Search Results (28)

Liver failure is the 12th leading cause of death worldwide. Protein-bound toxins such as bilirubin are responsible for many complications of the disease. Binder dialysis systems use albumin or another binding molecule in dialysate and detoxifying sorbent columns to remove these toxins. Systems like the molecular adsorbent recirculating system and BioLogic-DT have existed since the 1990s, but survival benefits in randomized controlled trials have not been consistent. New binder dialysis systems, including open albumin dialysis and the Advanced Multi-Organ Replacement system, are being developed. Optimal conditions for binder dialysis have not been established. We developed and validated a computational model of bound solute dialysis. It predicted the impact of changing between two test setups using different polysulfone dialyzers (F3 and F6HPS). We then predicted the impact of varying the dialysate flow rate on toxin removal. We found that bilirubin removal declines with dialysate flow rate. This can be explained through a linear decline in free bilirubin membrane permeability. Our model quantifies this decline through a single parameter (polysulfone dialyzers). Validation for additional dialyzers and flow rates will be needed. This model will benefit clinical trials by predicting optimal dialyzer and flow rate conditions. Accounting for toxin adsorption onto the dialyzer membrane may improve results further. Full article

Non-immunoglobulin-based scaffold proteins (SPs) represent one of the key therapeutic target-specific and high-affinity binders in modern medicine. Among their cellular targets are signaling receptors, in particular, receptor tyrosine kinases, whose dysfunction leads to the development of cancer and other serious diseases. Successful applications of SPs have been reported for HER receptor type 2 (HER2), a member of the human epidermal growth factor receptor family that regulates cell growth and differentiation. To extend the blood residence of SPs and prevent their high accumulation in the kidneys, these proteins are often fused with serum albumin. Promising results for HER2-binding activity were obtained for SP G3 from the DARPins (Designed Ankyrin Repeat Proteins) family fused with an albumin-binding domain (ABD). Interestingly, the detected HER2–G3 binding strongly depended on the position of the G3 module in the sequence of the constructs. Further improvement of these constructs for biomedical applications requires deciphering the molecular mechanism responsible for this effect. Here, we investigate the structural and dynamic aspects of ABD–G3 and G3–ABD chimeras using NMR spectroscopy and molecular modeling. Based on biophysical data, we come to the conclusion that extensive inter-domain contacts form in both constructs, although their binding interfaces and complex stability are somewhat different. Also, it is shown that the domain linker plays an important role—it limits the accessibility of the detected protein–protein binding sites, depending on the order of the domains in the chimeric molecules. These results create a solid structural basis for the rational design of new effective SP constructs targeting the signaling receptors in cells. Full article

The negative environmental and social impacts of food waste accumulation can be mitigated by utilizing bio-refineries’ approach where food waste is revalorized into high-value products, such as prodigiosin (PG), using microbial bioprocesses. The diverse biological activities of PG position it as a promising compound, but its high production cost and promiscuous bioactivity hinder its wide application. Metal ions can modulate the electronic properties of organic molecules, leading to novel mechanisms of action and increased target potency, while metal complex formation can improve the stability, solubility and bioavailability of the parent compound. The objectives of this study were optimizing PG production through bacterial fermentation using food waste, allowing good quantities of the pure natural product for further synthesizing and evaluating copper(II) and zinc(II) complexes with it. Their antimicrobial and anticancer activities were assessed, and their binding affinity toward biologically important molecules, bovine serum albumin (BSA) and DNA was investigated by fluorescence emission spectroscopy and molecular docking. The yield of 83.1 mg/L of pure PG was obtained when processed meat waste at 18 g/L was utilized as the sole fermentation substrate. The obtained complexes CuPG and ZnPG showed high binding affinity towards target site III of BSA, and molecular docking simulations highlighted the affinity of the compounds for DNA minor grooves. Full article

