Fluorinated amphiphiles are gaining attention in nanomedicine for their unique self-assembly properties and stability, offering opportunities for intracellular drug delivery platforms. We synthesized a tunable series of "fluorosomes" (amine, glutamine, glutamic acid, succinic acid, folate terminus, FITC reporter) based on monodisperse poly(ethylene glycol) (PEG) that spontaneously assemble into nanoparticles with terminal-group-dependent zeta-potentials and morphologies (DLS/TEM). Using a suite of cell lines, we examined cellular uptake, intracellular localization, and cytotoxicity, revealing that despite the superhydrophobic nature of longer fluorinated chains, surface charge still plays a role in modulating nanoparticle - cell interactions. Confocal microscopy revealed a distinct and conserved perinuclear distribution pattern consistent with an endoplasmic reticulum association. This suggests that the observed trafficking occurs predominantly in the proximity of the ER and is largely independent of terminal charge, with folate representing a notable exception. The intracellular distribution pattern suggests a potential preference for nonlysosomal trafficking pathways, possibly involving caveolae-mediated endocytosis, although further mechanistic studies are required to confirm this hypothesis. In vivo NIR imaging of charged variants showed rapid hepatic accumulation, followed by hepatobiliary transit to the intestine and residual signals in the kidneys and lymph nodes through 24-48 h. These data position fluorosomes as possible intracellular carriers for future nanomedicine applications.

Diving involves unique physiological stressors and environmental exposures that may affect health outcomes. Long-term survival among divers results from a complex interaction between potentially harmful exposures related to the hyperbaric environment and oxidative stress, diving-related accidents, as well as protective factors such as physical fitness, psychological resilience, and socioeconomic status. The aim of this study was to evaluate long-term survival in a cohort of Czech divers compared with the general population. Data from 1,076 divers registered in the DIVE-PFO Registry (2005–2024) were linked with the National Health Information System to determine mortality and causes of death. Observed survival was estimated using the Kaplan–Meier method; expected survival was based on national life tables to calculate relative survival via the Pohar-Perme method. Over 10,294 person-years of follow-up, there were 15 deaths (1.4

PURPOSE:Endogenous renal chemical exchange saturation transfer (CEST) imaging enables contrast-agent-free assessment of renal metabolism but is highly sensitive to respiratory motion. Existing approaches, such as timed breathing, require high patient compliance or preclinical mechanical ventilation, limiting clinical translation. We evaluated a free-breathing prospective respiratory triggering method that allows continuous saturation during active breathing while adaptively aligning image acquisition with the expiratory phase. METHODS:Prospective triggering was based on a modified real-time respiratory signal, with a temporal shift continuously updated according to the current respiratory rate. Simulations assessed its performance across saturation durations of 1-6 s, respiratory rates representative of preclinical and clinical settings (f = 8-90 bpm), and varying respiratory frequency (CV = 0%-25%). Results were compared to conventional real-time triggering. For in vivo validation, prospective triggering was implemented on a preclinical 7 T MRI system using a Raspberry Pi-based hardware and software. Six mice underwent CEST imaging with saturation durations of 1, 3, and 5 s using both real-time and prospective triggering, and the Mean Squared Error of Lorentzian fit was used to compare the two approaches. RESULTS:The real-time trigger error shows a periodic dependence on respiratory frequency, which diminishes with increasing variability, whereas the prospective trigger reduces this periodicity. In vivo, prospective triggering significantly (p < 0.05) reduced motion-induced scattering in the Z-spectrum for saturation times up to 3 s and enabled the detection of distinct metabolic contrasts across renal compartments. CONCLUSION:Prospective triggering effectively reduces motion artifacts in preclinical renal CEST imaging.

