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PubMed1986

Immunochemical and ultrastructural characterization of serum proteins associated with monosodium urate crystals (MSU) in synovial fluid cells from patients with gout.

Immunoelectron microscopic (IEM) analysis of the surface coats of intracellular and extracellular monosodium urate (MSU) crystals in synovial fluid (SF) in gouty arthritis was performed using the ferritin-bridge method. Cells from patients with acute gout were fixed in 1% glutaraldehyde containing 0.05% saponin to permeabilize membranes for access of immunochemicals to intracellular antigens. Intracellular MSU crystals were observed in phagosomes of greater than 75% of both polymorphonuclear (PMNs) and mononuclear cells. Coating of crystals with IgG was more prominent than with IgM or IgA. Other proteins such as C3, and fibrinogen were also found to a lesser extent. Albumin was not detected in appreciable amounts on MSU crystals. Extracellular crystals also showed IgG to be bound more prominently than other proteins. The various proteins, shown here for the first time to be clearly associated with intracellular crystals by EM, and other materials associated with MSU crystals may influence the phlogistic properties of these crystals.

Arthritis↗
PubMed2003

[High-resolution electron microscopy of carious dissolution of enamel nano-crystals].

OBJECTIVES: To investigate the carious dissolution mechanism of enamel apatite nano-crystals at lattice fringe level and the possible correlation between the carious dissolution and the appearance of central dark line (CDL) in enamel crystals. METHODS: The body of the lesion in incipient enamel caries was observed by high resolution transmission electron microscopy (HRTEM, JOEL-2010 operating at 200 kv), combined with selected-area argon-ion-beam thinning technique. RESULTS: In the body of the lesion, the preferential core dissolution was found in most of enamel nano-crystals, whereas the peripheral dissolution of individual crystal could be occasionally observed. The initial carious dissolution of individual enamel apatite crystal occurred as a number of small electron-lucent spots along the central dark line with blurry, bent or disconnected lattice fringes. These small electron-lucent spots fused with each other to form large electron-lucent areas. Finally the central perforation was frequently seen in the crystals. The CDL always appeared in the same place with central perforation in carious crystals, which could be seen to extend along the CDL. CONCLUSIONS: The initial carious dissolution is directly related to the lattice defects in the enamel nano-crystals. The preferential core dissolution can be partly ascribed to the CDL, which is presumed to be particularly susceptible area to caries.

Dental Caries↗
PubMed2006

[Influence of sun radiation on optical properties of liquid crystal display device].

Sunlight affects mainly the light stability and life of liquid crystal display device, which will lead to rapid aging of the device. By measuring the optical properties of liquid crystal display devices radiated with different time by spectrophotometer, the influences of long time sunlight radiation on the optical properties of the device were studied, and the changes of its optical properties were analyzed. The results indicate that structural and optical properties of liquid crystal slices of calculator LCD (B group) and telephone LCD (C group) are similar and the qualities are relatively good, while the aging problem of personal computer LCD (A group) liquid crystal slice is more serious than those of B and C groups, moreover, the qualities of liquid crystal slices in A group are worse. The structural and optical properties of liquid crystal display device will change accordingly after long time sunlight radiation. The surface of liquid crystal display device will become yellow and nigrescent, and the spectrum transmission properties will decline markedly, which is related to liquid crystal materials and manufacturing techniques.

English Abstract↗
PubMed1990

Crystallization of membrane proteins: bovine rhodopsin.

The conditions for crystallization of the integral membrane protein bovine rhodopsin were determined. Crystals form over a wide range of protein concentration (0.4-15 mg ml-1) and pH (5.5-7.5) in detergent solutions of octyl-polyoxyethylene (o-POE) that contain inorganic salts as precipitants. Crystallization occurs in the detergent-rich phase under conditions of phase separation. This corroborates the results of experiments on the phase behavior of the detergent solution and on the distribution of rhodopsin between the salt-rich and detergent-rich phases formed at high salt concentrations. Crystals were needle shaped, and the best crystals were obtained by vapour diffusion, at room temperature, of a 2.5 mg ml-1 protein solution in a 1.5% (v/v) o-POE solution containing 1.5 M ammonium sulphate (pH 7.0) against unbuffered 2.85 M ammonium sulphate. The crystals thus produced had dimensions of approximately 70 microns x 70 microns x 1000 microns. These crystals were too small to allow X-ray diffraction studies of rhodopsin structure, but electron microscopic studies of negatively stained thin crystals allowed the definition of the projection belonging to the two-sided plane group p21, and showed unit cell parameters alpha (50 A), b (72 A), and gamma (90 degrees).

