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Biomedical subjects

C Lowe

Publications and source records attributed to C Lowe.

At least 19 recordsLinked to original sources
PubMed2006

Which orthodontic archwire sequence? A randomized clinical trial.

The aim of this study was to compare three orthodontic archwire sequences. One hundred and fifty-four 10- to 17-year-old patients were treated in three centres and randomly allocated to one of three groups: A = 0.016-inch nickel titanium (NiTi), 0.018 x 0.025-inch NiTi, and 0.019 x 0.025-inch stainless steel (SS); B = 0.016-inch NiTi, 0.016-inch SS, 0.020-inch SS, and 0.019 x 0.025-inch SS; and C = 0.016 x 0.022-inch copper (Cu) NiTi, 0.019 x 0.025-inch CuNiTi, and 0.019 x 0.025-inch SS. At each archwire change and for each arch, the patients completed discomfort scores on a seven-point Likert scale at 4 hours, 24 hours, 3 days, and 1 week. Time in days and the number of visits taken to reach a 0.019 x 0.025-inch SS working archwires were calculated. A periapical radiograph of the upper left central incisor was taken at the start of the treatment and after placement of the 0.019 x 0.025-inch SS wire so root resorption could be assessed. There were no statistically significant differences between archwire sequences A, B, or C for patient discomfort (P > 0.05) or root resorption (P = 0.58). The number of visits required to reach the working archwire was greater for sequence B than for A (P = 0.012) but this could not be explained by the increased number of archwires used in sequence B.

Adolescent↗
PubMed2006

Balance marks cognitive changes in old age because it reflects global brain atrophy and cerebro-arterial blood-flow.

In healthy old age biomarkers such as Balance robustly correlate with measures of mental abilities such as scores on tests of intelligence, reaction times and memory. A plausible explanation is that balance reflects general physiological fitness and so also neurophysiological integrity, but direct evidence is lacking. Brain scans measured age-associated loss of brain volume and cerebro-arterial blood flow (CBf) in 69 volunteers aged from 62 to 81 years who also took the Tinetti Balance test battery, 3 tests of fluid intelligence, 3 tests of decision speed and a memory test. Balance, but not atrophy or CBf, predicted intelligence test scores. Balance, atrophy, and CBf all independently predicted speed and memory scores but, after variance in atrophy and CBf had been considered, predictions from Balance were no longer significant. It appears that in these tests Balance marks cognitive performance in old age because it reflects gross age-related neurophysiological changes.

Aged↗
PubMed2005

Visuotactile temporal order judgments in ageing.

We report an experiment on the effects of ageing on crossmodal temporal perception. Young (mean age = 21.7 years) and old (mean age = 75.1 years) participants were presented with pairs of visual and vibrotactile stimuli to either hand and required to make unspeeded temporal order judgments (TOJs) regarding which sensory modality appeared to have been presented first. The stimulus onset asynchrony (SOA) between the two stimuli was varied using the method of constant stimuli. Temporal precision, as indexed by the just noticeable difference (JND), was better (i.e., JNDs were lower) when the stimuli were presented from different positions (M = 101 ms) rather than from the same position (M = 120 ms), as has been demonstrated previously. Additionally, older observers required more time (i.e., their JNDs were larger) to accurately perceive the temporal order (M = 131 ms) as compared to younger observers (M = 98 ms). Our results confirm that ageing deleteriously affects crossmodal temporal processing even when the spatial confound inherent in previous research has been ruled out.

Adult↗
PubMed2005

Vision and touch in ageing: crossmodal selective attention and visuotactile spatial interactions.

