Development of a gold nanoparticle-based lateral flow immunoassay for the fast detection of diafenthiuron in cabbage and apples.

Due to its unique insecticidal and acaricidal mechanism of action, and ability to mix with most insecticides and fungicides, diafenthiuron (DIAF) is widely used in the cultivation of fruits and vegetables. However, this insecticide can cause unacceptable harm to organisms, making the detection of DIAF residues in fruits and vegetables crucial. In this study, a novel hapten based on the structure of DIAF was utilized to prepare a monoclonal antibody (mAb) with high specificity and sensitivity. The half maximum inhibitory concentration (IC50) of the anti-DIAF mAb was 20.96 µg kg-1 as determined by ic-ELISA and little cross-reactivity with other analogues. Next, a GNP-based lateral flow immunoassay (LFIA) was developed to detect DIAF in cabbages and apples. The optimized LFIA, for cabbage samples, showed a visual limit of detection (vLOD), cut-off value and calculated limit of detection (cLOD) of 0.1 mg kg-1, 10 mg kg-1 and 1.5 µg kg-1, respectively, and for apples 0.1 mg kg-1, 5 mg kg-1 and 3.4 µg kg-1, respectively. Recovery rates in cabbage and apples were 89.4-105.0% and 105.3-112.0%, with a coefficient of variation of 2.73-5.71% and 2.15-7.56%, respectively. These results indicated that the established LFIA based on our anti-DIAF mAb was a reliable method for in situ rapid detection of DIAF in cabbage and apple samples.

A gold nanoparticle based colorimetric sensor for the rapid detection of Yersinia enterocolitica serotype O:8 in food samples.

Foodborne diseases caused by Yersinia enterocolitica serotype O:8 represent global public health problems. We need rapid Y. enterocolitica O:8 detection methods to ensure food safety. In this study, we developed a colloidal gold-based immunochromatographic strip test (ICST) for the rapid detection of Y. enterocolitica O:8. A sandwich detection format was applied to Y. enterocolitica O:8 detection, where a monoclonal antibody (mAb) labeled with colloidal gold and mAb immobilized on the test line were used as the capture antibody and detection antibody, respectively. The limit of detection of the colloidal gold ICST was 1.3 × 103, 3.0 × 102 and 8.0 × 102 CFU mL-1 for Y. enterocolitica O:8 CICC 21669, CICC 21681 and CICC 21567, respectively. The method developed by us had no cross-reactivity with other foodborne pathogens. Using ICST, we detected Y. enterocolitica O:8 strains at a low level (5 CFU mL-1) in milk and pork samples after 4 h and 6 h of separate incubation. The results were obtained within 10 min without sophisticated instruments. Therefore, the colloidal gold ICST is an accurate and sensitive method for the detection of Y. enterocolitica O:8 in food samples.

An immunochromatographic sensor for ultrasensitive and direct detection of histamine in fish.

To ensure food quality and prevent histamine (HA) toxicity, a rapid and direct method of detecting HA is required. In this work, we prepared a monoclonal antibody (mAb) against HA using a hapten produced by the introduction of a phenyl-containing linker. The novel mAb exhibited high sensitivity against HA as determined by ELISA, with a half-maximal inhibitory concentration of 21.51 ng/mL. A gold nanoparticle-based immunosensor was fabricated for rapid detection of HA in fish samples. After optimizing the immunosensor, a visual limit of detection (LOD) and a calculated LOD were 0.25 mg/kg and 10.48 µg/kg for HA, respectively. Recovery rates from the spiked fish samples ranged from 87.33% to 104.67% with the coefficient of variation below 10.82%. Concurrently, the whole process in testing real sample was completed within 15 min, and all results were well confirmed and comparable by liquid chromatography-mass spectrometry and the commercial test strip. These data revealed that the proposed immunosensor could be used as a monitoring tool for the rapid and direct detection of HA in fish samples.

Gold nanoparticle-based immunochromatographic assay for detection Pseudomonas aeruginosa in water and food samples.

Pseudomonas aeruginosa (P. aeruginosa) is the common infection-causing bacterial pathogen. Conventional methods for the detection of P. aeruginosa are time-consuming, and therefore, a more rapid analytical method is required. Here, monoclonal antibodies (Mabs) against P. aeruginosa (CICC 10419) were prepared and based on paired Mabs, an immunochromatographic assay (ICA) was developed. The ICA strip showed a limit of detection of 2.41 × 104 CFU/mL and the linear range of detection was 3.13 × 104-1.0 × 106 CFU/mL. No cross-reactivity was observed when other common Gram-negative and Gram-positive bacteria were used. The analytical performance of the ICA strip indicated that the developed ICA had good specificity and stability. Moreover, the feasibility of the ICA strip was verified by detecting P. aeruginosa (CICC 10419) in spiked water and food samples. The ICA strip could detect samples contaminated with a low-level of P. aeruginosa (CICC 10419) after 8 h enrichment.

