Ultradian rhythmicity of plasma cortisol is necessary for normal emotional and cognitive responses in man.

Glucocorticoids (GCs) are secreted in an ultradian, pulsatile pattern that emerges from delays in the feedforward-feedback interaction between the anterior pituitary and adrenal glands. Dynamic oscillations of GCs are critical for normal cognitive and metabolic function in the rat and have been shown to modulate the pattern of GC-sensitive gene expression, modify synaptic activity, and maintain stress responsiveness. In man, current cortisol replacement therapy does not reproduce physiological hormone pulses and is associated with psychopathological symptoms, especially apathy and attenuated motivation in engaging with daily activities. In this work, we tested the hypothesis that the pattern of GC dynamics in the brain is of crucial importance for regulating cognitive and behavioral processes. We provide evidence that exactly the same dose of cortisol administered in different patterns alters the neural processing underlying the response to emotional stimulation, the accuracy in recognition and attentional bias toward/away from emotional faces, the quality of sleep, and the working memory performance of healthy male volunteers. These data indicate that the pattern of the GC rhythm differentially impacts human cognition and behavior under physiological, nonstressful conditions and has major implications for the improvement of cortisol replacement therapy.

Quantitative cleaning efficacy evaluation methods with protein and lipid lens soiling models.

We developed a nondestructive, quantitative method for evaluating the cleaning efficacy of rigid gas permeable contact lens care systems. Simulated tears prepared with lysozyme, albumin, and calcium ions were applied to rigid gas permeable lenses as a protein soiling model, and a mixture of grease and unsaturated fat was applied as a lipid soiling model. The ComfortCare system (Pilkington Barnes Hind) and the Boston Cleaner and Boston Conditioning Solution (Polymer Technology) were evaluated for their efficacy in removing protein deposits; water was used as a control. The ComfortCare system and the Boston Advance Cleaner and Boston Advance Conditioning Solution were evaluated for their effectiveness in removing lipid deposits; saline was used as a control. Protein deposit level was detected by a densitometer at the absorbance of 280 nm. The lipid deposit level was evaluated by the absorbance of the fluorescence at 430 nm using the same densitometer with a fluorescence accessory. The two test systems demonstrated a significantly higher cleaning efficacy than the control for both soiling models. The methods provide quantitative measurements and therefore can be analyzed statistically for screening or comparison purposes.