The Use of Bone Substitutes in the Treatment of Bone Defects – the Clinical View and History

Summary: Bone has the ability to regenerate and remodel itself. In the clinic circumstances appear when bone defects do not heal spontaneously. These situations frequently result from trauma, congenital abnormities, infection or tumor resection. Hence, filling of the resulting defect by bone transplantation is a common practise with an increasing value in the re-establishment of the musculoskeletal system to promote bone healing. Since decades, efforts have been put to improve the effectiveness of bone substitutes. Conventional approaches with the use of ivory, animal and also human bone were not satisfactory. Negative effects like allergic reactions, rejection reactions, inflammations and other problems occurred. These led to implant failure, non union and amputation, to only mention a few. The introduction of bone banks and the development of standards in bone transplantation brought up the false hope to find a final solution for the treatment of bone loss. Disease transmissions (HIV) by allografts caused critical discussions. Despite all efforts, transplantation of autogenous cancellous bone is still the “gold standard” to induce bone healing. However, autografts are only limited available and are accompanied with high morbidity and mortality during the harvest. The problems associated with autologous and allogenous bone grafts promoted the development of multiple organic and inorganic bone substitutes. Well established substitutes at the present are demineralised bone matrix (DBM), composites and calcium phosphates (hydroxyl apatite and tri-calcium phosphate). These osteoconductive substances have shown to improve new bone formation. Nevertheless, clinical application of these materials is merely successful in a good bony environment but does not induce large progress in critical bone defects.     

Tetrameric DABCO–Bromine Complex: A Novel Reagent for Regeneration of Carbonyl Compounds From Aldoximes and Ketoximes

An efficient and convenient conversion of aldoximes and ketoximes to the corresponding carbonyl compounds with tetrameric DABCO–bromine complex is reported.     

C60: A host lattice for the intercalation of oxygen?

The investigation of structural and electronic properties of the novel family of fullerenes depends on the existence of pure reference materials. Sublimation of the van-der Waals solids is a suitable purification method. Little attention has been paid to the question about the air stability of such sublimed samples in form of crystals or thin films. A combination of thermal desorption spectroscopy, thermal analysis and diffuse reflectance FT-IR spectroscopy is used to show the extent to which oxygen from dry air is intercalated into fullerenes and which detrimental reactivity occurs from attempts to thermally remove (nneal) air-exposed samples. The conclusion is that any fullerene sample exposed to air will be transformed in part into a polymeric non-fullerene carbon upon thermal treatment to above 400 K irrespective of its initial purity.Dedicated to Professor Dr. rer. nat. Dr. h.c. Hubertus Nickel on the occasion of his 65th birthday     

Promotion of lanthanum-supported cobalt-based catalysts for the Fischer–Tropsch reaction

This paper focuses on the effect of the La/Co ratio on the structure of alumina cobalt supported catalysts for Fischer–Tropsch synthesis. Catalysts are prepared by wetness impregnation of alumina followed by calcination in air. The catalysts contain 10 wt% of cobalt and between 0 and 20 wt% of La (0, 5, 10, 15, 20). The catalysts were activated by reduction in hydrogen at 673 K and the catalytic performance was evaluated in a fixed bed reactor at 20 bar and 493 K. A wide range of techniques (BET, XRD, TPR, and XPS) were used for catalyst characterization at each preparation step and showed strong impact of the La/Co ratio on the structure, reducibility of supported cobalt phases. It was shown that 10 wt% of lanthanum allows reducing cobalt aluminate and improving catalytic performances.     

Investigation of the mechanisms of the action of chemical modifiers for electrothermal atomic absorption spectrometry: what for and how?

Modern trends in the research of the action of chemical modifiers for electrothermal atomic absorption spectrometry (ETAAS) are discussed critically. The most prolific approach is that of investigation of processes occurring during the drying and pyrolysis stages with wide application of data from different fields of chemistry and physics.     

Proposition for the acylation mechanism of serine proteases: A one-step process?

