The relationship of telomere length to baseline corticosterone levels in nestlings of an altricial passerine bird in natural populations

Artículo de publicación ISIBackground: Environmental stressors increase the secretion of glucocorticoids that in turn can shorten telomeres via oxidative damage. Modification of telomere length, as a result of adversity faced early in life, can modify an individual's phenotype. Studies in captivity have suggested a relationship between glucocorticoids and telomere length in developing individuals, however less is known about that relationship in natural populations. Methods: In order to evaluate the effect of early environmental stressors on telomere length in natural populations, we compared baseline corticosterone (CORT) levels and telomere length in nestlings of the same age. We collected blood samples for hormone assay and telomere determination from two geographically distinct populations of the Thorn-tailed Rayadito (Aphrastura spinicauda) that differed in brood size; nestlings body mass and primary productivity. Within each population we used path analysis to evaluate the relationship between brood size, body mass, baseline CORT and telomere length. Results: Within each distinct population, path coefficients showed a positive relationship between brood size and baseline CORT and a strong and negative correlation between baseline CORT and telomere length. In general, nestlings that presented higher baseline CORT levels tended to present shorter telomeres. When comparing populations it was the low latitude population that presented higher levels of baseline CORT and shorter telomere length. Conclusions: Taken together our results reveal the importance of the condition experienced early in life in affecting telomere length, and the relevance of integrative studies carried out in natural conditions.FONDECYT Grant 11130245 FONDECYT 1140548 USA National Science Foundation Grant IOS-0750540 ICM-005-002 PFB-23-CONICY

Use of Panitumumab-IRDye800 to Image Microscopic Head and Neck Cancer in an Orthotopic Surgical Model

BACKGROUND: Fluorescence imaging hardware (SPY) has recently been developed for intraoperative assessment of blood flow via detection of probes emitting in the near-infrared (NIR) spectrum. This study sought to determine if this imaging system was capable of detecting micrometastatic head and neck squamous cell carcinoma (HNSCC) in preclinical models. METHODS: A NIR fluorescent probe (IRDye800CW) was covalently linked to a monoclonal antibody targeting EGFR (panitumumab) or non-specific IgG. HNSCC flank (SCC-1) and orthotopic (FADU and OSC19) xenografts were imaged 48-96hrs following systemic injection of labeled panitumumab or IgG. The primary tumor and regional lymph nodes were dissected using fluorescence guidance with the SPY system and grossly assessed with a charge-coupled NIR system (Pearl). Histologic slides were also imaged with a NIR charged-coupled device (Odyssey) and fluorescence intensity was correlated with pathologic confirmation of disease. RESULTS: Orthotopic tongue tumors were clearly delineated from normal tissue with tumor-to-background ratios of 2.9(Pearl) and 2.3(SPY). Disease detection was significantly improved with panitumumab-IRDye compared to IgG-IRDye800 (P<0.05). Tissue biopsies (average size=3.7mm) positive for fluorescence were confirmed for pathologic disease by histology and immunohistochemistry (n=25/25). Biopsies of non-fluorescent tissue were proven to be negative for malignancy (n=28/28). The SPY was able to detect regional lymph node metastasis (<1.0mm) and microscopic areas of disease. Standard histological assessment in both frozen and paraffin-embedded histologic specimens was augmented using the Odyssey. CONCLUSIONS: Panitumumab-IRDye800 may have clinical utility in detection and removal of microscopic HNSCC using existing intraoperative optical imaging hardware and may augment analysis of frozen and permanent pathology

Intraoperative Consultation (IOC) in Mucosal Lesions of the Upper Aerodigestive Tract

Intraoperative consultation (frozen section) plays an important part in the treatment of the head and neck cancer patient. The appropriate use of intraoperative consultations (frozen sections) usually results in a definitive diagnosis with immediate therapeutic impact while the patient is in the operating room. Among the determinations made by frozen section analysis include the evaluation of adequacy of surgical margins of resection; the differentiation between nonneoplastic, benign and malignant proliferations; the evaluation of lymph nodes for the presence of metastatic disease; the determination of specimen identification and specimen adequacy, including the verification of such organs as the parathyroid glands; and the determination of whether a given case requires special diagnostic testing best performed on frozen material, such as for lymphomas. This paper focuses on intraoperative consultation of mucosal lesions of the upper aerodigestive tract, including epithelial dysplasia and squamous cell carcinoma. Other issues that often not diagnosed or at issue at the time of surgery, including the diagnosis of microinvasive carcinoma and differentiating inflammatory lesions from neoplastic lesions are included for completion

Morphological and behavioural adaptations to feed on nectar: how feeding ecology determines the diversity and composition of hummingbird assemblages

Hummingbirds are the most specialised nectarivorous birds and show close ecological relationships to their food plants. Their small body size, bright colors, and unique behaviour have fascinated generations of naturalists. In this review, we investigate the morphological and behavioural adaptations of hummingbirds to feed on nectar and arthropods, and explore their diffuse co-evolution with their food plant species. Further, a list of plant genera including species mainly pollinated by hummingbirds is presented. Summarising the existing knowledge on hummingbird feeding ecology, we find that much of the variability in morphology and behaviour of hummingbirds is determined by their unique feeding mode and the constraints set by their food plants. Based on the existing literature, we developed a hierarchical system explaining how different environmental factors have shaped the current richness of hummingbirds, and their morphological and behavioural diversity. We propose that climatic stability within and between seasons and days determines the constancy of food availability, which in turn is the most important factor for species richness in hummingbird assemblages. However, the assemblage composition of hummingbirds is also influenced by phylogenetic factors, especially under harsh environmental conditions. Unsurprisingly, the highest morphological and behavioural diversity is observed in the most species-rich assemblages. This diversity may have at least partly evolved to reduce inter- and intraspecific competition. Independently of which morphological character we consider, the 360 different hummingbird species have evolved a large morphological variability to adapt to their individual feeding niches