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Francesco Pallotti

Publications and source records attributed to Francesco Pallotti.

16 recordsLinked to original sources
PubMed2006

Frequent alterations in the expression of serine/threonine kinases in human cancers.

Protein kinases constitute a large family of regulatory enzymes involved in the homeostasis of virtually every cellular process. Subversion of protein kinases has been frequently implicated in malignant transformation. Within the family, serine/threonine kinases (STK) have received comparatively lesser attention, vis-a-vis tyrosine kinases, in terms of their involvement in human cancers. Here, we report a large-scale screening of 125 STK, selected to represent all major subgroups within the subfamily, on nine different types of tumors ( approximately 200 patients), by using in situ hybridization on tissue microarrays. Twenty-one STK displayed altered levels of transcripts in tumors, frequently with a clear tumor type-specific dimension. We identified three patterns of alterations in tumors: (a) overexpression in the absence of expression in the normal tissues (10 kinases), (b) overexpression in the presence of expression by normal tissues (8 kinases), and (c) underexpression (3 kinases). Selected members of the three classes were subjected to in-depth analysis on larger case collections and showed significant correlations between their altered expression and biological and/or clinical variables. Our findings suggest that alteration in the expression of STK is a relatively frequent occurrence in human tumors. Among the overexpressed kinases, 10 were undetectable in normal controls and are therefore ideal candidates for further validation as potential targets of molecular cancer therapy.

DNA, Complementary↗
PubMed2006

Haplogroup effects and recombination of mitochondrial DNA: novel clues from the analysis of Leber hereditary optic neuropathy pedigrees.

The mitochondrial DNA (mtDNA) of 87 index cases with Leber hereditary optic neuropathy (LHON) sequentially diagnosed in Italy, including an extremely large Brazilian family of Italian maternal ancestry, was evaluated in detail. Only seven pairs and three triplets of identical haplotypes were observed, attesting that the large majority of the LHON mutations were due to independent mutational events. Assignment of the mutational events into haplogroups confirmed that J1 and J2 play a role in LHON expression but narrowed the association to the subclades J1c and J2b, thus suggesting that two specific combinations of amino acid changes in the cytochrome b are the cause of the mtDNA background effect and that this may occur at the level of the supercomplex formed by respiratory-chain complexes I and III. The families with identical haplotypes were genealogically reinvestigated, which led to the reconnection into extended pedigrees of three pairs of families, including the Brazilian family with its Italian counterpart. The sequencing of entire mtDNA samples from the reconnected families confirmed the genealogical reconstruction but showed that the Brazilian family was heteroplasmic at two control-region positions. The survey of the two sites in 12 of the Brazilian subjects revealed triplasmy in most cases, but there was no evidence of the tetraplasmy that would be expected in the case of mtDNA recombination.

DNA, Mitochondrial↗
PubMed2006

Molecular cloning and characterization of UDP-glucose dehydrogenase from the amphibian Xenopus laevis and its involvement in hyaluronan synthesis.

UDP-glucose dehydrogenase (UGDH) supplies the cell with UDP-glucuronic acid (UDP-GlcUA), a precursor of glycosaminoglycan and proteoglycan synthesis. Here we reported the cloning and the characterization of the UGDH from the amphibian Xenopus laevis that is one of the model organisms for developmental biology. We found that X. laevis UGDH (xUGDH) maintained a very high degree of similarity with other known UGDH sequences both at the genomic and the protein levels. Also its kinetic parameters are similar to those of UGDH from other species. During X. laevis development, UDGH is always expressed but clearly increases its mRNA levels at the tail bud stage (i.e. 30 h post-fertilization). This result fits well with our previous observation that hyaluronan, a glycosaminoglycan that is synthesized using UDP-GlcUA and UDP-N-acetylglucosamine, is abundantly detected at this developmental stage. The expression of UGDH was found to be related to hyaluronan synthesis. In human smooth muscle cells the overexpression of xUGDH or endogenous abrogation of UGDH modulated hyaluronan synthesis specifically. Our findings were confirmed by in vivo experiments where the silencing of xUGDH in X. laevis embryos decreased glycosaminoglycan synthesis causing severe embryonic malformations because of a defective gastrulation process.

Animals↗
PubMed2006

Matrix metalloproteinase 2 and tissue inhibitors of metalloproteinases regulate human aortic smooth muscle cell migration during in vitro aging.

