Sequential Magnetic Resonance Imaging Reveals Individual Level Deformities of Vertebrae and Discs in the Growing Scoliotic Spine

STUDY DESIGN

The aim of this study was to measure contributions of individual vertebra and disc wedging to coronal Cobb angle in the growing scoliotic spine using sequential magnetic resonance imaging (MRI). Clinically, the Cobb angle measures the overall curve in the coronal plane but does not measure individual vertebra and disc wedging. It was hypothesized that patients whose deformity progresses will have different patterns of coronal wedging in vertebrae and discs to those of patients whose deformities remain stable.

METHODS

A group of adolescent idiopathic scoliosis (AIS) patients each received two to four MRI scans (spaced 3-12 months apart). The coronal plane wedge angles of each vertebra and disc in the major curve were measured for each scan, and the proportions and patterns of wedging in vertebrae and discs were analyzed for subgroups of patients whose spinal deformity did and did not progress during the study period.

RESULTS

Sixteen patients were included in the study; the mean patient age was 12.9 years (standard deviation 1.7 years). All patients were classified as right-sided major thoracic Lenke Type 1 curves (9 type 1A, 4 type 1B, and 3 type 1C). Cobb angle progression of ≥5° between scans was seen in 56% of patients. Although there were measurable changes in the wedging of individual vertebrae and discs in all patients, there was no consistent pattern of deformity progression between patients who progressed and those who did not. The patterns of progression found in this study did not support the hypothesis of wedging commencing in the discs and then transferring to the vertebrae.

CONCLUSION

Sequential MRI data showed complex patterns of deformity progression. Changes to the wedging of individual vertebrae and discs may occur in patients who have no increase in Cobb angle; therefore, the Cobb method alone may be insufficient to capture the complex mechanisms of deformity progression.

Developmental mechanisms of macroevolutionary change in the tetrapod axis: A case study of Sauropterygia

Understanding how developmental processes change on macroevolutionary timescales to generate body plan disparity is fundamental to the study of vertebrate evolution. Adult morphology of the vertebral column directly reflects the mechanisms that generate vertebral counts (somitogenesis) and their regionalisation (homeotic effects) during embryonic development. Sauropterygians were a group of Mesozoic marine reptiles that exhibited an extremely high disparity of presacral vertebral/somite counts. Using phylogenetic comparative methods, we demonstrate that somitogenesis and homeotic effects evolved in a co-ordinated way among sauropterygians, contrasting with the wider pattern in tetrapods, in which somitogenetic and homeotic shifts are uncorrelated. Changes in sauropterygian body proportions were primarily enabled by homeotic shifts, with a lesser, but important, contribution from differences in postpatterning growth among somites. High body plan plasticity was present in Triassic sauropterygians and was maintained among their Jurassic and Cretaceous descendants. The extreme disparity in the body plan of plesiosaurian sauropterygians did not result from accelerated rates of evolutionary change in neck length, but instead reflect this ancestral versatility of sauropterygian axial development. Our results highlight variation in modes of axial development among tetrapods, and show that heterogeneous statistical models can uncover novel macroevolutionary patterns for animal body plans and the developmental mechanisms that control them.

Life-history traits of the long-nosed skate Dipturus oxyrinchus

This work investigates life-history traits of the long-nosed skate Dipturus oxyrinchus, which is a common by-catch in Sardinian waters. The reproductive variables were analysed from 979 specimens sampled during scientific and commercial hauls. Females (10·4-117·5 cm total length, L_T ) attained larger sizes than males (14·5-99·5 cm L_T ). To evaluate age and growth, a sub-sample of 130 individuals (76 females and 54 males) were used. The age was estimated by annuli counts of sectioned vertebral centra. Four models were used for the length-at-age data: the von Bertalanffy, the exponential, the Gompertz and the logistic functions. According to the Akaike's information criterion, the Gompertz model seemed to provide the best fitting curve (L_∞ mean ± s.e.: 127·55 ± 4·90 cm, k: 0·14 ± 0·09, IP: 3·97 ± 0·90 years). The oldest female and male were aged 17 (115·5 cm L_T ) and 15 years (96·0 cm L_T ), respectively. Lengths at maturity were 103·5 cm for females and 91·0 cm for males, corresponding to 90% of the maximum observed length in both sexes. The monthly distribution of maturity stages highlighted an extended reproductive cycle, with spawning females and active males being present almost throughout the year, as confirmed by the gonado-somatic index. Ovarian fecundity reached a maximum of 26 yolked follicles with a mean ± s.e. size of 19·7 ± 6·5 mm.

