Xylitol is prothrombotic and associated with cardiovascular risk.

BACKGROUND AND AIMS: The pathways and metabolites that contribute to residual cardiovascular disease risks are unclear. Low-calorie sweeteners are widely used sugar substitutes in processed foods with presumed health benefits. Many low-calorie sweeteners are sugar alcohols that also are produced endogenously, albeit at levels over 1000-fold lower than observed following consumption as a sugar substitute. METHODS: Untargeted metabolomics studies were performed on overnight fasting plasma samples in a discovery cohort (n = 1157) of sequential stable subjects undergoing elective diagnostic cardiac evaluations; subsequent stable isotope dilution liquid chromatography tandem mass spectrometry (LC-MS/MS) analyses were performed on an independent, non-overlapping validation cohort (n = 2149). Complementary isolated human platelet, platelet-rich plasma, whole blood, and animal model studies examined the effect of xylitol on platelet responsiveness and thrombus formation in vivo. Finally, an intervention study was performed to assess the effects of xylitol consumption on platelet function in healthy volunteers (n = 10). RESULTS: In initial untargeted metabolomics studies (discovery cohort), circulating levels of a polyol tentatively assigned as xylitol were associated with incident (3-year) major adverse cardiovascular event (MACE) risk. Subsequent stable isotope dilution LC-MS/MS analyses (validation cohort) specific for xylitol (and not its structural isomers) confirmed its association with incident MACE risk [third vs. first tertile adjusted hazard ratio (95% confidence interval), 1.57 (1.12-2.21), P < .01]. Complementary mechanistic studies showed xylitol-enhanced multiple indices of platelet reactivity and in vivo thrombosis formation at levels observed in fasting plasma. In interventional studies, consumption of a xylitol-sweetened drink markedly raised plasma levels and enhanced multiple functional measures of platelet responsiveness in all subjects. CONCLUSIONS: Xylitol is associated with incident MACE risk. Moreover, xylitol both enhanced platelet reactivity and thrombosis potential in vivo. Further studies examining the cardiovascular safety of xylitol are warranted.

Altered sterol composition mediates multiple tolerance of Kluyveromyces marxianus for xylitol production.

BACKGROUND: Currently, the synthesis of compounds based on microbial cell factories is rapidly advancing, yet it encounters several challenges. During the production process, engineered strains frequently encounter disturbances in the cultivation environment or the impact of their metabolites, such as high temperature, acid-base imbalances, hypertonicity, organic solvents, toxic byproducts, and mechanical damage. These stress factors can constrain the efficiency of microbial fermentation, resulting in slow cell growth, decreased production, significantly increased energy consumption, and other issues that severely limit the application of microbial cell factories. RESULTS: This study demonstrated that sterol engineering in Kluyveromyces marxianus, achieved by overexpressing or deleting the coding genes for the last five steps of ergosterol synthase (Erg2-Erg6), altered the composition and ratio of sterols in its cell membrane, and affected its multiple tolerance. The results suggest that the knockout of the Erg5 can enhance the thermotolerance of K. marxianus, while the overexpression of the Erg4 can improve its acid tolerance. Additionally, engineering strain overexpressed Erg6 improved its tolerance to elevated temperature, hypertonic, and acid. YZB453, obtained by overexpressing Erg6 in an engineering strain with high efficiency in synthesizing xylitol, produced 101.22 g/L xylitol at 45oC and 75.11 g/L xylitol at 46oC. Using corncob hydrolysate for simultaneous saccharification and fermentation (SSF) at 46oC that xylose released from corncob hydrolysate by saccharification with hemicellulase, YZB453 can produce 45.98 g/L of xylitol, saving 53.72% of the cost of hemicellulase compared to 42oC. CONCLUSIONS: This study elucidates the mechanism by which K. marxianus acquires resistance to various antifungal drugs, high temperatures, high osmolarity, acidity, and other stressors, through alterations in the composition and ratio of membrane sterols. By employing sterol engineering, the fermentation temperature of this unconventional thermotolerant K. marxianus was further elevated, ultimately providing an efficient platform for synthesizing high-value-added xylitol from biomass via the SSF process at temperatures exceeding 45 °C.

Engineering of Aspergillus niger for efficient production of D-xylitol from L-arabinose.

