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 433 records · Page 24Linked to original sources

PubMed1990

Antigen-induced cross-linking of the IgE receptor leads to an association with the detergent-insoluble membrane skeleton of rat basophilic leukemia (RBL-2H3) cells.

Cross-linking of the IgE receptor on the surface of rat basophilic leukemia cells by multivalent Ag (DNP-BSA) causes a rapid conversion to a detergent-insoluble form. There is a concurrent increase in the amount of filamentous actin associated with the plasma membrane. Both the degree of receptor detergent insolubility and the rise in F-actin content are rapid with a half-maximal response of less than 1 min and can be rapidly reversed by the addition of monovalent Ag (DNP-lysine). These two early steps in the triggering of rat basophilic leukemia cells can be dissociated from each other by pretreatment of the cells with either cytochalasin or sodium azide. These reagents block the increase in F-actin but have no effect on receptor detergent insolubility. This indicates that microfilaments are not responsible for detergent insolubility of the receptor and that it may be the membrane skeleton that is interacting with the complex. This was further confirmed by the finding that cross-linking of the IgE receptors on the surface of purified plasma membranes also leads to detergent insolubility of the receptor. Therefore, all of the components necessary for detergent insolubility of the receptor are present in the plasma membrane, and cytoplasmic components are not needed. These results suggest that detergent insolubility and immobility of the cross-linked receptors are caused by multivalent interaction with the membrane skeleton. Actin filaments may then interact with these receptor-membrane skeletal complexes in order to produce large scale clustering and capping. The membrane skeleton may therefore be acting as an intermediate structure between the cell-surface receptors and microfilaments.

Actin Cytoskeleton↗

PubMed1990

Is there any role of membrane bilayer-skeleton interaction in maintaining the transmembrane phospholipid asymmetry in erythrocytes?

Erythrocyte membrane phospholipids are asymmetrically distributed in two surfaces of the membrane bilayer. This asymmetry in these cells, on one hand, has been considered to arise from the membrane skeleton-bilayer interactions, while on the other, it has been thought to originate from an ATP-dependent aminophospholipid pump. A critical analysis of these two proposals, in the light of the existing literature, reveals that neither the membrane skeleton nor the aminophospholipid pump is adequate per se to maintain the phospholipid asymmetry. Instead, evidence is presented to show that the phospholipid pump together with the membrane skeleton is required for generation and maintenance of the transmembrane phospholipid asymmetry in native erythrocytes.

Adenosine Triphosphate↗

PubMed1989

Bone structural parameters, dosimetry, and relative radiation risk in the beagle skeleton.

A variety of morphometric and histomorphometric parameters such as the mass of bone and marrow, bone surface areas, percentage of bone volume, percentage of the surface that is trabecular, and percentage of surfaces that are forming and resting are calculated for all major parts of the beagle skeleton. The total bone surface of the beagle is estimated at 2.9 m2 with 53.7% of the surface area being associated with trabecular bone. There are about 4.5 x 10(9) bone-lining cells and about 1 x 10(9) osteoblasts. From the fractional retention in each part of the skeleton, the initial surface concentration of 239Pu after a single injection of 592 Bq/kg body wt (0.016 microCi/kg) on resting surfaces and at sites of bone formation is calculated for various values of the affinity ratios of trabecular/cortical and forming/resting surfaces. These estimated concentrations then yield dose rates as well as cumulative and collective doses to bone-lining cells and osteoblasts in the different parts of the skeleton. On the assumption that the relative risk of tumor induction is proportional to the collective dose to either bone-lining cells or osteoblasts, the frequency of tumor occurrence is calculated and compared to observed frequencies. Both hypotheses yield approximate agreement with experimental data for different ratios of trabecular/cortical radiation sensitivity, although the differences between some bones are statistically significant.

Animals↗

PubMed1986

Photoperiod and body weight in female Syrian hamsters: skeleton photoperiods, response magnitude, and development of photorefractoriness.

