bluuebunny/crossref_metadata_2025 huggingface dataset:
Density, habitat use and behaviour of the weedy seadragon Phyllopteryx taeniolatus (Teleostei:Syngnathidae) around Sydney, New South Wales, Australia
Authors: Sanchez-Camara Jaime , Booth David J. , Murdoch John , Watts David , Turon Xavier
Published: October 2006

The vulnerability of marine fish species, particularly those inhabiting coastal waters, is an increasingly important issue in marine conservation. Although the weedy seadragon Phyllopteryx taeniolatus (Lacepede, 1804), a syngnathid fish endemic to southern Australia, is legally protected in New South Wales, there are no studies on population density, habitat use and behaviour to support this protection. We investigated the abundance, sex ratios and distribution of the weedy seadragon at three sites near Sydney, Australia. The distribution, density and sex ratios of seadragons were temporally stable, suggesting no large-scale seasonal migrations. Estimated population densities varied among sites from 10 individuals per ha to 65 individuals per ha, with sex ratios close to 1 : 1. Survival rates from one encounter to the next (approximately weekly) were high, being slightly lower for males (0.985 ± 0.006, mean ± se) and females (0.987 ± 0.005) compared with juveniles (1.000 ± 0.000). All size classes and both sexes were most common near the border of kelp and sand except when exhibiting hiding behaviour, when they were more often found in kelp beds. Kelp beds were the least-used habitat when feeding. Pregnant males tended to hide more often than other groups and therefore were more frequently found in kelp and kelp patches. Seadragons tended to be solitary, although pairing and grouping behaviour was also observed. Results of the present study show that weedy seadragons are resident in the same area throughout the year and have a strong affinity with heavily weeded rock and/or sand habitat. It is therefore recommended that the current species-based protection laws be used in concert with habitat-protection zones as a necessary measure to ensure the conservation of weedy seadragon populations.
Regional and local species diversity patterns for lotic invertebrates across multiple drainage basins in Victoria
Authors: Marchant R. , Ryan D. , Metzeling L.
Published: October 2006

Regional (RSR) and local species richness (LSR) was recorded for stream invertebrate communities at reference sites in 25 drainage basins in Victoria. Regional species richness was defined as the total number of species recorded at all reference sites within a basin, and LSR as the total numbers of species recorded at a single reference site. Records were obtained from bank and channel habitats and analysed separately. Regressions between LSR and RSR indicated a proportional or linear relationship in both habitats. This applied to the whole data set and to subgroups representing Ephemeroptera, Plecoptera and Trichoptera (EPT as a group), Hemiptera, Diptera, and Coleoptera. All data sets thus represented communities in which no upper limit to LSR was observed. Multiple regressions between LSR and RSR, number of samples per site (N) and seven physical variables showed that RSR and N were nearly always significantly related to LSR. Few of the physical variables were significant except conductivity (for EPT and Coleoptera). Multidimensional scaling ordinations revealed an east-west gradient in compositional similarity of invertebrates, upon which variations in RSR had a major influence. Investigation of factors that regulate RSR will thus be necessary for a broad scale view of what regulates LSR.
Direct magnetic resonance detection of neuronal electrical activity
Authors: Petridou Natalia , Plenz Dietmar , Silva Afonso C. , Loew Murray , Bodurka Jerzy , Bandettini Peter A.
Published: October 2006

Present noninvasive neuroimaging methods measure neuronal activity indirectly, via either cerebrovascular changes or extracranial measurements of electrical/magnetic signals. Recent studies have shown evidence that MRI may be used to directly and noninvasively map electrical activity associated with human brain activation, but results are inconclusive. Here, we show that MRI can detect cortical electrical activity directly. We use organotypic rat-brain cultures
in vitro
that are spontaneously active in the absence of a cerebrovascular system. Single-voxel magnetic resonance (MR) measurements obtained at 7 T were highly correlated with multisite extracellular local field potential recordings of the same cultures before and after blockade of neuronal activity with tetrodotoxin. Similarly, for MR images obtained at 3 T, the MR signal changed solely in voxels containing the culture, thus allowing the spatial localization of the active neuronal tissue.
Serum calcium is an independent predictor of quality of life in multiple myeloma
Authors: Wisløff Finn , Kvam Ann Kristin , Hjorth Martin , Lenhoff Stig
Published: October 2006

Bone disease is an important feature of multiple myeloma, and hypercalcaemia is a frequent complication of this disease. We examined the association between serum calcium and quality of life (QOL) scores of 686 multiple myeloma patients at the time of diagnosis. Data from two Nordic studies using the EORTC QLQ‐C30 questionnaire were analysed by means of linear regression analysis and a curve fitting program. Serum calcium was independently related to appetite loss, nausea/vomiting and physical functioning (P < 0.001) and to cognitive functioning (P = 0.001), i.e. scores reflecting symptoms that are well known in non‐malignant hypercalcaemia. In addition, we found a highly significant independent relationship between serum calcium and the scores for fatigue and pain (P < 0.001). Serum calcium appeared to be as strong a predictor for fatigue as the concentration of haemoglobin. A cubic model (y = a + bx3) fitted the data slightly better than the simple linear model (y = a + bx) and suggested worsening QOL scores at levels of serum calcium above 2.5–3.0 mmol/L. Hypercalcaemia in patients with multiple myeloma seems to be associated with the same symptoms as in non‐malignant hypercalcaemia. In addition, an increased level of serum calcium may aggravate the pain and fatigue caused by the skeletal disease itself.
Decremental Ramp Atrial Extrastimuli Pacing Protocol for the Induction of Atrioventricular Nodal Re‐entrant Tachycardia and Other Supraventricular Tachycardias
Authors: KANTHARIA BHARAT K. , PADDER FAROOQ A. , KUTALEK STEVEN P.
Published: October 2006

Aim: The primary aim of this study was to evaluate the utility of decremental ramp atrial extrastimuli pacing protocol (PRTCL) for induction of atrioventricular nodal re‐entrant tachycardia (AVNRT), and other supraventricular tachycardias (SVTs), compared to standard (STD) methods.

