High-temperature superconductivity at the lanthanum cuprate/lanthanum-strontium nickelate interface.

The utilization of interface effects in epitaxial systems at the nanoscale has emerged as a very powerful approach for engineering functional properties of oxides. Here we present a novel structure fabricated by a state-of-the-art oxide molecular beam epitaxy method and consisting of lanthanum cuprate and strontium (Sr)-doped lanthanum nickelate, in which interfacial high-temperature superconductivity (Tc up to 40 K) occurs at the contact between the two phases. In such a system, we are able to tune the superconducting properties simply by changing the structural parameters. By employing electron spectroscopy and microscopy combined with dedicated conductivity measurements, we show that decoupling occurs between the electronic charge carrier and the cation (Sr) concentration profiles at the interface and that a hole accumulation layer forms, which dictates the resulting superconducting properties. Such effects are rationalized in the light of a generalized space-charge theory for oxide systems that takes account of both ionic and electronic redistribution effects.

GLUT2 proteins and PPARγ transcripts levels are increased in liver of ovariectomized rats: reversal effects of resistance training.

PURPOSE: This study investigated the effects of ovariectomy (Ovx) and 12 weeks of resistance training (RT) on gene expression of GLUT2, the main glucose transporter in the liver, and on PPARγ, a transcription factor known to target GLUT2 expression. METHODS: Forty Holtzman rats were divided into 5 groups: Sham-sedentary (Sed), Sham- RT, Ovx-Sed, Ovx-RT, and Ovx-Sed with hormone replacement (E2). The RT protocol consisted of sessions held every 72 h for 12 weeks, during which the animals performed 4 to 9 vertical climbs (1.1 m) at 2 min intervals with progressively heavier weights (30 g after the fourth climb) tied to the tail. The E2 silastic capsule was inserted into the rats' backs 48 hours before the first RT session. RESULTS: In addition to liver fat, GLUT2 protein levels and PPARγ transcripts were increased (P < 0.05) in Ovx compared to Sham-Sed animals, suggesting increased hepatic glucose uptake under estrogen deficient conditions. RT and E2 in Ovx rats decreased liver fat accumulation as well as GLUT2 and PPARγ gene expression to the level of Sham- Sed animals. CONCLUSION: The results of this study suggest that liver GLUT2 as well as PPARγ expression in Ovx rats are accompanied by increased fat accumulation and glucose uptake, thus providing a substrate for increased de novo lipogenesis. RT appears to be an appropriate exercise model to circumvent these effects.

High-temperature superconductivity in space-charge regions of lanthanum cuprate induced by two-dimensional doping.

The exploitation of interface effects turned out to be a powerful tool for generating exciting material properties. Such properties include magnetism, electronic and ionic transport and even superconductivity. Here, instead of using conventional homogeneous doping to enhance the hole concentration in lanthanum cuprate and achieve superconductivity, we replace single LaO planes with SrO dopant planes using atomic-layer-by-layer molecular beam epitaxy (two-dimensional doping). Electron spectroscopy and microscopy, conductivity measurements and zinc tomography reveal such negatively charged interfaces to induce layer-dependent superconductivity (Tc up to 35 K) in the space-charge zone at the side of the planes facing the substrate, where the strontium (Sr) profile is abrupt. Owing to the growth conditions, the other side exhibits instead a Sr redistribution resulting in superconductivity due to conventional doping. The present study represents a successful example of two-dimensional doping of superconducting oxide systems and demonstrates its power in this field.

Tunable Charge and Spin Order in PrNiO_{3} Thin Films and Superlattices.

