bluuebunny/crossref_metadata_2025 huggingface dataset:
NONCOMMUTATIVE RIGIDITY FOR PHYSICISTS
Authors: HAWKINS ELI
Published: December 2003

The existence of a noncommutative deformation of spacetime geometry implies restrictive compatibility conditions between the metric and the noncommutativity. This has implications for any physical theory which encompasses a noncommutatively deformed spacetime. In particular, it suggests a condition on the metric in at least one limit of string theory.
From the fuzzy disc to edge currents in Chern-Simons Theory
Authors: LIZZI F. , VITALE P. , ZAMPINI A.
Published: December 2003

We present a brief review of the fuzzy disc, the finite algebra approximating functions on a disc, which we have introduced earlier. We also present a comparison with recent papers of Balachandran, Gupta and Kürkçüoǧlu, and of Pinzul and Stern, aimed at the discussion of edge states of a Chern-Simons thoery.
Yang-Mills theory, 2 + 1 and 3 + 1 dimensions
Authors: NAIR V. P.
Published: December 2003

I review the analysis of (2+1)-dimensional Yang-Mills (YM2+1) theory via the use of gauge-invariant matrix variables. The vacuum wavefunction, string tension, the propagator mass for gluons, its relation to the magnetic mass for YM3+1at nonzero temperature and the extension of our analysis to the Yang-Mills-Chern-Simons theory are discussed. A possible extension to 3 + 1 dimensions is also briefly considered.
Field Theory on Low Dimensional Fuzzy Spaces
Authors: O'Connor Denjoe
Published: December 2003

A brief summary is given of the currently available low dimensional fuzzy spaces and some of the simplest field theories permitted on these spaces.
GAUGE FIELDS ON THE FUZZY SPHERE
Authors: Prešnajder Peter
Published: December 2003

The free spinor field on a fuzzy sphere is described within Watamura approach to Dirac operator. Except of the highest mode, its spectrum is the same but truncated as in the commutative case. We present a simple gauge extension of the model with usual polynomial interaction. The gauge symmetry is exact, and the chiral properties of the field modes are standard except the highest mode.
Abrikozov Vortex and Branes
Authors: Randjbar-Daemi S.
Published: December 2003

In this contribution in honor of A.P. Balchandran we give a brief description of application of topological solutions in field theory, a subject which has been central to many of Balachandran's important contributions to physics.
From Diffeomorphisms to Dark Energy?
Authors: Rodgers Vincent G. J. , Yasuda Takeshi
Published: December 2003

There are two physical actions that have a natural setting in terms of the coadjoint representation of the algebra of diffeomorphisms and of affine Lie algebras. One is the usual geometric action that comes from coadjoint orbits. The other action lives on the phase space that is transverse to the orbits and are called transverse actions, where Yang-Mills theory in two dimensions is an example. Here we show that the transverse action associated with the Virasoro algebra might contain clues for a theory for dark energy. These actions might also suggests a mechanism for symmetry changing.
GAUGE FIXING AND OBSERVABLES IN GENERAL RELATIVITY
Authors: SALISBURY DONALD
Published: December 2003

The conventional group of four-dimensional diffeomorphisms is not realizeable as a canonical transformation group in phase space. Yet there is a larger field-dependent symmetry transformation group which does faithfully reproduce 4-D diffeomorphism symmetries. Some properties of this group were first explored by Bergmann and Komar. More recently the group has been analyzed from the perspective of projectability under the Legendre map. Time translation is not a realizeable symmetry, and is therefore distinct from diffeomorphism-induced symmetries. This issue is explored further in this paper. It is shown that time is not "frozen". Indeed, time-like diffeomorphism invariants must be time-dependent. Intrinsic coordinates of the type proposed by Bergmann and Komar are used to construct invariants. Lapse and shift variables are retained as canonical variables in this approach, and therefore will be subject to quantum fluctuations in an eventual quantum theory. Concepts and constructions are illustrated using the relativistic classical and quantum free particle. In this example concrete time-dependent invariants are displayed and fluctuation in proper time is manifest.
A String Motivated Approach to the Relativistic Point Particle
Authors: Tuite Michael , Sen Siddhartha
Published: December 2003

Using concepts developed in string theory, Cohen, Moore, Nelson and Polchinski calculated the propagator for a relativistic point particle. Following these authors we extend the technique to include the case of closed world lines. The partition function found corresponds to the Feynmann and Schwinger proper time formalism. We also explicitly verify that the partition function is equivalent to the usual path length action partition function. As an example of a sum over closed world lines, we compute the Euler-Heisenberg effective Lagrangian in a novel way.
Indecomposable Ideals in Incidence Algebras
Authors: Sorkin Rafael D.
Published: December 2003

The elements of a finite partial order P can be identified with the maximal indecomposable two-sided ideals of its incidence algebra [Formula: see text], and then for two such ideals, I ≺ J ⇔ IJ ≠ 0. This offers one way to recover a poset from its incidence algebra. In the course of proving the above, we classify all of the two-sided ideals of [Formula: see text].
Fluctuating Commutative Geometry
Authors: de Albuquerque Luiz C. , deLyra Jorge L. , Teotonio-Sobrinho Paulo
Published: December 2003

