Assessment of a Plasma Amyloid Probability Score to Estimate Amyloid Positron Emission Tomography Findings Among Adults With Cognitive Impairment.

Importance: The diagnostic evaluation for Alzheimer disease may be improved by a blood-based diagnostic test identifying presence of brain amyloid plaque pathology.

Objective: To determine the clinical performance associated with a diagnostic algorithm incorporating plasma amyloid-β (Aβ) 42:40 ratio, patient age, and apoE proteotype to identify brain amyloid status.

Design, Setting, And Participants: This cohort study includes analysis from 2 independent cross-sectional cohort studies: the discovery cohort of the Plasma Test for Amyloidosis Risk Screening (PARIS) study, a prospective add-on to the Imaging Dementia-Evidence for Amyloid Scanning study, including 249 patients from 2018 to 2019, and MissionAD, a dataset of 437 biobanked patient samples obtained at screenings during 2016 to 2019.

The PrecivityAD™ test: Accurate and reliable LC-MS/MS assays for quantifying plasma amyloid beta 40 and 42 and apolipoprotein E proteotype for the assessment of brain amyloidosis.

Background: There is an unmet need for an accessible, less invasive, cost-effective method to facilitate clinical trial enrollment and aid in clinical Alzheimer's disease (AD) diagnosis. APOE genotype affects the clearance and deposition of amyloid-beta (Aβ) with APOE4 carriers having increased risk while APOE2 alleles appear to be protective. Lower plasma Aβ42/40 correlates with brain amyloidosis.

A blood-based diagnostic test incorporating plasma Aβ42/40 ratio, ApoE proteotype, and age accurately identifies brain amyloid status: findings from a multi cohort validity analysis.

Background: The development of blood-based biomarker tests that are accurate and robust for Alzheimer's disease (AD) pathology have the potential to aid clinical diagnosis and facilitate enrollment in AD drug trials. We developed a high-resolution mass spectrometry (MS)-based test that quantifies plasma Aβ42 and Aβ40 concentrations and identifies the ApoE proteotype. We evaluated robustness, clinical performance, and commercial viability of this MS biomarker assay for distinguishing brain amyloid status.

Ga-metalloprobes: monitoring the impact of geometrical isomers on accumulation profiles in rat cardiomyoblasts and human breast carcinoma cells.

Geometrically similar monocationic gallium(iii) complexes and their radiolabeled SPECT counterparts were obtained from Schiff base precursor ligands using ligand exchange reactions to evaluate the impact of and -isomers on their cellular accumulation profiles in rat cardiomyoblasts (H9c2(2-1)) and human breast carcinoma (MCF-7neo) cells. Ga-metalloprobes comprising -phenolates showing an overall octahedral geometry and exhibiting uniform spatial distribution of positive charges on their molecular surface show steady-state accumulation in H9c2(2-1) and MCF-7neo cells, and localize in the mitochondria of the cells. Importantly, the surrogate geometrically similar and monocationic metalloprobe counterparts possessing the arrangement of phenolates do not show cellular uptake in H9c2(2-1) and MCF-7neo cells.

Metalloprobes: Fluorescence imaging of multidrug resistance (MDR1) P-Glycoprotein (Pgp)-mediated functional transport activity in cellulo.

Radiolabeled metalloprobes offer sensitive tools for evaluating quantitative accumulation of chemical entities within pooled cell populations. Although beneficial in translational nuclear imaging, this method precludes interrogation of effects resulting from variations at a single cell level, within the same segment of cell population. Compared with radiotracer bioassays, fluorescence imaging offers a cost-efficient technique to assess accumulation of metalloprobes at a single cell level, and determine their intracellular localization under live cell conditions.

(67/68)Galmydar: A metalloprobe for monitoring breast cancer resistance protein (BCRP)-mediated functional transport activity.