Transthyretin binders have previously been used to improve the pharmacokinetic properties of small-molecule drug conjugates and could, thus, be utilized for radiopharmaceuticals as an alternative to the widely explored “albumin binder concept”. In this study, a novel PSMA ligand modified with a transthyretin-binding entity (TB-01) was synthesized and labeled with lutetium-177 to obtain [¹⁷⁷Lu]Lu-PSMA-TB-01. A high and specific uptake of [¹⁷⁷Lu]Lu-PSMA-TB-01 was found in PSMA-positive PC-3 PIP cells (69 ± 3% after 4 h incubation), while uptake in PSMA-negative PC-3 flu cells was negligible (<1%). In vitro binding studies showed a 174-fold stronger affinity of [¹⁷⁷Lu]Lu-PSMA-TB-01 to transthyretin than to human serum albumin. Biodistribution studies in PC-3 PIP/flu tumor-bearing mice confirmed the enhanced blood retention of [¹⁷⁷Lu]Lu-PSMA-TB-01 (16 ± 1% IA/g at 1 h p.i.), which translated to a high tumor uptake (69 ± 13% IA/g at 4 h p.i.) with only slow wash-out over time (31 ± 8% IA/g at 96 h p.i.), while accumulation in the PC-3 flu tumor and non-targeted normal tissue was reasonably low. Further optimization of the radioligand design would be necessary to fine-tune the biodistribution and enable its use for therapeutic purposes. This study was the first of this kind and could motivate the use of the “transthyretin binder concept” for the development of future radiopharmaceuticals. Full article

Introducing an albumin-binding entity into otherwise short-lived radiopharmaceuticals can be an effective means to improve their pharmacokinetic properties due to enhanced blood residence time. In the current study, DOTA-derivatized albumin binders based on 4-(p-iodophenyl)butanoate (DOTA-ALB-1 and DOTA-ALB-3) and 5-(p-iodophenyl)pentanoate entities (DOTA-ALB-24 and DOTA-ALB-25) without and with a hydrophobic 4-(aminomethyl)benzoic acid (AMBA) linker unit, respectively, were synthesized and labeled with lutetium-177 for in vitro and in vivo comparison. Overall, [¹⁷⁷Lu]Lu-DOTA-ALB-1 demonstrated ~3-fold stronger in vitro albumin-binding affinity and a longer blood residence time (T_50%IA ~8 h) than [¹⁷⁷Lu]Lu-DOTA-ALB-24 (T_50%IA ~0.8 h). Introducing an AMBA linker enhanced the albumin-binding affinity, resulting in a T_50%IA of ~24 h for [¹⁷⁷Lu]Lu-DOTA-ALB-3 and ~2 h for [¹⁷⁷Lu]Lu-DOTA-ALB-25. The same albumin binders without or with the AMBA linker were incorporated into 6R- and 6S-5-methyltetrahydrofolate-based DOTA-conjugates (¹⁷⁷Lu-RedFols). Biodistribution studies in mice performed with both diastereoisomers of [¹⁷⁷Lu]Lu-RedFol-1 and [¹⁷⁷Lu]Lu-RedFol-3, which comprised the 4-(p-iodophenyl)butanoate moiety, demonstrated a slower accumulation in KB tumors than those of [¹⁷⁷Lu]Lu-RedFol-24 and [¹⁷⁷Lu]Lu-RedFol-25 with the 5-(p-iodophenyl)pentanoate entity. In all cases, the tumor uptake was high (30–45% IA/g) 24 h after injection. Both diastereoisomers of [¹⁷⁷Lu]Lu-RedFol-1 and [¹⁷⁷Lu]Lu-RedFol-3 demonstrated high blood retention (3.8–8.7% IA/g, 24 h p.i.) and a 2- to 4-fold lower kidney uptake than the corresponding diastereoisomers of [¹⁷⁷Lu]Lu-RedFol-24 and [¹⁷⁷Lu]Lu-RedFol-25, which were more rapidly cleared from the blood (<0.2% IA/g, 24 h after injection). Kidney retention of the 6S-diastereoisomers of all ¹⁷⁷Lu-RedFols was consistently higher than that of the respective 6R-diastereoisomers, irrespective of the albumin binder and linker unit used. It was demonstrated that the blood clearance data obtained with ¹⁷⁷Lu-DOTA-ALBs had predictive value for the blood retention times of the respective folate radioconjugates. The use of these albumin-binding entities without or with an AMBA linker may serve for fine-tuning the blood retention of folate radioconjugates and also other radiopharmaceuticals and, hence, optimize their tissue distribution profiles. Dosimetry estimations based on patient data obtained with one of the most promising folate radioconjugates will be crucial to identify the dose-limiting organ, which will allow for selecting the most suitable folate radioconjugate for therapeutic purposes. Full article

