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PubMed2001

A study of HAp/PLLA composite as a substitute for bone powder, using FT-IR spectroscopy.

Chemically synthesized hydroxyapatite/poly-L-lactide (HAp/PLLA) composite biomaterial was studied in vivo. The biocomposite was implanted into Balb/c Singen mice and after 1 and 3 weeks removed from their organisms and analyzed by the FT-IR spectroscopy. After 1 week of testing in vivo the implanted sample gave a spectrum in which absorption bands arising from newly formed functional groups of amine and peptide can be seen. After 3 weeks, a spectrum with pronounced absorption bands at 3420 and 1650cm(-1) assigned to newly generated collagen, a component of the extracellular connective-tissue matrix, was registered. Also, decrease of the intensity absorption band at 1760cm(-1) originating from the C=O group of PLLA indicates bioresorption of the PLLA used. Analysis of the microstructure of the sample surface by scanning electron microscopy before and after implantation revealed bioresorption of the PLLA polymer phase and generation of collagen fibers at the sites of implanted bioresorptive PLLA. A mixture of autologous bone powder and HAp/PLLA biocomposite was also examined. After implantation, the same final products as in the case of HAp/PLLA composite biomaterial used alone were found.

Animals↗
PubMed1984

Pepsin-generated type VI collagen is a degradation product of GP140.

A major extracellular matrix glycoprotein, GP140 , synthesized by WI-38 human lung fibroblasts has previously been shown to be collagen-like. A form of GP140 that is related to extracellular matrix GP140 both antigenically and in apparent molecular mass was isolated from human placenta. Types I-VI collagen were isolated from human tissues by limited pepsin digestion, selective salt precipitation, and chromatography. Immunoblot analysis of the collagens and GP140 utilizing affinity-purified polyclonal antiserum directed against extracellular matrix GP140 demonstrated cross-reactivity of antibodies with type VI collagen. Both type VI collagen and matrix GP140 could be digested with bacterial collagenase following reduction with dithiothreitol but were collagenase insensitive under nonreducing conditions, unlike types I-V collagen. Placental and matrix GP140 and type VI collagen were shown to have receptors for 125I-labeled Lens culinaris lectin. Pepsin digestion of WI-38 extracellular matrix GP140 yielded a 64,000-dalton band which co-migrated with subunits of reduced type VI collagen on Coomassie-stained sodium dodecyl sulfate-polyacrylamide gel electrophoresis gels, reacted with anti- GP140 antiserum and 125I-labeled L. culinaris lectin, and was collagenase-sensitive only under reducing conditions. CNBr fragmentation of extracellular matrix GP140 , the 64,000-dalton pepsin-resistant peptide of GP140 and type VI collagen followed by immunoblot analysis using anti- GP140 revealed similarities in peptide maps of GP140 and type VI collagen. Our data strongly suggest that GP140 and type VI collagen share characteristics that differ from those of other collagen types and that intermolecular disulfide bonding appears to stabilize these molecules in their native unreduced form, thus conferring collagenase resistance. Finally, the SC1 and SC2 subunits of type VI collagen appear to be generated by pepsin digestion of GP140 .

Adult↗
PubMed1973

Localization of the enzymes of ketogenesis in rat liver mitochondria.

The localization of the enzymes of ketogenesis in isolated rat liver mitochondria has been investigated. Mitochondrial subfractions were isolated after disruption of this subcellular organelle by (a) hypotonic lysis in water, which permitted the ultracentrifugal separation of the soluble and membranous compartments of the mitochondrion, or by (b) a procedure involving swelling, contraction, and ultrasonic treatment, which permitted the isolation from discontinuous sucrose gradients of subfractions rich in intermembrane space protein, outer membrane, and inner membrane-matrix particles. Two membrane subfractions were invariably present as distinct bands at the lower interface of the discontinuous gradient. The upper of these two bands was found to be a highly purified preparation of outer mitochondrial membrane. Subfractions rich in matrix and in inner membrane were isolated from inner membrane-matrix particles after hypotonic treatment. The content of the various mitochondrial compartments in all subfractions was assessed from their enzymic and electron microscopic characteristics. The ketogenic activity of each subfraction was determined by measuring its capacity to form ketone bodies from acetyl CoA. The activity of this process was markedly enhanced by dithiothreitol. These measurements of ketone body formation, together with assays of individual enzymes of the ketogenic pathway, show that thiolase, HMGCoA synthase, and HMGCoA cleavage enzyme are localized in the matrix of the inner membrane-matrix particles. The rates of ketone body formation indicate that the HMGCoA synthase is the rate-limiting enzyme of the pathway in subfractions of high matrix content. Studies with sodium chloride indicate that a large portion of the HMGCoA synthase, which remains present in membrane subfractions derived from water-treated mitochondria, is bound by ionic interaction to component(s) of the membrane.

