Single cell analysis of cancer cells using an improved RT-MLPA method has potential for cancer diagnosis and monitoring

Development of certain benzylidene coumarin derivatives as anti-prostate cancer agents targeting EGFR and PI3Kβ kinases

Novel coumarin derivatives were synthesised and tested for their cytotoxicity against human cancer cells (PC-3 and MDA-MB-231). Compounds 5, 4b, and 4a possessed potent cytotoxic activity against PC-3 cells with IC50 3.56, 8.99, and 10.22 µM, respectively. Compound 4c displayed cytotoxicity more than erlotinib in the MDA-MB-231 cells with IC50 8.5 µM. Moreover, compound 5 exhibited potent inhibitory activity on EFGR with IC50 0.1812 µM, as well as PI3Kβ inhibitory activity that was twofold higher than LY294002, suggesting that this compound has a dual EGFR and PI3Kβ inhibiting activity. Docking aligns with the in vitro results and sheds light on the molecular mechanisms underlying dual targeting. Furthermore, compound 5 decreased AKT and m-TOR expression in PC-3 cells, showing that it specifically targets these cells via the EGFR/PI3K/Akt/m-TOR signalling pathway. Simultaneously, compound 5 caused cell cycle arrest at S phase and induced activation of both intrinsic and extrinsic apoptotic pathways.

Detection and differentiation of seven porcine respiratory pathogens using a multiplex ligation-dependent probe amplification assay

Respiratory diseases due to viral or bacterial agents, either alone or in combination, cause substantial economic burdens to the swine industry worldwide. Rapid and reliable detection of causal pathogens is crucial for effective epidemiological surveillance and disease management. This research aimed to employ the multiplex ligation-dependent probe amplification (MLPA) assay for simultaneous detection of seven distinct pathogens causing respiratory problems in swine, porcine reproductive and respiratory syndrome virus (PRRSV), swine influenza virus (SIV), porcine respiratory coronavirus (PRCV), porcine circovirus type 2 (PCV2), Pasteurella multocida, Actinobacillus pleuropneumoniae, and Glässerella parasuis. The results indicated no probe cross-reactivity among the seven target agents with other swine pathogens. The detection limits ranged from 5 to 34 copies per assay for the target organisms. The MLPA assay was evaluated with 88 samples and compared to real-time or multiplex PCR for the target pathogens. The MLPA assay demonstrated high relative test sensitivities (100 %) and reasonable to good relative specificities at 62.5 %, 95.1 %, 86.8 %, and 97.6 % for PRRSV, P. multocida, G. parasuis, and PCV2, respectively, relative to comparator PCR assays. In 71 samples where MLPA and comparator PCR assays matched exactly, infections were detected in 64 samples (90.1 %), with PRRSV being the most commonly found virus and 50.7 % of the samples showing co-infection with two to five of the pathogens. This approach serves as a valuable tool for conducting differential diagnoses and epidemiological investigations of pathogen prevalence within swine populations.

Impact of anthracycline-based chemotherapy on RB1 gene methylation in peripheral blood leukocytes and biomarkers of oxidative stress and inflammation in sarcoma patients

PURPOSE

We investigated the impact of anthracycline-based chemotherapy on methylation status of RB1 gene in peripheral blood leukocytes together with parameters of oxidative stress and inflammation in sarcoma patients.

PATIENTS/METHODS

Blood samples were collected from 51 consecutive newly diagnosed sarcoma patients admitted to University Hospital Center Zagreb (Zagreb, Croatia) for first-line chemotherapy before the first cycle and post-chemotherapy. Methylation and copy number variation (CNV) of leukocyte RB1 gene were assessed using MS-MLPA probes. In addition, in blood samples, parameters of oxidative stress (ROS, MDA, SOD, and GSH) and inflammation (CRP, WBC, and NBC) were followed.

RESULTS

In pre-chemotherapy samples, no CNVs and aberrant methylation of CpG106 promoter region of RB1 gene were detected; however, one patient had hypermethylation (by approximately 10%) of imprinted locus CpG85 in intron 2 of RB1 gene. In addition, a very good correlation of the tumor burden and CRP and tumor burden and GSH was found. The anthracycline-based chemotherapy reverts methylation of RB1 gene-imprinted locus CpG85 to normal level. Moreover, inflammation and oxidative stress parameters such as CRP, WBC, ROS, and MDA were significantly decreased in post-chemotherapy samples.

