Reconstituted States Research Articles

Development and Stability Study of Oseltamivir Reconstitutable Dry Suspension from Capsules

Oseltamivir phosphate (OSEL) is recommended for the prevention and treatment of influenza virus infection. In a hospital pharmacy, OSEL liquid extemporaneous preparation is generally compounded on a case-by-case basis from the capsules because it can be stored for a certain period. Therefore, the objective of the current research was to develop an oseltamivir reconstitutable dry suspension (ORDS), and to evaluate the stability of the ORDS. The dry-suspending vehicles were first developed and subjected to stability tests. The stable vehicle was selected to mix with the content of OSEL capsules and dry powder was termed ORDS. The stability of ORDS was then tested in both dried and reconstituted states. It was found that the dry vehicle using xanthan gum as a suspending agent (at 0.25% w/v of the reconstituted suspension) was the most stable formulation at 25°C and 45°C under 75% relative humidity (RH) for 28 days. Upon mixing with OSEL capsule contents, ORDS in the dried state showed no change in either physical or chemical properties after storing at room temperature for 7 days. For the reconstituted state, the ORDS showed no change in odor and pH after storing at 2°C to 8°C in a refrigerator, and 25°C and 45°C under 75%RH for 14 days. However, its color was slightly darker after storing at 45°C. The percentage remaining OSEL at the refrigerator temperatures was 98.13% ± 1.63%, at 25°C was 100.30% ± 0.71% and at 45°C was 97.54% ± 1.38%. In conclusion, ORDS may be a convenient alternative to extemporaneous preparations. Keywords: Oseltamivir capsule, Reconstitutable dry suspension, Extemporaneous, Physico-chemical stability, Influenza

Influence of shearing strain rate on the mechanical behaviour of three structured clays

This paper presents the stress–strain behaviour of three structured clays subjected to a number of stepwise changes in strain rate during shearing in a triaxial apparatus. Undrained compression tests were performed on clay specimens in both undisturbed and reconstituted states. As a result, it has been possible to identify the influence of structure on the rate-dependent response of the clays. Step changes in applied shearing strain rates for all tests resulted in predominately isotache-type behaviour within the range of strains from very small strains to large strains at failure. At very small strains, evidence of a limiting elastic modulus was established for both the stiff sedimentary and artificially cemented soil, which is consistent with published literature on other structured geomaterials. The stress–strain behaviour of all three materials was affected by both the degradation of structure with increasing strain and applied strain rate. The influence of structure on the time-dependent behaviour of the clays is discussed by comparing the response of undisturbed and reconstituted specimens and following normalisation by the equivalent pressure. Results indicate that the rate sensitivity evolves with increasing strains and reaches a maximum at strain levels associated with peak shearing resistance.

The effect of soil fabric on shrinkage behaviour and microstructure evolution of soft soils upon drying

Soft soils often contain important fractions of fines and organic matter which are characterized by high shrinkage potential. Investigating the shrinkage behaviour of soft soils is of primary importance to assess the durability of infrastructures exposed to climatic stresses. This paper investigates the influence of soil fabric on the shrinkage properties and the change in the microporosity structures over drying. Soil shrinkage tests were performed on Shenzhen soft clay (SZ soft clay) and fibrous peat. The effect of the initial fabric was investigated by comparing the samples at natural and reconstituted states, and the reconstituted peat samples with different fibre contents. To assist in the interpretation of the results, microstructural changes in the soil fabric were investigated by mercury intrusion porosimetry, scanning electron microscopy, and micro-CT scan. As the water gradually drains from the multilevel pores, different drying stages were identified. Pore refinements occurred during the drying process, accompanied by a progressive reduction in the peak pore entrance. Contrary to SZ soft clay, intensive shrinkage occurred in the last stage of fibrous peats, due to the collapse of interpores and cracks created during drying. The results showed that the magnitude of the intensive shrinkage increased with the fibre content. It suggests that fibres act as an unstable element in peat upon drying.