Acetyltransferases↗
PubMed1990

Rat brain N-acetylated alpha-linked acidic dipeptidase activity. Purification and immunologic characterization.

N-Acetylated alpha-linked acidic dipeptidase (NAALA dipeptidase) is a membrane-bound metallopeptidase that cleaves glutamate from the endogenous neuropeptide N-acetyl-L-aspartyl-L-glutamate. In this report, we have solubilized NAALA dipeptidase activity from synaptosomal membranes with Triton X-100 and purified it to apparent homogeneity by sequential column chromatography on DEAE-Sepharose, CM-Sepharose, and lentil lectin-Sepharose. This procedure resulted in a 720-fold purification with 1.6% yield. The purified ezyme migrated as a single silver-stained band on a sodium dodecyl sulfate gel with an apparent molecular weight of 94 kDa. Using an enzymatic stain to visualize NAALA dipeptidase activity within a gel matrix, we have confirmed that the 94-kDa band is, indeed, NAALA dipeptidase. The purified enzyme was characterized and found to be pharmacologically similar to NAALA dipeptidase activity described previously in synaptosomal membrane extracts. Using the purified NAALA dipeptidase as antigen, we have raised specific and high titer polyclonal antibodies in guinea pig. Immunocytochemical studies show intense NAALA dipeptidase immunoreactivity in the cerebellar and renal cortices.

Animals↗
PubMed1992

A monoclonal antibody produced against a rat esophageal carcinoma cell line reacts with an integrin-like molecule expressed by rat epithelial cells.

A monoclonal antibody, designated MAb-5A IIgG1), was generated against a tumorigenic rat esophageal epithelial cell line, B-2T. MAb-5A reacted with a series of non-tumorigenic and tumorigenic epithelial cell lines derived from F-344 rat esophagi or tracheas. However, the highest level of antigen expression was detected on tumorigenic rat epithelial cell lines. A trace amount of antigen was detected in primary cultures of normal rat epithelial cells derived from either esophagi or tracheas. MAb-5A did not react with rat fibroblasts. MAb-5A reacted with B-2T derived tumor tissues propagated in vivo but showed only slight reactivity with normal rat esophageal epithelial tissues. Cell surface radioiodination, extraction and immunoprecipitation experiments were conducted to characterize the antigen molecule. Analysis of the immunoprecipitates by SDS-PAGE and autoradiography revealed two protein bands with mobilities corresponding to approximately 140 and 120 kDa, respectively. Under reducing conditions the 140 kDa band shifted to approximately 120 kDa whereas the 120 kDa band shifted upward to approximately 130 kDa. The non-reduced/reduced mobilities of these bands suggest that they may be members of the integrin family of matrix receptors. A polyclonal antibody to the beta 1 subunit immunoprecipitated two similar bands detected by MAb-5A, further suggesting that the antigen complex may be related to members of the integrin superfamily.

Animals↗
PubMed2005

Nanoclusters in polymer matrices prepared by co-deposition from a gas phase.

