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Biomedical subjects

A Pizzuti

Publications and source records attributed to A Pizzuti.

At least 19 recordsLinked to original sources
PubMed2005

LGI1 gene mutation screening in sporadic partial epilepsy with auditory features.

Partial epilepsy with auditory features occasionally segregates in families as an autosomal dominant trait. In some families mutations in the leucine-rich glioma inactivated (LGI1) gene have been identified. Sporadic cases might harbour either denovo or low-penetrant LGI1 mutations, which will substantially alter the family risk for epilepsy. We selected sixteen sporadic patients with cryptogenic temporal lobe epilepsy and partial seizures with auditory features. We compared clinical features of these patients with those of published autosomal dominant family cases. We screened these patients for LGI1 mutations. Comparing the sporadic patients with the published familial cases no difference in either the primary auditory features or in the other associated epileptic manifestations was identified. Sequence analysis of the whole LGI1 gene coding regions in sporadic patients did not reveal changes in the LGI1 gene. The genetic analysis demonstrates that LGI1 is not a major gene for sporadic cases of partial epilepsy with auditory features at least in the Italian population. Screening of sporadic patients for LGI1 mutations appears not useful in genetic counselling of these patients.

Adult↗
PubMed2004

Preliminary data suggest that mutations in the CgRP pathway are not involved in human sporadic cryptorchidism.

In testicular descent to the scrotum, a multistep process, many anatomical and hormonal factors play a role. Cryptorchidism occurs in about 1-2% of males and may cause secondary degeneration of the testes. Animal models have shown that abnormalities, in the calcitonin gene-related peptide (CgRP) activity, could be relevant in the pathogenesis of cryptorchidism. We performed a mutation screening by PCR exon amplification, single-strand conformation polymorphism (SSCP) and sequencing in four candidate genes, CgRPs (alphaCgRP, betaCgRP), their receptor (CgRPR) and the receptor component protein (CgRP-RCP), in 90 selected cases of idiopathic unilateral or bilateral cryptorchidism. Mutation screening of the coding regions and intron-exon boundaries revealed some polymorphic variants but no pathogenic sequence changes. These preliminary data suggest that these genes are not major factors for cryptorchidism in humans.

Adult↗
PubMed2003

A novel PTPN11 mutation in LEOPARD syndrome.

PTPN11 gene mutations are common to both patients with Noonan (NS) and LEOPARD syndrome (LS). So far only two recurrent mutations have been identified in LS patients by different research groups, i.e., Tyr279Cys and Thr468Met. In this work we describe the third PTPN11 mutation that has been found in a single LS patient. The mutation (c.1517A>C) substitutes a proline for a glutamine at amino acid 506 (Gln506Pro) in the phosphatase domain (PTP) of the PTPN11 peptide SHP2. This region is a mutation hotspot. Changes at amino acids 501 to 504 cause NS. Gln506Pro is predicted, by modeling analysis, to seriously disrupt the normal contacts between the regulating N-SH2 and the active PTP domains, leading to hyperactivity of the phosphatase. This report demonstrates that rarer mutations other than Tyr279Cys and Thr468Met can be found in LS patients and the need of screening the whole gene in those negative for the commonest mutations.

Adult↗
PubMed2003

Dysmyelinating sensory-motor neuropathy in merosin-deficient congenital muscular dystrophy.

A 20-year-old man with mild myopathy, external ophthalmoparesis, epilepsy, and diffuse white matter hyperintensity in the brain on magnetic resonance imaging had partial merosin deficiency in muscle and absent merosin in the endoneurium. Motor and sensory nerve conduction velocities were slow. Nerve biopsy showed reduction of large myelinated fibers, short internodes, enlarged nodes, excessive variability of myelin thickness, tomacula, and uncompacted myelin, but no evidence of segmental demyelination, naked axons, or onion bulbs. Thus, in congenital muscular dystrophy, merosin expression may be dissociated in different tissues, and the neuropathy is sensory-motor and due to abnormal myelinogenesis.

