Human Bone Samples Research Articles

Relation between mechanical and densimetric properties to fractal dimension in human rib cortical bone

Numerous prior studies hypothesized a power-law relationship (E∝ρα) between cortical bone Young's modulus (E) and density (ρ) with an exponent 2.3≤α≤3.0, that has not been previously justified in the literature on a theoretical level. Moreover, despite the fact microstructure have been extensively studied, the material correlate of Fractal Dimension (FD) as a descriptor of bone microstructure was not clear in previous studies. This study examined the effect of mineral content and density on the mechanical properties of a large number of human rib cortical bone samples. The mechanical properties were calculated using Digital Image Correlation and uniaxial tensile tests. CT scans were used to calculate the Fractal Dimension (FD) of each specimen. For each specimen, the mineral (fmin), organic (forg) and water (fwat) weight fractions were determined. In addition, density was measured after a drying-and-ashing process. Then, Regression Analysis was employed to investigate the relationship between anthropometric variables, weight fractions, density, and FD, as well as its impact on the mechanical properties. Young's modulus exhibited a power-law relationship with an exponent of α>2.3 when using the conventional density (wet density), but α=2 when using dry density (desecated specimens). In addition, FD increases with decreasing cortical bone density. A significant relationship has been found between FD and density, whereby FD is correlated with the embedding of low density regions in cortical bone. This study provides a new insight in the exponent value of the power-law relation between Young's Modulus and density, and relates bone behavior with the fragile fracture theory in ceramic materials. Moreover, the results suggest that Fractal Dimension is related to presence of low-density regions.

Application of the microtomography technique in density studies of prehistoric and historical human skeletal materials

AbstractBone density is not a standard parameter examined during anthropological analysis, although researchers increasingly attempt to assess bone mineral density (BMD) in prehistoric populations. Computed tomography (CT) has great potential in this type of research. Micro CT is a precise and universal tool for bone density measurement based on CT value (attenuation factor of the X‐rays at a given point in space). Thirty‐four archaeological human radial bone samples from four chronologically and geographically different sites from southern Poland were examined here. Real BMD was measured (mass/volume) and compared with BMD obtained with the use of CT value results to verify correlation between those two parameters. The micro CT density values were estimated with an uncertainty of less than 0.03 g/cm3 in more than 75% of samples. This method does not require any special sample preparation and any substitute of soft tissues. This technique enables measurement of the cortical and cancellous bone separately in even partial or damaged bones.

Correlation between RF signal first-arrival and minimum spectral transit time in cancellous bone

Measurement of the singular ultrasound velocity of a homogeneous sample may be calculated by division of its thickness and propagation transit time, generally utilizing a detection criterion of an RF signal’s first-arrival. A porous composite sample composed of two materials of differing ultrasound velocity will however exhibit a range of transit times. Ultrasound transit time spectroscopy (UTTS) considers propagation of an array of sonic-rays, with minima and maxima values ranging from entire higher and lower velocity materials, respectively. The aim of this Technical Note is to test the hypothesis that conventional RF signal transit time measurement correlates with the minimum spectral transit time, utilizing previously obtained experimental data from human cancellous bone samples. Linear regression yielded a coefficient of determination (R2) of 94%. The authors consider a practical consequence of the hypothesis is that information on the variability of transit time within a heterogeneous test sample may be better assessed by UTTS than conventional RF first-arrival transit time measurement. Noting the fundamental relationships between transit time, velocity, and elasticity of a test sample, there is further potential for UTTS to describe both velocity and elasticity spectroscopies within a wide range of structurally complex composites.

Tracing microbial communities associated with archaeological human samples in Latvia, 7-11th centuries AD.

