bluuebunny/crossref_metadata_2025 huggingface dataset:
The ability of 1.23% acidulated phosphate fluoride gel to inhibit simulated endogenous erosion in tooth roots
Authors: Saunders JGC , McIntyre JM
Published: March 2008

Background: Endogenous dental erosion is that produced by contact of gastric acids with tooth structure. It may affect exposed root cementum/ dentine as well as coronal enamel, causing marked loss of mineral. The aim of this study was to determine whether 1.23 per cent acidulated phosphate fluoride gel, if applied to the surface cementum at certain intervals during an erosive acid challenge, could provide any protection against demineralization.

Materials and methods: Roots of preserved extracted human teeth were painted with a water and acid resistant varnish, leaving two windows (3times1mm) of exposed dentine. These were placed in a solution containing 0.06MHCl and 2.2mMCaHPO4, which has been shown to simulate gastric acid when it meets the tooth surface. The roots were placed in the erosive solution unprotected (controls), or subject to APF application for four minutes prior to and every 10, 30 or 120 minutes during the erosive challenge. Roots were removed at either 6 or 12 hours, washed thoroughly and cut into 120μm thick sections. Depths of demineralization were measured using an optical graticule under polarized light microscopy.

Results: A high level of protection was provided when the roots were coated with APF gel every 10 or 30 minutes.

Conclusions: APF gel will partially inhibit endogenous erosion of roots for up to 30 minutes if applied, for example, the night before a morning reflux episode. This should be considered along with other erosion control or reduction procedures for patients suffering from the effects of endogenous erosion.
A concise review of the basic biology and pharmacology of local analgesia
Authors: Subramaniam S. , Tennant M.
Published: March 2008

Local analgesics are the most commonly used group drugs in dental practice. However, due to their frequent use and high margin of safety, often dental practitioners neglect to properly understand the biology and pharmacology of these drugs. This article reviews the basic concepts of pain, pain pathways, the mode of action of local analgesics and factors which affect their usage. Specific details and properties of some currently available solutions are also outlined. A greater understanding of the biology and pharmacology of local anaesthetics will ultimately lead to safer and more effective use in everyday clinical practice.
Dental fear in Australia: who's afraid of the dentist?
Authors: Armfield JM , Spencer AJ , Stewart JF
Published: March 2008

Background: This study aimed to describe both the prevalence of dental fear in Australia and to explore the relationship between dental fear and a number of demographic, socio‐economic, oral health, insurance and service usage variables.

Methods: A telephone interview survey of a random sample of 7312 Australian residents, aged five years and over, from all states and territories. Results: The prevalence of high dental fear in the entire sample was 16.1 per cent. A higher percentage of females than males reported high fear (HF). Adults aged 40–64 years old had the highest prevalence of high dental fear with those adults aged 80+ years old having the least. There were also differences between low fear (LF) and HF groups in relation to socio‐economic status (SES), with people from higher SES groups generally having less fear. People with HF were more likely to be dentate, have more missing teeth, be covered by dental insurance and have a longer time since their last visit to a dentist.

Conclusions: This study found a high prevalence of dental fear within a contemporary Australian population with numerous differences between individuals with HF and LF in terms of socio‐economic, socio‐demographic and self‐reported oral health status characteristics.
Failure to obtain adequate anaesthesia associated with a bifid mandibular canal: a case report
Authors: Lew K. , Townsend G.
Published: March 2008

The inferior alveolar nerve (IAN) block is the most common method for obtaining mandibular anaesthesia in dental practice but it is estimated to have a success rate of only 80 to 85 per cent. Causes of failure include problems with operator technique and anatomical variation between individuals. This case report involves a patient who received IAN blocks on two separate occasions that resulted in only partial anaesthesia of the ipsilateral side of the mandible. Radiographic assessment disclosed the presence of bifid mandibular canals that were present bilaterally and that may have affected the outcomes of the local anaesthetic procedures. Previous studies of bifid mandibular canals are reviewed and suggestions provided that should enable clinicians to differentially diagnose, and then manage, cases where IAN blocks result in inadequate mandibular anaesthesia.
Fluoride content of still bottled water in Australia
Authors: Cochrane NJ , Saranathan S. , Morgan MV , Dashper SG
Published: March 2008

Background: Recently there has been a considerable increase in the consumption of bottled water in Australia. Overseas studies have found the fluoride levels in many bottled waters are well below levels considered optimal for preventing dental caries. This raises the concern that if bottled water is regularly consumed an effective means of preventing dental caries is unavailable. The aim of this study was to determine the fluoride concentration in 10 popular brands of still bottled water currently sold in Australia.

Methods: The fluoride content of water samples were determined using an ion analyser and compared to a fluoride standard.

Results: The fluoride concentration of all bottled waters was less than 0.08ppm. Only three of the 10 brands indicated the fluoride content on their labels. Melbourne reticulated water was found to be fluoridated at 1.02ppm.

