Mechanisms of action of microbicides

This chapter describes the sites and mechanisms of action of the major groups of microbicides, relating their physical and chemical properties to interactions with microbial structures. It considers the physical, cellular and molecular methods for studying the mechanisms of action of chemical microbicides. These range from the uptake, binding and penetration of microbial cells, to the interaction with microbial structures, including the cell wall, membrane, nucleic acids, cytoplasm and enzymes. Key features of the mechanisms of action of the major groups of microbicides are described covering oxidizing agents, alkylating agents, metal ion-binding agents, nucleic acid-binding agents, protein denaturants and agents that interact with lipids. © 2013 Blackwell Publishing Ltd.

Cellular impermeability and uptake of biocides and antibiotics in Gram-positive bacteria and mycobacteria

Gram-positive bacteria possess a permeable cell wall that usually does not restrict the penetration of antimicrobials. However, resistance due to restricted penetration can occur, as illustrated by vancomycin-intermediate resistant Staphylococcus aureus strains (VISA) which produce a markedly thickened cell wall. Alterations in these strains include increased amounts of nonamidated glutamine residues in the peptidoglycan and it is suggested that the resistance mechanism involves 'affinity trapping' of vancomycin in the thickened cell wall. VISA strains have reduced doubling times, lower sensitivity to lysostaphin and reduced autolytic activity, which may reflect changes in the D-alanyl ester content of the wall and membrane teichoic acids. Mycobacterial cell walls have a high lipid content, which is assumed to act as a major barrier to the penetration of antimicrobial agents. Relatively hydrophobic antibiotics such as rifampicin and fluoroquinolones may be able to cross the cell wall by diffusion through the hydrophobic bilayer composed of long chain length mycolic acids and glycolipids. Hydrophilic antibiotics and nutrients cannot diffuse across this layer and are thought to use porin channels which have been reported in many species of mycobacteria. The occurrence of porins in a lipid bilayer supports the view that the mycobacterial wall has an outer membrane analogous to that of gram-negative bacteria. However, mycobacterial porins are much less abundant than in the gram-negative outer membrane and allow only low rates of uptake for small hydrophilic nutrients and antibiotics.

Modes of action of antibacterial agents

This chapter describes the modes of action of the major antibiotics and synthetic agents used to treat bacterial infections. Particular attention is given to the biochemical mechanisms by which the agents interfere with biosynthetic processes and the basis for their selective antibacterial action. Interference with the biosynthesis and assembly of structural components of the bacterial cell wall provides the basis for many important groups of antibiotics, including the agents targeting steps in peptidoglycan synthesis. Other agents exploit more subtle differences between bacteria and mammalian cells in fundamental processes such as DNA, RNA and protein synthesis.

Miscanthus as a feedstock for fast-pyrolysis:does agronomic treatment affect quality?

The objectives of the experiment were to assess the impact of nitrogen (N) and potassium (K) fertiliser application on the cell wall composition and fast-pyrolysis conversion quality of the commercially cultivated hybrid Miscanthus x giganteus. Five different fertiliser treatments were applied to mature Miscanthus plants which were sampled at five intervals over a growing season. The different fertiliser treatments produced significant variation in concentrations of cell wall components and ash within the biomass and affected the composition and quality of the resulting fast-pyrolysis liquids. The results indicated that application of high rates of N fertiliser had a negative effect on feedstock quality for this conversion pathway: reducing the proportion of cell wall components and increasing accumulation of ash in the harvested biomass. No exclusive effect of potassium fertiliser was observed. The low-N fertiliser treatment produced high quality, low ash-high lignin biomass most suitable as a feedstock for thermo-chemical conversion. © 2010.

Structural fruit coloration in Delarbrea michieana (Araliaceae)

The brilliant blue fruit color of Delarbrea michieana (F. Muell.) F. Muell. (Araliaceae), a Queensland understory rain forest tree, is caused by iridisomes (structures) in the epidermal cells that are produced beneath the cell wall and probably outside of the cytoplasm. Layers within these iridisomes are of such a thickness that they interfere constructively with light at 420–440 nm and produce the color. Such color production may aid in attracting mammals and large frugivorous birds (which may disperse the fruits) and may also allow ripe fruits to continue photosynthetic carbon assimilation.

