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PubMed2002

Calculated photonic structures for infrared emittance control.

Using an available program package based on the transfer-matrix method, we calculated the photonic band structure for two different structures: a quasi-three-dimensional crystal of square air rods in a high-index matrix and an opal structure of high-index spheres in a matrix of low index, epsilon = 1.5. The high index used is representative of gallium arsenide in the thermal infrared range. The geometric parameters of the rod dimension, sphere radius, and lattice constants were chosen to give total reflectance for normal incidence, i.e., minimum thermal emittance, in either one of the two infrared atmospheric windows. For these four photonic crystals, the bulk reflectance spectra and the wavelength-averaged thermal emittance as a function of crystal thickness were calculated. The results reveal that potentially useful thermal signature suppression is obtained for crystals as thin as 20-50 microm, i.e., comparable with that of a paint layer.

Journal Article↗
PubMed1979

Study on incorporation of homologous serum albumin into the developing rabbit incisor.

The incorporation pattern of the rabbit albumin labelled with Lissamine Rhodamine B200 or 125I into the rabbit dentine and the enamel matrices was studied by fluorescence microscopy and/or autoradiography. The fluorescence of the fluorochrome-labelled albumin was observed in the dentine at 6 hours and 3 days. Autoradiographic silver grains were observed over the predentine at 1 hour after the injection. They were found over the dentine matrix adjacent to the predentine-dentine junction at 6 hours. The silver grain band was concentrated over the internal dentine matrix at 3 days. However, an appreciable amount of the fluorescence could not be seen in the enamel at any time after the injection. Also, no significant differences in the number of autoradiographic silver grains were found over the enamel matrix between the experimental groups and the background at any time after the injection. These results suggested that albumin was incorporated into the developing dentine matrix but not into the developing enamel matrix.

Ameloblasts↗
PubMedDate not supplied

[Electron-oscillatory spectra of pyrimidine bases of nucleic acids in argon matrices].

The studies on the oscillatory structure of adsorption spectra of pyrimidine bases of nucleic acids isolated in Ar matrix at 11 K are described. To clear up the importance of molecule isolation in the matrix, amorphous films of the materials studied were investigated experimentally at 11 and 77 K. The work was carried out using the low temperature optic attachment developed by the authors. The long wavelength band of cytosine and deuterocytosine in the matrix is shown to consist of two bands: 1) lambda max = 267 nm with oscillatory progressions of 500 and 400 cm-1, respectively, and 2) lambda max = 280 nm with progression approximately 800 cm-1. The first pi pi*-absorption band of 1-methylcytosine has a single oscillatory progression 470 cm-1. Thymine and uracil in Ar matrices form diffuse structural spectra of 630 and 660 cm-1, respectively. The oscillatory progressions are attributed to the oscillatory frequencies of the pyrimidine molecule ring oscillations in the excited state. The annealing of the matrix results for all the materials in smearing the oscillatory molecule structure up to its complete vanishing. In film samples the oscillatory structure is not seen at low temperatures.

DNA↗
PubMed1988

Use of immunoblotting to characterize the mitochondrial antigens recognized by anti-mitochondrial autoantibodies.

Sera with anti-mitochondrial autoantibodies detected by indirect immunofluorescence and/or enzyme-linked immunosorbent assay (ELISA) were examined by immunoblotting against pig heart mitochondria. Seven types of reactions were defined, according to the pattern of the labelled bands. Type I sera reacted with 12 bands located within four zones. The most intensively labelled bands were located at 70, 67, 58, 63 and 43 kDa. Other types gave decreasing band numbers. When beef heart mitochondria were used, sera belonging to each of the above types had a profile of labelled bands which sometimes differed from those obtained with pig heart mitochondria. When the chloroform extracted F1-ATPase from beef heart mitochondria was used to prepare the immunoblots, primary biliary cirrhosis (PBC) sera with anti-mitochondria antibodies reacted with all the bands although zone A bands were less labelled. Rat liver mitochondria gave seven bands with type I sera among which the 57 and 35 kDa bands were specific for rat liver mitochondria, as shown by absorption tests. Sera of PBC patients were also tested in immunoblotting against rat liver subcellular fractions including mitoplasts, submitochondrial particles, inner membrane, outer membrane, matrix proteins and inter-membrane proteins. Antigenic bands of A and B zones were localized in the inner membrane and/or in the matrix proteins and the 35 kDa band in inter-membrane proteins. The outer membrane gave no reaction. The most frequent anti-mitochondrial autoantibody types in PBC were type II, then I, whilst for chronic active hepatitis type III was the most common. Type V was only seen in a patient suffering from a typical PBC. Some sera from patients with syphilis, collagenous colitis or progressive systemic sclerosis labelled one or two bands distinct from those labelled by the PBC sera. Sera from patients with drug-induced hepatitis with endoplasmic reticulum antibodies and with systemic lupus erythematosus were generally found negative by immunoblotting.

