bluuebunny/crossref_metadata_2025 huggingface dataset:
Contaminant containment using polymer gel barriers
Authors: Darwish M IM , Rowe R K , van der Maarel J RC , Pel L , Huinink H , Zitha P LJ
Published: February 2004

Polymer gels are well known in the oil industry, but their potential for use as barriers to contaminant transport has not previously received significant study. As a first step, this paper examines the potential for a polyelectrolyte gel to serve as a barrier to the migration of sodium chloride. Two series of tests are reported. These involve the use of hydrogen pulsed field gradient  nuclear magnetic resonance (HPFGNMR) to measure the self-diffusion on a microscopic scale and the use of magnetic resonance imaging (MRI) to monitor Na+ and H+ migration in the polymer gel with time. It is shown that the gel, which has a hydraulic conductivity of 2 × 1012 m/s, has a diffusion coefficient similar to that of compacted clay and greater sorption of Na+ than is typical for compacted clay.Key words: diffusion, contaminant, osmosis, gels, barriers.
Three-dimensional finite element nonlinear dynamic analysis of pile groups for lateral transient and seismic excitations
Authors: Maheshwari Bal Krishna , Truman Kevin Z , Naggar M Hesham El , Gould Phillip L
Published: February 2004

The effects of material nonlinearity of soil and separation at the soilpile interface on the dynamic behaviour of a single pile and pile groups are investigated. An advanced plasticity-based soil model, hierarchical single surface (HiSS), is incorporated in the finite element formulation. To simulate radiation effects, proper boundary conditions are used. The model and algorithm are verified with analytical results that are available for elastic and elastoplastic soil models. Analyses are performed for seismic excitation and for the load applied on the pile cap. For seismic analysis, both harmonic and transient excitations are considered. For loading on the pile cap, dynamic stiffness of the soilpile system is derived and the effect of nonlinearity is investigated. The effects of spacing between piles are investigated, and it was found that the effect of soil nonlinearity on the seismic response is very much dependent on the frequency of excitation. For the loading on a pile cap, the nonlinearity increases the response for most of the frequencies of excitation while decreasing the dynamic stiffness of the soilpile system.Key words: pile groups, plasticity, separation, dynamic stiffness, seismic response.
Hydraulic head in a clayey sand till over multiple timescales
Authors: Ostendorf David W , DeGroot Don J , Shelburne Wayne M , Mitchell Travis J
Published: February 2004

This paper presents an analysis of hydraulic head data measured every 2 h for 2 years in the leading edge of a drumlin that consists of weathered, brown clayey sand till and underlying unweathered gray clayey sand till. The brown till responds as an unconfined aquifer and acts as a boundary condition for the confined gray till aquifer. Analytical models are presented for interpretation of the hydraulic head data using annual, monthly, and daily timescales, for estimation of drumlin (landform) hydraulics and till (formation) properties. The annual average head data from open-standpipe piezometers calibrate drumlin hydraulics that feature steady radial flow in the brown till, because of its higher permeability (1.1 × 1013 m2) and the finite radius of the drumlin. The lower permeability (1.4 × 1015 m2) gray till has steady cylindrical flow with an appreciable downward gradient. Open-standpipe piezometer data are modeled at the monthly timescale to confirm the landform hydraulics and calibrate a brown till macroporosity of 0.016. The amplitude of periodic monthly head fluctuations increases towards the edge of the drumlin. Hydraulic head response to aperiodic storm events is significantly magnified by this macroporosity as measured by precipitation gages and buried pressure transducers. The storm data are modeled on a daily timescale to confirm the brown till macroporosity value estimated from the monthly data and to further elucidate gray till hydraulics. Compressibility delays and attenuates the groundwater mound, with a calibrated gray till compressibility of 3 × 109 Pa1. The calibrated models accurately recover drumlin flow fields with plausible property values of the clayey sand till, and accordingly should describe other sites with similar landforms and deposits.Key words: drumlins, till, hydraulics, compressibility, permeability, macroporosity, piezometer.
Compressive load response of granular piles reinforced with geogrids
Authors: Sharma Radhey S , Kumar BR Phani , Nagendra G
Published: February 2004

Results are presented from a series of tests performed to investigate improvement in load-carrying capacity and reduction in bulging of a granular pile in soft clay by geogrid reinforcement. The study revealed an increase in the load-carrying capacity of geogrid-reinforced piles. The engineering behaviour improved with an increase in the number of geogrids and a decrease in the spacing between them. The bulge diameter and bulge length decreased due to the incorporation of geogrid reinforcement.Key words: granular pile, geogrids, composite ground, load-carrying capacity, bulging.
Stress densification and its evaluation
Authors: Park Sung-Sik , Byrne Peter M
Published: February 2004

Stress densification occurs in natural soils as well as manmade embankments and physical model tests. Such densification can increase stability and liquefaction resistance. One-dimensional compression test data from eight sands were examined. From these data a stress densification equation is developed to estimate the density increase due to applied stress changes. It is found that stress densification can lead to erroneous conclusions if not taken into consideration when evaluating physical model test results.Key words: stress, densification, embankments, physical test.
Liquefaction flow of submarine slopes under partially undrained conditions: an effective stress approach
Authors: Atigh Ehsanollah , Byrne Peter M
Published: February 2004