We use polarized Raman scattering to probe lattice vibrations and charge ordering in 12 nm thick, epitaxially strained PrNiO_{3} films, and in superlattices of PrNiO_{3} with the band insulator PrAlO_{3}. A carefully adjusted confocal geometry is used to eliminate the substrate contribution to the Raman spectra. In films and superlattices under tensile strain which undergo a metal-insulator transition upon cooling, the Raman spectra reveal phonon modes characteristic of charge ordering. These anomalous phonons do not appear in compressively strained films, which remain metallic at all temperatures. For superlattices under compressive strain, the Raman spectra show no evidence of anomalous phonons indicative of charge ordering, while complementary resonant x-ray scattering experiments reveal antiferromagnetic order associated with a modest increase in resistivity upon cooling. This confirms theoretical predictions of a spin density wave phase driven by spatial confinement of the conduction electrons.

Orbital control of noncollinear magnetic order in nickel oxide heterostructures.

We have used resonant x-ray diffraction to develop a detailed description of antiferromagnetic ordering in epitaxial superlattices based on two-unit-cell thick layers of the strongly correlated metal LaNiO3. We also report reference experiments on thin films of PrNiO3 and NdNiO3. The resulting data indicate a spiral state whose polarization plane can be controlled by adjusting the Ni d-orbital occupation via two independent mechanisms: epitaxial strain and spatial confinement of the valence electrons. The data are discussed in light of recent theoretical predictions.

Dimensionality control of electronic phase transitions in nickel-oxide superlattices.

The competition between collective quantum phases in materials with strongly correlated electrons depends sensitively on the dimensionality of the electron system, which is difficult to control by standard solid-state chemistry. We have fabricated superlattices of the paramagnetic metal lanthanum nickelate (LaNiO(3)) and the wide-gap insulator lanthanum aluminate (LaAlO(3)) with atomically precise layer sequences. We used optical ellipsometry and low-energy muon spin rotation to show that superlattices with LaNiO(3) as thin as two unit cells undergo a sequence of collective metal-insulator and antiferromagnetic transitions as a function of decreasing temperature, whereas samples with thicker LaNiO(3) layers remain metallic and paramagnetic at all temperatures. Metal-oxide superlattices thus allow control of the dimensionality and collective phase behavior of correlated-electron systems.

Giant superconductivity-induced modulation of the ferromagnetic magnetization in a cuprate-manganite superlattice.

Artificial multilayers offer unique opportunities for combining materials with antagonistic orders such as superconductivity and ferromagnetism and thus to realize novel quantum states. In particular, oxide multilayers enable the utilization of the high superconducting transition temperature of the cuprates and the versatile magnetic properties of the colossal-magnetoresistance manganites. However, apart from exploratory work, the in-depth investigation of their unusual properties has only just begun. Here we present neutron reflectometry measurements of a [Y(0.6)Pr(0.4)Ba(2)Cu(3)O(7) (10 nm)/La(2/3)Ca(1/3)MnO(3) (10 nm)](10) superlattice, which reveal a surprisingly large superconductivity-induced modulation of the vertical ferromagnetic magnetization profile. Most surprisingly, this modulation seems to involve the density rather than the orientation of the magnetization and is highly susceptible to the strain, which is transmitted from the SrTiO(3) substrate. We outline a possible explanation of this unusual superconductivity-induced phenomenon in terms of a phase separation between ferromagnetic and non-ferromagnetic nanodomains in the La(2/3)Ca(1/3)MnO(3) layers.

Orbital reconstruction and covalent bonding at an oxide interface.

Orbital reconstructions and covalent bonding must be considered as important factors in the rational design of oxide heterostructures with engineered physical properties. We have investigated the interface between high-temperature superconducting (Y,Ca)Ba(2)Cu3O7 and metallic La(0.67)Ca(0.33)MnO3 by resonant x-ray spectroscopy. A charge of about -0.2 electron is transferred from Mn to Cu ions across the interface and induces a major reconstruction of the orbital occupation and orbital symmetry in the interfacial CuO2 layers. In particular, the Cu d(3z(2)-r(2)) orbital, which is fully occupied and electronically inactive in the bulk, is partially occupied at the interface. Supported by exact-diagonalization calculations, these data indicate the formation of a strong chemical bond between Cu and Mn atoms across the interface. Orbital reconstructions and associated covalent bonding are thus important factors in determining the physical properties of oxide heterostructures.