This work proposes a very detailed ab initio study of the hypothesis for a one-step serine protease acylation process with one water molecule acting as the main catalyst reactant. For the 11 increasing complexity models considered, the minimum and transition state conformations for the reaction are determined by full geometry optimizations at the ab initio self-consistent field (SCF ) levels within several basis sets, from MINI-1 to 6-31G, and, for the smallest complexes, at the post-SCF MP2 level within the 6-31G** basis set. The related thermodynamical quantities are calculated for all the conformations. The influence of the oxyanion hole stabilizer and of the dyad His57-Asp102 is quantified and a very good agreement is obtained with point mutagenesis. The activation barrier is found in the range 15–18 kcal/mol. © 1996 John Wiley & Sons, Inc.     

Suitability of different containers for the sampling and storage of biogas and biomethane for the determination of the trace-level impurities – A review

The traceable and accurate measurement of biogas impurities is essential in order to robustly assess compliance with the specifications for biomethane being developed by CEN/TC408. An essential part of any procedure aiming to determinate the content of impurities is the sampling and the transfer of the sample to the laboratory. Key issues are the suitability of the sample container and minimising the losses of impurities during the sampling and analysis process. In this paper, we review the state-of-the-art in biogas sampling with the focus on trace impurities. Most of the vessel suitability studies reviewed focused on raw biogas. Many parameters need to be studied when assessing the suitability of vessels for sampling and storage, among them, permeation through the walls, leaks through the valves or physical leaks, sorption losses and adsorption effects to the vessel walls, chemical reactions and the expected initial concentration level. The majority of these studies looked at siloxanes, for which sampling bags, canisters, impingers and sorbents have been reported to be fit-for-purpose in most cases, albeit with some limitations. We conclude that the optimum method requires a combination of different vessels to cover the wide range of impurities commonly found in biogas, which have a wide range of boiling points, polarities, water solubilities, and reactivities. The effects from all the parts of the sampling line must be considered and precautions must be undertaken to minimize these effects. More practical suitability tests, preferably using traceable reference gas mixtures, are needed to understand the influence of the containers and the sampling line on sample properties and to reduce the uncertainty of the measurement.     

Lipidology and lipidomics--quo vadis? A new era for the physical chemistry of lipids

Our picture of lipid membranes has come a long way since Gorter and Grendel in 1925 formulated the lipid bilayer hypothesis. Most modern textbook models of membranes are based on the Singer-Nicolson model from 1972, although we have in recent years seen significant amendments to this model, not least fuelled by the finding of lipid membrane domains and the subsequent 'raft rush'. The science of lipids, lipidology, has now become an established discipline, acknowledging that lipids organize in space and time and display emergent physico-chemical properties that are beyond the chemical nature of the individual molecules and which collectively control membrane function. Recently, lipidomics has been followed as a new discipline in the omics-sequel, characterized by an explosion in detailed data for lipid profiles of tissues, cells, and subcellular components. The focus is now swinging toward enumerating individual lipid species, determining their identity, and quantitating their amount. Time is ripe to marry the two disciplines, both in order to take lipidomics beyond the stage of 'stamp collection' and in order to incorporate into the lipidology approach the new knowledge about the individual lipid species. As an important matchmaker for this marriage, the physical chemistry of lipids in lipid bilayers and membranes is entering a new era of renaissance.     

A Rapid and Convenient Procedure for the Permethylation of Polysaccharides

MethylationofpolysaccharideshasprovedinvaluablefortheelucidationofthetyPesoflinkagewhichoccurbetWeendifferentsugarresidues.UPtothepresent,thereisnoperfectmethylationmeth0df0rpermethylationofpolysaccharidesandtheirderivatives.Hakomori'sprocedure'isn0walmostuniversallyusedamongvariousmethylationmeth0ds.InHakomori'spr0cedure,CHsSOCHziY,generatedfr0mthereactionofdimethylsulPhoxideandsodinmhydride,isconsideredthemosteffectivebasicagent.Theagentplaysacriticalroleinsugaralkoxideformation.Howeve…     

Laponite–Gelatin Nanofibrous Microsphere Promoting Human Dental Follicle Stem Cells Attachment and Osteogenic Differentiation for Noninvasive Stem Cell Transplantation