The stability of submarine slopes is commonly assessed based on undrained soil response. Liquefaction flow may occur when pore-pressure rise in soil elements under constant shear stress causes a reduction in effective stresses. Recent experimental studies have shown that a small net flow of water into an element results in additional pore-pressure generation and further reduces its strength. As a result, soil elements can liquefy due to expansive volumetric strains that cannot be predicted by undrained analysis. Submarine deposits of the Fraser River delta are known to contain high concentrations of methane gas. Tidal variations can cause unequal pore-pressure generation with depth and time in these soils. Such changes reduce the effective stresses during low tides and may induce liquefaction flow of slopes due to partial drainage conditions. An effective stress approach based on an elasticplastic stressstrain relationship is presented to model liquefaction flow of sand. A fully coupled analysis is carried out to evaluate the behaviour of both saturated and gassy deposits of loose Fraser River sand and Ottawa sand. Triggering of liquefaction resulting in retrogressive flow slides is predicted for an unsaturated underwater slope similar to those observed near Sand Heads at the front of the Fraser delta.Key words: sand liquefaction, Fraser River delta, submarine slopes, flow slide, gassy sand, partial drainage.
Influence of loading path on the undrained behaviour of a medium loose sand
Authors: Gennaro V De , Canou J , Dupla J C , Benahmed N
Published: February 2004

The results of an experimental programme aimed at studying the undrained behaviour of Hostun sand are presented in this paper. Specific conditions concerning the initial relative density (medium loose arrangements) and the loading paths (compression and extension under monotonic and cyclic loadings) were considered in the test programme. Monotonic tests carried out in both drained and undrained conditions show a significant difference in behaviour between compression and extension. It is observed that, in undrained conditions, Hostun sand is weaker in extension than in compression. In compression, the material is stable (dilatant) and the phase-transformation state controls the mechanical behaviour. In extension, the experimental results show an unstable behaviour (contractant), with monotonic, liquefaction-induced instability in undrained conditions. The results of cyclic tests, carried out with one- and two-way stress reversals, show a good correlation with the results of monotonic tests. The loading path strongly influences the undrained mechanical behaviour of the sand, mainly by inducing liquefaction in extension. This situation suggests that differences in soil fabric, caused by the sample preparation technique (air pluviation), can influence the sand behaviour by inducing a significant contraction in extension. By further analysing the cyclic results, it is shown that, during unloading, the stress paths reflect the transverse isotropy (orthotropy) of the sand, with stiffer elastic characteristics in the vertical direction than in the horizontal direction.Key words: liquefaction, cyclic mobility, sands, triaxial test, anisotropy, loading path.
ADVANCED TECHNIQUE FOR DISTAL TENDON STUMP REPAIR OF A DIGIT
Authors: Xu Zhang
Published: February 2004

In this paper, we report on the advanced technique of distal tendon stump repair of a digit. A K-wire is used lengthwise to fix the distal and medium phalanxes, with the pull-out suture fixed on it. None of the cases repaired using this method was complicated with regional necrosis or tendon re-laceration. The advantages of advanced pull-out suture tied on a K-wire is that finger-tip pressure, which can lead to tissue necrosis, is avoided.
SEMI-CONSTRAINED TOTAL ELBOW ARTHROPLASTY IN CHINESE RHEUMATOID PATIENTS
Authors: Lo C. Y. , Lee K. B. , Wong C. K. , Chang Y. P.
Published: February 2004

Seventeen Coonrad-Morrey semi-constrained total elbow replacements were performed on 14 Chinese rheumatoid patients. The elbows were reviewed retrospectively after a mean follow-up of 36 months (range 12–89 months.) After the operation, all patients were satisfied and there was no pain in 15 elbows. There was no radiological sign of loosening in the implanted prostheses and bone graft was incorporated in 93% of primary elbow replacements. The Mayo Elbow Performance Score was improved from an average of 40 (range 20–75) to an average of 93 (range 65–100). The arc of flexion was improved from an average of 89° (range 0°–125°) to 104° (range 35°–125°). The sizes of implants can be predicted accurately by the planning template in only four elbows (24%) and there were early complications in seven elbows (41%), with one prosthesis removed because of deep infection.
BIOMECHANICAL EVALUATION OF PLATE OSTEOSYNTHESIS FOR AO TYPE C2 FRACTURE OF THE DISTAL RADIUS — A CADAVER STUDY
Authors: ur Rashid Haroon , Leung Frankie , Lu William , Fung Boris , Chow S. P.
Published: February 2004

An AO type C2 distal radius fracture was simulated in a cadaver model by creating a metaphyseal defect of 5 mm and an intra-articular defect of 2 mm. Five different methods of plate osteosynthesis were tested biomechanically in each of six fresh cadaveric hands. Biomechanical testing suggested that cement augmented plating plus screws in the distal fragment was the strongest. Dorsal and volar plating plus screws on both sides of the distal fragment had the same effect of restoring stiffness and load transmission pattern as fixation with double plating plus volar screws alone. Fixation with plating plus dorsal screws was significantly weaker than these three methods, and double buttress plating with no screws in the distal fragments was the weakest.
CLINICAL RESULTS OF EXTERNAL FIXATION FOR UNSTABLE COLLES' FRACTURES
Authors: Yamamoto Kengo , Masaoka Toshinori , Shishido Takaaki , Imakiire Atsuhiro
Published: February 2004

