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Biomedical subjects

M Clegg

Publications and source records attributed to M Clegg.

13 recordsLinked to original sources
PubMed2003

Implant surface roughness affects osteoblast gene expression.

The transcription factor Cbfa1 regulates osteoblast differentiation and expression of genes necessary for the development of a mineralized phenotype. The purpose of this study was to determine if Cbfa1 and BSPII gene expression are influenced by implant surface microtopography. Osteoblasts were cultured on 600-grit (grooved) or sandblasted (roughened) cpTi implant discs. Mineralization was evaluated by Alizarin-Red-S staining. Real Time PCR was used for quantitative analysis of Cbfa1 and BSPII gene expression. Enhanced mineralization was seen in osteoblasts grown on roughened implant surfaces relative to tissue culture plastic. Real Time PCR showed significant (P < 0.05) increases in Cbfa1 gene expression in cells grown on roughened, as compared with grooved, implant surfaces. BSPII gene expression was also increased on rough surfaces in the UMR cells, but was reduced in the rat calvarial osteoblast cultures. These results suggest that osteoblast gene expression and mineralization are affected by roughened implant surface microtopographies during osseointegration of dental implants.

Analysis of Variance↗
PubMed1999

A comparison of the nariokotome Homo erectus with juveniles from a modern human population.

The Nariokotome Homo erectus has an apparent disjunction of inferred age as judged by dental maturity, by epiphyseal closure and by stature, when compared to modern human norms. On this basis, it has been suggested that this fossil hominin differed in its pattern of growth and development from modern humans. In particular, the characteristic human adolescent growth spurt may not yet have been present, and in this sense H. erectus growth would be more ape-like than human-like. This study tests this conclusion by examining the variation in age as inferred from the maturity indicators in a modern human skeletal population of known age. The results show that all of the maturity indicators used in this analysis underage the test skeletons. Furthermore, there is also no consistency between the indicators; they do not agree in their inferred chronological ages. The disjunction between the maturity indicators in the test skeletons is similar in pattern to the disjunction observed in the Nariokotome Homo erectus. This is particularly true of the relationship between dental age and the other two indicators. These results suggest that the pattern observed in Nariokotome is within the normal range of variation found in modern humans. It does not necessarily indicate a different pattern of growth and development.

Adolescent↗
PubMed1999

Activation of chick tendon lysyl oxidase in response to dietary copper.

Lysyl oxidase (EC 1.4.3.13), a cuproenzyme, can account for 10-30% of the copper present in connective tissue. Herein, we assess the extent to which tissue copper concentrations and lysyl oxidase activity are related because the functional activity of lysyl oxidase and the copper content of chick tendon are both related to dietary copper intake. Chicks (1-d old) were fed diets (basal copper concentration, 0.4 microg/g diet) to which copper was added from 0 to 16 microg/g diet. Liver and plasma copper levels tended to normalize in chickens that consumed from 1 to 4 microg copper/g of diet, whereas tendon copper concentrations suggested an unusual accumulation of copper in chickens that consumed 16 microg copper/g diet. The molecular weight of lysyl oxidase was also estimated using matrix-assisted laser desorption ionization/time-of-flight/mass spectrometry (MALDI/TOF/MS). A novel aspect of these measurements was estimation of protein mass directly from the surface of chick tendons and aortae. Whether copper deficiency (0 added copper) or copper supplementation (16 microg copper/g of diet) caused changes in the molecular weight of protein(s) in tendon corresponding to lysyl oxidase was addressed. The average molecular weight of the peak corresponding to lysyl oxidase in tendon and aorta from copper-deficient birds was 28,386 Da +/- 86, whereas the average molecular weight of corresponding protein in tendon from copper-supplemented birds was 28,639 Da +/- 122. We propose that the shift in molecular weight is due in part to copper binding and the formation of lysyl tyrosyl quinone, the cofactor at the active site of lysyl oxidase.

Animals↗
PubMed1998

The influence of types of character on processing background information in narrative discourse.

The background sentence The air was cold and clammy depicts setting information which may or may not be of significance to a given character in a narrative. We tested the hypothesis that such information is processed with respect to the main character in a narrative rather than with respect to a secondary character. In Experiment 1, subjects making attributions of awareness of such background states were more likely to attribute such awareness to main than to secondary characters. In Experiment 2, using self-paced reading, we showed that such information is more important for main than for secondary characters during reading. Thus, unattached background information is processed with respect to main characters. This bias provides a source of control over the processing necessary to establish a coherent representation during the reading of narratives. Experiment 3 eliminated the possibility that the effects were due to generally shallower processing of sentences centered on secondary characters.

Adult↗
PubMed1994

The rad16 gene of Schizosaccharomyces pombe: a homolog of the RAD1 gene of Saccharomyces cerevisiae.

