bluuebunny/crossref_metadata_2025 huggingface dataset:
Sedimentology and geochemistry of an urban coastal lake system: Coombabah Lake Nature Reserve, Gold Coast, Queensland
Authors: FRANK T. D. , FIELDING C. R.
Published: May 2004

A study was initiated to address environmental concerns associated with changes in land use in the catchment area of Coombabah Lake, a brackish coastal lake system located in southeast Queensland. Sedimentological and geochemical data derived from a series of cores that penetrate the ca. 0–6000 year‐old lacustrine sequence indicate that throughout much of its history, Coombabah Lake has remained a quiet, shallow, water body fed by fine‐grained sediment dropped from suspension. Discrete and laterally continuous, shelly horizons form the basis for the stratigraphy developed for the lake sequence. A lithological transition in the upper 50 cm of the sediment column, from mud to shell‐rich, sandy mud, suggests that the depositional regime changed ∼500 years ago as accommodation space was filled. At this time, the dominant sedimentary processes changed to include reworking, partial bypass of sediment, the intermittent concentration of shell debris by winnowing, and the development of a flood‐tidal delta complex in the lower reaches of the lake. Sharp increases in total organic carbon, total nitrogen, and total phosphorus concentrations below the lithological transition at 50 cm depth suggest that the capacity of the system to preserve organic matter and trap nutrients decreased significantly after the transition in depositional regime. Results indicate that current conditions in Lake Coombabah are governed by natural processes associated with the long‐term evolution of coastal lake systems, and reveal little to suggest that there were any adverse affects resulting from recent human activities in the surrounding catchment.
Alunite alteration of tuffaceous layers and zircon dating, Upper Permian Kennedy Group, Carnarvon Basin, Western Australia
Authors: LEVER H. , FANNING C. M.
Published: May 2004

Alunite layers were found in two locations in the Binthalya Formation, Upper Kennedy Group, of Late Permian age, in the Merlinleigh Sub‐basin, onshore Carnarvon Basin. Alunite has not previously been reported from the Kennedy Group, or from a similar setting in Western Australia. The alunite occurs in discrete layers that have different chemical signatures to surrounding, unaltered sedimentary rocks. The lack of alteration in surrounding sedimentary rocks suggests that alteration was localised by initial differences in lithology, rather than by fortuitous localisation of alteration in a single layer. Alunite is thought to be the product of alteration of K‐feldspars, clay minerals and pyrite under acidic, specifically sulfuric, conditions. It is found in hydrothermal systems and weathering profiles. Because the precursor minerals of alunite are believed to be feldspars, clays and sulfur‐rich minerals, tuffaceous layers are the probable precursors of the alunite layers. Sulfur for the reaction was derived from within the tuffaceous deposits or from the oxidation of pyrite, which was probably present as cementation of trace fossils in other beds. The alteration is thought to have occurred during extensive oxidation, weathering and laterite formation during the Cenozoic, because the low density and powdery nature of the alunite indicates that it developed at a shallow depth. U–Pb dates obtained from zircons extracted from the alunite layers returned ages ranging from ca 2690 Ma to ca 270 Ma. The majority of zircons are inherited from the same source as the Kennedy Group sediments, indicating mixing of the initial tuffaceous layers with background sedimentation, either during the sedimentation process or afterwards by reworking or biological disturbance.
Development of Type 2 fold interference patterns in the Broken Hill Block: implications for strain partitioning across a detachment during the Olarian Orogeny
Authors: FORBES C. J. , BETTS P. G.
Published: May 2004

A north–south‐trending relatively high‐strain shear zone active during the earliest stages of the ca 1.60–1.58 Ga Olarian Orogeny bounds domains characterised by different structural geometries in the northern Broken Hill Block. To the west of the shear zone Freyers Metasediments preserve Type 2 'mushroom' fold interference patterns between fold generations F2 and F3. Recumbent F2 folds are highly non‐cylindrical. These were subsequently overprinted by north‐orientated close to tight upright folds (F3). To the east of the shear zone, in the Parnell Formation, F2 folds are not developed and the structural grain reflects the F3 folding event. The shear zone is interpreted to represent a local detachment that accommodated lateral transportation of hangingwall rocks, producing non‐cylindrical recumbent folding during thin‐skinned deformation (D2). F3 folds represent thick‐skinned deformation during the late stages of the Olarian Orogeny, folding rocks above and below the detachment. This resulted in zones of different structural geometry and strain pattern across the detachment.
Evidence of Late Cenozoic uplift and climate change in the stratigraphy of the Macquarie River valley, New South Wales
Authors: TOMKINS K. M. , HESSE P. P.
Published: May 2004

The stratigraphy of the alluvial sediments filling the Macquarie River valley, New South Wales, was investigated to test models of landscape evolution of the rifted margin Eastern Highlands of Australia. In the neighbouring Lachlan River valley, the stratigraphy of Neogene sediments has been incorporated into a model proposing denudation and episodic passive (denudational isostatic) uplift of the highlands throughout the Neogene. In this study, we aimed to test the regional extent of this model and the influence of sediment supply on the stratigraphic record and its interpretation. The sediments of the Macquarie River valley show three major changes in the depositional regime. First, erosion of the valley basement in the Late Miocene was followed by (and possibly synchronous with) deposition of a basal clay and sand unit in the Late Miocene. Second, the valley was filled with a wedge of sediment containing abundant gravel and sand in the Pliocene; and third, the older gravelly unit was eroded and reworked in the Quaternary, and a sandy clay unit, which forms the modern floodplain, was deposited. Deformation of the Middle Miocene basalt‐filled valley provides good evidence for substantial uplift of the highlands in the Middle–Late Miocene, synchronous with or shortly after widespread volcanism, but continuing no later than the Late Miocene. The Pleistocene incision is best accounted for by climate change to drier conditions, triggering a sediment‐starved response by the Macquarie River, rather than further uplift. While valley incision and subsequent infilling can be viewed as a response to tectonism, the internal sedimentology and stratigraphy of the sediments appears to respond to fluctuations in sediment supply brought about by extrinsic climate change and intrinsic catchment lithology. The first‐order tectonic events are not synchronous with uplift in the Lachlan valley and are restricted to relatively local spatial scales. However, the secondary climatic forcing has a broader regional expression.
STATE‐DEPENDENT PREFERENCES AND FUTURES HEDGING: THE EFFECTS OF BASIS RISK
Authors: Lien Donald
Published: May 2004

