Presence Of Human Blood Research Articles

Microfiber Fragment Pollution: Sources, Toxicity, Strategies, and Technologies for Remediation

With the pervasive consumption (currently >65% of total market shares and steadily increasing) of petroleum-derived synthetic textiles, the escalating concern of microfiber fragment (MF) pollution has emerged as a formidable menace to our ecological equilibrium. Over the lifetime (pre- and post-consumption) of these textiles, they shed tiny fibers recognized as MFs. These MFs are carriers of persistent organic pollutants and have been linked to cytotoxicity, oxidative stress, and genotoxicity, even at minimal exposures via air and water sources. Grounded in the state-of-the-art literature, this review discusses the primary and secondary sources of MF release, their fate, transport, environmental impacts, and novel technologies for MF pollutant remediation. Our results infer that MF pollution is a multifactorial issue with serious environmental and public health implications, as studies reported their presence in human blood, feces, and urine samples. We recommend a multifaceted approach to increase sanitation coverage, ensuring adequate wastewater treatment prior to environmental discharge for MF pollution mitigation. Additionally, transformation is warranted for consumers’ use, care, and purchase behavior of textile products. Government regulation of fast fashion (a major user of synthetic textiles), exemplified by recent French legislation, is essential to preventing microfiber pollution. We urge similar policy-making efforts globally to safeguard public health.

Using a human colonoid-derived monolayer to study bacteriophage translocation

ABSTRACT Bacteriophages (phages) are estimated to be the most abundant microorganisms on Earth. Their presence in human blood suggests that they can translocate from non-sterile sites such as the gastrointestinal tract where they are concentrated. To examine phage translocation ex vivo, we adapted a primary colonoid monolayer model possessing cell diversity and architecture, and a thick layer of mucus akin to the colonic environment in vivo. We show that the colonoid monolayer is superior to the Caco-2 cell-line model, possessing intact and organized tight junctions and generating a physiologically relevant mucus layer. We showed, using two different phages, that translocation across the colonoid monolayer was largely absent in differentiated monolayers that express mucus, unlike Caco-2 cultures that expressed little to no mucus. By stimulating mucus production or removing mucus, we further demonstrated the importance of colonic mucus in preventing phage translocation. Finally, we used etiological drivers of gut permeability (alcohol, fat, and inflammatory cytokines) to measure their effects on phage translocation, demonstrating that all three stimuli have the capacity to amplify phage translocation. These findings suggest that phage translocation does occur in vivo but may be largely dependent on colonic mucus, an important insight to consider in future phage applications.

#6225 MICROPLASTICS: FIRST EXTENDED PROTEOMIC ANALYSIS ON KIDNEY TUBULAR CELLS

Abstract Background and Aims Several studies have shown the ubiquitous presence of microplastics (plastic fragments between 5 mm and 1 μm in diameter) and nanoplastics (<1 μm) in the environment and their toxicity. Furthermore, microplastics (MPs) absorb a lot of environmental pollutants, such as bisphenol A (BPA), and release them into tissues increasing their toxicity; this is the so called “Trojan Horse” effect. Recent studies have also proved their presence in human blood and human tissues of healthy people, such as placenta and lung, and in cirrhotic liver. Most frequent biological effects of MPs are inflammation, oxidative stress and alteration of metabolic pathways. In this study proteomic analysis was performed to evaluate the toxicity of polyethylene (PE) and bisphenol-A (BPA) MPs on renal tubular cells (HK2) in vitro. This is the first extended proteomic study on human cells. Method HK-2 cultures were exposed for 5-24-48 hours to BPA, PE Microspheres (PE-MP) and MP combined with BPA. Then it was performed a proteomic analysis by mass spectrometry (MS). MS data were obtain by Orbitrap Fusion Tribrid mass spectrometer (ThermoScientific). Analysis of data were performed using unsupervised hierarchical clustering using multidimensional scaling, non-linear support vector machine (SVM) learning, and partial least squares discriminant analysis. In SVM learning, a fourfold cross-validation approach was applied to estimate the prediction and classification accuracy. Results The proteomic analysis showed a clear differentiation of the HK2 proteome based on conditioning and identified a “core” of proteins, significant at ANOVA and above the 95th percentile for “fold increase” and significant at T-test compared with controls, highly discriminatory between groups. Finally, among these, a final set of 6 proteins was selected to be validated for distinguishing features: Nephronectin, GDF15, Vasorin, IGFBP7, Midkine, Tissue factor-F3. Nephronectin is a structural membrane's protein involved in cellular adhesion. GDF15, tissue factor F3 and midkine are markers of stress conditions, including inflammation and oxidative stress. IGFBP7 is a biomarker of acute kidney damage. Vasorin is a transmembrane glycoprotein that protects against apoptosis and fibrosis. Conclusion MP and BPA significantly modify the protein expression in renal tubular cells. These findings highlight the urgent need for additional research into the toxic effects of plastic debris on human kidneys and the eventual link to kidney diseases.