Introduction: For stratification of chemotherapeutic choices, radiopharmaceuticals capable of imaging breast cancer resistance protein (BCRP/ABCG2)-mediated functional transport are desired. To accomplish this objective, Galmydar, a fluorescent and moderately hydrophobic Ga(III) cationic complex and its (67/68)Ga-radiolabeled counterparts were interrogated in HEK293 cells stably transfected with BCRP and their WT counterparts transfected with empty vector. Additionally, the sensitivity and specificity of (68)Ga-Galmydar to evaluate functional expression of BCRP at the blood-brain barrier (BBB) was investigated in gene-knockout mdr1a/1b(-/-) (double knockout, dKO) and mdr1a/1b(-/-)ABCG2(-/-) (triple knockout, tKO) mouse models.

Gold Nanoparticles Doped with (199) Au Atoms and Their Use for Targeted Cancer Imaging by SPECT.

Gold nanoparticles have been labeled with various radionuclides and extensively explored for single photon emission computed tomography (SPECT) in the context of cancer diagnosis. The stability of most radiolabels, however, still needs to be improved for accurate detection of cancer biomarkers and thereby monitoring of tumor progression and metastasis. Here, the first synthesis of Au nanoparticles doped with (199)Au atoms for targeted SPECT tumor imaging in a mouse triple negative breast cancer (TNBC) model is reported.

Utilizing the Multiradionuclide Resolving Power of SPECT and Dual Radiolabeled Single Molecules to Assess Treatment Response of Tumors.

Purpose: Single photon emission computed tomography (SPECT) radionuclide pairs having distinct decay rates and different energy maxima enable simultaneous detection of dual gamma signals and real-time assessment of dynamic functional and molecular processes in vivo. Here, we report image acquisition and quantification protocols for a single molecule labeled with two different radionuclides for functional SPECT imaging.

Procedures: LS370 and LS734 were prepared using modular solid phase peptide synthesis.

A generator-produced gallium-68 radiopharmaceutical for PET imaging of myocardial perfusion.

Lipophilic cationic technetium-99m-complexes are widely used for myocardial perfusion imaging (MPI). However, inherent uncertainties in the supply chain of molybdenum-99, the parent isotope required for manufacturing 99Mo/99mTc generators, intensifies the need for discovery of novel MPI agents incorporating alternative radionuclides. Recently, germanium/gallium (Ge/Ga) generators capable of producing high quality 68Ga, an isotope with excellent emission characteristics for clinical PET imaging, have emerged.

Interrogation of multidrug resistance (MDR1) P-glycoprotein (ABCB1) expression in human pancreatic carcinoma cells: correlation of 99mTc-Sestamibi uptake with western blot analysis.

Histopathological studies indicate that ∼63% of pancreatic tumors express multidrug resistance (MDR1) P-glycoprotein (Pgp) and its polymorphic variants. However, Pgp expression detected at the mRNA or protein level does not always correlate with functional transport activity. Because Pgp transport activity is affected by specific mutations and the phosphorylation state of the protein, altered or less active forms of Pgp may also be detected by PCR or immunohistochemistry, which do not accurately reflect the status of tumor cell resistance.

A new nucleoside analogue with potent activity against mutant sr39 herpes simplex virus-1 (HSV-1) thymidine kinase (TK).

Nucleoside analogues, such as penciclovir, ganciclovir, acyclovir, and their fluoro-substituted derivatives, have wide utility as antivirals. Among these analogues, FHBG ((18)F-Fluorohydroxybutylguanine) is a well-validated PET (positron emission tomography) probe for monitoring reporter gene expression. To evaluate whether or not imposing rigidity into the flexible side chain of FHBG 4 could also impact its interaction, with amino acid residues within the binding site of HSV1-TK (Herpes Simplex Virus-1 Thymidine Kinase), thus influencing its cytotoxic activity.

Cerenkov radiation energy transfer (CRET) imaging: a novel method for optical imaging of PET isotopes in biological systems.

Background: Positron emission tomography (PET) allows sensitive, non-invasive analysis of the distribution of radiopharmaceutical tracers labeled with positron (β(+))-emitting radionuclides in small animals and humans. Upon β(+) decay, the initial velocity of high-energy β(+) particles can momentarily exceed the speed of light in tissue, producing Cerenkov radiation that is detectable by optical imaging, but is highly absorbed in living organisms.