D-Xylitol is a naturally occurring sugar alcohol present in diverse plants that is used as an alternative sweetener based on a sweetness similar to sucrose and several health benefits compared to conventional sugar. However, current industrial methods for D-xylitol production are based on chemical hydrogenation of D-xylose, which is energy-intensive and environmentally harmful. However, efficient conversion of L-arabinose as an additional highly abundant pentose in lignocellulosic materials holds great potential to broaden the range of applicable feedstocks. Both pentoses D-xylose and L-arabinose are converted to D-xylitol as a common metabolic intermediate in the native fungal pentose catabolism.To engineer a strain capable of accumulating D-xylitol from arabinan-rich agricultural residues, pentose catabolism was stopped in the ascomycete filamentous fungus Aspergillus niger at the stage of D-xylitol by knocking out three genes encoding enzymes involved in D-xylitol degradation (ΔxdhA, ΔsdhA, ΔxkiA). Additionally, to facilitate its secretion into the medium, an aquaglyceroporin from Saccharomyces cerevisiae was tested. In S. cerevisiae, Fps1 is known to passively transport glycerol and is regulated to convey osmotic stress tolerance but also exhibits the ability to transport other polyols such as D-xylitol. Thus, a constitutively open version of this transporter was introduced into A. niger, controlled by multiple promoters with varying expression strengths. The strain expressing the transporter under control of the PtvdA promoter in the background of the pentose catabolism-deficient triple knock-out yielded the most favorable outcome, producing up to 45% D-xylitol from L-arabinose in culture supernatants, while displaying minimal side effects during osmotic stress. Due to its additional ability to extract D-xylose and L-arabinose from lignocellulosic material via the production of highly active pectinases and hemicellulases, A. niger emerges as an ideal candidate cell factory for D-xylitol production from lignocellulosic biomasses rich in both pentoses.In summary, we are showing for the first time an efficient biosynthesis of D-xylitol from L-arabinose utilizing a filamentous ascomycete fungus. This broadens the potential resources to include also arabinan-rich agricultural waste streams like sugar beet pulp and could thus help to make alternative sweetener production more environmentally friendly and cost-effective.

Effect of Xylitol on Inhibition and Eradication of Pseudomonas aeruginosa PAO1 and Methicillin-Resistant Staphylococcus aureus Biofilms in an Alginate Bead Model.

Biofilms formed by Pseudomonas aeruginosa and Staphylococcus aureus, along with their antibiotic tolerance have posed challenges to treatment strategies for lung, wound, and other infections, particularly when co-infecting. In the present study, the inhibitory effect of xylitol on biofilm formation, as well as its eradication potential on pre-established biofilms formed by P. aeruginosa strain PAO1, methicillin-resistant S. aureus, and a mix of both species in an alginate bead model were tested. Xylitol concentrations of 2, 1, and 0.5 M reduced biofilm formation by P. aeruginosa strain PAO1, methicillin-resistant S. aureus, and the mixed-species biofilm in a concentration-dependent manner. Additionally, biofilms formed by these species were subjected to treatment with xylitol. Xylitol was also capable of eradicating biofilms established by P. aeruginosa strain PAO1, methicillin-resistant S. aureus, and the mixed-species biofilm by at least 20%, with the most effective eradication observed for P. aeruginosa strain PAO1. The present study indicates the effectiveness of xylitol as both an inhibitory and eradicating agent against biofilms formed by P. aeruginosa strain PAO1, methicillin-resistant S. aureus, and a mix of both species in an alginate bead model, which mimics the in vivo characteristics of P. aeruginosa aggregates.

Combined eutexia and amorphization for simultaneous enhancement of dissolution rate of triamterene and hydrochlorothiazide: preparation of orodispersible tablets.

BACKGROUND: Triamterene is an oral antihypertensive drug with dissolution-limited poor bioavailability. It can be used as monotherapy or in fixed dose combination with hydrochlorothiazide which also suffers from poor dissolution. Moreover, co-processing of drugs in fixed dose combination can alter their properties. Accordingly, pre-formulation studies should investigate the effect of co-processing and optimize the dissolution of drugs before and after fixed dose combination. This is expected to avoid deleterious interaction (if any) and to hasten the biopharmaceutical properties. OBJECTIVE: Accordingly, the aim of this work was to optimize the dissolution rate of triamterene alone and after fixed dose combination with hydrochlorothiazide. METHODOLOGY: Triamterene was subjected to dry co-grinding with xylitol, HPMC-E5 or their combination. The effect of co-grinding with hydrochlorothiazide was also tested in absence and presence of xylitol and HPMC-E5. The products were assessed using Fourier-transform infrared (FTIR), differential scanning calorimetry, X-ray powder diffraction (XRPD), in addition to dissolution studies. Optimum formulations were fabricated as oral disintegrating tablets (ODT).Results: Co-processing of triamterene with xylitol formed eutectic system which hastened dissolution rate. HPMC-E5 resulted in partial amorphization and improved triamterene dissolution. Co-grinding with both materials combined their effects. Co-processing of triamterene with hydrochlorothiazide resulted in eutexia but the product was slowly dissolving due to aggregation. This problem was vanished in presence of HPMC-E5 and xylitol. Compression of the optimum formulation into ODT underwent fast disintegration and liberated acceptable amounts of both drugs. CONCLUSION: The study introduced simple co-processing with traditional excipients for development of ODT of triamterene and hydrochlorothiazide.

