Detection of tick-borne pathogens in the pangolin tick, Amblyomma javanense, from Vietnam and Laos, including a novel species of Trypanosoma.

Two species of Southeast Asian pangolins (the Chinese pangolin, Manis pentadactyla and the Malayan or Sunda pangolin, Manis javanica) are critically endangered species. Therefore, knowledge on their parasitic infections is very important, especially considering ticks that can transmit which pathogens. In this study, 32 pangolin ticks (Amblyomma javanense), that were collected in Vietnam and Laos, were analyzed with molecular methods for the presence of tick-borne pathogens. Two members of the family Anaplasmataceae were shown to be present in 14 pangolin ticks, i.e., Candidatus Anaplasma pangolinii and an Ehrlichia sp. In three ticks, a single Rickettsia genotype was also detected, and in seven ticks four 18S rRNA sequence variants of a Babesia sp. Most importantly, a novel protozoan agent, tentatively called here Trypanosoma sp. "PAT14" was detected in one A. javanense nymph. These results imply the first molecular finding of any species of Anaplasma, Ehrlichia and Babesia in pangolin ticks from Vietnam and Laos. On the other hand, detection of a new tick-associated Trypanosoma sp. in A. javanense from Southeast Asia is not only important from a taxonomic point of view, but it is also the first finding of any trypanosomes in the genus Amblyomma in Eurasia and adds pangolins to the potential placental mammalian hosts of any trypanosomes.

A morpho-phylogenetic update on ixodid ticks infesting cattle and buffalos in Vietnam, with three new species to the fauna and a checklist of all species indigenous to the country.

BACKGROUND: Southeast Asia is regarded as a hotspot for the diversity of ixodid ticks. In this geographical region, Vietnam extends through both temperate and tropical climate zones and therefore has a broad range of tick habitats. However, molecular-phylogenetic studies on ixodid tick species have not been reported from this country. METHODS: In this study, 1788 ixodid ticks were collected from cattle, buffalos and a dog at 10 locations in three provinces of northern Vietnam. Tick species were identified morphologically, and representative specimens were molecularly analyzed based on the cytochrome c oxidase subunit I (cox1) and 16S rRNA genes. Fifty-nine tick species that are indigenous in Vietnam were also reviewed in the context of their typical hosts in the region. RESULTS: Most ticks removed from cattle and buffalos were identified as Rhipicephalus microplus, including all developmental stages. Larvae and nymphs were found between January and July but adults until December. Further species identified from cattle were Rhipicephalus linnaei, Rhipicephalus haemaphysaloides, Amblyomma integrum and Haemaphysalis cornigera. Interestingly, the latter three species were represented only by adults, collected in one province: Son La. The dog was infested with nymphs and adults of R. linnaei in July. Phylogenetically, R. microplus from Vietnam belonged to clade A of this species, and R. haemaphysaloides clustered separately from ticks identified under this name in China, Taiwan and Pakistan. Amblyomma integrum from Vietnam belonged to the phylogenetic group of haplotypes of an Amblyomma sp. reported from Myanmar. The separate clustering of H. cornigera from Haemaphysalis shimoga received moderate support. CONCLUSIONS: Three tick species (R. linnaei, A. integrum and H. cornigera) are reported here for the first time in Vietnam, thus increasing the number of indigenous tick species to 62. Clade A of R. microplus and at least R. linnaei from the group of Rhipicephalus sanguineus sensu lato occur in the country. There is multiple phylogenetic evidence that different species might exist among the ticks that are reported under the name R. haemaphysaloides in South and East Asia. This is the first report of A. integrum in Southeastern Asia.

Association between Bacteroides fragilis and Fusobacterium nucleatum infection and colorectal cancer in Vietnamese patients.

