Development of a method using QuEChERS and LC-MS/MS for analysis of per- and polyfluoroalkyl substances in rice matrix.

Detection of per- and polyfluoroalkyl substances (PFAS) in food is crucial for ensuring food safety. Therefore, we combined a quick, easy, cheap, rugged, and safe (QuEChERS) extraction method with liquid chromatography-triple-quadrupole mass spectrometry (LC-MS/MS) to detect 35 PFAS in rice. The solvents (water and acetonitrile) were adjusted to pH 2.4, a mixture of anhydrous MgSO4, NaCl, and NaOAc was used for extraction, and anhydrous MgSO4, a primary/secondary amine, and graphitized carbon black were applied for purification. The limits of detection and recovery were 0.005-0.100 ng·g-1 and 86.5 %-126.4 %, respectively. When this method was used to detect PFAS in packaged instant rice cooked in a microwave or boiled in water, the microwaved sample showed a lower PFAS content. However, both samples had PFAS contents within WHO guidelines and were safe for consumption. This method can be extended to detect PFAS levels in other foods exposed to packaging materials containing PFAS.

Prevalence and characterization of toxigenic Bacillus cereus group isolated from low-moisture food products.

The present study was conducted to determine the occurrence of B. cereus group members in low-moisture food products by phenotypic and genetic assessment and to evaluate the toxigenic potential of B. cereus group isolates. According to the results of their morphological shape, growth temperature range, strain-specific gene distribution, 79.5% and 20.5% among 112 isolates were identified as B. cereus sensu stricto (s.s.) and B. thuringiensis, respectively and other toxigenic B. cereus group members was not found. All B. cereus group isolates possessed nheABC, hblACD, cytK, entFM genes, and the most frequent gene was nheA. Only three B. cereus s. s. isolates exhibited as emetic toxin gene-harboring B. cereus group. Several B. cereus s.s. and B. thuringiensis isolates from a low-moisture food products were moderate biofilm formers and showed resistance to rifampicin, tetracycline, or clindamycin. The existence of B. cereus s.s. and B. thuringiensis in low-moisture food products indicates the possible risk of foodborne infections due to their virulence potential.

Changes in physicochemical properties and bacterial communities in aged Korean native cattle beef during cold storage.

During refrigerated storage, aged beef is liable to undergo alterations in its physicochemical properties. This study aimed to evaluate changes in the community of microorganisms, volatile compounds, and amino acids in aged beef under cold storage conditions. In addition, volatile basic nitrogen (VBN) values were measured to determine the putrefaction degree. Raw-, dry-, and wet-aged beef were stored at 4°C for 21 days. The initial pH of beef under the three conditions ranged from 5.52 to 5.60 and decreased from 5.04 to 5.33 over time. After 21 days, VBN values ranged 20.53-22.59 mg/100 g, which exceeded the standard of spoilage (20 mg/100 g) in the Korean Food Code. As time passed, numbers of psychrophilic and lactic acid bacteria increased in the raw beef. In contrast, number of mesophilic, psychrophilic, and lactic acid bacteria decreased in dry- and wet-aged beef. Among the volatile substances and amino acids, 2,3-butanedione, 2-butanone, tyrosine, and arginine contributed the most to the high VBN levels in aged beef, where the VBN was 21 mg/100 g at 21 days, which was beyond the acceptable limit. In conclusion, clear alterations were observed in the physicochemical properties and microorganism communities in cold-stored aged beef, providing basic information that could benefit the beef industry and boost consumer acceptance.

Shifts of microbiota during cheese production: impact on production and quality.

The high-throughput DNA sequencing (HTS) method is used to identify microbes in cheese and their potential functional properties. The technique can be applied to the microbiota of the cheese processing environment, raw milk, curd, whey, and starter cultures, and be used to improve the quality, safety, and other physicochemical properties of the final product. The HTS method is also utilized to study the microbiota shift of different types of cheeses during processing, as the composition and functional properties of the microbiome provide unique characteristics to different cheeses. Although there are several reviews that focused on microbiota of various types of cheeses, this review focuses on evaluating the microbiota shift of different types of cheese production and highlights key bacteria in each step of the processing as well as microbiota of various types of cheeses. KEY POINTS: • High-throughput sequencing can be applied to identify microbiota in cheese. • Microbiota in cheese is changed during making process and aging. • Starter culture plays an important role to establish microbiota in cheese.

Toxin gene profiles, genetic diversity, antimicrobial resistance, and coagulase type of Staphylococcus aureus from cream-filled bakery products.

