[Analysis of retinal nerve fiber layer thickness in superior segmental optic hypoplasia (SSOH)]

PURPOSE

To evaluate the clinical characteristics of patients with superior segmental optic hypoplasia (SSOH) and quantitatively assess the structural characteristics using optical coherence tomography (OCT).

METHODS

Forty-three eyes of 43 subjects with SSOH and 30 eyes of 30 normal subjects as controls (mean age; 40.2 +/- 14.1, 42.9 +/- 9.9 years, mean refraction; - 4.6 +/- 3.7 D, -3.6 +/- 2.7 D, mean intraocular pressure; 14.6 +/- 2.5 mmHg, 14.3 +/- 3.2 mmHg, Humphrey visual field mean deviation; -4.31 +/- 4.3 dB, 0.01 +/- 1.2 dB) were enrolled. Forty-three eyes of the 43 patients with SSOH were examined by OCT for the quantitative assessment of the RNFL thickness (RNFLT). For the comparison of RNFLT, total average thickness, four quadrants and clock hour-based (12 equal 30 degree sectors) RNFLT were analyzed using OCT.

RESULTS

OCT showed that the eyes with SSOH had significantly thinner RNFL than the normal subjects in total average thickness (SSOH 81.2 mm vs. 105.0 mm, p < 0.0001). Except for the temporal guadrant (p = 0.31), RNFL was thinner in superior, nasal(both p < 0.0001) and inferior (p = 0.002) guadrant. A comparison between the SSOH group and the normal control group for the 12 clock-hour segments in the OCT demonstrated that the patients with SSOH had decreased peripapillary RNFL thickness; the difference was statistically significant, except for the 7, 8, 9 and 10 o'clock segments. The area under the receiver operator characteristic curve (AUC) was greatest for the RNFL thickness of the 12 o'clock segment (AUC = 0.93), followed by the 1 o'clock segment (AUC = 0.90), and the 2 o'clock segment (AUC- = 0.87), as measured by the OCT.

CONCLUSIONS

More generalized thinning of the RNFL and decreasing total average thickness except for the RNFL from 7 o'clock to 10 o'clock were identified in the eyes with SSOH with a relatively superior entrance of the central retinal artery and thinning of the superior retinal nerve fiber layer. It was also demonstrated that segments 12, 1 and 2 o'clock of the SSOH were highly useful for differential diagnosis.

Studies on the uptake and release of fluoroquinolones by disposable contact lenses

PURPOSE

To evaluate the ability of three types of disposable contact lenses to take up and release three kinds of fluoroquinolones in vitro.

METHODS

We evaluated three FDA-approved disposable soft contact lenses (1-Day Acuvue, Medalist, and 14UV) for their ability to absorb and release three kinds of fluoroquinolones. Contact lenses were presoaked in fluoroquinolones for 1, 4, and 24 hours, and the uptake was determined by measuring the concentration of fluoroquinolones in the three types of disposable soft contact lenses by high pressure liquid chromatography (HPLC). After uptake, the lenses were placed in fresh saline baths, and release rates from the lenses were determined by measuring the concentration of fluoroquinolones in the saline baths by HPLC.

RESULTS

The disposable soft contact lens with the highest uptake of fluoroquinolones was the 1-Day Acuvue. After presoaking, drug concentrations in the 1-Day Acuvue and Medalist were higher than their theoretical saturation concentrations (i.e., the concentration of the fluoroquinolone eye drops [0.3%]). The release rates from the 1-Day Acuvue and Medalist lenses were slower than for the 14 UV lens.

CONCLUSIONS

These results indicate that among the lenses tested, the most practical drug delivery system is the 1-Day Acuvue disposable soft contact lens.

Identification of a mutated DNA ligase IV gene in the X-ray-hypersensitive mutant SX10 of mouse FM3A cells

