Current and emerging trends in point-of-care urinalysis tests

Acoustofluidic-based microscopic examination for automated and point-of-care urinalysis

Urinalysis is a heavily used diagnostic test in clinical laboratories; however, it is chronically held back by urine sediment microscopic examination. Current instruments are bulky and expensive to be widely adopted, making microscopic examination a procedure that still relies on manual operations and requires large time and labor costs. To improve the efficacy and automation of urinalysis, this study develops an acoustofluidic-based microscopic examination system. The system utilizes the combination of acoustofluidic manipulation and a passive hydrodynamic mechanism, and thus achieves a high throughput (1000 μL min-1) and a high concentration factor (95.2 ± 2.1 fold) simultaneously, fulfilling the demands for urine examination. The concentrated urine sample is automatically dispensed into a hemocytometer chamber and the images are then analyzed using a machine learning algorithm. The whole process is completed within 3 minutes with detection accuracies of erythrocytes and leukocytes of 94.6 ± 3.5% and 95.1 ± 1.8%, respectively. The examination outcome of urine samples from 50 volunteers by this device shows a correlation coefficient of 0.96 compared to manual microscopic examination. Our system offers a promising tool for automated urine microscopic examination, thus it has potential to save a large amount of time and labor in clinical laboratories, as well as to promote point-of-care urine testing applications in and beyond hospitals.

Evaluation of the predictors and frequency of silent hypoxemia in COVID-19 patients and the gap between pulse oximeter and arterial blood gas levels: A cross-sectional study

Background

Silent hypoxemia is when patients do not experience breathing difficulty in the presence of alarmingly low O2 saturation. It could cause rapid deterioration and higher mortality rates among patients, so prompt detection and identifying predictive factors could result in significantly better outcomes. This study aims to document the evidence of silent hypoxemia in patients with COVID-19 and its clinical features.

Methods

A total of 78 hospitalized, nonintubated patients with confirmed COVID-19 infection were included in this study. Their O2 saturation was measured with a pulse oximeter (PO), and arterial blood gas (ABG) was taken. Demographic and clinical features were recorded. The Borg scale was used to evaluate dyspnea status, and patients with a score of less than two accompanied by O2 saturation of less than 94% were labeled as silent hypoxic. Univariate analysis was utilized to evaluate the correlation between variables and their odds ratio (OR) and 95% confidence interval (CI).

Results

Silent hypoxemia was observed in 20 (25.6%) of the participants. The average difference between the PO and ABG methods was 4.36 ± 3.43. Based on regression analysis, dyspnea and respiratory rate demonstrated a statistically significant correlation with the O2 saturation difference between PO and ABG (OR: 2.05; p = 0.026; 95% CI: 0.248-3.847 and OR: 0.144; p = 0.048, 95% CI: 0.001-0.286). Furthermore, the Borg scale (OR: 0.29; p = 0.009; 95% CI: 0.116-0.740) had a significant reverse correlation with silent hypoxia.

Conclusions

Silent hypoxemia can be a possible complication that affects some COVID-19 patients. Further care should be bestowed upon the younger population and those with underlying neurological or mental illnesses. Furthermore, the respiratory rate, pulse oximeter, and arterial blood gas O2 levels should be considered alongside each other.

Urine Test Strip Quantitative Assay with a Smartphone Camera

Urine test strips for urinalysis are a common diagnostic tool with minimal costs and are used in various situations including homecare and hospitalization. The coloration scaled by the naked eye is simple, but it is suitable for semiquantitative analysis only. In this paper, a colorimetric assay is developed based on a smartphone digital camera and urine test strips. Assays of pH, albumin, glucose, and lipase activity were performed as a tool for the diagnosis of aciduria, alkaluria, glycosuria, proteinuria, and leukocyturia. The RGB color channels were analyzed in the colorimetric assay, and the assay exerted good sensitivity, and all the particular diagnoses proved to be reliable. The limits of detection for glucose (0.11 mmol/L), albumin (0.15 g/L), and lipase (2.50 U/μL) were low enough to cover the expected physiological concentration, and the range for pH was also satisfactory. The urine test strips with a camera as an output detector proved applicability to spiked urine samples, and the results were also well in comparison to the standard assays which confirms the practical relevance of the presented findings.

Machine learning-assisted image label-free smartphone platform for rapid segmentation and robust multi-urinalysis

This study presents a groundbreaking approach for the early detection of chronic kidney disease (CKD) and other urological disorders through an image-label-free, multi-dipstick identification method, eliminating the need for complex machinery, label libraries, or preset coordinates. Our research successfully identified reaction pads on 187 multi-dipsticks, each with 11 pads, leveraging machine learning algorithms trained on human urine data. This technique aims to surpass traditional colourimetric methods and concentration-colour curve fitting, offering more robust and precise community screening and home monitoring capabilities. The developed algorithms enhance the generalizability of machine learning models by extracting primary colours and correcting urine colours on each reaction pad. This method's cost-effectiveness and portability are significant, as it requires no additional equipment beyond a standard smartphone. The system's performance rivals professional medical equipment without auxiliary lighting or flash under regular indoor light conditions, effectively managing false positives and negatives across various categories with remarkable accuracy. In a controlled experimental setting, we found that random forest algorithms, based on a Bagging strategy and applied in the HSV colour space, showed optimal results in smartphone-assisted urinalysis. This study also introduces a novel urine colour correction method, significantly improving machine learning model performance. Additionally, ISO parameters were identified as crucial factors influencing the accuracy of smartphone-based urinalysis in the absence of additional lighting or optical configurations, highlighting the potential of this technology in low-resource settings.

