Nanozymes in Point-of-Care Diagnosis: An Emerging Futuristic Approach for Biosensing

Nanomaterial-based artificial enzymes (or nanozymes) have attracted great attention in the past few years owing to their capability not only to mimic functionality but also to overcome the inherent drawbacks of the natural enzymes. Numerous advantages of nanozymes such as diverse enzyme-mimicking activities, low cost, high stability, robustness, unique surface chemistry, and ease of surface tunability and biocompatibility have allowed their integration in a wide range of biosensing applications. Several metal, metal oxide, metal-organic framework-based nanozymes have been exploited for the development of biosensing systems, which present the potential for point-of-care analysis. To highlight recent progress in the field, in this review, more than 260 research articles are discussed systematically with suitable recent examples, elucidating the role of nanozymes to reinforce, miniaturize, and improve the performance of point-of-care diagnostics addressing the ASSURED (affordable, sensitive, specific, user-friendly, rapid and robust, equipment-free and deliverable to the end user) criteria formulated by World Health Organization. The review reveals that many biosensing strategies such as electrochemical, colorimetric, fluorescent, and immunological sensors required to achieve the ASSURED standards can be implemented by using enzyme-mimicking activities of nanomaterials as signal producing components. However, basic system functionality is still lacking. Since the enzyme-mimicking properties of the nanomaterials are dictated by their size, shape, composition, surface charge, surface chemistry as well as external parameters such as pH or temperature, these factors play a crucial role in the design and function of nanozyme-based point-of-care diagnostics. Therefore, it requires a deliberate exertion to integrate various parameters for truly ASSURED solutions to be realized. This review also discusses possible limitations and research gaps to provide readers a brief scenario of the emerging role of nanozymes in state-of-the-art POC diagnosis system development for futuristic biosensing applications.

Antifungal activity and toxicological parameters of 8-hydroxyquinoline-5-sulfonamides using alternative animal models

AIM

The purpose of this study was to evaluate the antifungal activity and toxicological parameters of 8-hydroxyquinoline derivatives PH151 and PH153 using alternative animal models, to understand their behaviour when subjected to in vivo experiments.

METHODS AND RESULTS

We used Toll-deficient Drosophila melanogaster to test the protective effect of compounds against Candida albicans infection. Toxicological parameters were investigated in chicken and zebrafish embryos. PH151 and PH153 showed low toxicity and the treated flies with these compounds had a significantly higher survival rate than untreated flies after 7 days of infection. The compounds did not cause interruption of chicken embryogenesis. Zebrafish embryos exposed to compounds showed dose-dependent toxicity.

CONCLUSIONS

The data supported the potential of PH151 and PH153 for the treatment of systemic candidiasis and demonstrated to be appropriate drug candidates for further studies using mammalian models.

SIGNIFICANCE AND IMPACT OF THE STUDY

The increased incidence of Candida infections resistant to antifungals currently available requires acceleration of the discovery of new agents with properties of inhibiting this fungal pathogen. In this study, we have described the antifungal potential and toxicity of two 8-hydroxyquinoline derivatives using in vivo alternative models, and the results confirm their potential to be developed as new drug candidates.

Acute embryonic exposure of zebrafish to permethrin induces behavioral changes related to anxiety and aggressiveness in adulthood

Permethrin (PM) is one of the most used synthetic pyrethroid worldwide. Exposure to this compound during pregnancy and early childhood has been indicated as a risk factor for neurodevelopmental disorders. We evaluated the long-term effects of embryonic PM exposure in different stages of zebrafish development. Briefly, embryos (3 hpf) were exposed to sub-lethal concentrations of PM (25 and 50 μg.L^-1) during 24 h and then behavioral parameters were evaluated during embryonic (28 hpf), eleutheroembryonic (3 dpf), larval (7 dpf), and adult stages (90 dpf). PM exposure decreased spontaneous movement at 28 hpf and decreased thigmotaxis in eleutheroembryos. The long-term effects of PM include changes in non-motor behaviors such as fear and anxiety in larva and adults. Adults embryonically exposed to PM also showed a significant increase in aggressiveness parameters. These results demonstrated that embryonic exposure to PM induces persistent neurotoxic effects in adulthood, which can impair the cognitive and behavioral fitness of non-target species contributing to a rise in neurodevelopmental disorders.

