Beneficial and harmful effects of physical activity on care-seeking for low back pain: the AUTBACK study.

PURPOSE: People who seek more care for low back pain (LBP) tend to experience poorer recovery (e.g. higher pain and disability levels). Understanding the factors associated with care-seeking for LBP might improve patient outcomes and potentially alleviate the burden of LBP on global health systems. This study aimed to investigate the relationship between different intensities, volumes, and domains of physical activity and care-seeking behaviours, in people with a history of LBP. METHODS: Longitudinal data from adult twins were drawn from the AUstralian Twin BACK study. The primary outcome was the total self-reported frequency (counts) of overall utilisation of care for LBP, over 1 year. Secondary outcomes were the utilisation of health services, and the utilisation of self-management strategies, for LBP (assessed as total frequency over 1 year). Explanatory variables were device-based measures of sedentary behaviour and moderate-to-vigorous intensity physical activity, and self-reported physical workload, and work, transport, household, and leisure domain physical activity, at baseline. RESULTS: Data from 340 individuals were included. Median age was 56.4 years (IQR 44.9-62.3 years) and 73% of participants were female. Medium-to-high baseline volumes of sedentary behaviour were significantly associated with greater counts of overall care utilisation (IRR 1.60, 95%CI 1.04-2.44) and utilisation of self-management strategies (IRR 1.60, 95%CI 1.02-2.50) for LBP, over 1 year. Medium-to-high baseline volumes of household domain physical activity were significantly associated with greater counts of utilising self-management strategies for LBP over 1 year (IRR 1.62, 95%CI 1.04-2.53). No explanatory variables were associated with the utilisation of health services for LBP. CONCLUSION: People who engage in higher baseline volumes of sedentary behaviour or physical activity in the household setting (e.g. housework, gardening, yard work, general household maintenance) utilise 1.6 times more care for LBP over 1 year. Findings suggest that higher volumes of these behaviours may be harmful for LBP. No intensities, volumes, or domains of physical activity demonstrated clear benefits for LBP. Where feasible, patients and clinicians should collaborate to screen and develop strategies to reduce engagement in sedentary behaviour or physical activity in the household setting. Contextual factors (e.g. patient symptom severity, sociocultural roles, occupational demands) should be considered when devising appropriate behaviour change strategies.

The effects of competition on the strength and softness of selection.

Deleterious alleles are constantly introduced into populations due to mutation. In subdivided populations, the impact of these mutations depends on the strength of selection as well as the softness of selection, that is, the extent to which fitness is governed by local rather than global competition. It is widely appreciated that the intensity and type of competition will affect selection on deleterious mutations but most empirical work has focused solely on the effects of competition on selection strength. However, competition has rarely been studied in the context of selection 'softness' even though competition is at the conceptual root of soft selection. All other things being equal, theory predicts that inter- and intraspecific competitions have opposing effects on the softness of selection. Using Drosophila melanogaster, we estimated the strength and softness of selection in a 'baseline' competitive environment as well as two additional competitive environments characterized by either additional intra- or interspecific competitors. We found that competitive environment had little effect on the average strength of selection. While the softness of selection was affected by the type of competition, the direction of change varied across tests of different genes, contrary to expectation. Although the 'hard/soft' selection paradigm implicitly assumes that all individuals are equally sensitive to the local competitive environment, we found this not to be the case. Wild-type individuals were more sensitive to changes in the genetic quality of their local competitors than mutant individuals.

Sensitivity, specificity and clinical relevance of different cross-matching assays in deceased-donor renal transplantation.

To assess the significance of antibodies detected by complement-dependent cytotoxicity (CDC), solid phase (SPA) and flow cytometry (FC) assays we compared their predictive value in 354 consecutive cases of deceased-donor kidney transplantation. Pre-transplantation screening of anti-HLA class I and class II antibodies was performed by CDC and SPA. The direct crossmatch between recipients' sera and donors' T and B cells was performed by CDC followed by FC and SPA ("virtual cross-match"). The past history of antibodies displayed by the recipient was not considered a contraindication for transplantation even when it showed DSA. A side-by-side comparison of the correlation between graft loss, history of DSA and cross-match results indicated that sensitivity was 5%, 16% and 17% while specificity was 99%, 93% and 86% in CDC, SPA, FC crossmatches respectively. There was no significant difference between the 3 year survival of primary and secondary kidney allografts. We conclude that screening and cross-matching the sera by CDC provides reliable results and optimizes the patient's chances to receive a transplant. SPA and FC, however, are of great importance for identifying patients which require close monitoring by biopsy and serology for early diagnosis and treatment of acute antibody mediated rejection (AAMR).

