Temperature dependent local inhomogeneity and magnetic moments of (Li1-xFex)OHFeSe superconductors

We have combined the extended X-ray absorption fine structure (EXAFS) and X-ray emission spectroscopy (XES) to investigate the local structure and the local iron magnetic moments of (Li_1-xFe_x)OHFeSe (x∼0.2) superconductors. The local structure, studied by Fe K-edge EXAFS measurements, is found to be inhomogeneous that is characterized by different Fe-Se bond lengths. The inhomogeneous phase exhibits a peculiar temperature dependence with lattice anomalies in the local structural parameters at the critical temperature T_c (36 K) and at the spin density wave (SDW) transition temperature T_N (130 K). Fe Kβ XES shows iron to be in a low spin state with the local Fe magnetic moment evolving anomalously as a function of temperature. Apart from a quantitative measurement of the local structure of (Li_1-xFe_x)OHFeSe, providing direct evidence of nanoscale inhomogeneity, the results provide further evidence of the vital role that the coupled electronic, lattice and magnetic degrees of freedom play in the iron-based superconductors.

The CLEAR X-ray emission spectrometer available at the CLAESS beamline of ALBA synchrotron

The CLEAR X-ray emission spectrometer installed at the CLAESS beamline of the ALBA synchrotron is described. It is an energy-dispersive spectrometer based on Rowland circle geometry with 1 m-diameter circle. The energy dispersion is achieved by the combination of a diced analyzer crystal and a unidimensional detector. A single unconventional dynamically bent analyzer crystal (Si 111) permits a wide energy range to be covered, just by exploiting its different reflections (333, 444, 555, 777, 888): 6-22 keV, with a spectrometer efficiency that decreases above 11 keV because of the Si detector thickness (Mythen, 350 µm), while the relative scattering intensities for the Si 333, 444, 555, 777 and 888 reflections correspond to 36, 40, 21, 13 and 15, respectively. The provided energy resolution is typically below 1-2 eV and depends on the beam size, working Bragg angle and reflection exploited. In most cases the energy dispersion ranges from 10 to 20 eV and can be enlarged by working in the out-of-Rowland geometry up to 40 eV. The spectrometer works in full backscattering geometry with the beam passing through the two halves of the analyzer. The vacuum beam path and the particular geometry allow a typical average noise of only 0.5 counts per second per pixel. The spectrometer is mainly used for measuring emission lines and high-resolution absorption spectra, with a typical scanning time for highly concentrated systems of around half an hour, including several repeats. The intrinsic energy dispersion allows systematic collection of resonant X-ray emission maps by measuring high-resolution absorption spectra. Moreover, it allows spectra to be measured on a single-shot basis. Resonant inelastic X-ray scattering experiments to probe electronic excitations are feasible, although the spectrometer is not optimized for this purpose due to the limited energy resolution and scattering geometry provided. In that case, to minimize the quasi-elastic line, the spectrometer is able to rotate along the beam path. Advantages and disadvantages with respect to other existing spectrometers are highlighted.

Mn substitution effect on the local structure of La(Fe1-xMnx)AsO studied by temperature dependent x-ray absorption measurements

The local structure of La(Fe1-xMnx)AsO has been investigated using temperature dependent Fe K-edge extended x-ray absorption fine structure (EXAFS) measurements. The EXAFS data reveal distinct behavior of Fe-As and Fe-Fe atomic displacements with a clear boundary betweenx⩽ 0.02 andx> 0.02. The Fe-As bondlength shows a gradual thermal expansion while the Fe-Fe bond manifests a temperature dependent anomaly at ∼180 K forx> 0.02. It is interesting to find characteristically different nature of Fe-As and Fe-Fe bondlengths shown by the temperature dependent mean square relative displacements. Indeed, the Fe-As bond, stiffer than that of the Fe-Fe, gets softer forx⩽ 0.02 and hardly shows any change forx> 0.02. On the other hand, Fe-Fe bond tends to be stiffer forx⩽ 0.02 followed by a substantial softening forx> 0.02. Such a distinction has been seen also in the As K-edge x-ray absorption near edge structure, probing local geometry around As atom together with the valence electronic structure. The results suggest that local atomic displacements by Mn substitution inducing increased iron local magnetic moment that should be the main reason for its dramatic effect in iron-based superconductors.

Magnetosomes could be protective shields against metal stress in magnetotactic bacteria