The objective of this study is to evaluate clinical and radiological outcomes of unstable or intra-articular Colles' fractures using the Pennig model of external fixation. The Pennig model of dynamic external fixation was used on 88 patients with 92 Colles' fractures. In 35 wrists, exercise was not performed during external fixation. In 57 wrists, exercise was initiated three weeks after surgery. Regarding radiological measurements, the degrees of volar tilt (VT), radial inclination (RI), radial length (RL) and ulnar variance (UV) were serially measured and evaluated. The clinical results were evaluated according to Sarminento's criteria. Favourable therapeutic outcomes (excellent and good) were obtained in 95.6% of the cases. However, when complicated by die-punch fractures, the outcome tended to be poorer. Postoperative re-displacement was often observed in patients over 50 years old. UV tended to increase and RL tended to decrease in the early motion group after the initiation of exercise. Neither VT nor RI significantly changed in either group during the postoperative observation period. Of patients in whom bone union of ulnar styloid fractures was not achieved, 32.2% complained of ulnar pain. Moreover, osteoarthritic changes were observed in two of 11 wrists with a step off of 1 to 2 mm or larger. In order to maintain the reduction position, it was important to determine the appropriate time for initiating exercise depending on the degree of fixation in each individual patients. The step off of the articular surface should be reduced to less than 1 mm and reductive fixation has to be performed additionally when complicated by ulnar styloid fractures.
CLINICAL RESULTS OF ARTHROLYSIS USING POSTERO-LATERAL APPROACH FOR POST-TRAUMATIC CONTRACTURE OF THE ELBOW JOINT
Authors: Yamamoto Kengo , Shishido Takaaki , Masaoka Toshinori , Imakiire Atsuhiro
Published: February 2004

We evaluated clinical results and postoperative problems associated with arthrolysis for post-traumatic contracture of the elbow joint. Arthrolysis was carried out in 47 elbows in 46 patients. Age at the time of arthroplasty ranged from 12 to 64 years (average 33 years). The period from time of injury to arthrolysis ranged from six months to six years (average 16 months). It was notable that scarring of the anterior capsule was pronounced in cases of long-term contracture. No apparent differences were observed in causes or age at operation, but the duration of preoperative symptoms and period of postoperative external fixation tended to affect the outcome. We conclude that arthrolysis is indicated irrespective of preoperative range of motion (ROM) and age, and that the surgery should be carried out before degeneration of cartilage and muscle atrophy progress. It was considered that long-term postoperative observation is also necessary, because in some cases there was postoperative progression of joint deformities, while in others there was decreased muscle strength after surgery.
DORSAL CAPSULODESIS AND LIGAMENTOPLASTY FOR CHRONIC PRE-DYNAMIC AND DYNAMIC SCAPHOLUNATE DISSOCIATION
Authors: Shih Jui-Tien , Lee Hung-Maan , Hou Yao-Tung , Horng Sheng-Tsi , Tan Chuan-Ming
Published: February 2004

Scapholunate (SL) instability is the most common cause of carpal instability. Pre-dynamic and dynamic type SL instability is difficult to diagnose and treat. This series reviews 17 soldiers with pre-dynamic or dynamic SL instability diagnosed by midcarpal arthroscopy and treated with dorsal capsulodesis and augmentation ligamentoplasty with partial dorsal radiocarpal (DRC) ligament procedure between 1997 and 2000. The sample included 14 males and three females. The dominant hand was involved in 15 patients. Moreover, the average patient age was 29.3 years (range 19–36 years). The diagnosis was based on clinical and arthroscopic criteria. Fifteen patients were followed up at our clinic regularly, with the follow-up period ranging from 12 to 39 months (mean 25.2 months). Fourteen patients had excellent or good results, and one patient had poor result based on Mayo Modified Wrist Score. Wrist motion in the flexion-extension plane loss averaged 18.4°. Grip force increased significantly following treatment, with improvement totaling 15% of normal side. No complications were found in this series. Consequently, dorsal capsulodesis and ligamentoplasty with partial DRC ligament is considered a valuable therapeutic option for cases of pre-dynamic and dynamic SL instability.
THE WEB: FRIEND OR FOE OF THE HAND SURGEON?
Authors: Sproule J. A. , Tansey C. , Burns B. , Fenelon G.
Published: February 2004

Healthcare information contained on the World Wide Web is not screened or regulated and claims may be unsubstantiated and misleading. The objective of this study was to evaluate the nature and quality of information on the Web in relation to hand surgery. Three search engines were assessed for information on three hand operations: carpal tunnel decompression, Dupuytren's release and trigger finger release. Websites were classified and evaluated for completeness, accuracy, accountability and reference to a reliable source of information. A total of 172 websites were examined. Although 85% contained accurate information, in 65% this information was incomplete. Eighty-seven per cent of websites were accountable for the information presented, but only 24% made references to reliable sources. Until an organised approach to website control is established, it is important for hand surgeons to emphasise to their patients that not everything they read is complete or accurate. Publicising sites known to be of high quality will promote safe browsing of the Web.
MULTIPLE SCHWANNOMAS OF THE MEDIAN NERVE: A CASE REPORT AND LITERATURE REVIEW
Authors: Aslam N. , Kerr G.
Published: February 2004

We report a case of multiple schwannomas of the median nerve. Multiple schwannomas can be difficult to diagnose on clinical grounds and can be mistakenly diagnosed as carpal tunnel syndrome or ganglia as in our case. Nerve conduction studies helped locate non-visible tumours. Magnetic resonance imaging (MRI) is useful in the preoperative planning of these tumours. The appearances on scanning however can be sometimes confused for ganglia as in this case. Intraneural dissection of the schwannomas was carried out and the pathology is described.
ENDOSCOPIC CARPAL TUNNEL RELEASE AND CONGENITAL ANOMALIES OF THE MEDIAN NERVE
Authors: Cavallo Andrew V. , Slattery Philip G. , Barton Richard J.
Published: February 2004

