concentration dependent manner
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2022 ◽  
Author(s):  
Richard W Davis ◽  
Charlotte Muse ◽  
Heather Eggleston ◽  
Micaila Hill ◽  
Peter Panizzi

Streptococcus pyogenes (S. pyogenes) can thrive in its host during an infection, and, as a result, it must be able to respond to external stimuli and available carbon sources. The pre-clinical use of engineered pathogens capable of constitutive light production may provide real-time information on microbial-specific metabolic processes. Here we mapped the central metabolism of a luxABCDE-modified S. pyogenes Xen20 (Strep. Xen20) to its de novo synthesis of luciferase substrates as assessed by the rate of light production in response to different environmental triggers. Previous characterization predicted that the lux operon was under the myo-inositol iolE promotor. Here we show that supplementation with myo-inositol generated increased Xen20 luminescence. Surprisingly, when supplemented with infection-relevant carbon sources, such as glucose or glycine, light production was diminished. This was presumably due to the scavenging of pyruvate by L-lactate dehydrogenase (LDH). Inhibition of LDH by its inhibitor, oxamate, partially restored luminescent signal in the presence of glucose, presumably by allowing the resulting pyruvate to proceed to acetyl-coenzyme A (CoA). This phenomenon appeared specific to the lactic acid bacterial metabolism as glucose or glycine did not reduce signal in an analogous luxABCDE-modified Gram-positive pathogen, Staph. Xen29. The Strep. Xen20 cells produced light in a concentration-dependent manner, inversely related to the amount of glucose present. Taken together, our measures of microbial response could provide new information regarding the responsiveness of S. pyogenes metabolism to acute changes in its local environments and cellular health.


Molecules ◽  
2022 ◽  
Vol 27 (2) ◽  
pp. 547
Author(s):  
Francine Medjiofack Djeujo ◽  
Valeria Francesconi ◽  
Maddalena Gonella ◽  
Eugenio Ragazzi ◽  
Michele Tonelli ◽  
...  

Diabetes mellitus is characterized by chronic hyperglycemia that promotes ROS formation, causing severe oxidative stress. Furthermore, prolonged hyperglycemia leads to glycation reactions with formation of AGEs that contribute to a chronic inflammatory state. This research aims to evaluate the inhibitory activity of α-mangostin and four synthetic xanthenone derivatives against glycation and oxidative processes and on α-glucosidase, an intestinal hydrolase that catalyzes the cleavage of oligosaccharides into glucose molecules, promoting the postprandial glycemic peak. Antiglycation activity was evaluated using the BSA assay, while antioxidant capacity was detected with the ORAC assay. The inhibition of α-glucosidase activity was studied with multispectroscopic methods along with inhibitory kinetic analysis. α-Mangostin and synthetic compounds at 25 µM reduced the production of AGEs, whereas the α-glucosidase activity was inhibited only by the natural compound. α-Mangostin decreased enzymatic activity in a concentration-dependent manner in the micromolar range by a reversible mixed-type antagonism. Circular dichroism revealed a rearrangement of the secondary structure of α-glucosidase with an increase in the contents of α-helix and random coils and a decrease in β-sheet and β-turn components. The data highlighted the anti-α-glucosidase activity of α-mangostin together with its protective effects on protein glycation and oxidation damage.


2022 ◽  
Author(s):  
Pei Xie ◽  
liying Zhang ◽  
Hui Shen ◽  
Hang Wu ◽  
Jiulong Zhao ◽  
...  

