bluuebunny/crossref_metadata_2025 huggingface dataset:
Minocycline attenuates microglial activation but fails to mitigate striatal dopaminergic neurotoxicity: role of tumor necrosis factor‐α
Authors: Sriram Krishnan , Miller Diane B. , O'Callaghan James P.
Published: January 2006

Activated microglia are implicated in the pathogenesis of disease‐, trauma‐ and toxicant‐induced damage to the CNS, and strategies to modulate microglial activation are gaining impetus. A novel action of the tetracycline derivative minocycline is the ability to inhibit inflammation and free radical formation, factors that influence microglial activation. Minocycline is therefore being tested as a neuroprotective agent to alleviate CNS damage, although findings so far have yielded mixed results. Here, we showed that administration of a single low dose of 1‐methyl‐4‐phenyl‐1,2,3,6‐tetrahydropyridine (MPTP) or methamphetamine (METH), a paradigm that causes selective degeneration of striatal dopaminergic nerve terminals without affecting the cell body in substantia nigra, increased the expression of mRNAs encoding microglia‐associated factors F4/80, interleukin (IL)‐1α, IL‐6, monocyte chemoattractant protein‐1 (MCP‐1, CCL2) and tumor necrosis factor (TNF)‐α. Minocycline treatment attenuated MPTP‐ or METH‐mediated microglial activation, but failed to afford neuroprotection. Lack of neuroprotection was shown to be due to the inability of minocycline to abolish the induction of TNF‐α and its receptors, thereby failing to modulate TNF signaling. Thus, TNF‐α appeared to be an obligatory component of dopaminergic neurotoxicity. To address this possibility, we examined the effects of MPTP or METH in mice lacking genes encoding IL‐6, CCL2 or TNF receptor (TNFR)1/2. Deficiency of either IL‐6 or CCL2 did not alter MPTP neurotoxicity. However, deficiency of both TNFRs protected against the dopaminergic neurotoxicity of MPTP. Taken together, our findings suggest that attenuation of microglial activation is insufficient to modulate neurotoxicity as transient activation of microglia may suffice to initiate neurodegeneration. These findings support the hypothesis that TNF‐α may play a role in the selective vulnerability of the nigrostriatal pathway associated with dopaminergic neurotoxicity and perhaps Parkinson's disease.
Presenilin clinical mutations can affect γ‐secretase activity by different mechanisms
Authors: Bentahir Mostafa , Nyabi Omar , Verhamme Jan , Tolia Alexandra , Horré Katrien , Wiltfang Jens , Esselmann Hermann , De Strooper Bart
Published: January 2006

Mutations in human presenilin (PS) genes cause aggressive forms of familial Alzheimer's disease. Presenilins are polytopic proteins that harbour the catalytic site of the γ‐secretase complex and cleave many type I transmembrane proteins including β‐amyloid precursor protein (APP), Notch and syndecan 3. Contradictory results have been published concerning whether PS mutations cause ‘abnormal’ gain or (partial) loss of function of γ‐secretase. To avoid the possibility that wild‐type PS confounds the interpretation of the results, we used presenilin‐deficient cells to analyse the effects of different clinical mutations on APP, Notch, syndecan 3 and N‐cadherin substrate processing, and on γ‐secretase complex formation. A loss in APP and Notch substrate processing at ɛ and S3 cleavage sites was observed with all presenilin mutants, whereas APP processing at the γ site was affected in variable ways. PS1‐Δ9 and PS1‐L166P mutations caused a reduction in β‐amyloid peptide (Aβ)40 production whereas PS1‐G384A mutant significantly increased Aβ42. Interestingly PS2, a close homologue of PS1, appeared to be a less efficient producer of Aβ than PS1. Finally, subtle differences in γ‐secretase complex assembly were observed. Overall, our results indicate that the different mutations in PS affect γ‐secretase structure or function in multiple ways.
O6‐methylguanine DNA methyltransferase and p53 status predict temozolomide sensitivity in human malignant glioma cells
Authors: Hermisson Mirjam , Klumpp Andrea , Wick Wolfgang , Wischhusen Jörg , Nagel Georg , Roos Wynand , Kaina Bernd , Weller Michael
Published: January 2006

Temozolomide (TMZ) is a methylating agent which prolongs survival when administered during and after radiotherapy in the first‐line treatment of glioblastoma and which also has significant activity in recurrent disease. O6‐methylguanine DNA methyltransferase (MGMT) is a DNA repair enzyme attributed a role in cancer cell resistance to O6‐alkylating agent‐based chemotherapy. Using a panel of 12 human glioma cell lines, we here defined the sensitivity to TMZ in acute cytotoxicity and clonogenic survival assays in relation to MGMT, mismatch repair and p53 status and its modulation by dexamethasone, irradiation and BCL‐XL. We found that the levels of MGMT expression were a major predictor of TMZ sensitivity in human glioma cells. MGMT activity and clonogenic survival after TMZ exposure are highly correlated (p < 0.0001,r2 = 0.92). In contrast, clonogenic survival after TMZ exposure does not correlate with the expression levels of the mismatch repair proteins mutS homologue 2, mutS homologue 6 or post‐meiotic segregation increased 2. The MGMT inhibitor O6‐benzylguanine sensitizes MGMT‐positive glioma cells to TMZ whereas MGMT gene transfer into MGMT‐negative cells confers protection. The antiapoptotic BCL‐XLprotein attenuates TMZ cytotoxicity in MGMT‐negative LNT‐229 but not in MGMT‐positive LN‐18 cells. Neither ionizing radiation (4 Gy) nor clinically relevant concentrations of dexamethasone modulate MGMT activity or TMZ sensitivity. Abrogation of p53 wild‐type function strongly attenuates TMZ cytotoxicity. Conversely, p53 mimetic agents designed to stabilize the wild‐type conformation of p53 sensitize glioma cells for TMZ cytotoxicity. Collectively, these results suggest that the determination of MGMT expression and p53 status will help to identify glioma patients who will or will not respond to TMZ.
Interleukin‐1 beta‐induced expression of the prostaglandin E2‐receptor subtype EP3 in U373 astrocytoma cells depends on protein kinase C and nuclear factor‐kappaB
Authors: Waschbisch Anne , Fiebich Bernd L. , Akundi Ravi Shankar , Schmitz M. Lienhard , Hoozemans Jeroen J. M. , Candelario‐Jalil Eduardo , Virtainen Nina , Veerhuis Robert , Slawik Helen , Yrjänheikki Juha , Hüll Michael
Published: January 2006

