Modelling thermal stability and activity of free and immobilized enzymes as a novel tool for enzyme reactor design

In this work, a novel method is proposed to establish the most suitable operational temperature for an enzyme reactor. The method was based on mathematical modelling of the thermal stability and activity of the enzyme and was developed using thermodynamic concepts and experimental data from free and immobilized inulinases (2,1-beta-D fructan frutanohydrolase, EC 3.2.1.7) from Kluyveromyces marxianus, which were used as examples. The model was, therefore, designed to predict the enzyme activity with respect to the temperature and time course of the enzymatic process, as well as its half-life, in a broad temperature range. The knowledge and information provided by the model could be used to design the operational temperature conditions, leading to higher enzyme activities, while preserving acceptable stability levels, which represent the link between higher productivity and lower process costs. For the inulinase used in this study, the optimum temperature conditions leading to higher enzyme activities were shown to be 63 degrees C and 57.5 degrees C for the free and immobilized inulinases, respectively. However, according to the novel method of approach used here, the more appropriate operating temperatures would be 52 degrees C for free and 42 degrees C for immobilized inulinases, showing that the working temperature is not necessarily the same as the maximum reaction rate temperature, but preferably a lower temperature where the enzyme is much more stable.     

A Real‐World Multicentre Retrospective Study of Paclitaxel‐Bevacizumab and Maintenance Therapy as First‐Line for HER2‐Negative Metastatic Breast Cancer

Bevacizumab in combination with taxanes in HER2‐negative metastatic breast cancer (MBC) patients has shown improved progression‐free survival (PFS), despite the lack of clear overall survival (OS) benefit. We performed a retrospective analysis to evaluate the impact of paclitaxel‐bevacizumab and of maintenance therapy with bevacizumab (BM) and endocrine therapy (ET) in the real‐world practice. We identified 314 HER2‐negative MBC patients treated in 12 cancer centers. Overall, the median PFS and OS were 14 and 40 months, respectively. Among the 254 patients potentially eligible for BM, 183 received BM after paclitaxel discontinuation until progression/toxicity. PFS and OS were improved in patients who had received BM in comparison with those potentially eligible but who did not receive BM (P< 0.0001 and P = 0.001, respectively). Results were confirmed when adjusting for propensity score. Among the 216 hormone‐receptor positive patients eligible for BM, a more favorable PFS and OS were observed when maintenance ET was administered (P < 0.0001). Multivariate analysis showed that PS, BM, number of disease sites and maintenance ET were related to PFS, while response and maintenance ET were related to OS. In hormone‐receptor positive patients, BM produced a significant PFS and a trend towards OS benefit only in absence of maintenance ET (P = 0.0007 and P = 0.06, respectively). In the triple‐negative subgroup, we observed a trend towards a better OS for patients who received BM (P = 0.06), without differences in PFS (P = 0.21). Our results confirmed the efficacy of first‐line paclitaxel‐bevacizumab in real‐world practice; both BM and maintenance ET significantly improved PFS and OS compared to no maintenance therapies. J. Cell. Physiol. 232: 1571–1578, 2017. © 2016 Wiley Periodicals, Inc.     

The Trypanosoma cruzi nucleic acid binding protein Tc38 presents changes in the intramitochondrial distribution during the cell cycle

Background  

Tc38 of Trypanosoma cruzi has been isolated as a single stranded DNA binding protein with high specifiCity for the poly [dT-dG] sequence. It is present only in Kinetoplastidae protozoa and its sequence lacks homology to known functional domains. Tc38 orthologues present in Trypanosoma brucei and Leishmania were proposed to participate in quite different cellular processes. To further understand the function of this protein in Trypanosoma cruzi, we examined its in vitro binding to biologically relevant [dT-dG] enriched sequences, its expression and subcellular localization during the cell cycle and through the parasite life stages.     

