Cancer-associated fibroblasts produce matrix-bound vesicles that influence endothelial cell function

Intercellular communication between different cell types in solid tumors contributes to tumor growth and metastatic dissemination. The secretome of cancer-associated fibroblasts (CAFs) plays major roles in these processes. Using human mammary CAFs, we showed that CAFs with a myofibroblast phenotype released extracellular vesicles that transferred proteins to endothelial cells (ECs) that affected their interaction with immune cells. Mass spectrometry-based proteomics identified proteins transferred from CAFs to ECs, which included plasma membrane receptors. Using THY1 as an example of a transferred plasma membrane-bound protein, we showed that CAF-derived proteins increased the adhesion of a monocyte cell line to ECs. CAFs produced high amounts of matrix-bound EVs, which were the primary vehicles of protein transfer. Hence, our work paves the way for future studies that investigate how CAF-derived matrix-bound EVs influence tumor pathology by regulating the function of neighboring cancer, stromal, and immune cells.

Engineering Escherichia coli for increased Und-P availability leads to material improvements in glycan expression technology

BACKGROUND

Bacterial surface glycans are assembled by glycosyltransferases (GTs) that transfer sugar monomers to long-chained lipid carriers. Most bacteria employ the 55-carbon chain undecaprenyl phosphate (Und-P) to scaffold glycan assembly. The amount of Und-P available for glycan synthesis is thought to be limited by the rate of Und-P synthesis and by competition for Und-P between phosphoglycosyl transferases (PGTs) and GTs that prime glycan assembly (which we collectively refer to as PGT/GTs). While decreasing Und-P availability disrupts glycan synthesis and promotes cell death, less is known about the effects of increased Und-P availability.

RESULTS

To determine if cells can maintain higher Und-P levels, we first reduced intracellular competition for Und-P by deleting all known non-essential PGT/GTs in the Gram-negative bacterium Escherichia coli (hereafter called ΔPGT/GT cells). We then increased the rate of Und-P synthesis in ΔPGT/GT cells by overexpressing the Und-P(P) synthase uppS from a plasmid (puppS). Und-P quantitation revealed that ΔPGT/GT/puppS cells can be induced to maintain 3-fold more Und-P than wild type cells. Next, we determined how increasing Und-P availability affects glycan expression. Interestingly, increasing Und-P availability increased endogenous and recombinant glycan expression. In particular, ΔPGT/GT/puppS cells could be induced to express 7-fold more capsule from Streptococcus pneumoniae serotype 4 than traditional E. coli cells used to express recombinant glycans.

CONCLUSIONS

We demonstrate that the biotechnology standard bacterium E. coli can be engineered to maintain higher levels of Und-P. The results also strongly suggest that Und-P pathways can be engineered to increase the expression of potentially any Und-P-dependent polymer. Given that many bacterial glycans are central to the production of vaccines, diagnostics, and therapeutics, increasing Und-P availability should be a foremost consideration when designing bacterial glycan expression systems.

Proline metabolism shapes the tumor microenvironment: from collagen deposition to immune evasion

Proline is a nonessential amino acid, and its metabolism has been implicated in numerous malignancies. Together with a direct role in regulating cancer cells' proliferation and survival, proline metabolism plays active roles in shaping the tumor microenvironment (TME). Cancer-associated fibroblasts (CAFs) display high rates of proline biosynthesis to support the production of collagen for the extracellular matrix (ECM). Indeed, impaired proline metabolism in CAFs results in reduced collagen deposition and compromises the growth and metastatic spread of cancer. Moreover, the rate of proline metabolism regulates intracellular reactive oxygen species (ROS) levels, which influence the production and release of cytokines from cancer cells, contributing toward an immune-permissive TME. Hence, targeting proline metabolism is a promising anticancer strategy that could improve patients' outcome and response to immunotherapy.

Omentum-derived matrix enables the study of metastatic ovarian cancer and stromal cell functions in a physiologically relevant environment

High-grade serous (HGS) ovarian cancer is the most lethal gynaecological disease in the world and metastases is a major cause. The omentum is the preferential metastatic site in HGS ovarian cancer patients and in vitro models that recapitulate the original environment of this organ at cellular and molecular level are being developed to study basic mechanisms that underpin this disease. The tumour extracellular matrix (ECM) plays active roles in HGS ovarian cancer pathology and response to therapy. However, most of the current in vitro models use matrices of animal origin and that do not recapitulate the complexity of the tumour ECM in patients. Here, we have developed omentum gel (OmGel), a matrix made from tumour-associated omental tissue of HGS ovarian cancer patients that has unprecedented similarity to the ECM of HGS omental tumours and is simple to prepare. When used in 2D and 3D in vitro assays to assess cancer cell functions relevant to metastatic ovarian cancer, OmGel performs as well as or better than the widely use Matrigel and does not induce additional phenotypic changes to ovarian cancer cells. Surprisingly, OmGel promotes pronounced morphological changes in cancer associated fibroblasts (CAFs). These changes were associated with the upregulation of proteins that define subsets of CAFs in tumour patient samples, highlighting the importance of using clinically and physiologically relevant matrices for in vitro studies. Hence, OmGel provides a step forward to study the biology of HGS omental metastasis. Metastasis in the omentum are also typical of other cancer types, particularly gastric cancer, implying the relevance of OmGel to study the biology of other highly lethal cancers.

