Salivary biomarkers in burning mouth syndrome: A systematic review and meta-analysis.

The objective of this systematic review was to evaluate which salivary biomarkers are altered in patients with burning mouth syndrome (BMS) compared to a control group (CG). A comprehensive literature search was conducted in four databases. Case-control studies evaluating salivary biomarkers in BMS patients were included. Risk of bias was assessed using the Newcastle-Ottawa tool. RevMan was used for meta-analysis. Seventeen studies were selected. The included studies collected 54 different biomarkers. Of these biomarkers, only three (cortisol, α-amylase, and dehydroepiandrosterone) were analyzed in three or more studies. Dehydroepiandrosterone obtained contradictory results among the studies. However, cortisol and α-amylase levels were found to be higher in BMS patients. Cortisol was the only biomarker which could be included for meta-analysis. Cortisol levels were significantly higher in the BMS group compared to the CG (Mean Difference = 0.39; 95% CI [0.14-0.65]; p = 0.003). In conclusion, different studies investigated salivary biomarkers in patients with BMS compared to a CG, with controversial results. Meta-analysis, confirmed by trial-sequential analysis, showed how cortisol levels were significantly higher in BMS. Cortisol emerges as an interesting salivary biomarker in BMS, but future properly designed studies are needed to evaluate its role in diagnosis and/or response to treatment.

Evaluation of the diagnostic ability of oral lesions on clinical images among undergraduate dental students.

INTRODUCTION: The dentist should be able to carry out systematic oral examinations of the mucosa of patients in order to diagnose any alterations at an early stage. MATERIALS AND METHODS: An observational, analytical, prospective, and longitudinal study was carried out. 161 students were evaluated at the beginning of their clinical practice in their 4th year of dental school (September 2019), at the beginning and at the end of their 5th year of dental school (June 2021). Thirty oral lesions were projected, and the students were asked to provide an answer; if the lesions were benign, malignant, or potentially malignant, whether they should be biopsied and/or treated and a presumptive diagnosis. RESULTS: Significant improvement (p < .001) was obtained between the 2019 and 2021 results, in relation to the classification, need for biopsy and treatment of lesions. For differential diagnosis, no significant difference (p = .985) was obtained between the 2019 and 2021 responses. Malignant lesions and PMD obtained mixed results, with the best results corresponding to OSCC. DISCUSSION: In this study, a correct lesion classification by the students was over 50%. As for the OSCC, the results were superior to the rest of the images, reaching more than 95% correct. CONCLUSION: Theoretical-practical training from universities and continuing education for graduates in relation to oral mucosal pathologies should be further promoted.

Adaptation of clinical subjects in Dentistry to virtual environments during the COVID-19 pandemic in a Spanish University: A case study.

INTRODUCTION: The evolution of the pandemic has generated a crisis in all areas, also including the faculties of dentistry. We detail how the teaching guides for clinical subjects have been adapted in the Department of Clinical Dentistry at the Universidad Europea of Madrid, moving to a 100% online environment. USUAL DEVELOPMENT OF CLINICAL PRACTICES IN THE DDS DEGREE OF UEM: Students in the fourth and fifth year of DDS degree take the courses "Introduction to Clinical Practice" and "Supervised Practice." Within the framework of continuous assessment, different systems and procedures are used to evaluate knowledge, skills or competences. CURRICULAR ADAPTATION DURING THE PERIOD OF THE COVID-19 PANDEMIC: It was necessary to adapt the practical contents to virtual contents. 35% of the course (12 weeks) was adapted to a 100% online environment. Several activities were carried out that could be evaluated in real time, including lectures, clinical cases and resolution of multidisciplinary dental treatments. DEVELOPMENT OF CLINICAL PRACTICES IN HEALTH EDUCATION IN OTHER INSTITUTIONS DURING THE PANDEMIC: A narrative review was conducted to identify how this situation has been addressed in other institutions and countries; finding that similarly, it has been possible to establish monitoring of clinical practices in a virtual environment. An online questionnaire was conducted to the fourth and fifth year students of DDS degree to stablish the acceptance of the adaptation during the pandemic. CONCLUSION: Despite the limitations of online training for the development of clinical practice, a system has been established to ensure appropriate clinical training for undergraduate students in dentistry. Some of the developments were well accepted by the students.

General health status of a sample of patients with burning mouth syndrome: A case-control study.

