Comparative evaluation of juvenoids for control of cat fleas (Siphonaptera : Pulicidae) in topsoil

The efficacy of a photostable formulation of methoprene and two photostable juvenoids, fenoxycarb and pyriproxyfen, and their residual activity in inhibiting the emergence of adult cat fleas, Ctenocephalides felis (Bouche), was studied in topsoil. Nursery pots composed of clay, peat, and plastic, and wooden flats were used to hold soil samples. Treated soil samples were exposed to sunlight during the 63-d study period. Methoprene was as effective as fenoxycarb and pyriproxyfen against cat fleas for up to 42 d in clay, peat, and plastic pots at a concentration of 64.56 mg (AI) /m(2) (6 mg [AI] /ft(2)), but its activity declined significantly thereafter. In contrast, fenoxycarb and pyriproxyfen showed strong residual activity for the entire 63 d. The activity of methoprene declined even more rapidly over time in wooden flats, while at the same concentrations the other two juvenoids showed significant residual activity for 63 d. Clay, peat, and plastic pots were therefore considered to be equally effective for evaluating the outdoor efficacy of juvenoids in comparison to the wooden flats. However, results obtained with wooden flats may be more realistic when testing residual activity of volatile chemicals such as methoprene. Fenoxycarb and pyriproxyfen showed strong efficacy and residual activity at concentrations of 8.07, 16.14, and 32.28 mg (AI) /m(2), whereas methoprene did not cause a significant reduction of adult emergence at levels below 64.56 mg (AI) /m(2). LC50 values for methoprene, fenoxycarb, and pyriproxyfen needed for preventing flea emergence when applied to topsoil were estimated to be 0.643, 0.031, and 0.028 ppm, respectively.

Differential distribution of tau proteins in developing cat cerebral cortex and corpus callosum.

During the postnatal development of cat visual cortex and corpus callosum the molecular composition of tau proteins varied with age. In both structures, they changed between postnatal days 19 and 39 from a set of two juvenile forms to a set of at least two adult variants with higher molecular weights. During the first postnatal week, tau proteins were detectable with TAU-1 antibody in axons of corpus callosum and visual cortex, and in some perikarya and dendrites in the visual cortex. At later ages, tau proteins were located exclusively within axons in all cortical layers and in the corpus callosum. Dephosphorylation of postnatal day 11 cortical tissue by alkaline phosphatase strongly increased tau protein immunoreactivity on Western blots and in numerous perikarya and dendrites in all cortical layers, in sections, suggesting that some tau forms had been unmasked. During postnatal development the intensity of this phosphate-dependent somatodendritic staining decreased, but remained in a few neurons in cortical layers II and III. On blots, the immunoreactivity of adult tau to TAU-1 was only marginally increased by dephosphorylation. Other tau antibodies (TAU-2, B19 and BR133) recognized two juvenile and two adult cat tau proteins on blots, and localized tau in axons or perikarya and dendrites in tissue untreated with alkaline phosphatase. Tau proteins in mature tissue were soluble and not associated with detergent-resistant structures. Furthermore, dephosphorylation by alkaline phosphatase resulted in the appearance of more tau proteins in soluble fractions. Therefore tau proteins seem to alter their degree of phosphorylation during development. This could affect microtubule stability as well as influence axonal and dendritic differentiation.

Auditory Neurons with Transitory Axons to Visual Areas Form Short Permanent Projections.

