Mechanical behavior of prosthesis in Toucan beak (Ramphastos toco)

The purpose of this study is to characterize the structure of the beak of Toco Toucan (Ramphastos toco) and to investigate means for arresting fractures in the rhinotheca using acrylic resin. The structure of the rhamphastid bill has been described as a sandwich structured composite having a thin exterior comprised of keratin and a thick foam core constructed of mineralized collagenous rods (trabeculae). The keratinous rhamphotheca consists of superposed polygonal scales (approximately 50 pm in diameter and 1 mu m in thickness). In order to simulate the orientation of loading to which the beak is subjected during exertion of bite force, for example, we conducted flexure tests on the dorso-ventral axis of the maxilla. The initially intact (without induced fracture) beak fractured in the central portion when subjected to a force of 270 N, at a displacement of 23 mm. The location of this fracture served as a reference for the fractures induced in other beaks tested. The second beak was fractured and repaired by applying resin on both lateral surfaces. The repaired maxilla sustained a force of 70 N with 6.5 mm deflection. The third maxilla was repaired similarly except that it was conditioned in acid for 60s prior to fixation with resin. It resisted a force of up to 63 N at 6 mm of deflection. The experimental results were compared with finite element calculations for unfractured beak in bending configuration. The repaired specimens were found to have strength equal to only one third of the intact beak. Finite element simulations allow visualization of how the beak system (sandwich shell and cellular core) sustains high flexural strength. (C) 2010 Elsevier B.V. All rights reserved.

Food aversion: A critical balance between allergen-specific IgE levels and taste preference

Animals sensitized to allergens change their feeding behavior and avoid drinking the otherwise preferred sweetened solutions containing the allergens. This phenomenon, known as food aversion, appears to be mediated by allergen-specific IgE antibodies. Here we investigated food aversion in BALB/c and C57BL/6 mice, which differ in their allergic responses to the allergen ovalbumin as well as in their preference for sweet taste. BALB/c mice present higher levels of IgE and a natural lower preference for sweet flavors when compared to C57BL/6 mice. Specifically, we studied a conflicting situation in which animals simultaneously experienced the aversive contact with the allergen and the attractive sweet taste of increasing concentrations of sucrose. We found that BALB/c mice were more prone to develop food aversion than C57BL/6 mice and that this aversive behavior could be abolished in both strains by increasing the palatability of the solution containing the allergen. In both strains food aversion was positively correlated with the levels of allergen-specific IgE antibodies and inversely correlated with their preference for sucrose sweetened solutions. (C) 2009 Elsevier Inc. All rights reserved.

Prenatal Lipopolysaccharide Reduces Social Behavior in Male Offspring

Objective: This study investigated the relationship between maternal sickness behavior during pregnancy and offspring development and behavior. Methods: Pregnant Wistar rats were administered with lipopolysaccharide (LPS, 100 mu g/kg, i.p.) on gestation day (GD) 9.5. Dams` sickness behavior was analyzed, and at birth, offspring number and weight were evaluated. Male offspring was evaluated through physical development, play behavior, adult social interaction, plus maze studies and morphological analysis of the brain. Results: Results, with respect to the control group, showed that: (1) LPS decreased general activity, food intake, and weight gain in dams, but no pyrexia was observed following treatment; (2) LPS reduced litter size, but no alterations in physical development were observed; (3) LPS reduced play behavior parameters in baby rats; (4) LPS decreased adult social interaction; (5) no alterations were observed between groups on plus maze studies; (6) no differences were observed between groups on morphological analyses of the brain. Conclusion: These data reveal that LPS administered on GD 9.5 impaired male offspring`s social behavior in infancy and adulthood. These results may be related to an alteration in motivational states or/and increased anxiety. Copyright (C) 2010 S. Karger AG, Basel

Prenatal Lipopolysaccharide Exposure Affects Maternal Behavior and Male Offspring Sexual Behavior in Adulthood