Microfluidic systems for infectious disease diagnostics

Microorganisms, encompassing both uni- and multicellular entities, exhibit remarkable diversity as omnipresent life forms in nature. They play a pivotal role by supplying essential components for sustaining biological processes across diverse ecosystems, including higher host organisms. The complex interactions within the human gut microbiota are crucial for metabolic functions, immune responses, and biochemical signalling, particularly through the gut-brain axis. Viruses also play important roles in biological processes, for example by increasing genetic diversity through horizontal gene transfer when replicating inside living cells. On the other hand, infection of the human body by microbiological agents may lead to severe physiological disorders and diseases. Infectious diseases pose a significant burden on global healthcare systems, characterized by substantial variations in the epidemiological landscape. Fast spreading antibiotic resistance or uncontrolled outbreaks of communicable diseases are major challenges at present. Furthermore, delivering field-proven point-of-care diagnostic tools to the most severely affected populations in low-resource settings is particularly important and challenging. New paradigms and technological approaches enabling rapid and informed disease management need to be implemented. In this respect, infectious disease diagnostics taking advantage of microfluidic systems combined with integrated biosensor-based pathogen detection offers a host of innovative and promising solutions. In this review, we aim to outline recent activities and progress in the development of microfluidic diagnostic tools. Our literature research mainly covers the last 5 years. We will follow a classification scheme based on the human body systems primarily involved at the clinical level or on specific pathogen transmission modes. Important diseases, such as tuberculosis and malaria, will be addressed more extensively.

AI-Enhanced Visual-Spectral Synergy for Fast and Ultrasensitive Biodetection of Breast Cancer-Related miRNAs

In biomedical testing, artificial intelligence (AI)-enhanced analysis has gradually been applied to the diagnosis of certain diseases. This research employs AI algorithms to refine the precision of integrative detection, encompassing both visual results and fluorescence spectra from lateral flow assays (LFAs), which signal the presence of cancer-linked miRNAs. Specifically, the color shift of gold nanoparticles (GNPs) is paired with the red fluorescence from nitrogen vacancy color centers (NV-centers) in fluorescent nanodiamonds (FNDs) and is integrated into LFA strips. While GNPs amplify the fluorescence of FNDs, in turn, FNDs enhance the color intensity of GNPs. This reciprocal intensification of fluorescence and color can be synergistically augmented with AI algorithms, thereby improving the detection sensitivity for early diagnosis. Supported by the detection platform based on this strategy, the fastest detection results with a limit of detection (LOD) at the fM level and the R2 value of ∼0.9916 for miRNA can be obtained within 5 min. Meanwhile, by labeling the capture probes for miRNA-21 and miRNA-96 (both of which are early indicators of breast cancer) on separate T-lines, simultaneous detection of them can be achieved. The miRNA detection methods employed in this study may potentially be applied in the future for the early detection of breast cancer.

Duplex Vertical-Flow Rapid Tests for Point-of-Care Detection of Anti-dsDNA and Anti-Nuclear Autoantibodies

The goal of this study is to develop a rapid diagnostic test for rheumatic disease and systemic lupus erythematosus (SLE) screening. A novel rapid vertical flow assay (VFA) was engineered and used to assay anti-nuclear (ANA) and anti-dsDNA (αDNA) autoantibodies from systemic lupus erythematosus (SLE) patients and healthy controls (HCs). Observer scores and absolute signal intensities from the VFA were validated via ELISA. The rapid point-of-care VFA test that was engineered demonstrated a limit of detection of 0.5 IU/mL for ANA and αDNA autoantibodies in human plasma with an inter-operator CV of 19% for ANA and 12% for αDNA. Storage stability was verified over a three-month period. When testing anti-dsDNA and ANA levels in SLE and HC serum samples, the duplex VFA revealed 95% sensitivity, 72% specificity and an 84% ROC AUC value in discriminating disease groups, comparable to the gold standard, ELISA. The rapid αDNA/ANA duplex VFA can potentially be used in primary care clinics for evaluating patients or at-risk subjects for rheumatic diseases and for planning follow-up testing. Given its low cost, ease, and rapid turnaround, it can also be used to assess SLE prevalence estimates.

Telemedicine for Kidney Transplant Recipients: Current State, Advantages, and Barriers

Telemedicine is defined as the use of electronic information and communication technologies to provide and support healthcare at a distance. In kidney transplantation, telemedicine is limited but is expected to grow markedly in the coming y. Current experience shows that it is possible to provide transplant care at a distance, with benefits for patients like reduced travel time and costs, better adherence to medication and appointment visits, more self-sufficiency, and more reliable blood pressure values. However, multiple barriers in different areas need to be overcome for successful implementation, such as recipients' preferences, willingness, skills, and digital literacy. Moreover, in many countries, limited digital infrastructure, legislation, local policy, costs, and reimbursement issues could be barriers to the implementation of telemedicine. Finally, telemedicine changes the way transplant professionals provide care, and this transition needs time, training, willingness, and acceptance. This review discusses the current state and benefits of telemedicine in kidney transplantation, with the aforementioned barriers, and provides an overview of future directions on telemedicine in kidney transplantation.