The kitten's auditory cortex (including the first and second auditory fields AI and AII) is known to send transient axons to either ipsi- or contralateral visual areas 17 and 18. By the end of the first postnatal month the transitory axons, but not their neurons of origin, are eliminated. Here we investigated where these neurons project after the elimination of the transitory axon. Eighteen kittens received early (postnatal day (pd) 2 - 5) injections of long lasting retrograde fluorescent traces in visual areas 17 and 18 and late (pd 35 - 64) injections of other retrograde fluorescent tracers in either hemisphere, mostly in areas known to receive projections from AI and AII in the adult cat. The middle ectosylvian gyrus was analysed for double-labelled neurons in the region corresponding approximately to AI and AII. Late injections in the contralateral (to the analysed AI, AII) hemisphere including all of the known auditory areas, as well as some visual and 'association' areas, did not relabel neurons which had had transient projections to either ipsi- or contralateral visual areas 17 - 18. Thus, AI and AII neurons after eliminating their transient juvenile projections to visual areas 17 and 18 do not project to the other hemisphere. In contrast, relabelling was obtained with late injections in several locations in the ipsilateral hemisphere; it was expressed as per cent of the population labelled by the early injections. Few neurons (0 - 2.5%) were relabelled by large injections in the caudal part of the posterior ectosylvian gyrus and the adjacent posterior suprasylvian sulcus (areas DP, P, VP). Multiple injections in the middle ectosylvian gyrus relabelled a considerably larger percentage of neurons (13%). Single small injections in the middle ectosylvian gyrus (areas AI, AII), the caudal part of the anterior ectosylvian gyrus and the rostral part of the posterior ectosylvian gyrus relabelled 3.1 - 7.0% of neurons. These neurons were generally near (<2.0 mm) the outer border of the late injection sites. Neurons with transient projections to ipsi- or contralateral visual areas 17 and 18 were relabelled in similar proportions by late injections at any given location. Thus, AI or AII neurons which send a transitory axon to ipsi- or contralateral visual areas 17 and 18 are most likely to form short permanent cortical connections. In that respect, they are similar to medial area 17 neurons that form transitory callosal axons and short permanent axons to ipsilateral visual areas 17 and 18.

Codage de l’information visuelle par la plasticité et la synchronisation des réponses neuronales dans le cortex visuel primaire du chat

Les systèmes sensoriels encodent l’information sur notre environnement sous la forme d’impulsions électriques qui se propagent dans des réseaux de neurones. Élucider le code neuronal – les principes par lesquels l’information est représentée dans l’activité des neurones – est une question fondamentale des neurosciences. Cette thèse constituée de 3 études (E) s’intéresse à deux types de codes, la synchronisation et l’adaptation, dans les neurones du cortex visuel primaire (V1) du chat. Au niveau de V1, les neurones sont sélectifs pour des propriétés comme l’orientation des contours, la direction et la vitesse du mouvement. Chaque neurone ayant une combinaison de propriétés pour laquelle sa réponse est maximale, l’information se retrouve distribuée dans différents neurones situés dans diverses colonnes et aires corticales. Un mécanisme potentiel pour relier l’activité de neurones répondant à des items eux-mêmes reliés (e.g. deux contours appartenant au même objet) est la synchronisation de leur activité. Cependant, le type de relations potentiellement encodées par la synchronisation n’est pas entièrement clair (E1). Une autre stratégie de codage consiste en des changements transitoires des propriétés de réponse des neurones en fonction de l’environnement (adaptation). Cette plasticité est présente chez le chat adulte, les neurones de V1 changeant d’orientation préférée après exposition à une orientation non préférée. Cependant, on ignore si des neurones spatialement proches exhibent une plasticité comparable (E2). Finalement, nous avons étudié la dynamique de la relation entre synchronisation et plasticité des propriétés de réponse (E3). Résultats principaux — (E1) Nous avons montré que deux stimuli en mouvement soit convergent soit divergent élicitent plus de synchronisation entre les neurones de V1 que deux stimuli avec la même direction. La fréquence de décharge n’était en revanche pas différente en fonction du type de stimulus. Dans ce cas, la synchronisation semble coder pour la relation de cocircularité dont le mouvement convergent (centripète) et divergent (centrifuge) sont deux cas particuliers, et ainsi pourrait jouer un rôle dans l’intégration des contours. Cela indique que la synchronisation code pour une information qui n’est pas présente dans la fréquence de décharge des neurones. (E2) Après exposition à une orientation non préférée, les neurones changent d’orientation préférée dans la même direction que leurs voisins dans 75% des cas. Plusieurs propriétés de réponse des neurones de V1 dépendent de leur localisation dans la carte fonctionnelle corticale pour l’orientation. Les comportements plus diversifiés des 25% de neurones restants sont le fait de différences fonctionnelles que nous avons observé et qui suggèrent une localisation corticale particulière, les singularités, tandis que la majorité des neurones semblent situés dans les domaines d’iso-orientation. (E3) Après adaptation, les paires de neurones dont les propriétés de réponse deviennent plus similaires montrent une synchronisation accrue. Après récupération, la synchronisation retourne à son niveau initial. Par conséquent, la synchronisation semble refléter de façon dynamique la similarité des propriétés de réponse des neurones. Conclusions — Cette thèse contribue à notre connaissance des capacités d’adaptation de notre système visuel à un environnement changeant. Nous proposons également des données originales liées au rôle potentiel de la synchronisation. En particulier, la synchronisation semble capable de coder des relations entre objets similaires ou dissimilaires, suggérant l’existence d’assemblées neuronales superposées.