Endoscopic release has been shown to be a safe and effective means of carpal tunnel decompression. The surgeon needs to be aware of the variations in the anatomy of the median nerve in order to minimise the risk of nerve injury. In this series of 748 endoscopic carpal tunnel releases, six were found to have variations in the median nerve anatomy, in two patients conversion to open release was necessary.
TRICHILEMMAL CYST IN THE PULP OF THE INDEX FINGER: A CASE REPORT
Authors: Ikegami Takeshi , Kameyama Makoto , Orikasa Hideki , Yamazaki Kazuto
Published: February 2004

We reported a case of trichilemmal cyst in the pulp of the index finger. Histopathological features and unusual MR images are discussed.
TREATMENT OF FINGERTIPS AMPUTATION USING THE HIRASE TECHNIQUE
Authors: Adani R. , Marcoccio I. , Tarallo L.
Published: February 2004

The management of very distal finger amputations when the amputated part is saved is still difficult and controversial. Both re-attachment of the amputated portion as a composite graft and microvascular anastomosis can fail in this distal location. Replantation is, in fact, associated with certain problems, such as technical difficulty, risk of failure because of the poor venous drainage, and costs. With the exception of children, amputations at the level of the lunula poorly survive direct re-attachment. Hirase has described a new replantation model without vascular anastomosis and used ice water and aluminium foil to enhance survival of the composite graft. Cooling the entire recipient site retards cellular degeneration in the graft until neovascularisation occurs. The present authors applied this method to seven cases in which a digit had been amputated between the tip and the lunula. In four cases the method proved to be completely successful, whereas in two an area of tip necrosis was observed. The Hirase method has proven to be a simple and reliable surgical technique for fingertip re-attachment.
DEFECTS ON THE DORSUM OF THE HAND — THE POSTERIOR INTEROSSEOUS FLAP AND ITS ALTERNATIVES
Authors: Koch H. , Kursumovic A. , Hubmer M. , Seibert F. J. , Haas F. , Scharnagl E.
Published: February 2004

There are conditions that preclude the use of the posterior interosseous flap for reconstruction of the dorsum of the hand. Based on a series of 34 cases, these conditions are outlined and alternative solutions discussed.

The posterior interosseous flap was employed for closure in 30 cases. In four cases different methods were used due to severe trauma to the wrist and distal forearm with potential impairment of the pedicle, a complex defect requiring a composite flap and an anatomical variation. Thin free flaps were employed alternatively. All flaps survived but there was marginal flap necrosis in two posterior interosseous flaps.

The posterior interosseous flap proved its usefulness and reliability in reconstruction of the hand in this series. In four cases, free lateral arm and temporoparietal fascial flaps were employed. Flaps based on the main vessels of the forearm were not used due to their significant donor site morbidity.
INTERCALARY NON-VASCULARISED TOE PHALANX TRANSPLANTATION FOR SHORT FINGER-TYPE SYMBRACHYDACTYLY
Authors: Kanauchi Yumiko , Takahara Masatoshi , Ogino Toshihiko , Kashiwa Hideo , Ishigaki Daisuke
Published: February 2004

A two-year-old boy with short finger-type symbrachydactyly involving the index, middle, and ring fingers was treated with intercalary nonvascularised toe phalanx transplantation into the middle finger to obtain stability of the middle finger before syndactyly release. He underwent syndactyly release one year after the transplantation. Two years after the transplantation, the clinical result was satisfactory, although X-ray showed fibrous union between the transplanted phalanx and the host phalanx. Intercalary nonvascularised toe phalanx transplantation is one of the way of stabilising a finger after syndactyly release.
ULNAR NERVE COMPRESSION AT GUYON'S CANAL BY AN ANOMALOUS ABDUCTOR DIGITI MINIMI MUSCLE: THE ROLE OF ULTRASOUND IN CLINICAL DIAGNOSIS
Authors: Harvie Paul , Patel Neel , Ostlere Simon J.
Published: February 2004

Anomalous variations of abductor digiti minimi are commonly found at Guyon's canal but rarely cause ulnar nerve compression. We report such a case with particular emphasis on the effectiveness of ultrasound to detect and delineate anatomical structures in this region.
SURGERY FOR TRIGGER FINGER
Authors: Finsen Vilhjalmur , Hagen Solfrid
Published: February 2004

One of the two English-language reports on the results of surgery for trigger finger reported frequent complications and poor results and the other, few complications and good results. We reviewed 72 patients with 84 operated digits 8½ (7–11) years after surgery. One patient was re-operated because of persisting symptoms, and another had a moderate recurrence. There were two transitory neuropraxias, but no permanent nerve damage could be detected. It was concluded that in cases where symptoms persist after steroid injection, surgery may be recommended. However, the risk of troublesome complications, even after this minor operation, should be borne in mind.
ULTRASONOGRAPHY FOR THE INTEROSSEOUS MEMBRANE OF THE FOREARM
Authors: Matsuoka Juli , Beppu Moroe , Nakajima Hiroshi , Aoki Haruhito
Published: February 2004

The ability to improve the technique for an accurate clinical diagnosis of the injury of interosseous membrane of the forearm (IOM) associated with forearm fractures and dislocations is important for its treatment and prognosis. Ultrasound examination of the IOM in 46 forearms from 18 normal volunteers, five patients with restricted forearm pronation and supination, and two preoperative cases was performed to determine the usefulness and reproductivity of this examination. The intact IOM was observed as a continuous, slightly convex anteriorly and hyperechoic structure between the radius and ulna with both transverse and longitudinal views. IOMs with histories of forearm injuries were distinguished by the findings, which demonstrated a loss of continuity and were seen as hypoechoic traces from the others. This study confirmed that it is possible to trace the entire IOM and to detect differences between intact and disrupted IOMs with transverse and longitudinal views.
AN ANATOMICAL STUDY OF THE LIGAMENTS OF THE ULNAR COMPARTMENT OF THE WRIST
Authors: Sasao Saburo , Beppu Moroe , Kihara Hitoshi , Hirata Kazuaki , Takagi Masayuki
Published: February 2004

