bluuebunny/crossref_metadata_2025 huggingface dataset:
Formation and localization of internal polymer columnar structures in liquid crystal cells
Authors: Wang Qingbing , Chien L.-C. , Kumar Satyendra
Published: October 2003

Internal polymer columnar structures in liquid crystal (LC) cells have been produced using the method of thermally-induced phase separation of LC/prepolymer solution and solidified by photopolymerization. These polymer columns adhere to both substrates and enhance control of the LC cell spacing and mechanical stability. The existence and profile of the polymer columns were investigated by optical and scanning electron microscopy techniques. Supertwisted nematic LC cells with polymer columnar structures have been constructed using this method and their electro-optical characteristics measured.
Enhanced light diffraction from a double-layer microsphere lattice
Authors: Miyazaki Hideki T. , Miyazaki Hiroshi , Shinya Norio , Miyano Kenjiro
Published: October 2003

Anomalously strong diffraction, whose efficiency is as high as 55%, has been observed from a double-layer microsphere lattice. The enhancement is due to the specular resonance scattering from two spheres in contact, each belonging to the top and bottom layers of the double-layer, respectively. The system thus works as a single layer two-dimensional (2D) lattice of bispheres. No enhancement is observed from a single-layer lattice nor from triple-layer lattice. It functions as a “blazed” transmission grating with 2D spectral dispersion compared with the one-dimensional dispersion in ordinary linear gratings.
Nanoscale pseudoelastic behavior of indented titanium–nickel films
Authors: Ma X.-G. , Komvopoulos K.
Published: October 2003

The pseudoelastic behavior of shape memory alloy (SMA) materials is a phenomenon associated with reversible thermoelastic martensitic transformation. Despite significant insight into macroscopic pseudoelasticity, relatively little is known about the mechanisms responsible for the pseudoelastic behavior at nanometer scales. Recent demands for powerful microdevices and high-density data storage have motivated SMA film studies. In this study, nanoindentation experiments were performed with sputtered austenite titanium–nickel (TiNi) films using a surface force microscope equipped with an acoustic emission sensor. Results reveal the occurrence of pseudoelasticity at the nanoscale and the significance of normal load, nanoindenter tip radius, and partial unloading on the transition from pseudoelastic to elastic-plastic deformation of the TiNi films. The mechanisms associated with the reversible phase transformation and the energy dissipated in TiNi films exhibiting pseudoelasticity are interpreted in the context of nanoindentation results. The findings of this work demonstrate the high potential of TiNi films in high-density storage and microactuator applications.
Ferromagnetism in Mn-doped CuO
Authors: Yang S. G. , Li T. , Gu B. X. , Du Y. W. , Sung H. Y. , Hung S. T. , Wong C. Y. , Pakhomov A. B.
Published: October 2003

Ferromagnetic properties have been observed in CuO doped with 3.5–15 at. % of Mn. The transition from ferromagnetic to paramagnetic phase at TC=80 K is associated with the metal–insulator transition. Magnetoresistance is weakly negative in the vicinity of the transition, but positive in a wide range of temperatures below TC. The experimental results suggest a possibility of interpretation in terms of the Zener double-exchange mechanism and strong electron–phonon interactions.
Conducting-tip atomic force microscopy for injection and probing of localized charges in silicon nanocrystals
Authors: Banerjee Souri , Salem Mohamed Ali , Oda Shunri
Published: October 2003

A conducting-tip atomic force microscopy (AFM) is utilized to inject localized charges in an ensemble of closely packed nanocrystalline Si dots prepared by plasma decomposition of SiH4. A noncontact-mode topography imaging carried out to probe the charging effect indicates an increase in the apparent height of the Si nanocrystal. A generalized tip-sample force interaction model is also developed to quantitatively evaluate the deposited charge. The study prescribes that the presence of surface charges might result in an overestimation of the actual height of an object measured by AFM, which could be nontrivial for a nanomaterial in particular.
Metastability of two-hydrogen complexes in silicon
Authors: Chadi D. J.
Published: October 2003

A two-hydrogen interstitial complex (H2**) in crystalline Si that exhibits metastability is proposed via first-principles total energy calculations. In its most stable state, H2** is 0.28 eV/H higher in energy than H2* and is electron-spin-resonance inactive. The complex has a metastable spin active state arising from a Si dangling-bond in which the H–H separation is 2.39 Å. The properties of H2** make it a promising candidate for the defect responsible for the Staebler–Wronski effect in amorphous Si.
Field-effect experiments in NdBa2Cu3O7−δ ultrathin films using a SrTiO3 single-crystal gate insulator
Authors: Matthey D. , Gariglio S. , Triscone J.-M.
Published: October 2003

We report on the electrostatic modulation of superconductivity in very thin films of cuprate superconductors using a field-effect device based on a SrTiO3 single-crystal gate insulator. A Tc modulation of 3.5 K and a 37% change of the normal state resistance have been observed in an epitaxial bilayer composed of an insulating PrBa2Cu3O7−δ layer deposited on top of a superconducting NdBa2Cu3O7−δ film, two unit cells thick. To achieve large electric fields, the thickness of the commercial dielectric single-crystal SrTiO3 substrate (also used as the gate insulator) was reduced to 110 μm. The dielectric properties of the gate insulator were characterized as a function of temperature and electric field and the magnitude of the field effect was quantified. A Tc enhancement of 2.8 K was obtained for an applied field of −1.8×106 V/m, corresponding to a polarization of −4 μC/cm2.
Light-induced defect states in hydrogenated amorphous silicon centered around 1.0 and 1.2 eV from the conduction band edge
Authors: Pearce J. M. , Deng J. , Collins R. W. , Wronski C. R.
Published: October 2003