Data on the phosphorylation of p38MAPK and JNK induced by chlorpyrifos in Drosophila melanogaster

Exposure to organophosphate compounds, such as chlorpyrifos, has been linked to disturbances on cell signaling pathways. Mitogen activated protein kinases (MAPK) are a family of protein kinases involved in a range of cellular processes, including stress response, apoptosis and survival. Therefore, changes in the activation state of these kinases may characterize key mechanisms of toxicity elicited by xenobiotics. Here we report data on the phosphorylation of p38MAPK and JNK, members of the MAPK family, in Drosophila melanogaster exposed to chlorpyrifos, as characterized by western blotting assays.

Oxidative stress markers in fish (Astyanax sp. and Danio rerio) exposed to urban and agricultural effluents in the Brazilian Pampa biome

Aquatic ecosystems are under constant risk due to industrial, agricultural, and urban activities, compromising water quality and preservation of aquatic biota. The assessment of toxicological impacts caused by pollutants to aquatic environment using biomarker measurements in fish can provide reliable data to estimate sublethal effects posed by chemicals in contaminated areas. In this study, fish (Astyanax sp. and Danio rerio) exposed to agricultural and urban effluents at the Vacacaí River, Brazil, were tested for potential signs of aquatic contamination. This river comprehends one of the main watercourses of the Brazilian Pampa, a biome with a large biodiversity that has been neglected in terms of environmental and social-economic development. Sites S1 and S2 were chosen by their proximity to crops and wastewater discharge points, while reference site was located upstream of S1 and S2, in an apparently non-degraded area. Fish muscle and brain tissues were processed for determination of acetylcholinesterase as well as oxidative stress-related biomarkers. The results showed signs of environmental contamination, hallmarked by significant changes in cholinesterase activity, expression of metallothionein, antioxidant enzymes, glutathione levels, and activation of antioxidant/cell stress response signaling pathways in fish exposed to contaminated sites when compared to reference. Based on these results, it is evidenced that urban and agricultural activities are posing risk to the environmental quality of water resources at the studied area. It is also demonstrated that cell stress biomarkers may serve as important tools for biomonitoring and development of risk assessment protocols in the Pampa biome.

Assessment of water pollution in the Brazilian Pampa biome by means of stress biomarkers in tadpoles of the leaf frog Phyllomedusa iheringii (Anura: Hylidae)

The Brazilian Pampa biome is currently under constant threat due to increase of agriculture and improper management of urban effluents. Studies with a focus on the assessment of impacts caused by human activities in this biome are scarce. In the present study, we measured stress-related biomarkers in tadpoles of the leaf frog Phyllomedusa iheringii, an endemic species to the Pampa biome, and tested its suitability as a bioindicator for the assessment of potential aquatic contamination in selected ponds (S1 and S2) nearby agricultural areas in comparison to a reference site. A significant decrease in acetylcholinesterase activity was observed in S2 when compared to S1 and reference. The levels of total-hydroperoxides were increased in S2 site. In parallel, increased activity of the antioxidant enzymes catalase, superoxide dismutase and glutathione S-transferase were observed in S2 when compared to S1 and reference. Further studies are necessary in order to correlate the changes observed here with different chemical stressors in water, as well as to elucidate mechanisms of toxicity induced by pesticides in amphibian species endemic to the Pampa biome. Nevertheless, our study validates Phyllomedusa iheringii as a valuable bioindicator in environmental studies.

