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jaehee lee

    jaehee lee

    Hemoptysis is a common cause of emergency department (ED) visits. There is little data about the role of systemic hypertension as a cause of hemoptysis. The aim of this study was to evaluate the association between systemic blood pressure... more
    Hemoptysis is a common cause of emergency department (ED) visits. There is little data about the role of systemic hypertension as a cause of hemoptysis. The aim of this study was to evaluate the association between systemic blood pressure and the unknown etiology of hemoptysis. This retrospective study included consecutive patients who visited the ED owing to hemoptysis and underwent a chest computed tomography between January 2011 and June 2021. Details of the initial blood pressure at the ED visit were compared between two groups with identified and unidentified causes of hemoptysis. In total, 1105 adult patients were included. The etiology of hemoptysis was identified in 1042 patients (94.3%) and remained unidentified in 63 patients (5.7%). The percentage of patients with severe hypertension was significantly higher in patients with unidentified causes of hemoptysis than in those with identified causes (35% vs. 11%, p < 0.001). In multivariate analysis, age, ever-smoker, and i...
    Abstract To describe the clinical and demographic characteristics of critically ill patients with COVID-19 in Daegu, South Korea, and to explore the risk factors for in-hospital mortality in these patients. Retrospective cohort study of... more
    Abstract To describe the clinical and demographic characteristics of critically ill patients with COVID-19 in Daegu, South Korea, and to explore the risk factors for in-hospital mortality in these patients. Retrospective cohort study of 110 critically ill patients with COVID-19 admitted to the ICU in Daegu, South Korea, between February 18 and April 5, 2020. The final date of follow-up was April 20, 2020. A total of 110 patient medical records were reviewed. The median age was 71 years (interquartile range [IQR] = 63–78 years). During the study period, 47 patients (42.7%) died in the hospital. The most common SARS-CoV-2 infection related complication was acute respiratory distress syndrome (ARDS) in 95 patients (86.4%). Of the 79 patients (71.8%) who received invasive mechanical ventilation, 46 (58.2%) received neuromuscular blockade injection, and 19 (24.1%) received ECMO treatment. All patients received antibiotic injection, 99 patients (90%) received hydroxychloroquine, 96 patients (87.3%) received lopinavir-ritonavir antiviral medication, and 14 patients (12.7%) received other antiviral agents, including darunavir-cobicistat and emtricitabine-tenofovir. In the multivariable logistic regression model, the odds ratio of in-hospital death was higher with APACHE II score (OR = 1.126; 95% CI = 1.014–1.252; P = .027). The in-hospital mortality rate of critically ill patients with COVID-19 was approximately 40%. Higher APACHE II score at admission was an independent risk factor for death in these patients.
    Drug administration should be considered a risk factor for venous thromboembolism (VTE) in younger healthy patients. We present a case of new‐onset pulmonary embolism (PE), possibly associated with excessive creatine supplement intake. A... more
    Drug administration should be considered a risk factor for venous thromboembolism (VTE) in younger healthy patients. We present a case of new‐onset pulmonary embolism (PE), possibly associated with excessive creatine supplement intake. A 24‐year‐old non‐smoker male presented to the emergency department with sudden‐onset dyspnoea and chest discomfort. Computed tomography pulmonary angiography and venography confirmed PE in the left and right pulmonary artery branches and a thrombus in the left popliteal vein. The patient had no family history of VTE, and other causes of thrombophilia were unlikely. He reported a recent increase in the intensity of his workouts and the dose of his creatine supplements in preparation for a bodybuilding competition. The creatine supplements likely promoted dehydration during intense workouts and profuse sweating. He received anticoagulation therapy, and the creatine supplements were discontinued. Creatine supplements should be used cautiously when there is a higher risk of becoming dehydrated.
    Parapneumonic effusions often complicate Mycoplasma pneumoniae (MP) pneumonia, contrary to the notion that they are a rare feature of MP infection. Increased research and evidence on MP parapneumonic effusions (MPPE) can help elucidate... more
    Parapneumonic effusions often complicate Mycoplasma pneumoniae (MP) pneumonia, contrary to the notion that they are a rare feature of MP infection. Increased research and evidence on MP parapneumonic effusions (MPPE) can help elucidate its clinical significance as one of the variable manifestations of MP infection. This article aims to summarize the existing literature about the clinical characteristics of MPPE in adults and discuss its diagnostic implications from the perspective of pleural fluid analysis. Approximately 20–25% of adult patients with MP pneumonia develop MPPE, and its frequency in children and adults seems to be similar. Although the pathogenesis of MPPE remains to be elucidated, MP-induced cell-mediated immune mechanisms might be partially associated with the development of MPPE. MPPE usually shows mononuclear leukocyte predominance with elevated adenosine deaminase (ADA) activity, similar to tuberculous pleural effusion (TPE). The degree of increase in pleural flu...
