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Biomedical subjects

N Russo

Publications and source records attributed to N Russo.

At least 19 recordsLinked to original sources
PubMed2007

On the copper(II) ion coordination by prion protein HGGGW pentapeptide model.

The interaction of the octapeptide domain of the prion protein with the transition-metal-ion Cu2+ was studied at the DFT level by using the HGGGW pentapeptide as a model to mimic the PHGGGWGQ octarepeat sequence. Ten complexes, in which the metal ion exhibits different coordinations, were considered. Our results indicate that the lowest-energy structure is characterized by a tetracoordinated metal center and that this tendency of the ion to assume the square planar geometry is strong enough to prevent the addition of a further water molecule in its coordination sphere. The role of tryptophan was found to cause a lowering of the system energy due to the stabilizing effect of the electrostatic interaction between the Trp aromatic indole and histidine imidazole rings.

Circular Dichroism↗
PubMed2006

LANL2DZ basis sets recontracted in the framework of density functional theory.

In this paper we report recontracted LANL2DZ basis sets for first-row transition metals. The valence-electron shell basis functions were recontracted using the PWP86 generalized gradient approximation functional and the hybrid B3LYP one. Starting from the original LANL2DZ basis sets a cyclic method was used in order to optimize variationally the contraction coefficients, while the contraction scheme was held fixed at the original one of the LANL2DZ basis functions. The performance of the recontracted basis sets was analyzed by direct comparison between calculated and experimental excitation and ionization energies. Results reported here compared with those obtained using the original basis sets show clearly an improvement in the reproduction of the corresponding experimental gaps.

Journal Article↗
PubMed2006

Adult home parenteral nutrition: a clinical evaluation after a 3-year experience in a Southern European centre.

AIM: To evaluate the current use of Home Parenteral Nutrition (HPN) in a Southern European region. SUBJECTS AND METHODS: A total of 159 (86 m, 73 f) HPN patients, mean age 60.1 +/- 14.2 years, BMI 18.8 +/- 3.3kg/m2, consecutively referred to the Artificial Nutrition outpatient Unit of the Federico II University Hospital in Naples (Italy), from January 2000 to December 2002 and treated for at least 4 weeks. Retrospective evaluation of baseline disease, indications and duration of HPN treatment, type of venous access, complications. RESULTS: In all, 140 (88%) were cancer and 19 (12%) noncancer patients. Main indications were carcinosis in 68 for total, and hypophagia/dysphagia in 62 patients for partial/integrative (to oral-enteral nutrition) HPN; mean duration of HPN was 81.45 +/- 110.86 days of treatment and infection rate 2.89% in the whole population and 2.66% in the 36 patients treated for more than 3 months. No other major complications have been observed. CONCLUSION: HPN is confirmed to be a safe and effective treatment when prescribed and administered by a trained team.

Adult↗
PubMed2005

The epsilon-sarcoglycan gene in myoclonic syndromes.

Mutations in the epsilon-sarcoglycan gene (SGCE) are associated with familial myoclonus dystonia, but the full spectrum of the phenotype may not be fully defined. We screened 58 individuals with a range of myoclonic/dystonic syndromes for SGCE mutations. We found mutations (three of them novel) in six (21%) of the 29 patients with essential myoclonus and myoclonic dystonia, but did not find mutations in the 29 patients with other phenotypes.

Age of Onset↗
PubMed2005

Newly developed basis sets for density functional calculations.

Optimized contracted Gaussian basis sets of double-zeta valence polarized (DZVP) quality for first-row transition metals are presented. The DZVP functions were optimized using the PWP86 generalized gradient approximation (GGA) functional and the B3LYP hybrid functional. For a careful analysis of the basis sets performance the transition metal atoms and cations excitation energies were calculated and compared with the experimental ones. The calculated values were also compared with those obtained using the previously available DZVP basis sets developed at the local-density functional level. Because the new basis sets work better than the previous ones, possible reasons of this behavior are analyzed. The newly developed basis sets also provide a good estimation of other atomic properties such as ionization energies.

