Antagonistic Effect of Colistin on Vancomycin Activity against Methicillin-Resistant Staphylococcus aureus in In Vitro and In Vivo Studies.

As concerns arise that the vancomycin MIC of methicillin-resistant Staphylococcus aureus (MRSA) could be increased by concurrent colistin administration, we evaluated the effect of colistin on vancomycin efficacy against MRSA via in vitro and in vivo studies. Among MRSA blood isolates collected in a tertiary-care hospital, we selected representative strains from community-associated MRSA strains (CA-MRSA; ST72-MRSA-SCCmec IV) and hospital-acquired MRSA strains (HA-MRSA; ST5-MRSA-SCCmec II). USA CA-MRSA (USA300), HA-MRSA (USA100), N315 (New York/Japan clone), and a MRSA standard strain (ATCC 43300) were used for comparison. We performed checkerboard assays to identify changes in the vancomycin MIC of MRSA following colistin exposure and evaluated the effect of a vancomycin-colistin combination using time-kill assays. We also assessed the in vivo antagonistic effect by administering vancomycin, colistin, and a combination of these two in a neutropenic murine thigh infection model. In the checkerboard assays, vancomycin MICs of all MRSA strains except N315 were increased by from 0.25 to 0.75 µg/ml following colistin exposure. However, the time-kill assays indicated antagonism only against ST5-MRSA and USA100, when the vancomycin concentration was twice the MIC. In the murine thigh infection model with ST5-MRSA and USA100, vancomycin monotherapy reduced the number of CFU/muscle >1 log10 compared to a combination treatment after 24 h in ST5-MRSA, indicating an antagonistic effect of colistin on vancomycin treatment. This study suggests that exposure to colistin may reduce the susceptibility to vancomycin of certain MRSA strains. Combination therapy with vancomycin and colistin for multidrug-resistant pathogens might result in treatment failure for concurrent MRSA infection.

Quadrangular Fixation of Pectus Bars to Prevent Displacement in Nuss Procedure.

BACKGROUND: Double pectus bars are sometimes inserted to correct pectus excavatum. Method of double-bar fixation to prevent bar displacement has been rarely reported. We have used quadrangular fixation of the double pectus bars. The objective of this study was to compare results of the quadrangular fixation procedure with those of the classic separate fixation procedure. METHODS: From September 2011 to January 2016, 86 patients underwent Nuss procedure with double-bar insertion. In 44 patients, each bar was fixed separately (group A). In 42 patients, quadrangular fixation of the bars was performed with metal plates (group B). Patient demographics, Haller index (HI), bar displacement index (BDI), and reoperation rate were compared between the two groups. RESULTS: The mean patient age was 17.2 years (range: 3-40 years) in group A and 17.8 years (range: 4-30 years) in group B. There was no significant difference in preoperative or postoperative HIs between the two groups (all p >0.05). Early complication rates were 15.9% in group A and 9.5% in group B (p > 0.05). In group A, three patients underwent surgery to correct bar displacement (6.8% of reoperation rate), whereas there was no corrective surgery in group B. BDIs of the two groups were significantly different (p < 0.01). CONCLUSIONS: When quadrangular fixation was performed with upper and lower pectus bars bilaterally fixed by connecting each bar with plates, bar displacement was prevented more effectively than separate fixation, thus minimizing reoperation.

Fecal Fatty Acid Profiling as a Potential New Screening Biomarker in Patients with Colorectal Cancer.

BACKGROUND: The fatty acid profile of the fecal metabolome and its association with colorectal cancer (CRC) has not been fully evaluated. AIMS: We aimed to compare the fecal fatty acid profiles of CRC patients and healthy controls. METHODS: We enrolled 26 newly diagnosed CRC patients and 28 healthy individuals between July 2014 and August 2014 from our institute. Long- and short-chain fatty acids were extracted from fecal samples and analyzed using gas chromatography-mass spectrometry. RESULTS: Regarding fecal long-chain fatty acids, the levels of total ω-6 polyunsaturated fatty acids and, particularly, of linoleic acid (C18:2ω-6) were significantly higher in male CRC patients than in healthy men (2.750 ± 2.583 vs. 1.254 ± 0.966 µg/mg feces, P = 0.040; 2.670 ± 2.507 vs. 1.226 ± 0.940 µg/mg feces, P = 0.034, respectively). In addition, the levels of total monounsaturated fatty acid and, particularly, of oleic acid (C18:1ω-9) were significantly higher in male CRC patients than in healthy men (1.802 ± 1.331 vs. 0.977 ± 0.625 µg/mg feces, P = 0.027; 1.749 ± 1.320 vs. 0.932 ± 0.626 µg/mg feces, P = 0.011, respectively). However, those differences were not shown in female gender. The level of fecal short-chain fatty acids was not different between CRC patients and healthy controls. CONCLUSIONS: There were changes in the profiles of fecal fatty acid metabolomes in CRC patients compared to healthy controls, implying that fecal fatty acids could be used as a novel screening tool for CRC.

