Gabriela Rezende Yanagihara

Effects of long-term administration of omeprazole on bone mineral density and the mechanical properties of the bone

Objectives Epidemiological studies have shown a relationship between long-term use of proton pump inhibitors and bone metabolism. However, this relationship has not yet become established. The aim of the present study was to analyze the mechanical properties and bone mineral density (BMD) of rats that were subjected to long-term omeprazole use. Methods Fifty Wistar rats weighing between 200 and 240 g were divided equally into five groups: OMP300 (omeprazole intake at a dose of 300 μmoL/kg/day); OMP200 (200 μmoL/kg/day); OMP40 (40 μmoL/kg/day); OMP10 (10 μmoL/kg/day); and Cont (control group; intake of dilution vehicle). The solutions were administered for 90 consecutive days. After the rats had been sacrificed, their BMD, the mechanical properties of the dissected femurs and their serum Ca++ levels were analyzed. Results The BMD of the OMP300 group was lower than that of the controls (p = 0.006). There was no difference on comparing the OMP200, OMP40 and OMP10 groups with the controls. The maximum strength and rigidity of the femur did not differ in the experimental groups in comparison with the controls. The OMP300 group had a statistically lower serum Ca++ concentration than that of the controls (p = 0.049), but the other groups did not show any difference in relation to the controls. Conclusion Daily intake of 300 μmoL/kg/day of omeprazole decreased the BMD of the femur, but without changes to the rigidity and strength of the femur in adult rats.

Effect of Treatment With Simvastatin on Bone Microarchitecture of the Femoral Head in an Osteoporosis Animal Model

The objective of this study was to evaluate the microarchitecture and trabecular bone strength at the distal region of the femur, and its biomechanical properties with simvastatin administration with two different doses in ovariectomized (OVX) rats. Ninety rats were divided into six groups to evaluate treatment with the simvastatin drug (n = 15): SH (Sham surgery), SH‐5 (5 mg simvastatin), SH‐20 (20 mg simvastatin), OVX, OVX‐5, and OVX‐20. Euthanasia was performed at three different times, five animals per period: 7, 14, and 28 days. The effectiveness of the treatments was evaluated by mechanical testing and histomorphometric analysis of the femurs. The results of analysis by the linear model of mixed effects showed 20 mg of simvastatin results in increased trabecular bone after 14 days (P = 0.039) of ingestion in ovariectomized animals. However, ingestion of 5 mg of simvastatin is able to sensitize the trabecular bone only at 28 days (P = 0.005) of ingestion. In the mechanical tests stiffness improves within 28 days (P = 0.003). Regarding maximum strength, no statistical differences were observed. According to these results, it can be concluded that for a decrease in oral intake, longer treatment times are required. Microsc. Res. Tech. 79:684–690, 2016.

High-impact exercise in rats prior to and during suspension can prevent bone loss

High-impact exercise has been considered an important method for treating bone loss in osteopenic experimental models. In this study, we investigated the effects of osteopenia caused by inactivity in femora and tibiae of rats subjected to jump training using the rat tail suspension model. Eight-week-old female Wistar rats were divided into five groups (n=10 each group): jump training for 2 weeks before suspension and training during 3 weeks of suspension; jump training for 2 weeks before suspension; jump training only during suspension; suspension without any training; and a control group. The exercise protocol consisted of 20 jumps/day, 5 days/week, with a jump height of 40 cm. The bone mineral density of the femora and tibiae was measured by double energy X-ray absorptiometry and the same bones were evaluated by mechanical tests. Bone microarchitecture was evaluated by scanning electron microscopy. One-way ANOVA was used to compare groups. Significance was determined as P<0.05. Regarding bone mineral density, mechanical properties and bone microarchitecture, the beneficial effects were greater in the bones of animals subjected to pre-suspension training and subsequently to training during suspension, compared with the bones of animals subjected to pre-suspension training or to training during suspension. Our results indicate that a period of high impact exercise prior to tail suspension in rats can prevent the installation of osteopenia if there is also training during the tail suspension.

Analysis of fracture healing in osteopenic bone caused by disuse: experimental study