Anti-CD25 treatment and FOXP3-positive regulatory T cells in heart transplantation.

The interleukin-2 receptor alpha chain (IL-2Ra, CD25) plays a major part in shaping the dynamics of T cell populations following immune activation, due to its role in T cell proliferation and survival. Strategies to blunt the effector responses in transplantation have been developed by devising pharmaceutical agents to block the IL-2 pathways. However, such strategies could adversely affect the CD25(+)FOXP3(+)T regulatory (T reg) populations which also rely on intereukin-2 signaling for survival. The present study shows that a cohort of heart allograft recipients treated with Daclizumab (a humanized anti-CD25 antibody) display FOXP3 expression patterns consistent with functional T regulatory cell populations. High levels of FOXP3 were observed to correlate with lower incidence of and recovery from acute rejection, as well as lower levels of anti-donor HLA antibody production. Therefore, T reg populations appear fully functional in patients treated with Daclizumab, even when 5 doses were administered. By comparison, patients treated with fewer doses or no Daclizumab had a higher incidence of acute rejection, antibody production and graft failure. Therefore, our data indicates that Daclizumab treatment does not interfere with the generation of regulatory T cells and has a beneficial effect on heart allograft survival.

The spectrum of myelodysplastic syndromes post-solid organ transplantation: a single institutional experience.

An increased incidence of acute myeloid leukemia (AML) has recently been documented in patients post-solid organ transplantation but the incidence and types of myelodysplastic syndromes (MDS) occurring in this patient population are not known. We identified 5 patients (3M, 2F, age 48-64 years) who developed MDS ranging from 1.8 to 25 years (median 4.2 years) post-solid organ transplantation, only 2 patients had received azathioprine. The cumulative incidence of MDS in heart and lung transplant recipients at 15 years was 0.5% and 1.8%, respectively, which is markedly higher compared to the general population. Low-risk types of MDS predominated, 3 of 5 patients are alive (median 3.9 years) since diagnosis. Deletions of chromosome 20q, which have not been previously reported in post-transplant MDS/AML, were identified in 3 cases. Our findings expand the morphologic and cytogenetic spectrum of MDS occurring post-solid organ transplantation and suggest that mechanisms beside azathioprine toxicity might be important in disease pathogenesis.

Analyzing holistic parsers: implications for robust parsing and systematicity.

Holistic parsers offer a viable alternative to traditional algorithmic parsers. They have good generalization performance and are robust inherently. In a holistic parser, parsing is achieved by mapping the connectionist representation of the input sentence to the connectionist representation of the target parse tree directly. Little prior knowledge of the underlying parsing mechanism thus needs to be assumed. However, it also makes holistic parsing difficult to understand. In this article, an analysis is presented for studying the operations of the confluent preorder parser (CPP). In the analysis, the CPP is viewed as a dynamical system, and holistic parsing is perceived as a sequence of state transitions through its state-space. The seemingly one-shot parsing mechanism can thus be elucidated as a step-by-step inference process, with the intermediate parsing decisions being reflected by the states visited during parsing. The study serves two purposes. First, it improves our understanding of how grammatical errors are corrected by the CPP. The occurrence of an error in a sentence will cause the CPP to deviate from the normal track that is followed when the original sentence is parsed. But as the remaining terminals are read, the two trajectories will gradually converge until finally the correct parse tree is produced. Second, it reveals that having systematic parse tree representations alone cannot guarantee good generalization performance in holistic parsing. More important, they need to be distributed in certain useful locations of the representational space. Sentences with similar trailing terminals should have their corresponding parse tree representations mapped to nearby locations in the representational space. The study provides concrete evidence that encoding the linearized parse trees as obtained via preorder traversal can satisfy such a requirement.

How to design a connectionist holistic parser.

Connectionist holistic parsing offers a viable and attractive alternative to traditional algorithmic parsers. With exposure to a limited subset of grammatical sentences and their corresponding parse trees only, a holistic parser is capable of learning inductively the grammatical regularity underlying the training examples that affects the parsing process. In the past, various connectionist parsers have been proposed. Each approach had its own unique characteristics, and yet some techniques were shared in common. In this article, various dimensions underlying the design of a holistic parser are explored, including the methods to encode sentences and parse trees, whether a sentence and its corresponding parse tree share the same representation, the use of confluent inference, and the inclusion of phrases in the training set. Different combinations of these design factors give rise to different holistic parsers. In succeeding discussions, we scrutinize these design techniques and compare the performances of a few parsers on language parsing, including the confluent preorder parser, the backpropagation parsing network, the XERIC parser of Berg (1992), the modular connectionist parser of Sharkey and Sharkey (1992), Reilly's (1992) model, and their derivatives. Experiments are performed to evaluate their generalization capability and robustness. The results reveal a number of issues essential for building an effective holistic parser.

