Impact of different typologies of smoking on ovarian reserve and oocyte quality in women performing ICSI cycles: an observational prospective study.

OBJECTIVE: Within the last few years smoking activities, as well as infertility, have increased in Italy, and so has the consumption of alternative cigarette devices among women of childbearing age. The aim of this observational study was to evaluate the impact of the consumption of cigarettes and alternatives devices, such as electronic cigarettes and heat-not-burn (HnB) products, on infertile women performing in vitro fertilization (IVF), in specific on the quality of oocytes retrieved in women performing intracytoplasmic sperm injection (ICSI) cycles. PATIENTS AND METHODS: Prospective observational longitudinal study involving 410 women referring to the Reproductive Physiopathology and Andrology Unit, Sandro Pertini Hospital, Rome, from 2019-2022. All the women enrolled filled out an elaborate questionnaire investigating smoking consumption, before the beginning of ovarian stimulation by antagonist protocol, ovarian pick-up, and subsequent ICSI technique. The outcomes of the study were the evaluation of clinical and ICSI features between the groups of smokers and non-smokers: the number of retrieved oocytes, immature oocytes, and fertilization rate were confronted between the two groups and between cigarette smokers vs. e-cigarette and heat-not-burn (HnB) products smokers. RESULTS: Clinical parameters were comparable between the group of smokers compared to one of the non-smokers, except for anti-Müllerian hormone (AMH), which was statistically lower in smokers (p<0.05). Regarding IVF hormonal stimulations it appears that the total dose of gonadotropin was statistically lower in the non-smoker's group, compared to smokers (1850±860 UI vs. 1,730±780 p<0.05). Regarding ICSI techniques interestingly the number of oocytes retrieved was lower in the smokers' group compared to non-smokers (5.21±0.9 vs. 6.55±3.5, p<0.001), and the number of empty zona pellucida oocytes was statistically higher in the smokers' group (0.51±0.1 vs. 0.2±0.1, p<0.05). On the other hand, the fertilization rate (FR) was statistically higher in non-smokers compared to the smokers' group (72.16±3.05 vs. 68.12±2.21, p=0.03). Out of the 203 smokers, overall, any statistically significant difference, regarding ICSI results, has been found between the group of cigarette smokers, compared to the group of e-cigarettes plus HnB products smokers. CONCLUSIONS: Smoking negatively impacts human fertility, leading to a reduction of ovarian reserve and ovarian quality, which can negatively impact results in women performing ICSI cycles. Despite the limitation of the study, our results underline that consumption of cigarette alternative devices seems to have a similar negative impact on the quantity and quality of oocytes retrieved in ICSI cycles. Clinicians should emphasize the reduction of exposure to harmful substances derived from the combustion of tobacco smoking, as well as alternative devices, in women of childbearing age.

Characterization of epidermal growth factor-like domain 7 (EGFL7) expression in normal endometrium and in the endometrium of women with poor reproductive outcomes.

