A review on the role of duckweed in nutrient reclamation and as a source of animal feed

The family of lemnacae colloquially known as duckweed contains the world's smallest species of flowering plants (macrophytes). Aquatic and free-floating, their most striking qualities are a capacity for explosive reproduction and an almost complete lack of fibrous material. They are widely used for reducing chemical loading in facultative sewage lagoons, but their greatest potential lies in their ability to produce large quantities of protein rich biomass, suitable for feeding to a wide range of animals, including fish, poultry and cattle. Despite these qualities there are numerous impediments to these plants being incorporated into western farming systems. Large genetically determined variations in growth in response to nutrients and climate, apparent anti-nutritional factors, concerns about sequestration of heavy metals and possible transference of pathogens raise questions about the safety and usefulness of these plants. A clear understanding of how to address and overcome these impediments needs to be developed before duckweed is widely accepted for nutrient reclamation and as a source of animal feed.

Stressful animal housing conditions and their potential effect on sympathetic neurotransmission in mice

Although the sympathetic nervous system (SNS) plays a major role in mediating the peripheral stress response, due consideration is not usually given to the effects of prolonged stress on the SNS. The present study examined changes in neurotransmission in the SNS after exposure of mice (BALB/c) to stressful housing conditions. Focal extracellular recording of excitatory junction currents (EJCs) was used as a relative measure of neurotransmitter release from different regions of large surface areas of the mouse vas deferens. Mice were either group housed (control), isolation housed (social deprivation), group housed in a room containing rats (rat odor stress), or isolation housed in a room containing rats (concurrent stress). Social deprivation and concurrent stressors induced an increase of 30 and 335% in EJC amplitude, respectively. The success rate of recording EJCs from sets of varicosities in the concurrent stressor group was greater compared with all other groups. The present study has shown that some common animal housing conditions act as stressors and induce significant changes in sympathetic neurotransmission.

The lateral line canal sensory organs of the Epaulette Shark (Hemiscyllium ocellatum)

Examination of the lateral line canals in the Epaulette Shark reveals a much more differentiated sensory system than previously reported from any elasmobranch. Two main types of lateral line canals are found. In one type rounded patches of sensory epithelia are separated by elevations of the canal floor. The other type is a straight canal without restrictions and with an almost continuous sensory epithelium. In addition, we found epithelia (type A) with very long apical microvilli on the supporting cells. These microvilli reach beyond the stereovilli of the hair cells. Another type (B) of sensory epithelium has short microvilli on the supporting cells. In this latter type of epithelium the stereovilli of the hair cells are comparatively tall and reach out beyond the supporting cell microvilli. New hair cells are found widely in both types of sensory epithelia. These always occur as single cells, unlike those described in teleost lateral line canal sensory epithelia where new hair cells seem to form in pairs. Dying hair cells are also widespread, indicating a continuous turnover of hair cells.

Microampullary organs of a freshwater eel-tailed catfish, Plotosus (tandanus) tandanus

Whole body studies of Plotosus tandanus revealed that ampullary pores occur over the entire body of the fish, but are in higher concentrations in the head region. These pores give rise to a short canal (50-60 mum) produced by columnar epithelial cells bound together by tight junctions and desmosomes. At the junction. of the canal and the ampulla, cuboidal epithelial cells make up the wall. The ampulla consists of layers of collagen fibers that surround flattened epithelial cells in the lateral regions and give rise to supportive cells-that encase a small number of receptor cells (10-15). The ampullary wall comprises several types of cells that are adjoined via tight junctions and desmosomes between cell types. The ovoid receptor cells possess microvilli along the luminar apical area. Beneath this area, the cells are rich in mitochondria and rough endoplasmic reticulum. An unmyelinated neuron adjoins with each receptor cell opposite multiple presynaptic bodies. This form of microampulla has not been previously described within the Family Plotosidae. (C) 2002 Wiley-Liss, Inc.

Ultrastructure of the mature spermatozoa of caecilians (Amphibia : Gymnophiona)

The spermatozoa of Gymnophiona show the following autapomorphies: 1) penetration of the distal centriole by the axial fiber; 2) presence of an acrosomal baseplate; 3) presence of an acrosome seat (flattened apical end of nucleus); and 4) absence of juxta-axonemal fibers. The wide separation of the plasma membrane bounding the undulating membrane is here also considered to be apomorphic. Three plesiomorphic spermatozoal characters are recognized that are not seen in other Amphibia but occur in basal amniotes: 1) presence of mitochondria with a delicate array of concentric cristae (concentric cristae of salamander spermatozoa differ in lacking the delicate array); 2) presence of peripheral dense fibers associated with the triplets of the distal centriole; and 3) presence of a simple annulus (a highly modified, elongate annulus is present in salamander sperm). The presence of an endonuclear canal containing a perforatorium is a plesiomorphic feature of caecilian spermatozoa that is shared with urodeles, some basal anurans, sarcopterygian fish, and some amniotes. Spermatozoal synapornorphies are identified for 1) the Uraeotyphlidae and Ichthyophiidae, an 2) the Caeciliidae and Typhlonectidae, suggesting that the members of each pair of families are more closely related to each other than to other caecilians. Although caecilian spermatozoa exhibit the clear amphibian synapomorphy of the unilateral location of the undulating membrane and its axial fiber, they have no apomorphic characters that suggest a closer relationship to either the Urodela or Axiura. J. Morphol. 258:179-192, 2003. (C) 2003 Wiley-Liss, Inc.