Both interleukin‐1β (IL‐1β) and prostaglandins (PGs) are important mediators of physiological and pathophysiological processes in the brain. PGE2 exerts its effects by binding to four different types of PGE2 receptors named EP1–EP4. EP3 has found to be expressed in neurons, whereas expression of EP3 in glial cells has not been reported in the brain yet. Here we describe IL‐1β‐induced EP3 receptor expression in human astrocytoma cells, primary astrocytes of rat and human origin and in rat brain. Using western blot, we found a marked up‐regulation of EP3 receptor synthesis in human and rat primary glial cells. Intracerebroventricular administration of IL‐1β stimulated EP3 receptor synthesis in rat hippocampus. The analysis of involved signal transduction pathways by pathway‐specific inhibitors revealed an essential role of protein kinase C and nuclear factor‐κB in astrocytic IL‐1β‐induced EP3 synthesis. Our data suggest that PGE2 signaling in the brain may be altered after IL‐1β release due to up‐regulation of EP3 receptors. This might play an important role in acute and chronic conditions such as cerebral ischemia, traumatic brain injury, HIV‐encephalitis, Alzheimer's disease and prion diseases in which a marked up‐regulation of IL‐1β is followed by a prolonged increase of PGE2 levels in the brain.
Septal networks: relevance to theta rhythm, epilepsy and Alzheimer's disease
Authors: Colom Luis V.
Published: January 2006

Information processing and storing by brain networks requires a highly coordinated operation of multiple neuronal groups. The function of septal neurons is to modulate the activity of archicortical (e.g. hippocampal) and neocortical circuits. This modulation is necessary for the development and normal occurrence of rhythmical cortical activities that control the processing of sensory information and memory functions. Damage or degeneration of septal neurons results in abnormal information processing in cortical circuits and consequent brain dysfunction. Septal neurons not only provide the optimal levels of excitatory background to cortical structures, but they may also inhibit the occurrence of abnormal excitability states.
A Nationwide Assessment of the Biodiversity Value of Uganda's Important Bird Areas Network
Authors: TUSHABE HERBERT , KALEMA JAMES , BYARUHANGA ACHILLES , ASASIRA JOSEPHINE , SSEGAWA PAUL , BALMFORD ANDREW , DAVENPORT TIM , FJELDSÅ JON , FRIIS IB , PAIN DEBORAH , POMEROY DEREK , WILLIAMS PAUL , WILLIAMS CHARLES
Published: January 2006

Abstract:  BirdLife International's Important Bird Areas (IBA) program is the most developed global system for identifying sites of conservation priority. There have been few assessments, however, of the conservation value of IBAs for nonavian taxa. We combined past data with extensive new survey results for Uganda's IBAs in the most comprehensive assessment to date of the wider biodiversity value of a tropical country's IBA network. The combined data set included more than 35,000 site × species records for birds, butterflies, and woody plants at 86 Ugandan sites (23,400 km2), including 29 of the country's 30 IBAs, with data on additional taxa for many sites. Uganda's IBAs contained at least 70% of the country's butterfly and woody plant species, 86% of its dragonflies and 97% of its birds. They also included 21 of Uganda's 22 major vegetation types. For butterflies, dragonflies, and some families of plants assessed, species of high conservation concern were well represented (less so for the latter). The IBAs successfully represented wider biodiversity largely because many have distinctive avifaunas and, as shown by high cross‐taxon congruence in complementarity, such sites tended to be distinctive for other groups too. Cross‐taxon congruence in overall species richness was weaker and mainly associated with differences in site size. When compared with alternative sets of sites selected using complementarity‐based, area‐based, or random site‐selection algorithms, the IBA network was efficient in terms of the number of sites required to represent species but inefficient in terms of total area. This was mainly because IBA selection considers factors other than area, however, which probably improves both the cost‐effectiveness of the network and the persistence of represented species.
Computed Tomographic Evaluation of Canine Radioulnar Incongruence In Vivo
Authors: KRAMER ALON , HOLSWORTH IAN G. , WISNER ERIK R. , KASS PHILLIP H. , SCHULZ KURT S.
Published: January 2006

Objective—To compare radioulnar incongruence (RUI) of normal canine elbows and elbows with arthroscopically confirmed medial compartment disease in vivo using systematic computed tomography (CT) measurements.

Study Design—Prospective comparison of RUI measurements in normal and dysplastic canine elbows.