Magnetotactic bacteria are aquatic microorganisms with the ability to biomineralise membrane-enclosed magnetic nanoparticles, called magnetosomes. These magnetosomes are arranged into a chain that behaves as a magnetic compass, allowing the bacteria to align in and navigate along the Earth’s magnetic field lines. According to the magneto-aerotactic hypothesis, the purpose of producing magnetosomes is to provide the bacteria with a more efficient movement within the stratified water column, in search of the optimal positions that satisfy their nutritional requirements. However, magnetosomes could have other physiological roles, as proposed in this work. Here we analyse the role of magnetosomes in the tolerance of Magnetospirillum gryphiswaldense MSR-1 to transition metals (Co, Mn, Ni, Zn, Cu). By exposing bacterial populations with and without magnetosomes to increasing concentrations of metals in the growth medium, we observe that the tolerance is significantly higher when bacteria have magnetosomes. The resistance mechanisms triggered in magnetosome-bearing bacteria under metal stress have been investigated by means of x-ray absorption near edge spectroscopy (XANES). XANES experiments were performed both on magnetosomes isolated from the bacteria and on the whole bacteria, aimed to assess whether bacteria use magnetosomes as metal storages, or whether they incorporate the excess metal in other cell compartments. Our findings reveal that the tolerance mechanisms are metal-specific: Mn, Zn and Cu are incorporated in both the magnetosomes and other cell compartments; Co is only incorporated in the magnetosomes, and Ni is incorporated in other cell compartments. In the case of Co, Zn and Mn, the metal is integrated in the magnetosome magnetite mineral core.

Temperature dependent local atomic displacements in NaSn2As2 system

NaSn₂As₂ is mechanically exfoliable layered van der Waals (vdW) Zintl phase that is getting interesting due to its low thermal conductivity and recently observed superconductivity. Here, we have investigated the temperature dependent local structure of NaSn₂As₂ by a combined analysis of As K-edge and Sn K-edge extended x-ray absorption fine structure measurements. The system is intrinsically disordered with the interatomic distances largely consistent to those estimated by average structure measurements. The stretching force constants of different bond distances have been determined using temperature dependent mean square relative displacements. The Sn-As distance is the strongest bond in this system, having covalent nature, unlike the weaker interlayer distances which are characterized by vdW type bonding. Among them, As-Na distance is slightly weaker than Sn-Sn(i) below  ∼200 K and tends to get stronger above this temperature. The anomalous behavior of As-Na bond suggests that the mechanical exfoliation in this system is likely to be temperature dependent. The anomaly in the interlayer atomic correlations may be due to a charge density wave-like instability around this temperature, indicated by earlier experiments. The local structure and disorder are discussed in relation to the physical properties of NaSn₂As₂.

A high-energy-resolution resonant inelastic X-ray scattering spectrometer at ID20 of the European Synchrotron Radiation Facility

An end-station for resonant inelastic X-ray scattering and (resonant) X-ray emission spectroscopy at beamline ID20 of ESRF - The European Synchrotron is presented. The spectrometer hosts five crystal analysers in Rowland geometry for large solid angle collection and is mounted on a rotatable arm for scattering in both the horizontal and vertical planes. The spectrometer is optimized for high-energy-resolution applications, including partial fluorescence yield or high-energy-resolution fluorescence detected X-ray absorption spectroscopy and the study of elementary electronic excitations in solids. In addition, it can be used for non-resonant inelastic X-ray scattering measurements of valence electron excitations.

High resolution x-ray absorption and emission spectroscopy of Li x CoO2 single crystals as a function delithiation

The effect of delithiation in Li _x CoO₂ is studied by high resolution Co K-edge x-ray absorption and x-ray emission spectroscopy. Polarization dependence of the x-ray absorption spectra on single crystal samples is exploited to reveal information on the anisotropic electronic structure. We find that the electronic structure of Li _x CoO₂ is significantly affected by delithiation in which the Co ions oxidation state tending to change from 3+  to 4+. The Co intersite (intrasite) 4p-3d hybridization suffers a decrease (increase) by delithiation. The unoccupied 3d t _2g orbitals with a _1g symmetry, containing substantial O 2p character, hybridize isotropically with Co 4p orbitals and likely to have itinerant character unlike anisotropically hybridized 3d e _g orbitals. Such a peculiar electronic structure could have significant effect on the mobility of Li in Li _x CoO₂ cathode and hence the battery characteristics.

A large-solid-angle X-ray Raman scattering spectrometer at ID20 of the European Synchrotron Radiation Facility

An end-station for X-ray Raman scattering spectroscopy at beamline ID20 of the European Synchrotron Radiation Facility is described. This end-station is dedicated to the study of shallow core electronic excitations using non-resonant inelastic X-ray scattering. The spectrometer has 72 spherically bent analyzer crystals arranged in six modular groups of 12 analyzer crystals each for a combined maximum flexibility and large solid angle of detection. Each of the six analyzer modules houses one pixelated area detector allowing for X-ray Raman scattering based imaging and efficient separation of the desired signal from the sample and spurious scattering from the often used complicated sample environments. This new end-station provides an unprecedented instrument for X-ray Raman scattering, which is a spectroscopic tool of great interest for the study of low-energy X-ray absorption spectra in materials under in situ conditions, such as in operando batteries and fuel cells, in situ catalytic reactions, and extreme pressure and temperature conditions.