A new method for casting discrepancy: some results for a phosphate-bonded investment.

OBJECTIVES: An accurate and realistic casting discrepancy method applicable to base metal alloys has hitherto been lacking. The purpose of this study was to develop a method for determining casting discrepancy free of interference from oxide, slag and surface defects, working under realistic conditions. In addition, a variable was sought that could be used for calibrating the casting process to allow for local errors. METHODS: A crown pattern was designed to incorporate circular V-grooves on the margin and the inside surface of the occlusal part for determination of the 'groove root diameter' (GRD) with a measuring microscope. Castings using a phosphate-bonded investment were made to test the effects of 'hygroscopic' expansion, burn-out temperature, powder/liquid ratio and groove location. RESULTS: The tested investment variables showed the expected effects, but the distortion between marginal and pulpal regions was clearly shown, as were interactions between some variables. 'Special liquid' proportion appears to be a good candidate variable for process calibration. CONCLUSIONS: The GRD method was shown to be sensitive and reproducible. It is also applicable to many other casting systems, and in particular to monitoring overall process discrepancy, i.e. from tooth preparation to casting, which is suggested as being the key issue.

Immunologic monitoring in lung allograft recipients.

To identify patients with increased risk of chronic lung allograft rejection, we assessed the utility of an in vitro biopsy-derived lymphocyte growth assay and serum anti-HLA antibody screening as a complement to currently available methods of monitoring lung allograft recipients. Lymphocyte growth assay was performed on bronchoscopic fragments of tissue cultured in medium with rIL-2. Seventy-nine biopsies from 31 lung transplant recipients were tested by lymphocyte growth assay, and results were correlated with histopathology findings. Positive lymphocyte growth was found in 12/26 (46%) episodes of acute rejection, 5/44 biopsies without rejection (11%), and 0/9 episodes of bronchitis. Positive lymphocyte growth was seen in 7/16 (44%) grade A1 rejections and in 5/10 (50%) grade A2 rejections, as opposed to only 5/44 (11%) grade A0 (no rejection) biopsies (P < 0.01 for both A1 and A2 with respect to A0). Actuarial probability of remaining free from obliterative bronchiolitis (OB)* tended to be higher in patients who did not exhibit lymphocyte growth in biopsies. Sequential samples of sera obtained at the time of the biopsy were screened for lymphocytotoxic anti-HLA antibodies. Twenty-two of 44 recipients (50%) developed anti-HLA antibodies during the first postoperative year, exhibiting greater than 10% reactivity to an HLA reference panel of lymphocytes in four or more consecutive serum samples. Actuarial survival of lung allograft recipients with anti-HLA antibodies (n = 22) was lower than in those without anti-HLA antibodies (n = 22; P = 0.03). Of the 22 antibody producers, 7/12 died as a consequence of OB. Of the 22 non-antibody-producers, 1/2 deaths occurred as a consequence of OB. Anti-HLA antibodies were present in 9/11 instances of OB (82% sensitivity) and in 13/33 patients without OB (61% specificity; P = 0.03). These data indicate that lung transplant recipients with positive lymphocyte growth and anti-HLA antibodies are at an increased risk of chronic allograft rejection.

Fracture of the odontoid peg in ankylosing spondylitis: case report.

Fractures in patients with ankylosing spondylitis tend to affect the lower cervical spine. We describe a 50-year-old man who sustained fractures of the odontoid peg and body of the second cervical vertebra after a hyperextension injury. In absence of atlanto-occipital fusion, deformity from previous lower cervical spine injury may have contributed to susceptibility for this very rare combination of fractures. The patient was treated surgically with a good result.

New prognostic factors to predict the final outcome of brace treatment in adolescent idiopathic scoliosis.

