Ir(tri-N-heterocyclic carbene)-catalyzed upgrading of glycerol: C-C bond formation for the synthesis of α-hydroxy acids.

Ir(triNHC) complexes catalyzed glycerol and alcohol dehydrogenative coupling, yielding diverse α-hydroxy acids. Unlike conventional conditions, Ir(triNHC) facilitated additional C-C bond formation after lactic acid production from glycerol, exhibiting high TOFs. This protocol successfully converted 1,2-propanediol and sorbitol into α-hydroxy acids, highlighting biomass-derived sources' potential as valuable platform chemicals.

Ir(triNHC)-Catalyzed Upcycling of Waste PET for Lactic Acid Production with Sustainable Isolation via Bipolar Membrane Electrodialysis.

For the upcycling of waste polyethylene terephthalate (PET), encompassing both colored and fabric PET materials, we investigated the Ir(triNHC)-catalyzed dehydrogenative coupling of PET and methanol, leading to the production of sodium lactate with good yields. We proposed a sustainable method for isolating lactic acid from the catalytic reaction mixture of sodium lactate and regenerating the base using bipolar membrane electrodialysis (BMED). This isolation method demonstrated high effectiveness, achieving isolation of lactic acid while maintaining economic feasibility at $0.10 per kg of lactic acid, and enabling sustainable NaOH regeneration with complete resource circulation. We assessed the recyclability of the catalyst and elucidated the mechanism involving base-mediated depolymerization and catalyst-promoted dehydrogenation, highlighting the importance of triNHC ligands in enhancing catalytic activity.

Radiologist's Guide to Evaluating Publications of Clinical Research on AI: How We Do It.

Literacy in research studies of artificial intelligence (AI) has become an important skill for radiologists. It is required to make a proper assessment of the validity, reproducibility, and clinical applicability of AI studies. However, AI studies are generally perceived to be more difficult for clinician readers to evaluate than traditional clinical research studies. This special report-as an effective, concise guide for readers-aims to assist clinical radiologists in critically evaluating different types of clinical research articles involving AI. It does not intend to be a comprehensive checklist or methodological summary for complete clinical evaluation of AI or a reporting guideline. Ten key items for readers to check are described, regarding study purpose, function and clinical context of AI, training data, data preprocessing, AI modeling techniques, test data, AI performance, helpfulness and value of AI, interpretability of AI, and code sharing. The important aspects of each item are explained for readers to consider when reading publications on AI clinical research. Evaluating each item can help radiologists assess the validity, reproducibility, and clinical applicability of clinical research articles involving AI.

Methods for Clinical Evaluation of Artificial Intelligence Algorithms for Medical Diagnosis.

Adequate clinical evaluation of artificial intelligence (AI) algorithms before adoption in practice is critical. Clinical evaluation aims to confirm acceptable AI performance through adequate external testing and confirm the benefits of AI-assisted care compared with conventional care through appropriately designed and conducted studies, for which prospective studies are desirable. This article explains some of the fundamental methodological points that should be considered when designing and appraising the clinical evaluation of AI algorithms for medical diagnosis. The specific topics addressed include the following: (a) the importance of external testing of AI algorithms and strategies for conducting the external testing effectively, (b) the various metrics and graphical methods for evaluating the AI performance as well as essential methodological points to note in using and interpreting them, (c) paired study designs primarily for comparative performance evaluation of conventional and AI-assisted diagnoses, (d) parallel study designs primarily for evaluating the effect of AI intervention with an emphasis on randomized clinical trials, and (e) up-to-date guidelines for reporting clinical studies on AI, with an emphasis on guidelines registered in the EQUATOR Network library. Sound methodological knowledge of these topics will aid the design, execution, reporting, and appraisal of clinical evaluation of AI.

Synthesis of α-Hydroxy Acids via Dehydrogenative Cross-Coupling of a Sustainable C2 Chemical (Ethylene Glycol) with Alcohols.

Ir(NHC) (NHC, N-heterocyclic carbene)-catalyzed dehydrogenative coupling of sustainable ethylene glycol and various bioalcohols can produce industrially valuable α-hydroxy acids (AHAs). This study is the first to report the sustainable synthesis of higher Cn AHAs, in addition to glycolic acid (C2 AHA) and lactic acid (C3 AHA). This catalytic system can be recycled to the seventh cycle while maintaining good yields. A reaction mechanism, including facile dehydrogenation of each alcohol and fast cross-coupling of dehydrogenated aldehydes forming products, was proposed based on 18O- and 2H-labeling experiments and electron spray ionization-mass spectrometry (ESI-MS) and NMR spectral analyses.

