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PubMed1990

Determination of physiological levels of glucose in an aqueous matrix with digitally filtered Fourier transform near-infrared spectra.

A procedure is described for the measurement of clinically relevant concentrations of glucose in aqueous solutions with near-infrared (NIR) absorbance spectroscopy. A glucose band centered at 4400 cm-1 is used for this analysis. NIR spectra are collected over the frequency range 5000-4000 cm-1 with a Fourier transform spectrometer. A narrow-band-pass optical interference filter is placed in the optical path of the spectrometer to eliminate light outside this restricted range. This configuration provides a 2.9-fold reduction in spectral noise by utilizing the dynamic range of the detector solely for light transmitted through the filter. In addition, a novel spectral processing scheme is described for extracting glucose concentration information from the resulting absorbance spectra. The key component of this scheme is a digital Fourier filter that removes both high-frequency noise and low-frequency base-line variations from the spectra. Numerical optimization procedures are used to identify the best location and width of a Gaussian-shaped frequency response function for this Fourier filter. A dynamic area calculation, coupled with a simple linear base-line correction, provides an integrated area from the processed spectra that is linearly related to glucose concentrations over the range 1-20 mM. The linear calibration model accurately predicted glucose levels in a series of test solutions with an overall mean percent error of 2.5%. Based on the uncertainty in the parameters defining the calibration model and the variability of the magnitudes of the integrated areas, an overall uncertainty of 7.8% was estimated for predicted glucose concentrations.

Calibration↗

PubMed1982

Effects of beta-aminoproprionitrile on formation and mineralization of rat bone matrix.

Bones of 4-week-old Sprague-Dawley rats fed a diet containing 0.25% beta-aminoproprionitrile (beta-APN) for 21 days and injected with 3H-proline, 3H-tetracycline, and cold tetracycline at 5-, 10-, and 20-day intervals were analyzed for incorporation of 3H-proline and 3H-tetracycline. Tibial cross sections were examined by fluorescent microscopy to determine the linear bone apposition between intervals and the distribution and intensity of tetracycline bands. The incorporation of 3H-proline was similar in beta-APN-treated and control rats. Incorporation of 3H-tetracycline, however, was significantly lower in beta-APN-treated rats. Fluorescent microscopy of tibial cross sections showed a comparable amount of linear matrix apposition in control and treated rats. It is suggested that beta-APN does not inhibit the bone matrix formation but does interfere with its mineralization.

Aminopropionitrile↗

PubMed1998

Activation of extracellular matrix metalloproteinases in equine laminitis.

Samples of connective tissue obtained from the hoof of six laminitic and eight non-laminitic adult horses were analysed zymographically to investigate whether connective tissue matrix metalloproteinases are activated or induced during laminitis. The activity or matrix metalloproteinases was substantially greater in the tissues from the laminitic horses than in the tissues from the non-laminitic horses. A comparison of the collagenolytic activity in the laminitic and control tissues showed that collagenolytic activities corresponding to the 92 kDa (P < 0.001), 72 kDa (P < 0.01) and 66 kDa (P < 0.01) bands were induced in the laminitic tissues.

Animals↗

PubMed2003

Distribution and localization of vinculin-talin-integrin system and dystrophin-glycoprotein complex in human skeletal muscle. Immunohistochemical study using confocal laser scanning microscopy.

The vinculin-talin-integrin system and the dystrophin-glycoprotein complex (DGC) are two protein systems with structural and signaling functions, allowing interaction between muscle fibers and extracellular matrix. Although numerous studies have been conducted on these systems, their localization and distribution patterns along the nonjunctional sarcolemma are not clear. On this basis, we carried out an indirect immunofluorescence study on the vastus lateralis muscle of human adults not affected by neuromuscular diseases to better define these patterns. Our results showed that all tested proteins of the two systems have a costameric distribution; all tested proteins of the two systems colocalize with each other (about 90-95% of the cases); only alpha-sarcoglycan in a few cases (about 6%) does not colocalize with other proteins; in about 9-10% of the cases, dystrophin and beta-dystroglycan colocalize partially with other proteins; all tested proteins can be localized in different fibers, both in the region of the sarcolemma over I or A bands. The colocalization between the vinculin-talin-integrin and DGC systems may imply their functional interaction involving the structural aspect, by providing a stronger adhesion between sarcolemma and extracellular matrix in well-defined regions of the muscle fiber. Besides, their colocalization may suggest the existence of a mechanism of mutual modulation of the transmitted signals. This reciprocal control may determine, in different conditions, the prevalence of one system over another with a consequent transmission of different messages to the sarcolemma-associated cytoskeleton.

