bluuebunny/crossref_metadata_2025 huggingface dataset:
COVARIANT ENERGY IN MECHANICS
Authors: CARINI M. , FATIBENE L. , FRANCAVIGLIA M.
Published: September 2007

Different notions of mechanical energy and conservation laws are considered and discussed from the viewpoint of transformation laws with respect to changes of reference.

Here, in particular, we shall consider and investigate the behavior of suitable conservation laws in non-inertial frames.
GEOMETRIC ALGEBRAS AND EXTENSORS
Authors: FERNÁNDEZ V. V. , MOYA A. M. , RODRIGUES W. A.
Published: September 2007

This is the first paper in a series (of four) designed to show how to use geometric algebras of multivectors and extensors to a novel presentation of some topics of differential geometry which are important for a deeper understanding of geometrical theories of the gravitational field. In this first paper we introduce the key algebraic tools for the development of our program, namely the euclidean geometrical algebra of multivectors [Formula: see text] and the theory of its deformations leading to metric geometric algebras [Formula: see text] and some special types of extensors. Those tools permit obtaining, the remarkable golden formula relating calculations in [Formula: see text] with easier ones in [Formula: see text] (e.g. a noticeable relation between the Hodge star operators associated to G and GE). Several useful examples are worked in details for the purpose of transmitting the "tricks of the trade".
MULTIVECTOR AND EXTENSOR FIELDS ON SMOOTH MANIFOLDS
Authors: MOYA A. M. , FERNÁNDEZ V. V. , RODRIGUES W. A.
Published: September 2007

The main objective of this paper (second in a series of four) is to show how the Clifford and extensor algebras methods introduced in a previous paper of the series are indeed powerful tools for performing sophisticated calculations appearing in the study of the differential geometry of a n-dimensional manifold M of arbitrary topology, supporting a metric field g (of given signature (p,q)) and an arbitrary connection ∇. Specifically, we deal here with the theory of multivector and extensor fields on M. Our approach does not suffer the problems of earlier attempts which are restricted to vector manifolds. It is based on the existence of canonical algebraic structures over the canonical (vector) space associated to a local chart (Uo, ϕo) of a given atlas of M. The key concepts of a-directional ordinary derivatives of multivector and extensor fields are defined and their properties studied. Also, we recall the Lie algebra of smooth vector fields in our formalism, the concept of Hestenes derivatives and present some illustrative applications.
"MINIMAL GEOMETRIC DATA" APPROACH TO DIRAC ALGEBRA, SPINOR GROUPS AND FIELD THEORIES
Authors: CANARUTTO DANIEL
Published: September 2007

The first three sections contain an updated, not-so-short account of a partly original approach to spinor geometry and field theories introduced by Jadczyk and myself [3–5]; it is based on an intrinsic treatment of 2-spinor geometry in which the needed background structures do not need to be assumed, but rather arise naturally from a unique geometric datum: a vector bundle with complex 2-dimensional fibers over a real 4-dimensional manifold. The following two sections deal with Dirac algebra and 4-spinor groups in terms of two spinors, showing various aspects of spinor geometry from a different perspective. The last section examines particle momenta in 2-spinor terms and the bundle structure of 4-spinor space over momentum space.
NONLINEAR REALIZATION OF THE LOCAL CONFORM-AFFINE SYMMETRY GROUP FOR GRAVITY IN THE COMPOSITE FIBER BUNDLE FORMALISM
Authors: ALI S. A. , CAPOZZIELLO S.
Published: September 2007

A gauge theory of gravity based on a nonlinear realization (NLR) of the local Conform-Affine (CA) group of symmetry transformations is presented. The coframe fields and gauge connections of the theory are obtained. The tetrads and Lorentz group metric are used to induce a spacetime metric. The inhomogenously transforming (under the Lorentz group) connection coefficients serve as gravitational gauge potentials used to define covariant derivatives accommodating minimal coupling of matter and gauge fields. On the other hand, the tensor valued connection forms serve as auxiliary dynamical fields associated with the dilation, special conformal and deformational (shear) degrees of freedom inherent in the bundle manifold. The bundle curvature of the theory is determined. Boundary topological invariants are constructed. They serve as a prototype (source free) gravitational Lagrangian. The Bianchi identities, covariant field equations and gauge currents are obtained.
KINETIC RESISTANCE OF CARBON FULLERENES IN AQUEOUS SOLUTION
Authors: SHEN HAIJUN
Published: September 2007

This article has been retracted at the request of the Editors. It is fully identical with another article Kinetic resistance of carbon fullerenes in aqueous solution which was published in Computers and Applied Chemistry Vol. 24 No. 6 (June 2007) 819-822. It is inappropriate and violates the scientific rule of anti-plagiarism. We regret that this was not detected before the article was accepted for publication in the journal.
ENHANCEMENT OF NANO-RC SWITCHING DELAY DUE TO THE RESISTANCE BLOW-UP IN InGaAs
Authors: TAN MICHAEL L. P. , SAAD ISMAIL , ISMAIL RAZALI , ARORA VIJAY K.
Published: September 2007

RC and transit-time delays in a nanocircuit, where the resistor is a few nanometers in length, are evaluated taking into account the velocity and current saturation and applied to RC switching delay in InGaAs heterojunction field effect transistor (HFET). Transit time delay is the dominant factor in the ohmic regime where the applied voltage V is less than the critical voltage Vc for the onset of nonlinear nonohmic behavior. However, RC time constant is predominant in the nonohmic regime and increases linearly with the applied step voltage. The power in the nanocircuit is smaller and rises linearly in the nonohmic regime as compared to the quadratic behavior in the ohmic regime.
EVOLUTION OF STRUCTURE OF LIQUID AND AMORPHOUS Al2O3·2SiO2 NANOPARTICLES UPON COOLING FROM THE MELTS
Authors: LINH NGUYEN NGOC , HOANG VO VAN
Published: September 2007