Factors influencing the stages of frailty among Korean older adults focusing on objective and subjective social isolation.

BACKGROUND: Although many studies have investigated the factors influencing frailty, few studies have confirmed the influence of social factors on the stages of frailty. This study was conducted to identify factors influencing the stages of frailty in Korean older adults, focusing on objective and subjective social isolation. METHODS: This study analyzed the data of 10,041 older adults from the 2017 National Survey of Older Koreans. Two multiple logistic regression analyses were performed to identify the factors influencing the frailty stages. Frailty was calculated using the FRAIL scale with the five domains: fatigue, resistance, ambulation, illness, and loss of weight. RESULTS: Among Korean older adults, 51.5% were in the robust stage, 42.5% in the pre-frail stage and 6.0% in the frail stage. As a multiple logistic regression analysis, participants with an intimate relationship (Odds ratio (OR) 0.93, 95% Confidential interval (CI) = 0.91-0.95) or objective social non-isolated participants were more likely to be in the robust group than the pre-frail group. Objective social-isolated participants were more likely to belong to the frail group than the pre-frail group: isolation from family member only (OR 1.57, 95% CI = 1.04-2.39), isolation from non-family member only (OR 1.75, 95% CI = 1.39-2.19), and isolation from both family and non-family member (OR 2.56, 95% CI = 1.67-3.92). CONCLUSIONS: This cross-sectional study showed that social isolation was associated with the stage of frailty. Therefore, researchers need to consider issues of social isolation of older adults in the development of frailty prevention and management intervention.

The life experiences of living liver donors: A qualitative meta-synthesis.

As living liver transplantation has become a standard treatment method with a high success rate, many studies have investigated the experiences of living liver donors; however, their results have not been integrated. This qualitative meta-synthesis aimed to explore the life experiences of living liver donors to provide an in-depth understanding of meaningful common experiences. A comprehensive search on qualitative studies published in English or Korean was conducted in October 2021. The PRISMA statement was used for reporting each phase of the literature search, and MAXQDA2020 software was used for data analysis. Data synthesis was conducted using the three-step thematic synthesis method suggested by Thomas and Harden. Ten articles met the inclusion criteria. The analysis revealed five main themes: "Becoming an earnest donor," "Transitioning from a potential donor to an actual donor," "Difficulties in returning to normal life," "Re-examining the meaning of donation," and "Wishes for prospective donors." The study emphasizes that living liver donors need medical attention and intervention from multilateral perspectives as well as the need for systematic change in the society to enhance support for donors. This review provides comprehensive insights on how individuals became the living liver donor and the important aspects of living donation and other considerations in an integrated manner. Transplant teams, including nurses and coordinators, should have a comprehensive understanding of physical, psychological, and social experiences of donors ranging from decision-making to post donation health management.

Influence of combined cognitive impairment and social frailty on physical frailty in community-dwelling older adults.

PURPOSE: This study aimed to identify the influence of combined cognitive impairment and social frailty on physical frailty. METHODS: This study analyzed secondary data from the 2020 National Survey of Older Koreans, which was collected nationwide from community-dwelling individuals aged ≥ 65 years. RESULTS: Combined cognitive impairment and social frailty (odds ratio (OR) =4.44, 95% confidence interval (CI)=3.14-6.28), cognitive impairment and social pre-frailty (OR =2.38, 95% CI =1.70-3.34), noncognitive impairment and social frailty (OR =2.16, 95% CI =1.54-3.04), and noncognitive impairment and social pre-frailty (OR =1.40, 95% CI =1.02-1.91) groups were more likely to be physically frail than noncognitive impairment and socially robust groups after adjusting for sociodemographic and health-related factors. CONCLUSION: Healthcare providers need to be aware that older adults who suffer from both cognitive impairment and social frailty may be vulnerable to physical frailty.

Life Experiences of Older Men Living Alone With Depression.

As the percentage of older adults living alone increases, social interest has been drawn to this physically, financially, and socially vulnerable group. The purpose of the current study was to gain a deeper understanding of the life experiences of older men with depression who live alone. Eight community-dwelling men aged ≥65 years who lived alone in Korea and had depression were enrolled in this study. Data were collected via individual in-depth interviews and analyzed using thematic analysis. Four themes emerged from analysis: Life Trapped in the Traditional Masculine Ideology, Weakening Mind and Body, Lost and Helpless, and Beginning of Communication With the World. Results of this study will be helpful in developing more effective depression intervention programs for older men living alone by increasing community health care professionals' understanding and sensitivity. [Journal of Psychosocial Nursing and Mental Health Services, 60(2), 33-40.].