The ligamentous structures of the triangular fibrocartilage complex (TFCC) and their attachments were examined anatomically and histologically using fresh and embalmed cadavers. The TFCC was observed to have a three-dimensional structure consisting of three palmar ligaments — the short radiolunate (SRL), ulnolunate (UL), and ulnotriquetral (UT) ligaments. In addition, the attachment site of the ulnocarpal ligament (UC), which had been previously unknown, was identified. The dorsal components of the TFCC have been previously reported to consist solely of the extensor carpi ulnaris (ECU) subsheath; however, the ligamentous components running from the ulnar styloid process to the triquetrum were found at a layer deeper than the floor of the ECU subsheath.

The UC has been reported previously as a two-dimensional structure, but there has been some disagreement as to its attachment sites.2–6,14,15It is suggested that the dorsal UT ligament should be considered as a separate ligament, based on its different direction and distal attachment site as compared with those of the ulnar collateral ligament (UCL) and ECU subsheath.
Sleep enhances nocturnal plasma ghrelin levels in healthy subjects
Authors: Dzaja Andrea , Dalal Mira A. , Himmerich Hubertus , Uhr Manfred , Pollmächer Thomas , Schuld Andreas
Published: February 2004

Ghrelin, an endogenous ligand of the growth hormone secretagogue receptor, has been shown to promote slow-wave sleep (SWS, non-REM sleep stages 3 and 4). Plasma levels of ghrelin are dependent on food intake and increase in sleeping subjects during the early part of the night. It is unknown whether sleep itself affects ghrelin levels or whether circadian networks are involved. Therefore, we studied the effect of sleep deprivation on nocturnal ghrelin secretion. In healthy male volunteers, plasma levels of ghrelin, cortisol, and human growth hormone (hGH) were measured during two experimental sessions of 24 h each: once when the subjects were allowed to sleep between 2300 and 0700 and once when they were kept awake throughout the night. During sleep, ghrelin levels increased during the early part of the night and decreased in the morning. This nocturnal increase was blunted during sleep deprivation, and ghrelin levels increased only slightly until the early morning. Ghrelin secretion during the first hours of sleep correlated positively with peak hGH concentrations. We conclude that the nocturnal increase in ghrelin levels is more likely to be caused by sleep-associated processes than by circadian influences. During the first hours of sleep, ghrelin might promote sleep-associated hGH secretion and contribute to the promotion of SWS.
Endothelial nitric oxide synthase is protective in the initiation of caerulein-induced acute pancreatitis in mice
Authors: DiMagno Matthew J. , Williams John A. , Hao Yibai , Ernst Stephen A. , Owyang Chung
Published: February 2004

The effect of inhibiting nitric oxide (NO) synthase (NOS) or enhancing NO on the course of acute pancreatitis (AP) is controversial, in part because three NOS isoforms exist: neuronal (nNOS), endothelial (eNOS), and inducible (iNOS). We investigated whether inhibition or selective gene deletion of NOS isoforms modified the initiation phase of caerulein-induced AP in mice and explored whether this affected pancreatic microvascular blood flow (PMBF). We investigated the effects of nonspecific NOS inhibition with Nω-nitro-l-arginine (l-NNA; 10 mg/kg ip) or targeted deletion of eNOS, nNOS, or iNOS genes on the initiation phase of caerulein-induced AP in mice using in vivo and in vitro models. Western blot analysis was performed to assess eNOS phosphorylation status, an indicator of enzyme activity, and microsphere studies were used to measure PMBF. l-NNA and eNOS deletion, but not nNOS or iNOS deletion, increased pancreatic trypsin activity and serum lipase during the initiation phase of in vivo caerulein-induced AP. l-NNA and eNOS did not affect trypsin activity in caerulein-hyperstimulated isolated acini, suggesting that nonacinar events mediate the effect of NOS blockade in vivo. The initiation phase of AP in wild-type mice was associated with eNOS Thr495 residue dephosphorylation, which accompanies eNOS activation, and a 178% increase in PMBF; these effects were absent in eNOS-deleted mice. Thus eNOS is the main isoform influencing the initiation of caerulein-induced AP. eNOS-derived NO exerts a protective effect through actions on nonacinar cell types, most likely endothelial cells, to produce greater PMBF.
Alterations of adenylyl cyclase and G proteins in aortocaval shunt-induced heart failure
Authors: Wang Xi , Sentex Emmanuelle , Chapman Donald , Dhalla Naranjan S.
Published: February 2004