To take into account the presence of multiple light-induced defect states in hydrogenated amorphous silicon (a-Si:H) the evolution of the entire spectra of photoconductive subgap absorption, α(hν), has been analyzed. Using this approach two distinctly different light-induced defect states centered around 1.0 and 1.2 eV from the conduction band edge are clearly identified. Results are presented on their evolution and respective effects on carrier recombination that clearly point to the importance of these states in evaluating the stability of different a-Si:H solar cell materials, as well as elucidating the origin of the Staebler–Wronski effect.
Magnetization reversal under nonuniform magnetic fields at conditions relevant to magnetic random access memory applications
Authors: Kim K. S. , Lee C. E. , Lim S. H.
Published: October 2003

Magnetization reversal behavior is examined under various nonuniform fields, the conditions of which are relevant to magnetic random access memory applications. During the magnetization reversal, the end domains play a key role at a uniform field, but they play a negligible role at a nonuniform field. Instead, a ripple pattern is initially formed in the interior and it progresses to form a vortex, resulting in a reversed domain. The switching field is found to be greater in the case of a nonuniform field, but, under a bias field, it is reduced greatly to a level similar to that for a uniform field. This result may indicate a wide window for the bit selectivity under a nonuniform field in magnetic random access memory applications.
Scanning tunneling microscope mediated nanostructure fabrication from GeH4 on Si(111)-(7×7)
Authors: Schöffel U. R. , Rauscher H. , Behm R. J.
Published: October 2003

The tungsten tip of a scanning tunneling microscope, covered with GeHx by exposure to GeH4, was used to locally grow nanometer-sized Ge or GeHx islands on a Si(111)-(7×7) surface. This was achieved by transfer of material from the tip to the surface, induced by voltage pulses. A model, based on the diffusion of adsorbates on the tip and desorption stimulated by an electric field, is presented to account for the results.
Field emission from zinc oxide nanopins
Authors: Xu C. X. , Sun X. W.
Published: October 2003

Nanostructural zinc oxide pins have been fabricated by vapor transport on copper-coated silicon wafer. The nanopins are composed of hexagonal wurtzite-phase zinc oxide with single crystal quality. The growth process includes two steps: (1) growth of a micron-sized zinc oxide dot on the substrate and (2) growth of a sharp tip from the zinc oxide dot. The field emission of the nanopins shows a low field emission threshold (1.92 V/μm at a current density of 0.1 μA/cm−2) and high current density with a field enhancement factor of 657. The emission current density and the electric field follow Fowler–Nordheim relationship. The good performance for field emission is attributed to the single-crystalline structure and the nanopin geometry.
Uniformity of optical absorption in HgCdTe epilayer measured by infrared spectromicroscopy
Authors: Phillips J. D. , Moazzami K. , Kim J. , Edwall D. D. , Lee D. L. , Arias J. M.
Published: October 2003

Infrared absorption in HgCdTe epitaxial material has been investigated using infrared spectromicroscopy to study the uniformity at dimensions representative of typical infrared detectors. Infrared transmission measurements were performed on HgCdTe material using an infrared beam diameter of 9 μm. Line scans and area maps of transmission spectra were obtained to investigate statistical variations in infrared absorption. The HgCdTe material demonstrates a high degree of uniformity, with a standard deviation in absorption coefficient near the sensitive turn-on region of less than 3% and standard deviation in extracted Hg1-xCdxTe compositon of 3×10−4.
Solid-liquid phase transitions in CdTe crystals under pulsed laser irradiation
Authors: Gnatyuk V. A. , Aoki T. , Gorodnychenko O. S. , Hatanaka Y.
Published: October 2003

Phase transitions in CdTe crystals irradiated with nanosecond KrF (248 nm) excimer laser pulses were investigated by a numerical simulation and time-resolved reflectivity method. By solving the time-dependent heat flow equation and taking into account the temperature dependences of semiconductor parameters, the time dependence of the surface temperature in a CdTe crystal was calculated as a function of laser pulse intensity. The dynamics of laser-induced melting was directly monitored by measurements of the reflection coefficient of a probe laser beam (532 nm). The melting and ablation thresholds have been determined as 2.5 and 7.3 MW/cm2, respectively.
Influence of dimensionality on the emission spectra of nanostructures
Authors: Apalkov V. M. , Chakraborty Tapash
Published: October 2003

We report on our results of the numerical simulations of a quantum dot (quantum wire)-quantum well cascade structure. Experimental work on the quantum dot structure was recently reported in the literature. For parameters of such a structure, the calculated emission spectra has a single peak for up to four electrons in the dot. The width of the emission line is found to be due to long-range in-plane disorder, resulting mainly due to fluctuations of the height of the dots.
Building quality housing services
Authors: Croal Gerard , Ogden Susan M. , Grigg Nigel P.
Published: October 2003

