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Mario Falchi

Publications and source records attributed to Mario Falchi.

16 recordsLinked to original sources
PubMed2026

Longitudinal dynamics of gene expression and metabolomics in an aging population cohort.

Multiomic profiling provides a comprehensive physiological overview at the molecular level, but understanding of its spatiotemporal dynamics remains limited in human populations. We profiled longitudinal whole-blood gene expression and metabolite levels in 335 females over 8 years. Levels of 5061 genes and 181 metabolites changed over time, with individual trajectories often diverging from population-level trends. Longitudinally variable genes showed cell type specificity and enrichment for aging-relevant pathways, including cardiometabolic and neurodegenerative disorders. Longitudinal trajectories were further shaped by genetics, circadian rhythm, seasonality, and environmental pollutant exposures. Integrative analyses revealed extensive static and time-variable cross-omic connectivity. Longitudinal profiling offers insight into the temporal evolution of age-related conditions at the molecular level, and understanding individual variation within these longitudinal patterns will be essential for future precision medicine approaches.

Female↗
PubMed2006

Genome-wide search for nevus density shows linkage to two melanoma loci on chromosome 9 and identifies a new QTL on 5q31 in an adult twin cohort.

The density of acquired melanocytic nevi represents an important risk factor for malignant melanoma. Total body nevus counts were collected in a cross-sectional study of 1730 healthy females from the UK Adult twin registry comprising 709 dizygous and 156 monozygous pairs. Nevus density (ND) increased up to the age of 35 years and then gradually declined. Quantitative genetic analysis showed a smaller genetic influence (36%) on ND up to 35 years, compared with after 35 years where it rose to 59%. Using a sub-sample of 1238 genotyped individuals, we performed distinct genome-wide scans for individuals above and below 35 separately. In the younger sub-sample, we confirmed a quantitative trait locus (QTL) for ND on chromosomes 9p21 (LOD=2.54), a region already linked to both familial melanoma and ND. We also observed a linkage signal on 9q21 (LOD=2.55) overlapping a recently reported susceptibility locus for ocular and cutaneous melanoma in Danish families. The strongest evidence of linkage identified a novel QTL on chromosome 5q31-32 (LOD=3.47). None of these linkages was observed in the group aged 35 years and over, which showed suggestive linkage on chromosome 2p24 (LOD=2.75). To the best of our knowledge, this is the first genome-wide search for ND in a large sample of healthy adults. The results suggest that different sets of genes are likely to influence the processes leading to the appearance of nevi and their involution. They provide both novel and replicated QTLs for nevus development, some of which might overlap with those for melanoma and warrant detailed investigation.

Adult↗
PubMed2006

Intrauterine, environmental, and genetic influences in the relationship between birth weight and lipids in a female twin cohort.

OBJECTIVE: To investigate the association between birth weight and lipid levels in a cohort of UK female twins. METHODS AND RESULTS: Birth weights and fasting blood lipid levels were available for 2900 women aged 18 to 80 years. Individual level regressions indicated that a 1-kg increase in birth weight was associated with a 0.08-mmol/L decrease in total cholesterol (95% confidence interval [CI], -0.12, -0.04) and a 0.06-mmol/L decrease in low-density lipoprotein (-0.10, -0.03). Using a regression model that includes both mean twin pair birth weight and individual twin's difference from the pair mean, we found that these significant relationships were between twin pairs only and not within pairs. We found no significant relationships for high-density lipoprotein. When monozygotic and dizygotic twins were analyzed separately we found similar effect sizes. Restricting the analysis to postmenopausal women we found stronger relationships between birth weight and lipid levels, which was attenuated after adjustment for body mass index (BMI). CONCLUSIONS: These novel results suggest that significant relationships between birth weight and lipids are mediated through shared influences on the maternal environment and do not support the hypothesis that fetal malnutrition is an important determinant of adult lipid levels. Adjustment for BMI also indicates that postnatal growth may be more important than prenatal growth.

Adult↗
PubMed2006

HIV-1 Tat regulates endothelial cell cycle progression via activation of the Ras/ERK MAPK signaling pathway.

