bluuebunny/crossref_metadata_2025 huggingface dataset:
Relationship between file size and stiffness of nickel titanium instruments
Authors: Camps J. J. , Pertot W. J. , Levallois B.
Published: April 2006

Abstract – The purpose of this study was to evaluate the relationship existing between file size and stiffness for 3 endodontic files made of nickel titanium. Three groups of instruments with different cross‐sections were tested: a triangular cross‐section, a square cross‐section and a modified triangular cross‐section. The instruments were tested from size 15 to size 40 or 60 according to ANSI/ADA specification n°28 for binding moment evaluation. There was a statistically significant difference between the 3 groups: the square cross‐section K files presented a larger bending moment than the triangular cross‐section K files, which presented a larger bending moment than the modified cross‐section K files. Like the stainless steel instrumens, there was an exponential relationship between file size and bending moment for triangular and square cross‐section K files, but a linear relationship between file size and bending moment for the files with a modified triangular cross‐section.
Effect of palatal injections on pulpal blood flow in premolars
Authors: Premdas C. E. , Pitt Ford T. R.
Published: April 2006

Abstract – The effect of palatal infiltration injections using 2% lignocaine hydrochloride with 1:80,000 adrenaline was evaluated for sound maxillary first premolar teeth. The influence of the injections on pulpal blood flow and local anaesthesia was investigated. Ten human volunteers were given the following injections on different days: 1 ml palatal infiltration; 1 ml buccal infiltration; 1 ml palatal and 1 ml buccal infiltration; and 2 ml buccal infiltration. The blood flow was observed with a laser Doppler flowmeter with the probes held against the buccal surfaces of the teeth by a splint. Blood flow was recorded digitally on a computer in machine units. Pulpal anaesthesia was assessed using a monopolar electric pulp tester. All injections significantly reduced blood flow from baseline levels (p < 0.05). The 1‐ml palatal injection produced a significantly longer period of reduced blood flow (mean 40 min) compared with the other injections (p < 0.05). The duration of blood flow reduction was shorter than the duration of pulpal anaesthesia for every injection. Only seven out of 10 palatal injections achieved pulpal anaesthesia. The 2‐ml buccal injection and the combined buccal and palatal injections produced significantly longer anaesthesia than the 1‐ml buccal injection (p < 0.05).
Splints made of wire and composite: an investigation of lateral tooth mobility in vivo
Authors: Ebeleseder K. A. , Glockner K. , Pertl C. , Städtler P.
Published: April 2006

Abstract In 103 posttraumatic splints, lateral tooth mobility was measured with Periotest immediately before and after the routine splint removal. The splints were made of composite resin and an 0.017×0.025″ orthodontic steel wire. 481 teeth were measured. A statistic evaluation revealed that the immobilisation effect did not exceed normal tooth firmness. Fixation to one neighbouring tooth had less effect than fixation to two. Adjacent tooth gaps reduced the effect. Splint extensions had no influence. With the use of the Periotest device, more than 50% of all teeth with a true mobility of 20 Periotest‐units or more were detectable as mobile in spite of the fixed splint.
Relation between incisal overjet and traumatic injury: a case control study
Authors: Stokes A. N. , Loh T. , Teo C. S. , Bagramian R. A.
Published: April 2006

Abstract Most previous studies have shown the prevalence of traumatic dental injuries in anterior teeth to increase with increasing overjet. This study identified 36 Singapore schoolchildren, age 7–18 years, from a clinic population of 11,179, who had suffered dental trauma while playing contact or collision sports. A case control group of 36 children, matched for age, sex, race and sporting activities, but who had not suffered dental trauma, was selected from the same clinic population. Both groups were examined and the nature of injuries received, together with overjet measured to the nearest 0.5 mm were determined. The mean overjet for the trauma group was 3.42±1.45 mm and for the injured group 3.42±1.33 mm. These means were not statistically different (p = 1.00), neither did the distribution of overjet between the groups differ. These data were not in accord with the majority of studies correlating incisal overjet and dental trauma, and they suggested that overjet was not a positive correlate with traumatic dental injury in Singapore schoolchildren.
Observation of bacteria and fungi in infected root canals and dentinal tubules by SEM
Authors: Sen B. H. , Piskin B. , Demirci T.
Published: April 2006

Abstract The aim of this study was to observe the root canal flora and possible penetration of microorganisms into dentinal tubules in teeth with necrotic pulps. Ten infected maxillary and mandibular molars with periapical lesions were extracted and fixed in 2.5% phosphate‐buffered glutaraldehyde solution for nine days. After separation from the crowns, longitudinal grooves were cut in the roots, and they were split into two halves. The specimens were prepared for SEM. The root canals and the dentinal tubules of the fractured dentin were scanned systematically from the cervical to the apical area of the root. Cocci and rods were seen in 6 specimens. Penetration of bacteria into the dentinal tubules ranged from 10 to 150 μm. In 4 specimens, the root canals were heavily invaded by yeasts. The antimicrobial effect of routinely used endodontic disinfectants also on yeasts may be considered in persistent root canal infections.
Cleaning of endodontic instruments before use
Authors: Zmener O. , Speilberg C.
Published: April 2006

