Search PubMed⌕ Search

Biomedical subjects

E Fujimori

Publications and source records attributed to E Fujimori.

At least 37 records · Page 2Linked to original sources
PubMed1985

Changes induced by ozone and ultraviolet light in type I collagen. Bovine Achilles tendon collagen versus rat tail tendon collagen.

High-molecular-mass aggregates were made soluble from insoluble collagens of bovine Achilles tendon and rat tail tendon by limited thermal hydrolysis. These polymeric collagen aggregates were cross-linked by 390-nm-fluorescent 3-hydroxy-pyridinium residues (excited at 325 nm) in the former tendon and by unknown non-fluorescent residues in the latter. With the solubilized insoluble-collagens from both tendons, as well as with acid-soluble collagen from rat tail tendon, other 350-385-nm fluorescence intensities (excited at 300 nm) were found to be higher in monomeric chains than in dimeric and polymeric chains. Low levels of ozone inhibited fibril formation of acid-soluble collagen particularly from young rat tail tendon, reacting with tyrosine residues and the 350-385-nm fluorophores. Aldehyde groups, involved in cross-linking, were not effectively modified by ozone. beta-Components (alpha-chain dimers) were not efficiently dissociated even by higher doses of ozone compared to gamma-components (alpha-chain trimers). Polymeric chain aggregates from bovine Achilles tendon collagen, whose 3-hydroxy-pyridinium cross-links are cleaved by ozone, were more readily dissociated by ozone than those from rat tail tendon collagen. Ultraviolet (300-nm) light, which destroyed the 350-385-nm fluorophores, inhibited fibril formation less effectively than ultraviolet (275-nm) light, which is absorbed by tyrosine residues, and did not dissociate collagen polymers from rat tail tendon. On the other hand, ultraviolet (320-nm) light, absorbed by 3-hydroxy-pyridinium cross-links which were rapidly photolyzed, partially dissociated polymeric collagen aggregates from bovine Achilles tendon after subsequent heating.

Achilles Tendon↗
PubMed1985

Ultraviolet light- and ozone-induced changes in pyridinoline, a trisubstituted 3-hydroxypyridinium crosslink of collagen.

Pyridinoline photo-degraded with the formation of photoproducts absorbing diffusely around 260-290 nm (pH 7) and sharply at 232 nm (pH 1). Subsequent heating partially regenerated the original pyridinoline, also producing new products absorbing at 417/440 nm (pH 7) and 300/412 nm (pH 1). Pyridinoline (pH 7) and its new products (pH 7 and pH 1) also underwent ozone-induced degradation.

Amino Acids↗
PubMed1983

Cross-linking and fluorescence of pyrene-labeled collagen.

The pyrene-labeling of acid-soluble (type I) and acid-insoluble collagens from young and old rat tail tendon has been investigated. The pyrene excimer fluorescence is associated with stabilized pyrene labels bound to two adjacent aldehydes in monomeric young collagens. Polymeric young collagens, as well as monomeric and polymeric old collagens, tend to lose this specific arrangement. This is shown by salt and new chromatographic fractionation of monomeric and polymeric collagens. During denaturation, pyrene labels are released from saturated aldehydes in both alpha 1 and alpha 2 chains. This unstable pyrene-labeling is stabilized by NaBH4 reduction of the hydrazone bonds between aldehyde groups and pyrene-containing hydrazines. This stabilization reveals that alpha 1 contains more aldehyde groups than does alpha 2 in young collagen. Pepsin-solubilized, acid-insoluble collagens are partly cross-linked and, like acid-soluble collagens, exhibit the fluorescence of pyrene aggregates probably located at unidentified cross-links, different from unsaturated aldehyde-containing cross-links in acid-soluble collagens.

Aging↗
PubMed1983

Benzo[a]pyrene-collagen interactions.

In vitro interactions of benzo[a]pyrene (BaP) with acid-soluble type I collagen from rat tail tendon have been investigated. The fluorescence of BaP increases in the presence of collagen. Bound BaP inhibits the formation of collagen fibrils in solution. When BaP-collagen complexes are irradiated in air with UV (365 nm) light, BaP rapidly undergoes photooxidation with the further inhibition of fibril formation. Viscosity and circular dichroism (CD) studies show that neither BaP nor further UV-irradiation alters the size or helical conformation of the protein. During thermal denaturation of collagen, BaP fluorescence changes. Collagen from young rat tail tendon shows a pronounced drop at about 38 degrees C, whereas that from old rat tail tendon exhibits an increase with a plateau in the same temperature range. These anomalous changes are observed when tyrosine residues, present only in the non-helical terminal telopeptides of collagen, are excited at 275 nm, but not by direct BaP excitation at 387 nm. These findings suggest that the specific hydrophobic telopeptide region, which plays an important role in fibril formation, are affected by bound BaP.

Aging↗
PubMed1982

Crosslinking and photoreaction of ozone-oxidized calf-lens alpha-crystallin.

