PubMed Health⌕ Search

Biomedical subjects

M Peterson

Publications and source records attributed to M Peterson.

At least 19 recordsLinked to original sources
PubMed2007

Should the precautionary principle guide our actions or our beliefs?

Two interpretations of the precautionary principle are considered. According to the normative (action-guiding) interpretation, the precautionary principle should be characterised in terms of what it urges doctors and other decision makers to do. According to the epistemic (belief-guiding) interpretation, the precautionary principle should be characterised in terms of what it urges us to believe. This paper recommends against the use of the precautionary principle as a decision rule in medical decision making, based on an impossibility theorem presented in Peterson (2005). However, the main point of the paper is an argument to the effect that decision theoretical problems associated with the precautionary principle can be overcome by paying greater attention to its epistemic dimension. Three epistemic principles inherent in a precautionary approach to medical risk analysis are characterised and defended.

Culture↗
PubMed2006

Elevated high-sensitivity C-reactive protein levels are associated with local inflammatory findings in patients with osteoarthritis.

OBJECTIVE: C-reactive protein (CRP) has been associated with disease progression in patients with osteoarthritis (OA), but the reasons for this remain unclear. We hypothesized that higher CRP would be related to local inflammatory findings in the joints of patients with OA. METHODS: Plasma and synovial membrane specimens from 54 OA patients undergoing total hip or knee arthroplasty or arthroscopy were obtained. Synovial fluid was obtained from 25 of these patients. Hematoxylin and eosin stained synovial membrane sections were scored for degree of inflammatory cell infiltration. Plasma high-sensitivity CRP (hsCRP) levels, and serum and synovial fluid interleukin (IL)-6 and IL-1beta levels were measured by enzyme-linked immunosorbent assay. RESULTS: Fifty-seven percent of patients with idiopathic OA had inflammatory infiltrates within the synovial membrane. The mean hsCRP level in patients with inflammatory infiltrates was significantly higher than those without inflammation (4.7 +/- 5.0 mg/L vs 1.7 +/- 3.6 mg/L, P = 0.003). There were significant correlations between hsCRP levels and synovial fluid IL-6 (r = 0.64, P = 0.0006), degree of synovial inflammatory infiltration (r = 0.43, P = 0.002), and body mass index (r = 0.31, P = 0.02). Multivariate analysis indicated that only degree of inflammatory infiltrate was significantly associated with hsCRP level (P = 0.026). CONCLUSION: These results suggest that systemic hsCRP levels reflect synovial inflammation in OA patients, perhaps by means of synovial IL-6 production. Future studies are needed to clarify how these infiltrates and their products may contribute to disease pathogenesis.

Adult↗
PubMed2006

mTOR inhibition induces endothelial progenitor cell death.

Immunosuppressants are necessary to prevent graft rejection after solid organ transplantation. However, they are also known to have significant side effects, including endothelial toxicity. Endothelial progenitor cells originate in the bone marrow and are recognized by their angiogenic and endothelial reparative properties. The effects of the immunosuppressants cyclosporine A (CyA), tacrolimus and rapamycin were analyzed on endothelial progenitor-like cells. Rapamycin induced rapid cell death, even at concentrations much lower than those used clinically, in peripheral blood mononuclear cells (PBMC) cultured to favor outgrowth of endothelial progenitors. Cyclosporine A and tacrolimus had no significant effects at clinical concentrations. The effect of rapamycin was specific to endothelial progenitor cells, in particular to the early stages of differentiation, as a lesser effect was observed in late outgrowth endothelial progenitors, mature aortic endothelial cells, and macrophages derived from the same PBMCs. The mechanism of cell death appeared to be apoptosis; however, its induction was probably multifactorial and did not depend on caspase or cathepsin activation. In conclusion, rapamycin induces endothelial progenitor cell death, possibly because it blocks survival signals given by growth factors critically required by these cells.

Apoptosis↗
PubMed2005

Combined research and clinical learning make Rural Summer Studentship Program a successful model.