This paper reviews the fabrication of organic and metal nanoclusters in polymer matrices by three co-deposition techniques. In particular, the structure and properties of polytetrafluoroethylene (PTFE), polychlortrifluoroethylene (PCTFE), polyparaphenylene sulphide (PPS), polystyrene (PS) and polyparaxylylene (PPX) films, containing gold (Au) and dye clusters are discussed. For the first time, dye-filled polymers and multi-component films, consisting of both Au nanoparticles and dye molecules, dispersed in the PTFE matrix were studied. A low temperature plasma was used for film structure modification. Cluster formation process was studied using optical spectroscopy in situ. Transmission electron microscopy (TEM), atomic force microscopy (AFM) and ellipsometry were used for characterisation of the grown films. During Au-PTFE film growth plasmon band shifted from 460-480 nm to 560 nm. Au cluster diameter was in the 3-7 nm range. Plasma treatment of the vapours led to formation of smaller, but more aggregated clusters. During Au-PPS film deposition a two-step growth mechanism was discovered. At the beginning of film growth the plasmon band at 540 nm appeared, but as thickness increased, the band at 430 nm dominated. Without plasma treatment a disordered mixture was deposited, while with plasma treatment large Au aggregates confined with PPS matrix having plasmon band at 620 nm were formed. Dye cluster formation depends on the dye ability to aggregate, its concentration and the properties of the polymer matrix. But cluster formation can also be tuned by varying the deposition conditions. Laser beam evaporation promoted cluster formation, while plasma treatment and dilution in a polymer matrix prevented cluster formation. In all cases both equilibrium and non-equilibrium film structure can be formed using kinetic factor. Asymmetric molecules with bulky substituents were oriented in polymer matrices by applying an electric field in situ or by corona poling. These molecules did not aggregate even at high dye load. The films exhibited second harmonic generation, which demonstrated chromophore orientation in the polymer matrices.

Coloring Agents↗
PubMed1989

Cartilage resorption and endochondral bone formation during the development of long bones in chick embryos.

Cartilage resorption during long bone development in the chick embryo varies in several crucial aspects from that in mammals. Cartilage does not calcify prior to resorption, the pattern of vascular tunnelling is not as regular as that in mammals and no distinct growth plate or secondary ossification centre is apparent. Primary cartilage resorption is preceded by diffusion of substances which produce a change in the cartilage matrix and necrosis of adjacent chondrocytes. Mononuclear phagocytes resorb the bulk of uncalcified cartilage, but resorption is slowed down by the formation of an osteoid band along the walls of the marrow tunnels. This prevents resorbing cells from gaining access to the cartilage matrix. If this osteoid band is in alignment with the trabecular structure, it may contribute to structural bone. In some areas chondrocytes transform into, or are replaced by, bone-producing cells and osteoid is observed within the chondrocyte lacunae. Some calcification of cartilage is observed after 16 days in ovo, but this is independent of cartilage resorption. Remnants of calcified cartilage frequently persist in the marrow cavity and multinucleated chondroclasts are required to resorb these remnants.

Acid Phosphatase↗
PubMed2001

The first stage of transforming growth factor beta1 activation is release of the large latent complex from the extracellular matrix of growth plate chondrocytes by matrix vesicle stromelysin-1 (MMP-3).

