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R Butler

Publications and source records attributed to R Butler.

At least 73 records · Page 4Linked to original sources
PubMed1991

Association of a genetic polymorphism in human apolipoprotein B-100 with intermediate density lipoprotein concentrations.

Immunochemical techniques have been used to identify five antigenic (Ag) sites on apolipoprotein B-100 (apoB), the major protein constituent of very low density (VLDL), intermediate density (IDL), and low density lipoproteins (LDL). Each Ag site results from allelic variation at a specific locus of the apoB gene. In the present study, we assessed whether variations in the five Ag loci were associated with concentrations of plasma lipids or lipoprotein fractions measured by analytical ultracentrifugation in a group of 44 healthy men. Pair-wise analyses of the Ag markers revealed that Ag(a1/d), in association with either Ag(x/y) or Ag(t/z), is significantly related to plasma IDL-mass concentrations. In this cohort we detected no significant associations of the Ag alleles (singly or in combination) with plasma total cholesterol, triglycerides, LDL-cholesterol, HDL-cholesterol, or mass of total VLDL or LDL. These results suggest that genetic variations in the apoB molecule may predispose to variations in concentrations of IDL that could have consequences for atherosclerotic risk.

Adult↗
PubMed1991

Lung edema formation following inhalation injury: role of the bronchial blood flow.

We investigated the contribution of the bronchial blood flow to the lung lymph flow (QL) and lung edema formation after inhalation injury in sheep (n = 18). The animals were equally divided into three groups and chronically prepared by implantation of cardiopulmonary catheters and a flow probe on the common bronchial artery. Groups 1 and 2 sheep were insufflated with 48 breaths of cotton smoke while group 3 received only room air. Just before injury, the bronchial artery of group 2 animals was occluded. The occlusion was maintained for the duration of the 24-h study period. At the end of the investigation, samples of lung were taken for determination of blood-free wet weight-to-dry weight ratio (W/D). Inhalation injury induced a sevenfold increase in QL in group 1 (7 +/- 1 to 50 +/- 9 ml/h; P less than 0.05) but only a threefold increase in group 2 (10 +/- 2 to 28 +/- 7 ml/h; P less than 0.05). The mean W/D value of group 1 animals was 23% higher than that of group 2 (5.1 +/- 0.4 vs. 3.9 +/- 0.2; P less than 0.05). Our data suggest that the bronchial circulation contributes to edema formation in the lung that is often seen after the acute lung injury with smoke inhalation.

Animals↗
PubMed1991

Bacterial sampling by absorbent paper points. An in vitro study.

This in vitro study was designed to test the hypothesis that sampling of bacterial suspensions by absorbent paper points would accurately reflect the proportion of the bacterial species whether they are homogeneously or non-homogeneously distributed in the sample site. The non-homogeneously distributed populations consisted of equal numbers of colony forming units (CFU) of two periodontal bacterial species present as separate cultures, one layered on top of the other. The species in the top layer accounted for greater than 90% of the total number of CFU detected by paper point sampling, regardless of which species formed the top layer. In contrast, when the layers were mixed prior to sampling to give a homogeneous bacterial distribution, the paper points detected equal numbers of CFU of each species. Thus the hypothesis was not supported and the proportions yielded by paper point sampling are not the same when the bacteria are non-homogeneously distributed as when they are homogeneously distributed. Ultrastructural observations have documented a non-homogeneous distribution of bacterial species in periodontal pockets. If the specific microbiota in the apical portion of deep periodontal pockets are important to the periodontal disease process, these data suggest that bacterial samples obtained by absorbent paper points misrepresent the presence of such bacterial species.

Absorption↗
PubMed1990

Isolation of cDNA clones using yeast artificial chromosome probes.

