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S Richardson

Publications and source records attributed to S Richardson.

At least 109 records · Page 6Linked to original sources
PubMed1994

Evidence that verotoxins (Shiga-like toxins) from Escherichia coli bind to P blood group antigens of human erythrocytes in vitro.

The interaction of verotoxins (VTs) with human erythrocytes (RBCs) in vitro was investigated, with particular reference to the role of P blood group glycolipids that are structurally related to the known VT receptors. RBC binding of purified VT1, VT2, VT2c, and VT2e was detected by direct and indirect immunofluorescence. Glycolipids were extracted from defined RBCs, separated by thin-layer chromatography, and assessed for VT binding in an overlay assay by adding toxin and specific antibodies. All VTs bound to P1 phenotype (Pk, P, and P1 antigens) and P2 phenotype (Pk and P antigens) RBCs but not to p phenotype (lacking the Pk, P, and P1 antigens) RBCs. Binding of VT1 and VT2 was approximately 10-fold greater to P1 and the rare Pk2 (Pk antigen but no P1 or P antigen) phenotype cells than to P2 phenotype RBCs, whereas VT2e bound equally well to P1 and P2 phenotype cells. The VT1 and VT2 immunofluorescence results correlated with the detection of P1 and/or increased amounts of Pk (globotriaosylceramide) antigen; VT2e immunofluorescence correlated with the detection of P (globotetraosylceramide) antigen. The Pk band pattern and VT binding observed in the thin-layer chromatogram of human P1 and P phenotype RBC extracts varied from that of human kidney and Pk1 phenotype (Pk and P1 antigens) RBCs. We conclude that each VT binds to human RBCs in vitro by utilizing specific P blood group glycolipids as receptors. On P1 and P phenotype RBCs, the accessibility of the Pk antigen for VTs appeared to be restricted. The occurrence of VT-RBC binding in natural VT-producing Escherichia coli disease and its relevance for the pathophysiology of hemolytic uremic syndrome remain to be established.

Bacterial Toxins↗
PubMed1994

Survey of family physicians: what is their role in cancer patient care?

In 1993, a survey of randomly-selected family physicians in two regions of Ontario was conducted to assess their views on various aspects of supportive care of patients with cancer. A response rate of 71% was obtained. Results showed that physicians are using preventive and screening techniques in their practices. They are comfortable with most of their roles in supportive cancer care with the exceptions of conveying news of therapy failure and total coordination of care. There is significant dissatisfaction with certain aspects of the timing and content of the consultation letters received from the regional cancer centers. Finally, family physicians expressed the importance of their roles in palliative care.

Adult↗
PubMed1994

Leadership: a nursing perspective.

The Task Force for Collaborative Nursing Education Models was a successful collaboration involving female nurse administrators. The nature of leadership in the Task Force was studied as part of a larger research project examining the process of collaboration that evolved over the 40 months of its existence (October 1987-February 1991). A retrospective qualitative case study approach was used. Data were collected from an analysis of documents that had been generated by the group, and from 36 semi-structured interviews with the 28 Task Force members. Findings and conclusions about leadership were validated during a final group interview with eight selected members. Findings of this study support the following contentions: women lead differently than men, and leadership is a collective process rather than a specialized role assumed by a single person who influences the work of other group members. Leadership was also found to rotate among group members according to the issue being considered and the expertise of those present. These findings did not support the positivist theories of leadership prevalent in current nursing management text books.

Female↗
PubMed1994

A reactionist professional association: the Provisional Council of University Schools and Departments of Nursing, 1942-1948.

From its inception in 1942, the Canadian Association of University Schools of Nursing (CAUSN) has developed into the accrediting agency for university nursing programs and the national voice for its 30 member schools. The current research examines the creation in 1942 of the Provisional Council of University Schools and Departments of Nursing, the forerunner of the CAUSN. The research is historical in design. Primary and secondary data were collected and analyzed inductively. Primary data consisted of archival documents located in the Queen's University Archives, Kingston, Ontario and the Canadian Nurses Association (CNA) Archives, Ottawa, Ontario. Secondary data augmented and corroborated analysis of primary data and included published histories of the CAUSN and the CNA, as well as books and articles about the development of university nursing education in Canada. The impetus for the inception in 1942 of the Provisional Council of University Schools and Departments of Nursing originated with the CNA. The Provisional Council subsequently achieved none of its stated goals. Instead, it focused on its relationship with the CNA and contested the need for its own existance. The Provisional Council was a reactionist association that reflected the uncoordinated nature of university nursing education and the inability of university nursing educators to set aside parochial differences.

