Steviol effect, a glycoside of Stevia rebaudiana, on glucose clearances in rats

Stevia rebaudiana, a South American plant normally used as a natural herbal sweetener, has been suggested as exerting beneficial effects on human health, including as an antihypertensive and antihyperglycemic. The present experiment was undertaken to evaluate the renal excretion of steviol, the aglycone of several natural products extracted from the leaves of S. rebaudiana, and to clarify the actual participation of this compound on the renal excretion of glucose in rats, which has been previously suggested as the preferential action of steviol on the Na+-glucose renal tubular transport system. Steviol was obtained by enzymatic hydrolysis of stevioside with pectinase. Thirty normal male Wistar rats weighing 345 g were used. After a control period, steviol was infused iv at three doses (0.5, 1.0 and 3.0 mg.kg-1/h), according to classical clearance techniques. During all the experiments no significant changes in inulin clearance (Cin) and p-aminohipuric acid clearance (C PAH) were observed. Administration of steviol resulted in a statistically significant increase in the fractional sodium excretion (FeNa+), fractional potassium excretion (FeK+), urinary flow as percent of glomerular filtration rate (V/GFR) and glucose clearance (C G) when compared to controls, but these effects were absent with the dose of 0.5 mg.kg-1/h. The steviol clearance (C S) was higher than the Cin and lower than the C PAH at all the doses employed in this study. The data suggest that steviol is secreted by renal tubular epithelium, causing diuresis, natriuresis, kaliuresis and a fall in renal tubular reabsorption of glucose.

Avaliação morfológica das membranas fetais e da placenta de Mazama gouazoubira (veado-catingueiro) de vida livre no terço inicial da gestação

Mazama gouazoubira, o veado-catingueiro, é uma espécie de cervídeo de porte pequeno, que pode ser encontrado na América do Sul, desde o sul do Uruguai até o norte de Mato Grosso, no Brasil. Este estudo teve como objetivo descrever as membranas fetais e a placenta de M. gouazoubira no terço inicial de gestação. As amostras coletadas foram analisadas macroscopicamente e microscopicamente. O exame do útero demonstrou uma gestação univitelina e um embrião com crown-rump de 13mm. Na análise do embrião pode ser observado o olho pigmentado, as saliências auriculares, o mesonefro e e metanefro em desenvolvimento, o fígado e sua proeminência externa, o estômago, os membros torácicos e os brotos dos membros pélvicos. A placenta apresentou-se oligocotiledonária e no útero puderam ser observadas nove carúnculas. O saco gestacional mediu 15cm de comprimento e, como observado no início da gestação dos ruminantes domésticos, os cotilédones não puderam ser identificados macroscopicamente. Uma fraca adesão foi observada entre as carúnculas e a membrana corioalantóica (cotilédones) que formavam os placentônios. A membrana corioalantóica demonstrou um alantóide bem vascularizado composto por uma fina camada de células de núcleos e citoplasmas alongados. Na outra face da membrana, o cório foi composto por células cúbicas, de citoplasmas escassos e núcleos grandes e arredondados, características de células trofoblásticas. Envolvendo o embrião visualizou-se o saco amniótico constituído de duas camadas passíveis de separação mecânica, que apresentaram morfologia similar, sendo formadas por um epitélio pavimentoso avascular. Não foi observado saco vitelino no estágio gestacional do espécime estudado. Conclui-se que a placenta de M. gouazoubira é oligocotiledonária, como observado em outros cervídeos, e que as membranas fetais apresentam semelhanças com a de outros ruminantes, incluindo as características citológicas. Estudos adicionais são necessários para determinar a presença do saco vitelino e quando ocorre sua regressão.

Análise proliferativa nas células trofoblásticas em bovinos

The aim of the present study was to evaluate the cell proliferative activity, by AgNORs number, in different regions of bovine placenta throughout gestation. A total of 28 bovine placentas were separated into four groups: group I (60 to 120 days), group II (121 to 170 days), group III (171 to 220 days), and group IV (221 to 290 days). It was found a greater number of AgNORs in giant trophoblastic cells (GTC) when compared with mononuclear trophoblastic cells (MTC) (p<0,001) in all regions and gestational groups analyzed, that confirms their intensive synthesis activity in trophoblast epithelium. The central region of the placentome begins an intense proliferative activity in group II, observed by clusters, while placentomes edges showed a higher number of clusters on group III. These data suggest that the central region of the placentomes began an intense proliferative activity prior to its edge, both declines at the end of pregnancy. Interplacentomal area showed a higher number of AgNORs in the group IV, suggesting a higher proliferative activity of these cells at the end of pregnancy. The results of this study indicate that the proliferative activity, as determined by the amount of intranuclear AgNORs, exhibits patterns that are not only specific to each type of trophoblastic cells, but also for each specific region of bovine placenta throughout pregnancy.