Development of a novel glycoengineering platform for the rapid production of conjugate vaccines

Conjugate vaccines produced either by chemical or biologically conjugation have been demonstrated to be safe and efficacious in protection against several deadly bacterial diseases. However, conjugate vaccine assembly and production have several shortcomings which hinders their wider availability. Here, we developed a tool, Mobile-element Assisted Glycoconjugation by Insertion on Chromosome, MAGIC, a novel biotechnological platform that overcomes the limitations of the current conjugate vaccine design method(s). As a model, we focused our design on a leading bioconjugation method using N-oligosaccharyltransferase (OTase), PglB. The installation of MAGIC led to at least twofold increase in glycoconjugate yield via MAGIC when compared to conventional N-OTase based bioconjugation method(s). Then, we improved MAGIC to (a) allow rapid installation of glycoengineering component(s), (b) omit the usage of antibiotics, (c) reduce the dependence on protein induction agents. Furthermore, we show the modularity of the MAGIC platform in performing glycoengineering in bacterial species that are less genetically tractable than the commonly used Escherichia coli. The MAGIC system promises a rapid, robust and versatile method to develop vaccines against serious bacterial pathogens. We anticipate the utility of the MAGIC platform could enhance vaccines production due to its compatibility with virtually any bioconjugation method, thus expanding vaccine biopreparedness toolbox.

Bicarbonate transport as regulator of antitumour immunity in pancreatic cancer

Bicarbonate transport is a pre-existing mechanism of pH regulation in pancreatic ductal cells. In a recent study, Cappellesso et al. demonstrated that pancreatic ductal adenocarcinoma metabolic rewiring creates an acidic environment, enhanced by bicarbonate import into cancer cells via SLC4A4. This acidity favours protumourigenic immunosuppression. Targeting SLC4A4 neutralises environmental pH and restores antitumour immunity, sensitising tumours to immune checkpoint blockade.

Cancer-associated fibroblasts require proline synthesis by PYCR1 for the deposition of pro-tumorigenic extracellular matrix

Elevated production of collagen-rich extracellular matrix is a hallmark of cancer-associated fibroblasts (CAFs) and a central driver of cancer aggressiveness. Here we find that proline, a highly abundant amino acid in collagen proteins, is newly synthesized from glutamine in CAFs to make tumour collagen in breast cancer xenografts. PYCR1 is a key enzyme for proline synthesis and highly expressed in the stroma of breast cancer patients and in CAFs. Reducing PYCR1 levels in CAFs is sufficient to reduce tumour collagen production, tumour growth and metastatic spread in vivo and cancer cell proliferation in vitro. Both collagen and glutamine-derived proline synthesis in CAFs are epigenetically upregulated by increased pyruvate dehydrogenase-derived acetyl-CoA levels. PYCR1 is a cancer cell vulnerability and potential target for therapy; therefore, our work provides evidence that targeting PYCR1 may have the additional benefit of halting the production of a pro-tumorigenic extracellular matrix. Our work unveils new roles for CAF metabolism to support pro-tumorigenic collagen production.

Engineering a suite of E. coli strains for enhanced expression of bacterial polysaccharides and glycoconjugate vaccines

BACKGROUND

Glycoengineering, in the biotechnology workhorse bacterium, Escherichia coli, is a rapidly evolving field, particularly for the production of glycoconjugate vaccine candidates (bioconjugation). Efficient production of glycoconjugates requires the coordinated expression within the bacterial cell of three components: a carrier protein, a glycan antigen and a coupling enzyme, in a timely fashion. Thus, the choice of a suitable E. coli host cell is of paramount importance. Microbial chassis engineering has long been used to improve yields of chemicals and biopolymers, but its application to vaccine production is sparse.

RESULTS

In this study we have engineered a family of 11 E. coli strains by the removal and/or addition of components rationally selected for enhanced expression of Streptococcus pneumoniae capsular polysaccharides with the scope of increasing yield of pneumococcal conjugate vaccines. Importantly, all strains express a detoxified version of endotoxin, a concerning contaminant of therapeutics produced in bacterial cells. The genomic background of each strain was altered using CRISPR in an iterative fashion to generate strains without antibiotic markers or scar sequences.

CONCLUSIONS

Amongst the 11 modified strains generated in this study, E. coli Falcon, Peregrine and Sparrowhawk all showed increased production of S. pneumoniae serotype 4 capsule. Eagle (a strain without enterobacterial common antigen, containing a GalNAc epimerase and PglB expressed from the chromosome) and Sparrowhawk (a strain without enterobacterial common antigen, O-antigen ligase and chain length determinant, containing a GalNAc epimerase and chain length regulators from Streptococcus pneumoniae) respectively produced an AcrA-SP4 conjugate with 4 × and 14 × more glycan than that produced in the base strain, W3110. Beyond their application to the production of pneumococcal vaccine candidates, the bank of 11 new strains will be an invaluable resource for the glycoengineering community.

Production of Vaccines Using Biological Conjugation

The production of conjugate vaccines within an E. coli (Escherichia coli) host provides an inexhaustible supply without the need for culture of pathogenic organisms. The machinery for expression of glycan and acceptor protein, as well as the coupling enzyme, are all housed within the E. coli chassis, meaning that there are no additional steps required for individual purification and chemical conjugation of components. In addition, there are far fewer purification steps necessary to obtain a purified glycoconjugate for use in vaccine testing. Here we describe production and purification of a HIS-tagged Campylobacter jejuni AcrA protein conjugated to Streptococcus pneumoniae serotype 4 capsule.

Two opposing sub-populations of fibroblasts decide progression of pancreatic cancer

Fibroblasts are a major non-neoplastic component of solid tumors, yet it is unclear whether they promote or oppose cancer. In this issue of Cancer Cell, Hutton et al. report two distinct fibroblast subpopulations that are defined by a single marker, one subpopulation that is tumor permissive and the other that is tumor suppressive and supports anti-tumor immunity.

Regulation of Extracellular Matrix Production in Activated Fibroblasts: Roles of Amino Acid Metabolism in Collagen Synthesis

Cancer associated fibroblasts (CAFs) are a major component of the tumour microenvironment in most tumours, and are key mediators of the response to tissue damage caused by tumour growth and invasion, contributing to the observation that tumours behave as 'wounds that do not heal'. CAFs have been shown to play a supporting role in all stages of tumour progression, and this is dependent on the highly secretory phenotype CAFs develop upon activation, of which extracellular matrix (ECM) production is a key element. A collagen rich, stromal ECM has been shown to influence tumour growth and metastasis, exclude immune cells and impede drug delivery, and is associated with poor prognosis in many cancers. CAFs also extensively remodel their metabolism to support cancer cells, however, it is becoming clear that metabolic rewiring also supports intrinsic functions of activated fibroblasts, such as increased ECM production. In this review, we summarise how fibroblasts metabolically regulate ECM production, focussing on collagen production, at the transcriptional, translational and post-translational level, and discuss how this can provide possible strategies for effectively targeting CAF activation and formation of a tumour-promoting stroma.

