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Biomedical subjects

R A Armstrong

Publications and source records attributed to R A Armstrong.

At least 55 records · Page 3Linked to original sources
PubMed2000

The minor oral surgery outcome scale: a multi-attribute patient-derived outcome measure.

PURPOSE: The purpose of this study was to produce a clinically useful, patient-derived, minor oral surgery outcome scale. PATIENTS AND METHODS: Seventy-seven consecutive patients scheduled for minor oral surgery were interviewed using semistructured interview techniques to identify those areas of life (domains) that patients believed will be affected by minor oral surgery. These interviews were analyzed by a multidisciplinary panel and a scale based on 5 domains, each with 4 outcome statements was constructed. The domains and outcome statements were weighted in terms of importance by a further consecutive sample of 100 patients using resource allocation and visual analog tasks. An additive mathematical formula was applied to the mean weights for each domain and outcome states to produce the final weighted scale. RESULTS: Five domains were identified from the interviews and weighted according to their order of importance (0 to 100 scale; 0 = least important). These were general health and well-being (24.6); impact on home/social life (20.8); health and comfort of the mouth, teeth, and gums (20.0); appearance (18.8); and impact on job/studies (15.8). CONCLUSION: A clinically applicable, multi-attribute outcome scale has been produced that takes into account all determinants of health outcome as perceived by the patient in the context of minor oral surgery. It is completed by selecting a weighted statement from each domain, the sum of which constitutes the patient's health state utility score. The scale has potentially extensive application to both clinical care and research.

Adolescent↗
PubMed2000

Visual function and subjective quality of life compared in subjects with acquired macular disease.

PURPOSE: To determine the objective measures of visual function that are most relevant to subjective quality of vision and perceived reading ability in patients with acquired macular disease. METHODS: Twenty-eight patients with macular disease underwent a comprehensive assessment of visual function. The patients also completed a vision-related quality-of-life questionnaire that included a section of general questions about perceived visual performance and a section with specific questions on reading. RESULTS: Results of all tests of vision correlated highly with reported vision-related quality-of-life impairment. Low-contrast tests explained most of the variance in self-reported problems with reading. Text-reading speed correlated highly with overall concern about vision. CONCLUSIONS: Reading performance is strongly associated with vision-related quality of life. High-contrast distance acuity is not the only relevant measure of visual function in relation to the perceived visual performance of a patient with macular disease. The results suggest the importance of print contrast, even over print size, in reading performance in patients with acquired macular disease.

Adult↗
PubMed2000

An introduction to analysis of variance (ANOVA) with special reference to data from clinical experiments in optometry.

This article is aimed primarily at eye care practitioners who are undertaking advanced clinical research, and who wish to apply analysis of variance (ANOVA) to their data. ANOVA is a data analysis method of great utility and flexibility. This article describes why and how ANOVA was developed, the basic logic which underlies the method and the assumptions that the method makes for it to be validly applied to data from clinical experiments in optometry. The application of the method to the analysis of a simple data set is then described. In addition, the methods available for making planned comparisons between treatment means and for making post hoc tests are evaluated. The problem of determining the number of replicates or patients required in a given experimental situation is also discussed.

Analysis of Variance↗
PubMed2000

The microbiology of the eye.

Infection of the external structures of the eye is one of the commonest types of eye disease worldwide. In addition, although relatively impermeable to microorganisms, infection within the eye can result from trauma, surgery or systemic disease. This article reviews the general biology of viruses, bacteria, fungi and protozoa and the major ocular infections that they cause. In addition, the effectiveness of the various antimicrobial agents in controlling ocular disease is discussed. Because of changes in the normal ocular flora, continuous monitoring of the microbiology of the eye will continue to be important in predicting future types of eye infection. Basic research is also needed into the interactions of microbes at the ocular surface. There is increasing microbial resistance to the antimicrobial agents used to treat ocular infections and hence, new antimicrobial agents will continue to be needed together with new methods of drug delivery to increase the effectiveness of existing antimicrobial agents.

Eye Infections↗
PubMed2000

Distribution of the cyanophyte Trichodesmium (Oscillatoriaceae) in the eastern Caribbean Sea: influence of the Orinoco River.

