Search Results (5)

One of the major drawbacks of the industrial implementation of enzymatic processes is the low operational stability of the enzymes under tough industrial conditions. In this respect, the use of thermostable enzymes in the industry is gaining ground during the last decades. Herein, we report a structure-guided approach for the development of novel and thermostable 2′-deoxyribosyltransferases (NDTs) based on the computational design of disulfide bonds on hot spot positions. To this end, a small library of NDT variants from Lactobacillus delbrueckii (LdNDT) with introduced cysteine pairs was created. Among them, LdNDT_S104C (100% retained activity) was chosen as the most thermostable variant, displaying a six- and two-fold enhanced long-term stability when stored at 55 °C (t_1/2^55 °C ≈ 24 h) and 60 °C (t_1/2^60 °C ≈ 4 h), respectively. Moreover, the biochemical characterization revealed that LdNDT_S104C showed >60% relative activity across a broad range of temperature (30–90 °C) and pH (5–7). Finally, to study the potential application of LdNDT_S104C as an industrial catalyst, the enzymatic synthesis of nelarabine was successfully carried out under different substrate conditions (1:1 and 3:1) at different reaction times. Under these experimental conditions, the production of nelarabine was increased up to 2.8-fold (72% conversion) compared with wild-type LdNDT. Full article

Objectives: Since the results of the RECOVERY trial, WHO recommendations about the use of corticosteroids (CTs) in COVID-19 have changed. The aim of the study is to analyse the evolutive use of CTs in Spain during the pandemic to assess the potential influence of new recommendations. Material and methods: A retrospective, descriptive, and observational study was conducted on adults hospitalised due to COVID-19 in Spain who were included in the SEMI-COVID-19 Registry from March to November 2020. Results: CTs were used in 6053 (36.21%) of the included patients. The patients were older (mean (SD)) (69.6 (14.6) vs. 66.0 (16.8) years; p < 0.001), with hypertension (57.0% vs. 47.7%; p < 0.001), obesity (26.4% vs. 19.3%; p < 0.0001), and multimorbidity prevalence (20.6% vs. 16.1%; p < 0.001). These patients had higher values (mean (95% CI)) of C-reactive protein (CRP) (86 (32.7–160) vs. 49.3 (16–109) mg/dL; p < 0.001), ferritin (791 (393–1534) vs. 470 (236–996) µg/dL; p < 0.001), D dimer (750 (430–1400) vs. 617 (345–1180) µg/dL; p < 0.001), and lower Sp0₂/Fi0₂ (266 (91.1) vs. 301 (101); p < 0.001). Since June 2020, there was an increment in the use of CTs (March vs. September; p < 0.001). Overall, 20% did not receive steroids, and 40% received less than 200 mg accumulated prednisone equivalent dose (APED). Severe patients are treated with higher doses. The mortality benefit was observed in patients with oxygen saturation </=90%. Conclusions: Patients with greater comorbidity, severity, and inflammatory markers were those treated with CTs. In severe patients, there is a trend towards the use of higher doses. The mortality benefit was observed in patients with oxygen saturation </=90%. Full article

Non-small-cell lung cancer (NSCLC) is the leading cause of cancer death worldwide. The high mortality is very often a consequence of its late diagnosis when the cancer is already locally advanced or has disseminated. Advances in the study of NSCLC tumors have been achieved by using in vivo models, such as patient-derived xenografts. Apart from drug screening, this approach may also be useful for study of the biology of the tumors. In the present study, surgically resected primary lung cancer samples (n = 33) were implanted in immunodeficient mice, and nine were engrafted successfully, including seven adenocarcinomas, one squamous-cell carcinoma, and one large-cell carcinoma. ADC tumors bearing the KRAS-G12C mutation were the most frequently engrafted in our PDX collection. Protein expression of vimentin, ezrin, and Ki67 were evaluated in NSCLC primary tumors and during serial transplantation by immunohistochemistry, using H-score. Our data indicated a more suitable environment for solid adenocarcinoma, compared to other lung tumor subtypes, to grow and preserve its architecture in mice, and a correlation between higher vimentin and ezrin expression in solid adenocarcinomas. A correlation between high vimentin expression and lung adenocarcinoma tumors bearing KRAS-G12C mutation was also observed. In addition, tumor evolution towards more proliferative and mesenchymal phenotypes was already observed in early PDX tumor passages. These PDX models provide a valuable platform for biomarker discovery and drug screening against tumor growth and EMT for lung cancer translational research. Full article

Structure-function relationships of a novel 2′-deoxyribosyltransferase from the psychrotolerant bacterium Bacillus psychrosaccharolyticus (BpNDT) have been exhaustively studied by biochemical and high resolution crystallographic analyses. Despite BpNDT exhibiting some structural features characteristic of cold-adapted enzymes such as localized flexibility in critical loops, its biochemical properties are typical of mesophilic enzymes. BpNDT is a highly symmetrical homohexamer with tightly associated subunits that possesses flexible and short loops bordering the active sites. The catalytic center is essentially identical to that of other mesophilic homologues. Moreover, BpNDT shows that it is a mesophilic-like enzyme since it is not heat-labile and exhibits an apparent unfolding temperature (T_m) of 49 °C, being active during 96 h at 40 and 50 °C. Finally, BpNDT synthesizes natural and modified nucleosides, with preference for purines as acceptors and pyrimidine nucleosides as donors. Remarkably, the synthesis of several therapeutic nucleosides has been efficiently carried out. In this sense, 5-hydroxymethyl-2′-deoxyuridine (5-HMdUrd), 7-deaza-6-hydroxypurine-2′-deoxyriboside (7-DHPdRib) and theophylline-2′-deoxyriboside were synthesized for the first time by an NDT enzyme, showing the biotechnological interest of BpNDT. Full article