Lattice constants and expansivities of gas hydrates from 10 K up to the stability limit.

The lattice constants of hydrogenated and deuterated CH4-, CO2-, Xe- (clathrate structure type I) and N2-hydrates (clathrate structure type II) from 10 K up to the stability limit were established in neutron- and synchrotron diffraction experiments and were used to derive the related thermal expansivities. The following results emerge from this analysis: (1) The differences of expansivities of structure type I and II hydrates are fairly small. (2) Despite the larger guest-size of CO2 as compared to methane, CO2-hydrate has the smaller lattice constants at low temperatures, which is ascribed to the larger attractive guest-host interaction of the CO2-water system. (3) The expansivity of CO2-hydrate is larger than for CH4-hydrate which leads to larger lattice constants for the former at temperatures above ∼150 K; this is likely due to the higher motional degrees of freedom of the CO2 guest molecules. (4) The cage occupancies of Xe- and CO2-hydrates affect significantly the lattice constants. (5) Similar to ice Ih, the deuterated compounds have generally slightly larger lattice constants which can be ascribed to the somewhat weaker H-bonding. (6) Compared to ice Ih, the high temperature expansivities are about 50% larger; in contrast to ice Ih and the empty hydrate, there is no negative thermal expansion at low temperature. (7) A comparison of the experimental results with lattice dynamical work, with models based on an Einstein oscillator model, and results from inelastic neutron scattering suggest that the contribution of the guest atoms' vibrational energy to thermal expansion is important, most prominently for CO2- and Xe-hydrates.

Structural characterization of eutectic aqueous NaCl solutions under variable temperature and pressure conditions.

The structure of amorphous NaCl solutions produced by fast quenching is studied as a function of pressure, up to 4 GPa, by combined neutron diffraction experiments and classical molecular dynamics simulations. Similarly to LiCl solutions the system amorphizes at ambient pressure in a dense phase structurally similar to the e-HDA phase in pure water. The measurement of the static structure factor as a function of pressure allowed us to validate a new polarizable force field developed by Tazi et al., 2012, never tested under non-ambient conditions. We infer from simulations that the hydration shells of Na(+) cations form well defined octahedra composed of both H2O molecules and Cl(-) anions at low pressure. These octahedra are gradually broken by the seventh neighbour moving into the shell of first neighbours yielding an irregular geometry. In contrast to LiCl solutions and pure water, the system does not show a polyamorphic transition under pressure. This confirms that the existence of polyamorphism relies on the tetrahedral structure of water molecules, which is broken here.

Elucidating Individual Magnetic Contributions in Bi-Magnetic Fe3 O4 /Mn3 O4 Core/Shell Nanoparticles by Polarized Powder Neutron Diffraction.

Heterogeneous bi-magnetic nanostructured systems have had a sustained interest during the last decades owing to their unique magnetic properties and the wide range of derived potential applications. However, elucidating the details of their magnetic properties can be rather complex. Here, a comprehensive study of Fe3 O4 /Mn3 O4 core/shell nanoparticles using polarized neutron powder diffraction, which allows disentangling the magnetic contributions of each of the components, is presented. The results show that while at low fields the Fe3 O4 and Mn3 O4 magnetic moments averaged over the unit cell are antiferromagnetically coupled, at high fields, they orient parallel to each other. This magnetic reorientation of the Mn3 O4 shell moments is associated with a gradual evolution with the applied field of the local magnetic susceptibility from anisotropic to isotropic. Additionally, the magnetic coherence length of the Fe3 O4 cores shows some unusual field dependence due to the competition between the antiferromagnetic interface interaction and the Zeeman energies. The results demonstrate the great potential of the quantitative analysis of polarized neutron powder diffraction for the study of complex multiphase magnetic materials.

F/OH ratio in a rare fluorine-poor blue topaz from Padre Paraíso (Minas Gerais, Brazil) to unravel topaz's ambient of formation.

