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Biomedical subjects

M Wilson

Publications and source records attributed to M Wilson.

At least 163 records · Page 9Linked to original sources
PubMed2000

Injury-producing events among children in low-income communities: the role of community characteristics.

STUDY PURPOSE: Injury remains the leading cause of death in children aged 1 to 4 years. Past studies of determinants of injuries among young children have most often focused on the microlevel, examining characteristics of the child, parent, family, and home environments. We sought to determine whether and how selected neighborhood economic and physical characteristics within these low-income communities are related to differences in risk of events with injury-producing potential among infants and young children. METHODS: Our study used both individual-level data and information on the characteristics of the neighborhood of residence to describe the prevalence of events with injury-producing potential among infants and young children in three low-income communities in Baltimore City, Maryland. Our sample was 288 respondents who participated in a random household survey. Information on respondent (age, employment, and length of residence in the neighborhood) and neighborhood characteristics (average per capita income, rate of housing violations, and crime rate) were available. Methods of multilevel Poisson regression analysis were employed to identify which of these characteristics were associated with increased risk of experiencing an event with injury-producing potential in the month prior to the interview. RESULTS: Although all three communities were considered low income, considerable variation in neighborhood characteristics and 1-month prevalence rates of events with injury-producing potential were observed. Younger age of respondent and higher rates of housing violations were associated significantly with increased risk of a child under 5 years old in the household experiencing an event with injury-producing potential. CONCLUSIONS: Information on community characteristics was important to understanding the risks for injuries and could be used to develop community-based prevention interventions.

Adolescent↗
PubMed2000

Axial and total-body bone densitometry using a narrow-angle fan-beam.

We assessed a new dual-energy bone densitometer, the PRODIGY, that uses a narrow-angle fan-beam (4.5 degrees) oriented parallel to the longitudinal axis of the body (i.e., perpendicular to the usual orientation). High-resolution scans across the body can be stepped at 17 mm intervals. The energy-sensitive array detector uses cadmium zinc telluride, which allowed rapid photon counting. Spine and femur scans required 30 s, and total-body scans required 4-5 min; the dose was only 3.7 mrem and 0.04 mrem respectively, or about 5 to 10 times lower than conventional fan-beam densitometry. We found only a small influence of soft-tissue thickness on bone mineral density (BMD) results. There was also a small (+/- 1%) influence of height above the tabletop on BMD results. A software correction for object height allowed a first-order correction for the large magnification effects of position on bone mineral content (BMC) and area. Consequently, the results for BMC and area, as well as BMD, with PRODIGY corresponded closely to those obtained using the predecessor DPX densitometer, both in vitro and in vivo; there was a generally high correlation (r = 0.98-0.99) for BMD values. Spine and femur values for BMC, area and BMD averaged within 0.5% in vivo (n = 122), as did total-body BMC and BMD (n = 46). PRODIGY values for total-body lean tissue and fat also corresponded within 1% to DPX values. Regional and total-body BMD were measured with 0.5% precision in vitro and 1% precision in vivo. The new PRODIGY densitometer appears to combine the low dose and high accuracy of pencil-beam densitometry with the speed of fan-beam densitometers.

Absorptiometry, Photon↗
PubMed2000

Plant Species and Plant Incubation Conditions Influence Variability in Epiphytic Bacterial Population Size.

The influences of plant species and plant incubation conditions on the variability in bacterial population sizes among leaves were investigated in field and growth chamber studies. Pseudomonas syringae strains TLP2 and Cit7 were inoculated onto plants and population sizes were measured at intervals after inoculation. Total bacterial population sizes were also assessed in field studies. Levels of leaf-to-leaf variability in both P. syringae population size and bacterial community size differed significantly among plant species. For all plant species, variability among leaves in population sizes of inoculated bacteria was consistently greater than the leaf-to-leaf variability in numbers of total bacteria. Considering levels of variability in population size immediately prior to and following incubation under either wet or dry physical conditions, leaf-to-leaf variability in the population sizes of inoculated P. syringae strains increased significantly following incubation under dry, but not under wet, conditions. Measurements of leaf-to-leaf variability immediately prior to and following incubation were positively correlated regardless of whether the incubation was under wet or dry conditions, though the correlation was greater following dry incubation. These data provide insight into the biological and physical factors that may be important in generating variability in bacterial population sizes among leaves, and they have important implications for the design of appropriate strategies for sampling leaf surface microbial populations. </hea

Journal Article↗
PubMed2000

Suture closure of femoral arterial puncture sites after coronary angioplasty followed by same-day discharge.