In the grave environment, microorganisms are major ecological participants in the successional decomposition of vertebrates and could infiltrate the skeleton/skeletal material during taphonomic processes. The diversity of archaeological skeleton-associated microbial assemblages and the impact of various factors are poorly understood. This study aimed to evaluate the taxonomic microbial composition of archaeological human bone and teeth samples from the 7th to 11th centuries AD from two burial sites in Latvia. Samples were analysed by a shotgun metagenomics-based approach. The results showed a strong presence of the environmental DNA in the samples, and variability in microbial community structure between individual samples. Differences in microbial composition were observed between bone and tooth samples, as well as between different burial sites. Furthermore, the presence of endogenous ancient DNA (aDNA) in tooth samples was detected. Overall, compositions of microbial communities associated with archaeological human remains in Latvia dated 7-11th century AD were influenced by the sample type and burial location. These findings indicate that, while the content of historical DNA in archaeological samples is low, the comparison of archaeological skeleton-associated microbial assemblages across time and space, along with aDNA damage profile analysis, is important and could help to reveal putative ancient microorganisms.

DNA methylation analysis identifies key transcription factors involved in mesenchymal stem cell osteogenic differentiation

BackgroundKnowledge about regulating transcription factors (TFs) for osteoblastogenesis from mesenchymal stem cells (MSCs) is limited. Therefore, we investigated the relationship between genomic regions subject to DNA-methylation changes during osteoblastogenesis and the TFs known to directly interact with these regulatory regions.ResultsThe genome-wide DNA-methylation signature of MSCs differentiated to osteoblasts and adipocytes was determined using the Illumina HumanMethylation450 BeadChip array. During adipogenesis no CpGs passed our test for significant methylation changes. Oppositely, during osteoblastogenesis we identified 2462 differently significantly methylated CpGs (adj. p < 0.05). These resided outside of CpGs islands and were significantly enriched in enhancer regions. We confirmed the correlation between DNA-methylation and gene expression. Accordingly, we developed a bioinformatic tool to analyse differentially methylated regions and the TFs interacting with them. By overlaying our osteoblastogenesis differentially methylated regions with ENCODE TF ChIP-seq data we obtained a set of candidate TFs associated to DNA-methylation changes. Among them, ZEB1 TF was highly related with DNA-methylation. Using RNA interference, we confirmed that ZEB1, and ZEB2, played a key role in adipogenesis and osteoblastogenesis processes. For clinical relevance, ZEB1 mRNA expression in human bone samples was evaluated. This expression positively correlated with weight, body mass index, and PPARγ expression.ConclusionsIn this work we describe an osteoblastogenesis-associated DNA-methylation profile and, using these data, validate a novel computational tool to identify key TFs associated to age-related disease processes. By means of this tool we identified and confirmed ZEB TFs as mediators involved in the MSCs differentiation to osteoblasts and adipocytes, and obesity-related bone adiposity.

FIRST RADIOCARBON DATING OF NEOLITHIC STONE CIST GRAVES FROM THE AOSTA VALLEY (ITALY): INSIGHTS INTO THE CHRONOLOGY AND BURIAL RITES OF THE WESTERN ALPINE REGION

ABSTRACTPrevious research on the Neolithic cist graves of the Western Alpine region—also known under the term Chamblandes type graves—mostly focused on sites located in western Switzerland and eastern France. For the adjacent Aosta Valley (Italy), only a little information is available. Within the framework of our research project, it was possible to identify about 120 stone cist graves from 10 sites in the Aosta Valley. Due to the lack of distinctive grave goods and missing absolute dating, however, their chronological position has been unclear until now. Here we present the first extensive series of radiocarbon dates from Neolithic stone cist graves of the Aosta Valley. We analyzed 31 human bone samples from four sites, and most dates indicate an unexpected early chronological position around the first half of the 5th millennium BCE, in particular, the site of Villeneuve, dating to 4800–4550 cal BCE. This identifies these burials from the Aosta Valley as belonging to the oldest known Neolithic cist graves of the Western Alpine region discovered so far. Altogether, our study provides new evidence allowing the first time to clarify the chronology of these sites and trace the evolution of this burial practice in the Western Alps.

