Academic literature on the topic 'Glanders, transmission'

Glanders is a fatal bacterial infection of equids caused by Burkholderia mallei. The infection can be transmitted to humans through prolonged direct contact with glanderous equids. Recently, reemergence of equine glanders has been reported in many countries. To investigate zoonotic transmission of B mallei infection, sera were collected from 538 humans including equine handlers and veterinary professionals exposed to glanderous equids. Samples were tested by ELISA (enzyme-linked immunosorbent assay) and complement fixation test and found negative for B mallei–specific antibodies. Even though there was no incidence of human glanders during this survey period, occupational exposure will continue to remain a serious concern and a key risk factor. Therefore, we emphasize the need for intersectoral collaboration and coordination among veterinary, human, and public health authorities for continuous surveillance and monitoring of human glanders under one health concept.

Increasing antimicrobial resistance due to misuse and overuse of antimicrobials, as well as a lack of new and innovative antibiotics in development has become an alarming global threat. Preventative therapeutics, like vaccines, are combative measures that aim to stop infections at the source, thereby decreasing the overall use of antibiotics. Infections due to Gram-negative pathogens pose a significant treatment challenge because of substantial multidrug resistance that is acquired and spread throughout the bacterial population. Burkholderia spp. are Gram-negative intrinsically resistant bacteria that are responsible for environmental and nosocomial infections. The Burkholderia cepacia complex are respiratory pathogens that primarily infect immunocompromised and cystic fibrosis patients, and are acquired through contaminated products and equipment, or via patient-to-patient transmission. The Burkholderia pseudomallei complex causes percutaneous wound, cardiovascular, and respiratory infections. Transmission occurs through direct exposure to contaminated water, water-vapors, or soil, leading to the human disease melioidosis, or the equine disease glanders. Currently there is no licensed vaccine against any Burkholderia pathogen. This review will discuss Burkholderia vaccine candidates derived from outer membrane proteins, OmpA, OmpW, Omp85, and Bucl8, encompassing their structures, conservation, and vaccine formulation.

ABSTRACT Infectivity of Anaplasma spp. develops when infected ticks feed on a mammalian host (transmission feed). Specific Anaplasma marginale major surface protein 2 (MSP2) variants are selected for within the tick and are expressed within the salivary glands. The aims of this study were to determine when and where MSP2 variant selection occurs in the tick, how MSP2 expression is regulated in salivary glands of transmission-feeding ticks, and whether the number of A. marginale organisms per salivary gland is significantly increased during transmission feeding. The South Idaho strain of A. marginale was used, as MSP2 expression is restricted to two variants, SGV1 and SGV2, in Dermacentor andersoni. Using Western blot, real-time PCR, and DNA sequencing analyses it was shown that restriction and expression of MSP2 occurs early in the midgut within the first 48 h of the blood meal, when ticks acquire infection. A. marginale is present in the tick salivary glands before transmission feeding is initiated, but the msp2 mRNA and MSP2 protein levels per A. marginale organism increase only minimally and transiently in salivary glands of transmission-feeding ticks compared to that of unfed ticks. A. marginale numbers per tick increase gradually in salivary glands of both transmission-fed and unfed ticks. It is concluded that MSP2 variant selection is an early event in the tick and that MSP2 variants SGV1 and SGV2 are expressed both in the midgut and salivary glands. While MSP2 may be required for infectivity, there is no strict temporal correlation between MSP2 expression and the development of infectivity.

Zika virus (ZIKV) belongs to the large category of arboviruses. Surprisingly, several human-to-human transmissions of ZIKV have been notified, either following sexual intercourse or from the mother to fetus during pregnancy. Importantly, high viral loads have been detected in the human breast milk of infected mothers, and the existence of breastfeeding as a new mode of mother-to-child transmission of ZIKV was recently hypothesized. However, the maternal origin of infectious particles in breast milk is currently unknown. Here, we show that ZIKV disseminates to the mammary glands of infected mice after both systemic and local exposure with differential kinetics. Ex vivo, we demonstrate that primary human mammary epithelial cells were sensitive and permissive to ZIKV infection in this study. Moreover, by using in vitro models, we prove that mammary luminal- and myoepithelial-phenotype cell lines are both able to produce important virus progeny after ZIKV exposure. Our data suggest that the dissemination of ZIKV to the mammary glands and subsequent infection of the mammary epithelium could be one mechanism of viral excretion in human breast milk.

