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Biomedical subjects

R J Drummond

Publications and source records attributed to R J Drummond.

At least 19 recordsLinked to original sources
PubMed2005

Orthodontic status and treatment need of 12-year-old children in South Africa using the Dental Aesthetic Index.

OBJECTIVE: The aim of this study was to determine the prevalence and severity of malocclusion and orthodontic treatment needs in a sample of 12-year-old South African school children using the Dental Aesthetic Index (DAI), and to assess the relationship between malocclusion and certain socio-demographic variables. METHODOLOGY: The sample comprised 6142, 12-year-old children attending school in seven of the nine provinces of South Africa. For each subject the standard demographic information such as gender, population group, location type and employment status of the parents was collected, after which an intra-oral examination for occlusal status using the DAI was performed. Before the survey, the examiners were calibrated and trained and only examiners with an agreement score greater or equal to 80 per cent were included in the final study. RESULTS: The results showed that 47.7 per cent of the children in the sample presented with good occlusion or minor malocclusion, just over 52.3 per cent presented with identifiable malocclusion, a DAI score larger than 26. Of these, 21.2 per cent had definite malocclusion, 14.1 per cent had severe malocclusion and 16.9 per cent had very severe or handicapping malocclusion. Malocclusion as defined in this study was found to be significantly associated with the different population groups in South Africa, with gender and with dentition stage, but not with the location type or the employment status of parents. CONCLUSIONS: The results of this study show a high prevalence of malocclusion in 12-year-old South African children. The findings provide reliable base-line data regarding the prevalence, distribution and severity of malocclusion as well as useful epidemiological data on the orthodontic treatment needs of 12-year-old children in South Africa.

Child↗
PubMed1999

Urokinase receptor antagonists: discovery and application to in vivo models of tumor growth.

Urokinase receptor antagonists based on the growth factor domains of both human and murine urokinase which show sub-nanomolar affinities for their homologous receptors have been expressed as recombinant proteins. Further modification of these molecules by preparing fusions with the constant region of human IgG has led to molecules with high affinities and long in vivo half-lives. Smaller peptidic inhibitors have been obtained by a combination of bacteriophage display and peptide analog synthesis. All of these molecules inhibit the binding of the growth factor domain of uPA to the uPA receptor and enhance binding of the uPA receptor to vitronectin. Protein uPA receptor antagonists were tested in an in vivo tumor model using the human breast carcinoma MDAmb231 in immunodeficient mice. Both human and murine receptor antagonists showed significant inhibition of primary tumor growth, demonstrating that in vivo, both tumor and stromal cell uPA receptor dependent plasminogen activation can modulate tumor growth.

Amino Acid Sequence↗
PubMed1994

Identification of the urokinase receptor as an adhesion receptor for vitronectin.

Urokinase receptors, expressed on surfaces of many cell types, focus to the pericellular space plasminogen-dependent proteolysis important in matrix remodeling and cell movement. We now report that the urokinase receptor (uPAR) is also a high affinity (Kd < 30 nM) receptor for vitronectin. Recombinant uPAR binds vitronectin in the absence of urokinase, but vitronectin binding is promoted by concurrent receptor binding of either urokinase or fragments thereof containing its uPAR binding domain. Stable epithelial cell transfectants expressing membrane-anchored uPAR, but not cells expressing soluble uPAR, become strongly adhesive with altered morphology in the absence of urokinase. These observations identify a new class of vitronectin receptor and imply a duality in function for the receptor that intrinsically links matrix adhesion to regulation of protease activity. Increases in urokinase receptor expression known to be associated with cellular activation and malignant transformation could modulate cellular trafficking and function by promoting attachment to vitronectin.

Adsorption↗
PubMed1992

Learning style and personality type.

To investigate the relations between the Myers-Briggs Type Indicator and the Gregorc Style Delineator and to examine the construct validity of the Style Delineator, 41 undergraduate students preparing to be teachers were given both tests. Observed differences in learning styles by personality type partially support the construct validity of the Style Delineator. Judging individuals (n = 25) tended to perceive themselves as concrete sequential thinkers as opposed to perceptive individuals (n = 16) who thought of themselves as concrete random thinkers. Feeling types (n = 29) tended to prefer random modes of thinking.