Adult↗
PubMed2003

Mapping of a new autosomal dominant non-syndromic hearing loss locus (DFNA43) to chromosome 2p12.

Hearing impairment (HI) is the most frequent sensory defect with wide genetic heterogeneity. Approximately 80% of genetic hearing loss is non-syndromic and 15-25% of exhibit autosomal dominant inheritance. We analysed an Italian three generation family in which non-syndromic hearing impairment is transmitted as an autosomal dominant trait. Onset of HI in all affected subjects occurred in the second decade of life, with subsequent gradual progression from moderate to profound loss. HI was bilateral and symmetrical, involving all frequencies. After exclusion of the known DFNA loci with markers from the Hereditary Hearing Loss Homepage (URL: http://dnalab-www.uia.ac.be/dnalab/hhh), a genome wide scan was carried out using 358 highly informative microsatellite markers. Significant linkage (Zmax=4.21, theta=0) was obtained with chromosome 2p12 markers. The results were confirmed by multipoint analysis (Zmax=4.51), using the location score method. Haplotype analysis defined a 9.6 cM disease gene interval on chromosome 2 without overlap with the other identified loci. Fine mapping and identification of candidate genes are in progress.

Chromosome Mapping↗
PubMed2003

Severe infantile hyperkalaemic periodic paralysis and paramyotonia congenita: broadening the clinical spectrum associated with the T704M mutation in SCN4A.

The authors describe an Italian kindred with nine individuals affected by hyperkalaemic periodic paralysis associated with paramyotonia congenita (hyperPP/PMC). Periodic paralysis was particularly severe, with several episodes a day lasting for hours. The onset of episodes was unusually early, beginning in the first year of life and persisting into adult life. The paralytic episodes were refractory to treatment. Patients described minimal paramyotonia, mainly of the eyelids and hands. All affected family members carried the threonine to methionine substitution at codon 704 (T704M) in exon 13 of the skeletal muscle voltage gated sodium channel gene (SCN4A). The association between T704M and the hyperPP/PMC phenotype has been only recently revealed. Nevertheless, such a severe phenotype has never been reported so far in families with either hyperPP or hyperPP/PMC. These data further broaden the clinical spectrum of T704M and support the evidence that this mutation is a common cause of hyperPP/PMC.

Adolescent↗
PubMed2001

Genomic organization, physical mapping, and involvement in Yq microdeletions of the VCY2 (BPY 2) gene.

VCY2 is a gene positioned within the AZFc locus of the Y chromosome, a region frequently deleted in infertile males. To investigate the involvement of this gene in idiopathic male infertility, we studied its genomic organization and localization. Analysis of the genomic structure demonstrated that the VCY2 gene is composed of 9 exons spanning 21 kb. FISH analysis on interphase nuclei with specific probes for exons 4-6, 7, and 8 demonstrated the presence of a single gene copy, and Fiber-FISH on relaxed chromatin indicated that VCY2 is located within the DAZ gene cluster. PCR, Southern blot, and FISH analysis on infertile patients with Yq microdeletions demonstrated the absence of VCY2 in all cases where deletions involved the DAZ gene, raising the question about the role of the VCY2 gene loss in the phenotype reported for DAZ-deleted patients.

Blotting, Southern↗
PubMed2001

Seven novel point mutations in the uroporphyrinogen decarboxylase (UROD) gene in patients with familial porphyria cutanea tarda (f-PCT).

In this work, we describe seven novel molecular defects in the uroporphyrinogen decarboxylase gene responsible for familial porphyria cutanea tarda in Italian subjects with reduced erythrocyte URO-D activity. Four of these molecular abnormalities (R142Q, L161Q, S219F, P235S) are missense mutations, one (Q206X) is a nonsense mutation, one (IVS8-1 G>C) is a splicing defect causing the exon 9 deletion and one (1107 G>A) is located in the 3' untranslated region of UROD gene. All the amino acid substitutions fall in conserved regions in several organisms suggesting an important role in catalysis or in the protein structure stabilization. Three of these mutations have been detected in more than one subject. These results suggest a molecular heterogeneity at the UROD locus in Italian PCT patients although recurrent mutations have been identified.

