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Biomedical subjects

C Franzblau

Publications and source records attributed to C Franzblau.

At least 145 records · Page 8Linked to original sources
PubMed1977

Proteolysis of tropoelastin.

The presence of an enzyme associated with tropoelastin is described. The enzyme has a pH optimum between 7 and 9 and trypsin-like specificity. Upon incubation, tropoelastin (72,000 molecular weight) is cleaved into relatively high molecular weight fragments. In addition to the parent molecule, five discrete polypeptide bands are usually observed on SDS gels with molecular weights of approximately 57,000, 45,000, 36,000, 25,000 and 13-14,000.

Aminopropionitrile↗
PubMed1977

The fate of intratracheal 14C-guanidinated pancreatic elastase in hamster lung.

Native pancreatic elastase and guanidinated elastase have similar in vitro and in vivo properties and produce emphysema of similar severity in hamsters. 14C-guanidinated pancreatic elastase (16,000 cpm/0.2 mg) was instilled into the trachea of anesthetized hamsters. Within 24 hours the radiolabel found in the lungs rapidly decreases to 12% of the original 16,000 cpm and to 1% after 96 hours. Most of the radiolabel and elastase activity found in the lungs can be removed by bronchopulmonary lavage up to 48 hours after installation. Although seemingly very small, there is a significant amount of radiolabel (1-2%) which cannot be removed from the lungs by extensive bronchopulmonary lavage.

Animals↗
PubMed1977

Role of crosslinking in fiber formation.

The synthesis of elastin by smooth muscle cells is demostrated by amino acid analyses and the presence of lysine-derived crosslinks. The data reveal that the ratio of allysine to aldol decreases with time in culture. The presence of insoluble elastin correlates well with the presence of the reduced aldol condensate in these cells. If the formation of the desmosines occurs by the condensation of the aldol and dehyrolysinonorleucine, the presence of the latter may be rate-limiting since the cells display little or no dehydrolysinonorleucine. Several peptides containing the desmosine crosslink were purified and partially sequenced. The data indicate that desmosines crosslink two polypeptide chains and that both desmosine and isodesmosine are present in the same primary sequence approximately equally substituted. A possible role for tyrosine in the regulation of desmosine formation is presented.

Aldehydes↗
PubMed1977

Studies on the fate of pancreatic elastase in the hamster lung: 14C-guanidinated elastase.

Intratracheal instillation of pancreatic elastase in hamsters produces emphysema, which progresses for up to one year after the insult. To study this process in more detail, a guanidinated derivative of porcine pancreatic elastase labeled with carbon-14 was prepared that was indistinguishable from unmodified elastase with respect to physicochemical properties and in vitro enzymatic activity. Guanidinated pancreatic elastase exhibits the same emphysema-inducing potency as unmodified pancreatic elastase. Two hours after intratracheal instillation of the [14C] guanidinated elastase, the whole lung retained only 40 per cent of the instilled radioactivity, but after 96 hours one per cent was still present. At 2 hours approximately 90 per cent of the radioactivity in the lungs could be removed by bronchopulmonary lavage, and at 96 hours 28 per cent was removable by this method. More than half of the radiolabeled elastase recovered in the lavage fluid at 2 hours was enzymatically active; enzymatic activity diminished to very small amounts by 96 hours. These data support the concept of the long-term binding of active elastase to lung tissue, a phenomenon that may be involved in the progressive nature of elastase-induced emphysema.

Animals↗
PubMed1976

Incorporation of L-azetidine-2-carboxylic acid into hemoglobin S in sickle erythrocytes in vitro.

L-Azetidine-2-carboxylic acid, the naturally occurring lower homologue of L-proline, is incorporated into hemoglobin S (sickle hemoglobin) in vitro. Sickle erythrocytes from patients with sickle cell anemia incubated with L-[3H] azetidine-2-carboxylate synthesized radiolabeled hemoglobin which when isolated from cell lysates, co-chromatographed with hemoglobin S on DEAE-cellulose columns. The alpha/beta ratio of azetidine carboxylate incorporation into the globin chains of sickle hemoglobin was 0.94, which is consistent with the presence of four proline residues in each polypeptide chain. Incorporation of azetidine carboxylate into hot trichloroacetic acid-insoluble material in sickle erythrocytes indicated that the homologue was present in the polypeptide backbone of the globin chains of sickle hemoglobin. Amino acid analysis of the hot trichloroacetic acid-insoluble material from sickle erythrocytes which had been incubated with radiolabeled azetidine carboxylate indicated that 75% of the radioactivity could be accounted for as intact homologue while 20% of the radioactivity co-chromatographed with alanine. These results suggest that azetidine carboxylate is incorporated unaltered into hemoglobin S in addition to being metabolized to alanine in sickle erythrocytes prior to incorporation into protein. The kinetics of thermal precipitation of hemoglobin S (oxygen ligand) into which radioactive azetidine carboxylate or radioactive proline had been incorporated in vitro is identical. This observation, together with the behavior of hemoglobin S and the globin chains from hemoglobin S containing azetidine carboxylate during ion-exchange chromatography, indicates that homologue replacement of prolyl residues does not significantly alter the overall charge or stability of the hemoglobin S tetramer. Azetidine carboxylate did not inhibit uptake of radiolabeled proline by sickle erythrocytes suggesting that the homologue does not adversely affect amino acid transport in these cells.

