SEARCH · PubMed Health

Results for “Skeleton”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 487 records · Page 27Linked to original sources

PubMed1981

Biocompatibility of echinoderm skeleton with mammalian cells in vitro: preliminary evidence.

The physical and chemical properties of echinoderm skeleton are reviewed. A method is described for preparing cell-free, sterile echinoderm skeletal plates (ossicles) which were used as porous substrates for cell cultures. Ossicles of the starfish Pisaster ochraceus were evaluated as substrates for the culture of three mammalian cell lines. Each line grew vigorously on ossicles, and fibroblasts quickly infiltrated their porous microstructure. Echinoderm skeletal plates provide a simple, convenient alternative to coverslips and porous membranes for SEM or correlated SEM/TEM studies of cell behavior. More importantly, the preliminary evidence for biocompatibility presented suggests that native echinoderm skeleton has potential use as a biomaterial and, because of its microstructure and relative solubility; deserves evaluation as a kind of biodegradable ceramic.

Animals↗

PubMed1990

Aluminum-induced neo-osteogenesis: a generalized process affecting trabecular networking in the axial skeleton.

To determine if aluminum-induced neo-osteogenesis occurs in the axial skeleton, we compared spinal bone density and vertebral histology of beagles treated with aluminum for 8 and 16 weeks to that of untreated normals. Administration of aluminum (1.25 mg/kg) did not alter serum calcium, phosphorus, or creatinine but did result in a significant elevation of vertebral bone density, measured by quantitative computed tomography, after both 8 (286.7 +/- 12.4 mg/ml) and 16 (361.7 +/- 46.5 mg/ml) weeks of treatment compared with controls (212.2 +/- 4.5 mg/ml). In accord with the increased bone density, biopsies from the spine displayed evidence of neo-osteogenesis, including the presence of woven bone, both mineralized and unmineralized, within the marrow space. The genesis of such woven bone units resulted after 16 weeks in a significant increase in trabecular bone volume, woven and lamellar (51.2 +/- 4.4 versus 32.4 +/- 1.2%; p less than 0.05), woven bone volume (9.1 +/- 3.6 versus 0 +/- 0%; p less than 0.05), and trabecular number (4.5 +/- 0.3 versus 3.5 +/- 0.2 per mm; p less than 0.05). In addition, scanning electron microscopic evaluation of the bone biopsies confirmed the existence of new trabecular plates that provided interconnections between existent units. These observations illustrate that aluminum-induced neo-osteogenesis positively influences trabecular networking in the axial skeleton. Such enhancement of bone histogenesis contrasts with the effects of other pharmacologic agents that solely alter the thickness of existing trabecular plates or rods within the vertebral spongiosa.

Aluminum↗

PubMed2002

Origin and early evolution of vertebrate skeletonization.

Data from living and extinct faunas of primitive vertebrates imply very different scenarios for the origin and evolution of the dermal and oral skeletal developmental system. A direct reading of the evolutionary relationships of living primitive vertebrates implies that the dermal scales, teeth, and jaws arose synchronously with a cohort of other characters that could be considered unique to jawed vertebrates: the dermoskeleton is primitively composed of numerous scales, each derived from an individual dental papilla; teeth are primitively patterned such that they are replaced in a classical conveyor-belt system. The paleontological record provides a unique but complementary perspective in that: 1) the organisms in which the skeletal system evolved are extinct and we have no recourse but to fossils if we aim to address this problem; 2) extinct organisms can be classified among, and in the same way as, living relatives; 3) a holistic approach to the incorporation of all data provides a more complete perspective on early vertebrate evolution. This combined approach is of no greater significance than in dealing with the origin of the skeleton and, combined with recent discoveries and new phylogenetic analyses, we have been able to test and reject existing hypotheses for the origin of the skeleton and erect a new model in their place.

Animals↗

PubMed2003

Siliceous spicules and skeleton frameworks in sponges: origin, diversity, ultrastructural patterns, and biological functions.

