Short-wave infrared fluorescence imaging of near-infrared dyes with robust end-tail emission using a small-animal imaging device.

Commercially available near-infrared (NIR) dyes, including indocyanine green (ICG), display an end-tail of the fluorescence emission spectrum detectable in the short-wave infrared (SWIR) window. Imaging methods based on the second NIR spectral region (1,000-1,700 nm) are gaining interest within the biomedical imaging community due to minimal autofluorescence and scattering, allowing higher spatial resolution and depth sensitivity. Using a SWIR fluorescence imaging device, the properties of ICG vs. heptamethine cyanine dyes with emission >800 nm were evaluated using tissue-simulating phantoms and animal experiments. In this study, we tested the hypothesis that an increased rigidity of the heptamethine chain may increase the SWIR imaging performance due to the bathochromic shift of the emission spectrum. Fluorescence SWIR imaging of capillary plastic tubes filled with dyes was followed by experiments on healthy animals in which a time series of fluorescence hindlimb images were analyzed. Our findings suggest that higher spatial resolution can be achieved even at greater depths (>5 mm) or longer wavelengths (>1,100 nm), in both tissue phantoms and animals, opening the possibility to translate the SWIR prototype toward clinical application.

Structure Elucidation of Aroma-Active Bicyclic Benzofuran Derivatives Formed by Cystostereum murrayi.

Among the monoterpenoid aroma compounds formed by the basidiomycete Cystostereum murrayi are highly potent bicyclic benzofuran derivatives. In addition to the dill ethers previously described in a few fungi, two stereoisomers of the rare 3,6-dimethyl-3a,4,5,6,7,7a-hexahydro-3H-1-benzofuran-2-one (1a and 2c), also known as dihydromenthofurolactones, and a C3-unsaturated analogue (3a) are formed by C. murrayi. The analysis of synthesized reference standards of the lactones allowed an unambiguous assignment of the stereoisomers formed by the fungus. Despite a similar structure, two key differences in the stereochemistry of the lactones and dill ethers emerged. The analysis of submerged cultures further revealed the formation of additional, so far unknown, fungal terpenoids, including limonen-10-ol (7) and the corresponding aldehyde limonen-10-al (8). Analysis of chiral terpenoids as well as supplementation studies, including stable isotope-labeled compounds, indicated independent biogenesis pathways for dill ethers and lactones.

LYN kinase programs stromal fibroblasts to facilitate leukemic survival via regulation of c-JUN and THBS1.

Microenvironmental bystander cells are essential for the progression of chronic lymphocytic leukemia (CLL). We have discovered previously that LYN kinase promotes the formation of a microenvironmental niche for CLL. Here we provide mechanistic evidence that LYN regulates the polarization of stromal fibroblasts to support leukemic progression. LYN is overexpressed in fibroblasts of lymph nodes of CLL patients. LYN-deficient stromal cells reduce CLL growth in vivo. LYN-deficient fibroblasts show markedly reduced leukemia feeding capacity in vitro. Multi-omics profiling reveals that LYN regulates the polarization of fibroblasts towards an inflammatory cancer-associated phenotype through modulation of cytokine secretion and extracellular matrix composition. Mechanistically, LYN deletion reduces inflammatory signaling including reduction of c-JUN expression, which in turn augments the expression of Thrombospondin-1, which binds to CD47 thereby impairing CLL viability. Together, our findings suggest that LYN is essential for rewiring fibroblasts towards a leukemia-supportive phenotype.

CagA-specific Gastric CD8+ Tissue-Resident T Cells Control Helicobacter pylori During the Early Infection Phase.

BACKGROUND & AIMS: Infection with Helicobacter pylori strongly affects global health by causing chronic gastritis, ulcer disease, and gastric cancer. Although extensive research into the strong immune response against this persistently colonizing bacterium exists, the specific role of CD8+ T cells remains elusive. METHODS: We comprehensively characterize gastric H pylori-specific CD8+ T-cell responses in mice and humans by flow cytometry, RNA-sequencing, immunohistochemistry, and ChipCytometry, applying functional analyses including T-cell depletion, H pylori eradication, and ex vivo restimulation. RESULTS: We define CD8+ T-cell populations bearing a tissue-resident memory (TRM) phenotype, which infiltrate the gastric mucosa shortly after infection and mediate pathogen control by executing antigen-specific effector properties. These induced CD8+ tissue-resident memory T cells (TRM cells) show a skewed T-cell receptor beta chain usage and are mostly specific for cytotoxin-associated gene A, the distinctive oncoprotein injected by H pylori into host cells. As the infection progresses, we observe a loss of the TRM phenotype and replacement of CD8+ by CD4+ T cells, indicating a shift in the immune response during the chronic infection phase. CONCLUSIONS: Our results point toward a hitherto unknown role of CD8+ T-cell response in this bacterial infection, which may have important clinical implications for treatment and vaccination strategies against H pylori.