Spray-dried animal plasma (SDAP) is a functional ingredient derived from healthy animal blood, used as a nutritional additive in livestock and pet nutrition. SDAP is rich in macronutrients, micronutrients, and bioactive compounds such as immunoglobulins, albumin, growth factors, peptides, transferrin, and enzymes. This review focuses on the chemical composition of SDAP from porcine, bovine, and poultry sources, including protein quality and mineral profile. SDAP enhances performance and health in monogastric farm animals, aquaculture, and pets. It promotes growth rates and feed intake due to its high digestibility and superior amino acid profile compared to other protein sources. In pigs, SDAP’s positive effects stem from tissue-specific actions in the gastrointestinal tract, impacting digestion, immunity, and barrier function. For poultry, SDAP shows promise as a substitute for antibiotic growth promoters, particularly in chick starter diets. SDAP contains functional proteins that regulate immune response, enhance intestinal health, and aid in stress conditions. It is also used as a binder in pet food, providing high protein content and other desirable properties. SDAP meets the dietary requirements of carnivorous pets, appealing to owners seeking animal-derived protein sources. Additionally, SDAP may help prevent cognitive impairment in senior dogs and cats. Full article

Chronic kidney disease is the gradual progression of kidney dysfunction and involves numerous co-morbidities, one of the leading causes of mortality. One of the primary complications of kidney dysfunction is the accumulation of toxins in the bloodstream, particularly protein-bound uremic toxins (PBUTs), which have a high affinity for plasma proteins. The buildup of PBUTs in the blood reduces the effectiveness of conventional treatments, such as hemodialysis. Moreover, PBUTs can bind to blood plasma proteins, such as human serum albumin, alter their conformational structure, block binding sites for other valuable endogenous or exogenous substances, and exacerbate the co-existing medical conditions associated with kidney disease. The inadequacy of hemodialysis in clearing PBUTs underscores the significance of researching the binding mechanisms of these toxins with blood proteins, with a critical analysis of the methods used to obtain this information. Here, we gathered the available data on the binding of indoxyl sulfate, p-cresyl sulfate, indole 3-acetic acid, hippuric acid, 3-carboxyl-4-methyl-5-propyl-2-furan propanoic acid, and phenylacetic acid to human serum albumin and reviewed the common techniques used to investigate the thermodynamics and structure of the PBUT–albumin interaction. These findings can be critical in investigating molecules that can displace toxins on HSA and improve their clearance by standard dialysis or designing adsorbents with greater affinity for PBUTs than HSA. Full article