Silica deposition is a fundamental process in sponges. Most sponges in the Classes Demospongiae and Hexactinellida secrete siliceous elements, which can subsequently fuse, interlock with each other, or form three-dimensional structures connected by spongin. The resulting skeletal frameworks allow sponges to grow upwards and facilitate water exchange with minimal metabolic cost. Several studies on sponge skeletogenesis have been published. We are beginning to understand the mechanisms of spicule secretion and the role of spicules and skeletal frameworks in the biology, ecology, and evolution of sponges. Molecular techniques and ecological experiments have demonstrated the genetic control of the process and the contribution of environmental factors to the expression of a sponge spicule, respectively. However, other classic topics such as the role of membranes in silicon transport or whether spicules are formed in situ or secreted anywhere in the sponge mesohyl and then transported to the skeletal framework require further investigation. We review the process of silica deposition in sponges at the molecular and cellular levels, as well as the biological and ecological functions of spicules and skeletons. The genetic control of spicule shapes makes them useful in the reconstruction of sponge phylogeny, although recent experiments have demonstrated the influence of environmental factors in modulating spicule size, shape, and the presence or absence of one or more spicule types. The implications of such variations in sponge taxonomy may be important. Besides supporting sponge cells, spicules can help larvae stay buoyant while in the plankton or reach the bottom at settlement, enhance reproduction success, or catch prey. Conversely, the role of spicules and skeletons in deterring predation has not been demonstrated. Knowledge of several aspects is still based on a single or a few species and extrapolations should be made only with caution. With the advent of new molecular techniques, new lines of research are presently open and active in this field.

Animals↗

PubMed2006

Postcranial skeleton of Shinisaurus crocodilurus (Squamata: Anguimorpha).

The postcranial skeleton is poorly known for Shinisaurus crocodilurus, the Chinese crocodile lizard. Discrepancies exist between published accounts of Shinisaurus; moreover, comparisons with complete specimens show important differences from the published descriptions. Contrary to some publications, the axial skeleton variably consists of 26 or 27 presacral vertebrae, including eight cervical vertebrae. Humeral entepicondylar and ectepicondylar foramina are present, as are an epipubis and hypoischium, and the post-tubercular portion of the pubis is subequal in length to the proximal portion. Sesamoids are present in the knee, elbow, and between the penultimate phalanges and unguals. A cartilaginous strut joins the clavicles and interclavicle. Comparative investigation of extant anguimorphs add context to these observations and support the conclusion that Mosasauroidea possessed eight or more (rather than seven) cervical vertebrae. Overall, the postcranium of Shinisaurus is relatively unspecialized for Anguimorpha, although it may be diagnosed accurately by a combination of character states.

Animals↗

PubMed2005

Magnetic resonance imaging of the axial skeleton enables objective measurement of tumor response on prostate cancer bone metastases.

BACKGROUND: There is currently no technique to image quantitatively bone metastases. Here, we assessed the value of MRI of the axial skeleton (AS-MRI) as a single step technique to quantify bone metastases and measure tumor response. METHODS: AS-MRI was performed in 38 patients before receiving chemotherapy for metastatic HRPCa, in addition to PSA, computed tomography of the thorax, abdomen, and pelvis [CT-TAP]; and Tc-99m bone scintigraphy. A second AS-MRI was performed in 20 patients who completed 6 months of chemotherapy. Evaluation of tumor response was performed using RECIST. RESULTS: Only 11 patients (29%) had RECIST measurable metastases in soft-tissues or lymph nodes on baseline CT-TAP. AS-MRI identified a diffuse infiltration of the bone marrow in 8 patients and focal measurable metastatic lesions in 25 patients (65%), therefore, doubling the proportion of patients with measurable lesions. Transposing RECIST on AS-MRI in 20 patients who completed 6 months of treatment, allows the accurate estimation of complete response (n = 2), partial response (n = 2), stable disease (n = 5), or tumor progression (n = 11), as it is done using CT-TAP in soft tissue solid metastases. CONCLUSIONS: MRI of axial skeleton enables precise measurement and follow-up of bone metastases as it is for other soft-tissue metastasis.

Bone Neoplasms↗

PubMed1993

Biogenesis of erythrocyte membrane skeleton in health and disease.