ABSTRACT Understanding the determinants of efficient tick-borne microbial transmission is needed to better predict the emergence of highly transmissible pathogen strains and disease outbreaks. Although the basic developmental cycle of Anaplasma and Ehrlichia spp. within the tick has been delineated, there are marked differences in the ability of specific strains to be efficiently tick transmitted. Using the highly transmissible St. Maries strain of Anaplasma marginale in Dermacentor andersoni as a positive control and two unrelated nontransmissible strains, we identified distinct barriers to efficient transmission within the tick. The Mississippi strain was unable to establish infection at the level of the midgut epithelium despite successful ingestion of infected blood following acquisition feeding on a bacteremic animal host. This inability to colonize the midgut epithelium prevented subsequent development within the salivary glands and transmission. In contrast, A. marginale subsp. centrale colonized the midgut and then the salivary glands, replicating to a titer indistinguishable from that of the highly transmissible St. Maries strain and at least 100 times greater than that previously associated with successful transmission. Nonetheless, A. marginale subsp. centrale was not transmitted, even when a large number of infected ticks was used for transmission feeding. These results establish that there are at least two specific barriers to efficient tick-borne transmission, the midgut and salivary glands, and highlight the complexity of the pathogen-tick interaction.

The objective of the present study was to evaluate the glands of wall of congenital fistulae of the lower lip with the transmission electron microscope in order to characterize their microstructural pattern. Thin section of Araldite resin embedded congenital fistulae of the lower lip of four patients with Van der Woude syndrome from the Hospital de Reabilitação de Anomalias Craniofaciais da Universidade de São Paulo, Bauru, SP, were analyzed with a transmission electron microscope. The results showed that the glands were mostly made by typical mucous acini exhibiting, with certain frequency, myoepithelial cells surrounding them. In some of lobules, a few acini smaller than the typical mucous, showed granules of moderate electron density or containing a dense core or exhibiting small dense spherule and predominance granular material. These granules resemble to described recently by others in various human minor salivary glands. We concluded that glands associated with congenital fistula of lower lip of patients with Van der Woude syndrome, in spite of being located in vermilion border of the lip, showed at the transmission electron microscope characteristics of labial minor salivary gland, i.e, are mostly mucous with a few seromucous units, while typical seromucous demilunes are not present.

ABSTRACT The malaria parasite sporozoite transmission stage develops and differentiates within parasite oocysts on the Anopheles mosquito midgut. Successful inoculation of the parasite into a mammalian host is critically dependent on the sporozoite's ability to first infect the mosquito salivary glands. Remarkable changes in tissue infection competence are observed as the sporozoites transit from the midgut oocysts to the salivary glands. Our microarray analysis shows that compared to oocyst sporozoites, salivary gland sporozoites upregulate expression of at least 124 unique genes. Conversely, oocyst sporozoites show upregulation of at least 47 genes (upregulated in oocyst sporozoites [UOS genes]) before they infect the salivary glands. Targeted gene deletion of UOS3, encoding a putative transmembrane protein with a thrombospondin repeat that localizes to the sporozoite secretory organelles, rendered oocyst sporozoites unable to infect the mosquito salivary glands but maintained the parasites' liver infection competence. This phenotype demonstrates the significance of differential UOS expression. Thus, the UIS-UOS gene classification provides a framework to elucidate the infectivity and transmission success of Plasmodium sporozoites on a whole-genome scale. Genes identified herein might represent targets for vector-based transmission blocking strategies (UOS genes), as well as strategies that prevent mammalian host infection (UIS genes).