Nanomedicines have shown significant potential in advancing treatment for a variety of cancer types. Despite these advances, further research is essential to improve the efficacy and selectivity of anticancer nanomedicines, particularly by developing delivery systems capable of achieving high efficacy with minimal off-target toxicity. We herein report novel pH-responsive block copolymer-drug conjugates based on poly(N-(2-hydroxypropyl) methacrylamide) (PHPMAm) and benzoic imine linkages, uniquely combining stealth performance with tunable, acid-triggered drug release. By engineering block and random copolymer architectures with controlled hydrophilic shell length, we systematically evaluated how polymer structure governs self-assembly, release kinetics, and therapeutic outcomes. The conjugates achieve up to 10-12 wt% doxorubicin loading, with pH-selective release half-live spanning within 2-40 h. In contrast to most Schiff base polymer-drug systems limited to in vitro data, the synthesized polymer-drug conjugates demonstrated outstanding antitumor efficacy and 100 % survival for spherical assemblies in aggressive murine lymphoma models, with superior safety. Unlike conventional PEG systems, PHPMAm-based copolymers can potentially avoid anti-PEG immunogenicity and exhibit exceptional in vivo stability and tumor accumulation.

Collagen membranes are widely used in tissue and bone engineering, including guided bone regeneration (GBR). For effective and uninterrupted bone healing, a GBR membrane must maintain its functionality for an initial critical period of 4 weeks. A novel carp collagen sponge has already shown promise as a wound coating and vascular graft coating, making it a candidate for GBR applications as well. To enhance the mechanical properties and longevity of GBR membranes, we modified the basic carp collagen membrane with combinations of l-lactide, ε-caprolactone, d,l-lactide, and glycolide in various molar ratios. While traditional methods rely on histological evaluation to assess the degradation pattern and therefore suitability of GBR membranes ex vivo, this study employed micro-MRI as an innovative, noninvasive approach to monitor the in vivo degradation of carp collagen membrane and its polymer-modified variants. Our findings demonstrated that micro-MRI is a reliable and effective method for visualizing collagen membrane degradation in vivo, up to scaffold disintegration. Among the variants tested, collagen GBR membrane coated with d,l-lactide and glycolide in a 50:50 M ratio emerged as the most suitable for GBR purposes. However, since this study was conducted in the subcutaneous tissue of a rat model, further research is required to determine the behavior of carp collagen GBR membrane variants on bony surfaces.

Photo-crosslinkable gelatin-based hydrogels hold great promise for tissue engineering and regenerative medicine. However, monitoring these hydrogels in vivo remains challenging and limits their further development and clinical translation. Here, we address this limitation by utilizing a gelatin-based hydrogel that incorporates the radiopaque compound 5-acrylamido-2,4,6-triiodoisophthalic acid (AATIPA). In an in vivo study spanning over 400 days, we monitor the degradation kinetics of these hydrogels using computed tomography and ultrasonography. We synthesize three distinct AATIPA-containing hydrogels and implant them subcutaneously into mice. Hydrogels with high crosslink density show minimal degradation, while those with lower crosslinking densities degrade within approximately three months. Histological evaluation reveals that the scaffolds are replaced by adjacent adipose tissue. In vitro, adipose-derived stem cells differentiate into the adipogenic lineage, corroborating the in vivo findings. These results highlight the potential of these hydrogels for adipose tissue engineering by enabling in vivo monitoring and offering tailored degradation profiles. Photo-crosslinkable gelatin-based hydrogels hold promise for tissue engineering, but in vivo monitoring challenges hinder their clinical translation. Here, radiopaque, 3D-printable hydrogels with tailored degradation profiles, enable long-term in vivo monitoring and demonstrate potential for adipose tissue engineering by facilitating scaffold colonization and replacement by adipose tissue

The Radiochemical Laboratory of the Institute of Macromolecular Chemistry, Czech Academy of Sciences (CAS), was established in 2009 to advance the synthesis and characterization of radiolabeled polymers and nanoparticles. From the outset, close collaboration with the biological and medical departments of the First Faculty of Medicine, Charles University, proved essential. This article summarizes a fifteen-year collaboration, from the earliest experiments at the Institute of Biophysics and Informatics to the current era of the Center for Advanced Preclinical Imaging (CAPI). The partnership has led to joint publications, projects, and patents with implications for medicine. The text further provides an overview of technical equipment, practical requirements for in vivo experiments, and the economic aspects of preclinical research.