We use the framework of noncommutative geometry to define a discrete model for fluctuating geometry. Instead of considering ordinary geometry and its metric fluctuations, we consider generalized geometries where topology and dimension can also fluctuate. The model describes the geometry of spaces with a countable number n of points. The spectral principle of Connes and Chamseddine is used to define dynamics. We show that this simple model has two phases. The expectation value 〈n〉, the average number of points in the universe, is finite in one phase and diverges in the other. Moreover, the dimension δ is a dynamical observable in our model, and plays the role of an order parameter. The computation of 〈δ〉 is discussed and an upper bound is found, 〈δ〉 < 2. We also address another discrete model defined on a fixed d = 1 dimension, where topology fluctuates. We comment on a possible spontaneous localization of topology.
UNITARITY OF NONCOMMUTATIVE FIELD THEORIES FROM STRING THEORY
Authors: TORRIELLI ALESSANDRO
Published: December 2003

We improve the study of the lack of perturbative unitarity of noncommutative space-time quantum field theories derived from open string theory in electric backgrounds, enforcing the universality of the mechanism by which a tachyonic branch cut appears when the Seiberg-Witten limit freezes the string in an unstable vacuum. The main example is realized in the context of the on-shell four-tachyon amplitude of the bosonic string, and the dependence of the phenomenon on the brane-worldvolume dimension is analysed. We discuss the possibility of a proof in superstring theory, and finally mention the NCOS limit in this framework.
SURFACE SUPERCONDUCTING STATES IN MESOSCOPIC SUPERCONDUCTORS UNDER DIFFERENT BOUNDARY CONDITIONS
Authors: ZHAO L. , QIU X. G. , ZHAO B. R.
Published: December 2003

The surface superconductivity of a mesoscopic superconducting cylinder in an external parallel magnetic field is discussed within the framework of the linearized Ginzburg–Landau equation under different boundary conditions. For the superconductor/insulator interface, our calculations give the corrugation-like phase boundary H c3 (T), with oscillating ripples as a result of the switching of the "giant vortex state" wave function between different angular quantum number L. The tangent for the linear background of the phase boundary H c3 (T) is about 1.7 times H c2 (T), consistent with the well-known result in bulk surface superconductivity. For the superconductor/normal-metal interface, surface superconductivity disappears, accompanied by a decrease in the superconducting transition temperature T c (H=0).
CONTROLLABLE SPIN-FILTERING AND MAGNETOCONDUCTANCE IN A NOVEL HYBRID FM/2DEG/FM STRUCTURE
Authors: JIANG Y. , JALIL M. B. A.
Published: December 2003

Spin-dependent ballistic transport is studied for a two-dimensional electron gas (2DEG) heterostructure, sandwiched between two ferromagnetic metal (FM) layers. The device exhibits a strong spin-filtering behavior when the magnetization directions of the FM layers are anti-parallel to one another. Additionally, a pronounced magnetoconductance (MC) effect is predicted when the relative magnetization direction of the FM layers is changed, e.g. by applying an external magnetic field sweep. Both the spin-filter and spin-valve (SV) functions can be tuned externally by adjusting the applied voltage and the fringe field strength from the FM layers. Compared to conventional all-metal SVs, the proposed 2DEG-based SV potentially has the advantages of a higher MC ratio (of as high as 90%), external tenability, and less susceptibility to interfacial imperfections.
POINT-CONTACT SPECTROSCOPY OF MAGNESIUM DIBORIDE WITH DIFFERENT COUNTER-ELECTRODES
Authors: D'YACHENKO A. I. , TARENKOV V. YU. , BELOGOLOVSKII M. A. , VARYUKHIN V. N. , ABAL'OSHEV A. V. , LEWANDOWSKI S. J.
Published: December 2003

We report on tunneling and Andreev-reflection conductance spectra of 39 K superconducting magnesium diboride, obtained with Pb and Au counter-electrodes. Two distinct steps at close to 2.7 and 7.1 meV appear in a low-resistance metallic-type Au–MgB 2 junction characteristic, whereas a tunneling-like spectrum measured for the same junction, annealed by the application of DC current, exhibits only a rounded contribution of the larger gap. Junctions with a superconducting lead counter-electrode pressed into a bulk MgB 2 sample reveal two conductance peaks that are interpreted as the result of the formation of a highly-transmitting break junctions inside the magnesium diboride ceramic. Our results strongly support the two-band model with two different gap values on quasi-two-dimensional σ (7.1 meV) and three-dimensional π (2.7 meV) Fermi surface sheets of MgB 2.
DEVELOPING HEALTH IMPACT ASSESSMENT FOR SUSTAINABLE FUTURES IN SMALL ISLAND STATES AND TERRITORIES
Authors: DOUGLAS CALBERT H
Published: December 2003

This paper argues that small island states and territories provide a case for the application of health impact assessments. Their characteristic ecological fragility, vulnerability, relatively small size and limited resources give cause for environmental impact concerns. The tendency, therefore, is for decision-makers and developers to focus upon the economic benefits of proposed development projects while mitigating their environmental impacts, paying little attention to health impacts. The paper defines health status and health determinants and provides a toolkit of guidelines for carrying out health impact assessment in small islands. It discusses the approaches and lessons from the UK and Canada by which assessors in small islands can develop health impact assessment processes within their own contexts. The paper identifies the positive and negative health impacts that assessors should consider in assessing the impacts from tourism. The conclusions point to policy implications and the need for decision-makers to incorporate health impact assessment into their respective island's planning and regulatory frameworks.
rc‐continuous functions and functions with rc‐strongly closed graph
Authors: Al-Nashef Bassam
Published: December 2003

The family of regular closed subsets of a topological space is
used to introduce two concepts concerning a function f from a
space X to a space Y. The first of them is the notion of f
being rc‐continuous. One of the established results states that a
space Y is extremally disconnected if and only if each
continuous function from a space X to Y is rc‐continuous. The
second concept studied is the notion of a function f having an
rc‐strongly closed graph. Also one of the established results
characterizes rc‐compact spaces (≡S‐closed spaces) in
terms of functions that possess rc‐strongly closed graph.
Impairment of Endothelial Function in Patients with Spontaneous Cervical Artery Dissection: Evidence for a General Arterial Wall Disease
Authors: Lucas C. , Lecroart J.L. , Gautier C. , Leclerc X. , Dauzat M. , Leys D. , Deklunder G.
Published: December 2003