Conclusions: All bottled waters tested contained negligible fluoride which justifies the concern that regular consumption of bottled water may reduce the benefits gained from water fluoridation. It is recommended that all bottled water companies should consider stating their fluoride content on their labels. This will inform consumers and dental care providers of the levels of fluoride in bottled water and allow an informed decision regarding consumption of fluoridated versus non‐ fluoridated drinking water.
Comparison of microshear bond strengths of four self‐etching bonding systems to enamel using two test methods
Authors: Foong J. , Lee K. , Nguyen C. , Tang G. , Austin D. , Ch'ng C. , Burrow MF , Thomas DL
Published: March 2008

Background: Recent advances in enamel and dentine adhesive technology have resulted in the emergence of many new adhesive systems. Self‐etching bonding systems do not require a separate etching step and the newest systems are the “all‐in‐one” systems which combine etching, priming and bonding into a single application. This study reports laboratory enamel microshear bond strengths of a self‐etching priming and three all‐in‐one systems and also evaluates two different microshear bond test methods.

Methods: One hundred and nineteen enamel specimens were bonded (0.8mm diameter) with either Clearfil Protect Bond (Kuraray), Xeno III (Dentsply), G Bond (GC) or One‐Up Bond F (Tokuyama) using Palfique Estelite resin composite and stored in 37°C water for seven days. The microshear bond test method used either a blade or wire to apply the shear stress. Results were analysed with one‐way ANOVA and post hoc (Tukey) multiple comparison analysis.

Results: Clearfil Protect Bond demonstrated higher and more consistent bond strengths than Xeno III, G Bond or One‐Up Bond F. The wire method showed much greater reliability in results, with a coefficient of variation half that of the blade method.

Conclusions: All‐in‐one adhesives seem to be less reliable than the two‐step self‐etching priming adhesive when bonding to enamel. Test method can significantly affect results in the microshear bond test method.
Discrimination or discretion? Exploring dentists' views on treating patients with hepatitis C
Authors: Temple‐Smith M. , Jenkinson K. , Lavery J. , Gifford SM , Morgan M.
Published: March 2008

Background: People with hepatitis C (over 259 000 Australians) experience stigma and discrimination, whether perceived or actual, in health care settings. They are less likely to access health care, presenting a major barrier to preventive care and treatment. This study aims to identify factors contributing to such discrimination, barriers to optimal care and strategies to overcome these.

Methods: A purposive sample of 25 Victorian dentists took part in semi‐structured interviews to investigate their experiences and attitudes in providing care to people with hepatitis C. Interviews were taped, transcribed and coded for thematic analysis.

Results: All dentists interviewed were aware of Standard Precautions. However, there were some who changed practices when seeing a client with hepatitis C, suggesting that they lack confidence in Standard Precautions. When prompted, these dentists were concerned that patients may perceive these actions as discriminatory. All participants, including a small minority who expressed negative views about injecting drug users, felt a professional obligation to treat all patients.

Conclusions: Most dentists have appropriate attitudes regarding patients with blood‐borne viruses. However, it is important for dentists to understand how their actions may be interpreted by those who feel sensitive about their status. Dentists need to feel genuinely confident about Standard Precautions and have a realistic view of the infection risk posed by patients with blood‐borne viruses.
An Aboriginal and Torres Strait Islander oral health curriculum framework: development experiences in Western Australia
Authors: Bazen J. , Paul D. , Tennant M.
Published: March 2008

Indigenous oral health is widely acknowledged as paralleling the significant issues faced in general health. It is recognized that as part of the process of addressing these issues, practitioners need to be aware of the complex nature of working in an Indigenous social and cultural context, including issues beyond direct health care services. It is against this backdrop that collaborators from The University of Western Australia's (UWA) Centre for Rural and Remote Oral Health (CRROH) and Centre for Aboriginal Medical and Dental Health (CAMDH) developed a comprehensive, integrated Indigenous Oral Health Curriculum Framework for the Bachelor of Dental Science (BDSc) course. This development was based on the existing framework developed by the Committee of Deans of Australian Medical Schools (CDAMS) for medical education but was tailored to the specific issues and needs of oral health.

Additional consultation with the Oral Health Centre of Western Australia (OHCWA), the School of Indigenous Studies (SIS) as well as Indigenous Australian groups occurred to ensure the development process was inclusive. The inclusion of an Indigenous Oral Health Curriculum Framework in the BDSc will enable UWA dental graduates to practise dentistry in a culturally appropriate manner. The framework provides the structure for students to develop and demonstrate an understanding of Indigenous histories, cultures and social experiences and how these impact on Indigenous peoples' health. It is anticipated that this will foster more positive and culturally secure patient‐practitioner interactions between UWA dental graduates and Indigenous Australians, thereby making it more likely for Indigenous Australians to present for treatment. The increased awareness of Indigenous oral health issues will hopefully encourage more graduates to become involved in the treatment of Indigenous peoples. The combination of these factors could lead to an improvement in oral health outcomes for Australia's Indigenous peoples and a concomitant positive impact on the general health of Indigenous Australians.
Laser‐activated fluoride treatment of enamel against an artificial caries challenge: comparison of five wavelengths
Authors: Vlacic J. , Meyers IA , Kim J. , Walsh LJ
Published: March 2008

Background
: Laser‐activated fluoride (LAF) therapy with 488nm laser energy has been shown previously to increase the resistance of human enamel and dentine to acid dissolution in laboratory models of dental caries. The aims of this study were to examine whether LAF therapy, conducted using a range of wavelengths in the visible and near infrared regions, can protect human dental enamel from an artificial cariogenic challenge.

