bluuebunny/crossref_metadata_2025_split huggingface dataset:
Human subcutaneous tissue distribution of fluconazole: comparison of microdialysis and suction blister techniques
Authors: Sasongko Lucy , Williams Kenneth M. , Day Richard O. , McLachlan Andrew J. 
Published: October 2003

Aims  To investigate uptake of fluconazole into the interstitial fluid of human subcutaneous tissue using the microdialysis and suction blister techniques.Methods  A sterile microdialysis probe (CMA/60) was inserted subcutaneously into the upper arm of five healthy volunteers following an overnight fast. Blisters were induced on the lower arm using gentle suction prior to ingestion of a single oral dose of fluconazole (200 mg). Microdialysate, blister fluid and blood were sampled over 8 h. Fluconazole concentrations were determined in each sample using a validated HPLC assay. In vivo recovery of fluconazole from the microdialysis probe was determined in each subject by perfusing the probe with fluconazole solution at the end of the 8 h sampling period. Individual in vivo recovery was used to calculate fluconazole concentrations in subcutaneous interstitial fluid. A physiologically based pharmacokinetic (PBPK) model was used to predict fluconazole concentrations in human subcutaneous interstitial fluid.Results  There was a lag‐time (approximately 0.5 h) between detection of fluconazole in microdialysate compared with plasma in each subject. The in vivo recovery of fluconazole from the microdialysis probe ranged from 57.0 to 67.2%. The subcutaneous interstitial fluid concentrations obtained by microdialysis were very similar to the unbound concentrations of fluconazole in plasma with maximum concentration of 4.29 ± 1.19 µg ml−1 in subcutaneous interstitial fluid and 3.58 ± 0.14 µg ml−1 in plasma. Subcutaneous interstitial fluid‐to‐plasma partition coefficient (Kp) of fluconazole was 1.16 ± 0.22 (95% CI 0.96, 1.35). By contrast, fluconazole concentrations in blister fluid were significantly lower (P < 0.05, paired t‐test) than unbound plasma concentrations over the first 3 h and maximum concentrations in blister fluid had not been achieved at the end of the sampling period. There was good agreement between fluconazole concentrations derived from microdialysis sampling and those estimated using a blood flow‐limited PBPK model.Conclusions  Microdialysis and suction blister techniques did not yield comparable results. It appears that microdialysis is a more appropriate technique for studying the rate of uptake of fluconazole into subcutaneous tissue. PBPK model simulation suggested that the distribution of fluconazole into subcutaneous interstitial fluid is dependent on tissue blood flow.
The effects of KT3‐671, a new angiotensin II (AT 1) receptor blocker in mild to moderate hypertension
Authors: Patterson D. , Webster J. , McInnes G. , Brady A. , MacDonald T. 
Published: October 2003

Aims  To compare the antihypertensive effect, and tolerability and safety of once daily doses of KT3‐671 with that of placebo in patients with mild to moderate uncomplicated essential hypertension.Methods  A randomised, multicentre, double blind, parallel‐group comparison of KT3‐671 with placebo. Hypertensive patients [Ambulatory Blood Pressure Monitoring (ABPM), mean daytime DBP > 90 mmHg, Office sitting mean DBP 95‐114 after a 7–28 day washout period] entered a 2‐week, single blind, run‐in phase. Patients eligible for the double‐blind phase were randomised to receive KT3‐671 40 mg, 80 mg, 160 mg or placebo once daily over 4 weeks. The primary end‐point was trough mean sitting office DBP. The study had 90% power to detect a 5 mmHg change between treatments and placebo at the 5% level of significance. The secondary end‐points were 24 hour, daytime and night time mean ABPM.Results  Office DBP was significantly lower with KT3‐671 40 mg but not the other 2 dosage groups (−3.2; 95% CL −6.1 : −0.3 P < 0.03). Office SBP was significantly reduced with all dosage groups (40 mg −5.9, 95% CL −11 : −0.9; 80 mg −4.9, 95% CL −9.9 : 0.1 and 160 mg −5.7, 95% CL −10.8 : −0.7 P < 0.05). All doses of KT3‐671 reduced systolic and diastolic ABPM. The number of patients with treatment related adverse events were comparable to placebo (38.8% KT3‐671 vs 32.8% placebo). There was some evidence of a dose‐response relationship with fall in nocturnal ABPM.Conclusions  Oral KT3‐671 was well tolerated. KT3‐671 reduced office systolic BP at all doses and diastolic BP at some of the doses. Due to greater precision and power, the falls in mean ambulatory systolic and diastolic pressure were all significantly lower than placebo.
Root‐canal shaping with manual and rotary Ni‐Ti files performed by students
Authors: Sonntag D. , Delschen S. , Stachniss V. 
Published: October 2003

