Resistance to hygromycin B : A new marker for plant transformation studies.

A bacterial gene encoding hygromycin phosphotransferase has been modified for expression in tobacco cells. The aphIV gene from Escherichia coli was inserted between the 5' sequence of an octopine synthase gene and the 3' sequence from a nopaline synthase gene. The new gene was incorporated between T-DNA border fragments in the broad-host-range vector pKT210 to form a micro-Ti plasmid. Agrobacterium tumefaciens containing this plasmid and a Ti plasmid as helper was used to incite crown gall tumors on aseptic tobacco plants. Samples of these galls could grow in the presence of hygromycin B, provided that the aph gene had been fused with the ocs gene to maintain the sense of the coding sequences. When the genes had been fused in the reverse 'antisense' orientation none of the gall samples could grow on hygromycin. Unlike wild-type galls the hygromycin-resistant tissue contained DNA sequences homologous to the aphIV gene. Thus the modified gene can be introduced into tobacco cells and confer on them the ability to grow in the presence of hygromycin B.

Pupillary and iridovitreal block in pseudophakic eyes.

Twenty-six cases of pupillary and iridovitreal block in pseudophakic eyes are reported. Although ten patients presented with acute angle closure glaucoma, the majority were asymptomatic and had normal intraocular pressures. While cure was finally achieved in all cases, recurrence of block occurred in six eyes as late as two months after initial successful treatment. A variety of therapeutic modalities including argon laser iridectomy, argon laser gonioplasty (iridoplasty), surgical iridectomy, surgical vitrectomy, Q-switched Nd:YAG laser iridectomy and Nd:YAG laser photodisruption of the anterior vitreous face were needed. Despite successful relief of pupillary and iridovitreal block in these eyes with no evidence of glaucoma prior to cataract and lens implant surgery, four eyes developed eight or more clock hours of peripheral anterior synechiae, and nine eyes continue to require chronic medical therapy for glaucoma.

Interferon induction and macrophage activation by a mycovirus double-stranded RNA/tobramycin complex following treatment with human serum.

Double-stranded RNA (dsRNA) molecules, generally effective inducers of interferon (IFN), have a weak potency in man apparently because of the presence of a serum RNAase which quickly inactivates extracellular dsRNA. We have discovered that tobramycin, an aminoglycoside, protects Penicillium chrysogenum mycovirus dsRNA (PCMdsRNA) from the degradative action of the nuclease. Exposure of the dsRNA/tobramycin complex to human serum results in some degradation, but still permits the production of significantly high titers of IFN upon injection into mice. Intraperitoneal (i.p.) treatment of CFI mice with both dsRNA and dsRNA/tobramycin complex activated macrophages to inhibit the growth of P815 mastocytoma target cells. Following in vitro treatment with human serum, free dsRNA failed to activate peritoneal macrophages in vivo under conditions where this activity of dsRNA/tobramycin complex was retained. By varying the ratio of moles of tobramycin (as free base) to the moles of RNA phosphorous, toxicity can be minimized, while retaining the biologic activities of dsRNA.

Lack of effect on cyclic GMP content of cells treated with mycophenolic acid.

Mycophenolic acid, an oncolytic agent and a known inhibitor of guanine ribonucleotide synthesis, has proven to be an effective drug against psoriasis. With reports of greater guantities of c-GMP in psoriatic tissues than in normal tissue, and with the correlation of c-GMP content of cells to proliferation, the effect of mycophenolic acid on cellular c-GMP was investigated. When HeLa, green monkey BSC-1, and mouse L-cells were treated with inhibitory concentrations of mycophenolic acid, no decrease in c-GMP was observed from that of untreated cells. Though mycophenolic acid inhibits guanine ribonucleotide synthesis, this inhibition does not extend to c-GMP synthesis. The inhibition of proliferation of cells by mycophenolic acid then does not include the inhibition of synthesis of c-GMP, but apparently resides solely in limiting the guanylate necessary for nucleic acid synthesis.