Geological and Geotechnical Characteristics of London Clay from the Isle of Sheppey

The paper describes a series of experimental testing on natural stiff London clay samples retrieved from the New Hook Farm in the Isle of Sheppey, UK. The experimental program includes determination of macroscopic and microscopic properties, chemical compositions, Atterberg limits, permeability, and compressibility parameters in both intact and reconstituted states. The paper integrates the earlier studies, the new findings, and the commercial investigation results with the aim to extend the current knowledge of the geological and geotechnical characteristics of this stiff clay from the east of the London basin. Some comparisons are also made with shallow depth London clay from Heathrow Terminal 5 site.

A conceptual constitutive model unifying slurried (saturated), compacted (unsaturated) and dry states

Reconstituted and compacted soils are commonly assumed to exhibit a fundamentally different behaviour due to different microstructure. However, inspection of pore size distribution of the same soil in compacted and reconstituted states suggests that the boundary between these two states is more blurred. This paper explores the continuity between the microstructure of reconstituted and compacted states of kaolin clay and formulates a conceptual constitutive model unifying these states. Clay samples were prepared by saturating the pore space with different fluids (water, acetone and air) and the effect of pore-fluid fraction on the micro- and macroscale response of the clay was investigated experimentally. A conceptual constitutive model for unsaturated clays for quasi-isotropic stress states was therefore formulated, which allows the modelling of various unsaturated hydro-mechanical paths based on constitutive parameters only derived from the compression behaviour of clay under dry and saturated conditions (testing on samples formed from dry powder and slurry, respectively).

Characterisation of state bounding surface at low effective stresses in clayey soils having different structures

Shallow stability analysis of natural or man-made soil slopes requires accurate characterisation of soil strength at low effective stresses (5–20 kPa), corresponding to mechanisms expected at 1–2 m depth. This study focused on the intertwining effects of soil structures at different scales and low stresses on the undrained strength of fine-grained soils, by testing two natural plastic clays and a clay–sand mixed soil at different states (intact, reconstituted and compacted) in a series of constant-volume direct shear and hollow cylinder simple shear tests. The non-linearity of the Hvorslev bounding surface was expressed well by a power law function. The normalised strength and the degree of its non-linearity of the clays at intact states were higher than at equivalent reconstituted states, probably owing to true inter-particle cohesion, as confirmed by the hollow cylinder apparatus tests. The compacted states led to significantly lower normalised strength than the reconstituted state in both clays, while they did not show significant difference in the clay–sand mixed soil. This observation was explained by meso-scale discontinuities by X-ray micro-computed tomography images. Compacted clays’ shear strength is associated with a meso-fabric very different from that in more homogeneous intact and reconstituted clays, and the conventional state normalisation based on the equivalent pressure does not capture it.

A study of the effects of weathering on soils derived from decomposed volcanic rocks

A comprehensive investigation was made of the effects of weathering on the nature and mechanics of volcanic saprolites from Hong Kong. Few such studies have been conducted in volcanic weathered soils and the application of a critical state type of framework that accounts for the effects of structure, as has been used here, is especially novel. The investigation examined the effects of spatial variations of the effects of weathering both vertically as the weathering degree alters, and horizontally through comparing data from different sites. In addition to index tests, SEM and XRD, an extensive series of oedometer, triaxial and multi-directional bender elements tests was carried out, comparing the behaviour of samples from different locations and depths in both intact and reconstituted states. This meant that the changes to the intrinsic (reconstituted) behaviour could be traced throughout different degrees of weathering along with the effects of changing structure on the mechanical behaviour of the intact soils. The intrinsic properties changed in a manner that was broadly consistent with the increasing of fines content and plasticity due to weathering. The effects of meso-structure were small to medium in compression, and in shearing they were generally even less evident, both at small strains and failure. The degrees of anisotropy of stiffness for both intact and reconstituted samples were mostly quite small.

