Recent methods and biosensors for foodborne pathogen detection in fish: progress and future prospects to sustainable aquaculture systems.

The aquaculture industry has advanced toward sustainable recirculating systems, in where parameters of food quality are strictly monitored. Despite that, as in the case of conventional aquaculture practices, the recirculating systems also suffer threats from Aeromonas spp., Vibrio spp., Streptococcus spp., among other foodborne pathogens infecting farmed fish. The aquaculture pathogens are routinely detected by conventional PCR methods or antibody-based tests, with the detection protocols confined to laboratory use. Emerging assay technologies and biosensors recently reported in the literature open new opportunities to the development of sensitive, specific, and portable analytical devices to use in the field. Techniques of DNA/RNA analysis, immunoassays and other nanomolecular technologies have been facing important advances in response time, sensitivity, and enhanced power of discrimination among and within species. Moreover, the recent developments of electrochemical and optical signal transduction have facilitated the incorporation of the innovative assays to practical miniaturized devices. In this work, it is provided a critical review over foodborne pathogen detection by existing and promising methods and biosensors applied to fish samples and extended to other food matrices. While isothermal DNA/RNA amplification methods can be highlighted among the assay methods for their promising analytical performance and suitability for point-of-care testing, the electrochemical transduction provides a way to achieve cost-effective biosensors amenable to use in the aquaculture field. The adoption of new methods and biosensors would constitute a step forward in securing sustainable aquaculture systems.

A Fluorescence Sensing Method with Reduced DNA Typing and Low-Cost Instrumentation for Detection of Sample Tampering Cases in Urinalysis.

This work presents a method to unequivocally detect urine sample tampering in cases where integrity of the sample needs to be verified prior to urinalysis. The technique involves the detection of distinct patterns of a triplex short tandem repeats system in DNA extracted from human urine. The analysis is realized with single-dye fluorescence detection and using a regular smartphone camera. The experimental results had demonstrated the efficacy of the analytical approach to obtaining distinct profiles of amplicons in urine from different sample providers. Reproducibility tests with fresh and stored urine have revealed a maximum variation in the profiles within an interval of 5 to 9%. Cases of urine sample tampering via mixture were simulated in the study, and the experiments have identified patterns of mixed genotypes from dual mixtures of urine samples. Moreover, sample adulteration by mixing a non-human fluid with urine in a volume ratio over 25% can be detected. The low cost of the approach is accompanied by the compatibility of the technique to use with different DNA sample preparation protocols and PCR instrumentation. Furthermore, the possibility of realizing the method in an integrated microchip system open great perspectives to conducting sample integrity tests at the site of urine sample reception and/or at resource-limited settings.

Design and characterisation of a graphene-based FET for ultrasensitive detection of clinical biomarkers.

The high demand for point-of-care devices for the convenient detection and follow-up of chronic diseases is posing demands to the development of novel low-cost sensors. The chronic obstructive pulmonary disease (COPD) is one of the most worldwide spread diseases, due to cigarette smoking and air pollution. Owing to the unstable and spontaneous characteristics of this disease is essential to have a sensitive, rapid, and easy-to-use device for the detection of diseases biomarkers. The research of emerging materials such as graphene monolayer and perovskite may revolutionise the field of point-of-care devices. These materials can boost the sensitivity and specificity of the detection, and therefore the detection can be performed in samples taken non-invasively, such saliva, and with less sample quantity. A graphene field effect transistor (GFET) coated with PEDOT:PSS and perovskite, bring advantages to the photodetection field, due to the unique proprieties of 2D materials and the structure of perovskite. This work presents a study of material characteristics comprising a GFET, with perspective to detect biomarkers of COPD.

The Role of Temperature, Ammonia and Nitrite to bioluminescence of Aliivibrio fischeri: towards a new sensor for aquaculture.

Recirculating Aquaculture Systems (RAS) present an innovative, clean and practical way of producing fish intensively. Stress caused by high concentrations of chemical species such as nitrite and un-ionized ammonia, affects fish health and growth and therefore the sustainability of RAS would require an online monitoring for those chemical stressors. This work reveals a study on the suitability of Aliivibrio fischeri as a toxicity sensor for un-ionized ammonia and nitrite. Temperature variation effects were also considered. An EC50 of 0.17 mg/L was found for nitrite and 0.57 mg/L for un-ionized ammonia. It was concluded that Allivibrio fischeri is suitable as an indicator for nitrite in aquaculture at optimal salinity and temperature conditions.

