BACKGROUND: The versatility of HSV-1 vectors includes large transgene capacity, selective replication of mutants in dividing cells, and availability of recombinant virus (RV) and plasmid-derived (amplicon) vectors, which can be propagated in a co-dependent, 'piggyback', manner. METHODS: A replication-defective piggyback vector system was generated in which the amplicon carries either of two genes essential for virus replication, IE2 (ICP27) or IE3 (ICP4), as well as lacZ; the RV is deleted in both these genes, and vector stocks are propagated in cells transfected with one of the complementary genes. In the replication-competent system, the amplicon carries the IE2 and lacZ; the RV had a large deletion in the IE2; and stocks are propagated in untransfected cells. Titers over successive passages, recombination between amplicon and RV, and the structural integrity of vector genomes were evaluated. The replication-competent system was tested for therapeutic efficacy in subcutaneous 9L gliosarcoma tumors in nude mice with activation of ganciclovir via the viral HSV-thymidine kinase gene. RESULTS: Both systems generated high titer amplicon vectors (about 10(7) tu/ml) and amplicon:RV ratios (0.6-3.0). No replication-competent RV was generated in either system. The replication-defective system showed low toxicity and increased packaging efficiency of amplicon vectors, as compared to single mutant RV helper virus. The replication-competent system allowed co-propagation of amplicon and RV; injection into tumors followed by ganciclovir treatment inhibited tumor growth without systemic toxicity. CONCLUSION: New replication-defective and replication-competent piggyback HSV, vector systems allow gene delivery via amplicon vectors with reduced toxicity and co-propagation of both RV and amplicon vectors in target cells, with effective tumor therapy via focal virus replication and pro-drug activation.

Animals↗

PubMedDate not supplied

An intracellular transit iron pool.

It seems likely that iron which has crossed the cell membrane and has been released from transferrin enters a labile intermediate pool from which it is available for haem synthesis, for the activation of iron-dependent enzymes, for incorporation into ferritin or for a return to extracellular transferrin. Enlargement of this pool stimulates ferritin synthesis. Iron probably enters the transit pool not only from transferrin but also as a result of endogenous haem breakdown and the mobilization of ferritin iron. Evidence for the occurrence of the transit pool has been obtained for reticuloendothelial cells, red cells precursors, cultured Chang cells and liver. It is suggested that the transit pool consists of a low molecular weight complex and that this is a major source of the iron chelated by agents such as desferrioxamine. No more precise characterization has been possible up to the present time.

Animals↗

PubMedDate not supplied

Source and function of keto elaidic acids from lungs of cotton workers.

A series of cytotoxic oxygenated derivatives of oleic acid, 8-oxo-9, 9-oxo-10, 10-oxo-8-, and 11-oxo-9 trans octadecenoic acid, uniquely found at post-mortem in airway cells of cotton workers, were synthesized and shown to be cytotoxic, i.e., inhibitory of growth for several cell lines, including HL-60 and U-937 promyelocytes and Eagle's KB carcinoma cells. At microM concentrations, the 8- and 11- keto acids: are chemokinetic for human neutrophils; activate production of O2-. and H2O2; stimulate promyelocytes in culture to differentiate into neutrophils; and increase diglyceride metabolism in inflammatory cells. These results indicate that these four monooxygenated fatty acids, which are found in airways of cotton workers and initiate both inflammation and differentiation in vitro, may be etiologic in the abnormal differentiation and inflammation seen in small airways of cotton workers. This abnormal differentiation in bronchi may result from altered diglyceride metabolism with resultant activation of phosphoprotein kinase C initiated by the keto fatty acids.

Cells, Cultured↗

PubMedDate not supplied