Development of an automated platform for the optimal production of glycoconjugate vaccines expressed in Escherichia coli

Protein Glycan Coupling Technology (PGCT) uses purposely modified bacterial cells to produce recombinant glycoconjugate vaccines. This vaccine platform holds great potential in this context, namely due to its modular nature, the simplified production process in comparison to traditional chemical conjugation methods, and its amenability to scaled-up operations. As a result, a considerable reduction in production time and cost is expected, making PGCT-made vaccines a suitable vaccine technology for low-middle income countries, where vaccine coverage remains predominantly low and inconsistent. This work aims to develop an integrated whole-process automated platform for the screening of PGCT-made glycoconjugate vaccine candidates. The successful translation of a bench scale process for glycoconjugate production to a microscale automated setting was achieved. This was integrated with a numerical computational software that allowed hands-free operation and a platform adaptable to biological variation over the course of a production process. Platform robustness was proven with both technical and biological replicates and subsequently the platform was used to screen for the most favourable conditions for production of a pneumococcal serotype 4 vaccine candidate. This work establishes an effective automated platform that enabled the identification of the most suitable E. coli strain and genetic constructs to be used in ongoing early phase research and be further brought into preclinical trials.

Accessing unexplored regions of sequence space in directed enzyme evolution via insertion/deletion mutagenesis

Insertions and deletions (InDels) are frequently observed in natural protein evolution, yet their potential remains untapped in laboratory evolution. Here we introduce a transposon-based mutagenesis approach (TRIAD) to generate libraries of random variants with short in-frame InDels, and screen TRIAD libraries to evolve a promiscuous arylesterase activity in a phosphotriesterase. The evolution exhibits features that differ from previous point mutagenesis campaigns: while the average activity of TRIAD variants is more compromised, a larger proportion has successfully adapted for the activity. Different functional profiles emerge: (i) both strong and weak trade-off between activities are observed; (ii) trade-off is more severe (20- to 35-fold increased kcat/KM in arylesterase with 60-400-fold decreases in phosphotriesterase activity) and (iii) improvements are present in kcat rather than just in KM, suggesting adaptive solutions. These distinct features make TRIAD an alternative to widely used point mutagenesis, accessing functional innovations and traversing unexplored fitness landscape regions.

Production and efficacy of a low-cost recombinant pneumococcal protein polysaccharide conjugate vaccine

Streptococcus pneumoniae is the leading cause of bacterial pneumonia. Although this is a vaccine preventable disease, S. pneumoniae still causes over 1 million deaths per year, mainly in children under the age of five. The biggest disease burden is in the developing world, which is mainly due to unavailability of vaccines due to their high costs. Protein polysaccharide conjugate vaccines are given routinely in the developed world to children to induce a protective antibody response against S. pneumoniae. One of these vaccines is Prevnar13, which targets 13 of the 95 known capsular types. Current vaccine production requires growth of large amounts of the 13 serotypes, and isolation of the capsular polysaccharide that is then chemically coupled to a protein, such as the diphtheria toxoid CRM197, in a multistep expensive procedure. In this study, we design, purify and produce novel recombinant pneumococcal protein polysaccharide conjugate vaccines in Escherichia coli, which act as mini factories for the low-cost production of conjugate vaccines. Recombinant vaccine efficacy was tested in a murine model of pneumococcal pneumonia; ability to protect against invasive disease was compared to that of Prevnar13. This study provides the first proof of principle that protein polysaccharide conjugate vaccines produced in E. coli can be used to prevent pneumococcal infection. Vaccines produced in this manner may provide a low-cost alternative to the current vaccine production methodology.

Application of Rasch analysis in the development and psychometric evaluation of dental undergraduates preparedness assessment scale

AIMS

The aim of this study was to develop a valid and reliable scale to measure preparedness of new dental graduates.

METHODS

The scale development and validation was carried out using the Rasch measurement model. Following a pilot and pre-testing of the scale, a national study was undertaken with undergraduate students from all dental schools as well as foundation dentists in UK.

RESULTS

To examine the internal validity of the scale, we conducted a Rasch analysis. External validity of the scale was checked through validation with a range of stakeholders. An excellent fit to the Rasch model provided evidence of internal construct validity. The scale demonstrated invariance, ordered thresholds and lack of differential item functioning. Unidimensionality of the scale was confirmed by independent t-tests. The PSI value was 0.877, indicating a good degree of person separation and internal consistency. Test-retest reliability of the scale was also established.

CONCLUSIONS

The preparedness scale developed in this project reflects innovative research using a systematic approach and employment of modern psychometric methods. The scale can be used for assessment of the preparedness of undergraduate students by dental educators and potential employers as well as by the student for self-assessment.

Tumor matrix stiffness promotes metastatic cancer cell interaction with the endothelium

Tumor progression alters the composition and physical properties of the extracellular matrix. Particularly, increased matrix stiffness has profound effects on tumor growth and metastasis. While endothelial cells are key players in cancer progression, the influence of tumor stiffness on the endothelium and the impact on metastasis is unknown. Through quantitative mass spectrometry, we find that the matricellular protein CCN1/CYR61 is highly regulated by stiffness in endothelial cells. We show that stiffness-induced CCN1 activates β-catenin nuclear translocation and signaling and that this contributes to upregulate N-cadherin levels on the surface of the endothelium, in vitro This facilitates N-cadherin-dependent cancer cell-endothelium interaction. Using intravital imaging, we show that knockout of Ccn1 in endothelial cells inhibits melanoma cancer cell binding to the blood vessels, a critical step in cancer cell transit through the vasculature to metastasize. Targeting stiffness-induced changes in the vasculature, such as CCN1, is therefore a potential yet unappreciated mechanism to impair metastasis.

