Natural moisturizing factor (NMF) of the stratum corneum (SC) has been established to play important roles in the physical properties of the SC. Few studies, however, have investigated the specific influences of NMF components other than the amino acids. In this study, therefore, we focus on the relationship between the ion content and physical properties of the SC in 40 healthy subjects. Changes in the physical properties of the SC induced by the extraction of NMF were equivalent to the changes that took place from summer to winter, demonstrating the important role of NMF in the physical properties of the SC in healthy subjects. The seasonal changes in the physical properties of the SC from summer to winter were accompanied by significant decreases in the levels of lactate, potassium, sodium, and chloride in the SC. Lactate and potassium were the only components found to correlate significantly with the state of hydration, stiffness, and pH in the SC. Interestingly, the levels of lactate and potassium in the SC were also significantly correlated. Moreover, potassium lactate restored the SC hydration state decreased by extraction of NMF. These results suggest that lactate and potassium may play roles in maintaining the physical properties of the SC in healthy subjects.

Even though the skin surface is acidic (about pH 5), most in vitro studies on desquamation have been performed at alkaline pH. We demonstrate that the standard in vitro model system, which achieves squame shedding upon incubation of plantar stratum corneum for 1 day in an alkaline buffer that must include a chelating agent, can be extended to a more realistic model in which the incubation is for 4 days, at varying pHs from 5 to 8, without exogenous chelators. Desmoglein I from stratum corneum was degraded by the squames shed at pH 5 as well as at pH 8. Squame shedding was inhibited to varying extents by the addition of proteinase inhibitors, whose specificity suggested that the crucial enzymatic activity at pH 8 was a chymotrypsin-like serine proteinase, while a similar activity at pH 5 was accompanied by an aspartic proteinase activity of comparable strength. Four degradation peaks were observed when the insulin B chain was reacted with shed squames at pH 5. Two of these peptides were suppressed by the addition of phenylmethylsulphonyl fluoride, the other two by pepstatin A; chymostatin inhibited all four, but E-64 and leupeptin showed no effect. The implied specificity was confirmed by reacting the insulin (without squames) with the standard enzymes human liver cathepsin D and pancreatic chymotrypsin, reproducing the expected degradation products. These results suggest that epidermal desquamation at acidic pH requires two proteolytic activities, one of which is an analogue of chymotrypsin and the other of cathepsin D. Endogenous proteinases corresponding to these activities have been previously identified, namely the stratum corneum chymotryptic enzyme and the mature active form of cathepsin D.

Brown adipose tissue (BAT) is responsible for cold-and diet-induced thermogenesis, and thereby contributes to the control of whole-body energy expenditure (EE) and body fat content. BAT activity can be assessed by fluoro-2-deoxyglucose (FDG)-positron emission tomography (PET) in human subjects. Grains of paradise (GP, Aframomum melegueta), a species of the ginger family, contain pungent, aromatic ketones such as 6-paradol, 6-gingerol and 6-shogaol. An alcohol extract of GP seeds and 6-paradol are known to activate BAT thermogenesis in small rodents. The present study aimed to examine the effects of the GP extract on whole-body EE and to analyse its relation to BAT activity in men. A total of nineteen healthy male volunteers aged 20-32 years underwent FDG-PET after 2 h of exposure to cold at 198C with light clothing. A total of twelve subjects showed marked FDG uptake into the adipose tissue of the supraclavicular and paraspinal regions (BAT positive). The remaining seven showed no detectable uptake (BAT negative). Within 4 weeks after the FDG-PET examination, whole-body EE was measured at 278C before and after oral ingestion of GP extract (40 mg) in a single-blind, randomised, placebocontrolled, crossover design. The resting EE of the BAT-positive group did not differ from that of the BAT-negative group. After GP extract ingestion, the EE of the BAT-positive group increased within 2 h to a significantly greater (P,0·01) level than that of the BAT-negative group. Placebo ingestion produced no significant change in EE. These results suggest that oral ingestion of GP extract increases wholebody EE through the activation of BAT in human subjects.Key words: Grains of paradise: 6-Paradol: Brown adipose tissue: Energy expenditure Brown adipose tissue (BAT) is the major site for sympathetically activated thermogenesis during cold exposure and spontaneous overfeeding, at least in small rodents (1) . Recent studies using fluoro-2-deoxyglucose (FDG)-positron emission tomography (PET) combined with computed tomography (CT) have revealed the existence of metabolically active BAT in adult human subjects (2 -4) . It is now established that, in healthy adults, BAT is activated by acute cold exposure and significantly contributes to cold-induced thermogenesis (2 -5) . It has also been demonstrated that the prevalence and activity of BAT are lower in subjects with higher adiposity, being negatively correlated with BMI, body fat content and visceral fat (2,3) . Moreover we found that the prevalence of BAT decreased with age, being more than 50 % in the twenties, but less than 10 % in the fifties and sixties, and that decreased BAT activity is associated with age-related accumulation of body fat (6) . It is thus likely that BAT, based on its thermogenic activity, contributes to the control of whole-body energy expenditure (EE) and body fat metabolism in human subjects, as established in small rodents, and thereby is a promising target for interventions to prevent and treat obesity. A number of food ingredients have been p...

Ultraviolet light (UV) radiation causes skin-tanning, which is thought to be mediated by stimulating the release of melanogenic factors from keratinocytes as well as other cells. Nitric oxide (NO) has been reported to be generated after UV radiation and to stimulate melanocytes as one of the melanogens. In a previous experiment by another group on melanogenesis induced by NO, increases in both tyrosinase activity and tyrosinase protein levels were observed after daily stimulation of NO for 4 days. In the present study, we investigated tyrosinase gene expression within the first 24 hr of NO-induced melanogenesis. Tyrosinase mRNA expression was found to be induced 2 hr after a single treatment with S-nitroso-N-acetyl-L-arginine. An increase of tyrosinase activity was also detected time-dependently within the 24-hr period, accompanied by an increase of tyrosinase protein levels. The induction of mRNA expression was suppressed by a cyclic guanosine 3',5'-monophosphate (cGMP)-dependent protein kinase (cGMP/PKG) inhibitor. These results suggest that the enhancement of tyrosinase gene expression via the cGMP pathway may be a primary mechanism for NO-induced melanogenesis.

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