ischemia increased, but this increase did not reach statistical significance. The results obtained indicate that LPC improves circulatory reserve of the ischemic limb and has no effect on heart rate and arterial blood pressure. No adverse events were reported. The effect of LPC on the hyperemic response to stress, mainly on halftime of hyperemia, is possibly due to a drug-induced increase of adenosine triphosphate utilization by the ischemic tissues.

Aged↗
PubMed1995

Overexpression and amplification of the met/HGF receptor gene during the progression of colorectal cancer.

The c-met oncogene encodes the receptor for hepatocyte growth factor/scatter factor, a potent mitogen for epithelial cells that also promotes cell motility and invasiveness. We have studied the changes of c-met gene expression that occur during the progression of colorectal tumors. Sixteen adenomas, 123 primitive carcinomas, and 25 liver metastases were examined. In several instances it was possible to compare same-patient samples of normal colon mucosa against primary tumor and primary carcinoma against synchronous metastasis. The expression of the c-met gene was increased from 5- to 50-fold in about 50% of tumors, at any stage of progression, and in 70% of liver metastases. Overexpression was associated with amplification of the c-met gene in only 10% of carcinomas, but in 8 of 9 metastases examined. These data suggest that overexpression of the c-met oncogene contributes a selective growth advantage to neoplastic colorectal cells at any stage of tumor progression. Moreover, amplification appears to give a further selective advantage for the acquisition of metastatic potential.

Adenoma↗
PubMed1994

Structure and inducible regulation of the human MET promoter.

The MET oncogene, encoding the tyrosine kinase receptor for the hepatocyte growth factor/scatter factor, is expressed in epithelial cells and overexpressed in a significant proportion of human epithelial cancers, suggesting the occurrence of transcriptional alteration(s). To identify the MET promoter, we isolated recombinant cDNA clones encompassing the entire 5'-noncoding sequence of MET messenger RNAs. Using probes derived from this region, we cloned the entire genomic region spanning the first MET exon and the flanking regulatory sequences. The first exon, containing the entire untranslated sequence, is present in the MET mRNAs of 7.1, 5.9, and 4.6 kilobases, showing that the expression of the multiple transcripts is regulated by a single promoter. The start site of transcription was determined by primer extension and by rapid amplification of cDNA ends. We show that a 300-base pair fragment, containing sequences upstream from the start site, efficiently drives the expression of a reporter gene in transfected epithelial cells. This promoter fragment also contains the cis-acting elements responsible for phorbol-ester induction.

Base Sequence↗