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1.
Ecol Appl ; 31(8): e02451, 2021 12.
Article in English | MEDLINE | ID: mdl-34519125

ABSTRACT

In tropical forests, the high proportion of trees showing irregularities at the stem base complicates forest monitoring. For example, in the presence of buttresses, the height of the point of measurement (HPOM ) of the stem diameter (DPOM ) is raised from 1.3 m, the standard breast height, up to a regular part of the stem. While DPOM is the most important predictor for tree aboveground biomass (AGB) estimates, the lack of harmonized HPOM for irregular trees in forest inventory increases the uncertainty in plot-level AGB stock and stock change estimates. In this study, we gathered an original non-destructive three-dimensional (3D) data set collected with terrestrial laser scanning and close range terrestrial photogrammetry tools in three sites in central Africa. For the 228 irregularly shaped stems sampled, we developed a set of taper models to harmonize HPOM by predicting the equivalent diameter at breast height (DBH') from a DPOM measured at any height. We analyzed the effect of using DBH' on tree-level and plot-level AGB estimates. To do so, we used destructive AGB data for 140 trees and forest inventory data from eight 1-ha plots in the Republic of Congo. Our results showed that our best simple taper model predicts DBH' with a relative mean absolute error of 3.7% (R2 = 0.98) over a wide DPOM range of 17-249 cm. Based on destructive AGB data, we found that the AGB allometric model calibrated with harmonized HPOM data was more accurate than the conventional local and pantropical models. At the plot level, the comparison of AGB stock estimates with and without HPOM harmonization showed an increasing divergence with the increasing share of irregular stems (up to -15%). The harmonization procedure developed in this study could be implemented as a standard practice for AGB monitoring in tropical forests as no additional forest inventory measurements is required. This would probably lead to important revisions of the AGB stock estimates in regions having a large number of irregular tree stems and increase their carbon sink estimates. The growing use of three-dimensional (3D) data offers new opportunities to extend our approach and further develop general taper models in other tropical regions.


Subject(s)
Trees , Tropical Climate , Biomass , Carbon Sequestration , Forests
2.
J Neurol ; 265(10): 2251-2259, 2018 Oct.
Article in English | MEDLINE | ID: mdl-30054790

ABSTRACT

BACKGROUND: Tumefactive demyelinating lesions of the central nervous system can be the initial presentation in various pathological entities [multiple sclerosis (the most common), Balo's concentric sclerosis, Schilder's disease and acute disseminated encephalomyelitis] with overlapping clinical presentation. The aim of our study was to better characterize these patients. METHODS: Eighty-seven patients (62 women and 25 men) from different MS centers in France were studied retrospectively. Inclusion criteria were (1) a first clinical event (2) MRI showing one or more large demyelinating lesions (20 mm or more in diameter) with mass-like features. Patients with a previous demyelinating event (i.e. confirmed multiple sclerosis) were excluded. RESULTS: Mean age at onset was 26 years. The most common initial symptoms (67% of the patients) were hemiparesis or hemiplegia. Aphasia, headache and cognitive disturbances (i.e. atypical symptoms for demyelinating diseases) were observed in 15, 18 and 15% of patients, respectively. The mean largest diameter of the tumefactive lesions was 26.9 mm, with gadolinium enhancement in 66 patients (81%). Twenty-one patients (24%) had a single tumefactive lesion. During follow-up (median time 5.7 years) 4 patients died, 70 patients improved or remained stable and 12 worsened. 86% of patients received initial corticosteroid treatment, and 73% received disease-modifying therapy subsequently. EDSS at the end of the follow-up was 2.4 ± 2.6 (mean ± SD). CONCLUSION: This study provides further evidence that the clinical course of MS presenting with large focal tumor-like lesions does not differ from that of classical relapsing-remitting MS, once the noisy first relapsing occurred.