Hemodynamic and ventilatory effects of manual respiratory physiotherapy techniques of chest clapping, vibration, and shaking in an animal model

Chest clapping, vibration, and shaking were studied in 10 physiotherapists who applied these techniques on an anesthetized animal model. Hemodynamic variables (such as heart rate, blood pressure, pulmonary artery pressure, and right atrial pressure) were measured during the application of these techniques to verify claims of adverse events. In addition, expired tidal volume and peak expiratory flow rate were measured to ascertain effects of these techniques. Physiotherapists in this study applied chest clapping at a rate of 6.2 +/- 0.9 Hz, vibration at 10.5 +/- 2.3 Hz, and shaking at 6.2 +/- 2.3 Hz. With the use of these rates, esophageal pressure swings of 8.8 +/- 5.0, 0.7 +/- 0.3, and 1.4 +/- 0.7 mmHg resulted from clapping, vibration, and shaking respectively. Variability in rates and forces generated by these techniques was 80% of variance in shaking force (P = 0.003). Application of these techniques by physiotherapists was found to have no significant effects on hemodynamic and most ventilatory variables in this study. From this study, we conclude that chest clapping, vibration, and shaking 1) can be consistently performed by physiotherapists; 2) are significantly related to physiotherapists' characteristics, particularly clinical experience; and 3) caused no significant hemodynamic effects.

Annexin II regulates multivesicular endosome biogenesis in the degradation pathway of animal cells

Proteins of the annexin family are believed to be involved in membrane-related processes, but their precise functions remain unclear. Here, we have made use of several experimental approaches, including pathological conditions, RNA interference and in vitro transport assays, to study the function of annexin II in the endocytic pathway. We find that annexin II is required for the biogenesis of multivesicular transport intermediates destined for late endosomes, by regulating budding from early endosomes-but not the membrane invagination process. Hence, the protein appears to be a necessary component of the machinery controlling endosomal membrane dynamics and multivesicular endosome biogenesis. We also find that annexin II interacts with cholesterol and that its subcellular distribution is modulated by the subcellular distribution of cholesterol, including in cells from patients with the cholesterol-storage disorder Niemann-Pick C. We conclude that annexin II forms cholesterol-containing platforms on early endosomal membranes, and that these platforms regulate the onset of the degradation pathway in animal cells.

Anatomia microscópica do canal carótico e suas relações com a cóclea e a cavidade timpânica

As relações entre as diversas estruturas nobres e vitais que se apresentam na intimidade do osso temporal constituem ainda hoje um grande desafio para o cirurgião otológico. Os estudos micro-anatômicos do mesmo se encontram entre as grandes armas na busca deste entendimento. OBJETIVO: Estudar as correlações anatômicas entre o canal carótico e a cóclea, e a ocorrência de deiscências do mesmo junto à cavidade timpânica. MATERIAL E MÉTODO: Estudo microscópico de 122 ossos temporais humanos. RESULTADOS As distâncias médias entre o canal carótico e os giros cocleares foram: no local de menor distância 1,05mm; no giro basal, 2,04mm; no giro médio, 2,32mm; e no giro apical, 5,7mm. A ocorrência de deiscências do canal carótico na cavidade timpânica foi de 35,2%. CONCLUSÃO: A pequena distância entre estruturas cocleares e o canal carótico, e a alta prevalência de deiscências do mesmo na cavidade timpânica nos relembram o desafio com o qual o cirurgião otológico se depara ao atuar sobre o osso temporal.

Síndrome de Deiscência de Canal Semicircular Superior

A Síndrome de Deiscência de Canal Semicircular Superior (SDCSS), primeiramente descrita em 1998 por Minor et al., caracteriza-se por vertigem associada à presença de nistagmo, relacionados à exposição a estímulos sonoros intensos ou a modificações de pressão dentro da orelha média ou intracraniana. Disacusia, em sua maioria de padrão condutivo à audiometria tonal, também pode estar presente. Nesta revisão da literatura objetivou-se abordar a SDCSS, com seus principais sinais e sintomas, achados diagnósticos e tratamento, assim como enfatizar a importância de sua inclusão dentre as causas de vertigem, visto tratar-se de acometimento ainda pouco conhecido até mesmo entre especialistas. O diagnóstico correto, além de possibilitar seu tratamento, impede que abordagens diagnósticas e terapêuticas inapropriadas sejam realizadas.

