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An experimental model of distraction osteogenesis in rat mandibular alveolar bone
Abstracts very rare and its management difficult. Rapid enlargement of FD lesions is suggestive of cystic degeneration. MRI is very useful for diagnosis. This article is part of a Special Issue entitled AAOMM 2010 Abstracts.
doi:10.1016/j.bone.2011.03.734
An experimental model of distraction osteogenesis in rat mandibular alveolar bone M.M. Pujadas Bigi, S. Kokubu, M. Lewicki, M.M. Nenda, A.M. Ubios, P.M. Mandalunis Histology and Embryology Department, School of Dentistry, UBA, Argentina Introduction: Osteogenesis distraction (DO) is a surgical technique that allows distraction of the fracture callus. It has been used extensively in endochondral long bones but not in the craniofacial skeleton of endomembranous origin. Mandibular alveolar bone of endomembranous origin contains teeth sockets; it is a functional bone that undergoes bone turnover at a higher rate than other bone tissues. The aim of our work was to present the development of an experimental model of DO in rat mandibular alveolar bone including all stages, i.e. animal procedures, laboratory determinations, histological procedures and histomorphometric measurements. Methods: 8 Wistar rats, 80 g bw, underwent extraction of all mandibular molars. At 400 g bw, right hemimandibular osteotomy was performed and the device was placed. After 6 days (latency) it was activated (0.175 mm/d once a day/ 6 days) and then left in place 28 days (consolidation phase). Rats were sacrificed and hemimandibles were resected. The technique was standardized to perform radiographs and hemimandible orientation was adjusted to allow obtaining comparable histologic sections. A method to record and compare these measurements was designed. H&E stained mesiodistally oriented hemimandible sections were obtained. Screw loosening and loss of the device during the consolidation phase were initial problems (SAIO, 2008). The original design was perfected to avoid mobility. Results: The new, improved device remained in place throughout the experiment. Comparable mesiodistally oriented sections were obtained. Conclusion: This experimental model of mandibular DO will allow studying the cellular and molecular events that take place during DO under different experimental conditions. This article is part of a Special Issue entitled AAOMM 2010 Abstracts.
doi:10.1016/j.bone.2011.03.735
Melatonin: A protective hormone of intestinal calcium absorption? A.R. Carpentieri, A.M. Marchionatti, A. del V. Perez, V.A. Centeno, V.A. Areco, N.G. Tolosa de Talamoni Laboratorio “Dr. Fernando Canas”, Bioquímica y Biología Molecular, Facultad de Medicina, Química y Física Biológicas, Facultad de Odontología, UNC, Argentina In a previous work, we have shown that melatonin (MEL) reverses the inhibitory effect of menadione (MEN) on chick intestinal calcium absorption. The aim of this work was to elucidate the molecular mechanisms underlying this response. Chicks were divided into 4 groups: 1) controls, 2) MEN treated, 3) MEL treated and 4) treated with MEL after MEN injection. Gene and protein expressions of molecules involved in the transcellular Ca2+ movement were studied by RT-PCR and Western blots, respectively. Oxidative stress and apoptosis were evaluated by different techniques. Results were assessed using one-way ANOVA followed by Bonferroni multiple comparison tests. The data show that MEN diminishes gene and protein expressions of the Ca2+ pump, which was completely reversed by MEL. Other genes involved in the transcellular cation movement were not altered by the treatments. MEN caused oxidative stress as judged by decrease in the GSH content, alteration in the mitochondrial membrane potential and increase in the activity of superoxide dismutase and catalase. All these effects were reversed by MEL. MEN provoked mitochondrial apoptosis as shown by increases in DNA fragmentation, cytochrome c expression and caspase-3 activity. MEL also counteracted these effects. MEL by itself did not alter any studied variable except the gene and protein expressions of the Ca2+ pump, which were stimulated by the hormone. In conclusion, MEL reverses the inhibitory effect of MEN on intestinal Ca2+ absorption counteracting the oxidative stress and apoptosis and enhancing the gene and protein expressions of the Ca2+ pump, the main molecule involved in the transcellular Ca2+ absorption. This article is part of a Special Issue entitled AAOMM 2010 Abstracts.
