Vasculogenesis in the chick embryo optic tectum

The initial formation and further development of the intraneural blood vessel network in the tectum opticum of the chick from the 4th to the 14th incubation day have been analyzed and some quantitative data morphometrically recorded. Vessels have been filled by intracardial injection of India ink in vivo. As inferred from our previous investigations on the vasculogenesis of several districts of the central and peripheral nervous system in the chick embryo, also in the developing optic tectum growth and distribution pattern of the vessels seem to unfold step by step under the local influence of earlier occurring morpho-histogenetic processes of the corresponding neural substratum.     

Modeling of the Dorsal Gradient across Species Reveals Interaction between Embryo Morphology and Toll Signaling Pathway during Evolution

Morphogenetic gradients are essential to allocate cell fates in embryos of varying sizes within and across closely related species. We previously showed that the maternal NF-κB/Dorsal (Dl) gradient has acquired different shapes in Drosophila species, which result in unequally scaled germ layers along the dorso-ventral axis and the repositioning of the neuroectodermal borders. Here we combined experimentation and mathematical modeling to investigate which factors might have contributed to the fast evolutionary changes of this gradient. To this end, we modified a previously developed model that employs differential equations of the main biochemical interactions of the Toll (Tl) signaling pathway, which regulates Dl nuclear transport. The original model simulations fit well the D. melanogaster wild type, but not mutant conditions. To broaden the applicability of this model and probe evolutionary changes in gradient distributions, we adjusted a set of 19 independent parameters to reproduce three quantified experimental conditions (i.e. Dl levels lowered, nuclear size and density increased or decreased). We next searched for the most relevant parameters that reproduce the species-specific Dl gradients. We show that adjusting parameters relative to morphological traits (i.e. embryo diameter, nuclear size and density) alone is not sufficient to reproduce the species Dl gradients. Since components of the Tl pathway simulated by the model are fast-evolving, we next asked which parameters related to Tl would most effectively reproduce these gradients and identified a particular subset. A sensitivity analysis reveals the existence of nonlinear interactions between the two fast-evolving traits tested above, namely the embryonic morphological changes and Tl pathway components. Our modeling further suggests that distinct Dl gradient shapes observed in closely related melanogaster sub-group lineages may be caused by similar sequence modifications in Tl pathway components, which are in agreement with their phylogenetic relationships.     

Loss of periostin occurs in aging adipose tissue of mice and its genetic ablation impairs adipose tissue lipid metabolism

Remodeling of the extracellular matrix is a key component of the metabolic adaptations of adipose tissue in response to dietary and physiological challenges. Disruption of its integrity is a well‐known aspect of adipose tissue dysfunction, for instance, during aging and obesity. Adipocyte regeneration from a tissue‐resident pool of mesenchymal stem cells is part of normal tissue homeostasis. Among the pathophysiological consequences of adipogenic stem cell aging, characteristic changes in the secretory phenotype, which includes matrix‐modifying proteins, have been described. Here, we show that the expression of the matricellular protein periostin, a component of the extracellular matrix produced and secreted by adipose tissue‐resident interstitial cells, is markedly decreased in aged brown and white adipose tissue depots. Using a mouse model, we demonstrate that the adaptation of adipose tissue to adrenergic stimulation and high‐fat diet feeding is impaired in animals with systemic ablation of the gene encoding for periostin. Our data suggest that loss of periostin attenuates lipid metabolism in adipose tissue, thus recapitulating one aspect of age‐related metabolic dysfunction. In human white adipose tissue, periostin expression showed an unexpected positive correlation with age of study participants. This correlation, however, was no longer evident after adjusting for BMI or plasma lipid and liver function biomarkers. These findings taken together suggest that age‐related alterations of the adipose tissue extracellular matrix may contribute to the development of metabolic disease by negatively affecting nutrient homeostasis.     

An immunohistochemical and morphometric study on astrocytes and microvas culature in the human cerebral cortex

In this study, astrocytes and microvessels of the human cerebral cortex were analysed morphometrically with the aim of acquiring quantitative information on the glio-vascular relationships, considered to be of great importance in the formation and functioning of the blood--brain barrier. Immunohistochemistry for the astrocytic marker, glial fibrillary acidic protein, was used with a computerized image analysis system. The brain tissue was embedded using the progressive lowering of temperature method, and the image analyser was applied to semithin sections subjected to immunogold--silver staining and viewed by epipolarization microscopy. The results show that, in the human cerebral cortex, astrocytes cover 11.4% of the cortex area and that their perivascular processes are nearly as extensive as the vascular bed (0.8% versus 1.72% of the cortex area). These processes form a virtually continuous sheath around the vascular walls, only 11% of the vessel perimeter lacking this astrocytic glia covering. The present results, compared with previous unpublished data obtained by conventional immunocytochemical procedures on wax sections, indicate that low-temperature methods combined with gold--silver immunolabelling on semithin sections significantly improve the detection of immunoreactivity and the performance of the image analyser. This revised version was published online in November 2006 with corrections to the Cover Date.     

Assessing the presence of abnormal regulation of cortisol secretion by membrane hormone receptors: in vivo and in vitro studies in patients with functioning and non-functioning adrenal adenoma.

