A Structure-Based Discovery Platform for BACE2 and the Development of Selective BACE Inhibitors.

The ability to perform routine structure-guided drug design for selective BACE inhibitors has been limited because of the lack of robust platform for BACE2 expression, purification, and crystallization. To overcome this limitation, we developed a platform that produces 2-3 mg of pure BACE2 protein per liter of culture, and we used this protein to design macrocyclic compounds that potently and selectively inhibit BACE1 over BACE2. Compound was found to potently inhibit BACE 1 ( = 5 nM) with a selectivity of 214-fold over BACE2.

Development of an Efficient Enzyme Production and Structure-Based Discovery Platform for BACE1 Inhibitors.

BACE1 (Beta-site Amyloid Precursor Protein (APP) Cleaving Enzyme 1) is a promising therapeutic target for Alzheimer's Disease (AD). However, efficient expression, purification, and crystallization systems are not well described or detailed in the literature nor are approaches for treatment of enzyme kinetic data for potent inhibitors well described. We therefore developed a platform for expression and purification of BACE1, including protein refolding from inclusion bodies, in addition to optimizing a reproducible crystallization procedure of BACE1 bound with inhibitors.

Mechanism of action of 4-substituted phenols to induce vitiligo and antimelanoma immunity.

Monobenzone is a 4-substituted phenol that can induce vitiligo and antimelanoma immunity. We investigated the influence of the chemical structure on the biological activity of a series of structurally related 4-substituted phenols. All phenols inhibited cellular melanin synthesis, and eight of ten phenols inhibited tyrosinase activity, using the MBTH assay.

Oxidation events and skin aging.

The rate of skin aging, or that of tissue in general, is determined by a variable predominance of tissue degeneration over tissue regeneration. This review discusses the role of oxidative events of tissue degeneration and aging in general, and for the skin in particular. The mechanisms involved in intrinsic and extrinsic (photo-) aging are described.

Anti-inflammatory effects of urocanic Acid derivatives in models ex vivo and in vivo of inflammatory bowel disease.

Urocanic acid (UCA) derivatives were tested for their anti-inflammatory activity in inflammatory bowel disease (IBD) in two models: ex vivo and an experimental mouse model. Ex vivo: inflamed colonic tissue was incubated in culture medium with or without the UCA derivatives. Biopsies, incubated with UCA derivatives, produced lower levels of proinflammatory cytokines IL-6 and IL-8 as compared to control biopsies.

Increased sensitivity of histidinemic mice to UVB radiation suggests a crucial role of endogenous urocanic acid in photoprotection.

Urocanic acid (UCA) is produced by the enzyme histidase and accumulates in the stratum corneum of the epidermis. In this study, we investigated the photoprotective role of endogenous UCA in the murine skin using histidinemic mice, in which the gene encoding histidase is mutated. Histidase was detected by immunohistochemistry in the stratum granulosum and stratum corneum of the normal murine skin but not in the histidinemic skin.

Natural moisturizing factor components in the stratum corneum as biomarkers of filaggrin genotype: evaluation of minimally invasive methods.

Background: The carriers of loss-of-function mutations in the filaggrin gene (FLG) have reduced levels of natural moisturizing factor (NMF) in the stratum corneum. The concentration of NMF components which are formed by filaggrin protein breakdown in the stratum corneum might therefore be useful as a biomarker of the FLG genotype. OBJECTIVES To investigate the feasibility of different sampling methods for the determination of two NMF components, 2-pyrrolidone-5-carboxylic acid (PCA) and urocanic acid (UCA), in the stratum corneum as biomarkers for the FLG genotype.

Postelicitation model of allergic contact dermatitis for predicting the efficacy of topical drugs.