Temperature dependent EXAFS study on transition metal dichalcogenides MoX2 (X = S, Se, Te)

The local structure of molybdenum dichalcogenide MoX2 (X  =  S, Se, Te) single crystal has been studied by means of multi-edge (Mo, Se, and Te K-edges) extended x-ray absorption fine-structure spectroscopy as function of temperature. The temperature dependences of the interatomic distances Mo-X, Mo-Mo and X-X (X  =  S, Se, and Te) and of the corresponding Debye-Waller factors have been extracted over the 70-500 K temperature range. Exploiting the correlated Einstein model, we found that the Einstein frequencies of Mo-X and X-X bonds obtained by present data are in close agreement with the frequencies of the optical (Raman and infrared) stretching modes for both MoS2 and MoSe2, whereas a significant deviation has been found for MoTe2. A similar anomaly has been found for the force constants related to the Mo-X bonds in the MoTe2 case. Our findings, accordingly with the results reported in a recent theoretical paper, support the idea that the optical vibrational modes have a dominant role in MoS2 and MoSe2, whereas the effects of acoustic vibrational modes cannot be neglected in the case of MoTe2.

A study of temperature dependent local atomic displacements in a Ba(Fe(1-x)Co(x))2As2 superconductor

We have studied the local structure of a Ba(Fe(1-x)Co(x))2As2 superconductor using temperature dependent extended X-ray absorption fine structure (EXAFS) measurements. Polarized EXAFS at the Fe K-edge on an optimally doped (x = 0.06) single crystal has permitted us to determine atomic displacements across the superconducting transition temperature (T(c)). The Fe-As bondlength hardly shows any change with temperature; however, the Fe-Fe sublattice reveals a sharp anomaly across T(c), indicated by a significant drop in mean square relative displacements, similar to the one known for cuprates and A15-type superconductors. We have also found a large atomic disorder around the substituted Co, revealed by polarized Co K-edge EXAFS measurements. The Co-Fe/Co bonds are more flexible than the Fe-Fe bonds with the As-height in Co-containing tetrahedra being larger than the one in FeAs4. The results suggest that the local Fe-Fe bondlength fluctuations and the atomic disorder in this sub-lattice should have some important role in the superconductivity of Ba(Fe(1-x)Co(x))2As2 pnictides.

Temperature dependent nanoscale atomic correlations in Ir1-xPtxTe2 (x = 0.0, 0.03 and 0.04) system

X-ray absorption near-edge structure (XANES) spectroscopy has been used to investigate the unoccupied electronic states and local geometry of Ir1-xPtxTe2(x = 0.0, 0.03 and 0.04) as a function of temperature. The Ir L3-edge absorption white line, as well as high energy XANES features due to the photoelectron multiple scatterings with near neighbours, reveal clear changes in the unoccupied 5d-electronic states and the local geometry with Pt substitution. We find an anomalous spectral weight transfer across the known first-order structural phase transition from the trigonal to monoclinic phase in IrTe2, which characterizes the reduced atomic structure symmetry below the transition temperature. No such changes with temperature are seen in the Pt substituted superconducting samples. In addition, a gradual increase of the spectral weight transfer is observed in IrTe2 with a further decrease in temperature below the transition, indicating that the low temperature phase is likely to have a symmetry lower than the monoclinic one. The results suggest that the interplay between inter-layer and intra-layer atomic correlations should have a significant role in the properties of an Ir1-xPtxTe2 system.

Is HE4 serum level a valid screening test in women candidates for kidney transplant? A case report and a review of literature

While studying a candidate for kidney transplant it is essential to exclude active malignant diseases. Serum biomarkers help to exclude specific cancers. Tumor markers are proteins secreted by neoplastic cells that can mark their activities. HE4 is a new tumor marker used in ovarian cancer. It is an epithelium protein that appears overexpressed in ovarian cancer, but it is also present in other normal human tissues. Often in patients with kidney failure serum biomarkers are increased compared to healthy people. We report a case of a Caucasian woman suffering from kidney failure examined by our team to be included on the kidney transplantation list. Patient had a known pelvic mass. Determination of serum biomarkers, CA125 and HE4, was performed to exclude pelvic tumor, and we found high levels of HE4 with normal levels of CA125. A new transvaginal ultrasound was performed on the patient and it showed a pelvic mass near the left ovary. This mass resulted bigger than in the previous ultrasound, performed about a month before. We decided to perform a pelvic CT for improved diagnostic accuracy. The reports of this exam showed that the mass was a hematoma correlated with a previous knee prosthetic surgery. Even tough many serum biomarkers are higher in patients with renal failure, there is no study to demonstrate that HE4 blood levels are modified in these patients. This case report shows how HE4 can be elevated in people in hemodialysis in a benign situation, also in a pelvic mass not from the genital tract. There is no similar case described in literature.

Temperature dependence of crystal field excitations in CuO

We report a study on the temperature dependence of charge-neutral crystal field (dd) excitations in cupric oxide, using nonresonant inelastic x-ray scattering spectroscopy. Thanks to a very high-energy resolution (ΔE = 60 meV), we observe thermal effects on the dd excitation spectrum fine structure between temperatures of 10-320 K. The spectra broaden considerably with increasing temperature, consistently with an enhancement of the coupling between crystal field excitations and the temperature-dependent continuum of states above the band gap. We discuss this and other mechanisms that may explain this temperature dependence.

