A Biologia e a Matemática vistas com as mãos e com os olhos através do croché

O croché, a arte de puxar laçadas de fio através de loops com a ajuda de uma agulha em gancho, é uma técnica muito promissora no desenvolvimento de competências e na transmissão de conceitos. Por um lado, permite o aperfeiçoamento da motricidade fina, bem como da flexibilidade de raciocínio e do pensamento lógico. Por outro, viabiliza a construção de modelos tridimensionais manipuláveis, representativos de conceitos em diversas áreas científicas como a Biologia e a Matemática. Talvez o caso mais icónico seja o da criação de modelos físicos de espaços hiperbólicos, avançado pela primeira vez por Daina Taimina, em 1997 (1). É, até hoje, a única técnica capaz de representar, a três dimensões, as propriedades da geometria hiperbólica patente no mundo vivo, por exemplo, no padrão de crescimento dos corais e de diversas plantas. Foi, inspirando-se neste trabalho, que o projecto STOL – Science Through Our Lives, recriou um recife de corais em croché denominado “Ponto a Ponto Enche a Ciência o Espaço” (2), numa lógica WIP (Work in Progress), que já pôde ser visto em diversos locais do país e que está associado a uma oficina de carácter hands on. Mais recentemente, a equipa STOL produziu, em croché, modelos de plantas – fractal, por exemplo fetos, que estão a ser usados para transmitir conceitos matemáticos de geometria fractal e auto-semelhança, na oficina ’Matemática das Plantas’ proposta pelo Museu Nacional de História Natural e da Ciência da Universidade de Lisboa (MUHNAC) que, a partir do seu património único (3) no centro da cidade, integra estratégias participativas na sua oferta educativa. Recorrendo a uma pedagogia baseada em hands on, surge o questionamento: o que dizem estes crochés curiosos? As metodologias de Aprendizagem Activa no Ensino das Ciências – IBSE (Inquiry Based Science Education) - explicam porque é importante questionar (4). A partir de estruturas naturais do jardim e outros objectos como os produzidos no âmbito desta parceria feliz entre o STOL e o MUHNAC, quer-se levar o participante a questionar aspectos da Matemática e da Biologia.info:eu-repo/semantics/publishedVersio

Long photoperiods sustain high pH in Arctic kelp forests

Concern on the impacts of ocean acidification on calcifiers, such as bivalves, sea urchins, and foraminifers, has led to efforts to understand the controls on pH in their habitats, which include kelp forests and seagrass meadows. The metabolism of these habitats can lead to diel fluctuation in pH with increases during the day and declines at night, suggesting no net effect on pH at time scales longer than daily. We examined the capacity of subarctic and Arctic kelps to up-regulate pH in situ and experimentally tested the role of photoperiod in determining the capacity of Arctic macrophytes to up-regulate pH. Field observations at photoperiods of 15 and 24 hours in Greenland combined with experimental manipulations of photoperiod show that photoperiods longer than 21 hours, characteristic of Arctic summers, are conducive to sustained up-regulation of pH by kelp photosynthesis. We report a gradual increase in pH of 0.15 units and a parallel decline in pCO2 of 100 parts per million over a 10-day period in an Arctic kelp forest over midsummer, with ample scope for continued pH increase during the months of continuous daylight. Experimental increase in CO2 concentration further stimulated the capacity of macrophytes to deplete CO2 and increase pH. We conclude that long photoperiods in Arctic summers support sustained up-regulation of pH in kelp forests, with potential benefits for calcifiers, and propose that this mechanism may increase with the projected expansion of Arctic vegetation in response to warming and loss of sea ice.The study was funded by the Danish Environmental Protection Agency within the Danish Cooperation for Environment in the Arctic. It is also a contribution to the Greenland Ecosystem Monitoring program (www.G-E-M.dk) and the Arctic Science Partnership (www.asp-net.org). M.S.-M. was supported by a Fundación “La Caixa” fellowship (Spain). We acknowledge support by the CSIC Open Access Publication Initiative through its Unit of Information Resources for Research (URICI).Peer reviewe

Upregulation of natural killer cells functions underlies the efficacy of intratumorally injected dendritic cells engineered to produce interleukin-12

OBJECTIVE: Injection of dendritic cells (DC) engineered with recombinant adenoviral vectors to produce interleukin-12 (IL-12) inside experimental murine tumors frequently achieves complete regressions. In such a system the function of CD8(+) T cells has been shown to be an absolute requirement, in contrast to observations made upon depletion of CD4(+) T cells, which minimally affected the outcome. The aim of this work was to study the possible involvement of natural killer (NK) cells in this setting. MATERIALS, METHODS, AND RESULTS: Depletions with anti-AsialoGM1 antiserum showed only a small decrease in the proportion of complete regressions obtained that correlated with induction of NK activities in lymphatic tissues into which DC migrate, whereas combined depletions of CD4(+) and NK cells completely eliminated the antitumor effects. Likewise in vivo neutralization of interferon-gamma (IFN-gamma) also eliminated those therapeutic effects. Trying to define the cellular role played by NK cells in vivo, it was observed that injection of cultured DC inside the spleen of T- and B-cell-deficient (Rag1(-/-)) mice induced upregulation of NK activity only if DC had been adenovirally engineered to produce IL-12. In addition, identically transfected fibroblasts also activated NK cells, indicating that IL-12 transfection was the unique requirement. Equivalent human DC only activated in vitro the cytolytic and cytokine-secreting functions of autologous NK cells if transfected to express human IL-12. CONCLUSIONS: Overall, these results point out an important role played by NK cell activation in the potent immunotherapeutic effects elicited by intratumoral injection of IL-12--secreting DC and that NK activation under these conditions is mainly, if not only, dependent on IL-12

