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Biomedical subjects

R D Taylor

Publications and source records attributed to R D Taylor.

At least 19 recordsLinked to original sources
PubMed2006

Origin of the Verwey transition in magnetite.

Comprehensive x-ray powder diffraction studies were carried out in magnetite in the 80-150 K and 0-12 GPa ranges with a membrane-driven diamond anvil cell and helium as a pressure medium. Careful data analyses have shown that a reversible, cubic to a distorted-cubic, structural transition takes place with increasing pressure, within the (P,T) regime below the Verwey temperature TV(P). The experimental documentation that TV(P)=Tdist(P) implies that the pressure-temperature-driven metal-insulator Verwey transition is caused by a gap opening in the electronic band structure due to the crystal-structural transformation to a lower-symmetry phase. The distorted-cubic insulating phase comprises a relatively small pressure-temperature range of the stability field of the cubic metallic phase that extends to 25 GPa.

Journal Article↗
PubMed2004

Pressure induced self-oxidation of Fe(OH)2.

Mössbauer spectroscopy, x-ray diffraction, and electrical resistance [R(P,T)] studies in Fe(OH)(2) to 40 GPa revealed an unforeseen process by which a gradual Fe2+ oxidation takes place, starting at approximately 8 GPa reaching 70% Fe3+ abundance at 40 GPa. The nonreversible process Fe2+-->Fe3++e(-) occurs with no structural transition. The "ejected" electrons form a deep band within the high-pressure electronic manifold becoming weakly localized at P>50 GPa. This process is attributed to an effective ionization potential created by the pressure induced orientationally deformed (OH) dipoles and the unusual small binding energy of the valence electron in Fe2+(OH)(2).

Journal Article↗
PubMed2004

The incorporation of whole grain into pelleted broiler chicken diets. II. Gastrointestinal and digesta characteristics.

1. Pelleted diets, incorporating whole or ground wheat or barley in the pellets, were fed to broiler chickens and the performance, gastrointestinal development and digesta characteristics of those chickens recorded. 2. Body weight was similar with whole grain incorporation or enzyme application. Food conversion efficiency was improved by addition of enzyme to a full wheat diet. 3. Whole grain inclusion in pellets reduced proventriculus proportional mass and increased gizzard proportional mass with no apparent effects of exogenous feed enzyme addition. 4. Relative ileal mass was reduced by enzyme inclusion in a wheat diet and by inclusion of whole barley in the pellets. 5. Digesta viscosity was increased by whole wheat inclusion but reduced by enzyme inclusion irrespective of grain processing. Inclusion of 200 g/kg of barley did not alter viscosity of digesta beyond the duodenum. 6. Fresh excreta pH was higher with both cereals in the grower phase when whole grain was fed. On the barley diet, this was affected by enzyme addition, which created higher pH from a point earlier in the grower phase than when no enzyme was employed. 7. Evidence of a complex interaction between higher viscosity and pH being involved in differences in ileal relative mass was found through significant relationships being produced by enzyme use on the wheat diet alone.

Aging↗
PubMed2004

The influence of whole grain inclusion in pelleted broiler diets on proventricular dilatation and ascites mortality.

1. Pelleted diets, incorporating whole or ground wheat or barley in the pellets, were fed to broiler chickens and proventricular dilatation, digesta characteristics and mortality were recorded. 2. The incidence of proventricular dilatation was reduced when whole grain was incorporated into pelleted diets at 200 g/kg. 3. Enzyme application did not influence proventricular dilatation. 4. Digesta contents of intestinal sections were greater and pH lower in anterior intestinal sections when birds had dilated proventriculi. 5. Consideration of overall ascites mortality suggests that the incidence of the condition may be curtailed by whole grain inclusion in pelleted diets. 6. Production efficiency may be enhanced with whole grain inclusion in pellets when feed processing costs and flock health responses are considered.

Animal Feed↗
PubMed2002

A review of protein-small molecule docking methods.

The binding of small molecule ligands to large protein targets is central to numerous biological processes. The accurate prediction of the binding modes between the ligand and protein, (the docking problem) is of fundamental importance in modern structure-based drug design. An overview of current docking techniques is presented with a description of applications including single docking experiments and the virtual screening of databases.

Algorithms↗
PubMed2001

TANK2, a new TRF1-associated poly(ADP-ribose) polymerase, causes rapid induction of cell death upon overexpression.