CONCLUSION

This single-centered study on a cohort of consecutive sarcoma patients indicates that sarcoma patients can have aberrant germline DNA methylation and confirms the relationship of tumor burden with inflammation and oxidative stress. The applied chemotherapy protocols reverted RB1 gene methylation to normal level and decreased the level of inflammation and oxidative damage, thus indicating chemotherapy benefit to the patient's health status.

Kiwifruit (Actinidia deliciosa) aqueous extract improves hyperglycemia, testicular inflammation, apoptosis, and tissue structure induced by Streptozotocin via oxidative stress inhibition

Diabetes mellitus (DM) is a well-known hyperglycemic metabolic condition identified by oxidative stress and biological function disruption. Kiwifruit is a valuable source of polyphenols and vitamin C with great antioxidant, nutritional, and health-promoting effects. Therefore, this study was initiated to explore the antioxidant and anti-hyperglycemic effects of kiwifruit aqueous extract (KFE) against oxidative injury and testis dysfunction in rats with diabetes. Twenty-four male Wistar Albino rats (160-170 g) were divided into four groups: Group 1 served as the control, Group 2 supplemented orally with kiwifruit extract (KFE; 1 g/kg/day) for one month, Group 3 was treated with a single streptozotocin dose (STZ; 50 mg/kg ip), and Group 4 where the diabetic rats were administered with KFE, respectively. According to the results, the GC-MS analysis of KFE revealed several main components with strong antioxidant properties. In diabetic rats, lipid peroxidation and hyperglycemia were accompanied by perturbations in hormone levels and sperm characteristics. Antioxidant enzymes, glutathione content, aminotransferase, phosphatase activities, and protein content were decreased. Furthermore, histology, immunohistochemical PCNA expression, and histochemical analysis of collagen, DNA, RNA, and total protein. were altered in rat testis sections, supporting the changes in biochemistry. Furthermore, diabetic rats supplemented with KFE manifested considerable amendment in all the tested parameters besides improved tissue structure and gene expressions (NF-kB, p53, IL-1β, Bax, IL-10, and Bcl2) relative to the diabetic group. In conclusion, KFE has beneficial effects as it can improve glucose levels and testis function, so it might be used as a complementary therapy in DM.

Hepatoprotective impact of Nigella sativa silver nanocomposite against genotoxicity, oxidative stress, and inflammation induced by thioacetamide

Protection from liver damage and the repercussion of that harm is thought to be crucial for reducing the number of deaths each year. This work was developed to evaluate the possible role of silver nanocomposite prepared using Nigella sativa (N. sativa) aqueous extract against the hepatic damage brought on by thioacetamide (TAA), with particular attention to how they affect the NF-κβ, TNF-α, IL-1β, and COX-2 signaling pathways. There were seven groups of male Wistar rats used as follows: control, saline, N. sativa aqueous extract (NSAE; 200 mg/kg/d), N. sativa silver nanocomposite (NS-AgNC; 0.25 mg/kg/d), TAA (100 mg/kg; thrice weekly), NSAE + TTA, and NS-AgNC + TAA, respectively. The experiment continued for six weeks. The results showed that NS-AgNPs significantly enhanced liver functions (p<0.05) (albumin, ALP, LDH, AST, total protein, ALT, and globulin) and oxidant/antioxidant biomarkers (p<0.05) (H2O2, MDA, PCC, NO, SOD, CAT, GPx, GR, GST and, GSH), contrasted with TAA group. Moreover, a significant (p<0.05) downregulation of the gene expressions (COX-2, TNF-α, IL-1β, and NF-κβ) was also achieved by using silver nanocomposite therapy. These findings have been supported by histological analysis. Collectively, NS-AgNC exhibits more prominent and well-recognized protective impacts than NSAE in modulating the anti-inflammatory, genotoxicity and oxidative stress effects against TAA-induced liver injuries.

