bluuebunny/crossref_metadata_2025_split huggingface dataset:
The use of a modelling technique to investigate the root canal morphology of mandibular incisors
Authors: GOMES B. P. F. A. , RODRIGUES H. H. , TANCREDO N. 
Published: September 2007

SummaryThe prime objective of this study was to develop and test a method of modelling the dental root canal system using a vinyl resin, type UCAR‐VYHD. It also aimed to verify if the resin models allow a three‐dimensional evaluation of those features of the pulpal morphology of human permanent mandibular incisor teeth, which might be associated with periodontal disease. One hundred and eleven freshly extracted teeth were studied. Pre‐extraction clinical records and periapical radiographs were used to deduce the presence or absence of periodontal disease. Each extracted tooth was radiographed in two perpendicular planes before being opened by conventional orthograde endodontic technique, and photographed in a scanning electron microscope. The patent pulp space was then obturated with the vinyl resin. Scanning electron photomicrographs of the resin replicas and of the teeth were compared with the earlier radiographic images to correlate the morphological findings. The numbers of root canals and apical foramina were recorded. This study showed that in mandibular incisors with periodontal disease there was a relatively low incidence of lateral canals (7.2%). The modelling technique was found to be reliable, reproducible, and provided sufficient detail to allow three‐dimensional analysis of root canal morphology.
Time‐course and risk analyses of the development and healing of chronic apical periodontitis in man
Authors: ØRSTAVIK D. 
Published: September 2007

SummaryRoots with and without preoperative chronic apical periodontitis were root canal treated and followed clinically and radiographically yearly for up to 4 years. Of 732 roots treated, 599 (82%) were available for evaluation at one or several recalls. Chronic apical periodontitis (CAP) was recorded with the periapical index scoring system. CAP developed in 29 of 473 (6%) of teeth without preoperative signs of disease, whereas 111 of 126 (88%) initially diseased roots showed signs of healing. The rate of healing CAP and the rate of emerging CAP were calculated, and analyses of event occurrence each year of observation were performed. Peak incidence of healing or emerging CAP was at 1 year in both instances. Risk assessments at 2, 3, and 4 years did not indicate an added risk of filled roots developing CAP during this period. Complete healing of preoperative CAP in some instances required 4 years for completion, while signs of initiated, but incomplete, healing were visible in at least 89% of all healing roots after 1 year. Risk analyses may provide relevant information in addition to or in substitution for success/failure analyses.
A comparison of bending and torsional properties of K‐files manufactured with different metallic alloys
Authors: CANALDA‐SAHLI C , BRAU‐AGUADE E. , BERASTEGUI‐JIMENO E. 
Published: September 2007

SummaryThe purpose of this study was to compare bending (bending moment) and resistance to fracture by twisting (torsional moment and angular deflection) of triangular cross‐section K‐files made of either nickel titanium (Nitiflex, Naviflex), titanium (Microtitane) or stainless steel (Flexofile, Flex‐R). A total of 200 files were tested, 10 instruments for each type from size 25 to 40, according to ANSI/ADA specification no. 28 and ISO reference no. 3630. Files made of nickel titanium, especially Nitiflex, were the most flexible. Stainless steel instruments presented a higher bending moment than files made of nickel titanium and titanium, particularly Flex‐R sizes 35 and 40. With regard to resistance to fracture, measured by angular deflection at the failure point, Flexofile followed by Flex‐R were the most resistant to fracture and Nitiflex were the least resistant. Differences in angular deflection among file groups were greater than those for torsional moment. Thus, it seems that angular deflection is a more specific measurement for assessing resistance to fracture by twisting.
Pattern of transmission of laser light in teeth
Authors: ODOR T. M. , WATSON T. F. , FORD T. R. PITT , McDONALD F. 
Published: September 2007

SummaryThis study examined the transmission of helium neon laser light in 20 dog and human teeth. The effect of probe position and angulation was observed both macroscopically and at a microscopic level using con‐focal microscopy. In all teeth in both species, laser light was transmitted through teeth to the pulpal surface with the light following the path of the enamel prisms and dentinal tubules. Probe angulation did not affect the pattern of light transmission, nor did probe position; however, the position of the probe on the tooth surface determined which section of the pulp was illuminated. Enamel and dentine together are able to collect and distribute light within the tooth, with both enamel prisms and dentinal tubules acting as optical fibres.
The effect of smear layer on microbial coronal leakage of gutta‐percha root fillings
Authors: CHAILERTVANITKUL P. , SAUNDERS W. P. , MACKENZIE D. 
Published: September 2007