Transforming growth factor beta-1 (TGF-beta1) is secreted in a biologically inactive form and stored in the extracellular matrix as a 290 kDa complex consisting of the mature TGF-beta1 homodimer (Mr 25 kDa), the latency-associated peptide (LAP; Mr 75 kDa), and the latent TGF-beta1 binding protein-1 (LTBP1; Mr 190 kDa). Latent TGF-beta1, composed of these three components, is known as the "large latent TGF-beta1 complex." In contrast, latent TGF-beta1 without LTBP1 is known as "small latent TGF-beta1." For all latent forms, dissociation of the TGF-beta1 homodimer from LAP is necessary for growth factor activation and acquisition of biological activity. Matrix vesicles produced by growth plate chondrocytes contain matrix metalloproteinases that can activate small latent TGF-beta1. The enzyme responsible for this is matrix metalloproteinase-3 (MMP-3), although matrix vesicles also contain MMP-2 and plasminogen activator. The present study tested the hypothesis that matrix vesicle enzymes are also involved in the release of the large latent TGF-beta1 complex stored in the extracellular matrix. Matrix vesicles were isolated from cultures of resting zone and growth zone chondrocytes and metalloproteinases present in the matrix vesicles extracted with guanidine-HCl. Chondrocyte extracellular matrices were prepared by lysing confluent cultures and removing the lysed cells. The matrices were incubated with matrix vesicle extracts and the release of total and active TGF-beta1 was determined. To determine if MMP-2 or MMP-3 was involved in the release, matrix vesicle extracts were preincubated with anti-MMP-2 antibody or anti-MMP-3 antibody to selectively deplete the enzyme activity. Matrices were also treated with rhMMP-2 or rhMMP-3. To determine the identity of the released protein(s), digests were separated on SDS-polyacrylamide gels and Western blotting analysis was performed using a specific antibody to LTBP1. Matrix vesicle extracts released both active and total (=latent + active) TGF-beta1 in a time-dependent manner, with peak release after 1 hour of incubation. The amount of total TGF-beta1 released was 10 times higher than the release of active TGF-beta1. The effect of the matrix vesicle extracts was dose-dependent; in addition, the amount and ratio of active to total TGF-b1 released was very similar, irrespective of the source of matrix or matrix vesicle extracts. Pre-incubation of matrix vesicle extracts with anti-MMP-3 antibody blocked the release of active and total TGF-beta1, whereas pre-incubation with pre-immune IgG or anti-MMP-2 antibody had no effect. The addition of rhMMP-3, but not rhMMP-2, caused a dose-dependent increase in the release of total, but not active, TGF-beta1. Western analysis confirmed that both matrix vesicle extracts and rhMMP-3 released the large latent TGF-beta1 complex from the matrix. In addition to the expected 290, 230, and 190 kDa bands, samples run without reduction also contained proteins of molecular weights 110 and 50 kDa that reacted with the anti-LTBP1 antibody. When these same samples were electrophoresed after reduction, the high molecular weight immunoreactive bands disappeared and three bands of molecular weight 75, 32, and 25 kDa were observed. These results indicate that matrix vesicles contain enzymes, especially MMP-3, which are responsible for the release of TGF-beta1 from the matrix, most of which is in latent form. Further, the data suggest that release of the large complex occurs via cleavage at several novel sites in the 130 kDa LTBP1 molecule. Since matrix vesicle MMP-3 is also able to activate small latent TGF-beta1, these results suggest that the large latent TGF-beta1 complex protects against activation of the small latent TGF-beta1. Thus, the data suggest that release of the large latent TGF-bl complex from the matrix and activation of the latent growth factor are only two steps of what must be at least a three-step process.

Animals↗
PubMed1988

Preparative elution of proteins blotted to Immobilon membranes.

Conditions for the preparative elution of proteins from Immobilon membranes after transfer of proteins to this matrix from sodium dodecyl sulfate-polyacrylamide gels have been established. Proteins were completely eluted from the membrane at room temperature by short incubation in 50 mM Tris-HCl, pH 9.0, containing 2% SDS and 1% Triton X-100. Good protein recoveries were also obtained in the same buffer containing 1% Triton X-100 only. The efficiency of elution was practically independent of the molecular weight of proteins, the method allowed for the precise excision of protein bands, and the proteins eluted from the matrix were not degraded. In some cases it was possible to recover enzymatic activity of the eluted proteins.

Electrophoresis, Polyacrylamide Gel↗
PubMedDate not supplied

[The nature and characteristics of valence fluctuations of the functional groups in the organic structure of normal dentin and in pathology].

Biopsied coronal dentin was studied in 50 permanent teeth in healthy individuals and patients with caries and pulpitis. Valent undulations of functional groups of protein matrix of dentin were studied. The characteristic absorption bands reflecting the chemical links stabilizing the protein molecular structure were determined. The course of chemical links changes was followed in caries and pulpitis which suggested the increased pathological changes in the organic matrix of coronal dentin.

Adult↗
PubMed1996

Plasticity in epithelial polarity of renal intercalated cells: targeting of the H(+)-ATPase and band 3.