Methods: The study cohort of 121 patients (age 57.51 ± 14.02 years) who presented with documented SVTs and/or symptoms of palpitations and dizziness, and underwent invasive electrophysiological evaluation was divided into Group I (AVNRT, n = 42) and Group II (Control, n = 79). The PRTCL involved a train of six atrial extrastimuli, delivered in a decremental ramp fashion. The STD methods included continuous burst and rapid incremental pacing up to atrioventricular (AV) block cycle length, and single and occasionally double atrial extrastimuli. Prolongation in the Atrio‐Hisian (Δ‐AH) intervals achieved by both methods were compared, as were induction frequencies.

Results: In Group I, three categories of responses—(1) induction of AVNRT, (2) induction of echo beats only, and (3) none—were observed in 29 (69%), 11 (26%), and 2 (5%) patients with the PRTCL, when compared with 14 (33%), 16 (38%), and 12 (29%) patients with STD methods in the baseline state without the use of pharmacological agents. The Δ‐AH intervals for each of these three categories were larger using PRTCL versus STD methods; 293.3 ± 95.2 ms versus 192.9 ± 61.4 ms (P < 0.005), 308.6 ± 68.5 ms versus 189. 9 ± 64.9 ms (P < 0.0005), and 203.0 ± 86.3 ms versus 145.8 ± 58.9 ms (P = NS), respectively. In Group II, in one patient with dual AV nodal physiology but no clinical tachycardia, the PRTCL induced nonsustained (12 beats) AVNRT. Additionally, in this group, both PRTCL and STD methods induced atrial tachycardia in two patients and orthodromic AV re‐entrant tachycardia in one patient.

Conclusion: Decremental ramp atrial extrastimuli pacing PRTCL demonstrates a superior response for induction of typical AVNRT as compared to STD techniques. Because of easy and reliable induction of AVNRT and echo beats by the PRTCL, we recommend it as a method to increase the likelihood of induction of AVNRT. For induction of other SVTs, the PRTCL and the STD methods are comparable.
Brugada Syndrome
Authors: ANTZELEVITCH CHARLES
Published: October 2006

First introduced as a new clinical entity in 1992, the Brugada syndrome is associated with a relatively high risk of sudden death in young adults, and occasionally in children and infants. Recent years have witnessed a striking proliferation of papers dealing with the clinical and basic aspects of the disease. Characterized by a coved‐type ST‐segment elevation in the right precordial leads of the electrocardiogram (ECG), the Brugada syndrome has a genetic basis that thus far has been linked only to mutations in SCN5A, the gene that encodes the α‐subunit of the sodium channel. The Brugada ECG is often concealed, but can be unmasked or modulated by a number of drugs and pathophysiological states including sodium channel blockers, a febrile state, vagotonic agents, tricyclic antidepressants, as well as cocaine and propranolol intoxication. Average age at the time of initial diagnosis or sudden death is 40 ± 22, with the youngest patient diagnosed at 2 days of age and the oldest at 84 years. This review provides an overview of the clinical, genetic, molecular, and cellular aspects of the Brugada syndrome, incorporating the results of two recent consensus conferences. Controversies with regard to risk stratification and newly proposed pharmacologic strategies are discussed.
Acute Subclavian or Axillary Vein Occlusion During Biventricular Pacemaker Implantation
Authors: BREULS NICO P. , RES JAN C. J.
Published: October 2006

During biventricular pacemaker implantation, multiple punctures of the subclavian vein were performed and venous occlusion was apparent during the procedure, which in one case was stopped before lead insertion and in the other patient new access has to be forced through the occlusion by removing one of the already implanted leads. For implanting physicians, it is important to know that acute venous occlusion may occur during lead implantation.
Isolated Giant Cell Myocarditis in the Atrium: An Incidental Finding?
Authors: AHMAD IMRAN , CRAIG MILLER D. , BERRY GERALD J. , HSIA HENRY H. , WANG PAUL J. , AL‐AHMAD AMIN
Published: October 2006

Giant cell myocarditis (GCM) is an uncommon disorder that affects ventricular myocardium causing severe left ventricular dysfunction and ventricular arrhythmias. We report a case of GCM that only affected the atrium sparing the ventricle.
The oral ecosystem: implications for education
Authors: Eriksen H. M. , Dimitrov V. , Rohlin M. , Petersson K. , Svensäter G.
Published: October 2006

