[Lithogenic risk in patients from Paraguay with urolithiasis]. / Perfil de riesgo litogénico en pacientes con urolitiasis en Paraguay.

UNLABELLED: The lithogenic risk profile is a graphical representation of metabolic factors and urinary saturation involved in the stone formation with their respective critical values. AIM: To determine the lithogenic risk profile in patients with urolithiasis. MATERIAL AND METHODS: Personal data such as anthropometric, history of diseases and family history of urolithiasis were recorded. Different compounds acting as promoters or inhibitors of crystallization were measured in serum and urine samples, and the data obtained were used to calculate urinary saturation using Equil software. RESULTS: We included 30 men and 43 women with a median age of 45 (34-54) years. Overweight and family history of urolithiasis was reported in 63 and 32% respectively. Crystallization risk was detected in 74% of participants. The most common urinary abnormalities were hypocitraturia in 48% and hypercalciuria in 40%. CONCLUSIONS: The lithogenic profile revealed urinary saturation compatible with crystallization risk in 74% of the studied patients.

Label-free impedimetric aptasensor for ochratoxin-A detection using iridium oxide nanoparticles.

In this article, a novel aptasensor for ochratoxin A (OTA) detection based on a screen-printed carbon electrode (SPCE) modified with polythionine (PTH) and iridium oxide nanoparticles (IrO2 NPs) is presented. The electrotransducer surface is modified with an electropolymerized film of PTH followed by the assembly of IrO2 NPs on which the aminated aptamer selective to OTA is exchanged with the citrate ions surrounding IrO2 NPs via electrostatic interactions with the same surface. Electrochemical impedance spectroscopy (EIS) in the presence of the [Fe(CN)6](-3/-4) redox probe is employed to characterize each step in the aptasensor assay and also for label-free detection of OTA in a range between 0.01 and 100 nM, obtaining one of the lowest limits of detection reported so far for label-free impedimetric detection of OTA (14 pM; 5.65 ng/kg). The reported system also exhibits a high reproducibility, a good performance with a white wine sample, and an excellent specificity against another toxin present in such sample.

Harnessing Bioluminescent Bacteria to Develop an Enzymatic-free Enzyme-linked immunosorbent assay for the Detection of Clinically Relevant Biomarkers.

Enzyme-linked immunosorbent assay (ELISA) is the gold standard technique for measuring protein biomarkers due to its high sensitivity, specificity, and throughput. Despite its success, continuous advancements in ELISA and immunoassay formats are crucial to meet evolving global challenges and to address new analytical needs in diverse applications. To expand the capabilities and applications of immunoassays, we introduce a novel ELISA-like assay that we call Bioluminescent-bacteria-linked immunosorbent assay (BBLISA). BBLISA is an enzyme-free assay that utilizes the inner filter effect between the bioluminescent bacteriaAllivibrio fischeriand metallic nanoparticles (gold nanoparticles and gold iridium oxide nanoflowers) as molecular absorbers. Functionalizing these nanoparticles with antibodies induces their accumulation in wells upon binding to molecular targets, forming the classical immune-sandwich complex. Thanks to their ability to adsorb the light emitted by the bacteria, the nanoparticles can suppress the bioluminescence signal, allowing the rapid quantification of the target. To demonstrate the bioanalytical properties of the novel immunoassay platform, as a proof of principle, we detected two clinically relevant biomarkers (human immunoglobulin G and SARS-CoV-2 nucleoprotein) in human serum, achieving the same sensitivity and precision as the classic ELISA. We believe that BBLISA can be a promising alternative to the standard ELISA techniques, offering potential advancements in biomarker detection and analysis by combining nanomaterials with a low-cost, portable bioluminescent platform.

A community-based study on the prevalence of spondyloarthritis and inflammatory back pain in Mexicans.

