This book explores whether the world economy is breaking up into regional trading and currency blocs centred on the European Community, Japan and the United States. Frankel uses trade, investment and financial data to assess this issue. He concludes with an analysis of how trends in regional economic integration can be used as building blocks for a stronger multilateral system.

Regional Trading Blocs in the world economic system, reseñado por Antonio Ortiz-Mena L.N.

Therefore, the seeker after the truth is not one who studies the writings of the ancients and, following his natural disposition, puts his trust in them, but rather the one who suspects his faith in them and questions what he gathers from them, the one who submits to argument and demonstration, and not to the sayings of a human being whose nature is fraught with all kinds of imperfection and de‹ciency. Thus the duty of the man who investigates the writings of scientists, if learning the truth is his goal, is to make himself the enemy of all that he reads, and, applying his mind to the core and margins of its content, attack it from every side. He should also suspect himself as he performs his critical examination of it, so that he may avoid falling into either prejudice or leniency. (Ibn al-Haytham)1

국제정치이론 = Theory of international politics

Nonsteroidal anti-inflammatory drugs (NSAIDs) play an essential part in our approach to control pain in the posttraumatic setting. Over the last decades, several studies suggested that NSAIDs interfere with bone healing while others contradict these findings. Although their analgesic potency is well proven, clinicians remain puzzled over the potential safety issues. We have systematically reviewed the available literature, analyzing and presenting the available in vitro animal and clinical studies on this field. Our comprehensive review reveals the great diversity of the presented data in all groups of studies. Animal and in vitro studies present so conflicting data that even studies with identical parameters have opposing results. Basic science research defining the exact mechanism with which NSAIDs could interfere with bone cells and also the conduction of well-randomized prospective clinical trials are warranted. In the absence of robust clinical or scientific evidence, clinicians should treat NSAIDs as a risk factor for bone healing impairment, and their administration should be avoided in high-risk patients.

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Do Nonsteroidal Anti-Inflammatory Drugs Affect Bone Healing? A Critical Analysis

Osteocytes, the most abundant cells in bone, have been long postulated to detect and respond to mechanical and hormonal stimuli and to coordinate the function of osteoblasts and osteoclasts. The discovery that the inhibitor of bone formation sclerostin is primarily expressed in osteocytes in bone and downregulated by anabolic stimuli provided a mechanism by which osteocytes influence the activity of osteoblasts. Advances of the last few years provided experimental evidence demonstrating that osteocytes also participate in the recruitment of osteoclasts and the initiation of bone remodeling. Apoptotic osteocytes trigger yet-to-be-identified signals that attract osteoclast precursors to specific areas of bone, which in turn differentiate to mature, bone-resorbing osteoclasts. Osteocytes are also the source of molecules that regulate the generation and activity of osteoclasts, such as OPG and RANKL; and genetic manipulations of the mouse genome leading to loss or gain of function or to altered expression of either molecule in osteocytes markedly affect bone resorption. This review highlights these investigations and discusses how the novel concept of osteocyte-driven bone resorption and formation impacts our understanding of the mechanisms by which current therapies control bone remodeling.

Osteocyte-Driven Bone Remodeling

Dental implants in the medically compromised patient.

The purpose of this study was to evaluate the influence of ketoprofen on bone repair process in tibiae of rats by means of analysis of the digital optical density. Twenty Wistar rats were assigned to two groups: an untreated control group and a group treated with ketoprofen. The experimental procedures comprised the following stages: general anesthesia, preparation of a unicortical bone defect on the left tibia of each rat, medication with ketoprofen and radiographic examination. Digital radiographic images were acquired using Visualix GX-S-HDI digital sensor and an x-ray equipment. Radiographs were taken at baseline, 7, 14, 21 and 30 days postoperatively and the optical density (OD) was evaluated using the Vix win 1.4 system. The mean values of OD readings were analyzed statistically by ANOVA and Tukey's test with significance level set at a=5%. The control group showed a statistically significant correlation (p=0.001) between time and optical density, while the ketoprofen group exhibited a weak and not statistically significant correlation (p=0.100). The control group presented the smallest OD ratios at days 1 and 7, and the greatest OD ratios at days 14, 21 and 30, with statistically significant difference (p=0.001). There was no significant differences (p=0.100) among the OD ratios in the ketoprofen group, regardless of the evaluation period. The findings of this study suggest that ketoprofen influenced bone repair process because there was an increase in optical density during the first week and delayed new bone formation after the 21st day.