Abstract  We propose a model that is applicable to oral health education. The model describes the oral cavity in a complexity‐based ecological context. This concept includes the premise that factors from different organisational levels (biological, individual, community, society) interact in a complex way with the potential to ‘stress’ the ecosystem and thereby provoke changes. This mode of action complies with the understanding of the oral cavity as a complex adaptive system. An ecological model is actively used in the undergraduate problem‐based curriculum at the Faculty of Odontology, Malmö University, Sweden and has recently been applied as a conceptual basis for the new dental curriculum being established at the University of Tromsø in Northern Norway. The purpose is to encourage and promote an ecological, health‐oriented view and to stimulate reflections on premises for oral health and diseases in an integrated context.
Tutor perceptions of the use of a reflective portfolio within a pastoral tutor system to facilitate undergraduate personal development planning
Authors: Ellis J. S. , Hobson R. S. , Waterhouse P. J. , Meechan J. G. , Hogg S. D. , Whitworth J. M. , Thomason J. M.
Published: October 2006

Abstract  All Higher Education Institutions in the UK are now required to provide transcripts of student activity and outcomes of summative assessments. In addition, the student should be able to reflect on their learning and plan their own development. This article reports on the staff evaluation of the use of a reflective portfolio facilitating the production of highly individualised personal development plans within an existing tutor system. A number of significant issues are highlighted; tutor systems adopting this approach must maintain flexibility for managing student crises when they arise, the difference between appraisal and assessment needs clear definition for both students and tutors, training in basic mentoring skills should be provided for all tutors, tutors should be aware of the difficulties many students experience with reflection and also be alert to the over reflective learner.
Handball injuries during major international tournaments
Authors: Langevoort G. , Myklebust G. , Dvorak J. , Junge A.
Published: October 2006

Background: Several authors have analyzed the incidence of handball injuries in amateur players but information of handball injury in top‐level players is very limited. The aim of the study was to analyze the incidence, circumstances and characteristics of handball injuries during major international tournaments.

Methods: Injuries during six international handball tournaments were analyzed, using an established injury report system. The physicians of all participating teams were asked to report all injuries after each match on a standardized injury report form. The response rate was on average 87%.

Results: The incidence of injury was on average 108 injuries/1000 player hours (95% confidence interval (CI): 98–117) or 1.5 injuries/match (95% CI: 1.4–1.6). The injuries affected most frequently the lower extremity (42%), followed by injuries of the head (23%), upper extremity (18%) and trunk (14%). The most frequent diagnosis was contusion of head (14%) or ankle sprain (8%). The majority of injuries were caused by contact with another player. The incidence of time loss injuries was on average 27/1000 player hours (95% CI: 22–32), and significantly higher in men than in women.

Conclusion: Preventive program proven effective should be implemented. Fair Play is an essential aspect of injury prevention. Therefore, close cooperation with the referees is also necessary to make handball a safer sport.
MICROBIOLOGICAL QUALITY OF HAWAWSHY CONSUMED IN ISMAILIA, EGYPT
Authors: ISMAIL SOAD AHMED
Published: October 2006

The focus of this study was to evaluate the microbial quality of hawawshy from vending shops in Ismailia Province, Egypt. Microbiological analysis of hawawshy resulted in aerobic plate counts from 2 × 103 to 4 × 106 cfu/g and spore counts from 2 × 102 to 5 × 104 cfu/g. Total coliforms ranged from 3 to 2400 MPN/g while Enterobacteriaceae counts ranged from 6 × 10 to 8 × 102 cfu/g and enterococci counts were 3 × 103 to 6 × 105 cfu/g. Escherichia coli, coagulase positive staphylococci and fecal streptococci were detected in 17.3, 14.6 and 57.3% of examined samples, respectively. Salmonella spp. was not detected. Different Enterobacteriaceae spp. such as Citrobacter freundi, Enterobacter cloacae, Klebsiella oxytoca, Klebsiella pneumoniae and Serratia liquefaciens were isolated with different percentages. The obtained results indicate that consumption of hawawshy may constitute a public health hazard, and as a consequence, handling practices should require more attention and improvement.
CONSUMER ASSESSMENT OF THE SAFETY OF RESTAURANTS: THE ROLE OF INSPECTION NOTICES AND OTHER INFORMATION CUES
Authors: HENSON SPENCER , MAJOWICZ SHANNON , MASAKURE OLIVER , SOCKETT PAUL , JONES ANDRIA , HART ROBERT , CARR DEBORAH , KNOWLES LEWINDA
Published: October 2006

This paper explores the ways in which consumers assess the safety of food in restaurants and other eating‐out establishments, and the resulting impact on restaurant choice. The analysis builds on the existing literature on restaurant choice more generally and a growing body of studies on the impact of official inspection information on the perceived safety of restaurants. Based on a two‐stage consumer study in the City of Hamilton in Ontario, Canada, involving focus groups and a postal survey, the research highlights how consumers base their assessment of food safety in restaurants using a range of visible indicators of the experience and/or credence characteristics associated with foodborne illness. These include their observed judgments of restaurant hygiene, the overall quality of the restaurant, external information, including official inspection certificates, and the level of patronage. The use of these broad groups of indicators varies across consumer subgroups according to gender, age, level of education and recollections of past incidences when a restaurant was closed and/or convicted for food safety reasons.
EVIDENCE OF CROSS‐CONTAMINATION OF AEROMONAS HYDROPHILA BY FINGERPRINTING: SIGNIFICANCE FOR FOOD SAFETY
Authors: GUNSALAM JURIN WOLMON , RADU SON , BENJAMIN PATRICK GUDA , SELAMAT JINAP , ROBIN TUNUNG
Published: October 2006

