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M Valli

Publications and source records attributed to M Valli.

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

Differential expression of beta1,3galactosyltransferases in human colon cells derived from adenocarcinomas or normal mucosa.

Two beta1,3galactosyltransferases are detected in human colon cells: one corresponds to beta3GalT1, the other (beta3GalTx) is found to be different from any cloned beta3GalT since in vitro it utilizes GlcNAc very efficiently under specific reaction conditions. Expression of beta3GalT1 transcript is high in normal colon mucosa and control neuroectodermal cells, which do not express sialyl-Lewis a antigen, and low in colon adenocarcinoma cells, as assessed by competitive RT-PCR. beta3GalTx activity is high in adenocarcinoma cells expressing sialyl-Lewis a and undetectable in all other cells, suggesting differential involvement and opposite regulation of such enzymes during carcinogenesis.

Adenocarcinoma↗
PubMed1999

Evidence for an increase in functional platelet 5-HT2A receptors in depressed patients using the new ligand [125I]-DOI.

Abnormalities in the serotonergic system have been implicated in the pathophysiology of depressive disorders. Human platelets possess serotonin-2A (5-HT(2A)) receptors, and previous research using LSD or ketanserin as ligands have indicated that their number is increased in depressed patients. Compared to other ligands previously used in platelet studies, DOI is highly selective for the 5-HT(2A) receptor and binds to its high-affinity state, therefore labeling only the receptors that are biologically coupled to the G-protein. We determined the density (Bmax) and the affinity (Kd) of 5-HT(2A) receptors labeled by [(125)I]-DOI in platelets from 21 untreated patients with major depression and 21 healthy volunteers. The density of the 5-HT(2A) binding sites was found to be increased in platelets from female depressed patients as compared to controls. No changes were observed in the Kd. We did not find any relationship between the binding parameters and either the severity of the depressive episode or the suicidal tendencies of the patients. Our results show that the number of coupled platelet 5-HT(2A) receptors is increased in depressed patients, indicating that platelet 5-HT(2A) receptor function is enhanced in depression.

Adult↗
PubMed1999

Mouse C127 cells transfected with fucosyltransferase fuc-TIII express masked Lewisx but not Lewisx antigen.

To study human alpha1,3/1,4fucosyltransferase (Fuc-TIII) as an alpha1,3 fucosyltransferase, we constructed two cell clones, C127-FT and C127-T-FT, by transfecting cDNA in parental (C127) or Polyoma T antigen expressing (C127-T) mouse cells, respectively. Both C127-FT and C127-T-FT clones express high levels of a fucosyltransferase activity kinetically similar to Fuc-TIII and an RNA that is amplified by a Fuc-TIII-specific oligonucleotide primer pair after reverse transcription. Clone C127-FT is Lewisxpositive, by flow cytometry, only after alpha-galactosidase or sialidase treatment, and releases [3H]Fuc N-glycans which efficiently bind to immobilized Griffonia simplicifolia I and Sambucus nigra lectins. Immunoblotting confirms that C127-FT glycoproteins acquire Lewisxreactivity only after specific deglycosylation, and shows that a small subset of Griffonia simplicifolia I isolectin B4reactive glycoproteins bears masked Lewisx, suggesting fine substrate recognition by Fuc-TIII. Moreover, transient transfection of H type alpha1, 2fucosyltransferase in clone C127-T-FT directs synthesis of Lewisyantigen, as detected by flow cytometry. Results indicate that Fuc-TIII expressed in C127 cells synthesizes masked Lewisxantigen while Lewisxantigen is not detectable.

Animals↗
PubMed1999

Metabolic and hemodynamic changes during recovery and tracheal extubation in neurosurgical patients: immediate versus delayed recovery.

