Search PubMed⌕ Search

Biomedical subjects

B Starcher

Publications and source records attributed to B Starcher.

At least 37 records · Page 2Linked to original sources
PubMed1995

Increased elastin production in experimental granulomatous lung disease.

In the normal, healthy lung, elastin production is restricted to periods of development and growth. However, elastin expression in the adult lung has been observed in some forms of pulmonary injury, including pulmonary fibrosis. Here, we report that elastin production is significantly increased within precise interstitial compartments of the lung in an experimental model of granulomatous lung disease. An increase in the number and volume of elastic fibers within the alveolar walls was apparent on histological examination of Verhoeff-van Gieson-stained sections of silicotic rat lungs. Quantitation of mature elastin cross-links indicated that silicosis was accompanied by a 17-fold increase in lung elastin content when compared with values from saline-treated controls. In situ hybridization for tropoelastin mRNA revealed that elastin production was absent from granulomatous lesions yet was prominent at nonfibrotic alveolar septal tips, where a high density of elastic fibers is seen in the normal lung. Immunohistochemistry indicated tropoelastin was being expressed by alpha-smooth muscle actin-containing cells. Transforming growth factor-beta was immunolocalized to granulomatous regions of the silicotic lung but was absent from regions showing increased tropoelastin expression. These data indicate that the reinitiation of tropoelastin gene expression is associated with granulomatous lung disease, and this expression leads to the aberrant accumulation of mature elastin in the lung.

Actins↗
PubMed1995

A role for neutrophil elastase in solar elastosis.

Hairless (SKH-1) mice were mated with beige (C57BL/bb) mice to produce a hairless mouse deficient in neutrophil elastase (hhbb). These mice were exposed to 0.09 J UVB radiation for 5 months to see if neutrophil elastase was an important factor in the development of solar elastosis. Analysis of peritoneal neutrophils confirmed that the hhbb mouse was deficient in elastase, retaining only 10% of the activity of the normal littermates (hhHb). Skin myeloperoxidase activity was equally elevated in all the mice receiving UVB indicating a similar influx of inflammatory cells. The absolute breaking strength of the skin in both the hhBb and hhbb mice was not altered by UVB treatment over the 5 month exposure period. Elastin quantitated biochemically as desmosine, or visualized histologically, was increased following UVB exposure in the normal mice. In the elastase-deficient mice, however, the elastin fibres appeared to be unaffected by exposure to UVB radiation at this level. The results suggest that neutrophil elastase is an important mediator in the development of solar elastosis resulting from continued exposure to UVB.

Animals↗
PubMed1992

Fractionation of urine to allow desmosine analysis by radioimmunoassay.

The present study was designed to re-evaluate the radioimmunoassay for desmosine in urine, which is currently used as a measure of elastin metabolism. Using ion exchange chromatography, gel filtration and affinity chromatography it was shown that at least five other compounds in hydrolysates of human urine competed for desmosine in the RIA. Fractionating the urine prior to hydrolysis with acetone removed one of the major contaminants. The other contaminants could subsequently be removed by extracting the urine hydrolysate with a mixture of chloroform/ethanol (60:40). Samples from nine normal adult urines showed that an average of 45% of the RIA competing material in unfractionated urine was not desmosine. The final extracted residue retained all of the desmosine and only 16% of the original solids. The average adult urine contains approximately 50 pmol desmosine/mg creatinine, reflecting a daily turnover of between 3 and 4 mg of elastin per day.

Chemical Fractionation↗
PubMed1991

Neutral metalloendopeptidase associated with the smooth muscle cells of pregnant rat uterus.