Objective: This study investigates the effects of prenatal lipopolysaccharide (LPS) exposure on the maternal behavior of pregnant rats and the physical development and sexual behavior of their male offspring in adulthood. Methods: For two experiments, pregnant rats were injected with LPS (250 mu g/kg, i.p.) on gestation day (GD) 21. In the first experiment, the maternal behavior (postnatal day, PND, 6) and the dam`s open-field general activity (PND7) were evaluated. In the second experiment, the maternal pre- and postnatal parameters, the pup`s development, the offspring`s sexual behavior in adulthood, and the pup`s organ weights were assessed. Results: Compared to the control group, the LPS-treated dams presented reduced maternal behavior, decreased general activity, a smaller body weight difference between GD21 and PND1, a greater number of perinatal deaths, and smaller litters. For the male pups, LPS treatment resulted in a decreased body weight on PND2, whereas the anogenital distance and the day of testis descent were not modified. The male sexual behavior was impaired by prenatal LPS. Particularly the number of ejaculating animals was reduced. The testis weight was also lower in the prenatally LPS-treated rats than in the control rats. Conclusion: We propose that prenatal LPS exposure on GD21 acts as an imprinting factor that interferes with the programming of brain sexual determination in offspring. Copyright (C) 2009 S. Karger AG, Basel

Sickness and Aggressive Behavior in Dominant and Subordinate Mice

Sick animals show a set of organized behavioral changes (sickness behavior), which is the result of a motivational re-organization of the behavior as a whole. Sickness behavior display can be influenced by the social context. In this work, we sought to investigate the regulation of sickness behavior within a pair of mice in the presence of an intruder mouse. Dominant and subordinate mice were treated with the bacterial endotoxin lipopolysaccharide (LPS) and were challenged with the presence of an intruder mouse. LPS effects depended on ranking and social context. Even though dominant mice displayed more agonistic interaction towards the intruder, subordinate mice displayed agonistic behavior towards the intruder when their dominant companion was treated with LPS. The results show that, not only sickness behavior is differentially expressed among different social ranks, but also that sickness behavior is related to different reactions among surrounding animals. These data are relevant for a biological approach to the relation between sickness behavior and social behavior.

Ivermectin impairs sexual behavior in sexually naive, but not sexually experienced male rats

Ivermectin (IVM) is an antiparasitic drug, widely used in domestic animals. In mammals, IVM act as a GABA agonist. This neurotransmitter has an important role in the regulation of sexual behavior. Thus, this study sought to investigate the effects of various medically relevant doses IVM on the sexual behavior of male rats. In particular, we also wished to examine if previous sexual experience modulated responses to IVM. In the first experiment, the sexual behavior of inexperienced male rats was analyzed after they received 0.2, 0.6, 1.0 or 2.0 mg/kg IVM, 15 mm prior to behavioral testing. In the second experiment, the effects of four previous sexual experiences on IVM treated rats (1.0 or 2.0 mg/kg, 15 min prior to the 5th session) were assessed. The standard therapeutic dose (0.2 mg/kg) did not impair the sexual behavior of inexperienced male rats. At a more concentrated dose (0.6 mg/kg), which is still within the therapeutic range, the appetitive phase of sexual behavior of inexperienced male rats was impaired. Likewise, 1.0 mg/kg impaired the appetitive phase. Previous sexual experience blocked almost entirely this sexual impairment, suggesting that previous sexual experience exerts a positive effect in attenuating the sexual impairment produced by IVM treatment. Therefore, the standard therapeutic dose of IVM can be used without producing side effects on sexual behavior. Use of more concentrated therapeutic doses is not recommended during reproductive periods, unless the animals have had previous sexual experience. (C) 2010 Elsevier Ltd. All rights reserved.