Subject(s)
Multiple Sclerosis/diagnostic imaging , Adult , Brain/diagnostic imaging , Diffuse Cerebral Sclerosis of Schilder/diagnostic imaging , Disease Progression , Female , Follow-Up Studies , Humans , Magnetic Resonance Imaging , Male , Multiple Sclerosis/pathology , Multiple Sclerosis/therapy , Retrospective Studies
3.
Oncogene ; 37(4): 512-521, 2018 01 25.
Article in English | MEDLINE | ID: mdl-28991225

ABSTRACT

Metabolic changes are linked to epigenetic reprogramming and play important roles in several tumor types. PGC-1α is a transcriptional coactivator controlling mitochondrial biogenesis and is linked to oxidative phosphorylation. We provide evidence that melanoma models with elevated PGC-1α levels are characteristic of the proliferative phenotype and are sensitive to bromodomain and extra-terminal domain (BET) inhibitor treatment. A super-enhancer region highly occupied by the BET family member BRD4 was identified for the PGC-1α gene. BET inhibitor treatment prevented this interaction, leading to a dramatic reduction of PGC-1α expression. Accordingly, BET inhibition diminished respiration and mitochondrial function in cells. In vivo, melanoma models with high PGC-1α expression strongly responded to BET inhibition by reduction of PGC-1α and impaired tumor growth. Altogether, our findings identify epigenetic regulatory elements that define a subset of melanomas with high sensitivity to BET inhibition, which opens up the opportunity to define melanoma patients most likely to respond to this treatment, depending on their tumor characteristics.


Subject(s)
Antineoplastic Agents/pharmacology , Enhancer Elements, Genetic/genetics , Melanoma/genetics , Nuclear Proteins/antagonists & inhibitors , Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha/genetics , Transcription Factors/antagonists & inhibitors , Animals , Antineoplastic Agents/therapeutic use , Azepines/pharmacology , Azepines/therapeutic use , Benzodiazepines/pharmacology , Benzodiazepines/therapeutic use , Cell Cycle Proteins , Cell Line, Tumor , Cell Proliferation/drug effects , Cell Proliferation/genetics , Drug Resistance, Neoplasm/genetics , Epigenesis, Genetic , Female , Gene Expression Profiling , Gene Expression Regulation, Neoplastic , Humans , Melanoma/drug therapy , Melanoma/pathology , Mice , Mice, Inbred C57BL , Mice, Nude , Mitochondria/drug effects , Mitochondria/metabolism , Nuclear Proteins/metabolism , Patient Selection , Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha/metabolism , Protein Binding/genetics , SOXE Transcription Factors/genetics , SOXE Transcription Factors/metabolism , Skin Neoplasms/drug therapy , Skin Neoplasms/genetics , Skin Neoplasms/pathology , Transcription Factors/metabolism , Treatment Outcome , Triazoles/pharmacology , Triazoles/therapeutic use , Xenograft Model Antitumor Assays
4.
Mar Pollut Bull ; 120(1-2): 364-369, 2017 Jul 15.
Article in English | MEDLINE | ID: mdl-28521936

ABSTRACT

Swordfish (Xiphias gladius L., 1758) is an apex predator, highly migratory meso-pelagic fish widely distributed in the Atlantic Ocean and Mediterranean. As top predators, this fish may be the end reservoir of the bioaccumulation of trace elements in a food chain because they occupy higher trophic levels and are an important food source, causing them to be potentially hazardous to consume. This study aims to investigate the concentration of 18 trace elements of Swordfish, caught in the Mediterranean Sea and to discuss human exposure risks. The mean element levels in the fish muscles were clearly below the maximum allowable concentrations established by International food safety regulations. The data suggested that the risk is minor and acceptable for human health. The findings of this study amplify the scarce database on contaminants available, especially new data on "emerging elements", for this species from the Mediterranean Sea.