Animals↗
PubMed1990

Single crystals of a chimeric T7/T3 RNA polymerase with T3 promoter specificity and a nonprocessive T7 RNAP mutant.

Two RNA polymerases homologous to bacteriophage T7 RNA polymerase, bacteriophage Sp6 and T3 RNA polymerases, were screened for crystallization under conditions identical or similar to those reported for the growth of large single crystals of T7 RNA polymerase (Sousa, R., Rose, J. P., Chung, Y. J., Lafer, E. M., and Wang, B.-C. (1989) Proteins 5, 266; Sousa, R., Lafer, E. M., and Wang, B.-C. (1990) J. Crystal Growth, in press; Sousa, R., and Lafer, E. M. (1990) Methods 1, in press). A number of mutant T7 RNAPs were also screened under these conditions as were three chimeric RNA polymerases consisting of T7 RNAP N-terminal and T3 RNAP C-terminal sequences. One chimeric polymerase and two mutant polymerases crystallized readily under T7 RNAP crystallization conditions. The chimeric polymerase crystallized in a space group different from T7 RNA polymerase: orthorombic with unit cell parameters a = 75 A, b = 98 A, c = 159 A; space group P2(1)2(1)2(1) and 4 molecules/unit cell. This chimeric enzyme exhibits T3 promoter specificity and will make it possible to investigate how structural differences between the T3 and T7 RNA polymerase promoter recognition domains determine their different promoter specificities. One of the mutant polymerases successfully crystallized was an enzyme which can carry out promoter recognition and abortive transcription but cannot carry out processive transcription. Its structure may provide information on the nature of the conformational changes undergone by T7 RNAP in the abortive-processive switch. Crystals of the second mutant T7 RNA polymerase were unsuitable for x-ray analysis.

Chimera↗
PubMedDate not supplied

Imaging faces of shadowed magnetite (Fe(3)O(4)) crystals from magnetotactic bacteria with energy-filtering transmission electron microscopy.

We used energy-filtering transmission electron microscopy to image magnetite crystals isolated from uncultured magnetotactic bacteria. These magnetite crystals were shadowed in high vacuum with platinum at 45 degrees. The shadowed crystals were observed in a Zeiss (Thornwood, NY) CEM902 transmission electron microscope. Imaging shadowed crystals with inelastically scattered electrons provided information of the decoration pattern of small platinum particles over crystal surfaces, and thus information on surface characteristics of crystals. Results were comparable to those obtained from scanning electron microscopy using a field emitter gun. Electron energy loss spectra of the crystals as well as of the supporting film were recorded to evaluate variations of image contrast with energy losses. Results indicated that the contrast is attenuated with inelastic imaging and that the effect of contrast tuning caused a contrast inversion at a given point between 100 and 150 eV. We believe this approach can be useful for studying multilayered materials by transmission electron microscopy.

Bacteria↗
PubMed1996

Purification, crystallization, and preliminary x-ray diffraction studies of tRNA-guanine transglycosylase from Zymomonas mobilis.

The tRNA modifying enzyme tRNA-gnanine transglycosylase (Tgt) catalyzes the exchange of guanine in the first position of the anticodon with the quenine precursor 7-aminomethyl-7-deazagnanine. Tgt from Zymomonas mobilis has been purified by crystallization and further recrystallized to obtain single crystals suitable for X-ray diffraction studies. Crystals were grown by vapor diffusion/gel crystallization methods using PEG 8,000 as precipitant. Macroseeding techniques were employed to produce large single crystals. The crystals of Tgt belong to the monoclinic space group C2 with cell constants a = 92.1 A, b = 65.1 A, c = 71.9 A, and beta = 97.5 degrees and contain one molecule per asymmetric unit. A complete diffraction data set from one native crystal has been obtained at 1.85 A resolution.

Chromatography, Ion Exchange↗
PubMed1996

Purification and crystallization of a complex between human interferon gamma receptor (extracellular domain) and human interferon gamma.