The intercalated cell is an epithelial cell of the renal collecting tubule that is specialized for H+ and HCO3- transport. These cells exist as two types, alpha and beta. The alpha-cell secretes H+ into the lumen by an apical H(+)-ATPase and a basolateral Cl-/HCO3- exchanger that is a form of band 3 protein (AE1). The beta-cell secretes HCO3- into the lumen by an apical Cl-/HCO3- exchanger and a basolateral H(+)-ATPase. In a previous study, it was suggested that a reversal in epithelial polarity of these cells occurs during the response of the kidney to an acid load (G.J. Schwartz, J. Barasch, and Q. Al-Awqati. Nature Lond. 318: 368-371, 1985). Recent studies, however have shown that there are many other subtypes where the distribution of these two proteins does not fit into this neat bipolar classification. This group of investigators recently generated an immortalized cell line of the beta-intercalated cell and found that the apical Cl-/HCO3- exchanger is also AE1. Furthermore, when these cells were seeded at high densities, the polarized targeting of the apical band 3 was reversed to the basolateral membrane. This was produced by the secretion of extracellular matrix protein that by themselves were capable of reversing the polarity of band 3 (J. S. van Adelsberg, J. C. Edwards, J. Takito, B. Kiss, and Q. Al-Awqati. Cell 76: 1053-1061, 1995). A large new extracellular matrix protein, hensin, was identified and found to be present exclusively in the collecting tubule. The extensive recent literature on the biology of alpha- and beta-intercalated cells is reviewed here and found to be compatible with the idea of the reversal of polarity as a mechanism for the regulation of H+ secretion by the tubule.

Animals↗
PubMed2005

Infrared identification of matrix isolated H2O.O2.

Theoretical studies of the H2O.O2 complex have been carried out over the past decade, but the complex has not previously been experimentally identified. We have assigned IR vibrations from an H2O.O2 complex in an inert rare gas matrix. This identification is based upon theoretical calculations and concentration dependent behavior of absorption bands observed upon co-deposition of H2O and O2 in argon matrixes at 11.5 +/- 0.5 K. To aid assignment, we have used a harmonically coupled anharmonic oscillator local mode model with an ab initio calculated dipole moment function to calculate the OH-stretching and HOH-bending frequencies and intensities in the complex. The high abundance of H2O and O2 makes the H2O.O2 complex likely to be significant in atmospheric and astrophysical chemistry.

Journal Article↗
PubMed1996

Electrophoretic analysis of mammalian hair keratins.

Keratins extracted from the hair of several mammals were characterized by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) and isoelectric focusing (IEF). By SDS-PAGE, most differences between species were detected in the position and intensity of polypeptide bands with MW in the range 30-10 KDa (high sulphur keratins, hair matrix proteins, HMP). By IEF, differences were found in the intensity of polypeptide bands in the acidic pH range (< 5.1). Electrophoretic techniques could therefore have a taxonomic usefulness.

Animals↗
PubMed2006

Physicochemical characteristics of quinupramine in the EVA matrix.

Ethylene-vinyl acetate (EVA) is widely used as a membrane or matrix for transdermal drug delivery systems. In an attempt to determine the state of a drug in the EVA matrix, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and thermal analysis of the quinupramine-EVA matrix were carried out and the results were compared with those of a physical mixture of quinupramine and EVA at the same ratio. The 1:2 matrix of quinupramine with EVA was prepared using the casting method. The XRD pattern of the quinupramine test preparations revealed that the pure quinupramine was crystalline in nature, whereas the quinupramine in the EVA matrix was an amorphous form, which leads to increased drug release. The FT-IR spectra of quinupramine in the physical mixture showed absorption bands at around 3000-3050 cm(-1) whereas these absorption bands were not observed in the quinupramine-EVA matrix. The thermal studies of quinupramine in the physical mixture showed an endothermic peak at 154-156 degrees C, which is the melting point of the drug, but there was no such endothermic peak observed in the EVA matrix. In conclusion, the physicochemical interactions between quinupramine and EVA, might occur at the molecular level, and that quinupramine was not crystalline in the EVA matrix.

Administration, Cutaneous↗
PubMed2001

Matrix metalloproteinase activities of turkey (Meleagris gallopavo) bile.