Repair and maintenance play a key role in housing management and tenant satisfaction. In the UK, local authority housing departments have traditionally had these services carried out in‐house by local authority building services departments. For more than a decade, such departments have been under pressure to improve their efficiency and effectiveness from public policy initiatives such as compulsory competitive tendering and, more recently, best value. Within some authorities the transfer of housing stock from local authority control to housing associations with non‐profit‐making status is also adding to pressure for quality improvement by raising tenant expectations. Presents a case study of a total quality management initiative implemented within a local authority in Scotland facing precisely these pressures. The success of the quality improvement programme is examined, comparing the perceptions of the tenants and employees with key performance indicators. The pressures to succeed are high since, following an initial five‐year period of grace, the contract for the delivery of building services will only be renewed if the newly‐appointed housing association is satisfied with the efficiency and effectiveness of services delivered. The findings highlight the importance of managing the quality chain across organisational boundaries.
Prepayment of mortgage borrowers having a Bauspar‐Loan
Authors: Cieleback Marcus
Published: October 2003

In the USA, a substantial literature has emerged to investigate the prepayment behaviour of mortgage borrowers, using loan level data to identify the effects of borrower characteristics. This paper supplements the existing literature in three ways. First, the study looks for the first time at the prepayment behaviour of German mortgage borrowers. Second, it uses a unique Bauspar‐Loan data set consisting of over 55,000 Bauspar‐Loans paid off or prepaid between January 1998 and September 2000. Third, based on the special characteristics of the Bauspar‐Loan, it is possible to identify a portfolio optimizing behaviour as the driving force for prepayment.
Games Played by Rogue Proteins in Prion Disorders and Alzheimer's Disease
Authors: Aguzzi Adriano , Haass Christian
Published: October 2003

The incidence of Alzheimer's disease (AD) and that of prion disorders (PrD) could not be more different. One-third of octogenarians succumb to AD, whereas Creutzfeldt-Jakob disease typically affects one individual in a million each year. However, these diseases have many common features impinging on the metabolism of neuronal membrane proteins: the amyloid precursor protein APP in the case of AD, and the cellular prion protein PrP
C
in PrD. APP begets the Aβ peptide, whereas PrP
C
begets the malignant prion protein PrP
Sc
. Both Aβ and PrP
Sc
are associated with disease, but we do not know what triggers their accumulation and neurotoxicity. A great deal has been learned, however, about protein folding, misfolding, and aggregation; an entirely new class of intramembrane proteases has been identified; and unsuspected roles for the immune system have been uncovered. There is reason to expect that prion research will profit from advances in the understanding of AD, and vice versa.
Origin and Migration of the Alpine Iceman
Authors: Müller Wolfgang , Fricke Henry , Halliday Alex N. , McCulloch Malcolm T. , Wartho Jo-Anne
Published: October 2003

The Alpine Iceman provides a unique window into the Neolithic-Copper Age of Europe. We compared the radiogenic (strontium and lead) and stable (oxygen and carbon) isotope composition of the Iceman's teeth and bones, as well as40Ar/39Ar mica ages from his intestine, to local geology and hydrology, and we inferred his habitat and range from childhood to adult life. The Iceman's origin can be restricted to a few valleys within ∼60 kilometers south(east) of the discovery site. His migration during adulthood is indicated by contrasting isotopic compositions of enamel, bones, and intestinal content. This demonstrates that the Alpine valleys of central Europe were permanently inhabited during the terminal Neolithic.
Solution of Poisson's equation for finite systems using plane-wave methods
Authors: Castro A , Rubio A , Stott M J
Published: October 2003

Reciprocal-space methods for solving Poisson's equation for finite charge distributions are investigated. Improvements to previous proposals are presented, and their performance is compared in the context of a real-space density-functional-theory code. Two basic methodologies are followed: calculation of correction terms and imposition of a cutoff to the Coulomb potential. We conclude that these methods can be safely applied to finite or aperiodic systems with a reasonable control of speed and accuracy. PACS Nos.: 2.30.Jr, 71.15.m
Exact time-dependent decoherence factor and its adiabatic classical limit
Authors: Shen J -Q , Chen P , Mao H
Published: October 2003

The present paper finds the complete set of exact solutions of the general time-dependent dynamical models for quantum decoherence, by making use of the LewisRiesenfeld invariant theory and the invariant-related unitary transformation formulation. Based on this, the general explicit expression for the decoherence factor is then obtained and the adiabatic classical limit of an illustrative example is discussed. The result (i.e., the adiabatic classical limit) obtained in this paper is consistent with what is obtained by other authors, and furthermore we obtain more general results concerning time-dependent nonadiabatic quantum decoherence. It is shown that the invariant theory is appropriate for treating both the time-dependent quantum decoherence and the geometric phase factor. PACS Nos.: 03.65.Ge, 03.65.Bz
Singular-value decomposition method in atomic scattering
Authors: Zerrad E , Khan A -S , Zerrad K , Rawitscher G
Published: October 2003

A new numerical method for solving the integro-differential equations that appear in the theory of atomic scattering is devised. It consists of decomposing the kernel into separable terms via the method of singular-value decomposition. A set of integro-differential equations involving the residual integral kernel are then solved to obtain the wave function and from this the phase shift is evaluated. PACS Nos.: 23.23.+x, 56.65.DY
Some remarks on Dirac's hole theory versus quantum field theory
Authors: Solomon D
Published: October 2003

