Anaphylaxis induced by exercise and related to multiple food intake

In some patients, exercise-induced anaphylactic (EIAn) reactions occur only when a particular food is eaten before exercise. We describe three patients with EIAn induced by different foods. Patients who presented episodes of EIAn performed exercise challenges after fasting and 1 hour after a meal without foods suspected of predisposing the reaction. Subsequently, patients performed exercises after separate intake of each suspected food. Patients underwent skin prick tests (SPT) with food extracts. Serum total and specific IgE antibodies to food were determined. No reactions were provoked by exercise tests without prior intake of suspected foods. Eight of 30 food-exercise combination challenges were positive. In Patient 1, tomato, zucchini, and wheat resulted in adverse reactions: in Patient 2, potato, peanuts, and tomato; in Patient 3, rice and peanuts. SPTs and RASTs to foods predisposing the reaction were positive. Food-exercise combined challenge may be useful in identifying foods that favor EIAn in children with multiple food-dependent EIAn.

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.

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.

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.

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.

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.

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.

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.

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.

[Hydronephrosis associated with elevated serum levels of CA 125 antigen. Report of a case]

High level of the CA 125 serum antigen is typically associated with ovarian malignancies. However the CA 125 antigen can also be found in association with inflammation or neoplasms of tissues other than ovaries, i.e. mesothelial cells, mullerian duct derivatives and gastroenteric tract. Therefore the marker is not specific for ovarian neoplasms. In childhood there is not a large experience about clinical meaning of high CA 125 serum levels. We report a case in a 14-year-old patient, female, affected by hydronephrosis. Our case confirms that high CA 125, especially in childhood, is not necessarily associated with ovarian or pelvic diseases. Moreover the review of literature suggests the opportunity to investigate CA 125 serum levels in children affected by hydronephrosis.

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.

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.

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.

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.

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.

Cloning of multiple forms of goldfish vimentin: differential expression in CNS

In efforts to determine the primary structure of intermediate filament proteins in the goldfish visual pathway, we isolated clones from a retinal lambda gt11 cDNA expression library that represent goldfish vimentin. We show that there are at least two forms of goldfish vimentin, designated as vimentin alpha and vimentin beta. RNase protection assays indicate that vimentin alpha mRNA is expressed in low amounts in retina, optic nerve, and brain and in higher amounts in spinal cord. In contrast, vimentin beta mRNA is expressed in low amounts in retina, optic nerve, brain, and spinal cord and in very high amounts in eye lens. Immunohistochemical studies show that in the optic nerve, vimentin alpha is mainly restricted to blood vessels, meninges, and septa. Light staining is observed with this antibody in an astrocytic glial pattern throughout the optic nerve. Two-dimensional gel analysis shows that all of these goldfish vimentins are low abundant components of optic nerve cytoskeletal preparations.

Structural and functional domains critical for constitutive activation of the HGF-receptor (Met)

The MET gene, encoding the tyrosine kinase receptor for Hepatocyte Growth Factor, is a potentially harmful oncogene overexpressed in a significant fraction of human cancers. To study the molecular mechanisms responsible for oncogenic activation, the biochemical and biological properties of a number of MET constructs were analysed. The native heterodimeric receptor (alpha beta), the beta chain alone, as well as a kinase defective mutant did not transform rodent fibroblasts upon transfection. The cytoplasmic domain, truncated immediately below the transmembrane region, acquired constitutive tyrosine kinase activity in vivo, produced foci of transformation, and was tumorigenic in nude mice. Removal of the first 39 amino acids of the juxtamembrane domain resulted in loss of constitutive activation in vivo and transforming potential, without impairment of the in vitro kinase activity. Replacement of the juxtamembrane domain with 5' TPR sequences restored constitutive kinase activation and transforming properties. Site-directed mutagenesis of either of the two tyrosine residues involved in the positive regulation of the catalytic activity upon phosphorylation (Y1234 or Y1235 in the kinase domain of the HGF receptor), strongly impaired TRP-MET transforming potential. These data show that: (1) the truncated cytoplasmic HGF receptor has constitutive kinase activity and is oncogenic; (2) the first 39 amino acids of the juxtamembrane domain and (3) the regulatory tyrosines in the catalytic domain are required to unleash its transforming potential.

