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Biomedical subjects

F Bernardi

Publications and source records attributed to F Bernardi.

At least 55 records · Page 3Linked to original sources
PubMed2001

A highly polymorphic microsatellite in the factor V gene is an informative tool for the study of factor V-related disorders.

The role of factor V (FV) mutations in activated protein C (APC) resistance and FV deficiency is well established. We report on the identification of a highly polymorphic (AT)n microsatellite marker in the FV gene, which represents an informative tool for the investigation of the origin and evolution of pathologically relevant FV genetic components. A high number of different microsatellite alleles were found to be associated with FV R506Q and FV H1299R, two single-origin mutations. An example of the use of the microsatellite marker in family studies of thrombophilia and FV deficiency is also provided.

Factor V↗
PubMed2001

Role of the mechanical properties of tracheobronchial airways in determining the respiratory resistance time course.

A physiologically based simulation model of breathing mechanics was considered in an attempt to interpret and explain the time course of input respiratory resistance during the breathing cycle, observed in recent studies on ventilated patients. The model assumes a flow-dependent Rohrer resistance for the upper extrathoracic airways and volume-dependent resistance and elastance for the intermediate airways. A volume-dependent resistance describes the dissipative pressure loss in the lower airways, and two constant elastances represent lung and chest wall elasticity. Simulated mouth flow and pressure signals obtained in a variety of well-controlled conditions were used to analyze total respiratory resistance and elastance estimated by an on-line algorithm based on a time-varying parameter model. These estimates were compared with those provided by classical estimation algorithms based on time-invariant models with two, three, and four parameters. The results show that the four-parameter model is difficult to identify, while the three-parameter one offers no substantial advantage for estimating input resistance with respect to the more simple two-parameter model. In contrast, the time-varying approach provides good on-line estimates of the simulated end-expiration and end-inspiration resistances. These values provide further information of potential clinical utility, with respect to time-invariant models. For example, the results show that the difference between the end-expiration and end-inspiration resistance increases when obstructions shift from the upper to the lower airways. The similarity of the results obtained with measured and simulated data indicates that, in spite of its simplicity, the simulation model describes important physiological mechanisms underlying changes in respiratory input resistance, specifically the mechanical properties of intermediate airways.

Airway Resistance↗
PubMed2001

Functional properties of factor V and factor Va encoded by the R2-gene.

Carriership of the factor V (FV) gene marked by the R2-haplotype, a series of linked polymorphisms encoding several amino acid changes in FV, is associated with mild resistance to activated protein C (APC) and with an increased risk of thrombosis. We compared the functional properties of normal FV(a) and R2-FV(a) in model systems and in plasma. FV and R2-FV were equally well activated by thrombin and expressed identical cofactor activities in prothrombin activation. Rate constants of APC-catalyzed inactivation of FVa and R2-FVa were similar both with and without protein S. However, significant differences were observed between haemostatic parameters determined in plasma from homozygous carriers of the R2-gene (n = 5) and age-matched non-carriers (n = 19). Plasma from R2-carriers contained significantly lower FV levels and the ratio of the two FV isoforms (FV1 and FV2) was shifted in favor of FV1. The FV2/FV1 ratio was 1.4 (95% CI = 1.3-1.5) in homozygous carriers of R2 and 2.8 (95% CI = 2.5-3.1) in controls (p < 0.00001). In an APC resistance test which quantifies the cofactor activity of FV in APC-catalyzed FVIII(a) inactivation, homozygous R2-carriers had significantly lower (p < 0.00001) APC sensitivity ratios (APCsr = 1.54, 95% CI = 1.48-1.60) than controls (APCsr = 2.17, 95% CI = 2.05-2.28). This indicates that R2-FV has reduced cofactor activity in APC-catalyzed FVIII(a) inactivation. The changes of the relative amounts of FV1 and FV2 in carriers of the R2-gene will result in increased thrombin formation in the presence of APC and may provide a mechanistic explanation for the increased thrombotic risk associated with the R2-haplotype.