Sensitive detection of RNA based on concatenated self-fuelled strand displacement amplification and hairpin-AgNCs.

Herein, a self-fuelled amplification strategy (SFAS) is proposed, in which two strand displacement amplification (SDA) processes were concatenated for the proliferation of ssDNA. The ssDNA then initiated a polymerase action and caused the destruction of hairpin-templated silver nanoclusters (AgNCs), resulting in decreased fluorescence for sensing miRNA-21. This SFAS-based sensor is less complicated in design and facile in operation, because of the easy concatenation of SDA and mutual enzymes used in the signal output process. The sensitivity of this SFAS-based miRNA sensor was 1.78 × 10-11 M with a linear relationship in the range 0.02-1.0 × 10-9 M, and the recoveries of this method ranged from 82.07% to 106.58% with an average RSD of 10.96%.

Synergistical accumulation for electrochemical sensing of 1-hydroxypyrene on electroreduced graphene oxide electrode.

A graphene modified glassy carbon electrode was fabricated for sensitive and convenient electrochemical detection of 1-hydroxypyrene (1-OHP). The graphene modified electrode was prepared by eletrochemical reduction of graphene oxide on glass carbon electrode. l-OHP was synergistically accumulated on the graphene modified electrode via π-π conjugate adsorption and electrochemical oxidation. Electrochemical behavior of l-OHP on the graphene modified glass carbon electrode was studied in detail. The developed method gave a linear calibration curve for the determination of 1-OHP in the range of 5-300 nM (R2 = 0.997), a limit of detection of 0.84 nM (S/N = 3). The proposed method was also successfully applied to the analysis of urine samples for l-OHP with the recoveries of 97.3-101.1%.

Assessing the Public Health Impact and Effectiveness of Interventions To Prevent Salmonella Contamination of Sprouts.

Sprouts have been a recurring public health challenge due to microbiological contamination, and Salmonella has been the major cause of sprout-associated outbreaks. Although seed treatment and microbiological testing have been applied as risk reduction measures during sprout production, the extent to which their effectiveness in reducing the public health risks associated with sprouts has not been well investigated. We conducted a quantitative risk assessment to measure the risk posed by Salmonella contamination in sprouts and to determine whether and how mitigation strategies can achieve a satisfactory risk reduction based on the assumption that the risk reduction achieved by a microbiological sampling and testing program at a given sensitivity is equivalent to that achieved by direct inactivation of pathogens. Our results indicated that if the sprouts were produced without any risk interventions, the health impact caused by sprouts contaminated with Salmonella would be very high, with a median annual estimated loss of disability-adjusted life years (DALYs) of 691,412. Seed treatment (with 20,000 ppm of calcium hypochlorite) or microbiological sampling and testing of spent irrigation water (SIW) alone could reduce the median annual impact to 734 or 4,856 DALYs, respectively. Combining seed treatment with testing of the SIW would further decrease the risk to 58 DALYs. This number could be dramatically lowered to 3.99 DALYs if sprouts were produced under conditions that included treating seeds with 20,000 ppm of calcium hypochlorite plus microbiological testing of seeds, SIW, and finished products. Our analysis shows that the public health impact due to Salmonella contamination in sprouts could be controlled if seeds are treated to reduce pathogens and microbiological sampling and testing is implemented. Future advances in intervention strategies would be important to improve sprout safety further.

Behavior of Shiga toxigenic Escherichia coli relevant to lettuce washing processes and consideration of factors for evaluating washing process surrogates.