Topaz [Al2SiO4(F,OH)2] is one of the main fluorine-bearing silicates occurring in environments where variably acidic (F)/aqueous (OH) fluids saturate the silicate system. In this work we fully characterized blue topaz from Padre Paraíso (Minas Gerais, Brazil) by means of in situ synchrotron X-Ray and neutron powder diffraction measurements (temperature range 298-1273 K) combined with EDS microanalyses. Understanding the role of OH/F substitution in topaz is important in order to determine the hydrophilicity and the exchange reactions of fluorine by hydroxyl groups, and ultimately to characterize the environmental redox conditions (H2O/F) required for mineral formation. The fluorine content estimated from neutron diffraction data is ~ 1.03 a.f.u (10.34 wt%), in agreement with the chemical data (on average 10.0 wt%). The XOH [OH/(OH + F)] (0.484) is close to the maximum XOH value (0.5), and represents the OH- richest topaz composition so far analysed in the Minas Gerais district. Topaz crystallinity and fluorine content sharply decrease at 1170 K, while mullite phase starts growing. On the basis of this behaviour, we suggest that this temperature may represent the potential initial topaz's crystallization temperature from supercritical fluids in a pegmatite system. The log(fH2O/fHF)fluid (1.27 (0.06)) is coherent with the fluorine activity calculated for hydrothermal fluids (pegmatitic stage) in equilibrium with the forming mineral (log(fH2O/fHF)fluid = 1.2-6.5) and clearly different from pure magmatic (granitic) residual melts [log(fH2O/fHF)fluid < 1]. The modelled H2O saturated fluids with the F content not exceeding 1 wt% may represent an anomalous water-dominant / fluorine-poor pegmatite lens of the Padre Paraíso Pegmatite Field.

Magnetic structure of the kagome mixed compound (Co(0.5)Ni(0.5))(3)V(2)O(8).

We report the magnetic structure of (Co(0.5)Ni(0.5))(3)V(2)O(8) (CNVO) deduced by single crystal neutron diffraction. This compound exhibits features which differ from that of its parent compounds, which are absolutely collinear along the a axis for Co(3)V(2)O(8) (CVO) or exhibit magnetic moments predominantly in the a-b plane with small components along c in the case of Ni(3)V(2)O(8) (NVO). The averaged magnetic moments of the statistically distributed Ni(2+) and Co(2+) ions in CNVO are oriented in the a-c plane and form loops of quasiferromagnetically coupled spins. These loops are connected along the a axis and separated along the c axis by cross-tie spins forming a quasiferromagnetic wave with the upper part of the respective neighbouring loops. The magnetic moments are sinusoidally modulated by the propagation vector k = (0.49,0,0) with an average amplitude of 1.59(1) µ(B) for a magnetic ion on a cross-tie site and 1.60(1) µ(B) for the spine site. In addition to neutron diffraction, specific heat and magnetization data, which confirm that the only magnetic phase transition above 1.8 K is the onset of antiferromagnetic order at T(N) = 7.4(1) K, are presented.

A Markov theoretic description of stacking-disordered aperiodic crystals including ice and opaline silica.

This article reviews the Markov theoretic description of one-dimensional aperiodic crystals, describing the stacking-faulted crystal polytype as a special case of an aperiodic crystal. Under this description the centrosymmetric unit cell underlying a topologically centrosymmetric crystal is generalized to a reversible Markov chain underlying a reversible aperiodic crystal. It is shown that for the close-packed structure almost all stackings are irreversible when the interaction reichweite s > 4. Moreover, the article presents an analytic expression of the scattering cross section of a large class of stacking-disordered aperiodic crystals, lacking translational symmetry of their layers, including ice and opaline silica (opal CT). The observed stackings and their underlying reichweite are then related to the physics of various nucleation and growth processes of disordered ice. The article discusses how the derived expressions of scattering cross sections could significantly improve implementations of Rietveld's refinement scheme and compares this Q-space approach with the pair-distribution function analysis of stacking-disordered materials.

