The identification and testing of interaction patterns

This paper presents a method for identifying and assessing the significance of interaction patterns among various chemicals and chemical classes of importance to regulatory toxicologists. To this end, efforts were made to assemble and evaluate experimental data on toxicologically significant interactions, to use this information to characterize the consistency of toxicological interactions, and to define classes of compounds that display similar toxicological interactions. The motivation for this effort is to be able to propose hypotheses, which can be validated by experimentation, on how 2 or more chemicals will interact.

Kinetic characterization of the interaction of biotinylated human interleukin 5 with an Fc chimera of its receptor alpha subunit and development of an ELISA screening assay using real-time interaction biosensor analysis

The interaction of biotinylated human interleukin 5 ([BT]hIL5) with immobilized receptor was measured with a real-time biosensor, and these results were used as a basis for configuring an ELISA for screening antagonists of hIL5-receptor binding. The recombinant proteins used, hIL5 and shIL5R alpha-Fc (chimeric fusion receptor constructed by linking the soluble component of the hIL5 receptor alpha subunit to the constant domain (Fc) of immunoglobulin G), were produced by the expression of cloned vectors in Drosophila schneider (S2) cells. Initial attempts to develop a screening assay by direct immobilization of soluble IL5 receptor to microtiter plates proved unsatisfactory and led to use of the Fc chimera attached by oriented immobilization via protein A. Hence, shIL5R alpha-Fc was bound to protein A covalently immobilized on a carboxymethyl dextran (CM-5) biosensor chip. Specific binding was demonstrated of [BT]hIL5 to protein A/shIL5R alpha-Fc receptor complex. The binding was high affinity (Kdapp = 6 nM), reversible and saturable. The affinity of [BT]hIL5 was similar to that determined with the biosensor assay for unmodified hIL5. The observed kinetics of the interactions of Fc chimera with protein A (slow dissociation) and of [BT]hIL5 with immobilized Fc chimera (faster dissociation) were favorable for subsequently establishing a microtiter plate based ELISA assay. In the latter, Fc chimera was immobilized to the plate via protein A as in the biosensor experiment. Binding of [BT]hIL5 to immobilized Fc chimera in the ELISA was concentration dependent and was competed by both hIL5 and shIL5R alpha.(ABSTRACT TRUNCATED AT 250 WORDS)

The diffusion of ophthalmic laser in Australia

This paper demonstrates the diffusion of ophthalmic laser into the Australian health care system. Australian ophthalmologists were quick to adopt the use of laser. Argon laser was introduced three years after its first use in the USA; YAG laser the same year as its use in the USA and Dye laser two years after its introduction in the USA. In the years 1975-84 there had been a gradual introduction of laser into ophthalmic practice growing from three to 39 in that period. From the end of 1984 to June 1986 the number increased by 68, an increase so sharp as almost to defy the classical S curve. The rapid rise can be attributed to its increased use in diabetic retinopathy, retinal vascular disease, senile macular degeneration, glaucoma and to perforate thickened posterior capsules.

Camptothecin induces protein-linked DNA breaks via mammalian DNA topoisomerase I

Camptothecin, a cytotoxic drug, is a strong inhibitor of nucleic acid synthesis in mammalian cells and a potent inducer of strand breaks in chromosomal DNA. Neither the equilibrium dialysis nor the unwinding measurement indicates any interaction between camptothecin and purified DNA. However, camptothecin induces extensive single strand DNA breaks in reactions containing purified mammalian DNA topoisomerase I. DNA breakage in vitro is immediate and reversible. Analyses of camptothecin-induced DNA breaks show that topoisomerase I is covalently linked to the 3' end of the broken DNA. In addition, camptothecin inhibits the catalytic activity of mammalian DNA topoisomerase I. We propose that camptothecin blocks the rejoining step of the breakage-reunion reaction of mammalian DNA topoisomerase I. This blockage results in the accumulation of a cleavable complex which resembles the transient intermediate proposed for eukaryotic DNA topoisomerase I. The inhibition of nucleic acid synthesis and the induction of DNA strand breaks observed in vivo may be related to the formation of this drug-induced cleavable complex.

Congenital cataract following German measles in the mother. Abstracts from the publications of the late Sir Norman McAlister Gregg

This paper contains abstracts from publications of the late Sir Norman McAlister Gregg, published in 1941 and 1944, in which he demonstrated the association between rubella in pregnancy and defects in the baby. Besides cataract and retinopathy with which ophthalmologists are familiar, there occur deafness, deafmutism, cardiac defects, mental retardation, pulmonary and renal abnormalities and diabetes.

Congenital ectropion uveae and glaucoma

Congenital ectropion uveae is a rare condition which may be present in one or both eyes. If the patient is followed glaucoma will always be found to be present. Associated features which have been described are ptosis, Rieger's anomaly, Prader Willi syndrome, facial hemiatrophy and neurofibromatosis. This paper describes a patient followed for 18 years who had bilateral congenital ectropion uveae, bilateral ptosis, asthma and late onset of a dental defect.

Sarcoidosis

(1) Sarcoidosis may affect any portion of the visual system. (2) Eye involvement may occur prior to, concurrent with, or after systemic manifestations. (3) Ocular manifestations may be the only complaint. (4) No age group is exempt. (5) Diagnosis may require a high index of suspicion. (6) Ocular sarcoidosis may be more common than is usually appreciated. (7) Ocular manifestations may be more common in black and oriental patients with sarcoidosis than in whites.