PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “structural variations”

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 109 records · Page 6Linked to original sources
PubMed1990

Sequence-dependent structural variations of DNA revealed by DNase I.

Two global helix parameters important for DNA-DNase I interaction are the geometry of the minor groove and the DNA stiffness that resists bending toward major groove. Thus, local averaging of P-O3' bonds cutting frequencies (InP) reflects global helix parameters revealed by DNase I. Using the approximation that locally averaged InP values depend only on the type of the dinucleotide steps involved in the region of interaction, we calculated the collective contribution (sigma Dd) for ten different dinucleotide steps. Our results suggest that, at the first approximation, global varying helix parameters revealed by DNase I, might be predicted from sequence. Obtained sigma Dd function can be used as a sequence-dependent measure of protein-induced DNA flexure in the direction towards the major groove, which is usually connected to widening of the minor groove. In the course of analysis of Mg2+ and Mn2+ dependent DNase I digestions, no significant difference was found, in spite of the supposed differences in enzyme activity. These results suggest that if the second Mn2(+)-dependent active site exists, its activity is lower than that of the first one.

Base Sequence↗
PubMed1987

Antigenic and structural variation of the p28 core polypeptide of goat and sheep retroviruses.

The p28 core polypeptides of four isolates of caprine arthritis-encephalitis virus (CAEV) from goats was compared with those of visna virus (VV) and progressive pneumonia virus (PPV) from sheep. Monoclonal antibodies recognized p28 epitopes common to all six retrovirus isolates, a p28 epitope on four CAEV isolates, but not VV and PPV isolates, a p28 epitope on four CAEV isolates and VV, but not PPV and a p28 epitope unique to the CAEV isolate used for immunizing the mouse spleen donor. Comparison of two-dimensional maps of tyrosine containing tryptic peptides of p28 demonstrated that three CAEV isolates had similar maps while a fourth CAEV isolate, VV and PPV had several different from the three closely related CAEV p28s and from each other.

Animals↗
PubMedDate not supplied

Structural variations in the H-2 genes of AKR lymphomas.

K36.16 is an AKR H-2k thymoma which expresses an aberrant H-2Dd-like allospecificity, does not have a detectable amount of the H-2Kk syngeneic antigen and grows very easily in syngeneic mice. By DNA-mediated gene transfer experiments, we were able to obtain transformed clones which do express the H-2Kk molecules and are rejected by AKR mice. Southern hybridization was performed to assess whether any gross changes had occurred in the K36.16 H-2K locus or elsewhere in the MHC, which might explain the lack of H-2K expression and/or the presence of the aberrant H-2Dd-like allospecificity. Specific H-2 class I DNA probes were used to compare the K36.16 genomic DNA with normal AKR thymus DNA after digestion with a variety of restriction enzymes. After hybridization with the pH-2IIa probe a 2.8 kb 'Hind III' fragment was identified in the K36.16 genomic DNA which is absent from AKR DNA. The pH-2IIa probe detects the third, transmembrane and cytoplasmic domains of class I genes. Although these changes are indicative of MHC genome modifications it is not yet possible to link these specific Southern blot pattern variations with the phenotypic changes mentioned above.

Animals↗
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↗
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↗
PubMed1990

Effects of structural variation on Young's modulus of non-human cancellous bone.

The modulus of elasticity of cubes of cancellous bone, tested in three orthogonal directions, was measured along with apparent density, fabric (measured using image analysis techniques), connectivity and mineral volume fraction. Multiple regression was used to relate Young's modulus and the explanatory variables. The most important explanatory variable was apparent density; fabric was also important. Connectivity was highly correlated with apparent density, and so it is difficult to assign relative weights to these two variables. However, both have a significant, and separate, effect on Young's modulus. The total variance in Young's modulus explained by these three variables was about 85 per cent. This implies that other explanatory variables are either unimportant or highly correlated with the variables listed above. Mineral volume fraction is shown to be an unimportant variable, and arguments are produced why this is to be expected, even though it is highly important in explaining the variation in Young's modulus of compact bone.

Animals↗
PubMed1992

Structural variations in the jugular foramen of the human skull.

The jugular foramen was examined in 300 Anatolian skulls from the 17th and 18th centuries. In 61.6% the foramen was larger on the right and in 26% on the left, with the remainder being of almost equal size. An obvious dome caused by a superior jugular bulb was present bilaterally in 49%, on the right only in 36%, on the left only in 6%; it was absent bilaterally in 10.3%. Complete bony septation occurred in 5.6% on the right and in 4.3% on the left, partial septation was observed in 2.6% on the right and in 19.6% on the left. Another foramen which is completely separated by a spicule of bone and which transmits the inferior petrosal sinus was present in 5.6% of skulls on the right and in 4.6% on the left.

Cranial Nerves↗
PubMed1989

[Study on structural variation of nucleolar organizer regions (NOR) and the satellite association (SA)].

To further illustrate the biological significance of variant NOR (including double NOR--dNOR and triple NOR--tNOR) and satellite association (SA) and the relationship to meiotic non-disjunction (NDJ), this study was carried out in the normal population and the parents of patients with Down Syndrome (DS). Of 800 individuals, 4 dNOR carriers, two of them from the control and two from the non-informative experiments were detected. SA data for 3 out of the 4 dNOR carriers showed no statistical significant increase in SA when dNOR was present in the cell even in case 4 where two dNOR were found in one cell. However, ease 3 demonstrated significant decrease in SA when dNOR was present, although it showed that the overall incidence of dNOR was higher in this carrier than that in the other three. It is concluded that dNOR can be detected on any acrocentric chromosome and not be related to NDJ of chromosome, which is a heritable variant that does not affect phenotype and that there are two kinds of dNOR variants, one being from the translocation of the short arm of acrocentric chromosome, the other from non-translocation.

Adult↗
PubMed1989

Structural variations and growth potential of Yersinia enterocolitica under different culture conditions.

The growth potential and the polypeptide composition of Yersinia enterocolitica serotype 0:3 isolated from patients with uncomplicated diarrhoea, reactive arthritis or septicemia were evaluated under different culture conditions. The expression of polypeptides varied with presence of the virulence-associated 40-48 Mdal plasmid, growth medium, growth temperature and gas composition of the culture (air, carbon dioxide, oxygen). Also the initial growth medium at 26 degrees C, before temperature shift to 37 degrees C, influenced the subsequent growth potential and expression of polypeptides. The plasmid encoded at least 7 polypeptides. This plasmid also inhibited the multiplication of bacteria under defined culture conditions. The dominating plasmid-encoded polypeptides were optimally expressed in air or oxygen-supplemented growth medium. The majority of the chromosomally encoded polypeptides were expressed independently of presence of the plasmid, whereas the expression of at least 8 were repressed by the plasmid. Five chromosomally encoded polypeptides were expressed only in carbon dioxide and five only in oxygen environment. These results indicate that Y. enterocolitica may express different molecules in different environments in vivo. This may be of importance for host-parasite relationship and immune response.

Bacterial Proteins↗