Linker optimization and activity validation of a cell surface vimentin targeted homo-dimeric peptoid antagonist for lung cancer stem cells

Epithelial-to-mesenchymal transition (EMT) endows epithelia-derived cancer cells with properties of stem cells that govern cancer invasion and metastasis. Vimentin is one of the best studied EMT markers and recent reports indicate that vimentin interestingly translocated onto cell surface under various tumor conditions. We recently reported a cell surface vimentin (CSV) specific peptoid antagonist named JM3A. We now investigated the selective antagonist activity of the optimized homo-dimeric version of JM3A, JM3A-L2D on stem-like cancer cells or cancer stem cells (CSCs) over normal cells in non-small cell lung cancer (NSCLC). Homo-dimerization of JM3A provided the avidity effect and improved the biological activity compared to the monomeric version. We first optimized the central linker length of the dimer by designing seven JM3A derivatives with varying linker lengths/types and evaluated the anti-cancer activity using the standard MTS cell viability assay. The most optimized derivative contains a central lysine linker and two glycines, named JM3A-L2D, which displayed 100 nM vimentin binding affinity (Kd) with an anti-cancer activity (IC50) of 6.7 µM on H1299 NSCLC cells. This is a 190-fold improvement in binding over the original JM3A. JM3A-L2D exhibited better potency on high vimentin-expressing NSCLC cells (H1299 and H460) compared to low vimentin-expressing NSCLC cells (H2122). No activity was observed on normal bronchial HBEC3-KT cells. The anti-CSC activity of JM3A-L2D was evaluated using the standard colony formation assay and JM3A-L2D disrupted the colony formation with IC50 ∼ 400 nM. In addition, JM3A-L2D inhibited cell migration activity at IC50 ∼ 2 µM, assessed via wound healing assay. The underlying mechanism of action seems to be the induction of apoptosis by JM3A-L2D on high-vimentin expressing H1229 and H460 NSCLC cells. Our optimized highly CSV selective peptoid has the potential to be developed as an anti-cancer drug candidate, especially considering the high serum stability and economical synthesis of peptoids.

Urine dipstick for screening plasma glucose and bilirubin in low resource settings: a proof-of-concept study

Objectives

The purpose of this proof-of-concept study was to investigate whether a commercially available urine dipstick may provide potentially useful information for screening plasma glucose and bilirubin in human plasma samples.

Methods

Glucose and bilirubin were assayed in 60 anonymized lithium-heparin residual plasma samples using the Roche COBAS 8000 or after pipetting 10 µL of plasma onto the pads of a commercial urine dipstick. Semiquantitative urine test results obtained with the dipstick were directly compared to paired test results obtained with COBAS.

Results

Median plasma glucose values between COBAS and dipstick were slightly different (5.8 vs. 5.6 mmol/L; p=0.040), while no significant difference was found in bilirubin values between COBAS and dipstick (11.2 vs. 8.6 μmol/L; p=0.090). The Spearman's correlation between COBAS and dipstick was 0.83 (95% CI, 0.73-0.90; p<0.001) for plasma glucose and 0.78 (95% CI, 0.66-0.87; p<0.001) for plasma bilirubin, respectively. Cumulative agreement between COBAS and dipstick was high for both glucose (88%; kappa statistic statistics, 0.75; 95% CI, 0.58-0.92; p<0.001) and bilirubin (88%; kappa statistics, 0.76; 95% CI, 0.60-0.92; p<0.001).

Conclusions

The results of this proof-of-concept study indicate that the commercial urine test strip used in our study provides acceptable performance for screening plasma glucose and bilirubin levels compared with reference laboratory assays.

Uso de una tira reactiva paraorina en la evaluación de las concentraciones de glucosa y bilirrubina en plasma en entornos con recursos limitados: un estudio de prueba de concepto

Objetivos

El objetivo del presente estudio de prueba de concepto, era investigar si una tira reactiva comercial para orina aporta información potencialmente útil para la evaluación de glucosa y bilirrubina en muestras de plasma humano.

Métodos

Se determinaron las concentraciones de glucosa y bilirrubina en 60 muestras anonimizadas de plasma residual de heparina de litio, en un analizador Roche COBAS 8000 y en la tira reactiva comercial para orina, tras pipetear 10 µL de plasma, en las almohadillas que ésta incorpora. Se llevó a cabo una comparación directa entre los resultados semicuantitativos de la tira reactiva y los de las muestras pareadas obtenidos con el analizador COBAS.

Resultados

Se observaron leves diferencias entre el analizador COBAS y la tira reactiva en relación a la mediana de la concentración de glucosa (5,8 frente a 5,6 mmol/L, respectivamente; p=0,040). Por otro lado, no se observaron diferencias estadísticamente significativas en los valores de bilirrubina entre COBAS y la tira reactiva (11,2 frente a 8,6 μmol/L; p=0,090). El coeficiente de correlación de Spearman entre COBAS y la tira reactiva fue de 0,83 (IC 95 %, 0,73–0,90; p<0,001) para la glucosa en plasma, y 0,78 (IC 95 %, 0,66–0,87; p<0,001) para la bilirrubina en plasma. La concordancia acumulada entre COBAS y la tira reactiva fue alta tanto para la glucosa (88 %; coeficiente kappa, 0.75; IC 95 %, 0,58–0,92; p<0,001) como para la bilirrubina (88 %; coeficiente kappa, 0,76; IC 95 %, 0,60–0.92; p<0,001).

Conclusiones

Los resultados del estudio de prueba de concepto indican que la tira reactiva comercial para orina de nuestro estudio posee un rendimiento aceptable en la determinación de las concentraciones de glucosa y bilirrubina en plasma, en comparación con las pruebas analíticas de referencia.

Comparison of "hock-a-loogie" saliva versus nasopharyngeal and oropharyngeal swabs for detecting common respiratory pathogens

Self-collection of saliva samples has attracted considerable attention in recent years, particularly during the coronavirus disease 2019 pandemic. However, studies investigating the detection of other common respiratory pathogens in saliva samples are limited. In this study, nasopharyngeal swabs (NPS), oropharyngeal swabs (OPS), and "hock-a-loogie" saliva (HLS) were collected from 469 patients to detect 13 common respiratory pathogens. Overall positivity rates for NPS (66.1 %), HLS (63.5 %), and OPS (57.8 %) were statistically different (P = 0.028), with an overall concordance of 72.7 %. Additionally, detection rates for NPS (85.9 %) and HLS (83.2 %) for all pathogens were much higher than for OPS (73.3 %). Coronavirus and human rhinovirus were most frequently detected pathogens in NPS (P < 0.001). Mycoplasma pneumoniae was significantly more prevalent in the HLS group (P = 0.008). In conclusion, NPS was a reliable sample type for detecting common respiratory pathogens. HLS was more easily collected and can be used in emergencies or specific conditions. Mixed NPS/OPS and NPS/HLS specimens have the potential to improve detection rates, although OPS testing alone has a relatively high risk for missed detection.