We investigated whether ageing affects crossmodal selective attention (the ability to focus on a relevant sensory modality and ignore an irrelevant modality) and the spatial constraints on such selective processing. Three groups of 24 participants were tested: Young (19-25 years), Young-Old (65-72 years) and Old-Old (76-92 years). The participants had to judge the elevation of vibrotactile targets (upper/index finger and lower/thumb), presented randomly to either hand while ignoring concurrent visual distractors. In a second task, the role of the target and distractor modalities was reversed. Crossmodal selective attention was assessed by comparing performance in the presence versus absence of distractors. Spatial constraints on selective attention were also investigated by comparing the effect of distractors presented on the same versus opposite side as the target. When attending to touch, the addition of visual distractors had a significantly larger effect on error rates in both of the older groups as compared to the Young group. This indicates that ageing has a detrimental effect on crossmodal selective attention. In all three age groups, performance was impaired when the target and distractor were presented at incongruent as compared to congruent elevations in both tasks. This congruency effect was modulated by the relative spatial location of the target and distractor in certain conditions for the Young and the Young-Old group. That is, participants in the two younger age groups found it harder to attend selectively to targets in one modality, when distractor stimuli came from the same side rather than from the opposite side. However, no significant spatial modulation was found in the Old-Old group. This suggests that ageing may also compromise spatial aspects of crossmodal selective attention.

Adult↗
PubMed2005

Relative preservation of 'animate' knowledge in an atypical presentation of herpes simplex virus encephalitis.

A comprehensive battery of neuropsychological tests designed to assess primary cognitive functions, including language and semantic memory, was given to MG, a patient with confirmed herpes simplex virus encephalitis. MG's initial jargon aphasia resolved over time to leave her with a mild phonological impairment. She had a very mild amnesia that was worse for verbal material and a category-specific impairment of semantic memory. This latter impairment resulted in a significant anomia that was worse for manmade/artefact items than for animate kinds. Her naming difficulties were associated with a mild impairment in comprehension that was not specific to category or feature type. MRI revealed a strongly asymmetric and atypical distribution of pathology in MG with the disease affecting the left medial temporal lobe, temporal pole, left frontotemporal and temporoparietal regions.

Amnesia↗
PubMed2004

The contribution of non-ocular response inhibition to visual inhibition of return.

Inhibition of return (IOR) refers to slowed responses to targets presented at the same location as a preceding stimulus. IOR is typically investigated using a cue-target design, in which subjects respond only to the second stimulus of a pair. In such tasks, the measurement of 'true' IOR may be confounded by the effect of non-ocular response inhibition, because the participant must suppress any tendency to respond (e.g. key press) to the first stimulus. This confound may be eliminated using a target-target design, in which responses are made to both stimuli. We assessed the contribution of non-ocular response inhibition to visual IOR, measured in a cue-target task, by testing participants on both cue-target and target-target detection tasks, with identical timings and stimuli. Significant IOR was obtained in both tasks but, at a stimulus onset asynchrony (SOA) of 1400 ms, IOR magnitude was significantly greater in the cue-target condition than in the target-target condition. However, at an SOA of 1800 ms, there was no significant difference in the magnitude of IOR between the two tasks. Thus, a proportion of the total IOR effect observed in visual cue-target tasks can be attributed to non-ocular response inhibition, but this process appears to decay more rapidly than does 'true' IOR, having dissipated by 1800 ms following cue onset.

Adolescent↗
PubMed2002

The development of multiplex simple sequence repeat (SSR) markers to complement distinctness, uniformity and stability testing of rape (Brassica napus L.) varieties.

To assess the potential of multiplex SSR markers for testing distinctness, uniformity and stability of rape (Brassica napus L.) varieties, we developed three multiplex SSR sets composed of five markers each. These were used to measure the extent of diversity within and between a set of ten varieties using a fluorescence-based semi-automated detection technology. Also, we evaluated the significance of any correlation between SSRs, pedigree and five of the morphological characters currently used for statutory distinctness, uniformity and stability testing of rape varieties. An assignment test was allowed to identify 99% of the plants examined, with the correct variety based on the analysis of 48 individual plants for each variety. Principal coordinate analysis confirmed that a high degree of separation between varieties could be achieved. Varieties were separated in three groups corresponding to winter, spring and forage types. These results suggested that it should be possible to select a set of markers for obtaining a suitable separation. Diversity within varieties varied considerably, according to the variety and the locus examined. No significant correlation was found between SSR and morphological data. However, genetic distances measured by SSRs were correlated to pedigree. These results suggested that SSRs could be used for pre-screening or grouping of existing and candidate varieties, allowing the number of varieties that need to be grown for comparison to be reduced. Multiplex SSR sets gave high-throughput reproducible results, thus reducing the costs of SSR assessment. Multiplex SSR sets are a promising way forward for complementing the current variety testing system in B. napus.

