The responsiveness of renewable energy production to geopolitical risks, oil market instability and economic policy uncertainty: Evidence from United States.

This paper aims to investigate the responsiveness of renewable energy production (REP) to fluctuations in geopolitical risks, oil prices and economic policy uncertainty (EPU). It applies a cross-quantilogram framework to examine monthly data of the US economy for the period of 1986-2022. The findings illustrate the asymmetric effect of historical geopolitical risk (GPRH) on REP under long memory. The findings also hold after different subcategories of GPRH, including geopolitical threats and geopolitical acts, are considered. A positive shock in GPRH has the most decisive positive impact on REP when the policies are driven by both energy security and environmental commitments. A positive shock in GPRH can negatively impact REP when policies are driven by energy security causes only. EPU exerts strong negative effects on REP in bearish and bullish states of the market under medium and long memory across different measures of EPU. Dynamic connectedness analysis applying TVP-VAR method between pairwise variables indicates that net REP is a volatility receiver to the changes in GPRH, its subcomponents, oil prices and different measures of EPU.

Association between diet soft drink consumption and metabolic dysfunction-associated steatotic liver disease: findings from the NHANES.

BACKGROUND: Lifestyle change plays a crucial role in the prevention and treatment of metabolic dysfunction-associated steatotic liver disease (MASLD). In recent years, diet soft drinks that emphasize "zero sugar and zero calories" have become all the rage, but whether diet soft drink consumption is associated with MASLD is not clear. METHODS: This study included data from the National Health and Nutrition Examination Surveys (NHANES) in 2003-2006. The assessment of MASLD status primarily relied on the Fatty Liver Index (FLI). Weighted multiple Logistic regression models were constructed to evaluate the association between diet soft drink consumption and MASLD. Additionally, mediation analysis was performed to examine the mediating effect of body mass index (BMI). RESULTS: A total of 2,378 participants were included in the study, among which 1,089 individuals had MASLD, and the weighted prevalence rate was 43.64%. After adjusting for variables related to demographic, lifestyle, and metabolic syndrome, excessive diet soft drink consumption (the "always" frequency) remained significantly associated with the occurrence of MASLD (OR = 1.98, 95%CI = 1.36-2.89, P = 0.003). It was estimated that 84.7% of the total association between diet soft drink consumption and MASLD was mediated by BMI (P < 0.001). CONCLUSIONS: Excessive diet soft drink consumption was associated with the occurrence of MASLD. BMI may play a mediating role in the association between diet soft drink consumption and MASLD.

Multi-Modal Feature Fusion-Based Multi-Branch Classification Network for Pulmonary Nodule Malignancy Suspiciousness Diagnosis.

Detecting and identifying malignant nodules on chest computed tomography (CT) plays an important role in the early diagnosis and timely treatment of lung cancer, which can greatly reduce the number of deaths worldwide. In view of the existing methods in pulmonary nodule diagnosis, the importance of clinical radiological structured data (laboratory examination, radiological data) is ignored for the accuracy judgment of patients' condition. Hence, a multi-modal fusion multi-branch classification network is constructed to detect and classify pulmonary nodules in this work: (1) Radiological data of pulmonary nodules are used to construct structured features of length 9. (2) A multi-branch fusion-based effective attention mechanism network is designed for 3D CT Patch unstructured data, which uses 3D ECA-ResNet to dynamically adjust the extracted features. In addition, feature maps with different receptive fields from multi-layer are fully fused to obtain representative multi-scale unstructured features. (3) Multi-modal feature fusion of structured data and unstructured data is performed to distinguish benign and malignant nodules. Numerous experimental results show that this advanced network can effectively classify the benign and malignant pulmonary nodules for clinical diagnosis, which achieves the highest accuracy (94.89%), sensitivity (94.91%), and F1-score (94.65%) and lowest false positive rate (5.55%).

On the relationship between pollution reduction and export product quality: Evidence from Chinese firms.