Enhanced Expression of p53 and Suppression of PI3K/Akt/mTOR by Three Red Sea Algal Extracts: Insights on Their Composition by LC-MS-Based Metabolic Profiling and Molecular Networking

Brown algae comprise up to 2000 species with wide dissemination in temperate zones. A comprehensive untargeted metabolic profiling guided by molecular networking of three uninvestigated Red-Sea-derived brown algae, namely Sirophysalis trinodis, Polycladia myrica, and Turbinaria triquetra, led to the identification of over 115 metabolites categorized as glycerolipids, fatty acids, sterol lipids, sphingolipids, and phospholipids. The three algae exhibited low-to-moderate antioxidant capacity using DPPH and ABTS assays. Preliminary in vitro antiproliferative studies showed that the algal extracts displayed high cytotoxic activity against a panel of cancer cell lines. The most potent activity was recorded against MCF-7 with IC₅₀ values of 51.37 ± 1.19, 63.44 ± 1.13, and 59.70 ± 1.22 µg/mL for S. trinodis, P. myrica, and T. triquetra, respectively. The cytotoxicity of the algae was selective to MCF-7 without showing notable effects on the proliferation of normal human WISH cells. Morphological studies revealed that the algae caused cell shrinkage, increased cellular debris, triggered detachment, cell rounding, and cytoplasmic condensation in MCF-7 cancer cells. Mechanistic investigations using flow cytometry, qPCR, and Western blot showed that the algae induced apoptosis, initiated cell cycle arrest in the sub-G₀/G₁ phase, and inhibited the proliferation of cancer cells via increasing mRNA and protein expression of p53, while reducing the expression of PI3K, Akt, and mTOR.

Transitioning single-cell genomics into the clinic

The use of genomics is firmly established in clinical practice, resulting in innovations across a wide range of disciplines such as genetic screening, rare disease diagnosis and molecularly guided therapy choice. This new field of genomic medicine has led to improvements in patient outcomes. However, most clinical applications of genomics rely on information generated from bulk approaches, which do not directly capture the genomic variation that underlies cellular heterogeneity. With the advent of single-cell technologies, research is rapidly uncovering how genomic data at cellular resolution can be used to understand disease pathology and mechanisms. Both DNA-based and RNA-based single-cell technologies have the potential to improve existing clinical applications and open new application spaces for genomics in clinical practice, with oncology, immunology and haematology poised for initial adoption. However, challenges in translating cellular genomics from research to a clinical setting must first be overcome.

Design, synthesis and molecular docking of novel substituted azepines as inhibitors of PI3K/Akt/TSC2/mTOR signaling pathway in colorectal carcinoma

A series of novel substituted azepines (2-7) was synthesized using both traditional and ultrasonic techniques. The efficiency of the reaction rate and yield was improved by sonication technique. We identified the newly synthesized compounds based on their melting points, elemental analyses, and spectral data. Human cancers are regulated mainly by the phosphatidylinositol 3-kinase/protein kinases B (PI3K/Akt) pathway, and its abnormal activation is linked to carcinogenesis, and angiogenesis. Using in-silico studies, we evaluated the ability of all the novel substituted diazepines and oxazepines to prevent cancer growth and metastasis by targeting the PI3K/Akt signaling pathway. Based on our findings, compounds 4a and 7a were chosen for in-vitro testing as they ranked via molecular docking the highest binding energies of -10.9, -10.3, -10.6, and -10.4 kcal/mol respectively. Compounds 4a and 7a displayed significant cytotoxicity on Caco-2 colorectal cancer cells with IC₅₀ values of 8.445 ± 2.26 and 33.04 ± 2.06 μM, respectively. Additionally, they considerably suppressed the PI3K/Akt proteins and generated reactive oxygen species (ROS), which increased p53 and Bax, decreased Bcl-₂ levels, and arrested the cell cycle at sub-G0/G1 phase. We also observed a remarkable overexpression of the Tuberous Sclerosis Complex 2 (TSC2) gene, an inhibitor of the mammalian target of rapamycin (mTOR). These results showed that compounds 4a and 7a obeyed Lipinski's rule of five and might be potential cancer treatment scaffolds by preventing metastasis and proliferation via blocking the PI3K/Akt/TSC2/m-TOR signaling pathway. This supports our hypothesis that diazepine 4a and oxazepine 7a are promising drug candidates for colorectal cancer.