The rad10, rad16, rad20, and swi9 mutants of the fission yeast Schizosaccharomyces pombe, isolated by their radiation sensitivity or abnormal mating-type switching, have been shown previously to be allelic. We have cloned DNA correcting the UV sensitivity or mating-type switching phenotype of these mutants and shown that the correcting DNA is encompassed in a single open reading frame. The gene, which we will refer to as rad16, is approximately 3 kb in length, contains seven introns, and encodes a protein of 892 amino acids. It is not essential for viability of S. pombe. The predicted protein is the homolog of the Saccharomyces cerevisiae RAD1 protein, which is involved in an early step in excision-repair of UV damage from DNA. The approximately 30% sequence identity between the predicted proteins from the two yeasts is distributed throughout the protein. Two-hybrid experiments indicate a strong protein-protein interaction between the products of the rad16 and swi10 genes of S. pombe, which mirrors that reported for RAD1 and RAD10 in S. cerevisiae. We have identified the mutations in the four alleles of rad16. They mapped to the N-terminal (rad10), central (rad20), and C-terminal (rad16 and swi9) regions. The rad10 and rad20 mutations are in the splice donor sequences of introns 2 and 4, respectively. The plasmid correcting the UV sensitivity of the rad20 mutation was missing the sequence corresponding to the 335 N-terminal amino acids of the predicted protein. Neither smaller nor larger truncations were, however, able to correct its UV sensitivity.

Amino Acid Sequence↗
PubMed1989

The children's self-report questionnaire: factor score age trends and gender differences.

Age trends and gender differences in a normative sample of 1,676 children (6- to 13-years) were explored with the use of scores obtained from the Children's Self-Report Questionnaire (SRQ). Several interesting trends emerged. Boys scored higher than girls on Conduct Problems, and girls scored higher than boys on dimensions labeled Worry and Sensitive-Emotional. Scores on other SRQ factors exhibited orderly increases or decreases across age groups. These trends are discussed in an attempt to clarify behavioral cognitive and affective age appropriate norms and are cautiously interpreted within a developmental framework. The identification of age and gender trends are a necessary step in the development of a diagnostic instrument intended for use with children. The age and gender trends observed lend additional support to the validity of the SRQ.

Affective Symptoms↗
PubMed1989

Diagnostic interviewing with children: the use and reliability of the diagnostic coding form.

There have been few attempts to standardize assessment methods in Child Psychiatry. This paper describes a semi-structured approach to diagnostic interviewing of the child. Thirty-four children six to 13 years of age, and their parents, were interviewed two weeks apart by two different psychiatrists. A diagnostic coding form consisting of 29 clinical symptom items, eight summary items, and nine positive health ratings was used. Three diagnostic items were also included: "severity of clinical condition," "probability of disorder," and "adjustment status." Twelve of the Time 2 interviews with the child and parent were videotaped and rated by three different psychiatrists. Results indicated that summary items had higher reliability than individual symptom items and the three diagnostic items had the highest reliability, suggesting reliability is better for broad classes of behaviour. Interrater reliability was higher for the face-to-face rating than videotaped ratings. This suggests first that face-to-face interviews are reasonably stable over a two week period and second, since videotaped ratings had lowest reliability on items that depended on inferences about the child's feedlings, an important source of variance in assessment may be the clinician's ability to empathize with the child and draw inferences about internal feeling-states. It was concluded that this interview schedule can be a part of routine clinical practice. It ensures a reasonably standard, yet flexible and reliable approach to diagnostic interviewing.

Adaptation, Psychological↗
PubMed1986

Prevalence of speech and language disorders in 5-year-old kindergarten children in the Ottawa-Carleton region.

A representative sample of 5-year-old kindergarten children was assessed for speech and/or language disorder. Of the 1,655 children tested, 180 were identified as having speech or language impairment. It is estimated that within the total reference population, between 16.2% and 21.8% would show some impairment; for the boys, the rate would be 15.5% to 20.7% and for the girls, between 19.1% and 25.1%. Most of these children would show some language impairment as opposed to speech problems only. Approximately 36% of the identified boys and 30% of the girls would have speech problems only, the remainder having speech and language problems or language problems only. Followup studies of these children are needed to ascertain their outcome and language status in middle childhood.

Articulation Disorders↗
PubMed1981

Developmental changes in composition of rat milk: trace elements, minerals, protein, carbohydrate and fat.

The concentrations of iron, copper, zinc, manganese, calcium and magnesium, as well as protein, carbohydrate and fat, were analyzed in rat milk during the course of lactation in rats fed a purified diet. As serial milking has been demonstrated to affect milk composition (1), lactating rats were milked only once at various times from days 0 to 28 after parturition. Concentration of iron decreased rapidly from 9 to 5 micrograms/ml during the 1st week of lactation and changed little thereafter. Similarly, copper concentration decreased considerably in early lactation, from 9 to 2 micrograms/ml, but then remained constant. Zinc concentration did not decrease during the 1st week of lactation, but dropped from 14 micrograms/ml in the 2nd week of lactation to 8-10 micrograms/ml in mature milk. Manganese was unique as its concentration decreased during the early days of lactation, from 0.3 to 0.1 microgram/ml, with a subsequent rise in late lactation back to 0.3 microgram/ml. Calcium and magnesium concentrations increased somewhat in early lactation and decreased slightly in later lactation, but the changes were fairly small as compared to the trace elements. Developmental patterns for protein, carbohydrate and fat were not very pronounced, although protein and carbohydrate increased somewhat in early lactation and later decreased. These data demonstrate that the nutrient intake of the suckling changes markedly during the early neonatal period. These changes should be taken into account in evaluating data on the trace element composition of tissues of suckling rats.

Animals↗