BACKGROUND: The prevalence of spondyloarthritis (SpA) varies across populations. In Mexicans, the prevalence of SpA is still unknown. OBJECTIVE: The objective of this study was to determine the prevalence of SpA in the community as well as that of inflammatory back pain (IBP) and ankylosing spondylitis (AS). METHODS: We identified individuals older than 18 years with nontraumatic back pain (BP) in a door-to-door nurse survey using the Community Oriented Program for the Control of Rheumatic Diseases. Then, general physicians and rheumatology fellows selected those likely to have IBP (Berlin criteria). Finally, 2 expert rheumatologists assessed IBP individuals according to clinical data and classification criteria and requested HLA-B27 and radiographic studies to determine the clinical condition of the individual and SpA (European SpA Study Group) classification. RESULTS: The prevalence of BP among 4059 individuals was 14.6% (95% confidence interval [CI], 13.6-15.8). The prevalence of IBP and SpA was 1.3% (95% CI, 1.0-1.7) and 0.6% (95% CI, 0.4-0.9), respectively. Ankylosing spondylitis prevalence was 0.1% (95% CI, 0.02-0.2). Inflammatory back pain and SpA percentage of males and females was similar. The percentage of individuals with IBP according to the 2 experts was lower than that determined by general physicians and rheumatology fellows, but all cases with HLA-B27, radiographic sacroiliitis, SpA, and AS had previous IBP confirmation by the expert. CONCLUSIONS: The prevalence and sex distribution of patients classified with SpA in this community study--as well as that of patients diagnosed with AS--are consistent with those found in recent studies. Expert assessment of individuals with positive responses to questionnaires is relevant for the classification of IBP and SpA.

Selection and characterisation of bioreceptors to develop nanoparticle-based lateral-flow immunoassays in the context of the SARS-CoV-2 outbreak.

This manuscript aims at raising the attention of the scientific community to the need for better characterised bioreceptors for fast development of point-of-care diagnostic devices able to support mass frequency testing. Particularly, we present the difficulties encountered in finding suitable antibodies for the development of a lateral flow assay for detecting the nucleoprotein of SARS-CoV-2.

Prevalence of back pain in the community. A COPCORD-based study in the Mexican population.

OBJECTIVE: Back pain (BP) is frequent in the community; its prevalence in México is 6%. Our objective was to determine the prevalence of BP in Mexican communities and determine its most important characteristics. METHODS: A cross-sectional study of individuals aged > 18 years was conducted in Mexico City and in urban communities in the state of Nuevo León. Sampling in Mexico City was based on community census and in Nuevo León, on stratified, balanced, and random sampling. Procedures included a door-to-door survey, using the Community Oriented Program for the Control of Rheumatic Diseases, to identify individuals with BP > 1 on a visual analog scale in the last 7 days. General practitioners/rheumatology fellows confirmed and characterized BP symptoms. RESULTS: In all, 8159 individuals (mean age 43.7 yrs, two-thirds female) were surveyed and 1219 had BP. The prevalence of nontraumatic BP in the last 7 days was 8.0% (95% CI 7.5-8.7). The mean age of these individuals was 42.7 years, and 61.9% were female. Thirty-seven percent had inflammatory BP [prevalence of 3.0% (95% CI 2.7-3.4)]. Compared with the state of Nuevo Léon, the characteristics and consequences of BP in Mexico City were more severe. In logistic regression analysis, living in Mexico City, having a paid job, any kind of musculoskeletal pain, high pain intensity, and obesity among other variables were associated with BP. CONCLUSION: The prevalence of nontraumatic BP in the last 7 days in urban communities in México is 8.0%. However, clinical features and consequences differed among the communities studied, suggesting a role for local factors in BP.

Miniaturized Electrochemical Sensors to Monitor Fetal Hypoxia and Acidosis in a Pregnant Sheep Model.

Perinatal asphyxia is a major cause of severe brain damage and death. For its prenatal identification, Doppler ultrasound has been used as a surrogate marker of fetal hypoxia. However, Doppler evaluation cannot be performed continuously. We have evaluated the performance of a miniaturized multiparametric sensor aiming to evaluate tissular oxygen and pH changes continuously in an umbilical cord occlusion (UCO) sheep model. The electrochemical sensors were inserted in fetal hindlimb skeletal muscle and electrochemical signals were recorded. Fetal hemodynamic changes and metabolic status were also monitored during the experiment. Additionally, histological assessment of the tissue surrounding the sensors was performed. Both electrochemical sensors detected the pO2 and pH changes induced by the UCO and these changes were correlated with hemodynamic parameters as well as with pH and oxygen content in the blood. Finally, histological assessment revealed no signs of alteration on the same day of insertion. This study provides the first evidence showing the application of miniaturized multiparametric electrochemical sensors detecting changes in oxygen and pH in skeletal muscular tissue in a fetal sheep model.