Comprehensive proteomics and platform validation of urinary biomarkers for bladder cancer diagnosis and staging

BACKGROUND

Bladder cancer (BC) is among the most common cancers diagnosed in men in the USA. The current gold standards for the diagnosis of BC are invasive or lack the sensitivity to correctly identify the disease.

METHODS

An aptamer-based screen analyzed the expression of 1317 proteins in BC compared to urology clinic controls. The top hits were subjected to systems biology analyses. Next, 30 urine proteins were ELISA-validated in an independent cohort of 68 subjects. Three of these proteins were next validated in an independent BC cohort of differing ethnicity.

RESULTS

Systems biology analysis implicated molecular functions related to the extracellular matrix, collagen, integrin, heparin, and transmembrane tyrosine kinase signaling in BC susceptibility, with HNF4A and NFKB1 emerging as key molecular regulators. STEM analysis of the dysregulated pathways implicated a functional role for the immune system, complement, and interleukins in BC disease progression. Of 21 urine proteins that discriminated BC from urology clinic controls (UC), urine D-dimer displayed the highest accuracy (0.96) and sensitivity of 97%. Furthermore, 8 urine proteins significantly discriminated MIBC from NMIBC (AUC = 0.75-0.99), with IL-8 and IgA being the best performers. Urine IgA and fibronectin exhibited the highest specificity of 80% at fixed sensitivity for identifying advanced BC.

CONCLUSIONS

Given the high sensitivity (97%) of urine D-dimer for BC, it may have a role in the initial diagnosis or detection of cancer recurrence. On the other hand, urine IL-8 and IgA may have the potential in identifying disease progression during patient follow-up. The use of these biomarkers for initial triage could have a significant impact as the current cystoscopy-based diagnostic and surveillance approach is costly and invasive when compared to a simple urine test.

Hand-Powered Point-of-Care: Centrifugal Microfluidic Platform for Urine Routine Examination (μCUREX)

Urinalysis is one of the simplest and most common medical tests in modern cities. With the assistance of professional technicians and equipment, people in metropolitan areas can effortlessly acquire information about their physiological conditions from traditional clinical laboratories. However, the threshold, including precise benchtop equipment and well-trained personnel, still remains a considerable dilemma for residents in healthcare-poor areas. Hence, it is a crucial and urgent topic to develop a smart and affordable widget to address this challenge. To improve the healthcare rights of residents, we proposed a disposable centrifugal microfluidic urine routine examination platform (named μCUREX) actuated with a modified hand-powered fan. Two parts of urinalysis (sediment test and chemical strip test) were integrated into the μCUREX disc. The influence on sedimentation by variant hand-powered manipulation was simulated using COMSOL. As a result, more than 70% of the sediment can be collected. Moreover, the color change of chemical strip papers (indicators for glucose, pH, protein, and occult blood) was recorded with a 3D-printed studio and analyzed after reaction with chemical-spiked and pH-adjusted artificial and human urine specimens. The whole process can be completed within 10 min, with only 200 μL of urine needed. In conclusion, we successfully constructed an ultra-low-cost point-of-care platform for urinalysis in extremely resource-poor settings. The handy size, high affordability, and user-friendliness of the μCUREX disc provide strong potential and feasibility in solving problems in resource-poor settings. Furthermore, we highly expect the μCUREX platform to improve the level of healthcare in resource-limited areas.

Bleeding in neonates with severe thrombocytopenia: a retrospective cohort study

BACKGROUND

Severe neonatal thrombocytopenia is a rare disease with multiple etiologies. Severe thrombocytopenia with bleeding is life-threatening and has attracted significant attention from clinicians. However, only a few studies have focused on the association between severe thrombocytopenia and bleeding. Thus, this study aimed to describe the neonates' postnatal age at which severe thrombocytopenia was first recognized, clinical characteristics, bleeding patterns, and outcomes and to evaluate the association between minimum platelet count and bleeding.

METHODS

A single-center retrospective cohort study for neonates with severe thrombocytopenia (platelet count ≤ 50 × 10⁹/L) was conducted. Neonates who were admitted to our neonatal intensive care unit between October 2016 and February 2021 and developed severe thrombocytopenia were analyzed. Data were collected retrospectively until the patients were referred to other hospitals, discharged, or deceased.

RESULTS

Among the 5819 neonatal inpatients, 170 with severe thrombocytopenia were included in this study. More than 30% of the patients had severe thrombocytopenia in the first 3 days of life. Among the 118 neonates with bleeding, 47 had more than one type of pathological bleeding. Neonates with very severe thrombocytopenia (point estimate: 53.7%, 95% confidence interval [CI]: 44.2%-63.1%) had a higher incidence rate of cutaneous bleeding than those with severe thrombocytopenia (point estimate: 23.4%, 95% CI: 12.3%-34.4%). The gestational age (median: 36.2 [interquartile range [IQR]: 31.4-39.0] weeks) and birth weight (median: 2310 [IQR: 1213-3210] g) of the major bleeding group were the lowest among no bleeding, minor bleeding, and major bleeding groups. Regression analysis controlled for confounders and confirmed that a lower platelet count (odds ratio [OR]: 2.504 [95% CI: 1.180-5.314], P = 0.017) was associated with a significant increase in the rate of bleeding. Very severe thrombocytopenia (point estimate: 49.1%, 95% CI: 39.6%-58.6%) had a higher rate of platelet transfusion than severe thrombocytopenia (point estimate: 5.7%, 95% CI: 0.7%-10.7%). The mortality rate was higher in neonates with bleeding than in those without bleeding (point estimates with 95% CI: 33.1% [24.4%-41.7%] vs. 7.7% [0.2%-15.2%]).

