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At least 955 records · Page 53Linked to original sources
PubMed1991

Subtypes of protein kinase C in isolated nerve growth cones: only type II is associated with the membrane skeleton from growth cones.

The growth cone particle (GCP) fraction was isolated from fetal and neonatal rat brains and the distribution of protein kinase C subtypes in the fraction was examined by using subtype-specific antibodies. The main subtype in the GCP fraction from fetal forebrain was type II, and type III was also present, but not type I. The pattern was not altered from embryonic day 17 to postnatal day 5. The membrane skeleton subfraction from the GCP fraction contained type II, but far less amount of type III. Our results suggest that type II and type III may be closely related to the functions of growth cones but that they appear to be associated with distinct signal transduction processes.

Animals↗
PubMed1992

Papulacandins and chaetiacandin: a stereoselective route to their basic skeleton by a palladium-mediated arylation of 4,6-O-benzylidene-3-O-tert- butyldimethylsilyl-l-tributyl-stannyl-D-glucal.

Palladium(0)-catalysed coupling of 1,5-anhydro-4,6-O-benzylidene-3-O-tert- butyldimethylsilyl-2-deoxy-1-tributylstannyl-D-arabino-hex-1-eni tol (7) with 3,5-dibenzyloxy-2-bromobenzyl alcohol gave 1,1(2)-anhydro-4,6-O-benzylidene-3-O-tert-butyldimethylsilyl-2-deoxy-1-( 4,6- dibenzyloxy-2-hydroxymethyl-phenyl)-alpha-D-arabino-hexopyranos e (13). The same reaction buffered by sodium carbonate provided 1,5-anhydro-4,6- O-benzylidene-3-O-tert-butyldimethylsilyl-2-deoxy-1-(4,6-dibenzyloxy+ ++-2- hydroxymethyl-phenyl)-D-arabino-hex-1-enitol (11). Stereoselective oxidative spiroacetalisation of 11 provided 1,1(2)- anhydro-4,6-O-benzylidene-3-O-tert-butyldimethylsilyl-1-(4,6-dibenzyl oxy-2- hydroxymethyl-phenyl)-alpha-D-glucopyranose (15), the basic tricyclic structure of papulacandins. In a model study, 15 was converted in three steps into 1,1(2)-anhydro-1-(4,6-dihydroxy-2-hydroxymethylphenyl)-3-O- octadecanoyl-alpha-D-glucopyranose (24), a structural analogue of papulacandin D. Moreover, stereoselective hydroboration-oxidation of 11 furnished 2-(4,6-O-benzylidene-3-O-tert-butyldimethylsilyl-beta-D- glucopyranosyl)-3,5-dibenzyloxy-1-hydroxymethylbenzene (26), the structural skeleton of the chaetiacandin 3.

Aminoglycosides↗
PubMed1989

Transient expression of a chondroitin sulfate-related epitope during cartilage histomorphogenesis in the axial skeleton of fetal rats.

A monoclonal antibody (MC21C), raised in mouse in response to a mixture of bone proteins, was found to exhibit a unique reactivity toward native chondroitin sulfate chains. Indirect immunofluorescence and immunoperoxidase assays were performed on tissue sections at different stages of fetal rat development, in order to investigate the distribution of the MC21C epitope during cartilage morphogenesis and differentiation. This extracellular marker was present in the sclerotome and its distribution subsequently followed the segmentation pattern of the precartilaginous vertebral column. In addition, changes in the MC21C-immunostaining pattern strongly correlated with the initial growth of the vertebrae. In the axial skeleton (spinal column, basis cranii), the immunostaining by MC21C was maximum in precartilaginous condensations and then rapidly disappeared during the process of chondrification. Also, the perinotochordal matrix was intensely immunostained.

Alcian Blue↗
PubMed1985

Initiated complexes of RNA polymerase II are concentrated in the nuclear skeleton associated DNA.