Analyse des réponses neuronales du cortex visuel primaire du chat à la fréquence spatiale suite à des adaptations répétées

Les neurones du cortex visuel primaire (aire 17) du chat adulte répondent de manière sélective à différentes propriétés d’une image comme l’orientation, le contraste ou la fréquence spatiale. Cette sélectivité se manifeste par une réponse sous forme de potentiels d’action dans les neurones visuels lors de la présentation d’une barre lumineuse de forme allongée dans les champs récepteurs de ces neurones. La fréquence spatiale (FS) se mesure en cycles par degré (cyc./deg.) et se définit par la quantité de barres lumineuses claires et sombres présentées à une distance précise des yeux. Par ailleurs, jusqu’à récemment, l’organisation corticale chez l’adulte était considérée immuable suite à la période critique post-natale. Or, lors de l'imposition d'un stimulus non préféré, nous avons observé un phénomène d'entrainement sous forme d'un déplacement de la courbe de sélectivité à la suite de l'imposition d'une FS non-préférée différente de la fréquence spatiale optimale du neurone. Une deuxième adaptation à la même FS non-préférée induit une réponse neuronale différente par rapport à la première imposition. Ce phénomène de "gain cortical" avait déjà été observé dans le cortex visuel primaire pour ce qui est de la sélectivité à l'orientation des barres lumineuses, mais non pour la fréquence spatiale. Une telle plasticité à court terme pourrait être le corrélat neuronal d'une modulation de la pondération relative du poids des afférences synaptiques.

Coinfection of Leishmania chagasi with Toxoplasma gondii, Feline Immunodeficiency Virus (FIV) and Feline Leukemia Virus (FeLV) in cats from an endemic area of zoonotic visceral leishmaniasis

The aim of the present study was to determine the coinfection of Leishmania sp. with Toxoplasma gondii, Feline Immunodeficiency Virus (FIV) and Feline Leukemia Virus (FeLV) in a population of cats from an endemic area for zoonotic visceral leishmaniasis. An overall 66/302 (21.85%) cats were found positive for Leishmania sp., with infection determined by direct parasitological examination in 30/302(9.93%), by serology in 46/302(15.23%) and by both in 10/302 (3.31%) cats. Real time PCR followed by amplicon sequencing successfully confirmed Leishmania infantum (syn Leishmania chagasi) infection. Out of the Leishmania infected cats, coinfection with FIV was observed in 12/66(18.18%), with T. gondii in 17/66 (25.75%) and with both agents in 5/66(7.58%) cats. FeLV was found only in a single adult cat with no Leishmania infection. A positive association was observed in coinfection of Leishmania and FIV (p < 0.0001), but not with T. gondii (p > 0.05). In conclusion, cats living in endemic areas of visceral leishmaniasis are significantly more likely to be coinfected with Fly, which may present confounding clinical signs and therefore cats in such areas should be always carefully screened for coinfections. (C) 2012 Elsevier B.V. All rights reserved.

Ultrassonografia abdominal de cães e gatos hígidos, adultos e filhotes

Pós-graduação em Medicina Veterinária - FMVZ

Coinfection of Leishmania chagasi with Toxoplasma gondii, Feline Immunodeficiency Virus (FIV) and Feline Leukemia Virus (FeLV) in cats from an endemic area of zoonotic visceral leishmaniasis

The aim of the present study was to determine the coinfection of Leishmania sp. with Toxoplasma gondii, Feline Immunodeficiency Virus (FIV) and Feline Leukemia Virus (FeLV) in a population of cats from an endemic area for zoonotic visceral leishmaniasis. An overall 66/302 (21.85%) cats were found positive for Leishmania sp., with infection determined by direct parasitological examination in 30/302(9.93%), by serology in 46/302(15.23%) and by both in 10/302 (3.31%) cats. Real time PCR followed by amplicon sequencing successfully confirmed Leishmania infantum (syn Leishmania chagasi) infection. Out of the Leishmania infected cats, coinfection with FIV was observed in 12/66(18.18%), with T. gondii in 17/66 (25.75%) and with both agents in 5/66(7.58%) cats. FeLV was found only in a single adult cat with no Leishmania infection. A positive association was observed in coinfection of Leishmania and FIV (p < 0.0001), but not with T. gondii (p > 0.05). In conclusion, cats living in endemic areas of visceral leishmaniasis are significantly more likely to be coinfected with Fly, which may present confounding clinical signs and therefore cats in such areas should be always carefully screened for coinfections. (C) 2012 Elsevier B.V. All rights reserved.

