Effects of brood size manipulation and common origin on phenotype and telomere length in nestling collared flycatchers.

BACKGROUND: Evidence is accumulating that telomere length is a good predictor of life expectancy, especially early in life, thus calling for determining the factors that affect telomere length at this stage. Here, we investigated the relative influence of early growth conditions and origin (genetics and early maternal effects) on telomere length of collared flycatchers (Ficedula albicollis) at fledging. We experimentally transferred hatchlings among brood triplets to create reduced, control (i.e. unchanged final nestling number) and enlarged broods. RESULTS: Although our treatment significantly affected body mass at fledging, we found no evidence that increased sibling competition affected nestling tarsus length and telomere length. However, mixed models showed that brood triplets explained a significant part of the variance in body mass (18%) and telomere length (19%), but not tarsus length (13%), emphasizing that unmanipulated early environmental factors influenced telomere length. These models also revealed low, but significant, heritability of telomere length (h(2) = 0.09). For comparison, the heritability of nestling body mass and tarsus length was 0.36 and 0.39, respectively, which was in the range of previously published estimates for those two traits in this species. CONCLUSION: Those findings in a wild bird population demonstrate that telomere length at the end of the growth period is weakly, but significantly, determined by genetic and/or maternal factors taking place before hatching. However, we found no evidence that the brood size manipulation experiment, and by extension the early growth conditions, influenced nestling telomere length. The weak heritability of telomere length suggests a close association with fitness in natural populations.

Lumbar spine texture enhances 10-year fracture probability assessment.

We found that lumbar spine texture analysis using trabecular bone score (TBS) is a risk factor for MOF and a risk factor for death in a retrospective cohort study from a large clinical registry for the province of Manitoba, Canada. INTRODUCTION: FRAX® estimates the 10-year probability of major osteoporotic fracture (MOF) using clinical risk factors and femoral neck bone mineral density (BMD). Trabecular bone score (TBS), derived from texture in the spine dual X-ray absorptiometry (DXA) image, is related to bone microarchitecture and fracture risk independently of BMD. Our objective was to determine whether TBS provides information on MOF probability beyond that provided by the FRAX variables. METHODS: We included 33,352 women aged 40-100 years (mean 63 years) with baseline DXA measurements of lumbar spine TBS and femoral neck BMD. The association between TBS, the FRAX variables, and the risk of MOF or death was examined using an extension of the Poisson regression model. RESULTS: During the mean of 4.7 years, 1,754 women died and 1,872 sustained one or more MOF. For each standard deviation reduction in TBS, there was a 36 % increase in MOF risk (HR 1.36, 95 % CI 1.30-1.42, p < 0.001) and a 32 % increase in death (HR 1.32, 95 % CI 1.26-1.39, p < 0.001). When adjusted for significant clinical risk factors and femoral neck BMD, lumbar spine TBS was still a significant predictor of MOF (HR 1.18, 95 % CI 1.12-1.23) and death (HR 1.20, 95 % CI 1.14-1.26). Models for estimating MOF probability, accounting for competing mortality, showed that low TBS (10th percentile) increased risk by 1.5-1.6-fold compared with high TBS (90th percentile) across a broad range of ages and femoral neck T-scores. CONCLUSIONS: Lumbar spine TBS is able to predict incident MOF independent of FRAX clinical risk factors and femoral neck BMD even after accounting for the increased death hazard.

Effects of brood manipulation costs on optimal sex allocation in social hymenoptera.

In eusocial Hymenoptera, queens and workers are in conflict over optimal sex allocation. Sex ratio theory, while generating predictions on the extent of this conflict under a wide range of conditions, has largely neglected the fact that worker control of investment almost certainly requires the manipulation of brood sex ratio. This manipulation is likely to incur costs, for example, if workers eliminate male larvae or rear more females as sexuals rather than workers. In this article, we present a model of sex ratio evolution under worker control that incorporates costs of brood manipulation. We assume cost to be a continuous, increasing function of the magnitude of sex ratio manipulation. We demonstrate that costs counterselect sex ratio biasing, which leads to less female-biased population sex ratios than expected on the basis of relatedness asymmetry. Furthermore, differently shaped cost functions lead to different equilibria of manipulation at the colony level. While linear and accelerating cost functions generate monomorphic equilibria, decelerating costs lead to a process of evolutionary branching and hence split sex ratios.