Abstract In this study, 120 new K‐files and Hedström files from 3 different manufacturers were examined for surface debris with the scanning electron microscope. The instruments were examined immediately upon removal from their original packages. A second examination of the instruments was performed after they were cleansed in an ultrasonic bath. None of the studied instruments were free of metallic spurs or foreign particles as received from the manufacturers. The ultrasonic bath used together with a cleanser solution appeared to be an effective method to minimize the surface impurities from the manufacturing process prior to use in patients.
Endodontic measurements in digital radiographs acquired by a photostimulable storage phosphor system
Authors: Borg E. , Gröndahl H‐G.
Published: April 2006

Abstract Digora® is a newly developed digital system for intraoral radiography utilizing photostimulable storage phosphor image plates. The aim was to test the <quality of the system in respect to the visibility of endodontic files and root apices at different exposures. In teeth from live dry mandibular jaw sections, Hedströme files no. 15 was placed with the file lip at varying distances from the apex. The specimens were covered with soil tissue equivalent material and placed behind a 2‐cm thick polymethyl methacrylate cylinder filled with water. Distance from focus to image plate was 30 cm. Exposures were made at 60 kV and 7 am at 7 timer settings from 16 ms to 1000 ms in increments. All images were viewed from the monitor by each of 8 observers allowed to use available contrast enhancement facilities to obtain subjectively good image quality. Utilizing built‐in measurement functions, distances from file tip and root apex, respectively, to a reference line were measured in 0.1 mm. for measurements between file tip and reference line, and root apex and reference line, there was no statistically significant difference between measurements made all the lowest exposure, compared to the second lowest exposure but there was a statistically significant difference compared to the 5 highest. Measurements al the second lowest exposure were not significantly different from those obtained al the 5 highest exposures. Interobserver variability expressed as standard deviation between observers showed the largest value for measurements obtained at the lowest exposure. The mean observed distances between the lip of the file and the root apex were calculated and showed no statistically significant difference between different exposures. we concluded that the Digora intraoral image plate system provided reliable endodontie measurements even al very low exposures.
Young's modulus of warm and cold gutta‐percha
Authors: Camps J. J. , Pertot W. J. , Escavy J. Y. , Pravaz M.
Published: April 2006

Abstract The purpose of this study was lo evaluate the Young's modulus of cold and warm gutta‐percha. Rods of gutta‐percha, specially designed by three companies, were tested at 20°C and 55°C with a tensile testing machine. The Young's modulus, the yield strength and the percentage of deformation were automatically recorded. There was a statistically significant difference, for the three criteria, between the cold and warm gutta‐percha. Warm gutta‐percha presented a Young's modulus 100 times smaller, a yield strength 2 times smaller but a percentage of permanent deformation 10 times higher than cold gutta‐percha. Gutta‐percha Hygenic presented the best characteristics.
Anaerobic microorganisms in root canals of human teeth with chronic apical periodontitis detected by indirect immunofluorescence
Authors: Assed S. , Ito I.Y. , Leonardo M.R. , Silva L.A.B. , Lopatin D.E.
Published: April 2006

Abstract Aiming to assess the presence of selected anaerobic microorganisms in root canals of human teeth with chronic apical periodontitis, 25 central and lateral upper incisors presenting with radiographic evidence of chronic apical periodontitis were studied. I he pulp chamber was opened under aseptic conditions and samples of die root canal content were collected with sterile absorbent paper points, which were placed and dispersed in lest lubes containing reduced transport medium (RTF)Aliquots were dried on glass slides and stained by indirect immunofluorescence for detection of. Actinomyces viscosus, Fusobacterium nucleatum, Porphyromonas gingivalis and Prevotella intermedia. The results showed a positive indirect immunofluorescence reaction in 24 of the 25 samples. Fourteen were positive for die specie Actinomyces viscous, 12 for Prevotella intermedia, 10 for Fusobacterium nucleatum and 4 for Porphyromonas gingivalis. A semiquantitative assay was easily implemented for assessment of degree of infection by the organisms in individual cases.
Treatment of labial fenestration of maxillary central incisor
Authors: Yang Z.‐P
Published: April 2006

Abstract A case of external inflammatory root resorption and labial fenestration in a maxillary central incisor is presented. The root canal was dressed with pure calcium hydroxide mixed with normal saline for 1 month before it was obturated with gutta percha and apicoectomy surgery undertaken to attempt primary closure of the fenestration. The PDL and the fenestration healed uneventfully.
Oral soft tissue trauma: gingival degloving
Authors: Shockledge R. , Mackie I.
Published: April 2006

Abstract Ideally gingival degloving following a traumatic episode should be treated as soon as possible by repositioning the displaced gingivae and mucosa. The cases reported are of de‐gloving in die primary and permanent dentition. In both cases immediate assistance was sought from health professionals but no treatment was offered. The delay before attendance at the Dental Hospital meant that it was too late to offer active treatment. Instead supportive measures were1 instigated which resulted in eventual successful healing.
Impact resistance of crowned endodontically treated central incisors with internal composite cores
Authors: Cathro P. R. , Chandler N. P. , Hood J. A. A.
Published: April 2006

