Collagen

Biodegradable polymer scaffolds have played a
significant role in wide range of tissue engineering application
such as bone scaffolds since the last decade. The aim
of this article is to provide the comprehensive overview of
biocompatible and biodegradable polymer materials and
composite materials with their advantages and drawbacks
in the application of biomaterial scaffolds, furthermore the
properties and degradation criteria of the biomaterials are
discussed in this review.

Studies in athletes have shown that carnitine supplementation may foster exercise performance. As reported in the majority of studies, an increase in maximal oxygen consumption and a lowering of the respiratory quotient indicate that dietary carnitine has the potential to stimulate lipid metabolism. Treatment with L-carnitine also has been shown to induce a significant postexercise decrease in plasma lactate, which is formed and used continuously under fully aerobic conditions. Data from preliminary studies have indicated that L-carnitine supplementation can attenuate the deleterious effects of hypoxic training and speed up recovery from exercise stress. Recent data have indicated that L-carnitine plays a decisive role in the prevention of cellular damage and favorably affects recovery from exercise stress. Uptake of L-carnitine by blood cells may induce at least three mechanisms: 1) stimulation of hematopoiesis, 2) a dose-dependent inhibition of collagen-induced platelet aggregatio...

Mosti, MP, Kaehler, N, Stunes, AK, Hoff, J, and Syversen, U. Maximal strength training in postmenopausal women with osteoporosis or osteopenia. J Strength Cond Res 27(10): 2879-2886, 2013-Current guidelines recommend weightbearing activities, preferably strength training for improving skeletal health in patients with osteoporosis. What type of strength training that is most beneficial for these patients is not established. Maximal strength training (MST) is known to improve 1-repetition maximum (1RM) and rate of force development (RFD), which are considered as important covariables for skeletal health. Squat exercise MST might serve as an effective intervention for patients with low bone mass. We hypothesized that 12 weeks of squat exercise MST would improve 1RM and RFD in postmenopausal women with osteoporosis or osteopenia and that these changes would coincide with improved bone mineral density (BMD) and bone mineral content (BMC), and serum markers of bone metabolism. The participants were randomized to a training group (TG, n = 10) or control group (CG, n = 11). The TG underwent 12 weeks of supervised squat exercise MST, 3 times a week, with emphasis on rapid initiation of the concentric part of the movement. The CG was encouraged to follow current exercise guidelines. Measurements included 1RM, RFD, BMD, BMC, and serum bone metabolism markers; type 1 collagen amino-terminal propeptide (P1NP) and type 1 collagen C breakdown products (CTX). At posttest, 8 participants remained in each group for statistical analyses. The TG improved the 1RM and RFD by 154 and 52%, respectively. Lumbar spine and femoral neck BMC increased by 2.9 and 4.9%. The ratio of serum P1NP/CTX tended to increase (p = 0.09), indicating stimulation of bone formation. In conclusion, squat exercise MST improved 1RM, RFD, and skeletal properties in postmenopausal women with osteopenia or osteoporosis. The MST can be implemented as a simple and effective training method for patients with reduced bone mass.

The present paper intends to overview a wide range of natural-origin polymers with special focus on proteins and polysaccharides (the systems more inspired on the extracellular matrix) that are being used in research, or might be potentially useful as carriers systems for active biomolecules or as cell carriers with application in the tissue engineering field targeting several biological tissues. The combination of both applications into a single material has proven to be very challenging though. The paper presents also some examples of commercially available natural-origin polymers with applications in research or in clinical use in several applications. As it is recognized, this class of polymers is being widely used due to their similarities with the extracellular matrix, high chemical versatility, typically good biological performance and inherent cellular interaction and, also very significant, the cell or enzyme-controlled degradability. These biocharacteristics classify the natural-origin polymers as one of the most attractive options to be used in the tissue engineering field and drug delivery applications.

