Biodegradable (BP) poly(D,L-lactic acid) (PDLLA) membranes are widely used in tissue engineering. Here, we investigate the effects of varying concentrations of PDLLA/gelatin membranes electrospun in ...1,1,1,3,3,3-hexafluoro-2-propanol (HFIP; C
H
F
O) solvent on their mechanical and physical properties as well as their biocompatibility. Regardless of the environmental conditions, increasing the gelatin content resulted in elevated stress and reduced strain at membrane failure. There was a remarkable difference in strain-to-failure between dry and wet PDLLA/gelatin membranes, with wet strains consistently higher than those of the dry membranes because of the hydrophilic nature of gelatin. A similar wet strain (ε
= 2.7-3.0) was observed in PDLLA/gelatin membranes with a gelatin content between 10 and 40%. Both dry and wet stresses increased with increasing gelatin content. The dry stress on PDLLA/gelatin membranes (σ
= 6.7-9.7 MPa) consistently exceeded the wet stress (σ
= 4.5-8.6 MPa). The water uptake capacity (WUC) improved, increasing from 57% to 624% with the addition of 40% gelatin to PDLLA. PDLLA/gelatin hybrid membranes containing 10 to 20 wt% gelatin exhibited favorable wet mechanical properties (σ
= 5.4-6.3 MPa; ε
= 2.9-3.0); WUC (337-571%), degradability (11.4-20.2%), and excellent biocompatibility.
Environmental DNA (eDNA) analysis is a promising method for monitoring marine biodiversity. However, it is necessary to verify whether eDNA analysis provides an accurate measure of biodiversity in ...species-rich ecosystems such as coastal waters as part of a long-term monitoring campaign. Therefore, both an underwater visual census (UVC) and eDNA metabarcoding were conducted monthly from June 2018 to May 2019 to investigate fish diversity off the coast of Nodaedo Island, Tongyeong, South Korea. A total of 16,036 fish were observed in the UVC and classified into 69 species. Perciformes was the most dominant group with 31 species. eDNA metabarcoding identified 68 operational taxonomic units and 738,217 reads, encompassing 18 orders, 42 families, and 68 species. The Gobiidae family was the most dominant taxon with five species. The UVC was able to detect species that were otherwise not identified using eDNA due to the low number of individuals or analytical limitations, while eDNA metabarcoding was suitable for detecting smaller species, pelagic species, and those that inhabit microhabitats. Our findings demonstrated that these two methods can be used to complement each other and gain insights into the structure of fish communities in various coastal environments. Though eDNA metabarcoding represents a fast and efficient method for surveying fish species diversity in coastal waters, it should be carefully compared with other traditional survey methods to ensure that it is suitable as an effective complementary measure.
Polyvinyl alcohol (PVA)/carboxymethyl cellulose (CMC)/polyethylene glycol (PEG) hydrogel scaffolds are synthesized using cyclic freezing/thawing and subsequent γ‐ray irradiation to evaluate the ...effect of the molecular weights of PEG (200, 400, 1,000, and 2,000) on strength and cell growth behavior of the hydrogels. As the PEG weight increases from 200 to 2,000, the compressive strength and the pore size decreases gradually from 58.0 ± 8.2 kPa to 17.7 ± 6.1 kPa and from 22.7 ± 3.9 μm to 8.5 ± 1.6 μm, respectively. However, the highest swelling rate is obtained for PVA/CMC/PEG400 hydrogels. The irradiated PVA/CMC/PEG400 hydrogels exhibit tailored properties of the swelling rate of 1,148 ± 34.0%, the compressive strength of 42.5 ± 6.6 kPa, the pore size of 14.6 ± 1.9 μm, and cell viability of 184%. In addition, the fastest L‐929 cell proliferation and growth with time, verified by the cell proliferation (0–48 hr) and the scratch assay (0–15 hr), was observed for the PVA/CMC/PEG400 hydrogels, indicating that they are highly suitable for potential wound dressings that require fast healing regeneration.
The wound healing assay is a standard in vitro technique for probing collective cell migration in two dimensions. CC represents L‐929 cells only containing culture medium. The PVA/CMC/PEG hydrogels soaked with culture medium are designated as 200, 400, 1000, and 2000, respectively, depending on PEG molecular weight. The scratch assay of the PVA/CMC/PEG scaffolds suggests that the fastest cell migration into the cell‐free area is observed for the PVA/CMC/PEG400 hydrogel after 12 h.
