Fibronectin concentration in tears of contact lens wearers

The tears of soft contact lens wearers (wearing lenses on an extended were schedule) were analysed for the amount of fibronectin, albumin and total protein. Tears were collected during the day without stimulation and the levels were then compared to levels in non-contact lens wearers tears. The level of fibronectin in the tears of contact lens wearers (120 ng ml-1) was significantly higher than in the tears of non-contact lens wearers (21 ng ml-1; P < 0.01). There were no differences in the amount of albumin or total protein. When contact lens wearers were divided into those subjects who carried significant levels of bacteria on their contact lenses and non-carriers, the amount of fibronectin and albumin was found to be higher in the tears of bacterial carriers (P < 0.03), whereas the amount of total protein remained the same. The fibronectin in the tears and on the contact lens may predispose subjects to contamination by bacteria and thus increase the risk of inflammatory or infectious diseases associated with bacterial contamination of contact lenses.

Fibronectin in the tear film

PURPOSE

Fibronectin plays an important role in corneal healing and has been detected previously in the tear film. To investigate the levels of fibronectin in normal human tears, the authors measured and compared fibronectin concentration in open-eye, closed-eye, and reflex tear fluid. The origin of fibronectin in the tear film was investigated by comparing fibronectin concentration in sequentially collected reflex tear samples with the concentrations of total protein and albumin in the same samples.

METHODS

Open-eye and closed-eye tears were collected from 11 noncontact lens wearers. From 7 subjects, 20 uninterrupted reflex tear samples (10 microliters each) subsequently were collected, using the sneeze reflex method of stimulation, followed by an additional 10 nonstimulated tear samples (3 microliters each) immediately after cessation of stimulus. Enzyme-linked immunosorbent assays were used to determine fibronectin and albumin concentrations, and bicinchoninic acid protein assays were used to determine total protein concentration in each sample.

RESULTS

Fibronectin concentration in open-eye tears (19 +/- 24 eta g/ml, range 3 to 78 eta g/ml) was significantly different (P = 0.004) from that in closed-eyes tears (4127 +/- 3222 eta g/ml, range 1177 to 11384 eta g/ml). In the first 50 microliters of reflex tears, fibronectin concentrations were low (10 +/- 23 eta g/ml), but they increased significantly (P = 0.028) after 100 microliters of reflex tears had been collected (220 +/- 126 eta g/ml). There was a further marked transient increase (767 +/- 946 eta g/ml) after cessation of stimulus. Total protein concentration in the same samples decreased significantly during reflex tear collection compared to open-eye tears, and it increased gradually after cessation of stimulus. Albumin concentration in the same samples, analyzed for two subjects only, showed a pattern similar to that for fibronectin. Dilation of conjunctival blood vessels was noted in all subjects after reflex tear collection. Administration of a topical vasoconstrictor in two subjects eliminated the increase in fibronectin concentration during reflex tearing but did not affect total protein concentration. Under reducing conditions, the molecular mass of fibronectin in open-eye and reflex tears was 240 kDa, identical to commercially available purified plasma fibronectin, whereas fibronectin in closed-eye tears was degraded into small molecular mass fragments.

CONCLUSIONS

These findings suggest that fibronectin in tear fluid is derived from plasma and that the increase in concentration in closed-eye and reflex tear fluid is caused by leakage from dilated conjunctival blood vessels.

Gram-negative bacteria can induce contact lens related acute red eye (CLARE) responses

PURPOSE

Twelve volunteers participated in a study designed to measure the overnight corneal edema response with a variety of hydrogel contact lenses. During the study four subjects (5 eyes) experienced a contact lens related acute red eye (CLARE) reaction, which manifested as severe ocular pain, photophobia, corneal infiltration, and conjunctival hyperemia. An additional five subjects (7 eyes) developed corneal infiltrates only. Twelve eyes (of 9 subjects) showed no response.

METHODS AND RESULTS

Upon microbiological examination of the contact lenses and storage solutions, gram-negative bacteria were isolated in large amounts. The bacteria were identified as Serratia marcescens, Pseudomonas putida, and Pseudomonas aeruginosa. Significantly greater numbers of bacteria were isolated from contact lenses of subjects who experienced CLARE than from the other subjects (P = 0.005) and from the contact lenses of subjects who experienced an adverse reaction (CLARE or infiltrates) than from the other subjects (P < 0.001). The contaminating bacteria are thought to have been introduced to the lens storage vials as a result of lens handling and subsequent failure to disinfect lenses.

CONCLUSIONS

This study draws attention to the possible contribution of contaminated lenses and storage cases in contact lens related acute inflammation and specifically implicates gram-negative bacteria, in particular Pseudomonas spp. and Serratia spp., in the inducement of acute inflammatory reactions such as CLARE.

Simultaneous quantitation of indole 3-acetic Acid and abscisic Acid in small samples of plant tissue by gas chromatography/mass spectrometry/selected ion monitoring

Indole 3-acetic acid (IAA) was analyzed in apple, orange, and prune tissue by GC-MS by monitoring the protonated molecular ion of its methyl ester at mass to charge ratio (m/z) 190 together with the major fragment ion at m/z 130 and the corresponding ions from the methyl esters of either [(2)H(4)]IAA (m/z 194, 134) or [(2)H(5)]IAA (m/z 195, 135). Abscisic acid (ABA) was analyzed by monitoring the major fragment ions of its methyl ester at m/z 261 and m/z 247 and the corresponding ions from the methyl ester of [(2)H(3)]ABA (m/z 264, 250). Detection limits for IAA and ABA were 1 and 10 picograms, respectively using standards and 1 nanogram per gram dry weight for both phytohormones in plant tissue.