Two experiments examined the effects of various photoperiods on body weight and reproductive function in Syrian hamsters (Mesocricetus auratus). In Experiment 1 female hamsters were exposed to symmetrical skeleton photoperiods in which dawn and dusk were mimicked by 1-hr light pulses. A skeleton long (LD 16:8) photoperiod had no effect on body weight or estrous cyclicity (compared with animals in a complete LD 16:8 photoperiod), but exposure to a skeleton short (LD 10:14) photoperiod increased body weight and interrupted estrous cycles. Thus, body weight appears to respond to the relative timing of the two light pulses (a circadian mechanism) rather than to the absolute amount of light or darkness (an hourglass mechanism), just as does reproduction. In Experiment 2 female hamsters were exposed to a long photoperiod (LD 16:8) or to one of two short photoperiods (LD 10:14 and LD 8:16). Both short photoperiods increased body weight and interrupted estrous cycles, but the LD 8:16 photoperiod was substantially more effective at increasing body weight than was the LD 10:14. Thus, hamster body weight appears to be capable of a graded response to photoperiod, with shorter days producing a greater obesity. With prolonged exposure to the two short photoperiods (greater than 30 weeks), body weights spontaneously returned to the same level as the long-day controls, and estrous cycles resumed. When these hamsters were treated with the pineal gland hormone, melatonin, only those housed in long days exhibited the characteristic body weight gains, growth of brown and white adipose tissues, and decreases in uterine weight. Therefore, with prolonged exposure to short days, energy balance develops a photorefractoriness and an insensitivity to melatonin treatment, just as with reproductive function.

Adipose Tissue, Brown↗

PubMed1977

The degree of bone mineralization in different parts of human skeleton estimated from bone phosphorus/hydroxyproline.

To evaluation the uniformity of the degree of mineralization in the skeleton the bone phosphorus/hydroxyproline ratio (bone P/Hypro) was determined in different localizations of ten human skeletons. Marked differences in bone P/Hypro were found between cortical bone and spongy bone. No difference was found between cortical bone from humerus, femur and cranium. But the mean value of these cortical bones was significantly higher than the mean value of the studied spongy bones. No significant correlation was found between the two bone types. Differences in bone P/Hypro were also found between different spongy bones. In pelvis the value did not differ between four spongy bone localizations but the mean value was significantly lower than for the other spongy bones (thoracal column, lumbal column and clavicle). Between these other spongy bones no difference was found in mean bone P/Hypro, and the mean of the pelvic bone localizations correlated significantly to the other spongy bones. The study demonstrates differences in the chemical composition of the human skeleton. A value of bone P/Hypro in the iliac crest can be used to estimation of bone P/Hypro in other spongy bones but not in cortical bones.

Adult↗

PubMed1984

[Identification of the skeleton of Georg Christoph Lichtenberg].

To reveal the morbidity of George Christoph Lichtenberg, his skeleton was exhumed in May 1983. This paper deals with the identification of the skeleton as well as with its pathology. Since Lichtenberg left detailed knowledge about his bodily appearance in his own writings, and so did his contemporaries, the identity of the skeleton can be taken for sure because of the good correspondence of several morphological and pathological features.

Bone Diseases↗

PubMed1984

Association of Rho(D) polypeptides with the membrane skeleton in Rho(D)-positive human red cells.

The Rho(D) antigen was recently identified as a 28,000 to 33,000 m.w. polypeptide expressed on the surface of human Rho(D)+ cells. We now show that 70 to 80% of the Rho(D) polypeptides remain firmly associated with the membrane skeleton (detergent-insoluble matrix) obtained after treatment of isolated membranes with Triton X-100. The same treatment solubilized most of the major sialoglycoprotein, glycophorin A. The membrane skeleton-bound Rho(D) polypeptides were not solubilized by procedures that dissociated spectrin, actin, and glyceraldehyde-3-phosphate dehydrogenase from the membrane. Affinity-purified 125I-labeled anti-Rho(D) antibodies bound to intact Rho(D)+ cells, Rho(D)+ membranes, and isolated membrane skeletons from Rho(D)+ cells, but not to Rho(D)- cells. The binding to Rho(D)+ cells was competitively inhibited efficiently by Rho(D)+ membranes and weakly by Rho(D)- membranes. When isolated unsealed Rho(D)+ and Rho(D)- membranes were labeled by lactoperoxidase-catalyzed iodination and solubilized in Triton X-100, Rho(D) polypeptides were immune precipitated only from Rho(D)+ membranes.

Antigen-Antibody Complex↗

PubMedDate not supplied

[Two types of attachment points of DNA to the nuclear skeleton in Ehrlich ascites carcinoma cells].