Development of a novel direct compressible co-processed excipient and its application for formulation of Mirtazapine orally disintegrating tablets.

INTRODUCTION: Orally disintegrating tablets (ODTs) are designed to dissolve in the oral cavity within 3 min, providing a convenient option for patients as they can be taken without water. Direct compression is the most common method used for ODTs formulations. However, the availability of single composite excipients with desirable characteristics such as good compressibility, fast disintegration, and a good mouthfeel suitable for direct compression is limited. OBJECTIVE: This research was proposed to develop a co-processed excipient composed of xylitol, mannitol, and microcrystalline cellulose for the formulation of ODTs. METHODS: A total of 11 formulations of co-processed excipients with different ratios of ingredients were prepared, which were then compressed into ODTs, and their characteristics were thoroughly examined. The primary focus was on evaluating the disintegration time and hardness of the tablets, as these factors are important in ensuring the ODTs meet the desired criteria. The model drug, Mirtazapine was then incorporated into the chosen optimized formulation. RESULTS: The results showed that the formulation comprised of 10% xylitol, 10% mannitol and 80% microcrystalline cellulose demonstrated the fastest disintegration time (1.77 ± 0.119 min) and sufficient hardness (3.521 ± 0.143 kg) compared to the other formulations. Furthermore, the drug was uniformly distributed within the tablets and fully released within 15 min. CONCLUSION: Therefore, the developed co-processed excipients show great potential in enhancing the functionalities of ODTs, offering a promising solution to improve the overall performance and usability of ODTs in various therapeutic applications.

Comparative Conformational Analysis of Acyclic Sugar Alcohols Ribitol, Xylitol and d-Arabitol by Solution NMR and Molecular Dynamics Simulations.

Ribitol (C5H12O5) is an acyclic sugar alcohol that was recently identified in O-mannose glycan on mammalian α-dystroglycan. The conformation and dynamics of acyclic sugar alcohols such as ribitol are dependent on the stereochemistry of the hydroxyl groups; however, the dynamics are not fully understood. To gain insights into the conformation and dynamics of sugar alcohols, we carried out comparative analyses of ribitol, d-arabitol and xylitol by a crystal structure database search, solution NMR analysis and molecular dynamics (MD) simulations. The crystal structures of the sugar alcohols showed a limited number of conformations, suggesting that only certain stable conformations are prevalent among all possible conformations. The three-bond scholar coupling constants and exchange rates of hydroxyl protons were measured to obtain information on the backbone torsion angle and possible hydrogen bonding of each hydroxyl group. The 100 ns MD simulations indicate that the ribitol backbone has frequent conformational transitions with torsion angles between 180∘ and ±60∘, while d-arabitol and xylitol showed fewer conformational transitions. Taking our experimental and computational data together, it can be concluded that ribitol is more flexible than d-arabitol or xylitol, and the flexibility is at least in part defined by the configuration of the OH groups, which may form intramolecular hydrogen bonds.

Xylitol biosynthesis enhancement by Candida tropicalis via medium, process parameter optimization, and co-substrate supplementation.

The present study examines the impact of nitrogen sources (yeast extract, ammonium sulfate peptone, ammonium nitrate, urea, and sodium nitrate), salt solution (0.5 g/L MgSO4, 0.5 g/L KH2PO4, 0.3 g/L CaCl2), trace elements solution (0.1 g/L CuSO4, 0.1 g/L FeSO4, 0.02 g/L MnCl2, 0.02 g/L ZnSO4), operational parameters (temperature, aeration, agitation, initial pH and xylose concentration) and co- substrate supplementation (glucose, fructose, maltose, sucrose, and glycerol) on xylitol biosynthesis by Candida tropicalis ATCC 13803 using synthetic xylose. The significant medium components were identified using the Plackett Burman design followed by central composite designs to obtain the optimal concentration for the critical medium components in shaker flasks. Subsequently, the effect of operational parameters was examined using the One Factor At a Time method, followed by the impact of five co-substrates on xylitol biosynthesis in a 1 L bioreactor. The optimal media components and process parameters are as follows: peptone: 12.68 g/L, yeast extract: 6.62 g/L, salt solution (0.5 g/L MgSO4, 0.5 g/L KH2PO4, and 0.3 g/L CaCl2): 1.23 X (0.62 g/L, 0.62 g/L, and 0.37 g/L respectively), temperature: 30 °C, pH: 6, agitation: 400 rpm, aeration: 1 vvm, and xylose: 50 g/L. Optimization studies resulted in xylitol yield and productivity of 0.71 ± 0.004 g/g and 1.48 ± 0.018 g/L/h, respectively. Glycerol supplementation (2 g/L) further improved xylitol yield (0.83 ± 0.009 g/g) and productivity (1.87 ± 0.020 g/L/h) by 1.66 and 3.12 folds, respectively, higher than the unoptimized conditions thus exhibiting the potential of C. tropicalis ATCC 13803 being used for commercial xylitol production.