Análisis de la Morfología del Raquis Torácico y Lumbar en Mujeres Trabajadoras de una Cooperativa Hortofrutícola

The aim of this study was to analyze the sagittal spinal morphology of thoracic and lumbar spine in standing and sitting in women workers from a cooperative in the production, handling and marketing business of vegetable and fruit products. A total of 50 women (mean age: 43.62±8.43 years old) were evaluated. The Spinal Mouse system was used to mesasure the sagittal thoracic and lumbar curvatures in standing and relaxed sitting. The values for thoracic and lumbar curvatures were 32.74±8.76 and -21.66±19.12 in standing and 36.32±10.55 and -1.08±18.14 in sitting. A high frequency (86.0% and 68.3%) of normal thoracic kyphosis and lumbar lordosis were found in standing posture. While sitting the 74.0% and 20.0% presented thoracic hyperkyphosis and lumbar kyphosis. In conclusion, a high percentaje of women workers presented normality values in standing posture, although a high percentage of women were found with thoracic hyperkyphosis and lumbar flexed while sitting relaxed. It is recommended that these women carry out a program to improve their actitudinal postures in their work place.

Short- and long-term effects of litter size manipulation in a small wild-derived rodent.

Iteroparous organisms maximize their overall fitness by optimizing their reproductive effort over multiple reproductive events. Hence, changes in reproductive effort are expected to have both short- and long-term consequences on parents and their offspring. In laboratory rodents, manipulation of reproductive efforts during lactation has however revealed few short-term reproductive adjustments, suggesting that female laboratory rodents express maximal rather than optimal levels of reproductive investment as observed in semelparous organisms. Using a litter size manipulation (LSM) experiment in a small wild-derived rodent (the common vole; Microtus arvalis), we show that females altered their reproductive efforts in response to LSM, with females having higher metabolic rates and showing alternative body mass dynamics when rearing an enlarged rather than reduced litter. Those differences in female reproductive effort were nonetheless insufficient to fully match their pups' energy demand, pups being lighter at weaning in enlarged litters. Interestingly, female reproductive effort changes had long-term consequences, with females that had previously reared an enlarged litter being lighter at the birth of their subsequent litter and producing lower quality pups. We discuss the significance of using wild-derived animals in studies of reproductive effort optimization.

Influence of anatomical variations on lumbar foraminal stenosis pathogenesis.

INTRODUCTION: Symptomatic foraminal stenosis has been observed in patients with degenerative disc disease, scoliosis, asymmetrical disc degeneration and spondylolisthesis. Nevertheless not all patients with the above pathologies will develop symptomatic foraminal stenosis. We hypothesised that symptomatic patients have anatomical predisposition to foraminal stenosis, namely a larger pedicle height (PH) to vertebral body height (VH) ratio, leaving less room below the pedicle for the exiting nerve root compared to asymptomatic patients. PATIENT SAMPLE: 66 Patients were divided in two groups. The surgical group consisted of 37 patients (average age of 61 years) who presented with severe radicular symptoms resisting to conservative measures and requiring decompression and transforaminal lumbar interbody fusion (TLIF). The control group consisted of 29 patients (average age of 51 years) presenting with low back pain (LBP) but with no radicular symptoms and who were treated conservatively. METHODS: We measured VH at the level of the posterior wall as well as PH on parasagittal images (CT or MRI) on all lumbar levels (L1 to L5). Statistical analysis was performed using Student's t test. RESULTS: No difference in PH was found between the two groups for L1 to L4 levels. By contrast, there was a highly statistically significant difference in VH between the two groups from L1 to L4 level. In the surgical group, the VH was smaller (p < 0.001). CONCLUSIONS: Symptomatic patients with foraminal stenosis have smaller VH leading to lesser space beneath the pedicle and putting the exiting nerve root at risk in cases of spondylolisthesis or disc degeneration.

Surgical treatment of lumbar spinal stenosis. Five-year follow-up.

We carried out a retrospective review of 155 patients with lumbar spinal stenosis who had been treated surgically and followed up regularly: 77 were evaluated at a mean of 6.5 years (5 to 8) after surgery by two independent observers. The outcome was assessed using the scoring system of Roland and Morris, and the rating system of Prolo, Oklund and Butcher. Instability was determined according to the criteria described by White and Panjabi. A significant decrease in low back pain and disability was seen. An excellent or good outcome was noted in 79% of patients; 9% showed secondary radiological instability. Surgical decompression is a safe and efficient procedure. In the absence of preoperative radiological evidence of instability, fusion is not required.

Influence of preoperative leg pain and radiculopathy on outcomes in mono-segmental lumbar total disc replacement: results from a nationwide registry.