Nanofibrous microspheres (NFM) are emerging as prominent next-generation biomimetic injectable scaffold system for stem cell delivery and different tissue regeneration where nanofibrous topography facilitates ECM-like stem cells niches. Addition of osteogenic bioactive nanosilicate platelets within NFM can provide osteoconductive cues to facilitate matrix mediated osteogenic differentiation of stem cells and enhance the efficiency of bone tissue regeneration. In this study, gelatin nanofibrous microspheres are prepared containing fluoride-doped laponite XL21 (LP) using the emulsion mediated thermal induce phase separation (TIPS) technique. Systematic studies are performed to understand the effect of physicochemical properties of biomimicking NFM alone and with different concentrations of LP on human dental follicle stem cells (hDFSCs), their cellular attachment, proliferation, and osteogenic differentiation. The study highlights the effect of LP nanosilicate with biomimicking nanofibrous injectable scaffold system aiding in enhancing stem cell differentiation under normal physiological conditions compared to NFM without LP. The laponite–NFM shows suitability as excellent injectable biomaterials system for stem cell attachment, proliferation and osteogenic differentiation for stem cell transplantation and bone tissue regeneration.     

A new methodology for the development of numerical methods for the numerical solution of the Schr?dinger equation

In the present paper we introduce a new methodology for the construction of numerical methods for the approximate solution of the one-dimensional Schr?dinger equation. The new methodology is based on the requirement of vanishing the phase-lag and its derivatives. The efficiency of the new methodology is proved via error analysis and numerical applications.     

Versatile Sugar Derivatives for the Synthesis of Potential Degradable Hydrophilic‐Hydrophobic Polyurethanes and Polyureas

Biodegradable polymers obtained from renewable natural sources are currently receiving increasing attention because they are an alternative to the traditional petroleum‐based plastics. In the present communication we describe the synthesis of the diol monomers 2,3,4‐tri‐O‐benzyl‐L‐arabinitol (ABnOH) and 2,3,4‐tri‐O‐benzylxylitol (XBnOH), and the diamino monomers 1,5‐diamino‐1,5‐dideoxy‐2,3,4‐tri‐O‐benzyl‐L‐arabinitol (ABnNH ₂ ) and 1,5‐diamino‐1,5‐dideoxy‐2,3,4‐tri‐O‐benzylxylitol (XBnNH ₂ ), which can be used in the preparation of new potentially biodegradable sugar‐based polymers. As an example, we describe the synthesis and characterization of a polyurethane [PU‐(ABnOH‐HMDI)] and a polyurea [PUR‐(ABnNH₂‐HMDI)] by poly addition reaction of ABnOH and ABnNH ₂ with 1,6‐hexamethylene diisocyanate.      

A New and Practical Procedure for the Preparation of the Glucohexatose Phytoalexin Elicitor

The phytoalexin elicitor β-(1→3)-branched β-( 1→6)-linked glucohexatose has been regio- and stereospecifically synthesized by coupling of the 3, 6-branched gluco-trisaccharide Schmidt reagent 10 with a mixture of multiol 3,6-branched gluco-trisaccharides 13 which consists of free 5,6‘-OH trisaccharide, free 5,2‘ ,6‘-OH trisaccharide, free 5,3‘ ,6‘-OH trisaccharide and so on. The compounds 10 and 13 were prepared from 1,2:5,6-di-O-isopropylidene-α-D-glucofuranose , 2, 3, 4, 6-tetra-O-ben-zoyi-a-D-glucopyranosyl trichioroacetimldate, and 2,3,4, 6-tetra-O-acetyl-α-D-glucopyranosyl trichloreacetimidate through regio- and stereoselective manners.     