As a direct correlation between aging and the risk of onset of vascular disease has been universally accepted, we prepared an in vitro aging model consisting in sequential passages of human aortic smooth muscle cells (AoSMC) in order to evaluate the cell behavior changes during aging. Because matrix metalloproteinases (MMP) are actively involved in matrix remodeling and disease outcome, in our model we found active MMP-2 only in the conditioned medium of young AoSMCs, whereas aged cells showed only the inactive zymogen form of MMP-2 (pro-MMP-2). We ascribed the pro-MMP-2 activation in young cells to an increase in membrane type 1 matrix metalloproteinase (MT1-MMP) content. Furthermore, we found that transcripts coding for tissue inhibitor of metalloproteinases (TIMPs) were up-regulated in aged cells, and this increase of TIMPs could also prevent pro-MMP-2 activation in aged cells. Moreover, we demonstrated that young AoSMCs possess higher migratory capabilities than aged cells. The young AoSMC migration can be inhibited by adding TIMP-1 and TIMP-2 to the cells reproducing aged AoSMC migratory behavior. Finally, the role of MMP-2 and TIMP-2 in AoSMC migration was confirmed silencing MMP-2 and TIMP-2 in young and aged AoSMCs, respectively; therefore, in this study we showed that these enzymes play a pivotal role in the regulation of the AoSMC migration during in vitro aging.

Aorta↗
PubMed2006

Acute suppuration of the pancreatic duct associated with pancreatic ductal obstruction due to pancreas carcinoma.

Acute obstructive suppurative cholangitis is a well-known clinical entity; however, acute suppuration of the pancreatic duct in the setting of pancreatic ductal obstruction is an uncommon pancreatic disorder. We report a case of acute suppuration of the pancreatic duct without either a concomitant pancreatic abscess or an infected pseudocyst, presenting as acute relapsing pancreatitis. In this case, the underlying cause of suppuration of the pancreatic duct was pancreatic ductal obstruction and chronic pancreatitis secondary to pancreas head carcinoma along with infection of Escherichia coli. Endoscopic placement of a pancreatic stent resulted in an evacuation of grayish thick pus from the distal pancreatic duct with a dramatic improvement of the disease. This case proposes the concept that acute suppuration of the pancreatic duct is a complex process involving the chronically damaged pancreas, pancreatic outflow obstruction, and subsequent bacterial infection. Antibiotic treatment is effective but temporary; therefore, the immediate drainage of the infected pancreatic duct is mandatory.

Aged↗
PubMed2005

Decorin from different bovine tissues: study of glycosaminoglycan chain by PAGEFS.

The sulphation pattern of glycosaminoglycan (GAG) plays a critical role in biological functions of proteoglycans. In this study, we showed that decorins from different bovine tissues present specific sulphation pattern coupled with peculiar biological activity. In order to elucidate chemical structure of decorin glycosaminoglycan chains, we improved an electrophoretic method to analyse fluorescent disaccharides from dermatan/chondroitin sulphate GAG chains. The disaccharide separation is based on minigels, and this technique was able to define the polysaccharide chain composition in terms of sulphated and not sulphated disaccharides. This approach allowed not only the measurement of few picomoles of material, but it also permits a rapid qualitative analysis of the GAG chains. Data obtained by PAGEFS indicate that the sulphation pattern of GAG is tissue specific and this finding may explain the different binding properties to von Willebrand factor of decorins.

Animals↗
PubMed2005

Comparison of three strategies for myocardial protection during coronary artery bypass graft surgery based on markers of cardiac damage.

OBJECTIVES: To evaluate myocardial damage during coronary artery bypass grafting using three different intermittent cardioplegia and then measuring cTnI and CKMBm release. DESIGN AND METHODS: Forty-two patients belonging to the hypothermic crystalloid (n = 16), hypothermic (n = 13), and normothermic blood (n = 13) groups were collected when removing the aortic cross-clamp (t = 0) and after 4, 12, 24 and 48 h. For each patient, cumulative cTnI and CKMBm release was calculated as the five measurement mean. There were no significant preoperative and operative differences in the three groups. RESULTS: In the normothermic group, cTnI mean values at 4, 12, and 24 h were significantly lower than those in both hypothermic groups; moreover, CKMBm mean values were higher at 4, 12, and 24 h in the hypothermic crystalloid group and at 4 and 12 h in the hypothermic blood group than in the normothermic group. In the normothermic group, the area under the curve of the release of both markers was significantly lower than in the hypothermic groups. No significant difference was reported in the release of both markers in hypothermic groups. CONCLUSIONS: A strategy of normothermic cardioplegia seems to preserve myocardium better than hypothermic cardioplegia.