Tat, the transactivator of HIV-1 gene expression, is released by acutely HIV-1-infected T-cells and promotes adhesion, migration, and growth of inflammatory cytokine-activated endothelial and Kaposi's sarcoma cells. It has been previously demonstrated that these effects of Tat are due to its ability to bind through its arginine-glycine-aspartic (RGD) region to the alpha5beta1 and alphavbeta3 integrins. However, the signaling pathways linking Tat to the regulation of cellular functions are incompletely understood. Here, we report that Tat ligation on human endothelial cells results in the activation of the small GTPases Ras and Rac and the mitogen-activated protein kinase ERK, specifically through its RGD region. In addition, we demonstrated that Tat activation of Ras, but not of Rac, induces ERK phosphorylation. We also found that the receptor proximal events accompanying Tat-induced Ras activation are mediated by tyrosine phosphorylation of Shc and recruitment of Grb2. Moreover, Tat enabled endothelial cells to progress through the G1 phase in response to bFGF, and the process is linked to ERK activation. Taken together, these data provide novel evidence about the ability of Tat to activate the Ras-ERK cascade which may be relevant for endothelial cell proliferation and for Kaposi's sarcoma progression.

Adaptor Proteins, Signal Transducing↗
PubMed2006

Mapping genetic loci that determine leukocyte telomere length in a large sample of unselected female sibling pairs.

Telomeres play a central role in cellular senescence and cancer pathobiology and are associated with age-related diseases such as atherosclerosis and dementia. Telomere length varies between individuals of the same age, is influenced by DNA-damaging factors such as oxidative stress, and is heritable. We performed a quantitative-trait linkage analysis using an approximate 10-cM genomewide map for mean leukocyte terminal-restriction fragment (TRF) lengths measured by Southern blotting, in 2,050 unselected women aged 18-80 years, comprising 1,025 complete dizygotic twin pairs. Heritability of mean batch-adjusted TRF was 36% (95% confidence interval [CI] 18%-48%), with a large common environmental effect of 49% (95% CI 40%-58%). Significant linkage was observed on chromosome 14 (LOD 3.9) at 14q23.2, and suggestive linkage at 10q26.13 (LOD 2.4) and 3p26.1 (LOD 2.7). This is the first report of loci, mapped in a sample of healthy individuals, that influence mean telomere variation in humans.

Chromosome Mapping↗
PubMed2006

Attenuation of ischemia/reperfusion injury in rats by the anti-inflammatory action of resveratrol.

Resveratrol (trans-3,4',5-trihydroxystilbene, CAS 501-36-0), a natural antioxidant and polyphenol found in grapes and wine, has been found to pharmacologically precondition the heart in nitric oxide (NO)-dependent manner. In the vascular system, NO functions as an endogenous inhibitor of leukocyte chemotaxis, adherence, and activation. The present study was designed to determine if resveratrol, through NO, can block the proadhesive molecules generated in the ischemic reperfused myocardium. Isolated hearts were prepared from properly anesthetized rats, and mounted on a Langendorff apparatus. The hearts were randomly assigned to one of the three groups: (i) control, (ii) resveratrol, and (iii) resveratrol + NG-nitro-L-arginine ethyl ester (L-NAME). The hearts were perfused in the absence (n = 6) or presence of 10 micromol/L resveratrol (n=6) or resveratrol + L-NAME (n = 6) for 15 min. All the hearts were then subjected to 30 min ischemia followed by 2 h of reperfusion. Ventricular function was monitored, infarct size and apoptotic cell death measured, and the proadhesive molecules and malonaldehyde formation determined in the perfusate. Resveratrol significantly improved postischemic ventricular function and reduced myocardial infarct size compared to the non-treated control group. The amount of proadhesive molecules including soluble intracellular adhesion molecule-1 (sICAM-1), endothelial leukocyte adhesion molecule-1 (sE-Selectin) and vascular cell adhesion molecule-1 (sVCAM-1) were each significantly decreased during reperfusion in the resveratrol group. L-NAME, a NO blocker, completely abolished such beneficial effects of resveratrol. The results support an anti-inflammatory action of resveratrol through a NO-dependent mechanism.

Animals↗
PubMed2005

Genome-wide scan for prospective memory suggests linkage to chromosome 12q22.