Chemotaxis, directed cell migration in a gradient of chemoattractant, is an important biological phenomenon that plays pivotal roles in cancer metastasis. Newly developed microfluidic chemotaxis chambers (MCC) were used to study chemotaxis of metastatic breast cancer cells, MDA-MB-231, in EGF gradients of well-defined profiles. Migration behaviors of MDA-MB-231 cells in uniform concentrations of EGF (0, 25, 50, and 100 ng/ml) and EGF (0-25, 0-50, and 0-100 ng/ml) with linear and nonlinear polynomial profiles were investigated. MDA-MB-231 cells exhibited increased speed and directionality upon stimulation with uniform concentrations of EGF. The cells were viable and motile for over 24 h, confirming the compatibility of MCC with cancer cells. Linear concentration gradients of different ranges were not effective in inducing chemotactic movement as compared to nonlinear gradients. MDA-MB-231 cells migrating in EGF gradient of 0-50 ng/ ml nonlinear polynomial profile exhibited marked directional movement toward higher EGF concentration. This result suggests that MDA-MB-231 cancer cell chemotaxis depends on the shape of gradient profile as well as on the range of EGF concentrations. D 2004 Elsevier Inc. All rights reserved.

There is increasing evidence that cells of the epithelial root sheath synthesize enamal matrix proteins and that these proteins play a fundamental rô le in the formation of acellular cementum, the key tissue in the development of a functional periodontium. The purpose of the present study was to explore the effect of locally applied enamel matrix and different protein fractions of the matrix on periodontal regeneration in a buccal dehiscence model in monkeys. Buccal, mucoperiosteal flaps were raised from the canine to the 1st molar on each side of the maxilla. The buccal alveolar bone plate, the exposed periodontal ligament and cementum were removed. Various preparations of porcine enamel matrix with or without vehicles were applied before the flaps were repositioned and sutured. After 8 weeks, the healing was evaluated in the light microscope, and morphometric comparisons were made. Application of homogenized enamel matrix or an acidic extract of the matrix containing the hydrophobic, low molecular weight proteins, amelogenins, resulted in an almost complete regeneration of acellular cementum, firmly attached to the dentin and with collagenous fibers extending over to newly formed alveolar bone. After application of fractions obtained by neutral EDTA extraction containing the acidic, high molecular weight proteins of the enamel matrix, very little new cementum was formed and hardly any new bone. The results of the controls in which no test substance was applied before the repositioning of the flap, were very similar to those obtained with the EDTA extracted material. Propylene glycol alginate (PGA), hydroxyethyl cellu-

background. The periorbital region serves as a barometer of chronologic and environmental age and, as such, patients often seek its cosmetic rejuvenation. objective. The purpose of this article was to review the dermatologic treatments available for periorbital skin rejuvenation. methods. Topical retinoic and glycolic acid preparations, chemical peels, botulinum and collagen injections, dermabrasion, and laser resurfacing procedures for periorbital skin rejuvenation were reviewed. The relative benefits and risks of each treatment were detailed.

A preparative protein alkaline hydrolysis procedure, as part of a spectrophotometric collagen quantification method, is presented. The procedure is suitable for small amounts of fresh solid or liquid samples. Various aspects of the procedure, such as the NaOH concentration, time needed to hydrolyse different collagen contents, buffer strength of the reagent solution, pH control of the hydrolysate and spectrophotometric conditions, were evaluated. Compared to other procedures that use alkaline hydrolysis, the sensitivity of this procedure was increased by a factor of 5. Compared to the conventionally used Association of Official Analytical Chemists (AOAC) acid hydrolysis method, the reaction time was reduced from 16 h to 40 min and the amount of sample from 4 g to 3-20 mg, producing equivalent results when applied to porcine liver and sausage samples.

