Fast detection of bacterial gut pathogens on miniaturized devices: an overview

INTRODUCTION

Gut microbes pose challenges like colon inflammation, deadly diarrhea, antimicrobial resistance dissemination, and chronic disease onset. Development of early, rapid and specific diagnosis tools is essential for improving infection control. Point-of-care testing (POCT) systems offer rapid, sensitive, low-cost and sample-to-answer methods for microbe detection from various clinical and environmental samples, bringing the advantages of portability, automation, and simple operation.

AREAS COVERED

Rapid detection of gut microbes can be done using a wide array of techniques including biosensors, immunological assays, electrochemical impedance spectroscopy, mass spectrometry and molecular biology. Inclusion of Internet of Things, machine learning, and smartphone-based point-of-care applications is an important aspect of POCT. In this review, the authors discuss various fast diagnostic platforms for gut pathogens and their main challenges.

EXPERT OPINION

Developing effective assays for microbe detection can be complex. Assay design must consider factors like target selection, real-time and multiplex detection, sample type, reagent stability and storage, primer/probe design, and optimizing reaction conditions for accuracy and sensitivity. Mitigating these challenges requires interdisciplinary collaboration among scientists, clinicians, engineers, and industry partners. Future efforts are essential to enhance sensitivity, specificity, and versatility of POCT systems for gut microbe detection and quantification, advancing infectious disease diagnostics and management.

Liquid Biopsy: A Game Changer for Type 2 Diabetes

As the burden of type 2 diabetes (T2D) continues to escalate globally, there is a growing need for novel, less-invasive biomarkers capable of early diabetes detection and monitoring of disease progression. Liquid biopsy, recognized for its minimally invasive nature, is increasingly being applied beyond oncology, and nevertheless shows its potential when the collection of the tissue biopsy is not possible. This diagnostic approach involves utilizing liquid biopsy markers such as cell-free nucleic acids, extracellular vesicles, and diverse metabolites for the molecular diagnosis of T2D and its related complications. In this context, we thoroughly examine recent developments in T2D liquid biopsy research. Additionally, we discuss the primary challenges and future prospects of employing liquid biopsy in the management of T2D. Prognosis, diagnosis and monitoring of T2D through liquid biopsy could be a game-changing technique for personalized diabetes management.

Trends in Photothermal Nanostructures for Antimicrobial Applications

The rapid development of antimicrobial resistance due to broad antibiotic utilisation in the healthcare and food industries and the non-availability of novel antibiotics represents one of the most critical public health issues worldwide. Current advances in nanotechnology allow new materials to address drug-resistant bacterial infections in specific, focused, and biologically safe ways. The unique physicochemical properties, biocompatibility, and wide range of adaptability of nanomaterials that exhibit photothermal capability can be employed to develop the next generation of photothermally induced controllable hyperthermia as antibacterial nanoplatforms. Here, we review the current state of the art in different functional classes of photothermal antibacterial nanomaterials and strategies to optimise antimicrobial efficiency. The recent achievements and trends in developing photothermally active nanostructures, including plasmonic metals, semiconductors, and carbon-based and organic photothermal polymers, and antibacterial mechanisms of action, including anti-multidrug-resistant bacteria and biofilm removal, will be discussed. Insights into the mechanisms of the photothermal effect and various factors influencing photothermal antimicrobial performance, emphasising the structure-performance relationship, are discussed. We will examine the photothermal agents' functionalisation for specific bacteria, the effects of the near-infrared light irradiation spectrum, and active photothermal materials for multimodal synergistic-based therapies to minimise side effects and maintain low costs. The most relevant applications are presented, such as antibiofilm formation, biofilm penetration or ablation, and nanomaterial-based infected wound therapy. Practical antibacterial applications employing photothermal antimicrobial agents, alone or in synergistic combination with other nanomaterials, are considered. Existing challenges and limitations in photothermal antimicrobial therapy and future perspectives are presented from the structural, functional, safety, and clinical potential points of view.

Synthesis of ZnO/Au Nanocomposite for Antibacterial Applications

Annually, antimicrobial-resistant infections-related mortality worldwide accelerates due to the increased use of antibiotics during the coronavirus pandemic and the antimicrobial resistance, which grows exponentially, and disproportionately to the current rate of development of new antibiotics. Nanoparticles can be an alternative to the current therapeutic approach against multi-drug resistance microorganisms caused infections. The motivation behind this work was to find a superior antibacterial nanomaterial, which can be efficient, biocompatible, and stable in time. This study evaluated the antibacterial activity of ZnO-based nanomaterials with different morphologies, synthesized through the solvothermal method and further modified with Au nanoparticles through wet chemical reduction. The structure, crystallinity, and morphology of ZnO and ZnO/Au nanomaterials have been investigated with XRD, SEM, TEM, DLS, and FTIR spectroscopy. The antibacterial effect of unmodified ZnO and ZnO/Au nanomaterials against Escherichia coli and Staphylococcus aureus was investigated through disc diffusion and tetrazolium/formazan (TTC) assays. The results showed that the proposed nanomaterials exhibited significant antibacterial effects on the Gram-positive and Gram-negative bacteria. Furthermore, ZnO nanorods with diameters smaller than 50 nm showed better antibacterial activity than ZnO nanorods with larger dimensions. The antibacterial efficiency against Escherichia coli and Staphylococcus aureus improved considerably by adding 0.2% (w/w) Au to ZnO nanorods. The results indicated the new materials' potential for antibacterial applications.