Materials and methods
: Buccal and lingual surfaces of extracted sound, molar and premolar teeth were used to prepare matched pairs of enamel slabs (N=10 per group). After application of neutral sodium fluoride gel (12300ppm F ion), slab surfaces were lased (energy density 15 J/cm2; spot size 5mm, wavelength 532, 633, 670, 830 or 1064nm), then exposed to an artificial cariogenic challenge for a period of seven days. The Vicker's hardness number (VHN) was recorded before and after laser treatment and again following the cariogenic challenge. Negative controls did not receive laser exposure.

Results
: All wavelengths of laser light examined provided an effective LAF effect, compared with the unlased negative control surfaces.

Conclusion
: Using this in vitro model, we conclude that the action spectrum of the LAF effect extends across the visible and near‐infrared regions of the spectrum.
Profile of the oral health among ambulant older Greek and Italian migrants living in Melbourne
Authors: Mariño R. , Calache H. , Wright C. , Morgan M. , Schofield M. , Minichiello V.
Published: March 2008

Background: Over the last 50 years an increasing number of migrants have settled in Australia. These immigrants now constitute a large proportion of the Australian population, and some research suggests that they may be at high‐risk for oral diseases.

Methods: This paper presents data on the oral health status of a convenience sample of 721 ambulant Greek‐ (n=367) and Italian‐born (n=354) adults aged 55 years or older. The volunteer participants were recruited through ethnic social clubs located in Melbourne, Australia.

Results: The sample was largely a dentate one (83.6 per cent); with a mean DMFS score of 67.5 (s.d. 37.4). Dentate participants had 13 per cent of their restorative care unmet, and 57.3 per cent needed oral hygiene instruction plus removal of stain and hard deposits on their teeth. Almost 8 per cent required complex periodontal therapy and 30 per cent of those fully edentulous were in need of full dentures.

Conclusions: Comparing these findings with existing data on oral health of older adults in Australia, the participants in this study appear to have lower DMFS scores and a higher prevalence of gingivitis, but less need for complex periodontal treatment. Inequalities were apparent in the proportion of unmet restorative and prosthetics needs.
Palatal anaesthesia for the removal of maxillary third molars as practised by oral and maxillofacial surgeons in Australia and New Zealand
Authors: Badcock ME , McCullough MJ
Published: March 2008

Background: Injections of local anaesthetic to the palate are well known to be poorly tolerated. The absolute requirement of a palatal injection for the removal of maxillary third molars has never been investigated. The aim of this study was to document the current practice of palatal anaesthesia for extraction of these teeth with local anaesthesia as practised by oral and maxillofacial surgeons.

Methods: A postal survey was sent via the ANZAOMS office to all oral and maxillofacial surgeons who were members of the Australian and New Zealand Association, a total of 131. A response rate of 64 per cent (n=84) was achieved. The frequency of administration and the factors that determined the decision to administer a palatal injection were assessed, as well as the methods employed for reducing the injection discomfort.

Results: The majority (77 of the 84) “always” gave a palatal injection for the removal of maxillary third molars, four respondents administered an injection “most of the time”, and two respondents “occasionally”. Significantly, one respondent “never” gave a palatal injection. The majority (76 per cent) utilized at least one adjunct in order to reduce the discomfort of the injection.

Conclusions: The results of this survey suggest that for removal of maxillary third molars the requirement of the poorly tolerated palatal injection may not be absolute as conventionally taught and demonstrates the need for further investigation.
Management of tooth resorption
Authors: Heithersay GS
Published: March 2008

A correct diagnosis and an understanding of the aetiology and dynamics of the processes involved in tooth resorption is critical to effective management. Tooth resorptions can be classified as: (1) trauma induced; (2) infection induced; or (3) hyperplastic invasive. Some transient trauma induced resorptions require no treatment but must be carefully monitored to check that there are no complicating issues such as infection. In cases of trauma induced replacement resorption, a multidisciplinary approach is usually necessary to ensure an optimal long‐term solution. Infection induced tooth resorptions require the removal of the invading micro‐organisms by endodontic therapy including intra‐canal medication which can also facilitate repair of the resorbed tooth structure. The hyperplastic invasive tooth resorptions pose considerable challenges in management due to the complexity and aggressive nature of the resorptive process. With careful case selection and complete inactivation of resorptive tissue successful management can be achieved.
The endodontic management of traumatized permanent anterior teeth: a review
Authors: Moule AJ , Moule CA
Published: March 2008

Despite the many journal articles and reviews that have been published regarding the treatment of trauma to teeth, the endodontic management of these injuries is often still not fully understood. The purpose of this review is to establish clear and up‐to‐date guidelines for practitioners who are faced with treating dental injuries on a day‐to‐day basis, based on an assessment of current available scientific information relating to the endodontic management of these injuries.

Treatment is discussed under the headings: infractions, uncomplicated crown fractures, complicated crown fractures, crown‐root fractures, root fractures, luxation injuries, avulsion, root resorption, pulp canal obliteration and open‐apex teeth. Emphasis is placed on the treatment of traumatized immature teeth where maintenance of pulp blood supply is important to encourage continued development of the root system. Only the treatment of traumatized permanent anterior teeth is reviewed.