Mycotoxins are toxic metabolites of molds. Chronic exposure to alternariol, zearalenone, and their metabolites may cause the development of endocrine-disrupting and carcinogenic effects. Alternariol-3-glucoside (AG) and alternariol-9-monomethylether-3-glucoside (AMG) are masked derivatives of alternariol. Furthermore, in mammals, zearalenone-14-glucuronide (Z14Glr) is one of the most dominant metabolites of zearalenone. In this study, we examined serum albumins and cyclodextrins (CDs) as potential binders of AG, AMG, and Z14Glr. The most important results/conclusions were as follows: AG and AMG formed moderately strong complexes with human, bovine, porcine, and rat albumins. Rat albumin bound Z14Glr approximately 4.5-fold stronger than human albumin. AG–albumin and Z14Glr–albumin interactions were barely influenced by the environmental pH, while the formation of AMG–albumin complexes was strongly favored by alkaline conditions. Among the mycotoxin–CD complexes examined, AMG–sugammadex interaction proved to be the most stable. CD bead polymers decreased the mycotoxin content of aqueous solutions, with moderate removal of AG and AMG, while weak extraction of Z14Glr was observed. In conclusion, rat albumin is a relatively strong binder of Z14Glr, and albumin can form highly stable complexes with AMG at pH 8.5. Therefore, albumins can be considered as affinity proteins with regard to the latter mycotoxin metabolites. Full article

Currently available hemodialysis (HD) membranes are unable to safely remove protein-bound uremic toxins (PBUTs), especially those bonded to human serum albumin (HSA). To overcome this issue, the prior administration of high doses of HSA competitive binders, such as ibuprofen (IBF), has been proposed as a complementary clinical protocol to increase HD efficiency. In this work, we designed and prepared novel hybrid membranes conjugated with IBF, thus avoiding its administration to end-stage renal disease (ESRD) patients. Two novel silicon precursors containing IBF were synthesized and, by the combination of a sol-gel reaction and the phase inversion technique, four monophasic hybrid integral asymmetric cellulose acetate/silica/IBF membranes in which silicon precursors are covalently bonded to the cellulose acetate polymer were produced. To prove IBF incorporation, methyl red dye was used as a model, thus allowing simple visual color control of the membrane fabrication and stability. These smart membranes may display a competitive behavior towards HSA, allowing the local displacement of PBUTs in future hemodialyzers. Full article

Introduction: secondary hyperparathyroidism (SHP) is frequent in patients with chronic kidney disease (CKD), particularly in those in dialysis. To treat this complication, the current options available include phosphorus restriction, phosphate binders, the inhibition of parathyroid hormone (PTH) synthesis and secretion by the supplementation of vitamin D or VDR activators, or the use of calcimimetics. Beyond the control of PTH, the effects of the treatment of SHP on other biomarkers of risk may represent an additional benefit for this population. In this study, we explore the benefits of current SHP treatment options, mainly paricalcitol and/or etelcalcetide in the inflammatory state of hemodialysis (HD) patients. Results: the study finally included 142 maintenance HD patients (5 patients were excluded) followed for 6 months (dialysis vintage 26 ± 30 months, mean age 70 years old, 73% women, 81% Spanish white, 47% diabetic). In this case, 52 patients were on regular treatment with paricalcitol for SHP and 25 patients were eligible to initiate etelcalcetide. The baseline serum levels of Ca, P, PTH, Ferritin, albumin, C-reactive protein (CRP), and other variables were measured. We found serum PTH levels showed an improvement after the treatment with etelcalcetide again paricalcitol and no treatment (p < 0.04). Of note, serum levels of CRP were significantly lower in a small group of patients (n = 11) receiving paricalcitol + etelcalcetide compared to paricalcitol or etelcalcetide alone. The proportion of patients with CRP within target ranges (≤1.0 mg/dL) increased significantly after combined treatment (p < 0.001). Conclusions: etelcalcetide proved to safely reduce the PTH levels without significant adverse events and the possibility of a synergic anti-inflammatory effect with the simultaneous use of Paricalcitol in HD patients. Full article