The cloning of large DNA fragments of hundreds of kilobases in Yeast artificial chromosomes, has simplified the analysis of regions of the genome previously cloned by cosmid walking. The mapping of expressed sequences within cosmid contigs has relied on the association of genes with sequence motifs defined by rare-cutting endonucleases, and the identification of sequence conservation between species. We reasoned that if the contribution of repetitive sequences to filter hybridizations could be minimised, then the use of large cloned DNAs as hybridisation probes to screen cDNA libraries would greatly simplify the characterisation of hitherto unidentified genes. In this paper we demonstrate the use of this approach by using a YAC, containing 180 kb of human genomic DNA including the aldose reductase gene, as a probe to isolate an aldose reductase cDNA from a lambda gt11 human foetal liver cDNA library.

Aldehyde Reductase↗
PubMed1990

A novel, rapid method for the isolation of terminal sequences from yeast artificial chromosome (YAC) clones.

The recent development of yeast artificial chromosome (YAC) vectors has provided a system for cloning fragments that are over ten times larger than those that can be cloned in more established systems. We have developed a method for the rapid isolation of terminal sequences from YAC clones. The YAC clone is digested with a range of restriction enzymes, a common linker is ligated to the DNA fragments and terminal sequences are amplified using a vector specific primer and a linker specific primer. Sequence data derived from these terminal specific products can be used to design primers for a further round of screening to isolate overlapping clones. The method also provides a convenient method of generating Sequence Tagged Sites for the mapping of complex genomes.

Base Sequence↗
PubMed1990

A 3.5 genome equivalent multi access YAC library: construction, characterisation, screening and storage.

The construction of a yeast artificial chromosome (YAC) primary gridded library of 35,000 clones from human lymphoblastoid (48,XXXX) cell line DNA is described. The average YAC size is approximately 350kb representing a greater than 3.5 times coverage of the genome. The library is stored at -70 degrees C as gridded clones on nylon filters impregnated with 20% glycerol and as glycerol suspensions of individual clones in microtitre plates providing a prolonged multi-user potential. To date we have used 14 single copy probes to screen this library by colony hybridisation as well as PCR and have isolated between 1 and 5 YAC clones for every probe.

Cell Line↗
PubMed1990

Tail docking.

Explore the source record for details and available documents.

Animal Welfare↗
PubMed1990

A mycobacterial 65-kD heat shock protein induces antigen-specific suppression of adjuvant arthritis, but is not itself arthritogenic.

A recombinant (r)65-kD protein from Mycobacterium leprae, at levels far in excess of those present in whole mycobacteria, was unable to induce arthritis. Even when combined with a synthetic adjuvant, CP20961, to mimic the peptidoglycan adjuvant component of the mycobacterial cell wall, the r65-kD protein failed to induce arthritis. Pretreatment with as little as 1 microgram r65-kD protein protected rats against arthritis induced by M. tuberculosis, but this r65-kD protein was markedly less able to protect against arthritis induced by the synthetic adjuvant, CP20961, or type II collagen. The r65-kD protein appears, therefore, to produce an antigen-specific protection against arthritis induced by bacterial cell walls containing the 65-kD protein. Such protection can be overcome, however, by arthritogenic T lymphocytes, suggesting that protection occurs by preventing clonal proliferation of autoreactive T lymphocytes that are induced by the adjuvant properties of mycobacterial cell walls. How the r65-kD protein abrogates this particular adjuvant activity, and the nature of the arthritogenic self antigen(s), remain to be elucidated.

Animals↗
PubMed1990

Rapid typing of apolipoprotein B DNA polymorphisms by DNA amplification. Association between Ag epitopes of human apolipoprotein B-100, a signal peptide insertion/deletion polymorphism, and a 3'flanking DNA variable number of tandem repeats polymorphism of the apolipoprotein B gene.