Aujourd'hui, l'émergence ou la réémergence de maladies transmises par les tiques (TBDs) devient un problème majeur. En raison des problèmes générés par l'utilisation des acaricides (pollution, résistance), il est donc urgent d'identifier de nouvelles approches pour contrôler les populations de tiques. Parmi ces stratégies, la vaccination visant des molécules conservées chez les tiques et impliquées dans leur capacité vectorielle, sont devenues particulièrement attractives. En conséquence, l'identification de cibles antigéniques appropriées est un défi majeur pour la mise en œuvre de ces stratégies de contrôle des tiques et des TBDs. Dans le présent travail, l'objectif principal est d'élucider les interactions moléculaires entre I. ricinus et B. henselae, afin d'identifier des molécules qui pourraient représenter des cibles vaccinales contre les tiques et les agents pathogènes qu'elles transmettent. Dans ce but, nous avons identifié, par séquençage à haut débit, des transcrits d'Ixodes ricinus différentiellement exprimés au niveau des glandes salivaires de la tique en réponse à une infection par B. henselae. Dans un second temps, l'implication d'un de ces transcrits surexprimés lors de l'infection dans la transmission de B. henselae, a été évaluée. Enfin, et en premier lieu, nous avons validé l'utilisation de la technique de gorgement artificiel sur membrane pour infecter I. ricinus par B. henselae et évalué l'impact de différents paramètres sur le gorgement des tiques. Les résultats ont montré que la technique de gorgement sur membrane est bien adaptée à l'infection d'I. ricinus par B. henselae en laboratoire, et que la proportion et le poids des tiques gorgées sont diminués lors de l'infection du sang par la bactérie Le séquençage en 454 des glandes salivaires de tiques a généré une banque de référence contenant 24, 539 transcrits, et la comparaison des glandes salivaires d'I. ricinus infectés et non-infectés par B. henselae a montré que 839 et 517 transcrits étaient respectivement significativement surexprimés et sous-exprimés en réponse à l'infection par des bactéries. Parmi les gènes de fonction connue, 161 transcrits correspondent à 9 familles déjà identifiées, quand les autres correspondent à des gènes de fonction inconnue. L'extinction par RNA interférence du gène le plus surexprimé, IrSPI qui appartient à la famille des inhibiteurs de sérine protéase BPTI/Kunitz, a entraîné une réduction de la taille du repas sanguin prit par les tiques (et donc sa descendance) ainsi que du niveau d'infection au niveau des glandes salivaires. En conclusion, cette étude a démontré que la technique de gorgement artificiel des tiques sur membrane est un outil puissant pour étudier les interactions entre les tiques et les agents pathogènes qu'elles transmettent comme B. henselae. Ce travail apporte aussi une nette avancée en termes de données génétiques sur I. ricinus (dont le génome n'est pas séquencé) et sur les interactions moléculaires entre une bactérie et son vecteur. Enfin, ce travail a permis la mise en évidence d'une molécule représentant un candidat vaccinal très prometteur à la fois pour diminuer la population de tiques et lutter contre les agents pathogènes qu'elles transmettent. Dans le futur, et en fonction de la confirmation du rôle des gènes identifiés ici dans la transmission bactérienne, de nombreux candidats vaccins pourront ainsi être évalués, ouvrant alors de nouvelles perspectives dans la lutte contre les tiques et les maladies dues aux agents qu'elles transmettent
Ticks are obligate blood-feeding ectoparasites of many hosts including mammals, birds and reptiles. After mosquitoes, they are the most important vectors worldwide, and are able to transmit the highest variety of pathogens including virus, bacteria and parasites. Ixodes ricinus (Acari: Ixodidae), the most common tick species in Europe, is a three-life stage hard tick. It is frequently associated with bites in humans, and transmits several pathogens, including Tick-Borne Encephalitis, Babesia spp., Borrellia spp., Anaplasma spp., and to a lesser extent Bartonella spp. Bartonella spp. are facultative intracellular bacteria associated with a number of emerging diseases in humans and animals. It has been demonstrated that I. ricinus is a competent vector for B. henselae that causes cat scratch disease as well as being increasingly associated with a number of other syndromes, particularly ocular infections and endocarditis. Recently, emergence or re-emergence of tick-borne diseases (TBDs) is increasingly becoming a problem. Indeed, and because of the limited success and disadvantages of controlling TBDs via acaricides, new approaches are urgently needed. Therefore, vaccine strategies that target conserved components of ticks that play roles in vector infestation and vector capacity have become particularly attractive. Accordingly, the identification of suitable antigenic targets is a major challenge for the implementation of tick and TBDs control strategies. In the present work, the main objective is to elucidate molecular interactions between I. ricinus and B. henselae in order to identify some targets that may be used as vaccines against ticks and tick-borne pathogens. Two principal points are focused on: primarily, to identify I. ricinus salivary gland differentially expressed transcripts in response to B. henselae infection with next generation sequencing techniques (454 pyrosequencing and HiSeq 2000); secondly, to validate the implication of one of these transcripts in the transmission of B. henselae. For that purpose, and at first, we validated artificial membrane feeding technique for ticks infection by B. henselae and evaluated the impact of several parameters on tick feeding. Results showed that membrane feeding technique is a suitable method to infect I. ricinus with B. henselae and that the proportion and weight of engorged ticks are decreased by B. henselae infection of the blood meal. Transcriptional analysis of the tick salivary glands generated a reference databank containing 24,539 transcripts, and the comparison of B. henselae-infected and non-infected I. ricinus female salivary glands showed that 839 and 517 transcripts were significantly up- and down-regulated in response to bacteria infection, respectively. Among them, 161 transcripts corresponded to 9 groups of ticks salivary gland gene families already described, when the other ones corresponded to genes of unknown function. Silencing the most up-regulated gene IrSPI, which belongs to BPTI/Kunitz family of serine protease inhibitor, resulted in reduction of tick feeding and bacteria load in tick salivary gland. In conclusion, this work demonstrated that artificial-membrane feeding technique is a powerful tool for investigating the interactions between tick and tick-borne pathogens as B. henselae. It also increases the available genomic information for I. ricinus and the knowledge to improve our understanding of the molecular interaction between tick and tick-borne pathogens. At last, it provides a potential vaccine candidate to control tick-borne diseases. In the future, and depending of differentially expressed genes' role confirmation, more and more vaccine candidate will be provided by this work, and the strategy of controlling tick and tick-borne disease will come to a new stage

