Effect of salivary stimulation on erosion of human and bovine enamel subjected or not to subsequent abrasion: An in situ/ex vivo study

This in situ/ex vivo study evaluated whether saliva stimulated by chewing gum could prevent or reduce the wear and the percent change in microhardness (%SMH) of bovine and human enamel submitted to erosion followed by brushing abrasion immediately or after 1 h. During 2 experimental 7-day crossover phases, 9 previously selected volunteers wore intraoral palatal devices, with 12 enamel specimens (6 human and 6 bovine). In the first phase, the volunteers immersed the device for 5 min in 150 ml of cola drink, 4 times per day (at 8, 12, 16 and 20 h). Immediately after the immersions, no treatment was performed in 4 specimens, 4 other specimens were immediately brushed (0 min) using a fluoride dentifrice, and the device was replaced into the mouth. After 60 min, the remaining 4 specimens were brushed. In the second phase, the procedures were repeated, but after the immersions, the volunteers stimulated the salivary flow rate by chewing a sugar-free gum for 30 min. Changes in wear and %SMH were measured. ANOVA and Tukey's test showed statistical differences (p < 0.05) for the following comparisons. The chewing gum promoted less wear and %SMH. A decreasing %SMH and an increasing enamel wear were observed in the following conditions: erosion only, 60 min and 0 min. The human enamel presented greater %SMH and less wear compared to bovine enamel. The data suggest that the salivary stimulation after an erosive or erosive/abrasive attack can reduce the dental wear and the %SMH.

Mineral intake independent from gastric irritation or pica by cell-dehydrated rats

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

Cytotoxic effects of permethrin in oocytes of Rhipicephalus sanguineus (Acari: Ixodidae) fully engorged females: I. Direct or indirect action of the acaricide in germ cells?

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

Does attraction to frugivores or defense against pathogens shape fruit pulp composition?

Fruit traits evolve in response to an evolutionary triad between plants, seed dispersers, and antagonists that consume fruits but do not disperse seeds. The defense trade-off hypothesis predicts that the composition of nutrients and of secondary compounds in fruit pulp is shaped by a trade-off between defense against antagonists and attraction to seed dispersers. The removal rate model of this hypothesis predicts a negative relationship between nutrients and secondary compounds, whereas the toxin-titration model predicts a positive relationship. To test these alternative models, we evaluated whether the contents of nutrients and secondary compounds can be used to predict fruit removal by mutualists and pathogens in 14 bird-dispersed plants on a subtropical island in São Paulo state, southeastern Brazil. We selected eight to ten individuals of each species and prevented fruit removal by covering four branches with a net and left fruits on four other branches available to both, vertebrate fruit consumers and pathogens. The persistence of ripe fruits was drastically different among species for bagged and open fruits, and all fruit species persisted longer when protected against seed dispersers. We found that those fruits that are quickly removed by vertebrates are nutrient-rich, but although the attack rate of pathogens is also high, these fruits have low contents of quantitative defenses such as tannins and phenols. Thus, we suggest that the fruit removal rate by seed dispersers is the primary factor selecting the levels of fruit defense. Likewise, nutrient-poor fruits have low removal of seed dispersers and low probability of attack by pathogens. These species retain ripe fruits in an intact condition for a prolonged period because they are highly defended by secondary compounds, which reduce overall attractiveness. However, this strategy might be advantageous for plants that depend on rare or unreliable dispersers.