BACKGROUND: The purpose of this study was to determine whether immediate suture closure of 8F femoral arterial puncture sites can facilitate same-day discharge after coronary angioplasty. METHODS AND RESULTS: After coronary angioplasty, 100 patients were randomly assigned to immediate sheath removal with the double-suture Prostar-Plus device or delayed sheath removal with application of a c-clamp. After suture closure, mobilization at 4 hours after sheath removal and discharge 4 hours later were planned. Patients treated with the c-clamp had sheaths removed 4 hours after percutaneous transluminal coronary angioplasty, were mobilized 6 hours later, and discharged the following day. Patients were assessed for groin complications at 8, 24, and 72 hours. Overall, patients who received suture closure were mobilized at 7.1 +/- 5.3 hours and discharged 11. 15 +/- 6.22 hours after sheath removal versus 15.49 +/- 3.9 hours and 21.9 +/- 3.8 hours for patients with the c-clamp (P <.001). Initial failure of the suture device occurred in 5 patients, with 1 requiring surgery for an entrapped device. After the procedure, patients with suture closure more frequently had an ooze of blood (55% vs 24%, P <.001) and a trend to more overt external bleeding (10% vs 2%, P = not significant). Hematomas were reported by 20% of patients in both groups at 72 hours. Overall, patients preferred the suture closure method of sheath removal when assessed by a simple questionnaire. An economic analysis by cost minimization demonstrated potential hospital cost saving. CONCLUSIONS: Suture closure of 8F arterial puncture sites can facilitate early mobilization and same-day discharge and is considered acceptable by more patients compared with application of the c-clamp. There is potential to realize cost savings with a strategy of same-day discharge.

Angioplasty, Balloon, Coronary↗
PubMed2000

Inhibition of mitosis and induction of apoptosis in MG63 human osteosarcoma-derived cells in vitro by surface proteins from Actinobacillus actinomycetemcomintans.

Gentle saline extraction releases a heterogeneous mixture of proteins associated with the cell surface of Actinobacillus actinomycetemcomintans, termed the surface protein fraction (SF). Some SF components are biologically active and may modulate cell behaviour in a manner of putative importance in the aetiology of periodontitis. To further characterize this activity, the ability of the SF to induce mitosis and apoptosis in MG63 cells was investigated. Cells were plated at 10(3)-10(4) cells/cm(2) and allowed to attach before culture in the serum-free medium in the presence of 25 microg/ml SF for 2-24 h. The apoptotic and mitotic figures present were counted and the results expressed as an apoptotic or mitotic index. The apoptotic and mitotic compartments were very small, but there was an inverse correlation between mitosis and apoptosis. In control experiments the mitotic was higher than the apoptotic index, whilst in the presence of SF this was reversed. These results were confirmed using in situ end-labelling. SF, therefore, may stimulate apoptotic, but inhibit mitotic, activity in MG63 cells. This raises the possibility that components of SF might induce subtle changes in the balance between apoptosis and mitosis, which, in turn, could contribute to the progression of periodontitis.

Aggregatibacter actinomycetemcomitans↗
PubMed2000

Trajectory encoding in the hippocampus and entorhinal cortex.

We recorded from single neurons in the hippocampus and entorhinal cortex (EC) of rats to investigate the role of these structures in navigation and memory representation. Our results revealed two novel phenomena: first, many cells in CA1 and the EC fired at significantly different rates when the animal was in the same position depending on where the animal had come from or where it was going. Second, cells in deep layers of the EC, the targets of hippocampal outputs, appeared to represent the similarities between locations on spatially distinct trajectories through the environment. Our findings suggest that the hippocampus represents the animal's position in the context of a trajectory through space and that the EC represents regularities across different trajectories that could allow for generalization across experiences.

