1.Initial and peak serum levels of Krebs von den Lungen-6 for predicting the prognosis of patients with COVID-19
Geonui KIM ; Hyeonwoo KWON ; Sang Hyun RA ; Euijin CHANG ; Seongman BAE ; Jiwon JUNG ; Min Jae KIM ; Yong Pil CHONG ; Sang-Oh LEE ; Sang-Ho CHOI ; Yang Soo KIM ; Sung-Han KIM
The Korean Journal of Internal Medicine 2025;40(2):321-329
		                        		
		                        			 Background/Aims:
		                        			Krebs von den Lungen-6 (KL-6) is associated with prognosis in patients with COVID-19. However, there is limited data on the correlation between the prognosis of COVID-19 and varying KL-6 levels at different time points. We investigated the optimal cutoff values of the initial and peak serum KL-6 levels to predict mortality and evaluated their correlation with mortality. 
		                        		
		                        			Methods:
		                        			This retrospective cohort study collected data on serially collected serum KL-6 levels in patients hospitalized with COVID-19 between October 2020 and January 2022 at a single tertiary hospital in South Korea. The area under the receiver operating characteristic curve and Youden index were used to determine the cutoff points for the initial and peak KL-6 levels that best predicted 30-day mortality. The association between the initial and peak KL-6 values was assessed by univariate and multivariate logistic regression models. 
		                        		
		                        			Results:
		                        			A total of 349 patients were included in this study. The mean initial and peak KL-6 levels were significantly higher in the non-survivor group than in the survivor group. The initial and peak KL-6 values that best predicted 30-day mortality were 491.85 U/mL and 660.05 U/mL, respectively. An initial KL-6 level greater than 491.85 U/mL and a peak KL-6 level greater than 660.05 U/mL were significantly associated with 30-day mortality. 
		                        		
		                        			Conclusions
		                        			The initial and peak levels of KL-6 were significantly associated with 30-day mortality in hospitalized patients with COVID-19. These findings suggest that serially monitoring blood KL-6 levels could be a valuable prognostic indicator for COVID-19. 
		                        		
		                        		
		                        		
		                        	
2.Intelligent handheld ultrasound improving the ability of non-expert general practitioners in carotid examinations for community populations: a prospective and parallel controlled trial
Pei SUN ; Hong HAN ; Yi-Kang SUN ; Xi WANG ; Xiao-Chuan LIU ; Bo-Yang ZHOU ; Li-Fan WANG ; Ya-Qin ZHANG ; Zhi-Gang PAN ; Bei-Jian HUANG ; Hui-Xiong XU ; Chong-Ke ZHAO
Ultrasonography 2025;44(2):112-123
		                        		
		                        			 Purpose:
		                        			The aim of this study was to investigate the feasibility of an intelligent handheld ultrasound (US) device for assisting non-expert general practitioners (GPs) in detecting carotid plaques (CPs) in community populations. 
		                        		
		                        			Methods:
		                        			This prospective parallel controlled trial recruited 111 consecutive community residents. All of them underwent examinations by non-expert GPs and specialist doctors using handheld US devices (setting A, setting B, and setting C). The results of setting C with specialist doctors were considered the gold standard. Carotid intima-media thickness (CIMT) and the features of CPs were measured and recorded. The diagnostic performance of GPs in distinguishing CPs was evaluated using a receiver operating characteristic curve. Inter-observer agreement was compared using the intragroup correlation coefficient (ICC). Questionnaires were completed to evaluate clinical benefits. 
		                        		
		                        			Results:
		                        			Among the 111 community residents, 80, 96, and 112 CPs were detected in settings A, B, and C, respectively. Setting B exhibited better diagnostic performance than setting A for detecting CPs (area under the curve, 0.856 vs. 0.749; P<0.01). Setting B had better consistency with setting C than setting A in CIMT measurement and the assessment of CPs (ICC, 0.731 to 0.923). Moreover, measurements in setting B required less time than the other two settings (44.59 seconds vs. 108.87 seconds vs. 126.13 seconds, both P<0.01). 
		                        		
