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Biomedical subjects

M Foster

Publications and source records attributed to M Foster.

At least 19 recordsLinked to original sources
PubMed2006

Unexpected higher-order effects in charged particle impact ionization at high energies.

Most of the experimental and theoretical studies of electron-impact ionization of atoms, referred to as (e, 2e), have concentrated on the scattering plane. The assumption has been that all the important physical effects will be observable in the scattering plane. However, very recently it has been shown that, for C6+-helium ionization, experiment and theory are in nice agreement in the scattering plane and in very bad agreement out of the scattering plane. This lack of agreement between experiment and theory has been explained in terms of higher-order scattering effects between the projectile and target ion. We have examined electron-impact ionization of magnesium and have observed similar higher-order effects. The results of the electron-impact ionization of magnesium indicate the possible deficiencies in the calculation of fully differential cross sections in previous heavy particle ionization work.

Journal Article↗
PubMed2006

Young-type interference in (e, 2e) ionization of H(2).

We have investigated the electron impact single ionization of the hydrogen molecule, with fully determined kinematics. The experimental and theoretical results are compared with He ionization under the same conditions. The results indicate that the ejected electron angular distribution for H(2) is modified due to Young-type interference between ionization amplitudes for scattering from the two centers in the hydrogen molecule. The observable result is a suppression of the backward scattering (recoil) peak compared with the binary peak.

Journal Article↗
PubMed2006

In vitro infectability of prosthetic mesh by methicillin-resistant Staphylococcus aureus.

Although mesh use is important for effective herniorrhaphy in adults, prosthetic infections can cause serious morbidity. Bacterial adherence to the mesh is a known precursor to prosthetic infection. We compared the ability of common mesh prosthetics to resist bacterial adherence. The meshes studied included polypropylene (Marlex, expanded polytetrafluoroethylene (PTFE) with and without silver chlorhexidine coating (DualMesh Plus and Dualmesh) composite meshes (Composix E/X, Proceed, and Parietex Composite) and lightweight polypropylene meshes (TiMesh, Ultrapro, and Vypro). Fifteen samples of each mesh type were individually inoculated with a suspension of 10(8 )methicillin-resistant Staphylococcus aureus (MRSA) in tryptic soy broth. After incubation at 37 degrees C for 1 h, the mesh pieces were then removed and serially washed. The colony-forming units (CFU) of MRSA present in the initial inoculum, at the end of the 1-h warm-water bath (broth count), and the pooled washes (wash count), were determined using serial dilutions and spot plating. The bacteria not accounted for in the broth or wash counts were considered adhered to the mesh. Samples of each mesh type were also analyzed using scanning electron microscopy (SEM). Data are presented as the mean percentage adherence with ANOVA and Tukey's test used to determine significance (P<0.05). The DualMesh Plus mesh had no detectable MRSA in the broth or the pooled wash samples. Dualmesh had less adherence compared with Marlex, Proceed, and Vypro (P<0.05). Conversely, Vypro had a statistically higher adherence (96%, P<0.05) as compared to TiMesh, Ultrapro, Composix E/X, and Parietex Composite. SEM confirmed bacterial adherence to all the mesh types except DualMesh Plus. The ability of a biomaterial to resist infection has an important clinical significance. DualMesh Plus, due to its antimicrobial coating, is the only mesh type of the nine tested that demonstrated a bactericidal property. Standard PTFE (Dualmesh) also had less bacterial adherence. Vypro demonstrated an increase in bacterial adherence; this was possibly due to the multifilament polyglactin 910 weaved within the prolene component of the mesh.

Bacterial Adhesion↗
PubMed2006

The impact of an ICU liaison nurse on discharge delay in patients after prolonged ICU stay.

