bluuebunny/crossref_metadata_2025 huggingface dataset:
A comparison of the apical dye penetration patterns shown by methylene blue and India ink in root‐filled teeth
Authors: AHLBERG K. M. F. , ASSAVANOP P. , TAY W. M.
Published: September 2007

This study compared the linear leakage patterns shown by 5% aqueous solution of methylene blue (MB) and India ink (II).

One‐hundred and twenty‐five roots with single canals from extracted human teeth were used. The canals were cleaned and shaped using the step‐back technique under copious irrigation. Three groups were arranged to receive root fillings of gutta‐percha and one of three proprietary sealers using standard lateral condensation techniques: Sealapex (40 roots), Tubli‐Seal (40 roots) and Ketac‐Endo (20 roots). The remaining roots were used as controls: positive with gutta‐percha and no sealer and negative with the apices sealed with nail varnish. The roots were randomly selected for 7‐day immersion in either MB or II, then sectioned longitudinally; dye penetration was assessed using a Wild Leitz stereomicroscope.

In all groups MB showed more penetration than II. The results were statistically significant at the P= 0.01 level, with the exception of the positive control groups. Negative controls showed no penetration.

It is concluded that MB, which has a low molecular weight penetrated more deeply along root canal fillings than II, which has a large particle size.
Leaving the pulp chamber open for drainage has no effect on the complications of root canal therapy.
Authors: TJÄDERHANE L. S. , PAJARI U. H. , AHOLA R. H. , BÄCKMAN T. K. , HIETALA E. L. , LARMAS M. A.
Published: September 2007

In this retrospective study the effects of different kinds of emergency treatments on flare‐ups and other complications were examined. A total of 197 teeth received emergency treatment after diagnosis at the beginning of the root canal therapy; in 103 the pulp chamber was left open for drainage of pus, 35 were treated with dexamethasone sodium phosphate, and 59 with various other medicaments, followed by routine root canal treatment. In all, 404 teeth received root canal treatment without emergency treatment. If symptoms occurred during treatment, flare‐up was said to be present. If a periapical radiolucency was found, long‐term calcium hydroxide treatment was used: no sign of periapical healing radiographically after 6 months was described as a complication. The percentage of teeth with no complications varied from 72.2% (dexamethasone) to 78.9% (other modification) and the results showed no differences between the groups in the teeth with no complications, flare‐ups or other complications. The number of bacteria detected with Gram's staining was higher in the teeth which were left open. In conclusion, leaving the pulp chamber open for drainage had no effect on the incidence of flare‐ups or other complications.
Reliability of reduced air pressure methods used to assess the apical seal
Authors: RODA R. S. , GUTMANN J. L.
Published: September 2007

The reliability of two commonly used methods of sealability testing, dye leakage under normal atmospheric pressure and dye leakage in a partial vacuum, was tested using a repeated studies design. Forty extracted teeth were instrumented and obturated using lateral condensation of gutta‐percha and Sealapex™ sealer. One‐half of the teeth were placed in India ink under normal atmospheric pressure and the other half underwent air evacuation before immersion in the ink. After 24 h the teeth were removed from the ink and rendered transparent for linear leakage analysis. A second study, repeated within the exact parameters of the first, was performed approximately 1 month later. Mann‐Whitney U tests indicated that there was no significant difference (P>0.05) between the air and vacuum groups or within each group (air or vacuum) between trials, indicating that the methodology is repeatable and that application of reduced air pressure did not enhance reliability. A large majority of the teeth placed under partial vacuum showed evidence of vacuum‐induced artefacts that may negate the value of vacuum as a research tool.
The effect of an Nd–YAG pulsed laser on the cleaning of the root canal and the formation of a fused apical plug
Authors: SAUNDERS W. P. , WHITTERS C. J. , STRANG R. , MOSELEY H. , PAYNE A. P. , McGADEY J.
Published: September 2007