Preclinical Testing of Boron-Doped Diamond Electrodes for Root Canal Disinfection-A Series of Preliminary Studies.

While numerous approaches have meanwhile been described, sufficient disinfection of root canals is still challenging, mostly due to limited access and the porous structure of dentin. Instead of using different rinsing solutions and activated irrigation, the electrolysis of saline using boron-doped diamond (BDD) electrodes thereby producing reactive oxygen species may be an alternative approach. In a first step, experiments using extracted human teeth incubated with multispecies bacterial biofilm were conducted. The charge quantities required for electrochemical disinfection of root canals were determined, which were subsequently applied in an animal trial using an intraoral canine model. It could be shown that also under realistic clinical conditions, predictable disinfection of root canals could be achieved using BDD electrodes. The parameters required are in the range of 5.5 to 7.0 V and 9 to 38 mA, applied for 2.5 to 6.0 min with approximately 5 to 8 mL of saline. The direct generation of disinfective agents inside the root canal seems to be advantageous especially in situations with compromised access and limited canal sizes. The biologic effect with respect to the host reaction on BDD-mediated disinfection is yet to be examined.

Extracellular vesicles and PD-L1 suppress macrophages, inducing therapy resistance in TP53-deficient B-cell malignancies.

Genetic alterations in the DNA damage response (DDR) pathway are a frequent mechanism of resistance to chemoimmunotherapy (CIT) in B-cell malignancies. We have previously shown that the synergy of CIT relies on secretory crosstalk elicited by chemotherapy between the tumor cells and macrophages. Here, we show that loss of multiple different members of the DDR pathway inhibits macrophage phagocytic capacity in vitro and in vivo. Particularly, loss of TP53 led to decreased phagocytic capacity ex vivo across multiple B-cell malignancies. We demonstrate via in vivo cyclophosphamide treatment using the Eµ-TCL1 mouse model that loss of macrophage phagocytic capacity in Tp53-deleted leukemia is driven by a significant downregulation of a phagocytic transcriptomic signature using small conditional RNA sequencing. By analyzing the tumor B-cell proteome, we identified a TP53-specific upregulation of proteins associated with extracellular vesicles (EVs). We abrogated EV biogenesis in tumor B-cells via clustered regularly interspaced short palindromic repeats (CRISPR)-knockout (KO) of RAB27A and confirmed that the EVs from TP53-deleted lymphoma cells were responsible for the reduced phagocytic capacity and the in vivo CIT resistance. Furthermore, we observed that TP53 loss led to an upregulation of both PD-L1 cell surface expression and secretion of EVs by lymphoma cells. Disruption of EV bound PD-L1 by anti-PD-L1 antibodies or PD-L1 CRISPR-KO improved macrophage phagocytic capacity and in vivo therapy response. Thus, we demonstrate enhanced EV release and increased PD-L1 expression in TP53-deficient B-cell lymphomas as novel mechanisms of macrophage function alteration in CIT resistance. This study indicates the use of checkpoint inhibition in the combination treatment of B-cell malignancies with TP53 loss.

Production of an Anise- and Woodruff-like Aroma by Monokaryotic Strains of Pleurotus sapidus Grown on Citrus Side Streams.

The production of natural flavors by means of microorganisms is of great interest for the food and flavor industry, and by-products of the agro-industry are particularly suitable as substrates. In the present study, Citrus side streams were fermented using monokaryotic strains of the fungus Pleurotus sapidus. Some of the cultures exhibited a pleasant smell, reminiscent of woodruff and anise, as well as herbaceous notes. To evaluate the composition of the overall aroma, liquid/liquid extracts of submerged cultures of a selected monokaryon were prepared, and the volatiles were isolated via solvent-assisted flavor evaporation. Aroma extract dilution analyses revealed p-anisaldehyde (sweetish, anisic- and woodruff-like) with a flavor dilution factor of 218 as a character impact compound. The coconut-like, herbaceous, and sweetish smelling acyloin identified as (2S)-hydroxy-1-(4-methoxyphenyl)-1-propanone also contributed to the overall aroma and was described as an aroma-active substance with an odor threshold in air of 0.2 ng L-1 to 2.4 ng L-1 for the first time. Supplementation of the culture medium with isotopically substituted l-tyrosine elucidated this phenolic amino acid as precursor of p-anisaldehyde as well as of (2S)-hydroxy-1-(4-methoxyphenyl)-1-propanone. Chiral analysis via HPLC revealed an enantiomeric excess of 97% for the isolated product produced by P. sapidus.