Structural properties of liquid and amorphous Al 2 O 3·2 SiO 2 nanoparticles have been investigated by molecular dynamics (MD) method. The simulations were done in a spherical model with different sizes of 2 nm, 3 nm and 4 nm under nonperiodic boundary conditions. We use the Born–Mayer type interatomic potentials. We determined the changes in mean interatomic distances, coordination number distributions, partial radial distribution functions (PRDFs) and bond-angle distributions of Al 2 O 3·2 SiO 2 nanoparticles upon cooling towards glassy state. Calculations show that liquid and amorphous Al 2 O 3·2 SiO 2 nanoparticles have a slightly distorted tetrahedral network structure with the mean coordination number Z Al - O ≈ 4.0 and Z Si - O ≈ 4.0, which is contrary to that of the liquid and amorphous bulk. Temperature dependence of structural defects in nanoparticles was found and discussed. In addition, we found size effects on glass transition temperature of Al 2 O 3·2 SiO 2 nanoparticles in that it decreases with decreasing size.
EXTRACTION OF METALLIC NANOTUBES OF ZEOLITE-SUPPORTED SINGLE-WALLED CARBON NANOTUBES SYNTHESIZED FROM ALCOHOL
Authors: MAEDA YUTAKA , HASHIMOTO MASAHIRO , HASEGAWA TADASHI , KANDA MAKOTO , TSUCHIYA TAKAHIRO , WAKAHARA TAKATSUGU , AKASAKA TAKESHI , MIYAUCHI YUHEI , MARUYAMA SHIGEO , LU JING , NAGASE SHIGERU
Published: September 2007

Single-walled carbon nanotubes (SWNTs) synthesized by catalytic decomposition of an alcohol were purified by extraction. The purified SWNTs were characterized on the basis of visible-near infrared (vis-NIR) absorption, photoluminescence and Raman spectroscopic analyses, scanning electron microscopy (SEM) observation, and thermal analysis. Selective extraction of metallic nanotubes was also achieved by the extraction condition.
PRESSURE-ASSISTED SPINNING: A UNIQUE AND VERSATILE APPROACH FOR DIRECTLY FABRICATING MEMBRANES WITH MICRO- AND NANOFIBERS
Authors: ARUMUGANATHAR SUMATHY , JAYASINGHE SUWAN N.
Published: September 2007

Fibers are structurally interesting components most useful in a range of applications spanning the physical and life science areas of research. These membrane (scaffold) forming fibers have been explored in applications ranging from microfilteration to advanced biological investigations in tissue engineering to controlled and targeted drug delivery. One such robust fiber generation approach investigated for over a century, which has recently been exploited, is the well-established threading process referred to as electrospinning. In this technique, single- or multi-phase media are charged within a conducting needle and later exposed to an electric field which promotes the formation of a continuous micro- to nanosized fiber(s) which over a period of collection time has been reported for forming scaffolds and membranes. This process has been explored for a wide range of polymer composite-based materials and the technique has now reached the point where it has moved into industrial production. We report here as a first example a comparable fiber to membrane fabrication approach completely driven by the coupling of a coaxial needle system with a pressure. We refer to this novel methodology as pressure-assisted spinning (PAS) where the hazardous element of high voltage (as in the case of electrospinning) is nonexistent. Hence, our discovery introduces both a directly competing fiber, scaffold to membrane fabrication approach, which is versatile and has no associated hazards as those in electrospinning. Furthermore as our technique is nonelectric field driven, the media spun into fibers could have a high electrical conductivity, which in this case has no effect on the stability in processing near-uniform fibers/scaffolds to membranes. The fabricated fibers and membranes generated by means of this approach could directly be used for a plethora of applications spanning the engineering and biological areas of research.
ZnO-BASED NANOWIRES
Authors: PEARTON S. J. , KANG B. S. , TIEN L. C. , NORTON D. P. , HEO Y. W. , REN F.
Published: September 2007

ZnO has properties well-suited to UV/visible light emitters, transparent thin film electronics and a variety of gas and chemical sensor applications. There has been extensive interest in recent times in synthesis of ZnO nanowires by a number of methods using both catalyst and catalyst-free approaches. In this paper we review our recent results on developing functional nanowires in the ZnMgO systems and show some applications in hydrogen gas sensing, pH sensing, transparent transistors and UV detectors. In terms of sensors, the main selling points are large surface-to-volume ratio for improved detection sensitivity and also low power requirements.
MICROBE-MEDIATED NANOTRANSFORMATION: CADMIUM
Authors: JHA ANAL K. , PRASAD K. , KULKARNI A. R.
Published: September 2007

An eco-friendly microbe (lactobacillus sp.)-mediated synthesis of cadmium nanoparticles is reported. The synthesis is performed at room temperature. X-ray and transmission electron microscopy analyses are performed to ascertain the formation of Cd nanoparticles. Individual nanoparticles as well as a number of aggregates almost spherical in shape having a size of 40–60 nm are found.
Hide-and-Seek: The Challenge of Viral Persistence in HIV-1 Infection
Authors: Geeraert Luc , Kraus Günter , Pomerantz Roger J.
Published: September 2007

