Metformin Preserves β-Cell Compensation in Insulin Secretion and Mass Expansion in Prediabetic Nile Rats

Prediabetes is a high-risk condition for type 2 diabetes (T2D). Pancreatic β-cells adapt to impaired glucose regulation in prediabetes by increasing insulin secretion and β-cell mass expansion. In people with prediabetes, metformin has been shown to prevent prediabetes conversion to diabetes. However, emerging evidence indicates that metformin has negative effects on β-cell function and survival. Our previous study established the Nile rat (NR) as a model for prediabetes, recapitulating characteristics of human β-cell compensation in function and mass expansion. In this study, we investigated the action of metformin on β-cells in vivo and in vitro. A 7-week metformin treatment improved glucose tolerance by reducing hepatic glucose output and enhancing insulin secretion. Although high-dose metformin inhibited β-cell glucose-stimulated insulin secretion in vitro, stimulation of β-cell insulin secretion was preserved in metformin-treated NRs via an indirect mechanism. Moreover, β-cells in NRs receiving metformin exhibited increased endoplasmic reticulum (ER) chaperones and alleviated apoptotic unfold protein response (UPR) without changes in the expression of cell identity genes. Additionally, metformin did not suppress β-cell mass compensation or proliferation. Taken together, despite the conflicting role indicated by in vitro studies, administration of metformin does not exert a negative effect on β-cell function or cell mass and, instead, early metformin treatment may help protect β-cells from exhaustion and decompensation.     

Characterization of Urine Stem Cell-Derived Extracellular Vesicles Reveals B Cell Stimulating Cargo

Elucidation of the biological functions of extracellular vesicles (EVs) and their potential roles in physiological and pathological processes is an expanding field of research. In this study, we characterized USC–derived EVs and studied their capacity to modulate the human immune response in vitro. We found that the USC–derived EVs are a heterogeneous population, ranging in size from that of micro–vesicles (150 nm–1 μm) down to that of exosomes (60–150 nm). Regarding their immunomodulatory functions, we found that upon isolation, the EVs (60–150 nm) induced B cell proliferation and IgM antibody secretion. Analysis of the EV contents unexpectedly revealed the presence of BAFF, APRIL, IL–6, and CD40L, all known to play a central role in B cell stimulation, differentiation, and humoral immunity. In regard to their effect on T cell functions, they resembled the function of mesenchymal stem cell (MSC)–derived EVs previously described, suppressing T cell response to activation. The finding that USC–derived EVs transport a potent bioactive cargo opens the door to a novel therapeutic avenue for boosting B cell responses in immunodeficiency or cancer.     

Absorption of silicon from artesian aquifer water and its impact on bone health in postmenopausal women: a 12 week pilot study

Background  

Decreased bone mineral density and osteoporosis in postmenopausal women represents a growing source of physical limitations and financial concerns in our aging population. While appropriate medical treatments such as bisphosphonate drugs and hormone replacement therapy exist, they are associated with serious side effects such as osteonecrosis of the jaw or increased cardiovascular risk. In addition to calcium and vitamin D supplementation, previous studies have demonstrated a beneficial effect of dietary silicon on bone health. This study evaluated the absorption of silicon from bottled artesian aquifer water and its effect on markers of bone metabolism.     

Recycling of Aqueous Supernatants in Soybean Oleosome Isolation

Oleosome extractions from soybean flour typically generate significant quantities of aqueous sucrose- and sodium chloride-rich supernatant which could be recycled. To determine the feasibility of recycling the oleosome process aqueous supernatants, three extraction protocols were evaluated. The first extraction used the original extraction solution, 0.1 M fresh potassium acetate pH 4.6 containing 0.4 M sucrose and 0.5 M NaCl. The second protocol reused the aqueous supernatant obtained from the first extraction. The third protocol reused the aqueous supernatant obtained from the second protocol. Oleosome extraction yields were significantly higher in the first extraction with enzymes (Multifect^® Pectinase FE, Multifect^® GC, and Multifect^® CX B, 1% each, v/w) compared to the yield when the supernatant was reused with no additional enzymes (81.41 ± 2.24 vs. 73.09 ± 3.39%, respectively). Oil yields from oleosome fractions were not statistically different when extractions were made with 0 or 3% enzymes in the third protocol. Protein was the predominant constituent in the supernatant in addition to mineral and carbohydrate. Soybean storage protein profile from recycled supernatants obtained without adding enzyme were similar to a traditional soy protein water extract but with a decrease of intensity of the β-conglycinin bands. Addition of 3% enzymes in both recycling protocols resulted in the disappearance of the α′ and α subunits of the β-conglycinin due to a protease contaminant in Multifect^® Pectinase FE. Results from this work revealed essential information for a promising possibility of the future industrial application of this technology.     