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Evaluation of digital optical density of bone repair in rats medicated with ketoprofen

This study aimed at morphometrically evaluating the influence of variable caloric values of ethanol consumption on alveolar bone loss in periodontitis in male rats. Thirty-six male rats were randomized into four groups of nine rats each, as follows: Test group A (low) - rats were fed an ethanol-containing liquid diet (ethanol representing 22% of total caloric value); Control group A -rats were fed a pair-fed control diet (ethanol replaced by isocaloric amounts of carbohydrate); Test group B (high) -rats were fed an ethanol-containing liquid diet (ethanol representing 36% of total caloric value); Control group B -rats were fed a pair-fed control diet for Test B. Following anesthesia, cotton ligatures were placed around the cervix of the right upper second molar. At eight weeks, the maxillary bones were removed and alveolar bone loss was analyzed by measuring the distance between the cementoenamel junction and the alveolar bone crest at buccal and palatal sites of the upper second molar. The unligated groups showed no significant differences between the bone loss values observed for the low and high caloric values of ethanol (p > 0.05). In the ligated groups, the rats receiving low caloric values of ethanol showed significantly greater bone loss compared to the isocaloric rats (p < 0.05); however, the rats receiving high caloric values of ethanol showed no significant differences compared to the controls. Analysis of the results demonstrated that, in male rats, ethanol itself affected ligature-induced bone loss when representing a low value in the total caloric value.

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Low caloric value of ethanol itself increases alveolar bone loss in ligature-induced periodontitis in male rats

This study analysed the initial effects of the combination of oestrogen deficiency with a calcium-deficient diet on alveolar bone repair. Sixty-three 3-month-old female rats were either ovariectomized (OVX, n = 42) or sham-operated (SHAM, n = 21). Among the 42 ovariectomized rats, 21 received standard commercial food (OVX) and 21 received food with low calcium content (ESP). The mandibular first molars were extracted bilaterally 15 days after ovariectomy or sham surgery. The rats were weighed and killed at 7, 21 and 45 days after tooth extraction. The results were evaluated by descriptive microscopic analysis, histomorphometry of the trabecular and osteoid volume and mast cell counts. Analysis of the results indicated that trabecular volume and mast cell counts increased significantly over time, while osteoid volume decreased over time. Comparisons between the SHAM and OVX groups demonstrated no statistical differences, while comparison between the OVX and ESP groups indicated differences in trabecular volume and the number of mast cells. The data suggest that hormonal deficiency does not delay alveolar bone repair in OVX rats; however, oestrogen deficiency associated with calcium deficiency can lead to bone resorption through the activation of mast cells.

Effects of experimental osteoporosis and low calcium intake on postextraction sockets of rats.

OBJECTIVE: The present study evaluated morphometrically bone loss percentages in experimental periodontitis in rats, comparing different locations (lingual mandible, palatal maxilla and buccal maxilla) and two evaluation methods (distance and area methods). MATERIAL AND METHODS: Ligatures were placed around the maxillary right second molar and around the mandibular right first molar in 14 female Wistar rats. The contralateral molars served as intragroup controls. After 4 weeks, the rats were sacrificed and their mandible and maxilla were removed. The specimens were dissected and stained with methylene blue dye. Bone loss was evaluated by two different methods on the surfaces of the defleshed jaw. In the first method, the distance from the cementoenamel junction (CEJ) to the alveolar bone crest was measured in the roots of teeth associated with ligature. In the second method, the area of bone loss was determined using the alveolar tissue bone, CEJ and the proximal region of roots associated with the ligature as reference. The data were converted to bone loss percentages caused by ligature: (ligated - unligated) x 100/ligated. RESULTS: When comparing the distance and area methods, no statistically significant difference was observed (p>0.05). Both methodologies indicated that the maxilla presented greater bone loss than the mandible and it was more accentuated on the buccal side than on the palatal side (p<0.05). CONCLUSIONS: The findings of this study show that both the area and the distance methods can be used to evaluate bone loss caused by ligature placement in rats, and suggest applying the morphometric methodology to the maxilla on the buccal side.

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Rosilene Fernandes da Rocha

Papers

Evaluation of digital optical density of bone repair in rats medicated with ketoprofen

Low caloric value of ethanol itself increases alveolar bone loss in ligature-induced periodontitis in male rats

Effects of experimental osteoporosis and low calcium intake on postextraction sockets of rats.

Evaluation of two morphometric methods of bone loss percentages caused by periodontitis in rats in different locations

Quem é e o que Pensa o Graduando de Odontologia