To distinguish species or populations using morphometric data is generally processed through multivariate analyses, in particular the discriminant analysis. We explored another approach based on the maximum likelihood...To distinguish species or populations using morphometric data is generally processed through multivariate analyses, in particular the discriminant analysis. We explored another approach based on the maximum likelihood method. Simple statistics based on the assumption of normal distribution at a single variable allows to compute the chance of observing a particular data （or sample） in a given reference group. When data are described by more than one variable, the maximum likelihood （MLi） approach allows to combine these chances to find the best fit for the data. Such approach assumes independence between variables. The assumptions of normal distribution of variables and independence between them are frequently not met in morphometrics, but improvements may be obtained after some mathematical transformations. Provided there is strict anatomical correspondence of variables between unknown and reference data, the MLi classification produces consistent classification. We explored this approach using various input data, and compared validated classification scores with the ones obtained after the Mahalanobis distance-based classification. The simplicity of the method, its fast computation, performance and versatility, make it an interesting complement to other classification techniques.展开更多
Various studies on the difference of distal femoral condyles between genders have been reported recently in order to provide anatomic information for knee prosthesis design and surgical planning in total knee arthropl...Various studies on the difference of distal femoral condyles between genders have been reported recently in order to provide anatomic information for knee prosthesis design and surgical planning in total knee arthroplasty. They also had the objective to be used as a sex recognition character, as may be needed in forensic medicine. Except for a recent 3D approach on the distal femur, most of the studies used dimensional information or aspect ratio but not shape. Our 2D study aimed to determine the size and shape variation of femoral condyles in Thais, considering age, sex and sides. One hundred and twenty-four cadaveric femurs （male 84 legs and female 40 legs） were dissected. The specimens were photographed by digital camera and images were analyzed using three geometric techniques： （i） the landmark-based method （5 landmarks）, （ii） with or without addition of 23 sliding semilandmark and （iii） the outline-based methods. From the resulting geometric coordinates, size and shape were extracted for comparisons between genders and sides. Between sides, directional asymmetry could be detected only for shape variation, and only when introducing curves in the analyses （either through the semilandmarks technique or through the outline-based one）. Non-directional asymmetry, probably fluctuating asymmetry, was detected for size, as well as for shape, in both genders. Sex discrimination was performed for each geometric technique using two classification methods： the Mahalanobis distance classification and the Maximum likelihood classification. The latter provided much more satisfactory gender validated reclassification （87%） than shape （72%）.展开更多
Agroecosystems in the Senegalese groundnut basin experience long periods of high temperatures and drought, which disrupt the stability of soil microbial communities. This study evaluated how that stability is affected...Agroecosystems in the Senegalese groundnut basin experience long periods of high temperatures and drought, which disrupt the stability of soil microbial communities. This study evaluated how that stability is affected by homefields and outfields’ agricultural practices and the duration of heat stress. Specifically, we collected soils from organically farmed fields that receive continual high inputs of manure (homefields), and from fields that are rarely manured (outfields). Soil samples were submitted to artificial heat stress at 60°C for 3, 14, and 28 days, followed by 28 days of recovery at 28°C. We examined the functional stability of microbial communities by quantifying C mineralization, and characterized the stability of the communities’ taxonomic compositions via high-throughput DNA sequencing. We found that the microbial communities have a low resistance to heat stress in soils from both types of fields. However, the manuring practice does affect how the functional stability of microbial communities responds to different durations of heat stress. Although functional stability was not recovered fully in either soil, microbial community resilience seemed to be greater in homefield soils. Differences in manuring practices also affected the structural taxonomic stability of microbial communities: relative abundances of Bacilli, Chloroflexia, Actinobacteria and Sordariomycetes increased in the homefield stressed-soils, but decreased significantly in outfield soils. In contrast, relative abundances of α-Proteobacteria, γ-Proteobacteria and Eurotiomycetes increased significantly in outfield stressed-soils, while decreasing significantly in the homefield soils. Relative abundances of Bacilli changed little in outfield soils, indicating that this taxon is resistant to heat stress. In summary, the microbial communities’ capacities to resist heat stress and recover from it depend upon the organic richness of the soil (i.e., manuring practice) and the adaptation of soil microbes to environmental conditions.展开更多