Information contained in this article is based on a review of the literature on dental trauma which involved a MEDLINE search using the key words “dental trauma” and the individual topics listed above. The guidelines produced by the International Association of Dental Traumatology, the American Academy of Pediatric Dentistry and the American Association of Endodontists were also reviewed and the recommendations contained in this paper are in concert with the major recommendations of these bodies.
An overview of the dental pulp: its functions and responses to injury
Authors: Yu C. , Abbott PV
Published: March 2008

The dental pulp is a unique tissue and its importance in the long‐term prognosis of the tooth is often ignored by clinicians. It is unique in that it resides in a rigid chamber which provides strong mechanical support and protection from the microbial rich oral environment. If this rigid shell loses its structural integrity, the pulp is under the threat of the adverse stimuli from the mouth, such as caries, cracks, fractures and open restoration margins, all of which provide pathways for micro‐organisms and their toxins to enter the pulp. The pulp initially responds to irritation by becoming inflamed and, if left untreated, this will progress to pulp necrosis and infection. The inflammation will also spread to the surrounding alveolar bone and cause periapical pathosis. The magnitude of pulp‐related problems should not be underestimated since their most serious consequence is oral sepsis, which can be life threatening, and hence correct diagnosis and management are essential. Clinicians must have a thorough understanding of the physiological and pathological features of the dental pulp as well as the biological consequences of treatment interventions.
The principles of techniques for cleaning root canals
Authors: Young GR , Parashos P. , Messer HH
Published: March 2008

Chemomechanical preparation of the root canal includes both mechanical instrumentation and antibacterial irrigation, and is principally directed toward the elimination of micro‐organisms from the root canal system. A variety of instruments and techniques have been developed and described for this critical stage of root canal treatment. Since their introduction in 1988, nickel‐titanium (NiTi) rotary instruments have become a mainstay in clinical endodontics because of their exceptional ability to shape root canals with potentially fewer procedural complications. Safe clinical usage of NiTi instruments requires an understanding of basic metallurgy of the alloy including fracture mechanisms and their correlation to canal anatomy. This paper reviews the biologic principles of preparing root canals with an emphasis on correct use of current rotary NiTi instrumentation techniques and systems. The role and properties of contemporary root canal irrigants is also discussed.
Characterization of a functional (pro)renin receptor in rat brain neurons
Authors: Shan Zhiying , Cuadra Adolfo E. , Sumners Colin , Raizada Mohan K.
Published: March 2008

(Pro)renin receptor (PRR), the newest member of the renin–angiotensin system (RAS), is turning out to be an important player in the regulation of the cardiovascular system. It plays a pivotal role in activation of the local RAS and stimulates signalling pathways involved in proliferative and hypertrophic mechanisms. However, the role of PRR in the brain remains unknown. Thus, our objective in this study was to determine whether a functional PRR is present in neurons within the brain. Neuronal co‐cultures from the hypothalamus and brainstem areas of neonatal rat brain express PRR mRNA. Immunoreactivity for PRR was primarily localized on the neuronal cell soma and in discrete areas in the neurites. Treatment of neurons with renin, in the presence of 2 μmlosartan, caused a time‐ and dose‐dependent stimulation of phosphorylation of extracellular signal related kinase ERK1 (p44) and ERK2 (p42) isoforms of mitogen‐activated protein kinase. Optimal stimulation of fourfold was observed within 2 min with 20 nmrenin. Electrophysiological recordings showed that treatment of the neurons with renin, in the presence of 2 μmlosartan, resulted in a steady and stable decrease in action potential frequency. A 46% decrease in action potential frequency was observed within 5 min of treatment and was attenuated by co‐incubation with a PRR blocking peptide. These observations demonstrate that the PRR is present in neurons within the brain and that its activation by renin initiates the MAP kinase signalling pathway and inhibition of neuronal activity.
Unsteady Vortex Flows Produced by Trailing Edge Articulation
Authors: Huyer Stephen A. , Beal David , Macumber Daniel , Annaswamy Anuradha
Published: March 2008

The unsteady vortex flows produced by biologically inspired tail articulation are investigated. The application is to provide active means of reducing tonal noise due to upstream wake interaction with downstream propellers on underwater vehicles. By reducing the wake velocity defect, the periodic unsteady propeller blade pressure fluctuations that are the source of the noise should be reduced. Accordingly, experiments to measure the flows produced by an upstream stator fitted with a movable trailing edge were carried out in a water tunnel for Reynolds numbers in the range 75,000<Re<300,000. A stator model with a hinged flapping trailing edge section operated at frequencies up to 21Hz corresponding to a range of Strouhal number 0.0<St<0.18. Velocity measurements of the articulating stator wake were carried out by laser Doppler velocimetry (LDV) and particle image velocimetry (PIV). Reduced mean and rms LDV data show that trailing edge articulation generates vortex structures with dependence on both Strouhal number and articulation amplitude. Estimates of the time mean stator drag that were obtained by integrating the mean wake profiles were used to estimate optimal Strouhal numbers in terms of wake elimination. Instantaneous phase-averaged measurements via PIV show a transition in the unsteady stator wake flow regimes as St is increased, from a deflected vortex sheet to a series of rolled up, discrete vortices. Measurements of the wake highlight the characteristics of the vortex structures and provide a means to estimate the impact on downstream propellers.
Selenate-Dependent Anaerobic Arsenite Oxidation by a Bacterium from Mono Lake, California
Authors: Fisher Jenny C. , Hollibaugh James T.
Published: March 2008

