Trypanosoma cruzi: blood parasitism kinetics and their correlation with heart parasitism intensity during long-term infection of Beagle dogs

The goals of the present study were to evaluate the kinetics of blood parasitism by examination of fresh blood, blood culture (BC) and PCR assays and their correlation with heart parasitism during two years of infection in Beagle dogs inoculated with the Be-78, Y and ABC Trypanosoma cruzi strains. Our results showed that the parasite or its kDNA is easily detected during the acute phase in all infected animals. On the other hand, a reduced number of positive tests were verified during the chronic phase of the infection. The frequency of positive tests was correlated with T. cruzi strain. The percentage of positive BC and blood PCR performed in samples from animals inoculated with Be-78 and ABC strains were similar and significantly larger in relation to animals infected with the Y strain.Comparison of the positivity of PCR tests performed using blood and heart tissue samples obtained two years after infection showed two different patterns associated with the inoculated T. cruzi strain: (1) high PCR positivity for both blood and tissue was observed in animals infected with Be-78 or ABC strains; (2) lower and higher PCR positivity for the blood and tissue, respectively, was detected in animals infected with Y strains. These data suggest that the sensitivity of BC and blood PCR was T. cruzi strain dependent and, in contrast, the heart tissue PCR revealed higher sensitivity regardless of the parasite stock.

Myenteric plexus is differentially affected by infection with distinct Trypanosoma cruzi strains in Beagle dogs

Chagasic megaoesophagus and megacolon are characterised by motor abnormalities related to enteric nervous system lesions and their development seems to be related to geographic distribution of distinct Trypanosoma cruzi subpopulations. Beagle dogs were infected with Y or Berenice-78 (Be-78) T. cruzi strains and necropsied during the acute or chronic phase of experimental disease for post mortem histopathological evaluation of the oesophagus and colon. Both strains infected the oesophagus and colon and caused an inflammatory response during the acute phase. In the chronic phase, inflammatory process was observed exclusively in the Be-78 infected animals, possibly due to a parasitism persistent only in this group. Myenteric denervation occurred during the acute phase of infection for both strains, but persisted chronically only in Be-78 infected animals. Glial cell involvement occurred earlier in animals infected with the Y strain, while animals infected with the Be-78 strain showed reduced glial fibrillary acidic protein immunoreactive area of enteric glial cells in the chronic phase. These results suggest that although both strains cause lesions in the digestive tract, the Y strain is associated with early control of the lesion, while the Be-78 strain results in progressive gut lesions in this model.

Physiological and behavioural effects of dextroamphetamine on Beagle dogs : a placebo controlled study

Plusieurs articles scientifiques et manuels de référence en médecine comportementale distinguent l'hyperactivité ou hyperkinésie de l’activité excessive en évaluant la réponse physiologique et comportementale des chiens suite à l’administration per os de 0.2 à 1.0 mg/kg de dextroamphétamine. Selon ces références, le chien atteint d’un syndrome hyperactif ou hyperkinésie, répondra de façon paradoxale à cette médication par une diminution de l’activité motrice accompagnée d’une réduction minimale de 15% de la fréquence respiratoire et de la fréquence cardiaque. L’objectif de la présente étude était de mesurer la variation de la température corporelle, de la fréquence cardiaque, de l’activité motrice et de différents comportements spécifiques chez un groupe de Beagles ayant reçu de la dextroamphétamine. La fiabilité d'un accéléromètre comme mesure objective d’activité motrice a aussi été évaluée. Dans le cadre de cette étude croisée contrôlée par placebo, douze Beagles de la colonie de recherche âgés entre 13 et 20 mois ont reçu une dose orale de 0.2 mg/kg de dextroamphétamine. Le moniteur cardiaque Polar® et un accéléromètre Actical® ont été utilisés pour enregistrer la fréquence cardiaque et l’activité motrice avant et après l’administration de la médication. La durée de chacun des comportements spécifiques a été compilée à l’aide du logiciel Noldus® et la température corporelle a été prise par thermomètre rectal. Le modèle équilibré de mesures répétées indique que les sujets ayant reçu la dextroamphétamine montrent une réduction significative (p = 0.044) de leur fréquence cardiaque comparativement aux chiens ayant reçu le placebo. Aucune variation significative n'a été observée concernant la température corporelle, l'activité motrice, et les autres comportements (léchage des babines, halètements, et bâillements) suite à l’administration de la dextroamphétamine. Une corrélation significative, linéaire et positive (p < 0,0001) entre les périodes de mouvements observées (vidéo) et les mesures d’activité enregistrées par l’accéléromètre a été observée. Les résultats de cette étude indiquent que les Beagles peuvent afficher des effets paradoxaux dans les 90 minutes suivant l’administration per os de dextroamphétamine à raison de 0.2 mg/kg.