Sample Population—Right elbows of 25 medium–large breed, adult dogs with medial compartment disease and 9 medium–large breed, adult dogs with no elbow disease.

Methods—Transverse CT images of proximal radioulnar articulation were reformatted to dorsal and sagittal planes. RUI in 3 locations of the forelimb's medial coronoid was measured. Arthroscopy confirmed diagnosis of medial compartment disease in the diseased group. RUI measurements of the diseased and normal elbows were compared.

Results—Cumulative statistical analysis of RUI in all planes revealed no significant difference between the normal and abnormal elbows (P=.61). The abnormal elbows had negative mean RUI at the mid (P=.56) and cranial (P=.24) coronoid regions that were not significantly different from normal elbows and mean positive RUI at the base coronoid that was significantly greater than in normal elbows (P=.00082).

Conclusion—Canine elbows with established medial compartment disease do not have significant RUI at the medial coronoid region at the time of diagnosis when compared with normal elbows.

Clinical Relevance—If RUI is a significant factor in the pathophysiology of medial compartment elbow disease in the dog, it does not appear to be present at the time of diagnosis of disease. Ulnar or radial osteotomies do not appear to be indicated for restoration of normal radioulnar articular surface alignment.
In Vitro Comparison of Two Techniques for Suture Prosthesis Placement in the Muscular Process of the Equine Arytenoid Cartilage
Authors: ROSSIGNOL FABRICE , PERRIN ROLAND , DESBROSSE FRANCIS , ELIE CAROLINE
Published: January 2006

Objective—To compare in vitro the load necessary for a partial and complete rupture of the muscular process arytenoid cartilage when a suture prosthesis is positioned by a bone trocar versus a trocar point needle and to compare failure mode.

Study Design—Experimental using cadaver specimens.

Sample Population—Larynges from 18 Thoroughbred race horses, aged 2–20 years.

Methods—Arytenoid cartilages were separated randomly into 2 groups: group 1—suture prosthesis inserted directly through the muscular process using a curved trocar point needle and group 2—suture passed through a hole predrilled with a 3 mm bone trocar. Distracting force (constant rate, 1 mm/s) was applied to the suture until failure of the muscular process. Partial failure load, maximum load at complete failure, and force–time curve were recorded. Each arytenoid cartilage was examined, radiographed, and classified as having a linear or curved failure plane.

Results—No significant differences in mechanical test variables were detected. Failure mode followed the fissures occurring at the beginning of failure and then followed the tension axis. Significantly more linear failures occurred in group 2 (trocar) and more curved failures occurred in group 1 (needle).

Conclusion—Use of a bone trocar for tunneling through the muscular process may reduce fissure formation.

Clinical Relevance—Use of bone trocar to create a hole in the muscular process of the arytenoid cartilage for suture passage in laryngoplasty may reduce fissure formation and decrease the risk of cartilage failure from suture pullout.
Redundancy in Designs
Authors: Yellman Ted W.
Published: January 2006

The author contends that a previous Risk Analysis article overemphasized the pitfalls of incorporating redundancy into designs. Relevant aspects of that article are reviewed and commented upon, then the potentials and pitfalls of redundancy in systems and procedures are more broadly discussed. To provide a solid foundation for that discussion, some definitions for systems risk analysis terminology are presented. It is shown that pairs and larger sets of related failures (the physical causes of shortfalls in redundancy effectiveness) can be divided into two types: (1) cascading/induced failures and (2) common‐external‐cause failures. Each type has its own physical characteristics and implications for mathematical modeling. Service experience with large‐commercial‐airplane jet‐engine propulsion systems is used to illustrate the two types of related failures. Finally, an overview is provided of event‐sequence analysis, an alternative approach to systems risk analysis. When the possibility of related failures of mutually‐redundant system elements must be accounted for, event‐sequence analysis can usually do that better than fault‐tree analysis.
Idiopathic Dilatation of Right Atrium with Atrial Standstill Presenting as Stroke
Authors: Sajeev Chakanalil Govindan , Francis Johnson , Sankar Vikram , Khadar Abdul , Vasudev Babu , Venugopal Krishnan Nair
Published: January 2006

A 48‐year‐old lady presenting with stroke was found to have idiopathic dilatation of right atrium with atrial standstill.
Diastolic Function in Young Patients with Beta‐Thalassemia Major: An Echocardiographic Study
Authors: Chrysohoou Christina , Greenberg Michael , Pitsavos Christos , Panagiotakos Demosthenes B. , Ladis Vasilios , Barbetseas John , Brili Stella , Singh Steven , Stefanadis Christodoulos
Published: January 2006