Principal Findings: To improve optical imaging of Cerenkov radiation in biological systems, we demonstrate that Cerenkov radiation from decay of the PET isotopes (64)Cu and (18)F can be spectrally coupled by energy transfer to high Stokes-shift quantum nanoparticles (Qtracker705) to produce highly red-shifted photonic emissions.

Synthesis, characterization, and molecular structure of a novel zinc (II) complex: assessment of impact of MDR1Pgp expression on its cytotoxic activity.

Zinc(II)complex (3) {bis(3-ethoxy-2-hydroxy-benzylidene)-N,N'-bis(2,2-dimethyl-3-aminopropyl)ethylenediamine}-zinc(II); [(3-OEt-ENBDMPI)Zn(II)] was obtained in situ by a ligand exchange reaction involving zinc(II) acetylacetonate and the Schiff-base ligand obtained in situ. For assessing ability of 3 to act as a transport substrate of multidrug resistance (MDR1) P-glycoprotein (Pgp), its cytotoxic activity was evaluated in human epidermal carcinoma drug-sensitive KB 3-1 (Pgp-) and drug resistant KB 8-5 (Pgp+) cells. Compared with its cationic gallium(III) counterpart 4 showing cytotoxicity profiles consistent with its recognition as a Pgp substrate, the neutral zinc(II) complex 3 did not display cytotoxicity profiles (at pharmacologically relevant concentrations <10 µM) modified by expression of Pgp.

Synthesis, molecular structure, and validation of metalloprobes for assessment of MDR1 P-glycoprotein-mediated functional transport.

Unlabelled: The human genome is known to consist of 49 ATP-binding cassette (ABC) transporter genes. Among these ABC proteins, overexpression of multidrug resistance (MDR1) P-glycoprotein (Pgp/ABCB1) is the best characterized barrier to successful chemotherapeutic treatments, impacts pharmacokinetics of numerous recognized drugs, and is also quickly emerging as an important target in the development of neurodegenerative diseases. Therefore, there exists an urgent need to seek radiopharmaceuticals, incorporated with generator-produced radionuclides to assist their widespread deployment, for noninvasive assessment of Pgp-mediated functional transport activity in vivo.

The neurofibromatosis type 1 tumor suppressor controls cell growth by regulating signal transducer and activator of transcription-3 activity in vitro and in vivo.

Neurofibromatosis type 1 (NF1) is a common cancer predisposition syndrome in which affected individuals develop benign and malignant nerve tumors. The NF1 gene product neurofibromin negatively regulates Ras and mammalian target of rapamycin (mTOR) signaling, prompting clinical trials to evaluate the ability of Ras and mTOR pathway inhibitors to arrest NF1-associated tumor growth. To discover other downstream targets of neurofibromin, we performed an unbiased cell-based high-throughput chemical library screen using NF1-deficient malignant peripheral nerve sheath tumor (MPNST) cells.

Targeted chemotherapy in drug-resistant tumors, noninvasive imaging of P-glycoprotein-mediated functional transport in cancer, and emerging role of Pgp in neurodegenerative diseases.

Multidrug resistance (MDR) mediated by overexpression of P-glycoprotein (Pgp) is one of the best characterized transporter-mediated barriers to successful chemotherapy in cancer patients and is also a rapidly emerging target in the progression of neurodegenerative disorders such as Alzheimer's and Parkinson's diseases. Therefore, strategies capable of delivering chemotherapeutic agents into drug-resistant tumors and targeted radiopharmaceuticals acting as ultrasensitive molecular imaging probes for detecting functional Pgp expression in vivo could be expected to play a vital role in systemic biology as personalized medicine gains momentum in the twenty-first century. While targeted therapy could be expected to deliver optimal doses of chemotherapeutic drugs into the desired targets, the interrogation of Pgp-mediated transport activity in vivo via noninvasive imaging techniques (SPECT and PET) would be beneficial in stratification of patient populations likely to benefit from a given therapeutic treatment, thereby assisting management of drug resistance in cancer and treatment of neurodegenerative diseases.