Animals↗
PubMed2003

Identification of proteins separated by one-dimensional sodium dodecyl sulfate/polyacrylamide gel electrophoresis with matrix-assisted laser desorption/ionization ion trap mass spectrometry; comparison with matrix-assisted laser desorption/ionization time-of-flight mass fingerprinting.

Digests from ten gel bands containing low abundance proteins were analyzed by both matrix-assisted laser desorption/ionization ion trap (MALDI-IT) and matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry (MS) methods. MALDI-TOF techniques were able to identify only one protein from all 10 gel bands, while MALDI-IT identified eight proteins from the same 10 bands. The ability to perform MS/MS experiments with a MALDI-IT instrument leads to protein identifications based on both peptide molecular mass and sequence information, and is much less prone to errors and uncertainties introduced by peptide fingerprinting methodologies in which protein identification is based on peptide molecular masses alone.

Amino Acid Sequence↗
PubMed1990

The effect of a single dose of 1-hydroxyethylidene-1, 1-bisphosphonate (HEBP) on secretory ameloblasts and enamel formation in rat incisors.

The present experiment was undertaken in order to study how HEBP affects secretory ameloblasts and the mineralizing front of rat incisor enamel resulting in the formation of a hypomineralized incremental band. Rats were given a single subcutaneous injection of 10 mg/kg body weight of HEBP and sacrificed at intervals ranging from 1 hour to 9 days. The incisors were specially prepared for microradiography, scanning electron microscopy, and light and transmission electron microscopy. The microradiographical examination 9 days after injection revealed a distinct incremental band of hypomineralization from the amelo-dentinal junction to the outer enamel surface. The overall rod pattern and mineral distribution within the enamel was otherwise normal. Under light microscopy the ameloblasts exhibited an increase in vacuoles and dark granules in the supranuclear cytoplasm 2-12 hours after injection. At 12 hours a total disarray of the mineralizing front was evident and confirmed by SEM. However, 24 hours after injection a normal structure of the mineralizing front was regained. Ultrastructurally the organelles of the ameloblasts showed no changes from normal at any time interval. However, 2 hours after injection multivesicular bodies appeared frequently in the Tomes' processes and crystal density had diminished in the interrod enamel. At 8 hours a proteinaceous matrixdevoid of crystals was accumulating corresponding to interrod growth regions, whereas no obvious changes were recorded at the rod growth regions. At 12 hours the newly formed interrod enamel was thin and without crystals in some places. In such areas a granular, less-dense matrix was found and a band of small swellings of the interrod enamel was evident most likely corresponding to the time of injection. After 24 hours the cells and the mineralizing front appeared normal except in the interrod growth regions where the cell processes were still separated by wide intercellular spaces in which crystals were occasionally found in a fine granular matrix. These observations are discussed with particular reference on the known physico-chemical effects of HEBP on mineral formation. A possible direct cellular effect on the ameloblasts should be studied using radioautography and immunocytological techniques.