BACKGROUND: The relationship of burning mouth syndrome (BMS) with possible alterations in patients' general health has been subject of study and controversy during the last years. OBJECTIVE: To analyse the general health status of patients with BMS, comparing it with a control group. METHODS: A case-control study was conducted to compare the diseases, medications, blood test alterations, disturbances in general health, oral quality of life, xerostomia, sleep quality and psychological status between a group of 20 patients with BMS and a group of 40 patients who did not suffer from this disease. RESULTS: BMS patients suffered more comorbidities and consumed more medications than controls. More mental, behavioural or neurodevelopmental disorders in BMS patients were found, consuming more drugs for nervous and cardiovascular systems, and alimentary tract and metabolism. Lower levels of iron and higher levels of folic acid were found in BMS patients compared to controls. General health status, oral health impact, sleepiness, psychological status and xerostomia levels were also significantly worsened in BMS patients than in controls. CONCLUSIONS: BMS patients presented a worsened health status over controls suffering more comorbidities, consuming more medications and showing adverse results in all the health variables analysed in this study.

Effects of photobiomodulation with low-level laser therapy in burning mouth syndrome: A randomized clinical trial.

BACKGROUND: Photobiomodulation (PBM) has proven to be effective in different painful conditions. OBJECTIVES: To assess the effect of photobiomodulation for pain management in burning mouth syndrome (BMS) patients, besides analysing the impact on different aspects of quality of life. METHODS: A randomized, single-blind, clinical trial was performed among 20 patients with BMS. Photobiomodulation was applied in the study group (n = 10) with a dose of 12 J/cm2 during 10 sessions, comparing with a placebo group (n = 10) with the laser turned off. Pain was assessed using the visual analogue scale (VAS) before starting each treatment session, and at the 1-month and 4-month follow-up appointments. Some validated questionnaires for general health were also complete: SF-36, OHIP-14, Epworth, SCL 90-R and McGill. RESULTS: All patients (n = 10) in the study group improved their pain ending treatment and remaining among 90% (n = 9) in the 4-month follow-up. Significant improvement was found in the study group in some sections of McGill questionnaire, Epworth scale, and SCL 90-R at the end of the treatment and in the 1-month and 4-month follow-ups. CONCLUSIONS: Photobiomodulation seems to be effective in reducing pain in patients with BMS, as well as, having a positive impact on the psychological state of these patients.

Effects of Xerostom® products on xerostomia in primary Sjögren's syndrome: A randomized clinical trial.

OBJECTIVES: To assess the effects of Xerostom® toothpaste and mouthwash in primary Sjögren's syndrome (pSS) patients with xerostomia. SUBJECTS AND METHODS: A double-blinded, randomized study where patients were assigned at baseline test or control products. Patients used the products 3 times/day/28 days. We used a visual analogue scale (VAS) for xerostomia and an Oral Health Impact Profile-14 (OHIP-14), baseline and after treatment, to assess possible improvement. RESULTS: A total of 28 patients with pSS were included in this study, but only 24 finished it (all women, mean age 55.21 ± 11.87), and 13 patients received the test and 11 the control. VAS and OHIP-14 scores decreased in both groups after treatment but significant differences between groups were not found. We do not detect VAS intragroup significant differences before and after treatment in test and control groups. A significant improvement in OHIP-14 was identified in the treatment group, while no significant differences were observed in the control group. No adverse effects were present. CONCLUSIONS: Xerostom® toothpaste and mouthrinse may alleviate and improve quality of life without associated side effects, but further research with a larger number of participants and follow-up are necessary to establish the positive efficacy of these topical products in pSS patients.

A novel peptidoglycan D,L-endopeptidase induced by Salmonella inside eukaryotic cells contributes to virulence.

Bacteria remodel peptidoglycan structure in response to environmental changes. Many enzymes are involved in peptidoglycan metabolism; however, little is known about their responsiveness in a defined environment or the modes they assist bacteria to adapt to new niches. Here, we focused in peptidoglycan enzymes that intracellular bacterial pathogens use inside eukaryotic cells. We identified a peptidoglycan enzyme induced by Salmonella enterica serovar Typhimurium in fibroblasts and epithelial cells. This enzyme, which shows γ-D-glutamyl-meso-diaminopimelic acid D,L-endopeptidase activity, is also produced by the pathogen in media with limited nutrients and in resting conditions. The enzyme, termed EcgA for endopeptidase responding to cessation of growth', is encoded in a S. Typhimurium genomic island absent in Escherichia coli. EcgA production is strictly dependent on the virulence regulator PhoP in extra- and intracellular environments. Consistent to this regulation, a mutant lacking EcgA is attenuated in the mouse typhoid model. These findings suggest that specialised peptidoglycan enzymes, such as EcgA, might facilitate Salmonella adaptation to the intracellular lifestyle. Moreover, they indicate that readjustment of peptidoglycan metabolism inside the eukaryotic cell is essential for host colonisation.