We determined the toxin gene profile, toxin production, antibiotic resistance coagulase serotype, and genetic diversity of 42 coagulase-positive Staphylococcus aureus (CPS) isolates collected from 1,464 cream-filled bakery products in Korea. Among the CPS isolates, 37 (88.1%) produced enterotoxin genes in combination with another toxin; 26 (61.9%) of the strains were positive for sea, 1 (2.4%) for sea-seb, and 4 (9.5%) for sea-sec. Among the strains showing antibiotic resistance, 28 (66.7%) showed resistance to only one antibiotic, whereas nine (21.4%) showed resistance to multiple antibiotics: 4 (9.5%) strains were both mecA-positive and oxacillin-resistant. Most strains are resistant to at least one antibiotic-benzyl penicillin. The CPS isolates were classified into eight coagulase serotypes. This information will be valuable for assessing the capability risks of CPS food poisoning, contributing a better known of the epidemiology result associated with CPS contamination in bakery products.

Comparative evaluation of spoilage-related bacterial diversity and metabolite profiles in chilled beef stored under air and vacuum packaging.

Microbial spoilage is a complex event to which different bacterial populations and metabolites can contribute depending on the storage conditions. This study explored the evolution of spoilage and related volatile organic compounds (VOCs) in chilled beef under air and vacuum packaging (VP). The results suggested that different storage conditions affected changes in bacterial communities and metabolites in beef and consequently affected the odor properties of the stored beef, thereby leading to spoilage. Bacterial species belonging to Pseudomonadaceae (Pseudomonas spp.) and lactic acid bacteria (Lactobacillus sp.) dominated the bacterial communities in beef stored under air and VP, respectively, with several VOCs associated with off-odors of the stored beef and most likely produced by both bacteria. Our results suggested several microbial VOCs that could be used as potential spoilage indicators, including acetic acid, butanoic acid, and 2-butanone in VP-stored beef and 3-methylbutan-1-ol, ethyl acetate, acetoin, 2-butanone, and diacetyl in air-stored beef. These findings might provide valuable information regarding the quality monitoring of beef during storage.

Prevalence of Clostridium difficile isolated from various raw meats in Korea.

Clostridium difficile is an anaerobic, toxin-producing pathogen that causes human infection possibly through the consumption of meat. Clostridium difficile was isolated from 45 of 415 (10.8%) various raw meat samples collected in nationwide markets in Korea between 2013 and 2014. Among the 45 isolated strains, the highest prevalence rate was found in September (28.6%) and detected in chicken (16.4%), pork (8.3%) and beef (6.8%). According to an antibiotic resistance test, resistance was found only for clindamycin (2.2%). The genetic similarity of ribotypes O78 and O27 and strains isolated from raw meats was determined using DiversiLab. Among the isolates studied, four different rep-PCR types were identified, genetically distinct from ribotypes O78 and O27. An ELISA reaction confirmed that the two strains have toxin A and toxin B and showed 89% genetic similarity. This study suggests that food animals could be potential routes of foodborne transmission in C. difficile-associated human infection.

Antimicrobial susceptibility and serotyping of Listeria monocytogenes isolated from ready-to-eat seafood and food processing environments in Korea.

We examined antimicrobial susceptibility and serotypes of 33 L. monocytogenes isolates collected from ready-to-eat seafood and food processing environments. The isolated strains belonged to the 1/2b (73%), 4b (15%), and 1/2a (12%) serotypes; 11 of the obtained environmental swab samples belonged to the 1/2b serogroup. Antimicrobial resistance to benzyl penicillin (100%), clindamycin (100%), oxacillin (100%), ampicillin (97%), and tetracycline (18%) was detected, and 27/33 isolates (82%) showed resistance to four antibiotics and 6/33 (18%) were resistant to five. Total typing by automated repetitive sequence-based PCR revealed that the 33 isolates grouped into four distinct clusters with significantly correlated serotypes. These findings provide important information about the safety of ready-to-eat seafood and suggest that control measures should be adopted in order to mitigate the risk to humans posed by L. monocytogenes contaminated seafood.

Treatment of angiofibromas in tuberous sclerosis complex: the effect of topical rapamycin and concomitant laser therapy.

Facial angiofibromas are the most troublesome cutaneous manifestations of the tuberous sclerosis complex and are difficult to treat. Lasers are most commonly used to treat these skin lesions, but results are disappointing with frequent recurrences. Recently, treatment of facial angiofibromas with topical rapamycin has been reported to yield promising results. We observed the need of laser ablation in addition to topical rapamycin to get best results for the treatment of angiofibromas in 4 cases. The result showed that topical rapamycin ointment was enough when the papules were yet small in size, i.e. less than a few millimeters, but additional laser ablation was needed for large papules approximately larger than 4 mm. Considering the natural course of facial angiofibromas, we believe that topical rapamycin can be best used in childhood patients. In adults, topical rapamycin was useful for treating the still present small papules and for preventing recurrences after laser treatment.