Perfluoroalkyl Substance Serum Concentrations and Cholesterol Absorption-Inhibiting Medication Ezetimibe.

Per- and polyfluoroalkyl substances (PFAS) are human-made compounds with a widespread presence in human blood and other organs. PFAS have been associated with multiple health effects, including higher serum cholesterol and LDL cholesterol. Potential population differences in serum PFAS attributable to ezetimibe, a medication that inhibits cholesterol absorption, are of interest for several reasons. The "C8" Health Project survey data from six contaminated water districts in the mid-Ohio Valley of the United States provide a wide enough range of serum PFAS and a sufficient number of ezetimibe takers to explore this topic. A total of 44,126 adult participants of the C8 Health Survey were included in the community-based study. The status of taking (1075) or non-taking of ezetimibe, alone or in combination with another lipid-lowering agent, was acquired. The geometric mean serum concentrations of the four most commonly detected serum PFAS were compared based on the status of ezetimibe use. There is no significant difference in serum concentrations of perfluorohexanesulfonic acid (PFHxS), perfluorooctanoic acid (PFOA), perfluorooctanesulfonic acid (PFOS), and perfluorononanoic acid (PFNA) between ezetimibe users and non-users after adjustment for age, sex, body mass index, estimated glomerular filtration rate (eGFR), cigarette smoking, education, and average household income. The sterol absorption-inhibiting medication ezetimibe does not appear to affect serum PFAS concentrations. We sought but did not find direct evidence that ezetimibe could inhibit PFAS uptake nor inferential evidence that inter-individual differences in sterol absorption could provide a confounding factor explanation for the association of serum total- and LDL-cholesterol with serum PFAS.

Propagation of S. aureus Phage K in Presence of Human Blood

The specter of antimicrobial resistance has been present as far back as antibiotic treatment for bacterial infections has been available [1].

Tricore photonic crystal fibre based refractive index sensor for glucose detection

An enhanced compact sensitivity of glucose sensor in the presence of human blood using tricore photonic crystal fibre is numerically proposed where one hollow channel filled by analyte acts as liquid core and remain two cores considering the silica substrate. The uniqueness of this structure is single material substrate and capable of tuning its sensitivity with minimum variation of glucose concentration (g/l) to detect the low level presence of glucose in the human blood. The transmission spectrum shows the maximum wavelength shift for x -polarisation at 470 nm, and 440 nm for y -polarisation to the response of refractive index of glucose resulting enhanced average sensitivity of 23,267.33 nm/RIU achieved at 470 nm of wavelength shift. The entire analysis and its mechanism of the proposed structure are applied with help of finite-element method.

Enterococcus faeciumTIR-Domain Genes Are Part of a Gene Cluster Which Promotes Bacterial Survival in Blood

Enterococcus faecium has undergone a transition to a multidrug-resistant nosocomial pathogen. The population structure of E. faecium is characterized by a sharp distinction of clades, where the hospital-adapted lineage is primarily responsible for bacteremia. So far, factors that were identified in hospital-adapted strains and that promoted pathogenesis of nosocomial E. faecium mainly play a role in adherence and biofilm production, while less is known about factors contributing to survival in blood. This study identified a gene cluster, which includes genes encoding bacterial Toll/interleukin-1 receptor- (TIR-) domain-containing proteins (TirEs). The cluster was found to be unique to nosocomial strains and to be located on a putative mobile genetic element of phage origin. The three genes within the cluster appeared to be expressed as an operon. Expression was detected in bacterial culture media and in the presence of human blood. TirEs are released into the bacterial supernatant, and TirE2 is associated with membrane vesicles. Furthermore, the tirE-gene cluster promotes bacterial proliferation in human blood, indicating that TirE may contribute to the pathogenesis of bacteremia.