The prevalence of Aeromonas hydrophila in a local wet market was studied and fingerprinting was used to prove the cross‐contamination. This study describes the use of antibiotic‐resistant plasmid profiles and random amplified polymorphic DNA (RAPD) assay to characterize strains of A. hydrophila. Almost all strains had multiple antibiotic resistances and carried small plasmid(s) of 1.4–6.0 MDa that enabled the A. hydrophila to be grouped into eight plasmid patterns. The RAPD‐polymerase chain reaction profiles observed after electrophoretic separation of the amplified products using primer GEN15007, which enable the A. hydrophila strains to be grouped into three clusters, demonstrate that the A. hydrophila strains were genetically heterogeneous. These results suggest that RAPD assay could be a valuable tool for epidemiological studies. In addition, antibiotic‐resistant and plasmid profiling can also be used as adjunct tools in this study.
Cardiovascular haemodynamics and ventriculo‐arterial coupling in an acute pig model of coronary ischaemia–reperfusion
Authors: Lanoye Lieve , Segers Patrick , Tchana‐Sato Vincent , Rolin Stephanie , Dogne Jean‐Michel , Ghuysen Alexandre , Lambermont Bernard , Hanson Julien , Desaive Thomas , Verdonck Pascal , D'Orio Vincent , Kolh Philippe
Published: October 2006

Although reperfusion after coronary occlusion is mandatory for myocardial salvage, reperfusion may trigger a cascade of harmful events (reperfusion injury) adding to myocardial injury. We investigated effects of reperfusion on left ventricular (LV) haemodynamics and ventriculo‐arterial (VA) coupling in pigs following acute myocardial ischaemia induced by coronary artery occlusion. Experiments were performed in six animals, with measurements of cardiac and arterial function at baseline, after 60 min of ischaemia (T60) and after 2 (T180) and 4 h of reperfusion (T300). Ventriculo‐arterial coupling was assessed using the ventriculo‐arterial elastance ratio of paper, as well as using a ‘stiffness coupling’ and ‘temporal coupling’ index. Reperfusion following ischaemia (T180 versus T60) induced a progressive decline in cardiovascular function, evidenced by a decrease in mean arterial blood pressure, cardiac output and ejection fraction which was not restored at T300. Although reperfusion also induced an increase in slope of the end‐systolic pressure–volume relationship (ESPVR), the ESPVR curve shifted to the right, associated with a depression of contractile function. Histology demonstrated irreversible myocardial damage at T300. The ventriculo‐arterial elastance ratio and the ‘stiffness coupling’ index were unaffected throughout the protocol, but the ‘temporal coupling’ parameter indicated a relative shift between heart period and the time constant of the arterial system. It is unlikely that these alterations are attributable to ischaemic injury alone. The combination of both the stiffness and temporal coupling index may provide more information when studying ventriculo‐arterial coupling than the more commonly used ventricular end‐systolic stiffness/effection arterial elastance (Ees/Ea) ratio.
Myoglobin translational diffusion in rat myocardium and its implication on intracellular oxygen transport
Authors: Lin Ping‐Chang , Kreutzer Ulrike , Jue Thomas
Published: October 2006

Current theory of respiratory control invokes a role of myoglobin (Mb)‐facilitated O2 diffusion in regulating the intracellular O2 flux, provided Mb diffusion can compete effectively with free O2 diffusion. Pulsed‐field gradient NMR methods have now followed gradient‐dependent changes in the distinct 1H NMR γ CH3 Val E11 signal of MbO2 in perfused rat myocardium to obtain the endogenous Mb translational diffusion coefficient (DMb) of 4.24 × 10−7 cm2 s−1 at 22°C. The DMb matches precisely the value predicted by in vivo NMR rotational diffusion measurements of Mb and shows no orientation preference. Given values in the literature for the Krogh's free O2 diffusion coefficient (K0), myocardial Mb concentration and a partial pressure of O2 that half saturates Mb (P50), the analysis yields an equipoise diffusion P of 1.77 mmHg, where Mb and free O2 contribute equally to the O2 flux. In the myocardium, Mb‐facilitated O2 diffusion contributes increasingly more than free O2 diffusion when the P falls below 1.77 mmHg. In skeletal muscle, the P must fall below 5.72 mmHg. Altering the Mb P50 induces modest change. Mb‐facilitated diffusion has a higher poise in skeletal muscle than in myocardium. Because the basal P hovers around 10 mmHg, Mb does not have a predominant role in facilitating O2 transport in myocardium but contributes significantly only when cellular oxygen falls below the equipoise diffusion P.
Mechanosensitive currents in the neurites of cultured mouse sensory neurones
Authors: Hu Jing , Lewin Gary R.
Published: October 2006

