Should helical CT scanning of the thoracic cavity replace the conventional chest x-ray as a primary assessment tool in pediatric trauma? An efficacy and cost analysis.

BACKGROUND/PURPOSE: Findings from studies in the trauma literature suggest that thoracic computed tomography (TCT) scanning should replace conventional radiographs as an initial imaging modality. Limited data exist on the clinical utility and cost of TCT scans in pediatric trauma. Our current practice is to obtain TCT scans in those children at risk for thoracic injures. The purpose of this study is to examine what additional information TCT provides, how frequently it results in a change in clinical management, and a cost/benefit analysis. METHODS: Children 18 years old and younger that had both a Chest x-ray (CXR) and TCT scan in their initial workup were included. Indications for TCT scan were (1) any sign of thoracic injury on CXR, (2) pathologic findings on physical examination of the chest, and (3) high impact force to chest wall. A child may have had one or more indications for a TCT scan. RESULTS: Between 1996 and 2000, 45 of 1,638 trauma patients met study criteria. Indications for TCT included thoracic injury on CXR (n = 27), findings on physical examination (n = 8) and high-impact force (n = 33). In 18 of the 45 (40%), injuries were detected with TCT imaging but not on CXR. These included contusions (n = 12), hemothorax (n = 6), pneumothorax (n = 5), widened mediastinum (n = 4), rib fractures (n = 2), diaphragmatic rupture (n = 1), and aortic injury (n = 1). In 8 patients (17.7%) TCT imaging resulted in a change in clinical management. These included insertion of a chest tube (n = 5) aortography (n = 2) and operation (n = 1). Age, sex, injury severity score, mechanism, and indication for TCT could not predict differences between TCT and CXR (P >.05). In our institution, the cost of a TCT is $200, and the patient charge is $906 ($94 per CXR). Based on our study data 200 TCTs would need to be done for each clinically significant change, increasing patient ($180,000) and hospital ($39,600) costs. CONCLUSIONS: Helical TCT is a highly sensitive imaging modality for the thoracic cavity; however, routine CXR still provides clinically valuable information for the initial trauma evaluation at minimal cost. TCT should be reserved for selected cases and not as a primary imaging tool.

Distribution of beta-endorphin and substance P in the shoulder joint of the dog before and after a low impact exercise programme.

Beta-endorphin and substance P were immunolocalized in the articular cartilage, synovial membrane and fibrous joint capsule of dogs. Twelve adult greyhounds were randomly assigned to one of three groups: control, limited exercise, or regimented exercise. On day 0, biopsies of articular cartilage and joint capsule were obtained from the left shoulder joints of dogs receiving limited and regimented exercise. On day 72, biopsies of joint capsule from right and left shoulders and articular cartilage from the right shoulder joint were analysed for the presence of glycosaminoglycans (GAG) and for immunolocalization of substance P and beta-endorphin. Regimented exercise increased the presence of GAGs and immunolocalization of substance P and beta-endorphin in articular cartilage and synovial membrane compared to day 0 biopsies and untreated controls. Localization of beta-endorphin became prominent in and around the chondrocytes. Substance P was increased in chondrocytes and extracellular matrix. Concomitant changes in localization of beta-endorphin and substance P may have a role in the modulation of the microphysiological environment, metabolism, or function of joint tissues in response to low-impact exercise.

The discovery of anthranilic acid-based MMP inhibitors. Part 2: SAR of the 5-position and P1(1) groups.

A novel series of anthranilic acid-based inhibitors of MMP-1, MMP-9, MMP-13, and TACE was prepared and evaluated. Selective inhibitors of MMP-9, MMP-13, and TACE were identified, including the potent, orally active MMP-13 inhibitor 4p.

Evaluation of the rat stifle joint after transection of the cranial cruciate ligament and partial medial meniscectomy.