Study of the electronic and magnetic properties as a function of isoelectronic substitution in SmFe(1-x)RuxAsO0.85F0.15

We have studied the electronic and magnetic properties of SmFe(1-x)RuxAsO0.85F0.15 (x = 0, 0.05, 0.25, 0.33, 0.5) by high-resolution x-ray absorption and x-ray emission spectroscopy. The local Fe magnetic moment (μ) tends to decrease for a small Ru substitution, but it shows a clear increase with further substitution. It appears that impurity scattering prevails in reducing the μ with small Ru substitution due to an extended Ru d-band. A nanoscale phase separation, that decouples the FeAs layers from the spacer layers, drives the increase of μ at higher Ru substitution. The results provide important information on nanoscale phase separation due to isoelectronic substitution in the active layers of iron-based 1111-superconductors and its effect on the local magnetic properties.

Abdominal emergency in elderly: a case of small bowel obstruction and ischemia caused by bulky IA ovarian cancer

Bowel obstruction resulting from colorectal and ovarian cancer is a serious and distressing complication of these malignancies. This may be caused by diffuse peritoneal carcinomatosis, bulky masses filling the pelvis and abdomen or postoperative adhesions, and should be carefully worked out by pre-operative imaging. We report the case of a small bowel obstruction and intestinal ischemia caused by a bulky (20x40 cm in diameter) cystic ovarian neoplasm that was found to be a stage IA G2 cystadenocarcinoma, successfully managed by uterus-sparing surgery.

Dispersive x-ray absorption studies at the Fe K-edge on the iron chalcogenide superconductor FeSe under pressure

The local structure and the electronic properties of FeSe under hydrostatic pressure were studied by means of dispersive x-ray absorption measurements at the Fe K-edge. The pressure dependence of the x-ray absorption near edge structure features seems to follow the behavior of the superconducting transition temperature Tc. The local structure, that has an important impact on the superconducting properties, appears to fall into two regimes: the pressure dependence of the Fe-Fe bond distance shows a clear change in the compressibility at p ∼ 5 GPa; in contrast, the Fe-Se bond distance decreases continuously with increasing pressure with a lower compressibility than the Fe-Fe bond. The results suggest that the pressure dependent changes in Tc of FeSe are closely related to the changes in local structure.

Electronic properties of FeSe(1-x)Te(x) probed by x-ray emission and absorption spectroscopy

The electronic structure of FeSe(1-x)Te(x) chalcogenide superconductors has been studied by x-ray emission (XES) and x-ray absorption (XAS) as a function of Te substitution. The Fe Kβ XES spectra reveal a relatively low spin state for Fe in FeSe(1-x)Te(x) superconductors, persisting in the whole range of Te substitution. The Fe K-edge high-resolution XAS shows systematic spectral changes due to the evolving hybridization between the Fe 3d (4p) and chalcogen p (d) orbitals. The resonant inelastic x-ray scattering (RIXS) spectra hardly show any feature except the one due to charge transfer from occupied to unoccupied bands, that changes substantially from FeSe to FeTe. The results provide important information on the electronic states and their evolution in the FeSe(1-x)Te(x) chalcogenides.

Local structure of LiCoO2 nanoparticles studied by Co K-edge x-ray absorption spectroscopy

We have studied the local structure of LiCoO(2) nanoparticles by Co K-edge x-ray absorption spectroscopy as a function of particle size. Extended x-ray absorption fine structure data reveal substantial changes in the near neighbor distances and the associated mean square relative displacements with decreasing particle size. X-ray absorption near edge structure spectra show clear local geometrical changes with decreasing particle size, similar to those that appear in the charging (delithiation) process. The results suggest that the LiCoO(2) nanoparticles are characterized by a large atomic disorder confined to the Co-O octahedra, similar to the distortions generated during the delithiation, and this disorder should be the primary limiting factor for a reversible diffusion of Li ions when nanoparticles of LiCoO(2) are used as cathode material in rechargeable Li ion batteries.

Large local disorder in superconducting K(0.8)Fe(1.6)Se2 studied by extended x-ray absorption fine structure

We have measured the local structure of superconducting K(0.8)Fe(1.6)Se(2) chalcogenide (T(c) = 31.8 K) by temperature dependent polarized extended x-ray absorption fine structure (EXAFS) at the Fe and Se K-edges. We find that the system is characterized by a large local disorder. The Fe-Se and Fe-Fe distances are found to be shorter than the distances measured by diffraction, while the corresponding mean square relative displacements reveal large Fe-site disorder and relatively large c-axis disorder. The local force constant for the Fe-Se bondlength (k ~ 5.8 eV Å(-2)) is similar to the one found in the binary FeSe superconductor, however, the Fe-Fe bondlength appears to be flexible (k ~ 2.1 eV Å(-2)) in comparison to the binary FeSe (k ~ 3.5 eV Å(-2)), an indication of partly relaxed Fe-Fe networks in K(0.8)Fe(1.6)Se(2). The results suggest a glassy nature for the title system, with the superconductivity being similar to that in the granular materials.