Monitoring Aquaculture Water Quality: Design of an Early Warning Sensor with Aliivibrio fischeri and Predictive Models.

A novel toxicity-warning sensor for water quality monitoring in recirculating aquaculture systems (RAS) is presented. The design of the sensor system mainly comprises a whole-cell biosensor. Aliivibrio fischeri, a luminescent bacterium widely used in toxicity analysis, was tested for a mixture of known fish-health stressors, namely nitrite, un-ionized ammonia, copper, aluminum and zinc. Two toxicity predictive models were constructed. Correlation, root mean squared error, relative error and toxic behavior were analyzed. The linear concentration addition (LCA) model was found suitable to ally with a machine learning algorithm for prediction of toxic events, thanks to additive behavior near the limit concentrations for these stressors, with a root-mean-squared error (RMSE) of 0.0623, and a mean absolute error of 4%. The model was proved to have a smaller relative deviation than other methods described in the literature. Moreover, the design of a novel microfluidic chip for toxicity testing is also proposed, which is to be integrated in a fluidic system that functions as a bypass of the RAS tank to enable near-real time monitoring. This chip was tested with simulated samples of RAS water spiked with zinc, with an EC50 of 6,46E-7 M. Future work will be extended to the analysis of other stressors with the novel chip.

Profiling a multiplex short tandem repeat loci from human urine with use of low cost on-site technology for verification of sample authenticity.

This work focuses on the development of a sophisticated technique via STR typing to unequivocally verify the authenticity of urine samples before sent to laboratories. STR profiling was conducted with the CSF1PO, TPOX, TH01 Multiplex System coupled with a smartphone-based detection method. The promising capability of the method to identify distinct STR profiles from urine of different persons opens the possibility to conduct sample authenticity tests. On-site STR profiling could be realized with a self-contained autonomous device with an integrated PCR microchip shown hereby.

Highly sensitive detection of human cancer antigens by an immunogold-silver assay chip coupled with a polythiophene-based optical sensor.

This work presents a novel method for protein or cancer antigen detection in clinical samples by an immunogold-silver assay microfluidic biochip coupled with a polythiophene-based organic photodetector. The method has showed a detection limit below 1ng/mL and the low cost and high sensitivity of both organic photodetector and immunogold-silver assay make this method amenable for realization in a portable handheld probe tip biosensor.

Polycarbazole-based organic photodiodes for highly sensitive chemiluminescent immunoassays.

It is reported the development of a polycarbazole-based organic photodetector for chemiluminescent immunoassays. The optical detector comprised a 1∶4 blend by weight of poly [N-9'-heptadecanyl-2,7-carbazole-alt-5,5-(4',7'-di-2-thienyl-2',1',3'-benzothiadiazole)] (PCDTBT) and [6,6]-phenyl C71-butyric acid methyl ester (PC70BM). Optimization of the photodetector design was conducted aiming to maximize photosensitivity and reduce the background level. Quantitation of recombinant human thyroid stimulating hormone indicated good linearity and yielded a detection sensitivity of ∼3.7 nA × nM(-1) and a detection limit of 80 pg/ml.

Detection of stress hormones by a microfluidic-integrated polycarbazole/fullerene photodetector.

A novel photodetector integrated microfluidic system for chemiluminescence (CL) detection is reported. The system incorporates a polycarbazole/fullerene photodiode whose optical characteristics (i.e. dark current, external quantum efficiency and photosensitivity) are described here. Using a CL immunoassay for detecting the stress hormone cortisol, the integrated photodetector achieved a detection sensitivity of 1.775 pA × nM(-1) and a detection limit of less than 0.28 nM. The device would be a powerful low-cost alternative to silicon photodiode and photomultiplier tube for bioanalytical assays, with potentially wide-ranging applications within point-of-care diagnostics.

An infrared radiation based thermal biosensor for enzymatic biochemical reactions.