Carbon stable isotope ratios (δ13C), measured in human bone collagen (δ13Ccollagen) and bioapatite (δ13Cbioapatite), are commonly used indicators in ancient human diet reconstruction. The underlying assumption is that human tissues broadly reflect the δ13C signal of dietary food sources (δ13Cdiet) plus an isotopic offset. However, interpretation of results may be confounded by the differentiated routing of macronutrients (energy, that is carbohydrates and lipids, and protein) having associated different isotopic signals (δ13Cenergy, δ13Cprotein). Multiple regression analyses were conducted on data from controlled animal feeding experiments compiled by Froehle et al. (J Archaeol Sci 37:2662–2670, 2010). We derived a simple algebraic macronutrient-based model with δ13Cbioapatite = 10.1 + δ13Cdiet (‰) and δ13Ccollagen = 4.8 + 0.74 δ13Cprotein + 0.26 δ13Cenergy (‰). While the established relationship for δ13Cbioapatite is similar to previously known results, the model also suggests that δ13Ccollagen signal contributions originate from surprisingly consistent proportions of protein and energy macronutrients. Given that feeding experiments explore extreme variations in the proportion of diet macronutrients, the applicability of the proposed model and its predictions were tested in a variety of well-known, wild animal and human, natural contexts. Possible biochemical mechanisms explaining these empirical results are discussed.

Tephrosia purpurea is a well-known herb for its hepatoprotective, anticancer, antiulcer, antibacterial and in healing bleeding piles, etc. The present study was aimed for wound healing potential of ethanolic extract of Tephrosia purpurea (aerial part) in the form of simple ointment using three types of wound models in rats as incision wound, excision wound and dead space wound. The results were comparable to standard drug Fluticasone propionate ointment, in terms of wound contraction, tensile strength, histopathological and biochemical parameters such as hydroxyproline content, protein level, etc. Histopathological study showed significant (P < 0.05) increase in fibroblast cells, collagen fibres and blood vessels formation. All parameters were observed significant (P < 0.05) in comparison to control group.

The compositions and some properties of acid-soluble collagens (ASC) of the skin and bone of bigeye snapper, (Priacanthus tayenus) were investigated. The collagens were extracted with the yields of 10.94% and 1.59% on the basis of wet weight, from skin and bone, respectively. Similar electrophoretic patterns of collagens from the skin and bone were observed. Both collagens comprised two different ? chains, ?1 and ?2 and were classified as type I collagen. However, peptide maps of collagen from the skin and bone of bigeye snapper, digested by V8 protease and lysyl endopeptidase, revealed differences between collagens from skin and bone, and both were completely different from those of calf skin collagen. Collagen rehydrated in acetic acid had lower T max and enthalpy than those rehydrated in deionised water, suggesting a conformational change caused by acid. Collagens form the skin and bone had the highest solubility at pH 2 and 5, respectively. No changes in solubility were observed in the presence of NaCl up to 3% (w/v). However, a sharp decrease in solubility was found with NaCl above 3% (w/v).

Hoy en día, el campo de la investigación arqueológica recibe cada vez más la inestimable ayuda de la tecnología, pudiendo realizar tareas que hace años le serían impensables, como observar algo con miles de aumentos, saber de qué se alimentaban en el pasado o relacionar genéticamente poblaciones de diferente espacio o tiempo. Sin embargo, es necesario saber cómo hacer uso adecuadamente de esta tecnología, para interpretar el pasado de la manera más acertada posible. En este trabajo se desarrolla una síntesis de las principales técnicas en investigación arqueológica, centrando la atención en el estudio de los restos óseos e ilustrando cada técnica con ejemplos que puedan ayudar a su comprensión.
Palabras clave: huesos humanos, colágeno, ADN, PCR, isótopos, paleodietas, ICP-MS, FRX, SEM

Nowadays, the field of archaeological research receives increasingly the priceless help of the technology, being able to solve tasks in a manner which would seem unthinkable years ago, as watching something thousands of times zoomed in, knowing what did the people from the past eat or relate genetically populations coming from different ages or locations. However, knowledge of the correct use of this technology is needed, in order to read the past in the most accurate way. On this paper, a synthesis of the main techniques for archaeological research is developed, focusing the attention on the study of skeletal remains and giving examples for the application of each technique to provide its understanding.
Keywords: human bones, collagen, DNA, PCR, isotopes, paleodiets, ICP-MS, XRF, SEM

