scholarly journals Structural Biology of Calcium Phosphate Nanoclusters Sequestered by Phosphoproteins

Crystals ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 755 ◽  
Author(s):  
Samuel Lenton ◽  
Qian Wang ◽  
Tommy Nylander ◽  
Susana Teixeira ◽  
Carl Holt
Keyword(s):  
Calcium Phosphate ◽  
Structural Biology ◽  
Size Structure ◽  
Stability Diagram ◽  
Stable Region ◽  
Minimum Concentration ◽  
Tooth Remineralization ◽  
Physiological Conditions ◽  
Physico Chemical ◽  
The Stability

Biofluids that contain stable calcium phosphate nanoclusters sequestered by phosphopeptides make it possible for soft and hard tissues to co-exist in the same organism with relative ease. The stability diagram of a solution of nanocluster complexes shows how the minimum concentration of phosphopeptide needed for stability increases with pH. In the stable region, amorphous calcium phosphate cannot precipitate. Nevertheless, if the solution is brought into contact with hydroxyapatite, the crystalline phase will grow at the expense of the nanocluster complexes. The physico-chemical principles governing the formation, composition, size, structure, and stability of the complexes are described. Examples are given of complexes formed by casein, osteopontin, and recombinant phosphopeptides. Application of these principles and properties to blood serum, milk, urine, and resting saliva is described to show that under physiological conditions they are in the stable region of their stability diagram and so cannot cause soft tissue calcification. Stimulated saliva, however, is in the metastable region, consistent with its role in tooth remineralization. Destabilization of biofluids, with consequential ill-effects, can occur when there is a failure of homeostasis, such as an increase in pH without a balancing increase in the concentration of sequestering phosphopeptides.

Effect of Biologically-Relevant Molecules on the Physico-Chemical Properties of Amorphous Magnesium–Calcium Phosphate Nanoparticles

2021 ◽  
Vol 21 (5) ◽  
pp. 2872-2878
Author(s):  
Rita Gelli ◽  
Serena Salvestrini ◽  
Francesca Ridi
Keyword(s):  
Calcium Phosphate ◽  
Chemical Properties ◽  
Inorganic Particles ◽  
Biologically Relevant ◽  
Distal Small Intestine ◽  
Physico Chemical ◽  
Calcium Phosphate Nanoparticles ◽  
Biologically Relevant Molecules ◽  
The Stability

The recently-discovered endogenous formation of amorphous magnesium–calcium phosphate nanoparticles (AMCPs) in human distal small intestine occurs in a complex environment, which is rich in biologically-relevant molecules and macromolecules that can shape the properties and the stability of these inorganic particles. In this work, we selected as case studies four diverse molecules, which have different properties and are representative of intestinal luminal components, namely butyric acid, lactose, gluten and peptidoglycan. We prepared AMCPs in the presence of these four additives and we investigated their effect on the features of the particles in terms of morphology, porosity, chemical nature and incorporation/adsorption. The combined use of electron microscopy, infrared spectroscopy and thermal analysis showed that while the morphology and microstructure of the particles do not depend on the type of additive present during the synthesis, AMCPs are able to incorporate a significant amount of peptidoglycan, similarly to the process in which they are involved in vivo.

scholarly journals Macro- and Micro-Heterogeneity of Natural and Recombinant IgG Antibodies

Antibodies ◽  
2019 ◽  
Vol 8 (1) ◽  
pp. 18 ◽  
Author(s):  
Alain Beck ◽  
Hongcheng Liu
Keyword(s):  
Igg Antibodies ◽  
Pharmaceutical Development ◽  
Structural Modifications ◽  
Physiological Conditions ◽  
Safety Risks ◽  
Physico Chemical ◽  
Product Profile ◽  
Recombinant Mabs ◽  
The Stability ◽  
Quality Target Product Profile

Recombinant monoclonal antibodies (mAbs) intended for therapeutic usage are required to be thoroughly characterized, which has promoted an extensive effort towards the understanding of the structures and heterogeneity of this major class of molecules. Batch consistency and comparability are highly relevant to the successful pharmaceutical development of mAbs and related products. Small structural modifications that contribute to molecule variants (or proteoforms) differing in size, charge or hydrophobicity have been identified. These modifications may impact (or not) the stability, pharmacokinetics, and efficacy of mAbs. The presence of the same type of modifications as found in endogenous immunoglobulin G (IgG) can substantially lower the safety risks of mAbs. The knowledge of modifications is also critical to the ranking of critical quality attributes (CQAs) of the drug and define the Quality Target Product Profile (QTPP). This review provides a summary of the current understanding of post-translational and physico-chemical modifications identified in recombinant mAbs and endogenous IgGs at physiological conditions.