Thrombogenicity assessment of Pipeline Flex, Pipeline Shield, and FRED flow diverters in an in vitro human blood physiological flow loop model.

Endovascular treatment of intracranial aneurysms with endoluminal flow diverters (single or multiple) has proven to be clinically safe and effective, but is associated with a risk of thromboembolic complications. Recently, a novel biomimetic surface modification with covalently bound phosphorylcholine (Shield Technology™) has shown to reduce the material thrombogenicity of the Pipeline flow diverter. Thrombogenicity of Pipeline Flex, Pipeline Shield, and Flow Redirection Endoluminal Device (FRED) in the presence of human blood under physiological flow conditions—in addition to relative increase in thrombogenicity with multiple devices—remains unknown and was investigated here. Thrombin generation (mean ± SD; μg/mL; thrombin–antithrombin complex or TAT) was measured as FRED (30.3 ± 2.9), Pipeline (13.9 ± 4.4), Pipeline Shield (0.4 ± 0.3), and negative control (no device; 0.1 ± 0.0). Platelet activation (mean ± SD; IU/μL; beta‐thromboglobulin or βTG) was measured as FRED (148 ± 45), Pipeline (92.8 ± 41), Pipeline Shield (16.2 ± 3.5), and negative control (2.70 ± 0.16). FRED was significantly more thrombogenic than Pipeline and Pipeline Shield (p < 0.05) for TAT. Additionally, Pipeline Shield had significantly lower TAT and βTG than the other devices tested (p < 0.05) and these were comparable to the negative control (p > 0.05). TAT and βTG scaled proportionately with multiple Pipeline devices (N = 6) but was unaffected by multiple Pipeline Shield (N = 6) devices—the latter being statistically similar to negative control (p > 0.05). © 2018 The Authors. Journal Of Biomedical Materials Research Part A Published By Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 3195–3202, 2018.

Differential behaviour of endophilic &lt;i&gt;Anopheles&lt;/i&gt; mosquitoes in rooms occupied by tobacco smokers and non-smokers in two Nigerian villages

The behavioural effect of tobacco smoke on endophilic Anopheles mosquitoes was observed in two North Central Nigerian villages. Pyrethrum spray and exit trap collections of mosquitoes were conducted, between April and November 2014, in two different villages where tobacco smoking was common among the residents. Anopheles mosquito samples collected were identified to sibling species level using species-specific polymerase chain reaction. Presence of human blood in the blood-fed mosquitoes was determined by Enzyme-linked immunosorbent assay. Numbers of mosquitoes collected from the rooms inhabited by tobacco smokers and non-smokers were compared using Student’s t-test (p&lt;0.05). At least four times higher exit rates, five times less gravid females and significantly lower numbers of An. gambiae s.l mosquitoes were found in rooms inhabited by tobacco smokers compared to equal sized rooms occupied by non-smokers in each village. Blood feeding rates (77-88%) and human blood indices (0.82-0.87) of mosquitoes were generally high in the habitations of both tobacco smokers and non-smokers. There was predominance of An. gambiae (≥ 86%) species compared to An. coluzzii (≤ 14%) in both villages. Reduced mosquito endophily was observed in the habitations of tobacco smokers compared to the non-smokers. Widespread tobacco smoking habits should be investigated for possible contributions to mosquito behavioural resistance and residual malaria parasite transmission within rural communities.Keywords: Anopheles mosquitoes, Tobacco Smoke, Exophily, Malaria

Biosensing estrogenic endocrine disruptors in human blood and urine: A RAPID cell-free protein synthesis approach

Many diseases and disorders are linked to exposure to endocrine disrupting chemicals (EDCs) that mimic the function of natural estrogen hormones. Here we present a Rapid Adaptable Portable In-vitro Detection biosensor platform (RAPID) for detecting chemicals that interact with the human estrogen receptor β (hERβ). This biosensor consists of an allosteric fusion protein, which is expressed using cell-free protein synthesis technology and is directly assayed by a colorimetric response. The resultant biosensor successfully detected known EDCs of hERβ (BPA, E2, and DPN) at similar or better detection range than an analogous cell-based biosensor, but in a fraction of time. We also engineered cell-free protein synthesis reactions with RNAse inhibitors to increase production yields in the presence of human blood and urine. The RAPID biosensor successfully detects EDCs in these human samples in the presence of RNAse inhibitors. Engineered cell-free protein synthesis facilitates the use of protein biosensors in complex sample matrices without cumbersome protein purification.