Análise morfométrica da transição esôfago-gástrica de eqüinos submetidos a diferentes manejos alimentares e atividade física

O objetivo deste trabalho foi identificar se diferentes tipos de manejo físico e alimentar determinaram mudanças adaptativas na morfometria da região de transição esôfago-gástrica (TEG) em eqüinos. Foram utilizados 15 conjuntos de animais adultos com raça, sexo e idade não identificados, divididos em três grupos de acordo com a dieta e a atividade física: grupo I - composto por cinco conjuntos da TEG de eqüinos em treinamento intensivo e alimentados principalmente à base de concentrado; grupo II - com cinco conjuntos da TEG de eqüinos que não desempenhavam atividade física intensa e eram alimentados principalmente à base de concentrado, e o grupo III - composto por cinco conjuntos da TEG de eqüinos mantidos a pasto e que não desempenhavam atividade física intensa. A região de transição esôfago-gástrica teve a estrutura do seu epitélio avaliada morfometricamente, onde foram feitas mensurações para identificar a espessura do epitélio estratificado pavimentoso queratinizado. A espessura do grupo I teve como média 122,3µm, do grupo II foi de 173,4µm e do grupo III foi de 281,7µm. Os resultados encontrados para a espessura do epitélio estratificado pavimentoso queratinizado dos eqüinos mostraram a existência de diferenças estatisticamente significativas dos eqüinos do grupo I, quando comparados aos eqüinos do grupo III.

Morfologia dos órgãos genitais masculinos e da cloaca da ema (Rhea americana americana)

As características morfológicas, macroscópicas e microscópicas, dos órgãos genitais masculinos e da cloaca foram analisados em 23 emas, quatro filhotes (duas semanas), sete jovens (de três a oito meses) e doze adultos (três anos), provenientes da Cooperativa Emas do Brasil, RS, e do CEMAS, Mossoró, RN. Os testículos da ema possuem formato alongado e localizam-se na cavidade celomática, na região intra-abdominal dorsal, com comprimento e larguras médias de 7,6±1,2cm e 2,6± 0,7cm nos adultos; 4,5±1,5cm e 0,9±0,4cm nos jovens; e 0,8±0,3cm, e 0,2±0,1cm nos filhotes. O testículo está envolto pela túnica albugínea e seu parênquima possui túbulos seminíferos irregulares, compostos por epitélio espermatogênico e por células de sustentação, e pelo tecido intersticial, com as células endócrinas intersticiais, tecido conjuntivo frouxo e vasos. Nos adultos observaram-se todas as células da linhagem espermatogênica, enquanto nos jovens com 3 meses, os testículos apresentaram túbulos seminíferos com luz reduzidas, espermatogônias e células de sustentação indiferenciadas. Os ductos eferentes possuem um epitélio cúbico ciliado, enquanto no ducto epididimário o epitélio é columnar. O epidídimo apresentou-se alongado e fusiforme junto a margem medial do testículo. O ducto deferentes apresentou trajeto sinuoso nos adultos, retilíneo nos jovens, convoluto na sua porção média, diminuindo seu formato sigmóide em sua porção caudal, próximo à cloaca. O epitélio é pseudoestratificado e reveste a luz irregular nos adultos e circular nos jovens, mantendo proximidade com o ureter. A cloaca dividiu-se em três segmentos: o coprodeu, o urodeo e o proctodeo. No urodeu os ductos deferentes desembocaram em papilas na parede ventro-lateral, próximo a inserção do falo fibroso. O falo é um órgão fibroso linfático, localizado na parede ventral, no assoalho da cloaca, e apresentou duas porções: uma rígida bifurcada e contorcida, e outra simples espiralada e flexível, a qual normalmente esteve invertida. Em exposição forçada, o falo teve 14 cm de comprimento. De forma geral os órgãos reprodutores das emas compartilharam da morfologia de outras aves, principalmente aquelas descritas para os avestruzes.

