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Biomedical subjects

M Speranza

Publications and source records attributed to M Speranza.

At least 19 recordsLinked to original sources
PubMed2006

Spatial cognition based on geometry and landmarks in the domestic chick (Gallus gallus).

Recent evidence suggest that encoding of spatial information based on extended surfaces may differ from encoding based on discrete arrays of local elements. Here we investigated the use of these different frames of reference in domestic chicks. Chicks were trained to search for food hidden under sawdust in the center of the floor of a square-shaped landmark array, with its center in coincidence with the center of a square-shaped enclosure. Displacement of the array to a corner caused a shift of searching behavior toward the array, the search activity spanning between the center of the arena and the center of the array. After changing distances between landmarks, chicks still searched in the central area. Asymmetries were apparent in chicks tested in monocular conditions, with left-eyed chicks being more affected by the overall enclosure and right-eyed chicks by local landmarks. These results suggest that chicks can use both distances from extended surfaces and local information provided by the landmarks of the array to orient in space. However, chicks do not seem to perceive the array as a whole configuration, rather they tend to rely only on single landmarks to locate the goal.

Animals↗
PubMed2006

Modelling neurotransmitter functions: a laser spectroscopic study of (1S,2S)-N-methyl pseudoephedrine and its complexes with achiral and chiral molecules.

Wavelength and mass resolved resonance-enhanced two photon ionization (R2PI) excitation spectra of (1S,2S)-N-methyl pseudoephedrine (MPE) and its complexes with several achiral and chiral solvent molecules, including water (W), methyl (R)-lactate (L(R)), methyl (S)-lactate (L(S)), (R)-2-butanol (B(R)), and (S)-2-butanol (B(S)), have been recorded after a supersonic molecular beam expansion and examined in the light of ab initio calculations. The spectral patterns of the selected complexes have been interpreted in terms of the specific hydrogen-bond interactions operating in the diastereomeric complexes, whose nature in turn depends on the structure and the configuration of the solvent molecule. The obtained results confirm the view that a representative neurotransmitter molecule, like MPE, "communicates" with the enantiomers of a chiral substrate through different, specific interactions. These findings can be regarded as a further contribution to modelling neurotransmitter functions in biological systems.

Butanols↗
PubMed2005

Chiral clusters in a supersonic beam: R2PI-TOF spectroscopy of diastereomeric carboxylic esters/(R)-(+)-1-phenyl-1-propanol complexes.

Wavelength and mass resolved resonance-enhanced two photon ionization (R2PI) excitation spectra of (R)-(+)-1-phenyl-1-propanol (P(R)) and its complexes with some chiral esters, i.e. methyl lactates (L(R) and L(S)), methyl 3-hydroxybutyrates (H(R) and H(S)), and methyl 2-chloropropionates (C(R) and C(S)), have been recorded after a supersonic molecular beam expansion and interpreted in the light of DFT calculations. The spectral features of the selected complexes were found to depend on the nature of hydrogen-bond interactions within the diasteromeric complexes, whose intensity in turn depends upon the structure and the configuration of the estereal moiety. The study further confirms resonant two-photon ionization spectroscopy, coupled with time-of-flight mass resolution (R2PI-TOF), as an excellent tool for gathering valuable information on the interactive forces in molecular clusters and for the enantiodiscrimination of chiral molecules in the gas phase.

Esters↗
PubMed2003

Binge eating behaviours, depression and weight control strategies.

The aim of this paper was to explore the relationships between depressive symptoms and weight control strategies in DSM-IV eating disordered patients with binge eating behaviours. We hypothesised that weight control strategies characterised by a loss of control, such as vomiting and purging, may be clinically associated with increased levels of depression. The study population consisted of 402 consecutive outpatients: 27 with binge eating/purging anorexia nervosa (AN-BN), 213 with purging bulimia nervosa (BN-P), 73 with non-purging bulimia nervosa (BN-NP), and 89 with binge eating disorder (BED). The severity of depression was measured using the Beck Depression Inventory (BDI), and binge eating behaviours were investigated using the self-report scale for bulimic behaviours. In the sample as a whole, the severity of depression significantly correlated with the severity of binge eating behaviours, but no significant differences were found in the severity of depression by diagnostic sub-types. In order to avoid the confounding erasing effect of time, a smaller sample of patients with a short history of binge eating behaviours was further explored. Furthermore, because weight control strategies and the eating disorder diagnostic sub-types overlapped imperfectly, the patients were compared on the basis of presence or absence of strategies reflecting an active attempt to master the weight gain due to bingeing behaviours. The patients adopting active control strategies (N = 14) had significantly less severe depressive symptoms than those adopting non-active weight control strategies (N = 39). Finally, the Authors discuss some hypotheses concerning the defensive role of weight control strategies and the impact of illness duration on the clinical expression of depression in eating disordered patients.