In this paper, a thermal biosensor based on the infrared radiation energy is proposed for calorimetric measurement of biochemical reactions. Having a good structure design combined with MEMS technology as well as employing the Si /SiGe quantum well sensing material with a high TCR and low 1/f noise, the sensor shows potentials to be high sensitive and real-time. The urea enzymatic reaction was tested to verify the performance of sensor, which demonstrates a linear detection range from 0.5mM to 150mM and a relative standard deviation less than 1%. For the sensor fabrication, wafer-level transfer bonding is a key process, which makes the integration of quantum well material and a free standing structure possible. It reduces the heat loss from the sensor to the surrounding environment.

6-mercaptopurine inhibits atherosclerosis in apolipoprotein e*3-leiden transgenic mice through atheroprotective actions on monocytes and macrophages.

OBJECTIVE: 6-Mercaptopurine (6-MP), the active metabolite of the immunosuppressive prodrug azathioprine, is commonly used in autoimmune diseases and transplant recipients, who are at high risk for cardiovascular disease. Here, we aimed to gain knowledge on the action of 6-MP in atherosclerosis, with a focus on monocytes and macrophages. METHODS AND RESULTS: We demonstrate that 6-MP induces apoptosis of THP-1 monocytes, involving decreased expression of the intrinsic antiapoptotic factors B-cell CLL/Lymphoma-2 (Bcl-2) and Bcl2-like 1 (Bcl-x(L)). In addition, we show that 6-MP decreases expression of the monocyte adhesion molecules platelet endothelial adhesion molecule-1 (PECAM-1) and very late antigen-4 (VLA-4) and inhibits monocyte adhesion. Screening of a panel of cytokines relevant to atherosclerosis revealed that 6-MP robustly inhibits monocyte chemoattractant chemokine-1 (MCP-1) expression in macrophages stimulated with lipopolysaccharide (LPS). Finally, local delivery of 6-MP to the vessel wall, using a drug-eluting cuff, attenuates atherosclerosis in hypercholesterolemic apolipoprotein E*3-Leiden transgenic mice (P<0.05). In line with our in vitro data, this inhibition of atherosclerosis by 6-MP was accompanied with decreased lesion monocyte chemoattractant chemokine-1 levels, enhanced vascular apoptosis, and reduced macrophage content. CONCLUSIONS: We report novel, previously unrecognized atheroprotective actions of 6-MP in cultured monocytes/macrophages and in a mouse model of atherosclerosis, providing further insight into the effect of the immunosuppressive drug azathioprine in atherosclerosis.

Vitamin D receptor: a new risk marker for clinical restenosis after percutaneous coronary intervention.

OBJECTIVE: Restenosis is the main drawback of percutaneous coronary intervention (PCI). Inherited factors may explain part of the risk of restenosis. Recently, the vitamin D receptor (VDR) has been shown to be involved not only in bone metabolism but also in modulating immune responses and cell proliferation. Since the inflammatory response is implicated in restenosis, VDR-gene variants could therefore contribute to the risk of restenosis. METHODS/RESULTS: Systematic genotyping for 15 haplotype tagging single-nucleotide polymorphisms (SNPs) of the VDR gene was performed with the high throughput TaqMan allelic discrimination assays in the Genetic Determinants of Restenosis (GENDER) population. A haplotype-based survival analysis revealed an association of haplotypes in blocks 2, 3 and 4 of the VDR-gene with the risk of clinical restenosis (p-values 0.01, 0.04 and 0.02 respectively). After adjustment for clinical risk factors for restenosis, the individual effect of the block 2 AA haplotype (p = 0.011) persisted. CONCLUSIONS: The present study indicates that VDR plays a role in restenosis after PCI. Therefore, VDR genotype may be used as risk marker for restenosis and may contribute to individual patient screening prior to PCI in clinical practice.

The influence of established genetic variation in the haemostatic system on clinical restenosis after percutaneous coronary interventions.