Effects of Hg(II) exposure on MAPK phosphorylation and antioxidant system in D. melanogaster

The heavy metal mercury is a known toxin, but while the mechanisms involved in mercury toxicity have been well demonstrated in vertebrates, little is known about toxicological effects of this metal in invertebrates. Here, we present the results of our study investigating the effects associated with exposure of fruit fly Drosophila melanogaster to inorganic mercury (HgCl2 ). We quantify survival and locomotor performance as well as a variety of biochemical parameters including antioxidant status, MAPK phosphorylation and gene expression following mercury treatment. Our results demonstrate that exposure to Hg(II) through diet induced mortality and affected locomotor performance as evaluated by negative geotaxis, in D. melanogaster. We also saw a significant impact on the antioxidant system including an inhibition of acetylcholinesterase (Ache), glutathione S-transferase (GST) and superoxide dismutase (SOD) activities. We found no significant alteration in the levels of mRNA of antioxidant enzymes or NRF-2 transcriptional factor, but did detect a significant up regulation of the HSP83 gene. Mercury exposure also induced the phosphorylation of JNK and ERK, without altering p38(MAPK) and the concentration of these kinases. In parallel, Hg(II) induced PARP cleavage in a 89 kDa fragment, suggesting the triggering of apoptotic cell death in response to the treatment. Taken together, this data clarifies and extends our understanding of the molecular mechanisms mediating Hg(II) toxicity in an invertebrate model.

Guidelines for the use of human immunoglobulin therapy in patients with primary immunodeficiencies in Latin America

Antibodies are an essential component of the adaptative immune response and hold long-term memory of the immunological experiences throughout life. Antibody defects represent approximately half of the well-known primary immunodeficiencies requiring immunoglobulin replacement therapy. In this article, the authors review the current indications and therapeutic protocols in the Latin American environment. Immunoglobulin replacement therapy has been a safe procedure that induces dramatic positive changes in the clinical outcome of patients who carry antibody defects.

Is the lobster cockroach Nauphoeta cinerea a valuable model for evaluating mercury induced oxidative stress?

Organic and inorganic forms of mercury are highly neurotoxic environmental contaminants. The exact mechanisms involved in mercury neurotoxicity are still unclear. Oxidative stress appears to play central role in this process. In this study, we aimed to validate an insect-based model for the investigation of oxidative stress during mercury poisoning of lobster cockroach Nauphoeta cinerea. The advantages of using insects in basic toxicological studies include the easier handling, rapid proliferation/growing and absence of ethical issues, comparing to rodent-based models. Insects received solutions of HgCl2 (10, 20 and 40mgL(-1) in drinking water) for 7d. 24h after mercury exposure, animals were euthanized and head tissue samples were prepared for oxidative stress related biochemical determinations. Mercury exposure caused a concentration dependent decrease in survival rate. Cholinesterase activity was unchanged. Catalase activity was substantially impaired after mercury treatment 40mgL(-1). Likewise, GST had a significant decrease, comparing to control. Peroxidase and thioredoxin reductase activity was inhibited at concentrations of 20mgL(-1) and 40mgL(-1) comparing to control. These results were accompanied by decreased GSH levels and increased hydroperoxide and TBARS formation. In conclusion, our results show that mercuric compounds are able to induce oxidative stress signs in insect by modulating survival rate as well as inducing impairments on important antioxidant systems. In addition, our data demonstrates for the first time that Nauphoeta cinerea represents an interesting animal model to investigate mercury toxicity and indicates that the GSH and thioredoxin antioxidant systems plays central role in Hg induced toxicity in insects.