Plasmonic titanium nitride (TiN) nanoparticles are emerging nanomaterials possessing several orders of magnitude higher absorption cross section, but also exhibit higher photostability compared to conventional photosenzitizers. In the recent years, TiN has emerged as a highly effective electrocatalytic and environmentally friendly material with good biocompatibility. Its unique physicochemical properties and cost-effectiveness are essential for wide utilization in biomedicine. However, the effect of morphology of TiN on the photothermal therapy (PTT) efficiency has not been studied yet. Here, TiN nanocrystals of two precisely defined morphologies - nanobars and nanospheres - were prepared by unique pseudomorphic conversion of TiO2 nanowires and nanospheres via nitridation at 800 °C. Due to their multiple plasmonic resonances, the resulting materials show broad optical absorption spanning the entire solar spectrum and biological window including the NIR-I (750 – 1000 nm) and NIR-II (1000 – 1350 nm). Using low power illumination 318 mW/cm2 and NIR LED irradiation 940 nm, we observed a morphology-dependent PTT bioactivity, with the TiN nanobars being more efficient in cancer HeLa cells killing, while nanospheres showed higher antimicrobial activity toward Staphylococcus aureus and Escherichia coli bacteria strains. Moreover, acute and long-term in vitro biocompatibility together with in vivo monitoring of biodistribution showing enhanced permeability and retention (EPR) effect were confirmed by photoacoustic (PA) imaging in tumor bearing mice (C57BL/6J albino, EL4 lymphoma cell line). Thus, both TiN morphologies - nanobars and nanospheres are promising candidates in theranostic application via PTT therapy and PA imaging.

Background Targeted alpha therapy (TAT) is an effective option for cancer treatment. To maximize its efficacy and minimize side effects, carriers must deliver radionuclides to target tissues. Most of the nuclides used in TAT decay via the alpha cascade, producing several radioactive daughter nuclei with sufficient energy to escape from the original carrier. Therefore, studying these daughter atoms is crucial in the search for new carriers. Nanoparticles have potential as carriers due to their structure, which can prevent the escape of daughter atoms and reduce radiation exposure to non-target tissues. This work focuses on determining the released activity of Fr-221 and Bi-213 resulting from the decay of Ac-225 labelled TiO2 nanoparticles. Results Labelling of TiO2 nanoparticles has shown high sorption rates of Ac-225 and its progeny, Fr-221 and Bi-213, with over 92 % of activities sorbed on the nanoparticle surface for all measured radionuclides. However, in the quasi-dynamic in vitro system, the released activity of Fr-221 and Bi-213 is strongly dependent on the nanoparticles concentration, ranging from 15 % for a concentration of 1 mg/mL to approximately 50 % for a nanoparticle concentration of 10 mu g/mL in saline solution. The released activities of Bi-213 were lower, with a maximum value of around 20 % for concentrations of 0.05, 0.025, and 0.01 mg/mL. The leakage of Ac-225 and its progeny was tested in various biological matrices. Minimal released activity was measured in saline at around 10 % after 48 h, while the maximum activity was measured in blood serum and plasma at 20 %. The amount of Ac-225 released into the media was minimal (<3 %). The in vitro results were confirmed in a healthy mouse model. The difference in %ID/g was clearly visible immediately after dissection and again after 6 h when Bi-213 reached equilibrium with Ac-225. Conclusion The study verified the potential release of Ac-225 progeny from the labelled TiO2 nanoparticles. Experiments were performed to determine the dependence of released activity on nanoparticle concentration and the biological environment. The results demonstrated the high stability of the prepared Ac-225@TiO2 NPs and the potential release of progeny over time. In vivo studies confirmed our hypothesis. The data obtained suggest that the daughter atoms can escape from the original carrier and follow their own biological pathways in the organism.

