Linking isotope analysis and paleopathology: An andean perspective.

This paper reviews the significant advances in isotopic investigations in Andean South America and directs scholars to explore new theoretical and analytical directions, specifically the applicability of isotope data to paleopathology. Excellent preservation and large skeletal collections of human remains make the Central Andes ideal for biogeochemical reconstructions and advancements in isotopic methods. Our aims are twofold: first, we present a meta-analysis of stable and radiogenic isotope research in the Central Andes since 1985, and highlight those that combine analyses of isotope ratios and pathological conditions. Second, we discuss useful directions for incorporating stable isotope analysis more explicitly in studies of paleopathology in the Andes more in the future. Principle research foci have described dietary variation and regional population mobility since the 1980s, where early methodological explorations identified significant trends in isotopic variation. For the years 1980-2017, we identified 96 scholarly publications through a meta-data analysis of major peer-reviewed journals, book chapters, and conference proceedings. These demonstrate specific trends in topical and methodological preferences across the Andean region and a shift from 10 publications pre-1997 to 67 in the last 10 years. However, combined isotope and paleopathology studies in this region remain sparse; given the ecological, geological, and cultural complexity of the Central Andes, analyses of pathological conditions in different regions would significantly benefit from the information on diet, mobility, and local ecology that isotope ratios provide. Isotope analysis requires destruction of archaeological tissues, and interpreting isotope data can be complex, but it can also provide unique insights into the pathogenesis of multifactorial conditions and assist differential diagnosis. Therefore, we also discuss research designs for pairing isotopic and paleopathological variables that will allow researchers to better capture disease ecologies in archaeological samples and their variation across different regions, within related sites, and within individual lifespans.

Current trends in isotope-coded derivatization liquid chromatographic-mass spectrometric analyses with special emphasis on their biomedical application.

Currently, LC-MS has various applications in different areas such as metabolomics, pharmacokinetics, and pathological studies. Yet, matrix effects resulting from co-existing constituents remain a major problem for LC-MS [or LC-tandem mass spectrometry (LC-MS/MS)]. Moreover, technical problems and instrumental drifts may lead to ion abundance variance. Thus, an internal standard (IS) is required to guarantee the accuracy and precision of the method. Because of their limited number, isotope-coded derivatization (ICD) has been recently introduced to overcome this problem. For ICD, a stable heavy isotope-coded moiety is used for labeling the standard or the control sample and the formed products can act as ISs. A light form of the reagent is used for labeling the sample. Then, both are mixed and analyzed by LC-MS(/MS). This strategy permits the identification of different unknown analytes including potential metabolites and disease biomarkers. All these attributes lead to persistent growth in the applications of ICD LC-MS(/MS) in various biomedical branches. In this article we review the ICD methods published in the last eight years for biomedical applications as well as briefly summarize other applications for environmental and food analyses as some of their used ICD reagents were further applied for analyzing biological specimens or have the potential for that.

Production of isotope-labeled proteins in insect cells for NMR.

Baculovirus-infected insect cells have become a powerful tool to express recombinant proteins for structural and functional studies by NMR spectroscopy. This article provides an introduction into the insect cell/baculovirus expression system and its use for the production of recombinant isotope-labeled proteins. We discuss recent advances in inexpensive isotope-labeling methods using labeled algal or yeast extracts as the amino acid source and give examples of advanced NMR applications for proteins, which have become accessible by this eukaryotic expression host.

Improving Marine Ecosystem Models with Biochemical Tracers.

Empirical data on food web dynamics and predator-prey interactions underpin ecosystem models, which are increasingly used to support strategic management of marine resources. These data have traditionally derived from stomach content analysis, but new and complementary forms of ecological data are increasingly available from biochemical tracer techniques. Extensive opportunities exist to improve the empirical robustness of ecosystem models through the incorporation of biochemical tracer data and derived indices, an area that is rapidly expanding because of advances in analytical developments and sophisticated statistical techniques. Here, we explore the trophic information required by ecosystem model frameworks (species, individual, and size based) and match them to the most commonly used biochemical tracers (bulk tissue and compound-specific stable isotopes, fatty acids, and trace elements). Key quantitative parameters derived from biochemical tracers include estimates of diet composition, niche width, and trophic position. Biochemical tracers also provide powerful insight into the spatial and temporal variability of food web structure and the characterization of dominant basal and microbial food web groups. A major challenge in incorporating biochemical tracer data into ecosystem models is scale and data type mismatches, which can be overcome with greater knowledge exchange and numerical approaches that transform, integrate, and visualize data.

The Past, Current Studies and Future of Organometallic 99mTc(CO)3 Labeled Peptides and Proteins.

