Choroid

Chorionic tissue Choroid C18H30O6S C28H4406S2 C2H60S C7H803S C8H20O4S1 C32H6404Sn C36H70O4Zn Christiansen colors... 

Zinc. The 2—3 g of zinc in the human body are widely distributed in every tissue and tissue duid (90—92). About 90 wt % is in muscle and bone unusually high concentrations are in the choroid of the eye and in the prostate gland (93). Almost all of the zinc in the blood is associated with carbonic anhydrase in the erythrocytes (94). Zinc is concentrated in nucleic acids (90), and found in the nuclear, mitochondrial, and supernatant fractions of all cells. 

Vision is vital for human activities, and eyes are very sensitive to a number of toxic insults induced by chemical compounds. The most serious outcome is permanent eye damage which may be so severe as to cause loss of vision. The eye consists of the cornea and conjunctiva, the choroid, the iris, and the ciliary body. It also contains the retina, which is of neural origin, and the optic nerve. The retina contains photoreceptors, a highly specific light-sensitive type of neural tissue. The eye also contains the lens and a small cerebrospinal fluid system, the aqueous humor system, that is important for the maintenance of the steady state of hydration of the lens and thus the transparency of the eye. 

Ader, /. vein (in various senses) (Elec.) wire, strand, -chen, Aderchen, n. little vein, vein-let. -haul,/, choroid. hautchen,n. chorion. holz, n. wood cut with the grain, aderig, aderig, a. veiny, veined, streaked venous, vascular. 

Venen-blut, n. venous blood, -hfiutchen, n, choroid membrane, -stein, m. vein stone, phlebolite. 

Disorder characterized by atrophy ofthe choroid (the thin membrane covering most of the posterior of the eye between the retina and sclera) and degeneration of the retinal pigment epithelium resulting in night blindness. The disease is caused by mutations in Rab escort protein Repl (component A of Rab geranylgeranyl transferase). 

Localization CNS Cortex, hippocampus, striatum, olfactory bulb, spinal cord CA/S not present in adult. CNS Choroid plexus, medulla, pons, striatum, hippocampus (CA1, CA3), hypothalamus, spinal cord CNS Striatum, hippocampus (CA1), substantia nigra, globus pal-lidus. CNS Striatum, brainstem, thalamus, hippocampus, olfactory bulb, substantia nigra... 

While most investigations show that sea snake neurotoxins are postsynaptic type, Gawade and Gaitonde (23) stated that Enhydrina schistosa major toxin has dual actions or postsynaptic as well as presynaptic toxicity. E, schistosa venom phospholipase A is both neurotoxic and myotoxic. Neurotoxic action of the enzyme is weak so that there is sufficient time for myonecrotic action to take place (24), Sea snake, L. semifasciata toxin also inhibits transmission in autonomic ganglia, but has no effect on transmission in choroid neurons. 

Melanins are prodnced in mammals in two types of cells of different developmental origin (1) the melanocytes of the skin, hair, choroids and iris and (2) the retinal pigment epithelium (RPE). Specialized organelles of the melanocytes, the melano-somes, synthesize and store eumelanins and phaeomelanins. 

The retina comprises two principal components, the non-neural retinal pigment epithelium and the neural retina. The retinal pigment epithelium is an essential component of the visual system both structurally and functionally. It is important for the turnover and phagocytosis of photoreceptor outer segments, the metabolism of retinoids, the exchange of nutrients between the photoreceptors, and the choroidal blood vessels and the maintenance of an efficient outer blood-retinal barrier. 

Elliott et al. utilized a clenbuterol immunoassay to determine clenbuterol residues in cattle tissues and fluids. The LOD was 0.25 ug for liver. Animals were dosed with medicated feed (1.6 ug kg per day), and pairs were slaughtered during the medication phase and at 14,28, and 42 days after withdrawal. Clenbuterol concentrations in liver and retina/choroid samples were confirmed by GC/MS. Correlation coefficients between the ELISA and GC/MS were = 0.92 for retina/choroid samples and... 

