Effects of synovial fluid from aseptic prosthesis loosening on collagen production in osteoblasts

Synovial fluid from a loose prosthesis may act as a vehicle for factors that regulate bone turnover. The effect of such synovial fluid on osteoblasts has been studied. Synovial fluid obtained from patients who underwent revision hip arthroplasty because of aseptic prosthesis loosening was studied regarding the effect on protein synthesis, procollagen I mRNA expression, the secretion of procollagen I carboxyterminal propeptide (PICP) and osteocalcin in MG63 osteoblasts. Protein synthesis was increased and procollagen I mRNA expression was decreased by synovial fluid from patients with prosthesis loosening. Synovial fluid stimulated the total PICP in cell medium, but there was no change after correction for cell protein content in the cells. Synovial fluid in patients with prosthesis loosening has a general stimulatory effect on collagen formation and osteoblast proliferation because of a stimulatory effect on cell growth. Aseptic prosthesis loosening may be associated with an increase in bone formation.

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Résumé  Le liquide synovial provenant de prothèses descellées peut être considéré comme le support de facteurs de la régulation du turn over osseux. Pour cela ont été étudiés les effets de ce liquide sur les ostéoblastes. Le liquide synovial obtenu de patients ayant nécessité une révision de prothèse de hanche descellée pour descellement aseptique a été utilisé afin d’évaluer les effets de ce liquide sur la synthèse des protéines, pro collagène, I mRNA expression sur la sécrétion du pro collagène I carboxyterminale propeptide et sur l’ostéocalcine dans les ostéoblastes MG63. Cette synthèse protéinique est augmentée et l’expression du pro collagène I mRNA diminue lorsque le liquide synovial de ces patients est adjoint. Le liquide synovial stimule le PICP mais il n’y a pas de modification des protéines cellulaires contenues dans les ostéoblastes. Conclusion, le fluide synovial chez ces patients présentant un descellement prothétique a un effet stimulant sur la formation du collagène et la prolifération des ostéoblastes. Le descellement aseptique des prothèses peut être associé avec une augmentation de la formation osseuse.

     

Learning the lessons from conflict: Pre-hospital cervical spine stabilisation following ballistic neck trauma

Background

Current ATLS protocols dictate that spinal precautions should be in place when a casualty has sustained trauma from a significant mechanism of injury likely to damage the cervical spine. In hostile environments, the application of these precautions can place pre-hospital medical teams at considerable personal risk. It may also prevent or delay the identification of airway problems. In today's global threat from terrorism, this hostile environment is no longer restricted to conflict zones. The aim of this study was to ascertain the incidence of cervical spine injury following penetrating ballistic neck trauma in order to evaluate the need for pre-hospital cervical immobilisation in these casualties.

Methods

We retrospectively reviewed the medical records of British military casualties of combat, from Iraq and Afghanistan presenting with a penetrating neck injury during the last 5.5 years. For each patient, the mechanism of injury, neurological state on admission, medical and surgical intervention was recorded.

Results

During the study period, 90 casualties sustained a penetrating neck injury. The mechanism of injury was by explosion in 66 (73%) and from gunshot wounds in 24 (27%). Cervical spine injuries (either cervical spine fracture or cervical spinal cord injury) were present in 20 of the 90 (22%) casualties, but only 6 of these (7%) actually survived to reach hospital. Four of this six subsequently died from injuries within 72 h. Only 1 (1.8%) of the 56 survivors to reach a surgical facility sustained an unstable cervical spine injury that required surgical stabilisation. This patient later died as result of a co-existing head injury.

Conclusions

Penetrating ballistic trauma to the neck is associated with a high mortality rate. Our data suggests that it is very unlikely that penetrating ballistic trauma to the neck will result in an unstable cervical spine in survivors. In a hazardous environment (e.g. shooting incidents or terrorist bombings), the risk/benefit ratio of mandatory spinal immobilisation is unfavourable and may place medical teams at prolonged risk. In addition cervical collars may hide potential life-threatening conditions.     

Identification and characterization of two zebrafish nectin‐1 genes that are differentially expressed in the developing eye and brain

Nectins are cell adhesion molecules of the immunoglobulin type that play important roles in the development of the nervous system. We have characterized two paralogous zebrafish nectin‐1 genes, nectin‐1a and nectin‐1b, that differ in expression. Nectin‐1a expression is first found in the anterior neural keel and later in the optic cup. In the retina, nectin‐1a appears in the outer part and extends inwards, while nectin‐1b starts in the inner part and spreads outwards. Only nectin‐1a was detected in the cornea, the lens, and in the region of photoreceptor cell differentiation in the retina. Both genes were expressed in ganglion cells and inner nuclear neurons. In the brain, nectin‐1a was restricted to the epiphysis and a cluster of cells in the posterior hindbrain, whereas nectin‐1b was found in several brain areas. Zebrafish may, therefore, be a useful model for identifying different functions of nectin‐1 in the developing eye and nervous system. Developmental Dynamics 238:43–55, 2009. © 2008 Wiley‐Liss, Inc.     

Ultrasound mimics the effect of mechanical loading on bone formation in vivo on rat ulnae

While the effect of ultrasound as an extreme example of low-magnitude high-frequency stimulation has been explored in the response of bone to injury, little is known about its effect on normal bone. This experiment was designed to test the hypothesis that ultrasound exerts a similar influence on bone as mechanical stimulation at a physiological level. Three groups of female Wistar rats were anaesthetised (6 per group). In one group, the left ulna was loaded cyclically in vivo 40 times, repeated on a further 5 occasions on alternate days. In a second group, transcutaneous low-intensity pulsed ultrasound stimulation was applied to the left ulnae for the same duration as the period of loading. In a third group, loading and ultrasound stimulation were applied concurrently. The right ulna served as non-loaded control in each animal. At the end of the experiment after 14 days, both ulnae were removed. Induced bone formation was assessed by measuring the proportion of medial periosteal bone surface with double label (dLS/BS, %) and by calculation of mineral apposition rate (MAR) from the inter-label distance. All three treatments induced a significant periosteal response, increasing dLS/BS values from <10% in control limbs to >80% in treated limbs. Increases in MAR of experimental ulnae versus contralateral control ulnae were 2.9 (+/-0.9), 8.6 (+/-2.4) and 8.7 microm (+/-3.2) for the ultrasound only, ultrasound and load, and load only groups, respectively. The effects of loading plus ultrasound were not significantly different from ultrasound alone. These data suggest that ultrasound is able to induce changes in bone that share at least some features with mechanical loading.