Recombinant expression of Streptococcus pneumoniae capsular polysaccharides in Escherichia coli

Currently, Streptococcus pneumoniae is responsible for over 14 million cases of pneumonia worldwide annually, and over 1 million deaths, the majority of them children. The major determinant for pathogenesis is a polysaccharide capsule that is variable and is used to distinguish strains based on their serotype. The capsule forms the basis of the pneumococcal polysaccharide vaccine (PPV23) that contains purified capsular polysaccharide from 23 serotypes, and the pneumococcal conjugate vaccine (PCV13), containing 13 common serotypes conjugated to CRM197 (mutant diphtheria toxin). Purified capsule from S. pneumoniae is required for pneumococcal conjugate vaccine production, and costs can be prohibitively high, limiting accessibility of the vaccine in low-income countries. In this study, we demonstrate the recombinant expression of the capsule-encoding locus from four different serotypes of S. pneumoniae within Escherichia coli. Furthermore, we attempt to identify the minimum set of genes necessary to reliably and efficiently express these capsules heterologously. These E. coli strains could be used to produce a supply of S. pneumoniae serotype-specific capsules without the need to culture pathogenic bacteria. Additionally, these strains could be applied to synthetic glycobiological applications: recombinant vaccine production using E. coli outer membrane vesicles or coupling to proteins using protein glycan coupling technology.

Is the value of oral health related to culture and environment, or function and aesthetics?

OBJECTIVE

To examine the disutility of tooth loss. It compared how people value their teeth in two countries which are culturally similar in order to explore the effect of culture on self-perceptions of oral health.

BASIC RESEARCH DESIGN

Cross sectional study.

PARTICIPANTS

Participants were recruited from subjects attending two hospitals in Turkey and in Iran.

INTERVENTIONS

Nineteen descriptions of mouths with varying degrees and types of tooth loss were presented to the participants. They were shown mouth models of partially edentate dentitions and the teeth missing were explained in relation to the participants own mouth. The participants were specifically asked to consider the role their teeth played in function (chewing), communication (speech) and aesthetics (looks) along with "all the other things that make your mouth important".

MAIN OUTCOME MEASURES

The participants were asked to indicate on a visual analogue scale how they would value the health of their mouth if they lost the tooth/teeth described and the resultant space was left unrestored.

RESULTS

Overall 152 subjects participated, 78 in Turkey and 74 in Iran with 83 being female and 69 male. Their mean age was 29.5 years (SD 9.3), 62.5% had experienced tooth loss and 37.5% had complete (or completely restored) dentitions. Although there were no differences between the two countries in the degree of utility people attached to anterior teeth, Turkish participants attached significantly more disutility than Iranians to the loss of premolar and molar teeth (p < 0.003).

CONCLUSION

Country of origin had an influence on the value placed on certain parts of the dentition and this effect is independent of the number of missing teeth, gender and age. This implies that attitudes to oral health are influenced by prevalent cultural attitudes more than by function.

Comparison of utility weighted DMFT with patient-reported oral well-being

This study investigated a method of measuring oral health, as opposed to measuring disease. The objective was to compare DMF score and whole mouth utility scores to a patient-reported outcome measure (PROM). Disutility values for lost and restored teeth were used to weight the decayed, missing and filled teeths(DMFTs) of 10 adult patients. This gave two whole mouth utility scores (WMU). These scores were then compared with a patient-reported oral health outcome measure recorded by the use of a visual analogue scale (VAS). The anchors for the VAS were 'my mouth could not be worse' and 'my mouth could not be better'. There was a positive correlation (r = 0.6457) between WMU1 and the patient-reported outcome measure (P < 0.05) and a negative correlation (r = -0.8383) between WMU1 and DMFT which was significant at the P < 0.01 level. There was a statistically significant positive correlation of r = 0.7926 between WMU2 and the patient-reported outcome measure (P < 0.01) and a negative correlation (r = -0.9393) between WMU2 and DMFT (P < 0.01). The Pearson's correlation between DMFT and the patient-reported outcome measure was -0.8757, which was significant at the 0.01 level. Patient reports of their perceived level of health correlate well with DMFT scores. Weighting DMFT scores according to the differential values assigned to missing, or missing and filled, teeth does not increase the degree of correlation between the measure and the patients' personal quantification of their oral health. Decayed, missing and filled teeth therefore seems to adequately capture the patient's sense of well-being.

Students' engagement with their group in a problem-based learning curriculum

INTRODUCTION

In a new enquiry-based learning dental curriculum, problem-based learning (PBL) was chosen as a central methodology because it promotes a collaborative and constructive approach to learning. However, inevitably, some groups function worse than others. This study explores the relationship between group functionality and individuals' results on knowledge-based assessment. It also sought to establish whether using the Belbin team role theory could improve group functionality.

METHODS

Students completed the Belbin team role inventory that assigns individuals to a team role type and were allocated to either an ideal Belbin group or a control group. To evaluate the functionality of the groups, Macgowan's group engagement measure was completed after 18 and 31 weeks for each student by their group facilitator. The scores were summed and averaged giving a group engagement score for each group. Relationships between group engagement, individual performance in assessment in weeks 18 and 31 and Belbin and non-Belbin teams were investigated.

RESULTS

Individual group engagement scores and performance in the knowledge tests had a statistically significant positive relationship despite the small number of students involved (62). However, no correlation was shown between Belbin groups and group engagement scores.

CONCLUSIONS

Those students who engaged most with the PBL process performed markedly better in assessments of knowledge. Using Belbin's team role theory to place students in PBL groups in an effort to increase group functionality had no effect when compared with non-Belbin control groups.

