Analysis of PM2.5 inorganic and organic constituents to resolve contributing sources in Seoul, South Korea and Beijing, China and their possible associations with cytokine IL-8

China and South Korea are the most polluted countries in East Asia due to significant urbanization and extensive industrial activities. As neighboring countries, collaborative management plans to maximize public health in both countries can be helpful in reducing transboundary air pollution. To support such planning, PM2.5 inorganic and organic species were determined in simultaneously collected PM2.5 integrated filters. The resulting data were used as inputs to positive matrix factorization, which identified nine sources at the ambient air monitoring sites in both sites. Secondary nitrate, secondary sulfate/oil combustion, soil, mobile, incinerator, biomass burning, and secondary organic carbon (SOC) were found to be sources at both sampling sites. Industry I and II were only identified in Seoul, whereas combustion and road dust sources were only identified in Beijing. A subset of samples was selected for exposure assessment. The expression levels of IL-8 were significantly higher in Beijing (167.7 pg/mL) than in Seoul (72.7 pg/mL). The associations between the PM2.5 chemical constituents and its contributing sources with PM2.5-induced inflammatory cytokine (interleukin-8, IL-8) levels in human bronchial epithelial cells were investigated. For Seoul, the soil followed by the secondary nitrate and the biomass burning showed increase with IL-8 production. However, for the Beijing, the secondary nitrate exhibited the highest association with IL-8 production and SOC and biomass burning showed modest increase with IL-8. As one of the highest contributing sources in both cities, secondary nitrate showed an association with IL-8 production. The soil source having the strongest association with IL-8 production was found only for Seoul, whereas SOC showed a modest association only for Beijing. This study can provide the scientific basis for identifying the sources to be prioritized for control to provide effective mitigation of particulate air pollution in each city and thereby improve public health.

Health effects of PM2.5 constituents and source contributions in major metropolitan cities, South Korea

Ambient PM_2.5 is one of the major risk factors for human health, and is not fully explained solely by mass concentration. We examined the short-term associations of cause-specific mortality (i.e., all-cause, cardiovascular, and respiratory mortality) with the 15 chemical constituents and sources of PM_2.5 in four metropolitan cities of South Korea during 2014-2018. We found transition metals consistently showed significant associations with all-cause mortality, while the effects of other constituents varied across the cities and for cause of death. Carbonaceous components strongly affected the all-cause, cardiovascular, and respiratory mortality in Daejeon. Secondary inorganic aerosols, SO₄^2- and NH₄⁺, showed significant associations with respiratory mortality in Gwangju. We also found the sources from which species closely linked to mortality generally increased the relative mortality risks. Heavy metal markers from soil or industrial sources were significantly associated with mortality in all cities. However, several sources influenced mortality despite their marker species not being significantly associated with it. Secondary nitrate and secondary sulfate sources were linked to mortality in DJ. This could be attributed to the deep inland location, which might have facilitated formation of secondary inorganic aerosols. In addition, primary sources including mobile and coal combustion seemed to have acute impacts on respiratory mortality in Gwangju. Our findings suggest the necessity of positive matrix factorization (PMF)-based approaches for evaluating health effects of PM_2.5 while considering the spatial heterogeneity in the compositions and source contributions of PM_2.5.

Genetic and clinical characteristics of transthyretin cardiac amyloidosis in Koreans

Background/Introduction

Transthyretin amyloidosis with mutations (aTTRv amyloidosis) have over 100 recognized pathogenic mutations of the TTR gene and its clinical manifestations are very heterogenous. Through the global THAOS (Transthyretin Amyloidosis Outcomes Survey) patient registry, different and several types of mutants and clinical differences have been identified. Awareness of aTTRv amyloidosis is now becoming somewhat significant amongst physicians all over the world. This is a detailed look at such efforts in Korea.

Purpose

We aimed to seek the geologic significance of aTTRv amyloidosis in South Korea.

Methods

This was an analysis of 638 Korean amyloidosis patients in a single center over a period of 16 years from 1995 to October 2021. 95 individuals were found with aTTR mutations.

