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PubMedDate not supplied

[Heterogeneous distribution of influenza A matrix protein in polyacrylamide gel, detected using an immunoblotting method with monoclonal antibodies].

The immune blotting method using monoclonal antibodies to Ml protein showed protein Ml to migrate in several bands in polyacrylamide gel electrophoresis (PGE) of influenza A virus polypeptides. The heterogeneous distribution of Ml protein in PGE is due to the formation of aggregates: dimers, trimers, and polymers of a higher order. The capacity of Ml protein for aggregation is typical not of all influenza virus strains and most likely is not associated with gel overloading. Since dimers and trimers of Ml protein comigrate in the gel with virus-specific proteins such as NP and proteins of a polymerase complex, this circumstance should be take into consideration in using PGE for isolation of pure influenza virus proteins.

Animals↗
PubMedDate not supplied

Experimental diabetes and left ventricular hypertrophy: effects of beta-receptor blockade.

BACKGROUND: Left ventricular hypertrophy involves growth of cardiomyocytes, as well as remodeling of extracellular matrix proteins (ECMPs). Several metabolic abnormalities may be triggered secondary to hyperglycemia in diabetes. The effects of combined supravalvular aortic banding and diabetes mellitus on the rat heart were investigated in order to detect possible synergistic effects of these two conditions. Moreover, this study focused on the impact of beta-adrenoceptor blockade with carvedilol (C) on the expression of ECMPs. METHODS: Sixty male Wistar rats were allocated to six groups: control (CON), CON+C, streptozotocin (65 mg/kg iv)-induced diabetes (D), D+C, aortic stenosis (AS)+D and AS+D+C. Follow-up was 6 weeks. RESULTS: Relative left ventricular weight was elevated and body weight was decreased in D, AS+D and AS+D+C rats (P<.05 vs. CON). Diabetes elevated cardiomyocyte widths, perivascular/interstitial fibrosis (P<.01 each), as well as ECMPs: collagen I/fibronectin/laminin were 3.4-fold/4.1-fold/1.5-fold elevated in D rats and further increased (4.6-fold/5.9-fold/1.9-fold) in AS+D rats (P<.01 vs. CON). Heart rate and blood pressure decreased in D and AS+D rats (P<.05 vs. CON). Carvedilol application attenuated the overexpression of ECMPs. CONCLUSIONS: Beta-adrenoceptor blockade results in regression of the hypertrophic phenotype and in decrease of ECMP in rats with experimental diabetes and in animals with combined chronic pressure overload and hyperglycemia. These results represent a new mechanism of carvedilol that may contribute to the observed beneficial effects in heart failure.

Adrenergic beta-Antagonists↗
PubMed1989

Platelet-derived growth factor enhances deoxyribonucleic acid and collagen synthesis in osteoblast-enriched cultures from fetal rat parietal bone.

Platelet-derived growth factor (PDGF) or closely related proteins are found in bone matrix and are produced by cultured osteosarcoma cells. In serum-deprived osteoblast-enriched (ob) cultures from fetal rat bone, recombinant human PDGF (composed of a B chain homodimer) at 0.1-3 nM enhanced the rate of DNA synthesis by 2- to 8-fold within 24 h of treatment, and 0.3-3 nM PDGF increased cell number by 1.3- to 1.6-fold. Unlike results with rat kidney fibroblast cultures, the mitogenic effect of PDGF in ob cultures was not synergistic with that of insulin-like growth factor I. PDGF at 0.3-10 nM also enhanced the rates of collagen and noncollagen protein synthesis in ob cultures by 1.5- to 4.0-fold, and these increases were blocked when DNA synthesis was prevented. The stimulatory effects of PDGF did not appear specific to ob cultures from fetal rat bone, since similar increases were found in bone cell cultures containing fibroblasts and osteoblast precursors. PDGF binding at 4 C to ob cultures indicated a single class of receptors with a Kd of 0.16 nM and approximately 60,000 sites/cell. Polyacrylamide gel of 125I-PDGF bound and cross-linked to ob cultures revealed a single radioactive band at approximately 180,000-190,000 mol wt. The present studies, therefore, indicate that PDGF can directly increase replication and matrix protein synthesis by both differentiated and undifferentiated bone cells, and that bone- or platelet-derived PDGF may have an important anabolic role in bone remodeling or fracture repair.