Species identification of fragmentary bone, such as in rendered meat and bone meal or from archaeological sites, is often difficult in the absence of clear morphological markers. Here we present a robust method of analysing genus-specific collagen peptides by mass spectrometry simply by using solid-phase extraction (a C18 ZipTip 1 ) for peptide purification, rather than liquid chromatography/ mass spectrometry (LC/MS). Analysis of the collagen from 32 different mammal species identified a total of 92 peptide markers that could be used for species identification, for example, in processed food and animal feed. A set of ancient (>100 ka@10-C) bone samples was also analysed to show that the proposed method has applications to archaeological bone identification. Figure 3. MS/MS spectra showing the de novo sequencing interpretation of a known rabbit collagen peptide at m/z 2957 (COL1A2T62) and the identification of the analogous camel peptide at m/z 2991.

The skin is pulled taught to stabilize the defect and multiple boluses of filler are delivered along the defect line. The injection sites should be close enough to form a continuous smooth bead; however, small gaps can be moulded with massage. This technique is useful for acne scarring, shallow forehead rhytids, the glabella, philtrum enhancement and nonsurgical rhinoplasty.

Microtubules, actin, and collagen are macromolecular structures that compose a large percentage of the proteins in the human body, helping form and maintain both intracellular and extracellular structure. They are biological wires and are structurally connected through various other proteins. Microtubules (MTs) have been theorized to be involved in classical and quantum information processing, and evidence continues to suggest possible semiconduction through MTs. The previous Dendritic Cytoskeleton Information Processing Model has hypothesized how MTs and actin form a communication network in neurons. Here, we review information transfer possibilities involving MTs, actin, and collagen, and the evidence of an organism-wide high-speed communication network that may regulate morphogenesis and cellular proliferation. The direct and indirect evidence in support of this hypothesis, and implications for chronic diseases such as cancer and neurodegenerative diseases are discussed.

The sensitivity of magnetic resonance imaging to biochemical and biophysical changes in the extracellular matrix of articular cartilage give it the potential to noninvasively detect the earliest changes of cartilage damage. The transverse relaxation time (T2) of cartilage has been shown to be a sensitive parameter for evaluation of early degeneration in articular cartilage, particularly changes in water and collagen content and tissue anisotropy. Although initial application has been in microimaging of small cartilage explants, in vivo techniques have been developed for cartilage T2 mapping of human joints. In addition to potential application in development of new pharmaceuticals and surgical techniques for preserving cartilage, in vivo cartilage T2 mapping can improve understanding of arthritis, cartilage aging, and response of cartilage to exercise.

The tools of recombinant protein expression are now being used to provide recombinant sources of both collagen and gelatin. The primary focus of this review is to discuss alternatives to bovine collagen for biomedical applications. Several recombinant systems have been developed for production of human sequence collagens. Mammalian and insect cells were initially used, but were thought to be too costly for commercial production. Yeast have been engineered to express high levels of type I homotrimer and heterotrimer and type II and type III collagen. Co-expression of collagen genes and cDNAs encoding the subunits of prolyl hydroxylase has lead to the synthesis of completely hydroxylated, thermostable collagens. Human types I and III collagen homotrimers have been expressed in transgenic tobacco plants, while transgenic mice have been engineered to produce full-length type I procollagen homotrimer as well as a α2 (I) homotrimeric mini-collagen. Most recently, a transgenic silkworm system was used to produce a fusion protein containing a collagenous sequence. Each of these transgenic systems holds great promise for the cost-effective large-scale production of recombinant human collagens. As seen in other recombinant expression systems, transgenic silkworms, tobacco, and mice lack sufficient endogenous prolyl hydroxylase activity to produce fully hydroxylated collagen. In mice and tobacco, this was overcome by over-expression of prolyl hydroxylase, analogous to what has been done in yeast and insect cell culture. In addition to recombinant alternatives to bovine collagen, other sources such as fish and sponge collagen are discussed briefly. Recombinant gelatin has been expressed in Pichia pastoris and Hansenula polymorpha in both non-hydroxylated and hydroxylated forms. Pichia was shown to be a highly productive system for gelatin production. The recombinant gelatins produced in yeast are of defined molecular weight and physio-chemical properties and represent a new biomaterial not previously available from animal sources. Genetic engineering has made great progress in the areas of recombinant collagen and gelatin expression, and there are now several alternatives to bovine material that offer an enhanced safety profile, greater reproducibility and quality, and the ability of these materials to be tailored to enhance product performance.