Results

aTTRv amyloidosis constituted 14.8% (n=95) of amyloidosis patients, and the most commonly involved organ being the heart (61.7%, n=58). Unlike the rest of the world, the mixed phenotype was most common (51.0%, n=48) in Korea and the most universal mutation in Koreans were Asp38Ala, which only constitutes about 1.0% in the THAOS registry. Val30Met mutation, which comprises 76% of the mutation in the THAOS registry, was mostly associated the neurologic phenotypes. However, the same mutations in Korea mixed phenotypes with cardiac (38.4%) and neurologic (37%) symptoms.

Conclusion

aTTRv amyloidosis in Korea is different from other patients worldwide. The mixed phenotype was most common, emphasizing the need for heart failure management in the Korean population. Genotype wise, Koreans held a less common mutation of Asp38Ala. The most common mutation of Val30Met was more likely to be associated cardiac symptoms, which concurs with other studies that suggesting that geological features are more important than mutations itself.

Funding Acknowledgement

Type of funding sources: None.

Pulmonary arterial angioplasty in peripheral pulmonary arterial stenosis in RNF213 vasculopathy: effective but high-risk treatment with reperfusion injury

Background

p.Arg4810Lys variant of the ring finger protein 213 (RNF213) vasculopathy is a nonsyndromatic vasculopathy involving multisystemic organs including pulmonary arteries. Peripheral pulmonary arterial stenosis (PPAS) with diffuse stenosis and beaded appearance is a unique feature of this disease and no treatment option has been tried before.

Methods

We performed BPA for PPAS in RNF213 patients (n=7). Severity of pulmonary hypertension was assessed by echocardiography and right heart catheterization at the baseline. Several clinical and hemodynamic parameters were followed up after each BPA sessions.

Results

All of the patients had dyspnea on exertion. Right ventricular dysfunction was observed in six patients and NT-proBNP was elevated (949.2±1148.1 pg/mL). Baseline echocardiography showed severe pulmonary hypertension (70.1±19.2 mmHg). Pulmonary arterial ballooning was performed to all patients, but stenting (n=6) and cutting balloon (n=1) was necessary due to elastic recoil. Improvement of clinical and hemodynamic parameters was achieved in six patients after 5.3 sessions of BPA in average. Reperfusion edema was seen in four patients, eventually leading to death in one patient.

Conclusions

Pulmonary arterial angioplasty, when coupled with stenting, is an effective treatment for PPAS with RNF213 vasculopathy. Although reperfusion injury was common and fatal in a few cases, it is the only modality to improve the patient's symptom and hemodynamics till now. Careful selection of the target population should be preceded to perform the intervention.

Funding Acknowledgement

Type of funding sources: None.

α-Fe2O3 nanoparticles and hazardous air pollutants release during cooking using cast iron wok in a commercial Chinese restaurant

Long-term exposure to fine particles (PM_2.5), ultrafine particles (UFPs), and volatile organic compounds (VOCs) emissions from cooking has been linked to adverse human health effects. Here, we measured the real-time number size distribution of particles emitted when cooking two served food in Chinese restaurants and estimated the emission rate of UFPs and PM_2.5. Experiments were conducted under a control hood, and both online measurement and offline analysis of PM_2.5 were carried out. The measured emission rates of PM_2.5 generated from deep-frying and grilling were 0.68 ± 0.11 mg/min and 1.58 ± 0.25 mg/min, respectively. Moreover, the UFPs emission rate of deep-frying (4.3 × 10⁹ #/min) is three times higher than that of grilling (1.4 × 10⁹ #/min). Additionally, the PM_2.5 emission of deep-frying was comprised of a considerable amount of α-Fe₂O₃ (5.7% of PM_2.5 total mass), which is more toxic than other iron oxide species. A total of six carcinogenic HAPs were detected, among which formaldehyde, acrolein, and acetaldehyde were found to exceed the inhalation reference concentration (RfC) for both cooking methods. These findings can contribute to future evaluation of single particle and HAPs emission from cooking to better support toxicity assessment.

