ABCG2/BCRP transport mechanism revealed through kinetically excited targeted molecular dynamics simulations.

ABCG2/BCRP is an ABC transporter that plays an important role in tissue protection by exporting endogenous substrates and xenobiotics. ABCG2 is of major interest due to its involvement in multidrug resistance (MDR), and understanding its complex efflux mechanism is essential to preventing MDR and drug-drug interactions (DDI). ABCG2 export is characterized by two major conformational transitions between inward- and outward-facing states, the structures of which have been resolved. Yet, the entire transport cycle has not been characterized to date. Our study bridges the gap between the two extreme conformations by studying connecting pathways. We developed an innovative approach to enhance molecular dynamics simulations, 'kinetically excited targeted molecular dynamics', and successfully simulated the transitions between inward- and outward-facing states in both directions and the transport of the endogenous substrate estrone 3-sulfate. We discovered an additional pocket between the two substrate-binding cavities and found that the presence of the substrate in the first cavity is essential to couple the movements between the nucleotide-binding and transmembrane domains. Our study shed new light on the complex efflux mechanism, and we provided transition pathways that can help to identify novel substrates and inhibitors of ABCG2 and probe new drug candidates for MDR and DDI.

SERUM ZONULIN LEVELS IN HYPOTHYROID AND EUTHYROID PATIENTS WITH HASHIMOTO'S THYROIDITIS - A PILOT STUDY.

Context: Human zonulin is a protein that regulates the intercellular tight junctions in various tissues and organs of the human body. Hashimoto's thyroiditis (HT) is one of the most common endocrine autoimmune disorder, but the role of increased intestinal permeability in its pathogenesis is still being studied. Objective and design: This pilot cross-sectional study investigates serum zonulin concentration in adults with Hashimoto's thyroiditis and assesses the relationship between zonulin levels, clinical hormonal and immunological characteristics. Subjects and methods: A group of 62 adults with HT participated in this study and were divided into three groups: hypothyroid (n=33) euthyroid (n=25) and hyperthyroid (n=4). Serum zonulin was determined using an ELISA method. Results: Age, gender and BMI were different between groups (hypothyroid and euthyroid ones). Serum zonulin values ranged from 2.6 to 198.0 ng/mL in participants. A direct positive correlation was found between serum zonulin levels and weight and BMI (r = 0.351, p = 0.008 and r = 0.236, p = 0.05, respectively). Conclusions: There is no correlation between zonulin and thyroid hormones or autoantibodies in Hashimoto thyroiditis patients. There is a difference in zonulin levels between the studied groups, but they are not statistically significant.

Ex vivo dermatoscopy of scalp specimens and slides.

BACKGROUND: Correct evaluation of horizontal scalp biopsies requires accurate gross sectioning and embedding of the tissue. The most common issue during processing includes incorrect specimen bisection. OBJECTIVES: To verify if (i) ex vivo assessment of scalp biopsies by contact dermatoscopy can identify the correct plane of transverse bisection as well as (ii) if using contact dermatoscopy on the glass slides can be useful to control the tissue processing and expedite sign-out. MATERIALS AND METHODS: For the first aim, dermatoscopic pictures of 43 scalp biopsies were printed and shown to 10 dermatology residents not involved in the study, who were asked to identify and highlight the dermo-epidermal junction. For the second aim, dermatoscopic captions of 40 horizontal sections were evaluated in a blinded way for the size of the specimen as well as the level and plane of bisection. The agreement was investigated using Cohen's κ statistics. RESULTS: Ten independent observers were able to correctly identify the dermo-epidermal junction as a brownish wavy line in 95.3% cases. The Cohen's κ statistics showed almost perfect agreement. Two independent pathologists agreed on the specimen size in all cases, on the specimen plane in 39 cases and on the specimen level on 35 cases. The Cohen's κ statistics showed almost complete agreement for the size and plane of bisection and substantial agreement for the level of section. CONCLUSION: Ex vivo dermatoscopy of scalp biopsies may be a new way to decrease laboratory costs and improve turnaround time in hair pathology as this technique optimally guides the correct bisection at 1-1.5 mm below the junction. Ex vivo dermatoscopy on the slides may expedite sign out after the initial bisection.

Onychomatricoma has channel-like structures on in vivo reflectance confocal microscopy.

BACKGROUND: Onychomatricoma is a benign fibroepithelial nail matrix tumor that infiltrates the nail plate leading to multiple tunneled cavities lined with matrix epithelium and filled with serum. Diagnostic features of onychomatricoma on reflectance confocal microscopy (RCM) have not been previously described. OBJECTIVE: We sought to demonstrate the feasibility of using RCM to diagnose onychomatricoma. METHODS: Reflectance confocal microscopy was used to evaluate four patients with onychomatricoma before tumor excision. We evaluated the affected nail and one unaffected nail of each patient with VivaScope 1500 (Lucid Inc., Rochester, NY, USA). RESULTS: Reflectance confocal microscopy evaluation of onychomatricomas revealed longitudinal dark areas and bright/grey lines, forming channel like structures. The channels were outlined by bright circular lines with grey dot centers. These RCM features correlated with the pathology of the onychomatricomas within the nail plate. LIMITATIONS: Proximal portion of onychomatricoma was not reach by RCM. CONCLUSIONS: Reflectance confocal microscopy can assist in rapid and noninvasive diagnosis of onychomatricoma showing characteristic channel like structures within nail plates.

