The effect of cysteine on the immunosuppressive activity of busulphan, cyclophosphamide and nitrogen mustard

Gamma-irradiation depletes endogenous germ cells and increases donor cell distribution in chimeric chickens

The production of chimeric birds is an important tool for the investigation of vertebrate development, the conservation of endangered birds, and the development of various biotechnological applications. This study examined whether gamma (γ)-irradiation depletes endogenous primordial germ cells and enhances the efficiency of somatic chimerism in chickens. An optimal irradiation protocol for stage X embryos was determined after irradiation at various doses (0, 100, 300, 500, 600, 700, and 2,000 rad). Exposure to 500 rad of γ-irradiation for 73 s significantly decreased the number of primordial germ cells (P < 0.0001). Somatic chimera hatchlings were then produced by transferring blastodermal cells from a Korean Oge into either an irradiated (at 500 rad) or intact stage X White Leghorn embryo. An analysis of feather color pattern and polymerase chain reaction-based species-specific amplification of various tissues of the hatchlings confirmed chimerism in most organs of the chick produced from the irradiated recipient; a lesser degree of chimerism was observed in the non-irradiated control recipient. In conclusion, the exposure of chick embryos to an optimized dose of γ-irradiation effectively depleted germ cells and yielded greater somatic chimerism than non-irradiated control embryos. This technique can be applied to interspecies reproduction or the production of transgenic birds.

Production of germline chimeric chickens following the administration of a busulfan emulsion

Busulfan (1,4-butanediol dimethanesulfonate) was used to deplete endogenous germ cells for the enhanced production of chicken germline chimeras. Utilizing immunohistochemical identification of primordial gem cells (PGCs) in Stage 27 chicken embryos, two delivery formulations were compared relative to the degree of endogenous PGC depletion, a busulfan suspension (BS) and a solublized busulfan emulsion (SBE). Both busulfan treatments resulted in a significant reduction in PGCs when compared to controls. However, the SBE resulted in a more consistent and extensive depletion of PGCs than that observed with the BS treatment. Repopulation of SBE-treated embryos with exogenous PGCs resulted in a threefold increase of PGCs in Stage 27 embryos. Subsequently, germline chimeras were produced by the transfer of male gonadal PGCs from Barred Plymouth Rock embryos into untreated and SBE-treated White Leghorn embryos. Progeny testing of the presumptive chimeras with adult Barred Plymouth Rock chickens was performed to evaluate the efficiency of germline chimera production. The frequency of germline chimerism in SBE-treated recipients increased fivefold when compared to untreated recipients. The number of donor-derived offspring from the germline chimeras also increased eightfold following SBE-treatment of the recipient embryos. These results demonstrated that the administration of a busulfan emulsion into the egg yolk of unincubated eggs improved the depletion of endogenous PGCs in the embryo and enhanced the efficiency of germline chimera production.

Toxicological review of busulfan (Myleran)

Busulfan is a bifunctional alkylating agent that appears to be cytotoxic to slowly proliferating or non-proliferating stem cell compartments, although its specific molecular and cellular mechanisms are unknown. It is the drug of preference in treatment of chronic myelogenous or granulocytic leukemia because its cytotoxic activity results in primary damage or destruction of hematopoietic cells. Additional effects resulting from the cytotoxicity of busulfan in hematological and other tissues, as documented by both human and animal model studies, include lethality, sterility, teratogenicity, and alteration of immune function. Busulfan has been shown to be mutagenic to microorganisms, mammalian cells in culture, Drosophila, and rodents. This agent is also considered potentially carcinogenic to humans. Various tissue hyperplasia and preneoplastic cells have been observed in animal model studies with busulfan, and case reports on human patients implicate busulfan as the causative agent in induction of secondary malignancies. Reports from human and animal studies of busulfan's cytotoxicity, teratogenicity, carcinogenicity, and mutagenicity have been reviewed. This information may be useful in a quantitative assessment of the effects of this agent and the identification of significant deficiencies in the data base. Demonstration that busulfan induces mutations in both somatic and germ cells suggests the need to assess its risk to humans.

Busulfan-induced hemorrhagic cystitis

A case of a busulfan-induced hemorrhage cystitis is reported. Spontaneous resolution occurred following cessation of the drug. The similarity between the histologic appearances of busulfan cystitis and both radiation and cyclophosphamide-induced cystitis is discussed and the world literature reviewed. In view of the known tendency of busulfan to induce cellular atypia and carcinoma in other sites, periodic urinary cytology is suggested in patients on long-term therapy.