Tooth loss--an assessment of dental health state utility values

OBJECTIVE

The study described aimed to measure the value placed on oral health, by measuring the utility of mouths in which teeth had been lost.

METHODS

A total of 102 subjects who had experienced tooth loss were interviewed and presented with 19 different scenarios of mouths with missing teeth. Each written description was accompanied by a verbal explanation and digital pictures of mouth models. Participants were asked to indicate on a standardized visual analogue scale how they would value the health of their mouth if they had lost the tooth/teeth described and the resulting space was left unrestored.

RESULTS

With a utility value of 0.0 representing the worst possible health state for a mouth and 1.0 representing the best, the mouth with the upper central incisor missing attracted the lowest utility value (utility = 0.16), the one with a missing upper second molar and the missing lower second molar attracted the highest utility values (utility = 0.48, 0.47, respectively). With respect to shortened dental arch (SDA) scenarios, a mouth with a SDA with only the second molar teeth in all quadrants missing attracted the highest utility value (utility = 0.45). A mouth with an extreme SDA with both missing molar and premolar teeth attracted the lowest utility value (utility = 0.06). Both age and gender have a significant influence on how the dentition is valued.

CONCLUSION

It is feasible and possible to derive measurements of the impact of various degrees of tooth loss on individuals. Further studies are required to examine whether past tooth loss or oral health status affects how tooth loss is viewed.

Childhood growth and dental caries

OBJECTIVES

The aim of the study was to examine whether the removal of carious teeth affected children's growth relative to that of a standard population.

DESIGN

Longitudinal prospective observational study.

SETTING

Manchester Dental Hospital (MDH), U.K.

PARTICIPANTS

Five- and six-year-old children who attended for extraction of carious teeth under general anaesthesia.

MAIN OUTCOME MEASURE

Change in height, weight and BMI standard deviation scores during the six months after extraction of carious teeth.

METHODS AND MATERIALS

The children's dental caries levels, weight and height were measured prior to extraction using standard criteria and a single trained examiner and they were then re-measured six months later. The body mass index of the children was calculated and all measurements were converted to standard deviation scores (SDS) using the U.K. 1990 growth reference. Changes in growth SDS during the six months subsequent to the extractions were then calculated.

RESULTS

Two hundred and eighteen children, mean (range) age 5.9 (5-6) were examined initially, of whom 131 were successfully followed up a mean 7.1 (0.13) months later. The participants had a mean dmft of 7.18 (SD 3.27) at baseline and were not shorter than expected (8.3% <10th percentile), or more underweight (6.9% <10th percentile for weight). At follow up children showed a statistically significant gain in BMI SDS (mean (SD) 0.26 (37) p < 0.001) and a small gain in height SDS (0.05 (0.38) p = 0.05).

CONCLUSION

This study suggests that the extraction of carious teeth in five and six year old children promotes weight gain and possibly growth.

Shirley Glasstone Hughes Memorial Prize for Dental Research: an evaluation of the output 15 years after the Trust's inception

In May 2005, a decision was taken by the Shirley Glasstone Hughes (SGH) Foundation trustees to suspend investments in research for one year, to allow a review of the outcomes of SGH research funding over the past 15 years. Money was instead directed to the BDA Research Unit, to employ a staff member who would conduct the evaluation under the supervision of the BDA Scientific Adviser. The evaluation focused on three aspects of the research produced: 1) relevance to primary dental care, 2) scientific quality and impact on the research community, and 3) grant recipients' feelings about SGH funding and whether the mechanisms of supporting research could be improved. The methods used included questioning BDA members about the research they found of interest and relevance, checking research outputs against standardised quality criteria, examining impact factors and citation rates (relative to the funding received) and questioning grant recipients about their experience with SGH funding. The results implied that the fund had largely been spent on research themes felt to be relevant to practice by BDA members. In addition, the publication rate, publication quality, impact and citation indices demonstrated the SGH research work to be largely of high quality. Recipients of the fund indicated several factors which might improve the experience of receiving funding and possibly also improve the research output. It can be concluded that the SGH funds have largely been well spent but that it is worth considering implementing changes which would make the research findings of greater relevance to clinical practice.

Decision analysis of medical and surgical treatments for trigeminal neuralgia: How patient evaluations of benefits and risks affect the utility of treatment decisions

Trigeminal neuralgia (TN) is a rare form of neuropathic facial pain characterised by severe, paroxysmal pains in the face. Little is known about the decision process in treatment of TN, and management with anti-epileptic drugs or surgical procedures carries risks of side effects, recurrence and complications. One hundred fifty-six previously diagnosed TN patients completed an adapted time-trade-off utility measurement questionnaire to ascertain how they valued the potential outcomes from various surgical and medical treatments. The decision analysis revealed that microvascular decompression surgery (MVD) offered the best chance of improved quality of life or highest maximum expected utility (MEU). MVD (MEU=16.08 out of a possible 20) was closely followed by balloon compression (MEU=15.97), percutaneous glycerol rhizolysis (MEU=15.61) and then radiofrequency thermocoagulation (MEU=14.93). Medication offered the least optimal chance of improved quality of life (MEU=14.61). The difference between the highest (MVD) and lowest scoring treatments (medication) was 7.3% (1.46/20). These results were sensitive to some utility values, meaning the preferred treatment is changed by the values patients assign to outcomes. As surgical techniques narrowly offer the highest chance of maximising patient quality of life, all patients with TN should consider surgery. However, surgery is not right for everyone, and patients should be informed about their full range of choices. Treatment decisions must take place after careful consideration of the values patients place on benefits and risks of treatment.

Academic dentistry--where is everybody?