We conducted a TS study of yellow croaker (Larimichthys polyactis), a major commercial fish in Asia that has not been studied before. Ours is the first study that examines the relationship between ...target strength (TS) and fish length using 38, 70, and 120 kHz split-beam echosounders. We measured TS in five size groups of yellow croaker (Larimichthys polyactis) based on length (8.2–26.5 cm total length) in a seawater tank and calculated the Kirchhoff-ray mode (KRM) model. When the slope of the least-squares regression line was forced to 20 in the TS equation, the resulting values for the constant term (b20) at each frequency (38, 70, and 120 kHz) using the caged method were –67.69, –67.52, and −68.83 dB, respectively. The swimming angle (mean ± S.D.) in the net cage was − 4.2 ± 21.9°. The b20 values for the KRM model were –65.01, –64.74, and −66.27 dB at 38, 70, and 120 kHz, respectively. In both methods, the KRM model’s b20 values were relatively higher than those of the caged method by 2.68, 2.78, and 2.56 dB at 38, 70, and 120 kHz, respectively. Such TS ex situ measurements can be applied to improve the yellow croaker’s acoustic abundance estimates.
Thermodynamically immiscible poly(lactic acid) (PLA) and poly(
ε
-caprolactone) (PCL) were blended and solution-cast by adding the 3% compatibilizer (tributyl citrate, TBC) of the PCL weight. In the ...PLA/PCL composition range of 99/1–95/5 wt%, mechanical properties of the PLA/PCL films with TBC were always superior to those of the films without TBC. The tensile strength of 42.9 ± 3.5 MPa and the elongation at break of 10.3 ± 2.7% were observed for the 93/7 PLA/PCL films without TBC, indicating that PCL addition is effective for strength and ductility. However, the tensile strength of 54.1 ± 3.4 MPa and the elongation at break of 8.8 ± 1.8% were found for the 95/5 PLA/PCL with TBC, indicating that the effect of co-addition of PCL and TBC on mechanical properties of the films is more pronounced. No cytotoxicity was observed for the PLA/PCL films regardless of TBC addition.
Acoustic-trawl surveys use trawl sampling to identify aquatic species. The Deep Vision stereo camera system collects images of fish passing through trawl extensions. We conducted a survey using Deep ...Vision with a mid-water trawl to identify and measure the lengths of domestic fish species in October 2020 and July 2021 in coastal waters off Jeju Island, Korea. We identified 86.4% of 22 species captured from images and estimated the lengths of 40% of the identified fish. A comparison of species numbers identified by mid-water trawl and Deep Vision revealed that, with the exception of three species with fewer than five individuals, identification was consistent. Our results indicate that the combined use of Deep Vision and mid-water trawl can be an eco-friendly and effective approach of examining the spatial distribution and size of fish species.
Metformin Inhibits Hepatic Gluconeogenesis Through AMP-Activated Protein Kinase–Dependent Regulation of the Orphan Nuclear
Receptor SHP
Yong Deuk Kim 1 ,
Keun-Gyu Park 2 ,
Yong-Soo Lee 1 ,
Yun-Yong ...Park 1 ,
Don-Kyu Kim 1 ,
Balachandar Nedumaran 1 ,
Won Gu Jang 3 ,
Won-Jea Cho 4 ,
Joohun Ha 5 ,
In-Kyu Lee 3 ,
Chul-Ho Lee 6 and
Hueng-Sik Choi 1
1 Hormone Research Center, School of Biological Sciences and Technology, Chonnam National University, Gwangju, Republic of Korea
2 Department of Internal Medicine, Keimyung University School of Medicine, Daegu, Republic of Korea
3 Department of Internal Medicine, Kyungpook National University School of Medicine, Daegu, Republic of Korea
4 College of Pharmacy and Research Institute of Drug Development, Chonnam National University, Gwangju, Korea
5 Department of Biochemistry and Molecular Biology, Medical Research Center for Bioreation to Reactive Oxygen Species, Kyung
Hee University College of Medicine, Seoul, Republic of Korea
6 Korea Research Institute of Bioscience and Biotechnology, Daejeon, Republic of Korea
Address correspondence and reprint requests to Hueng-Sik Choi, PhD, Hormone Research Center, School of Biological Sciences
& Technology, Chonnam National University, Gwangju, 500-757, Republic of Korea. E-mail: hsc{at}chonnam.ac.kr
Abstract
OBJECTIVE —Metformin is an antidiabetic drug commonly used to treat type 2 diabetes. The aim of the study was to determine whether metformin
regulates hepatic gluconeogenesis through the orphan nuclear receptor small heterodimer partner (SHP; NR0B2).
RESEARCH DESIGN AND METHODS —We assessed the regulation of hepatic SHP gene expression by Northern blot analysis with metformin and adenovirus containing
a constitutive active form of AMP-activated protein kinase (AMPK) (Ad-AMPK) and evaluated SHP, PEPCK, and G6Pase promoter
activities via transient transfection assays in hepatocytes. Knockdown of SHP using siRNA SHP was conducted to characterize
the metformin-induced inhibition of hepatic gluconeogenic gene expression in hepatocytes, and metformin–and adenovirus SHP
(Ad-SHP)–mediated hepatic glucose production was measured in B6- Lep ob/ ob mice.