Unlike most other experimental models of congestive heart failure, the volume overload model induced by aortocaval shunt (AVS) in rats was found to exhibit enhanced β-adrenoceptor (β-AR) signaling. To study whether the adenylyl cyclase (AC)-G protein system is involved in such a change, we examined cardiac AC activity and protein content as well as Gsα and Giα activities, protein contents, and mRNA levels in both left (LV) and right (RV) ventricles at the failing stage (16 wk after surgery). Basal and forskolin-stimulated AC activities were significantly increased in both LV and RV from the failing hearts; this change was associated with an upregulation of type V/VI AC protein. In contrast to 5′-guanylyl imidodiphosphate and NaF, the stimulatory effect of isoproterenol on AC was increased in the failing heart. Although Gsα and Giα protein contents in the failing hearts were not altered, the mRNA level for Gsα was decreased by 20% and that for Giα was increased by 20%. In addition, the activity of Gsα, but not Giα, as assessed by toxin-catalyzed ADP ribosylation, was significantly decreased in the failing heart. Losartan and imidapril treatments improved cardiac function and attenuated alterations in mRNA levels for Gsα and Giα proteins, as well as Gsα activity, without affecting changes in AC protein content or activities in heart failure due to volume overload. These data suggest that increased AC activity may contribute to the enhanced β-AR signaling in the AVS model of heart failure, whereas alterations in gene expression for G proteins may be of an adaptive nature at this stage of heart failure.
Effects of chronic psychosocial stress on cardiac autonomic responsiveness and myocardial structure in mice
Authors: Costoli Tania , Bartolomucci Alessandro , Graiani Gallia , Stilli Donatella , Laviola Giovanni , Sgoifo Andrea
Published: February 2004

Repeated single exposures to social stressors induce robust shifts of cardiac sympathovagal balance toward sympathetic dominance both during and after each agonistic interaction. However, little evidence is available regarding possible persistent pathophysiological changes due to chronic social challenge. In this study, male CD-1 mice ( n = 14) were implanted with a radiotelemetry system for electrocardiographic recordings. We assessed the effects of chronic psychosocial stress (15-day sensory contact with a dominant animal and daily 5-min defeat episodes) on 1) sympathovagal responsiveness to each defeat episode, as measured via time-domain indexes of heart rate variability (R-R interval, standard deviation of R-R interval, and root mean square of successive R-R interval differences), 2) circadian rhythmicity of heart rate across the chronic challenge (night phase, day phase, and rhythm amplitude values), and 3) amount of myocardial structural damage (volume fraction, density, and extension of fibrosis). This study indicated that there was habituation of acute cardiac autonomic responsiveness, i.e., the shift of sympathovagal balance toward sympathetic dominance was significantly reduced across repeated defeat episodes. Moreover, animals exhibited significant changes in heart rate rhythmicity, i.e., increments in day and night values and reductions in the rhythm amplitude, but these were limited to the first 5 days of chronic psychosocial stress. The volume fraction of fibrosis was sixfold larger than in control animals, because of the appearance of many microscopic scarrings. In summary, although mice appeared to adapt to chronic psychosocial stress in terms of acute cardiovascular responsiveness and heart rate rhythmicity, structural alterations occurred at the myocardial level.
Flow-dependent increase of ICAM-1 on saphenous vein endothelium is sensitive to apamin
Authors: Sultan Sabena , Gosling Martin , Abu-Hayyeh Shadi , Carey Nessa , Powell Janet T.
Published: February 2004

The potassium channel blocker tetraethylammonium blocks the flow-induced increase in endothelial ICAM-1. We have investigated the subtype of potassium channel that modulates flow-induced increased expression of ICAM-1 on saphenous vein endothelium. Cultured human saphenous vein endothelial cells (HSVECs) or intact saphenous veins were perfused at fixed low and high flows in a laminar shear chamber or flow rig, respectively, in the presence or absence of potassium channel blockers. Expression of K+ channels and endothelial ICAM-1 was measured by real-time polymerase chain reaction and/or immunoassays. In HSVECs, the application of 0.8 N/m2 (8 dyn/cm2) shear stress resulted in a two- to fourfold increase in cellular ICAM-1 within 6 h ( P < 0.001). In intact vein a similar shear stress, with pulsatile arterial pressure, resulted in a twofold increase in endothelial ICAM-1/CD31 staining area within 1.5 h ( P < 0.001). Both increases in ICAM-1 were blocked by inclusion of 100 nM apamin in the vein perfusate, whereas other K+ channel blockers were less effective. Two subtypes of small conductance Ca2+-activated K+ channel (selectively blocked by apamin) were expressed in HSVECs and vein endothelium (SK3>SK2). Apamin blocked the upregulation of ICAM-1 on saphenous vein endothelium in response to increased flow to implicate small conductance Ca2+-activated K+ channels in shear stress/flow-mediated signaling pathways.
Effects of neuronal norepinephrine uptake blockade on baroreflex neural and peripheral arc transfer characteristics
Authors: Kawada Toru , Miyamoto Tadayoshi , Uemura Kazunori , Kashihara Koji , Kamiya Atsunori , Sugimachi Masaru , Sunagawa Kenji
Published: February 2004

Neuronal uptake is the most important mechanism by which norepinephrine (NE) is removed from the synaptic clefts at sympathetic nerve terminals. We examined the effects of neuronal NE uptake blockade on the dynamic sympathetic regulation of the arterial baroreflex because dynamic characteristics are important for understanding the system behavior in response to exogenous disturbance. We perturbed intracarotid sinus pressure (CSP) according to a binary white noise sequence in anesthetized rabbits, while recording cardiac sympathetic nerve activity (SNA), arterial pressure (AP), and heart rate (HR). Intravenous administration of desipramine (1 mg/kg) decreased the normalized gain of the neural arc transfer function from CSP to SNA relative to untreated control (1.03 ± 0.09 vs. 0.60 ± 0.08 AU/mmHg, mean ± SE, P < 0.01) but did not affect that of the peripheral arc transfer function from SNA to AP (1.10 ± 0.05 vs. 1.08 ± 0.10 mmHg/AU). The normalized gain of the transfer function from SNA to HR was unaffected (1.01 ± 0.04 vs. 1.09 ± 0.12 beats·min−1·AU−1). Desipramine decreased the natural frequency of the transfer function from SNA to AP by 28.7 ± 7.0% (0.046 ± 0.007 vs. 0.031 ± 0.002 Hz, P < 0.05) and that of the transfer function from SNA to HR by 64.4 ± 2.2% (0.071 ± 0.003 vs. 0.025 ± 0.002 Hz, P < 0.01). In conclusion, neuronal NE uptake blockade by intravenous desipramine administration reduced the total buffering capacity of the arterial baroreflex mainly through its action on the neural arc. The differential effects of neuronal NE uptake blockade on the dynamic AP and HR responses to SNA may provide clues for understanding the complex pathophysiology of cardiovascular diseases associated with neuronal NE uptake deficiency.
Homeostatic regulation of sleep in arrhythmic Siberian hamsters
Authors: Larkin Jennie E. , Yokogawa Tohei , Heller H. Craig , Franken Paul , Ruby Norman F.
Published: February 2004