Advances in the Rapid Diagnostic of Viral Respiratory Tract Infections

Viral infections are a significant public health problem, primarily due to their high transmission rate, various pathological manifestations, ranging from mild to severe symptoms and subclinical onset. Laboratory diagnostic tests for infectious diseases, with a short enough turnaround time, are promising tools to improve patient care, antiviral therapeutic decisions, and infection prevention. Numerous microbiological molecular and serological diagnostic testing devices have been developed and authorised as benchtop systems, and only a few as rapid miniaturised, fully automated, portable digital platforms. Their successful implementation in virology relies on their performance and impact on patient management. This review describes the current progress and perspectives in developing micro- and nanotechnology-based solutions for rapidly detecting human viral respiratory infectious diseases. It provides a nonexhaustive overview of currently commercially available and under-study diagnostic testing methods and discusses the sampling and viral genetic trends as preanalytical components influencing the results. We describe the clinical performance of tests, focusing on alternatives such as microfluidics-, biosensors-, Internet-of-Things (IoT)-based devices for rapid and accurate viral loads and immunological responses detection. The conclusions highlight the potential impact of the newly developed devices on laboratory diagnostic and clinical outcomes.

Antiviral Immunity in SARS-CoV-2 Infection: From Protective to Deleterious Responses

After two previous episodes, in 2002 and 2012, when two highly pathogenic coronaviruses (SARS, MERS) with a zoonotic origin emerged in humans and caused fatal respiratory illness, we are today experiencing the COVID-19 pandemic produced by SARS-CoV-2. The main question of the year 2021 is if naturally- or artificially-acquired active immunity will be effective against the evolving SARS-CoV-2 variants. This review starts with the presentation of the two compartments of antiviral immunity-humoral and cellular, innate and adaptive-underlining how the involved cellular and molecular actors are intrinsically connected in the development of the immune response in SARS-CoV-2 infection. Then, the SARS-CoV-2 immunopathology, as well as the derived diagnosis and therapeutic approaches, will be discussed.

Point-of-Care Testing-The Key in the Battle against SARS-CoV-2 Pandemic

The deleterious effects of the coronavirus disease 2019 (COVID-19) pandemic urged the development of diagnostic tools to manage the spread of disease. Currently, the "gold standard" involves the use of quantitative real-time polymerase chain reaction (qRT-PCR) for SARS-CoV-2 detection. Even though it is sensitive, specific and applicable for large batches of samples, qRT-PCR is labour-intensive, time-consuming, requires trained personnel and is not available in remote settings. This review summarizes and compares the available strategies for COVID-19: serological testing, Point-of-Care Testing, nanotechnology-based approaches and biosensors. Last but not least, we address the advantages and limitations of these methods as well as perspectives in COVID-19 diagnostics. The effort is constantly focused on understanding the quickly changing landscape of available diagnostic testing of COVID-19 at the clinical levels and introducing reliable and rapid screening point of care testing. The last approach is key to aid the clinical decision-making process for infection control, enhancing an appropriate treatment strategy and prompt isolation of asymptomatic/mild cases. As a viable alternative, Point-of-Care Testing (POCT) is typically low-cost and user-friendly, hence harbouring tremendous potential for rapid COVID-19 diagnosis.

Trends in hospitalized patients with cancer and stress cardiomyopathy

Introduction

Although cardiovascular disease (CVD) and cancer remain the top two causes of death worldwide, novel therapeutics have resulted in a decreased mortality rate in both groups. Accordingly, there has been a heightened awareness of patients with cancer experiencing stress cardiomyopathy (SC). In patients with cancer, the emotional stress of the diagnosis of cancer is compounded by the physical stress of treatments such as surgery, chemotherapy, immunotherapy, and radiotherapy. Previous studies have shown that SC in patients with cancer is associated with higher odds of in-hospital mortality when compared to patients with SC alone. No studies have examined the differences between patients with active cancer and SC compared to patients with active cancer without SC.

Purpose

To explore the unique impact that a diagnosis of SC has on patients with specific types of cancer, so that clinicians may recognize these phenomena and reduce morbidity associated with this disease.

Methods

We queried the 2016 United States National Inpatient Sample, which is the largest publicly available all-payer inpatient healthcare database, to identify demographic characteristics and outcomes in patients with active cancer and SC.

Results

Of 30,195,722 adult hospitalized patients, 4,719,591 (15.63%) had active cancer of whom 568,239 (12.04%) had SC. Among patients with active cancer, patients with SC versus those without SC were significantly more likely to have the following characteristics: female sex, white race, commercial insurance, hypertension, anemia, thrombocytopenia, and coagulation disorder (p<0.003 for all variables). The five most common primary malignancies in patients with SC were breast (13.4%), lung (10.2%), skin (9.5%), colon (8.1%), and leukemia (4.8%) (Figure 1).

In machine learning-augmented propensity score-adjusted multivariable regression fully adjusting for age, race, income, and presence of metastases, the only primary malignancies that significantly increased the likelihood of SC were lung cancer (OR 1.25; p=0.003) and breast cancer (OR 1.81; p<0.001) (Table 1). In separate regression, neither SC alone nor having both SC and cancer was significantly associated with mortality. The presence of concomitant SC and breast cancer was significantly associated with reduced mortality (OR 0.48; p=0.032).

Conclusion

In patients with active cancer, SC was not associated with in-hospital mortality. In addition, patients with both SC and breast cancer had significantly reduced mortality when compared to all patients with cancer. Further investigation will be necessary to confirm these findings and determine the possible protective factors in patients with SC and breast cancer. Furthermore, clinicians should be aware, early during hospitalization, of the increased likelihood of SC in patients with lung cancer and breast cancer, in order to reduce morbidity associated with these diagnoses.