		                        			Conclusion
		                        			Using an intelligent handheld US device, GPs can perform CP screening and achieve a diagnostic capability comparable to that of specialist doctors. 
		                        		
		                        		
		                        		
		                        	
3.Minocycline Susceptibility of Carbapenem-Resistant Acinetobacter baumannii Blood Isolates from a Single Center in Korea: Role of tetB in Resistance
Taeeun KIM ; Eun Hee JEON ; Yoon-Kyoung HONG ; Jiwon JUNG ; Min Jae KIM ; Heungsup SUNG ; Mi-Na KIM ; Sung-Han KIM ; Sang-Ho CHOI ; Sang-Oh LEE ; Yang Soo KIM ; Yong Pil CHONG
Infection and Chemotherapy 2025;57(1):111-118
		                        		
		                        			 Background:
		                        			Carbapenem-resistant Acinetobacter baumannii (CRAB) represents a devastating and growing global threat, calling for new antibiotic treatments. In Korea, the challenge of treating CRAB is compounded by high nosocomial acquisition rates and limited availability of novel antibiotics. Minocycline, a semisynthetic tetracycline derivative, has been proposed as a therapeutic option for CRAB infections. Nonsusceptibility to minocycline may occur through the efflux pump, TetB. The prevalence of tetB in A. baumannii has increased, along with higher minocycline minimum inhibitory concentrations (MICs). We aimed to evaluate minocycline susceptibility rates in clinical strains of CRAB, and the association between tetB carriage and minocycline susceptibility across different genotypes. 
		                        		
		                        			Materials and Methods:
		                        			Representative CRAB blood isolates were collected from Asan Medical Center, Seoul.Minocycline susceptibility was assessed using the Clinical and Laboratory Standards Institute (CLSI) breakpoint (≤4 mg/L) and the proposed pharmacokinetics (PK)/pharmacodynamics (PD) breakpoint (≤1 mg/L). Tigecycline was used as a comparator, and its susceptibility breakpoint for Enterobacterales defined by EUCAST was applied (≤0.5 mg/L).The presence of tetB was detected by PCR, and multilocus sequence typing (MLST) was performed using seven housekeeping genes. 
		                        		
		                        			Results:
		                        			Of the 160 CRAB blood isolates, 83.8% were susceptible to minocycline by the CLSI criteria, and 50.6% were PK-PD susceptible by the PK-PD criteria. The minocycline minimum inhibitory concentration (MIC)50 /MIC90 was 1/8 mg/L. tetB was present in 49% of isolates and was associated with a higher minocycline MIC (MIC50/90 2/8 mg/L vs. 1/2 mg/L). No clear correlation was observed between tetB positivity and tigecycline MIC. Nine MLSTs were identified, with significant differences in tetB carriage rates between the major sequence types. Notably, ST191, associated with non-tetB carriage and greater susceptibility to minocycline, declined over the study period (P=0.004), while ST451, associated with tetB carriage, increased. 
		                        		
		                        			Conclusion
		                        			tetB was present in 49% of CRAB isolates and was associated with higher MICs and non-susceptibility by both CLSI and PK-PD criteria. However, absence of tetB was not a reliable predictor of minocycline PK-PD susceptibility. Additionally, shifts over time towards genotypes with reduced minocycline susceptibility were observed. Further research is needed to correlate these findings with clinical outcomes and identify additional resistance mechanisms. 
		                        		
