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Biomedical subjects

K R Cutroneo

Publications and source records attributed to K R Cutroneo.

At least 37 records · Page 2Linked to original sources
PubMed1986

Glucocorticoids change the ratio of type III to type I procollagen extracellularly.

Rat skin fibroblasts were treated with dexamethasone and labeled with radioactive proline for 2 hours. Intracellular and extracellular procollagens were immunoprecipitated with monospecific polyclonal antibodies. Both intracellular and extracellular types I and III procollagen were decreased coordinately by glucocorticoid treatment. The ratio of type III to type I procollagen was the same for control and dexamethasone-treated cell cultures. However, when rat skin fibroblasts were prelabeled with radioactive proline and chased in the presence of unlabeled proline the ratio of type III to type I extracellular procollagens remained constant in the glucocorticoid-treated cells and increased in control fibroblasts.

Animals↗
PubMed1986

Skin lysyl oxidase activity is not rate limiting for collagen crosslinking in the glucocorticoid-treated rat.

Lysyl oxidase activity in the skin of rats receiving triamcinolone diacetate (12 mg/kg) for three consecutive days was decreased by sixty-four percent as compared to control values. A decrease of lysyl oxidase activity was observed twelve hours after the initial glucocorticoid injection. The decreased lysyl oxidase activity was accompanied by a forty-nine percent decrease of acetic acid extractable collagen. There was also a forty-two percent decrease in the alpha/beta ratio of the acetic acid soluble skin collagen of glucocorticoid-treated animals. These data indicate that although skin lysyl oxidase activity is decreased by glucocorticoid treatment, the crosslinking of acid extracted collagen as measured by the alpha/beta ratio and collagen solubility is increased. Accordingly lysyl oxidase activity is not rate limiting for collagen crosslink formation in the skins of rats treated with glucocorticoids.

Acetates↗
PubMed1985

Bleomycin selectively elevates mRNA levels for procollagen and fibronectin following acute lung injury.

We employed the technique of dot blot hydridization of radiolabeled cDNA probes to examine the role of specific mRNA content in the control of extracellular matrix turnover in the remodeling rat lung. Following bleomycin instillation, total RNA content gradually doubled during the first 5 days following the initial lung injury, then rose much more rapidly during the ensuing 9 days. Individual mRNAs for procollagens I and III and for fibronectin were selectively enriched 2- to 4-fold above total RNA during the first week after bleomycin instillation. No comparable increases were observed in specific RNAs from liver, indicating that the response observed in the lung was not generalized to other organs. Moreover, the increases in mRNA species for procollagen types I or III in the lung could not be related to the influx of inflammatory cells which migrate into the lungs during acute injury, as cells obtained by alveolar lavage contained no mRNAs for procollagens.

Animals↗
PubMed1985

Collagen accumulation in the neonatal rat skin: absence of fibrillar collagen degradation during normal growth.

Collagen-bound collagenase activity was assayed in the entire skins of growing neonatal rats. The levels of fibrillar collagen degradation were found to be extremely low throughout the first six days of life. Less than one percent of the collagen accumulated during one day's growth could be degraded by the collagenase bound to the extracellular fibrils of the skin. Control experiments, which included the addition of purified rat uterine collagenase to the skins both before and after homogenization, showed that collagenase activity is easily detectable in the tissue when it is present. It therefore appears that the vast majority of skin collagen, once deposited as fibrils in the skin, fails to turn over during growth. Support for this concept was provided by experiments in which neonatal animals were injected with the potent synthetic glucocorticoid, triamcinolone. Very low levels of collagen-bound collagenase, comparable to those observed in control animals, were found in the steroid-treated animals. Furthermore, the inhibition of collagen synthesis in these animals resulted in a constant chemical content of collagen as well as a constant amount of proteinaceous [14C]-hydroxyproline after injection of [14C]-proline over a 72-hour period. Our results strongly suggest that the bulk of fibrillar collagen does not participate in a dynamic equilibrium between synthesis and degradation during normal neonatal growth. In addition, the results in steroid-treated animals suggest that the rate of collagen accumulation during this period appears to be essentially a function only of collagen synthesis.