Labisia pumila is a traditional herb widely used as post-partum medication for centuries. Recently, extensive researches have been carried out on the phytochemical identification, biological and toxicological studies for the herb. Phytochemicals found in the herbal extract showed high antioxidant properties, which were essential for various pharmacological activities. The significant findings are anti-estrogenic deficiency and -immunodeficiency diseases. Another finding that has considerable impact on natural product research is the contribution of L. pumila in promoting skin collagen synthesis. The performance of the herb as anti-aging agent due to natural aging process and accelerated by UV radiation was reviewed critically.

ABSTRACT
Juan Luí­s Martí­nez, poeta que a fines de los 70' y principios de los 80' irrumpió en la escena lí­rica chilena con una poesí­a rupturista, escéptica e iconoclasta, incomprendida por buena parte de la crí­tica y rechazada por más de un editor. Los versos de Martí­nez han circulado por más de 20 años en fotocopias, aunque ahora la situación empieza a cambiar. La Nueva Novela obra paradigmática de la vanguardia poética chilena se ha convertido en un objeto de un nuevo culto, el de la tacha de la autorí­a y la disolución del autor.
El poeta Juan Luis Martí­nez se ha transformado en icono de nuestra vanguardia literaria, aun cuando, según su propio designio, irradia una identidad velada, fantasmal, "más literaria que real", en algún momento se creyó que el era una invención de Enrique Lihn, que escribió una de las más lúcidas reseñas de este poeta legendario: "Señales de Ruta de Juan Luis Martí­nez"1. Una suerte de icono bizarro dentro de nuestro panorama literario. Tanto por la complejidad de su obra como por el desconocimiento puntual de lo que ésta significa. No han sido pocas las aproximaciones que se han realizado en torno a la producción literaria del poeta ˆ’la cual comprende sólo tres obras: La Nueva Novela (1977), La Poesí­a Chilena (1978) y Poemas del Otro (2003)ˆ’ a lo largo de los años, llamando la atención la multiplicidad de enfoques con que se le ha abordado.
La noción de "autor" –como creador individual de una obra artí­stica o literaria– se puede situar histórica y culturalmente en el tránsito de la modernidad a la posmodernidad, la noción de creador individual empieza a problematizarse desde fines del siglo XIX y a lo largo del siglo XX, donde la noción se hace insostenible.

Ancient Maya diet at Caledonia, Cayo District, Belize (Late Preclassic to Terminal Classic periods), was investigated using stable carbon and nitrogen isotope analysis of human bone collagen, bioapatite and tooth enamel bioapatite. These data were compared to skeletal and dental evidence of diet and nutritional stress, and dietary differences based on age, sex, social status and time period were considered. The diet of the Caledonia Maya was based on maize, supplemented with maize-fed terrestrial animal protein and freshwater mollusc protein. Due to small sample sizes, no relationships between diet and pathology, age, sex, social status or time period were discerned. The Caledonia Maya did consume diets similar to those at neighbouring sites, as well as to sites in the Petén of Guatemala. This study demonstrates that although small sample sizes can preclude the detection of intra-site trends at minor centres such as Caledonia, intersite comparisons can provide information on regional dietary practices.

