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The eye of Aplysia has been used to explore various aspects of circadian rhythms. The authors discovered that age has profound effects on the circadian rhythm of nerve impulses from the eye. With age, there was a significant decrease in the amplitude of the rhythm. The decrease appeared to be continuous over the life span of the animal and was observed both in vitro and in vivo. The free-running period and phase angle of the rhythm steadily increased with age, indicating that the pacemaker itself was affected by age. Rates of transcription and translation were significantly increased with age, suggesting that age-associated alterations of the pacemaker may occur through changes in macromolecular synthesis. Interestingly, eyes from some older (> or = 10 months) animals had "cloudy" lenses (cataracts). Highly damped or arrhythmic rhythms always were seen in eyes with cloudy lenses. Morphology of eyes with cloudy lenses indicated severe retinal degeneration. No such degeneration was observed in eyes with clear lenses that were used in the analysis of the rhythm with age.

Visual diagnosis of second-degree burns has proven inadequate for determining the appropriate treatment regimen. Although multiple noninvasive imaging techniques have shown promise for providing information about burn wound severity, the ideal technology to aid burn wound excision would provide real-time readouts. Herein, the authors examine a high-resolution infrared (IR) camera (thermography) and a multiprobe adapter system (MPAS-6; transepidermal evaporative water loss, colorimetry) to assess their usefulness in predicting burn severity. Contact burn wounds of increasing severity were created in a porcine model. Wounds were assessed for 4 days with an IR camera and MPAS-6. In addition, each day, the burn wounds were biopsied for histological analysis to determine burn depth for correlation with noninvasive measures. Surface temperatures decreased with increasing burn severity, which was associated with increasing transepidermal evaporative water loss. Melanin content correlated with the depth of collagen coagulation and was bimodal, with superficial and full-thickness burns having higher values than deep partial thickness wounds. Erythema content was highest in superficial burns and negatively correlated with necrosis (high-mobility group box protein 1 expression). Importantly, surface temperature taken on every single day after injury was predictive of all histologically determined measurements of burn depth (ie, collagen coagulation, apoptosis, necrosis, vascular occlusion). The results indicate that IR imaging and skin quality probes can be used to support the diagnosis of burn severity. Most importantly, IR measurements gave insight into both the zone of coagulation and the zone of stasis on every postburn day studied.

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