PubMed Health⌕ Search

Biomedical subjects

L Diaz de Leon

Publications and source records attributed to L Diaz de Leon.

7 recordsLinked to original sources
PubMed1998

Inhibitory effect of propranolol on lipid synthesis in gonadectomized male hamster flank organs.

BACKGROUND: This paper describes the inhibitory effect produced by propranolol pre-treatment on lipid synthesis in flank organs from intact, gonadectomized, and isoproterenol-treated male hamsters. Furthermore, the effect induced by the same treatments on gland sebum composition is reported. METHODS: Different groups of male hamsters were injected daily with propranolol, isoproterenol or propranolol plus isoproterenol. Treatment-effect was evaluated determining the in vitro incorporation of radioactive acetate into lipids in hamster flank organs from intact and castrated animals. Additionally, radiolabeled lipids were isolated and identified using TLC and autoradiography as methods. RESULTS: Results demonstrate that castration significantly decreases lipid synthesis in male hamster flank organs. In addition, propranolol treatment inhibits such synthesis in glands from intact, gonadectomized, and isoproterenol-treated animals. However, isoproterenol treatment was ineffective when compared to intact or gonadectomized control vehicle-treated animals. Lipid classes isolated and identified lipids either in castrated or in drug-treated animals were phospholipids, cholesterol, monoglycerides, fatty acids, waxes and cholesterol esters. CONCLUSIONS: Results indicate an inhibitory effect induced on lipid synthesis by beta-adrenergic receptor antagonists; however, beta-adrenergic agonists drugs do not stimulate it. Data suggest a permissive role of adrenergic hormones on lipid synthesis in intact and in gonadectomized animals. Furthermore, castration decreased the synthesis, suggesting that a tight coupling between beta-adrenergic receptors and androgen receptors may be a prerequisite for lipogenesis in this tissue. Pre-treatment does not modify sebum composition in gonadectomized animal glands. These data support the evidence that activation of beta-adrenergic receptors could be an independent factor in the lipid composition regulation process.

Animals↗
PubMed1988

Mononuclear cell-fibroblast interactions in scleroderma.

We studied cell proliferation and collagen biosynthesis in cocultures of dermal fibroblasts with peripheral blood mononuclear cells (MNC) from scleroderma patients and from age-matched normal controls. Autologous one-way mixed MNC-fibroblast cultures revealed that fibroblasts do not stimulate MNC proliferation. Conversely, MNC stimulate autologous fibroblasts from scleroderma patients as well as from normal controls. This effect is increased in cells from scleroderma patients in which it seems to be mediated both by cell-to-cell interaction and through the production of soluble factors by MNC. In normal control cell systems we found no proliferative effect of supernatants of unstimulated cells or from those stimulated in autologous mixed-lymphocyte reactions. Coculture of fibroblasts with autologous MNC resulted in increased [14C]proline incorporation into both collagenic and noncollagenic proteins. This effect was mediated mostly by soluble factors that are released into the culture medium. Protein synthesis by MNC-fibroblast cocultures from scleroderma patients was significantly greater than protein synthesis by those from normal controls. Culture supernatants from unstimulated MNC or from autologous mixed-lymphocyte cultures caused a slight decrease in collagenic protein synthesis by cultured fibroblasts from scleroderma patients but not by those from normal controls. This effect of culture supernatants could be reproduced, and magnified, with purified IL-1 on cells from either patients or controls. Our findings indicate abnormal MNC-fibroblast interactions in scleroderma that could play an important role in the pathogenesis of fibrosis, the hallmark of this condition.

Adult↗
PubMed1983

Histological and biochemical characterization of murine sarcomas.

A mouse fibrosarcoma and rat osteosarcoma were examined histologically and biochemically with regard to collagen content. The fibrosarcoma was composed of undifferentiated mesenchymal cells without distinct fibroblastic characteristics. Collagen production and deposition were consistent with those observed in cultured fibroblasts. Type I and type III collagens were evident as determined by immunofluorescence staining and biochemical analysis. The osteosarcoma appeared similar to bone with regard to a high content of type I collagen, limited calcification and poor vascularization. While these sarcomas do not histologically resemble their non-transformed counterparts, analysis of their macromolecular composition confirmed the identity of their presumed cell of origin. Similar methodology could be readily applied for identification and classification of human malignant sarcomas.

Amino Acid Sequence↗
PubMed1980

Partial characterization of procollagen messenger ribonucleic acid in a murine chondrosarcoma.

Cells from a rat chondrosarcoma in primary suspension culture were used for labeling studies and isolation of RNA. With extended labeling, a distinct fraction of poly(A+)RNA sedimented in the region of 26S on denaturing sucrose gradients. Similar profiles were obtained with labeled poly(A+)RNA isolated from normal cartilage tissues, as well as from chondrocytes in culture. This mRNA coded for collagenous protein when translated in a cell-free system derived from wheat germ. Among the polypeptides synthesized in vitro, one distinctive component of approximately 150,000 daltons was detected by gel electrophoresis. Polypeptides of identical size, sensitive to bacterial collagenase, were also synthesized in vitro by polysomes isolated from the chondrosarcoma.

Animals↗
PubMed1978

The synthesis of presumptive procollagen messenger ribonucleic acid in the calvaria of the developing chick embryo.

The presumptive messenger RNAs for type I procollagen were isolated from chick embryo calvaria at various stages of development. Poly(A)-containing RNA fractions from denaturing sucrose gradients directed protein synthesis in a cell-free system derived from wheat germ. Procollagen mRNA activity was detected in a region of about 26 S. Approx. 80% of the labeled proline incorporated into cell-free product was susceptible to digestion by purified bacterial collagenase. The synthesis of procollagen mRNAs was followed during development. Comparison of the in vitro labeled mRNAs from calvaria of day 12--16 embryos indicated that the 26 S component was most pronounced at day 13 and decreased progressively towards day 16. In addition, incubation of calvaria with tritiated nucleosides for 1.5--25 h revealed that 26 S mRNA was significantly labeled only after prolonged periods. The results suggest that procollagen mRNA is a relatively stable species with a prolonged half-life compared to the majority of mRNAs in this tissue.

Animals↗