Background and Purpose: Cervical artery dissection (CAD) accounts for 10–20% of ischemic strokes in young adults. Although trauma and preexisting disorders of the arterial wall are the main predisposing factors, most CADs are considered ‘spontaneous’. We hypothesized that CAD could originate in systemic vascular disease bound to the intima–media interface without clinical signs. If this hypothesis is true, endothelium-dependent vasodilation would be impaired in response to a physiological stimulus such as an increase in blood flow. Methods: Flow-mediated arterial dilation was studied in 65 consecutive patients with spontaneous CAD: 26 with carotid artery dissection (ICAD), and 39 with vertebral artery dissection (VAD). CAD patients with vascular risk factors, trivial or obvious cervical trauma, or connective tissue disease were excluded. Twenty-three patients with ischemic stroke of unknown cause were included as controls. Using high-resolution ultrasonography, brachial artery diameter was measured at rest, during post-ischemic hyperemia (flow-mediated endothelium-dependent dilation), and after sublingual glyceryl trinitrate spray (endothelium-independent dilation). Results: The mean ± SD values of the flow-mediated vasodilation index were 5.7 ± 6.2% in ICAD, 5.0 ± 9.3% in VAD and 13.2 ± 6.5% in controls (p < 0.0005), without any difference between ICAD and VAD. Endothelium-independent dilation mean values were 21.5 ± 9.5% in ICAD, 25.1 ± 12.5% in VAD, and 20.8 ± 8.4% in controls, without a significant difference between groups (p = 0.49). Conclusions: These results give evidence of impaired endothelium-dependent vasodilation in CAD patients that is not the result of stroke, and suggest that an underlying abnormality of the arterial wall layers may predispose to CAD.
Hyperdense Middle Cerebral Artery Sign: Can It Be Used to Select Intra-Arterial versus Intravenous Thrombolysis in Acute Ischemic Stroke?
Authors: Agarwal Pinky , Kumar Sanjeev , Hariharan Subramanian , Eshkar Noam , Verro Piero , Cohen Barry , Sen Souvik
Published: December 2003

Background: Stroke patients with a hyperdense middle cerebral artery sign (HMCAS) may respond less favorably to intravenous (IV) thrombolysis. Objective: To compare outcomes of patients with and without early CT findings treated with IV versus intra-arterial (IA) recombinant tissue plasminogen activator (rtPA). Methods: Initial and 24-hour CT scans of the head were evaluated in 83 consecutive stroke patients (66 on IV rtPA, 17 on IA rtPA). Time permitting, a CT angiogram was performed immediately after the initial CT scan to ascertain major cerebral artery occlusion. Demographics and etiological stroke subtype, times to thrombolysis and CT scan, baseline (prethrombolysis) and 24-hour National Institutes of Health stroke scale (NIHSS) score, discharge NIHSS score and 90-day modified Rankin scale (mRS) were recorded. The initial CT of these patients was examined for early signs of stroke. The 24-hour scan was reviewed for the presence of infarct, hemorrhage and persistence of HCMAS. Results: A favorable outcome, indicated by a significant improvement in the discharge NIHSS score, was noted with IA rtPA, irrespective of the presence (p = 0.001) or absence (p = 0.01) of HCMAS. A less favorable outcome in discharge NIHSS score was noted with IV rtPA in patients with HCMAS (p = not significant) than those without the sign (p < 0.001). A similar proportion of patients with HCMAS exhibited a neurological improvement at 24 h as those without the sign in the IA rtPA group (p = 0.9). However, a smaller proportion of patients with HCMAS exhibited a neurological improvement at 24 h than those without the sign in the IV rtPA group (p = 0.005). The results were similar using 90-day mRS ≤1 as an indicator of significant persistent improvement (p = 1.0 for IA rtPA and 0.04 for IV rtPA group). Conclusions: In a small sample, patients with HMCAS appeared to respond better to IA than IV rtPA.
Reconstituted High-Density Lipoprotein Exhibits Neuroprotection in Two Rat Models of Stroke
Authors: Paternò Roberto , Ruocco Antonio , Postiglione Alfredo , Hubsch Alphonse , Andresen Irmgard , Lang Markus G.
Published: December 2003

Background: Reconstituted high-density lipoprotein (rHDL) is prepared from apolipoprotein A-I, isolated from human plasma, and soybean-derived phosphatidylcholine and exhibits biochemical and functional characteristics similar to endogenous nascent high-density lipoprotein (HDL). This study tested the hypothesis that pretreatment with rHDL may reduce neuronal damage in 2 experimental rat models of stroke. Methods: In the first model, an excitotoxic lesion was induced by unilateral injection of N-methyl-D-aspartate (NMDA) in the right striatum (excitotoxic lesion model). In the second model, temporary occlusion of the middle cerebral artery (MCA) was attained by inserting a nylon thread through the carotid artery and blood flow was restored 30 min later (MCAo model). In both models, either rHDL (120 mg/kg) or saline (control) were infused over 4 h, starting 2 h before the injection of NMDA or the induction of ischemia, respectively. 24 h after the interventions, the rats were sacrificed and the brains removed for histochemical preparation. The necrotic area was delimited using an image analysis system. In addition, the levels of reactive oxygen species (ROS) in human endothelial (ECV 304) and neuroblastoma (SK-N-BE) cell lines were measured fluorometrically as 2′,7′-dichlorofluorescein fluorescence in the presence and absence of rHDL and under basal and stress-induced conditions. Results: In the excitotoxic lesion and MCAo models, pretreatment with rHDL significantly reduced the brain necrotic area by 61 and 76%, respectively (p < 0.01). Overnight incubation of ECV 304 and SK-N-BE cells with 0.5 mg/ml rHDL decreased basal and stress-induced ROS levels by 73 and 72% (ECV 304) and by 76 and 43% (SK-N-BE), respectively (p < 0.01). Conclusion: These results suggest that rHDL reduces neuronal damage after onset of ischemic stroke, possibly by involving an anti-oxidative mechanism. Thus, rHDL may be a powerful neuroprotective tool for the treatment of cerebrovascular diseases.
Measurement of Ankle Brachial Index for Assessment of Atherosclerosis in Patients with Stroke
Authors: Nakano Takahiro , Ohkuma Hiroki , Suzuki Shigeharu
Published: December 2003

