Bog-Hieu Lee

Total Polyphenols, Total Flavonoid Contents, and Antioxidant Activity of Korean Natural and Medicinal Plants

The purpose of this study was to investigate total polyphenols, total flavonoid, and DPPH radical scavenging activity in 26 species of Korean natural plants and 14 species of medicinal plant extracts. The plant containing the highest total polyphenols and total flavonoids were Plantago asiatica, and Lespedeza cuneata G. Don, respectively. The content of polyphenols and flavonoids in natural plants was the highest in Lespedeza cuneata G. Don, which also demonstrated high DPPH radical scavenging activity. In medicinal plant extract, Saururus chinensis (Lour.) Baill and Artemisiae Asiaticae Herba had the highest level of total polyphenols (194.60 and 203.92 mg/g extract, respectively) and DPPH radical scavenging activity. Diospyros kaki Thunb and Dryopteris crassirhizoma did not contain high levels of total polyphenols (112.98, 121.46 mg/g extract, respectively) and flavonoids (46.10, 58.69 mg/g extract respectively), but DPPH radical scavenging activity was relatively high. Further study regarding plants that exhibit higher total polyphenols, total flavonoid, and DPPH radical scavenging activity is needed.

Comparison of the chemical compositions and nutritive values of various pumpkin (Cucurbitaceae) species and parts

Pumpkins have considerable variation in nutrient contents depending on the cultivation environment, species, or part. In this study, the general chemical compositions and some bioactive components, such as tocopherols, carotenoids, and β-sitosterol, were analyzed in three major species of pumpkin (Cucurbitaceae pepo, C. moschata, and C. maxima) grown in Korea and also in three parts (peel, flesh, and seed) of each pumpkin species. C. maxima had significantly more carbohydrate, protein, fat, and fiber than C. pepo or C. moschata (P < 0.05). The moisture content as well as the amino acid and arginine contents in all parts of the pumpkin was highest in C. pepo. The major fatty acids in the seeds were palmitic, stearic, oleic, and linoleic acids. C. pepo and C. moschata seeds had significantly more γ-tocopherol than C. maxima, whose seeds had the highest β-carotene content. C. pepo seeds had significantly more β-sitosterol than the others. Nutrient compositions differed considerably among the pumpkin species and parts. These results will be useful in updating the nutrient compositions of pumpkin in the Korean food composition database. Additional analyses of various pumpkins grown in different years and in different areas of Korea are needed.

Antiviral effect of korean red ginseng extract and ginsenosides on murine norovirus and feline calicivirus as surrogates for human norovirus.

Korean red ginseng has been studied various biological activities such as immune, anti-oxidative, anti-microbial, and anticancer activities but antiviral mechanism needs further studies. In this study, we aimed to examine the antiviral effects of Korea red ginseng extract and ginsenosides on norovirus surrogate, including murine norovirus (MNV) and feline calicivirus (FCV). We evaluated the pre-, co-, and post-treatment effects of Korean red ginseng (KRG), ginsenosides Rb1 and Rg1. To measure the antiviral effect and cytotoxicity of KRG extract, and ginsenosides Rb1 and Rg1, we treated Crandell-Reese Feline Kidney for FCV or RAW264.7 cells for MNV with concentrations of 0, 5, 6.7, 10, 20 ug/mL total saponin. There was cytotoxic effect in the highest concentration 20 ug/mL of KRG extract so this concentration was excluded in this study. The FCV titer was significantly reduced to 0.23-0.83 log10 50% tissue culture infectious dose (TCID50)/mL in groups pre-treated with red ginseng extract or ginsenosides. The titer of MNV was significantly reduced to 0.37-1.48 log10 TCID50/mL in groups pre-treated with red ginseng extract or ginsenosides. However, there was no observed antiviral effect in groups co-treated or post-treated with KRG and its constituents. Our data suggest that KRG extract has an antiviral effect against norovirus surrogates. The antiviral mechanisms of KRG and ginsenosides should be addressed in future studies.