Morphology of the male agouti accessory genital glands (Dasyprocta prymnolopha Wagler, 1831)

The morphology of the accessory genital glands of the male agouti was studied in twenty-three animals that were raised in captivity. Twenty animals had their genital glands dissected in situ for macroscopic description. The samples of each gland were recovered, embedded in paraffin, sliced and stained by Hematoxylin-Eosin technique. It was founded four pairs of glands: the vesicular glands, the coagulating glands, the prostate and the bulbourethral glands. Histological characteristics of the vesicular, coagulating and prostate glands showed similar morphology, within the pseudostratified columnar epithelium. The tubulo-alveolar type of the bulbourethral glands showed a lack of connective tissue among the tubules, a small amount of red stained presented it the cytoplasm, and the presence of vacuoles in the tissue. This study concluded that the agouti showed to have similar morphological aspect described in the others species of rodents.

Achados clínico patológicos durante um surto de disenteria de inverno em bovinos no Rio Grande do Sul

Descreve-se um surto de disenteria de inverno que afetou 10 vacas leiteiras de uma propriedade localizada em Viamão, Rio Grande do Sul. O quadro clínico caracterizou-se por uma diarréia inicialmente líquida esverdeada com estrias de sangue e muco, evoluindo, em alguns animais, para uma diarréia de coloração marrom escura à sanguinolenta, que persistiu, em média, cinco dias. Drástica diminuição na produção de leite e no consumo de alimentos, além de graus variados de depressão também foram observados. Apenas um dos 10 animais afetados morreu. Durante a necropsia, observaram-se mucosas pálidas, conteúdo sanguinolento com presença de grande quantidade de coágulos, principalmente no cólon espiral e petéquias na mucosa do cólon. Os principais achados histológicos foram encontradas no cólon espiral, onde havia criptas dilatadas, sem epitélio de revestimento ou revestidas por epitélio pavimentoso e/ou cuboidal, por vezes com núcleos grandes e nucléolos proeminentes. Algumas criptas eram preenchidas por debris necróticos e polimorfonucleares. Na imuno-histoquímica com anticorpo monoclonal para coronavírus bovino (8F2) em cortes do cólon espiral, havia marcações positivas no citoplasma de enterócitos das criptas, nos debris necróticos destas e em macrófagos na lâmina própria.

Spectral Region Optimization for Raman-Based Optical Biopsy of Inflammatory Lesions

Objective: The biochemical alterations between inflammatory fibrous hyperplasia (IFH) and normal tissues of buccal mucosa were probed by using the FT-Raman spectroscopy technique. The aim was to find the minimal set of Raman bands that would furnish the best discrimination. Background: Raman-based optical biopsy is a widely recognized potential technique for noninvasive real-time diagnosis. However, few studies had been devoted to the discrimination of very common subtle or early pathologic states as inflammatory processes that are always present on, for example, cancer lesion borders. Methods: Seventy spectra of IFH from 14 patients were compared with 30 spectra of normal tissues from six patients. The statistical analysis was performed with principal components analysis and soft independent modeling class analogy cross-validated, leave-one-out methods. Results: Bands close to 574, 1,100, 1,250 to 1,350, and 1,500 cm(-1) (mainly amino acids and collagen bands) showed the main intragroup variations that are due to the acanthosis process in the IFH epithelium. The 1,200 (C-C aromatic/DNA), 1,350 (CH(2) bending/collagen 1), and 1,730 cm(-1) (collagen III) regions presented the main intergroup variations. This finding was interpreted as originating in an extracellular matrix-degeneration process occurring in the inflammatory tissues. The statistical analysis results indicated that the best discrimination capability (sensitivity of 95% and specificity of 100%) was found by using the 530-580 cm(-1) spectral region. Conclusions: The existence of this narrow spectral window enabling normal and inflammatory diagnosis also had useful implications for an in vivo dispersive Raman setup for clinical applications.

A scientific note: Foragers deposit attractive scent marks in a stingless bee that does not communicate food location

National Science Foundation NSF IBN[0316697]

Active Dendrites Enhance Neuronal Dynamic Range

Since the first experimental evidences of active conductances in dendrites, most neurons have been shown to exhibit dendritic excitability through the expression of a variety of voltage-gated ion channels. However, despite experimental and theoretical efforts undertaken in the past decades, the role of this excitability for some kind of dendritic computation has remained elusive. Here we show that, owing to very general properties of excitable media, the average output of a model of an active dendritic tree is a highly non-linear function of its afferent rate, attaining extremely large dynamic ranges (above 50 dB). Moreover, the model yields double-sigmoid response functions as experimentally observed in retinal ganglion cells. We claim that enhancement of dynamic range is the primary functional role of active dendritic conductances. We predict that neurons with larger dendritic trees should have larger dynamic range and that blocking of active conductances should lead to a decrease in dynamic range.