Osteoarthritis (OA) was induced in the rat stifle joint by partial medial meniscectomy (PMM) and transection of the cranial cruciate ligament (CCL). At 10 weeks after destabilization, joint morphologic and pathologic changes were observed, scored, and compared. The intact rat stifle joint was observed in a mid-saggital plane. Articular cartilage of the distal portion of the femur and proximal portion of the tibia had thicker and thinner sites, and the thicker sites were located caudally on the distal portion of the femur and centrally on the proximal portion of the tibia. The two separate triangular portions of the medial meniscus observed in the mid-saggital plane contained a center of ossification in the cranial portion and fibrocartilage in the caudal portion. The synovium was one to three cells thick, and contained rare inflammatory cells. Although lesions were more severe in stifles after PMM, both treatments produced OA lesions that closely simulated OA lesions of other species. Lesions consistent with idiopathic OA included chondrocytic clones with increased metachromasia around them, chondrocytic death, loss of metachromasia, fibrillation, fissuring, erosion of articular cartilage, osteophyte formation, and variable synovial inflammation. The results indicate that PMM and CCL transection in the rat are useful in vivo models for study of the etiopathogenesis of OA and therapeutic efficacy of anti-arthritic drugs and treatment concepts.

Oral treatment with a nutraceutical (Cosequin) for ameliorating signs of navicular syndrome in horses.

Fourteen horses with a progressive forelimb lameness of 3 to 12 months' duration, diagnosed as navicular syndrome, were selected from clinical cases admitted to Auburn University Equine Hospital for evaluation of the efficacy of an orally administered nutraceutical (Cosequin, Nutramax Laboratories, Inc., Edgewood, MD) for ameliorating clinical signs associated with naturally occurring navicular syndrome. Horses were randomly allocated to treatment with the nutraceutical or a placebo. Treatment was five scoops (16.5 g) of powder twice daily in the feed. The test group (n = 8) received a patented nutraceutical consisting of 9 g of FCHG49 (a highly purified glucosamine HCl), 3 g of TRH122 (a specific purified low-molecular-weight sodium chondroitin sulfate), and 600 mg of manganese ascorbate. The placebo group (n = 6) received an indistinguishable oral powder containing only excipients. Owners and the investigator were unaware of group assignments. The same investigator assessed lameness and overall clinical condition at enrollment and after 4 and 8 weeks of treatment. Lameness was assessed by an algofunctional lameness index, comprising a combined sum score of standing posture, hoof tester examination, and lameness scores at various levels of work. Overall clinical efficacy was rated on a visual analogue scale. Owners assessed lameness via a preassigned questionnaire, incorporating an algofunctional lameness index and overall clinical condition at weekly intervals. Radiographic examinations of the navicular bones were performed at enrollment and after 8 weeks of treatment. The median algofunctional lameness index and overall clinical condition scores assigned the investigator were significantly improved (P = .05) for horses treated with the nutraceutical compared with placebo-treated horses. The degree of improvement in algofunctional lameness index assigned by owners after 8 weeks was also significant (P = .045) between the treatment groups. Radiographic scores after treatment were not significantly different between the groups (P > .05).

Human milk contains detectable levels of immunoreactive leptin.

Leptin, the recently cloned product of the obese (ob) gene, is a 16 kDa-protein that acts as a circulating satiety factor. It also serves to regulate energy expenditure and may act as a counter regulatory hormone to insulin. Initially thought to be exclusively produced by mature adipocytes, its mRNA has now been identified in significant levels in the placenta as well as the fetus raising speculation regarding its importance as a growth factor. Given studies demonstrating that exclusively breast-fed infants are leaner due to decreased energy intakes than formula-fed infants, we hypothesized that the presence of leptin in human milk could participate in mediating the earlier satiety of those infants fed human milk. We undertook this initial study to qualitatively examine the presence of leptin in human milk utilizing an immunoblot approach. Random milk samples during the first 2 weeks of lactation were available for study from 4 mothers delivering at term. Milk samples were centrifuged, the aqueous layer removed, and the protein content quantitated. One-hundred micrograms of total protein were separated by sodium dodecyl sulfate-polyacrylamide-gel electrophoresis (SDS-PAGE), transferred to nitrocellulose, and immunoblotted with an antileptin antibody. As controls, recombinant human leptin alone and a sample of milk containing added leptin were similarly electrophoresed and immunoblotted. Labeled proteins were visualized by chemiluminescence. Significant amounts of leptin protein were identified in all milk samples examined. No difference in protein detection was identified in fresh milk vs. frozen milk, and little difference was apparent in foremilk samples vs. hindmilk samples. These preliminary data reveal the presence of leptin in term human milk and suggest that further studies to document bioactivity of milk-derived leptin are warranted.