Dystrophin↗

PubMed2003

Comparative identification of prostanoid inducible proteins by LC-ESI-MS/MS and MALDI-TOF mass spectrometry.

Protein identification by MS is well-established. Mixtures of proteins from cell extracts are separated by either one- or two-dimensional gel electrophoresis, and specific bands or spots are subjected to in-gel digestion and subsequent analysis by MS. The two most common types of ionization used in MS are electrospray ionization (ESI) and matrix-assisted laser desorption/ionization (MALDI). When ESI is used, the sample is typically analyzed by inline HPLC-ESI-MS/MS with fragmentation of individual digest peptides, followed by database comparison between theoretical and experimental fragmentation patterns. MALDI-MS analysis is based on peptide mass mapping, with mass measurements of the digest peptides searched against a database of theoretical digests. We give here the results of a comparison between ESI-ion trap and MALDI-TOF (time-of-flight) analysis of 11-deoxy,16,16-dimethyl prostaglandin E(2) (DDM-PGE(2)) inducible proteins. Individual peptides identified by the two techniques differed, in general, but the resulting protein identification was the same. Slightly higher coverage of each protein was obtained by MALDI-TOF, but the MS/MS data were more definitive by requiring fewer peptides to assign a positive identification. Both methods effectively identified two proteins in the same gel band. The samples here are derived from a renal epithelial cell line (LLC-PK(1)) established from the New Hampshire minipig, a species poorly represented in the current database, and strategies and limitations for analyzing such species are discussed.

Amino Acid Sequence↗

PubMed1999

Separable contributions of ordered and disordered lipid fatty acyl chain segments to nuCH2 bands in model and biological membranes: a Fourier transform infrared spectroscopic study.

In this article, the assignment of the nu(C-H) stretching region of lipid molecules is revisited. This region is extensively used to follow lipid phase transitions, and especially the frequency shifts and bandwidth alterations in the nu(sym)CH2 band have been utilized in this respect. Here, we propose and prove that behind these phenomena there are pairs of component bands in the cases of both the nu(sym)CH2 and the nu(as)CH2 bands. The lower-frequency components of the pairs are assigned to the vibrations of CH2 groups on trans segments of the fatty acyl chains, while the higher-frequency components of the pairs are assigned to CH2 groups on gauche segments. To prove these assignments, we have shown that the nuCH2 frequencies are characteristic of the conformation of the lipid fatty acyl chain itself, and not the state of the whole lipid matrix. Curve fitting in fact revealed the conformer-specific components. With the use of singular value decomposition analysis we have demonstrated that the relative intensity changes in the components, and not the shifts in the whole bands, cause the observed shifts in the nuCH2 bands upon lipid phase transition. The results of this approach are presented for deuterium-saturated dioleoyl-phosphatidylcholine mixtures, for the gel --> liquid-crystalline phase transition of dipalmitoyl-phosphatidylcholine multilayers, and for a biological membrane, barley thylakoid. This refined assignment offers physically plausible reasoning for the observed phenomena and is able to explain frequency shifts and bandwidth changes observed previously upon lipid phase transitions, including their nonconcerted temperature dependences. In biological membranes, this interpretation allows the separation of protein- and membrane-dynamics-induced lipid conformational changes.

Cell Membrane↗

PubMed1998

Identification of a serum gelatinase associated with the occurrence of cerebral aneurysms as pro-matrix metalloproteinase-2.