Fetal ischemia monitoring with in vivo implanted electrochemical multiparametric microsensors.

Under intrauterine growth restriction (IUGR), abnormal attainment of the nutrients and oxygen by the fetus restricts the normal evolution of the prenatal causing in many cases high morbidity being one of the top-ten causes of neonatal death. The current gold standards in hospitals to detect this relevant problem is the clinical observation by echography, cardiotocography and Doppler. These qualitative techniques are not conclusive and requires risky invasive fetal scalp blood testing and/or amniocentesis. We developed micro-implantable multiparametric electrochemical sensors for measuring ischemia in real time in fetal tissue and vascular. This implantable technology is designed to continuous monitoring for an early detection of ischemia to avoid potential fetal injury. Two miniaturized electrochemical sensors were developed based on oxygen and pH detection. The sensors were optimized in vitro under controlled concentration, to assess the selectivity and sensitivity required. The sensors were then validated in vivo in the ewe fetus model, by means of their insertion in the muscle leg and inside the iliac artery of the fetus. Ischemia was achieved by gradually obstructing the umbilical cord to regulate the amount of blood reaching the fetus. An important challenge in fetal monitoring is the detection of low levels of oxygen and pH changes under ischemic conditions, requiring high sensitivity sensors. Significant differences were observed in both; pH and pO2 sensors under changes from normoxia to hypoxia states in the fetus tissue and vascular with both sensors. Herein, we demonstrate the feasibility of the developed sensors for future fetal monitoring in medical applications.

in vivo Monitoring with micro-implantable hypoxia sensor based on tissue acidosis.

Hypoxia is a common medical problem, sometimes difficult to detect and caused by different situations. Control of hypoxia is of great medical importance and early detection is essential to prevent life threatening complications. However, the few current methods are invasive, expensive, and risky. Thus, the development of reliable and accurate sensors for the continuous monitoring of hypoxia is of vital importance for clinical monitoring. Herein, we report an implantable sensor to address these needs. The developed device is a low-cost, miniaturised implantable electrochemical sensor for monitoring hypoxia in tissue by means of pH detection. This technology is based on protonation/deprotonation of polypyrrole conductive polymer. The sensor was optimized in vitro and tested in vivo intramuscularly and ex vivo in blood in adult rabbits with respiration-induced hypoxia and correlated with the standard device ePOCTM. The sensor demonstrated excellent sensitivity and reproducibility; 46.4 ± 0.4 mV/pH in the pH range of 4-9 and the selectivity coefficient exhibited low interference activity in vitro. The device was linear (R2 = 0.925) with a low dispersion of the values (n = 11) with a cut-off of 7.1 for hypoxia in vivo and ex vivo. Statistics with one-way ANOVA (α = 0.05), shows statistical differences between hypoxia and normoxia states and the good performance of the pH sensor, which demonstrated good agreement with the standard device. The sensor was stable and functional after 18 months. The excellent results demonstrated the feasibility of the sensors in real-time monitoring of intramuscular tissue and blood for medical applications.

The Microbiome Meets Nanotechnology: Opportunities and Challenges in Developing New Diagnostic Devices.

Monitoring of the human microbiome is an emerging area of diagnostics for personalized medicine. Here, the potential of different nanomaterials and nanobiosensing technologies is reviewed for the development of novel diagnostic devices for the detection and measurement of microbiome-related biomarkers. Moreover, the current and future landscape of microbiome-based diagnostics is defined by exploring the advantages and disadvantages of current nanotechnology-based approaches, especially in the context of developing point-of-care (PoC) devices that would meet the international guidelines known as REASSURED (Real-time connectivity; Ease of specimen collection; Affordability; Sensitivity; Specificity; User-friendliness; Rapid & robust operation; Equipment-free; and Deliverability). Finally, the strategies of the latest international scientific consortia working in this field are analyzed, the current microbiome diagnostics market are reported and the principal ethical, legal, and societal issues related to microbiome R&D and innovation are discussed.

Nanodiagnostics to Face SARS-CoV-2 and Future Pandemics: From an Idea to the Market and Beyond.