The mismatch between intensive care unit (ICU) bed availability and demand may be improved with timely patient discharges, however little is known about the nature and contributing factors of discharge delays. This study investigated the impact of a specific intervention--the ICU liaison nurse role--in reducing ICU discharge delay using a prospective block intervention study. One hundred and eighty-six ICUpatients (101 control and 85 liaison nurse intervention) with an ICU length of stay of three days or longer and who survived to ICU discharge were examined. The liaison nurse was involved in assessment of patients for transfer to the ward, with a major focus on coordinating patient transfer including liaison with ward staff prior to and following ICU discharge. Logistic regression was used to quantify the risk of discharge delay associated with the liaison nurse intervention with adjustment for potential confounding variables. While no demographic or clinical variables were significant predictors of ICU discharge delay, those in the liaison nurse group were almost three times less likely to experience a discharge delay of at least two hours and about 2.5 times less likely to experience a delay of four or more hours. The positive effect of the liaison nurse role in reducing the discharge delay remained after adjustingforpotential confounders. We conclude that the liaison nurse role is effective in reducing the discharge delay in ICU transfer

Adult↗
PubMed2005

Chondrocyte calcium-sensing receptor expression is up-regulated in early guinea pig knee osteoarthritis and modulates PTHrP, MMP-13, and TIMP-3 expression.

OBJECTIVE: Growth plate chondrocytes up-regulate calcium-sensing receptor (CaR) expression as they mature to hypertrophy. In cells other than chondrocytes, extracellular calcium-sensing via the CaR functions partly to promote expression of parathyroid hormone-related protein (PTHrP), a critical regulator of endochondral development. Moreover, PTHrP is up-regulated in human osteoarthritis (OA) and surgically induced rabbit OA cartilages and may promote both chondrocyte proliferation and osteophyte formation therein. Hence, we examined chondrocyte CaR-mediated calcium-sensing in OA pathogenesis. METHODS: We studied spontaneous knee OA in male Hartley guinea pigs. We also evaluated cultured bovine knee chondrocytes and immortalized human articular chondrocytes (CH-8 cells), employing the CaR calcimimetic agonist NPS R-467 or altering physiologic extracellular calcium (1.8 mM). RESULTS: Immunohistochemistry revealed that CaR expression became up-regulated in the superficial zone at 4 months of age in the guinea pig medial tibial plateau cartilage as early OA developed. CaR expression later became up-regulated in the middle zone. PTHrP content, measured by immunoassay, was significantly increased in the medial tibial plateau cartilage as OA developed and progressed. In cultured chondrocytic cells, CaR-mediated extracellular calcium-sensing, stimulated by the calcimimetic NPS R-467, induced PTHrP and matrix metalloproteinase (MMP)-13 expression and suppressed expression of tissue inhibitor of metalloproteinase (TIMP)-3 dose-dependently, effects shared by elevated extracellular calcium (3 mM). Extracellular calcium-sensing appeared essential for PTHrP and interleukin (IL)-1 to induce MMP-13 and for PTHrP 1-34 to suppress TIMP-3 expression. CONCLUSIONS: Chondrocyte CaR expression becomes up-regulated early in the course of spontaneous guinea pig knee OA. Chondrocyte CaR-mediated extracellular calcium-sensing promotes PTHrP expression, modulates the effects of PTHrP and IL-1, and promotes MMP-13 expression and TIMP-3 depletion. Our results implicate up-regulated extracellular calcium-sensing via the CaR as a novel mediator of OA progression.

Animals↗
PubMed2004

The susceptibility of prosthetic biomaterials to infection.