L'ensemble de ce travail s'inscrit dans le cadre de l'étude de la neurotransmission adéno-sinergique au niveau central, en privilégiant une structure, la glande pinéale, impliquée soit dans la physiologie de la reproduction, soit dans la pathologie neurologique et psychiatrique selon qu'il s'agisse de l'animal ou de l'Homme. L'adénosine régule, en effet, l'activité neuronale dans plusieurs région cérébrales et ainsi la transmission synaptique dont l'une des principales conséquentes est une affectation du comportement. L'une des principales découvertes, pour une meilleure compréhension du rôle de l'adénosine dans le système nerveux central, a été la caractérisation de récepteurs membranaires spécifiques. Par contre, rien n'était connu au niveau de la glande pinéale. Nous avons mis en évidence, pour la première fois, l'existence de récepteurs à l'adénosine de type A2 sur les membranes des pinéalocytes de rat et montré que ces récepteurs sont fonctionnels, couplés positivement à l'adénylate cyclase et qu'ils participent, in vivo et in vitro, à la synthèse et à la libération de la mélatonine. Cette hormone, marqueur de la glande pinéale, est formée après stimulation par l'adénosine et des agonistes spécifiques A2. La noradrénaline, un agoniste alpha 1 et béta-adrénergique potentialise leurs effets, résultat qui suggère une interaction entre les différents mécanismes de transduction impliquant soit le système adénylate cyclasique soit les phosphoinositides. Nous avons confirmé la présence de récepteurs A2 dans la glande pinéale de l'homme sain et nous avons montré une modification de leurs paramètres cinétiques chez le suicidé. Enfin, nous avons observé que divers paramètres tant physiologiques (âge, indice de méthylation) qu'environnementaux (lumière continue) peuvent moduler cette neurotransmission adénosinergique au niveau central et/ou au niveau de la glande pinéale
[This work takes place in the study of the central adenosine neurotransmitter system, improving a structure, the pineal gland, involved either in the physiology of reproduction in mammals or in the physiopathology of the central nervous system in human. It is known that adenosine and adenosine analogues regulate the neuronal activity in several brain areas and, thus, the synaptic transmission, and they have been shown to be highly active at the cellular level in altering neuronal activity and in affective behaviour as well. Specific, high affinity binding sites for adenosine have been identified in the central nervous system. It is assumed that most of the physiological actions of adenosine are mediated via the interaction of endogenous adenosine with these receptors. But nothing is known about them in the pineal gland. We have demonstrated the presence of A2 adenosine receptors in rat pineal membranes and we have shown that these receptors are coupled positive! y with the adenylate cyclase unit and thus increased in vivo and in vitro the synthesis and the release of melatonin, the major hormone of the pineal gland. This hormone is synthetized after stimulation by adenosine and specific A2 adenosine agonists. Nor-adrénaline, an alpha 1 and beta-adrenergic agonist potentiates their activation. This result suggests an interaction between the transduction mecanisms implying the adenylate cyclase and the -phosphoinositides systems. We have confirmed the presence of A2 receptors in the healthy human pineal gland and we have observed a modification of the binding parameters in the pineal glands of victim suicides. At last, we have observed that physiological and environmental parameters such as aging, methylation processes, continuous light, modulate the adenosinergic neurotransmission in the brain and the pineal gland. ]

