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Postero-anterior (PA) mobilization is widely used to manage low back pain by physiotherapists. The PA load is applied through the spinous process of a vertebra. Low bone density is a counter-indication of PA mobilization, whether PA mobilization may cause fractures in fragile vertebrae is unclear. Therefore, the aim of this study was to quantify the role of bone density on a fracture risk in the first lumbar vertebra subjected to PA load. A finite element model of the first lumbar (L1) vertebra of an elderly female was created to predict the fracture risk of the PA mobilization. The von Mises stress and minimum principal strain were used as the assessment indicators. Three different bone density cases were evaluated to reflect healthy, osteoporotic, and severe osteoporotic conditions by assuming heterogeneous moduli based on local bone density converted from computed tomographic images. In the severe osteoporotic condition under PA load, the maximum von Mises stress and largest compressive strain occurred in the pedicles and spinous process. These stress and strain exceeded the yield stress and yield strain indicating a high risk for failure. The resulted stress and strain were also excessive in the pedicles for healthy and moderate osteoporotic conditions. PA mobilization can increase the risk of vertebra fracture in elderly with osteoporosis. The pedicles and spinous process of osteoporotic L1 vertebra are the critical regions prone to fracture. We recommend that it is crucial to be reduce force when applying the PA mobilization to elderly with osteoporosis.

Hormonal changes during lactation are associated with profound changes in bone cell biology, such as osteocytic osteolysis, resulting in larger lacunae. Larger lacuna shape theoretically enhances the transmission of mechanical signals to osteocytes. We aimed to provide experimental evidence supporting this theory by comparing the mechanoresponse of osteocytes in the bone of lactating mice, which have enlarged lacunae due to osteocytic osteolysis, with the response of osteocytes in bone from age-matched virgin mice. The osteocyte mechanoresponse was measured in excised fibulae that were cultured in hormone-free medium for 24 h and cyclically loaded for 10 min (sinusoidal compressive load, 3000 µε, 5 Hz) by quantifying loading-related changes in Sost mRNA expression (qPCR) and sclerostin and β-catenin protein expression (immunohistochemistry). Loading decreased Sost expression by ~ threefold in fibulae of lactating mice. The loading-induced decrease in sclerostin protein expression by osteocytes was larger in lactating mice (55% decrease ± 14 (± SD), n = 8) than virgin mice (33% decrease ± 15, n = 7). Mechanical loading upregulated β-catenin expression in osteocytes in lactating mice by 3.5-fold (± 0.2, n = 6) which is significantly (p

Type 2 diabetes mellitus (T2DM) is a metabolic disorder associated with obesity and hyperglycemia. Roux-en-Y gastric bypass (RYGB) surgery is a common treatment for severely obese patients and T2DM. Both RYGB and T2DM are linked to increased skeletal fragility, though the exact mechanisms are poorly understood. Our aim was to characterize the structural, mechanical and compositional properties of bones from diet-induced obese and RYGB-treated obese (bypass) mice to elucidate which the exact factors are contributing to the increased skeletal fragility. To achieve this, a combinatory approach including microfocus X-ray computed tomography, 3-point bending, finite element modeling and Raman spectroscopy, was used. Compared to aged-matched lean controls, the obese mice displayed decreased cortical thickness, trabecular bone loss, decreased stiffness and increased Young’s modulus. For the bypass mice, these alterations were even more pronounced, and additionally they showed low mineral-to-matrix ratio in the cortical endosteal area. Accumulation of the advanced glycation end-product (AGE) pentosidine was found in the cortex of obese and bypass groups and this accumulation was correlated with an increased Young’s modulus. In conclusion, we found that the increased fracture risk in T2DM- and post-RYGB bones is mainly driven by accumulation of AGEs and macro-structural alterations, generating biomechanical dysfunctionality. ispartof: Scientific Reports vol:8 issue:1 pages:5881-1 ispartof: location:England status: published

Biomechanics and Modeling in Mechanobiology, 11 (5), ISSN:1617-7959, ISSN:1617-7940

Bone strain is considered one of the factors inducing bone tissue response to loading. Nevertheless, where animal studies can provide detailed data on bone response, they only offer limited information on experimental bone strains. Including micro-CT-based finite element (micro FE) models in the analysis represents a potent methodology for quantifying strains in bone. Therefore, the main objective of this study was to develop and validate specimen-specific micro FE models for the assessment of bone strains in the rat tibia compression model. Eight rat limbs were subjected to axial compression loading; strain at the medio-proximal site of the tibiae was measured by means of strain gauges. Specimen-specific micro FE models were created and analyzed. Repeated measurements on each limb indicated that the effect of limb positioning was small (COV = 6.45 ± 2.27 %). Instead, the difference in the measured strains between the animals was high (54.2%). The computational strains calculated at the strain gauge site highly correlated to the measured strains (R (2) = 0.95). Maximum peak strains calculated at exactly 25% of the tibia length for all specimens were equal to 435.11 ± 77.88 microstrains (COV = 17.19%). In conclusion, we showed that strain gauge measurements are very sensitive to the exact strain gauge location on the bone; hence, the use of strain gauge data only is not recommended for studies that address at identifying reliable relationships between tissue response and local strains. Instead, specimen-specific micro FE models of rat tibiae provide accurate estimates of tissue-level strains.