Comparative safety respiratory pharmacology : validation of a head-out plethysmograph – pneumotachometer testing device in male Sprague–Dawley rats, Beagle dogs and Cynomolgus monkeys

Le but de cette étude était d’évaluer les qualifications de performance du système FlexiWare® chez le rat male Sprague Dawley et le singe Cynomolgus éveillés, ainsi que chez le chien Beagle éveillé et anesthésié, suite à l’administration de produits ayant une activité pharmacologique connue. Les produits utilisés incluaient l’albutérol administré par inhalation, la méthacholine, et le rémifentanil administrés par voie intraveineuse. Une solution saline administré par voie intraveneuse, a été utilisée comme substance témoin. Différentes variables ont servi à évaluer la réponse des animaux (rats, chien, singe). Ces dernières comprenaient la fréquence respiratoire (RR), le volume courant (TV), la ventilation minute (MV). Des paramètres additionnels ont été évalués chez le rat, soit les temps d’inspiration (IT) et d’expiration (ET), le temps du pic de débit expiratoire, les pics de débits inspiratoire et expiratoire, le ratio inspiratoire:expiratoire (I:E), le ratio inspiratoire sur respiration totale (I:TB), et l’écoulement expiratoire moyen (EF50). Les résultats obtenus ont démontré que le système FlexiWare® était suffisamment sensible et spécifique pour dépister, chez les espèces animales utilisées, les effets bronchodilateur, bronchoconstricteur et dépresseur central des substances testées. Il pourrait faire partie des méthodes (ICH 2000) utilisées en pharmacologie de sécurité lors de l’évaluation de substances pharmacologiques sur le système respiratoire des animaux de laboratoire. Les espèces animales utilisées ont semblé s’adapter aisément aux procédures de contention. Les paramètres évalués, RR, TV et MV ont permis de caractériser la réponse des animaux suite à l’administration de produits pharmacologiques à effets connus, judicieusement complétés par les variables de débit. L’ajout de paramètres du temps n’était pas primordiale pour détecter les effets des drogues, mais offre des outils complémentaires d’interpréter les changements physiologiques. Cependant, chez le rat conscient, la période d’évaluation ne devrait pas s’étendre au-delà d’une période de deux heures post traitement. Ces études constituent une évaluation des qualifications de performance de cet appareil et ont démontré de manière originale, la validation concurrentielle, en terme de précision (sensibilité et spécificité) et fiabilité pour différentes variables et sur différentes espèces.

Old beagle dogs have lower faecal concentrations of some fermentation products and lower peripheral lymphocyte counts than young adult beagles

The effects of age on microbiota composition, gut fermentation end-product formation and peripheral lymphocyte numbers were compared between old and young adult Beagle dogs fed four kibble diets differing in yeast cell wall contents. The experiment had a double 4 x 4 Latin square design, one with four mature dogs (4 years old) and the other with four old dogs (10 years old), with four replicates (diets) per dog. In each period a 15d adaptation period preceded a 5d total collection of faeces for the digestibility trial. on day 21, fresh faecal samples were collected for the determination of bacterial enumeration, pH, biogenic amine and short-chain fatty acid. Flow cytometry was used for immunophenotypic evaluation. Dogs were fed four kibble diets with similar composition with 0, 0.15, 0.30 and 0.45% of yeast cell wall (as-fed), respectively. Data were evaluated using general linear models of Statistical Analysis Systems statistical software (P<0.05). No evidence of a difference in faecal bacteria counts between ages was found (total aerobes, total anaerobes, Bifidobacterium, Lactobacillus, Clostridium and Escherichia coli: P. 0.15). Faecal concentrations of butyrate, histamine, agmatine and spermine were lower (P <= 0.05) and faecal pH was higher (P=0.03) in older dogs than in mature adult dogs, suggesting an alteration in bacterial metabolic activity, or in the rate of intestinal absorption of these compounds. Concentrations of T-lymphocytes, T-cytotoxic lymphocytes and B-lymphocytes were also lower (P <= 0.01) in older dogs than in mature adult dogs. The study confirmed alterations in peripheral lymphocytes and revealed a reduced concentration of some fermentation end products in the colon of old dogs.