Chinese government adopted a new environmental program during "Eleventh Five-Year Plan" period. Whether this program can achieve its goal of pollution reduction and quality improvement for exports is of vital importance for China's sustainable development. This paper constructs a quasi-difference-in-difference (DID) framework to identify the effects of the new environmental policy on export product quality by using highly disaggregated trade transaction data at the product level. Empirical results show that the implementation of pollution reduction targets is negatively correlated with export product quality. This negative impact is more profound in western regions, capital-intensive industries, privately owned firms and firms exporting to countries which are not members of Organization for Economic Co-operation and Development group. In addition, our extended analysis shows that the negative effects can be mitigated through product switching within the firms. The major policy implication is that local governments should take proper measures to strengthen the effects of innovation offsets caused by environmental regulation and effectively utilize the induced effects of environmental regulation on product switching. The goal is to achieve a win-win outcome for environmental protection and improvement in export product quality.

Efficacy of artemether-lumefantrine for treating uncomplicated Plasmodium falciparum cases and molecular surveillance of drug resistance genes in Western Myanmar.

BACKGROUND: Currently, artemisinin-based combination therapy (ACT) is the first-line anti-malarial treatment in malaria-endemic areas. However, resistance in Plasmodium falciparum to artemisinin-based combinations emerging in the Greater Mekong Sub-region is a major problem hindering malaria elimination. To continuously monitor the potential spread of ACT-resistant parasites, this study assessed the efficacy of artemether-lumefantrine (AL) for falciparum malaria in western Myanmar. METHODS: Ninety-five patients with malaria symptoms from Paletwa Township, Chin State, Myanmar were screened for P. falciparum infections in 2015. After excluding six patients with a parasite density below 100 or over 150,000/µL, 41 P. falciparum patients were treated with AL and followed for 28 days. Molecular markers associated with resistance to 4-amino-quinoline drugs (pfcrt and pfmdr1), antifolate drugs (pfdhps and pfdhfr) and artemisinin (pfk13) were genotyped to determine the prevalence of mutations associated with anti-malarial drug resistance. RESULTS: For the 41 P. falciparum patients (27 children and 14 adults), the 28-day AL therapeutic efficacy was 100%, but five cases (12.2%) were parasite positive on day 3 by microscopy. For the pfk13 gene, the frequency of NN insert after the position 136 was 100% in the day-3 parasite-positive group as compared to 50.0% in the day-3 parasite-negative group, albeit the difference was not statistically significant (P = 0.113). The pfk13 K189T mutation (10.0%) was found in Myanmar for the first time. The pfcrt K76T and A220S mutations were all fixed in the parasite population. In pfmdr1, the Y184F mutation was present in 23.3% of the parasite population, and found in both day-3 parasite-positive and -negative parasites. The G968A mutation of pfmdr1 gene was first reported in Myanmar. Prevalence of all the mutations in pfdhfr and pfdhps genes assessed was over 70%, with the exception of the pfdhps A581G mutation, which was 3.3%. CONCLUSIONS: AL remained highly efficacious in western Myanmar. Pfk13 mutations associated with artemisinin resistance were not found. The high prevalence of mutations in pfcrt, pfdhfr and pfdhps suggests high-degree resistance to chloroquine and antifolate drugs. The pfmdr1 N86/184F/D1246 haplotype associated with selection by AL in Africa reached > 20% in this study. The detection of > 10% patients who were day-3 parasite-positive after AL treatment emphasizes the necessity of continuously monitoring ACT efficacy in western Myanmar.

Consumer-perceived risks of genetically modified food in China.

This paper analyses the factors influencing consumer-perceived risks of genetically modified (GM) food by using a structural equation model and survey data of urban residents in China. The sample is divided into the acquainted and unacquainted groups according to consumers' objective knowledge level. An integrated analytical framework is developed. The results show that consumers' positive attitude towards GM technology has a significant negative effect on consumer-perceived risks and that more information reaching consumers significantly reduces consumer-perceived risks of GM food only for the unacquainted group. Consumers' trust in government, biotechnology scientists, press media and food companies does not significantly influence consumer-perceived risks of GM food. This is likely because consumers have low trust in the abovementioned stakeholders of GM food. Consumers think that the information reaching them is limited and does not clearly show the advantages and disadvantages of GM food. Consumers' objective knowledge of GM food is also limited. The health risks of GM food are of high concern for both consumer groups. These findings imply that the commercialization of GM crops in China is dependent on providing consumers with adequate and understandable information about GM food and strict supervision measures for food safety.