Postharvest processes for fresh produce commonly include washing in water containing antimicrobial chemicals, such as chlorine; however, if the antimicrobials are not present in sufficient levels, washing can promote the spread of contamination that might be present. To understand cross-contamination risk during washing, we tested a collection of Shiga toxigenic Escherichia coli (STEC), including O157:H7 and other non-O157 strains, for certain traits during washing of fresh-cut lettuce, i.e., sensitivity to sublethal chlorine levels and ability to cross-contaminate (detach from and attach to) lettuce in the presence of sublethal chlorine levels. Nonpathogenic E. coli Nissle 1917 (EcN) and Pediococcus pentosaceus lactic acid bacterial species (LAB) were included as potential washing process validation surrogates. As measured by extension of the lag phase of growth in media containing 0.15 ppm of chlorine, chlorine sensitivity varied among the STECs. Cross-contamination was assessed by evaluating transfer of bacteria from inoculated to uninoculated leaves during washing. Without chlorine, similar transfer to wash water and uninoculated leaves was shown. In 1 ppm of chlorine, cross-contamination was not detected with most strains, except for the substantial transfer by a STEC O111 strain and EcN in some replicates. Strain O111 and EcN showed less inactivation in 0.25 ppm of chlorine water compared with O157 (P < 0.05). LAB showed similar transfer and similar chlorine inactivation to O157. Considering together the sublethal chlorine sensitivity and detachment/attachment traits, neither EcN nor LAB displayed optimal characteristics as washing process surrogates for the STEC strains, although further evaluation is needed. This work demonstrated a range of behaviors of STEC strains during lettuce washing and may be helpful in hazard characterization, identifying factors to consider for evaluating washing process efficacy, and identifying phenotypic traits to select surrogates to validate washing processes.

[Simultaneous determination of monosaccharides, disaccharides, oligosaccharides and sugar alcohols in foods by high performance liquid chromatography with evaporative light-scattering detection].

A simple and efficient method was established based on high performance liquid chromatography (HPLC) to separate and detect thirteen analytes of monosaccharides, disaccharides, oligosaccharides and sugar alcohols (xylose, fructose, glucose, sucrose, maltose, lactose, 1-kestose, nystose, 1F-fructofuranosyl nystose, erythritol, mannitol, xylitol, maltitol) in foods. The separation was performed on an NH2 column with the gradient elution of acetonitrile-water as the mobile phases. The analytes were detected by an evaporative light-scattering detector (ELSD). All the thirteen sugars had good linearities within 0.1 - 5 g/L with the correlation coefficients between 0.9901 - 0.9996. The limits of detection (LOD) were all less than 0.1 g/L. The precisions of the method expressed as RSDs were in the range of 2.69% -7.21%. The recoveries of the thirteen analytes spiked in real samples ranged from 96.1% to 105.2%. This method was applied to the actual sample testings and the results showed the food labels were greatly different from the actual compositions.

Unrecognized vitamin D3 deficiency is common in Parkinson disease: Harvard Biomarker Study.

OBJECTIVE: To conclusively test for a specific association between the biological marker 25-hydroxy-vitamin D3, a transcriptionally active hormone produced in human skin and liver, and the prevalence and severity of Parkinson disease (PD). METHODS: We used liquid chromatography/tandem mass spectrometry to establish an association specifically between deficiency of 25-hydroxy-vitamin D3 and PD in a cross-sectional and longitudinal case-control study of 388 patients (mean Hoehn and Yahr stage of 2.1 ± 0.6) and 283 control subjects free of neurologic disease nested in the Harvard Biomarker Study. RESULTS: Plasma levels of 25-hydroxy-vitamin D3 were associated with PD in both univariate and multivariate analyses with p values = 0.0034 and 0.047, respectively. Total 25-hydroxy-vitamin D levels, the traditional composite measure of endogenous and exogenous vitamin D, were deficient in 17.6% of patients with PD compared with 9.3% of controls. Low 25-hydroxy-vitamin D3 as well as total 25-hydroxy-vitamin D levels were correlated with higher total Unified Parkinson's Disease Rating Scale scores at baseline and during follow-up. CONCLUSIONS: Our study reveals an association between 25-hydroxy-vitamin D3 and PD and suggests that thousands of patients with PD in North America alone may be vitamin D-deficient. This finding has immediate relevance for individual patients at risk of falls as well as public health, and warrants further investigation into the mechanism underlying this association.

Microbial contamination in sprouts: how effective is seed disinfection treatment?

Microbial contamination of sprouts by Salmonella and Escherichia coli O157 : H7 has been a common cause of foodborne diseases and a continuing challenge to the sprout industry. Seed disinfection treatment has been recommended as a major intervention step in a multihurdle approach to reduce the risk of illness associated with contaminated sprouts. U.S. Food and Drug Administration cited 20000 ppm calcium hypochlorite as an example treatment in its recommendation for seed treatment and this treatment has been considered the reference standard for seed disinfection treatment for over a decade. However, promising new disinfection treatments have emerged in recent years. In this study, we summarized published data and compared the efficacies of different disinfection methods in the reduction of microbial contamination on seeds. Our findings suggest that while biological interventions such as competitive exclusion and certain chemical treatments appear to be similar to 20000 ppm calcium hypochlorite for seed disinfection, physical methods especially high pressure may be more effective than the reference standard regardless of the type of bacteria or seed. The combination of 2 or more treatments, sequentially or simultaneously, may further improve disinfection results. Since treatments with high levels of chemical disinfectants, especially 20000 ppm calcium hypochlorite, can pose environmental and worker safety risks, alternative intervention approaches should be considered. Additional studies to confirm the greater efficacy of certain physical and combined seed disinfection treatments and to identify other effective management strategies are needed to further improve sprout safety.