High-throughput, Highly Sensitive Analyses of Bacterial Morphogenesis Using Ultra Performance Liquid Chromatography.

The bacterial cell wall is a network of glycan strands cross-linked by short peptides (peptidoglycan); it is responsible for the mechanical integrity of the cell and shape determination. Liquid chromatography can be used to measure the abundance of the muropeptide subunits composing the cell wall. Characteristics such as the degree of cross-linking and average glycan strand length are known to vary across species. However, a systematic comparison among strains of a given species has yet to be undertaken, making it difficult to assess the origins of variability in peptidoglycan composition. We present a protocol for muropeptide analysis using ultra performance liquid chromatography (UPLC) and demonstrate that UPLC achieves resolution comparable with that of HPLC while requiring orders of magnitude less injection volume and a fraction of the elution time. We also developed a software platform to automate the identification and quantification of chromatographic peaks, which we demonstrate has improved accuracy relative to other software. This combined experimental and computational methodology revealed that peptidoglycan composition was approximately maintained across strains from three Gram-negative species despite taxonomical and morphological differences. Peptidoglycan composition and density were maintained after we systematically altered cell size in Escherichia coli using the antibiotic A22, indicating that cell shape is largely decoupled from the biochemistry of peptidoglycan synthesis. High-throughput, sensitive UPLC combined with our automated software for chromatographic analysis will accelerate the discovery of peptidoglycan composition and the molecular mechanisms of cell wall structure determination.

Chemometric Analysis of Bacterial Peptidoglycan Reveals Atypical Modifications That Empower the Cell Wall against Predatory Enzymes and Fly Innate Immunity.

Peptidoglycan is a fundamental structure for most bacteria. It contributes to the cell morphology and provides cell wall integrity against environmental insults. While several studies have reported a significant degree of variability in the chemical composition and organization of peptidoglycan in the domain Bacteria, the real diversity of this polymer is far from fully explored. This work exploits rapid ultraperformance liquid chromatography and multivariate data analysis to uncover peptidoglycan chemical diversity in the Class Alphaproteobacteria, a group of Gram negative bacteria that are highly heterogeneous in terms of metabolism, morphology and life-styles. Indeed, chemometric analyses revealed novel peptidoglycan structures conserved in Acetobacteria: amidation at the α-(l)-carboxyl of meso-diaminopimelic acid and the presence of muropeptides cross-linked by (1-3) l-Ala-d-(meso)-diaminopimelate cross-links. Both structures are growth-controlled modifications that influence sensitivity to Type VI secretion system peptidoglycan endopeptidases and recognition by the Drosophila innate immune system, suggesting relevant roles in the environmental adaptability of these bacteria. Collectively our findings demonstrate the discriminative power of chemometric tools on large cell wall-chromatographic data sets to discover novel peptidoglycan structural properties in bacteria.

Distinct pathways for modification of the bacterial cell wall by non-canonical D-amino acids.

Production of non-canonical D-amino acids (NCDAAs) in stationary phase promotes remodelling of peptidoglycan (PG), the polymer that comprises the bacterial cell wall. Impairment of NCDAAs production leads to excessive accumulation of PG and hypersensitivity to osmotic shock; however, the mechanistic bases for these phenotypes were not previously determined. Here, we show that incorporation of NCDAAs into PG is a critical means by which NCDAAs control PG abundance and strength. We identified and reconstituted in vitro two (of at least three) distinct processes that mediate NCDAA incorporation. Diverse bacterial phyla incorporate NCDAAs into their cell walls, either through periplasmic editing of the mature PG or via incorporation into PG precursor subunits in the cytosol. Production of NCDAAs in Vibrio cholerae requires the stress response sigma factor RpoS, suggesting that NCDAAs may aid bacteria in responding to varied environmental challenges. The widespread capacity of diverse bacteria, including non-producers, to incorporate NCDAAs suggests that these amino acids may serve as both autocrine- and paracrine-like regulators of chemical and physical properties of the cell wall in microbial communities.

Bile-induced peptidoglycan remodelling in Salmonella enterica.