To study the biogenesis of red cell membrane skeleton at various stages of erythroid differentiation, we have chosen the following model systems: a) Rauscher erythroleukemia cell line representing the early stages of differentiation, b) Friend erythroleukemia cells, and c) in vitro cultured human erythroblasts. The latter two systems represent terminally differentiated erythroblasts. Using these model systems, we have shown asynchronous synthesis of membrane proteins during erythroid differentiation. At the early stages of erythroid development, the synthesis of spectrin, ankyrin and band 4.1 proteins is initiated before that of the band 3 protein. Following erythroid induction with erythropoietin and dimethylsulfoxide (DMSO), there is a dramatic increase in the synthesis of the band 3 protein without noticeable changes in the synthesis of other membrane proteins. This increase in band 3 synthesis is accompanied by increased stability and recruitment of the skeletal proteins into the membrane skeleton, leading to increased steady state levels. The progressive increase in band 3 synthesis continues during terminal maturation of erythroblasts. This is accompanied by increased stability and assembly of spectrin and ankyrin on the membrane, despite their reduced synthesis. These results point to a key role for the band 3 protein in anchoring and stabilizing these proteins into the permanent skeletal network. Finally, to detect defects of skeletal biosynthesis, we have extended these studies to a patient with severe hereditary spherocytosis characterized by a combined deficiency of spectrin and ankyrin. We have shown that this combined deficiency is a consequence of reduced ankyrin synthesis and mRNA content representing a thalassemia-like membrane protein mutation.

Animals↗

PubMed2004

Biosynthetic studies of the DSP toxin skeleton.

Marine toxins have drawn wide interest because their economical impact and disastrous effect upon the shellfish industry and public health in many parts of the world. One of the most interesting group of substances of marine toxins, from structural and pharmacological points of view are polyether compounds, which generally present a great diversity in size and potent biological activities. The subject of this work was about to biosynthesis of okadaic acid skeleton as leader as DSP toxins. Its biosynthesis attracts considerable attention since the carbon skeleton has been shown to be synthesised via an unusual route. In this paper we report on stable isotope incorporation experiments on DSP toxin in artificial cultures of dinoflagellate. The comparison of the degrees of incorporation in these samples measured by different methods led to contradictory results. This implies that further experimental data is needed in order to propose a logical biogenetic scheme.

Animals↗

PubMed2001

Atlas of rat fetal skeleton double stained for bone and cartilage.

BACKGROUND: The double staining of fetal skeleton for bone and cartilage is a very useful method to evidence skeletal abnormalities in laboratory animals. However, this method has been rarely used in routine developmental toxicity tests. One reason could be the difficulty of comparing the single skeletal pieces and of having reference points. In this paper the fetal rat skeleton double stained with Alizarin red S and Alcyan Blue is described in detail to produce an atlas for developmental toxicity laboratories.

Alcian Blue↗

PubMed1983

Assessment of adult skeletons to detect prenatal exposure to trypan blue in mice.

A Skeletal Variant Assay System (SVAS) consisting of a group of 88 spontaneously occurring qualitative variations of the adult mouse skeleton was studied in CD-1 mice which had been exposed in utero by way of three daily ip injections of their dams on days 7-9 of gestation with trypan blue. Treatment groups received daily doses of 0.25 cc of 0, .037, .075, .15, or .30% trypan blue dissolved in 0.9% NaCl. Two separate series of experiments were performed, and skeletons were examined at 62 +/- 2 days postnatal. Sixty-six and 58 of the variants occurred in the two series, respectively. Frequencies of occurrence of substantial numbers of variants differed from Untreated (UNTD) and Vehicle-Treated (VEH) values in a dose-related manner for both series. At the high dose 18 and 22 variants occurred with significantly different (P less than .01) frequencies from UNTD in the two series. Contrasting high-dose animals with vehicle controls revealed significant differences in 24 and 17 variants. There were 13 and 14 variants in the two series, respectively, which differed from both UNTD and VEH. If one considers differences at P less than .01 in one comparison and P less than .05 in the other, then 22 and 18 variants qualify as being significantly different from both controls in the two series. Agreement between the two series was excellent regarding which variants were affected. Several differed significantly from both UNTD and VEH in both series of experiments. Among these were a number which appeared more or less specific to trypan blue exposure. They include Dyssymphysis of the Atlas, Carpal Fusions, and Tarsal Fusions. Although increased frequency of an Interfrontal bone is seen with several treatments, the magnitude of the response and the low doses at which it is elicited are unique to trypan blue exposure. Numerous low-dose effects are striking in this set of experiments, making the SVAS a very sensitive indicator of trypan blue exposure. In addition to the variants mentioned, a large cluster of cervical (C) vertebrae variants, including dyssymphyses, fusions, imperfect transverse foramina of C1 and C2, and accessory transverse foramina of C3-C6, as well as vertebral fusions at various levels (especially cervical, sacral, and caudal), appear to be the principal effects of exposure to this compound. In addition, rib malformations at the high dose level, and increased frequency of occurrence of 27-presacral vertebrae at all dose levels, were important effects.(ABSTRACT TRUNCATED AT 400 WORDS)