Several preparations of nuclear matrices containing varying amounts of DNA were obtained from mouse plasmocytoma P3-X63-Ag8.653 cells and tested for the presence of RNA polymerase II activity. It has been demonstrated that about 25% of RNA polymerase II activity detected in the original nuclei can be recovered in isolated nuclear matrices. Only DNA-bound RNA polymerase II was found in the isolated matrices, while both free and DNA-bound RNA polymerase II activities were detected in the original nuclei. RNA polymerase II activity found in the isolated matrices did not depend on the portion of DNA recovered in the nuclear matrices in a large interval between 91 and 1.5% of DNA content in the original nuclei. The conclusion has been drawn that initiated RNA polymerase II molecules are non-randomly distributed along DNA loops. They are concentrated near the points of DNA attachment to the nuclear skeleton.

Animals↗
PubMed1987

Synthetic analogues of vitamin D3 with an oxygen atom in the side chain skeleton. A trial of the development of vitamin D compounds which exhibit potent differentiation-inducing activity without inducing hypercalcemia.

Four analogues of vitamin D3 with an oxygen atom in the side chain skeleton were synthesized to determine whether their differentiation-inducing activity could be separated structurally from their activity to induce hypercalcemia. The order of the in vitro potency to reduce nitroblue tetrazolium in human myeloid leukemia cells (HL-60) was 22-oxa-1 alpha, 25-(OH)2D3 greater than 1 alpha, 25-(OH)2D3 greater than 20-oxa-1 alpha, 25-(OH)2D3 not equal to 22-oxa-1 alpha-(OH)D3 greater than 1 alpha-(OH)D3 greater than 20-oxa-1 alpha-(OH)D3. 22-Oxa-1 alpha, 25-(OH)2D3 was also about 10-times more potent than 1 alpha, 25-(OH)2D3 in suppressing proliferation and inducing differentiation of mouse myelomonocytic leukemia cells (WEHI-3), but the former was much weaker than the latter in inducing the release of 45Ca from prelabeled fetal mouse calvaria. These results suggest that the differentiation-inducing activity of vitamin D compounds can be separated structurally from their activity to induce hypercalcemia.

Animals↗
PubMed1993

Evidence for a membrane skeleton in higher plants. A spectrin-like polypeptide co-isolates with rice root plasma membranes.

A fraction enriched in plasma membranes was isolated from rice roots by differential centrifugation and aqueous polymer two-phase partitioning. Analysis of the fraction by SDS-PAGE showed the presence of several low mobility polypeptides (M(r) > 100 kDa). One of these polypeptides (M(r) approximately 230 kDa) was specifically recognized by polyclonal antibodies to human erythrocyte spectrin. This finding suggests that a higher plant spectrin-based membrane skeleton may be preserved and studied using high-purity plasma membrane fractions obtained by aqueous polymer two-phase partitioning.

Adenosine Triphosphatases↗
PubMed1995

Fractures of the facial skeleton in children.

Fractures of the facial skeleton in children are uncommon. This study presents the results of 139 children who sustained a total of 161 such fractures and were admitted to the Royal Hospital for Sick Children, Edinburgh, between January 1983 and December 1992. The male to female ratio was 3:1 and the highest incidence was at age 10 years. Analysis of fracture patterns showed that despite differences in anatomy, the fracture patterns were similar to those occurring in adults, but the relative proportion of each fracture type was different in children. Nasal fractures occurred most frequently (54 per cent), mandibular fractures constituted 30 per cent, and middle third fractures only 16 per cent. Falls, sporting injuries and road traffic accidents (RTA) were the major causes of these injuries. Injuries sustained in RTA were most likely to have involved cyclists or pedestrians in contrast to earlier series which have identified these injuries mainly among car passengers. No deaths were recorded and most patients made a complete recovery, although a few required secondary surgery for complications. This taken in conjunction with the findings of both high numbers of associated injuries, and increased severity commonly occurring in both mandibular and middle third injuries leads to the suggestion that these should be treated in centres where multidisciplinary management can easily be coordinated.

Accidental Falls↗
PubMed1993

Determining the movements of the skeleton using well-configured markers.