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.

A multifunctional docking site mediates signaling and transformation by the hepatocyte growth factor/scatter factor receptor family

Signaling by tyrosine kinase receptors is mediated by selective interactions between individual Src homology 2 (SH2) domains of cytoplasmic effectors and specific phosphotyrosine residues in the activated receptor. Here, we report the existence in the hepatocyte growth factor/scatter factor (HGF/SF) receptor of a multifunctional docking site made of the tandemly arranged degenerate sequence YVH/NV. Phosphorylation of this site mediates intermediate- to high-affinity interactions with multiple SH2-containing signal transducers, including phosphatidylinositol 3-kinase, phospholipase C gamma, pp60c-src, and the GRB-2-Sos complex. Mutation of the two tyrosines results in loss of biological function, as shown by abrogation of the transforming activity in the oncogenic counterpart of the receptor. The same bidentate motif is conserved in the evolutionarily related receptors Sea and Ron, suggesting that in all members of the HGF/SF receptor family, signal transduction is channeled through a multifunctional binding site.

Molecular characterization of fish neurolin: a growth-associated cell surface protein and member of the immunoglobulin superfamily in the fish retinotectal system with similarities to chick protein DM-GRASP/SC-1/BEN

We have used the polymerase chain reaction to isolate cDNAs coding for goldfish and zebrafish neurolin, a previously identified 86 kDa cell surface glycoprotein in the goldfish visual system. Sequence analysis demonstrates that neurolin belongs to the immunoglobulin superfamily and is 51% similar to the chick cell adhesion molecule DM-GRASP, SC-1, BEN. Northern analysis with a riboprobe coding for the C-terminus of neurolin detected two mRNAs of 3.7 kb and 3.3 kb in both embryonic and adult goldfish. Several monoclonal and polyclonal antibodies were generated against immunopurified goldfish neurolin and two are shown to crossreact with zebrafish proteins. Both antibodies identify a zebrafish protein of the same molecular weight as goldfish neurolin on immunoblots. Immunohistochemical studies with these antibodies in the zebrafish retinotectal system demonstrate labeling on young ganglion cells and growing retinal axons in a pattern similar to that found in goldfish. The similarity of neurolin to a known cell adhesion molecule, its expression on developing retinal ganglion cells and axons in both embryos and adult fish, and its re-expression during retinal axon regeneration in the goldfish suggests that neurolin is important during axonal growth in the fish central nervous system.

Effects of defibrotide on physical performance and hemorheologic picture in patients with peripheral arteriopathy

In a random double-blind study versus placebo, 60 ambulatory patients with peripheral occlusive disease of the lower limbs and claudicatio intermittens (Leriche's stage 2), were treated for 60 days with defibrotide (400 mg b.i.d., oral, n = 30) or placebo (n = 30). Patients in the defibrotide group received additional treatment with the same drug at the reduced rate of 400 mg once daily for another 120 days for maintenance (total treatment duration 180 days). All patients were assessed at intake and 60 days for relative and absolute walking distance (RWD and AWD) in a standard treadmill test and for the Winsor Index (WI) at rest and after exercise; patients of the defibrotide treatment group were retested in the same way at 90-180 days. In a subgroup of patients (defibrotide = 11, placebo = 12), blood samples were obtained for the assessment of whole blood and plasma viscosity at intake and after 60 days of treatment. These samples could not be collected properly in the remaining cases, for technical reasons. At day 60, we compared the effects of the two treatments on physical performance: mean (SE) values of RWD were for defibrotide 148 (9.7) and 179 (12.4) m in basal and post-treatment conditions, respectively, and 209 (16.2) and 212 (17.1) m for placebo. Similar changes were observed for AWD: for defibrotide 206 (13.4) and 241 (15.2) m and for placebo 270 (22.9) and 272 (23.1) m. The mean changes were significantly larger with defibrotide: for RWD + 33 (7.1) vs. + 0.3 (3.8) m (p < 0.01) and for AWD + 34 (9.2) and -2 (6.6) m (p < 0.01). The overall gain of walking distance after maintenance therapy with the reduced defibrotide dosage amounted to approximately + 50% over basal (after 180 days). Blood and plasma viscosity improved in patients on defibrotide but the change fell short of statistical significance versus placebo. All findings confirm the potential usefulness of defibrotide in the treatment of peripheral arterial disease, at the same time encouraging further studies of the involved mechanisms of action.

