Measuring Solution Viscosity and its Effect on Enzyme Activity

In proteins, some processes require conformational changes involving structural domain diffusion. Among these processes are protein folding, unfolding and enzyme catalysis. During catalysis some enzymes undergo large conformational changes as they progress through the catalytic cycle. According to Kramers theory, solvent viscosity results in friction against proteins in solution, and this should result in decreased motion, inhibiting catalysis in motile enzymes. Solution viscosity was increased by adding increasing concentrations of glycerol, sucrose and trehalose, resulting in a decrease in the reaction rate of the H(+)-ATPase from the plasma membrane of Kluyveromyces lactis. A direct correlation was found between viscosity (η) and the inhibition of the maximum rate of catalysis (V (max)). The protocol used to measure viscosity by means of a falling ball type viscometer is described, together with the determination of enzyme kinetics and the application of Kramers’ equation to evaluate the effect of viscosity on the rate of ATP hydrolysis by the H(+)-ATPase

LAS PROTEÍNAS EN LA NUTRICIÓN

Las proteínas son biomoléculas presentes en los organismos vivos y llevan a cabo gran parte de las actividades celulares. Estas biomoléculas están formadas por 20 aminoácidos (aa) específicos en diferentes proporciones, los cuales son requeridos en diversas cantidades para formar o sintetizar una proteína dada. En los humanos, el organismo puede sintetizar algunos aa sin necesidad de obtenerlos de afuera y son llamados aminoácidos no esenciales. Sin embargo algunos de estos aa no los puede producir por sí solo y necesita obtenerlos del exterior (la alimentación) para así poder sintetizar proteína. Los aa son requeridos por nuestro organismo en diferentes proporciones, según la edad, actividad física y condición fisiológica. Dado que el organismo sintetiza proteína corporal con todos los aminoácidos esenciales, basta que haya uno en poca cantidad o ausente, para que la síntesis se vea afectada. No obstante, la combinación de alimentos que contengan alguno de los aminoácidos faltantes así como su digestibilidad en el organismo dará una excelente aportación de estos nutrimentos al organismo. Palabras Clave: proteínas, aminoácidos esenciales, digestibilidad, proteínas alimentarias, Calidad de las proteínas.proteins, essentials amino acids, digestibility, diet protein, quality proteins.

Engineering and Directed Evolution of a Ca2+ Binding Site A-Deficient AprE Mutant Reveal an Essential Contribution of the Loop Leu75–Leu82 to Enzyme Activity

An aprE mutant from B. subtilis 168 lacking the connecting loop Leu75–Leu82 which is predicted to encode a Ca2+ binding site was constructed. Expression of the mutant gene (aprEΔLeu75–Leu82) produced B. subtilis colonies lacking protease activity. Intrinsic fluorescence analysis revealed spectral differences between wild-type AprE and AprEΔL75–L82. An AprEΔL75–L82 variant with reestablished enzyme activity was selected by directed evolution. The novel mutations Thr66Met/Gly102Asp located in positions which are predicted to be important for catalytic activity were identified in this variant. Although these mutations restored hydrolysis, they had no effect with respect to thermal inactivation of AprEΔL75–L82 T66M G102D. These results support the proposal that in addition to function as a calcium binding site, the loop that connects β-sheet e3 with α-helix c plays a structural role on enzyme activity of AprE from B. subtilis 168

Population-based colorectal cancer screening programmes using a faecal immunochemical test:Should faecal haemoglobin cut-offs differ by age and sex?

Abstract Background The Basque Colorectal Cancer Screening Programme has both high participation rate and high compliance rate of colonoscopy after a positive faecal occult blood test (FIT). Although, colorectal cancer (CRC) screening with biannual (FIT) has shown to reduce CRC mortality, the ultimate effectiveness of the screening programmes depends on the accuracy of FIT and post-FIT colonoscopy, and thus, harms related to false results might not be underestimated. Current CRC screening programmes use a single faecal haemoglobin concentration (f-Hb) cut-off for colonoscopy referral for both sexes and all ages. We aimed to determine optimum f-Hb cut-offs by sex and age without compromising neoplasia detection and interval cancer proportion. Methods Prospective cohort study using a single-sample faecal immunochemical test (FIT) on 444,582 invited average-risk subjects aged 50–69 years. A result was considered positive at ≥20 μg Hb/g faeces. Outcome measures were analysed by sex and age for a wide range of f-Hb cut-offs. Results We analysed 17,387 positive participants in the programme who underwent colonoscopy. Participation rate was 66.5%. Men had a positivity rate for f-Hb of 8.3% and women 4.8% (p < 0.0001). The detection rate for advanced neoplasia (cancer plus advanced adenoma) was 44.0‰ for men and 15.9‰ for women (p < 0.0001). The number of colonoscopies required decreased in both sexes and all age groups through increasing the f-Hb cut-off. However, the loss in CRC detection increased by up to 28.1% in men and 22.9% in women. CRC missed were generally at early stages (Stage I-II: from 70.2% in men to 66.3% in women). Conclusions This study provides detailed outcomes in men and women of different ages at a range of f-Hb cut-offs. We found differences in positivity rates, neoplasia detection rate, number needed to screen, and interval cancers in men and women and in younger and older groups. However, there are factors other than sex and age to consider when consideration is given to setting the f-Hb cut-off