Abstract.  This note incorporates basis risk into the futures hedging decision‐making problem when the hedger has a state‐dependent preference. It is shown that, in an unbiased futures market, a partial hedge is optimal when the marginal utilities in different states are moderately close to each other. Conditions for a Texas hedge or an overhedge are provided. Finally, it is demonstrated that basis risk always reduces the futures trading volume.
Is the Lending Channel of Monetary Policy Dominant in Australia?
Authors: Suzuki Tomoya
Published: May 2004

The transmission process of monetary policy is a longstanding macroeconomic issue. The lending view is that a monetary tightening affects aggregate demand by shifting the supply schedule of bank loans left. The contraction of bank loans does not necessarily mean a shift of the supply schedule. Therefore, testing the lending view requires the identification of the shifts of the demand and supply schedules in the bank loan market. This paper employs an original approach, finding that the lending channel is not dominant in Australia. The paper also examines features of Australian banks’ behaviour which make the lending channel less dominant.
Sources of Australia's Productivity Revival
Authors: Parham Dean
Published: May 2004

Australia's annual rate of multifactor productivity growth accelerated a full percentage point in the 1990s. The fact that most other OECD countries did not share this experience suggests that domestic factors must have provided at least a major part of the explanation. This article establishes six stylised facts about Australia's 1990s productivity performance and then surveys available analytical studies to find explanations for them. With few aggregate models available to shed light on recent output and productivity growth, the survey also covers cross‐country, industry and firm‐level studies. Despite various shortcomings in data and specification of models, a reasonably clear picture emerges. The accumulation of physical and human capital has laid a long‐term foundation for productivity growth. On top of this foundation, the greater openness of the economy to trade and investment, increased R&D activity and a strong uptake and innovative use of ICT have been specific sources of the productivity revival. There is also evidence that policy and institutional factors have been important in driving and enabling these determinants.
The structural context of recent transitions to democracy
Authors: DOORENSPLEET RENSKE
Published: May 2004

Abstract.  In general, the literature on democratic transitions has focused on political processes and choices of actors in explaining regime change, thereby failing to investigate whether structural factors affect the recent rise in transitions to democracy. An analysis of the influence of these structural factors is however important, and it has not yet been done in a systematic way in order to explain recent transitions to democracy since 1989. It will be shown that some structural factors indeed play a role in generating transitions to democracy. These results contradict the idea that structural factors can be ignored when explaining recent transitions to democracy. An additional finding in this article is that some structural factors, such as economic development, growth and a country's role in the world‐system had an unexpected impact on democratic transitions since the end of the Cold War. These findings set bounds to the strength of the modernization and world‐system theories to explain transitions to democracy, but on the other hand, democratic diffusion played a significant role after 1989. In the (structural) context in which a state had a peripheral role, a low level of economic growth and a high proportion of democratic neighbors, the probability of a state's transition to democracy was high. This structural context seemed to be fertile soil for recent transitions to democracy.
Concentric Remodeling Detection by Magnetocardiography in Patients with Recent Onset Arterial Hypertension
Authors: COMANI SILVIA , GALLINA SABINA , LAGATTA ANTONIO , ORLANDI MARCO , MORANA GIOVANNI , LUZIO SILVANO DI , BRISINDA DONATELLA , DE CATERINA RAFFAELE , FENICI RICCARDO , ROMANI GIAN LUCA
Published: May 2004

The aim of this work was to evaluate a number of magnetocardiographic (MCG) indices in their predictive ability for left ventricular (LV) concentric remodeling. Twenty‐five male patients affected by essential hypertension for no longer than 15 months and presenting signs of LV remodeling participated in the study; 25 normal men volunteers of comparable age were evaluated as controls. All participants underwent echocardiography (ECHO), electrocardiography (ECG), and magnetocardiography (MCG). Several MCG based indices were evaluated, namely the QRS Integral, T Integral, QRS‐T Integral, T/QRS Integral, RS Index, and the variations of the electrical cardiac axis (ECA) orientation. MCG indices were compared with ECHO parameters, i.e., left ventricular mass index (LVMI) and relative wall thickness (RWT), and with ECG parameters, i.e., 12‐lead standard ECG LVH Sokolow‐Lyon and Cornell voltages. QRS Integral values for patients and controls were significantly different (P = 0.03), whereas T Integral values showed only a tendency to differentiate between patients and controls (P = 0.15). No significant correlation between MCG and echocardiographic indices in patients was found; RWT showed a tendency to correlate with QRS Integral (r = 0.34, P = 0.17) and with RS Index (r = 0.49, P = 0.15), and LVMI showed a tendency to correlate with the variations of the ECA orientation (r = 0.38, P = 0.10). Our findings, also supported by preliminary results on patients affected by hypertension induced LV hypertrophy, suggest a potential role of MCG in the evaluation of early electrophysiological alterations due to LV concentric remodeling. (PACE 2004; 27[Pt. I]:709–718)
Intramural Radiofrequency Ablation:
Authors: KOVOOR PRAMESH , DALY MICHAEL , CAMPBELL CRAIG , DEWSNAP BARBARA , EIPPER VICKI , UTHER JOHN , ROSS DAVID
Published: May 2004

