The difference of detection rate of avian influenza virus in the wild bird surveillance using various methods

Korea is located within the East Asian-Australian flyway of wild migratory birds during the fall and winter seasons. Consequently, the likelihood of introduction of numerous subtypes and pathotypes of the Avian influenza (AI) virus to Korea has been thought to be very high. In the current study, we surveyed wild bird feces for the presence of AI virus that had been introduced to Korea between September 2017 and February 2018. To identify and characterize the AI virus, we employed commonly used methods, namely, virus isolation (VI) via egg inoculation, real-time reverse transcription-polymerase chain reaction (rRT-PCR), conventional RT-PCR (cRT-PCR) and a newly developed next generation sequencing (NGS) approach. In this study, 124 out of 11,145 fresh samples of wild migratory birds tested were rRT-PCR positive; only 52.0% of VI positive samples were determined as positive by rRT-PCR from fecal supernatant. Fifty AI virus specimens were isolated from fresh fecal samples and typed. The cRT-PCR subtyping results mostly coincided with the NGS results, although NGS detected the presence of 11 HA genes and four NA genes that were not detected by cRT-PCR. NGS analysis confirmed that 12% of the identified viruses were mixed-subtypes which were not detected by cRT-PCR. Prevention of the occurrence of AI virus requires a workflow for rapid and accurate virus detection and verification. However, conventional methods of detection have some limitations. Therefore, different methods should be combined for optimal surveillance, and further studies are needed in aspect of the introduction and application of new methods such as NGS.

Molecular characterization of highly pathogenic avian influenza H5N8 viruses isolated from Baikal teals found dead during a 2014 outbreak in Korea

Nineteen highly pathogenic avian influenza (HPAI) H5N8 viruses were isolated from wild birds in the Donglim reservoir in Gochang, Jeonbuk province, Korea, which was first reported to be an outbreak site on January 17, 2014. Most genes from the nineteen viruses shared high nucleotide sequence identities (i.e., 99.7% to 100%). Phylogenetic analysis showed that these viruses were reassortants of the HPAI H5 subtype and the H4N2 strain and that their hemagglutinin clade was 2.3.4.4, which originated from Eastern China. The hemagglutinin protein contained Q222 and G224 at the receptor-binding site. Although the neuraminidase protein contained I314V and the matrix 2 protein contained an S31N substitution, other mutations resulting in oseltamivir and amantadine resistance were not detected. No substitutions associated with increased virulence and enhanced transmission in mammals were detected in the polymerase basic protein 2 (627E and 701D). Non-structural-1 was 237 amino acids long and had an ESEV motif with additional RGNKMAD amino acids in the C terminal region. These viruses caused deaths in the Baikal teal, which was unusual, and outbreaks occurred at the same time in both poultry and wild birds. These data are helpful for epidemiological understanding of HPAI and the design of prevention strategies.

Separate and Combined Effect of Cadmium and Nickel on Blood Pressure in Rats / 예방의학회지

OBJECTIVE: To verify the separate and combined effects of cadmium and nickel on blood pressure in rats. METHODS: Following the daily administration of cadmium chloride(CdCl2) and nickel chloride(NiCl2) to rats both individually and in combination with intraperitoneal injection method for one week, systolic blood pressure of the tail was measured at 1 day and 5, 10, 20, 30 days after administration. Each substance was injected into the rats with 0.1 mg/kg bw and 1.0 mg/kg bw concentration. RESULTS: After 0.1 mg/kg bw CdCl2 was injected, a statistically significant difference was found as compared with the control group(only saline) after 1, 5 and 10 days. After 0.1 mg/kg bw NiCl2 was injected, a statistically significant difference was not found compared with the control group. After 0.1 mg/kg bw CdCl2 and 0.1 mg/kg bw NiCl2 were injected simultaneously, a statistically significant difference was found as compared with the control group after 1, 5 and 10 days and compared with 0.1 mg/kg bw CdCl2 group after 5 days and as compared with 0.1 mg/kg bw NiCl2 group after 5 and 10 days. After 1.0 mg/kg bw CdCl2 was injected, a statistically significant difference was found as compared with the control group after 1, 5, 10 and 20 days. After 1.0 mg/kg bw NiCl2 was injected, a statistically significant difference was found as compared with the control group after 1 day and 5 days. After 1.0 mg/kg bw CdCl2 and 1.0 mg/kg bw NiCl2 were injected in combination, a statistically significant difference was found after 1, 5, 10, 20 and 30 days as compared with 1.0 mg/kg bw CdCl2 after 10, 20 and 30 days and as compared with 1.0 mg/kg bw NiCl2 after 5, 10, 20 and 30 days. CONCLUSION: It was found that the effect of CdCl2 on blood pressure was much more than NiCl2 and a high concentration CdCl2 and NiCl2 in combination delayed the recovery of blood pressure.