The success of highly active antiretroviral therapy (HAART) for HIV-1 infection has sparked interest in mechanisms by which the virus can persist despite effectively suppressive therapy. Latent HIV-1 reservoirs established early during infection not only prevent sterilizing immunity but also represent a major obstacle to virus eradication. When HIV-1 gains a foothold in the immunologic memory or in certain inaccessible compartments of the human body, it cannot be easily purged by HAART and is able to replenish systemic infection on treatment interruption. Because latently infected cells are indistinguishable from uninfected cells, deliberate activation of latent infection combined with intensified HAART seems to be the best strategy to combat latent infection. Initial hypothesis-driven clinical trials did not achieve their ultimate goal, although they provided valuable insight for the design of future eradication protocols. A more detailed understanding of the basic mechanisms underlying the establishment and long-term maintenance of HIV-1 reservoirs will be critical in developing new eradication approaches.
Therapy of Marfan Syndrome
Authors: Judge Daniel P. , Dietz Harry C.
Published: September 2007

Marfan syndrome is a common inherited disorder of connective tissue caused by deficiency of the matrix protein fibrillin-1. Effective surgical therapy for the most life-threatening manifestation, aortic root aneurysm, has led to a nearly normal lifespan for affected individuals who are appropriately recognized and treated. Traditional medical therapies, such as beta-adrenergic receptor blockade, are used to slow pathologic aortic growth and decrease the risk of aortic dissection by decreasing hemodynamic stress. New insights regarding the pathogenesis of Marfan syndrome have developed from investigation of murine models of this disorder. Fibrillin-1 deficiency is associated with excess signaling by transforming growth factor beta (TGFβ). TGFβ antagonists have shown great success in improving or preventing several manifestations of Marfan syndrome in these mice, including aortic aneurysm. These results highlight the potential for development of targeted therapies based on discovery of disease genes and interrogation of pathogenesis in murine models.
Activation of G Protein–Coupled Receptors: Beyond Two-State Models and Tertiary Conformational Changes
Authors: Park Paul S.-H. , Lodowski David T. , Palczewski Krzysztof
Published: September 2007

Transformation of G protein–coupled receptors (GPCRs) from a quiescent to an active state initiates signal transduction. All GPCRs share a common architecture comprising seven transmembrane-spanning α-helices, which accommodates signal propagation from a diverse repertoire of external stimuli across biological membranes to a heterotrimeric G protein. Signal propagation through the transmembrane helices likely involves mechanistic features common to all GPCRs. The structure of the light receptor rhodopsin may serve as a prototype for the transmembrane architecture of GPCRs. Early biochemical, biophysical, and pharmacological studies led to the conceptualization of receptor activation based on the context of two-state equilibrium models and conformational changes in protein structure. More recent studies indicate a need to move beyond these classical paradigms and to consider additional aspects of the molecular character of GPCRs, such as the oligomerization and dynamics of the receptor.
Adaptation to altitude as a vehicle for experiential learning of physiology by university undergraduates
Authors: Weigle David S. , Buben Amelia , Burke Caitlin C. , Carroll Nels D. , Cook Brett M. , Davis Benjamin S. , Dubowitz Gerald , Fisher Rian E. , Freeman Timothy C. , Gibbons Stephen M. , Hansen Hale A. , Heys Kimberly A. , Hopkins Brittany , Jordan Brittany L. , McElwain Katherine L. , Powell Frank L. , Reinhart Katherine E. , Robbins Charles D. , Summers Cameron C. , Walker Jennifer D. , Weber Steven S. , Weinheimer Caroline J.
Published: September 2007

In this article, an experiential learning activity is described in which 19 university undergraduates made experimental observations on each other to explore physiological adaptations to high altitude. Following 2 wk of didactic sessions and baseline data collection at sea level, the group ascended to a research station at 12,500-ft elevation. Here, teams of three to four students measured the maximal rate of oxygen uptake, cognitive function, hand and foot volume changes, reticulocyte count and hematocrit, urinary pH and 24-h urine volume, athletic performance, and nocturnal blood oxygen saturation. Their data allowed the students to quantify the effect of altitude on the oxygen cascade and to demonstrate the following altitude-related changes: 1) impaired performance on selected cognitive function tests, 2) mild peripheral edema, 3) rapid reticulocytosis, 4) urinary alkalinization and diuresis, 5) impaired aerobic but not anaerobic exercise performance, 6) inverse relationship between blood oxygen saturation and resting heart rate, and 7) regular periodic nocturnal oxygen desaturation events accompanied by heart rate accelerations. The students learned and applied basic statistical techniques to analyze their data, and each team summarized its results in the format of a scientific paper. The students were uniformly enthusiastic about the use of self-directed experimentation to explore the physiology of altitude adaptation and felt that they learned more from this course format than a control group of students felt that they learned from a physiology course taught by the same instructor in the standard classroom/laboratory format.
Fibroblast growth factor-2 in hyperplastic pituitaries of D2R knockout female mice
Authors: Cristina Carolina , Díaz-Torga Graciela , Góngora Adrián , Guida Maria Clara , Perez-Millán Maria Inés , Baldi Alberto , Becu-Villalobos Damasia
Published: September 2007