Oxidative cross-coupling of thiols for S-X (X = S, N, O, P, and C) bond formation: mechanistic aspects.

This review focuses on the reactive intermediates (disulfides, sulfenyl halides, thiyl radicals, sulfenium cations, and metal-organosulfur species) and the mechanisms of the recently reported oxidative couplings of thiols. These intermediates are generated by chemical oxidants, transition metal catalysts, electrochemistry, and photochemistry. Chemical oxidant-mediated reactions involve radical, halogenated, or cationic intermediates, or disulfides. Transition metal-catalyzed mechanisms proposed various metal-organosulfur intermediates to elucidate the reactivity and selectivity of metal catalysts. In electro- and photooxidation, direct oxidation/reduction mechanisms of reactants at the electrode or indirect oxidation/reduction of reactants in the presence of redox catalysts have been reported. The following sections are based on the products, thiosulfonates (S-S bond), sulfenamides, sulfinamides, and sulfonamides (S-N bond), sulfinates (S-O bond), thiophosphine oxides and thiophosphates (S-P bond), and sulfides, sulfoxides, and sulfones (S-C bond) and discuss the reaction mechanisms and the above-mentioned key intermediates for product formation. The contents of this review will provide helpful information, guiding the choice of oxidative coupling conditions for the synthesis of various organosulfur compounds with high yields and selectivity.

Critical care nurses' communication challenges during handovers: A systematic review and qualitative meta-synthesis.

AIMS: To review and synthesize qualitative studies to gain a deeper understanding of critical care nurses' inter-departmental and shift-to-shift handover challenges. BACKGROUND: Good-quality nurse-to-nurse handover promotes patient safety, while poor handover has been associated with medical errors. However, systematic reviews of qualitative approaches for better understanding the handover experiences of critical care nurses are lacking. EVALUATION: Systematic review methods incorporating meta-synthesis were used. A comprehensive search of seven databases was conducted. Two independent reviewers performed data extraction and evaluated ten studies using the Critical Appraisal Screening Program. Findings were analysed and synthesized using thematic analysis. The transactional model of communication was used to guide the analysis. KEY ISSUES: A total of 10 qualitative studies were included. Seven major handover themes were identified: (a) expectations of perfection, (b) need for partnership, (c) unilateral communication, (d) obstacles to information acquisition, (e) lack of pertinent patient information, (f) need for a structured handover and (g) interruptions/distractions. CONCLUSIONS: Handovers should be considered an essential part of patient-centred care for ensuring continuity of care. IMPLICATIONS FOR NURSING MANAGEMENT: Poor communication during a handover could increase the nurse's burden or stress and adversely affect patient care. Therefore, training should be provided on explicit handover communication.

Non-enhanced magnetic resonance imaging as a surveillance tool for hepatocellular carcinoma: Comparison with ultrasound.

BACKGROUND & AIMS: Recently revised international guidelines for hepatocellular carcinoma (HCC) suggest that patients with inadequate ultrasonography be assessed by alternative imaging modalities. Non-enhanced MRI has potential as a surveillance tool based on the short scan times required and the absence of contrast agent-associated risks. This study compared the performance of non-enhanced MRI and ultrasonography for HCC surveillance in high-risk patients. METHODS: We included 382 high-risk patients in a prospective cohort who underwent 1 to 3 rounds of paired gadoxetic acid-enhanced MRI and ultrasonography. Non-enhanced MRI, consisting of diffusion-weighted imaging (DWI) and T2-weighted imaging, was simulated and retrospectively analyzed, with results considered positive when lesion(s) ≥1 cm showed diffusion restriction or mild-moderate T2 hyperintensity. Ultrasonography results were retrieved from patient records. HCC was diagnosed histologically and/or radiologically. Sensitivity, positive predictive value (PPV), specificity, and negative predictive value (NPV) were evaluated using generalized estimating equations. RESULTS: Forty-eight HCCs were diagnosed in 43 patients. Per-lesion and per-exam sensitivities of non-enhanced MRI were 77.1% and 79.1%, respectively, which were higher than those achieved with ultrasonography (25.0% and 27.9%, respectively, p <0.001). Specificities of non-enhanced MRI (97.9%) and ultrasonography (94.5%) differed significantly (p <0.001). NPV was higher for non-enhanced MRI (99.1%) than ultrasonography (96.9%). Per-lesion and per-exam PPVs were higher for non-enhanced MRI (56.9% and 61.8%, respectively) than for ultrasonography (16.7% and 17.7%, respectively). The estimated scan time of non-enhanced MRI was <6 min. CONCLUSION: Based on its good performance, short scan times, and the lack of contrast agent-associated risks, non-enhanced MRI is a promising option for HCC surveillance in high-risk patients. LAY SUMMARY: Recently revised international guidelines for hepatocellular carcinoma (HCC) suggest that selected patients with inadequate surveillance on ultrasonography be assessed by alternative imaging modalities such as computed tomography or magnetic resonance imaging (MRI). Herein, we show that MRI without contrast agents performed significantly better than ultrasonography for HCC surveillance in high-risk patients. Given this good performance, as well as short scan times and the lack of contrast agent-associated risks, non-enhanced MRI is a promising option for HCC surveillance in high-risk patients.

