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Cochabamba, Costa Rica

Perrin C.,Central University of Costa Rica
American Journal of Dermatopathology

This second part of the review categorizes the site-specific nail tumors, as proposed in the first part, according to their clinical presentations. Acquired localized longitudinal pachyonychia allows for the specific recognition of onychogenic nail tumor, which can be classified into 2 groups according to the predominant compartment of origin within the nail unit as follows: epithelial tumors encompassing onychocytic matricoma and onychocytic carcinoma, and fibroepithelial tumors: the so-called onychomatricoma. As onychomatricoma is neither an epithelial matrical tumor nor a tumor with a limited differentiation toward the matrix, the author proposes instead the descriptive term of panonychoma fibropapilliferum (POP). The designation of POP does convey to the surgical pathologist or the dermatopathologist the key morphological pattern of this tumor. It should be noted that the proposed term of panonychoma is analogous to the nomenclature that is well established for follicular neoplasms with differentiation toward all elements of the normal hair follicle, that is panfolliculoma. The second term fibropapilliferum is used to highlight the mixed fibroepithelial nature of this neoplasm, which forms multiple rudimentary nail units. These nail units construct multiple nail plates that join together and form a single thick nail plate. According to nail anatomy, 2 types of POP are described: POP of the apical matrix/eponychium, with a pseudo-condylomatous pattern, and POP of the ventral matrix with a foliated pattern in transverse sections and a fibrokeratoma-like pattern in the longitudinal sections. Suggestions for the evaluation and clinical management of localized longitudinal pachyonychia are proposed. On histology of a nail clipping, 2 patterns with clinical significance can be individualized. A horizontal alignment of large cavities indicates POP of the ventral matrix. A haphazard arrangement of smaller cavities in the nail plate, including an arrangement in the inferior two-thirds of the nail clipping, should prompt a biopsy of the distal ventral matrix to rule out a malignant lesion. In the setting of the "masked "nail tumor, a clinical subtype with some significance can be individualized, the subungual keratotic nodule growing rapidly. Three nail bed tumors are discussed within this latter group. Two new clinicopathological variants of subungual keratoacanthoma are described, and a new nail bed tumor is discussed: the infundibulocystic nail bed squamous cell carcinoma. The absence of striking nuclear atypia and the giant cystic to multicystic pattern distinguishes infundibulocystic nail bed squamous cell carcinoma from follicular infundibulocystic squamous cell carcinoma. The last section proposes a classification of folliculogenic nail bed tumors. The follicular microcysts of the nail bed have previously been called subungual epidermoid inclusions or onycholemmal cysts, but the term follicular microcysts of the nail bed is more pertinent, because of the multiple lines of follicular differentiation (infundibular, tricholemmal, apocrine, and sebaceous) seen in their benign and malignant counterparts. Absent in a large portion of the normal nail bed, the follicular microcysts seem to have a peculiar propensity for the formation of tumors that vary in maturity from simple follicular microcystic hyperplasia associated with acquired longitudinal melanonychia to microcystic nail bed hamartoma and microcystic nail bed carcinoma (the so-called onycholemmal carcinoma). The concluding tables emphasize the key and essential histological features required to make the diagnosis of site-specific nail tumors and guide appropriate therapy. The author proposes to categorize subungual tumors into 2 types: subungual skin tumors (including subungual skin metastasis from internal malignancies) and nail tumors. Nail tumors can be accurately classified using a combined clinical and histogenetic approach. This new and expanding group of appendageal tumors is important for both dermatologists and dermatopathologists for the potential early detection of a malignant lesion or for the avoidance of overtreatment of a benign lesion. © 2013 Lippincott Williams & Wilkins. Source

Zhai L.,Central University of Costa Rica
Chemical Society Reviews

Stimuli-responsive polymer films undergo interesting structural and property changes upon external stimuli. Their applications have extended from smart coatings to controlled drug release, smart windows, self-repair and other fields. This tutorial review summarizes non-covalent bonding, reversible reactions and responsive molecules that have played important roles in creating stimuli-responsive systems, and presents the recent development of three types of responsive polymer systems: layer-by-layer polymer multilayer films, polymer brushes, and self-repairing polymer films, with a discussion of their response mechanism. Future research efforts include comprehensive understanding of the response mechanism, producing polymer systems with controlled response properties regarding single or multiple external signals, combining polymer film fabrication with nanotechnology, improving the stability of polymer films on substrates, and evaluating the toxicity of the degradation products. © 2013 The Royal Society of Chemistry. Source

Central University of Costa Rica | Date: 2011-07-14

A solid state energy conversion device and method of making is disclosed for converting energy between electromagnetic and electrical energy. The solid state energy conversion device comprises a wide bandgap semiconductor material having a first doped region. A thermal energy beam is directed onto the first doped region of the wide bandgap semiconductor material in the presence of a doping gas for converting a portion of the first doped region into a second doped region in the wide bandgap semiconductor material. A first and a second Ohmic contact are applied to the first and the second doped regions of the wide bandgap semiconductor material. In one embodiment, the solid state energy conversion device operates as a light emitting device to produce electromagnetic radiation upon the application of electrical power to the first and second Ohmic contacts. In another embodiment, the solid state energy conversion device operates as a photovoltaic device to produce electrical power between the first and second Ohmic contacts upon the application of electromagnetic radiation.

Central University of Costa Rica | Date: 2011-06-22

In one aspect, the invention relates to substituted purine analogs, derivatives thereof, and related compounds, which are useful as inhibitors of STAT protein activity; synthetic methods for making the compounds; pharmaceutical compositions comprising the compounds; and methods of treating disorders of uncontrolled cellular proliferation associated with a STAT protein activity dysfunction using the compounds and compositions. This abstract is intended as a scanning tool for purposes of searching in the particular art and is not intended to be limiting of the present invention.

Babu N.J.,University of Nottingham | Nangia A.,Central University of Costa Rica
Crystal Growth and Design

The current phase of drug development is witnessing an oncoming crisis due to the combined effects of increasing R&D costs, decreasing number of new drug molecules being launched, several blockbuster drugs falling off the patent cliff, and a high proportion of advanced drug candidates exhibiting poor aqueous solubility. The traditional approach of salt formulation to improve drug solubility is unsuccessful with molecules that lack ionizable functional groups, have sensitive moieties that are prone to decomposition/racemization, and/or are not sufficiently acidic/basic to enable salt formation. Several novel examples of pharmaceutical cocrystals from the past decade are reviewed, and the enhanced solubility profiles of cocrystals are analyzed. The peak dissolution for pharmaceutical cocrystals occurs in a short time (<30 min), and high solubility is maintained over a sufficiently long period (4-6 h) for the best cases. The enhanced solubility of drug cocrystals is similar to the supersaturation phenomenon characteristic of amorphous drugs. However, in contrast to the metastable nature of amorphous phases, cocrystals are stable owing to their crystalline nature. Yet, cocrystals can exhibit dramatic solubility advantage over the stable crystalline drug form, often comparable to amorphous pharmaceuticals. The "spring and parachute" concept for amorphous drug dissolution is adapted to explain the solubility advantage of pharmaceutical cocrystals. Thus (1) the cocrystal dissociates to amorphous or nanocrystalline drug clusters (the spring), which (2) transform via fast dissolving metastable polymorphs to the insoluble crystalline modification following the Ostwalds Law of Stages, to give (3) high apparent solubility for cocrystals and optimal drug concentration (the parachute) in the aqueous medium. © 2011 American Chemical Society. Source

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