CONCLUSIONS

These findings describe the incidence of severe thrombocytopenia and demonstrate that a lower platelet count is associated with an increased bleeding rate in patients with severe thrombocytopenia.

A novel technology for home monitoring of lupus nephritis that tracks the pathogenic urine biomarker ALCAM

Introduction

The gold standard for diagnosis of active lupus nephritis (ALN), a kidney biopsy, is invasive with attendant morbidity and cannot be serially repeated. Urinary ALCAM (uALCAM) has shown high diagnostic accuracy for renal pathology activity in ALN patients.

Methods

Lateral flow assays (LFA) for assaying uALCAM were engineered using persistent luminescent nanoparticles, read by a smartphone. The stability and reproducibility of the assembled LFA strips and freeze-dried conjugated nanoparticles were verified, as was analyte specificity.

Results

The LFA tests for both un-normalized uALCAM (AUC=0.93) and urine normalizer (HVEM)-normalized uALCAM (AUC=0.91) exhibited excellent accuracies in distinguishing ALN from healthy controls. The accuracies for distinguishing ALN from all other lupus patients were 0.86 and 0.74, respectively.

Conclusion

Periodic monitoring of uALCAM using this easy-to-use LFA test by the patient at home could potentially accelerate early detection of renal involvement or disease flares in lupus patients, and hence reduce morbidity and mortality.

A Time-Series Metabolomic Analysis of SARS-CoV-2 Infection in a Ferret Model

The global threat of COVID-19 has led to an increased use of metabolomics to study SARS-CoV-2 infections in animals and humans. In spite of these efforts, however, understanding the metabolome of SARS-CoV-2 during an infection remains difficult and incomplete. In this study, metabolic responses to a SAS-CoV-2 challenge experiment were studied in nasal washes collected from an asymptomatic ferret model (n = 20) at different time points before and after infection using an LC-MS-based metabolomics approach. A multivariate analysis of the nasal wash metabolome data revealed several statistically significant features. Despite no effects of sex or interaction between sex and time on the time course of SARS-CoV-2 infection, 16 metabolites were significantly different at all time points post-infection. Among these altered metabolites, the relative abundance of taurine was elevated post-infection, which could be an indication of hepatotoxicity, while the accumulation of sialic acids could indicate SARS-CoV-2 invasion. Enrichment analysis identified several pathways influenced by SARS-CoV-2 infection. Of these, sugar, glycan, and amino acid metabolisms were the key altered pathways in the upper respiratory channel during infection. These findings provide some new insights into the progression of SARS-CoV-2 infection in ferrets at the metabolic level, which could be useful for the development of early clinical diagnosis tools and new or repurposed drug therapies.

Recent Advances in Biosensor Technologies for Point-of-Care Urinalysis

Human urine samples are non-invasive, readily available, and contain several components that can provide useful indicators of the health status of patients. Hence, urine is a desirable and important template to aid in the diagnosis of common clinical conditions. Conventional methods such as dipstick tests, urine culture, and urine microscopy are commonly used for urinalysis. Among them, the dipstick test is undoubtedly the most popular owing to its ease of use, low cost, and quick response. Despite these advantages, the dipstick test has limitations in terms of sensitivity, selectivity, reusability, and quantitative evaluation of diseases. Various biosensor technologies give it the potential for being developed into point-of-care (POC) applications by overcoming these limitations of the dipstick test. Here, we present a review of the biosensor technologies available to identify urine-based biomarkers that are typically detected by the dipstick test and discuss the present limitations and challenges that future development for their translation into POC applications for urinalysis.

Effect of up to 30-days of storage at different temperatures on detection of feline kidney injury molecule-1 in urine

Background

In humans, kidney injury molecule-1 (KIM-1) is a biomarker of acute kidney injury that can be quantified in urine. Preliminary investigation in cats with experimentally induced acute kidney injury showed that KIM-1 urine concentration correlated with kidney injury histopathology scores. A lateral flow assay (LFA) has recently become available for patient-side feline KIM-1 measurement. In vitro parameters of the assay have not yet been determined. The objectives of this study were to determine detection of KIM-1 in urine stored at different temperatures over time, to establish the linear range of the LFA, and to assess the intra-assay repeatability of measurements. 

Results

Ten urine samples with a range of KIM-1 concentrations were stored at room temperature (22^o C), 4^o C or -20^o C, and tested with the LFA on days 0, 1, 2, 3, 7, 14, and 30. The concentration of KIM-1 in samples was not significantly different from the day 0 value, except one sample that had been stored for 30 days at room temperature yielded a significantly higher value. The assay results had a correlation coefficient of 0.922. The mean coefficient of variation for all samples was 15.7%. The slope of the curve of expected versus measured values in samples diluted two-fold nine times was 0.908, and results were linear over all dilutions.

Conclusions

The LFA for feline KIM-1 yields consistent results from stored urine samples. These characteristics will allow for KIM-1 to be measured retrospectively if immediate testing is not feasible. Within assay precision was high, and linearity over 9 logs of dilution suggests suitability for a range of subclinical and clinical kidney injuries.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12917-022-03489-w.