Ameloblasts↗
PubMed1998

High-Frequency/High-field electron spin echo envelope modulation study of nitrogen hyperfine and quadrupole interactions on a disordered powder sample

High-frequency/high-field (95 GHz/3.4 T) electron spin echo envelope modulation (ESEEM) experiments on single crystals and disordered samples of dianisyl-nitroxide (DANO) radicals are reported. At these high microwave frequencies (W-band), the anisotropic g-matrix of the nitroxide radical is resolved in the EPR spectrum. Additionally ESEEM modulations from other than nitrogen nuclei, such as protons, are highly suppressed at these frequencies, because they are too far from the cancellation condition for effective mixing of the nuclear spin functions. Therefore the nitrogen (14N) hyperfine and quadrupole coupling tensors could be determined without ambiguity from powder measurements. The results obtained were checked by ESEEM measurements on single crystals. Advantages and disadvantages of high-field ESEEM on nitrogen couplings are briefly discussed and compared with electron nuclear double resonance (ENDOR) and X-band ESEEM. Copyright 1998 Academic Press.

Journal Article↗
PubMed2005

Childhood asymmetric labium majus enlargement: mimicking a neoplasm.

We report a distinctive lesion of the labium majus resected in 14 girls from 3.9 to 13.2 years of age. All presented with enlargement of 1 or occasionally both labia majora. Radiographic imaging and surgical exploration showed expansion of the labium majus without definable borders. Grossly, specimens consisted of fibro-fatty tissue from 2 to 8 cm in greatest dimension. Microscopic examination revealed the usual constituents of vulvar soft tissue, with expansion of the fibrous component. Sparsely to moderately cellular interconnected bands encircled lobules of fat, blood vessels, and nerves. The bands consisted of plump and occasionally stellate or round fibroblasts immersed in an abundant pale myxoid matrix containing thin collagen fibers. These fibrous bands merged with thinner denser fibrous septa simlar to those seen in the vulva from age-matched controls. Elastic stains showed variably abundant thin parallel elastic fibers. Fibroblasts were immunohistochemically positive for estrogen and progesterone receptors. Electron microscopy showed fibroblasts with dilated rough endoplasmic reticulum cisternae and prominent nuclear fibrous laminae; extracellular matrix contained precollagen, collagen, elastic fibers, and numerous proteoglycan granules. Cytogenetic analysis of 3 lesions revealed a normal karyotype. Recurrence was observed in 7 (50%) patients, and regression was observed in 1 whose recurrence was not reexcised. Over an 11-year period at Children's Hospital (Boston, MA), these lesions represented 22% of all pediatric vulvar soft tissue masses and 3% of all vulvar lesions biopsied. We conclude that "childhood asymmetric labium majus enlargement" is a distinctive clinicopathologic entity of pre- and early puberty. Recognition of this fairly common lesion is important, since it may clinically, radiographically, and histologically mimic an infiltrative neoplasm. Its occurrence at an age roughly coincident with the time of breast budding, capacity for spontaneous regression, histologic architecture and composition of elements native to the vulva, expression of hormone receptors, and normal karyotype suggest that it is an asymmetric physiologic enlargement in response to hormonal surges of pre- and early puberty.

Adolescent↗
PubMed1979

Dynamics of enamel formation in the rat incisor tooth.

Enamel formation was reviewed by morphology and radioautography in rat incisors. Labeled amino acids and sugars were used as matrix precursors whereas labeled calcium monitored mineral deposition. All ameloblasts synthesize organic material, but only cells in the zone of secretion release labeled matrix. The pattern of matrix deposition indicates that enamel rods are elaborated by Tomes' processes within cavities formed by interrod partitions. The latter are elaborated by cytoplasmic projections from adjacent ameloblasts. Initially-labeled matrix is added as a band near the cells. With time the label randomizes throughout the entire immature enamel and most of it is lost in the zone of maturation. However, a glycoprotein component attributed to remnants of Tomes' process membrane persists in mature enamel. Labeled calcium is incorporated into crystals which grow at a uniform rate throughout the entire layer of enamel in the zone of secretion and up to the middle of the zone of maturation. The ribbon-like crystals are built close to the cell membrane and elongate as the cell recedes. Crystal elongation occurs in the same location as new matrix is deposited; that is, rod crystals are related to Tomes' processes and interrod crystals, to cytoplasmic projections. The crystals grow to full size mainly by thickening and this growth presumably displaces the organic matrix.

Ameloblasts↗
PubMed1991

Ligand binding to heme proteins: connection between dynamics and function.