		                        		
		                        		
		                        	
4.Initial and peak serum levels of Krebs von den Lungen-6 for predicting the prognosis of patients with COVID-19
Geonui KIM ; Hyeonwoo KWON ; Sang Hyun RA ; Euijin CHANG ; Seongman BAE ; Jiwon JUNG ; Min Jae KIM ; Yong Pil CHONG ; Sang-Oh LEE ; Sang-Ho CHOI ; Yang Soo KIM ; Sung-Han KIM
The Korean Journal of Internal Medicine 2025;40(2):321-329
		                        		
		                        			 Background/Aims:
		                        			Krebs von den Lungen-6 (KL-6) is associated with prognosis in patients with COVID-19. However, there is limited data on the correlation between the prognosis of COVID-19 and varying KL-6 levels at different time points. We investigated the optimal cutoff values of the initial and peak serum KL-6 levels to predict mortality and evaluated their correlation with mortality. 
		                        		
		                        			Methods:
		                        			This retrospective cohort study collected data on serially collected serum KL-6 levels in patients hospitalized with COVID-19 between October 2020 and January 2022 at a single tertiary hospital in South Korea. The area under the receiver operating characteristic curve and Youden index were used to determine the cutoff points for the initial and peak KL-6 levels that best predicted 30-day mortality. The association between the initial and peak KL-6 values was assessed by univariate and multivariate logistic regression models. 
		                        		
		                        			Results:
		                        			A total of 349 patients were included in this study. The mean initial and peak KL-6 levels were significantly higher in the non-survivor group than in the survivor group. The initial and peak KL-6 values that best predicted 30-day mortality were 491.85 U/mL and 660.05 U/mL, respectively. An initial KL-6 level greater than 491.85 U/mL and a peak KL-6 level greater than 660.05 U/mL were significantly associated with 30-day mortality. 
		                        		
		                        			Conclusions
		                        			The initial and peak levels of KL-6 were significantly associated with 30-day mortality in hospitalized patients with COVID-19. These findings suggest that serially monitoring blood KL-6 levels could be a valuable prognostic indicator for COVID-19. 
		                        		
		                        		
		                        		
		                        	
5.Intelligent handheld ultrasound improving the ability of non-expert general practitioners in carotid examinations for community populations: a prospective and parallel controlled trial
Pei SUN ; Hong HAN ; Yi-Kang SUN ; Xi WANG ; Xiao-Chuan LIU ; Bo-Yang ZHOU ; Li-Fan WANG ; Ya-Qin ZHANG ; Zhi-Gang PAN ; Bei-Jian HUANG ; Hui-Xiong XU ; Chong-Ke ZHAO
Ultrasonography 2025;44(2):112-123
		                        		
		                        			 Purpose:
		                        			The aim of this study was to investigate the feasibility of an intelligent handheld ultrasound (US) device for assisting non-expert general practitioners (GPs) in detecting carotid plaques (CPs) in community populations. 
		                        		
		                        			Methods:
		                        			This prospective parallel controlled trial recruited 111 consecutive community residents. All of them underwent examinations by non-expert GPs and specialist doctors using handheld US devices (setting A, setting B, and setting C). The results of setting C with specialist doctors were considered the gold standard. Carotid intima-media thickness (CIMT) and the features of CPs were measured and recorded. The diagnostic performance of GPs in distinguishing CPs was evaluated using a receiver operating characteristic curve. Inter-observer agreement was compared using the intragroup correlation coefficient (ICC). Questionnaires were completed to evaluate clinical benefits. 
		                        		
		                        			Results:
		                        			Among the 111 community residents, 80, 96, and 112 CPs were detected in settings A, B, and C, respectively. Setting B exhibited better diagnostic performance than setting A for detecting CPs (area under the curve, 0.856 vs. 0.749; P<0.01). Setting B had better consistency with setting C than setting A in CIMT measurement and the assessment of CPs (ICC, 0.731 to 0.923). Moreover, measurements in setting B required less time than the other two settings (44.59 seconds vs. 108.87 seconds vs. 126.13 seconds, both P<0.01). 
		                        		
		                        			Conclusion
		                        			Using an intelligent handheld US device, GPs can perform CP screening and achieve a diagnostic capability comparable to that of specialist doctors. 
		                        		