Influence of Osteopenia in Autogenous Bone Graft Healing With or Without Expanded Polytetrafluoroethylene Membranes: Histologic and Histomorphometric Study in Rats

Purpose: The aim of this study was to quantitatively evaluate and qualitatively describe autogenous bone graft healing with or without an expanded polytetrafluoroethylene (e-PTFE) membrane in ovariectornized rats. Materials and Methods: Eighty Wistar rats, weighing approximately 300 g each, were used. A graft was obtained from the parietal bone and fixed to the sidewall of each animal's left mandibular ramus. The animals were randomly divided into four experimental groups (n = 20 in each group): group 1, sham operated and autogenous bone graft only- group 2, sham operated and autogenous bone graft covered by e-PTFE membrane; group 3, ovariectornized (OVX) and autogenous bone graft only- group 4, OVX and autogenous bone graft covered by e-PTFE membrane. The animals were sacrificed at five different time points: immediately after grafting or at 7, 21, 45, or 60 days after grafting. Histologic examination and morphometric measurement of the sections were performed, and values were submitted to statistical analyses. Results: Both groups (sham and OVX) experienced loss of the original graft volume when it was not covered by the membrane, whereas use of the membrane resulted in additional bone formation beyond the edges of the graft and under the membrane. Histologic analysis showed integration of the grafts in all animals, although a larger number of marrow spaces was found in OVX groups. Conclusions: Association of bone graft with an e-PTFE membrane resulted in maintenance of its original volume as well as formation of new bone that filled the space under the membrane. Osteopenia did not influence bone graft repair, regardless of whether or not it was associated with e-PTFE membrane, but descriptive histologic analysis showed larger numbers of marrow spaces in the bone graft and receptor bed and formation of new bone in the OVX animals. INT J ORAL MAXILLOFAC IMPLANTS 2009;24:1074-1082

Absence or weak correlation between chewing side preference and lateralities in primary, mixed and permanent dentition

Objectives: To determine whether chewing side preference (CSP) is correlated to lateralities (handedness, footedness, eyedness and earedness) in primary, mixed and permanent dentitions.Design: Three-hundred subjects were divided into 3 groups: Group 1-100 children 3-5 years old, primary dentition; Group 2-100 children 6-12 years old, mixed dentition; Group 3 - 100 subjects 18-47 years old, permanent dentition. CSP was determined using a method developed by Mc Donnell et al.(9) Subjects were given a piece of gum and the position of the chewing gum was recorded 7 times as right or left. Subjects were classified as 'observed preferred chewing side' (OPCS) when they performed 5/7, 6/7 or 7/7 strokes on the same side. OPCS corresponded to the CSP. Laterality tests were performed for handedness, footedness, eyedness and earedness tasks. The Chi-square (chi(2)) and phi correlation (r) tests were used to investigate significant correlations between CSP and sidedness.Results: There was a significant correlation between chewing and earedness (p = 0.00), although there was weak positive correlation (r = 0.30) for primary dentition. There were significant correlations between chewing and handedness (p = 0.02; r = 0.25) and chewing and footedness (p = 0.02; r = 0.26), however, there were weak positive correlations for mixed dentition; there were significant correlations between chewing and handedness (p = 0.02; r = 0.26); chewing and footedness (p = 0.00; r = 0.33) and chewing and earedness (p = 0.01; r = 0.29); however, there were weak positive correlations for permanent dentition.Conclusion: It may be concluded that CSP can be significantly correlated with: earedness for primary dentition; handedness and footedness for mixed dentition; handedness, footedness and earedness for permanent dentition, but these are weak positive relationships. Future work on larger samples of left- and right-sided individuals is required to validate the findings. (C) 2012 Elsevier Ltd. All rights reserved.

Late administration of a specific COX-2 inhibitor does not treat and/or prevent progression of gastric tumors in rats submitted to duodenogastric reflux procedure

PURPOSE:To assess whether late introduction of a specific COX-2 inhibitor (Meloxicam) can treat and/or prevent the progression of tumors in the stomach of rats submitted to duodenogastric reflux. METHODS: Seventy five male Wistar rats, weighing 150 grams, were submitted to the induction of duodenogastric reflux through the pylorus. At 36 weeks of follow-up were established three experimental groups: DGR36 sacrificed immediately, DGR54 and DGR54MLX both sacrificed at 54th week of follow-up . The animals of the latter group were fed with a rat chow premixed with Meloxicam (2.0 mg/ kg feed; 0.3 mg / kg bw / day) and the other two with standard rat chow. The lesions found in the pyloric mucosa and gastrojejunal anastomosis were analyzed macroscopically and histologically. For statistical analysis was adjusted a generalized linear model assuming a binomial distribution with LOGIT link function. RESULTS: No significant differences were found when comparing the incidences of benign tumor lesions (Adenomatous Hyperplasia), p=0.4915, or malignant (Mucinous Adenocarcinoma), p=0.2731, among groups. CONCLUSION: Late introduction of specific COX-2 inhibitor (Meloxicam) did not treat and was not able to prevent the progression of tumoral lesions induced by duodenogastric reflux in the rat stomachs.

