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Bees provide essential ecosystem services and help maintain floral biodiversity. However, there is an ongoing decline of wild and domesticated bee species. Since agricultural pesticide use is a key driver of this process, there is a need for a protective risk assessment. To achieve a more protective registration process, two bee species, Osmia bicornis/Osmia cornuta and Bombus terrestris, were proposed by the European Food Safety Authority as additional test surrogates to the honey bee Apis mellifera. We investigated the acute toxicity (median lethal dose, LD50) of multiple commercial insecticide formulations towards the red mason bee (O. bicornis) and compared these values to honey bee regulatory endpoints. In two thirds of all cases, O. bicornis was less sensitive than the honey bee. By applying an assessment factor of 10 on the honey bee endpoint, a protective level was achieved for 87% (13 out 15) of all evaluated products. Our results show that O. bicornis is rarely an adequate additional surrogate species for lower tier risk assessment since it is less sensitive than the honey bee for the majority of investigated products. Given the currently limited database on bee species sensitivity, the honey bee seems sufficiently protective in acute scenarios as long as a reasonable assessment factor is applied. However, additional surrogate species can still be relevant for ecologically meaningful higher tier studies.

Active targeting and specific drug delivery to parenchymal liver cells is a promising strategy to treat various liver disorders. Here, we modified synthetic lipid-based nanoparticles with targeting peptides derived from the hepatitis B virus large envelope protein (HBVpreS) to specifically target the sodium-taurocholate cotransporting polypeptide (NTCP; SLC10A1) on the sinusoidal membrane of hepatocytes. Physicochemical properties of targeted nanoparticles were optimized and NTCP-specific, ligand-dependent binding and internalization was confirmed in vitro. The pharmacokinetics and targeting capacity of selected lead formulations was investigated in vivo using the emerging zebrafish screening model. Liposomal nanoparticles modified with 0.25 mol% of a short myristoylated HBV derived peptide, that is Myr-HBVpreS2-31, showed an optimal balance between systemic circulation, avoidance of blood clearance, and targeting capacity. Pronounced liver enrichment, active NTCP-mediated targeting of hepatocytes and efficient cellular internalization were confirmed in mice by 111In gamma scintigraphy and fluorescence microscopy demonstrating the potential use of our hepatotropic, ligand-modified nanoparticles.

Infections caused by multidrug-resistant bacteria are a global emerging problem. New antibiotics that rely on innovative modes of action are urgently needed. Ranalexin is a potent antimicrobial peptide (AMP) produced in the skin of the American bullfrog Rana catesbeiana. Despite strong antimicrobial activity against Gram-positive bacteria, ranalexin shows disadvantages such as poor pharmacokinetics. To tackle these problems, a ranalexin derivative consisting exclusively of d-amino acids (named danalexin) was synthesized and compared to the original ranalexin for its antimicrobial potential and its biodistribution properties in a rat model. Danalexin showed improved biodistribution with an extended retention in the organisms of Wistar rats when compared to ranalexin. While ranalexin is rapidly cleared from the body, danalexin is retained primarily in the kidneys. Remarkably, both peptides showed strong antimicrobial activity against Gram-positive bacteria and Gram-negative bacteria of the genus Acinetobacter with minimum inhibitory concentrations (MICs) between 4 and 16 mg/L (1.9–7.6 µM). Moreover, both peptides showed lower antimicrobial activities with MICs ≥32 mg/L (≥15.2 µM) against further Gram-negative bacteria. The preservation of antimicrobial activity proves that the configuration of the amino acids does not affect the anticipated mechanism of action, namely pore formation.

Background Malaria still poses a significant burden on global health, with millions of cases reported annually and rising resistance to current treatments, emphasizing the need for new therapeutic strategies. Fosmidomycin, initially recognized for its antibacterial properties, has emerged as a promising candidate in the fight against malaria. Methods In this study, a sensitive and robust LC–MS/MS method for quantifying fosmidomycin in human and rat plasma was developed and validated. Plasma samples were prepared using a simple protein precipitation method with 10% trichloroacetic acid (TCA). The assay featured a rapid run time of 5 min, and validation was performed according to the European Medicines Agency's guidelines. Results The method validation confirmed its selectivity, linearity, accuracy, precision, and stability. Notably, the calibration range was established from 0.25 to 15 mg/L, demonstrating improvements over previous methodologies with lower limits of quantification of 0.5–1.0 mg/L. Using the developed LC–MS/MS method, plasma samples were analysed from a clinical trial conducted in Gabon, as well as from a pharmacokinetic study involving male Wistar rats, revealing viable pharmacokinetic profiles for fosmidomycin. Conclusions These findings confirm the utility of the developed analytical method for supporting the clinical development of fosmidomycin as a potential therapy for malaria.