The labeling of biomolecule using 99mTc-tricarbonyl is an interesting tool for the diagnosis of diseases. This labeling startegy has several advantages as compared to other common radiolabeling techniques. This review is a complete overview of synthesis and chemistry of 99mTc-tricarbonyl molecule for labeling peptides and proteins. Also, the effect of ligand type on the stability and in vivo biodistribution of ;99m;Tc-tricarbonyl labeled biomolecules are discussed. Chemistries of cyclopentadienyl and hexa histidine tag as two important bifunctional chelating agents (BFCA) are presented. The in vitro and in vivo behaviors of some 99mTc-tricarbonyl labeled peptides and proteins are explained. Preclinical outcomes revealed that these labeled compounds are biologically, kinetically and thermodynamically stable. Findings showed that 99mTc-tricarbonyl labeled biomolecules are promising tools for future clinical applications in image diagnosis.

Super-SILAC: current trends and future perspectives.

Stable isotope labeling with amino acids in cell culture (SILAC) has risen as a powerful quantification technique in mass spectrometry (MS)-based proteomics in classical and modified forms. Previously, SILAC was limited to cultured cells because of the requirement of active protein synthesis; however, in recent years, it was expanded to model organisms and tissue samples. Specifically, the super-SILAC technique uses a mixture of SILAC-labeled cells as a spike-in standard for accurate quantification of unlabeled samples, thereby enabling quantification of human tissue samples. Here, we highlight the recent developments in super-SILAC and its application to the study of clinical samples, secretomes, post-translational modifications and organelle proteomes. Finally, we propose super-SILAC as a robust and accurate method that can be commercialized and applied to basic and clinical research.

Therapeutic radionuclides in nuclear medicine: current and future prospects.

The potential use of radionuclides in therapy has been recognized for many decades. A number of radionuclides, such as iodine-131 ((131)I), phosphorous-32 ((32)P), strontium-90 ((90)Sr), and yttrium-90 ((90)Y), have been used successfully for the treatment of many benign and malignant disorders. Recently, the rapid growth of this branch of nuclear medicine has been stimulated by the introduction of a number of new radionuclides and radiopharmaceuticals for the treatment of metastatic bone pain and neuroendocrine and other malignant or non-malignant tumours. Today, the field of radionuclide therapy is enjoying an exciting phase and is poised for greater growth and development in the coming years. For example, in Asia, the high prevalence of thyroid and liver diseases has prompted many novel developments and clinical trials using targeted radionuclide therapy. This paper reviews the characteristics and clinical applications of the commonly available therapeutic radionuclides, as well as the problems and issues involved in translating novel radionuclides into clinical therapies.

Recent advances in mapping environmental microbial metabolisms through 13C isotopic fingerprints.

After feeding microbes with a defined (13)C substrate, unique isotopic patterns (isotopic fingerprints) can be formed in their metabolic products. Such labelling information not only can provide novel insights into functional pathways but also can determine absolute carbon fluxes through the metabolic network via metabolic modelling approaches. This technique has been used for finding pathways that may have been mis-annotated in the past, elucidating new enzyme functions, and investigating cell metabolisms in microbial communities. In this review paper, we summarize the applications of (13)C approaches to analyse novel cell metabolisms for the past 3 years. The isotopic fingerprints (defined as unique isotopomers useful for pathway identifications) have revealed the operations of the Entner-Doudoroff pathway, the reverse tricarboxylic acid cycle, new enzymes for biosynthesis of central metabolites, diverse respiration routes in phototrophic metabolism, co-metabolism of carbon nutrients and novel CO(2) fixation pathways. This review also discusses new isotopic methods to map carbon fluxes in global metabolisms, as well as potential factors influencing the metabolic flux quantification (e.g. metabolite channelling, the isotopic purity of (13)C substrates and the isotopic effect). Although (13)C labelling is not applicable to all biological systems (e.g. microbial communities), recent studies have shown that this method has a significant value in functional characterization of poorly understood micro-organisms, including species relevant for biotechnology and human health.

Applications of stable isotopes in clinical pharmacology.

This review aims to present an overview of the application of stable isotope technology in clinical pharmacology. Three main categories of stable isotope technology can be distinguished in clinical pharmacology. Firstly, it is applied in the assessment of drug pharmacology to determine the pharmacokinetic profile or mode of action of a drug substance. Secondly, stable isotopes may be used for the assessment of drug products or drug delivery systems by determination of parameters such as the bioavailability or the release profile. Thirdly, patients may be assessed in relation to patient-specific drug treatment; this concept is often called personalized medicine. In this article, the application of stable isotope technology in the aforementioned three areas is reviewed, with emphasis on developments over the past 25 years. The applications are illustrated with examples from clinical studies in humans.

When peptides fly: advances in Drosophila proteomics.