Orinoco River influence in the Caribbean Sea, characterized by high nutrient input, causes a decrease of Trichodesmium populations. The Caribbean Time Series (CaTS) station, south of Puerto Rico (17 degrees 36'N 67 degrees 00'W), was monitored for 25 months in order to observe the Trichodesmium abundance pattern and the presence of the river plume. In general, mean Trichodesmium abundance was higher at the surface and decreased with depth. The mean upper water column (surface to 20 m) abundance was 54.1 +/- 32.6 col/m3. Within the sampling period, abundance was highly variable (1-700 col/m3). Correlation between Trichodesmium abundance and wind speed (p=0.002), chlorophyll a concentration (p=0.001), nitrate (p=0.02) and silicate (p=0.003) concentrations were statistically significant. However, Trichodesmium abundance was not correlated with salinity (p=0.70), temperature (p=0.16) and seawater density (p=0.71) variations at CaTS. Eastern Caribbean regions highly influenced by the Orinoco River discharge were devoid of Trichodesmium colonies.

Cyanobacteria↗
PubMed1999

Clustering of cerebral cortical lesions in patients with corticobasal degeneration.

Clustering of ballooned neurons (BN) and tau positive neurons with inclusion bodies (tau+ neurons) was studied in the upper and lower laminae of the frontal, parietal and temporal cortex in 12 patients with corticobasal degeneration (CBD). In a significant proportion of brain areas examined, BN and tau+ neurons exhibited clustering with a regular distribution of clusters parallel to the pia mater. A regular pattern of clustering of BN and tau+ neurons was observed equally frequently in all cortical areas examined and in the upper and lower laminae. No significant correlations were observed between the cluster sizes of BN or tau+ neurons in the upper compared with the lower cortex or between the cluster sizes of BN and tau+ neurons. The results suggest that BN and tau+ neurons in CBD exhibit the same type of spatial pattern as lesions in Alzheimer's disease, Lewy body dementia and Pick's disease. The regular periodicity of the cerebral cortical lesions is consistent with the degeneration of the cortico-cortical projections in CBD.

Aged↗
PubMed1999

Do beta-amyloid (Abeta) deposits in patients with Alzheimer's disease and Down's syndrome grow according to the log-normal model?

The size frequency distributions of diffuse, primitive and classic beta-amyloid (Abeta) deposits were studied in single sections of cortical tissue from patients with Alzheimer's disease (AD) and Down's syndrome (DS) and compared with those predicted by the log-normal model. In a sample of brain regions, these size distributions were compared with those obtained by serial reconstruction through the tissue and the data used to adjust the size distributions obtained in single sections. The adjusted size distributions of the diffuse, primitive and classic deposits deviated significantly from a log-normal model in AD and DS, the greatest deviations from the model being observed in AD. More Abeta deposits were observed close to the mean and fewer in the larger size classes than predicted by the model. Hence, the growth of Abeta deposits in AD and DS does not strictly follow the log-normal model, deposits growing to within a more restricted size range than predicted. However, Abeta deposits grow to a larger size in DS compared with AD which may reflect differences in the mechanism of Abeta formation.

Adult↗
PubMed1999

Quantification of pathological lesions in the frontal and temporal lobe of ten patients diagnosed with Pick's disease.

The densities of Pick bodies (PB), Pick cells (PC), senile plaques (SP) and neurofibrillary tangles (NFT) in the frontal and temporal lobe were determined in ten patients diagnosed with Pick's disease (PD). The density of PB was significantly higher in the dentate gyrus granule cells compared with the cortex and the CA sectors of the hippocampus. Within the hippocampus, the highest densities of PB were observed in sector CA1. PC were absent in the dentate gyrus and no significant differences in PC density were observed in the remaining brain regions. With the exception of two patients, the densities of SP and NFT were low with no significant differences in mean densities between cortical regions. In the hippocampus, the density of NFT was greatest in sector CA1. PB and PC densities were positively correlated in the frontal cortex but no correlations were observed between the PD and AD lesions. A principal components analysis (PCA) of the neuropathological variables suggested that variations in the densities of SP in the frontal cortex, temporal cortex and hippocampus were the most important sources of heterogeneity within the patient group. Variations in the densities of PB and NFT in the temporal cortex and hippocampus were of secondary importance. In addition, the PCA suggested that two of the ten patients were atypical. One patient had a higher than average density of SP and one familial patient had a higher density of NFT but few SP.