Funding Acknowledgement

Type of funding sources: None.

E-Skin: The Dawn of a New Era of On-Body Monitoring Systems

Real-time "on-body" monitoring of human physiological signals through wearable systems developed on flexible substrates (e-skin) is the next target in human health control and prevention, while an alternative to bulky diagnostic devices routinely used in clinics. The present work summarizes the recent trends in the development of e-skin systems. Firstly, we revised the material development for e-skin systems. Secondly, aspects related to fabrication techniques were presented. Next, the main applications of e-skin systems in monitoring, such as temperature, pulse, and other bio-electric signals related to health status, were analyzed. Finally, aspects regarding the power supply and signal processing were discussed. The special features of e-skin as identified contribute clearly to the developing potential as in situ diagnostic tool for further implementation in clinical practice at patient personal levels.

Behavior problems associated with brain heterotopia

Introduction

Brain heterotopia represent a group of rare malformations with a heterogeneous phenotype, ranging from asymptomatic to severe clinical picture (resistant epilepsy, severe developmental delay). The etiology is multifactorial, including both genetic and environmental factors.

Objectives

In this paper we present our experience regarding behavior problems in patients with heterotopia.

Methods

A cohort of 16 pediatric patients with brain heterotopia, six females and ten males, with age at last follow-up ranging from 2 months to 24 years were investigated by clinical examination, electroencephalographic studies, brain imaging, and genomic tests. Specific psychological tests and psychiatric evaluation were performed in all children for behavior problems assessment.

Results

Six individuals presented behavioral problems: autism (three patients) and hyperkinesia with attention deficit (three patients). All of them had intellectual disability or learning problems; five patients had epilepsy, with drug-resistant seizures in four cases. In two cases the behavioral problems occurred before the onset of epileptic seizures.

Conclusions

Behavior problems are important features in patients with brain heterotopia, making the management of these patients more difficult, especially when they occur in association with drug-resistant epilepsy. Acknowledgements: This work was supported partially by grants of the Romanian National Authority for Scientific Research and Innovation CCCDI – UEFISCDI, Projects COFUND-ERANET E-RARE 3-HETER-OMICS-2 Number 87/2019 and 88/2019 within PNCDI III.

Disclosure

No significant relationships.

Multidisciplinary approach in children with autism spectrum disorder

Introduction

Autism spectrum disorder (ASD) is characterized by persistent deficits in social communication and social interaction across multiple contexts and it is marked by repetitive sensory–motor behaviours and restricted interests or activities. Now recognized to occur in up to 1% of the population, the prevalence of ASD has registered a steady increase in the past two decades. Heterogeneity of presentation is a hallmark with comorbid psychiatric and medical morbidities frequently reported. Comorbidities mask and delay the diagnosis and are the cause of inadequate therapies.

Objectives

In the present paper, we studied a cohort of patients with ASD, investigating the rates and types of psychiatric and medical comorbidities.

Methods

A retrospective study of psychiatric and medical comorbidities was carried out on a sample of 120 participants that met ASD criteria according to DSM-V. The patients were examined with a detailed medical history, physical examination, as well as some additional functional, imaging, laboratory and genetic investigations. The associated conditions considered were: attention deficit/hyperactivity disorder (ADHD), epilepsy, intellectual disability, gastrointestinal symptoms, ophtalmologic manifestations, infections.

Results

Of the 120 ASD subjects referred, 25 (20.8%) received the diagnosis of epilepsy. ADHD was established in 24 cases (20%). IQ score was obtained in half of the patients, 43.3% of them presenting a severe intellectual disability (IQ<35). Respiratory disorders occured in 25% of the cases. Ophtalmological findings were observed in 9.1% of the cases. Other frequent comorbidities included motor disturbances and feeding problems.

Conclusions

A better understanding of comorbidities in ASD patients improves interdisciplinary collaboration, thus facilitating effective treatment programs.

Disclosure

No significant relationships.

The psychiatric phenotype of 15q11.2-q13.3 duplications

Introduction

15q11.2-q13.3 region is prone to genomic rearrangements leading to both deletions and duplications. A wide spectrum of neuropsychiatric conditions, such as developmental delay/intellectual disability (DD/ID), autism, attention-deficit hyperactivity disorder, schizophrenia, epilepsy was reported in association with genomic imbalances of this region.

Objectives

In this paper we report on 9 children carrying 15q11.2-q13.3 duplications.

Methods

Seven boys and two girls, aged 15 months to 15 years, were included in the study. Genomic investigations were carried out by array-based comparative genomic hybridization (Agilent Technologies). In all patients the psychomotor development, dysmorphic features, neuroimaging and EEG anomalies were assessed. Psychologic and psychiatric evaluation was performed with specific tests.

Results

The size of the duplications ranged from 9.65 Mb to 0.38 Mb. All patients presented speech delay. Autistic behavior and muscular hypotonia were detected in 8 out of 9 patients, DD/ID in 6. Two children presented epileptic seizures, in addition 4 other children had EEG anomalies. Facial dysmorphic features were observed in 5 patients. Neuroimaging studies showed anomalies in 4 children. The smallest region of overlap in our patient group harbors CHRNA7 gene, a candidate for the behavioral abnormalities.

Conclusions

15q duplications encompassing CHRNA7 gene were associated with different neuropsychiatric features in our patients. Our results further support the association of 15q duplications with neuropsychiatric phenotypes, with clinical heterogeneity and variable severity, which is yet to be explained. Acknowledgment: The research leading to these results has received funding from the EEA RO NO Grant 2014-2021, the project contract No 6/2019.