Journal Article↗
PubMed2005

Interaction of cysteine with Cu2+ and group IIb (Zn2+, Cd2+, Hg2+) metal cations: a theoretical study.

The structure and energetics of complexes obtained upon interaction between cysteine and Zn2+, Cd2+, Hg2+ and Cu2+ cations were studied using quantum chemical density functional theory calculations with the 6-311++G** orbital basis set and relativistic pseudopotentials for the cations. Different coordination sites for metal ions on several cysteine conformers were considered. In their lowest energy complexes with the amino acid, the Zn2+ and Cd2+ cations appear to be three-coordinated to carbonyl oxygen, nitrogen and sulfur atoms, whereas the Cu2+ and Hg2+ ions are coordinated to both the carbonyl oxygen and sulfur atoms of one of the zwitterion forms of the amino acid. Bonds of metal cations with the coordination sites are mainly ionic except those established with sulfur, which show a small covalent character that become most significant when Cu2+ and Hg2+ are involved. The order of metal ion affinity proposed is Cu>Zn>Hg>Cd.

Cadmium↗
PubMed2005

Spinal subarachnoid hematomas: our experience and literature review.

STUDY DESIGN: Spinal subarachnoid hematomas are unusual and difficult to diagnose and the outcome of treatment is influenced by the lesions that frequently accompany them. OBJECTIVES: To clarify the neuroradiological diagnostic aspects of spinal subarachnoid hematoma as well as the results of treatment. BACKGROUND: Only recently has subarachnoid hematoma been clearly distinguished from more common subarachnoid hemorrhage and its characteristics have still not been dealt with in detail. METHODS: A total of 69 cases (3 personal case, 66 published cases) were revised in terms of etiology, diagnostic imaging and the results of both surgical and conservative treatment. RESULTS: The most common causes of spinal subarachnoid hematoma are coagulopathies (either pharmacologically-induced or resulting from systemic diseases) (40.5%), lumbar puncture for diagnostic or anesthesiological purposes (44.9%) and traumatic injuries (15.9%): these factors may be present singly or variously combined. They may be spontaneous (17.3%) or, in rare cases, associated with aortic coarctation or degenerative vascular diseases. Overall mortality is 25.7%. In the 50 cases in whom long-term follow-up was possible, the outcome of treatment, which is almost exclusively always surgical, was good in 93.5% of 31 patients in whom neurological status on admission was satisfactory and in 15.8% of 19 cases with severe neurological deficits. CONCLUSIONS: MRI and CT are not usually diagnostic because they are not able to differentiate between a subarachnoid lesion and a subdural one. However, diagnosis may be possible when these investigations detect the CSF or the contrast medium surrounding the hematoma. Although the risks of producing spinal subarachnoid hematoma as a result of LP are remote, this is, in fact, the primary cause in patients with coagulopathies. The results of treatment depend on the patient's initial neurological condition, the severity of any concomitant pathologies, the position of the hematoma and the eventual association of a subdural hematoma.

Aged↗
PubMed2005

Theory of mind deficits in children with fragile X syndrome.

BACKGROUND: Given the consistent findings of theory of mind deficits in children with autism, it would be extremely beneficial to examine the profile of theory of mind abilities in other clinical groups such as fragile X syndrome (FXS) and Down syndrome (DS). Aim The aim of the present study was to assess whether boys with FXS are impaired in simple social situations that require them to understand their own and others' mental states - in essence: do they have a 'theory of mind'? METHOD: Well-standardized tasks of theory of mind, the location change false belief task and the appearance-reality tasks were employed to examine whether any impairment might be specific to the FXS or part of a more generalized developmental deficit. RESULTS: The results suggest that children with FXS do have impairment in theory of mind that is comparable to the deficit reported in other groups with learning disabilities such as DS. However, closer inspection of the impairment between these groups revealed qualitative differences in error types (realist vs. phenomenist), suggestive of atypical development that goes beyond general cognitive delay. CONCLUSION: The findings are discussed in terms of the teasing apart of different components of social cognition in order to identify syndrome-specific deficiencies and proficiencies.