STUDY QUESTION: Could epidermal growth factor-like domain 7 (EGFL7) be a factor involved in the preparation of the endometrium for implantation and could its dysregulation be implicated in poor reproductive outcomes? SUMMARY ANSWER: EGFL7 is highly expressed in the endothelium and glandular epithelium throughout the menstrual cycle; it is upregulated by stromal cells in secretory phase and appears strongly reduced in endometrial biopsies and isolated stromal cells of women with unexplained recurrent pregnancy loss (uRPL) and recurrent implantation failure (RIF). WHAT IS KNOWN ALREADY: The secreted factor EGFL7, originally identified as a gene primarily expressed in endothelial cells, is also expressed by the mouse blastocyst and by mouse and human trophoblast cells. It regulates trophoblast migration and invasion by activating NOTCH1 signaling. NOTCH1 has been demonstrated to play a fundamental role in endometrial receptivity and its dysregulation may be involved in selected pregnancy complications characterized by altered endometrial receptivity, such as uRPL. STUDY DESIGN, SIZE, DURATION: This is an exploratory study for which 84 endometrial biopsies were collected from normally fertile women, as well as from women with uRPL and RIF. PARTICIPANTS/MATERIALS, SETTING, METHODS: Samples were collected from women in both the proliferative and secretory phases of the menstrual cycle and stratified into three sub-groups according to the patient clinical history: 20 fertile women (8 in proliferative and 12 in secretory phase), 41 women with uRPL (6 in proliferative and 35 in secretory phase), and 27 women with RIF (8 in proliferative and 19 in secretory phase). Immunohistochemistry, real-time PCR, and western blot analyses were performed to study the expression of EGFL7 and NOTCH1, as well as the NOTCH target genes. MAIN RESULTS AND THE ROLE OF CHANCE: Analysis of spatial and temporal distribution of EGFL7 in endometrial biopsies from fertile women revealed higher levels of EGFL7 in samples from the secretory phase compared to proliferative phase. The expected expression of EGFL7 in endothelial cells was shown as well as the novel, not previously reported, expression in endometrial glands and stromal cells. EGFL7 was significantly reduced in the endometrium of women with uRPL and RIF in the secretory phases and this was associated with a downregulation of the NOTCH1 signaling pathway. Human recombinant EGFL7 was able to activate the NOTCH1 signaling pathway in endometrial stromal cells (EndSCs) obtained from fertile women but not in cells from uRPL or RIF patients. EndSCs from fertile women and decidualized in vitro for three days showed an upregulation of EGFL7 expression, whereas cells obtained from women with uRPL and RIF and decidualized in vitro did not. LIMITATIONS, REASONS FOR CAUTION: This study was conducted with a relatively small number of patient samples. Although results are highly reproducible and consistent, additional observations from multicentric cohorts would strengthen the relevance of the data. Moreover, this is an in vitro study, which might only partially represent the in vivo conditions. WIDER IMPLICATIONS OF THE FINDINGS: Our results demonstrate for the first time that EGFL7 is new player involved in decidualization and provide new insights into the pathophysiology of selected implantation defects and early pregnancy complications. Our studies have revealed that alterations in EGFL7 expression and the consequent dysregulation of NOTCH signaling are potential underlying causes of RIF and uRPL. Our results might have therapeutic relevance, as the EGFL7/NOTCH pathway may represent a potential target for medical intervention. STUDY FUNDING/COMPETING INTEREST(S): This study has been supported by the Grant for Fertility Innovation 2017 (Merck KGaA). There are no competing interests to disclose. TRIAL REGISTRATION NUMBER: Not applicable.

Assessment of sexual and emotional distress in infertile couple: validation of a new specific psychometric tool.

BACKGROUND: The diagnosis of infertility strongly impacts on psychological and sexological couple health. In this regard, some feelings and psychological states were demonstrated in association with reproductive problems. Depression and anxiety are the most common psychopathologies associated with infertility, although also sexuality is strongly involved in infertility conditions. OBJECTIVES: The aim of this study is to develop a tool to probe and assess the emotional aspects, sexuality, and social relationships of the couple seeking medical care for infertility. MATERIALS AND METHODS: A self-reported questionnaire that we will refer to as SEIq (Sexuality and Emotions in Infertility questionnaire) was constructed and developed and, consequently, administered to 162 heterosexual couples (324 subjects) seeking help for reproductive problems. Hence, we performed a specific statistical analysis to assess and validate this new psychometric tool. RESULTS: About 60% of men and women (both partners in 43% of couples) declare that infertility has changed their life (Q10). Moreover, the incidence of sexual disorder declared by the subjects is quite rare in men (10%) but more frequent in women (29%) (p < 0.01). CONCLUSION AND DISCUSSION: The results of this pilot test show that the diagnosis of infertility impacts on the couple relationship affecting the emotional area, interpersonal relationships, and sexual functions of the couples. Moreover, the SEIq appears a valuable tool to coherently probe and relate sexological, psychological, relational, and emotive aspects in partners and couples facing the infertility diagnosis. The explorative factor analysis of SEIq data allows to understand the women, men, and couples' behavior in our sample, individuating a reduced set of factors, prone to an easier evaluation. On the whole, the psychometric evaluation through SEIq might be suitable for the couples during Assisted Reproductive Technologies treatments.

Understanding the biomimetic properties of gallium in Pseudomonas aeruginosa: an XAS and XPS study.

