Prevention of heterotopic ossification after spinal cord injury with COX-2 selective inhibitor (rofecoxib)

STUDY DESIGN

A randomized, prospective, double-blind, placebo-controlled clinical trial.

OBJECTIVES

To determine the effect of COX-2-selective inhibitor on the prevention of heterotopic ossification (HO) after spinal cord injury (SCI).

SETTING

County and University Teaching Hospital, Miami, FL, USA.

METHODS

A total of 76 patients were enrolled in the study. Among them, 39 patients received placebo, and 37 received COX-2-selective inhibitor rofecoxib 25 mg daily for a period of 4 weeks. Prevention was started 3 weeks after spinal cord injury (SCI). In both groups of patients there was similar age as well as the level of SCI and ASIA impairment scale. Two methods were used to diagnose early HO, clinical symptoms and bone scintigraphy. Radiography was used for diagnosis of late stages of HO development.

RESULTS

A significantly lower incidence of HO was found in the rofecoxib group (13.4%) than in the placebo group (33.3%: P<0.05). In patients receiving rofecoxib, there was a 2.5 times lower relative risk of developing HO than in the placebo group (95% CI, 2.3-6). There were no patients who discontinued the study due to adverse effects of medication.

CONCLUSION

Our data suggest that COX-2-selective inhibitor rofecoxib is an effective medication in prevention of HO after SCI.

Long-term regulation of N-methyl-D-aspartate receptor subunits and associated synaptic proteins following hippocampal synaptic plasticity

Synaptic plasticity in the dentate gyrus is dependent on activation of the N-methyl-D-aspartate (NMDA)-subtype of glutamate receptors. In this study, we show that synaptic plasticity in turn regulates NMDA receptors, since subunits of the NMDA receptor complex are bidirectionally and independently regulated in the dentate gyrus following activation of perforant synapses in awake animals. Low-frequency stimulation that produced a mild synaptic depression resulted in a decrease in the NMDA receptor subunits NR1 and NR2B 48 h following stimulation. High-frequency stimulation that produced long-term potentiation resulted in an increase in NR1 and NR2B at the same time point. Further investigations revealed that in contrast to NR2B, NR1 levels increased gradually after long-term potentiation induction, reaching a peak level at 48 h, and were insensitive to the competitive NMDA receptor antagonist 3-3(2-carboxypiperazin-4-yl) propyl-1-phosphate. The increased levels of NR1 and NR2B at 48 h were found associated with synaptic membranes and with increased NMDA receptor-associated proteins, postsynaptic density protein 95, neuronal nitric oxide synthase and Ca(2+)/calmodulin-dependent protein kinase II, alpha subunit. These data suggest that the persistence of long-term potentiation is associated with an increase in the number of NMDA receptor complexes, which may be indicative of an increase in synaptic contact area.

Stimulation-induced reset of hippocampal theta in the freely performing rat

Previous research has suggested that visual and auditory stimuli in a working memory task have the ability to reset hippocampal theta, perhaps allowing an organism to encode the incoming information optimally. The present study examined two possible neural pathways involved in theta resetting. Rats were trained on a visual discrimination task in an operant chamber. At the beginning of a trial, a light appeared over a centrally located lever that the rat was required to press to receive a water reward. There was a 30-s intertrial interval before the next light stimulus appeared. After learning the task, all rats received surgical implantation of stimulating electrodes in both the fornix and the perforant path and recording electrodes, bilaterally in the hippocampus. After surgery, theta was recorded before and after the light stimulus to determine whether resetting to the visual stimulus occurred. During the intertrial interval, rats received single-pulse electrical stimulation of either the fornix or perforant path. Theta was recorded both before and after the electrical stimulation to determine whether resetting occurred. In this experiment, hippocampal theta was reset after all three stimulus conditions (light, perforant path, and fornix stimulation), with the greatest degree of reset occurring after the fornix stimulation. The results suggest that activation of the perforant path and fornix may underlie theta reset and provide a mechanism by which the hippocampus may enhance cognitive processing.