3' Untranslated Regions↗
PubMed2001

Clinical value of left atrial appendage flow velocity for predicting of cardioversion success in patients with non-valvular atrial fibrillation.

BACKGROUND: Echocardiographic parameters for predicting cardioversion outcome in patients with non-valvular atrial fibrillation are not accurately defined. OBJECTIVE: To evaluate the role of left atrial appendage flow velocity detected by transoesophageal echocardiography for prediction of cardioversion outcome in patients with non-valvular atrial fibrillation enrolled in a prospective. multicentre, international study. METHODS: Four hundred and eight patients (257 males, mean age: 66 +/- 10 years) with non-valvular atrial fibrillation lasting more than 48 h but less than 1 year underwent transthoracic echocardiography and transoesophageal echocardiography before either electrical (n=324) or pharmacological (n=84) cardioversion. RESULTS: Cardioversion was successful in restoring sinus rhythm in 328 (80%) and unsuccessful in 80 patients (20%). Mean left atrial appendage peak emptying flow velocity was significantly higher in patients with successful than in those with unsuccessful cardioversion (32.4 +/- 17.7 vs 23.5 +/- 13.6 cm x s(-1); P<0.0001). At multivariate logistic regression analysis, three parameters proved to be independent predictors of cardioversion success: the atrial fibrillation duration <2 weeks (P=0.011, OR=4.9, CI 95%=1.9-12.7), the mean left atrial appendage flow velocity >31 cm x s(-1) (P=0.0013, OR=2.8, CI 95%=1.5-5.4) and the left atrial diameter <47 mm (P=0.093, OR=2.0, CI 95%=1.2-3.4). These independent predictors of cardioversion success outperformed other univariate predictors such as left ventricular end-diastolic diameter <58 mm, ejection fraction >56% and the absence of left atrial spontaneous echo contrast. CONCLUSION: In patients with non-valvular atrial fibrillation, measurement of the left atrial appendage flow velocity profile by transoesophageal echocardiography before cardioversion provides valuable information for prediction of cardioversion outcome.

Atrial Appendage↗
PubMed2001

Human developing motor neurons as a tool to study ALS.

Defining the basis of the selective cell vulnerability of human motor neurons (hMNs) represents a crucial step in revealing the pathogenesis of amyotrophic lateral sclerosis (ALS). Tissue culture models offer an ideal system for identification of the hMN-specific features at the single cell level. Purified hMNs and astrocytes can today be isolated from the anterior horn of the human embryonic spinal cord. Cultures can be studied at the single cell level using cDNA/mRNA amplification techniques. The effects of molecules affecting hMN survival, neurite extension, and metabolism can be tested in vitro and the expression of selective genes assayed using DNA microarray technology. Crucial information of immediate clinical application for the treatment of patients affected by ALS can be derived after testing the efficacy of candidate pharmaceutical molecules using in vitro cell models. Adult nervous tissue or progenitor cells derived from different regions of the nervous system may be used as an alternative source of human neuronal cells. HMNs in culture, combined with the application of adequate technology, can contribute greatly to identifying the primitive critical events responsible for the cell degeneration observed in ALS, bypassing the intrinsic limitations of the non-human models of the disease.

Amyotrophic Lateral Sclerosis↗
PubMed2001

Cloning and molecular characterization of three ubiquitin fusion degradation 1 (Ufd1) ortholog genes from Xenopus laevis, Gallus gallus and Drosophila melanogaster.