Dopamine D2 receptor (D2R) knockout (KO) female mice develop chronic hyperprolactinemia and pituitary hyperplasia. Our objective was to study the expression of the mitogen fibroblast growth factor (FGF2) and its receptor, FGFR1, comparatively in pituitaries from KO and wild-type (WT) female mice. We also evaluated FGF2 subcellular localization and FGF2 effects on pituitary function. FGF2-induced prolactin release showed a similar response pattern in both genotypes, even though basal and FGF2-stimulated release was higher in KO. FGF2 stimulated pituitary cellular proliferation (MTS assay and [3H]thymidine incorporation), with no differences between genotypes. FGF2 concentration (measured by ELISA) in whole pituitaries or cultured cells was lower in KO ( P < 0.00001 and 0.00014). Immunofluorescence histochemistry showed less FGF2 in pituitaries from KO females and revealed a distinct FGF2 localization pattern between genotypes, being predominantly nuclear in KO and cytosolic in WT pituitaries. Finally, FGF2 could not be detected in the conditioned media from pituitary cultures of both genotypes. FGFR1 levels (Western blot and immunohistochemistry) were higher in pituitaries of KO. Basal concentration of phosphorylated ERKs was lower in KO cells ( P = 0.018). However, when stimulated with FGF2, a significantly higher increment of ERK phosphorylation was evidenced in KO cells ( P ≤ 0.02). We conclude that disruption of the D2R caused an overall decrease in pituitary FGF2 levels, with an increased distribution in the nucleus, and increased FGFR1 levels. These results are important in the search for reliable prognostic indicators for patients with pituitary dopamine-resistant prolactinomas, which will make tumor-specific therapy possible.
Distinct roles for intrinsic osteocyte abnormalities and systemic factors in regulation of FGF23 and bone mineralization in Hyp mice
Authors: Liu Shiguang , Tang Wen , Zhou Jianping , Vierthaler Luke , Quarles L. Darryl
Published: September 2007

X-linked hypophosphatemia (XLH) is characterized by hypophosphatemia and impaired mineralization caused by mutations of the PHEX endopeptidase (phosphate-regulating gene with homologies to endopeptidases on the X chromosome), which leads to the overproduction of the phosphaturic fibroblast growth factor 23 (FGF23) in osteocytes. The mechanism whereby PHEX mutations increase FGF23 expression and impair mineralization is uncertain. Either an intrinsic osteocyte abnormality or unidentified PHEX substrates could stimulate FGF23 in XLH. Similarly, impaired mineralization in XLH could result solely from hypophosphatemia or from a concomitant PHEX-dependent intrinsic osteocyte abnormality. To distinguish between these possibilities, we assessed FGF23 expression and mineralization after reciprocal bone cross-transplantations between wild-type (WT) mice and the Hyp mouse model of XLH. We found that increased FGF23 expression in Hyp bone results from a local effect of PHEX deficiency, since FGF23 was increased in Hyp osteocytes before and after explantation into WT mice but was not increased in WT osteocytes after explantation into Hyp mice. WT bone explanted into Hyp mice developed rickets and osteomalacia, but Hyp bone explanted into WT mice displayed persistent osteomalacia and abnormalities in the primary spongiosa, indicating that both phosphate and PHEX independently regulate extracellular matrix mineralization. Unexpectedly, we observed a paradoxical suppression of FGF23 in juvenile Hyp bone explanted into adult Hyp mice, indicating the presence of an age-dependent systemic inhibitor of FGF23. Thus PHEX functions in bone to coordinate bone mineralization and systemic phosphate homeostasis by directly regulating the mineralization process and producing FGF23. In addition, systemic counterregulatory factors that attenuate the upregulation of FGF23 expression in Hyp mouse osteocytes are present in older mice.
On-Demand Therapy Is a Valid Strategy in GERD Patients: Pros and Cons
Authors: Leodolter Andreas , Penagini Roberto
Published: September 2007

On-demand proton pump inhibitor (PPI) therapy is an attractive option for long-term management of gastroesophageal reflux disease (GERD). Controlled trials in non-erosive reflux disease (NERD) patients have shown sufficient symptom control in most patients with a high rate of willingness to continue treatment and substantial saving on PPI expenditure. However, due to the slow onset of action of PPIs, rescue antacids are often used when symptoms recur and several patients continue to experience some degree of heartburn. On-demand treatment is less cost-saving in patients with esophagitis, and symptomatic/endoscopic relapses occur frequently in severe grades. Data on the prevention of long-term sequelae of on-demand treatment are scarce, only indirect evidence being available. It is suggested that PPI continuous maintenance is more appropriate than on-demand therapy in patients with severe esophagitis, in those with Barrett’s esophagus where chronic PPIs may reduce incidence of dysplasia, in uninvestigated elderly patients where esophagitis is more prevalent and it is more frequently complicated with gastrointestinal bleeding and possibly in uninvestigated or NERD patients with frequent clinical relapses. Finally, more appropriate outcome variables should be used in future trials in order to assess efficacy of on-demand treatment adequately.
Multichannel Intraluminal Impedance and pH-Metry for Investigation of Symptomatic Gastroesophageal Reflux Disease
Authors: Weigt J. , Mönkemüller K. , Peitz U. , Malfertheiner P.
Published: September 2007

