Phototoxic liposomes coupled to an antibody that alone cannot modulate its cell-surface antigen kill selected target cells

Summary Molecules such as antibodies that bind to cell surfaces can be used to deliver cytotoxic drugs to selected cells. To be effective the drug must usually be taken into the cells by endocytosis. In this study a T-cell line (CCRFCEM) was effectively killed by liposomes carrying a photosensitizer and bearing the antibody OKT4 (anti-CD4). The unconjugated antibody does not induce antigenic modulation in the target cells, an indication of the absence of endocytosis, and would therefore not normally have been selected as an agent for drug delivery. It cannot, however, be concluded with certainty that the conjugates act at the cell surface and several alternative explanations of their efficacy are offered.     

Hippocampal electrical activity and gamma-aminobutyrate metabolism in brain tissue following administration of homocysteine

Abstract: The concentration of γ-aminobutyrate (GABA) and the activity of glutamate decarboxylase and GABA-transaminase were measured in extracts of mouse brain before the onset and during the course of generalized seizures induced by systemic administration of homocysteine thiolactone. The results indicate that whole brain GABA metabolism is unaffected by subconvulsive and convulsive doses of homocysteine at all stages of the generalized seizure. Electroencephalographic monitoring of rat brain electrical activity via hippocampal electrode implantation allowed the course of homocysteine-induced seizures to be followed and afforded a means of quantifying such seizures.     

N-cyanoimidazole and diimidazole imine: water-soluble condensing agents for the formation of the phosphodiester bond

The reaction of BrCN with imidazole results in the formation of N-cyanoimidazole and diimidazole imine. These compounds were shown to be useful condensing agents for the formation of the phosphodiester bound in aqueous solution.     

Lethality of palindromic DNA and its use in selection of recombinant plasmids

A plasmid derived from ColE1 is constructed so that the removal of one restriction endonuclease HindIII fragment allows the ends of the remaining single fragment (the replicator) to be joined, generating a palindromic sequence 2394 bp in length. The circular species thus produced gives rise to transformants of E. coli at very low frequency. Since the palindromic sequence is effectively lethal to a plasmid containing it, the replicator will give rise to more transformants when the restriction fragment originally removed from it is replaced by another. This principle can be exploited to allow the efficient molecular cloning of unselected restriction fragments.     

Immunity in human schistosomiasis

Field studies on immunity in human schistosomiasis are expensive, labour-intensive and extremely time-consuming, requiring many years to yield even provisional results. In this review, Anthony Butterworth and Paul Hagan summarize the need for such studies, the evidence for immunity in man, the immunological factors that may govern the expression of immunity, and the implications of such work for the development of new methods of control through vaccination.