Concerted regulation of OPG/RANKL/ NF‑κB/MMP-13 trajectories contribute to ameliorative capability of prodigiosin and/or low dose γ-radiation against adjuvant- induced arthritis in rats

BACKGROUND

Prodigiosin (PDG) is a microbial red dye with antioxidant and anti-inflammatory properties, although its effect on rheumatoid arthritis (RA) remains uncertain. Also, multiple doses of low dose γ- radiation (LDR) have been observed to be as a successful intervention for RA. Thus, the purpose of this study was to investigate the ameliorative potential of PDG and/or LDR on adjuvant-induced arthritis (AIA) in rats.

METHODS

The anti-inflammatory and anti-arthritic effects of PDG and/or LDR were examined in vitro and in vivo, respectively. In the AIA model, the arthritic indexes, paw swelling degrees, body weight gain, and histopathological assessment in AIA rats were assayed. The impact of PDG (200 µg/kg; p.o) and/or LDR (0.5 Gy) on the levels of pro- and anti-inflammatory cytokines (IL-1β, TNF-α, IL-6, IL-18, IL-17A, and IL-10) as well as the regulation of osteoprotegrin (OPG)/ receptor activator of nuclear factor κB ligand (RANKL)/ nuclear factor-κB (NF-κB)/MMP-13 pathways was determined. Methotrexate (MTX; 0.05 mg/kg; twice/week, i.p) was administered concurrently as a standard anti-arthritic drug.

RESULTS

PDG and/or LDR markedly diminished the arthritic indexes, paw edema, weigh loss in AIA rats, alleviated the pathological alterations in joints, reduced the levels of pro-inflammatory cytokines IL-1β, TNF-α, IL-6, IL-18, IL-17A, and RANKL in serum and synovial tissues, while increasing anti-inflammatory cytokines IL-10 and OPG levels. Moreover, PDG and/or LDR down-regulated the expression of RANKL, NF-κBp65, MMP13, caspase-3, and decreased the RANKL/OPG ratio, whereas OPG and collagen II were enhanced in synovial tissues.

CONCLUSION

PDG and/or LDR exhibited obvious anti-RA activity on AIA.

Newly Synthesized Pyrazolinone Chalcones as Anticancer Agents via Inhibiting the PI3K/Akt/ERK1/2 Signaling Pathway

A series of novel pyrazolinone chalcones 3-9 have been synthesized through the condensation of azo pyrazolinone derivatives with various aromatic aldehydes. Spectroscopic techniques and elemental analysis have both corroborated this. Furthermore, all compounds were screened in silico for their ability to inhibit cancer proliferation and metastasis by targeting the PI3K/Akt signaling pathway. This inhibitory pathway might be an efficient approach for the death of cancer cells, angiogenesis, and metastasis prevention. Our results indicated that only compound 6b was the top-ranked. It demonstrated the highest binding energies of -11.1 and -10.7 kcal/mol against the target proteins PI3K and Akt, respectively; thus, it was chosen for in vitro studies. Compound 6b exhibited the most effective cytotoxic impact against the Caco cell line with IC₅₀ of 23.34 ± 0.14 μM. Furthermore, it showed significant inhibition of PI3K/Akt proteins and oxidative stress, leading to elevated Bax and p53 expression, reduced Bcl_-2 expression, and triggered cell cycle arrest at the sub-G0/G1 phase. Additionally, it showed significant downregulation of the Raf-1 gene, leading to ERK1/2 protein inhibition. These findings demonstrate that compound 6b obeyed Lipinski's rule of five and might be used as a favored scaffold for cancer treatment by inhibiting proliferation and metastasis via inhibition of the PI3K/Akt and Raf-1/ERK1/2 signaling pathways.

Comparative LC-LTQ-MS-MS Analysis of the Leaf Extracts of Lantana camara and Lantana montevidensis Growing in Egypt with Insights into Their Antioxidant, Anti-Inflammatory, and Cytotoxic Activities

