Papers by Gervasio Bechara
Revista Brasileira De Parasitologia Veterinaria, 2017
Immunogenic potential of Rhipicephalus (Boophilus) microplus aquaporin 1 against Rhipicephalus sa... more Immunogenic potential of Rhipicephalus (Boophilus) microplus aquaporin 1 against Rhipicephalus sanguineus in domestic dogs Potencial imunogênico da aquaporina 1 de Rhipicephalus (Boophilus) microplus contra o carrapato Rhipicephalus sanguineus em cães domésticos
Acta Tropica, Feb 1, 2017
The present study demonstrated the effects of dinotefuran (active ingredient of the acaricide Pro... more The present study demonstrated the effects of dinotefuran (active ingredient of the acaricide Protetor Pet ®) on the ovary and midgut cells of semi engorged R. sanguineus females exposed to different concentrations of this chemical. For this, 120 semi-engorged females were divided into four treatment groups with 30 individuals each: group I or control (distilled water), group II (5000 ppm), groups III (6250 ppm) and group IV (8334 ppm of dinotefuran). All the ticks were immersed in the different concentrations of dinotefuran or in distilled water for 5 min and then dried and kept in BOD incubator for 7 days. The results showed alterations mainly regarding the damaged cell structures, such as yolk granules, organelles and the plasma membrane of the germ cells. In addition, structures related with defense mechanisms were found, such as vacuoles, cytoskeletal filaments, and myelin figures in the germ cells. Damages in the generative cells of the midgut, alterations in the size of digestive cells, the number of endosomes, digestive vacuoles, digestive residues, lipid drops and organelles in the cytoplasm of the digestive cells and the presence of microvilli in the plasma membrane of these cells also demonstrate the progressive damages caused by the action of dinotefuran in the midgut and germ cells of R. sanguineus semi-engorged females. The concentrations applied partially impaired the digestive processes; and, without proper nutrition, all the ectoparasite's physiologic events are prevented from occurring, leading the individual to death. The germ cells were also damaged, and probably would not be able to advance in their development (I-V) and complete the vitellogenesis, which would affect the fertility of the female and consequently impede the formation of a new individual.
Transboundary and Emerging Diseases, Apr 1, 2010
Ars Veterinaria, 2010
Um dos maiores entraves na criação de avestruzes é relacionado à contaminação da região umbilical... more Um dos maiores entraves na criação de avestruzes é relacionado à contaminação da região umbilical de avestruzes recém-eclodidos. Neste trabalho, objetivou-se avaliar a cicatrização umbilical de avestruzes (Struthio camelus) mediante a antissepsia com clorexidina associada à secção total ou parcial do cordão umbilical. Foram utilizados 168 filhotes, cujo cordão umbilical foi seccionado totalmente ou 0,5 cm acima da sua inserção. A antissepsia da região umbilical consistiu na aplicação de clorexidina, em solução aquosa ou alcoólica, nas concentrações de 0,5%, 1,0% e 2,0%, durante três dias. Também foi incluído um grupo sem tratamento. A cicatrização umbilical foi avaliada aos 14 e 28 dias de idade do filhote. Os resultados mostraram que as soluções de clorexidina reduziram o risco de onfalite, sendo a solução alcoólica 2% a mais eficiente. A cicatrização foi mais rápida nas aves em que o cordão umbilical foi seccionado totalmente. Conclui-se que o uso de clorexidina para a antissepsia da região umbilical de avestruzes recémeclodidos é seguro e favorece a cicatrização umbilical, sendo necessário para uma maior efetividade remover o cordão umbilical na altura da sua inserção.
Revista Brasileira De Parasitologia Veterinaria, Feb 16, 2017
Immunogenic potential of Rhipicephalus (Boophilus) microplus aquaporin 1 against Rhipicephalus sa... more Immunogenic potential of Rhipicephalus (Boophilus) microplus aquaporin 1 against Rhipicephalus sanguineus in domestic dogs Potencial imunogênico da aquaporina 1 de Rhipicephalus (Boophilus) microplus contra o carrapato Rhipicephalus sanguineus em cães domésticos
Microscopy Research and Technique, Dec 30, 2010
The present study revealed unheard of data about the action of aqueous extracts of neem leaves (A... more The present study revealed unheard of data about the action of aqueous extracts of neem leaves (Azadirachta indica) on the vitellogenesis of Rhipicephalus sanguineus ticks, proving that these extracts in 10 and 20% concentrations do not have the potential to kill the females; however, in lower concentrations (10%) provokes great morphological alterations in germinative cells such as the emergence of extended cytoplasmic vacuolization areas as well as the fragmentation of the germinal vesicle, even in those oocytes which were in initial stages of development (I–III), showing that neem is a potent agent which acts impeding one of the main metabolic stages of the ticks, i.e., the reproduction. In oocytes in final stages of development (IV–V) azadirachtin (neem's active principle) caused significant reduction in the size and quantity of proteic granules of the yolk and the inversion of their localization where the smaller granules before inside the cell (normal oocyte) were posteriorly observed in the periphery, and the bigger ones in the central region. Thus, the study showed that the alterations found both in the oocytes and in the pedicel cells indicated that azadirachtin acts on the process of tick's reproduction and signalizes that this plant can be used in the future to control ticks with the advantage of not being aggressive to nontarget organism or the environment. Furthermore, data here obtained showed that the most significant efficiency of the aqueous extract of neem is related to the concentration of 10%, proving that higher doses would not be so efficient. Microsc. Res. Tech. 2010. © 2010 Wiley‐Liss, Inc.
