SEARCH · Search PubMed

Results for “Skeleton”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

SourceResearch connectionFrom yearThrough year

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

At least 685 records · Page 38Linked to original sources

PubMed1994

Elastin exhibits a distinctive temporal and spatial pattern of distribution in the developing chick limb in association with the establishment of the cartilaginous skeleton.

In this work we have analyzed the presence of elastic components in the extracellular matrices of the developing chick leg bud. The distributions of elastin and fibrillin were studied immunohistochemically in whole-mount preparations using confocal laser microscopy. The association of these constituents of the elastic matrix with other components of the extracellular matrix was also studied, using several additional antibodies. Our results reveal the transient presence of an elastin-rich scaffold of extracellular matrix fibrillar material in association with the establishment of the cartilaginous skeleton of the leg bud. The scaffold consisted of elastin-positive fibers extending from the ectodermal surface of the limb to the central cartilage-forming regions and between adjacent cartilages. Fibrillin immunolabeling was negative in this fibrillar scaffold while other components of the extracellular matrix including: tenascin, laminin and collagens type I, type III and type VI; appeared codistributed with elastin in some regions of the scaffold. Progressive changes in the spatial pattern of distribution of the elastin-positive scaffold were detected in explant cultures in which one expects a modification in the mechanical stresses of the tissues related to growth. A scaffold of elastin comparable to that found in vivo was also observed in high-density micromass cultures of isolated limb mesodermal cells. In this case the elastic fibers are observed filling the spaces located between the cartilaginous nodules. The fibers become reoriented and attach to the ectodermal basal surface when an ectodermal fragment is located at the top of the growing micromass. Our results suggest that the formation of the cartilaginous skeleton of the limb involves the segregation of the undifferentiated limb mesenchyme into chondrogenic and elastogenic cell lineages. Further, a role for the elastic fiber scaffold in coordinating the size and the spatial location of the cartilaginous skeletal elements within the limb bud is also suggested from our observations.

Animals↗

PubMed1997

Golgi membrane skeleton: identification, localization and oligomerization of a 195 kDa ankyrin isoform associated with the Golgi complex.

To extend our finding of a Golgi-localized form of the membrane skeleton protein spectrin, we have identified an isoform of ankyrin that associates at steady state with the Golgi complex. Immuno-light and -electron microscopy show that this ankyrin isoform localizes to the perinuclear cytoplasm on tubular vesicular structures that co-stain with Golgi marker proteins. An antiserum raised against erythrocyte ankyrin, which was used to identify the Golgi ankyrin, recognized three prominent polypeptides of 220, 213 and 195 kDa in MDCK cells. Affinity purification of this antiserum against each of these MDCK cell ankyrins revealed that only an antibody specific for the 195 kDa form retained the ability to stain the Golgi complex; affinity purified antibody preparations specific for both the 220 and 213 kDa forms stained punctate and reticular cytoplasmic structures distinct from the Golgi complex. Antibody specific for the 195 kDa ankyrin did not recognize a recently identified 119 kDa ankyrin that is also localized to the Golgi. The 195 kDa Golgi ankyrin binds purified erythrocyte spectrin, and rapidly co-sediments with Golgi beta-spectrin during brief, low speed centrifugation of Triton X-100 extracts of MDCK cells. Golgi ankyrin and beta-spectrin are retained on tubular vesicular 'Golgi ghosts' following extraction of cultured cells with Triton X-100. Significantly, Golgi ghost tubules containing ankyrin/spectrin are co-linear with individual microtubules, suggesting a role for both Golgi membrane skeleton and microtubules in spatial localization of the Golgi. Golgi ankyrin dissociates from Golgi membranes during mitosis and in cells treated with brefeldin A, indicating that Golgi ankyrin has a dynamic assembly state similar to that of Golgi spectrin and other Golgi membrane coat proteins.

Animals↗

PubMed1997

Polarisation-dependent association of plectin with desmoplakin and the lateral submembrane skeleton in MDCK cells.