AbstractAim  To investigate root‐canal shaping with manual and rotary Ni‐Ti files performed by students.Methodology  Thirty undergraduate dental students prepared 150 simulated curved root canals in resin blocks with manual Ni‐Ti files with a stepback technique and 450 simulated curved canals with rotary Ni‐Ti files with a crowndown technique. Incidence of fracture, preparation length, canal shape and preparation time were investigated. Questionnaires were then issued to the students for them to note their experience of the two preparation methods.Results  Zips and elbows occurred significantly (P < 0.001) less frequently with rotary than with manual preparation. The correct preparation length was achieved significantly (P < 0.05) more often with rotary files than with manual files. Instrument fractures were recorded in only 1.3% of cases with both rotary and manual preparation. The mean time required for manual preparation was significantly (P < 0.001) longer than that required for rotary preparation. Prior experience with a hand preparation technique was not reflected in an improved quality of the subsequent rotary preparation. Approximately 83% of the students claimed to have a greater sense of security in rotary than in manual preparation. Overall 50% felt that manual and engine‐driven preparation should be given equal status in undergraduate dental education.Conclusions  Inexperienced operators achieved better canal preparations with rotary instruments than with manual files. No difference in fracture rate was recorded between the two systems.
The effect of cleaning procedures on fracture properties and corrosion of NiTi files
Authors: O'Hoy P. Y. Z. , Messer H. H. , Palamara J. E. A. 
Published: October 2003

AbstractAim  To evaluate the effect of repeated cleaning procedures on fracture properties and corrosion of nickel‐titanium (NiTi) files.Methodology  New NiTi instruments were subjected to 2, 5 and 10 cleaning cycles with the use of either diluted bleach (1% NaOCl) or Milton's solution (1% NaOCl plus 19% NaCl) as disinfectant. Each cleaning cycle consisted of scrubbing, rinsing and immersing in NaOCl for 10 min followed by 5 min of ultrasonication. Files were then tested for torsional failure and flexural fatigue, and observed for evidence of corrosion using scanning electron microscope (SEM). Four brands of NiTi files were immersed in either Milton's solution or diluted bleach overnight and evaluated for corrosion.Results  Up to 10 cleaning cycles did not significantly reduce the torque at fracture or number of revolutions to flexural fatigue (P > 0.05, two‐way anova), although decreasing values were noted with increasing number of cleaning cycles using Milton's solution. No corrosion was detected on the surface of these files. Files immersed in 1% NaOCl overnight displayed a variety of corrosion patterns. The extent of corrosion was variable amongst different brands of files and amongst files in each brand. Overall, Milton's solution was much more corrosive than diluted bleach. Corrosion of file handles was often extreme.Conclusions  Files can be cleaned up to 10 times without affecting fracture susceptibility or corrosion, but should not be immersed in NaOCl overnight. Milton's solution is much more corrosive than bleach with the same NaOCl concentration.
Effect of different irrigation solutions and calcium hydroxide on bacterial LPS
Authors: Tanomaru J. M. G. , Leonardo M. R. , Tanomaru Filho M. , Bonetti Filho I. , Silva L. A. B. 
Published: October 2003

AbstractAim  To evaluate the effect of biomechanical preparation with different irrigating solutions and calcium hydroxide dressing in dog root canals containing bacterial endotoxin (lipopolysaccharides; LPS).Methodology  One hundred and forty premolar roots from seven dogs were filled with Escherichia coli LPS for 10 days (three roots were lost during histological processing). The following irrigating solutions were used for biomechanical preparation: 1% (group I, n = 20), 2.5% (group II, n = 19) and 5% sodium hypochlorite (group III, n = 19), 2% chlorhexidine digluconate (group IV, n = 20) and physiological saline solution (group V, n = 19). In group VI (n = 20), the LPS solution was maintained in the root canal during the entire experiment and in group VII (n = 20), after biomechanical preparation with saline solution, the root canals were filled with a calcium hydroxide dressing (Calen; control). After 60 days, the animals were sacrificed and the following parameters of periapical disease were evaluated: (a) inflammatory infiltrate, (b) periodontal ligament thickness, (c) cementum resorption and (d) bone resorption. Scores were given and data were analysed statistically with the Kruskal–Wallis and Dunn tests (P < 0.05).Results  Histopathological evaluation showed that groups I–VI had more inflammatory infiltrate, greater periodontal ligament thickening and greater cementum and bone resorption (P < 0.05) compared to group VII, which received the calcium hydroxide intracanal dressing.Conclusions  Biomechanical preparation with the irrigating solutions did not inactivate the effects of the endotoxin but the calcium hydroxide intracanal dressing did appear to inactivate the effects induced by the endotoxin in vivo.
Bacterial status in root‐filled teeth exposed to the oral environment by loss of restoration and fracture or caries – a histobacteriological study of treated cases
Authors: Ricucci D. , Bergenholtz G. 
Published: October 2003