Association of CYP17A1 Genetic Polymorphisms and Susceptibility to Essential Hypertension in the Southwest Han Chinese Population.

BACKGROUND The CYP17A1 gene encodes for cytochrome P450 enzyme CYP17A1, which is involved with the steroidogenic pathway including mineralocorticoids. The CYP17A1 polymorphisms might affect enzyme activity, then leading to a state of mineralocorticoid 11-deoxycorticosterone excess characterized by hypertension, suppressed plasma renin activity, and low aldosterone concentrations. The aim of this study was to investigate the contribution of CYP17A1 polymorphisms in inducing the susceptibility to essential hypertension among the Southwest Han Chinese population. MATERIAL AND METHODS Eight single nucleotide polymorphisms of CYP17A1 were genotyped in a case-control study for samples by polymerase chain reaction-restriction fragment length polymorphism analysis. RESULTS The polymorphisms rs11191548 and rs4919687 were significantly associated with hypertension risk, which was confirmed by systolic and diastolic blood pressure distribution analyses between different genotype groups, and these two polymorphisms were found in linkage disequilibrium. The rs4919687 polymorphism was estimated to cause the destruction of exonic splicing silencer (ESR and Motif 3) sites and to transform the transcription factor AREB6 binding site, respectively, in the bioinformatics analyses. The haplotypes rs4919686A-rs3740397G -rs4919687C-rs743572C-rs11191548C and rs4919686A-rs3740397G-rs4919687T-rs743572C- rs11191548T were found to be susceptible to essential hypertension. CONCLUSIONS Our findings suggest that the CYP17A1 polymorphisms could be a genetic risk factor for essential hypertension among the Yunnan Han Chinese population, which would have implications for the treatment of this complex disorder.

Genetic diversity of the Pvk12 gene in Plasmodium vivax from the China-Myanmar border area.

BACKGROUND: Plasmodium falciparum resistance to artemisinin emerged in the Greater Mekong Sub-region has been associated with mutations in the propeller domain of the kelch gene Pfk13. METHODS: Here the polymorphisms in Pvk12 gene, the orthologue of Pfk13 in Plasmodium vivax, were determined by PCR and sequencing in 262 clinical isolates collected in recent years (2012-2015) from the China-Myanmar border area. RESULTS: Sequencing of full-length Pvk12 genes from these isolates identified three synonymous mutations (N172N, S360S, S697S) and one non-synonymous mutation M124I, all of which were at very low prevalence (2.0-3.1%). Moreover, these mutations were non-overlapping between the two study sites on both sides of the border. Molecular evolutionary analysis detected signature of purifying selection on Pvk12. CONCLUSIONS: There is no direct evidence that Pvk12 is involved in artemisinin resistance in P. vivax, but it remains a potential candidate requiring further investigation. Continuous monitoring of potential drug resistance in this parasite is needed in order to facilitate the regional malaria elimination campaign.

Artemisinin resistance at the China-Myanmar border and association with mutations in the K13 propeller gene.