The three dimensional conformal radiotherapy for hyperkeratotic plantar mycosis fungoides.

The localized early-stage of Mycosis fungoides (MF) (stage IA-IIA) is usually treated with topical agents, such as nitrogen mustard, steroids, and phototherapy (UVB/PUVA) as first line therapy; response to these initial treatments is usually good. However, hyperkeratotic plantar lesions are clinically rare and have decreased responsiveness to topical agents. For such cases, physicians may consider local radiotherapy. Here, a case of an 18-year-old Korean woman who was treated with three-dimensional conformal radiotherapy (3D-CRT) for hyperkeratotic plantar lesions that were refractory to UVA-1, methotrexate, and topical steroids is reported. Complete remission was attained after radiotherapy. During the one-year follow-up period, there has been no evidence of disease recurrence and no chronic complications have been observed.

Basal Cell Carcinoma on the Pubic Area: Report of a Case and Review of 19 Korean Cases of BCC from Non-sun-exposed Areas.

Basal cell carcinoma (BCC) is one of the most commonly diagnosed malignant skin tumors and develops characteristically on sun-exposed areas, such as the head and neck. Ultraviolet light exposure is an important etiologic factor in BCCs, and BCCs arising from non-sun- exposed areas are, therefore, very rare. In particular, the axilla, nipple, the genital and perianal areas are not likely to be exposed to ultraviolet light; thus, if BCC develops in these areas, other predisposing factors should be considered. Herein, we report a case of BCC arising on the pubic area in a 70-year-old man. We also performed a survey of the literature and discussed the 19 cases of BCC from non-sun-exposed areas reported to date in Korea.

Prevalence and antimicrobial resistance of Campylobacter jejuni and Campylobacter coli isolated from raw chicken meat and human stools in Korea.

Prevalence of Campylobacter in raw chicken meat and human stools and subsequent antibiotic resistance profiles of the pathogenic isolates obtained from 2000 through 2002 were investigated. Campylobacter jejuni and Campylobacter coli were isolated from 570 of the 923 raw chicken meat samples collected from traditional markets, large retail stores, or department stores in Korea, resulting in the isolation rate of 61.8%. A total of 579 Campylobacter isolates were obtained from raw chicken (36.3% for C. jejuni and 26.4% for C. coli) with the average population of 335.6 CFU/g. From 513 human stool samples, 15 isolates of Campylobacter were detected. Seasonal variation in the quantification of C. coli was not noticeable throughout the year, while the isolation rate of C. jejuni was the highest in September through October (840 CFU/g) followed by that of July through August and May through June in decreasing order, showing a significant seasonal effect (P < 0.05). Contamination of Campylobacter was more severe in raw chicken meat sold in traditional markets than in those sold in large retail stores and department stores. Prevalence of Campylobacter in raw chicken sold in traditional markets was significantly influenced by seasonal changes (P < 0.05), whereas the samples obtained from other places was less affected by the seasonal changes. Susceptibilities of the 594 chicken isolates to ciprofloxaxin, chloramphenicol, erythromycin, kanamycin, nalidixic acid, and tetracycline were determined by an E-test. Campylobacter isolates were the most resistant to nalidixic acid (91.4%) followed by ciprofloxaxin (87.9%), tetracycline (87.2%), kanamycin (30.6%), erythromycin (19.4%), and chloramphenicol (1.3%). Human isolates showed a similar resistance to the six antibiotics tested. The proportion of Campylobacter isolates with multidrug resistance to four or more antimicrobials obtained from 2000 through 2002 ranged from 28 to 43.5%, indicating that it could be a serious health-threatening factor. This study suggests that it is prudent to establish an effective National Monitoring Program in Korea for the prevention and control of Campylobacter spp.

Nerve root blocks in the treatment of lumbar radicular pain. A minimum five-year follow-up.

BACKGROUND: In a previous prospective, randomized, controlled, double-blinded study on the effect of nerve root blocks on the need for operative treatment of lumbar radicular pain, we found that injections of corticosteroids were more effective than bupivacaine for up to thirteen to twenty-eight months. We performed a minimum five-year followup of those patients who had avoided surgery. METHODS: All of the patients were considered to be operative candidates by the treating surgeon, and all had initially requested operative intervention. They had then been randomized to be treated with a selective nerve-root block with either bupivacaine or bupivacaine and betamethasone. Both the treating physician and the patient were blinded to the type of medication. Of fifty-five randomized patients, twenty-nine avoided an operation in the original study. Twenty-one of those twenty-nine patients were reevaluated with a follow-up questionnaire at a minimum of five years after the initial block. RESULTS: Seventeen of the twenty-one patients still had not had operative intervention. There was no difference between the group treated with bupivacaine alone and the group treated with bupivacaine and betamethasone with regard to the avoidance of surgery for five years. At the five-year follow-up evaluation, all of the patients who had avoided operative treatment had significant decreases in neurological symptoms and back pain compared with the baseline values. CONCLUSIONS: The majority of patients with lumbar radicular pain who avoid an operation for at least one year after receiving a nerve root injection with bupivacaine alone or in combination with betamethasone will continue to avoid operative intervention for a minimum of five years.