AbstractAim  To describe histological and microbiological findings in teeth where root fillings had been exposed to caries and the oral environment for a prolonged period.Methodology  For inclusion in the study, only teeth with a follow‐up period of 3 years or more and those that had been without proper restoration for at least a period of 3 months were considered. Some root fillings had been without restoration for several years. In all, 39 roots representing 32 teeth were examined by histology.Results  The majority of the specimens were without a discernible periapical bone lesion as assessed by radiography. Osteolytic lesions were seen with five roots. Longitudinal tissue sections stained with a modified Brown/Brenn staining technique revealed presence of stainable bacteria in abundance at the canal entrance and in dentinal tubules but were absent mid‐root and apically in all but two specimens. Soft tissue attached to the root tip and in apical ramifications displayed distinct inflammatory cell infiltrates, suggesting microbial exposure in 7 of the 39 roots examined. In all other specimens, inflammatory cell infiltrates were either nonexistent or sparse and then associated with extruded sealer material.Conclusions  Well‐prepared and filled root canals resist bacterial penetration even upon frank and long‐standing oral exposure by caries, fracture or loss of restoration.
Root‐canal preparation with FlexMaster: canal shapes analysed by micro‐computed tomography
Authors: Hübscher W. , Barbakow F. , Peters O. A. 
Published: October 2003

AbstractAim  To evaluate the relative performance of FlexMaster nickel–titanium instruments shaping maxillary molar root canals in vitro.Methodology  Extracted human maxillary molars were scanned, before and after root‐canal shaping, with FlexMaster, employing micro‐computed tomography (µCT) at a resolution of 36 µm. Canals were three‐dimensionally reconstructed and evaluated for volume, surface area, ‘thickness’ (diameter), canal transportation and prepared surface. Based on median canal volume, the canals were divided into ‘wide’ and ‘constricted’ groups. Comparisons were made between mesiobuccal (mb), distobuccal (db) and palatal (p), as well as ‘wide’ and ‘constricted’ canals, using anova and Scheffé post‐hoc tests.Results  Volume and surface area increased significantly and similarly in mb, db and p canals, and no gross preparation errors were found. Mean root‐canal diameters, 5 mm coronal to the apex, increased from 0.45 to 0.65 mm, from 0.41 to 0.56 mm and from 0.79 to 0.85 mm for mb, db and p canals, respectively. Apical canal transportation ranged from 0.01 to 0.29 mm and was independent of canal type; ‘wide’ canals had a significantly higher (P < 0.05) proportion of unprepared surfaces than ‘constricted’ canals had.Conclusions  FlexMaster instruments shaped curved and narrow root canals in maxillary molars to sizes 40 and 45 without significant shaping errors. Canal anatomy had an insignificant impact on preparation, indicating that FlexMaster instruments were able to shape ‘constricted’ canals as well as ‘wide’ ones.
Induction of interleukin‐8 gene expression by black‐pigmented Bacteroides in human pulp fibroblasts and osteoblasts
Authors: Yang L.‐C. , Huang F.‐M. , Lin C.‐S. , Liu C.‐M. , Lai C.‐C. , Chang Y.‐C. 
Published: October 2003