Human African trypanosomiasis (HAT), or sleeping sickness, caused by Trypanosoma brucei gambiense, is associated with diverse clinical outcomes. Host’s genetic factors involved in immunity are potential factors that ...Human African trypanosomiasis (HAT), or sleeping sickness, caused by Trypanosoma brucei gambiense, is associated with diverse clinical outcomes. Host’s genetic factors involved in immunity are potential factors that can regulate infection. Genetic polymorphisms within HLA-G could influence the level of HLA-G expression and therefore play a critical role in infection outcomes. The goal of our study was to investigate the association of 14 bp Indel HLA-G polymorphism with the susceptibility/resistance to HAT. DNA samples were collected from 119 cases, 221 controls and 43 seropositive individuals living in Ivorian HAT foci. The 14 bp Indel polymorphism was determined by PCR. Homozygous individuals for 14 bp insertion had a lower risk of progressing to active HAT (p = 0.012, OR = 0.27, 95% CI: 0.09 - 0.8). Moreover, the frequency of 14 bp insertion homozygous genotype was higher in the seropositive group (11%) than in the HAT cases group (3%) (p = 0.043, OR = 0.27, 95% CI: 0.07 - 0.99), which suggested a protective effect of 14 bp insertion homozygous genotype. Genetic polymorphisms in HLA-G may be associated with a variable risk to develop HAT. The 14 bp insertion appears to favour the occurrence of long-lasting T. b. gambiense latent infections.展开更多
Trypanosomiasis,transmitted by tsetse flies(Glossina spp.),poses a significant health threat in 36 sub-Saharan African countries.Current control methods targeting tsetse flies,while effective,allow reinfestation.This ...Trypanosomiasis,transmitted by tsetse flies(Glossina spp.),poses a significant health threat in 36 sub-Saharan African countries.Current control methods targeting tsetse flies,while effective,allow reinfestation.This study investigates paratransgenesis,a novel strategy to engineer symbiotic bacteria in tsetse flies,Sodalis glossinidius,to deliver anti-trypanosome compounds.Disrupting the trypanosome life cycle within the fly and reducing parasite transmission could offer a sustainable solution for trypanosomiasis control.In this context,we tested the effect of cecropin,reported to be lethal for Trypanosoma cruzi(Chagas disease)and TbgTCTP(Translationally Controlled Tumor Protein from Trypanosoma brucei gambiense),previously reported to modulate the growth of bacteria isolated from the fly microbiome,to delay the first peak of parasitemia and the death of trypanosome-infected mice.We have successfully cloned and transfected the genes encoding the two proteins into Sodalis strains.These Sodalis recombinant strains(recSodalisTbgTCTP and recSodaliscecropin)have been then microinjected into the L3 larval stage of Glossina palpalis gambiensis flies.The stability of the cloned genes was checked up to the 20th day after microinjection of recSodalis.The rate of fly emergence from untreated pupae was 95%;it was reduced by nearly 50%due to the mechanical injury caused by microinjection.It decreased to nearly 7%when larvae were injected with recSodalisTbgTCTP,which suggests TCTP could have a lethal impact to larvae development.When challenged with T.brucei gambiense,a slightly lower,but statistically non-significant,infection rate was recorded in flies harboring recSodaliscecropin compared to control flies.The effect of recSodalisTbgTCTP could not be measured due to the very low rate of fly emergence after corresponding treatment of the larvae.The results do not allow to conclude on the effect of cecropin or TCTP,delivered by para-transgenesis into the fly's gut,on the fly infection by the trypanosome.Nevertheless,the results are encouraging insofar as the technical approach works on the couple G.p.gambiensis/T.brucei gambiense.The next step will be to optimize the system and test other targets chosen among the ESPs(Excreted-Secreted Proteins)of the trypanosome secretum,or the differentially expressed genes associated with the sensitivity/resistance of the fly to trypanosome infection.展开更多