If someone had told us, when we were undergraduates, that there was a career which allowed you the time, and gave you the support, to pursue and research the things about your profession which most interested you, we would have been intrigued. If we had then been informed that there was paid employment which encouraged you to travel extensively abroad, talking about your work, and also gave you the brightest young minds in the country to engage with, teach and learn from, we would have thought this job sounded very tempting. If we had then been told that it also provided secretaries and administrators to help you do your job, and was carried out in a non-hierarchical, collegiate environment where equality and diversity are valued--we would have jumped at the chance! And did! Because what is described above is the life of a clinical academic. Although all the above are part of the role of the academic, there is also immense value and joy to be obtained through scholarship, education and teaching, which are sometimes forgotten because so much of our time and energy is directed to dealing with our patients' problems, while wrestling with the intricacies of new contracts, clinical governance, evidence based practice, and so forth.

Prevention. Part 8: The use of pit and fissure sealants in preventing caries in the permanent dentition of children

This paper reviews evidence concerning the use of pit and fissure sealants in preventing caries in the permanent dentition of children. While the evidence with respect to some sealant types and application techniques is incomplete, systematic reviews have clearly demonstrated that sealants are an effective preventive technology when used in high risk children, and that with proper application techniques long-term retention rates can be achieved. However, careful selection of patients and teeth for sealant placement is required to ensure cost-effectiveness.

A comparison of sensation-seeking between dental and biological science students

AIM

The aim of this study was to compare sensation-seeking behaviour amongst dental students and age-, sex-matched students studying for a standard 3-year degree in biological sciences at the Manchester University.

METHODS

A total of 268 sensation-seeking questionnaires were distributed to second- and third-year male and female dental and biological science students, studying for a degree at the University of Manchester. Each questionnaire was scored against Zuckerman's sensation-seeking scale.

RESULTS

A total of 268 questionnaires were distributed, 175 were returned. The return rate was 65%. The primary findings were: Biological Science students were more sensation-seeking in the dimensions of disinhibition and experience-seeking than dental students (P < 0.05). There was a significant gender bias in sensation-seeking. Males were significantly more sensation-seeking than females in both courses (P < 0.05). Males in both courses had similar sensation-seeking tendencies (NS). Females in the biological sciences course were less inhibited than their dental counterparts (P < 0.05).

CONCLUSIONS

There was a clear difference in sensation-seeking within and between groups of dental students and students studying biological sciences.

Prevention. Part 7: professionally applied topical fluorides for caries prevention

This paper reviews the use of professionally applied topical fluorides (PATF) in caries prevention. PATFs are indicated for children and adults with one or more decayed smooth surfaces and/or those who are at high caries risk. Frequency of administration depends on the patient's caries risk, and is usually every 6 months. The effectiveness of fluoride varnish and gel applications has been well established in caries prevention trials involving permanent teeth. Although both types are effective, varnish may be preferred because it is easier to apply, reduces the risk of fluoride over-ingestion, and has greater patient acceptance. Fluoride foams are similar products to gels, but have not been tested clinically. The use of in-office two-part rinses is not recommended because they have not been proven effective. A cleaning, or prophylaxis, is not necessary before the application of topical fluoride for caries prevention. In conclusion, when used appropriately, PATFs are a safe, effective means of reducing caries risk among high-risk populations.

Prevention. Part 5: Preventive strategies for patients requiring osseointegrated oral implant treatment

Prevention for patients requiring rehabilitation with oral implants is about preventing implant failure and biomechanical complications. This paper describes preventative strategies for the planning stage for implant treatment and the later maintenance period and indicates the level of scientific evidence supporting these strategies.

Prevention. Part 3: prevention of tooth wear

Non-carious destruction of teeth has been observed in archaeological material from various parts of the world and clearly pre-dates the first appearance of dental caries. Attrition, abrasion and erosion are also described in the classic text of Pindborg on the pathology of the dental hard tissues. Whilst the dental profession, at least in affluent parts of the world, was engaged in diagnosing, treating and later preventing dental caries these other causes of tooth destruction were largely ignored.

Prevention. Part 1: smoking cessation advice within the general dental practice

Smoking remains the largest single preventable cause of death and disability in the UK and costs the NHS 1.7 billion pound each year. More than 120,000 people die prematurely due to smoking related diseases. Worldwide smoking is the single most important public health problem. The detrimental effects of smoking and tobacco use on oral health are well recognised. Oral cancers and pre-cancers, periodontal diseases and poor wound healing are the most significant and serious effects of smoking on the mouth. In addition, staining of the teeth, soft tissue changes and halitosis are aesthetic and social impacts of smoking directly related to oral health.

A general dental practice research network: impact of oral health in general dental practice patients

OBJECTIVE

To measure the subjective impact of oral health in a group of patients attending general dental practices in the North West of England and to investigate the attributes of dentists and practices in order to examine how such attributes might relate to patients' subjective perceptions of oral health.

DESIGN

Fifteen general dental practices conducting a simultaneous survey of attending patients and 15 practitioners from these practices providing information about their attitudes to treatment, prevention and various aspects of their surgery.

SETTING

General dental

OUTCOME MEASURES

Patient subjective impact scores. Relationships between practice and practitioner variables and patients' subjectively perceived oral health.

RESULTS

Fifteen practitioners with diverse practice attributes provided data on 718 patients. The mean total oral health impact score was 18.4. Twenty two per cent of patients had experienced pain in the four weeks before the survey and 11% had been unable to chew some foods. Fifty five per cent of the surveyed population had, in the previous year, worried about the appearance of their mouth and 65% had worried about their oral health in general. Dentists' beliefs were related to patient impact scores but practice attributes were not significantly associated with patients' impacts.

CONCLUSIONS

Fourteen percent of the differences in patients' subjectively perceived oral health can be attributed to dentist attitudes and attributes. Further research regarding the influence of dentists personality and professional beliefs on patients well-being needs to be undertaken.

A general dental practice research network--philosophy, activities and participant views

The importance of building research capability among general dental practitioners was highlighted when in 1996 a large tranche of money was released to support research and development in primary dental care. As a result of the links forged by this research opportunity, a group of primary dental care practitioners was recruited into a Primary Dental Network. This network was closely allied to an academic department and the aim was to develop the practitioners' research interest into research skills and finally into a research project. The group therefore attended a series of structured workshops, designed specifically to augment the practitioners' skills using a 'learning by doing' approach. Once the practitioners had acquired the relevant skills, they undertook a research project, which will be reported in a later paper.

