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Biomedical subjects

S Arnott

Publications and source records attributed to S Arnott.

At least 19 recordsLinked to original sources
PubMed2006

Mycobacterium avium subsp. paratuberculosis in lake catchments, in river water abstracted for domestic use, and in effluent from domestic sewage treatment works: diverse opportunities for environmental cycling and human exposure.

Mycobacterium avium subsp. paratuberculosis from infected animals enters surface waters and rivers in runoff from contaminated pastures. We studied the River Tywi in South Wales, United Kingdom, whose catchment comprises 1,100 km2 containing more than a million dairy and beef cattle and more than 1.3 million sheep. The River Tywi is abstracted for the domestic water supply. Between August 2002 and April 2003, 48 of 70 (68.8%) twice-weekly river water samples tested positive by IS900 PCR. In river water, the organisms were associated with a suspended solid which was depleted by the water treatment process. Disposal of contaminated slurry back onto the land established a cycle of environmental persistence. A concentrate from 100 liters of finished water tested negative, but 1 of 54 domestic cold water tanks tested positive, indicating the potential for these pathogens to access domestic outlets. In the separate English Lake District region, with hills up to 980 m, tests for M. avium subsp. paratuberculosis in the high hill lakes and sediments were usually negative, but streams and sediments became positive lower down the catchment. Sediments from 9 of 10 major lakes receiving inflow from these catchments were positive, with sediment cores indicating deposition over at least 40 to 50 years. Two of 12 monthly 1-liter samples of effluent and a single 100-liter sample from the Ambleside sewage treatment works were positive for M. avium subsp. paratuberculosis. Since Lake Ambleside discharges into Lake Windermere, which is available for domestic supply, there is a potential for these organisms to cycle within human populations.

Animals↗
PubMed2005

Mycobacterium avium subsp. paratuberculosis in the catchment area and water of the River Taff in South Wales, United Kingdom, and its potential relationship to clustering of Crohn's disease cases in the city of Cardiff.

In South Wales, United Kingdom, a populated coastal region lies beneath hill pastures grazed by livestock in which Mycobacterium avium subsp. paratuberculosis is endemic. The Taff is a spate river running off the hills and through the principal city of Cardiff. We sampled Taff water above Cardiff twice weekly from November 2001 to November 2002. M. avium subsp. paratuberculosis was detected by IS900 PCR and culture. Thirty-one of 96 daily samples (32.3%) were IS900 PCR positive, and 12 grew M. avium subsp. paratuberculosis bovine strains. Amplicon sequences from colonies were identical to the sequence with GenBank accession no. X16293, whereas 16 of 19 sequences from river water DNA extracts had a single-nucleotide polymorphism at position 214. This is consistent with a different strain of M. avium subsp. paratuberculosis in the river, which is unculturable by the methods we used. Parallel studies showed that M. avium subsp. paratuberculosis remained culturable in lake water microcosms for 632 days and persisted to 841 days. Of four reservoirs controlling the catchment area of the Taff, M. avium subsp. paratuberculosis was present in surface sediments from three and in sediment cores from two, consistent with deposition over at least 50 years. Previous epidemiological research in Cardiff demonstrated a highly significant increase of Crohn's disease in 11 districts. These bordered the river except for a gap on the windward side. A topographical relief map shows that this gap is directly opposite a valley open to the prevailing southwesterly winds. This would influence the distribution of aerosols carrying M. avium subsp. paratuberculosis from the river.

Animals↗
PubMed2000

High-dose treatment with autologous bone marrow support as consolidation of first remission in younger patients with acute myelogenous leukaemia.

BACKGROUND: Debate and controversy remain as to the optimal post-remission therapy for younger patients with acute myelogenous leukaemia (AML). The aim of this study was to evaluate high-dose treatment (HDT) with autologous bone marrow support (ABMS) as consolidation of first complete remission (CR). PATIENTS AND METHODS: One hundred forty-four patients (AML-M3 excluded, median age 38 years, range 15-49 years) received remission induction therapy comprising: adriamycin 25 mg/m2, days 1-3, cytosine arabinoside (ara-C) and 6-thioguanine, both at 100 mg/m2 bid, days 1-7. Patients in whom CR was achieved received two further cycles of the same treatment prior to bone marrow being harvested and cryopreserved. HDT comprised ara-C: 1 g/m2 b.i.d. x six days and total body irradiation (TBI): 200 cGy b.i.d. for three days. Thawed autologous marrow was then re-infused. RESULTS: Complete remission was achieved in 106 of 144 patients (73%) who were thus eligible to receive ara-C + TBI + ABMS; 61 actually received it. Following HDT, the median time to neutrophil recovery (> 0.5 x 10(9)/l) was 25 days (range 11-72 days) and to platelet recovery (> 20 x 10(9)/l), 42 days (range 15-159 days). There were eight treatment-related deaths. Analysis by 'intention to treat' shows both remission duration (log-rank, P = 0.001) and survival (log-rank, P = 0.004) to be significantly longer for the 106 patients eligible to receive HDT than for a historical control group (n = 133) who received identical remission induction and consolidation therapy but without ara-C + TBI + ABMS. With a median follow-up of 5.5 years, 39 of 106 patients remain in CR (37%) and 54 (51% of those in whom CR was achieved) remain alive, with a predicted actuarial survival of 52% at 5 years. CONCLUSIONS: The addition of ara-C + TBI + ABMS to conventional consolidation therapy significantly improved remission duration and survival over those of a historical control group of patients with AML (aged < 50, AML-M3 excluded). HDT was, however, associated with significant treatment-related mortality and slow blood count recovery. The use of ara-C + TBI supported by peripheral blood progenitor cells should make the treatment safer and more widely applicable in AML.