doi:10.1016/j.bone.2011.03.736
S287
Experimental model of BP-induced osteonecrosis of the jaw. Preliminary study G. Pellegrini, M. Gonzales-Chaves, C. Marotte, G. Bryk, R. Orzuza, J. Somoza, S. Friedman, S. Zeni Cát. Bioquímica Gral y Bucal, FOUBA, CONICET, Sección Osteopatías Médicas. Htal. de Clínicas UBA, Argentina Bisphosphonates (BPs) have been used for years in osteoporosis and neoplasia treatments. Osteonecrosis of the jaws (ONJ) as a potential negative side effect has been suggested. ONJ physiopathology remains unknown however it has been postulated that bone decrease by BPs could contribute. Objective: To develop an experimental model to investigate pathogenic aspects of BP-induced ONJ in oncological conditions. 24 female Wistar rats were OVX and remained without treatment for 60 days. They were inoculated with DMBA (SigmaAldrich, Arg) in a dose enough to cause 100% mammary tumor incidence. They were divided into 3 groups which received oncological doses of pamidronate (PAM) or zoledronic acid (ZOL) and a 3rd group received saline solution (Vh) for 5 months. After 4th month of treatment, a mandibular molar of 4 animals of each group, was extracted to distinguish between induced and spontaneous ONJ. Mucosal changes were observed. Extraction site healing was seen in Vh and PAM groups. Non-healed extraction sites, suppuration and inflammation signs were only observed in the ZOL group. Biochemistry: serum Ca (mg/dL) Vh = 10.0 ± 0.1a; ZOL = 10.0 ± 0.1a; PAM = 9.9 ± 0.1a (n.s.). P (mg/dL): Vh = 6.2 ± 0.2a; ZOL = 6.6 ± 0.2a; PAM = 7.4 ± 04b (p < 0.05). B-ALP (UI/L): Vh = 82 ± 7a; ZOL = 54 ± 3b; PAMI = 75 ± 7a (p < 0.02). ALP (UI/L): Vh = 498 ± 33a; ZOL = 435 ± 22a; PAM = 466 ± 14a (n.s). Although further studies must be done to improve this experimental model, under our experimental conditions ZOL treated rats that went under dental intervention showed delayed wound healing of the extraction socket and low bone turn over, both situations could be imply in the appearance of ONJ. This article is part of a Special Issue entitled AAOMM 2010 Abstracts.
doi:10.1016/j.bone.2011.03.737
Solitary parathyroid adenoma in a 16 year old girl. Case report and postsurgery follow up G. Viterbo, C. Tau, V. Ayarzabal, J. Castagneto Metabolismo cálcico y óseo, Endocrinología y Cirugía, Hospital de Pediatría J.P. Garrahan, Buenos Aires, Argentina Primary hyperparathyroidism is extremely rare during childhood and adolescence. We report here a clinical case of a 16 year and 7 month-old-girl who began 6 months before, with renal colics and nephrolithiasis. She had no personal or familial history of any disease. Physical examination was unremarkable. Biochemical exams showed hypercalcemia: 11.8 to 13.9 mg/dl, hypophosphatemia: 2.5 mg/ dl, hypercalciuria: 7.6 mg/kg/day, and hyperparathyroidism: PTH: 317 to 569 pg/ml (n.v. 12–72). Urine catecholamines were normal. The neck ultrasonography and technesium-99m Sestamibi reported parathyroid adenoma. Spine and whole body bone densitometry showed severe osteopenia: L2–L4: 0.83 g/cm2, Z-score: −3.5 and 0.8 g/cm2, Z-score: −4.1, respectively. A parathyroid adenoma situated below the left lobe of the thyroid gland was successfully removed with surgery. The histopathology reported parathyroid adenoma of chief cells. PTH fell to 40 and 27 pg/ml, 15 and 30 minutes after the adenoma was removed. Hypocalcemia was detected 18 hours after surgery (8.3 mg/ dl). Calcitriol 0.75 μg and calcium 1 g/day were administered. Slight hypocalcemia persisted during the next 15 days when it fell to a minimum of 5.8 mg/dl, requiring the increase of calcitriol to 1.5 μg and calcium to 2 g/day. Spine bone densitometry repeated one month after surgery showed an increase of 35% of the bone mineral density (L2–L4: 0.96 g/cm2, Z-score: −2.4). In summary: We report a case of primary hyperparathyroidism in an adolescent, due to parathyroid adenoma. After the extirpation of the tumor, the outcome and follow up were good. She needed calcitriol and calcium to normalize the calcemia, and one month after surgery, she had a partial recovery of bone mass. This article is part of a Special Issue entitled AAOMM 2010 Abstracts.
