Biomedical subjects
Publications and source records attributed to S Roh.
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The effects of light on the eye are being increasingly recognized. In addition to visible radiation, we are constantly exposed to infrared and ultraviolet radiation throughout life. Acute light damage such as sunburn of eyelids, photokeratitis and solar retinopathy are well recognized and fairly obvious. The effects of chronic light exposure have been more controversial. Recent epidemiologic studies are showing an association between long-term sunlight exposure and ocular diseases such as cataracts, age-related macular degeneration, pterygium and climatic droplet keratopathy. Furthermore, the role of photosensitizers contributing to light-induced ocular damage needs to be kept in mind. The ocular hazard from photosensitizing drugs and sunlight in general is greatest in aphakic eyes that have lost their natural ultraviolet filter (the ocular lens) and in young children, whose own lenses readily transmit ultraviolet light. At present, there is enough evidence to assume that chronic sunlight exposure contributes to ocular disease and to institute preventive measures.
Restriction of dietary calorie intake is associated with life extension and with the delay of age-related disorders. Preliminary studies demonstrated that by feeding the Emory mouse a diet restricted by 21% in calories cataract and insolubilization of protein could also be delayed. To observe the effects of calorie restriction over prolonged portions of adulthood, Emory mice were fed the control diet (C) or a diet restricted by 40% in calories (R). Feeding the R diet was associated with delayed formation or progress of cataract over virtually the entire second half of life. At 11 months of age, bilateral grade 5 cataracts were present in 17% and 2% of C and R lenses, respectively. At 22 months of age, bilateral grade 5 cataracts were present in 90% and 18% of C and R lenses, respectively. The distribution of alpha-, beta-, and gamma- crystallins in the water-soluble, urea-soluble, and SDS-soluble fractions indicates more similarities than differences between C and R lenses with a specific grade of cataract or of a given age. However, there were significant and abrupt (after grade 4 cataract) losses of particular gamma-crystallins; gamma-crystallins which were not prominent at earlier stages became the major gamma-crystallin moieties. Losses of alpha-crystallins were also noted upon cataract formation or aging in most of the fractions. Aggregates including gamma- and alpha-crystallins also accumulate faster in the C group.
Catechol 2,3-dioxygenases were cloned from Alcaligenes sp. KF711, Pseudomonas putida KF715, and Achromobacter xylosoxidans KF701 which are biphenyl/polychlorinated biphenyls-degrading bacteria. All of the cloned enzymes were purified by preparative polyacrylamide gel electrophoresis (PAGE). The purified catechol 2,3-dioxygenases were significantly different from one another in ring-fission activities to catechol and its derivatives. The catechol 2,3-dioxygenase from Alcaligenes sp. KF711 exhibited higher ring-fission activity to 4-chlorocatechol than those from P. putida KF715 and A. xylosoxidans KF701. In electrophoretic mobilities, the three enzymes were different from one another on nondenaturing PAGE but the same on SDS-PAGE.
DNA (herpes viruses) and RNA (rubella, rubeola) group viruses are recognized causes of viral retinitis. Severe damage is often the result, not only because the viruses have a cytologic effect but also because the antigens may cause immune complex deposition that results in vasculitis. Most of the viral retinitides are associated with systemic disease; immune-compromised individuals are more susceptible than healthy individuals. A distinct clinical entity, acute retinal necrosis, affects the eye only in healthy individuals and is associated with the herpes family of viruses.
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This study was aimed to verify the debridement potential of the Caridex system against radicular cervical caries. 14 freshly extracted teeth with cervical caries were split and the fragments were freed from the dentinal caries using three methods: root planning (with a white stone), conventional excavation with a bur (tungsten) and the Caridex system. The results show that the Caridex system can partially dissolve the decayed dentin but leaves behind smeared surfaces as well as part of dentin infiltrated by bacteria. The root planning treatment smears the dentinal surface and thus blocks the tubules which also appeared to be infiltrated with bacteria. The excavation method allowed for a complete elimination of the decayed dentinal tissue down to the hypermineralized zone.
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