Tankyrase (TANK1) is a human telomere-associated poly(ADP-ribose) polymerase (PARP) that binds the telomere-binding protein TRF1 and increases telomere length when overexpressed. Here we report characterization of a second human tankyrase, tankyrase 2 (TANK2), which can also interact with TRF1 but has properties distinct from those of TANK1. TANK2 is encoded by a 66-kilobase pair gene (TNKS2) containing 28 exons, which express a 6.7-kilobase pair mRNA and a 1166-amino acid protein. The protein shares 85% amino acid identity with TANK1 in the ankyrin repeat, sterile alpha-motif, and PARP catalytic domains but has a unique N-terminal domain, which is conserved in the murine TNKS2 gene. TANK2 interacted with TRF1 in yeast and in vitro and localized predominantly to a perinuclear region, similar to the properties of TANK1. In contrast to TANK1, however, TANK2 caused rapid cell death when highly overexpressed. TANK2-induced death featured loss of mitochondrial membrane potential, but not PARP1 cleavage, suggesting that TANK2 kills cells by necrosis. The cell death was prevented by the PARP inhibitor 3-aminobenzamide. In vivo, TANK2 may differ from TANK1 in its intrinsic or regulated PARP activity or its substrate specificity.

Amino Acid Sequence↗
PubMed2001

The incorporation of whole grain into pelleted broiler chicken diets: production and physiological responses.

1. Pelleted diets, incorporating whole or ground triticale or wheat in the pellets, were fed to broiler chickens and the performance, gastro-intestinal development and health of those chickens recorded. 2. The use of whole triticale in the pelleted food produced similar bodyweight responses to when ground triticale was incorporated in the food. Food conversion efficiency was enhanced when whole triticale was used compared to ground triticale and was similar to when an exogenous enzyme was added to the ground triticale diet. The incorporation of whole wheat into the pelleted food produced similar production responses to the use of ground wheat. 3. The gastro-intestinal development of the birds was greater when they were fed the whole grain diet as gizzard weights were increased by the incorporation of whole grain into the diet. Gastro-intestinal development was thought to be related to the presence of large fibre particles in the food. 4. Proventricular dilatation and mortality due to ascites were reduced by feeding pelleted diets containing whole grain, which was possibly related to the early development of the gastro-intestinal tract relative to total body development. 5. It is suggested that the current use of exogenous enzyme additions to broiler diets may be reduced by incorporating whole grain into pelleted diets for broiler chickens.

Animal Feed↗
PubMed2001

Structural requirements of Tom40 for assembly into preexisting TOM complexes of mitochondria.

Tom40 is the major subunit of the translocase of the outer mitochondrial membrane (the TOM complex). To study the assembly pathway of Tom40, we have followed the integration of the protein into the TOM complex in vitro and in vivo using wild-type and altered versions of the Neurospora crassa Tom40 protein. Upon import into isolated mitochondria, Tom40 precursor proteins lacking the first 20 or the first 40 amino acid residues were assembled as the wild-type protein. In contrast, a Tom40 precursor lacking residues 41 to 60, which contains a highly conserved region of the protein, was arrested at an intermediate stage of assembly. We constructed mutant versions of Tom40 affecting this region and transformed the genes into a sheltered heterokaryon containing a tom40 null nucleus. Homokaryotic strains expressing the mutant Tom40 proteins had growth rate defects and were deficient in their ability to form conidia. Analysis of the TOM complex in these strains by blue native gel electrophoresis revealed alterations in electrophoretic mobility and a tendency to lose Tom40 subunits from the complex. Thus, both in vitro and in vivo studies implicate residues 41 to 60 as containing a sequence required for proper assembly/stability of Tom40 into the TOM complex. Finally, we found that TOM complexes in the mitochondrial outer membrane were capable of exchanging subunits in vitro. A model is proposed for the integration of Tom40 subunits into the TOM complex.

Amino Acid Sequence↗
PubMed2000

Influence of the method of calcium provision on Marek's disease losses in compound and choice fed layers.

1. Two strains of layers were fed compound or choice forms of a standard diet and given calcium as either ground limestone or coarse limestone grit daily or every 2nd day. Mortality caused by Marek's disease was monitored during the rearing and laying phases. 2. A dramatic difference in Marek's disease mortality was found between the strains. Heavy Marek's disease mortality in the imported strain A in the rearing phase was not markedly affected by dietary or calcium treatment. 3. Method of feeding and calcium provision interacted to influence significantly the risk of death due to Marek's disease in the laying phase in layer strain A. 4. Choice feeding may adversely influence Marek's disease losses in layers.

Animal Feed↗
PubMed2000

Proneness to eating disorders: weightlifters compared to exercisers.

Previous findings were confirmed suggesting that weightlifters may be more prone to eating disorders than are casual exercisers. 25 weightlifters' mean eating disorder score was significantly higher than that of 25 casual exercisers when contrasted for practical difference.

Adult↗
PubMed1998

U-richness is a defining feature of plant introns and may function as an intron recognition signal in maize.