ITIH5-Derived Polypeptides Covering the VIT Domain Suppress the Growth of Human Cancer Cells In Vitro.

Oncogenic drivers such as mutated EGFR are the preferred targets in modern drug development. However, restoring the lost function of tumor suppressor proteins could also be a valid approach to combatting cancer. ITIH5 has been revealed as a potent metastasis suppressor in both breast and pancreatic cancer. Here, we show that ITIH5 overexpression in MDA-MB-231 breast cancer cells can also locally suppress tumor growth by 85%, when transplanted into the mammary fat pad of nude mice. For a potential drug development approach, we further aimed to define downsized ITIH5 polypeptides that still are capable of mediating growth inhibitory effects. By cloning truncated and His-tagged ITIH5 fragments, we synthesized two recombinant N-terminal polypeptides (ITIH5681aa and ITIH5161aa), both covering the ITI heavy chain specific "vault protein inter-alpha-trypsin" (VIT) domain. Truncated ITIH5 variants caused dose-dependent cell growth inhibition by up to 50% when applied to various cancer cell lines (e.g., MDA-MB-231, SCaBER, A549) reflecting breast, bladder and lung cancer in vitro. Thus, our data suggest the substantial role of the ITIH5-specific VIT domain in ITIH5-mediated suppression of tumor cell proliferation. As extracellularly administered ITIH5 peptides mimic the growth-inhibitory effects of the full-length ITIH5 tumor suppressor protein, they may constitute the basis for developing anticancer drugs in the future.

Gasdermin D mediates host cell death but not interleukin-1ß secretion in Mycobacterium tuberculosis-infected macrophages.

Necrotic cell death represents a major pathogenic mechanism of Mycobacterium tuberculosis (Mtb) infection. It is increasingly evident that Mtb induces several types of regulated necrosis but how these are interconnected and linked to the release of pro-inflammatory cytokines remains unknown. Exploiting a clinical cohort of tuberculosis patients, we show here that the number and size of necrotic lesions correlates with IL-1ß plasma levels as a strong indicator of inflammasome activation. Our mechanistic studies reveal that Mtb triggers mitochondrial permeability transition (mPT) and subsequently extensive macrophage necrosis, which requires activation of the NLRP3 inflammasome. NLRP3-driven mitochondrial damage is dependent on proteolytic activation of the pore-forming effector protein gasdermin D (GSDMD), which links two distinct cell death machineries. Intriguingly, GSDMD, but not the membranolytic mycobacterial ESX-1 secretion system, is dispensable for IL-1ß secretion from Mtb-infected macrophages. Thus, our study dissects a novel mechanism of pathogen-induced regulated necrosis by identifying mitochondria as central regulatory hubs capable of delineating cytokine secretion and lytic cell death.

Bioavailability and -accessibility of subsoil allocated 33P-labelled hydroxyapatite to wheat under different moisture supply.

Information on the bioavailability and -accessibility of subsoil phosphorus (P) and how soil moisture affects its utilization by plants is scarce. The current study examined whether and to which degree wheat acquires P from subsoil allocated hydroxyapatite and how this could be affected by soil moisture. We investigated the 33P uptake by growing wheat in two rhizotron trials (soil and sand) with integrated 33P-labelled hydroxyapatite hotspots over a period of 44 days using digital autoradiography imaging and liquid scintillation counting. We applied two irrigation scenarios, mimicking either rainfall via topsoil watering or subsoil water storage. The plants showed similar biomass development when grown in soil, but a reduced growth in sand rhizotrons. Total plant P(tot) stocks were significantly larger in plants grown under improved subsoil moisture supply, further evidenced by enhanced P stocks in the ears of wheat in the sand treatment due to an earlier grain filling. This P uptake is accompanied by larger 33P signals, indicating that the plants accessed the hydroxyapatite because subsoil irrigation also promoted root proliferation within and around the hotspots. We conclude that even within a single season plants access subsoil mineral P sources, and this process is influenced by water management.