BACKGROUND: Colorectal cancer (CRC) is a significant global health concern, and understanding the role of specific bacterial infections in its development and progression is of increasing interest. This cross-sectional study investigated the associations between Bacteroides fragilis (B. fragilis) and Fusobacterium nucleatum (F. nucleatum) infections and Vietnamese CRC patients. METHODS: 192 patients with either polyps or CRC at varying stages were recruited from May 2017 to December 2020. Real-time PCR assessed infection rates and bacterial loads in CRC tissues. RESULTS: B. fragilis infection was notably higher in CRC tissues (51.6 %) than polyps (9.4 %), with a fivefold higher relative load. Positive associations were found in stages II and III, indicating a fivefold increase in CRC progression risk. F. nucleatum infection rates were significantly higher in CRC tissues (55.2 %) than in polyps (10.5 %). In stage II, the infection rate exceeded that in adjacent tissues. The relative load of F. nucleatum was higher in stage III than in stages I and II. Positive F. nucleatum patients had a 3.2 times higher risk of CRC progression. CONCLUSION: These findings suggest associations between loading of F. nucleatum or/and B. fragilis with the advanced stages of CRC.

An isothermal CRISPR- based lateral flow assay for detection of Neisseria meningitidis.

BACKGROUND: Neisseria meningitidis can cause life-threatening meningococcal meningitis and meningococcemia. Old standard microbiological results from CSF/blood cultures are time consuming. This study aimed to combine the sensitivity of loop-mediated isothermal nucleic acid amplification (LAMP) with the specificity of CRISPR/Cas12a cleavage to demonstrate a reliable diagnostic assay for rapid detection of N. meningitidis. METHODS: A total of n = 139 samples were collected from patients with suspected meningococcal disease and were used for evaluation. The extracted DNA was subjected to qualitative real-time PCR, targeting capsular transporter gene (ctrA) of N. meningitidis. LAMP-specific primer pairs, also targeting the ctrA, were designed and the LAMP products were subjected to CRISPR/Cas12 cleavage reaction. the readout was on a lateral flow strip. Sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of LAMP-CRISPR/Cas was compared with real-time PCR assays. The limit of detection (LOD) was established with serial dilutions of the target N. meningitidis DNA and calculated by Probit regression analysis. RESULTS: Six LAMP assay-specific primers were developed targeting the ctrA gene of N. meningitidis, which is conserved in all meningococcal serogroups. The LAMP primers did not amplify DNA from other bacterial DNA tested, showing 100% specificity. The use of 0.4 M betaine increased the sensitivity and stability of the reaction. LAMP-CRISPR/Cas detected meningococcal serogroups (B, C, W). The assay showed no cross-reactivity and was specific for N. meningitidis. The LOD was 74 (95% CI: 47-311) N. meningitidis copies. The LAMP-CRISPR/Cas performed well compared to the gold standard. In the 139 samples from suspected patients, the sensitivity and specificity of the test were 91% and 99% respectively. CONCLUSION: This developed and optimized method can complement for the available gold standard for the timely diagnosis of meningococcal meningitis and meningococcemia.

Ecotoxicity of the fluoroquinolone antibiotic delafloxacin to the water flea Simocephalus vetulus and its offspring under the influence of calcium modulation.

Delafloxacin (DFX), one of the latest additions to the fluoroquinolone antibiotics, is gaining heightened recognition in human therapy due to its potential antibacterial efficacy in a wide range of applications. Concerns have arisen regarding its presence in the environment and its potential interactions with multivalent metals, such as calcium (Ca). The present study investigated the trans- and multigenerational effects of environmentally projected concentrations of DFX (100-400 µg DFX L-1) on individual- and population-level responses of parental S. vetulus (F0) and its descendants (F1) under normal (26 mg L-1) and high (78 mg L-1) Ca conditions. Exposure of the F0 generation to DFX under the normal Ca condition resulted in reduced juvenile body length (JBL), increased age-specific survival rate (lx), indicating prolonged developmental time, reduced age-specific fecundity rate (mx), and decreased population growth rate (rm). Under the high Ca condition, JBL, mx, and rm were adversely affected. Transgenerational effects of DFX existed, as F1 individuals exhibited persistent suppressions in at least one endpoint under both Ca conditions even after being transferred to a clear medium. Continuous exposure of the F1 generation to DFX had negative impacts on JBL, mx, and rm under the normal Ca condition, and on JBL and rm under the high Ca condition. However, cumulative effects were not observed, suggesting the potential development of tolerance to DFX in the F1 organisms. These findings suggest that DFX is a harmful compound for the non-target model organism S. vetulus and reveal a potential antagonism between DFX and Ca. Nevertheless, the interaction between other (fluoro)quinolones and Ca remains unclear, necessitating further research to establish this phenomenon more comprehensively, including understanding the interaction mechanism in ecotoxicological contexts.

