Anti-damage effect of theaflavin-3'-gallate from black tea on UVB-irradiated HaCaT cells by photoprotection and maintaining cell homeostasis

Keratinocytes are rich in lipids and are the main sensitive cells to ultraviolet (UV) rays. Theaflavins are the core functional components of black tea and are known as the "soft gold" in tea. In this study, ultraviolet-B (UVB) irradiation caused apoptosis and necrosis of human epidermal keratinocytes (HaCaT). EGCG and the four theaflavins had anti-UVB damage activity, among which theaflavin-3'-gallate (TF3'G) had the best activity. The results of biophysical and molecular biology experiments showed that TF3'G has anti-damage effects on UVB-irradiated HaCaT cells through the dual effects of photoprotection and maintenance of cell homeostasis. That is, TF3'G preincubation could absorb UV rays, reduce the accumulation of aging-related heterochromatin (SAHF) formation, increase mitochondrial membrane potential, downregulate NF-κB inflammation pathways, inhibit the formation of cytotoxic aggregates, and protect biological macromolecules Structure, etc. The accumulation of conjugated π bonds and the balance benzoquinone are the core functional structure of TF3'G with high efficiency and low toxicity. The study indicates that TF3'G has the potential to inhibit the photoaging and intrinsic aging of skin cells.

Ovalbumin antibody-based fluorometric immunochromatographic lateral flow assay using CdSe/ZnS quantum dot beads as label for determination of T-2 toxin

This work describes an anti-ovalbumin antibody-based lateral flow immunoassay (LFI) for T-2 toxin. The antibody uses a coating antigen as a bifunctional element for universality and introduces preincubation to improve the detection limits of the method. T-2 toxin and ovalbumin-modified T-2 toxin competitively binds on the anti-T-2 toxin monoclonal antibody modified on CdSe/ZnS quantum dot beads during preincubation. The modified T-2 toxin acts as a bifunctional element that forms immuno complexes during preincubation and combines with anti-ovalbumin antibody coated in the test line through the ovalbumin terminal. Fluorescence is detected at 610 nm on the test zone following photoexcitation at 365 nm. It has a reverse dose-effect relationship with the amount of T-2 toxin. The calibration plot is linear in the 20-110 fg mL^-1 T-2 toxin concentration range, and the limit of detection (LOD) is 10 fg mL^-1, which is lower by 8-fold than that of the traditional LFI system (LOD 80 fg mL^-1) and one order of magnitude than those of LFIs with labels of colloidal gold nanoparticles (LOD 150 fg mL^-1) or fluorophores (LOD 190 ng mL^-1). Universality was verified through aflatoxin B₁ detection using the established ovalbumin antibody-based LFI system (LOD 10 fg mL^-1). The performance of the method was compared with that of established systems and a commercial ELISA kit (LOD 360 fg mL^-1). Graphical abstractSchematic representation of ovalbumin antibody-based immunochromatographic lateral flow assay for T-2 toxin. Preincubation is introduced for high sensitivity. T-2- anti-ovalbumin acts as a bi-functional element for universality. CdSe/ZnS quantum dot beads act as label. Fluorometric signal is detected at 610 nm.

Kinetics of human cannabinoid 1 (CB1) receptor antagonists: Structure-kinetics relationships (SKR) and implications for insurmountable antagonism

