RESUMO
The nonelastolytic proteases trypsin and chymotrypsin were administered to hamsters 24 hours after intratracheal injection of elastase. Severity of the disease, extent of degradation and resynthesis, new cross-link formation, and the levels of the enzyme lysyl oxidase, which mediates the cross-link formation, were compared with the same parameters measured in hamsters with experimental emphysema induced by elastase alone. Increases in mean linear intercept indicated that a more severe form of the disease was produced. Although elastin degradation after 1 week was similar in both groups, resynthesis of the elastin destroyed by the elastolytic insult was significantly impaired in the animals injected sequentially with elastase and trypsin or chymotrypsin. Formation of new elastin as monitored by 14C-lysine incorporation into the elastin specific cross-links desmosine and isodesmosine was reduced approximately 40%, although there was no significant difference in the levels of lysyl oxidase activity. It is suggested that the most likely mechanism compatible with the recorded observations involves destruction of the microfibrillar component of the elastic fiber by trypsin or chymotrypsin, resulting in the absence of the requisite template for resynthesis of the pulmonary elastin.
Assuntos
Elastina/biossíntese , Pulmão/metabolismo , Elastase Pancreática/farmacologia , Enfisema Pulmonar/metabolismo , Tripsina/farmacologia , Animais , Quimotripsina/farmacologia , Cricetinae , Desmosina/biossíntese , Modelos Animais de Doenças , Feminino , Isodesmosina/biossíntese , Pulmão/patologia , Lisina/metabolismo , Mesocricetus , Proteína-Lisina 6-Oxidase/metabolismo , Enfisema Pulmonar/induzido quimicamente , Enfisema Pulmonar/patologiaRESUMO
Mature, crosslinked elastin has been isolated from 4 human and 12 monkey uterine cervices. A modification of previous methods for determination of elastin content was devised to quantitate the low amounts of elastin in the crude connective tissue of uterine cervices. The percentage of elastin was found to range between 0.9 and 2.4% and did not appear to change at various stages of gestation.
Assuntos
Colo do Útero/análise , Elastina/isolamento & purificação , Aminoácidos/análise , Animais , Fenômenos Químicos , Química , Cromatografia em Papel , Tecido Conjuntivo/análise , Tecido Conjuntivo/ultraestrutura , Feminino , Humanos , Macaca mulatta , Macaca nemestrina , GravidezRESUMO
A new method of preparation of lung parenchyma free from small and medium sized airways and blood vessels is described. The lung is frozen in the inflated state and cut into thin slices to facilitate visualization and separation of large blood vessels and airways. With the aid of a special steel brush mounted on a kitchen blender most of the smaller as well as medium sized blood vessels and airways are easily shaved off and subsequently separated from the parenchyma by sieving through a 20-mesh sieve. The fall-through portion consists almost entirely of alveoli. Amino acid analysis of elastin separated from the sieved fragments is similar to lung parenchymal elastin isolated and dissected from fresh lung tissue.