Richard Cannon | University of Otago (original) (raw)

Papers by Richard Cannon

Journal of Fungi

Fusarium keratoplasticum is the Fusarium species most commonly associated with human infections (... more Fusarium keratoplasticum is the Fusarium species most commonly associated with human infections (fusariosis). Antifungal treatment of fusariosis is often hampered by limited treatment options due to resistance towards azole antifungals. The mechanisms of antifungal resistance and sterol biosynthesis in fusaria are poorly understood. Therefore, in this study we assessed the transcriptional response of F. keratoplasticum when exposed to voriconazole. Our results revealed a group of dramatically upregulated ergosterol biosynthesis gene duplicates, most notably erg6A (912-fold), cyp51A (52-fold) and ebp1 (20-fold), which are likely part of an alternative ergosterol biosynthesis salvage pathway. The presence of human cholesterol biosynthesis gene homologs in F. keratoplasticum (ebp1, dhcr7 and dhcr24_1, dhcr24_2 and dhcr24_3) suggests that additional sterol biosynthesis pathways may be induced in fusaria under other growth conditions or during host invasion. Voriconazole also induced the...

Advanced Materials, 2022

The regeneration of diabetic bone defects remains challenging as the innate healing process is im... more The regeneration of diabetic bone defects remains challenging as the innate healing process is impaired by glucose fluctuation, reactive oxygen species (ROS), and overexpression of proteinases (such as matrix metalloproteinases, MMPs). A “diagnostic” and therapeutic dual‐logic‐based hydrogel for diabetic bone regeneration is therefore developed through the design of a double‐network hydrogel consisting of phenylboronic‐acid‐crosslinked poly(vinyl alcohol) and gelatin colloids. It exhibits a “diagnostic” logic to interpret pathological cues (glucose fluctuation, ROS, MMPs) and determines when to release drug in a diabetic microenvironment and a therapeutic logic to program different cargo release to match immune‐osteo cascade for better tissue regeneration. The hydrogel is also shown to be mechanically adaptable to the local complexity at the bone defect. Furthermore, the underlying therapeutic mechanism is elucidated, whereby the logic‐based cargo release enables the regulation of m...

Oral Surgery, Oral Medicine, Oral Pathology and Oral Radiology, 2021

Background Populations are aging worldwide, and older people are more likely to take medications ... more Background Populations are aging worldwide, and older people are more likely to take medications and undergo treatment leading to side effects such as salivary gland hypofunction. It is not known how reduced salivary flow in older people affects the Candida albicans strains colonizing the oral cavity. The presence of resistant Candida strains could be debilitating for immunocompromised older people. Objective The aim of this study was to compare C. albicans strains colonizing the mouths of older people with low and normal salivary flow. Methods Participants aged 65 and above (n = 50) were examined, and their salivary flow rates (SFRs) were determined. Swabs and smears of the palate and tongue and saliva samples were collected. Smear products were stained with periodic acid-Schiff (PAS). Yeasts were cultured, quantified, and presumptively identified using CHROMagar Candida agar. Multilocus sequence typing was used to compare C. albicans strains. Results Twenty-four participants had a...

Journal of Breath Research, 2019

Orthodontic braces can impede oral hygiene and promote halitosis. The aim of the study was to inv... more Orthodontic braces can impede oral hygiene and promote halitosis. The aim of the study was to investigate the effect of the oral probiotic Streptococcus salivarius M18 on oral hygiene indices and halitosis in patients wearing orthodontic braces. The study was a prospective, randomized, triple-blind, placebo-controlled trial. Patients undergoing fixed orthodontic treatment were randomly allocated to a probiotic group (n = 32) and a placebo group (n = 32). Patients consumed 2 lozenges d-1 for one month. Assessments were taken at baseline, at the end of the intervention, and at a 3 month follow-up. The outcome measures were plaque index (PI), gingival index (GI) and halitosis-causing volatile sulfur compound (VSC) levels. The dental biofilms before and after the intervention were analyzed utilizing next-generation sequencing of bacterial 16S rRNA genes. PI and GI scores were not significantly influenced by the probiotic intervention (intervention × time: p > 0.05). The level of VSCs decreased significantly in both the probiotic group (VSC reduction = -8.5%, 95%CI = -7.4% to -9.1%, p = 0.015) and the placebo group (-6.5%, 95%CI = -6.0% to -7.4%, p = 0.039) after 1 month intervention. However, at the 3 month follow-up, the VSC levels in the placebo group returned to baseline levels whereas those in the probiotic group decreased further (-10.8%, 95%CI = -10.5% to -12.9%, p = 0.005). Time, but not treatment, was associated with the decrease in microbial community alpha diversity and a modest effect on beta diversity. Oral probiotic S. salivarius M18 reduced the level of halitosis in patients with orthodontic braces, but had minimal effects on PI, GI and dental biofilm microflora.