UNLABELLED: Delayed recovery has been advocated to limit the postoperative stress linked to awakening from anesthesia, but data on this subject are lacking. In this study, we measured oxygen consumption (V(O2)) and plasma catecholamine concentrations as markers of postoperative stress. We tested the hypothesis that delayed recovery and extubation would attenuate metabolic changes after intracranial surgery. Thirty patients were included in a prospective, open study and were randomized into two groups. In Group I, the patients were tracheally extubated as soon as possible after surgery. In Group II, the patients were sedated with propofol for 2 h after surgery. V(O2), catecholamine concentration, mean arterial pressure (MAP), and heart rate (HR) were measured during anesthesia, at extubation, and 30 min after extubation. V(O2) and noradrenaline on extubation and mean V(O2) during recovery were significantly higher in Group II than in Group I (V(O2) for Group I: preextubation 215 +/- 46 mL/min, recovery 198 +/- 38 mL/min; for Group II: preextubation 320 +/- 75 mL/min, recovery 268 +/- 49 mL/min; noradrenaline on extubation for Group I: 207 +/- 76 pg/mL, for Group II: 374 +/- 236 pg/ mL). Extubation induced a significant increase in MAP. MAP, HR, and adrenaline values were not statistically different between groups. In conclusion, delayed recovery after neurosurgery cannot be recommended as a mechanism of limiting the metabolic and hemodynamic consequences from emergence from general anesthesia. IMPLICATIONS: In this study, we tested the hypothesis that delayed recovery after neurosurgery would attenuate the consequences of recovery from general anesthesia. As markers of stress, oxygen consumption and noradrenaline blood levels were higher after delayed versus early recovery. Thus, delayed recovery cannot be recommended as a mechanism of limiting the metabolic and hemodynamic consequences from emergence after neurosurgery.

Aged↗
PubMed1999

Evaluation of biological stress markers in police officers.

This study was performed on 18 police officers, in order to evaluate relations between behavior and the activity of the main hormonal systems implicated in stress management. All subjects were male volunteers with more than 2 years on the job, a type A psychological profile according to Friedman and Rosenman, suffering from no mental or physical illness. The experimental setting used to study the role of different stress factors consisted of a series of tests that re-created stressful situations that the subject might encounter in his job. The study showed that during stressful states, not only did peripheral secretion of catecholamines increase, but that the ratio of epinephrine to norepinephrine was a determinant factor. Epinephrine secretion which was elevated at the beginning, decreased when the stressful situation was clarified or controlled, whereas norepinephrine secretion remained elevated as long as the subject had to remain alert. Cortisol secretion seemed to depend upon anticipation of the stressful event more than its actual happenning.

Adult↗
PubMed1998

Beta-1,3-galactosyltransferase and alpha-1,2-fucosyltransferase involved in the biosynthesis of type-1-chain carbohydrate antigens in human colon adenocarcinoma cell lines.

We studied the beta-1,3-galactosyltransferase (GalT) and alpha-1,2-fucosyltansferase (FT) involved in the biosynthesis of type-1-chain carbohydrate antigens in human colon adenocarcinoma cell lines. We detected a GalT activity able to use GlcNAc as acceptor and found that lacto-N-biose I (Galbeta1-3GlcNAc) is the only reaction product. Such beta1,3GalT is kinetically similar to a pig trachea enzyme involved in mucin synthesis. The specific activity is high in cells that react strongly with anti-Lewis a and anti-Lewis b antibodies, and undetectable in a cell line that lacks antibody reaction. Reverse-transcriptase-mediated PCR analysis followed by DNA sequencing indicated that secretor-type alpha1,2FT is expressed in the cells, while the H type alpha1,2FT is not. The apparent Km values for donor and acceptor substrates determined for alpha1,2FT are similar to those of secretor-type alpha1,2FT and the specific activity measured correlates with Lewis b antigen expression on the cell surface. Moreover, some of the cell lines express Lewis y and H type 2 antigens, indicating that secretor type alpha1,2FT is responsible for their synthesis. Results suggest that biosynthesis of type-1-chain tumor-associated antigens in human colon carcinoma cells is operated by secretor-type alpha1,2FT, as reported in normal mucosa, and that beta1,3GalT activity may play a relevant role in its control.

Acetylglucosamine↗
PubMed1998

Human cells unable to express decoron produced disorganized extracellular matrix lacking "shape modules" (interfibrillar proteoglycan bridges).

