Identifying reliable ions for the statistical differentiation of structurally similar fentanyl analogs.

Definitive identification of fentanyl analogs based on mass spectral comparison is challenging given the high degree of structural and, hence, spectral similarity. To address this, a statistical method was previously developed in which two electron-ionization (EI) mass spectra are compared using the unequal variance t-test. Normalized intensities of corresponding ions are compared, testing the null hypothesis (H0 ) that the difference in intensity is equal to zero. If H0 is accepted at all m/z values, the two spectra are statistically equivalent at the specified confidence level. If H0 is not accepted at any m/z value, then there is a significant difference in intensity at that m/z value between the two spectra. In this work, the statistical comparison method is applied to distinguish EI spectra of valeryl fentanyl, isovaleryl fentanyl, and pivaloyl fentanyl. Spectra of the three analogs were collected over a 9-month period and at different concentrations. At the 99.9% confidence level, the spectra of corresponding isomers were statistically associated. Spectra of different isomers were statistically distinct, and ions responsible for discrimination were identified in each comparison. To account for inherent instrument variations, discriminating ions for each pairwise comparison were ranked based on the magnitude of the calculated t-statistic (tcalc ) value. For a given comparison, ions with higher tcalc values are those with the greatest difference in intensity between the two spectra and, therefore, are considered more reliable for discrimination. Using these methods, objective discrimination among the spectra was achieved and ions considered most reliable for discrimination of these isomers were identified.

Fluorescence of putative chromophores in Skh-1 and citrate-soluble calf skin collagens.

BACKGROUND/PURPOSE: Fluorescence of Skh-1 hairless mouse and calf skin acid-soluble type I collagens are envelopes of several bands putatively due to tyrosine (excitation/emission peak at 275/300 nm), dihydroxyphenylalanine (dopa; 280/325 nm), tyrosine aggregate (285/360 nm), dityrosine 325/400 nm), and advanced glycation end (AGE) product (370/450 nm), respectively. As these fluorophores can be markers of pathological conditions, we wish to present further evidence for or against these assignments. METHODS: We analysed intact type I mouse collagens and AGE by conventional fluorescence spectroscopy, synchronous spectroscopy, high-performance liquid chromatography (HPLC), and borate quenching. RESULTS: The relative amount of each fluorophore depends on the collagen sample. Acid- or enzyme-hydrolysis results in loss of fluorescence intensity at 350-400 nm, and enhanced emission 400-500 nm which could be reproduced by controlled dopa oxidation. Borate buffer quenches fluorescence at lambda>400 nm from intact collagens, dityrosine, dopa, and oxidized dopa but does not quench tyrosine or AGE fluorescence. CONCLUSION: Collagen fluorescence depends on its source and previous history. The data indicate that collagen fluorescence is derived from tyrosine, dopa, interacting tyrosine residues, covalent dityrosine, and dopa oxidation product(s), but not AGE.

Community-based trial of a triple-combination agent for the treatment of facial melasma.

Melasma is a common hyperpigmentation disorder that is frequently recalcitrant to treatment. An 8-week, multicenter, open-label, community-based study evaluated a new therapeutic approach that combines tretinoin 0.05%, hydroquinone 4.0%, and fluocinolone acetonide 0.01% (RA+HQ+FA) in a hydrophilic cream formulation. The trial enrolled 1290 patients of diverse races/ethnicities with a full range of Fitzpatrick skin types (I through VI). The mean Melasma Area and Severity Index (MASI) decreased significantly at both weeks 4 and 8 compared with baseline in the overall study population and across all Fitzpatrick skin types and races/ethnicities (P<.0001). The mean MASI darkness and homogeneity scores likewise fell significantly at weeks 4 and 8 in all facial regions involved (forehead, right and left malar regions, and chin) and in all Fitzpatrick skin types (P<.0001). By week 8, investigators' global evaluations showed that 75% of patients had "moderate or marked improvement" or were "almost clear" or "clear." The study medication was found to be safe and well tolerated. The results of this study demonstrate that RA+HQ+FA produces significant rapid improvement of melasma across the range of patients seen in daily practice, including whites, Hispanics, blacks, Asians, American Indians, Alaskan natives, and Pacific Islanders.

Modest in vivo exposure to solar wavelengths induces a visible absorbing chromophore in Skh-1 mouse epidermis.

BACKGROUND/PURPOSE: In the previous work, we correlated epidermal hyperplasia with increased epidermal absorption in the 250-400 nm region. During a recent review of that work, the apparent formation of a chromophore, with absorption slightly longer than 400 nm, in the epidermis of irradiated animals was noted. In this study, we have extended the transmission measurement to include the 250-800 nm region. METHODS: Age-matched Skh-1 hairless mice were separated into three groups. One group was irradiated with 6.3 J/cm(2) (0.9 minimal erythemal dose; MED) of solar simulating ultraviolet radiation (SSUVR) five times/week for 2 weeks, then increased to 1.1 MED (7.1 J/cm(2)) for two additional weeks (20-day group). A second 10-day group, added halfway through the protocol, was irradiated with 0.9 MED five times/week for 2 weeks. The control group received no UV irradiation. Routine H&E staining and epidermal absorption spectral analysis were carried out on biopsy specimens from each animal. RESULTS: This work confirms the development or enhancement of a visible chromophore with a maximum absorption at ca 412 nm. This peak appears to be radiation dose dependent. It can be discerned in both the groups, albeit more prominently in the 20-day animals. The absorption is sufficiently strong to impart a yellow to reddish appearance to skin viewed in full spectrum visible light. CONCLUSIONS: Accumulation of such a chromophore in humans may contribute to the coloration of chronically exposed skin. The absorption strength and wavelength location of the peak is strongly suggestive of a heme-like compound. We are currently conducting experiments to further characterize this chromophore.

Fluocinolone acetonide 0.01% in peanut oil: therapy for childhood atopic dermatitis, even in patients who are peanut sensitive.

BACKGROUND: Fluocinolone acetonide 0.01% in a blend of refined peanut and mineral oils has been used as treatment for scalp psoriasis for several years, but only more recently for atopic dermatitis. OBJECTIVE: We sought to study the effectiveness for atopic dermatitis, potential for adrenal axis suppression, and safety of the fluocinolone acetonide 0.01% in oil in children with atopic dermatitis, including children with atopic dermatitis and peanut allergic sensitivity. METHODS: Three separate studies were performed in children aged 2 to 12 years with atopic dermatitis: multicenter double-blind, randomized, and vehicle-controlled trial; cortisol stimulation testing; and prick testing, patch testing, and monitored medication use in children with peanut allergic sensitivity. RESULTS: Improvement of >/=50% was demonstrated within 2 weeks in 81% to 87% of 81 patients treated with active medication versus 39% of 45 children treated with vehicle oil alone. No adrenal suppression occurred after 4 weeks of therapy in 32 patients. None of 9 patients who were peanut sensitive reacted to either the full formulation or vehicle in prick or patch testing; 20 children who were peanut sensitive showed no allergic reactions after application of the medication. CONCLUSION: Fluocinolone 0.01% in peanut oil is an effective alternative to the use of topical corticosteroid agents in ointment, cream, and lotion forms in children. No evidence of adrenal suppression or adverse local effects were demonstrated in these studies. The medication was well tolerated in patients with peanut allergic sensitivity.