The aim of this study was to evaluate intramural temperature‐controlled radiofrequency ablation by determining the intramural temperature profile during ablation and by correlating lesion geometry with intramural electrode size and temperature. Intramural ablation might be useful to create deeper lesions for ventricular tachycardia secondary to underlying heart disease. Intramural radiofrequency ablation was performed in 17 greyhounds at thoracotomy, from an epicardial approach, using a 21‐gauge needle electrode. Sixty‐eight lesions were created in 11 dogs at electrode temperatures of 70°C, 80°C, 90°C, and 100°C for 60 seconds. Intramural thermocouples at 1‐, 2‐, 3‐, 4‐, and 5‐mm distances were used to identify simultaneous intramural temperature profile. An epicardial approach was used to ensure accurate positioning of the ablating and temperature monitoring needles within the myocardium with fixed interneedle distances. Ninety‐nine radiofrequency ablations were performed in six greyhounds using three different intramural electrode lengths (1 mm, 2.5 mm, and 5.5 mm). Lesions were created at 70°C, 80°C, and 90°C for 60 seconds. All lesions were measured after staining with Gomori Trichrome. Lesion dimensions increased in a highly predictable manner with increasing electrode temperature or length. There was no popping or charring, even with target electrode temperature of 100°C. There was significant correlation between intramural temperature 4 mm from the ablating electrode and lesion width (P < 0.001, R2= 0.45) and depth (P = 0.02, R2= 0.08). Feedback control of electrode temperature enables reliable intramural radiofrequency ablation without impedance rise even with target electrode temperature of 100°C. Increasing the length of the intramural ablating electrode to ≥ 5.5 mm and increasing temperatures to 90°C–100°C creates the largest lesions. (PACE 2004; 27[Pt. I]:719–725)
Ventricular Activation Onset‐Triggered Left Ventricular Pacing:
Authors: WONG GEORGE K. , FLORENDO FEDERICO T. , COHEN FRED M.
Published: May 2004

Ventricular activation onset‐triggered (VAOT) left ventricular pacing modalities synchronize left ventricular paced activation with existing intrinsic ventricular activation, in patients with complete LBBB and adequate rate. The purpose of this study was to evaluate the safety and feasibility of VAOT pacing with one left ventricular pacing lead, during temporary pacing in the postoperative period following open heart surgery. VAOT pacing was studied in five patients with LBBB and two patients with previously implanted right ventricular pacemakers. The VAOT pacing system used was assembled by modifying the function of existing equipment and its programming is described in detail. Comparative ECGs are reported, documenting the changes in ventricular activation produced by VAOT pacing. Stability of surface ECG acquisition was found to be essential to the success of temporary VAOT pacing and inappropriate pacing due to ECG instability is described. Patients were studied at rest and none experienced congestive heart failure. In the comparison of cardiac output, with and without VAOT pacing, no significant differences were found in LBBB patients or those with right ventricular pacemakers. In the comparison of arterial pressure, with and without VAOT pacing, no significant differences were found in six patients, however, in one LBBB patient with intrinsic predominant ventricular trigeminy, VAOT pacing was observed to have an antiarrhythmic effect resulting in suppression of ventricular ectopy and stabilization of arterial pressure. All patients survived VAOT pacing and the postoperative period without complications requiring additional intervention or treatment. (PACE 2004; 27[Pt. I]:730–739)
Efficacy of Biphasic Shock for Transthoracic Cardioversion of Persistent Atrial Fibrillation:
Authors: WOŻAKOWSKA‐KAPLON BEATA , JANION MARIANNA , SIELSKI JANUSZ , RADOMSKA EDYTA , BA̧KOWSKI DAWID , BARTKOWIAK RADOSLAW
Published: May 2004

Although electrical cardioversion of atrial fibrillation (AF) is frequently performed, initial energy requirements for cardioversion of persistent AF is still a matter of debate. The aim of the study was to determine the efficacy of biphasic shocks for transthoracic cardioversion of persistent AF and to predict adequate initial energy. A prospective study enrolled 94 consecutive patients with persistent AF, who were referred for elective cardioversion with a biphasic waveform. The paddles were placed in the anterolateral position. A step‐up protocol was used to estimate the cardioversion threshold. The initial shock energy was 50 J, with subsequent increments to 100, 200, and 300 J in the event of cardioversion failure. The mean age of the study group was of about 65 years (6 ± 11 years) and a median duration of AF was 65 days (3–324). Sixty‐two out of 94 patients were men, 55% of the study population was classified as having well‐controlled hypertension. The overall success rate of cardioversion was 89%, with a mean 2.2 ± 1.4 shocks, and effective J 217.8 ± 113 delivered during repeated cardioversions. The success rate of low energy shocks: 50 and 50 +100 J was 51%. By logistic regression analysis the only independent predictor of success at low energy shock was shorter duration of AF (r =−0.51; P = 0.02). Patients with shorter duration of AF have a higher probability for successful cardioversion with low energy. In patients with longer AF duration, a 200 J shock should be considered for cardioversion as the initial energy. (PACE 2004; 27[Pt. I]:764–768)
Pacemaker Mediated Tachycardia as a Complication of the Autointrinsic Conduction Search Function
Authors: DENNIS MALCOLM J. , SPARKS PAUL B.
Published: May 2004

