Australopithecus garhi: a new species of early hominid from Ethiopia.
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The lack of an adequate hominid fossil record in eastern Africa between 2 and 3 million years ago (Ma) has hampered investigations of early hominid phylogeny. Discovery of 2.5 Ma hominid cranial and dental remains from the Hata beds of Ethiopia's Middle Awash allows recognition of a new species of Australopithecus. This species is descended from Australopithecus afarensis and is a candidate ancestor for early Homo. Contemporary postcranial remains feature a derived humanlike humeral/femoral ratio and an apelike upper arm-to-lower arm ratio. (+info)
Acceleration of increase in bone mineral content by low-intensity ultrasound energy in leg lengthening.
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The effect of ultrasound energy on bone has been studied for a long time. In particular, multiple effects of low-intensity ultrasound energy have recently been demonstrated experimentally, such as increases in bending strength of fracture callus, acceleration of soft callus formation and endochondral ossification of the callus at the fracture site, stimulation of aggrecan gene expression, or modulation of TGF-beta synthesis and increase of calcium uptake. Clinically, prospective, randomized, and double-blind trials showed the efficacy of low-intensity ultrasound beam stimulation in the acceleration of fracture healing, with a significant decrease in the time to healing. On the other hand, callotasis, a popular method for bone lengthening, requires much time for new bone formation, and an external fixator must be remain on the patient for a long period. This is one of the major problems of the callotasis technique. If ultrasound energy stimulation could accelerate the rate of callus formation in callotasis, the external fixator could be removed earlier, the treatment period could be shortened, and the patient could return to daily activities more quickly. We report on the use low-intensity ultrasound beam stimulation during leg lengthening with the callotasis method in which callus formation was poor. (+info)
Vertebrate aristaless-related genes.
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Aristaless-related genes, a subset of the Paired-related homeobox genes, have in the past few years emerged as a group of regulators of essential events during vertebrate embryogenesis. One group of aristaless-related genes has been linked to the morphogenesis of the craniofacial and appendicular skeleton by their expression patterns and by the phenotypes of natural and artificial mouse mutants. Expression and function in the nervous system characterise a second group, and a third group, the Pitx genes, have been shown to have many different roles, including functions in the pituitary, left-right determination and limb development. (+info)
Gelsolin deficiency blocks podosome assembly and produces increased bone mass and strength.
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Osteoclasts are unique cells that utilize podosomes instead of focal adhesions for matrix attachment and cytoskeletal remodeling during motility. We have shown that osteopontin (OP) binding to the alpha(v)beta(3) integrin of osteoclast podosomes stimulated cytoskeletal reorganization and bone resorption by activating a heteromultimeric signaling complex that includes gelsolin, pp(60c-src), and phosphatidylinositol 3'-kinase. Here we demonstrate that gelsolin deficiency blocks podosome assembly and alpha(v)beta(3)-stimulated signaling related to motility in gelsolin-null mice. Gelsolin-deficient osteoclasts were hypomotile due to retarded remodeling of the actin cytoskeleton. They failed to respond to the autocrine factor, OP, with stimulation of motility and bone resorption. Gelsolin deficiency was associated with normal skeletal development and endochondral bone growth. However, gelsolin-null mice had mildly abnormal epiphyseal structure, retained cartilage proteoglycans in metaphyseal trabeculae, and increased trabecular thickness. With age, the gelsolin-deficient mice expressed increased trabecular and cortical bone thickness producing mechanically stronger bones. These observations demonstrate the critical role of gelsolin in podosome assembly, rapid cell movements, and signal transduction through the alpha(v)beta(3) integrin. (+info)
Limb reconstruction after high energy trauma.
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Limb reconstruction techniques rely on stable external fixation to provide early limb function after major long bone injury. Bone may be generated by callus distraction techniques and internal techniques of moving bone segments used to fill bone defects. Soft tissue defects may be treated by acute shortening, although skin defects will also close spontaneously during bone transport as the leading edge of bone is covered with granulation tissue. External fixation is also used to cross joints permitting rest and repair of the joint. Hinges placed within the bars of the fixation frame may be used to correct deformities in the bone and soft tissue contractures using closed distraction techniques. These techniques are appropriate to metaphyseal fractures and diaphyseal fractures with bone loss. A major advantage is the lack of donor site morbidity, associated with skin flaps and large bone grafts. Acceptance of these techniques is growing whilst the methodology continues to improve. In more complicated cases, specialist training and dedicated hospital units with multidisciplinary support is desirable. (+info)
Uncoupling of chondrocyte death and vascular invasion in mouse galectin 3 null mutant bones.