    Oncotarget24522www.impactjournals.com/oncotarget
    In this paper, a multiturn absolute serial encoder is designed for a space limited application such as robots using magnetic sensor instead of optical encoder. It is developed by integrating the ultra small magnetic detecting technique,... more
    In this paper, a multiturn absolute serial encoder is designed for a space limited application such as robots using magnetic sensor instead of optical encoder. It is developed by integrating the ultra small magnetic detecting technique, interpolation technique, and serial communication technique so that the sensor can have mimimum size. The usefulness of the sensor is verified with various tests.
    Lipoid pneumonia can develop from exposure to different types of oil, but occupational exposure is rare. A 58‐year‐old woman was referred to our hospital for patchy airspace opacities in the lungs with lower lobe predominance on chest... more
    Lipoid pneumonia can develop from exposure to different types of oil, but occupational exposure is rare. A 58‐year‐old woman was referred to our hospital for patchy airspace opacities in the lungs with lower lobe predominance on chest computed tomography. She was diagnosed with non‐Hodgkin's lymphoma seven years ago, but was in complete remission. She had mild cough and sputum, but no history of taking any lipid‐containing agents. The bronchoalveolar lavage fluid revealed lipid‐laden macrophages with Oil Red O staining, which led to the suspicion of lipoid pneumonia. Re‐evaluation of her personal history revealed that she was a dry‐cleaning worker who worked with organic solvent sprayers. Her condition was successfully managed with corticosteroids and avoidance of further occupational exposure to the substance. This rare case of occupational exogenous lipoid pneumonia in a dry‐cleaning worker suggests the importance of considering a patient's occupational history during diag...
    Patients with advanced chronic kidney disease (CKD) or who are on hemodialysis (HD) could have increased susceptibility to the 2019 coronavirus disease (COVID-19) given their pre-existing comorbidities, older age, compromised immune... more
    Patients with advanced chronic kidney disease (CKD) or who are on hemodialysis (HD) could have increased susceptibility to the 2019 coronavirus disease (COVID-19) given their pre-existing comorbidities, older age, compromised immune system, and regular visits to populated outpatient dialysis centers. This study included 14 consecutive patients on HD or with advanced CKD who initiated HD after being diagnosed with laboratory-confirmed COVID-19 from February to April 2020 in hospitals throughout Daegu, South Korea. The included patients, 42.9% of whom were men, had a mean age of 63.5 years. Four patients had a history of contact with a patient suffering from COVID-19. The most common symptom was cough (50.0%), followed by dyspnea (35.7%). The mean time from symptom onset to diagnosis and admission was 2.6 and 3.5 days, respectively. Patients exhibited lymphopenia and elevated inflammatory markers, including C-reactive protein and ferritin. Chest radiography findings showed pulmonary i...
    The effect of intubation timing on the prognosis of critically ill patients with coronavirus 2019 (COVID-19) is not yet well understood. We investigated whether early intubation is associated with the survival of COVID-19 patients with... more
    The effect of intubation timing on the prognosis of critically ill patients with coronavirus 2019 (COVID-19) is not yet well understood. We investigated whether early intubation is associated with the survival of COVID-19 patients with acute respiratory distress syndrome (ARDS). This multicenter, retrospective, observational study was done on 47 adult COVID-19 patients with ARDS who were admitted to the intensive care unit (ICU) in Daegu, Korea between February 17 and April 23, 2020. Clinical characteristics and in-hospital mortality were compared between the early intubation and initially non-intubated groups, and between the early and late intubation groups, respectively. Of the 47 patients studied, 23 (48.9%) were intubated on the day of meeting ARDS criteria (early intubation), while 24 (51.1%) were not initially intubated. Eight patients were never intubated during the in-hospital course. Median follow-up duration was 46 days, and 21 patients (44.7%) died in the hospital. No si...