Animals↗
PubMed2005

Heart failure after long-term supravalvular aortic constriction in rats.

BACKGROUND: Pressure overload in humans follows a chronic and progressive course, often resulting in eventual cardiac decompensation and death. Animal models of heart failure generally fail to mimic the temporal features observed in human disease often covering a major portion of the life span, and findings of short-term studies are of uncertain applicability. The purpose was to determine whether chronic pressure overload introduced gradually in young normotensive rats would lead predictably to heart failure and to characterize specific phenotype features that have been well documented in another model of heart failure. METHODS: Rats underwent banding of the ascending aorta at 7 weeks of age such that the hemodynamic load increased gradually with ontogenic growth. Two groups of hypertrophied hearts from aortic-banded rats, with and without signs of heart failure, were compared with those of control rats at a mean age of 11 months. RESULTS: Hearts of aorta-banded rats underwent a transition from stable compensated hypertrophy to heart failure that was characterized by augmented hypertrophy, depressed contractile function, elevated fibrosis, increased myocardial stiffness, and marked alterations in the expression of genes encoding contractile, regulatory, and extracellular matrix proteins. CONCLUSIONS: Gradual constriction of the rat aorta resulted in heart failure after a variable length of time (3 to 18 months). Despite differences in genotype, the ultimate phenotype associated with the transition to failure in the aorta-banded rat is nearly identical to that observed in the aged spontaneously hypertensive rat (SHR), with a few notable differences. The findings suggest that a common heart failure phenotype follows long-term pressure overload regardless of the underlying etiology.

Animals↗
PubMed2000

The nu(1) and nu(3) Bands of the (17)O(16)O(17)O Isotopomer of Ozone.

Using 0.002 cm(-1) resolution Fourier transform absorption spectra of an (17)O-enriched ozone sample, an extensive analysis of the nu(3) band together with a partial identification of the nu(1) band of the (17)O(16)O(17)O isotopomer of ozone has been performed for the first time. As for other C(2v)-type ozone isotopomers [J.-M. Flaud and R. Bacis, Spectrochim. Acta, Part A 54, 3-16 (1998)], the (001) rotational levels are involved in a Coriolis-type resonance with the levels of the (100) vibrational state. The experimental rotational levels of the (001) and (100) vibrational states have been satisfactorily reproduced using a Hamiltonian matrix which takes into account the observed rovibrational resonances. In this way precise vibrational energies and rotational and coupling constants were deduced and the following band centers nu(0)(nu(3)) = 1030.0946 cm(-1) and nu(0)(nu(1)) = 1086.7490 cm(-1) were obtained for the nu(3) and nu(1) bands, respectively. Copyright 2000 Academic Press.

Journal Article↗
PubMed2003

Spectroelectrochemical studies on mixed-valence states in a cyanide-bridged molecular square, [Ru(II)(2)Fe(II)(2)(mu-CN)(4)(bpy)(8)](PF6)(4).CHCl(3).H(2)O.