ERK inhibition attenuates 5-HT-induced contractions in fetal and adult ovine carotid arteries

Growth and differentiation-related pathways are much more active in immature than in mature, fully differentiated smooth muscle. Because mitogen-activated protein kinases (MAPK) are intimately involved with growth and differentiation, and the extracellular signal-regulated kinase (ERK) subfamily of MAPKs are involved in some contractile responses, the present studies examined the hypothesis that ERKs play an important and age-dependent role in smooth muscle contraction. The MAPK inhibitors PD098059 and UO126 both inhibited serotonin (5-HT) concentration-response relations more effectively in carotid arteries from term fetal lambs, than in corresponding arteries from mature non-pregnant adult sheep. This inhibition involved significant decreases in both the pD2 (adult: 2-fold; fetus: 4- to 15-fold) and the maximum efficacy (adult: 15-19%; fetus: 34-39%) of 5-HT. Accompanying this age-dependent effect on contraction, quantitative Western blot assays revealed that ERK1 and ERK2 abundances were 39% and 164% greater, respectively, in fetal than in adult carotid arteries. The abundance of the putative ERK target, caldesmon, however, was about 7-fold greater in adult than in fetal arteries. Together, the present results support the view that ERK abundance and activity is upregulated in fetal relative to adult arteries, and that one consequence of this upregulation is that the contribution of ERKs to contraction, at least that initiated by 5-HT2a receptors, is greater in fetal than adult carotid arteries. Whereas the phosphorylation mechanisms through which ERKs augment contraction remain uncertain and controversial, the present results suggest that emphasis should be shifted away from caldesmon and toward other critical contractile proteins, and how these proteins may contribute differently to development of agonist-induced contractile force in immature and mature arteries.

The effects of hyaluronic acid on fibronectin fragment mediated cartilage chondrolysis in skeletally mature rabbits

OBJECTIVE

Intraarticular Na-Hyaluronate (HA) exerts a beneficial effect on adolescent rabbits after fibronectin fragment (Fn-f) mediated cartilage injury. We extended our studies to a population of rabbits which have reached full skeletal maturity.

DESIGN

Adult male NZW rabbits received an injury with Fn-f and no further treatment; an injection of HA followed by Fn-f injury, or Fn-f injury followed by a single or weekly intraarticular injection of HA. All animals were sacrificed 38 days after receiving the Fn-f injury. After sacrifice, proteoglycan (PG) content was determined from articular cartilage from the medial femoral condyles and tibial plateaus. The patellae were processed for histology.

RESULTS

Cartilage PG contents were significantly reduced after Fn-f injection (P=0.0167) and were only slightly improved with HA pre-treatment. However, post-treatment with HA resulted in significant improvements in cartilage PG content when compared to Fn-f only (single HA, P=0.01; weekly HA,P =0.01). Loss of Safranin-O staining, cell loss, osteophyte formation and inflammation were present in the patellae following Fn-f injection. Pre-treatment with HA reduced these changes. More significant protection of cartilage and restoration of Fn-f injury were noted in animals receiving post-treatment with HA.

CONCLUSIONS

These results suggest that 38 days after Fn-f injury the lost PG content induced by Fn-f injection is substantially restored by weekly post-treatment with intraarticular HA in rabbits that have reached full skeletal maturity.

Early alterations in the collagen meshwork and lesions in the ankles are associated with spontaneous osteoarthritis in guinea-pigs

OBJECTIVE

The purpose of this study was to evaluate matrix changes in knee cartilage prior to development of surface disruptions and to examine the ankle for evidence of osteoarthritis (OA)-like lesions.

DESIGN

Guinea-pig ankles and knees were examined histologically or viewed with polarization microscopy to reveal changes in orientation of the collagen fibers.