Determination of the Modulus of Elasticity by Bending Tests of Specimens with Nonuniform Cross Section

BackgroundBending tests offer technical advantages when material testing is performed to determine the modulus of elasticity. In biomechanical studies, beam-like cortical bone specimens subjected to flexural loading are usually characterized by nonuniform cross-sectional properties along the beam axis and a comparatively large spatial variation of the local material properties.ObjectiveA suitable evaluation method for determining the average modulus of elasticity within the volume of beam-like specimens with nonuniform cross section was to be identified.MethodsA total of 138 samples of human pelvic cortical bone were extracted and tested under flexural loading. Different methods, all based on the linear-elastic flexural theory of beams, were applied to determine the average modulus of elasticity on the basis of measured deformations, and the results were compared. Some of these methods utilized the measured midspan deflection, and others used the elastic curve obtained by digital image correlation.ResultsThe results showed that it was not appropriate to determine the average modulus of elasticity from only the measured midspan deflection. The consideration of deflections at multiple points along the beam axis is recommended.ConclusionsAn evaluation method based on the fitting of the analytically determined elastic curve of the beam with its nonuniform cross-sectional properties to the measured deflections is considered the most appropriate method for determining the average modulus of elasticity of the specimen.

Tentative indicators of malaria in archaeological skeletal samples, a pilot study testing different methods

ObjectiveThis study attempts to integrate multiple methods to investigate the presence of malaria in human skeletal samples from an archaeological context. Materials33 well preserved human remains originating from a 17th-century archaeological site in southeastern Romania. MethodsThe human bone samples were analyzed using rapid diagnostic tests for malaria antigens and PCR amplification of Plasmodium falciparum apical membrane antigen 1. A preliminary test was performed to identify and briefly characterize the presence of hemozoin using a combination of TEM imaging and diffraction. ResultsThe rapid diagnostic tests indicated that more than half of the examined samples were positive for Plasmodium antigens, but no traces of the parasites’ genetic material were detected despite repeated attempts. The TEM images indicated that hemozoin might be a promising diagnostic marker of malaria in ancient bones. ConclusionsThe indisputable identification of malaria in the analyzed archaeological population was not possible as none of the applied methodological strategies turned out to be straightforward. SignificanceThis study reinforces the intricacy and limitations of unequivocally identifying malaria in past populations and sets the stage for future studies on such life-threatening infectious disease in a geographical space, which is currently underrepresented in the bioarchaeological literature. LimitationsThe low sample size and the lack of consistency across all assays hindered understanding the role of malaria in the studied population. Suggestions for further researchFurther thorough multidisciplinary approaches on malaria detection in ancient settlements would be appropriate to inform our knowledge of its origins, frequency, and pathogen changes over centuries.

Reconstruction of diets based on the Δ15N values of individual amino acids at three sites in Sichuan, China

AbstractThis study analyzes the nitrogen isotope composition of individual amino acids in collagen extracted from human bone samples from the Gaoshan, Yingpanshan, and Xinyicun sites in Sichuan, where the isotope baseline is unavailable or incomparable with the isotopic data derived from human remains. It aims to understand the food compositions of the inhabitants at these sites, spanning the period from the late Neolithic to the middle Bronze Age, during which time agriculture and domestication of animals were introduced to the region and became increasingly important. The δ15N values of two amino acids, phenylalanine (δ15NPhe) and glutamic acid (δ15NGlu), indicate that the peoples on the Chengdu Plain mainly consumed terrestrial foods. The contribution of aquatic resources to their diet was limited. A possible explanation for the low dependence on aquatic foods is that the developed agriculture and domestication of animals offered sufficient foods. Such subsistence economies and dietary patterns were shaped in the early Baodun period (ca. 2,500–2000 BCE) at the latest and did not seem to change when transiting to the Bronze Age. This study also assesses the significance of these subsistence practices in supporting the social development of the Chengdu Plain.

Burned and buried: A vibrational spectroscopy analysis of burial-related diagenetic changes of heat-altered human bones.