Subject(s)
Fishes , Risk Assessment , Trace Elements/analysis , Animals , Atlantic Ocean , Fisheries , Humans , Mediterranean Sea , Water Pollutants, Chemical
5.
Food Res Int ; 92: 119-127, 2017 02.
Article in English | MEDLINE | ID: mdl-28290289

ABSTRACT

The objective of this study was to investigate for the first time the influence of bread structure, volatile compounds, and oral processing on aroma perception. 3 types of French baguette were created using the same raw ingredients but different bread-making processes; they consequently varied in their crumb and crust structures. We characterized the initial volatile profiles of two bread structural subtypes-namely bread crumb and bread crumb with crust-using proton transfer reaction-mass spectrometry (PTR-MS) headspace analysis. Three types of bread were characterized by thirty-nine ion fragments from m/z 45 to 139. We then conducted a study in which 8 participants scored aroma attribute intensities for the different bread types and subtypes at 3 key stages of oral processing (10, 40, and 100% of individual swallowing time). At these 3 time points, we collected boli from the participants and characterized their volatile profiles using PTR-MS headspace analysis. The results suggest saliva addition dilutes volatile compounds, reducing volatile release during oral processing. Thus, a bread with high porosity and high hydration capacity was characterized by a low volatile release above boli. We examined the relationships between 4 aroma attributes of bread crumb with crust and 24 discriminatory fragment ions found in boli headspace. This study demonstrated for the first time that the perceived aroma of crumb with crust was influenced more by volatile profiles than by crumb texture. It thus contributes to our understanding of aroma perception dynamics and the mechanisms driving volatile release during oral processing in bread.


Subject(s)
Bread/analysis , Olfactory Perception , Adult , Female , Flour/analysis , Gas Chromatography-Mass Spectrometry , Humans , Male , Odorants/analysis , Taste , Triticum , Volatile Organic Compounds/analysis , Young Adult
6.
Food Funct ; 7(3): 1446-57, 2016 Mar.
Article in English | MEDLINE | ID: mdl-26857555

ABSTRACT

Oral processing during bread consumption is a key process related to the dynamics of texture perceptions, sensory stimuli release and starch digestion. The aim of this study was to determine the respective contribution of bread properties (composition and structure of crumb and crust) and of the oral physiology of subjects to the breakdown pathways in the mouth. The properties of the in vivo bread bolus obtained from eight healthy subjects were studied at three key points in time during their oral processing. The progressive lubrication and breakdown of bread were observed, as well as the beginning of the enzymatic degradation of starch. The study showed that "time" was the factor responsible for the greatest variability in bolus properties. Breakdown pathways were established for crumbs with and without crust. The presence of crust modified the oral processing, increasing, for instance, the heterogeneity of particle size at the middle of the oral processing sequence. Moreover, the hydration capacity of crust contributed to high starch degradation at swallowing time, in comparison with crumb alone. The main subject characteristics impacting bolus properties were the in-mouth duration, the individual masticatory index and the mouth volume, while the main bread properties explaining the bolus properties were the initial composition and the water-absorbing capacity. We concluded that both crumb and crust structures had an impact on the oral processing, affecting the capacity of hydration, the rheology and the breakdown degree of the bolus.


Subject(s)
Bread/analysis , Digestion , Mouth/metabolism , Triticum/chemistry , Adult , Female , Humans , Male , Particle Size , Rheology , Starch/analysis , Starch/metabolism , Taste , Triticum/metabolism , Water/analysis , Water/metabolism , Young Adult
7.
Food Res Int ; 87: 142-151, 2016 Sep.
Article in English | MEDLINE | ID: mdl-29606235

ABSTRACT

Texture perception is a multidimensional and dynamic phenomenon resulting from both the initial structure of food and its breakdown during oral processing. The aim of this study is to identify the respective contribution of food and bolus properties to temporal changes in texture perceptions during bread consumption. For this purpose, the perception dynamics of three French baguettes with dif\ferent structures were assessed through Temporal Dominance of Sensations and Progressive Profiling. Samples of crumb with and without crust were tasted by trained panelists. The intensities of nine texture attributes were evaluated at three key stages of oral processing (10%, 40% and 100% of individual swallowing time) using the Progressive Profiling method. Six of them were related with a Multiblock Partial Least Squares (MB-PLS) regression to the initial bread properties and to some bolus properties measured at these three stages. The evolution during oral processing of some attributes such as "soft", "dry", "doughy" and "sticky" was more influenced by modifications of bolus properties than by the initial characteristics of the breads. Among bolus properties, the MB-PLS highlighted that the hydration and texture properties of the bolus had a greater impact on texture perceptions than bolus structure. The "aerated" perception was more affected by the crumb structure, while the "heterogeneousness" and the "crispiness" were more affected by the presence of crust. This study thus contributes to improving our understanding of dynamic texture perceptions through a statistical model that takes the physical properties of bread and bolus during oral processing into account.