Thrombopenic purpura induced by a monoclonal antibody directed to a 35-kilodalton surface protein (p35) expressed on murine platelets and endothelial cells

OBJECTIVE: With the aim of obtaining monoclonal antibodies (mAbs) against mouse endothelial surface antigens, immunization of rats with a mouse-derived endothelial cell line (PY4.1) and subsequent hybridoma production were performed. MATERIALS AND METHODS: One of the mAbs produced by hybridoma EOL5F5 was selected for its surface binding to endothelial cell lines, and identification of the mAb-recognized antigen was performed by immunoprecipitation. Experiments were performed to analyze the effects of EOL5F5 on systemic administration to mice. RESULTS: EOL5F5-recognized antigen was a single band of 35 kDa under reducing and nonreducing conditions, features that do not match other known differentiation antigens with comparable tissue distribution. In vivo administration of purified EOL5F5 mAb to mice (n = 20) induced intense cutaneous purpura as well as severe but transient thrombocytopenia. Expression of EOL5F5-recognized antigen was detected on platelets from which it immunoprecipitated a moiety of identical electrophoretic pattern in SDS-PAGE, as the one recognized on endothelial cells. Immunohistochemically, EOL5F5-recognized antigen (p35) also was expressed on dermal capillaries, suggesting that, in addition to thrombocytopenia, damaging effects of the antibody on endothelial cells also might cause the observed purpura. CONCLUSIONS: Our results show induction of thrombocytopenic purpura in mice with an mAb against a single antigenic determinant expressed on both platelets and endothelium. EOL5F5 mAb injection sets the stage for useful experimental models that resemble immune thrombocytopenic purpura

Intratumoral injection of bone-marrow derived dendritic cells engineered to produce interleukin-12 induces complete regression of established murine transplantable colon adenocarcinomas

Stimulation of the antitumor immune response by dendritic cells (DC) is critically dependent on their tightly regulated ability to produce interleukin-12 (IL-12). To enhance this effect artificially, bone marrow (BM)-derived DC were genetically engineered to produce high levels of functional IL-12 by ex vivo infection with a recombinant defective adenovirus (AdCMVIL-12). DC-expressing IL-12 injected into the malignant tissue eradicated 50-100% well established malignant nodules derived from the injection of two murine colon adenocarcinoma cell lines. Successful therapy was dependent on IL-12 transfection and was mediated only by syngeneic, but not allogeneic BM-derived DC, indicating that compatible antigen-presenting molecules were required. The antitumor effect was inhibited by in vivo depletion of CD8+ T cells and completely abrogated by simultaneous depletion with anti-CD4 and anti-CD8 mAbs. Mice which had undergone tumor regression remained immune to a rechallenge with tumor cells, showing the achievement of long-lasting systemic immunity that also was able to reject simultaneously induced concomitant untreated tumors. Tumor regression was associated with a detectable CTL response directed against tumor-specific antigens probably captured by DC artificially released inside tumor nodules. Our results open the possibility of similarly treating the corresponding human malignancies

Continuous daylight in the high-Arctic summer supports high plankton respiration rates compared to those supported in the dark

Plankton respiration rate is a major component of global CO2 production and is forecasted to increase rapidly in the Arctic with warming. Yet, existing assessments in the Arctic evaluated plankton respiration in the dark. Evidence that plankton respiration may be stimulated in the light is particularly relevant for the high Arctic where plankton communities experience continuous daylight in spring and summer. Here we demonstrate that plankton community respiration evaluated under the continuous daylight conditions present in situ, tends to be higher than that evaluated in the dark. The ratio between community respiration measured in the light (Rlight) and in the dark (Rdark) increased as the 2/3 power of Rlight so that the Rlight:Rdark ratio increased from an average value of 1.37 at the median Rlight measured here (3.62 µmol O2 L-1 d-1) to an average value of 17.56 at the highest Rlight measured here (15.8 µmol O2 L-1 d-1). The role of respiratory processes as a source of CO2 in the Arctic has, therefore, been underestimated and is far more important than previously believed, particularly in the late spring, with 24 h photoperiods, when community respiration rates are highest

Study of comparative bioavailability among two formulations containing hydroxyzine hydrochloride in healthy volunteers after a single dose administration