Aged↗
PubMed2004

Biochemical analysis of respiratory function in cybrid cell lines harbouring mitochondrial DNA mutations.

We analysed key biochemical features that reflect the balance between glycolysis and glucose oxidation in cybrids (cytoplasmic hybrids) harbouring a representative sample of mitochondrial DNA point mutations and deletions. The cybrids analysed had the same 143B cell nuclear background and were isogenic for the mitochondrial background. The 143B cell line and its rho(0) counterpart were used as controls. All cells analysed were in a dynamic state, and cell number, time of plating, culture medium, extracellular volume and time of harvest and assay were strictly controlled. Intra- and extra-cellular lactate and pyruvate levels were measured in homoplasmic wild-type and mutant cells, and correlated with rates of ATP synthesis and O2 consumption. In all mutant cell lines, except those with the T8993C mutation in the ATPase 6 gene, glycolysis was increased even under conditions of low glucose, as demonstrated by increased levels of extracellular lactate and pyruvate. Extracellular lactate levels were strictly and inversely correlated with rates of ATP synthesis and O2 consumption. These results show increased glycolysis and defective oxidative phosphorylation, irrespective of the type or site of the point mutation or deletion in the mitochondrial genome. The different biochemical consequences of the T8993C mutation suggest a uniquely different pathogenic mechanism for this mutation. However, the distinct clinical features associated with some of these mutations still remain to be elucidated.

Adenosine Triphosphate↗
PubMed2002

Pathogenesis of the deafness-associated A1555G mitochondrial DNA mutation.

The pathogenic mechanisms of the A1555G mitochondrial DNA mutation in the 12S rRNA gene, associated with maternally inherited sensorineural deafness, are largely unknown. Previous studies have suggested an involvement of nuclear factor(s). To address this issue cybrids were generated by fusing osteosarcoma cells devoid of mtDNA with enucleated fibroblasts from two genetically unrelated patients. Furthermore, to determine the contribution, if any, of the mitochondrial and nuclear genomes, separately or in combination, in the expression of the disease phenotype, transmitochondrial fibroblasts were constructed using control and patient's fibroblasts as nuclear donors and homoplasmic mutant or wild-type cybrids as mitochondrial donors. Detailed analysis of mutant and wild-type cybrids from both patients and transmitochondrial fibroblast clones did not reveal any respiratory chain dysfunction suggesting that, if nuclear factors do indeed act as modifier agents, they may be tissue-specific. However, in the presence of high concentrations of neomycin or paromomycin, but not of streptomycin, mutant cells exhibit a decrease in the growth rate, when compared to wild-type cells. The decrease did not correlate with the rate of synthesis or stability of mitochondrial DNA-encoded subunits or respiratory chain activity. Further studies are required to determine the underlying biochemical defect.

Adult↗
PubMed2002

Biochemical-clinical correlation in patients with different loads of the mitochondrial DNA T8993G mutation.

OBJECTIVE: To investigate the correlation between biochemical and clinical phenotype in 6 patients from 3 unrelated families with different mutation loads (heteroplasmy) of the T8993G mitochondrial DNA mutation associated with neuropathy, ataxia, and retinitis pigmentosa-Leigh syndrome. METHODS: We studied adenosine triphosphate (ATP) synthase activity (synthesis and hydrolysis) in platelet-derived submitochondrial particles and assessed mutant loads both in platelets used for biochemical analysis and in other available tissues. Biochemical and molecular results were correlated with clinical features. RESULTS: The rate of ATP hydrolysis was normal, but ATP synthesis was severely impaired (30% to 4% of residual activity) in patients harboring 34% to 90% mutant mitochondrial DNA, without any evidence of a threshold for the expression of this defect. There was little variation in heteroplasmy among tissues from each patient, but wider variability was detected in 2 mothers. Correlation of heteroplasmy and clinical and biochemical features suggested that ATP synthesis is defective at mutant loads as low as 34% and is extremely reduced at mutant loads above 80% when the phenotype is neuropathy, ataxia, and retinitis pigmentosa-Leigh syndrome. CONCLUSIONS: This study indicates a close relationship between tissue heteroplasmy, expression of the biochemical defect in platelets, and clinical involvement. The biochemical defect was greater than previously reported, and we found no evidence of a biochemical threshold. The uniform distribution of high mutant loads among our patients' tissues suggests a differential tissue-specific reliance on mitochondrial ATP synthesis.

