Investigating the Physicochemical Properties of B12X122− (X = H, F, Cl, Br, I)

This thesis focuses on B12X122– (X = H, F, Cl, Br, I) experimentally and computationally to understand the fundamental behaviour of this multiply charged anion (MCA) in the gas and solution phases. The thesis explores three different phases of B12X122–: gas phase, micro-solvated phase, and solution phase. This allows for the breakdown of the phenomena affecting the stability of the MCA in solution into the MCAs geometric and electronic properties and solvent-binding interactions. The first study investigates the dynamic clustering behaviour between B12X122– (X = H, F) and solvent molecules in the gas phase. Differential mobility spectrometry (DMS) is used to induce micro-solvation states of the MCA as an approach to bridge the gas and solution phase properties. DMS is coupled with computational studies to draw connections from the microsolvation states and solvent interaction potentials. This will provide a means to investigate the dominance of the effects of the individual interactions on stability of the dianion. The second project explores the bare anion of B12X122– (X = H, F, Cl, Br, I) in the gas phase. Photoelectron spectroscopy (PES) is simulated and compared with the experimental data for a great understanding of the vibronic transitions and electronic structure of the dianion and its monoanionic counterpart. Geometric distortions after electron detachment are also simulated to determine geometric effects on the stability of the B12X122–. Additionally, various computational methods are explored to investigate their accuracy in predicting the MCA’s electronic structure. The solution phase behaviour of B12F122– is explored in the final chapter, coupling the findings with the knowledge gained in the first two projects. The solvated B12F122–aq is studied using femtosecond pump probe absorption spectroscopy to investigate the role of charge-transfer-to solvent in stabilizing the MCA. The investigations detailed in this thesis reveal the intricacies of the electronic and geometric structures of the species in the gas and solution phases. It is concluded that as repulsive Coulombic factors along with solvent interactions determine the stability of the ground and electronic excited states of the MCA in solution phase

Ligand Specificity and Affinity in the Sulforhodamine B Binding RNA Aptamer

The final publication is available at Elsevier via http://dx.doi.org/10.1016/j.bbrc.2020.06.056. © 2020. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/Binding affinity and selectivity are critical properties of aptamers that must be optimized for any application. The sulforhodamine B binding RNA aptamer (SRB‐2) is a somewhat promiscuous aptamer that can bind ligands that vary markedly in shape, size and charge. Here we categorize potential ligands based on their binding mode and structural characteristics required for high affinity and selectivity. Several known and potential ligands of SRB‐2 were screened for binding affinity using LSPR, ITC and NMR spectroscopy. The study shows that rhodamine B has the ideal structural and electrostatic properties for selective and high‐affinity binding of the SRB‐2 aptamer.NSERC Discovery Grant 30345

Characteristics of interval gastric neoplasms detected within two years after negative screening endoscopy among Koreans

Background In Korea, where gastric cancer is highly prevalent, biennial endoscopy is recommended among individuals over 40. Even under regular screening, some are still diagnosed at advanced stages. We aimed to identify characteristics of interval gastric neoplasms (IGNs) with rapid progression. Results Newly-diagnosed gastric neoplasms detected in screening endoscopy between January 2004 and May 2016 were reviewed. Among them, those who had previous endoscopy within 2 years were enrolled. Endoscopic findings, family history of gastric cancer, smoking, and H. pylori status were analysed. Totally, 297 IGN cases were enrolled. Among them, 246 were endoscopically treatable IGN (ET-IGN) and 51 were endoscopically untreatable IGNs (EUT-IGN) by the expanded criteria for endoscopic submucosal dissection. Among EUT-IGNs, 78% were undifferentiated cancers (40/51) and 33% showed submucosal invasion (13/40). They were median 2.0 cm in size and more commonly located in the proximal stomach than ET-IGNs (70.6% vs. 41.9%, p < 0.001). EUT-IGN was independently related with age < 60 (OR, 2.09; 95%CI, 1.03–4.26, p = 0.042), H. pylori (OR, 2.81; 95%CI, 1.20–6.63, p = 0.018), and absent/mild gastric atrophy (OR, 2.67; 95%CI, 1.25–5.72, p = 0.011). Overall and disease-specific survival were not significantly different between the two groups, however EUT-IGN tended to have short disease-specific survival (overall survival, p = 0.143; disease-specific survival, p = 0.083). Conclusions Uniform screening endoscopy with two-year interval seems not enough for rapid-growing gastric neoplasms, such as undifferentiated cancers. They tended to develop in adults younger than 60 with H. pylori infection without severe gastric atrophy. More meticulous screening, especially for proximal lesions is warranted for adults younger than 60 with H. pylori infection before development of gastric atrophy

