Process optimization for microfluidic preparation of liposomes using food-grade components.

This study explores the potential for optimizing a sustainable manufacturing process that maintains the essential characteristics of conventional liposomes using food-grade solvents and components. The focus was comparing the physicochemical, morphological, and interfacial properties of liposomes produced with these food-grade ingredients to those made by conventional methods. It was found that there was no significant difference in particle size (195.87 ± 1.40 nm) and ζ-potential (-45.13 ± 0.65 mV) between liposomes made from food-grade and conventional materials. The manufacturing process for liposomes, utilizing food-grade solvents and components, was optimized through the application of Plackett-Burman design and response surface methodology. This approach helped identify key parameters (soy lecithin, ß-sitosterol, W/O ratio) and their optimal values (3.17 g, 0.25 g, 1:2.59). These findings suggest that it is possible to enhance the use of liposomes as an effective and safe delivery system in the food industry, adhering to the strict guidelines set by regulatory agencies.

Performance feedback and obsessive passion: The moderating role of human capital.

Based on the behavioral theory of the firm, we research how performance feedback influences the formation of CEOs' passion. We articulate that previous performance directly increases CEOs' passion. Specifically, positive affective outcomes (performance above aspiration-level) advance CEOs' positive feelings and motivation toward the domains of success (obsessive passion). For instance, when a firm accomplishes performance objectives, such as reaching sales goals, CEOs' positive feelings toward developing current products would be boosted. Moreover, negative affective outcomes (performance below aspiration-level) would also positively impact CEOs' passion since the CEOs would endeavor to reduce the difference between performance and their aspiration-level. As such, performance feedback is a critical antecedent of CEOs' obsessive passion. In addition, we apply human capital as a moderator between performance feedback and CEOs' obsessive passion. Results based on multiphase survey data from 189 CEOs of Korean small- and medium-sized enterprises indicate that both positive and negative performance feedback positively increase CEOs' obsessive passion. Moreover, human capital negatively moderates the relationship between positive performance feedback and CEOs' obsessive passion and positively moderates the relationship between negative performance feedback and CEOs' obsessive passion.

Transplantation of Stem Cell Spheroid-Laden 3-Dimensional Patches with Bioadhesives for the Treatment of Myocardial Infarction.

Myocardial infarction (MI) is treated with stem cell transplantation using various biomaterials and methods, such as stem cell/spheroid injections, cell sheets, and cardiac patches. However, current treatment methods have some limitations, including low stem cell engraftment and poor therapeutic effects. Furthermore, these methods cause secondary damage to heart due to injection and suturing to immobilize them in the heart, inducing side effects. In this study, we developed stem cell spheroid-laden 3-dimensional (3D) patches (S_3DP) with biosealant to treat MI. This 3D patch has dual modules, such as open pockets to directly deliver the spheroids with their paracrine effects and closed pockets to improve the engraft rate by protecting the spheroid from harsh microenvironments. The spheroids formed within S_3DP showed increased viability and expression of angiogenic factors compared to 2-dimensional cultured cells. We also fabricated gelatin-based tissue adhesive biosealants via a thiol-ene reaction and disulfide bond formation. This biosealant showed stronger tissue adhesiveness than commercial fibrin glue. Furthermore, we successfully applied S_3DP using a biosealant in a rat MI model without suturing in vivo, thereby improving cardiac function and reducing heart fibrosis. In summary, S_3DP and biosealant have excellent potential as advanced stem cell therapies with a sutureless approach to MI treatment.

Biocatalytic nitric oxide generating hydrogels with enhanced anti-inflammatory, cell migration, and angiogenic capabilities for wound healing applications.