Pyochelin (PCH) is a siderophore (extracellular chelator) produced by the pathogenic bacterium Pseudomonas aeruginosa (PAO). PCH is implicated in iron (Fe3+) transport to PAO, and is crucial for its metabolism and pathogenicity. Due to the chemical similarity with Fe3+, gallium (Ga3+) interferes with vital iron-dependent processes in bacterial cells, thereby opening new perspectives for the design of specific metal-based antibacterial drugs. However, the structural basis for the Fe3+-mimetic properties of Ga3+ complexed with the PCH siderophore is still lacking. A precise knowledge of the coordination chemistry at the metal site is one of the topmost issues in the production of novel biomimetic metal-based drugs. Elucidation of this issue by means of a deep structural spectroscopic investigation could lead to an improved interference with, or a specific inhibition of, relevant biological pathways. For this reason, we applied Synchrotron Radiation induced X-ray Photoelectron Spectroscopy (SR-XPS) and X-ray Absorption Spectroscopy (XAS) to probe the electronic nature and coordination chemistry of Fe3+ and Ga3+ coordinative sites in PCH metal complexes. Combined XAFS and SR-XPS studies allow us to demonstrate that both Fe and Ga have the same valence state in Fe-PCH and Ga-PCH, and have the same octahedral coordination geometry. Moreover, a similar next neighbour distribution for Fe and Ga, resulting from the EXAFS data analysis, strongly supports similar coordination chemistry at the origin of the biomimetic behaviour of Ga.

Controlled, prospective, observational study on the efficiency and tolerability of a combination of potential Nrf2-inducing antioxidants and micronutrients as pre-treatment for ICSI in dyspermic patients with previous failure.

OBJECTIVE: To evaluate the efficiency of pre-treatment in dyspermic males in IVF couples with a combination of micronutrients, for the purpose of improving the fertilization rate, the implantation rate and the outcome of the pregnancy. PATIENTS AND METHODS: This controlled prospective clinical study was performed in two medically assisted reproduction centers. 59 males with mild oligo-astheno-teratospermia (OAT) were admitted to the study. All of them had a history of previous in vitro fertilization (IVF) attempts with female partners aged < 40 diagnosed having tubal or idiopathic infertility. The subjects upon enrolment underwent a semen test and afterward were treated with alpha lipoic acid and glutathione (Fertiplus SOD®, Idi-Pharma, Catania, Italy) for 4 weeks (short-term). The primary endpoints that were evaluated are the following: fertilization rate (mean fertilization), implantation rate and pregnancy rate. RESULTS: At the end of this study all the males (mean age 39.5 ± 5.1) reported in not having any side effects during the administration of Fertiplus. Their female partners (mean age 34.9 ± 4.5) underwent IVF using the ICSI technique. The number of oocytes retrieved and inseminated was not statistically different in comparison to previous attempts, but with the same number of oocytes treated, the fertilization rate per couple demonstrated statistically significant increase (p<0.001). We did not observe a percentage increase in evolutionary embryos, but we noticed an improvement in embryo quality per individual couple (p<0.001), associated with a net increase in the implantation rate per couple (p<0.001) in terms of clinical pregnancy. The estimated miscarriage risk after treatment was five times lower (p<0.001). CONCLUSIONS: Short-term treatment with micronutrients in dyspermic subjects can improve the reproductive outcome of the IVF procedure.

Microscopic biomineralization processes and Zn bioavailability: a synchrotron-based investigation of Pistacia lentiscus L. roots.

Plants growing on polluted soils need to control the bioavailability of pollutants to reduce their toxicity. This study aims to reveal processes occurring at the soil-root interface of Pistacia lentiscus L. growing on the highly Zn-contaminated tailings of Campo Pisano mine (SW Sardinia, Italy), in order to shed light on possible mechanisms allowing for plant adaptation. The study combines conventional X-ray diffraction (XRD) and scanning electron microscopy (SEM) with advanced synchrotron-based techniques, micro-X-ray fluorescence mapping (µ-XRF) and X-ray absorption spectroscopy (XAS). Data analysis elucidates a mechanism used by P. lentiscus L. as response to high Zn concentration in soil. In particular, P. lentiscus roots take up Al, Si and Zn from the rhizosphere minerals in order to build biomineralizations that are part of survival strategy of the species, leading to formation of a Si-Al biomineralization coating the root epidermis. XAS analysis rules out Zn binding to organic molecules and indicates that Zn coordinates Si atoms stored in root epidermis leading to the precipitation of an amorphous Zn-silicate. These findings represent a step forward in understanding biological mechanisms and the resulting behaviour of minor and trace elements during plant-soil interaction and will have significant implications for development of phytoremediation techniques.

Silver nanoparticles linked by a Pt-containing organometallic dithiol bridge: study of local structure and interface by XAFS and SR-XPS.