Abstract The impact fracture resistance of crowned endodontically treated teeth with composite cores but without posts, that had either no coronal dentin remaining or a 1mm dentin collar was compared to that of unrestored, caries free teeth. The teeth were struck mid‐labially to simulate a common trauma situation using a pendulum device and fracture1 resistance determined by calculation of absorbed energies. No significant difference was found between the intact teeth and the‐crowned root treated teeth with composite core and a 1mm dentin collar. Crowned loot treated teeth with a composite core but no coronal dentin had significantly reduced fracture resistance (p < 0.05). Teeth with the dentin collar mainly fractured obliquely from the bueeal crown margin to a point coincident with the simulated alveolus, representing a clinical situation which would allow retention rather than extraction of the tooth.
Assessment of antibacterial activity of endodontic sealers by a direct contact test
Authors: Weiss E. I. , Shalhav M. , Fuss Z.
Published: April 2006

Abstract It is recognized that endodontic success depends on bacterial elimination from the root and root canal system. Antibacterial activity of endodontic sealers can improve the success rate of endodontic treatment, provided the physical properties are not compromised. The aim of this study was to evaluate the antimicrobial properties of two endodontic sealers (AH26 and Endoflas) using a direct contact lest (DCT) which was designed for this purpose. The DCT is based on measuring the effect of close contact between lest bacteria and the tested material on the kinetics of bacterial outgrowth using a temperature controlled microplate spectrophotometer (THERMO max). For comparison, the agar diffusion test (AOT) was performed for both materials. The results of the DCT showed that Endoflas was a significantly more potent bacterial growth inhibitor than AH26, whereas when assessed with the ADT, AH26 was capable of producing a larger inhibition zone than Endoflas. The DCT, by being quantitative and virtually independent of solubility and diffusion, was found more‐ suitable to assay solid surfaces. The results demonstrated the added value of DCT in the study of the antimicrobial properties of endodontic sealers.
Pulp exposure after stepwise versus direct complete excavation of deep carious lesions in young posterior permanent teeth
Authors: Leksell E. , Ridell K. , Cvek M. , Mejàre I.
Published: April 2006

Abstract The aim was to assess the prevalence of pulp exposure alter stepwise versus direct complete excavation of permanent posterior teeth with deep carious lesions. The material, representing 116 patients aged 6‐l6yrs (= 10.2 yrs), consisted of 127 teeth with radiographs revealing carious lesions to such a depth that pulp exposure could he expected if direct complete excavation was performed. Teeth with clinical symptoms, other than transient pain shortly before treatment, were not accepted. The teeth were randomly selected for either treatment procedure. Stepwise excavation implied removal of the bulk of carious tissue and application of calcium hydroxide, followed by sealing of the cavity with zinc‐oxide eugenol cement. After a period of 8–24 weeks the rest of the carious dentin was removed and the cavity sealed with calcium hydroxide, zinc‐oxide‐eugenol (ZOE) and a restorative material. Direct complete excavation entailed removal of all carious dentin followed by sealing as mentioned above. In case of pulp exposure, pulp treatment was performed. The pulp was exposed in 40 of the teeth treated by direct complete excavation. The corresponding figure for those treated by stepwise excavation was 17.5%. The difference was statistically significant. The teeth with no pulp exposure after direct or stepwise excavation showed normal clinical and radiographic conditions at the last check‐up (= 43 mouths).
Conservative treatment of dens evaginatus of anterior teeth
Authors: Dankner E. , Harari D. , Rotstein I.
Published: April 2006

Abstract Dens evaginatus is a developmental malformation characterized by the presence of an extra cusp. In the anterior dentition, dens evaginatus is more commonly found in the maxilla and on the palatal surface of the tooth. Treatment may include root canal therapy followed by either an aesthetic restoration or a full crown coverage. In cases of mesiodens, supernumerary teeth or crowded dentition, extraction is often indicated. Presented is a case of a conservative treatment modality of dens evaginatus in a mandibular central incisor.
Is antibiotic prophylaxis required for endodontic treatment?
Authors: Lavelle C. L. B.
Published: April 2006

Abstract The stable prevalence of infective endocarditis since the advent of antibiotic prophylaxis for patients at‐risk reflects the increasing polymicrobial etiology of such infections not associated with dental procedures. In addition to concerns for the growing crisis for antibiotic‐resistant bacteria, the need for controlled clinical trials to determine the continued efficacy of prophylactic regimens for endodontic and other denial procedures cannot be overstated.
Accidental swallowing of endodontic instruments
Authors: Lambrianidis T. , Beltes P.
Published: April 2006

Abstract Swallowing or aspiration of a foreign body is a complication that may arise from any procedure in the oral cavity performed without the use of a rubber clam. Two cases of swallowed endodontic instilments and possible complications are presented. Emphasis is given in the discussion on the early diagnosis and treatment and primarly on prevention with the vise of rubber dam, an absolute essential during endodontic treatment.
Prognosis of permanent teeth with internal resorption: a clinical review
Authors: Çalişkan M. K. , Türkün M.
Published: April 2006

Abstract This study was performed in order to report the clinical features of internal resorption cases and evaluate their prognosis after endodontic treatment. Twenty‐seven patients with 28 teeth with internal resorption were referred to our clinic and 20 teeth were treated endodontically. Sixteen teeth had non‐perforating internal resorption and were treated by conventional root canal therapy. The remaining 4 teeth had perforating internal resorption and were initially treated by remineralization therapy with calcium hydroxide. The teeth treated by conventional root canal therapy showed clinical and radiographic evidence of healing. However, the remineralization therapy was successful in only one case. The three failed cases were subsequently treated by endodontic surgery. The surgical therapy was unsuccessful in one case due to extensive loss of marginal alveolar bone and increased tooth mobility.
A case of severe vestibular root angulation
Authors: Dotto A. L. , Capurro M. , Zmener O.
Published: April 2006