Sleep is regulated by independent yet interacting circadian and homeostatic processes. The present study used a novel approach to study sleep homeostasis in the absence of circadian influences by exposing Siberian hamsters to a simple phase delay of the photocycle to make them arrhythmic. Because these hamsters lacked any circadian organization, their sleep homeostasis could be studied in the absence of circadian interactions. Control animals retained circadian rhythmicity after the phase shift and re-entrained to the phase-shifted photocycle. These animals displayed robust daily sleep-wake rhythms with consolidated sleep during the light phase beginning about 1 h after light onset. This marked sleep-wake pattern was circadian in that it persisted in constant darkness. The distribution of sleep in the arrhythmic hamsters over 24 h was similar to that in the light phase of rhythmic animals. Therefore, daily sleep amounts were higher in arrhythmic animals compared with rhythmic ones. During 2- and 6-h sleep deprivations (SD), it was more difficult to keep arrhythmic hamsters awake than it was for rhythmic hamsters. Because the arrhythmic animals obtained more non-rapid eye movement sleep (NREMS) during the SD, they showed a diminished compensatory response in NREMS EEG slow-wave activity during recovery sleep. When amounts of sleep during the SD were taken into account, there were no differences in sleep homeostasis between experimental and control hamsters. Thus loss of circadian control did not alter the homeostatic response to SD. This supports the view that circadian and homeostatic influences on sleep regulation are independent processes.
Nasal cavity dimensions in guinea pig and rat measured by acoustic rhinometry and fluid-displacement method
Authors: Straszek Sune P. , Pedersen Ole F.
Published: February 2004

The purpose of the study was to measure nasal passageway dimensions in guinea pigs and rats by use of acoustic rhinometry (AR) and by a previously described fluid-displacement method (FDM) (Straszek SP, Taagehoej F, Graff S, and Pedersen OF. J Appl Physiol 95: 635–642, 2003) to investigate the potential of AR in pharmacological research with these animals. We measured the area-distance relationships by AR of nasal cavities postmortem in five guinea pigs (Duncan Hartley, 400 g) and five rats (Wistar, 250 g) by using custom-made equipment scaled for the purpose. Nosepieces were made from plastic pipette tips and either inserted into or glued onto the nostrils. We used liquid perfluorocarbon in the fluid-displacement study, and it was carried out subsequent to the acoustic measurements. We found for guinea pigs that AR measured a mean volume of 98 mm3 (95–100 mm3) (mean and 95% confidence interval) of the first 2 cm of the cavity. FDM measured a mean volume of 146 mm3 (117–175 mm3), meaning that AR only measured 70% (50–90) of the volume by FDM. For rats, the volume from 0 to 2 cm was 58 mm3 (55–61 mm3) by AR and 73 mm3 (60–87 mm3) by FDM, resulting in AR only measuring 83% (66–100%) of volume by FDM (see Table 2 ). We conclude that absolute nasal cavity dimensions are underestimated by AR in guinea pigs and rats. This does not preclude that relative changes may be correctly measured. In vivo trials with AR using rats have not yet been published. The FDM is possibly the most accurate alternative to AR for measurements of the nasal cavity geometry in small laboratory animals, but it can only be used postmortem.
Differential effects of ozone on airway and tissue mechanics in obese mice
Authors: Rivera-Sanchez Y. M. , Johnston R. A. , Schwartzman I. N. , Valone J. , Silverman E. S. , Fredberg J. J. , Shore S. A.
Published: February 2004

Obesity is an important risk factor for asthma. We recently reported increased ozone (O3)-induced hyperresponsiveness to methacholine in obese mice (Shore SA, Rivera-Sanchez YM, Schwartzman IN, and Johnston RA. J Appl Physiol 95: 938–945, 2003). The purpose of this study was to determine whether this increased hyperresponsiveness is the result of changes in the airways, the lung tissue, or both. To that end, we examined the effect of O3 (2 parts/million for 3 h) on methacholine-induced changes in lung mechanics with the use of a forced oscillation technique in wild-type C57BL/6J mice and mice obese because of a genetic deficiency in leptin ( ob/ob mice). In ob/ob mice, O3 increased baseline values for all parameters measured in the study: airway resistance (Raw), lung tissue resistance (Rtis), lung tissue damping (G) and elastance (H), and lung hysteresivity (η). In contrast, no effect of O3 on baseline mechanics was observed in wild-type mice. O3 exposure significantly increased Raw, Rtis, lung resistance (Rl), G, H, and η responses to methacholine in both groups of mice. For G, Rtis, and Rl there was a significant effect of obesity on the response to O3. Our results demonstrate that both airways and lung tissue contribute to the hyperresponsiveness that occurs after O3 exposure in wild-type mice. Our results also demonstrate that changes in the lung tissue rather than the airways account for the amplification of O3-induced hyperresponsiveness observed in obese mice.
Pyruvate dehydrogenase activation and kinase expression in human skeletal muscle during fasting
Authors: Spriet Lawrence L. , Tunstall Rebecca J. , Watt Matthew J. , Mehan Kate A. , Hargreaves Mark , Cameron-Smith David
Published: February 2004