Prospective memory slips (forgetting to do something) are as part of everyday memory failure as retrospective complaints (forgetting a past event). The extent to which genes influence prospective and retrospective memory is so far unclear. This study aims to quantify the relative genetic and environmental influences on such memory slips and seeks to identify QTL's with the first genome-wide scan for such traits. A classic twin design was implemented: comprising 896 monozygotic (MZ) and 1008 dizygotic (DZ) female twin pairs aged between 19 and 85 (mean age, 51) participated. The prospective and retrospective memory questionnaire (PRMQ) consists of 16 items, eight asking about prospective memory failures and eight concerning retrospective failures. Heritability for prospective memory and retrospective memory were found to be 44% and 41%, respectively. A genome- wide scan of 489 female DZ twin pairs suggested a QTL on chromosome 12q22 for prospective memory (LOD 2.76, empirical p-value 0.0006). Within this QTL lies an obvious candidate-the SCAD gene. These results suggest that large-scale gene discovery studies are possible with self-report memory questionnaires.

Adult↗
PubMed2005

Identification of QTLs for serum lipid levels in a female sib-pair cohort: a novel application to improve the power of two-locus linkage analysis.

Using a novel approach for a two-locus model that provides a greatly increased power to detect multiple quantitative trait loci (QTLs) in simulated data, we identified in a sample of 961 female sib-pairs, three genome-wide significant QTLs for apolipoprotein A1 on chromosomes 8p21.1-q13.1 (LOD score 3.71), 9q21.32-33.1 (LOD score 3.28) and 10p15.1-p13 (LOD score 5.51), two for lipoprotein (a) on chromosomes 6q25.2-q27 (LOD score 10.18) and 21q21.1-q21.3 (LOD score 4.57) and two for triglycerides on chromosomes 4q28.3-32.1 (LOD score 3.71) and 5q23.1-q32 (LOD score 3.60). The two-locus ordered-subset analysis has led to the confirmation of known and likely identification of novel regions linked to serum lipid levels that would have otherwise been missed and deserves wider application in linkage analyses of quantitative traits. Given the relative lack of power for the sample sizes commonly used in human genetics linkage studies, minor QTL effects often go undetected and those that are detected will be upwardly biased. We show through simulation that the discrepancy between the real and estimated QTL-effects is often likely to generate an unpredictable source of false-negative errors, using multi-locus models, reducing the power to detect multiple QTLs through oligogenic linkage analysis. The successful simultaneous modelling of the identified QTLs in a multi-locus context helps to eliminate false positives and increases the power to detect linkages, adding compelling evidence that they are likely to be reliable QTLs for these lipid traits.

Chromosome Mapping↗
PubMed2005

Statistical tools for linkage analysis and genetic association studies.

Genetic mapping by linkage analysis has been an invaluable tool in the positional strategy to identify the molecular basis of many rare Mendelian disorders. With the attention of the scientific and medical community shifting towards the analysis of more common, complex traits, it has become necessary to develop new approaches that take into account the complexity of the genetic basis of these disorders and their possible interaction with other, nongenetic factors. Linkage disequilibrium studies are now becoming increasingly popular thanks to the advent of genotyping platforms that allow genome-wide searching for association between hundreds of thousands of random polymorphisms and disease phenotypes in large samples of unrelated individuals. Moreover, the definition of the disease phenotype itself is being reconsidered to include quantitative traits that may better define the underlying biologic mechanisms for many pathologic conditions. This article will review classic and new approaches to genetic mapping by linkage and association analysis and discuss the directions this field is likely to take in the near future.

Alleles↗
PubMed2004

A genomewide search using an original pairwise sampling approach for large genealogies identifies a new locus for total and low-density lipoprotein cholesterol in two genetically differentiated isolates of Sardinia.

A powerful approach to mapping the genes for complex traits is to study isolated founder populations, in which genetic heterogeneity and environmental noise are likely to be reduced and in which extended genealogical data are often available. Using graph theory, we applied an approach that involved sampling from the large number of pairwise relationships present in an extended genealogy to reconstruct sets of subpedigrees that maximize the useful information for linkage mapping while minimizing calculation burden. We investigated, through simulation, the properties of the different sets in terms of bias in identity-by-descent (IBD) estimation and power decrease under various genetic models. We applied this approach to a small isolated population from Sardinia, the village of Talana, consisting of a unique large and complex pedigree, and performed a genomewide search through variance-components linkage analysis for serum lipid levels. We identified a region of significant linkage on chromosome 2 for total serum cholesterol and low-density lipoprotein (LDL) cholesterol. Through higher-density mapping, we obtained an increased linkage for both traits on 2q21.2-q24.1, with a LOD score of 4.3 for total serum cholesterol and of 3.9 for LDL cholesterol. A replication study was performed in an independent and larger set from a genetically differentiated isolated population of the same region of Sardinia, the village of Perdasdefogu. We obtained consistent linkage to the region for total serum cholesterol (LOD score 1.4) and LDL cholesterol (LOD score 2.2), with a level of concordance uncommon for complex traits, and refined the location of the quantitative-trait locus. Interestingly, the 2q21.1-22 region has also been linked to premature coronary heart disease in Finns, and, in the adjacent 2q14 region, significant linkage with triglycerides has been reported in Hutterites.

