RESUMO
The results of 3 sets of experiments on the effects of 22 microT sinusoidal 50 Hz magnetic fields (MF), applied for 1 h on 5 successive days (1 h/5 days), on the level of host defense and on spleen colony formation are reported. The first set of experiments shows the effects on the number of colony-forming units (CFUs) on the spleen and on the cellularity of the thymus in mice. The MF exposures resulted in an increase in CFUs which was statistically significant with respect to the controls, but not with respect to the shams. Statistically significant changes in the thymic weight and thymic index with respect to both the controls and the shams were measured 1 h after the last MF exposure. In the second set of experiments, the mice were given a sublethal dose of X-rays (6 Gy), which was followed by exposure 2 h later to the MF. The MF exposure was repeated at the same time of day for 5 days. The number of colonies per spleen showed a consistent, statistically significant increase with MF exposure and the number of CFUs per femur was decreased. In the third set of experiments, bone marrow was taken from mice which had been exposed to 22 microT fields and injected into mice which had been exposed to a lethal dose of X-rays (9 Gy). The number of CFUs per femur in the recipient mice was shown to be reduced by a statistically significant amount at 1 and 4 days after injection.
Assuntos
Células-Tronco Hematopoéticas/citologia , Imunidade Celular/imunologia , Magnetismo , Baço/citologia , Análise de Variância , Animais , Células da Medula Óssea/citologia , Células da Medula Óssea/efeitos da radiação , Transplante de Medula Óssea , Fêmur/citologia , Fêmur/efeitos da radiação , Células-Tronco Hematopoéticas/efeitos da radiação , Imunidade Celular/efeitos da radiação , Indicadores e Reagentes , Masculino , Camundongos , Camundongos Endogâmicos CBA , Nitroazul de Tetrazólio , Tamanho do Órgão , Fagocitose , Doses de Radiação , Baço/efeitos da radiação , Staphylococcus aureus/imunologia , Timo/citologia , Timo/efeitos da radiação , Raios XRESUMO
Porcine leukocytes contained three homologous peptides, PG-1, 2 and 3, that manifested potent microbicidal activity against Escherichia coli, Listeria monocytogenes and Candida albicans in vitro. The peptides ('protegrins') were composed of 16 (PG-2) or 18 amino acid residues, and, like tachyplesins (broad-spectrum antibiotic peptides of horseshoe crab hemocytes), they contained two intramolecular cystine disulfide bonds. Considerably smaller than defensins, protegrins nevertheless showed substantial homology to them, especially to the 'corticostatic' rabbit defensin, NP-3a. The relatively simple structure of protegrins should provide useful prototypes for constructing congeners with selectively enhanced host defense activities.