Adult↗
PubMed1992

Work values of black, unwed adolescent parents.

The work values of black unwed adolescent parents were explored using the Values Scale. On 21 scales, the scores of 47 youth (12 to 20 years old) were compared with those of a preliminary normative sample presented in the test manual. Significant differences between the two groups were found on 16 of the 21 scales. The values of these black adolescent parents were less crystallized than were those of the normative group and reflect the concern for this group's satisfaction of their basic needs in which physical, safety, and self-esteem needs appeared most dominant.

Adolescent↗
PubMed1991

Dimensions of self-concept of pregnant unwed teens.

The study examined the self-esteem of pregnant teens enrolled in a program designed to maximize their chances of completing school. The Culture Free Self-Esteem Inventory (Battle, 1981) and the Coopersmith (1981) Self-Esteem Inventory were completed by the teens. The mean score of the group on the Culture Free Total Self Scale was below average in comparison to the norm.

Achievement↗
PubMed1991

Genetic organization and regulation of the xylose degradation genes in Streptomyces rubiginosus.

The xylose isomerase (xylA) and the xylulose kinase (xylB) genes from Streptomyces rubiginosus were isolated, and their nucleotide sequences were determined. The xylA and xylB genes encode proteins of 388 and 481 amino acids, respectively. These two genes are transcribed divergently from within a 114-nucleotide sequence separating the coding regions. Regulation of the xyl genes in S. rubiginosus was examined by fusing their promoters to the Pseudomonas putida catechol dioxygenase gene and integrating the fusions into the minicircle integration site on the S. rubiginosus chromosome. The expression of catechol dioxygenase was then measured under a variety of conditions. The results indicated that transcription of the xyl genes was induced by D-xylose and repressed by glucose. Data from quantitative S1 mapping were consistent with this conclusion and suggested that xylA had one and xylB had two transcription initiation sites. The transcription initiation site of xylA was 40 bp upstream of the coding region. The two transcription initiation sites of xylB were 20 and 41 bp 5' of its translation initiation codon. Under control of appropriate regulatory elements, the cloned xyl genes are capable of complementing either Escherichia coli xylose isomerase- or xylulose kinase-deficient strains. The deduced amino acid sequence of the S. rubiginosus xylA protein is highly homologous to sequences of other microbial xylose isomerases.

Aldose-Ketose Isomerases↗
PubMed1988

Alteration of amino-terminal codons of human granulocyte-colony-stimulating factor increases expression levels and allows efficient processing by methionine aminopeptidase in Escherichia coli.

We have improved the expression of recombinant human granulocyte-colony-stimulating factor (G-CSF), produced by either pL or trpP expression vectors in Escherichia coli, by altering the sequence at the 5' end of the G-CSF-coding region. Initial attempts to express G-CSF resulted in neither detectable G-CSF mRNA nor protein in the trpP system, and only G-CSF mRNA was detectable in the pL system. We modified both expression vectors to decrease the G + C content of the 5' end of the coding region without altering the predicted amino acid sequence. This resulted in expression of detectable G-CSF mRNA and protein in both systems. Expression reached 17% and 6.5% of the total soluble cellular protein in the pL and trpP expression systems, respectively. The N-terminal sequence of the recombinant G-CSF from the pL system was Met-Thr-Pro-Leu-Gly-Pro-. G-CSF isolated from several human cell lines (including the LD-1 cell line reported here), does not have an N-terminal methionyl residue. Deletion of the threonine codon at the beginning of the coding region for the mature G-CSF resulted in efficient removal of the N-terminal methionine residue during expression in E. coli.

Aminopeptidases↗
PubMed1984

Binding of 125I-labeled recombinant beta interferon (IFN-beta Ser17) to human cells.