CONTEXT: Many medical schools would like to provide students with opportunities to learn and perform practical research and to have positive rural learning experiences. Rural physicians often have research ideas, but may lack the skills or assistance to perform the research. PROGRAM DESCRIPTION: The unique Rural Summer Studentship Program (RSSP) at The University of Western Ontario (Western) places students with preceptors in small and mid-sized communities throughout Southwestern Ontario where they have an opportunity to perform rural health research, combined with clinical learning, for 8 weeks in the summer after the first or second year of medical school. Secretarial coordination, research assistant support and senior faculty supervision were provided. OUTCOMES: From 1999-2003 inclusive, 44 students have participated including eight who participated over two summers. Projects were carried out in more than 20 communities with over 30 preceptors. Already, two students have had their research published in peer-reviewed journals and six have presented at major conferences. Participating students indicated an increase in interest in rural and regional medicine and in their knowledge of rural and regional medicine and patient care. They rated the value of RSSP highly as part of their medical education, even compared with other electives/selectives. CONCLUSION: The RSSP model developed at Western provides a highly rated, successful combination of supported medical student research and clinical learning with preceptors in small and mid-sized communities.

Education, Medical, Undergraduate↗
PubMed2005

Factors associated with development of stroke long-term after myocardial infarction: experiences from the LoWASA trial.

OBJECTIVE: To describe factors associated with the development of stroke during long-term follow-up after acute myocardial infarction (AMI) in the LoWASA trial. PATIENTS: Patients who had been hospitalized for AMI were randomized within 42 days to receive either warfarin 1.25 mg plus aspirin 75 mg daily or aspirin 75 mg alone. DESIGN: The study was performed according to the probe design, that is open treatment and blinded end-point evaluation. SETTING: The study was performed in 31 hospitals in Sweden. The mean follow-up time was 5.0 years with a range of 1.7-6.7 years. RESULTS: In all, 3300 patients were randomized in the trial, of which 194 (5.9%) developed stroke (4.2% nonhaemorrhagic, 0.5% haemorrhagic and 1.3% uncertain. The following factors appeared as independent predictors for an increased risk of stroke: age, hazard ratio and 95% confidence interval (1.07; 1.05-1.08), a history of diabetes mellitus (2.4; 1.8-3.4), a history of stroke (2.3; 1.5-3.5), a history of hypertension (2.0; 1.5-2.7) and a history of smoking (1.5;1.1-2.0). Most of these factors were also predictors of a nonhaemorrhagic stroke whereas no predictor of haemorrhagic stroke was found. CONCLUSION: Risk indicators for stroke long-term after AMI were increasing age, a history of either diabetes mellitus, stroke, hypertension or smoking.

Age Factors↗
PubMed2005

Relationship of quality of life and physical function measures with disease activity in children with systemic lupus erythematosus.

The objective of this study is to assess relationship of systemic lupus erythematosus (SLE) activity with quality of life (QOL) and physical function and determine which is more closely correlated with SLE activity in children; and identify factors critical to children's QOL. In this cross-sectional study, children with SLE and parents completed corresponding versions of physical function (Childhood Health Assessment Questionnaire CHAQ), and QOL (Pediatric Quality of Life Inventory-PedsQL Generic/Rheumatology modules) questionnaires. SLE Disease Activity Index (SLEDAI), Systemic Lupus International Collaborating Clinics/ACR Damage Index (SDI), severity, self-concept and socioeconomic status (SES) were measured. For 24 children, CHAQ scores significantly correlated with SLEDAI (rho = 0.4, p = 0.04), SDI (rho = 0.6, p = 0.004), and associated with severity (p = 0.03). PedsQL scores did not significantly correlate with above parameters. Higher self-concept/SES correlated (p < 0.05) with better physical function and QOL. For 19 parents, the only significant correlation was between SLEDAI and Worry domain-Rheumatology module (rho = 0.5, p = 0.01). Lack of strong correlation of disease activity with QOL and physical function suggests that they are different constructs with partial overlap, and should be considered collectively while evaluating the impact of SLE on children/families. Self-concept and SES should be assessed while measuring QOL in children. Larger sample is required to confirm results.

Adolescent↗
PubMed2003

Acupuncture for chronic low back pain in older patients: a randomized, controlled trial.