Silver nanoparticles (AgNPs) functionalized with an organometallic bifunctional thiol containing Pt(ii) centers, generated in situ from trans-trans-[thioacetyl-bistributylphosphine-diethynylbiphenyl-diplatinum(ii)], were synthesized with different sulphur/metal molar ratios (i.e. AgNPs-1 and AgNPs-2) with the aim to obtain nanosystems of different mean size and self-organization behaviour. AgNPs spontaneously self-assemble, giving rise to 2D networks, as previously assessed. In this work a deeper insight into the chemico-physical properties of these AgNPs is proposed by means of synchrotron radiation induced X-ray photoelectron spectroscopy (SR-XPS) and X-ray absorption fine structure spectroscopy (XAFS) techniques. The results are discussed in order to probe the interaction at the interface between a noble metal and a thiol ligand at the atomic level and the aim of this study is to shed light on the chemical structure and self-organization details of nanosystems. The nature of the chemical interaction between the dithiol ligand and the Ag atoms on the nanoparticle surface was investigated by combining SR-XPS (S2p, Ag3d core levels) and XAS (S and Ag K-edges) analysis. UV-visible absorption and emission measurements were also carried out on all samples and compared with TD-DFT calculations so as to get a better understanding of their optical behavior and establish the nature of the excitation and emission processes.

Effects of consumption of whole grain foods rich in lignans in healthy postmenopausal women with moderate serum cholesterol: a pilot study.

This study aims at investigating the effect of an experimental period of intake of whole grain foods rich in lignans as part of an habitual diet on the plasma and urinary excretion of enterolignans, the biomarkers of lipid metabolism and the immunological and antioxidant status in a group of postmenopausal women with moderate serum cholesterol. A randomized double-blind crossover study was completed on 13 subjects in 12-weeks after protocol approval of an ethical committee. The subjects consumed whole grain foods high in lignans (30 g/d of breakfast cereals or biscuits, etc., 80 g/d of whole grain pasta) or refined grain foods for 4 weeks, separated by a 2-weeks wash-out period. A modest hypocholesterolemic effect (p < 0.05) of the whole grain diet was observed and the intake of whole grain products rich in lignans was also associated with an increase in urinary enterodiol excretion (p < 0.05).

The amorphous Zn biomineralization at Naracauli stream, Sardinia: electron microscopy and X-ray absorption spectroscopy.

An amorphous Zn biomineralization ("white mud"), occurring at Naracauli stream, Sardinia, in association with cyanobacteria Leptolyngbya frigida and diatoms, was investigated by electron microscopy and X-ray absorption spectroscopy. Preliminary diffraction analysis shows that the precipitate sampled on Naracauli stream bed is mainly amorphous, with some peaks ascribable to quartz and phyllosilicates, plus few minor unattributed peaks. Scanning electron microscopy analysis shows that the white mud, precipitated in association with a seasonal biofilm, is made of sheaths rich in Zn, Si, and O, plus filaments likely made of organic matter. Transmission electron microscopy analysis shows that the sheaths are made of smaller units having a size in the range between 100 and 200 nm. X-ray absorption near-edge structure and extended X-ray absorption fine structure data collected at the Zn K-edge indicate that the biomineral has a local structure similar to hemimorphite, a zinc sorosilicate. The differences of this biomineral with respect to the hydrozincite biomineralization documented about 3 km upstream in the same Naracauli stream may be related to either variations in the physicochemical parameters and/or different metabolic behavior of the involved biota.

Versatile plug flow catalytic cell for in situ transmission/fluorescence x-ray absorption fine structure measurements.

A novel flow-through catalytic cell has been developed for in situ x-ray absorption spectroscopy (XAS) experiments on heterogeneous catalysts under working conditions and in the presence of a liquid and a gas phase. The apparatus allows to carry out XAS measurements in both the transmission and fluorescence modes, at moderate temperature (from RT to 50-80 °C) and low-medium gas pressure (up to 7-8 bars). The materials employed are compatible with several chemicals such as those involved in the direct synthesis of hydrogen peroxide (O2, H2, H2O2, methanol). The versatile design of the cell allows to fit it to different experimental setups in synchrotron radiation beamlines. It was used successfully for the first time to test nanostructured Pd catalysts during the direct synthesis of hydrogen peroxide (H2O2) in methanol solution from dihydrogen and dioxygen.

Interfacial magnetic coupling between Fe nanoparticles in Fe­Ag granular alloys.

