Hyun-Jung Chung

Overview of Recent Events in the Microbiological Safety of Sprouts and New Intervention Technologies

There has been an increasing trend in consumption of sprouts worldwide due to their widespread availability and high nutrient content. However, microbial contamination of sprouts readily occurs due to the presence of pathogenic bacteria in seeds; and the germination and sprouting process provide optimal conditions for bacterial growth. In recent years, there has been a rise in the number of outbreaks associated with sprouts. These outbreaks occurred mainly in the US, Canada, UK, as well as Europe. More recently in 2011, there were 4 sprout-related outbreaks, with the Escherichia coli O104:H4 outbreak in Germany causing around 50 deaths and 4000 illnesses reported. On top of pathogenic E. coli, Salmonella spp. are often associated with sprout-related foodborne disease outbreaks. The contamination of sprouts has become a worldwide food safety concern. Hence, this review paper covers the outbreaks associated with sprouts, prevalence and characteristics of pathogens contaminating sprouts, their survival and growth, and the source of these pathogens. Physical, biological, and chemical interventions utilized to minimize microbial risks in sprouts are also discussed.

Growth temperature alters Salmonella Enteritidis heat/acid resistance, membrane lipid composition and stress/virulence related gene expression

The influence of growth temperature (10, 25, 37, and 42 °C) on the survival of Salmonella Enteritidis in simulated gastric fluid (SGF; pH=2.0) and during heat treatment (54, 56, 58, and 60 °C), on the membrane fatty acid composition, as well as on stress-/virulence-related gene expression was studied. Cells incubated at temperatures lower or higher than 37 °C did not increase their acid resistance, with the maximum D-value of 3.07 min in cells grown at 37 °C; while those incubated at higher temperature increased their heat resistance, with the maximum D60 °C-values of 1.4 min in cells grown at 42 °C. A decrease in the ratio of unsaturated to saturated fatty acids was observed as the growth temperature increased. Compared to the control cells grown at 37 °C, the expression of rpoS was 16.5- and 14.4-fold higher in cells cultivated at 10 and 25 °C, respectively; while the expression of rpoH was 2.9-fold higher in those cultivated at 42 °C. The increased expression of stress response gene rpoH and the decreased ratio of unsaturated to saturated fatty acids correlated with the greater heat resistance of bacteria grown at 42 °C; while the decreased expression of stress response gene rpoS at 42 °C might contribute to the decrease in acid resistance. Virulence related genes-spvR, hilA, avrA-were induced in cells cultivated at 42 °C, except sefA which was induced in the control cells. This study indicates that environmental temperature may affect the virulence potential of S. Enteritidis, thus temperature should be well controlled during food storage.

Surgery Versus Transarterial Chemoembolization for Solitary Large Hepatocellular Carcinoma of BCLC Stage A

Background/AimsThe aim of this study was to compare the outcomes of surgery and transarterial chemoembolization (TACE) for a solitary huge hepatocellular carcinoma (HCC) of Barcelona Clinic Liver Cancer (BCLC) stage A.MethodsOne hundred twenty-three consecutive patients with a solitary large (>5xa0cm) HCC classified at the BCLC stage A were analyzed. The posttreatment survival outcomes of patients that underwent surgery or TACE were compared.ResultsThe median age was 58xa0years (range, 29–90xa0years). The most common cause of HCC is hepatitis B virus infection (61.8xa0%). Median tumor size was 8.0xa0cm (range, 5.1–25xa0cm), and 97 patients (78.9xa0%) were of Child–Turcotte–Pugh class A. Median posttreatment follow-up duration was 18xa0months (range, 0.1–136xa0months). Of the 123 patients, 62 (50.4xa0%) underwent surgery and 61 (49.6xa0%) underwent TACE. Cumulative overall survival rates in the surgical group at 1, 3, and 5xa0years were significantly higher than those in the TACE group (83.2, 75.7, and 65.0xa0% vs 68.5, 45.0, and 17.5xa0%, respectively, Pu2009<u20090.01). In subgroup analysis, the cumulative overall survival in both surgical groups was significantly greater than in corresponding TACE subgroups (Pu2009=u20090.04 for ≥8-cm subgroup and Pu2009<u20090.01 for 5- to 8-cm-sized subgroups). Multivariate analysis showed that a larger tumor size (≥8xa0cm) (hazard ratio [HR] 2.14, Pu2009=u20090.02) was significantly associated with posttreatment mortality, whereas surgery (HR 0.37, Pu2009<u20090.01) compared with TACE was inversely associated with posttreatment mortality.ConclusionsSurgery may be the more effective treatment modality than TACE for a solitary large HCC of the BCLC stage A, regardless of tumor size.