8.
J Fish Biol ; 87(2): 400-21, 2015 Aug.
Article in English | MEDLINE | ID: mdl-26177857

ABSTRACT

Sound production by the dusky grouper Epinephelus marginatus was monitored both in captivity and at two Mediterranean spawning sites during the summers of 2012 and 2013. The results of long-term passive acoustic recordings provide for the first time a description of the sounds produced by E. marginatus. Two types of sounds were mainly recorded and consisted of low-frequency booms that can be produced singly or in series with dominant frequencies below 100 Hz. Recordings in captivity validated these sounds as belonging to E. marginatus and suggested that they may be associated with reproductive displays usually performed during early stages of courtship behaviour. This study also allowed the identification of a third, low-frequency growl-like type of sound typically found in other grouper species. These growls were, however, not recorded in tanks and it is cautiously proposed that they are produced by E. marginatus. Acoustic signals attributed to E. marginatus were produced throughout the spawning season, with a diel pattern showing an increase before dusk, i.e., from 1900 to 2200 hours, before decreasing until the morning. The occurrence of sounds during the spawning season of this species suggests that they are probably involved in social activity occurring close to aggregation sites. Passive acoustics offer a helpful tool to monitor aggregation sites of this emblematic species in order to improve conservation efforts.


Subject(s)
Perciformes/physiology , Sexual Behavior, Animal , Vocalization, Animal , Acoustics , Animals , Female , Male , Mediterranean Sea , Sound
9.
Heredity (Edinb) ; 113(1): 74-85, 2014 Jul.
Article in English | MEDLINE | ID: mdl-24549110

ABSTRACT

The long generation time and large effective size of widespread forest tree species can result in slow evolutionary rate and incomplete lineage sorting, complicating species delimitation. We addressed this issue with the African timber tree genus Milicia that comprises two morphologically similar and often confounded species: M. excelsa, widespread from West to East Africa, and M. regia, endemic to West Africa. We combined information from nuclear microsatellites (nSSRs), nuclear and plastid DNA sequences, and morphological systematics to identify significant evolutionary units and infer their evolutionary and biogeographical history. We detected five geographically coherent genetic clusters using nSSRs and three levels of genetic differentiation. First, one West African cluster matched perfectly with the morphospecies M. regia that formed a monophyletic clade at both DNA sequences. Second, a West African M. excelsa cluster formed a monophyletic group at plastid DNA and was more related to M. regia than to Central African M. excelsa, but shared many haplotypes with the latter at nuclear DNA. Third, three Central African clusters appeared little differentiated and shared most of their haplotypes. Although gene tree paraphyly could suggest a single species in Milicia following the phylogenetic species concept, the existence of mutual haplotypic exclusivity and nonadmixed genetic clusters in the contact area of the two taxa indicate strong reproductive isolation and, thus, two species following the biological species concept. Molecular dating of the first divergence events showed that speciation in Milicia is ancient (Tertiary), indicating that long-living tree taxa exhibiting genetic speciation may remain similar morphologically.


Subject(s)
Biological Evolution , Genetic Speciation , Moraceae/anatomy & histology , Moraceae/genetics , Phylogeny , Africa , Base Sequence , Bayes Theorem , DNA Primers/genetics , Evolution, Molecular , Haplotypes/genetics , Microsatellite Repeats/genetics , Models, Genetic , Molecular Sequence Data , Multigene Family/genetics , Phylogeography , Sequence Analysis, DNA
10.
Mol Syndromol ; 4(4): 165-72, 2013 Apr.
Article in English | MEDLINE | ID: mdl-23801932