In Vitro Testing of Crude Natural Plant Extracts from Costa Rica for Their Ability to Boost Innate Immune Cells against Staphylococcus aureus.

The increasing occurrence of antibiotic-resistant Staphylococcus (S.) aureus tremendously limits the antibiotic-based treatment options; therefore, an open discussion of alternative treatment strategies is urgently needed. The use of naturally derived materials might become a more promising concept, not only as directly acting antimicrobials, but also for stimulation of the immune system. Costa Rican plant extracts were screened for their ability to enhance the antimicrobial activity of human blood-derived cells against S. aureus infections. We identified three plant extracts which significantly reduced the growth of S. aureus in the presence of human blood without directly acting as antibacterials: Byrsonima crassifolia acetone bark extract, Mandevilla veraguasensis acetone vine extract and Verbesina oerstediana acetone bark extract (VEOEBA). The effect of VEOEBA was studied in more detail, and revealed that VEOEBA increases the antimicrobial activity of neutrophils by enhancing the formation of neutrophil extracellular traps.

Determination of the foraging behaviour and blood meal source of malaria vector mosquitoes in Trincomalee District of Sri Lanka using a multiplex real time polymerase chain reaction assay.

BackgroundStudies of host preference patterns in blood-feeding anopheline mosquitoes are crucial to incriminating malaria vectors. However, little information is available on host preferences of Anopheles mosquitoes in Sri Lanka.MethodsAdult Anopheles mosquitoes were collected from five selected sentinel sites in Trincomalee District during June–September 2011. Each blood-fed mosquito was processed on filter papers. DNA was extracted using the dried blood meal protocol of the QIAmp DNA mini kit. A multiplexed, real-time PCR assay targeting eight animals was developed for two panels to identify the host meal of Anopheles. Human blood index (HBI), forage ratio (FR) and host feeding index (HFI) were calculated.ResultsA total of 280 field-caught, freshly engorged female mosquitoes belonging to 12 anopheline species were analysed. The overall HBI and HFI in the present study were low indicating that humans were not the preferred host for the tested anopheline species. Nevertheless, a small proportion engorged Anopheles aconitus, Anopheles culicifacies, Anopheles barbirostris, Anopheles annularis, Anopheles subpictus, Anopheles peditaeniatus, Anopheles pseudojamesi, and Anopheles barbumbrosus contained human blood.ConclusionThe presence of human blood in mosquito species indicates the possibility of them transmitting malaria. Further studies on vector competence are needed to determine the role of each of the above anopheline species as efficient vectors of malaria.

An Evaluation of Setting Time of Mineral Trioxide Aggregate and EndoSequence Root Repair Material in the Presence of Human Blood and Minimal Essential Media

IntroductionThe purpose of this study was to compare the ability of MTA (Dentsply Maillefer, Tulsa, OK) and EndoSequence Root Repair Material (ESRRM; Brasseler USA, Savannah, GA) to set in the presence of human blood and minimal essential media. MethodsA model was created using polymethyl methacrylate blocks each prepared with 10 standardized wells (2-mm diameter × 3-mm depth). Prepared ProRoot MTA (Dentsply Maillefer) and ESRRM were each placed in 6 separate blocks. The samples were distributed among the 4 different media (ie, blood, minimal essential media, blood and minimal essential media, and sterile saline as the control). Each block was submerged for 4, 5, 6, 8, 24, 36, and 48 hours in an incubator at 37°C with 100% humidity. ResultsThe results revealed that regardless of the type of media exposure, neither of the materials set at 4 or 6 hours. ESRRM was not set at 48 hours, whereas all of the MTA samples were set at 36 hours. ConclusionsThis outcome draws into question the proposed setting time given by each respective manufacturer. Furthermore, despite ESRRM being marketed as a direct competitor to MTA with superior handling properties, MTA consistently set at a faster rate under the conditions of this study.