Arsenate was produced when anoxic Mono Lake water samples were amended with arsenite and either selenate or nitrate. Arsenite oxidation did not occur in killed control samples or live samples with no added terminal electron acceptor. Potential rates of anaerobic arsenite oxidation with selenate were comparable to those with nitrate (∼12 to 15 μmol·liter
−1
h
−1
). A pure culture capable of selenate-dependent anaerobic arsenite oxidation (strain ML-SRAO) was isolated from Mono Lake water into a defined salts medium with selenate, arsenite, and yeast extract. This strain does not grow chemoautotrophically, but it catalyzes the oxidation of arsenite during growth on an organic carbon source with selenate. No arsenate was produced in pure cultures amended with arsenite and nitrate or oxygen, indicating that the process is selenate dependent. Experiments with washed cells in mineral medium demonstrated that the oxidation of arsenite is tightly coupled to the reduction of selenate. Strain ML-SRAO grows optimally on lactate with selenate or arsenate as the electron acceptor. The amino acid sequences deduced from the respiratory arsenate reductase gene (
arrA
) from strain ML-SRAO are highly similar (89 to 94%) to those from two previously isolated Mono Lake arsenate reducers. The 16S rRNA gene sequence of strain ML-SRAO places it within the
Bacillus
RNA group 6 of gram-positive bacteria having low G+C content.
Mechanism for Oxidation of High-Molecular-Weight Substrates by a Fungal Versatile Peroxidase, MnP2
Authors: Tsukihara Takahisa , Honda Yoichi , Sakai Ryota , Watanabe Takahito , Watanabe Takashi
Published: March 2008

Unlike general peroxidases,Pleurotus ostreatusMnP2 was reported to have a unique property of direct oxidization of high-molecular-weight compounds, such as Poly R-478 and RNase A. To elucidate the mechanism for oxidation of polymeric substrates by MnP2, a series of mutant enzymes were produced by using a homologous gene expression system, and their reactivities were characterized. A mutant enzyme with an Ala substituting for an exposing Trp (W170A) drastically lost oxidation activity for veratryl alcohol (VA), Poly R-478, and RNase A, whereas the kinetic properties for Mn2+and H2O2were substantially unchanged. These results demonstrated that, in addition to VA, the high-molecular-weight substrates are directly oxidized by MnP2 at W170. Moreover, in the mutants Q266F and V166/168L, amino acid substitution(s) around W170 resulted in a decreased activity only for the high-molecular-weight substrates. These results, along with the three-dimensional modeling of the mutants, suggested that the mutations caused a steric hindrance to access of the polymeric substrates to W170. Another mutant, R263N, contained a newly generated N glycosylation site and showed a higher molecular mass in sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis. Interestingly, the R263N mutant exhibited an increased reactivity with VA and high-molecular-weight substrates. The existence of an additional carbohydrate modification and the catalytic properties in this mutant are discussed. This is the first study of a direct mechanism for oxidation of high-molecular-weight substrates by a fungal peroxidase using a homologous gene expression system.
Taxonomic and Strain-Specific Identification of the Probiotic Strain
Lactobacillus rhamnosus
35 within the
Lactobacillus casei
Group
Authors: Coudeyras Sophie , Marchandin Hélène , Fajon Céline , Forestier Christiane
Published: March 2008

Lactobacilli are lactic acid bacteria that are widespread in the environment, including the human diet and gastrointestinal tract. Some
Lactobacillus
strains are regarded as probiotics because they exhibit beneficial health effects on their host. In this study, the long-used probiotic strain
Lactobacillus rhamnosus
35 was characterized at a molecular level and compared with seven reference strains from the
Lactobacillus casei
group. Analysis of
rrn
operon sequences confirmed that
L. rhamnosus
35 indeed belongs to the
L. rhamnosus
species, and both temporal temperature gradient gel electrophoresis and ribotyping showed that it is closer to the probiotic strain
L. rhamnosus
ATCC 53103 (also known as
L. rhamnosus
GG) than to the species type strain. In addition,
L. casei
ATCC 334 gathered in a coherent cluster with
L. paracasei
type strains, unlike
L. casei
ATCC 393, which was closer to
L. zeae
; this is evidence of the lack of relatedness between the two
L. casei
strains. Further characterization of the eight strains by pulsed-field gel electrophoresis repetitive DNA element-based PCR identified distinct patterns for each strain, whereas two isolates of
L. rhamnosus
35 sampled 40 years apart could not be distinguished. By subtractive hybridization using the
L. rhamnosus
GG genome as a driver, we were able to isolate five
L. rhamnosus
35-specific sequences, including two phage-related ones. The primer pairs designed to amplify these five regions allowed us to develop rapid and highly specific PCR-based identification methods for the probiotic strain
L. rhamnosus
35.
Development of a Microbial Time/Temperature Indicator Prototype for Monitoring the Microbiological Quality of Chilled Foods
Authors: Vaikousi Hariklia , Biliaderis Costas G. , Koutsoumanis Konstantinos P.
Published: March 2008