We present here rapid and efficient methods for the analysis of multiple variable apolipoprotein (apo) B loci using polymerase chain reaction based techniques. For illustrative purposes, we have applied these methods to establish an association between these polymorphisms and the apo B Ag immunological epitopes. The 5 DNA polymorphisms include 3 restriction endonuclease sites (for XbaI, EcoRI and MspI), a variable number of tandem repeat (VNTR) locus at the 3' end of the apo B gene, and an insertion/deletion polymorphism involving the signal peptide region of apo B. The latter two newly described polymorphisms are directly detectable following amplification and may have physiological effects on apo B expression because of their critical locations. All of these sites were typed using flanking oligonucleotides and the newly developed polymerase chain reaction. Amplification products were typed either directly (3' VNTR and signal peptide insertion/deletion alleles), or following specific enzyme digestion (for the restriction sites), or by allele specific oligonucleotides. The detailed methods presented will prove generally useful for rapidly typing DNA variation in the apo B gene. Using these techniques, we found a significant linkage disequilibrium between the Ag(t/z) locus and the 3' VNTR, and the Ag(c/g) locus and the signal peptide length polymorphism. Future association studies using these DNA polymorphisms should take into consideration that observed effects may be related to its linkage disequilibrium with the Ag loci and vice versa.

Alleles↗
PubMed1990

The effects of mastery and competitive conditions on self-assessment at different ages.

It was hypothesized that self-evaluative accuracy will increase with age in a competitive condition, while even young children will appraise their performance quite accurately in a mastery condition. Children at ages 5, 7, and 10 working in either a match-the-standard or a competitive condition copied a drawing and then evaluated their copies. As hypothesized, competing 5-year-olds overestimated the quality of their copies, and self-assessments became less positive and better correlated with adult judgments with age. There were no age differences in self-evaluative accuracy in the mastery condition. Examination of children's explanations for their ratings and their interest in the task supported the interpretation that young children are guided by a nonnormative concept of ability, which can lead to overoptimistic perceptions of competence under competition. Older children tended to adopt normative goals and criteria for self-assessment in competition and mastery ones in the match the standard condition, and were realistic about their performance in both.

Aptitude↗
PubMed1990

When pupils do not understand the determinants of their success and failure in school: relations between internal, teacher and unknown perceptions of control and school achievement.

Both dispositional and attributional perspectives on perceptions of control assume that people have some idea of outcome determinants. This, however, may not always be so. This study tested the hypothesis that pupils do not always understand the determinants of their learning outcomes, and that such a sense of unknown control will be associated with poor achievement in school. The study was unusual in that it tapped both dispositional control perceptions, using the new MMPCC, and causal attributions for success and failure in a school examination. Subjects were 186 10-year-old Israeli pupils of heterogeneous SES. Results confirmed that unknown control emerged as a distinct dimension of perceived control in both dispositional and attributional measures, and was consistently associated with poor achievement in school. Attributions of test outcomes to unknown causes were strongly related to dispositional unknown control, and were not affected by success or failure. In contrast, dispositional and attributional internality were unrelated, and did not predict achievement. It is argued that internal beliefs reflect internalised social-educational norms, and as a result have less impact on motivation than perceptions of unknown control. The implications of these findings for educational practice and motivational interventions are discussed.

Achievement↗
PubMed1989

The thieno[3,2-c]pyridine and furo[3,2-c]pyridine rings: new pharmacophores with potential antipsychotic activity.

Two new arylpiperazine derivatives, the 4-(1-piperazinyl)thieno- and -furo[3,2-c]pyridine ring systems, have been synthesized and appended via tetramethylene chains to various imide rings. Target compounds from each series were found to have significant activity in the blockade of apomorphine stereotypy and apomorphine-induced climbing, the Sidman avoidance response, and the conditioned avoidance response. In addition, while potent affinity for serotonin 5-HT1 and 5-HT2 receptors was observed for both the thieno- and furo[3,2-c]pyridine derivatives, the interaction of these molecules with the dopamine D2 receptor was weak. Electrophysiological studies of the lead prototypes from each series, involving compounds 22 and 33, indicate these two molecules have distinctively different effects on dopamine neurons in areas A9 and A10. Despite the similarity these molecules share in their behavioral indices of antipsychotic activity, it is likely that the thieno- and furo[3,2-c]pyridine rings employ different mechanisms to achieve this convergence of biological effects.

