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Biomedical subjects

David Wilson

Publications and source records attributed to David Wilson.

At least 73 records · Page 4Linked to original sources
PubMed2003

Native and minimally oxidized low density lipoprotein depress smooth muscle matrix metalloproteinase levels.

Vascular lesion development is associated with an accumulation of extracellular matrix proteins within the vessel wall. Matrix metalloproteinases (MMPs) degrade these proteins. Conversely, oxidized low density lipoprotein (LDL) is implicated in atherogenesis through, amongst other cellular effects, a stimulation of the deposition of collagen within the vascular lesion. The present study investigated the potential for an interaction between oxidized LDL and MMP levels. Within the vessel wall fibroblasts, smooth muscle, endothelial and infiltrating cells have been reported to secrete MMPs into the extracellular space to effect remodeling of the extracellular matrix. A consequence of angioplasty and atherosclerotic disease is the loss of endothelial cells or endothelial function, respectively. We have investigated the effects of chronic incubation of cultured vascular smooth muscle cells from rabbit thoracic aorta with oxidized LDL and its influence on MMP levels in the extracellular space. Our data indicate that a low concentration of minimally oxidized LDL (0.005 mg/mL) significantly depressed the levels of MMP-2 and MMP-9 present in the culture medium. Native LDL exerted the same effect but exhibited reduced potency. The effects were not attributable to cytotoxicity exerted by the oxidized LDL. The reduction in MMP secretion into the extracellular medium was a result of decreased enzyme synthesis within the smooth muscle cell. Our results demonstrate that an important atherogenic moiety, oxidized LDL, can reduce MMP activity and hence has the potential to increase the deposition of extracellular matrix proteins within SMC-rich vascular lesions.

Animals↗
PubMed2003

Low matrix metalloproteinase levels precede vascular lesion formation in the JCR:LA-cp rat.

Clinically significant occlusive vascular lesions contain more extracellular matrix (ECM) proteins and lipid deposition than healthy vascular tissue. The events leading to this condition remain unresolved. One possibility is that ECM deposition may exceed ECM degradation which would contribute to the expansion of the vascular lesion. Utilizing lean (+/?) and insulin-resistant, corpulent (cp/cp) JCR:LA-cp rats, which are predisposed to develop vascular lesions, we have compared the matrix metalloproteinase (MMP) profile prior to the development of significant vascular lesions. Analysis of serum MMPs revealed that cp/cp rats have lower circulating levels than (+/?) controls. This is observed prior to the development of any noticeable atherosclerotic lesions. It also occurs as the hyperinsulinemia and insulin resistance is first developing in these rats. Female corpulent animals, which are less prone to develop vascular lesions, also exhibit a depressed serum MMP profile of a similar magnitude to their male counterparts. Primary vascular smooth muscle cells isolated from cp/cp animals also showed a reduction in secreted MMP compared with cells derived from +/? lean controls. We conclude that reduced MMP levels could lead to increased ECM accumulation and thus contribute to early vascular lesion formation.

Animals↗
PubMed2002

Psychological reactions to terrorist attacks: findings from the National Study of Americans' Reactions to September 11.