Early macular changes are often called age-related macu-lopathy and are characterized by large drusen and pigmentary abnormalities in the macula.20 Age-related maculopathy accounts for 85% to 90% of all age-related macular changes. Ten to fifteen percent of these patients will develop advanced atrophy and/or develop abnormal blood vessels in and under the retina called choroidal neovascular membranes. Patients are then classified as having AMD.23... 

Drusen ablation may help patients with multiple large drusen in both eyes that have not progressed to neovascular macular degeneration. These laser treatments may lead to resolution of the drusen and improved visual acuity. However, it is not clear if progression to choroidal neovascular membranes and neovascular macular degeneration is reduced.23 There is a possibility that the laser treatments may induce choroidal neovascularization and retinal atrophy.22... 

Choroidal neovascular membranes Development of abnormal blood vessels in and under the retina. 

Uveitis An inflammation of the uvea in the eye. Uveal structures include the iris, the ciliary body, and the choroid. 

Elimination from the vitreous occurs by one of two pathways. This can be visualized by injecting fluorescent compounds and examining the concentration distribution in frozen sections obtained after a steady state has been established [230]. If the major route of elimination is by means of the re-tina/choroid, at steady state the lowest concentration would be in the vicinity of the retina. The contours observed in frozen sections of the rabbit eye obtained after intravitreal injection of fluorescein exhibit this pattern, with the highest concentration immediately behind the lens (Fig. 16A). Compounds not chiefly eliminated through the retina exit the vitreous by passive diffusion and enter the posterior aqueous, where they are eliminated by the natural production and outflow of aqueous humor. In such a situation, the contours would be perpendicular to the retina, with the highest concentration towards the rear of the vitreous cavity. This appears to be the case for fluorescently labeled dextran polymer, whose contours decrease in concentration toward the hyaloid membrane (Fig. 16B). 

Kidney glomeruli, GI tract mucosa, exocrine and endocrine glands, certain tumors, pertibular capillaries, choroid plexus, pancreas, intestinal wall Sinusoidal... 

Izumi-Nagai, K., N. Nagai et al. (2007). Macular pigment lutein is antiinflammatory in preventing choroidal neovascularization. Arterioscler. Thromb. Vase. Biol., Oct. 11 [Epub ahead of print]. 

The presence of only two dietary carotenoids in the retina, lutein and zeaxanthin, out of about 14 normally present in the plasma indicates their highly specific uptake and retention (Bernstein et al., 2001 Bone and Landrum, 1992 Bone et al., 1988,1997,1993 Davies and Morland, 2004 Khachik et al., 1997, 2002). The retina-blood barrier is formed by the tight zonulae occludentes of the endothelial cells in the inner retina and of the RPE, a monolayer of cells which separates the outer retina from its choroidal blood supply (Strauss, 2005). 

ApoC-I is expressed mainly in liver but also in lung, skin, testis, spleen, neural retina, and RPE. Its multiple functions include the activation of lecithin cholesterol acyltransferase (LCAT) and the inhibition, among others, of lipoprotein and hepatic lipases that hydrolyze triglycerides in particle cores. Notably, both LCAT and lipoprotein lipases are expressed in RPE and choroid (Li et al., 2006). Moreover ApoC-I has been shown to displace ApoE on the VLDL and LDL and thus hinder their binding and uptake via their corresponding receptors (Li et al., 2006). 

The expression of all these apo-lipoproteins by the RPE, and its ability to form lipoprotein particles suggest that these newly formed lipoproteins may be involved in the transport of lipophilic molecules, including carotenoids, from the RPE to the neural retina and/or to the choroidal blood supply. Testing the roles of apolipoproteins and lipoprotein particles in carotenoid secretion from the RPE is another subject awaiting experimental investigation. 

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