Ocular fluid

The correlation (or lack of correlation) of other physiochemical characteristics has not yet been established. For instance, are all surfactants irritants Can one classify severity by the size of the molecule Can octanol water partition coefficients predict irritation potential does a propensity to partition out of the ocular fluid mean that a compound presents more of an irritation hazard than one which is more water soluble Theoretically, these data should reflect the ability of a compound to penetrate the eye and cause an irreversible lesion. However, until definitive data are available, physical and chemical parameters will probably have limited utility in an overall assessment of irritation. 

Subconjunctival injection-75 mg/0.25 ml injected subconjunctivally results in ocular fluid levels of antibiotic (lasting for 5 hours or more) with MICs sufficient for most susceptible pathogens. 

Aiello LP, Avery RL, Arrigg PG, Keyt BA, Jampel HD, Shah ST, Pasquale LR, Thieme H, Iwamoto MA, Park JE, Nguyen HV, Aiello LM, Ferrara N, King GL. 1994. Vascular endothelial growth factor in ocular fluid of patients with diabetic retinopathy and other retinal disorders. N Engl J Med 331 1480-1487. 

Solution, Gel Forming, Extended Release A solution that forms a gel when it comes in contact with ocular fluid, and which allows at least a reduction in dosing frequency. 

AieUo LP, Avery RL,Arrigg PG, et al. Vascular endothelial growth factor in ocular fluid of patients with diabetic retinopathy and other retinal disorders. N Engl J Med 1994 331 1480. 

Very high aqueous concentrations of sulfacetamide sodium (30%, pH 7.4) are nonirritating to the eye and are effective against susceptible microorganisms. The drug penetrates into ocular fluids and tissues in high concentrations (128). It is bound to plasma protein to the extent of 15 to 18% (4). The plasma half life is reported as 7 to 12.8 hours (129). 

Tainter 1938) and rabbits exposed to 0.25% 2,4-DNP in the diet for 8 hours (total dose 41 mg/kg) (Bettman 1946) did not develop cataracts. However, as discussed in Section 2.4 (Ocular Effects), cataracts were induced in rabbits injected intraperitoneally with 2,4-DNP (Gehring and Buerge 1969a). Immature rabbits (10 days old) were more susceptible than 62-day- old rabbits, while no cataracts were induced in 90-day-old rabbits. This age-related susceptibility to the cataract formation was attributed to a decreased ability to metabolize substances and an increased permeability of the blood-ocular fluid barrier in the very young rabbits. 

DNP, especially to the levels of the parent compound in the ocular fluid. Genetic factors may also play a role. 

Riegel, M. Ellis, P.P. High-performance liquid chromatography assay for antiinflammatory agents diclofenac and flurbiprofen in ocular fluids. J.Ckromatogr.B, 1994, 654, 140—145... 

This drug is a weak diuretic. In addition, it is useful in the therapy of glaucoma, as it reduces the formation of water in the ocular fluid. It is also useful in the therapy of metabolic alkalosis. Additionally, carbonic anhydrase inhibitors may also be useful in the therapy of hypooxygena-tion ( mountain sickness ), because they decrease alkalinization of the blood by increased excretion of bicarbonate, and in some types of seizures. 

Sulfacetamide is the N1-acetyl-substituted derivative o/sulfanilamide. Its aqueous solubility is 90 times that of sulfadiazine. This drug (isopto-cetamide, others) is employed extensively for ophthalmic infections. Very high aqueous concentrations are not irritating to the eye and are effective against susceptible microorganisms. The drug penetrates readily into ocular fluids and tissues. Sensitivity reactions to sulfacetamide are rare, but it should not be used in patients with known sulfonamide hypersensitivity. 

Methazolamide is a derivative of acetazolamide in which one of the active hydrogens has been replaced by a methyl group. This decreases the polarity and permits a greater penetration into the ocular fluid, where it acts as a carbonic anhydrase inhibitor, reducing intraocular pressure. Its dose for glaucoma is 50 to 100 mg two to three... 

Aminoglycosides are not well absorbed from the gastrointestinal tract but are well absorbed after intramuscular or subcutaneous injection. Effective concentrations are achieved in synovial, pleural, peritoneal, and pericardial fluids. Intrauterine and intramammary administration is also effective, but significant tissue residues result. Aminoglycosides do not bind significantly to plasma proteins, and as they are large polar molecules, they are poorly lipid-soluble and do not readily enter cells or penetrate cellular barriers. This means that therapeutic concentrations are not easily achieved in cerebrospinal or ocular fluids. Tlieir volumes of distribution are small, and the half-lives in plasma are relatively short (1-2 h). Elimination is entirely via the kidney. 