Detoxification of areca nut acid hydrolysate and production of xylitol by Candida tropicalis (MTCC 6192).

Areca nut husk is the most promising alternative source of low-cost raw materials because it contains a considerable amount of five-carbon monosaccharide sugar in the form of xylose. This polymeric sugar can be isolated and transformed into a value-added chemical using fermentation. To extract sugars from areca nut husk fibers, preliminary pretreatment, such as dilute acid hydrolysis (H2SO4), was performed. The hemicellulosic hydrolysate of areca nut husk can produce xylitol through fermentation, but toxic components inhibit the growth of microorganisms. To overcome this, a series of detoxification treatments, including pH adjustment, activated charcoal, and ion exchange resin, were carried out to reduce the concentration of inhibitors in the hydrolysate. This study reports a remarkable 99% removal of inhibitors in the hemicellulosic hydrolysate. Subsequently, a fermentation process using Candida tropicalis (MTCC6192) was executed with the detoxified hemicellulosic hydrolysate of areca nut husk, yielding an optimum xylitol yield of 0.66 g/g. This study concludes that detoxification techniques like pH adjustment, activated charcoal, and ion exchange resins are the most economical and effective methods for eliminating toxic compounds in hemicellulosic hydrolysates. Therefore, the medium derived after detoxification from areca nut hydrolysate may be considered to have significant potential for xylitol production.

Application of multiple-intake temporal check all that apply: a case study of strawberry yoghurt formulated with alternative sweeteners.

BACKGROUND: It is crucial to reduce the high sugar content of fruit yoghurts in response to the excessive weight gain epidemic. The use of alternative sweeteners in yoghurts is often associated with the negative sensory attributes that can have an impact on yoghurt liking. The main objective of this research was to investigate the effect of alternative sweeteners and strawberry puree addition on the temporal sensory profile of yoghurt using multiple-intake temporal check all that apply (TCATA). A novel approach to the statical analysis of the temporal sensory data was employed by using aligned rank transformation-analysis of variance to investigate the differences between sensory attributes within different products and within different intakes. RESULTS: Results showed that the attributes sweet and fruity decreased when the concentration of fruit puree was increased at low concentration of sucrose. Interestingly, when the concentration of fruit puree was increased, fruitiness increased and mouthcoating decreased at low concentration of stevia. With successive intakes, the attributes sweet, sour, creamy and fruity significantly decreased in yoghurts sweetened with sucrose, xylitol and stevia. Yoghurts containing low concentrations of sucrose or xylitol and fruit puree were liked the most. However, stevia-sweetened yoghurts varying in sweetener and puree concentration were not significantly different in liking. In order to investigate the consumer acceptance of yoghurts, a novel approach was used - that is, utilizing TCATA temporal data to investigate temporal drivers of liking for each yoghurt type. CONCLUSION: The use of multiple statistical analysis to analyse temporal data suggested that both sweetener and puree concentration need to be considered when developing products using alternative sweeteners. © 2023 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Do chewing gums and sweets containing xylitol prevent caries in children?

DATA SOURCES: Three electronic databases (Pubmed, Embase and the Cochrane Library) were searched in December 2022, and again for additional literature on 3-5th January 2023. Reference lists of relevant systematic reviews were hand searched for other eligible studies for inclusion. STUDY SELECTION: Randomised controlled clinical trials and controlled clinical trials conducted on children (aged ≤ 18 years), conducted between 1974-2022 and available in English, were eligible for inclusion. Studies were excluded if caries was not an outcome, the control group was not sufficient, they were lab-based studies or studies where xylitol delivery was not a sweet or chewing gum and where the xylitol product contained a component such as fluoride which may influence the outcomes. DATA EXTRACTION AND SYNTHESIS: Four calibrated reviewers independently screened titles and abstracts, and disagreements were resolved via group discussion. Preventative effect was determined by comparing the mean caries increment in the control and intervention groups, producing a preventative fraction. A total of 617 titles were initially screened for relevance. After duplicate removal, 268 abstracts were screened and 16 full text articles reviewed, with one more study then excluded. 10 studies investigated xylitol-containing chewing gum, and six looked at xylitol candy (one did both). Eight included studies were randomised controlled trials. Data extraction was undertaken by two reviewers. RESULTS: 3466 participants were included in the 10 studies that investigated xylitol chewing gum, and all 10 studies reported a statistically significant preventive effect compared to a no chewing gum or placebo control. In 9 studies, the preventive fraction was clinically significant. The six studies investigating xylitol candies contained a total of 1023 participants, and only one study demonstrated a significant preventative effect. CONCLUSIONS: There is some evidence that incorporating xylitol chewing gum daily has a caries-reducing effect in those with a moderate-to-high baseline caries level. This effect was not present for xylitol sweets.

