Molecular basis for osmoregulation of organic osmolytes in renal medullary cells

The following proves that free radicals are involved in lead poisoning: An enolamine form of 5-aminolevulinic acid (ALA), a haem precursor which accumulates in the body of lead poisoned patients undergoes fast autooxidation with concomitant generation of reactive oxygen species. The transmembrane potential and calcium ions fluxes of isolated rat mitochondria are strongly affected by ALA. This toxic effect is inhibited by antioxidant enzymes. Induction of antioxidant enzymes' activity was observed in lead-exposed workers.     

Sensitivity loss and adaptation within the short-wavelength cone pathway

Two-color increment threshold data are used to develop a model of sensitivity control in short-wavelength detection. The model includes two sites of compressive nonlinearity. The first site has the characteristics of the S cones. Their output combines antagonistically with signals from the L and M cones at a second (blue/yellow opponent) stage. The response nonlinearities were examined by measuring thresholds for a 420-nm probe presented at the onset of flashed fields of 420-nm, 520-nm, and 580-nm light. Adaptive mechanisms of multiplication and subtraction were identified by presenting probe and flash on steady backgrounds of varying intensity. Adaptation partially restores the sensitivity lost to response compression.     

Thriving older African American women: aging after Jim Crow

Success of glaucoma filtration surgery is influenced by the wound healing response. Attention has been focused on pharmacological agents to control a process that leads to excessive scarring and eventual failure of glaucoma filtration surgery. Several agents, including 5-fluorouracil and mitomycin C, as well as other antiproliferative drugs will be discussed. Newer antifibrotic agents and novel drug delivery systems are under development in tissue culture and animal models in an effort to improve efficacy and safety. This article summarizes current treatment modalities and future prospects to prevent excessive wound healing and improve the success of glaucoma filtration surgery.     

The genetics of age-related macular degeneration

Age-related macular degeneration (ARM) is a progressive, chronic condition that results when the macula degenerates and central vision is lost. ARM is the leading cause of vision loss in Americans over age 50 and is a major public health concern. Very little is known about the etiology of ARM. Deciphering the genetic susceptibility associated with ARM holds great promise for gaining a better understanding of the disease, identifying at-risk individuals, and developing interventions and treatments.     

Model for ocular tear film function

Blepharitis patients have a number of disturbances in their tear film associated with meibomian gland dysfunction that affect evaporation and tear osmolarity. We tested a series of 156 consecutive patients, with a presumed diagnosis of blepharitis, dry eye, or allergic disease, and a series of 72 normals. We compared their tear film characteristics using tear osmolarity, tear volume, tear production (fluorophotometric and Schirmer test), tear turnover (decay constant), tear evaporation, and meibomian gland function evaluated by gland drop-out, expressed lipid viscosity, and volume. Of the 156 patients tested, we found 37 had dry eye, 10 had only allergic disease, 73 had meibomian gland dysfunction and dry eye, and 36 had only meibomian gland dysfunction. We created a model of the relative influence some of these factors had on each other using their correlation coefficients. The highest correlations for osmolarity were Schirmer test (-0.44), lipid volume low (-0.44), lipid viscosity high (0.39), gland drop-out (0.39), and tear evaporation (0.36). With regression analysis we accounted for 47% of the total variation in osmolarity, but only 17% of the variation in tear evaporation. We also present our classification system for blepharitis and dry eye patients based on our measurable physiologic parameters.