Accreditation↗
PubMed1993

Conditional independence models for epidemiological studies with covariate measurement error.

We construct a unifying representation of the structure of measurement error problems with particular reference to situations commonly encountered in epidemiological studies, and outline how estimation of the parameters of interest can be carried out in a Bayesian framework using Gibbs sampling. We show how this approach can be implemented for designs involving continuous measurement errors assessed through a validation substudy, and discuss our results on simulated data.

Analysis of Variance↗
PubMed1993

A Bayesian approach to measurement error problems in epidemiology using conditional independence models.

Risk factors used in epidemiology are often measured with error which can seriously affect the assessment of the relation between risk factors and disease outcome. In this paper, a Bayesian perspective on measurement error problems in epidemiology is taken and it is shown how the information available in this setting can be structured in terms of conditional independence models. The modeling of common designs used in the presence of measurement error (validation group, repeated measures, ancillary data) is described. The authors indicate how Bayesian estimation can be carried out in these settings using Gibbs sampling, a sampling technique which is being increasingly referred to in statistical and biomedical applications. The method is illustrated by analyzing a design with two measuring instruments and no validation group.

Bayes Theorem↗
PubMed1993

Clinical improvement and amyloid regression after liver transplantation in hereditary transthyretin amyloidosis.

Familial amyloid polyneuropathy (FAP) is a fatal autosomal dominant disorder. Progressive peripheral and autonomic neuropathy are associated with neural and visceral deposition of amyloid, derived most commonly from the Met-30 variant of the plasma protein transthyretin. We have reported previously that orthotopic liver transplantation causes prompt replacement of variant transthyretin by the donor wild-type in the plasma. We now report clinical outcome 1-2 years after transplantation. Three of the first four patients have improved general wellbeing, walking ability, and bowel function, and one of them has regained normal bladder and bowel function. There has been little objective improvement in peripheral neuropathy. The fourth patient, who had the most severe neurological deficits and a complicated postoperative course, has not improved but there has been no further deterioration in contrast to the inexorable progression before transplantation. Quantitative scintigraphy with radiolabelled serum amyloid P component showed visceral amyloid deposits in all three patients studied; in two who were followed serially the deposits regressed after transplantation in association with the clinical improvement. Another FAP patient who was also monitored prospectively for 2 years but who did not undergo transplantation, showed, as expected, progression of neuropathy and increased visceral amyloid deposition. Liver transplantation does therefore have important benefits in FAP during the first 2 years after surgery. Neurological decline is halted and amyloid deposits can be mobilised. The best timing and long-term results of the procedure must now be established.

Adult↗
PubMed1993

Serum amyloid P component scintigraphy and turnover studies for diagnosis and quantitative monitoring of AA amyloidosis in juvenile rheumatoid arthritis.

OBJECTIVE: To evaluate aspects of the natural history of AA amyloidosis complicating juvenile rheumatoid arthritis (JRA), and its response to therapy with chlorambucil. METHODS: Scintigraphy and 7-day turnover studies were performed in JRA patients with histologically proven (n = 35) or clinically suspected (n = 30) AA amyloidosis, following intravenous injection of 123I and 125I-labeled serum amyloid P component (SAP). Prospective monitoring studies were performed over 2-3 years in 20 patients with amyloidosis. All but 2 amyloidosis patients were treated with chlorambucil. RESULTS: Positive scanning results were obtained in all patients in whom imaging was performed within 12 years of positive biopsy findings of amyloid and in 5 patients with clinically suspected amyloidosis. Negative scanning results with normal SAP metabolism, indicating regression of amyloid, were obtained in 4 patients whose amyloidosis had been in full clinical remission for more than 12 years. Prospective monitoring studies in patients whose JRA-associated inflammatory activity was in remission demonstrated regression of amyloid in 8 patients and no substantial changes in 8 others; however, in 4 further patients with active inflammation, there was accumulation of amyloid. There was a very poor correlation between the amount of amyloid present at a particular site and the resultant organ dysfunction. CONCLUSION: Radiolabeled SAP scintigraphy and turnover studies are useful complementary tools in the diagnosis, screening, and quantitative monitoring of type AA amyloidosis in JRA. The amyloid deposits may progress and/or regress at different rates in different anatomic sites over short periods.