IGF1 neuronal response in the absence of MECP2 is dependent on TRalpha 3

Rett syndrome (RTT) is an X-linked neurodevelopmental disorder in which the MECP2 (methyl CpG-binding protein 2) gene is mutated. Recent studies showed that RTT-derived neurons have many cellular deficits when compared to control, such as: less synapses, lower dendritic arborization and reduced spine density. Interestingly, treatment of RTT-derived neurons with Insulin-like Growth Factor 1 (IGF1) could rescue some of these cellular phenotypes. Given the critical role of IGF1 during neurodevelopment, the present study used human induced pluripotent stem cells (iPSCs) from RTT and control individuals to investigate the gene expression profile of IGF1 and IGF1R on different developmental stages of differentiation. We found that the thyroid hormone receptor (TRalpha 3) has a differential expression profile. Thyroid hormone is critical for normal brain development. Our results showed that there is a possible link between IGF1/IGF1R and the TRalpha 3 and that over expression of IGF1R in RTT cells may be the cause of neurites improvement in neural RTT-derived neurons.

Body composition and bone density reference data for Korean children, adolescents, and young adults according to age and sex: results of the 2009-2010 Korean National Health and Nutrition Examination Survey (KNHANES)

We established the timing of peak bone mass acquisition and body composition maturation and provide an age- and sex-specific body composition and bone density reference database using dual-energy X-ray absorptiometry in Korean subjects 10-25 years of age. Reference percentiles and curves were developed for bone mineral content (BMC), bone mineral density (BMD) of the whole body, the lumbar spine, and the femoral neck, and for fat mass (FM) and lean mass (LM) of 1969 healthy participants (982 males) who participated in the 2009-2010 Korean National Health and Nutrition Examination Survey. Additionally, bone mineral apparent density (BMAD), FM index, and LM index were calculated to adjust for body size. BMC and BMD at all skeletal sites as well as LM increased with age, reaching plateaus at 17-20 years of age in females and 20-23 years of age in males. The femoral neck was the first to reach a bone mass plateau, followed by the lumbar spine and then the whole body. Spine BMAD increased with age in both sexes, but femoral and whole-body BMAD remained the same over time. Females displayed a dramatic increase in FM during puberty, but the FM of males decreased until mid-puberty. These findings indicate that bone health and body composition should be monitored using a normal reference database until the late second to early third decade of life, when statural growth and somatic maturation are completed.

Age and growth of the midwater crocodile shark Pseudocarcharias kamoharai

Age and growth were analysed on the basis of 372 vertebrae from specimens of the crocodile shark Pseudocarcharias kamoharai (66·0-122·0 cm, total length, LT ) collected in the south-western Atlantic Ocean. Centrum edge analysis suggested the first four months of the year as the period of band completion, leading to acceptance of free-living bands as annual. A pre-birth ring is formed in embryos >31·0 cm LT , whereas the birthmark is deposited in newborns of 46·1 ± 1·1 cm LT (mean ± s.d.). Growth was parameterized using seven models and the AIC was used for selection of the most plausible model. The von Bertalanffy growth model received the greatest support from the data, providing the following growth parameters for combined sexes: L∞ = 129·2 cm, k = 0·137 year(-1) and t0 = -3·9 years. No significant differences were detected in growth by sex, but significant differences in age composition by sex were found in the sample. Overall age ranged from 2 to >13 years in females and from 1 to 8 years in males. Males achieved first maturity at 3·1 years and females at 5·1 years, with pregnancy appearing at 4·8 years. Similar to other lamnoid species, P. kamoharai is relatively fast growing.

Vertebral Development in Paleozoic and Mesozoic Tetrapods Revealed by Paleohistological Data