The immunochemical approach to the characterization of membrane proteins. Human erythrocyte membrane proteins analysed as a model system.

1. Crossed immunoelectrophoresis was used for extensive characterization of individual proteins of human erythrocyte membranes solubilized in non-ionic detergent. 2. The precipitates were assigned to extrinsic or intrinsic proteins. 3. Four glycoproteins were identified by their lectin binding behaviour, whilst five proteins were affected by neuraminidase, indicating them to be sialoglycoproteins. 4. Enzymatic activity is retained in the solubilized system and the presence of acetylcholinesterase and an ATPase was demonstrated. The formation of phosphorylated membrane proteins on incubation with [32P]ATP was demonstrated by autoradiography on the immunoelectrophoresis plates. 5. Five proteins located on the outer cell surface were identified by antibody binding to intact cells. These same proteins were degraded by proteolytic enzymes in intact cells but only three of them were labelled by lactoperoxidase-catalysed 125I-iodination. 6. Analysis of erythrocyte membrane proteins using quantitive immunoelectrophoresis yields results concordant with those obtained by dodecyl sulfate-polyacrylamide gel electrophoresis.

Quantitative immunoelectrophoresis of proteins in human erythrocyte membranes. Analysis of protein bands obtained by sodium dodecyl sulfate-polyacrylamide gel electrophoresis.

1. We have defined conditions that permit quantitative immunoelectrophoresis in agarose gels of dodecyl sulfate-solubilized erythrocyte membrane proteins. 2. Using human serum albumin, transferrin, MN-glycoprotein (glycophorin) and crude spectrin as test proteins, we found that accurate analyses are possible if samples and gels are 1% in non-ionic detergent (Berol EMU-043) or Triton X-100) and if no more than 100 nmol free dodecyl sulfate is applied per sample. 3. Dodecyl sulfate treated membranes analyzed by crossed immunoelectrophoresis using rabbit antibodies against membrane material yielded optimal precipitation patterns in gels containing 1% of non-ionic detergent. 4. Crossed immunoelectrophoresis in the presence of 1% of Berol revealed precipitates when 10 protein bands defined and isolated by preparative dodecyl sulfate-polyacrylamide gel electrophoresis were run against anti-membrane antibodies. Seven of these bands showed more than one precipitation arc, indicating the presence of more than one antigenic component. 5. Crossed-line immunoelectrophoresis showed that dodecyl sulfate-polyacrylamide gel electrophoresis bands 1, 2 and 2.1 shared common antigenic components. The MN-glycoprotein was present in bands 3, 4A, 4B and 5, where antigenic components of the major intrinsic erythrocyte membrane protein, band 3, were also found. 6. After absorption of the anti-membrane antibody with intact erythrocytes, immunoelectrophoresis showed the disappearance of the MN-glycoprotein precipitates. An increase in the area below the precipitate corresponding to the major intrinsic protein (band 3) was also observed, indicating exposure of some antigens of this protein on the outer surface of intact cells. 7. After absorption of the antibody preparation with washed erythrocyte membranes, immunoprecipitates were not seen in any experiments, indicating that all antigenic determinants observed are exposed at one or both surfaces of the membrane. 8. Our analyses indicate that the peptide moieties of serum lipoproteins do not constitute a significant component of erythrocyte membranes.

A set of analytical electrophoresis experiments to predict the results of affinity chromatographic separations: fractionation of allergens from cow's hair and dander.

Analytical affinity electrophoresis experiments are described as analogues of column and batch affinity experiments. The are based on crossed immunoelectrophoresis with included affinity, here concanavalian A (con A) and con A-Sepharose. Reactions with serum proteins and allergens from cow's hair and dander are described, and a purification scheme for the latter is described.

The third complement factor (C3) and its in vivo cleavage products: interaction with lectins and precipitation with polyethylene glycol.

