A Multivariate Study of Three Prehistoric Tennessee Skeletal Populations: Mouse Creek, Dallas, and Middle Cumberland

The purpose of this study was to employ the techniques of physical anthropology in the examination of an archaeological hypothesis set forth by Thomas M. N. Lewis and Madeline Kneberg in the 1940\u27s. This hypothesis concerned the possible Middle Tennessee origin of the Mouse Creek people. Mouse Creek cultural remains (e.g. settlement pattern, architecture, burial customs, and pottery) were judged to differ from their nearest contemporary neighbors, the Dallas, while showing certain similarities to the Middle Cumberland culture of Middle Tennessee. A multivariate statistical analysis using 22 craniofacial measurements was applied to skeletal material representing these three populations: the Mouse Creek and Dallas people from the eastern Tennessee Valley area and the Middle Cumberland people from the Cumberland Valley area in Middle Tennessee. The statistical approach used was that developed by Mahalanobis (1936), as modified by Goodman (1972). The resulting distances were expressed by Gower\u27s (1972) principal coordinate analysis. The three groups, as well as the individual sites from which they were composed, were analyzed. The biological distances indicate that the Mouse Creek males did not differ (at the 0.05 level) from either the Middle Cumberland or Dallas males. This was also the case for the Mouse Creek and Middle Cumberland females; however, the Mouse Creek females were distinct (at the 0.025 level) from the Dallas females. Similar relationships were also expressed by the individual sites. These results are supportive of the Lewis and Kneberg hypothesis and may further suggest a matrilocal kinship system for the three groups. These same relationships may also result from gene flow produced by political alliances and widespread trade and travel throughout the entire area. Such interactions would be stimulated by a common linguistic background. These two possibilities are not mutually exclusive. Both the metric and archaeological data support the Lewis and Kneberg hypothesis. However, gene flow from years of trade, travel, and alliances is also a likely factor

Predicting Meniscus Mechanical Properties using Quantitative Magnetization Transfer Magnetic Resonance Imaging

Osteoarthritis (OA) is a degenerative joint disease that affects the entire knee joint, afflicting approximately 13% of the Canadian population. The meniscus plays a key role in load bearing and stability of the knee joint, and its functionality is compromised throughout OA progression. Currently there does not exist a way to study the relationship between meniscal tissue degeneration and mechanical properties in vivo, but Quantitative Magnetization Transfer Magnetic Resonance Imaging (qMT MRI) is a quantitative MRI technique which may be a good candidate for this application. This is because qMT models soft tissues in a comparable way to how tissues are modeled mechanically, and qMT is dependent on water/macromolecule interactions similar to meniscal tissue functionality. The aim of this project is to assess whether qMT metrics – bound-pool fraction (f), magnetization exchange rate (k), and relaxation times of the free and bound pools (T1f, T2f, and T2b) – accurately predict experimentally-derived mechanical properties – aggregate modulus (Ha) and permeability (kp) – of excised meniscal samples. Six human cadaver knee specimens were imaged using qMT MRI techniques in order to obtain imaging metrics of the menisci. Subsequent to imaging, 59 core meniscal samples were tested using a stress relaxation approach in a confined compression testing configuration in order to obtain Ha and kp of the samples as measures of mechanical properties. A Spearman’s rho correlation was then performed on the mechanical properties and the imaging metrics of the core samples of the menisci to determine how well the imaging metrics predict the mechanical properties. One correlation, albeit weak, was found between mechanical properties and qMT metrics (Ha and T2b); however, this may be due to homogeneity in meniscal health of the specimens limiting the ability for correlations to be detected. Moderate to strong negative correlations between T1 relaxation time and f, and k were found. These relationships should be further explored as T1 is an often neglected imaging metric, and qMT in the meniscus is quite unexplored. T1 was found to have a moderate correlation with T2. These results reinforce that qMT is viable to use in the meniscus, but that further work needs to be done in order to determine if it can be used as a non-invasive method of assessing meniscal tissue mechanical properties

A Multivariate Study of Three Prehistoric Tennessee Skeletal Populations: Mouse Creek, Dallas, and Middle Cumberland