SummaryThe aim of this in vitro study was to determine the effect of removal of the smear layer on canal obturation as measured by penetration of bacteria from a coronal direction. One hundred and twenty extracted human teeth with straight, single root canals were decoronated. The canals were prepared using the modified double‐flared technique with balanced force under copious irrigation. The apical matrix was prepared to size 40 and apical patency subsequently confirmed with a size 15 file. The teeth were divided randomly into experimental groups (80 teeth) and control groups (40 teeth). The root canals of 40 experimental and 20 control teeth were rinsed with 40% citric acid and 2% NaOCl to remove the smear layer before obturation. In experimental groups, 20 teeth with smear layer intact and 20 teeth with smear layer removed were obturated with lateral condensation of cold gutta‐percha and Apexit sealer. A further 20 teeth with smear layer intact and 20 teeth with smear layer removed were obturated with the Trifecta technique with the same sealer. In control groups, 10 teeth with smear layer intact and 10 teeth with smear layer removed were obturated with lateral condensation of cold gutta‐percha and Apexit sealer. These teeth were completely sealed both coronally and apically to serve as negative controls. The remaining 20 teeth with either smear layer intact or smear layer removed were not obturated and served as the positive controls. The root surface of each tooth was sealed with nail varnish. The cut end of a polypropylene tube was sealed around the coronal part of each root canal so that bacteria placed therein could move only through the obturated canal space. Each root was placed in a glass bottle containing sterile Todd‐Hewitt Broth (THB) and aliquots of 0.5 ml of THB were injected into the polypropylene tube. The model system was centrifuged at 168 g. An innoculum of Streptococcus sanguis in THB was placed in each coronal chamber at 5‐day intervals and daily observations were made for bacterial growth in the apical reservoir for 90 days. All positive control teeth showed bacterial penetration within 24 h, while the negative control teeth remained uncon‐taminated throughout the test period. Leakage through the experimental teeth was variable ranging from 7 to 86 days. There was no statistical significant difference (P > 0.05) in leakage between the obturated canal when the smear layer was either removed or intact.
The application of the buccal object rule for the determination of calcified root canals
Authors: KHABBAZ M. G. , SEREFOGLOU M. H. 
Published: September 2007

SummaryRoot canal calcification represents a serious problem which often occurs in clinical practice. Calcified root canals are difficult or even impossible to find and treat conservatively. In this paper, a technique is proposed which may be helpful in detecting and locating calcified root canal(s) and properly treating them. The proposed technique is simple and easy to perform in posterior and anterior teeth, and it may be useful in everyday clinical practice.
The maxillary second molar: variations in the number of roots and canals
Authors: PEIKOFF M. D. , CHRISTIE W. H. , FOGEL H. M. 
Published: September 2007

SummaryA retrospective study was undertaken of 520 completed endodontic treatments of maxillary second molar teeth which were selected from a specialty endodontic practice. Radiographs were reviewed and studied, a classification of antomical root and canal variations was devised, and the frequency with which each variant occurred was recorded. There were six variants which occurred frequently enough to be considered as separate anatomic categories and their frequency of occurrence is illustrated. The six variants found in the study and their frequency of occurrence are as follows: (1) three separate roots and three separate canals (56.9%); (2) three separate roots and four canals (two in the mesiobuccal root) (22.7%); (3) three roots and canals whose mesiobuccal and distobuccal canals combine to form a common buccal with a separate palatal (9%); (4) two separate roots with a single canal in each (6.9%); (5) one main root and canal (3.1%); and (6) four separate roots and four separate canals including two palatal (1.4%). Clinical examples of these deviant variations are also presented.
A putative house‐cleaning enzyme encoded within an integron array: 1.8 Å crystal structure defines a new MazG subtype
Authors: Robinson Andrew , Guilfoyle Amy P. , Harrop Stephen J. , Boucher Yan , Stokes H. W. , Curmi Paul M. G. , Mabbutt Bridget C. 
Published: September 2007