Exact Radial Solution of the Non-relativistic Schr?dinger Equation for the Helium Atom with the Potential Harmonic Method

We proposed a simple potential harmonic(PH) scheme for calculating the non-relativistic radial correlation energies of atomic systems.The scheme was applied to the low-lying n1S(n=1,2) and n3S(n=2,3) states of the helium atom.The results exhibit a very stable convergence characterization in both the angular and radial directions with PH and generalized Laguerre functions(GLF) respectively,even though the method is non-variational one.The ninth significant figure of the non-relativistic radial energy(NRE) calculated for the ground state exactly agrees with that of the most accurate literature data from the modified configuration interaction method.The convergent NRE′s for the excited states 21S,23S and 33S with the similar accuracy were also obtained.     

A Simple and Efficient Procedure for the Preparation of O-aryl-O-ethyl-S-allyl Thiolophosphates

HubeiNaturalScienceFoundationforfinancialsupportChap-cyethy-S-allylthiOlwioSPhates(2a-j)havePOtenhalbiologicalachvihes.Inl983,Y.TamaruandZYoshidarePOrtedPallatuxn(o)catalyZedthiono-ffooloallylicrearr~mentOfcrallylphoSPhoro-andphoSPhonotheonaes,andaiSOreinvestigaedthennalrearrangementOfa-andy-methallyldiethyphOSPhorothionaesinrelallontotheregioselectivityObserVedinthePalladium(O)catalySisl'].InourPreviousStUdy,Hg(II)catalghcandthermalffoono-ffoolorearrangmentOfcrPrOPargylcreqlp…     

Chemo-enzymatic Synthesis and RAFT Polymerization of 6-O-Methacryloyl Mannose: A Suitable Glycopolymer for Binding to the Tetrameric Lectin Concanavalin A?

Summary: The chemo-enzymatic synthesis of 6-O-methacryloyl mannose (MaM) glycomonomer was successfully performed for the first time. Subsequent aqueous RAFT polymerization of the monomer yielded well-defined, linear poly(6-O-methacryloyl mannose) (PMaM) glycopolymers without the need for protecting and deprotecting group chemistry. As well as investigating the RAFT polymerization kinetics of this monomer using various initial monomer to chain transfer agent concentration ratios, the protein binding ability of the generated glycopolymer was tested using concanavalin A, a known mannose-residue binding lectin.     

Molecular Iodine as a Versatile Reagent for the Synthesis of Thiazoloquinoline—A Potential Antibacterial Agent

Abstract

A series of 3-(2-aminothiazol-4-yl)quinolin-2[1H]-ones 3 was prepared by neat reaction of quinolin-2[1H]-ones 1 with thioureas 2 in the presence of molecular iodine. The synthesized compounds were evaluated for their in vitro antimicrobial activities against Escherichia coli, Paedococcus sp., Lactobacillus, Yersinia enterocolitica, and Staphylococcus aureus. The green chemical approach for the synthesis of thiazoloquinolinone 3 was performed under neat conditions using molecular iodine as catalyst as well as reaction medium.

Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.

GRAPHICAL ABSTRACT      

Determination of the Amplification Factor for 2-Hydroxy-ethylperoxy Radicals in PERCA

Free radicals (HO?, HO2? and organic peroxy radicals RO2?) play a crucial role in atmospheric chemistry1,2. Accurate measurement of these species is important to understand the chemical processes in the atmosphere. Recently, a chemical amplify- cation tec…     

The reductionist paradox: are the laws of chemistry and physics sufficient for the discovery of new drugs?

Reductionism is alive and well in drug-discovery research. In that tradition, we continually improve experimental and computational methods for studying smaller and smaller aspects of biological systems. Although significant improvements continue to be made, are our efforts too narrowly focused? Suppose all error could be removed from these methods, would we then understand biological systems sufficiently well to design effective drugs? Currently, almost all drug research focuses on single targets. Should the process be expanded to include multiple targets? Recent efforts in this direction have lead to the emerging field of polypharmacology. This appears to be a move in the right direction, but how much polypharmacology is enough? As the complexity of the processes underlying polypharmacology increase will we be able to understand them and their inter-relationships? Is “new” mathematics unfamiliar in much of physics and chemistry research needed to accomplish this task? A number of these questions will be addressed in this paper, which focuses on issues and questions not answers to the drug-discovery conundrum.