A Rare Cause of Dyspnea: Cervicothoracic Cystic Lymphangioma.

I read with great interest the article reported by Efe et al in Journal of Cranofacial Surgery (2016;27:1802-1803), presenting the excellent result obtained by the use of sclerotherapy with single-dose OK-432 in a growing cervical lymphangioma. Cervicothoracic lymphangioma is a rare congenital anomaly that is mostly asymptomatic. We would like to share our experience of a rare cause of dyspnea by lymphangioma. In our case, the patient presented with dyspnea and paroxysmal cough caused by cervicothoracic lymphangioma and sclerotherapy alleviated tracheal compression and relieved the dyspneic symptoms.

Emerging Fixation Technique to Prevent Pectus Bar Displacement: Needlescope-Assisted 3-Point Fixation.

BACKGROUND: Bar flipping displacement is one of the most common complications after the Nuss procedure for pectus excavatum. We evaluated the results of a modified Nuss procedure with needlescope-assisted bar fixation. METHODS: The records of 41 patients with pectus excavatum who underwent single pectus bar insertion with the Nuss procedure between July 2011 and August 2014 were retrospectively reviewed. The patients were divided into two groups: those who did not undergo 3-point fixation (group A) and those who did undergo 3-point fixation (group B). RESULTS: There were 36 male patients and 5 female patients with a mean age of 10.7 ± 8.3 years (range: 3-36 years). The postoperative Haller index (HI) (2.61 ± 0.42) was significantly lower than the preoperative HI (3.91 ± 1.07; p < 0.01). The angle of the initial bar position was 5.59 ± 7.37 degrees in group A and 8.52 ± 9.61 degrees in group B, with no significant difference between the groups (p > 0.05). The rate of reoperation to correct bar displacement was lower in group B (3.3%) than in group A (9.1%). CONCLUSION: Needlescope-assisted 3-point fixation of the bar was performed without an additional skin incision and showed a low rate of reoperation to correct displacement of the pectus bar.

Clinical and microbiologic analysis of the risk factors for mortality in patients with heterogeneous vancomycin-intermediate Staphylococcus aureus bacteremia.

The prevalence of the heterogeneous vancomycin-intermediate Staphylococcus aureus (hVISA) phenotype among methicillin-resistant S. aureus (MRSA) blood isolates can reach 38%. hVISA bacteremia is known to be associated with vancomycin treatment failure, including persistent bacteremia. We conducted this study to evaluate risk factors for 12-week mortality in patients with hVISA bacteremia through a detailed clinical and microbiological analysis of a prospective cohort of patients with S. aureus bacteremia. All isolates were collected on the first day of bacteremia and subjected to population analysis profiling for hVISA detection, genotyping, and PCR analysis for 39 virulence factors. Of 382 patient with MRSA bacteremia, 121 (32%) had hVISA bacteremia. Deceased patients were more likely to have hematologic malignancy (P = 0.033), ultimately or rapidly fatal disease (P = 0.007), and a higher Pitt bacteremia score (P = 0.010) than surviving patients. The sequence type 239 (ST239) clonal type and definitive linezolid treatment were associated with a trend toward reduced mortality (P = 0.061 and 0.072, respectively), but a high vancomycin MIC (≥2 mg/liter) was not associated with increased mortality (P = 0.368). In a multivariate analysis, ultimately or rapidly fatal disease (adjusted odds ratio [aOR], 2.80; 95% confidence interval [CI], 1.14 to 6.85) and a high Pitt bacteremia score (aOR, 1.26; 95% CI, 1.07 to 1.48) were independent risk factors for mortality. Hematologic malignancy was associated with a trend toward increased mortality (P = 0.094), and ST239 was associated with a trend toward reduced mortality (P = 0.095). Our study suggests that ST239 hVISA is a possible predictor of survival in hVISA bacteremia.

Community-associated MRSA strain ST72-SCCmecIV causing bloodstream infections: clinical outcomes and bacterial virulence factors.