The shapes of extracellular matrices are determined by positioning collagen fibrils in the right places, oriented and maintained viv-à-vis each other. The fibrils are linked orthogonally by dermatan/chondroitin sulfates or keratan sulfate (in small proteoglycans) attached every approximately 65 nm via their protein moieties to collagen fibrils at specific binding sites. These regular repeating structures are the "shape modules." The characteristic arrays of orthogonal interfibrillar bridges were missing and the extracellular matrix was totally disorganized in matrices produced by fibroblasts taken postmortem from skin of an electively aborted fetus which did not express decoron in culture, thus supporting the shape module hypothesis. Biglycon, dermatan sulfate, heparan sulfate, collagen, and hyaluronan were produced by these cells but did not contribute to a normal extracellular matrix. A similar electron histochemical and biochemical survey of extracellular matrices produced by seven normal and eight osteogenesis imperfecta cell lines from donors of different ages and both sexes showed no comparable disruptions of their matrices. This investigation appears to be the first to demonstrate systematically proteoglycan:collagen interactions in matrices produced by cultured human cells.

Adult↗
PubMed1998

Study of factors affecting the determination of total plasma 7-fluorobenzo-2-oxa-1,3-diazole-4-sulfonate (SBD)-thiol derivatives by liquid chromatography.

A detailed investigation of the factors affecting the determination of total plasma 7-fluorobenzo-2-oxa-1,3-diazole-4-sulfonate (SBD)-thiol derivatives (i.e. cysteine, homocysteine and cysteinylglycine) is described. Essentially, this assay entails extracting specific thiols by plasma disulphide bond reduction, protein precipitation, sulphydryl compound derivatization with the thiol-specific fluorogenic reagent ammonium 7-fluorobenzo-2-oxa-1,3-diazole-4-sulphonate (SBD-F), and subsequent separation with isocratic reversed-phase high-performance liquid chromatography. By improving the reliability of several analytical parameters (composition of the mobile phase, pretreatment of the sample using different reducing and protein precipitation agents, and optimization of the derivatization of thiols with SBD-F), a number of critical issues can be identified and solved.

Adult↗
PubMed1998

Variable penetrance of familial pheochromocytoma associated with the von Hipple Lindau gene mutation, S68W. Mutations in brief no. 150. Online.

Van Hippel-Lindau disease (VHL) is an autosomal dominantly inherited disorder, characterised by the development of clear cell renal carcinomas, CNS hemangioblastomas, retinal angiomas, pancreatic tumors, pheochromocytomas and hepatic cysts. Recently a number of families with dominant familial pheochromocytoma as the only clinical manifestation have been reported to carry mutations in the HVL gene. We describe a family in which a novel VHL S68W mutation was segregating and carrier individuals manifested with variable penetrance of isolated pheochromocytomas. Investigation of this kindred confirmed that a mutation in the VHL gene could produce isolated pheochromocytomas as the only clinical feature and was variably penetrant.

Genes, Tumor Suppressor↗
PubMed1998

Interphysician variability in defining the planning target volume in the irradiation of prostate and seminal vesicles.

With the improvements in treatment accuracy the risk exists of over-reliance on the capability of the physician to estimate the extent of the tumour. We assessed the variability between six radiotherapists in defining the planning target volume (PTV) on CT slices for three prostate tumour cases. Percentage differences between measured volumes and mean values calculated for each case ranged from -53.64 to +60.48% (SD 36.00%). There is a considerable variation in delineating the PTV, both in the cranio-caudal direction and in the in-slice extension of the areas drawn on each slice (standard deviations ranged from 0.35 to 2.64 cm2). We also checked the uncertainty in the shape and position of the contours on each CT image. The analysis was performed on three slices of one test case. As we expected, the uncertainty seems largest for seminal vesicle slices and smallest for prostatic apex slices. These results endorse the need for uncertainty analysis of all departmental processes in order to define a detailed protocol and consequently to minimize the interphysician differences in PTV delineations.

Analysis of Variance↗
PubMed1997

Mutation producing alternative splicing of exon 26 in the COL1A2 gene causes type IV osteogenesis imperfecta with intrafamilial clinical variability.

We have characterized a familial form of osteogenesis imperfecta (OI). Following the identification by ultrasound of short limbs and multiple fractures in a fetus at 25 weeks of gestation, the family was referred with a provisional diagnosis of severe OI. We detected subtle clinical and radiological signs of OI in the father and in the paternal grandmother of the proposita, who had never received a diagnosis of OI. Linkage analysis indicated COL1A2 as the disease locus. Heteroduplex analysis of reverse transcription-polymerase chain reaction (RT-PCR) amplification products of pro alpha2(I) mRNA from an affected member and subsequent sequencing of the candidate region demonstrated the presence of normal transcripts and a minority of transcripts lacking exon 26 (54 bp) of COL1A2. Sequencing of PCR-amplified genomic DNA identified an A --> G transition in the moderately conserved +3 position of the IVS 26 donor splice site. The mutant pre-mRNA molecules were alternatively spliced, yielding both full-length and deleted transcripts that represented less than 30% of the total pro alpha2(I) mRNA. The biochemical data on type I collagen synthesized by dermal fibroblasts showed intracellular retention of the mutant protein; failure to detect the shortened alpha2(I) chains either in the medium or in the cell layer may be the consequence of their instability at physiological temperature. These observations justified the mild resulting phenotype.