Five molecular forms of C3 expressing D but not C epitopes were identified following in vivo activation of the complement system. Examination of concanavalin A (Con-A) reactivity in crossed immunoelectrophoresis revealed that native C3, C3c and the beta mobile form 4 of C3d were completely precipitated by 100 micrograms Con A/cm2. The alpha-1 mobile form 1 of C3d did not interact with Con A, whereas the alpha-2 mobile forms 2 and 3 were retarded in electrophoretic migration by Con A. Native C3, C3c, and forms 4 and 5 of C3d were precipitated by 12% (w/v) polyethylene glycol (PEG). Form 1 of C3d was soluble in these PEG concentrations, whereas forms 2 and 3 were partially precipitated.

Mosaic lectin and enzyme staining patterns in rat skeletal muscle.

We compared the localizations of lectin binding and activity for myosin ATPase and succinic dehydrogenase in sections of the gracilis, soleus, and masseter muscles from 10- and 60-day-old rats. In the 60-day-old rats, incubation of the muscle sections with the lectins ConA, GS-II, HPA, and jacalin gave rise to a mosaic staining pattern, especially in the gracilis muscle, in which the same fibers were strongly stained for ConA, GS-II, and HPA, whereas the staining with jacalin in these fibers was weak, and vice versa. There was no correspondence in the staining patterns for the enzymes and the lectins. In the masseter muscle only GS-II gave rise to distinct differences in the staining intensity between muscle fibers. In 10-day-old rats all fibers in the muscles were moderately stained with ConA, HPA, and jacalin, whereas a chessboard staining pattern could be observed after incubation with GS-II. In an extract of hindleg muscle from 60-day-old rats there was strong affinity for ConA and HPA and weak affinity for GS-II and jacalin, as shown by dot-blotting. After electrophoresis and blotting to nitrocellulose membranes, three muscle protein bands with apparent molecular weights of 100,000, 90,000, and 43,000 showed affinity for ConA, HPA, and GS-II, whereas no bands were jacalin positive. The complex lectin staining pattern in skeletal muscle might be related to development, specialization, and function of the muscles.

Iscom immunization with synthetic peptides representing measles virus hemagglutinin.

Synthetic peptides representing the measles virus (MV) hemagglutinin (MVH) were incorporated into immunostimulating complexes (iscoms) and used for immunization of rabbits. Nine regions of MVH were selected on the basis of hydropathy and antigenicity profiles, by use of the known primary structure of MVH. Six linear and three branched types of peptides were synthesized and conjugated to palmitic acid before incorporation into the iscom structure. Five of the anti-peptide sera reacted by ELISA with the homologous peptide but did not react with MV in the native state, indicating that either the selected sites are not represented on the surface of MV, or they could be a conformational epitope. Human-anti MV and rabbit anti-MV did not react with the peptides.

The influence of alpha1-acid glycoprotein (orosomucoid) and its glycoforms on the function of human thyrocytes and CHO cells transfected with the human TSH receptor.

Local immunological reactions might influence the structure of alpha1-acid glycoprotein (AGP, orosomucoid) leading to a pathological condition in e.g. the thyroid. The aim of this study was to investigate whether the AGP molecule had a direct effect on thyroid cell function in vitro. The influence of AGP and its three glycoforms, TSH (1.0 U/l), serum samples and several sugars (methyl-mannose, methyl-glycoside, N-acetyl-D-galactose, N-acetyl-D-glycoside, neuramidase) were studied with respect to their influence on the function of the Chinese Hamster Ovary (CHO) cell line transfected with the human TSH receptor (hTSHr) and on human thyroid follicular epithelial cells (TFEC) in secondary cultures. We found that low concentrations of AGP (0.001-0.05 microg/l) stimulated while high concentrations of AGP (0.25-1.0 microg/l) inhibited cAMP accumulation in both cell systems (n=24, P<0.0002). In CHO cells (JP26) and TFEC glycoforms 1 (n=9), 2 (n=12) or 3 (n=11) significantly inhibited the TSH stimulated cAMP production, respectively, compared to controls (P<0.0001) and was partially reversed by mannose (P<0.0004). Control CHO cells (JP02) without the hTSHr showed no response. The specificity of the reaction was further confirmed by binding of biotinylated glycoforms and streptavidin conjugated FITC to both cell systems. This is the first report demonstrating that AGP and/or its glycoforms affects thyroid cell function in vitro and that it does so by influencing the second messenger cAMP probably by interacting directly with the TSH receptor.