The mouse carcinoma cell line SX10 is a hypersensitive mutant to x-rays and bleomycin. An earlier complementation test suggests that SX10 would belong to x-ray-cross complementing group (XRCC) 4. However, in this study, a human XRCC4 expression vector failed to complement the SX10 phenotype. Consistent with the previous report, SX10 showed the same level of DNA-dependent protein kinase activity as the wild-type SR-1. We isolated and analyzed hybrids between SX10 and human diploid fibroblast cells and found that human chromosome 13 conferred the x-ray resistance to the hybrids, suggesting that a candidate gene would be located on this chromosome. Polymerase chain reaction analysis with these hybrids and x-ray-resistant transformants obtained by introducing human chromosomes into SX10 indicated that the mutant was likely to be defective in DNA ligase IV. Sequence analysis of the DNA ligase IV gene confirmed that a defect in SX10 was attributed to a transition of G to A at nucleotide position 1413 of the gene, leading to an amino acid substitution from Trp at residue 471 to a stop codon. Revertant clones (Rev1-3) derived from SX10 showed a restored x-ray resistance; Rev1 reverted to the original nucleotide G at position 1413, whereas Rev2 and Rev3 to C. Transfection of a mouse DNA ligase IV cDNA vector into SX10 restored the resistance to both x-rays and bleomycin. SX10 showed a reduced frequency of chromosomal integration of transfected DNA, but the revertants restored the frequency found in the wild-type cells. These results suggest a possible involvement of DNA ligase IV in the integration event of foreign DNA as well as a crucial role in DNA double-strand break repair.

A novel UDP-sugar, UDP-3-ketoglucosamine or UDP-4-ketoglucosamine, from bovine heart muscle reduces metmyoglobin with NAD(P)H

3-Ketoglucose and similar ketosugars have been identified in microorganisms only and little is known about their functions. UDP-sugars are widely found as an intermediate in sugar metabolism in living organisms. Yet what role UDP-sugars play, or whether they play a direct role in metabolism, is still unknown. UDP-sugars were isolated and purified from bovine heart muscle, and a UDP-sugar fraction capable of NAD(P)H-dependent catalytic reduction of metmyoglobin was detected. Subsequent identification revealed that the active UDP-sugar was UDP-3- or UDP-4-ketoglucosamine. These compounds were purified from bovine cardiac muscle by ultrafiltration, anion-exchange column chromatography and reverse-phase chromatography. They were further characterized by determination of their chemical reducing activity, by comparison with synthetic UDP-3- or UDP-4-ketoglucosamine standards using high-performance liquid chromatography, by estimation of molecular mass using fast atom bombardment mass spectrometry, and by Fourier transform infrared microspectroscopy and electron probe microanalysis. The results suggest that UDP-3- or UDP-4-ketoglucosamine reduces metmyoglobin in bovine cardiac muscle. It is important that the reducing activity displayed by this ketosugar is not the effect of UDP-3- or UDP-4-ketoglucosamine alone but depends on NAD(P)H. In other words, this action of UDP-3- or UDP-4-ketoglucosamine is catalytic.

Acute retinal necrosis syndrome associated with herpes simplex keratitis

BACKGROUND

Although acute retinal necrosis (ARN) syndrome is caused by a herpes group virus, association of herpetic keratitis with ARN syndrome is uncommon. A case of unilateral ARN syndrome with herpes simplex keratitis is discussed.

METHODS

A 40-year-old man developed unilateral keratitis, necrotic retinitis, retinal vasculitis, vitritis, and iritis consistent with ARN syndrome 1 month after treatment for ipsilateral facial nerve palsy and auricular herpetic vesicles (Tolosa-Hunt syndrome). Impression cytologic examination of the corneal epithelial ulcer that developed concurrent with the intraocular findings and of the aqueous humor (obtained by paracentesis) was performed.

RESULTS

Cells that reacted with anti-herpes simplex virus type 1 (HSV-1) antibody were detected on impression cytology, and DNA fragments corresponding to the HSV-1 DNA sequence were detected in the aqueous humor.

CONCLUSION

This case shows that ARN syndrome may, on rare occasions, be associated with herpes keratitis secondary to HSV-1.

An atypical Leber's hereditary optic neuropathy with the 11778 mutation

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Triacylglycerol lipase-mediated release of arachidonic acid for renal medullary prostaglandin synthesis

The effect of triacylglycerol lipase or triarachidonin on the synthesis of prostaglandin E2 in rabbit kidney medulla slices was examined. Prostaglandin E2 generation was enhanced by exogenous triacylglycerol lipase, indicating that arachidonic acid released from medullary triacylglycerols is readily available for prostaglandin biosynthesis. Triarachidonin stimulated prostaglandin E2 production in a dose-dependent manner. Moreover, the kidney medulla slices showed triacylglycerol lipase activity using trimargarin as substrate. The addition of mepacrine made the stimulatory effect of triarachidonin on prostaglandin E2 formation more pronounced. Studies utilizing EGTA and p-bromophenacyl bromide revealed that triacylglycerol lipase of kidney medulla is independent of Ca2+ and sensitive to a sulfhydryl inhibitor. These results suggest the presence of triacylglycerol lipase and triacylglycerol as a possible candidate for providing free arachidonic acid to cyclooxygenase in kidney medulla.