SummaryMobile gene cassettes collectively contain a highly diverse pool of novel genes that encode many novel adaptive functions. In the non‐clinical context, the function of almost all of the encoded proteins remains unknown despite the enormous size of this mobile gene pool. We have been characterizing cassette arrays by taking advantage of the fact that they cluster at discrete sites in chromosomes; even large arrays are thus recoverable in a relatively small number of clones in genomic libraries. In one assembled array of 116 cassettes from the marine bacterium Vibrio sp. DAT722, a putative MazG protein is encoded within the 21st cassette. Because MazG proteins are implicated in a number of cellular processes, including house‐cleaning and stress survival, the presence of such a protein in a mobile cassette was noteworthy. Here we solve the crystal structure of this α‐helical protein, and define both open and closed states of a new variant of the MazG family. Functional assays confirm that the protein is a dNTP pyrophosphohydrolase, with marked preferences for dCTP and dATP. We hypothesize that iMazG acts as a house‐cleaning enzyme, preventing the incorporation of damaging non‐canonical nucleotides into host‐cell DNA.
Cosmological constraints from the 100-deg2 weak-lensing survey
Authors: Benjamin Jonathan , Heymans Catherine , Semboloni Elisabetta , Van Waerbeke Ludovic , Hoekstra Henk , Erben Thomas , Gladders Michael D. , Hetterscheidt Marco , Mellier Yannick , Yee H. K. C. 
Published: September 2007

Abstract
We present a cosmic shear analysis of the 100-deg2 weak-lensing survey, combining data from the CFHTLS-Wide, RCS, VIRMOS-DESCART and GaBoDS surveys. Spanning ∼100 deg2, with a median source redshift z∼ 0.78, this combined survey allows us to place tight joint constraints on the matter density parameter Ωm, and the amplitude of the matter power spectrum σ8, finding σ8(Ωm/0.24)0.59= 0.84 ± 0.05. Tables of the measured shear correlation function and the calculated covariance matrix for each survey are included as supplementary material to the online version of this article.
The accuracy of our results is a marked improvement on previous work owing to three important differences in our analysis; we correctly account for sample variance errors by including a non-Gaussian contribution estimated from numerical simulations; we correct the measured shear for a calibration bias as estimated from simulated data; we model the redshift distribution, n(z), of each survey from the largest deep photometric redshift catalogue currently available from the CFHTLS-Deep. This catalogue is randomly sampled to reproduce the magnitude distribution of each survey with the resulting survey-dependent n(z) parametrized using two different models. While our results are consistent for the n(z) models tested, we find that our cosmological parameter constraints depend weakly (at the 5 per cent level) on the inclusion or exclusion of galaxies with low-confidence photometric redshift estimates (z &gt; 1.5). These high-redshift galaxies are relatively few in number but contribute a significant weak-lensing signal. It will therefore be important for future weak-lensing surveys to obtain near-infrared data to reliably determine the number of high-redshift galaxies in cosmic shear analyses.
Acute exposure to streptozotocin but not human proinflammatory cytokines impairs neonatal porcine islet insulin secretion in vitro but not in vivo
Authors: Harb George , Toreson Jeff , Dufour Janette , Korbutt Gregory 
Published: September 2007

Abstract:  Background:  Neonatal porcine islets (NPI) are a potentially useful source of beta cells for transplantation to treat type 1 diabetes mellitus. However, cytokine exposure following xenotransplantation is likely to prevent successful NPI xenograft survival. In this study, we examined the effects of human proinflammatory cytokines (IL‐1β, IFNγ, TNFα) on NPI function and cell death. These cytokines have been shown to be cytotoxic to beta cells, in part through the generation of nitric oxide. Therefore, we also examined NPI function after acute oxidative stress caused by streptozotocin (STZ), a nitric oxide‐generating beta cell cytotoxin.Methods:  Cultured NPI were exposed to human IL‐1β, TNFα and IFNγ for 48 h or STZ for 30 min in vitro. Cytokine exposed islets were transplanted into diabetic mice and assessed for function. Mice transplanted with control NPI were injected with STZ and also assessed metabolically.Results:  In vitro exposure to STZ, but not cytokines, significantly reduced NPI glucose stimulated insulin secretion (1.1 ± 0.1 vs. 4.3 ± 1.3‐fold stimulation index in STZ vs. control, P < 0.05) in addition to cellular DNA recovery (57.6 ± 4.4%, P < 0.05). Total cellular insulin content was significantly reduced in NPI exposed to either cytokines (56.6 ± 8.1%) or STZ (45.7 ± 1.6%) compared to controls (P < 0.05). Interestingly, both STZ and cytokines did not appear to negatively affect NPI function post‐transplant.Conclusions:  The potent nitric oxide generating cytotoxin STZ is able to impair in vitro NPI beta cell insulin release whereas human cytokines (IL‐1β, TNFα, IFNγ) do not affect the secretory response nor are they cytotoxic in vitro. These results may have implications for the development of anti‐rejection protocols to be used in clinical NPI xenotransplants.
Effects of pH, Sodium Bicarbonate, Cryoprotectants and Foetal Bovine Serum on the Cryopreservation of European Eel Sperm
Authors: Garzón DL , Peñaranda DS , Pérez L , Marco‐Jiménez F , Espert X , Müller T , Jover M , Asturiano JF 
Published: September 2007

