An Exopolysaccharide from the Cyanobacterium Arthrospira platensis May Utilize CH-π Bonding: A Review of the Isolation, Purification, and Chemical Structure of Calcium-Spirulan.

The CH-π bonding potential of a saccharide is determined primarily by the number of hydrogen atoms available for bonding and is reduced by side groups that interfere with the CH-π bond. Each hydrogen bond increases the total bond energy, while interfering hydroxyl groups and other side groups reduce the bond energy by repulsion. The disaccharide repeating units of Calcium-Spirulan (Ca-SP), a large exopolysaccharide sub fractionated from the supernatant of the cyanobacterium Arthrospira platensis, contain a unique monosaccharide that is completely devoid of hydroxyl groups and side groups on its entire beta surface, leaving five hydrogen atoms available for CH-π bonding in the planar conformation. While planar conformations of independent pyranose rings are rare-to-nonexistent, due to ring strain associated with that conformation, the binding site of a protein could provide the conformational energy needed to overcome that energy barrier. By enabling a planar conformation, a protein could also enable the sugar to form a novel 5-hydrogen CH-π bond configuration. One study of the anticoagulant property of Ca-SP shows that the molecule acts as an activator of Heparin Cofactor II (HC-II), boosting its anticoagulant kinetics by 104. In comparison, the longstanding anticoagulant drug Heparin boosts the HC-II kinetics by 103. The difference may be explained by this unique CH-π configuration. Here, we review current knowledge and experience on the isolation techniques, analytical methods, and chemical structures of Ca-SP. We emphasize a discussion of the CH-π bonding potential of this unique polysaccharide because it is a topic that has not yet been addressed. By introducing the topic of CH-π bonding to the cyanobacterial research community, this review may help to set the stage for further investigation of these unique molecules, their genetics, their biosynthetic pathways, their chemistry, and their biological functions.

Bis-sulfonamido-2-phenylbenzoxazoles Validate the GroES/EL Chaperone System as a Viable Antibiotic Target.

We recently reported on small-molecule inhibitors of the GroES/GroEL chaperone system as potential antibiotics against Escherichia coli and the ESKAPE pathogens but were unable to establish GroES/GroEL as the cellular target, leading to cell death. In this study, using two of our most potent bis-sulfonamido-2-phenylbenzoxazoles (PBZs), we established the binding site of the PBZ molecules using cryo-EM and found that GroEL was the cellular target responsible for the mode of action. Cryo-EM revealed that PBZ1587 binds at the GroEL ring-ring interface (RRI). A cellular reporter assay confirmed that PBZ1587 engaged GroEL in cells, but cellular rescue experiments showed potential off-target effects. This prompted us to explore a closely related analogue, PBZ1038, which is also bound to the RRI. Biochemical characterization showed potent inhibition of Gram-negative chaperonins but much lower potency of chaperonin from a Gram-positive organism, Enterococcus faecium. A cellular reporter assay showed that PBZ1038 also engaged GroEL in cells and that the cytotoxic phenotype could be rescued by a chromosomal copy of E. faecium GroEL/GroES or by expressing a recalcitrant RRI mutant. These data argue that PBZ1038's antimicrobial action is exerted through inhibition of GroES/GroEL, validating this chaperone system as an antibiotic target.

Granulomatous Inflammation of the Skull Base: A Rare Case of Mycobacterium tuberculosis in the United States.

The differential for an ill-defined, bone-destructive, granulomatous lesion of the skull base includes malignancy, as well as autoimmune and infectious processes. Suspicion for tuberculosis of the skull base in high-risk patients is particularly necessary given the difficulty to culture on standard cultures, need for specific and prolonged antibiotic therapy, and dire morbidity if not diagnosed and treated in a timely manner. Repeat biopsies and cultures were necessary to diagnose this case of Mycobacterium tuberculosis of the skull base after initial biopsy was non-diagnostic. Laryngoscope, 134:4023-4027, 2024.

Discovery of a Tunable Heterocyclic Electrophile 4-Chloro-pyrazolopyridine That Defines a Unique Subset of Ligandable Cysteines.