Despite the nowadays available plentitude of strategies to selectively introduce functional surface modification of liposomes, in preclinical research this process is still primarily performed after liposomal preparation utilizing comprised activated phospholipids with functionalized head groups. However, because these activated lipids are present during the liposomal preparation process, they can cross-react with incorporated drugs, especially the particularly often utilized active esters and maleimide groups. Macromolecular drugs, being composed of amino acids, are particularly prone to such cross-reactions due to their often multiple reactive functionalities such as amino and disulfide groups. To demonstrate this impact on the formulation in liposomal surface modification, we assessed the extent of cross-reaction during the liposomal preparation of two activated phospholipids with typically used head group functionalized phospholipids, with the two peptide drugs vancomycin and insulin comprising disulfide and amino functionalities. Both drugs revealed a considerable fraction of covalent modification (estimated 2 to 12%) generated during the liposome preparation process with comprised activated lipids. Modification of the active pharmaceutical ingredients (APIs) was determined by high-resolution mass spectrometric analysis. These findings clearly demonstrate the non-negligibility of potential cross reactions using the post preparation liposomal surface modification strategy in preclinical research.

To treat certain vitreoretinal diseases, the vitreous body, a hydrogel composed of mostly collagen and hyaluronic acid, must be removed. After vitrectomy surgery, the vitreous cavity is filled with an endotamponade. Previously, pre-clinical hydrogel-based vitreous body substitutes either made from uncrosslinked monomers (1st generation), preformed crosslinked polymers (2nd generation), or in situ gelating polymers (3rd generation) have been developed. Forward light scattering is a measure of Stray light induced by optical media, when increased, causing visual disturbance and glare. During pinhole surgery, the hydrogels are injected into the vitreous cavity through a small 23G-cannula. The aim of this study was to assess if and to what extent forward light scattering is induced by vitreous body replacement hydrogels and if Stray light differs between different generations of vitreous body hydrogel replacements due to the different gelation mechanisms and fragmentation during injection. A modified C-Quant setup was used to objectively determine forward light scattering. In this study, we found that the 1st and 3rd generation vitreous body replacements show very low stray light levels even after injection (2.8 +/− 0.4 deg2/sr and 0.2 +/− 0.2 deg2/sr, respectively) as gel fragmentation and generation of interfaces is circumvented. The 2nd generation preformed hydrogels showed a permanent increase in stray light after injection that will most likely lead to symptoms such as glare when used in patients (11.9 +/− 0.9 deg2/sr). Stray light of the 2nd generation hydrogels was 3- and 2-fold increased compared to juvenile and aged vitreous bodies, respectively. In conclusion, this significant downside in the forward light scattering of the 2nd generation hydrogels should be kept in mind when developing vitreous body replacement strategies, as any source of stray light should be minimized in patients with retinal comorbidities.

Multidrug-resistant bacteria represent one of the most important health care problems worldwide. While there are numerous drugs available for standard therapy, there are only a few compounds capable of serving as a last resort for severe infections. Therefore, approaches to control multidrug-resistant bacteria must be implemented. Here, a strategy of reactivating the established glycopeptide antibiotic vancomycin by structural modification with polycationic peptides and subsequent fatty acid conjugation to overcome the resistance of multidrug-resistant bacteria was followed. This study especially focuses on the structure–activity relationship, depending on the modification site and fatty acid chain length. The synthesized conjugates showed high antimicrobial potential on vancomycin-resistant enterococci. We were able to demonstrate that the antimicrobial activity of the vancomycin-lipopeptide conjugates depends on the chain length of the attached fatty acid. All conjugates showed good cytocompatibility in vitro and in vivo. Radiolabeling enabled the in vivo determination of pharmacokinetics in Wistar rats by molecular imaging and biodistribution studies. An improved biodistribution profile in comparison to unmodified vancomycin was observed. While vancomycin is rapidly excreted by the kidneys, the most potent conjugate shows a hepatobiliary excretion profile. In conclusion, these results demonstrate the potential of the structural modification of already established antibiotics to provide highly active compounds for tackling multidrug-resistant bacteria.