BACKGROUND: Despite the use of a sterile technique and the administration of prophylactic antibiotics during surgical procedures, mesh infection continues to complicate the use of biomaterials. The purpose of this study was to compare the susceptibility to infection of prosthetic biomaterials in a live-animal model. METHODS: The following seven prosthetic mesh biomaterials were used in this study. Expanded polytetrafluoroethylene (ePTFE) with silver/chlorhexidine (DM+), ePTFE (DM), porcine intestinal submucosa (S), polypropylene (M), ePTFE/polypropylene (X), hyaluronate/carboxymethylcellulose/polypropylene (SM), and human acellular dermal matrix (A). Lewis rats (n = 108) underwent creation of a single ventral hernia; 105 of them were repaired with a different mesh (2-cm2 piece). Twelve pieces of each mesh were inoculated at the time of hernia repair with 10(8) Staphylococcus aureus (n = 84). Three pieces of each mesh were placed without bacterial inoculation (n = 21). In three animals, no mesh was placed; instead, the peritoneum of the hernia defect was inoculated (n = 3). After 5 days, the animals were killed and the mesh was explanted (peritoneum for the nonmesh control). The mesh was vortex-washed and incubated in tryptic soy broth. Bacterial counts were determined using serial dilutions and spot plates and quantified in colony-forming units (CFU) per square centimeter of mesh present in the vortex wash fluid (wash count) and the soy broth (broth count). Data are presented as the mean log(10), with analysis of variance (ANOVA) and Tukey's test used to determine significance (p < 0.05). RESULTS: The DM+ material had no detectable live bacteria in the wash or broth counts in 10 of 12 tested samples (p = 0.05). Of the samples that showed bacterial growth, the peritoneum control group had a lower wash count than A (p = 0.05) and the lowest broth count of all the materials except for DM+ (p = 0.05). In addition, SM had a significantly lower wash count than A (p = 0.05), with no broth count difference. In regard to wash and broth counts, DM, M, X, SM, S, and A were no different (p = NS). CONCLUSIONS: The DM+ material was the least susceptible to infection. Impregnation with silver/chlorhexidine killed the inoculated bacteria, preventing their proliferation on the mesh surface. Other than DM+, native peritoneal tissue appears to be the least susceptible to infection. Silver/chlorhexidine appears to be an effective bactericidal agent for use with mesh biomaterials.

Animals↗
PubMed2004

Cancellous bone changes in the radius of patients with rheumatoid arthritis: a cross-sectional quantitative macroradiographic study.

OBJECTIVE: Fractal signature analysis (FSA), a computerized method of textural analysis, permits the separate measurement of changes in vertical and horizontal trabeculae based on the fractal dimension over a range of trabecular widths (fractal signature). We determined whether the FSA of high-definition macroradiographs (x5 magnification) quantified radiographic changes at sites of osteopenia and erosion formation in the rheumatoid arthritis (RA) hand. METHODS: Sixty-seven RA patients had macroradiographs of the left wrist and hand. The distal radius was scored and grouped from very mild (RA1) to moderate (RA4) disease. Macroradiographs were digitized and FSA of horizontal and vertical trabecular organization was performed in the radius at sites of periarticular osteopenia, erosion formation and at a mid-metaphyseal site. The RA groups were compared with 11 healthy non-arthritic subjects using ANOVA and Dunnett's tests. RESULTS: Compared to the non-arthritic hands, FSA at the distal radius in groups RA1 to RA4 measured significantly lower (P<0.05) fractal signatures. The fractal signatures were lowest in RA4 involving small, medium to large sized vertical trabeculae at the periarticular osteopenic (0.18 to 0.84 mm, P<0.01) and mid-metaphyseal sites (0.12 to 0.60 and 0.84 to 1.02 mm, P </= 0.04), and small to medium sized vertical trabeculae at the periarticular erosion site (0.24 to 0.84 mm, P<0.01). CONCLUSION: FSA quantified radiographic bone loss in the distal radius of RA patients with increasing radiographic severity in terms of lower fractal signatures compared with the non-arthritics. Disease-related bone loss was demonstrated by FSA to involve mainly vertical trabeculae at the periarticular osteopenic, periarticular erosion and the mid-metaphyseal sites indicating directionality of bone resorption in RA.

Arthritis, Rheumatoid↗
PubMed2003

Probing scattering wave functions close to the nucleus.

Recently, three-dimensional imaging of the ejected electrons following 100 MeV/amu C6+ single ionization of helium led to the observation of a new structure not predicted by theory [Nature (London) 422, 48 (2003)]]. Instead of the usual "recoil lobe" centered on the momentum-transfer axis, a ring-shaped structure centered on the beam axis was observed. New measurements at 2 MeV/amu exhibit a similar structure, which is now predicted by theory. We argue that the same theory failed at 100 MeV/amu because the faster projectiles probe distances much closer to the nucleus, where our multiple-scattering model is expected to break down.

Journal Article↗
PubMed2003

Classifying client goals in community-based ABI rehabilitation: a taxonomy for profiling service delivery and conceptualizing outcomes.