Adolescent↗
PubMed2005

Brain metastasis from prostate cancer. Report of 13 cases and critical analysis of the literature.

Brain metastasis from prostate carcinoma occurs very rarely. We describe 13 patients with single brain metastasis from prostatic cancer. Total removal of the lesions was performed in ten patients. Three patients underwent stereotactic biopsy. All patients were treated with postoperative whole brain radiotherapy (WBRT). Eight patients died for systemic disease after a mean time of 9.2 months with a diagnosis of metastasis. Five patients are still alive at 20, 14, 11, 7 and 6 months, respectively. Even if brain metastasis from prostate cancer is often a terminal event with death occurring within few months from diagnosis, we suggest the same protocol (surgery and/or radiosurgery plus postoperative WBRT) usually adopted to treat brain metastasis from other primitive tumours. A non specific neurological symptomatology and a possible normal dosage of serum specific antigen may contribute to a delay in diagnosis. However, considering the rarity of brain metastasis from prostate carcinoma, standard brain MRI follow-up in men with prostatic cancer does not seem to be necessary yet.

Aged↗
PubMed2004

[Mud and baththerapy in the acne cure].

The skin, it is well know, is an organ of frontier and it is natural seat to natch, or collition, between exogenous stimoli and endogenous responses. Termal water and spud mud revelead their better potency on the skin and for that their tird close attention in dermatology. Our primary pourpose was to evalue eventuals modifications induced by thermal water and mud on healty skin and to know how their alter in significative mode functionals parameters, an alteration of which characterising pathogenetics events in development of acne. They are: follicular keratinisation, sebum synthesis by sebaceum glands, skin inflammation, loss of gate function of epidermidis. Results are showed.

Acne Vulgaris↗
PubMed2002

On the hardness evaluation in solvent for neutral and charged systems.

The influence of water on the hardness values of a series of neutral and charged molecules has been studied in the framework of density functional theory using the polarizable continuum model to take into account solvent effects. Three working formulas already widely tested in gas-phase have been used and the results compared. Two of the methods employed going from gas phase to solvent phase give values that do not change, while the results of the third method show remarkable changes. To check the reliability of the hardness behavior found, a test based on the hard-soft/acid-base principle and the calculation of the free energy of reaction has been applied using the adopted procedures.

Journal Article↗
PubMed2001

Potential energy surfaces for the gas-phase interaction between alpha-alanine and alkali metal Ions (Li+, Na+, K+). A density functional study.

The conformations of alpha-alanine and those of the eight most stable adducts that it forms with lithium, sodium, and potassium cations were studied by means of the density functional theory using the hybrid B3LYP exchange correlation potential and the 6-311++G basis set. Minima and transition states characterizing the energetic paths for the interaction of the three metal ions with the free amino acid were explored in detail, and the results show that they are almost the same in the cases of lithium and sodium ions. At the absolute minimum, the Li+ and Na+ cations appear to be contemporaneously linked to the carbonyl oxygen and nitrogen atoms of alpha-alanine. Slight differences were found for potassium; the most stable adduct has the cation coordinated to both oxygen atoms of carboxyl function. The influence of the low-energy conformers in the determination of the gas-phase absolute affinities is demonstrated.

Alanine↗
PubMed2001

Bond energies and attachments sites of sodium and potassium cations to DNA and RNA nucleic acid bases in the gas phase.

Gas-phase metal affinities of DNA and RNA bases for the Na(+) and K(+) ions were determined at density functional level employing the hybrid B3LYP exchange correlation potential in connection with the 6-311+G(2df,2p) basis set. All the molecular complexes, obtained by the interaction between several low-lying tautomers of nucleic acid bases and the alkali ions on the different binding sites, were considered. Structural features of the sodium and potassium complexes were found to be similar except in some uracil and thymine compounds in which the tendency of potassium ion toward monocoordination appeared evident. B3LYP bond energies for both metal ions were in agreement with the available experimental results in the cases of uracil and thymine for which the most stable complex was obtained starting from the most stable tautomer of the free nucleic acid base. For adenine, although the interaction of the ions with the most stable free tautomer generated the least stable molecular complex, the best agreement with experiment was found in just this case. For the remaining cytosine and guanine bases, our calculations indicated that the metal ion affinity value closest to experiment should be determined taking into account the role played by the different tautomers of the free bases with similar energy and all the possible complexes obtained by them.

