Testing the accuracy of different A-axis types for measuring the orientation of bones in the archaeological and paleontological record.

Orientation of archaeological and paleontological materials plays a prominent role in the interpretation of site formation processes. Allochthony and authochthony are frequently assumed from orientation patterns or lack thereof. Although it is still debated to what extent orientation of items can be produced in original depositional contexts, the recent use of GIS tools to measure orientations has highlighted several ways of reproducing A-axes with which to address these taphonomic issues. In the present study, the three most relevant A-axis types are compared to test their accuracy in reproducing water current direction. Although results may be similar in specific bone shapes, differences are important in other shapes. As known in engineering working with wind and fluid mechanics (developing shape optimization), longitudinal symmetrical axes (LSA) are the one that best orient structures against or in the same direction of wind and water. The present work shows that this is also the case for bones (regardless of shape), since LSA produce the most accurate estimates of flow direction. This has important consequences for the interpretation of orientation patterns at sites, since this type of axis is still not properly reproduced by GIS available tools.

From toe to head: use of robust regression methods in stature estimation based on foot remains.

Stature estimation is a standard procedure in the fields of forensic and biological anthropology, bio-archaeology and paleoanthropology, in order to gain biological insights into the individuals/populations studied. The most accurate stature estimation method is based on anatomical reconstruction (i.e., the Fully method), followed by type I regression equations (e.g., ordinary least squares - OLS) based on long bones, preferably from the lower limb. In some cases, due to the fragmentary nature of the osseous material recovered, stature estimates have to rely on other elements, such as foot remains. In this study, we explore stature estimation based on different foot bones: the talus, calcaneus, and metatarsals 1-4 in Afro- and Euroamericans of both sexes. The approach undertaken in this study is novel for two reasons. First, individual estimates for each bone are provided, and tarsals and metatarsals are combined in order to obtain more accurate estimates. Second, robust statistical methods based on type I regression equations are used, namely least trimmed squares (LTS). Our results show that the best individual bones for estimating stature are the first and second metatarsal and both the talus and the calcaneus. The combination of a tarsal and a metatarsal bone slightly improves the accuracy of the stature estimate.

Comparison of six statistics of genetic association regarding their ability to discriminate between causal variants and genetically linked markers.

OBJECTIVES: Genome-wide association (GWA) studies still rely on the common-disease common-variant hypothesis since the assumption is associated with increased power. In GWA studies, polymorphisms are genotyped and their association with disease is investigated. Most of the identified associations are indirect and reflect a shared inheritance of the genotyped markers and genetically linked causal variants. We have compared six statistics of genetic association regarding their ability to discriminate between markers and causal susceptibility variants, including a probability value (Pval) and a Bayes Factor (BF) based on logistic regression, and the attributable familial relative risk (FRR). METHODS: We carried out a simulation-based sensitivity analysis to explore several conceivable scenarios. Theoretical results were illustrated by established causal associations with age-related macular degeneration and by using imputed data based on HapMap for a case-control study of breast cancer. RESULTS: Our data indicate that a representation of genetic association by FRRs and BFs generally facilitates the distinction of causal variants. The FRR showed the best discriminative power under most investigated scenarios, but no single statistic outperformed the others in all situations. For example, rare moderate- to low-penetrance variants (allele frequency: 1%, dominant odds ratio: ≤2.0) seem to be best discriminated by BFs. CONCLUSIONS: Present results may help to fully utilize the data generated in association studies that take advantage of next generation sequencing and/or multiple imputation based on the 1000 Genomes Project.

Bilateral optic neuritis in a 26-year-old man with common variable immunodeficiency: a case report.

INTRODUCTION: Common variable immunodeficiency encompasses a group of heterogeneous conditions linked by a lack of immunoglobulin production and primary antibody failure. Although primary immunodeficiencies are typically characterized by recurrent infections, autoimmune manifestations have increasingly been recognized. Neurological complications are extremely rare and to the best of our knowledge optic neuritis has not been described previously. We report the case of a patient with common variable immunodeficiency who developed loss of vision secondary to bilateral optic neuritis. CASE PRESENTATION: A 26-year-old Caucasian man with a diagnosis of common variable immunodeficiency presented to our facility with loss of vision secondary to bilateral optic neuritis. Results of a thorough study for infectious, neoplastic and autoimmune diseases were negative. Our patient was treated with intravenous methylprednisolone with almost complete improvement and he remained asymptomatic at a 12-month follow-up. CONCLUSIONS: Bilateral optic neuritis should be added to the list of autoimmune disorders related to common variable immunodeficiency. If a patient with common variable immunodeficiency experiences loss of vision, the possibility of bilateral optic neuritis should be considered as rapid initiation of high-dose corticosteroids may improve visual recovery.