Almost all sensory neurones in the dorsal root ganglia have a mechanosensory function. The transduction of mechanical stimuli in vivo takes place exclusively at the sensory ending. For cutaneous sensory receptors it has so far proved impossible to directly record the mechanically gated receptor potential because of the small size and inaccessibility of the sensory ending. Here we investigate whether mechanosensitive currents are present in the neurites of freshly isolated adult mouse sensory neurones in culture. Amost all sensory neurone neurites possess currents gated by submicrometre displacement stimuli (92%). Three types of mechanically activated conductance were characterized based on different inactivation kinetics. A rapidly adapting conductance was found in larger sensory neurones with narrow action potentials characteristic of mechanoreceptors. Slowly and intermediate adapting conductances were found exclusively in putative nociceptive neurones. Mechanically activated currents with similar kinetics were found also after stimulating the cell soma. However, soma currents were only observed in around 60% of cells tested and the displacement threshold was several times larger than for the neurite (∼6 μm). The reversal potential of the rapidly adapting current indicated that this current is largely selective for sodium ions whereas the slowly adapting current is non‐selective. It is likely that distinct ion channel entities underlie these two currents. In summary, our data suggest that the high sensitivity and robustness of mechanically gated currents in the sensory neurite make this a useful in vitro model for the mechanosensitive sensory endings in vivo.
Reduced nicotinic receptor function in sympathetic ganglia is responsible for the hypothermia in the acetylcholinesterase knockout mouse
Authors: Sun Minjeong , Lee C. Justin , Shin Hee‐Sup
Published: October 2006

Cholinergic signalling in the sympathetic ganglia (SG) contributes to non‐shivering thermogenesis by relaying the activation signal from the brain to SG neurons which activate many peripheral tissues to produce heat. Paradoxically, acetylcholinesterase (AChE) inhibitors, which should enhance cholinergic signalling, induce hypothermia. To understand the mechanism of how cholinergic signalling in the SG controls thermoregulation, we analysed infant AChE knockout mice, which are known to show hypothermia by postnatal day 15. Nicotinic receptor currents were reduced in acutely dissociated SG neurons of the AChE‐deficient mice by over 40% compared with wild‐type mice. When wild‐type neurons were treated for 1 h with either oxotremorine‐M, a muscarinic agonist, or nicotine, the amplitude of nicotinic receptor currents was also decreased by 40%. The hypothermia in AChE mutant mice was fully rescued by a peripheral injection of both ivermectin, which increases nicotinic receptor currents, and methyl‐atropine, a muscarinic antagonist. Our results demonstrate that the hypothermia induced by the lack of AChE activity is primarily caused by a downregulation of nicotinic receptors via prolonged stimulation of muscarinic and nicotinic receptors in SG neurons. The stationary noise analysis of the nicotinic receptor current traces showed that the properties of single‐channel activities were not different between the two genotypes, suggesting that the primary reason for downregulation of nicotinic receptors is due to a reduction of the receptors on the surface.
NON-ABELIAN TENSOR GAUGE FIELDS I
Authors: SAVVIDY GEORGE
Published: October 2006

We suggest an infinite-dimensional extension of gauge transformations which includes non-Abelian tensor gauge fields. In this extension of the Yang–Mills theory the vector gauge boson becomes a member of a bigger family of gauge bosons of arbitrarily large integer spins. The invariant Lagrangian does not contain higher derivatives of tensor gauge fields and all interactions take place through three- and four-particle exchanges with dimensionless coupling constant.
Azoxymethane protects intestinal stem cells and reduces crypt epithelial mitosis through a COX-1-dependent mechanism
Authors: Riehl Terrence E. , George Robert J. , Sturmoski Mark A. , May Randal , Dieckgraefe Brian , Anant Shrikant , Houchen Courtney W.
Published: October 2006

Azoxymethane (AOM) is a potent DNA-damaging agent and carcinogen that induces intestinal and colonic tumors in rodents. Evaluation of the stem cell population by colony formation assay reveals that, within 8 h after treatment, AOM (10 mg/kg) elicited a prosurvival response. In wild-type (WT) mice, AOM treatment induced a 2.5-fold increase in intestinal crypt stem cell survival. AOM treatment increased stem cell survival in cyclooxygenase (COX)-2−/− but not COX-1−/− mice, confirming a role of COX-1 in the AOM-induced increase in stem cell survival. COX-1 mRNA and protein expression as well as COX-1-derived PGE2 synthesis were increased 8 h after AOM treatment. Immunohistochemical staining of COX-1 demonstrated expression of the enzyme in the crypt epithelial cells, especially in the columnar epithelial cells between the Paneth cells adjacent to the stem cell zone. WT mice receiving AOM exhibited increased intestinal apoptosis and a simultaneous reduction in crypt mitotic figures within 8 h of injection. There were no significant differences in baseline or AOM-induced intestinal epithelial apoptosis between WT and COX-1−/− mice, but there was a complete reversal of the AOM-mediated reduction in mitosis in COX-1−/− mice. This suggests that COX-1-derived PGE2 may play a key role in the early phase of intestinal tumorigenesis in response to DNA damage and suggests that COX-1 may be a potential therapeutic target in this model of colon cancer.
Nitric oxide impairs baroreflex gain during acute psychological stress
Authors: Daubert Daisy L. , Brooks Virginia L.
Published: October 2006