Abstract In this article, we describe the appearance and management of an impacted permanent tooth with severe vestibular root angulation. In addition, the possible origin of this type of root malformation as well as some of their epidemiologic aspects are discussed.
An evaluation of after‐office‐hour dental trauma in Singapore
Authors: Sae‐Lim V. , Yuen K. W.
Published: April 2006

Abstract The purpose of this study was to assess the post‐traumatic sequelae and treatment outcome and the corresponding prognostic factors at the initial emergency visit. Over a 5‐year period, the authors collected case records from 129 dental trauma patients. These patients had been referred subsequent to receiving emergency treatment after office hours at the Accident and Emergency Department of Singapore General Hospital. After the exclusion of 31 cases with concomitant fracture of maxilla and/or mandible and cases with insufficient documentation, the final study sample consisted of 98 patients (41 males, 57 females) who had sustained injuries to 264 permanent teeth. The main cause of dental trauma was falls (56%), and the main type of injuries was periodontal tissue injuries with or without concomitant injuries to hard tissue, including root fracture (73%). For the final evaluation, teeth with insufficient recall period were excluded before univariate and multivariate stepwise logistic regression analysis. It was found that for 100 teeth with luxation type of injuries, the presence of concomitant hard tissue injuries retained prognostic significance for pulpal outcome (p<0.001) after adjusting for severity of luxation, while the severity of luxation was the only significant factor for periodontal outcome (p<0.001). For 34 avulsed teeth, the stage of root development was the major factor associated with the pulpal outcome (p = 0.003), while extra‐alveolar storage media were found to be significantly related to the periodontal outcome (p<0.001). For 72 teeth with hard tissue injuries, first‐visit interval played a significant role in the outcome (p = 0.03). Although the sample size in the root fracture group was too small for such statistical analysis, the results indicated that patient education on dental trauma was an important factor. Thorough standardized documentation was also recommended to facilitate optimal follow‐up management and future research as well as medico‐legal purposes.
Radiological assessment of the effects of potential root‐end filling materials on healing after endodontic surgery
Authors: Chong B.S. , Ford T.R. Pitt , Wilson R.F.
Published: April 2006

Abstract The effects of three root‐end filling materials on healing following endodontic surgery were assessed radiologically and correlated with histological findings reported elsewhere. The materials compared were a light‐cured glass ionomer cement (Vitrebond), a reinforced zinc oxide‐eugenol cement (Kalzinol) and amalgam. The root canals of 27 two‐rooted mandibular premolar teeth of six beagle dogs were inoculated with endodontic pathogenic bacteria to induce periradicular lesions. The roots were apicected and root‐end cavities filled with the tested filling materials. The teeth and surrounding jaw were removed after 4 weeks (30 roots) or 8 weeks (24 roots). Radiographs were taken of each jaw section and subjected to image analysis. Healing was evaluated based on measurements of the size of the periradicular radiolucent areas. ANOVA disclosed no statistically significant differences in the size of the periradicular areas either between time periods or between materials. These results did not correlate with the tissue responses in the same material as assessed histologically and previously reported. The use of radiographs alone to assess healing after endodontic surgery in the dog mandible is unsatisfactory, and should not be regarded as a substitute for histological examination for the determination of healing.
Cutting pattern of Flexogate instruments in plastic blocks
Authors: Bedford‐Roberts E. , Curtis R. V. , Ford T. R. Pitt
Published: April 2006

Abstract Design modifications of endodontic instruments have been made to improve instrumentation in curved root canals. A new instrument, the Flexogate (Maillefer), has been introduced to overcome some of the problems associated with preparation of the apical pan of the root canal. The purpose of this study was to investigate the cutting pattern of Flexogates in curved canals (45°) in clear plastic blocks, prepared by lour different operators. Image analysis was used to take accurate measurements of canal shape before and after instrumentation to calculate cutting patterns. The results showed that Flexogates did not remain centred in the canal of a plastic block during cutting; maximum transportation occurred in the apical third of the outer curve, with little or none in the middle and coronal thirds. The clinical implications of this study require further investigation of the effect of coronal preflaring, and experimentation in teeth.
Effect of XeCl‐308nm excimer laser on the mineral content of human dentin
Authors: Dankner E. , Neev J. , Stabholz A. , Rotstein I.
Published: April 2006

Abstract The effect of the XeCl‐308nm excimer laser on the mineral content and surface morphology of cut dentin was examined in ten extracted human teeth. Each dentin specimen was lased for 4 s at a fluence of 1 J/cm2 and frequency of 25 Hz. Non‐lased area of the same specimen served as control. Scanning electron microscopy and energy dispersive spectrometry revealed a significant decreases in the phosphorus levels following laser treatment. A decrease in calcium levels also occurred but was not statistically significant. Nonsignificant changes in sulphur and potassium levels were also noted. Morphologically, the lased dentin showed an apparently melted surface with partial obstruction of the dentin tubules as well as cracks along the lased surface. Therefore, it appeared that laser treatment may alter the chemical structure as well as the surface morphology of the dentin.
Toothache with a multifactorial etiology: a case report
Authors: Chen Y. H. M. , Tseng C. C. , Chao W. Y. , Harn W. M. , Chung S. F.
Published: April 2006

