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Biomedical subjects

T Morris

Publications and source records attributed to T Morris.

At least 55 records · Page 3Linked to original sources
PubMed1994

Incisal overjet as an outcome measure in unilateral cleft lip and palate management.

The Goslon Yardstick is a clinical tool used to rank dental study casts of persons with cleft lip and palate in the late mixed or early permanent dentition into one of five categories. It has been successfully used to investigate the outcomes of the surgical treatment of these anomalies as well as the effects of these deformities on untreated individuals. In this study, 40 study casts ranked by the Goslon Yardstick were digitized using a reflex metrograph. The overjet, overbite, and incisal angulation, and the crossbites of the canines and molars were calculated for each of the sets of casts. Multiple regression analysis was used to determine the predictive value of these variables upon the Goslon scores. The overjet was found to explain 87% of the variance of the Goslon score (p < .0001). No other component had a significant predictive value. The range of overjet associated with the different Goslon scores was calculated from the regression equation. In conclusion, the advantages of using overjet as an indicator of outcome as an alternative to the Goslon Yardstick were discussed.

Child↗
PubMed1993

Formation of large deletions by illegitimate recombination in the HPRT gene of primary human fibroblasts.

HPRT gene mutants were isolated from untreated and x-irradiated cultures of primary human fibroblasts, and mutants carrying large deletions were identified. The breakpoints of the deletions were mapped by methods based on the polymerase chain reaction, and the deletion junctions of four different mutants were sequenced. Alu repeats were associated with one end of three of these junctions, but in each case repeat sequences were not found at the other end. Sequence features found at the deletion breakpoints included in particular short direct and inverted repeats, which may mispair to promote illegitimate recombination. One mutant had additional bases inserted at the deletion junction; these bases formed a direct repeat with a sequence immediately adjacent to the junction, suggesting a mechanism of templated repair of broken DNA in deletion formation.

Base Sequence↗
PubMed1993

Analysis of large deletions in the HPRT gene of primary human fibroblasts using the polymerase chain reaction.

Spontaneous and X-ray-induced mutants of the HPRT gene were isolated from two primary human fibroblast lines. The limited life-span of the mutants restricted the use of methods requiring large quantities of DNA, and the polymerase chain reaction (PCR) was used in particular to check for the presence of multiple genomic sites in mutant analysis. Robust PCR primers were designed to amplify sites of up to 1 kb, mostly with 1-kb spacings between sites, over the entire 56-kb HPRT gene region. Using PCR, large deletions were found in 43% of independent X-ray-induced mutants, and their breakpoints were localized where these fell within the gene. Anonymous DNA sites in the Xq26 chromosomal region containing HPRT (covering > or = 1.5 Mb) were also amplified by PCR to assess codeletion with HPRT; sites up to 1 Mb distal to the gene (DXS86, DXS10) were codeleted in some mutants, but no mutant was found with loss of a proximal site (DXS79).

Base Sequence↗
PubMed1993

Rhinometry and open-mouth posture in young children.

A biracial sample of 348 elementary school children who were in the first grade were assessed for open-mouth posture (OMP) in the natural environment. In addition, rhinometry was performed on 296 of the children. Means were computed for percent OMP and cross-sectional nasal airway. Results indicated that, in general, these children exhibited relatively high rates of OMP. Boys displayed significantly greater OMP than girls, and black children showed significantly larger cross-sectional nasal areas than white children. A significant correlation between OMP and nasal area only was evident for children exhibiting OMP during more than 80% of the observation intervals. The implications of the findings were discussed.

Analysis of Variance↗
PubMed1993

High-resolution cytogenetic analysis of X-ray induced mutations of the HPRT gene of primary human fibroblasts.

We report cytogenetic analysis of X-ray induced mutants of the HPRT gene isolated from a primary human fibroblast line. The mutants were shown previously by molecular analysis to have total or partial HPRT gene deletions. Detailed analysis of the chromosomal region containing HPRT (the cytogenetic band Xq26) identified Xq26 aberrations in five of five total HPRT gene deletions but failed to detect any changes in two of two partial gene deletions. Four microdeletions were verified and quantified by a method termed the band ratio, which compares the distance between bands encompassing Xq26 and an adjacent X-chromosome region in elongated chromosomes. These measurements were supported by the presence or absence of the sub-band Xq26.2. One total HPRT gene deletion was also associated with an X;11 translocation involving band Xq26. The data strengthen earlier findings on the tolerance of the Xq26 region to large genetic changes (> 1 Mb), but also indicate that some mutations are more complex than simple deletion of DNA sequence.

Cells, Cultured↗
PubMed1992

The "Torrstick": a ruler calibrated in millimeters of mercury for measurement of hydrostatic pressure.