To evaluate the anti-inflammatory efficacies of topical drugs, models of contact hypersensitivity (CHS) can be used, but the conventional murine models of CHS need revision in this respect. These models utilize sensitized mice to study suppression of sensitization or elicitation by test compounds. To mimick the events occurring in allergic contact dermatitis (ACD), a modification of the murine model of CHS is needed in a way that a chronic postelicitation phase of CHS is maintained for studies of anti-inflammatory effects of topical drugs, typically relevant for ACD therapy, not for ACD prevention.

Suppression of different phases of systemic contact hypersensitivity by urocanic acid oxidation products.

On exposure to UV-B, the epidermal component trans-urocanic acid (UCA) is not only photoisomerized into cis-UCA but will also, at least in part, be photooxidized into UCA oxidation products (UOPs). We hypothesized that UOPs can mimic UV-induced systemic immunosuppression comparable to the suppressive properties already established for cis-UCA. A crude mixture of UOPs showed a significant suppression of the sensitization phase of the systemic contact hypersensitivity (CHS) response to picryl chloride (PCl).

[European standard regarding clothing and protection against ultraviolet radiation].

Overexposure to ultraviolet radiation (UVR) causes skin damage. An increasing awareness of this must result in people consciously wanting to protect themselves from UVR by means of clothing. The first part of the European standard on UVR-protective clothing--about test methods--is now available.

The effect of mechanical cleaning and thermal disinfection on light intensity provided by fibrelight Macintosh laryngoscopes.

The increased use of thermal decontamination procedures for fibrelight laryngoscope blades, to comply with international guidelines, will have considerable economical effects. We evaluated the effect of mechanical cleaning plus thermal disinfection at 90 degrees C, with or without subsequent steam sterilisation at 134 degrees C, on light intensity provided by fibrelight laryngoscopes. After mounting the blades in a special frame with a built-in light source, light intensity was measured using radiometer/photometer.

Epidermal cis-urocanic acid levels correlate with lower specific cellular immune responses after hepatitis B vaccination of ultraviolet B-exposed humans.

Urocanic acid (UCA) is a major UV-absorbing chromophore in the epidermis and has been suggested to act as one of the initiators of UV-induced immunosuppression. cis-UCA, the isomer from UCA that is formed upon UV exposure, has been shown to impair some cellular immune responses. cis-UCA levels were determined in a study in which the influence of ultraviolet B (UVB) exposure on immune responses after hepatitis B vaccination in human volunteers was established.

Oxidative breakdown and conversion of urocanic acid isomers by hydroxyl radical generating systems.

cis-Urocanic acid (cis-UCA), formed from trans-urocanic acid (trans-UCA) by photoisomerization, has been shown to mimic suppressive effects of UV on the immune system. It is our hypothesis that UCA oxidation products in the skin play a role in the process of immunosuppression. Recently, both UCA isomers were found to be good hydroxyl radical scavengers and in this context we investigated the formation of products resulting from the interaction of hydroxyl radicals with UCA.

Urocanic acid isomers are good hydroxyl radical scavengers: a comparative study with structural analogues and with uric acid.

UV-exposure of the epidermis leads to the isomerisation of trans-UCA into cis-UCA as well as to the generation of hydroxyl radicals. This study shows by means of the deoxyribose degradation test that UCA isomers are more powerful hydroxyl radical scavengers than the other 4-(5-)substituted imidazole derivatives, such as histidine, though less powerful than uric acid. UCA, present in relatively high concentrations in the epidermis, may well be a major natural hydroxyl radical scavenger.

In vitro tissue-digesting properties of krill enzymes compared with fibrinolysin/DNAse, papain and placebo.

Wound debridement, the removal of necrotic tissue, can be achieved with proteolytic enzymes. Recently, a new multi-enzyme preparation, krill enzyme, isolated from Antarctic shrimp-like organisms (Euphausia superba), was reported to possess powerful proteolytic activity towards protein substrates. In this paper, we study the in vitro digestive properties of krill enzymes towards whole tissue, compared with placebo, papain, and fibrinolysin/DNAse.