PURPOSE: Currently, many pre-conditions are regarded as relative or absolute contraindications for lumbar total disc replacement (TDR). Radiculopathy is one among them. In Switzerland it is left to the surgeon's discretion when to operate if he adheres to a list of pre-defined indications. Contraindications, however, are less clearly specified. We hypothesized that, the extent of pre-operative radiculopathy results in different benefits for patients treated with mono-segmental lumbar TDR. We used patient perceived leg pain and its correlation with physician recorded radiculopathy for creating the patient groups to be compared. METHODS: The present study is based on the dataset of SWISSspine, a government mandated health technology assessment registry. Between March 2005 and April 2009, 577 patients underwent either mono- or bi-segmental lumbar TDR, which was documented in a prospective observational multicenter mode. A total of 416 cases with a mono-segmental procedure were included in the study. The data collection consisted of pre-operative and follow-up data (physician based) and clinical outcomes (NASS form, EQ-5D). A receiver operating characteristic (ROC) analysis was conducted with patients' self-indicated leg pain and the surgeon-based diagnosis "radiculopathy", as marked on the case report forms. As a result, patients were divided into two groups according to the severity of leg pain. The two groups were compared with regard to the pre-operative patient characteristics and pre- and post-operative pain on Visual Analogue Scale (VAS) and quality of life using general linear modeling. RESULTS: The optimal ROC model revealed a leg pain threshold of 40 ≤ VAS > 40 for the absence or the presence of "radiculopathy". Demographics in the resulting two groups were well comparable. Applying this threshold, the mean pre-operative leg pain level was 16.5 points in group 1 and 68.1 points in group 2 (p < 0.001). Back pain levels differed less with 63.6 points in group 1 and 72.6 in group 2 (p < 0.001). Pre-operative quality of life showed considerable differences with an 0.44 EQ-5D score in group 1 and 0.29 in group 2 (p < 0.001, possible score range -0.6 to 1). At a mean follow-up time of 8 months, group 1 showed a mean leg pain improvement of 3.6 points and group 2 of 41.1 points (p < 0.001). Back pain relief was 35.6 and 39.1 points, respectively (p = 0.27). EQ-5D score improvement was 0.27 in group 1 and 0.41 in group 2 (p = 0.11). CONCLUSIONS: Patients labeled as having radiculopathy (group 2) do mostly have pre-operative leg pain levels ≥ 40. Applying this threshold, the patients with pre-operative leg pain do also have more severe back pain and a considerably lower quality of life. Their net benefit from the lumbar TDR is higher and they do have similar post-operative back and leg pain levels as well as the quality of life as patients without pre-operative leg pain. Although randomized controlled trials are required to confirm these findings, they put leg pain and radiculopathy into perspective as absolute contraindications for TDR.

Market rewards to patterns on increasing earnings: do cash flow patterns, accruals manipulation and real activities manipulation matter?

This study explores whether firms have differential price-earnings multiples associated with their means of achieving a sequential pattern of increasing positive earnings. Our main findings show that market participants assign higher price-earnings multiples to firms when their pattern of increasing earnings is supported by the same pattern of increasing cash flows. Market participants assign lower price-earnings multiples to firms suspect of having engaged in accrual-based earnings management, sales manipulation, and overproduction to achieve the earnings pattern. We find, however, that market participants do not penalize firms suspect of having achieved the earnings pattern through the opportunistic reduction of discretionary expenses.

Introducing a new MRI classification of lumbar spinal stenosis based on cross-sectional morphology of the dural sac : 37

Introduction: Measures of the degree of lumbar spinal stenosis (LSS) such as antero-posterior diameter of the canal, and dural sac cross sectional area vary, and do not correlate with symptoms or results of surgery. We created a grading system, comprised of seven categories, based on the morphology of the dural sac and its contents as seen on T2 axial images. The categories take into account the ratio of rootlet/ CSF content. Grade A indicates no significant compression, grade D is equivalent to a total myelograhic block. We compared this classification with commonly used criteria of severity of stenosis. Methods: Fifty T2 axial MRI images taken at disc level from 27 symptomatic LSS patients undergoing decompressive surgery were classified twice by two radiologists and three spinal surgeons working at different institutions and countries. Dural sac cross-sectional surface area and AP diameter of the canal were measured both at disc and pedicle level from DICOM images using OsiriX software. Intraand inter-observer reliability were assessed using Cohen's, Fleiss' kappa statistics, and t test. Results: For the morphological grading the average intra-and inter observer kappas were 0.76 and 0.69+, respectively, for physicians working in the study originating country. Combining all observers the kappa values were 0.57 ± 0.19. and 0.44 ± 0.19, respectively. AP diameter and dural sac cross-sectional area measurements showed no statistically significant differences between observers. No correlation between morphological grading and AP diameter or dural sac crosssectional areawas observed in 13 (26%) and 8 cases (16%), respectively. Discussion: The proposed morphological grading relies on the identification of the dural sac and CSF better seen on full MRI series. This was not available to the external observers, which might explain the lower overall kappa values. Since no specific measurement tools are needed the grading suits everyday clinical practice and favours communication of degree of stenosis between practising physicians. The absence of a strict correlation with the dural sac surface suggests that measuring the surface alone might be insufficient in defining LSS as it is essentially a mismatch between the spinal canal and its contents. This grading is now adopted in our unit and further studies concentrating on relation between morphology, clinical symptoms and surgical results are underway.