Background:In recent years,a programme of vector control,screening and treatment of gambiense human African trypanosomiasis(gHAT)infections led to a rapid decline in cases in the Mandoul focus of Chad.To represent the...Background:In recent years,a programme of vector control,screening and treatment of gambiense human African trypanosomiasis(gHAT)infections led to a rapid decline in cases in the Mandoul focus of Chad.To represent the biology of transmission between humans and tsetse,we previously developed a mechanistic transmission model,fitted to data between 2000 and 2013 which suggested that transmission was interrupted by 2015.The present study outlines refinements to the model to:(1)Assess whether elimination of transmission has already been achieved despite low-level case reporting;(2)quantify the role of intensified interventions in transmission reduction;and(3)predict the trajectory of gHAT in Mandoul for the next decade under different strategies.Method:Our previous gHAT transmission model for Mandoul was updated using human case data(2000-2019)and a series of model refinements.These include how diagnostic specificity is incorporated into the model and improvements to the fitting method(increased variance in observed case reporting and how underreporting and improvements to passive screening are captured).A side-by-side comparison of fitting to case data was performed between the models.Results:We estimated that passive detection rates have increased due to improvements in diagnostic availability in fixed health facilities since 2015,by 2.1-fold for stage 1 detection,and 1.5-fold for stage 2.We find that whilst the diagnostic algorithm for active screening is estimated to be highly specific(95%credible interval(CI):99.9-100%,Specificity=99.9%),the high screening and low infection levels mean that some recently reported cases with no parasitological confirmation might be false positives.We also find that the focus-wide tsetse reduction estimated through model fitting(95%CI:96.1-99.6%,Reduction=99.1%)is comparable to the reduction previously measured by the decline in tsetse catches from monitoring traps.In line with previous results,the model suggests that transmission was interrupted in 2015 due to intensified interventions.Conclusions:We recommend that additional confirmatory testing is performed in Mandoul to ensure the endgame can be carefully monitored.More specific measurement of cases,would better inform when it is safe to stop active screening and vector control,provided there is a strong passive surveillance system in place.展开更多
基金financed by the Chaires Merieux foundation(Paris,France)Pontifical Catholic University of Ecuador(M 13480)
文摘To distinguish species or populations using morphometric data is generally processed through multivariate analyses, in particular the discriminant analysis. We explored another approach based on the maximum likelihood method. Simple statistics based on the assumption of normal distribution at a single variable allows to compute the chance of observing a particular data （or sample） in a given reference group. When data are described by more than one variable, the maximum likelihood （MLi） approach allows to combine these chances to find the best fit for the data. Such approach assumes independence between variables. The assumptions of normal distribution of variables and independence between them are frequently not met in morphometrics, but improvements may be obtained after some mathematical transformations. Provided there is strict anatomical correspondence of variables between unknown and reference data, the MLi classification produces consistent classification. We explored this approach using various input data, and compared validated classification scores with the ones obtained after the Mahalanobis distance-based classification. The simplicity of the method, its fast computation, performance and versatility, make it an interesting complement to other classification techniques.
文摘Various studies on the difference of distal femoral condyles between genders have been reported recently in order to provide anatomic information for knee prosthesis design and surgical planning in total knee arthroplasty. They also had the objective to be used as a sex recognition character, as may be needed in forensic medicine. Except for a recent 3D approach on the distal femur, most of the studies used dimensional information or aspect ratio but not shape. Our 2D study aimed to determine the size and shape variation of femoral condyles in Thais, considering age, sex and sides. One hundred and twenty-four cadaveric femurs （male 84 legs and female 40 legs） were dissected. The specimens were photographed by digital camera and images were analyzed using three geometric techniques： （i） the landmark-based method （5 landmarks）, （ii） with or without addition of 23 sliding semilandmark and （iii） the outline-based methods. From the resulting geometric coordinates, size and shape were extracted for comparisons between genders and sides. Between sides, directional asymmetry could be detected only for shape variation, and only when introducing curves in the analyses （either through the semilandmarks technique or through the outline-based one）. Non-directional asymmetry, probably fluctuating asymmetry, was detected for size, as well as for shape, in both genders. Sex discrimination was performed for each geometric technique using two classification methods： the Mahalanobis distance classification and the Maximum likelihood classification. The latter provided much more satisfactory gender validated reclassification （87%） than shape （72%）.