Long-term pathologic changes of alpha1-acid glycoprotein (orosomucoid) glycoforms in autoimmune thyroid disease.

OBJECTIVE: We measured alpha1-acid-glycoprotein (AGP) in patients with autoimmune thyroid disease to study a possible relationship between microheterogeneity of the naturally occurring glycoforms of AGP and autoimmune thyroid disease. DESIGN, PATIENTS, MEASUREMENTS: In a group of 12 fasting thyrotoxic patients (11 females, mean age: 43 years) with newly diagnosed Graves' disease (subgroup 1), we measured serum concentrations of total AGP and its 3 glycoforms (micromol/l, crossed affinity immunoelectrophoresis with con A in the first dimension gel) as well as total thyroxine, total triiodothyronine, thyrotropine, thyroid peroxidase antibodies (anti-TPO), antibodies against the TSH receptor (TRAb, TRAK), at baseline and after 12 months of antithyroid drug therapy (ATD). For comparison, 4 subgroups of thyroid patients (patients with Graves' disease and thyroid associated ophthalmopathy (TAO) (subgroup 2, n = 10), radioiodine treated Graves' patients (subgroup 3, n = 7), Graves' patients without TAO (subgroup 4, n = 13), patients with Hashimoto's thyroiditis (subgroup 5, n = 8)) and 25 normal controls (17 females, mean age: 38 years) were studied. RESULTS: In subgroups of TRAb positive Graves patients' serum levels of glycoform 1, 2 or 3 increased significantly (p < 0.005) after 12 months of ATD as compared to both baseline of that person or normal controls. No significant changes were found in the TRAb negative Hashimoto subgroup. CONCLUSION: Patients with autoimmune Graves' disease changed their relationship to AGP, and thus a role of AGP and its 3 glycoforms is suggested in the pathogenesis of Graves' disease.

Bacterial binding to extracellular matrix proteins -- in vitro adhesion.

A binding assay was developed and used to study the binding of oral streptococcus to immobilized human fibronectin, laminin, vitronectin, fibrinogen, heparin, and collagen IV. The protein binding was dependent on the broth used for bacterial growth. The binding after growth in brain heart infusion broth, trypticase soy broth, Todd-Hewitt broth, and Dulbecco's modified Eagle's medium was examined. Most of the strains were able to bind to immobilized fibronectin and laminin, and to a minor extent vitronectin. Binding was not observed on immobilized fibrinogen, collagen IV, or heparin. Measured surface hydrophobicity correlated well with the bacterial binding strength to the proteins. Streptococcal incubation with putative inhibitors indicates multiple binding mechanisms of a lectin-like and protein nature, possibly involving protein receptors.

Lectin staining of renal cell tumours with special emphasis on oncocytomas.

There are conflicting results respecting the segmental tubular origin of renal oncocytomas, a type of tumour said to be highly differentiated and benign, though metastases have been described. The aim of this study was, by applying different lectins on renal cell carcinomas (n = 50) and oncocytomas (n = 12), to search for patterns which could indicate a specific segmental origin of oncocytomas and perhaps elucidate the differentiation of this tumour. The following lectins were applied: jacalin, peanut agglutinin (PNA), wheat germ agglutinin (WGA), phytohemagglutinin E (PHA-E), concanavalin A (Con A), and Dolichos biflorus agglutinin (DBA). The results show that oncocytomas are positive when jacalin, a Lectin that stains distal tubules and collecting tubules, is used, supporting the view that the tumour derives from distal or collecting tubules. The staining of the oncocytomas is generally polarized as in normal kidney tubules underlining that the tumour is highly differentiated. Two oncocytomas with aggressive behaviour showed areas with a diffuse pattern suggesting lower differentiation.