The autointrinsic conduction search (AICS) option, featured on some DDD pacemakers, performs periodic assessments of atrioventricular (AV) conduction capability during a single beat AV delay extension. Demonstration of ventricular conduction during the prolonged AV delay, permits ongoing AV delay extension if the patient's intrinsic conduction is preferred to ventricular pacing. A case is presented where the wide separation of atrial and ventricular pacing during the conduction search permitted retrograde ventriculoatrial conduction, precipitating pacemaker mediated tachycardia (PMT) on seven occasions in one patient. Two onset patterns are reported, both attributable to the AICS option. Recommendations for prevention strategies are made. (PACE 2004; 27[Pt. I]:824–826)
Is Right Ventricular Outflow Tract Pacing an Alternative to Left Ventricular/Biventricular Pacing?
Authors: RIEDLBAUCHOVÁ LUCIE , KAUTZNER JOSEF , HATALA ROBERT , BUCKINGHAM THOMAS A.
Published: May 2004

The right ventricular apex has been used as the traditional pacing site since the development of transvenous pacing in 1959. Some studies suggest that pacing the right ventricular apex may cause remodeling and is harmful. In the past decade, there have been a multitude of studies of the hemodynamic, electrophysiological, electrocardiographic, and clinical effects of ventricular pacing at other sites. Pacing of the left ventricle singly or with biventricular pacing has emerged as an effective and safe therapy for moderate to severe congestive heart failure in patients with prolonged QRS complexes. Studies of alternate right ventricular sites, like the right ventricular outflow tract, have given mixed results. Not all patients can be treated with left ventricular pacing, which is a time‐consuming and difficult procedure. Right ventricular pacing is easier and less expensive than left ventricular pacing and further study of additional right ventricular sites seems warranted. (PACE 2004; 27[Pt. II]:871–877)
Magnetic resonance imaging of the palmar aspect of the equine podotrochlear apparatus: normal appearance
Authors: Busoni Valeria , Snaps Frédéric , Trenteseaux Jacques , Dondelinger Robert F.
Published: May 2004

The purpose of this study was to describe the normal magnetic resonance (MR) imaging characteristics of the palmar structures of the equine podotrochlear apparatus by means of retrospective evaluation of MR imaging studies of 16 cadaver limbs. The articular aspect of the distal sesamoid bone was not evaluated in this study. Equine digits were imaged with a human knee radiofrequency coil in a 1.5 T magnetic field, using spin echo (SE) T1‐weighted, turbo spin echo proton density (TSE PD)‐weighted with and without fat saturation (FS), and FS TSE T2‐weighted sequences. The limbs were dissected after imaging to validate the absence of gross abnormalities of the flexor aspect of the distal sesamoid bone, of the deep digital flexor tendon, and the distal impar sesamoidean ligament. Seven deep digital flexor tendons were subjected to histologic examination to exclude any microscopic tendon pathology. The anatomic structures of the podotrochlear apparatus were easily identified on MR images. Compact bone of the flexor cortex of the distal sesamoid bone had low intensity signal on all sequences. In 11 digits an increased signal was seen within the thickness of the sagittal eminence of the flexor cortex in SE T1‐weighted images and in TSE PD‐weighted images without FS. Trabecular bone had a granular appearance and high signal in SE T1‐weighted sequences and TSE images without FS. The deep digital flexor tendon had low signal on FS T2‐weighted images, while on short echo time sequences (T1‐ and PD‐weighted sequences), the tendon signal varied depending on the relative orientation between its fibers and the static magnetic field. Seven tendons had stippled appearance due to small intratendonous foci of slightly increased signal on transverse T1‐weighted images. MR imaging provides a thorough evaluation of the anatomical structure of the podotrochlear apparatus: A good knowledge of the MR imaging appearance and anatomy and an awareness of potential pitfalls will improve diagnostic specificity for the detection of pathologic changes.
Accuracy of increased large‐intestine wall thickness during ultrasonography for diagnosing large‐colon torsion in 42 horses
Authors: Pease Anthony P. , Scrivani Peter V. , Erb Hollis N. , Cook Vanessa L.
Published: May 2004

Large‐colon torsion is a common cause of colic in horses and has a worse prognosis and higher cost than other causes of surgical colic of the large colon. During large‐colon torsion, the colon wall becomes thick due to vascular occlusion. Therefore, we hypothesized that detecting increased colon wall thickness during ultrasonography would be an accurate preoperative test for large‐colon torsion. The sample population consisted of 42 horses that were admitted for surgical treatment of colic localized to the large colon. The diagnosis was confirmed at surgery or necropsy examination. Twelve (29%) of these horses were diagnosed with large‐colon torsion. Duplicate ultrasonographic measurements of colon wall thickness were made at six abdominal locations and an average measurement was calculated. For four of these six sites, a significant difference (P<0.005) was detected between horses with and without large‐colon torsion. All four tests were moderately sensitive and highly specific for diagnosing large‐colon torsion using five decision criteria. Using a ventral abdominal window, a colon wall thickness ≥9 mm accurately predicted large‐colon torsion in eight of the 12 horses (sensitivity, 67%; confidence interval [CI], 36–98%) and correctly predicted that large‐colon torsion was absent in 28/28 horses (specificity 100%; CI, 98–100%). Intraobserver repeatability was assessed by evaluating the difference between the first and second measurements obtained, which was ≤2 mm. Therefore, detecting increased large‐colon wall thickness during ultrasonography is a reproducible and accurate preoperative test for large‐colon torsion in horses with surgical colic localized to the large colon.
Impaired regulation of neuronal nitric oxide synthase and heart rate during exercise in mice lacking one nNOS allele
Authors: Danson E. J. F. , Mankia K. S. , Golding S. , Dawson T. , Everatt L. , Cai S. , Channon K. M. , Paterson D. J.
Published: May 2004