The pregnant rat uterus contains a membrane-bound metalloendopeptidase that is biochemically and immunologically similar to kidney enkephalinase (E.C.3.4.24.11). The uterus enzyme readily cleaved specific neutral endopeptidase substrates and oxytocin as well as the synthetic elastase substrate, Suc(Ala)3-pNA, yet did not digest native elastin. Using specific inhibitors, the uterus endopeptidase was identified as a metallopeptidase and not a serine protease, having an absolute requirement for zinc and perhaps calcium for maximal activity. The uterus endopeptidase cross-reacted with polyclonal antiserum to kidney microvillar endopeptidase and a monoclonal antibody to common acute lymphocytic leukemia antigen. Immunohistochemical localization of the enzyme in a 17 day pregnant uterus indicated that the enzyme was localized on the smooth muscle bundles of the myometrium and the endometrial epithelium. Total enzyme activity was 25 times higher in the late-term pregnant uterus (17th day of pregnancy) than in the nonpregnant uterus. Enzyme levels dropped rapidly prior to parturition and within 4 days after delivery the enzyme activity had returned to control levels. Inhibition of NEP in uterine strips with phosphoramidon resulted in a marked potentiation of oxytocin-induced contractions. Our results suggest that the uterine endopeptidase may have an important role in regulating uterine smooth muscle cell contraction during the later stages of pregnancy through its action on oxytocin and perhaps other biologically active peptides.

Animals↗
PubMed1991

A controlled trial of colchicine to reduce the elastase load in the lungs of ex-cigarette smokers with chronic obstructive pulmonary disease.

A great deal of experimental evidence suggests that emphysema in smokers is caused by the action of neutrophil elastase on lung elastin. In order to test this hypothesis, it is necessary to find a drug that reduces the load of neutrophil elastase in the lungs of patients with emphysema. In a previous study we treated smokers with emphysema with colchicine, a drug that prevents neutrophil elastase secretion, to determine if it would reduce the elastase burden in the lungs. Colchicine was unable to reduce the elastase load while the stimulus of smoking continued. In this study we treated ex-smokers with emphysema to determine if colchicine could reduce the elastase burden in the lungs. The objective of the study was to determine if colchicine can reduce the elastase load and putative indicators of elastase load in the lungs of patients with chronic obstructive pulmonary disease. The study was a prospective, double-blind, randomized, and placebo-controlled clinical trial. The subjects were outpatients seeking treatment at the University of Texas Health Center at Tyler. We studied 16 ex-cigarette smokers between 45 and 75 yr of age with lung disease defined by FEV1 less than 70% of predicted but greater than 1.2 L whose airflow obstruction was less than 20% reversible with bronchodilators. Colchicine or placebo was taken by mouth in disguised capsules, 0.6 mg three times per day. Volunteers were placed on a baseline bronchodilator regimen of theodur by mouth and albuterol by inhalation. Blood, urine, and bronchoalveolar lavage fluids were obtained after 1 wk of stabilization.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1991

Evidence that genetic emphysema in tight-skin mice is not caused by neutrophil elastase.

Mutant tight-skin mice that had severe pulmonary emphysema were crossed with beige mice that contained neutrophils deficient in elastase activity. The resultant tight skin-beige cross mice were deficient in neutrophil elastase activity, yet they were still afflicted with the same degree of severe emphysema as the tight-skin mice. The results indicate that neutrophil elastase does not cause the emphysematous lesions found in tight-skin mice.

Animals↗
PubMed1990

A controlled trial of colchicine to reduce the elastase load in the lungs of cigarette smokers with chronic obstructive pulmonary disease.

Current data suggest that emphysema in smokers is caused at least in part by the unrestrained action of neutrophil elastase on pulmonary tissues. Since colchicine reduces the secretion of enzymes from stimulated neutrophils, we designed a clinical trial to determine if colchicine could reduce the elastase load in the lungs or several putative indicators of elastin destruction. We carried out a prospective, double-blind, randomized, and placebo-controlled clinical trial. Outpatients seeking treatment for chronic obstructive pulmonary disease at the University of Texas Health Center at Tyler who met specific criteria were recruited into the study. A group of 46 cigarette smokers between 45 and 75 yr of age with chronic obstructive pulmonary disease (COPD) were studied. Colchicine or placebo was given orally in disguised capsules, 0.6 mg three times per day. Volunteers were placed on a baseline bronchodilator regimen of Theodur orally and albuterol by inhalation. Blood, urine, and bronchoalveolar lavage fluids were obtained after 1 wk of stabilization. The patients were then randomized and treated for 14 days with colchicine, and the measurements were repeated. Modifications in plasma elastin peptides and neutrophil elastase-generated fibrinopeptide A, urinary desmosines, and bronchoalveolar lavage fluid neutrophils or neutrophil elastase were the indicators of success or failure of the treatment. Pre- and posttreatment measurements in each patient and the difference between colchicine-treated and placebo-treated groups were compared. There were no statistically significant differences in either of the two types of analyses in any of the variables. We conclude that variables related to elastase load in the lungs were not modified by colchicine treatment. If a drug can be identified that is successful in modifying one of these variables, it would then have to be tested in a large-scale clinical trial in which the rate of decline in the FEV1.0 or mortality would be measured. The data presented here may provide useful information about the variability of key measurements of elastase load in the lungs and the breakdown of elastin and may aid investigators in designing similar trials in the future.