The analysis of burned human remains can be very challenging due to heat-induced alterations. Occasionally, human bones present these coupled with diagenetic changes, offering even more of a challenge, since there is a lack of studies regarding interactions between both taphonomic phenomena. With this study, we aimed to assess and document the effects of inhumation on the chemical composition of both unburned and burned human skeletal remains. We buried, for 5 years, four groups of human bone samples comprising unburned bones and bones experimentally burned at 500, 900, and 1050 °C. Periodic exhumations were carried out to collect bone samples to be analyzed through Fourier transform infrared spectroscopy in attenuated total reflectance mode, in order to calculate four chemical indexes: (1) crystallinity index (CI); (2) type B carbonates to phosphate index (BPI); (3) total carbonates (A + B) to carbonate B ratio (C/C); and (4) OH to phosphate ratio (OH/P). After inhumation, CI and C/C of unburned bones and bones burned at 500 °C, and BPI of bones burned at 1050 °C did not vary significantly. However, the remaining indexes showed both relevant increments and reductions throughout observations, depending on burning temperature and index. Our results suggest that diagenesis can have an effect in bone's molecular composition. However, these effects do not seem to significantly affect the conclusions that can be taken from the analysis of infrared bone spectra, at least in the case of inhumations with a duration of 5 years or less.

Processing by Laser Stereolithography and &lt;i&gt;In Vitro&lt;/i&gt; Biological Evaluation of Hydroxyapatite Scaffolds Mimicking Human Trabecular Bone Architecture

Hydroxyapatite (HA) ceramic scaffolds are commonly used as bone graft substitutes. Design of such scaffolds is a challenge to improve biological properties and extend the applications of HA ceramics in the field of bone tissue engineering. In this work, we investigated the processing and the in vitro properties of HA ceramic scaffolds mimicking human trabecular bone architecture. Samples of human tibial trabecular bone were collected (University Hospital Center of Limoges) and scanned by X-Ray μ-computed tomography (μ-CT) to generate 3D model database. From this computer-aided design, HA ceramic scaffolds were shaped layer-by-layer by additive manufacturing using laser stereolithography (SLA). Then, green parts were sintered to obtain dense ceramic scaffolds. The shaped parts were compared to the model (wall thickness, size, and geometry of the porous network) using image analysis. A good agreement was found. Only small differences were detected due to a light overpolymerization or to some unprinted very small details that were not linked to a polymerized area of the previous layer. Due to part shrinkage during sintering a magnifying factor has to be applied to the scanned CAO model to match the real dimensions of the trabecular bone sample. Human mesenchymal stem cell (hMSC) cultures were performed to investigate the biological properties of these scaffolds (cell attachment and proliferation of hMSC). These preliminary biological evaluations show the good biocompatibility and cell adhesion of the HA substitute. This work evidences the efficiency of SLA to produce ceramic scaffold architectures mimicking that of the natural trabecular bone with promising biological behavior.

Comparison of deconvoluted-convoluted reconstituted ultrasound signals with their experimental original in a porous composite, cancellous bone

Langton previously suggested that the transmission of ultrasound through cancellous bone, a complex structured porous composite, may be considered as an array of parallel sonic-rays. The transit time of each sonic-ray is determined by the proportion of bone tissue and bone marrow, with minimum (tmin) and maximum (tmax) values corresponding to entire bone tissue and bone marrow, respectively. Moreover, a transit time spectrum (TTS) describes the proportion of sonic-rays as a function of transit time, P(ti), detected within the aperture of the receive transducer. The TTS effectively serves as the time-integrated impulse response (IR) of a test sample, and may be derived by deconvolution of experimentally derived output oe(t) and input ie(t) ultrasound signals. Conversely, a reconstituted output signal, or(t), may be obtained by convolution of oe(t) and the test sample's TTS. This study aimed to test these deconvolution and convolution relationships utilizing natural tissue cancellous bone samples. 1 MHz broadband experimental output transmission ultrasound signals, oe(t), through 16 natural tissue samples of human femoral cancellous bone samples were recorded. Corresponding reconstituted output signals, or(t), were derived through a two-stage deconvolution-convolution process. A linear regression fit yielded a high degree of agreement between experimental and reconstituted ultrasound output signals, with an average coefficient of determination (R2) of 0.96 ± 0.03. This study therefore provides further evidence for the reliability and validity of ultrasound transit time spectroscopy (UTTS) as an assessment technique that provides quantitative information on both the quantity and quality of cancellous bone.