Penetrate cell membranes poorly or not at all limited or no significant absorption from GIT except for acid-stable aminopeni-cillins, which have moderate but species-variable absorption distribution limited mainly to extracellular fluids concentrations in intracellular fluid, CSF, miUc, and ocular fluids low, but effective concentrations may be reached in synovial, peritoneal, and pleural fluids some penicillins actively transported out of CSF into plasma generally excreted, usually in urine, in high concentrations as the parent molecule some drugs actively secreted into urine and/or bUe biotransformation (e.g., in the liver) usually slight or absent... 

Readily cross cell membranes generally moderate to good absorption from GIT but species-dependent effective concentrations achieved in intra- and transcellular as well as extracellular fluids except for poor penetration of sulfonamides into intracellular fluid due to acidic environment ability to penetrate into CSF and ocular fluids depends on plasma protein binding (e.g., most sulfonamides and diaminopyrimidines penetrate well) weak acids are ion-trapped in fluids alkaline relative to plasma, such as herbivore urine weak bases are ion-trapped in fluids acidic relative to plasma (e.g., prostatic fluid, milk, intracellular fluid, carnivore urine) commonly dependent on biotransformation for termination of activity but may also be excreted unchanged in urine and/or bile some drugs actively secreted into bile... 

Genetic hyperglycosaminoglycanuria is known to affect a number of the body fluids, including ocular fluids and cerebrospinal fluid, as was discovered at an early date. For example, dermatan sulfate and heparan sulfate occur in abnormally high levels in cerebrospinal fluid from cases of Hurler and Hunter syndromes (G21). 

Photons enter the eye through the cornea, pass through the ocular fluid that fills the eye, and fall on the retina. The ocular fluid is principally water, and passage of light through this medium is largely responsible for the chromatic... 

About 57 per cent of the photons that enter the eye reach the retina the rest are scattered or absorbed by the ocular fluid. Here the primary act of vision takes place, in which the chromophore of a rhodopsin molecule absorbs a photon in another n-to-n transition. A rhodopsin molecule consists of an opsin protein molecule to which is attached an 11-ds-retinal molecule (Atlas E3 and 3). The latter resembles half a carotene molecule, showing Nature s economy in its use of available materials. The attachment is by the formation of a proton-ated Schiff s base, utilizing the CHO group of the chromophore and the terminal NHj group of the side chain of a lysine residue from opsin (5). The free 11-ds-retinal molecule absorbs in the ultraviolet, but attachment to the opsin protein molecule shifts the absorption into the visible region. The rhodopsin molecules are situated in the membranes of special cells (the rods and the cones ) that cover the retina. The opsin molecule is anchored into the cell membrane by two hydrophobic groups and largely surrounds the chromophore (Fig. 12.52). 

Pherxsthiazine sulibxitle may permeate the ocular fluids and dermis, producing photophobia and photosensitization. 

Many polysaccharides contain branched structures and are chemically modified by the addition of other molecules. Their monomeric or repeat units are often made up of more than one sugar molecule and, consequently, can be quite complex. They form protective capsules of some of the most virulent microorganisms, capsules that, nevertheless, carry information that activate mammalian defenses the immune, interferon, and properdin systems [9, 136]. They are found as key portions of the exoskeletons of insects and arthropods and cell walls of plants and microbes and perform as reserve foodstuffs and important components of intercellular, mucous secretions, synovial and ocular fluids, and blood serum in many organisms. Food Applications compiles recent data on the food applications of marine polysaccharides from such various sources as fishery products, microorganisms, seaweeds, microalgae, and corals [137, 138]. One of the applications of this biopolymer relates to a method for protecting against diseases induced by Streptococcus pneumoniae infections, which comprises mucosal administration of a S. pneumoniae capsular polysaccharide to a patient in need. 

The site of origin of hyaluronic acid in the body is unknown. The presence of hyaluronate in ocular fluids and its absence from serum have been cited as evidence that it represents a secretion rather than a dialyzate (270). Meyer (264) has pointed out that the concept of synovial fluid as a dialyzate to which the mucin is added during passage through the connective tissue does not seem probable since, if such a mechanism exists, pleura and peritoneal fluid and lymph should likewise contain the mucin, which has not been shown to be the case. The fact that a viscous fluid appears in cultures of synovial tissue (426) was cited by him as evidence that hyaluronate is a secretory product of some cells of the synovial lining. This seems to be borne out by the fact that hyaluronic acid has been isolated from a synovioma, not only at the site of the tumor but in metastases in the liver (264). 

Now for that extraordinary and wonderful sense, vision. A lot of physics and physiology goes on between the object observed and the focus of its image on the retina of the eye, but the interface of the image with the brain is photochemical. About 57 per cent of the photons that enter the eye reach the retina the rest are scattered or absorbed by the ocular fluid, the fluid that Alls the eye and helps to maintain its shape. 

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