Transcriptional modulator H2A histone family, member Y (H2AFY) marks Huntington disease activity in man and mouse.

Huntington disease (HD) is a progressive neurodegenerative disease that affects 30,000 individuals in North America. Treatments that slow its relentless course are not yet available, and biomarkers that can reliably measure disease activity and therapeutic response are urgently needed to facilitate their development. Here, we interrogated 119 human blood samples for transcripts associated with HD. We found that the dynamic regulator of chromatin plasticity H2A histone family, member Y (H2AFY) is specifically overexpressed in the blood and frontal cortex of patients with HD compared with controls. This association precedes the onset of clinical symptoms, was confirmed in two mouse models, and was independently replicated in cross-sectional and longitudinal clinical studies comprising 142 participants. A histone deacetylase inhibitor that suppresses neurodegeneration in animal models reduces H2AFY levels in a randomized phase II clinical trial. This study identifies the chromatin regulator H2AFY as a potential biomarker associated with disease activity and pharmacodynamic response that may become useful for enabling disease-modifying therapeutics for HD.

Association of SNCA with Parkinson: replication in the Harvard NeuroDiscovery Center Biomarker Study.

BACKGROUND: Mutations in the α-synuclein gene (SNCA) cause autosomal dominant forms of Parkinson's disease, but the substantial risk conferred by this locus to the common sporadic disease has only recently emerged from genome-wide association studies. METHODS: We genotyped a prioritized noncoding variant in SNCA intron 4 in 344 patients with Parkinson's disease and 275 controls from the longitudinal Harvard NeuroDiscovery Center Biomarker Study. RESULTS: The common minor allele of rs2736990 was associated with elevated disease susceptibility (odds ratio, 1.40; P = .0032). CONCLUSIONS: This result increases confidence in the notion that in many clinically well-characterized patients, genetic variation in SNCA contributes to "sporadic" disease.

Design of functional small interfering RNAs targeting amyotrophic lateral sclerosis-associated mutant alleles.

BACKGROUND: RNA interference (RNAi) is a potential cure for amyotrophic lateral sclerosis (ALS) caused by dominant, gain-of-function superoxide dismutase 1 (SOD1) mutations. The success of such therapy relies on the functional small interfering RNAs (siRNAs) that can effectively deliver RNAi. This study aimed to design the functional siRNAs targeting ALS-associated mutant alleles. METHODS: A modified dual luciferase system containing human SOD1 mRNA target was established to quantify siRNA efficacy. Coupled with validated siRNAs identified in the literature, we analyzed the rationale of siRNA design and subsequently developed an asymmetry rule-based strategy for designing siRNA. We then further tested the effectiveness of this design strategy in converting a naturally symmetric siRNA into functional siRNAs with favorable asymmetry for gene silencing of SOD1 alleles. RESULTS: The efficacies of siRNAs could vary tremendously by one base-pair position change. Functional siRNAs could target the whole span of SOD1 mRNA coding sequence as well as non-coding region. While there is no distinguishable pattern of the distribution of nucleobases in these validated siRNAs, the high percent of GC count at the last two positions of siRNAs (P18 and P19) indicated a strong effect of asymmetry rule. Introducing a mismatch at position 1 of the 5' of antisense strand of siRNA successfully converted the inactive siRNA into functional siRNAs that silence SOD1 with desired efficacy. CONCLUSIONS: Asymmetry rule-based strategy that incorporates a mismatch into siRNA most consistently enhances RNAi efficacy and guarantees producing functional siRNAs that successfully silence ALS-associated SOD1 mutant alleles regardless target positions. This strategy could also be useful to design siRNAs for silencing other disease-associated dominant, gain-of-function mutant genes.

Prevention of coronary artery disease in men: male hormone, female hormone, or both?