The role of the interface in mediating interparticle magnetic interactions has been analysed in Fe50Ag50 and Fe55Ag45 granular thin films deposited by the pulsed laser deposition technique (PLD). These samples are composed of crystalline bcc Fe (2­4 nm) nanoparticles and fcc Ag (10­12 nm) nanoparticles, separated by an amorphous Fe50Ag50 interface, occupying around 20% of the sample volume, as determined by x-ray diffraction (XRD), x-ray absorption spectroscopy (XAS), and high resolution transmission electron microscopy (HRTEM). Interfacial magnetic coupling between Fe nanoparticles is studied by dc magnetization and x-ray magnetic circular dichroism (XMCD) measurements at the Fe K and Ag L2,3 edges. This paper reveals that these thin films present two magnetic transitions, at low and high temperatures, which are strongly related to the magnetic state of the amorphous interface, which acts as a barrier for interparticle magnetic coupling.

Nature of "disorder" in the ordered double perovskite Sr2FeMoO6.

The degree of B/B;{'} alternate cation order is known to heavily influence the magnetic properties of A_{2}BB;{'}O_{6} double perovskites although the nature of such disorder has never been critically studied. Our detailed x-ray absorption fine structure studies in conjunction with synchrotron radiation x-ray diffraction experiments on polycrystalline Sr_{2}FeMoO_{6} samples with various degrees of disorder reveal that a very high degree of short range order is preserved even in samples with highly reduced long range chemical order. Based on these experimental results and with the help of detailed structural simulations, we are able to model the nature of the disorder in this important class of materials and discuss the consequent implications on its physical properties.

Local structure of Sr(2)FeMo(x)W(1-x)O(6) double perovskites across the composition-driven metal to insulator transition.

Sr(2)FeMoO(6) oxides exhibit a half-metallic ferromagnetic (HM-FM) ground state and peculiar magnetic and magnetotransport properties, which are interesting for applications in the emerging field of spintronics and attractive for fundamental research in the field of heavily correlated electron systems. Sr(2)FeWO(6) is an insulator with an antiferromagnetic (I-AFM) ground state. The solid solutions Sr(2)FeMo(x)W(1-x)O(6) also have peculiar properties-W doping enhances chemical order which allows stabilization of the HM-FM state; as the W content exceeds a certain value a metal to insulator transition (MIT) occurs. The role of W in determining the physical properties of Sr(2)FeMo(x)W(1-x)O(6) systems has been a matter of intense investigation. This work deals with the problem of the structural and electronic changes related to the MIT from a local perspective by means of x-ray absorption spectroscopy (XAS). This technique allows one to probe in detail the local structure and electronic modifications around selected absorber ions (W, Mo, Fe and Sr in our case). The results of XAS analysis in the whole composition range (0≤x≤1), in the near edge (XANES) and extended (EXAFS) regions, demonstrate an abrupt change of the local structure around the Fe and Mo sites at the critical composition, x(c). This change represents the microstructural counterpart associated with the MIT. Conversely, the local structure and electronic configuration of W ions remain unaltered in the whole composition range, suggesting indirect participation of W in the MIT.

Antiferromagnetic-paramagnetic insulating transition in Cr-doped V(2)O(3) investigated by EXAFS analysis.

We have performed extended x-ray absorption fine-structure (EXAFS) spectroscopy on a 2.8% Cr-doped V(2)O(3) sample, with the aim of studying its structural evolution in a wide temperature range across the paramagnetic-antiferromagnetic insulating phase transition at T(c). The data were registered with two different set-ups in fluorescence and transmission geometries, for polarized and unpolarized spectra, respectively. Our idea, based on previous experiments reported in the literature, is that extended structural modifications of the nominal trigonal symmetry are present in the paramagnetic insulating phase for several tens of degrees above T(c), involving further-nearest-neighbor vanadium ions. Our data confirm that the paramagnetic insulating phase is not structurally homogeneous in a temperature range of about 30 K around T(c), where local distortions of monoclinic symmetry involving further-nearest neighbors are present. Moreover, the analysis of the absorption profile at Cr K-edge suggests that Cr ions enter the lattice randomly. We finally analyze our findings in light of current theoretical models.

Crystallization on heating and complex phase behavior of alpha-cyclodextrin solutions.

Solutions composed of alpha-cyclodextrin (alpha-CD), water, and various methylpyridines, in particular, 4-methylpyridine (4MP), undergo reversible liquid-solid transitions upon heating, the crystalline solid phases undergoing further phase transformations at higher temperatures. This unusual behavior has been characterized by an ensemble of measurements, including solubility, differential scanning calorimetry, quasielastic neutron scattering, as well as x-ray powder diffraction. For the alpha-CD/4MP system five crystalline phases have been identified. The unit cell parameters and corresponding changes with temperature indicate a scenario for the crystallization process. A simple model is proposed that mimics the observed disorder-order transition.

