Genetically Encoded Reporters to Monitor Hypoxia.

Hypoxia resulting from an imbalance of oxygen availability and consumption defines a metabolic cellular state with a profound impact on developmental processes, tissue maintenance, and the development of pathologies. Fluorescence imaging using genetically encoded reporters enables hypoxia and oxygen imaging with cellular resolution. Thereby unrestricted visualization of hypoxic cells and regions essentially relies on the availability of oxygen-independent fluorescent proteins like UnaG, isolated from the Japanese freshwater eel.

Therapy-induced modulation of tumor vasculature and oxygenation in a murine glioblastoma model quantified by deep learning-based feature extraction.

Glioblastoma presents characteristically with an exuberant, poorly functional vasculature that causes malperfusion, hypoxia and necrosis. Despite limited clinical efficacy, anti-angiogenesis resulting in vascular normalization remains a promising therapeutic approach. Yet, fundamental questions concerning anti-angiogenic therapy remain unanswered, partly due to the scale and resolution gap between microscopy and clinical imaging and a lack of quantitative data readouts.

Genetically encoded dual fluorophore reporters for graded oxygen-sensing in light microscopy.

Hypoxia is an essential regulator of cell metabolism, affects cell migration and angiogenesis during development and contributes to a wide range of pathological conditions. Multiple techniques to assess hypoxia through oxygen-imaging have been developed. However, significant limitations include low spatiotemporal resolution, limited tissue penetration of exogenous probes and non-dynamic signals due to irreversible probe-chemistry.

Preclinical Evaluation of Ga- and Lu-Labeled Integrin αβ-Targeting Radiotheranostic Peptides.

The integrin αβ, an epithelium-specific cell surface receptor, is overexpressed on numerous malignancies, including the highly lethal pancreatic ductal adenocarcinomas. Here, we developed and tested a novel αβ-targeting peptide, DOTA-5G () radiolabeled with Ga, for PET/CT imaging and Lu for treatment. With the goal to develop a radiotheranostic, further modifications were made for increased circulation time, renal recycling, and tumor uptake, yielding DOTA-albumin-binding moiety-5G ().

Phenanthroindolizidine Alkaloids Isolated from as Potent Inhibitors of Inflammation, Spheroid Growth, and Invasion of Triple-Negative Breast Cancer.

Triple-negative breast cancer (TNBC), representing the most aggressive form of breast cancer with currently no targeted therapy available, is characterized by an inflammatory and hypoxic tumor microenvironment. To date, a broad spectrum of anti-tumor activities has been reported for phenanthroindolizidine alkaloids (PAs), however, their mode of action in TNBC remains elusive. Thus, we investigated six naturally occurring PAs extracted from the plant : -methyltylophorinidine () and its five derivatives tylophorinidine (), tylophoridicine E (), 2-demethoxytylophorine (), tylophoridicine D (), and anhydrodehydrotylophorinidine ().

Volumetric imaging reveals VEGF-C-dependent formation of hepatic lymph vessels in mice.

The liver is a major biosynthetic and detoxifying organ in vertebrates, but also generates 25%-50% of the lymph passing through the thoracic duct and is thereby the organ with the highest contribution to lymph flow. In contrast to its metabolic function, the role of the liver for lymph generation and composition is presently severely understudied. We took a rigorous, volume imaging-based approach to describe the microarchitecture and spatial composition of the hepatic lymphatic vasculature with cellular resolution in whole mount immune stained specimen ranging from thick sections up to entire mouse liver lobes.

Evaluation of Copper-64-Labeled αβ-Targeting Peptides: Addition of an Albumin Binding Moiety to Improve Pharmacokinetics.

The incorporation of non-covalent albumin binding moieties (ABMs) into radiotracers results in increased circulation time, leading to a higher uptake in the target tissues such as the tumor, and, in some cases, reduced kidney retention. We previously developed [F]AlF NOTA-K(ABM)-αβ-BP, where αβ-BP is a peptide with high affinity for the cell surface receptor integrin αβ that is overexpressed in several cancers, and the ABM is an iodophenyl-based moiety. [F]AlF NOTA-K(ABM)-αβ-BP demonstrated prolonged blood circulation compared to the non-ABM parent peptide, resulting in high, αβ-targeted uptake with continuously improving detection of αβ(+) tumors using PET/CT.