Alternaria mycotoxins, including alternariol (AOH), alternariol-9-monomethylether (AME), and their masked/modified derivatives (e.g., sulfates or glycosides), are common food contaminants. Their acute toxicity is relatively low, while chronic exposure can lead to the development of adverse health effects. Masked/modified metabolites can probably release the more toxic parent mycotoxin due to their enzymatic hydrolysis in the intestines. Previously, we demonstrated the complex formation of AOH with serum albumins and cyclodextrins; these interactions were successfully applied for the extraction of AOH from aqueous matrices (including beverages). Therefore, in this study, the interactions of AME, alternariol-3-sulfate (AS), and alternariol-9-monomethylether-3-sulfate (AMS) were investigated with albumins (human, bovine, porcine, and rat) and with cyclodextrins (sulfobutylether-β-cyclodextrin, sugammadex, and cyclodextrin bead polymers). Our major results/conclusions are the following: (1) The stability of mycotoxin–albumin complexes showed only minor species dependent variations. (2) AS and AMS formed highly stable complexes with albumins in a wide pH range, while AME–albumin interactions preferred alkaline conditions. (3) AME formed more stable complexes with the cyclodextrins examined than AS and AMS. (4) Beta-cyclodextrin bead polymer proved to be highly suitable for the extraction of AME, AS, and AMS from aqueous solution. (5) Albumins and cyclodextrins are promising binders of the mycotoxins tested. Full article

In the present study, SibuDAB, an albumin-binding PSMA ligand, was investigated in combination with actinium-225 and the data were compared with those of [²²⁵Ac]Ac-PSMA-617. In vitro, [²²⁵Ac]Ac-SibuDAB and [²²⁵Ac]Ac-PSMA-617 showed similar tumor cell uptake and PSMA-binding affinities as their ¹⁷⁷Lu-labeled counterparts. The in vitro binding to serum albumin in mouse and human blood plasma, respectively, was 2.8-fold and 1.4-fold increased for [²²⁵Ac]Ac-SibuDAB as compared to [¹⁷⁷Lu]Lu-SibuDAB. In vivo, this characteristic was reflected by the longer retention of [²²⁵Ac]Ac-SibuDAB in the blood than previously seen for [¹⁷⁷Lu]Lu-SibuDAB. Similar to [²²⁵Ac]Ac-PSMA-617, [²²⁵Ac]Ac-SibuDAB was well tolerated at 30 kBq per mouse. Differences in blood cell counts were observed between treated mice and untreated controls, but no major variations were observed between values obtained for [²²⁵Ac]Ac-SibuDAB and [²²⁵Ac]Ac-PSMA-617. [²²⁵Ac]Ac-SibuDAB was considerably more effective to treat PSMA-positive tumor xenografts than [²²⁵Ac]Ac-PSMA-617. Only 5 kBq per mouse were sufficient to eradicate the tumors, whereas tumor regrowth was observed for mice treated with 5 kBq [²²⁵Ac]Ac-PSMA-617 and only one out of six mice survived until the end of the study. The enhanced therapeutic efficacy of [²²⁵Ac]Ac-SibuDAB as compared to that of [²²⁵Ac]Ac-PSMA-617 and reasonable safety data qualify this novel radioligand as a candidate for targeted α-therapy of prostate cancer. Full article

Somatostatin receptor subtype 2 (SSTR2) has become an essential target for radionuclide therapy of neuroendocrine tumors (NETs). JR11 was introduced as a promising antagonist peptide to target SSTR2. However, due to its rapid blood clearance, a better pharmacokinetic profile is necessary for more effective treatment. Therefore, two JR11 analogs (8a and 8b), each carrying an albumin binding domain, were designed to prolong the blood residence time of JR11. Both compounds were labeled with lutetium-177 and evaluated via in vitro assays, followed by in vivo SPECT/CT imaging and ex vivo biodistribution studies. [¹⁷⁷Lu]Lu-8a and [¹⁷⁷Lu]Lu-8b were obtained with high radiochemical purity (>97%) and demonstrated excellent stability in PBS and mouse serum (>95%). [¹⁷⁷Lu]Lu-8a showed better affinity towards human albumin compared to [¹⁷⁷Lu]Lu-8b. Further, 8a and 8b exhibited binding affinities 30- and 48-fold lower, respectively, than that of the parent peptide JR11, along with high cell uptake and low internalization rate. SPECT/CT imaging verified high tumor accumulation for [¹⁷⁷Lu]Lu-8a and [¹⁷⁷Lu]Lu-JR11 at 4, 24, 48, and 72 h post-injection, but no tumor uptake was observed for [¹⁷⁷Lu]Lu-8b. Ex vivo biodistribution studies revealed high and increasing tumor uptake for [¹⁷⁷Lu]Lu-8a. However, its extended blood circulation led to an unfavorable biodistribution profile for radionuclide therapy. Full article