Artemisinin resistance in Plasmodium falciparum parasites in Southeast Asia is a major concern for malaria control. Its emergence at the China-Myanmar border, where there have been more than 3 decades of artemisinin use, has yet to be investigated. Here, we comprehensively evaluated the potential emergence of artemisinin resistance and antimalarial drug resistance status in P. falciparum using data and parasites from three previous efficacy studies in this region. These efficacy studies of dihydroartemisinin-piperaquine combination and artesunate monotherapy of uncomplicated falciparum malaria in 248 P. falciparum patients showed an overall 28-day adequate clinical and parasitological response of >95% and day 3 parasite-positive rates of 6.3 to 23.1%. Comparison of the 57 K13 sequences (24 and 33 from day 3 parasite-positive and -negative cases, respectively) identified nine point mutations in 38 (66.7%) samples, of which F446I (49.1%) and an N-terminal NN insertion (86.0%) were predominant. K13 propeller mutations collectively, the F446I mutation alone, and the NN insertion all were significantly associated with day 3 parasite positivity. Increased ring-stage survival determined using the ring-stage survival assay (RSA) was highly associated with the K13 mutant genotype. Day 3 parasite-positive isolates had ∼10 times higher ring survival rates than day 3 parasite-negative isolates. Divergent K13 mutations suggested independent evolution of artemisinin resistance. Taken together, this study confirmed multidrug resistance and emergence of artemisinin resistance in P. falciparum at the China-Myanmar border. RSA and K13 mutations are useful phenotypic and molecular markers for monitoring artemisinin resistance.

[Association of CMA1 gene tag single nucleotide polymorphisms with essential hypertension in Yi population from Yunnan].

OBJECTIVE: To assess the association of tag single nucleotide polymorphisms (tag SNPs) of chymase gene (CMA1) with essential hypertension in Yi population from Yunnan, China. METHODS: A case-control study was carried out. Four tag SNPs(rs1956921, rs1800876, rs5244 and rs1885108) were genotyped in 303 patients with essential hypertension and 312 healthy controls using polymerase chain reaction - restriction fragment length polymorphism(PCR-RFLP) method. RESULTS: No significant difference in genotypic and allelic distributions of the four polymorphisms was detected between the two groups(P>0.05), and the same results existed in the females. The frequencies of rs1956921 C allele and a C-T haplotype constructed with rs1956921 and rs5244 were greater in male patients compared with male controls(P<0.01). CONCLUSION: The rs1956921 C allele of the CMA1 gene and the C-T haplotype constructed with rs1956921 and rs5244 may be risk factors for essential hypertension in ethnic Yi males from Yunnan.

Based on Weighted Gene Co-Expression Network Analysis Reveals the Hub Immune Infiltration-Related Genes Associated with Ulcerative Colitis.

Purpose: Immune infiltration plays a pivotal role in the pathogenesis of mucosal damage in ulcerative colitis (UC). The objective of this study was to systematically analyze and identify genetic characteristics associated with immune infiltration in UC. Patients and Methods: Gene expression data from three independent datasets obtained from the Gene Expression Omnibus (GEO) were utilized. By employing the ssGSEA and CIBERSORT algorithms, we estimated the extent of immune cell infiltration in UC samples. Subsequently, Weighted Correlation Network Analysis (WGCNA) was performed to identify gene modules exhibiting significant associations with immune infiltration, and further identification of hub genes associated with immune infiltration was accomplished using least absolute shrinkage and selection operator (LASSO) regression analysis. The relationship between the identified hub genes and clinical information was subsequently investigated. Results: Our findings revealed significant activation of both innate and adaptive immune cells in UC. Notably, the expression levels of CD44, IL1B, LYN, and ITGA5 displayed strong correlations with immune cell infiltration within the mucosa of UC patients. Immunohistochemical analysis confirmed the significant upregulation of CD44, LYN, and ITGA5 in UC samples, and their expression levels were found to be significantly associated with common inflammatory markers, including the systemic immune inflammation indices, C-reactive protein, and erythrocyte sedimentation rate. Conclusion: CD44, LYN, and ITGA5 are involved in the immune infiltration pathogenesis of UC and may be potential therapeutic targets for UC.

Global burden and risk factors of gastritis and duodenitis: an observational trend study from 1990 to 2019.