Behavior: A Relevant Tool for Brain-immune System Interaction Studies

Neuroimmunomodulation describes the field focused on understanding the mechanisms by which the central nervous system interacts with the immune system, potentially leading to changes in animal behavior. Nonetheless, not many articles dealing with neuroimmunomodulation employ behavior as an analytical endpoint. Even fewer papers deal with social status as a possible modifier of neuroimmune phenomena. In the described sets of experiments, we tackle both, using a paradigm of social dominance and subordination. We first review data on the effects of different ranks within a stable hierarchical relationship. Submissive mice in this condition display more anxiety-like behaviors, have decreased innate immunity, and show a decreased resistance to implantation and development of melanoma metastases in their lungs. This suggests that even in a stable, social, hierarchical rank, submissive animals may be subjected to higher levels of stress, with putative biological relevance to host susceptibility to disease. Second, we review data on how dominant and submissive mice respond differentially to lipopolysaccharide (LPS), employing a motivational perspective to sickness behavior. Dominant animals display decreased number and frequency in several aspects of behavior, particularly agonistic social interaction, that is, directed toward the submissive cage mate. This was not observed in submissive mice that maintained the required behavior expected by its dominant mate. Expression of sickness behavior relies on motivational reorganization of priorities, which are different along different social ranks, leading to diverse outcomes. We suggest that in vitro assessment of neuroimmune phenomena can only be understood based on the behavioral context in which they occur.

Effects of individual housing on behavior and resistance to Ehrlich tumor growth in mice

This study analyzed in Balb/C mice the effects of individual housing on behavior, serum corticosterone and resistance to Ehrlich tumor growth. Mice (60 days old) were individually (IH) or grouped housed (G) (10-12 animals/cage) for 14-21 days. The 1st day of the housing condition was considered experimental day 1 (ED1). Results showed that on ED21, IH mice, when compared to G mice, presented no differences on corticosterone serum levels when kept undisturbed; however, an increased level of this hormone was observed in IH mice after an immobilization stress challenge. An increased time spent in the plus-maze closed arms and a decreased time in the open arms were also observed in IH mice. When compared to G animals, after inoculation with 105 Ehrlich tumor cells on ED1, IH mice presented an increase in volume of ascitic fluid and number of tumor cells. The survival time of IH mice was also shorter than that measured in G animals. Furthermore, IH mice injected with a different number of tumor cells on ED1 always presented increased Ehrlich tumor cells than G group. Interestingly. these effects were not observed when the tumor cells injection was done on ED4. These results suggest that individual-housing conditions induce an altered immune-endocrine response and, at the same time, decrease animals` resistance to Ehrlich tumor growth. It is proposed that the neural link between the behavioral and immunological changes observed after the stress of individual housing might involve the activation of the HPA axis. (C) 2008 Elsevier Inc. All rights reserved.

Effects of Prepartum Ingestion of Ipomoea carnea on Postpartum Maternal and Neonate Behavior in Goats

Ipomoea carnea is a toxic plant that grows in tropical areas, and is readily consumed by grazing goats. The plant contains the alkaloids swainsonine and calystegines, which inhibit cellular enzymes and cause systematic cell death. This study evaluated the behavioral effects on dams and kids of prenatal ingestion of this plant. Freshly harvested leaves of I. carnea (10 g/kg body weight) were fed daily to nine pregnant goats from the fifth to the 16th week of gestation; five pregnant goats were controls. Dam and kid behavior were evaluated during 2-hr postpartum. Further evaluation of the offspring was performed using various tests after birth: (1) reaching and discriminating their dam from an alien doe (two tests at 12-hr postpartum), and (2) navigating a progressive maze (2, 4, and 6 days postpartum). Postnatal (n=2) and fetal (n=2) mortality were observed in the treated group. Intoxicated kids had difficulty in standing at birth, and only one was able to suckle within 2 hr of birth. Treated kids were slower than controls to arrive at their dam in the discrimination test; treated kids often (seven of nine completed tests) incorrectly chose the alien dam (controls: 0/10 tests). During some runs on days 2, 4, and 6 postpartum, treated kids were slower to leave the starting point of the maze, and were slower to arrive at the dam on all test days. This study suggests that the offspring of pregnant goats given I. carnea during gestation have significant behavioral alterations and developmental delays. Birth Defects Res (Part B) 92:131-138, 2011. (C) 2011 Wiley-Liss, Inc.

In vitro chemosensitivity of canine mast cell tumors grades II and III to all-trans-retinoic acid (ATRA).