Since activation of the haemostatic system is an important feature of the wound healing response triggered by arterial injury, variations in genes involved in thrombus formation may play a role in restenosis after percutaneous coronary interventions (PCI). Therefore, our aim was to examine the relationship between polymorphisms that are known to play a role in the haemostatic system and the risk of clinical restenosis in the GENetic DEterminants of Restenosis (GENDER) study, a multicenter prospective study design that enrolled 3,104 consecutive patients after successful PCI. Target vessel revascularization (TVR) was the primary endpoint. All patients were genotyped for six polymorphisms in the Factor II, Factor V, Factor VII and PAI-1 genes. The PAI-1 4G variant was associated with an increased risk of TVR. When compared to 5G/5G homozygotes, heterozygous patients were at higher risk for TVR (HR: 1.46, 95% CI: 1.05-2.03), whereas patients with the 4G/4G genotype had an even further increased risk (HR: 1.69, 95% CI: 1.19-2.41). In contrast, the factor V 506Gln (factor V Leiden) amino acid substitution was associated with a decreased risk of TVR (HR: 0.41, 95% CI: 0.19-0.86). Our findings indicate that polymorphisms in the factorV and PAI-1 genes may play a role in the process of restenosis.

Apolipoprotein C-I is crucially involved in lipopolysaccharide-induced atherosclerosis development in apolipoprotein E-knockout mice.

BACKGROUND: Lipopolysaccharide (LPS), which is released from gram-negative bacteria on multiplication or lysis, aggravates atherosclerosis in humans and rodents by inducing inflammation via toll-like receptors. Because apolipoprotein C-I (apoCI) enhances the LPS-induced inflammatory response in macrophages in vitro and in mice, we investigated the effect of endogenous apoCI expression on LPS-induced atherosclerosis in mice. METHODS AND RESULTS: Twelve-week-old apoe-/- apoc1-/- and apoe-/- apoc1+/+ mice received weekly intraperitoneal injections of LPS (50 microg) or vehicle for a period of 10 weeks, and atherosclerosis development was assessed in the aortic root. LPS administration did not affect atherosclerotic lesion area in apoe-/- apoc1-/- mice but increased it in apoe-/- apoc1+/+ mice. In fact, apoCI expression increased the LPS-induced atherosclerotic lesion area by 60% (P<0.05), concomitant with an increase in LPS-induced plasma levels of fibrinogen and E-selectin. This indicated that apoCI increased the LPS-induced inflammatory state, both systemically (ie, fibrinogen) and at the level of the vessel wall (ie, E-selectin). In addition, both macrophage-derived apoCI and HDL-associated apoCI increased the LPS-induced tumor necrosis factor-alpha response by macrophages in vitro. CONCLUSIONS: We conclude that apoCI is crucially involved in LPS-induced atherosclerosis in apoe-/- mice, which mainly relates to an increased inflammatory response toward LPS. We anticipate that apoCI plasma levels contribute to accelerated atherosclerosis development in individuals who have chronic infection.

Sirolimus and paclitaxel provoke different vascular pathological responses after local delivery in a murine model for restenosis on underlying atherosclerotic arteries.

BACKGROUND: Drug-eluting stents (DES) have been introduced successfully in clinical practice to prevent post-angioplasty restenosis. Nevertheless, concerns about the safety of DES still exist. OBJECTIVE: To investigate the vascular pathology and transcriptional responses to sirolimus and paclitaxel in a murine model for restenosis on underlying diseased atherosclerotic arteries. METHODS: Atherosclerotic lesions were induced by placement of a perivascular cuff around the femoral artery of hypercholesterolaemic ApoE*3-Leiden transgenic mice. Two weeks later these cuffs were replaced either by sirolimus- or paclitaxel-eluting cuffs. The vascular pathological effects were evaluated after two additional weeks. RESULTS: Both anti-restenotic compounds significantly inhibited restenotic lesion progression on the atherosclerotic plaques. Vascular histopathological analyses showed that local delivery of sirolimus has no significant adverse effects on vascular disease. Conversely, high dosages of paclitaxel significantly increased apoptosis, internal elastic lamina disruption, and decreased medial and intimal smooth muscle cells and collagen content. Moreover, transcriptional analysis by real-time RT-PCR showed an increased level of pro-apoptotic mRNA transcripts (FAS, BAX, caspase 3) in paclitaxel-treated arteries. CONCLUSIONS: Sirolimus and paclitaxel are effective in preventing restenosis. Sirolimus has no significant effect on arterial disease. In contrast, paclitaxel at high concentration demonstrated adverse vascular pathology and transcriptional responses, suggesting a narrower therapeutic range of this potent drug. Since the use of overlapping stents is becoming more common in DES technology, this factor is important, given that higher dosages of paclitaxel may lead to increased apoptosis in the vessel wall and, consequently, to a more unstable phenotype of the pre-existing atherosclerotic lesion.