Prevalence of Arcobacter Species Isolated from Retail Meats in Korea

This study was conducted to determine the prevalence of Arcobacter species identified or isolated from retail meats in Korea. Multiplex PCR assays for the detection of Arcobacter species were performed for 360 chicken, 100 pork, and 106 beef samples. Arcobacter butzleri and Arcobacter cryaerophilus were detected in 18.9 and 3.3% of chicken samples, respectively. However, Arcobacter species were not found in any of the pork and beef samples. Biochemical testing of isolates selected after enrichment revealed 38 A. butzleri isolates in chicken samples, but no A. cryaerophilus isolates were detected. In this study, A. butzleri was the most prevalent Arcobacter species in chicken meat, and contamination with Arcobacter species in pork and beef may be less prevalent in Korea.

Evidence of shedding of porcine circovirus type 2 in milk from experimentally infected sows.

Detection of porcine circovirus type 2 (PCV2) was to evaluate the milk from experimentally infected sows using polymerase chain reaction (PCR) and virus isolation. Six pregnant sows were inoculated intranasally with PCV2 at 93 days of gestation, and milk samples were collected from all sows at 1, 3, 6, 9, 12, 15, 18, 21, 24, and 27 days of lactation. PCV2 was detected in milk as early as day 1 of lactation in all six sows. Thereafter, all infected sows remained positive by PCR for PCV2 in milk until 27 days of lactation. In addition, PCV2 itself was isolated from milk collected from a virus-infected sows. These results suggest that PCV2 may be shed in milk following infection of pregnant sows by the virus.

Detection of Porcine Circovirus 2 in Mammary and Other Tissues from Experimentally Infected Sows

The aim of this study was to determine whether porcine circovirus 2 (PCV2) may infect the mammary gland of sows and be shed in the milk. Six pregnant sows were inoculated intranasally with PCV2 three weeks before their expected farrowing date and two further sows acted as uninfected controls. The animals remained clinically healthy and farrowed normally. Milk samples were collected from all sows on the first, second and third days of lactation. PCV2 DNA was detected in the milk of infected sows from day 1 of lactation but not in the milk of uninfected controls. PCV2 antigen and DNA were detected in the mammary gland and other tissues by immunohistochemistry and in-situ hybridization, respectively. Simultaneous detection of viral protein and DNA provided molecular evidence of PCV2 infection and replication within these tissues.

Relationship between Blood Mercury Level and Risk of Cardiovascular Diseases: Results from the Fourth Korea National Health and Nutrition Examination Survey (KNHANES IV) 2008-2009

Limited epidemiologic data is available regarding the cardiovascular effects of mercury exposure. The purpose of this study was to determine the relationship between mercury exposure from fish consumption and cardiovascular disease in a nationally representative sample of Korean adults using the Fourth Korea National Health and Nutrition Examination Survey (KNHANES IV 2008~2009). Survey logistic regression models accounting for the complex sampling were used to estimate the odds ratios (OR) adjusted for fish consumption frequency, age, education, individual annual income, household annual income, body mass index (BMI), waist circumference (WC), alcohol consumption status, and smoking status. The mean blood mercury level in the population was 5.44 μg/L. Trends toward increased blood mercury levels were seen for increased education level (P=0.0011), BMI (P<0.0001), WC (P<0.0001), and fish (i.e., anchovy) consumption frequency (P=0.0007). The unadjusted OR for hypertension in the highest blood mercury quartile was 1.450 [95% confidential interval (CI): 1.106~1.901] times higher than that of the lowest quartile. The fish consumption-adjusted OR for hypertension in the highest blood mercury quartile was 1.550 (95% CI: 1.131~2.123) times higher than that of the lowest quartile, and the OR for myocardial infarction or angina in the highest blood mercury quartile was 3.334 (95% CI: 1.338~8.308) times higher than that of the lowest quartile. No associations were observed between blood mercury levels and stroke. These findings suggest that mercury in the blood may be associated with an increased risk of hypertension and myocardial infarction or angina in the general Korean population.