Although wound healing is a normal physiological process in the human body, it is often impaired by bacterial infections, ischemia, hypoxia, and excess inflammation, which can lead to chronic and non-healing wounds. Recently, injectable hydrogels with controlled nitric oxide (NO) release behaviour have become potential wound healing therapeutic agents due to their excellent biochemical, mechanical, and biological properties. Here, we proposed novel multifunctional NO-releasing hydrogels that could regulate various wound healing processes, including hemostasis, inflammation, cell proliferation and angiogenesis. By incorporating the copper nanoparticles (NPs) in the network of dual enzymatically crosslinked gelatin hydrogels (GH/Cu), NO was in situ produced via the Cu-catalyzed decomposition of endogenous RSNOs available in the blood, thus resolving the intrinsic shortcomings of NO therapies, such as the short storage and release time, as well as the burst and uncontrollable release modes. We demonstrated that the NO-releasing gelatin hydrogels enhanced the proliferation and migration of endothelial cells, while promoting the M2 (anti-inflammatory) polarization of the macrophage. Furthermore, the effects of NO release on angiogenesis were evaluated using an in vitro tube formation assay and in ovo chicken chorioallantoic membrane (CAM) assay, which revealed that GH/Cu hydrogels could significantly facilitate neovascularization, consistent with the in vivo results. Therefore, we suggested that these hydrogel systems would significantly enhance the wound healing process through the synergistic effects of the hydrogels and NO, and hence could be used as advanced wound dressing materials.

Composite Spheroid-Laden Bilayer Hydrogel for Engineering Three-Dimensional Osteochondral Tissue.

A combination of hydrogels and stem cell spheroids has been used to engineer three-dimensional (3D) osteochondral tissue, but precise zonal control directing cell fate within the hydrogel remains a challenge. In this study, we developed a composite spheroid-laden bilayer hydrogel to imitate osteochondral tissue by spatially controlled differentiation of human adipose-derived stem cells. Meticulous optimization of the spheroid-size and mechanical strength of gelatin methacryloyl (GelMA) hydrogel enables the cells to homogeneously sprout within the hydrogel. Moreover, fibers immobilizing transforming growth factor beta-1 (TGF-ß1) or bone morphogenetic protein-2 (BMP-2) were incorporated within the spheroids, which induced chondrogenic or osteogenic differentiation of cells in general media, respectively. The spheroids-filled GelMA solution was crosslinked to create the bilayer hydrogel, which demonstrated a strong interfacial adhesion between the two layers. The cell sprouting enhanced the adhesion of each hydrogel, demonstrated by increase in tensile strength from 4.8 ± 0.4 to 6.9 ± 1.2 MPa after 14 days of culture. Importantly, the spatially confined delivery of BMP-2 within the spheroids increased mineral deposition and more than threefold enhanced osteogenic genes of cells in the bone layer while the cells induced by TGF-ß1 signals were apparently differentiated into chondrocytes within the cartilage layer. The results suggest that our composite spheroid-laden hydrogel could be used for the biofabrication of osteochondral tissue, which can be applied to engineer other complex tissues by delivery of appropriate biomolecules.

Susceptibility of emetic and enterotoxigenic Bacillus cereus grown at high temperature to disinfectants.

The prevalence of emetic strains in food products is rare; however, infection with these may be fatal to the vulnerable population. Bacterial control of the emetic Bacillus cereus strains is still unclear. This study aimed to assess the influence of high temperature on the disinfection of emetic and enterotoxigenic B. cereus. Emetic B. cereus strains survived up to 50 °C; the lag time and maximum growth rate were higher at 42 °C than those at 30 °C. Compared to enterotoxigenic B. cereus, all emetic food strains showed higher minimum inhibitory concentrations and minimum bactericidal concentrations for sodium hypochlorite and citric acid. The disinfectant susceptibility of the emetic B. cereus OS-05 strain incubated at a higher temperature did not increase and was maintained at the highest MBC value. In all emetic B. cereus strains, enterotoxin gene expression was upregulated at 42 °C and 45 °C. Increased ces gene expression was also found in emetic B. cereus strains GP-15 and OS-05, with upregulation of 128- and 820-fold at 42 °C. Thus, emetic B. cereus grown at high temperatures may resist common disinfectants of the food industry. The findings may help control B. cereus in food or the food processing industry.

Actively cross-linking hemostatic sealant enables rapid hemostasis and wound closure.