[Periodontal pathology during pregnancy]. / Patologia del parodonto in corso di gestazione.

There is emerging evidence from the dental literature that periodontal disease may be a risk factor for systemic disease; in addition, several investigators report a link between periodontal infections and pregnancy complications. In the past few decades, major advances have been made in the elucidation of the etiology, pathogenesis and treatment of periodontal disease. These developments will be of importance to the obstetrician as periodontal disease may become a potential modifiable risk factor for pregnancy complications.

Microarchitectural and physical changes during fetal growth in human vertebral bone.

The ossification process in human vertebra during the early stage of its formation was studied by X-ray diffraction (XRD) and X-ray microtomography (microCT) at the European Synchrotron Radiation Facility (ESRF), Grenoble, France. Twenty-two samples taken from vertebral ossification centers of human fetal bone (gestational age ranging between 16 and 26 weeks) were investigated. The analysis of three-dimensional images at high spatial resolution (approximately 10 and approximately 2 microm) allows a detailed quantitative description of bone microarchitecture. A denser trabecular network was found in fetal bone compared with that of adult bone. The images evidenced a global isotropic structure clearly composed of two regions: a central region (trabecular bone) and a peripheral region (immature bone). XRD experiments evidenced hydroxyapatite-like crystalline structure in the mineral phase at any fetal age after 16 weeks. Interestingly, the analysis of XRD patterns highlighted the evolution of crystalline structure of mineralized bone as a function of age involving the growth of the hydroxyapatite crystallites.

Time-resolved X-ray powder diffraction on a three-way catalyst at the GILDA beamline.

Time-resolved X-ray diffraction experiments carried out at the beamline BM08-GILDA of ESRF allowed a study of the structural modifications taking place in a Pt/ceria-zirconia catalyst while the CO oxidation reaction was in progress. The capillary tube in which the sample is stored acts effectively as a chemical microreactor that ensures homogeneity of the sample treatments and minimization of diffusion effects. During the flowing of the reactant CO/He mixture, the investigated catalyst undergoes a fast Ce(IV)-Ce(III) partial reduction that involves the release of one O atom for every two reduced Ce cations. Because Ce(III) has a larger ionic radius than Ce(IV), the structural modification produces an increase of the lattice constant of the ceria-zirconia mixed oxide, and this increase is monitored by the translating imaging-plate device implemented at GILDA. The CO(2) resulting from the oxidation of the fluxed CO is monitored by a quadrupole mass spectrometer during the recording of the time-resolved X-ray diffraction pattern. The chemical and structural information was combined to show that the CO(2) yield is nearly constant until the catalytic system can provide oxygen for the reaction, while the structural rearrangement of the catalyst is delayed with respect to the switching on of the CO/He flux. After this induction time, during which CO(2) is produced with no structural modification of the catalyst, a fast increase of the lattice constant takes place.

An x-ray absorption spectroscopy study of the zinc environment in Langmuir-Blodgett phospholipid multilayers.

For the first time x-ray absorption spectroscopy was used to investigate the Zn environment in Langmuir-Blodgett multilayers. The multilayers were taken as a model of the multilamellar structure of the myelin sheath, the membrane surrounding the nerve axon, which plays a crucial role for signal transduction along the axon. The layers were assembled from the phospholipid dilauroylphosphatidic acid, both in the presence and in the absence of myelin basic protein. The analysis of the extended x-ray absorption fine structure and of the near edge regions of the x-ray absorption spectra at the Zn K-edge provided an accurate description of the local structure showing that the Zn ions are bound to the heads of the phospholipid molecules. The myelin basic protein induces a distortion on the Zn local environment due to a steric constraint but does not substitute the phosphate headgroups. These findings represent an important step in understanding the interplay among myelin basic protein, Zn, and the lipids of the myelin sheath.

Observation of the segregation and the dissolution of the Co and the Cu in CoCu metastable alloys.

Metastable Co(x)Cu100-x(x=5, 10, 15, 20) alloys have been annealed at increasing temperatures in order to study the evolution of the Co cluster and its relation with the magnetotransport properties. The structure was investigated by X-ray Absorption Spectroscopy on the Co K-edge as a function of composition and annealing temperature. An anomalous trend in the structural evolution has been evidenced and related to the preculiar features observed in the magnetotransport properties.