Objective: We aimed to evaluate myocardial diastolic function in patients with beta‐thalassemia major (β‐TM) using pulsed‐tissue Doppler imaging (TDI) and flow propagation (VP), in relation to BNP levels. Methods: We enrolled 192 consecutive patients with β‐TM (88 men (25 ± 6 years) and 104 women (26 ± 6 years), with normal left ventricular (LV) systolic function. By TDI, diastolic myocardial velocities were sampled at the lateral section of the mitral annulus (Smv, Emv, Amv). From the apical four‐chamber view diastolic transmitral flow velocities, including measures of E‐ and A‐waves were performed. The propagation velocity of early flow into the LV cavity was measured by color M‐mode Doppler. Plasma BNP levels were measured in all patients. Results: A nonlinear relationship was found between BNP levels and E/A ratio (beta coefficient for the second‐order term = 1.4 ± 0.4, P = 0.001). We also found a positive association of BNP levels with Amv (r = 0.28, P = 0.023), and a reverse with Smv (r =−0.59, P = 0.01) and Emv/Amv (r =−0.36, P = 0.019). Moreover, an inverse relationship was observed between BNP and Vp (r =−0.43, P = 0.012) levels. Finally, a strong positive linear relationship was found between E/Vp ratio and BNP levels (r = 0.76, P < 0.001). Conclusion: A U‐curved association of E/A ratio of transmitral Doppler velocity was revealed with BNP levels, while the tissue Doppler of the Emv/Amv of the mitral annulus movement showed a negative linear association with BNP levels.
Prosthetic treatment of maxillary lateral incisor agenesis with osseointegrated implants: a 24–39‐month prospective clinical study
Authors: Zarone Fernando , Sorrentino Roberto , Vaccaro Francesco , Russo Simona
Published: January 2006

Objectives: The present study aimed at evaluating the marginal bone resorption and the peri‐implant tissue conditions around Narrow‐Neck ITI implants in the implant–prosthetic treatment of the agenesis of maxillary lateral incisors.

Material and methods: Thirty patients affected by monolateral or bilateral agenesis of the maxillary lateral incisors were selected. Thirty‐four ITI‐SLA Narrow Neck implants were inserted and loaded about 4 months after the surgical procedure. The final restorations were realized using Aureo Galvan Crowns veneered with feldspathic ceramics. The follow‐up period ranged from 24 to 39 months. Both marginal bone resorption and soft tissue quality were evaluated. The data were statistically analysed using analysis of variance (ANOVA) for repeated measures, one‐way ANOVA and Tukey's post hoc test (P=0.05).

Results: During the 24–39‐month follow‐up period, no implant showed either pain and sensitivity or mobility. After 39 months of functional loading, a cumulative survival rate of 97.06% and a cumulative success rate of 94.12% were calculated.

Conclusions: In case of maxillary lateral incisor agenesis, the implant–prosthetic approach has proved to be a reliable and predictable treatment for both re‐establishment of function and aesthetics. Satisfactory values of marginal bone resorption over time and optimal conditions of peri‐implant tissue around Narrow‐Neck ITI implants were found.
The Nested Superblock Approach for Regional‐Scale Analytic Element Models
Authors: Craig James R. , Janković Igor , Barnes Randal
Published: January 2006

A new approach is presented for improving the computational efficiency of regional‐scale ground water models based on the analytic element method (AEM). The algorithm is an extension of the existing “superblock” algorithm, which combines the effects of multiple analytic elements into Laurent series and Taylor series (superblock expansions). With the new “nested superblock” formulation, Laurent series are nested in a hierarchical (quad‐tree) data structure with direct mathematical relationships between parent and child superblock coefficients. Nested superblocks significantly accelerate the evaluation of the complex potential and discharge function in models that contain a large number of analytic elements at multiple scales. This evaluation process, the primary computational cost of AEM models, is required to determine the element coefficients, generate contour plots, and trace pathlines. The performance of the nested superblocks is demonstrated with a simplified model based on the Lake Ontario watershed geometry comprising thousands of hydrogeologic features at multiple geographic scales.
Ground Water Modeling Applications Using the Analytic Element Method
Authors: Hunt Randall J.
Published: January 2006

Though powerful and easy to use, applications of the analytic element method are not as widespread as finite‐difference or finite‐element models due in part to their relative youth. Although reviews that focus primarily on the mathematical development of the method have appeared in the literature, a systematic review of applications of the method is not available. An overview of the general types of applications of analytic elements in ground water modeling is provided in this paper. While not fully encompassing, the applications described here cover areas where the method has been historically applied (regional, two‐dimensional steady‐state models, analyses of ground water–surface water interaction, quick analyses and screening models, wellhead protection studies) as well as more recent applications (grid sensitivity analyses, estimating effective conductivity and dispersion in highly heterogeneous systems). The review of applications also illustrates areas where more method development is needed (three‐dimensional and transient simulations).
The Synergistic Powers of AEM and GIS Geodatabase Models in Water Resources Studies
Authors: Steward David R. , Bernard Eric A.
Published: January 2006

Comprehensive studies of water resources systems require integration of modeling tools and data associated with individual processes. An object‐oriented approach is presented here that associates ground water models based upon the analytic element method (AEM) with geographic information system (GIS) geodatabase features using an AEM Model Interface. Each aquifer object contains a prescribed geometry, a mathematical representation in the AEM, and GIS hydrogeologic data. The synergistic understanding inherent in such an approach is illustrated by a study linking local AEM model predictions of water elevation with ground water geodatabase objects. This AEM Model Interface provides a key component in establishing a common object‐oriented geodatabase modeling approach linking ground water to a variety of natural and social processes.
VIRTUAL KNOT DIAGRAMS AND THE WITTEN–RESHETIKHIN–TURAEV INVARIANT
Authors: DYE H. A. , KAUFFMAN LOUIS H.
Published: January 2006

The Witten–Reshetikhin–Turaev invariant of classical link diagrams is generalized to virtual link diagrams. This invariant is unchanged by the framed Reidemeister moves and the Kirby calculus. As a result, it is also an invariant of the 3-manifolds represented by the classical link diagrams. This generalization is used to demonstrate that there are virtual knot diagrams with a non-trivial Witten–Reshetikhin–Turaev invariant and trivial 3-manifold fundamental group.
AN AB INITIO STUDY OF CHARGE STATE EFFECTS ON THE USE OF ${\rm Ag}_{2}^{+}$ AND Ag2 FOR CATALYTIC OXIDATION OF CO
Authors: DHOLABHAI PRATIK P. , RAY ASOK K.
Published: January 2006