The bile from turkey (Meleagris gallopavo) gall bladders was found to contain substantial matrix metalloproteinase (MMP) activities using gelatin, collagen, and casein substrate zymography, [3H]labeled collagen degradation assays, and gelatin-agarose affinity purification. Five major bands corresponding to approximate M(w) of 64, 60, 46, 40 and 36 kDa showed gelatinolytic activities. On incubation with p-aminophenylmercuric acetate or thimerosal, the densities of both the 64- and 46-kDa bands decreased with increasing intensities of the 60- and 40-kDa bands. Both the 64- and 60-kDa bands showed collagenolytic activities whereas the caseinolytic activities appeared as diffuse bands corresponding to M(w) of approximately 60, 40 and 36 kDa. Using [3H]collagen as substrate, the bile enzymes showed both a time and concentration-dependent degradation, which could be inhibited by the MMP inhibitors such as EDTA, phenanthroline, and N-[(2R)-2-(hydroxyamido carbonylmethyl)-4-methylpentanonyl]-L-tryptophan methylamide, but not by serine and cysteine protease inhibitors like trans-epoxysuccinyl-L-leucylamido-(4-guanidino)butane, phenylmethylsulfonyl fluoride or leupeptin. Both 60- and the 40-kDa gelatinolytic bands showed affinity adsorption to a gelatin-agarose matrix. The physiological roles of bile MMPs are not clear, but their involvement in the digestive functions of birds are likely.

Animals↗
PubMed2006

Spectroscopic study of substrate binding to the carbonmonoxy form of dehaloperoxidase from Amphitrite ornata.

Dehaloperoxidase (DHP) is a globular heme enzyme found in the marine worm Amphitrite ornata that can catalyze the dehalogenation of halophenols to the corresponding quinones by using hydrogen peroxide as a cosubstrate. Its three-dimensional fold is surprisingly similar to that of the oxygen storage protein myoglobin (Mb). A key structural feature common to both DHP and Mb is the existence of multiple conformations of the distal histidine. In DHP, the conformational flexibility may be involved in promotion of substrate and cosubstrate entry and exit. Here we have explored the dynamics of substrate binding in DHP using Fourier transform infrared spectroscopy and flash photolysis. A number of discrete conformations at the active site were identified from the appearance of multiple CO absorbance bands in the infrared region of the spectrum. Upon photolysis at cryogenic temperatures, the CO molecules are trapped at docking sites within the protein matrix, as inferred from the appearance of several photoproduct bands characteristic of each site. Substrate binding stabilizes the protein by approximately 20 kJ/mol. The low yield of substrate-bound DHP at ambient temperature points toward a steric inhibition of substrate binding by carbon monoxide.

Animals↗
PubMed2004

Impression matrix technique for cusp replacement using direct composite resin.

UNLABELLED: Placement of Class II composite resin restorations often presents unique challenges in achieving proper contour and contact. Although the use of sectional bands has provided solutions to these problems, their use typically is limited to more ideal cavity preparations. With more extensive loss of tooth structure, recreating the natural tooth contours and contacts with direct resin composite can be difficult. Typically an indirect restoration is the treatment of choice when a cusp is lost. However, situations may arise that require the use of direct resins for cusp replacement. This article describes the use of an impression matrix to facilitate the replacement of missing tooth structure and allow the dentist to use sectional bands in certain cusp loss situations. CLINICAL SIGNIFICANCE: When applicable, the impression matrix provides a significant saving in time and effort in cusp replacement with direct composite resins.

Bicuspid↗
PubMed1999

HDO and D2O Low Pressure, Long Path Spectra in the 600-3100 cm-1 Region.

High-resolution spectra of gas mixtures of HDO, D2O, and H2O were obtained with a Fourier-transform spectrometer with path lengths up to 433 m. The spectra were analyzed to obtain line positions and strengths of over 6000 transitions of HDO and D2O. For HDO, these included the (000)-(000), (020)-(010), and (100)-(010) bands of HD16O and the (010)-(000) bands of HD16O, HD17O, and HD18O. Several of these assignments are reported for the first time. Of interest was the extended coverage of the A-type transitions of the (010)-(000) band of HD16O. This is the only A-type infrared band of any of the water vapor species (HDO, D2O, and H2O) that is not involved in interactions with other bands. By this token, the A-type dipole-moment expansion matrix elements can be tested without involving perturbation theory. The measured linestrengths of the interacting bands, (020)-(010) and (100)-(010), were analyzed using a full perturbation treatment. Strong localized Coriolis interactions affected only a few observed transitions. Copyright 1999 Academic Press.

Journal Article↗