Contribution to the textural characterisation of Filtrasorb 400 and other commercial activated carbons commonly used for water treatment

The textural characteristics of three commercial activated carbons, Filtrasorb 400 (F400), Industrial React High Affinity and Picabiol, commonly used in water treatment, are reinvestigated. Nitrogen physisorption isotherms are determined in the range P/P ₀ = [4 × 10⁻⁷–0.998] and processed using BET, α_S (Sing), Dubinin–Radushkevich and Density Functional Theory methods. In addition, fractal dimensions are determined by the Frenkel–Halsey–Hill procedure. Since F400 is often considered as a reference material in studies on the adsorption of solutes in aqueous solutions, a review of the textural characteristics of this carbon is carried out. The results obtained in this work using the different methods are consistent and a critical crossed comparison of these results allows discussing the limitations of the methods used. In particular, the impact of the P/P ₀ range considered on S _BET value is examined. In addition, the accuracy of the BET specific surface area is assessed in the light of information from recent literature.     

Isolation of a Pyrazine Alarm Pheromone Component from the Fire Ant, <Emphasis Type=Italic>Solenopsis invicta</Emphasis>

Alarm pheromones in social insects are an essential part of a complex of pheromone interactions that contribute to the maintenance of colony integrity and sociality. The alarm pheromones of ants were among the first examples of animal pheromones identified, primarily because of the large amount of chemical produced and the distinctive responses of ants to the pheromone. However, the alarm pheromone of the fire ant, Solenopsis invicta, eluded identification for over four decades. We identified 2-ethyl-3,6-dimethylpyrazine as an alarm pheromone component of S. invicta. Worker fire ants detect the pyrazine alarm pheromone at 30 pg/ml, which is comparable to alarm pheromone sensitivities reported for other ant species. The source of this alarm pheromone are the mandibular glands, which, in fire ants, are not well developed and contain only about 300 pg of the compound, much less than the microgram quantities of alarm pheromones reported for several other ant species. Female and male sexuals and workers produce the pyrazine, which suggests that it may be involved in fire ant mating flight initiation, as well as the typical worker alarm response. This is the first report of 2-ethyl-3,6-dimethylpyrazine from a Solenopsis species and the first example of this alkaloid functioning as an alarm pheromone.     

The Study of a 231 French Patient Cohort Significantly Extends the Mutational Spectrum of the Two Major Usher Genes MYO7A and USH2A

Usher syndrome is an autosomal recessive disorder characterized by congenital hearing loss combined with retinitis pigmentosa, and in some cases, vestibular areflexia. Three clinical subtypes are distinguished, and MYO7A and USH2A represent the two major causal genes involved in Usher type I, the most severe form, and type II, the most frequent form, respectively. Massively parallel sequencing was performed on a cohort of patients in the context of a molecular diagnosis to confirm clinical suspicion of Usher syndrome. We report here 231 pathogenic MYO7A and USH2A genotypes identified in 73 Usher type I and 158 Usher type II patients. Furthermore, we present the ACMG classification of the variants, which comprise all types. Among them, 68 have not been previously reported in the literature, including 12 missense and 16 splice variants. We also report a new deep intronic variant in USH2A. Despite the important number of molecular studies published on these two genes, we show that during the course of routine genetic diagnosis, undescribed variants continue to be identified at a high rate. This is particularly pertinent in the current era, where therapeutic strategies based on DNA or RNA technologies are being developed.     