Basal tetrapods display a wide spectrum of vertebral centrum morphologies that can be used to distinguish different tetrapod groups. The vertebral types range from multipartite centra in stem-tetrapods, temnospondyls, and seymouriamorphs up to monospondylous centra in lepospondyls and have been drawn upon for reconstructing major evolutionary trends in tetrapods that are now considered textbook knowledge. Two modes of vertebral formation have been postulated: the multipartite vertebrae formed first as cartilaginous elements with subsequent ossification. The monospondylous centrum, in contrast, was formed by direct ossification without a cartilaginous precursor. This study describes centrum morphogenesis in basal tetrapods for the first time, based on bone histology. Our results show that the intercentra of the investigated stem-tetrapods consist of a small band of periosteal bone and a dense network of endochondral bone. In stereospondyl temnospondyls, high amounts of calcified cartilage are preserved in the endochondral trabeculae. Notably, the periosteal region is thickened and highly vascularized in the plagiosaurid stereospondyls. Among “microsaur” lepospondyls, the thickened periosteal region is composed of compact bone and the notochordal canal is surrounded by large cell lacunae. In nectridean lepospondyls, the periosteal region has a spongy structure with large intertrabecular spaces, whereas the endochondral region has a highly cancellous structure. Our observations indicate that regardless of whether multipartite or monospondylous, the centra of basal tetrapods display first endochondral and subsequently periosteal ossification. A high interspecific variability is observed in growth rate, organization, and initiation of periosteal ossification. Moreover, vertebral development and structure reflect different lifestyles. The bottom-dwelling Plagiosauridae increase their skeletal mass by hyperplasy of the periosteal region. In nectrideans, the skeletal mass decreases, as the microstructure is spongy and lightly built. Additionally, we observed that vertebral structure is influenced by miniaturization in some groups. The phylogenetic information that can be drawn from vertebral development, however, is limited.

TGFβ and BMP Dependent Cell Fate Changes Due to Loss of Filamin B Produces Disc Degeneration and Progressive Vertebral Fusions

Spondylocarpotarsal synostosis (SCT) is an autosomal recessive disorder characterized by progressive vertebral fusions and caused by loss of function mutations in Filamin B (FLNB). FLNB acts as a signaling scaffold by linking the actin cytoskleteon to signal transduction systems, yet the disease mechanisms for SCT remain unclear. Employing a Flnb knockout mouse, we found morphologic and molecular evidence that the intervertebral discs (IVDs) of Flnb^–/–mice undergo rapid and progressive degeneration during postnatal development as a result of abnormal cell fate changes in the IVD, particularly the annulus fibrosus (AF). In Flnb^–/–mice, the AF cells lose their typical fibroblast-like characteristics and acquire the molecular and phenotypic signature of hypertrophic chondrocytes. This change is characterized by hallmarks of endochondral-like ossification including alterations in collagen matrix, expression of Collagen X, increased apoptosis, and inappropriate ossification of the disc tissue. We show that conversion of the AF cells into chondrocytes is coincident with upregulated TGFβ signaling via Smad2/3 and BMP induced p38 signaling as well as sustained activation of canonical and noncanonical target genes p21 and Ctgf. These findings indicate that FLNB is involved in attenuation of TGFβ/BMP signaling and influences AF cell fate. Furthermore, we demonstrate that the IVD disruptions in Flnb^–/–mice resemble aging degenerative discs and reveal new insights into the molecular causes of vertebral fusions and disc degeneration.

Whereas there is a large foundation of knowledge concerning skeletal formation and development, identifying the molecular changes behind Intervertebral Disc (IVD) aging and degeneration has been a challenge. The loss of Filamin B, a protein component of the cell’s cytoskeletal structure, gives rise to Spondylocarpotarsal Synostosis, a rare genetic disorder characterized by fusions of the vertebral bodies. Similarly, mice lacking the Filamin B protein show fusions of the vertebral bodies. We found that these fusions are caused by the early degeneration and eventual ossification of the IVDs. Our study demonstrates that this degeneration is caused by the increase in TGFβ and BMP activity, developmental pathways essential in bone and cartilage formation. These findings represent a significant step forward in our understanding of the molecular basis of IVD degeneration. as well as revealing filamin B’s role in TGFβ/BMP signaling regulation. Moreover, we demonstrate that the study of the rare disease spondylocarpotarsal synostosis in a model organism can uncover mechanisms underlying more common diseases. Finally, our findings provide a model system that will facilitate further discoveries regarding disc degeneration, which affects a significant proportion of the population.

Serial elongation derotation flexion (EDF) casting for patients with infantile and juvenile scoliosis

Infantile and juvenile scoliosis, among different types of spinal deformity, is still a challenge for pediatric orthopedic surgeons. The ideal treatment of infantile and juvenile scoliosis has not yet been identified as both clinicians and surgeons still face multiple challenges, including preservation of the thoracic spine, thoracic cage, lung growth and cardiac function without reducing spinal motion. Elongation, derotation, flexion (EDF) casting technique is a custom-made thoracolumbar cast based on a three dimensional correction concept. This cast offers three-dimensional correction and can control the evolution of the deformity in some cases. Spinal growth can be guided by EDF casting as it can influence the initially curved spine to grow straighter. This article aimed to provide a comprehensive review of how infantile and juvenile scoliosis can affect normal spine and thorax and how these deformities can be treated with serial EDF casting technique. A current literature review is mandatory in order to understand the principles of the serial EDF casting technique and the effectiveness of conservative treatment in young and very young patients.