Psychological stress can suppress baroreflex function, but the mechanism has not been fully elucidated. Nitric oxide in the brain and in the adrenal cortex, as well as plasma glucocorticoids, increases during stress and has been shown to suppress reflex gain in unstressed animals. Therefore, the purpose of this study was to test the hypothesis that stress, caused by exposure to a novel environment, decreases baroreflex gain in rabbits through the actions of nitric oxide to increase corticosterone release. Baroreflex control of heart rate and plasma corticosterone levels was quantified before and after blockade of nitric oxide synthase (NOS) with Nω-nitro-l-arginine (l-NNA; 20 mg/kg iv) in conscious rabbits exposed to a novel environment and in the same rabbits once they had been conditioned to the environment. Stress significantly reduced baroreflex gain from −23.4 ± 2 to −12.2 ± 1.6 beats·min−1·mmHg−1 ( P < 0.05) and increased plasma corticosterone levels from 5.4 ± 0.7 to 15.5 ± 5.0 ng/ml ( P < 0.05). NOS blockade increased gain in stressed animals (to −27.2 ± 5.4 beats·min−1·mmHg−1, P < 0.05) but did not alter gain in unstressed rabbits (−26.8 ± 4.9 beats·min−1·mmHg−1) such that gain was equalized between the two states. NOS blockade increased plasma corticosterone levels in unstressed animals (to 14.3 ± 2.1 ng/ml, P < 0.05) but failed to significantly alter levels in stressed rabbits (14.0 ± 3.9 ng/ml). In conclusion, psychological stress may act via nitric oxide, independently of increases in corticosterone, to decrease baroreflex gain.
Imaging of the pulmonary circulation in the closed-chest rat using synchrotron radiation microangiography
Authors: Schwenke Daryl O. , Pearson James T. , Umetani Keiji , Kangawa Kenji , Shirai Mikiyasu
Published: October 2006

Structural changes of the pulmonary circulation during the pathogenesis of pulmonary arterial hypertension remain to be fully elucidated. Although angiography has been used for visualizing the pulmonary circulation, conventional angiography systems have considerable limitations for visualizing small microvessels (diameters < 200 μm), particularly within a closed-chest animal model. In this study we assess the effectiveness of monochromatic synchrotron radiation (SR) for microangiography of the pulmonary circulation in the intact-chest rat. Male adult Sprague-Dawley rats were anesthetized, and a catheter was positioned within the right ventricle, for administering iodinated contrast agent (Iomeron 350). Subsequently, microangiography of pulmonary arterial branches within the left lung was performed using monochromatic SR. Additionally, we assessed dynamic changes in vessel diameter during acute hypoxic (10% and 8% O2 for 4 min each) pulmonary vasoconstriction (HPV). Using SR we were able to visualize pulmonary microvessels with a diameter of <100 μm (the 4th generation of branching from the left axial artery). Acute hypoxia caused a significant decrease in the diameter of all vessels less than 500 μm. The greatest degree of pulmonary vasoconstriction was observed in vessels with a diameter between 200 and 300 μm. These results demonstrate the effectiveness of SR for visualizing pulmonary vessels in a closed-chest rat model and for assessing dynamic changes associated with HPV. More importantly, these observations implicate SR as an effective tool in future research for assessing gross structural changes associated with the pathogenesis of pulmonary arterial hypertension.
Macrophage Low-Density Lipoprotein Receptor-Related Protein Deficiency Enhances Atherosclerosis in ApoE/LDLR Double Knockout Mice
Authors: Hu L. , Boesten L.S.M. , May P. , Herz J. , Bovenschen N. , Huisman M.V. , Berbée J.F.P. , Havekes L.M. , van Vlijmen B.J.M. , Tamsma J.T.
Published: October 2006

Objective—

In vitro studies implicate that the low-density lipoprotein receptor (LDLR)-related protein (LRP) in macrophages has a pro-atherogenic potential. In the present study, we investigated the in vivo role of macrophage specific LRP in atherogenesis independent of its role in the uptake of lipoproteins.

Methods and Results—

We generated macrophage-specific LRP-deficient mice on an apoE/LDLR double-deficient background. Macrophage LRP deletion did not affect plasma cholesterol and triglyceride levels, lipoprotein distribution, and blood monocyte counts. Nevertheless, macrophage LRP deficiency resulted in a 1.8-fold increase in total atherosclerotic lesion area in the aortic root of 18-week-old mice. Moreover, LRP deficiency also resulted in a relatively higher number of advanced lesions. Whereas macrophage and smooth muscle cell content did not differ between LRP-deficient mice and control littermates, a 1.7-fold increase in collagen content and 2.3-fold decrease in relative number of CD3+ T cells were observed in lesions from macrophage specific LRP-deficient mice.

Conclusions—

Our data demonstrate that independent of its role in lipoprotein uptake, absence of LRP in macrophages resulted in more advanced atherosclerosis and in lesions that contained more collagen and less CD3+ T cells. In contrast to previous in vitro studies, we conclude that macrophage LRP has an atheroprotective potential and may modulate the extracellular matrix in the atherosclerotic lesions.
Expression of LPL in Endothelial-Intact Artery Results in Lipid Deposition and Vascular Cell Adhesion Molecule-1 Upregulation in Both LPL and ApoE-Deficient Mice
Authors: Wang Jinyu , Xian Xunde , Huang Wei , Chen Li , Wu Liling , Zhu Yi , Fan Jianglin , Ross Colin , Hayden Michael R. , Liu George
Published: October 2006

Objective—

Overexpression of lipoprotein lipase (LPL) in deendothelialized artery led to profound localized lipid deposition. In this study the role of LPL in atherogenesis in endothelial-intact carotid arteries was assessed in genetically hyperlipidemic LPL- and ApoE-deficient mice.