Source apportionment of PM2.5 in Seoul, South Korea and Beijing, China using dispersion normalized PMF

East Asian countries experience severe air pollution owing to their rapid development and urbanization induced by substantial economic activities. South Korea and China are among the most polluted East Asian countries with high mass concentrations of PM_2.5. Although the occurrence of transboundary air pollution among neighboring countries has been recognized for a long time, studies involving simultaneous ground-based PM_2.5 monitoring and source apportionment in South Korea and China have not been conducted to date. This study performed simultaneous daily ground-based monitoring of PM_2.5 in Seoul and Beijing from January to December 2019. The mass concentrations of PM_2.5 and its major chemical components were analyzed simultaneously during 2019. Positive matrix factorization (PMF) as well as dispersion normalized PMF (DN-PMF) were utilized for the source apportionment of ambient PM_2.5 at the two sites. 23 h average ventilation coefficients were applied for daily PM_2.5 chemical constituents' data. Nine sources were identified at both sites. While secondary nitrate, secondary sulfate, mobile, oil combustion, biomass burning, soil, and aged sea salt were commonly found at both sites, industry/coal combustion and incinerator were identified only at Seoul and incinerator/industry and coal combustion were identified only at Beijing. Reduction of the meteorological influences were found in DN-PMF compare to C-PMF but the effects of DN on mobile source were reduced by averaging over the 23 h sampling period. The DN-PMF results showed that Secondary nitrate (Seoul: 25.5%; Beijing: 31.7%) and secondary sulfate (Seoul: 20.5%; Beijing: 17.6%) were most dominant contributors to PM_2.5 at both sites. Decreasing secondary sulfate contributions and increasing secondary nitrate contributions were observed at both sites.

Local and transboundary impacts of PM2.5 sources identified in Seoul during the early stage of the COVID-19 outbreak

Countries in Northeast Asia have been regulating PM_2.5 sources and studying their local and transboundary origins since PM_2.5 causes severe impacts on public health and economic losses. However, the separation of local and transboundary impacts is not fully realized because it is impossible to change air pollutant emissions from multiple countries experimentally. Exceptionally, the early stage of the COVID-19 outbreak (January-March 2020) provided a cross-country experiment to separate each impact of PM_2.5 sources identified in Seoul, a downwind area of China. We evaluated the contributions of PM_2.5 sources compared to 2019 using dispersion normalized positive matrix factorization (DN-PMF) during three meteorological episodes. Episodes 1 and 2 revealed transboundary impacts and were related to reduced anthropogenic emissions and accumulated primary pollutants in Northeast China. Anthropogenic emissions, except for the residential sector, decreased, but primary air pollutants accumulated by residential coal combustion enhanced secondary aerosol formation. Thus, the contributions of sulfate and secondary nitrate increased in Seoul during episode 1 but then decreased maximally with other primary sources (biomass burning, district heating and incineration, industrial sources, and oil combustion) during episode 2 under meteorological conditions favorable to long-range transport. Local impact was demonstrated by atmospheric stagnation during episode 3. Meteorological condition unfavorable to local dispersion elevated the contributions of mobile and coal combustion and further contributed to PM_2.5 high concentration events (HCE). Our study separates the local and transboundary impacts and highlights that cooperations in Northeast Asia on secondary aerosol formation and management of local sources are necessary.

Fossil-driven secondary inorganic PM2.5 enhancement in the North China Plain: Evidence from carbon and nitrogen isotopes