Activated Protein C Resistance↗
PubMed2001

A missense mutation (Y1702C) in the coagulation factor V gene is a frequent cause of factor V deficiency in the Italian population.

BACKGROUND AND OBJECTIVES: Factor V (FV) deficiency is a rare bleeding disorder whose molecular bases are poorly characterized. We have recently described a FV missense mutation (Y1702C) predicting reduced FV levels in a thrombophilic patient and in a healthy individual. The aim of the present work was to assess the prevalence of the FV Y1702C mutation among subjects with FV deficiency. DESIGN AND METHODS: Carriership of the FV Y1702C mutation was tested in 8 patients with severe FV deficiency (FV:C <8%), in 16 individuals with asymptomatic partial FV deficiency (mean FV:C 38.0%, SD 11.6%) and in 9 patients with pseudo-homozygous APC-resistance (mean FV:C 46.2%, SD 3.6%). An AccI-restriction protocol was employed for rapid mutation screening. RESULTS: The FV Y1702C mutation was detected in two unrelated patients with unmeasurable FV levels (one being homozygous and the other doubly heterozygous for a still unknown mutation) and in one subject with partial FV deficiency (FV:C 30%). A striking difference in bleeding phenotype was observed between the homozygous patient and her asymptomatic brother with the same FV genotype. A multi-point FV haplotype analysis was performed in all unrelated carriers of the FV Y1702C mutation. Three haplotypes were found to underlie the mutation in different individuals, suggesting that it might have arisen independently more than once. INTERPRETATION AND CONCLUSIONS: FV Y1702C is a common cause of FV deficiency in the Italian population and might be a recurrent mutation.

Adolescent↗
PubMed2000

An ab initio study of the photochemical decomposition of 3, 3-dimethyldiazirine

Photochemical decomposition of 3,3-dimethyldiazirine (DMD) has been computationally investigated by using high-level ab initio calculations in conjunction with the 6-31G and cc-pvdz basis sets. The geometries of minima and transition states, as well as conical intersection points in the seam of crossing of two surfaces, have been optimized with the complete active space self-consistent field (CAS-SCF) method, and their energies, recalculated with second-order multireference perturbation (CAS/MP2) theory. The reaction path starting at the excited n-pi state of DMD is predicted to occur via a nonadiabatic mechanism, giving carbene and molecular dinitrogen (both in their singlet ground states) as the main products; the computed barrier height (1.0 kcal mol(-)(1)) agrees well with the experimental estimate of the activation energy in the singlet excited state (0.0-1.5 kcal mol(-)(1)). Ground state of dimethylcarbene is the only species where a 1,2-hydrogen shift takes place, being the only source of propene. The calculated potential energy barrier height for dimethylcarbene to propene isomerization (2.6 kcal mol(-)(1)) agrees well with the observed activation energy (2.56 kcal mol(-)(1)). No evidence for rearrangement in the first singlet excited state of DMD has been found; such a process would lead to a higher activation energy than the observed one. Consequently, 1,2-hydrogen migration concurrent with N(2) extrusion in the excited state has been ruled out.

Journal Article↗
PubMed2000

Polymorphisms in the factor VII gene and the risk of myocardial infarction in patients with coronary artery disease.

