Trace-element analysis of human teeth and bone by proton-induced X-ray emission

The objective of our study is to correlate Fe, Cu, Zn, Pb, Br, Sr, and Mo concentrations in human teeth crown, root, and bone. The samples, teeth from a lower jaw bone and the lower jaw bone itself, were obtained from a 97-yr-old female cadaver. Two hundred milligrams of crown and root of the teeth, and lower jaw bones were fixed to a Kapton film and irradiated with a 3.8-MeV external proton beam from an 8-MV FN Tandem Van de Graaff Accelerator. TheF-test was used to analyze the difference between crown, root, and bone. It resulted in the following: For Fe, Zn, and Pb, the comparison showed significant differences among the three sample populations of tooth crown, root, and bone; for Cu, Br, Sr, and Mo, the comparison showed no significant differences among all three sample populations. Several elements in the samples were highly interrelated.     

Biological monitoring,by in vivo XRF measurements,of occupational exposure to lead,cadmium, and mercury

In vivo X-ray fluorescence (XRF) techniques were used for biological monitoring of lead, cadmium, and mercury. Lead accumulates in bone, the level of which may thus be used for monitoring of exposure. However, there was no close association between lead levels in bone and exposure time, partly because of differences in exposure patterns and partly, probably, because of variations in the toxicokinetics of lead. There are at least two separate bone lead compartments. The average over-all half-time is probably 5–10 yr. The finger bone level may be an index of the lead status of the total skeleton. In lead workers, the mobilization of bone lead causes an “internal” lead exposure and affects the blood lead level considerably. In cadmium workers, in vivo XRF is a sensitive and risk-free method for assessment of accumulation in kidney cortex, the critical tissue as to toxic effects; workers displayed increased levels. However, there was no clear association with duration and intensity of exposure, cadmium levels in urine, or microglobulinuria. Determinations of kidney cadmium may add important information on the state of accumulation and, thus, risk of kidney damage. Workers exposed to elemental mercury vapor, as well as fishermen exposed to methyl mercury, had mercury levels in bone below the detection limit of the XRF method.     

Processing of prehistoric bones for isotopic analysis and the meaning of collagen C/N ratios in the assessment of diagenetic effects

Diagenetic shifts in the isotopic composition of collagen in prehistoric bones still remain a big problem in the reconstruction of ancient diets by stable carbon and nitrogen isotope analysis. Recently,DeNiro (1985) suggested the measurement of bone collagen C/N ratios as a means of estimating substantial alterations of stable isotope ratios. Bones with collagen C/N ratios lying within a range between 2.9 and 3.6 should have isotopic properties quite close to thein vivo conditions. It can be demonstrated that the C/N ratios are varying considerably with the duration of acid hydrolyzation of the bone samples. Even small changes of the hydrolyzation time cause shifts in the C/N ratios large enought to produce values far outside the range worked out byDeNiro. Besides, our experiments led us to recommend a hydrolyzation at reducing conditions.     

Quantitation of hydroxypyridinium crosslinks in collagen by high-performance liquid chromatography

An HPLC method for quantifying the 3-hydroxypyridinium crosslinks of collagen is described. It can be applied to crude hydrolysates of all types of connective tissue. Mineralized tissues can be hydrolyzed directly and analyzed without interference from the mineral ions. The hydroxylysyl (HP) and lysyl (LP) forms of hydroxypyridinium residue were resolved on a reverse-phase C18 column using a gradient of acetonitrile in water and 0.01 M n-heptafluorobutyric acid as an ion-pairing agent. The crosslinking amino acids were accurately quantified down to 2 PM (1 ng) injected, by detecting their natural fluorescence with a spectrofluorometer. Tissues in which hydroxypyridinium crosslinks were plentiful included all forms of cartilage, bone, dentin, ligament, tendon, fascia, intervertebral disc, lung, gut, cervix, aorta, and vitreous humor. Among normal tissues, LP, the minor form of the crosslink, was present in significant amounts relative to HP only in bone and dentin. Both crosslinks were essentially absent from skin, cornea, rat tail tendon, and basement membranes.     

The effect of extracellular calcium elevation on morphology and function of isolated rat osteoclasts

Osteoclasts are large multinucleate cells unique in their capacity to resorb bone. These cells are exposed locally to high levels of ionised calcium during the process of resorption. We have therefore examined the effect of elevated extracellular calcium on the morphology and function of freshly disaggregated rat osteoclasts. Cell size and motility were quantitated by time-lapse video recording together with digitisation and computer-centred image analysis. In order to assess the resorptive capacity of isolated osteoclasts, we measured the total area of resorption of devitalised cortical bone by means of scanning electron microscopy and computer-based morphometry. The results show that elevation of the extracellular calcium concentration causes a dramatic reduction of cell size, accompanied by a marked diminution of enzyme release and abolition of bone resorption. We propose that ionised calcium might play an important role in the local regulation of osteoclastic bone resorption.     