In the past decade, improvements in genome annotation, protein fractionation methods and mass spectrometry instrumentation resulted in rapid growth of Drosophila proteomics. This review presents the current status of proteomics research in the fly. Areas that have seen major advances in recent years include efforts to map and catalog the Drosophila proteome and high-throughput as well as targeted studies to analyze protein-protein interactions and post-translational modifications. Stable isotope labeling of flies and other applications of quantitative proteomics have opened up new possibilities for functional analyses. It is clear that proteomics is becoming an indispensable tool in Drosophila systems biology research that adds a unique dimension to studying gene function.

Antibody vectors for imaging.

Noninvasive molecular imaging approaches include nuclear, optical, magnetic resonance imaging, computed tomography, ultrasound, and photoacoustic imaging, which require accumulation of a signal delivered by a probe at the target site. Monoclonal antibodies are high affinity molecules that can be used for specific, high signal delivery to cell surface molecules. However, their long circulation time in blood makes them unsuitable as imaging probes. Efforts to improve antibodies pharmacokinetics without compromising affinity and specificity have been made through protein engineering. Antibody variants that differ in antigen binding sites and size have been generated and evaluated as imaging probes to target tissues of interest. Fast clearing fragments, such as single-chain variable fragment (scFv; 25 kDa), with 1 antigen-binding site (monovalent) demonstrated low accumulation in tumors because of the low exposure time to the target. Using scFv as building block to produce larger, bivalent fragments, such as scFv dimers (diabodies, 50 kDa) and scFv-fusion proteins (80 kDa minibodies and 105 kDa scFv-Fc), resulted in higher tumor accumulation because of their longer residence time in blood. Imaging studies with these fragments after radiolabeling have demonstrated excellent, high-contrast images in gamma cameras and positron emission tomography scanners. Several studies have also investigated antibody fragments conjugated to fluorescence (near infrared dyes), bioluminescence (luciferases), and quantum dots for optical imaging and iron oxides nanoparticles for magnetic resonance imaging. However, these studies indicate that there are several factors that influence successful targeting and imaging. These include stability of the antibody fragment, the labeling chemistry (direct or indirect), whether critical residues are modified, the number of antigen expressed on the cell, and whether the target has a rapid recycling rate or internalizes upon binding. The preclinical data presented are compelling, and it is evident that antibody-based molecular imaging tracers will play an important future role in the diagnosis and management of cancer and other diseases.

When metagenomics meets stable-isotope probing: progress and perspectives.

The application of metagenomics, the culture-independent capture and subsequent analysis of genomic DNA from the environment, has greatly expanded our knowledge of the diversity of microbes and microbial protein families; however, the metabolic functions of many microorganisms remain largely unknown. DNA stable-isotope probing (DNA-SIP) is a recently developed method in which the incorporation of stable isotope from a labelled substrate is used to identify the function of microorganisms in the environment. The technique has now been used in conjunction with metagenomics to establish links between microbial identity and particular metabolic functions. The combination of DNA-SIP and metagenomics not only permits the detection of rare low-abundance species from metagenomic libraries but also facilitates the detection of novel enzymes and bioactive compounds.

An overview of the diagnostic and therapeutic use of monoclonal antibodies in medicine.

Monoclonal antibodies, which include murine, chimeric, humanized and fully human antibodies, bind to their target receptors with high affinity and specificity. In the last two decades several different monoclonal antibodies have been approved by the Food and Drug Administration for therapeutic purposes, and some of these and others have also been radiolabelled for diagnostic and therapeutic purposes. This field is in continuous evolution and this overview highlights the role of radiolabelled antibodies in research and clinical setting.

Clinical role of anti-granulocyte MoAb versus radiolabeled white blood cells.

Scintigraphy with white blood cells (WBC), labeled with ¹¹¹In-oxine or (99m)Tc-hexamethylpropyleneamine oxime (HMPAO), and anti-granulocyte scintigraphy using (99m)Tc-labeled monoclonal antibodies (MoAb), or fragments thereof, are established procedures for the diagnostic workup of infectious or inflammatory disease processes. Clinically severe afflictions such as fever of unknown origin (FUO), infectious joint replacements, osteomyelitis, vascular graft infections or cardiovascular infections often present where noninvasive proof of granulocytic inflammatory activity is more useful than mere morphology-based radiological diagnostic approaches. The labeling differences between WBC and antigranulocyte antibodies produce different pharmacokinetics and patterns of tracer accumulation and distribution. Together with the physical imaging properties of the respective isotope used for imaging, the diagnostic value of a tracer depends on the clinical setting. Thus, despite the easier and safer handling of antibody-based in-vivo labeling, indications for in-vivo labeled WBC remain. As a consequence there is as yet no ideal inflammation tracer, also bearing in mind that neither WBCs nor antibody-diagnostics can reliably differentiate sterile inflammation from infection. Although positron emission tomography (PET) using e.g. FDG-PET is replacing conventional scintigraphies in some indications, both in vivo and in vitro labelled leukocytes will remain an important clinical pillar in the diagnosis of infection and inflammation.