Conjugated polymer nanoparticles for effective siRNA delivery to tobacco BY-2 protoplasts

Background Post transcriptional gene silencing (PTGS) is a mechanism harnessed by plant biologists to knock down gene expression. siRNAs contribute to PTGS that are synthesized from mRNAs or viral RNAs and function to guide cellular endoribonucleases to target mRNAs for degradation. Plant biologists have employed electroporation to deliver artificial siRNAs to plant protoplasts to study gene expression mechanisms at the single cell level. One drawback of electroporation is the extensive loss of viable protoplasts that occurs as a result of the transfection technology. Results We employed fluorescent conjugated polymer nanoparticles (CPNs) to deliver siRNAs and knockdown a target gene in plant protoplasts. CPNs are non toxic to protoplasts, having little impact on viability over a 72 h period. Microscopy and flow cytometry reveal that CPNs can penetrate protoplasts within 2 h of delivery. Cellular uptake of CPNs/siRNA complexes were easily monitored using epifluorescence microscopy. We also demonstrate that CPNs can deliver siRNAs targeting specific genes in the cellulose biosynthesis pathway (NtCesA-1a and NtCesA-1b). Conclusions While prior work showed that NtCesA-1 is a factor involved in cell wall synthesis in whole plants, we demonstrate that the same gene plays an essential role in cell wall regeneration in isolated protoplasts. Cell wall biosynthesis is central to cell elongation, plant growth and development. The experiments presented here shows that NtCesA is also a factor in cell viability. We show that CPNs are valuable vehicles for delivering siRNAs to plant protoplasts to study vital cellular pathways at the single cell level.

Medical mycology and fungal immunology : new research perspectives addressing a major world health challenge

Peer reviewed

Pathogen-Specific Adaptations to Conserved Signaling Pathways in Cryptococcus neoformans

Cryptococcus neoformans is an opportunistic fungal pathogen that causes significant disease worldwide. Even though this fungus has not evolved specifically to cause human disease, it has a remarkable ability to adapt to many different environments within its infected host. C. neoformans adapts by utilizing conserved eukaryotic and fungal-specific signaling pathways to sense and respond to stresses within the host. Upon infection, two of the most significant environmental changes this organism experiences are elevated temperature and high pH.

Conserved Rho and Ras family GTPases are central regulators of thermotolerance in C. neoformans. Many GTPases require prenylation to associate with cellular membranes and function properly. Using molecular genetic techniques, microscopy, and infection models, I demonstrated that the prenyltransferase, geranylgeranyl transferase I (GGTase I) is required for thermotolerance and pathogenesis. Using fluorescence microscopy, I found that only a subset of conserved GGTase I substrates requires this enzyme for membrane localization. Therefore, the C. neoformans GGTase I may recognize its substrate in a slightly different manner than other eukaryotic organisms.

The alkaline response transcription factor, Rim101, is a central regulator of stress-response genes important for adapting to the host environment. In particular, Rim101 regulates cell surface alterations involved in immune avoidance. In other fungi, Rim101 is activated by alkaline pH through a conserved signaling pathway, but this pathway had yet been characterized in C. neoformans. Using molecular genetic techniques, I identified and analyzed the conserved members of the Rim pathway. I found that it was only partially conserved in C. neoformans, missing the components that sense pH and initiate pathway activation. Using a genetic screen, I identified a novel Rim pathway component named Rra1. Structural prediction and genetic epistasis experiments suggest that Rra1 may serve as the Rim pathway pH sensor in C. neoformans and other related basidiomycete fungi.

To explore the relevance of Rim pathway signaling in the interaction of C neoformans with its host, I characterized the Rim101-regulated cell wall changes that prevent immune detection. Using HPLC, enzymatic degradation, and cell wall stains, I found that the rim101Δ mutation resulted in increased cell wall chitin exposure. In vitro co-culture assays demonstrated that increased chitin exposure is associated with enhanced activation of macrophages and dendritic cells. To further test this association, I demonstrated that other mutant strains with increased chitin exposure induce macrophage and dendritic cell responses similar to rim101Δ. We used primary macrophages from mutant mouse lines to demonstrate that members of both the Toll-like receptor and C-type lectin receptor families are involved in detecting strains with increased chitin exposure. Finally, in vivo immunological experiments demonstrated that the rim101Δ strain induced a global inflammatory immune response in infected mouse lungs, expanding upon our previous in vivo rim101Δ studies. These results demonstrate that cell wall organization largely determines how fungal cells are detected by the immune system.