Disclosure

No significant relationships.

Ultrashort Peptide Theranostic Nanoparticles by Microfluidic-Assisted Rapid Solvent Exchange

Ultrashort peptides (USPs), composed of three to seven amino acids, can self-assemble into nanofibers in pure water. Here, using hydrodynamic focusing and a solvent exchange method on a microfluidic setup, we convert these nanofibers into globular nanoparticles with excellent dimensional control and polydispersity. Thanks to USP nanocarriers' structure, different drugs can be loaded. We used Curcumin as a model drug to evaluate the performance of USP nanocarriers as a novel drug delivery vehicle. These nanoparticles can efficiently cross the cell membrane and possess nonlinear optical properties. Therefore, we envisage USP nanoparticles as promising future theranostic nanocarriers.

A vascular-liver chip for sensitive detection of nutraceutical metabolites from human pluripotent stem cell derivatives

Human pluripotent stem cell (hPSC) is a great resource for generating cell derivatives for drug efficiency testing. Metabolites of nutraceuticals can exert anti-inflammatory effects on blood vessels. However, the concentration of nutraceutical metabolites produced in hPSC-derived hepatocytes (hPSC-HEPs) is usually low. To enable the detection of these metabolites under the in vitro environment, we have developed a co-culture model consisting of parallel co-culture chambers and a recirculating microfluidic system with minimum fluid volume, optimal cell culture environment. The model allows cells to be exposed continuously to nutraceutical metabolites. In this perfused culturing model, hPSC-derived endothelial cells and hPSC-HEPs are co-cultured without physical contact. When an anti-inflammatory nutraceutical, quercetin, was administrated to the co-culture, higher levels of quercetin metabolites were detected on-chip compared with static control. We further induced inflammation with Interleukin-1β in the co-culture model and measured interleukin 8 (IL-8) generation. The IL-8 level was suppressed more significantly by quercetin metabolites in the perfusion co-culture, as compared to static culture. This is due to enhanced metabolites production on-chip. This microfluidic co-culture model enables in vitro screening of nutraceuticals using hPSC-derived cells.

IoT PCR for pandemic disease detection and its spread monitoring

During infectious disease outbreaks, the centers for disease control need to monitor particular areas. Considerable effort has been invested in the development of portable, user-friendly, and cost-effective systems for point-of-care (POC) diagnostics, which could also create an Internet of Things (IoT) for healthcare via a global network. However, at present IoT based on a functional POC instrument is not available. Here we show a fast, user-friendly, and affordable IoT system based on a miniaturized polymerase chain reaction device. We demonstrated the system's capability by amplification of complementary deoxyribonucleic acid (cDNA) of the dengue fever virus. The resulting data were then automatically uploaded via a Bluetooth interface to an Android-based smartphone and then wirelessly sent to a global network, instantly making the test results available anywhere in the world. The IoT system presented here could become an essential tool for healthcare centers to tackle infectious disease outbreaks identified either by DNA or ribonucleic acid.

Self-assembling amyloid-like peptides as exogenous second harmonic probes for bioimaging applications

Amyloid-like peptides are an ideal model for the mechanistic study of amyloidosis, which may lead to many human diseases, such as Alzheimer disease. This study reports a strong second harmonic generation (SHG) effect of amyloid-like peptides, having a signal equivalent to or even higher than those of endogenous collagen fibers. Several amyloid-like peptides (both synthetic and natural) were examined under SHG microscopy and shown they are SHG-active. These peptides can also be observed inside cells (in vitro). This interesting property can make these amyloid-like peptides second harmonic probes for bioimaging applications. Furthermore, SHG microscopy can provide a simple and label-free approach to detect amyloidosis. Lattice corneal dystrophy was chosen as a model disease of amyloidosis. Morphological difference between normal and diseased human corneal biopsy samples can be easily recognized, proving that SHG can be a useful tool for disease diagnosis.

P678Pericardiocentesis in thrombocytopenic cancer patients

Background

Pericardial effusion is a known complication in cancer patients, resulting in chest pain, cardiac tamponade, and cardiogenic shock. Although technological advances allow for early detection, treatment options are limited for those also suffering from thrombocytopenia.

Purpose

Our study aims to evaluate survivorship of thrombocytopenic cancer patients who underwent pericardiocentesis.

Methods

From 2008 to 2019, we assessed overall mortality and follow-up post-pericardiocentesis in cancer patients with concurrent thrombocytopenia (<150,000 cells/microliter) at our cancer center. Thrombocytopenia grading was determined on the procedure day via serology platelet cell count with the following thresholds: Grade 1 (<50x103 cells/mL), Grade 2 (51–100x103 cells/mL), and Grade 3 (101–149x103 cells/mL).

Results

In 137 patients, we identified 65 (47%) patients with Grade 1, 30 (22%) with Grade 2, and 42 (31%) with Grade 3 thrombocytopenia. The calculated platelet count average was 66x103 cells/mL, median was 59x103 cells/mL, and range was 6 to 147x103 cells/mL. Of note, 7 (5%) patients had platelets <10x103 cells/mL. One patient developed a hematoma at the percutaneous site of pericardial drain, no other complications were noted. Kaplan Meier survival analysis by log-rank (mantel-cox) showed statistical significance (p=0.025). Comparatively, the cumulative survival of patients at 30 days was 63% in Grade 1, 67% in Grade 2, and 83% in Grade 3 patients. At one year, it was 26% in Grade 1, 37% in Grade 2, and 48% in Grade 3 patients.