Methods and Results—

Human wild-type LPL (hLPLwt), catalytically inactive LPL (hLPL194), or control alkaline phosphatase (hAP) were expressed in endothelial-intact carotid arteries via adenoviral vectors. Compared with Ad-hAP, lipid deposition in the arterial wall increased 10.0- and 5.1-fold for Ad-hLPLwt and Ad-hLPL194 in LPL-deficient mice, and 10.6- and 6.2-fold in ApoE-deficient mice, respectively. Vascular cell adhesion molecule-1 (VCAM-1) was upregulated in Ad-hLPLwt and Ad-hLPL194 transferred arteries.

Conclusions—

Endothelial cell associated LPL, either active or inactive, in the arterial wall is a strong proatherosclerotic factor in both LPL- and ApoE-deficient mice.
Tropical Cyclone Formations in the South China Sea Associated with the Mei-Yu Front
Authors: Lee Cheng-Shang , Lin Yung-Lan , Cheung Kevin K. W.
Published: October 2006

This study examines the 119 tropical cyclone (TC) formations in the South China Sea (SCS) during 1972–2002, and in particular the 20 in May and June. Eleven of these storms are associated with the weak baroclinic environment of a mei-yu front, while the remaining nine are nonfrontal. Seven of the 11 initial disturbances originated over land and have a highly similar evolution. Comparison of the frontal and nonfrontal formation shows that a nonfrontal formation usually occurs at a lower latitude, is more barotropic, develops faster, and possibly intensifies into a stronger TC. Six nonformation cases in the SCS are also identified that have similar low-level disturbances near the western end of a mei-yu front but did not develop further. In the nonformation cases, both the northeasterlies north of the front and the monsoonal southwesterlies are intermittent and weaker in magnitude so that the vorticity in the northern SCS does not spin up to tropical depression intensity. Because of the influence of a strong subtropical high, convection is suppressed in the SCS. The nonformation cases also have an average of 2–3 m s−1 larger vertical wind shear than the formation cases. A conceptual model is proposed for the typical frontal-type TC formations in the SCS that consists of three essential steps. First, an incipient low-level disturbance that originates over land moves eastward along the stationary mei-yu front. Second, the low-level circulation center with a relative vorticity maximum moves to the open ocean with the stationary front. Last, with strengthened northeasterlies, cyclonic shear vorticity continues to increase in the SCS, and after detaching from the stationary front, the system becomes a tropical depression.
Barotropic Instability at Minimal Resolution
Authors: Egger Joseph
Published: October 2006

Two linear minimum-resolution models of β-plane channel flow are presented in analogy to the well-known two-layer model of baroclinic instability in order to see if basic features of barotropic instability can be demonstrated using similarly simple models. Two models are discussed within this pedagogical framework. A spectral model with two wave modes is applied to a cosine jet. Necessary conditions for instability are derived. The stability analysis shows that this simple model captures the shortwave cutoff and the asymmetry of the instability with respect to the direction of the jet quite well. It is demonstrated that the cutoff follows from Fjörtoft’s theorem for wave triads. A gridpoint model with two points in the interior of the channel is discussed as well. An analog to the classical necessary condition for instability is derived. A stability problem in a nonrotating system is discussed where the mean flow velocity is constant near the walls and a linear shear flow is assumed near the channel’s axis. In this case, the stability characteristics of the low-order model come close to those of the full problem where a simple analytic solution is available. Addition of the β term stabilizes the flow. A proper choice of the initial conditions always enables short-term growth of the perturbation energy for stable mean flows. A qualitative interpretation of the instability mechanism is presented for both models, which exploits the fact that the locations of corresponding extrema of streamfunction and vorticity need not coincide. It is concluded that low-resolution models are well suited for a discussion of the basic features of barotropic instability.
A Multimodel Assessment of RKW Theory’s Relevance to Squall-Line Characteristics
Authors: Bryan George H. , Knievel Jason C. , Parker Matthew D.
Published: October 2006

The authors evaluate whether the structure and intensity of simulated squall lines can be explained by “RKW theory,” which most specifically addresses how density currents evolve in sheared environments. In contrast to earlier studies, this study compares output from four numerical models, rather than from just one. All of the authors’ simulations support the qualitative application of RKW theory, whereby squall-line structure is primarily governed by two effects: the intensity of the squall line’s surface-based cold pool, and the low- to midlevel environmental vertical wind shear. The simulations using newly developed models generally support the theory’s quantitative application, whereby an optimal state for system structure also optimizes system intensity. However, there are significant systematic differences between the newer numerical models and the older model that was originally used to develop RKW theory. Two systematic differences are analyzed in detail, and causes for these differences are proposed.
Structure, Growth Rates, and Tangent Linear Accuracy of Adjoint Sensitivities with Respect to Horizontal and Vertical Resolution
Authors: Ancell Brian C. , Mass Clifford F.
Published: October 2006

In this paper, the variation of adjoint sensitivities as horizontal and vertical resolutions are changed is investigated. The fifth-generation Pennsylvania State University–National Center for Atmospheric Research (PSU–NCAR) Mesoscale Model (MM5) and its adjoint are used with consistent physics to generate adjoint sensitivities over a 24-h period. The sensitivities are generated with respect to a response function defined as the lowest sigma level perturbation pressure over a region of northwestern Oregon. It is found that the scale, magnitude, and structure of sensitivity with respect to initial temperature varies significantly as grid spacing is decreased from 216 to 24 km. As found in other adjoint studies at relatively coarse resolution, low-level, upshear-tilted, subsynoptic-scale sensitivities were apparent, with the wavelike sensitivity pattern decreasing significantly in scale and spatial extent with increased horizontal resolution. It is also found that perturbation growth rates depend on horizontal resolution, with the adjoint sensitivities predicting larger changes in the response function with increased horizontal resolution. Relatively little change in sensitivity structure and growth rates occurred when the vertical resolution was varied from 10 to 50 vertical levels. It is shown that a majority of the predicted change in the response function comes from the very small proportion of the domain occupied by sensitive regions. Last, the accuracy of the tangent linear approximation is examined, and it is found that for perturbations made in sensitive regions, the tangent linear approximation degrades at finer grid spacing. The implications of these results are discussed for methodologies utilizing adjoint sensitivities, such as four-dimensional variational data assimilation and targeted observations strategies.
Cluster Analysis for Verification of Precipitation Fields
Authors: Marzban Caren , Sandgathe Scott
Published: October 2006