Magnetic nanoparticles have been at the center of biomedical research for decades, primarily for their applications in magnetic resonance imaging (MRI) and magnetic particle imaging (MPI). Superparamagnetic particles, typically based on iron oxide crystals, are effective in both modalities, although each requires distinct magnetic properties for optimal performance. We investigated the performance of nanoparticles based on a nickel-substituted ferrite core and compared them to standard maghemite iron oxide nanoparticles. We synthesized γ-Fe2O3 and Ni x Fe2-x O3 nanoparticles and coated them with a statistical copolymer poly-(N,N-dimethylacrylamide-co-acrylic acid). In vitro testing included X-ray diffraction (XRD), Mössbauer spectroscopy, magnetometry, magnetic resonance relaxometry, magnetic particle spectroscopy, and imaging. In vivo testing involved monitoring of nanoparticle biodistribution using MPI and MRI after intracardial application in a murine model. Mössbauer spectra suggest that the Ni-substituted nanoparticles consist of a stoichiometric NiFe2O4 ferrite and a poorly crystalline antiferromagnetic iron-(III) oxide-hydroxide phase. Amorphous-like impurities in Ni x Fe2-x O3 nanoparticles were probably responsible for lower saturation magnetization than that of γ-Fe2O3 nanoparticles, as was proved by magnetometry, which led to lower r 2 relaxivity. However, MPI revealed a higher signal in the spectrum and superior imaging performance of Ni x Fe2-x O3 compared to γ-Fe2O3 particles, likely due to shorter Néél and Brownian relaxation times. Both types of nanoparticles showed similar performance in bimodal MRI/MPI imaging in vivo. They were detected in the liver immediately after application and appeared in the spleen within 24 h. Long-term localization in the lymph nodes was also observed. Substituting an iron with a nickel ion in the core altered the magnetic properties, leading to lower saturation magnetization and an increased signal in the magnetic particle spectra, which enhanced their performance in MPI. This study demonstrates that γ-Fe2O3 and Ni x Fe2-x O3 nanoparticles are both suitable for combined MRI/MPI imaging; magnetic particle imaging provides a highly specific signal for anatomical magnetic resonance images.

Myeloid cell leukemia-1 (MCL1) is among the most overexpressed proteins in tumors. MCL1 contributes to tumorigenesis by antagonizing apoptosis. However, apoptosis-unrelated functions are emerging. Screening an array of signaling switches identifies mTORC1 to be modulated by MCL1 but not by the anti-apoptotic Bcl-2 or Bcl-xL. mTORC1 is a central metabolic regulator. MCL1 impacts metabolism via modulating the expression of hexokinase 2 (HK2) in an mTORC1-dependent manner, which ultimately contributes to the tumor-promoting effects of MCL1. MCL1 inhibitors suppress mTORC1 in tumor cells but are associated with cardiotoxicity due to mTORC1 inhibition in the heart. Dietary leucine supplementation rescues mTORC1 signaling in the hearts of humanized Mcl-1 mice and greatly ameliorates the cardiotoxicity of MCL1 inhibitors. Taken together, here we describe tumor-promoting roles for MCL1 in regulating mTORC1 signaling and subsequently in bioenergetics, besides its role in antagonizing apoptosis, identifying MCL1 as a hinge of cell bioenergetics and survival.

Hyperbaric oxygen therapy (HBOT) elevates the partial pressure of life-sustaining oxygen (pO2), thereby saving lives. However, HBOT can also cause toxic effects like lung and retinal damage (peripheral oxygen toxicity) and violent myoclonic seizures (central nervous system (CNS) toxicity). The mechanisms behind these effects are not fully understood, hindering the development of effective therapies and preventive strategies. Herein, we critically reviewed the literature to understand CNS oxygen toxicity associated with HBOT to elucidate their mechanism, treatment, and prevention. We provide evidence that (1) increased pO2 increases reactive oxygen species (ROS) concentration in tissues, which irreversibly alters cell receptors, causing peripheral oxygen toxicity and contributing to CNS oxygen toxicity. Furthermore, (2) increased ROS concentration in the brain lowers the activity of glutamic decarboxylase (GD), which lowers concentrations of inhibitory neurotransmitter γ-aminobutyric acid (GABA), thereby contributing to the onset of HBOT-derived seizures. We provide long-overlooked evidence that (3) elevated ambient pressure directly inhibits GABAA, glycine and other receptors, leading to the rapid onset of seizures. Additionally, (4) acidosis facilitates the onset of seizures by an unknown mechanism. Only a combination of these mechanisms explains most phenomena seen in peripheral and CNS oxygen toxicity. Based on these proposed intertwined mechanisms, we suggest administering antioxidants (lowering ROS concentrations), pyridoxine (restoring GD activity), low doses of sedatives/anesthetics (reversing inhibitory effects of pressure on GABAA and glycine receptors), and treatment of acidemia before routine HBOT to prevent peripheral and CNS oxygen toxicity. Theoretically, similar preventive strategies can be applied before deep-sea diving to prevent life-threatening convulsions.