Conclusion

Pericardiocentesis offers rapid symptomatic relief and can be life-saving in cardiac tamponade. In cancer patients, the development of pericardial effusions and thrombocytopenia increases due to the underlying malignancy and cancer therapeutics. Although thrombocytopenia is thought to increase peri-procedural risks, in this cohort there was only one minor complication and this occurred in Grade 2 thrombocytopenia. For thrombocytopenic cancer patients suffering from large pericardial effusions, high pre-operative risk scores often exclude them from receiving surgical pericardial windows. Although mortality was higher in severe thrombocytopenia, this is likely due to the competing risk of more severe cancer; there were no complications with Grade 1 thrombocytopenia. Especially noteworthy, no complications in those with platelets <10,000 cells/uL. Our study shows that in this population of patients, pericardiocentesis is a feasible intervention with low complication rate to help improve quality of life and potentially life-saving treatment.

P3629Invasive versus medical management of non-ST elevation myocardial infarction in cancer patients: knowledge is bliss

Background

Cancer patients with non-ST elevation myocardial infarction (NSTEMI) frequently present with comorbidities (e.g., anaemia, thrombocytopenia) that discourage invasive treatment.

Purpose

To compare outcomes of cancer patients with NSTEMI treated with optimal medical therapy (OMT) + percutaneous coronary intervention (PCI) versus OMT alone and to identify variables associated with overall survival (OS).

Methods

All cancer patients diagnosed with NSTEMI between March 2016 and December 2018 at our institution were included. Patients were classified based on treatment of NSTEMI into 2 groups: invasive strategy or OMT alone. The invasive group was further classified into early (PCI≤72 hours since presentation) or delayed strategy (PCI>72 hours). Clinical and laboratory data, oncologic history, major adverse cardiovascular events, and survival were collected. Univariate Cox proportional hazards regression analyses were conducted to identify variables associated with OS.

Results

We included 201 patients with a mean age of 68±11 years, 136 (68%) of which were women. Median OS was 13 months. Factors influencing OS are presented in Table I. Patients receiving PCI had better OS compared to patients treated with OMT only (Figure 1, p<0.0001). Procedure-related complications were non-fatal and present in 2 (1.85%) cases.

Table I Covariate Hazard Ratio (95% confidence interval) p-value Early invasive treatment (≤72 hours) 0.327 (0.207–0.516) <0.0001 Delayed invasive treatment (>72 hours) 0.496 (0.252–0.977) 0.0426 Presenting symptom: chest pain 0.406 (0.254–0.649) 0.0002 Presenting symptom: others 1.869 (1.223–2.855) 0.0039 Single agent antiplatelet therapy 0.434 (0.263–0.716) 0.0011 Dual agent antiplatelet therapy 0.294 (0.174–0.496) <0.0001 Statins 0.440 (0.276–0.703) 0.0006 Active cancer 4.487 (1.646–12.234) 0.0033 Prior chemotherapy 2.312 (1.328–4.023) 0.0030 Prior chest radiation 1.752 (1.065–2.884) 0.0272 Active chemotherapy 1.931 (1.271–2.934) 0.0021

Figure 1

Conclusions

An invasive management of NSTEMI in cancer patients, especially within 72 hours, appears to be associated with improved OS. Patients presenting with symptoms other than chest pain were less likely to undergo PCI and had worse outcomes. Active cancer, a history of chest radiation, and active or prior chemotherapy were also associated with decreased OS.

Acknowledgement/Funding

None

Recent advances in microfluidic methods in cancer liquid biopsy

Early cancer detection, its monitoring, and therapeutical prediction are highly valuable, though extremely challenging targets in oncology. Significant progress has been made recently, resulting in a group of devices and techniques that are now capable of successfully detecting, interpreting, and monitoring cancer biomarkers in body fluids. Precise information about malignancies can be obtained from liquid biopsies by isolating and analyzing circulating tumor cells (CTCs) or nucleic acids, tumor-derived vesicles or proteins, and metabolites. The current work provides a general overview of the latest on-chip technological developments for cancer liquid biopsy. Current challenges for their translation and their application in various clinical settings are discussed. Microfluidic solutions for each set of biomarkers are compared, and a global overview of the major trends and ongoing research challenges is given. A detailed analysis of the microfluidic isolation of CTCs with recent efforts that aimed at increasing purity and capture efficiency is provided as well. Although CTCs have been the focus of a vast microfluidic research effort as the key element for obtaining relevant information, important clinical insights can also be achieved from alternative biomarkers, such as classical protein biomarkers, exosomes, or circulating-free nucleic acids. Finally, while most work has been devoted to the analysis of blood-based biomarkers, we highlight the less explored potential of urine as an ideal source of molecular cancer biomarkers for point-of-care lab-on-chip devices.

Microfluidic Technology for Clinical Applications of Exosomes

Exosomes, a type of nanovesicle, are distinct cellular entities specifically capable of carrying various cargos between cells. It has been hypothesized that exosomes, as an enriched source of biomolecules, may serve as biomarkers for various diseases. This review introduces general aspects of exosomes, presents the challenges in exosome research, discusses the potential of exosomes as biomarkers, and describes the contribution of microfluidic technology to enable their isolation and analysis for diagnostic and disease monitoring. Additionally, clinical applications of exosomes for diagnostic purposes are also summarized.