Ligand binding to heme proteins is studied by using flash photolysis over wide ranges in time (100 ns-1 ks) and temperature (10-320 K). Below about 200 K in 75% glycerol/water solvent, ligand rebinding occurs from the heme pocket and is nonexponential in time. The kinetics is explained by a distribution, g(H), of the enthalpic barrier of height H between the pocket and the bound state. Above 170 K rebinding slows markedly. Previously we interpreted the slowing as a "matrix process" resulting from the ligand entering the protein matrix before rebinding. Experiments on band III, an inhomogeneously broadened charge-transfer band near 760 nm (approximately 13,000 cm-1) in the photolyzed state (Mb*) of (carbonmonoxy)myoglobin (MbCO), force us to reinterpret the data. Kinetic hole-burning measurements on band III in Mb* establish a relation between the position of a homogeneous component of band III and the barrier H. Since band III is red-shifted by 116 cm-1 in Mb* compared with Mb, the relation implies that the barrier in relaxed Mb is 12 kJ/mol higher than in Mb*. The slowing of the rebinding kinetics above 170 K hence is caused by the relaxation Mb*----Mb, as suggested by Agmon and Hopfield [(1983) J. Chem. Phys. 79, 2042-2053]. This conclusion is supported by a fit to the rebinding data between 160 and 290 K which indicates that the entire distribution g(H) shifts. Above about 200 K, equilibrium fluctuations among conformational substates open pathways for the ligands through the protein matrix and also narrow the rate distribution. The protein relaxations and fluctuations are nonexponential in time and non-Arrhenius in temperature, suggesting a collective nature for these protein motions. The relaxation Mb*----Mb is essentially independent of the solvent viscosity, implying that this motion involves internal parts of the protein. The protein fluctuations responsible for the opening of the pathways, however, depend strongly on the solvent viscosity, suggesting that a large part of the protein participates. While the detailed studies concern MbCO, similar data have been obtained for MbO2 and CO binding to the beta chains of human hemoglobin and hemoglobin Zürich. The results show that protein dynamics is essential for protein function and that the association coefficient for binding from the solvent at physiological temperatures in all these heme proteins is governed by the barrier at the heme.

Binding Sites↗
PubMed1983

Preparation and characterization of a human serum matrix suitable for quality control or reference materials.

We describe the preparation of a human serum based matrix suitable for inclusion in long-term control materials. The procedure entails the removal of cells, fibrin and lipoproteins from blood to produce a clear, stable material which has been stored frozen at -70 degrees C for up to 14 mth without any apparent deterioration. When incorporated into a quality control material, storage at 4 degrees and -20 degrees C may cause a change in several unstable constituents, but the material remains optically clear. A noticeable reduction in lipoprotein as a result of the preparative procedure is probably responsible for the continued clarity of the matrix. The nature of the matrix has been examined by polyacrylamide gel electrophoresis and does not reveal any unusual protein bands, whereas commercially available materials when similarly examined often reveal protein bands not present in normal serum. The matrix has been used to prepare control material for the Chemical Pathology Quality Assurance Programme Group of the Royal College of Pathologists of Australasia/Australian Association of Clinical Biochemists.

Blood Chemical Analysis↗
PubMed1998

A hemagglutinating variant of Prevotella melaninogenica isolated from the oral cavity.

Strains resembling Prevotella melaninogenica were isolated from healthy subjects and patients with periodontal disease and were identified using: a 5-test phenotypic screen; commercial identification kits; and a 16S rRNA-based polymerase chain reaction (PCR) method. Eleven clinical isolates closely resembling P. melaninogenica, and all from patients with periodontitis, were able to agglutinate erythrocytes. In the electron microscope, hemagglutinating isolates showed fimbria-like structures, that were not seen on non-hemagglutinating isolates. Some strains were further classified with PCR-restriction fragment-length polymorphism (RFLP) of 16S rRNA genes. Amplified 16S rDNA was digested using five different endonucleases, separated with agarose gel electrophoresis, stained and photographed. Photographs were then scanned, digitized and a distance matrix calculated using Dice coefficient, where the presence or absence of a band was used as a character. The distance matrix was plotted as a phenogram. At 70% similarity six clusters were seen. Type strains of separate Prevotella species did not fall into any cluster. Hemagglutinating isolates fell into three clusters: four clustered with the type strains of P. melaninogenica and Prevotella veroralis; four with other P. melaninogenica isolates and two hemagglutinating isolates clustered together Prevotella loescheii. The PCR-RFLP results showed that the hemagglutinating strains did not form a homogenous group inside the Prevotella genus.