RESULTS

The medial femoral condyles were virtually free of histologic changes at 3 months of age. Changes were present by 6 months. Medial tibial plateau histologic changes were seen at 3 months which became more pronounced with age. Alterations in the collagen meshwork corresponding to areas of proteoglycan (PG) loss were noted in animals with an intact articular surface as early as 3 months. Histologic changes were noted in the ankles as early as 3 months of age which included surface disruptions, cell loss and loss of PG staining. Only knee joint composite histology scores were significantly elevated at 3 months while both knee and ankle scores were significantly elevated at 6 months. Knee and ankle joint scores were not different from each other at 6 months.

CONCLUSIONS

Alterations in the orientation of the collagen network of the cartilage correlated with Safranin-O loss suggesting that alterations in collagen:PG interactions play a role in the early phases of the OA process and precede frank histologic changes in the articular surface. The results in this study report for the first time OA-like lesions occurring spontaneously in articular cartilage of the ankle in the guinea-pig.

Oropharyngeal stick injury in a Bengal cat

A 16 month old cat presented with a history of acute onset oral pain and hypersalivation. Oral examination revealed a wooden stick that protruded from the right sublingual region. Lateral cervical radiography showed retro pharyngeal gas lucencies. An 11 cm wooden stick was removed per os and the resulting tract was endoscopically explored. There were no post-operative complications and the cat remains disease free four months after presentation. In contrast to dogs, where oropharyngeal stick injuries are an uncommon albeit well recognised condition, there have been no previous case reports of oropharyngeal stick injuries in the cat. This case report describes the presentation, diagnosis and treatment of an oropharyngeal stick injury in a cat.

Overexpression of neurotrophin-3 in skeletal muscle alters normal and injury-induced limb control

Transgenic overexpression of neurotrophin-3 (NT-3) in mice increases the number of surviving proprioceptive sensory components, including primary sensory neurons, gamma motoneurons and muscle spindles. The numbers of surviving alpha motoneurons are not affected by NT-3 overexpression (Wright et al., Neuron 19: 503-517, 1997). We have assessed the consequences NT-3-stimulated increase in the proprioceptive sensory system by measuring locomotive abilities of mice that overexpress NT-3 in all skeletal muscles (myo/NT-3 mice). In adulthood, one myo/NT-3 transgenic line continues to express NT-3 at high levels in muscle and maintains a hypertrophied proprioceptive system (high-OE myo/NT-3 mice). Compared to wildtypes, high-OE myo/NT-3 mice have nine times the amount of NT-3 protein in the medial gastrocnemius at six weeks of age. Although appearing normal during ordinary activity, high-OE myo/NT-3 mice display a distinct clasping phenotype when lifted by the tail. High-OE myo/NT-3 mice show severe locomotor deficits when performing beam walking and rotorod testing. These mice also demonstrate aberrant foot positioning during normal walking. However, following sciatic nerve crush, overexpression of NT-3 prevents further abnormalities in paw positioning, suggesting NT-3 may attenuate sensorimotor deficits that occur in response to sciatic nerve injury. Our results suggest that increases in proprioceptive sensory neurons, spindles and gamma motoneurons, along with continued postnatal NT-3 overexpression in muscle significantly disrupt normal locomotor control. Importantly, however, NT-3 may lessen initial deficits and thus improve functional recovery after peripheral nerve injury, suggesting these mice may serve as a good model to study NT-3's role in neuroprotection of proprioceptive afferents.

Effective problem solving in suicide attempters depends on specific autobiographical recall

The relationship between over-general autobiographical memory and interpersonal problem solving was investigated by comparing a group of suicide attempters with a nonsuicidal psychiatric control group and a normal control group. Results showed that suicide attempters were more over-general in memory and displayed significantly poorer problem solving than the other two groups. Furthermore, suicide attempters who were more over-general displayed greater deficits in problem solving. It was concluded that effective problem solving in suicide attempters depends on specific autobiographical recall.

The effect of bone remodeling inhibition by zoledronic acid in an animal model of cartilage matrix damage

OBJECTIVE

The purpose of this work was to test the effect of inhibition of bone remodeling, through the use of the bisphosphonate, zoledronic acid, on cartilage matrix damage in an animal model of cartilage matrix damage.