A Protein Transduction Domain with Cell Uptake and Selectivity Profiles that Are Controlled by Multivalency Effects

Protein transduction domains (PTDs) are reagents that facilitate the delivery of diverse cargo to the interior of mammalian cells. We identified a PTD called "Ypep" (N-YTFGLKTSFNVQ-C), with cell penetration selectivity and potency profiles that are tightly controlled by multivalency effects. Pentavalent display of Ypep on M13 bacteriophage enables selective uptake of this phage in PC-3 human prostate cancer cells at low picomolar concentrationand in the presence of human blood. All Ypep-dependent delivery is nontoxic and proceeds through energy-dependent endocytosis. Collectively, our results establish Ypep-displaying phage as a cell-penetrating platform with selectivity and potency profiles that compare to, or exceed, antibodies and their fragments. Our findings may have broader implications on the design of PTD technologies generated from phage display, as well as the use of Ypep-displaying phage as a prostate cancer cell-selective delivery platform.

Male reproductive system parameters in a two-generation reproduction study of ammonium perfluorooctanoate in rats and human relevance

Ammonium perfluorooctanoate (ammonium PFOA) is an industrial surfactant that has been used primarily as a processing aid in the manufacture of fluoropolymers. The environmental and metabolic stability of PFOA together with its presence in human blood and long elimination half-life have led to extensive toxicological studies in laboratory animals. Two recent publications based on observations from the Danish general population have reported: (1) a negative association between serum concentrations of PFOA in young adult males and their sperm counts and (2) a positive association among women with time to pregnancy. A two-generation reproduction study in rats was previously published (2004) in which no effects on functional reproduction were observed at doses up to 30 mg ammonium PFOA/kg body weight. The article contained the simple statement: “In males, fertility was normal as were all sperm parameters”. In order to place the recent human epidemiological data in perspective, herein we provide the detailed male reproductive parameters from that study, including sperm quality and testicular histopathology. Sperm parameters in rats from the two-generation study in all ammonium PFOA treatment groups were unaffected by treatment with ammonium PFOA. These observations reflected the normal fertility observations in these males. No evidence of altered testicular and sperm structure and function was observed in ammonium PFOA-treated rats whose mean group serum PFOA concentrations ranged up to approximately 50,000 ng/mL. Given that median serum PFOA in the Danish cohorts was approximately 5 ng/mL, it seems unlikely that concentrations observed in the general population, including those recently reported in Danish general population, could be associated causally with a real decrement in sperm number and quality.

Development and Characterization of Chitosan-Based Polymeric Hydrogel Membranes

The current study deals with the development of a glutaraldehyde cross-linked chitosan-based delivery system with improved mechanical properties utilizing the reactive solvent technique. The prepared systems were characterized by Fourier Transform Infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The systems were also analysed for mechanical and pH-dependent swelling properties and they were also analysed for their haemocompatibility and cytocompatibility. FT-IR studies indicated formation of imine bonds during the cross-linking reaction of chitosan and glutaraldehyde. TGA, XRD and mechanical studies indicated optimal properties for the system prepared with 5% methacrylic acid as reactive solvent. The developed systems indicated pH-dependent swelling behaviour with increased swelling at lower pH. The prepared delivery systems were found to be highly haemocompatible in the presence of human blood and cytocompatible in the presence of L929 fibroblast cells. The release of the model drug (salicylic acid) from the delivery systems in 0.01 M HCl indicated Fickian kinetics. The developed delivery systems could be used to deliver drugs selectively in the stomach.

Pharmacokinetic modeling of perfluorooctanoic acid during gestation and lactation in the mouse

Perfluorooctanoic acid (PFOA) is a processing aid for the polymerization of commercially valuable fluoropolymers. Its widespread environmental distribution, presence in human blood, and adverse effects in animal toxicity studies have triggered attention to its potential adverse effects to humans. PFOA is not metabolized and exhibits dramatically different serum/plasma half-lives across species. Estimated half-lives for humans, monkeys, mice, and female rats are 3–5 years, 20–30 days, 12–20 days, and 2–4h, respectively. Developmental toxicity is one of the most sensitive adverse effects associated with PFOA exposure in rodents, but its interpretation for risk assessment is currently hampered by the lack of understanding of the inter-species pharmacokinetics of PFOA. To address this uncertainty, a biologically supported dynamic model was developed whereby a two-compartment system linked via placental blood flow described gestation and milk production linked a lactating dam to a growing pup litter compartment. Postnatal serum levels of PFOA for 129S1/SvImJ mice at doses of 1mg/kg or less were reasonably simulated while prenatal and postnatal measurements for CD-1 mice at doses of 1mg/kg or greater were simulated via the addition of a biologically based saturable renal resorption description. Our results suggest that at low doses a linear model may suffice for describing the pharmacokinetics of PFOA while a more complex model may be needed at higher doses. Although mice may appear more sensitive based on administered dose of PFOA, the internal dose metrics estimated in this analysis indicate that they may be equal or less sensitive than rats.

