570 Biowissenschaften; Biologie
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Bioinspired stem cell-based hard tissue engineering includes numerous aspects: The synthesis and fabrication of appropriate scaffold materials, their analytical characterization, and guided osteogenesis using the sustained release of osteoinducing and/or osteoconducting drugs for mesenchymal stem cell differentiation, growth, and proliferation. Here, the effect of silicon- and silicate-containing materials on osteogenesis at the molecular level has been a particular focus within the last decade. This review summarizes recently published scientific results, including material developments and analysis, with a special focus on silicon hybrid bone composites. First, the sources, bioavailability, and functions of silicon on various tissues are discussed. The second focus is on the effects of calcium-silicate biomineralization and corresponding analytical methods in investigating osteogenesis and bone formation. Finally, recent developments in the manufacturing of Si-containing scaffolds are discussed, including in vitro and in vivo studies, as well as recently filed patents that focus on the influence of silicon on hard tissue formation.
Bei Thymian (Thymus vulgaris) handelt es sich um eine sehr varietätenreiche Art, die aufgrund ihres Gehaltes an therapeutisch wirksamen Inhaltsstoffen als Arzneipflanze monographiert ist. Insbesondere das ätherische Öl mit dem Hauptbestandteil Thymol (ca. 50%) hat eine hohe antioxidative Wirkung. Ziel ist es, dieses Potential als nachhaltig produzierte Additive zu nutzen. Hierfür eignen sich antioxidativ bzw. antimikrobiell wirksame sowie UV-absorbierende Substanzen, die das Produkt bei Zusatz vor oxidativem Stress, mikrobiellem Abbau und Qualitätsverlust schützen.
Hierzu werden zunächst sechs Varianten auf verschiedene Parameter analysiert, um die potenteste Variante auszuwählen. Auf diese Variante wird sich die weitere Forschung konzentrieren.
Daher wird das ätherische Öl durch azeotrope Destillation extrahiert und mittels GCMS analysiert. In Extrakten werden zudem das AP und Absorptionsverhalten bestimmt. Auch die chemische Zusammensetzung des Extrakts sowie die flüchtigen Stoffe des Thymians werden untersucht. Generell gibt es wenig qualitative, teilweise jedoch quantitative Unterschiede: Eine Variante weist u.a. einen deutlich höheren Thymolgehalt im Öl (ca. 65 %) und ein hohes hydrophiles AP auf. Somit ist eine vielversprechende Variante für die weitere Entwicklung und Optimierung bioaktiver Additive gefunden.
Miscanthus x giganteus Stem Versus Leaf-Derived Lignins Differing in Monolignol Ratio and Linkage
(2019)
As a renewable, Miscanthus offers numerous advantages such as high photosynthesis activity (as a C4 plant) and an exceptional CO2 fixation rate. These properties make Miscanthus very attractive for industrial exploitation, such as lignin generation. In this paper, we present a systematic study analyzing the correlation of the lignin structure with the Miscanthus genotype and plant portion (stem versus leaf). Specifically, the ratio of the three monolignols and corresponding building blocks as well as the linkages formed between the units have been studied. The lignin amount has been determined for M. x giganteus (Gig17, Gig34, Gig35), M. nagara (NagG10), M. sinensis (Sin2), and M. robustus (Rob4) harvested at different time points (September, December, and April). The influence of the Miscanthus genotype and plant component (leaf vs. stem) has been studied to develop corresponding structure-property relationships (i.e., correlations in molecular weight, polydispersity, and decomposition temperature). Lignin isolation was performed using non-catalyzed organosolv pulping and the structure analysis includes compositional analysis, Fourier transform infradred (FTIR), ultraviolet/visible (UV-Vis), hetero-nuclear single quantum correlation nuclear magnetic resonsnce (HSQC-NMR), thermogravimetric analysis (TGA), and pyrolysis gaschromatography/mass spectrometry (GC/MS). Structural differences were found for stem and leaf-derived lignins. Compared to beech wood lignins, Miscanthus lignins possess lower molecular weight and narrow polydispersities (<1.5 Miscanthus vs. >2.5 beech) corresponding to improved homogeneity. In addition to conventional univariate analysis of FTIR spectra, multivariate chemometrics revealed distinct differences for aromatic in-plane deformations of stem versus leaf-derived lignins. These results emphasize the potential of Miscanthus as a low-input resource and a Miscanthus-derived lignin as promising agricultural feedstock.
Physiology and behavior have historically been treated as separate subjects in the study of Drosophila. The latter is mentioned mainly in the context of neurobiology, while the former has been considered to take in studies of metabolism, cell biology and anatomy, among others. Of late, the line distinguishing physiology and behavior has become thinner, and this is exceptionally apparent in recent studies of nutrient signaling and of the regulation of feeding. This review represents a brief examination of the nexus between these intersecting fields of research in Drosophila. Other recently published reviews serve as complements to this one.