Exploring dental patients' preferred roles in treatment decision-making - a novel approach

AIMS

To assess the transferability of the Control Preferences Scale to dental settings and to explore patients' preferred and perceived roles in dental treatment decision-making.

SETTING AND PARTICIPANTS

A convenience sample of 40 patients, 20 recruited from the University Dental Hospital of Manchester and 20 from a general dental practice in Cheshire.

METHODS

A cross-sectional survey, using the Control Preferences Scale, a set of sort cards outlining five decisional roles (active, semi-active, collaborative, semi-passive, passive), slightly modified for use in dental settings. A second set of cards was used to identify perceived decisional role. Rationale for choice of preferred role was recorded verbatim.

RESULTS

The Control Preferences Scale was found to be transferable to dental settings. All patients in the sample had identifiable preferences regarding their role in treatment decision-making. A collaborative decisional role, with patient and dentist equally sharing responsibility for decision-making, was most popular at both sites. However, patients at both sites typically perceived themselves as attaining a passive role in treatment decisions. Lack of knowledge about dentistry and trust in the dentist were reported contributors to a passive decisional role preference, whilst those with more active role preferences gave rationales consistent with a consumerist stance.

CONCLUSIONS

This exploratory study's findings suggest that dental patients have distinct preferences in relation to treatment decision-making role and that these may not always be met during consultations with their dentist. The Control Preferences Scale appears to be appropriate for use in dental settings.

Customer care

Everyone who is in business knows that the most important thing one can achieve is attracting and retaining customers. Now, before the BDJ is bombarded with complaints about ivory-tower academics talking theoretically about something of which they have no experience, I need to tell you that I do have real, live practical experience of business. Okay, it's not a business to do with dentistry, it's a business to do with horses, but nevertheless, it is a business and the basic premises of businesses apply to both dentistry and to riding stables. Remarkably also, there are a number of interesting analogies between running a riding school and running a dental practice!

A two-component regulator of universal stress protein expression and adaptation to oxygen starvation in Mycobacterium smegmatis

We identified a response regulator in Mycobacterium smegmatis which plays an important role in adaptation to oxygen-starved stationary phase. The regulator exhibits strong sequence similarity to DevR/Rv3133c of M. tuberculosis. The structural gene is present on a multigene locus, which also encodes a sensor kinase. A devR mutant of M. smegmatis was adept at surviving growth arrest initiated by either carbon or nitrogen starvation. However, its culturability decreased several orders of magnitude below that of the wild type under oxygen-starved stationary-phase conditions. Two-dimensional gel analysis revealed that a number of oxygen starvation-inducible proteins were not expressed in the devR mutant. Three of these proteins are universal stress proteins, one of which is encoded directly upstream of devR. Another protein closely resembles a proposed nitroreductase, while a fifth protein corresponds to the alpha-crystallin (HspX) orthologue of M. smegmatis. None of the three universal stress proteins or nitroreductase, and a considerably lower amount of HspX was detected in carbon-starved wild-type cultures. A fusion of the hspX promoter to gfp demonstrated that DevR directs gene expression when M. smegmatis enters stationary phase brought about, in particular, by oxygen starvation. To our knowledge, this is the first time a role for a two-component response regulator in the control of universal stress protein expression has been shown. Notably, the devR mutant was 10(4)-fold more sensitive than wild type to heat stress. We conclude that DevR is a stationary-phase regulator required for adaptation to oxygen starvation and resistance to heat stress in M. smegmatis.

A cluster randomized controlled trial testing the effectiveness of a school-based dental health education program for adolescents

OBJECTIVES

This trial investigated the value of a school-based dental health education program in terms of changes in knowledge, reported behavior, and plaque scores.

METHODS

A total of 2,678 pupils with a mean age of 12.1 years attending 28 schools participated in a school-based dental health education program. The study used a cluster randomized controlled study design. The health service administrators stipulated that all participants receive the intervention; to meet this requirement, a rolling program of two six-month periods was utilized. During the first six months, half the adolescents received the intervention program, the other half acting as controls. Throughout a further six-month period, all participants received the intervention program. This research design allowed comparisons between participants receiving the program for six and 12 months. At baseline, six, and 12 months, a random subsample of 40 children in each participating school had their plaque scores recorded and a questionnaire was used to record their knowledge of dental health and reported dental behavior.

RESULTS

The analysis used the subjects clustered within the schools, which were the units of randomization. The intervention program produced statistically significant improvements (P < .001) in knowledge about periodontal disease and the frequency of sugar intake and dental caries in both assessment time periods. The reported frequency of brushing did not change, but the group who had received 12 months of the intervention were more likely (P < .05) to brush for over a minute. At six months the early intervention group had a statistically significant, 13 percent reduction in the mean proportion of sites with plaque compared with the late intervention group (P = .043). This difference was sustained at 12 months (P = .037).

CONCLUSION

This cluster randomized control trial demonstrated that the intervention program resulted in an improvement in knowledge of dental disease and an increase in the reported duration of brushing. These improvements were accompanied by a significant improvement in oral hygiene and a reported reduction in gingival bleeding.

The reasons for the extraction of various tooth types in Scotland: a 15-year follow up

OBJECTIVES

The aim of this survey was to investigate the reasons for extraction of the various tooth types in Scotland. This study replicated one which was undertaken 15 years earlier. A further aim, therefore, was to identify any changes in the frequency of extraction of each tooth type in the 15 years between the two studies.

METHODS

The names of every fourth dentist on the list of the Scottish Dental Practice Board were obtained. Four hundred and twenty-five general dental practitioners were asked to record permanent tooth extractions for 1 week. Data requested for each extraction were: the patient's age, gender and dental attendance pattern, the type of tooth removed and the reason for the extraction.