Xylitol in toothpaste: is it effective in reducing the levels of Streptococcus mutans in high caries risk young children?

DESIGN: This study is an observational prospective longitudinal cohort study, following 102 children aged 1 to 12 months over a period of 24 months. At baseline, a dental examination was carried out to assess the number of carious lesions present using the ICDAS system, and a saliva sample was taken to assess the levels of Streptococcus mutans (SM) in saliva using the Dentocult SM saliva strip. Cohort caregivers received toothbrushing instruction and a 25% xylitol toothpaste tube for which they were instructed to use twice a day over a 3-month period, after which they returned to clinic at Pristina University to receive another tube. This process continued throughout the entire 24-month study period. At the end of the study, SM prevalence was recorded again. COHORT SELECTION: 102 children and their mothers were included in this study: 43 girls and 59 boys. At the beginning of the study, the child's mean age was 6.7 months, and at the end, 30.8 months. A random sample of 60 mothers was selected to analyse SM levels. DATA ANALYSIS: The data set was summarised descriptively using summary statistics, percentages and statistical tests. Values were expressed as a mean and standard deviation. SM prevalence comparison between baseline and endpoint was tested using chi-square statistics. RESULTS: At the baseline dental examination, the child's mean age was 6.7 (±3.7 months). At this point 59% of the 102 infants were edentulous. Caries was reported to be present in 12.4% of children. The mean ICDAS score was calculated as 0.70 (2.42 SD). When caries was present (87.6% of the 102 children included in the study), the majority of the caries experience (74.2%) was determined as at an early stage (ICAS score 1 or 2). 72.6% (n = 74/102) of children were infected with SM at baseline. 28 children had Level 1 (0) SM. 57 children had Level 2 and 3 (102-4) SM. 17 children had Level 4 SM (≥105) SM. The SM categorical distribution was statistically significant (p = 0.02). At endpoint, 53.5% (57/102) of children were SM infected. Parallel comparison of pre- and post-data sets show that there was a 19.1% reduction in SM levels overall following the introduction of the xylitol toothpaste. (p = 0.002). In the participant group with the highest SM level (Level 4), a net 12.2% reduction in SM prevalence occurred. The change in SM infection was deemed statistically significant. CONCLUSIONS: Brushing twice a day with toothpaste containing 25% xylitol shows a statistically significant decrease in SM levels. This shows a promising anticariogenic effect. Late SM colonisation is protective for future carious lesions. Xylitol can help prevent early childhood caries and early SM contamination.

Xylitol binding to the M1 site of glucose isomerase induces a conformational change in the substrate binding channel.

Glucose isomerase (GI) is extensively used in the food industry for production of high-fructose corn syrup and for the production of biofuels and other renewable chemicals. Structure-based studies on GI inhibitors are important for improving its efficiency in industrial applications. Here, we report the subatomic crystal structure of Streptomyces rubiginosus GI (SruGI) complexed with its inhibitor, xylitol, at 0.99 Å resolution. Electron density map and temperature factor analysis showed partial binding of xylitol to the M1 metal binding site of SruGI, providing two different conformations of the metal binding site and the substrate binding channel. The xylitol molecule induced a conformational change in the M2 metal ion-interacting Asp255 residue, which subsequently led to a conformational change in the side chain of Asp181 residue. This led to the positional shift of Pro25 by 1.71 Å and side chain rotation of Phe26 by 21°, where located on the neighboring protomer in tetrameric SruGI. The conformation change of these two residues affect the size of the substrate-binding channel of GI. Therefore, xylitol binding to M1 site of SruGI induces not only a conformational changes of the metal-binding site, but also conformational change of substrate-binding channel of the tetrameric SruGI. These results expand our knowledge about the mechanism underlying the inhibitory effect of xylitol on GI.

Development of engineered Candida tropicalis strain for efficient corncob-based xylitol-ethanol biorefinery.