Immunolocalization analysis of transforming growth factor-beta1 in the growth plates of broiler chickens with high and low incidences of tibial dyschondroplasia.

Immunolocalization of transforming growth factor-beta1 (TGF-beta1) was determined in growth plates of two lines of broiler chickens with low and high incidences of tibial dyschondroplasia (TD). Ultrathin sections of growth plates from each line were treated with a polyclonal antibody specific for TGF-beta1, followed by colloidal gold-labeled protein A. Immunolocalization for TGF-beta1 was observed in chondrocytes of all zones of growth plates of low and high TD incidence lines. However, immunolocalization in extracellular matrix was restricted to the hypertrophic zones of both lines. In the hypertrophic zone of low TD incidence line, immunolocalization of TGF-beta1 in the extracellular matrix adjacent to collapsed cartilage canals (matrix streaks) was significantly greater than immunolocalization between patent cartilage canals. A similar increase was not observed in the high TD incidence line. Results indicate that chondrocytes of all zones of the growth plate contain TGF-beta1 but do not release it into extracellular matrix until hypertrophy has occurred. Greater concentrations of TGF-beta1 adjacent to collapsed cartilage canals may play a role in controlling angiogenesis and directing invasion of mineralized hypertrophic cartilage by metaphyseal blood vessels. A low concentration of TGF-beta1 in the extracellular matrix adjacent to collapsed cartilage canals of the high TD incidence line may be a factor in limiting vascular invasion of dyschondroplastic cartilage of TD lesions.

Low-field magnetic resonance imaging of the equine tarsus: normal anatomy.

The objective of this study was to define the normal gross anatomic appearance of the adult equine tarsus on a low-field magnetic resonance (MR) image. Six radiographically normal, adult, equine tarsal cadavers were utilized. Using a scanner with a 0.064 Tesla magnet, images were acquired in the sagittal, transverse and dorsal planes for T1-weighted and the sagittal plane for T2-weighted imaging sequences. Anatomic structures on the MR images were identified and compared with cryosections of the imaged limbs. Optimal image planes were identified for the evaluation of articular cartilage, subchondral bone, flexor and extensor tendons, tarsal ligaments, and synovial structures. MR images provide a thorough evaluation of the anatomic relationships of the structures of the equine tarsus.

Effects of dietary roxarsone supplementation, lighting program, and season on the incidence of leg abnormalities in broiler chickens.

Two 4 x 2 factorial experiments were designed to test the effects of four diets, differing in anticoccidial programs and roxarsone (3-nitro-4-hydroxyphenylarsonic acid) content, and two lighting programs on the incidence of leg abnormalities in 56-d-old male and female broiler chickens. The four diets were: A) basal diet + salinomycin (60.0 g/ton); B) basal diet + salinomycin (60.0 g/ton) + roxarsone (45.4 g/ton); C) basal diet + roxarsone (45.4 g/ton) + live coccidial vaccine; and D) basal diet + live coccidial vaccine. The light treatments were: 1) restricted (R) [18 h light (L): 6 h dark (D)] and 2) standard (S) [23L:1D]. The respective experiments were conducted during winter (Experiment 1, November to January) and summer (Experiment 2, June to August) growing conditions in the southeastern U.S. Light treatment had no significant (P > 0.10) effect on the incidence of leg abnormalities in either experiment. However, in Experiment 1, there was a light treatment by sex interaction; leg abnormalities were greater for males on Treatment R than Treatment S. In Experiment 2, females had a higher incidence of leg abnormalities than males (8.29 vs 4.73%). There was a diet by sex interaction for the incidence of leg abnormalities in Experiment 2; females had a greater incidence of leg abnormalities than males on Treatment A. In both experiments, the incidence was greater with dietary treatments containing roxarsone (P < 0.10). The percentage of leg abnormalities was greater in Experiment 2 than Experiment 1. Leg abnormalities were primarily due to fibrosis of the gastrocnemius tendons and tendon sheaths.

Effect of hydration on signal intensity of gelatin phantoms using low-field magnetic resonance imaging: possible application in osteoarthritis.