Dirac's hole theory and quantum field theory are generally considered to be equivalent to each other. However, it has been recently shown that this is not necessarily the case. In this article, we will discuss the reason for this lack of equivalence and suggest a possible solution.PACS Nos.: 03.65.w, 11.10.z
Transmission and reflection of a wave packet with a small width in one-dimensional quantum mechanics
Authors: Toyama F M , Nogami Y
Published: October 2003

The transmission and the reflection of a wave incident on a potential in one-dimensional quantum mechanics are usually discussed by assuming that a plane wave eikx or a broad wave packet is incident. We are interested in what happens if the width of the incident wave packet is very small. In this case, the incident wave packet can spread out in such a way that part of the wave packet turns around before reaching the potential area and proceeds backward. This can clearly be visualized by means of the Bohm trajectories associated with the wave packet. We discuss a complication that arises in this case regarding the notion of the reflection probability.PACS Nos.: 03.65w, 03.65.Nk
Gene Transfer Strategies for Correction of Lysosomal Storage Disorders
Authors: d’Azzo Alessandra
Published: October 2003

Lysosomal storage diseases (LSDs) represent a large group of monogenic disorders of metabolism, which affect approximately 1 in 5,000 live births. LSDs result from a single or multiple deficiency of specific lysosomal hydrolases, the enzymes responsible for the luminal catabolization of macromolecular substrates. The consequent accumulation of undigested metabolites in lysosomes leads to polysystemic dysfunction, including progressive neurologic deterioration, mental retardation, visceromegaly, blindness, and early death. In general, the residual amount of functional enzyme in lysosomes determines the severity and age at onset of the clinical symptoms, implying that even modest increases in enzyme activity might affect a cure. A key feature on which therapy for LSDs is based is the ability of soluble enzyme precursors to be secreted by one cell type and reinternalize by neighboring cells via receptor-mediated endocytosis and routed to lysosomes, where they function normally. In principle, somatic gene therapy could be the preferred treatment for LSDs if the patient’s own cells could be genetically modified in vitro or in vivo to constitutively express high levels of the correcting enzyme and become the source of the enzyme in the patient. Both ex vivo and in vivo gene transfer methods have been experimented with for gene therapy of lysosomal disorders. Several of these methods have proved efficient for the transfer of genetic material into deficient cells in culture and reconstitution of enzyme activity. However, the same methods applied to humans or animal models have been giving inconsistent results, the bases of which are not fully understood. A broader knowledge of disease pathogenesis, facilitated by available, faithful animal models of LSDs, coupled to the development of better gene transfer systems as well as the understanding of vector host interactions will make somatic gene therapy for these devastating and complex diseases the most suitable therapeutic approach.
Gene Therapy for Chronic Granulomatous Disease
Authors: Goebel W. Scott , Dinauer Mary C.
Published: October 2003

Identification of gene mutations responsible for leukocyte dysfunction along with the application of gene transfer technology has made genetic correction of such disorders possible. Much of the research into molecular therapy for inherited disorders of phagocytes has been focused on chronic granulomatous disease (CGD). CGD results from mutations in any one of the four genes encoding essential subunits of respiratory burst NADPH oxidase, the enzyme complex required for the production of reactive oxygen intermediates in phagocytes. The absence of phagocyte oxidants results in a predisposition to recurrent bacterial and fungal infections and inflammatory granulomas in CGD patients, associated with significant morbidity and mortality. Allogeneic bone marrow transplantation can cure CGD, but transplant-related toxicity and the limited availability of matched donors have restricted its wider application. Because the gene defects causing CGD are known, and CGD is a stem cell disorder treatable by marrow transplantation, CGD has emerged as a promising disease for somatic gene therapy targeted at the hematopoietic system. Multiple reports have demonstrated the reconstitution of NADPH oxidase activity by gene transfer to human CGD marrow and cell lines cultured in vitro. CGD mouse models have been developed by gene disruption, and preclinical studies on these animals using recombinant retroviral vectors have demonstrated reconstitution of functionally normal neutrophils and increased resistance to pathogens such as Aspergillus fumigatus, Burkholderia cepacia and Staphylococcus aureus. Although the results of these murine studies are encouraging, human phase-I clinical studies in CGD patients have yet to produce clinically beneficial numbers of corrected neutrophils for extended periods. Efforts to improve gene transfer efficiency into human hematopoietic stem cells and to increase engraftment of transduced stem cells are ongoing.
Neurological Toxicity of Ifosfamide
Authors: Nicolao P. , Giometto B.
Published: October 2003

Ifosfamide is an alkylating agent with well-demonstrated efficacy against a large number of malignant diseases. With cyclophosphamide it shares a toxicity profile characterized by myelosuppression and urotoxicity, but ifosfamide has additionally disclosed adverse neurological effects. Ifosfamide-related central nervous system toxicity is characterized by metabolic encephalopathy of varying severity. Symptoms have been reported in 5–30% of all patients treated with ifosfamide. The mechanism of ifosfamide-related central nervous system toxicity has not been fully elucidated, although the symptoms have most often been noted when the drug is given at high doses or administered orally. The neurotoxicity is generally self-limiting and reversible between 48 and 72 h after discontinuation of ifosfamide, although fatal sequelae have been reported. Therapeutic options are now available.
Antiblastic Drug Combinations with Ifosfamide: An Update
Authors: Fulfaro F. , Valerio M.R. , Badalamenti G. , Gebbia N. , Russo A.
Published: October 2003