Algorithms↗
PubMed2000

Diffuse component of solar ultraviolet radiation in tree shade.

The first set of quantitative data of diffuse erythemal UV and UV-A radiation in tree shade at a sub-tropical Southern Hemisphere latitude is presented. Over the summer, approximately 60% of the erythemal UV radiation in tree shade is due to the diffuse component. Similarly, approximately 56% of the UV-A radiation in tree shade is due to the diffuse component. In tree shade these diffuse UV percentages are relatively constant from the morning to noon to afternoon periods. In comparison, in full sun, there is a decrease in the percentage of diffuse UV from morning to noon to afternoon. The exposures to diffuse UV on a horizontal plane in tree shade between 9:00 EST and 15:00 EST are of the order of 4 MED (minimum erythemal dose) and 14 J cm(-2) for erythemal UV and UV-A, respectively. The high diffuse UV component in the shade may result in high UV exposures not only to unprotected parts of the body on a horizontal plane, but also in equally high UV irradiances to parts of the body, including the eyes and face, that are not UV protected.

Diffusion↗
PubMed2000

Not quite right.

Explore the source record for details and available documents.

Child↗
PubMed2000

Developmental regulation of hippocampal excitatory synaptic transmission by metabotropic glutamate receptors.

The aims of this study were, to use agonists selective for the 3 mGlu receptor groups to identify developmental changes in their effects, and to assess the usefulness of proposed selective antagonists as pharmacological tools. Hippocampal slices (400 microm) were prepared from neonate (9 - 14 days) and young adult (5 - 7 weeks) Sprague-Dawley rats. Field excitatory postsynaptic potentials (fEPSP) were recorded from CA1. DHPG (100 microM), a group I agonist, produced a slowly developing enhancement of fEPSP slope in slices from adults. In slices from neonates, DHPG (75 microM) depressed fEPSP slope. DCG-IV (500 nM), a group II agonist, did not affect the fEPSP recorded from slices from adults whereas perfusion in neonate slices produced a sustained depression. The group III agonist L-AP4 (50 microM) was ineffective in adult slices but depressed fEPSP slope in slices prepared from neonates. DHPG-induced depression of fEPSP slope was inhibited by 4-CPG (400 microM), a group I antagonist, but was unaffected by MCCG (500 microM) and MAP4 (500 microM), group II and III receptor antagonists respectively. MCCG but not MAP4 antagonized the effects of DCG-IV with 4-CPG producing variable effects. The effect of L-AP4 was unaffected by MCCG, blocked by MAP4, and enhanced by 4-CPG. The results show that the effects of the agonists for all groups of mGlu receptors are developmentally regulated. Furthermore, MCCG and MAP4 behave as effective and selective antagonists for group II and group III mGlu receptors respectively, whereas the usefulness of 4-CPG as a group I antagonist may be limited.

Animals↗
PubMed2000

Anti-adhesive and antibacterial properties of a proprietary denture cleanser.

The antimicrobial efficacy and anti-adhesive attributes of a proprietary denture cleanser were evaluated. To determine cleanser antimicrobial efficacy, Streptococcus mutans was grown on denture acrylic strips which were then exposed to the cleanser. To evaluate anti-adhesive efficacy, the strips were treated with the cleanser and then placed in the Strep. mutans suspension. Following incubation, adhered bacteria were removed and enumerated by viable counting. Treated denture acrylic plates were also placed in a parallel-plate flow chamber and then exposed to Strep. oralis. Images of adhered bacteria were analysed to determine biofilm coverage. Biofilm removal force was quantified by increasing the flow rate between the acrylic plates. The cleanser exhibited a 100% kill against Strep. mutans adhered to the acrylic surface, and inhibited attachment of cells by 66%. The flow chamber study found that cleanser-treated denture acrylic allowed the formation of a multilayer biofilm which was easily removed by a slight increase in flow rate.

Bacterial Adhesion↗
PubMed2000

Huntington's disease: neurological assessment of potential gene carriers presenting for predictive DNA testing.