The COVID-19 pandemic made clear how our society requires quickly available tools to address emerging healthcare issues. Diagnostic assays and devices are used every day to screen for COVID-19 positive patients, with the aim to decide the appropriate treatment and containment measures. In this context, we would have expected to see the use of the most recent diagnostic technologies worldwide, including the advanced ones such as nano-biosensors capable to provide faster, more sensitive, cheaper, and high-throughput results than the standard polymerase chain reaction and lateral flow assays. Here we discuss why that has not been the case and why all the exciting diagnostic strategies published on a daily basis in peer-reviewed journals are not yet successful in reaching the market and being implemented in the clinical practice.

Tutorial: design and fabrication of nanoparticle-based lateral-flow immunoassays.

Lateral-flow assays (LFAs) are quick, simple and cheap assays to analyze various samples at the point of care or in the field, making them one of the most widespread biosensors currently available. They have been successfully employed for the detection of a myriad of different targets (ranging from atoms up to whole cells) in all type of samples (including water, blood, foodstuff and environmental samples). Their operation relies on the capillary flow of the sample throughout a series of sequential pads, each with different functionalities aiming to generate a signal to indicate the absence/presence (and, in some cases, the concentration) of the analyte of interest. To have a user-friendly operation, their development requires the optimization of multiple, interconnected parameters that may overwhelm new developers. In this tutorial, we provide the readers with: (i) the basic knowledge to understand the principles governing an LFA and to take informed decisions during lateral flow strip design and fabrication, (ii) a roadmap for optimal LFA development independent of the specific application, (iii) a step-by-step example procedure for the assembly and operation of an LF strip for the detection of human IgG and (iv) an extensive troubleshooting section addressing the most frequent issues in designing, assembling and using LFAs. By changing only the receptors, the provided example procedure can easily be adapted for cost-efficient detection of a broad variety of targets.

Micro-needle implantable electrochemical oxygen sensor: ex-vivo and in-vivo studies.

Oxygen is vital for energy metabolism in mammals and the variability of the concentration is considered a clinical alert for a wide range of metabolic malfunctions in medicine. In this article, we describe the development and application of a micro-needle implantable platinum-based electrochemical sensor for measuring partial pressure of oxygen in intramuscular tissue (in-vivo) and vascular blood (ex-vivo). The Pt-Nafion® sensor was characterized morphological and electrochemically showing a higher sensitivity of -2.496 nA/mmHg (-1.495 nA/µM) when comparing with its bare counterpart. Our sensor was able to discriminate states with different oxygen partial pressures (pO2) for ex-vivo (blood) following the same trend of the commercial gas analyzer used as standard. For in-vivo (intramuscular) experiments, since there is not a gold standard for measuring pO2 in tissue, it was not possible to correlate the obtained currents with the pO2 in tissue. However, our sensor was able to detect clear statistical differences of O2 between hyperoxia and hypoxia states in tissue.

A vertical flow paper-microarray assay with isothermal DNA amplification for detection of Neisseria meningitidis.

Paper-based biosensors offer a promising technology to be used at the point of care, enabled by good performance, convenience and low-cost. In this article, we describe a colorimetric vertical-flow DNA microarray (DNA-VFM) that takes advantage of the screening capability of DNA microarrays in a paper format together with isothermal amplification by means of Recombinase Polymerase Amplification (RPA). Different assay parameters such as hybridization buffer, flow rate, printing buffer and capture probe concentration were optimized. A limit of detection (LOD) of 4.4 nM was achieved as determined by tabletop scanning. The DNA-VFM was applied as a proof of concept for detection of Neisseria meningitidis, a primary cause of bacterial meningitis. The LOD was determined to be between 38 and 2.1 × 106 copies/VFMassay, depending on the choice of DNA capture probes. The presented approach provides multiplex capabilities of DNA microarrays in a paper-based format for future point-of-care applications.

Electrochemically reduced graphene and iridium oxide nanoparticles for inhibition-based angiotensin-converting enzyme inhibitor detection.