Adult↗
PubMed2002

Chiral discrimination of 2,3-butanediols by laser spectroscopy.

The resonance enhanced two-photon ionization time-of-flight (R2PI-TOF) excitation spectra of supersonically expanded complexes of isomeric 2,3-butanediols with a suitable chromophore, i.e. R-(+)-1-phenyl-1-propanol, represent powerful means for structurally discriminating the diol moiety and for investigating the nature of the intra- and intermolecular interactions involved in the complexes.

Journal Article↗
PubMed2001

Origin of diastereofacial selectivity in tertiary 2-adamantyl cations.

The intrinsic factors governing the diastereofacial selectivity of 2-methyl-5-X-2-adamantyl cations (X = F (I(F)), Si(CH(3))(3) (I(Si))) toward a representative nucleophile, i.e., methanol, have been investigated in the gas phase at 750 Torr and in the 20-80 degrees C temperature range. The kinetic results indicate that CH(3)OH addition to I(F) proceeds through tight transition structures (TS(F)(syn) and TS(F)(anti)) characterized by advanced C-O bonding. The same interactions are much less pronounced in the comparatively loose transition structures involved in the CH(3)OH addition to I(Si) (TS(Si)(syn) and TS(Si)(anti)). The experimental evidence indicates that the activation barriers for the anti addition to I(F) and I(Si) are invariably lower than those for the syn attack. Large adverse entropic factors account for the preferred syn diastereoselectivity observed in the reaction with I(F). Entropy plays a minor role in the much looser transition structures involved in the reaction with I(Si), which instead exhibits a preferred anti diastereoselectivity. Comparison of the above gas-phase results with related theoretical and solution data suggests that the diastereofacial selectivity of I(F) and I(Si) measured in solution arises in part from the differential solvation of the two faces of the pyramidalized ions.

Journal Article↗
PubMed2001

Troposelective substitutions in microsolvated systems.

The mechanism and the stereochemistry of the intracomplex "solvolysis" of the proton-bound complexes I(X)() between CH(3)(18)OH and (R)-(+)-1-aryl-ethanol (1(R)()(X)(); aryl = phenyl (X = H); pentafluorophenyl (X = F)) have been investigated in the gas phase in the 25-100 degrees C temperature range. The results point to intracomplex "solvolysis" as proceeding through the intermediacy of the relevant benzyl cation III(X)() (a pure S(N)1 mechanism). "Solvolysis" of I(H)() leads to complete racemization at T > 50 degrees C, whereas at T < 50 degrees C the reaction displays a preferential retention of configuration. Predominant retention of configuration is also observed in the intracomplex "solvolysis" of I(F)(). This picture is rationalized in terms of different intracomplex interactions between the benzylic ion III(X)() and the nucleophile/leaving group pair, which govern the timing of their reorientation within the electrostatic complex. The obtained gas-phase picture is discussed in the light of related gas-phase and solution data. It is concluded that the solvolytic reactions are mostly governed by the lifetime and the dynamics of the species involved and, if occurring in solution, by the nature of the solvent cage. Their rigid subdivision into the S(N)1 and S(N)2 mechanistic categories appears inadequate, and the use of their stereochemistry as a mechanistic probe can be highly misleading.

Journal Article↗
PubMed2001

Hindered inversion of chiral ion-dipole pairs.

O-Protonated S-(-)-1-phenyl-1-methoxyethane (IS) has been generated in the gas phase by CH3(2)Cl+ methylation of S-(-)-1-phenylethanol (1S). Detailed information on the reorganization dynamics of the intimate ion-dipole pair (IIS), arising from IS by C-O bond dissociation, is inferred from the kinetic study of the intramolecular inversion of configuration of IS vs its dissociation to alpha-methylbenzyl cation (III) and CH(3)OH. The behavior of IIS in the gas phase is compared to that observed in aqueous solutions, where the loss of optical activity of IS is prevented by exchange of the leaving CH3OH with the solvent shell. Hindered inversion of IS in solution is attributed to the operation of attractive interactions between the moving CH3OH moiety and the solvent cage which inhibit internal return in the intimate ion-dipole pair IIS. Similar interactions do not operate in the solvolysis of 18O-labeled 1S in aqueous acids, whose loss of optical activity efficiently competes with exchange of the leaving H2(18)O with the solvent shell.