Lipid nanoparticles, including liposomes, have emerged as promising vehicles for the delivery of a variety of therapeutics. Several formulations have been approved and are used in medical practice—the COVID-19 mRNA vaccines represent the most recent milestone. Achieving effective oral delivery would elevate the potential of these formulations. Therefore, this study investigates the oral application of mRNA using liposomes as a nanocarrier system. A cyclic cell-penetrating peptide was coupled to the liposomal surface to allow uptake into the intestinal mucosal cells. The liposomes were loaded with mRNA (up to 112 µg/mL) and characterized in terms of their size (Z-average; 135.4 nm ± 1.1 nm), size distribution (polydispersity index (PDI); 0.213 ± 0.007 nm), surface charge (2.89 ± 0.27 mV), structure, lamellarity (multilamellar liposomes), and cargo capacity (>90%). The impact of freeze-drying and long-term storage of liposomal formulations was examined, and in vitro experiments on Caco-2 cells were conducted to evaluate the cytotoxicity of the liposomal formulations and demonstrate the uptake of the liposomes into cells. The efficiency of the formulations could be proven in vitro. When compared to control liposomes and 1,2-dioleoyl-3-trimethylammonium propane (DOTAP)-liposomes, the new formulations exhibited significantly enhanced uptake in Caco-2 cells, an immortalized epithelial cell line. Moreover, the cytocompatibility of the formulations could be proven by the absence of cytotoxic effects on the viability of Caco-2 cells. Hence, this liposomal drug delivery system holds significant promise for the oral delivery of mRNA.

In this study, the potential of liposomes containing tetraether lipids (TELs) and cell‐penetrating peptides (CPPs) as a platform technology for oral delivery of peptides, using the glucagon‐like peptide 1 (GLP‐1) analogs semaglutide, exenatide, and dulaglutide as model compounds, was investigated. As this technology was proven effective in vitro and in vivo in mice and dogs for a small, hydrophilic glycopeptide drug (vancomycin) before, the focus of this study was to evaluate the applicability for peptide therapeutics with higher molecular weight (exenatide–4186.8 Da, semaglutide–4113.6 Da, and dulaglutide–59670.6 Da) and different physico‐chemical properties (semaglutide). For this purpose, liposomal formulations were prepared by dual centrifugation and characterized by size, polydispersity index, zeta potential, morphology, and encapsulation efficiency. All GLP‐1 analogs liposomal formulations revealed promising liposomal characteristics and were subsequently investigated with respect to uptake on colon‐carcinoma‐2 (CaCo‐2) cells and biocompatibility. Besides the high biocompatibility, a highly increased uptake of all three GLP‐1 analogs encapsulated into the liposomes containing TELs and CPPs in comparison to the free compound could be demonstrated on CaCo‐2 cells. These findings highlight the great potential of this liposomal technology for oral delivery of peptide therapeutics in general. Liposomes functionalized with tetraether lipids and cell‐penetrating peptides are explored as a platform technology for oral peptide delivery. Therefore, peptide drugs (GLP‐1 analogs) with different sizes and physicochemical properties are used as model drugs. The liposomes show favorable characteristics and increased cellular uptake by a simulated intestinal epithelium.

Background The removal of high-viscosity silicone oil in retinal surgery is time-intensive. In this laboratory and porcine eye study, we evaluated the efficiency of novel extraction techniques, namely shortened polyimide-cannulas, an extraction sleeve and an experimental luer-trocar system, for commercially available silicone oils. Methods The volume of silicone oil after a 5-min removal time was quantified. The feasibility of all studied techniques was additionally tested in vitrectomized porcine eyes. Siluron 1000, 2000, 5000 and Xtra, as well as Densiron 68 and Densiron Xtra were examined. Results Shortening the 23G-polyimide-cannula from 6 mm up to 1.5 mm led to a significantly higher mean aspirated volume (e.g., 1 ml/min to 1.7 ml/min for Siluron Xtra). The extraction sleeve and luer-trocar increased the flow threefold compared to the shortest polyimide cannulas at 23G (5.2 ml/min and 5.2 ml/min vs 1.7 ml/min for Siluron Xtra, respectively). The extraction sleeve and luer-trocar system reached a similar flow at 27G as the best performing 23G-cannula. Angulation and movement of the eye was possible with the 2 mm-cannula, no angulation was possible when using the extraction sleeve. Stability and control were not impaired with the experimental luer-trocar setup. Conclusion Shorter polyimide-cannulas and extraction sleeves increase the extraction flow but may decrease stability during surgery. The luer-trocar system facilitates rapid removal while offering great stability and control. Small 27G silicone oil removal is possible and time efficient.