A cyanide-bridged molecular square of [Ru(II) (2)Fe(II) (2)(mu-CN)(4)(bpy)(8)](PF(6))(4).CHCl(3).H(2)O, abbreviated as [Ru(II) (2)Fe(II) (2)](PF(6))(4), has been synthesised and electrochemically generated mixed-valence states have been studied by spectroelectrochemical methods. The complex cation of [Ru(II) (2)Fe(II) (2)](4+) is nearly a square and is composed of alternate Ru(II) and Fe(II) ions bridged by four cyanide ions. The cyclic voltammogram (CV) of [Ru(II) (2)Fe(II) (2)](PF(6))(4) in acetonitrile showed four quasireversible waves at 0.69, 0.94, 1.42 and 1.70 V (vs. SSCE), which correspond to the four one-electron redox processes of [Ru(II) (2)Fe(II) (2)](4+) right arrow over left arrow [Ru(II) (2)Fe(II)Fe(III)] (5+) right arrow over left arrow [Ru(II) (2)Fe(III) (2)](6+) right arrow over left arrow [Ru(II)Ru(III)Fe(III) (2)](7+) right arrow over left arrow [Ru(III) (2)Fe(III) (2)](8+). Electrochemically generated [Ru(II) (2)Fe(II)Fe(III)](5+) and [Ru(II) (2)Fe(III) (2)](6+) showed new absorption bands at 2350 nm (epsilon =5500 M(-1) cm(-1)) and 1560 nm (epsilon =10 500 M(-1) cm(-1)), respectively, which were assigned to the intramolecular IT (intervalence transfer) bands from Fe(II) to Fe(III) and from Ru(II) to Fe(III) ions, respectively. The electronic interaction matrix elements (H(AB)) and the degrees of electronic delocalisation (alpha(2)) were estimated to be 1090 cm(-1) and 0.065 for the [Ru(II) (2)Fe(II)Fe(III) (2)](5+) state and 1990 cm(-1) and 0.065 for the [Ru(II) (2)Fe(III) (2)](6+) states.

Journal Article↗
PubMed2004

Infrared cavity ringdown spectroscopy of jet-cooled polycyclic aromatic hydrocarbons.

Infrared absorption spectra of the CH stretching region were observed for naphthalene, anthracene, phenanthrene, pyrene, and perylene using a heated, supersonic, slit-jet source and cavity ringdown spectroscopy. Band positions and intensities recorded with 0.2-cm-1 resolution were compared with previous gas-phase and argon matrix isolation experiments, as well as theoretical calculations. The largest matrix shift in the absorption maximum (-7.4 cm-1) was observed for anthracene, with all others shifted by 3.0 cm-1 or less. Spectral features in the supersonic jet spectrum were generally narrower than those observed in the Ar matrix, with the largest matrix broadening found for the perylene (80% increase). Low number densities observed for the larger polycyclic aromatic hydrocarbons (PAHs) suggest that the lower vapor pressure of PAHs with catacondensed four-membered rings and with five-membered rings other than perylene will not be detectable using our current configuration.

Journal Article↗
PubMed2002

High-sensitivity analyses of metabolites in biological samples by capillary electrophoresis using dynamic pH junction-sweeping.

Emerging fields of biochemical research, such as metabolomics, present challenges to current separation technologies because of the large number of metabolites present in a cell and their often low (submicromolar) concentration. Although capillary electrophoresis (CE) holds great promise as the method of choice for high-resolution separations of biological samples, it suffers from poor concentration sensitivity, especially with the use of UV detection. In CE, sweeping and dynamic pH junction represent two complementary on-line focusing techniques that have been used for sensitivity enhancement of hydrophobic and weakly acidic analytes, respectively. However, the application of either the sweeping or dynamic pH junction technique alone might, in some cases, be less effective for the analysis of certain sample mixtures. Recent work in the development of a hyphenated dynamic pH junction-sweeping technique is presented as an effective on-line method of preconcentration suitable for both hydrophilic (anionic) and hydrophobic (neutral) analytes. Sensitive analyses of flavin metabolites by CE with laser-induced fluorescence (LIF) detection is demonstrated in various biological matrixes, including cell extracts of Bacillus subtilis, pooled human plasma, as well as heat-deproteinized flavoenzymes. Enhanced analyte band narrowing and improved sensitivity is achieved for flavins using dynamic pH junction-sweeping compared to either sweeping or dynamic pH junction alone. This results in over a 1200-fold improvement in sensitivity relative to conventional injection methods, giving a limit of detection (LOD, defined as S/N = 3) of about 4.0 x 10(-12) M. Strategies for sensitive and more comprehensive analyses of other cell metabolites, including nucleotides, coenzymes, and steroids, are also discussed when using on-line focusing techniques in conjunction with multiplexed CE and UV detection.

Bacillus subtilis↗
PubMed1998

Purification, properties, and multiple forms of a manganese-activated inorganic pyrophosphatase from Bacillus subtilis.