Using a large set of plant gene sequences we compared individual introns to their flanking exons. Both Zea mays and Arabidopsis thaliana introns are U-rich but display no apparent bias for A. We identified fifteen 11-mer U-rich motifs as frequent elements of maize introns, and these are virtually absent from exons. By mutagenesis, we show that the single U-rich motif in the Bronze2 intron of maize plays a key role in intron processing in vivo.

Base Composition↗
PubMed1997

Reconstitution of human telomerase with the template RNA component hTR and the catalytic protein subunit hTRT.

The maintenance of chromosome termini, or telomeres, requires the action of the enzyme telomerase, as conventional DNA polymerases cannot fully replicate the ends of linear molecules. Telomerase is expressed and telomere length is maintained in human germ cells and the great majority of primary human tumours. However, telomerase is not detectable in most normal somatic cells; this corresponds to the gradual telomere loss observed with each cell division. It has been proposed that telomere erosion eventually signals entry into senescence or cell crisis and that activation of telomerase is usually required for immortal cell proliferation. In addition to the human telomerase RNA component (hTR; ref. 11), TR1/TLP1 (refs 12, 13), a protein that is homologous to the p80 protein associated with the Tetrahymena enzyme, has been identified in humans. More recently, the human telomerase reverse transcriptase (hTRT; refs 15, 16), which is homologous to the reverse transcriptase (RT)-like proteins associated with the Euplotes aediculatus (Ea_p123), Saccharomyces cerevisiae (Est2p) and Schizosaccharomyces pombe (5pTrt1) telomerases, has been reported to be a telomerase protein subunit. A catalytic function has been demonstrated for Est2p in the RT-like class but not for p80 or its homologues. We now report that in vitro transcription and translation of hTRT when co-synthesized or mixed with hTR reconstitutes telomerase activity that exhibits enzymatic properties like those of the native enzyme. Single amino-acid changes in conserved telomerase-specific and RT motifs reduce or abolish activity, providing direct evidence that hTRT is the catalytic protein component of telomerase. Normal human diploid cells transiently expressing hTRT possessed telomerase activity, demonstrating that hTRT is the limiting component necessary for restoration of telomerase activity in these cells. The ability to reconstitute telomerase permits further analysis of its biochemical and biological roles in cell aging and carcinogenesis.

Amino Acid Sequence↗
PubMed1995

Kinship support and maternal and adolescent well-being in economically disadvantaged African-American families.

This study tested a conceptual model developed to explain the link between kinship support and the psychological well-being of economically disadvantaged African-American adolescents. The relation of kinship support with maternal and adolescent well-being and mothers' child-rearing practices was assessed in 51 African-American families whose incomes placed them at or below the poverty threshold. Findings revealed that kinship social support to mothers/female guardians was positively associated with adolescent psychological well-being, maternal well-being, and more adequate maternal parenting practices (acceptance, firm control and monitoring of behavior, autonomy granting). Maternal well-being and more adequate maternal parenting practices were positively related to adolescent well-being. Evidence of the mediational role of maternal well-being and parenting practices was revealed. When the effects of maternal well-being and maternal parenting practices were controlled, significant relations between kinship support and adolescent well-being were no longer apparent.

Adaptation, Psychological↗
PubMed1994

Carotidynia.

Explore the source record for details and available documents.

Carotid Artery Diseases↗
PubMed1992

Teacher interactions in mainstream social studies and science classes.

This investigation was designed to change teacher-student interactions in middle school social studies and science classes. Eighteen of 35 teacher volunteers received a six-session inservice emphasizing teacher effectiveness variables. Results indicated significant differences between experimental and control teachers on a pre-post contrast, as well as on a follow-up (maintenance) contrast. Differential effects on the science and social studies teachers were seen. Similarities and differences related to student type, independent of the intervention, were obtained.

Child↗
PubMed1991

Crisis intervention: long-term training effects.

10 months following a crisis-intervention training program which focused on interpretation of signal events, 17 participants more frequently reported increased belief in their ability to recognize the need for intervention and to intervene effectively than did 22 control subjects. Perceived frequency of intervention by trained participants, however, had decreased rather than increased. Implications of the findings and recommendations for research are discussed.

Adult↗
PubMed1991

Black and white women's attitudes toward interracial marriage.

50 white women and 50 black women, US citizens between the ages 18 and 23 years, were asked to rate their attitudes about interracial marriage on a 10-point response scale. The white women were somewhat more favorable, if not significantly so, than the black women about men and women of their race marrying persons of another race. However, scorers at the extremes of the scale were significantly different. The white women tended to cluster at the scale extreme favoring interracial marriage, whereas the black women tended to cluster at the other unfavorable extreme. Implications and research needs are discussed.

Adolescent↗