OBJECTIVES: Community-associated MRSA (CA-MRSA) has emerged in the community and has recently been spreading in healthcare settings. The objectives of this study were to evaluate the clinical outcomes and bacterial virulence factors of the Korean CA-MRSA (ST72-SCCmecIV) strain, which causes bloodstream infections. METHODS: All adult patients with MRSA bacteraemia were prospectively enrolled. Clinical outcomes, microbiological characteristics and 40 bacterial virulence factors were evaluated. RESULTS: Of the 352 typed MRSA isolates, 342 isolates (97.2%) belonged to three Panton-Valentine leucocidin-negative strains: ST5-SCCmecII (70.2%), ST72-SCCmecIV (22.4%) and ST239-SCCmecIII (4.6%). The remaining 10 (2.8%) isolates from minor strains were excluded from the final analysis. After controlling for several confounding factors, ST72-SCCmecIV was associated with the lowest mortality (compared with ST5-SCCmecII, adjusted OR=0.26; 95% CI=0.13-0.54). However, MRSA isolates with vancomycin MICs of ≥ 1.5 mg/L were more common in ST72-SCCmecIV compared with ST5-SCCmecII (84.8% versus 66.7%; P=0.002). Reduced vancomycin susceptibility and vancomycin heteroresistance were not associated with mortality. Compared with ST5-SCCmecII isolates, ST72-SCCmecIV isolates were less likely to harbour multiple virulence genes. Of these genes, three staphylococcal superantigen genes were associated with mortality: sec (OR=2.31; P=0.002), sel (OR=2.55; P=0.003) and tst (OR=2.76; P<0.001). CONCLUSIONS: After controlling for confounding factors, ST72-SCCmecIV was independently associated with lower mortality compared with ST5-SCCmecII, suggesting this CA-MRSA strain to be of lower virulence. The lack of virulence genes, including staphylococcal superantigen genes, may play a role in the lower virulence of this strain.

Prediction of compensatory hyperhidrosis with botulinum toxin A and local anesthetic.

OBJECTIVE: Compensatory hyperhidrosis (CH) is one of the most problematic complications of sympathectomy, which occurs often and is hard to treat. A predictive procedure (PP) for CH can help patients experience compensatory sweating before sympathectomy to determine whether or not to perform sympathectomy. Our study aimed to evaluate the CH after the PP and sympathectomy in patients with primary palmar hyperhidrosis using multiple drugs. METHODS: We reviewed 83 patients who underwent a PP between July 2009 and August 2013 with primary palmar hyperhidrosis. In group A, we used levobupivacaine (n = 39). In group B, we used botulinum toxin A plus ropivacaine for the PP in group B (n = 44). RESULTS: The CH rate after the PP was 44 % (group A) and 25 % (group B), and after sympathectomy 80 % (group A) and 75 % (group B). The prediction value between the PP and the sympathectomy was statistically significant in group A (p < 0.05). The positive prediction rate was 73 % and the negative prediction rate was 27 % in group A. CONCLUSIONS: Local anesthetic alone has a better predictive value. From our finding, patients should be made aware that CH after sympathectomy is less severe in 73 % of cases than that experienced in the PP.

A small Askin's tumor presenting with early onset of chest pain.

Most primitive neuroectodermal tumor of the chest wall destroy the rib, chest wall muscles, diaphragm, and lung or extend into the spinal compartment, resulting in a large-sized tumor and symptoms. In contrast, we recently encountered a rare case of Askin's tumor presenting with early-onset chest pain despite the small size. After resection of the tumor and adjuvant chemotherapy, the patient remains disease-free over 3 years of follow-up.

Predictive procedure for compensatory hyperhidrosis before sympathectomy: preliminary findings.

OBJECTIVE: Compensatory hyperhidrosis is one of the most common and serious adverse effects following sympathectomy. We performed a local anesthetic procedure that predicts the occurrence and severity of compensatory hyperhidrosis, and evaluated the feasibility, safety, and efficacy of the procedure. METHODS AND METHODS: From July 2009 to July 2010, 20 patients with severe primary palmar hyperhidrosis underwent predictive procedures. A sympathetic nerve block was obtained via thoracoscopic approach under local anesthesia. The patients were evaluated for compensatory hyperhidrosis 1 week after the procedure before deciding whether to proceed with sympathectomy. RESULTS: Of the 20 patients, 17 patients proceeded with sympathectomy and 3 refused the final procedure. Following sympathectomy, the occurrence and severity of compensatory hyperhidrosis in the remaining 17 patients were statistically analyzed with two tailed paired t test, and there is no significant difference between the predictive and final procedures (t = 1.69, df = 16, p > 0.1). CONCLUSION: Predictive procedure using local anesthesia to detect compensatory hyperhidrosis before sympathectomy may be useful for helping patients to decide whether to undergo the operation.