OBJECTIVE: To determine if acupuncture is an effective, safe adjunctive treatment to standard therapy for chronic low back pain (LBP) in older patients. METHODS: The inclusion criteria for subjects were: (i) LBP > or =12 weeks and (ii) age > or =60 yr; the exclusion criteria were (i) spinal tumour, infection or fracture and (ii) associated neurological symptoms. The subjects were randomized to two groups. The control group of subjects continued their usual care as directed by their physicians, i.e. NSAIDs, muscle relaxants, paracetamol and back exercises. Subjects in the acupuncture group in addition received biweekly acupuncture with electrical stimulation for 5 weeks. Outcome was measured by the modified Roland Disability Questionnaire (RDQ) at weeks 0, 2, 6 and 9. The primary outcome measure was change in RDQ score between weeks 0 and 6. RESULTS: Fifty-five patients were enrolled, with eight drop-outs. Twenty-four subjects were randomized to the acupuncture group and 23 were randomized to the control group. Acupuncture subjects had a significant decrease in RDQ score of 4.1 +/- 3.9 at week 6, compared with a mean decrease of 0.7 +/- 2.8 in the control group (P = 0.001). This effect was maintained for up to 4 weeks after treatment at week 9, with a decrease in RDQ of 3.5 +/- 4.4 from baseline, compared with 0.43 +/- 2.7 in the control group (P = 0.007). The mean global transition score was higher in the acupuncture group, 3.7 +/- 1.2, indicating greater improvement, compared with the score in the control group, 2.5 +/- 0.9 (P < 0.001). Fewer acupuncture subjects had medication-related side-effects compared with the control group. CONCLUSIONS: Acupuncture is an effective, safe adjunctive treatment for chronic LBP in older patients.

Acupuncture Analgesia↗
PubMed2001

Evidence for non-selective preservation of organic matter in sinking marine particles.

The sinking of particulate organic matter from ocean surface waters transports carbon to the ocean interior, where almost all is then recycled. The unrecycled fraction of this organic matter can become buried in ocean sediments, thus sequestering carbon and so influencing atmospheric carbon dioxide concentrations. The processes controlling the extensive biodegradation of sinking particles remain unclear, partly because of the difficulty in resolving the composition of the residual organic matter at depth with existing chromatographic techniques. Here, using solid-state 13C NMR spectroscopy, we characterize the chemical structure of organic carbon in both surface plankton and sinking particulate matter from the Pacific Ocean and the Arabian Sea. We found that minimal changes occur in bulk organic composition, despite extensive (>98%) biodegradation, and that amino-acid-like material predominates throughout the water column in both regions. The compositional similarity between phytoplankton biomass and the small remnant of organic matter reaching the ocean interior indicates that the formation of unusual biochemicals, either by chemical recombination or microbial biosynthesis, is not the main process controlling the preservation of particulate organic carbon within the water column at these two sites. We suggest instead that organic matter might be protected from degradation by the inorganic matrix of sinking particles.

Animals↗
PubMed2001

Intraoperative nerve stimulation predicts postoperative potency.

OBJECTIVES: Intraoperative nerve stimulation has been used to map the course of cavernosal nerve bundles to aid in nerve-sparing radical prostatectomy (RP). We sought to determine whether the intraoperative nerve stimulation response after removal of the prostate specimen predicts postoperative potency. METHODS: We prospectively evaluated 63 consecutive patients undergoing RP. Among these 63 patients, 41 patients had a bilateral nerve-sparing procedure, and 22 underwent bilateral wide resection of the neurovascular bundles. Potency was determined at 1 year by direct patient interview. RESULTS: Of the 22 patients with wide resection, 16 (73%) had no observed stimulated response, 4 (18%) had a measurable tumescence response, and 2 (9%) had detumescence. All 22 patients were impotent postoperatively. At a minimum follow-up of 1 year, of the 41 patients who underwent nerve-sparing RP, 27 (66%) had postoperative erections sufficient for penetration. Of the 30 men with an intraoperative stimulated tumescence response, 24 (80%) were potent; of the 6 with a detumescence response, 2 (33%) were potent; and of the 5 with no stimulated nerve response, 1 (20%) was potent. A tumescence response was significantly more predictive of postoperative potency than no intraoperative response (P = 0.017). CONCLUSIONS: An intraoperative tumescence response with stimulation of the neurovascular bundles after prostate specimen removal is more likely to correspond to successful postoperative sexual function after nerve-sparing RP than is no response.

Adenocarcinoma↗
PubMed2001

Finding the right decision tree's induction strategy for a hard real world problem.

Decision trees have been already successfully used in medicine, but as in traditional statistics, some hard real world problems can not be solved successfully using the traditional way of induction. In our experiments we tested various methods for building univariate decision trees in order to find the best induction strategy. On a hard real world problem of the Orthopaedic fracture data with 2637 cases, described by 23 attributes and a decision with three possible values, we built decision trees with four classical approaches, one hybrid approach where we combined neural networks and decision trees, and with an evolutionary approach. The results show that all approaches had problems with either accuracy, sensitivity, or decision tree size. The comparison shows that the best compromise in hard real world problem decision trees building is the evolutionary approach.