Regulation of cortisol secretion by aberrant hormone receptors may play a role in the pathogenesis of ACTH-independent Cushing's syndrome. In this study, the topic was evaluated by combining in vivo and in vitro approaches. Cortisol responses to various stimuli (standard meal, GnRH + TRH, cisapride, vasopressin, glucagon) were assessed in 6 patients with clinical or subclinical adrenal Cushing's syndrome, and non-functioning adrenal adenoma in two cases. Abnormal responses were observed in three patients with Cushing's syndrome; one patient showed a gastric inhibitory polypeptide (GIP)-dependent cortisol rise after meal, together with responses after GnRH and cisapride; the second patient showed an LH-dependent cortisol response to GnRH, and in the third cortisol rose after cisapride. The pattern of receptor expression performed by RT-PCR showed that while GIP-R was only expressed in tumor from the responsive patient, 5-hydroxytryptamine type 4 receptor and LH-R were also present in normal adrenal tissues and tissues from non-responsive patients. Interestingly, an activating mutation of Gsalpha gene was identified in one of these tumors. Therefore, cortisol responses to agents operating via Gs protein coupled receptors (in one case associated with Gsalpha mutation) were found in Cushing's patients, while these responses were absent in the others. The finding of receptor expression in normal and non-responsive tumors suggests that different mechanisms are probably involved in inducing in vivo cortisol responses.     

Alkaloids of Lycopodium paniculatum: The structure of paniculine

Three new alkaloids isolated from Lycopodium paniculatum were identified as paniculine (7α-hydroxy-acetyldihydrolycopodine), deacetylpaniculine and anhydrodeacetylpaniculine. Other known alkaloids isolated include flabellidine, lycoclavine, together with deacetyllycoclavine previously obtained as a degradation product of lycoclavine.     

Alkaloids of Lycopodium magellanicum

Six alkaloids have been isolated from Lycopodium magellanicum. These include the known alkaloids lycopodine, acetyldihydrolycopodine, lycodine, N-methyllycodine, acetylfawcettine and a new alkaloid, 5-dehydro-magellanine. The chemical correlation of magellanine and paniculatine and the establishment of their absolute configuration are described.     

Ground-foraging ants (Hymenoptera: Formicidae) and rainfall effect on pitfall trapping in a deciduous thorn woodland (caatinga), Northeastern Brazil

The semi-arid Caatinga is the fourth largest biome of Brazil, which biota still remains one of the most poorly known, especially with regard to invertebrate groups. In this study, a ground-foraging ant assemblage was surveyed during one year and the effect of rainfall on pitfall trapping was assessed. The study was performed in an area located in the municipality of Pentecoste (3 degrees 48' S - 39 degrees 20' W), in the State of Ceará. A 200m transect with 20 equidistant sampling points was established. Transect sampling was performed once a month during 12 months, over the period August 2008-August 2009. At each sampling point, a pitfall trap partially filled with a mixture of ethanol and monoethylene glycol was placed at the beginning of each month and remained in the field for seven days. 39 species belonging to six subfamilies and 19 genera, plus two unidentified species, were collected, with Pheidole (10 spp.) and Camponotus (8 spp.) being the taxa with the most species. 23 species were frequent, being found in more than 50% of the 12 transect samplings. Five species had an intermediate frequency (25 to 50%), while 13 were relatively infrequent (less than 25%). Most of the species (22) showed low occurrence, being found in less than 10% of the 240 samples (20 samples each month, during 12 months). Only five species were collected in more than 50% of the samples, those species being also responsible for most of the total abundance (number of captured individuals of all species) observed each month. The species-accumulation curves (observed and estimated) indicated that sampling sufficiency was attained, and that about 92% of the estimated ground-foraging ant fauna had been collected. 40 and 29 species were collected in the dry and rainy season, respectively, with monthly species richness ranging from 13 to 28. The total ant abundance showed a drastic decrease during the rainy season, and a negative linear correlation was found between rainfall and total ant abundance (R2 = 0.68). A similar negative linear correlation was found for species occurrences against rainfall (R2 = 0.71), and for mean number of species per pitfall trap against rainfall (R2 = 0.71). However, some species showed equal abundance, occurrence and mean number of individuals per pitfall trap in both seasons, while others showed a much higher abundance and occurrence during the rainy season. Pitfall trapping as a method to sample ground-foraging ant assemblage of the Caatinga biome and potential factors responsible for lower pitfall trap performance during rainy season are discussed.     

Correlation between koilocytes and human papillomavirus detection by PCR in oral and oropharynx squamous cell carcinoma biopsies

The purpose of this study was to compare the histopathological analysis with polymerase chain reaction (PCR) methods to predict the presence of human papillomavirus (HPV) infection in oral squamous cell carcinoma biopsies. Eighty-three paraffin-embedded tissue specimens from patients with oropharynx and mouth floor squamous cell carcinoma were submitted to histopathological analysis under light microscopy, specifically for the determination of the presence of koilocytes. Subsequently, DNA was purified from the same paraffin-embedded specimens and submitted to PCR. Fisher's exact test showed no statistically significant correlation between the two methods. The results suggest that the presence of koilocytes is unreliable for the detection of HPV presence in oral and oropharynx squamous cell carcinoma.