New coaxial system for manual extracapsular cataract surgery.

A partially disposable coaxial system for manual extracapsular extraction is presented. This system provides for straight and curved irrigation/aspiration cannulas by means of a flexible outer sleeve. The elimination of a variety of connector tubings and nonluer-locked fittings has reduced intraoperative manipulations when compared to other partially disposable irrigation/aspiration systems.

SCE and UDS studies in a family with retinoblastoma: a case study.

The frequencies of both spontaneous and mitomycin C (MMC)-induced sister chromatid exchanges (SCE) were analyzed in mixed lymphocyte cultures from a kindred with retinoblastoma. Both the affected daughter and male proband, as well as two normal controls, were studied. No differences were observed in the spontaneous or in the MMC-induced SCE frequencies obtained from the peripheral lymphocytes of these patients compared to the normal controls. Unscheduled DNA synthesis (UDS) was observed in the lymphocytes treated with varying concentrations of both MMC and M-methyl-N-nitro-N-nitrosoguanidine (MNNG). Whereas no differences were observed in the rate of [3H]thymidine incorporation in the retinoblastoma-derived lymphocytes exposed to MMC when compared to the controls, differences were seen in the response to MNNG. Our data suggest that cells from these retinoblastoma patients respond like normal cells to damage induced by MMC, but that they are unable to repair damage induced by MNNG.

Increased serum levels of nerve growth factor in von Recklinghausen's disease.

Serum samples from patients with peripheral von Recklinghausen's disease were studied by competition radioreceptor assays and radioimmunoassays for biologically active 2.5S subunit of nerve growth factor (NGF). These specimens were fractionated at low pH to partially purify a 2.5S NGF-like activity that specifically competes for the binding of radioisotope-labeled 2.5S NGF to its receptor on human melanoma cells. In seven patients with peripheral neurofibromatosis, statistically significant elevations of this 2.5S NGF competing activity were found: approximately 85% of the patients tested had competing activities outside the 95% confidence limits of the normal population. No elevations of competing activity were observed when these serum fractions were examined by a specific radioimmunoassay for purified 2.5S NGF. These conflicting observations may suggest the existence of two molecular species demonstrating NGF-like activity: one sharing antigenic determinants with mouse 2.5S NGF and the other antigenically unrelated. We identified an NGF binding activity of high molecular weight in human serum. This activity is not elevated in the serum of patients with peripheral neurofibromatosis.

Epidermal growth factor receptors on corneal endothelium.

If a growth factor could bind to and stimulate human endothelial healing, corneal disease could be minimized. To this end, primary cultures of feline and human corneal endothelium were tested in receptor binding assays for radiolabeled epidermal growth factor (EGF). Both of these cells bound ten times as much 125I-EGF as did the negative control cell lines. The time course of association of 125I-EGF to cat corneal endothelium was found to be complete after approximately 120 minutes at 22 degrees C. The 125I-EGF was shown not to dissociate greatly when fresh binding buffer was added to endothelial cultures that had bound the radiolabeled peptide. The pH optimum for binding was determined to be approximately 6.4. The receptor number per cell and the affinity constant for binding were determined to be 40,000 receptors per cell and 1.1 x 10(9) L/mole, respectively, using a Scatchard plot. Parallel cultures of human fetal corneal endothelium grew in vitro only when the growth medium was supplemented with low concentrations of EGF. These studies provide evidence that EGF is specifically bound to the corneal endothelium.

Increased levels of a nerve-growth-factor cross-reacting protein in "central" neurofibromatosis.

Nerve-growth factor (N.G.F.) from serum was assayed in 9 affected individuals from three kindreds with the trait "central neurofibromatosis". The hallmark of this disease is bilateral acoustic neuromas. Antigenic activity, as measured by radioimmunoassay, was significantly elevated. However, functional activity for N.G.F.; as measured by radioreceptor assay, was normal or low. This indicates that the central form of neurofibromatosis is characterised by high circulating N.G.F. levels which show low to normal function. These changes in N.G.F. differ from those in peripheral neurofibromatosis and suggest that the two hereditary conditions involve different alterations in N.G.F. synthesis and/or regulation.

Nerve growth factor receptors on human melanoma cells in culture.

Purified mouse nerve growth factor (NGF)radiolabeled with 125I was tested for its ability to bind to a variety of different cultured cells. NGF binds readily to human and hamster melanoma cells but does not bind to many other cell lines. The three cell lines with the highest number of NGF receptors were derived from metastatic melanomas. One of these lines, A875, was studied in detail and was shown to have approximately 7x10(5) NGF receptors per cell with an association constant of 1.0x10(9) liters/mole. The use of these cells in competition binding assays permits the detection of 0.25 ng of NGF in various biologic fluids. NGF can be shown to increase the survival, but not the division, of melanoma cells maintained in medium depleted of serum growth factors. This effect of NGF as a specific "survival factor" appears analogous to its effect on cultured sympathetic ganglion cells and on other cells derived from the neural crest.