X-ray diffraction quality crystals have been obtained from a complex between interferon gamma and the extracellular domain of its high-affinity cell surface receptor. The crystals were obtained from interferon gamma/interferon gamma receptor complexes purified by size exclusion chromatography. Diffraction quality crystals required analyzing these complex samples by isoelectric focusing gels to select purified complex fractions devoid of unbound interferon gamma. These studies used interferon gamma receptor engineered with an eight amino acid N-terminal deletion to eliminate heterogeneity generated due to proteolytic cleavage. In addition, the receptor was expressed in an E. coli secretion cell line which eliminated the need to refold the protein. Hexagonal crystals were grown from 1.6 M ammonium phosphate solutions and belong to a spacegroup of P6(5)22 with unit cell dimensions a = 145.9 A and c = 180.3 A. These crystals diffract to at least 2.9 A resolution when exposed to synchrotron radiation. SDS PAGE analysis of the crystals demonstrated that both interferon gamma and the receptor were present. Analysis of the x-ray diffraction data revealed that the crystals contain complexes with a stoichiometry of 2:1 receptor: ligand within the crystallographic asymmetric unit and consist of approximately 55% solvent.

Chromatography, Gel↗
PubMed1996

Crystallization of biological macromolecules from flash frozen samples on the Russian Space Station Mir.

One hundred eighty-three flash frozen, liquid-liquid diffusion and batch method protein and virus crystallization samples were launched aboard the Space Shuttle Discovery on June 27 (STS-71) and transferred to the Russian Space Station Mir on July 1, 1995. They were returned to earth November 20, 1995 (STS-74). Subsequent examination showed that of the 19 types of proteins and viruses investigated, 17 were crystallized during the period on Mir. The experiment demonstrates the utility of this very simple and inexpensive approach for the crystallization of biological macromolecules in space over extended time periods. The distribution of crystals among the three types of containers used indicated small samples yielded results equal or better than larger samples and that long diffusion path lengths were clearly better. Distribution of crystals within the container tubes showed a striking gradient of quality and size that indicated long, narrow tubes yield superior crystals, as predicted from other work based on crystallization in capillaries.

Biotechnology↗
PubMed1996

Effect of crystallization on apatite-layer formation of bioactive glass 45S5.

The bioactive glass 45S5 was crystallized to 8-100 vol % of crystals by thermal treatments from 550-680 degrees C. The micro-structure of the glass-ceramics had a very uniform crystal size, ranging from 8 to 20 microns. Fourier-transform infrared (FTIR) spectroscopy was used to determine the rate of hydroxycarbonate apatite (HCA) formation that occurs on bioactive glass and glass-ceramic implants when exposed to simulated body fluid (SBF) solutions. Crystallization did not inhibit development of a crystalline HCA layer, but the onset time of crystallization increased from 10 h for the parent glass to 22 h for 100% crystallized glass-ceramic. The rate of surface reactions was slower when the percentage of crystallization was > or = 60%.

Apatites↗
PubMed1999

Crystallization of beta-estradiol in an acrylic transdermal drug delivery system.

Transdermal drug delivery systems are pharmaceutical products that can deliver controlled doses of drugs from polymeric patches applied on the human skin. The long-term stability of these patches is a critical issue relative to their performance in delivering drugs at a constant rate. Where a drug has been dissolved in the polymeric adhesive patch, crystallization has been reported in several systems. This study uses a variety of characterization tools to determine the physical and chemical nature of the precipitates formed in situ in estradiol patches. Optical microscopy revealed that crystals were formed in a single layer inside the adhesive matrix and that there were two distinctly different morphologies: needle-like crystals and aggregates around the needles. From IR measurements it was evident that estradiol probably was present in more than one crystal form in these patches. Raman microscopy showed that the needle-like crystals contain the adhesive component and the aggregates some modified crystal form of estradiol, indicating that in addition to the drug, the polymeric adhesive also crystallizes during storage.

Acrylic Resins↗
PubMed2000

Crystal polymer interaction with new injectable bone substitute; SEM and Hr TEM study.