BACKGROUND AND PURPOSE: Subarachnoid hemorrhage from intracranial aneurysm rupture produces a severe form of stroke. Extracellular matrix remodeling is associated with cerebral aneurysms and may play a role in the formation or rupture of these lesions. We previously reported a 3-fold increase in a 72-kDa serum gelatinase in a subgroup of aneurysm patients. The purpose of the present study was to further characterize and identify this gelatinase. METHODS: Serum samples were collected from surgical patients with intracranial aneurysms. The following series of experiments was designed to further characterize and identify the predominant serum gelatinase found in the subgroup of patients with increased gelatinase activity. Gelatin zymography was performed on native serum samples and compared with serum that had been pretreated with a known metalloproteinase activator (4-aminophenylmercuric acetate [APMA]). Gelatin zymography was repeated in the presence of a matrix metalloproteinase (MMP) inhibitor (EDTA) and a serine proteinase inhibitor (phenylmethylsulfonyl fluoride [PMSF]). Final identification was made by Western blotting with the use of monoclonal antibodies to MMP-2 and MMP-9. RESULTS: A consistent gelatinolytic band (72 kDa) was identified in all serum samples (n = 60). Pretreatment of the serum by APMA (n = 60) lowered the molecular weight of the band to 66 kDa. The band was inhibited by EDTA (n = 10) but not PMSF (n = 10), thus characterizing the circulating 72-kDa gelatinase as an inactive pro-MMP. Western blotting (n=20) identified the 72-kDa band as MMP-2. CONCLUSIONS: These findings confirm that the increased gelatinolytic activity observed in vitro in a subset of cerebral aneurysm patients is due to pro-MMP-2.

Adult↗

PubMed1997

Partial purification of HLAMP-1 provides direct evidence for the multicomponent nature of the particulate matrix associated with cardiac mesenchyme formation.

H-LAMP-1 is a 283 kDa protein that is involved in the transformation of endothelial cells into mesenchyme within the AV canal and proximal outflow tract of the heart. This protein is part of the particulate matrix that has been suggested to be composed of multicomponent complexes that have been termed cardiac adherons. However, to date no direct evidence has been provided that these proteins are complexed into an adheron-like particle. This report provides the first such evidence by showing that purification of hLAMP-1, under gentle conditions, results in the isolation of multiple bands of similar molecular weight within the fractions that contain anti-hLAMP-1 activity.

Animals↗

PubMed2001

Proteoglycans and glycosaminoglycan fine structure in the mouse tail tendon fascicle.

The isolated mouse tail tendon fascicle, a functional and homogenous volume of tendon extracellular matrix, was utilized as an experimental system to examine the structure function relationships in tendon. Our previous work using this model system demonstrated relationships between mean collagen fibril diameter and fascicle mechanical properties in isolated tail tendon fascicles from three different groups of mice (3-week and 8-week control and 8-week Mov13 transgenic) K.A. Derwin, L.J. Soslowsky, J. Biomech. Eng. 121 (1999) 598-604. These groups of mice were chosen to obtain tendon tissues with varying collagen fibril structure and/or biochemistry, such that relationships with material properties could be investigated. To further investigate the molecular details of matrix composition and organization underlying tendon function, we report now on the preparation, characterization, and quantitation of fascicle PGs (proteoglycans) from these three groups. The chondroitin sulfate/dermatan sulfate (CS/DS)-substituted PGs, biglycan and decorin, which are the abundant proteoglycans of whole tendons, were also shown to be the predominant PGs in isolated fascicles. Furthermore, similar to the postnatal maturation changes in matrix composition previously reported for whole tendons, isolated fascicles from 8-week mice had lower CS/DS PG contents (both decorin and biglycan) and a higher collagen content than 3-week mice. In addition, CS/DS chains substituted on PGs from 8-week fascicles were shorter (based on a number average) and richer in disulfated disaccharide residues than chains from 3-week mice. Fascicles from 8-week Mov13 transgenic mice were found to contain similar amounts of total collagen and total CS/DS PG as age-matched controls, and CS/DS chain lengths and sulfation also appeared normal. However, both decorin and biglycan in Mov13 tissue migrated slightly faster on sodium dodecyl sulfate polyacrylamide gel electorphoresis (SDS-PAGE) than the corresponding species from 8-week control, and biglycan from the 8-week Mov 13 fascicles appeared to migrate as a more polydisperse band, suggesting the presence of a unique PG population in the transgenic tissue. These observations, together with our biomechanical data [Derwin and Soslowsky, 1999] suggest that compensatory pathways of extracellular matrix assembly and maturation may exist, and that tissue mechanical properties may not be simply determined by the contents of individual matrix components or collagen fibril size.