Research Square (Research Square), Feb 6, 2023

The healing of infected bone defects (IBD) is a complex physiological process involving a series ... more The healing of infected bone defects (IBD) is a complex physiological process involving a series of spatially and temporally overlapping events, including pathogen clearance, immunological modulation, vascularization and osteogenesis. Based on the theory that bone healing is regulated by both biochemical and biophysical signals, in this study, we developed a copper doped bioglass (CuBGs)/methacryloyl-modi ed gelatin nanoparticle (MA-GNPs)/methacrylated silk broin (SilMA) hybrid hydrogel to promote IBD healing. This hybrid hydrogel demonstrated a dual-photocrosslinked interpenetrating network mechanism, wherein the photocrosslinked SilMA as the main network ensured structural integrity, and the photocrosslinked MA-GNPs colloidal network increased strength and dissipated loading forces. In an IBD model, the hydrogel exhibited excellent biophysical characteristics, such as adhesion, adaptation to irregular defect shapes, and in situ physical reinforcement. At the same time, by sequentially releasing biological biomimetic signals such as Cu 2+ , Ca 2+ , and Si 2+ ions from CuBGs on demand, the hydrogel spatiotemporally coordinated antibacterial, immunomodulatory and bone remodeling events, e ciently removing infection and accelerating bone repair without the use of antibiotics or exogenous recombinant proteins. Therefore, the hybrid hydrogel can be used as a simple and effective method for the treatment of IBD.

Frontiers in Nutrition, Jul 11, 2022

BMJ Open, Nov 1, 2022

Introduction Oral health is a fundamental component of well-being, and is closely associated with... more Introduction Oral health is a fundamental component of well-being, and is closely associated with overall health and quality of life. Oral health may also affect the next generation. The children of mothers with poor oral health are likely to also have poor oral health as they go through life. We aim to investigate associations between maternal oral health and general health, pregnancy outcomes, offspring oral health and offspring general health. Methods and analysis The Lifetime Impact of Oral Health study is a prospective, observational cohort study being done at a single centre in Chongqing, China. A total of 1000 pregnant women will be recruited in their first trimester (11-14 weeks gestation). After obtaining informed consent, general and oral health assessments will be undertaken. Maternal lifestyle, demographic data and biospecimens (blood, hair, urine, nail clippings, saliva, dental plaque, buccal, vaginal and anal swabs) will be collected. Pregnancy outcomes will be recorded at the time of delivery. Cord blood and placenta samples will be collected. The offspring will be followed up for general and oral health examinations, neurodevelopmental assessments and biospecimen (dental plaque, saliva, buccal swabs, exfoliated primary dentition, urine, hair, nail clippings) collection until they are 15 years old. Biological samples will undergo comprehensive metabolomic, microbiome and epigenome analyses. Associations between maternal oral health and general health, pregnancy outcomes, offspring oral health and offspring general health will be investigated and the underlying mechanisms explored. Ethics and dissemination This project has been approved by the Research Ethics Committee of the Affiliated Hospital of Stomatology of Chongqing Medical University (CQHS-REC-2021 LSNo.23). Participants will be required to provide informed consent to participate in the study. Dissemination of findings will take the form of publications in peer-reviewed journals and presentations at national and international conferences. Trial registration number ChiCTR2100046898.

Frontiers in Nutrition, Jul 11, 2022

Frontiers in Pharmacology

In the last decade, immune checkpoint blockade (ICB) has revolutionized the standard of treatment... more In the last decade, immune checkpoint blockade (ICB) has revolutionized the standard of treatment for solid tumors. Despite success in several immunogenic tumor types evidenced by improved survival, ICB remains largely unresponsive, especially in “cold tumors” with poor lymphocyte infiltration. In addition, side effects such as immune-related adverse events (irAEs) are also obstacles for the clinical translation of ICB. Recent studies have shown that focused ultrasound (FUS), a non-invasive technology proven to be effective and safe for tumor treatment in clinical settings, could boost the therapeutic effect of ICB while alleviating the potential side effects. Most importantly, the application of FUS to ultrasound-sensitive small particles, such as microbubbles (MBs) or nanoparticles (NPs), allows for precise delivery and release of genetic materials, catalysts and chemotherapeutic agents to tumor sites, thus enhancing the anti-tumor effects of ICB while minimizing toxicity. In this...

Frontiers in Pharmacology

In the last decade, immune checkpoint blockade (ICB) has revolutionized the standard of treatment... more In the last decade, immune checkpoint blockade (ICB) has revolutionized the standard of treatment for solid tumors. Despite success in several immunogenic tumor types evidenced by improved survival, ICB remains largely unresponsive, especially in “cold tumors” with poor lymphocyte infiltration. In addition, side effects such as immune-related adverse events (irAEs) are also obstacles for the clinical translation of ICB. Recent studies have shown that focused ultrasound (FUS), a non-invasive technology proven to be effective and safe for tumor treatment in clinical settings, could boost the therapeutic effect of ICB while alleviating the potential side effects. Most importantly, the application of FUS to ultrasound-sensitive small particles, such as microbubbles (MBs) or nanoparticles (NPs), allows for precise delivery and release of genetic materials, catalysts and chemotherapeutic agents to tumor sites, thus enhancing the anti-tumor effects of ICB while minimizing toxicity. In this...