Measuring isotopic ratios in aerosol particles is a powerful tool for identifying major sources, particularly in separating fossil from non-fossil sources and investigating aerosol formation processes. We measured the radiocarbon, stable carbon, and stable nitrogen isotopic composition of PM_2.5 in Beijing (BJ) and Changdao (CD) in the North China Plain (NCP) from May to mid-June 2016. The mean PM_2.5 concentrations were 48.6 ± 28.2 μg m^-3 and 71.2 ± 29.0 μg m^-3 in BJ and CD, respectively, with a high contribution (∼66%) from secondary inorganic aerosol (SIA; NO₃^-, NH₄⁺, and SO₄^2-). The mean δ¹³C of total carbon (TC) and δ¹⁵N of total nitrogen (TN) values differed significantly between the two sites (p-value of <0.001): -25.1 ± 0.3‰ in BJ and -24.5 ± 0.4‰ in CD and 10.6 ± 1.8‰ in BJ and 5.0 ± 3.1‰ in CD, respectively. In BJ, the average δ¹⁵N (NH₄⁺) and δ¹⁵N (NO₃^-) values were 12.9 ± 2.3‰ and 5.2 ± 3.5‰, respectively. The ionic molar ratios and isotopic ratios suggest that NO₃^- in BJ was formed through the phase-equilibrium reaction of NH₄NO₃ under sufficient NH_{3 (g)} conditions, promoted by fossil-derived NH_{3 (g)} transported with southerly winds. In BJ, fossil fuel sources comprised 52 ± 7% of TC and 45 ± 28% of NH₄⁺ on average, estimated from radiocarbon (¹⁴C) analysis and the δ¹⁵N and isotope mixing model, respectively. These multiple-isotopic composition results emphasize that PM_2.5 enhancement is derived from fossil sources, in which vehicle emissions are a key contributor. The impact of the coal source was sporadically noticeable. Under regional influences, the fossil fuel-driven SIA led to the PM_2.5 enhancements. Our findings demonstrate that the multiple-isotope approach is highly advantageous to elucidate the key sources and limiting factors of secondary inorganic PM_2.5 aerosols.

Once-daily dosing of amikacin for treatment of Mycobacterium abscessus lung disease

SETTING

Tertiary referral centre, Samsung Medical Center, South Korea.

OBJECTIVE

To evaluate the pharmacokinetic parameters and toxicities of once-daily amikacin (AMK) dosing for lung disease due to Mycobacterium abscessus.

DESIGN

A retrospective review of 48 patients with M. abscessus lung disease who received once-daily AMK for 4 weeks between January 2012 and June 2015.

RESULTS

With a starting dose of 15 mg/kg/day and adjustment of AMK dose according to the peak serum level (Cmax), the Cmax target of 55-65 μg/ml was achieved in 31.3% (15/48) of patients in the first week, 68.8% (33/48) in week 2, 91.7% (44/48) in week 3 and 95.8% (46/48) in week 4. Transient nephrotoxicity developed in 6.3% (3/48) of patients and ototoxicity in 25.0% (6/24), which was determined by audiogram as hearing loss, asymptomatic in five patients and tinnitus in one. Multivariate analysis revealed that the highest drug concentration 12 h after administration was significantly associated with the development of toxicities (adjusted odds ratio 1.862, P = 0.047).

CONCLUSION

Our results suggest that once-daily AMK for 4 weeks with a target Cmax of 55-65 μg/ml can be used in patients with M. abscessus lung disease, with careful monitoring of toxicity.

First Report of the Korean Lung Transplantation Registry

BACKGROUND

The Korean Organ Transplantation Registry (KOTRY) began to register lung transplants in 2015. This is an initial report on the status of patients receiving lung transplants over the past 2 years.

METHODS

We analyzed a total of 69 patients who received lung transplants in 2015 and 2016 and who registered with the KOTRY.

RESULTS

The 69 patients were treated in 5 institutions. The average (SD) donor age was 39.2 (12.6) years; there were 40 male patients. The average (SD) recipient age was 55.7 (10.0) years, and the number of male recipients was 46. A total of 66 patients underwent bilateral lung transplantation, 3 underwent single-lung transplantation, and 1 underwent simultaneous heart-lung transplantation. The most frequent indication for lung transplantation was idiopathic pulmonary fibrosis (35 patients), followed by connective tissue disease-related interstitial lung disease (9) and acute respiratory failure (8). Prior to transplantation, 23 patients required ventilator care, and 12 required extracorporeal membrane oxygenation while on the waiting list. Episodes of acute rejection during follow-up were reported in 4, 2, 1, and 1 patients at 3, 6, 9, and 12 months, respectively. Infections requiring hospitalization were reported in 27, 10, 4, and 3 patients at 3, 6, 9, and 12 months, respectively.