Abstract A case report of orofacial pain originating from both dental and nondental conditions is presented. The spontaneous throbbing pain initiated from the left maxillary second premolar and spread throughout the entire upper part of the lace to the frontoparietal area. Root canal treatment of the maxillary second premolar did not resolve the chief complaint. Magnetic resonance imaging examination revealed hypertrophy of the left inferior turbinate and soft tissue haziness in the left maxillary sinus floor. After antrostomy, submucosal turbinectomy; and endodontic treatment, the patient was free from pain. The final diagnosis of this case, in addition to pulpitis, was maxillary sinusitis with chronic rhinitis. The multiple factors associated with the etiology made the diagnosis difficult. The mechanism of referred pain from the maxillary sinus and paranasal nuicosa to the maxillary teeth and face is discussed.
Mixture of goods
Authors: McCormack Gerard
Published: April 2006

Problems relating to the admixture of goods have arisen in many contexts. An up-to-date example is where the supplier of goods subject to a reservation of title clause lays claim to materials in which the goods supplied have been incorporated. Notwithstanding the practical importance of the subject, the matter has not perhaps attracted the degree of discussion that it deserves. This article attempts to redress the balance somewhat but firstly an effort is made to put terminological inexactitude and imprecision at rest.
Pirelli re-examined
Authors: McKendrick Ewan
Published: April 2006

One of the interesting facets of the decision of the House of Lords in Murphy v Brentwood District Council is the fresh interpretation which it has placed upon some of the earlier leading authorities. One case which has been subjected to this process of re-interpretation is the decision of the House of Lords in Pirelli General Cable Works Ltd v Oscar Faber & Partners. It was rationalised by Lord Keith as a case which fell ‘within the principle of Hedley Byrne & Co Ltd v Heller & Partners Ltd’. The aim of this short note is to subject this re-interpretation to examination and to suggest that, ironically, its consequence may be the adoption of the very proposition of law rejected by their Lordships in Pirelli, namely that the cause of action accrued on the date on which the damage was discovered or should, with the exercise of reasonable diligence, have been discovered.
Revisiting pure economic loss: lessons to be learnt from the Supreme Court of Canada?
Authors: Giliker Paula
Published: April 2006

This article examines the treatment of pure economic loss claims in England and Canada. The two jurisdictions have much in common. Starting from the same case sources, the common law of each system has struggled to deal with claims for negligently-incurred pure economic loss. Yet, the systems diverged in the 1990s when the Canadian Supreme Court refused to follow the lead of Murphy v Brentwood DC and reiterated its adherence to the Anns two-stage test. It is submitted that, in view of recent developments which suggest the gradual convergence of the two systems, English law should carefully examine the categorisation approach adopted by the Canadian courts. The current English position is far from clear, and the Canadian model is capable of bringing transparency and greater clarity to this difficult area of law.
Insurance and the tort system
Authors: Lewis Richard
Published: April 2006

This article examines Stapleton's view that insurance has lacked influence and been no more than a ‘makeweight’ argument in the development of tort liability. Looking at the wider context, the article describes the overwhelming importance of insurers to the litigation system and argues that all cases are affected by insurance practice. It distinguishes the effect of insurance upon judicial fact finding, on the one hand, and the development of common law rules, on the other. It examines the ability of insurers to influence legislation relevant to the tort system. It concludes that, if account is taken of all these areas, insurance has been of vital importance to the law of tort. Without it, the system of personal injury compensation would not have survived. This conclusion is reached even though insurance is largely ignored by the great majority of tort texts.
Graded recruitment and inactivation of single InsP3 receptor Ca2+‐release channels: implications for quartal Ca2+release
Authors: Ionescu Lucian , Cheung King‐Ho , Vais Horia , Mak Don‐On Daniel , White Carl , Foskett J. Kevin
Published: April 2006

Modulation of cytoplasmic free Ca2+ concentration ([Ca2+]i) by receptor‐mediated generation of inositol 1,4,5‐trisphosphate (InsP3) and activation of its receptor (InsP3R), a Ca2+‐release channel in the endoplasmic reticulum, is a ubiquitous signalling mechanism. A fundamental aspect of InsP3‐mediated signalling is the graded release of Ca2+ in response to incremental levels of stimuli. Ca2+ release has a transient fast phase, whose rate is proportional to [InsP3], followed by a much slower one even in constant [InsP3]. Many schemes have been proposed to account for quantal Ca2+ release, including the presence of heterogeneous channels and Ca2+ stores with various mechanisms of release termination. Here, we demonstrate that mechanisms intrinsic to the single InsP3R channel can account for quantal Ca2+ release. Patch‐clamp electrophysiology of isolated insect Sf9 cell nuclei revealed a consistent and high probability of detecting functional endogenous InsP3R channels, enabling InsP3‐induced channel inactivation to be identified as an inevitable consequence of activation, and allowing the average number of activated channels in the membrane patch (NA) to be accurately quantified. InsP3‐activated channels invariably inactivated, with average duration of channel activity reduced by high [Ca2+]i and suboptimal [InsP3]. Unexpectedly, NA was found to be a graded function of both [Ca2+]i and [InsP3]. A qualitative model involving Ca2+‐induced InsP3R sequestration and inactivation can account for these observations. These results suggest that apparent heterogeneous ligand sensitivity can be generated in a homogeneous population of InsP3R channels, providing a mechanism for graded Ca2+ release that is intrinsic to the InsP3R Ca2+ release channel itself.
Myosin heavy chain isoform composition and stretch activation kinetics in single fibres of Xenopus laevis iliofibularis muscle
Authors: Andruchova Olena , Stephenson Gabriela M. M. , Andruchov Oleg , Stephenson D. George , Galler Stefan
Published: April 2006