The hydrolysis of magnesium pyrophosphate by inorganic pyrophosphatase from Bacillus subtilis required its specific, time-dependent, and prior activation by Mn2+ ions. This was reversed when Mn2+ ions were removed with EDTA. Free Mn2+ ions were not required for catalysis. Pyrophosphatase purified to near homogeneity gave a single main band of apparent M(r) 36,000 by SDS-PAGE, but of M(r) 34,000 by matrix-assisted laser desorption ionization-mass spectrometry. The native enzyme equilibrated at pH 7 between three distinct molecular forms. Exposure to Mn2+ generated a catalytically active trimer of specific activity about 5000 mumol pyrophosphate hydrolyzed/min/mg protein. Exposure to EDTA generated two catalytically inactive forms, a dimer at low ionic strength and a separate form, of uncharacterized multimeric nature, at molar concentrations of Na2SO4 or Li2SO4. The latter form was an intermediate in the dimer-trimer transition caused by addition or removal of manganese ions. Mn2+ reacted with this "intermediate" form, apparently by reversible association with two noninteracting binding sites of Kd approximately 0.005 and 0.35 microM, respectively. The properties of this enzyme may account in part for the unusual manganese requirements of B. subtilis and related species.

Bacillus subtilis↗
PubMed2002

The purification of polyphenol oxidase from tobacco.

A new polyphenol oxidase (PPO) named PPO II was purified from tobacco (Nicotiana tobacum) by using acetone powder, ammonium sulfate precipitation, and column chromatography on DEAE-Sephadex A-50, Sephadex G-75, and CM-Sephadex C-50. It has an active site of a pair of type 3 coppers bridged to phenolate oxygen, which represents a new catalytic mechanism for polyphenol oxidase. PAGE, SDS-PAGE, and matrix-assisted laser desorption/ionization-time of flight mass spectrometry of the purified enzyme demonstrated that the enzyme is a single band with a molecular mass 35,600 Da. Biochemical characteristics include the optimum pH at 6.0, optimum temperature at 40 degrees C, and K(m) of 1.2 mM for catechol as substrate (pH 6.5, 30 degrees C). Substrate specificity studies indicate that the enzyme is of the catechol oxidase family. PPO II inhibits cultures of Escherichia coli and it accumulates on the wounded sites of tobacco leaves indicating that it may act as a defense role in plant defense systems.

Catechol Oxidase↗
PubMed1982

Principal component analysis of pain-related cerebral potentials to mechanical and electrical stimulation in man.

Single trial event-related cerebral potentials (ERPs) in response to skin stimuli of various intensities and qualities in man were investigated in respect to their nociceptive information content. Electrical constant current stimuli (20 msec, 2 - 8 mA) and mechanical force controlled stimuli (20 msec, 0.8 - 3.2 N) were applied to the tip of the left middle finger. Four intensities of each stimulus quality were given, each intensity appearing 40 times in standardized randomized order. EEG segments (between 5 sec before and 500 msec after stimulus onset) were subjected to computer analysis. ERP wave form was shown to depend upon the amount of alpha waves in the prestimulus EEG. For analysis, only subjects with low power in the alpha band were selected. Principal component analysis was applied to all single trial ERPs measured using the variance-covariance matrix of association. Six principal components (PCs) were extracted accounting for about 90% of total variance. Five of the extracted PCs had well located loading maxima: PC1 (50 - 80 msec), PC4 (140 - 160 msec), PC3 (200 - 250 msec), PC4 (280 - 360 msec), PC5 (400 - 500 msec); PC6 appeared polyphasic. Analysis of variance of the mean PC scores revealed that one PC (PC1) discriminated between quality, and 4 PCs (PC1 - PC4) between quantity of stimulation. Eliminating effects of stimulus intensity resulted in two PCs (PC2, PC4) which distinguished exclusively between non-pain and pain. PCA applied to disjunctive subsets of ERPs, corresponding to the different experimental conditions, yielded practically identical sets of PCs, such that no specific ERP component emerged when pain was reported.

Adult↗
PubMed1990

Mapping of the thrombospondin gene to human chromosome 15 and mouse chromosome 2 by in situ hybridization.