    The outcome of coronavirus disease 2019 (COVID-19) is associated with organ damage; however, the information about the relationship between acute kidney injury (AKI) and COVID-19 is still rare. We evaluated the clinical features and... more
    The outcome of coronavirus disease 2019 (COVID-19) is associated with organ damage; however, the information about the relationship between acute kidney injury (AKI) and COVID-19 is still rare. We evaluated the clinical features and prognosis of COVID-19 patients with AKI according to the AKI severity. Medical data of hospitalized COVID-19 patients in two university-based hospitals during an outbreak in Daegu, South Korea, were retrospectively analyzed. AKI and its severity were defined according to the Acute Kidney Injury Network. Of the 164 hospitalized patients with COVID-19, 30 patients (18.3%) had AKI; 14, 4, and 12 patients had stage 1, 2, and 3, respectively. The median age was significantly higher in AKI patients than in non-AKI patients (75.5 vs. 67.0 years, p = 0.005). There were 17 deaths (56.7%) among AKI patients; 4 (28.6%), 1 (25.0%), and 12 (100.0%), respectively. In-hospital mortality was higher in AKI patients than in non-AKI patients (56.7% vs. 20.8%, p < 0.001)...
    Neuropathic pain caused by lesions or nervous system dysfunction is a neuroimmune disease with limited therapeutic options. Adipose tissue-derived stem cells (ASCs) are multipotent mesenchymal stem cells with potent immunosuppressive... more
    Neuropathic pain caused by lesions or nervous system dysfunction is a neuroimmune disease with limited therapeutic options. Adipose tissue-derived stem cells (ASCs) are multipotent mesenchymal stem cells with potent immunosuppressive properties, and their use as novel cell-based therapeutics have been proposed in many immune diseases. However, the analgesic effect and efficacy of ASCs to treat neuropathic pain remain unclear. This study, thus, investigated whether ASCs or ASC-derived culture medium can relieve neuropathic pain behaviors (i.e., mechanical and cold allodynia) in a rat model with L5 spinal nerve ligation. Intrathecal injection of ASCs significantly reduced cold allodynia, but not mechanical allodynia. Importantly, cold allodynia was completely reversed in rats with repeated injections of ASCs. In contrast, intrathecal injection of ASC-derived culture medium or retro-orbital injection of ASCs had no effect on neuropathic pain behaviors. These results suggest a novel and...
    Health inequalities among immigrant minorities have been under-researched in South Korea. This study, therefore, measured the extent of income-related inequalities in self-reported depression and self-rated health (SRH) among married... more
    Health inequalities among immigrant minorities have been under-researched in South Korea. This study, therefore, measured the extent of income-related inequalities in self-reported depression and self-rated health (SRH) among married immigrants in South Korea and decomposed them into sociodemographic determinants using data from the 2015 National Survey of Multicultural Families (n = 15,231). The mean age of this sample was 37.8 years (SD = 10.8) and the mean duration of residence was 10.1 years (SD = 7.4). Eighty-five percent were female, and of these, 86.5% were from low/middle-income countries. Of these married immigrants, 34.6% reported experiences of depressive symptoms in the past year, and 9.5% reported their current health to be poor or very poor (weighted). The results also indicated substantial pro-rich health inequalities with the Erreygers concentration index of −0.1298 for self-reported depression and that of −0.1231 for poor SRH. Socioeconomic positions, reflected in i...
    Data on the relationship between the clinical and microbiological features of community-acquired pneumonia (CAP) and its computed tomography (CT) findings are limited. The aim of the present study was to investigate the... more
    Data on the relationship between the clinical and microbiological features of community-acquired pneumonia (CAP) and its computed tomography (CT) findings are limited. The aim of the present study was to investigate the clinic-microbiological features of patients with CAP presenting with ground-glass opacity (GGO) and centrilobular nodules or tree-in-bud pattern on CT images. Patients with CAP who underwent a CT scan at presentation were retrospectively classified using CT findings into consolidation, GGO and bronchiolitis groups. These 3 groups were compared in terms of clinical parameters and microbiological data. A total of 40 patients (2.4%) were allocated to the bronchiolitis group and 46 (2.8%) to the GGO group. The most common pathogen in the bronchiolitis group was Mycoplasma pneumoniae, which was significantly more frequently isolated in this group. The bronchiolitis group was characterized by a higher percentage of cough, a lower percentage of chest pain and lower blood le...