		                        		
		                        		
		                        	
6.Initial and peak serum levels of Krebs von den Lungen-6 for predicting the prognosis of patients with COVID-19
Geonui KIM ; Hyeonwoo KWON ; Sang Hyun RA ; Euijin CHANG ; Seongman BAE ; Jiwon JUNG ; Min Jae KIM ; Yong Pil CHONG ; Sang-Oh LEE ; Sang-Ho CHOI ; Yang Soo KIM ; Sung-Han KIM
The Korean Journal of Internal Medicine 2025;40(2):321-329
		                        		
		                        			 Background/Aims:
		                        			Krebs von den Lungen-6 (KL-6) is associated with prognosis in patients with COVID-19. However, there is limited data on the correlation between the prognosis of COVID-19 and varying KL-6 levels at different time points. We investigated the optimal cutoff values of the initial and peak serum KL-6 levels to predict mortality and evaluated their correlation with mortality. 
		                        		
		                        			Methods:
		                        			This retrospective cohort study collected data on serially collected serum KL-6 levels in patients hospitalized with COVID-19 between October 2020 and January 2022 at a single tertiary hospital in South Korea. The area under the receiver operating characteristic curve and Youden index were used to determine the cutoff points for the initial and peak KL-6 levels that best predicted 30-day mortality. The association between the initial and peak KL-6 values was assessed by univariate and multivariate logistic regression models. 
		                        		
		                        			Results:
		                        			A total of 349 patients were included in this study. The mean initial and peak KL-6 levels were significantly higher in the non-survivor group than in the survivor group. The initial and peak KL-6 values that best predicted 30-day mortality were 491.85 U/mL and 660.05 U/mL, respectively. An initial KL-6 level greater than 491.85 U/mL and a peak KL-6 level greater than 660.05 U/mL were significantly associated with 30-day mortality. 
		                        		
		                        			Conclusions
		                        			The initial and peak levels of KL-6 were significantly associated with 30-day mortality in hospitalized patients with COVID-19. These findings suggest that serially monitoring blood KL-6 levels could be a valuable prognostic indicator for COVID-19. 
		                        		
		                        		
		                        		
		                        	
7.Intelligent handheld ultrasound improving the ability of non-expert general practitioners in carotid examinations for community populations: a prospective and parallel controlled trial
Pei SUN ; Hong HAN ; Yi-Kang SUN ; Xi WANG ; Xiao-Chuan LIU ; Bo-Yang ZHOU ; Li-Fan WANG ; Ya-Qin ZHANG ; Zhi-Gang PAN ; Bei-Jian HUANG ; Hui-Xiong XU ; Chong-Ke ZHAO
Ultrasonography 2025;44(2):112-123
		                        		
		                        			 Purpose:
		                        			The aim of this study was to investigate the feasibility of an intelligent handheld ultrasound (US) device for assisting non-expert general practitioners (GPs) in detecting carotid plaques (CPs) in community populations. 
		                        		
		                        			Methods:
		                        			This prospective parallel controlled trial recruited 111 consecutive community residents. All of them underwent examinations by non-expert GPs and specialist doctors using handheld US devices (setting A, setting B, and setting C). The results of setting C with specialist doctors were considered the gold standard. Carotid intima-media thickness (CIMT) and the features of CPs were measured and recorded. The diagnostic performance of GPs in distinguishing CPs was evaluated using a receiver operating characteristic curve. Inter-observer agreement was compared using the intragroup correlation coefficient (ICC). Questionnaires were completed to evaluate clinical benefits. 
		                        		
		                        			Results:
		                        			Among the 111 community residents, 80, 96, and 112 CPs were detected in settings A, B, and C, respectively. Setting B exhibited better diagnostic performance than setting A for detecting CPs (area under the curve, 0.856 vs. 0.749; P<0.01). Setting B had better consistency with setting C than setting A in CIMT measurement and the assessment of CPs (ICC, 0.731 to 0.923). Moreover, measurements in setting B required less time than the other two settings (44.59 seconds vs. 108.87 seconds vs. 126.13 seconds, both P<0.01). 
		                        		