Expression of the Multiple Sclerosis-Associated MHC Class II Allele HLA-DRB1*1501 Is Regulated by Vitamin D

Multiple sclerosis (MS) is a complex trait in which allelic variation in the MHC class II region exerts the single strongest effect on genetic risk. Epidemiological data in MS provide strong evidence that environmental factors act at a population level to influence the unusual geographical distribution of this disease. Growing evidence implicates sunlight or vitamin D as a key environmental factor in aetiology. We hypothesised that this environmental candidate might interact with inherited factors and sought responsive regulatory elements in the MHC class II region. Sequence analysis localised a single MHC vitamin D response element (VDRE) to the promoter region of HLA-DRB1. Sequencing of this promoter in greater than 1,000 chromosomes from HLA-DRB1 homozygotes showed absolute conservation of this putative VDRE on HLA-DRB1*15 haplotypes. In contrast, there was striking variation among non–MS-associated haplotypes. Electrophoretic mobility shift assays showed specific recruitment of vitamin D receptor to the VDRE in the HLA-DRB1*15 promoter, confirmed by chromatin immunoprecipitation experiments using lymphoblastoid cells homozygous for HLA-DRB1*15. Transient transfection using a luciferase reporter assay showed a functional role for this VDRE. B cells transiently transfected with the HLA-DRB1*15 gene promoter showed increased expression on stimulation with 1,25-dihydroxyvitamin D3 (P = 0.002) that was lost both on deletion of the VDRE or with the homologous “VDRE” sequence found in non–MS-associated HLA-DRB1 haplotypes. Flow cytometric analysis showed a specific increase in the cell surface expression of HLA-DRB1 upon addition of vitamin D only in HLA-DRB1*15 bearing lymphoblastoid cells. This study further implicates vitamin D as a strong environmental candidate in MS by demonstrating direct functional interaction with the major locus determining genetic susceptibility. These findings support a connection between the main epidemiological and genetic features of this disease with major practical implications for studies of disease mechanism and prevention.     

DNA fingerprint analysis of a free-range koala population

Thirty-six koalas in a free-range Queensland population were fingerprinted using an M13 probe in combination withMspI digestion. The technique was found to be highly repeatable, with estimates of 0.1–1.6% within-gel error and 0.1–2.5% between-gel error. Of the 43 different-size fingerprint bands produced in the population, only 2 bands were common to all 36 koalas. Ten bands were quite rare, occurring at a frequency of 0.2 or less. All 36 koalas had unique DNA fingerprints (probability of 1.88×10^?7), which enabled them each to be uniquely identified. Despite this, there was still a high level of band sharing in the population (mean number of shared bands =0.749). This level is much higher than that reported for humans, birds, cats, dogs, and cattle but not as high as that reported previously for Victorian koalas. This lack of genetic variation may influence the ability of the population to respond to stress situations, such as lack of food, habitat destruction, and disease.     

Citrus fruits and inflammaging: a systematic review

Phytochemistry Reviews - Inflammaging is a low-grade, chronic, asymptomatic, controlled and systemic pro-inflammatory status that appears during the aging process and is linked to many age-related...     

Submarine Hydrothermal Vents of the Aeolian Islands: Relationship Between Microbial Communities and Thermal Fluids

The relationship between fluid geochemistry and microbial communities was investigated for shallow (&lt; 25 m) submarine hydrothermal vents in the Aeolian Islands (Southern Italy). Thermal waters, gases, and deposits of white filamentous material were collected from 11 sites. The geochemical analyses showed a magmatic component was present in all sampled fluids. The total microbial abundances, evaluated as direct counts of picoplanktonic cells (ranging from 0.2 to 2 mu m in diameter), were between 1.55 107 and 4.18 108 cells per liter. Picophytoplankton (total autofluorescent cells) ranged from 9.6 105 to 7.88 106 cells per liter. Yellow-orange autofluorescent prokaryotes belonging to the cyanobacteria were more abundant than red autofluorescent eukaryotic cells. Chemolithoautotrophic, sulfur-oxidizing, rod-shaped Bacteria were isolated from venting water samples and identified as Thiobacillus -like. Microscopic examination of the white mat deposits showed the presence of filamentous microorganisms.