We tested the hypothesis that a single allele deletion of neuronal nitric oxide synthase (nNOS) would impair the neural control of heart rate following physical training, and that this phenotype could be restored following targeted gene transfer of nNOS. Voluntary wheel‐running (+EX) in heterozygous nNOS knockout mice (nNOS+/−, +EX; n= 52; peak performance 9.1 ± 1.8 km day−1) was undertaken and compared to wild‐type mice (n= 38; 9.5 ± 0.8 km day−1). In anaesthetized wild‐type mice, exercise increased phenylephrine‐induced bradycardia by 67% (measured as heart rate change, in beats per minute, divided by the change in arterial blood pressure, in mmHg) or pulse interval response to phenylephrine by 52% (measured as interbeat interval change, in milliseconds, divided by the change in blood pressure). Heart rate changes or interbeat interval changes in response to right vagal nerve stimulation were also enhanced by exercise in wild‐type atria (P < 0.05), whereas both in vivo and in vitro responses to exercise were absent in nNOS+/− mice. nNOS inhibition attenuated heart rate responses to vagal nerve stimulation in all atria (P < 0.05) and normalized the responses in wild‐type, +EX with respect to wild‐type with no exercise (−EX) atria. Atrial nNOS mRNA and protein were increased in wild‐type, +EX compared to wild‐type, −EX (P < 0.05), although exercise failed to have any effect in nNOS+/− atria. In vivo nNOS gene transfer using adenoviruses targeted to atrial ganglia enhanced choline acetyltransferase–nNOS co‐localization (P < 0.05) and increased phenylephrine‐induced bradycardia in vivo and heart rate responses to vagal nerve stimulation in vitro compared to gene transfer of enhanced green fluorescent protein (eGFP, P < 0.01). This difference was abolished by nNOS inhibition (P < 0.05). In conclusion, genomic regulation of NO bioavailability from nNOS in cardiac autonomic ganglia in response to training is dependent on both alleles of the gene. Although basal expression of nNOS is normal, polymorphisms of nNOS may interfere with neural regulation of heart rate following training. Targeted gene transfer of nNOS can restore this impairment.
Facilitating roles of murine platelet glycoprotein Ib and αIIbβ3 in phosphatidylserine exposure during vWF–collagen‐induced thrombus formation
Authors: Kuijpers Marijke J. E. , Schulte Valerie , Oury Cécile , Lindhout Theo , Broers Jos , Hoylaerts Marc F. , Nieswandt Bernhard , Heemskerk Johan W. M.
Published: May 2004

Vessel wall damage exposes collagen fibres, to which platelets adhere directly via the collagen receptors glycoprotein (GP) VI and integrin α2β1 and indirectly by collagen‐bound von Willebrand factor (vWF) via the GPIb‐V‐IX and integrin αIIbβ3 receptor complexes. Platelet–collagen interaction under shear stimulates thrombus formation in two ways, by integrin‐dependent formation of platelet aggregates and by surface exposure of procoagulant phosphatidylserine (PS). GPVI is involved in both processes, complemented by α2β1. In mouse blood flowing over collagen, we investigated the additional role of platelet–vWF binding via GPIb and αIIbβ3. Inhibition of GPIb as well as blocking of vWF binding to collagen reduced stable platelet adhesion at high shear rate. This was accompanied by delayed platelet Ca2+ responses and reduced PS exposure, while microaggregates were still formed. Inhibition of integrin αIIbβ3 with JON/A antibody, which blocks αIIbβ3 binding to both vWF and fibrinogen, reduced PS exposure and aggregate formation. The JON/A effects were not enhanced by combined blocking of GPIb–vWF binding, suggesting a function for αIIbβ3 downstream of GPIb. Typically, with blood from FcR γ‐chain +/− mutant mice, expressing 50% of normal platelet GPVI levels, GPIb blockage almost completely abolished platelet adhesion and PS exposure. Together, these data indicate that, under physiological conditions of flow, both adhesive receptors GPIb and αIIbβ3 facilitate GPVI‐mediated PS exposure by stabilizing platelet binding to collagen. Hence, these glycoproteins have an assistant procoagulant role in collagen‐dependent thrombus formation, which is most prominent at reduced GPVI activity and is independent of the presence of thrombin.
Circulating ATP‐induced vasodilatation overrides sympathetic vasoconstrictor activity in human skeletal muscle
Authors: Rosenmeier Jaya B. , Hansen Jim , González‐Alonso José
Published: May 2004

