Lubricin/Proteoglycan 4 binds to and regulates the activity of Toll-Like Receptors In Vitro.

Proteoglycan 4 (PRG4/lubricin) is secreted by cells that reside in articular cartilage and line the synovial joint. Lubricin may play a role in modulating inflammatory responses through interaction with CD44. This led us to examine if lubricin could be playing a larger role in the modulation of inflammation/immunity through interaction with Toll-like receptors (TLRs). Human Embryonic Kidney (HEK) cells overexpressing TLRs 2, 4 or 5 and surface plasmon resonance were employed to determine if full length recombinant human lubricin was able to bind to and activate TLRs. Primary human synovial fibroblasts were also examined using flow cytometry and Luminex multiplex ELISA. A rat destabilization model of osteoarthritis (OA) was used to determine if lubricin injections were able to regulate pain and/or inflammation in vivo. Lubricin can bind to and regulate the activity of TLRs, leading to downstream changes in inflammatory signalling independent of HA. We confirmed these findings in vivo through intra-articular injections of lubricin in a rat OA model where the inhibition of systemic inflammatory signaling and reduction in pain were observed. Lubricin plays an important role in regulating the inflammatory environment under both homeostatic and tissue injury states.

Denervation impairs healing of the rabbit medial collateral ligament.

Little is known about the contribution of innervation to ligament healing after traumatic disruption, although there is good evidence of an important role for the peripheral nervous system in the healing of fractures and skin injuries. Tissues such as ligament, with a low resting blood supply, are dependent on substantial increases in blood flow and vascular volume during the initial stages of repair. We hypothesized that this initial healing response would be strongly promoted by neurogenic inflammation. Since the saphenous nerve (a major sensory branch of the femoral nerve) supplies the medial half of the knee joint, we elected to use femoral nerve transection as a model to determine the role of sensory and autonomic innervation in the initial outcome of repair of the injured medial collateral ligament. Twelve adult, female NZW rabbits underwent right medial collateral ligament transection. Of these, six rabbits underwent right femoral nerve transection to disrupt the somatic sensory and autonomic nerve supply to the knee joint and six were kept neurologically intact (controls). At six weeks post-injury, the animals were assessed by laser Doppler perfusion imaging (LDI) to determine the local blood flow, at both the injury site and at the uninjured contralateral ligament. The animals were then killed, the knee joints were removed and the biomechanical characteristics of the healing bone-median collateral ligament (MCL)-bone complexes assessed. In a separate cohort of 16 rabbits, vascular volumes of the injured ligaments were measured by infusion of a carmine red/gelatin solution. At six weeks post-injury, in vivo measurement of perfusion with LDI revealed that normally innervated ligaments had an almost three-fold higher average blood flow. Carmine red/gelatin infusion revealed a 50% higher density of blood vessels as compared to denervated ligaments. The force required for ultimate failure was found to be 50% higher in normally innnervated MCL's as compared to denervated MCL's: 153.14 +/- 20.71 N versus 101.29 +/- 17.88 N (p < 0.05). Static creep was increased by 66% in denervated MCL's: 2.83 +/- 0.45% versus 1.70 +/- 0.12% (p < 0.05). Total creep was increased by 45% in denervated MCL's: 5.29 +/- 0.62% compared to 3.64 +/- 0.31% in innervated MCL's (p < 0.05). We conclude that intact innervation makes a critical contribution to the early healing responses of the MCL of adult rabbits.

Vascular response of the meniscus to injury: effects of immobilization.

Failed meniscal healing may lead to degenerative osteoarthritis of the knee. Healing is thought to be dependent upon an adequate blood supply, yet "normal" vascular changes during healing are not well understood. In this study we have quantified vasoactive and angiogenic responses to medial meniscal injury in a rabbit model under clinically relevant conditions, and related these to histological criteria of healing. Twenty-six adult rabbits were given a standardized meniscal injury; 12 of these had the hind limb immobilized by pinning. Eight normal controls and 12 sham-operated animals were also studied. After 4 weeks, animals underwent either vascular volume (vascular index) determination, or blood flow measurement using coloured microspheres. Histological analysis was also performed to assess meniscal healing. In injured animals, blood flow to the menisci was increased fivefold 4 weeks post-operative; this increase was prevented by immobilization. The vascular index of the menisci was also increased threefold by injury, but not significantly reduced by immobilization. Histological examination of injured menisci showed examples of healing and non-healing tears in both mobile and immobile groups. Meniscal injuries are associated with characteristic changes in vascularity and perfusion, and these changes likely play a significant role in the healing process. Characterization of the vascular responses to meniscal injury may lead to techniques that can promote reliable healing of meniscal tears and thereby improve clinical outcomes.