CONTEXT: The terrorist attacks of September 11, 2001, represent an unprecedented exposure to trauma in the United States. OBJECTIVES: To assess psychological symptom levels in the United States following the events of September 11 and to examine the association between postattack symptoms and a variety of indices of exposure to the events. DESIGN: Web-based epidemiological survey of a nationally representative cross-sectional sample using the Posttraumatic Stress Disorder (PTSD) Checklist and the Brief Symptom Inventory, administered 1 to 2 months following the attacks. SETTING AND PARTICIPANTS: Sample of 2273 adults, including oversamples of the New York, NY, and Washington, DC, metropolitan areas. MAIN OUTCOME MEASURES: Self-reports of the symptoms of PTSD and of clinically significant nonspecific psychological distress; adult reports of symptoms of distress among children living in their households. RESULTS: The prevalence of probable PTSD was significantly higher in the New York City metropolitan area (11.2%) than in Washington, DC (2.7%), other major metropolitan areas (3.6%), and the rest of the country (4.0%). A broader measure of clinically significant psychological distress suggests that overall distress levels across the country, however, were within expected ranges for a general community sample. In multivariate models, sex, age, direct exposure to the attacks, and the amount of time spent viewing TV coverage of the attacks on September 11 and the few days afterward were associated with PTSD symptom levels; sex, the number of hours of television coverage viewed, and an index of the content of that coverage were associated with the broader distress measure. More than 60% of adults in New York City households with children reported that 1 or more children were upset by the attacks. CONCLUSIONS: One to 2 months following the events of September 11, probable PTSD was associated with direct exposure to the terrorist attacks among adults, and the prevalence in the New York City metropolitan area was substantially higher than elsewhere in the country. However, overall distress levels in the country were within normal ranges. Further research should document the course of symptoms and recovery among adults following exposure to the events of September 11 and further specify the types and severity of distress in children.

Adolescent↗
PubMed2002

Solution structures of the cis- and trans-Pro30 isomers of a novel 38-residue toxin from the venom of Hadronyche Infensa sp. that contains a cystine-knot motif within its four disulfide bonds.

The primary sequence and three-dimensional structure of a novel peptide toxin isolated from the Australian funnel-web spider Hadronyche infensa sp. is reported. ACTX-Hi:OB4219 contains 38 amino acids, including eight-cysteine residues that form four disulfide bonds. The connectivities of these disulfide bonds were previously unknown but have been unambiguously determined in this study. Three of these disulfide bonds are arranged in an inhibitor cystine-knot (ICK) motif, which is observed in a range of other disulfide-rich peptide toxins. The motif incorporates an embedded ring in the structure formed by two of the disulfides and their connecting backbone segments penetrated by a third disulfide bond. Using NMR spectroscopy, we determined that despite the isolation of a single native homologous product by RP-HPLC, ACTX-Hi:OB4219 possesses two equally populated conformers in solution. These two conformers were determined to arise from cis/trans isomerization of the bond preceding Pro30. Full assignment of the NMR spectra for both conformers allowed for the calculation of their structures, revealing the presence of a triple-stranded antiparallel beta sheet consistent with the inhibitor cystine-knot (ICK) motif.

Amino Acid Sequence↗
PubMed2002

Prevalence of influenza immunisation in Australia and suggestions for future targeting of campaigns.

OBJECTIVES: Reports on the results of a national survey conducted in Australia, in 2000. The objectives were to determine national estimates of influenza vaccination coverage for each state and territory of Australia, to obtain information related to attitudes towards and influences on immunisation decisions and explain the factors involved with failure to immunise. METHOD: The survey was conducted using the Computer Assisted Telephone Interview (CATI) system. The overall participation rate for the survey was 88.6% and the final number of completed interviews across Australia was n = 10,505. RESULTS: Two target groups, those aged 65 years and over and those "at risk" of influenza aged between 40 and 64 years were defined. The overall immunisation rates in these two groups were 74% and 32% resp. The rate of immunisation among females generally exceeded that of males. A multivariate model provided the best joint set of explanatory variables for not getting immunised. These include sex, income, general practitioner recommendation, and general perceptions regarding the influenza injection. CONCLUSION: This study identified important issues in the decisions of people to immunise. It also highlighted the need to target the findings in effective immunisation policies and strategies to improve health outcomes for those at risk of adverse influenza events.

Adult↗
PubMed2002

Rethinking and rescoring the SF-12.