Five gelatin phantoms were constructed to study the effect of matrical hydration on magnetic resonance imaging (MRI) signal intensity using a low-field strength imager. Water content of the phantoms ranged from 75 to 95% weight/weight. Signal intensity values of each phantom were measured using five imaging sequences: proton density, T1-weighted, T2-weighted, inversion recovery with short inversion time, and inversion recovery with long inversion time. There was significant positive correlation (p < .05) of signal intensity with differences in hydration using the T2-weighted sequence and the inversion recovery sequence with short inversion time. Significant negative correlations (p < .05) were found with T1-weighted imaging and the inversion recovery sequence with long inversion time. In a second part of the study, in vivo focal variations in MRI signal intensity were evaluated in a canine cranial cruciate ligament deficient model of osteoarthritis. Signal intensity measurements were obtained from multiple areas of articular cartilage to identify an initial stage in osteoarthritis that is characterized in part by increased hydration of articular cartilage. At 6 weeks post-transection of the cranial cruciate ligament, an increase in signal intensity was detected in the articular cartilage of the weight-bearing portion of the lateral femoral condyle and the caudal portion of the medial tibial condyle with T1-weighted imaging. The increase in signal intensity may reflect increased proteoglycan synthesis by chondrocytes that also occurs early in the pathogenesis of osteoarthritis.

Sensitivity of patients with painful temporomandibular disorders to experimentally evoked pain: evidence for altered temporal summation of pain.

Temporomandibular disorders (TMD) represent a group of chronic painful conditions involving the muscles of mastication and the temporomandibular joint. Several studies have reported that TMD is associated with enhanced sensitivity to experimental pain. Twenty-three TMD subjects and 24 pain-free matched control subjects participated in a set of studies which were designed to evaluate whether the temporal integrative aspects of thermal pain perception are altered in TMD patients compared with control subjects. Specifically, we have examined in both TMD patients and in age- and gender-matched control subjects: (1) the time-course and magnitude of perceived pain evoked by the application of sustained 7-s noxious thermal stimuli (45-48 degrees C) to the face and forearm, (2) the central summation of C-fiber-mediated pain produced by applying brief trains of noxious heat pulses to the skin overlying the ventral aspect of the right palm and (3) the ability to discriminate small increments in noxious heat applied to facial and volar forearm skin. Data collected from these studies indicate that TMD patients show enhanced temporal integration of thermal pain compared with control subjects. TMD patients show greater thermal C-fiber-mediated temporal summation than pain-free subjects and they report a greater magnitude of sustained noxious heat pulses applied to either the face or the forearm than control subjects. In contrast to these findings, TMD and pain-free subjects are equally able to discriminate and detect small increments of heat applied to noxious adapting temperatures. These findings suggest that the augmented temporal integration of noxious stimuli may result from alterations in central nervous system processes which contribute to the enhanced pain sensitivity observed in TMD patients.

Low-field magnetic resonance imaging of early subchondral cyst-like lesions in induced cranial cruciate ligament deficient dogs.

Six healthy adult male mongrel dogs underwent cranial cruciate ligament transection in the left stifle. Survey radiography of both stifles and low-field (0.064 T) MRI of the left stifle were performed preoperatively and at 2, 6, and 12 weeks postoperatively. Focal changes in signal intensity were seen with MRI in the subchondral bone of the medial tibial condyle at 2 and 6 weeks postoperatively. At 12 weeks postoperative, a cyst-like lesion was detected using MRI in the subchondral bone of the medial tibial condyle in 4 of 6 dogs and a less defined lesion at this site in the remaining 2 dogs. The cyst-like lesion was spherical in shape and showed typical characteristics of fluid with low signal intensity on T1-weighted images, high signal intensity on T2-weighted images and high signal intensity on inversion recovery images. The lesion was seen in the subchondral bone of the caudal medial and/or middle region of the tibial plateau slightly cranial to the insertion of the caudal cruciate ligament. No subchondral cysts were seen in the tibia on radiographs. Histopathologically, the tibia was characterized by a loose myxomatous phase of early subchondral cyst formation.

Low-field magnetic resonance imaging of the canine stifle joint: normal anatomy.