Algal Calcification and Silicification

The algae represent major producers of calcium carbonate and silica among the world's biota. Calcification involves the precipitation of CaCO3 from Ca2+ and CO32− ions. Algal calcification by coccolithophores may account for up to half of global oceanic CaCO3 production. Silicification, the transformation of silicic acid into skeletal material, occurs in a few algal groups. The abundant diatoms represent the major silicifiers, playing a key role in marine silica cycling. Fossilised diatomaceous deposits have long been exploited for building and filling materials. Biomineralisation of calcium and silicon require homeostatic ion controls that are well characterised for Ca2+ and H+ in coccolithophores. Calcification occurs in an alkalinised vesicle, while silicification requires an acidic pH. Research on silicification remains focused upon cell wall development. Initiation and development of structures that are mineralised intracellularly requires initiation and regulation by organic components within the vesicles. Low-temperature, low-pressure biogenic formation of silica and calcite has potential for biotechnological application in novel industrial processes.

Algal Calcification and Silicification

The algae represent major producers of calcium carbonate and silica among the world's biota. Calcification involves the precipitation of CaCO3 from Ca2+ and CO32− ions. Algal calcification by coccolithophores may account for up to half of global oceanic CaCO3 production. Silicification, the transformation of silicic acid into skeletal material, occurs in a few algal groups. The abundant diatoms represent the major silicifiers, playing a key role in marine silica cycling. Fossilised diatomaceous deposits have long been exploited for building and filling materials. Biomineralisation of calcium and silicon require homeostatic ion controls that are well characterised for Ca2+ and H+ in coccolithophores. Calcification occurs in an alkalinised vesicle, while silicification requires an acidic pH. Research on silicification remains focused upon cell wall development. Initiation and development of structures that are mineralised intracellularly requires initiation and regulation by organic components within the vesicles. Low-temperature, low-pressure biogenic formation of silica and calcite has potential for biotechnological application in novel industrial processes.

Structure and lipid interactions of membrane-associated glycosyltransferases : Cationic patches and anionic lipids regulate biomembrane binding of both GT-A and GT-B enzymes

This thesis concerns work on structure and membrane interactions of enzymes involved in lipid synthesis, biomembrane and cell wall regulation and cell defense processes. These proteins, known as glycosyltransferases (GTs), are involved in the transfer of sugar moieties from nucleotide sugars to lipids or chitin polymers. Glycosyltransferases from three types of organisms have been investigated; one is responsible for vital lipid synthesis in Arabidopsis thaliana (atDGD2) and adjusts the lipid content in biomembranes if the plant experiences stressful growth conditions. This enzyme shares many structural features with another GT found in gram-negative bacteria (WaaG). WaaG is however continuously active and involved in synthesis of the protective lipopolysaccharide layer in the cell walls of Escherichia coli. The third type of enzymes investigated here are chitin synthases (ChS) coupled to filamentous growth in the oomycete Saprolegnia monoica. I have investigated two ChS-derived MIT domains that may be involved in membrane interactions within the endosomal pathway. From analysis of the three-dimensional structure and the amino-acid sequence, some important regions of these very large proteins were selected for in vitro studies. By the use of an array of biophysical methods (e.g. Nuclear Magnetic Resonance, Fluorescence and Circular Dichroism spectroscopy) and directed sequence analyses it was possible to shed light on some important details regarding the structure and membrane-interacting properties of the GTs. The importance of basic amino-acid residues and hydrophobic anchoring segments, both generally and for the abovementioned proteins specifically, is discussed. Also, the topology and amino-acid sequence of GT-B enzymes of the GT4 family are analyzed with emphasis on their biomembrane association modes. The results presented herein regarding the structural and lipid-interacting properties of GTs aid in the general understanding of glycosyltransferase activity. Since GTs are involved in a high number of biochemical processes in vivo it is of outmost importance to understand the underlying processes responsible for their activity, structure and interaction events. The results are likely to be useful for many applications and future experimental design within life sciences and biomedicine.