The purpose of this study was to employ the techniques of physical anthropology in the examination of an archaeological hypothesis set forth by Thomas M. N. Lewis and Madeline Kneberg in the 1940\u27s. This hypothesis concerned the possible Middle Tennessee origin of the Mouse Creek people. Mouse Creek cultural remains (e.g. settlement pattern, architecture, burial customs, and pottery) were judged to differ from their nearest contemporary neighbors, the Dallas, while showing certain similarities to the Middle Cumberland culture of Middle Tennessee. A multivariate statistical analysis using 22 craniofacial measurements was applied to skeletal material representing these three populations: the Mouse Creek and Dallas people from the eastern Tennessee Valley area and the Middle Cumberland people from the Cumberland Valley area in Middle Tennessee. The statistical approach used was that developed by Mahalanobis (1936), as modified by Goodman (1972). The resulting distances were expressed by Gower\u27s (1972) principal coordinate analysis. The three groups, as well as the individual sites from which they were composed, were analyzed. The biological distances indicate that the Mouse Creek males did not differ (at the 0.05 level) from either the Middle Cumberland or Dallas males. This was also the case for the Mouse Creek and Middle Cumberland females; however, the Mouse Creek females were distinct (at the 0.025 level) from the Dallas females. Similar relationships were also expressed by the individual sites. These results are supportive of the Lewis and Kneberg hypothesis and may further suggest a matrilocal kinship system for the three groups. These same relationships may also result from gene flow produced by political alliances and widespread trade and travel throughout the entire area. Such interactions would be stimulated by a common linguistic background. These two possibilities are not mutually exclusive. Both the metric and archaeological data support the Lewis and Kneberg hypothesis. However, gene flow from years of trade, travel, and alliances is also a likely factor

Crystal nucleation mechanism in melts of short polymer chains under quiescent conditions and under shear flow

We present a molecular dynamics simulation study of crystal nucleation from undercooled melts of n-alkanes, and we identify the molecular mechanism of homogeneous crystal nucleation under quiescent conditions and under shear flow. We compare results for n-eicosane(C20) and n-pentacontahectane(C150), i.e. one system below the entanglement length and one above. Under quiescent conditions, we observe that entanglement does not have an effect on the nucleation mechanism. For both chain lengths, the chains first align and then straighten locally. Then the local density increases and finally positional ordering sets in. At low shear rates the nucleation mechanism is the same as under quiescent conditions, while at high shear rates the chains align and straighten at the same time. We report on the effects of shear rate and temperature on the nucleation rates and estimate the critical shear rates, beyond which the nucleation rates increase with the shear rate. We show that the viscosity of the system is not affected by the crystalline nuclei.Comment: 9 page

Rescaling Relations between Two- and Three-dimensional Local Porosity Distributions for Natural and Artificial Porous Media

Local porosity distributions for a three-dimensional porous medium and local porosity distributions for a two-dimensional plane-section through the medium are generally different. However, for homogeneous and isotropic media having finite correlation-lengths, a good degree of correspondence between the two sets of local porosity distributions can be obtained by rescaling lengths, and the mapping associating corresponding distributions can be found from two-dimensional observations alone. The agreement between associated distributions is good as long as the linear extent of the measurement cells involved is somewhat larger than the correlation length, and it improves as the linear extent increases. A simple application of the central limit theorem shows that there must be a correspondence in the limit of very large measurement cells, because the distributions from both sets approach normal distributions. A normal distribution has two independent parameters: the mean and the variance. If the sample is large enough, LPDs from both sets will have the same mean. Therefore corresponding distributions are found by matching variances of two- and three-dimensional local porosity distributions. The variance can be independently determined from correlation functions. Equating variances leads to a scaling relation for lengths in this limit. Three particular systems are examined in order to show that this scaling behavior persists at smaller length-scales.Comment: 15 PostScript figures, LaTeX, To be published in Physica

The architecture of amyloid-like peptide fibrils revealed by X-ray scattering, diffraction and electron microscopy