Topographic plasticity in primary visual cortex is mediated by local corticocortical connections

The placement of monocular laser lesions in the adult cat retina produces a lesion projection zone (LPZ) in primary visual cortex (V1) in which the majority of neurons have a normally located receptive field (RF) for stimulation of the intact eye and an ectopically located RF ( displaced to intact retina at the edge of the lesion) for stimulation of the lesioned eye. Animals that had such lesions for 14 - 85 d were studied under halothane and nitrous oxide anesthesia with conventional neurophysiological recording techniques and stimulation of moving light bars. Previous work suggested that a candidate source of input, which could account for the development of the ectopic RFs, was long-range horizontal connections within V1. The critical contribution of such input was examined by placing a pipette containing the neurotoxin kainic acid at a site in the normal V1 visual representation that overlapped with the ectopic RF recorded at a site within the LPZ. Continuation of well defined responses to stimulation of the intact eye served as a control against direct effects of the kainic acid at the LPZ recording site. In six of seven cases examined, kainic acid deactivation of neurons at the injection site blocked responsiveness to lesioned-eye stimulation at the ectopic RF for the LPZ recording site. We therefore conclude that long-range horizontal projections contribute to the dominant input underlying the capacity for retinal lesion-induced plasticity in V1.

Structural alterations in adult rat carotid bodies exposed to hyperbaric oxygenation

Inhibition of carotid body (CB) function is the main mechanism involved in the attenuation of respiratory drive observed during hyperoxia However, only a few studies at 5 0 atmospheres absolutes (ATA) have analyzed carotid body structure or function in hyperbaric oxygenation (HBO(2)) situations We hypothesized that rats will present CB structural alterations when exposed to different lower hyperbaric oxygen doses enough to alter their chemosensory response to hypoxia Methods - Twenty-one adult male Wistar rats, divided into three groups, were maintained in room air or exposed to O(2) at 2 4 or 3 0 ATA for six hours Histological, ultrastructural and immunohistochemical analyses for neuronal nitric oxide synthase (nNOS) and F2-isoprostane were performed in the excised CBs Results - Histological analyses revealed signs of intracellular edema in animals exposed to both conditions, but this was more marked in the 3 0 ATA group, which showed ultrastructural alterations at the mitochondrial level There was a significant increase in the volume density of intraglomic-congested capillaries in the 3 0 ATA group associated with an arteriolar vasoconstriction In the 2 4 ATA group, there was a relative increase of glomic light cells and a decrease of glomic progenitor cells Additionally, there was a stronger immunoreactivity for F2-isoprostane in the 3 0 ATA O(2)-exposed carotid bodies The glomic cells stained positive for nNOS, but no difference was observed between the groups Our results show that high 02 exposures may induce structural alterations in glomic cells with signs of lipid peroxidation We further suggest that deviation of blood flow toward intraglomic capillaries occurs in hyperbaric hyperoxia

Prenatal LPS exposure reduces olfactory perception in neonatal and adult rats

Prenatal lipopolysaccharide (LPS) exposure causes reproductive, behavioral and neurochemical defects in both dams and pups. The present study evaluated male rats prenatally treated with LPS for behavioral and neurological effects related to the olfactory system, which is the main sensorial path in rodents. Pregnant Wistar rats received 100 mu g/kg of LPS intraperitoneally (i.p.) on gestational day (GD) 9.5, and maternal behavior was evaluated. Pups were evaluated for (1) maternal odor preference, (2) aversion to cat odor, (3) monoamine levels and turnover in the olfactory bulb (OB) and (4) protein expression (via immunoblotting) within the OB dopaminergic system and glial cells. Results showed that prenatal LPS exposure impaired maternal preference and cat odor aversion and decreased dopamine (DA) levels in the OB. This dopaminergic impairment may have been due to defects in another brain area given that protein expression of the first enzyme in the DA biosynthetic pathway was unchanged in the OB. Moreover, there was no change in the protein expression of the DA receptors. The fact that the number of astrocytes and microglia was not increased suggests that prenatal LPS did not induce neuroinflammation in the OB. Furthermore, given that maternal care was not impaired, abnormalities in the offspring were not the result of reduced maternal care. (C) 2011 Elsevier Inc. All rights reserved.