Low-field magnetic resonance imaging (MRI) was performed on the stifle joints of four normal adult mongrel dogs using a 0.064 Tesla scanner. Markers were placed on each stifle joint to serve as reference points for comparing gross sections with the images. A T1-weighted sequence was used to image one stifle joint on each dog in the sagittal plane and the other stifle joint in the dorsal plane. The dogs were euthanized immediately following MRI and the stifle joints frozen intact. Each stifle joint was then embedded in paraffin, again frozen, and sectioned using the markers as reference points. On T1-weighted images, synovial fluid had low signal intensity (dark) compared to the infrapatellar fat pad which had a high signal intensity (bright). Articular cartilage was visualized as an intermediate bright signal and was separated from trabecular bone by a dark line representing subchondral bone. Menisci, fibrous joint capsule, and ligamentous structures appeared dark. In the true sagittal plane, the entire caudal cruciate ligament was often seen within one image slice. The patella was visualized as an intermediate bright signal (trabecular bone) surrounded by a low intensity signal (cortical bone). The trochlea and the intercondylar notch were difficult areas to analyze due to signal volume averaging of the curved surface of these areas and the presence of several types of tissues.

Relationship between pain sensitivity and resting arterial blood pressure in patients with painful temporomandibular disorders.

OBJECTIVE: Patients experiencing temporomandibular disorders (TMD) show greater sensitivity to painful stimuli than age- and gender-matched control subjects. This enhanced pain sensitivity may result, at least in part, from an alteration in pain regulatory systems that are influenced by resting arterial blood pressure. In this study, we examined the relationship between resting systolic blood pressure and pain perception in 64 female TMD and 23 age-matched pain-free female subjects. METHOD: Resting arterial blood pressure and measures of thermal and ischemic pain threshold and tolerance were determined for each participant. Subjective ratings of thermal pain evoked by suprathreshold noxious thermal stimuli (45-49 degrees C) using a magnitude matching procedure were also obtained for both groups. RESULTS: TMD patients had lower thermal and ischemic pain thresholds and tolerances than pain-free subjects (ps < .05). Both groups provided equivalent intensity ratings to suprathreshold noxious thermal stimuli. A median split of each group based on resting systolic blood pressure revealed an influence of blood pressure on both thermal and ischemic pain perception for the Pain-Free group. The Pain-Free high resting blood pressure subgroup had higher thermal pain tolerances, higher ischemic pain thresholds, and provided lower magnitude estimates of the intensity of graded heat pulses compared with the Pain-Free low blood pressure subgroup. A trend toward a significant effect of blood pressure level on ischemic pain tolerance was also observed for the Pain-Free group. In contrast to the Pain-Free group, blood pressure level did not influence ischemic or thermal pain perception for TMD patients. Similar to the lack of effect of resting blood pressure on experimental pain perception in TMD patients, resting blood pressure was not related to measures of clinical orofacial pain in TMD patients. CONCLUSIONS: These findings confirm our previous findings that TMD patients are more sensitive to noxious stimuli and suggest that painful TMD may result, at least in part, from an impairment in central pain regulatory systems that are influenced by resting arterial blood pressure.

Conceptualizing and scaling the developmental structure of behavior disorder: the Lifetime Alcohol Problems Score as an example.

We contrast the current, clinically based framework for behavior disorder against a life course framework, as an alternative structure upon which to map the variations in onset and stability of clinical symptomatology known to take place in adult life. This alternative developmental framework is used as a base around which to understand known variations in rates of alcohol abuse/dependence over the life course and to review existing schemes for the evaluation of developmental variation in "caseness." From this work, it was proposed that symptom structure be regarded as a mass of greater or lesser breadth, with properties of extensiveness in time and life course invasiveness, as a function of where in the life course the symptomatology first emerged, and the degree to which the mass sustained itself in developmental time. This framework guided the construction of a time-based measure of alcohol related symptomatology, called the Lifetime Alcohol Problems Score (LAPS). The LAPS discriminated among a variety of alcohol-specific and nonalcohol-specific measures of alcohol-related difficulty, including diagnosis of alcohol dependence, having been in treatment, level of other psychopathology, and measures of family disorganization. The measure has potential applicability for prospective studies, and in estimating clinical prognosis. The utility of the paradigm as a framework within which to conceptualize the emergence, ebb, and flow of other behavior disorders is also discussed.