Isolated pancreatic tuberculosis: a diagnostic challenge

Abdominal tuberculosis is quite commonly found in miliary tuberculosis, especially in countries where TB is endemic, however the abdominal localization of tuberculosis in absence of disseminated disease is a rare condition and the involvement of the pancreas alone is extremely rare. Epidemiology of TB is changing in the latest years, often this illness is found in non-endemic regions and physicians are asked to interpret what happen when an old disease meets new diagnostic technologies. We describe the case of a young male admitted in our hospital for abdominal pain. Echotomography, CT scan and MRI showed a pancreatic mass suspected to be cancer and susceptible to surgical treatment, Endoscopic Ultrasound guided fine needle aspiration (FNA) showed isolated pancreatic tuberculosis.

Random alloy-like local structure of Fe(Se, S)(1-x)Te(x) superconductors revealed by extended x-ray absorption fine structure

The local structure of Fe(Se, S)(1-x)Te(x) ternary (11-type) chalcogenides has been studied by temperature dependent Fe K-edge extended x-ray absorption fine structure measurements. We find that the Fe-Se and Fe-Te distances in ternary FeSe(1-x)Te(x) are closer to the respective distances in the binary systems, revealing significant divergence of the local structure from the average one. The mean square relative displacements show a systematic change with Te content, consistent with bond relaxation in the inhomogeneous ternary phases. Also, the Fe-Te and Fe-S distances in the FeS(0.2)Te(0.8) ternary system are found to be different in the crystallographically homogeneous structure. The observed features are characteristic of ternary random alloys, suggesting that a proper consideration should be given to the atomic distribution for describing the complex electronic structure of these multi-band Fe-based chalcogenides.

A study of the electronic structure of FeSe(1-x)Te(x) chalcogenides by Fe and Se K-edge x-ray absorption near edge structure measurements

Fe K-edge and Se K-edge x-ray absorption near edge structure (XANES) measurements are used to study the FeSe(1 - x)Te(x) electronic structure of chalcogenides. An intense Fe K-edge pre-edge peak due to Fe 1s --> 3d (and admixed Se/Te p states) is observed, showing substantial change with Te substitution and x-ray polarization. The main white line peak in the Se K-edge XANES due to Se 1s --> 4p transition appears similar to the one expected for Se(2-) systems and changes with Te substitution. Polarization dependence reveals that unoccupied Se orbitals near the Fermi level have predominant p(x, y) character. The results provide key information on the hybridization of Fe 3d and chalcogen p states in the Fe-based chalcogenide superconductors.

Coherence motion perception in developmental dyslexia: a meta-analysis of behavioral studies

The magnitude of the association between developmental dyslexia (DD) and motion sensitivity is evaluated in 35 studies, which investigated coherence motion perception in DD. A first analysis is conducted on the differences between DD groups and age-matched control (C) groups. In a second analysis, the relationship between motion coherence threshold and reading ability is considered. Globally, the mean effect size (ES) is moderate (d = 0.675, 2334 subjects) with a large value (d = 0.747) for the between-groups differences in motion perception and a smaller mean ES (d = 0.178) for the correlational studies. The influence on ES of the stimuli parameters and subjects age is analyzed. The number of dots, the age of the subjects, and the type of analysis (i.e. between-group or correlational) are significantly related to the ES. Looking at the ES values, a smaller number of dots constituting the stimuli are associated with larger ES and, interestingly, the children studies are associated with lower ES in comparison with the researches evaluating adults. The large ES value supports the importance of studying motion perception deficits in DD groups, consistently with the claim that dorsal impairment/noise-exclusion deficit could be one of the risk factor of reading difficulties.

Traumatic complex wounds, multidisciplinary approach: our experience in a case series

"Limb-salvage" is a social problem that is rapidly increasing, both in Italy and in the rest of world. Today, as in earlier times, the main causes of open wounds are traumas and such injuries are mainly of II and III stage of Gustilo's classification. Nowadays, the use of modern techniques determined a further dramatic reduction in the infection rates and, above all, in the risk of limb amputation. The most important techniques include: V.A.C. therapy (vacuum assisted closure); PRP gel (platelet-rich plasma gel); hyperbaric oxygen therapy. We treated 4 patients with high energy acute trauma through the combined and innovative use of advanced dressings. The authors report their experience and a brief review of the literature as contribution in regards to treatment of complex wounds of the limbs.

Primary psoas abscess in a patient affected by acquired immunodeficiency syndrome: a rare case according to the reviewed literature

Abscesses of the psoas muscle can be divided into primary and secondary. In the primary ones, it is not possible to identify any further infected site. The localization to this muscle is due to its rich vascularization and Staphylococcus aureus is the most frequent aetiological agent of the infection. Treatment requires the use of appropriate antibiotics, as well as surgical or percutaneous drainage of the abscess. The percutaneous drainage is much less invasive and a low risk in the patients with acquired immunodeficiency syndrome, and is effective for draining even multiloculated abscess. The authors present a rare case of primary psoas abscess in patient affected by acquired human immunodeficiency syndrome, showing a mass in the inferior lumbar region through the lumbar triangle of Petit and fever. Treatment consisting in percutaneous drainage combined with systemic antibiotic administration was successful.