Algorithms↗
PubMed2001

Improvement of in-rumen digestibility of alfalfa forage by genetic manipulation of lignin O-methyltransferases.

Lignin inhibits forage digestibility by ruminant animals, and lignin levels and the proportion of dimethylated syringyl (S) lignin monomers increase with progressive maturity in stems of forage crops. We generated transgenic alfalfa (Medicago sativa L.) with reduced lignin content and altered lignin composition. Down-regulation of caffeic acid 3-O-methyltransferase (COMT) reduces lignin content, accompanied by near total loss of S lignin, whereas down-regulation of caffeoyl coenzyme A 3-O-methyltransferase (CCoAOMT) reduces lignin content without reduction in S lignin. These changes are not accompanied by altered ratios of cell wall polysaccharides. Analysis of rumen digestibility of alfalfa forage in fistulated steers revealed improved digestibility of forage from COMT down-regulated plants, but a greater improvement in digestibility following down-regulation of CCoAOMT. The results indicate that both lignin content and composition affect digestibility of alfalfa forage, and reveal a new strategy for forage quality improvement by genetic manipulation of CCoAOMT expression.

Animals↗
PubMed2001

Inhibition of natural killer cell activation signals by killer cell immunoglobulin-like receptors (CD158).

The killer cell immunoglobulin-like receptor (KIR) family includes receptors that bind to HLA class I molecules on target cells and inhibit natural killer (NK)-cell cytotoxicity, and receptors such as KIR3DL7 with no known ligand and function. Inhibitory KIR recruit the tyrosine phosphatase SHP-1 to block signals transduced by any one of a number of activation receptors. Inhibition of overall protein tyrosine phosphorylation by SHP-1 during binding of KIR to MHC class I on target cells is selective, suggesting that a limited number of substrates are dephosphorylated by SHP-1. We have chosen to study KIR inhibition as it occurs during binding of KIR to MHC class I on target cells, despite the technical limitations inherent to studies of processes regulated by cell contact. KIR binding to MHC class I on target cells inhibits tyrosine phosphorylation of the activation receptor 2B4 (CD244) and disrupts adhesion of NK cells to target cells. Inhibition of proximal events in NK activation may increase the availability of NK cells by liberating them from non-productive interactions with resistant target cells. As the receptors and the signaling pathways that induce NK cytotoxicity are not fully characterized, elucidation of the inhibitory mechanism employed by KIR may provide insight into NK activation.

Amino Acid Sequence↗
PubMed2001

A statistical approach to an outbreak of endophthalmitis following cataract surgery at a hospital in the West of Scotland.

The number of cases of endophthalmitis following cataract surgery caused considerable concern in a West of Scotland hospital throughout 1998 and early 1999. A multi-disciplinary team including infection control nurses, doctors, public health officials,epidemiologists and statisticians was set up to investigate the situation. This paper examines the statistical issues surrounding the investigation. A method based on the Poisson distribution showed that the number of cases was significantly higher than expected. Fisher's Exact Test and Logistic Regression were then applied to the data from two related case control studies. These analyses showed that a higher risk of endophthalmitis was associated with being female, having a vitrectomy or having a previous history of respiratory disease. Finally, a method was devised to enable staff to recognize more quickly when the number of cases of endophthalmitis was becoming higher than expected. The method should find application in other clinical situations where the probability of rare events is known.

Case-Control Studies↗
PubMed2001

Return to work after inguinal hernia repair.

BACKGROUND: There is much variation in the time when a patient returns to work after inguinal hernia repair. Most surgical research has focused on the type of operation performed, but other factors may be equally or more important. This study attempted to identify these factors. METHODS: We prospectively studied the return to work after inguinal hernia repair in a convenience sample of 235 patients who were operated on by one surgical group. Ninety-three of these subjects, who were working and had complete data, were included in this analysis. Data were gathered through personal interviews, written surveys, and medical record reviews. The main outcome measures were actual and expected return to work. RESULTS: Primary tissue repair was done in 94% of the patients. The mean age was 49 years; 90% were male. The expected return to work was 10 days; the actual mean return to work after operation was 12 days (median, 7 days; range, 2 to 60 days) and was unrelated to preoperative functional status. Bivariate analysis showed that age, educational level, income level, occupation, symptoms of depression, and the expected return to work accounted for 61% of the variation in actual return to work. CONCLUSIONS: Factors other than operative technique, including patient expectations, are strongly associated with return to work after inguinal hernia repair. Depression significantly delayed return to work. More research is needed to understand how expectations are formed and how decisions are made regarding return to work, and whether these can and/or should be influenced by surgeons, employers, or others to promote earlier return to work.