Electrophilic small molecules with novel reactivity are powerful tools that enable activity-based protein profiling and covalent inhibitor discovery. Here, we report a reactive heterocyclic scaffold, 4-chloro-pyrazolopyridine (CPzP) for selective modification of proteins via a nucleophilic aromatic substitution (SNAr) mechanism. Chemoproteomic profiling reveals that CPzPs engage cysteines within functionally diverse protein sites including ribosomal protein S5 (RPS5), inosine monophosphate dehydrogenase 2 (IMPDH2), and heat shock protein 60 (HSP60). Through the optimization of appended recognition elements, we demonstrate the utility of CPzP for covalent inhibition of prolyl endopeptidase (PREP) by targeting a noncatalytic active-site cysteine. This study suggests that the proteome reactivity of CPzPs can be modulated by both electronic and steric features of the ring system, providing a new tunable electrophile for applications in chemoproteomics and covalent inhibitor design.

Delayed Diagnosis of Ectopic Cushing Syndrome.

Here, we present the case of a 40-year-old man in whom the diagnosis of ectopic adrenocorticotropin (ACTH) syndrome went unrecognized despite evaluation by multiple providers until it was ultimately suspected by a nephrologist evaluating the patient for edema and weight gain. On urgent referral to endocrinology, screening for hypercortisolism was positive by both low-dose overnight dexamethasone suppression testing and 24-hour urinary free cortisol measurement. Plasma ACTH values confirmed ACTH-dependent Cushing syndrome. High-dose dexamethasone suppression testing was suggestive of ectopic ACTH syndrome. Inferior petrosal sinus sampling demonstrated no central-to-peripheral gradient, and 68Ga-DOTATATE scanning revealed an avid 1.2-cm left lung lesion. The suspected source of ectopic ACTH was resected and confirmed by histopathology, resulting in surgical cure. While many patients with Cushing syndrome have a delayed diagnosis, this case highlights the critical need to increase awareness of the signs and symptoms of hypercortisolism and to improve the understanding of appropriate screening tests among nonendocrine providers.

Comprehensive genomic profiling reveals molecular subsets of ASXL1-mutated myeloid neoplasms.

A large-scale genomic analysis of patients with ASXL1-mutated myeloid disease has not been performed to date. We reviewed comprehensive genomic profiling results from 6043 adults to characterize clinicopathologic features and co-mutation patterns by ASXL1 mutation status. ASXL1 mutations occurred in 1414 patients (23%). Mutation co-occurrence testing revealed strong co-occurrence (p < 0.01) between mutations in ASXL1 and nine genes (SRSF2, U2AF1, RUNX1, SETBP1, EZH2, STAG2, CUX1, CSF3R, CBL). Further analysis of patients with these co-mutations yielded several novel findings. Co-mutation patterns supported that ASXL1/SF3B1 co-mutation may be biologically distinct from ASXL1/non-SF3B1 spliceosome co-mutation. In AML, ASXL1/SRSF2 co-mutated patients frequently harbored STAG2 mutations (42%), which were dependent on the presence of both ASXL1 and SRSF2 mutation (p < 0.05). STAG2 and SETBP1 mutations were also exclusive in ASXL1/SRSF2 co-mutated patients and associated with divergent chronic myeloid phenotypes. Our findings support that certain multi-mutant genotypes may be biologically relevant in ASXL1-mutated myeloid disease.

Chemically induced partial unfolding of the multifunctional Apurinic/apyrimidinic endonuclease 1.