The problem of determining skeletal movements in three dimensions by using a number of landmarks is treated. We present a method that determines the motion of a rigid body by using the positions of the landmarks in least-squares sense. The method uses the singular value decomposition of a matrix derived from the positions of the landmarks. We show how one can use this method to express movement of skeleton segments relative to each other. As many others have pointed out, the movement can be very ill determined if the landmarks are badly configured. We present a condition number for the problem with good geometrical properties. The condition number depends on the configuration of the landmarks and indicates how to distribute the landmarks in a suitable way.

Algorithms↗
PubMed1989

Disturbed endochondral ossification in the axial skeleton of young broiler fowls.

Physeal lesions have been studied in thoracic vertebrae (T3, T4 and T5) of 51 broiler fowls between 28 and 53 days old. Vascular perfusion studies performed on 10 birds confirmed that the cartilaginous epiphyses of T3, T4 and T5 were essentially avascular and thus differ from those of the major long bones. Findings confirm the observation that a number of morphologically distinct lesions of osteochondrosis occur in broiler fowls and that, when physeal clefts can be implicated in their aetiology, the term "osteochondrosis" is inappropriate. Although the location of clefts often differs in long bone and vertebral physes, when metaphyseal vessels are disrupted, the end-result on endochondral ossification is the same in both the axial and appendicular skeleton. Other lesions were observed both independently and in association with osteochondrosis. Such lesions include necrotic seams devoid of haemorrhage, acellular foci and chondrolysis, all of which were most frequently observed in the same vertebral end-plates. Because osteochondrosis was also most common in the same vertebral end-plates, a common aetiology is suggested. Surface regressive changes were common in the articular cartilage of T3, T4 and T5, and it is noteworthy that such changes, although common in older birds, are present in birds so young.

Animals↗
PubMed1980

The pattern of fractures of the facial skeleton in Kaduna, Nigeria. A survey of 1,447 cases.

A survey of 1,447 Nigerian patients with fractures of the facial skeleton is presented. The frequency and etiology of the fractures are described. Patients mainly affected were in the third decade of life. The male:female ratio is strikingly high, and the site distributions of the fractures are recorded and compared with those of other series. The cause of delay in reporting for treatment is examined, and the subsequent sequalae are outlined. Life-endangering injuries occurred in association with facial fractures. The necessity for teamwork between surgical specialists is emphasized. All fractures were treated by simple methods of fixation.

Accidents, Traffic↗
PubMed1986

Effect of skeleton photoperiod and food availability on the circadian pattern of feeding and drinking in rats.

Feeding and drinking behavior were measured in rats maintained under a 12:12 light-dark (LD) cycle or skeleton photoperiod (SPP). Feeding and drinking were closely associated during the normal LD cycle but under SPP conditions an increased feeding activity during the subjective day was not accompanied by an equivalent increment of water intake. This indicates a stronger coupling of drinking to the subjective night. A restriction of food availability to the subjective light phase did not cause an accompanying complete shift in drinking behavior. These results suggest that drinking is largely dependent on the influence of a circadian oscillator and this association is not disrupted by changes in feeding schedule. A change in food access to the subjective light phase caused partial but not permanent desynchronization between feeding and drinking behavior. Synchrony was reestablished within one day once food was available ad lib. Complete return to the original feeding and drinking patterning took 3 days. It is suggested that separate slave oscillators controlling feeding and drinking are governed by a hypothesized "master" circadian oscillator which remains definitely entrained to the original rhythm by the light pulses of the SPP condition.

Animals↗
PubMed1990

Feeding ecology of the stone and pine marten revealed by element analysis of their skeletons.

Feeding habits of free-ranging martens (Martes martes and Martes foina) are evaluated by means of trace element and stable carbon isotope analyses of their skeletons. This investigation was carried out as an inter-disciplinary project of both wildlife biology and physical anthropology. As a result, data are obtained on the feeding ecology of the two species; in addition, a baseline is provided for dietary reconstruction of past human populations. Both species of martens are omnivorous feeders, M. martes being slightly more carnivorous than M. foina. Diversity of dietary intake with respect to plant food and animal protein is only one-third of the maximum divergence between strict herbivores and carnivores.