Ifosfamide is an alkylating agent that is widely used in the treatment of various neoplasms, such as sarcomas, lymphomas, pediatric malignancies, germ cell tumors, lung, breast and ovarian cancer. The clinical toxicity of ifosfamide depends on the dose and administration schedules. The pharmacologic features of this drug enable its combination with other antiblastic agents, such as vinorelbine, gemcitabine, paclitaxel and docetaxel. Moreover, the pharmacologic profile of ifosfamide allows the use of this antiblastic drug in patients who have previously failed many other treatments, and a large percentage of responses has already been obtained. There is some concern about the optimal scheduling of the drug with other novel chemotherapeutics. Clinical trials that include pharmacokinetic and pharmacodynamic studies may be the most efficient way to optimize the therapeutic efficacy of ifosfamide and define the dosing and scheduling.
Ifosfamide in Advanced/Disseminated Breast Cancer
Authors: Sorio R. , Lombardi D. , Spazzapan S. , La Mura N. , Tabaro G. , Veronesi A.
Published: October 2003

Ifosfamide is an alkylating agent active in various tumor types including breast cancer. The availability of mesna (sodium 2-mercaptoethanesulfonate) has increased its safety, avoiding the main dose-limiting side effect, urotoxicity. Interesting activity as a single agent, with response rates ranging from 7 to 30%, is reported in pretreated patients; more attractive data derived from phase II studies on ifosfamide combined with drugs known to be active in advanced breast cancer show response rates always over 35%. This review has taken in consideration papers published after 1995 and available on PubMed medline: the data indicate a potential usefulness of ifosfamide in the clinical management of advanced breast cancer, even if the exact therapeutic role of the drug in this setting should be derived from randomized studies not yet available.
Linomide and Antibody-Targeted Superantigen Therapy Abolishes Formation of Liver Metastases in Mice
Authors: Liu Q. , Klintman D. , Corbascio M. , Ekberg H. , Hedlund G. , Forsberg G. , Thorlacius H.
Published: October 2003

Hematogenous spread of tumor cells and metastasis formation in the liver are insidious aspects of cancer progression and are not frequently amenable to curative treatment. We examined the effect of Linomide and antibody-targeted therapy against the formation of hepatic metastases in vivo. For this purpose, syngenic B16 melanoma cells transfected with GA733-2 (a human colon cancer cell surface antigen) were injected into a mesenteric vein of C57/Bl6 mice. To test bacterial superantigen (Sag) targeting for immunotherapy of liver metastases, we used genetically fused proteins consisting of SEA and a Fab moiety of a GA733-2 tumor-reactive antibody (C215Fab-SEA). Linomide dose-dependently reduced hepatic metastases, and at 300 mg/kg this reduction was more than 80%. Treatment with C215Fab-SEA decreased metastases formation by 49% and the combination of Linomide and C215Fab-SEA was found to completely abolish liver metastases (>99% reduction). Taken together, our novel data suggest that Linomide and antibody-targeted superantigen therapy individually markedly reduce and together abolish liver metastases. Considering that current therapy of hepatic metastases is mainly limited to surgical resection in a subgroup of patients, these findings indicate that Linomide alone or in combination with antibody-targeted superantigen may provide a novel approach against liver metastases.
Serum and Drainage Fluid Vascular Endothelial Growth Factor Levels in Early Surgical Wounds
Authors: Karayiannakis A.J. , Zbar A. , Polychronidis A. , Simopoulos C.
Published: October 2003

Background: Wound healing relies on a coordinated expression and release of growth factors controlling angiogenesis. We measured vascular endothelial growth factor (VEGF) levels in serum and early wound fluid following primary sutured and mesh repair of abdominal hernias. Materials and Methods: Thirty-seven patients were studied measuring serum and wound drainage fluid VEGF by enzyme-linked immunosorbent assay preoperatively and on the 1st, 3rd, 5th and 7th postoperative days. Results: Serum and wound fluid VEGF levels increased significantly by the 3rd postoperative day and continued to rise during the conduct of the study with wound fluid concentrations always exceeding serum levels. The kinetics of VEGF increases were similar in both types of hernia repair; however, serum and wound levels rose slightly earlier in the mesh repair group. Conclusions: Steadily increasing levels of VEGF are detected during the early proliferative phase of wound healing in both serum and wound fluid. It is unknown whether either is predictive for delayed hernia recurrence.
Dual Control by Regulators, GntH and GntR, of the GntII Genes for Gluconate Metabolism in Escherichia coli
Authors: Tsunedomi Ryouichi , Izu Hanae , Kawai Takuya , Yamada Mamoru
Published: October 2003

Escherichia coli possesses two systems, GntI and GntII, for gluconate uptake and catabolism, whose genes are regulated by GntR as a repressor and GntH as an activator, respectively. Additionally, GntH exerts negative control of the GntI genes via the same binding element as that of GntR. We thus examined whether GntR involves regulation of the GntII genes or not. This regulation and the control by GntH were examined by using single-copy lacZ operon fusions and by RT-PCR, suggesting positive and negative regulation by GntR and positive regulation by GntH. Moreover, the introduction of mutations into possible GntR-binding elements revealed that both regulators share at least one of the elements. The results presented allow us to speculate that GntR initiates expression of the GntII genes, followed by their large induction by GntH when cells were grown in gluconate minimum medium. As in the case of the GntI genes, such a cross-regulation between the GntI and GntII via the two regulators may be important for cells to grow with gluconate.
Relationship between Resistance to Erythropoietin and High Anomalous Hemoglobin Levels in Hemodialysis Patients with Beta-Thalassemia Minor
Authors: Di Iorio Biagio , Guastaferro Pasquale , Bellizzi Vincenzo
Published: October 2003