Changes in the peptidoglycan (PG) structure of Salmonella enterica are detected in the presence of a sublethal concentration of sodium deoxycholate (DOC): (i) lower proportions of Braun lipoprotein (Lpp)-bound muropeptides; (ii) reduced levels of muropeptides cross-linked by L(meso)-diaminopimelyl-D(meso)-diaminopimelic acid (L-D) peptide bridges (3-3 cross-links). Similar structural changes are found in S. enterica cultures adapted to grow in the presence of a lethal concentration of DOC, suggesting that reduced anchoring of Braun protein to PG and low occurrence of 3-3 cross-links may increase S. enterica resistance to bile. This view is further supported by additional observations: (i) A triple mutant lacking L,D-transpeptidases YbiS, ErfK, and YcfS, which does not contain Lpp anchored to PG, is hyper-resistant to bile; (ii) enhanced 3-3 cross-linking upon overexpression of YnhG transpeptidase causes a decrease in bile resistance. These observations suggest that remodelling of the cell wall may be added to the list of adaptive responses that permit survival of S. enterica in the presence of bile.

Polar growth in the Alphaproteobacterial order Rhizobiales.

Elongation of many rod-shaped bacteria occurs by peptidoglycan synthesis at discrete foci along the sidewall of the cells. However, within the Rhizobiales, there are many budding bacteria, in which new cell growth is constrained to a specific region. The phylogeny of the Rhizobiales indicates that this mode of zonal growth may be ancestral. We demonstrate that the rod-shaped bacterium Agrobacterium tumefaciens grows unidirectionally from the new pole generated after cell division and has an atypical peptidoglycan composition. Polar growth occurs under all conditions tested, including when cells are attached to a plant root and under conditions that induce virulence. Finally, we show that polar growth also occurs in the closely related bacteria Sinorhizobium meliloti, Brucella abortus, and Ochrobactrum anthropi. We find that unipolar growth is an ancestral and conserved trait among the Rhizobiales, which includes important mutualists and pathogens of plants and animals.

Structural basis for the broad specificity of a new family of amino-acid racemases.

Broad-spectrum amino-acid racemases (Bsrs) enable bacteria to generate noncanonical D-amino acids, the roles of which in microbial physiology, including the modulation of cell-wall structure and the dissolution of biofilms, are just beginning to be appreciated. Here, extensive crystallographic, mutational, biochemical and bioinformatic studies were used to define the molecular features of the racemase BsrV that enable this enzyme to accommodate more diverse substrates than the related PLP-dependent alanine racemases. Conserved residues were identified that distinguish BsrV and a newly defined family of broad-spectrum racemases from alanine racemases, and these residues were found to be key mediators of the multispecificity of BrsV. Finally, the structural analysis of an additional Bsr that was identified in the bioinformatic analysis confirmed that the distinguishing features of BrsV are conserved among Bsr family members.

Peptidoglycan at its peaks: how chromatographic analyses can reveal bacterial cell wall structure and assembly.

The peptidoglycan (PG) cell wall is a unique macromolecule responsible for both shape determination and cellular integrity under osmotic stress in virtually all bacteria. A quantitative understanding of the relationships between PG architecture, morphogenesis, immune system activation and pathogenesis can provide molecular-scale insights into the function of proteins involved in cell wall synthesis and cell growth. High-performance liquid chromatography (HPLC) has played an important role in our understanding of the structural and chemical complexity of the cell wall by providing an analytical method to quantify differences in chemical composition. Here, we present a primer on the basic chemical features of wall structure that can be revealed through HPLC, along with a description of the applications of HPLC PG analyses for interpreting the effects of genetic and chemical perturbations to a variety of bacterial species in different environments. We describe the physical consequences of different PG compositions on cell shape, and review complementary experimental and computational methodologies for PG analysis. Finally, we present a partial list of future targets of development for HPLC and related techniques.

Eliminating a set of four penicillin binding proteins triggers the Rcs phosphorelay and Cpx stress responses in Escherichia coli.