Insights into the epidemiology and clinical aspects of post-COVID-19 conditions in adult.

OBJECTIVES: While most individuals infected with COVID-19 recover completely within a few weeks, some continue to experience lingering symptoms. This study was conducted to identify and describe the clinical and subclinical manifestations of adult patients from the long-term effects of COVID-19. METHODS: The study analyzed 205 medical records of inpatients (age ≥ 16 years, ≥ 4 weeks post-COVID-19 recovery, and a negative SARS-CoV-2 status at enrollment) at Thong Nhat Hospital, Vietnam, from 6 September 2021 to 26 August 2022, using R language software. RESULTS: The majority of patients hospitalized with long COVID-19 symptoms (92.68%) had normal consciousness. The most common symptoms on admission were fatigue (59.02%), dyspnea (52.68%), and cough (42.93%). In total, 80% of patients observed respiratory symptoms, primarily dyspnea, while 42.44% reported neurological symptoms, with sleep disturbance being the most common. Noticeably, 42.93% of patients experienced respiratory failure in the post-COVID-19 period, resembling acute respiratory distress syndrome. DISCUSSION: These findings provide crucial insights into the epidemiology, clinical, and subclinical aspects of post-COVID-19 conditions, shedding light on the prevalence of common symptoms and the demographic distribution of affected patients. Understanding these manifestations is vital for patient well-being, improved clinical practice, and targeted healthcare planning, potentially leading to better patient care, management, and future interventions.

Toxicity of ciprofloxacin and ofloxacin to Moina macrocopa and investigation of p-value adjustments for (eco)toxicological studies.

Ciprofloxacin (CFX) and ofloxacin (OFX) are commonly found as residual contaminants in aquatic environments, posing potential risks to various species. To ensure the safety of aquatic wildlife, it is essential to determine the toxicity of these antibiotics and establish appropriate concentration limits. Additionally, in (eco)toxicological studies, addressing the issue of multiple hypothesis testing through p-value adjustments is crucial for robust decision-making. In this study, we assessed the no observed adverse effect concentration (NOAEC) of CFX and OFX on Moina macrocopa across a concentration range of 0-400 µg L-1. Furthermore, we investigated multiple p-value adjustments to determine the NOAECs. Our analysis yielded consistent results across seven different p-value adjustments, indicating NOAECs of 100 µg CFX L-1 for age at first reproduction and 200 µg CFX L-1 for fertility. For OFX treatment, a NOAEC of 400 µg L-1 was observed for both biomarkers. However, further investigation is required to establish the NOAEC of OFX at higher concentrations with greater certainty. Our findings demonstrate that CFX exhibits higher toxicity compared to OFX, consistent with previous research. Moreover, this study highlights the differential performance of p-value adjustment methods in terms of maintaining statistical power while controlling the multiplicity problem, and their practical applicability. The study emphasizes the low NOAECs for these antibiotics in the zooplanktonic group, highlighting their significant risks to ecological and environmental safety. Additionally, our investigation of p-value adjustment approaches contributes to a deeper understanding of their performance characteristics, enabling (eco)toxicologists to select appropriate methods based on their specific needs and priorities.

Unfractionated heparin versus enoxaparin for venous thromboembolism prophylaxis in intensive care units: a propensity score adjusted analysis.

Venous thromboembolism (VTE) is a common complication in hospitalized patients. Pharmacologic prophylaxis is used in order to reduce the risk of VTE events. The main purpose of this study is to compare the prevalence of deep vein thrombosis (DVT) and pulmonary embolism (PE) in patients admitted to the intensive care unit (ICU) who received unfractionated heparin (UFH) versus enoxaparin as VTE prophylaxis. Mortality was evaluated as a secondary outcome. This was a Propensity Score Adjusted Analysis. Patients admitted to neurology, surgical, or medical ICUs and screened with venous doppler ultrasonography or computed tomography angiography for detection of VTE were included in the analysis. We identified 2228 patients in the cohort, 1836 (82.4%) patients received UFH and 392 (17.6%) patients received enoxaparin. Propensity score matching yielded a well-balanced cohort of 950 (74% UFH, 26% enoxaparin) patients. After matching, there was no difference in prevalence of DVT (RR 1.05; 95% CI 0.67-1.64, p = 0.85) and PE (RR 0.76; 95% CI, 0.44-1.30, p = 0.31). No significant differences in location and severity of DVT and PE between the two groups were detected. Hospital and intensive care unit stay was similar between the two groups. Unfractionated heparin was associated with a higher rate of mortality, (HR 2.04; 95% CI, 1.13-3.70; p = 0.019). The use of UFH as VTE prophylaxis in ICU patients was associated with a similar prevalence of DVT and PE compared with enoxaparin, and the site and degree of occlusion were similar. However, a higher mortality rate was seen in the UFH group.