PURPOSE: To develop, confirm and trial a framework for analysing the content of goals set within community-based rehabilitation. This framework (taxonomy) is proposed as a tool to assist in service evaluation and outcome exploration. METHOD: Qualitative thematic analysis and categorization of 1765 rehabilitation goal statements in a four phase process of synthesis, refinement, verification and application. RESULTS: A taxonomy of goal content was developed comprising 21 categories within five domains, utilizing 125 descriptors. The taxonomy demonstrated good inter-rater consistency and was able to discriminate between similar but related data sets comprising goal statements. CONCLUSION: Structured analysis of the content of goal setting (particularly in community rehabilitation) utilizing a framework such as the proposed taxonomy has considerable potential as a 'window' into service delivery to broaden the parameters of existing service evaluation and to more clearly link outcome exploration to intervention.

Activities of Daily Living↗
PubMed2001

Effects of cyclosporin A administered into the airways against antigen-induced airway inflammation and hyperreactivity in the rat.

The immunosuppressant cyclosporin A given orally has anti-asthma properties but carries an undesirable risk of systemic effects. We administered cyclosporin A to Brown Norway rats either orally (p.o.) or topically by intratracheal (i.t.) instillation into the airways before inhaled antigen. Cyclosporin A suppressed the antigen-induced accumulation of activated (CD25+) CD4+ T lymphocytes and eosinophils in the lung, interleukin-5 mRNA expression in lung tissue and airway hyperreactivity. Intratracheal cyclosporin A suppressed cell accumulation at a 10-fold lower dose than that required orally. Minimum effective doses were 3 mg x kg(-1) i.t. and 30 mg x kg(-1) p.o. Intratracheal administration reduced the plasma concentration and systemic exposure compared with an equieffective oral dose, but the reduction (4-5-fold) was not as large as anticipated. Our data suggests that although topical administration to asthmatics would provide some potential for an improved safety margin, it may not offer any major advantage over existing oral therapy. However, the data clearly demonstrate that a novel immunosuppressant with similar anti-inflammatory properties but reduced potential for systemic effects would offer an attractive therapy for severe asthma.

Administration, Inhalation↗
PubMed2001

Diagnostic procedures for the urogenital system.

In making clinical decisions concerning the urogenital system, the emergency department physician has many different diagnostic tools at his or her disposal. Choosing the appropriate diagnostic study can often be difficult. For well over a thousand years, the initial step in assessing almost any urologic condition has been to examine the urine. Thankfully, this has progressed from a gustatory approach to the modern urinalysis. There is certainly a great deal of information that may be gleaned from the urinalysis, but the physician must also be mindful of its limitations. Overuse of the urinalysis can result in unwanted and unhelpful information. Although IVP is still the study of choice in assessing the functional status of the kidney, the introduction of CT and ultrasound technology to clinical medicine has revolutionized the emergency department assessment of the urogenital tract. CT and ultrasound can help differentiate between the urologic emergencies and the various surgical conditions that can mimic them.

Diagnostic Imaging↗
PubMed2001

The discovery of RPR 200765A, a p38 MAP kinase inhibitor displaying a good oral anti-arthritic efficacy.

RPR132331, a 2-(2-dioxanyl)imidazole, was identified as an inhibitor of tumour necrosis factor (TNF)alpha release from lipopolysaccharide (LPS)-stimulated human monocytes. An intensive programme of work exploring the biology, toxicity and physical chemistry of a novel series of inhibitors, derived from RPR132331, has led to the identification of RPR200765A, a development candidate for the treatment of rheumatoid arthritis (RA). RPR200765A is a potent and selective inhibitor of p38 MAP kinase (IC50 = 50 nM). It inhibits LPS-stimulated TNFalpha release both in vitro, from human monocytes (EC50 = 110 nM), and in vivo in Balb/c mice (ED50 = 6 mg/kg). At oral doses between 10 and 30 mg/kg/day it reduces the incidence and progression in the rat streptococcal cell wall (SCW) arthritis model when administered in either prophylactic or therapeutic dosing regimens. The compound, which is a mesylate salt and exists as a stable monohydrate, shows good oral bioavailabiltiy (F = 50% in the rat) and excellent chemical stability. The data from the SCW disease model suggests that RPR200765A could exhibit a profile of disease modifying activity in rheumatoid arthritis (RA) patients which is not observed with current drug therapies.