Validation of US Liver Imaging Reporting and Data System Version 2017 in Patients at High Risk for Hepatocellular Carcinoma.

Background The 2017 version of the Liver Imaging Reporting and Data System (LI-RADS) recently included standardized interpretation, reporting, and management guidelines for US (US LI-RADS); however, this system has not yet been validated. Purpose To evaluate the diagnostic performance of US LI-RADS version 2017 for detecting hepatocellular carcinoma (HCC) in participants at high risk and to determine the clinical factors associated with a poor visualization score. Materials and Methods This study included 407 prospectively recruited participants (mean age, 56 years; age range, 28-76 years) with cirrhosis at high risk for HCC who underwent US surveillance from November 2011 to August 2012. Two radiologists retrospectively analyzed US images, assigning a LI-RADS category (US-1 = negative, US-2 = subthreshold, US-3 = positive) and a visualization score (A = no or minimal limitations, B = moderate limitations, C = severe limitations). The sensitivity and specificity for diagnosing HCC were calculated on a per-patient and per-lesion basis, using pathologic results and typical CT or MRI as reference standards. The risk factors for a poor visualization score were determined by using univariable and multivariable analyses. Results Of 429 lesions in 407 participants, there were 32 HCCs in 28 participants. In the per-lesion analysis, the specificity for US-3 was 366 of 397 (92%; 95% confidence interval [CI]: 89%, 95%) and the sensitivity was 11 of 32 (34%; 95% CI: 20%, 52%). In the per-patient analysis, the specificity for US-3 was 352 of 379 (93%; 95% CI: 90%, 95%) and the sensitivity was 11 of 28 (39%; 95% CI: 24%, 58%). Visualization score C (114 of 407 [28%] participants) had the highest false-negative rate (six of seven [86%] participants). High body weight (adjusted odds ratio [OR], 2.1 [95% CI: 1.2, 3.6]; P = .01), Child-Pugh class B disease (OR, 2.9 [95% CI: 1.7, 4.9]; P < .001), and moderate to severe fatty liver (OR, 1.7 [95% CI: 1.0, 2.8]; P = .047) were associated with a poor visualization score of C. Conclusion The US-3 category demonstrated high specificity but low sensitivity for diagnosing hepatocellular carcinoma. The visualization score C had a higher false-negative rate than scores A or B, and patients with high body weight, Child-Pugh class B disease, and moderate to severe fatty liver may present limitations for US surveillance. © RSNA, 2019 Online supplemental material is available for this article. See also the editorial by Milot in this issue.

MRI in donor candidates for living donor liver transplant: Technical and practical considerations.

In living donor liver transplantation (LDLT), a thorough preoperative evaluation of the donor is imperative to minimize the risk of the donors and improve the outcome of the recipients. In order to select the best candidate, knowledge of the liver volume, degree of steatosis, and anatomic variations in the vascular and biliary system in potential donors is crucial. With recent technical advances, magnetic resonance imaging (MRI) is increasingly replacing the need for computed tomography (CT) examination in essential steps of donor evaluation. Along with the introduction of higher gradient strength, novel pulse sequences, and innovative contrast media, MRI has a potential to serve as an "all-in-one" imaging package. In this review, we provide an overview of clinical and radiologic considerations related to LDLT and highlight the basics and up-to-date knowledge of MRI techniques for a comprehensive donor evaluation. Level of Evidence: 5 Technical Efficacy: Stage 5 J. Magn. Reson. Imaging 2018;48:1453-1467.