Gelatin-based hydrogels emerged as promising biodegradable cell-compatible 3D-printable materials with tunable mechanical properties that serve tissue engineering and applications in regenerative medicine. Nevertheless, these materials are very challenging to monitor in vivo, which has hampered the further development of these materials and their translation into clinical practice. To overcome this limitation, we designed a cross-linked 3D-printable gelatin-based hydrogel endowed with poly[N-(2,2-difluoroethyl)acrylamide] (PDFEA). Such PDFEA-containing hydrogels can be monitored in vivo through fluorine-19 magnetic resonance imaging (F-19 MRI), which enables to monitor such implants in vivo and to assess their in vivo biodegradation kinetics. Herein, we prepared three different PDFEA-containing hydrogels with varying cross-linking degrees and studied their physicochemical properties (storage modulus, Young's modulus, swelling ratio, in vitro degradation rate). Next, we administered these samples subcutaneously into mice and exploited F-19 MRI to detect the biodegradation kinetics over 370 days. Hydrogels with a high cross-linking degree did not extensively degrade in vitro nor in vivo within the evaluated time frame. In contrast, hydrogels characterized by a low degree of cross-linking extensively degraded in vitro as well as in vivo (half-life of 228 +/- 21 days). We demonstrated that endowing hydrogels with PDFEA enables monitoring of these hydrogels in vivo. Our results may become a benchmark in forthcoming studies of biodegradable hydrogels and the development of F-19 MRI detectable gelatin-based hydrogels, paving the way toward their entry in clinical practice.

The permeability and responsiveness of polymer membranes are absolutely relevant in the design of polymersomes for cargo delivery. Accordingly, we herein correlate the structural features, permeability, and responsiveness of doxorubicin-loaded (DOX-loaded) nonresponsive and stimuli-responsive polymersomes with their in vitro and in vivo antitumor performance. Polymer vesicles were produced using amphiphilic block copolymers containing a hydrophilic poly[N-(2-hydroxypropyl)methacrylamide] (PHPMA) segment linked to poly[N-(4-isopropylphenylacetamide)ethyl methacrylate] (PPPhA, nonresponsive block), poly[4-(4,4,5,5-tetra-methyl-1,3,2-dioxaborolan-2-yl)benzyl methacrylate] [PbAPE, reactive oxygen species (ROS)-responsive block], or poly[2-(diisopropylamino)ethyl methacrylate] (PDPA, pH-responsive block). The PDPA-based polymersomes demonstrated outstanding biological performance with antitumor activity notably enhanced compared to their counterparts. We attribute this behavior to a fast-triggered DOX release in acidic tumor environments as induced by pH-responsive polymersome disassembly at pH < 6.8. Possibly, an insufficient ROS concentration in the selected tumor model attenuates the rate of ROS-responsive vesicle degradation, whereas the nonresponsive nature of the PPPhA block remarkably impacts the performance of such potential nanomedicines.

