Analysis of changes in antibiotic resistance in the human body using an in vitro digestion model incorporating human gut microbiota.

Residual antibiotics may affect human health by increasing challenges related to infection treatment due to antibiotic resistance development. Hence, determining whether residual antibiotics in the body can lead to antibiotic resistance is important. We developed a model to predict possible antibiotic resistance caused by residual antibiotics by simulating human digestion in vitro. Increased antibiotic resistance was found to be dependent on the digestion process. Ethical prediction of antibiotic resistance using fewer animals and no humans was possible by simulating the internal environment. Thus, preliminary studies to monitor antibiotic resistance that can affect human health may be safely conducted using this model.

Study on the reduction of heterocyclic amines by marinated natural materials in pork belly.

This study was conducted to determine the effect of natural ingredient seasoning on the reduction of heterocyclic amine (HCA) production that may occur when pork belly is cooked at a very high temperature for a long time. Pork belly seasoned with natural ingredients, such as natural spices, blackcurrant, and gochujang, was cooked using the most common cooking methods, such as boiling, pan fry, and barbecue. HCAs in pork belly were extracted through solid-phase extraction and analyzed via high-performance liquid chromatography. For short-term toxicity, a mouse model was used to analyze weight, feed intake, organ weight, and length; hematology and serology analysis were also performed. Results revealed that HCAs formed only when heating was performed at a very high temperature for a long time, not under general cooking conditions. Although the toxicity levels were not dangerous, the method showing the relatively highest toxicity among various cooking methods was barbecue, and the natural material with the highest toxicity reduction effect was blackcurrant. Furthermore, seasoning pork belly with natural materials containing a large amount of antioxidants, such as vitamin C, can reduce the production of toxic substances, such as HCAs, even if pork belly is heated to high temperatures.

Main mechanisms for carcinogenic heterocyclic amine reduction in cooked meat by natural materials.

Carcinogens such as heterocyclic amine (HCA), produced during meat cooking, pose a risk of digestive and reproductive cancers in humans. Nevertheless, the exact mechanisms for HCA formation in meat and the control of HCA formation are not known. In this review, we provide an overview of the main cause of HCA formation in cooked meat, fundamental data on natural materials to inhibit HCA carcinogenicity, and methods to analyze HCA in cooked meat. Related past studies has shown that natural substances contain various components that act as antioxidants, and these antioxidants can prevent HCA and mutagenic factors. Free radicals and DNA adducts produced by HCA metabolism have carcinogenic properties. Antioxidants have been found to inhibit oxidative stress caused by free radicals and DNA adducts. Therefore, we can be hypothesized that various natural materials can inhibit HCA carcinogens and mutagens.

Analysis of in vitro digestion using human gut microbiota in adult and elderly individuals.

In vitro human digestion models are widely used to determine the digestibility of bioactive substances and to perform drug delivery analyses. To develop the most accurate in vitro human digestion model reported to date, we simulated all digestion conditions, including pH and digestion time, with changes in the amount of digestive enzymes, motility, and proportion of human gut microbiota in adult and elderly individuals. Using this newly developed model, the digestibility of vitamin E emulsified by lard was found to be significantly different between adults and the elderly. Therefore, this model can accurately simulate oral, gastric, and intestinal (with gut microbiota effects) digestion of bioactive substances and can aid in analyzing drug delivery in adults and elderly individuals.

Principal protocols for the processing of cultured meat.

The purpose of this study was to establish a basic principal procedure for the processing of cultured meat. The first stage involved isolating satellite cells from the desired muscle of an animal using enzymatic digestion (i.e., by using proteases, collagenases, and pronases). The second stage involved culturing the isolated muscle satellite cells in a growth medium containing fetal bovine serum and penicillin/streptomycin with growth factors for an optimal period of time. The second stage involved a basic method for the isolated muscle cells to proliferate while sub-culturing to further induce differentiation in gelatin-coated culture dishes with the general culture medium. The third stage involved the induction of differentiation of muscle satellite cells or formation of myotubes using myogenic medium. Lastly, the fourth stage involved the identification of cell differentiation or myotube formation (myogenesis) using fluorescent dyes. Moreover, the principle of these protocols can be applied to perform primary culture of animal cells. This study will assist beginners with the technical aspects of culturing meat (isolation, cultivation, and differentiation of muscle satellite cells as well as identification of myotube formation for myogenesis).

Differences in the gut microbiota between young and elderly persons in Korea.

The gut microbiota differs among countries owing to the prevailing diet composition. For the characterization of the gut microbiota of Koreans at different ages in future studies, e.g., in an in vitro human digestion model, we tried to investigate whether the gut microbiota differs between the young and elderly in Korea. Two hundred fecal samples were collected: 100 from elderly people (over 65 years old) at geriatric nursing hospitals and 100 from young people (university students, 20-25 years old) in Gyeonggi province, Korea. The composition of the gut microbiota in these fecal samples was analyzed by next-generation sequencing methods. There were significant differences in the taxonomic composition of the microbiota (the top 10 most abundant taxa) between the young and elderly people in Korea, especially in terms of relative abundance levels of bacteria in phyla Firmicutes, Proteobacteria, Tenericutes, and Fusobacteria (P < 001). The gut microbiota of young people contained higher relative abundance of Lactobacillus than did the microbiota of elderly people, while the microbiota of elderly people manifested higher relative abundance of Escherichia. Even though the sample size may not be large enough for this study to be representative of the entire population of Korea, the study still provides data that are suggestive of differences in the gut microbiota between young and elderly people in Korea. Furthermore, our findings may be applied to develop an improved age-based in vitro model of digestion of Koreans for future research.