Background: Though atherosclerosis is generally regarded as a risk factor for stroke, its quantitative assessment in patients with stroke has not yet been reported. Recently, the ankle brachial index (ABI) has been receiving increasing attention as a noninvasive measurement of atherosclerosis. In this study, we investigated ABI to determine the degree of atherosclerosis in patients with stroke. Methods: ABI was measured in 114 patients who had suffered a stroke, and the significance of differences between the ABI of the stroke subgroups and that of the normal group was investigated. The correlation of ABI with the degree of cerebral artery stenosis was also investigated. Results: There was no significant difference in ABI between the hemorrhagic groups and the normal group, but in the infarction group (p = 0.0002) ABI was significantly less than the normal group. ABI was significantly correlated with the degree of stenosis in the intracranial internal carotid artery and middle cerebral artery (p < 0.0001, respectively). Conclusions: A strong relationship between ischemic stroke and atherosclerosis was demonstrated quantitatively by ABI measurement. A decrease in ABI may be a risk factor for ischemic stroke.
Reliability of the Questionnaire for Verifying Stroke-Free Status
Authors: Meschia James F. , Lojacono Marc A. , Miller Mary J. , Brott Thomas G. , Atkinson Elizabeth J. , O’Brien Peter C.
Published: December 2003

Background: The Questionnaire for Verifying Stroke-Free Status (QVSS) is a practical instrument for confirming absence of previous symptomatic stroke or transient ischemic attack in control subjects participating in stroke research. Methods: We tested reliability of telephone administration of the QVSS in stroke patients and healthy volunteers aged ≧50 years. For intrarater reliability, one interviewer administered the QVSS twice to the same subjects 8 weeks apart (115 subjects). For interrater reliability, one interviewer administered the QVSS and a different interviewer readministered the QVSS 8 weeks later (107 subjects). Both interviewer and interviewee were masked to responses from the first interview. Results: Intrarater agreement for overall classification of stroke-free status was 0.90 [95% confidence interval (CI), 0.82–0.94], with a ĸ of 0.78 (95% CI, 0.67–0.90). Interrater agreement for overall classification was 0.94 (95% CI, 0.88–0.98), with a ĸ of 0.89 (95% CI, 0.80–0.97). Conclusion: The QVSS is a reliable instrument for telephone interviews in stroke research when applied to adult populations without severe deficits of cognition or verbal communication.
Glutathione Recycling and Antioxidant Enzyme Activities in Erythrocytes of Term and Preterm Newborns at Birth
Authors: Frosali Simona , Di Simplicio Paolo , Perrone Serafina , Di Giuseppe Danila , Longini Mariangela , Tanganelli Donatella , Buonocore Giuseppe
Published: December 2003

We previously demonstrated a high susceptibility of neonatal red blood cells (RBC) to oxidative stress at birth. The aim of this study was to compare the RBC antioxidant capacity and redox cycle enzyme activities as well as glutathione (GSH) recycling in full-term and preterm infants at birth and in normal adults. GSH and GSH disulfide (GSSG) concentrations, GSH/GSSG ratio, and the activities of glucose-6-phosphate dehydrogenase (G-6-PDH), GSH peroxidase, GSH reductase (GR), catalase (CAT), superoxide dismutase (SOD), and hexokinase (HK) were measured in RBC of 25 healthy adults and 56 newborns (23 term, 33 preterm) at birth. The GSH recycling was measured in adult and newborn RBC exposed to oxidative stress (1 mM tert-butylhydroperoxide). The RBC of term and preterm babies showed higher GSH, GSSG, G-6-PDH, GR, and HK levels/activities and lower GSH/GSSG ratios and higher GSH-recycling rates than those of adults. In preterm babies significant correlations were found between G-6-PDH and CAT, GSH, GSH/GSSG ratio, and GSSG (r = –0.67, r = 0.71, r = –0.66, p < 0.01; r = 0.71, p < 0.05, respectively). In term newborns, statistically significant correlations were observed between G-6-PDH and CAT, SOD, and GSH (r = –0.65, r = –0.65, r = –0.69, p < 0.01, respectively). The results indicate the central role of the G-6-PDH activity in antioxidant defenses. We speculate that preterm babies have prompter involvement of antioxidant defenses than term babies.
Trans- and Retroperitoneal Endoscopic Adrenalectomy: Experience in 26 Consecutive Adrenalectomies
Authors: Giger U. , Vonlanthen R. , Michel J.M. , Krähenbühl L.
Published: December 2003