While equilibrium binding affinities and in vitro functional antagonism of CB1 receptor antagonists have been studied in detail, little is known on the kinetics of their receptor interaction. In this study, we therefore conducted kinetic assays for nine 1-(4,5-diarylthiophene-2-carbonyl)-4-phenylpiperidine-4-carboxamide derivatives and included the CB1 antagonist rimonabant as a comparison. For this we newly developed a dual-point competition association assay with [³H]CP55940 as the radioligand. This assay yielded Kinetic Rate Index (KRI) values from which structure-kinetics relationships (SKR) of hCB1 receptor antagonists could be established. The fast dissociating antagonist 6 had a similar receptor residence time (RT) as rimonabant, i.e. 19 and 14 min, respectively, while the slowest dissociating antagonist (9) had a very long RT of 2222 min, i.e. pseudo-irreversible dissociation kinetics. In functional assays, 9 displayed insurmountable antagonism, while the effects of the shortest RT antagonist 6 and rimonabant were surmountable. Taken together, this study shows that hCB1 receptor antagonists can have very divergent RTs, which are not correlated to their equilibrium affinities. Furthermore, their RTs appear to define their mode of functional antagonism, i.e. surmountable vs. insurmountable. Finally, based on the recently resolved hCB1 receptor crystal structure, we propose that the differences in RT can be explained by a different binding mode of antagonist 9 from short RT antagonists that is able to displace unfavorable water molecules. Taken together, these findings are of importance for future design and evaluation of potent and safe hCB1 receptor antagonists.

Air-dried cells from the anhydrobiotic insect, Polypedilum vanderplanki, can survive long term preservation at room temperature and retain proliferation potential after rehydration

Pv11, a cell line derived from the anhydrobiotic insect, Polypedilum vanderplanki, was preserved in a dry form (only 6% residual moisture) at room temperature for up to 251 days and restarted proliferating after rehydration. A previous study already reported survival of Pv11 cells after desiccation, but without subsequent proliferation. Here, the protocol was improved to increase survival and achieve proliferation of Pv11 cells after dry storage. The method basically included preincubation, desiccation and rehydration processes and each step was investigated. So far, preincubation in a 600 mM trehalose solution for 48 h before dehydration was the most favourable preconditioning to achieve successful dry preservation of Pv11 cells, allowing about 16% of survival after rehydration and subsequent cell proliferation. Although the simple air-dry method established for Pv11 cells here was not applicable for successful dry-preservation of other insect cell lines, Pv11 is the first dry-preservable animal cell line and will surely contribute not only to basic but also applied sciences.

Comparison of Incubation Solutions Prior to the Purification of Porcine Islet Cells

For pancreatic islet transplantation, one of the most important steps of islet isolation is islet purification. The most common method of islet purification is density gradient centrifugation because there are differences in density between islets and acinar tissue. However, the density of islets/acinar tissue depends on several conditions, such as the incubation time before purification and the osmolality of the preincubation solution. In this study, we evaluated the impact of using two different preincubation solutions before purification. We used the University of Wisconsin (UW) solution and a new preservation solution (HN-1), which we recently developed. There were no significant differences between the two solutions in terms of the islet yield, rate of viability, and purity or stimulation index after purification. There were also no differences in the attainability and suitability of posttransplantation normoglycemia. Our study shows that the HN-1 solution is equivalent to the UW solution for preincubation before islet purification.

Growth dynamics of Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa as a function of time to detection in BacT/alert 3D blood culture bottles with various preincubation conditions

Background

Delayed entry of blood culture bottles is inevitable when microbiological laboratories do not operate for 24 hr. There are few studies reported for prestorage of these bottles. The growth dynamics of Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa were investigated with respect to various preincubation conditions.

Methods

Fifteen or 150 colony-forming units (CFU) of bacteria were inoculated into standard aerobic or anaerobic blood culture bottles. Bottles were preincubated at 25℃ or 37℃ for 0, 2, 4, 8, 12, 24, or 48 hr. The time to detection (TTD) then was monitored using the BacT/Alert 3D system (bioMerieux Inc., USA).

Results

Significant difference in TTD was observed following preincubation for 8 hr at 25℃ vs. 4 hr at 37℃ for S. aureus, 4 hr at 25℃ vs. 4 hr at 37℃ for E. coli, 12 hr at 25℃ vs. 4 hr at 37℃ for P. aeruginosa, compared to no preincubation (P<0.005). TTD values did not vary significantly with bacterial CFU or with aerobic or anaerobic bottle type. The BacT/Alert 3D system returned false negatives following preincubation of P. aeruginosa for 48 hr at 25℃ or 24 hr at 37℃.

Conclusions

TTD was mainly affected by preincubation temperature and duration rather than by input CFU quantity or bottle type for the 3 experimental bacteria.