ABSTRACT

Mutations of CCM3/PDCD10 cause 10-15% of hereditary cerebral cavernous malformations. The phenotypic characterization of CCM3-mutated patients has been hampered by the limited number of patients harboring a mutation in this gene. This is the first report on molecular and clinical features of a large cohort of CCM3 patients. Molecular screening for point mutations and deletions was used to identify 54 CCM3-mutated index patients. Age at referral and clinical onset, type of inaugural events and presence of extra-axial lesions were investigated in these 54 index patients and 22 of their mutated relatives. Mean age at clinical onset was 23.0 ± 16 years. Clinical onset occurred before 10 years in 26% of the patients, and cerebral hemorrhage was the initial presentation in 72% of these patients. Multiple extra-axial, dural-based lesions were detected in 7 unrelated patients. These lesions proved to be meningiomas in 3 patients who underwent neurosurgery and pathological examination. This 'multiple meningiomas' phenotype is not associated with a specific CCM3 mutation. Hence, CCM3 mutations are associated with a high risk of early-onset cerebral hemorrhage and with the presence of multiple meningiomas.

11.
Front Plant Sci ; 4: 38, 2013.
Article in English | MEDLINE | ID: mdl-23515425

ABSTRACT

A complete understanding of the mechanistic basis of marine ecosystem functioning is only possible through integrative and interdisciplinary research. This enables the prediction of change and possibly the mitigation of the consequences of anthropogenic impacts. One major aim of the European Cooperation in Science and Technology (COST) Action ES0609 "Seagrasses productivity. From genes to ecosystem management," is the calibration and synthesis of various methods and the development of innovative techniques and protocols for studying seagrass ecosystems. During 10 days, 20 researchers representing a range of disciplines (molecular biology, physiology, botany, ecology, oceanography, and underwater acoustics) gathered at The Station de Recherches Sous-marines et Océanographiques (STARESO, Corsica) to study together the nearby Posidonia oceanica meadow. STARESO is located in an oligotrophic area classified as "pristine site" where environmental disturbances caused by anthropogenic pressure are exceptionally low. The healthy P. oceanica meadow, which grows in front of the research station, colonizes the sea bottom from the surface to 37 m depth. During the study, genomic and proteomic approaches were integrated with ecophysiological and physical approaches with the aim of understanding changes in seagrass productivity and metabolism at different depths and along daily cycles. In this paper we report details on the approaches utilized and we forecast the potential of the data that will come from this synergistic approach not only for P. oceanica but for seagrasses in general.

12.
Ann Phys Rehabil Med ; 54(3): 156-71, 2011 May.
Article in English, French | MEDLINE | ID: mdl-21515103

ABSTRACT

OBJECTIVE: To check whether the use of an autoquestionnaire is adapted to obtain information about perceptions of multiple sclerosis (MS) patients concerning access to healthcare in the Pays de la Loire region of France. PATIENTS AND METHODS: Patients with MS were asked to complete a questionnaire concerning access to 31 healthcare professionals or social services. The questionnaires were anonymous and consisted of one page for the patient and one page for a member of his or her entourage. The questionnaires were returned in a prepaid stamped addressed envelope. The first 130 exploitable questionnaires were analysed. RESULTS: Over 50% of patients with MS found access to general practitioners, neurologists, nurses and pharmacists useful, as well as access to less MS-specific specialists, for example, dentists, ophthalmologists or gynaecologists. Physical medicine and rehabilitation practitioners were not required until later in the course of the disease. Patients and their entourage rated the importance of access to care differently for bladder and sexual problems, and for support for cognitive and psychological problems. CONCLUSION: This study validates the use of a questionnaire to obtain information about patient perceptions of access to healthcare. The study also suggests a hierarchy of care needs, insufficient patient information, and disparities in access to care related to where the patients live.


