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Results for “structural variation”

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At least 325 records · Page 18Linked to original sources
PubMed1999

Structural variation of the distal condyles of the third metacarpal and third metatarsal bones in the horse.

This study examined 3-dimensional (3D) distribution of sectors with contrasting density in the equine third metacarpal (McIII) and third metatarsal (MtIII) bones with a view to explaining the aetiology of distal condylar fractures. Macroradiography and computed tomographic (CT) imaging were used in the nondestructive study of bones obtained from horses, most of which were Thoroughbreds in race training. Distal condylar regions of McIII and MtIII were also studied in microradiographs of 100 microm thick mediolateral sections cut perpendicular to the dorsal and palmar/plantar articular surfaces. Qualitative and quantitative results from all methods used (radiography, CT and microradiographic stereology) demonstrated a densification (sclerosis) of subchondral bone located in the palmar/plantar regions of the medial and lateral condyles of both McIII and MtIII. Substantial density gradients between the denser condyles and the subchondral bone of the sagittal groove were shown to equate with anatomical differences in loading intensity during locomotion. It is hypothesised that such differences in bone density results in stress concentration at the palmar/plantar aspect of the condylar grooves, which may predispose to fracture.

Animals↗
PubMed1982

Effects of structural variations of non-ionic surfactants on micellar properties and solubilization: variation of oxyethylene content on properties of C22 monoethers.

Studies on erucyl alcohol ethoxylated with 40 and 47 units, and on behenyl alcohol ethoxylated with 33 and 43 units, gave values of 106, 101, 271, and 304 (all X 10(3)) for the micellar weight, 51,42,152, and 137 for the aggregation numbers, and 257,362,209, and 311 moles water mol-1 surfactant for the micellar hydration, respectively. Measurements of the solubilization of azobenzene, cortisone acetate, griseofulvin, sulphadiazine, phenylbutazone, betamethasone, tolbutamide, and menaphthone showed that the erucyl derivatives were better solubilizers than the behenyl compounds, and that solubilization increased as the polyoxyethylene chain was shortened; this change was more pronounced with the erucyl compounds.

Chemical Phenomena↗
PubMed1989

Effect of structural variations of non-ionic surfactants on micellar properties and solubilization: surfactants with semi-polar hydrophobes.

Novel non-ionic surfactants have been synthesized in which a polar group (either an ether or a keto group) has been introduced into the hydrocarbon chain of an octadecylpolyoxyethylene glycol monoether (C18En) with an oxyethylene chain length, n, of 17-18 units. Light scattering studies have indicated aggregation numbers for these semi-polar surfactants in aqueous solution of between 55-65% of that of an unsubstituted octadecylpolyoxyethylene glycol monoether, C18E22. The solubilizing capacities of the semi-polar surfactant micelles for test compounds which were mainly solubilized at the polyoxyethylene/core interface were lower than those of C18E22 whilst solubilizates which exhibited a reasonable degree of solubility in both the interface and the micellar core showed an increased solubilization.

Chemical Phenomena↗
PubMed1990

Effect of structural variations of non-ionic surfactants on surface properties: surfactants with semi-polar hydrophobes.

The surface properties of a series of non-ionic surfactants in which a polar group (either an ether or a keto group) has been introduced into a hydrocarbon chain of octadecylpolyoxyethylene glycol monoether (C18E17-19) have been investigated. Surface tension measurements indicated that the critical micelle concentrations for these semi-polar surfactants in aqueous solution were all significantly higher than those of C18E22, the corresponding unsubstituted octadecylpolyoxyethylene glycol monoether. The minimum areas per molecule of the semi-polar surfactants in the surface monolayer were all larger than the area obtained for C18E22, from which it was concluded that the hydrophobe, and not the polyoxyethylene chain was the main determinant of surface area.

Micelles↗
PubMed2003

Multiple origins of cultivated radishes as evidenced by a comparison of the structural variations in mitochondrial DNA of Raphanus.

Configurations of mitochondrial coxI and orfB gene regions were analysed by polymerase chain reaction (PCR) in three wild and one cultivated species of Raphanus. A total of 207 individual plants from 60 accessions were used. PCR with five combinations of primers identified five different amplification patterns both in wild and cultivated radishes. While the mitochondrial DNA (mtDNA) type of Ogura male-sterile cytoplasm was distinguishable from the normal type, the mtDNAs of normal radishes were further classified into four types. The variations were common to wild and cultivated radishes, although contrasting features were found depending on the region of cultivation. These results provide evidence that cultivated radishes have multiple origins from various wild plants of Raphanus.

Biological Evolution↗
PubMed2026

The Charcot-Marie-Tooth Neuropathy (CMTX3) Complex Structural Variation Causes Differential SOX3 Spatiotemporal Expression.