A rapid hemostatic sealant can save a patient's life from shock and death due to severe trauma or excessive bleeding from the wound site during surgery. However, an ideal hemostatic sealant needs to meet the standards of safety, efficacy, usability, cost, and approvability and overcome new challenges. Here, we devised a combinatorial hemostatic sealant of PEG succinimidyl glutarate-based cross-linking branched polymers (CBPs) and the active hemostatic peptide (AHP). After ex vivo optimization, the best hemostatic combination was called an active cross-linking hemostatic sealant (ACHS). Interestingly, ACHS formed cross-links with serum proteins, blood cells, and tissue and interconnected coating on blood cells, which might induce hemostasis and tissue adhesion based on SEM images. Moreover, ACHS showed the highest coagulation efficacy, formation, and agglomeration of thrombi within 12 s, and in vitro biocompatibility. Mouse model experiments represented rapid hemostasis within 1 min, wound closure of the liver incision, and less bleeding than the commercialized sealant with tissue biocompatibility. ACHS has the advantages of rapid hemostasis, mild sealant, and easy supply by chemical synthesis without inhibition by anticoagulants, which might minimize bacterial infection by immediate wound closure. Therefore, ACHS could become a new-type hemostatic sealant to match surgical needs for internal bleeding.

Strongylidium koreanum n. sp. (Protozoa: Ciliophora), a new soil species from South Korea.

Strongylidium koreanum n. sp., a new soil ciliate from Jeju Island, South Korea, is described based on live observations, protargol impregnation, and molecular analysis of the 18S rRNA gene sequence. It is characterized by the following morphological features: cell outline more or less fusiform, posterior end broader than anterior end; grayish under low magnification; cortical granules absent; 23-32 adoral membranelles; three enlarged frontal cirri; buccal cirrus and postoral ventral cirrus present; 27-42 left and 15-28 right ventral cirri; 23-36 left and 30-46 right marginal cirri; three dorsal kineties; three caudal cirri; and two macronuclear nodules with two or three micronuclei. Phylogenetic analyses show that Strongylidium is monophyletic.

O2 variant chip to simulate site-specific skeletogenesis from hypoxic bone marrow.

The stemness of bone marrow mesenchymal stem cells (BMSCs) is maintained by hypoxia. The oxygen level increases from vessel-free cartilage to hypoxic bone marrow and, furthermore, to vascularized bone, which might direct the chondrogenesis to osteogenesis and regenerate the skeletal system. Hence, oxygen was diffused from relatively low to high levels throughout a three-dimensional chip. When we cultured BMSCs in the chip and implanted them into the rabbit defect models of low-oxygen cartilage and high-oxygen calvaria bone, (i) the low oxygen level (base) promoted stemness and chondrogenesis of BMSCs with robust antioxidative potential; (ii) the middle level (two times ≥ low) pushed BMSCs to quiescence; and (iii) the high level (four times ≥ low) promoted osteogenesis by disturbing the redox balance and stemness. Last, endochondral or intramembranous osteogenesis upon transition from low to high oxygen in vivo suggests a developmental mechanism-driven solution to promote chondrogenesis to osteogenesis in the skeletal system by regulating the oxygen environment.

Oxygen-supplying syringe to create hyperoxia-inducible hydrogels for in situ tissue regeneration.

Recent trends in the design of regenerative materials include the development of bioactive matrices to harness the innate healing ability of the body using various biophysicochemical stimuli (defined as in situ tissue regeneration). Among these, hyperoxia (>21% pO2) is a well-known therapeutic factor for promoting tissue regeneration, such as immune cell recruitment, cell proliferation, angiogenesis, and fibroblast differentiation into myofibroblast. Although various strategies to induce hyperoxia are reported, developing advanced hyperoxia-inducing biomaterials for tissue regeneration is still challenging. In this study, a catalase-immobilized syringe (defined as an Oxyringe) via calcium peroxide-mediated surface modification is developed as a new type of oxygen-supplying system. Hyperoxia-inducible hydrogels are fabricated utilizing Oxyringe. This hydrogel plays a role as a physical barrier for hemostasis. In addition, hyperoxic matrices induce transient hyperoxia in vivo (up to 46.0% pO2). Interestingly, the hydrogel-induced hyperoxia boost the initial macrophage recruitment and rapid inflammation resolution. Furthermore, hyperoxic oxygen release of hydrogels facilitates neovascularization and cell proliferation involved in the proliferation phase, expediting tissue maturation related to the remodeling phase in wound healing. In summary, Oxyringe has excellent potential as an advanced oxygen-supplying platform to create hyperoxia-inducing hydrogels for in situ tissue regeneration.

