Latanoprost and matrix metalloproteinase-1 in human choroid organ cultures.

PURPOSE: Latanoprost, a prostaglandin F2a analogue and ocular hypotensive agent, alters extracellular matrix and matrix metalloproteinases (MMPs), including MMP-1, within tissues of the uveoscleral outflow pathway. In addition to these tissues, the anterior choroid also is exposed to fluid within the uveoscleral outflow pathway. The present study was undertaken to compare MMP-1 expression in the choroid with other uveoscleral pathway tissues and to determine the effect of latanoprost on MMP-1 expression in human choroid organ cultures. METHODS: Choroid tissue explant cultures were generated and incubated with PhXA85, the biologically active form of latanoprost, or vehicle for 12 or 18 hours. Explant cultures from iris and ciliary body also were generated and exposed to PhXA85. Protein extracts of theses cultures, as well as from fresh tissues, were then probed for MMP-1 by Western blotting. All samples were normalized for protein content and reletive expression was evaluated by densitometry. Also, total RNA was harvested from fresh tissues or from cultures treated with PhXA85. The amount of MMP-1 mRNA in these samples was measured using real time polymerase chain reaction. These results were normalized according to simultaneous measurements of glyceraldehyde-3-phosphate dehydrogenase mRNA within the same samples. RESULTS: Compared to the ciliary body, in which specific MMP-1 concentration (/total mg protein) was greatest, the specific MMP-1 concentrations within iris, anterior choroid, and posterior choroid were less by 24.7 +/- 0.69%, 40.7 +/- 1.04%, and 64.5 +/- 0.52%, respectively (mean +/- SD). The order of MMP-1 mRNA expression among these tissues from fresh eyes was ciliary body < anterior choroid < posterior choroid < iris. Treatment of ciliary body explant cultures with 200 nM PhXA85 for 12 hours increased MMP-1 protein content by 154 +/- 34% (P = 0.004, students t test, N = 3). In contrast, similar treatment of anterior choroid, posterior choroid, or iris explant cultures minimally changed MMP-1 protein content (23 +/- 22+/-, P = 0.124; 14 +/- 8%, P = 0.462; 27 +/- 16%, P = 0.037, respectively). Increased MMP-1 was observed in choroid cultures incubated for 18 hrs with 200 nM or 500 nM PhXA85. MMP-1 mRNA in 12 hour PhXA85-treated choroid cultures was the same or less than vehicle-treated cultures from 7 of 9 donors. In contrast, MMP-1 mRNA was increased in PhXA85-treated ciliary body cultures from 2 of 2 donors. CONCLUSIONS: These results suggest that the capacity for latanoprost-mediated induction of MMP-1 within the choroid is less than within the ciliary muscle. Hence, it is unlikely that induction of MMP-1 in choroid plays as important a role in uveoscleral outflow modulation as induction of MMP-1 in the ciliary muscle.

Induction of tyrosinase gene transcription in human iris organ cultures exposed to latanoprost.

OBJECTIVE: Topical administration of latanoprost sometimes induces gradual iris darkening. The present study was undertaken to determine if latanoprost can increase transcription of the gene for tyrosinase, an important enzyme in the biosynthesis of melanin. Results from brown, hazel, and blue irides were compared. METHODS: Iris tissue was isolated from 30 pairs of postmortem human donor eyes, and 2 iris segments from each eye were incubated in tissue culture medium supplemented with 200nM latanoprost acid or vehicle for 7 days. Tyrosinase messenger RNA (mRNA) was determined using real-time polymerase chain reaction analysis (TaqMan quantitative polymerase chain reaction). Results for tyrosinase mRNA were normalized according to glyceraldehyde-3-phosphate dehydrogenase (GAPDH) mRNA in each sample. RESULTS: Tyrosinase mRNA expression was similar in blue and hazel irides, and ranged from 0.7-fold to 12.6-fold greater than GAPDH expression. In contrast, control brown iris culture tyrosinase expression ranged from 6.4-fold to 265-fold greater than GAPDH expression. Induction of tyrosinase mRNA by latanoprost was below threshold in all the blue iris cultures (n = 8 pairs), present in 1 of 9 hazel iris cultures, and present in 5 of 13 brown iris cultures. Mean induction in the responding hazel iris cultures was 1.40-fold. Mean induction among the responding brown iris cultures was 2.97-fold. CONCLUSIONS: These observations support the view that iris darkening associated with latanoprost treatment reflects induction of tyrosinase expression. Moreover, they suggest that the probability that latanoprost will increase tyrosinase expression is directly related to the magnitude of tyrosinase expression before treatments are initiated. CLINICAL RELEVANCE: The variability of iris darkening with latanoprost may reflect natural variation in the basal transcription of tyrosinase.

Design and outcomes of computer-based cognitive prosthetics for brain injury: a field study of three subjects.

Three traumatic brain injury (TBI) patients achieved a significant increase in level of function in a short period of time using a Computer-Based Cognitive Prosthesis (CBCP). A CBCP is a compensatory strategy which applies computer science concepts to brain injury rehabilitation. One-of-a-kind software is designed to assist the brain injury survivor in performing functional activities. New techniques of rehabilitation are also applied. Research subjects were between one and five years post injury. Patients were able to make substantial contributions to the design of their prosthetic software. Increases in level of functioning were seen both in everyday activities targeted for the intervention, as well as generalized increase on neurobehavioral and psychological dimensions.