Adult↗
PubMed1999

[Arg6,D-Trp7,9,NmePhe8]-substance P (6-11) activates JNK and induces apoptosis in small cell lung cancer cells via an oxidant-dependent mechanism.

[Arg6,D-Trp7,9,NmePhe8]-substance P (6-11) (antagonist G) is a novel class of anti-cancer agent that inhibits small-cell lung cancer (SCLC) cell growth in vitro and in vivo and is entering phase II clinical investigation for the treatment of SCLC. Although antagonist G blocks SCLC cell growth (IC50 = 24.5 +/- 1.5 and 38.5 +/- 1.5 microM for the H69 and H510 cell lines respectively), its exact mechanism of action is unclear. This study shows that antagonist G stimulates apoptosis as assessed by morphology (EC50 = 5.9 +/- 0.1 and 15.2 +/- 2.7 microM for the H69 and H510 cell lines respectively) and stimulates c-jun-N-terminal kinase (JNK) activity in SCLC cells (EC50 = 3.2 +/- 0.1 and 15.2 +/- 2.7 microM). This activity is neuropeptide-independent, but dependent on the generation of reactive oxygen species (ROS) and is inhibited by the free radical scavenger n-acetyl cysteine. Furthermore, antagonist G itself induces inflammation (59% increase in oedema volume compared to control) and potentiates (by 35-40%) bradykinin-induced oedema formation in vivo. In view of these results we show that, as well as acting as a 'broad-spectrum' neuropeptide antagonist, antagonist G stimulates basal G-protein activity in SCLC cell membranes (81 +/- 12% stimulation at 10 microM), thereby displaying a unique ability to stimulate certain signal transduction pathways by activating G-proteins. This novel activity may be instrumental for full anti-cancer activity in SCLC cells and may also account for antagonist G activity in non-neuropeptide-dependent cancers.

3T3 Cells↗
PubMed1999

Laminar distribution of pick bodies, pick cells and Alzheimer disease pathology in the frontal and temporal cortex in Pick's disease.

Lesions in Alzheimer's disease (AD) and dementia with Lewy bodies (DLB) have distinct laminar distributions in the cortex. The objective of the present study was to test the hypothesis that the lesions characteristic of Pick's disease (PD) and AD have distinctly different laminar distributions in cases of PD. Hence, the laminar distribution of Pick bodies (PB), Pick cells (PC), senile plaques (SP) and neurofibrillary tangles (NFT) was studied in the frontal and temporal cortex in nine patients with PD. In 57% of analyses of individual cortical areas, the density of PB was maximal in the upper cortex while in 25% of analyses, the distribution of PB was bimodal with density peaks in the upper and lower cortex. The density of PC was maximal in the lower cortex in 77% of analyses while a bimodal distribution was present in 5% of analyses. The density of NFT was maximal in the upper cortex in 50% of analyses, in the lower cortex in 15% of analyses, with a bimodal distribution in 4% of analyses. The density of SP did not vary significantly with cortical depth in 86% of analyses. The vertical densities of PB and PC were negatively correlated in 12/21 (57%) of brain areas. The maximum density of PB in the upper cortex was positively correlated with the maximum density of PC in the lower cortex. In 17/25 (68%) of brain areas, there was no significant correlation between the vertical densities of PB and NFT. The data suggest that the pathogenesis of PB may be related to that of the PC. In addition, although in many areas PB and NFT occur predominantly in the upper cortex, the two lesions appeared to affect different neuronal populations.

Adult↗
PubMed1998

Clustering of Pick bodies in patients with Pick's disease.

Clustering of Pick bodies (PB) was studied in the frontal and temporal lobe in 10 cases of Pick's disease (PD). Pick bodies exhibited clustering in 47/50 (94%) brain areas analysed. In 20/50 (40%) brain areas, PB were present in a single large cluster > or =6400 microm in diameter, in 27/50 (54%) PB occurred in smaller clusters (200-3200 microm in diameter) which exhibited a regular periodicity relative to the tissue boundary, in 1/50 (2%) there was a regular distribution of individual PB and in 2/50 (4%), PB were randomly distributed. Mean cluster size of the PB was greater in the dentate gyrus compared with the inferior temporal gyrus and lateral occipitotemporal gyrus. Mean cluster size of PB in a brain region was positively correlated with the mean density of PB. Hence, PB exhibit essentially the same spatial patterns as senile plaques and neurofibrillary tangles in Alzheimer's disease (AD) and Lewy bodies in Dementia with Lewy bodies (DLB).