A composite constituted of calcium phosphate (CaP) granules and a hydrophilic polymer as a carrier (hydroxy-propyl-methyl cellulose, HPMC) was developed to be an injectable bone substitute (IBS, CNRS patent). IBS is a composite and not an ionic cement. The composite obtained is ready to use and sterile. Chemical interactions between organic and inorganic components appeared during the association of the two. The interactions of the CaP and the polymer have been studied using scanning electron microscopy (SEM), electron microprobe (EDX), and high-resolution transmission electron microscopy (HrTEM) SEM revealed a degradation of the granules into smaller particles while EDX was unable to show significant changes in the Ca/P ratio during aging of the composite. With Hr TEM, however, we observed hydrolysis (process of dissolution and precipitation) from the surface to about 13 nm into the HA crystals and occasional dissolution with precipitation of beta-TCP crystals. In HA, the first zone of interaction consisted of a single layer of small globular crystals of 2 to 3 nm in diameter. Numerous lattice patterns in all three axes could be observed. Under the globular crystals zone, the inter-reticular distances of the single crystals appeared enlarged by 1.2% (from 0.817 to 0.827 nm). The enlargement seems to correspond to diffusion of HPO(4) into the crystal lattice. In beta-TCP crystals, dissolution was observed to be several nanometers deep, but globular surface precipitation rarely was observed. With time or after steam sterilization, no changes were observed. These data demonstrate the strong interactions of the hydrophylic polymer with calcium phosphate, but only in the first several nanometers of thickness.

Bone Substitutes↗
PubMed2000

Disorder and twinning in molecular crystals: impurity-induced effects in adipic acid.

The variation in physical properties of crystals grown in the presence of additives or impurities have previously been attributed to lattice disorder developed during crystallization. Adipic acid crystallized in the presence of a variety of stereochemically related impurities typifies such behavior with disorder manifest in variations of dissolution rates and enthalpies of solution and fusion. In this case the most extreme habit, produced by the presence of added monoalkanoic acids, is a rounded dumbbell that was suggested previously to be a twinned crystal. In this contribution such crystals are fully characterized both through their external morphology and by means of single crystal X-ray diffraction. These techniques show that these particles are not twinned but rather are disordered single crystals comprising a small number of slightly misaligned domains. The interaction between additive and substrate is modeled and new additives selected that induce the formation of true mechanical twins in adipic acid.

Adipates↗
PubMed2001

Dissolution of poorly crystalline apatite crystals by osteoclasts determined on artificial thin-film apatite.

Poorly crystalline apatite (PCA) crystals introduced into bone tissue should be stable for a definite period before they are dissolved as a result of a host response. In this report, the dissolution of PCA crystals by the action of osteoclasts was studied on artificial thin films. These consisted of PCA crystals having similar crystallographic properties to bone crystals which were developed for assaying the osteoclast activity in vitro. The dissolution of minerals by osteoclasts decreased along with the decreased amount of labile phosphate and hydrogen phosphate domains of apatite crystals, which were caused by the crystal maturation temperature. A profound effect on mineral dissolution by pH in the culture medium was also shown. Low acidity considerably increased mineral dissolution, whereas a slight alkalinity totally blocked mineral dissolution. There was little difference in the mineral dissolution behavior of osteoclasts near the physiologic pH. In addition, it was determined whether mineral dissolution by osteoclasts was dependent on the destruction of the organic matrix. Nocodazole was introduced to inhibit the secretion of hydrolytic enzymes, and acetazolamide was added to inhibit acid production by the osteoclasts. There was no significant change as a result of nocodazole addition on mineral dissolution or by the addition of acetazolamide on degradation of collagen. These results indicate that small changes in the physicochemical properties of apatite crystals can decrease resorption by osteoclasts, which can be highly activated at low pH. These results also suggest that mineral dissolution and organic degradation by osteoclasts are self-regulating.

Acetazolamide↗
PubMed2001

Influence of crystal shape on the tableting performance of L-lysine monohydrochloride dihydrate.

The purpose of this study is to understand the influence of crystal shape on the tableting performance of L-lysine monohydrochloride (LMH) dihydrate, using the method of data analysis developed by Joiris E et al. 1998. Pharm Res 15:1122-1130. Phase-pure crystals of LMH dihydrate, prism-shaped (S) and plate-shaped (T), were prepared by adjusting the composition of the crystallization solvent. At the same compaction pressure, T always gives stronger tablets than S, (i.e.; the tabletability of T is greater). The porosity of tablets from T crystals is always greater than that of S crystals when compressed at the same pressure, (i.e.; the compressibility of T is lower). The tensile strength of T tablets, at the same porosity, is greater than that of S tablets, (i.e.; the compactibility of T is greater). Therefore, the greater tabletability of T is a result of its better compactibility that overcomes the negative effects by its lower compressibility. The greater compactibility of T is related to favorable orientation of the slip planes in the tablet, corresponding to greater plasticity under load. The yield strengths of T and S crystals are essentially the same (20 MPa). Therefore, the crystal shape influences the tableting performance but does not, in principle, affect the yield strength of LMH dihydrate.