In dialysis patients β-thalassemia is a cause of resistance to erythropoietin (EPO). The aim of the present study is to evaluate the relationship between the amount of circulating anomalous hemoglobin chain and EPO resistance in hemodialysis. Ten hemodialyzed patients with β-thalassemia minor were studied. The mean hemoglobin level was 9.22 ± 0.91 g/dl, the HbA2 ranging between 5.6 and 6.8%; the weekly EPO dose was 13,500 ± 7,185 IU/week and significantly correlated with HbA2 (r = 0.965; p = 0.0001). When stratifying patients in two groups according to HbA2 level (LOW <6%, n = 4; HIGH >6%, n = 6; HbA2 levels, respectively, 5.7 ± 0.1 and 6.4 ± 0.3 g/dl, p = 0.002), it was evidenced that the need of EPO was 13,200 ± 3,033 IU/week in LOW and 36,167 ± 13,060 IU/week in HIGH (p < 0.001). The EPO Resistance Index in the two groups was 13.4 ± 4.1 IU/kg BW/week/g Hb in LOW and 21.9 ± 10.0 in HIGH (p < 0.05). No differences were evidenced between the two groups regarding age, dialysis, body weight, serum levels of urea nitrogen, creatinine, albumin, C-reactive protein, aluminum, ferritin, transferrin and parathyroid hormone. In conclusion, in patients with β-thalassemia minor on chronic hemodialysis, the amount of anomalous hemoglobin chain directly correlate with EPO dose, strongly indicating the magnitude of resistance to erythropoietin.
Effect of Local Physical Training on the Forearm Arteries and Veins in Patients with End-Stage Renal Disease
Authors: Rus Rina R. , Ponikvar Rafael , Kenda Rajko B. , Buturović-Ponikvar Jadranka
Published: October 2003

Aim: We investigate the effects of local training on the forearm vessels in patients with end-stage renal disease. Methods: Fourteen hemodialysis patients were included. Handgrip training was performed for 8 weeks. The following parameters were measured at the beginning of the study and 4 and 8 weeks later: forearm circumference, maximal handgrip strength, and artery and vein parameters, including endothelium-dependent and endothelium-independent vasodilatation (using ultrasound and duplex Doppler scanning). Results: The maximal handgrip strength increased significantly. The radial artery diameters were significantly higher after 8 weeks of training. The endothelium-dependent vasodilatation was found to be significantly increased after 4 and 8 weeks of training. The maximal vein diameters increased significantly with training, with preserved distensibility. Conclusions: The present study suggests that regular handgrip training increases the diameters of forearm vessels. It also improves endothelium-dependent vasodilatation. These changes point to the possible beneficial effects of daily handgrip training in chronic renal failure patients before arteriovenous fistula construction.
Three-Month Treatment Course of Methylphenidate Increases Plasma Levels of Dehydroepiandrosterone (DHEA) and Dehydroepiandrosterone-Sulfate (DHEA-S) in Attention Deficit Hyperactivity Disorder
Authors: Maayan Rachel , Yoran-Hegesh Roni , Strous Rael , Nechmad Allon , Averbuch Elena , Weizman Abraham , Spivak Baruch
Published: October 2003

Methylphenidate is considered by many to be the treatment of choice for attention deficit hyperactivity disorder (ADHD). Methylphenidate exerts its therapeutic effects through the dopaminergic, serotonergic and noradrenergic systems, however its effects on other neurophysiological systems, such as the neurosteroidal system, remain unknown. Dehydroepiandrosterone (DHEA) and its sulfate ester (DHEA-S) are neuroactive steroids with effects on several neurophysiological and behavioral processes. The purpose of the present study was to determine the effect of 3 months of treatment with methylphenidate on circulatory DHEA, DHEA-S, and cortisol in children with ADHD. The study population consisted of 15 boys (aged 11.5 ± 1.6 years) with ADHD, combined type. Subjects were evaluated before and after methylphenidate treatment with a specific rating scale for the assessment of inattention and impulsivity in ADHD. Results show that treatment led to significant clinical improvement in all subjects. Furthermore, following 3 months of treatment, there was a significant increase in serum levels of DHEA and DHEA-S but not in circulatory levels of cortisol. The mean rate of increase in DHEA levels was 23 and 53.6% in DHEA-S. Our findings suggest that DHEA and DHEA-S may play a role in the therapeutic effects of methylphenidate. Several mechanisms to explain this action are proposed, including involvement of the serotonergic, GABA-ergic and noradrenergic pathways.
Temporomesial Activation in Young Females Associated with Unpleasant Words concerning Body Image
Authors: Shirao Naoko , Okamoto Yasumasa , Okada Go , Okamoto Yuri , Yamawaki Shigeto
Published: October 2003