A time/temperature indicator (TTI) system based on the growth and metabolic activity of a
Lactobacillus sakei
strain was developed for monitoring food quality throughout the chilled-food chain. In the designed system, an irreversible color change of a chemical chromatic indicator (from red to yellow) progressively occurs due to the pH decline that results from microbial growth and metabolism in a selected medium. The relation of the TTI response (color change) to the growth and metabolic activity (glucose consumption, lactic acid production, pH decrease) of
L. sakei
was studied. In addition, the temperature dependence of the TTI kinetics was investigated isothermally in the range of 0 to 16°C and modeled with a system of differential equations. At all temperatures tested, the pH and color changes of the TTI system followed closely the growth of
L. sakei
, with the endpoint (the time at which a distinct visual color change to the final yellow was observed) of the TTI coinciding with a population level of 10
7
to 10
8
CFU/ml. The endpoint decreased from 27 days at 0°C to 2.5 days at 16°C, yielding an activation energy of 97.7 kJ/mol, which was very close to the activation energy of the
L. sakei
growth rate in the TTI substrate (103.2 kJ/mol). Furthermore, experiments conducted on the effect of the inoculum level showed a negative linear relationship between the level of
L. sakei
inoculated in the system medium and the endpoint of the TTI. For example, the endpoint at 8°C ranged from 6 to 2 days for inoculum levels of 10
1
and 10
6
CFU/ml, respectively. This relationship allows the easy adjustment of the TTI endpoint at a certain temperature according to the shelf life of the food product of concern by using an appropriate inoculum level of
L. sakei
. The microbial TTI prototype developed in the present study could be used as an effective tool for monitoring shelf life during the distribution and storage of food products that are spoiled primarily by lactic acid bacteria or other bacteria exhibiting similar kinetic responses and spoilage potentials. Apart from the low cost, the main advantage of the proposed TTI is that its response closely matches the loss of the quality of a food product by simulating the microbial spoilage process in particular environments.
The Type III Secretion System of
Xanthomonas fuscans
subsp.
fuscans
Is Involved in the Phyllosphere Colonization Process and in Transmission to Seeds of Susceptible Beans
Authors: Darsonval A. , Darrasse A. , Meyer D. , Demarty M. , Durand K. , Bureau C. , Manceau C. , Jacques M.-A.
Published: March 2008

Understanding the survival, multiplication, and transmission to seeds of plant pathogenic bacteria is central to study their pathogenesis. We hypothesized that the type III secretion system (T3SS), encoded by
hrp
genes, could have a role in host colonization by plant pathogenic bacteria. The seed-borne pathogen
Xanthomonas fuscans
subsp.
fuscans
causes common bacterial blight of bean (
Phaseolus vulgaris
). Directed mutagenesis in strain CFBP4834-R of
X. fuscans
subsp.
fuscans
and bacterial population density monitoring on bean leaves showed that strains with mutations in the
hrp
regulatory genes,
hrpG
and
hrpX
, were impaired in their phyllospheric growth, as in the null interaction with
Escherichia coli
C600 and bean. In the compatible interaction, CFBP4834-R reached high phyllospheric population densities and was transmitted to seeds at high frequencies with high densities. Strains with mutations in structural
hrp
genes maintained the same constant epiphytic population densities (1 × 10
5
CFU g
−1
of fresh weight) as in the incompatible interaction with
Xanthomonas campestris
pv. campestris ATCC 33913 and the bean. Low frequencies of transmission to seeds and low bacterial concentrations were recorded for CFBP4834-R
hrp
mutants and for ATCC 33913, whereas
E. coli
C600 was not transmitted. Moreover, unlike the wild-type strain, strains with mutations in
hrp
genes were not transmitted to seeds by vascular pathway. Transmission to seeds by floral structures remained possible for both. This study revealed the involvement of the
X. fuscans
subsp.
fuscans
T3SS in phyllospheric multiplication and systemic colonization of bean, leading to transmission to seeds. Our findings suggest a major contribution of
hrp
regulatory genes in host colonization processes.
IS
6110
, a
Mycobacterium tuberculosis
Complex-Specific Insertion Sequence, Is Also Present in the Genome of
Mycobacterium smegmatis
, Suggestive of Lateral Gene Transfer among Mycobacterial Species
Authors: Coros Abbie , DeConno Erin , Derbyshire Keith M.
Published: March 2008

IS
6110
is an insertion element found exclusively within the members of the
Mycobacterium tuberculosis
complex (MTBC), and because of this exclusivity, it has become an important diagnostic tool in the identification of MTBC species. The restriction of IS
6110
to the MTBC is hypothesized to arise from the inability of these bacteria to exchange DNA. We have identified an IS
6110
-related element in a strain of
Mycobacterium smegmatis.
The presence of IS
6110
indicates that lateral gene transfer has occurred among mycobacterial species, suggesting that the mycobacterial gene pool is larger than previously suspected.
Influence of the σBStress Factor andyxaB, the Gene for a Putative Exopolysaccharide Synthase under σBControl, on Biofilm Formation
Authors: Nagórska Krzysztofa , Hinc Krzysztof , Strauch Mark A. , Obuchowski Michał
Published: March 2008