BACKGROUND: High plasma levels of coagulation factor VII have been suggested to be predictors of death due to coronary artery disease. Since polymorphisms in the factor VII gene contribute to variations in factor VII levels, such polymorphisms may be associated with the risk of myocardial infarction, which is precipitated by thrombosis. METHODS: We studied a total of 444 patients, 311 of whom had severe, angiographically documented coronary atherosclerosis. Of these 311 patients, 175 had documentation of a previous myocardial infarction. As a control group, 133 patients with normal coronary arteriograms were also included. We measured the levels of activated factor VII and assessed three polymorphisms in the factor VII gene, one involving the promoter (A1 and A2 alleles), one involving the catalytic region (R353Q), and one involving intron 7. RESULTS: Each of the polymorphisms influenced factor VII levels. Patients with the A2A2 and QQ genotypes had the lowest levels of activated factor VII (66 percent and 72 percent lower, respectively, than the levels in patients with the wild-type genotypes). The frequencies of the various genotypes in the patients free of coronary artery disease were similar to those in the entire population of patients with coronary artery disease. In the latter group, there were significantly more heterozygotes and homozygotes for the A2 and Q alleles among those who had not had a myocardial infarction than among those who had had an infarction (P=0.008 for the presence of the promoter polymorphism and P=0.01 for the presence of the R353Q polymorphism by chi-square analysis). The adjusted odds ratio for myocardial infarction among the patients with the A1A2 or RQ genotype was 0.47 (95 percent confidence interval, 0.27 to 0.81). CONCLUSIONS: Our findings suggest that certain factor VII genotypes have a role in protection against myocardial infarction. This may explain why some patients do not have myocardial infarction despite the presence of severe coronary atherosclerosis.

Case-Control Studies↗
PubMed2000

Computational evidence in favor of a two-state, two-mode model of the retinal chromophore photoisomerization.

In this paper we use ab initio multiconfigurational second-order perturbation theory to establish the intrinsic photoisomerization path model of retinal chromophores. This is accomplished by computing the ground state (S(0)) and the first two singlet excited-state (S(1), S(2)) energies along the rigorously determined photoisomerization coordinate of the rhodopsin chromophore model 4-cis-gamma-methylnona-2,4,6,8-tetraeniminium cation and the bacteriorhodopsin chromophore model all-trans-hepta-2,4, 6-trieniminium cation in isolated conditions. The computed S(2) and S(1) energy profiles do not show any avoided crossing feature along the S(1) reaction path and maintain an energy gap >20 kcal small middle dotmol(-1). In addition, the analysis of the charge distribution shows that there is no qualitative change in the S(2) and S(1) electronic structure along the path. Thus, the S(1) state maintains a prevalent ionic (hole-pair) character whereas the S(2) state maintains a covalent (dot-dot) character. These results, together with the analysis of the S(1) reaction coordinate, support a two-state, two-mode model of the photoisomerization that constitutes a substantial revision of the previously proposed models.

Animals↗
PubMed2000

Combinations of 4 mutations (FV R506Q, FV H1299R, FV Y1702C, PT 20210G/A) affecting the prothrombinase complex in a thrombophilic family.

The study of the molecular bases of thrombophilia in a large family with 4 symptomatic members is reported. Three thrombophilic genetic components (FV R506Q, FV H1299R, and PT 20210G/A), all affecting the activity of the prothrombinase complex, were detected alone and in combination in various family members. In addition, a newly identified missense mutation (factor V [FV] Y1702C), causing FV deficiency, was also present in the family and appeared to enhance activated protein C (APC) resistance in carriers of FV R506Q or FV H1299R by abolishing the expression of the counterpart FV allele. The relationships between complex genotypes, coagulation laboratory findings, and clinical phenotypes were analyzed in the family. All symptomatic family members were carriers of combined defects and showed APC resistance and elevated F1 + 2 values. Evidence for the causative role of the FV Y1702C mutation, which affects a residue absolutely conserved in all 3 A domains of FV, factor VIII, and ceruloplasmin, relies on (1) the absolute cosegregation between the mutation and FV deficiency, both in the family and in the general population; (2) FV antigen and immunoblot studies indicating the absence of Y1702C FV molecules in plasma of carriers of the mutation, despite normal levels of the FV Y1702C messenger RNA; and (3) molecular modeling data that support a crucial role of the mutated residue in the A domain structure. These findings help to interpret the variable penetrance of thrombosis in thrombophilic families and to define the molecular bases of FV deficiency. (Blood. 2000;96:1443-1448)

Amino Acid Sequence↗
PubMed2000

Modulation of factor VII levels by intron 7 polymorphisms: population and in vitro studies.