Predictive System Implementation to Improve the Accuracy of Urine Self-Diagnosis with Smartphones: Application of a Confusion Matrix-Based Learning Model through RGB Semiquantitative Analysis

Urinalysis, an elementary chemical reaction-based method for analyzing color conversion factors, facilitates examination of pathological conditions in the human body. Recently, considerable urinalysis-centered research has been conducted on the analysis of urine dipstick colors using smartphone cameras; however, such methods have a drawback: the problem of reproducibility of accuracy through quantitative analysis. In this study, to solve this problem, the function values for each concentration of a range of analysis factors were implemented in an algorithm through urine dipstick RGB semi-quantitative color analysis to enable real-time results. Herein, pH, glucose, ketones, hemoglobin, bilirubin, protein (albumin), and nitrites were selected as analysis factors, and the accuracy levels of the existing equipment and the test application were compared and evaluated using artificial urine. In the semi-quantitative analysis, the red (R), green (G), and blue (B) characteristic values were analyzed by extracting the RGB characteristic values of the analysis factors for each concentration of artificial urine and obtaining linear function values. In addition, to improve the reproducibility of detection accuracy, the measurement value of the existing test equipment was set to an absolute value; using a machine-learning technique, the confusion matrix, we attempted to stabilize test results that vary with environment.

Design of Gold Nanoparticle Vertical Flow Assays for Point-of-Care Testing

Vertical flow assays (VFAs) or flow-through assays have emerged as an alternate type of paper-based assay due to their faster detection time, larger sample volume capacity, and significantly higher multiplexing capabilities. They have been successfully employed to detect several different targets (polysaccharides, protein, and nucleic acids), although in a limited number of samples (serum, whole blood, plasma) compared to the more commonly known lateral flow assays (LFAs). The operation of a VFA relies mainly on gravity, coupled with capillary action or external force to help the sample flow through layers of stacked pads. With recent developments in this field, multiple layers of pads and signal readers have been optimized for more user-friendly operation, and VFAs have achieved a lower limit of detection for various analytes than the gold-standard methods. Thus, compared to the more widely used LFA, the VFA demonstrates certain advantages and is becoming an increasingly popular platform for obtaining qualitative and quantitative results in low-resource settings. Considering the wide application of gold nanoparticles (GNPs) in VFAs, we will mostly discuss (1) the design of GNP-based VFA along with its associated advantages/disadvantages, (2) fabrication and optimization of GNP-based VFAs for applications, and (3) the future outlook of flow-based assays for point-of-care testing (POCT) diagnostics.

Plasmonic nanosensors for point-of-care biomarker detection

Advancement of materials along with their fascinating properties play increasingly important role in facilitating the rapid progress in medicine. An excellent example is the recent development of biosensors based on nanomaterials that induce surface plasmon effect for screening biomarkers of various diseases ranging from cancer to Covid-19. The recent global pandemic re-confirmed the trend of real-time diagnosis in public health to be in point-of-care (POC) settings that can screen interested biomarkers at home, or literally anywhere else, at any time. Plasmonic biosensors, thanks to its versatile designs and extraordinary sensitivities, can be scaled into small and portable devices for POC diagnostic tools. In the meantime, efforts are being made to speed up, simplify and lower the cost of the signal readout process including converting the conventional heavy laboratory instruments into lightweight handheld devices. This article reviews the recent progress on the design of plasmonic nanomaterial-based biosensors for biomarker detection with a perspective of POC applications. After briefly introducing the plasmonic detection working mechanisms and devices, the selected highlights in the field focusing on the technology's design including nanomaterials development, structure assembly, and target applications are presented and analyzed. In parallel, discussions on the sensor's current or potential applicability in POC diagnosis are provided. Finally, challenges and opportunities in plasmonic biosensor for biomarker detection, such as the current Covid-19 pandemic and its testing using plasmonic biosensor and incorporation of machine learning algorithms are discussed.

Independence of Urinary Symptoms and Urinary Dipstick Results in Voiders With Neurogenic Bladder

Background

Urinary symptoms and urinary tract infection (UTI) are frequent and burdensome problems associated with neurogenic lower urinary tract dysfunction.

Objectives

To determine whether an association exists between urinary symptoms and urine dipstick results among individuals with spinal cord injury (SCI) or multiple sclerosis (MS).

Methods

Prospective 12-month cohort study of 76 participants with SCI or MS who manage their bladders by voiding. Eligibility criteria included adults ≥18 years old, at least three UTIs since diagnosis, and residence in the United States. Participants completed the Urinary Symptoms Questionnaire for Neurogenic Bladder-Voider version (USQNB-V) biweekly (26 assessments) and tested their urine by dipstick at the same time. Symptom burden was estimated based on endorsements of USQNB-V symptoms classified as clinically actionable (9), bladder function (8), and urine quality (4). Urine dipstick results assessed were leukocyte esterase (LE) and nitrite (NIT).

Results

Participants were stratified into four groups based on etiology of neurologic dysfunction and whether they ever experienced any urinary symptoms (USx): SCI+USx (n = 14), SCI+NoUSx (n = 5), MS+USx (n = 32), and MS+NoUSx (n = 25). In descending order, symptom burden was greatest for the MS+USx group, followed by both SCI groups; it was lowest for MS+NoUSx. We assessed multiple definitions of "positive" dipstick and found evidence of independence of USQNB-V symptoms and urinary dipstick results with each definition. In each group, the median (and majority) of strong positive dipsticks did not coincide with any symptoms.

Conclusion

Among people with SCI or MS who void, self-administered urine dipstick results and urinary symptom reporting contribute independent information for clinical decision making.