Two types of DNA fragments attached to the nuclear skeleton and protected from staphylococcal nuclease digestion by the nuclear skeleton's proteins were found in Ehrlich ascites carcinoma cells: (i) long (approximately 10 kb) satellite DNA fragments and (ii) short (approximately 140 b. p.) main band DNA fragments. The amount of short DNA fragments depends strongly on the conditions of nuclei isolation. In the preparations obtained from the cells lysed in the medium lacking Cu2+ or Zn2+ short DNA fragments were not found. On the contrary long satellite DNA fragments were found in presumably equal amounts in the nuclei obtained by a wide variety of experimental procedures. Different stability of the structures providing attachment and protection from nuclease digestion of long and short DNA fragments seem to be a good reasons to suggest the existence of two types of attachment points of DNA to the nuclear skeleton.

Animals↗

PubMed1993

[The effect of weightlessness on amphibians. The skeleton and mineral metabolism].

The visceral and somatic skeleton of Pleurodeles waltilii was investigated after a series of two-week space flights on the biosatellites. It was shown that under conditions of weightlessness osteoporosis of the skeleton and its demineralisation were stimulated. In weightlessness, calcium, phosphorus and sulfur were lost and potassium accumulated. Trabeculae of endochondral part of the extremity bones were destroyed by osteoclasts. Proliferation of osteoclasts was disrupted, appositional growth stopped, and the cartilage of hyoid system was resorbed. Skeleton readaptation during two months did not result in the complete regeneration of morphological structure of the bones.

Adaptation, Physiological↗

PubMed1995

Molecular basis of altered red blood cell membrane properties in Southeast Asian ovalocytosis: role of the mutant band 3 protein in band 3 oligomerization and retention by the membrane skeleton.

Southeast Asian ovalocytosis (SAO) is an asymptomatic trait characterized by rigid, poorly deformable red cells that resist invasion by several strains of malaria parasites. The underlying molecular genetic defect involves simple heterozygous state for a mutant band 3 protein, which contains a deletion of amino acids 400 through 408, linked with a Lys 56-to-Glu substitution (band 3-Memphis polymorphism). To elucidate the contribution of the mutant SAO band 3 protein to increased SAO red blood cell (RBC) rigidity, we examined the participation of the mutant SAO band 3 protein in increased band 3 attachment to the skeleton and band 3 oligomerization. We found first that SAO RBC skeletons retained more band 3 than normal cells and that this increased retention preferentially involved the mutant SAO band 3 protein. Second, SAO RBCs contained a higher percentage of band 3 oligomer-ankyrin complexes than normal cells, and these oligomers were preferentially enriched by the mutant SAO protein. At the ultrastructural level, the increased oligomer formation of SAO RBCs was reflected by stacking of band 3-containing intramembrane particles (IMP) into longitudinal strands. The IMP stacking was not reversed by treating SAO RBCs in alkaline pH (pH 11), which is known to weaken ankyrin-band 3 interactions, or by removing the cytoplasmic domain of band 3 from SAO membranes with trypsin. Finally, we found that band 3 protein in intact SAO RBCs exhibited a markedly decreased rotational mobility, presumably reflecting the increased oligomerization and the membrane skeletal association of the SAO band 3 protein. We propose that the mutant SAO band 3 has an increased propensity to form oligomers, which appear as longitudinal strands of IMP and exhibit increased association with membrane skeleton. This band 3 oligomerization underlies the increase in membrane rigidity by precluding membrane skeletal extension, which is necessary for membrane deformation.

Anion Exchange Protein 1, Erythrocyte↗

PubMed1994

Regulatory interaction of N-formyl peptide chemoattractant receptors with the membrane skeleton in human neutrophils.

The cytoskeleton and/or membrane skeleton has been implicated in the regulation of N-formyl peptide receptors. The coupling of these chemotactic receptors to the membrane skeleton was investigated in plasma membranes from unstimulated and desensitized human neutrophils using the photoreactive agonist N-formyl-met-leu-phe-lys-N epsilon-[125I]2(p-azidosalicylamido)ethyl-1,3'- dithiopropionate (fMLFK-[125I]ASD). When membranes of unstimulated cells were solubilized in Triton-X 100, a detergent that does not disrupt actin filaments, only 50% of the photoaffinity-labeled receptors were solubilized sedimenting in sucrose density gradients at a rate consistent with previous reports. The remainder were found in the pellet fraction along with the membrane skeletal actin. Solubilization of the membranes in the presence of p-chloromercuriphenylsulfonic acid, elevated concentrations of KCl, or deoxyribonuclease I released receptors in parallel with actin. When membranes from neutrophils, desensitized by incubation with fMLFK-[125I]ASD at 15 degrees C, were solubilized, nearly all receptors were recovered in the pellet fraction. Incubation of cells with the ligand at 4 degrees C inhibited desensitization partially and prevented the conversion of a significant fraction of receptors to the form associated with the membrane skeletal pellet. In these separations the photoaffinity-labeled receptors not sedimenting to the pellet cosedimented with actin. Approximately 25% of these receptors could be immunosedimented with antiactin antibodies suggesting that N-formyl peptide receptors may interact directly with actin. These results are consistent with a regulatory role for the interaction of chemotactic N-formyl peptide receptors with actin of the membrane skeleton.