Structural analysis of protein fibrillation is inherently challenging. Given the crucial role of fibrils in amyloid diseases, method advancement is urgently needed. A hybrid modelling approach is presented enabling detailed analysis of a highly ordered and hierarchically organized fibril of the GNNQQNY peptide fragment of a yeast prion protein. Data from small-angle X-ray solution scattering, fibre diffraction and electron microscopy are combined with existing high-resolution X-ray crystallographic structures to investigate the fibrillation process and the hierarchical fibril structure of the peptide fragment. The elongation of these fibrils proceeds without the accumulation of any detectable amount of intermediate oligomeric species, as is otherwise reported for, for example, glucagon, insulin and [alpha]-synuclein. Ribbons constituted of linearly arranged protofilaments are formed. An additional hierarchical layer is generated via the pairing of ribbons during fibril maturation. Based on the complementary data, a quasi-atomic resolution model of the protofilament peptide arrangement is suggested. The peptide structure appears in a [beta]-sheet arrangement reminiscent of the [beta]-zipper structures evident from high-resolution crystal structures, with specific differences in the relative peptide orientation. The complexity of protein fibrillation and structure emphasizes the need to use multiple complementary methods

Regional Variations in Physical Fitness and Activity in Healthy and Overweight Ecuadorian Adolescents

Background: Insufficient physical activity (PA) and excessive sedentary behavior (SB) are the main contributors to adolescent obesity. However, it is uncertain whether recent economic growth and urbanization in Ecuador are contributing to an obesogenic environment. This study assessed the relationships among fitness, PA, SB, and perceived social support for PA in adolescents from urban (Quito) and rural (Loja) Ecuador. Methods: Fitness was estimated using 3-min step test and PA and SB participation and social support for PA were self-reported in 407 adolescents. T-tests and analysis of variance assessed differences by sex, obesity status, and region of Ecuador. Pearson correlations assessed relationships among PA, SB, fitness, and social support. Results: Males and rural adolescents (48.3 ± 9.4 and 47.1 ± 9.6 mL/kg/min) were more fit than females and urban adolescents (41.1 ± 7.5 and 39.7 ± 6.1 mL/kg/min). Fitness was negatively correlated with obesity only in rural Ecuador. Few adolescents reported ≥60 min/day of PA (8.4%) or ≤2 h/day of SB (30.2%), with greater SB participation in rural Ecuador. Weak correlations were observed among fitness, PA, SB, and parental/peer support for PA (r = −0.18 to 0.19; p \u3c 0.05). Conclusion: While fitness varied by sex, weight status, and region, SB participation and parent/peer support for PA, not PA participation itself, predicted fitness in rural Ecuadorean adolescents

Odkrycie i zastosowanie pegwisomantu: antagonisty hormonu wzrostu

Growth hormone (GH) is a well established participant in several complex physiological processes including growth, differentiation, and metabolism. Recombinant human GH is a drug that has been approved for use for several clinical conditions where the action of GH is diminished or completely lacking. Thus there is considerable interest in developing novel drugs that modify the function of GH. Only in the last several decades have the detailed structural features of GH along with its interaction with its receptor been elucidated. In this review we summarise the basic structural and functional properties of GH, its receptor and their interaction. In addition, we discuss the discovery and development of an effective GH receptor antagonist, pegvisomant, and summarise potential therapeutic uses of this drug. (Pol J Endocrinol 2007; 58 (4): 322-329)Hormon wzrostu (GH, growth hormone) uczestniczy w wielu fizjologicznych procesach dotyczących wzrastania, różnicowania i metabolizmu. Leczenie rekombinowanym ludzkim GH jest akceptowane w wielu schorzeniach wiążących się z całkowitym brakiem lub zmniejszeniem działania GH. Wynika stąd znaczne zainteresowanie rozwojem nowych leków mogących modyfikować czynność GH. Dopiero niedawno wyjaśniono dokładną strukturę GH i jego interakcje z receptorem. W niniejszej pracy autorzy podsumowują wiedzę dotyczącą podstawowej budowy GH, jego receptora i interakcji między nimi. Ponadto, omówiono odkrycie i rozwój skutecznego antagonisty receptora GH, pegvisomantu i przedstawiono potencjalne możliwości zastosowania terapeutycznego tego leku