An improved method for rapid evaluation of enzymatic cis/trans isomerization of C18:1 monounsaturated fatty acids.

Cytochrome c-type cis/trans fatty acid isomerase (CTI) is a promising candidate for directly controlling cis/trans fatty acid isomerism in lipids-related food products like partially hydrogenated vegetable oils. In this study, to establish a sophisticated analysis platform for the CTI assay, we constructed the reversed micelle reaction system and improved the processes of methylation and GC-FID analysis of C18:1cis/trans monounsaturated fatty acid (MUFA) isomers. Highly stable AOT/isooctane reversed micelles were formed in the presence of periplasmic fractions of Pseudomonas putida KT2440. Using a mid-content cyanopropyl phase DB-FastFAME column, C18:1cis/trans-MUFAs were analyzed rapidly and resolved with resolution factors over 1.34. Based on the newly established assay, the catalytic activity of the periplasmic fraction was precisely determined, and its kinetic parameters (Vmax and Km) were derived as 0.021 mM·min-1 and 0.68 mM, respectively. The following results can provide practical information for investigating CTIs in the fields of food and lipid chemistry.

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.

Toxigenic Potential of Mesophilic and Psychrotolerant Bacillus cereus Isolates from Chilled Tofu.

The prevalence, toxin gene profile, antibiogram, and biofilm formation to determine the virulence potential of mesophilic and psychrotolerant Bacillus cereus (B. cereus) isolated from chilled tofu were investigated. Among 58 isolates, 21 isolates were capable of growth at 7 °C, and these isolates shared a potential hazard for food poisoning with mesophilic isolates. B. cereus harboring enterotoxin genes was more frequently found in psychrotolerant isolates than in mesophilic isolates. Thirty-seven (62.2%) mesophilic isolates and all psychrotolerant isolates carried four or more enterotoxin genes. The hemolysin BL (42.9%) and nonhemolytic enterotoxin complexes (90.5%) were found at a higher frequency in psychrotolerant isolates than in mesophilic isolates. Some B. cereus isolates showed resistance to rifampicin or clindamycin, regardless of mesophilic and psychrotolerant isolates. A total of 56% and 40% mesophilic isolates displayed the strongest biofilm formation at 40 and 42 °C, respectively. However, the biofilm formation of psychrotolerant isolates was not significantly affected by temperature. The results of this study provide new strategies for the development of bacterial control, which allows us to optimize technologies to inhibit B. cereus, including psychrotolerant isolates, in the food industry.

In situ graphene oxide-gelatin hydrogels with enhanced mechanical property for tissue adhesive and regeneration.

Extracellular matrix (ECM) is playing a critical role which is component of mammalian tissue that provide structural support to cells. In addition, ECM act as a local depot for growth factors that control cell phenotype and differentiation. In this regard, scaffold that mimicking the ECM structure is important to growth or wound healing process. Gelatin is natural polymer and derived from collagen which is a major component of ECM. Using gelatin as an ECM mimicking structure has advantage of providing three-dimensional growth or supporting to regulate the cell behavior, proliferation, migration, cell survival, and differentiation. In this study, we developed enzyme-mediated crosslinking gelatin-based hydrogels with robust mechanical property to mimicking ECM and effectively attach to the surrounding tissue with high adhesive property. The effect of different concentration of graphene oxide (GO) on the physico-chemical properties of gelatin hydrogels were investigated, particularly tissue adhesion strength. In vitro proteolytic degradation behavior and human dermal fibroblast proliferation study confirmed the hydrogels were biodegradable and promote cell proliferation. Overall, we suggest that GO incorporated gelatin hydrogels with additional interfacial interactions, showing a promising potential as an injectable tissue adhesive.