Subject(s)
Health Services Accessibility , Multiple Sclerosis , Adult , Aged , Caregivers/psychology , Female , France/epidemiology , Health Services Needs and Demand , Humans , Male , Medicine , Middle Aged , Multiple Sclerosis/epidemiology , Multiple Sclerosis/psychology , Multiple Sclerosis/therapy , Patients/psychology , Self Report , Social Work , Socioeconomic Factors , Surveys and Questionnaires , Young Adult
13.
J Biotechnol ; 151(1): 114-21, 2011 Jan 10.
Article in English | MEDLINE | ID: mdl-21112357

ABSTRACT

The electrochemical impedance spectroscopy (EIS) technique has been used as a sensitive method to explore the effect of antibacterial molecules on immobilized bacteria and biofilm formation. In this work, we describe the electrochemical spectroscopy as a powerful method to monitor the effect of chlorhexidine digluconate (CHX-Dg) on polyelectrolyte immobilized Escherichia coli K12 MG1655 and the kinetics of cell adhesion on gold electrodes. The experimental impedance data were modeled with a Zview program to find the best equivalent electrical circuit and analyse its parameter's properties. Polyelectrolyte multilayer formation on the electrode surface and bacteria immobilization greatly increased the electron-transfer resistance (R(et)) and reduced the constant phase element (CPE(dl)). The effect of CHX-Dg was studied in a 0.5 x 10⁻4 mmol l⁻¹ to 0.5 mmol l⁻¹ range. The relation between the evolution of R(et) and CHX-Dg concentration was found to be negatively correlated. When CHX-Dg was added, the electrochemical monitoring of the bacterial kinetic adhesion showed that the electrode's capacity (C(P)) variation remained stable, demonstrating that the addition of CHX-Dg in the broth inhibited bacterial adhesion.


Subject(s)
Cell Adhesion/drug effects , Cells, Immobilized/drug effects , Chlorhexidine/analogs & derivatives , Electrochemical Techniques/methods , Escherichia coli/drug effects , Chlorhexidine/pharmacology , Electric Impedance , Electrodes , Escherichia coli/chemistry , Escherichia coli/cytology , Gold/chemistry , Microscopy, Atomic Force , Microscopy, Fluorescence
14.
Equine Vet J Suppl ; (38): 475-81, 2010 Nov.
Article in English | MEDLINE | ID: mdl-21059048

ABSTRACT

REASONS FOR PERFORMING STUDY: Whereas the effect of heel configuration on the tension of the suspensory apparatus is well documented in the literature, there are few reports of joint contact force components in the equine distal forelimb. OBJECTIVES: To improve understanding of the effect of heel configuration on equine digit joint loading, a sensitivity analysis was performed to compare the effect of a raised heel on joint contact force components in the coffin and fetlock joints during the stance phase of the trot. MATERIALS AND METHODS: Four Warmblood horses were used. An inverse dynamic analysis was carried out using kinematic and kinetic data. Taking into account the tendon wrapping forces (WF) around the sesamoid bones in the calculations, the joint contact forces (CF) were estimated for the coffin and fetlock joints during the trot stance phase (4 m/s). To test the sensitivity of the results to heel configuration changes, calculations were performed repeatedly for different heel configurations (raised by 0, 6 and 12°). A one-way ANOVA with repeated measures was used to test the effect of heel configuration (at the 3 levels) (α = 0.05; P < 0.05; post hoc testing: Bonferroni). RESULTS: For heel configurations raised from 0-12°: whereas the tension of the deep digital flexor tendon decreased and the tension of the superficial digital flexor tendon increased, for the coffin joint the peak WF (1.4 ± 0.25 bwt; 1.2 ± 0.2 bwt; 0.95 ± 0.1 bwt) and the peak CF (2.45 ± 0.25 bwt; 2.2 ± 0.2 bwt; 2 ± 0.1 bwt) decreased significantly (P < 0.05). For the fetlock joint, the peak WF (3.8 ± 0.7 bwt; 4.1 ± 0.3 bwt; 4.4 ± 0.25 bwt) and the peak CF (4.35 ± 0.7 bwt; 4.7 ± 0.35 bwt; 5 ± 0.3 bwt) increased, but not significantly. CONCLUSION: This analysis suggests that the coffin joint loading and fetlock joint loading are strongly connected. The heel configuration may influence both coffin joint and fetlock joint contact force components.