Amphetamines↗
PubMed1989

Mastery versus ability appraisal: a developmental study of children's observations of peers' work.

This study was designed to test the hypothesis that there is an age-related shift from mastery enhancement to relative ability assessment in the goal of social comparison. Children at ages 5, 7, and 10 made pictures with stickers under conditions of high or low concern with relative performance (competition/no competition) and high or low procedural ambiguity (free design/copying a drawing). The effects of the manipulations on frequency of glancing at the experimenter and the drawing were similar at all ages; competition enhanced glancing at peers, however, only at ages 7 and 10. The hypothesized shift in the function of social comparison was further supported by age differences in children's explanations for glancing at peers and by the pattern of intercorrelations between glances at the 3 targets and between glances and picture quality. The results indicate how mastery-based comparisons can promote mastery and performance and illustrate some costs older children may pay for their tendency to observe others primarily to assess relative ability.

Achievement↗
PubMed1989

Evidence for a regenerative capacity in adult mammalian cardiac myocytes.

Cardiac muscle does not contain a copopulation of myogenic cells and is mitotically inactive; hence, any regenerative capacity of the myocardium most likely originates from viable fragments of damaged cells rather than mitogenic activity. To assess the extent of such tissue recovery, single doses of the drug bupivacaine were used to induce degeneration of rat ventricular myocytes, and histological evidence for tissue recovery was sought. Up to 1 wk posttreatment, extensive degeneration was found around the injection site. At 2 wk, evidence of regeneration could be seen, and at 3 wk posttreatment, some relatively normal looking tissue was found.

Animals↗
PubMed1988

Interactions of Mycobacterium lepraemurium with resident peritoneal macrophages; phagocytosis and stimulation of the oxidative burst.

Live Mycobacterium lepraemurium or 60Co-gamma-irradiated organisms stimulated a very weak oxidative burst compared with similar numbers of heat-killed organisms or with live M. microti. This was found to reflect the poor uptake of the living organisms rather than an absolute failure to stimulate an oxidative burst. It is possible, however, that phagocytosis of fewer than 3-4 bacteria may not trigger the respiratory burst. Pre-incubating live M. lepraemurium with sera from infected mice, but not with fresh normal mouse sera, resulted in enhanced phagocytosis with a concomitant increase in the oxidative burst. The level of opsonic activity correlated with the M. lepraemurium specific antibody titres. The opsonic activity appeared to be mediated by antigen-antibody activation of the classical complement pathway as heat-inactivation destroyed the activity.

Animals↗
PubMed1988

Macrophage activity in resistant and susceptible mouse strains infected with Mycobacterium lepraemurium.

The level of activation of peritoneal macrophages following subcutaneous inoculation of resistant (C57BL) and susceptible (BALB/c) mice was assessed by monitoring superoxide anion and hydrogen peroxide production and also tumour cell cytostasis. The level of systemic macrophage activation appeared to correlate with bacterial load, rather than resistance to infection. It was observed that the more susceptible (BALB/c) strain developed higher and more sustained levels of systemic macrophage activation, whereas the more resistant (C57BL) strain showed only low transient levels of macrophage activation. In contrast, in vivo challenge of subcutaneously infected C57BL mice, via the intra-peritoneal route, with heat-killed Mycobacterium lepraemurium and thioglycollate resulted in a high level of macrophage activation compared with similarly treated uninfected mice. Similar treatment of susceptible BALB/c mice, however, did not result in enhanced macrophage activation. It was also observed that high levels of macrophage activation occurred in T-cell deprived C57BL mice following infection with M. lepraemurium.

Animals↗