Estimating growth from tagging data: an application to north-east Atlantic tope shark Galeorhinus galeus

This study addresses the inherent uncertainty when estimating growth from limited mark-recapture information. A selection procedure was developed utilizing 18 competing growth estimation methods. The optimal method for a given data set was identified by simulating the length at capture and recapture under different scenarios of measurement error and growth variability while considering the structure of observed data. This selection procedure was applied to mark-recapture data for 37 female and 16 male tope sharks Galeorhinus galeus obtained from tagging studies in the north-east Atlantic Ocean. Parameter estimates differed strongly among methods, showing the need for careful method selection. The selection approach suggested that best estimates for males and females were given by James' weighted least-squares approach with a fixed asymptote. Given an average total length (LT) at birth of 28 cm, the von Bertalanffy growth function of north-east Atlantic G. galeus would be LT = 200·85 - (200·85 - 28)e(-0·076t) for females and LT = 177·30 - (177·30 - 28)e(-0·081t) for males. The resulting age estimates were up to 11 years lower when compared with previous estimates derived from highly uncertain vertebrae readings. More generally, this procedure can help identify optimal estimation methods for a given data set and therefore aid in estimating more reliable growth parameters from mark-recapture information.

Slow growth of the overexploited milk shark Rhizoprionodon acutus affects its sustainability in West Africa

Age and growth of Rhizoprionodon acutus were estimated from vertebrae age bands. From December 2009 to November 2010, 423 R. acutus between 37 and 112 cm total length (LT ) were sampled along the Senegalese coast. Marginal increment ratio was used to check annual band deposition. Three growth models were adjusted to the length at age and compared using Akaike's information criterion. The Gompertz growth model with estimated size at birth appeared to be the best and resulted in growth parameters of L∞ = 139.55 (LT ) and K = 0.17 year(-1) for females and L∞ = 126.52 (LT ) and K = 0.18 year(-1) for males. The largest female and male examined were 8 and 9 years old, but the majority was between 1 and 3 years old. Ages at maturity estimated were 5.8 and 4.8 years for females and males, respectively. These results suggest that R. acutus is a slow-growing species, which render the species particularly vulnerable to heavy fishery exploitation. The growth parameters estimated in this study are crucial for stock assessments and for demographic analyses to evaluate the sustainability of commercial harvests.

Development of the Synarcual in the Elephant Sharks (Holocephali; Chondrichthyes): Implications for Vertebral Formation and Fusion

The synarcual is a structure incorporating multiple elements of two or more anterior vertebrae of the axial skeleton, forming immediately posterior to the cranium. It has been convergently acquired in the fossil group ‘Placodermi’, in Chondrichthyes (Holocephali, Batoidea), within the teleost group Syngnathiformes, and to varying degrees in a range of mammalian taxa. In addition, cervical vertebral fusion presents as an abnormal pathology in a variety of human disorders. Vertebrae develop from axially arranged somites, so that fusion could result from a failure of somite segmentation early in development, or from later heterotopic development of intervertebral bone or cartilage. Examination of early developmental stages indicates that in the Batoidea and the ‘Placodermi’, individual vertebrae developed normally and only later become incorporated into the synarcual, implying regular somite segmentation and vertebral development. Here we show that in the holocephalan Callorhinchus milii, uniform and regular vertebral segmentation also occurs, with anterior individual vertebra developing separately with subsequent fusion into a synarcual. Vertebral elements forming directly behind the synarcual continue to be incorporated into the synarcual through growth. This appears to be a common pattern through the Vertebrata. Research into human disorders, presenting as cervical fusion at birth, focuses on gene misexpression studies in humans and other mammals such as the mouse. However, in chondrichthyans, vertebral fusion represents the normal morphology, moreover, taxa such Leucoraja (Batoidea) and Callorhinchus (Holocephali) are increasingly used as laboratory animals, and the Callorhinchus genome has been sequenced and is available for study. Our observations on synarcual development in three major groups of early jawed vertebrates indicate that fusion involves heterotopic cartilage and perichondral bone/mineralised cartilage developing outside the regular skeleton. We suggest that chondrichthyans have potential as ideal extant models for identifying the genes involved in these processes, for application to human skeletal heterotopic disorders.