Association between nanoscale strains and tissue level nanoindentation properties in age-related hip-fractures

Measurement of the properties of bone as a material can happen in various length scales in its hierarchical and composite structure. The aim of this study was to test the tissue level properties of clinically-relevant human bone samples which were collected from donors belonging to three groups: ageing donors who suffered no fractures (Control); untreated fracture patients (Fx-Untreated) and patient who experienced hip fracture despite being treated with bisphosphonates (Fx-BisTreated). Tissue level properties were assessed by (a) nanoindentation and (b) synchrotron tensile tests (STT) where strains were measured at the ‘tissue’, ‘fibril’ and ‘mineral’ levels by using simultaneous Wide-angle - (WAXD) and Small angle- X-ray diffraction (SAXD). The composition was analysed by thermogravimetric analysis and material level endo- and exo-thermic reactions by differential scanning calorimetry (TGA/DSC3+). Irrespective of treatment fracture donors exhibited significantly lower tissue, fibril and mineral strain at the micro and nanoscale respectively and had a higher mineral content than controls. In nanoindentation only nanohardness was significantly greater for Controls and Fx-BisTreated versus Fx-Untreated. The other nanoindentation parameters did not vary significantly across the three groups. There was a highly significant positive correlation (p < 0.001) between organic content and tissue level strain behaviour. Overall hip-fractures were associated with lower STT nanostrains and it was behaviour measured by STT which proved to be a more effective approach for predicting fracture risk because evidently it was able to demonstrate the mechanical deficit for the bone tissue of the donors who had experienced fractures.

Simulation study of the sensitivity of mechanical parameters on the reflected signal at the second interface of human cancellous bone—Application of Biot theory

A simulation study of mechanical parameters sensitivity to reflected ultrasound waves at the second interface of a hypothetical human cancellous bone sample is proposed. The sample is considered as a biphasic porous medium saturated by a fluid. The visco-inertial exchanges between the structure and the saturating fluid are described by the Biot theory modified by the Johnson model. An analytical expression of the reflection coefficient at the second interface is obtained in the frequency domain. This expression depends on three physical parameters, which are the porosity, the tortuosity, and the viscous characteristic length, as well as on mechanical parameters, Young's modulus and Poisson's ratio of the solid and the skeletal frame of the medium. The reflected signal is calculated in the frequency domain by the product of the spectrum of the incident signal by the reflection coefficient. In the time domain, the reflected wave is obtained by taking the inverse Fourier transform of the reflected frequency signal. The effect of mechanical parameters on the reflected signal inside the medium is studied. The results obtained are discussed and compared to those given in the literature.

Application of phase-field fracture theories and digital volume correlation to synchrotron X-ray monitored fractures in human trabecular bone: A case study

Fracture processes of trabecular bone have been studied using various approaches over the years. However, reliable methods to analyse fracture at the single trabecula level are limited. In this study, a digital volume correlation (DVC) and a phase-field fracture model are applied and contrasted for human trabecular bone to analyse its failure under global compression at high resolution.A human trabecular bone sample was fractured in situ under synchrotron-based X-ray micro computed tomography (CT). Reconstructed CT data was then used in DVC algorithms to obtain high-resolution displacement fields in the bone at different load steps. A high-resolution specimen-specific structural mesh was discretized from the CT data and used for the phase-field simulation of the fracturing bone.The DVC analysis showed opening mode cracks as well as shear mode cracks. Strains in cracked regions were analysed. The load distribution in the trabecular structure resulted in two completely separated fracture regions in the sample body. A phenomenon that was also captured in the phase-field model. The results encourage us to believe improvements in boundary conditions and material models are worthwhile pursuing. Findings in this study support further development of a phase-field method to analyse fracture in samples with complex morphology, such as trabecular bone, and the capacity of DVC to quantify strains and slowly growing stable fractures during step-wise loading of trabecular bone.