Despite increases in muscle sympathetic vasoconstrictor activity, skeletal muscle blood flow and O2 delivery increase during exercise in humans in proportion to the local metabolic demand, a phenomenon coupled to local reductions in the oxygenation state of haemoglobin and concomitant increases in circulating ATP. We tested the hypothesis that circulating ATP contributes to local blood flow and O2 delivery regulation by both inducing vasodilatation and blunting the augmented sympathetic vasoconstrictor activity. In eight healthy subjects, we first measured leg blood flow (LBF) and mean arterial pressure (MAP) during three hyperaemic conditions: (1) intrafemoral artery adenosine infusion (vasodilator control), (2) intrafemoral artery ATP infusion (vasodilator), and (3) mild knee‐extensor exercise (∼20 W), and then compared the responses with the combined infusion of the vasoconstrictor drug tyramine, which evokes endogenous release of noradrenaline from sympathetic nerve endings. In all three hyperaemic conditions, LBF equally increased from ∼0.5 ± 0.1 l min−1 at rest to ∼3.6 ± 0.3 l min−1, with no change in MAP. Tyramine caused significant leg vasoconstriction during adenosine infusion (53 ± 5 and 56 ± 5% lower LBF and leg vascular conductance, respectively, P < 0.05), which was completely abolished by both ATP infusion and exercise. In six additional subjects resting in the sitting position, intrafemoral artery infusion of ATP increased LBF and leg vascular conductance 27 ± 3‐fold, despite concomitant increases in venous noradrenaline and muscle sympathetic nerve activity of 2.5 ± 0.2‐ and 2.4 ± 0.1‐fold, respectively. Maximal ATP‐induced vasodilatation at rest accounted for 78% of the peak LBF during maximal bicycling exercise. Our findings in humans demonstrate that circulating ATP is capable of regulating local skeletal muscle blood flow and O2 delivery by causing substantial vasodilatation and negating the effects of increased sympathetic vasoconstrictor activity.
QUANTITATIVE DOUBLE-TRACER DIGITALRADIOGRAPHY BASED ON DESMETHYLIMIPRAMINE DEPOSITION: APPLICATION TO STUDIES ON MYOCARDIAL PERFUSION HETEROGENEITY
Authors: TACHIBANA HIROYUKI , MATSUMOTO TAKESHI , OGASAWARA YASUO , KODAMA TAKAO , KAJIYA FUMIHIKO
Published: May 2004

Desmethylimipramine (DMI), an α2-adrenergic antagonist, is a nearly ideal deposition tracer for evaluating the myocardial flow distribution with the least artifactual effects on microcirculation. Myocardial retentions of tritium- and iodine-125-labeled DMI (HDMI, IDMI) were confirmed to be satisfactory; the retentions of IDMI and HDMI at 1 min were 95 and 91% respectively in isolated Tyrode-perfused rabbit hearts (n=6) at a perfusion rate of 8.1 ml/min/g, and 98 and 96% respectively, in blood-perfused rat hearts (n=4) at a perfusion rate of 3.1 ml/min/g. Using these tracers combined with subtraction digitalradiography, it allowed the assessing of changes of myocardial flow distribution with 400×400 μ m 2 resolution. In blood-perfused rat hearts (n=4), the validity of this method was verified by the strong cross-correlation between regional densities of two tracers injected simultaneously (r=0.94) and the regression line having a slope close to one. Furthermore, in Tyrode-perfused rabbit hearts, the flow distributions were evaluated before and after decreasing perfusion rate moderately by 34% (n=7) and severely by 70% (n=7). Severe flow reduction increased the coefficient of variation of tracer density (CV) significantly from 19 to 25%, but CV did not change with moderate flow reduction (20 vs. 19%). Regional densities of two tracers were cross-correlated still substantially under severe low-flow perfusion (r=0.84). Accordingly, flow differences between originally high- and low-flow regions were enlarged under severe flow reduction. In conclusion, double-tracer digitalradiography based on the DMI deposition will be a potent method for the analysis of flow heterogeneity at microvascular levels.
Protective role of extracellular chloride in fatigue of isolated mammalian skeletal muscle
Authors: Cairns Simeon P. , Ruzhynsky Vladimir , Renaud Jean-Marc
Published: May 2004

A possible role of extracellular Cl− concentration ([Cl−]o) in fatigue was investigated in isolated skeletal muscles of the mouse. When [Cl−]o was lowered from 128 to 10 mM, peak tetanic force was unchanged, fade was exacerbated (wire stimulation electrodes), and a hump appeared during tetanic relaxation in both nonfatigued slow-twitch soleus and fast-twitch extensor digitorum longus (EDL) muscles. Low [Cl−]o increased the rate of fatigue 1) with prolonged, continuous tetanic stimulation in soleus, 2) with repeated intermittent tetanic stimulation in soleus or EDL, and 3) to a greater extent with repeated tetanic stimulation when wire stimulation electrodes were used rather than plate stimulation electrodes in soleus. In nonfatigued soleus muscles, application of 9 mM K+ with low [Cl−]o caused more rapid and greater tetanic force depression, along with greater depolarization, than was evident at normal [Cl−]o. These effects of raised [K+]o and low [Cl−]o were synergistic. From these data, we suggest that normal [Cl−]o provides protection against fatigue involving high-intensity contractions in both fast- and slow-twitch mammalian muscle. This phenomenon possibly involves attenuation of the depolarization caused by stimulation- or exercise-induced run-down of the transsarcolemmal K+ gradient.
Preload-adjusted right ventricular maximal power: concept and validation
Authors: Schenk Soren , Popović Zoran B. , Ochiai Yoshie , Casas Fernando , McCarthy Patrick M. , Starling Randall C. , Kopcak Michael W. , Dessoffy Raymond , Navia Jose L. , Greenberg Neil L. , Thomas James D. , Fukamachi Kiyotaka
Published: May 2004