PGRP-LB: An Inside View into the Mechanism of the Amidase Reaction

Peptidoglycan recognition proteins (PGRPs) are ubiquitous among animals and play pivotal functions in insect immunity. Non-catalytic PGRPs are involved in the activation of immune pathways by binding to the peptidoglycan (PGN), whereas amidase PGRPs are capable of cleaving the PGN into non-immunogenic compounds. Drosophila PGRP-LB belongs to the amidase PGRPs and downregulates the immune deficiency (IMD) pathway by cleaving meso-2,6-diaminopimelic (meso-DAP or DAP)-type PGN. While the recognition process is well analyzed for the non-catalytic PGRPs, little is known about the enzymatic mechanism for the amidase PGRPs, despite their essential function in immune homeostasis. Here, we analyzed the specific activity of different isoforms of Drosophila PGRP-LB towards various PGN substrates to understand their specificity and role in Drosophila immunity. We show that these isoforms have similar activity towards the different compounds. To analyze the mechanism of the amidase activity, we performed site directed mutagenesis and solved the X-ray structures of wild-type Drosophila PGRP-LB and its mutants, with one of these structures presenting a protein complexed with the tracheal cytotoxin (TCT), a muropeptide derived from the PGN. Only the Y78F mutation abolished the PGN cleavage while other mutations reduced the activity solely. Together, our findings suggest the dynamic role of the residue Y78 in the amidase mechanism by nucleophilic attack through a water molecule to the carbonyl group of the amide function destabilized by Zn²⁺.     

Endothelial Colony-Forming Cells Dysfunctions Are Associated with Arterial Hypertension in a Rat Model of Intrauterine Growth Restriction

Infants born after intrauterine growth restriction (IUGR) are at risk of developing arterial hypertension at adulthood. The endothelium plays a major role in the pathogenesis of hypertension. Endothelial colony-forming cells (ECFCs), critical circulating components of the endothelium, are involved in vasculo-and angiogenesis and in endothelium repair. We previously described impaired functionality of ECFCs in cord blood of low-birth-weight newborns. However, whether early ECFC alterations persist thereafter and could be associated with hypertension in individuals born after IUGR remains unknown. A rat model of IUGR was induced by a maternal low-protein diet during gestation versus a control (CTRL) diet. In six-month-old offspring, only IUGR males have increased systolic blood pressure (tail-cuff plethysmography) and microvascular rarefaction (immunofluorescence). ECFCs isolated from bone marrow of IUGR versus CTRL males displayed a decreased proportion of CD31+ versus CD146+ staining on CD45− cells, CD34 expression (flow cytometry, immunofluorescence), reduced proliferation (BrdU incorporation), and an impaired capacity to form capillary-like structures (Matrigel test), associated with an impaired angiogenic profile (immunofluorescence). These dysfunctions were associated with oxidative stress (increased superoxide anion levels (fluorescent dye), decreased superoxide dismutase protein expression, increased DNA damage (immunofluorescence), and stress-induced premature senescence (SIPS; increased beta-galactosidase activity, increased p16^INK4a, and decreased sirtuin-1 protein expression). This study demonstrated an impaired functionality of ECFCs at adulthood associated with arterial hypertension in individuals born after IUGR.     

Incorporation of organic liquids into geopolymer materials - A review of processing,properties and applications

Geopolymers, composed of an amorphous three-dimensional inorganic network and synthesized by the activation of a solid alumino-silicate precursor with an alkaline activating solution, have attracted increasing attention because of their environmental benefits and favorable characteristics. This review deals with the development of organic/inorganic composite materials made by adding organic liquids into inorganic geopolymer matrices. Firstly, the incorporation processing approaches are presented and are divided into three categories: (i) Direct incorporation, (ii) Pre-emulsification (iii) Solid impregnation. Their main advantages and drawbacks are discussed in relation to the aimed properties. Secondly, this review highlights that geopolymers are low-cost candidates allowing technologically significant applications, through the incorporation of various organic liquids. Aside from the well-studied immobilization of industrial waste streams commonly known as stabilization/solidification (S/S), the development of highly porous geopolymer foams and the design of reinforced organic/inorganic composite matrices are being notably investigated. This review aims at summarizing the main published results, and fostering further investigations into innovative uses of organic liquids incorporated into geopolymers for a wide range of applications.