Adolescent↗
PubMed1993

Childhood leukemia incidence in the vicinity of La Hague nuclear-waste reprocessing facility (France).

The incidence of leukemia is examined in young people (aged under 25 years) living within a 35 km radius of the French nuclear-waste reprocessing plant operating in La Hague, Normandy. During the period 1978-90, a total of 23 cases was diagnosed, giving an incidence rate of 2.99 per 100,000 which is close to the expected rate. In the 'canton' in which the nuclear plant is located, three cases of leukemia were observed compared with 1.2 expected, giving a standardized incidence ratio of 2.5. This nonsignificant finding is compatible with no increased risk and also with a sevenfold excess risk. Therefore, it reinforces the necessity of conducting a case-control survey, which is now planned, to assess the part played by occupational radiation exposure in leukemia incidence for this French area.

Acute Disease↗
PubMed1993

HDL-cholesterol and breast cancer: a joint study in northern Italy and southern France.

The goal of the present study is to evaluate HDL-cholesterol (HDL-C) as a marker of breast cancer (BC) risk. It is based on several epidemiological and biological studies and is justified by the rising incidence of breast cancer throughout the world. A hospital-based study on host-related risk factors and breast cancer, conducted with similar methods in northern Italy and southern France, provided the biological data, the information on the established BC risk factors and on nutrition for 307 cases and 329 controls. This data set allowed for a thorough analysis of the relationship of HDL-C with established risk factors for BC and also of its association with BC at the time of diagnosis. Most of our findings on HDL-C determinants in the control sample are comparable to previous studies. The BC risk factors associated with reproductive life correlate with HDL-C levels: the protective factors are associated with a lower level of HDL-C and inversely. The same is true for nutritional factors such as alcohol. For these determinants, the trend is similar for cases and controls, and HDL-C level appears to be related to oestrogen metabolism. Thus it may be considered as a marker of BC risk. Our results indicate that high HDL-C levels should be especially checked in women aged > or = 60 years, or in premenopausal women presenting a low BMI, or in postmenopausal women with an early menopause.

Breast Neoplasms↗
PubMed1993

Salmonella enteritidis infections in France and the United States: characterization by a deterministic model.

OBJECTIVES: Epidemiological surveillance can be used to identify problems, suggest hypotheses, and assess the effectiveness of preventive actions. These objectives are pursued in the analysis of the dynamic evolution of Salmonella enteritidis infections. In this analysis, development of the epidemic in France and the United States is compared. METHODS: This analysis is based on the formulation of a simple deterministic compartmental model, in which human contact with contaminated food is expressed in terms of a baseline transmission rate. RESULTS: In France, the baseline transmission rate, stable up until 1986, is multiplied by 2.3 in 1987 and by 4.1 in 1988. There is no evidence of a slowdown of the linear rate of increase. In the Middle Atlantic region of the United States, the linear increase of the epidemic is similar to that observed in France. From 1990 a potential effect of the preventive measures is observed. CONCLUSIONS: The pattern of increase of the baseline transmission rate is similar in France and in the Middle Atlantic region of the United States. However, preventive measures, used in both areas, appeared more effective in the United States.

Disease Susceptibility↗
PubMed1993

Scintigraphic quantification and serial monitoring of human visceral amyloid deposits provide evidence for turnover and regression.

Radiolabelled serum amyloid P component scintigraphy provides information on the diagnosis and distribution of amyloid which was not previously available. A simple reproducible method for quantifying the uptake of 123I-labelled serum amyloid P component into individual livers, spleens and kidneys was devised and evaluated in 22 patients with different types of systemic amyloidosis. Prospective studies in 10 patients were undertaken in order to monitor aspects of the natural history of visceral amyloid deposits. Although measurements of tracer uptake were not as discriminating for diagnostic purposes as the opinions of two highly experienced visual observers, the availability of objective scintigraphic parameters should facilitate interpretation of serum amyloid P component scans in centres unfamiliar with the technique. The follow-up studies demonstrated several intriguing features of amyloidogenesis. There was very rapid progression of deposits in some individuals with differential rates of accretion in different organs. The single patient with AL amyloidosis treated with cytotoxic drugs showed substantial regression of hepatic amyloid deposits whilst his splenic amyloid increased. His spleen was then removed and further regression of the hepatic amyloid was observed. It is concluded that quantitative serum amyloid P component scintigraphy is a useful method for assessing visceral amyloid and that the deposits not only progress at extremely variable rates, but can evidently also be mobilized. These findings encourage active therapeutic approaches in the management of amyloidosis.