Orthodontics & Craniofacial Research, 2021

BackgroundMany modifications to fixed orthodontic appliances have been introduced to manage biofi... more BackgroundMany modifications to fixed orthodontic appliances have been introduced to manage biofilm formation. The aim of this review was to investigate elastomeric ligation in comparison with stainless steel ligation and self‐ligation with regard to microbiological and clinical indicators of biofilm formation in patients wearing multi‐bracketed fixed orthodontic appliances.MethodsThe MEDLINE and the EMBASE databases were searched up to February 2021 and supplemented by additional manual searches of bibliographies. Parallel‐group and split‐mouth randomized controlled trials (RCTs) comparing different ligation methods were identified. The Cochrane Risk of Bias‐2 tool was applied to assess the quality of evidence.ResultsA total of 11 RCTs were included in this review. Nine RCTs compared self‐ligation and elastomeric ligation; two compared elastomeric ligation and stainless steel ligation. The included studies had either some concerns or were at a high risk of bias. Qualitative assessm...

Clinical Oral Investigations, 2021

OBJECTIVES To examine the relationship between masticatory muscle activity (MMA), self-reported o... more OBJECTIVES To examine the relationship between masticatory muscle activity (MMA), self-reported oral behaviours (OBs) and overall physical activity (PA) in adult women. MATERIALS AND METHODS MMA and PA were assessed by a wearable electromyography (EMG) device and accelerometer respectively, worn over 2 non-consecutive days by 53 women (mean age 27.5 ± 6.4 years). Following the second recording day, self-reported OBs were assessed. MMA was assessed by the number, amplitude and duration of masseter contraction episodes. Masseter muscle EMG outcome measures were number of contraction episodes per hour (CEs/h) and the relative contraction time (RCT%). PA was assessed by time accumulated in moderate to vigorous physical activity (MVPA) and 10-min bouts of MVPA per hour. Data were analysed using mixed model analysis. RESULTS MMA in free-living conditions consisted mostly of low-amplitude (<10% maximum voluntary clenching) and short-duration (<10 s) contraction episodes. Masseter CEs/h were not associated with self-reported levels of OB. Masseter CEs/h were positively associated with time accumulated in MVPA (F = 9.9; p = 0.002) and negatively associated with 10-min bouts of MVPA/h (F = 15.8; p <0.001). RCT% was not significantly associated with either. CONCLUSIONS Objectively assessed MMA is not associated with self-reported OB in free-moving adult females. Moderate to vigorous exercise and physical inactivity are accompanied with an increase in the number of masseter muscle contractions and thus possibly tooth clenching activity. CLINICAL RELEVANCE OB can be influenced by the type and extent of PA. Subjective assessment of MMA by questionnaire and/or interviews may be invalid.

PLoS ONE, 2013

Phenylethyl alcohol was one of the first quorum sensing molecules (QSMs) identified in C. albican... more Phenylethyl alcohol was one of the first quorum sensing molecules (QSMs) identified in C. albicans. This extracellular signalling molecule inhibits the hyphal formation of C. albicans at high cell density. Little is known, however, about the underlying mechanisms by which this QSM regulates the morphological switches of C. albicans. Therefore, we have applied metabolomics and isotope labelling experiments to investigate the metabolic changes that occur in C. albicans in response to phenylethyl alcohol under defined hyphae-inducing conditions. Our results showed a global upregulation of central carbon metabolism when hyphal development was suppressed by phenylethyl alcohol. By comparing the metabolic changes in response to phenylethyl alcohol to our previous metabolomic studies, we were able to shortlist 7 metabolic pathways from central carbon metabolism that appear to be associated with C. albicans morphogenesis. Furthermore, isotope-labelling data showed that phenylethyl alcohol is indeed taken up and catabolised by yeast cells. Isotope-labelled carbon atoms were found in the majority of amino acids as well as in lactate and glyoxylate. However, isotope-labelled carbon atoms from phenylethyl alcohol accumulated mainly in the pyridine ring of NAD + /NADH and NADP 2/ NADPH molecules, showing that these nucleotides were the main products of phenylethyl alcohol catabolism. Interestingly, two metabolic pathways where these nucleotides play an important role, nitrogen metabolism and nicotinate/nicotinamide metabolism, were also short-listed through our previous metabolomics works as metabolic pathways likely to be closely associated with C. albicans morphogenesis.

Frontiers in Endocrinology

BackgroundGestational diabetes mellitus (GDM) is a metabolic condition defined as glucose intoler... more BackgroundGestational diabetes mellitus (GDM) is a metabolic condition defined as glucose intolerance with first presentation during pregnancy. Many studies suggest that environmental exposures, including air pollution, contribute to the pathogenesis of GDM. Although hair metabolite profiles have been shown to reflect pollution exposure, few studies have examined the link between environmental exposures, the maternal hair metabolome and GDM. The aim of this study was to investigate the longitudinal relationship (from pre-conception through to the third trimester) between air pollution exposure, the hair metabolome and GDM in a Chinese cohort.MethodsA total of 1020 women enrolled in the Complex Lipids in Mothers and Babies (CLIMB) birth cohort were included in our study. Metabolites from maternal hair segments collected pre-conception, and in the first, second, and third trimesters were analysed using gas chromatography-mass spectrometry (GC-MS). Maternal exposure to air pollution wa...