Cholesterol↗
PubMed2003

Identification of a novel gene and a common variant associated with uric acid nephrolithiasis in a Sardinian genetic isolate.

Uric acid nephrolithiasis (UAN) is a common disease with an established genetic component that presents a complex mode of inheritance. While studying an ancient founder population in Talana, a village in Sardinia, we recently identified a susceptibility locus of approximately 2.5 cM for UAN on 10q21-q22 in a relatively small sample that was carefully selected through genealogical information. To refine the critical region and to identify the susceptibility gene, we extended our analysis to severely affected subjects from the same village. We confirm the involvement of this region in UAN through identical-by-descent sharing and autozygosity mapping, and we refine the critical region to an interval of approximately 67 kb associated with UAN by linkage-disequilibrium mapping. After inspecting the genomic sequences available in public databases, we determined that a novel gene overlaps this interval. This gene is divided into 15 exons, spanning a region of approximately 300 kb and generating at least four different proteins (407, 333, 462, and 216 amino acids). Interestingly, the last isoform was completely included in the 67-kb associated interval. Computer-assisted analysis of this isoform revealed at least one membrane-spanning domain and several N- and O-glycosylation consensus sites at N-termini, suggesting that it could be an integral membrane protein. Mutational analysis shows that a coding nucleotide variant (Ala62Thr), causing a missense in exon 12, is in strong association with UAN (P=.0051). Moreover, Ala62Thr modifies predicted protein secondary structure, suggesting that it may have a role in UAN etiology. The present study underscores the value of our small, genealogically well-characterized, isolated population as a model for the identification of susceptibility genes underlying complex diseases. Indeed, using a relatively small sample of affected and unaffected subjects, we identified a candidate gene for multifactorial UAN.

Amino Acid Sequence↗
PubMed2002

A new essential hypertension susceptibility locus on chromosome 2p24-p25, detected by genomewide search.

Essential hypertension (EH) is a complex disorder that results from the interaction of a number of susceptibility genes and environmental factors. We studied an isolated Sardinian village (Talana) in which the prevalence of hypertension is comparable to that in most Western populations. Talana exhibits features, such as slow demographic growth, high inbreeding, a low number of founders, stable lifestyle and culture, and accurate genealogical records, that make it suitable for the study of complex disorders. Clinical assessment of the entire adult population (N= approximately 1,000) identified approximately 100 hypertensive subjects. For our study, we selected the individuals with the most-severe EH (i.e., diastolic blood pressure >100 mm Hg), belonging to a single deep-rooted pedigree (12 generations), whose common ancestors lived in the 17th century. We performed a three-stage genomewide search using 36 affected individuals, by means of parametric linkage and allele-sharing approaches. LOD scores >1 were observed on chromosomes 1, 2, 13, 15, 17, and 19 (stage I). The most striking result was found in a 7.57-cM region on chromosome 2p24-p25. All five nonparametric linkage statistics estimated by the SimWalk2 program lie above the significance threshold of P<.008 for the whole region. Similar significance was obtained for 2p24-25 when parametric linkage (LOD score 1.99) and linkage disequilibrium mapping (P=.00006) were used, suggesting that a hypertension-susceptibility locus is located between D2S2278 and D2S168. This finding is strengthened by a recent report of linkage with marker D2S168 in a hypertensive sib-pair sample from China.

Chromosome Mapping↗
PubMed2002

Not all isolates are equal: linkage disequilibrium analysis on Xq13.3 reveals different patterns in Sardinian sub-populations.