AbstractAim  To investigate the effect of black‐pigmented Bacteroides on the expression of interleukin (IL)‐8 gene in human pulp fibroblasts and osteoblasts.Methodology  The supernatants of Porphyromonas endodontalis, P. gingivalis and Prevotella intermedia were used to evaluate IL‐8 gene expression in human pulp fibroblasts and osteoblasts. The levels of mRNAs were measured by the quantitative reverse transcriptase‐polymerase chain reaction (RT‐PCR) analysis.Results  Investigations of the time‐dependence of IL‐8 mRNA expression in black‐pigmented Bacteroides‐treated pulp fibroblasts and osteoblasts revealed a rapid accumulation of the transcript after 2 h of exposure, and remained elevated throughout the 24‐h incubation period. In addition, IL‐8 mRNA gene expression was also found in human osteoblasts stimulated with black‐pigmented Bacteroides. However, black‐pigmented Bacteroides was found to be more effective in the induction of IL‐8 mRNA gene expression in osteoblasts than in pulp fibroblasts (P < 0.05).Conclusions  Black‐pigmented Bacteroides are capable of amplifying the local immune response and promoting pulpal/periapical tissue inflammation by stimulating pulp fibroblasts and osteoblasts to express IL‐8.
End‐to‐end fusion of linear deleted chromosomes initiates a cycle of genome instability in Streptomyces ambofaciens
Authors: Wenner Thomas , Roth Virginie , Fischer Gilles , Fourrier Céline , Aigle Bertrand , Decaris Bernard , Leblond Pierre 
Published: October 2003

SummaryTwo mutant strains harbouring a linear chromosome whose size reached 13 Mb (versus approximately 8 Mb for the wild type) were characterized. This chromosomal structure resulted from the fusion in inverted orientation of two chromosomes partially deleted on the same arm. The fusion occurred by illegitimate recombination between 6 bp repeats. This chromosomal structure was inherited in strict association with a high level of genetic instability (30% of mutants in a single progeny, phenomenon also called hypervariability) and chromosomal instability. In contrast, derivatives, which did not retain the chromosome fusion, showed a wild‐type‐like instability frequency (c. 1%). Stabilization of the chromosomal structure occurred by chromosome arm replacement or circularization. A high variability of the terminal inverted repeat (TIR) length in the rescued chromosomes (from 5 kb to approximately 1.4 Mb for linear derivatives) was observed. Mutant lineages harbouring the chromosomal fusion are characterized by a highly heterogeneous distribution of DNA in the spores, by the presence of spores without DNA as well as aberrant sporulation figures, and by the production of spores with a low germination rate. The wild‐type characteristics were restored in the descendants, which lost the chromosomal fusion. Thus, the fusion of deleted chromosomes initiates a cycle of chromosome instability sharing several levels of analogy with the behaviour of dicentric chromosomes in eukaryotes. We propose that the high instability of the fused chromosomes results from the duplication of a region involved in partitioning of the chromosomes (parAB‐oriC ).
Vibrio cholerae H‐NS domain structure and function with respect to transcriptional repression of ToxR regulon genes reveals differences among H‐NS family members
Authors: Nye Melinda B. , Taylor Ronald K. 
Published: October 2003

SummaryH‐NS is an abundant bacterial protein involved in transcriptional silencing of a variety of environmentally responsive genes during growth under non‐permissive conditions. We have previously demonstrated a direct role for H‐NS in the negative modulation of expression of several genes within the ToxR virulence regulon of Vibrio cholerae. Here we have undertaken extensive mutagenesis of the structural and functional domains of the H‐NS protein to determine the contribution of each to the regulation of gene expression. Insertions within, or truncations of, the C‐terminal conserved DNA‐binding domain prevent repression of toxT and ctx, as expected. Dominant negative experiments demonstrate that V. cholerae H‐NS represses gene expression as an oligomeric protein. Hydrophobic coiled–coil interactions have been shown to provide oligomerization capability in other H‐NS orthologues. We used site‐directed mutagenesis to construct altered V. cholerae H‐NS proteins, including an extensive internal deletion within the predicted coiled–coil domain. Remarkably, these proteins were competent to repress gene expression and to form oligomers. Chimeric H‐NS proteins, using sequences from both Escherichia coli and V. cholerae H‐NS orthologues, revealed that V. cholerae H‐NS possesses a second oligomerization domain in the N‐terminal 24 amino acids of the protein. Overall, our results suggest DNA binding and protein oligomerization, provided by either the central coiled–coil or N‐terminal domain, are required for repression of promoters responsive to H‐NS within the ToxR regulon.
Transformation of Streptococcus pneumoniae relies on DprA‐ and RecA‐dependent protection of incoming DNA single strands
Authors: Bergé Mathieu , Mortier‐Barrière Isabelle , Martin Bernard , Claverys Jean‐Pierre 
Published: October 2003