Development of adjacent-level ossification in patients with an anterior cervical plate.

BACKGROUND: It has been our experience that ossification occurs adjacent to anterior cervical plates. Our hypothesis was that the closer the plate is to the adjacent disc space, the greater the ossification. METHODS: We retrospectively reviewed the lateral radiographs of the cervical spine of 118 patients who had a solid fusion following an anterior cervical arthrodesis with a plate for the treatment of a degenerative cervical condition; none of the patients had had cervical spine surgery prior to the index arthrodesis. The plate-to-disc distance was measured on the postoperative lateral radiograph and was used to divide the patients into two groups for each of the two adjacent disc spaces. In group A the plate-to-disc distance was <5 mm, and in group B it was >/=5 mm. The mean duration of follow-up was 25.7 months. The severity of the ossification at the two adjacent disc spaces was classified on a scale ranging from grade 0 (no ossification) to grade 3 (complete bridging). Eighteen patients were excluded from the measurement of the severity of the caudal ossification because overlapping by the bone of the shoulder precluded adequate visualization of the caudal level. RESULTS: Ossification developed in seventy (59%) of the 118 cephalad adjacent disc spaces and twenty-nine (29%) of the 100 caudal adjacent disc spaces (p < 0.001). The mean cephalad plate-to-disc distance was shorter than the mean caudal plate-to-disc distance (p < 0.001). The rate of ossification was higher in group A than in group B, both at the cephalad adjacent disc spaces (67% compared with 24%) and at the caudal adjacent disc spaces (45% compared with 5%) (both p < 0.001). In addition, 93% (twenty-six) of the twenty-eight cases of moderate-to-severe ossification developed in group A. CONCLUSIONS: We found a positive association between adjacent-level ossification following anterior cervical plate procedures and the plate-to-disc distance. We now strive to place anterior cervical plates at least 5 mm away from the adjacent disc spaces in order to decrease the likelihood of moderate-to-severe adjacent-level ossification.

Expression of the mitochondrial ATPase6 gene and Tfam in Down syndrome.

We investigated the expression of the mitochondrial ATPase6 gene whose product is active in oxidative phosphorylation (OXPHOS), and compared it to the expression of Tfam, an important regulator of the transcription and replication of mtDNA. Our aim was to examine a possible relation between mitochondrial gene expression and Down syndrome. The expression of ATPase6 and Tfam was analyzed by RT-PCR amplification of the mRNA in cultured amniocytes from Down syndrome and normal fetuses. The band intensities obtained were normalized against those of HPRT. The Down syndrome fetuses were found to have lower ATPase6 and Tfam expression than the normal fetuses. This finding suggests that mitochondrial dysfunction resulting from decreased ATPase6 and Tfam expression during meiotic oocyte maturation of oocytes might affect ATP generation and cause the nondisjunctional error. Hence this study suggests that mitochondrial dysfunction may be associated with the developmental mechanism of Down syndrome.

Effects of methyl methacrylate on Ca2+ uptake of cardiac sarcoplasmic reticulum.

In isolated cardiac sarcoplasmic reticulum (SR) vesicles, methyl methacrylate (2.5-100mM) directly inhibited initial rates of Ca2+ uptake as well as the maximal uptake. Inhibition of SR Ca2+ uptake by methyl methacrylate was concentration-dependent, and the highest concentration of methyl methacrylate (100mM) almost completely inhibited the SR Ca2+ uptake. EC(50) of methyl methacrylate in percent inhibition of SR Ca2+ uptake was 16.1, 31.9, and 53.4mM at pCa 7.0, 6.6, and 6.0, respectively. At low Ca2+ concentrations (0.1-1 microM), SR vesicles treated with 20mM methyl methacrylate showed the decreased Ca2+ uptake rates. However, further increase of Ca2+ concentration to pCa 5.5 abolished the inhibitory effect of methyl methacrylate on SR Ca2+ uptake, showing no difference between the control and the methyl methacrylate-treated SR vesicles. From these results we could conclude that methyl methacrylate exerts a direct inhibition of cardiac SR Ca2+ uptake. This mechanism, at least in part, might contribute to the profound hypotension induced by methyl methacrylate. Supplementation of calcium ion appears to reduce the methyl methacrylate-induced cardiovascular disturbances efficiently.