A Neodyminium‐yttrium aluminium garnet (Nd–YAG) pulsed laser was used in vitro to determine whether various laser energy levels from 0.75 W to 1.7 W at 15 pulses s−1 (pps) were able to (i) remove debris from the walls of prepared root canals (ii) remove pulpal tissue from unprepared canals and (iii) create a fused apical plug from dentine chips, hydroxyapatite (HAP) or low‐fusing dental porcelain. Single‐rooted teeth were sectioned at the amelocemental junction and the crowns discarded. The root canals of 50 teeth were prepared chemomechanically and allocated to four groups of 10 teeth for laser treatment. One group was left unlased as a control. After lasing, the teeth were split longitudinally, stained and examined for residual debris. Results showed that there was no statistically significant difference between the groups (P < 0.05). A further 20 teeth were not prepared and lased in the coronal one‐third of the root canal at different energy levels; five teeth were not lased. The teeth were split and examined as previously. The results showed that lasing cleaned the coronal part of the root canal almost completely of pulpal tissue. In the final part of the study laser energy was applied to dentine chips, HAP and low‐fusing procelain in an attempt to produce a fused apical plug. The laser was unable to melt the dentine chips but some hardening of HAP occurred when combined with blue food‐colouring, with or without glycerine, at energy levels of 1.0 W, at 15 pps for 30 s. Superficial hardening of low‐fusing porcelain occurred at 1.0 W, 15 pps for 30 s which increased when 1.5 W was applied at 15 pps for 30s.
Ultrasonic preparation and obturation of root‐end cavities
Authors: SULTAN M. , FORD T. R. PITT
Published: September 2007

This study evaluated the preparation of root‐end cavities using an ultrasonically activated file, and the obturation of such cavities. In the first part, the root canals of 40 extracted teeth were prepared to size 40 and irrigated with NaOCl and EDTA. The root ends were resected and the teeth inoculated with Enterococcus faecalis, incubated for 10 days and divided into four groups: control; saline irrigation; hand instrumentation performed via a retrograde approach up to size 50 using saline irrigant; ultrasonic instrumentation with prebent size 40 K‐flex file inserted into a Piezon Master using saline irrigant. The teeth were fixed, sectioned longitudinally and viewed under scanning electron microscopy. Bacterial and smear layer scores were obtained at 1, 3, and 5 mm from the resected end. The bacterial scores for control and saline groups were similar; the scores for each instrumentation group were significantly lower than the control group (P<0.001), In addition, there were significantly fewer bacteria in the ultrasonic group compared with the hand instrument group (P<0.001), The smear layer scores for control and saline groups were similar, and significantly lower than in either instrumentation group (P<0.001). In the second part, root‐end cavities were ultrasonically prepared in 20 extracted teeth. Ten cavities were filled with amalgam, and 10 with thermoplasticized gutta‐percha and Grossman s sealer. After 24‐h storage, the root ends were immersed in dye for 48 h. Cross‐sectional slices of the obturated part of the root were evaluated using both light and confocal microscopy for dye leakage along the interface of filling material and dentine. There were no statistical differences between the leakage of amalgam and gutta‐percha root‐end fillings, nor between the two methods of microscopy.
Studies into the microbial spectrum of apical periodontitis
Authors: BRAUNER A. W. , CONRADS G.
Published: September 2007

This study examined the variety of obligate and facultative anaerobic bacterial species recovered from cases of acute apical periodontitis. A total of 19 root canal samples and 24 periapical granuloma samples were taken from patients suffering pain and discomfort. Bacteria were identified by applying the following techniques: culturing on various media, Gram‐staining and using commercially available biochemical test strips. In addition, Prevotella intermedia and Porphyromonas endodontalis were differentiated on a molecular genetic level using species‐specific oligodeoxymicleotide probes. The most frequently identified bacteria were Prevotella intermedia, Bifidobacterium spp., Streptococcus sanguis. Streptococcus milleri‐group and Bacteroides spp. Obligate anaerobes occured at a rate of 82.3%, and the average number of isolates was 6.4 per sample.
Effect of various zinc oxide materials as root‐end fillings on healing after replantation
Authors: FORD T. R. PITT , ANDREASEN J. O. , DORN S.O. , KARIYAWASAM S. P.
Published: September 2007

This study examined the effect of various zinc oxide materials as root‐end fillings of teeth in a replantation model. A total of 35 molar teeth were used from 19 monkeys. After extraction, root ends were resected, the canals contaminated with oral bacteria, root‐end cavities prepared and fillings placed prior to replantation. After 8 weeks the teeth and surrounding jaw were removed and prepared for histological examination. Twelve roots were filled with IRM plus dentine chips, and six with Cavit; the tissue response around root ends filled with these materials as assessed by inflammation was similar to that previously reported to IRM and Super EBA cement and was characterized by little or no inflammation of limited extent. In contrast, more severe inflammation was observed around root ends filled with plain zinc oxide–eugenol or Kalzinol; however, the reaction was neither as severe nor as extensive as that to amalgam root–end fillings. Giant cells were observed most often on the surface of fillings with Cavit and zinc oxide–1eugenol. It is concluded that the tissue response to IRM with or without added dentine, Super EBA and Cavit was similar and mild; it was less severe than that to zinc oxide‐eugenol and Kalzinol. All these materials had a much more favourable response than amalgam.
In vitro study of the indirect action of calcium hydroxide on the anaerobic flora of the root canal
Authors: KONTAKIOTIS E. , NAKOU M. , GEORGOPOULOU M.
Published: September 2007