doi:10.1016/j.bone.2011.03.738
17β-Estradiol negatively regulates bax proapoptotic actions in skeletal muscle cells A. Ronda, A. La Colla, G. Stockman, R. Boland, A. Vasconsuelo Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur, 8000 Bahía Blanca, Argentina It is known that estrogens exert actions in skeletal muscle. Degenerative pathologies of the muscle mass, like sarcopenia, observed in menopausic women are due to decreased estrogen levels. Likewise, this hormone is important in the improvement of the muscular mass in cases of atrophy. Although the mechanisms underlying sarcopenia are far for being clarified, evidence suggests that an age-related acceleration of myocyte loss via apoptosis might
doi:10.1016/j.bone.2011.03.734
An experimental model of distraction osteogenesis in rat mandibular alveolar bone M.M. Pujadas Bigi, S. Kokubu, M. Lewicki, M.M. Nenda, A.M. Ubios, P.M. Mandalunis Histology and Embryology Department, School of Dentistry, UBA, Argentina Introduction: Osteogenesis distraction (DO) is a surgical technique that allows distraction of the fracture callus. It has been used extensively in endochondral long bones but not in the craniofacial skeleton of endomembranous origin. Mandibular alveolar bone of endomembranous origin contains teeth sockets; it is a functional bone that undergoes bone turnover at a higher rate than other bone tissues. The aim of our work was to present the development of an experimental model of DO in rat mandibular alveolar bone including all stages, i.e. animal procedures, laboratory determinations, histological procedures and histomorphometric measurements. Methods: 8 Wistar rats, 80 g bw, underwent extraction of all mandibular molars. At 400 g bw, right hemimandibular osteotomy was performed and the device was placed. After 6 days (latency) it was activated (0.175 mm/d once a day/ 6 days) and then left in place 28 days (consolidation phase). Rats were sacrificed and hemimandibles were resected. The technique was standardized to perform radiographs and hemimandible orientation was adjusted to allow obtaining comparable histologic sections. A method to record and compare these measurements was designed. H&E stained mesiodistally oriented hemimandible sections were obtained. Screw loosening and loss of the device during the consolidation phase were initial problems (SAIO, 2008). The original design was perfected to avoid mobility. Results: The new, improved device remained in place throughout the experiment. Comparable mesiodistally oriented sections were obtained. Conclusion: This experimental model of mandibular DO will allow studying the cellular and molecular events that take place during DO under different experimental conditions. This article is part of a Special Issue entitled AAOMM 2010 Abstracts.
doi:10.1016/j.bone.2011.03.735
Melatonin: A protective hormone of intestinal calcium absorption? A.R. Carpentieri, A.M. Marchionatti, A. del V. Perez, V.A. Centeno, V.A. Areco, N.G. Tolosa de Talamoni Laboratorio “Dr. Fernando Canas”, Bioquímica y Biología Molecular, Facultad de Medicina, Química y Física Biológicas, Facultad de Odontología, UNC, Argentina In a previous work, we have shown that melatonin (MEL) reverses the inhibitory effect of menadione (MEN) on chick intestinal calcium absorption. The aim of this work was to elucidate the molecular mechanisms underlying this response. Chicks were divided into 4 groups: 1) controls, 2) MEN treated, 3) MEL treated and 4) treated with MEL after MEN injection. Gene and protein expressions of molecules involved in the transcellular Ca2+ movement were studied by RT-PCR and Western blots, respectively. Oxidative stress and apoptosis were evaluated by different techniques. Results were assessed using one-way ANOVA followed by Bonferroni multiple comparison tests. The data show that MEN diminishes gene and protein expressions of the Ca2+ pump, which was completely reversed by MEL. Other genes involved in the transcellular cation movement were not altered by the treatments. MEN caused oxidative stress as judged by decrease in the GSH content, alteration in the mitochondrial membrane potential and increase in the activity of superoxide dismutase and catalase. All these effects were reversed by MEL. MEN provoked mitochondrial apoptosis as shown by increases in DNA fragmentation, cytochrome c expression and caspase-3 activity. MEL also counteracted these effects. MEL by itself did not alter any studied variable except the gene and protein expressions of the Ca2+ pump, which were stimulated by the hormone. In conclusion, MEL reverses the inhibitory effect of MEN on intestinal Ca2+ absorption counteracting the oxidative stress and apoptosis and enhancing the gene and protein expressions of the Ca2+ pump, the main molecule involved in the transcellular Ca2+ absorption. This article is part of a Special Issue entitled AAOMM 2010 Abstracts.