Adult↗
PubMed1998

The spatial patterns of Lewy bodies, senile plaques, and neurofibrillary tangles in dementia with Lewy bodies.

The spatial patterns of Lewy bodies (LB), senile plaques (SP), and neurofibrillary tangles (NFT) were studied in ubiquitin-stained sections of the temporal lobe in cases of dementia with Lewy bodies (DLB), which varied in the degree of associated Alzheimer's disease (AD) pathology. In all patients, LB, SP, and NFT developed in clusters and in a significant proportion of brain areas, the clusters exhibited a regular periodicity parallel to the tissue boundary. In the lateral occipitotemporal gyrus (LOT) and parahippocampal gyrus (PHG), the clusters of LB were larger than those of the SP and NFT but in the hippocampus, clusters of the three lesions were of similar size. Mean cluster size of the LB, SP, and NFT was similar in cases of DLB with and without significant associated AD pathology. LB density was positively correlated with SP and NFT density in 42 and 17% of brain areas analyzed, respectively, while SP and NFT densities were positively correlated in 7% of brain areas. The data suggest that LB in DLB exhibit similar spatial patterns to SP and NFT in AD and that SP and NFT exhibit similar spatial patterns in DLB and AD. In addition, in some instances, clusters of LB appeared to be more closely related spatially to the clusters of SP than to NFT.

Aged↗
PubMed1998

Neural networks: a new technique for development of decision support systems in dentistry.

OBJECTIVES: To outline the key concepts of neural network based systems and to evaluate the potential applications of such systems in dentistry. DATA SOURCES: Published work on neural networks. CONCLUSIONS: Neural networks may initially seem complex and computer intensive, but actually integrate well with a clinical environment. Neural network expert systems may be trained with only clinical data and as such can be used where 'rule based' decision making is not possible. This is the case in many clinical situations. Neural networks may therefore become important decision making tools within dentistry and have applications both in improving clinical care and in maximizing the cost benefit of care.

Algorithms↗
PubMed1998

Spatial distribution of diffuse, primitive, and classic amyloid-beta deposits and blood vessels in the upper laminae of the frontal cortex in Alzheimer disease.

The spatial distribution of the diffuse, primitive, and classic amyloid-beta deposits was studied in the upper laminae of the superior frontal gyrus in cases of sporadic Alzheimer disease (AD). Amyloid-beta-stained tissue was counterstained with collagen IV to determine whether the spatial distribution of the amyloid-beta deposits along the cortex was related to blood vessels. In all patients, amyloid-beta deposits and blood vessels were aggregated into distinct clusters and in many patients, the clusters were distributed with a regular periodicity along the cortex. The clusters of diffuse and primitive deposits did not coincide with the clusters of blood vessels in most patients. However, the clusters of classic amyloid-beta deposits coincided with those of the large diameter (>10 microm) blood vessels in all patients and with clusters of small-diameter (< 10 microm) blood vessels in four patients. The data suggest that, of the amyloid-beta subtypes, the clusters of classic amyloid-beta deposits appear to be the most closely related to blood vessels and especially to the larger-diameter, vertically penetrating arterioles in the upper cortical laminae.

Aged↗
PubMed1997

beta-Amyloid (A beta) deposition in the medial temporal lobe of patients with dementia with Lewy bodies.

The distribution and density of diffuse, primitive and classic beta-amyloid (A beta) deposits in the medial temporal lobe (MTL) was studied in cases of dementia with Lewy bodies (DLB) with and without associated Alzheimer's disease (AD) and 15 cases of sporadic AD. In the 'pure' DLB cases, virtually no A beta deposits were observed in the CA regions of the hippocampus or dentate gyrus whereas deposits were distributed throughout the MTL in DLB/AD and AD cases. Densities of diffuse and primitive A beta deposits were similar in AD and DLB/AD cases but density was significantly reduced in the 'pure' DLB cases. The density of the classic deposits was significantly reduced in DLB cases with or without associated AD compared with AD cases. These results suggest that A beta deposition in the MTL in 'pure' DLB cases is similar to that of elderly non-demented patients while, with the exception of the classic deposits, A beta deposition in DLB/AD cases is similar to that in cases of AD alone.

Aged↗