Tetranectin is a plasminogen-binding, homotrimeric protein belonging to the C-type lectin family of proteins. Tetranectin has been suggested to play a role in tissue remodeling, due to its ability to stimulate plasminogen activation and its expression in developing tissues such as developing bone and muscle. To test the functional role of tetranectin directly, we have generated mice with a targeted disruption of the gene. We report that the tetranectin-deficient mice exhibit kyphosis, a type of spinal deformity characterized by an increased curvature of the thoracic spine. The kyphotic angles were measured on radiographs. In 6-month-old normal mice (n ؍ 27), the thoracic angle was 73°؎ 2°, while in tetranectin-deficient 6-month-old mice (n ؍ 35), it was 93°؎ 2°(P < 0.0001). In approximately one-third of the mutant mice, X-ray analysis revealed structural changes in the morphology of the vertebrae. Histological analysis of the spines of these mice revealed an apparently asymmetric development of the growth plate and of the intervertebral disks of the vertebrae. In the most advanced cases, the growth plates appeared disorganized and irregular, with the disk material protruding through the growth plate. Tetranectin-null mice had a normal peak bone mass density and were not more susceptible to ovariectomy-induced osteoporosis than were their littermates as determined by dualemission X-ray absorptiometry scanning. These results demonstrate that tetranectin plays a role in tissue growth and remodeling. The tetranectin-deficient mouse is the first mouse model that resembles common human kyphotic disorders, which affect up to 8% of the population.
ADAM12-S transgenic mice exhibit a pronounced increase in the length of bones, such as femur, tibia, and vertebrae. The effect of ADAM12-S on longitudinal bone growth involves the modulation of chondrocyte proliferation and maturation, likely through proteolytic activities and altered cell-extracellular matrix interactions in the growth plate.Introduction: The disintegrin and metalloprotease ADAM12 is expressed in both osteoblasts and osteoclasts, suggesting a regulatory role of ADAM12 in bone. However, thus far, no in vivo function of ADAM12 in the skeleton has been reported. Materials and Methods: Transgenic mice expressing the secreted form of human ADAM12, ADAM12-S, or a truncated metalloprotease-deficient form of ADAM12-S in the circulation were used to study the effects of ADAM12 on the skeleton. In addition, murine chondrocyte cultures were used to study the effect of ADAM12-S on cell-extracellular matrix interactions. Results: ADAM12-S transgenic mice exhibit increased longitudinal bone growth. The increased bone length is progressive and age dependent, with a maximum increase of 17% seen in the femur from 6-month-old transgenic mice. The effect is gene dose dependent, being more pronounced in mice expressing higher levels of the transgene than in a lower-expressing line. Histological analysis revealed no alterations in the growth plate organization, but mean growth plate width was increased. Both the cellular incorporation of bromodeoxyuridine and the width of the collagen type X-positive hypertrophic zone were increased in the growth plate of ADAM12-S transgenic mice. Importantly, mice expressing a truncated form of ADAM12-S that lacked the pro-and metalloprotease domains showed no alterations in bone length, suggesting that protease activity is required for the ADAM12-S effect. In vitro studies showed that ADAM12-S inhibits chondrocyte adhesion to fibronectin and collagen type II. Conclusions: ADAM12-S stimulates bone growth in mice by modulating chondrocyte proliferation and maturation through mechanisms probably involving both metalloprotease and adhesion activities.
Forty three lung scans, obtained in 29 anaesthetized children, were evaluated and compared with 85 scans performed in 52 sedated children. Confluent high absorptive areas in the lower parts of the lungs were found in 35 (81%) of the scans performed in children under general anaesthesia but such areas were not found in the scans performed under sedation.--For general anaesthesia, halothane-N2O-O2 was used in all but one patient. The radiological changes are presumably due to a fall in functional residual capacity with consequent airway closure.--It is important not to misinterpret these anaesthesia-induced pulmonary changes which may obscure or mimic true pathological lesions, such as parenchymal and pleural metastases.
ABSTRACT. Objectives. To evaluate the reproducibility and the accuracy of pediatric radiologists' assessments of chest radiographs with respect to the presence or absence of heart defects in children with an asymptomatic heart murmur.Design. Ninety-eight children, ages 1 month to 15 years (median, 30.1 months), referred for evaluation of a heart murmur were consecutively included. They all had a standard chest radiograph and a color Doppler echocardiograph (CDE) performed. Six specialists in pediatric radiology evaluated the chest radiographs independently on two occasions 6 months apart. The radiologists were asked to classify each set of films into one of two categories: heart disease or no heart disease. The outcome of the CDE was considered the definite diagnosis. statistics were used to analyze the reproducibility of the radiologic assessments. Sensitivity, specificity, and the predictive value of a positive and a negative test were used for evaluation of the accuracy of the radiologic assessments.Results. Mean intra-and interobserver values were all <0.6, and the majority were <0.4. Mean sensitivity was 0.3 (range: 0.17-0.52), mean predictive value of a positive test was 0.4, implying that 60% of the positive assessments were falsely positive. Mean specificity was 0.86 (range: 0.75-0.93) and the mean predictive value of a negative test was 0.80 implying that 20% of the negative assessments were falsely negative.Conclusion We found a low reproducibility, as well as a low accuracy, of the radiologic assessments of the chest radiographs of children with an asymptomatic heart murmur with respect to the presence or absence of heart disease. A false-positive radiologic assessment of the chest radiograph with respect to heart defects causes unnecessary anxiety and further examinations, whereas a false-negative assessment might result in omission of relevant investigations and proper identification of the heart defect. We cannot recommend the use of chest radiographs in the initial evaluation of the asymptomatic child with a heart murmur. If a heart defect cannot be excluded by clinical examination a CDE must be performed. Pediatrics 1999;103(2). URL: http://www. pediatrics.org/cgi/content/full/103/2/e15; child, cardiac murmur, chest radiograph, reproducibility, accuracy.ABBREVIATION. CDE, color Doppler echocardiography.
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