Reduced insulin/insulin-like growth factor (IGF) signaling may be a natural way for the reduction of dietary nutrients to extend lifespan. While evidence challenging this hypothesis is accumulating with Caenorhabditis elegans, for Drosophila melanogaster it is still thought that insulin/IGF and the mechanisms of dietary restriction (DR) might as yet function through overlapping mechanisms. Here, we aim to understand this potential overlap. We found that over-expression of dFOXO in head fat body extends lifespan and reduces steady-state mRNA abundance of insulin-like peptide-2 under conditions of high dietary yeast, but not when yeast is limiting. In contrast, conditions of DR that increase lifespan change only insulin-like peptide-5 (ilp5) mRNA abundance. Thus, reduction of ilp5 mRNA is associated with longevity extension by DR, while reduction of insulin-like peptide-2 is associated with the diet-dependent effects of FOXO over-expression upon lifespan. To assess whether reduction of ilp5 is required for DR to extend lifespan, we blocked its diet-dependent change with RNAi. Loss of the ilp5 dietary response did not diminish the capacity of DR to extend lifespan. Finally, we assessed the capacity of DR to extend lifespan in the absence of dFOXO, the insulin/IGF-responsive transcription factor. As with the knockdown of ilp5 diet responsiveness, DR was equally effective among genotypes with and without dFOXO. It is clear from many Drosophila studies that insulin/IGF mediates growth and metabolic responses to nutrition, but we now find no evidence that this endocrine system mediates the interaction between dietary yeast and longevity extension.
Die Rolle des Insulin-Signaltransduktionsweges in der Kontrolle der Entwicklung, der Physiologie und der Lebensdauer eines Organismus wurde in den vergangenen Jahren eingehend untersucht. Aufgrund seiner evolutionären Konservierung konnte durch Modellorganismen wie C. elegans, Drosophila und Mus musculus ein schneller Fortschritt bei der Entschlüsselung von Komponenten dieses Signalweges gemacht werden. In Drosophila wurden sieben verschiedene Homologe des Säuger-Insulins identifiziert. Drei der „Drosophila insulin-like peptides“ (dilps) werden in den medianen neuroendokrinen Zellen des Gehirns exprimiert. Diese Insulin-produzierenden Zellen (IPCs) senden neuronale Projektionen in Zellen der Corpora cardiaca. In diesen Zellen wird das Glucagonhomolog AKH (Adipokinetisches Hormon) produziert, zudem sind sie in der Lage Insulin zu speichern. Die beiden Zelltypen können als funktionelles Homolog der A- und B-Zellen des Säuger-Pankreas angesehen werden.
Bisher wurden die Studien in Drosophila an Mutanten des Insulin-Signaltransduktionsweges und an teilweise IPC-defizienten Fliegen durchgeführt. In beiden Fällen konnte der beobachtete Phänotyp von entwicklungsbedingten Defekten und der verminderten Insulin-Signalwirkung selbst ausgelöst worden sein. In dieser Arbeit wurden mit Hilfe des spät in der Entwicklung aktiven dilp3-Promotors und der Apoptose-induzierenden Faktoren RPR (reaper) und HID (Head involution defective) die IPCs zerstört. Ein larvaler Phänotyp wie bei den Mutanten des Insulin-Signaltransduktionsweges war nicht zu beobachten. So war es nun möglich, den Effekt einer verminderten Insulin-Signalwirkung in Adulten getrennt von entwicklungsabhängigen Effekten zu betrachten. Es zeigte sich, dass IPC-defiziente Weibchen Probleme haben, sich unterschiedlichen Nahrungsbedingungen anzupassen. Sie konnten Glycogen und Körperfett nicht so leicht abbauen. Weiterhin konnte gezeigt werden, dass bei Fütterung mit proteinreicher und kohlenhydratarmer Nahrung ihre Lebenserwartung gegenüber den Kontrollen erhöht war. Die Analyse dieser Fliegen mit Hilfe von cDNS-Microarrays führte zur Identifizierung des „target of brain insulin“ (tobi), einer α-Glucosidase, die im Darm und im Fettkörper von Adulten exprimiert wurde. TOBI ist evolutionär konserviert und es existiert ebenfalls ein menschliches Homolog. Das Transkript der α-Glucosidase wurde bei verminderter Insulin-Signalwirkung reprimiert, zudem wurde es abhängig von der Proteinkonzentration in der Nahrung reguliert. Durch die Zerstörung der AKH-produzierenden Zellen konnte tobi ebenfalls reprimiert werden. Dies zeigte, dass zusätzlich zu den IPCs auch die AKH-Zellen nötig waren, um das tobi-induzierende Signal weiterzuleiten. Diese Ergebnisse machen TOBI zu einem interessanten Zielgen des Insulinsignaltransduktionsweges, besonders seine mögliche Rolle im Alterungsprozess bedarf einer weiteren Untersuchung.