Controlled rate slow freezing with lyoprotective agent to retain the integrity of lipid nanovesicles during lyophilization.

We designed a novel lyophilization method using controlled rate slow freezing (CSF) with lyoprotective agent (LPA) to achieve intact lipid nanovesicles after lyophilization. During the freezing step, LPA prevented water supercooling, and the freezing rate was controlled by CSF. Regulating the freezing rate by various liquid media was a crucial determinant of membrane disruption, and isopropanol (freezing rate of 0.933 °C/min) was the optimal medium for the CSF system. Lyophilized lipid nanovesicle using both CSF and LPA retained 92.9% of the core material and had uniform size distributions (Z-average diameter = 133.4 nm, polydispersity index = 0.144), similar to intact vesicles (120.7 nm and 0.159, respectively), after rehydration. Only lyophilized lipid nanovesicle using both CSF and LPA showed no changes in membrane fluidity and polarity. This lyophilization method can be applied to improve storage stability of lipid nanocarriers encapsulating drugs while retaining their original activity.

Antimicrobial Effect of Acetic Acid, Sodium Hypochlorite, and Thermal Treatments against Psychrotolerant Bacillus cereus Group Isolated from Lettuce (Lactuca sativa L.).

Various food products distributed throughout the cold chain can present a health risk for consumers due to the presence of psychrotolerant B. cereus group species that possess enterotoxin genes and antibiotic resistance. As these bacteria can grow at the low temperatures used in the food industry, this study evaluated the antimicrobial efficacy of acetic acid, sodium hypochlorite, and thermal treatments for inhibition of psychrotolerant strains and the effect that differences in activation temperature (30 °C and 10 °C) have on their efficacy. The minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and bacterial growth assay of acetic acid and thermal treatment showed an equal or higher antimicrobial efficacy in isolates activated at 10 °C than in those activated at 30 °C. In particular, psychrotolerant strains from the B. cereus group were completely eliminated with 0.25% acetic acid, regardless of the activation temperature. The possibility of tolerance was determined by observing responses in cells activated at 10 and 30 °C when exposed to different concentrations of sodium hypochlorite. Five isolates activated at 10 °C exhibited enhanced survivability in sodium hypochlorite compared to isolates activated at 30 °C, and these isolates were able to grow in sodium hypochlorite at concentrations of 250 ppm or higher. Although a significant difference in antimicrobial efficacy was observed for psychrotolerant B. cereus group strains depending on the activation temperature, acetic acid may be the most effective antimicrobial agent against psychrotolerant B. cereus species isolated from food products distributed in a cold chain.

Morphological Features and Cold-Response Gene Expression in Mesophilic Bacillus cereus Group and Psychrotolerant Bacillus cereus Group under Low Temperature.

At low temperatures, psychrotolerant B. cereus group strains exhibit a higher growth rate than mesophilic strains do. However, the different survival responses of the psychrotolerant strain (BCG34) and the mesophilic strain (BCGT) at low temperatures are unclear. We investigated the morphological and genomic features of BCGT and BCG34 to characterize their growth strategies at low temperatures. At low temperatures, morphological changes were observed only in BCGT. These morphological changes included the elongation of rod-shaped cells, whereas the cell shape in BCG34 was unchanged at the low temperature. A transcriptomic analysis revealed that both species exhibited different growth-related traits during low-temperature growth. The BCGT strain induces fatty acid biosynthesis, sulfur assimilation, and methionine and cysteine biosynthesis as a survival mechanism in cold systems. Increases in energy metabolism and fatty acid biosynthesis in the mesophilic B. cereus group strain might explain its ability to grow at low temperatures. Several pathways involved in carbohydrate mechanisms were downregulated to conserve the energy required for growth. Peptidoglycan biosynthesis was upregulated, implying that a change of gene expression in both RNA-Seq and RT-qPCR contributed to sustaining its growth and rod shape at low temperatures. These results improve our understanding of the growth response of the B. cereus group, including psychrotolerant B. cereus group strains, at low temperatures and provide information for improving bacterial inhibition strategies in the food industry.