STUDY DESIGN: Eighty-five patients with adolescent idiopathic scoliosis treated with Milwaukee or thoracolumbosacral orthoses at The Duchess of Kent Children's Hospital were studied longitudinally at 4-6-month intervals until maturity for spinal curvature and vertebral rotation, or until termination of brace treatment for persons who experienced brace failure who went on to have surgery. OBJECTIVES: To identify radiologic features so that it may be possible to predict outcome of brace treatment early on. SUMMARY OF BACKGROUND DATA: The structural curve with poor flexibility and large rotational prominence have been found to be associated with poor prognosis for brace treatment. However, early response to bracing for spinal deformity and its relationship to final outcome of brace treatment in a longitudinal study is not available in the literature. METHODS: Vertebral rotation and Cobb angles measured from anteroposterior radiographs of the spine obtained before bracing and 1-2 months after bracing were found valuable for prediction. Changes in post-brace Cobb angle and vertebral rotation were considered as an increase or reduction only when there was an increase or reduction of minimum 5 degrees or more from their prebrace measurements. RESULTS: Those patients who showed increase in vertebral rotation and/or in Cobb angle after brace application were shown to have progression of curves leading to brace failure in 93% of patients, and 79% of these required surgery. The patients with no change in both vertebral rotation and Cobb angle after bracing often experienced brace failure (69%). Two patients (15%) required surgery. The results show that reduction of both Cobb angle and vertebral rotation after application of a brace is a prognostic indicator for a good outcome (97%), and no patients required surgery. Most of the patients with lumbar scoliosis (91%) showed such reductions. CONCLUSION: The findings show a strong association between changes in vertebral rotation and the Cobb angle after application of a brace and the final outcome. Reduction in both is indicative of a good outcome, whereas increase in one or both indicates brace failure.

Bone mineral density in ankylosing spondylitis. DEXA comparison of control subjects with mild and advanced cases.

We have used dual-energy X-ray absorptiometry to measure bone mineral density (BMD) in patients with ankylosing spondylitis comparing 41 healthy control subjects and 33 patients with either mild or advanced ankylosing spondylitis. A Norland XR-28 bone densitometer was used to measure the BMD of the lumbar spine and that of the head, trunk, arms, femoral neck, Ward's triangle, legs, pelvis, and total body. Mild ankylosing spondylitis was defined as that showing no or incipient syndesmophytes between L1 and L5 vertebrae: we studied 16 men of mean age 37 years and six women of mean age 37 years. Advanced ankylosing spondylitis, in 11 men of mean age 42 years, showed a bamboo spine with bridging syndesmophytes across all disc spaces between L1 and L5. The mean BMD of the lumbar spine was significantly different in the patients and control subjects of the same sex (0.01 < p < 0.05, analysis of variance), being significantly reduced compared with control subjects in mild disease (0.001 < p < 0.01, t-test) and significantly increased in advanced disease over control subjects (0.01 < p < 0.05; t-test) and over patients with mild disease (0.001 < p < 0.01; t-test). The relevance of these findings to the aetiology and pathogenesis of spinal deformities and other complications in ankylosing spondylitis is discussed.

Pulmonary functions in congenital scoliosis.

STUDY DESIGN: Thirty-six patients with congenital scoliosis underwent full clinical and radiologic evaluation of their deformity and their full pulmonary functions. OBJECTIVES: This study observed pulmonary functions in congenital scoliosis in detail, evaluated pulmonary functions in nonsurgically treated patients, and established whether, in surgically treated patients, there are any differences between those with multiple thoracic anomalies and those with lumbar or one of two thoracic anomalies. SUMMARY OF BACKGROUND DATA: Eighty-six of our patients in both groups (surgically and nonsurgically treated) showed abnormal increases in residual volumes, indicating a restrictive pattern of lung function. The results of their pulmonary functions were analyzed using predicted values to eliminate age affect. METHODS: Pulmonary functions were assessed using the Gould 5000IV Computerized Pulmonary Function System. RESULTS: Overall, mean total lung capacity was 89% of predicted value, and mean vital capacity and forced vital capacity were 74% of predicted value. The mean residual volume was significantly increased, being 154% of predicted value. Nonsurgically treated patients showed normal total lung capacity (mean 99.8% of predicted value); this mean value was 82% of predicted value in surgically treated patients. CONCLUSION: Vital capacity was found to be significantly reduced in surgically treated patients (68% of predicted value), especially in those patients who had multiple thoracic anomalies. We believe that children with congenital scoliosis due to multiple anomalies should be operated on at an early age before deformity is too severe.

Nine-year mean follow-up of one-stage anteroposterior excision of hemivertebrae in the lumbosacral spine.

Six patients with lumbosacral hemivertebrae were treated by one-stage anterior and posterior excision of the hemivertebrae. Long-term follow-up is reported. Overall, correction of the lumbosacral curve was 46%, including one case of pseudarthrosis and subsequent loss of correction. More importantly, truncal imbalance was restored unless other congenital thoracic anomalies were present. New methods of calculating rib cage shift on the pelvis as well as vertebral column displacement from the sagittal plane are presented.

