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981.
Yen Mei Chow Beng Ti Tey Mohd Nordin Ibrahim Arbakariya Ariff Tau Chuan Ling 《Biotechnology and Bioprocess Engineering》2005,10(6):552-555
The influence of whole yeast cells (0–15% w/v) on the protein adsorption performance in dye-ligand chromatography was explored.
The adsorption of a model protein, bovine serum albumin (BSA), was selected to demonstrate this approach. The UpFront adsorbent
(ρ=1.5 g/cm3) derivatised with Cibacron Blue 3GA and a commercially available expanded bed column (20 mm i.d.) from UpFront Chromatography,
Denmark, were employed in the batch binding and expanded bed operation. The BSA binding capacity was demonstrated to not be
adversely affected by the presence of yeast cells. The dynamic binding capacity of BSA at aC/C
0=0..1 biomass concentration of 5, 10, 15% w/v were 9, 8, and 7.5 mg/mL of settled adsorbent, respectively. 相似文献
982.
Jia Hao Hao Zhou Kristen Nemes Daniel Yen Winfield Zhao Charles Bramlett Bowen Wang Rong Lu Keyue Shen 《The Journal of cell biology》2021,220(10)
Membrane-bound factors expressed by niche stromal cells constitute a unique class of localized cues and regulate the long-term functions of adult stem cells, yet little is known about the underlying mechanisms. Here, we used a supported lipid bilayer (SLB) to recapitulate the membrane-bound interactions between hematopoietic stem cells (HSCs) and niche stromal cells. HSCs cluster membrane-bound stem cell factor (mSCF) at the HSC-SLB interface. They further form a polarized morphology with aggregated mSCF under a large protrusion through a synergy with VCAM-1 on the bilayer, which drastically enhances HSC adhesion. These features are unique to mSCF and HSCs among the factors and hematopoietic populations we examined. The mSCF–VCAM-1 synergy and the polarized HSC morphology require PI3K signaling and cytoskeletal reorganization. The synergy also enhances nuclear retention of FOXO3a, a crucial factor for HSC maintenance, and minimizes its loss induced by soluble SCF. Our work thus reveals a unique role and signaling mechanism of membrane-bound factors in regulating stem cell morphology and function. 相似文献
983.
Enterohaemorrhagic Escherichia coli produces outer membrane vesicles as an active defence system against antimicrobial peptide LL‐37 下载免费PDF全文
Antimicrobial peptides (AMPs) are important components of the innate immune system. Enterohaemorrhagic Escherichia coli (EHEC), a food‐borne pathogen causing serious diarrheal diseases, must overcome attack by AMPs. Here, we show that resistance of EHEC against human cathelicidin LL‐37, a primary AMP, was enhanced by butyrate, which has been shown to act as a stimulant for the expression of virulence genes. The increase of resistance depended on the activation of the ompT gene, which encodes the outer membrane protease OmpT for LL‐37. The expression of the ompT gene was enhanced through the activation system for virulence genes. The increase in ompT expression did not result in an increase in OmpT protease in bacteria but in enhancement of the production of OmpT‐loaded outer membrane vesicles (OMVs), which primarily contributed to the increase in LL‐37‐resistance. Furthermore, a sublethal dosage of LL‐37 stimulated the production of OMVs. Finally, we showed that OMVs produced by OmpT‐positive strains protect the OmpT‐negative strain, which is susceptible to LL‐37 by itself more efficiently than OMVs from the ompT mutant. These results indicate that EHEC enhances the secretion of OmpT‐loaded OMVs in coordination with the activation of virulence genes during infection and blocks bacterial cell attack by LL‐37. 相似文献
984.
Chia-Yu Chang Yung-Hsin Yeh Yi-Hsin Chan Jia-Rou Liu Shang-Hung Chang Hsin-Fu Lee Lung-Sheng Wu Kun-Chi Yen Chi-Tai Kuo Lai-Chu See 《Cardiovascular diabetology》2017,16(1):159
Background
Whether dipeptidyl peptidase-4 inhibitor (DPP4i) is associated with a lower risk of new-onset atrial fibrillation (AF) in patients with diabetes remains unclear. This study aimed to evaluate the risk of AF associated with use of DPP4i among a longitudinal cohort of patients with diabetes.Methods
Over a 3-year period, 480,000 patients with diabetes were analyzed utilizing Taiwan’s National Health Insurance Research Database and 90,880 patients taking metformin as first-line therapy were enrolled. Patients were further divided into two groups: (1) DPP4i users: those taking DPP4i and (2) non-DPP4i users: those prescribed other hypoglycemic agents (HAs) as second-line drug. Study end point was defined by diagnosis of AF, addition of any third-line HA, or the end of the study period (December 31, 2013), whichever came first.Results
A total of 16,017 DPP4i users and 74,863 non-DPP4i users were eligible for the study. For the DPP4i group, most patients were prescribed sitagliptin (n = 12,180; 76%). Among the non-DPP4i group, most patients took sulfonylurea (n = 60,606; 81%) as their second-line medication. DPP4i users were associated with a lower risk of new-onset AF compared with non-DPP4i users after propensity-score weighting (hazard ratio 0.65; P < 0.0001). Subgroup analysis showed that DPP4i user were associated with a lower risk of new-onset AF compared with non-DPP4i users in most subgroups. Multivariate analysis indicated that use of DPP4i was associated with lower risk of new-onset AF and age > 65 years, presence of hypertension, and ischemic heart disease were independent risk factors for new-onset AF.Conclusions
Among patients with diabetes prescribed with metformin, the patients with DPP4i as second HA were associated with a lower risk of AF compared with the patients with other drugs as second HAs in real-world practice.985.