Fasting forces adaptive changes in whole body and skeletal muscle metabolism that increase fat oxidation and decrease the oxidation of carbohydrate. We tested the hypothesis that 40 h of fasting would decrease pyruvate dehydrogenase (PDH) activity and increase PDH kinase (PDK) isoform mRNA expression in human skeletal muscle. The putative transcriptional activators of PDK isozymes, peroxisome proliferator-activated receptor-α (PPAR-α) protein, and forkhead homolog in rhabdomyosarcoma (FKHR) mRNA were also measured. Eleven healthy adults fasted after a standard meal (25% fat, 60% carbohydrate, 15% protein) with blood and skeletal muscle samples taken at 3, 15, and 40 h postprandial. Fasting increased plasma free fatty acid, glycerol, and β-hydroxybutyrate concentrations and decreased glucose and insulin concentrations. PDH activity decreased from 0.88 ± 0.11 mmol acetyl-CoA · min-1 · kg wet muscle wt-1 at 3 h to 0.62 ± 0.10 ( P = not significant) and 0.39 ± 0.06 ( P < 0.05) mmol · min-1 · kg wet mass-1 after 15 and 40 h of fasting. Although all four PDK isoforms were expressed in human skeletal muscle, PDK-2 and -4 mRNA were the most abundant. PDK-1 and -3 mRNA abundance was ∼1 and 15% of the PDK-2 and -4 levels, respectively. The 40-h fast had no effect on PDK-1, -2, and -3 mRNA expression. PDK-4 mRNA was significantly increased ∼3-fold after 15 h and ∼14-fold after 40 h of fasting. Skeletal muscle PPAR-α protein and FKHR mRNA abundance were unaffected by the fast. The results suggest that decreased PDH activation after 40 h of fasting may have been a function of the large increase in PDK-4 mRNA expression and possible subsequent increase in PDK protein and activity. The changes in PDK-4 expression and PDH activity did not coincide with increases in the transcriptional activators PPAR-α and FKHR.
Dynamics of Olfactory Bulb Input and Output Activity During Odor Stimulation in Zebrafish
Authors: Friedrich Rainer W. , Laurent Gilles
Published: February 2004

The processing of odor-evoked activity in the olfactory bulb (OB) of zebrafish was studied by extracellular single unit recordings from the input and output neurons, i.e., olfactory receptor neurons (ORNs) and mitral cells (MCs), respectively. A panel of 16 natural amino acid odors was used as stimuli. Responses of MCs, but not ORNs, changed profoundly during the first few hundred milliseconds after response onset. In MCs, but not ORNs, the total evoked excitatory activity in the population was initially odordependent but subsequently converged to a common level. Hence, the overall population activity is regulated by network interactions in the OB. The tuning widths of both ORN and MC response profiles were similar and, on average, stable over time. However, when analyzed for individual neurons, MC response profiles could sharpen (excitatory response to fewer odors) or broaden (excitatory response to more odors), whereas ORN response profiles remained nearly unchanged. Several observations indicate that dynamic inhibition plays an important role in this remodeling. Finally, the reliability of odor identification based on MC population activity patterns improved over time, whereas odor identification based on ORN activity patterns was most reliable early in the odor response. These results demonstrate that several properties of MC, but not ORN, activity change during the initial phase of the odor response with important consequences for odor-encoding activity patterns. Furthermore, our data indicate that inhibitory interactions in the OB are important in dynamically shaping the activity of OB output neurons.
Multivariate Fréchet copulas and conditional value‐at‐risk
Authors: Hürlimann Werner
Published: February 2004

Based on the method of copulas, we construct a parametric family of multivariate distributions using mixtures of independent conditional distributions. The new family of multivariate copulas is a convex combination of products of independent and comonotone
subcopulas. It fulfills the four most desirable properties that a multivariate statistical model should satisfy. In particular, the bivariate margins belong to a simple but flexible one‐parameter family of bivariate copulas, called linear Spearman copula, which
is similar but not identical to the convex family of Fréchet. It is shown that the distribution and stop‐loss transform of dependent sums from this multivariate family can be evaluated using explicit integral formulas, and that these dependent sums are bounded in convex order between the corresponding independent and comonotone sums. The model is applied to the evaluation of the economic risk capital for a portfolio of risks using conditional value‐at‐risk measures. A multivariate conditional value‐at‐risk vector measure is considered. Its components coincide for the constructed multivariate copula with the conditional value‐at‐risk measures of the risk components of the portfolio. This yields a “fair” risk allocation in the sense that each risk component becomes allocated to its coherent conditional value‐at‐risk.
Powersum formula for differential resolvents
Authors: Nahay John Michael
Published: February 2004

We will prove that we can specialize the indeterminate α in a linear differential α‐resolvent of a univariate polynomial over a differential field of characteristic zero to an integer q to obtain a q‐resolvent. We use this idea to obtain a formula, known as the powersum formula, for the terms of the α‐resolvent. Finally, we use the powersum formula to rediscover Cockle′s differential resolvent of a cubic trinomial.