Au quotidien, notre organisme est soumis aux variations du milieu environnant perçues comme des facteurs de stress. En réponse à un stress, les catécholamines sécrétées par les cellules chromaffines de la glande médullosurrénale sont parmi les premières hormones à être libérées dans le sang. Leur sécrétion est sous le contrôle principal de l'acétylcholine à la synapse entre le nerf splanchnique et les cellules chromaffines ; la voie de communication intercellulaire médiée par des jonctions gap entre cellules chromaffines est également impliquée. Nous avons montré, dans des tranches de glandes surrénales de rats soumis à un protocole de stress au froid, que transmission synaptique et couplage électrique jonctionnel étaient augmentés. Plus précisément, l'augmentation du couplage électrique jonctionnel se caractérise par l'apparition d'un couplage robuste, qui permet la transmission de potentiels d'action. Par ailleurs, les taux d'expression des connexines 36 et 43 sont augmentés. Afin d'identifier les facteurs impliqués, nous avons caractérisé les effets de la vasopressine, neuropeptide impliqué dans le stress sur les cellules chromaffines et montré que le couplage jonctionnel mis en évidence par la présence de signaux calciques synchrones est augmenté par cette hormone. Nos travaux ont aussi révélé l'implication de nouveaux récepteurs nicotiniques alpha9/alpha10 dans la transmission synaptique. Chez le rat stressé, l'expression de ces récepteurs est augmentée et ils contribuent majoritairement au courant induit par l'acétylcholine. Ce travail décrit pour la première fois une plasticité du couplage jonctionnel de la glande médullosurrénale dans des conditions physiopathologiques. L'augmentation de la communication jonctionnelle entre cellules chromaffines et de l'activité synaptique améliore l'efficacité du couplage stimulation-sécrétion et représente un mécanisme endogène par lequel la médulla assure une libération de catécholamines appropriée en réponse au stress
An increase in circulating catecholamine levels is one of the mechanisms whereby organisms cope with stress. In the periphery, catecholamines mainly originate from the sympathoadrenal system. The secretion of catecholamines by adrenal chromaffin cells is a key event in response to stressors and it is chiefly controlled by trans-synaptically released acetylcholine from the splanchnic nerve endings. As supported by earlier results obtained in the laboratory, in addition to the central control through cholinergic innervation, a local gap junction-delineated route mediating intercellular electrical coupling between chromaffin cells is involved in the hormonal secretory process and represents an efficient complement to synaptic transmission able to amplify catecholamine release after synaptic stimulation. Whether these two communication pathways (i. E. Synaptic neurotransmission and gap junctional coupling) contribute to stress-evoked increased catecholamine secretion still remains unknown. We addressed this issue using acute adrenal slices from stressed rats (5 day-cold exposure). Our results show that in cold exposed rats, gap junctional communication undergoes a functional plasticity, as evidenced by an increased number of dye-coupled cells. Of a physiological interest is that this up-regulation results in the appearance of a robust electrical coupling between chromaffin cells that allows the transmission of action potentials between coupled cells. This enhancement of gap junctional communication parallels an increase in expression levels of connexin36 and connexin43 proteins. Both transcriptional and post-translational mechanisms are involved since Cx36 transcripts are increased in stressed rats and the expression of the scaffolding protein Zonula Occludens-1, known to interact with both Cx36 and Cx43, is also up-regulated. Consistent with an up-regulated coupling in stressed rats, the cytosolic Ca2+ concentration ([Ca2+]i) rise triggered in a single cell by an iontophoretic application of nicotine occurs simultaneously in several neighboring cells. We also showed that in response to stress, both chromaffin cell excitability and chemical transmission at the splanchnic nerve terminal-chromaffin cell synapses are increased. We next investigated whether vasopressin (VP), a neuropeptide known to play a key role in stress response, could be involved in increased gap junctional communication in stressed rats. Our results show that VP and d[Leu4,Lys8]VP, a V1b receptor specific agonist, increase the occurrence of gap junction-mediated synchronized [Ca2+]i transients between chromaffin cells, both in stressed and unstressed rats. This suggests that, although VP can up-regulate gap junctional coupling, it is unlikely the main factor involved in increased gap junctional communication observed in response to stress. Exposure to cold also enhances the synaptic neurotransmission between splanchnic nerve endings and chromaffin cells, as evidenced by an increase in spontaneous excitatory post-synaptic currents (sEPSCs). This correlates with an increased density of nerve fibers innervating the medulla. To go further, we examined whether the nAChR subtype formed by the combination of alpha9 and alpha10 subunits recently identified in isolated rat chromaffin cells is involved in this effect. By using a toxin (alpha-RgIa) to specifically block alpha9/alpha10 nAChRs, we showed that alpha9 /alpha10 nAChRs contribute to synaptic transmission. Interestingly, the expression level of alpha9 receptors is up-regulated in cold exposed rats. In addition, we show that in stressed rats, alpha9 /alpha10 nAChRs mainly contribute to acetylcholine-induced currents, as compared to alpha3 nAChRs that is the main nicotinic receptor activated in response to acetylcholine in control rats. This indicates that stress also induces nAChR plasticity, at least by acting on the expression level. In sum, the functional changes occurring both on gap junctional communication and on synaptic transmission converge to improve the stimulus-secretion coupling efficiency in the adrenal gland and may represent endogenous mechanisms by which the adrenal medullary tissue ensures appropriate increased catecholamine secretion in response to stressors