Generation of a truncated hepatocyte growth factor receptor in the endoplasmic reticulum

The hepatocyte growth factor (HGF) receptor (p190MET) is a tyrosine kinase composed of two disulfide-linked chains, alpha of 50 kDa and beta of 145 kDa. We have previously described an isoform (p140MET) containing a beta chain of 85 kDa, lacking the cytoplasmic kinase domain. The two receptor variants originate by post-translational processing of a common single-chain precursor of 170 kDa (Pr170). In the endoplasmic reticulum a fraction of Pr170 is cleaved at the cytosolic side generating an intermediate product of 120 kDa (Pr120). This molecule 1) is already detectable after 15 min of pulse labeling, 2) contains high mannose-branched oligosaccharides, and 3) accumulates upon treatments inhibiting the export from the endoplasmic reticulum. A second cleavage, occurring after 30 min of chase in the trans-Golgi network, converts the single-chain precursors Pr170 and Pr120 into the mature heterodimers p190MET and p140MET. This process is inhibited by brefeldin A treatment. Conditions leading to Pr170 accumulation in the endoplasmic reticulum, such as receptor overexpression, induce kinase activation and overproduction of Pr120. Conversely, cells expressing a kinase-defective HGF receptor lack the truncated isoform. The proteolytic cleavage of the cytoplasmic domain may thus represent a safety mechanism aimed at preventing ligand-independent intracellular activation of the HGF receptor kinase.

Basic fibroblast growth factor expression is required for clonogenic growth of human glioma cells

Basic fibroblast growth factor (bFGF) is a heparin-binding protein, expressing potent mitogenic and angiogenic properties. Elevated levels of bFGF have been identified in human gliomas and glioma cell lines, suggesting that bFGF expression is involved in the aberrant growth patterns associated with these tumors. In the present study, the influence of bFGF on additional parameters of glioma cell malignancy was evaluated utilizing three distinct methods to suppress bFGF expression or activity including antisense oligonucleotide primers, a neutralizing monoclonal antibody or an inhibitor of the agonist action of bFGF: (1) The addition of 30 microM bFGF-specific antisense oligonucleotide primer to the human glioma cell line SNB-19 resulted in a 55% inhibition in colony formation in soft agar. This effect was dose-dependent and specific, as sense strand primer was ineffective in suppressing growth. In addition to exhibiting fewer colonies, antisense treatment significantly altered colony morphology. (2) SNB-19 cell growth in culture was suppressed in the presence of a neutralizing bFGF-specific monoclonal antibody. (3) Inositolhexakisphosphate, a newly identified antagonist of FGF binding and activity, suppressed SNB-19 cell growth in soft agar culture. These results demonstrate that bFGF may regulate glioma growth and progression independent of its role in tumor angiogenesis and that bFGF release or secretion may be required for these actions.

Transfer of motogenic and invasive response to scatter factor/hepatocyte growth factor by transfection of human MET protooncogene

The MET protooncogene encodes p190MET, a tyrosine kinase which is the receptor for a molecule known as scatter factor or hepatocyte growth factor (SF/HGF). This molecule has different biological activities, including stimulation of cell motility, promotion of matrix invasion and, in some cells, mitogenesis. We have cloned the full-length MET cDNA and transfected it into NIH 3T3 fibroblasts. Stable transfectants expressed the p190MET receptor together with two previously described truncated forms of 140 and 130 kDa lacking the tyrosine kinase domain. All three forms bound radiolabeled SF/HGF. The factor stimulated tyrosine kinase activity of the transfected p190MET and induced changes in cell shape, migration in Boyden chambers, and invasion of collagen matrices in vitro. The motile and invasive phenotype was transient and strictly dependent on the presence of SF/HGF. The factor did not stimulate either cell growth or thymidine incorporation in transfected cells, while it promoted colony formation in soft agar in the presence of 5% fetal calf serum. These data show that, in the presence of its ligand, the MET receptor expressed in fibroblasts induces cells to pursue a motogenic-invasive rather than a proliferative program.