LAMP-on-a-chip: Revising microfluidic platforms for loop-mediated DNA amplification

Nucleic acid amplification for the detection of infectious diseases, food pathogens, or assessment of genetic disorders require a laboratory setting with specialized equipment and technical expertise. Isothermal deoxyribonucleic acid amplification methods, such as loop-mediated isothermal amplification (LAMP), exhibit characteristics ideal for point-of-care (POC) applications, since their instrumentation is simpler in comparison with the standard method of polymerase chain reaction. Other key advantages of LAMP are robustness and the production of pyrophosphate in the presence of the target gene, enabling to detect the reaction products using the naked eye. Polymerase inhibitors, presented in clinical samples, do not affect the amplification process, making LAMP suitable for a simple sample-to-answer diagnostic systems with simplified sample preparation. In this review, we discuss the trends in miniaturized LAMP techniques, such as microfluidic, paper-based, and digital with their advantages and disadvantages, especially for POC applications alongside our opinion of the future development of miniaturized LAMP.

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Introduction of loop mediated isothermal amplification (LAMP) and its principle.

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Classical microfluidics-based LAMP for DNA/RNA detection.

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Paper-based LAMP.

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Microfluidic-based digital LAMP.

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Future of microfluidic LAMP development.

Highlighting the uniqueness in dielectrophoretic enrichment of circulating tumor cells

Circulating tumor cells (CTCs) play an essential role in the metastasis of tumors, and thus can serve as a valuable prognostic factor for malignant diseases. As a result, the ability to isolate and characterize CTCs is essential. This review underlines the potential of dielectrophoresis for CTCs enrichment. It begins by summarizing the key performance parameters and challenges of CTCs isolation using microfluidics. The two main categories of CTCs enrichment-affinity-based and label-free methods-are analysed, emphasising the advantages and disadvantages of each as well as their clinical potential. While the main argument in favour of affinity-based methods is the strong specificity of CTCs isolation, the major advantage of the label-free technologies is in preserving the integrity of the cellular membrane, an essential requirement for downstream characterization. Moving forward, we try to answer the main question: "What makes dielectrophoresis a method of choice in CTCs isolation?" The uniqueness of dielectrophoretic CTCs enrichment resides in coupling the specificity of the isolation process with the conservation of the membrane surface. The specificity of the dielectrophoretic method stems from the differences in the dielectric properties between CTCs and other cells in the blood: the capacitances of the malignantly transformed cellular membranes of CTCs differ from those of other cells. Examples of dielectrophoretic devices are described and their performance evaluated. Critical requirements for using dielectrophoresis to isolate CTCs are highlighted. Finally, we consider that DEP has the potential of becoming a cytometric method for large-scale sorting and characterization of cells.

Tumor-derived circulating endothelial cell clusters in colorectal cancer

Clusters of tumor cells are often observed in the blood of cancer patients. These structures have been described as malignant entities for more than 50 years, although their comprehensive characterization is lacking. Contrary to current consensus, we demonstrate that a discrete population of circulating cell clusters isolated from the blood of colorectal cancer patients are not cancerous but consist of tumor-derived endothelial cells. These clusters express both epithelial and mesenchymal markers, consistent with previous reports on circulating tumor cell (CTC) phenotyping. However, unlike CTCs, they do not mirror the genetic variations of matched tumors. Transcriptomic analysis of single clusters revealed that these structures exhibit an endothelial phenotype and can be traced back to the tumor endothelium. Further results show that tumor-derived endothelial clusters do not form by coagulation or by outgrowth of single circulating endothelial cells, supporting a direct release of clusters from the tumor vasculature. The isolation and enumeration of these benign clusters distinguished healthy volunteers from treatment-naïve as well as pathological early-stage (≤IIA) colorectal cancer patients with high accuracy, suggesting that tumor-derived circulating endothelial cell clusters could be used as a means of noninvasive screening for colorectal cancer. In contrast to CTCs, tumor-derived endothelial cell clusters may also provide important information about the underlying tumor vasculature at the time of diagnosis, during treatment, and throughout the course of the disease.

On chip two-photon metabolic imaging for drug toxicity testing

We have developed a microfluidic system suitable to be incorporated with a metabolic imaging method to monitor the drug response of cells cultured on a chip. The cells were perfusion-cultured to mimic the blood flow in vivo. Label-free optical measurements and imaging of nicotinamide adenine dinucleotide and flavin adenine dinucleotide fluorescence intensity and morphological changes were evaluated non-invasively. Drug responses calculated using redox ratio imaging were compared with the drug toxicity testing results obtained with a traditional well-plate system. We found that our method can accurately monitor the cell viability and drug response and that the IC50 value obtained from imaging analysis was sensitive and comparable with a commonly used cell viability assay: MTS (3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfo-phenyl)-2H-tetrazolium) assay. Our method could serve as a fast, non-invasive, and reliable way for drug screening and toxicity testing as well as enabling real-time monitoring of in vitro cultured cells.

Polymeric Microneedle Array Fabrication by Photolithography

This manuscript describes the fabrication of polymeric microneedle (MN) arrays by photolithography. It involves a simple mold-free process by using a photomask consisting of embedded micro-lenses. Embedded micro-lenses were found to influence MN geometry (sharpness). Robust MN arrays with tip diameters ranging between 41.5 µm ± 8.4 µm and 71.6 µm ± 13.7 µm, with two different lengths (1,336 µm ± 193 µm and 957 µm ± 171 µm) were fabricated. These MN arrays may provide potential applications in delivery of low molecular and macromolecular therapeutic agents through skin.