Amino Acids↗
PubMed1976

Intrinsic enzyme activity associated with tropoelastin.

The presence of an enzyme(s) associated with purified tropoelastin has been established. Results indicate that the enzyme(s) remains closely associated with the soluble elastin throughout the entire purification procedure suggesting that it is very tightly bound. Enzymatic activity is optimum through the pH range 7-9 (37 degrees C) and can be inhibited by disodium ethylenediaminetetraacetate, N-ethylmaleimide, sulfite, soybean trypsin inhibitor and human alpha-1-antitrypsin. The fragmentation pattern appears to be specific and reproducible.

Amino Acids↗
PubMed1976

The interaction of collagen with alpha1-acid glycoprotein.

The influence of alpha1-acid glycoprotein on the formation of fibrous long spacing fibers of collagen has been investigated. It was observed that addition of the glycoprotein to dialyzed collagen solutions caused a significant decrease in the intensity of the circular dichroic spectrum of collagen. This phenomenon, which displays an optimum with respect to glycoprotein, is consistent with previous observations of fibrous long spacing fiber formation. Changes in viscosity of collagen initially dissolved in acetic acid were monitored during dialysis. It was found that a significant increase in viscosity must occur during dialysis of collagen before fibrous long spacing formation could take place. This increase in viscosity can be related directly to removal of acetic acid from the collagen solution. Removal of all sialyl residues from the alpha1-acid glycoprotein with neuraminidase prevents fibrous long spacing formation while removal of up to 35% of the sialyl residues has no effect on the interaction of glycoprotein with collagen. Amino acid composition and radioactivity studies suggest that 45-55% of the insoluble fibrous long spacing fibers is glycoprotein. In contrast to native collagen fibers, reduced fibrous long spacing fibers do not contain histidinohydroxymerodesmosine or hydroxylysinonorleucine. Instead, they contain significant quantities of allysine aldol and epsilon-hydroxynorleucine.

Amino Acids↗
PubMed1976

The synthesis of connective tissue protein in smooth muscle cells.

The synthesis of elastin by smooth muscle cells was clearly demonstrated by amino acid analyses and the presence of lysine-derived crosslinks. The values obtained were compatible with those found in amorphous elastin isolated from rabbit aortic tissue. Collagen synthesis by these same cells was monitored by the appearance of [14C] hydroxyproline when the cells were grown in the presence of [14C] proline. When the cells were pulsed with [14C] lysine, one could detect [14C] hydroxylysine and [14C] glucosylgalactosylhydroxylysine. Further evidence for the synthesis of elastin and collagen was the finding of radiolabelled epsilon-hydroxynorleucine and the reduced aldol condensate of two residues of allysine after reduction of [14C] lysine pulsed cells with NaBH4.

Animals↗
PubMed1976

In vitro effects of elastase and collagenase on mechanical properties of hamster lungs.

A previous study of hamsters, 21 days after intratracheal treatment with pancreatic elastase, showed development of emphysema, shift of the volume-pressure curve up an to the left, with both air and saline filling, and increase in quasistatic lung compliance. There was also a striking increase in vital capacity and lung volume at transpulmonary pressure of 25 cm H2O (TLC25); however, 21 days after collagenase treatment, there was only a slight increase in TLC25. The lung volume changes were not consistent with the theory that the collagen fiber network is responsible for limiting distension of the lung. This report considers saline-filled volume-pressure curves studied in excised hamster lungs after incubation with endotracheally instilled pancreatic elastase or clostridial collagenase solutions. Fluid retained in the lungs after the first infusion-withdrawal cycle was significantly greater in lungs treated with elastase than in lungs treated with collagenase or in control lungs. Total fluid volume at full inflation was similar in the 3 groups. Chord compliance of lungs treated with collagenase was greater at high volume range than that in lungs treated with elastase or control lungs; chord compliance of elastase-treated lungs was higher at mid-volume range than that of collagenase-treated or control lungs. The results of these in vitro studies are consistent with the theory of independently functioning elastic and collagen fiber networks, with the latter limiting lung distensibility at high volumes, and the former providing great extensibility at low volumes. Events that are part of the repair process after elastase injury may result in a change in the orientation of collagen in alveolar tissue and appear to account for the differing effects of in vivo and in vitro elastase treatment on the static mechanical properties of the lungs.

Animals↗