Animals↗

PubMed1996

Soluble matrix of hen's eggshell extracts changes in vitro the rate of calcium carbonate precipitation and crystal morphology.

1. Extra and intramineral eggshell matrix proteins were solubilised before and after demineralisation by sequential extractions using guanidine hydrochloride and EDTA. 2. The intramineral electrophoretic profile of SDS-PAGE showed the presence of 80, 66, 43, 36 and 15 kDa bands with a predominance of a 17 kDa band. In the extramineral part, the major protein was the 15 kDa band. 3. The introduction of intramineral extract to a metastable solution of calcium carbonate delayed the rate of crystal growth. The delay in the rate of precipitation was elicited by a single fraction (MW 50-80 kDa), isolated by gel filtration chromatography, of eggshell extracts. Extramineral extracts had no effect. 4. Addition in vitro of intramineral eggshell extracts modified the morphology of calcite; the crystals aggregated and showed irregular surfaces. 5. These observations suggest that constituents of the eggshell matrix are involved in the control of calcite growth and crytallographic structure of the hen's eggshell.

Animals↗

PubMed1997

Angiostatin-converting enzyme activities of human matrilysin (MMP-7) and gelatinase B/type IV collagenase (MMP-9).

Angiostatin is one of the most potent inhibitors of angiogenesis. Reports have shown that metalloelastase, pancreas elastase, plasmin reductase, and plasmin convert plasminogen to angiostatin. However, the cleavage sites of plasminogen by those enzymes have not been determined. Here we demonstrate that two members of the human matrix metalloproteinase (MMP) family, matrilysin (MMP-7) and gelatinase B/type IV collagenase (MMP-9), hydrolyze human plasminogen to generate angiostatin fragments. The cleavage sites have been determined. The 58-kDa bands derived from plasminogen by MMP-7 and MMP-9 both have the N-terminal sequence KVYLSEXKTG, which corresponds to that of angiostatin. This N terminus is identical to that of the starting plasminogen itself and corresponds to residues 97-106 of prepro-plasminogen. The 42- and 38-kDa bands generated by MMP-7 both have the N-terminal sequence VVLLPNVETP, which corresponds to the amino acid sequence 467-476 of prepro-plasminogen, between kringle domain 4 and 5. MMP-9 cleaves plasminogen to generate a 42-kDa fragment with the N-terminal sequence PVVLLPNVE, 1 residue upstream of the MMP-7 cleavage site. These results indicate that MMP-7 and MMP-9 may regulate new blood vessel formation by cleaving plasminogen and generating angiostatin molecules.

Amino Acid Sequence↗

PubMed1992

Immunohistochemical and biochemical characterisation of the expression of a human embryonal carcinoma cell proteoglycan antigen in human germ cell tumours and other tissues.