    Isolation stress is a major risk factor for neuropsychiatric disorders such as depressive and anxiety disorders. However, the molecular mechanisms underlying isolation-induced neuropsychiatric disorders remain elusive. In the present... more
    Isolation stress is a major risk factor for neuropsychiatric disorders such as depressive and anxiety disorders. However, the molecular mechanisms underlying isolation-induced neuropsychiatric disorders remain elusive. In the present study, we investigated the subcellular mechanisms by which long-term isolation elicits depression and anxiety-related behaviors in mice. First, we found that long-term isolation induced depression-related behaviors in the forced swimming test (FST) and the sucrose preference test, as well as anxiety-related behaviors in the elevated zero maze test (EZMT) and the open field test. Next, we showed that intracentral amygdala (CeA) injection of oxytocin (OXT), but not intracerebroventricular injection, attenuated isolation-induced depression and anxiety-related behaviors via oxytocin receptor (OXTR), not vasopressin-1a receptor (V1aR), in the FST and EZMT, respectively. Quantitative real-time polymerase chain reaction analysis revealed that after 5 weeks of ...
    This study was conducted to investigate whether polymorphisms of glucose transporter 1 (GLUT1) gene are associated with the prognosis of patients with non-small cell lung cancer (NSCLC) after surgical resection. Five single nucleotide... more
    This study was conducted to investigate whether polymorphisms of glucose transporter 1 (GLUT1) gene are associated with the prognosis of patients with non-small cell lung cancer (NSCLC) after surgical resection. Five single nucleotide polymorphisms (SNPs) in GLUT1 were investigated in a total of 354 patients with NSCLC who underwent curative surgery. The association of the SNPs with patients' survival was analyzed. Among the five SNPs investigated, two SNPs (GLUT1 rs3820589T > A and rs4658G > C) were significantly associated with OS in multivariate analyses. GLUT1 rs3820589T > A was associated with significantly better OS (adjusted hazard ratio [aHR] = 0.57, 95% confidence interval [CI] = 0.34-0.94, P = 0.03, under dominant model), and rs4658G > C was associated with significantly worse OS (aHR = 1.91, 95% CI = 1.09-3.33, P = 0.02, under recessive model). In the stratified analysis by tumor histology, the effect of these SNPs on OS was only significant in squamous ce...
    Mucinous adenocarcinoma (MAC) is a distinct histologic variant subtype of lung adenocarcinomas. However, detailed radiologic findings and prognostic factors are still poorly understood. Thus, this study aimed to investigate the prognostic... more
    Mucinous adenocarcinoma (MAC) is a distinct histologic variant subtype of lung adenocarcinomas. However, detailed radiologic findings and prognostic factors are still poorly understood. Thus, this study aimed to investigate the prognostic value of quantitative volumetric analysis of the computed tomography images of patients with MAC after. surgical resection. Semiautomatic segmentation from computed tomography images of 60 patients with pathologically confirmed MAC was performed and retrospectively reviewed. The main cutoff value in Hounsfield Units (HU) to predict tumor recurrence was defined by receiver-operating curve analysis. Solid volume of mass (SVM) was defined as the volume of HU greater than this cutoff, and solid ratio (Sratio) was defined as SVM divided by total volume. Each parameter was compared to clinicopathologic characteristics and maximum standardized uptake value. Disease-free survival (DFS) was assessed and was compared among patients. Univariate and multivaria...
    Recent studies have provided several lines of evidence that peripheral administration of oxytocin induces analgesia in human and rodents. However, the exact underlying mechanism of analgesia still remains elusive. In the present study, we... more
    Recent studies have provided several lines of evidence that peripheral administration of oxytocin induces analgesia in human and rodents. However, the exact underlying mechanism of analgesia still remains elusive. In the present study, we aimed to identify which receptor could mediate the analgesic effect of intraperitoneal injection of oxytocin and its cellular mechanisms in thermal pain behavior. We found that oxytocin-induced analgesia could be reversed by d(CH)[Tyr(Me),Dab] AVP, a vasopressin-1a (V1a) receptor antagonist, but not by desGly-NH-d(CH)[DTyr, Thr]OVT, an oxytocin receptor antagonist. Single cell RT-PCR analysis revealed that V1a receptor, compared to oxytocin, vasopressin-1b and vasopressin-2 receptors, was more profoundly expressed in dorsal root ganglion (DRG) neurons and the expression of V1a receptor was predominant in transient receptor potential vanilloid 1 (TRPV1)-expressing DRG neurons. Fura-2 based calcium imaging experiments showed that capsaicin-induced ca...