Constitutive modelling of Otaniemi soft clay in both natural and reconstituted states

A rate-independent anisotropic elastoplastic constitutive model for natural soft clays is proposed, with emphasis on the effects of cementation or structure and fabric anisotropy. The characteristic non-linear normal compression line for structured soils is described by defining a variable compressibility as a function of plastic straining. No reference to the ‘intrinsic’ reconstituted state is required. The effect of plastic anisotropy is investigated from virgin constant stress ratio consolidation tests, which provide an accurate description of the equilibrium states of soil fabric. The change of fabric anisotropy is correlated with the change of inclination of the yield and plastic potential surfaces via a pair of improved rotational hardening laws. Experiments on Otaniemi clay samples in both natural and reconstituted states are simulated. Comparisons of numerical predictions with experimental data illustrate the feasibility and advantage of the proposed methodology to describe the mechanical behaviour of natural soft clays.

Cross-anisotropic deformation characteristics of natural sedimentary clays

The cross-anisotropic elasticity parameters were experimentally determined for six sedimentary clays of different ages and origins at both natural and reconstituted states by using high-precision triaxial apparatus. All the parameters and their dependency on the effective stress are satisfactorily described by a simple, conventional power-law model. The patterns of the inherent anisotropy exhibited close agreement between the natural and reconstituted states, suggesting that the development of natural microstructures due to ageing and diagenesis does not play a primary role in determining the anisotropy patterns in clays. Despite different degrees of stiffness anisotropy observed in the six clays, relatively well-defined correlations encompassing all the tested clays were found between certain stiffness parameters. While fully characterising the drained elasticity moduli is still a challenging laboratory task, these correlations will help estimate some of them based on more readily measurable undrained moduli. All the exponents in the stiffness model equations, representing the dependency of the moduli on effective stress states, were generally smaller for older natural clays, whereas they were broadly constant for reconstituted samples, indicating a cementation-like effect in older, aged clays. Poisson ratios, [Formula: see text], [Formula: see text] and [Formula: see text], were generally very small, with secant [Formula: see text] values becoming gradually larger at larger strains.

Liquid state DNP for water accessibility measurements on spin-labeled membrane proteins at physiological temperatures

We demonstrate the application of continuous wave dynamic nuclear polarization (DNP) at 0.35T for site-specific water accessibility studies on spin-labeled membrane proteins at concentrations in the 10–100μM range. The DNP effects at such low concentrations are weak and the experimentally achievable dynamic nuclear polarizations can be below the equilibrium polarization. This sensitivity problem is solved with an optimized home-built DNP probe head consisting of a dielectric microwave resonator and a saddle coil as close as possible to the sample. The performance of the probe head is demonstrated with both a modified pulsed EPR spectrometer and a dedicated CW EPR spectrometer equipped with a commercial NMR console. In comparison to a commercial pulsed ENDOR resonator, the home-built resonator has an FID detection sensitivity improvement of 2.15 and an electron spin excitation field improvement of 1.2. The reproducibility of the DNP results is tested on the water soluble maltose binding protein MalE of the ABC maltose importer, where we determine a net standard deviation of 9% in the primary DNP data in the concentration range between 10 and 100μM. DNP parameters are measured in a spin-labeled membrane protein, namely the vitamin B12 importer BtuCD in both detergent-solubilized and reconstituted states. The data obtained in different nucleotide states in the presence and absence of binding protein BtuF reveal the applicability of this technique to qualitatively extract water accessibility changes between different conformations by the ratio of primary DNP parameters ϵ. The ϵ-ratio unveils the physiologically relevant transmembrane communication in the transporter in terms of changes in water accessibility at the cytoplasmic gate of the protein induced by both BtuF binding at the periplasmic region of the transporter and ATP binding at the cytoplasmic nucleotide binding domains.