doi:10.1016/j.bone.2011.03.736
S287
Experimental model of BP-induced osteonecrosis of the jaw. Preliminary study G. Pellegrini, M. Gonzales-Chaves, C. Marotte, G. Bryk, R. Orzuza, J. Somoza, S. Friedman, S. Zeni Cát. Bioquímica Gral y Bucal, FOUBA, CONICET, Sección Osteopatías Médicas. Htal. de Clínicas UBA, Argentina Bisphosphonates (BPs) have been used for years in osteoporosis and neoplasia treatments. Osteonecrosis of the jaws (ONJ) as a potential negative side effect has been suggested. ONJ physiopathology remains unknown however it has been postulated that bone decrease by BPs could contribute. Objective: To develop an experimental model to investigate pathogenic aspects of BP-induced ONJ in oncological conditions. 24 female Wistar rats were OVX and remained without treatment for 60 days. They were inoculated with DMBA (SigmaAldrich, Arg) in a dose enough to cause 100% mammary tumor incidence. They were divided into 3 groups which received oncological doses of pamidronate (PAM) or zoledronic acid (ZOL) and a 3rd group received saline solution (Vh) for 5 months. After 4th month of treatment, a mandibular molar of 4 animals of each group, was extracted to distinguish between induced and spontaneous ONJ. Mucosal changes were observed. Extraction site healing was seen in Vh and PAM groups. Non-healed extraction sites, suppuration and inflammation signs were only observed in the ZOL group. Biochemistry: serum Ca (mg/dL) Vh = 10.0 ± 0.1a; ZOL = 10.0 ± 0.1a; PAM = 9.9 ± 0.1a (n.s.). P (mg/dL): Vh = 6.2 ± 0.2a; ZOL = 6.6 ± 0.2a; PAM = 7.4 ± 04b (p < 0.05). B-ALP (UI/L): Vh = 82 ± 7a; ZOL = 54 ± 3b; PAMI = 75 ± 7a (p < 0.02). ALP (UI/L): Vh = 498 ± 33a; ZOL = 435 ± 22a; PAM = 466 ± 14a (n.s). Although further studies must be done to improve this experimental model, under our experimental conditions ZOL treated rats that went under dental intervention showed delayed wound healing of the extraction socket and low bone turn over, both situations could be imply in the appearance of ONJ. This article is part of a Special Issue entitled AAOMM 2010 Abstracts.
doi:10.1016/j.bone.2011.03.737
Solitary parathyroid adenoma in a 16 year old girl. Case report and postsurgery follow up G. Viterbo, C. Tau, V. Ayarzabal, J. Castagneto Metabolismo cálcico y óseo, Endocrinología y Cirugía, Hospital de Pediatría J.P. Garrahan, Buenos Aires, Argentina Primary hyperparathyroidism is extremely rare during childhood and adolescence. We report here a clinical case of a 16 year and 7 month-old-girl who began 6 months before, with renal colics and nephrolithiasis. She had no personal or familial history of any disease. Physical examination was unremarkable. Biochemical exams showed hypercalcemia: 11.8 to 13.9 mg/dl, hypophosphatemia: 2.5 mg/ dl, hypercalciuria: 7.6 mg/kg/day, and hyperparathyroidism: PTH: 317 to 569 pg/ml (n.v. 12–72). Urine catecholamines were normal. The neck ultrasonography and technesium-99m Sestamibi reported parathyroid adenoma. Spine and whole body bone densitometry showed severe osteopenia: L2–L4: 0.83 g/cm2, Z-score: −3.5 and 0.8 g/cm2, Z-score: −4.1, respectively. A parathyroid adenoma situated below the left lobe of the thyroid gland was successfully removed with surgery. The histopathology reported parathyroid adenoma of chief cells. PTH fell to 40 and 27 pg/ml, 15 and 30 minutes after the adenoma was removed. Hypocalcemia was detected 18 hours after surgery (8.3 mg/ dl). Calcitriol 0.75 μg and calcium 1 g/day were administered. Slight hypocalcemia persisted during the next 15 days when it fell to a minimum of 5.8 mg/dl, requiring the increase of calcitriol to 1.5 μg and calcium to 2 g/day. Spine bone densitometry repeated one month after surgery showed an increase of 35% of the bone mineral density (L2–L4: 0.96 g/cm2, Z-score: −2.4). In summary: We report a case of primary hyperparathyroidism in an adolescent, due to parathyroid adenoma. After the extirpation of the tumor, the outcome and follow up were good. She needed calcitriol and calcium to normalize the calcemia, and one month after surgery, she had a partial recovery of bone mass. This article is part of a Special Issue entitled AAOMM 2010 Abstracts.
doi:10.1016/j.bone.2011.03.738
17β-Estradiol negatively regulates bax proapoptotic actions in skeletal muscle cells A. Ronda, A. La Colla, G. Stockman, R. Boland, A. Vasconsuelo Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur, 8000 Bahía Blanca, Argentina It is known that estrogens exert actions in skeletal muscle. Degenerative pathologies of the muscle mass, like sarcopenia, observed in menopausic women are due to decreased estrogen levels. Likewise, this hormone is important in the improvement of the muscular mass in cases of atrophy. Although the mechanisms underlying sarcopenia are far for being clarified, evidence suggests that an age-related acceleration of myocyte loss via apoptosis might