Toilet-based continuous health monitoring using urine

Regular health monitoring can result in early detection of disease, accelerate the delivery of medical care and, therefore, considerably improve patient outcomes for countless medical conditions that affect public health. A substantial unmet need remains for technologies that can transform the status quo of reactive health care to preventive, evidence-based, person-centred care. With this goal in mind, platforms that can be easily integrated into people's daily lives and identify a range of biomarkers for health and disease are desirable. However, urine - a biological fluid that is produced in large volumes every day and can be obtained with zero pain, without affecting the daily routine of individuals, and has the most biologically rich content - is discarded into sewers on a regular basis without being processed or monitored. Toilet-based health-monitoring tools in the form of smart toilets could offer preventive home-based continuous health monitoring for early diagnosis of diseases while being connected to data servers (using the Internet of Things) to enable collection of the health status of users. In addition, machine learning methods can assist clinicians to classify, quantify and interpret collected data more rapidly and accurately than they were able to previously. Meanwhile, challenges associated with user acceptance, privacy and test frequency optimization should be considered to facilitate the acceptance of smart toilets in society.

Biosensor-Enabled Multiplexed On-Site Therapeutic Drug Monitoring of Antibiotics

Personalized antibiotherapy ensures that the antibiotic concentration remains in the optimal therapeutic window to maximize efficacy, minimize side effects, and avoid the emergence of drug resistance due to insufficient dosing. However, such individualized schemes need frequent sampling to tailor the blood antibiotic concentrations. To optimally integrate therapeutic drug monitoring (TDM) into the clinical workflow, antibiotic levels can either be measured in blood using point-of-care testing (POCT), or can rely on noninvasive sampling. Here, a versatile biosensor with an antibody-free assay for on-site TDM is presented. The platform is evaluated with an animal study, where antibiotic concentrations are quantified in different matrices including whole blood, plasma, urine, saliva, and exhaled breath condensate (EBC). The clearance and the temporal evaluation of antibiotic levels in EBC and plasma are demonstrated. Influence of matrix effects on measured drug concentrations is determined by comparing the plasma levels with those in noninvasive samples. The system's potential for blood-based POCT is further illustrated by tracking ß-lactam concentrations in untreated blood samples. Finally, multiplexing capabilities are explored successfully for multianalyte/sample analysis. By enabling a rapid, low-cost, sample-independent, and multiplexed on-site TDM, this system can shift the paradigm of "one-size-fits-all" strategy.

Managing recurrent urinary tract infections in kidney transplant recipients using smartphone assisted urinalysis test

BACKGROUND

Urinary tract infection is the most frequent infectious complication in allograft recipients with poor outcomes. The study aimed to assess the effect of self-testing urine dipsticks at home, with the assistance of smartphone technology, on the occurrence of urinary tract infection (UTI)-associated complications and frequency and length of hospital admissions.

METHOD

We performed a retrospective cohort study of kidney transplant recipients with a history of recurrent UTI who used a newly introduced smartphone-assisted dipsticks urinalysis test for self-monitoring. Participants self-administered the home urinalysis test with symptom onset. Antibiotics were prescribed if an infection was suspected, and home urinalysis was positive. The incidence of urinary infections, hospitalisations, and complications was evaluated before and during the home urinalysis period. Remote and face-to-face interactions with healthcare personnel were also assessed (cases acted as their controls).

RESULTS

Nineteen participants were included in the study. A total of 89.5% were females. Ninety home urinalysis tests were conducted over a mean period of 7 months. Sixty-one of these were pre-antibiotic. A total of 42.2% of all tests and 47.5% of the pre-antibiotic tests were positive. UTI-related hospitalisations were lower by 75% during the home urinalysis period; mean 1.26 (0.8-1.6) versus 0.32 (-0.01-0.6). The incidence of infection-related complications was also 65% lower; mean 1.52 (0.8-2.2) versus 0.52 (-0.2-1.2) during the same period. The number of face-to-face interactions was slightly lower; mean 1.9 (1.1-2.2) versus 1.7 (0.6-2.8), with more remote interactions; mean 6.0 (3.7-8.5) versus 10.4 (6.5-14.3), during smartphone urinalysis. Fifty per cent of antibiotic-treated UTI episodes had antibiotics within 24 h, rising to 82% within 48 h of a test.

CONCLUSION

Smartphone-assisted home urinalysis enabled remote management of UTI in a high-risk population. Outcomes point to a reduction in UTI complications and hospitalisations.

Point-of-care testing technologies for the home in chronic kidney disease: a narrative review

Point-of-care testing (POCT) performed by the patient at home, paired with eHealth technologies, offers a wealth of opportunities to develop individualized, empowering clinical pathways. The non-dialysis-dependent chronic kidney disease (CKD) patient who is at risk of or may already be suffering from a number of the associated complications of CKD represents an ideal patient group for the development of such initiatives. The current coronavirus disease 2019 pandemic and drive towards shielding vulnerable individuals have further highlighted the need for home testing pathways. In this narrative review we outline the evidence supporting remote patient management and the various technologies in use in the POCT setting. We then review the devices currently available for use in the home by patients in five key areas of renal medicine: anaemia, biochemical, blood pressure (BP), anticoagulation and diabetes monitoring. Currently there are few devices and little evidence to support the use of home POCT in CKD. While home testing in BP, anticoagulation and diabetes monitoring is relatively well developed, the fields of anaemia and biochemical POCT are still in their infancy. However, patients' attitudes towards eHealth and home POCT are consistently positive and physicians also find this care highly acceptable. The regulatory and translational challenges involved in the development of new home-based care pathways are significant. Pragmatic and adaptable trials of a hybrid effectiveness-implementation design, as well as continued technological POCT device advancement, are required to deliver these innovative new pathways that our patients desire and deserve.