Stable isotopes reveal dietary shifts associated with social change in Hellenistic, Roman and Late Antique Knossos

Knossos was an important city on Crete and within Mediterranean networks in terms of trade and political status, though its status differed throughout the Hellenistic, Roman and Late Antique periods. This paper uses stable carbon and nitrogen isotope analysis to consider whether people at Knossos had differential diets due to the social, political, cultural, and economic changes across this time frame, factoring in age, sex and social status. Samples of human bone were selected to represent this range of time periods and variables.In this initial study, a small but insignificant increase in δ13C values was observed between the Hellenistic and Roman periods and there was a significant increase in δ15N values for the Late Antique period. No relationship between δ13C or δ15N and age was observed and while the female and male means were similar, the females had wider ranging values. No significant differences were detected by social status as represented by tomb type but there were small sample sizes for several of the tomb types.The results indicated a C3 terrestrial diet with meat or other animal products included for most individuals. The slight increase in δ13C values in the Roman period may represent either the introduction of a small amount of C4 plant or marine food, or very low trophic level marine foods into some Roman diets. The higher δ13C and, in particular, δ15N values observed in the Late Antique samples, suggests an increased consumption of seafood, potentially linked to Christian dietary practices or advances in fishing technologies and preservation techniques. The wider spread values of females compared to males, indicating a more varied diet, could have resulted from differential participation in religious institutions connected to food or may have been caused by greater nutritional stress in females in relation to pregnancy and reproductive issues.This study does not show a pattern of higher animal protein consumption in times of economic and cultural growth and prosperity but differences were detected between the different time periods in connection with the concurrent socio-economic changes.

Use of thermogravimetric analysis to estimate collagen and hydroxyapatite contents in archaeological bone

In this study, we evaluate whether thermogravimetric analysis (TGA) can be used to estimate the amounts of collagen and hydroxyapatite in archaeological bone accurately and rapidly, through evaluation of twenty-four previously analyzed archaeological human bone samples. Mass losses in the approximate ranges of 300–500 °C, 220–600 °C, and 600–900 °C, correspond to collagen mass loss, total organic mass loss, and hydroxyapatite mass loss, respectively. The first two mass losses (300–500 °C and 220–600 °C) show strong correlations with independently determined collagen content; however, the correlation between the third loss range (600–900 °C) and hydroxyapatite content was poor. Thus, TGA appears to be a good technique for estimating collagen but not apatite content in archaeological bone. As thermogravimetric analysis requires small amounts of material (tens of mg) and minimal sample preparation, while avoiding the superficiality of other collagen quantification methods (e.g., vibrational spectroscopy), it appears to be a promising technique for further archaeological exploration.

Post-Mortem Interval of Human Skeletal Remains Estimated with Handheld NIR Spectrometry.