Mucin pattern reflects the origin of the adenocarcinoma in Barrett's esophagus: a retrospective clinical and laboratorial study

Background: Mucin immunoexpression in adenocarcinoma arising in Barrett's esophagus (BE) may indicate the carcinogenesis pathway. The aim of this study was to evaluate resected specimens of adenocarcinoma in BE for the pattern of mucins and to correlate to the histologic classification. Methods: Specimens were retrospectively collected from thirteen patients who underwent esophageal resection due to adenocarcinoma in BE. Sections were scored for the grade of intestinal metaplasia. The tissues were examined by immunohistochemistry for MUC2 and MUC5AC antibodies. Results: Eleven patients were men. The mean age was 61 years old (varied from 40 to 75 years old). The tumor size had a mean of 4.7 +/- 2.3 cm, and the extension of BE had a mean of 7.7 +/- 1.5 cm. Specialized epithelium with intestinal metaplasia was present in all adjacent mucosas. Immunohistochemistry for MUC2 showed immunoreactivity in goblet cells, while MUC5AC was extensively expressed in the columnar gastric cells, localizing to the surface epithelium and extending to a variable degree into the glandular structures in BE. Tumors were classified according to the mucins in gastric type in 7/13 (MUC5AC positive) and intestinal type in 4/13 (MUC2 positive). Two tumors did not express MUC2 or MUC5AC proteins. The pattern of mucin predominantly expressed in the adjacent epithelium was associated to the mucin expression profile in the tumors, p = 0.047. Conclusion: Barrett's esophagus adenocarcinoma shows either gastric or intestinal type pattern of mucin expression. The two types of tumors developed in Barrett's esophagus may reflect the original cell type involved in the malignant transformation.

Epigenetic Silencing of CRABP2 and MX1 in Head and Neck Tumors

Head and neck squamous cell carcinoma (HNSCC) is a heterogeneous disease affecting the epithelium of the oral cavity, pharynx and larynx. Conditions of most patients are diagnosed at late stages of the disease, and no sensitive and specific predictors of aggressive behavior have been identified yet. Therefore, early detection and prognostic biomarkers are highly desirable for a more rational management of the disease. Hypermethylation of CpG islands is one of the most important epigenetic mechanisms that leads to gene silencing in tumors and has been extensively used for the identification of biomarkers. In this study, we combined rapid subtractive hybridization and microarray analysis in a hierarchical manner to select genes that are putatively reactivated by the demethylating agent 5-aza-2'-deoxycytidine (5Aza-dC) in HNSCC cell lines (FaDu, UM-SCC-14A, UM-SCC-17A, UM-SCC-38A). This combined analysis identified 78 genes, 35 of which were reactivated in at least 2 cell lines and harbored a CpG island at their 5' region. Reactivation of 3 of these 35 genes (CRABP2, MX1, and SLC15A3) was confirmed by quantitative real-time polymerase chain reaction (PCR; fold change, >= 3). Bisulfite sequencing of their CpG islands revealed that they are indeed differentially methylated in the HNSCC cell lines. Using methylation-specific PCR, we detected a higher frequency of CRABP2 (58.1% for region 1) and MX1 (46.3%) hypermethylation in primary HNSCC when compared with lymphocytes from healthy individuals. Finally, absence of the CRABP2 protein was associated with decreased disease-free survival rates, supporting a potential use of CRABP2 expression as a prognostic biomarker for HNSCC patients.