Charcot-Marie-Tooth (CMT) neuropathy is a clinically and genetically heterogeneous group of diseases characterized by the length-dependent axonal degeneration of peripheral nerves. We previously mapped a rare form of X-linked CMT, CMTX3, to a 5.7-Mb interval on chromosome Xq26.3-q27.1 and excluded the coding region of all known genes in the linkage interval for mutations. Whole genome sequencing subsequently identified a 78-kb region of chromosome 8q24.3 that had been duplicated and inserted into the CMTX3 locus between the genes HAPSTR2 and SOX3. The 78-kb insertion, which contains a partial transcript of ARHGAP39, fully segregated in families with CMTX3 and was absent in neurologically normal controls. To retain the CMTX3 insertion and investigate its consequences in appropriate neuronal tissue, we generated induced pluripotent stem cells (iPSCs) from CMTX3 fibroblasts. Using bulk RNA sequencing of patient-derived spinal motor neurons, ARHGAP39 was deemed nonpathogenic by excluding both the formation of novel fusion transcripts and dosage effects from the partial duplication. Subsequent NanoString expression analyses of candidate genes within the CMTX3 locus, across different stages of neuronal differentiation, identified spatiotemporal dysregulation of SOX3. NanoString showed reduced SOX3 expression in patient iPSCs. RNA sequencing detected SOX3 downregulation in CMTX3 neuroepithelial progenitor cells, which was further confirmed by quantitative proteomics. Given the early onset and relatively rapid progression of CMTX3, these data prioritise SOX3 as a leading candidate gene, consistent with its role as one of the earliest transcription factors expressed in the developing nervous system and a key regulator of neuronal fate.

Humans↗
PubMed1998

Dissociation of human chorionic gonadotropin into its free subunits is dependent on naturally occurring molecular structural variation, sample matrix and storage conditions.

Measurement of human chorionic gonadotrophin (hCG) is used in many areas of clinical medicine. Recent interest has focused on the stability of this molecule and its fragments during sample storage. In the body hCG is degraded and removed by specific metabolic processes which begin while the molecule is in the bloodstream. In particular, the receptor binding loop of the beta subunit is cut or 'nicked', initiating a catabolic cascade. Furthermore, the extent and nature of glycosylation is believed to have a significant influence on this process. In these studies we incubated seven glycoforms of hCG, each with different degrees of 'nicking', in phosphate-buffered saline, serum, defibrinated blood and urine from healthy non-pregnant women, under varying conditions. Degradation was expressed as the molar increase in free beta subunit. Under all conditions there was a steady dissociation of hCG over time, the process being more rapid at higher temperatures. 'Nicked' hCG dissociated more rapidly than did non-'nicked' hCG. Glycosylation reduced the rate of dissociation. Dissociation was most rapid in urine and buffer solutions, and slowest in serum and defibrinated blood.

Chorionic Gonadotropin↗
PubMed2005

Learning spatial orientation tasks in the radial-maze and structural variation in the hippocampus in inbred mice.

In the present paper we review a series of experiments showing that heritable variations in the size of the hippocampal intra- and infrapyramidal mossy fiber (IIPMF) terminal fields correlate with performance in spatial, but not non-spatial radial-maze tasks. Experimental manipulation of the size of this projection by means of early postnatal hyperthyroidism produces the effects predicted from the correlations obtained with inbred mouse strains. Although the physiological mechanisms behind these correlations are unknown as yet, several lines of evidence indicate that these correlations are causal.

Journal Article↗
PubMed1984

A monoclonal antibody recognizes structural variation in cystic fibrosis alpha 2-macroglobulin.

alpha 2-Macroglobulin (alpha 2M) is a major plasma protease inhibitor that has been studied because of its suggested role in the pathology of cystic fibrosis (CF). A panel of monoclonal antibodies specific for human alpha 2M were produced and screened for their ability to bind to a number of human alpha 2M samples. We have used these antibodies to characterize individual antigenic sites in this protein. alpha 2M was purified from plasma by polyethylene glycol precipitation followed by zinc chelate chromatography. A total of 23 alpha 2M samples in the native configuration, as well as the nucleophile-treated configuration, were screened by the panel of 18 monoclonal antibodies in an enzyme-linked immunosorbent assay procedure. Five of the samples tested were from individuals with cystic fibrosis. alpha 2M from family members of two of these patients was subsequently tested for reactivity with the monoclonal antibodies. One antibody, SAM94, exhibited a significant difference in binding to alpha 2M obtained from CF patients as compared with control individuals. This difference was particularly apparent in the binding of SAM94 to the nucleophile-treated CF alpha 2M; SAM94 showed significantly reduced binding to four of five unrelated CF individuals (p less than 0.005) and three of four cystic fibrosis obligate heterozygotes (p less than 0.005).

Antibodies, Monoclonal↗