Adenosine Triphosphate↗
PubMed2002

Mitochondrial DNA nucleotide changes C14482G and C14482A in the ND6 gene are pathogenic for Leber's hereditary optic neuropathy.

A novel mitochondrial DNA nucleotide transversion, C14482A (M64I), different from the previously reported C14482G (M64I), was found to cause Leber's hereditary optic neuropathy with visual recovery in an Italian family. These equivalent changes are the fifth pathogenic mutation for pure Leber's hereditary optic neuropathy. This confirms that the ND6 gene of complex I is a mutational hot spot and suggests that different amino acid substitutions at residue 64, as induced by C14482G or C14482A (M64I) and the common T14484C (M64V) mutations, are associated with visual recovery.

Adolescent↗
PubMed2002

Rescue of a mitochondrial deficiency causing Leber Hereditary Optic Neuropathy.

A G to A transition at nucleotide 11778 in the ND4 subunit gene of complex I was the first point mutation in the mitochondrial genome linked to a human disease. It causes Leber Hereditary Optic Neuropathy, a disorder with oxidative phosphorylation deficiency. To overcome this defect, we made a synthetic ND4 subunit compatible with the "universal" genetic code and imported it into mitochondria by adding a mitochondrial targeting sequence. For detection we added a FLAG tag. This gene was inserted in an adeno-associated viral vector. The ND4FLAG protein was imported into the mitochondria of cybrids harboring the G11778A mutation, where it increased their survival rate threefold, under restrictive conditions that forced the cells to rely predominantly on oxidative phosphorylation to produce ATP. Since assays of complex I activity were normal in G11778A cybrids we focused on changes in ATP synthesis using complex I substrates. The G11778A cybrids showed a 60% reduction in the rate of ATP synthesis. Relative to mock-transfected G11778A cybrids, complemented G11778A cybrids showed a threefold increase in ATP synthesis, to a level indistinguishable from that in cybrids containing normal mitochondrial DNA. Restoration of respiration by allotopic expression opens the door for gene therapy of Leber Hereditary Optic Neuropathy.

Adenosine Triphosphate↗
PubMed2002

Mitochondrial abnormalities in muscle and other aging cells: classification, causes, and effects.

The involvement of mitochondria and of mitochondrial DNA (mtDNA) in the aging process has generated much interest and even more controversy. The mitochondrial theory of aging considers a vicious circle consisting of: (1) accumulation of somatic mtDNA mutations; (2) impairment of respiratory chain function; (3) increased production of reactive oxygen species (ROS) in mitochondria; and (4) further damage to mtDNA. We review the evidence for and against the belief that these steps occur in aging muscle and brain, considering separately morphological, biochemical, and molecular data. The relationship between mitochondrial aging and late-onset neurodegenerative diseases is briefly reviewed. We conclude that mitochondrial dysfunction does play a crucial role in the aging process of both muscle and brain, but it remains unclear whether mitochondria are the culprits or mere accomplices.

Animals↗
PubMedDate not supplied

Renal ultrastructural findings in Anderson-Fabry disease.

Anderson-Fabry disease (AFd) is caused by an X-linked inborn error in the glycosphingoLipid metabolic pathway due to an enzymatic defect in a lysosomal hydrolase: alpha-galactosidase A. The defect results in the progressive accumulation of neutral glycosphingolipids in most body fluids and several tissues. The clinical manifestations of AFd are related to organ damage and, obviously, are more severe in hemizygous males than in heterozygous females. In the third decade of life, the course of the disease involves severe deterioration of kidney function progressing to end-stage renal failure. All kind of cells of renal structures are filled with glycosphingolipid deposits. Electron microscopic studies document typical intracytoplasmic osmiophilic bodies with a characteristic "zebra" or "onion-skin" appearance due to concentric lamellation of alternating clear and dark layers. Clinical interest in Fabry patients is related to recent advances in treatment with an intravenous specific enzyme to modify the biochemical error of the glycosphingolipid catabolic pathway.

Chromosomes, Human, X↗
PubMedDate not supplied

Glomerular changes in hereditary single-gene diseases.

Molecular genetics has strongly influenced clinical medicine and particularly nephrology. Several gene mutations of single-gene hereditary nephropathies have been recently identified. These data are useful to develop methods of diagnosis and treatment, but also to understand the pathogenesis of these particular disorders. In this review we focused on several monogenic hereditary renal diseases inducing nephrotic syndrome and other hereditary diseases with renal involvement and progression towards end-stage renal failure.

Genetic Diseases, Inborn↗