We have mapped the thrombospondin gene (THBS1) to a single locus on human chromosome 15 (band q15) and on mouse chromosome 2 (region F). Thrombospondin has been implicated in a variety of cell-matrix and cell-cell interactions. The finding of a single locus suggests that the different functions of thrombospondin are not due to a closely related family of genes. These results also confirm a region of homology between the proximal part of human chromosome 15 and region F of mouse chromosome 2.

Animals↗
PubMed2005

Metallothionein transfers zinc to mitochondrial aconitase through a direct interaction in mouse hearts.

Previous studies have shown that in a cell-free system, metallothionein (MT) releases zinc when the environment becomes oxidized and the released zinc is transferred to a zinc-binding protein if such a protein is present. However, it is unknown whether and how zinc transfers from MT to other proteins in vivo. The present study was undertaken to test the hypothesis that if zinc transfer from MT to other proteins occurs in vivo, the transfer would proceed through a direct interaction between MT and a specific group of proteins. The heart extract obtained from MT-null mice was incubated with 65Zn-MT or 65ZnCl2 and the proteins receiving 65Zn were separated by blue-native PAGE (BN-PAGE) or sodium dodecyl sulfate-PAGE (SDS-PAGE), and detected by autoradiography. A unique 65Zn-binding band was observed from the 65Zn-MT-incubated, but not the 65ZnCl2-incubated preparation. The analysis using matrix assisted laser desorption/ionization-time-of-flight (MALDI-TOF) mass spectrometry revealed that mitochondrial aconitase (m-aconitase) was among the proteins accepting Zn directly from Zn-MT. The m-aconitase, not the cytosolic aconitase (c-aconitase), was co-immunoprecipitated with MT. This study demonstrates that MT transfers zinc to m-aconitase through a direct interaction.

Aconitate Hydratase↗
PubMed2006

The effect of collagen reinforcement in the behaviour of the temporomandibular joint disc.

In this paper, the influence of collagen fibres in the behaviour of the temporomandibular joint disc is studied. A three-dimensional finite element model of the joint is developed from a set of medical images. The model comprises the mandible, part of the cranium and both temporomandibular joints. Joints have been considered to be composed of the articular discs and the temporomandibular ligaments. A fibre-reinforced porohyperelastic model was used to study the response under clenching of the fibrocartilage that composes the articular disc. This was divided in an intermediate zone, and two bands, an anterior and other posterior, in order to define the orientation of collagen fibres. The study demonstrates that the introduction of collagen fibres in the biphasic behaviour of the articular disc implies for a prescribed displacement not only an increase of the pressurization in the tissue, but also higher stresses in the anterior and posterior bands, as well as in the lateral zone of the disc. Thus, modelling the disc as an isotropic solid matrix leads in this case to an overestimation of the stresses in the intermediate zone, an underestimation of the pore pressure in this area, and an underestimation of the stresses in the rest of the disc.

Aged↗
PubMed2005

Optical poling effect and optical absorption of cyan, ethylcarboxyl and tert-buthyl derivatives of 1H-pyrazolo[3,4-b]quinoline: experiment and quantum-chemical simulations.

We present here results of experimental studies and quantum-chemical simulations of optical absorption and optical poling effects performed on a new synthesized cyan, ethylcarboxyl and tert-buthyl derivatives of 1H-pyrazolo[3,4-b]quinoline incorporated into polymer matrix or dissolved in organic solutions. The efficiency of second-order optical susceptibility d vs photoinduced power density I(p) clearly saturates to certain magnitude d(eff) at sufficient power densities (I(p) > or = 1.3 GW cm(-2)). Comparing experimental data and results of semiempirical quantum-chemical simulations one can conclude that there exists generally a good correlation between the magnitude of saturated susceptibilities d(eff) and macroscopic hyperpolarizabilities for all compounds except the chromophore 1,3-dimethyl-6-cyano-[PQ] only. The discrepancy for this compound may reflect a specific contribution of surrounding polymer matrix. According to the quantum chemical analysis the methyl-containing cyan and ethylocarcoxyl derivatives reveal four/five strong absorption bands in the spectral range 200-500 nm. A substitution of the methyl groups by the phenyl group causes the substantial changes of the absorption spectra mainly in the spectral range 240-370 nm. Measured and calculated absorption spectra manifest rather good agreement mainly in the part regarding the spectral positions of the first oscillator (absorption threshold). The quantum-chemical PM3 method shows the best agreement with experiment. At the same time a considerable broadening almost of all absorption bands appears as a characteristic feature of all measured spectra. The discrepancies between the calculated and the measured spectra are attributed to electron-vibronic coupling as well as to a specific rotational dynamics of phenyl rings.