Analysis of Variance↗
PubMed2001

Variability of results of cavernous nerve stimulation during radical prostatectomy.

PURPOSE: We assess the reliability of intraoperative cavernous nerve stimulation for producing an erectile response during radical prostatectomy. MATERIALS AND METHODS: In 61 patients cavernous nerve function was assessed during radical retropubic prostatectomy using a CaverMap nerve stimulator. Control stimulation was also performed before and after prostatic dissection by placing the nerve stimulator tip on the anterior bladder wall. An increase in penile circumference measured by the device was considered a tumescence response while any measurable detumescence was also categorized. RESULTS: Patient age ranged 43 to 72 years (mean 59.8). Before apical dissection 41% and 46% had tumescence, 31% and 21% had detumescence, and 28% and 33% had no response with stimulation of the neurovascular bundle and anterior bladder wall, respectively. After dissection 42% and 25% had tumescence, 16% and 18% had detumescence, and 42% and 57% had no response with stimulation of the neurovascular bundle and anterior bladder wall, respectively. CONCLUSIONS: A response to neurovascular bundle stimulation using this device does not necessarily correlate with the precise anatomical location of the cavernous nerves. There is considerable background variability related to anesthesia, surgical manipulation and other undefined factors that may cause minor but measurable changes in penile circumference.

Adult↗
PubMed2001

Visual function and quality of life among patients with giant cell (temporal) arteritis.

OBJECTIVE: To investigate patient perception of visual and systemic disability associated with giant cell arteritis (GCA) and whether the perceived disability can be correlated with visual performance measures. METHODS: We prospectively evaluated and compared the visual performance and quality of life survey for 20 patients with GCA after 4 to 5 weeks of corticosteroid therapy and after one year of therapy. We measured visual acuity, contrast sensitivity, and threshold perimetry and patients completed the Activities of Daily Vision Scale (ADVS) and the short-form of the Health Survey (SF-36). The results were grouped by GCA affected or unaffected eye or by better or worse eye and reported as a decimal and percent impairment for acuity, log units for contrast, mean deviation and the Advanced Glaucoma Intervention Study (AGIS) score for perimetry. The results for patients with and without visual loss were compared. Correlation analyses between ADVS categories and visual performance measures, SF-36 categories and the presence of visual loss, total corticosteroid dose, systemic symptoms, secondary hypertension or diabetes mellitus, the presence of vertebral fracture, and visual performance were performed. RESULTS: Day driving was the only ADVS category significantly reduced at baseline in patients with visual loss (62.5) compared with those without visual loss (96.3, P = 0.04). Modest to moderate correlations between ADVS categories were most frequent for percent binocular acuity impairment with day driving (r = -0.62, P = 0.017), with distance vision (r = -0.5, P = 0.02), and with glare (r = -0.59, P = 0.006); and the AGIS score of the worse eye with day driving (r = -0.66, P = 0.01), with near vision (r = -0.49, P = 0.03), and with glare (r = -0.48, P = 0.04). The baseline SF-36 scores did not correlate with the presence of vision loss at baseline or systemic complications. The ADVS and SF-36 scores were similar at one year. The total dose of corticosteroids only had a modest correlation with the one-year mental health score (r = -0.45, P = 0.05), but there was no correlation between SF-36 scores and other systemic side effects of steroid therapy. CONCLUSION: Except for the day driving score, the ADVS did not differ between patients with and without visual loss. The SF-36 did not distinguish between patients with and without visual loss and did not reveal significant trends. The ADVS and SF-36 did not reveal significant disability in GCA patients and there were no strong correlations with any visual performance or systemic measures.

Activities of Daily Living↗
PubMed2001

Mental health issues in the workplace: a case for a new managerial approach.

Anger, stress, and depression in the workplace are growing concerns among management. Traditionally, health outcomes have functioned under the realm of workplace health professionals. This study assessed whether a traditional worksite health promotion program had an impact on mental health factors. The results suggested that worksite health promotion programs play a limited role in ameliorating work-related mental health outcomes. Rather, management must play a greater role in addressing workplace stress, anger, and depression.

Anger↗