Skeletal muscle is composed of specialized fibre types that enable it to fulfil complex and variable functional needs. Muscle fibres of Xenopus laevis, a frog formerly classified as a toad, were the first to be typed based on a combination of physiological, morphological, histochemical and biochemical characteristics. Currently the most widely accepted criterion for muscle fibre typing is the myosin heavy chain (MHC) isoform composition because it is assumed that variations of this protein are the most important contributors to functional diversity. Yet this criterion has not been used for classification of Xenopus fibres due to the lack of an effective protocol for MHC isoform analysis. In the present study we aimed to resolve and visualize electrophoretically the MHC isoforms expressed in the iliofibularis muscle of Xenopus laevis, to define their functional identity and to classify the fibres based on their MHC isoform composition. Using a SDS‐PAGE protocol that proved successful with mammalian muscle MHC isoforms, we were able to detect five MHC isoforms in Xenopus iliofibularis muscle. The kinetics of stretch‐induced force transients (stretch activation) produced by a fibre was strongly correlated with its MHC isoform content indicating that the five MHC isoforms confer different kinetics characteristics. Hybrid fibre types containing two MHC isoforms exhibited stretch activation kinetics parameters that were intermediate between those of the corresponding pure fibre types. These results clearly show that the MHC isoforms expressed in Xenopus muscle are functionally different thereby validating the idea that MHC isoform composition is the most reliable criterion for vertebrate skeletal muscle fibre type classification. Thus, our results lay the foundation for the unequivocal classification of the muscle fibres in the Xenopus iliofibularis muscle and for gaining further insights into skeletal muscle fibre diversity.
CaV3.2 is the major molecular substrate for redox regulation of T‐type Ca2+ channels in the rat and mouse thalamus
Authors: Joksovic Pavle M. , Nelson Michael T. , Jevtovic‐Todorovic Vesna , Patel Manoj K. , Perez‐Reyes Edward , Campbell Kevin P. , Chen Chien‐Chang , Todorovic Slobodan M.
Published: April 2006

Although T‐type Ca2+ channels in the thalamus play a crucial role in determining neuronal excitability and are involved in sensory processing and pathophysiology of epilepsy, little is known about the molecular mechanisms involved in their regulation. Here, we report that reducing agents, including endogenous sulfur‐containing amino acid l‐cysteine, selectively enhance native T‐type currents in reticular thalamic (nRT) neurons and recombinant CaV3.2 (α1H) currents, but not native and recombinant CaV3.1 (α1G)‐ and CaV3.3 (α1I)‐based currents. Consistent with this data, T‐type currents of nRT neurons from transgenic mice lacking CaV3.2 channel expression were not modulated by reducing agents. In contrast, oxidizing agents inhibited all native and recombinant T‐type currents non‐selectively. Thus, our findings directly demonstrate that CaV3.2 channels are the main molecular substrate for redox regulation of neuronal T‐type channels. In addition, because thalamic T‐type channels generate low‐threshold Ca2+ spikes that directly correlate with burst firing in these neurons, differential redox regulation of these channels may have an important function in controlling cellular excitability in physiological and pathological conditions and fine‐tuning of the flow of sensory information into the central nervous system.
CRACM1 Is a Plasma Membrane Protein Essential for Store-Operated Ca
2+
Entry
Authors: Vig M. , Peinelt C. , Beck A. , Koomoa D. L. , Rabah D. , Koblan-Huberson M. , Kraft S. , Turner H. , Fleig A. , Penner R. , Kinet J.-P.
Published: April 2006

Store-operated Ca
2+
entry is mediated by Ca
2+
release–activated Ca
2+
(CRAC) channels following Ca
2+
release from intracellular stores. We performed a genome-wide RNA interference (RNAi) screen in
Drosophila
cells to identify proteins that inhibit store-operated Ca
2+
influx. A secondary patch-clamp screen identified CRACM1 and CRACM2 (CRAC modulators 1 and 2) as modulators of
Drosophila
CRAC currents. We characterized the human ortholog of CRACM1, a plasma membrane–resident protein encoded by gene
FLJ14466
. Although overexpression of CRACM1 did not affect CRAC currents, RNAi-mediated knockdown disrupted its activation. CRACM1 could be the CRAC channel itself, a subunit of it, or a component of the CRAC signaling machinery.
Three cases of pancreatic serous cystadenoma and endocrine tumour
Authors: Blandamura Stella , Parenti Anna , Famengo Barbara , Canesso Alessandra , Moschino Paolo , Pasquali Claudio , Pizzi Sara , Guzzardo Vincenza , Ninfo Vito
Published: April 2006

Aims:To report three cases of serous cystadenoma and endocrine tumour in the same pancreas, to review the literature and to evaluate the clinicopathological features of the tumours.