Sexual and physical abuse history in subjects with temporomandibular disorders: relationship to clinical variables, pain sensitivity, and psychologic factors.

Recent evidence suggests that a past history of physical and/or sexual abuse is more frequently reported among chronic pain populations; however, the prevalence of reported abuse has not been examined in patients with chronic orofacial pain caused by temporomandibular disorders (TMD). This study compares reported physical/sexual abuse among female TMD subjects recruited from the general population with that of age-matched female control subjects. The association of reported abuse with clinical pain, experimental pain responses, and psychologic variables was examined in the TMD group. Results indicated that a slightly but not statistically greater percentage of TMD subjects (44.8%) reported a history of sexual or physical abuse compared to control subjects (33.3%). Reported abuse among TMD subjects was not related to clinical pain or psychologic variables. Regarding experimental pain responses, TMD subjects reporting a history of abuse exhibited longer ischemic pain tolerances compared to those not reporting abuse; however, the groups did not differ on other experimental pain measures. Results indicate that the reported prevalence of physical/sexual abuse is similar among TMD subjects compared to other chronic pain populations; however, the relationship of abuse to clinical and psychosocial variables remains unclear.

Pain sensitivity in patients with temporomandibular disorders: relationship to clinical and psychosocial factors.

OBJECTIVE: We have previously reported that patients with temporomandibular disorders (TMD) exhibit enhanced sensitivity to experimentally evoked pain (1); however, the clinical relevance of this increased pain sensitivity remains unclear. The purpose of this study was to investigate the relationship of experimental pain sensitivity to clinical and psychosocial variables among patients with TMD. DESIGN: Thirty-six TMD patients were studied, half of whom were pain sensitive (PS) and the other half pain tolerant (PT), based on their ability to tolerate an ischemic pain task. Responses to painful thermal and nonpainful visual stimuli as well as clinical/diagnostic symptoms and psychosocial variables were compared for the two groups (i.e., PS vs. PT). RESULTS: Results indicated that, compared with PT patients, the PS group exhibited greater sensitivity to thermal pain and rated innocuous visual stimuli as more intense. PS patients also reported greater clinical pain, but in general the groups did not differ on diagnostic and psychosocial measures. CONCLUSIONS: The results suggest that ischemic pain tolerance is a clinically relevant marker of pain sensitivity in TMD patients. These findings are consistent with the hypothesis that impairments in CNS inhibitory pathways may contribute to the pain associated with TMD.

Lighting programs for broilers that reduce leg problems without loss of performance or yield.

This study tested the effects of light schedules on performance and yields of broiler chickens. In Experiment 1, light treatments during Days 1 to 49 of age were: 1) 23 h light (L):1 h dark (D); 2) 16L:8D;3) 16L: 3D:1L:4D; and 4) 16L:2D:1L:2D:1L:2D. In Experiment 2, Light Treatments 1 and 2 were the same as Treatments 1 and 4, respectively, in Experiment 1; 3) 23L:1D Days 1 to 7, 16L:8D Days 8 to 14, the light period was increased by 2 h/wk during Days 15 to 35, and 23L:1D Days 36 to 42; and 4) 23L:1D Days 1 to 7, 16L:8D Days 8 to 14, 16L:3D: 2L:3D Days 15 to 21, 16L:2D:4L:2D Days 22 to 28, 16L: 1D:6L:1D Days 29 to 35, and 23L:1D thereafter. In Experiment 1, BW was greater in Treatment 4 than Treatment 2 at 22 (708 vs 642 g) and 49 d (2,948 vs 2,797 g), percentage leg problems was lower in Treatments 2 to 4 (9, 10 and 6%, respectively) than in Treatment 1 (20%), and percentage Grade A was greater in Treatment 4 than Treatment 2 (60 vs 46%) at 49 d. In Experiment 2, BW was greater in Treatment 1 (692 g) than Treatments 3 (617 g) and 4 (620 g) at 21 d, and the incidence of tibial dyschondroplasia was lower in Treatment 2 (3.1%) than Treatment 3 (15.3%) at 42 d. There were no differences for mortality among treatments in either experiment.

Nonlinear dynamics stability measurements of locomotion in healthy greyhounds.