Karyotypic analysis of gastric carcinoma cell lines carrying an amplified c-met oncogene

MKN 45 is a poorly differentiated gastric carcinoma cell line from which the subclone GTL 16 was obtained. Both lines carry an amplification unit derived from chromosome 7 sequences and containing an activated c-met oncogene. Karyotypic analysis showed that GTL 16 derived from a subclone of MKN 45 after endoreduplication. Several clonal abnormalities are evident in both lines; some are frequently observed in gastrointestinal tumors (loss of 17p and monosomy 18). Other consistent anomalies include 6q-, t(8;10) and t(5;8), and inv(16). A marker chromosome (M1), which was previously shown to contain the c-met amplification unit, is constantly duplicated in all GTL 16 metaphases; in contrast, most unidentified markers are retained in only a single copy in GTL 16 cells. These data are in agreement with the hypothesis that the c-met oncogene activation in these gastric cancer cell lines might be related to a gene dosage effect.

Limb anomalies following chorionic villus sampling: a registry based case-control study

Using data from the Italian Multicentric Birth Defect Registry a case-control study was performed to verify if chorionic villus sampling (CVS) was associated with transverse limb defects (TLD), with or without features of oro-mandibular-limb hypogenesis complex (OMLHC), in the exposed offspring. The results show that the risk of TLD and OMLHC is increased following CVS, and is particularly high for CVS performed early in pregnancy, i.e., under 70 days of gestational age. These results, together with a review of other epidemiologic studies, biological data and clinical reports, strongly suggest a causative role of CVS as a risk factor for TLD and indicate that at this stage CVS before 70 days of gestational age should be discouraged as an option for prenatal diagnosis and that all patients wishing to undergo CVS should be informed about the possible risk of the procedure.

Pharmacokinetics of two oral liquid formulations of oxatomide in children

A study on the pharmacokinetics of two suspensions of oxatomide at the concentrations of 25 and 2.5 mg/ml was carried out on 12 children (7M, 5F) with a mean age of 9 years and weight of 29 kg. The plasmatic concentration peak, the time to reach the peak and the area under the curve displayed no significant differences between the two formulations. The maximum concentrations and the peak time of oxatomide in children are similar to those observed in adults.

Multiple molecular weight forms of basic fibroblast growth factor are developmentally regulated in the central nervous system

Basic fibroblast growth factor (bFGF) is a heparin-binding protein implicated in the differentiation, proliferation, and maintenance of cells in the central nervous system (CNS). It is not clear how bFGF achieves this multiplicity of effects. Multiple molecular weight forms of bFGF have recently been identified, however, and each form may have distinct activities during CNS development. We have examined the pattern of bFGF expression during CNS development using protein immunoblot and RNA blot analyses. RNA blot analysis detected a major bFGF transcript of 3.7 kb in embryonic and adult rat brain; however, this message decreased in abundance during development. Three bFGF protein forms were identified on immunoblots of adult rat brain extract with approximate molecular weights of 18, 21, and 22 kDa. Embryonic rat brain extracts also contained the 18- and 21-kDa bFGF protein forms, but lacked the 22-kDa form. Expression of the 22-kDa form was first detected in the neonate and then steadily increased to adult levels by 1 month of age. Immunoblots of adult human brain extracts also showed the presence of three bFGF protein forms with approximate molecular weights of 18, 22, and 24 kDa. In human second trimester fetal brain extracts, only the 18-kDa bFGF protein was detected. Comparison of bFGF proteins in developing rat spinal cord, cerebellum, and cortex demonstrated that distinct patterns of bFGF protein forms exist in different regions of the CNS. Therefore, the expression of individual bFGF protein forms is regulated in the CNS with regard to both developmental stage and location. These data support the idea that different forms of bFGF may be associated with specific developmental events during the maturation and organization of the nervous system.