Aged↗
PubMed1989

Changes in collagen and elastin in rabbit right-ventricular pressure overload.

Collagen content, the ratio of collagen types I and III and elastin content were measured in 5-6- and 10-12-week-old rabbits with and without right-ventricular pressure overload. Significant and equivalent hypertrophy occurred in both age groups. A 2-day pressure overload caused a fall in collagen concentration below control levels in right-ventricular tissue from the older animals, but no change in the younger ones. A 2-week pressure overload in the older animals resulted in a rise in collagen concentration, a decreased ratio of type III to type I plus III [III/(I + III)] collagens, a fall in desmosine concentration and a fall in the desmosine/hydroxyproline ratio in the right ventricle. None of these changes occurred in the younger age group. We hypothesize that the changes in connective-tissue proteins after overload in the older group may contribute to previously observed changes in mechanical performance. The divergent connective-tissue responses in the two groups suggest the importance of age in determining outcome, as well as the possibility of separate regulatory mechanisms for contractile and for architectural elements of the heart.

Animals↗
PubMed1989

A method for intratracheal instillation of endotoxin into the lungs of mice.

A detailed method is presented for the intratracheal instillation of fluids into the lungs of mice. Using 125I-albumen it was determined that 25-50 microliters of volume gave almost equal distribution to all lobes of the mouse lung. Extremely low levels of endotoxin given intratracheally (12.5-25 ng) resulted in a dramatic increase in the neutrophil content of the lung. The increase started in less than 4 h, reaching levels of 7 x 10(5) by 18 h and was maintained at elevated levels for at least 48 h. This neutrophil count represented more than 90% of the cell population of the lung.

Animals↗
PubMed1989

The beige mouse: role of neutrophil elastase in the development of pulmonary emphysema.

Mutant beige mice and normal C57 black mice were given endotoxin intratracheally (IT) once a week for 10 weeks. The objective was to establish whether repeated recruitment of neutrophils to the lung, at levels that induced lung injury to normal mice, would be ineffective in producing lung lesions in neutrophil elastase-deficient beige mice. Endotoxin (25 mg) given IT causes a rapid influx of neutrophils into the lungs of both the C57 black and beige mice, reaching a maximum after 18 h and remaining elevated for at least another 30 h. After 10 weeks of endotoxin instillation the normal C57 black mouse lungs showed evidence of lung injury. There were histological signs of alveolar wall damage, and the mean linear intercepts (Lm) were increased 30% in the endotoxin-treated group. The specific compliance of the lungs from the endotoxin-treated mice was slightly increased. Beige mice, on the other hand, showed no histological or morphological evidence that the neutrophil influx produced lung injury. There was, however, a notable difference in the histological appearance of the control beige lungs compared to control C57 blacks. Beige lungs appeared normal at birth but apparently do not undergo normal alveolarization during neonatal development. Adult lungs have fewer alveoli with smooth terminal air ducts lacking the normal complement of alveolar struts. There was not indication of copper deficiency or problems in elastin synthesis or structure in the beige mice. The results of these studies support a preeminent role for elastase in neutrophil-induced lung lesions.

Aging↗
PubMed1988

Identification of a uterine elastase in the pregnant rat uterus.

During development of the pregnant rat uterus there is a several fold increase in elastin content. Using Verhoeff's elastic fiber stain, we have shown that a significant proportion of these elastin fibers are in the extracellular matrix of the myometrium. They do not appear as an organized structure but rather in a variety of partially extended, random configurations. An elastase was identified in both the pregnant and the postpartum uterus. Partial characterization of the enzyme indicated that it is a serine protease with a molecular weight around 24,500 and a pH optimum of 8.5. In addition to the enzyme, relatively high levels on an elastase inhibitor were found in the uterine extracts. The inhibitor did not inhibit trypsin, indicating that it was not alpha-1-antiprotease. The data suggest that the elastase and inhibitor are uterine tissue derived and perhaps important in the normal remodeling process of uterine connective tissue.