    Syncope is an unusual clinical manifestation of pulmonary embolism (PE), and the clinical significance of syncope in PE patients remains controversial. We investigated the incidence of syncope, examined the clinical factors associated... more
    Syncope is an unusual clinical manifestation of pulmonary embolism (PE), and the clinical significance of syncope in PE patients remains controversial. We investigated the incidence of syncope, examined the clinical factors associated with syncope, and assessed the association between syncope and the short-term outcomes of PE. We retrospectively classified patients presenting with PE into 2 groups: patients with syncope and those without syncope. We compared the clinical and computed tomography parameters between the groups. Among 1084 patients diagnosed with PE, 45 (4.2%) presented with syncope. Four patients which presented with cardiac arrest were excluded from the study. The syncope group showed significantly higher blood biomarker levels and higher rates of central PE and right ventricular dilation than the control group. Unprovoked PE (odds ratio [OR] 8.046, 95% confidence interval [CI] 3.073-21.069, p < 0.001), female sex (OR 3.419, 95% CI 1.348-8.675, p = 0.010), central ...
    Genome-wide association studies have indicated that most of the currently identified disease and trait-associated single nucleotide polymorphisms (SNPs) are intronic or intergenic. RegulomeDB is a recently developed database that provides... more
    Genome-wide association studies have indicated that most of the currently identified disease and trait-associated single nucleotide polymorphisms (SNPs) are intronic or intergenic. RegulomeDB is a recently developed database that provides functional annotations for regulatory features of SNPs located in non-coding regions. We evaluated the potential regulatory SNPs in the EGFR gene region using RegulomeDB and their associations with prognosis after surgery in non-small cell lung cancer (NSCLC) patients. A total of 698 patients with surgically resected NSCLC were enrolled and seven SNPs were selected based on the RegulomeDB database. All SNPs were genotyped using SEQUENOM MassARRAY iPLEX assay. Among the seven SNPs evaluated, rs9642391 (EGFR ivs19+2851C>G) was significantly associated with survival outcome (adjusted hazard ratio [HR] for overall survival = 0.70, 95% confidence interval [CI] 0.56-0.87, P = 0.001; adjusted HR for disease-free survival = 0.82, 95% CI 0.70-0.97, P = 0...
    Lipoid pneumonia, caused by the accumulation of lipids in the alveoli, is classified into two forms (exogenous endogenous) according to the source of the lipid exposure. There are no data directly comparing patients with exogenous and... more
    Lipoid pneumonia, caused by the accumulation of lipids in the alveoli, is classified into two forms (exogenous endogenous) according to the source of the lipid exposure. There are no data directly comparing patients with exogenous and endogenous lipoid pneumonia. All patients who were diagnosed with lipoid pneumonia between January 2008 and December 2016 at Kyungpook National University Hospital, a tertiary referral hospital in South Korea, were retrospectively reviewed. The clinical, radiologic, and bronchoscopic findings for the two forms of lipoid pneumonia were compared. A total of 13 patients who met the criteria for a confirmed diagnosis of lipoid pneumonia were included. Dyspnea at presentation, predominant lower lobes involvement, bronchial anthracofibrosis (BAF), and recurrent episodes were more frequent in patients with the endogenous form than in those with the exogenous form. Of them, a notable finding was that BAF was identified in all five patients with the endogenous ...
    Patients with lung cancer commonly experience pulmonary embolism (PE). The aim of the present study was to examine the clinical features of patients with lung cancer and PE and to investigate prognostic factors in these patients. This... more
    Patients with lung cancer commonly experience pulmonary embolism (PE). The aim of the present study was to examine the clinical features of patients with lung cancer and PE and to investigate prognostic factors in these patients. This retrospective study divided patients with lung cancer and PE into a group of patients with PE diagnosed concomitantly with lung cancer (concurrent group) and a group with PE detected after lung cancer (sequential group), compared the clinical characteristics of patients in the two groups, and investigated prognostic factors in these patients. The study population consisted of the concurrent group [27 patients (10.1%)] and the sequential group [240 patients (89.9%)]. The concurrent group exhibited higher percentages of stage I cancer at the diagnosis of PE [6 (22.2%) 8 (3.3%), P<0.001] and right ventricular (RV) dilation on computed tomography (CT) [14 (51.9%) 41 (17.1%), P<0.001], as well as lower rate of small cell carcinoma [1 (3.7%) 49 (20.4%)...