The intermediate filament-binding protein plectin and cytokeratin were localised at the cellular periphery of fully polarised Madin-Darby canine kidney (MDCK) cells, whereas vimentin was primarily found in a perinuclear network. Confocal and immunoelectron microscopy revealed that plectin was restricted to areas underlying the lateral plasma membrane. It colocalised with fodrin, a component of the submembrane skeleton, and was closely associated with desmosomal plaque structures. Biochemically, plectin was shown to interact directly with immunoprecipitated desmoplakin in vitro. Upon loss of cell polarity in low calcium medium, plectin redistributed to a cytoplasmic vimentin- and cytokeratin-related network, clearly distinct from diffusely distributed fodrin and internalised desmoplakin structures. The structural reorganisation of plectin was also reflected by an increased solubility of the protein in Triton X-100/high salt, and a decrease in its half-life from approximately 20 to approximately 5 hours. Furthermore, unlike cytokeratins and vimentin, desmoplakin and fodrin did not associate with plectin attached to magnetic beads in cell lysates of unpolarised cells, while all proteins formed a stable complex in polarised cells. Altogether, these data indicate that plectin is involved in the anchorage of intermediate filaments to desmosomes and to the submembrane skeleton in polarised MDCK cells.

Animals↗

PubMed1988

The structure of the macrophage actin skeleton.

The actin skeleton of the macrophage consists of a three-dimensional network of actin filaments and associated proteins. The organization of this multiprotein structure is regulated at several levels in cells. Receptor stimulation induces a massive actin polymerization at the cell cortex, changes in cell shape and active cellular movements. Gelsolin may have a pivotal role in restructuring the actin skeleton in response to agonist stimulation, as the activity of this potent actin-modulating protein is regulated by both Ca2+ and polyphosphoinositides. Micromolar concentrations of Ca2+ activate gelsolin to bind to the sides of actin filaments, sever, and cap the filament end. Polyphosphoinositides, in particular PIP and PIP2, release gelsolin from the filament ends. A structure-function analysis of gelsolin indicates that its N-terminal half is primarily responsible for severing actin filaments, and elucidates mechanisms by which Ca2+ and phospholipid may regulate gelsolin functions. The ultrastructure of actin filaments in the macrophage cortical cytoplasm is regulated, to a large extent, by the actin cross-linking protein, actin-binding protein (ABP) which defines filament orthogonality.

Actins↗

PubMed1987

Regional differentiation of the membrane skeleton in Tetrahymena.

Antisera have been raised in rabbits against three high molecular weight proteins that are present in Triton X-100-insoluble residues of Tetrahymena pyriformis GL cells. These proteins, called A, B and C, have apparent molecular weights of 235, 135 and 125 (X 10(3)), respectively, in SDS-polyacrylamide gels. The antisera obtained are specific for these proteins, as shown by immunoblotting. Immunolocalization studies are reported that suggest that these proteins are present throughout the epiplasmic layer beneath the cell surface (membrane skeleton). Images obtained with the fluorescence microscope, however, suggest that the membrane skeleton is modified in discrete zones: (1) around somatic basal bodies, (2) within the oral apparatus, (3) in the cytoproct, (4) in contractile vacuole pores, (5) in the fission zone in late division, and (6) at the mating junction in conjugating cells. These regions may represent areas of increased rigidity at the cell surface. The transition from pliable to rigid epiplasm in spatially delimited areas is apparently a recurring theme in cortical morphogenesis in Tetrahymena. Together, the two types of epiplasm probably allow for extensive changes in cell shape while preserving essential relationships between structural elements within the cortex.

Animals↗

PubMed2000

Alpha-glucosidase inhibitors with a phthalimide skeleton: structure-activity relationship study.

Alpha-glucosidase inhibitors with a phthalimide skeleton were prepared. Structure-activity relationship studies indicated a critical role for the hydrophobicity of the substituent at the nitrogen atom of the phthalimide skeleton. Introduction of electron-withdrawing groups, including a nitro group and chlorine, influenced the activity. Optimization studies led us to design 4,5,6,7-tetrachloro-N-phenylphthalimide (CPOP) and its N-phenylalkyl derivatives. CP0P and 4,5,6,7-tetrachloro-N-(4-phenylbutyl)phthalimide (CP4P) proved to be more potent alpha-glucosidase inhibitors than the known inhibitor 1-deoxynojirimycin.

Alkylation↗

PubMed2003

3D-imaging of the facial skeleton with an isocentric mobile C-arm system (Siremobil Iso-C3D).

OBJECTIVES: The purpose of this study was to compare three-dimensional (3D) imaging of the facial skeleton using an isocentric mobile C-arm system vs CT. METHODS: A dried human skull was scanned using a Siremobil Iso-C3D and a multi-detector CT (SOMATOM Volume Zoom; Siemens Medical Solutions, Erlangen, Germany) to compare reconstructed data sets. For each group of scans a standard protocol and a high resolution protocol were used. Image quality was analysed using six anatomical and six virtual structures in the primary reconstructed axial images of both data sets of the Siremobil Iso-C3D compared with CT. A receiver operating characteristic (ROC) study was performed with six examiners. RESULTS: The original categorical response data revealed no significant differences in sensitivity and specificity (P < 0.05). However, image quality of the reconstructed images of the Siremobil Iso-C3D was inferior to the CT images, with metal artefacts having a more prominent negative effect. CONCLUSIONS: The Siremobil Iso-C3D produces 3D images of the facial skeleton suitable for imaging osseous structures. No significant differences were found in sensitivity or specificity between the two methods. Metal objects degrade the image from the Iso-C method to a greater extent than those from CT.