Lantana camara L. and Lantana montevidensis Briq. (F. Verbenaceae) are invasive ornamental weeds native to the tropical regions of Africa and America. The leaves of both species have been traditionally used as infusions for treating fever, rheumatism, and cancer. LC-MS-MS-guided profiling of the methanolic extracts of the leaves of L. camara and L. montevidensis growing in Egypt led to the putative identification of 59 compounds belonging to terpenoids, flavonoids, iridoid glycosides, phenolic acids, and their derivatives. The in-vitro antioxidants and anti-inflammatory and anticancer activities of the two extracts were investigated. L. camara and L. montevidensis inhibited DPPH^• (IC₅₀ = 34.01 ± 1.32 and 47.43 ± 1.74 µg/mL), ABTS⁺ (IC₅₀ = 30.73 ± 1.42 and 40.37 ± 1.51 µg/mL), and superoxide anion (IC₅₀ = 1.57 ± 0.19 and 1.31 ± 0.14 μg/mL) free radicals. A potent anti-inflammatory effect was observed for both species through the inhibition of elastase release in fMLF/CB-induced human neutrophils (IC₅₀ = 2.40 ± 0.16 and 1.90 ± 0.07 μg/mL). The extracts showed significant cytotoxic activity against a panel of cancer cell lines with the most potent activity against Caco cells (IC₅₀ = 45.65 ± 1.64 and 40.67 ± 1.52 µg/mL for L. camara and L. montevidensis, respectively). Western blotting supported by FACS analysis revealed that the extracts inhibited cancer cell proliferation, reduced metastasis, and induced apoptosis resulting in cell cycle arrest. This was achieved via increasing mRNA and protein expressions of p53 and GSK-3β as well as decreasing the expression of PI3K, Akt, and cyclin D1.

Quercetin mitigates rheumatoid arthritis by inhibiting adenosine deaminase in rats

Rheumatoid arthritis (RA) is a chronic inflammatory joint disease characterized by synovial proliferation and bone destruction. Adenosine deaminase (ADA) is a key inflammatory enzyme that increases joint stiffness and pain in RA. In this study, we evaluated the in-silico, and in vivo inhibitory effect of quercetin isolated from Egyptian Fenugreek on ADA enzyme activity. We also determined the combinatorial effect of quercetin on methotrexate mediated anti-inflammatory efficacy and toxicity. In-silico molecular docking was conducted and confirmed in an in vivo RA rat model. The results showed that the inhibition constant of quercetin on joint ADA by docking and in-vitro was 61.9 and 55.5 mM, respectively. Therefore, quercetin exhibits anti-inflammatory effect in a rat RA model as evidenced by reducing the specific activity of ADA in joint tissues, lower jaw volume, enhance body weight, downregulate ADA gene expression, reduce levels of RA cytokines interleukin-1^β, interleukin-6, tumor necrosis factor-α, also, rheumatoid factor, C-reactive protein, and anti-cyclic citrullinated peptide RA biomarker levels. These findings demonstrate that the purified quercetin has a promising anti-inflammatory effect against RA disease through its inhibitory effects on the ADA enzyme. Furthermore, isolated quercetin improved the anti-inflammatory efficacy of methotrexate, reduced its toxic effects by increasing antioxidant enzymes and reducing oxidative stress.

Prospective Monitoring of Circulating Epithelial Tumor Cells (CETC) Reveals Changes in Gene Expression during Adjuvant Radiotherapy of Breast Cancer Patients

Circulating epithelial tumor cells (CETC) are considered to be responsible for the formation of metastases. Therefore, their importance as prognostic and/or predictive markers in breast cancer is being intensively investigated. Here, the reliability of single cell expression analyses in isolated and collected CETC from whole blood samples of patients with early-stage breast cancer before and after radiotherapy (RT) using the maintrac^® method was investigated. Single-cell expression analyses were performed with qRT-PCR on a panel of selected genes: GAPDH, EpCAM, NANOG, Bcl-2, TLR 4, COX-2, PIK3CA, Her-2/neu, Vimentin, c-Met, Ki-67. In all patients, viable CETC were detected prior to and at the end of radiotherapy. In 7 of the 9 (77.8%) subjects examined, the CETC number at the end of the radiotherapy series was higher than before. The majority of genes analyzed showed increased expression after completion of radiotherapy compared to baseline. Procedures and methods used in this pilot study proved to be feasible. The method is suitable for further investigation of the underlying molecular biological mechanisms occurring in cells surviving radiotherapy and possibly the development of radiation resistance.