Animals↗
PubMed1994

Dietary intake evaluation and dosimetric modelling for the Techa River residents based on in vivo measurements of strontium-90 in teeth and skeleton.

Explanations are given for the models and algorithms that are utilised to reconstruct the doses due to the incorporation of 90Sr in the inhabitants of the Techa riverside villages. A model for the 90Sr accumulation and excretion in the tooth enamel is employed to derive the relative intakes of 90Sr in the years 1950-1959. The measurements of beta-ray activity on the surface of the front teeth of persons born between 1940-1959 are used to derive the relative intakes in different calendar years and the transfer functions to the tooth enamel as a function of age. This derivation is based on a non-linear optimisation algorithm, to fit the observed average count rates for different birth cohorts in a village. The data for the village of Muslyumovo are used as the reference data set. Absolute values of the strontium intake are derived from the relative values by a fit to the measurements of the 90Sr body burdens that were performed after 1974. A model has been developed for the age-dependent metabolism of strontium in the skeleton. The computations in terms of this model are in reliable agreement with experimental data on strontium in man.

Adult↗
PubMed1988

Antisense RNA inhibits expression of membrane skeleton protein 4.1 during embryonic development of Xenopus.

Plasmids expressing partial-length sense or antisense protein 4.1 RNA were microinjected into fertilized Xenopus eggs. Nuclease protection assays reveal that antisense protein 4.1 RNA lead to the specific loss of endogenous protein 4.1 transcripts after midblastula transition, with no effect on the levels of three unrelated transcripts. As a control, we show that this dramatic loss of endogenous protein 4.1 transcripts is blocked when fertilized eggs receive a second injection of plasmids that express partial-length sense protein 4.1 RNA. Immunocytochemistry of tadpole embryos with antibodies monospecific for protein 4.1 demonstrates that the antisense protein 4.1 RNA blocks the normal expression of protein 4.1 in embryos and interferes with the normal interdigitation of the photoreceptor outer segments with the pigment epithelium layer in the retina. These data suggest that reduced expression of a single membrane skeleton protein is sufficient to perturb normal cellular interactions of the retina.

Amino Acid Sequence↗
PubMed1991

Use of adjuvant containing mycobacterial cell-wall skeleton, monophosphoryl lipid A, and squalane in malaria circumsporozoite protein vaccine.

Human immune responses to modern synthetic and recombinant peptide vaccines administered with the standard adjuvant, aluminum hydroxide, tend to be poor, hence the search for better adjuvants. Antibody responses to a Plasmodium falciparum circumsporozoite (CS) protein vaccine, R32NS1(81), administered with an adjuvant containing cell-wall skeleton of mycobacteria and monophosphoryl lipid A in squalane (MPL/CWS) have been compared to responses to the same immunogen administered with aluminum hydroxide. 2 weeks after the third dose the following indices were greater in the 5 patients who received MPL/CWS than in controls (p less than 0.05): the geometric mean concentration (2.0 vs 25.4 microgram/ml) and avidity index of antibodies to the P falciparum CS protein by ELISA, the geometric mean titre to P falciparum sporozoites by IFAT (1/115 vs 1/1600), and the geometric mean inhibition of sporozoite invasion of hepatoma cells in vitro (37.6 vs 90.3%). For R32NS1(81) MPL/CWS is superior to aluminum hydroxide as an adjuvant, and the data support the evaluation of this complex as an adjuvant for other vaccines.

Adjuvants, Immunologic↗
PubMed1988

Three-dimensional model of the human craniofacial skeleton: method and preliminary results using finite element analysis.