BACKGROUND:Cell cycle progression and leukemia development are tightly regulated processes in which even a small imbalance in the expression of cell cycle regulatory molecules and microRNAs (miRNAs) can lead to an increased risk of cancer/leukemia development. Here, we focus on the study of a ubiquitous, multifunctional, and oncogenic miRNA-hsa-miR-155-5p (miR-155, MIR155HG), which is overexpressed in malignancies including chronic lymphocytic leukemia (CLL). Nonetheless, the precise mechanism of how miR-155 regulates the cell cycle in leukemic cells remains the subject of extensive research. METHODS:We edited the CLL cell line MEC-1 by CRISPR/Cas9 to introduce a short deletion within the MIR155HG gene. To describe changes at the transcriptome and miRNome level in miR-155-deficient cells, we performed mRNA-seq/miRNA-seq and validated changes by qRT-PCR. Flow cytometry was used to measure cell cycle kinetics. A WST-1 assay, hemocytometer, and Annexin V/PI staining assessed cell viability and proliferation. RESULTS:The limited but phenotypically robust miR-155 modification impaired cell proliferation, cell cycle, and cell ploidy. This was accompanied by overexpression of the negative cell cycle regulator p21/CDKN1A and Cyclin D1 (CCND1). We confirmed the overexpression of canonical miR-155 targets such as PU.1, FOS, SHIP-1, TP53INP1 and revealed new potential targets (FCRL5, ISG15, and MX1). CONCLUSIONS:We demonstrate that miR-155 deficiency impairs cell proliferation, cell cycle, transcriptome, and miRNome via deregulation of the MIR155HG/TP53INP1/CDKN1A/CCND1 axis. Our CLL model is valuable for further studies to manipulate miRNA levels to revert highly aggressive leukemic cells to nearly benign or non-leukemic types.

We report the design, synthesis, and in vitro evaluation of stimuli-responsive nanoscale micelles that can be activated by light to induce a cytotoxic effect. Micelles were assembled from amphiphilic units made of a photoactivatable ferrocenyl linker, connected on one side to a lipophilic chain, and on the other side to a hydrophilic pegylated chain. In vitro experiments indicated that pristine micelles ("off" state) were nontoxic to MCF-7 cancer cells, even at high concentrations, but became potent upon photoactivation ("on" state). The illumination process led to the dissociation of the micelles and the concomitant release of iron species, triggering cytotoxicity.

Poly( ɛ -caprolactone) (PCL) is a biocompatible, biodegradable, and highly mechanically resilient FDA-approved material (for specific biomedical applications, e.g. as drug delivery devices, in sutures, or as an adhesion barrier), rendering it a promising candidate to serve bone tissue engineering. However, in vivo monitoring of PCL-based implants, as well as biodegradable implants in general, and their degradation profiles pose a significant challenge, hindering further development in the tissue engineering field and subsequent clinical adoption. To address this, photo-cross-linkable mechanically resilient PCL networks are developed and functionalized with a radiopaque monomer, 5-acrylamido-2,4,6-triiodoisophthalic acid (AATIPA), to enable non-destructive in vivo monitoring of PCL-based implants. The covalent incorporation of AATIPA into the crosslinked PCL networks does not significantly affect their crosslinking kinetics, mechanical properties, or thermal properties, but it increases their hydrolysis rate and radiopacity. Complex and porous 3D designs of radiopaque PCL networks can be effectively monitored in vivo. This work paves the way toward non-invasive monitoring of in vivo degradation profiles and early detection of potential implant malfunctions.

Hyperbaric oxygen therapy (HBOT) proves vital in saving lives by elevating the partial pressure of oxygen (pO2). However, HBOT may also have toxic effects, including lung and retinal damage (peripheral HBOT toxicity), muscle spasms and violent myoclonic convulsions (CNS HBOT toxicity), which may even lead to death if left untreated. Despite the severity of the toxic effects of HBOT, their mechanism is only poorly understood to date. This lack of understanding the underlying mechanism hinders the development of new, effective therapies and preventive strategies to supress HBOT toxicity. Herein, we provide evidence that (1) increased pO2 increases the content of reactive oxygen species (ROS) in tissues, which causes peripheral HBOT toxicity and contributes to CNS toxicity by irreversibly altering cell receptors. Moreover, (2) increased ROS concentration in brain lowers activity of glutamic decarboxylase (GD), which lowers concentrations of inhibitory neurotransmitter gamma-aminobutyric acid (GABA), thereby contributing to the onset of HBOT-derived convulsions. At last, we provide long overlooked evidence that (3) elevated ambient pressure directly inhibits GABA(A) and glycine receptors, thereby leading to the rapid onset of HBOT-derived convulsions. We show that only a combination of these three mechanisms (1 + 2 + 3) are needed to explain most phenomena seen in HBOT toxicity (especially in CNS toxicity). Based on these proposed intertwined mechanisms, we propose administering antioxidants (lowering ROS concentrations), pyridoxine (restoring GD activity), and low doses of sedatives/ anaesthetics (reversing inhibitory effects of pressure on GABA(A) and glycine receptors) before routine hyperbaric oxygen therapies and deep-sea diving to prevent the HBOT toxicity.