The formalism of density functional theory (DFT) with Perdew and Wang exchange-correlation functional, has been employed to study the electronic and geometric structures of silver cation and the neutral dimer bonded with carbon monoxide and oxygen. A charge state study of the use of [Formula: see text] and Ag 2, for the catalytic oxidation of CO , has been performed and compared with our previous results for [Formula: see text]. Different possible structures for [Formula: see text], Ag 2 CO +, Ag 2 O 2 and Ag 2 CO have been investigated in detail. An all electron 6-311 ++ G ** basis set for carbon and oxygen, and a pseudopotential basis set for silver have been used for performing the calculations. Using silver cation and neutral dimer as catalysts, full catalytic cycles producing two carbon dioxide molecules have been presented. Also, the presence of intermediate states, [Formula: see text] and Ag 2 CO 3, which can be detected experimentally, are predicted. The presence of an energy barrier for certain reactions from the catalytic cycle have been observed. This is noteworthy since no reaction barrier has been observed using silver anion dimer as a catalyst, for the same catalytic cycle. Analyzing the charge state effects, it is concluded that silver anion dimer performs better as a catalyst, compared with silver cation and neutral dimers.
Bioenergetic and functional consequences of stem cell-based VEGF delivery in pressure-overloaded swine hearts
Authors: Wang Xiaohong , Hu Qingsong , Mansoor Abdul , Lee Joseph , Wang Zongli , Lee TeChung , From Arthur H. L. , Zhang Jianyi
Published: December 2005

In an established swine model of severe left ventricular (LV) hypertrophy (LVH), the bioenergetic and functional consequences of transplanting autologous mesenchymal stem cells (MSCs) overexpressing vascular endothelial growth factor (VEGF-MSCs) into the LV were evaluated; transplantation was accomplished by infusion of VEGF-MSCs into the interventricular cardiac vein. Specifically, the hypertrophic response to aortic banding was compared in seven pigs treated with 30 million VEGF-MSCs, eight pigs treated with 30 million MSCs without VEGF modification, and 19 untreated LVH pigs. Eight pigs without banding or cell transplantation (normal) were also studied. Four weeks postbanding, LV wall thickening (MRI), myocardial blood flow (MBF), high-energy phosphate levels (31P magnetic resonance spectroscopy), and hemodynamic measurements were obtained under basal conditions and during a catecholamine-induced high cardiac workstate (HCW). Although 9 of 19 untreated banded pigs developed clinical evidence of biventricular failure, no MSCs-treated animal developed heart failure. MSCs engraftment was present in both cell transplant groups, and both baseline and HCW MBF values were significantly increased in hearts receiving VEGF-MSCs compared with other groups ( P < 0.05). During HCW, cardiac inotropic reserve (defined as the percent increase of rate pressure product at HCW relative to baseline) was normal in the VEGF-MSCs group and significantly decreased in all other banded groups. Additionally, during HCW, the myocardial energetic state [reflected by the phosphocreatine-to-ATP ratio (PCr/ATP)] of VEGF-MSCs-treated hearts remained stable, whereas in all other groups, PCr/ATP decreased significantly from baseline values ( P < 0.05, each group). Myocardial von Willebrand factor and VEGF mRNA expressions and myocardial capillary density were significantly increased in VEGF-MSCs-treated hearts ( P < 0.05). Hence, in the pressure-overloaded LV, transplantation of VEGF-MSCs prevents LV decompensation, induces neovascularization, attenuates hypertrophy, and improves MBF, myocardial bioenergetic characteristics, and contractile performance.
Coronary spasm reflects inputs from adjacent esophageal system
Authors: Manfrini Olivia , Bazzocchi Gabriele , Luati Alessandra , Borghi Alberigo , Monari Paola , Bugiardini Raffaele
Published: December 2005

Mechanisms underlying coronary spasm are still poorly understood. The aim of the study was to assess the hypothesis that fluctuations in the development of coronary spasm might reflect inputs from the adjacent esophageal system. We enrolled patients admitted to the coronary care unit for episodes of nocturnal angina. Seven patients with variant angina and five with coronary artery disease (CAD) had concurrent ECG and esophageal manometric monitoring. ECG monitoring documented 28 episodes of ST elevation in variant angina patients and 16 episodes of ST depression in CAD patients. Manometric analysis showed that esophageal spasms resulted remarkably more frequently in variant angina patients (143 total spasms; individual range 9–31) than in CAD patients (20 total spasms; individual range 0–9; P < 0.01). Time series analysis was used to assess fluctuations in the occurrence of abnormal esophageal waves and its relationship with spontaneous episodes of ST shift. Episodes of esophageal spasm in CAD were sporadic (<1 in 30 min) and not related to ECG-recorded ischemia. In the variant angina group, esophageal spasms were time related to ischemia (>1 into 5 min before ECG-recorded ischemia) ( P < 0.05). A bidirectional analysis of causal effects showed that the influence processes between esophageal and coronary spasms were mutual and reciprocal (transfer function model, P < 0.05) in variant angina. We concluded that in variant angina patients, episodes of esophageal spasms and myocardial ischemia influenced each other. Mechanisms that cause esophageal spasm can feed back to produce coronary spasm. Coronary spasm may feed forward to produce additional episodes of esophageal spasm.
Subdepressor dose of benidipine ameliorates diabetic cardiac remodeling accompanied by normalization of upregulated endothelin system in rats
Authors: Jesmin Subrina , Hattori Yuichi , Maeda Seiji , Zaedi Sohel , Sakuma Ichiro , Miyauchi Takashi
Published: December 2005