Periosteum-Derived Cells as an Alternative to Bone Marrow Cells for Bone Tissue Engineering Around Dental Implants. A Histomorphometric Study in Beagle Dogs

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Novel MesoPorous BioGlass/silk scaffold containing adPDGF-B and adBMP7 for the repair of periodontal defects in beagle dogs

AIM The local delivery of growth factors via gene therapy has gained tremendous awareness in recent years due to their sustained growth factor delivery to target tissues. The aim of this study was to fabricate and investigate a scaffold able to release growth factors via gene therapy for the repair of periodontal tissues. MATERIALS AND METHODS Novel mesoporous bioglass (MBG)/silk fibrin scaffold combined with BMP7 and/or PDGF-B adenovirus was fabricated and tested in vitro for cell migration, proliferation and differentiation. Furthermore, acute-type buccal dehiscence periodontal defects (mesiodistal width × depth: 5 × 5 mm) were created on the buccal portion of the maxillary premolars in five normal male beagle dogs (12 months old, 15.0 ± 2.0 kg) and histologically examined for periodontal regeneration following implantation of the following five groups: (1) no scaffold, (2) MBG/silk scaffold alone, (3) scaffold + adPDGF-B, (4) scaffold + adBMP7, (5) scaffold + adPDGF-b + adBMP7. RESULTS In vitro findings demonstrated that adPDGF-B was able to rapidly recruit periodontal ligament (PDL) cells over sixfold more effectively than adBMP7, whereas adBMP7 was more able to induce osteoblast differentiation of PDL cells. In vivo findings demonstrate that scaffolds loaded with adPDGF-B were able to partially regenerate the periodontal ligament while adBMP7 scaffolds primarily improved new bone formation. The combination of both adPDGF-B and adBMP7 synergistically promoted periodontal regeneration by allowing up to two times greater regeneration of the periodontal ligament, alveolar bone and cementum when compared to each adenovirus used alone. CONCLUSIONS Although both PDGF-B and BMP7 are individually capable of promoting periodontal regeneration to some degree, their combination synergistically promotes wound healing in acute-type buccal dehiscence periodontal defects when delivered simultaneously. This study demonstrates the promise for successful delivery of low-cost, effective growth factor delivery via gene therapy for the treatment of periodontal defects.

Evaluation of biomaterials with and without platelet-rich plasma: a histometric study using beagle dogs

Aim: To compare the alveolar bone repair process using biomaterial in dogs with and without the incorporation of platelet-rich plasma. Methods: Six beagles were used. Bilateral extractions of the three mandibular premolars were performed. Bio-Gen® was applied in the first alveolus, the clot was maintained in the second alveolus and Genox® was applied to the third alveolus. PRP was added to all alveoli on the left side only. The dogs were submitted to euthanasia after 30, 60 and 90 days and submitted to histological analysis for the determination of mean area of new bone formation. Tukey’s post test was used in the statistical analysis. Results: Significant increase in bone formation occurred in Bio-Gen® + PRP when compared with the other groups at 30 and 90 days. In the evaluation at 60 days, no statistically significant differences among the groups were found. Conclusions: The Bio-Gen® biomaterial led to the best bone repair and the combination of platelet-rich plasma accelerated the repair process.

Acellular dermal matrix as a barrier in guided bone regeneration: a clinical, radiographic and histomorphometric study in dogs

Objectives The purpose of this study was to evaluate the effectiveness of the acellular dermal matrix (ADM) as a membrane for guided bone regeneration (GBR), in comparison with a bioabsorbable membrane. Material and methods In seven dogs, the mandibular pre-molars were extracted. After 8 weeks, one bone defect was surgically created bilaterally and the GBR was performed. Each side was randomly assigned to the control group (CG: bioabsorbable membrane made of glycolide and lactide copolymer) or the test group (TG: ADM as a membrane). Immediately following GBR, standardized digital X-ray radiographs were taken, and were repeated at 8 and 16 weeks post-operatively. Before the GBR and euthanasia, clinical measurements of the width and thickness of the keratinized tissue (WKT and TKT, respectively) were performed. One animal was excluded from the study due to complications in the TG during wound healing; therefore, six dogs remained in the sample. The dogs were sacrificed 16 weeks following GBR, and a histomorphometric analysis was performed. Area measurements of new tissue and new bone, and linear measurements of bone height were performed. Results Post-operative healing of the CG was uneventful. In the TG membrane was exposed in two animals, and one of them was excluded from the sample. There were no statistically significant differences between the groups for any histomorphometric measurement. Clinically, both groups showed an increase in the TKT and a reduction in the WKT. Radiographically, an image suggestive of new bone formation could be observed in both groups at 8 and 16 weeks following GBR. Conclusion ADM acted as a barrier in GBR, with clinical, radiographic and histomorphometric results similar to those obtained with the bioabsorbable membrane. To cite this article:Borges GJ, Novaes AB Jr, de Moraes Grisi MF, Palioto DB, Taba M Jr, de Souza SLS. Acellular dermal matrix as a barrier in guided bone regeneration: a clinical, radiographic and histomorphometric study in dogs.Clin. Oral Impl. Res. 20, 2009; 1105-1115.