[Preliminary experiences on triscaphoid arthrodesis]. / Prime esperienze sull'artrodesi triscafoidea.

The authors report their experience of 5 patients (4 males, 1 female) with a mean age of 36.4 years (min 25 years, max 45 years), undergoing triscaphoid arthrodesis between May 1989 and August 1993. The patients suffered from rotatory dislocation of the scaphoid (1 case) and stage 3A of Kienboeck's disease according to Lichtman's classification (4 cases). The paper describes the surgical technique used for partial arthrodesis of the wrist performed using plexual anesthesia. A dorsal access route is used through a curved longitudinal skin incision corresponding to the anatomical site of the scaphoid. The skin flaps are then peeled back revealing the surface veins and sensitive branches of the radial nerve which are isolated and conserved. Having cut through the retinaculum of the extensors, the extensor tendons are spread so as to reach the joint capsule which is sectioned crosswise. After the bone to be fused have been exposed, the cartilage is removed from the joint faces between the scaphoid, trapezium and trapezoid and, using a osteotribe, the subchondral bone is removed to reveal the spongy bone, leaving a space of approximately 6 mm between the spongy surface of the bones to be fused. Arthodesis is stabilised using Kirschner wires or metal minicambres enclosing scaphoid, trapezium and trapezoid. Spongy tissue is taken from the distal radial head and used as a graft to fill the spaces created between them which will consolidate over time. The wrist is immobilised in a plaster cast for 8 weeks before starting functional rehabilitation. Patients were checked both clinically and radiographically with a mean follow-up of 36.4 months (min 25, max 50 months). Using the assessment criteria proposed by Minami et al. excellent results were obtained in 4 patients (80%) with the disappearance of painful symptoms, joint excursion 50% greater than the normal wrist, and hand grip 70% greater than in the controlateral hand. There was good radiographical consolidation of the arthrodesis. Poor results were only recorded in one case (20%) with persisting pain and functional impotent. Radio-scaphoid arthrosis was observed radiographically consequent to hypercorrection of the scaphoid with a radio-scaphoid angle of less than 45 degrees. The authors underline the technical difficulty of this arthrodesis characterised by reduction of the scaphoid in a correct position in which the radio-scaphoid angle must be 45 degrees when measured from a lateral position. Lastly, the authors conclude that this from of arthrodesis may be used with good results to treat wrist pathologies such as rotatory scaphoid dislocation, triscaphoid arthrosis and Kien-boeck's disease at stage 3A according to Lichtman. They also affirm that arthrodesis limited to the wrist is preferable to total arthrodesis because it enables some joint movement to be conserved which is important for hand function.

Partial arthrodeses of the wrist.

The authors report 16 cases of partial arthrodeses of the wrist for the treatment of Kienboeck's disease, pseudarthrosis of the scaphoid, rotatory subluxation of the scaphoid, rheumatoid arthritis, etc. Based on the good results obtained (76.6%) the authors believe that partial arthrodeses constitute the type of treatment indicated for the treatment of pathologies that involve only some of the carpal bones, and they also emphasize that this type of surgery represents a valid alternative to total arthrodesis of the wrist.

Replantation and revascularization of large segments of the hand and forearm.

From November 1985 to July 1989, the authors performed replantation or revascularization surgery on 18 patients in whom a large segment of the upper limb between the elbow and the palm of the hand had been either completely severed (9 cases) or incompletely severed with ischemia (9 cases). The operation was successful in 16 cases, and the authors were able to clinically review 14 patients (average follow-up, 23 months). The results were analyzed using a protocol based on the following parameters: range of motion, sensation, muscle strength, cold intolerance, pain, return to work, cosmesis, and the patient's level of satisfaction. The final outcome was rated excellent in 2 cases, good in 6 cases, fair in 3 cases, and poor in 3 cases. The authors point out that recovery of sensory and motor function in replantation of large portions of the hand and forearm is often difficult. Nevertheless, the good cosmetic result, the lack of pain, and the high probability of returning to work made the patients quite satisfied with this kind of reconstructive surgery.