Prolonged increase of cis-urocanic acid levels in human skin and urine after single total-body ultraviolet exposures.

Cis-urocanic acid (cis-UCA), a mediator of immunosuppression, is formed from trans-UCA upon UV-exposure of the skin. This study describes a liquid chromatographic method for the simultaneous quantification of cis- and trans-UCA in skin, urine and plasma of nonirradiated volunteers. It also describes cis- and trans-UCA kinetics in UV-irradiated volunteers.

Determinants of dual chamber pulse generators longevity.

The aim of this study was to investigate the effect of battery capacity, internal current drain, and stimulation energy on pulse generators longevity, and if battery impedance measurements can reliably predict pulse generators end-of-life. For this purpose, the records of 577 patients with a mean age of 65 +/- 14 years who had undergone implantation of two different dual chamber pulse generators (PG1: 409; PG2: 168) were retrospectively reviewed. Battery capacity were 2.

Photoisomerization spectrum of urocanic acid in human skin and in vitro: effects of simulated solar and artificial ultraviolet radiation.

Ultraviolet (UV) irradiation of trans-urocanic acid (UCA), a major UV absorbing component of the epidermis, leads to the formation of cis-UCA, which mediates immunosuppressive effects. In this study, the net yield of cis-UCA was measured after the photoisomerization of urocanic acid by narrow UV wavebands (spectral range 295-405 nm), with the irradiation doses related to solar irradiance at sea level. The formation of cis-UCA in Caucasian skin (in vivo), as well as in aqueous solution (in vitro), was determined by HPLC analysis.

Preparation of monoclonal mouse antibodies against two specific eu-melanin related compounds.

Two eu-melanin precursors, 6-hydroxy-5-methoxyindole-2-carboxylic acid (HMI2C) and 5,6-dihydroxyindole-2-carboxylic acid (DHI2C) were synthesized and coupled to bovine serum albumin, hemocyanin and polylysine by the combined action of carbodiimide and succinimide. These indole-carrier conjugates served as antigens for the production of specific antibodies against DHI2C and HMI2C in BALB/c mice. The specificity of these antibodies was tested using a combination of affinity chromatography and ELISA procedures.

Determination of catechol O-methyltransferase activity in relation to melanin metabolism using high-performance liquid chromatography with fluorimetric detection.

A new sensitive method for the determination of catechol O-methyltransferase activity has been developed. The method is based on the O-methylation of the indolic intermediates of melanin metabolism. The substrate, 5,6-dihydroxyindole-2-carboxylic acid, is converted by the enzyme to two O-methylated products, which can be separated by high-performance liquid chromatography and measured with fluorimetric detection.

The relation between constitutional skin color and photosensitivity estimated from UV-induced erythema and pigmentation dose-response curves.

In 54 healthy volunteers we assessed predictors of sensitivity to ultraviolet (UV) light, including Fitzpatrick's sun reactive skin types and constitutional skin color, and compared these with one another and with responses of the skin to UV irradiation, as determined experimentally by a minimal erythema dose (MED), a minimal melanogenic dose (MMD), and dose-response curves for UV-induced erythema and pigmentation. For these studies, a xenon arc solar simulator was used as the source of UV irradiation, and a chromameter interfaced with a computer for objective measurement of UV-induced erythema and pigmentation was employed. The skin type did not correspond well to the constitutional skin color, as measured by a chromameter prior to UV irradiation.

Inhibition of cellular infiltration at the site of Arthus reaction by chlorpromazine. Use of a new area integration technique.

Chlorpromazine, an inhibitor of the complement (C) system, inhibited the cellular infiltration at the site of Arthus reaction (AR), as assessed by a newly developed computerized area integration technique (CAIT). This inhibition was rather strong (mean value 92%) and statistically significant according to the classical quotient estimator. This may, at least in part, explain the protection of vessel wall destruction by chlorpromazine in AR, as observed in a previous study.