Springer eBooks, 2017

Proteins catalysing the transport of molecules across biological membranes are vital for organism... more Proteins catalysing the transport of molecules across biological membranes are vital for organisms in all kingdoms of life. These proteins are needed for the uptake of nutrients and the efflux of signalling molecules and toxic compounds. In the human opportunistic pathogen Candida albicans, efflux proteins can translocate antifungal drugs, such as fluconazole, and confer drug resistance. There are two main families of membrane proteins involved in drug transport, the major facilitator superfamily (MFS) and the ATP-binding cassette (ABC) proteins. Both types of protein possess multiple membrane spanning α-helices in transmembrane domains (TMDs), and ABC proteins, in addition, contain cytosolic nucleotide-binding domains (NBDs) involved in ATP hydrolysis. ABC proteins, and to a lesser extent MFS proteins, have broad substrate specificities that are determined by the structure and arrangement of the transmembrane α-helices. The multidrug transporter most often associated with drug resistance of C. albicans clinical isolates is ABC protein Cdr1. This is a pleiotropic drug resistance (PDR) ABC protein with domain arrangement NBD1-TMD1-NBD2-TMD2 and unique large extracellular loops between transmembrane α-helices that may be important for pump function. There is no crystal structure for Cdr1, but X-ray structures of related proteins indicate that unique interactions between conserved elements of the TMDs and the NBDs are important for pump function.

Fems Yeast Research, Mar 15, 2013

Candida albicans is a major cause of opportunistic and life-threatening systemic fungal infection... more Candida albicans is a major cause of opportunistic and life-threatening systemic fungal infections, especially in the immunocompromised. The plasma membrane proton-pumping ATPase (Pma1p) is an essential enzyme that generates the electrochemical gradient required for cell growth. We expressed C. albicans Pma1p (CaPma1p) in Saccharomyces cerevisiae to facilitate screening for inhibitors. Replacement of S. cerevisiae PMA1 with C. albicans PMA1 gave clones expressing CaPma1p that grew slowly at low pH. CaPma1p was expressed at significantly lower levels and had lower specific activity than the native Pma1p. It also conferred pH sensitivity, hygromycin B resistance, and low levels of glucose-dependent proton pumping. Recombination between CaPMA1 and the homologous nonessential ScPMA2 resulted in chimeric suppressor mutants that expressed functional CaPma1p with improved H +-ATPase activity and growth rates at low pH. Molecular models of suppressor mutants identified specific amino acids (between 531 and 595 in CaPma1p) that may affect regulation of the activity of Pma1p oligomers in S. cerevisiae. A modified CaPma1p chimeric construct containing only 5 amino acids from ScPma2p enabled the expression of a fully functional enzyme for drug screens and structural resolution.

Journal of Visualized Experiments, Jun 13, 2021

The successful biochemical and biophysical characterization of ABC transporters depends heavily o... more The successful biochemical and biophysical characterization of ABC transporters depends heavily on the choice of the heterologous expression system. Over the past two decades, we have developed a yeast membrane protein expression platform that has been used to study many important fungal membrane proteins. The expression host Saccharomyces cerevisiae ADΔΔ is deleted in seven major endogenous ABC transporters and it contains the transcription factor Pdr1-3 with a gain-of-function mutation that enables the constitutive overexpression of heterologous membrane protein genes stably integrated as single copies at the genomic PDR5 locus. The creation of versatile plasmid vectors and the optimization of one-step cloning strategies enables the rapid and accurate cloning, mutagenesis, and expression of heterologous ABC transporters. Here, we describe the development and use of a novel protease-cleavable mGFPHis double tag (i.e., the monomeric yeast enhanced green fluorescent protein yEGFP3 fused to a six-histidine affinity purification tag) that was designed to avoid possible interference of the tag with the protein of interest and to increase the binding efficiency of the His tag to nickel-affinity resins. The fusion of mGFPHis to the membrane protein ORF (open reading frame) enables easy quantification of the protein by inspection of polyacrylamide gels and detection of degradation products retaining the mGFPHis tag. We demonstrate how this feature facilitates detergent screening for membrane protein solubilization. A protocol for the efficient, fast, and reliable isolation of the small-scale plasma membrane preparations of the C-terminally tagged Candida albicans multidrug efflux transporter Cdr1 overexpressed in S. cerevisiae ADΔΔ, is presented. This small-scale plasma membrane isolation protocol generates high-quality plasma membranes within a single working day. The plasma membrane preparations can be used to determine the enzyme activities of Cdr1 and Cdr1 mutant variants.

Oral Diseases, 2021

IntroductionEarly detection of coronavirus disease 2019 (COVID‐19) is paramount for controlling t... more IntroductionEarly detection of coronavirus disease 2019 (COVID‐19) is paramount for controlling the progression and spread of the disease. Currently, nasopharyngeal swabbing (NPS) is the standard method for collecting specimens. Saliva was recently proposed as an easy and safe option with many authorities adopting the methodology despite the limited evidence of efficacy.ObjectivesThe aim of this review was to systematically evaluate the current literature on the use of saliva test for detecting severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) and carry out a meta‐analysis to determine its diagnostic accuracy.Materials and methodsProspective studies were searched for in electronic databases, complemented by hand‐searching relevant journals. The risk of bias and applicability were assessed using the revised Quality Assessment of Studies of Diagnostic Accuracy Studies (QUADAS‐2) tool. Meta‐analyses and meta‐regression modeling were performed to calculate the diagnostic accu...