Prone position endoscopic transthoracic release with simultaneous posterior instrumentation for spinal deformity: a description of the technique.

STUDY DESIGN: A prospective series of 15 consecutive adult patients with spinal deformity who underwent endoscopic transthoracic release with simultaneous posterior instrumentation while positioned prone. OBJECTIVES: To describe the technique and clinical results of endoscopic transthoracic release performed with the patient prone (as opposed to lateral) on the concave side for scoliosis or on either side for kyphosis, with simultaneous posterior exposure, instrumentation, and correction of the deformity. SUMMARY OF BACKGROUND DATA: Use of endoscopic surgical techniques is rapidly advancing across all subspecialties. These techniques can be used to expose and operate on the spine in a less invasive fashion, thus avoiding damage to other tissues and facilitating earlier mobilization and rehabilitation. Current endoscopic techniques with the patient in the lateral decubitus position mimic open thoracotomy. A new technique is described with the patient positioned prone, which allows simultaneous posterior exposure. METHODS: Preoperative Cobb angle or thoracic kyphosis angle, maximal correction bending films, and postoperative Cobb angle or kyphosis angle were measured and compared. All perioperative morbidity, intraoperative complications, and surgical variables were prospectively documented and analyzed. RESULTS: There were no intraoperative technical problems with the endoscopic equipment or instruments and no immediate, 6-month, or 2-year postoperative complications related to the endoscopic component of the procedure. In the scoliosis patients, the average correction was 60%. In the kyphosis patients, the average correction was 39%. CONCLUSIONS: Transthoracic endoscopic techniques, compared with thoracotomy, offer a less invasive method of accessing the anterior spinal column, with the benefits of an excellent view of the area of the spine being instrumented, minimal soft tissue disruption, and an improved cosmetic result. With the simultaneous technique, staged or subsequent procedures can be eliminated, and a circumferential structural release as well as control of the mobilized spine can be achieved. This simultaneous technique can be extended for use in correction of a variety of thoracic spinal pathologies.

Transperitoneal laparoscopic exposure for lumbar interbody fusion.

STUDY DESIGN: A prospective clinical trial of the transperitoneal laparoscopic approach to the lumbar spine in a consecutive series of patients undergoing anterior lumbar interbody fusion. OBJECTIVES: To determine safety and effectiveness, and to document technique and perioperative complications of a laparoscopic exposure for lumbar interbody fusion. SUMMARY OF BACKGROUND DATA: With the widespread adoption of laparoscopic techniques, the benefits of minimal access surgery are now well recognized--in general, gynecologic and urologic surgery. Only recently have minimal access techniques been applied to spinal procedures. METHODS: Forty-seven patients with symptomatic degenerative disc disease underwent transperitoneal laparoscopic exposure of the lumbar spine to facilitate implantation of cylindrical threaded interbody fusion cages. These patients were prospectively followed and all perioperative considerations and complications were documented and analyzed. The surgical technique of laparoscopic exposure will be described. RESULTS: The laparoscopic approach was attempted in 47 consecutive patients. Forty-four were completed laparoscopically--36 single level fusions, seven two level fusions, and one three level fusion. Early in the series, conversion to open surgery was required in one patient (case #3) because of bleeding from the presacral veins which hindered the view. In one case, mobilization of the great vessels proved to be difficult, and in one other case the patient could not tolerate abdominal insufflation. The mean blood loss for the entire group was 105 mls. Complications related to the endoscopic exposure were few. There were no injuries to major vascular structures or to bowel, and no mortalities. In two patients, the cages were malpositioned necessitating repeat endoscopic exposure for cage realignment. One patient required a laparotomy for a postoperative small bowel obstruction. The median postoperative stay was 4 days. CONCLUSIONS: Transperitoneal laparoscopic exposure for single or multiple level, anterior lumbar interbody fusion can be performed with low risk. Experience in open anterior spinal surgery and laparoscopic general surgery is vital in minimizing the risks.

Quantitative analysis of the sympathetic innervation of the rat knee joint.

Retrograde tracing with Fluoro-Gold (FG) was used to identify the complete population of knee joint sympathetic postganglionic efferents in the lumbar sympathetic chain of adult female Wistar rats. In 6 rats, the total number and distribution of FG-labelled neurons in the lumbar sympathetic chain was determined. The rat knee joint is supplied by an average of 187+/-57 sympathetic afferents with the majority at the L3 and L4 levels. Immunohistochemistry using antibodies specific for tyrosine hydroxylase (TH), somatostatin (SS) or vasoactive intestinal polypeptide (VIP) revealed that 33 % of knee joint sympathetic afferents contained TH, 42 % contained VIP, and none contained somatostatin. Retrograde tracing with FG provided accurate and reproducible labelling of the joint-innervating subpopulation of sympathetic efferent neurons. This model lends itself to the further study of the molecular responses of this neuronal population in the various disorders and conditions affecting joints.