BACKGROUND: Xylitol has a wide range of applications in the pharmaceuticals, cosmetic, food and beverage industry. Microbial xylitol production reduces the risk of contamination and is considered as environment friendly and sustainable compared to the chemical method. In this study, random mutagenesis and genetic engineering approaches were employed to develop Candida tropicalis strains with reduced xylitol dehydrogenase (XDH) activity to eliminate co-substrate requirement for corn cob-based xylitol-ethanol biorefinery. RESULTS: The results suggest that when pure xylose (10% w/v) was fermented in bioreactor, the Ethyl methane sulfonate (EMS) mutated strain (C. tropicalis K2M) showed 9.2% and XYL2 heterozygous (XYL2/xyl2Δ::FRT) strain (C. tropicalis K21D) showed 16% improvement in xylitol production compared to parental strain (C. tropicalis K2). Furthermore, 1.5-fold improvement (88.62 g/L to 132 g/L) in xylitol production was achieved by C. tropicalis K21D after Response Surface Methodology (RSM) and one factor at a time (OFAT) applied for media component optimization. Finally, corncob hydrolysate was tested for xylitol production in biorefinery mode, which leads to the production of 32.6 g/L xylitol from hemicellulosic fraction, 32.0 g/L ethanol from cellulosic fraction and 13.0 g/L animal feed. CONCLUSIONS: This work, for the first time, illustrates the potential of C. tropicalis K21D as a microbial cell factory for efficient production of xylitol and ethanol via an integrated biorefinery framework by utilising lignocellulosic biomass with minimum waste generation.

Relation of xylitol formation and lignocellulose degradation in yeast.

One of the critical steps of the biotechnological production of xylitol from lignocellulosic biomass is the deconstruction of the plant cell wall. This step is crucial to the bioprocess once the solubilization of xylose from hemicellulose is allowed, which can be easily converted to xylitol by pentose-assimilating yeasts in a microaerobic environment. However, lignocellulosic toxic compounds formed/released during plant cell wall pretreatment, such as aliphatic acids, furans, and phenolic compounds, inhibit xylitol production during fermentation, reducing the fermentative performance of yeasts and impairing the bioprocess productivity. Although the toxicity of lignocellulosic inhibitors is one of the biggest bottlenecks of the biotechnological production of xylitol, most of the studies focus on how much xylitol production is inhibited but not how and where cells are affected. Understanding this mechanism is important in order to develop strategies to overcome lignocellulosic inhibitor toxicity. In this mini-review, we addressed how these inhibitors affect both yeast physiology and metabolism and consequently xylose-to-xylitol bioconversion. In addition, this work also addresses about cellular adaptation, one of the most relevant strategies to overcome lignocellulosic inhibitors toxicity, once it allows the development of robust and tolerant strains, contributing to the improvement of the microbial performance against hemicellulosic hydrolysates toxicity. KEY POINTS: • Impact of lignocellulosic inhibitors on the xylitol production by yeasts • Physiological and metabolic alterations provoked by lignocellulosic inhibitors • Cell adaptation as an efficient strategy to improve yeast's robustness.

Nebulised hypertonic saline for cystic fibrosis.