Acid soluble collagen (ASC) and pepsin soluble collagen (PSC) from the skin of brownbanded bamboo shark (Chiloscyllium punctatum) were isolated and characterised. The yield of ASC and PSC were 9.38% and 8.86% (wet weight basis), respectively. Based on protein patterns and TOYOPEARLฎ CM-650M column chromatography, both collagens contained [alpha]- and [beta]-chains as their major components. These were characterised as type I collagen with the cross-link of [alpha]2-chain. As digested by V8-protease and lysyl endopeptidase, peptide maps of both ASC and PSC were similar, but differed from that of type I collagen from calf skin. Fourier transform infrared (FTIR) spectra of both collagens were similar and pepsin hydrolysis had no effect on triple-helical structure of collagen. Transition temperature (Tmax) of ASC and PSC were 34.45 and 34.52 ฐC, respectively, as determined by differential scanning colorimetry (DSC). From zeta potential study, the isoelectric points of ASC and PSC were estimated to be 6.21 and 6.56, respectively. Therefore, the skin of brownbanded bamboo shark could serve as an alternative source of collagen for different applications.

Bone fragility is a major health concern, as the increased risk of bone fractures has devastating outcomes in terms of mortality, decreased autonomy, and healthcare costs. Efforts made to address this problem have considerably increased our knowledge about the mechanisms that regulate bone formation and resorption. In particular, we now have a much better understanding of the cellular events that are triggered when bones are mechanically stimulated and how these events can lead to improvements in bone mass. Despite these findings at the molecular level, most exercise intervention studies reveal either no effects or only minor benefits of exercise programs in improving bone mineral density (BMD) in osteoporotic patients. Nevertheless, and despite that BMD is the gold standard for diagnosing osteoporosis, this measure is only able to provide insights regarding the quantity of bone tissue. In this article, we review the complex structure of bone tissue and highlight the concept that its mechanical strength stems from the interaction of several different features. We revisited the available data showing that bone mineralization degree, hydroxyapatite crystal size and heterogeneity, collagen properties, osteocyte density, trabecular and cortical microarchitecture, as well as whole bone geometry, are determinants of bone strength and that each one of these properties may independently contribute to the increased or decreased risk of fracture, even without meaningful changes in aBMD. Based on these findings, we emphasize that while osteoporosis (almost) always causes bone fragility, bone fragility is not always caused just by osteoporosis, as other important variables also play a major role in this etiology. Furthermore, the results of several studies showing compelling data that physical exercise has the potential to improve bone quality and to decrease fracture risk by influencing each one of these determinants are also reviewed. These findings have meaningful clinical repercussions as they emphasize the fact that, even without leading to improvements in BMD, exercise interventions in patients with osteoporosis may be beneficial by improving other determinants of bone strength.

Microneedles are a modestly invasive technique that gained mass popularity, and is utilized to break the top skin layer into tiny holes which self regenerate and rejuvenate the skin and facilitate the delivery of certain nutrients, proteins, drugs, antiageing, products and vitamins on the skin surface and underneath in the form of mesotherapy, being a form of controlled intradermal (transdermal drug absorption) applications. It has been an extensively researched topic in the
field of cosmetology and aesthetic dermatology and has grabbed great attention all over the world. It stimulates elastin and collagen production through a controlled cascade of inflammation initiation, and then followed by production and remodeling of collagen and elastin the skin
dermis. Eventually it helps in thickening of the skin, improving its texture and appearance and by combating skin aging process.