Artifacts↗

PubMed1978

Induction of testicular growth and sexual activity in rams by a 'skeleton' short-day photoperiod.

Eight adult rams were housed in 16L:8D for 16 weeks and then exposed to short days (8L:16D) or 'skeleton' short days (11L:1D:5L:7D) for 16 weeks before being returned to long days. The 'skeleton' treatment promoted testicular development and regression in a way similar to that occurring in 8L:16D, indicating that a change in the total quantity of light is not a prerequisite for the photoperiodic response in the ram.

Animals↗

PubMed1985

Twenty-four-hour profiles of prolactin and testosterone in ram lambs exposed to skeleton photoperiods consisting of various light pulses.

Individual groups of 6 ram lambs were housed within a controlled environment and exposed to one of 6 photoperiod schedules. Groups I and II received 8 (short day) or 16 (long day) h of continuous light, respectively; Groups III, IV and V were exposed to asymmetrical skeleton photoperiods consisting of a main light period of 7 h followed 9 h later by a light pulse of 1 h, 15 min or 1 min duration, respectively, and Group VI was exposed to a symmetrical skeleton photoperiod consisting of two 1-h light pulses positioned 16 h apart. After 4 weeks of treatment serum concentrations of prolactin and testosterone were measured over 24 h. Long-day responses characteristic of the 16L:8D photoperiod (i.e. elevated prolactin and reduced testosterone) were obtained in each of the asymmetric light-pulse treatment groups, but whereas prolactin was elevated over the full 24 h in lambs exposed to 16L:8D, two prominent nocturnal prolactin releases were largely responsible for the high 24-h mean prolactin values in Groups III, IV and V. Reduced serum testosterone in these same groups could not be attributed to a diurnal pattern of secretion but was associated with an overall decrease in testosterone pulse frequency. Prolactin and testosterone levels in Group IV were intermediate between those observed in lambs exposed to 8 or 16 h of light. In summary, light pulses of short duration (1 min) positioned at 17 h after dawn can produce endocrine changes in lambs similar to those observed in lambs exposed to 16 h of continuous light.

Animals↗

PubMed2005

The technical aspect of the gastroepiploic artery graft skeletonization with the harmonic scalpel: the samurai technique.

A novel skeletonization technique using the scissors-type harmonic scalpel (Ethicon Endo-Surgery, Cincinnati, OH, USA) is presented. This "samurai technique," which uses the harmonic scalpel by frequently turning over the scissors, facilitates the handling of the gastroepiploic artery, enlarges the caliber size, and allows easy skeletonization without any vessel injury.

Coronary Artery Bypass↗

PubMed1982

Photoperiodism in quail: testicular growth and maintenance under skeleton photoperiods.

Testicular growth was induced in quail which were exposed to a skeleton photoperiod that included a pulse of light given during the dark period (night-interruption). The minimum duration of the pulse inducing testicular growth was 3.75 min per day. Longer pulses induced greater rates of growth, and of LH and FSH secretion; maximum rates occurred with a night-interruption of 60 min. Pulses even shorter than 3.75 min maintained testicular function in previously photostimulated quail. A night-interruption of 14s maintained full testicular size and hormone secretion in four out of six quail, and with 56s no regression whatsoever occurred. The rate of testicular growth was largely independent of the duration of the main light period used in the skeleton treatment. The light intensity within the night-interruption also affected the degree of testicular development and gonadotrophin secretion.

Animals↗

PubMed1996

Collagen fibrillar skeleton in pregnant rabbit endometrium at term: a SEM study after NaOH maceration.