New methods of measuring vertebral rotation from computed tomographic scans. An intraobserver and interobserver study on girls with scoliosis.

The purpose of this study was to search for constant and reliable reference points on the computed tomographic scans of scoliotic spines to measure vertebral rotation. Several methods using different sets of reference points on computed tomographic scans were tested for reliability. Two methods that gave minimum variation between the readings are presented here with interobserver and intraobserver reliability on 17 girls with adolescent idiopathic scoliosis. The selection of reference points for the two methods were as follows: In method 1, the vertebral rotation was an angle formed by two lines; one, a line joining the junction of the inner surfaces of two laminae and the midpoint of the posterior surface of the vertebral body and second, the vertical plane of the computed tomographic machine. In method 2, three datum points were marked; one at the junction of the inner surfaces of the laminae, and the other, one each at the junction of the inner surfaces of the lamina and the pedicle. A line bisecting this angle is drawn by the computer and the vertebral rotation was an angle between this line and the vertical plane. The 95% confidence intervals of these two methods for intraobserver variation were between 1.2 to 4.4 degrees. There was no significant difference between the readings obtained by each observer except on three occasions for observer 1. When these methods were tested for interobserver reliability, method 1 showed significant statistical differences between the readings obtained by the two observers. However, the readings obtained using method 2 were not significantly different between the two observers (95% confidence intervals = 3.2 to 5.8 degrees).(ABSTRACT TRUNCATED AT 250 WORDS)

Changes in residual volume relative to vital capacity and total lung capacity after arthrodesis of the spine in patients who have adolescent idiopathic scoliosis.

We evaluated pulmonary functions before correction and again after a mean follow-up of three years in thirty-five patients who had adolescent idiopathic scoliosis. The mean age (and standard deviation) at the time of correction was 13.7 +/- 1.8 years, and at the time of follow-up it was 17.1 +/- 2.5 years. The findings in the patients were compared with those in matched normal control subjects. With the exception of forced vital capacity, all of the determinations of absolute pulmonary volume increased postoperatively, but the increases were not all proportional. When the preoperative and follow-up determinations were expressed as percentages of the predicted pulmonary volumes (on the basis of age) to eliminate any effects of the difference in age, there was no change in total lung capacity, but vital capacity and forced vital capacity were significantly reduced. In addition, there was a significant increase in residual volume. Of the mean increase in total lung capacity after correction of the scoliosis, 82 per cent was due to an increase in residual volume and 18 per cent, to an increase in vital capacity. However, in control subjects age-matched at the time of follow-up, the increase in vital capacity contributed 69 per cent of the mean increase in total lung capacity, a very marked difference from the findings in the patients who had scoliosis. In addition, two pulmonary-volume ratios--residual volume to vital capacity and residual volume to total lung capacity--increased in a highly significant fashion (Mann-Whitney test, p < 0.001) after arthrodesis of the spine.(ABSTRACT TRUNCATED AT 250 WORDS)

A comparative study of computed tomographic and plain radiographic methods to measure vertebral rotation in adolescent idiopathic scoliosis.

A comparative analysis of two methods of measuring vertebral rotation in adolescent idiopathic scoliosis is reported in this article. Nash and Moe's pedicle shift method (using plain anteroposterior radiographs) is compared with a new method using computed tomographic scans. The computed tomographic scans of the whole length of the major curve and the scout films obtained from seventeen girls aged 12.5-14 years were measured for rotation of each vertebra of the curve (total number of vertebrae measured by two methods = 173). This study has three interesting new findings: 1) Those vertebrae with Nash & Moe grade 0 had up to 11 degrees of vertebral rotation when measured using the computed tomographic method. Therefore, Nash & Moe's grade '0' is not a neutrally rotated vertebra; 2) For Nash & Moe grade 1 and 2, the computed tomographic method revealed statistically significantly greater rotation for lumbar vertebrae than thoracic vertebrae. There was a similar pattern for Nash & Moe grade 0 but these differences were not statistically significant; and 3) Simple formulae are reported to convert Nash & Moe's grades into angle of vertebral rotation as obtained by CT method separately for thoracic and lumbar vertebrae.

The shoulder girdle in ankylosing spondylitis.

We report the clinical findings in the shoulders of fifty-two patients who had ankylosing spondylitis. The three major patterns that were found included limitation of scapulothoracic motion (forty-one patients), acute inflammatory arthropathy of the sternoclavicular or acromioclavicular joint (six patients), and severe restriction of glenohumeral motion (five patients). Although radiographic abnormalities were common, they correlated with the clinical findings in only minor respects.