Development of Imaging Mass Spectrometry Analysis of Lipids in Biological and Clinically Relevant Applications

La spectrométrie de masse mesure la masse des ions selon leur rapport masse sur charge. Cette technique est employée dans plusieurs domaines et peut analyser des mélanges complexes. L’imagerie par spectrométrie de masse (Imaging Mass Spectrometry en anglais, IMS), une branche de la spectrométrie de masse, permet l’analyse des ions sur une surface, tout en conservant l’organisation spatiale des ions détectés. Jusqu’à présent, les échantillons les plus étudiés en IMS sont des sections tissulaires végétales ou animales. Parmi les molécules couramment analysées par l’IMS, les lipides ont suscité beaucoup d'intérêt. Les lipides sont impliqués dans les maladies et le fonctionnement normal des cellules; ils forment la membrane cellulaire et ont plusieurs rôles, comme celui de réguler des événements cellulaires. Considérant l’implication des lipides dans la biologie et la capacité du MALDI IMS à les analyser, nous avons développé des stratégies analytiques pour la manipulation des échantillons et l’analyse de larges ensembles de données lipidiques. La dégradation des lipides est très importante dans l’industrie alimentaire. De la même façon, les lipides des sections tissulaires risquent de se dégrader. Leurs produits de dégradation peuvent donc introduire des artefacts dans l’analyse IMS ainsi que la perte d’espèces lipidiques pouvant nuire à la précision des mesures d’abondance. Puisque les lipides oxydés sont aussi des médiateurs importants dans le développement de plusieurs maladies, leur réelle préservation devient donc critique. Dans les études multi-institutionnelles où les échantillons sont souvent transportés d’un emplacement à l’autre, des protocoles adaptés et validés, et des mesures de dégradation sont nécessaires. Nos principaux résultats sont les suivants : un accroissement en fonction du temps des phospholipides oxydés et des lysophospholipides dans des conditions ambiantes, une diminution de la présence des lipides ayant des acides gras insaturés et un effet inhibitoire sur ses phénomènes de la conservation des sections au froid sous N2. A température et atmosphère ambiantes, les phospholipides sont oxydés sur une échelle de temps typique d’une préparation IMS normale (~30 minutes). Les phospholipides sont aussi décomposés en lysophospholipides sur une échelle de temps de plusieurs jours. La validation d’une méthode de manipulation d’échantillon est d’autant plus importante lorsqu’il s’agit d’analyser un plus grand nombre d’échantillons. L’athérosclérose est une maladie cardiovasculaire induite par l’accumulation de matériel cellulaire sur la paroi artérielle. Puisque l’athérosclérose est un phénomène en trois dimension (3D), l'IMS 3D en série devient donc utile, d'une part, car elle a la capacité à localiser les molécules sur la longueur totale d’une plaque athéromateuse et, d'autre part, car elle peut identifier des mécanismes moléculaires du développement ou de la rupture des plaques. l'IMS 3D en série fait face à certains défis spécifiques, dont beaucoup se rapportent simplement à la reconstruction en 3D et à l’interprétation de la reconstruction moléculaire en temps réel. En tenant compte de ces objectifs et en utilisant l’IMS des lipides pour l’étude des plaques d’athérosclérose d’une carotide humaine et d’un modèle murin d’athérosclérose, nous avons élaboré des méthodes «open-source» pour la reconstruction des données de l’IMS en 3D. Notre méthodologie fournit un moyen d’obtenir des visualisations de haute qualité et démontre une stratégie pour l’interprétation rapide des données de l’IMS 3D par la segmentation multivariée. L’analyse d’aortes d’un modèle murin a été le point de départ pour le développement des méthodes car ce sont des échantillons mieux contrôlés. En corrélant les données acquises en mode d’ionisation positive et négative, l’IMS en 3D a permis de démontrer une accumulation des phospholipides dans les sinus aortiques. De plus, l’IMS par AgLDI a mis en évidence une localisation différentielle des acides gras libres, du cholestérol, des esters du cholestérol et des triglycérides. La segmentation multivariée des signaux lipidiques suite à l’analyse par IMS d’une carotide humaine démontre une histologie moléculaire corrélée avec le degré de sténose de l’artère. Ces recherches aident à mieux comprendre la complexité biologique de l’athérosclérose et peuvent possiblement prédire le développement de certains cas cliniques. La métastase au foie du cancer colorectal (Colorectal cancer liver metastasis en anglais, CRCLM) est la maladie métastatique du cancer colorectal primaire, un des cancers le plus fréquent au monde. L’évaluation et le pronostic des tumeurs CRCLM sont effectués avec l’histopathologie avec une marge d’erreur. Nous avons utilisé l’IMS des lipides pour identifier les compartiments histologiques du CRCLM et extraire leurs signatures lipidiques. En exploitant ces signatures moléculaires, nous avons pu déterminer un score histopathologique quantitatif et objectif et qui corrèle avec le pronostic. De plus, par la dissection des signatures lipidiques, nous avons identifié des espèces lipidiques individuelles qui sont discriminants des différentes histologies du CRCLM et qui peuvent potentiellement être utilisées comme des biomarqueurs pour la détermination de la réponse à la thérapie. Plus spécifiquement, nous avons trouvé une série de plasmalogènes et sphingolipides qui permettent de distinguer deux différents types de nécrose (infarct-like necrosis et usual necrosis en anglais, ILN et UN, respectivement). L’ILN est associé avec la réponse aux traitements chimiothérapiques, alors que l’UN est associé au fonctionnement normal de la tumeur.