One-Dimensional Compression Behavior of a Soil with High Organic Matter Content

This paper addresses the one-dimensional compression behavior of a highly organic sapric soil in both its natural intact and reconstituted states, based on the results of constant rate of strain and incremental loading oedometer tests. The soil investigated contains 40–60% organic matter, comprised mainly of highly processed humic substances, and represents a “transitional” material between inorganic clays and peats. The inorganic portion is entirely finer than 0.075 mm , with over 60% in the clay fraction (<2 μm) , which XRD analyses indicate contains smectite and vermiculite. Testing of the soil in its intact state relies on high quality block samples and shows that the natural intact soil displays intermediate behavior between that typical of inorganic soft clays and that observed in peats, in terms of compressibility, hydraulic conductivity, and change in hydraulic conductivity with void ratio. As in the case of peats, the coefficient of consolidation is observed to decrease with increasing stress lev...

Statebuilding and Force: The Proper Role of Foreign Militaries

Recent military interventions, both peace operations authorized by the United Nations and actions by individual countries, have aimed at helping build new or reconstituted states. The legitimacy and success of these state-building interventions are often contested by local actors. Yet state-like structures are needed to ensure the rule of law and economic growth. This paper argues for a new approach: to direct the use of foreign force toward roles that helped states emerge as the most successful governance structures in historical Europe, by defending populations from outside attack, protecting them from banditry and violence, and enforcing predictable rules for commerce and civil life (while training local forces to assume these duties). This approach focuses attention on the practical need to prepare military forces for both traditional defence and police-like roles.

The influence of structure on the pre-failure behaviour of a natural clay

Results are presented of an extensive laboratory and field investigation of a Pleistocene stiff clay in its natural and reconstituted states, including constant rate of strain oedometer and triaxial tests over a wide stress range, scanning electron microscopy and chemical micro-analysis. The relationships between the structure of the clay, its geological history and its mechanical response are demonstrated. The structure of the clay is strongly influenced by bonding, apparently largely due to a film of amorphous calcite which developed in situ at the end of normal consolidation. The effects of structure on the stiffness of the clay are identified, with sensitivity as the parameter quantifying the mechanical effects of structure. A frictional flow rule is found generally to be applicable over a wide strain range, including yield, even when strong bonding is present, although its form is influenced by structure. A new normalization shows that the gross yield surface is isotropically hardening in terms of both volume and structural change. L'article présente les résultats de recherches approfondies, en laboratoire et sur le terrain, sur une argile raide du Pléistocène à l'état naturel et reconstituée, y compris des essais oedométriques et triaxiaux à taux de contrainte constant, sur un large éventail de contraintes, ainsi que les résultats de travaux de microscopie électronique à balayage et de micro-analyse chimique. Les auteurs montrent les rapports entre la structure de l'argile, son histoire géologique et sa réaction mécanique. La structure de l'argile est fortement influencée par l'adhérence, qui semble en grande partie due à une pellicule de calcite amorphe qui s'est formée sur place à la fin de la consolidation normale. Les auteurs identifient les effets de la structure sur la rigidité de l'argile, la sensibilité étant le paramètre qui quantifie les effets mécaniques de la structure. On constate qu'un écoulement de frottement s'applique généralement à un large éventail de contraintes, y compris à la limite d'élasticité, même quand l'adhérence est forte, bien que sa forme soit influencée par la structure. Une nouvelle normalisation montre que la surface brute d'écoulement subit un durcissement isotrope tant en volume qu'en changement structural.

Structure of striated microtubule-associated fibers of flagellar roots: Comparison of native and reconstituted states

Several fiber systems are associated with the flagella and basal bodies of eukaryotic cells. Apart from the contractile and Ca 2+-sensitive system-II fibers, these include the non-contractile system-I fibers that run parallel to flagellar root microtubules. Using electron microscopy and image reconstruction, we have investigated the structure of the system-I fibers of the flagellate green alga Spermatozopsis similis. The fibers were observed in three different states: (1) in situ, (2) after isolation of the intact fibers, (3) after disassembly and reconstitution of fibers in vitro from their 34 kDa subunit protein. The fibers are highly ordered; they show a constant repeat of 28 nm, they are polar, and they contain several transverse and longitudinal striations. A model is discussed showing the system-I fiber to be built from rod-like molecules with a staggered arrangement and identical polarities.