Actin Cytoskeleton↗

PubMed1997

A membrane skeleton that clusters nicotinic acetylcholine receptors in muscle.

We have presented ultrastructural and semiquantitative immunofluorescence evidence to support the idea that AChR are clustered in rat myotubes by virtue of their ability to associate with a spectrin-based membrane skeleton. Many of the interactions postulated to be involved in the formation of this skeleton, and in the anchoring of AChR to it, must still be examined at the biochemical level, but the overall similarity of this structure to that of the human erythrocyte is already clear. The ability of different members of the spectrin superfamily to associate in various combinations to form distinct plasmalemmal domains provides some exciting hints as to how the surface membrane can be organized efficiently to subserve multiple purposes. One of the challenges of future research will be to learn how innervation regulates the assembly of the membrane skeleton at the developing NMJ, and how this structure is altered as the junction matures. Another will be to learn if the principles of neuromuscular synaptogenesis are relevant to interactions between neurons in the brain, where cells must distinguish between multiple synaptic inputs and assemble synaptic structures at thousands of distinct sites on the neurolemma. Members of the spectrin superfamily have been identified in synaptic structures in the central nervous system (e.g., Carlin et al., 1983; LeVine and Sahyoun, 1986; Malchiodi-Albedi et al., 1993), so much of what we have learned at the neuromuscular junction may be applicable to central synapses.

Animals↗

PubMed1981

Bone mineral-osteon analysis of Yupik-Inupiaq skeletons.

Living adult Eskimos from St. Lawrence Island, North Alaska, and Canada undergo an earlier and more rapid rate of age-related bone mineral loss compared to U.S. whites. Further, it has been shown that Eskimos and Indians differ in patterns of osteon remodeling at the Haversian envelope. Femoral bone cores from adult Eskimos skeletons from St. Lawrence Island (n = 53), Kodiak Island (n = 92), Baffin Island (n = 44), and Southampton Island (n = 69) were analyzed and the results compared with those obtained from cores from U.S. whites (n = 144). Cortical thickness, bone mineral content of cores, cortical bone density, secondary osteon and Haversian canal number and area were quantified for each core. Ages at death were estimated by histological methods and compared with the ages at death estimated by morphological methods for the Eskimo skeletons. Known ages at death were compared with histologically estimated ages at death for the U.S. white series. St. Lawrence Island and Kodiak Island (Yupik speakers) Eskimo cortical thickness values were significantly (P less than .05) greater than Baffin Island and Southampton Island (Inupiaq speakers) Eskimos cortical thickness values but less than the cortical thickness values for U.S. whites. The bone mineral content of the Southampton Eskimos femoral cores was the lowest found in this study. Histological analysis of the femoral bone sections showed that Eskimos contain more osteons per unit area than U.S. whites. No differences in osteon size were noted between the two populations. Differences in patterns of osteon remodeling between Eskimos and whites were inferred. Age at death estimation by histological methods in Eskimos using U.S. white regression equations yielded age estimates in poor agreement with those obtained by morphological methods.

Age Determination by Skeleton↗

PubMed1985

Atlanto-occipital fusion and spondylolisthesis in an Anasazi skeleton from Bright Angel Ruin, Grand Canyon National Park, Arizona.

The skeleton of a middle-aged female showing an unusual pattern of congenital, traumatic, and degenerative pathology was recovered from a small Kayenta Anasazi site located near the confluence of Bright Angel Creek with the Colorado River in the Inner Gorge of Grand Canyon. The atlas is fused with the base of the skull and C2 is fused with C3. The cervical region was subjected to hyperextension, perhaps through use of a tumpline, with resultant reduction of the neural canal to 8 mm, a condition that quite likely led to neurological problems. The skeleton also includes a depression fracture of the lateral condyle of the left tibia. Complete, bilateral spondylolysis of L5 led to an olisthesis of approximately 15 mm. The disc between L5 and S1 then ossified, most likely from staphylococcus bacteremia, making the olisthesis permanent and thereby creating a unique arachaeological specimen. Although spondylolysis is usually viewed as a stress fracture, the general pattern of pathology in this individual makes it necessary to consider an etiology of acute trauma.