Polymorphisms within the TNFSF4 and MAPKAPK2 Loci influence the risk of developing invasive aspergillosis: A two-stage case control study in the context of the aspBIOmics consortium

Here, we assessed whether 36 single nucleotide polymorphisms (SNPs) within the TNFSF4 and MAPKAPK2 loci influence the risk of developing invasive aspergillosis (IA). We conducted a two-stage case control study including 911 high-risk patients diagnosed with hematological malignancies that were ascertained through the aspBIOmics consortium. The meta-analysis of the discovery and replication populations revealed that carriers of the TNFSF4rs7526628T/T genotype had a significantly increased risk of developing IA (p = 0.00022). We also found that carriers of the TNFSF4rs7526628T allele showed decreased serum levels of TNFSF14 protein (p = 0.0027), and that their macrophages had a decreased fungicidal activity (p = 0.048). In addition, we observed that each copy of the MAPKAPK2rs12137965G allele increased the risk of IA by 60% (p = 0.0017), whereas each copy of the MAPKAPK2rs17013271T allele was estimated to decrease the risk of developing the disease (p = 0.0029). Mechanistically, we found that carriers of the risk MAPKAPK2rs12137965G allele showed increased numbers of CD38+IgM-IgD- plasmablasts in blood (p = 0.00086), whereas those harboring two copies of the allele had decreased serum concentrations of thymic stromal lymphopoietin (p = 0.00097). Finally, we also found that carriers of the protective MAPKAPK2rs17013271T allele had decreased numbers of CD27-IgM-IgD- B cells (p = 0.00087) and significantly lower numbers of CD14+ and CD14+CD16- cells (p = 0.00018 and 0.00023). Altogether, these results suggest a role of the TNFSF4 and MAPKAPK2 genes in determining IA risk.This study was supported by grants PI20/01845, PI12/02688, and ISCIII-FEDER PI17/02276 from Fondo de Investigaciones Sanitarias (Madrid, Spain), PIM2010EPA-00756 from the ERA-NET PathoGenoMics (0315900A), the Collaborative Research Center/Transregio 124 FungiNet, the Fundacao para a Ciencia e Tecnologia (FCT) (PTDC/SAU-SER/29635/2017, PTDC/MED-GEN/28778/2017, CEECIND/03628/2017, and CEECIND/04058/2018), the European Union's Horizon 2020 research and innovation programme under grant agreement no. 847507, and the "la Caixa" Foundation (ID 100010434) and FCT under the agreement LCF/PR/HP17/52190003)

Effectiveness of rotavirus vaccination in Spain

With the aim of determining rotavirus vaccine effectiveness (RVVE) in Spain, from Oct-2008/Jun-2009, 467 consecutive children below 2 years old with acute gastroenteritis (AGE) were recruited using a pediatric research network (ReGALIP-www.regalip.org) that includes primary, emergency and hospital care settings. Of 467 enrolled children, 32.3% were rotavirus positive and 35.0% had received at least one dose of any rotavirus vaccine. RRVE to prevent any episode of rotavirus AGE was 91.5% (95% CI: 83.7%-95.6%). RVVE to prevent hospitalization by rotavirus AGE was 95.6% (85.6-98.6%). No differences in RVVE were found regarding the vaccine used. Rotavirus vaccines have showed an outstanding effectiveness in Spain

Assessing the Psychedelic "After-Glow" in Ayahuasca Users : Post-Acute Neurometabolic and Functional Connectivity Changes Are Associated with Enhanced Mindfulness Capacities

Ayahuasca is a plant tea containing the psychedelic 5-HT agonist N,N -dimethyltryptamine and harmala monoamine-oxidase inhibitors. Acute administration leads to neurophysiological modifications in brain regions of the default mode network, purportedly through a glutamatergic mechanism. Post-acutely, ayahuasca potentiates mindfulness capacities in volunteers and induces rapid and sustained antidepressant effects in treatment-resistant patients. However, the mechanisms underlying these fast and maintained effects are poorly understood. Here, we investigated in an open-label uncontrolled study in 16 healthy volunteers ayahuasca-induced post-acute neurometabolic and connectivity modifications and their association with mindfulness measures. Using 1 H-magnetic resonance spectroscopy and functional connectivity, we compared baseline and post-acute neurometabolites and seed-to-voxel connectivity in the posterior and anterior cingulate cortex after a single ayahuasca dose. Magnetic resonance spectroscopy showed post-acute reductions in glutamate+glutamine, creatine, and N-acetylaspartate+N-acetylaspartylglutamate in the posterior cingulate cortex. Connectivity was increased between the posterior cingulate cortex and the anterior cingulate cortex, and between the anterior cingulate cortex and limbic structures in the right medial temporal lobe. Glutamate+glutamine reductions correlated with increases in the "nonjudging" subscale of the Five Facets Mindfulness Questionnaire. Increased anterior cingulate cortex-medial temporal lobe connectivity correlated with increased scores on the self-compassion questionnaire. Post-acute neural changes predicted sustained elevations in nonjudging 2 months later. These results support the involvement of glutamate neurotransmission in the effects of psychedelics in humans. They further suggest that neurometabolic changes in the posterior cingulate cortex, a key region within the default mode network, and increased connectivity between the anterior cingulate cortex and medial temporal lobe structures involved in emotion and memory potentially underlie the post-acute psychological effects of ayahuasca