Computer simulations of soft particles in flow

Understanding the dynamics of blood cells is a crucial element to discover biological mechanisms, to develop new efficient drugs, design sophisticated microfluidic devices, for diagnostics. In this work, we focus on the dynamics of red blood cells in microvascular flow. Microvascular blood flow resistance has a strong impact on cardiovascular function and tissue perfusion. The flow resistance in microcirculation is governed by flow behavior of blood through a complex network of vessels, where the distribution of red blood cells across vessel cross-sections may be significantly distorted at vessel bifurcations and junctions. We investigate the development of blood flow and its resistance starting from a dispersed configuration of red blood cells in simulations for different hematocrits, flow rates, vessel diameters, and aggregation interactions between red blood cells. Initially dispersed red blood cells migrate toward the vessel center leading to the formation of a cell-free layer near the wall and to a decrease of the flow resistance. The development of cell-free layer appears to be nearly universal when scaled with a characteristic shear rate of the flow, which allows an estimation of the length of a vessel required for full flow development, $l_c \approx 25D$, with vessel diameter $D$. Thus, the potential effect of red blood cell dispersion at vessel bifurcations and junctions on the flow resistance may be significant in vessels which are shorter or comparable to the length $l_c$. The presence of aggregation interactions between red blood cells lead in general to a reduction of blood flow resistance. The development of the cell-free layer thickness looks similar for both cases with and without aggregation interactions. Although, attractive interactions result in a larger cell-free layer plateau values. However, because the aggregation forces are short-ranged at high enough shear rates ($\bar{\dot{\gamma}} \gtrsim 50~\text{s}^{-1}$) aggregation of red blood cells does not bring a significant change to the blood flow properties. Also, we develop a simple theoretical model which is able to describe the converged cell-free-layer thickness with respect to flow rate assuming steady-state flow. The model is based on the balance between a lift force on red blood cells due to cell-wall hydrodynamic interactions and shear-induced effective pressure due to cell-cell interactions in flow. We expect that these results can also be used to better understand the flow behavior of other suspensions of deformable particles such as vesicles, capsules, and cells. Finally, we investigate segregation phenomena in blood as a two-component suspension under Poiseuille flow, consisting of red blood cells and target cells. The spatial distribution of particles in blood flow is very important. For example, in case of nanoparticle drug delivery, the particles need to come closer to microvessel walls, in order to adhere and bring the drug to a target position within the microvasculature. Here we consider that segregation can be described as a competition between shear-induced diffusion and the lift force that pushes every soft particle in a flow away from the wall. In order to investigate the segregation, on one hand, we have 2D DPD simulations of red blood cells and target cell of different sizes, on the other hand the Fokker-Planck equation for steady state. For the equation we measure force profile, particle distribution and diffusion constant across the channel. We compare simulation results with those from the Fokker-Planck equation and find a very good correspondence between the two approaches. Moreover, we investigate the diffusion behavior of target particles for different hematocrit values and shear rates. Our simulation results indicate that diffusion constant increases with increasing hematocrit and depends linearly on shear rate. The third part of the study describes development of a simulation model of complex vascular geometries. The development of the model is important to reproduce vascular systems of small pieces of tissues which might be gotten from MRI or microscope images. The simulation model of the complex vascular systems might be divided into three parts: modeling the geometry, developing in- and outflow boundary conditions, and simulation domain decomposition for an efficient computation. We have found that for the in- and outflow boundary conditions it is better to use the SDPD fluid than DPD one because of the density fluctuations along the channel of the latter. During the flow in a straight channel, it is difficult to control the density of the DPD fluid. However, the SDPD fluid has not that shortcoming even in more complex channels with many branches and in- and outflows because the force acting on particles is calculated also depending on the local density of the fluid.