ERCP in total situs viscerum inversus

A 69-year-old cholecystectomized female with known total situs viscerum inversus presented recurrent colicky pain in the left upper abdominal quadrant and jaundice. Laboratory parameters showed increased neutrophils and coniugated bilirubin of 5.53 mg/dl. US and MRCP confirmed total situs viscerum inversus and a dilatation of the intra- and extrahepatic ducts with a peripapillary 13 mm stone. ERCP, sphincterotomy and successful common bile duct stone extraction were performed in the conventional way. ERCP was carried out successfully despite situs inversus maintaining the patient in the prone position with the endoscopist on the right side of the table. Some authors have reported similar cases in whom ERCP was performed in other positions, while this report shows that an experienced endoscopist can achieve the same results in the conventional way as it is possible when anatomical changes, Billroth II or Roux-en-Y, or different positions of the patient, supine or on the left side, are present.

Gastrointestinal bleeding in emergency setting: two cases of intestinal angiodysplasia and unusual conservative surgical treatment

The authors report two cases of gastrointestinal bleeding in an emergency setting caused by angiodysplasia of colon and small bowel. They stress the rarity of the lesion and consider the difficulties involved in obtaining a preoperative diagnosis. The optimal management is uncertain and depends on the severity and rate of bleeding. A conservative medical approach is indicated for many patients, while surgery constitutes definitive treatment in case of massive hemorrhage or recurrent bleeding. In the cases reported the diagnosis was performed only via intra-operative enteroscopy. An unusual conservative surgical treatment was performed based on ligation of the vascular elements of the angiodysplasia. This method makes it possible to avoid an intestinal resection and yelds good results.

Small bowel intussusception: what is the role of laparoscopy?

Small bowel intussusception in adults is a rare surgical disease which almost always occurs as a complication of either benign or malignant lesion of the bowel that is working as a leading point. In adults, the surgical approach consists of the resection of the bowel involved to ensure the excision of the lesion below. The authors report a case of ileocecal intussusception occurred in a young woman, 35 years old, observed for abdominal pain and signs of small bowel occlusion. She underwent surgical resection of the ileocecal segment with laparoscopic approach. The authors discuss the feasibility of the laparoscopic approach in this rare surgical disease and its benefits in terms of patient's postoperative comfort and outcome.

Role of extracellular matrix in regulation of staurosporine-induced apoptosis in breast cancer cells

Autocrine and paracrine mechanisms modulate the synthesis and secretion of extracellular matrix (ECM); moreover, each component of the ECM is capable of modulating the synthesis and release of other ECM molecules. Therefore, the synthesis of ECM glycoprotein fibronectin and laminin was studied in the human breast cancer cell lines MCF7 and MDA MB 23, plated on different ECM. Our results showed that the cells plated on a fibronectin substrate increased laminin synthesis: this event correlated with an increase in alpha2 and alpha3 integrin subunits. Staurosporine-induced apoptosis was then analyzed in the cell lines plated on different ECM. Staurosporine treatment determined the apoptosis of 35 and 33% respectively of MDA MB 231 and MCF7; these values increased to 60 and 64% in cells plated on laminin, to 48 and 63% in cells plated on fibronectin and to 64 and 69% in cells plated on matrigel. Moreover, staurosporine treatment decreased bcl-2 expression in the cells plated on fibronectin and laminin. Yet, staurosporine treatment determined PARP cleavage and PARP partial disappearance when the cells were plated on matrigel. Finally, a partial loss of function mutant Ras protein that activated only Raf pathway, was expressed in MCF7, in order to identify whether the increase of apoptosis induced by extracellular matrix involved the Raf/MAP kinase pathway. The increase of apoptosis of the cells plated on matrigel suggested that the activation of the Raf pathway is probably involved in the decrease of survival on matrigel. These data demonstrate that the modification of ECM modulates the apoptotic process of breast cancer cells and suggest that it is worthwhile to dissect the role of ECM in the control of apoptotic process.

Squamous and adenosquamous cell carcinomas of the gallbladder

Squamous and adenosquamous cell carcinomas (ASC and SCC) are rare subtypes of gallbladder cancer, traditionally considered more aggressive and with a poorer prognosis than adenocarcinoma. We report about two patients affected by an advanced squamous cell carcinoma of the gallbladder. Both had a large tumour in the gallbladder fossa region with infiltration of the liver. Surgical resection was radical in one, but palliative in the other. pTNM was T3 N0 M0, G3, R0 in the former and T3 N0 M0, G2 R1 in the latter. Patients died for local recurrence after 12 and 5 months, respectively. Natural history, clinical findings, prognosis and outcome of this rare gallbladder tumour are discussed on the basis of a review of the English literature. In conclusion, an aggressive and radical surgical treatment of advanced squamous and adenosquamous cell gallbladder carcinomas seems to be indicated for their low proclivity to distant spreading.

Acute appendicitis or something else? A case report of cecal endometriosis in emergency setting

Large Bowel is not uncommonly involved by extra pelvic endometriosis, however cecal localization is the lowest reported in literature; the differential diagnosis of intestinal endometriosis remains difficult, especially in those patients who underwent surgery in emergency setting. The Authors report a case of cecal endometriosis, operated on the basis of clinical signs of surgical abdomen. At laparotomy macroscopic appearance of the cecal lesion, suggesting a neoplastic mass, induced the equip to perform a right emicolectomy. The Authors discuss the clinical features and the role of surgery in management of extra pelvic endometriosis in emergency setting, in the light of the newest advances in medical treatment.