Objective: To assess our current concept and results of transperitoneal laparoscopic adrenalectomy (TPLA) and retroperitoneal endoscopic adrenalectomy (ERA) for a variety of benign disorders of the adrenal glands. Background Data:According to the literature, minimal invasive adrenalectomy has shown to be a safe and effective surgical alternative to open adrenalectomy. Both, transperitoneal and retroperitoneal endoscopic minimal invasive access are currently used for surgical removal of benign adrenal tumors. There is still some debate about the indications and the access used for a minimal invasive approach. Patients and Methods: Treatment and clinical outcome of all patients who underwent either transperitoneal laparoscopic or endoscopic retroperitoneal adrenalectomies for benign diseases from February 1997 to August 2002 were analyzed retrospectively. Results: Twenty-six minimal invasive adrenalectomies were performed in 23 patients with a mean age of 57 years. Whereas 11 patients underwent unilateral right- sided ERA, unilateral TPLA was performed in 9 patients on the left side. Three patients had bilateral TPLA. The mean operating time for unilateral ERA and TPLA was 114 and 79 min, respectively. Bilateral TPLA was prolonged to 223 min operating time. There were only two minor postoperative complications. The mean hospital stay for unilateral TPLA, ERA and bilateral TPLA was 4.7, 5 and 6 days, respectively. There was no mortality. Conclusion: Both, ERA and TPLA are safe and clinically effective treatment modalities for benign disorders of the adrenal glands. We currently favor a transperitoneal laparoscopic approach for bilateral and left-sided adrenal tumors, whereas right-sided tumors <8 cm are removed by a retroperitoneal approach. Large right-sided tumors >8 cm are better removed by transperitoneal access.
Colonic Involvement in Acute Pancreatitis
Authors: van Minnen L.P. , Besselink M.G.H. , Bosscha K. , van Leeuwen M.S. , Schipper M.E.I. , Gooszen H.G.
Published: December 2003

Background: Diagnosis of colonic pathology complicating acute pancreatitis is difficult. Several pathogenetic mechanisms have been proposed. The treatment of choice is resection of the affected segment. Current theories on diagnosis, pathogenesis, and treatment were reviewed. Method: Retrospectively, 16 patients with severe acute pancreatitis and colonic complications (1988–2001) were included. Preoperative CT scans and specimens of removed colonic segments were reviewed by a blinded radiologist and pathologist respectively. Results: Sixteen patients underwent partial colectomy for suspected imminent or overt perforation, based on the outer aspect of the colon. Four patients had a macroscopic perforation during surgery. Retroperitoneal spread of the necrotizing process to the colon was seen in all 10 reviewed CT scans. All 14 microscopically examined specimens showed fat necrosis and pericolitis. Of these, 4 had ischemia and 6 showed subserosal hemorrhage. Eight specimens had intact mucosa, submucosa and smooth muscle layers. Eleven patients died. Secondary anastomosis in surviving patients did not induce further mortality. Conclusion: Spread of pancreatic enzymes and necrosis is the major cause for colonic pathology in acute pancreatitis. Outside inspection of the colon during surgery is unreliable to detect ischemia or imminent perforation. To prevent colonic complications during follow-up, low-threshold colonic resection seems justified.
Outcomes and Indications of Segmental Pancreatectomy
Authors: Shibata Satoshi , Sato Tsutomu , Andoh Hideaki , Yasui Ouki , Yoshioka Masato , Kurokawa Toshiaki , Watanabe Go , Ise Norihito , Kotanagi Hitoshi , Asanuma Yoshihiro , Koyama Kenji
Published: December 2003

Background/Aim: To preserve pancreatic function, segmental pancreatectomy has been proposed for benign or low-malignancy tumors in the pancreatic body. Indications for the procedure, however, are still controversial. Methods: In this study, we investigated the advantages and disadvantages of segmental pancreatectomy compared with distal pancreatectomy and subsequently determined indications for segmental pancreatectomy. Results: The distal pancreatectomy patients had shorter operation times, lower incidence of operative complications, and shorter hospital stays compared to segmental pancreatectomy patients. Endocrine function in distal pancreatectomy patients deteriorated compared to that of segmental pancreatectomy patients. The postoperative 75-gram oral glucose tolerance test showed a diabetic pattern in 3 of 7 distal pancreatectomy patients, whereas none of the segmental pancreatectomy patients became diabetic after surgery. The relation between the length of the removed pancreas and plasma glucose at 2 h after the 75-gram glucose intake showed a significant correlation. Conclusion: According to our results, if the length of removed pancreas is longer than 12 cm, the patients will have a risk of acquiring diabetes. In those cases, the segmental pancreatectomy should be considered.
Inter-Rater Reliability of the Brazilian Version of the Paykel Scale of Stressful Life Events
Authors: de Oliveira Maria das Graças , Pinto Fonseca Patrícia , Del Porto José Alberto
Published: December 2003

The inter-rater reliability of the Brazilian version of the Recent Life Events Interview, developed by Paykel in order to evaluate stressful life events, was studied in 21 psychiatric inpatients and 20 psychiatric outpatients. Data concerning the agreement between the two raters showed a satisfactory reliability for specific occurrence of events, month of occurrence, independence of events and negative objective impact. This preliminary study suggests that the Brazilian version of the Recent Life Events Interview is a reliable instrument for the assessment of life events in Brazilian samples.
Sleep Disturbances in Somatoform Pain Disorder
Authors: Aigner Martin , Graf André , Freidl Marion , Prause Wolfgang , Weiss Maria , Kaup-Eder Barbara , Saletu Bernd , Bach Michael
Published: December 2003