Stabilization of Inverted Coupled Pendula Using Parametric Excitation

1997 ◽  
Author(s):  
Reiko Osada ◽  
Chikara Sato
Keyword(s):  
Parametric Excitation ◽  
Inverted Pendulum ◽  
Mathieu Equation ◽  
Stability Diagram ◽  
Affirmative Answer ◽  
Stable Region ◽  
View Point ◽  
Limited Region ◽  
Resonant Systems ◽  
The Stability

Abstract Parametric stabilization of a single inverted pendulum has been extensively studied using the Mathieu equation and its corresponding stability diagram. The inverted single pendulum may be stabilized using parametric excitation at a specified frequency and amplitude given by a narrow stable region in the Mathieu diagram. Coupled pendula with parametric excitation or corresponding resonant systems have been studied from mathematical view point (Cesari, 1959; Gambill, 1955; Richards, 1983), from electrical view point (Sato, 1962a; Sato, 1962b; Sato, 1971; Sato, 1975) and from mechanical view point (Sato, 1995). Coupled pendula with parametric excitation have been studied within a limited region by some researchers, including the authors. A study of inverted coupled pendula with parametric excitation has not been performed as far as the authors know. Usually it is assumed that inverted coupled pendula are unstable in the absence of any other stabilizing mechanism such as feedback. One question is whether the inverted coupled pendula could be stabilized only by parametric excitation? The present paper gives an affirmative answer to this question in a limited and finite region. The stability is also examined using the differential equations and other methods.

scholarly journals Stability of Fe-oxide nanoparticles coated with natural organic matter under relevant environmental conditions

2014 ◽  
Vol 70 (12) ◽  
pp. 2040-2046 ◽  
Author(s):  
L. Chekli ◽  
S. Phuntsho ◽  
L. D. Tijing ◽  
J. L. Zhou ◽  
J.-H. Kim ◽  
...  
Keyword(s):  
Organic Matter ◽  
Natural Organic Matter ◽  
Environmental Conditions ◽  
Divalent Cations ◽  
Oxide Nanoparticles ◽  
Fe Oxide ◽  
Coated Nanoparticles ◽  
Aggregation Behaviour ◽  
Physico Chemical ◽  
The Stability

Manufactured nanoparticles (MNPs) are increasingly released into the environment and thus research on their fate and behaviour in complex environmental samples is urgently needed. The fate of MNPs in the aquatic environment will mainly depend on the physico-chemical characteristics of the medium. The presence and concentration of natural organic matter (NOM) will play a significant role on the stability of MNPs by either decreasing or exacerbating the aggregation phenomenon. In this study, we firstly investigated the effect of NOM concentration on the aggregation behaviour of manufactured Fe-oxide nanoparticles. Then, the stability of the coated nanoparticles was assessed under relevant environmental conditions. Flow field-flow fractionation, an emerging method which is gaining popularity in the field of nanotechnology, has been employed and results have been compared to another size-measurement technique to provide increased confidence in the outcomes. Results showed enhanced stability when the nanoparticles are coated with NOM, which was due to electrosteric stabilisation. However, the presence of divalent cations, even at low concentration (i.e. less than 1 mM) was found to induce aggregation of NOM-coated nanoparticles via bridging mechanisms between NOM and Ca2+.

scholarly journals Regulation of calcium phosphate formation by amelogenins under physiological conditions

2011 ◽  
Vol 119 ◽  
pp. 103-111 ◽  
Author(s):  
Seo-Young Kwak ◽  
Samantha Green ◽  
Felicitas B. Wiedemann-Bidlack ◽  
Elia Beniash ◽  
Yasuo Yamakoshi ◽  
...  
Keyword(s):  
Calcium Phosphate ◽  
Physiological Conditions

CHARGE STABILITY AND CONDUCTANCE ANALYSIS OF ANTHRACENE-BASED SINGLE ELECTRON TRANSISTOR

2013 ◽  
Vol 12 (06) ◽  
pp. 1350045 ◽  
Author(s):  
ANURAG SRIVASTAVA ◽  
BODDEPALLI SANTHIBHUSHAN ◽  
PANKAJ DOBWAL
Keyword(s):  
Coulomb Blockade ◽  
Density Functional ◽  
Stability Diagram ◽  
Single Electron ◽  
Single Electron Transistor ◽  
Functional Theory ◽  
Charge Stability ◽  
Anthracene Molecule ◽  
The Stability ◽  
Experimental Values

The present paper discusses the investigation of electronic properties of anthracene-based single electron transistor (SET) operating in coulomb blockade region using Density Functional Theory (DFT) based Atomistix toolkit-Virtual nanolab. The charging energies of anthracene molecule in isolated as well as electrostatic SET environments have been calculated for analyzing the stability of the molecule for different charge states. Study also includes the analysis of SET conductance dependence on source/drain and gate potentials in reference to the charge stability diagram. Our computed charging energies for anthracene in isolated environment are in good agreement with the experimental values and the proposed anthracene SET shows good switching properties in comparison to other acene series SETs.