Osteoporosis has become a serious global public health issue. Hence, osteoporotic fracture healing has been investigated in several previous studies because there is still controversy over the effect osteoporosis has on the healing process. The current study aimed to analyze two different periods of bone healing in normal and osteopenic rats. Sixty, 7-week-old female Wistar rats were randomly divided into four groups: unrestricted and immobilized for 2 weeks after osteotomy (OU2), suspended and immobilized for 2 weeks after osteotomy (OS2), unrestricted and immobilized for 6 weeks after osteotomy (OU6), and suspended and immobilized for 6 weeks after osteotomy (OS6). Osteotomy was performed in the middle third of the right tibia 21 days after tail suspension, when the osteopenic condition was already set. The fractured limb was then immobilized by orthosis. Tibias were collected 2 and 6 weeks after osteotomy, and were analyzed by bone densitometry, mechanical testing, and histomorphometry. Bone mineral density values from bony calluses were significantly lower in the 2-week post-osteotomy groups compared with the 6-week post-osteotomy groups (multivariate general linear model analysis, P<0.000). Similarly, the mechanical properties showed that animals had stronger bones 6 weeks after osteotomy compared with 2 weeks after osteotomy (multivariate general linear model analysis, P<0.000). Histomorphometry indicated gradual bone healing. Results showed that osteopenia did not influence the bone healing process, and that time was an independent determinant factor regardless of whether the fracture was osteopenic. This suggests that the body is able to compensate for the negative effects of suspension.

Effects of high-impact exercise on the physical properties of bones of ovariectomized rats fed to a high-protein diet

The aim of this study was to evaluate the effects of high‐impact physical exercise as a prophylactic and therapeutic means in osteopenic bones of rats submitted to ovariectomy and protein diet intake. A total of 64 Wistar rats were divided into eight groups (n = 8 each), being: OVX, ovx, standard diet and sedentary; OVXE, ovx, standard diet and jump; OVXP, ovx, high‐protein diet and sedentary; and OVXEP, ovx, high‐protein diet and jump; SH, sham, standard diet and sedentary; SHE, sham, standard diet and jump; SHP, sham, high‐protein diet and sedentary; and SHEP, sham, high‐protein diet and jump. OVX surgery consists of ovariectomy, and sham was the control surgery. The jumping protocol consisted of 20 jumps/day, 5 days/week. The bone structure was evaluated by densitometry, mechanical tests, histomorphometric, and immunohistochemical analyses. A high‐protein diet resulted in increased bone mineral density (P = .049), but decreased maximal load (P = .026) and bone volume fraction (P = .023). The benefits of physical exercise were demonstrated by higher values of the maximal load in the trained groups compared to the sedentary groups (P < .001). The sham groups had decreased immunostaining of osteocalcin (P = .004) and osteopontin (P = .010) compared to ovx groups. However, the high‐protein diet (P = .005) and jump exercise (P = .017) resulted in lower immunostaining of osteopontin compared to the standard diet and sedentary groups, respectively. In this experimental model, it was concluded that ovariectomy and a high‐fat diet can negatively affect bone tissue and the high‐impact exercise was not enough to suppress the deleterious effects caused by the protein diet and ovariectomy.

Effects of simvastatin associated with exercise on the mechanical resistance of muscle and bone in rats

Objective The aim of the present study was to evaluate the influence of simvastatin on mechanical properties of muscle and bone in hypercholesterolemic rats submitted to physical exercise. Methods Ten male Wistar rats were submitted to a high-fat diet rich in cholesterol for 90 days. The animals were then divided into two groups: animals treated with physical exercise (EG) and animals treated with physical exercise and simvastatin (ESG). Protocols for physical exercise in water and simvastatin administration were performed for eight weeks. After this period, the animals were euthanized; the left tibia and right gastrocnemius muscle were dissected for mechanical analysis, and the right tibia for densitometry. The data were analyzed using Students t-test, considering a level of significance of 5%. Results The comparison of maximum load and stiffness revealed no significant differences between the groups for both the tibia (p = 0.851 and p = 0.259) and the gastrocnemius (p = 0.911 and p = 0.083). The tibia BMD also showed no significant difference between the groups (p = 0.803). Conclusion Simvastatin had no negative effects on mechanical properties in tibia and gastrocnemius of hypercholesterolemic rats submitted to physical exercise.

Effect of coffee and calcium administration in the bone quality

P101 COMPARISON OF THE INTERNATIONAL REFERENCE VALUES OF BONE SPEED OF SOUND IN PEDIATRIC POPULATION: META-ANALYSIS R. Rivas-Ruiz, G. Huitrón, J. Salmeron-Castro, J. O. Talavera, J. Tamayo, P. Clark, D. O. Castelán-Martínez, L. Méndez-Sánchez Centro de Adiestramiento en Investigación Clínica, IMSS, México City, Mexico, Centro de Investigación en Ciencias Médicas, UAEM, Toluca, Mexico, Unidad de Investigación Epidemiológica y en Servicios de Salud, Instituto Mexicano del Seguro Social. Cuernavaca, Morelos, Mé, Cuernavaca, Mexico, Centro de Investigación en Ciencias Médicas, Universidad Autónoma del Estado de México, Toluca, Mexico, Comité Mexicano para la Prevención de la Osteoporosis, Mexico City, Mexico, Clinical Epidemiology Unit, Hospital Infantil de México, Federico Gómez, Mexico City, Mexico, Unidad de Investigación Epidemiológica, IMSS, Cuernavaca, Mexico