OBJECTIVES: To derive and assess the validity of an Australian version of the SF-12 quality-of-life questionnaire. METHODS: Using regression methods and structural equation modelling to obtain item weights, an Australian version of the SF-12 was derived from Australian population survey data and compared to the existing United States (US) SF-12 variable set. RESULTS: The Australian version of the SF-12 explained 94% of the variation for physical components summary (PCS) and the mental components summary (MCS) of the SF-36 questionnaire. There was high level of agreement on the MCS and PCS summary scores between both versions of the SF-12 and the SF-36. CONCLUSIONS: Although it is possible to derive a valid Australian version of the SF-12 it is concluded the US version of the SF-12 be used for reasons of international comparability, but using item weights derived from structural equation modelling.

Adolescent↗
PubMed2002

Experimental forward mandibular displacement in sheep.

In order to investigate growth modifications of the temporomandibular joint (TMJ) during dentofacial orthopaedic treatment, specific functional appliances have been used experimentally to prompt the mandible into a protrusive position in various animal models. The purpose of this study was to test the effectiveness of a functional appliance specially designed for sheep and to evaluate the sheep as a model for dentofacial orthopaedic research. Eight, 4-month-old, castrated male Merino sheep were randomly assigned to experimental or control groups, with four in each group. Cast functional appliances were fabricated for the animals in the experimental group. The treatment period was 15 weeks. Dental casts, endosseous implant markers and cephalograms were used to analyse the displacement of the mandible. Undemineralised sagittal sections of TMJ were used to evaluate the tissue responses induced by the appliances. The weight of the animals was measured monthly to monitor their growth. The growth of the metacarpus was also measured. During the experimental period, the animals maintained their weight within the normal range and grew normally. The appliance displaced the mandible to a downward and forward position. The adaptive responses in the TMJ induced by the appliances included changed anteroposterior shape of the condylar process, anteriorly thickened condylar cartilage, and a thickened compact bone layer along the anterior surface of the posterior wall of the glenoid fossa. The sheep coped well with the experimental procedures and the appliance used was demonstrably effective in inducing adaptive responses in the TMJ. Consequently, it is believed that the sheep is an appropriate animal model to study growth modifications in the TMJ region.

Adaptation, Physiological↗
PubMed2002

A histomorphometric study of adaptive responses of cancellous bone in different regions in the sheep mandibular condyle following experimental forward mandibular displacement.

Forward mandibular displacement in animal models is associated with faster and/or redirected condylar growth. Here the effect of forward displacement induced with an intraoral appliance on modelling/remodelling of the mandibular condyle was investigated in eight, 4-month-old, castrated male Merino sheep, randomly allocated to experimental and control groups (n=4 in each group). The study period was 15 weeks, during that time, (1). calcein, (2). tetracycline, and (3). alizarin red S fluorochromes were given to all animals from day 1. Midsagittal sections of the temporomandibular joints were selected for analysis. Dynamic variables of bone formation, static indices of bone-forming and -resorbing activity, and structural indices of trabecular bone were estimated histomorphometrically. The sampling site was divided into two regions for analysis: (a). a 'subchondral region' (2 and 3 labels only), believed to be the bone newly formed during the experimental period; (b). a 'central region' (labelled by all three fluorochromes), believed to be the bone that existed before the experiment. Regional differences in adaptive response were found. In the experimental group, the bone-volume fraction (BV/TV) of the subchondral regions had decreased, although the specific bone-surface and bone-formation rates had increased. This low BV/TV was associated with decreased trabecular thickness and increased trabecular separation. In the central condylar region of the experimental group, BV/TV was unchanged, but an increased osteoid surface was apparent when the eroded surface was taken into consideration. These adaptive condylar responses to forward mandibular displacement appeared to be the result of increased osteoblastic activity. Further studies are recommended to examine why the subchondral and central regions responded differently.

Adaptation, Physiological↗
PubMed2002

Eradication of the tropical bont tick in the Caribbean: is the Caribbean amblyomma program in a crisis?