Digestibility and metabolizable energy of maize gluten feed for dogs as measured by two different techniques

Maize gluten feed (MGF) is a co-product of wet milling of maize, and is composed of structures that remain after most starch, gluten and germ has been extracted from the grain. Although currently used in dog foods, its digestibility and energy values have not been documented. Two techniques were used to determine nutrient digestibility of MGF for dog foods. Both techniques used extruded diets fed to Beagle dogs, with six replicates per diet. The first study used a difference method in which 300 g/kg of a reference diet was replaced by MGF. Based on the difference method, the coefficient of total tract apparent digestibility (CTTAD) of MGF was 0.53 for dry matter (DM), 0.69 for crude protein (CP), 0.74 for fat, 0.99 for starch, and 0.55 for gross energy (GE). The calculated metabolizable energy (ME) of MGF was 7.99 MJ/kg (as-fed). The second study used a regression method and included a basal diet and a basal diet with 70, 140 and 210 g MGF/kg of diet (as a substitute for maize starch). Maize gluten feed inclusion resulted in a linear reduction of CTTAD of DM (R(2)=0.99; P<0.001), CP (R(2)=0.95; P=0.002), fat (R(2)=0.87; P=0.009). starch (R(2)=0.81; P<0.001), and GE (R(2)=0.99; P<0.001). Faecal production increased linearly from 56 g to 107 g/dog/d (R(2)=0.99; P<0.001), with a linear reduction of faecal DM (R(2)=0.99: P<0.001) and a linear increase in faecal lactic acid concentration (P<0.02). Both urine (R(2)=0.77; P=0.029) and faeces (R(2)=0.92: P=0.019) showed a linear reduction in pH. Results of ingredient MAD obtained by the regression and difference methods were close (6% or less of variation) for CP, fat, and starch, and also for ME content (1.4% higher for the difference method), but the two methods disagreed on calculated CTTAD of DM and organic matter. The high dietary fiber content of MGF (382 g/kg) may explain the low digestibility of this ingredient. Maize gluten feed could be a useful ingredient for formulations designed to have low energy or reduce the urine pH of dogs. (C) 2011 Elsevier B.V. All rights reserved.

Faecal IgA concentration is influenced by age in dogs

Data comparing age-related alterations in faecal IgA concentrations of dogs are not available in the literature. The present study aimed to compare the faecal concentrations of IgA in puppies, mature and senior dogs. A total of twenty-four beagle dogs were used, including eight puppies (5 months old, four females and four males), eight mature (4.6 years old, eight males) and eight senior dogs (10.6 years old, three males and five females). Fresh faecal samples were collected from each dog for three consecutive days and pooled by animal. After saline extraction, IgA content was measured by ELISA. Data were analysed by one-way ANOVA, and means were compared with Tukey's test (P<0.05). Results showed that puppies have lower faecal IgA concentrations than mature dogs (P<0.05); senior animals presented intermediary results. The reduced faecal IgA concentration in puppies is consistent with the reduced serum and salivary IgA concentrations reported previously, suggesting a reduced mucosal immunity in this age group. Although some studies have found an increased serum IgA concentration in older dogs, this may differ from the intestinal secretion of IgA, which appears to be lower in some senior animals (four of the eight dogs studied).

The intravenous glucose tolerance and postprandial glucose tests may present different responses in the evaluation of obese dogs

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Gastric motility evaluated by electrogastrography and alternating current biosusceptometry in dogs

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Long-term accumulation and microdistribution of uranium in the bone and marrow of beagle dog

The accumulation and microdistribution of uranium in the bone and marrow of Beagle dogs were determined by both neutron activation and neutron-fission analysis. The experiment started immediately after the weaning period, lasting till maturity. Two animal groups were fed daily with uranyl nitrate at concentrations of 20 and 100 mug(-1) food. of the two measuring techniques, uranium accumulated along the marrow as much as in the bone, contrary to the results obtained with single, acute doses. The role played by this finding for the evaluation of radiobiological long-term risks is discussed. It was demonstrated, by means of a biokinetical approach, that the long-term accumulation of uranium in bone and marrow could be described by a piling up of single dose daily incorporation.