DESIGN

New Zealand white rabbits were divided into four groups for treatment purposes: (1) untreated controls; (2) injected into one knee joint with the cartilage matrix degradation enzyme, chymopapain; (3) injected into one knee joint with chymopapain and also given subcutaneous injections of the bisphosphonate, zoledronic acid, three times per week until sacrifice at either day 28 or 56 post-chymopapain-injection; (4) received only the zoledronic acid injections. At sacrifice, the knee joints were examined grossly and histologically, and biochemically for proteoglycan content. Urine samples were analysed, at intervals, for levels of collagen cross-links which are biochemical markers of cartilage and bone.

RESULTS

Animals receiving both intraarticular chymopapain injections and subcutaneous zoledronic acid injections displayed a significantly lower degree of grossly and histologically detectable cartilage degeneration on the tibial articular surfaces (the articular surface displaying the greatest degree of degeneration) than did animals only receiving the chymopapain injections. In addition, urinary levels of collagen cross-links for bone and cartilage were significantly higher in those animals only receiving chymopapain injections.

CONCLUSION

The bone resorption observed after chymopapain injection into the rabbit knee joint can be inhibited through the use of the bisphosphonate, zoledronic acid. Furthermore, zoledronic acid does not increase the level of cartilage degeneration and appears to provide some level of chondroprotection in this model.

Muscle-derived neurotrophin-3 reduces injury-induced proprioceptive degeneration in neonatal mice

During perinatal development, proprioceptive muscle afferents are quite sensitive to nerve injury. Here, we have used transgenic mice that overexpress neurotrophin-3 (NT-3) in skeletal muscle (myo/NT-3 mice) to explore whether NT-3 plays a neuroprotective role for perinatal muscle afferents following nerve injury. Measurements of NT-3 mRNA using RT-PCR revealed that levels of endogenous NT-3 mRNA in wild-type muscles remained constant during the first postnatal week following nerve crush or nerve section on postnatal day (PN) 1. In comparison, myo/NT-3 mice had significantly elevated levels of NT-3 mRNA that were maintained or increased following injury. To assess whether muscle-derived NT-3 could prevent injury-induced neuronal death, neuron survival in the DRG was analyzed in mice 5 days after sciatic nerve crush on PN3. Retrograde prelabeling of muscle afferents and parvalbumin immunocytochemistry both revealed that overexpression of NT-3 in muscle significantly reduced neuronal loss following injury. Similar neuroprotective effects of NT-3 were observed in wild-type mice injected with exogenous NT-3 in the gastrocnemius muscles. To test whether NT-3 could prevent muscle spindle degeneration, spindle number and morphology were assessed 3 weeks after sciatic nerve crush or section on PN1. No spindles were present in either wildtype or myo/NT-3 muscles after nerve section, demonstrating that NT-3 overexpression cannot maintain spindles following complete denervation. Moreover, NT-3 overexpression could not prevent moderate spindle loss in muscle and did not stimulate new spindle formation following nerve crush. Our results demonstrate that in addition to its early actions on sensory neuron generation and naturally occurring cell death, NT-3 has important neuroprotective effects on muscle afferents during postnatal development.

Effects of maturation on mechanisms of cGMP-induced cerebral vasodilatation

In light of observations that cerebrovascular levels of cGMP vary during maturation, the present study examines the possibility that the mechanisms mediating cGMP-induced cerebral vasodilatation also change during maturation. Specifically, these experiments explore age-related changes in the ability of cGMP to both: (1) depress cytosolic calcium concentration, and (2) attenuate contractile protein calcium sensitivity in alpha-toxin and beta-escin permeabilized preparations as well as fura-2 loaded arteries. The present data demonstrate that: (1) cGMP attenuates cytosolic calcium concentration at lower concentrations than required to reduce myofilament calcium sensitivity; (2) both potassium-induced and 5HT-induced contractions were more sensitive to cGMP in fetal than adult arteries; (3) all potassium-induced increases in cytosolic calcium were resistant to the effects of cGMP, but those produced by 5HT were sensitive to attenuation by cGMP, and more so in fetal than in adult basilar arteries, and (4) cGMP attenuated both basal and agonist-enhanced myofilament calcium sensitivity. Overall, these data demonstrate that the mechanisms mediating the multiple vasoactive effects of cGMP are more potent in immature than in mature cerebral arteries and are heavily influenced by both the artery type and the method of contraction.