Activation of nuclear receptor Nur77 by 6-mercaptopurine protects against neointima formation.

BACKGROUND: Restenosis is a common complication after percutaneous coronary interventions and is characterized by excessive proliferation of vascular smooth muscle cells (SMCs). We have shown that the nuclear receptor Nur77 protects against SMC-rich lesion formation, and it has been demonstrated that 6-mercaptopurine (6-MP) enhances Nur77 activity. We hypothesized that 6-MP inhibits neointima formation through activation of Nur77. METHODS AND RESULTS: It is demonstrated that 6-MP increases Nur77 activity in cultured SMCs, which results in reduced [3H]thymidine incorporation, whereas Nur77 small interfering RNA knockdown partially restores DNA synthesis. Furthermore, we studied the effect of 6-MP in a murine model of cuff-induced neointima formation. Nur77 mRNA is upregulated in cuffed arteries, with optimal expression after 6 hours and elevated expression up to 7 days after vascular injury. Local perivascular delivery of 6-MP with a drug-eluting cuff significantly inhibits neointima formation in wild-type mice. Locally applied 6-MP does not affect inflammatory responses or apoptosis but inhibits expression of proliferating cell nuclear antigen and enhances protein levels of the cell-cycle inhibitor p27(Kip1) in the vessel wall. An even stronger inhibition of neointima formation in response to local 6-MP delivery was observed in transgenic mice that overexpressed Nur77. In contrast, 6-MP does not alter lesion formation in transgenic mice that overexpress a dominant-negative variant of Nur77 in arterial SMCs, which provides evidence for the involvement of Nur77-like factors. CONCLUSIONS: Enhancement of the activity of Nur77 by 6-MP protects against excessive SMC proliferation and SMC-rich neointima formation. We propose that activation of the nuclear receptor Nur77 is a rational approach to treating in-stent restenosis.

The effect of interleukin-10 knock-out and overexpression on neointima formation in hypercholesterolemic APOE*3-Leiden mice.

OBJECTIVE: Inflammatory factors are thought to play a regulatory role in restenosis. Interleukin-10 (IL10) is an important anti-inflammatory cytokine with anti-atherogenic potentials. The aim of this study was to assess the effects of IL10 modulation on cuff-induced neointima formation in hypercholesterolemic APOE*3-Leiden mice. METHODS: The involvement of IL10 in neointima formation was studied in a hypercholesterolemic mouse model of cuff-induced stenosis of the femoral artery by IL10 knocking-out or overexpression procedures. IL10(+/-) mice were crossbred with APOE*3-Leiden mice to generate hypercholesterolemic APOE*3-LeidenIL10(-/-) mice. To achieve IL10 overexpression in APOE*3-Leiden mice, a single intramuscular injection of a murine IL10 overexpression plasmid was performed followed by electroporation. RESULTS: Knocking-out IL10, in hypercholesterolemic APOE*3-Leiden mice, resulted in a significant 1.9-fold increase of neointima surface as compared to APOE*3-LeidenIL10(+/+) littermates (p=0.02). Conversely, a marked 45% inhibition on cuff-induced neointima formation was obtained after IL10 overexpression (p=0.02). Electrodelivery of IL10 vector leads to detectable IL10 serum levels, with a sustained expression over the experimental period of 3 weeks. IL10 overexpression reduced plasma cholesterol levels in APOE*3-Leiden mice, whereas IL10 deficiency in these mice did not lead to altered cholesterol levels as compared to the IL10(+/+) group. Finally, IL10 overexpression stimulated endogenous IL10 mRNA expression in the spleen and reduced the transcriptional responses of several pro-inflammatory cytokines. CONCLUSION: Here, we clearly demonstrate the role of IL10 in the development of neointima formation in hypercholesterolemic mice and the potential therapeutic effect of non-viral electrodelivery of IL10 cDNA to inhibit post-angioplasty restenosis.

Inhibition of neointima formation by local delivery of estrogen receptor alpha and beta specific agonists.