In the embryonal carcinoma (EC) cell line GCT 27, monoclonal antibody GCTM-2 recognises an epitope on a 200 kD pericellular matrix keratan sulphate proteoglycan. Immunohistochemical analyses demonstrated staining of tissue sections from 21 out of 22 human non-seminomatous germ cell tumours, and from 22 out of 28 sections of seminomas. In normal human fetal tissues gut epithelium and muscle stained strongly, and certain other epithelia stained moderately. In adult tissues, the distribution of the epitope was similar, but staining intensity was weaker. Neoplastic tissues showed reactivity with embryonal rhabdomyosarcoma and colorectal carcinoma, but no other non-germ cell tumours. Immunofluorescence microscopy showed that GCTM-2 also stained cell lines from human colorectal carcinoma, embryonal rhabdomyosarcoma and choriocarcinoma. In contrast to EC cells the epitope in these other cell types required permeabilization of the cells to be visualised, and the protein bands in immunoblots lacked extensive modification with keratan sulphate and were smaller. Thus, GCTM-2 reacts with an epitope which has a previously unrecognised tissue distribution; its expression as a pericellular matrix proteoglycan is predominantly a characteristic of human EC cells.

Antibodies, Monoclonal↗

PubMed2005

Vibronic structure of the permanganate absorption spectrum from time-dependent density functional calculations.

The UV absorption spectrum of the permanganate anion is a prototype transition-metal complex spectrum. Despite this being a simple d0 Td system, for which a beautiful spectrum with detailed vibrational structure has been available since 1967, the assignment of the second and third bands is still very controversial. The issue can be resolved only by an elucidation of the intricate vibronic structure of the spectrum. We investigate the vibronic coupling by means of linear-response time-dependent density functional calculations. By means of a diabatizing scheme that employs the transition densities obtained in the TDDFT calculations in many geometries around Re, we construct a Taylor series expansion in the normal coordinates of a diabatic potential energy matrix, coupling 24 excited states. The simulated vibronic structure is in good agreement with the experimental absorption spectrum after the adjustment of some of the calculated vertical excitation energies. The peculiar blurred vibronic structure of the second band, which is a very distinctive feature of the experimental spectrum, is fully reproduced in the calculations. It is caused by the double-well shape of the adiabatic energy surface along the Jahn-Teller active e mode of the allowed 1E state arising from the second 1T2 state, which exhibits a Jahn-Teller splitting into 1B2 and 1E states. We trace the double-well shape to an avoided crossing between two diabatic states with different orbital-excitation character. The crossing can be explained at the molecular orbital level from the Jahn-Teller splitting of the set of 7t2{3d(xy), 3d(xz), 3d(yz)} orbitals (the LUMO + 1), to which the excitations characterizing the diabatic states take place. In contrast to its character in the two well regions, at Re the 2(1)T2 state is not predominantly an excitation to the LUMO + 1, but has more HOMO - 1 --> LUMO (2e = {3d(x2-y2), 3d(z2)}) character. The changing character of the 2(1)T2 - 1E state along the e mode implies that the assignment of the experimental bands to single orbital transitions is too simplistic intrinsically. This spectrum, and notably the blurring of the vibronic structure in the second band, can be understood only from the extensive configurational mixing and vibronic coupling between the excited states. This solves the long-standing assignment problem of these bands.

Journal Article↗

PubMed1975

Correspondence of silver nitrate staining patterns in decalcified bone withe the microradiographic image.

A procedure for differential staining of decalcified bone with silver nitrate showed major histological features which appeared to correspond closely to microradiographic images. The extent to which this is actually the case was investigated directly by preparing microradiographs of ground sections of baboon and dog radii and then decalcifying and staining the same sections. The many detailed similarities indicate that this staining procedure is a useful adjunct to microradiography. Thus, poorly mineralized osteons or layers of circumferential lamellae are darker stained by silver nitrate, and the variably mineralized layers of circumferential lamellae are closely duplicated by light and dark bands in the stained sections. These similarities imply that there is a relationship between the mineral density of bone and some condition of the organic matrix which is probably related to maturation changes in the collagen.

Age Factors↗

PubMed2005

Fine structure of the mineralized teeth of the chiton Acanthopleura echinata (Mollusca: Polyplacophora).