ContentsThe main objective of the present study was to evaluate the influence of pH and bicarbonate concentration in the activation or inhibition of European eel (Anguillaanguilla) spermatozoa and to evaluate the effect of different cryoprotectants: dimethyl sulphoxide (DMSO), acetamide, ethylene glycol, propanol, glycerol and methanol (MeOH). The effect of these factors was evaluated comparing the percentage of motile cells, the percentage of alive cells (by Hoechst staining) and the spermatozoa morphometry pre‐ and post‐cryopreservation (by computer‐assisted morphology analysis). Based on the above findings, three cryoprotectants (DMSO, MeOH and glycerol) were chosen and evaluated in two media (P1 and P1 modified) with different concentrations of NaHCO3 and in the presence or absence of foetal bovine serum (FBS). The effect of these factors was evaluated comparing the percentage of alive and motile cells post‐cryopreservation. DMSO was the cryoprotectant showing better results in relation to the percentage of spermatic alive cells post‐freezing and caused a smaller modification of the head spermatozoa morphology. The combination of P1‐modified medium with DMSO and containing FBS increased slightly but significantly the percentage of motile spermatozoa post‐cryopreservation.
Noradrenergic Control of Arginine Vasopressin Release from the Ewe Hypothalamus In Vitro: Sensitivity to Oestradiol
Authors: Ghuman SPS , Prabhakar S , Smith RF , Dobson H 
Published: September 2007

ContentsThe present study aims at ascertaining the influence of α1‐adrenoreceptors on arginine vasopressin (AVP) release in vitro and determine whether E2 modulates the α1‐adrenoreceptor and AVP interaction. Ten minutes after ewe killing, sagittal midline hypothalamic slices (from the anterior preoptic area to the mediobasal hypothalamus with the median eminence, 2 mm thick, 2 per sheep) were dissected, placed in oxygenated minimum essential media‐α (MEM‐α) at 4°C and within 2 h were singly perifused at 37°C with oxygenated MEM‐α (pH 7.4; flow rate 0.15 ml/min), either with or without E2 (24 pg/ml). After 4 h equilibration, 10 min fractions were collected for 4 h interposed with 10 min exposure at 60 min to a specific α1‐adrenoreceptor agonist or antagonist at various doses (0.1–10 mm). At the end of all perifusions, slices responded to KCl (100 mm) with AVP efflux (p < 0.05). Release of AVP was enhanced (p < 0.05) by the α1‐adrenoreceptor agonist (methoxamine 10 mm; no E2, n = 7 perifusion chambers: from 14.3 ± 2.7 to 20.9 ± 3.9, with E2, n = 10: from 10.7 ± 1.2 to 18.4 ± 3.4 pg/ml) or the antagonist (thymoxamine 10 mm; no E2, n = 5: from 9.5 ± 3.1 to 30.4 ± 6.0, with E2, n = 10: from 10.8 ± 0.9 to 39.1 ± 6.3 pg/ml). With the agonist, the response occurred only at 80 min (p < 0.05) both in the presence and absence of E2. Whereas, after the antagonist, values were higher (p < 0.05) throughout the post‐treatment period (80–170 min) without E2, but declined by 150 min in the presence of E2. Furthermore, the response to the α1‐adrenoreceptor antagonist was greater (p < 0.05; 90–140 min) than the agonist only in the presence of E2. In conclusion, these results reveal direct α1‐adrenoreceptor‐mediated control of the hypothalamic AVP neuronal system which is modulated by E2.
EFFECT OF HYDROGEN SULPHIDE ON β‐AMYLOID‐INDUCED DAMAGE IN PC12 CELLS
Authors: Tang Xiao‐Qing , Yang Chun‐Tao , Chen Jing , Yin Wei‐Lan , Tian Shao‐Wen , Hu Bi , Feng Jian‐qiang , Li Yuan‐Jian 
Published: September 2007