Temporal variations in the surface aragonite saturation state of the Yellow Sea: Observations at the Socheongcho Ocean Research Station during 2017-2022.

Accurately constraining the natural variability of the carbonate system is essential for evaluating long-term changes in coastal areas, which result from the absorption of anthropogenic CO2. This is particularly important given the significant variation in physical and biological processes in these regions. In this regard, the analysis of surface carbonate chemistry in the Yellow Sea was conducted using discrete seawater samples obtained from the Socheongcho Ocean Research Station (37.423°N, 124.738°E) between 2017 and 2022. Our bottle data and sensor pH measurements revealed considerable seasonal variations of aragonite saturation state (ΩAR), typically ranging from 1.6 to 3.9. These variations are particularly pronounced during the summer and early winter. Our dataset serves as a baseline for understanding the long-term changes in ocean acidification in the Yellow Sea, the complex biogeochemical processes in coastal areas, and their impact on ocean acidification.

Comparison of inorganic nitrogen concentrations in airborne particles at inshore and offshore sites in the Yellow Sea (2017-2019): Long-range transport and potential impact on marine productivity.

Atmospheric deposition of nitrogen is one of the most important external nutrient sources. We investigated the concentrations of NO3- and NH4+ in airborne particles at both an offshore and an inshore site in the Yellow Sea. At the offshore site, devoid of local sources and located downwind from the highly developed areas of Korea and China, the concentrations of atmospheric particulate NO3- and NH4+ were ∼88 ± 101 nmol m-3 and ∼102 ± 102 nmol m-3, respectively, likely due to the transboundary long-range transport of pollutants. The inshore site showed a concentration ∼2 times higher than the offshore site. Considering not only dry inorganic nitrogen deposition but also wet and organic material deposition, the total atmospheric nitrogen deposition was estimated to contribute roughly 10 % to the new production in the Yellow Sea.

Accessory gene regulator (agr) dysfunction in Staphylococcus aureus bloodstream isolates from South Korean patients.

We describe the genetic and microbiological characteristics of methicillin-resistant Staphylococcus aureus (MRSA) bloodstream isolates with agr dysfunction from a tertiary-care hospital in Korea. Of these, ST5-SCCmec type II-agr group II MRSA isolates, which are known to be prevalent in hospital-acquired infections in Korea, were the most abundant, because of the clonal spread of a specific agr-defective lineage. This finding suggests that the loss of agr function may confer a potential advantage in a hospital setting. Clonal spread of a specific defective-agr strain was not observed among community-associated MRSA or methicillin-susceptible S. aureus clones, regardless of community or hospital acquisition of infection. agr-defective clones, including ST5 and ST239 MRSA, were enriched for heteroresistant vancomycin-intermediate S. aureus.

Treatment duration for uncomplicated Staphylococcus aureus bacteremia to prevent relapse: analysis of a prospective observational cohort study.

Practice guidelines recommend at least 14 days of antibiotic therapy for uncomplicated Staphylococcus aureus bacteremia (SAB). However, these recommendations have not been formally evaluated in clinical studies. To evaluate the duration of therapy for uncomplicated SAB, we analyzed data from our prospective cohort of patients with SAB. A prospective observational cohort study was performed in patients with SAB at a tertiary-care hospital in Korea between August 2008 and September 2010. All adult patients with SAB were prospectively enrolled and observed over a 12-week period. Uncomplicated SAB was defined as follows: negative results of follow-up blood cultures at 2 to 4 days, defervescence within 72 h of therapy, no evidence of metastatic infection, and catheter-related bloodstream infection or primary bacteremia without evidence of endocarditis on echocardiography. Of 483 patients with SAB, 111 met the study criteria for uncomplicated SAB. Fifty-three (47.7%) had methicillin-resistant SAB. When short-course therapy (<14 days) and intermediate-course therapy (≥14 days) were compared, the treatment failure rates (10/38 [26.3%] versus 16/73 [21.9%]) and crude mortality (7/38 [18.4%] versus 16/73 [21.9%]) did not differ significantly between the two groups. However, short-course therapy was significantly associated with relapse (3/38 [7.9%] versus 0/73; P = 0.036). In multivariate analysis, primary bacteremia was associated with a trend toward increased treatment failure (P = 0.06). Therefore, in the treatment of uncomplicated SAB, it seems reasonable to consider at least 14 days of antibiotic therapy to prevent relapse, as practice guidelines recommend. Because of its poor prognosis, primary bacteremia, even with a low risk of complication, should not be treated with short-course therapy.