Effets des procédés d’usinage de finition sur les propriétés de surface, la performance d’un vernis et l’émission de poussières du bois de chêne rouge

La performance d’un produit de finition sur le bois est influencée par la manière dont la surface est préparée. Le ponçage est très utilisé pour préparer les surfaces lors de la finition. Toutefois, ce procédé génère une grande quantité de poussières. Ainsi, les effets des procédés d’usinage sur les propriétés de surface, la performance d’un vernis et l’émission de poussières ont été étudiés dans le but de déterminer les modes de préparation des surfaces les plus adéquats pour le bois de chêne rouge. Dans un premier volet, les propriétés de surface et la performance d’un vernis ont été évaluées sur les surfaces préparées à l’aide du procédé traditionnel de ponçage et de trois procédés alternatifs de rabotage soit la coupe périphérique droite, la coupe hélicoïdale et la coupe oblique. La qualité de surface a été évaluée au moyen des caractéristiques de rugosité, d’endommagement cellulaire et de mouillabilité. Des essais de résistance à l’adhésion d’un vernis d’usage intérieur ont été effectués avant et après un traitement de vieillissement accéléré. Les résultats ont montré que le ponçage a induit une rugosité et un niveau de fibrillation supérieurs à ceux des autres procédés, ainsi qu’une mouillabilité et une adhésion du vernis après vieillissement accéléré élevées. Les surfaces rabotées avec la coupe périphérique droite ont présenté un certain niveau de fibrillation, une rugosité et une mouillabilité intermédiaires. Néanmoins, l’adhésion du vernis après vieillissement a été également inférieure par rapport aux autres procédés. La coupe hélicoïdale a produit une rugosité intermédiaire. D’autre part, la coupe oblique a été le procédé qui a présenté une perte d’adhésion après vieillissement similaire au ponçage. Ce procédé a généré des surfaces lisses avec rugosité et mouillabilité intermédiaires. Sur la base des résultats obtenus, le ponçage à l’aide d’un programme P100-grain et une vitesse d’avance de 7 m/min, la coupe périphérique droite avec un angle d’attaque de 25° et une onde d’usinage de 1,0 mm, la coupe hélicoïdale avec une onde d’usinage de 1,0 mm et la coupe oblique realisé avec un angle oblique de 15° ont permis d’obtenir les meilleures conditions d’usinage pour chaque procédé. Dans un deuxième volet, l’effet de différents paramètres de coupe sur l’émission de poussières et la rugosité de la surface a été étudié lors de la coupe hélicoïdale. Les émissions de poussières ont diminué avec la diminution de laprofondeur de coupe et l’augmentation de l’épaisseur moyenne du copeau. Cependant, les surfaces obtenues avec l’épaisseur moyenne du copeau plus élevée ont présenté une rugosité supérieure. Par contre, si une surface plus lisse est requise, une vitesse d’avance intermédiaire doit être utilisée afin de diminuer la rugosité des surfaces sans exposer les travailleurs à des niveaux élevés de poussière de bois. Par ailleurs, l’émission de poussières pour chaque fraction de particules peut être estimée à travers les modèles développés.

Whipple’s disease infection surgical treatment: presentation of a rare case and literature review

The Whipple’ Disease (W.D.) is a very rare disease with an incidence of 1 per 1.000.000 inhabitants; it is a systemic infection that may mimic a wide spectrum of clinical disorders, which may have a fatal outcome and affects mainly male 40-50 years old. The infective agent is an actinomycete, Tropheryma Whipplei (T.W.) that was isolated 100 years after first description by Wipple, and identified in macrophages of mucosa of the small intestine by biopsy which is characterized by periodic acid-Schiff-positive, products of the inner membrane of his polysaccharide bacterial cell wall. The multisystemic clinical manifestations evolve rapidly towards an organic decay characterized by weight loss, malabsorption, diarrhea, polyathralgia, opthalmoplegia, neuro-psychiatric disorders and sometimes associated to endocarditis. Early antibiotic treatment with trimethoprim and sulfometathaxazole reduces the fatal evolution of the disease. The authors present a rare experience about a female subject in which the clinical gastrointestinal signs were preceded by neuro-psychiatric disorders, and evolved into obstruction and intestinal perforation which required an emergency surgery with temporary ileostomy, recanalized only after adequate medical treatment with a full dose of antibiotic and resolution of clinical disease for the high risks of fistulae for the edema and lymphadenopathy of mucosa. The diagnosis was histologically examined by intestinal biopsy performed during surgery, which showed PAS-positive histiocytes, while PRC polymerase RNA was negative, which confirms the high sensibility of PAS positive and low specificity of RNA polymerase for T.W.