Extinction of a conditioned response in rainbow trout selected for high or low responsiveness to stress

Two lines of rainbow trout (Oncorhynchus mykiss) that exhibit divergent endocrine responsiveness to stressors also display disparate behavioral traits. To investigate whether the high-responding (HR) and low-responding (LR) fish also differ in cognitive function, the rate of extinction of a conditioned response was compared between the two lines. Groups of HR and LR fish were exposed to a paired conditioned stimulus (CS- water off) and unconditioned stimulus (US; confinement stressor). After exposure to 18 CS-US pairings, at least 70% of individuals of both lines acquired a conditioned response (CR) manifested as an elevation of blood cortisol levels on presentation of the CS only. Post-conditioning, the fish were tested by presentation of the CS at weekly intervals, for 4 weeks, with no further reinforcement, and the extinction of the CR in the two lines was compared. The decline in mean plasma cortisol levels after exposure to the CS over successive tests suggested that the CR was retained for a shorter period among the HR (<14 days) than LR fish (<21 days). The frequency of individuals within each line whose plasma cortisol levels indicated a stress response when exposed to the CS was significantly greater among the LR than HR fish at 14 and 21 days with no HR fish falling into this category at 21 days. At 28 days post-conditioning, there were no HR fish and only three LR fish were categorized as stressed. These results suggest that there are differences in cognitive function between the two lines. Possible mechanisms underlying these differences are discussed. (C) 2004 Elsevier B.V. All rights reserved.

Idazoxan and the effect of intracerebroventricular oxytocin or vasopressin on sodium intake of sodium-depleted rats

The alpha(2)-adrenergic agonist clonidine and the neuropeptide oxytocin, inhibit sodium intake when injected intracerebroventricularly (i.c.v.). The present work investigates whether (1) vasopressin also inhibits sodium intake when injected i.c.v., and (2) the effect of oxytocin and of vasopressin on sodium intake is affected by i.c.v. injection of idazoxan, an alpha(2)-adrenergic antagonist. Clonidine (30 nmol), oxytocin (40, 80 nmol) and vasopressin (40, 80 nmol) were injected i.c.v. 20 min prior to a 1.5% NaCl appetite test, in rats depleted of sodium for 24 h by a combination of a single s.c. injection of furosemide (10 mg/rat) and removal of ambient sodium. Every dose of clonidine, oxytocin and vasopressin inhibited the 1.5% NaCl intake. Seizures were observed with the higher dose of vasopressin, but not with either dose of oxytocin. The effect of i.c.v. injection of clonidine (30 nmol), oxytocin (80 nmol) or vasopressin (40 nmol) was partially inhibited by prior i.c.v. injection of idazoxan (160, 320 nmol). The results suggest that the inhibition of 1.5% NaCl intake induced by i.c.v. injection of neuropeptides in sodium-depleted rats depends, in part, on the activation of central alpha(2)-adrenoceptors. (C) 1997 Elsevier B.V. B.V. All rights reserved.