Targeting of the multifunctional enzyme apurinic/apyrimidinic endonuclease I/redox factor 1 (APE1) has produced small molecule inhibitors of both its endonuclease and redox activities. While one of the small molecules, the redox inhibitor APX3330, completed a Phase I clinical trial for solid tumors and a Phase II clinical trial for Diabetic Retinopathy/Diabetic Macular Edema, the mechanism of action for this drug has yet to be fully understood. Here, we demonstrate through HSQC NMR studies that APX3330 induces chemical shift perturbations (CSPs) of both surface and internal residues in a concentration-dependent manner, with a cluster of surface residues defining a small pocket on the opposite face from the endonuclease active site of APE1. Furthermore, APX3330 induces partial unfolding of APE1 as evidenced by a time-dependent loss of chemical shifts for approximately 35% of the residues within APE1 in the HSQC NMR spectrum. Notably, regions that are partially unfolded include adjacent strands within one of two beta sheets that comprise the core of APE1. One of the strands comprises residues near the N-terminal region and a second strand is contributed by the C-terminal region of APE1, which serves as a mitochondrial targeting sequence. These terminal regions converge within the pocket defined by the CSPs. In the presence of a duplex DNA substrate mimic, removal of excess APX3330 resulted in refolding of APE1. Our results are consistent with a reversible mechanism of partial unfolding of APE1 induced by the small molecule inhibitor, APX3330, defining a novel mechanism of inhibition.

A phase 2 study of neoadjuvant chemotherapy plus durvalumab in resectable locally advanced head and neck squamous cell carcinoma.

BACKGROUND: Patients with locally advanced head and neck squamous cell cancer (HNSCC) are treated with surgery followed by adjuvant (chemo) radiotherapy or definitive chemoradiation, but recurrence rates are high. Immune checkpoint blockade improves survival in patients with recurrent/metastatic HNSCC; however, the role of chemo-immunotherapy in the curative setting is not established. METHODS: This phase 2, single-arm, multicenter study evaluated neoadjuvant chemo-immunotherapy with carboplatin, nab-paclitaxel, and durvalumab in patients with resectable locally advanced HNSCC. The primary end point was a hypothesized pathologic complete response rate of 50%. After chemo-immunotherapy and surgical resection, patients received study-defined, pathologic risk adapted adjuvant therapy consisting of either durvalumab alone (low risk), involved field radiation plus weekly cisplatin and durvalumab (intermediate risk), or standard chemoradiation plus durvalumab (high risk). RESULTS: Between December 2017 and November 2021, 39 subjects were enrolled at three centers. Oral cavity was the most common primary site (69%). A total of 35 of 39 subjects underwent planned surgical resection; one subject had a delay in surgery due to treatment-related toxicity. The most common treatment-related adverse events were cytopenias, fatigue, and nausea. Post treatment imaging demonstrated an objective response rate of 57%. Pathologic complete response and major pathologic response were achieved in 29% and 49% of subjects who underwent planned surgery, respectively. The 1-year progression-free survival was 83.8% (95% confidence interval, 67.4%-92.4%). CONCLUSIONS: Neoadjuvant carboplatin, nab-paclitaxel, and durvalumab before surgical resection of HNSCC were safe and feasible. Although the primary end point was not met, encouraging rates of pathologic complete response and clinical to pathologic downstaging were observed.

ANCA vasculitis expands the spectrum of autoimmune manifestations of activated PI3 kinase δ syndrome.

Activated phosphoinositide 3-kinase δ syndrome (APDS) is a combined immunodeficiency with a broad clinical phenotype, including not only an increased propensity for sinopulmonary and herpesviruses infections but also immune dysregulation, such as benign lymphoproliferation, autoimmunity, and malignancy. Autoimmune complications are increasingly recognized as initial presenting features of immune dysregulation in inborn errors of immunity (IEIs), including APDS, so awareness of the spectrum of autoimmune features inherit within these disorders is critical. We present here a patient vignette to highlight cutaneous antineutrophil cytoplasmic antibody (ANCA) vasculitis as an underrecognized autoimmune manifestation of APDS. The genetic defects underlying APDS result in increased PI3Kδ signaling with aberrant downstream signaling pathways and loss of B- and/or T-cell immunologic tolerance mechanisms, which promote the development of autoimmunity. An understanding of the molecular pathways and mechanisms that lead to immune dysregulation in APDS has allowed for significant advancements in the development of precision-medicine therapeutics, such as leniolisib, to reduce the morbidity and mortality for these patients. Overall, this case and review highlight the need to maintain a high index of suspicion for IEIs, such as APDS, in those presenting with autoimmunity in combination with a dysregulated immune phenotype for prompt diagnosis and targeted intervention.