The effects of Korean propolis against foodborne pathogens and transmission electron microscopic examination

This study was performed to evaluate the effects of Korean propolis against foodborne pathogens and spores of Bacillus cereus and to investigate the antimicrobial activity against B. cereus structure by transmission electron microscopy (TEM). The antimicrobial effects of the Korean propolis were tested against foodborne pathogens including Gram-positive (B. cereus, Listeria monocytogenes and Staphylococcus aureus) and Gram-negative (Salmonella typhimurium, Escherichia coli and Pseudomonas fluorescence) bacteria by agar diffusion assay. Gram-positive bacteria were more sensitive than were Gram-negative bacteria. The vegetative cells of B. cereus were the most sensitive among the pathogens tested with minimum inhibitory concentration (MIC) of 0.036 mg/μl of propolis on agar medium. Based on MIC, sensitivity of vegetative cells of B. cereus and its spores was tested in a nutrient broth with different concentrations of propolis at 37°C. In liquid broth, treatment with 1.8 mg/ml propolis showed bactericidal effect against B. cereus. B. cereus vegetative cells exposed to 7.2mg/ml of propolis lost their viability within 20 min. Against spores of B. cereus, propolis inhibited germination of spores up to 30 hours, compared to control at higher concentration than vegetative cells yet acted sporostatically. The bactericidal and sporostatic action of propolis were dependent on the concentration of propolis used and treatment time. Electron microscopic investigation of propolis-treated B. cereus revealed substantial structural damage at the cellular level and irreversible cell membrane rupture at a number of locations with the apparent leakage of intracellular contents. The antimicrobial effect of propolis in this study suggests potential use of propolis in foods.

Synergistic effect of high pressure processing and Lactobacillus casei antimicrobial activity against pressure resistant Listeria monocytogenes.

The purpose of this study was to evaluate combinations of high pressure processing (HPP) and Lactobacillus casei antimicrobial activity against Listeria monocytogenes strains with variation in pressure resistance in culture and in a food model. In culture, combination of HPP (350 MPa, for 1-20 min) and Lb. casei cell extract (CE, 32 CEAU/ml) showed a significant synergistic bactericidal effect (P<0.05) and the combination treatment decreased pathogens population >5 log(10)CFU/ml. Synergy between CE and HPP was most evident in the pressure-resistant strain, OSY-8578. Similar result was observed in meat products where high pressure (500 MPa for 1 min), and high-activity CE (100 CEAU/g) caused >5 log reduction in the viability of L. monocytogenes Scott A. The combination treatment resulted in the absence of peaks associated with cellular components in DSC thermogram suggesting that the presence of CE may have caused a considerable damage to cellular components during the high pressure treatment.

Effect of high hydrostatic pressure on the enzyme activities in Saccharomyces cerevisiae and Escherichia coli

The purpose of this study was to evaluate the effect of high hydrostatic pressure (HHP) on the enzyme activities in Saccharomyces cerevisiae (ATCC 16664) and Escherichia coli (ATCC 11229). Enzyme activities before and after HHP treatment were determined using an APIZYME enzyme assay kit. Thirteen active enzymes were detected in S. cerevisiae and E. coli. Pressure treatment at 448 MPa for 30s at 23 degrees C resulted in different effects on enzymes in S. cerevisiae and E. coli. HHP completely inactivated lipase, cystine arylamidase, and chymotrypsin and moderately inactivated esterase, esterase lipase, leucine arylamidase, valine arylamidase and alpha-glucosidase in S. cerevisiae. In E. coli, esterase, esterase lipase, lipase, valine arylamidase, cystine arylamidase, trypsin, alpha-glucosidase, and beta-glucuronidase were completely inactivated and leucine arylamidase and beta-galactosidase retained partial activities. Phosphoric hydrolases were not inactivated in both microorganisms. The use of the enzyme assay kit provided rapid and useful information on the microorganisms enzymes and their sensitivity to HHP treatment in a simple manner.