Adolescent↗
PubMed2000

Structure of poly (dT).poly (dA).poly (dT).

The molecular structure of poly (dT).poly (dA).poly (dT) has been determined and refined using the continuous x-ray intensity data on layer lines in the diffraction pattern obtained from an oriented fiber of the DNA. The final R-value for the preferred structure is 0.29 significantly lower than that for plausible alternatives. The molecule forms a 12-fold right-handed triple-helix of pitch 38.4 A and each base triplet is stabilized by a set of four Crick-Watson-Hoogsteen hydrogen bonds. The deoxyribose rings in all the three strands have C2'-endo conformations. The grooveless cylindrical shape of the triple-helix is consistent with the lack of lateral organization in the fiber.

DNA↗
PubMed2000

Structure of Poly (U).poly (A).poly (U).

The molecular structure of poly (U).poly (A).poly (U) has been determined and refined using the continuous x-ray intensity data on layer lines in the diffraction pattern obtained from an oriented fiber of the RNA. The final R-value for the preferred structure is 0.24, far lower than that for the plausible alternatives. The polymer forms an 11-fold right-handed triple-helix of pitch 33.5A and each base triplet is stabilized by Crick-Watson-Hoogsteen hydrogen bonds. The ribose rings in the three strands have C3'-endo, C2'-endo and C2'-endo conformations, respectively. The helix derives additional stability through systematic interchain hydrogen bonds involving ribose hydroxyls and uracil bases. The relatively grooveless cylindrical shape of the triple-helix is consistent with the lack of lateral organization.

DNA↗
PubMed2000

Structure of poly (I).poly (A).poly (I).

The molecular structure of poly (I).poly (A).poly (I) has been determined and refined using the continuous intensity data on layer lines in the x-ray diffraction pattern obtained from an oriented fiber of this polymorphic RNA complex. The polymer forms a 12-fold right-handed triple-helix of pitch 39.7A and each base-triplet is stabilized by quasi Crick-Watson-Hoogsteen hydrogen bonds. The ribose rings in all the three strands have C3'-endo conformations. The final R-value for this best structure is 0.24 and the x-ray fit is significantly superior to all the alternative structures where the different chains might have different furanose conformations. This all-purine triple-helix, counter-intuitively, has a diameter roughly 3A shorter than that of DNA and RNA triple-helices containing a homopurine and two complementary homopyrimidine strands. Its compact, grooveless cylindrical shape is consistent with the lack of lateral organization.

Adenine↗
PubMed1998

Medicolegal issues in clinical practice.

This article reviews a number of medicolegal issues, such as the capacity of the patient, the principles of consent and issues of patient confidentiality, which doctors will face in their everyday work. For each issue the basic principles are outlined and further sources are given for more detailed information.

Confidentiality↗
PubMed1996

Emotional support for cancer patients: what do patients really want?

For many cancer patients and their families the experience of cancer is an intensely stressful one. Emotional support is important for most cancer patients during their illness and can be gained from different people and services. This study evaluates patients' attitudes to different sources of support and rates their satisfaction with sources already used. A total of 431 patients completed a questionnaire covering the use of different sources, including individuals, support groups and information sources. The questionnaire also incorporated validated measurements of anxiety, depression and locus of control. The results revealed that the three most important sources of emotional support were senior registrars (73%) and family (73%), followed by consultants (63%). Patients would prefer doctor- and nurse-led support groups to patient only-led groups (26% vs 12%). Pamphlets, such as the BACUP booklets, proved the most important of the informational sources sought (50%). A total of 86% of patients were satisfied or very satisfied with the emotional support received. Patients who expressed dissatisfaction with their emotional support were significantly more likely to be anxious and depressed (P < 0.001). Patients who used information sources were more likely to have a higher locus of control over the course of their disease. These results show how important the doctor's role is in the provision of emotional support.