Doctor of Philosophy
Department of Plant Pathology
Anna E. Whitfield
Tomato spotted wilt virus (TSWV) is an economically important plant virus dependent on insects (thrips) for transmission to plant hosts. Like many animal-infecting viruses, TSWV replicates in the cells of its insect vector. The virus is an emergent disease threatening food and fiber crops worldwide. The aim of this work was to develop novel control strategies against TSWV through a better understanding of the virus-vector interaction. Previously, the TSWV GN protein was shown to be the viral attachment protein, a molecule mediating attachment of virus particles to the midgut epithelial cells of vector thrips. The specific goals of my research were to further examine the utility of disrupting the virus-vector interaction for effective virus control by exploiting GN properties, and to track the route of TSWV in thrips using confocal microscopy. To achieve these goals, I expressed soluble and insoluble forms of GN fused to green fluorescent protein (GFP) transiently and transgenically and examined their cellular localization in planta. GN::GFP recombinant protein localized to Golgi stacks throughout the cells as indicated by a punctate pattern or co-localization to a Golgi marker. In contrast, the soluble form of GN, GN-S::GFP, localized to the ER and apparently also to the cytoplasm. Virus acquisition and transmission assays with GN-S::GFP transgenic tomato plants demonstrated that transmission of TSWV by F. occidentalis was reduced by 35 to 100%. These results indicated that transgenic expression of GN-S in tomato plants may have the potential to prevent secondary spread of the virus. Novel features of the morphology of principal (PSGs) and tubular salivary glands (TSGs) of the insect vector F. occidentalis and of their infection with TSWV were described. The virus colonized different cell types and regions within the PSGs with variable intensity and distribution; and accumulated at the lumen of individual cells. The TSGs of F. occidentalis are proposed as a route for TSWV infection into the PSGs. The transgenic plants and the new knowledge of the virus vector interaction are promising tools to control TSWV and a model approach for the control of other vector-borne viruses.