Anatomic Acromioclavicular Joint Reconstruction with and without Acromioclavicular Ligament Reconstruction: A Comparative Biomechanical Study.

Background: The purpose of this study was to determine if adding a reconstructed superior acromioclavicular (AC) joint ligament adds significant biomechanical stability to the AC joint over anatomic coracoclavicular (CC) ligament reconstruction alone. Methods: Fourteen cadaver shoulders were used for the comparison of biomechanical stability among the anatomic CC ligament reconstruction alone, CC and AC ligament reconstruction, and the intact groups by measuring the displacement under cyclic loads. A load to failure test was then performed in the vertical direction at a loading rate of 2 mm /sec to determine surgical-repair joints' tolerance to the maximum failure load. Results: The average peak-to-peak displacement induced by cyclic load in the sagittal axis and vertical axis direction was not significantly different between CC ligament reconstruction, CC and AC ligament reconstruction, and intact groups. The maximum failure load for the CC reconstruction (224.9 ± 91.8 N (Mean ± SEM)) was lower than CC/AC reconstruction groups (326.2 ± 123.3 N). The CC/AC reconstruction group failed at a significantly higher load (t test, p = 0.016) than the CC reconstruction group. Conclusion: CC/AC reconstruction surgical technique yielded a better shoulder stability than CC ligament alone reconstruction that may better maintain reduction of the AC joint.Level of Evidence: Level II.

Granulomatosis With Polyangiitis Presenting as an Infratemporal Fossa Mass.

Granulomatosis with polyangiitis is a rare autoimmune disease that affects small to medium-sized blood vessels throughout the body. Here, we present a case of an infratemporal mass that was the result of granulomatosis with polyangiitis. A 51-year-old male presented to the emergency department due to right cheek and facial pain that he had been experiencing for 2 to 3 months. An MRI revealed a mass within the right infratemporal and pterygopalatine fossae extending into the inferior right orbital fissure along the maxillary division of the trigeminal nerve (V2) and the vidian nerve causing concern for malignancy. Histology from an endoscopic biopsy demonstrated multiple arteries with luminal obliteration with non-necrotizing granulomas. The patient was started on steroids and immunosuppressive therapy, which improved his symptoms and decreased the size of the residual mass. This case illustrates the need for laboratory testing, imaging, and biopsy of the involved tissue in cases where GPA is suspected to prevent treatment delays that could lead to the destruction of vital organs.

Bis-aryl-α,ß-unsaturated ketone (ABK) chaperonin inhibitors exhibit selective cytotoxicity to colorectal cancer cells that correlates with levels of aberrant HSP60 in the cytosol.

While many studies have established the importance of protein homeostasis in tumor progression, little effort has been made to examine the therapeutic potential of targeting the HSP60 chaperonin system. In healthy cells, HSP60 is localized to the mitochondrial matrix; however, emerging evidence indicates HSP60 can be over-expressed and mis-localized to the cytosol of cancer cells, which is hypothesized to promote tumor cell survival and proliferation. This opens a potential avenue to selectively target the aberrant HSP60 in the cytosol as a chemotherapeutic strategy. In the present work, we examined a series of bis-aryl-α,ß-unsaturated ketone (ABK) HSP60 inhibitors for their ability to selectively target cancerous vs non-cancerous colon and intestine cells. We found that lead analogs inhibited migration and clonogenicity of cancer cells, with cytotoxicity correlating with the level of aberrant HSP60 in the cytosol.

Manipulating chromatin architecture in C. elegans.