Penicillin binding proteins (PBPs) are responsible for synthesizing and modifying the bacterial cell wall, and in Escherichia coli the loss of several nonessential low-molecular-weight PBPs gives rise to abnormalities in cell shape and division. To determine whether these proteins help connect the flagellar basal body to the peptidoglycan wall, we surveyed a set of PBP mutants and found that motility in an agar migration assay was compromised by the simultaneous absence of four enzymes: PBP4, PBP5, PBP7, and AmpH. A wild-type copy of any one of these restored migration, and complementation depended on the integrity of the PBP active-site serine. However, the migration defect was caused by the absence of flagella instead of improper flagellar assembly. Migration was restored if the flhDC genes were overexpressed or if the rcsB or cpxR genes were deleted. Thus, migration was inhibited because the Rcs and Cpx stress response systems were induced in the absence of these four specific PBPs. Furthermore, in this situation Rcs induction depended on the presence of CpxR. The results imply that small changes in peptidoglycan structure are sufficient to activate these stress responses, suggesting that a specific cell wall fragment may be the signal being sensed. The fact that four PBPs must be inactivated may explain why large perturbations to the envelope are required to induce stress responses.

Escherichia coli low-molecular-weight penicillin-binding proteins help orient septal FtsZ, and their absence leads to asymmetric cell division and branching.

Escherichia coli cells lacking low-molecular-weight penicillin-binding proteins (LMW PBPs) exhibit morphological alterations that also appear when the septal protein FtsZ is mislocalized, suggesting that peptidoglycan modification and division may work together to produce cell shape. We found that in strains lacking PBP5 and other LMW PBPs, higher FtsZ concentrations increased the frequency of branched cells and incorrectly oriented Z rings by 10- to 15-fold. Invagination of these rings produced improperly oriented septa, which in turn gave rise to asymmetric cell poles that eventually elongated into branches. Branches always originated from the remnants of abnormal septation events, cementing the relationship between aberrant cell division and branch formation. In the absence of PBP5, PBP6 and DacD localized to nascent septa, suggesting that these PBPs can partially substitute for the loss of PBP5. We propose that branching begins when mislocalized FtsZ triggers the insertion of inert peptidoglycan at unusual positions during cell division. Only later, after normal cell wall elongation separates the patches, do branches become visible. Thus, a relationship between the LMW PBPs and cytoplasmic FtsZ ultimately affects cell division and overall shape.

Editorial to the Special Issue "The Effect of Exercise Intensity and Psychological Intervention on Musculoskeletal Disorders".

Musculoskeletal disorders are responsible for the most prevalent form of pain, and necessitate a comprehensive approach to rehabilitation [...].

Homogeneous incorporation of secondary cell wall polysaccharides to the cell wall of Thermus thermophilus HB27.

Regular surface protein layers (S-layers) from most Gram-positive bacteria and from the ancestral bacterium Thermus thermophilus attach to pyruvylated polysaccharides (SCWP) covalently bound to the peptidoglycan through their SLH domain. However, it is not known whether the synthesis of SCWP and S-layer is coordinated enough as to follow a similar pattern of incorporation to the cell wall during growth. In this work we analyse the localization of newly synthesized SCWP on the cell wall of T. thermophilus by immunoelectron microscopy. For this, we obtained mutants with a reduced amount of pyruvylated SCWP through mutation of the csaB gene encoding the SCWP-pyruvylating activity, and its upstream gene csaA, a putative sugar transporter. We hypothesized that CsaA would be required for the synthesis of the SCWP. However, we found that csaA mutants showed only a minor decrease in the amount of SCWP immunodetected on the cell walls in comparison with csaB mutants, revealing its irrelevance in the process. Complementation experiments of csaB mutants with CsaB expressed from inducible promoters revealed that newly synthesized SCWP was homogeneously distributed along the cell wall. Fusions with thermostable fluorescent protein revealed that CsaB was distributed also in homogeneous pattern associated with the membrane. These data support that synthesis of SCWP takes place in disperse and homogeneous form all over the cell surface, in contrast to the zonal incorporation at the cell centre recently demonstrated for SlpA.

Localized synthesis of the outer envelope from Thermus thermophilus.

In agreement with its distinct phylogenetic origin, the envelope of Thermus thermophilus consists of a complex pattern of layers with properties intermediate between those of Gram positives and Proteobacteria. Its cell wall of Gram positive composition is surrounded by an outer envelope that includes a crystalline layer scaffold built up by the SlpA protein, lipids and polysaccharides. The synthesis of this outer envelope has been studied by confocal microscopy. Available amino groups from the cell surface, mainly belonging to the SlpA protein, were covalently labelled in vivo with fluorescent dyes. Stained cells were able to grow without any apparent loss of viability, allowing the localization of the regions of new synthesis as dark nonfluorescent spots. Our results demonstrate that the outer envelope of T. thermophilus is synthesized from a central point in the cells, likely following a helical pattern. Cell poles and subpolar regions are basically inert and retain their label for generations.