This paper describes the spatial organization of the collagen fibrillar skeleton in pregnant rabbit endometrium at term, employing an alkali/low temperature/maceration technique followed by scanning electron microscopic (SEM) observations. Parallel light microscopic (LM) and transmission electron microscopic (TEM) investigations were made to identify the location and possible changes in the endometrial collagen network. Two different types of NaOH maceration were applied, demonstrating separately: 1) the collagen structures (2N-NaOH maceration removes the cells and basal laminae); and 2) the cellular elements (6N-NaOH maceration removes the collagen fibrils). After 2N-NaOH maceration, the collagen network of the endometrium is seen in a superficial compartment around the glands and a deep compartment situated near the endometrial-myometrial junction. Significant changes are observed only in the superficial compartment. The luminal mucosal surface is characterized by numerous thin projections reducing the uterine cavity which, as a consequence, further appears very irregular and highly convoluted. The subepithelial collagen network is composed of densely packed fibrils with a woven course. It contains many tubular or channel-like invaginations (100-150 microns in width and 200-300 microns in length) where endometrial glands are located. These invaginations, corresponding to the glandular impressions, are extremely dilated, enlarged and variable in shape. The collagen fibrils are arranged concentrically around the glandular orifices without forming bundles. At the bottom of the spaces between the mucosal projections, small fenestrations (4-8 microns in diameter each) are present. They form small groups of about 10-20 in number and are due to the endometrial blood capillaries. The deep compartment of the endometrial collagen network is little altered, preserving its general lamellar arrangement. The changes in the endometrial collagen skeleton are due to a variety of complex mechanical and hormonal stimuli affecting the uterus during pregnancy. These may be significant for correct implantation, placentation and delivery.

Animals↗

PubMed1984

Reduction of absorbed doses in radiography of the facial skeleton.

Radiation absorbed doses from radiography of the paranasal sinuses and the facial skeleton were measured with thermoluminescent dosimeters (TLD) on a phantom head using high-sensitivity screens in an Orbix stand. The entrance doses to the skin of the head ranged from 0.31 to 2.9 mGy per exposure. The absorbed dose from a full series of sinus exposures averaged 0.33 mGy for the oral mucous membrane, 0.33 mGy for the maxillary sinus mucous membrane, 0.11 mGy for the parotid gland, 0.15 mGy for the submandibular gland, 0.61 mGy for the eye lens, and 0.75 mGy for the thyroid gland region. A leaded soft collar adapted to the thyroid region reduced the thyroid doses by more than one order of magnitude, but also reduced the image field. The mean energy imparted from a full series of paranasal sinus projections was 4.8 mJ and from a total series of the facial skeleton, 7.9 mJ.

Facial Bones↗

PubMed1990

Metastases from malignant melanoma to the axial skeleton: a CT study of frequency and appearance.

Radiologic detection of bone lesions from malignant melanoma is reported to be uncommon or infrequent. To ascertain the characteristics and frequency of detection of melanoma metastases to the axial skeleton by CT, we retrospectively reviewed 464 body CT studies of 125 consecutive melanoma patients for presence, appearance, and site of skeletal metastases. Results were correlated with patient's age, sex, clinical course, and both the Clark and Breslow classifications of the primary lesion. Of 98 patients with metastatic disease evident on their CT studies, 17 (17%) had bony metastases; two (12%) of these 17 patients had skeletal lesions as the only CT evidence of metastatic disease. Metastatic bony lesions were predominantly osteolytic, slightly expansile, and commonly located in the spine. Associated soft-tissue masses were frequent, but periosteal reaction and identifiable tumor matrix were not seen. Skeletal metastases were found only in those patients with thick or intermediate primary melanoma (Breslow) classified as Clark level III or greater, and the CT demonstration of osseous metastases was a poor prognostic sign. The data suggest that CT detection of skeletal melanoma metastases is not uncommon. When CT is performed to evaluate for metastatic melanoma, the axial skeleton should be carefully examined, especially in those patients with more advanced primary lesions.

Adult↗

PubMed1990

Facial skeleton remodeling due to temporomandibular joint degeneration: an imaging study of 100 patients.

One hundred patients with recently acquired, externally visible mandibular deformity and no history of previous extraarticular mandible fracture were selected for retrospective analysis. All had been investigated clinically and with radiography, tomography, and high-field surface-coil MR imaging to determine the presence or absence and extent of temporomandibular joint degeneration. Temporomandibular joint degeneration was found in either one or both joints of each patient studied. Chin deviation was always toward the smaller mandibular condyle or more diseased joint, and many patients either complained of or exhibited malocclusion, often manifested by unstable or fluctuating occlusion disturbances. Three radiologically distinct forms of degenerative vs adaptive osteocartilaginous processes--(1) osteoarthritis, (2) avascular necrosis, and (3) regressive remodeling--involving the mandibular condyle and temporal bone were identified in joints most often exhibiting meniscus derangement. Osteoarthritis and avascular necrosis of the mandibular condyle and temporal bone were generally associated with pain, mechanical joint symptoms, and occlusion disturbances. Regressive remodeling was less frequently associated with occlusion disturbances, despite remodeling of the facial skeleton, and appears to result from regional osteoporosis. Forty patients (52 joints) underwent open arthroplasty procedures, including either meniscectomy or microsurgical meniscus repair, at which time major radiologic diagnoses were confirmed. Surgical and pathologic findings included meniscus displacement, disk degeneration, synovitis, joint effusion, articular cartilage erosion, cartilage healing/fibrosis, cartilage hypertrophy, osseous sclerosis, osteophyte formation, osteochondritis dissecans, localized or extensive avascular necrosis, and decreased mandibular condyle mass and vertical dimension. We conclude that temporomandibular joint degeneration is the principal cause of both acquired facial skeleton remodeling and unstable occlusion in patients with intact dentition and without previous mandible fracture.