Visual timing and adaptive behavior in a road-crossing simulation study

In this road-crossing simulation study, we assessed both participant's ability to visually judge whether or not they could cross a road, and their adaptive walking behavior. To this end, participants were presented with a road inside the laboratory on which a bike approached with different velocities from different distances. Eight children aged 5-7, ten children aged 10-12, and ten adults were asked both to verbally judge whether they could cross the road, and to actually walk across the road if possible. The results indicated that the verbal judgments were not similar to judgments to actually cross the road. With respect to safety and accuracy of judgments, groups did not differ from each other, although the youngest group tended to be more cautious. All groups appeared to use a strategy to cross the road based both on the distance and the velocity of the approaching bike. Young children waited longer on the curb before crossing the road than older children and adults. All groups adjusted their crossing time to the time-to-arrival of the bike. These findings are discussed in relation to the ecological psychological approach and the putative dissociation between vision for perception (i.e. verbal judgment) and vision for action (i.e. actual crossing). (c) 2004 Elsevier Ltd. All rights reserved.

Oxytocinergic and serotonergic systems involvement in sodium intake regulation: satiety or hypertonicity markers?

Previous studies demonstrated the inhibitory participation of serotonergic ( 5-HT) and oxytocinergic (OT) neurons on sodium appetite induced by peritoneal dialysis (PD) in rats. The activity of 5-HT neurons increases after PD- induced 2% NaCl intake and decreases after sodium depletion; however, the activity of the OT neurons appears only after PD-induced 2% NaCl intake. To discriminate whether the differential activations of the 5-HT and OT neurons in this model are a consequence of the sodium satiation process or are the result of stimulation caused by the entry to the body of a hypertonic sodium solution during sodium access, we analyzed the number of Fos-5-HT- and Fos-OT-immunoreactive neurons in the dorsal raphe nucleus and the paraventricular nucleus of the hypothalamus-supraoptic nucleus, respectively, after isotonic vs. hypertonic NaCl intake induced by PD. We also studied the OT plasma levels after PD- induced isotonic or hypertonic NaCl intake. Sodium intake induced by PD significantly increased the number of Fos-5- HT cells, independently of the concentration of NaCl consumed. In contrast, the number of Fos-OT neurons increased after hypertonic NaCl intake, in both depleted and nondepleted animals. The OT plasma levels significantly increased only in the PD- induced 2% NaCl intake group in relation to others, showing a synergic effect of both factors. In summary, 5-HT neurons were activated after body sodium status was reestablished, suggesting that this system is activated under conditions of satiety. In terms of the OT system, both OT neural activity and OT plasma levels were increased by the entry of hypertonic NaCl solution during sodium consumption, suggesting that this system is involved in the processing of hyperosmotic signals.

The relationship of oral malodor in patients with or without periodontal disease

Background: Halitosis has been correlated with the concentration of volatile sulfur compounds (VSC) produced in the oral cavity by metabolic activity of bacteria colonizing the periodontal area and the dorsum of the tongue. The aim of this study was to determine whether there is some relationship between the presence of N-benzoyl-DL-arginine-2-napthylamide (BANA)positive species Treponema denticola, Porphyromonas gingivalis, and Bacteroides forsythus and clinical and oral malodor parameters.Methods: Twenty-one subjects (21 to 59 years old) with probing depths (PD) >3.0 mm and 20 subjects (21 to 63 years old) with PD less than or equal to3.0 mm (controls) participated. The quality of the mouth air was assessed organoleptically, and a portable sulfide monitor was used to measure the concentration of VSC. Clinical parameters, plaque index (PI) and gingival index (GI), were obtained from 6 teeth. Samples for BANA test were taken from the dorsal surface of the tongue, saliva, and the 6 reference teeth.Results: the scores of PI, GI, subgingival samples that tested positive for BANA hydrolyzing species, organoleptic ratings, and VSC values were significantly higher in the subjects with PD >3.0 mm (P <0.01, Mann-Whitney U test). There was a correlation between BANA hydrolysis by subgingival plaque bacteria and VSC values (r = 0.55, P <0.01), and between GI and VSC values (r = 0.48, P <0.05) in patients with PD >3.0 mm. There was no significant correlation between these parameters in the control group.Conclusion: These results confirm that the BANA hydrolyzing bacteria in the subgingival plaque are an important source of malodor production in the oral cavity.