The use of non-adult vertebral dimensions as indicators of growth disruption and non-specific health stress in skeletal populations

OBJECTIVE

Traditional methods of detecting growth disruption have focused on deficiencies in the diaphyseal length of the long bones. This study proposes the implementation of vertebral measurements (body height and transverse diameter of the neural canal) from non-adults (0-17 years) as a new methodology for the identification of growth disruption.

METHODS

Measurements of vertebral body height and transverse diameter were taken from 96 non-adult skeletons and 40 adult skeletons from two post-medieval sites in England (Bow Baptist, London and Coronation Street, South Shields). Non-adult measurements were plotted against dental age to construct vertebral growth profiles through which inter-population comparisons could be made.

RESULTS

Results demonstrated that both sites experienced some growth retardation in infancy, evident as deficiencies in transverse diameter. However, analysis of vertebral body height revealed different chronologies of growth disruption between the sites, with a later age of attainment of skeletal maturity recorded in the Bow Baptist sample.

DISCUSSION

These vertebral dimensions undergo cessation of growth at different ages, with transverse diameter being "locked-in" by ∼1-2 years of age, while vertebral body height may continue to grow into early adulthood. These measurements can therefore provide complementary information regarding the timing of growth disruption within archaeological populations. Non-adult vertebral measurements can increase our osteobiographical understanding of the timings of episodes of health stress, and allow for the analysis of growth when other skeletal elements are fragmentary.

Tissue regeneration and biomineralization in sea urchins: role of Notch signaling and presence of stem cell markers

Echinoderms represent a phylum with exceptional regenerative capabilities that can reconstruct both external appendages and internal organs. Mechanistic understanding of the cellular pathways involved in regeneration in these animals has been hampered by the limited genomic tools and limited ability to manipulate regenerative processes. We present a functional assay to investigate mechanisms of tissue regeneration and biomineralization by measuring the regrowth of amputated tube feet (sensory and motor appendages) and spines in the sea urchin, Lytechinus variegatus. The ability to manipulate regeneration was demonstrated by concentration-dependent inhibition of regrowth of spines and tube feet by treatment with the mitotic inhibitor, vincristine. Treatment with the gamma-secretase inhibitor DAPT resulted in a concentration-dependent inhibition of regrowth, indicating that both tube feet and spine regeneration require functional Notch signaling. Stem cell markers (Piwi and Vasa) were expressed in tube feet and spine tissue, and Vasa-positive cells were localized throughout the epidermis of tube feet by immunohistochemistry, suggesting the existence of multipotent progenitor cells in these highly regenerative appendages. The presence of Vasa protein in other somatic tissues (e.g. esophagus, radial nerve, and a sub-population of coelomocytes) suggests that multipotent cells are present throughout adult sea urchins and may contribute to normal homeostasis in addition to regeneration. Mechanistic insight into the cellular pathways governing the tremendous regenerative capacity of echinoderms may reveal processes that can be modulated for regenerative therapies, shed light on the evolution of regeneration, and enable the ability to predict how these processes will respond to changing environmental conditions.

Topography of spinal column and kidney receptors as illustrated by microsystem of the foot

OBJECTIVE

To test the accuracy of the distribution of reflective zones on the feet as proposed by William Fitzgerald using the spine and kidney receptors as reference points.

METHODS

Spine and feet lengths were measured first along straight lines and then again, taking into consideration the anatomical curves. The spinal column was further measured with regard to its individual regions (cervical, thoracic, lumbar, sacrum-coccyx). Straight-line measurements were taken with the help of an anthropometer. Measurements that took into account all of the curves were performed with the opisometer (also known as a "map measurer"). All the measurements were accurate to within 1 mm. The study subjects were a healthy, physically fit 16-year-old female student and a 53-year-old male office employee exposed to an average dose of physical exercise.

RESULTS

The kidney receptor in the foot did not reflect onto the predetermined lumbar section of the spinal column as measured along the straight line or with regard to curves. Instead, in both subjects the kidney receptor reflected onto the thoracic spine.

CONCLUSION

Te particular level of the spinal cord that innervates the given organ controls the distribution of receptors of individual organs in the foot.

Age and growth of the tiger shark Galeocerdo cuvier off the east coast of Australia

Total lengths (L(T)) at age and growth rates for south-west Pacific Galeocerdo cuvier were estimated from vertebral growth-band counts of 202 sagitally sectioned centra from 112 females (71-430 cm L(T)), 79 males (72-351 cm L(T)) and 11 of unknown sex. Captive growth data were also examined to complement vertebral age estimations. The sexes combined modelled growth coefficient (k = 0.08) was smaller than previously reported for G. cuvier populations elsewhere. Split-band and narrow banding patterns were identified as potential sources of age underestimation in this species.