Visibility of the graft hepatic artery using superb microvascular imaging in liver transplantation recipients: initial experience.

Background Hepatic artery (HA) obstruction is one of the most threatening complications following liver transplantation (LT); however, conventional color Doppler imaging (CDI) suffers from technical limitations regarding the visualization of fine vessels and low-velocity blood flow. Purpose To test the visibility of HA in postoperative evaluation of LT using a superb microvascular imaging (SMI). Material and Methods This retrospective study was approved by our institutional review board. Fifty-five consecutive patients (58 grafts; mean age = 56 years) who underwent LT with Doppler ultrasonography (US) on postoperative day 1 were included. We compared the subjective visibility of HA and objective measurements of HA caliber, visible HA length on CDI, monochrome SMI (mSMI), contrast-enhanced mSMI (CE-mSMI), and contrast harmonic imaging (CHI). Reproducibility of HA caliber measurements on SMI techniques were also evaluated by using intraclass correlation coefficients (ICCs). Results The subjective image quality for visibility of HA tended to be graded higher with mSMI than CDI, and with CE-mSMI than mSMI ( P < 0.001). The overall reproducibility of HA caliber measurements was good to excellent for both mSMI and CE-mSMI (ICC = 0.674-0.855). HA caliber measurements on mSMI and CE-mSMI strongly correlated with CHI ( R = 0.785, 0.798, P < 0.001), while mean HA length on mSMI was significantly longer than on CDI (1.88 ± 0.83 vs. 1.42 ± 1.01cm, P = 0.004), and even longer on CE-mSMI (vs. 3.28 ± 1.11 cm, P < 0.001). Conclusion The mSMI technique shows good reproducibility and correlates well with currently used methods for postoperative evaluation of HA in LT recipients. It is further improved by administration of an US contrast agent.

Measurement of liver volumes by portal vein flow by Doppler ultrasound in living donor liver transplantation.

BACKGROUND: The accurate estimation of liver volume and right/left ratio in donor candidates is critical, but there is no method using portal vein (PV) flow. METHODS: Of 125 donor candidates, right/left liver volume ratio was estimated using ultrasound (US)-PV area ratio and Doppler US-PV flow ratio, and the results were compared with CT volumetry. We analyzed these results in 76 donors who underwent hemihepatectomy. We evaluated diagnostic values of Doppler US-PV flow for <30% remnant liver volume high-risk donors, and compared liver volume by Doppler US-PV flow with actual graft weight. RESULTS: In 125 donor candidates, 96.8% showed <10% difference between liver volume ratio by Doppler US-PV flow ratio and CT volumetry. Compared with CT volumetry, the mean percentage difference of liver volume ratio by Doppler US-PV flow ratio was significantly smaller than that by US-PV area ratio (±0.7% vs ±6.3%, P<.001). In 76 donors who underwent hemihepatctomy, results were similar, showing smaller mean percentage difference of liver volume ratio by Doppler US-PV flow ratio than that by US-PV area ratio (±1.0% vs ±6.0%, P<.001). Sensitivity and specificity for <30% remnant liver volume donors were 76.9% and 76.8%. Blood-free liver volume by Doppler US-PV flow was linearly correlated with graft weight (R2 =0.770, P<.001), although significantly different, with 8.5% error ratio (669.3±173.2 vs 633.7±187.1, P=.001). CONCLUSION: Doppler US-PV flow can effectively estimate right/left liver volume ratio in initial donor investigation. However, Doppler US-PV flow is not accurate in assessing donors with <30% remnant liver volume and in estimating actual graft weight.

Synthesis of Sulfones and Sulfonamides via Sulfinate Anions: Revisiting the Utility of Thiosulfonates.

Simple and high-yielding strategies for the production of a variety of sulfones and sulfonamides, using thiosulfonates synthesized by copper-catalyzed aerobic dimerization, are reported. Although thiosulfonates are an old class of compound, practical methods for their synthesis and utilization have not been rigorously developed. In this study, we revisit the reactions of easily accessible thiosulfonates to form sulfinate anions. Because of the similar reactivity of thiosulfonates and metal sulfinates derived from toxic SO2, thiosulfinates are proposed to be stable, nontoxic alternatives to metal sulfinate salts.