One hundred and fifty-six potential gene carriers who were 50% 'at risk' of inheriting the Huntington's disease (HD) mutation, and who presented for predictive testing, underwent neurological assessment before their gene status had been determined. The association between pre-gene result symptoms and minimal neurological signs (insufficient for diagnosis in their own right) and subsequent gene status was determined. Of these, 38% tested positive for the HD mutation. Fifty-one individuals had minor neurological signs. After exclusions, 61% of gene-positive patients had minor neurological signs, whereas only 8% testing gene negative had signs. Minimal chorea observed in the toes and feet with the subject supine, and the patient being stressed by a mental task carried 96% specificity and 86% positive predictive value for gene-positive status. Neurological symptoms did not distinguish gene status, but behavioural and cognitive symptoms were more often reported by the gene-positive group. Although an 'at-risk' individual may receive a gene-positive result, neurological examination remains the most accessible, reliable and cost effective means of determining clinical disease onset.

Adult↗
PubMed2000

Values and beliefs of vegetarians and omnivores.

Following the claim by some anthropologists and sociologists that 1 symbolic meaning of meat is a preference for hierarchical domination (C. J. Adams, 1990; N. Fiddes, 1989; D. D. Heisley, 1990; J. Twigg, 1983), the authors compared the values and beliefs of vegetarians and omnivores in 2 studies conducted in New Zealand. They compared the full range of vegetarians and omnivores on right-wing authoritarianism, social dominance orientation, human values, and consumption values. The participants tending toward omnivorism differed from those leaning toward veganism and vegetarianism in 2 principal ways: The omnivores (a) were more likely to endorse hierarchical domination and (b) placed less importance on emotional states. Accordingly, the acceptance or rejection of meat co-varied with the acceptance or rejection of the values associated with meat; that finding suggests that individuals consume meat and embrace its symbolism in ways consistent with their self-definitions.

Authoritarianism↗
PubMed2000

Personal exposure distribution of solar erythemal ultraviolet radiation in tree shade over summer.

The personal radiant exposure distribution of solar erythemal UV in tree shade for an upright posture was measured, with measurements over the whole summer for a total of 17 trees. For each tree, the personal radiant exposure distribution was measured for both the morning and afternoon periods. The exposure ratios averaged over all the trees and over the morning and afternoon periods ranged from 0.16 to 0.49 for the different anatomical sites. A numerical model was employed to estimate the UV radiant exposure to humans in tree shade over the entire summer. The body sites with the higher exposure ratios in the tree shade were the vertex of the head, shoulders and forearms with radiant exposures over the summer of 1300 MED to the vertex of the head and 1100 MED to the shoulders and forearms. These radiant exposures in the shade are substantially higher than the ambient erythemal UV measured in full sun on a horizontal plane over a full summer at a more temperate northern hemisphere latitude. The average radiant exposures per day to each anatomical site for a complete day in the tree shade ranged from 4.6 to 14.6 MED. This research has provided new data that is essential to quantify human UV exposure during outdoor activities.

Australia↗
PubMed2000

Voids in the H-bonded network of water and their manifestation in the structure factor

The main peak of the oxygen-oxygen structure factor S(OO)(Q) of liquid water shows an unusual doublet structure. The low-Q feature of the doublet shifts appreciably with pressure, between limits which correspond to the position of the first peak in the low- and high-density forms of amorphous ice. This pressure dependence has been cited as evidence of polyamorphism in water. It is shown that this feature is analogous to the "prepeak," or "first-sharp-diffraction peak" which is well known in network-forming ionic liquids, like SiO2, and that its position is determined by the nearest-neighbor separation of voids in the spatial distribution of oxygen atoms.

Journal Article↗
PubMed2000

The osmotic swelling characteristics of cardiac valve prostheses.

Several types of mechanical cardiac prostheses have been constructed with Delrin occluders, a material that is subject to osmotic swelling. The leaftets are designed to expand to specific tolerances when immersed in blood. The synthetic blood analogs commonly used in vitro contain hydrophilic compounds that can alter the osmotic expansion of the Delrin occluders. A static leak test chamber was employed to illustrate the effects of various test fluids on the sustained regurgitation phase of Delrin valves.

Equipment Failure Analysis↗