The purpose of this study was to develop a three-dimensional finite element model of the craniofacial skeleton using a dry human skull. The model consisted of 2918 nodes and 1776 solid elements, and was used to investigate the biomechanical effect of a distally directed orthopaedic force on the craniofacial complex. The force was applied at the level of the maxillary first molar. The results indicated that in response to the force system applied: the nasomaxillary complex displaces in a backward and downward direction and rotates in clockwise sense; the nasomaxillary complex, including the zygomatic bone, experiences high stress levels in comparison with those at the remaining bones; the stress distribution in the maxillary basal bone area is relatively uniform; and the stress distribution across the opposing surface of the bony margins of the sutures is non-uniform.

Biomechanical Phenomena↗
PubMed1992

The combined application of organic sulphur and isotope geochemistry to assess multiple sources of palaeobiochemicals with identical carbon skeletons.

Five immature sediments from a Messinian evaporitic basin, representing one evaporitic cycle, were studied using molecular organic sulphur and isotope geochemistry. It is shown that a specific carbon skeleton which is present in different "modes of occurrence" ("free" hydrocarbon, alkylthiophene, alkylthiolane, alkyldithiane, alkylthiane, and sulphur-bound in macromolecules) may have different biosynthetic precursors which are possibly derived from different biota. It is demonstrated that the mode of occurrence and the carbon isotopic composition of a sedimentary lipid can be used to "reconstruct" its biochemical precursor. This novel approach of recognition of the suite of palaeobiochemicals present during the time of deposition allows for identification of the biological sources with an unprecedented specificity.

Carbon↗
PubMed1995

Molecular indicators for palaeoenvironmental change in a Messinian evaporitic sequence (Vena del Gesso, Italy). II: High-resolution variations in abundances and 13C contents of free and sulphur-bound carbon skeletons in a single marl bed.

The extractable organic matter of 10 immature samples from a marl bed of one evaporitic cycle of the Vena del Gesso sediments (Gessoso-solfifera Fm., Messinian, Italy) was analyzed quantitatively for free hydrocarbons and organic sulphur compounds. Nickel boride was used as a desulphurizing agent to recover sulphur-bound lipids from the polar and asphaltene fractions. Carbon isotopic compositions (delta vs PDB) of free hydrocarbons and of S-bound hydrocarbons were also measured. Relationships between these carbon skeletons, precursor biolipids, and the organisms producing them could then be examined. Concentrations of S-bound lipids and free hydrocarbons and their delta values were plotted vs depth in the marl bed and the profiles were interpreted in terms of variations in source organisms, 13 C contents of the carbon source, and environmentally induced changes in isotopic fractionation. The overall range of delta values measured was 24.7%, from -11.6% for a component derived from green sulphur bacteria (Chlorobiaceae) to -36.3% for a lipid derived from purple sulphur bacteria (Chromatiaceae). Deconvolution of mixtures of components deriving from multiple sources (green and purple sulphur bacteria, coccolithophorids, microalgae and higher plants) was sometimes possible because both quantitative and isotopic data were available and because either the free or S-bound pool sometimes appeared to contain material from a single source. Several free n-alkanes and S-bound lipids appeared to be specific products of upper-water-column primary producers (i.e. algae and cyanobacteria). Others derived from anaerobic photoautotrophs and from heterotrophic protozoa (ciliates), which apparently fed partly on Chlorobiaceae. Four groups of n-alkanes produced by algae or cyanobacteria were also recognized based on systematic variations of abundance and isotopic composition with depth. For hydrocarbons probably derived from microalgae, isotopic variations are well correlated with those of total organic carbon. A resistant aliphatic biomacromolecule produced by microalgae is, therefore, probably an important component of the kerogen. These variations reflect changes in the depositional environment and early diagenetic transformations. Changes in the concentrations of S-bound lipids induced by variations in conditions favourable for sulphurization were discriminated from those related to variations in primary producer assemblages. The water column of the lagoonal basin was stratified and photic zone anoxia occurred during the early and middle stages of marl deposition. During the last stage of the marl deposition the stratification collapsed due to a significant shallowing of the water column. Contributions from anaerobic photoautotrophs were apparently associated with variations in depth of the chemocline.

Animals↗