The major lateral teeth of the chiton Acanthopleura echinata are composite structures composed of three distinct mineral zones: a posterior layer of magnetite; a thin band of lepidocrocite just anterior to this; and apatite throughout the core and anterior regions of the cusp. Biomineralization in these teeth is a matrix-mediated process, in which the minerals are deposited around fibers, with the different biominerals described as occupying architecturally discrete compartments. In this study, a range of scanning electron microscopes was utilized to undertake a detailed in situ investigation of the fine structure of the major lateral teeth. The arrangement of the organic and biomineral components of the tooth is similar throughout the three zones, having no discrete borders between them, and with crystallites of each mineral phase extending into the adjacent mineral zone. Along the posterior surface of the tooth, the organic fibers are arranged in a series of fine parallel lines, but just within the periphery their appearance takes on a "fish scale"-like pattern, reflective of the cross section of a series of units that are overlaid, and offset from each other, in adjacent rows. The units are approximately 2 microm wide and 0.6 microm thick and comprise biomineral plates separated by organic fibers. Two types of subunits make up each "fish scale": one is elongate and curved and forms a trough, in which the other, rod-like unit, is nestled. Adjacent rod and trough units are aligned into large sheets that define the fracture plane of the tooth. The alignment of the plates of rod-trough units is complex and exhibits extreme spatial variation within the tooth cusp. Close to the posterior surface the plates are essentially horizontal and lie in a lateromedial plane, while anteriorly they are almost vertical and lie in the posteroanterior plane. An understanding of the fine structure of the mineralized teeth of chitons, and of the relationship between the organic and mineral components, provides a new insight into biomineralization mechanisms and controls.

Animals↗

PubMed1996

A modified Coomassie blue staining of proteins in polyacrylamide gels with Bismark brown R.

A rapid and sensitive protein staining method employing a mixed dye technique has been developed. Solutions of Coomassie brilliant blue R-250 (CB, 0.2%) and Bismark brown R (BBR, 0.05%) were mixed in the volume ratio of 1:0.75 for staining (final molar ratio, 4.5:1). In this staining, BBR inhibits the binding of CB to gel matrix by forming ion-pairing complex with excess CB; therefore, it reduces staining/destaining times and also enhances the staining effect of CB on protein band. As a result, the mixed dye staining enables complete staining/destaining within 20/25 min and detection of up to 25 ng of bovine serum albumin.

Animals↗

PubMed2002

Purification and characterization of chitinases from the nematophagous fungi Verticillium chlamydosporium and V. suchlasporium.

Culture filtrates of the nematophagous fungi Verticillium chlamydosporium and V. suchlasporium growing on colloidal chitin showed increasing chitinolytic activity and production of two (32- and 43-kDa) main proteins. Maximum activity was found 18-20 days after inoculation, but V. suchlasporium always displayed higher activity. Zymography of such filtrates on carboxymethyl-chitin-Remazol brilliant violet 5R/acrylamide gels showed five bands of substrate degradation for V. suchlasporium and three for V. chlamydosporium. Filtrates with maximum activity were chromatographed on macroporous cross-linked chitin affinity matrix, showing a peak of main (50-60%) activity, which only contained a 43-kDa protein for both fungi. Zymography and colloidal chitin degradation showed that it was a single endochitinase (CHI43) with optimum pH range of 5.2-5.7. The main isoforms had pIs of 7.6 for V. suchlasporium and 7.9 for V. chlamydosporium. Eggs of the nematode Globodera pallida treated with CHI43 and the serine protease P32 from V. suchlasporium alone or in combination showed surface damage in comparison with controls when examined by scanning electron microscopy.

Animals↗

PubMed1986

[Proteins of bee honey. VI. Isoelectric focusing of amylase in various kinds of honey].

The isolated honey amylase was characterized by preparative and analytical isoelectric focusing. An interesting aspect of the preparative isoelectric focusing was the reduction of iodine by Ampholines which were used for building up a pH-gradient, giving a false increase in apparent amylase activity as determined by the iodine/starch reaction. Dextran gels were not suited for the matrix, because interactions with the enzyme disturb the focusing. From the analytical isoelectric focusing of isolated honey amylase in ultrathin layer Polyacrylamide gels 10 protein bands resulted. A newly developed zymogram technique was positive for amylase activity in all 10 protein bands.

Amylases↗