BACKGROUND: Hypertonic saline enhances mucociliary clearance and may lessen the destructive inflammatory process in the airways. This is an update of a previously published review. OBJECTIVES: To investigate efficacy and tolerability of nebulised hypertonic saline treatment in people with cystic fibrosis (CF) compared to placebo or other treatments that enhance mucociliary clearance. SEARCH METHODS: We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group's Cystic Fibrosis Trials Register, comprising references identified from comprehensive electronic database searches, handsearches of relevant journals and abstract books of conference proceedings. We also searched ongoing trials databases. Most recent search: 25 April 2022. SELECTION CRITERIA: We included randomised and quasi-randomised controlled trials assessing hypertonic saline compared to placebo or other mucolytic therapy, for any duration or dose regimen in people with CF (any age or disease severity). DATA COLLECTION AND ANALYSIS: Two authors independently reviewed all identified trials and data, and assessed trial quality. We assessed the certainty of the evidence using GRADE. For cross-over trials we stipulated a one-week washout period. We planned to use results from a paired analysis in the review, but this was only possible in one trial. For other cross-over trials, we chose to treat the trials as if they were parallel. MAIN RESULTS: We included 24 trials (1318 participants, aged one month to 56 years); we excluded 29 trials, two trials are ongoing and six are awaiting classification. We judged 15 of the 24 included trials to have a high risk of bias due to participants' ability to discern the taste of the solutions. Hypertonic saline 3% to 7% versus placebo (stable disease) We are uncertain whether the regular use of nebulised hypertonic saline in stable lung disease leads to an improvement in forced expiratory volume in one second (FEV1) % predicted at four weeks, (mean difference (MD) 3.30%, 95% confidence interval (CI) 0.71 to 5.89; 4 trials, 246 participants; very low-certainty evidence). In preschool children we found no difference in lung clearance index (LCI) at four weeks, but a small improvement after 48 weeks of treatment with hypertonic saline compared to isotonic saline (MD -0.60, 95% CI -1.00 to -0.19; 2 trials, 192 participants). We are also uncertain whether hypertonic saline made a difference to mucociliary clearance, pulmonary exacerbations or adverse events compared to placebo. Hypertonic saline versus control (acute exacerbation) Two trials compared hypertonic saline to control, but only one provided data. There may be little or no difference in lung function measured by FEV1 % predicted after hypertonic saline compared to isotonic saline (MD 5.10%, 95% CI -14.67 to 24.87; 1 trial, 130 participants). Neither trial reported any deaths or measures of sputum clearance. There were no serious adverse events. Hypertonic saline versus rhDNase Three trials compared a similar dose of hypertonic saline to recombinant deoxyribonuclease (rhDNase); two trials (61 participants) provided data for inclusion in the review. We are uncertain whether there was an effect of hypertonic saline on FEV1 % predicted after three weeks (MD 1.60%, 95% CI -7.96 to 11.16; 1 trial, 14 participants; very low-certainty evidence). At three months, rhDNase may lead to a greater increase in FEV1 % predicted than hypertonic saline (5 mL twice daily) at 12 weeks in participants with moderate to severe lung disease (MD 8.00%, 95% CI 2.00 to 14.00; low-certainty evidence). We are uncertain whether adverse events differed between the two treatments. No deaths were reported. Hypertonic saline versus amiloride One trial (12 participants) compared hypertonic saline to amiloride but did not report on most of our outcomes. The trial found that there was no difference between treatments in measures of sputum clearance (very low-certainty evidence). Hypertonic saline compared with sodium-2-mercaptoethane sulphonate (Mistabron®) One trial (29 participants) compared hypertonic saline to sodium-2-mercaptoethane sulphonate. The trial did not measure our primary outcomes. There was no difference between treatments in any measures of sputum clearance, courses of antibiotics or adverse events (very low-certainty evidence). Hypertonic saline versus mannitol One trial (12 participants) compared hypertonic saline to mannitol, but did not report lung function at relevant time points for this review; there were no differences in sputum clearance, but mannitol was reported to be more 'irritating' (very low-certainty evidence). Hypertonic saline versus xylitol Two trials compared hypertonic saline to xylitol, but we are uncertain whether there is any difference in FEV1 % predicted or median time to exacerbation between groups (very low-certainty evidence). No other outcomes were reported in the review. Hypertonic saline 7% versus hypertonic saline 3% We are uncertain whether there was an improvement in FEV1 % predicted after treatment with 7% hypertonic saline compared with 3% (very low-certainty evidence). AUTHORS' CONCLUSIONS: We are very uncertain if regular use of nebulised hypertonic saline by adults and children over the age of 12 years with CF results in an improvement in lung function after four weeks (three trials; very low-certainty evidence); there was no difference seen at 48 weeks (one trial; low-certainty evidence). Hypertonic saline improved LCI modestly in children under the age of six years. Evidence from one small cross-over trial in children indicates that rhDNase may lead to better lung function than hypertonic saline at three months; qualifying this, we highlight that while the study did demonstrate that the improvement in FEV1 was greater with daily rhDNase, there were no differences seen in any of the secondary outcomes. Hypertonic saline does appear to be an effective adjunct to physiotherapy during acute exacerbations of lung disease in adults. However, for the outcomes assessed, the certainty of the evidence ranged from very low to low at best, according to the GRADE criteria. The role of hypertonic saline in conjunction with cystic fibrosis transmembrane conductance regulator (CFTR) modulator therapy now needs to be considered, and future research needs to focus on this aspect.

Effect of experimental toothpaste containing hydroxyapatite nanoparticles and propolis, with and without fluoride, on the microcosm biofilm and enamel demineralization.

This study evaluated the antimicrobial and anticaries effects of toothpaste containing hydroxyapatite nanoparticles (nanoHAP - 5 or 10%), xylitol (2 or 3%) and propolis (1 or 2%), associated or not with 1500 ppm fluoride (F). An in vitro model was used with microcosm biofilm produced from a pool of human saliva and McBain saliva (1:50) in the first 8 h of culture on 162 bovine enamel specimens. At the end of the experimental period, analyses of metabolic activity, colony forming units (CFU) and transverse microradiography (TMR) were performed. This study showed a possible decrease in demineralization and increase in remineralization by the commercial toothpaste (1500 ppm F) and for the experimental toothpaste containing the highest concentration of all agents, combined with F. In addition, a reduction in antimicrobial activity possibly caused by propolis and xylitol, mainly in relation to cariogenic bacteria, was observed.