Adenine↗
PubMed2001

Reaction of SC+(1D,3D) with H2O, NH3, and CH4: a density functional study.

Density Functional Theory has been used to explore quantitative details of the potential energy hypersurface for the insertion reaction of scandium ion into the O-H, N-H, and C-H bond of water, ammonia, and methane molecules leading to H2 elimination. Both singlet and triplet state channels have been considered. On the basis of the obtained results, it is possible to conclude that for the molecules considered the reaction is a spin-forbidden process. Indeed, it starts in the triplet ground state and ends in the singlet state, the change of the spin state probably occurring immediately after the formation of the electrostatic complex intermediate.

Journal Article↗
PubMed2001

Density functional computations of proton affinity and gas-phase basicity of proline.

The proton affinity and gas-phase basicity of proline were evaluated by using density functional theory coupling the B3-LYP hybrid functional with the extended 6--311++G** basis set. Cis and trans conformations of the carboxyl moiety for both exo and endo ring structures were considered for the neutral proline. The results show that the most stable structure of proline has the endo ring conformation with the carboxyl group in the cis position. The structure at the global minimum is stabilized by an intramolecular hydrogen bond. The nitrogen of the ring in the exo form is the preferred protonation site. The calculated proton affinity (924.3 kJ mol(-1)) and gas-phase basicity (894.4 kJ mol(-1)) are in very good agreement with the experimental counterparts.

Gases↗
PubMed2001

On the fragmentation pathway of the ionized enol of glycine in the gas phase.

Density functional and second-order many body perturbation approaches were used to compute the potential energy surface for the fragmentation of the ionized enol of glycine [H2NCH = C(OH)2]+* into water and aminoketene radical cation [H2N-HC = CO]+*. Two possible pathways were considered. The potential energy surfaces obtained are very similar and both predict the existence of a molecular complex in which the water is coordinated to the aminoketene moiety in two different fashions with a noticeable binding energy. The fragmentation is kinetically controlled by the step in which the molecular complex is formed from the most stable cation enol of glycine. Our quantum-mechanical data confirm the hypothesis that the ylide ion [H3NCHCOOH]+* is an intermediate in the water loss.

Journal Article↗
PubMed2000

In vitro evolution of a dimeric variant of human pancreatic ribonuclease.

Site-directed mutagenesis of human pancreatic RNase (HP-RNase) was used as a model system for investigating the genetic events underlying the evolutionary origins of protein oligomers. HP-RNase is a monomeric enzyme with no natural tendency to oligomerize (K(d) for any dimers in solution of >280 mM). Nevertheless, deletion of five amino acid residues in the loop linking the N-terminal helix of HP-RNase to the rest of the protein was found to drive polypeptide chains to fold into dimers. These dimers could not be dissociated by heating at 70 degrees C, and small amounts of monomer were detected only in highly diluted samples. Measurement of dimer and monomer concentrations under equilibrium conditions yielded a K(d) of 1.5 microM. This implies that the deletion increases the protein propensity to dimerize at least 5.2 orders of magnitude. Moreover, the HP-RNase dimers were found to be over 4.6 orders of magnitude more stable than the dimers of bovine pancreatic RNase A obtained by lyophilization from acetic acid (K(d) > 73 mM). Cross-linking experiments with divinyl sulfone indicated that the HP-RNase dimers are stabilized by the exchange between subunits of their N-terminal helices. This generates composite active sites, i.e., each contributed by two subunit chains, that retain full enzymatic activity. Overall, these results show that a deletion of few residues in a key region of a monomeric protein can be the primary event irreversibly leading to oligomerization of the protein through the swap of a secondary structure element between protomers.

Amino Acid Sequence↗