Search PubMed⌕ Search

Biomedical subjects

A Rojas

Publications and source records attributed to A Rojas.

At least 181 records · Page 10Linked to original sources
PubMed1975

Dermal exudate macrophages. Induction in dermal chambers and response to lymphokines.

Chambers were implanted in the dorsum of guinea-pigs at the dermal-subcutaneous junction. Exudates were induced and harvested. Macrophages obtained were able to migrate in vitro. If procured from sensitized donors, macrophage migration was inhibited by the corresponding antigen. Dermal exudate macrophages are therefore subject to the effect of lymphokines. The chamber model may be useful for in vivo studies of cell to cell and cell-parasite interactions.

Animals↗
PubMedDate not supplied

Experimental radiotherapy with WR-2721 and misonidazole.

The data from a large series of experiments on mouse skin and tumors are summarized. Radioprotection with WR-2721 has been observed in both tumors and normal tissues. The protection factors are generally, but not always, higher for skin than for tumors. The protection observed in skin is greater for mice irradiated breathing air than for those irradiated in oxygen. It is postulated that the different protection factors observed in different normal tissues and tumors may reflect differences in tissue oxygenation levels. The combination of misonidazole and WR-2721 has been studied in terms of the modification of radiosensitivity and also as the modification of lethal toxicity. An interaction has been observed in all aspects. The toxicity of WR-2721 increases in the presence of misonidazole. The WR-2721 radioprotection of both skin and tumors decreases if the sensitizer is added. Likewise the radiosensitization with misonidazole is diminished when WR-2721 is present. These results indicate an interaction at the site of radiation injury and they also demonstrate that WR-2721 can adequately penetrate into hypoxic tumor cells.

Amifostine↗
PubMedDate not supplied

Radioprotection of mouse skin by WR-2721: the critical influence of oxygen tension.

The epidermal clone assay has been used to study the radioprotective effect of WR-2721 on mouse skin under different conditions of oxygenation and under anoxia. The skin has shown a progressive decrease in sensitivity as the inspired gas was changed from 100% oxygen towards 0% oxygen. Compared with mice breathing 100% oxygen, those breathing air are partially protected. The inspired oxygen concentration to given half the full oxygen effect is 10--12%. The radioprotection observed with 400 mg/kg WR-2721 is markedly dependent on the ambient oxygen concentration. The protection factor is 1.1 or less in mice breathing 5%, 1% of 0% oxygen. Protection is maximal (1.95) in air and in 50% oxygen and diminishes to 1.6 at higher oxygen tensions.

Amifostine↗
PubMedDate not supplied

Molecular analysis of SRY gene in patients with mixed gonadal dysgenesis.

Mixed gonadal dysgenesis (MGD) includes a group of heterogeneous conditions consisting of a dysgenetic testis with a streak gonad. MGD is probably due to a disturbance in testicular determination/differentiation. The objective of this study is to analyze the SRY gene in MGD patients. A molecular investigation was undertaken in sixteen patients with this disorder in an attempt to determine mutations in SRY through polymerase chain reaction, single strand conformational polymorphism and direct sequencing. Eleven patients showed 45,X/46,XY and five 46,XY karyotype. Mutations in SRY gene were shown to be absent in these patients. This study confirms the findings of other studies. The etiology of MGD is heterogeneous, and cytogenetics mosaicism typically seen in these patients may be a cause of this condition, although, the presence of mutations in testicular organizing genes downstream of SRY is still to rule out.

Alleles↗
PubMedDate not supplied

Heparin and low molecular weight heparin decrease nitric oxide production by human polymorphonuclear cells.

BACKGROUND: Heparin and heparin derivatives with low anticoagulant activity exhibit a wide spectrum of biological functions affecting adhesion, activation and trafficking of leukocytes. METHODS: We investigated the in vitro effect of heparin and a low molecular weight heparin derivative (LMWH) on nitric oxide (NO) production by human polymorphonuclear leukocytes (PMN). RESULTS: N-formyl-methionyl-leucyl-phenylalanine (fMLP)-stimulated NO production was significantly decreased by heparin at doses of 0.5 and 5 micrograms/mL, while LMWH was only effective at doses of 50 and 200 micrograms/mL by means of a mechanism not related to NO synthase (NOS) activity. CONCLUSIONS: These results support the hypothesis that heparin and LMWH derivatives may offer therapeutic benefit for inflammatory diseases where NO plays a protagonic role.

Heparin↗