Atlantoaxial instability complicating radiation therapy for recurrent nasopharyngeal carcinoma. A case report.

STUDY DESIGN: A case report of a patient in whom atlantoaxial instability developed secondary to repeat radiation therapy for recurrent nasopharyngeal carcinoma. OBJECTIVES: To illustrate a dramatic and previously unreported complication of local radiation to the posterior nasopharynx. SUMMARY OF BACKGROUND DATA: Nasopharyngeal carcinoma is an unusual tumor that usually is managed with local, external-beam radiation. It is not thought to involve the cervical spine directly, although local invasion of the skull base is common. METHODS: A review of the medical records and radiographs of the only patient known to develop this complication of radiation used to manage nasopharyngeal carcinoma. RESULTS: Atlantoaxial instability developed in a patient as a result of repeat radiation for a locally recurrent tumor. The instability was associated with intrusion of the anterior arch of C1 into the posterior nasopharynx and was managed successfully with a posterior stabilization using transarticular screws and supplemental wiring. CONCLUSIONS: Patients who have undergone local irradiation for nasopharyngeal carcinoma may be at risk for developing atlantoaxial instability.

Selective ablation of rat knee joint innervation with injected immunotoxin: a potential new model for the study of neuropathic arthritis.

Neuropathic arthropathy is a severe chronic degenerative condition associated with decreased or absent sensory innervation of the involved joint. Existing animal models of neuropathic arthritis are limited by the technical difficulties of obtaining either highly selective or complete joint denervation in a minimally invasive fashion. We undertook experiments to determine the feasibility of using the newly described method of selective neuronal lesioning with injected immunotoxin as a means of creating a more tractable model of neuropathic arthritis. Retrograde tracing with fluorochrome revealed that the knee joint of the female Wistar rat is supplied by 581 +/- 31 (mean +/- SD) joint afferents. Immunohistochemistry confirmed that virtually all sensory neurons in the rat express the cell surface receptor Thy 1. Injection of rat knee joints with an immunotoxin targeted toward Thy 1 resulted in the selective ablation of an average of 88% of the joint afferents identified with fluorochrome that are normally found in the ipsilateral L3 and L4 ganglia.

Number, distribution and neuropeptide content of rat knee joint afferents.

Retrograde tracing with Fluoro-Gold was used to identify the complete population of knee joint afferents in the lumbar dorsal root ganglia of adult female Wistar rats. There was an average of 581 +/- 31 (mean +/- S.D.) afferents supplying each joint. These were found distributed from L1 to L5 with the great majority localised in the L3 and L4 ganglia. Electron microscopy of the posterior articular nerve of the knee revealed an average of 103 +/- 15 (mean +/- S.D.) myelinated and 513 +/- 39 unmyelinated axonal profiles. Since about 50-60% of the unmyelinated profiles would be expected to be sympathetic efferents, these numbers are consistent with the numbers of afferents found by Fluoro-Gold retrograde tracing and suggest that the posterior articular nerve contains about 50% of the total number of knee joint afferents in the rat. Immunohistochemistry revealed that an average of 10% of identified joint afferents expressed substance P-like immunoreactivity and that 33% expressed calcitonin gene-related peptide-like immunoreactivity.

Talar neck fracture with talar head dislocation and intact ankle and subtalar joints: a case report.

The authors describe a rare case of fracture of the neck of the talus associated with talonavicular dislocation but no disruption of the ankle and subtalar joints. The fracture united after open reduction and internal fixation. The head of the talus revealed avascular necrosis but the body did not. A literature review retrieved one previous report of a similar injury, but it was open and became infected. The unique features of this injury pattern and its specific complication, isolated avascular necrosis of the talar head, are discussed.

Age-related loss of knee joint afferents in mice.