Abnormalities, Drug-Induced↗

PubMed1994

Enhanced expression of limb malformations and axial skeleton alterations in legless mutants by transplacental exposure to retinoic acid.

This manuscript reports on the limb malformations and axial skeleton alterations found in legless fetuses and their heterozygote and wild-type littermates transplacentally exposed to all-trans-retinoic acid via a single intraperitoneal injection on Day 7, 8, 9, 9.5, 10, 10.5, or 11 of gestation. The most surprising aspect of the results was the temporal sensitivity of the legless mouse limb to exogenous retinoic acid. On Day 11, when both fore- and hindlimbs of nonmutant embryos can be made abnormal by retinoic acid and other teratogens, retinoic acid did not increase the frequency or severity of legless hindlimb defects and forelimb malformations were only slightly enhanced. On the other hand, retinoic acid administration on Day 7 exacerbated forelimb malformations in legless fetuses at a time when visible emergence of the affected structure is still 48 hr away. Heterozygote and wild-type fetuses had no limb malformations at this time point. A similar phenomenon was observed with hindlimb malformations after retinoic acid exposure on Day 8 except for a few mild limb malformations in heterozygotes at a high dose of retinoic acid. This early hypersensitivity of fore- and hindlimbs was followed by a period of reduced sensitivity (Day 8 forelimb; Day 9 hindlimb) when even very high doses (50 mg/kg) induced minimal changes in the typical legless malformation pattern. Subsequently, at the time of visible limb bud emergence (Day 9 forelimbs; Day 10 hindlimbs), sensitivity to exogenous retinoic acid was again detected. Surprisingly, the altered malformation patterns induced by retinoic acid in lgl mutants were nearly identical to those from earlier, pre-emergence exposure. A number of axial skeleton alterations were induced in legless fetuses by retinoic acid, especially after exposure on Days 7, 8, or 9. Posterior truncations were particularly noteworthy, showing a graded response in which frequency and severity of truncation were worst in lgl/lgl fetuses; heterozygotes gave an intermediate response, and wild-type fetuses were least affected. This exacerbation of the legless phenotype by exogenous retinoic acid coupled with the similarity between legless and retinoid malformations suggest that the legless mutation has altered endogenous retinoid homeostasis or a downstream retinoid-responsive gene.

Abnormalities, Drug-Induced↗

PubMed1995

Mutations in paralogous Hox genes result in overlapping homeotic transformations of the axial skeleton: evidence for unique and redundant function.