Decision-making in lumbar spinal stenosis: A survey on the influence of the morphology of the dural sac.

Surgical decision-making in lumbar spinal stenosis involves assessment of clinical parameters and the severity of the radiological stenosis. We suspected that surgeons based surgical decisions more on dural sac cross-sectional area (DSCA) than on the morphology of the dural sac. We carried out a survey among members of three European spine societies. The axial T2-weighted MR images from ten patients with varying degrees of DSCA and morphological grades according to the recently described morphological classification of lumbar spinal stenosis, with DSCA values disclosed in half the assessed images, were used for evaluation. We provided a clinical scenario to accompany the images, which were shown to 142 responding physicians, mainly orthopaedic surgeons but also some neurosurgeons and others directly involved in treating patients with spinal disorders. As the primary outcome we used the number of respondents who would proceed to surgery for a given DSCA or morphological grade. Substantial agreement among the respondents was observed, with severe or extreme stenosis as defined by the morphological grade leading to surgery. This decision was not dependent on the number of years in practice, medical density or specialty. Disclosing the DSCA did not alter operative decision-making. In all, 40 respondents (29%) had prior knowledge of the morphological grading system, but their responses showed no difference from those who had not. This study suggests that the participants were less influenced by DSCA than by the morphological appearance of the dural sac. Classifying lumbar spinal stenosis according to morphology rather than surface measurements appears to be consistent with current clinical practice.

Development of appropriateness criteria for the surgical treatment of symptomatic lumbar degenerative spondylolisthesis (LDS).

PURPOSE: Spine surgery rates are increasing worldwide. Treatment failures are often attributed to poor patient selection and inappropriate treatment, but for many spinal disorders there is little consensus on the precise indications for surgery. With an aging population, more patients with lumbar degenerative spondylolisthesis (LDS) will present for surgery. The aim of this study was to develop criteria for the appropriateness of surgery in symptomatic LDS. METHODS: A systematic review was carried out to summarize the current level of evidence for the treatment of LDS. Clinical scenarios were generated comprising combinations of signs and symptoms in LDS and other relevant variables. Based on the systematic review and their own clinical experience, twelve multidisciplinary international experts rated each scenario on a 9-point scale (1 highly inappropriate, 9 highly appropriate) with respect to performing decompression only, fusion, and instrumented fusion. Surgery for each theoretical scenario was classified as appropriate, inappropriate, or uncertain based on the median ratings and disagreement in the ratings. RESULTS: 744 hypothetical scenarios were generated; overall, surgery (of some type) was rated appropriate in 27 %, uncertain in 41 % and inappropriate in 31 %. Frank panel disagreement was low (7 % scenarios). Face validity was shown by the logical relationship between each variable's subcategories and the appropriateness ratings, e.g., no/mild disability had a mean appropriateness rating of 2.3 ± 1.5, whereas the rating for moderate disability was 5.0 ± 1.6 and for severe disability, 6.6 ± 1.6. Similarly, the average rating for no/minimal neurological abnormality was 2.3 ± 1.5, increasing to 4.3 ± 2.4 for moderate and 5.9 ± 1.7 for severe abnormality. The three variables most likely (p < 0.0001) to be components of scenarios rated "appropriate" were: severe disability, no yellow flags, and severe neurological deficit. CONCLUSION: This is the first study to report criteria for determining candidacy for surgery in LDS developed by a multidisciplinary international panel using a validated method (RAM). The panel ratings followed logical clinical rationale, indicating good face validity. The work refines clinical classification and the phenotype of degenerative spondylolisthesis. The predictive validity of the criteria should be evaluated prospectively to examine whether patients treated "appropriately" have better clinical outcomes.