Optimization of the elution buffer and concentration method for detecting hepatitis E virus in swine liver using a nested reverse transcription-polymerase chain reaction and real-time reverse transcription-polymerase chain reaction

The aim of this study was to develop an optimal technique for detecting hepatitis E virus (HEV) in swine livers. Here, three elution buffers and two concentration methods were compared with respect to enhancing recovery of HEV from swine liver samples. Real-time reverse transcription-polymerase chain reaction (RT-PCR) and nested RT-PCR were performed to detect HEV RNA. When phosphate-buffered saline (PBS, pH 7.4) was used to concentrate HEV in swine liver samples using ultrafiltration, real-time RT-PCR detected HEV in 6 of the 26 samples. When threonine buffer was used to concentrate HEV using polyethylene glycol (PEG) precipitation and ultrafiltration, real-time RT-PCR detected HEV in 1 and 3 of the 26 samples, respectively. When glycine buffer was used to concentrate HEV using ultrafiltration and PEG precipitation, real-time RT-PCR detected HEV in 1 and 3 samples of the 26 samples, respectively. When nested RT-PCR was used to detect HEV, all samples tested negative regardless of the type of elution buffer or concentration method used. Therefore, the combination of real-time RT-PCR and ultrafiltration with PBS buffer was the most sensitive and reliable method for detecting HEV in swine livers.

Evaluation of monoclonal antibody–based immunohistochemistry for the detection of European and North American Porcine reproductive and respiratory syndrome virus and a comparison with in situ hybridization and reverse transcription polymerase chain reaction

The objective of the present study was to compare the ability of 2 monoclonal antibodies (mAbs; SDOW17 and SR30) to detect types 1 and 2 Porcine reproductive and respiratory syndrome virus (PRRSV) in formalin-fixed, paraffin-embedded (FFPE) lung tissues by immunohistochemistry (IHC) and to compare the immunohistochemical results with in situ hybridization (ISH) and reverse transcription nested polymerase chain reaction (RT-nPCR) detection techniques. Lungs from 30 experimentally infected pigs (15 pigs with each genotype of PRRSV) and 20 naturally infected pigs (10 pigs with each genotype of PRRSV) with types 1 and 2 PRRSV, respectively, were used for the IHC, ISH, and RT-nPCR analyses. The SR30 mAb-based IHC detected significantly more type 1 PRRSV-positive cells in the accessory and caudal lobes from the experimentally infected pigs at 7 (P = 0.025) and 14 (P = 0.018) days postinoculation, respectively, compared to the SDOW17 mAb-based IHC. The results demonstrated that SR30 mAb-based IHC is useful for detecting both types 1 and 2 PRRSV antigen in FFPE lung tissues.

Expression of Mucins and Trefoil Factor Family Protein-1 in the Colon of Pigs Naturally Infected with Salmonella typhimurium

The expression patterns of different mucins (MUC1, MUC2, MUC4, MUC5AC, MUC5C and MUC6) and trefoil factor family protein-1 (TFF1) in the colon of healthy pigs and pigs naturally infected with Salmonella typhimurium is reported. Twenty infected pigs approximately 80-160 days of age from 20 different herds were studied. These animals had similar microscopical change in colonic tissue characterized by mucosal erosion or sloughing and acute inflammation. S. typhimurium was cultured from all lesions and the identity of each isolate was confirmed by serotyping. Immunohistochemical studies of colonic tissue revealed reduced expression of MUC4 on the surface of the cryptal epithelium of S. typhimurium-infected pigs compared with non-infected pigs (P<0.001). By contrast, colon from infected animals had increased expression of MUC5AC (P<0.0001) and TFF1 (P=0.0095) relative to controls and there was a significant positive correlation between expression of these two molecules (Spearman coefficient 0.64, P<0.0001). Further studies are needed to evaluate the functional relationship between altered expression of these molecules and inflammation in Salmonella-infected pigs.