Critical issues and needs in management of primary immunodeficiency diseases in Latin America

Experts from six Latin American countries met to discuss critical issues and needs in the diagnosis and management of primary immunodeficiency diseases (PIDD). The diagnosis of PIDD is generally made following referral to an immunology centre located in a major city, but many paediatricians and general practitioners are not sufficiently trained to suspect PIDD in the first place. Access to laboratory testing is generally limited, and only some screening tests are typically covered by government health programmes. Specialised diagnostic tests are generally not reimbursed. Access to treatment varies by country reflecting differences in healthcare systems and reimbursement policies. An online PIDD Registry Programme for Latin America has been available since 2009, which will provide information about PIDD epidemiology in the region. Additional collaboration across countries appears feasible in at least two areas: a laboratory network to facilitate the diagnosis of PIDD, and educational programmes to improve PIDD awareness. In total, these collaborations should make it possible to advance the diagnosis and management of PIDD in Latin America.

Immunodeficiencies

Primary immunodeficiencies (PIDs) are uncommon, chronic and severe disorders of the immune system in which patients cannot mount a sufficiently protective immune response, leading to an increased susceptibility to infections. The treatment of choice for PID patients with predominant antibody deficiency is intravenous immunoglobulin (Ig) replacement therapy. Despite major advances over the last 20 years in the molecular characterization of PIDs, many patients remain undiagnosed or are diagnosed too late, with severe consequences. Various strategies to ensure timely diagnosis of PIDs are in place, and novel approaches are being developed. In recent years, several patient registries have been established. Such registries shed light on the pathology and natural history of these varied disorders. Analyses of the registry data may also reveal which patients are likely to respond well to higher Ig infusion rates and may help to determine the optimal dosing of Ig products. Faster infusion rates may lead to improved convenience for patients and thus increase patient compliance, and may reduce nursing time and the need for hospital resources. Data from two recent studies suggest that Gamunex and Privigen are well tolerated at high infusion rates. Nevertheless, careful selection of patients for high infusion rates, based on co-morbid conditions and tolerance of the current infusion rate, is advisable. Based on the available data, intravenous Ig offers broad protection against encapsulated organisms. As vaccine trends change, careful monitoring of specific antibody levels in the general population, such as those against pneumococcal and meningococcal bacteria, should be implemented.

Endemically exposed asymptomatic individuals show no increase in the specific Leishmania (Viannia) panamensis-Th1 immune response in comparison to patients with localized cutaneous leishmaniasis

In Colombia, most cases of human cutaneous leishmaniasis are caused by Leishmania (Viannia) panamensis. Interestingly, up to 30% of the exposed population do not suffer from clinical leishmaniasis although it is likely that they are continuously infected with Leishmania parasites. Since it is believed that the induction of efficient Th1 immune responses protects against Leishmania infections both in humans and in animal models, we determined if endemically exposed asymptomatics showed stronger Leishmania-specific Th1 immune responses than patients with active localized cutaneous leishmaniasis (LCL). We found that Montenegro skin test responses were slightly higher among asymptomatic individuals compared to patients suffering from LCL. However, PBMC from patients with LCL showed similar Leishmania-specific proliferative responses compared to PBMC from asymptomatic individuals. Furthermore, PBMC from both groups also secreted similar amounts of IFN-gamma, IL-12p40 and IL-10 after in vitro exposure to L. panamensis. No IL-4 was detected in the supernatants. Taken together our results suggest that lack of LCL development in endemically exposed asymptomatics cannot be explained by stronger systemic anti-Leishmania Th1 immune responses or decreased Th2 responses in these individuals in comparison to individuals who develop LCL. It may be possible that other mechanisms are responsible for resistance to cutaneous leishmaniasis in Colombia in endemically exposed asymptomatics.