Bacillus subtilisforms structured communities of biofilms encased in an exopolysaccharide matrix on solid surfaces and at the air-liquid interface. It is postulated that nonoptimal growth conditions induce this multicellular behavior. We showed that under laboratory conditions a strain deleted forsigBwas unable to form a floating pellicle on the surface of a liquid medium. However, overexpression ofyxaB, encoding a putative exopolysaccharide synthase, from a pSpacpromoter in asigB-deleted strain resulted in partial recovery of the wild-type phenotype, indicating the participation of the YxaB protein in this multicellular process. We present data concerning the regulation of transcription of genesyxaBandyxaA, encoding a putative glycerate kinase. Both genes are cotranscribed as a single transcription unit from a σA-dependent promoter during vegetative growth of a liquid bacterial culture. The promoter driving transcription of theyxaABoperon is regulated by AbrB. In addition, the second gene in the operon,yxaB, possesses its own promoter, which is recognized by RNA polymerase containing the σBsubunit. This transcription start site is used under general stress conditions, resulting in increased expression.
ATP-Induced Shrinkage of DNA with MukB Protein and the MukBEF Complex of
Escherichia coli
Authors: Chen Ning , Zinchenko Anatoly A. , Yoshikawa Yuko , Araki Sumiko , Adachi Shun , Yamazoe Mitsuyoshi , Hiraga Sota , Yoshikawa Kenichi
Published: March 2008

Fluorescence microscopic observation of individual T4 DNA molecules revealed that the MukBEF complex (bacterial condensin) and its subunit, the MukB (a member of the SMC [structural maintenance of chromosomes] superfamily) homodimer, of
Escherichia coli
markedly shrunk large DNA molecules in the presence of hydrolyzable ATP. In contrast, in the presence of ADP or ATP-γS, the conformation of DNA was almost not changed. This suggests that the ATPase activity of subunit MukB is essential for shrinking large DNA molecules. Stretching experiments on the shrunken DNA molecules in the presence of ATP and MukBEF indicated a cross-bridging interaction between DNA molecules.
Centrifugal modelling of nonsorbing, nonequilibrium solute transport in a locally inhomogeneous soil
Authors: Li L. , Barry D.A. , Stone K.J.L.
Published: March 2008

This paper presents results of centrifugal modelling of physical nonequilibrium transport of nonsorbing solute in a locally inhomogeneous soil. Mathematical modelling of this class of transport process is restricted by the difficulties in determining the model parameters. The modelling results suggest that physical modelling on a geotechnical centrifuge may offer another approach to tackle this problem under certain conditions. Key words : tracer transport, centrifuge, physical modelling, heterogeneous soil, two-region model, scaling.
Tension tests on bored piles in cemented desert sands
Authors: Ismael Nabil F. , Al-Sanad Hasan A. , Al-Otaibi Fahad
Published: March 2008

The load transfer of bored piles in medium dense cemented sands was examined by field tests at two sites. At the first site, two bored piles were tested in axial tension to failure. One pile was instrumented with strain guages to measure the axial load distribution at all load increments. The results indicate significant load transfer along the pile length. The average shaft resistance measured was 80 and 100 kN/m2 in medium-dense and very dense, weakly cemented calcareous sand, respectively. At the second site, a tension test was carried out on a bored pile in uncemented cohesionless sand. By comparing the results at the two sites the influence of cementation on the uplift capacity was assessed. The shaft resistance depends on many factors including the relative density, degree of cementation, soil fabric, and method of construction. It increases with the standard penetration test (SPT) N values; however, the SPT is not considered a reliable test for strength characterization of cemented sands. Analysis of the pile capacity can be made considering both components of soil strength, namely, cohesion intercept c and angle of shearing resistance [Formula: see text]. Key words : bored piles, cemented sands, uplift capacity, friction, shaft resistance.
Inclusion of specific water volume within an elasto-plastic model for unsaturated soil
Authors: Wheeler S J
Published: March 2008

Existing elasto-plastic critical state constitutive models for unsaturated soil provide no information on the variation of water content or degree of saturation. These models cannot therefore, for example, be used to predict unsaturated soil behaviour during undrained loading, when the variation of suction is determined by the requirement that water content remains constant. This problem has been tackled by extending an existing elasto-plastic model to include relationships describing the variation of specific water volume (the volume of water and solids in an element of soil containing unit volume of solids). The proposed form of the variation of specific water volume was based on consideration of the soil fabric, resulting in a coupled form of elasto-plastic behaviour. Predictions from the elasto-plastic model showed good agreement with the experimental results from suction-controlled triaxial tests on unsaturated samples of compacted speswhite kaolin. Normal compression lines for specific water volume at different values of suction were well predicted, as was the variation of specific water volume during wetting. Critical state values of specific water volume were slightly underestimated, but test paths for both drained and undrained shearing were predicted with reasonable success.