Comparative Hepatotoxicity Assessment of Cadmium and Nickel with Isolated Perfused Rat Liver(IPRL) / 예방의학회지

OBJECTIVES: It is the objective of this study to compare hepatotoxicity of nickel chloride and cadmium chloride with each other through IPRL(Isolated Perfused Rat Liver) method. METHODS: Biochemical indicator of hepatic function such as AST(aspartate aminotransferase), ALT(alanine aminotransferase), LDH(lactate dehydrogenase) and perfusion flow rate were used as the indicator of hepatotoxicity. Oxygen consumption rate were used as viability indicator. 300(+/-50) g - weighted rats were allocated randomly to each group(0 micrometer, 50 micrometer, 200 micrometer NiCl2 and CdCl2 exposure) by 5, totally 25. After Krebs-Ringer bicarbonate buffer solution flowed into the portal vein and passed the liver cell, it flowed out of vena cava. Liver was administered with each NiCl2 and CdCl2 of each concentration and observed with buffer solution sampling time. Buffer which got out of liver was sampled and then biochemical indicator of hepatotoxicity was measured. RESULTS: AST, ALT, and LDH in buffer increased with sampling time much more in CdCl2 exposure group than NiCl2 exposure group in both 50 and 200 micrometer and statistical significance was verified with 2-way repeated ANOVA. Viability was decreased more and more in all substances during passed time. CONCLUSIONS: It is inferred that CdCl2 has stronger hepatotoxicity than NiCl2. IPRL method would be used widely for acute hepatotoxicity when considerating the benefit of it.

A Meta-analysis on the Association between Chronic Noise Exposure and Blood Pressure / 예방의학회지

OBJECTIVES: This study was conducted to integrate the results of studies assessing the association between chronic noise exposure and blood pressure. METHODS: Using a MEDLINE search with noise exposure, blood pressure and hypertension as key words, we retrieved articles from the literature that were published from 1980 to December 1999. The criteria for quality evaluation were as follows: 1) the study subjects must have been workers employed at a high noise level area 2) The paper should use average and cumulative noise exposure as method for exposure evaluation. 3) Blood pressure in each article should be reported in a continuous scale Among the 77 retrieved articles, six studies were selected for quantitative meta-analysis. Before the integration of the regression coefficients for the association between blood pressure and noise level, homogeneity tests were conducted. RESULTS: All studies were a cross-sectional design and the study subjects were industrial workers. Five papers used a time-weighted average for noise exposure and only one paper calculated the cumulative noise exposure level. The measurement of blood pressure in the majority of studies were accomplished in a resting state, and used an average of two or more readings. The homogeneity of studies was rejected in a fixed effect model, so we used the results in a random effect model. The results of the quantitative meta-analysis, the weighted regression coefficient of noise associated with systolic blood pressure and diastolic blood pressure were 0.05 (95% confidence interval [CI]: -0.03, 0.13) and 0.06 (95% CI: -0.01, 0.13), respectively. CONCLUSIONS: Our results suggested that chronic exposure to industrial noise does not cause elevated blood pressure.