文摘Agroecosystems in the Senegalese groundnut basin experience long periods of high temperatures and drought, which disrupt the stability of soil microbial communities. This study evaluated how that stability is affected by homefields and outfields’ agricultural practices and the duration of heat stress. Specifically, we collected soils from organically farmed fields that receive continual high inputs of manure (homefields), and from fields that are rarely manured (outfields). Soil samples were submitted to artificial heat stress at 60°C for 3, 14, and 28 days, followed by 28 days of recovery at 28°C. We examined the functional stability of microbial communities by quantifying C mineralization, and characterized the stability of the communities’ taxonomic compositions via high-throughput DNA sequencing. We found that the microbial communities have a low resistance to heat stress in soils from both types of fields. However, the manuring practice does affect how the functional stability of microbial communities responds to different durations of heat stress. Although functional stability was not recovered fully in either soil, microbial community resilience seemed to be greater in homefield soils. Differences in manuring practices also affected the structural taxonomic stability of microbial communities: relative abundances of Bacilli, Chloroflexia, Actinobacteria and Sordariomycetes increased in the homefield stressed-soils, but decreased significantly in outfield soils. In contrast, relative abundances of α-Proteobacteria, γ-Proteobacteria and Eurotiomycetes increased significantly in outfield stressed-soils, while decreasing significantly in the homefield soils. Relative abundances of Bacilli changed little in outfield soils, indicating that this taxon is resistant to heat stress. In summary, the microbial communities’ capacities to resist heat stress and recover from it depend upon the organic richness of the soil (i.e., manuring practice) and the adaptation of soil microbes to environmental conditions.
文摘Human African trypanosomiasis (HAT), or sleeping sickness, caused by Trypanosoma brucei gambiense, is associated with diverse clinical outcomes. Host’s genetic factors involved in immunity are potential factors that can regulate infection. Genetic polymorphisms within HLA-G could influence the level of HLA-G expression and therefore play a critical role in infection outcomes. The goal of our study was to investigate the association of 14 bp Indel HLA-G polymorphism with the susceptibility/resistance to HAT. DNA samples were collected from 119 cases, 221 controls and 43 seropositive individuals living in Ivorian HAT foci. The 14 bp Indel polymorphism was determined by PCR. Homozygous individuals for 14 bp insertion had a lower risk of progressing to active HAT (p = 0.012, OR = 0.27, 95% CI: 0.09 - 0.8). Moreover, the frequency of 14 bp insertion homozygous genotype was higher in the seropositive group (11%) than in the HAT cases group (3%) (p = 0.043, OR = 0.27, 95% CI: 0.07 - 0.99), which suggested a protective effect of 14 bp insertion homozygous genotype. Genetic polymorphisms in HLA-G may be associated with a variable risk to develop HAT. The 14 bp insertion appears to favour the occurrence of long-lasting T. b. gambiense latent infections.