CONCLUSION

The establishment of KOTRY renders it possible to collect nationwide data on lung transplantation, improving research on the topic and clarifying clinical feasibility.

The 100 most-cited articles on non-tuberculous mycobacterial infection from 1995 to 2015

SETTING

Citation analyses aid in assessing quality, trends and future directions of research fields.

OBJECTIVE

To identify the most influential articles on infections caused by non-tuberculous mycobacteria (NTM) in the last 20 years.

DESIGN

We performed a cited reference search of the Web of Science database from 1995 to 2015. The 100 most cited articles on NTM infections were analysed.

RESULTS

The top 100 articles were cited 114-1471 times, and were published from 1995 to 2013. Sixty-five were laboratory-based, basic science articles, with the major topics being pathophysiology (n = 20) and molecular methods for NTM identification (n = 15). Among the 35 non-laboratory studies, major topics were clinical management (n = 15) and epidemiology (n = 14). The top article was a clinical treatise on the management of NTM disease, published in 2007. Although there was a correlation between article rank and journal impact factor (P = 0.043, ρ = -0.202), the five articles from the journals with highest impact factors did not rank among the top 10 articles.

CONCLUSION

A large proportion of influential articles on NTM infection are basic scientific studies, and the most influential articles are not always published in high-impact journals.

Liquid culture enhances diagnosis of patients with milder forms of non-tuberculous mycobacterial lung disease

OBJECTIVE

To evaluate the proportion and clinical characteristics of patients with non-tuberculous mycobacteria (NTM) lung disease diagnosed based on positive culture results in liquid medium only.

METHODS

We reviewed the medical records of 978 patients diagnosed with NTM lung disease. All clinical samples were cultured in both solid and liquid media.

RESULTS

Of the 978 patients, 111 (11.3%) were culture-positive in liquid medium only (liquid culture group), and 867 (88.7%) (solid culture group) on solid medium, regardless of the culture results in liquid medium. At the time of diagnosis, the liquid culture group was less likely than the solid culture group to have haemoptysis (11.7% vs. 20.0%, P = 0.04), positive sputum smear for acid-fast bacilli (14.4% vs. 50.2%, P < 0.001) or the fibrocavitary form of NTM lung disease (3.6% vs. 14.6%, P = 0.001). During the median follow-up period of 28.9 months (interquartile range 19.1-41.6), the proportion of patients requiring antibiotic treatment was lower in the liquid culture group than in the solid culture group (44.1% vs. 61.6%, P < 0.001).

CONCLUSIONS

Liquid media culture is helpful in the diagnosis of patients with less severe forms of NTM lung disease.

Implication of vitamin D-associated factors in patients with non-tuberculous mycobacterial lung disease

BACKGROUND

Little information is available regarding vitamin D-associated factors in patients with non-tuberculous mycobacteria (NTM) lung disease.

OBJECTIVE

To determine the association between vitamin D-related factors and susceptibility to NTM lung disease.

DESIGN

The relative gene expression levels of cathelicidin (CAMP), defensin (DEFB4), vitamin D receptor (VDR) and 1-hydroxylase (CYP27B1), as well as the serum levels of 25-hydroxyvitamin D (25[OH]D), cathelicidin (LL-37), defensin (hBD-2) and vitamin D-binding protein (DBP) from 82 patients with NTM lung disease and 28 control subjects were analysed.

RESULTS

Gene expression of CAMP and DEFB4 was significantly higher, and gene expression of VDR and CYP27B1 was significantly lower, in NTM patients than controls. Serum LL-37 and hBD-2 levels were not significantly different between NTM patients and controls; however, the serum DBP level was higher in NTM patients than controls. The serum vitamin D status of patients did not correlate with serum LL-37, hBD-2, or DBP concentration or gene expression of CAMP, DEFB4, VDR or CYP27B1.

CONCLUSION

A higher level of gene expression for antimicrobial peptide is more likely to be associated with NTM lung disease than serum vitamin D status.