Hoxd-4 (previously known as Hox-4.2 and -5.1) is a mouse homeobox-containing gene homologous to the Drosophila homeotic gene Deformed. During embryogenesis, Hoxd-4 is expressed in the presumptive hindbrain and spinal cord, prevertebrae, and other tissues. In the adult, Hoxd-4 transcripts are expressed predominantly in the testis and kidney, and to a lesser extent in intestine and heart. To understand the role of Hoxd-4 during mouse embryogenesis, we generated Hoxd-4 mutant mice. Mice heterozygous or homozygous for the Hoxd-4 mutation exhibit homeotic transformations of the second cervical vertebrae (C2) to the first cervical vertebrae (C1) and malformations of the neural arches of C1 to C3 and of the basioccipital bone. The phenotype was incompletely penetrant and showed variable expressivity on both an F2 hybrid and 129 inbred genetic background. The mutant phenotype was detected in the cartilaginous skeleton of 14.5-day (E14.5) mutant embryos but no apparent differences were detected in the somites of E9.5 mutant embryos, suggesting that the abnormalities develop after E9.5 perhaps during or after resegmentation of the somites to form the prevertebrae. These results suggest that Hoxd-4 plays a role in conferring position information along the anteroposterior axis in the skeleton. The phenotypic similarities and differences between Hoxd-4 and previously reported Hoxa-4 and Hoxb-4 mutant mice suggest that Hox gene paralogs have both redundant and unique functions.

Animals↗

PubMed1982

Skeletal metastasis: the effect on the immature skeleton.

The unique opportunity to study the entire appendicular skeleton of a child who died from metastatic angiosarcoma allowed detailed assessment of radiographically evident involvement. Virtually every portion of the appendicular skeleton had evidence of metastatic disease. However, the extent of involvement was extremely variable, especially when contralateral regions were assessed. The most likely region of metastasis, the metaphysis, is normally a fenestrated cortex of woven bone in the young child, rather than a well demarcated cortex formed by osteon (lamellar) bone, as it is in the adult. The pattern of destruction is such that less extensive areas may be involved before becoming radiographically evident, and trabecular bone involvement may be evident even without cortical damage. The metaphyseal metastatic spread supports the concept of arterial hematogenous dissemination, comparable to osteomyelitis in the child. Pathologic metaphyseal fractures involved both proximal humeri; the fracture also extended along a portion of the metaphyseal-physeal interface in one humerus. In one distal femur the physis readily separated from the metaphysis; this was a non-displaced type 1 growth mechanism injury.

Bone Neoplasms↗

PubMed1990

The prenatal development of the normal human skeleton: a combined ultrasonographic and post-mortem radiographic study.

Post-mortem radiography of fetuses with skeletal dysplasia is essential for diagnostic classification. Interpretation of the radiographs should be based on the knowledge of morphology and dimensions of the normal skeleton in all stages of development. A retrospective post-mortem radiographic study is presented with measurements of the lengths of the long bones and thoracic and lumbar spine. The study included 69 fetuses and neonates with a normal skeleton, whose gestational age ranged from 13-42 weeks and who died perinatally or lived for less than one week. The measurements of the long bones were plotted on growth curves obtained from a prospective longitudinal ultrasonographic investigation of another group of 63 normal fetuses from 12-40 weeks of gestation. Thoracic and lumbar spine measurements by ultrasonography were not available. The radiographic data of thoracic and lumbar spine were, therefore, compared to radiographic studies from the literature. No disagreement with these studies was found. It can be concluded that measurements of bones from standardized post-mortem radiographs in cases of questionable gestational age or defects of bone development can be compared with ultrasonographic measurements. To illustrate the usefulness of the graphs, 13 fetuses with various types of skeletal dysplasia were evaluated retrospectively.

Bone Diseases, Developmental↗

PubMed1987

Regional variations in histomorphometric bone dynamics from the skeleton of an osteoporotic woman.

Histomorphometric evaluation of bone formation in an intravital tetracycline-labeled skeleton of a suddenly deceased osteoporotic woman is presented. The 24 skeletal sites investigated displayed substantial regional variations which, for two out of four cortical bone dynamics and all trabecular bone dynamics, were significantly higher than the intraspecimen variation. Poor agreement was found between bone formation in left- and right-sided iliac crest specimens. Furthermore, no agreement was found between trabecular bone formation and amount of hematopoietic bone marrow. With all the limitations that the study of a single patient involves it is suggested that bone biopsy in individual patients should not be the only basis for therapeutic decisions in postmenopausal osteoporosis; amount of hematopoietic marrow does not seem to influence bone formation; and bone formation in the skeleton displays large regional variations, which are larger for the fraction of labeled surfaces than for appositional rate.

Aged↗

PubMed1999

Persistence of bone collagen cross-links in skeletons of the Nuraghi population living in Sardinia 1500-1200 B.C.