Background: Combined multichannel intraluminal impedance and pH-metry (MII-pH) is a technique that enables monitoring of gastroesophageal reflux independent of its acidity. Aim: To investigate the utility of MII-pH in the clinical investigation of patients with gastroesophageal reflux disease (GERD) symptoms. Methods: 32 consecutive patients underwent 24-hour ambulatory MII-pH. 16 patients were on PPI (PPI+) therapy and 16 were taking no acid-suppressive medication (PPI–). We investigated the pattern of reflux by means of acid and nonacid reflux and the relation to typical and atypical symptoms. In addition, we investigated the symptom association by using the symptom index. Results: Symptom-related acid reflux was higher in the PPI+ group (33 vs. 25%) and symptom-related nonacid reflux was higher in the PPI– group (36 vs. 21%). The association between type of symptoms and the association to reflux is highly significant (p < 0.001) in the PPI– group. In this group the association of acid reflux is more likely to correlate with typical symptoms and the association of nonacid reflux is more likely to be associated with atypical symptoms. Conclusions: These data show that nonacid reflux can be associated with symptoms in patients with GERD symptoms. The diagnostic value of MII-pH is independent of PPI therapy.
Usefulness of a Serological Panel Test in the Assessment of Gastritis in Symptomatic Children
Authors: De Angelis Gian Luigi , Cavallaro Lucas Giovanni , Maffini Valentina , Moussa Ali Mahamat , Fornaroli Fabiola , Liatopoulou Stefania , Bizzarri Barbara , Merli Roberta , Comparato Giuseppe , Caruana Pietro , Cavestro Giulia Martina , Franzé Angelo , Di Mario Francesco
Published: September 2007

Background: Non-invasive methods are advisable for the detection of Helicobacter pylori-related chronic gastritis in pediatric patients. Serum pepsinogens I and II (sPGII and sPGII), gastrin-17 (G-17) and anti-H. pylori antibodies (IgG-Hp) have been proposed as a ‘serological gastric biopsy’. Aim: To assess H. pylori infection and to evaluate gastric mucosa status in a pediatric population by means of serological parameters such as sPGI, sPGII, G-17 and IgG-Hp. Methods: 45 consecutively children evaluated for upper gastrointestinal symptoms were analyzed. All children were submitted to upper gastrointestinal endoscopy with biopsies. Serum samples were analyzed for IgG-Hp, sPGII, sPGI and G-17 (Biohit, Helsinki, Finland). Results: 18 children had H. pylori-related mild or moderate non-atrophic chronic gastritis. They presented significantly higher mean levels of sPGII and of IgG-Hp than negative ones, eitherunder or up to 10 years. sPGI showed significantly increased levels in H. pylori-positive patients only over 10 years. G-17 levels were not different between H. pylori-positive and -negative ones. The best cut-offs of IgG-Hp, sPGII and of product IgG-Hp·sPGII, to identify H. pylori infection, were 30 IU/l, 9 µg/l, and 241 IU/l·µg/l, respectively. The product IgG-Hp·sPGII identified H. pylori infection with a 100% sensitivity, 92% specificity, 90% positive predictive value and 100% negative predictive value. IgG-Hp and IgG-Hp showed a correlation (r = 0.94; p < 0.001). Conclusions: Combined analysis of sPGII and IgG-Hp antibody levels could be recommended as a non-invasive panel for the assessment of H. pylori-related histological alterations of gastric mucosa in childhood.
Helicobacter pylori and Epigenetic Mechanisms Underlying Gastric Carcinogenesis
Authors: Nardone Gerardo , Compare Debora , De Colibus Patrizia , De Nucci Germana , Rocco Alba
Published: September 2007

Gastric carcinogenesis is a multistep process triggered by Helicobacter pylori and characterized by accumulation of molecular alterations. Two mechanisms are implicated in cancer-related molecular alterations: genetic and epigenetic. The former includes changes in the DNA sequence, the latter occurs without changes of DNA sequence. However, the most important difference between genetic and epigenetic alterations is that epigenetic changes are potentially reversible by eliminating toxic agents. DNA methylation is the major epigenetic phenomenon of eukaryotic genomes and involves the addition of a methyl group to the carbon 5 position of the cytosine ring within the CpG dinucleotide. DNA methylation is needed for the normal development of cells, whereas aberrant methylation of CpG islands confers a selective growth advantage that results in cancerous growth. The stomach is one of the organs frequently showing aberrant methylation of DNA epithelial cells because of its accessibility to exogenous toxic agents such as H. pylori infection. Aberrant methylation of CpG islands occurs early in gastric carcinogenesis, tends to increase as the process advances and is prevalently related to the infection. In conclusion, gastric cancer is mainly an epigenetic disease and H. pylori, acting through inflammatory mediators, may play a key role in the development of such molecular alterations.
Small Intestinal Bacterial Overgrowth: Diagnosis and Treatment
Authors: Gasbarrini Antonio , Lauritano Ernesto Cristiano , Gabrielli Maurizio , Scarpellini Emidio , Lupascu Andrea , Ojetti Veronica , Gasbarrini Giovanni
Published: September 2007

Small intestinal bacterial overgrowth (SIBO) is a clinical condition characterized by a malabsorption syndrome due to an increase in microorganisms within the small intestine. The main mechanisms restricting bacterial colonization in the upper gut are the gastric acid barrier, mucosal and systemic immunity and intestinal clearance. When these mechanisms fail, bacterial overgrowth develops. Diarrhea, steatorrhea, chronic abdominal pain, bloating and flatulence are common symptoms and are similar to those observed in irritable bowel syndrome. Breath tests (glucose and/or lactulose breath tests) have been proposed as a sensitive and simple tool for the diagnosis of bacterial overgrowth, being non-invasive and inexpensive compared to the gold standard represented by the culture of intestinal aspirates. Antibiotic therapy is the cornerstone of SIBO treatment. Current SIBO treatment is based on empirical courses of broad-spectrum antibiotics since few controlled studies concerning the choice and duration of antibiotic therapy are available at present.
Almost All Irritable Bowel Syndromes Are Post-Infectious and Respond to Probiotics: Consensus Issues
Authors: Cuomo Rosario , Savarese Maria Flavia , Gargano Rosalba
Published: September 2007