Journal Article↗
PubMed2001

R2PI Study of intermolecular hydrogen bond in solvent-free chiral complexes.

One- and two-color, mass selected R2PI spectra of the S(1)<--S(0) transitions in the bare (+)-(R)-1-phenyl-1-ethanol (E(R)) and its complexes with different solvent molecules (solv) (-)-(R)-2-butanol (B(R)) or (+)-(S)-2-butanol (B(S)) and (-)-(R)-2-butylamine (A(R)) or (+)-(S)-2-butylamine (A(S)), have been recorded after a supersonic molecular beam expansion. The one-color R2PI excitation spectra of the diastereomeric complexes are characterized by significant shifts of their band origin relative to that of bare E(R). The extent and the direction of these spectral shifts are found to depend on the structure and the configuration of solv and are attributed to different short-range interactions in the ground and excited states of the complexes. In analogy with other diastereomeric complexes, the phenomenological binding energy of the homochiral cluster is found to be greater than that of the heterochiral one.

Journal Article↗
PubMed2001

Enantiodiscrimination of chiral alpha-aminophosphonic acids by mass spectrometry.

Diastereomeric clusters between first-group metal ions (M(+)) and chiral alpha-aminophosphonic acids (A and B) have been readily generated in the gas phase by electrospray ionization (ESI) and their fragmentation investigated by mass spectrometry. The complexes studied had the general formula [MA(S)B(2)](+) and [MA(R)B(2)](+), where M = H, Li, Na, or K, A(S) and A(R) are the two enantiomers of a given acid A, and B is a reference alpha-aminophosphonic acid of defined configuration. Collision-induced decomposition (CID) of [MA(S)B(2)](+) and [MA(R)B(2)](+) leads to fragmentation patterns characterized by [MAB](+)/[MB(2)] abundance ratios which depend on the configuration of ligand A. These different spectral features were correlated to the different stability of the diastereomeric [MA(S)B(2)](+) and [MA(R)B(2)](+) complexes in the gas phase. The results have been discussed in the light of MM2 Molecular Mechanics Force Field calculations.

Journal Article↗
PubMed2001

Psychoactive substance consumption in eating disorders.

Research investigating the comorbidity between eating disorders and substance-use disorders have reported positive but contrasting results. The aim of this study was to further explore this association by studying patterns of consumption of the entire range of psychoactive substances (alcohol, specific drugs, prescribed psychotropics) in a large sample (N=271) of eating-disorder DSM-IV subtypes. Results show that subjects suffering from anorexia of the restrictive type show significantly less drug-consumption behaviors and alcohol abuse and/or dependence disorders than purging anorexic and bulimic subjects. No difference was found in the total consumption of psychotropics among the four groups of eating disorders. However, more than half of eating-disorder subjects are regular consumers of psychotropics. Among these regular consumers, bulimics self-prescribe and increase their doses of psychotropics significantly more than anorexics. Features of impulsivity that are associated with purging and bulimic behaviors could play a specific role in these patterns of comorbidity and account for such differences.

Journal Article↗
PubMed2001

Obsessive compulsive disorders in eating disorders.

OBJECTIVE: The aim of this study is to explore current and lifetime prevalence of obsessive compulsive disorders (OCD) in eating disorder (ED) subgroups and subtypes defined by the DSM-IV and to study the chronology of appearance of these disorders taking into account the role played by denutrition. METHOD: Current and lifetime prevalence were investigated using the Mini International Neuropsychiatric Interview (MINI) and the Yale-Brown Obsessive Compulsive Scale in a sample of 89 DSM-IV ED patients (58 AN and 31 BN) and 89 matched controls. RESULTS: Current and lifetime prevalence of OCD in ED was significantly higher than in general population (15.7% and 19% vs. 0% and 1.1%, P<.05). Anorexic patients presented a slightly higher current and lifetime comorbidity than bulimic patients (19% and 22.4% vs. 9.7% and 12.9%, n.s.). Purging anorexia was the diagnostic subtype, which presented the higher prevalences (29% and 43%), followed by restrictive anorexia (16%) and purging bulimia (13%). In the great majority of cases (65%), OCD diagnosis preceded ED diagnosis. Finally, OCD current prevalence and Y-BOCS scores of underweight patients were not significantly higher than normal-weight patients, suggesting that there were only limited links between denutrition and obsessionality.