1,2,4-Oxadiazoles identified by virtual screening and their non-covalent inhibition of the human 20S proteasome.

Although several constitutive proteasome inhibitors have been reported these recent years, potent organic, noncovalent and readily available inhibitors are still poorly documented. Here we used a structure- and ligand-based in silico approach to identify commercially available 1,2,4-oxadiazole derivatives as non-covalent human 20S proteasome inhibitors. Their optimization led to the newly synthesized compound 4h that is a mixed proteasomal inhibitor of the chymotrypsin- like activity (K(i) of 26,1 nM and K'(i) of 7.5 nM) which is in addition selective versus the challenging cathepsin B and calpain proteases. Molecular modelling studies corroborated the mechanism of inhibition and suggest an unusual binding of the inhibitor within the S5 binding pocket (ß6 subunit). The cellular effects of our compounds validate their utility as potential pharmacological agents for anti-cancer pre-clinical studies.

La dermatoscopia de la celulitis disecante precoz del cuero cabelludo es similar a de la alopecia areata / Dermoscopy of Early Dissecting Cellulitis of the Scalp Simulates Alopecia Areata

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Dermoscopy guided scalp biopsy in cicatricial alopecia.

BACKGROUND: Scalp biopsies are crucial for the diagnosis of cicatricial alopecia. However, the pathologic interpretation may not be diagnostic if biopsy is not obtained from the correct site. This is particularly relevant for cicatricial alopecia as the disease may be focal and disease activity difficult to appreciate by the naked eye. OBJECTIVE: To report a new simple technique to select the optimal biopsy site in cicatricial alopecia. METHODS: In the last 2 years we performed dermoscopy guided scalp biopsies using handled dermatoscopes in 80 patients with different forms of cicatricial alopecia. Biopsy site was selected based on presence of the following dermatoscopic features: perifollicular concentric white scales in lichen planopilaris, frontal fibrosing alopecia (FFA) and discoid lupus erythematosus (DLE); hair tufts in folliculitis decalvans, hairs surrounded by a peripilar grey-white halo in central centrifugal cicatricial alopecia and follicular red dots or keratotic plugs in DLE. RESULTS: The dermoscopy guided biopsies yielded a definitive pathological diagnosis in 95% of the cases. COMMENT: The advantage of this method is that it is a fast, precise way to identify even individually affected follicles in early or focal cicatricial alopecia. It also allows for the morphologic characterization of particular follicular structures.

'A detective look' at hair biopsies from African-American patients.

BACKGROUND: A patient's ethnicity can be an important clue in the diagnosis of scarring alopecia as some disorders such as traction alopecia (TA) and central centrifugal cicatricial alopecia (CCCA) are more prevalent in or exclusive to African-Americans. OBJECTIVES: To perform a retrospective review of 60 scalp biopsies from African-American patients including 25 cases of CCCA, 22 cases of TA, five cases of frontal fibrosing alopecia, three cases of discoid lupus erythematosus, three cases of hair breakage and two cases of alopecia areata. METHODS: Serial horizontal and vertical sections were examined. RESULTS: Features characteristic of the African-American scalp include: golf club-shaped bulb, elliptical shape of the hair shaft, asymmetrical outer root sheath and paired grouping of hair follicles. Clues to the diagnosis of CCCA include: premature desquamation of the inner root sheath, goggles and naked hair shafts in fibrous streamers. Diagnosis of TA is suggested by preserved sebaceous glands along with follicular miniaturization and drop-out. CONCLUSIONS: The clues reported here aim to help the dermatopathologists to: recognize at a glance that they are dealing with a scalp biopsy from an African-American patient; make the most probable diagnosis by connecting the clues (even if only vertical sections are present); and understand the morphological basis for the susceptibility of the African hair to damage.

AMMOS software: method and application.

Recent advances in computational sciences enabled extensive use of in silico methods in projects at the interface between chemistry and biology. Among them virtual ligand screening, a modern set of approaches, facilitates hit identification and lead optimization in drug discovery programs. Most of these approaches require the preparation of the libraries containing small organic molecules to be screened or a refinement of the virtual screening results. Here we present an overview of the open source AMMOS software, which is a platform performing an automatic procedure that allows for a structural generation and optimization of drug-like molecules in compound collections, as well as a structural refinement of protein-ligand complexes to assist in silico screening exercises.