Adult↗
PubMed1991

Protein secondary structure from Fourier transform infrared spectroscopy: a data base analysis.

An infrared (ir) method to determine the secondary structure of proteins in solution using the amide I region of the spectrum has been devised. The method is based on the circular dichroism (CD) matrix method for secondary structure analysis given by Compton and Johnson (L. A. Compton and W. C. Johnson, 1986, Anal. Biochem. 155, 155-167). The infrared data matrix was constructed from the normalized Fourier transform infrared spectra from 1700 to 1600 cm-1 of 17 commercially available proteins. The secondary structure matrix was constructed from the X-ray data of the seventeen proteins with secondary structure elements of helix, beta-sheet, beta-turn, and other (random). The CD and ir methods were compared by analyzing the proteins of the CD and ir databases as unknowns. Both methods produce similar results compared to structures obtained by X-ray crystallographic means with the CD slightly better for helix conformation, and the ir slightly better for beta-sheet. The relatively good ir analysis for concanavalin A and alpha-chymotrypsin indicate that the ir method is less affected by the presence of aromatic groups. The concentration of the protein and the cell path length need not be known for the ir analysis since the spectra can be normalized to the total ir intensity in the amide I region. The ir spectra for helix, beta-sheet, beta-turn, and other, as extracted from the data-base, agree with the literature band assignments. The ir data matrix and the inverse matrix necessary to analyze unknown proteins are presented.

Circular Dichroism↗
PubMed2005

Rapid identification of siderophores by combined thin-layer chromatography/matrix-assisted laser desorption/ionization mass spectrometry.

The investigation of a combined thin-layer chromatography/matrix-assisted laser desorption/ionization mass spectrometry (TLC/MALDI-MS) method for the analysis of siderophores from microbial samples is described. The investigated siderophores were enterobactin, ferrioxamine B, ferrichrome, ferrirhodin, rhodotorulic acid and coprogen. Solid-phase extraction was employed to recover the siderophores from the microbial samples. After visualization of the spots via spraying with ferric chloride or chrome azurol sulfonate assay solution, the MALDI matrix was applied to the gel surface. Several TLC/MALDI experimental parameters were optimized, such as type and concentration of MALDI matrix, as well as the type and composition of solvent to facilitate analyte transport from the inside of the TLC gel to the surface. The impact of these parameters on sensitivity, precision and ion formation of the various siderophores was studied. The detection limits for the investigated siderophores were in the range 1-4 pmol. These values were about 4-24 times higher than the detection limits obtained directly from stainless steel MALDI targets. The differences were most likely due to incomplete transport of the 'trapped' analyte molecules from the deeper layers of the TLC gel to the surface and into the matrix layer. In addition, chromatographic band broadening spread the analyte further in TLC as compared with the steel plates, resulting in less analyte per surface area. The identification of the siderophores was aided by concurrently applying a Ga(III) nitrate solution to the TLC plate during the visualization step. The resulting formation of Ga(III) complexes lead to distinctive (69)Ga/(71)Ga isotope patterns in the mass spectra. The versatility of the TLC/MALDI-MS assay was demonstrated by using it to analyze siderophores in a Pseudomonas aeruginosa sample. An iron-binding compound was identified in the sample, namely pyochelin (2-(2-o-hydroxyphenyl-2-thiazolin-4-yl)-3-methylthiazolidine-4-carboxylic acid).

Chromatography, High Pressure Liquid↗
PubMed2006

Multi-frequency ESR study of the polycrystalline phenoxyl radical of alpha-(3,5-di-tert-butyl-4-hydroxyphenyl)-N-tert-butylnitrone in the diamagnetic matrix.