Background: Targeted alpha therapy is one of the most powerful therapeutical modalities available in nuclear medicine. It's therapeutic potency is based on the nuclides that emit one or several alpha particles providing strong and highly localized therapeutic effects. However, some of these radionuclides, like e.g. 223Ra or 225Ac decay in cascades, where the radioactive progeny originating from the consecutive alpha-decays may leave the original vector and cause unwanted irradiation of non-target organs. This progeny, even if partially retained in target tissues by internalization processes, typically do not follow the fate of originally targeted radiopharmaceutical and potentially spread over body following their own biodistribution. In this study we aimed to estimate 211Pb/211Bi progeny fate from the 223Ra surface-labelled TiO2 nanoparticles in vitro and the fate of 211Pb in vivo in a mice model. Results: In vitro stability studies have shown significant differences between the release of the mother 223Ra and its progeny (211Pb, 211Bi) in all the biological matrices that have been tested. The lowest released activities were measured in saline, resulting in less than 5 % of released activity for all nuclides. Contrary to that, the highest released activity of 223Ra of up to 10 % within 48 h was observed in 5 % solution of albumin. The released activity of its progeny; the 211Pb and 211Bi was in the range of 20-40 % in this test medium. Significantly higher released activities of 211Pb and 211Bi compared to 223Ra by at least 10 % was observed in each biological medium, except saline, where no significant differences were observed. The in vivo biodistribution studies results in a mice model, show similar pattern, where it was found that even after accumulation of nanoparticles in target tissues, approximately 10 % of 211Pb is continuously released into the blood stream within 24 h, followed by its natural accumulation in kidneys. Conclusion: This study confirms our assumption that the progeny formed in a chain alpha decay of a certain nuclide, in this case the 223Ra, can be released from its original vector, leave the target tissue, relocate and could be deposited in non-target organs. We did not observe complete progeny wash-out from its original target tissues in our model. This indicates strong dependence of the progeny hot atom fate after its release from the original radiopharmaceutical preparation on multiple factors, like their internalization and retention in cells, cell membranes, extracellular matrices, protein binding, etc. We hypothesize, that also the primary tumour or metastasis size, their metabolic activity may significantly influence progeny fate in vivo, directly impacting the dose delivered to non-target tissues and organs. Therefore a bottom -up approach should be followed and detailed pre-/clinical studies on the release and biodistribution of radioactive progeny originating from the chain alpha emitters should be preferably performed.

BACKGROUND:Vascularized lymph node transfer (VLNT) is a relatively well-established microsurgical treatment for lymphedema that is especially beneficial for advanced cases in which lymphovenous anastomosis is not indicated due to lymphatic vessel sclerosis. When VLNT is performed without a skin paddle, such as a buried flap, the possibilities for postoperative monitoring are limited. The aim of our study was to evaluate the use of ultra-high-frequency color Doppler ultrasound with 3D reconstruction in a pedicled axillary lymph node flap.METHODS:Flaps were elevated in 15 Wistar rats based on the lateral thoracic vessels. We preserved the axillary vessels to maintain the rats' mobility and comfort. The rats were divided into three groups as follows: Group A, arterial ischemia; group B, venous occlusion; and group C, healthy.RESULTS:Ultrasound and color Doppler scan images revealed clear information on flap morphology changes and pathology if it was present. Surprisingly, we detected venous flow in group A rats, supporting the pump theory and venous lymph node flap concept.CONCLUSION:We conclude that 3D color Doppler ultrasound is an effective method for monitoring buried lymph node flaps. 3D reconstruction makes it easier to visualize the flap anatomy and detect pathology if it is present. Moreover, the learning curve for the technique is short. Our setup is user-friendly even in the inexperienced hands of a surgical resident, and images can be reevaluated at any time if necessary. The use of 3D reconstruction removes the complications associated with observer-dependent monitoring of VLNT.