Previous studies have established that factor VII gene (F7) polymorphisms (5'F7 and R353Q) contribute about one-third of factor VII (FVII) level variation in plasma. However, F7 genotyping in patients with cardiovascular disease has produced conflicting results. Population and expression studies were used to investigate the role of intron 7 (IVS7 ) polymorphisms, including repeat and sequence variations, in controlling activated FVII (FVIIa) and antigen (FVIIag) levels. Genotype-phenotype studies performed in 438 Italian subjects suggested a positive relation between the IVS7 repeat number and FVII levels. The lowest values were associated with the IVS7 + 7G allele. The screening of 52 patients with mild FVII deficiency showed an 8-fold increase in frequency (8%) of this allele, and among heterozygotes for identical mutations, lower FVII levels were observed in the IVS7 + 7G carriers. This frequent genetic component participates in the phenotypic heterogeneity of FVII deficiency. The evaluation of the individual contribution of polymorphisms was assisted by the expression of each IVS7 variant, as a minigene, in eukaryotic cells. The novel quantitative analysis revealed that higher numbers of repeats were associated with higher mRNA expression levels and that the IVS7 + 7G allele, previously defined as a functionally silent polymorphism, was responsible for the lowest relative mRNA expression. Taken together, these findings indicate that the IVS7 polymorphisms contribute to the plasmatic variance of FVII levels via differential efficiency of mRNA splicing. These studies provide further elements to understand the control of FVII levels, which could be of importance to ensure the hemostatic balance under pathologic conditions.

Amino Acid Substitution↗
PubMed2000

Deletion mapping of the potyviral helper component-proteinase reveals two regions involved in RNA binding.

The Potyvirus helper component-proteinase (HC-Pro) binds nonspecifically to single-stranded nucleic acids with a preference for RNA. To delineate the regions of the protein responsible for RNA binding, deletions were introduced into the full-length Potato potyvirus Y HC-Pro gene carried by an Escherichia coli expression vector. The corresponding proteins were expressed as fusions with the maltose-binding protein, purified, and assayed for their RNA-binding capacity. The results obtained by UV cross-linking and Northwestern blot assays demonstrated that the N- and C-terminal regions of HC-Pro are dispensable for RNA binding. They also revealed the presence of two independent RNA-binding domains (designated A and B) located in the central part of HC-Pro. Domain B appears to contain a ribonucleoprotein (RNP) motif typical of a large family of RNA-binding proteins involved in several cellular processes. The possibility that domain B consists of an RNP domain is discussed and suggests that HC-Pro could constitute the first example of a plant viral protein belonging to the RNP-containing family of proteins.

ATP-Binding Cassette Transporters↗
PubMed2000

Gas-phase reactions of nitronium ions with acetylene and ethylene: an experimental and theoretical study

A comparative study of the gas-phase reactions of NO2+ with acetylene and ethylene was performed by using FT-ICR, MIKE, CAD, and NfR/ CA mass spectrometric techniques, in conjunction with ab initio calculations at the MP2/6-31+G* level of theory. Both reactions proceed according to the same mechanism, that is, 1,3-dipolar cycloaddition, but yield products of different stability. The C2H2NO2+ adduct from acetylene has an aromatic character and hence is highly stabilized with respect to the C2H4NO2+ adduct from ethylene. Both cycloadducts tend to isomerize into O-nitroso derivatives, that is, nitrosated ketene and nitrosated acetaldehyde, which represent the thermodynamically most stable products from the addition of NO2+ to acetylene and ethylene, respectively. As prototypal examples of the reactivity of free nitronium ions with most simple pi systems, the reactions investigated are useful starting points to model the mechanism of aromatic nitration.

Journal Article↗
PubMed2000

Maternal antibody passively transferred interferes with rabies vaccination in hamsters.