Multifrequency (X-, Q-, and W-band) electron spin resonance (ESR) spectroscopy has been used to characterize the phenoxyl radical produced from alpha-(3,5-di-tert-butyl-4-hydroxyphenyl)-N-tert-butylnitrone, which is a new spin-trapping reagent. The X-band measurement did not resolve the powder-pattern ESR spectrum. Because of its higher resolution with g value, the Q-band ESR study revealed that the g factor has an axial-like symmetry and that the observed hyperfine structure in the Z-direction is caused by the nitrogen nucleus at the para-position. Furthermore, the results of the W-band ESR experiment more clearly distinguished the perpendicular components from the parallel component, resolving the perpendicular components into x and y components. The X-band powder spectrum was similar to the X-band ESR spectrum of the radical in a frozen solution of toluene. The computer simulation spectra performed using the obtained parameters fitted the experimental spectra well. A comparison of the amplitude of g( perpendicular)(gx, gy) with that of gz showed that the unpaired electron is delocalized over the pi-conjugated framework. Considering the hyperfine coupling constant, it was concluded that about 16% of the unpaired electron distributed over the nitrogen nucleus at the para-position. This study thus showed the significant potential of a multifrequency ESR approach to a powder sample radical in terms of its high resolution with g value.

Journal Article↗
PubMed2005

Implications of high-molecular-weight oligomers of the binary toxin from Bacillus sphaericus.

The mosquito-larvicidal binary toxin produced by Bacillus sphaericus is composed of BinB and BinA, which have calculated molecular weights of 51.4 and 41.9 kDa, respectively. NaOH extracts of B. sphaericus spores were analyzed using SDS-PAGE. Stained gels showed bands with molecular weights corresponding to those of BinB and BinA as well as two additional bands at 110 and 125 kDa. The matrix-assisted laser desorption/ionization mass spectrum of the purified 110 and 125 kDa bands showed two peaks at 104,160 and 87,358 Da that are assigned to dimers of BinB and BinA, respectively. Mass spectral analysis of trypsin-digested 110 and 125 kDa bands showed peaks at 51,328, 43,523, 43,130, and 40,832 Da that assigned to undigested BinB, two forms of digested BinB and digested BinA, respectively. Dynamic light scattering studies showed a solution of the purified 110 and 125 kDa bands was comprised almost entirely (99.6% of total mass) of a particle with a hydrodynamic radius of 5.6+/-1.2 nm and a calculated molecular weight of 186+/-38 kDa. These data demonstrate that the binary toxin extracted from B. sphaericus spores can exist in solution as an oligomer containing two copies each of BinB and BinA.

Animals↗
PubMed2003

Conformational substates and dynamic properties of carbonmonoxy hemoglobin.

Heme pocket dynamics of human carbonmonoxy hemoglobin (HbCO) is studied by Fourier transform infrared spectroscopy. The CO stretching band at various temperatures in the interval 300-10 K is analyzed in terms of three taxonomic A substates; however, in HbCO the band attributed to the A(1) taxonomic substate accounts for approximately 90% of the total intensity in the pH range 8.8-4.5. Two different regimes as a function of temperature are observed: below 160 K, the peak frequency and the bandwidth of the A(1) band have constant values whereas, above this temperature, a linear temperature dependence is observed, suggesting the occurrence of transitions between statistical substates within the A(1) taxonomic substate in this protein. The relationship between the heme pocket dynamics (as monitored by the thermal behavior of the CO stretching band), the overall dynamic properties of the protein matrix (as monitored by the thermal behavior of Amide II and Amide I' bands) and the glass transition of the solvent (as monitored by the thermal behavior of the bending band of water) is also investigated. From this analysis, we derive the picture of a very soft heme pocket of hemoglobin characterized by rather large anharmonic terms and strongly coupled to the dynamic properties of the solvent.

Amides↗
PubMed2003

Light transport through the band-edge states of Fibonacci quasicrystals.

The propagation of light in nonperiodic quasicrystals is studied by ultrashort pulse interferometry. Samples consist of multilayer dielectric structures of the Fibonacci type and are realized from porous silicon. We observe mode beating and strong pulse stretching in the light transport through these systems, and a strongly suppressed group velocity for frequencies close to a Fibonacci band gap. A theoretical description based on transfer matrix theory allows us to interpret the results in terms of Fibonacci band-edge resonances.

Journal Article↗