Evaluation of a new connected portable camera for the analysis of skin microrelief and the assessment of the effect of skin moisturisers.

BACKGROUND: Silicone replicas and non-contact methods are effective methods to analyse the micrometric scale of the skin microrelief. Yet, they imply data capture in research facilities. The capabilities of a new connected portable camera were evaluated to analyse microrelief under nomadic conditions, also studying the effect of moisturisers. MATERIALS AND METHODS: 3D depth maps were constructed using shape-from-shading algorithms. Roughness heterogeneity (Spa) was computed, and skin profiles were extracted to calculate roughness amplitude (Ra, Rq), as well as furrows/plateaus characteristics. Validation of the connected camera was performed on tanned cowhide leather and on the inner forearm skin of a single subject. The forearms of 18 subjects (23-60 years old) were also evaluated. While living their regular life, they self-performed triplicate acquisitions at various times. The effects of a placebo and of cream containing moisturisers-saccharide isomerate, urea or xylitylglucoside-anhydroxylitol-xylitol-were investigated, using untreated control skin as a reference. RESULTS: Validation of the device on leather and forearm skin shows high repeatability. The 18 subjects show the known correlation between age and changes in microrelief. While testing formulas, 8 h after a single application, all decreased Spa (-1.6/-2.1 folds). Only saccharide isomerate and xylitylglucoside-anhydroxylitol-xylitol decreased Ra (-2.4/-2.8 folds). The sectional area of plateaus was reduced from -1.5 (urea) to -2.1 folds (xylitylglucoside-anhydroxylitol-xylitol). The height of plateaus is also decreased by all moisturisers, from -1.5 (urea) to -2.1 folds (xylitylglucoside-anhydroxylitol-xylitol). CONCLUSION: This novel camera device enables microrelief analysis under nomadic conditions, allowing monitoring its changes along the day and upon moisturisers' application.

Construction of a xylose metabolic pathway in Trichosporonoides oedocephalis ATCC 16958 for the production of erythritol and xylitol.

PURPOSE: Erythritol is a valuable compound as sweetener and chemical material however cannot be fermented from the abundant substrate xylose. METHODS: The strain Trichosporonoides oedocephalis ATCC 16958 was employed to produce polyols including xylitol and erythritol by metabolic engineering approaches. RESULTS: The introduction of a substrate-specific ribose-5-phosphate isomerase endowed T. oedocephalis with xylose-assimilation activity to produce xylitol, and eliminated glycerol production simultaneously. A more value-added product, erythritol was produced by further introducing a homologous xylulose kinase. The carbon flux was redirected from xylitol to erythritol by adding high osmotic pressure. The production of erythritol was improved to 46.5 g/L in flasks by fermentation adjustment, and the process was scaled up in a 5-L fermentor, with a 40 g/L erythritol production after 120 h, and a time-space yield of 0.56 g/L/h. CONCLUSION: This study demonstrated the potential of T. oedocephalis in the synthesis of multiple useful products from xylose.

A dentifrice containing salivary enzymes and xylitol exhibits superior antimicrobial activity in vitro against adherent Streptococcus mutans compared to a chlorhexidine dentifrice.

Human saliva contains natural antimicrobial enzymes. In this in-vitro study, we evaluate the antimicrobial activity of a dentifrice containing a salivary enzyme complex (SEC) with xylitol versus a standard 0.12% chlorhexidine (CHX) dentifrice. Adherent cells of Streptococcus gordonii, Strep. mutans, Actinomyces naeslundii, Fusobacterium nucleatum subsp polymorphum, and Corynebacterium matruchotii were exposed to SEC-xylitol and CHX dentifrices for 2 min and viable CFUs were enumerated. Exposure to the SEC-xylitol dentifrice resulted in a significant reduction in bacterial viability, which was greater than that shown by the CHX dentifrice, against all organisms tested. The SEC-xylitol dentifrice also exhibited greater antimicrobial activity against all organsims in well diffusion assays compared to CHX. Dentifrice activity was also evaluated against a three species community of Strep. gordonii, Strep. mutans, and Coryne. matruchotii using bacterial live/dead stain. The SEC-xylitol dentifrice was at least as effective as CHX in removal of the multispecies community. The combination of SEC and xylitol generates a highly effective antimicrobial dentifrice with greater antibacterial activity than a standard 0.12% CHX formulations. SEC and xylitol combinations are worthy of further investigation for routine use and in the management of gingivitis and periodontal disease.