Abstract Exogenous antioxidant materials mimicking endogenous antioxidant systems are commonly used for the treatment of oxidative stress-induced injuries. Thus, artificial enzymes have emerged as promising candidates for balancing and treating the dysregulation of redox homeostasis in vivo. Herein, a one-pot hydrothermal strategy for the facile preparation of MoSe2@polyvinylpyrrolidone (PVP) nanoparticles (NPs) is reported. The synthesized NPs were biodegradable due to their exposure to oxygen and exhibited high stability. Moreover, they effectively mimicked various naturally occurring enzymes (including catalase, superoxide dismutase, peroxidase, and glutathione peroxidase) and scavenged free radicals, such as 3-ethylbenzothiazoline-6-sulfonic acid, ·OH, ·O2−, and 1,1-diphenyl-2-picrylhydrazyl radical. Further apoptosis detection studies revealed that MoSe2@PVP NPs significantly increased the cell survival probability in H2O2 in a concentration-dependent manner. The cytoprotective effect of MoSe2@PVP NPs was explored for an animal model of acute pancreatitis, which confirmed its remarkable therapeutic efficacy. Owing to the biodegradable and biocompatible nature of MoSe2@PVP NPs, the findings of this work can stimulate the development of other artificial nanoenzymes for antioxidant therapies.


2022 ◽  
Vol 23 (2) ◽  
pp. 865
Author(s):  
Jinsoo Kim ◽  
Dohee Ahn ◽  
Sang J. Chung

Depletion of protein phosphatase-1 catalytic subunit beta (PPP1CB), a serine/threonine protein phosphatase and potent adipogenic activator, suppresses the differentiation of 3T3-L1 preadipocytes into mature adipocytes. Therefore, PPP1CB is considered as a potential therapeutic target for obesity. We screened 1033 natural products for PPP1CB inhibitors and identified chebulinic acid, which is abundantly present in the seeds of Euphoria longana and fruits of Terminalia chebula. Chebulinic acid strongly inhibited the hydrolysis of 6,8-difluoro-4-methylumbelliferyl phosphate by PPP1CB (IC50 = 300 nM) and demonstrated potent antiadipogenic effects in 3T3-L1 preadipocytes in a concentration-dependent manner. Additional studies have demonstrated that chebulinic acid suppresses early differentiation by downregulating key transcription factors that control adipogenesis in 3T3-L1 cells. These results suggested that chebulinic acid may be a potential therapeutic agent for treating obesity by inhibiting PPP1CB activity.


2022 ◽  
Vol 12 ◽  
Author(s):  
Ryuichi Nakano ◽  
Yuki Yamada ◽  
Akiyo Nakano ◽  
Yuki Suzuki ◽  
Kai Saito ◽  
...  

Various carbapenemases have been identified in the Enterobacteriaceae. However, the induction and corresponding regulator genes of carbapenemase NmcA has rarely been detected in the Enterobacter cloacae complex (ECC). The NmcA-positive isolate ECC NR1491 was first detected in Japan in 2013. It was characterized and its induction system elucidated by evaluating its associated regulator genes nmcR, ampD, and ampR. The isolate was highly resistant to all β-lactams except for third generation cephalosporins (3GC). Whole-genome analysis revealed that blaNmcA was located on a novel 29-kb putatively mobile element called EludIMEX-1 inserted into the chromosome. The inducibility of β-lactamase activity by various agents was evaluated. Cefoxitin was confirmed as a strong concentration-independent β-lactamase inducer. In contrast, carbapenems induced β-lactamase in a concentration-dependent manner. All selected 3GC-mutants harboring substitutions on ampD (as ampR and nmcR were unchanged) were highly resistant to 3GC. The ampD mutant strain NR3901 presented with a 700 × increase in β-lactamase activity with or without induction. Similar upregulation was also observed for ampC and nmcA. NR1491 (pKU412) was obtained by transforming the ampR mutant (135Asn) clone plasmid whose expression increased by ∼100×. Like NR3901, it was highly resistant to 3GC. Overexpression of ampC, rather than nmcA, may have accounted for the higher MIC in NR1491. The ampR mutant repressed nmcA despite induction and it remains unclear how it stimulates nmcA transcription via induction. Future experiments should analyze the roles of nmcR mutant strains.