The variation of thiodiglycolic acid concentration in urine with vinyl chloride exposure levels in rats / 대한산업의학회지

OBJECTIVES: It is the objective of this research to identify the variation of thiodiglycolic acid (TdGA) in urine with vinyl chloride monomer (VCM) exposure levels through methylation. METHODS: After rats were exposed to vinyl chloride monomer of 4 levels, 0 mg/m3, 50 mg /m3, 150 mg/m3, 500 mg/m3, respectively, of which urine was sampled in each sampling time of 0 hour, 2 hours, 4 hours, 8 hours, 16 hours, 24 hours, 36 hours, 48 hours. After urine had been methylated with diazomethane in the preliminary experiment and the peak of 146 m/z had been verified, the main experiment was done. RESULTS: In the variation of TdGA with sampling times, concentration of TdGA increased rapidly in 4 hours and then decreased after 8 hours. When the variation of urinary .TdGA concentration in urine according to exposure level of VCM was verified through Kruskal-Wallis statistical method at each sampling time, the significant increment with the exposure levels at 2 hours, 4 hours, 8 hours after exposure was clarified. CONCLUSION: TdGA concentration in urine with increment of VCM exposure level increased, especially significantly at 2 hours, 4 hours, 8 hours of sampling time.

What Factors Affect Mortality over the Age of 40? / 예방의학회지

OBJECTIVES: This study was conducted to identify the factors influencing the mortality of Koreans over the age of 40 by a nested case-control study. METHODS: The cohort consisted of the beneficiaries of Korea Medical Insurance Corporation for Government Employees & Private School Teachers and Staff(KMIC) who received health examinations of KMIC in 1992 and 1993 retrospectively. At that time, they were more than 40 years old. The cases were 19,258 cohort members who had died until December 31, 1997. The controls were 19,258 cohort members who were alive until December 31, 1997. Controls were matched with age and sex distribution of the cases. The data used in this study were the funeral expenses requesting files, and the files of health examinations and health questionnaires gathered in 1992 and 1993. To assess the putative risk factors of death, student t-test, chi-square test, multiple logistic regression analysis were used. RESULTS: In multiple logistic regression analysis, independent risk factors of death were as follows; systolic blood pressure, diastolic blood pressure, blood glucose, AST, urine glucose, urine protein, alcohol drinking(frequency), cigarette smoking and perceived health status, intake of restoratives and blood transfusion showed positive associations with death; coffee consumption showed negative associations with death; and body mass index and serum total cholesterol showed J-shaped association with death. CONCLUSIONS: Regarding the direction of association, the result of analysis on the data restricted to '96-'97 was same as that of '93-'97. But in some variables such as obesity, serum cholesterol, the odds ratios of death in the data of '96-'97 were higer than those of '93-'94, which suggested that the data of '93-'94 was bearing effect-cause relationship. We concluded that it suggested further researches using long-term follow-up data to be needed in this area.

Effect of Economic Depression on Psychosocial Distress of Industrial Workers / 대한산업의학회지

This study was carried out to assess the effect of economic depression on psychosocial distress, and to assess the relationship between differences of psychosocial distress and job characteristics (job strain), and to find out the effect of social support on psychosocial distress. We measured job characteristics(job demand, job control), and social support(coworker support, supervisor supports) at work by a self-administered questionnaire. Psychosocial distress was measured by PWI(Psychosocial Well-being Index), a 45-item self-administered instrument. Among the 152 respondents, the prevalence of high job strain was 27% (41 persons). The Odds ratio of high job strain was 3.11 (95% CI; 2.12~4.11), and those of passive group and active group were 2.01(95% CI; 0.83~2.76) and 1.80(95% CI; 0.83~2.76), respectively. Our results supported the association between psychosocial distress and job strain. The odds ratio of high strain isolates group (high strain group+low social support) was 3.59 (95% CI; 2.05~5.13), but the odds ratio of high strain collective group was 1.32 (95% CI; 0.23~2.41). Social support at work was modifying factor of the association between psychosocial distress and job strain. Therefore we reviewed the evidence that economic depression was associated with psychosocial distress in this study, and that the strength of the social support was important in maintain health.