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 y

Background: Skin laxity, rhytides, and photoaging are generally treated by ablative procedures that injure or destroy the epidermis and its basement membrane, at least in the beginning, and subsequently lead to fibrosis of the papillary dermis. The ideal treatment would be to preserve the epidermis and promote normal collagen and elastin formation in the dermis. Percutaneous collagen induction takes us

Tissue engineering is an interdisciplinary field that has attempted to utilize a variety of processing methods with synthetic and natural polymers to fabricate scaffolds for the regeneration of tissues and organs. The study of structure-function relationships in both normal and pathological tissues has been coupled with the development of biologically active substitutes or engineered materials. The fibrillar collagens, types I, II, and III, are the most abundant natural polymers in the body and are found throughout the interstitial spaces where they function to impart overall structural integrity and strength to tissues. The collagen structures, referred to as extracellular matrix (ECM), provide the cells with the appropriate biological environment for embryologic development, organogenesis, cell growth, and wound repair. In the native tissues, the structural ECM proteins range in diameter from 50 to 500 nm. In order to create scaffolds or ECM analogues, which are truly biomimicking at this scale, one must employ nanotechnology. Recent advances in nanotechnology have led to a variety of approaches for the development of engineered ECM analogues. To date, three processing techniques (selfassembly, phase separation, and electrospinning) have evolved to allow the fabrication of nanofibrous scaffolds. With these advances, the long-awaited and much anticipated construction of a truly "biomimicking" or "ideal" tissue engineered environment, or scaffold, for a variety of tissues is now highly feasible. This review will discuss the three primary technologies (with a focus on electrospinning) available to create tissue engineering scaffolds that are capable of mimicking native tissue, as well as explore the wide array of materials investigated for use in scaffolds.

cartilage when implanted in vivo . A culture sys-A culture system that facilitates the chondrogenic tem has been developed in which these cells will undifferentiation of rabbit bone marrow-derived mesen-dergo osteogenic differentiation in vitro . However, chymal progenitor cells has been developed. Cells obattempts to develop in vitro conditions in which mesentained in bone marrow aspirates were first isolated by chymal progenitor cells isolated from postnatal mammonolayer culture and then transferred into tubes and malian bone marrow will progress down the chondroallowed to form three-dimensional aggregates in a genic lineage have been less successful. There are studchemically defined medium. The inclusion of 10 07 M ies reporting in vitro chondrogenesis using postnatal dexamethasone in the medium induced chondrogenic mammalian cells , but none have demonstrated differentiation of cells within the aggregate as evihistologically identifiable cartilage formation, although denced by the appearance of toluidine blue metachrotype II collagen production has been detected, sugmasia and the immunohistochemical detection of type gesting at least prechondroid tissue production.

The relationship of cell proliferation to the temporal expression of genes characterizing a developmental sequence associated with bone cell differentiation was examined in primary diploid cultures of fetal calvarial derived osteoblasts by the combined use of autoradiography, ...

The Middle to Upper Palaeolithic transition around 35,000 years ago coincides with the replacement of Neanderthals by anatomically modern humans in Europe. Several hypotheses have been suggested to explain this replacement, one of them being the ability of anatomically modern humans to broaden their dietary spectrum beyond the large ungulate prey that Neanderthals consumed exclusively. This scenario is notably based on higher nitrogen-15 amounts in early Upper Palaeolithic anatomically modern human bone collagen compared with late Neanderthals. In this paper, we document a clear increase of nitrogen-15 in bone collagen of terrestrial herbivores during the early Aurignacian associated with anatomically modern humans compared with the stratigraphically older Châtelperronian and late Mousterian fauna associated with Neanderthals. Carnivores such as wolves also exhibit a significant increase in nitrogen-15, which is similar to that documented for early anatomically modern humans compared with Neanderthals in Europe. A shift in nitrogen-15 at the base of the terrestrial foodweb is responsible for such a pattern, with a preserved foodweb structure before and after the Middle to Upper Palaeolithic transition in south-western France. Such an isotopic shift in the terrestrial ecosystem may be due to an increase in aridity during the time of deposition of the early Aurignacian layers. If it occurred across Europe, such a shift in nitrogen-15 in terrestrial foodwebs would be enough to explain the observed isotopic trend between late Neanderthals and early anatomically modern humans, without any significant change in the diet composition at the Middle to Upper Palaeolithic transition