Right ventricular (RV) maximal power (PWRmx) is dependent on preload. The objective of this study was to test our hypothesis that the PWRmx versus end-diastolic volume (EDV) relationship, analogous to the load-independent stroke work (SW) versus EDV relationship (preload-recruitable SW, PRSW), is linear, with the PWR x-axis intercept (V0PWR) corresponding to the PRSW intercept (V0SW). If our hypothesis is correct, the preload sensitivity of PWRmx could be eliminated by adjusting for EDV and V0PWR. Ten dogs were instrumented with a pulmonary flow probe, micromanometers, and RV conductance catheter. Data were obtained during bicaval occlusions under various conditions and fitted to PWRmx = a·(EDV − V0PWR)β, where a is the slope of the relationship. The PWRmx versus EDV relationship did not deviate from linearity (β = 1.09, P = not significant vs. 1), and V0PWR correlated with V0SW ( r = 0.93, P <0.0001). V0PRW was related to steady-state EDV and left ventricular end-diastolic pressure, allowing for estimation of V0PWR (V0Est) and single-beat PWRmx preload adjustment. Dividing PWRmx by the difference of EDV and V0PWR (PAMPV0PWR) eliminated preload dependency down to 50% of the baseline EDV. PWRmx adjustment using V0Est (PAMPV0Est) showed similar preload independency. Enhancing contractility increased PAMPV0PWR and PAMPV0Est from 176 ± 52 to 394 ± 205 W/ml × 104 and 145 ± 51 to 404 ± 261 W/ml × 104, respectively, accompanied by an increase of PRSW from 13.0 ± 4.5 to 29.7 ± 16.4 mmHg (all P <0.01). PAMPV0PWR and PAMPV0Est correlated with PRSW ( r = 0.85; r = 0.77; both P <0.001). Numerical modeling confirmed the accuracy of our experimental data. Thus preload adjustment of PWRmx should consider a linear PWRmx versus EDV relationship with distinct V0PWR. PAMPV0PWR is a preload-independent estimate of RV contractility that may eventually be determined noninvasively.
Angiotensin II stimulates nitric oxide production in pulmonary artery endothelium via the type 2 receptor
Authors: Olson Susan , Oeckler Richard , Li Xinmei , Du Litong , Traganos Frank , Zhao Xiangmin , Burke-Wolin Theresa
Published: May 2004

We previously reported that angiotensin II stimulates an increase in nitric oxide production in pulmonary artery endothelial cells. The aims of this study were to determine which receptor subtype mediates the angiotensin II-dependent increase in nitric oxide production and to investigate the roles of the angiotensin type 1 and type 2 receptors in modulating angiotensin II-dependent vasoconstriction in pulmonary arteries. Pulmonary artery endothelial cells express both angiotensin II type 1 and type 2 receptors as assessed by RT-PCR, Western blot analysis, and flow cytometry. Treatment of the endothelial cells with PD-123319, a type 2 receptor antagonist, prevented the angiotensin II-dependent increase in nitric oxide synthase mRNA, protein levels, and nitric oxide production. In contrast, the type 1 receptor antagonist losartan enhanced nitric oxide synthase mRNA levels, protein expression, and nitric oxide production. Pretreatment of the endothelial cells with either PD-123319 or an anti-angiotensin II antibody prevented this losartan enhancement of nitric oxide production. Angiotensin II-dependent enhanced hypoxic contractions in pulmonary arteries were blocked by the type 1 receptor antagonist candesartan; however, PD-123319 enhanced hypoxic contractions in angiotensin II-treated endothelium-intact vessels. These data demonstrate that angiotensin II stimulates an increase in nitric oxide synthase mRNA, protein expression, and nitric oxide production via the type 2 receptor, whereas signaling via the type 1 receptor negatively regulates nitric oxide production in the pulmonary endothelium. This endothelial, type 2 receptor-dependent increase in nitric oxide may serve to counterbalance the angiotensin II-dependent vasoconstriction in smooth muscle cells, ultimately regulating pulmonary vascular tone.
CpG DNA-mediated immune response in pulmonary endothelial cells
Authors: Li Jiang , Ma Zheng , Tang Zhi-Lue , Stevens Troy , Pitt Bruce , Li Song
Published: May 2004

Although the CpG DNA immune response mediated by Toll-like receptor 9 (TLR9) has been extensively studied in a number of immune cells, the response to CpG DNA in endothelial cells (EC) is not well understood. In this study, we show that both mouse and rat lung EC display constitutive expression of TLR9 mRNA. Exposure to CpG DNA induced a potent proinflammatory response as manifested by an increased expression of IL-8 and ICAM-1 in mouse pulmonary EC. The proinflammatary response was sensitive to chloroquine, consistent with a role of endosomal contribution. A role for p38 MAPK and NF-κB pathway was apparent as the response was sensitive to inhibitors of p38 MAPK and NF-κB but was not affected by inhibitors of ERK1/2. A synergistic effect of CpG DNA and LPS on the inflammatory response is consistent with multiple TLR interaction in EC. This study suggests a possible role for CpG DNA-mediated EC immune response in the host defense system. It also has important implications in plasmid DNA-mediated pulmonary endothelium gene transfer.
Molecular identification and characterization of three isoforms of tachykinin NK1-like receptors in the cane toadBufo marinus
Authors: Liu Lu , Markus Irit , Vandenberg Robert J. , Neilan Brett A. , Murray Michael , Burcher Elizabeth
Published: May 2004