Subject(s)
Foot/physiology , Forelimb/physiology , Horses/physiology , Joints/physiology , Animals , Biomechanical Phenomena , Female , Hoof and Claw/physiology , Male
15.
Environ Monit Assess ; 156(1-4): 435-50, 2009 Sep.
Article in English | MEDLINE | ID: mdl-18720018

ABSTRACT

Watercourses are complex ecosystems where numerous economic, ecological and heritage issues converge. To ensure their efficient management it is essential to have a full description of these multifunctional ecosystems and to know their evolution over time. This paper describes a method for monitoring watercourses and their riparian strips developed in Wallonia (southern Belgium). It is based on an inventory constructed by stratified random sampling comprising 1,071 sampling plots distributed over a total length of 24,600 km of watercourses covered from their source. Each sampling plot is surveyed and measurements and fine observations are made on watercourse segments 50 m long. The method developed, which was applied on a regional scale, could easily be transposed to other entities, from large river basins, to an entire country. Examples of results obtained from a first inventory phase demonstrate the utility of this tool designed to supply qualitative and quantitative information to assist watercourse management.


Subject(s)
Environmental Monitoring/methods , Rivers , Belgium , Geography
16.
J Mol Microbiol Biotechnol ; 17(1): 12-9, 2009.
Article in English | MEDLINE | ID: mdl-18818488

ABSTRACT

BACKGROUND: Quorum sensing (QS) is a process by which bacteria communicate with diffusible chemical signaling molecules called autoinducers (AIs). The autoinducer-2 signal (AI-2) produced by the LuxS protein mediates interspecies communication among Gram-positive and Gram-negative bacteria. In this study, we report that luxS-dependent QS is involved in the formation of Streptococcus mutans biofilms. METHODS: An S. mutans luxS mutant was constructed, and the differences in growth and biofilm formation were compared between the wild-type strain and the mutant strain. To quantificationally analyze the kinetic biofilm formation of the mutant strain, an assay of BioFilm Ring Test(R) was applied. RESULTS: There is a small increase in the growth of the luxS mutant strain after the stationary phase, compared with the parent strain. However during the exponential period, there were no significant differences. Using the BioFilm Ring Test(R), it was demonstrated that this luxS mutation was able to accelerate biofilm formation on a polystyrene surface during the mid-exponential growth phase. With 1% glucose treatment, even greater differences were observed between the mutant strain and its parental strain. CONCLUSION: These data suggest that a luxS-dependent signal may play an important role in the biofilm formation of S. mutans.


Subject(s)
Bacterial Proteins/physiology , Biofilms/growth & development , Carbon-Sulfur Lyases/physiology , Gene Expression Regulation, Bacterial , Quorum Sensing , Signal Transduction , Streptococcus mutans/physiology , Bacterial Proteins/genetics , Carbon-Sulfur Lyases/genetics , Gene Knockout Techniques , Glucose/metabolism
18.
Bioelectrochemistry ; 71(2): 118-25, 2007 Nov.
Article in English | MEDLINE | ID: mdl-17398167

ABSTRACT

In recent years, cell-based biosensors (CBBs) have been very useful in biomedicine, food industry, environmental monitoring and pharmaceutical screening. They constitute an economical substitute for enzymatic biosensors, but cell immobilization remains a limitation in this technology. To investigate into the potential applications of cell-based biosensors, we describe an electrochemical system based on a microbial biosensor using an Escherichia coli K-12 derivative as a primary transducer to detect biologically active agents. pH variations were recorded by an ion-sensitive field effect transistor (ISFET) sensor on bacteria immobilized in agarose gels. The ISFET device was directly introduced in 100 ml of this mixture or in a miniaturized system using a dialysis membrane that contains 1 ml of the same mixture. The bacterial activity could be detected for several days. The extracellular acidification rate (ECAR) was analyzed with or without the addition of a culture medium or an antibiotic solution. At first, the microorganisms acidified their micro-environment and then they alkalinized it. These two phases were attributed to an apparent substrate preference of bacteria. Cell treatment with an inhibitor or an activator of their metabolism was then monitored and streptomycin effect was tested.