On-chip controlled surfactant-DNA coil-globule transition by rapid solvent exchange using hydrodynamic flow focusing

This paper presents a microfluidic method for precise control of the size and polydispersity of surfactant-DNA nanoparticles. A mixture of surfactant and DNA dispersed in 35% ethanol is focused between two streams of pure water in a microfluidic channel. As a result, a rapid change of solvent quality takes place in the central stream, and the surfactant-bound DNA molecules undergo a fast coil-globule transition. By adjusting the concentrations of DNA and surfactant, fine-tuning of the nanoparticle size, down to a hydrodynamic diameter of 70 nm with a polydispersity index below 0.2, can be achieved with a good reproducibility.

Fine control over the size of surfactant-polyelectrolyte nanoparticles by hydrodynamic flow focusing

Synthesis of surfactant-polyelectrolyte nanoparticles was carried out in a microfluidic device with a fine control over the size and the polydispersity. An anionic polysaccharide (sodium carboxymethylcellulose, CMC) solution was focused using a cationic surfactant (dodecyl trimethylammonium bromide, DTAB) solution in a microfluidic channel at selected ratios of flow rates and reagent concentrations. The methodology ensured a controlled mixing kinetics and a uniform distribution of charges at the mixing interface. The resulting nanoparticles exhibited remarkably well-defined and repeatable size distributions, with hydrodynamic diameters tunable from 50 up to 300 nm and polydispersity index around 0.1 in most cases. Microfluidic-assisted self-assembly may be an efficient way to produce well-controlled polyelectrolyte-based nanoparticles suitable for colloidal science as well as for gene delivery applications.

Label-free isolation of circulating tumor cells in microfluidic devices: Current research and perspectives

This review will cover the recent advances in label-free approaches to isolate and manipulate circulating tumor cells (CTCs). In essence, label-free approaches do not rely on antibodies or biological markers for labeling the cells of interest, but enrich them using the differential physical properties intrinsic to cancer and blood cells. We will discuss technologies that isolate cells based on their biomechanical and electrical properties. Label-free approaches to analyze CTCs have been recently invoked as a valid alternative to "marker-based" techniques, because classical epithelial and tumor markers are lost on some CTC populations and there is no comprehensive phenotypic definition for CTCs. We will highlight the advantages and drawbacks of these technologies and the status on their implementation in the clinics.

Lifestyle counseling in patients with carotid arteriosclerosis from Luxemburg should focus more on the reduction of sugar, sodium and saturated fat consumption

BACKGROUND

Healthy diet and physical activity improve risk factors for cerebrovascular disease. It is unclear whether patients with carotid artery disease from Luxemburg meet common guideline criteria and whether systematic counseling has a sustained effect.

METHODS

We assessed anthropometric data, eating habits and physical activity habits in 53 patients with carotid atherosclerosis at baseline, after 4 and 20 weeks, and advised them five times for 30 min to follow a modified Mediterranean diet and to perform moderate physical exercise at least during 30 min/day.

RESULTS

The patients had a mildly increased BMI (mean 27.6, recommended below 25), they already ate enough vegetables and fruits (mean 485 g daily, recommended at least 400 g), they ate too much sugar (mean 74 g daily) and sodium (mean 2710 mg daily, recommended less than 1500), they consumed 13% of calories from saturated fatty acids (recommended less than 10%), and they already moved sufficiently (62 min daily of moderate and intense physical activity, recommended at least 30 min of moderate physical activity). Lifestyle counseling had a sustained effect on weight, reduction of global caloric intake, carbohydrate and cholesterol intake and on an increase in consumption of poly-unsaturated fatty acids, vegetables and fibres. There was no sustained effect on the consumption of sugar, sodium, and saturated fat.

CONCLUSIONS

The reduction of sugar, sodium and saturated fat consumption should be stressed more in counselling of this patient group.

Fish and Chips: a microfluidic perfusion platform for monitoring zebrafish development

We have developed a multi-channel microfluidic perfusion platform for culturing zebrafish embryos and capturing live images of various tissues and organs inside the embryo. The Fish and Chips was micro-fabricated in silicon and glass for reproducibility and accuracy of the microfluidic structure. The microfluidic platform consists of three parts: a microfluidic gradient generator, a row of eight fish tanks, in which the fish embryos are individually placed, and eight output channels. The fluidic gradient generator supports dose-dependent drug and chemical studies. A unique perfusion system ensures a uniform and constant flow of media to the fish tank while the wastes are efficiently removed. The fish tanks restrict the embryo movements, except rotationally, for live imaging of internal tissues and organs. The embryos showed developmental abnormalities under the influence of the drug valproic acid (VPA).

A practical guide for the fabrication of microfluidic devices using glass and silicon

This paper describes the main protocols that are used for fabricating microfluidic devices from glass and silicon. Methods for micropatterning glass and silicon are surveyed, and their limitations are discussed. Bonding methods that can be used for joining these materials are summarized and key process parameters are indicated. The paper also outlines techniques for forming electrical connections between microfluidic devices and external circuits. A framework is proposed for the synthesis of a complete glass/silicon device fabrication flow.

Home telemonitoring (forced expiratory volume in 1 s) in children with severe asthma does not reduce exacerbations

Some children with severe asthma develop frequent exacerbations despite intensive treatment. We sought to assess the outcome (severe exacerbations and healthcare use, lung function, quality of life and maintenance treatment) of a strategy based on daily home spirometry with teletransmission to an expert medical centre and whether it differs from that of a conventional strategy. 50 children with severe uncontrolled asthma were enrolled in a 12-month prospective study and were randomised into two groups: 1) treatment managed with daily home spirometry and medical feedback (HM) and 2) conventional treatment (CT). The children's mean age was 10.9 yrs (95% confidence interval 10.2-11.6). 44 children completed the study (21 in the HM group and 23 in the CT group). The median number of severe exacerbations per patient was 2.0 (interquartile range 1.0-4.0) in the HM group and 3.0 (1.0-4.0) in the CT group (p=0.38 with adjustment for age). There were no significant differences between the two groups for unscheduled visits (HM 5.0 (3.0-7.0), CT 3.0 (2.0-7.0); p=0.30), lung function (pre-β(2)-agonist forced expiratory volume in 1 s (FEV(1)) p=0.13), Paediatric Asthma Quality of Life Questionnaire scores (p=0.61) and median daily dose of inhaled corticosteroids (p=0.86). A treatment strategy based on daily FEV(1) monitoring with medical feedback did not reduce severe asthma exacerbations.