We investigated whether benidipine, a long-acting calcium channel blocker (CCB), can normalize cardiac expression profiles of the endothelin (ET)-1 system in insulin-resistant diabetes. Otsuka Long-Evans Tokushima Fatty (OLETF) rats, a model of human Type 2 diabetes, were treated for 12 wk with vehicle or benidipine (3 mg·kg−1·day−1). OLETF rats exhibited a significant increase in ET-1 in plasma and left ventricular (LV) tissues compared with nondiabetic controls. Expression of prepro-ET-1, ET-converting enzyme, and ETAand ETBreceptors in LV tissues was also significantly higher in OLETF rats. The two MAPKs, JNK and p38MAPK, both of which are activated by ET-1, were more abundantly expressed in OLETF rat LV tissues. All these alterations were reversed to nondiabetic levels when OLETF rats were treated with the subdepressor dose of benidipine. Furthermore, benidipine therapy resulted in hindering cardiomyocyte hypertrophy and cardiac perivascular fibrosis in OLETF rats. The beneficial actions of benidipine at the subdepressor dose on cardiac remodeling in insulin-resistant diabetes may involve normalization of the upregulated ET-1 system.
Desmin modulates lung elastic recoil and airway responsiveness
Authors: Shardonofsky Felix R. , Capetanaki Yassemi , Boriek Aladin M.
Published: December 2005

Desmin is a structural protein that is expressed in smooth muscle cells of both airways and alveolar ducts. Therefore, desmin could be well situated to participate in passive and contractile force transmission in the lung. We hypothesized that desmin modulates lung compliance, lung recoil pressure, and airway contractile response. To test this hypothesis, respiratory system complex impedance (Zin,rs) at different positive end-expiratory pressure (PEEP) levels and quasi-static pressure-volume data were obtained in desmin-null and wild-type mice at baseline and during methacholine administration. Airways and lung tissue properties were partitioned by fitting Zin,rs to a constant-phase model. Relative to controls, desmin-null mice showed 1) lower values for lung stiffness and recoil pressure at baseline and induced airway constriction, 2) greater negative PEEP dependence of H and airway resistance under baseline conditions and cholinergic stimulation, and 3) airway hyporesponsiveness. These results demonstrate that desmin is a load-bearing protein that stiffens the airways and consequently the lung and modulates airway contractile response.
Rayleigh waves in a viscoelastic half‐space under initialhydrostatic stress in presence of the temperature field
Authors: Addy Sushil Kumar , Chakraborty Nil Ratan
Published: January 2006

The effect of the temperature and initial hydrostatic stress has been shown
on the propagation of Rayleigh waves in a viscoelastic half‐space. It has been explained
how the velocity of Rayleigh waves depends not only on the parameters pertaining to the
viscoelastic properties of the half‐space, but on the temperature and the initial hydrostatic
stress of the half‐space also. The variations of the phase velocity of Rayleigh waves in
dimensionless form with respect to the magnitude of the initial hydrostatic stress under
certain practical assumptions have been depicted in graphs after numerical computations.
If the temperature and the initial hydrostatic stress of the half‐space are neglected, the
results obtained are in perfect agreement with the classical case as obtained by Caloi for
the propagation of Rayleigh waves in a viscoelastic medium.
Nonwandering operators in Banach space
Authors: Tian Lixin , Zhou Jiangbo , Liu Xun , Zhong Guangsheng
Published: January 2006

We introduce nonwandering operators in infinite‐dimensional separable
Banach space. They are new linear chaotic operators and are relative to hypercylic
operators, but different from them. Firstly, we show some examples for nonwandering
operators in some typical infinite‐dimensional Banach spaces, including Banach
sequence space and physical background space. Then we present some
properties of nonwandering operators and the spectra decomposition
of invertible nonwandering operators. Finally, we obtain that
invertible nonwandering operators are locally structurally stable.
Equivalence among some neighborhood structures in fuzzy topology
Authors: De Mitri Cosimo
Published: January 2006

We deepen the study of two known neighborhood structures, which
here will be called f · k‐neighborhood structures and f · q‐neighborhood structures, in the context of Šostak fuzzy
topological spaces. In particular, we characterize fuzzy
topologies by f · k‐neighbor‐hood structures. Moreover we introduce and discuss the notions of
f · k‐neighborhood prestructure and f · m‐neighborhood structure in the same context. At last we prove that the three
neighborhood structures mentioned above are equivalent.
Boundary behavior of capillary surfaces possibly with extremal boundary angles
Authors: Liang Fei-Tsen
Published: January 2006