Mandibular reconstruction with the free vascularized fibular flap: utility of three-dimensional computerized tomography

Oncologic management in the mandibular area leaves important osseous defects, that require reconstructive procedures with vascularized osseous tissues. Mandibular reconstructions with free vascularized fibular flaps have well-defined indications and some advantages over various other types of vascularized osseous grafts, because the fibular graft permits the reconstruction of large mandibular defects. This study demonstrates the usefulness of three-dimensional (3D) tomography as a tool to determine the size of the defect, and with angiotomography, to define the anatomic pattern of the vascular pedicle. Five patients with varying mandibular tumors and osseous defects were evaluated with 3D tomography in the pre- and postoperative periods. Two patients were immediately reconstructed with vascularized fibular flaps. 3D preoperative tomography showed the dimensions of the tumor, the dimensions of the mandibular resection, and the graft vascular pattern. Three patients were secondarily reconstructed, two of them with partial mandibular defects, and one patient with total mandibular reconstruction. In the preoperative period, 3D tomography was used to determine the dimensions of the mandibular defect, as well as the area of the osteotomies. The technology permits an exact knowledge of the dimension of mandibular defects, allowing better planning of reconstructive procedures.

Quantitative and cell-cycle differences in progenitor cells mobilized by recombinant human interleukin-7 and recombinant human granulocyte colony-stimulating factor

Administration of recombinant human interleukin-7 (rhIL-7) to mice increases the exportation of myeloid progenitors (colony-forming unit [CFU]-c and CFU-granulocyte erythroid megakaryocyte macrophage [CFU-GEMM]) from the bone marrow (BM) to peripheral organs, including blood, and also increases the number of primitive progenitor and stem cells in the peripheral blood (PB). We now report that combined treatment of mice with rhIL-7 and recombinant human granulocyte-colony stimulating factor (rhG-CSF) stimulates a twofold to 10-fold increase in the total number of PB CFU-c, and a twofold to fivefold increase in the total number of PB CFU-spleen at day 8 (CFU-S8) over the increase stimulated by rhIL-7 or rhG-CSF alone. In addition, the quality of mobilized cells with trilineage, long-term marrow-repopulating activity is maintained or increased in mice treated with rhIL-7 and rhG-CSF compared with rhIL-7 or rhG-CSF alone. These differences in mobilizing efficiency suggest qualitative differences in the mechanisms by which rhIL-7 and rhG-CSF mobilize progenitor cells, in fact, the functional status of progenitor cells mobilized by rhIL-7 differs from that of cells mobilized by rhG-CSF in that the incidence of actively cycling (S-phase) progenitors obtained from the PB is about 20-fold higher for rhIL-7-treated mice than for mice treated with rhG-CSF. These results suggest the use of rhIL-7-mobilized progenitor/stem cells for gene-modification and tracking studies, and highlight different functions and rates of repopulation after reconstitution with PB leukocytes obtained from mice treated with rhIL-7 versus rhG-CSF.

Administration of interleukin 12 with pulse interleukin 2 and the rapid and complete eradication of murine renal carcinoma

BACKGROUND

Interleukin 2 (IL-2) and interleukin 12 (IL-12) are potent immunoregulatory cytokines that exhibit antitumor activity. Preliminary evidence suggests that combined administration of IL-2 and IL-12 may yield greater antitumor activity than that observed with either agent alone.

PURPOSE

We evaluated the ability of combination regimens of IL-2 and IL-12 to induce regression of established primary and metastatic murine renal carcinoma (Renca) tumors.

METHODS

BALB/c mice were given either subcutaneous or intrarenal injections of 10(5) Renca cells; tumor cell injections were given to 10-12 mice for each treatment group. Mice bearing subcutaneous primary tumors were treated with chronic IL-2 (300,000 IU given on a daily basis) or pulse IL-2 (300,000 IU given twice daily one day per week) alone, IL-12 alone (0.5 micrograms given on a daily basis), or IL-12 in combination with either chronic or pulse IL-2. Mice with metastatic tumors (arising from intrarenal implants; animals were nephrectomized to remove the primary tumors) were treated with IL-12 plus or minus pulse IL-2; in these experiments, IL-12 was given at doses of either 0.5 or 1.0 micrograms. In most experiments, treatment was continued for at least 3 weeks. Two-sided statistical tests were used to evaluate the data.