The Effects of an Albumin Binding Moiety on the Targeting and Pharmacokinetics of an Integrin αβ-Selective Peptide Labeled with Aluminum [F]Fluoride.

Purpose: The αβ-BP peptide selectively targets the integrin αβ, a cell surface receptor recognized as a prognostic indicator for several challenging malignancies. Given that the 4-[F]fluorobenzoyl (FBA)-labeled peptide is a promising PET imaging agent, radiolabeling via aluminum [F]fluoride chelation and introduction of an albumin binding moiety (ABM) have the potential to considerably simplify radiochemistry and improve the pharmacokinetics by increasing biological half-life.

Procedures: The peptides NOTA-αβ-BP (1) and NOTA-K(ABM)-αβ-BP (2) were synthesized on solid phase, radiolabeled with aluminum [F]fluoride, and evaluated in vitro (integrin ELISA, albumin binding, cell studies) and in vivo in mouse models bearing paired DX3puroβ6 [αβ(+)]/DX3puro [αβ(-)], and for [F]AlF 2, BxPC-3 [αβ(+)] cell xenografts (PET imaging, biodistribution).

Correction to: Evaluation of Two Optical Probes for Imaging the Integrin αvβ6- In Vitro and In Vivo in Tumor-Bearing Mice.

This article was updated to correct the axes in Figures 4e and 5d.

Evaluation of Two Optical Probes for Imaging the Integrin αβ- In Vitro and In Vivo in Tumor-Bearing Mice.

Purpose: The purpose of this study was to develop and evaluate two αβ-targeted fluorescent imaging agents. The integrin subtype αβ is significantly upregulated in a wide range of epithelial derived cancers, plays a key role in invasion and metastasis, and expression is often located at the invasive edge of tumors. αβ-targeted fluorescent imaging agents have the potential to guide surgical resection leading to improved patient outcomes.

Brain penetrant small molecule (18)F-GnRH receptor (GnRH-R) antagonists: Synthesis and preliminary positron emission tomography imaging in rats.

Introduction: The gonadotropin releasing hormone receptor (GnRH-R) has a well-described neuroendocrine function in the anterior pituitary. However, little is known about its function in the central nervous system (CNS), where it is most abundantly expressed in hippocampus and amygdala. Since peptide ligands based upon the endogenous decapetide GnRH do not pass the blood-brain-barrier, we are seeking a high-affinity small molecule GnRH-R ligand suitable for brain imaging by positron emission tomography.

The Effect of Bi-Terminal PEGylation of an Integrin αvβ₆-Targeted ¹⁸F Peptide on Pharmacokinetics and Tumor Uptake.

Unlabelled: Radiotracers based on the peptide A20FMDV2 selectively target the cell surface receptor integrin αvβ6. This integrin has been identified as a prognostic indicator correlating with the severity of disease for several challenging malignancies. In previous studies of A20FMDV2 peptides labeled with 4-(18)F-fluorobenzoic acid ((18)F-FBA), we have shown that the introduction of poly(ethylene glycol) (PEG) improves pharmacokinetics, including increased uptake in αvβ6-expressing tumors.

In vivo optical imaging of matrix metalloproteinase activity detects acute and chronic contact hypersensitivity reactions and enables monitoring of the antiinflammatory effects of N-acetylcysteine.

The aim of this study was to determine whether the severity of contact hypersensitivity reactions (CHSRs) can be observed by noninvasive in vivo optical imaging of matrix metalloproteinase (MMP) activity and whether this is an appropriate tool for monitoring an antiinflammatory effect. Acute and chronic CHSRs were elicited by application of a 1% trinitrochlorobenzene (TNCB) solution for up to five times on the right ear of TNCB-sensitized mice. N-Acetylcysteine (NAC)-treated and sham-treated mice were monitored by measuring ear swelling and optical imaging of MMP activity.

Cerenkov luminescence imaging of αv β6 integrin expressing tumors using (90) Y-labeled peptides.

Cerenkov luminescence imaging (CLI) is an emerging preclinical molecular imaging modality that tracks the radiation emitted in the visible spectrum by fast moving charged decay products of radionuclides. The aim of this study was in vitro and in vivo evaluation of the two radiotracers, (90) Y-DOTA-PEG28 -A20FMDV2 ((90) Y-1) and (90) Y-DOTA-Ahx-A20FMDV2 ((90) Y-2) (>99% radiochemical purity, 3.7 GBq/µmol specific activity) for noninvasive assessment of tumors expressing the integrin αv β6 and their future use in tumor targeted radiotherapy.