In this work, a novel biosensor based on electrochemically reduced graphene oxide and iridium oxide nanoparticles for the detection of angiotensin-converting enzyme inhibitor drug, captopril, is presented. For the preparation of the biosensor, tyrosinase is immobilized onto screen printed electrode by using 1-Ethyl-3-(3-dimethylaminopropyl)-carbodiimide and N-Hydroxysuccinimide coupling reagents, in electrochemically reduced graphene oxide and iridium oxide nanoparticles matrix. Biosensor response is characterized towards catechol, in terms of graphene oxide concentration, number of cycles to reduce graphene oxide, volume of iridium oxide nanoparticles and tyrosinase solution. The designed biosensor is used to inhibit tyrosinase activity by Captopril, which is generally used to treat congestive heart failure. It is an angiotensin-converting enzyme inhibitor that operates via chelating copper at the active site of tyrosinase and thioquinone formation. The captopril detections using both inhibition ways are very sensitive with low limits of detection: 0.019µM and 0.008µM for chelating copper at the active site of tyrosinase and thioquinone formation, respectively. The proposed methods have been successfully applied in captopril determination in spiked human serum and pharmaceutical dosage forms with acceptable recovery values.

Health care workers' perceptions of point-of-care testing in a low-income country-A qualitative study in Southwestern Uganda.

BACKGROUND: Point-of-care (POC) tests have become increasingly available and more widely used in recent years. They have been of particular importance to low-income settings, enabling them with clinical capacities that had previously been limited. POC testing programs hold a great potential for significant improvement in low-income health systems. However, as most POC tests are developed in high-income countries, disengagement between developers and end-users inhibit their full potential. This study explores perceptions of POC test end-users in a low-income setting, aiming to support the development of novel POC tests for low-income countries. METHODS: A qualitative study was conducted in Mbarara District, Southwestern Uganda, in October 2014. Fifty health care workers were included in seven focus groups, comprising midwives, laboratory technicians, clinical and medical officers, junior and senior nurses, and medical doctors. Discussions were audio-recorded and transcribed verbatim. Transcripts were coded through a data-driven approach for qualitative content analysis. RESULTS: Nineteen different POC tests were identified as currently being in use. While participants displayed being widely accustomed to and appreciative of the use of POC tests, they also assessed the use and characteristics of current tests as imperfect. An ideal POC test was characterized as being adapted to local conditions, thoughtfully implemented in the specific health system, and capable of improving the care of patients. Tests for specific medical conditions were requested. Opinions differed with regard to the ideal distribution of POC tests in the local health system. CONCLUSION: POC tests are commonly used and greatly appreciated in this study setting. However, there are dissatisfactions with current POC tests and their use. To maximize benefit, stakeholders need to include end-user perspectives in the development and implementation of POC tests. Insights from this study will influence our ongoing efforts to develop POC tests that will be particularly usable in low-income settings.

Antithyroid drug detection using an enzyme cascade blocking in a nanoparticle-based lab-on-a-chip system.

A methimazole (MT) biosensor based on a nanocomposite of magnetic nanoparticles (MNPs) functionalized with iridium oxide nanoparticles (IrOx NPs) and tyrosinase (Tyr) immobilized onto screen printed electrode (SPE) by using a permanent magnet is presented. This system is evaluated in batch mode via chelating copper at the active site of tyrosinase and in flow mode by thioquinone formation. The MT detection in flow mode is achieved using a hybrid polydimethylsiloxane/polyester amperometric lab-on-a-chip (LOC) microsystem with an integrated SPE. Both systems are very sensitive with low limit of detection (LOD): 0.006 µM and 0.004 µM for batch and flow modes, respectively. Nevertheless, the flow mode has advantages such as its reusability, automation, low sample volume (6 µL), and fast response (20 s). Optimization and validation parameters such as enzyme-substrate amount, flow rate, inhibition conditions, repeatability and reproducibility of the biosensor have been performed. The proposed methods have been applied in MT detection in spiked human serum and pharmaceutical dosage forms.

[Enteric parasitic disease in children under 5 years of age, indigenous and non-indigenous, from rural communities in Paraguay]. / Enteroparasitosis en niños bajo 5 años de edad, indígenas y no indígenas, de comunidades rurales del Paraguay.

BACKGROUND: Official figures of mortality in children under five years of age in the Americas, report that infectious and parasitic diseases caused most of the deaths. OBJECTIVE: To evaluate the frequency of intestinal parasites in vulnerable children, indigenous and non-indigenous, and their socio-environmental characteristics. PATIENTS AND METHODS: We evaluated 247 children under five years of age, of both sexes. Descriptive study with an analytical component, transverse cutting. Copro-parasitological examinations were carried out and semi-structured interviews to collect socio-demographic data were conducted. RESULTS: The frequency of intestinal parasitic diseases was 56.1% and 35.5% in indigenous and non-indigenous children, respectively. In both populations, the most common pathogens were Blastocystis hominis and Giardia lamblia. CONCLUSION: We found a high frequency of parasitism in indigenous children at the expense of protozoa. Non-indigenous children still present the same parasitic species found in previous studies, suggesting the need to implement more control and prevention. The poor conditions in which they live favor the development of these diseases.