Journal Article↗
PubMed2000

Alexithymia and depression in eating disorders.

We compared alexithymia and depression ratings for non-hospitalized women meeting DSM-IV criteria for anorexia nervosa (n=32) and bulimia nervosa (n=32) to ratings for healthy women (n=74). Alexithymia was evaluated by the Toronto Alexithymia Scale (TAS-20) and depression by the Hospital Anxiety and Depression Scale (HAD). TAS and HAD scores were significantly higher in anorexic compared to bulimic patients, although these two scales were significantly and positively correlated (r=0.53, P=0.001). After taking depression into account as a confounding variable, rates of alexithymia did not vary according to the type of eating disorder (anorexia or bulimia).

Adolescent↗
PubMed2000

Short-range interactions within molecular complexes formed in supersonic beams: structural effects and chiral discrimination

One- and two-color, mass-selected R2PI spectra of the S1<--S0 transitions in the bare chiral chromophore R-(+)-1-phenyl-1-propanol (R) and its complexes with a variety of alcoholic solvent molecules (solv), namely methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, S-(+)-2-butanol, R-(-)-2-butanol, 1-pentanol, S-(+)-2-pentanol, R-(-)-2-pentanol, and 3-pentanol, were recorded after a supersonic molecular beam expansion. Spectral analysis, coupled with theoretical calculations, indicate that several hydrogen-bonded [R.solv] conformers are present in the beam. The R2PI excitation spectra of [R.solv] are characterized by significant shifts of their band origin relative to that of bare R. The extent and direction of these spectral shifts depend on the structure and configuration of solv and are attributed to different short-range interactions in the ground and excited [R.solv] complexes. Measurement of the binding energies of [R.solv] in their neutral and ionic states points to a subtle balance between attractive (electrostatic and dispersive) and repulsive (steric) forces, which control the spectral features of the complexes and allow enantiomeric discrimination of chiral solv molecules.

Journal Article↗
PubMed2000

[Pregnancy and drug abuse: current situation and therapeutic strategies].

Drug abuse, a general public health problem, concerns a growing number of the pregnant women. Pregnancy in a drug addict is a high risk condition. The prevention of neonatal and pediatric complications involving both organic and psychological conditions, requires early individual medical, psychological and social support adapted to each pregnant addict. The risk for the mother and the fetus warrant prescription of substitution therapy during pregnancy. Published results concerning pregnancies in women on substitution therapy have been encouraging and clearly show a decrease in maternal and fetal complications. These studies are however difficult to conduct and carry a certain number of biases related to the social and economical context of the patients and also to the type of drug abuse (multiple drugs, drug combinations, psychostimulants, smoking, alcohol).

Abnormalities, Drug-Induced↗
PubMed1999

Obsessive-compulsive symptoms as a correlate of severity in the clinical presentation of eating disorders: measuring the effects of depression.

Obsessive-compulsive symptoms have been related to severity in the clinical presentation of eating disorders, whereas the impact of depression on the correlations between their severity and the severity of eating disorders has not been investigated. This paper assesses the effects of depression in 42 adolescent patients who met DSM-IV criteria for anorexia nervosa or bulimia nervosa by using the Yale-Brown Obsessive Compulsive Scale (Y-BOCS), the Eating Disorder Inventory (EDI) and the Beck Depression Inventory (BDI). The results indicate that patients who show elevated obsessionality and compulsivity on the Y-BOCS display a significantly higher degree of disturbed attitudes and behaviours concerning eating than patients with limited obsessionality and compulsivity. However, when the effects of depression are considered, all the differences found disappear. Our study suggests that depression is more directly associated with the severity of eating disorders than obsessive-compulsive symptoms and that the intensity of obsessive-compulsive symptoms in eating disorders is influenced by the intensity of depression. The relations between obsessive-compulsive symptoms, depression and eating disorders are not known. Even so this study highlights the importance of assessing depression when using obsessive and compulsive symptoms as a correlate of severity in the clinical presentation of eating disorders.

Adolescent↗