Patients with chronic somatoform pain often complain about sleep disorders. However, sleep disorder/disturbances are not an integrated part of the somatoform disorders in the DSM-IV and the ICD-10. Sleep is important for recreation. Deprivation of deep sleep stages is experimentally linked to muscle pain. Therefore, sleep disorder may play an important part in the persistence of somatoform pain disorder. The aim of the study was to evaluate the frequency of sleep disorder in patients with somatoform pain disorder and to correlate it with comorbid depression, pain parameters and psychosocial parameters. Method: In this study, 147 patients (mean age: 48.8 years; SD: 11.0) with the diagnosis of a somatoform pain disorder were studied with regard to affective comorbidity, pain duration (months), maximum pain within the last month, minimum pain within the last month and medium pain within the last month, psychosocial disability within the last month and the presence of a sleep disorder. Results: Eighty-four percent of the patients had a sleep disorder. The patients with a sleep disorder had significantly higher maximum and medium pain, a significantly higher level of psychosocial disability and a significantly lower overall subjective well-being. The medium pain and psychosocial disability in leisure and social activities are significant predictors for sleep disorder. Conclusions: The presence of a sleep disorder may be a hint for higher pain intensity and a higher level of psychosocial disability. Sleep disorder may be a factor in the persistence and aggravation of pain as well as psychosocial disability. Therefore, sleep disorder should be integrated in the therapeutic targets. It is suggested that sleep disorder should be a diagnostic criterion in somatoform pain disorder.
Redox Status in Very-Low Birth-Weight Newborns
Authors: Filippi L. , Messeri A. , Dani C. , Pezzati M. , Tronchin M. , Giani T. , Bossoli S. , Rubaltelli F.F.
Published: December 2003

Inborn metabolic diseases, such as disorders in pyruvate metabolism, in gluconeogenesis or in the respiratory chain, may present with lactic acidosis in newborn infants. A simple tool to screen for the efficacy of mitochondrial oxidation reduction activity is the detection of the redox status through simultaneous measurements of plasma lactate, pyruvate and ketone bodies, which are strongly influenced by feeding and stress. We present the redox status values of 55 very-low birth-weight infants under different nutritional conditions. We were able to demonstrate that the redox status values are not dependent on the type of nutrition (oral feeding or continuous enteral nutrition). Instead we observed a strong difference between newborns with intrauterine growth retardation and newborns with appropriate growth. Newborns with intrauterine growth retardation show lower preprandial values of glucose and ketone bodies than newborns with appropriate weight, but higher levels of lactate and pyruvate; nevertheless the lactate/pyruvate and β-hydroxybutyrate/acetoacetate ratios are normal. The results of the redox status study could suggest the reduced activity of gluconeogenesis and, probably, of β-oxidation in very-low birth-weight newborns with intrauterine growth retardation.
Characterization of Two Types of Endothelial Progenitor Cells and Their Different Contributions to Neovasculogenesis
Authors: Hur Jin , Yoon Chang-Hwan , Kim Hyo-Soo , Choi Jin-Ho , Kang Hyun-Jae , Hwang Kyung-Kook , Oh Byung-Hee , Lee Myoung-Mook , Park Young-Bae
Published: December 2003

Objective—

Endothelial progenitor cells (EPC) in one study group is not the same as EPC in other investigators, suggesting that EPC is not a single type of cell population. In this study, we tried to demonstrate the heterogeneity of EPC.

Methods and Results—

We cultured total mononuclear cells from human peripheral blood to get two types of EPC sequentially from the same donors. We called them early EPC and late EPC. Early EPC with spindle shape showed peak growth at 2 to 3 weeks and died at 4 weeks, whereas late EPC with cobblestone shape appeared late at 2 to 3 weeks, showed exponential growth at 4 to 8 weeks, and lived up to 12 weeks. Late EPC was different from early EPC in the expression of VE-cadherin, Flt-1, KDR, and CD45. Late EPC produced more nitric oxide, incorporated more readily into human umbilical vein endothelial cells monolayer, and formed capillary tube better than early EPC. Early EPC secreted angiogenic cytokines (vascular endothelial growth factor, interleukin 8) more so than late EPC during culture in vitro. Both types of EPC showed comparable in vivo vasculogenic capacity.

Conclusions—

We found two types of EPC from a source of adult peripheral blood that might have different roles in neovasculogenesis based on the identified differences.
Betaine as a Determinant of Postmethionine Load Total Plasma Homocysteine Before and After B-Vitamin Supplementation
Authors: Holm Pål I. , Bleie Øyvind , Ueland Per M. , Lien Ernst A. , Refsum Helga , Nordrehaug Jan E. , Nygård Ottar
Published: December 2003

Objective—

Betaine is a substrate in the betaine–homocysteine methyltransferase reaction, converting homocysteine to methionine. There are only sparse data on plasma betaine as a determinant of the plasma total homocysteine (tHcy) concentration.

Methods and Results—

Ninety patients undergoing coronary angiography were randomized into 4 groups administered oral: (1) folic acid (0.8 mg), vitamin B12 (0.4 mg), and vitamin B6 (40 mg); (2) folic acid and vitamin B12; (3) vitamin B6 alone; or (4) placebo. Nonfasting blood samples were collected at baseline and 3, 14, and 28 days and 3, 6, and 12 months after treatment start. A 4-hour methionine-loading test (0.1 g/kg) was performed at baseline and after 3 months. At baseline, median (interquartile range) plasma betaine was 36.9 μmol/L (range: 30.3 to 46.8) and was increased by 15% after methionine loading. The postmethionine load (PML) increase in tHcy was inversely related to plasma betaine (β=−0.29,
P
=0.02) and even more strongly to PML betaine (β=−0.47,
P
<0.001). After 3 months of intervention, the relation between the PML increase in tHcy and PML betaine was weakened (β=−0.33,
P
=0.007).