Synthesis, characterization, and antimalarial activity of novel schiff-base-phenol and naphthalene-amine ligands.

Emergence of chloroquine (CQ) resistant Plasmodium falciparum strains necessitates discovery of inexpensive antimalarial drugs capable of targeting CQ-resistant strains. Towards this objective, herein we have synthesized and characterized naphthalene-Schiff bases or naphthalene-amine phenols. Among these compounds, 7 demonstrated a significant bioactivity with a half-maximal inhibitory concentration (IC(50)) of 1.

Metalloprobes: synthesis, characterization, and potency of a novel gallium(III) complex in human epidermal carcinoma cells.

Multidrug resistance (MDR) mediated by overexpression of the MDR1 gene product, P-glycoprotein (Pgp), represents one of the best characterized barriers to chemotherapeutic treatment in cancer and may be a pivotal factor in progression of Alzheimer's disease (AD). Thus, agents capable of probing Pgp-mediated transport could be beneficial in biomedical imaging. Herein, we synthesized and structurally characterized a gallium(III) complex (5) of the naphthol-Schiff base ligand.

Second-generation triple reporter for bioluminescence, micro-positron emission tomography, and fluorescence imaging.

Bioluminescence, positron emission tomography (PET), and fluorescence modalities are currently available for noninvasive imaging in vivo, each with its own merits. To exploit the combined strengths of each and facilitate multimodality imaging, we engineered a dual-reporter construct in which firefly luciferase (FLuc) and a 12-amino acid nonstructural linker were fused in frame to the N-terminus of a mutant herpes simplex virus thymidine kinase (mNLS-SR39TK) kinetically enhanced for positron emission tomography (PET). Furthermore, a triple-reporter construct was developed in which monster green fluorescent protein (MGFP), a recently available enhanced fluorescent protein, was introduced into the fusion vector downstream of an internal ribosome entry site (IRES) to allow analysis by fluorescence microscopy or flow cytometry without compromising the specific activities of the upstream fusion components.

Metalloantimalarials: synthesis and characterization of a novel agent possessing activity against Plasmodium falciparum.

The synthesis, characterization, and antimalarial potency of an amine-phenol complex of gallium(III), [{1,12-bis(2-hydroxy-3-methoxy-5-(quinolin-3-yl)-benzyl)-1,5,8,12-tetraazadodecane}-gallium(III)]+, [Ga-3-M-5-Quadd]+ (7) is described; a novel agent that targets Plasmodium falciparum strains.

Metalloantimalarials: targeting of P. falciparum strains with novel iron(III) and gallium(III) complexes of an amine phenol ligand.

Emergence of chloroquine (CQ)-resistant Plasmodium falciparum strains necessitates discovery of potent and inexpensive antimalarial drugs. The high cost of new drugs negatively impacts their access and distribution in the regions of the world with scarce economic resources. While exploring structure-activity relationships, using gallium(III) as a surrogate marker for iron(III), we found cationic, and moderately hydrophobic, compounds, [[1,12-bis(2-hydroxy-3-ethyl-benzyl)-1,5,8,12-tetraazadodecane]metal(III)](+) (metal = Fe(III) and Ga(III); [Fe-3-Eadd](+), 3; [Ga-3-Eadd](+), 4), that possessed antimalarial activity.

Synthesis, characterization, and molecular structure of a gallium(III) complex of an amine-phenol ligand with activity against chloroquine-sensitive Plasmodium falciparum strains.

Emergence of chloroquine-resistant Plasmodium falciparum strains necessitates discovery of novel antimalarial drugs, especially if the agents can be synthesized from commercially available, inexpensive precursors via short synthetic routes. While exploring structure-activity relationships, we found a gallium(III) complex, [(1,12-bis(2-hydroxy-5-methoxybenzyl)-1,5,8,12-tetraazadodecane)-gallium(III)](+) [Ga-5-Madd](+), 1, that possessed antimalarial efficacy. Like previously reported complexes, the crystal structure of 1 revealed gallium(III) in a symmetrical octahedral environment surrounded by four secondary amine nitrogen atoms in equatorial plane and two axial oxygen atoms.