Characterization and evaluation of (64)Cu-labeled A20FMDV2 conjugates for imaging the integrin αvβ 6.

Purpose: The integrin αvβ6 is overexpressed in a variety of aggressive cancers and serves as a prognosis marker. This study describes the conjugation, radiolabeling, and in vitro and in vivo evaluation of four chelators to determine the best candidate for (64)Cu radiolabeling of A20FMDV2, an αvβ6 targeting peptide.

Procedures: Four chelators were conjugated onto PEG28-A20FMDV2 (1): 11-carboxymethyl-1,4,8,11-tetraazabicyclo[6.

In vitro and in vivo evaluation of the effects of aluminum [¹⁸F]fluoride radiolabeling on an integrin αvβ₆-specific peptide.

Introduction: Incorporation of fluorine-18 ((18)F) into radiotracers by capturing ionic [(18)F]-species can greatly accelerate and simplify radiolabeling for this important positron emission tomography (PET) radioisotope. Among the different strategies, the incorporation of aluminum [(18)F]fluoride (Al[(18)F](2+)) into NOTA chelators has recently emerged as a robust approach to peptide radiolabeling. This study presents Al[(18)F](2+)-radiolabeling of an α(v)β₆ integrin-targeted peptide (NOTA-PEG₂₈-A20FMDV2) and its in vitro and in vivo evaluation.

Evaluation of an integrin αvβ6-specific peptide labeled with [18F]fluorine by copper-free, strain-promoted click chemistry.

Introduction: Click chemistry, particularly the Huisgen 1,3-dipolar cycloaddition of an alkyne with an azide, has quickly become popular for site-specific radiolabeling. Recently, strain-promoted click chemistries have been developed, eliminating the need for potentially toxic copper catalysts. This study presents radiolabeling of an α(v)β(6) integrin targeting peptide (A20FMDV2) via strain-promoted click using a fluorine-18 prosthetic group, and in vitro and in vivo evaluation.

TRANSFORMATION AND ALLELOPATHY OF NATURAL DISSOLVED ORGANIC CARBON AND TANNIC ACID ARE AFFECTED BY SOLAR RADIATION AND BACTERIA(1).

The aim of this study was to test whether abiotic and biotic factors may affect allelopathic properties. Therefore, we investigated how solar radiation and bacteria influence allelopathic effects of the plant-derived, polyphenolic tannic acid (TA) on microalgae. Using a block design, lake water samples with and without TA were exposed to solar radiation or kept in darkness with or without bacteria for 3 weeks.

COMPARISON OF METHODS TO DETECT ALLELOPATHIC EFFECTS OF SUBMERGED MACROPHYTES ON GREEN ALGAE(1).

Detecting allelopathic inhibition of phytoplankton by submerged macrophytes in an ecologically meaningful way is not easy. Multiple-approach investigations from a laboratory scale to the ecosystem level have been recommended to overcome the shortcomings of individual methods. Whether results of different methods are qualitatively or quantitatively comparable has not yet been tested.

The course of genetically determined chronic pancreatitis.

Context: The clinical course of chronic pancreatitis in patients with mutations of cationic trypsinogen and the trypsin inhibitor SPINK1 has not yet been characterized.

Setting: Cationic trypsinogen (PRSS1) and the serine protease inhibitor, Kazal type 1 (SPINK1), were analyzed in patients with pancreatitis of unclear origin.

Patients: Eighty subjects with trypsinogen mutations (21x N29I, 59x R122H) and 59 patients with the SPINK1 N34S variant (11 homozygous, 48 heterozygous) were included in the study.

Mutational screening of patients with nonalcoholic chronic pancreatitis: identification of further trypsinogen variants.

Objectives: Mutations of the cationic trypsinogen (CT) and the serine protease inhibitor, Kazal type 1 (SPINK 1) are associated with chronic pancreatitis. After mutational screening of a cohort of patients with nonalcoholic chronic pancreatitis, we report three novel variants of the trypsinogen molecule and the clinical characteristics of the carriers.

Methods: The coding region of the exon 2 and 3 of the CT gene of 523 patients with chronic nonalcoholic pancreatitis (108 patients with suspected hereditary pancreatitis (HP) and 415 patients with "idio pathic" pancreatitis [IP]) and 82 controls was analyzed after polymerase chain reaction amplification.