Adolescent↗

PubMed2001

Shaping of colony elements in Laomedea flexuosa Hinks (Hydrozoa, Thecaphora) includes a temporal and spatial control of skeleton hardening.

The colonies of thecate hydroids are covered with a chitinous tubelike outer skeleton, the perisarc. The perisarc shows a species-specific pattern of annuli, curvatures, and smooth parts. This pattern is exclusively formed at the growing tips at which the soft perisarc material is expelled by the underlying epithelium. Just behind the apex of the tip, this material hardens. We treated growing cultures of Laomedea flexuosa with substances we suspected would interfere with the hardening of the perisarc (L-cysteine, phenylthiourea) and those we expected would stimulate it (dopamine, N-acetyldopamine). We found that the former caused a widening of and the latter a reduction in the diameter of the perisarc tube. At the same time, the length of the structure elements changed so that the volume remained almost constant. We propose that normal development involves a spatial and temporal regulation of the hardening process. When the hardening occurs close to the apex, the diameter of the tube decreases. When it takes place farther from the apex, the innate tendency of the tip tissue to expand causes a widening of the skeleton tube. An oscillation of the position at which hardening takes place causes the formation of annuli.

Animals↗

PubMed2006

Protein profiling of sickle cell versus control RBC core membrane skeletons by ICAT technology and tandem mass spectrometry.

A proteomic approach using a cleavable ICAT reagent and nano-LC ESI tandem mass spectrometry was used to perform protein profiling of core RBC membrane skeleton proteins between sickle cell patients (SS) and controls (AA), and determine the efficacy of this technology. The data was validated through Peptide/Protein Prophet and protein ratios were calculated through ASAPratio. Through an ANOVA test, it was determined that there is no significant difference in the mean ratios from control populations (AA1/AA2) and sickle cell versus control populations (AA/SS). The mean ratios were not significantly different from 1.0 in either comparison for the core skeleton proteins (alpha spectrin, beta spectrin, band 4.1 and actin). On the natural-log scale, the variation (standard deviation) of the method was determined to be 14.1% and the variation contributed by the samples was 13.8% which together give a total variation of 19.7% in the ratios.

Anemia, Sickle Cell↗

PubMed1986

Daily rhythm of cortisol, and evidence for a photo-inducible phase for prolactin secretion in nonpregnant mares housed under non-interrupted and skeleton photoperiods.

Studies were conducted in anestrous mares to characterize daily rhythms of cortisol in non-interrupted [ambient and 16 h light (L): 8 h dark (D)] and skeleton (10L:4D:2L:8D, 10L:6D:2L:6D and 10L:8D:2L:4D) photoperiods, and to determine if there exists a photosensitive phase for the secretion of prolactin. Neither peak or nadir concentrations of cortisol, nor the time of peak or nadir concentrations differed among photoperiod treatments. Highest concentrations (66 +/- 4.4 ng/ml, mean +/- SE) occurred between 0700 and 0900, whereas lowest concentrations (31 +/- 3.6 ng/ml) were found from 1900 to 2300. Mean daily concentrations of serum prolactin were significantly higher in mares housed under the 16L:8D and the 10L:8D:2L:4D photoperiods as compared with the remaining photoperiod treatments, and were lowest in the ambient photoperiod treatment. The mean daily concentration of prolactin in February among photoperiod treatments was inversely related to the number of days (from December 1) to first seasonal ovulation (r = -.92, P = .027). The results were interpreted to: 1) suggest that mares in the 10L:8D:2L:4D skeleton photoperiod do not phase-shift to interpret the 2-h light pulse as the beginning of their subjective day; and 2) provide further evidence that the photo-inducible phase for both prolactin secretion and the stimulation of seasonal reproductive activity occurs 8 to 10 h following the onset of the dark period (scotophase).

Animals↗