Mast cell tumor (MCT) is one of the most prevalent neoplasms that affect the skin and soft tissue of dogs. Because mast cell tumors present a great variety of clinical appearance and behavior, their treatment becomes a challenge. While retinoids are well recognized as promising antitumor agents, there have been only a few reports about retinoids` effect on canine cancers. The aim of this study was to investigate the chemosensitivity of MCT grades II and III to all-trans retinoic acid (ATRA). Immediately after surgical resection, MCT were prepared for primary culture. Samples of MCTs were also fixed in formalin for histopathology and grading according to the classification of Patnaik et al. (Veterinary Pathology 21(5):469-474, 1984). The best results were obtained when neoplastic mast cells were co-cultivated with fibroblasts. Cultured mast cells were, then, treated with concentrations of 10(-4) to 10(-7) M of ATRA, in order to evaluate their chemosensitivity to this retinoid. MTT assay was performed to estimate cell growth and death. The highest level of mast cell chemosensivity was obtained at the dose of 10(-4) M (p < 0,002). MCT of grades II or III were equally susceptible to the treatment with ATRA. Cell death was observed on the first 24 h until 48 h. According to these results, ATRA may be a potential chemotherapeutic agent for the treatment of canine MCT.

Downregulation of CD9 protein expression is associated with aggressive behavior of oral squamous cell carcinoma

Squamous cell carcinoma of the oral cavity (OSCC) is a malignancy characterized by a high degree of local aggression and metastasis to cervical lymph nodes. Tetraspanins are proteins with functional roles in a wide array of cellular processes and are reported to be associated with tumor progression. The present study investigated the expression of the CD9, CD37, CD63, CD81 and CD82 tetraspanins in OSCC using immunohistochemistry (IHC) and quantitative Real Time-PCR (qRT-PCR). Tissue microarray (TMA) analysis of samples from 179 cases of OSCC and 10 normal samples oral mucosa were evaluated immunomorphologically. We analyzed CD9 and CD82 expression by qRT-PCR in 66 OSCC cases and 4 normal samples of oral mucosa. Expression of CD63, CD37 and CD81 was not detected in the samples studied. CD82 was downregulated or negative in 127 of 179 (80%) specimens; no correlation was observed between CD82 expression, clinicopathological parameters, disease-free survival and 5-year overall survival. CD9 expression was downregulated or negative in 75 of 129 (42%) OSCC samples. Loss of CD9 expression in OSCC samples correlated with the incidence of lymph node metastasis (p = 0.017). Disease-free survival and the 5-year overall survival of patients with downregulated or negative CD9 expression were significantly lower than in patients with positive CD9 expression (p = 0.010 and p = 0.071, respectively). No correlation was found between CD9 or CD82 expression and clinicopathological parameters by qRT-PCR. Our results suggest that the downregulation or lack of expression of the CD9 protein might indicate a more aggressive of OSCC. (C) 2009 Elsevier Ltd. All rights reserved.

Clear cell odontogenic carcinoma: case report with immunohistochemical findings adding support to the challenging diagnosis

Clear cell odontogenic carcinoma (CCOC) is a rare odontogenic tumor associated with aggressive clinical behavior, metastasis, and low survival. We report a case of CCOC affecting the mandible of a 39-year-old man. The tumor presented a biphasic pattern composed of clear cell nests intermingled with eosinophilic cells and separated by collagenous stroma. Immunoreactivity to cytokeratin (CK), specifically AE1/AE3 and CK 8, 14, 18, and 19 was found, as well as to epithelial membrane antigen (EMA). The tumor cells were negative for S100 protein, CK 13, vimentin, smooth muscle actin, laminin and type IV collagen. Low labeling indices for the proliferation markers Ki-67 and proliferating cell nuclear antigen and to p53 protein might predict a favorable prognosis for the lesion. A surgical resection was performed, followed by adjuvant radiotherapy. A 2-year follow-up has shown no signs of recurrence. The significance of histochemical and immunohistochemical resources in the correct diagnosis of CCOC is analyzed.