Simple SummaryHandheld NIR spectrometry represents a non-destructive method to estimate post-mortem interval with a short sample-preparation time. Based on a deep-learning technique for post-mortem interval approach (ranging from 1 day up to 2000 years) an estimation of post-mortem interval with an accuracy of almost 100% in bones is possible.Estimating the post-mortem interval (PMI) of human skeletal remains is a critical issue of forensic analysis, with important limitations such as sample preparation and practicability. In this work, NIR spectroscopy (NIRONE® Sensor X; Spectral Engines, 61449, Germany) was applied to estimate the PMI of 104 human bone samples between 1 day and 2000 years. Reflectance data were repeatedly collected from eight independent spectrometers between 1950 and 1550 nm with a spectral resolution of 14 nm and a step size of 2 nm, each from the external and internal bone. An Artificial Neural Network was used to analyze the 66,560 distinct diagnostic spectra, and clearly distinguished between forensic and archaeological bone material: the classification accuracies for PMIs of 0–2 weeks, 2 weeks–6 months, 6 months–1 year, 1 year–10 years, and >100 years were 0.90, 0.94, 0.94, 0.93, and 1.00, respectively. PMI of archaeological bones could be determined with an accuracy of 100%, demonstrating the adequate predictive performance of the model. Applying a handheld NIR spectrometer to estimate the PMI of human skeletal remains is rapid and extends the repertoire of forensic analyses as a distinct, novel approach.

Raman microscopic spectroscopy as a diagnostic tool to detect Staphylococcus epidermidis in bone grafts

IntroductionRaman microscopic spectroscopyis a new approach for further characterization and detection of molecular features in many pathological processes. This technique has been successfully applied to scrutinize the spatial distribution of small molecules and proteins within biological systems by in situ analysis. This study uses Raman microscopic spectroscopyto identify any in-depth benefits and drawbacks in diagnosing Staphylococcus epidermidis in human bone grafts. Material and Methods40 non-infected human bone samples and 10 human bone samples infected with Staphylococcus epidermidis were analyzed using Raman microscopic spectroscopy. Reflectance data were collected between 200 cm−1 and 3600 cm−1 with a spectral resolution of 4 cm−1 using a Senterra II microscope (Bruker, Ettlingen, Germany). The acquired spectral information was used for spectral and unsupervised classification, such as principal component analysis. ResultsRaman measurements produced distinct diagnostic spectra that were used to distinguish between non-infected human bone samples and Staphylococcus epidermidis infected human bone samples by spectral and principal component analyses. A substantial loss in bone quality and protein conformation was detected by human bone samples co-cultured with Staphylococcus epidermidis. The mineral-to-matrix ratio using the phosphate/Amide I ratio (p = 0.030) and carbonate/phosphate ratio (p = 0.001) indicates that the loss of relative mineral content in bones upon bacterial infection is higher than in non-infected human bones. Also, an increase of alterations in the collagen network (p = 0.048) and a decrease in the structural organization and relative collagen in infected human bone could be detected. Subsequent principal component analyses identified Staphylococcus epidermidis in different spectral regions, respectively, originating mainly from CH2 deformation (wagging) of protein (at 1450 cm−1) and bending and stretching modes of C-H groups (∼2800-3000 cm−1). ConclusionRaman microscopic spectroscopyis presented as a promising diagnostic tool to detect Staphylococcus epidermidis in human bone grafts. Further studies in human tissues are warranted.

HUMAN DIET DURING THE STONE AGE AND EARLY METAL PERIOD (7000–1 CAL BC) IN LITHUANIA: AN UPDATE

ABSTRACTIn this study we present new carbon (δ13C) and nitrogen (δ15N) stable isotope data of human (n=13) and animal (n=40) bone and/or dentine collagen samples, alongside accelerator mass spectrometry radiocarbon (AMS 14C) dates of human remains (n=16). The studied material was sampled from Lithuanian sites dating from the Late Mesolithic to the pre-Roman Iron Age. For the first time, we present δ13C and δ15N data from Lithuanian freshwater fish as well as AMS 14C, δ13C, and δ15N measurements of human remains from six disturbed graves at the Donkalnis cemetery and from two pre-Roman Iron Age graves. According to the new results, human diet derived protein from the Late Mesolithic to Subneolithic (ca. 7000–2900 cal BC) was primarily based on freshwater fish. While previous macrobotanical and stable isotope studies has suggested that C4 plants, i.e., millet, became more widely used from the Late Bronze Age (1100–500 cal BC), our data suggests that millet consumption may have decreased during the pre-Roman Iron Age (500–1 cal BC) in the southeastern Baltic.