BACKGROUND: Nucleosome-mediated chromatin compaction has a direct effect on the accessibility of trans-acting activators and repressors to DNA targets and serves as a primary regulatory agent of genetic expression. Understanding the nature and dynamics of chromatin is fundamental to elucidating the mechanisms and factors that epigenetically regulate gene expression. Previous work has shown that there are three types of canonical sequences that strongly regulate nucleosome positioning and thus chromatin accessibility: putative nucleosome-positioning elements, putative nucleosome-repelling sequences, and homopolymeric runs of A/T. It is postulated that these elements can be used to remodel chromatin in C. elegans. Here we show the utility of such elements in vivo, and the extreme efficacy of a newly discovered repelling sequence, PRS-322. RESULTS: In this work, we show that it is possible to manipulate nucleosome positioning in C. elegans solely using canonical and putative positioning sequences. We have not only tested previously described sequences such as the Widom 601, but also have tested additional nucleosome-positioning sequences: the Trifonov sequence, putative repelling sequence-322 (PRS-322), and various homopolymeric runs of A and T nucleotides. CONCLUSIONS: Using each of these types of putative nucleosome-positioning sequences, we demonstrate their ability to alter the nucleosome profile in C. elegans as evidenced by altered nucleosome occupancy and positioning in vivo. Additionally, we show the effect that PRS-322 has on nucleosome-repelling and chromatin remodeling.

On the Relationship between Diabetes and Obstructive Sleep Apnea: Evolution and Epigenetics.

This review offers an overview of the relationship between diabetes, obstructive sleep apnea (OSA), obesity, and heart disease. It then addresses evidence that the traditional understanding of this relationship is incomplete or misleading. In the process, there is a brief discussion of the evolutionary rationale for the development and retention of OSA in light of blood sugar dysregulation, as an adaptive mechanism in response to environmental stressors, followed by a brief overview of the general concepts of epigenetics. Finally, this paper presents the results of a literature search on the epigenetic marks and changes in gene expression found in OSA and diabetes. (While some of these marks will also correlate with obesity and heart disease, that is beyond the scope of this project). We conclude with an exploration of alternative explanations for the etiology of these interlinking diseases.

Allosteric differences dictate GroEL complementation of E. coli.

GroES/GroEL is the only bacterial chaperone essential under all conditions, making it a potential antibiotic target. Rationally targeting ESKAPE GroES/GroEL as an antibiotic strategy necessitates studying their structure and function. Herein, we outline the structural similarities between Escherichia coli and ESKAPE GroES/GroEL and identify significant differences in intra- and inter-ring cooperativity, required in the refolding cycle of client polypeptides. Previously, we observed that one-half of ESKAPE GroES/GroEL family members could not support cell viability when each was individually expressed in GroES/GroEL-deficient E. coli cells. Cell viability was found to be dependent on the allosteric compatibility between ESKAPE and E. coli subunits within mixed (E. coli and ESKAPE) tetradecameric GroEL complexes. Interestingly, differences in allostery did not necessarily result in differences in refolding rate for a given homotetradecameric chaperonin. Characterization of ESKAPE GroEL allostery, ATPase, and refolding rates in this study will serve to inform future studies focused on inhibitor design and mechanism of action studies.

Proximal-end bias from in-vitro reconstituted nucleosomes and the result on downstream data analysis.

The most basic level of eukaryotic gene regulation is the presence or absence of nucleosomes on DNA regulatory elements. In an effort to elucidate in vivo nucleosome patterns, in vitro studies are frequently used. In vitro, short DNA fragments are more favorable for nucleosome formation, increasing the likelihood of nucleosome occupancy. This may in part result from the fact that nucleosomes prefer to form on the terminal ends of linear DNA. This phenomenon has the potential to bias in vitro reconstituted nucleosomes and skew results. If the ends of DNA fragments are known, the reads falling close to the ends are typically discarded. In this study we confirm the phenomenon of end bias of in vitro nucleosomes. We describe a method in which nearly identical libraries, with different known ends, are used to recover nucleosomes which form towards the terminal ends of fragmented DNA. Finally, we illustrate that although nucleosomes prefer to form on DNA ends, it does not appear to skew results or the interpretation thereof.

Bilineal evolution of a U2AF1-mutated clone associated with acquisition of distinct secondary mutations.