Brassica napus↗
PubMed2001

The relationship among dental status, nutrient intake, and nutritional status in older people.

Dental health status may influence nutrition. The objective of this part of the National Diet and Nutrition Survey was to assess if there is a relationship between dental status in people 65 years and older and intake of certain nutrients and any link between dental status and blood-derived values of key nutrients. Random national samples of independently living subjects and those living in institutions had dental examinations, interviews, four-day food diaries, and blood and urine analyzed. In the sample living independently, intakes of most nutrients were lower in edentate than dentate subjects. Intake of non-starch polysaccharides, protein, calcium, non-heme iron, niacin, and vitamin C was significantly lower in edentate subjects. People with 21 or more teeth consumed more of most nutrients, particularly of non-starch polysaccharide. This relationship in intake was not apparent in the hematological analysis. Plasma ascorbate and plasma retinol were the only analytes significantly associated with dental status.

Aged↗
PubMed2000

Alginate hydrogel microspheres and microcapsules prepared by spinning disk atomization.

Our spinning disk atomization (SDA) can, relative to other existing techniques, produce micron-sized particles with very narrow size distribution. The aim of this work is to present this technology for the production of alginate microspheres and microcapsules. We atomized and gelled aqueous alginate solutions into very narrowly dispersed microspheres with sizes ranging from 300 to 600 microm. Here, the interest is to produce, at high rate, particles of a given size with a narrow size distribution and also to show a new method of encapsulation using SDA. The viscosity and flow rate contributions in the drop formation is qualitatively analyzed to show how they affect droplet size. In addition, a technique for high degree of encapsulation is presented in which yeast is used as a model system. The production of yeast-loaded microspheres by SDA shows the potential of the technique for biotechnology applications.

Biocompatible Materials↗
PubMed2000

Patterns of cognitive ageing.

Neuroanatomical evidence suggests that normal ageing affects some brain areas, and the "local" functions they support, earlier and more severely than others. Changes appear to be especially marked in the hippocampus, temporal association and prefrontal cortex. Evidence from classical neuropsychological studies suggests that these brain areas are associated with memory and "executive" functions, respectively. We may, therefore, expect that tests purported to measure these functions may be disproportionately affected in old age and that there may be evidence for some separation of these functions even within neurologically normal populations. What we also know, however, is that measures reflecting general fluid ability also decline with increasing age, so any hypothesis relating to specific "local" deficits must acknowledge and account for any "globar" changes in performance. Volunteers (n = 162) aged between 60-80 years who had completed the Cattell and Cattell Culture Fair Intelligence Test (CCF) completed the Cambridge Automated Neuropsychological Test Battery (CANTAB). The CANTAB has been administered to several patient populations and tests from the battery have been shown to be sensitive to damage in both temporal and prefrontal areas (Owen et al., 1996). Results from the test battery showed that both the Paired Associate Learning and Spatial Recognition tests were the most sensitive to normal ageing even when CCF is accounted for. In contrast, this performance on the "executive" tests, shown to be sensitive to frontal lobe damage was not related to age, and CCF scores predicted performance on these tests. These results are discussed in relation to theories of cognitive ageing and patterns of change and in relation to several important methodological and theoretical considerations for the study of executive function.

Aged↗
PubMed2000

Synthesis of acrylate functional telechelic poly(lactic acid) oligomer by transesterification.