Exploitation of physical and chemical constraints for three-dimensional microtissue construction in microfluidics

There are a plethora of approaches to construct microtissues as building blocks for the repair and regeneration of larger and complex tissues. Here we focus on various physical and chemical trapping methods for engineering three-dimensional microtissue constructs in microfluidic systems that recapitulate the in vivo tissue microstructures and functions. Advances in these in vitro tissue models have enabled various applications, including drug screening, disease or injury models, and cell-based biosensors. The future would see strides toward the mesoscale control of even finer tissue microstructures and the scaling of various designs for high throughput applications. These tools and knowledge will establish the foundation for precision engineering of complex tissues of the internal organs for biomedical applications.

Dielectrophoretic field-flow method for separating particle populations in a chip with asymmetric electrodes

This paper presents a field-flow method for separating particle populations in a dielectrophoretic (DEP) chip with asymmetric electrodes under continuous flow. The structure of the DEP device (with one thick electrode that defines the walls of the microfluidic channel and one thin electrode), as well as the fabrication and characterization of the device, was previously described. A characteristic of this structure is that it generates an increased gradient of electric field in the vertical plane that can levitate the particles experiencing negative DEP. The separation method consists of trapping one population to the bottom of the microfluidic channel using positive DEP, while the other population that exhibits negative DEP is levitated and flowed out. Viable and nonviable yeast cells were used for testing of the separation method.

A 3-D dielectrophoretic filter chip

The paper presents a 3-D filter chip employing both mechanical and dielectrophoretic (DEP) filtration, and its corresponding microfabrication techniques. The device structure is similar to a classical capacitor: two planar electrodes, made from a stainless steel mesh, and bonded on both sides of a glass frame filled with round silica beads. The solution with the suspension of particles flows through both the mesh-electrodes and silica beads filter. The top stainless steel mesh (with openings of 60 mum and wires of 30 mum-thickness) provides the first stage of filtration based on mechanical trapping. A second level of filtration is based on DEP by using the nonuniformities of the electric field generated in the capacitor due to the nonuniformities of the dielectric medium. The filter can work also with DC and AC electric fields. The device was tested with yeast cells (Saccharomyces cerevisae) and achieved a maximal trapping efficiency of 75% at an applied AC voltage of 200 V and a flow rate of 0.1 mL/min, from an initial concentration of cells of 5 x 10(5) cells/mL. When the applied frequency was varieted in the range between 20 and 200 kHz, a minimal value of capture efficiency (3%) was notticed at 50 kHz, when yeast cells exhibit negative DEP and the cells are repelled in the space between the beads.

[Difficult asthma in children]

Difficult asthma in children is defined as the persistence of exacerbations or frequent symptoms requiring rescue bronchodilator, or persistent airway obstruction in spite of treatment with inhaled steroid >/= 800 microg/d beclomethasone or equivalent and beta-2 long acting agonist. Management of difficult asthma in children first requires to identify conditions that may mimic asthma, asthma with bad compliance to treatment, and difficult asthma in relation with avoidable factors that worsen symptoms. The pathological bases of genuine difficult asthma remain unknown. Different patterns have been described according to the cells that are involved (eosinophil, neutrophil), the degree of airway remodeling, or the distal localization of the lesions. Difficult asthma requires specialized management including airway inflammation evaluation. Studies on bronchoalveolar lavage and bronchial mucosa biopsies will perhaps help to better understand the pathophysiology and to improve the management.

Does nephroblastomatosis influence the natural history and relapse rate in Wilms' tumour? A single centre experience over 11 years

The presence of multifocal or diffuse nephrogenic rests (NRs) in one or both kidneys is termed nephroblastomatosis (Nbm). Nbm may be a predisposing factor for Wilms' tumour (WT). The aim of this retrospective study was to evaluate the impact of Nbm on the outcome of WT in children. We assessed the outcome of 81 children with Wilms tumours and practical implications of Nbm in the treatment and follow-up. All the pathology slides have been reviewed in 1997. 63 had WT without Nbm (group A) and 18 had WT associated with Nbm (group B). There was no statistical difference between the two groups according to the age at diagnosis and histology. Clinical abnormalities were more frequent in group B (33 versus 8%). There was no statistical difference between the percentage of stage IV in both groups, but bilaterality (stage V) was present only in the group B. Relapse was observed in 20/81 patients (25%): 11 (17%) in group A and 9 (50%) in group B. Mean delay of relapse was longer (25 months) in group B than in group A (10 months). For the whole population, with a median follow-up of 9 years, the event-free survival (EFS) and the overall survival (OS) probabilities were respectively 74%+/-10 and 83%+/-9 at 120 months. The difference in EFS between groups A (82+/-9%) and B (38%+/-29) was significant (P=0.004). The discovery of Nbm in the non-tumoral part of the kidney with WT can be an adverse factor and in particular favours the subsequent development of a new Wilms tumour. It justifies separate follow-up guidelines.