We investigated the binding of 125I-labeled beta interferon (IFN-beta Ser17), a nonglycosylated recombinant human fibroblast interferon in which cysteine at position 17 is replaced by serine by site-specific mutagenesis. An optimized chloramine T radiolabeling method produced a highly labeled, fully active 125I-IFN suitable for these studies. Unlike the case with the chloramine T method, incorporation of a single mole of Bolton-Hunter reagent into a mole of IFN-beta Ser17 led to nearly complete loss of biological activity. 125I-IFN-beta Ser17, prepared by the chloramine T method, bound specifically to human lymphoblastoid cells (Daudi) with a dissociation constant of 0.24 nM. The number of binding sites per cell was 4,000. In competition assays, unlabeled beta interferons (native, recombinant IFN-beta Cys17, and various preparations of IFN-beta Ser17) equally displaced labeled IFN-beta Ser17 on Daudi cells. Recombinant IFN-alpha-1 displaced 125I-IFN-beta binding to Daudi cells less efficiently than did unlabeled native or recombinant beta interferon. However, at the concentrations tested, native gamma interferon showed no competition with 125I-IFN. Our results indicate that IFN-beta Ser17 and native IFN-beta posses similar binding properties.

Binding Sites↗
PubMed1983

Localization of 2',3'-cyclic nucleotide-3'-phosphohydrolase within the vertebrate retina.

Histochemical and immunochemical techniques are used to locate 2',3'-cyclic nucleotide-3'-phosphohydrolase (2',3'-cNMP-3'ase) within cells of the vertebrate retina. A new histochemical method is described which links the hydrolysis of 2',3'-cNADP to the formation of a reduced, insoluble tetrazolium formazan. Photoreceptors from fish, bovine, and rat retinas are stained by this procedure. The reaction is blocked by 2'-AMP, a known inhibitor of 2',3'-cNMP-3'ase. Rabbit antibodies prepared against 2',3'-cNMP-3'ase from bovine brain are found to cross-react with bovine and rat retinal enzymes. Peroxidase-labeled antibody shows by light microscopy the greatest staining along the inner segments of the photoreceptors. Electron microscopy of the same preparations confirms binding to the plasma membrane of the inner segments of both rods and cones. Retinal 2',3'-cNMP-3'ase is thus predominantly associated with the photoreceptors, suggesting some role for 2',3'-cyclic nucleotides as substrates in visual function.

2',3'-Cyclic-Nucleotide Phosphodiesterases↗
PubMed1980

Comparison of 2',3'-cyclic nucleotide 3'-phosphodiesterase and the major component of Wolfgram protein W1.

Wolfgram protein preparations from myelin are heterogeneous mixtures having major components with molecular weights in the 43,000 to 60,000 range. Through the use of an SDS-slab gel electrophoretic system of high resolving power, the Wolfgram 1 (W1) component described by Nussbaum et al. (1977) has been resolved into two components; bovine W1a and W1b proteins are found to have mobilities identical to those of the two 2',3'-cyclic nucleotide 3'-phosphodiesterase (2'3'-CN 3'-ase) components, CNa and CNb (Drummond, 1979). Crossed immunoelectrophoresis with bovine 2',3'-CN 3'-ase demonstrates that CNa and CNb are antigenically indistinguishable. Rat and bovine Wolfgram proteins W1a and W1b, but not the W2 proteins, display cross reactivity with antiserum directed against bovine 2',3'-CN 3'-ase. Chymotryptic and Staphylococcus aureus V8 protease peptide profiles indicate structural similarities between proteins CNa-W1a and CNb-W1b. It is concluded that an inactivated form of 2',3'-Cn 3'-ase is a major component of Wolfgram protein W1. These results are consistent with the studies on the histochemical localization of rat W1 protein by Roussel et al. (1977, 1978).

2',3'-Cyclic-Nucleotide Phosphodiesterases↗
PubMed1977

An investigation of relationships between teachers' ratings of behavior and children's personality traits.

This study examined the relationships between teachers' ratings of children's behavior on the Behavior Problem Checklist and children's self-reported personality source traits on age-appropriate Personality Questionnaires. The sample consisted of 254 children from first through eighth grades and 13 teachers in a rural Maine elementary school. Analysis of the data revealed that teachers' ratings and children's self-reports in grades four through six agreed more frequently about problematic behavior than did children's self-reports and teachers self-ratings in grades one through three and seven and eight. In general, the study (1) supported the validity of teacher judgments made with the Behavior Problem Checklist, (2) demonstrated the critical need for more than one perspective when identifying and defining maladaptive behavior potentially indicative of emotional disturbance, and (3) suggested the need to increase the accuracy of teachers' perceptions and evaluations of children's behavior.

Adolescent↗