Pilot Study on the Use of a Laser-Structured Double Diamond Electrode (DDE) for Biofilm Removal from Dental Implant Surfaces.

No proper treatment option for peri-implantitis exists yet. Based on previous studies showing the in vitro effectiveness of electrochemical disinfection using boron-doped diamond electrodes, novel double diamond electrodes (DDE) were tested here. Using a ceramic carrier and a laser structuring process, a clinically applicable electrode array was manufactured. Roughened metal discs (n = 24) made from Ti-Zr alloy were exposed to the oral cavities of six volunteers for 24 h in order to generate biofilm. Then, biofilm removal was carried out either using plastic curettes and chlorhexidine digluconate or electrochemical disinfection. In addition, dental implants were contaminated with ex vivo multispecies biofilm and disinfected using DDE treatment. Bacterial growth and the formation of biofilm polymer were determined as outcome measures. Chemo-mechanical treatment could not eliminate bacteria from roughened surfaces, while in most cases, a massive reduction of bacteria and biofilm polymer was observed following DDE treatment. Electrochemical disinfection was charge- and time-dependent and could also not reach complete disinfection in all instances. Implant threads had no negative effect on DDE treatment. Bacteria exhibit varying resistance to electrochemical disinfection with Bacillus subtilis, Neisseria sp., Rothiamucilaginosa, Staphylococcus haemolyticus, and Streptococcus mitis surviving 5 min of DDE application at 6 V. Electrochemical disinfection is promising but requires further optimization with respect to charge quantity and application time in order to achieve disinfection without harming host tissue.

Meta-Analysis Reveals Significant Sex Differences in Chronic Lymphocytic Leukemia Progression in the Eµ-TCL1 Transgenic Mouse Model.

The Eµ-TCL1 transgenic mouse model represents the most widely and extensively used animal model for chronic lymphocytic leukemia (CLL). In this report, we performed a meta-analysis of leukemia progression in over 300 individual Eµ-TCL1 transgenic mice and discovered a significantly accelerated disease progression in females compared to males. This difference is also reflected in an aggressive CLL mouse model with additional deletion of Tp53 besides the TCL1 transgene. Moreover, after serial adoptive transplantation of murine CLL cells, female recipients also succumbed to CLL earlier than male recipients. This sex-related disparity in the murine models is markedly contradictory to the human CLL condition. Thus, due to our observation we urge both careful consideration in the experimental design and accurate description of the Eµ-TCL1 transgenic cohorts in future studies.

ITIH5 and ECRG4 DNA Methylation Biomarker Test (EI-BLA) for Urine-Based Non-Invasive Detection of Bladder Cancer.

Bladder cancer is one of the more common malignancies in humans and the most expensive tumor for treating in the Unites States (US) and Europe due to the need for lifelong surveillance. Non-invasive tests approved by the FDA have not been widely adopted in routine diagnosis so far. Therefore, we aimed to characterize the two putative tumor suppressor genes ECRG4 and ITIH5 as novel urinary DNA methylation biomarkers that are suitable for non-invasive detection of bladder cancer. While assessing the analytical performance, a spiking experiment was performed by determining the limit of RT112 tumor cell detection (range: 100-10,000 cells) in the urine of healthy donors in dependency of the processing protocols of the RWTH cBMB. Clinically, urine sediments of 474 patients were analyzed by using quantitative methylation-specific PCR (qMSP) and Methylation Sensitive Restriction Enzyme (MSRE) qPCR techniques. Overall, ECRG4-ITIH5 showed a sensitivity of 64% to 70% with a specificity ranging between 80% and 92%, i.e., discriminating healthy, benign lesions, and/or inflammatory diseases from bladder tumors. When comparing single biomarkers, ECRG4 achieved a sensitivity of 73%, which was increased by combination with the known biomarker candidate NID2 up to 76% at a specificity of 97%. Hence, ITIH5 and, in particular, ECRG4 might be promising candidates for further optimizing current bladder cancer biomarker panels and platforms.

Electrochemical Disinfection of Dental Implants Experimentally Contaminated with Microorganisms as a Model for Periimplantitis.