Several reports have described post-infectious irritable bowel syndrome (Pi-IBS), while many animal and human studies have shown the presence of increased infiltration of inflammatory cells and hyperplasia of enterochromaffin cells in the intestinal mucosa after acute gastroenteritis. The potential value of probiotic bacteria in restoring normal gut function has been demonstrated by animal models of Pi-IBS. In humans, Pi-IBS can be prevented utilizing probiotics to reduce the duration of acute gastroenteritis, despite the variable efficacy shown in randomized control trials evaluating unspecified IBS. Here, advances in the pathophysiology supporting the post-infectious hypothesis are considered. In addition, the current role of probiotics in the management of Pi-IBS is discussed.
Capsule Endoscopy – State of the Art
Authors: De Franchis Roberto , Rondonotti Emanuele , Villa Federica
Published: September 2007

Capsule endoscopy is a new technology that was recently introduced into clinical practice for the diagnosis of gastrointestinal diseases. As of today, three different capsule types have been produced, designed for the exploration of the small bowel (PillCam SB), the esophagus (PillCam ESO) and the colon (PillCam Colon). The PillCam SB has gained widespread acceptance as a powerful tool for the diagnosis of bleeding from the small bowel as well as for other indications. The PillCam ESO has been used to study patients with gastroesophageal reflux disease, for the screening of Barrett’s esophagus, and for the screening and surveillance of esophageal varices in patients with cirrhosis. The results of the pilot studies carried out with this capsule have been encouraging. Large-scale studies are ongoing. The evaluation of the potential of the PillCam Colon capsule is still in its infancy: the two pilot studies published showed that this capsule can produce high-quality images of the colon. The potential of this capsule for clinical purposes, such as colon cancer screening, needs to be evaluated.
Carcinogenesis in Inflammatory Bowel Disease
Authors: Herszenyi Laszlo , Miheller Pal , Tulassay Zsolt
Published: September 2007

Patients with longstanding ulcerative colitis (UC) and Crohn’s disease (CD) have an increased risk of colorectal cancer (CRC). CRC accounts for approximately 15% of all deaths in patients with inflammatory bowel disease (IBD). The molecular pathway leading to CRC in IBD appears to differ from the well-known adenoma-to-CRC sequence, given the fact that these cancers appear to arise from either flat dysplastic tissue or dysplasia-associated lesions or masses. The risk of CRC for patients with IBD increases by 0.5–1% yearly, 8–10 years after diagnosis. Patients with a young age at disease onset, more extensive colitis, greater inflammatory burden, concomitant primary sclerosing cholangitis, and a family history of CRC are at greatest risk. Most cancers arise in pancolitis and there is little or no increased risk associated with proctitis while left-sided colitis carries an intermediate cancer risk. The CRC risk in patients with colonic CD is similar to that of UC. Colonic dysplasia is a precursor to CRC in IBD. There is no clear evidence that surveillance colonoscopy prolongs survival in patients with extensive colitis. Newer endoscopic and molecular techniques are being assessed for their effectiveness in augmenting conventional surveillance.
Population Screening for Colorectal Cancer: Advantages and Drawbacks
Authors: Kronborg Ole , Regula Jaroslaw
Published: September 2007

Screening for colorectal cancer (CRC) has been shown to reduce mortality from the disease as well as incidence. Several methods for screening are available, but none are ideal. The present short review discusses the advantages and drawbacks using fecal occult blood tests (FOBTs), fecal DNA tests, flexible sigmoidoscopy (FS), colonoscopy, double contrast barium enema, and computed tomographic colonoscopy. The use of FOBTs with following colonoscopy in persons with a positive test has been shown to reduce mortality as well as the incidence of CRC in several randomized trials. It is likely that other methods will do the same, but it is not clear how large the benefit will be. Repeated testing is necessary for FOBTs and DNA tests as well as FS, and a high degree of acceptability is crucial for the effectivity of all tests in a national program. National services may be subject to variations in enthusiasm and expertise, resulting in varying acceptability and number of complications. It is recommended to perform pilot studies in limited populations (as in the UK) before embarking on a screening program on a national level.
Management of Hepatocellular Carcinoma
Authors: De Giorgio M. , Fagiuoli S.
Published: September 2007

The aim of this review was to assess the correct clinical management of hepatocellular carcinoma (HCC). Following the diagnosis, the correct choice of treatment must take into account both the anatomical/biological features of HCC and the functional status of the underlying cirrhosis. As of today, only the application of the BCLC scoring system, which stratifies patients according to HCC staging and degree of liver disease in a process leading to a specific treatment, has shown the best results in terms of survival.
A System for the Random Mutagenesis of the Two-Peptide Lantibiotic Lacticin 3147: Analysis of Mutants Producing Reduced Antibacterial Activities
Authors: Field Des , Collins Barry , Cotter Paul D. , Hill Colin , Ross R. Paul
Published: September 2007

Lantibiotics are antimicrobial peptides that contain several unusual amino acids resulting from a series of enzyme-mediated posttranslational modifications. As a consequence of being gene-encoded, the implementation of peptide bioengineering systems has the potential to yield lantibiotic variants with enhanced chemical and physical properties. Here we describe a functional two-plasmid expression system which has been developed to allow random mutagenesis of the two-component lantibiotic, lacticin 3147. One of these plasmids contains a randomly mutated version of the two structural genes, ltnA1 and ltnA2, and the associated promoter, Pbac, while the other encodes the remainder of the proteins required for the biosynthesis of, and immunity to, lacticin 3147. To test this system, a bank of ∼1,500 mutant strains was generated and screened to identify mutations that have a detrimental impact on the bioactivity of lacticin 3147. This strategy established/confirmed the importance of specific residues in the structural peptides and their associated leaders and revealed that a number of alterations which mapped to the –10 or –35 regions of Pbac abolished promoter activity.
Prenatal Cord Clamping in Newborn Macaca nemestrina: A Model of Perinatal Asphyxia
Authors: Juul Sandra E. , Aylward Elizabeth , Richards Todd , McPherson Ronald J. , Kuratani John , Burbacher Thomas M.
Published: September 2007