The aim of this study was to evaluate in vitro a possible mechanism involved in the antimicrobial action of calcium hydroxide, namely absorption of carbon dioxide from the roof canal.

Twenty obligate and 20 facultative anaerobic bacteria isolated from infected root canals and identified to species level were used. For each bacterial species a standard concentration was achieved and 0.1 ml of the inoculum was spread on blood agar plates, which were consecutively incubated in an anaerobic chamber for 5–7 days.

One experimental and one control group were studied: the experimental group included one plate with the bacterial species as well as one open plate containing 32 g calcium hydroxide paste at a mixing ratio of 6:4. Both plates were incubated in an anaerobic chamber for 72 h. The control group included only one plate containing the same bacterial species and was incubated under the same conditions. After a 72‐h incubation, the number of the recovered bacteria were counted in both groups.

Statistical analysis showed that the number of bacteria recovered from the control group was significantly lower than that of the experimental group, but no particular resistance of any bacterial species to calcium hydroxide could be detected. This finding strongly suggests that the ability of calcium hydroxide to absorb carbon dioxide may contribute to its antibacterial activity.
Sickle cell disease: a diagnostic dilemma
Authors: BISHOP K. , BRIGGS P. , KELLEHER M.
Published: September 2007

The case history is described of a patient with sickle cell anaemia who developed a unilateral infarct of the mandible following a sickle cell crisis. The interruption of the blood supply resulted in an anaesthesia of the inferior dental nerve and pulpal necrosis of otherwise sound premolar and molar teeth. The diagnostic and management difficulties of the case are discussed, and recommendations are made for the treatment of such patients in light of the problems encountered.
Dens invaginatus in a mandibular lateral incisor
Authors: KHABBAZ M. G. , KONSTANTAKI M. N. , SYKARAS S. N.
Published: September 2007

A rare case of dens invaginatus involving a non‐carious mandibular lateral incisor with periapical periodontitis is reported. Invaginated teeth present technical difficulties in their clinical management because of their abnormal anatomy. In the present case, non‐surgical root canal therapy was chosen. A one‐year follow‐up clinical and radiographic examination showed a non‐symptomatic tooth with osseous healing proceeding.
Periradicular healing in response to Diaket root‐end filling material with and without tricalcium phosphate
Authors: WILLIAMS S. SNYDER , GUTMANN J. L.
Published: September 2007

The healing of the periradicular tissues was evaluated when the polyvinyl resin Diaket with and without tricalcium phosphate was used as surgical root‐end filling material. Non‐surgical root canal treatment was performed on 56 mandibular premolar roots in mongrel dogs. Following root‐end resection, root‐end cavity preparations were filled with Diaket, the comparative material, or Diaket in combination with tricalcium phosphate, the experimental material. Postsurgically, healing of the tissues adjacent to the filling materials and in the surrounding surgical site were evaluated at 30 and 60 days. There was virtually no statistically significant difference between the experimental and comparative group at or within the 30‐ or 60‐day period with regard to inflammation, connective tissue formation, root‐end encapsulation, cementum formation, or bone apposition. Findings suggest that cementogenesis occurred over both materials. The overall healing of the periradicular tissues was favourable.
Clinical uses of rectified turpentine oil
Authors: KAPLOWITZ G. J.
Published: September 2007

Rectified turpentine oil can be used to soften or dissolve gutta‐percha in the root canal space to facilitate endodontic retreatment or preparation of space for a post. For endodontic retreatment, the turpentine oil can be heated to 71°C which significantly increases its ability to dissolve gutta‐percha. For removing only a portion of the gutta‐percha while leaving the rest intact, as for the preparation of space for a post, the turpentine oil is delivered to the canal at body temperature (37°C).
Sterilization of infected root‐canal dentine by topical application of a mixture of ciprofloxacin, metronidazole and minocycline in situ
Authors: SATO I. , ANDO‐KURIHARA N. , KOTA K. , IWAKU M. , HOSHINO E.
Published: September 2007