Bone collagen has a specific molecular ultrastructure which can be proved by birefringence. This protein, forming the main organic component of bone tissue, is known to survive millennia in paleontological bones and teeth. Birefringence of bone collagen obtained from the skeletons of the Nuraghi population living in Sardinia c-ca 1500 years B.C. was found previously by the use of polarizing microscopy [1]. In this paper, using high pressure liquid chromatography (HPLC) techniques, we show the existence of bone collagen cross-links preserved in Nuraghi skeletons after more than 3000 years.

Amino Acids↗

PubMed2003

Targeting of the Akt/PKB kinase to the actin skeleton.

Serine/threonine kinase Akt/PKB intracellular distribution undergoes rapid changes in response to agonists such as Platelet-derived growth factor (PDGF) or Insulin-like growth factor (IGF). The concept has recently emerged that Akt subcellular movements are facilitated by interaction with nonsubstrate ligands. Here we show that Akt is bound to the actin skeleton in in situ cytoskeletal matrix preparations from PDGF-treated Saos2 cells, suggesting an interaction between the two proteins. Indeed, by immunoprecipitation and subcellular fractioning, we demonstrate that endogenous Akt and actin physically interact. Using recombinant proteins in in vitro binding and overlay assays, we further demonstrate that Akt interacts with actin directly. Expression of Akt mutants strongly indicates that the N-terminal PH domain of Akt mediates this interaction. More important, we show that the partition between actin bound and unbound Akt is not constant, but is modulated by growth factor stimulation. In fact, PDGF treatment of serum-starved cells triggers an increase in the amount of Akt associated with the actin skeleton, concomitant with an increase in Akt phosphorylation. Conversely, expression of an Akt mutant in which both Ser473 and Thr308 have been mutated to alanine completely abrogates PDGF-induced binding. The small GTPases Rac1 and Cdc42 seem to facilitate actin binding, possibly increasing Akt phosphorylation.

3-Phosphoinositide-Dependent Protein Kinases↗

PubMed1999

Effects of menopause on age-dependent bone loss in the axial and appendicular skeletons in healthy Japanese women.

To determine the effects of menopause on bone loss in different parts of the skeleton, bone mineral density (BMD) values were measured longitudinally in 85 healthy women. BMD values included the lumbar spine measured by dual-energy X-ray absorptiometry (DXA) and quantitative CT (QCT) and the distal and midradius measured by DXA obtained over 5 years. BMD at the calcaneus was measured using DXA for 3 years, and the BMD values of the distal metaphyses and diaphyses of radius and tibia were measured using peripheral QCT (pQCT) for 4 years. The subjects were 19 premenopausal, 17 perimenopausal, 12 early postmenopausal and 38 late postmenopausal women with the respective average ages of 39.1 +/- 7.1 (SD), 51.9 +/- 2.9, 55.8 +/- 1.8 and 61.9 +/- 3.9 years at the start of measurement. Average years since menopause were 1.4 +/- 1.8, 3.3 +/- 1.3 and 12.7 +/- 5.3 years, respectively. In the perimenopausal group, the annual rate of bone loss for lumbar trabecular bone measured by QCT, and for the calcaneus, and metaphyseal trabecular bone at the radius and tibia by pQCT were higher than the respective values in the premenopausal group. These values in the late postmenopausal group became significantly lower compared with those in the perimenopausal group, coming down to the level of the premenopausal group. While the annual rates of bone loss at the tibial diaphysis in the perimenopausal group were also higher than those in the premenopausal group, the values at the radial diaphysis by DXA or pQCT did not differ significantly. The reductions in the annual rates of bone loss with the passage of time after menopause were not marked in these cortical bone dominated sites. These data indicated that the annual rates of bone loss at trabecular bone dominated sites were accelerated in both axial and appendicular skeletons. Diaphyseal cortical bone, however, seemed to be less sensitive to estrogen withdrawal. Other factors, such as genetics and calcium/vitamin D metabolism, would also affect the age-dependent bone loss at the cortical bone dominated sites after menopause.

Absorptiometry, Photon↗