Effect of Acid Hydrolysis and Ball Milling on Porous Corn Starch

Porous corn starch from glucoamylase hydrolysis of native corn starch was examined before and after cross-linking, acid hydrolysis and dry ball milling. Cross-linking does not significantly change the crystallinity, water absorption or gelatinisation properties but acid hydrolysis at 60°C increases, proportionately, crystallinity and water absorption capacity and decreases moisture adsorption at humidities less than 80%, in comparison to untreated porous corn starch. Highly crystalline porous starch has a fragile granule structure. Ball milling destroys crystallinity in both normal, porous, and cross-linked or partially hydrolyzed starches. Particle sizes of 1–2m are obtained by milling dry starches for 48 h. Water absorption for milled starches is more than 200% (weight water/weight starch d.b.). Viscosities of these products were significantly reduced at high temperatures. Products formed stable gels in 25–30% dispersions in cold water.     

Site-Directed Immobilization of an Engineered Bone Morphogenetic Protein 2 (BMP2) Variant to Collagen-Based Microspheres Induces Bone Formation In Vivo

For the treatment of large bone defects, the commonly used technique of autologous bone grafting presents several drawbacks and limitations. With the discovery of the bone-inducing capabilities of bone morphogenetic protein 2 (BMP2), several delivery techniques were developed and translated to clinical applications. Implantation of scaffolds containing adsorbed BMP2 showed promising results. However, off-label use of this protein-scaffold combination caused severe complications due to an uncontrolled release of the growth factor, which has to be applied in supraphysiological doses in order to induce bone formation. Here, we propose an alternative strategy that focuses on the covalent immobilization of an engineered BMP2 variant to biocompatible scaffolds. The new BMP2 variant harbors an artificial amino acid with a specific functional group, allowing a site-directed covalent scaffold functionalization. The introduced artificial amino acid does not alter BMP2′s bioactivity in vitro. When applied in vivo, the covalently coupled BMP2 variant induces the formation of bone tissue characterized by a structurally different morphology compared to that induced by the same scaffold containing ab-/adsorbed wild-type BMP2. Our results clearly show that this innovative technique comprises translational potential for the development of novel osteoinductive materials, improving safety for patients and reducing costs.     

Morphogen Signals Shaping the Gastric Glands in Health and Disease

The adult gastric mucosa is characterised by deep invaginations of the epithelium called glands. These tissue architectural elements are maintained with the contribution of morphogen signals. Morphogens are expressed in specific areas of the tissue, and their diffusion generates gradients in the microenvironment. Cells at different positions in the gland sense a specific combination of signals that instruct them to differentiate, proliferate, regenerate, or migrate. Differentiated cells perform specific functions involved in digestion, such as the production of protective mucus and the secretion of digestive enzymes or gastric acid. Biopsies from gastric precancerous conditions usually display tissue aberrations and change the shape of the glands. Alteration of the morphogen signalling microenvironment is likely to underlie those conditions. Furthermore, genes involved in morphogen signalling pathways are found to be frequently mutated in gastric cancer. We summarise the most recent findings regarding alterations of morphogen signalling during gastric carcinogenesis, and we highlight the new stem cell technologies that are improving our understanding of the regulation of human tissue shape.     

Infrarotspektroskopischer (IR) Nachweis von gelöstem Wasser in abgeschreckten Schlacken (Modellsysteme Na2O · P2O5 und Na2O · 2 B2O3)

Inf rarotspektroskopie von Wasser in Schlacken. Chemischer Bindungszustand von Wasser in Schlacken, Abhängigkeit der integralen Extinktion der OH-Banden vom Wasserdampfpartialdruck. Wasserstoff beim ESU-Verfahren.     