The aim of this study was to observe the potential of a mixture of ciprofloxacin, metronidazole and minocycline to kill bacteria in the deep layers of root canal dentine in situ. After the crowns of extracted teeth had been removed, the drug combination (0.5 mg of each drug), or sterile saline, as the control, was placed in the root canals which had been previously irrigated ultra‐sonically with 0.4 m EDTA. The penetration and bactericidal efficacy were estimated by various procedures as follows. (1) A cell suspension of E. coli was placed into small cavities prepared parallel to the root canals on the cut planes of nine single‐rooted teeth. The teeth were then entirely covered with blue inlay wax. At time 0, and at 5h, 24h and 48h after the drug combination had been applied, cells of E. coli were recovered from the cavities by washing the cavities several times with sterile saline solution, and were cultured on the surfaces of heart‐infusion (HI) agar plates. Total colony‐forming units were then counted. Bacterial recoveries decreased with time, and no bacteria were recovered 48 h after application of the drug combination, while bacteria survived in all cases with the controls. (2) After the drug combination or sterile saline had been placed into and sealed in the root canal with blue inlay wax, the teeth were placed into HI agar plates where cells of E. coli had been inoculated. After culturing, a clear zone caused by the inhibition of bacterial growth was observed around the teeth, but not in the control experiment. (3) After sampling infected root dentine of 12 freshly extracted teeth as positive controls, the drug combination (0.5 mg each) was placed in the root canals. No bacteria were recovered from the infected dentine of the root canal wall 24 h after application of the drug combination, except in one case in which a few bacteria were recovered. On the basis of these results, penetration through dentine and antibacterial efficacy of the drug combination can be expected against bacteria infecting the dentine of the root canal wall in situ when the drugs were placed in root canals which had been irrigated ultrasonically.
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

The 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

Roots 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

The 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

This 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

The 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

Root 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

A 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.
Hepatitis B virus polymerase variants associated with entecavir drug resistance in treatment‐naive patients
Authors: Jardi R. , Rodriguez‐Frias F. , Schaper M. , Ruiz G. , Elefsiniotis I. , Esteban R. , Buti M.
Published: September 2007

Summary.  It has been suggested that lamivudine therapy can preselect for hepatitis B virus (HBV) variants associated with resistance to entecavir (ETV) treatment. The aim of this study was to determine the prevalence of HBV variants associated with ETV resistance (rtI169T, rtT184G, rtS202I, rtM250V) in naive patients before and during lamivudine therapy. This retrospective study includes 111 untreated patients with chronic HBV infection, who were later treated with lamivudine therapy for at least 18 months. Serum samples were obtained before and during treatment. Variants related with ETV drug resistance were analysed by sequencing the HBV reverse transcriptase. Prior to lamivudine treatment, three cases (2.7%) had substitutions in the HBV polymerase gene corresponding to variants associated with ETV resistance (rtS202S/I). None of these patients had lamivudine‐resistant variants. During lamivudine treatment, substitutions associated with ETV resistance were detected in 10 (9%) nonresponding patients who had not presented these changes before treatment. In 2/10 cases, these changes were observed before detection of lamivudine‐resistant substitutions. In 10 of 12 nonresponders, one of them with ETV‐related variants prior to treatment, these variants persisted to the end of therapy. Detection of variants related to ETV drug resistance in untreated patients with chronic HBV infection indicates that these variants are present in a significant proportion of the HBV quasispecies. This fact, as well as the emergence of ETV‐resistant variants during lamivudine treatment, should be kept in mind when selecting candidates for ETV therapy.
Association of amino acid variations in the NS5A and E2‐PePHD region of hepatitis C virus 1b with hepatocellular carcinoma
Authors: Hung C.‐H. , Chen C.‐H. , Lee C.‐M. , Wu C.‐M. , Hu T.‐H. , Wang J.‐H. , Yen Y.‐H. , Lu S.‐N.
Published: September 2007