Despite several methods having been described for disinfecting implants affected by periimplantitis, none of these are universally effective and may even alter surfaces and mechanical properties of implants. Boron-doped diamond (BDD) electrodes were fabricated from niobium wires and assembled as a single instrument for implant cleaning. Chemo-mechanical debridement and air abrasion were used as control methods. Different mono-species biofilms, formed by bacteria and yeasts, were allowed to develop in rich medium at 37 °C for three days. In addition, natural multi-species biofilms were treated. Implants were placed in silicone, polyurethane foam and bovine ribs for simulating different clinical conditions. Following treatment, the implants were rolled on blood agar plates, which were subsequently incubated at 37 °C and microbial growth was analyzed. Complete electrochemical disinfection of implant surfaces was achieved with a maximum treatment time of 20 min for Candida albicans, Candida dubliniensis, Enterococcus faecalis, Roseomonas mucosa, Staphylococcus epidermidis and Streptococcus sanguinis, while in case of spore-forming Bacillus pumilus and Bacillus subtilis, a number of colonies appeared after BDD electrode treatment indicating an incomplete disinfection. Independent of the species tested, complete disinfection was never achieved when conventional techniques were used. During treatment with BDD electrodes, only minor changes in temperature and pH value were observed. The instrument used here requires optimization so that higher charge quantities can be applied in shorter treatment times.

Multi-Parametric Standardization of Fluorescence Imaging Systems Based on a Composite Phantom.

OBJECTIVE: Fluorescence molecular imaging (FMI) has emerged as a promising tool for surgical guidance in oncology, with one of the few remaining challenges being the ability to offer quality control and data referencing. This paper investigates the use of a novel composite phantom to correct and benchmark FMI systems. METHODS: This paper extends on previous work by describing a phantom design that can provide a more complete assessment of FMI systems through quantification of dynamic range and determination of spatial illumination patterns for both reflectance and fluorescence imaging. Various performance metrics are combined into a robust and descriptive "system benchmarking score," enabling not only the comprehensive comparison of different systems, but also for the first time, correction of the acquired data. RESULTS: We show that systems developed for targeted fluorescence imaging can achieve benchmarking scores of up to 70%, while clinically available systems optimized for indocyanine green are limited to 50%, mostly due to greater leakage of ambient and excitation illumination and lower resolution. The image uniformity can also be approximated and employed for image flat-fielding, an important milestone toward data referencing. In addition, we demonstrate composite phantom use in assessing the performance of a surgical microscope and of a raster-scan imaging system. CONCLUSION: Our results suggest that the new phantom has the potential to support high-fidelity FMI through benchmarking and image correction. SIGNIFICANCE: Standardization of the FMI is a necessary process for establishing good imaging practices in clinical environments and for enabling high-fidelity imaging across patients and multi-center imaging studies.

Land use change from permanent rice to alternating rice-shrimp or permanent shrimp in the coastal Mekong Delta, Vietnam: Changes in the nutrient status and binding forms.

Saline water intrusion has become a severe threat in the coastal areas of Mekong delta of Vietnam, though offering farmers the option to diversify their land use, and switching, for instance, from permanent rice to alternating rice-shrimp systems or even to permanent shrimp systems. The objective of this study was to evaluate the respective impacts on soil salinity, nutrient status and their binding forms. Hence, we sampled the topsoils (cultivation layer, 0-15 cm) from 10 permanent rice systems and the rice platforms of 10 alternating riceshrimp systems. Furthermore, the sludges and the soils 10 cm underneath of the sludges from the ditches of the alternating rice-shrimp as well as from ponds of the permanent shrimp systems were sampled in Ben Tre and Sóc Trang provinces, Vietnam, respectively. The samples were analyzed regarding their electric conductivity, total and plant-available nutrient contents. To reveal possible changes in nutrient binding forms, sequential P and S extraction, 31P-nuclear magnetic resonance spectroscopy, and S and P X-ray absorption near edge structure spectroscopy were applied. The results showed that permanent and alternating shrimp cultivation lead to elevated salt concentrations but also improved the overall nutrient status relative to the permanent rice management and especially in the sludges relative to the soils underneath. The continued deposition of shrimp and feed debris promoted the accrual of stable, Ca- and Mg-associated P forms as well as of P-monoesters, whereas the S forms were depleted in thiophene S groups but enriched in sulfides relative to permanent rice fields. As effects by alternating rice-shrimp management were intermediate, this management has more potential to serve as a no-regret strategy for farmers to remain flexible in their response to climate changes and concurrent salinity intrusion relative to permanent shrimp production, which requires strict maintenance of adequate salinity levels also during the rainy season.

