Zobrazení zdroje stránky Lambbehrens4083

The tRNA modification N6-threonylcarbamoyladenosine (t6A) is universally conserved in all organisms. [https://www.selleckchem.com/products/AZD2281(Olaparib).html see more] In bacteria, the biosynthesis of t6A requires four proteins (TsaBCDE) that catalyze the formation of t6A via the unstable intermediate l-threonylcarbamoyl-adenylate (TC-AMP). While the formation and stability of this intermediate has been studied in detail, the mechanism of its transfer to A37 in tRNA is poorly understood. To investigate this step, the structure of the TsaBD heterodimer from Escherichia coli has been solved bound to a stable phosphonate isosteric mimic of TC-AMP. The phosphonate inhibits t6A synthesis in vitro with an IC50 value of 1.3 μM in the presence of millimolar ATP and L-threonine. The inhibitor binds to TsaBD by coordination to the active site Zn atom via an oxygen atom from both the phosphonate and the carboxylate moieties. The bound conformation of the inhibitor suggests that the catalysis exploits a putative oxyanion hole created by a conserved active site loop of TsaD and that the metal essentially serves as a binding scaffold for the intermediate. The phosphonate bound crystal structure should be useful for the rational design of potent, drug-like small molecule inhibitors as mechanistic probes or potentially novel antibiotics.<br /><br /> Papillary thyroid cancer (PTC) has been one of the most frequent endocrine malignancies around the world. Although most PTC patients have a favorable prognosis, a subgroup of patients die, especially when disease recurrence occurs. There is a pressing need for clinically relevant preclinical thyroid cancer models for personalized therapy because of the lack of in vitro models that faithfully represent the biology of the parental tumors.<br /><br /> To understand thyroid cancer and translate this knowledge to clinical applications, patient-derived PTC organoids as a promising new preclinical model were established.<br /><br /> Surgically resected PTC primary tissues were dissociated and processed for organoid derivation. Tumor organoids were subsequently subjected to histological characterization, DNA sequencing, drug screen, and cell proliferation assay, respectively.<br /><br /> We describe a 3-dimensional culture system for the long-term expansion of patient-derived PTC organoid lines. Notably, PTC organoids preserve the histopathological profiles and genomic heterogeneity of the originating tumors. Drug sensitivity assays of PTC organoids demonstrate patient-specific drug responses, and large correlations with the respective mutational profiles. Estradiol was shown to promote cell proliferation of PTC organoids in the presence of estrogen receptor α (ERα), regardless of the expression of ERβ and G protein-coupled ER.<br /><br /> These data suggest that these newly developed PTC-derived organoids may be an excellent preclinical model for studying clinical response to anticancer drugs in a personalized way, as well as provide a potential strategy to develop prevention and treatment options for thyroid cancer with ERα-specific antagonists.<br /><br />These data suggest that these newly developed PTC-derived organoids may be an excellent preclinical model for studying clinical response to anticancer drugs in a personalized way, as well as provide a potential strategy to develop prevention and treatment options for thyroid cancer with ERα-specific antagonists.<br /><br /> Elevating nicotinamide adenine dinucleotide (NAD+) levels systemically improves metabolic health, which can be accomplished via nicotinamide riboside (NR). Previously, it was demonstrated that NR supplementation in high-fat-diet (HFD)-fed mice decreased weight gain, normalized glucose metabolism, and enhanced cold tolerance.<br /><br /> Because brown adipose tissue (BAT) is a major source of thermogenesis, we hypothesize that NR stimulates BAT in mice and humans.<br /><br /> HFD-fed C56BL/6J mice were supplemented with 400 mg/kg/day NR for 4 weeks and subsequently exposed to cold. In vitro primary adipocytes derived from human BAT biopsies were pretreated with 50 µM or 500 µM NR before measuring mitochondrial uncoupling. Human volunteers (45-65 years; body mass index, 27-35 kg/m2) were supplemented with 1000 mg/day NR for 6 weeks to determine whether BAT activity increased, as measured by [18F]FDG uptake via positron emission tomography-computed tomography (randomized, double blinded, placebo-controlled, crossover study with NR supplementation).<br /><br /> NR supplementation in HFD-fed mice decreased adipocyte cell size in BAT. Cold exposure further decreased adipocyte cell size on top of that achieved by NR alone independent of ex vivo lipolysis. In adipocytes derived from human BAT, NR enhanced in vitro norepinephrine-stimulated mitochondrial uncoupling. However, NR supplementation in human volunteers did not alter BAT activity or cold-induced thermogenesis.<br /><br /> NR stimulates in vitro human BAT but not in vivo BAT in humans. Our research demonstrates the need for further translational research to better understand the differences in NAD+ metabolism in mouse and human.<br /><br />NR stimulates in vitro human BAT but not in vivo BAT in humans. Our research demonstrates the need for further translational research to better understand the differences in NAD+ metabolism in mouse and human.<br /><br /> Early growth is associated with childhood adiposity, but the influence of lifestyle remains unknown.<br /><br /> This work aimed to investigate the association of growth profiles from high-risk pregnancies with adiposity at age 5 years, taking into account lifestyle and several antenatal/postnatal exposures.<br /><br /> This prospective cohort study.<br /><br /> 609 children born during the Finnish Gestational Diabetes Prevention Study (RADIEL), recruiting women with body mass index (BMI) greater than or equal to 30 and/or prior gestational diabetes mellitus (GDM) (2008-2013). Altogether 332 children attended the 5-year follow-up (2014-2017). Main outcome measures included growth profiles based on ponderal index (PI = weight/height3), investigated using latent class mixed models. Adiposity was assessed with anthropometrics and body composition (InBody720).<br /><br /> We identified 3 growth profiles ascending (n = 82), intermediate (n = 351), and descending (n = 149). Children with ascending growth had a higher body fat percentage, ISO-BMI, and waist circumference (P &lt; .