Journal of Fungi

Fusarium keratoplasticum is the Fusarium species most commonly associated with human infections (... more Fusarium keratoplasticum is the Fusarium species most commonly associated with human infections (fusariosis). Antifungal treatment of fusariosis is often hampered by limited treatment options due to resistance towards azole antifungals. The mechanisms of antifungal resistance and sterol biosynthesis in fusaria are poorly understood. Therefore, in this study we assessed the transcriptional response of F. keratoplasticum when exposed to voriconazole. Our results revealed a group of dramatically upregulated ergosterol biosynthesis gene duplicates, most notably erg6A (912-fold), cyp51A (52-fold) and ebp1 (20-fold), which are likely part of an alternative ergosterol biosynthesis salvage pathway. The presence of human cholesterol biosynthesis gene homologs in F. keratoplasticum (ebp1, dhcr7 and dhcr24_1, dhcr24_2 and dhcr24_3) suggests that additional sterol biosynthesis pathways may be induced in fusaria under other growth conditions or during host invasion. Voriconazole also induced the...

Advanced Materials, 2022

The regeneration of diabetic bone defects remains challenging as the innate healing process is im... more The regeneration of diabetic bone defects remains challenging as the innate healing process is impaired by glucose fluctuation, reactive oxygen species (ROS), and overexpression of proteinases (such as matrix metalloproteinases, MMPs). A “diagnostic” and therapeutic dual‐logic‐based hydrogel for diabetic bone regeneration is therefore developed through the design of a double‐network hydrogel consisting of phenylboronic‐acid‐crosslinked poly(vinyl alcohol) and gelatin colloids. It exhibits a “diagnostic” logic to interpret pathological cues (glucose fluctuation, ROS, MMPs) and determines when to release drug in a diabetic microenvironment and a therapeutic logic to program different cargo release to match immune‐osteo cascade for better tissue regeneration. The hydrogel is also shown to be mechanically adaptable to the local complexity at the bone defect. Furthermore, the underlying therapeutic mechanism is elucidated, whereby the logic‐based cargo release enables the regulation of m...

Oral Surgery, Oral Medicine, Oral Pathology and Oral Radiology, 2021

Background Populations are aging worldwide, and older people are more likely to take medications ... more Background Populations are aging worldwide, and older people are more likely to take medications and undergo treatment leading to side effects such as salivary gland hypofunction. It is not known how reduced salivary flow in older people affects the Candida albicans strains colonizing the oral cavity. The presence of resistant Candida strains could be debilitating for immunocompromised older people. Objective The aim of this study was to compare C. albicans strains colonizing the mouths of older people with low and normal salivary flow. Methods Participants aged 65 and above (n = 50) were examined, and their salivary flow rates (SFRs) were determined. Swabs and smears of the palate and tongue and saliva samples were collected. Smear products were stained with periodic acid-Schiff (PAS). Yeasts were cultured, quantified, and presumptively identified using CHROMagar Candida agar. Multilocus sequence typing was used to compare C. albicans strains. Results Twenty-four participants had a...

Journal of Breath Research, 2019

Orthodontic braces can impede oral hygiene and promote halitosis. The aim of the study was to inv... more Orthodontic braces can impede oral hygiene and promote halitosis. The aim of the study was to investigate the effect of the oral probiotic Streptococcus salivarius M18 on oral hygiene indices and halitosis in patients wearing orthodontic braces. The study was a prospective, randomized, triple-blind, placebo-controlled trial. Patients undergoing fixed orthodontic treatment were randomly allocated to a probiotic group (n = 32) and a placebo group (n = 32). Patients consumed 2 lozenges d-1 for one month. Assessments were taken at baseline, at the end of the intervention, and at a 3 month follow-up. The outcome measures were plaque index (PI), gingival index (GI) and halitosis-causing volatile sulfur compound (VSC) levels. The dental biofilms before and after the intervention were analyzed utilizing next-generation sequencing of bacterial 16S rRNA genes. PI and GI scores were not significantly influenced by the probiotic intervention (intervention × time: p > 0.05). The level of VSCs decreased significantly in both the probiotic group (VSC reduction = -8.5%, 95%CI = -7.4% to -9.1%, p = 0.015) and the placebo group (-6.5%, 95%CI = -6.0% to -7.4%, p = 0.039) after 1 month intervention. However, at the 3 month follow-up, the VSC levels in the placebo group returned to baseline levels whereas those in the probiotic group decreased further (-10.8%, 95%CI = -10.5% to -12.9%, p = 0.005). Time, but not treatment, was associated with the decrease in microbial community alpha diversity and a modest effect on beta diversity. Oral probiotic S. salivarius M18 reduced the level of halitosis in patients with orthodontic braces, but had minimal effects on PI, GI and dental biofilm microflora.