Background
Smad4 is a critical effector of TGF-β signaling that regulates a variety of cellular functions. However, its role in the brain has rarely been studied. Here, we examined the molecular mechanisms underlying the post-translational regulation of Smad4 function by SUMOylation, and its role in spatial memory formation.Results
In the hippocampus, Smad4 is SUMOylated by the E3 ligase PIAS1 at Lys-113 and Lys-159. Both spatial training and NMDA injection enhanced Smad4 SUMOylation. Inhibition of Smad4 SUMOylation impaired spatial learning and memory in rats by downregulating TPM2, a gene associated with skeletal myopathies. Similarly, knockdown of TPM2 expression impaired spatial learning and memory, while TPM2 mRNA and protein expression increased after spatial training. Among the TPM2 mutations associated with skeletal myopathies, the TPM2E122K mutation was found to reduce TPM2 expression and impair spatial learning and memory in rats.Conclusions
We have identified a novel role of Smad4 SUMOylation and TPM2 in learning and memory formation. These results suggest that patients with skeletal myopathies who carry the TPM2E122K mutation may also have deficits in learning and memory functions.986.
Su‐Yen Chang Ming‐Jen Cheng Chien‐Fang Peng Hsun‐Shuo Chang Ih‐Sheng Chen 《化学与生物多样性》2008,5(12):2690-2698
Three racemic butanolides, majorenolide ( 1 ), majorynolide ( 2 ), and majoranolide ( 3 ), with 18 known compounds, including ten butanolides, i.e., litsenolide A2 ( 4 ), litsenolide B2 ( 5 ), litsenolide C1 ( 6 ), litsenolide C2 ( 7 ), hamabiwalactone A ( 8 ), hamabiwalactone B ( 9 ), litseakolide A ( 10 ), litseakolide B ( 11 ), isoobtusilactone ( 12 ), and obtusilactone ( 13 ); one lignan, i.e., (±)‐syringaresinol ( 14 ), two flavans, i.e., (+)‐catechin ( 15 ), and (?)‐epicatechin ( 16 ), one coumarin, i.e., scopoletin ( 17 ), and four steroids, i.e., a mixture of β‐sitosterol ( 18 ) and stigmasterol ( 19 ), and a mixture of β‐sitosteryl‐3‐O‐β‐D ‐glucoside ( 20 ) and stigmasteryl‐3‐O‐β‐D ‐glucoside ( 21 ) were isolated from the root of Lindera akoensis. The structures of the isolates were elucidated by in‐depth spectroscopic analysis. Compounds 1 – 3 were previously assigned a δ‐lactone structure, which was then revised to a γ‐lactone structure, based on 1D‐NMR data. The cigar‐HMBC technique was used to confirm the accuracy of the γ‐lactone structure, and the zero [α] value of compounds 1 – 3 suggested that they were considerably racemized. Nine butanolides 1 – 3, 4 – 8 , and 10 showed antimycobacterial activities against M. tuberculosis H37Rv, with MIC values of 15–50 μg/ml. 相似文献
987.
Ow SY Cardona T Taton A Magnuson A Lindblad P Stensjö K Wright PC 《Journal of proteome research》2008,7(4):1615-1628
The filamentous cyanobacterium Nostoc sp. strain PCC 7120 is capable of fixing atmospheric nitrogen. The labile nature of the core process requires the terminal differentiation of vegetative cells to form heterocysts, specialized cells with altered cellular and metabolic infrastructure to mediate the N2-fixing process. We present an investigation targeting the cellular proteomic expression of the heterocysts compared to vegetative cells of a population cultured under N2-fixing conditions. New 8-plex iTRAQ reagents were used on enriched replicate heterocyst and vegetative cells, and replicate N2-fixing and non-N2-fixing filaments to achieve accurate measurements. With this approach, we successfully identified 506 proteins, where 402 had confident quantifications. Observations provided by purified heterocyst analysis enabled the elucidation of the dominant metabolic processes between the respective cell types, while emphasis on the filaments enabled an overall comparison. The level of analysis provided by this investigation presents various tools and knowledge that are important for future development of cyanobacterial biohydrogen production. 相似文献
988.