Determinação do sexo em catfish de canal (Ictalurus punctatus) utilizando endoscopia

A identificação precoce do sexo em peixes é um procedimento importante para o desenvolvimento de estratégias que facilitem o manejo no plantel de reprodutores. A endoscopia pode ser utilizada para essa identificação, embora em peixes seu uso ainda seja restrito. Diante disso, o objetivo deste trabalho foi validar o uso do endoscópio rígido via poro urogenital para determinação do sexo do catfish de canal (Ictalurus punctatus). O equipamento utilizado foi um endoscópio Multipurpose Rigid™ 30º com 2,7 mm de diâmetro e 18 cm de comprimento. Foram examinados 60 peixes com peso variando entre 86 e 1.032 gramas nos quais foi introduzido o endoscópio via poro genital e, logo em seguida, eutanaziados para confirmação do sexo. Amostras de tecido gonadal foram coletadas para avaliação histológica do estádio de maturação e confirmação do sexo. Os resultados mostraram que dos 60 peixes examinados, 57 tiveram confirmação positiva do sexo via endoscopia, o que corresponde a 95% da amostra. A utilização da endoscopia para determinação do sexo em I. punctatus via poro genital é viável.

A adequação do consumo de alimentos de origem animal e sua relação com renda familiar

Foi realizado estudo sobre adequação de consumo de proteínas de alto valor biológico e seu relacionamento com preço e com renda familiar, em diferentes épocas. A diminuição de consumo de origem animal observada, foi causada, por uma modificação na distribuição orçamentária, na qual, a fração destinada à aquisição de carne, leite e ovos, em 1975, foi menor do que em 1969. O ''índice de Consumo de Proteínas de Origem Animal - ICPA", avaliado através da razão entre renda familiar e custo dos alimentos de origem animal recomendados para a família, é indicador eficiente do consumo desses alimentos e indiretamente do estado nutricional. Para sua utilização é necessária a fixação de um ICPA crítico, que permita identificar as famílias quanto à capacidade econômica, uma vez que a fração destinada a compra de alimentos de origem animal varia no decorrer do tempo.

Controlo tolerante a falhas de um canal de rega

A presente dissertação pretende conceber e implementar um sistema de controlo tolerante a falhas, no canal experimental de rega da Universidade de Évora, utilizando um modelo implementado em MATLAB/SIMULINK®. Como forma de responder a este desafio, analisaram-se várias técnicas de diagnóstico de falhas, tendo-se optado por técnicas baseadas em redes neuronais para o desenvolvimento de um sistema de detecção e isolamento de falhas no canal de rega, sem ter em conta o tipo de sistema de controlo utilizado. As redes neuronais foram, assim, os processadores não lineares utilizados e mais aconselhados em situações onde exista uma abundância de dados do processo, porque aprendem por exemplos e são suportadas por teorias estatísticas e de optimização, focando não somente o processamento de sinais, como também expandindo os horizontes desse processamento. A ênfase dos modelos das redes neuronais está na sua dinâmica, na sua estabilidade e no seu comportamento. Portanto, o trabalho de investigação do qual resultou esta Dissertação teve como principais objectivos o desenvolvimento de modelos de redes neuronais que representassem da melhor forma a dinâmica do canal de rega, de modo a obter um sistema de detecção de falhas que faça uma comparação entre os valores obtidos nos modelos e no processo. Com esta diferença de valores, da qual resultará um resíduo, é possível desenvolver tanto o sistema de detecção como de isolamento de falhas baseados nas redes neuronais, possibilitando assim o desenvolvimento dum sistema de controlo tolerante a falhas, que engloba os módulos de detecção, de isolamento/diagnóstico e de reconfiguração do canal de rega. Em síntese, na Dissertação realizada desenvolveu-se um sistema que permite reconfigurar o processo em caso de ocorrência de falhas, melhorando significativamente o desempenho do canal de rega.

Evaluation of the respiratory motion effect in small animal PET images with GATE Monte Carlo simulations

The rapid growth in genetics and molecular biology combined with the development of techniques for genetically engineering small animals has led to increased interest in in vivo small animal imaging. Small animal imaging has been applied frequently to the imaging of small animals (mice and rats), which are ubiquitous in modeling human diseases and testing treatments. The use of PET in small animals allows the use of subjects as their own control, reducing the interanimal variability. This allows performing longitudinal studies on the same animal and improves the accuracy of biological models. However, small animal PET still suffers from several limitations. The amounts of radiotracers needed, limited scanner sensitivity, image resolution and image quantification issues, all could clearly benefit from additional research. Because nuclear medicine imaging deals with radioactive decay, the emission of radiation energy through photons and particles alongside with the detection of these quanta and particles in different materials make Monte Carlo method an important simulation tool in both nuclear medicine research and clinical practice. In order to optimize the quantitative use of PET in clinical practice, data- and image-processing methods are also a field of intense interest and development. The evaluation of such methods often relies on the use of simulated data and images since these offer control of the ground truth. Monte Carlo simulations are widely used for PET simulation since they take into account all the random processes involved in PET imaging, from the emission of the positron to the detection of the photons by the detectors. Simulation techniques have become an importance and indispensable complement to a wide range of problems that could not be addressed by experimental or analytical approaches.