Nonspecific human immunoglobulin G for imaging infection and inflammation: what did we learn?

Radiolabeled human non specific immunoglobulin G (IgG or HIG) was proposed in the early nineties as a potential tracer for imaging infection and sterile inflammation. Formulations with ¹¹¹In and (99m)Tc as the label were developed and extensive preclinical work was undertaken to assess its potential as a diagnostic agent. ¹¹¹In-HIG was used in a number of clinical studies and proved efficient in detecting orthopedic infections, especially in patients with prostheses, fever of unknown origin, opportunistic infections in immunocompromised patients, including patients infected with the human immunodeficiency virus and neutropenic patients. In the latter patients, there was no need for blood manipulation to harvest white cells for leukocyte labeling which was a considerable advantage. (99m)Tc-HIG was also successfully used for imaging sterile arthritis, especially rheumatoid arthritis. Two decades later, radiolabeled HIG is almost completely abandoned as a general purpose tracer for imaging infection and inflammation and this article aims to find out why this has happened.

Clinical impact of radiolabeled anti-CD4 antibodies in the diagnosis of rheumatoid arthritis.

Human rheumatoid arthritis (RA) is characterized by severe chronic synovitis with abundance of CD4-positive T-cells and macrophages in the inflamed synovial tissue. These cells likely play a central pathogenetic role in RA and experimental models of arthritis. CD4 is a surface molecule present on the helper/inducer subset of T lymphocytes and macrophages, although with a lower density on the latter. CD4+ T-cells/macrophages and their cytokine products, therefore, represent potential therapeutic and diagnostic targets in RA. CD4, a 55 kDa monomeric glycoprotein, binds as a T-cell coreceptor to conserved areas of the major histocompatibility complex II on antigen-presenting cells, and thereby participates in the formation of the immunological synapse and the provision of the so-called "second signal" required for full activation of T-helper cells. A specific diagnostic or therapeutic approach is the direct targeting of CD4+ T-cells by anti-CD4 monoclonal antibodies (mAbs). In addition to therapeutic clinical trials with anti-CD4 mAbs in RA, which have yielded only ambiguous results, anti-CD4 mAbs have also been developed and applied for diagnostic purposes. The studies thus far conducted in RA have focused on the following aspects: 1) comparison of anti-CD4 mAb imaging to the established early methylene diphosphonate (MDP) scan; 2) biodistribution/ pharmacokinetics studies; and 3) specificity of joint imaging with anti-CD4 mAbs in comparison to control immunoglobulins with irrelevant specificity. The available results in RA and arthritis models show that 99mTc-anti-CD4 mAbs are well-suited to actively image diseased joints, and clearly allow more specific imaging than 99mTc-MDP or control immunoglobulins. Because effective treatment is known to reduce the density of CD4+ cells in the inflamed synovial membrane, diagnostic methods targeted to CD4 warrant further attention, also for early diagnosis of clinically silent joints, precise description of the cellular infiltrates, and monitoring of anti-rheumatic therapy.

The role of radiolabelled anti-TNFa monoclonal antibodies for diagnostic purposes and therapy evaluation.

Radiolabelled cytokines and monoclonal antibodies are an emerging class of radiopharmaceuticals for imaging inflammation. These radiopharmaceuticals bind to their targets with high affinity and specificity and therefore have excellent diagnostic potential for imaging of patients with chronic inflammatory diseases. One of the key cytokines involved in the process of inflammation is tumor necrosis factor alpha (TNFα). With the introduction of anti-TNFα monoclonal antibodies over the past decade, treatment of inflammatory diseases has evolved, which allowed remarkable advances in controlling signs and symptoms of inflammation and in slowing destruction. However, drugs may lose efficacy over time in patients or induce adverse events. Using immediately the right medication tailored to the patient's molecular status avoids unnecessary costs and side effects. Significant differences in mechanisms of action and in therapy outcome, depending on the disease to be treated, exist among the different TNFα antagonists. Labelling these agents may help to find out if TNFα is present in the inflammatory process and will therefore help in therapy prediction and stratification in the individual patient. This review describes the role of cytokines and in particular of TNFα in the process of inflammation as well as the influence of TNFα in some well-known and common inflammatory diseases, such as rheumatoid arthritis, ankylosing spondylitis, inflammatory bowel diseases, psoriasis and sarcoidosis. The main focus of this article is to review the role of molecular imaging with radiolabelled anti-TNFα monoclonal antibodies for diagnostic purposes, and in therapy precision, decision-making and evaluation.