In recent years, there has been a global trend of aging, which has resulted in significant changes to the burden of gastritis and duodenitis (GD). Using the global burden of disease (GBD) database spanning 1990 to 2019, we evaluated the temporal trends of age-standardized incidence rates (ASIR), age-standardized death rates (ASDR), and age-standardized disability-adjusted life years (AS-DALYs) for GD using estimated annual percentage changes (EAPC). Additionally, we examined the burden of GD across various strata, including social demographic index (SDI), age, and sex. Finally, the risk factors linked to the incidence and mortality of GD, utilizing Pearson correlation analysis. In 2019, there were 31 million GD patients globally, a notable increase of 12 million from 1990, while the ASIR, ASDR, and AS-DALYs for GD all showed a decrease. Correlation analysis showed a significant negative relationship between ASIR and SDI. Factors like hand hygiene and vitamin A deficiency had significant positive correlations with ASIR and ASDR in 2019. Over the past thirty years, the burden of GD has increased alongside global population aging. Future efforts should focus on exploring prevention for GD, with special attention to the elderly population in low SDI regions.

Acetyl-CoA Synthetase Mutations S868G and V949I Do Not Confer Resistance to Antimalarial Drugs in vitro in Plasmodium falciparum.

Plasmodium falciparum acetyl-CoA synthetase (PfACAS) protein is an important source of acetyl-CoA. We detected the mutations S868G and V949I in PfACAS by whole-genome sequencing analysis in some recrudescent parasites after antimalarial treatment with artesunate and dihydroartemisinin-piperaquine, suggesting that they may confer drug resistance. Using CRISPR/Cas9 technology, we engineered parasite lines carrying the PfACAS S868G and V949I mutations in two genetic backgrounds and evaluated their susceptibility to antimalarial drugs in vitro. The results demonstrated that PfACAS S868G and V949I mutations alone or in combination were not enough to provide resistance to antimalarial drugs.

Absence of association between Pfnfs1 mutation and in vitro susceptibility to lumefantrine in Plasmodium falciparum.

Artemether-lumefantrine (AL) is the most widely used antimalarial drug for treating uncomplicated falciparum malaria. This study evaluated whether the K65Q mutation in the Plasmodium falciparum cysteine desulfurase IscS (Pfnfs1) gene was associated with alternated susceptibility to lumefantrine using clinical parasite samples from Ghana and the China-Myanmar border area. Parasite isolates from the China-Myanmar border had significantly higher IC50 values to lumefantrine than parasites from Ghana. In addition, the K65 allele was significantly more prevalent in the Ghanaian parasites (34.5%) than in the China-Myanmar border samples (6.8%). However, no difference was observed in the lumefantrine IC50 value between the Pfnfs1 reference K65 allele and the non reference 65Q allele in parasites from the two regions. These data suggest that the Pfnfs1 K65Q mutation may not be a reliable marker for reduced susceptibility to lumefantrine.

Adjunctive therapeutic effects of micronutrient supplementation in inflammatory bowel disease.

Growing evidence suggests that micronutrient status may have some impact on the course of inflammatory bowel disease (IBD). However, micronutrient deficiencies are easily overlooked during the treatment of IBD patients. There have been many studies on micronutrient supplementation, in which several clinical trials have been conducted targeting vitamin D and iron, but the current research is still preliminary for other vitamins and minerals. This review provides an overview of the adjunctive therapeutic effects of micronutrient supplementation in IBD, to summarize the available evidence, draw the attention of clinicians to micronutrient monitoring and supplementation in patients with IBD, and also provide some perspectives for future research directions.

Association of Dietary Fiber, Composite Dietary Antioxidant Index and Risk of Death in Tumor Survivors: National Health and Nutrition Examination Survey 2001-2018.