Surgical extraction of transplanted adult Dirofilaria immitis in cats

A jugular venotomy technique was developed to attempt extraction of Dirofilaria immitis in cats. Seven cats were first examined by cardiac ultrasound to establish the location of adult D. immitis that had been inserted by jugular venotomy. The efficiency of an extractor catheter in surgically removing filariae similarly inserted into 13 experimental cats was then assessed. A mean extraction success rate of 96% was achieved. This technique would seem to be worthy of clinical use provided the filariae are in the right atrial area.

Exogenous induction of ovarian activity and ovulation and transfer of fresh embryos of domestic cat (Felis catus)

The objective of the present study was the exogenous stimulation of ovarian activity and definition of embryo collection, and transfer protocols, in the domestic cat for potential application in non-domestic endangered species. Sixteen adult queens and two adult male reproducers kept in the experimental cat house at the Morphology sector at the Veterinary Department (DVT), UFV, were used in this study. All the queens received a single application of 150 IU Equine Chorionic Gonadotropin (eCG) in the post estrus to induce ovarian activity and 80 to 84 hours later, received a single application of 100 UI Human Chorionic Gonadotropin (hCG) to induce ovulation. After hCG application, only the donor queens were naturally mated. The receptor queens received extra stimulus for induction of ovulation through manipulation of an intravaginal swab. Five to six days after hCG application, the donor queens were subjected to a laparotomy for embryo collection that was performed by trans-horn uterine washing. On average, six embryos were surgically inovulated. They were classified as type I and III compact morula and blastocysts in four receptor queens. Three animals presented pregnancy confirmed by ultrasound at day 36 and two of these animals gave birth to litters of two and four offsprings, respectively, at 66 and 63 days after induction of ovulation. Except for one still birth, all the offspring developed normally.

Severe occlusive vasculitis as a complication of cat scratch disease

BACKGROUND: The purpose of this communication is to report a severe occlusive vasculitis as a complication of cat scratch. HISTORY AND SIGNS: A 34-year-old Hispanic woman presented with a sudden visual loss of the right eye associated with shivers, high fever and arthritis which developed 2 months after a cat's bite. Fundus examination showed papillitis and a palor of the paramacular zone of the retina. Fluorescein angiography revealed multiple arterial and venous vasculitic occlusions. THERAPY AND OUTCOME: Auto-immune disease and endocarditis were ruled out by an extensive medical work-up.The diagnosis of Bartonella henselae was confirmed by a positive serology. A systemic antibiotherapy with azithromycin, doxycyclin, rifampicin and steroid therapy resulted in a good clinical response, including a rapid visual recovery with a visual acuity of 20/20 and no relapse of the disease at 6 months follow-up. CONCLUSIONS: Ocular complications associated with cat scratch disease may include vasculitis with both arterial and venous occlusions causing severe visual loss.

Differential distribution of tau proteins in developing cat cerebellum.

The differential distribution and phosphorylation of tau proteins in cat cerebellum was studied with two well characterized antibodies, TAU-1 and TAU-2. TAU-1 detects tau proteins in axons, and the epitope in perikarya and dendrites is masked by phosphorylation. TAU-2 detects a phosphorylation-independent epitope on tau proteins. The molecular composition of tau proteins in the range of 45 kD to 64 kD at birth changed after the first postnatal month to a set of several adult variants of higher molecular weights in the range of 59 kD to 95 kD. The appearance of tau proteins in subsets of axons corresponds to the axonal maturation of cerebellar local-circuit neurons in granular and molecular layers and confirms previous studies. Tau proteins were also identified in synapses by immunofluorescent double-staining with synapsin I, located in the pinceau around the Purkinje cells, and in glomeruli. Dephosphorylation of juvenile cerebellar tissue by alkaline phosphatase indicated indirectly the presence of differentially phosphorylated tau forms mainly in juvenile ages. Additional TAU-1 immunoreactivity was unmasked in numerous perikarya and dendrites of stellate cells, and in cell bodies of granule cells. Purkinje cell bodies were stained transiently at juvenile ages. During postnatal development, the intensity of the phosphate-dependent staining decreased, suggesting that phosphorylation of tau proteins in perikarya and dendrites may be essential for early steps in neuronal morphogenesis during cat cerebellum development.