RNA interference-mediated knockdown of CD49e (alpha 5 integrin chain) in human thymic epithelial cells modulates the expression of multiple genes and decreases thymocyte adhesion

Background: The thymus is a central lymphoid organ, in which bone marrow-derived T cell precursors undergo a complex process of maturation. Developing thymocytes interact with thymic microenvironment in a defined spatial order. A component of thymic microenvironment, the thymic epithelial cells, is crucial for the maturation of T-lymphocytes through cell-cell contact, cell matrix interactions and secretory of cytokines/chemokines. There is evidence that extracellular matrix molecules play a fundamental role in guiding differentiating thymocytes in both cortical and medullary regions of the thymic lobules. The interaction between the integrin alpha 5 beta 1 (CD49e/CD29; VLA-5) and fibronectin is relevant for thymocyte adhesion and migration within the thymic tissue. Our previous results have shown that adhesion of thymocytes to cultured TEC line is enhanced in the presence of fibronectin, and can be blocked with anti-VLA-5 antibody. Results: Herein, we studied the role of CD49e expressed by the human thymic epithelium. For this purpose we knocked down the CD49e by means of RNA interference. This procedure resulted in the modulation of more than 100 genes, some of them coding for other proteins also involved in adhesion of thymocytes; others related to signaling pathways triggered after integrin activation, or even involved in the control of F-actin stress fiber formation. Functionally, we demonstrated that disruption of VLA-5 in human TEC by CD49e-siRNA-induced gene knockdown decreased the ability of TEC to promote thymocyte adhesion. Such a decrease comprised all CD4/CD8-defined thymocyte subsets. Conclusion: Conceptually, our findings unravel the complexity of gene regulation, as regards key genes involved in the heterocellular cell adhesion between developing thymocytes and the major component of the thymic microenvironment, an interaction that is a mandatory event for proper intrathymic T cell differentiation.

SOFT TISSUE INTEGRATION IN THE NECK AREA OF TITANIUM IMPLANTS - AN ANIMAL TRIAL

Dental implant materials are required to enable good apposition of bone and soft tissues. They must show sufficient resistance to chemical, physical and biological stress in the oral cavity to achieve good long-term outcomes. A critical issue is the apposition of the soft tissues, as they have provided a quasi-physiological closure of oral cavity. The present experiment was performed to study the peri-implant tissue response to non-submerged (1-stage) implant installation procedures. Two different implants types (NobelBiocare, NobelReplace (R) Tapered Groovy 4.3 x 10 mm and Replace (R) Select Tapered TiU RP 4.3 x 10 mm) were inserted into the right and left sides of 8 domestic pigs (Sus scrofa domestica) mandibles, between canines and premolars and immediately provided with a ceramic crown. Primary implant stability was determined using ressonance frequency analysis. Soft tissue parameters were assessed: sulcus depth (SDI) and junctional epithelium (JE). Following 70 days of healing, jaw sections were processed for histology and histomorphometric examination. Undecalcified histological sections demonstrated osseointegration with direct bone contact. The soft tissue parameters revealed no significant differences between the two implant types. The peri-implant soft tissues appear to behave similarly in both implant types.

Structure of an Odorant-Binding Protein from the Mosquito Aedes aegypti Suggests a Binding Pocket Covered by a pH-Sensitive ""Lid""

Background: The yellow fever mosquito, Aedes aegypti, is the primary vector for the viruses that cause yellow fever, mostly in tropical regions of Africa and in parts of South America, and human dengue, which infects 100 million people yearly in the tropics and subtropics. A better understanding of the structural biology of olfactory proteins may pave the way for the development of environmentally-friendly mosquito attractants and repellents, which may ultimately contribute to reduction of mosquito biting and disease transmission. Methodology: Previously, we isolated and cloned a major, female-enriched odorant-binding protein (OBP) from the yellow fever mosquito, AaegOBP1, which was later inadvertently renamed AaegOBP39. We prepared recombinant samples of AaegOBP1 by using an expression system that allows proper formation of disulfide bridges and generates functional OBPs, which are indistinguishable from native OBPs. We crystallized AaegOBP1 and determined its three-dimensional structure at 1.85 angstrom resolution by molecular replacement based on the structure of the malaria mosquito OBP, AgamOBP1, the only mosquito OBP structure known to date. Conclusion: The structure of AaegOBP1 (= AaegOBP39) shares the common fold of insect OBPs with six alpha-helices knitted by three disulfide bonds. A long molecule of polyethylene glycol (PEG) was built into the electron-density maps identified in a long tunnel formed by a crystallographic dimer of AaegOBP1. Circular dichroism analysis indicated that delipidated AaegOBP1 undergoes a pH-dependent conformational change, which may lead to release of odorant at low pH (as in the environment in the vicinity of odorant receptors). A C-terminal loop covers the binding cavity and this ""lid"" may be opened by disruption of an array of acid-labile hydrogen bonds thus explaining reduced or no binding affinity at low pH.