Point prevalence of Pneumocystis pneumonia in patients with non-Hodgkin lymphoma according to the number of cycles of R-CHOP chemotherapy.

R-CHOP chemotherapy composed of rituximab, cyclophosphamide, adriamycin, vincristine, and prednisolone which might increase the risk of Pneumocystis pneumonia in patients with non-Hodgkin lymphoma. We estimated the point prevalence of Pneumocystis pneumonia in non-Hodgkin lymphoma patients according to the number of R-CHOP cycles and investigated whether cytoreduction by chemotherapy is associated with Pneumocystis pneumonia development. We retrospectively established a cohort of patients who received R-CHOP for non-Hodgkin lymphoma in our institution. Using this cohort, we estimated the incidence rate and point prevalence of definite and probable Pneumocystis pneumonia. To assess factors associated with Pneumocystis pneumonia development several clinical variables, including absolute neutrophil and lymphocyte count at the time of non-Hodgkin lymphoma diagnosis and when the last R-CHOP cycle was administered, were compared between patients with and without Pneumocystis pneumonia. Of 713 patients in the cohort, 14 and 18 patients were diagnosed with definite and probable Pneumocystis pneumonia, respectively. The overall incidence of definite and definite plus probable PCP in NHL patients receiving R-CHOP were 2.0 % (14/713; 95 % CI, 1.1-3.3 %) and 4.5 % (32/713; 95 % CI, 3.2-6.4 %), respectively. This corresponded to 3.8 (95 % CI, 2.2-6.4) and 8.4 (95 % CI, 5.9-11.9) per 1000 persons. Many cases of Pneumocystis pneumonia (22/32, 68.7 %) developed after administration of the fourth R-CHOP cycle. However, there was no statistical difference in Pneumocystis pneumonia prevalence between patients receiving four or more cycles of R-CHOP and fewer than. Higher absolute neutrophil count (4,742/mm(3) vs. 2,627/mm(3); p < 0.01) was associated with Pneumocystis pneumonia development at the last R-CHOP cycle, while absolute lymphocyte count at the time of NHL diagnosis was not. Contrary to expectations, Pneumocystis pneumonia is not a frequent complication of R-CHOP treatment for non-Hodgkin lymphoma. Cytoreduction of R-CHOP might not be a risk factor of Pneumocystis pneumonia development. Universal prophylaxis against Pneumocystis pneumonia during R-CHOP treatment could not be strongly recommended.

Viral infection in patients with severe pneumonia requiring intensive care unit admission.

RATIONALE: The role of viruses in pneumonia in adults and the impact of viral infection on mortality have not been elucidated. Previous studies have significant limitations in that they relied predominantly on upper respiratory specimens. OBJECTIVES: To investigate the role of viral infection in adult patients with pneumonia requiring intensive care unit (ICU) admission. METHODS: A retrospective analysis of a prospective cohort was conducted in a 28-bed medical ICU. Patients with severe community-acquired pneumonia (CAP) or healthcare-associated pneumonia (HCAP) were included in the study. MEASUREMENTS AND MAIN RESULTS: A total of 198 patients (64 with CAP, 134 with HCAP) were included for analysis. Of these, 115 patients (58.1%) underwent bronchoscopic bronchoalveolar lavage (BAL), 104 of whom were tested for respiratory viruses by BAL fluid reverse-transcription polymerase chain reaction (RT-PCR). Nasopharyngeal specimen RT-PCR was performed in 159 patients (84.1%). Seventy-one patients (35.9%) had a bacterial infection, and 72 patients (36.4%) had a viral infection. Rhinovirus was the most common identified virus (23.6%), followed by parainfluenza virus (20.8%), human metapneumovirus (18.1%), influenza virus (16.7%), and respiratory syncytial virus (13.9%). Respiratory syncytial virus was significantly more common in the CAP group (CAP, 10.9%; HCAP, 2.2%; P = 0.01). The mortalities of patients with bacterial infections, viral infections, and bacterial-viral coinfections were not significantly different (25.5, 26.5, and 33.3%, respectively; P = 0.82). CONCLUSIONS: Viruses are frequently found in the airway of patients with pneumonia requiring ICU admission and may cause severe forms of pneumonia. Patients with viral infection and bacterial infection had comparable mortality rates.

