Vitreous humor, collection

Among the methods used, the determination of selected of analytes in vitreous humor (and of potassium in particular, based on the observation that its concentration progressively increases in this substrate after death) has been often adopted in the attempt to reduce imprecision of the estimate. Recently, for example, Munoz et al. [142] have developed an HPLC method for the determination of hypoxanthine, another substance whose concentration has been found to increase after death in vitreous humor. Separation was carried out under RP conditions using a mobile phase of KH2PO4 0.05M (pH 3) containing 1% (v/v) methanol at a flow rate of 1.5mL/min. UV spectra were recorded in the range 200-400 nm. Based on the analysis of samples collected at different PMIs, the authors found that about 53% of the variation in the data is explained by PMI. 

Hastings et al. [55] used this same in vitro technology to assess the enhancement delivery of dexamethasone using the Visulex iontophoretic system. The Visulex applicator and a freshly excised rabbit sclera were positioned between two halves of a side-by-side diffusion cell with the conjunctival side of the sclera facing the applicator (Figure 26.10). The donor drug solution (1 mg of dexamethasone phosphate) was present in the applicator, and diluted vitreous humor was modeled in the receptor cell. One milliampere direct current was applied for 60 min, and samples were collected during different treatment periods. It was demonstrated that the Visulex system produced a twofold increase in the amount of dexamethasone phosphate delivered after 60 min, compared with a standard iontophoretic administration (without the Visulex applicator). 

Visible Light - Visible is radiation with wavelength between 400 - 800 nanometer. Vitreous hemorrhage - A collection of blood within the vitreous humor. 

Various body fluids, in addition to blood and urine, are available in forensic autopsy cases. These fluids include cerebrospinal fluid, vitreous humor, pericardial fluid, and bile. Samples can be collected with disposable syringes, with or without needles, and transferred to glass containers (5-10 ml) containing sodium fluoride at a final concentration of 1-2% as a preservative. As samples from living persons, the containers should be preserved at 4°C until analysis. Special care should be taken while testing for ethanol in postmortem samples since intestinal bacteria diffuse through the body after death via vascular system and induce putrefaction. In moderate to heavily... 

Heroin or its metabolites have been identified in various biological matrices including plasma, urine, and saliva collected from human subjects administered heroin hair and sweat collected from heroin users urine, vitreous humor, and cerebrospinal fluid collected from cadavers whose death was due to narcotic intoxication and meconium collected from infants with prenatal exposure to heroin. Frequently, only morphine is assayed because of the instability of heroin and 6-acetylmorphine in blood, plasma, and... 

Vitreous humor The vitreous humor (VH) from the eyes of female rabbits is used as culture medium for nuclear donors and manipulated embryos (Collas and Robl, 1991). Aseptically collect VH by puncturing the eyes of euthanized female rabbits aspirate 1 to 1.5 ml of VH from each eye with a 3-ml syringe with 18-gauge needle. Immediately centrifuge the fluid at 15,000 g for 2 min to pellet cellular debris and filter (0.2 m) the supernatant in 50- to 100-/tl drops immediately overlaid with mineral oil in a 60 x 15-mm plastic petri dish. Incubate dishes at 37°C in a humidified atmosphere of 7% CO2 in air 12-24 hr prior to culturing embryos. 

Bothaqueousand vitreous humor are usefrd, but should be collected separately... 

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