Low-temperature adsorption of H2S on Ag(111)

H2S forms a rich variety of structures on Ag(111) at low temperature and submonolayer coverage. The molecules decorate step edges, exist as isolated entities on terraces, and aggregate into clusters and islands, under various conditions. One type of island exhibits a (×)R25.3° unit cell. Typically, molecules in the clusters and islands are separated by about 0.4 nm, the same as the S–S separation in crystalline H2S. Density functional theory indicates that hydrogen-bonded clusters contain two types of molecules. One is very similar to an isolated adsorbed H2S molecule, with both S–H bonds nearly parallel to the surface. The other has a S–H bond pointed toward the surface. The potential energy surface for adsorption and diffusion is very smooth

A fast and cost-effective approach to develop and map EST-SSR markers: oak as a case study

Background: Expressed Sequence Tags (ESTs) are a source of simple sequence repeats (SSRs) that can be used to develop molecular markers for genetic studies. The availability of ESTs for Quercus robur and Quercus petraea provided a unique opportunity to develop microsatellite markers to accelerate research aimed at studying adaptation of these long-lived species to their environment. As a first step toward the construction of a SSR-based linkage map of oak for quantitative trait locus (QTL) mapping, we describe the mining and survey of EST-SSRs as well as a fast and cost-effective approach (bin mapping) to assign these markers to an approximate map position. We also compared the level of polymorphism between genomic and EST-derived SSRs and address the transferability of EST-SSRs in Castanea sativa (chestnut). Results: A catalogue of 103,000 Sanger ESTs was assembled into 28,024 unigenes from which 18.6% presented one or more SSR motifs. More than 42% of these SSRs corresponded to trinucleotides. Primer pairs were designed for 748 putative unigenes. Overall 37.7% (283) were found to amplify a single polymorphic locus in a reference fullsib pedigree of Quercus robur. The usefulness of these loci for establishing a genetic map was assessed using a bin mapping approach. Bin maps were constructed for the male and female parental tree for which framework linkage maps based on AFLP markers were available. The bin set consisting of 14 highly informative offspring selected based on the number and position of crossover sites. The female and male maps comprised 44 and 37 bins, with an average bin length of 16.5 cM and 20.99 cM, respectively. A total of 256 EST-SSRs were assigned to bins and their map position was further validated by linkage mapping. EST-SSRs were found to be less polymorphic than genomic SSRs, but their transferability rate to chestnut, a phylogenetically related species to oak, was higher. Conclusion: We have generated a bin map for oak comprising 256 EST-SSRs. This resource constitutes a first step toward the establishment of a gene-based map for this genus that will facilitate the dissection of QTLs affecting complex traits of ecological importance

Cáncer de piel: melanoma. Revisión de la literatura

Skin cancer is usually classified into melanoma (SCM) and non-melanoma (SCNM), with different cell origins; being the SCM responsible for the highest mortality. In Chile, an incidence (2008) of 434 new cases is estimated, obtaining a standardized rate of 2.2 cases per 100,000 habitants. There are multiple associated risk factors, the main ones being exposure to UV radiation and sunburn. The strategies to prevent this pathology fall on these same factors. The clinical evaluation of the lesions with ABCD mnemonics added to the use of dermoscopy increases the diagnostic sensitivity and specificity; however, the definitive confirmation is through biopsy, which must include the necessary parameters to define prognosis of disease. The definitive treatment is Surgical. There are alternatives such as the use of the sentinel lymph node to define lymph node dissections. Regarding systemic therapies, the use of immunotherapy has shown results that improve survival in these patients

Tumores de glándulas salivales: enfrentamiento diagnóstico inicial

It is described that salivary gland tumors account for up to 3-6% of head and neck tumors, 80% of these being located in the parotid gland. Broadly speaking, the smaller the gland, the greater the probability of malignancy. The most common clinical manifestation in tumor pathology is the appearance of a painless mass. Indicators of malignancy should be considered: chronic volume increase or rapid growth, facial paralysis, cranial nerve involvement, ulceration, and cervical lymphadenopathy. Ultrasonography should be the first imaging study, however, it provides limited information. MRI is the exam of choice for salivary gland tumors, whereas CT and PET-CT allow the study of local and remote invasion. FNA is controversial, it is not indicated for all patients, in parotid tumors a cytological examination is usually not necessary prior to surgery. Excisional biopsy is not recommended due to the risk of tumor seeding, neural damage, and salivary fistula. The goal of treatment in gland tumors is the removal of the glands, associated with lymph node dissection and adjuvant radiation therapy in indicated cases. The general practitioner must comprehensively address these pathologies to achieve a timely referral to the specialist

Infecciones profundas del cuello

Deep neck infections (DNIs) are special entities among infectious diseases for their versatility and potential for severe complications. Complex head and neck anatomy often makes early recognition of DNIs challenging, and a high index of suspicion is necessary to avoid any delay in treatment. The diagnosis is made by clinical history, physical examination findings and imaging studies. The treatment consists in securing the airway, intravenous antibiotics and surgical drainage, when needed. To make decisions the surgeon must understand the anatomy of the region, the etiology of infection, appropriate diagnostic tools, and medical and surgical management. This article provides a review of these pertinent topics

Structural plasticity in hippocampal cells related to the facilitative effect of intracranial self-stimulation on a spatial memory task

Posttraining intracranial self-stimulation (SS) in the lateral hypothalamus facilitates the acquisition and retention of several implicit and explicit memory tasks. Here, intracellular injections of Lucifer yellow were used to assess morphological changes in hippocampal neurons that might be specifically related to the facilitative posttraining SS effect upon the acquisition and retention of a distributed spatial task in the Morris water maze. We examined the structure, size and branching complexity of cornus ammonis 1 (CA1) cells, and the spine density of CA1 pyramidal neurons and granular cells of the dentate gyrus (DG). Animals that received SS after each acquisition session performed faster and better than Sham ones-an improvement that was also evident in a probe trial 3 days after the last training session. The neuromorphological analysis revealed an increment in the size and branching complexity in apical CA1 dendritic arborization in SS-treated subjects as compared with Sham animals. Furthermore, increased spine density was observed in the CA1 field in SS animals, whereas no effects were observed in DG cells. Our results support the hypothesis that the facilitating effect of SS on the acquisition and retention of a spatial memory task could be related to structural plasticity in CA1 hippocampal cells.Peer Reviewe