Proteolysis and orientation on reconstitution of the coated vesicle proton pump.

We recently proposed a structural model for the ATP-dependent proton pump from clathrin-coated vesicles (Arai, H., Terres, G., Pink, S., and Forgac, M. (1988) J. Biol. Chem. 263, 8796-8802). To test this model further, we have carried out additional structural analysis of the (H+)-ATPase in both the detergent-solubilized and reconstituted states in this and the following paper (Adachi, I., Puopolo, K., Marquez-Sterling, N., Arai, H., and Forgac, M. (1990) J. Biol. Chem. 265, 967-973). The orientation of the reconstituted proton pump was determined by analyzing the effect of detergent on ATP hydrolysis and by quantitating the extent of labeling of luminally oriented subunits using a membrane-impermeant reagent. Greater than 90% of the reconstituted (H+)-ATPase is oriented with the cytoplasmic surface facing outward. Treatment of the reconstituted (H+)-ATPase with trypsin results in rapid cleavage of the 100-, 73-, 58-, 38-, and 34-kDa subunits and slower cleavage of the 40- and 33-kDa subunits, consistent with our previous results indicating that all of these polypeptides have some portion of their mass exposed to the cytoplasmic surface. The 19- and 17-kDa subunits, by contrast, appear resistant to cleavage by trypsin in both the detergent-solubilized and reconstituted states, consistent with their being buried extensively in the hydrophobic phase of the bilayer. Treatment of the enzyme with trypsin under conditions in which the 100-, 73-, 58-, 38-, and 34-kDa subunits have been cleaved results in a species which is virtually inactive with respect to proton transport but retains 50% of the original ATPase activity, suggesting that proteolysis has resulted in uncoupling of these two activities. Cleavage of both the 73- and 58-kDa subunits by trypsin at a site 1-2 kDa from the amino terminus is inhibited in the presence of 2',3'-O-(2,4,6-trinitrophenyl)-ATP, consistent with the suggestion that both the 73- and 58-kDa subunits may be nucleotide binding proteins.

Interaction of anions and ATP with the coated vesicle proton pump

ATP-driven proton transport in intact clathrin-coated vesicles requires the presence of a permeant anion, such as Cl-, to provide charge compensation during the electrogenic movement of protons. Using the purified (H+)-ATPase from clathrin-coated vesicles in both the detergent-solubilized and reconstituted states, we have studied the direct effects of anions on the activity of this enzyme. Both proton transport and ATP hydrolysis by the purified enzyme are independent of the presence of Cl-. In addition, proton transport does not occur even at high Cl- concentrations unless K+ and valinomycin are present to dissipate the membrane potential generated. These results indicate that the anion channel which provides for Cl- flux in intact coated vesicles is not a component of the purified (H+)-ATPase. Inhibition of ATPase activity is observed in the presence of I-, NO3-, or SO4(2-), with 50% inhibition occurring at 350 mM I-, 50 mM NO3-, or 40 mM SO4(2-). The presence of ATP lowers the concentration of I- required for 50% inhibition from 350 mM to 100 mM and increases the maximal inhibition observed in the presence of NO3- from 65% to 100%. Two separate mechanisms appear to be responsible for anion inhibition of the (H+)-ATPase. Thus, I- and high concentrations of NO3- (in the presence of ATP) cause inhibition by dissociation of the (H+)-ATPase complex, while SO4(2-) and NO3- (in the absence of ATP) cause inhibition without dissociation of the complex, suggesting the existence of an inhibitory anion binding site on the enzyme.(ABSTRACT TRUNCATED AT 250 WORDS)