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L Duggan

Publications and source records attributed to L Duggan.

30 records · Page 2Linked to original sources
PubMed1999

Selective in vivo dosimetry in radiotherapy using P-type semiconductor diodes: a reliable quality assurance procedure.

Since 1994, our center has conducted entrance dose measurements on selected patients receiving 6MV x-ray therapy by utilizing a commercial set of p-type semiconductor diodes. We report on three years results representing 386 patients having 1005 measurements and the usefulness of such a system in a radiotherapy department. The 386 patients represent approximately 20% of our total radical treatments. Minimal disruption to patient treatment was achieved. Measurements showed an average variation from expected dose of 0.5% +/- 2.2%. Specific treatment site groups were investigated. Our results show that in vivo dosimetry on a selected group of patients is an effective method of providing an independent verification of dose delivery accuracy.

Humans↗
PubMed1999

Effectiveness of antipsychotic medication in people with intellectual disability and schizophrenia: a systematic review.

The aim of the present study was to determine the efficacy of any antipsychotic medication for treating people with a dual diagnosis of intellectual disability and schizophrenia. The authors performed an electronic search of Biological Abstracts, the Cochrane Schizophrenia Group's Register of trials, the Cochrane Library, EMBASE, PsycLIT and MEDLINE. Unpublished data were sought from pharmaceutical companies. Both authors independently selected the relevant studies from the reports identified in this way. Only one relevant randomized trial was found by the searches (Foote 1958). This study included four people with a dual diagnosis of schizophrenia and intellectual disability, but results were only available for two subjects. The groups to which the other two people were allocated were unclear. Using the methods described, the reviewers found no trial evidence to guide the use of antipsychotic medication for those with both intellectual disability and schizophrenia. Until the urgent need for randomized controlled trials is met, clinical practice will continue to be guided by evidence from trials involving people with schizophrenia but without intellectual disability.

Antipsychotic Agents↗
PubMed1999

Antipsychotic medication for challenging behaviour in people with intellectual disability: a systematic review of randomized controlled trials.

A study was performed to determine the effectiveness of antipsychotic medication for people with intellectual disability (ID) and challenging behaviour. Randomized controlled trials comparing antipsychotic medication to placebo in people with ID and challenging behaviour were identified by electronic searching and hand-searching. Reviewers independently evaluated and analysed data on an intention-to-treat basis. Only three randomized controlled trials could be included in the analyses. These trials provided no evidence as to whether antipsychotic medication does or does not help adults with ID and challenging behaviour. There is limited data on this important issue and good quality research is urgently needed.

Antipsychotic Agents↗
PubMed1998

Dose response of various radiation detectors to synchrotron radiation.

Accurate dosimetry is particularly difficult for low- to medium-energy x-rays as various interaction processes with different dependences on material properties determine the dose distribution in tissue and radiation detectors. Monoenergetic x-rays from synchrotron radiation offer the unique opportunity to study the dose response variation with photon energy of radiation detectors without the compounding effect of the spectral distribution of x-rays from conventional sources. The variation of dose response with photon energies between 10 and 99.6 keV was studied for two TLD materials (LiF:Mg,Ti and LiF:Mg,Cu,P), MOSFET semiconductors, radiographic and radiochromic film. The dose response at synchrotron radiation energies was compared with the one for several superficial/orthovoltage radiation qualities (HVL 1.4 mm Al to 4 mm Cu) and megavoltage photons from a medical linear accelerator. A calibrated parallel plate ionization chamber was taken as the reference dosimeter. The variation of response with x-ray energy was modelled using a two-component model that allows determination of the energy for maximum response as well as its magnitude. MOSFET detectors and the radiographic film were found to overrespond to low-energy x-rays by up to a factor of 7 and 12 respectively, while the radiochromic film underestimated the dose by approximately a factor of 2 at 24 keV. The TLDs showed a slight overresponse with LiF:Mg, Cu, P demonstrating better tissue equivalence than LiF:Mg, Ti (maximum deviation from water less than 25%). The results of the present study demonstrate the usefulness of monoenergetic photons for the study of the energy response of radiation detectors. The variations in energy response observed for the MOSFET detectors and GAF chromic film emphasize the need for a correction for individual dosimeters if accurate dosimetry of low- to medium-energy x-rays is attempted.