RESULTS

Three hundred and fifty-two dentists participated (a response rate of 82.8%). There were 25% fewer teeth extracted per patient and 30% fewer per dentist than in the 1984 study. In 1999, more teeth of most types were extracted from regular attenders whereas, in 1984, more teeth of all types were extracted from irregular attenders. Premolars and first and second molars were the tooth types most frequently extracted in both surveys. In 1999 premolars were the teeth most commonly removed below 21 years of age, accounting for 57.5% of extractions in this age range. Molars accounted for 33.8% of extractions in this age range compared with 52% in 1984. Overall, caries was found to be the principal reason for loss of all tooth types apart from lower incisors which were extracted mainly for periodontal reasons. However, below 21 years, 84.5% of premolar extractions were performed for orthodontic purposes.

CONCLUSIONS

Over the last 15 years, the overall number of extractions has reduced and the proportion of extractions from regular attenders has increased. Proportionately more premolars and fewer molars were extracted from under-21-year-olds. This observation can be explained by an increase in orthodontic extractions or a decline in extractions for caries in this age group. However, when extractions from the population as a whole are considered, caries and its sequelae remains the principal reason for loss of all tooth types other than lower incisors which are extracted mainly for periodontal reasons.

Risks and values in treatment decision making

The 1984 Oral Health Strategy defined oral health as a subjective state rather than an objective one. It also made clear that oral health was far more than the mere absence of oral disease. Healthcare outcomes can therefore only be evaluated by the individual receiving healthcare rather than by those who provide it. The task of the healthcare provider is to determine the probability of achieving particular health outcomes. Weighting the value of an outcome by the probability with which it will occur can inform decision-making. The decisions which result from using such a system are sometimes counter-intuitive but ensure that the patient's values are fully incorporated into the decision-making process. This is particularly important in cases where the problem is aesthetic rather than pathological. Patients' evaluations of health outcomes are also known as health state utilities. Even if only considered implicitly, use of utility weighting ensures that patient consent is informed consent and encourages communication and understanding between patient and practitioners.

Treatment planning for the problem patient: restorative, ethical, legal and psychological perspectives. Case 2: Jacqueline

Jacqueline's is the second of a series of four articles that aims to look at some of the problems patients may present with when they visit their dentist. Each article starts with a brief scenario about the hypothetical patient and his/her clinical problems. As well as the clinical problem, each case also raises ethical, legal or psychological problems. All of these issues are discussed and possible management strategies and treatment options described.

The reasons for extraction of permanent teeth in Scotland: a 15-year follow-up study

AIMS

Although Scotland has the highest proportion of edentulous adults in the UK, the frequency of edentulousness has fallen by 21% during the last 20 years. This study, carried out in 1999, was designed to establish whether the reasons for tooth loss have also changed since 1984 when they were last determined.

METHODS

The Scottish Dental Practice Board provided the names of every fourth dentist on its list among which 425 general dental practitioners were identified. They were asked to record permanent tooth extractions for 1 week, specifying the age, sex and dental attendance of patients who underwent extractions and the reasons for these extractions. 352 dentists took part: a response rate of 82.8%.

RESULTS

The study confirmed that there has been a reduction in the number of extractions between 1984 and 1999: there were 25% fewer teeth extracted per patient and 30% fewer per dentist per week. From 0-20 years of age, orthodontics has replaced caries as the commonest reason for extraction and in all age groups over 20 years, caries has become the commonest reason in contrast to 1984 when periodontal disease was the principal reason in patients over 40 years old.

CONCLUSIONS

Caries and its sequelae remain the most important cause of tooth loss throughout adult life in Scotland and, therefore, caries prevention and maintenance of restorations are of great importance at all ages.

An investigation into the value and relevance of oral health promotion leaflets for young adolescents

OBJECTIVES

To determine if oral health promotion leaflets of a novel design and content would be read by, acceptable to and influence 11-12-year-old children.

METHOD

Three related leaflets were incorporated into a dental health education programme aimed at 11-12-year-old children. The leaflets were designed specifically, following consultation with focus groups. They had a romantic story line and emphasised the immediate gains from good dental health, relevant to this age group. A random sample of pupils completed a written questionnaire on the impact of the leaflets at the end of the one-year programme. These sample pupils underwent a clinical examination to measure plaque before and after the programme.

RESULTS

2,678 pupils with a mean age of 12.1 years participated in the programme. 895 were randomly selected to join the assessment study. Most pupils 81%, (725) reported they had read the leaflets; 61% (442) finding them enjoyable to read, 51% (370) attractive to look at and 71% (515) finding the story lines interesting. However, girls appreciated the leaflets more than the boys. There was some suggestion that the leaflets played a positive role in the overall success of the programme in that most pupils 83% (602) reported they thought more about caring for their teeth after reading the leaflets and 58% reported their brushing frequency had increased.

CONCLUSION

The results indicate that for adolescents, leaflets which feature interpersonal relationships are well accepted and can stimulate better oral health behaviour.

Evaluation of computer aided learning in developing clinical decision-making skills

AIM

The aim of this study was to determine whether an educational intervention delivered by a computer aided learning package improved the sensitivity and specificity of dentists' restorative treatment decisions.

METHOD

The study was a randomised controlled study using a Solomon three-group design. Ninety-five dentists were randomly allocated to the three study groups. One group of dentists read the radiographs pre and post an educational intervention, a second group read the radiographs once, after the intervention, and a third group read the radiographs twice, but received no intervention. On each occasion the dentists read 24 surfaces on each of 15 radiographs and made 360 decisions on how certain they were about restoring the tooth surface. Comparisons of mean sensitivity, specificity and areas under ROC curves were made within and between the study groups. Kappa values were used to assess changes in the level of agreement between dentists.

RESULTS

There were no significant changes in sensitivity, specificity or area under ROC curves caused by the intervention. There was no evidence that the level of agreement between the dentists improved after the intervention.

CONCLUSION

A computer aided learning package had no effect on dentists' treatment decision-making behaviour.