Development of effective heparin extraction method from pig by-products and analysis of their bioavailability.

This study was conducted to develop an effective heparin extraction method by using low-cost and highly effective enzymes from six pig by-products (liver, lung, heart, stomach, small intestine, and large intestine), and analyze their bioavailability. Low-cost and highly effective enzymes (alkaline-AK and papain) and a common enzyme (trypsin) were used for the heparin extraction. The angiotensin I - converting enzyme (ACE) inhibitory activity and the antimicrobial activity of extracted heparin were analyzed to verify their bioavailability. The average amount of heparin extracted per kilogram of pig by-products was 439 mg from the liver, 127 mg from the lung, 398 mg from the heart, 261 mg from the stomach, 197 mg from the small intestine, and 239 mg from the large intestine. Various enzymes were used to extract heparin, and the amount of extracted heparin was similar. Based on 1 g of pig by-product, the enzymes trypsin, papain, and alkaline-AK could extract 1,718 mg, 1,697 mg, and 1,905 mg of heparin, respectively. Heparin extracted from pig by-products showed antihypertensive activity and antimicrobial activity against Staphylococcus aureus at low populations. These results indicated that heparin can be obtained from pig by-products at a low cost.

Overview of Studies on the Use of Natural Antioxidative Materials in Meat Products.

Studies conducted in the past decade related to the use of natural antioxidants in meat products revealed the prevalent use of plant-based antioxidative materials added as powders, extracts, or dried or raw materials to meat products. The amount of antioxidative materials varied from 7.8 ppm to 19.8%. Extracts and powders were used in small amounts (ppm to grams) and large amounts (grams to >1%), respectively. Antioxidative materials used in meat products are mainly composed of phenolic compounds and flavonoids, which are able to inhibit lipid peroxidation of meat products, thereby preserving meat quality. However, the main ingredients used in processed meat products are the traditional additives, such as sodium erythorbate, sodium hydrosulfite, and synthetic antioxidants, rather than natural antioxidants. This difference could be attributed to changes in the sensory quality or characteristics of meat products using natural antioxidants. Therefore, novel research paradigms to develop meat products are needed, focusing on the multifunctional aspects of natural antioxidants.

Effects of Six Different Starter Cultures on Mutagenicity and Biogenic Amine Concentrations in Fermented Sausages Treated with Vitamins C and E.

This study was performed to determine changes in mutagenicity and biogenic amine concentrations in sausages fermented with six different starter cultures treated with vitamins C and E. Six different types of fermented sausages with different combination of starter cultures were manufactured. T1, Pediococcus acidilactici; T2, P. pentosaceus and Staphylococcus carnosus; T3, S. carnosus, S. xylosus, Debaryomyces hansenii, Lactobacillus curvatus, and P. pentosaceus; T4, S. carnosus and L. sakei; T5, S. xylosus and L. plantarum; and T6, Penicillium nalgiovensis. After treatment with vitamins C and E in fermented sausages, changes in mutagenicity and biogenic amine concentrations were measured. The sausages fermented with Staphylococcus xylosus and Lactobacillus plantarum starter cultures showed the most effective antimutagenic activity (p<0.05). The mutagenicity was further decreased in the sausages treated with vitamins C and E (p<0.05), regardless of the starter cultures. The use of Pediococcus acidilactici, S. xylosus, L. plantarum, and Penicillium nalgiovensis as starter cultures was effective in decreasing biogenic amine concentrations (p<0.05). In addition, vitamin E was more effective in decreasing the biogenic amine concentrations than vitamin C. In conclusion, we recommend the use of S. xylosus and L. plantarum as starter cultures, in addition to the use of vitamins C and E, to reduce the potential risk of meat mutagens in fermented sausages.

Angiopoietin-like 4 is involved in the poor angiogenic potential of high glucose-insulted bone marrow stem cells.

BACKGROUND AND OBJECTIVES: Diabetes is reported to reduce the function or number of progenitor cells. We compared the gene expression patterns of bone marrow-derived mesenchymal stem cells from diabetic (DM-BMCs) and healthy (non-DM-BMCs) rats and suggested Angiopoietin-like 4 (Angptl4) could be a responsible factor for impaired angiogenesis of DM-BMCs. SUBJECTS AND METHODS: BMCs were isolated from DM or non-DM rat, and in vitro angiogenesis activity was compared by tube formation assay on Matrigel and complementary deoxyribonucleic acid expression was analyzed by microarray with or without oxytocin treatment. Human BMCs (hBMCs) were treated with high glucose, and were performed polymerase chain reaction, Western blot, and enzyme-linked immunosorbent assay. Angptl4 plasmid DNA and micro ribonucleic acid-132 (miR-132) were transfected to immortalized hBMCs. RESULTS: In vitro angiogenesis assay showed the impaired tube formation in DM-BMCs, and slightly recovery by oxytocin treatment. Angptl4, an adipokine, was upregulated in DM-BMCs compared to non-DM-BMCs. Oxytocin treatment reduced Angptl4 in DM-BMCs. In hBMCs, overexpression of Angptl4 attenuated the tube formation. In addition to Angptl4, miR-132 was increased by high glucose treatment. Collectively, high glucose resulted in impaired tube formation through miR-132 induction and Angptl4 upregulation in BMCs. CONCLUSION: Our results show that the angiogenic activity of BMCs is impaired by high glucose stress, which would be mediated by Angptl4 and miR-132.