C-terminal truncated forms of Met, the hepatocyte growth factor receptor

The MET proto-oncogene encodes a transmembrane tyrosine kinase of 190 kDa (p190MET), which has recently been identified as the receptor for hepatocyte growth factor/scatter factor. p190MET is a heterodimer composed of two disulfide-linked chains of 50 kDa (p50 alpha) and 145 kDa (p145 beta). We have produced four different monoclonal antibodies that are specific for the extracellular domain of the Met receptor. These antibodies immunoprecipitate with p190MET two additional Met proteins of 140 and 130 kDa. The first protein (p140MET) is membrane bound and is composed of an alpha chain (p50 alpha) and an 85-kDa C-terminal truncated beta chain (p85 beta). The second protein (p130MET) is released in the culture supernatant and consists of an alpha chain (p50 alpha) and a 75-kDa C-terminal truncated beta chain (p75 beta). Both truncated forms lack the tyrosine kinase domain. p140MET and p130MET are consistently detected in vivo, together with p190MET, in different cell lines or their culture supernatants. p140MET is preferentially localized at the cell surface, where it is present in roughly half the amount of p190MET. The two C-terminal truncated forms of the Met receptor are also found in stable transfectants expressing the full-length MET cDNA, thus showing that they originate from posttranslational proteolysis. This process is regulated by protein kinase C activation. Together, these data suggest that the production of the C-terminal truncated Met forms may have a physiological role in modulating the Met receptor function.

Defective posttranslational processing activates the tyrosine kinase encoded by the MET proto-oncogene (hepatocyte growth factor receptor)

The MET proto-oncogene encodes a 190-kDa disulfide-linked heterodimeric receptor (p190 alpha beta) whose tyrosine kinase activity is triggered by the hepatocyte growth factor. The mature receptor is made of two subunits: an alpha chain of 50 kDa and a beta chain of 145 kDa, arising from proteolytic cleavage of a single-chain precursor of 170 kDa (pr170). In a colon carcinoma cell line (LoVo), the precursor is not cleaved and the Met protein is exposed at the cell surface as a single-chain polypeptide of 190 kDa (p190NC). The expression of the uncleaved Met protein is due to defective posttranslational processing, since in this cell line (i) the proteolytic cleavage site Lys-303-Arg-Lys-Lys-Arg-Ser-308 is present in the precursor, (ii) p190NC is sensitive to mild trypsin digestion of the cell surface, generating alpha and beta chains of the correct size, and (iii) the 205-kDa insulin receptor precursor is not cleaved as well. p190NC is a functional tyrosine kinase in vitro and is activated in vivo, as shown by constitutive autophosphorylation on tyrosine. The MET gene is neither amplified nor rearranged in LoVo cells. Overlapping cDNA clones selected from a library derived from LoVo mRNA were sequenced. No mutations were present in the MET-coding region. These data indicate that the tyrosine kinase encoded by the MET proto-oncogene can be activated as a consequence of a posttranslational defect.

Expression of the Met/HGF receptor in normal and neoplastic human tissues

The MET oncogene encodes a transmembrane tyrosine kinase receptor. Recently, hepatocyte growth factor (HGF), a potent growth factor for hepatocytes involved in liver regeneration, has been proposed as a ligand. In this paper, the physiological role of the human Met/HGF receptor is investigated by studying its specific distribution in normal and neoplastic tissues. Northern blot analysis has shown that the MET gene is selectively expressed in several epithelial tissues. High levels of MET mRNA have been found in liver, gastrointestinal tract, thyroid and kidney. Western blot analysis has shown that the levels of the Met protein generally correspond to those of the mRNA. However, in the thyroid, where there is a high level of MET mRNA, the protein was barely detectable, suggesting translational or post-translational regulation. The protein was also detected in the brain. Normal or increased levels of MET mRNA and Met protein were consistently found in fresh samples of carcinomas as well as in epithelial tumor cell lines. In thyroid carcinomas of a specific histiotype the amount of Met protein, almost undetectable in the normal counterpart, was found to be increased more than 100-fold. The tissue distribution of the Met/HGF receptor indicates that this molecule is involved in growth control of epithelial cells other than hepatocytes and suggests that its increased expression may confer a growth advantage to neoplastic cells.