Adult↗
PubMed1997

Direct monitoring of prolidase activity in cultured skin fibroblasts using capillary electrophoresis.

Capillary electrophoresis (CE) was used as an alternative to current analysis schemes for detecting prolidase activity in erythrocytes and skin fibroblast cultures because of its unique selectivity and high resolving power. Kinetic measurement of peptide bond hydrolysis was performed using porcine kidney prolidase on different substrates (Gly-Pro, Leu-Pro and Ala-Pro) and by following the disappearance of the peptide-substrate's peak. The K(m) values obtained were in agreement with those previously reported. Interestingly, in the case of Phe-Pro as the substrate, simultaneous analysis of the product and parent peptide was possible, thus showing the superiority of the capillary electrophoresis (CE) assay with respect to the standard spectrophotometric method. The application of the CE technique to the characterization of prolidase activity in control and prolidase-deficient skin cultured fibroblasts was successful. Enzyme activity was easily calculated in all controls tested and the K(m) values determined were slightly lower than those obtained with the colorimetric reaction, thus confirming our assumption that the CE assay shows higher specificity than the ninhydrin technique. Our results demonstrate the feasibility of using CE as a simple and reliable technique for determining prolidase activity.

Adolescent↗
PubMed1997

Complete resolution of imidodipeptide mixtures in urine of prolidase-deficient patients using micellar electrokinetic chromatography.

The use of capillary zone electrophoresis as an efficient method for the identification of urinary imidodipeptides of prolidase-deficient patients has already been reported. However, owing to the complexity of the components excreted, the resolution of electrophoretic patterns obtained was poor. Here we examine the use of micellar electrokinetic chromatography to enhance peak resolution in order to obtain better insight into the electropherograms of patients' urine. The usefulness of sodium dodecyl sulphate as surfactant is reported: refined electropherograms were achieved using 35 mM sodium borate, pH 8.3 containing 65 mM sodium dodecyl sulphate. Almost all peaks were baseline separated, collected and sequenced. This allowed us to define the exact imidodipeptide composition of patients' urine. The possibility of identifying and thus quantifying each single peak means that comparison of urinary imidodipeptide excretion patterns from different patients can be made and the hypothesis that peptide patterns can be correlated with differing clinical severity can be investigated.

Adolescent↗
PubMed1997

Phenotypic comparison of an osteogenesis imperfecta type IV proband with a de novo alpha2(I) Gly922 --> Ser substitution in type I collagen and an unrelated patient with an identical mutation.

We examined the type I collagen synthesized by cultured dermal fibroblasts from a patient affected with osteogenesis imperfecta (OI) type IV. Both normal and abnormal trimers were produced. The mutant collagen molecules were excessively modified intracellularly, had a melting temperature 4 degrees C lower than the control, were secreted at a reduced rate, and underwent delayed processing to mature alpha chains.Molecular investigations identified a G --> A transition in one COL1A2 allele, resulting in a Gly922 --> Ser substitution in the alpha2(I) chain. The proband's mutation was demonstrated to arise "de novo" by the absence of the mutant allele restriction enzyme pattern from parental genomic DNA.We analyzed the insoluble extracellular matrix deposited by long-term cultured fibroblasts from our patient and from a previously described unrelated individual who carries an identical substitution. In both cases, the mutant chain constituted 10-15% of the total alpha chains deposited.We also present here the first detailed comparison of phenotype between unrelated OI patients with an identical collagen mutation. These two patients are both Caucasian females, ages 8 and 9 years, each diagnosed as type IV OI by the Sillence classification. They have a similar phenotype including moderate skeletal fragility with several femur fractures, dentinogenesis imperfecta, wormian bone, and reduced height and weight. We conclude that this phenotype is related both to the location of this mutation and to the similar extent of matrix incorporation by the mutant chains. Molecular and biochemical studies of unrelated individuals with identical amino acid substitutions in type I collagen resulting in either similar or dissimilar clinical outcomes will make a significant contribution to identifying the factors involved in the modulation of the OI phenotype.