Evaluation of Non-Vibrating Utility Burner/Furnace Systems for Resistance to Thermoacoustic Oscillations

2006 ◽  
Author(s):  
Frantisek L. Eisinger ◽  
Robert E. Sullivan
Keyword(s):  
Design Process ◽  
Axial Direction ◽  
Stability Diagram ◽  
Stable Range ◽  
Design Engineers ◽  
Secondary Role ◽  
The Stability ◽  
Thermoacoustic Oscillations

Six burner/furnace systems which operated successfully without vibration are evaluated for resistance to thermoacoustic oscillations. The evaluation is based on the Rijke and Sondhauss models representing the combined burner/furnace (cold/hot) thermoacoustic systems. Frequency differences between the lowest vulnerable furnace acoustic frequencies in the burner axial direction and those of the systems’ Rijke and Sondhauss frequencies are evaluated to check for resonances. Most importantly, the stability of the Rijke and Sondhauss models is checked against the published design stability diagram of Eisinger [1] and Eisinger and Sullivan [2]. It is shown that the resistance to thermoacoustic oscillations is adequately defined by the published design stability diagram to which the evaluated cases generally adhere. Once the system falls into the stable range, the frequency differences or resonances appear to play only a secondary role. It is concluded, however, that in conjunction with stability, the primary criterion, sufficient frequency separations shall also be maintained in the design process to preclude resonances. The paper provides sufficient details to aid the design engineers.

The effects of drivers’ aggressive characteristics on traffic stability from a new car-following model

2016 ◽  
Vol 30 (18) ◽  
pp. 1650243 ◽  
Author(s):  
Guanghan Peng ◽  
Li Qing
Keyword(s):  
Stability Analysis ◽  
Nonlinear Analysis ◽  
Traffic Flow ◽  
Linear Stability Analysis ◽  
Stable Condition ◽  
Mkdv Equation ◽  
Stable Region ◽  
Car Following ◽  
Car Following Model ◽  
The Stability

In this paper, a new car-following model is proposed by considering the drivers’ aggressive characteristics. The stable condition and the modified Korteweg-de Vries (mKdV) equation are obtained by the linear stability analysis and nonlinear analysis, which show that the drivers’ aggressive characteristics can improve the stability of traffic flow. Furthermore, the numerical results show that the drivers’ aggressive characteristics increase the stable region of traffic flow and can reproduce the evolution and propagation of small perturbation.

scholarly journals Criteria for Judging the Quality of a Publication on Physicochemical Stability of Ready to Use Injectable Drugs

2017 ◽  
Vol 2 (2) ◽  
Author(s):  
Jean-Daniel Hecq ◽  
Benoit Bihin ◽  
Jacques Jamart ◽  
Laurence Galanti
Keyword(s):  
Hospital Pharmacist ◽  
Full Description ◽  
Intravenous Route ◽  
Compatibility Study ◽  
Injectable Drugs ◽  
Physico Chemical ◽  
Physicochemical Stability ◽  
Testing And Measurement ◽  
The Stability

AbstractIn hospitals, a major part of the drugs is administered via the intravenous route. When one wants to evaluate or know the stability of a drug in solution, it is necessary to know several physico-chemical parameters. Several reference works are available to help the hospital pharmacist with this research. However, reading these different sources can make you discover conflicting data. It is therefore necessary at this time to obtain the publications with contradictory results and to read them again. Seven criteria have been identified for judging the quality of a publication on physicochemical stability: full description of equipment, methods and analytical conditions of molecules studied; complete description of the procedures used to validate the analytical method; full indication of time testing and measurement bases or control; documentation on the analytical reproducibility; adequate statistical analysis; appropriate conclusions; appropriate references. In conclusion, everything in a compatibility study is important.

scholarly journals Nanosuspensions – An Update on Recent Patents, Methods of Preparation, and Evaluation Parameters

2020 ◽  
Vol 14 ◽  
Author(s):  
Harpreet Kaur Khanuja ◽  
Rajendra Awasthi ◽  
Meenu Mehta ◽  
Saurabh Satija ◽  
Alaa AA Aljabali ◽  
...  
Keyword(s):  
Drug Loading ◽  
Pharmaceutical Research ◽  
Vital Role ◽  
Solid Matrix ◽  
Colloidal Systems ◽  
Passive Targeting ◽  
Physico Chemical ◽  
Extensive Information ◽  
The Stability ◽  
Preparation And Evaluation

Background: Nanosuspensions are colloidal systems consisting of pure drug and stabilizers, without matrix or lyophilized into a solid matrix. Nanosuspensions improve the solubility of the drug both in the aqueous and organic phases. Nanosuspensions are also known as brick dust molecules, as they increase the dissolution of a system and improve absorption. Methods: Extensive information related to nanosuspensions and its associated patents were collected using PubMed and Google Scholar. Results: Over the last decade nanosuspensions have attracted tremendous interest in pharmaceutical research. It provides unique features including, improved solubility, high drug loading capacity, and passive targeting. These particles are costeffective, simple, and have lesser side effects with minimal dose requirements. However, the stability of nanosuspensions still warrants attention. Conclusion: Nanosuspensions plays a vital role in handling the numerous drug entities with difficult physico-chemical characteristics such as solubility and can further aid with a range of routes that include nasal, transdermal, occular, parenteral, pulmonary etc. This review highlights the relevance of nanosuspensions in achieving safe, effective and targeted drug delivery.

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