Effects of freezing rate on structural changes in L-lactate dehydrogenase during the freezing process.

Freezing is a common method for improving enzyme storage stability. During the freezing process, the freezing rate is an important parameter that can affect protein stability. However, there is limited information on the denaturation mechanisms and protein conformational changes associated with the freezing rate. In this study, the effects of freezing rate on activity loss and conformational changes in a model enzyme, L-lactate dehydrogenase, were evaluated. Enzyme solutions were frozen at various rates, from 0.2 to 70.6 °C/min, and ice seeding was conducted to reduce supercooling. The results demonstrated that fast freezing results in activity loss, structural changes, and aggregation. The residual activities at freezing rates of 0.2, 12.8, and 70.6 °C/min were 77.6 ± 0.9%, 64.1 ± 0.4%, and 44.8 ± 2.0%, respectively. As the freezing rate increased, the degree of dissociation and unfolding increased significantly, as determined using blue native-polyacrylamide gel electrophoresis and fluorescence spectroscopy. Moreover, a large number of amyloid aggregates were detected in samples frozen at a fast freezing rate (70.6 °C/min). The enzyme inactivation mechanism induced by fast freezing was proposed in terms of increased dehydration at the enzyme surface and an ice/unfroze solution interface, which could be helpful to establish a common understanding of enzyme inactivation during the freezing process.

Poly(amino ester)-Based Polymers for Gene and Drug Delivery Systems and Further Application toward Cell Culture System.

Various synthetic polymers based on poly(amino ester) (PAE) are suggested as candidates for gene and drug delivery owing to their pH-responsiveness, which contributes to efficient delivery performance. PAE-based pH-responsive polymers are more biodegradable and hydrophilic than other types of pH-responsive polymers. The functionality of PAE-based polymers can be reinforced by using different chemical modifications to improve the efficiency of gene and drug delivery. Additionally, PAE-based polymers are used in many ways in the biomedical field, such as in transdermal delivery and stem cell culture systems. Here, the recent novel PAE-based polymers designed for gene and drug delivery systems along with their further applications toward adult stem cell culture systems are reviewed. The synthetic tactics are contemplated and pros and cons of each type of polymer are analyzed, and detailed examples of the different types are analyzed.

Variables that prolong total operative time for robotic-assisted laparoscopic myomectomy: A 10-year tertiary hospital study in Korea.

STUDY OBJECTIVE: To identify factors that prolong total operative time (TOT) in robotic-assisted laparoscopic myomectomy (RALM). DESIGN: Retrospective cohort study. SETTING: Tertiary university hospital. PATIENTS: Women who underwent RALM between April 2009 and May 2019 conducted by a single high-volume gynecologic surgeon. INTERVENTIONS: Patients' demographic data and intraoperative records were obtained. The association between the perioperative characteristics and TOT was analyzed. MEASUREMENTS AND MAIN RESULTS: A total of 584 cases met the inclusion criteria, with a mean TOT of 231.6 ± 86.7 min. The mean patient age was 36.3 ± 5.5 years, and the patients had a mean of 4.2 ± 4.0 myomas. The dominant myoma had a mean diameter of 7.6 ± 2.6 cm. The mean total weight of the extracted myomas removed was 202.2 ± 152.6 g. From multiple regression analysis, the following perioperative factors were intimately associated with the TOT: ① body mass index, ② the number of myomas, ③ weight of total myomas, ④ location of dominant myoma, ⑤ type of da Vinci robot system, ⑥ endometrial cavity opening during the operation, ⑦ intraoperative blood loss, and ⑧ patient hospitalization period. The number of myoma was most closely related to the TOT, with an R2 value of 0.330. All of the above factors with the exception of the type of robot system and location of dominant myoma were related to the console time. Age, parity, history of previous abdominal surgery, surgical indication, diameter, and FIGO classification were not associated with the TOT. CONCLUSION: With an accurate identification of the perioperative parameters above, we can improve the quality of RALM by counselling, selecting an appropriate patient selection, and preoperative planning.