Previous behavioral studies suggest that people who have an abnormal eating behavior may perceive information concerning body image distortion more aversively than others. We performed a functional magnetic resonance imaging (fMRI) study on 15 young women, using an emotional decision task including unpleasant words concerning body image and neutral words. The left amygdala and right parahippocampal gyrus were activated by unpleasant words concerning body image relative to neutral words. In addition, activation of the right parahippocampal gyrus was negatively correlated with the severity of psychological and behavioral problems assessed by the Eating Disorder Inventory-2. This activation also positively correlated with the subjects’ rating of pleasantness of words concerning body image. These results demonstrated that the temporomesial area plays an important role in the perception of unpleasant words concerning body image. In particular, it is suggested that the right parahippocampal gyrus may be associated with subjective sensitivity to unpleasant information concerning body image.
Pretreatment Interhemispheric EEG Coherence Is Related to Seizure Duration in Right Unilateral Electroconvulsive Therapy
Authors: Adler Georg , Hey Wolfgang , Achenbach Caroline , Kinzer Andreas
Published: October 2003

Objective: The relationships between pretreatment EEG parameters and seizure duration in electroconvulsive therapy (ECT) were studied in order to provide information useful for the prediction of ECT-induced seizures. Methods: In 16 depressed patients treated with right unilateral ECT, pretreatment absolute band powers and interhemispheric coherences were assessed and correlated with the duration of the first ECT-induced seizure. Results: Interhemispheric coherence for the central electrodes in the fast alpha band was positively correlated with seizure duration. Conclusions: Interhemispheric coherence may reflect, in a quantitative manner, cortico-cortical transmission via commissural pathways required for the generation of a generalized seizure through right unilateral stimulation. It may represent a useful parameter with respect to seizure threshold with potential therapeutic implications for ECT.
Erythropoietin Protects against Necrotizing Enterocolitis of Newborn Rats by the Inhibiting Nitric Oxide Formation
Authors: Kumral Abdullah , Baskın Hüseyin , Duman Nuray , Yilmaz Osman , Tatli Mansur , Özer Erdener , Gökmen Necati , Genc Sermin , Özkan Hasan
Published: October 2003

Background: Necrotizing enterocolitis (NEC) is an important neonatal disease with a high mortality rate; erythropoietin (Epo) is a hematopoietic growth factor. Functional Epo receptors are in the fetal and postnatal small bowel and their ligands are available for binding. Excessive nitric oxide (NO) production by an isoform of NO synthase inducible by inflammatory stimuli leads to changes in vascular permeability and tissue injury. The aim of this study was to investigate NO formation in an experimental model of NEC and the possible role of NO in the protection Epo provides against NEC. Methods: Twenty-four Wistar albino rat pups were divided into three groups: group 1 = control; group 2 = hypoxia-reoxygenation and saline; group 3 = hypoxia-reoxygenation and recombinant human EPO (rhEpo) pretreatment. rhEpo was given 750 U/kg/week by intraperitoneal injection 3 times a week for 2 weeks. On the 15th day, hypoxia was induced by placing the pups in a 100% CO2 chamber for 5 min. After the hypoxia period the pups were reoxygenated for 10 min with 100% O2 and returned to their mothers. All pups were killed 4 h after the hypoxia-reoxygenation period was over. The abdomen was opened and representative samples of injured areas were taken for histopathologic examination. Then nitrite levels were determined in the intestine by Griess Reagent. Results: On histopathological examination, injury scores in group-2 animals were found to be significantly higher than in group-3 animals (p = 0.001). Significantly increased intestinal nitrite levels were found in group-2 rats compared to the rats of groups 1 and 3 (p = 0.001 and p = 0.001, respectively). There was a positive correlation between the histological findings and the intestinal nitrite levels in group-2 and -3 animals (r = 0.94, p = 0.001; r = 0.99, p = 0.001, respectively). Conclusion: The present study demonstrates that the Epo-pretreated group had decreased levels of NO and limited mucosal necrosis in intestinal tissue samples. We believe that these results deserve further experimental studies in order to elucidate the possible effector mechanisms involved in the inhibitory relationship between Epo, NO and NEC.
Can Growth Hormone (GH) Accelerate Aging? Evidence from GH-Transgenic Mice
Authors: Bartke Andrzej
Published: October 2003

Overexpression of heterologous growth hormone (GH) in transgenic mice results in numerous phenotypic effects, including a drastically shortened life span. Early onset of pathological changes in the kidneys, glomerulosclerosis and glomerulonephritis, undoubtedly contributes to and perhaps accounts for reduced longevity of these animals. However, GH-transgenic mice exhibit various symptoms of accelerated aging, including increased astrogliosis, shortened reproductive life span, and early onset of age-related changes in cognitive function, hypothalamic neurotransmitter turnover, and plasma corticosterone levels. The hypothesis that supraphysiological levels of GH can accelerate aging derives indirect support from findings in GH-deficient and GH-resistant mutant mice in which aging is delayed and the life-span is increased and from the reciprocal relationship of body size and longevity within species.
Neonatal Estrogen Decreases Neural Density of the Septum–Midbrain Central Gray Connection Underlying the Lordosis-Inhibiting System in Female Rats
Authors: Tsukahara Shinji , Ezawa Naoki , Yamanouchi Korehito
Published: October 2003