Two-stage revision for treatment of tuberculous prosthetic hip infection: an outcome analysis.

OBJECTIVES: Prosthetic joint infections (PJI) and especially tuberculosis (TB) PJI are rare diseases and hard to cure. The effectiveness of treatments for tuberculous PJI still remains a problem. The objective of this research was to indicate the success of two-stage revision replacement and also giving the associated criteria. METHODS: From 2015 to 2020, five patients with tuberculous PJI were treated with two-stage revision at Cho Ray hospital, Vietnam. We collected the dataset which included demographic data, the interval from the time of joint replacement to reported infection, records of tuberculous PJI, administration of anti-TB medications (duration, months), history of operation(s), duration of follow-up, and specific type(s) of antibiotics loaded in bone cement. The approval for this study was made by the institutional review board from Cho Ray Hospital, Vietnam. We conducted a literature review based on the keywords "PJI" and "TB" on PubMed. RESULTS: Five patients [median age 66 years (range 35-84)] had found tuberculous PJI. The median time from arthroplasty to diagnosis was 19 months (range 4-48). The diagnosis was confirmed by joint aspirates or synovial tissue. Positive PCR was also reported in all cases. The average duration of anti-tuberculosis polytherapy administration was 14.4 months. The operative techniques on five patients included debridement and using spacer loaded with 2 g streptomycin (and 2 g vancomycin if they got a coinfection) for 1 pack of bone cement, and revision arthroplasty. In most cases, the outcome of treatment using two-stage revision replacement was 80%. Overall, the auxiliary bacterial infections were recognized in three patients with tuberculous PJI and Staphylococcus aureus. Streptomycin and vancomycin were loaded in a cement spacer to increase the success rate, and tuberculous PJI was controlled for all patients. CONCLUSION: Tuberculous PJI can be controlled with two-stage revision replacement with an antibiotic-loaded cement spacer that is molded intraoperatively with custom mold and prolonged anti-tuberculosis treatment in all cases. LEVEL OF EVIDENCE: IV.

Optimization for a New XY Positioning Mechanism by Artificial Neural Network-Based Metaheuristic Algorithms.

This paper devotes a new method in modeling and optimizing to handle the optimization of the XY positioning mechanism. The fitness functions and constraints of the mechanism are formulated via proposing a combination of artificial neural network (ANN) and particle swarm optimization (PSO) methods. Next, the PSO is hybridized with the grey wolf optimization, namely PSO-GWO, which is applied to three scenarios in handling the single objective function. In order to search the multiple functions for the mechanism, the multiobjective optimization genetic algorithm (MOGA) is applied to the last scenario. The achieved results showed that the fitness functions are well-formulated using the PSO-based ANN method. In the scenario 1, the stroke achieved by the PSO-GWO (1852.9842 µm) is better than that gained from the GWO (1802.8087 µm). In the scenarios 2, the stress gained from the PSO-GWO (243.3183 MPa) is lower than that achieved from the GWO (245.0401 MPa). In the scenario 3, the safety factor retrieved from the PSO-GWO (1.9767) is greater than that achieved from the GWO (1.9278). In the scenario 4, by using MOGA, the optimal results found that the stroke is about (1741.3 µm) and the safety factor is 1.8929. The prediction results are well-fitted with the numerical and experimental verifications. The results of this paper are expected to facilitate the synthesis and analysis of compliant mechanisms and related engineering designs.

Design and Optimization for a New XYZ Micropositioner with Embedded Displacement Sensor for Biomaterial Sample Probing Application.