Conclusions—

Plasma betaine is a strong determinant of the PML increase in tHcy in subjects not supplemented with B-vitamins.
Toll-Like Receptor 4 Is Involved in Outward Arterial Remodeling
Authors: Hollestelle Saskia C.G. , de Vries Margreet R. , van Keulen J. Karlijn , Schoneveld Arjan H. , Vink Aryan , Strijder Chaylendra F. , van Middelaar Ben J. , Pasterkamp Gerard , Quax Paul H.A. , de Kleijn Dominique P.V.
Published: December 2003

Background—

Toll-like receptor 4 (Tlr4) is the receptor for exogenous lipopolysaccharides (LPS). Expression of endogenous Tlr4 ligands, heat shock protein 60 (Hsp60) and extra domain A of fibronectin, has been observed in arthritic and oncological specimens in which matrix turnover is an important feature. In atherosclerosis, outward remodeling is characterized by matrix turnover and a structural change in arterial circumference and is associated with a vulnerable plaque phenotype. Since Tlr4 ligands are expressed during matrix turnover, we hypothesized that Tlr4 is involved in arterial remodeling.

Methods and Results—

In a femoral artery cuff model in the atherosclerotic ApoE3 (Leiden) transgenic mouse, Tlr4 activation by LPS stimulated plaque formation and subsequent outward arterial remodeling. With the use of the same model in wild-type mice, neointima formation and outward remodeling occurred. In Tlr4-deficient mice, however, no outward arterial remodeling was observed independent of neointima formation. Carotid artery ligation in wild-type mice resulted in outward remodeling without neointima formation in the contralateral artery. This was associated with an increase in Tlr4 expression and EDA and Hsp60 mRNA levels. In contrast, outward remodeling was not observed after carotid ligation in Tlr4-deficient mice.

Conclusions—

These findings provide genetic evidence that Tlr4 is involved in outward arterial remodeling, probably through upregulation of Tlr4 and Tlr4 ligands.
Exercise Training Reduces Neointimal Growth and Stabilizes Vascular Lesions Developing After Injury in Apolipoprotein E–Deficient Mice
Authors: Pynn Marianne , Schäfer Katrin , Konstantinides Stavros , Halle Martin
Published: December 2003

Background—

Population-based studies have shown that exercise reduces cardiovascular morbidity and mortality. However, it is unknown whether these effects are solely a result of risk factor modification or whether exercise directly affects the homeostasis of the vessel wall.

Methods and Results—

We subjected 19-week-old apolipoprotein E (apoE)–knockout mice (apoE
−/−
; n=25) to a 6-week training program on a motorized treadmill. The control group consisted of 17 sedentary mice. After 3 weeks in the program, training and sedentary mice underwent carotid artery injury with ferric chloride. Training was then resumed for another 3 weeks. Exercise did not change body weight or lipid levels in apoE
−/−
mice but resulted in upregulated expression of nitric oxide synthase in the endothelium. Physical training did not significantly affect the thrombotic response to injury. However, morphometric analysis of vessels harvested 3 weeks after injury showed that neointima formation was reduced in the exercising group. This resulted in a lower intima/media ratio (0.29±0.03 versus 0.41±0.03 in sedentary mice;
P
=0.008) and less luminal stenosis (21±2.7% versus 33±2.3%;
P
=0.003). Importantly, exercise reduced the number of Mac-3–positive, oxidized LDL-containing macrophages in the vessel wall while increasing the content in collagen fibers (14.1±0.9% versus 4.8±0.8%;
P
<0.001). Plasminogen activator inhibitor-1, tissue factor, and fibrinogen were all significantly reduced in the lesions of trained mice.

Conclusions—

In the apoE
−/−
mouse, exercise training reduces neointimal growth and stabilizes vascular lesions after injury. These effects appear to be at least partly independent of changes in lipid levels or the initial thrombotic response to injury.
Preoperative Partitioning of Pulmonary Vascular Resistance Correlates With Early Outcome After Thromboendarterectomy for Chronic Thromboembolic Pulmonary Hypertension
Authors: Kim Nick H.S. , Fesler Pierre , Channick Richard N. , Knowlton Kirk U. , Ben-Yehuda Ori , Lee Stephen H. , Naeije Robert , Rubin Lewis J.
Published: December 2003

Background—

Pulmonary thromboendarterectomy (PTE) is the preferred treatment for chronic thromboembolic pulmonary hypertension (CTEPH), but persistent pulmonary hypertension after PTE, as a result of either inaccessible distal thrombotic material or coexistent intrinsic small-vessel disease, remains a major determinant of poor outcome. Conventional preoperative evaluation is unreliable in identifying patients at risk for persistent pulmonary hypertension or predicting postoperative hemodynamic outcome. We postulated that pulmonary arterial occlusion pressure waveform analysis, a technique that has been used for partitioning pulmonary vascular resistance, might identify CTEPH patients with significant distal, small-vessel disease.

Methods and Results—

Twenty-six patients underwent preoperative right heart catheterization before PTE. Pulmonary artery occlusion waveform recordings were performed in triplicate. Postoperative hemodynamics after PTE were compared with preoperative partitioning of pulmonary vascular resistance derived from the occlusion data. Preoperative assessment of upstream resistance (R
up
) correlated with both postoperative total pulmonary resistance index (
R
2
=0.79,
P
<0.001) and postoperative mean pulmonary artery pressure (
R
2
=0.75,
P
<0.001). All 4 postoperative deaths occurred in patients with a preoperative R
up
<60%.