Author(s):  
Predrag Jevtić ◽  
K. Wade Elliott ◽  
Shelby E. Watkins ◽  
Jonathan A. Sreter ◽  
Katarina Jovic ◽  
...  

Cryoprotection is of interest in many fields of research, necessitating a greater understanding of different cryoprotective agents. Antifreeze proteins have been identified that have the ability to confer cryoprotection in certain organisms. Antifreeze proteins are an evolutionary adaptation that contributes to the freeze resistance of certain fish, insects, bacteria, and plants. These proteins adsorb to an ice crystal's surface and restrict its growth within a certain temperature range. We investigated the ability of an antifreeze protein from the desert beetle Anatolica polita, ApAFP752, to confer cryoprotection in the frog Xenopus laevis. X. laevis eggs and embryos microinjected with ApAFP752 exhibited reduced damage and increased survival after a freeze/thaw cycle in a concentration-dependent manner. We also demonstrate that ApAFP752 localizes to the plasma membrane in eggs and embryonic blastomeres and is not toxic for early development. These studies show the potential of an insect antifreeze protein to confer cryoprotection in amphibian eggs and embryos.


2022 ◽  
Vol 18 ◽  
Author(s):  
Vivian Cordeiro Rodrigues ◽  
William Queiroz Felippe ◽  
Carla Marins Goulart ◽  
Aurea Echevarria ◽  
Ana Paula Pereira da Silva

Background: Chalcones are open-chain flavonoids especially attractive to medicinal chemistry due to their easy synthesis and the possibility of structural modifications. Objective: Evaluate the in vitro anticancer activity of a series of hybrids chalcones-thiosemicarbazones against the human hepatocellular carcinoma cell line, HepG2. Methods: Seven hybrid chalcones-thiosemicarbazones (CTs), 3-(4’-X-phenyl)-1-phenylprop-2-en-1-one thiosemicarbazone, where X=H (CT-H), CH3 (CT-CH3), NO2 (CT-NO2), Cl (CT-Cl), CN (CT-CN), F (CT-F) and Br (CT-Br), were synthesized and their effects on cells viability and mitochondrial oxygen consumption were accessed. Results: Incubation with CTs caused a decrease in HepG2 cells viability in a time-concentration-dependent manner. The most effective compounds in inhibiting cell viability, after 24 hours of treatment, were CT-Cl and CT-CH3 (IC50 20.9 and 23.63 μM, respectively). In addition, using 10 M and only 1 hour of pre-incubation, CT-CH3 caused a reduction in basal respiration (-37%), oxygen consumption coupled with ATP synthesis (-60%) and maximum oxygen consumption (-54%). These alterations in respiratory parameters may be involved with the inhibitory effects of CT-CH3, since significant changes in oxygen consumption rates were observed in a condition that anticipates more significant losses of cell viability. The ADME parameters and the no violation of Lipinski Rule of Five showed that all compounds are safe. Conclusion: These results may contribute to the knowledge about the effects of CTs on these cells and the development of new treatments against HCCs.


Nanomaterials ◽  
2022 ◽  
Vol 12 (2) ◽  
pp. 191
Author(s):  
Rashmi Niranjan ◽  
Saad Zafar ◽  
Bimlesh Lochab ◽  
Richa Priyadarshini

Resistance to antimicrobial agents in Gram-positive bacteria has become a major concern in the last decade. Recently, nanoparticles (NP) have emerged as a potential solution to antibiotic resistance. We synthesized three reduced graphene oxide (rGO) nanoparticles, namely rGO, rGO-S, and rGO-S/Se, and characterized them using X-ray diffraction (PXRD), Raman analysis, and thermogravimetric analysis. Transmission electron microscopy confirmed spherical shape nanometer size S and S/Se NPs on the rGO surface. Antibacterial properties of all three nanomaterials were probed against Gram-positive pathogens Staphylococcus aureus and Enterococcus faecalis, using turbidometeric and CFU assays. Among the synthesized nanomaterials, rGO-S/Se exhibited relatively strong antibacterial activity against both Gram-positive microorganism tested in a concentration dependent manner (growth inhibition >90% at 200 μg/mL). Atomic force microscopy of rGO-S/Se treated cells displayed morphological aberrations. Our studies also revealed that rGO composite NPs are able to deposit on the bacterial cell surface, resulting in membrane perturbation and oxidative stress. Taken together, our results suggest a possible three-pronged approach of bacterial cytotoxicity by these graphene-based materials.