Research Square (Research Square), Feb 6, 2023

The healing of infected bone defects (IBD) is a complex physiological process involving a series ... more The healing of infected bone defects (IBD) is a complex physiological process involving a series of spatially and temporally overlapping events, including pathogen clearance, immunological modulation, vascularization and osteogenesis. Based on the theory that bone healing is regulated by both biochemical and biophysical signals, in this study, we developed a copper doped bioglass (CuBGs)/methacryloyl-modi ed gelatin nanoparticle (MA-GNPs)/methacrylated silk broin (SilMA) hybrid hydrogel to promote IBD healing. This hybrid hydrogel demonstrated a dual-photocrosslinked interpenetrating network mechanism, wherein the photocrosslinked SilMA as the main network ensured structural integrity, and the photocrosslinked MA-GNPs colloidal network increased strength and dissipated loading forces. In an IBD model, the hydrogel exhibited excellent biophysical characteristics, such as adhesion, adaptation to irregular defect shapes, and in situ physical reinforcement. At the same time, by sequentially releasing biological biomimetic signals such as Cu 2+ , Ca 2+ , and Si 2+ ions from CuBGs on demand, the hydrogel spatiotemporally coordinated antibacterial, immunomodulatory and bone remodeling events, e ciently removing infection and accelerating bone repair without the use of antibiotics or exogenous recombinant proteins. Therefore, the hybrid hydrogel can be used as a simple and effective method for the treatment of IBD.

Frontiers in Nutrition, Jul 11, 2022

BMJ Open, Nov 1, 2022

Introduction Oral health is a fundamental component of well-being, and is closely associated with... more Introduction Oral health is a fundamental component of well-being, and is closely associated with overall health and quality of life. Oral health may also affect the next generation. The children of mothers with poor oral health are likely to also have poor oral health as they go through life. We aim to investigate associations between maternal oral health and general health, pregnancy outcomes, offspring oral health and offspring general health. Methods and analysis The Lifetime Impact of Oral Health study is a prospective, observational cohort study being done at a single centre in Chongqing, China. A total of 1000 pregnant women will be recruited in their first trimester (11-14 weeks gestation). After obtaining informed consent, general and oral health assessments will be undertaken. Maternal lifestyle, demographic data and biospecimens (blood, hair, urine, nail clippings, saliva, dental plaque, buccal, vaginal and anal swabs) will be collected. Pregnancy outcomes will be recorded at the time of delivery. Cord blood and placenta samples will be collected. The offspring will be followed up for general and oral health examinations, neurodevelopmental assessments and biospecimen (dental plaque, saliva, buccal swabs, exfoliated primary dentition, urine, hair, nail clippings) collection until they are 15 years old. Biological samples will undergo comprehensive metabolomic, microbiome and epigenome analyses. Associations between maternal oral health and general health, pregnancy outcomes, offspring oral health and offspring general health will be investigated and the underlying mechanisms explored. Ethics and dissemination This project has been approved by the Research Ethics Committee of the Affiliated Hospital of Stomatology of Chongqing Medical University (CQHS-REC-2021 LSNo.23). Participants will be required to provide informed consent to participate in the study. Dissemination of findings will take the form of publications in peer-reviewed journals and presentations at national and international conferences. Trial registration number ChiCTR2100046898.

Frontiers in Nutrition, Jul 11, 2022

Frontiers in Pharmacology

In the last decade, immune checkpoint blockade (ICB) has revolutionized the standard of treatment... more In the last decade, immune checkpoint blockade (ICB) has revolutionized the standard of treatment for solid tumors. Despite success in several immunogenic tumor types evidenced by improved survival, ICB remains largely unresponsive, especially in “cold tumors” with poor lymphocyte infiltration. In addition, side effects such as immune-related adverse events (irAEs) are also obstacles for the clinical translation of ICB. Recent studies have shown that focused ultrasound (FUS), a non-invasive technology proven to be effective and safe for tumor treatment in clinical settings, could boost the therapeutic effect of ICB while alleviating the potential side effects. Most importantly, the application of FUS to ultrasound-sensitive small particles, such as microbubbles (MBs) or nanoparticles (NPs), allows for precise delivery and release of genetic materials, catalysts and chemotherapeutic agents to tumor sites, thus enhancing the anti-tumor effects of ICB while minimizing toxicity. In this...

Frontiers in Pharmacology

In the last decade, immune checkpoint blockade (ICB) has revolutionized the standard of treatment... more In the last decade, immune checkpoint blockade (ICB) has revolutionized the standard of treatment for solid tumors. Despite success in several immunogenic tumor types evidenced by improved survival, ICB remains largely unresponsive, especially in “cold tumors” with poor lymphocyte infiltration. In addition, side effects such as immune-related adverse events (irAEs) are also obstacles for the clinical translation of ICB. Recent studies have shown that focused ultrasound (FUS), a non-invasive technology proven to be effective and safe for tumor treatment in clinical settings, could boost the therapeutic effect of ICB while alleviating the potential side effects. Most importantly, the application of FUS to ultrasound-sensitive small particles, such as microbubbles (MBs) or nanoparticles (NPs), allows for precise delivery and release of genetic materials, catalysts and chemotherapeutic agents to tumor sites, thus enhancing the anti-tumor effects of ICB while minimizing toxicity. In this...