Les differents aspects de la biologie de l'ecaille elasmoide ont ete precises chez le cichlide hemichromis bimaculatus, a l'aide de techniques histo/morphologiques et experimentales. Les resultats permettent de considerer ce materiel comme un modele favorable pour l'etude: de la mise en place d'une matrice collagenique orientee, de la mineralisation d'une telle trame organique, d'interactions epidermo-dermiques (en ontogenese ou en regeneration) et de l'origine phylogenetique de l'ecaille elasmoide

Observation du comportement de nymphose : rythme nocturne, de caractère exogène, avec choix du site conditionné par des facteurs physiques. Etude du comportement constructeur du cocon. Ultrastructure et fonctionnement des glandes sericigènes. Rôle du cocon dans la pénétration de la dessication des chrysalides.

Two isoforms of the tick Ixodes ricinus digestive peptidases cathepsins L1 and L3 are expressed also in salivary glands. In order to assess their role in this tissue, the specific antibodies against these peptidases were prepared by affinity chromatography and used for their detailed immuno-localization using cutting-edge methods of electron microscopy.

The forces that lead to the emergence of Trypanosoma cruzi, the etiologic agent of Chagas disease, are often distinct from those that maintain its transmission, and these are distinct again from those that allow the parasite to persist over decades. Just as kindling, logs, and coals all play discrete roles in the growth of a fire, a myriad of mammalian hosts contribute differently to epidemics of Trypanosoma. cruzi. Chagas disease affects millions of people in the Americas, and, through migration, thousands more on other continents. The agent of the disease, Trypanosoma cruzi, is a slender, highly-motile, unicellular parasite. T. cruzi does not migrate to the salivary glands of its insect vector–the blood-sucking triatomine insects–as many other vector-borne parasites do.

Mumps is an acute, systemic, highly infectious, communicable infection of children and young adults, caused by a paramyxovirus (with an RNA genome). Transmission is by airborne droplet spread. After an incubation period of 14–18 days, typical presentation is with fever, pain near the angle of the jaw, and swelling of the parotid glands. Complications include orchitis, meningitis, and encephalitis. Diagnosis is obvious clinically in cases with a contact history and parotitis, but serological (mumps-specific IgM and IgA) and RNA-based (RT-PCR) tests are used when this is not the case (e.g. the patient presenting with meningitis). Treatment is symptomatic. Prevention is by vaccination, often given as one component of a trivalent mumps/measles/rubella vaccine at 14–16 months of age. A follow-up vaccination is now recommended at 4–5 years of age.

Higher animals have four basic tissue types: epithelial tissue, connective tissue, nervous tissue, and muscle. Of these, nerve and muscle are grouped together as ‘excitable cells’ because the cell membrane has the ability to vary membrane ion conductance and membrane voltage so as to transmit meaningful signals within and between cells. Within excitable cells information is transmitted using either an amplitude-modulated (AM) code using slow, electrotonic potentials, or a frequency-modulated (FM) code when signalling is by action potentials. Much of the signalling between excitable cells occurs at chemical synapses where a chemical neurotransmitter is released from presynaptic cells and then interacts with postsynaptic membrane receptors. Clinical symptoms can arise when the release of chemical neurotransmitters is disturbed, or when availability of postsynaptic receptors is altered. Thus, a reduction in dopamine release from basal ganglia substantia nigra cells is found in Parkinson’s disease, while myasthenia gravis results from loss of nicotinic acetylcholine receptors at the neuromuscular junction of skeletal muscle. Sometimes transmission from cell to cell is not by chemical neurotransmitter but by electrical synapses, where gap-junctions provide direct electrical connectivity. Transmission between cardiac muscle cells occurs in this way. Some cardiac arrhythmias, such as Wolff –Parkinson–White syndrome, are a consequence of an abnormal path of electrical conduction between cardiac muscle fibres. Sensory cells on and within the body pass information via afferent pathways from the peripheral nervous system into the central nervous system (CNS). CNS processes and sensory information are integrated to produce outputs from the CNS. These outputs pass by various efferent routes to the effector organs: skeletal muscle, cardiac muscle, smooth muscle, and glands. It is through these effectors that the CNS is able to exert control over the body and to interact with the environment. Alterations of function anywhere in the afferent, integrative, or efferent aspects of the system, as well as defects in the effectors themselves, are likely to lead to significant clinical symptoms and signs. The efferent outflow from the CNS has two major components. One, the somatic nervous system, innervates only skeletal muscle. The other is the autonomic nervous system (ANS), which innervates cardiac muscle, smooth muscle, and the glands of the viscera and skin.