MR Enterography Assessment of Bowel Inflammation Severity in Crohn Disease Using the MR Index of Activity Score: Modifying Roles of DWI and Effects of Contrast Phases.

OBJECTIVE: The purpose of this article is to appraise the use of the MR index of activity (MaRIA) score in evaluating Crohn disease (CD) on present-day MR enterography images, with an emphasis on determining the modifying roles of DWI and the effects of different contrast enhancement phases. SUBJECTS AND METHODS: Fifty patients prospectively underwent MR enterography, including DWI and enteric and portal phase scans, and ileocolonoscopy with segmental CD endoscopic index of severity (CDEIS) scoring within a week. Thirty-nine terminal ilea and 40 right-sided colons (mean [± SD] segmental CDEIS score, 14.3 ± 12.1) from 42 patients with CD (mean age, 27 ± 6.2 years) were finally analyzed by three independent readers. Original and modified (ulcer replaced with DWI grade) MaRIA scores were compared regarding their correlation with segmental CDEIS score, accuracy in diagnosing active (segmental CDEIS score ≥ 3) and severe (segmental CDEIS score ≥ 12) inflammation, and interobserver reproducibility. The primary analysis used portal phase data, and the agreement between portal and enteric phase scores was analyzed. RESULTS: MaRIA and modified MaRIA scores correlated similarly with CDEIS scores (r = 0.737 and 0.742; p = 0.387) and did not significantly differ in terms of AUC values for the diagnosis of active (0.909 and 0.903; p = 0.571) or severe (0.907 and 0.892; p = 0.443) inflammation. The intraclass correlation coefficient was significantly higher for modified MaRIA than for MaRIA (0.845 and 0.701; p < 0.001). The mean difference between portal and enteric phase scores (i.e., portal minus enteric) was 0.33-0.36 score points for individual readers, and the Bland-Altman repeatability coefficient was 0.9-1.42 score points. CONCLUSION: Interobserver reproducibility in evaluating the severity of bowel inflammation in CD using the MaRIA score can be improved by modification with DWI. MaRIA scoring provides steady results across enteric and portal phases.

N-butyl-2 cyanoacrylate (NBCA) embolus in the graft portal vein after portosystemic collateral embolization in liver transplantation recipient: what is the clinical significance?

Background An N-butyl-2 cyanoacrylate (NBCA) embolus in the graft portal vein was frequently observed after an intraoperative embolization of portosystemic collaterals performed to prevent portal steal in liver transplant (LT) recipients. The radiological and clinical features of NBCA emboli have not yet been described. Purpose To describe radiological and clinical features of NBCA embolus in graft portal vein after portosystemic collateral embolization in LT recipients. Material and Methods A total of 165 consecutive LT recipients who had undergone intraoperative NBCA embolization of varix were found in single institution's computerized databases of a clinical cohort of LT. Patients were evaluated for NBCA emboli (categorized into major and minor emboli according to location) on first postoperative computed tomography (CT). All electronic medical records and radiologic studies including follow-up was evaluated to determine any radiological and clinical abnormality associated with NBCA embolus. Results NBCA emboli were found in 24% (39/165) of recipients. Although most patients had minor emboli (77%, 30/39) without remarkable ultrasonography (US) abnormalities, seven (78%) of nine recipients with major emboli showed intraluminal echogenic lesions in graft portal vein on grayscale US, and five of them (71%) showed partial portal flow obstruction, although none exhibited any abnormality on contrast-enhanced US. Recipients with NBCA portal emboli showed no significant clinical abnormalities and were discharged safely. NBCA embolus eventually disappeared mostly within six months (82%, 32/39). Conclusion NBCA emboli are frequently observed after portosystemic collateral embolization in LT recipients and are not associated with poor clinical outcome. They may mimic ordinary thromboemboli on US.

Enantioselective synthesis and antioxidant activity of 3,4,5-substituted piperidine derivatives.

In this study, 3,4,5-trisubstituted piperidines were synthesized enantioselectively, and their antioxidant activity was evaluated. The 3,4,5-trisubstituted piperidines containing TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl) and a spatially proximal hydroxy group showed good antioxidant activity. Some of these compounds showed IC50 values in a nanomolar range, comparable to that of TEMPO. Probably the TEMPO generated from the homolysis of the CON bond of 3,4,5-trisubstituted piperidines functions as a radical-scavenging entity, and the hydroxy group of piperidines has a synergistic effect to the antioxidant activity.