Robot-assisted thoracoscopic surgery with simple laparoscopy for diaphragm eventration.

Robot-assisted thoracoscopic surgery has been applied for general thoracic operations. Its advantages include not only those of minimally invasive surgery but also those of magnified three-dimensional vision and angulation of the robotic arm. However, there are no direct tactile sensation and force feedback, which can cause unwanted organ damage. We therefore used laparoscopy simultaneously to avoid a blind intraperitoneal area during robotic surgery for diaphragmatic eventration via transthoracic approach and describe the technique herein.

Non traumatic acquired acute transdiaphragmatic intercostal hernia induced by coughing.

Transdiaphragmatic intercostal hernia is a rare disease. It is usually caused by trauma and is rarely caused by coughing. Although a few cases of intercostal hernia induced by coughing have been reported, our case of a non traumatic acquired acute transdiaphragmatic intercostal and abdominal hernia induced by coughing is very rare. A 77-year-old woman presented with sudden-onset left lower chest pain after an episode of violent coughing. She had risk factors for intercostal hernia, including obesity, chronic obstructive pulmonary disease, oral steroid use, and diabetes mellitus. Computed tomography showed herniation of the lung and intra-abdominal organs into the thoracic and abdominal wall through a ruptured diaphragm, as well as the intercostal and abdominal muscles. Surgery was completed with interrupted sutures to close the defects after the reduction of the herniated organs. Our experience suggests that careful examinations, including the assessment of risk factors and computed tomography imaging, were essential for establishing an accurate diagnosis, and that the repair of a ruptured diaphragm with simple interrupted sutures without any prosthetic materials seems to be feasible in selected patients with a transdiaphragmatic intercostal hernia.

Use of thoracoscopy for thoracic sympathetic nerve block in primary hyperhidrosis.

Thoracic sympathetic nerve block (TSNB) has been widely used in the treatment of neuropathic pain. To reduce block failure rates, TSNB is assisted with several modalities including fluoroscopy, computed tomography, and ultrasonography. The present study describes our experience assessing the usefulness of thoracoscopy in TSNB for predicting compensatory hyperhidrosis before sympathectomy in primary hyperhidrosis. From September 2013 to October 2021, TSNB was performed under local anesthesia using a 2-mm thoracoscope in 302 patients with severe primary hyperhidrosis. Among the 302 patients, 294 were included for analysis. The target level of TSNB was T3 in almost all patients. The mean procedure time was 21 min. Following TSNB, the mean temperature of the left and right palms significantly changed from 31.5 to 35.3 °C and from 31.5 to 34.8 °C, respectively. With TSNB, primary hyperhidrosis was relieved in all patients. Pneumothorax occurred in six patients, in which no chest tube insertion was required. One patient developed hemothorax and was discharged the next day after small-bore catheter drainage. Transient ptosis developed in 10 patients and improved within a day in all patients. Our experiences showed that thoracoscopic TSNB is accurate, safe, and feasible to block the thoracic sympathetic nerve in patients with severe primary hyperhidrosis.

Causes for an extreme cold condition over Northeast Asia during April 2020.

Although 2020 was the fourth warmest year on record in northern Asia, the cold condition in April 2020 caused severe damage to the agricultural and marine ecosystems in northeastern Asia. Previous studies have indicated that the dipole atmospheric circulation over Siberia and the East Sea (Japan Sea) produced this cold environment with strong northwesterly wind. However, the potential causes of the dipole circulation over northeastern Asia remain unclear. In this study, we found that the East Atlantic/Western Russia (EAWR) pattern and blocking combined to produce the atmospheric structure. The wave train originated from the vorticity forcing of northwestern/central Russia and propagated from Western Europe to the East Sea via the background westerly and northerly winds. In addition, the Siberian blocking days increased eleven times in April 2020 relative to the climatological average, and an easterly (westerly) anomaly was observed over Mongolia-northeastern China (northern Russia). The strong blocking and EAWR pattern led to the robust atmospheric dipole structure with a prevailing northerly flow in April 2020, thereby causing the extreme cold condition over northeastern Asia. Our results provide novel insights into the cause of extreme cold condition in April over northeastern Asia.