Steatocystoma Multiplex Confined to the Scalp with Concurrent Alopecia

Steatocystoma multiplex (SM) is an uncommon disorder of the pilosebaceous unit characterized by the development of numerous sebum-containing dermal cysts which rarely involves the scalp. Here, we report a case of a 50-year-old man with multiple cystic nodules and alopecic patches on his scalp. On histopathological examination, the folded cyst was found to be lined by stratified squamous epithelium, while flattened sebaceous gland cells were identified in the cystic wall. Pigment casts were present in the hair papillae and perifollicular regions, suggesting trichotillomania as a possible cause of the observed alopecia. This case appears to represent an unusual clinical manifestation of SM

Percutaneous aspiration of lumbar zygapophyseal joint synovial cyst under fluoroscopic guidance -A case report-

A 51-year-old man with a 1-month history of lower back pain and radiating pain visited to our pain clinic. A magnetic resonance imaging (MRI) scan demonstrated a cyst like mass at the level of the L4-5 interspace and compression of the thecal sac and the nerve root on the right side. We performed percutaneous needle aspiration of the lumbar zygapophyseal joint synovial cyst under fluoroscopic guidance. The patient felt an immediate relief of symptoms after the aspiration, and had no signs or symptoms of recurrence at the follow-up 6 months later. No demonstrable lesion was found in the 6 months follow-up MRI

Blood neurofilament light chain as a biomarker for monitoring and predicting paclitaxel-induced peripheral neuropathy in patients with gynecological cancers

ObjectiveWe aimed to evaluate the potential of serum neurofilament light chain (sNfL) and serum brain-derived neurotrophic factor (sBDNF) as reliable biomarkers for paclitaxel-induced peripheral neuropathy (PIPN).MethodsForty-eight patients with gynecologic cancer scheduled to undergo six cycles of paclitaxel-based chemotherapy at the National Cancer Center of Korea between September 2020 and January 2022 were prospectively assessed during and after chemotherapy.ResultsAt the end of the chemotherapy, 12 (25%) patients were classified as having grade 3 PIPN according to the National Cancer Institute-Common Toxicity Criteria. The sNfL levels increased during paclitaxel treatment in all patients. After two, four, and six cycles, patients with grade 3 PIPN exhibited higher mean sNfL levels than those in the 0–2 grade range (p = 0.004, p = 001, and p &lt; 0.001, respectively). For sNfL levels ≥ 124 pg/mL, after two cycles of chemotherapy, the sensitivity and specificity for predicting grade 3 PIPN at the end of treatment were 80% and 79%, respectively. Over the course of paclitaxel-based treatment, sBDNF levels continued to decrease regardless of the severity of PIPN. At the end of treatment and six months after chemotherapy, patients with grade 3 PIPN had lower sBDNF levels than those within the 0–2 grade range (p =0.037 and 0.02, respectively), and the patients in the latter group had better clinical symptoms six months after the end of treatment.ConclusionsThe sNfL levels during paclitaxel-based chemotherapy reflect ongoing neuroaxonal injury and serve as reliable biomarkers of PIPN severity. The sNfL levels during early treatment with paclitaxel might be prognostic indicators for PIPN progression. Low sBDNF levels 6 months after chemotherapy might adversely affect PIPN recovery