New Amino Acid Schiff Bases as Anticancer Agents via Potential Mitochondrial Complex I-Associated Hexokinase Inhibition and Targeting AMP-Protein Kinases/mTOR Signaling Pathway

Two series of novel amino acid Schiff base ligands containing heterocyclic moieties, such as quinazolinone 3–11 and indole 12–20 were successfully synthesized and confirmed by spectroscopic techniques and elemental analysis. Furthermore, all compounds were investigated in silico for their ability to inhibit mitochondrial NADH: ubiquinone oxidoreductase (complex I) by targeting the AMPK/mTOR signaling pathway and inhibiting hexokinase, a key glycolytic enzyme to prevent the Warburg effect in cancer cells. This inhibitory pathway may be an effective strategy to cause cancer cell death due to an insufficient amount of ATP. Our results revealed that, out of 18 compounds, two (11 and 20) were top-ranked as they exhibited the highest binding energies of −8.8, −13.0, −7.9, and −10.0 kcal/mol in the docking analysis, so they were then selected for in vitro assessment. Compound 11 promoted the best cytotoxic effect on MCF-7 with IC₅₀ = 64.05 ± 0.14 μg/mL (0.135 mM) while compound 20 exhibited the best cytotoxic effect on MDA-231 with IC₅₀ = 46.29 ± 0.09 μg/mL (0.166 mM) Compounds 11 and 20 showed significant activation of AMPK protein and oxidative stress, which led to elevated expression of p53 and Bax, reduced Bcl-2 expression, and caused cell cycle arrest at the sub-G₀/G₁ phase. Moreover, compounds 11 and 20 showed significant inhibition of the mTOR protein, which led to the activation of aerobic glycolysis for survival. This alternative pathway was also blocked as compounds 11 and 20 showed significant inhibitory effects on the hexokinase enzyme. These findings demonstrate that compounds 11 and 20 obeyed Lipinski’s rule of five and could be used as privileged scaffolds for cancer therapy via their potential inhibition of mitochondrial complex I-associated hexokinase.

Lab-on-a-Chip Platforms for Biophysical Studies of Cancer with Single-Cell Resolution

Recent cancer research has more strongly emphasized the biophysical aspects of tumor development, progression, and microenvironment. In addition to genetic modifications and mutations in cancer cells, it is now well accepted that the physical properties of cancer cells such as stiffness, electrical impedance, and refractive index vary with tumor progression and can identify a malignant phenotype. Moreover, cancer heterogeneity renders population-based characterization techniques inadequate, as individual cellular features are lost in the average. Hence, platforms for fast and accurate characterization of biophysical properties of cancer cells at the single-cell level are required. Here, we highlight some of the recent advances in the field of cancer biophysics and the development of lab-on-a-chip platforms for single-cell biophysical analyses of cancer cells.

Electrochemical Genetic Profiling of Single Cancer Cells

Recent understandings in the development and spread of cancer have led to the realization of novel single cell analysis platforms focused on circulating tumor cells (CTCs). A simple, rapid, and inexpensive analytical platform capable of providing genetic information on these rare cells is highly desirable to support clinicians and researchers alike to either support the selection or adjustment of therapy or provide fundamental insights into cell function and cancer progression mechanisms. We report on the genetic profiling of single cancer cells, exploiting a combination of multiplex ligation-dependent probe amplification (MLPA) and electrochemical detection. Cells were isolated using laser capture and lysed, and the mRNA was extracted and transcribed into DNA. Seven markers were amplified by MLPA, which allows for the simultaneous amplification of multiple targets with a single primer pair, using MLPA probes containing unique barcode sequences. Capture probes complementary to each of these barcode sequences were immobilized on a printed circuit board (PCB) manufactured electrode array and exposed to single-stranded MLPA products and subsequently to a single stranded DNA reporter probe bearing a HRP molecule, followed by substrate addition and fast electrochemical pulse amperometric detection. We present a simple, rapid, flexible, and inexpensive approach for the simultaneous quantification of multiple breast cancer related mRNA markers, with single tumor cell sensitivity.

Single-Cell Transcriptomics Bioinformatics and Computational Challenges

The emerging single-cell RNA-Seq (scRNA-Seq) technology holds the promise to revolutionize our understanding of diseases and associated biological processes at an unprecedented resolution. It opens the door to reveal intercellular heterogeneity and has been employed to a variety of applications, ranging from characterizing cancer cells subpopulations to elucidating tumor resistance mechanisms. Parallel to improving experimental protocols to deal with technological issues, deriving new analytical methods to interpret the complexity in scRNA-Seq data is just as challenging. Here, we review current state-of-the-art bioinformatics tools and methods for scRNA-Seq analysis, as well as addressing some critical analytical challenges that the field faces.