c-met is amplified but not mutated in a cell line with an activated met tyrosine kinase

The putative tyrosine kinase receptor encoded by the oncogene c-met is activated (tyrosine-phosphorylated in vivo) in the human gastric carcinoma cell line GTL-16. The corresponding gene is amplified and over-expressed. In this study we show that c-met is part of an amplification unit measuring more than 3000 kb. The multiple copies of the amplicon are located on a novel chromosome different from chromosome 7. We have previously shown that the c-met protein present in GTL-16 cells is indistinguishable from that found in other cells. Kinase activation could be due to over-expression of the normal c-met protein or to the presence of activating mutation(s). To verify the primary structure of the c-met protein in GTL-16 cells we sequenced a series of overlapping cDNAs obtained from GTL-16 cell RNA by reverse transcription and polymerase chain reaction. Two differences were found in the c-met coding region with respect to the published human c-met cDNA: (1) the lack of 54 nucleotides corresponding to a stretch of 18 amino acids located in the extracellular domain of the receptor, and (2) the substitution of the codon specifying alanine 1209 (located in the tyrosine kinase domain) with one coding for glycine. However, we also obtained cDNAs identical to that just described from a number of control cell lines. These results suggest: (1) that the present c-met cDNA presumably reflects the sequence of the most abundant transcript in several cell types, and (2) that over-expression of the normal c-met protein, alone or in combination with an autocrine loop, is most probably responsible for the activation of the c-met kinase in GTL-16 cells.

Keratin 8 of simple epithelia is expressed in glia of the goldfish nervous system

The intermediate filament protein composition in glial cells of goldfish optic nerve differs from that found in glial cells of the goldfish spinal cord and brain. Brain and spinal cord glial cells contain glial fibrillary acidic protein (GFAP), whereas glial cells in the optic nerve contain ON3. The ON3 protein of the goldfish optic nerve was recently identified as the goldfish equivalent to the mammalian type II keratin 8 protein. In addition to the ON3 protein, the goldfish optic nerve also contains a 48-kDa protein. Immunoblotting experiments suggest that this protein is equivalent to the mammalian type I keratin 18 protein, which typically pairs with keratin 8 to form filaments. We show that these proteins are not specific to the optic nerve. The ON3 and 48-kDa proteins of the goldfish optic nerve share common antigenic properties with the predominant keratin pair expressed in the goldfish liver. These proteins are also expressed at low levels in the goldfish brain and spinal cord. In addition RNase protection assays and Northern blots indicate that the mRNA for the ON3 protein in optic nerve is identical to the message found in other goldfish tissues. The expression of ON3 was also examined in cultured glial cells from goldfish spinal cord and optic nerve and cultured fibroblast cells. Analysis of intermediate filament protein expression in cultured glial cells taken from goldfish spinal cord demonstrated the absence of GFAP in these cells and the expression of ON3. This protein was also the predominant intermediate filament protein of cultured optic nerve glial cells and fibroblasts. The differences in the expression of intermediate filament proteins in mammals and lower vertebrates are discussed. In addition, we discuss how the expression of a simple epithelial keratin pair in glial cells of the goldfish optic nerve may be associated with this system's capacity for continuous growth and regeneration.