		                        			Conclusion
		                        			Using an intelligent handheld US device, GPs can perform CP screening and achieve a diagnostic capability comparable to that of specialist doctors. 
		                        		
		                        		
		                        		
		                        	
8.Minocycline Susceptibility of Carbapenem-Resistant Acinetobacter baumannii Blood Isolates from a Single Center in Korea: Role of tetB in Resistance
Taeeun KIM ; Eun Hee JEON ; Yoon-Kyoung HONG ; Jiwon JUNG ; Min Jae KIM ; Heungsup SUNG ; Mi-Na KIM ; Sung-Han KIM ; Sang-Ho CHOI ; Sang-Oh LEE ; Yang Soo KIM ; Yong Pil CHONG
Infection and Chemotherapy 2025;57(1):111-118
		                        		
		                        			 Background:
		                        			Carbapenem-resistant Acinetobacter baumannii (CRAB) represents a devastating and growing global threat, calling for new antibiotic treatments. In Korea, the challenge of treating CRAB is compounded by high nosocomial acquisition rates and limited availability of novel antibiotics. Minocycline, a semisynthetic tetracycline derivative, has been proposed as a therapeutic option for CRAB infections. Nonsusceptibility to minocycline may occur through the efflux pump, TetB. The prevalence of tetB in A. baumannii has increased, along with higher minocycline minimum inhibitory concentrations (MICs). We aimed to evaluate minocycline susceptibility rates in clinical strains of CRAB, and the association between tetB carriage and minocycline susceptibility across different genotypes. 
		                        		
		                        			Materials and Methods:
		                        			Representative CRAB blood isolates were collected from Asan Medical Center, Seoul.Minocycline susceptibility was assessed using the Clinical and Laboratory Standards Institute (CLSI) breakpoint (≤4 mg/L) and the proposed pharmacokinetics (PK)/pharmacodynamics (PD) breakpoint (≤1 mg/L). Tigecycline was used as a comparator, and its susceptibility breakpoint for Enterobacterales defined by EUCAST was applied (≤0.5 mg/L).The presence of tetB was detected by PCR, and multilocus sequence typing (MLST) was performed using seven housekeeping genes. 
		                        		
		                        			Results:
		                        			Of the 160 CRAB blood isolates, 83.8% were susceptible to minocycline by the CLSI criteria, and 50.6% were PK-PD susceptible by the PK-PD criteria. The minocycline minimum inhibitory concentration (MIC)50 /MIC90 was 1/8 mg/L. tetB was present in 49% of isolates and was associated with a higher minocycline MIC (MIC50/90 2/8 mg/L vs. 1/2 mg/L). No clear correlation was observed between tetB positivity and tigecycline MIC. Nine MLSTs were identified, with significant differences in tetB carriage rates between the major sequence types. Notably, ST191, associated with non-tetB carriage and greater susceptibility to minocycline, declined over the study period (P=0.004), while ST451, associated with tetB carriage, increased. 
		                        		
		                        			Conclusion
		                        			tetB was present in 49% of CRAB isolates and was associated with higher MICs and non-susceptibility by both CLSI and PK-PD criteria. However, absence of tetB was not a reliable predictor of minocycline PK-PD susceptibility. Additionally, shifts over time towards genotypes with reduced minocycline susceptibility were observed. Further research is needed to correlate these findings with clinical outcomes and identify additional resistance mechanisms. 
		                        		