Heterogeneous catalysts with programmable topologies generated by reticulation of organocatalysts into metal-organic frameworks: The case of squaramide

A well-established strategy to synthesize heterogeneous,metal-organic framework(MOF)catalysts that exhibit nanoconfinement effects,and specific pores with highly-localized catalytic sites,is to use organic linkers containing organocatalytic centers.Here,we report that by combining this linker approach with reticular chemistry,and exploiting three-dimensioanl(3D)MOF-structural data from the Cambridge Structural Database,we have designed four heterogeneous MOF-based catalysts for standard organic transformations.These programmable MOFs are isoreticular versions of pcu IRMOF-16,feu UiO-68 and pillared-pcu SNU-8X,the three most common topologies of MOFs built from the organic linker p.p'-terphenyldicarboxylic acid(tpdc).To synthesize the four squaramide-based MOFs,we designed and synthesized a linker,4,4’-((3,4-dioxocyclobut-1-ene-1,2-diyl)bis(azanedyil))dibenzoic acid(Sq_tpdc),which is identical in directionality and length to tpdc but which contains organocatalytic squaramide centers.Squaramides were chosen because their immobilization into a framework enhances its reactivity and stability while avoiding any self-quenching phenomena.Therefore,the four MOFs share the same organocatalytic squaramide moiety,but confine it within distinct pore environments.We then evaluated these MOFs as heterogeneous H-bonding catalysts in organic transformations:a Friedel-Crafts alkylation and an epoxide ring-opening.Some of them exhibited good performance in both reactions but all showed distinct catalytic profiles that reflect their structural differences.     

Pediatric Brain Tumors: Signatures from the Intact Proteome

The present investigation aimed to explore the intact proteome of tissues of pediatric brain tumors of different WHO grades and localizations, including medulloblastoma, pilocytic astrocytoma, and glioblastoma, in comparison with the available data on ependymoma, to contribute to the understanding of the molecular mechanisms underlying the onset and progression of these pathologies. Tissues have been homogenized in acidic water–acetonitrile solutions containing proteases inhibitors and analyzed by LC–high resolution MS for proteomic characterization and label-free relative quantitation. Tandem MS spectra have been analyzed by either manual inspection or software elaboration, followed by experimental/theoretical MS fragmentation data comparison by bioinformatic tools. Statistically significant differences in protein/peptide levels between the different tumor histotypes have been evaluated by ANOVA test and Tukey’s post-hoc test, considering a p-value > 0.05 as significant. Together with intact protein and peptide chains, in the range of molecular mass of 1.3–22.8 kDa, several naturally occurring fragments from major proteins, peptides, and proteoforms have been also identified, some exhibiting proper biological activities. Protein and peptide sequencing allowed for the identification of different post-translational modifications, with acetylations, oxidations, citrullinations, deamidations, and C-terminal truncations being the most frequently characterized. C-terminal truncations, lacking from two to four amino acid residues, particularly characterizing the β-thymosin peptides and ubiquitin, showed a different modulation in the diverse tumors studied. With respect to the other tumors, medulloblastoma, the most frequent malignant brain tumor of the pediatric age, was characterized by higher levels of thymosin β4 and β10 peptides, the latter and its des-IS form particularly marking this histotype. The distribution pattern of the C-terminal truncated forms was also different in glioblastoma, particularly underlying gender differences, according to the definition of male and female glioblastoma as biologically distinct diseases. Glioblastoma was also distinguished for the peculiar identification of the truncated form of the α-hemoglobin chain, lacking the C-terminal arginine, and exhibiting oxygen-binding and vasoconstrictive properties different from the intact form. The proteomic characterization of the undigested proteome, following the top-down approach, was challenging to originally investigate the post-translational events that differently characterize pediatric brain tumors. This study provides a contribution to elucidate the molecular profiles of the solid tumors most frequently affecting the pediatric age, and which are characterized by different grades of aggressiveness and localization.     

Absorption coefficient of bulk and thin film Cu2O

The optical absorption coefficient of thin film and bulk Cu₂O at room temperature is obtained from an accurate analysis of their transmittance and reflectance spectra. These absorption spectra are modeled, together with the low temperature data reported in the literature, using an analytical expression to assess and quantify the role of the different absorption mechanisms. The results suggest that direct forbidden transitions and indirect transitions play an almost equally relevant role. A table of the optical constants of Cu₂O single crystal is given for reference.