The tachykinin peptide bufokinin, isolated from the cane toad intestine, is important in intestinal and cardiovascular regulation in the toad. In this study, three tachykinin NK1-like receptor isoforms, bNK1-A, bNK1-B, and bNK1-C, encoding proteins of 309, 390, and 371 amino acids, respectively, were cloned from the toad brain and intestine. These isoforms differ only at the intracellular COOH terminus. The bNK1-A and bNK1-B isoforms are similar to the truncated and full-length forms of the mammalian NK1receptor, whereas bNK1-C is unique and does not correspond to any previously described receptor. RT-PCR studies demonstrated that three isoform transcripts are widely distributed in the toad with high expression in gut, spinal cord, brain, lung, and skeletal muscle. When expressed in COS-7 cells, bufokinin showed similar high affinity (IC500.6–0.8 nM) in competing for125I-labeled Bolton-Hunter bufokinin binding at all receptors, but the binding affinities of substance P (SP) and neurokinin A (NKA) were very different at each isoform. When expressed in Xenopus oocytes, the truncated isoform, bNK1-A, was inactive, whereas bNK1-B and bNK1-C produced changes in chloride current when stimulated by tachykinins (minimum concentrations: bufokinin, 0.1 nM; SP, 1 nM; and NKA, 10 nM). A marked desensitization of the response was seen to subsequent applications of tachykinins, as experienced by the mammalian NK1receptor. In summary, our study describing three isoforms of NK1-like receptor from the toad suggests that the alternative splicing of NK1receptor is a physiologically conserved mechanism and raises a fundamental question as to the physiological role of each isoform.
A long-term high-protein diet markedly reduces adipose tissue without major side effects in Wistar male rats
Authors: Lacroix Magali , Gaudichon Claire , Martin Antoine , Morens Céline , Mathé Véronique , Tomé Daniel , Huneau Jean-François
Published: May 2004

Although there is a considerable interest of high-protein, low-carbohydrate diets to manage weight control, their safety is still the subject of considerable debate. They are suspected to be detrimental to the renal and hepatic functions, calcium balance, and insulin sensitivity. However, the long-term effects of a high-protein diet on a broad range of parameters have not been investigated. We studied the effects of a high-protein diet in rats over a period of 6 mo. Forty-eight Wistar male rats received either a normal-protein (NP: 14% protein) or high-protein (HP: 50% protein) diet. Detailed body composition, plasma hormones and nutrients, liver and kidney histopathology, hepatic markers of oxidative stress and detoxification, and the calcium balance were investigated. No major alterations of the liver and kidneys were found in HP rats, whereas NP rats exhibited massive hepatic steatosis. The calcium balance was unchanged, and detoxification markers (GSH and GST) were enhanced moderately in the HP group. In contrast, HP rats showed a sharp reduction in white adipose tissue and lower basal concentrations of triglycerides, glucose, leptin, and insulin. Our study suggests that the long-term consumption of an HP diet in male rats has no deleterious effects and could prevent metabolic syndrome.
Lipid-binding proteins and lipoprotein lipase activity in human skeletal muscle: influence of physical activity and gender
Authors: Kiens Bente , Roepstorff Carsten , Glatz Jan F. C. , Bonen Arend , Schjerling Peter , Knudsen Jens , Nielsen Jakob N.
Published: May 2004

The protein and mRNA levels of several muscle lipid-binding proteins and the activity and mRNA level of muscle lipoprotein lipase (mLPL) were investigated in healthy, nonobese, nontrained (NT), moderately trained, and endurance-trained (ET) women and men. FAT/CD36 protein level was 49% higher ( P < 0.05) in women than in men, irrespective of training status, whereas FAT/CD36 mRNA was only higher ( P < 0.05) in women than in men in NT subjects (85%). Plasma membrane-bound fatty acid binding protein (FABPpm) content was higher in ET men compared with all other groups, whereas training status did not affect FABPpmcontent in women. FABPpmmRNA was higher ( P < 0.05) in NT women than in ET women and NT men. mLPL activity was not different between gender, but mLPL mRNA was 160% higher ( P < 0.001) in women than in men. mLPL activity was 48% higher ( P < 0.05) in ET than in NT subjects, irrespective of gender, in accordance with 49% higher ( P < 0.05) mLPL mRNA in ET than in NT subjects. A 90-min exercise bout induced an increase ( P < 0.05) in FAT/CD36 mRNA (∼25%) and FABPpmmRNA (∼15%) levels in all groups. The present study demonstrated that, in the NT state, women had higher muscle mRNA levels of several proteins related to muscle lipid metabolism compared with men. In the ET state, only the gender difference in mLPL mRNA persisted. FAT/CD36 protein in muscle was higher in women than in men, irrespective of training status. These findings may help explain gender differences in lipid metabolism and, furthermore, suggest that the balance between gene transcription, translation, and possibly breakdown of several proteins in muscle lipid metabolism depend on gender.
Cholinergic Modulation of the Locomotor Network in the Lamprey Spinal Cord
Authors: Quinlan Katharina A. , Placas Peter G. , Buchanan James T.
Published: May 2004

Acetylcholine (ACh) was found here to be a strong modulator of swimming activity in the isolated spinal cord preparation of the adult lamprey ( Ichthyomyzon unicuspis). During fictive swimming induced with either d-glutamate or N-methyl-d-aspartate, addition of ACh (200 μM) significantly reduced the cycle period of ventral root bursts to 54%, intersegmental phase lag to 32%, and ventral root burst proportion to 80% of control levels. Effects of ACh were apparent at concentrations as low as 1 μM. Both nicotinic and muscarinic receptors are involved, in that application of either nicotinic or muscarinic agonists alone significantly reduced cycle period. There is sufficient endogenous ACh in the spinal cord to modulate ongoing fictive swimming, as shown by application of the cholinesterase inhibitor eserine (physostigmine). Eserine (20 μM) significantly reduced the cycle period to 78% and phase lag to 58% of control levels, and these effects were reversed with the addition of cholinergic blockers. Addition of only a nicotinic or muscarinic antagonist, mecamylamine (10 μM) or scopolamine (20 μM), respectively, to the spinal cord during fictive swimming produced significant increases in cycle period and phase lag, suggesting that both types of cholinergic receptors participate in endogenous cholinergic modulation. It is concluded that ACh is an endogenous modulator of the locomotor network in the lamprey spinal cord and that ACh may take part in the regulation of cycle period, intersegmental coupling, and ventral root burst duration.