The yeast ubiquitin fusion degradation 1 (Ufd1) protein is involved in a degradation pathway for ubiquitin fused products. The human ortholog gene (UFD1-like, UFD1L) is deleted in patients affected by the DiGeorge/velocardiofacial syndromes. We report the cloning of UFD1L orthologs from Drosophila melanogaster (dufd1l), Xenopus laevis and Gallus gallus. The 1,125-bp Drosophila cDNA encodes a protein of 316 amino acids, showing 60% identity with the human and murine proteins. The identity to the G. gallus, X. laevis, C. elegans and S. cerevisiae proteins is 95%, 83%, 32%, and 36%, respectively. Northern expression data in Drosophila indicate that dufd1l is expressed through embryonic, larval and pupal development, as well as in the adult fly.

Adaptor Proteins, Vesicular Transport↗
PubMed2001

The Q121 PC-1 variant and obesity have additive and independent effects in causing insulin resistance.

PC-1 is a membrane glycoprotein that impairs insulin receptor function. Its K121Q polymorphism is a genetic determinant of insulin resistance. We investigated whether the PC-1 gene modulates insulin sensitivity independently of weight status (i.e. both in nonobese and obese individuals). Nondiabetic subjects [164 males, 267 females; age, 37 +/- 0.6 yr, mean +/- SEM; body mass index (BMI), 32.7 +/- 0.5 kg/m(2)], who were subdivided into 220 nonobese (BMI < or = 29.9) and 211 obese, were studied. Although subjects were nondiabetic by selection criteria, plasma insulin concentrations during oral glucose tolerance test were higher (P < 0.05) in Q allele-carrying subjects (K121Q or Q121Q genotypes), compared with K121K individuals, in both the nonobese and obese groups. Insulin sensitivity, measured by euglycemic clamp in a representative subgroup of 131 of 431 randomly selected subjects, progressively decreased (P < 0.001) from nonobese K121K [n = 61; glucose disposal (M) = 34.9 +/- 1.1 micromol/kg/min] to nonobese Q (n = 21; M = 29.9 +/- 2.0), obese K121K (n = 31, M = 18.5 +/- 1.2), and obese Q (n = 18, M = 15.5 +/- 1.2) carriers. The K121Q polymorphism was correlated with insulin sensitivity independently (P < 0.05) of BMI, gender, age, and waist circumference. In conclusion, the Q121 PC-1 variant and obesity have independent and additive effects in causing insulin resistance.

Adolescent↗
PubMed2001

The Q allele variant (GLN121) of membrane glycoprotein PC-1 interacts with the insulin receptor and inhibits insulin signaling more effectively than the common K allele variant (LYS121).

When overexpressed, the membrane glycoprotein PC-1 may play a role in human insulin resistance through the inhibition of insulin receptor (IR) autophosphorylation. A PC-1 variant (K121Q, with lysine 121 replaced by glutamine) is also associated with whole-body insulin resistance when not overexpressed. To better understand the effects of the Q allele on IR function and downstream signaling, we transfected cultured cells with cDNAs for either the Q or the K alleles. In human MCF-7 cells, the Q allele was severalfold more effective (P < 0.05-0.01) than the K allele in reducing insulin stimulation of IR autophosphorylation, insulin receptor substrate-1 phosphorylation, phosphatidylinositol 3-kinase activity, glycogen synthesis, and cell proliferation. Similar data on IR autophosphorylation inhibition were also obtained in mouse R-/hIR and human HEK 293 cell lines. In transfected MCF-7 cells, 125I-labeled insulin binding and IR content were unchanged, and PC-1 overexpression did not influence IGF-1 stimulation of IGF-1 receptor autophosphorylation. Both the Q and K alleles directly interacted with the IR, as documented by coimmunoprecipitation assays. This interaction was greater for the Q allele than for the K allele (P < 0.01), suggesting that direct PC-1-IR interactions are important for the PC-1 inhibitory effect on insulin signaling. In conclusion, the Q allele has stronger inhibitory activity on IR function and insulin action than the more common K allele, and this is likely a consequence of the intrinsic characteristics of the molecule, which more strongly interacts with the IR.

Alleles↗