RESULTS —Hepatic SHP gene expression was induced by metformin, 5-aminoimidazole-4-carboxamide-1-β- d -ribofuranoside (AICAR), and Ad-AMPK. Metformin-induced SHP gene expression was abolished by adenovirus containing the dominant
negative form of AMPK (Ad-DN-AMPK), as well as by compound C. Metformin inhibited hepatocyte nuclear factor-4α–or FoxA2-mediated
promoter activity of PEPCK and G6Pase, and the inhibition was blocked with siRNA SHP. Additionally, SHP knockdown by adenovirus
containing siRNA SHP inhibited metformin-mediated repression of cAMP/dexamethasone-induced hepatic gluconeogenic gene expression.
Furthermore, oral administration of metformin increased SHP mRNA levels in B6- Lep ob/ob mice. Overexpression of SHP by Ad-SHP decreased blood glucose levels and hepatic gluconeogenic gene expression in B6- Lep ob/ob mice.
CONCLUSIONS —We have concluded that metformin inhibits hepatic gluconeogenesis through AMPK-dependent regulation of SHP.
ACC, acetyl-CoA carboxylase
Ad-AMPK, adenovirus AMPK
Ad-DN-AMPK, adenovirus dominant negative form of AMPK
Ad-SHP, adenovirus SHP
AICAR, 5-aminoimidazole-4-carboxamide-1-β-d-ribofuranoside
AMPK, AMP-activated protein kinase
CA-AMPK, constitutively active AMPK
DMEM, Dulbecco's modified Eagle's medium
DN-AMPK, dominant negative mutant AMPK
GAPDH, glyceraldehyde-3-phosphate-dehydrogenase
HNF, hepatocyte nuclear factor
LRH-1, liver receptor homolog-1
SF-1, steroidogenic factor-1
SHP, small heterodimer partner
Footnotes
Published ahead of print at http://diabetes.diabetesjournals.org on 1 October 2007. DOI: 10.2337/db07-0381.
Additional information for this article can be found in an online appendix at http://dx.doi.org/10.2337/db07-0381 .
The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore
be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
Accepted September 26, 2007.
Received March 20, 2007.
DIABETES
Polyvinyl alcohol (PVA)/carboxymethyl cellulose (CMC) hydrogels containing various CMC concentration of 2 to 10 wt% are prepared using cyclic freezing/thawing and subsequent
γ
-ray irradiation to ...evaluate the effect of CMC content on cell growth rate of the hydrogels. A 3-D porous network structure is successfully formed
via
physical and chemical crosslinking. The pore size and the metronidazole drug release rate of the PVA/CMC hydrogels increase with raising the CMC concentration from 2 to 10 wt%, however, the structural integrity is severely damaged. The highest compressive strength of 99.2 ± 9.6 kPa and the fastest cell growth determined by scratch assay and enzyme-linked immunosorbent assay are observed for the irradiated PVA/6 wt% CMC hydrogels, indicating that they are highly suitable for wound dressing requiring fast regeneration.
Gelatin/polyvinyl alcohol (PVA) (g/P) porous hydrogels are chemically and physically crosslinked to evaluate the influence of the g/P weight ratio on the mechanical properties and cell adhesion ...behavior of the composite hydrogels. The degradation rate, pore size, and swelling rate of the g/P hydrogels decreased when the g/P ratio was lowered from 10/0 to 0/10 owing to the presence of PVA. Although the compressive strength increased with the increase in the PVA proportion in g/P hydrogels, no cell adhesion was observed in pure PVA due to the absence of ligands that bind to cell-surface receptors. Hydrogels with properties tailored for wound dressings can be obtained by adjusting the specific proportions of gelatin and PVA. We conclude that 5/5 and 7/3 g/P hydrogels can be applied as wound healing biomaterials because of their suitable mechanical properties, and their ability to facilitate rapid cell adhesion and proliferation.
Fibroblast growth factor 21 (FGF21) is a hormone that is vital for the regulation of metabolic homeostasis. In the present study, we report that Kruppel-like factor 15 (KLF15) is a novel mediator of ...b-cell translocation gene 2 (BTG2)-induced FGF21 biosynthesis. The expression levels of hepatic Fgf21, Btg2, and Klf15, and the production of serum FGF21 increased significantly in fasted and forskolin (FSK)-treated mice. The overexpression of Btg2 using an adenoviral delivery system elevated FGF21 production by upregulating Klf15 transcription. Interaction studies indicated that BTG2 was co-immunoprecipitated with KLF15 and recruited by the Fgf21 promoter. The disruption of hepatic Btg2 and Klf15 genes markedly attenuated the induction of Fgf21 expression and FGF21 biosynthesis in fasted mice. Similarly, the FSK-mediated induction of Fgf21 promoter activity was strikingly ablated by silencing of Btg2 and Klf15. Taken together, these findings suggest that KLF15 and BTG2 are mediators of fasting-induced hepatic FGF21 expression. Therefore, targeting BTG2 and KLF15 might be a therapeutically important strategy for combat metabolic dysfunction.
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