The controlled synthesis of low molecular weight (Mn from 700 to 10 000 g/mol) poly(lactic acid) (PLA) telechelic oligomers end-capped with acrylate groups by a one-step reaction was investigated. A transesterification reaction was carried out in solution with a Lewis acid titanium catalyst using a high molecular weight PLA and a low molar mass diacrylate. End-functionalization was demonstrated by proton NMR spectroscopy which was also used for quantitative analysis and number average molecular weight determination using the ratio between the acrylic chain ends to the main groups of poly(D,L-lactic acid). The formation of low molar mass oligomers from high molecular weight poly(lactic acid) was verified by gel permeation chromatography. Matrix-assisted laser desorption ionization time-of-flight mass spectrometry showed that the above oligomerization was accompanied by the formation of cyclic compounds. By these means the feasability of a simple transesterification for a controlled synthesis of telechelic oligomers with molecular mass being a function of the added amount of diacrylate has been demonstrated. The glass transition temperatures of the elaborated oligomers varied from -35 to -5 degrees C. Subsequent thermal crosslinking was performed using benzoyl peroxide which enabled the formation of amorphous networks with Tg's close to the body temperature of 40 degrees C. Upon storage in a humid atmosphere the initially fairly hard and brittle networks became, due to hydrolysis, progressively more flexible thus demonstrating the potential biodegradability of these materials.

Journal Article↗
PubMed2000

p53 intronic point mutation, aberrant splicing and telomeric associations in a case of B-chronic lymphocytic leukaemia.

We report a case of chronic lymphocytic leukaemia (CLL) with telomeric associations and a p53 intronic point mutation. Karyotypic analysis revealed clonal and non-clonal telomeric associations, accompanied by clonal cytogenetic abnormalities and also in isolation. The p53 mutation, which occurred at the invariant base pair -2 of the splice acceptor site in intron 7 resulted in the abolition of correct splicing of exon 7 to exon 8. Multiple aberrant splice products were characterized, all of which differed from wildtype in the DNA binding domain. Fluorescence in situ hybridization demonstrated that the clone retained two copies of the p53 gene and wild-type p53 transcript was detected on cloning of reverse transcriptase polymerase chain reaction (RT-PCR) product, indicating that one wild-type allele remained. However, a plasmid clone with correct splicing at the exon 7/8 boundary, but with a 21 bp deletion in exon 8, was also found at low frequency. This finding indicates clonal evolution, resulting in complete loss of wild-type p53. The intronic point mutation was not present in DNA extracted from cervical tissue indicating that it was a leukaemic phenomenon. This is the first case of an intronic point mutation to be reported in CLL. This mutation led to chaotic p53 expression and, interestingly, occurred in a case showing telomeric associations, a rare phenomenon in B-CLL.

Amino Acid Sequence↗
PubMed1998

Aryl sulfonamides as selective PDE4 inhibitors.

A series of novel selective phosphodiesterase 4 (PDE4) inhibitors has been developed which displays activity both in vitro and in vivo. These compounds possess good selectivity for the catalytic site of PDE4 over the high affinity Rolipram binding site. In vivo studies demonstrate a reduced propensity to display the emetic side effects which are commonly observed with PDE4 inhibitors.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1998

Test/re-test reliability of the CANTAB and ISPOCD neuropsychological batteries: theoretical and practical issues. Cambridge Neuropsychological Test Automated Battery. International Study of Post-Operative Cognitive Dysfunction.

Neuropsychological test batteries are repeatedly administered to evaluate changes over time or the effects of clinical interventions. Relationships between scores on different tests within batteries are also examined to test models for associations between functional deficits. These comparisons may be misleading unless Test/Re-test reliability for individual tests is satisfactory. Interpretations of repeated measurements also depend on the extent to which improvement with practice varies between tasks and between more and less able individuals. Test/Re-test correlations and practice effects for two neuropsychological test batteries (CANTAB, ISPOCD) and from laboratory tasks commonly used in cognitive assessments of older people were obtained from large groups of healthy elderly. Tests in neuropsychological batteries varied markedly in test/re-test reliability which, in some cases, fell below levels considered methodologically acceptable. Putative measures of 'frontal' or 'executive' function, in which performance may be markedly improved by abrupt discovery of an appropriate strategy, were especially likely to show low reliability. Most tests showed significant practice effects, and on some these are substantial enough to compromise comparisons on repeated testing. On a minority of tests practice effects were counter-intuitive, in that less able showed significantly more gains than more able individuals.

Aged↗