We have designed and constructed a ruler ("Torrstick") calibrated in millimeters of mercury for the measurement of hydrostatic pressure differences. Marks are placed on a measuring stick every 1.34 cm, to afford the best compromise between a column of 0.9% saline solution and a column of blood. Several uses for this ruler are proposed, including the measurement of central venous pressure.

Blood Pressure Determination↗
PubMed1992

Rapid screening for deletion mutations in the hprt gene using the polymerase chain reaction: X-ray and alpha-particle mutant spectra.

Conditions were devised for the isolation of DNA from single-mutant colonies on dishes, to give reproducible results in the polymerase chain reaction (PCR). Primers for 3 exons of the hamster hprt gene were used in a multiplex reaction to show rapidly whether the mutants carried deletions at these sites. 138 independent mutants were screened in total, some spontaneous and others induced by X-rays or by alpha-particles from plutonium-238. Few deletions were found among the spontaneous set, while 'total' gene deletions formed about half the mutants found after irradiation. At equitoxic doses, little difference in mutant spectrum was found for the X-ray set compared to the alpha-particle set. This rapid technique should be applicable to many instances of comparative mutagenesis.

Alpha Particles↗
PubMed1991

Complete heart block and severe aortic incompetence in relapsing polychondritis: clinicopathologic findings.

We describe a patient with relapsing polychondritis who developed fatal cardiac involvement comprising complete heart block, acute aortic incompetence, and cardiovascular collapse. Pathologic studies showed fibrosis of the cardiac conducting system and necrotizing inflammation of the aortic valve, features not previously described in relapsing polychondritis, as well as evidence of coronary artery vasculitis.

Adult↗
PubMed1990

Localization of deletion breakpoints in radiation-induced mutants of the hprt gene in hamster cells.

DNA was analysed from a large set of hamster hprt gene mutants, some induced by ionising radiations and others occurring naturally, to identify those with large alterations in part of the gene. DNA from these mutants was restricted further with different endonucleases and probed to establish the patterns of restriction fragments remaining. Of 15 mutants characterized, one showed a duplication of part of the 5' end of the gene, and the remainder showed deletions of various sizes. It was possible to approximately locate the breakpoints of the deletions by comparison of fragment patterns to a recently-established map of the hamster gene. The relatively small number of mutants examined precludes rigorous analysis of the distribution of breakpoints in the hprt gene, but taken with other recent studies of deletion mutagenesis it is suggested that non-random induction or selection of this type of mutation may occur.

Alpha Particles↗
PubMed1988

Psychological response to cancer diagnosis--II. Evidence for coping styles (coping styles and cancer diagnosis).

One hundred and seventy-eight newly diagnosed patients with breast cancer, non-Hodgkin's or Hodgkin's lymphoma were studied with respect to their cognitive responses to cancer diagnosis. These were examined in relation to anxiety, depression and health locus of control as well as to clinical-pathological variables. Data analysis of cognitive responses alone did not confirm the existence of mutually exclusive categories of response. Analysis of cognitive responses and the other psychological variables combined, however, revealed that four broad coping 'styles' could be delineated: 'positive/confronting', 'fatalistic', 'hopeless-helpless' and 'denial/avoidance', which corresponded to our previously described categories. Lower psychological morbidity was associated with a positive/confronting response to diagnosis and with high internal locus of control, while higher anxiety and depression scores were associated with a hopeless-helpless response to diagnosis and with low internal locus of control. The evidence for coping 'styles' is discussed as well as the implications of the results for the psychological management of cancer patients.

Adaptation, Psychological↗
PubMed1987

The effect of the respiratory cycle on mediastinal and lung dimensions in Hodgkin's disease. Implications for radiotherapy gated to respiration.

Changes in mediastinal and lung dimensions during respiration were studied to assess the potential of radiotherapy gated to respiration to minimize normal tissue irradiation. Twelve patients with mediastinal Hodgkin's disease were assessed using chest radiographs and thoracic computed tomography (CT) scans both during quiet breathing and at maximum inspiration in the standing, supine, and prone positions. A simple measure of the bulk of mediastinal disease, the ratio of the width of mediastinal mass to thoracic diameter, was determined from posteroanterior (PA) chest radiographs. The volumes of mediastinum, irradiated and protected lung if anteroposterior (AP) and PA mantle fields were used were determined from sequential thoracic CT scans and three-dimensional treatment planning and compared at quiet breathing and deep inspiration. The mediastinal width to thoracic diameter ratio decreased from quiet breathing to deep inspiration an average of 3%, 9%, and 11% for the standing, supine, and prone positions, respectively. Lung volumes as measured from the thoracic CT scans showed that on average, 8% more lung was protected at deep inspiration than at quiet breathing, independent of treatment position. The maximum increase in the percentage of protected lung from quiet breathing to deep inspiration was seen in patients with extensive mediastinal adenopathy suggesting that radiotherapy gated to respiration may be most advantageous in the subset of patients.

Hodgkin Disease↗