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118 records · Page 7Linked to original sources
PubMed1984

[Incorporation of L-azetidine-2-carboxylic acid into collagen of the skin. Structural changes].

As previously shown by two dimensional thin-layer chromatography L-azetidine-2-carboxylic-acid (L-Az) is incorporated into type I skin collagen instead of proline when 3 week old mice are fed with a 0,1% solution of L-Az orally. Ultrastructural investigations did not reveal significant changes in collagen periodicity and on fibril diameter. The collagen fibrils of the upper papillary dermis seemed to be packed more densely, sometimes only one electron dense lamina was seen instead of basal lamina and plasma membrane. The glycosaminoglycane-induced fibrillogenesis was not changed in contrary to the collagen-heat-gelation fibrillogenesis at 37 degrees C, where no gel aggregation could be seen. The reconstruction of native fibres from collagen solutions was disturbed too, several finer precipitated fibrils being detectable. On infrared spectroscopy significant differences in absorption spectra were detected. Correlating with previous results of reduced tensile strength and normal melting point of L-Az collagen we can conclude that L-Az might cause rather intermolecular than intramolecular disturbances of crosslinking.

Animals↗
PubMed1983

Synthesis and biological activity of some new benzimidazolyl-azetidin-2-ones and -thiazolidin-4-ones.

Arylidene-2-aminobenzimidazoles (1) were prepared by condensation of 2-aminobenzimidazole with aromatic aldehydes. Cyclocondensation of mercaptoacetic acid, chloracetylchloride and phthaloyl glycyl chloride on 1 giving the corresponding 4-thiazolidinones (2) and azetidinones (3 and 4) respectively, in good yields. The biological activities of the prepared compounds were screened against several strains of bacteria.

Anti-Bacterial Agents↗
PubMed1983

[Incorporation of L-acetidine-2-carboxylic acid in type I skin collagen. Biochemical and mechanoelastic properties].

In order to elucidate the role of L-acetidine-2-carboxylic acid (L-ac) incorporated into collagen type I of the skin instead of proline, we looked for the mechanoelastic properties of skin. Mice were orally fed with 0, 1% solution of L-ac for 5 weeks, then sacrificed, and type I collagen was extracted. Incorporation of the proline analogue (L-ac) could be shown by two dimensional thinlayer chromatography. The melting point (Tm) of type I collagen was determined by circular dichroism: 36, 5 +/- 1 degrees C for normal collagen, 37 +/- 1 degrees C for L-ac-collagen. This insignificant difference indicates that there was no alteration of the thermal stability of the collagen helix after incorporation of L-ac. Tensile strength was examined on whole strips of skin and worked out at means = 1,00 N/mm, s = 0,20 N/mm, sigma = 0,04 N/mm for normal individuals and means = 0,62 N/mm, s = 0,24 N/mm, sigma = 0,05 N/mm for L-ac-fed animals. The considerable difference could be estimated by the Wilcoxon test (p less than 0,005). As the stability of the collagen helix (shown through melting point determination) has not decreased, the reduced mechanoelastic property of tensile strength seems to be due to intermolecular rather than to intramolecular disturbances of the cross connection of the triple helix.

Animals↗
PubMed1982

Aortic endothelial cell migration. I. Matrix requirements and composition.

Endothelial cell migration was studied following a mechanical injury produced in cultured confluent monolayers of calf aortic endothelium with the use of a quantitative migration assay. In this method the cells were grown on glass coverslips coated with scarlet red-containing Formvar. At confluency, the cultures were cut in half with a blade; one half was removed with the pigmented Formvar, and the other was returned to culture. Migration was linear for a least 96 hours, and was due to cell motility, not proliferation. Since it was blocked in the presence of L-azetidine carboxylic acid or cis-hydroxyproline, inhibitors of collagen secretion, endothelial cell migration appeared to be dependent on the continual secretion of collagen. Furthermore, the types, apparent relative amounts, and localizations of the collagens as well as laminin changed during the migratory process. These studies support the notion that the aortic endothelial cell migratory response to injury is a dynamic one requiring the continual secretion and modulation of matrix molecules.

Animals↗
PubMed1975

[The effect of an L-proline analogue, L-azetidine-2-carboxylic acid, on the phenotypic differentiation of the somite mesenchyme of chick embryos].

L-azetidine has been utilized in vivo and in vitro. In vivo, the substance is injected into the yolk sac of young embryos. It inhibits the secretion of the periaxial extracellular material resulting in a lack of several vertebrae. In young vertebral primordia, cultured on L-azetidine, the myotome cells differentiate into myoblasts whereas the sclerotome cells remain undifferentiated. In older primordia, the sclerotome cells give rise to abnormal cartilage but the myotome cells seldom differentiate.

Age Factors↗
PubMed1996

[Studies of in vitro and in vivo derived 1,2-diazetine and nitronylnitroxide as donors and acceptors of nitric oxide].

The series of nitronylnitroxyl radicals (NNR) were studied as paramagnetic scavengers of nitric oxide. These radicals react with NO with rate constants of (0.6-1.1).10(4) M-1.sec-1 forming stable iminonitroxyl radicals. They can be used to assay nitric oxide in solutions by EPR spectroscopy; the sensitivity of the method is 1 microM for the detection of NO concentration and 0.3 nM/sec for the measurements of the rates of NO generation for 1 h in 0.2 ml sample. To overcome fast reduction of the radicals in biological samples, charged NNR was incorporated into the inner volume of large unilamellar phosphatidylcholine liposomes thus decreasing the rates of NNR reduction about 1000-fold. The method was used for the NO synthase activity assay in rat cerebellum cytosol. NNR was used to study the kinetics of the decomposition of 3,4-dihydro-1,2-diazete 1,2-dioxides (DD). Several DD derivatives at 5-80 microM concentrations are very effective vasodilators in perfused rat tail artery. Intraperitoneal injection of several DD (40-200 micrograms/kg weight). in hereditary hypertensive rats (ISIAH-strain) significantly (by 30%) decreased systolic arterial blood pressure whereas similar effect of trinitroglycerin was detected at significantly higher dose (900 micrograms/kg weight).

Animals↗