Our objective was to establish a nonhuman primate model of perinatal asphyxia appropriate for preclinical evaluation of neuroprotective treatment strategies under conditions that closely resemble human neonatal emergencies, and to begin testing the safety and efficacy of erythropoietin neuroprotective treatment. Prior to delivery by hysterotomy, the umbilical cords of near term Macaca nemestrina (n = 8) were clamped for times ranging between 12 and 15 min. Animals received erythropoietin (5,000 U/kg/dose × 2 i.v., n = 3), or vehicle (n = 5) after resuscitation. We assessed physiologic parameters, continuous electroencephalogram, magnetic resonance imaging/spectroscopy, safety parameters and behavior. Animals were euthanized at 4 months of age. Mean birth weight was 507 ± 62 g. Initial arterial pH ranged from 6.75 to 7.12, with base deficits of 17–25 mEq. Animals were flaccid at birth, with attenuated electroencephalograms, and seizures occurred in 3 of 8 animals. We demonstrated magnetic resonance imaging/spectroscopy changes consistent with hypoxia (elevated lactate levels were present in some animals), significant motor and behavioral abnormalities (particularly with 15 min of cord clamping), and evidence of gliosis at the time of death. We have established a reproducible model of moderate to severe perinatal hypoxic-ischemic injury in M. nemestrina newborns. This model, which combines structural, biochemical, and behavioral assessments over time can be used to assess the safety and efficacy of neuroprotective strategies.
Uteroplacental Inflammation Results in Blood Brain Barrier Breakdown, Increased Activated Caspase 3 and Lipid Peroxidation in the Late Gestation Ovine Fetal Cerebellum
Authors: Hutton Lisa C. , Castillo-Melendez Margie , Walker David W.
Published: September 2007

Maternal infection is associated with perinatal brain damage, but effects on the cerebellum are not known in detail. In this study, we examined the effects of placental inflammation induced by administering lipopolysaccharide into the uterine artery of pregnant sheep at 134–136 days gestation. The fetal brain was collected 72 h later and compared to brains collected from age-matched untreated fetuses. Placental lipopolysaccharide treatment had substantial effects on the fetal cerebellum, including increasing the number of cells undergoing apoptosis, widespread lipid peroxidation, and extravasation of plasma albumin, suggesting compromise of the cerebellar blood-brain barrier. These effects may account for some of the learning and motor deficits that emerge in neonates from pregnancies compromised by infection.
Identification of POSH2, a Novel Homologue of the c-Jun N-Terminal Kinase Scaffold Protein POSH
Authors: Wilhelm Michael , Kukekov Nickolay V. , Xu Zhiheng , Greene Lloyd A.
Published: September 2007

The c-Jun N-terminal kinase (JNK) pathway plays an important role in neuronal apoptosis both during normal CNS development and following stroke in adult animals. As with other MAP kinase pathways, scaffold proteins regulate JNK signaling. The scaffold protein POSH (Plenty of SH3s) enhances JNK activation and apoptosis. We identified a POSH homologue, POSH2, which was cloned from rat brain and is present in cortical neurons in vitro. POSH2 mRNA is expressed in a variety of tissues including brain, and this distribution partially overlaps with that of POSH. POSH2 overexpression promotes JNK activation in HEK293 cells and promotes apoptosis in neuronal PC12 cells, which is blocked by a dominant-negative c-Jun. Finally POSH2 contains a functional RING domain and enhances the stability of coexpressed mixed-lineage kinases. These results indicate that POSH2 may regulate JNK activation and consequent apoptosis under conditions of increased expression.
Surgical Implantation of the New FlowSecure™ Artificial Urinary Sphincter in the Female Bladder Neck
Authors: García-Montes Fernando , Vicens-Vicens Antoni , Ozonas-Moragues Mariano , Oleza-Simo Jaime , Mora-Salvá Antonia
Published: September 2007

Objective: To report implantation of the new FlowSecure™ artificial urinary sphincter with conditional occlusion in a female bladder neck, describe surgical technique and suggest minor modifications to accommodate the device for universal female implantation. Patient and Methods: A spina bifida female patient with urodynamically proven stress incontinence due to sphincteric incompetence associated to atonic detrusor was implanted with the new artificial sphincter. Operating time was one and a half hours. The cuff was adjusted to the bladder neck with no problems. Excess belt removed from the cuff was preserved and used for loose fixation of tubing and reservoirs in the right paravesical space. The control pump was placed in the right labia. The prosthesis was implanted at atmospheric pressure zero. Results: The device was easily implanted. There were no perioperative complications. Catheter was removed 24 h post-implantation and patient achieved immediate total continence. There was no need for device pressurization at subsequent follow-up. The patient needed intermittent self-catheterization for emptying her bladder because of impaired detrusor contractility. Conclusions: Despite that the new FlowSecure artificial urinary sphincter has only been used for bulbar urethral implantation, we have successfully implanted the device in a female bladder neck with excellent clinical results. Cuff lengthening and connecting tubes shortening would probably enable all female patients to be suitable for implantation. To the best of our knowledge, this is the first time the device has been implanted in a bladder neck.
Clinical Predictors of Stone Fragmentation Using Slow-Rate Shock Wave Lithotripsy
Authors: Li Wei-Ming , Wu Wen-Jeng , Chou Yii-Her , Liu Chia-Chu , Wang Chii-Jye , Huang Chun-Hsiung , Lee Yung-Chin
Published: September 2007