Cases:Three women (71, 57 and 31 years old) were admitted to hospital, two for diseases unrelated to the pancreas and the third for increasing obstructive jaundice in von Hippel-Lindau disease. Preoperative examination showed two distinct lesions in the first patient and only cystic lesions in the other two.

Results:Histological examination of the pancreas showed one serous oligocystic adenoma associated with a benign, well-differentiated endocrine tumour, one serous oligocystic adenoma associated with an endocrine microadenoma, and a von Hippel-Lindau-related cystic neoplasm with a well-differentiated endocrine carcinoma.

Conclusions:Serous cystadenoma associated with endocrine tumour shows some clinicopathological differences with respect to the two tumours considered separately, and with respect to von Hippel-Lindau-related cases, although there is no convincing evidence at present to justify considering this association as a separate entity.
Are patients morally responsible for their errors?
Authors: Buetow S , Elwyn G
Published: April 2006

Amid neglect of patients’ contribution to error has been a failure to ask whether patients are morally responsible for their errors. This paper aims to help answer this question and so define a worthy response to the errors. Recent work on medical errors has emphasised system deficiencies and discouraged finding people to blame. We scrutinise this approach from an incompatibilist, agent causation position and draw on Hart’s taxonomy of four senses of moral responsibility: role responsibility; capacity responsibility; causal responsibility; and liability responsibility. Each sense is shown to contribute to an overall theoretical judgment as to whether patients are morally responsible for their errors (and success in avoiding them). Though how to weight the senses is unclear, patients appear to be morally responsible for the avoidable errors they make, contribute to or can influence.
SU(2) AND SU(3) YANG–MILLS THERMODYNAMICS AND SOME IMPLICATIONS
Authors: HOFMANN RALF
Published: April 2006

We sketch the development of effective theories for SU(2) and SU(3) Yang–Mills thermodynamics. The most important results are quoted and some implications for particle physics and cosmology are discussed.
EXPERIMENT AND THEORY IN COMPUTATIONS OF THE He ATOM GROUND STATE
Authors: SCHWARTZ CHARLES
Published: April 2006

Extensive variational computations are reported for the ground state energy of the non-relativistic two-electron atom. Several different sets of basis functions were systematically explored, starting with the original scheme of Hylleraas. The most rapid convergence is found with a combination of negative powers and a logarithm of the coordinate s = r1 + r2. At N = 3091 terms we pass the previous best calculation (Korobov's 25 decimal accuracy with N = 5200 terms) and we stop at N = 10257 with E = -2.90372, 43770, 34119, 59831, 11592, 45194, 40444, ….

Previous mathematical analysis sought to link the convergence rate of such calculations to specific analytic properties of the functions involved. The application of that theory to this new experimental data leaves a rather frustrating situation, where we seem able to do little more than invoke vague concepts, such as "flexibility." We conclude that theoretical understanding here lags well behind the power of available computing machinery.
ONTOLOGICAL APPROACH OF ORGANIZATIONAL KNOWLEDGE TO SUPPORT COLLABORATIVE PRODUCT DEVELOPMENT
Authors: CHEUNG WAI M.
Published: April 2006

This paper discusses the theoretical aspects and applications of a novel methodology for exploiting a knowledge management editor tool to structure organizational knowledge and integrate it with product development activities. An organizational knowledge framework for capturing and representing manufacturing know-how has been developed using an ontological approach. The captured knowledge is converted into the industry-standard eXtensible Mark-up Language (XML) and then shared within a web-centric Product Data Management (PDM) enterprise system to support a collaborative and distributed product development environment. The benefit of adopting such an approach is the closer integration between the activities taking place during early design stage. In particular, the effectiveness of decision making is increased.
Deglutitive upper esophageal sphincter relaxation: a study of 75 volunteer subjects using solid-state high-resolution manometry
Authors: Ghosh Sudip K. , Pandolfino John E. , Zhang Qing , Jarosz Andrew , Kahrilas Peter J.
Published: April 2006

This study aimed to use a novel high-resolution manometry (HRM) system to establish normative values for deglutitive upper esophageal sphincter (UES) relaxation. Seventy-five asymptomatic controls were studied. A solid-state HRM assembly with 36 circumferential sensors spaced 1 cm apart was positioned to record from the hypopharynx to the stomach. Subjects performed ten 5-ml water swallows and one each of 1-, 10-, and 20-ml volume swallows. Pressure profiles across the UES were analyzed using customized computational algorithms that measured 1) the relaxation interval (RI), 2) the median intrabolus pressure (mIBP) during the RI, and 3) the deglutitive sphincter resistance (DSR) defined as mIBP/RI. The automated analysis succeeded in confirming bolus volume modulation of both the RI and the mIBP with the mean RI ranging from 0.32 to 0.50 s and mIBP ranging from 5.93 to 13.80 mmHg for 1- and 20-ml swallows, respectively. DSR was relatively independent of bolus volume. Peak pharyngeal contraction during the return to the resting state postswallow was almost 300 mmHg, again independent of bolus volume. We performed a detailed analysis of deglutitive UES relaxation with a novel HRM system and customized software. The enhanced spatial resolution of HRM allows for the accurate, automated assessment of UES relaxation and intrabolus pressure characteristics, in both cases confirming the volume-dependent effects and absolute values of these parameters previously demonstrated by detailed analysis of concurrent manometry/fluoroscopy data. Normative values were established to aid in future clinical and investigative studies.
IL-1β signaling in cat lower esophageal sphincter circular muscle
Authors: Cao Weibiao , Cheng Ling , Behar Jose , Biancani Piero , Harnett Karen M.
Published: April 2006