Transference and interference of maternal immunity to offspring after rabies vaccination were studied in hamsters. Females were vaccinated or not before mating and offspring were vaccinated at the age of 7, 14, 21 and 30 days. Other pups were maintained as controls. Thirty days after vaccination pups were challenged intracerebrally with CVS virus. Mouse neutralization tests were used to verify antibody titers. Mortality of 97.0, 76.9, 60.9 and 24.0% was observed in pups vaccinated at 7, 14, 21 and 30 days respectively, born from vaccinated dams, while in pups from non-vaccinated dams, mortality was 51.4, 28.6, 8.7 and 0.0%. Statistically significant associations were found between mortality and age at vaccination, by simple linear regression with y=-3.1169x + 120.8 (p = 0.008; r2=0.98) for litters vaccinated and born from vaccinated dams and y=-2.2541x + 62.7495 (p = 0.03; r2=0.93) for pups vaccinated and born from non-vaccinated dams. Immunological response to vaccination in pups born from vaccinated mothers was delayed 11 days, when compared to that observed in pups of non-vaccinated mothers.

Age Factors↗
PubMed2000

The rôle of time in reducing gingival overgrowth in heart-transplanted patients following cyclosporin therapy.

BACKGROUND, AIMS: In a previous cross-sectional study, the relevant rôle of time in reducing gingival overgrowth (GO) in heart-transplanted patients undergoing Cyclosporin A (CsA) therapy was hypothesized to explain the inverse relationship between GO and months since the graft. METHODS: In the present study, the relationship between GO and time was investigated prospectively in a group of 21 heart transplanted patients who have been regularly followed up to 48 months. RESULTS: 6 months after beginning CsA therapy (1st appointment), 7 out of 21 patients (33%) had clinical GO as confirmed by a hyperplastic index (HI) >30. There was no significant difference between these values with respect to those detected during the 2nd appointment at 9 months. At this time, all patients underwent a regular oral hygiene program. Gingival and plaque indices significantly decreased at the 3rd appointment (12 months) both in the group of responders and in the group of non-responders and remained significantly unchanged with time; HI significantly decreased with time only in the group of responders, the decrease becoming significant 36 months after heart transplantation. As a consequence, the number of responders decreased from 7 at the 1st appointment to 5 after 12 months, 4 after 24 months, 2 after 36 months following heart transplantation. CONCLUSION: The results suggest that GO necessarily develops in responders within 6 months from heart transplantation and in most subjects may be a time-related side-effect probably due to a progressive reduction in the sensitivity of the periodontum to CsA.

Adult↗
PubMed2000

Opposite deletions/duplications of the X chromosome: two novel reciprocal rearrangements.

Paralogous sequences on the same chromosome allow refolding of the chromosome into itself and homologous recombination. Recombinant chromosomes have microscopic or submicroscopic rearrangements according to the distance between repeats. Examples are the submicroscopic inversions of factor VIII, of the IDS gene and of the FLN1/emerin region, all resulting from misalignment of inverted repeats, and double recombination. Most of these inversions are of paternal origin possibly because the X chromosome at male meiosis is free to refold into itself for most of its length. We report on two de novo rearrangements of the X chromosome found in four hypogonadic females. Two of them had an X chromosome deleted for most of Xp and duplicated for a portion of Xq and two had the opposite rearrangement (class I and class II rearrangements, respectively). The breakpoints were defined at the level of contiguous YACs. The same Xp 11.23 breakpoint was found in the four cases. That of the long arm coincided in three cases (Xq21.3) and was more proximal in case 4 (Xq21.1). Thus class I rearrangements (cases 1 and 2) are reciprocal to that of case 3, whilst that of case 4 shares only the Xp breakpoint. The abnormal X was paternal in the three cases investigated. Repeated inverted sequences located at the breakpoints of rearrangements are likely to favour the refolding of the paternal X chromosome and the recombination of the repeats. The repeat at the Xp11 may synapse with either that at Xq21.3 or that at Xq21.1. These rearrangements seem to originate as the Xq28 submicroscopic inversions but they are identifiable at the microscopic level and result from a single recombination event.