OBJECTIVE: To characterize normal locomotion of dogs, using nonlinear dynamic stability measurements to analyze two-dimensional kinematic data. ANIMALS: 5 healthy, orthopedically sound Greyhounds. PROCEDURE: Data were studied by sequentially constructing phase plane portraits from the angular velocity and displacement data; creating first-return (Poincaré) maps from periodically sampled data; and evaluating the dynamic stability of the gait, using Floquet multipliers calculated from the assembled data. Retroreflective markers were placed on the left craniodorsal aspect of the iliac spine, greater trochanter, lateral epicondyle of the femur, lateral malleolus, and fifth metatarsophalangeal joint. Each dog was repeatedly led at a trot along a 10-m runway. Data were collected, using a video-based, two-dimensional motion measurement and analysis system. Dogs were considered a nonlinear system and were represented by the joint angular displacements and velocities. Phase plane portraits and first-return maps were constructed to analyze the smoothed data. The Floquet theory was then used to investigate the local stability of critical points of the discrete map. RESULTS: The femorotibial joint had the highest angular velocity, ranging from -2.5 to 4.9 radians/s. Tarsal joint velocity ranged from -2.7 to 3.2 radians/s, and the coxofemoral angle had the lowest range of -2.2 to 2.2 radians/s. The points on the first-return maps converged to the 45 degrees diagonal line and were clustered together. The largest Floquet multiplier averaged 0.452, which characterized the stability of this population and will be used to draw a comparison between this and future work. CONCLUSIONS: Nonlinear dynamics can be effectively used to analyze two-dimensional kinematic data from animal models to quantify the dynamic stability of animal locomotion through precise mathematical measurements. The method is general and can be applied to normal or abnormal gaits. CLINICAL RELEVANCE: Point mapping and quantitative measurement of joint movement have several advantages associated with the application to animal and human locomotion. The clinician can visually distinguish the normal gait pattern from abnormal patterns to assist in the diagnosis of musculoskeletal abnormalities (diseases).

Immunolocalization of stromelysin, tumor necrosis factor (TNF) alpha, and TNF receptors in atrophied canine articular cartilage treated with hyaluronic acid and transforming growth factor beta.

OBJECTIVE: To evaluate the ability of hyaluronic acid (HA), with and without transforming growth factor beta (1GF-beta), to stabilize the catabolic processes associated with atrophy of articular cartilage. ANIMALS: 20 adult, skeletally normal, hound-type dogs. PROCEDURE: Dogs (20 to 30 kg) were randomly assigned to 1 of 5 groups. One group served as untreated controls. Bivalve casts were placed on the left hind limbs of the remaining 16 dogs to limit weightbearing and motion of the limb for 92 days. One group served as the cast control. Beginning on day 56, 3 groups received aseptic intra-articular injections in the left stifles of either 5 mg of HA or 5 mg of HA containing either 20 or 50 micrograms of TGF-beta. Intraarticular injections were repeated at 4-day intervals until the end of the study. Or day 92, stifles were harvested at necroscropy. Medial femoral condyle were histologically processed, and the articular cartilage was stained for the presence of proteoglycans, stromelysin, tumor necrosis facto (TNF) alpha, and TNF receptors (p55 and p75). RESULTS: Decreased metachromasia was evident in the cartilage matrix of all cast groups, with the smallest decrease in the HA-treated group. Stromelysin was immunolocalized in articular cartilage of the cast (left) limbs of cast control and both HA/TGF-beta-treated groups. TNF-alpha was localized in articular cartilage of all cast (left) and right limbs, except those of the HA-treated group. Receptors for TNF were observed in both limbs of untreated control and cast control groups and cast limbs of HA/TGF-3-treated groups. The receptors were not localized in the right limbs of the HA with or without TGF-beta-treated groups. TGF-beta did not decrease stromelysin or TNF-alpha or receptors at the doses used. CONCLUSIONS: HA may mediate a chondrostabilizing influence on articular cartilage by down-regulating TNF-alpha importantly. HA appeared to exert its inhibitory influence on TNF-alpha, as well as stromelysin and TNF receptors, on a systemic basis. CLINICAL RELEVANCE: Results provide insight into the mode of action of HA as a therapeutic agent for arthritis and its stabilizing influence on cartilage metabolism.