[Early diagnosis importance for a correct surgical treatment of PAES (popliteal artery entrapment syndrome)]

Popliteal artery entrapment syndrome (PAES) is an uncommon pathological entity, caused by segmental popliteal artery compression by the surrounding myofascial structures. Clinical symptoms may appear acutely, with temporary ischaemic attacks, or chronically, with concerned calf claudicatio intermittens and for 30% are bilateral. Diagnosis, besides being based on clinical objectivity (acute and deep pain to the struck limb, mainly during active plantar hyperextension) and history-taking (subject-age and lack of atherosclerosis), is based on ultrasonographic (eco-color Doppler of the aortic-iliac-femural-popliteal trunks, tensiometric Doppler), angio-RM, angio-CT scan and dynamic angiographic exams. Treatment, essentially, is surgical by simple freeing of the popliteal artery from surrounding myofascial structures or by autologous vein (saphenous v.) interposition grafting and patching, or bypass without vessel resection. About clinical case reported by the authors, 44-years female with left calf acute pain symptoms, cold skin by the thermo-touch, hypo-paraesthesia with fifth toe cyanosis and walking inability, surgical treatment, because of precox diagnosis, consisted of simple cut of myofibrous shoot starting from medial head of the left gastrocnemious muscle and compressing popliteal artery, with clinical chart complete resolution.

[Lipoma, lipoma-like, atypical lipoma: case report]

Lipoma, generally considered as a benign neoplasia, may occur as liposarcoma lipoma-like or atipycal lipoma, especially when of huge dimension. Pathological features of lipoma and liposarcoma lipoma-like are similar: the pattern is characterized by fatty lobules, with fibrosus septa. The presence of vartiable amount of atipical cell with hyperchromatic, solitary or multiple nuclei is suggestive of liposarcoma lipoma-like or atypical lipoma. The clinical features of these lesions are high rate of local recurrence and a low risk to metastasize. Preoperative work up, ultrasounds and MR have a poor diagnostic value, and no imaging features are so specific to differentiate between lipoma and liposarcoma lipoma-like, except site and size. The surgical treatment of the liposarcoma lipoma-like and atypical lipoma and the postoperative therapy, when required, should be performed in specialized centers. Only the combined approach, surgery and radiotherapy, can result in prevention of local recurrence and malignant transformation. The Authors report two cases of liposarcoma lipoma-like admitted to their Institution and review the Literature.

Advances in the understanding of malignant transformation of keratinocytes: an immunohistochemical study

AIM

We set out to investigate the interactions between malignant transformation of keratinocytes, presence of oncoproteins and immunosurveillance in squamous cell carcinoma (SCC) and in a preneoplastic lesion, actinic keratosis (AK).

METHODS

Samples of SCC, AK and normal skin (NS) were subjected to quantitative analysis using the following antibodies: anti-p53, Ki67, OKT6, OK-DR, B7/BB1, anti-CD54, anti-CD11, OKT3, OKT4, OKT8; positivity for ras-p21, EGFr and bcl-2 was evaluated by semiquantitative analysis.

RESULTS

Oncoprotein alterations and increased keratinocyte proliferative activity were observed both in AK and SCC. The number of Langerhans cells (CD1a+ cells) was similar in the two lesions but lower in SCC compared to AK. The proportion of CD1a(+)-B7/BB1+ cells was slightly higher in AK and SCC than in NS. The Langerhans cells expressed the HLA-DR antigen in all groups. Values were highest in AK and NS, and quite low in SCC. Cytotoxic T lymphocytes were more numerous in SCC than in AK and NS. Interestingly, the total CD4/CD8 ratio was much lower in SCC than in AK and NS, which indicates an increase in the CD8+ subpopulation in samples of SCC. In the epithelia of SCC samples there were a considerable number of B7/BB1+ keratinocytes.

CONCLUSIONS

We suggest that alterations in the immunodefence mechanisms have an important role in the transformation of AK into SCC, and that these changes affect not only lymphocytes, but also professional (i.e., Langerhans cells) and non-professional (i.e., keratinocytes) antigen presenting cells.

An experimental study in X-ray spectroscopy of the zirconium (Ca-PSZ) - bone interface. Microanalytic evaluation of the osteogenetic response

Ultrastructural difractometric and chemical evaluations of calcium partially stabilized zirconium (Ca-PSZ) implants were performed in an in vivo study on animals in order to evaluate its biological behaviour. The chemical-morphological investigations demonstrated the presence of an osteogenetic activity at the bone-biomaterial interface. The new-osteogenesis was preceded by the formation of a loose connective tissue around the implants. This mesenchymal-type tissue without a capsular organization, allowing modulation of the mechanical forces to which the implant is subject, could be considered a positive event in the osteogenetic process and not a sign of future failure of the implant. Finally, microanalytical investigations carried out on non-implanted and implanted Ca-PSZ tools suggested that the surface of this ceramic material does not undergo modification once it has been inserted in the biological environment (12 months).