Slow crack growth and reliability of dental ceramics

Objective. To determine the slow crack growth (SCG) and Weibull parameters of five dental ceramics: a vitreous porcelain (V), a leucite-based porcelain (D), a leucite-based glass-ceramic (E1), a lithium disilicate glass-ceramic (E2) and a glass-infiltrated alumina composite (IC). Methods. Eighty disks (empty set 12mm x 1.1mm thick) of each material were constructed according to manufacturers` recommendations and polished. The stress corrosion susceptibility coefficient (n) was obtained by dynamic fatigue test, and specimens were tested in biaxial flexure at five stress rates immersed in artificial saliva at 37 degrees C. Weibull parameters were calculated for the 30 specimens tested at 1MPa/s in artificial saliva at 37 degrees C. The 80 specimens were distributed as follows: 10 for each stress rate (10(-2), 10(-1), 10(1), 10(2) MPa/s), 10 for inert strength (10(2) MPa/s, silicon oil) and 30 for 10(0) MPa/s. Fractographic analysis was also performed to investigate the fracture origin. Results. E2 showed the lowest slow crack growth susceptibility coefficient (17.2), followed by D (20.4) and V (26.3). E1 and IC presented the highest n values (30.1 and 31.1, respectively). Porcelain V presented the lowest Weibull modulus (5.2). All other materials showed similar Weibull modulus values, ranging from 9.4 to 11.7. Fractographic analysis indicated that for porcelain D, glass-ceramics E1 and E2, and composite IC crack deflection was the main toughening mechanism. Significance. This study provides a detailed microstructural and slow crack growth characterization of widely used dental ceramics. This is important from a clinical standpoint to assist the clinician in choosing the best ceramic material for each situation as well as predicting its clinical longevity. It also can be helpful in developing new materials for dental prostheses. (c) 2010 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Effect of ion exchange on R-curve behavior of a dental porcelain

The objective of this study was to evaluate the effect of the ion exchange treatment on the R-curve behavior of a leucite-reinforced dental porcelain, testing the hypothesis that the ion exchange is able to improve the R-curve behavior of the porcelain studied. Porcelain disks were sintered, finely polished, and submitted to an ion exchange treatment with a KNO(3) paste. The R-curve behavior was assessed by fracturing the specimens in a biaxial flexure design after making Vickers indentations in the center of the polished surface with loads of 1.8, 3.1, 4.9, 9.8, 31.4, and 49.0 N. The results showed that the ion exchange process resulted in significant improvements in terms of fracture toughness and flexural strength as compared to the untreated material. Nevertheless, the rising R-curve behavior previously observed in the control group disappeared after the ion exchange treatment, i.e., fracture toughness did not increase with the increase in crack size for the treated group.

Effect of processing induced particle alignment on the fracture toughness and fracture behavior of multiphase dental ceramics

Objective. To investigate the processing induced particle alignment on fracture behavior of four multiphase dental ceramics (one porcelain, two glass-ceramics and a glass-infiltrated-alumina composite). Methods. Disks (empty set12mm x 1.1 mm-thick) and bars (3 mm x 4 mm x 20 mm) of each material were processed according to manufacturer instructions, machined and polished. Fracture toughness (K(IC)) was determined by the indentation strength method using 3-point bending and biaxial flexure fixtures for the fracture of bars and disks, respectively. Microstructural and fractographic analyses were performed with scanning electron microscopy, energy dispersive spectroscopy and X-ray diffraction. Results. The isotropic microstructure of the porcelain and the leucite-based glass-ceramic resulted in similar fracture toughness values regardless of the specimen geometry. On the other hand, materials containing second-phase particles with high aspect ratio (lithium disilicate glass-ceramic and glass-infiltrated-alumina composite) showed lower fracture toughness for disk specimens compared to bars. For the lithium disilicate glass-ceramic disks, it was demonstrated that the occurrence of particle alignment during the heat-pressing procedure resulted in an unfavorable pattern that created weak microstructural paths during the biaxial test. For the glass-infiltrated-alumina composite, the microstructural analysis showed that the large alumina platelets tended to align their large surfaces perpendicularly to the direction of particle deposition during slip casting of green preforms. Significance. The fracture toughness of dental ceramics with anisotropic microstructure should be determined by means of biaxial testing, since it results in lower values. (C) 2009 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.