Changes in serum immunomolecules during antibiotic therapy for Mycobacterium avium complex lung disease

Little information is available regarding changes in immune status for patients with Mycobacterium avium complex (MAC) lung disease during antibiotic therapy. Serum immunomolecules from 42 patients with MAC lung disease were assayed comparatively using an array-based system according to (i) patients with MAC lung disease at the time of diagnosis versus healthy controls and (ii) alterations after 12 months of antibiotic therapy in the MAC lung disease group. In addition, cytokine analyses were performed to determine whether cytokine responses were associated specifically with the disease phenotype, treatment outcome and aetiological agent. Notably, the serum concentrations of type 1 cytokine-associated molecules, such as CD40L, interferon (IFN)-γ, interleukin (IL)-8 and IL-23, were decreased significantly in patients at the time of diagnosis, suggesting that these molecules may serve as indicators of host susceptibility to MAC disease. Although the overall serum level of T helper type 1 (Th1)-related molecules, such as CD40L and IFN-γ, was restored after treatment, Th17-related cytokines, such as IL-17 and IL-23, were down-regulated significantly at 12 months post-treatment compared to pretreatment. Furthermore, these cytokine patterns differed among patient subgroups. Decreased serum concentrations of IL-17 and/or IL-23 were associated with failure of sputum conversion, the fibrocavitary disease phenotype and M. intracellulare lung disease. Thus, the reciprocal balance between Th1 and Th17 immunity during antibiotic therapy for MAC lung disease is critical for dictating the treatment response. In conclusion, a low level of Th1-related immunomolecules may perpetuate MAC lung disease, and the serum concentrations of Th17-related cytokines can reflect the treatment outcome, disease phenotype and aetiological agent.

Genotyping of Mycobacterium intracellulare isolates and clinical characteristics of lung disease

BACKGROUND

Variable number of tandem repeats (VNTR) loci were recently identified in Japanese isolates of Mycobacterium intracellulare. We hypothesised that some mycobacterial genotypes are more virulent than others, resulting in particular genotypes being associated with disease phenotype and progression.

OBJECTIVE

To evaluate the VNTR loci of M. intracellulare in clinical isolates from Korean patients, and investigate the association between mycobacterial genotype and disease phenotype and progression.

DESIGN

In total, 70 M. intracellulare clinical isolates were genotyped using 16 M. intracellulare VNTR loci.

RESULTS

VNTR typing showed strong discriminatory power and genetic diversity for molecular epidemiological studies of M. intracellulare. In a phylogenetic tree, the M. intracellulare clinical isolates were divided into two clusters (A and B). Cluster A was observed more frequently (77%) than Cluster B; however, there was no association between the clinical characteristics, disease progression, drug susceptibility and clusters based on VNTR genotyping.

CONCLUSIONS

VNTR typing could be used for epidemiological studies of M. intracellulare lung disease; however, no association was found between the specific VNTR genotypes of M. intracellulare and the clinical characteristics of Korean patients.

Toxocariasis as a cause of new pulmonary infiltrates

SETTING

Patients with new pulmonary infiltrates on chest computed tomography (CT) scans at a tertiary centre in South Korea.

OBJECTIVE

To demonstrate associations among radiological changes, blood eosinophilia (E) and Toxocara (T) seropositivity.

DESIGN

We retrospectively reviewed blood eosinophilia, Toxocara seropositivity, history of raw meat intake and radiological features, and divided study patients into four groups according to blood eosinophilia and Toxocara seropositivity.

RESULTS

Among 150 patients, 62 were E- and T-positive (E+T+), 45 were E-negative and T-positive (E-T+), 7 were E-positive and T-negative (E+T-), and 36 were E- and T-negative (E-T-). History of raw meat intake was found in 95 (63%) patients. The type and number of lesions on CT did not show any significant differences among the four groups. Among 119 patients who were not diagnosed with a specific disease, transient or migrating lesions were seen in 93% of E+T+, 93% of E-T+, 80% of E+T- and 52% of E-T- patients (P < 0.0001). Furthermore, the frequencies of migrating or new lesions and improvement were significantly higher in the Toxocara-positive group (88/95, 93%) than in the Toxocara-negative group (14/24, 58%; P = 0.002).