Adolescent↗
PubMed1996

The structure of B-DNA in oriented fibers.

Native, general sequence B-form DNA in uniaxially oriented fibers is a ten-fold helix with identical antiparallel strands: this is to say the molecular symmetry is 2 2 10(1). The diffraction patterns indicate that local variations, however significant, must be modest. This is true also for the lithium salt of calf thymus DNA in fibers that are polycrystalline as well as oriented. The contents of its orthorhombic unit cells are arranged with P2(1)2(1)2(1) symmetry which permits the molecular symmetry to be merely two-fold. The molecular structure of DNA in such conditions resembles, conformationally and molecularly, that of B-type DNA in oligonucleotide single crystals and in oriented polycrystalline fibers of polyoligonucleotides, and therefore provides a basis for evaluating the variations that may be due to sequence effects in polyoligonucleotides in fibers and oligonucleotides in single crystals.

Base Composition↗
PubMed1995

Results of a randomized trial comparing MVPP chemotherapy with a hybrid regimen, ChlVPP/EVA, in the initial treatment of Hodgkin's disease.

PURPOSE AND METHODS: Between December 1984 and August 1992, 423 patients with newly diagnosed Hodgkin's disease (HD) were entered onto a randomized clinical trial that compared the regimen of mechlorethamine, vinblastine, procarbazine, and prednisone (MVPP) with a doxorubicin-containing hybrid regimen (chlorambucil, vinblastine, procarbazine, and prednisone/etoposide, vincristine, and doxorubicin [ChlVPP/EVA]). Median age for the group was 29.5 years (range, 15.2 to 68.8), and 52% had bulk disease. RESULTS: After chemotherapy, patients in the hybrid arm of the trial had a higher complete remission (CR) rate (68.1% v 55.3%) and a lower failure rate (2.4% v 12.5%) than those in the MVPP arm. There were also fewer deaths during treatment in the hybrid arm of the trial (five v 13). With a median follow-up period for survivors of 4.5 years (range, 0 to 9), actuarial 5-year progression-free survival (PFS) for all cases is 80% in the hybrid arm and 66% in the MVPP arm (P = .005). A nonsignificant trend toward a better overall survival in the hybrid arm of the trial has also been identified. CONCLUSION: These results suggest that ChlVPP/EVA hybrid is superior to MVPP in the treatment of HD. It has therefore been adopted as standard first-line therapy at the two centers.

Adolescent↗
PubMed1992

Management of stage II Hodgkin's disease: 15 years experience at St. Bartholomew's Hospital.

One hundred seventy-seven consecutive patients with newly diagnosed stage II Hodgkin's disease (HD) (supradragmatic 157; infra diaphragmatic 20) were treated at St. Bartholomew's Hospital on the basis of pathologic stage (PS) in 84 (IIA 69; IIB 15) and clinical stage (CS) in 93 (IIA 33, IIB 60) between January 1968 and December 1984. The median follow up is 13 years. Overall, complete remission (CR) was achieved in 143 patients (75%) of whom 53 have had a recurrence. One hundred twenty-seven patients remain alive, the cumulative predicted survival at 15 yrs being 70%. Mantle radiotherapy was prescribed to 88 patients with supradiaphragmatic HD, of whom 75 entered CR and 9 achieved good partial remission (GPR) (95%). The duration of remission correlated strongly with ESR (greater than 50 mm/h) and mediastinal thoracic ratio (less than 33% vs. greater than 33%) in a multivariate analysis (p = 0.05 and 0.02, respectively). 46/88 patients remain in continuous first remission, the median duration of remission having not reached at 15 years. Combined modality therapy or chemotherapy alone was prescribed to 69 patients with supradiaphragmatic HD, CR being achieved in 51 patients and GPR in 8 at the completion of all therapy. 48/59 patients continue in first remission. The duration of remission of patients receiving combined modality therapy or CT alone was significantly longer (p = 0.002) than that of patients receiving RT alone, in spite of the fact that the former group comprised predominantly of patients with unfavourable features.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1991

Ordered water in hydrated solid-state polysaccharide systems.

Water molecules within a monolayer or so of macromolecular surfaces are often located in well-defined positions and have restricted mobility. These ordered water molecules play a role in stabilizing polysaccharide ordered structures and intermolecular interactions that are the basis of the rheological properties utilized in food systems. X-ray fiber diffraction can be used to determine the three-dimensional structures of polysaccharides in solid, but well-hydrated, polycrystalline fibers. In favorable cases, difference Fourier synthesis can be used to locate ordered water molecules in these systems, allowing one to visualize their functionally important interactions. These studies provide relevant evidence regarding water interactions in more hydrated systems and in solution. The functionality of ordered water in some polysaccharides used in food systems, as well as in some connective tissue glycosaminoglycans where the ordered water has been defined in considerable detail, as determined by fiber diffraction, is described in this chapter. These structures allow one to derive some general features of the role of ordered water in such systems.