Aim: To determine efficacy and clinical predictors of stone fragmentation when using slow-rate shock wave lithotripsy (SWL). Patients and Methods: In total, 116 patients with radiopaque urinary tract stones were randomized into two groups: 57 patients were treated with SWL at 90 shocks/min, and 59 patients were treated with SWL at 120 shocks/min. The efficacy of SWL was evaluated within 1 month after treatment. Patient characteristics, features of stones, and SWL conditions were reviewed. Success rates relating to individual parameters were assessed by using chi-square and Student t tests. All factors were further entered into multivariate logistic regression analysis. Results: There were no statistically significant differences between the two groups with regard to age, sex, site and size of the stones, renal function, and total number of shock waves. In univariate analysis, the success rate was significantly related to shock wave frequency (p = 0.023), length and width of the stones (p < 0.001), total number of shock waves (p = 0.047), and age (p = 0.049). In multivariate analysis, however, only shock wave rate and stone length remained statistically significant (p = 0.021 and p = 0.046, respectively). The overall success rate was significantly higher in the group treated with 90 shocks/min (p = 0.02). However, this higher success rate was statistically significant only in patients with a stone length ≧10 mm (50.0 vs. 18.5%, p = 0.019). Conclusion: SWL at 90 shocks/min yielded better outcomes than SWL at 120 shocks/min, particularly in patients with stone lengths ≧10 mm.
Factors Affecting Renal Scar Development in Children with Spina Bifida
Authors: Ozel S.K. , Dokumcu Z. , Akyildiz C. , Avanoglu A. , Ulman I.
Published: September 2007

Background/Aims: Prevention of renal scarring is the main therapeutic goal in children with spina bifida. We aimed to determine factors affecting renal scar development in these patients. Materials and Methods: Records of 312 children admitted between 1994 and 2005 with spina bifida were reviewed. Age on admission, gender, presence of previous febrile urinary tract infections (UTIs), vesicoureteral reflux (VUR), and initial urodynamic findings were noted. Patients were grouped regarding presence/absence of renal scars on DMSA scans. χ2 and Student’s t tests were used for statistical evaluation. Results: Seventy-two patients had renal scars on admission. Mean age was 4.62 ± 4.59 years for patients without renal scars and 6.35 ± 4.9 years for patients with scars. Male/female ratio was 1:1 in the scarless group and 1:2 in the group with scars. Previous febrile UTI was present in 11 of 240 scarless patients in contrast to 7 out of 72 patients in the scar group (p > 0.05). VUR was present in only 16.3% of cases without scars, whereas 36.1% of patients in the scar group had VUR. Detrusor overactivity and detrusor sphincter dyssynergia were observed in 67.1% of scarred patients, whereas this figure was 42.4% in the scarless group. The comparison of age on admission, gender, detrusor overactivity, and detrusor sphincter dyssynergia revealed significant differences between patients with and without renal scars. Conclusions: Late referral, female gender, overactive detrusor, and detrusor sphincter dyssynergia have detrimental effects on renal parenchymal function in spina bifida patients. Patient selection for aggressive treatment using these features may prevent renal parenchymal deterioration.
Laparoscopic Treatment of Simultaneous Tumors in the Liver and Kidney
Authors: Romero Frederico R. , Wagner Andrew A. , Bagga Herman S. , Muntener Michael , Brito Fábio Augusto R. , Kavoussi Louis R.
Published: September 2007

Background/Aims: To report our experience with laparoscopic treatment of liver tumors during right-sided transperitoneal laparoscopic nephrectomy. Methods: Two patients undergoing transperitoneal laparoscopic radical nephrectomy on the right side each had a concomitant tumor in the right lobe of the liver. The first patient was incidentally found to have a lesion suspicious for metastatic disease. The second had a known asymptomatic giant hemangioma of the liver. Results: Total operative time was 130 and 101 min. Estimated blood loss was 400 and 300 ml. There were no complications. The first patient had bilateral papillary renal cell carcinoma and concomitant fibroadipose tissue within the liver. The second patient presented with clear cell carcinoma of the right kidney and a cavernous hemangioma of the liver. Conclusions: When indicated, simultaneous right-sided kidney and liver tumors may be treated by a combined laparoscopic transperitoneal approach. Laparoscopic expertise is advised.
Laparoscopic Management of Patent Urachus in an Adult Man
Authors: Pust Alexandra , Ovenbeck Ralph , Erbersdobler Andreas , Dieckmann Klaus-Peter
Published: September 2007

A 35-year-old man presented with recurrent urinary discharge from the umbilicus. A diagnosis of persistent patent urachus was established by magnetic resonance imaging. Radical excision of urachal remnant tissue was accomplished by laparoscopic surgery using four ports. Magnetic resonance imaging is diagnostic in urachal remnants. Radical excision of urachal remnants may safely be done by laparoscopic access.
Ureteroappendiceal Fistula due to Gossypiboma
Authors: Yaycioglu Ozgur , Ulusan Serife , Ezer Ali , Guvel Sezgin
Published: September 2007

A case of gossypiboma (retained surgical sponge) is described which caused ureteroappendiceal fistula 4 years after an open right ureterolithotomy operation. The patient was treated by removal of the retained sponges, appendectomy and ureteral stent insertion.