CONCLUSION

Transient and migratory pulmonary infiltrates on chest CT scans were associated with blood eosinophilia and Toxocara seropositivity. Clinicians should consider asymptomatic toxocariasis as a cause of unexplained new pulmonary infiltrates in countries with dietary habits of raw meat intake.

Clinical significance of mycobacterial genotyping in Mycobacterium avium lung disease in Korea

SETTING

A recent study in Japan found that mycobacterial genotyping was associated with disease progression and susceptibility to certain drugs in Mycobacterium avium lung disease. However, it is not known whether this association is true in other populations.

OBJECTIVE

To investigate the association between mycobacterial genotype, clinical characteristics and the progression of M. avium lung disease in Korean patients.

DESIGN

A total of 102 M. avium clinical isolates were genotyped using M. avium tandem repeats-variable number of tandem repeats (MATR-VNTR).

RESULTS

MATR-VNTR typing demonstrated a high discriminatory power and genetic diversity for molecular epidemiological studies of M. avium. In the phylogenetic tree, the M. avium clinical isolates were divided into three major clusters: A, B and C. Cluster A was observed most frequently (64/102, 63%), whereas cluster C was found in a minor proportion of the isolates (8/102, 8%). However, there was no association between the clinical characteristics, disease progression and drug susceptibility and the phylogenetic tree based on VNTR genotyping.

CONCLUSIONS

MATR-VNTR genotyping may be useful for epidemiological studies of M. avium lung disease; however, no association was found between the specific VNTR genotypes of M. avium and the clinical characteristics of Korean patients.

Paradoxical response in HIV-negative patients with pleural tuberculosis: a retrospective multicentre study

OBJECTIVE

To evaluate the incidence, clinical characteristics and predicting factors for the development of paradoxical response in human immunodeficiency virus negative patients with isolated pleural tuberculosis (TB).

DESIGN

A multicentre, retrospective cohort study including 458 patients who were diagnosed and treated with isolated pleural TB between March 2005 and February 2010.

RESULTS

Paradoxical response developed in 72 patients (16%) with isolated pleural TB. The mean time to development of paradoxical response was 8.8 ± 6.4 weeks after initiation of anti-tuberculosis treatment. The main presentation of paradoxical response was aggravation of pre-existing pleural effusion in 58 patients (81%). However, the majority of the patients who developed paradoxical response had no associated symptoms (n = 49, 68%). In multiple logistic regression analysis, development of paradoxical response was independently associated with the proportion of eosinophils (adjusted OR 1.293, 95%CI 1.077-1.553) and protein concentrations (adjusted OR 0.590, 95%CI 0.397-0.878) in the pleural fluid at the time of diagnosis.

CONCLUSION

Paradoxical response developed in 16% of the patients approximately 2 months after initiation of anti-tuberculosis treatment, presenting with aggravation of pre-existing pleural effusion. Development of paradoxical response was associated with the proportion of eosinophils and protein concentrations in the pleural fluid at the time of diagnosis.

Initial lactate level and mortality in septic shock patients with hepatic dysfunction

An elevated serum lactate level is associated with morbidity and mortality in patients with severe sepsis and septic shock. In patients with hepatic dysfunction, however an elevated serum lactate level may be due to either impaired lactate clearance or excessive production. Thus, we evaluated whether the initial serum lactate level was also associated with mortality in septic shock patients with hepatic dysfunction. A retrospective observational study enrolled 307 patients with septic shock admitted to the intensive care unit (ICU) between May 2007 and July 2009. Hepatic dysfunction was defined as a serum total bilirubin > 34.2 micromol/l (2 mg/dl). Selected patients were divided into high (> or = 4 mmol/l) and low (< 4 mmol/l) lactate groups, according to the initial serum lactate level. Of 307 patients with septic shock, 118 (38%) patients with hepatic dysfunction were eligible for this study. The median lactate levels were 5.9 (interquartile range 4.7 to 9.0) and 2.6 (interquartile range 1.7 to 3.2) mmol/l for the high and low lactate groups respectively (P < 0.001). The initial serum lactate level was strongly associated with in hospital mortality in a univariate analysis (P < 0.001). After adjusting for potential confounding factors, the initial serum lactate level remained significantly associated with in-hospital mortality (odds ratio 1.281, 95% confidence interval 1.097 to 1.496, P = 0.002). In conclusion, the serum lactate level could be useful in predicting the outcome of patients with septic shock regardless of hepatic dysfunction.