In a cat model of acute experimental esophagitis, resting in vivo lower esophageal sphincter (LES) pressure and in vitro tone are lower than in normal LES, and the LES circular smooth muscle layer contains elevated levels of IL-1β that decrease the LES tone of normal cats. We now examined the mechanisms of IL-1β-induced reduction in LES tone. IL-1β significantly reduced acetylcholine-induced Ca2+release in Ca2+-free medium, and this effect was partially reversed by catalase, demonstrating a role of H2O2in these changes. IL-1β significantly increased the production of H2O2, and the increase was blocked by the p38 MAPK inhibitor SB-203580, by the cytosolic phospholipase A2(cPLA2) inhibitor AACOCF3, and by the NADPH oxidase inhibitor apocynin, but not by the MEK1 inhibitor PD-98059. IL-1β significantly increased the phosphorylation of p38 MAPK and cPLA2. IL-1β-induced cPLA2phosphorylation was blocked by SB-203580 but not by AACOCF3, suggesting sequential activation of p38 MAPK-phosphorylating cPLA2. The IL-1β-induced reduction in LES tone was partially reversed by AACOCF3 and by the Ca2+-insensitive PLA2inhibitor bromoenol lactone (BEL). IL-1β significantly increased cyclooxygenase (COX)-2 and PGE2levels. The increase in PGE2was blocked by SB-203580, AACOCF3, BEL, and the COX-2 inhibitor NS-398 but not by PD-98059 or the COX-1 inhibitor valeryl salicylate. The data suggested that IL-1β reduces LES tone by producing H2O2, which may affect Ca2+-release mechanisms and increase the synthesis of COX-2 and PGE2. Both H2O2and PGE2production depend on sequential activation of p38 MAPK and cPLA2. cPLA2activates NADPH oxidases, producing H2O2, and may produce arachidonic acid, converted to PGE2via COX-2.
Evidence of impaired hypoxic vasodilation after intermediate-duration hypoxic exposure in humans
Authors: Gilmartin Geoffrey , Tamisier Renaud , Anand Amit , Cunnington David , Weiss J. Woodrow
Published: April 2006

Systemic hemodynamics, including forearm blood flow and ventilatory parameters, were evaluated in 21 subjects before and after exposure to 8 h of poikilocapnic hypoxia. To evaluate the role of sympathetic nervous system activation in the changes, in 10 of these subjects, we measured muscle sympathetic nerve activity (MSNA) before and after exposure, and the remaining 11 subjects received intra-arterial phentolamine infusion in the brachial artery to define vascular tone in the absence of sympathetically mediated vasoconstriction. Short-term ventilatory acclimatization occurred as evidenced by a decrease in resting Pco2 (from 42 ± 1.4 to 37 ± 0.96 mmHg) and by an increase in the slope of the ventilatory response to acute hypoxia [from 0.7 ± 0.1 to 1.2 ± 0.2 l·min−1·%SpO2 (blood O2 saturation from pulse oximetry)] after exposure. Subjects demonstrated a significant increase in resting heart rate (from 61 ± 2 to 65 ± 2 beats/min) and diastolic blood pressure (from 64.8 ± 2.7 to 70.4 ± 2.0 mmHg). MSNA did not change significantly after exposure, although there was a trend toward a decrease in burst frequency (from 19.8 ± 4.1 to 14.3 ± 1.2 bursts/min). Forearm vascular resistance showed a significant decrease after termination of exposure (from 37.7 ± 3.6 to 27.6 ± 2.7 mmHg·ml−1·min·100 g tissue, P < 0.05). Initially, progressive isocapnic hypoxia elicited significant vasodilation, but after 8 h of poikilocapnic hypoxic exposure, the acute challenge failed to change forearm vascular resistance. Local α-blockade with phentolamine restored the vasodilatory response to acute hypoxia in the postexposure setting.
Point:Counterpoint: Cardiovascular variability is/is not an index of autonomic control of circulation
Authors: Parati Gianfranco , Mancia Giuseppe , Rienzo Marco Di , Castiglioni Paolo
Published: April 2006

PURPOSE AND SCOPE OF THE POINT:COUNTERPOINT DEBATES

This series of debates was initiated for the Journal of Applied Physiology because we believe an important means of searching for truth is through debate where contradictory viewpoints are put forward. This dialectic process whereby a thesis is advanced, then opposed by an antithesis, with a synthesis subsequently arrived at, is a powerful and often entertaining method for gaining knowledge and for understanding the source of a controversy. Before reading these Point:Counterpoint manuscripts or preparing a brief commentary on their content (see below for instructions), the reader should understand that authors on each side of the debate are expected to advance a polarized viewpoint and to select the most convincing data to support their position. This approach differs markedly from the review article where the reader expects the author to present balanced coverage of the topic. Each of the authors has been strictly limited in the lengths of both the manuscript (1,200 words) and the rebuttal (400). The number of references to publications is also limited to 30, and citation of unpublished findings is prohibited.