Biophysical Phenomena↗
PubMed1997

Yeast Gcn5 functions in two multisubunit complexes to acetylate nucleosomal histones: characterization of an Ada complex and the SAGA (Spt/Ada) complex.

The transcriptional adaptor protein Gcn5 has been identified as a nuclear histone acetyltransferase (HAT). Although recombinant yeast Gcn5 efficiently acetylates free histones, it fails to acetylate histones contained in nucleosomes, indicating that additional components are required for acetylation of chromosomal histones. We report here that Gcn5 functions as a catalytic subunit in two high-molecular-mass native HAT complexes, with apparent molecular masses of 0.8 and 1.8 megadalton (MD), respectively, which acetylate nucleosomal histones. Both the 0.8- and 1.8-MD Gcn5-containing complexes cofractionate with Ada2 and are lost in gcn5delta, ada2delta, or ada3delta yeast strains, illustrating that these HAT complexes are bona fide native Ada-transcriptional adaptor complexes. Importantly, the 1.8-MD adaptor/HAT complex also contains Spt gene products that are linked to TATA-binding protein (TBP) function. This complex is lost in spt20/ada5delta and spt7delta strains and Spt3, Spt7, Spt20/Ada5, Ada2, and Gcn5 all copurify with this nucleosomal HAT complex. Therefore, the 1.8-MD adaptor/HAT complex illustrates an interaction between Ada and Spt gene products and confirms the existence of a complex containing the TBP group of Spt proteins as demonstrated by genetic and biochemical studies. We have named this novel transcription regulatory complex SAGA (Spt-Ada-Gcn5-Acetyltransferase). The function of Gcn5 as a histone acetyltransferase within the Ada and SAGA adaptor complexes indicates the importance of histone acetylation during steps in transcription activation mediated by interactions with transcription activators and general transcription factors (i.e., TBP).

Acetylation↗
PubMed1997

An independent check of treatment plan, prescription and dose calculation as a QA procedure.

In many radiotherapy centres where planning for external beam treatments is performed by radiation therapists, the treatment sheet and its calculations are independently checked by staff from a different educational background, typically a radiotherapy physicist. The benefits of this practice were evaluated in a radiotherapy department with two linear accelerators, one combined superficial-orthovoltage unit and one telecaesium unit. Within the 19 months of the investigation period, 2328 checks were performed on the treatment sheets of 1579 patients. In six cases, errors in excess of 5% were detected, which if uncorrected, could potentially have affected local tumour control or caused normal tissue complications. It was found that an independent check of treatment sheets assists in keeping these errors as low as can be achievable in clinical practice, and suggests that treatment sheet checking and in vivo dosimetry play a complementary role in this aim. Independent treatment sheet checking is an important quality assurance (QA) activity, with additional advantages such as improved communication in the department, education of staff and in vivo dosimetry targeting. Therefore the advantages of the procedure seem to outweigh the additional workload of approximately 0.3 full-time staff per 1000 patients per year.

Adult↗
PubMed1996

Behavioural changes in people with learning disability and dementia: a descriptive study.

The behaviour of 12 people with mild and more severe learning disability and dementia is described using Past Behavioural History Inventory (PBHI), an instrument devised for the description of behaviour in people of normal intelligence and dementia. The PBHI appears sensitive to behavioural changes. The behavioural changes are described and are similar to those seen in people without a learning disability. Carers were unaware of the behavioural changes associated with dementia. The behavioural changes could be used to assist in the earlier diagnosis and management of dementia in people with learning disability.

Activities of Daily Living↗
PubMed1996

Radiotherapy treatment checking procedures throughout Australasia: results of a survey.

In July 1995, a questionnaire was forwarded to thirty two physicists overseeing Radiation Oncology Departments and brachytherapy in hospitals throughout Australia and New Zealand. From the thirty seven hospitals reached by this survey, details were gathered on thirty hospitals, including the Newcastle Mater Hospital. In most radiotherapy centres where treatment planning is performed by radiation therapists, at least some of the treatment sheets and their calculations are double checked by radiotherapy physicists. While 23% checked the treatment sheets of all patients, in the majority of centres physicists were found to check only a minor selection, that is, less than 20% of all treatment sheets. Only in six centres physicists were not involved.

Australia↗
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Holistic Nursing↗