Um dos maiores entraves na criação de avestruzes é relacionado à contaminação da região umbilical... more Um dos maiores entraves na criação de avestruzes é relacionado à contaminação da região umbilical de avestruzes recém-eclodidos. Neste trabalho, objetivou-se avaliar a cicatrização umbilical de avestruzes (Struthio camelus) mediante a antissepsia com clorexidina associada à secção total ou parcial do cordão umbilical. Foram utilizados 168 filhotes, cujo cordão umbilical foi seccionado totalmente ou 0,5 cm acima da sua inserção. A antissepsia da região umbilical consistiu na aplicação de clorexidina, em solução aquosa ou alcoólica, nas concentrações de 0,5%, 1,0% e 2,0%, durante três dias. Também foi incluído um grupo sem tratamento. A cicatrização umbilical foi avaliada aos 14 e 28 dias de idade do filhote. Os resultados mostraram que as soluções de clorexidina reduziram o risco de onfalite, sendo a solução alcoólica 2% a mais eficiente. A cicatrização foi mais rápida nas aves em que o cordão umbilical foi seccionado totalmente. Conclui-se que o uso de clorexidina para a antissepsia da região umbilical de avestruzes recémeclodidos é seguro e favorece a cicatrização umbilical, sendo necessário para uma maior efetividade remover o cordão umbilical na altura da sua inserção.
Experimental and Applied Acarology, Jun 1, 2017
Ticks and tick-borne diseases are of global importance and can cause serious economic losses to c... more Ticks and tick-borne diseases are of global importance and can cause serious economic losses to cattle-raising businesses. However, only few attempts have been made to describe the relationships between various cellular immune components and tick counts of, and therefore resistance to, Rhipicephalus microplus. The present study evaluated the late inflammatory cellular response and dermal dendritic cells at the attachment site in naturally presensitized bovines, artificially infested by R. microplus ticks. Twenty-two crossbred (Holstein 9 Gir) male experimental cattle were artificially infested with approximately 10,000 larvae of R. microplus. Parasitic infestation was determined by counting the engorged female ticks (4.5-8.0 mm in diameter) at the 21st day after artificial infestation. Biopsies (6 mm) were taken prior to the infestation and along with the tick count from the right pinna of each animal, and examined with histological techniques and immunohistochemistry using S100 protein. Inflammatory cell counts were conducted in the sections stained with the May-Grünwald Giemsa technique, and immunostained dermal dendritic cells were evaluated and classified in scores ranging from 0 to 4. An average of 39.2 ticks per animal was found. Eosinophils (47.8%) constituted the major portion of the cellular infiltrate, followed by mononuclear cells (28.3%), neutrophils (14.4%), and basophils (0% to approximately 2%). The dendritic cell count shows a considerable population in the dermis, with pre-and post-infestation mean scores of 1.54 and 1.89, respectively; these scores were not significantly different. Our results pointed out the importance of the cellular response in the cattle resistance to ticks.
Arquivo Brasileiro De Medicina Veterinaria E Zootecnia, 1996
Brazilian Journal of Veterinary Pathology, 2008
The number of dermal mast cells in several European and Zebu cattle breeds was determined and cor... more The number of dermal mast cells in several European and Zebu cattle breeds was determined and correlated with the tick load. Breeds included European registered and non-registered Holstein, Brown-Swiss and Jersey cows, Zebu (Nelore and Gyr) and crossbred cows with either high or low tick infestations. Animals were naturally infested with Rhipicephalus (Boophilus) microplus and evaluated at regular time intervals for tick attachment and feeding. Ear biopsies were taken and processed according to routine histology for mast cell countings carried out on both the upper and deep dermis. The average cell counts were then correlated with the number of engorged ticks attached to host. Nelore cows presented the largest mast cells countings/mm2 (139.42; P <0.05), while surprisingly Gyr showed similar number of cells (61.73) as the Holstein (48.76) and Brown-Swiss (67.31) ones. Jersey cows presented the smallest cell countings (29.32) despite their greater resistance to tick infestation as compared to Holstein and Brown-Swiss. There was a negative correlation (r=-0.21, P <0.01) between the number of cells in the upper dermis and tick counts when all data (n= 155) were analyzed in a single correlation plane, irrespective of the breed. These results confirm the important role played by mast cells in bovine resistance to the cattle tick R. microplus.