Animals↗
PubMed1984

Anti-inflammatory adrenal steroids that neither inhibit skin collagen synthesis nor cause dermal atrophy.

Clinically used topical anti-inflammatory adrenal steroids inhibit skin collagen synthesis. This impaired collagen synthesis may result in dermal atrophy. Structure activity studies contrasted the effects of the novel prednisolone derivatives, methylprednisolonate , and methyl 20 dihydroprednisolonate , with presently used anti-inflammatory adrenal steroids on granuloma formation and skin collagen synthesis. These two new prednisolone derivatives, when applied locally at equivalent-potency anti-inflammatory doses compared with other corticosteroids, markedly inhibit granuloma formation but do not inhibit skin collagen synthesis nor cause dermal atrophy in rats. The data indicate that the two prednisolone acid methyl esters may be safer topical anti-inflammatory adrenal steroids to use, since they do not inhibit normal skin collagen synthesis.

Administration, Topical↗
PubMed1983

Bleomycin treatment of chick fibroblasts causes an increase of polysomal type I procollagen mRNAs. Reversal of the bleomycin effect by dexamethasone.

Bleomycin treatment of primary chick skin fibroblasts and chick lung fibroblasts resulted in a selective dose-dependent increase of cell layer procollagen synthesis. Solid support hybridization of total cellular RNA to 32P-labeled pro-alpha 1(I) and pro-alpha 2(I) cDNAs did not indicate an increase of total cellular procollagen type I mRNAs in bleomycin-treated cells. However, bleomycin treatment of chick skin fibroblasts causes a redistribution of procollagen type I mRNAs within the nuclear, cytoplasmic, and polysomal subcellular fractions. Both the nuclear and cytoplasmic procollagen type I mRNAs are significantly decreased in concentration after bleomycin administration. In contrast, the polysomal procollagen type I mRNAs are significantly increased in both chick skin and lung fibroblasts treated with bleomycin. Administration of dexamethasone to bleomycin-treated fibroblasts resulted in a reversal of the bleomycin-induced increase in cell layer procollagen synthesis. The increased amounts of polysomal procollagen type I mRNAs in bleomycin-treated cells were also reduced by subsequent administration of dexamethasone. These data indicate that bleomycin treatment of chick skin and chick lung fibroblasts results in a specific increase in procollagen synthesis in the cell layer which is mediated by elevated levels of polysomal type I procollagen mRNAs via a repartitioning of these mRNAs within the fibroblast. Furthermore, dexamethasone reverses the bleomycin-induced elevations of both cell layer procollagen synthesis and polysomal type I procollagen mRNAs.

Animals↗
PubMed1983

Dexamethasone decreases the amounts of type I procollagen mRNAs in vivo and in fibroblast cell cultures.

Dexamethasone treatment of neonatal chicks resulted in a time- and dose-dependent selective decrease of skin collagen synthesis. Total RNA of chick skin was isolated and hybridized to the cloned cDNAs pCg54 for pro-alpha 1 (I) mRNA and pCg45 for pro-alpha 2(I) mRNA. RNA isolated from the total skin of chicks receiving various doses of dexamethasone had dose-related decreases of pro-alpha 1 (I) and pro-alpha 2(I) mRNAs. The decrease of type I procollagen mRNAs for various doses of dexamethasone were similar to the decreases observed for collagen synthesis in vivo. Dexamethasone treatment of chick skin and chick lung fibroblasts resulted in a selective decrease of procollagen synthesis. A dose-related decrease of procollagen synthesis was observed with chick skin fibroblasts. Dexamethasone-treated chick skin and chick lung fibroblasts had decreased levels of pro-alpha 1 (I) and pro-alpha 2(I) mRNAs as determined by solid support hybridization with pCg54 and pCg45. The dexamethasone-mediated decreases of type I procollagen mRNAs in skin fibroblasts and lung fibroblasts were similar to the decreases observed in procollagen synthesis.