Between about 500 a.d. and the late nineteenth century, clay cooking pots associated with the Thule culture were produced in the Arctic region. Ethnographic and archaeological records indicate that these vessels were typically underfired (often even unfired), highly porous, and easily broken. Despite these characteristics, the evidence indicates that they were used to heat water over open fires. In this paper, we examine how Arctic potters were able to produce unsintered vessels capable of holding liquids without disintegrating. We conclude that the application of seal oil and seal blood to the pot’s surface was the key to their success.

Although biomedical imaging technology is now readily available, few attempts have been made to expand the capabilities of these systems by adding not only quantitative but also functional analysis tools combining microimaging with time-lapsed mechanical testing. An area of special interest is multiscale functional imaging of trabecular bone to assess the relative importance of bone "quality" in the assessment of the mechanical competence of bone. First, relevant studies dealing with hierarchical imaging of trabecular bone and classic analyses such as quantitative morphometry and finite-element analysis to predict bone strength are reviewed. Second, studies are presented investigating failure mechanisms of three-dimensional trabecular bone through dynamic, time-lapsed microimaging, including image-guided techniques developed for this purpose and utilizing microcompression. For the first time, these allow the direct three-dimensional visualization and quantification of failure initiation and progression at the microstructural level.

irst-trimester screening for Down syndrome has become a commonly used approach in prenatal genetic diagnosis. The drive behind the development of earlier, reliable methods of genetic screening and risk assessment is the ability to provide the parents with more options at an earlier gestational age. Currently, this involves the sonographic evaluation of fetal nuchal translucency (NT) in combination with maternal serum levels of free beta-hCG and PAPP-A to provide a risk assessment for Down syndrome.1 This is referred to as combined first-trimester screening. Based on a survey of US maternal-fetal medicine specialists in 2001, of the 543 respondents, 46% used NT sonography and 27% used first-trimester maternal serum screening for Down syndrome.3 The term "nuchal translucency" refers to the fluid-filled space between the back of the fetal neck and the overlying skin.4 It has been noted that fetuses with Down syndrome, as well as other forms of aneuploidy, have increased edema in this area, resulting in an increased NT measurement.4 Based on seminal work by Nicolaides and others, measurement ofNT in fetuses between 11 and 14 weeks has been used since the early 1990's to provide earlier risk assessment of fetuses with aneuploidy.5 Initial results indicated detection rates comparable to second-trimester maternal serum screening.' However, three recent large trials, including the US-based Firstand SecondTrimester Evaluation of Risk (FASTER) trial, the North American-based First Trimester Maternal Serum Biochemistry and Ultrasound Fetal Nuchal Translucency Screening (BUN) Study, and the European-based Serum, Urine, and Ultrasound Screening Study (SURUSS) Trial have demonstrated that combined screening in the first trimester outperforms both NT and first-trimester serum screening when performed separately, with detection rates for Down syndrome ranging from 79%87% at a false positive rate of 5% 6 This compares favorably with performance of second-trimester serum screening, also referred to as the "quad" screen, which utilizes maternal serum levels of unconjugated estriol, free human chorionic gonadotropin, alpha-fetoprotein, and inhibin A, with a detection rate of 81%.7 Furthermore, the detection rate for trisomy 18 with the combined screen was comparable to the quad screen.8 There are still a number of issues which limit the use ofNT. The technical expertise required to obtain reliable and reproducible images has proven challenging. Furthermore, patients must have access to providers who are capable of performing first-trimester chorionic villus sampling when a patient screens positive. There is still no consensus as to the most efficient or

Previous research suggested that the chemical composition of rock varnish, a micrometer thick Si/AI/Mn/Fe coating, changed predictably through time and so could be used as a chronometer. In particular, the cation ratio, (Ca+K)/Ti, was posited to decrease as the varnish aged. However, many earlier varnish studies were not well documented and were based on chemical analyses now shown to be inaccurate. This paper describes a test and the first direct comparison between two different analytic methods used previously to “cation-ratio date” archeologic and geologic materials. It provides methodology sufficiently detailed for replication of analytical and sampling techniques.Our analyses of rock varnish from a prehistoric chert quarry in California show that the two principal methods used to “cation-ratio date” rock varnish generate consistently different elemental abundances and are therefore not comparable. Neither analytic method produced a significant time-dependent trend in varnish chemistry, suggesting rock varnish cation ratios are not a reproducible and thus probably not a reliable way to date lithic artifacts.

A Briton's educational level, social class, sex and age all go to determine the degree of linguistic difficulty which he finds acceptable in reading matter. Tables show how these determinants of acceptability relate to readability as measured by word and sentence lengths. It is hypothesised that long sentences are difficult because comprehension depends upon combining cortical patterns evoked by grammatically related elements; but in long sentences the pattern evoked by one element may have decayed before the next related element is read. Long words may cause difficulty because they are generally the more precise words, requiring longer to categorise semantically; but the longer the search for a word's meaning, the more likely that the preceding context will be lost beyond recall.

The Charles H. Herty, Jr. Award is presented for the best paper presented at the annual National Open Hearth and Basic Oxygen Steel Conference, and published in the Conference Proceedings. The award was established in 1960 to honor Charles H. Herty, Jr., distinguished physical chemist working in the field of iron and steel technology.

ALL stages of the desert locust Schistocerca gregaria are infected with a eugregarine Gregarina garnhami1,2 (Fig. 1a). The morphology and life history of gregarines have been studied extensively, but little is known about the effects of gregarines on their invertebrate hosts.