Yueh-Hsiang Yu Yi-Wen Lin Jane-Fang Yu Werner Schempp Pauline H Yen 《BMC evolutionary biology》2008,8(1):96
Background
The Azoospermia Factor c (AZFc) region of the human Y chromosome is a unique product of segmental duplication. It consists almost entirely of very long amplicons, represented by different colors, and is frequently deleted in subfertile men. Most of the AZFc amplicons have high sequence similarity with autosomal segments, indicating recent duplication and transposition to the Y chromosome. The Deleted in Azoospermia (DAZ) gene within the red-amplicon arose from an ancestral autosomal DAZ-like (DAZL) gene. It varies significantly between different men regarding to its copy number and the numbers of RNA recognition motif and DAZ repeat it encodes. We used Southern analyses to study the evolution of DAZ and AZFc amplicons on the Y chromosomes of primates. 相似文献989.
Ta-Chin Lin Jui-Mei Yen Tsung-Cheng Kuo Kun-Bing Gong Kung-Hao Hsu Teng-Tsao Hsu 《BMC biotechnology》2008,8(1):1-13
Background
Cryopreservation of preantral follicles or ovarian tissues would enable the storage of large numbers of primordial follicles or preantral follicles and preserves the structural integrity of somatic and reproductive cells. In the present study, we compared the developmental potential of cryopreserved two-week-old mouse preantral follicles, ovarian tissue slices, two-week-old mouse ovaries and newborn mouse ovaries using a metal plate with a high cooling rate for cooling the droplet of vitrification solution.Methods
Groups of 2 to 4 samples (including of 14-day old preantral follicles, ovarian tissue slices, whole ovaries, and whole newborn ovaries) were exposed to 4% ethylene glycol (EG) in DPBS + 10% FBS for 15 min and then rinsed in a vitrification solution composed of 6 M ethylene glycol and 0.4 M trehalose in DPBS + 10% FBS. Equilibration in room temperature was performed for 20–30 seconds for preantral follicle and 5 min equilibration was performed in an ice bath for ovaries. The samples were dropped onto the surface of metal plate around -180°C in the volume of 2 μl and 6 μl. After thawing, the ovarian tissue was mechanically isolated for collecting the preantral follicles. The thawed newborn ovaries were transplanted under the renal capsule of recipient male mice for 14 days. Preantral follicles collected from each groups were cultured individually in 20-μl droplets of α-MEM culture medium in culture dish for 12 days. On the day 12 of culture, the cumulus-oocyte complexes (COCs) were collected for IVM and IVF. Fertilization and embryo cleavage were scored.Results
After the vitrification of 14-day-old preantral follicles using 2 μl or 6 μl droplet onto surface of metal plate, the results indicated that no significant difference in survival rate, antral-like cavity formation, COCs collected, 2 cell embryo cleavage and blastocyst development was found in vitrification of the 2 μl and 6 μl droplet groups. As comparing 14-day old ovarian tissue (ovarian tissue slices and whole ovaries) and whole newborn ovaries vitrified in 6 μl droplet, lower success rates of antral-like cavity formation and COCs collection were found in the whole ovaries group.Conclusion
Our results suggest that the metal plate surface vitrification method is an appropriate and convenient method for cryopreservation of mouse ovaries and preantral follicles. The droplet volume of vitrification solution in 2 μl and 6 μl can be an option. 相似文献990.
Cellulose-graft-poly(N,N-dimethylamino-2-ethyl methacrylate) (cellulose-g-PDMAEMA) copolymers were prepared by homogeneous atom transfer radical polymerization (ATRP) under mild conditions. Cellulose macroinitiator was successfully synthesized by direct acylation of cellulose with 2-bromopropionyl bromide in a room temperature ionic liquid (RTIL), 1-allyl-3-methylimidazolium chloride. Copolymers were obtained via ATRP of N,N-dimethylamino-2-ethyl methacrylate (DMAEMA) with CuBr/pentamethyldiethylenetriamine (PMDETA) as catalyst and N,N-dimethylformamide (DMF) as solvent without homopolymer byproduct. The grafting copolymers were characterized by (1)H NMR, FT-IR, and TGA measurements. The results confirmed that PDMAEMA had been covalently bonded to cellulose backbone. Furthermore, the assemblies or aggregates formed by cellulose-g-PDMAEMA copolymers in water were studied at various concentrations, temperatures, and pH values by means of UV, DLS, TEM, and AFM. The results indicate that the copolymers had the pH- and temperature-responsive properties similar to the expected stimuli-responses by PDMAEMA. The synthetic strategy presented here could be employed in the preparation of other novel biomaterials from a variety of polysaccharides. 相似文献