Direct-photo-oxidation, singlet oxygen-oxidation, or photosensitized oxidation can modify lens crystallins, causing an increase in blue fluorescence and covalent crosslinking. A relationship between these changes has not been elucidated. We now report results from experiments with ozone oxidation. When calf-lens alpha-crystallin is treated with zone oxidation. When calf-lens alpha-crystallin is treated with ozone, new absorption, fluorescence, and phosphorescence, which are characteristic of the oxidized product of tryptophan (N-formylkynurenine), appear at 320, 435, and 445 nm, respectively. In addition, in this ozonization of alpha-crystallin, its polypeptides are crosslinked by nondisulfide bonds. Irradiation of ozone-treated alpha-crystallin with near-ultraviolet (365 nm) light increases crosslinking and reduces the 320 nm absorbance with a concomitant appearance of a new absorption at about 420 nm. This photoproduct exhibits an intense fluorescence around 450 nm and a weak phosphorescence at 510 nm, with excitation peaks at 400, 415, and 422 nm. These findings are essentially the same as those observed in photo-oxidized alpha-crystallin, suggesting the involvement of the same tryptophan oxidized product in the modification of the lens protein.

Animals↗
PubMed1981

Fluorescent-labeled cross-links in collagen: pyrenesulfonylhydrazine.

Aldol condensation products of two lysyl-derived aldehyde (allysine) residues are involved in cross-linking of collagen. However, the distribution of these cross-links and their age-related changes remain largely unanswered. We have found that the unsaturated aldehydes of aldol condensation cross-links can be fluorescent labeled. When labeled with pyrenesulfonylhydrazine, pyrene dimers and excimers fluoresce at 383 and 485, nm, respectively. (The pyrene dimer is stable in benzene, whereas in polar solvents it exhibits an exponential decay to monomer fluorescing at 378 nm.) Dimers bound to collagen also decay to monomers, but at a more complicated, nonexponential rate. This dissociation in collagen is also associated with gradual decrease in the excimer fluorescence. While dissociated monomers appear to be reassociated by redialysis, the excimer is not regenerated. During fibril formation in vitro of the labeled collagen, two fluorescence changes take place: a very rapid decrease of the excimer fluorescence and a gradual increase of the monomer fluorescence. These changes indicate very early and early conformational changes at the nonhelical terminal telopeptides. The excimer fluorescence also decreases upon thermal and guanidine denaturation. Two different environments for excimer formation are suggested by the latter. It is concluded that pyrenesulfonylhydrazine offers a unique and sensitive probe for the proximity of aldehyde groups as well as for the mobility and conformation changes of the telopeptides in collagen.

Aging↗
PubMed1979

Benzo[a]pyrene--serum : albumin/cysteine interactions: fluorescence and electron spin resonance studies.

The complex between bovine serum albumin (BSA) and benzo[a]pyrene (BaP) exhibits three different types of fluorescence. The visible fluorescence at 407, 431 and 458 nm is modified by the formation of both hydroxy-BaP derivatives and BaP products strongly bound to the protein. The ultraviolet fluorescence I is characterized by a triple-peaked structural fluorescence with maxima at 340, 357 and 378 nm. Upon addition of mercaptoethanol, this ultraviolet fluorescence decreases. The ultraviolet fluorescence II appears at 380 nm and corresponds to that of pyrene-like products. When irradiated with ultraviolet (365 nm) light, both the ultraviolet fluorescence I and the visible fluorescence decreases. In the interactionsof BaP with BSA, a new radical has also been found in addition to the known 6-oxo-BaP radical. The lyophilized BSA-BaP complex exhibits two broad ESR bands, one of which increases in lipid-free BSA. In the concentrated aqueous solution of the BSA-BaP complex, the ESR signal is converted to a six-line spectrum. The benzene extract, which removes non-covalently bound BaP products, shows an ESR signal similar to that in aqueous solution except for the absence of two lower g-valued lines. When irradiated with ultraviolet (365 nm) light the signal intensity of the new radical species decreases, while that of 6-oxo-BaP increases. Upon addition of of mercaptoethanol, the signal of the new radical also diminishes and is replaced by a single narrow signal. Ths mixture of BaP and cysteine kept at room temperature for one day in the dark produces both a six-line ESR spectrum and a broad ultraviolet fluorescence at 330 nm, which gradually decay in about one week. When BaP and cysteine are mixed at 65 degrees C for several hours, little ultraviolet fluorescence and ESR signal are detected. The results indicate the formation of a BaP radical as an intermediate in the interaction of BaP with BSA and cysteine in the presence of oxygen and suggest the involvement of SH-groups in this interaction.

Benzopyrenes↗
PubMed1978

Blue-fluorescent bovine alpha-crystallin.

Blue-fluorescent alpha-crystallin has been isolated from bovine lenses by gel-filtration on Sephacryl S-200 Superfine. The blue fluorescence of this alpha-crystallin is characterized by fluorescence peaks at about 410 and 435 nm and two excitation peaks at about 350 and 370 nm. This finding suggests the existence of two different blue-fluorescences in bovine alpha-crystallin. Both low molecular weight alpha-crystallin and higher molecular weight alpha-crystallin exhibit similar blue fluorescence. With aging, in the nuclear region of bovine lenses, blue fluorescent low molecular weight alpha-crystallin shifts to non-covalently-linked higher molecular weight aggregates which are also blue-fluorescent.

Aging↗