Orthodontics & Craniofacial Research, 2021

BackgroundMany modifications to fixed orthodontic appliances have been introduced to manage biofi... more BackgroundMany modifications to fixed orthodontic appliances have been introduced to manage biofilm formation. The aim of this review was to investigate elastomeric ligation in comparison with stainless steel ligation and self‐ligation with regard to microbiological and clinical indicators of biofilm formation in patients wearing multi‐bracketed fixed orthodontic appliances.MethodsThe MEDLINE and the EMBASE databases were searched up to February 2021 and supplemented by additional manual searches of bibliographies. Parallel‐group and split‐mouth randomized controlled trials (RCTs) comparing different ligation methods were identified. The Cochrane Risk of Bias‐2 tool was applied to assess the quality of evidence.ResultsA total of 11 RCTs were included in this review. Nine RCTs compared self‐ligation and elastomeric ligation; two compared elastomeric ligation and stainless steel ligation. The included studies had either some concerns or were at a high risk of bias. Qualitative assessm...

Clinical Oral Investigations, 2021

OBJECTIVES To examine the relationship between masticatory muscle activity (MMA), self-reported o... more OBJECTIVES To examine the relationship between masticatory muscle activity (MMA), self-reported oral behaviours (OBs) and overall physical activity (PA) in adult women. MATERIALS AND METHODS MMA and PA were assessed by a wearable electromyography (EMG) device and accelerometer respectively, worn over 2 non-consecutive days by 53 women (mean age 27.5 ± 6.4 years). Following the second recording day, self-reported OBs were assessed. MMA was assessed by the number, amplitude and duration of masseter contraction episodes. Masseter muscle EMG outcome measures were number of contraction episodes per hour (CEs/h) and the relative contraction time (RCT%). PA was assessed by time accumulated in moderate to vigorous physical activity (MVPA) and 10-min bouts of MVPA per hour. Data were analysed using mixed model analysis. RESULTS MMA in free-living conditions consisted mostly of low-amplitude (<10% maximum voluntary clenching) and short-duration (<10 s) contraction episodes. Masseter CEs/h were not associated with self-reported levels of OB. Masseter CEs/h were positively associated with time accumulated in MVPA (F = 9.9; p = 0.002) and negatively associated with 10-min bouts of MVPA/h (F = 15.8; p <0.001). RCT% was not significantly associated with either. CONCLUSIONS Objectively assessed MMA is not associated with self-reported OB in free-moving adult females. Moderate to vigorous exercise and physical inactivity are accompanied with an increase in the number of masseter muscle contractions and thus possibly tooth clenching activity. CLINICAL RELEVANCE OB can be influenced by the type and extent of PA. Subjective assessment of MMA by questionnaire and/or interviews may be invalid.

PLoS ONE, 2013

Phenylethyl alcohol was one of the first quorum sensing molecules (QSMs) identified in C. albican... more Phenylethyl alcohol was one of the first quorum sensing molecules (QSMs) identified in C. albicans. This extracellular signalling molecule inhibits the hyphal formation of C. albicans at high cell density. Little is known, however, about the underlying mechanisms by which this QSM regulates the morphological switches of C. albicans. Therefore, we have applied metabolomics and isotope labelling experiments to investigate the metabolic changes that occur in C. albicans in response to phenylethyl alcohol under defined hyphae-inducing conditions. Our results showed a global upregulation of central carbon metabolism when hyphal development was suppressed by phenylethyl alcohol. By comparing the metabolic changes in response to phenylethyl alcohol to our previous metabolomic studies, we were able to shortlist 7 metabolic pathways from central carbon metabolism that appear to be associated with C. albicans morphogenesis. Furthermore, isotope-labelling data showed that phenylethyl alcohol is indeed taken up and catabolised by yeast cells. Isotope-labelled carbon atoms were found in the majority of amino acids as well as in lactate and glyoxylate. However, isotope-labelled carbon atoms from phenylethyl alcohol accumulated mainly in the pyridine ring of NAD + /NADH and NADP 2/ NADPH molecules, showing that these nucleotides were the main products of phenylethyl alcohol catabolism. Interestingly, two metabolic pathways where these nucleotides play an important role, nitrogen metabolism and nicotinate/nicotinamide metabolism, were also short-listed through our previous metabolomics works as metabolic pathways likely to be closely associated with C. albicans morphogenesis.

Frontiers in Endocrinology

BackgroundGestational diabetes mellitus (GDM) is a metabolic condition defined as glucose intoler... more BackgroundGestational diabetes mellitus (GDM) is a metabolic condition defined as glucose intolerance with first presentation during pregnancy. Many studies suggest that environmental exposures, including air pollution, contribute to the pathogenesis of GDM. Although hair metabolite profiles have been shown to reflect pollution exposure, few studies have examined the link between environmental exposures, the maternal hair metabolome and GDM. The aim of this study was to investigate the longitudinal relationship (from pre-conception through to the third trimester) between air pollution exposure, the hair metabolome and GDM in a Chinese cohort.MethodsA total of 1020 women enrolled in the Complex Lipids in Mothers and Babies (CLIMB) birth cohort were included in our study. Metabolites from maternal hair segments collected pre-conception, and in the first, second, and third trimesters were analysed using gas chromatography-mass spectrometry (GC-MS). Maternal exposure to air pollution wa...