Rare hematologic malignancies display evidence of both myeloid and lymphoid differentiation. Here, we describe such a novel bilineal event discovered in an adult woman with B-lymphoblastic leukemia (BLL). At the time of BLL diagnosis, the patient had a normal karyotype and a bulk sequencing panel identified pathogenic variants in BCOR, EZH2, RUNX1, and U2AF1, a genotype more typical of myeloid neoplasia. Additionally, the patient was noted to have 3-year history of cytopenias, and morphologic dyspoiesis was noted on post-treatment samples, raising the possibility of an antecedent hematologic disorder. To investigate the clonal architecture of her disease, we performed targeted sequencing on fractionated samples enriched for either B-lymphoblasts or circulating granulocytes. These studies revealed a truncal founder mutation in the spliceosome gene U2AF1 in both fractions, while distinct secondary mutations were present only in B-lymphoblasts (BCOR, NRAS) or myeloid cells (ASXL1, EZH2, RUNX1). These results indicate that both processes evolved from a common U2AF1-mutated precursor, which then acquired additional mutations during a process of divergent evolution and bilineal differentiation. Our findings highlight an atypical mechanism of BLL leukemogenesis and demonstrate the potential utility of fractionated sequencing in the characterization of acute leukemia.

Exploiting the HSP60/10 chaperonin system as a chemotherapeutic target for colorectal cancer.

Over the past few decades, an increasing variety of molecular chaperones have been investigated for their role in tumorigenesis and as potential chemotherapeutic targets; however, the 60 kDa Heat Shock Protein (HSP60), along with its HSP10 co-chaperone, have received little attention in this regard. In the present study, we investigated two series of our previously developed inhibitors of the bacterial homolog of HSP60/10, called GroEL/ES, for their selective cytotoxicity to cancerous over non-cancerous colorectal cells. We further developed a third "hybrid" series of analogs to identify new candidates with superior properties than the two parent scaffolds. Using a series of well-established HSP60/10 biochemical screens and cell-viability assays, we identified 24 inhibitors (14%) that exhibited > 3-fold selectivity for targeting colorectal cancer over non-cancerous cells. Notably, cell viability EC50 results correlated with the relative expression of HSP60 in the mitochondria, suggesting a potential for this HSP60-targeting chemotherapeutic strategy as emerging evidence indicates that HSP60 is up-regulated in colorectal cancer tumors. Further examination of five lead candidates indicated their ability to inhibit the clonogenicity and migration of colorectal cancer cells. These promising results are the most thorough analysis and first reported instance of HSP60/10 inhibitors being able to selectively target colorectal cancer cells and highlight the potential of the HSP60/10 chaperonin system as a viable chemotherapeutic target.

Autoimmune Cytopenia as an Early and Initial Presenting Manifestation in Activated PI3 Kinase Delta Syndrome: Case Report and Review.

Activated PI3 kinase delta syndrome (APDS) is a combined immunodeficiency characterized by recurrent sinopulmonary infections, increased risk of herpesvirus infections, lymphoproliferation, autoimmunity, and increased risk of lymphoid malignancies. Gain-of-function mutations in PIK3CD and PIK3R1 result in increased phosphoinositide-3-kinase-delta activity which causes hyperactivation of lymphocytes and abnormal development and activation of T and B cells. Cytopenias are the most common autoimmune process occurring in patients with APDS and typically occur as a later manifestation of the disease. Here we present a female patient with an early autoimmune hemolytic anemia, hepatosplenomegaly, and frequent infections presenting in infancy, followed by development of significant lymphadenopathy before her diagnosis with APDS type 1. She had significant improvement in her infectious history with immunoglobulin replacement, and control of autoimmune hemolytic anemia with initiation of sirolimus after her diagnosis with APDS type 1. We utilize this case to review the literature on APDS and present the novel finding of early-onset autoimmune disease in the setting of APDS. Autoimmune cytopenias are seen in many primary immunodeficiencies, and workup of autoimmune cytopenias in young patients should include evaluation for underlying immune disorder.