Targeted Deletion of Btg1 and Btg2 Results in Homeotic Transformation of the Axial Skeleton

Btg1 and Btg2 encode highly homologous proteins that are broadly expressed in different cell lineages, and have been implicated in different types of cancer. Btg1 and Btg2 have been shown to modulate the function of different transcriptional regulators, including Hox and Smad transcription factors. In this study, we examined the in vivo role of the mouse Btg1 and Btg2 genes in specifying the regional identity of the axial skeleton. Therefore, we examined the phenotype of Btg1 and Btg2 single knockout mice, as well as novel generated Btg1^-/-;Btg2^-/- double knockout mice, which were viable, but displayed a non-mendelian inheritance and smaller litter size. We observed both unique and overlapping phenotypes reminiscent of homeotic transformation along the anterior-posterior axis in the single and combined Btg1 and Btg2 knockout animals. Both Btg1^-/- and Btg2^-/- mice displayed partial posterior transformation of the seventh cervical vertebra, which was more pronounced in Btg1^-/-;Btg2^-/- mice, demonstrating that Btg1 and Btg2 act in synergy. Loss of Btg2, but not Btg1, was sufficient for complete posterior transformation of the thirteenth thoracic vertebra to the first lumbar vertebra. Moreover, Btg2^-/- animals displayed complete posterior transformation of the sixth lumbar vertebra to the first sacral vertebra, which was only partially present at a low frequency in Btg1^-/- mice. The Btg1^-/-;Btg2^-/- animals showed an even stronger phenotype, with L5 to S1 transformation. Together, these data show that both Btg1 and Btg2 are required for normal vertebral patterning of the axial skeleton, but each gene contributes differently in specifying the identity along the anterior-posterior axis of the skeleton.

Age, growth and maturity of the pelagic thresher Alopias pelagicus and the scalloped hammerhead Sphyrna lewini

Indonesia has the greatest reported chondrichthyan catches worldwide, with c.110,000 t caught annually. The pelagic thresher (Alopias pelagicus) and scalloped hammerhead (Sphryna lewini) together comprise about 25% of the total catches of sharks landed in Indonesia. Age and growth parameters were estimated for A. pelagicus and S. lewini from growth-band counts of thin-cut vertebral sections. Alopias pelagicus (n = 158) and S. lewini (n = 157) vertebrae were collected from three Indonesian fish markets over a 5 year period. A multi-model analysis was used to estimate growth parameters for both species. The models of best fit for males and females for A. pelagicus was the three-parameter logistic (L∞ = 3169 mm LT , k = 0·2) and the two-parameter von Bertalanffy models (L∞ = 3281 mm LT , k = 0·12). Age at maturity was calculated to be 10·4 and 13·2 years for males and females, respectively, and these are the oldest estimated for this species. The samples of S. lewini were heavily biased towards females, and the model of best fit for males and females was the three-parameter Gompertz (L∞ = 2598 mm LT , k = 0·15) and the two-parameter Gompertz (L∞ = 2896 mm LT , k= 0·16). Age at maturity was calculated to be 8·9 and 13·2 years for males and females, respectively. Although numerous age and growth studies have previously been undertaken on S. lewini, few studies have been able to obtain adequate samples from all components of the population because adult females, adult males and juveniles often reside in different areas. For the first time, sex bias in this study was towards sexually mature females, which are commonly lacking in previous biological studies on S. lewini. Additionally, some of the oldest aged specimens and highest age at maturity for both species were observed in this study. Both species exhibit slow rates of growth and late age at maturity, highlighting the need for a re-assessment of the relative resilience of these two globally threatened sharks at current high levels of fishing mortality throughout the eastern Indian Ocean.