In vitro study of gingival fibroblasts from normal and inflamed tissue: age-related responsiveness

The aim of this study was to characterize some phenotypic expressions of fibroblasts from the human oral mucosa. Gingival and lower forearm fibroblasts from young (20-30 years) and elderly (> 60 years) subjects were analyzed. Gingival fibroblasts were taken from donors with (P) and without (NP) periodontal disease, while skin biopsies were taken from healthy subjects. Cell proliferation was assessed by evaluating the cell multiplication coefficient (C.M.C.). The proliferation potential of gingival fibroblasts from elderly individuals with and without periodontopathy did not differ from that of young subjects in the same condition but differed significantly in the skin samples. Enzyme neutral endopeptidase (EC 3.4.24.11) (NEP) activity, studied as a possible marker of cell ageing, showed an age-related increase in human skin fibroblasts but not consistently in gingival fibroblasts from individuals with or without periodontal disease. Cell area and substrate adhesion were evaluated by morphometric analysis. There were no significant differences between elderly P and NP subjects, while significant differences were observed between young and elderly P subjects. In conclusion, proliferative capacity and NEP activity in gingival fibroblasts did not appear to be age-related, probably because their microenvironment is continually moistened by saliva, which continues to contain growth factors, notably EGF, even into senescence. Tissue reaction and repair are important clinical and therapeutic implications.

Biochemical-morphological modifications of platelet membranes during pregnancy-induced hypertension

A platelet (PLT) function modification has been reported in normal pregnancies compared with the nonpregnant condition and it has been hypothesized to play a central role in the pathogenesis of pregnancy-induced hypertension (PIH). The aims of the present study were (i) to evaluate the lipid composition, fluidity at different depths, transport functions, and ultrastructural features of the PLT membrane in PIH and (ii) to ascertain whether similar modifications may be determined by the state of pregnancy in comparison with the nonpregnant condition. The platelets of healthy pregnant women (HPW) showed: (i) an increase in Ca2+ ATPase activity, (ii) a decreased fluidity of the deeper site of the membrane, (iii) a reduced cholesterol concentration, with an increased ratio between unsaturated and saturated fatty acids; (iv) a decreased intramembranous particles (IMP) distribution factor (DF) of the plasma membrane E face in comparison with healthy nonpregnant women. When comparing women affected by PIH with HPW, we observed (i) reduced Na+/K+ ATPase activity and enhanced Ca2+ ATPase activity and intraplatelet calcium concentrations, (ii) an increased membrane fluidity, (iii) an increased cholesterol concentration and ratio between unsaturated and saturated fatty acids, (iv) a reduction of the IMP number and the DF. Pregnancy produces a deep modification of the platelet plasma membrane, and PIH produces a more pronounced alteration of the maternal platelets, which can be responsible for the observed modifications in placental blood flow and in the fetomaternal exchange.

Osteoconduction exerted by methylpyrrolidinone chitosan used in dental surgery

Surgical wounds from wisdom tooth avulsions were medicated with freeze-dried methylpyrrolidinone chitosan, a gel-forming resorbable biopolymer obtained from crab chitosan by chemical modification. Methylpyrrolidinone chitosan promoted osteoconduction and the space left after avulsion was filled with newly formed bone tissue, which conferred desirable mechanical and physiological characteristics to the healed would site. Morphological evidence obtained from biopsies confirmed the radiographic data. Methylpyrrolidinone chitosan was progressively depolymerized by lysozyme and was no longer detected 6 months after surgery. None of the 10 patients reported adverse effects over one year of observation.

[Ultrastructural and immunoelectron microscopic study of the desmoplastic stroma in carcinoma of the breast]

Different collagen types (I, III, IV, V) were identified in breast carcinoma desmoplastic tissue by ultrastructural analysis and immunoelectronmicroscopy. Type V collagen is present as a 12 nm. fibril in the stroma, either adjacent to the basement membrane or concentrated around the thicker fibers. Myofibroblasts, fibroblasts and tumor cells can be its major producers. Its possible function as a bridge between different collagens can be utilized, with different finality, by the same cells that have produced it. Furthermore, type V collagen can be involved in tumor invasion of the stroma and in all directional movements of tumor cells, as already demonstrated for other extracellular matrix components.

An ultrastructural analysis of chick embryonic skin development in vitro

Behaviour of 6-day chick embryo thigh skin in vitro in two different nutrients was studied electron microscopically. In explants supported with chicken serum containing medium epithelium keratinized faster than and in a similar way to that in ovo, except for the absence of corpuscola cribriformia in pericytes. It did not in explants supported with chick embryo extract containing medium, but underwent a noticeable ultrastructural evolution, mainly of granular reticulum and Golgi complexes. In the two series of cultures mesenchyme presented the same ultrastructural characteristics, especially as far as collagen fibers were concerned. The above data rule out the suggested regulatory role of collagen fibers in epidermal differentiation and support a possible epidermal two-step differentiative process. They are discussed in relation to the general mechanisms implicated in skin evolution.