Developmental changes in ryanodine- and IP(3)-sensitive Ca(2+) pools in ovine basilar artery

To explore the hypothesis that cerebrovascular maturation alters ryanodine- and inositol 1,4,5-trisphosphate (IP(3))-sensitive Ca(2+) pool sizes, we measured total intracellular Ca(2+) with (45)Ca and the fractions of intracellular Ca(2+) released by IP(3) and/or caffeine in furaptra-loaded permeabilized basilar arteries from nonpregnant adult and term fetal (139-141 days) sheep. Ca(2+) mass (nmol/mg dry weight) was similar in adult (1.60 +/- 0.18) and fetal (1.71 +/- 0.16) arteries in the pool sensitive to IP(3) alone but was significantly lower for adult (0.11 +/- 0.01) than for fetal (1.22 +/- 0.11) arteries in the pool sensitive to ryanodine alone. The pool sensitive to both ryanodine and IP(3) was also smaller in adult (0.14 +/- 0.01) than in fetal (0.85 +/- 0.08) arteries. Because the Ca(2+) fraction in the ryanodine-IP(3) pool was small in both adult (5 +/- 1%) and fetal (7 +/- 4%) arteries, the IP(3) and ryanodine pools appear to be separate in these arteries. However, the pool sensitive to neither IP(3) nor ryanodine was 10-fold smaller in adult (0.87 +/- 0.10) than in fetal (8.78 +/- 0.81) arteries, where it accounted for 72% of total intracellular membrane-bound Ca(2+). Thus, during basilar artery maturation, intracellular Ca(2+) mass plummets in noncontractile pools, decreases modestly in ryanodine-sensitive pools, and remains constant in IP(3)-sensitive pools. In addition, age-related increases in IP(3) efficacy must involve factors other than IP(3) pool size alone.

Generation of a selective 5-HT3B subunit-recognising polyclonal antibody; identification of immunoreactive cells in rat hippocampus

The present study generated a polyclonal antibody (AP86/3) that recognises a peptide sequence of the h5-HT(3B) receptor subunit. Western blot analysis of homogenates prepared from cell lines expressing either homomeric (h5-HT(3A)) or heteromeric (h5-HT(3A/3B)) receptors, as well as immunocytochemical studies with the same cell lines, indicated that AP86/3 recognised, selectively, the 5-HT(3B) subunit. Immunohistochemical labelling was also apparent in cells in the rat hippocampus that displayed the distribution and morphology of interneurones.

A single injection of fibronectin fragments into rabbit knee joints enhances catabolism in the articular cartilage followed by reparative responses but also induces systemic effects in the non-injected knee joints

OBJECTIVE

To investigate effects on cartilage metabolism and degeneration of injection of fibronectin fragments (Fn-fs) into rabbit knee joints.

DESIGN

The knees of adolescent New Zealand white rabbits were intraarticularly injected with rabbit Fn-fs. Cartilage sections from both injected and non-injected joints were treated with Safranin-O, with antibodies to the VDIPEN and NITEGE neoepitopes of degraded aggrecan and to matrix metalloproteinase-3 (MMP-3). Proteoglycan (PG) content of cartilage was measured by a dimethylmethylene blue assay of papain digests. PG synthesis rates were measured by(35)S-sodium sulfate incorporation into explanted cartilage.