A statistical method referred to as cluster analysis is employed to identify features in forecast and observation fields. These features qualify as natural candidates for events or objects in terms of which verification can be performed. The methodology is introduced and illustrated on synthetic and real quantitative precipitation data. First, it is shown that the method correctly identifies clusters that are in agreement with what most experts might interpret as features or objects in the field. Then, it is shown that the verification of the forecasts can be performed within an event-based framework, with the events identified as the clusters. The number of clusters in a field is interpreted as a measure of scale, and the final “product” of the methodology is an “error surface” representing the error in the forecasts as a function of the number of clusters in the forecast and observation fields. This allows for the examination of forecast error as a function of scale.
A Climatology of Synoptic Conditions Associated with Significant Tornadoes across the Southern Appalachian Region
Authors: Gaffin David M. , Parker Stephen S.
Published: October 2006

A 54-yr climatology (1950–2003) of synoptic conditions associated with significant (F2 or greater) tornado events in the southern Appalachian region was compiled to 1) investigate the observed relative minimum of tornadoes in the Great Tennessee Valley, 2) test a hypothesis concerning northwest versus southwest 500-hPa flow events across the Great Tennessee Valley and Cumberland Plateau, 3) examine common operational forecasting techniques often used with synoptic-scale data to determine potentially tornadic environments, and 4) compare the patterns associated with significant, outbreak, and weak tornado events. Individual surface and upper-air charts along with composite charts closest to the time of significant tornado occurrences were used in this investigation. It was found that significant tornado events that occurred with prefrontal troughs (the most common surface boundary in the study) produced significant tornadoes almost exclusively over the Cumberland Plateau and southern Appalachian Mountains, with very few prefrontal trough events producing significant tornadoes in the Great Tennessee Valley of eastern Tennessee. Only four northwest 500-hPa flow events (which produced significant tornadoes almost exclusively in the southern Appalachian Mountains and during the summer) were found in this study, which refuted the initial hypothesis that northwest 500-hPa flow may produce tornadoes mainly in the Great Tennessee Valley with southwest 500-hPa flow producing tornadoes mainly across the Cumberland Plateau. Most significant tornado events in this study were associated with southwest 500-hPa flow ahead of a neutral-tilted trough, which revealed that the particular tilt of a 500-hPa trough does not necessarily enhance the formation of significant tornadoes in the southern Appalachian region. However, outbreak events (with five or more significant tornadoes) in the southern Appalachian region were typically associated with positive-tilted troughs. At 300 or 250 hPa, the southern Appalachian region was frequently located on the right side of a jet streak, with an even split between the entrance and exit regions. This finding indicated that significant tornado events in the southern Appalachian region did not necessarily favor the right-entrance or left-exit regions of a jet streak where rising motion is expected to be most intense (with straight jet streaks). A comparison of the composites of weak, significant, and outbreak tornado events revealed that wind dynamics were more important than instability in the distinction between weak and significant tornado events across the southern Appalachian region.
Cytotoxic CD4+ T cells use granulysin to kill Cryptococcus neoformans, and activation of this pathway is defective in HIV patients
Authors: Zheng Chun Fu , Ma Ling Ling , Jones Gareth J. , Gill M. John , Krensky Alan M. , Kubes Paul , Mody Christopher H.
Published: October 2006

An important mechanism of host defense to Cryptococcus neoformans involves the direct microbicidal activity of lymphocytes. The importance of CD4+ T cells is illustrated by the incidence of this infection in the acquired immunodeficiency syndrome (AIDS) patients; however, the relative activity of microbicidal CD4+ T cells compared with CD8+ T cells and natural killer (NK) cells has not been established. Further, although NK cells and CD8+ T cells use perforin or granulysin, respectively, to kill C neoformans, the effector molecule used by CD4+ T cells is not known. Experiments demonstrated that IL-2–activated peripheral blood lymphocytes from healthy adults acquire anticryptococcal activity, and surprisingly, that CD4+ T cells had the most profound effect on this activity. Using SrCl2induced degranulation and siRNA knockdown, granulysin was shown to be the effector molecule. Although activation by anti–CD3 + IL-2 resulted in the additional expression of perforin, this did not improve the anticryptococcal activity. Cryptococcal killing by CD4+ T cells was defective in human immunodeficiency virus (HIV)–infected patients due to dysregulated granulysin and perforin production in response to IL-2 or anti–CD3 + IL-2. In conclusion, CD4+ T cells are the major subset of cells responsible for killing C neoformans in peripheral blood. These cells use granulysin as the effector molecule, and priming is dysregulated in HIV-infected patients, which results in defective microbicidal activity.