Neurons in the lateral septum (LS) with projecting axons to the midbrain central gray (MCG) exert an inhibitory influence on lordosis. The number of such neurons is greater in female than in male rats. In this experiment, effects of neonatal estrogen on the density of the LS-MCG connections and on lordosis behavior were examined in female rats. On postnatal day 4 (day 0 = day of birth), females were injected subcutaneously with 50 or 100 µg estradiol benzoate (EB) or oil. On postnatal day 60, females and control males were gonadectomized. Behavioral tests were carried out after the implantation of silicone tubes containing estradiol. Lordotic activities in both males and EB-treated females were lower than in oil-treated females. After completing the behavioral tests, the animals were injected with Fluoro-Gold (FG), a retrograde tracer, into the right-side MCG and the number of FG-labeled neurons in the LS was measured. In all groups, the right-side LS ipsilateral to the FG injection had more FG-labeled neurons than the left-side LS. The number of FG-labeled neurons in the LS of oil-treated females was larger than that of males on both right and left sides. In the females treated with 100 µg EB (EB100), the number of FG-labeled neurons was comparable with that of males and lower than that of oil-treated females. The number of FG-labeled neurons in the EB50 females was also lower than that in oil-treated females, but tended to be larger than that observed in the EB100 group. These results indicate that neonatal estrogen decreases both lordotic activity and the density of the LS-MCG neural connections in female rats.
The Significance of Trace Proteinuria
Authors: Sam R. , Shaykh M.S. , Pegoraro A.A. , Khalili V. , Hristea I. , Singh A.K. , Arruda J.A.L. , Dunea G.
Published: October 2003

Background: The clinical significance of a trace protein reading on urinalysis is unclear, and such a result is often ignored by the clinician. Methods: We examined 185 samples of urine with trace proteinuria by both Chemstrips and sulfosalicylic acid testing, and compared the results with those of urinary albumin and total protein concentrations. Results: Taking for the purposes of this study an arbitrary upper limit of normal of 20 mg/l for albumin and 100 mg/l for total protein concentration, we found abnormal albumin excretion in 87% and abnormal total protein excretion in 88% of trace samples. In this study, a negative urinalysis for protein excluded microalbuminuria in 87% and proteinuria in 78% of cases. Conclusion: Qualitative testing for protein by urinalysis has a high sensitivity and specificity for diagnosing or ruling out microalbuminuria. Trace proteinuria usually means microalbuminuria; negative proteinuria tends to rule it out.
Induction of Cytokines and Adhesion Molecules in Stable Hemodialysis Patients: Is There an Effect of Membrane Material?
Authors: Hoffmann Ute , Fischereder Michael , Marx Manfred , Schweda Frank , Lang Bernhard , Straub Rainer H. , Krämer Bernhard K.
Published: October 2003

Background/Aims: The aim of this study was to examine the effects of a biocompatible and a nonbiocompatible hemodialysis membrane on the secretion of cytokines and their specific antagonists as well as on the expression of adhesion molecules. Methods: A crossover study using cuprophane (CU) and polysulfone (PS) dialyzers and measurements of serum tumor necrosis factor (TNF)-alpha, soluble TNF receptors, interleukin (IL)-6, IL-6 receptor, IL-2 receptor, IL-1 receptor antagonist and the adhesion molecules intercellular adhesion molecule 1, endothelial leukocyte adhesion molecule and vascular cell adhesion molecule was performed in 19 hemodialysis patients. 44 healthy volunteers served as controls. Results: All of the measured cytokines and cytokine antagonists as well as all adhesion molecules were significantly elevated in hemodialysis patients compared to controls. There was a significant increase in TNF-alpha during a dialysis session with a CU dialyzer, but only a moderate increase using a PS dialyzer. None of the other cytokines and adhesion molecules were changed during a dialysis session. We were also able to show an upregulation of adhesion molecules in dialysis patients. Conclusion: Our study clearly demonstrates that levels of inflammatory cytokines as well as their antagonists and adhesion molecules are elevated in patients on hemodialysis therapy. Baseline values before the start of a dialysis session did not show any differences with regard to the usage of CU or PS dialysis membranes. However, CU dialyzers led to a significantly greater stimulation of TNF-alpha during the dialysis session in comparison to PS membranes, suggesting a higher degree of bioincompatibility.
Respiratory failure in chronic obstructive pulmonary disease
Authors: Calverley P.M.A.
Published: October 2003

Respiratory failure is still an important complication of chronic obstructive pulmonary disease (COPD) and hospitalisation with an acute episode being a poor prognostic marker. However, other comorbid conditions, especially cardiovascular disease, are equally powerful predictors of mortality.

The physiological basis of acute respiratory failure in COPD is now clear. Significant ventilation/perfusion mismatching with a relative increase in the physiological dead space leads to hypercapnia and hence acidosis. This is largely the result of a shift to a rapid shallow breathing pattern and a rise in the dead space/tidal volume ratio of each breath. This breathing pattern results from adaptive physiological responses which lessen the risk of respiratory muscle fatigue and minimise breathlessness.

Treatment is directed at reducing the mechanical load applied to each breath, correcting specific precipitating factors,e.g.bacterial infection, and maintaining gas exchange. Both bronchodilators and oral corticosteroids can improve spirometric results in exacerbations of COPD and should be routinely offered to patients with respiratory failure. Controlled oxygen is still not always prescribed appropriately and high inspired oxygen concentrations can lead to severe acidosis by either worsening ventilation/perfusion mismatching and/or inducing a degree of hypoventilation. Ventilatory support using noninvasive ventilation has revolutionised the approach to these patients.

Acute respiratory failure due to chronic obstructive pulmonary disease remains a common medical emergency that can be effectively managed. More attention should be focused on the prevention of these episodes and identifying the factors which cause early relapse.