SUMMARY

Hydrogen sulphide (H2S) is a well‐known cytotoxic gas. Recently, H2S has been shown to protect neurons against oxidative stress caused by glutamate, peroxynitrite and HOCl. Considerably lower H2S levels have been reported in the brain of Alzheimer's disease (AD) patients with accumulation of β‐amyloid (Aβ).
The aim of present study was to explore the cytoprotection by H2S against Aβ25–35‐induced apoptosis and the molecular mechanisms underlying this effect in PC12 cells.
Our findings indicated that Aβ25–35 significantly reduced cell viability and induced apoptosis of PC12 cells, along with dissipation of the mitochondrial membrane potential (MMP) and overproduction of reactive oxygen species (ROS).
Sodium hydrosulphide (NaHS), an H2S donor, protected PC12 cells against Aβ25–35‐induced cytotoxicity and apoptosis not only by reducing the loss of MMP, but also by attenuating the increase in intracellular ROS.
The results of the present study suggest that the cytoprotection by H2S is related to the preservation of MMP and attenuation of Aβ25–35‐induced intracellular ROS generation. These findings could significantly advance therapeutic approaches to the neurodegenerative diseases that are associated with oxidative stress, such as AD.
INVOLVEMENT OF SOMATOSTATIN RECEPTOR SUBTYPES IN MEMBRANE ION CHANNEL MODIFICATION BY SOMATOSTATIN IN PITUITARY SOMATOTROPES
Authors: Yang Seung‐Kwon , Chen Chen 
Published: September 2007

SUMMARY

Growth hormone (GH) secretion from pituitary somatotropes is mainly regulated by two hypothalamic hormones, GH‐releasing hormone (GHRH) and somatotrophin releasing inhibitory factor (SRIF).
Somatotrophin releasing inhibitory factor inhibits GH secretion via activation of specific membrane receptors, somatostatin receptors (SSTRs) and signalling transduction systems in somatotropes.
Five subtypes of SSTRs, namely SSTR1, 2, 3, 4 and 5, have been identified, with the SSTR2 subtype divided into SSTR2A and SSTR2B. All SSTRs are G‐protein‐coupled receptors.
Voltage‐gated Ca2+ and K+ channels on the somatotrope membrane play an important role in regulating GH secretion and SRIF modifies both channels to reduce intracellular free Ca2+ concentration and GH secretion.
Using specific SSTR subtype‐specific agonists, it has been found that reduction in Ca2+ currents by SRIF is mediated by SSTR2 and an increase in K+ currents is mediated by both SSTR2 and SSTR4 in rat somatotropes.
REVIEW ARTILCE: Cell therapy and stem cells in animal models of motor neuron disorders
Authors: Hedlund Eva , Hefferan Michael. P. , Marsala Martin , Isacson Ole 
Published: September 2007

AbstractAmyotrophic lateral sclerosis (ALS), spinal bulbar muscular atrophy (or Kennedy's disease), spinal muscular atrophy and spinal muscular atrophy with respiratory distress 1 are neurodegenerative disorders mainly affecting motor neurons and which currently lack effective therapies. Recent studies in animal models as well as primary and embryonic stem cell models of ALS, utilizing over‐expression of mutated forms of Cu/Zn superoxide dismutase 1, have shown that motor neuron degeneration in these models is in part a non cell‐autonomous event and that by providing genetically non‐compromised supporting cells such as microglia or growth factor‐excreting cells, onset can be delayed and survival increased. Using models of acute motor neuron injury it has been shown that embryonic stem cell‐derived motor neurons implanted into the spinal cord can innervate muscle targets and improve functional recovery. Thus, a rationale exists for the development of cell therapies in motor neuron diseases aimed at either protecting and/or replacing lost motor neurons, interneurons as well as non‐neuronal cells. This review evaluates approaches used in animal models of motor neuron disorders and their therapeutic relevance.