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Galectin 3 is a beta-galactoside binding protein which localizes to the cytoplasm of proliferative, mature, and hypertrophic chondrocytes in the growth plate cartilage of developing long bones. To elucidate the function of galectin 3 during bone development, we examined the epiphyseal femurs and tibias of fetal mice carrying a null mutation for the galectin 3 gene. Detailed histological and ultrastructural studies identified abnormalities in the cells of the proliferative, mature, and hypertrophic zones and in the extracellular matrix of the hypertrophic zone, as well as a reduction in the total number of hypertrophic chondrocytes. The expression patterns of several chondrocyte and bone cell markers were analyzed and revealed a subtle modification of Ihh expression in the galectin 3 mutant growth plate. A striking difference was observed at the chondrovascular junction where many empty lacunae are present. In addition, large numbers of condensed chondrocytes exhibiting characteristic signs of cell death were found in the late hypertrophic zone, indicating that the rate of chondrocyte death is increased in the mutants. These results suggest a role for galectin 3 as a regulator of chondrocyte survival. In addition, this unique phenotype shows that the elimination of chondrocytes and vascular invasion can be uncoupled and indicates that galectin 3 may play a role in the coordination between chondrocyte death and metaphyseal vascularization. (+info)
Assessment of the clinical significance of asymptomatic lower extremity uptake abnormality in young athletes.
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This study was undertaken to evaluate our hypothesis that most asymptomatic lower extremity uptake abnormalities are of no clinical consequence and to assess whether these findings should affect patient care. METHODS: One hundred consecutive young athletes referred for bone scintigraphy by a sports medicine clinic because of low back pain were evaluated for the presence of asymptomatic bone scan abnormalities in the lower extremities. The patients were then reexamined by the referring sports medicine physician, who had full knowledge of the bone scan results. Scintigraphic findings were correlated with the clinical evaluation at the time of scintigraphy and on follow-up evaluations ranging from 8 to 14 mo later. RESULTS: Asymptomatic lower extremity abnormalities were present in 34% of patients. There were abnormalities of the feet in 30 patients (focal uptake in 26 patients, diffuse uptake in 10 patients), the tibia in 13 patients (2 focal uptake, 11 diffuse uptake), and the femur in 2 patients (both with diffuse uptake). None of the regions of abnormal lower extremity uptake was symptomatic at the time of initial evaluation. There was no change in the clinical management of any patient because of the scan findings. None of the patients was advised to restrict the activity level because of the asymptomatic scan findings. None of the regions of scan abnormality became symptomatic on follow-up evaluation. CONCLUSION: This study shows that asymptomatic bone scintigraphic abnormalities of the feet, as well as diffuse abnormalities of the tibia, are common in young athletes. These findings are most likely of no clinical consequence and do not require a change in the activity level. Focal abnormalities of the femur or tibia are not commonly seen in asymptomatic young athletes. (+info)
Growth hormone and segmental growth in survivors of head and neck embryonal rhabdomyosarcoma.
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AIMS: To assess the impact of treatment for embryonal rhabdomyosarcoma on spinal growth and limb length and examine the response of these parameters to growth hormone (GH) treatment. METHODS: We conducted a retrospective case note review of 17 survivors of head and neck rhabdomyosarcoma followed up at a single institution. All children had been treated with chemotherapy and local radiotherapy. Growth velocity, height, sitting height, and subischial limb length SDS scores were analysed. RESULTS: Growth failure secondary to isolated GH deficiency (GHD) developed in 7/17 patients. GHD occurred at a median (range) of 3.4 (1.3-9.9) years after radiotherapy tumour doses of 46 (40-50) Gy. Growth velocity, height, and subischial limb length SDS were significantly reduced in the GHD group and improved with GH therapy. CONCLUSIONS: GH treatment resulted in a significant improvement in sitting height SDS. We discuss the unexpected improvement in spinal growth in survivors with GHD. (+info)