Adult↗
PubMed1992

Analogues of the dioxolanes dexoxadrol and etoxadrol as potential phencyclidine-like agents. Synthesis and structure-activity relationships.

A series of dioxolane analogues based on dexoxadrol ((4S,6S)-2,2-diphenyl-4-(2-piperidyl)-1,3-dioxolane) and etoxadrol ((2S,4S,6S)-2-ethyl-2-phenyl-4-(2-piperidyl)-1,3-dioxolane) were prepared and tested for their ability to displace [3H]TCP (1-[1-(2-thienyl)cyclohexyl]piperidine) from PCP (1-(1-phenylcyclohexyl)piperidine) binding sites in rat brain tissue homogenates. Qualitative structure-activity relationships within this series were explored through modifications of the three major structural units of dexoxadrol, the piperidine, 1,3-dioxolane, and aromatic rings of the molecule. N-Alkyl derivatives of dexoxadrol were found to be inactive, as were those analogues where the dioxolane ring was modified. Phenyl-substituted etoxadrol analogues were compared to similarly substituted PCP analogues and distinct differences were found in their structure-activity relationships suggesting that the aromatic rings in these two drug classes interact differently with the PCP binding sites. The replacement of the phenyl ring in etoxadrol by either a 2- or 3-thienyl ring led to compounds with affinity comparable to etoxadrol, and the replacement of the ethyl moiety on etoxadrol's dioxolane ring with propyl (7) or isopropyl (8) led to compounds which were more potent than etoxadrol or PCP. The most potent compound was (2S,4S,6S)-2-ethyl- 2-(1-chlorophenyl)-4-(2-piperidyl)-1,3-dioxolane (11), where a chlorine moiety was placed in the ortho position in the aromatic ring of etoxadrol. Its potency was comparable with TCP in vitro.

Analgesics↗
PubMed1992

Analysis of disease risks using ancillary risk factors, with application to job-exposure matrices.

Epidemiological studies of disease can make use of ancillary risk-factors, acquired from individuals outside the disease study. For example, several disease studies might use the same job-exposure matrix to quantify risks due to occupational exposure to industrial agents. We construct a graphical model to combine a logistic regression disease model with models for the ancillary data and the risk-factor distribution in the population. We estimate the graphical model using Gibbs sampling, and in simulations compare it with methods of direct substitution into logistic regression.

Bayes Theorem↗
PubMed1992

Occupational risk factors for acute leukaemia: a case-control study.

A case-control study has been performed for occupational risk factors of acute leukaemia, based on 185 cases more than 30 years old and 513 matched controls. There was a significant excess of polyvalent farming and electronic engineers among professions of cases, and, in addition of metal workers when considering the professions pursued for more than 5 years. The corresponding exposures were analysed through a detailed questionnaire, and assessed by an industrial hygienist after blinding the case-control status. The odds ratios (OR) were computed after adjustment on matching variables and prior chemo- or radiotherapy treatment, and after stratification for the level and total duration of exposure. There was no excess of professional exposure to ionizing radiation among cases. A significant relationship was observed between acute leukaemia and high or medium exposure to benzene, as well as over 10 years high or medium exposure to exhaust gas. In addition a significant relationship was observed with exposure to pesticides--insecticides and/or weed killers--and to electric and magnetic fields (EMF). The relationship with pesticides was significant when considering high or medium exposure to weed killers and more than 10 years exposure to both subtypes of pesticides. The relationship with pesticides and EMF remained significant when confounding factors were taken into consideration and after adjustment on co-exposure to benzene. The cytological studies showed that acute leukaemias following exposure to benzene (high or medium) and to EMF were only of myelogenous subtypes, whereas those following exposure to pesticides were divided between lymphoblastic and myeloblastic subtypes. Cytogenetic studies failed to show increased frequency of chromosomal abnormalities, as described in acute leukaemias secondary to anti-cancer treatments. Our study adds credence to the hypothesis that pesticides and EMF are leukaemogenic agents, together with benzene.

Acute Disease↗