An XYZ compliant micropositioner has been widely mentioned in precision engineering, but the displacements in the X, Y, and Z directions are often not the same. In this study, a design and optimization for a new XYZ micropositioner are developed to obtain three same displacements in three axes. The proposed micropositioner is a planar mechanism whose advantage is a generation of three motions with only two actuators. In the design strategy, the proposed micropositioner is designed by a combination of a symmetrical four-lever displacement amplifier, a symmetrical parallel guiding mechanism, and a symmetrical parallel redirection mechanism. The Z-shaped hinges are used to gain motion in the Z-axis displacement. Four flexure right-circular hinges are combined with two rigid joints and two flexure leaf hinges to permit two large X-and-Y displacements. The symmetrical four-lever displacement amplifier is designed to increase the micropositioner's travel. The displacement sensor is built by embedding the strain gauges on the hinges of the micropositioner, which is developed to measure the travel of the micropositioner. The behaviors and performances of the micropositioner are modeled by using the Taguchi-based response surface methodology. Additionally, the geometrical factors of the XYZ micropositioner are optimized by teaching-learning-based optimization. The optimized design parameters are defined with an A of 0.9 mm, a B of 0.8 mm, a C of 0.57 mm, and a D of 0.7 mm. The safety factor gains 1.85, while the displacement achieves 515.7278 µm. The developed micropositioner is a potential option for biomedical sample testing in a nanoindentation system.

Predicting the risk of osteoporosis in older Vietnamese women using machine learning approaches.

Osteoporosis contributes significantly to health and economic burdens worldwide. However, the development of osteoporosis-related prediction tools has been limited for lower-middle-income countries, especially Vietnam. This study aims to develop prediction models for the Vietnamese population as well as evaluate the existing tools to forecast the risk of osteoporosis and evaluate the contribution of covariates that previous studies have determined to be risk factors for osteoporosis. The prediction models were developed to predict the risk of osteoporosis using machine learning algorithms. The performance of the included prediction models was evaluated based on two scenarios; in the first one, the original test parameters were directly modeled, and in the second the original test parameters were transformed into binary covariates. The area under the receiver operating characteristic curve, the Brier score, precision, recall and F1-score were calculated to evaluate the models' performance in both scenarios. The contribution of the covariates was estimated using the Permutation Feature Importance estimation. Four models, namely, Logistic Regression, Support Vector Machine, Random Forest and Neural Network, were developed through two scenarios. During the validation phase, these four models performed competitively against the reference models, with the areas under the curve above 0.81. Age, height and weight contributed the most to the risk of osteoporosis, while the correlation of the other covariates with the outcome was minor. Machine learning algorithms have a proven advantage in predicting the risk of osteoporosis among Vietnamese women over 50 years old. Additional research is required to more deeply evaluate the performance of the models on other high-risk populations.

Aetiologies and clinical presentation of central nervous system infections in Vietnamese patients: a prospective study.

Knowledge of the clinical presentation of central nervous system (CNS) infections and the causative pathogens is crucial for appropriate diagnosis and rapid initiation of appropriate treatment to prevent severe neurological sequelae. The aim of this study is to understand the aetiology of CNS infections based on the clinical presentation of Vietnamese patients. A prospective hospital-based cohort study was conducted between May 2014 and May 2017. We screened 137 patients with clinically suspected CNS infection for fungal, bacterial and viral pathogens using their cerebrospinal fluid (CSF) and blood cultures. In addition, DNA or RNA extracted from CSF samples were subjected to nucleic acid testing (NAT) with a selective panel of bacterial, viral and fungal pathogens. At least one pathogen could be detected in 41% (n = 56) of the patients. The main pathogens causing CNS infections were Streptococcus suis (n = 16; 12%) and Neisseria meningitidis (n = 9; 7%), followed by Herpes simplex virus 1/2 (n = 4; 3%) and Klebsiella pneumoniae (n = 4; 3%). Other pathogens were only identified in a few cases. Patients with bacterial CNS infections were significantly older, had a worse outcome, a lower Glasgow Coma Scale (GCS), a higher rate of speech impairment and neck stiffness than patients with viral or tuberculous CNS infections. In northern Vietnam, adults are mostly affected by bacterial CNS infections, which have a severe clinical course and worse outcomes compared to viral or tuberculous CNS infections. Clinicians should be aware of the regional occurrence of pathogens to initiate rapid and appropriate diagnosis and treatment.