RESULTS

In the injected joint cartilage, the Fn-fs bound cells in the upper superficial zone maximally between 6 and 24 h. By day 2, MMP-3 protein was enhanced and cartilage PG content and PG synthesis rates were reduced 40% and 70%, respectively. MMP-3 epitope and VDIPEN and NITEGE neoepitopes were also enhanced. The PG content then increased to supernormal levels from days 14 to 35 and then declined to normal levels by day 70, as did PG synthesis rates. In the non-injected joint cartilage, Fn-fs were not detected. Although MMP-3 expression was enhanced between days 2 and 21 as well as VDIPEN neoepitope, the PG content was never reduced but rather enhanced to supernormal levels from days 21 to 35. This was associated with enhanced PG synthesis by day 7, which decreased to control levels by day 70.

CONCLUSIONS

In this cartilage degeneration model, loss of cartilage PG is followed by supernormal anabolic responses that facilitate PG restoration. Further, the damage causes a systemic effect of enhanced PG synthesis and content in the non-injected joint cartilage.

Hospital preparedness for weapons of mass destruction incidents: an initial assessment

STUDY OBJECTIVE

We performed an assessment of hospital preparedness for weapons of mass destruction (WMD) incidents in Federal Emergency Management Agency (FEMA) Region III.

METHODS

Interviews of hospital personnel were completed in 30 hospitals. Data collected included level of preparedness, mass decontamination capabilities, training of hospital staff, and facility security capabilities.

RESULTS

No respondents believed their sites were fully prepared to handle a biologic incident, 73% (22/30) believed they were not prepared to manage a chemical weapons incident, and 73% believed they were unprepared to handle a nuclear event. If a WMD incident were to occur, 73% of respondents stated a single-room decontamination process would be set up. Four (13%) hospitals (all rural) reported no decontamination plans. WMD preparedness had been incorporated into hospital disaster plans by 27% (8/30) of facilities. Eighty-seven percent (26/30) believed their emergency department could manage 10 to 50 casualties at once. Only 1 facility had stockpiled any medications for WMD treatment. All facilities had established networks of communication. No hospital had preprepared media statements specific to WMD. Nearly one fourth (7/30) stated that their hospital staff had some training in WMD event management. All reported need for WMD-specific training but identified obstacles to achieving this. Seventy-seven percent (23/30) of hospitals had a facility security plan in place, and half were able to perform a hospital-wide lock down. Ninety-six percent (29/30) reported no awareness regarding the threat of a secondary device.

CONCLUSION

Hospitals in this sample do not appear to be prepared to handle WMD events, especially in areas such as mass decontamination, mass medical response, awareness among health care professionals, health communications, and facility security. Further research is warranted, including a detailed assessment of WMD preparedness using a statistically valid sample representative of hospital emergency personnel at the national level.

The effect of being a victim or witness of family violence on the retrieval of autobiographical memories

OBJECTIVE

This study was designed to determine whether greater reliance on general memory retrieval in children was related to depression, and whether family violence affected the specificity of children's memory retrieval.

METHOD

We compared children who had experienced some form of family violence with children who had never experienced any form of family violence, based on their responses to questions concerning child-parent and interparental disagreements.

RESULTS

As expected, there was a positive correlation between the extent of "generic-categoric" memory retrieval and depression level. There was no evidence, however, that autobiographical memory was affected by family violence.

CONCLUSIONS

This study is the first to report significant associations between depression and autobiographical memory style in children. The results suggest that the effect of family violence on children's memory retrieval may be mediated by depression.

Children's understanding of the physical, cognitive and social consequences of impairments

The present study explored typically developing children's (n = 77) understanding of physical, cognitive and social competencies of children with impairments. Children in each of four age groups (4-5 years, 6-7 years, 9-10 years and 11-12 years) were interviewed to explore their ideas about the abilities of children with physical impairments (minor: missing thumb; major: wheel-chair bound), sensory impairments (vision and hearing), learning disabilities (non-specific and Down's syndrome) and emotional/behavioural difficulties (attention deficit hyperactivity disorder and lack of social skills). Significant age differences were found in children's judgements of the capabilities of children with impairments. Furthermore, children's understanding of the consequences of impairments varied as a function of disability type. Findings are discussed in relation to previous research on children's disability concepts and implications for inclusive education practices.