SummarySeventy‐five years after the discovery of transformation with Streptococcus pneumoniae, it is remarkable how little we know of the proteins that interact with incoming single strands in the early processing of transforming DNA. In this work, we used as donor DNA in transformation a radioactively labelled homologous fragment to examine the fate of the single‐stranded (ssDNA) products of uptake in cells mutant for DprA or RecA, two proteins essential for transformation. Fifteen minutes after uptake, the labelling of specific chromosomal restriction fragments that demonstrated homologous integration in the wild type was not detected in dprA or recA cells, indicating that in the mutants incoming ssDNA could not be processed into recombinants. Investigation of the fate of donor label 1 min after uptake revealed that incoming ssDNA was immediately degraded in the absence of DprA or RecA. Our results demonstrate that incoming ssDNA requires active protection prior to the RecA‐driven search for homology and that both DprA and RecA are needed for this protection.
Multiple mechanisms for choline transport and utilization in Haemophilus influenzae
Authors: Fan Xin , Pericone Christopher D. , Lysenko Elena , Goldfine Howard , Weiser Jeffrey N. 
Published: October 2003

Summary Haemophilus influenzae obtains choline from either its growth medium or host cell membrane lipids and expresses it on its lipopolysaccharide (LPS) in the form of phosphorylcholine (ChoP), which contributes to its pathogenesis by mimicry of host cell molecules. Two genes (licB and betT) revealed by whole genomic analysis as encoding potential choline transporters were tested for their role in LPS‐ChoP synthesis. The betT gene in H. influenzae is similar to betT in Escherichia coli, which functions in choline transport for the generation of betaine in osmoprotection. The licB gene has homology to bacterial permeases including betT and is encoded in the lic1 locus, which is essential for the expression of LPS‐ChoP. In the presence of high concentrations of choline, neither licB nor betT were necessary for expression of LPS‐ChoP raising the possibility that other unidentified choline uptake mechanisms may exist in this species. However, under choline limiting conditions, including growth in human nasal airway surface fluid, the licB, but not betT, gene was required for choline transport and synthesis of LPS‐ChoP suggesting that LicB functions as a high affinity choline permease. The betT, but not licB, gene was shown to function in osmoprotection in H. influenzae, similar to the role of betT in E. coli. Further analysis demonstrated growth condition dependent differences in the regulation of transcription of the licB and betT genes. We conclude that H. influenzae may have multiple mechanisms for choline uptake and distinct pathways for choline utilization in LPS‐ChoP biosynthesis and osmoregulation.
Error‐prone DNA polymerase IV is controlled by the stress‐response sigma factor, RpoS, in Escherichia coli
Authors: Layton Jill C. , Foster Patricia L. 
Published: October 2003

SummaryAn insertion in rpoS, which encodes the general stress response sigma factor σ38, was isolated as an antimutator for ‘stationary‐phase’ or ‘adaptive’ mutation. In the rpoS mutant strain the levels of error‐prone DNA polymerase Pol IV were reduced. Pol IV is encoded by the dinB gene, and the amount of its transcript was also reduced in rpoS mutant cells. In wild‐type cells, the levels of Pol IV increased in late stationary phase and stayed elevated for several days of continuous incubation, whereas in rpoS defective cells Pol IV was not induced and declined during prolonged incubation. Even in cells missing LexA, the repressor of dinB, maximum Pol IV expression required RpoS. These results suggest that induction of Pol IV is part of a cellular response to starvation and other stresses.
Legionella pneumophila CsrA is a pivotal repressor of transmission traits and activator of replication
Authors: Molofsky Ari B. , Swanson Michele S. 
Published: October 2003

Summary Legionella pneumophila can replicate inside amoebae and also alveolar macrophages to cause Legionnaires’ Disease in susceptible hosts. When nutrients become limiting, a stringent‐like response coordinates the differentiation of L. pneumophila to a transmissive form, a process mediated by the two‐component system LetA/S and the sigma factors RpoS and FliA. Here we demonstrate that the broadly conserved RNA binding protein CsrA is a global repressor of L. pneumophila transmission phenotypes and an essential activator of intracellular replication. By analysing csrA expression and the phenotypes of csrA single and double mutants and a strain that expresses csrA constitutively, we demonstrate that, during replication in broth, CsrA represses every post‐exponential phase phenotype examined, including cell shape shortening, motility, pigmentation, stress resistance, sodium sensitivity, cytotoxicity and efficient macrophage infection. At the transition to the post‐exponential phase, LetA/S relieves CsrA repression to induce transmission phenotypes by both FliA‐dependent and ‐independent pathways. For L. pneumophila to avoid lysosomal degradation in macrophages, CsrA repression must be relieved by LetA/S before phagocytosis; conversely, before intracellular bacteria can replicate, CsrA repression must be restored. The reciprocal regulation of replication and transmission exemplified by CsrA likely enhances the fitness of microbes faced with fluctuating environments.