Modeling and Optimization for a New Compliant 2-dof Stage for Locating Biomaterial Samples by an Efficient Approach of a Kinetostatic Analysis-Based Method and Neural Network Algorithm.

The nanoindentation technique is employed to characterize the behaviors of biomaterials. Nevertheless, there is a lack of development of a miniaturized precise positioner for in situ nanoindentation. Besides, modeling behaviors of the positioner are restricted due to its complex kinematic characteristics. Therefore, this paper proposes a novel compliant two degrees of freedom (dof) stage for positioning a biomaterial sample in in situ nanoindentation. In addition, a new modeling and dimensional optimization synthesis method of the stage is developed. The proposed effective methodology is developed based on a kinetostatic analysis-based calculation method, the Lagrange approach, and a neural network algorithm. With an increased advance in artificial intelligence, a neural network algorithm is proposed to extend the applicability of artificial neural networks in optimizing the parameters of the stage. First, the 2-dof stage is built via a combination of an eight-lever displacement amplifier and a symmetric parallelogram mechanism. Second, a chain of mathematical equations of the 2-dof stage is constructed using a kinetostatic analysis-based method to calculate the ratio of displacement amplification and the input stiffness of the 2-dof stage. Then, the Lagrange method is utilized to formulate the dynamic equation of the 2-dof stage. Finally, a neural network algorithm is adopted to maximize the natural first frequency of the proposed stage. The optimal results determined that the frequency of the stage can achieve a high value of 112.0995 Hz. Besides, the formed mathematical models were relatively precise by comprising the simulation verifications.

Diagnosis of pathogens causing bacterial meningitis using Nanopore sequencing in a resource-limited setting.

AIM: The aim of the present study is to compare the performance of 16S rRNA Nanopore sequencing and conventional culture in detecting infectious pathogens in patients with suspected meningitis in a resource-limited setting without extensive bioinformatics expertise. METHODS: DNA was isolated from the cerebrospinal fluid (CSF) of 30 patients with suspected bacterial meningitis. The isolated DNA was subjected to 16S sequencing using MinION™. The data were analysed in real time via the EPI2ME cloud platform. The Nanopore sequencing was done in parallel to routine microbiological diagnostics. RESULTS: Nanopore sequencing detected bacterial pathogens to species level in 13 of 30 (43%) samples. CSF culture showed 40% (12/30) positivity. In 21 of 30 patients (70%) with suspected bacterial meningitis, both methods yielded concordant results. About nine of 30 samples showed discordant results, of these five were false positive and four were false negative. In five of the culture negative results, nanopore sequencing was able to detect pathogen genome, due to the higher sensitivity of the molecular diagnostics. In two other samples, the CSF culture revealed Cryptococcus neoformans and Streptococcus pneumoniae, which were not detected by Nanopore sequencing. Overall, using both the cultures and 16S Nanopore sequencing, positivity rate increased from 40% (12/30) to 57% (17/30). CONCLUSION: Next-generation sequencing could detect pathogens within six hours and could become an important tool for both pathogen screening and surveillance in low- and middle-income countries (LMICs) that do not have direct access to extensive bioinformatics expertise.

CRISPR-Cas12a combination to alleviate the false-positive in loop-mediated isothermal amplification-based diagnosis of Neisseria meningitidis.

BACKGROUND: Loop isothermal amplification (LAMP) has recently been proposed as a point-of-care diagnostic tool to detect acute infectious pathogens; however, this technique embeds risk of generating false-positive results. Whereas, with abilities to accurately recognize specific sequence, the CRISPR/Cas12a can forms complexes with cognate RNA sensors and cleave pathogen's DNA targets complimerntary to its cognate RNA, afterward acquiring the collateral activity to unbiasedly cut nearby off-target fragments. Therefore, if relevant fluorescent-quencher-nucleic probes are present in the reaction, the non-specific cleavage of probes releases fluorescences and establish diagnostic read-outs. METHODS: The MetA gene of N. meningitidis was selected as target to optimize the LAMP reaction, whereas pseudo-dilution series of N. meningitidis gemonics DNA was used to establish the detection limit of LAMP/Cas12a combination assay. The diagnostic performance of established LAMP/Cas12a combination assay was validated in comparation with standard real-time PCR on 51 CSF samples (14 N. meningitidis confirmed patients and 37 control subjects). RESULTS: In relevant biochemical conditions, CRISPR-Cas12a and LAMP can work synchronously to accurately identify genetics materials of Nesseria menitigistis at the level 40 copies/reaction less than 2 h. CONCLUSIONS: In properly optimized conditions, the CRISPR-Cas12a system helps to alleviate false positive result hence enhancing the specificity of the LAMP assays.