Maternal high-fat diet and offspring expression levels of vitamin K-dependent proteins

Studies suggest that bone growth and development and susceptibility to vascular disease in later life are influenced by maternal nutrition during intrauterine and early postnatal life. There is evidence for a role of vitamin K-dependent proteins (VKDPs) including osteocalcin, matrix Gla protein, periostin, and growth-arrest specific- protein 6, in both bone and vascular development. We have examined whether there are alterations in these VKDPs in bone and vascular tissue from offspring of mothers subjected to a nutritional challenge: a high-fat diet during pregnancy and postnatally, using 6-week-old mouse offspring. Bone site-specific and sex-specific differences across femoral and vertebral bone in male and female offspring were observed. Overall a high-fat maternal diet and offspring diet exacerbated the bone changes observed. Sex-specific differences and tissue-specific differences were observed in VKDP levels in aorta tissue from high-fat diet-fed female offspring from high-fat diet-fed mothers displaying increased levels of Gas6 and Ggcx compared with those of female controls. In contrast, differences were seen in VKDP levels in femoral bone of female offspring with lower expression levels of Mgp in offspring of mothers fed a high-fat diet compared with those of controls. We observed a significant correlation in Mgp expression levels within the femur to measures of bone structure of the femur and vertebra, particularly in the male offspring cohort. In summary, the current study has highlighted the importance of maternal nutrition on offspring bone development and the correlation of VKDPs to bone structure.

The MAGEC system for spinal lengthening in children with scoliosis: A NICE Medical Technology Guidance

Scoliosis-structural lateral curvature of the spine-affects around four children per 1,000. The MAGEC system comprises a magnetically distractible spinal rod implant and an external remote controller, which lengthens the rod; this system avoids repeated surgical lengthening. Rod implants brace the spine internally and are lengthened as the child grows, preventing worsening of scoliosis and delaying the need for spinal fusion. The Medical Technologies Advisory Committee at the National Institute for Health and Care Excellence (NICE) selected the MAGEC system for evaluation in a NICE medical technologies guidance. Six studies were identified by the sponsor (Ellipse Technologies Inc.) as being relevant to the decision problem. Meta-analysis was used to compare the clinical evidence results with those of one conventional growth rod study, and equal efficacy of the two devices was concluded. The key weakness was selection of a single comparator study. The External Assessment Centre (EAC) identified 16 conventional growth rod studies and undertook meta-analyses of relevant outcomes. Its critique highlighted limitations around study heterogeneity and variations in baseline characteristics and follow-up duration, precluding the ability to draw firm conclusions. The sponsor constructed a de novo costing model showing that MAGEC rods generated cost savings of £9,946 per patient after 6 years, compared with conventional rods. The EAC critiqued and updated the model structure and inputs, calculating robust cost savings of £12,077 per patient with MAGEC rods compared with conventional rods over 6 years. The year of valuation was 2012. NICE issued a positive recommendation as supported by the evidence (Medical Technologies Guidance 18).

Validated age, growth and maturity of the bonnethead Sphyrna tiburo in the western North Atlantic Ocean

The age, growth and maturity of bonnetheads Sphyrna tiburo inhabiting the estuarine and coastal waters of the western North Atlantic Ocean (WNA) from Onslow Bay, North Carolina, south to West Palm Beach, Florida, were examined. Vertebrae were collected and aged from 329 females and 217 males ranging in size from 262 to 1043 mm and 245 to 825 mm fork length, LF , respectively. Sex-specific von Bertalanffy growth curves were fitted to length-at-age data. Female von Bertalanffy parameters were L∞  = 1036 mm LF , k = 0·18, t0  = -1·64 and L0  = 272 mm LF . Males reached a smaller theoretical asymptotic length and had a higher growth coefficient (L∞  = 782 mm LF , k = 0·29, t0  = -1·43 and L0  = 266 mm LF ). Maximum observed age was 17·9 years for females and 16·0 years for males. Annual deposition of growth increments was verified by marginal increment analysis and validated for age classes 2·5+ to 10·5+ years through recapture of 13 oxytetracycline-injected specimens at liberty in the wild for 1-4 years. Length (LF50 ) and age (A50 ) at 50% maturity were 819 mm and 6·7 years for females, and 618 mm and 3·9 years for males. Both female and male S. tiburo in the WNA had a significantly higher maximum observed age, LF50 , A50 and L∞ , and a significantly lower k and estimated L0 than evident in the Gulf of Mexico (GOM). These significant differences in life-history parameters, as well as evidence from tagging and genetic studies, suggest that S. tiburo in the WNA and GOM should be considered separate stocks.