An iridium oxide nanoparticle and polythionine thin film based platform for sensitive Leishmania DNA detection.

An impedimetric label-free genosensor for high sensitive DNA detection is developed. This system is based on a screen-printed carbon electrode modified with the thionine layer and iridium oxide nanoparticles (IrO2 NP). An aminated oligonucleotide probe is immobilized on the IrO2 NP/polythionine modified electrode and ethanolamine was used as a blocking agent. Different diluted PCR amplified DNA samples have been detected. The selectivity and reproducibility of this system are studied and the system was highly reproducible with RSD ≈ 15% and sensitive enough while using 2% of ethanolamine during the blocking step employed for genosensor preparation.

Use of sibutramine in overweight adult hispanic patients with type 2 diabetes mellitus: a 12-month, randomized, double-blind, placebo-controlled clinical trial.

BACKGROUND: The management of type 2 diabetes mellitus is complicated by the presence of risk factors related to overweight and obesity, particularly visceral adiposity. However, weight loss and weight maintenance are difficult for patients with diabetes, and the benefits of dietary modifications are typically modest. Sibutramine is a serotonin- and norepinephrine-reuptake inhibitor that reduces food intake by inducing early satiety and attenuates the decrease in basal energy expenditure associated with weight loss. Previous trials of sibutramine in overweight and obese patients with type 2 diabetes have shown significant weight loss accompanied by better glycemic control. OBJECTIVE: The goal of this study was to assess the effect on body weight and glycemic control of sibutramine in combination with glibenclamide in obese Hispanic patients with type 2 diabetes. METHODS: This was a 12-month, randomized, double-blind, placebo-controlled clinical trial conducted at the Endocrinology Service, General Hospital of Mexico, Mexico City. Included were overweight or obese (body mass index [BMI] >27 kg/M2) patients with type 2 diabetes between the ages of 24 and 65 years who had been receiving glibenclamide monotherapy for at least 2 weeks and whose glucose concentrations were stable. Patients were randomized to receive sibutramine 10 mg or placebo once daily. The primary efficacy measures were change in body weight, waist circumference, and glycosylated hemoglobin (HbA1c). Anthropometrics and fasting glucose concentrations were measured monthly. HbA1c was determined at baseline and at 6 and 12 months. Laboratory parameters were measured at baseline and at the end of the study. RESULTS: Forty-four patients were randomized to receive sibutramine (28 women, 16 men; mean [SD] age, 47.6 [9.0] years), and 42 were randomized to receive placebo (31 women, 11 men; mean age, 45.8 [8.1] years). Twenty-four patients in the sibutramine group and 23 in the placebo group completed the trial. In the sibutramine group, body weight was reduced from a mean (SD) of 73.9 (10.3) kg at baseline to 69.8 (10.6) kg at month 12; BMI decreased from 29.9 (2.6) to 28.2 (2.9) kg/M2; waist circumference was reduced from 94.9 (8.4) to 90.8 (8.4) cm; the plasma fasting glucose concentration decreased from 140.4 (29.4) to 114.2 (32.0) mg/dL; and the HbA1c value was reduced from 8.9% (1.2) to 8.3% (1.2) (all, P < 0.001). In the placebo group, the corresponding changes were from 74.5 (10.3) kg at baseline to 73.1 (11.2) kg at month 12; from 30.1 (2.5) to 29.5 (2.9) kg/M2; from 94.4 (7.3) to 93.1 (8.3) cm (P < 0.05); from 140.7 (25.2) to 123.9 (38.3) mg/dL (P < 0.05); and from 9.0% (1.2) to 9.1% (1.3). In the sibutramine group, weight loss continued for up to 12 months. CONCLUSION: In this population of obese Hispanic patients with type 2 diabetes, sibutramine combined with glibenclamide therapy achieved weight loss for up to 12 months and was associated with better glycemic control than placebo.