BACKGROUND: Dietary fiber is a functional substance with strong antioxidant activity that plays an important role in human health. Dietary fiber has been shown to reduce the risks of many types of cancers, but whether it can reduce the risk of death in cancer survivors remains undetermined. METHODS: This study included the dietary data of cancer survivors who participated in the National Health and Nutrition Examination Surveys from 2001 to 2018. Firstly, the relationship between fiber intake and composite dietary antioxidant index (CDAI) was explored by weighted multiple regression and smooth curve. Subsequently, multivariable Cox proportional hazards regression models were used to explore the effects of dietary fiber intake and CDAI level on the risks of all-cause, tumor, and cardiovascular death among cancer survivors. RESULTS: A total of 2077 participants were included in the study, representing approximately 11,854,509 cancer survivors in the United States. The dietary fiber intake of tumor survivors had a nonlinear positive relationship with CDAI levels (ß = 0.24, 95% CI: 0.08-0.40, p = 0.004). Multivariable Cox proportional hazards regression models showed that high dietary fiber intake and CDAI levels were associated with reduced risks of all-cause and tumor death in tumor survivors, but were not associated with the risk of cardiovascular death. CONCLUSION: An increased dietary fiber intake can enhance the body's antioxidant capacity. A higher dietary fiber intake and CDAI level may reduce the risk of all-cause and tumor death in tumor survivors.

Trends in Oxidative Balance Score and Prevalence of Metabolic Dysfunction-Associated Steatotic Liver Disease in the United States: National Health and Nutrition Examination Survey 2001 to 2018.

BACKGROUND: Most studies have primarily focused on assessing the association between diet or exercise patterns and metabolic dysfunction-associated steatotic liver disease (MASLD). This study adopted a more comprehensive approach by introducing the oxidative balance score (OBS) to evaluate the combined effects of diet and lifestyle on the body's antioxidant ability. Our main objective was to investigate the association between OBS and the burden of MASLD in the United States. METHODS: Participants with complete information from 2001 to 2018 were included. In the absence of other definite liver injury factors, the United States fatty liver index (us-FLI) ≥ 30 was used as the diagnostic criterion for MASLD. We first calculated the weighted prevalence for each cycle and stratified it according to demographic and metabolic-related disease characteristics. Subsequently, weighted multiple logistic regression was used to evaluate the relationship between OBS and MASLD. In addition, we explored the body's inflammatory state and the level of insulin resistance (IR) in mediating OBS and MASLD. RESULTS: From 2001 to 2018, the prevalence of MASLD in the U.S. population as a whole increased from 29.76% to 36.04%, and the rate was higher in people with metabolic-related diseases. Notably, OBS exhibited a negative correlation with MASLD. Participants in the highest tertile of OBS had a significantly lower prevalence of MASLD compared to those in the lowest tertile [OR: 0.72, 95%CI: (0.57, 0.92), p < 0.001]. Moreover, a high OBS is associated with a lower inflammatory state and level of IR. The body's inflammatory state and IR level mediated the association between OBS and MASLD by 5.2% and 39.7%, respectively (both p < 0.001). CONCLUSIONS: In this study, we observed an increasing prevalence of MASLD over the years. A higher OBS was associated with a lower risk of MASLD, especially when OBS ≥ 25. The body's inflammatory state and IR level mediate the association between OBS and MASLD, but the mechanism needs to be further investigated.

A simple alkali lysis method for Plasmodium falciparum DNA extraction from filter paper blood samples.

A fast, simple, easy, efficient, and inexpensive method for DNA extraction from malaria parasites collected on filter paper would be very useful for molecular surveillance. The quality and quantity of DNA are critical to molecular diagnosis and analysis. Here, we developed a simple alkali lysis method for DNA extraction from blood samples on filter paper. The results showed that 10-50 mM NaOH and deionized water all effectively isolated parasite DNA at higher parasitemia, as witnessed by successful PCR amplification, while at a parasitemia of 0.01%, the 10 mM NaOH lysis condition generated the best results. Furthermore, DNA extracted by this method was successfully used to amplify a fragment of > 2000 bp. This method successfully extracted DNA from 1 µl of blood at a parasitemia as low as 0.0001% (equivalent to 5 parasites /µl). The DNA isolated by the 10 mM NaOH lysis method was stable to yield PCR products after storage at 4 °C or - 20 °C for 12 months. These results indicate that this alkali lysis method is simple, effective, sensitive, and inexpensive for isolating stable Plasmodium DNA from dried blood spots on filter paper.