Safety in road crossing of children with cerebral palsy

Aim: Children with cerebral palsy (CP) are regularly confronted with physical constraints during locomotion. Because abnormalities in motor control are often related to perceptual deficits, the aim of this study was to find out whether children with CP were able to walk across a road as safely as their non-handicapped peers. Method: Ten children with CP and 10 non-handicapped children aged 4-14 y were asked to cross a simulated road if they felt the situation was safe. Results: With respect to safety and accuracy of crossings, the behaviour of children with CP was comparable with that of non-handicapped children. However, a closer examination of children's individual crossing behaviour showed considerable differences within the CP group. In contrast to children with damage to the left hemisphere, children with damage to the right hemisphere made unsafe decisions and did not compensate for them by increasing walking speed.Conclusion: the differences in unsafe behaviour and in the ability to compensate for it within the group of children with CP might be related to damage to specific regions of the brain that are involved in the processing of spatial or temporal information.

Differential response of the luteal phase and fertility in cattle following ovulation of the first-wave follicle with human chorionic gonadotropin or an agonist of gonadotropin-releasing hormone

A series of experiments with Holstein heifers was conducted to develop the capability of inducing accessory corpus luteum (CL) with a GnRH agonist (Buserelin, 8 mu g; GnRHa) or hCG; (3,000 IU) to increase plasma progesterone concentrations (Exp. 1, 2, and 3) and to test whether induction of accessory CL with hCG will increase conception rates in heifers (Exp. 4) and lactating cows (Exp. 5). In Exp. 1, heifers were treated on d 5 after estrus with GnRHa (n = 8) or saline (n = 7); heifers in Exp. 2 received hCG (n = 5) or saline (n = 4) on d 5. Experiment 3 allowed a contemporary evaluation of heifers treated on d 5 with GnRHa (n = 6), hCG (n = 6), saline (n = 6), or GnRHa at d 5 and hCG at the time of the induced ovulation (n = 5). The GnRHa and hCG were equally effective in inducing an accessory CL (93% induction rate), but the subsequent increase in progesterone concentrations was greater in hCG-treated heifers. A greater half life of hCG may provide longer LH-like stimulation of the first-wave follicle and subsequent developing accessory CL or a greater luteotropic effect on the original CL. Induction of an accessory CL with hCG on d 5 or 6 after insemination did not increase pregnancy rates in fertile heifers (Exp. 4: hCG = 64.8% vs control = 62.9%; n = 243) or lactating dairy cows during summer heat stress (Exp. 5: hCG = 24.2% vs control = 23.5%; n = 201).

Effect of an iron mouthrinse on enamel and dentine erosion subjected or not to abrasion: An in situ/ex vivo study

Objectives: This in situ/ex vivo study evaluated whether a rinse with an iron solution could reduce wear and the percentage of microhardness change of human enamel and dentine submitted to erosion followed by brushing after 1 or 30 min.Design: During 2 experimental 5-day crossover phases (wash-out period of 10 days), 10 volunteers wore intraoral palatal devices, with 12 specimens (6 of enamel and 6 of dentine) arranged in 3 horizontal rows (4 specimens each). In one phase, the volunteers immersed the device for 5 min in 150 mL of cola drink, 4 times a day. Immediately after immersion, no treatment was performed in one row. The other row was brushed after 1 min using a fluoride dentifrice and the device was replaced into mouth. After 30 min, the remaining row was brushed. In the other phase, the procedures were repeated, but after immersion the volunteers rinsed for 1 min with 10 mL of a 10 mM ferrous sulphate solution. Changes in surface microhardness (%SMH) and wear (profilometry) of enamel and dentine were measured. Data were tested using ANOVA and Tukey's tests (p < 0.05).Results: the enamel presented more wear than dentine, under all experimental conditions. The iron solution caused a significant reduction on the %SMH in enamel, and a significant reduction on the wear in dentine, regardless the other conditions.Conclusions: Rinsing with an iron solution after an erosive attack, followed or not by an abrasive episode, may be a viable alternative to reduce the loss of dental structure. (c) 2006 Elsevier Ltd. All rights reserved.