For solutions to the capillarity problem possibly with the
boundary contact angle θ being 0 and/or π in a relatively open portion of the boundary which is C2, we will show that if the solution is locally bounded up to this portion of
boundary, the trace of the solution on this portion is piecewise
Lipschitz continuous and the solution is Hölder continuous up to
the boundary, provided the prescribed mean curvature is bounded
from above and from below. In the case where θ is not required to be bounded away from π/2, 0, and π, and the mean curvature H(x, t0) belongs to Lp(Ω) for some t0 ∈ ℝ and p > n, under the assumption that in a neighborhood of a relatively open portion of the
boundary the solution is of rotational symmetry, the trace of the solution on
this portion of the boundary is shown to be Hölder continuous with exponent
1/n if n ≥ 3 and with exponent 1/3 if n = 2.
On reducibility of some operator semigroups and algebras onlocally convex spaces
Authors: Kramar Edvard
Published: January 2006

A generalization of some results from normed spaces, concerning
reducibility and triangularizability of semigroups and algebras of
operators, to locally convex spaces is given.
Fuzzy n‐normed linear space
Authors: Narayanan AL. , Vijayabalaji S.
Published: January 2006

The primary purpose of this paper is to introduce the notion of
fuzzy n‐normed linear space as a generalization of n‐normed
space. Ascending family of α‐n‐norms corresponding to fuzzy n‐norm is introduced. Best approximation sets in
α‐n‐norms are defined. We also provide some results on
best approximation sets in α‐n‐normed space.
Coassociative grammar, periodic orbits, and quantum randomwalk over ℤ
Authors: Leroux Philippe
Published: January 2006

Inspired by a work of Joni and Rota, we show that the
combinatorics generated by a quantisation of the Bernoulli random
walk over ℤ can be described from a coassociative coalgebra. Relationships between this
coalgebra and the set of periodic orbits of the classical chaotic system x ↦ 2x mod⁡1, x ∈ [0, 1], are also given.
Properties of rational arithmetic functions
Authors: Laohakosol Vichian , Pabhapote Nittiya
Published: January 2006

Rational arithmetic functions are arithmetic functions of the form
, where gi, hj are completely multiplicative functions and
∗ denotes the Dirichlet convolution. Four aspects of these
functions are studied. First, some characterizations of such
functions are established; second, possible Busche‐Ramanujan‐type
identities are investigated; third, binomial‐type identities are
derived; and finally, properties of the Kesava Menon
norm of such functions are proved.
Completions of non‐T2 filter spaces
Authors: Rath Nandita
Published: January 2006

The well‐known completions of T2 Cauchy spaces and T2 filter spaces are extended to the completions of non‐T2 filter spaces, and a completion functor on the category of all
filter spaces is described.
Common fixed point theorems for nonself‐mappings in metrically convex spaces via altering distances
Authors: Imdad M. , Khan Ladlay
Published: January 2006

Some common fixed point theorems for a pair of nonself‐mappings in complete metrically convex metric spaces are proved by alte ring distances between the points, which generalize earlier results due to M. D. Khan and Bharadwaj (2001), M. S. Khan et al. (2000), Bianchini (1972), Chatterjea 1972, and others. Some related results are also discussed besides furnishing an illustrative example.
Compatible elements in partly ordered groups
Authors: Močkoř Jiří , Kontolatou Angeliki
Published: January 2006

Some conditions equivalent to a strong quasi‐divisor property (SQDP) for a partly ordered group G are derived. It is proved that if G is defined by a family of t‐valuations of finite character, then G admits an SQDP if and only if it admits a quasi‐divisor property and any finitely generated t‐ideal is generated by two elements. A topological density condition in topological group of finitely generated t‐ideals and/or compatible elements are proved to be equivalent to SQDP.
Long‐term dependence in exchange rates
Authors: Karytinos A. , Andreou A. S. , Pavlides G.
Published: January 2006

The extent to which exchange rates of four major currencies against the Greek Drachma exhibit long‐term dependence is investigated using a R/S
analysis testing framework. We show that both classic R/S analysis and the modified R/S statistic if enhanced by bootstrapping techniques can be proven very reliable tools to this end. Our findings support persistence and long‐term dependence with non‐periodic cycles for the Deutsche Mark and the French Franc series. In addition a noisy chaos explanation is favored over fractional Brownian motion. On the contrary, the US Dollar and British Pound were found to exhibit a
much more random behavior and lack of any long‐term structure.
Chaotic numerical instabilities arising in the transition from differential to difference nonlinear equations
Authors: de Markus Alicia Serfaty
Published: January 2006

For computational purposes, a numerical algorithm maps a differential equation into an often complex difference equation whose structure and stability depends on the scheme used. When considering nonlinear models, standard and nonstandard integration routines can act invasively and numerical chaotic instabilities may arise. However, because nonstandard schemes offer a direct and generally simpler finite‐difference representations, in this work nonstandard constructions were tested over three different systems: a photoconductor model, the Lorenz equations and the Van der Pol equations. Results showed that although some nonstandard constructions created a chaotic dynamics of their own, there was found a construction in every case that greatly reduced or successfully removed numerical chaotic instabilities. These improvements represent a valuable development to incorporate into more sophisticated algorithms.
A preliminary nonlinear analysis of the earth′s chandler wobble
Authors: Frede V. , Mazzega P.
Published: January 2006

The Chandler wobble (CW) is a resonant response of the Earth rotational pole wandering around its figure axis whose excitation mechanism is still uncertain. It appears as polar motion oscillations with an average period of about 433 days and a slowly varying amplitude in the range (0–300) milliarcsec (mas). We here perform a nonlinear analysis of the CW via a time‐delay coordinate embedding of its measured X and Y components and show that the CW can be interpreted as a low dimensional unstable deterministic process.