Arizona↗

PubMed2005

Coexistence of melorheostosis and DISH in a female skeleton from Magna Graecia (Sixth Century BC).

This paper reports on a case of massive hyperostotic alterations observed in the skeleton of an adult woman from the necropolis of Montescaglioso Belvedere (Basilicata, Southern Italy) attributed to the Enotrian culture and dated to the 6th century BC. Hyperostotic changes involve joints, the vertebral column, and the lower limbs. In particular, the large flowing ossification in both the thoracic (T6-T10) and lumbar (L2-L5) tracts, the sacralization of L5, accompanied by sacroiliac fusion on the left side, and the proliferative bone production on both the metaphyseal portion of the left tibia and the left third metatarsal are described. The vertebral antero-lateral ossification and the sacroiliac fusion support a diagnosis of diffuse idiopathic skeletal hyperostosis (DISH), while the flowing bone formation on the lower limbs supports a diagnosis of melorheostosis. The pathological conditions described here were already described in the literature, but this is the first reported case of the coexistence of DISH and the very rare melorheostosis. Furthermore, the skeleton from Montescaglioso Belvedere represents the first case of this disease described for ancient Europe, therefore adding a valuable contribution to the reconstruction of the antiquity and distribution of skeletal dysplasias.

Female↗

PubMed2003

Functional-adaptive anatomy of the axial skeleton of some extant marsupials and the paleobiology of the paleocene marsupials Mayulestes ferox and Pucadelphys andinus.

In this study, the axial skeletons of two Early Paleocene marsupials, Mayulestes ferox and Pucadelphys andinus, were analyzed functionally and compared to that of six South American and three Australian species of extant marsupials. In the case of the South American opossums, myological data of the epaxial musculature were collected and analyzed and osteological-myological associations were related to locomotor behavior. Various features of the vertebral column that relate to diet or to locomotor or postural patterns were pointed out. These features include: the craniocaudal development of the neural process of the axis; the position of the anticlinal vertebra; the morphology of the neural processes of the thoracolumbar vertebrae (orientation, length, and craniocaudal width); the length, orientation, and curvature of the transverse processes of the lumbar vertebrae; and the length and robustness of the caudal vertebrae. In both fossil forms the vertebral column is mobile and allows a great range of flexion and extension of the spine, more so than in most of the living didelphids. It is emphasized here that the analysis of the axial skeleton complements and improves the conclusions provided by the forelimb and hindlimb analyses. It is proposed that Mayulestes and Pucadelphys represent an ancestral morphotype suggesting that the generalized type of locomotion of Paleocene marsupials was partly terrestrial with some climbing ability.

Adaptation, Physiological↗

PubMed2005

Leis' conundrum: homology of the clavus of the ocean sunfishes. 1. Ontogeny of the median fins and axial skeleton of Monotrete leiurus (Teleostei, Tetraodontiformes, Tetraodontidae).

We describe the ontogeny of the axial skeleton and median fins of the Southeast Asian freshwater puffer Monotrete leiurus, based on a reared developmental series. Most elements of the axial skeleton in M. leiurus arise in membrane bone. Only the base of the anterior three neural arches, the base of the hemal arches of the third preural centrum, the neural and hemal arches and spines of the second preural centrum, the parhypural, the two hypural plates, and the single epural are preformed in cartilage. In contrast to most teleosts, the proximal-middle radials of the dorsal and anal fins are upright and symmetrical and their distal tips coalesce during development to form a deep band of cartilage, from which the spherical distal radials are spatially separated.

Anatomy, Comparative↗

PubMed1986

[Determination of age based on the skeleton].

A skeleton is reported that was found 40-100 cm under the surface of the earth; the light, porous bones had partially fallen to pieces. The most remarkable point was the discrepancy between the age of the bone and that of the teeth: based on the bones, the age of the living human being was about 30-40 years; on the basis of the teeth, however, the person was much older. The matter was cleared up with the help of a neck chain that was a precursor to the torques worn by the Celts; thus the skeleton was about 2500 years old. As the teeth were worn down much more through more use in prehistoric times than they are today, the age of the living person is likely to be the bone age, which was about 35 years.

Adult↗