Carbohydrate Sequence↗
PubMed1991

Myeloablative therapy with autologous bone marrow transplantation as consolidation of remission in patients with follicular lymphoma.

A study has been in progress since June 1985 to evaluate the use of myeloablative therapy (cyclophosphamide [60 mg/kg x 2] and total body irradiation [200 cGy x 6]) followed by reinfusion of autologous bone marrow in patients in second or subsequent remission of B-cell non-Hodgkin's lymphoma. The marrow mononuclear cell fraction is being treated in vitro with three cycles of the monoclonal antibody anti-CD20 (anti-B1, Coulter Immunology) and baby rabbit complement (Pel-Freez). Thirty-eight patients with follicular lymphoma (age range 29-61 years, median 43) have been treated to date. At the time of treatment, 28 patients were in second remission, 7 were in third, and 3 were in more than third remission. Twenty-three patients were in complete remission, 15 had residual disease (7 had lymph nodes less than 2 cm diameter, 4 had less than 10% bone marrow infiltration, 1 had involvement of lymph nodes and bone marrow, and 3 had involvement at other sites). Of the 38 study patients, 32 are alive; 6 have died, 4 in remission. Two of the deaths were treatment related: 1 resulted from cerebral haemorrhage at 29 days; 1 resulted from systemic fungal infection at three months). One patient died from secondary acute myelogenous leukaemia at four years, and another from an unrelated cause. Two patients died following relapse. The median time to engraftment was 28 days (range 15-45 days) for neutrophils greater than 0.5 x 10(9)/L and 28 days (range 15-46 days) for platelets greater than 20 x 10(9)/L.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

Radiotherapy for stage I Hodgkin's disease: 20 years experience at St Bartholomew's Hospital.

One hundred and one consecutive patients with newly diagnosed stage I Hodgkin's disease (HD) received treatment at St Bartholomew's Hospital, between 1968 and 1987, with a median follow-up of 12 years. Eleven patients have been excluded from detailed analysis because they either received involved field radiotherapy (RT) or radiotherapy with chemotherapy or were lost to follow-up. Actuarial analysis predicts 78% to be alive and without relapse of Hodgkin's disease at 15 years. Ninety evaluable patients (clinical stage (CS) 24; pathological stage (PS) 66) received either mantle or inverted 'Y' RT and form the basis of this analysis. The median age was 33 years (63 men, 27 women). Histology at presentation was nodular sclerosing (39), lymphocytic predominant (27) or mixed cellularity (24). The presenting site was neck (78), axilla (6) groin (4) and mediastinum (2). Complete remission was achieved in all evaluable patients, the actuarial proportion in remission being 75% at 15 years. Factors predictive of a prolonged remission were pathological staging versus clinical staging (P = 0.02) and lymph node size less than 3 cm (P = 0.04). Actuarial overall survival in these 90 patients was 75% at 15 years and none of the above factors correlated with survival. Relapse of HD has occurred in 18 patients (5 within RT field, 10 without and 3 in both). Second remission was achieved in 15/18. The actuarial rate of second remission and survival was 40% at 10 years. Sixteen patients have died, 7 of Hodgkin's disease, 7 of unrelated causes and 2 of second malignancy. A further 3 patients who developed second malignancy are still alive. At 15 years the actuarial mortality related to HD was 12%. These results confirm the importance of long follow up to assess the efficacy of primary therapy.

Adolescent↗
PubMed1989

A re-examination of the crystal structure of A-DNA using fiber diffraction data.

Classical A-DNA helices with h = 0.25 nm may represent the greatest mass per unit length attainable by polynucleotide duplexes. The X-ray diffraction pattern from polycrystalline and well-oriented fibers of calf thymus DNA in its A-form has been carefully re-examined. Indexing on the basis of a C-face-centered monoclinic unit cell of dimensions a = 2.170 nm, b = 3.990 nm, c = 2.803 nm and beta = 96.82 degrees is superior to alternatives that have been proposed. Two right-handed. Watson-Crick base-paired, helical DNA chains with 2 X 11 nucleotides per 2.803 nm pitch, each carrying C3'-endo furanose rings, pass through the unit cell. The crystallography requires the two chains in the duplex to be antiparallel and conformationally identical but the 11 nucleotides in each pitch may be distinct. However, a secondary structure with a mononucleotide asymmetric unit provides as good an X-ray agreement as one with 11 distinct nucleotides. This relative lack of variability is quite different from what is observed in fibrous B-DNAs.

Animals↗