    Atopic dermatitis (AD) is a highly pruritic, chronic inflammatory skin disease associated with hyperreactivity to environmental triggers. Among those, outdoor air pollutants such as particulate matter (PM) have been reported to aggravate... more
    Atopic dermatitis (AD) is a highly pruritic, chronic inflammatory skin disease associated with hyperreactivity to environmental triggers. Among those, outdoor air pollutants such as particulate matter (PM) have been reported to aggravate pre-existing AD. However, underlying mechanisms of air pollution-induced aggravation of AD have hardly been studied. To investigate the molecular mechanisms by which glyoxal, a PM-forming organic compound, exacerbates the symptoms of AD induced by neonatal capsaicin treatment. Naïve and AD rats had been exposed to either fresh air or vaporized glyoxal for 5 weeks (2 h/day and 5 days/week) since one week of age. Pruritus and dermatitis were measured every week. The skin and blood were collected and immunological traits such as Staphylococcus aureus skin colonization, production of antimicrobial peptides and immunoglobulin, and mRNA expression of inflammatory cytokines were analyzed. Exposure to glyoxal aggravated pruritus and dermatitis in AD rats, b...
    Laboratory animal models have been developed to investigate preventive or therapeutic effect of medicinal products, or occurrence or progression mechanism of atopic dermatitis (AD), a pruritic and persistent inflammatory skin disease. The... more
    Laboratory animal models have been developed to investigate preventive or therapeutic effect of medicinal products, or occurrence or progression mechanism of atopic dermatitis (AD), a pruritic and persistent inflammatory skin disease. The murine model with immunologic phenomena resembling human AD was introduced, which demonstrated skewedness toward predominance of type-2 helper T cell reactivity and pathophysiological changes similar as human AD following 2,4-dinitrochlorobenzene (DNCB) sensitization and challenge. Molecular mechanism on the DNCB-mediated AD was further evaluated. Skin tissues were collected from mice treated with DNCB, and each tissue was equally divided into two sections; one for protein and the other for mRNA analysis. Expression of filaggrin, an important protein for keratinocyte integrity, was evaluated through SDS-PAGE. Level of mRNA expression for cytokines was determined through semi-quantitative reverse transcriptase polymerase chain reaction. Expression o...
    We conducted this study to identify genetic variants in cancer-related pathway genes which can predict prognosis of NSCLC patients after surgery, using a comprehensive list of regulatory single nucleotide polymorphisms (SNPs) prioritized... more
    We conducted this study to identify genetic variants in cancer-related pathway genes which can predict prognosis of NSCLC patients after surgery, using a comprehensive list of regulatory single nucleotide polymorphisms (SNPs) prioritized by RegulomeDB. A total of 509 potentially functional SNPs in cancer-related pathway genes selected from RegulomeDB were evaluated. These SNPs were analyzed in a discovery set (n=354), and a replication study was performed in an independent set (n=772). The association of the SNPs with overall survival (OS) and disease-free survival (DFS) were analyzed. In the discovery set, 76 SNPs were significantly associated with OS or DFS. Among the 76 SNPs, the association was consistently observed for 5 SNPs (ERCC1 rs2298881C>A, BRCA2 rs3092989G>A, NELFE rs440454C>T, PPP2R4 rs2541164G>A, and LTBP4 rs3786527G>A) in the validation set. In combined analysis, ERCC1 rs2298881C>A, BRCA2 rs3092989, NELFE rs440454C>T, and PPP2R4 rs2541164G>A we...
    A rapidly emerging set of catalytic reactions involves intermediates that contain a copper-substituted stereogenic carbon centre. Here, we demonstrate that an intimate understanding of this distinction provides ways for addressing... more
    A rapidly emerging set of catalytic reactions involves intermediates that contain a copper-substituted stereogenic carbon centre. Here, we demonstrate that an intimate understanding of this distinction provides ways for addressing limitations in reaction scope and explaining why unexpected variations in enantioselectivity often occur. By using catalytic enantioselective Cu-boryl addition to alkenes as the model process, we elucidate several key mechanistic principles. We show that higher electrophile concentration can lead to elevated enantioselectivity. This is because diastereoselective Cu-H elimination may be avoided and/or achiral Cu-boryl intermediates can be converted to allyl-B(pin) rather than add to an alkene. We illustrate that lower alkene amounts and/or higher chiral ligand concentration can minimize the deleterious influence of achiral Cu-alkyl species, resulting in improved enantiomeric ratios. Moreover, and surprisingly, we find that enantioselectivities are higher wi...

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