Animals↗
PubMed1983

Glucocorticoids coordinately regulate procollagens type I and type III synthesis.

Antibodies to type I and type III procollagens were raised in rabbits and were made monospecific by chromatography on collagen and procollagen affinity columns. The antibodies were determined to be monospecific by the direct enzyme-linked immunosorbent assay and the enzyme-linked immunosorbent assay inhibition assay. Rats were treated with various doses of triamcinolone diacetate, pulse-labeled with radioactive proline for 20 min, and the procollagens were precipitated with procollagen antibodies. The degree of inhibition of procollagen type I and type III synthesis to corticosteroid treatment was the same. This coordinate effect of glucocorticoids on the synthesis of the two procollagens was reversible, dose-dependent, time-dependent, and observed in lung as well as in skin. These data indicate that glucocorticoids coordinately regulate the synthesis of type I and type III procollagen in skin and lung to the same extent.

Animals↗
PubMed1983

Lavage type III procollagen N-terminal peptides in human pulmonary fibrosis and sarcoidosis.

Levels of type III procollagen N-terminal peptide were immunoassayed in sera and bronchoalveolar lavage fluids from healthy volunteers and patients with idiopathic pulmonary fibrosis or sarcoidosis. Peptide levels normalized to protein were higher than corresponding serum levels in all groups, suggesting that the lung is a producer of this peptide. Levels were significantly elevated in both patient groups, suggesting increased rates of type III collagen synthesis. Values were highest in idiopathic pulmonary fibrosis samples. Correlation of peptide levels with clinical severity of disease and lavage cell profiles was poor, perhaps because the latter reflects aspects of the disease process other than that stage in which type III collagen synthesis is altered. Lavage analyses of procollagen peptides may provide an important index of altered collagen synthesis in interstitial lung disease.

Amino Acid Sequence↗
PubMed1982

Inhibition of collagen accumulation by glucocorticoids in rat lung after intratracheal bleomycin instillation.

Male Fischer 344 rats were given a single lung instillation of bleomycin sulfate (0.6 units/100 g). some animals were treated 24 hr after bleomycin administration with triamcinolone diacetate. Steroid treatment was continued on alternate days for 4 weeks. At the end of 4 weeks, the lungs of rats receiving bleomycin alone had two-fold increases of both prolyl hydroxylase activity and proteinaceous hydroxyproline as compared to control values. The lungs of bleomycin-treated rats which received 4 mg of triamcinolone diacetate per kg on alternate days had a 33% increase of prolyl hydroxylase activity and proteinaceous hydroxyproline content of bleomycin-treated animals receiving glucocorticoid (8 mg/kg) on alternate days were the same as control values. The results indicate that alternate day administration of the synthetic glucocorticoid triamcinolone diacetate blocks lung collagen accumulation following a single intratracheal dose of bleomycin to rats.

Animals↗
PubMed1982

Bleomycin-induced increase of collagen turnover in IMR-90 fibroblasts: an in vitro model of connective tissue restructuring during lung fibrosis.

Late-log-phase IMR-90 human fetal lung fibroblasts were incubated with bleomycin sulfate for 48 hr. The culture medium was removed and replaced with serum-free medium and [5-3H]proline. The cells were then incubated for increasing time intervals. The cells and culture medium were collected, and radioactive proline incorporated into collagen and noncollagen protein was determined. Intracellular collagen synthesis was selectively increased. Furthermore, polysomes isolated from bleomycin-treated cells synthesized significantly more collagen in the wheat germ lysate than did control polysomes. Prolyl hydroxylase activity was also increased significantly in the bleomycin-treated cells. Free and peptide-bound radioactive hydroxyproline in the cells and medium was greatly increased in bleomycin-treated cells, which indicates increased collagen degradation. The results demonstrate that, although collagen synthesis in lung fibroblasts is increased by bleomycin, the newly synthesized collagen is rapidly degraded in both the cell layer and the medium. This increased collagen degradation may be responsible for the remodeling which takes place during lung fibrosis.

Bleomycin↗