The study was performed to compare the bioavailability of two hydroxyzine hydrochloride 25 mg tablet formulation in 16 volunteers of both sexes. The study was conducted open with randomized two period crossover design and a two weeks wash out period. Plasma samples were obtained over a 96 h interval. Hydroxyzine concentrations were analyzed by Liquid Chromatography with Tandem Mass Spectrometry (LC-MS/MS). Bioequivalence between the products was determined by calculating 90 % confidence intervals (90 % I.C) for the ratio of AUC0-t , AUC0-inf and Cmax values for the test and reference products, using logarithmic transformed data. The 90 % confidence intervals were 81.89-105.85 %, 84.61-105.30 %, and 84.04-108.66 %, respectively. Since the 90 % confidence intervals for Cmax , AUC0-t and AUC0-inf were within the 80-125 % interval proposed by the Food and Drug Administration, it was concluded that the two hydroxyzine hydrochloride formulations are bioequivalent in their rate and extent of absorption.Colegio de Farmacéuticos de la Provincia de Buenos Aire

Study of comparative bioavailability among two formulations containing hydroxyzine hydrochloride in healthy volunteers after a single dose administration

The study was performed to compare the bioavailability of two hydroxyzine hydrochloride 25 mg tablet formulation in 16 volunteers of both sexes. The study was conducted open with randomized two period crossover design and a two weeks wash out period. Plasma samples were obtained over a 96 h interval. Hydroxyzine concentrations were analyzed by Liquid Chromatography with Tandem Mass Spectrometry (LC-MS/MS). Bioequivalence between the products was determined by calculating 90 % confidence intervals (90 % I.C) for the ratio of AUC0-t , AUC0-inf and Cmax values for the test and reference products, using logarithmic transformed data. The 90 % confidence intervals were 81.89-105.85 %, 84.61-105.30 %, and 84.04-108.66 %, respectively. Since the 90 % confidence intervals for Cmax , AUC0-t and AUC0-inf were within the 80-125 % interval proposed by the Food and Drug Administration, it was concluded that the two hydroxyzine hydrochloride formulations are bioequivalent in their rate and extent of absorption.Colegio de Farmacéuticos de la Provincia de Buenos Aire

Improving efficacy of interleukin-12-transfected dendritic cells injected into murine colon cancer with anti-CD137 monoclonal antibodies and alloantigens

Intralesional administration of cultured dendritic cells (DCs) engineered to produce IL-12 by in vitro infection with recombinant adenovirus frequently displays eradicating efficacy against established subcutaneous tumors derived from the CT26 murine colon carcinoma cell line. The elicited response is mainly mediated by cytolytic T lymphocytes. In order to search for strategies that would enhance the efficacy of the therapeutic procedure against less immunogenic tumors, we moved onto malignancies derived from the inoculation of MC38 colon cancer cells that are less prone to undergo complete regression upon a single intratumoral injection of IL-12-secreting DCs. In this model, we found that repeated injections of such DCs, as opposed to a single injection, achieved better efficacy against both the injected and a distantly implanted tumor; that the use of semiallogeneic DCs that are mismatched in one MHC haplotype with the tumor host showed slightly better efficacy; and that the combination of this treatment with systemic injections of immunostimulatory anti-CD137 (4-1BB) monoclonal antibody achieved potent combined effects that correlated with the antitumor immune response measured in IFN-gamma ELISPOT assays. The elicited systemic immune response eradicates concomitant untreated lesions in most cases. Curative efficacy was also found against some tumors established for 2 weeks when these strategies were used in combination. These are preclinical pieces of evidence to be considered in order to enhance the therapeutic benefit of a strategy that is currently being tested in clinical trials. Supplementary Material for this article can be found on the International Journal of Cancer website at http://www.interscience.wiley.com/jpages/0020-7136/suppmat/index.html

Characterization of the complete mitochondrial genome and a set of polymorphic microsatellite markers through next-generation sequencing for the brown brocket deer Mazama gouazoubira

The complete mitochondrial genome of the brown brocket deer Mazama gouazoubira and a set of polymorphic microsatellite markers were identified by 454-pyrosequencing. De novo genome assembly recovered 98% of the mitochondrial genome with a mean coverage of 9-fold. The mitogenome consisted of 16,356 base pairs that included 13 protein-coding genes, two ribosomal subunit genes, 22 transfer RNAs and the control region, as found in other deer. The genetic divergence between the mitogenome described here and a previously published report was ∼0.5%, with the control region and ND5 gene showing the highest intraspecific variation. Seven polymorphic loci were characterized using 15 unrelated individuals; there was moderate genetic variation across most loci (mean of 5.6 alleles/locus, mean expected heterozygosity = 0.70), with only one locus deviating significantly from Hardy-Weinberg equilibrium, probably because of null alleles. Marker independence was confirmed with tests for linkage disequilibrium. The genetic variation of the mitogenome and characterization of microsatellite markers will provide useful tools for assessing the phylogeography and population genetic patterns in M. gouazoubira, particularly in the context of habitat fragmentation in South America