Cells, Cultured↗
PubMed1997

Effects of lorazepam on film-induced differentiated emotions in healthy volunteers.

We studied the effects of lorazepam, a benzodiazepine, on differentiated emotions in healthy volunteers. In order to induce differentiated emotions, film excerpts were selected on the basis of the type of emotion they induced (fear, anger and for affective tone neutral film). For 6 days (D1 to D6), ten healthy volunteers received lorazepam (1 mg bid) or placebo in a randomized cross-over double-blind trial. During each treatment period, emotional induction occurred on D4, D5 and D6. One film excerpt (fear, anger or neutral) was presented each morning after relaxation. Evaluation was performed before and after each emotional induction and included questionnaires (Differential Emotions Scale and physical activation visual analog scales), and neurophysiological parameters (systolic and diastolic blood pressure, heart rate and norepinephrine levels). Globally, the film excerpts induced the predicted emotions. An analysis of variance was undertaken and revealed a significant effect of lorazepam versus placebo. On the Differential Emotions Scale and during fear induction, lorazepam induced a significantly higher increase in fear, anxiety and disgust emotions than placebo, whereas no effect was observed after anger induction. Lorazepam also induced a significantly higher increase in diastolic and systolic blood pressure with no change in heart rate, and physical activation items ("tears" and "faster breathing") without no significant change in norepinephrine. In conclusion, our results are consistent with an overall increase in emotional reactivity with lorazepam (1 mg bid) as compared to placebo. The pertinence of film-induced differentiated emotions has to be confirmed for clinical pharmacological use.

Adult↗
PubMed1996

Deficient expression of the small proteoglycan decorin in a case of severe/lethal osteogenesis imperfecta.

In osteogenesis imperfecta (OI) the effects of mutations in type I collagen genes generally reflect their nature and localization. Unrelated individuals sharing identical mutations present, in general, similar clinical phenotypes. However, in some such cases the clinical phenotype differs. This variable clinical expression could be the result of abnormalities in other connective tissue proteins. Since decorin is a component of connective tissue, binds to type I collagen fibrils and plays a role in matrix assembly, we studied decorin production in skin fibroblasts from OI patients. Cultured fibroblasts from one patient with extremely severe osteogenesis imperfecta (classified as type II/III) who has an alpha 1(I)gly415ser mutation were found to secrete barely detectable amounts of decorin into culture medium. Western blotting using antibodies raised against decorin confirmed the reduction of the decorin core protein and Northern blot analysis showed decorin mRNA levels below the limit of detection. Cells from a patient, with a less severe phenotype, bearing a mutation in the same position of the triple helix (alpha 1(I)gly415) expressed decorin normally. The different clinical phenotypes could be due to the differing genetic backgrounds of the patients so it is tempting to conclude that in our most severely affected patient the absence of decorin aggravates the clinical phenotype.

Blotting, Northern↗
PubMed1996

Nuclear retention of COL1A1 messenger RNA identifies null alleles causing mild osteogenesis imperfecta.

Osteogenesis imperfecta (OI) is a heritable connective tissue disorder characterized by bone fragility. Most cases of severe OI result from mutations in the coding region of the COL1A1 or COL1A2 genes yielding an abnormal collagen alpha chain. In contrast, many patients with mild OI show evidence of a null allele due to a premature stop mutation in the mutant RNA transcript. We have previously described a null allele arising from a splice donor mutation where the transcript containing the included intron was sequestered in the nucleus. Here we demonstrate that transcripts from null alleles arising from premature stop mutations are also present in the nucleus and absent in the cytoplasm. Using reverse transcriptase-PCR and single-strand conformational polymorphism of COL1A1 mRNA from patients with mild OI, we describe three patients with distinct null producing mutations identified from the mutant transcript within the nuclear compartment. A fourth patient with a Gly--->Arg expressed point mutation exhibits the mutant transcript in both compartments. Defining the distribution of allelic variants of COL1A1 mRNA in the nuclear and cytoplasmic compartments gives further insight into cell biology of OI and provides a strategy for investigating potential causes of a null allele.

Adult↗