Hemangioma of the hand.

The authors describe the anatomopathological and clinical findings of 24 cases of benign hemangioma of the hand. The instrumental methods used to diagnose hemangioma are discussed, and MRI imaging is given particular importance in the preoperative evaluation of the site, size, extent, and relationship with the surrounding tissues and any multiple locations of the vascular tumor. This evaluation is essential to perform a wide resection of the tumor, which is the only means of avoiding recurrence. After an average follow-up of 33 months (14-54) recurrence was observed in 7% of the cases treated.

Epidemiological and structural findings supporting the fibromatous origin of dorsal knuckle pads.

Epidemiological, optical and electron microscopical findings suggest that dorsal knuckle pads and Dupuytren's disease are fibrosing disorders with common features. In all cases examined, knuckle pads were always associated with Dupuytren's contracture and, in a significant number of cases, with bilateral Dupuytren's contracture. In a statistically significant number of patients with knuckle pads, Ledderhose's and Peyronie's diseases were also present (P less than 0.001). Optical and electron microscopical studies showed that cell types and extracellular matrix were identical in knuckle pads and Dupuytren's nodules in different patients.

High testosterone levels of ovarian origin affect adrenal steroidogenesis?

Androgens of ovarian origin have been suggested to affect adrenal enzymatic activity. To investigate this possibility, the 17-hydroxyprogesterone (17-OH P) and cortisol (F) responses to an ACTH stimulation test (0.25 mg iv, bolus) were evaluated in 10 normal women and in 39 hyperandrogenic women with normal (14 subjects) or high (25 subjects) testosterone (T) levels. The 17-OH P release and the ratio between 17-OH P and F release in response to the ACTH stimulation test were significantly higher (P less than 0.05) in hyperandrogenic women with high T levels than in normal subjects. Eight hyperandrogenic women with high T received intranasal GnRH agonist (Buserelin, 1200 micrograms/day) for 4 weeks, and the 17-OH P and F release in response to the ACTH stimulation was reassessed after agonist treatment. At the end of GnRH agonist administration the mean circulating levels of T were significantly reduced (P less than 0.05). The F response to the ACTH test was not modified by pretreatment with the GnRH agonist. The 17-OH P response to the ACTH stimulation test after the GnRH agonist was unchanged in comparison with control tests, as well as the ratio between 17-OH P and F responses to the ACTH test. These data do not seem to confirm, as previously suggested, that high T levels of ovarian origin affect adrenal steroidogenesis.

Evaluation of ischaemic necrosis of carpal bones by magnetic resonance imaging.

Nine patients with chronic pain in the wrist were examined by M.R.I. to evaluate its accuracy in the detection of ischaemic necrosis of carpal bones. In seven patients, M.R.I. confirmed scintigraphic and radiographic signs of ischaemic necrosis. In two patients with radionuclide accumulations, M.R.I. did not confirm the diagnosis: in one, M.R.I. was totally normal and in the other it showed signs of a healing scaphoid fracture. From this limited experience, M.R.I. seems to be a sensitive imaging modality which is more specific than scintigraphy.

Transfer in emergencies of the left ring finger to the right thumb. Case report.

The authors report a case of serious crushing of both hands treated in emergency situation with transfer of the left ring finger, which could not be replanted, to the right thumb, as well as revascularization of the four fingers of the right hand.

Carpal tunnel syndrome in Madelung's deformity.

The authors describe a case of carpal tunnel syndrome due to Madelung's deformity. They discuss the pathophysiological causes of median nerve entrapment to explain the compression which occurs in this disease and its clinical implications. They take also into consideration the surgical approach to the carpal tunnel in this particular condition.