Genetic diversity of Plasmodium vivax populations from the China-Myanmar border identified by genotyping merozoite surface protein markers.

BACKGROUND: Parasite diversity and population structure influence malaria control measures. Malaria transmission at international borders affects indigenous residents and migrants, defying management efforts and resulting in malaria re-introduction. Here we aimed to determine the extent and distribution of genetic variations in Plasmodium vivax populations and the complexity of infections along the China-Myanmar border. METHODS: We collected clinical P. vivax samples from local and migrant malaria patients from Laiza and Myitsone, Kachin State, Myanmar, respectively. We characterized the polymorphisms in two P. vivax merozoite surface protein markers, Pvmsp-3α and Pvmsp-3ß, by PCR-restriction fragment length polymorphism (PCR-RFLP) analysis. We sought to determine whether these genetic markers could differentiate these two neighboring parasite populations. RESULTS: PCR revealed three major size variants for Pvmsp-3α and four for Pvmsp-3ß among the 370 and 378 samples, respectively. PCR-RFLP resolved 26 fragment-size alleles by digesting Pvmsp-3α with Alu I and Hha I and 28 alleles by digesting Pvmsp-3ß with Pst I. PCR-RFLP analysis of Pvmsp-3α found that infections in migrant laborers from Myitsone bore more alleles than did infections in residents of Laiza, while such difference was not evident from genotyping Pvmsp-3ß. Infections originating from these two places contained distinct but overlapping subpopulations of P. vivax. Infections from Myitsone had a higher multiplicity of infection as judged by the size of the Pvmsp-3α amplicons and alleles after Alu I/Hha I digestion. CONCLUSIONS: Migrant laborers from Myitsone and indigenous residents from Laiza harbored overlapping but genetically distinct P. vivax parasite populations. The results suggested a more diverse P. vivax population in Myitsone than in the border town of Laiza. PCR-RFLP of Pvmsp-3α offers a convenient method to determine the complexity of P. vivax infections and differentiate parasite populations.

Application of a low-cost, specific, and sensitive loop-mediated isothermal amplification (LAMP) assay to detect Plasmodium falciparum imported from Africa.

BACKGROUND: Chinese citizens traveling abroad bring back imported malaria cases to China. Current malaria diagnostic tests, including microscopy and antigen-detecting rapid tests, cannot reliably detect low-density infections. To complement existing diagnostic methods, we aimed to develop a new loop-mediated isothermal amplification (LAMP) assay to detect and identify Plasmodium falciparum in Chinese travelers returning from Africa. METHODS: We developed a miniaturized LAMP assay to amplify the actin I gene of P. falciparum. Each reaction consumed only 25% of the reagents used in a conventional LAMP assay and the same amount of DNA templates used in nested PCR. We evaluated this LAMP assay's performance and compared it to microscopy and a nested PCR assay using 466 suspected malaria cases imported from Africa. We assessed the sensitivity of the new LAMP assay using cultured P. falciparum, clinical samples, and a plasmid construct, allowing unprecedented precision when quantifying the limit of detection. RESULTS: The new LAMP assay was highly sensitive and detected two more malaria cases than nested PCR. Compared to nested PCR, the sensitivity and specificity of the novel LAMP assay were 100% [95% confidence interval (CI) 98.5-100%] and 99.1% (95% CI 96.7-99.9%), respectively. When evaluated using serial dilutions of the plasmid construct, the detection limit of the new LAMP was as low as 102 copies/µL, 10-fold lower than PCR. The LAMP assay detected 0.01 parasites/µL of blood (equal to 0.04 parasites/µL of DNA) using cultured P. falciparum and 1-7 parasites/µL of blood (4-28 parasites/µL of DNA) in clinical samples, which is as good as or better than previously reported and commercially licensed assays. CONCLUSION: The novel LAMP assay based on the P. falciparum actin I gene was specific, sensitive, and cost-effective, as it consumes 1/4 of the reagents in a typical LAMP reaction.