Key words: compacted clays, constitutive model, critical state, elasto-plasticity, triaxial tests, unsaturated.
In situ soil flushing using prefabricated vertical drains
Authors: Gabr M A , Bowders J J , Wang J , Quaranta J
Published: March 2008

The use of prefabricated vertical drains (PVDs) for enhanced soil flushing was investigated using a bench scale experimental setup. Soil samples were prepared and saturated in contaminant recovery cells (CRC). The PVDs were installed in rectangular and circular configurations, and a vacuum was applied to recover subsurface water. A predictive model for contaminant transport using the PVD-enhanced soil flushing was developed and presented. Results from the CRC tests using four PVDs in a rectangular arrangement indicated that the volume of the retrieved fluid increased as a function of the vacuum level and was approximately 0.55 mL/s at a vacuum level of 9.0 kPa. This represented a recovery efficiency of approximately 100%, since the base inflow through the sample was 0.55 mL/s. Using six PVDs in a circular configuration with a spacing of 14 mm from the center of the circle, a flow rate of approximately 6 mL/s was recovered under 6.8 kPa of vacuum. The average drawdown under a vacuum of 8.6 kPa ranged from 15 to 45 mm, and the zone of effective drawdown was measured to be approximately 200 mm in diameter. This value is approximately 10 times the effective diameter of the PVDs. An injectionextraction test indicated that, under an applied injection pressure of 3.5 kPa, an injection flow rate of approximately 6.5 mL/s was measured. At a vacuum pressure of 6 kPa and using the cicular configuration, the injection and recovery flow rates were approximately balanced. Such balance is essential to avoid decreasing the flushing rate due to the compression of the soil voids as well as to avoid the desaturation of soil profile.

Key words: contaminant transport, injection, model, prefabricated vertical drains, retardation, soil flushing, vacuum.
Application of pipe temperature simulator for Norman Wells oil pipeline
Authors: Nixon JF (Derick) , MacInnes Kaye L
Published: March 2008

The Norman Wells oil pipeline has been operating successfully for 10 years, transporting crude oil from the Norman Wells field in the Northwest Territories to southern markets. The temparatures of the oil in the pipeline have been closely monitored at several locations, and a detailed record of the thermal performance of the pipeline and the response of the surrounding permafrost soils is available. Recently, a geothermal program has been developed to predict the temparature profiles along a buried pipeline in more detail than has hitherto been attempted. The recently developed simulator accounts for freezing and thawing around the pipeline, while accounting for the heat losses from the pipeline to the ground as the contents flow through the line. The Norman Wells oil pipeline has provided an opportunity to test and calibrate the new model. Comparaisons between observed temperatures along the line and predictions from the simulator have been made, and the agreement is generally extremely good. The downstream effects of recent changes to the operating temperatures at Norman Wells were accurately predicted, illustrating the potential applications of model. The simulator will allow the effects of future planned changes in operating conditions to be more accurately evaluated, as well as playing an important part in design engineering studies for future oil, water, and gas pipeline projects elsewhere.

Key words: pipeline, geothermal, oil temperatures. permafrost, thaw, Norman Wells.
Microstructure of a compacted silt
Authors: Delage Pierre , Audiguier Martine , Cui Yu-Jun , Howat Michael D
Published: March 2008

This paper presents a qualitative and quantitative study of the microstructure of a compacted silt, carried out using a scanning electron microscope and mercury intrusion pore size distribution measurements. Samples have been statically compacted at three water contents: on the dry side of the standard Proctor optimum water content, at the optimum, and on the wet side. The wet sample has a matrix type structure, with a clayey fraction filling the voids and adhering to the silt-sized grains, whereas the other samples display a structure characterized by a skeleton made of silt grain aggregates linked together by clayey bidges. The distribution of water and air within the microstructure of the compacted soil is described for each of the three compaction states.

Key words: compacted soil, microstructure, scanning electron microscope, pore size distribution, mercury intrusion, clay hydration.
LATE-TIME TAIL OF A COUPLED SCALAR FIELD IN THE BACKGROUND OF A BLACK HOLE WITH A GLOBAL MONOPOLE
Authors: CHEN SONGBAI , JING JILIANG
Published: March 2008

Using the technique of spectral decomposition, we investigated the late-time tails of massless and massive coupled scalar fields in the background of a black hole with a global monopole. We found that due to the existence of the coupling between the scalar and gravitational fields, the massless scalar field decay faster at timelike infinity i+, and so does the massive one in the intermediate late time. But the asymptotically late-time tail for the massive scalar field is not affected and its decay rate is still t-5/6.
PROPER CURVATURE COLLINEATIONS IN NONSTATIC SPHERICALLY SYMMETRIC SPACE–TIMES
Authors: SHABBIR GHULAM , RAMZAN M.
Published: March 2008

A study of nonstatic spherically symmetric space–times according to their proper curvature collineations is given by using the rank of the 6×6 Riemann matrix and direct integration techniques. Studying proper curvature collineations in each case of the above space–times it is shown that when the above space–times admit proper curvature collineations, they turn out to be static spherically symmetric and form an infinite dimensional vector space. In the nonstatic cases curvature collineations are just Killing vector fields.
RADIATIVE PROPERTIES OF THE STUECKELBERG MECHANISM
Authors: MARSHALL T. J. , MCKEON D. G. C.
Published: March 2008

We examine the mechanism for generating a mass for a U(1) vector field introduced by Stueckelberg. First, it is shown that renormalization of the vector mass is identical to the renormalization of the vector field on account of gauge invariance. We then consider how the vector mass affects the effective potential in scalar quantum electrodynamics at one-loop order. The possibility of extending this mechanism to couple, in a gauge invariant way, a charged vector field to the photon is discussed.