Physiological response of Simocephalus vetulus to five antibiotics and their mixture under 48-h acute exposure.

Antibiotics, widely known as major environmental xenobiotics, are increasingly being released into ecosystems due to their essential functions in human health and production. During the COVID-19 pandemic waves, antibiotic use increases remarkably in treating bacterial coinfections. Antibiotics were initially expected only to affect prokaryotes, but recent research has shown that they can disturb the biological systems of eukaryotes, especially vulnerable aquatic creatures, through both direct and indirect processes. However, their toxicity to the freshwater cladoceran Simocephalus vetulus, an essential link in the aquatic food web, has never been evaluated. The effects of four fluoroquinolones (ciprofloxacin: CFX, ofloxacin: OFX, gatifloxacin: GFX, delafloxacin: DFX), tetracycline (TET), and a mixture of these medicines (MIX) on S. vetulus thoracic limb rate (TLR) were examined in this study. After S. vetulus was exposed to 20 and 40 mg GFX L-1, 90% and 100% mortality rates were recorded. At 2.5-10 mg L-1, GFX dramatically lowered the TLR of S. vetulus, resulting in a median effective concentration of 9.69 mg L-1. TLRs increased when the organisms were exposed to 10-40 mg L-1 of CFX and 1.25-40 mg L-1 of OFX. However, DFX and TET exposures did not affect TLRs. Exposure to MIX reduced TLR only at 40 mg L-1, suggesting an antagonistic interaction among the five pharmaceuticals. This study demonstrated that S. vetulus physiological responses to antibiotics, even in the same class, are complex and elusive. Beyond a common additive concentration principle, the antagonistic interaction of antibiotic mixture indicates a high level of uncertainty in terms of ecological dangers. We initially introduce S. vetulus to ecotoxicological studies of antibiotics, presenting the species as a low-cost model for physiological investigations of environmental xenobiotics.

Does eutrophication enhance greenhouse gas emissions in urbanized tropical estuaries?

Estuaries are considered as important sources of the global emission of greenhouse gases (GHGs). Urbanized estuaries often experience eutrophication under strong anthropogenic activities. Eutrophication can enhance phytoplankton abundance, leading to carbon dioxide (CO2) consumption in the water column. Only a few studies have evaluated the relationship between GHGs and eutrophication in estuaries. In this study, we assessed the concentrations and fluxes of CO2, methane (CH4) and nitrous oxide (N2O) in combination with a suite of biogeochemical variables in four sampling campaigns over two years in a highly urbanized tropical estuary in Southeast Asia (the Saigon River Estuary, Vietnam). The impact of eutrophication on GHGs was evaluated through several statistical methods and interpreted by biological processes. The average concentrations of CO2, CH4 and N2O at the Saigon River in 2019-2020 were 3174 ± 1725 µgC-CO2 L-1, 5.9 ± 16.8 µgC-CH4 L-1 and 3.0 ± 4.8 µgN-N2O L-1, respectively. Their concentrations were 13-18 times, 52-332 times, and 9-37 times higher than the global mean concentrations of GHGs, respectively. While CO2 concentration had no clear seasonal pattern, N2O and CH4 concentrations significantly differed between the dry and the rainy seasons. The increase in eutrophication status along the dense urban area was linearly correlated with the increase in GHGs concentrations. The presence of both nitrification and denitrification resulted in elevated N2O concentrations in this urban area of the estuary. The high concentration of CO2 was contributed by the high concentration of organic carbon and mineralization process. GHGs fluxes at the Saigon River Estuary were comparable to other urbanized estuaries regardless of climatic condition. Control of eutrophication in urbanized estuaries through the implantation of efficient wastewater treatment facilities will be an effective solution in mitigating the global warming potential caused by estuarine emissions.