Conclusions—

Pulmonary arterial occlusion pressure waveform analysis may identify CTEPH patients at risk for persistent pulmonary hypertension and poor outcome after PTE. Patients with CTEPH and R
up
value <60% appear to be at highest risk.
Kallikrein Gene Transfer Protects Against Ischemic Stroke by Promoting Glial Cell Migration and Inhibiting Apoptosis
Authors: Xia Chun-Fang , Yin Hang , Borlongan Cesar V. , Chao Lee , Chao Julie
Published: December 2003

Kallikrein/kinin has been shown to protect against ischemia/reperfusion-induced myocardial infarction and apoptosis. In the present study, we examined the potential neuroprotective action of kallikrein gene transfer in cerebral ischemia. Adult, male Sprague-Dawley rats were subjected to a 1-hour occlusion of the middle cerebral artery followed by intracerebroventricular injection of adenovirus harboring either the human tissue kallikrein gene or the luciferase gene. Kallikrein gene transfer significantly reduced ischemia-induced locomotor deficit scores and cerebral infarction after cerebral ischemia injury. Expression of recombinant human tissue kallikrein was identified and localized in monocytes/macrophages of rat ischemic brain by double immunostaining. Morphological analyses showed that kallikrein gene transfer enhanced the survival and migration of glial cells into the ischemic penumbra and core, as identified by immunostaining with glial fibrillary acidic protein. Cerebral ischemia markedly increased apoptotic cells, and kallikrein gene delivery reduced apoptosis to near-normal levels as seen in sham control rats. In primary cultured glial cells, kinin stimulated cell migration but inhibited hypoxia/reoxygenation-induced apoptosis in a dose-dependent manner. The effects of kinin on both migration and apoptosis were abolished by icatibant, a bradykinin B
2
receptor antagonist. Enhanced cell survival after kallikrein gene transfer occurred in conjunction with markedly increased cerebral nitric oxide levels and phospho-Akt and Bcl-2 levels but reduced caspase-3 activation, NAD(P)H oxidase activity, and superoxide production. These results indicate that kallikrein gene transfer provides neuroprotection against cerebral ischemia injury by enhancing glial cell survival and migration and inhibiting apoptosis through suppression of oxidative stress and activation of the Akt–Bcl-2 signaling pathway.
Evidence for a Causal Role of the Renin-Angiotensin System in Vascular Dysfunction Associated With Insulin Resistance
Authors: Shinozaki Kazuya , Ayajiki Kazuhide , Nishio Yoshihiko , Sugaya Takeshi , Kashiwagi Atsunori , Okamura Tomio
Published: December 2003

Excess production of superoxide anion in response to angiotensin II plays a central role in the transduction of signal molecules and the regulation of vascular tone. We examined the ability of insulin resistance to stimulate superoxide anion production and investigated the identity of the oxidases responsible for its production. Rats were fed diets containing 60% fructose (fructose-fed rats) or 60% starch (control rats) for 8 weeks. In aortic homogenates from fructose-fed rats, the superoxide anion generated in response to NAD(P)H was more than 2-fold higher than that of control rats. Pretreatment of the aorta from fructose-fed rats with inhibitors of NADPH oxidase significantly reduced superoxide anion production. In the isolated aorta, contraction induced by angiotensin II was more potent in fructose-fed rats compared with control rats. Losartan normalized blood pressure, NAD(P)H oxidase activity, endothelial function, and angiotensin II-induced vasoconstriction in fructose-fed rats. To elucidate the molecular mechanisms of the enhanced constrictor response to angiotensin II, expressions of angiotensin II receptor and subunits of NADPH oxidase were examined with the use of angiotensin II type 1a receptor knockout (AT1a KO) mice. Expression of AT1a receptor mRNA was enhanced in fructose-fed mice, whereas expression of either AT1b or AT2 was unaltered. In addition, protein expression of each subunit of NADPH oxidase was increased in fructose-fed mice, whereas the expression was significantly decreased in fructose-fed AT1a KO mice. The novel observation of insulin resistance-induced upregulation of AT1 receptor expression could explain the association of insulin resistance with endothelial dysfunction and hypertension.
Nitric Oxide Synthesis Inhibition Promotes Renal Production of Carbon Monoxide
Authors: Rodriguez Francisca , Lamon Brian D. , Gong Weiying , Kemp Rowena , Nasjletti Alberto
Published: December 2003

We tested the hypothesis that the status of NO synthesis influences the renal heme-heme oxygenase system. Studies were conducted in untreated rats and rats treated with the NO synthesis inhibitor
N
G
-nitro-
l
-arginine methyl ester for 2 days. Treated and untreated rats were contrasted in terms of renal expression of heme oxygenase-1 and -2, renal carbon monoxide (CO)-generating activity, and urinary CO concentration and excretion rate. Heme oxygenase-1 and -2 proteins were similarly expressed in the kidneys of untreated and treated rats. In contrast, the NADPH-dependent component of the CO-generating activity of renal homogenates incubated with heme (a measure of heme oxygenase activity) was higher (
P
<0.05) in kidneys from rats treated with the NO synthesis inhibitor relative to corresponding data in untreated rats (1015±95 versus 379±111 pmol CO/mg per hour). Similarly, relative to corresponding data in untreated rats, rats treated with the NO synthesis inhibitor displayed increased (
P
<0.05) urinary CO concentration (920±174 versus 2286±472 pmol/mL) and urinary CO excretion (4.7±0.4 versus 14.3±2.7 pmol/min). This study demonstrates that NO synthesis inhibition upregulates the urinary concentration and excretion rate of CO, and the HO-dependent generation of CO by renal homogenates, without affecting the expression of renal heme oxygenase isoforms. Our findings imply that endogenous NO is an inhibitory regulator of renal CO generation by HO.