Lectins as probes for the assay of rhabdovirus infections in plants.

Thirteen different, biotinylated plant lectins were tested for their ability to recognize specifically the glycoproteins of the two different plant rhabdoviruses potato yellow dwarf virus and eggplant mottled dwarf virus. All viruses were propagated on the same plant host species, Nicotiana rustica L. The lectin-binding to the viral proteins was tested after electrophoretic separation and transfer to nitrocellulose membranes. Besides purified virus also partially pure virus preparations were used for the tests, in order to determine the specificity. The lectins had been selected for specificities to either one of the following monosaccharides: mannose, glucose, galactose, N-acetyl-D-galactosamine, N-acetyl-D-glucosamine and fucose. In the test panel of thirteen lectins, seven were found to react with the viral glycoproteins. Among these, four (LCA, VFA, PSA, Con A) belonged to the mannosyl- or glycosyl-specific group. However, these four lectins reacted also with other host proteins when partially pure virus preparations were used as samples. The other three lectins (GSA2b, STA, WGA) were specific for N-acetyl-D-glucosamine and detected almost exclusively the viral glycoproteins. Two of these lectins, STA and WGA, were extremely suitable for virus-specific assays, since they did not react with glycoproteins in healthy controls that were identical or comparable in their electrophoretic mobility with the rhabdovirus glycoproteins. No binding to viral glycoproteins was observed with galactose-, N-acetyl-galactosamine- and fucose-specific lectins. The assay for rhabdovirus glycoproteins in plants with the lectins was approximately 8-16 times less sensitive than with virus-specific antibodies.

Separation of monoclonal antibodies from cell-culture supernatants and ascites fluid using thiophilic agarose.

A one-step purification procedure will yield monoclonal antibodies from cell-culture supernatants and ascites fluids. The chromatographic adsorbent is thiophilic argose, i.e., beaded agarose gel coupled with ligands of thiophilic nature, often with a sulfone group and a sulfur atom. The chromatographic procedure is simply adsorption, wash, elution. The procedure is simple, efficient, and inexpensive.

The microheterogeneity of alpha 1-acid glycoprotein in inflammatory lung disease, cancer of the lung and normal health.

The concentration of alpha 1-acid glycoprotein (AGP, orosomucoid) was measured in sera from 19 patients with primary squamous cell carcinoma of the lung, 16 patients with an inflammatory lung disease and 17 persons with normal health. All sera were further subjected to crossed immuno-affinoelectrophoresis with addition of Con A in the first dimension and sugar in the second dimension. The distribution of AGP into four microheterogeneity forms, which were the result of this analysis, was estimated by measuring the area under the precipitation curve. The microheterogeneity patterns of AGP in the three groups were significantly different from each other (p less than 0.001). The total concentration of AGP in the two groups of patients was significantly different from the concentration in the healthy group (p less than 0.001).

The use of concanavalin A crossed immuno-affinoelectrophoresis to detect hormone-associated variations in alpha 1-acid glycoprotein.

alpha 1-Acid glycoprotein produces three peaks on crossed immuno-affinoelectrophoresis with concanavalin A in the first dimension, which is indicative of a degree of heterogeneity in the carbohydrate portion of this plasma glycoprotein. A different pattern, however, showing relatively less concanavalin A-binding material, is found in association with and after an increase in female sex hormone levels. Our observations strongly suggest a prolonged hormonal effect on the carbohydrate composition of alpha 1-acid glycoprotein, which may alter the metabolism or the function of the protein.