文摘Trypanosomiasis,transmitted by tsetse flies(Glossina spp.),poses a significant health threat in 36 sub-Saharan African countries.Current control methods targeting tsetse flies,while effective,allow reinfestation.This study investigates paratransgenesis,a novel strategy to engineer symbiotic bacteria in tsetse flies,Sodalis glossinidius,to deliver anti-trypanosome compounds.Disrupting the trypanosome life cycle within the fly and reducing parasite transmission could offer a sustainable solution for trypanosomiasis control.In this context,we tested the effect of cecropin,reported to be lethal for Trypanosoma cruzi(Chagas disease)and TbgTCTP(Translationally Controlled Tumor Protein from Trypanosoma brucei gambiense),previously reported to modulate the growth of bacteria isolated from the fly microbiome,to delay the first peak of parasitemia and the death of trypanosome-infected mice.We have successfully cloned and transfected the genes encoding the two proteins into Sodalis strains.These Sodalis recombinant strains(recSodalisTbgTCTP and recSodaliscecropin)have been then microinjected into the L3 larval stage of Glossina palpalis gambiensis flies.The stability of the cloned genes was checked up to the 20th day after microinjection of recSodalis.The rate of fly emergence from untreated pupae was 95%;it was reduced by nearly 50%due to the mechanical injury caused by microinjection.It decreased to nearly 7%when larvae were injected with recSodalisTbgTCTP,which suggests TCTP could have a lethal impact to larvae development.When challenged with T.brucei gambiense,a slightly lower,but statistically non-significant,infection rate was recorded in flies harboring recSodaliscecropin compared to control flies.The effect of recSodalisTbgTCTP could not be measured due to the very low rate of fly emergence after corresponding treatment of the larvae.The results do not allow to conclude on the effect of cecropin or TCTP,delivered by para-transgenesis into the fly's gut,on the fly infection by the trypanosome.Nevertheless,the results are encouraging insofar as the technical approach works on the couple G.p.gambiensis/T.brucei gambiense.The next step will be to optimize the system and test other targets chosen among the ESPs(Excreted-Secreted Proteins)of the trypanosome secretum,or the differentially expressed genes associated with the sensitivity/resistance of the fly to trypanosome infection.
基金This work was supported by the Bill and Melinda Gates Foundation(www.gatesfoundation.org)through the Human African Trypanosomiasis Modelling and Economic Predictions for Policy(HAT MEPP)project[OPP1177824 and INV-005121](CH,REC,PEB,MA,EHC,KSR)through the NTD Modelling Consortium[OPP1184344](KSR),and the Trypa-NO!project[INV-008412 and INV-001785](PRB,AP,SJT,PS and IT)+1 种基金SJT received funding from the Biotechnology and Biological Sciences Research Council(www.bbsrc.ukri.orgGrants BB/S01375X/1,BB/S00243X/1,BB/P005888/1).The funders had no role in study design,data collection and analysis,decision to publish,or preparation of the manuscript.
文摘Background:In recent years,a programme of vector control,screening and treatment of gambiense human African trypanosomiasis(gHAT)infections led to a rapid decline in cases in the Mandoul focus of Chad.To represent the biology of transmission between humans and tsetse,we previously developed a mechanistic transmission model,fitted to data between 2000 and 2013 which suggested that transmission was interrupted by 2015.The present study outlines refinements to the model to:(1)Assess whether elimination of transmission has already been achieved despite low-level case reporting;(2)quantify the role of intensified interventions in transmission reduction;and(3)predict the trajectory of gHAT in Mandoul for the next decade under different strategies.Method:Our previous gHAT transmission model for Mandoul was updated using human case data(2000-2019)and a series of model refinements.These include how diagnostic specificity is incorporated into the model and improvements to the fitting method(increased variance in observed case reporting and how underreporting and improvements to passive screening are captured).A side-by-side comparison of fitting to case data was performed between the models.Results:We estimated that passive detection rates have increased due to improvements in diagnostic availability in fixed health facilities since 2015,by 2.1-fold for stage 1 detection,and 1.5-fold for stage 2.We find that whilst the diagnostic algorithm for active screening is estimated to be highly specific(95%credible interval(CI):99.9-100%,Specificity=99.9%),the high screening and low infection levels mean that some recently reported cases with no parasitological confirmation might be false positives.We also find that the focus-wide tsetse reduction estimated through model fitting(95%CI:96.1-99.6%,Reduction=99.1%)is comparable to the reduction previously measured by the decline in tsetse catches from monitoring traps.In line with previous results,the model suggests that transmission was interrupted in 2015 due to intensified interventions.Conclusions:We recommend that additional confirmatory testing is performed in Mandoul to ensure the endgame can be carefully monitored.More specific measurement of cases,would better inform when it is safe to stop active screening and vector control,provided there is a strong passive surveillance system in place.