Nonporous corundum powder, known as an abrasive material in the industry, was functionalized covalently with protein binders to isolate and enrich specific proteins from complex matrices. The materials based on corundum were characterized by TEM, ESEM, BET, DLS, EDS, and zeta potential measurements. The strong Al-O-P bonds between the corundum surface and amino phosphonic acids were used to introduce functional groups for further conjugations. The common crosslinker glutaraldehyde was compared with a hyperbranched polyglycerol (PG) of around 10 kDa. The latter was oxidized with periodate to generate aldehyde groups that can covalently react with the amines of the surface and the amino groups from the protein via a reductive amination process. The amount of bound protein was quantified via aromatic amino acid analysis (AAAA). This work shows that oxidized polyglycerol can be used as an alternative to glutaraldehyde. With polyglycerol, more of the model protein bovine serum albumin (BSA) could be attached to the surface under the same conditions, and lower non-specific binding (NSB) was observed. As a proof of concept, IgG was extracted with protein A from crude human plasma. The purity of the product was examined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). A binding capacity of 1.8 mg IgG per gram of corundum powder was achieved. The advantages of corundum include the very low price, extremely high physical and chemical stability, pressure resistance, favorable binding kinetics, convenient handling, and flexible application. Full article

Peptide receptor radionuclide therapy (PRRT) is an emerging approach for patients with unresectable or metastatic tumors. Our previously optimized RGD peptide (3PRGD₂) has excellent targeting specificity for a variety of integrin α_vβ₃/α_vβ₅-positive tumors and has been labeled with the therapeutic radionuclide [¹⁷⁷Lu]LuCl₃ for targeted radiotherapy of tumors. However, the rapid clearance of [¹⁷⁷Lu]Lu-DOTA-3PRGD₂ (¹⁷⁷Lu-3PRGD₂) in vivo requires two doses of 111 MBq/3 mCi to achieve effective tumor suppression, limiting its further clinical application. Albumin binders have been attached to drugs to facilitate binding to albumin in vivo to prolong the drug half-life in plasma and obtain long-term effects. In this study, we modified 3PRGD₂ with albumin-binding palmitic acid (Palm-3PRGD₂) and then radiolabeled Palm-3PRGD₂ with ¹⁷⁷Lu. [¹⁷⁷Lu]Lu-DOTA-Palm-3PRGD₂ (¹⁷⁷Lu-Palm-3PRGD₂) retained a specific binding affinity for integrin α_vβ₃/α_vβ₅, with an IC₅₀ value of 5.13 ± 1.16 nM. Compared with ¹⁷⁷Lu-3PRGD₂, the ¹⁷⁷Lu-Palm-3PRGD₂ circulation time in blood was more than 6 times longer (slow half-life: 73.42 min versus 11.81 min), and the tumor uptake increased more than fivefold (21.34 ± 4.65 %IA/g and 4.11 ± 0.70 %IA/g at 12 h post-injection). Thus, the significant increase in tumor uptake and tumor retention resulted in enhanced efficacy of targeted radiotherapy, and tumor growth was completely inhibited by a single and relatively lowdose of 18.5 MBq/0.5 mCi. Thus, ¹⁷⁷Lu-Palm-3PRGD₂ shows great potential for clinical application. Full article