Transarterial chemoembolization versus surgery/radiofrequency ablation for recurrent hepatocellular carcinoma with or without microvascular invasion

Microvascular invasion (MVI) is a well‐known prognostic factor of postoperative recurrence and of overall survival (OS) in patients with hepatocellular carcinoma (HCC). We compared the treatment outcomes of transarterial chemoembolization (TACE) and surgery/radiofrequency ablation (RFA) according to the presence of MVI in patients with early or late recurrent HCC that presented as Barcelona Clinical Liver Cancer (BCLC) stage 0 or A after curative resection for HCC.

Antioxidative Activity of the n-Hexane Fractions from Spatholobus suberectus (SS), Scutellsria barbata (SB), Psoralea corylifolia (PC), Curcuma zedoaria (CZ), Schisandra chinensis (SC), and Corydalis turtschaninovii (CT)

LED-IT Fusion Technology Research Center, Yeungnam UniversityAbstract The objective of this study was carried out in order to evaluate the antioxidative activities of n-hexane fractionsfrom medicinal herbs. Certain parts from 6 species of edible and medicinal herbs were extracted with methanol. Radicalscavenging activity of the n-hexane fractions against DPPH and ABTS radicals were observed to be high in Psoraleacorylifolia, and Scutellsria barbata; it also significantly increased (p<0.05). For a comparison of the effect of variousconcentration of fractions, as the concentration of treatment increased, the antioxidative effects on radical scavengingactivity also oncreased; yet it was not significant. The antioxidative effect of medicinal plants was dependent on theconcentration but was not significant. Therefore, these results indicate that edible wild plants, such as Psoralea corylifolia,and Scutellsria barbata may be useful as potential antioxidant sources for improving the human antioxidant defense systemagainst disease.Keywords: ABTS radical, DPPH radical scavenging, free radical, Psoraleacorylifolia L., Schisandrachinensis

Usefulness of the Controlled Attenuation Parameter for Detecting Liver Steatosis in Health Checkup Examinees

Background/Aims The controlled attenuation parameter (CAP) implemented in FibroScan® is reported to be a non-invasive means of detecting steatosis (>10% steatosis). We aimed to evaluate the usefulness of CAP in detecting steatosis among health checkup examinees and to assess its correlation with ultrasonography (US). Methods Consecutive CAP results were retrospectively collected. A total of 280 subjects were included. Results Fatty liver was detected in 119 subjects (42.5%) by US, whereas it was detected in 160 subjects (57.1%) by the CAP. The numbers of subjects with S0:S1:S2:S3 steatosis according to the CAP value were 120:59:58:43, respectively. The mean CAP values were 203.34±28.39 dB/m for S0, 248.83±6.14 dB/m for S1, 274.33±8.53 dB/m for S2, and 322.35±22.20 dB/m for S3. CAP values were correlated with body weight (r=0.404, p<0.001), body mass index (r=0.445, p<0.001), and the fatty liver grade by US (r=0.472, p<0.001). Among the 161 subjects with normal US findings, steatosis was detected in 65 subjects (40.4%) using the CAP. Conclusions The CAP seems to be useful for detecting very low-grade hepatic steatosis in health checkup examinees. Its role in predicting subjects with a risk of metabolic derangement needs to be evaluated.

Prediction of sustained virologic response based on week 4 and week 12 response in hepatitis C virus genotype 1 patients treated with peginterferon and ribavirin: assessment in a favorable IL28B allele-prevalent area.

Objectives: The aim of this study was to evaluate rapid virologic response (RVR) rate after peginterferon (PegIFN) and ribavirin (RBV) dual combination therapy in Korean hepatitis C virus (HCV) genotype 1 patients whose IL28B polymorphism is generally favorable. This study also assessed the value of RVR in predicting sustained virologic response (SVR). Methods: Treatment-naïve HCV genotype 1 patients who underwent initial treatment with either PegIFN-α-2a or α-2b and RBV were retrospectively evaluated. From 148 patients, 115 met inclusion criteria for the final analysis. Results: Overall RVR rate was 47.8% and SVR rate was 67.8% (78/115). Positive RVR had the highest positive predictive value (PPV) for achieving SVR, whereas it had the lowest negative predictive value (NPV). Undetectable HCV RNA at treatment week 12, namely complete early virologic response (cEVR), had high PPV as well as high NPV. Factors predisposing SVR were absence of liver cirrhosis and achievement of RVR or cEVR. Conclusion: This study showed RVR rate close to 50% in HCV genotype 1 patients treated with dual combination therapy in the region where favorable IL28B polymorphism is reported to be as high as 90%. Even for the patients who failed to achieve RVR, positive cEVR demonstrated a fair chance of achieving SVR.