Dietary supplementation with long chain polyunsaturated fatty acids in pregnant guinea pigs has sex-dependent effects on growth and bone outcomes in offspring

Long chain PUFA enhance bone mass in non-pregnant mammals. We examined the effects of arachidonic (AA; 20:4n-6) and docosahexaenoic (DHA; 22:6n-3) acid on bone mass of mothers and neonates. Guinea pig sows (n=15) were fed control, DHA or AA+DHA diets from mating to weaning. Measurements included: osteocalcin (OC), deoxypyridinoline (DPD), areal bone mineral density (aBMD) in sows and neonates; and volumetric density (vBMD) in neonates. Only vertebral aBMD and OC:DPD ratio declined during reproduction and only DHA reduced OC:DPD. Male pup weight was reduced by DHA and female weight elevated by AA+DHA. Whole body and femur aBMD were reduced by DHA and AA+DHA; whereas tibia vBMD was reduced by DHA in males. Female whole body, tibia and vertebrae aBMD plus tibia vBMD were elevated by AA+DHA; and DHA elevated whole body, tibia and vertebrae aBMD. Dietary AA+DHA and DHA elicit sex-dependent effects on neonatal bone, with minimal impact on mothers.

[Abnormal growth of spine in patients with adolescent idiopathic thoracic scoliosis]

OBJECTIVE

To investigate if the growth patterns of the spine and pelvis are consistent in adolescent idiopathic scoliosis (AIS) patients with single thoracic curves.

METHODS

Forty-eight thoracic adolescent idiopathic scoliosis (T-AIS) female patients and 48 healthy age-matched adolescents were recruited consecutively between December 2011 and October 2012. Radiographic parameters including height of spine (HOS), length of spine (LOS), height of thoracic spine (HOT), length of thoracic spine (LOT), height of pelvis (HOP), width of pelvis (WOP) and width of thorax (WOT) were measured on the long-cassette posteroanterior standing radiographs. In addition, ratios including HOS/HOP, LOS/HOP, HOT/HOP, LOT/HOP, LOS/LOT, WOT/WOP were also calculated. Independent t-test was performed to compare the radiographic parameters and ratios between the two groups.

RESULTS

Compared to the age-matched healthy adolescents, T-AIS patients had a significantly higher LOS and LOT (t = -2.364 and -1.495, P = 0.020 and 0.043) and smaller HOS and HOT (t = 2.060 and 3.359, P = 0.042 and 0.001). Yet, all of HOP, WOP and WOT showed no significant difference between T-AIS patients and healthy adolescents. Similarly, LOS/HOP and LOT/HOP were significantly higher in T-AIS patients as may be expected with an average LOS/HOP of 2.26 ± 0.14 in normal controls.In addition, LOS/LOT in normal controls had a trend of increase with age which was different from the stable LOS/LOT in T-AIS patients, indicating an increased growth of thoracic vertebra compared to lumbar vertebra.

CONCLUSIONS

Compared to the age-matched healthy adolescents, T-AIS patients have an abnormal growth characteristics with longer spine. The growth of pelvis and thorax show no significant differences between T-AIS patients and healthy adolescents.

Surgical aspects of spinal growth modulation in scoliosis correction

Spine growth modulation for scoliosis correction is a technique for slowing growth on the convex side of the curve and enhancing growth on the concave side by using the Heuter-Volkmann principle; this results in gradual deformity correction. The theoretic advantages include speedier recovery because of the minimally invasive approach used, as well as motion preservation. Several devices have been used in humans, including vertebral body stapling, with either a flexible titanium clip or a nitinol staple, and anterior spinal tethering. Prerequisites for the use of these devices are a relatively flexible curve and sufficient remaining growth in the patient. Although vertebral body stapling is effective for moderate curves of less than 40°, anterior spinal tethering can be used for curves greater than 40°. The titanium clip and spinal tethers are used exclusively for thoracic scoliosis, whereas nitinol staples can be used for the thoracic spine or the lumbar spine. The thoracoscopic technique is used for thoracic instrumentation, and the mini-open retroperitoneal technique is used for lumbar staple insertion. The insertion of a titanium clip and an anterior spinal tether requires sacrifice and mobilization of the segmental vessels, whereas nitinol staples can be inserted without such sacrifice. Single lung ventilation and CO2 insufflation are used to improve visualization with the thoracoscope. The curve should be instrumented from an end vertebra to an end vertebra. Postoperative immobilization depends on the type of device used. Most complications are approach related, such as atelectasis caused by a mucus plug, pain at the chest tube site, and pneumothorax. Device-related complications are rare. Overcorrection is a concern. In patients with early onset scoliosis, a hybrid construct with vertebral stapling and growing rods or a vertical expandable prosthetic titanium rib has been suggested. A failure of the spinal growth modulation procedure does not preclude spinal fusion. None of the devices for spine growth modulation have been approved by the FDA for human use and are still investigational. Early results are promising, and continued clinical studies are necessary.