Revista Brasileira De Parasitologia Veterinaria, 2023
This is an Open Access article distributed under the terms of the Creative Commons Attribution Li... more This is an Open Access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Infestation of rabbits with just-molted adults of the cattle tick Rhipicephalus microplus: biological parameters and efficiency Infestação de coelhos com adultos recém-mudados do carrapato-do-boi Rhipicephalus microplus
Journal of Microscopy and Ultrastructure, Jun 1, 2015
This study describes the changes undergone by cells of the salivary glands of unfed and feeding (... more This study describes the changes undergone by cells of the salivary glands of unfed and feeding (at day two and four post-attachment) Rhipicephalus sanguineus males, as well as new cell types. In unfed males, types I and II acini are observed with cells ''undifferentiated'', undefined 1 and 2 (the latter, with atypical granules), a, c1 and c3; type III is composed of cells d and e; and type IV present cells g. In males at day two postattachment, type I acini exhibit the same morphology of unfed individuals. An increase in size is observed in types II, III, and IV, as cells are filled with secretion granules. Some granules are still undergoing maturation. In type II acinus, cells a, b and c1-c8 are observed. Cells c7 and c8 are described for the first time. Cells c7 are termed as such due to the addition of polysaccharides in the composition of the secretion granules (in unfed individuals, they are termed undefined 1). Type III acini exhibit cells d and e completely filled with granules, and in type IV, cells g contain granules in several stages of maturation. In males at day four post-attachment, type I acini do not exhibit changes. Granular acini exhibit cells with fewer secretion granules, which are already mature. In type II acini, cells a, b, c1-c5 are present, type III exhibit cells d and e, and type IV contain cells g with little or no secretion. This study shows that in the salivary glands of R. sanguineus males, cells a, c1, and c3 of type II acinus, and cells d and e of type III do not exhibit changes in granular content, remaining continuously active during the entire feeding period. This indicates that during the intervals among feeding stages, gland cells reacquire the same characteristics found in unfed individuals, suggesting that they undergo reprogramming to be active in the next cycle.
Brazilian Journal of Medical and Biological Research, 1985
UNIV ESTADUAL PAULISTA JULIO MESQUITA FILHO,FAC CIENCIAS AGR & VET,DEPT PATOL VET,JABOTICABAL... more UNIV ESTADUAL PAULISTA JULIO MESQUITA FILHO,FAC CIENCIAS AGR & VET,DEPT PATOL VET,JABOTICABAL,SP,BRAZIL
Arquivo Brasileiro De Medicina Veterinaria E Zootecnia, Dec 1, 1996
Endotoxemia por lipopolissacarídeo de Escherichia coli, em eqüinos: efeitos de antiinflamatórios ... more Endotoxemia por lipopolissacarídeo de Escherichia coli, em eqüinos: efeitos de antiinflamatórios nas concentrações sérica e peritoneal do fator de necrose tumoral alfa (TNF-α) [Escherichia coli lipopolisacharide (LPS) induced endotoxemia in horses: effects of anti-inflammatory drugs on seric and peritoneal tumor necrosis factor alpha (TNF-α) concentrations
Journal of the South African Veterinary Association, Jun 18, 2004
Laboratory animals exposed to feeding ticks develop resistance which is reflected by a decline in... more Laboratory animals exposed to feeding ticks develop resistance which is reflected by a decline in tick engorgement weight, egg-laying by adults and reduced egg viability. Serum antibodies from these hosts and their reaction with tick antigens have been detected by different methods, including precipitation techniques, immunofluorescent techniques, ELISA and Western blots. However, little is known about the effects of antibodies on ticks that engorge on resistant hosts, or which tissues of the tick body are possibly immunogenic. Some researchers, using immunohistochemistry, have detected host antibodies in the gut, salivary glands and haemolymph of ticks engorged on resistant animals. The same technique has helped considerably in determining antigenic sites or antibody targets in other arthropods. Consequently, immunohistochemistry techniques were used in this study to detect cross-reactivity between sera raised against Amblyomma cajennense (Fabricius, 1787) with Amblyomma hebraeum (Koch, 1844), and vice versa. The results show the existence of shared antigens between the 2 tick species. In general, our results point more to a 1-way cross-reactivity of A. hebraeum with A. cajennense than a reciprocal crossreactivity, suggesting that A. hebraeum is more immunogenic than A. cajennense.
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Papers by Gervasio Bechara