Clinical characteristics and outcomes of H1N1-associated pneumonia among adults in South Korea

BACKGROUND

Pneumonia has been reported to be the most life-threatening complication of influenza virus infection.

OBJECTIVE

to describe clinical characteristics and determine risk factors for death among patients with H1N1-associated pneumonia.

DESIGN

A retrospective cohort study included all adult patients diagnosed and treated with H1N1-associated pneumonia in 14 participating institutions between 1 May 2009 and 28 February 2010 in South Korea. Clinical outcomes were summarised and predictors for death evaluated through univariate and multivariate analysis.

RESULTS

A total of 269 adult patients with H1N1-associated pneumonia were diagnosed and treated. Hospital visits or admissions peaked in November 2009, coinciding with the peak in the 2009 H1N1 epidemic in South Korea. The patients' median age was 48 years; 143 were male. Most (n = 266, 98.9%) were admitted for treatment: 97 (36.1%) required intensive care and 28 (10.4%) needed mechanical ventilation. Despite the use of antiviral and antibacterial agents, 19 patients (7.1%) died. Risk factors predictive of death included presence of malignancy (aOR 12.0, 95%CI 2.8-51.5), and pneumonia severity index (PSI) score (aOR 1.03, 95%CI 1.01-1.04).

CONCLUSION

Deaths among adult patients with H1N1-associated pneumonia were not rare. Clinicians should be aware of the possibility of a poor prognosis among H1N1-associated pneumonia patients with underlying malignancy or high PSI score.

High isolation rate of adenovirus serotype 7 from South Korean military recruits with mild acute respiratory disease

Adenovirus is a major cause of acute respiratory disease (ARD) in military recruits. When South Korean military recruits with ARD were surveyed, adenovirus was identified in 122 (61.0%) of the 200 recruits studied. Moreover, all cases of ARD involving adenovirus were caused by serotype 7.

Recovery rate of NTM from AFB smear-positive sputum specimens at a medical centre in South Korea

OBJECTIVE

To investigate the recovery rate of non-tuberculous mycobacteria (NTM) from acid-fast bacilli (AFB) smear-positive sputum specimens at a tertiary care medical centre in South Korea with a high pulmonary tuberculosis (PTB) burden.

DESIGN

Retrospective analysis of data from AFB smear- and culture-positive sputum specimens collected between January 1998 and December 2001.

RESULTS

Over 4 years, 1328 sputum specimens collected from 616 patients were AFB smear- and culture-positive. NTM were recovered from 9.1% (121/1328) of the smear-positive sputum specimens, and from 8.1% (50/616) of patients with smear-positive sputum. NTM were isolated at least twice in 94% (47/50) of the patients from whom NTM was recovered. The most common organism found was Mycobacterium avium complex, followed by M. abscessus.

CONCLUSION

These results suggest that a substantial proportion of patients at a tertiary care medical centre in South Korea with AFB smear-positive sputum specimens may have NTM lung disease rather than PTB.

An efficient real time focusing delay calculation in ultrasonic imaging systems

An efficient real time focusing delay calculation algorithm is proposed for variable sampling clock generation (SCG) with high accuracy needed in digital focusing in ultrasonic imaging systems. The proposed algorithm is an extension of the midpoint drawing algorithm that is well known in the computer graphics area. It can be implemented with simple hardware amenable to VLSI realization, without using a large amount of look-up memory to store the sampling clock information otherwise required.