Small Molecules Enhance Scaffold-Based Bone Grafts via Purinergic Receptor Signaling in Stem Cells
(2018)
The need for bone grafts is high, due to age-related diseases, such as tumor resections, but also accidents, risky sports, and military conflicts. The gold standard for bone grafting is the use of autografts from the iliac crest, but the limited amount of accessible material demands new sources of bone replacement. The use of mesenchymal stem cells or their descendant cells, namely osteoblast, the bone-building cells and endothelial cells for angiogenesis, combined with artificial scaffolds, is a new approach. Mesenchymal stem cells (MSCs) can be obtained from the patient themselves, or from donors, as they barely cause an immune response in the recipient. However, MSCs never fully differentiate in vitro which might lead to unwanted effects in vivo. Interestingly, purinergic receptors can positively influence the differentiation of both osteoblasts and endothelial cells, using specific artificial ligands. An overview is given on purinergic receptor signaling in the most-needed cell types involved in bone metabolism-namely osteoblasts, osteoclasts, and endothelial cells. Furthermore, different types of scaffolds and their production methods will be elucidated. Finally, recent patents on scaffold materials, as wells as purinergic receptor-influencing molecules which might impact bone grafting, are discussed.
Antioxidant activity is an essential aspect of oxygen-sensitive merchandise and goods, such as food and corresponding packaging, cosmetics, and biomedicine. Technical lignin has not yet been applied as a natural antioxidant, mainly due to the complex heterogeneous structure and polydispersity of lignin. This report presents antioxidant capacity studies completed using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay. The influence of purification on lignin structure and activity was investigated. The purification procedure showed that double-fold selective extraction is the most efficient (confirmed by ultraviolet-visible (UV/Vis), Fourier transform infrared (FTIR), heteronuclear single quantum coherence (HSQC) and 31P nuclear magnetic resonance spectroscopy, size exclusion chromatography, and X-ray diffraction), resulting in fractions of very narrow polydispersity (3.2⁻1.6), up to four distinct absorption bands in UV/Vis spectroscopy. Due to differential scanning calorimetry measurements, the glass transition temperature increased from 123 to 185 °C for the purest fraction. Antioxidant capacity is discussed regarding the biomass source, pulping process, and degree of purification. Lignin obtained from industrial black liquor are compared with beech wood samples: antioxidant activity (DPPH inhibition) of kraft lignin fractions were 62⁻68%, whereas beech and spruce/pine-mixed lignin showed values of 42% and 64%, respectively. Total phenol content (TPC) of the isolated kraft lignin fractions varied between 26 and 35%, whereas beech and spruce/pine lignin were 33% and 34%, respectively. Storage decreased the TPC values but increased the DPPH inhibition.
Antioxidant activity is an essential feature required for oxygen-sensitive merchandise and goods, such as food and corresponding packaging as well as materials used in cosmetics and biomedicine. For example, vanillin, one of the most prominent antioxidants, is fabricated from lignin, the second most abundant natural polymer in the world. Antioxidant potential is primarily related to the termination of oxidation propagation reactions through hydrogen transfer. The application of technical lignin as a natural antioxidant has not yet been implemented in the industrial sector, mainly due to the complex heterogeneous structure and polydispersity of lignin. Thus, current research focuses on various isolation and purification strategies to improve the compatibility of lignin material with substrates and enhancing its stabilizing effect.
Amino acids perform multiple essential physiological roles in humans, and accordingly, their importance to health has been the subject of extensive attention. In this special issue of the Journal of Nutrition and Metabolism, we focus on the various inborn errors of amino acid metabolism, their diagnostic challenges, new treatment approaches, and recent advances in patient monitoring as well as clinical outcomes.
The human MPV17-related mitochondrial DNA depletion syndrome is an inherited autosomal recessive disease caused by mutations in the inner mitochondrial membrane protein MPV17. Although more than 30 MPV17 gene mutations were shown to be associated with mitochondrial DNA depletion syndrome, the function of MPV17 is still unknown. Mice deficient in Mpv17 show signs of premature aging. In the present study, we used electrophysiological measurements with recombinant MPV17 to reveal that this protein forms a non-selective channel with a pore diameter of 1.8 nm and located the channel's selectivity filter. The channel was weakly cation-selective and showed several subconductance states. Voltage-dependent gating of the channel was regulated by redox conditions and pH and was affected also in mutants mimicking a phosphorylated state. Likewise, the mitochondrial membrane potential (Δψm) and the cellular production of reactive oxygen species were higher in embryonic fibroblasts from Mpv17−/− mice. However, despite the elevated Δψm, the Mpv17-deficient mitochondria showed signs of accelerated fission. Together, these observations uncover the role of MPV17 as a Δψm-modulating channel that apparently contributes to mitochondrial homeostasis under different conditions.