Recent studies indicate that, whereas the Sardinian population as a whole is comparable to outbred populations for linkage disequilibrium (LD) mapping of common variants, LD in Sardinian sub-isolates is more extended, making these populations particularly suitable for this approach. To evaluate the extent of LD between microsatellite markers, we compared different sub-populations within Sardinia selected on the basis of their geographical position and isolation: two small isolated villages (Talana, Urzulei), two larger but remote areas (Ogliastra, Nuoro province) and a cohort of samples representing the wider Sardinian population. LD analysis was carried out by using six microsatellite markers that are located on Xq13.3 and that have been extensively studied in different populations. We found different extents and patterns of LD in the sub-population samples depending on their degree of isolation and demographic history. All LD measurements and haplotype analyses indicate that there is a decreasing trend from Talana (the most inbred population, LD up to 9.5-11.5 Mb) to the more outbred Sardinian population (LD only for intervals <2 Mb). In one village (Talana), five haplotype classes accounting for 80% of the entire sample perfectly matched five Ogliastra clusters, supporting the origin of the village from the Ogliastra genetic pool. In contrast, the other village (Urzulei) showed a different pattern of haplotypes with a closer relationship to the Nuoro region sub-population. LD analyses therefore show that even neighbouring isolate villages may differ in their genetic background. Here, we highlight the importance of selecting appropriate populations and/or sub-populations for the analysis of complex traits. Isolated sub-populations showing different extents of LD can provide a powerful method for mapping complex traits by LD scanning at relatively low marker density.

Chromosome Mapping↗
PubMed2002

Blockade of striatal adenosine A2A receptor reduces, through a presynaptic mechanism, quinolinic acid-induced excitotoxicity: possible relevance to neuroprotective interventions in neurodegenerative diseases of the striatum.

The aim of the present study was to evaluate whether, and by means of which mechanisms, the adenosine A2A receptor antagonist SCH 58261 [5-amino-7-(2-phenylethyl)-2-(2-furyl)-pyrazolo[4,3-e]-1,2,4-triazolo[1,5-c]pyrimidine] exerted neuroprotective effects in a rat model of Huntington's disease. In a first set of experiments, SCH 58261 (0.01 and 1 mg/kg) was administered intraperitoneally to Wistar rats 20 min before the bilateral striatal injection of quinolinic acid (QA) (300 nmol/1 microl). SCH 58261 (0.01 but not 1 mg/kg, i.p.) did reduce significantly the effects of QA on motor activity, electroencephalographic changes, and striatal gliosis. Because QA acts by both increasing glutamate outflow and directly stimulating NMDA receptors, a second set of experiments was performed to evaluate whether SCH 58261 acted by preventing the presynaptic and/or the postsynaptic effects of QA. In microdialysis experiments in naive rats, striatal perfusion with QA (5 mm) enhanced glutamate levels by approximately 500%. Such an effect of QA was completely antagonized by pretreatment with SCH 58261 (0.01 but not 1 mg/kg, i.p.). In primary striatal cultures, bath application of QA (900 microm) significantly increased intracellular calcium levels, an effect prevented by the NMDA receptor antagonist MK-801 [(+)-5-methyl-10,11-dihydro-5H-dibenzo [a,d] cyclohepten-5,10-imine maleate]. In this model, bath application of SCH 58261 (15-200 nm) tended to potentiate QA-induced calcium increase. We conclude the following: (1) the adenosine A2A receptor antagonist SCH 58261 has neuroprotective effects, although only at low doses, in an excitotoxic rat model of HD, and (2) the inhibition of QA-evoked glutamate outflow seems to be the major mechanism underlying the neuroprotective effects of SCH 58261.

Animals↗
PubMed2002

HIV protease inhibitors are potent anti-angiogenic molecules and promote regression of Kaposi sarcoma.

Treatment with HIV-1 protease inhibitors (PI) is associated with a reduced incidence or regression of Kaposi sarcoma (KS). Here we show that systemic administration of the PIs indinavir or saquinavir to nude mice blocks the development and induces regression of angioproliferative KS-like lesions promoted by primary human KS cells, basic fibroblast growth factor (bFGF), or bFGF and vascular endothelial growth factor (VEGF) combined. These PIs also block bFGF or VEGF-induced angiogenesis in the chorioallantoic membrane assay with a potency similar to paclitaxel (Taxol). These effects are mediated by the inhibition of endothelial- and KS-cell invasion and of matrix metalloproteinase-2 proteolytic activation by PIs at concentrations present in plasma of treated individuals. As PIs also inhibit the in vivo growth and invasion of an angiogenic tumor-cell line, these data indicate that PIs are potent anti-angiogenic and anti-tumor molecules that might be used in treating non-HIV KS and in other HIV-associated tumors.

Angiogenesis Inhibitors↗