Summary.  NS5A and E2 proteins of the hepatitis C virus (HCV) have the potential to repress protein kinase R (PKR) that exerts a tumour suppressor function. We investigated the relationship between amino acid variations in the NS5A‐PKR‐binding domain and E2‐PKR‐eIF2α phosphorylation homology domain (PePHD) region and the development of hepatocellular carcinoma (HCC) in chronic HCV‐1b patients. In a cross‐sectional, hospital‐based setting, we compared the amino acid sequences of NS5A‐PKR‐binding domain and E2‐PePHD in the sera of 104 chronic hepatitis, 44 cirrhosis and 96 HCC patients. The nucleotide sequences were inferred by direct sequencing of the amplified HCV products and deduced amino acid were compared with the sequence of HCV‐J. By univariate analysis, old age, lower viral load, fewer amino acid substitutions in the NS5A‐PKR‐binding domain (codons 2209–2274) and the interferon sensitivity‐determining region (ISDR; codons 2209–2248), and wild‐type amino acid at codon 2209 and codon 2240 was significantly correlated with HCC, whereas substitutions in the E2‐PePHD was not. Patients with a mutated‐type (≥4) NS5A‐ISDR had a lower prevalence of HCC than those with intermediate or wild type (P < 0.05). Based on stepwise logistic regression analysis, age [odds ratio (OR): 1.132, P < 0.001], viral load (OR: 0.305, P < 0.001) and mutated‐type ISDR (OR: 0.137, P = 0.001) were independently associated with HCC. In conclusion, NS5A‐ISDR variations may play an important role in the development of HCV‐related HCC.
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

Mobile 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

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 > 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

Contents

The 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

Contents

The 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

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

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

Amyotrophic 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.
Modulation of a spinal locomotor network by metabotropic glutamate receptors
Authors: Chapman Rebecca J. , Sillar Keith T.
Published: September 2007

We have explored the potential involvement of the three main classes of metabotropic glutamate receptor in the modulation of a spinal locomotor network using tadpoles of the anuran amphibianXenopus laevis. Selective activation of group I receptors inXenopusembryos and young larvae using the general group I agonist DHPG [(S)‐3,5‐dihyroxyphenylglycine] significantly increased the frequency of swimming and the number of spontaneously occurring swimming episodes, as monitored by extracellular recordings from ventral roots. Group I receptor activation was without significant effect on the duration or amplitude of motor bursts, the duration of swimming episodes, or the head‐to‐tail delay in the propagation of swimming activity. Activation of either group II or group III receptors, however, following bath applications of the specific agonists APDC [(2R,4R)‐aminopyrrolidine‐2,4‐dicarboxylic acid] and L‐AP4 (l‐2‐amino‐4‐phosphonobutanoate), respectively, produced a net inhibitory effect on many of the parameters of fictive swimming at both developmental stages, including a reduction in swimming frequency and episode duration, along with a significant reduction in motor burst amplitude and duration in larval animals only. Applications of selective antagonists provide evidence for activation of all three groups during swimming. The group II and III antagonists EGLU (1‐ethyl‐2‐benzimidazolinone) and MAP4 [(S)‐2‐amino‐2‐methyl‐4‐phosphonobutanoate], respectively, increased, while group I antagonists, CPCCOEt and MPEP, decreased swim frequency. Our findings thus provide evidence for the presence and endogenous activation of three classes of metabotropic glutamate receptor which may function as an intrinsic modulatory control system during fictive swimming inXenopustadpoles.
Gaze pursuit, ‘attention pursuit’ and their effects on cortical activations
Authors: Ohlendorf S. , Kimmig H. , Glauche V. , Haller S.
Published: September 2007

A moving object draws our attention to it and we can track the object with smooth pursuit eye movements (SPEM). Gaze and attention are usually directed to the same object during SPEM. In this study we investigated whether gaze and attention can be divided during pursuit. We explored the cortical control of ocular tracking and attentive tracking and the role of focused and divided attention. We presented a sinusoidally moving target for pursuit and simultaneously a stationary target for fixation. Gaze could be directed to the pursuit target and attention to the fixation target or vice versa, or gaze and attention were directed to the same (moving or stationary) target. We found that gaze (overt) and attentive (covert) pursuit similarly activated the cortical oculomotor network. Gaze pursuit showed higher activations than attentive pursuit. Activations, specific to the dissociation of attention from gaze and independent of eye movements, were found solely in the posterior parietal cortex. A cue indicating a forthcoming attention task activated large parts of the cortical SPEM network, as a kind of preparatory mechanism. We did not find any attention‐related regions outside the well‐known visuo‐oculomotor network. We conclude that attention control during gaze pursuit and gaze fixation occur within the cortical SPEM network, supporting the premotor theory of attention [Rizzolatti, G., Riggio, L., Dascola, I. & Umilta, C. (1987) Neuropsychologia, 25, 31–40].