Influence of In-Situ Electrochemical Oxidation on Implant Surface and Colonizing Microorganisms Evaluated by Scanning Electron Microscopy.

Peri-implantitis is a worldwide increasing health problem, caused by infection of tissue and bone around an implant by biofilm-forming microorganisms. Effects of peri-implantitis treatment using mechanical debridement, air particle abrasion and electrochemical disinfection on implant surface integrity were compared. Dental implants covered with bacterial biofilm were cleaned using mechanical debridement and air particle abrasion. In addition, implants were disinfected using a novel electrochemical technique based on an array of boron-doped diamond (BDD) coated electrodes. Following treatment and preparation, the implants were inspected by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). Mechanical debridement led to changes in surface topography destroying the manufacturer's medium-rough surface by scratch formation. Air particle abrasion led to accumulation of the abrasive used on the implant surface. With both treatment options, appearance of bacteria and yeasts was not affected. In contrast, electrochemical disinfection did not cause alterations of the implant surface but resulted in distorted microbial cells. Electrochemical disinfection of implant surfaces using BDD electrodes may constitute a promising treatment option for cleaning dental implant surfaces without negatively affecting materials and surface properties.

Fluorescence imaging reversion using spatially variant deconvolution.

Fluorescence imaging opens new possibilities for intraoperative guidance and early cancer detection, in particular when using agents that target specific disease features. Nevertheless, photon scattering in tissue degrades image quality and leads to ambiguity in fluorescence image interpretation and challenges clinical translation. We introduce the concept of capturing the spatially-dependent impulse response of an image and investigate Spatially Adaptive Impulse Response Correction (SAIRC), a method that is proposed for improving the accuracy and sensitivity achieved. Unlike classical methods that presume a homogeneous spatial distribution of optical properties in tissue, SAIRC explicitly measures the optical heterogeneity in tissues. This information allows, for the first time, the application of spatially-dependent deconvolution to correct the fluorescence images captured in relation to their modification by photon scatter. Using experimental measurements from phantoms and animals, we investigate the improvement in resolution and quantification over non-corrected images. We discuss how the proposed method is essential for maximizing the performance of fluorescence molecular imaging in the clinic.

Electrochemical Disinfection of Experimentally Infected Teeth by Boron-Doped Diamond Electrode Treatment.

Disinfection and prevention of re-infection are the decisive treatment steps in endodontic therapy. In this study, boron-doped diamond (BDD) electrodes have been fabricated and used for disinfecting the root canals of extracted human teeth, which had been covered with bacterial biofilms formed by Bacillus subtilis and Staphylococcus epidermidis. The growth of B. subtilis could be successfully impaired, achieving a complete disinfection after 8.5 min treatment time with the success of disinfection depending on the insertion depth of the electrode in the root canal. S. epidermidis could completely be removed after 3.5 min treatment time. A clinically applicable electrode array led to complete disinfection after treatment times of 10 min for S. epidermidis and 25 min for B. subtilis. BDD electrode application allowed for the improved disinfection of root canals and dentin tubules based on a continuous production of reactive oxygen species and their enhanced penetration of dentin tubules most likely due the formation of a continuous stream of small gas bubbles. The treatment times that are required here will be shortened in clinical application, as mechanical shaping of the canal system would precede the disinfection process.

Quantitative imaging of 33P in plant materials using 14C polymer references.

Phosphorus (P) research still lacks techniques for rapid imaging of P use and allocation in different soil, sediment, and biological systems in a quantitative manner. In this study, we describe a time-saving and cost-efficient digital autoradiographic method for in situ quantitative imaging of 33P radioisotopes in plant materials. Our method combines autoradiography of the radiotracer applications with additions of commercially available 14C polymer references to obtain 33P activities in a quantitative manner up to 2000 Bq cm-2. Our data show that linear standard regressions for both radioisotopes are obtained, allowing the establishment of photostimulated luminescence equivalence between both radioisotopes with a factor of 9.73. Validating experiments revealed a good agreement between the calculated and applied 33P activity (R2 = 0.96). This finding was also valid for the co-exposure of 14C polymer references and 33P radioisotope specific activities in excised plant leaves for both maize (R2 = 0.99) and wheat (R2 = 0.99). The outlined autoradiographic quantification procedure retrieved 100% ± 12% of the 33P activity in the plant leaves, irrespective of plant tissue density. The simplicity of this methodology opens up new perspectives for fast quantitative imaging of 33P in biological systems and likely, thus, also for other environmental compartments.