Adolescent↗
PubMed2000

Progesterone, progestagens and the central nervous system.

Oestrogen, progestagens and androgens are able to modulate several brain functions. Receptors for gonadal steroids have been identified in several brain areas: amygdala, hippocampus, cortex, basal forebrain, cerebellum, locus coeruleus, midbrain rafe nuclei, glial cells, pituitary gland, hypothalamus and central grey matter. The mechanism of action of sex steroids at this level is similar to that observed in the peripheral target organs, including both genomic and non-genomic effects. The increased use of sex steroid hormone derivative therapies has lead to study of the biochemical and metabolic properties of the different progestin molecules available in hormonal therapies. In particular, experimental and clinical studies focused the attention of researchers on interactions between oestrogens and progestins in the neuroendocrine control of the brain functions and its clinical implications. Moreover, steroids are also synthesized de novo in the brain or may be derived from the conversion of blood-borne precursors, suggesting that the brain is also a source of steroids, named neurosteroids. Neurosteroids exert non-classical rapid actions as allosteric agonists of gamma-aminobutyric acid receptor A (GABA(A)) and also modulate classic neurotransmitters in the brain. In addition, progesterone derivatives, e.g. pregnanolone, and 3alpha 5alpha-OH THP (allopregnanolone) are synthesized de novo by astrocytes and oligodendrocites starting from cholesterol. Physiological or pathological modifications of the synthesis and release of neurosteroids play a relevant role in the control of brain function.

Animals↗
PubMed2000

Neuropeptides, neurotransmitters, neurosteroids, and the onset of puberty.

Puberty results from withdrawal of the "gonadostat" mechanisms and from increased gonadotropin sensitivity to GnRH. It has been hypothesized that GnRH release may be modulated by a non-steroid-mediated mechanism. Modifications of neuropeptides, neurotransmitters, and neurosteroids may underlie the onset of pubertal processes. Neuropeptides mainly involved in the control of GnRH release are opioids, neuropeptide Y (NPY), galanin, and corticotropin-releasing factor (CRF), whereas neurotransmitters are noradrenaline, dopamine, serotonin, melatonin and gamma-aminobutyric acid (GABA). Norepinephrine, epinephrine, and dopamine stimulate GnRH, whereas the effect of serotonin on hypothalamic-pituitary-ovarian axis seems to be norepinephrine-mediated. Neurosteroids are steroid hormones that bind to the GABA-A receptor, synthesized in the brain de novo or from blood-borne precursors. DHEA, a GABA-A antagonistic neurosteroid, and allopregnanolone, a GABA-A agonistic neurosteroid, may be important in the onset of gonadarche. In conclusion, the onset of puberty derives from the complex interplay among neuropeptides, neurotransmitters, and neurosteroids that occurs in the awakening of hypothalamic-pituitary-ovarian axis.

Animals↗
PubMed2000

Identification and functional analysis of the turnip yellow mosaic tymovirus subgenomic promoter.

Most plant viruses rely on the production of subgenomic RNAs (sgRNAs) for the expression of their genes and survival in the plant. Although this is a widely adopted strategy among viruses, the mechanism(s) whereby sgRNA production occurs remains poorly defined. Turnip yellow mosaic tymovirus (TYMV) is a positive-stranded RNA virus that produces an sgRNA for the expression of its coat protein. Here we report that the subgenomic promoter sequence of TYMV is located on a 494-nucleotide fragment, containing previously identified highly conserved sequence elements, which are shown here to be essential for promoter function. After duplication, the subgenomic promoter can be inserted into the coat protein open reading frame, giving rise to the in vivo production of a second sgRNA. It is suggested that this promoter can function when contained on a different molecule than viral genomic RNA. This interesting trait may be of general use for plant and plant virus research.

Capsid↗