The progress and problems in the Caribbean Amblyomma Program (CAP) are reviewed since its inception in 1995. During 1998, there were funding and administrative management problems. USDA resolved the acute funding crisis, and after three years of negotiation, the CAP has now secured an additional euro 1.5 million from the European Community. Changes in administration in 1998 included the withdrawal of IICA from the program, and the transition during the decentralization of administrative and financial management from FAO headquarters to the Regional Office for Latin America and the Caribbean, based in Chile. A general overview of technical progress and one case study, St. Kitts, is presented. One major concern that emerged during 2000 is that the elimination of the small remaining tropical bont tick (TBT) "hot spots" in both St. Kitts and St. Lucia remained elusive. Why is this so? Egrets? Alternative residual hosts? Or is it fatigue in both technical and administrative management functions? Of even greater concern is the finding of two, apparently new, foci in St. Croix (USVI) in the north and St. Vincent in the south. A critical overview of the program has identified one major remaining constraint-an appropriate management support function at both regional and, in some countries, at the national level. A proposal for a revised management strategy, coupled with the identification of a future strategy to succeed the CAP, namely a Caribbean Animal Resources Management (CARM) Program.

Animals↗
PubMedDate not supplied

Pain management for newborn circumcision.

PURPOSE: To describe current newborn circumcision pain interventions and to identify which forms of analgesia were most effective. METHOD: Each male newborn was assessed for pain during the circumcision procedure and at 15-minute intervals after the procedure using the FLACC pain scale. The type and combination of analgesia was also recorded on the pain assessment record. RESULTS: Pain scores were highest for newborns receiving no analgesia during circumcision. Newborns circumcised with the dorsal block and the ring block in combination with the concentrated oral sucrose had the lowest pain scores. The sucrose alone did not provide sufficient analgesia; however, it did reduce the FLACC score somewhat when used in conjunction with other analgesics/anesthesia. CONCLUSIONS: Information obtained from this project facilitated a change in policy wherein newborn circumcision is performed only with the use of analgesia and not concentrated oral sucrose alone.

Administration, Oral↗
PubMedDate not supplied

Liquid chromatographic analysis of aflatoxin using post-column photochemical derivatization: collaborative study.

Aflatoxin analysis, with post-column derivatization using a photochemical reactor for enhanced detection (PHRED) system for derivatization, has been compared to the officially recognized iodine and Kobra cell derivatization systems. This photochemical system has been extensively used for screening peanuts by some U.S. Department of Agriculture laboratories for many years. From their periodic method checks, using standard spiked samples, an 80 sample series with each of the 3 derivatization methods was statistically analyzed. Paired comparisons, using the same sample extract, were also made between the PHRED and one of the other 2 methods, among laboratories in 4 different countries, on a variety of naturally contaminated commodity products. The differences between the techniques were not significant for peanuts, but for corn the photochemical system consistently gave slightly higher values for aflatoxins B1 and B2 than the Kobra cell method. However, a comparison of all sample results showed no significant differences between methods. The Pearson correlation coefficients for aflatoxin B1 in 102 test samples and aflatoxin B2 in 94 test samples were 0.9994 and 0.9874, respectively. The probability factor was P < 0.0001, and the t-tests were not significantly different except for the corn. These indicated that the PHRED system is equivalent to the iodine and Kobra cell methods for peanuts relative to the current official procedures, but the PHRED system has a slightly high bias for corn compared to the iodine and Kobra cell systems.

Aflatoxin B1↗
PubMedDate not supplied

Implementing evidence-based nursing practice in a pediatric hospital.

A commonly stated reason for dissatisfaction among nurses is that their input regarding patient care and suggestions for improvement in the workplace environment are not solicited or recognized. Nurses can have an active voice in their practice by using the five steps for implementing EBP and being involved in the process of EBP within the work setting. Pediatric nurses have the unique opportunity to become empowered and make a significant difference in their patients' and family's lives by continually asking questions about treatments and care, searching for and evaluating the evidence to support or refute traditional practices, implementing best practice, and evaluating the effectiveness of the evidence as it applies to nursing practice.

Child↗