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Biomedical subjects

N L Robinson

Publications and source records attributed to N L Robinson.

32 records · Page 2Linked to original sources

Regulation of ADPGlucose Synthesis in Guard Cells of Commelina communis.

The activator specificity of the ADPglucose pyrophosphorylase from Commelina communis guard cells is the same as observed for the mesophyll cell enzyme. 3-Phosphoglycerate was found to be the most effective activator. Fifty per cent of maximal stimulation was observed at about 100 micromolar. Inorganic phosphate was found to be a potent inhibitor giving 50% inhibition at 0.3 millimolar. These results are discussed with respect to regulation of starch synthesis in guard cells.

Journal Article↗

Capillary endothelial cell migration: stimulating activity of aqueous humor from patients with ocular cancers.

In double-masked studies, various concentrations of aqueous humor (AH) from 157 patients (208 samples) with ocular cancers, nonmalignant ocular lesions, and normal eyes were added to bovine capillary endothelial (BCE) cells plated onto gold-coated cover slips. The phagokinetic tracks made by 100 cells at each concentration were traced, and the mean area of migration plus or minus the standard error of the mean was determined. Data are expressed as the percentages of increase in mean track area made by 100 cells incubated in medium that contained AH samples beyond the mean area of 100 cells incubated in medium alone. The percentage increases in migration-stimulating activity were as follows: a) malignant ocular disease--retinoblastoma (30 samples), 34 +/- 2; malignant melanoma (55 samples), 37 +/- 3; b) nonmalignant ocular disease--cataracts, glaucoma, pseudoglioma, and diabetic retinopathy (36 samples), 14 +/- 2; c) control AH--no ocular disease (51 samples), 9 +/- 1; normal eyes and systemic cancer (36 samples), 38 +/- 6. The percentage increase in endothelial cell migration was as great in cases of systemic cancer as it was in cases of ocular cancer. The endothelial cell migration-stimulating activity in AH from patients with intraocular cancers was significantly higher than the levels in the other groups of patients having no systemic cancer (P much less than .001). In addition, when the results were compared in the control group and the group with benign ocular disease, no significant differences were detected (P greater than .01).

Animals↗

Uveal tuberculosis.

Ocular tuberculosis should be considered in the differential diagnosis of panophthalmitis, uveitis, and intraocular neoplasms. We have presented 6 cases illustrating some of the clinical and pathological characteristics of two types of ocular involvement, acute tuberculous panophthalmitis and ciliary body tuberculoma. The former should be entertained when panophthalmitis or uveitis occur in debilitated patients with obvious systemic tuberculosis foci. Ciliary body tuberculoma should be suspected in relatively healthy individuals with a history of tuberculosis and an intraocular mass. The diagnosis is confirmed by positive cultures or the identification of the organism by acid-fast stains. Typical histopathology in the appropriate clinical setting is sufficient to start specific antituberculous therapy, which should be used in all cases.

Adolescent↗

Retinoblastoma and angiogenesis activity.

Aqueous humor from 30 enucleated retinoblastoma-bearing eyes and 9 cell cultures of retinoblastoma were tested for angiogenesis activity using capillary endothelial cell migration assays. Aqueous from 90% of retinoblastoma eyes stimulated endothelial cell migration, compared with 25% of control eyes. Five of nine retinoblastoma cultures stimulated endothelial cell migration and five showed chorioallantoic membrane (CAM) neovascularization when compared with positive controls for angiogenesis activity. These results suggest an inverse relation between the length of time in culture and the ability of these cells to stimulate angiogenesis using these assays. Cells in culture for short periods of time gave positive test results, whereas continuous cell lines of retinoblastoma were consistently negative. While aqueous humor from retinoblastoma-bearing eyes demonstrated significant angiogenesis activity, cultured retinoblastoma cells show this only in early passages. Several possible explanations for this are considered.

Aqueous Humor↗