Design and Functionalization of a µPAD for the Enzymatic Determination of Nitrate in Urine

In this work, the design of a microfluidic paper-based analytical device (μPAD) for the quantification of nitrate in urine samples was described. Nitrate monitoring is highly relevant due to its association to some diseases and health conditions. The nitrate determination was achieved by combining the selectivity of the nitrate reductase enzymatic reaction with the colorimetric detection of nitrite by the well-known Griess reagent. For the optimization of the nitrate determination μPAD, several variables associated with the design and construction of the device were studied. Furthermore, the interference of the urine matrix was evaluated, and stability studies were performed, under different conditions. The developed μPAD enabled us to obtain a limit of detection of 0.04 mM, a limit of quantification of 0.14 mM and a dynamic concentration range of 0.14-1.0 mM. The designed μPAD proved to be stable for 24 h when stored at room temperature in air or vacuum atmosphere, and 60 days when stored in vacuum at -20 °C. The accuracy of the nitrate μPAD measurements was confirmed by analyzing four certified samples (prepared in synthetic urine) and performing recovery studies using urine samples.

Metabolic Profiling from an Asymptomatic Ferret Model of SARS-CoV-2 Infection

Coronavirus disease (COVID-19) is a contagious respiratory disease that is causing significant global morbidity and mortality. Understanding the impact of the Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) infection on the host metabolism is still in its infancy but of great importance. Herein, we investigated the metabolic response during viral shedding and post-shedding in an asymptomatic SARS-CoV-2 ferret model (n = 6) challenged with two SARS-CoV-2 isolates. Virological and metabolic analyses were performed on (minimally invasive) collected oral swabs, rectal swabs, and nasal washes. Fragments of SARS-CoV-2 RNA were only found in the nasal wash samples in four of the six ferrets, and in the samples collected 3 to 9 days post-infection (referred to as viral shedding). Central carbon metabolism metabolites were analyzed during viral shedding and post-shedding periods using a dynamic Multiple Reaction Monitoring (dMRM) database and method. Subsequent untargeted metabolomics and lipidomics of the same samples were performed using a Liquid Chromatography Quadrupole Time-of-Flight Mass Spectrometry (LC-QToF-MS) methodology, building upon the identified differentiated central carbon metabolism metabolites. Multivariate analysis of the acquired data identified 29 significant metabolites and three lipids that were subjected to pathway enrichment and impact analysis. The presence of viral shedding coincided with the challenge dose administered and significant changes in the citric acid cycle, purine metabolism, and pentose phosphate pathways, amongst others, in the host nasal wash samples. An elevated immune response in the host was also observed between the two isolates studied. These results support other metabolomic-based findings in clinical observational studies and indicate the utility of metabolomics applied to ferrets for further COVID-19 research that advances early diagnosis of asymptomatic and mild clinical COVID-19 infections, in addition to assessing the effectiveness of new or repurposed drug therapies.

Urine protein biomarkers of bladder cancer arising from 16-plex antibody-based screens

Purpose: The purpose of this study is to identify novel urine protein biomarkers of bladder cancer using a Luminex based screening platform.

Materials and Methods: The current study examines urine samples from 66 subjects, comprised of 31 Urology clinic controls and 35 bladder cancer patients, using a Luminex based screening platform. ELISA validation was carried out for the top 4 prospective urine biomarkers using an independent cohort of 20 Urology clinic controls and 60 bladder cancer (BC) subjects.

Results: Of the 16 proteins screened by Luminex, 10 showed significant elevation in BC compared to the controls. Eight of these urine proteins were able to differentiate BC from control urine with ROC AUC values exceeding 0.70 at p < 0.0001, with specificity values exceeding 0.9. Upon ELISA validation, urine IL-1α, IL-1ra, and IL-8 were able to distinguish control urine from urine drawn from various bladder cancer stages, with IL-8 being the best discriminator. Compared to members of the IL-1 cytokine family, urine IL-8 was also best at discriminating T1 and/or T2–T4 from Ta BC (ROC AUC ≥ 0.83), as well as high grade from low grade BC (ROC AUC ≥ 0.82).

Conclusions: These findings suggest that urine IL-1α, IL-1ra and IL-8 are useful indicators of bladder cancer. Urine IL-8 not only distinguishes bladder cancer from controls, it also discriminates high grade from low grade disease, and the successive clinical stages of bladder cancer. While supportive of previous reports, these findings warrant further analysis in prospective cohorts.

Label-Free Protein Detection by Micro-Acoustic Biosensor Coupled with Electrical Field Sorting. Theoretical Study in Urine Models

Diagnostic devices for point-of-care (POC) urine analysis (urinalysis) based on microfluidic technology have been actively developing for several decades as an alternative to laboratory based biochemical assays. Urine proteins (albumin, immunoglobulins, uromodulin, haemoglobin etc.) are important biomarkers of various pathological conditions and should be selectively detected by urinalysis sensors. The challenge is a determination of different oligomeric forms of the same protein, e.g., uromodulin, which have similar bio-chemical affinity but different physical properties. For the selective detection of different types of proteins, we propose to use a shear bulk acoustic resonator sensor with an additional electrode on the upper part of the bioliquid-filled channel for protein electric field manipulation. It causes modulation of the protein concentration over time in the near-surface region of the acoustic sensor, that allows to distinguish proteins based on their differences in diffusion coefficients (or sizes) and zeta-potentials. Moreover, in order to improve the sensitivity to density, we propose to use structured sensor interface. A numerical study of this approach for the detection of proteins was carried out using the example of albumin, immunoglobulin, and oligomeric forms of uromodulin in model urine solutions. In this contribution we prove the proposed concept with numerical studies for the detection of albumin, immunoglobulin, and oligomeric forms of uromodulin in urine models.

Quantum Dots: An Emerging Tool for Point-of-Care Testing

Quantum dots (QDs) are semiconductor crystals in the nanodimension having unique optical and electronic properties that differ from bulk material due to quantum mechanics. The QDs have a narrow emission peak, size-dependent emission wavelength, and broad excitation range which can be utilized for diverse biomedical applications such as molecular imaging, biosensing, and diagnostic systems. This article reviews the current developments of biomedical applications of QDs with special reference to point-of-care testing.