Administration, Oral↗
PubMed2001

Caregivers of ICU patients discharged home: what burden do they face?

Reforms in healthcare aimed at cost-cutting have led to early hospital discharge for many patients, including those who have sustained critical illness or injury requiring admission to an intensive care unit (ICU). Many former ICU patients experience ongoing health-related problems following discharge from hospital, and need ongoing support and care from their family once discharged. However, family members who take on a caregiving role often experience an enormous burden. The literature has demonstrated the impact of economic, social, physical and psychological factors on those who care for the critically ill following discharge. It is therefore essential that all nurses involved in the ongoing management of ICU patients have an understanding of the caregiving role, and consider both the patient and his/her carer in the discharge planning process. This paper reviews the literature on caregiving, and examines research studies which describe and measure the factors involved in the caregiving role. Although only a small number of studies specifically focus on caregivers of former ICU patients, findings suggest that these caregivers experience a substantial burden which is associated with the complexity of the patient's physical and psychological impairment, and complex technology. To enable nurses to incorporate planning strategies and interventions aimed at minimizing the impact on the caregiver, further research is needed to more fully explore, examine and measure the factors involved in caring for ICU patients post-discharge. Furthermore, ongoing research and evaluation of interventions will build an evidence-base to inform future practice.

Caregivers↗
PubMed2001

Increasing mouthguards usage among junior rugby and basketball players.

OBJECTIVE: To evaluate a Western Australian mouthguard promotion campaign, launched at the start of the 1997/98 junior rugby union and junior basketball seasons, aimed at increasing mouthguard usage at competition and training. METHOD: A quasi-experimental field design was used to assess the impact of the mouthguard campaign on behavioural change. Observational data were collected pre- and post-campaign on mouthguard usage by players present at a rugby and basketball competition event and at a training session. Junior Australian Rules Football players were used as a control group. RESULTS: Pre-post observational surveys showed a significantly greater increase in mouthguard usage in competition games among rugby union (77% to 84%) and basketball players (23% to 43%) compared with the control group (72% to 73%). All codes showed a post-campaign increase in mouthguard usage at training, but the intervention codes' increases were greater than the control's increase (rugby union: 29% to 40%; basketball: 11% to 36%; football: 34% to 40%). CONCLUSIONS: The campaign had a significant and substantial effect on behaviour and provides evidence of the benefits of leveraging a sponsorship to modify the behaviour of the target group. IMPLICATIONS: This campaign provides a model for promoting mouthguard usage in other sports among junior players.

Adolescent↗
PubMed2000

Immune alterations in three mouse strains following 2-deoxy-D-glucose administration.

Using 2-deoxy-D-glucose (2-DG)-induced stress, our laboratory has developed studies to define stress effects on immune responses. Here, we report effects of increasing doses of 2-DG on the immune response of BALB/c, C57BL/6 and BDF(1) mice 2 h after three injections of 0 to 2000 mg/kg of 2-DG. Female 4- to 5-week-old mice were euthanized and blood and spleens were collected. A suspension of partially purified mature T splenocytes was obtained by negative selection using J11.d2 antibodies. Glucose and corticosterone levels were measured in the plasma of each mouse. Splenocyte and mature T splenocyte suspensions were tested in in vitro proliferation assays with or without concanavalin A. Splenocytes were analyzed for the following cell-surface markers: CD3, TCR alpha/beta, CD4, CD8 and major histocompatibility complex (MHC) Class II. Significant increases in blood glucose levels were observed in C57BL/6 and BALB/c strains with the highest 2-DG dose (p<0.05). Corticosterone levels were higher in BDF(1) mice and C57BL/6 mice following the administration of 1000 and 2000 mg/kg of 2-DG, respectively (p<0.01). In vitro proliferation of mature T splenocytes in the presence of concanavalin A was decreased in BDF(1) (p<0.05) but not in BALB/c and C57BL/6 mice. In addition, in BDF(1) mice the decrease was highly correlated with an increase of CD3+ and TCR alpha/beta+ cells in the spleen. These results demonstrated high variability in the response of different mouse strains to 2-DG-induced stress.

Animals↗