Springer eBooks, 2017

Proteins catalysing the transport of molecules across biological membranes are vital for organism... more Proteins catalysing the transport of molecules across biological membranes are vital for organisms in all kingdoms of life. These proteins are needed for the uptake of nutrients and the efflux of signalling molecules and toxic compounds. In the human opportunistic pathogen Candida albicans, efflux proteins can translocate antifungal drugs, such as fluconazole, and confer drug resistance. There are two main families of membrane proteins involved in drug transport, the major facilitator superfamily (MFS) and the ATP-binding cassette (ABC) proteins. Both types of protein possess multiple membrane spanning α-helices in transmembrane domains (TMDs), and ABC proteins, in addition, contain cytosolic nucleotide-binding domains (NBDs) involved in ATP hydrolysis. ABC proteins, and to a lesser extent MFS proteins, have broad substrate specificities that are determined by the structure and arrangement of the transmembrane α-helices. The multidrug transporter most often associated with drug resistance of C. albicans clinical isolates is ABC protein Cdr1. This is a pleiotropic drug resistance (PDR) ABC protein with domain arrangement NBD1-TMD1-NBD2-TMD2 and unique large extracellular loops between transmembrane α-helices that may be important for pump function. There is no crystal structure for Cdr1, but X-ray structures of related proteins indicate that unique interactions between conserved elements of the TMDs and the NBDs are important for pump function.

Fems Yeast Research, Mar 15, 2013

Candida albicans is a major cause of opportunistic and life-threatening systemic fungal infection... more Candida albicans is a major cause of opportunistic and life-threatening systemic fungal infections, especially in the immunocompromised. The plasma membrane proton-pumping ATPase (Pma1p) is an essential enzyme that generates the electrochemical gradient required for cell growth. We expressed C. albicans Pma1p (CaPma1p) in Saccharomyces cerevisiae to facilitate screening for inhibitors. Replacement of S. cerevisiae PMA1 with C. albicans PMA1 gave clones expressing CaPma1p that grew slowly at low pH. CaPma1p was expressed at significantly lower levels and had lower specific activity than the native Pma1p. It also conferred pH sensitivity, hygromycin B resistance, and low levels of glucose-dependent proton pumping. Recombination between CaPMA1 and the homologous nonessential ScPMA2 resulted in chimeric suppressor mutants that expressed functional CaPma1p with improved H +-ATPase activity and growth rates at low pH. Molecular models of suppressor mutants identified specific amino acids (between 531 and 595 in CaPma1p) that may affect regulation of the activity of Pma1p oligomers in S. cerevisiae. A modified CaPma1p chimeric construct containing only 5 amino acids from ScPma2p enabled the expression of a fully functional enzyme for drug screens and structural resolution.

Journal of Visualized Experiments, Jun 13, 2021

The successful biochemical and biophysical characterization of ABC transporters depends heavily o... more The successful biochemical and biophysical characterization of ABC transporters depends heavily on the choice of the heterologous expression system. Over the past two decades, we have developed a yeast membrane protein expression platform that has been used to study many important fungal membrane proteins. The expression host Saccharomyces cerevisiae ADΔΔ is deleted in seven major endogenous ABC transporters and it contains the transcription factor Pdr1-3 with a gain-of-function mutation that enables the constitutive overexpression of heterologous membrane protein genes stably integrated as single copies at the genomic PDR5 locus. The creation of versatile plasmid vectors and the optimization of one-step cloning strategies enables the rapid and accurate cloning, mutagenesis, and expression of heterologous ABC transporters. Here, we describe the development and use of a novel protease-cleavable mGFPHis double tag (i.e., the monomeric yeast enhanced green fluorescent protein yEGFP3 fused to a six-histidine affinity purification tag) that was designed to avoid possible interference of the tag with the protein of interest and to increase the binding efficiency of the His tag to nickel-affinity resins. The fusion of mGFPHis to the membrane protein ORF (open reading frame) enables easy quantification of the protein by inspection of polyacrylamide gels and detection of degradation products retaining the mGFPHis tag. We demonstrate how this feature facilitates detergent screening for membrane protein solubilization. A protocol for the efficient, fast, and reliable isolation of the small-scale plasma membrane preparations of the C-terminally tagged Candida albicans multidrug efflux transporter Cdr1 overexpressed in S. cerevisiae ADΔΔ, is presented. This small-scale plasma membrane isolation protocol generates high-quality plasma membranes within a single working day. The plasma membrane preparations can be used to determine the enzyme activities of Cdr1 and Cdr1 mutant variants.

Oral Diseases, 2021

IntroductionEarly detection of coronavirus disease 2019 (COVID‐19) is paramount for controlling t... more IntroductionEarly detection of coronavirus disease 2019 (COVID‐19) is paramount for controlling the progression and spread of the disease. Currently, nasopharyngeal swabbing (NPS) is the standard method for collecting specimens. Saliva was recently proposed as an easy and safe option with many authorities adopting the methodology despite the limited evidence of efficacy.ObjectivesThe aim of this review was to systematically evaluate the current literature on the use of saliva test for detecting severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) and carry out a meta‐analysis to determine its diagnostic accuracy.Materials and methodsProspective studies were searched for in electronic databases, complemented by hand‐searching relevant journals. The risk of bias and applicability were assessed using the revised Quality Assessment of Studies of Diagnostic Accuracy Studies (QUADAS‐2) tool. Meta‐analyses and meta‐regression modeling were performed to calculate the diagnostic accu...