Animals↗
PubMed1987

Isolation and characterization of a pentameric amino acid from elastin.

An unknown amino acid was purified from bovine ligament elastin. The compound was shown by proton NMR to have a pyridinium ring structure similar to isodesmosine, yet containing an olefinic double bond on one additional side chain which was not attached to the pyridinium ring. Mass spectral analysis confirmed the NMR data and indicated a parent compound with a mass of 653. A structure is proposed that is derived from the condensation of five lysine residues. The trivial name of pentasine is proposed for this compound.

Amino Acids↗
PubMed1985

Elastin turnover in the rat uterus.

During pregnancy the rat uterus shows a steady increase in total elastin content, reaching levels of 300% above non-pregnant controls. Elevated levels of urinary desmosine are also seen during this period. After parturition there is a slight lag period and then rapid removal of elastin from the uterus, reaching baseline after five days. Urinary desmosine levels were elevated for about seven days post partum before returning toward control levels. Analysis of pre- and post-partum serum showed no significant differences. The involuting rat uterus appears to be an excellent model for the study of processes involved in elastin catabolism.

Animals↗
PubMed1985

Isolation and characterization of a proteinase inhibitor from marama beans.

A protease inhibitor was purified from the African marama bean (Tylosema esculenturm). The inhibitor is present in large amounts, representing about 10.5% of the total protein. The molecular weight is slightly larger than soybean trypsin inhibitor and was estimated at 23,000 by SDS-gel electrophoresis or 24,500 by amino acid analysis. The amino acid composition was atypical of most other plant inhibitors with a cysteine content of only one or possibly two residues/mole and a blocked amino terminus. Inhibition studies indicated virtually no inhibition of chymotrypsin activity. Elastase, however, was inhibited to the same extent as trypsin, requiring about 2 moles of inhibitor for complete inhibition of the enzyme.

Amino Acids↗
PubMed1981

Elastin synthesis by ligamentum nuchae fibroblasts: effects of culture conditions and extracellular matrix on elastin production.

Fetal bovine ligamentum nuchae fibroblasts maintained in culture synthesized soluble elastin but were unable to form the insoluble elastic fiber. Secreted elastin precursors accumulated in culture medium and were measured using a radioimmunoassay for elastin. When elastin production was examined in ligament tissue from fetal calves of various gestational ages, cells from tissue taken during the last trimester of development produced significantly more elastin than did cells from younger fetal tissue, with maximal elastin synthesis occurring shortly before birth. Soluble elastin was detected in ligament cells plated at low density until proliferation began to be density inhibited and the cells became quiescent. Also, soluble elastin production per cell declined with increasing population doubling or with age in culture. Cells grown in the presence of 5% fetal calf serum produced approximately four times as much soluble elastin as cells grown in serum-free medium. The addition of dexamethasone (0.1 microM) and bleomycin (1 microgram/ml) increased soluble elastin production by cultured cells 180% and 50%, respectively, whereas theophylline (5 micrograms/ml) depressed production 50% and antagonized stimulation by dexamethasone. Ascorbate (50 micrograms/ml), soybean trypsin inhibitor (1 mg/ml), insulin (100 microunits/ml), and aminoacetonitrile (50 micrograms/ml) had no effect, but cycloheximide at 10(-4) M completely inhibited soluble elastin production. In contrast to cells in culture, ligament tissue minces (ligament cells surrounded by in vivo extracellular matrix) efficiently incorporated soluble elastin precursors into insoluble, cross-linked elastin. In addition, soluble elastin production per cell (per microgram of DNA) was higher in tissue minces than elastin production by cells maintained on plastic. These results suggest a role for extracellular matrix in formation of the elastic fiber and in stabilizing elastin phenotypic expression by ligament fibroblasts. Fibroblasts from the bovine ligamentum nuchae present an excellent model for in vitro studies of elastin biosynthesis.

Animals↗