In a first step the trend, annual wobble and CW are separated from the raw polar motion data time series spanning the period 1846–1997. The optimal delays as deduced from the average mutual information function are 105 and 115 days for the X and Y components respectively. Then from the global statistics of the false neighbours, the embedding dimension DE = 4 is estimated for both series. The local dimension DL can also be extracted from the time series by testing the predictive skill of local mappings fitted to the embedded data vectors. The result DL = 3 is quite robust and corroborate the idea that the CW behaves like a dissipative oscillator driven by a deterministic process. Indeed the orbit reconstructions in pseudo‐phase space both draw the figure of a perturbated 1‐torus.

The computation of the Lyapunov spectra further shows that this torus‐like figure is an attractor with a 1D unstable manifold. The theoretical horizons of prediction deduced from the (positive) principal exponents are about 367 and 276 days for the X and Y Chandler components respectively. Moreover the local Lyapunov exponents exhibit significant variations with maxima (and corresponding losses of predictibility) in the decades 1860–1870 and 1940–1950.
The study of bray–Liebhafsky reaction over a wide range of temperatures. II. modelling
Authors: Vîlcu R. , Danciu T. , Bala D.
Published: January 2006

From a preview of proposed models a molecular one (involving neither ions nor free radicals) was chosen. The concept of scaled concentrations for intermediates is introduced. A different mechanism (involving Dushman reaction) is proposed for the ignition period.
Monitoring the complexity of ventricular response in atrial fibrillation
Authors: Käsmacher H. , Wiese S. , Lahl M.
Published: January 2006

Atrial fibrillation does not present a uniform extent of variability of the ventricular response exemplifying periodicities and more complex fluctuations, due to varying number and shape of atrial wavelets and aberrant conduction in the AV‐junction. It was sought to categorise different degrees of complexity introducing an uncomplicated monitoring method for that
objective.

The fluctuation of RR‐intervals was investigated in 66 patients presenting with atrial fibrillation at different times of the day using conventional statistical methods as well as methods derived from non‐linear dynamics. Specifically Poincaré‐plots were employed to analyse the data. One hundred and seventy data sets consisting of 5000–8000 intervals each were considered.

Statistical methods were shown to describe the observed dynamics not adequately due to background noise in the acquired data as well as owing to intrinsic qualities of the data sets. Namely non‐uniformly distributed data and trends within the data sets constituted limitations of statistical methods.

Poincaré‐plots were proven to be an inexpensive and effective method to categorise the complexity of the ventricular response in atrial fibrillation. Periodical variation of interval lengths could be clearly differentiated from continuous variation in the considered data sets. The latter could be shown to exemplify either stochastic fluctuation or complex non‐linear dynamics of RR‐interval variation. Thus, different degrees of complexity could be clearly distinguished.

It could be shown exemplary that the observed dynamics remained nearly constant within the observation period.

Poincaré‐plots, thus, provide a means to appreciate the fluctuation of RR‐intervals semiquantitatively and to distinguish different patterns of fluctuation dynamics of the ventricular response in atrial fibrillation without being affected by contaminated or inconsistent data.

For a complete visualisation of the concerned dynamics relatively small data sets suffice. Thus, it is possible to observe the pattern of fluctuation essentially in real time which makes them ideally suited for future investigation.
Chaos and maps in relativistic rynamical systems
Authors: Horwitz L. P. , Ashkenazy Y.
Published: January 2006

The basic work of Zaslavskii et al showed that the classical non‐relativistic electromagnetically kicked oscillator can be cast into the form of an iterative map on the phase space; the resulting evolution contains a stochastic flow to unbounded energy. Subsequent
studies have formulated the problem in terms of a relativistic charged particle in interaction with the electromagnetic field. We review the structure of the covariant Lorentz force used to study this problem. We show that the Lorentz force equation can be derived as well from the manifestly covariant mechanics of Stueckelberg in the presence of a standard Maxwell field, establishing a connection between these equations and mass shell constraints. We argue that these relativistic generalizations of the problem are intrinsically inaccurate due to an inconsistency in the structure of the relativistic Lorentz force, and show that a reformulation of the relativistic problem, permitting variations (classically) in both the particle mass and the effective “mass” of the interacting electromagnetic field, provides a consistent system of classical equations for describing such processes.
Deliberate ambiguity in a finite environment: The urban ecology of artificial items
Authors: Akkerman Abraham
Published: January 2006

A distinction is made between visual declaration and virtual usage of artificial items within a physical environment, such as a street. Visual declaration is a formal pictorial designation, or a function, e.g. “decoration,” of an item, such as a “planter.” Virtual usage refers to the item when it is used in lieu of another item. The formal designation, “sitting,” customarily designated to an item such as “bench,” could also be a virtual usage of the item “planter.” The question asked is, “What is the relationship between items, given their formal, visual declaration and their informal, virtual, usage?” An artificial item, according to its visual declaration, is referred to as a ‘visual’ or ‘real item’. Each visual item has the property of being used as another item by virtue of its undeclared usage. Pending on the item′s design and configuration, a visual item can be then substituted for another visual item. An artificial item, thus, attains deliberate ambiguity between its formal designation and its virtual usage. This ambiguity between visual declaration and virtual usage can be quantified. Within the full domain of n possible usages, this relationship can be conveniently presented in a nonnegative matrix. It is shown that the inverse of this matrix belongs to a class of well‐known matrices. This being the case, the relationship between visual and virtual properties of items within the environment can be formalized. The formalization throws further light on the emerging opportunities in streetscape design.