Compressive Strength↗
PubMed1998

The murine homolog of the interleukin-8 receptor CXCR-2 is essential for the occurrence of neutrophilic inflammation in the air pouch model of acute urate crystal-induced gouty synovitis.

OBJECTIVE: Acute neutrophil-dependent inflammation is central to acute gout. Urate crystals induce different classes of neutrophil chemotaxins, including certain chemokines (e.g., interleukin-8 [IL-8], growth-related oncogene alpha [GROalpha]) that share CXCR-2 as a receptor. This study was undertaken to assess the role of CXCR-2 ligands in a model of acute gout. METHODS: Urate crystals were injected into subcutaneous air pouches in mice that expressed or lacked the murine CXCR-2 homolog (mIL-8RH), and the development of neutrophilic inflammation was assessed. RESULTS: In normal mice, urate crystals induced a 10-fold increase (P < 0.01) in pouch fluid leukocytes (principally neutrophils) at 4 hours. Leukocytes adhered to the pouch lining, where crystals, the mIL-8RH ligand KC/GROalpha, and cells bearing mIL-8RH were abundant. In mIL-8RH(-/-) mice, urate crystals induced a proteinaceous leukocyte-poor exudate at 4 hours, despite crystal-induced activation of resident cells (documented by KC/GROalpha expression). CONCLUSION: Chemokines that bind the IL-8 receptor CXCR-2 are essential for the development of acute neutrophilic inflammation in response to urate crystals in the subcutaneous air pouch model.

Acute Disease↗
PubMed2003

Role of S100A8 and S100A9 in neutrophil recruitment in response to monosodium urate monohydrate crystals in the air-pouch model of acute gouty arthritis.

OBJECTIVE: To examine the role of chemokines, S100A8, and S100A9 in neutrophil accumulation induced by the causative agent of gout, monosodium urate monohydrate (MSU) crystals. METHODS: MSU crystal-induced neutrophil migration was studied in the murine air-pouch model. Release of chemokines, S100A8, S100A9, and S100A8/A9 in response to MSU crystals was quantified by enzyme-linked immunosorbent assays. Recruited cells were counted following acetic blue staining, and the subpopulations were characterized by Wright-Giemsa staining of cytospins. RESULTS: MSU crystals induced the accumulation of neutrophils following injection in the air pouch, which correlated with the release of the chemokines CXCL1, CXCL2, CCL2, and CCL3. However, none of these was found to play an important role in neutrophil migration induced by MSU crystals by passive immunization with antibodies directed against each chemokine. S100A8, S100A9, and S100A8/A9 were also found at high levels in the pouch exudates following injection of MSU crystals. In addition, injection of S100A8, S100A9, or S100A8/A9 led to the accumulation of neutrophils in the murine air pouch, demonstrating their proinflammatory activities in vivo. Passive immunization with anti-S100A8 and anti-S100A9 led to a total inhibition of the accumulation of neutrophils. Finally, S100A8/A9 was found at high concentrations in the synovial fluid of patients with gout. CONCLUSION: S100A8 and S100A8/A9 are essential to neutrophil migration induced by MSU crystals. These results suggest that they might be involved in the pathogenesis of gout.

Acute Disease↗
PubMed2004

Quantifying anisotropic solute transport in protein crystals using 3-D laser scanning confocal microscopy visualization.

The diffusion of a solute, fluorescein into lysozyme protein crystals has been studied by confocal laser scanning microscopy (CLSM). Confocal laser scanning microscopy makes it possible to non-invasively obtain high-resolution three-dimensional (3-D) images of spatial distribution of fluorescein in lysozyme crystals at various time steps. Confocal laser scanning microscopy gives the fluorescence intensity profiles across horizontal planes at several depths of the crystal representing the concentration profiles during diffusion into the crystal. These intensity profiles were fitted with an anisotropic model to determine the diffusivity tensor. Effective diffusion coefficients obtained range from 6.2 x 10(-15) to 120 x 10(-15) m2/s depending on the lysozyme crystal morphology. The diffusion process is found to be anisotropic, and the level of anisotropy depends on the crystal morphology. The packing of the protein molecules in the crystal seems to be the major factor that determines the anisotropy.

Biological Transport↗