Sex hormones play an important role in coronary artery disease. Although both male and female hormones have been well-documented to be able to influence vascular biology, the preventive use of sex hormones in CAD is not established. Recent progress suggests a necessity of rethinking of the use of sex hormones for CAD in both sexes. We hypothesize that a long-term and appropriate low-dose combination of male hormone and female hormone could be an effective preventive strategy for men with a high risk of but not developed CAD. This hypothesis is supported by the fact that estrogen has favorable profiles on several key CAD-associated risk factors regardless of sexes. Testosterone supplementation has been linked to a reduced risk of CAD specifically in men. In animal models the reduced risk of CAD in males administrated with testosterone is due to the conversion of testosterone into estrogen; and sex hormone ratio changes rather than each individual sex hormone were found to be the predictor of CAD in a human study, suggesting the importance of a proper ratio of estrogen:testosterone in the development of CAD. In addition, the controversy surrounding the use of hormone replacement therapy in women in turn indicates a potential beneficial effect of sex hormones in men in the prevention of CAD because of the fundamental difference between sexes. Therefore, the combined use of estrogen and testosterone for CAD in men deserves a full investigation and could provide useful information in understanding of the preventive and/or therapeutic application of sex hormones in both sexes.

Changes of procedural learning in Chinese patients with non-demented Parkinson disease.

To study procedural learning changes in patients with non-demented Parkinson disease (PD) but without depression. The Nissen serial reaction time task (SRTT) software version II (as a task of procedural learning), the Wechsler Memory Scale-Chinese version (WMS-CR), and two tasks of implicit memory were applied to 20 PD patients with a Hoehn-Yahr score at I-II degrees and 20 matched healthy controls were enrolled for the Nissen Version test. In the explicit WMS-CR and the implicit (word stem completion and degraded picture naming) tasks, the patients' scores fell within normal limits. In the SRTT, healthy controls displayed significantly reduced response times and error rates across the blocks of repeated sequence trials. In contrast, PD patients only showed a reduction in error rates but no change in response times. Impairment of nigrostriatal pathways selectively affects the performance in visuo-motor learning tasks such as the SRTT, but not in both the explicit tasks of WMS-CR and the implicit tasks.

Stress-associated poor health among adult immigrants with a language barrier in the United States.

The healthy migrant hypothesis supported by the 'Hispanic paradox' suggests that immigrants are healthier than non-immigrants. To test the generalizability of this hypothesis, we studied the stress-associated health status of adult immigrants with a language barrier in the USA. Three stress-related conditions (Unhappiness, Depression, and Anxiety) and self-reported health status were ascertained from participants of the Community Tracking Study Health Survey conducted in 2003. The associations between these conditions as well as the immigrants' length of time living in the USA and health were assessed. Our results demonstrated that the three stress-related conditions were significantly associated with a dramatically elevated poor health status (Unhappiness: OR = 5.22, 95% CI: 4.43-6.14; Depression: OR = 3.03, 95% CI: 2.31-3.98; Anxiety: OR = 5.12, 95% CI: 3.53-7.41). Compared to US citizens without a language barrier, immigrants with a language barrier were more likely to report poor health (OR = 2.15, 95% CI: 1.66-2.78). After adjustment for stressors, the likelihood of reporting poor health among immigrants with a language barrier decreased significantly (OR = 1.75, 95% CI: 1.05-2.91). In addition, these immigrants were more likely to report poor health within the first 10 years of their living in the USA (

Is coronary artery disease a multifactorial inherited disorder with a sex-influenced trait?

The genetic linkage of coronary artery disease is well-established. However, the transmission of this disease is not clearly defined. Although the Mendelian autosomal dominant pattern has been seen in familial hypercholesterolemia and mutant MEF2A induced familiar myocardial infarction, and a multifactorial genetic model has been proposed for non-familial CAD, the gender difference in this disease is not well explained. We hypothesized that CAD is a multifactorial inherited disorder with a sex-influenced trait, which shows an autosomal dominant pattern in men and autosomal recessive transmission in women. This hypothesis is supported by the facts including an age-dependent higher prevalence in men, the autosomal locations of CAD associated genes, the gender difference seen even in familiar CAD, and the potential gene-gene interactions between CAD associated genes on autosomal chromosomes and those found on the X chromosome. Further investigation of genetic components will provide not only the critical information about the etiology of CAD, but also help to clarify the confusion in the use of exogenous female hormones in the prevention and/or the treatment of the disease.

Alzheimer's disease: epidemiology, genetics, and beyond.

Alzheimer's disease (AD) is an increasing epidemic threatening public health. Both men and women are susceptible to the disease although women are at a slightly higher risk. The prevalence of AD rises exponentially in elderly people from 1% at age of 65 to approximately 40%-50% by the age of 95. While the cause of the disease has not been fully understood, genetics plays a role in the onset of the disease. Mutations in three genes (APP, PSEN1, and PSEN2) have been found to cause AD and APOE4 allele increases the risk of the disease. As human genomic research progresses, more genes have been identified and linked with AD. Genetic screening tests for persons at high risk of AD are currently available and may help them as well as their families better prepare for a later life with AD.