Absorption↗
PubMed2001

Magnetic resonance of a dextran-coated magnetic fluid intravenously administered in mice.

Magnetic resonance was used to investigate the kinetic disposition of magnetite nanoparticles (9.4 nm core diameter) from the blood circulation after intravenous injection of magnetite-based dextran-coated magnetic fluid in female Swiss mice. In the first 60 min the time-decay of the nanoparticle concentration in the blood circulation follows the one-exponential (one-compartment) model with a half-life of (6.9 +/- 0.7) min. The X-band spectra show a broad single line at g approximately 2, typical of nanomagnetic particles suspended in a nonmagnetic matrix. The resonance field shifts toward higher values as the particle concentration reduces, following two distinct regimes. At the higher concentration regime (above 10(14) cm(-3)) the particle-particle interaction responds for the nonlinear behavior, while at the lower concentration regime (below 10(14) cm(-3)) the particle-particle interaction is ruled out and the system recovers the linearity due to the demagnetizing field effect alone.

Animals↗
PubMed1997

Basement-membrane stromal relationships: interactions between collagen fibrils and the lamina densa.

Collagens, the most abundant molecules in the extracellular space, predominantly form either fibrillar or sheet-like structures-the two major supramolecular conformations that maintain tissue integrity. In connective tissues, other than cartilage, collagen fibrils are mainly composed of collagens I, III, and V at different molecular ratios, exhibiting a D-periodic banding pattern, with diameters ranging from 30 to 150 nm, that can form a coarse network in the extracellular matrix in comparison with a fine meshwork of lamina densa. The lamina densa represents a stable sheet-like meshwork composed of collagen IV, laminin, nidogen, and perlecan compartmentalizing tissue from one another. We hypothesize that the interactions between collagen fibrils and the lamina densa are crucial for maintaining tissue-tissue interactions. A detailed analysis of these interactions forms the basis of this review article. Here, we demonstrate that there is a direct connection between collagen fibrils and the lamina densa and propose that collagen V may play a crucial role in this connection. Collagen V might also be involved in regulation of collagen fibril diameter and anchoring of epithelia to underlying connective tissues.

Animals↗
PubMed2006

Function of membrane protein in silica nanopores: incorporation of photosynthetic light-harvesting protein LH2 into FSM.

A high amount of functional membrane protein complex was introduced into a folded-sheet silica mesoporous material (FSM) that has nanometer-size pores of honeycomb-like hexagonal cylindrical structure inside. The photosynthetic light-harvesting complex LH2, which is a typical membrane protein, has a cylindrical structure of 7.3 nm diameter and contains 27 bacteriochlorophyll a and nine carotenoid molecules. The complex captures light energy in the anoxygenic thermophilic purple photosynthetic bacterium Thermochromatium tepidum. The amount of LH2 adsorbed to FSM was determined optically and by the adsorption isotherms of N2. The FSM compounds with internal pore diameters of 7.9 and 2.7 nm adsorbed LH2 at 1.11 and 0.24 mg/mg FSM, respectively, suggesting the high specific affinity of LH2 to the interior of the hydrophobic nanopores with a diameter of 7.9 nm. The LH2 adsorbed to FSM showed almost intact absorption bands of bacteriochlorophylls, and was fully active in the capture and transfer of excitation energy. The LH2 complex inside the FSM showed increased heat stability of the exciton-type absorption band of bacteriochlorophylls (B850), suggesting higher circular symmetry. The environment inside the hydrophobic silica nanopores can be a new matrix for the membrane proteins to reveal their functions. The silica-membrane protein adduct will be useful for the construction of new probes and reaction systems.

Adsorption↗