RESULTS

Most mice with subcutaneous Renca tumors treated with the combination of IL-12 and chronic IL-2 died of treatment-related toxic effects within 7-14 days. In contrast, treatment with IL-12 plus pulse IL-2 was well tolerated, and six of 10 mice experienced complete tumor regression; none of the mice treated with either IL-12 alone or pulse Il-2 alone experienced a curative response. Seven of eight and nine of nine mice with metastatic tumors experienced complete tumor regression after treatment with 0.5 micrograms IL-12 plus pulse IL-2 or 1.0 microgram IL-12 plus pulse IL-2, respectively; two of 12 mice treated with pulse IL-2 alone and 10% or less of mice treated with IL-12 alone were cured of metastatic tumors (with 0.5 micrograms IL-12, none of 10 mice; with 1.0 micrograms IL-12, one of 10 mice). Five of 10 mice with metastatic tumors treated with a short-course regimen of IL-12 and pulse IL-2 (two pulses of IL-2 flanking 5 days of 0.5 micrograms IL-12) experienced complete tumor regression, while only one of the 12 mice treated with IL-2 alone and none of the mice treated with IL-12 alone experienced complete tumor regression. Virtually all curative response frequencies obtained with IL-12 and pulse IL-2 combination regimens differed significantly (P < .05) from those obtained with corresponding single-agent treatments.

CONCLUSIONS

IL-12 administered in combination with pulse IL-2 induced rapid and complete regression of primary and metastatic Renca tumors and displayed greater antitumor activity than that observed with either IL-12 or IL-2 alone.

Partial degradation of T-cell signal transduction molecules by contaminating granulocytes during protein extraction of splenic T cells from tumor-bearing mice

Flavone-8-acetic acid plus recombinant human interleukin 2 is a successful antitumor therapy in mice bearing the Renca murine renal cell carcinoma. This report demonstrates that T cells, particularly CD8+ T cells, are critical for the generation of this response. Initial experiments examining T-cell signal transduction proteins demonstrated that T cells from Renca-bearing mice had undetectable levels of p56lck and zeta-chain of the T-cell receptor and that flavone-8-acetic acid and recombinant human interleukin 2 therapy could be used as a model for reversal of these alterations. However, further experimentation showed that the majority of the reduction in zeta-chain and part of the reduction in p56lck was due to degradation of these molecules during protein extraction caused by mature granulocytes contaminating the enriched T-cell population. This was not the case for nuclear c-Rel or NF kappa B p65, which remained at undetectable/reduced levels in the absence of granulocytes, confirming our previous data that transcription factor alterations exist in tumor-bearing mice. Thus, most of the reduction in zeta-chain in T cells from Renca-bearing mice is due to granulocyte contamination and emphasizes the need to use pure T-cell populations and/or sufficient amounts and types of protease inhibitors when quantitating proteins in T cells from tumor-bearing mice.

Alterations in NF kappa B/Rel family proteins in splenic T-cells from tumor-bearing mice and reversal following therapy

It has recently been shown that T-cell signal transduction molecules are altered in tumor-bearing mice. We have examined the expression of NF kappa B/Rel family proteins in T-cells from mice bearing Renca, a murine renal carcinoma. T-cells from Renca-bearing mice expressed undetectable levels of nuclear c-Rel, NF kappa B p65, and p50; however, two shorter forms of p50 (p48 and p46), truncated at the NH2-terminus, were present exclusively in the nucleus and were able to bind DNA. These T-cells have reduced expression of gamma-interferon mRNA. In mice successfully treated with flavone 8-acetic acid and recombinant human interleukin 2, the T-cells expressed normal levels of all three nuclear NF kappa B/Rel proteins. These results suggest that alterations in transcription factors may accompany changes in signal transduction molecules in T-cells from tumor-bearing animals; however, the changes are reversed with successful biological therapy.