Subject(s)
Biosensing Techniques/methods , Cells, Immobilized/metabolism , Escherichia coli K12/metabolism , Anti-Bacterial Agents/pharmacology , Biosensing Techniques/instrumentation , Calibration , Dialysis , Electrochemistry , Hydrogen-Ion Concentration , Miniaturization , Reproducibility of Results , Sepharose/metabolism , Streptomycin
19.
Diabetes Metab ; 32(5 Pt 1): 427-32, 2006 Nov.
Article in English | MEDLINE | ID: mdl-17110897

ABSTRACT

AIM: The purpose of this national multicenter prospective study by the French EVADIAC group was to investigate the possibility that continuous intraperitoneal insulin infusion using an implanted pump (CIpii) increases the risk of autoimmune disease in type 1 diabetic patients as it increased anti-insulin immunogenicity. METHODS: Prevalence of clinical (Hashimoto's disease, hyperthyroidism, gastric atrophic disease and vitiligo) and subclinical (presence of anti-thyroperoxidase antibodies, anti-intrinsic factor antibodies, abnormal TSH levels) autoimmune diseases was estimated by comparing two groups of patients already treated by either CIpii (n=154) or external pump (CSII) (n=121) for an average of 6 years. Incidence of autoimmune disease was determined by comparing the same measurements one year after inclusion. RESULTS: No significant difference was observed for the total prevalence of clinical and subclinical auto-immune thyroid and gastric di-seases (35.6% and 3.2% respectively in the CIpii group versus 40.4% and 2.6% in the CSII group). No significant difference for the incidence of clinical and subclinical auto-immune diseases was observed: 7.2% and 0% in CIpii and 7.3% and 1.7% in CSII. CONCLUSION: As previously shown AIA (anti-insulin antibodies) levels were higher in CIpii than in CSII (32.9% vs 20.2%, P<0.0001) but no correlation was observed with either clinical or subclinical autoimmune disease. This large-scale study eliminates the possibility that CIpii increases the risk of autoimmune disease.


Subject(s)
Autoimmune Diseases/epidemiology , Diabetes Mellitus, Type 1/drug therapy , Diabetes Mellitus, Type 1/immunology , Insulin Infusion Systems/adverse effects , Adult , Autoantibodies/blood , Female , Hashimoto Disease/epidemiology , Humans , Incidence , Male , Prevalence , Vitiligo/epidemiology
20.
Thyroid ; 15(9): 1067-72, 2005 Sep.
Article in English | MEDLINE | ID: mdl-16187916

ABSTRACT

INTRODUCTION: We previously reported a high thyroglobulin autoantibodies (TgAb) prevalence in healthy Sri Lankans after iodine supplementation. In the present study 58 TgAb-positive schoolgirls were followed up after 5 years of continued iodination. The objectives were: (1) to observe the longitudinal profile of TgAb epitope specificities and (2) to examine the relationship between these specificities and the course of thyroid autoimmunity in this population. METHODS: Paired subjects' sera (at onset and at 5-year follow-up) were tested for TgAb, thyroid peroxidase antibody (TPOAb), and TgAb epitope-specificity. Epitope reactivity was determined by employing a panel of 10 murine monoclonal antibodies (Tg-mAbs) directed against 6 Tg antigenic clusters (I-VI) in competitive enzyme-linked immunosorbent assay (ELISA) reactions with test sera. RESULTS: The overall pattern of epitope recognition in individual subject's sera remained preserved over the time period. Nine subjects showed restricted specificities while majority of the subjects were broadly heterogeneous. At follow-up, median TgAb concentration in the restricted group was higher than in the unrestricted (1650 versus 110 kIU/L; p < 0.005). Epitope specificity was a stronger determinant of TgAb persistence than the height of the initial TgAb response or the TPOAb status of subjects. CONCLUSION: Tg epitope reactivity pattern in iodised populations may identify subjects at greater risk of developing autoimmune thyroid disease (AITD).


Subject(s)
Autoantibodies/analysis , Epitopes/immunology , Thyroglobulin/immunology , Alkaline Phosphatase/analysis , Alkaline Phosphatase/metabolism , Antibodies, Monoclonal/analysis , Antibody Specificity , Binding, Competitive , Child , Enzyme-Linked Immunosorbent Assay , Female , Humans , Longitudinal Studies , Sri Lanka , Thyroid Function Tests
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