Induction of leptin resistance through direct interaction of C-reactive protein with leptin

The mechanisms underlying leptin resistance are still being defined. We report here the presence in human blood of several serum leptin-interacting proteins (SLIPs), isolated by leptin-affinity chromatography and identified by mass spectrometry and immunochemical analysis. We confirmed that one of the major SLIPs is C-reactive protein (CRP). In vitro, human CRP directly inhibits the binding of leptin to its receptors and blocks its ability to signal in cultured cells. In vivo, infusion of human CRP into ob/ob mice blocked the effects of leptin upon satiety and weight reduction. In mice that express a transgene encoding human CRP, the actions of human leptin were completely blunted. We also found that physiological concentrations of leptin can stimulate expression of CRP in human primary hepatocytes. Recently, human CRP has been correlated with increased adiposity and plasma leptin. Thus, our results suggest a potential mechanism contributing to leptin resistance, by which circulating CRP binds to leptin and attenuates its physiological functions.

Human airway and peripheral blood eosinophils enhance Th1 and Th2 cytokine secretion

The effector function of eosinophils involves their release of toxic granule proteins, reactive oxygen species, cytokines, and lipid mediators. Murine studies have demonstrated that eosinophils can also enhance T cell function. Whether human eosinophils, in particular, airway eosinophils, have similar immunoregulatory activity has not been fully investigated. The aim of this study was to determine whether human blood and airway eosinophils can contribute to Th1 and Th2 cytokine generation from CD4+ T cells stimulated with superantigen. Eosinophils were obtained from blood or bronchoalveolar lavage fluid 48 h after segmental allergen bronchoprovocation. Purified eosinophils were co-cultured with autologous CD4+ blood T cells in the presence of staphylococcal enterotoxin B (SEB). Cytokine levels in the supernatant fluid were determined by enzyme-linked immunosorbent assay (ELISA). Eosinophil expression of major histocompatibility complex (MHC) class II and co-stimulatory molecules was assessed by flow cytometry before culture, 24 h after granulocyte-macrophage colony-stimulating factor (GM-CSF) stimulation, and 24 h after co-culture with CD4+ T cells and SEB. Interleukin (IL)-5, IL-13, and interferon (IFN)-gamma generation increased when CD4+ T cells were co-cultured with either blood or airway eosinophils in the presence of SEB. The ability of eosinophils to enhance cytokine generation was independent of their source (blood vs airway), activation by GM-CSF, or detectable expression of human leukocyte antigen (HLA)-DR, CD80, or CD86. Our data demonstrate that SEB-induced generation of Th1 and Th2 cytokines is increased in the presence of human blood and airway eosinophils. Thus, eosinophils can have an immunoregulatory function in pathogen-associated allergic diseases such as atopic dermatitis, chronic sinusitis, and asthma exacerbations.

NUCLEOSIDE PRODRUGS OF A3 ADENOSINE RECEPTOR AGONISTS AND ANTAGONISTS.

9-(β-D-Ribosfuranosyluronamide)adenine derivatives that are selective agonists and antagonists of the A3 adenosine receptor (AR) have been derivatized as prodrugs for in vivo delivery. The free hydroxy groups at the 2' and 3' positions of the agonists 2-chloro-N 6-(3-iodobenzyl)-9-(N-methyl-(β-D-ribosfuranosyluronamide)adenine 2b, the corresponding 4'-thio nucleoside 2c, and antagonists 4a and 4b (5'-N,N-dimethylamides related to 2b and 2c, respectively) were derivatized through simple acylation reactions. The prodrug derivatives were tested in radioligand binding assays at ARs and in a functional assay of adenylate cyclase at the A3AR and found to be considerably less active than the parent drugs. The hydrolysis of nucleoside 2',3'-diesters to regenerate the parent compound in the presence of human blood was demonstrated. 2',3'-Dipropionate esters of 2b and 4a were readily cleaved in a two-step reaction to regenerate the parent drug, on a time scale of two hours. The cleavage of a 2',3'-dihexanoate ester occurred at a slower rate. This indicates that the prodrugs are suitable as masked forms of the biologically active A3AR agonists and antagonists for future evaluation in vivo.