Previous work in our laboratory revealed markedly different rates of age-related death of four monoaminergic neuronal populations in the C57BL/6 mouse. Although dorsal root ganglion neurons (DRGns) have been reported not to suffer similar age-related death in rodents, we determined if there is age-related death of the subpopulation of DRGns innervating the knee joints of C57BL/6 mice, which are known to develop degenerative arthritis with aging. The somata of dorsal root ganglion neurons innervating the mouse knee joint (KJ-DRGns) were identified by retrograde tracing with Fluoro-Gold (FG). Lumbar ganglia were serially sectioned and the numbers of FG-labelled KJ-DRGns counted at five ages encompassing the animal's life span. Changes in size of the total population of lumbar DRGns (L-DRGns) were estimated by counting nucleated somata from every fifth toluidine blue-stained serial section from the L3 and L4 lumbar ganglia at three different ages. Using a computer-assisted video morphometric technique somal areas were measured from random sections to determine the distribution of sizes of neurons in the KJ-DRGn and general lumbar DRGn populations at different ages. Counts of FG-labelled joint afferents were 238.5 +/- 80.3 (mean +/- SD) KJ-DRGns per knee at 2 months of age, declining to 103.2 +/- 20.1 by 24 months, representing a 57% loss over the average life span of the C57 mice. The loss occurred in two phases, with a rapid rate over the first 8 months of life and a more moderate rate of loss over the remaining months. L-DRGn numbers revealed a slower overall rate of loss in comparison to the KJ-DRGn population with an average 33.7% loss over the life span of this mouse. Somal size measurements revealed that the larger sizes of KJ-DRGns were lost over the first 8 months of life, with little change in the distribution of somal sizes thereafter. The distributions of sizes of the L-DRGn population did not change significantly over the life spans of the mice. The data provides evidence that the age-related loss of KJ-DRGns is significantly greater than DRGns in general, and may be particularly apparent in the population of larger sized presumed mechanoreceptor neurons. The loss of the KJ-DRGns is approximately reciprocal to the incidence rate of knee joint osteoarthritis reported for the C57BL/6 mice.

Deprenyl reduces the death of motoneurons caused by axotomy.

Deprenyl, a monoamine oxidase B inhibitor, appears to slow the progression of neurological deficits in Parkinson's disease and cognitive decline in Alzheimer's disease. The mechanisms for the slowing of the diseases are unknown. Deprenyl can reduce the death of murine substantia nigra neurons when administered after the neurons are damaged in MPTP parkinsonism by increasing the neurons' survival after they are damaged, rather than by just protecting the neurons against damage by blocking the conversion of MPTP to its active form as was previously thought. The death of immature motoneurons after separation from their muscle targets by axotomy provides a model for assessing trophically dependent neuronal survival. To determine whether deprenyl can alter the survival of neurons other than those in the substantia nigra, we examined the survival of rat facial motoneurons after axotomy at 14 days of age. Using a combination of immunocytochemistry for choline acetyl transferase and Nissl staining, we found that deprenyl treatment (10 mg/kg every second day) increased by 2.2 times the number of motoneurons surviving 21 days after the axotomy. This finding showed that deprenyl treatment can rescue neurons other than those in the substantia nigra and can compensate in part for the loss of target-derived trophic support caused by axotomy.

Interactions between MPTP-induced and age-related neuronal death in a murine model of Parkinson's disease.

Abiotrophy is hypothesized to explain the onset and time course of deficits in Parkinson's disease (PD) Abiotrophy includes: 1) exposure to agent(s) causing the death of dopaminergic nigrostriatal neurons (DNSns), 2) gradual death of DNSns with age, 3) summation of 1) and 2) until DNSn numbers fall below a threshold for detectable neurological deficits. Murine DNSn death following methyl-phenyl-tetrahydropyridine (MPTP) exposure occurs according to an exponential relationship while age-related death of DNSns occurs according to a second exponential relationship. Summing the two exponential losses overestimates experimental DNSn death showing a simple abiotrophic model is not sufficient. Aged murine DNSns greatly increase their dopamine synthesis and the density of their striatal axon terminals which may explain the above threshold. Murine DNSns die gradually after MPTP exposure and L-deprenyl treatment rescues MPTP-damaged DNSns by a previously undiscovered action, altering the abiotrophic interactions and possibly explaining the slowed progression of PD found with deprenyl treatment.

Transmitter synthesis increases in substantia nigra neurons of the aged mouse.

Striatal dopamine concentrations are relatively well maintained with age despite extensive death of the nigrostriatal neurons whose terminals contain the dopamine. Counts of nigrostriatal dopaminergic neurons in C57BL mice identified using immunocytochemistry, Fluoro-Gold retrograde axonal transport and Nissl staining were combined with measures of striatal dopamine and DOPA after saline, pargyline or NSD-1015 treatment. On average, 68% of the dopaminergic nigrostriatal neurons died between ages 8 and 104 weeks and there was a 3-fold increase in dopamine synthesis per average neuron in the aged mice. Increased transmitter synthesis by surviving neurons may serve to compensate brain function in old age.