Cranial function in a late Miocene Dinocrocuta gigantea (Mammalia: Carnivora) revealed by comparative finite element analysis

Carnivoran ecomorphologies evolved repeatedly during the Cenozoic. Whereas extreme forms (e.g. sabretoothed predators) probably represent similarities in ecology, other morphologies are more subtle with respect to the extent of their shared niche space. Finite element models of the skulls of Dinocrocuta gigantea , Canis lupus , and Crocuta crocuta were constructed to test the interpretation of D. gigantea as a bone cracker, an interpretation made on the basis of its large, conical premolars, and robust cranial morphology. Dinocrocuta gigantea is also of interest because it represents a lineage that has been placed in its own family, sister to Hyaenidae. Thus, functional similarity in craniodental performance could represent rapid convergence. The findings obtained indicate that the crania of D. gigantea and C. crocuta perform better in stress dissipation and distribution than that of C. lupus , regardless of P3 or P4 biting. In particular, the domed frontal region of the bone crackers received lower and more evenly distributed stress than C. lupus . Thus, the craniodental forms of the two bone-crackers are linked by functional advantage over that of C. lupus . Further examination of lineages such as borophagine canids could elucidate the extent of functional convergence of the bone-cracking ecomorph across diverse groups.  © 2009 The Linnean Society of London, Biological Journal of the Linnean Society , 2009, 96 , 51–67.     

Stable isotopic evidence for diet at the Imperial Roman coastal site of Velia (1st and 2nd Centuries AD) in Southern Italy

Here we report on a stable isotope palaeodietary study of a Imperial Roman population interred near the port of Velia in Southern Italy during the 1st and 2nd centuries AD. Carbon and nitrogen stable isotope analyses were performed on collagen extracted from 117 adult humans as well as a range of fauna to reconstruct individual dietary histories. For the majority of individuals, we found that stable isotope data were consistent with a diet high in cereals, with relatively modest contributions of meat and only minor contributions of marine fish. However, substantial isotopic variation was found within the population, indicating that diets were not uniform. We suggest that a number of individuals, mainly but not exclusively males, had greater access to marine resources, especially high trophic level fish. However, the observed dietary variation did not correlate with burial type, number of grave goods, nor age at death. Also, individuals buried at the necropolis at Velia ate much less fish overall compared with the contemporaneous population from the necropolis of Portus at Isola Sacra, located on the coast close to Rome. Marine and riverine transport and commerce dominated the economy of Portus, and its people were in a position to supplement their own stocks of fish with imported goods in transit to Rome, whereas at Velia marine exploitation existed side‐by‐side with land‐based economic activities. Am J Phys Anthropol, 2009. © 2009 Wiley‐Liss, Inc.     

Mechanobiology of embryonic skeletal development: Insights from animal models

A range of clinical conditions in which fetal movement is reduced or prevented can have a severe effect on skeletal development. Animal models have been instrumental to our understanding of the interplay between mechanical forces and skeletal development, particularly the mouse and the chick model systems. In the chick, the most commonly used means of altering the mechanical environment is by pharmaceutical agents which induce paralysis, whereas genetically modified mice with nonfunctional or absent skeletal muscle offer a valuable tool for examining the interplay between muscle forces and skeletogenesis in mammals. This article reviews the body of research on animal models of bone or joint formation in vivo in the presence of an altered or abnormal mechanical environment. In both immobilized chicks and “muscleless limb” mice, a range of effects are seen, such as shorter rudiments with less bone formation, changes in rudiment and joint shape, and abnormal joint cavitation. However, although all bones and synovial joints are affected in immobilized chicks, some rudiments and joints are unaffected in muscleless mice. We propose that extrinsic mechanical forces from movements of the mother or littermates impact on skeletogenesis in mammals, whereas the chick embryo is reliant on intrinsic movement for mechanical stimulation. The insights gained from animal models into the mechanobiology of embryonic skeletal development could provide valuable cues to prospective tissue engineers of cartilage and bone and contribute to new or improved treatments to minimize the impact on skeletal development of reduced movement in utero. Birth Defects Research (Part C) 90:203–213, 2010. © 2010 Wiley‐Liss, Inc.     

A fossil hominid frontal from Velika Pećina (Croatia) and a consideration of Upper Pleistocene hominids from Yugoslavia

Fossil hominid remains dating to the Upper Pleistocene in Yugoslavia are reviewed. Particular emphasis is placed on the assessment of a hominid frontal from the site of Velika Pe?ina in northwestern Croatia. This specimen represents the earliest absolutely-dated hominid associated with the Upper Paleolithic in Europe. Also the hominid material from the site of Veternica is discussed, and data are presented on the new remains from ?andalja. It is concluded that no Neandertal remains, except for Krapina, have been found in Yugoslavia.     

The IGF‐I regulatory system and its impact on skeletal and energy homeostasis

Insulin‐like growth factor (IGF)‐I is important in the acquisition and maintenance of both soft and hard tissues. Skeletal remodeling requires energy and recent work has demonstrated that bone can influence insulin sensitivity and thereby regulate metabolic processes. New insights from mouse models into the role of IGF‐binding proteins (IGFBPs) as more than mere depots for the IGFs has reignited investigations into the metabolic targets influenced by the IGF regulatory system and the pathways that link bone to adipose tissue. Although there remains continued uncertainty about the relative balance between the effects of circulating versus tissue IGF‐I actions, the role of the IGFBPs has been redefined both as modulators of IGF‐I action and as independent signaling factors. This review highlights several recent findings that shed new light on the physiologic role of the IGF regulatory system and its influence on skeletal and fat metabolism. J. Cell. Biochem. 111: 14–19, 2010. © 2010 Wiley‐Liss, Inc.