2022 ◽  
Vol 20 (1) ◽  
Author(s):  
Zhenzhen Yang ◽  
Anli Yang ◽  
Wang Ma ◽  
Kai Ma ◽  
Ya-Kun Lv ◽  
...  

Abstract Background Reactive oxygen species (ROS) have been widely studied for cancer therapy. Nevertheless, instability and aspecific damages to cellular biomolecules limit the application effect. Recently, significant research efforts have been witnessed in the flourishing area of metal nanoclusters (NCs) with atomically precise structures for targeted release of ROS but few achieved success towards targeting tumor microenvironment. Results In this work, we reported an atomically precise nanocluster Cu6(C4H3N2S)6 (Cu6NC), which could slowly break and generate ROS once encountered with acidic. The as-prepared Cu6NC demonstrated high biological safety and efficient chemodynamic anti-tumor properties. Moreover, Cu6NC enabled transient release of ROS and contained targeting behavior led by the tumor microenvironment. Both in vitro and in vivo experiments confirmed that Cu6NC demonstrated a low cytotoxicity for normal cells, while presented high cytotoxicity for tumor cells with a concentration-dependent manner. Conclusions This work not only reported a promising candidate for chemodynamic cancer therapy, but also paved the route to address clinical issues at the atomic level. Graphical Abstract


2022 ◽  
Author(s):  
Montaser F. Shaheen ◽  
Julie Y. Tse ◽  
Ethan S. Sokol ◽  
Margaret Masterson ◽  
Pranshu Bansal ◽  
...  

ABSTRACTBackgroundLymphatic malformations (LMs) often pose treatment challenges due to a large size or a critical location that could lead to disfigurement, and there are no standardized treatment approaches for either refractory or unresectable cases.MethodsWe examined the genomic landscape of a patient cohort of LMs (n=30 cases) that underwent comprehensive genomic profiling (CGP) using a large-panel next generation sequencing (NGS) assay. Immunohistochemical analyses were completed in parallel.ResultsThese LMs had low mutational burden with hotspot PIK3CA mutations and NRAS mutations being most frequent, and mutually exclusive. All LM cases with Kaposi sarcoma-like (kaposiform) histology had NRAS mutations. One index patient presented with subacute abdominal pain and was diagnosed with a large retroperitoneal lymphatic malformation harboring a somatic PIK3CA gain-of-function mutation (H1047R). The patient achieved a rapid and durable complete response to the PI3Kα inhibitor alpelisib within the context of a personalized N-of-1 clinical trial (NCT03941782). In translational correlative studies, canonical PI3Kα pathway activation was confirmed by immunohistochemistry and human LM-derived lymphatic endothelial cells carrying an allele with an activating mutation at the same locus were sensitive in vitro to alpelisib in a concentration-dependent manner.ConclusionsOur findings establish that LM patients with conventional or kaposiform histology have distinct, yet targetable, driver mutations.FundingR.P. and W.A. are supported by awards from the Levy-Longenbaugh Fund. S.G. is supported by awards from the Hugs for Brady Foundation. This work has been funded in part by the NCI Cancer Center Support Grants (CCSG; P30) to the University of Arizona Cancer Center (CA023074), the University of New Mexico Comprehensive Cancer Center (CA118100), and the Rutgers Cancer Institute of New Jersey (CA072720). B.K.M. was supported by National Science Foundation via Graduate Research Fellowship DGE-1143953.Clinical trial numberNCT03941782


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