Identification of a novel water-soluble activator of wild-type and F508del CFTR: GPact-11a.

One of the major therapeutic strategy in cystic fibrosis aims at developing modulators of cystic fibrosis transmembrane conductance regulator (CFTR) channels. We recently discovered methylglyoxal alpha-aminoazaheterocycle adducts, as a new family of CFTR inhibitors. In a structure-activity relationship study, we have now identified GPact-11a, a compound able not to inhibit but to activate CFTR. Here, we present the effect of GPact-11a on CFTR activity using in vitro (iodide efflux, fluorescence imaging and patch-clamp recordings), ex vivo (short-circuit current measurements) and in vivo (salivary secretion) experiments. We report that GPact-11a: 1) is an activator of CFTR in several airway epithelial cell lines; 2) activates rescued F508del-CFTR in nasal, tracheal, bronchial, pancreatic cell lines and in human CF ciliated epithelial cells, freshly dissociated from lung samples; 3) stimulates ex vivo the colonic chloride secretion and increases in vivo the salivary secretion in cftr(+/+) but not cftr(-/-) mice; and 4) is selective for CFTR because its effect is inhibited by CFTR(inh)-172, GlyH-101, glibenclamide and GPinh-5a. To conclude, this work identifies a selective activator of wild-type and rescued F508del-CFTR. This nontoxic and water-soluble agent represents a good candidate, alone or in combination with a F508del-CFTR corrector, for the development of a CFTR modulator in cystic fibrosis.

A new long-chain UV absorber derived from 4-tert-butyl-4'-methoxydibenzoylmethane: absorbance stability under solar irradiation.

A new UV filter, the 1-(4-tert-butylphenyl)-2-decanyl-3-(4'-methoxyphenyl)-propane 1,3-dione called C10-DBM, was prepared by grafting a ten-carbon aliphatic chain to the alpha-carbonyl position of 4- tert -butyl-4'-methoxydibenzoylmethane (BM-DBM).(1) UVA absorption efficiency of a cosmetic preparation containing this new filter, called C10-DBM, was tested and compared to an identical preparation containing BM-DBM. The two preparations were irradiated under a 150-W xenon lamp or exposed to natural sunlight. The originality of this new filter resided in that its UVA absorbance appeared during the irradiation of the molecule. Moreover, although the molar absorption coefficient of C10-DBM in the UVA domain was lower than that of BM-DBM, its absorption showed much more photostable behavior under both methods of irradiation. After two hours of sunlight exposure, the preparation containing the BM-DBM lost 85% of its UVA absorbance, whereas the UVA absorbance of the preparation containing C10-DBM showed a decrease of 3% in comparison to the maximum absorbance obtained after 30 minutes of irradiation. Also, after two hours of exposure to natural sunlight, the UVA absorbance of the preparation containing C10-DBM remained above its initial value (before the irradiation began).

Influence of UVA pre-exposure on UVB-induced erythema. A chromometric study.

We examined the influence of ultraviolet A (UVA) pre-exposure on UVB minimal erythemal dose in 9 Caucasian subjects. Three zones were tested. One zone received only UVB, the second zone received a low UVA dose+UVB, and the third zone received a high UVA dose+UVB. Each zone was divided into 9 circles receiving increasing doses of UVB in order to obtain 3 different UVA-exposed series of 9 circles. Visual and chromometric readings were performed 24 h later. Pre-exposure to UVA caused variations in the slope of the dose-response curve (colorimetric index as a function of the UVB dose). In relation to UVB erythema, these variations indicated a protective effect for 6/9 subjects and an aggressive effect for 3/9 subjects. No predictive criteria were found for inclusion within a group.

Immediate pigment darkening: description, kinetic and biological function.

Immediate pigment darkening (IPD) is a transitory darkening of the skin observed after UVA exposure. The melanocytic system is implicated in its development. Indeed, it involves structural changes in melanocytes and keratinocytes and a chemical modification of pre-existing melanin. Darkening intensity is maximum immediately after exposure and decreases rapidly. The maximum efficiency wavelength for induction of IPD is around 340 nm. The phenomenon is inhibited by oxygen deprivation. Dose-response curves are linear for doses above 4 J/cm2. Minimum dose for induction of IPD (MIPDD) varies with the subject according to phototype, melanotype and skin color. The best criterion for predicting MIPDD seems to be chromametrically determined skin color. The biological role of IPD remains poorly understood; several hypotheses are discussed.

[Actinic erythema, false innocuousness of UV.A]. / Erythème actinique, fausse innocuité des UV.A.

The number of skin cancers is doubled every ten years. The responsibility of excessive sun exposure is incontestable as much for what concerns spino and baso cellular epitheliomas as for malignant melanomas. Over-exposure to ultraviolet B rays was considered as the determining cause of skin cancer and the entire prevention campaign was limited to the safeguard from these rays only. In reality, ultraviolet B rays are not uniquely responsible. Recent studies show that ultraviolet A rays, previously considered innocuous, are on the contrary aggressive as well and in a very deceiving way: it appears that it is the exposure to these rays in weak but repeated doses which are the most dangerous. It appeared that the visually determined value of MED was unchanged but the minimal dose responsible for color changes detectable with chromameter was decreased in the presence of UV.A for 3 subjects out of 4. This decrease was about 50% of the value obtained with UV.B alone. The strategy of protection needs to be completely reconsidered, particularly because today's lifestyle favors the exposition to ultraviolet A rays. There is an increase in exposure to UV.A rays when protection is limited only against ultraviolet B rays, giving a false sense of security especially to those who frequent tanning salons. It is therefore necessary to limit exposure time, use sunscreens protecting against not only UV.B, but also UV.A rays, and prohibit tanning salons. Public educational measures are inexistant, but should be introduced hastily in all public services.