Protein kinase-c activation inhibits tyrosine phosphorylation of the c-met protein

The mature product of the c-met proto-oncogene is a putative tyrosine kinase receptor of 190 kd with an alpha beta heterodimeric structure. The c-met protein is phosphorylated in vivo on the beta subunit in the gastric carcinoma cell line GTL-16 (Giordano et al., 1988). Western blots with phosphotyrosine antibodies show that tyrosine phosphorylation of the beta subunit is reduced by treatment of GTL-16 cells with protein kinase C activators (tumor promoting phorbol esters such as phorbol 12-myristate 13-acetate, TPA, and beta-phorbol 12,13-dibutyrate, PdBu, or membrane permeable synthetic diacylglycerol 1-oleyl-2-acetyl-sn-glycerol, OAG). The inactive analog alpha-phorbol 12,13-didecanoate has no effect. The inhibition induced by TPA is dose dependent and maximal after 1 h. Depletion of protein kinase-C by prolonged treatment with TPA (18-48 h) increases the phosphorylation on tyrosine of the beta subunit. Phospho-amino acid analysis of the c-met protein immunoprecipitated from [32P]orthophosphate-labelled GTL-16 cells shows that protein kinase-C activation leads to an increase in serine phosphorylation and to concomitant decrease in tyrosine phosphorylation. These results suggest that, similar to the EGF and insulin receptor, the putative receptor encoded by the c-met proto-oncogene may be negatively modulated by protein kinase-C phosphorylation.

Biosynthesis of the protein encoded by the c-met proto-oncogene

The proto-oncogene c-met encodes a transmembrane protein with structural features of a growth factor receptor. We have previously shown that the c-met protein (c-Met) is a heterodimer of two disulphide linked chains of 50 kd (alpha) and 145 kd (beta). In this work we have studied the biosynthesis of the c-met product in a gastric carcinoma cell line (GTL-16) where the c-met gene is amplified and overexpressed. Following metabolic labelling of the cells in the presence of tunicamycin, anti-met antibodies immunoprecipitate a protein of 150 kd. In pulse-chase experiments carried out in the absence of tunicamycin, a 170 kd product appears first. Within the next few minutes, this precursor modifies its SDS migration, probably as a consequence of modification(s) of its intra-chain disulphide bonds. After 45 min of chase, this single polypeptide precursor is cleaved to form a 50 kd alpha subunit and a 145 kd beta subunit that are joined by disulphide bonds in an alpha beta complex with an apparent molecular weight of 190 kd. The presence of N-linked oligosaccharides in both the precursor and the mature protein was shown by enzymatic de-glycosylation of the immunoprecipitated proteins. The half-life of the mature protein was calculated to be approximately 5h. The c-met protein has similar structure and biosynthesis in other human cell lines.

Tyrosine kinase receptor indistinguishable from the c-met protein

Growth factor receptors with protein tyrosine kinase activity are central to the control of proliferation of both normal and malignant cells. Using anti-phosphotyrosine antibodies, we have previously identified a transmembrane glycoprotein with abnormally high protein tyrosine kinase activity in a human gastric tumour cell line (GTL-16). Electrophoresis under non-reducing conditions revealed that this kinase (relative molecular mass 145,000 (145 K)) is disulphide-linked to a 50K chain in an alpha beta-complex of 190K (p190). From its novel two-chain structure, we deduced that p190 was the prototype of a new class of tyrosine kinase receptors. We now show that p190 is indistinguishable from the protein encoded by the c-met proto-oncogene and that the alpha beta-subunit structure is conserved in other human cell lines. We also show that the high level of p190 found in the GTL-16 cell line is accompanied by amplification and overexpression of c-met. This provides the first example of a functional alteration of c-met in a human tumour cell line.

A type II keratin is expressed in glial cells of the goldfish visual pathway

The predominant intermediate filament proteins of the goldfish visual pathway consist of neuronal and non-neuronal isoelectric variants (58 kd). We have isolated a cDNA clone for the glial intermediate filament protein (ON3) from an optic nerve expression library. The predicted amino acid sequence of this clone reveals that it codes for a type II keratin representing the goldfish equivalent of mammalian keratin K8. K8 has been shown to be associated with embryogenesis and development. Unlike the mammalian visual system, the goldfish visual pathway displays a remarkable capacity for functional regeneration. The expression of K8, a protein not usually expressed in glial cells but shown to be associated with development, in the goldfish optic nerve may be involved with the processes of growth and regeneration in the goldfish visual pathway.