		                        		
		                        		
		                        	
9.Initial and peak serum levels of Krebs von den Lungen-6 for predicting the prognosis of patients with COVID-19
Geonui KIM ; Hyeonwoo KWON ; Sang Hyun RA ; Euijin CHANG ; Seongman BAE ; Jiwon JUNG ; Min Jae KIM ; Yong Pil CHONG ; Sang-Oh LEE ; Sang-Ho CHOI ; Yang Soo KIM ; Sung-Han KIM
The Korean Journal of Internal Medicine 2025;40(2):321-329
		                        		
		                        			 Background/Aims:
		                        			Krebs von den Lungen-6 (KL-6) is associated with prognosis in patients with COVID-19. However, there is limited data on the correlation between the prognosis of COVID-19 and varying KL-6 levels at different time points. We investigated the optimal cutoff values of the initial and peak serum KL-6 levels to predict mortality and evaluated their correlation with mortality. 
		                        		
		                        			Methods:
		                        			This retrospective cohort study collected data on serially collected serum KL-6 levels in patients hospitalized with COVID-19 between October 2020 and January 2022 at a single tertiary hospital in South Korea. The area under the receiver operating characteristic curve and Youden index were used to determine the cutoff points for the initial and peak KL-6 levels that best predicted 30-day mortality. The association between the initial and peak KL-6 values was assessed by univariate and multivariate logistic regression models. 
		                        		
		                        			Results:
		                        			A total of 349 patients were included in this study. The mean initial and peak KL-6 levels were significantly higher in the non-survivor group than in the survivor group. The initial and peak KL-6 values that best predicted 30-day mortality were 491.85 U/mL and 660.05 U/mL, respectively. An initial KL-6 level greater than 491.85 U/mL and a peak KL-6 level greater than 660.05 U/mL were significantly associated with 30-day mortality. 
		                        		
		                        			Conclusions
		                        			The initial and peak levels of KL-6 were significantly associated with 30-day mortality in hospitalized patients with COVID-19. These findings suggest that serially monitoring blood KL-6 levels could be a valuable prognostic indicator for COVID-19. 
		                        		
		                        		
		                        		
		                        	
10.Intelligent handheld ultrasound improving the ability of non-expert general practitioners in carotid examinations for community populations: a prospective and parallel controlled trial
Pei SUN ; Hong HAN ; Yi-Kang SUN ; Xi WANG ; Xiao-Chuan LIU ; Bo-Yang ZHOU ; Li-Fan WANG ; Ya-Qin ZHANG ; Zhi-Gang PAN ; Bei-Jian HUANG ; Hui-Xiong XU ; Chong-Ke ZHAO
Ultrasonography 2025;44(2):112-123
		                        		
		                        			 Purpose:
		                        			The aim of this study was to investigate the feasibility of an intelligent handheld ultrasound (US) device for assisting non-expert general practitioners (GPs) in detecting carotid plaques (CPs) in community populations. 
		                        		
		                        			Methods:
		                        			This prospective parallel controlled trial recruited 111 consecutive community residents. All of them underwent examinations by non-expert GPs and specialist doctors using handheld US devices (setting A, setting B, and setting C). The results of setting C with specialist doctors were considered the gold standard. Carotid intima-media thickness (CIMT) and the features of CPs were measured and recorded. The diagnostic performance of GPs in distinguishing CPs was evaluated using a receiver operating characteristic curve. Inter-observer agreement was compared using the intragroup correlation coefficient (ICC). Questionnaires were completed to evaluate clinical benefits. 
		                        		
		                        			Results:
		                        			Among the 111 community residents, 80, 96, and 112 CPs were detected in settings A, B, and C, respectively. Setting B exhibited better diagnostic performance than setting A for detecting CPs (area under the curve, 0.856 vs. 0.749; P<0.01). Setting B had better consistency with setting C than setting A in CIMT measurement and the assessment of CPs (ICC, 0.731 to 0.923). Moreover, measurements in setting B required less time than the other two settings (44.59 seconds vs. 108.87 seconds vs. 126.13 seconds, both P<0.01). 
		                        		
		                        			Conclusion
		                        			Using an intelligent handheld US device, GPs can perform CP screening and achieve a diagnostic capability comparable to that of specialist doctors. 
		                        		
		                        		
		                        		
		                        	
            
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