OBJECTIVE: Neointima formation is the underlying mechanism of (in-stent) restenosis. 17beta-Estradiol (E2) is known to inhibit injury-induced neointima formation and post-angioplasty restenosis. Estrogen receptor alpha (ERalpha) has been demonstrated to mediate E2 anti-restenotic properties. However, the role of estrogen receptor beta (ERbeta) is not fully elucidated. In the present study, the specific role of vascular ERalpha and ERbeta in neointima formation is assessed. METHODS AND RESULTS: Neointima formation was induced by placement of a perivascular cuff around the femoral artery of male C57BL/6J mice. E2-eluting cuffs significantly inhibited cuff-induced neointima formation. To address the specific roles of ERalpha and ERbeta on neointima formation, the ERalpha-selective agonist 4,4',4''-(4-propyl-[1H]-pyrazole-1,3,5-triyl)tris-phenol (PPT) and the ERbeta-selective agonist 2,3-bis(4-hydroxy-phenyl)-propionitrile (DPN) were applied via a drug-eluting cuff. PPT inhibited neointima formation at low but not at high concentrations. Conversely, DPN inhibited neointima formation dose dependently. To demonstrate the specificity of these responses, an ERalpha-selective antagonist, MPP, was also used in combination with E2, PPT, or DPN. While the effect of PPT on neointima formation inhibition was blocked by co-delivery of MPP, E2 and DPN could still inhibit neointima formation. CONCLUSIONS: Our data suggest that, in addition to ERalpha, specific ERbeta activation inhibits neointima formation in a mouse model of restenosis. These data reveal a yet unidentified protective role of ERbeta on neointima formation.

Short-term dexamethasone treatment inhibits vein graft thickening in hypercholesterolemic ApoE3Leiden transgenic mice.

OBJECTIVE: The aim of this study was to assess whether the anti-inflammatory agent dexamethasone can inhibit vein graft thickening without the occurrence of serious side effects. METHODS: Venous interposition grafting was performed in the common carotid artery of hypercholesterolemic ApoE3Leiden transgenic mice. Mice were treated with dexamethasone (0.15 mg.kg(-1).d(-1) orally), and after 28 days, vein graft thickening was quantified. RESULTS: Treatment with dexamethasone resulted in a significant 43% reduction in lesion area without changes in lesion composition when compared with nontreated controls. However, dexamethasone, when administered for a prolonged period of time, is known for its potentially serious side effects. To overcome these potential side effects of prolonged dexamethasone treatment, the effect of a short-term 7-day dexamethasone treatment was studied. This short dexamethasone treatment resulted in a 49% decrease of vein graft thickening at 28 days. Furthermore, it was demonstrated that dexamethasone treatment led to reduced local expression of several proinflammatory cytokines and factors in the vein grafts 24 hours after surgery. Finally, observations in mice were verified in human saphenous organ cultures. Exposure to dexamethasone for either 7 or 28 days significantly reduced intimal hyperplasia formation on cultured saphenous vein segments. CONCLUSIONS: Short-term anti-inflammatory treatment with dexamethasone leads to a significant reduction in vein graft thickening over an extended period, possibly by the reduction of early expression of proinflammatory cytokines. This 7-day treatment minimizes the risk of unwanted side effects of long-term dexamethasone treatment and may be a new approach to prevent graft failure.

Drug-eluting stents studies in mice: do we need atherosclerosis to study restenosis?

In 2001, the first human study with drug-eluting stents (DES) was published showing a nearly complete abolition of restenosis by using a sirolimus-eluting stent. This success was very encouraging to test new compounds in combination with the DES platform. Nevertheless, several other anti-restenotic compounds have been used in human clinical trials with disappointing outcomes. Little is known concerning potential adverse effects on vessel wall integrity and (re)healing, atherosclerotic lesion formation, progression, and plaque stability of these DES. Although efficacy and safety need to be determined clinically, preclinical testing of candidate drugs in well-defined animal models is extremely helpful to gain insight into the basic biological responses to candidate compounds. Here, we discuss and report an animal model which enables rapid screening of candidate drugs for DES on an atherosclerotic background. The results from drug testing using this novel model could help to quickly and cost-effectively establish the dose range of candidate drugs with reasonable potential for DES.